YARN MONITORING DEVICE, YARN WINDING MACHINE AND YARN
MONITORING METHOD
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention mainly relates to a yarn monitoring device adapted to monitor a travelling yarn.
2. Description of the Related Art
A yarn winding machine configured to wind a yarn around a bobbin such as a spinning machine and an automatic winder is conventionally known. This type of yarn winding machine includes a yarn monitoring device (yarn clearer) . An optical yarn monitoring device irradiates the travelling yarn with light and measures transmitted light transmitted through the yarn or reflected light reflected by the yarn to monitor the state of the yarn in real time and detect a yarn defect (portion with abnormality in quality of the yarn).
Japanese Unexamined Patent Publication Nos. 2013-204190 and 2013-203527, and Japanese Patent No. 3707413 disclose an optical yarn monitoring device.
The amount of light (light projecting amount) radiated from a light projecting section of the yarn monitoring device may change by temperature drift. In particular, during a constant period immediately after power of the yarn monitoring device is turned on, the temperature of the light projecting section may be greatly increased and the light projecting amount may be lowered within a few seconds before the introduction of the yarn. As a result, when the yarn is introduced into the yarn
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monitoring device after a lapse of a few seconds since an evaluation reference value (zero point) of the yarn monitoring device has been set, the yarn monitoring device cannot accurately detect the state of the yarn. Furthermore, properties of the yarn monitoring device may change not only due to the heat of the light projecting section but also due to humidity and the like, for example. In the case of a capacitance yarn monitoring device, humidity affects the properties of the yarn monitoring device.
Japanese Unexamined Patent Publication Nos. 2013-204190 and 2013-203527, and Japanese Patent No. 3707413 describe adjusting an evaluation reference value of the yarn monitoring device, but do not describe a technique of adjusting the evaluation reference value taking the temperature drift into consideration.
BRIEF SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and a main obj ect thereof is to provide a yarn monitoring device capable of reducing influence of change in environment and accurately detecting a state of the yarn.
The problems to be solved by the present invention are as described above, and now, the means and effects for solving such problems will be described.
According to a first aspect of the present invention, a yarn monitoring device having the following configuration is provided. Specifically, the yarn monitoring device includes a detecting section, an acquiring section, a setting section, and an evaluating section. The detecting
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section is adapted to output a detection value corresponding to presence/absence of a yarn in a detection region and corresponding to a state of a yarn when the yarn exists in the detection region. The acquiring section is adapted to acquire the detection value in a state where the yarn does not exist in the detection region. The setting section is adapted to set an evaluation reference value to be used in evaluating the state of the yarn. The evaluating section is adapted to evaluate the state of the yarn based on the evaluation reference value set by the setting section and the detection value output by the detecting section. The setting section sets the evaluation reference value based on at least one of a plurality of the detection values acquired by repeating the acquisition of the detection value by the acquiring section until the yarn is introduced to the detection region. Alternatively, the setting section sets the evaluation reference value based on the one or the plurality of detection values acquired by the acquiring section at a predetermined timing. The predetermined timing is determined based on a time acquired by the acquiring section from outside, the time at which the yarn is introduced to the detection region.
According to a second aspect of the present invention, a yarn winding machine having the following configuration is provided. Specifically, the yarn winding machine includes the yarn monitoring device, a winding section, a yarn joining device, and a yarn catching and guiding device. The winding section is adapted to wind the yarn to form a package. The yarn joining device is adapted to carry out a yarn joining operation. The yarn catching and guiding device is adapted to guide the yarn to the yarn joining
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device. The acquiring section acquires one or a plurality of the detection values at a timing determined based on a timing at which the yarn catching and guiding device guides the yarn to the yarn joining device. The setting section sets, as the evaluation reference value, the one detection value or an average value of the plurality of detection values acquired by the acquiring section at the determined timing.
According to a third aspect of the present invention, a yarn monitoring method having the following configuration is provided. Specifically, the yarn monitoring method comprises detecting a value corresponding to presence/absence of a yarn in a detection region and corresponding to a state of the yarn when the yarn exists in the detection region, acquiring the detection value when the yarn does not exist in the detection region, setting an evaluation reference value to be used in evaluating the state of the yarn, and evaluating the state of the yarn based on the evaluation reference value set by the setting section and the detection value output by the detecting section, and is characterized by setting the evaluation reference value based on at least one of a plurality of the detection values acquired by repeating the acquisition of the detection value until the yarn is introduced into the detection region.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view schematically illustrating a
yarn winding unit according to one embodiment of the present
invention;
FIG. 2 is a side view of a yarn winding unit
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illustrating a state where yarn ends are caught by a first yarn catching device and a second yarn catching device;
FIG. 3 is a side view of the yarn winding unit illustrating a state where the yarn ends are guided to a yarn joining device by the first yarn catching device and the second yarn catching device;
FIG. 4 is a block diagram illustrating an electrical configuration of a yarn monitoring device;
FIG. 5 is a graph for describing influence of a temperature drift with respect to the detection value;
FIG. 6 is a graph for describing a process of a case in which the detection value is greatly increased by the influence of the temperature drift;
FIG. 7 is a graph illustrating an example of a transition of the detection value when the yarn is introduced to the detection region;
FIG. 8 is a graph illustrating another example of a transition of the detection value when the yarn is introduced to the detection region;
FIG. 9 is a flowchart illustrating a process carried out by a yarn monitoring control section; and
FIG. 10 is a graph describing a process of a case in which the yarn is left for a long period of time after being introduced to the detection region.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Embodiments of the present invention will be hereinafter described with reference to the drawings. FIG 1 is a schematic side view of a yarn winding unit 1 arranged in a yarn winding machine according to an embodiment of the present invention.
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The yarn winding machine of the present embodiment has a configuration in which a plurality of yarn winding units 1 are arranged in a row. The yarn winding machine includes a machine management device (not illustrated) that intensively manages the yarn winding unit 1.
The yarn winding unit 1 illustrated in FIG. 1 is configured to wind a yarn 10 supplied from a yarn supplying section (not illustrated) around a winding bobbin 21 to form a package 20 . When the yarn winding machine is an automatic winder, as illustrated in FIG. 1, a mechanism adapted to support the yarn supplying bobbin corresponds to the yarn supplying section.
Each yarn winding unit 1 includes a unit control section 30. The unit control section 30 is configured by hardware such as CPU, ROM, and RAM, and software such as a control program stored in the ROM and/or the RAM. With the cooperative operation of the hardware and the software, the unit control section 30 controls each component of the yarn winding unit 1. The unit control section 30 of each yarn winding unit 1 is configured to be able to communicate with the machine management device. Thus, the operation of each yarn winding unit 1 can be intensively managed by the machine management device.
The yarn winding unit 1 includes, in order from upstream in a yarn travelling direction, the yarn supplying section, an upstream guide 11, a first yarn catching device (yarn catching and guiding device) 12, a second yarn catching device (yarn catching and guiding device) 13, a yarn joining device 14, a yarn monitoring device 15, a downstream guide 17, and a winding section 18.
The upstream guide 11 is arranged slightly upstream
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of the yarn supplying section. The upstream guide 11 guides the yarn 10 fed from the yarn supplying section.
The first yarn catching device 12 is configured to be swingable, as illustrated in FIGS. 1 to 3, when the unit control section 30 drives a motor (not illustrated) . The first yarn catching device 12 is connected to a negative pressure source (not illustrated), and can generate a suction flow at a distal end side (opposite side of the center of swing) of the first yarn catching device 12.
The second yarn catching device 13 is configured to be swingable, similarly to the first yarn catching device 12, when the unit control section 30 drives a motor (not illustrated). The second yarn catching device 13 is connected to a negative pressure source (not illustrated) , and can generate a suction flow at a distal end side (opposite side of the center of swing) of the second yarn catching device 13.
When the yarn 10 between the yarn supplying section and the winding section 18 is disconnected for some reason, the first yarn catching device 12 is swung towards the yarn supplying section to suck and catch the yarn end from the yarn supplying section, as illustrated in FIG. 2. The second yarn catching device 13 is swung towards the winding section 18 to suck and catch the yarn end of the package 20.
Thereafter, the first yarn catching device 12 and the second yarn catching device 13 are respectively swung towards the yarn joining device 14 while sucking the yarn ends. Thus, the yarn end from the yarn supplying section and the yarn end from the winding section 18 are guided to the yarn joining device 14, as illustrated in FIG. 3.
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The yarn joining device 14 is configured as a pneumatic splicer that acts a whirling airflow on the yarn end from the yarn supplying section and the yarn end from the winding section 18 to twist and connect the two yarn ends. However, the yarn joining device 14 is not limited thereto, and may be a mechanical knotter, for example.
In a series of steps of the yarn joining operation, the timing at which the first yarn catching device 12 and the second yarn catching device 13 are swung is controlled by the unit control section 30. The unit control section 30 drives the first yarn catching device 12 and the second yarn catching device 13, for example, after a predetermined time from occurrence of yarn breakage.
The yarn monitoring device 15 monitors the state (thickness, mixture of foreign substance such as color yarn, polypropylene, and the like) of the travelling yarn 10, and detects a yarn defect (portion with abnormality in yarn 10) contained in the yarn 10. The yarn monitoring device 15 also includes a cutter (cutting device) 16 adapted to cut the yarn 10 when the yarn monitoring device 15 detects the yarn defect. The detailed configuration of the yarn monitoring device 15 will be described later.
The downstream guide 17 is arranged slightly downstream of the yarn monitoring device 15. The downstream guide 17 guides the yarn 10 fed to the winding section 18.
The winding section 18 includes a package supporting section (not illustrated) and a winding drum 19. The winding drum 19 is driven while making contact with the outer peripheral surface of the winding bobbin 21 or the package 20. The winding section 18 drives the winding drum
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19 with a motor (not illustrated) and winds the yarn 10 while traversing the yarn 10 while rotating the package 20 making contact with the winding drum 19 to form the package 20. The winding drum 19 is provided with a groove for 5 traversing.
The method for carrying out the traversing is arbitrary, and the traverse device may be individually arranged for each yarn winding unit 1 or one traverse device may traverse the yarn 10 of a plurality of yarn winding units
10 1. Furthermore, the configuration of the winding section 18 is not limited to the above-described configuration. For example, a configuration including a groove-less contact roller and an arm-type traverse device independent from the contact roller may be adopted in place of the
15 winding drum 19 with grooves. In such a configuration, the winding bobbin 21 (package 20) is directly driven by the motor. The package 20 is formed by winding the yarn 10 while traversing the yarn 10 by the arm-type traverse device with the winding bobbin 21 (package 20) making contact with the
20 contact roller.
When the yarn 10 of a predetermined length is wound around the winding bobbin 21 and the package 20 becomes fully wound, the yarn 10 is automatically cut by the cutter 16 of the yarn monitoring device 15 or by other cutting means,
25 and the winding of the winding section 18 is stopped. Thereafter, the package 20 is detached from the package supporting section by an automatic doffing device or by a manual operation of an operator, and an empty winding bobbin 21 is attached to the package supporting section instead
30 and the winding is resumed. The automatic doffing device is moved to the yarn winding unit 1 that issued a doffing
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request signal, for example, to collect the package 20.
Thereafter, the automatic doffing device attaches a new
winding bobbin 21 to the package supporting section, and
carries out a predetermined yarn hooking operation.
5 Next, a description will be made on the details of
the yarn monitoring device 15, in particular, the electrical configuration with reference to FIG. 4. FIG. 4 is a block diagram illustrating an electrical configuration of the yarn monitoring device 15.
10 As illustrated in FIG. 4, the yarn monitoring device
15 includes an optical sensor unit (detecting section) 35 and a yarn monitoring control section 50.
The sensor unit 35 can measure the state of the yarn 10. The sensor unit 35 includes a drive circuit 40, a light
15 projecting section 41, a light receiving section 42, an amplifier 43, a high-pass filter 44, an amplifier circuit 45, and a display lamp (display) 46. The cutter 16 is attached to a housing of the sensor unit 35.
The light projecting section 41 includes a light
20 emitting element configured by a light emitting diode (LED). The light projecting section 41 irradiates a space (slit-shaped recess of FIG. 4) through which the yarn 10 travels with light at a light amount corresponding to a drive voltage input from the drive circuit 40. The drive
25 voltage generated by the drive circuit 40 is determined based on an electrical signal input from a DA converter 52 arranged in the yarn monitoring control section 50.
The light receiving section 42 is arranged on an opposite side of the light projecting section 41 with a yarn
30 path therebetween. The light receiving section 42 includes a light receiving element configured by a
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photodiode and the like. The light receiving section 42 receives transmitted light of the light radiated from the light projecting section 41 onto the yarn 10, and outputs the electrical signal (voltage) corresponding to the light 5 receiving amount. The electrical signal changes according to the shape (cross-sectional shape) of the yarn 10 existing in a detection region 36. The transmitted light referred to herein is the light that reached the light receiving section 42 when the light output from the light projecting
10 section 41 is partially shielded by the existence of the yarn 10. In other words, the transmitted light is the light that passed the yarn 10. The detection region 36 is a region, in the slit-like recess, where the light from the light projecting section 41 collides, and is a region where the
15 yarn 10 can be detected according to the light receiving amount of the light receiving section 42.
The electrical signal output by the light receiving section 42 is amplified by the amplifier 43, and thereafter, a signal of a predetermined high frequency is extracted with
20 the high-pass filter 44, and again amplified with the amplifier circuit 45. An inversion process is carried out in the amplifier 43, and the electrical signal output by the amplifier 43 becomes smaller as the light receiving amount of the light receiving section 42 is greater. The
25 electrical signal amplified by the amplifier 43 and the amplifier circuit 45 is output as a detection value from the sensor unit 35, and converted to a digital signal by an AD converter 51 of the yarn monitoring control section 50.
30 The display lamp 46 is fixed to a housing of the sensor
unit 35, for example, and indicates the operation state of
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the yarn monitoring device 15 to the operator by being turned ON and OFF. In the present embodiment, the display lamp 46 is configured as a so-called two color LED, and can be lighted in green and red, for example. The lighting 5 state of the display lamp 46 is controlled by the yarn monitoring control section 50.
The cutter 16 is arranged in proximity to the detection region 36 formed in the housing of the sensor unit 35. The cutter 16 includes a cutting blade (not
10 illustrated) driven by a solenoid, for example. The cutter 16 is electrically connected to the yarn monitoring control section 50, and is configured to cut the yarn 10 based on a cutting signal output by the yarn monitoring control section 50.
15 The yarn monitoring control section 50 stores, in a
storage section 57 to be described later, an evaluation reference value (zero point) obtained from the detection value output by the sensor unit 35 when the yarn 10 does not exist in the detection region 36. An evaluating section
20 53 of the yarn monitoring control section 50 compares the evaluation reference value with the detection value, which is output from time to time by the sensor unit 35 when the yarn 10 exists in the detection region 36, to evaluate (measure) the state of the yarn 10.
25 Next, a description will be made on an adjusting
process, a measuring process, and a correcting process performed by the yarn monitoring device 15. The yarn monitoring control section 50 includes an adjusting section 54, an acquiring section 55, a yarn presence/absence
30 determining section 56, a setting section 58, and the storage section 57, as components for carrying out such
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processes. Specifically, the yarn monitoring control section 50 is configured as a computer including hardware such as CPU, ROM, and RAM, and software such as a control program is stored in the ROM and/or the RAM. With the 5 cooperative operation of the hardware and the software, the yarn monitoring control section 50 can operate as the adjusting section 54, the acquiring section 55, the yarn presence/absence determining section 56, the setting section 58, and the like.
10 The adjusting section 54 performs the adjusting
process. The adjusting process is a process of adjusting a drive voltage to be applied on the light projecting section 41 in the sensor unit 35 such that the detection value (specifically, output voltage) output by the sensor
15 unit 35 coincides with a predetermined adjustment reference value in a state where the yarn 10 does not exist in the detection region 36 of the yarn monitoring device 15.
The acquiring section 55 performs the measuring process. The measuring process is a process of controlling
20 the sensor unit 35 such that the voltage adjusted by the adjusting process is applied to the light projecting section 41 and acquiring the detection value actually output by the sensor unit 35 in a state where the yarn 10 does not exist in the detection region 36 of the yarn
25 monitoring device 15. The detection value (specifically, output voltage of sensor unit 35) obtained in this manner is assumed to be a value substantially the same as the adjustment reference value in the adjusting process, but may be a diverged value due to the influence of change in
30 environment (temperature drift, and the like), for example. Whether or not the detection value acquired by the acquiring
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section 55 satisfies a predetermined condition (specifically, whether or not the detection value is smaller than a normal range threshold value, to be described later) is determined, and the detection value satisfying 5 the condition is stored in the storage section 57, to be described later.
The yarn presence/absence determining section 56 determines whether or not the yarn 10 exists in the detection region 36 (particularly, yarn path) of the yarn
10 monitoring device 15, and whether or not the yarn 10 is introduced to the detection region 36 (particularly, yarn path) based on the detection value acquired by the acquiring section 55. Specifically, the yarn presence/absence determining section 56 determines that the yarn 10 exists
15 in the yarn path (yarn is present) if the output voltage of the sensor unit 35 is greater than or equal to a predetermined threshold value (yarn presence/absence determination threshold value), and determines that the yarn 10 does not exist in the yarn path (yarn is absent)
20 if the output voltage is not greater than or equal to the predetermined threshold value. The detection region 36 is a space having a predetermined size. The yarn path in the detection region 36 can be represented as a position where the yarn 10 travels, the position being regulated by a pair
25 of upper and lower yarn path guides (not illustrated) (position of one point in plan view: predetermined position).
The storage section 57 has a storage region where the content can be updated, and for example, is realized by a
30 rewritable volatile or non-volatile memory (e.g., RAM and EEPROM) and the like. The storage section 57 can store
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various parameters and the like for controlling the yarn monitoring device 15.
Specifically, the storage section 57 can store a plurality of measurement values obtained by the acquiring 5 section 55. In other words, instead of performing the measuring process only once, the acquiring section 55 repeatedly performs, for a plurality of times, a measuring process for every predetermined time interval until the yarn 10 is introduced to the yarn path in the detection
10 region 36 of the yarn monitoring device 15 (position of yarn 10 is defined in yarn path: positioning) to acquire the detection value each time. The storage section 57 can store the data of the detection value for a predetermined number of times in the order of time series.
15 The storage section 57 can store a normal range
threshold value (first threshold value) for defining the boundary of the range (predetermined range), which the detection value is to usually take, when the yarn 10 does not exist in the detection region 36 of the yarn monitoring
20 device 15. If the detection value of the acquiring section 55 is outside the range defined with the normal range threshold value, such a detection value is assumed to be abnormal and is not stored in the storage section 57.
Although the details will be described later, the
25 evaluation reference value is defined based on the detection value stored in the storage section 57. Therefore, if the detection value obtained by the acquiring section 55 is greater than or equal to the normal range threshold value, such irregular detection value is not
30 stored in the storage section 57 and thus is not used for the determination of the evaluation reference value by the
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setting section 58.
Furthermore, the storage section 57 may store the yarn presence/absence determination threshold value (second threshold value) described above, which is the 5 threshold value used as a boundary for the yarn presence/absence determining section 56 to determine the presence/absence of the yarn 10. A value greater than the normal range threshold value (value close to the value of the state where the yarn exists) is set for the yarn
10 presence/absence determination threshold value. In the present embodiment, the inversion process is carried out in the amplifier 43 so that the detection value becomes smaller as the light receiving amount of the light receiving section 42 is greater, but such an inversion process may
15 not be carried out. When the inversion process is not carried out, the magnitude relationship of the detection value is reversed. In other words, a value smaller than the normal range threshold value (value close to the value of the state where the yarn exists) is set for the yarn
20 presence/absence determination threshold value. The yarn presence/absence determination threshold value is a value outside the normal range regardless of the presence/absence of the inversion process.
The storage section 57 can also store a set value of
25 the evaluation reference value determined by the setting section 58, to be described later. The evaluating section 53 evaluates the state of the yarn 10 by comparing with the evaluation reference value. Specifically, an average value of the difference between the voltage set for the
30 evaluation reference value and the voltage obtained from the sensor unit 35 with the yarn 10 in the detection region
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36 of the yarn monitoring device 15 is used for the monitoring of the yarn 10 (e.g., calculation of average thickness of yarn 10).
The setting section 58 determines (calculates) the 5 value of the evaluation reference value based on the detection value satisfying a predetermined condition out of the detection values obtained by the acquiring section 55 and stored in the storage section 57, and stores the result in the storage section 57 as a new set value.
10 Therefore, in the present embodiment, “correction” in the correcting process means re-storing the new evaluation reference value in the storage section 57. In other words, the correcting process is not a process of changing the reference value by substantively adjusting the drive
15 voltage to apply on the light projecting section 41, but
is a process of changing the reference value in computation.
A stationary time counting section 59 counts the time
during which the yarn 10 is stationary without starting to
travel since the yarn presence/absence determining section
20 56 determines that the yarn is present. The count value is used to determine whether or not to carry out forcible cutting of the yarn 10, to be described later.
Next, a description will be made on the determination of the evaluation reference value in the present
25 embodiment.
As described above, the light projecting amount of the light projecting section 41 and the light receiving amount of the light receiving section 42 may vary due to, for example, various causes such as change in the
30 surrounding environment (temperature, humidity, and the like), attachment of contamination, and the like.
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Conventionally, the adjusting process of adjusting the drive voltage of the light projecting section 41 is carried out, and then, the yarn is monitored with the light receiving amount (detection value) measured immediately 5 after the adjusting process as a reference.
However, in the present embodiment, the light projecting section 41 is configured by an LED. Therefore, for example, immediately after the power is turned on in the yarn monitoring device 15, even if the light receiving
10 amount is measured immediately after performing the adjusting process, the amount (light projecting amount) of the light radiated from the light projecting section 41 may change as the temperature of the light projecting section 41 gradually rises (temperature drift) after the
15 measurement of the light receiving amount.
The change in the light projecting amount of the light projecting section 41 influences the evaluation of the state of the yarn 10, and the like. The graph of FIG. 5 illustrates change in the detection value in an ideal case
20 without the temperature drift (broken line) and in a case with the temperature drift (solid line). If the temperature drift does not occur, the obtained detection value is constant until the yarn 10 is introduced to the detection region 36 of the yarn monitoring device 15 after
25 the adjusting process. If the temperature drift occurs, the detection value starts to gradually increase immediately after the adjusting process.
In this regard, the yarn 10 introduced to the detection region 36 has been evaluated in the related art
30 with the detection value immediately after the adjusting process as a reference. Problems do not arise if the
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temperature drift does not occur, but actually, the temperature drift easily occurs particularly immediately after the power-on. Thus, in the conventional method, the average value of the thickness of the yarn 10 may include 5 an error corresponding to the temperature drift.
On the other hand, in the present embodiment, the detection value acquired at the timing immediately before the yarn 10 is introduced to the detection region 36 rather than immediately after the adjusting process is used as the
10 evaluation reference value, and the yarn 10 can be evaluated with such a detection value as a reference. Therefore, an accurate yarn evaluation can be made by eliminating the influence of temperature drift and the like.
Now, a description will be made on a method for the
15 yarn monitoring control section 50 of the present embodiment to determine the evaluation reference value in various cases with reference to the graphs of FIGS. 6 to 8.
As described above, after the adjusting section 54
20 carries out the adjusting process, the acquiring section 55 iteratively acquires the detection value at appropriate time intervals until the introduction of the yarn 10 to the yarn path of the detection region 36 is detected. In the graph of FIG. 6, the horizontal axis indicates the time,
25 and the vertical axis indicates the detection value, and detection values (reference value candidate data) acquired at each timing from t1 to t15 are illustrated. The graph of FIG. 6 also illustrates the normal range threshold value and the yarn presence/absence determination threshold
30 value.
The acquiring section 55 repeats the acquisition of
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the detection value at a timing of t1, a timing of t2, and the like. In the example illustrated in FIG. 6, with more acquisition of the detection value, the detection value output by the sensor unit 35 becomes larger due to the 5 influence of the temperature drift. The detection value eventually becomes greater than the normal range threshold value at the acquisition timing of t14, which is also the case at t15. The detection values at both acquisition timings of t14 and t15 are smaller than the yarn
10 presence/absence determination threshold value.
Unless the detection value acquired by the acquiring section 55 becomes greater than or equal to the normal range threshold value, the yarn monitoring control section 50 stores, as needed, the detection value in the storage
15 section 57 as a candidate to be used for the calculation of the subsequent evaluation reference value. Therefore, the detection values acquired at the timings of t1 to t13 are stored in the storage section 57. The detection values acquired at the timings of t14 and t15 are greater than or
20 equal to the normal range threshold value, and thus are not stored in the storage section 57.
When the detection values continuously become greater than or equal to the normal range threshold value as in t14 and t15, the influence of the temperature drift
25 of an intolerable extent is assumed to have occurred. Therefore, if the detection value (detection value between normal range threshold value and yarn presence/absence determination threshold value) greater than or equal to the normal range threshold value and smaller than the yarn
30 presence/absence determination threshold value is continuously obtained two times, the yarn monitoring
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control section 50 carries out a control to again carry out the adjusting process by the adjusting section 54. Along with this, the measuring process is carried out again after the adjusting process, which is carried out again, is 5 completed.
Next, a description will be made on a case in which the detection value is caused to transition as in FIG. 7. In the example of FIG. 7, the detection value is in an increasing tendency from the timing of t1, but the influence
10 of the temperature drift substantially converges with time, and the detection values are stabilized at t11 to t13. However, the detection value at the timing of t14 becomes greater than the normal range threshold value, and the detection value further becomes greater than the yarn
15 presence/absence determination threshold value at t15.
In this case, the yarn monitoring control section 50 stores the detection values in the storage section 57 since the detection values acquired by the acquiring section 55 at the timings of t1 to t13 are smaller than the normal range
20 threshold value. On the other hand, the detection values acquired at the timings of t14 and t15 are greater than or equal to the normal range threshold value, and thus are not stored in the storage section 57.
Since the detection value obtained at the timing of
25 t15 is greater than the yarn presence/absence determination threshold value, the yarn presence/absence determining section 56 determine that the yarn 10 is introduced to the yarn path of the detection region 36 (yarn is present). In this case, the setting section 58 reads out from the storage
30 section 57 a predetermined number of most recent detection values acquired before the acquisition timing which is a
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predetermined number of times (three times in the present embodiment) back from the time at which determination is made that the yarn is present, and calculates an average value to set the obtained value as the evaluation reference 5 value. The correcting process can be carried out in this manner.
The case of FIG. 7 and the case of FIG. 6 are common in that the detection value exceeds the normal range threshold value for the first time at the timing of t14.
10 However, in the case of FIG. 7, the detection value at the next timing t15 exceeds the yarn presence/absence determination threshold value, and thus the determination is made that the yarn is present and the evaluation reference value is calculated, whereas in the case of FIG.
15 6, the detection value at the next timing t15 is between the normal range threshold value and the yarn presence/absence determination threshold value, and thus the process is carried out again from the adjusting process. Thus, in the present embodiment, when the detection value
20 exceeds the normal range threshold value, the subsequent process differs depending on whether or not the next detection value exceeds the yarn presence/absence determination threshold value.
As described above, in the yarn monitoring device 15
25 of the present embodiment, the evaluation reference value is not determined until determination is made by the yarn presence/absence determining section 56 that the yarn 10 is introduced to the yarn path of the detection region 36, and the acquiring section 55 continues to iteratively
30 acquire new detection values (reference value candidate data). Thus, the evaluation reference value can be defined
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using the detection value close to the timing at which the
yarn 10 is introduced to the detection region 36, so that
the influence of the temperature drift and the like can be
eliminated to a maximum extent.
5 The detection value, acquired at the timing which is
a predetermined number of times (three times) back from the timing at which determination is made that the yarn is present, is selected as the detection value for calculating the average of the evaluation reference values. This is
10 because the detection value immediately before the yarn 10 is introduced to the yarn path often varies due to the influence of the movement of the yarn 10. For example, as illustrated in FIG. 8, a transition is made such that the detection value is stabilized until the timing of t12, but
15 the detection value is once lowered at the timings of t13 and t14 until the yarn 10 enters the detection region 36 and moves towards the yarn path in the detection region 36 and finishes defining the position in the yarn path (accommodated in the yarn path), and the detection value
20 drastically increases at the timing of t15, which is immediately after the timing of t14, and becomes greater than the yarn presence/absence determination threshold value. The reason for such phenomenon is assumed to be because, in the course of introducing the yarn 10 to the
25 detection region 36, the light receiving section 42 is directly irradiated with light from the light projecting section 41 and also irradiated with light irradiated from the light projecting section 41 and reflected by the yarn 10, so that the detection value is once lowered. When the
30 detection value is caused to transition as illustrated in FIG. 8, the detection values at the timings of t13 and t14
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are stored in the storage section 57, but it is not appropriate to obtain the evaluation reference value using the detection value in variation. The setting section 58 of the present embodiment thus calculates the evaluation 5 reference value using the most recent detection values up to the acquisition timing which is three timings back from the timing at which determination is made that the yarn is present, as described above. Thus, the unstable behavior of the detection value at the timing too close to the moment
10 at which the yarn 10 takes the position in the yarn path can be prevented from being reflected on the evaluation reference value.
Next, a description will be made on a specific process carried out by the adjusting section 54, the acquiring
15 section 55, the yarn presence/absence determining section 56, the setting section 58, and the like of the yarn monitoring control section 50 with reference to the flowchart of FIG. 9.
The adjusting process, the measuring process, and the
20 like illustrated in FIG. 9 are carried out, other than at the power-on of the yarn monitoring device 15, each time the yarn 10 is disconnected for some reason and does not exist in the detection region 36 of the yarn monitoring device 15, and the yarn joining operation by the yarn
25 joining device 14 is carried out and the yarn 10 is introduced to the detection region 36 again. A case in which the yarn 10 is disconnected includes a case in which the yarn monitoring device 15 finds the yarn defect and cuts the yarn 10 by the cutter 16, a case in which the package
30 20 is fully wound and the yarn 10 is cut by the cutter 16 and the like, and a case in which the yarn breakage occurred.
25

Since the adjusting process and the measuring process are frequently carried out as described above, the yarn 10 can be stably monitored regardless of the change in surrounding environment, attachment of contamination to the light 5 projecting section 41, the light receiving section 42, and the like of the yarn monitoring device 15, and the like. If the process of FIG. 9 is started without the yarn 10 existing in the detection region 36 of the yarn monitoring device 15, the adjusting process by the
10 adjusting section 54 is first carried out, and the drive voltage of the light projecting section 41 in the sensor unit 35 is adjusted as described above (step S101). After the adjusting process is completed, the iterative acquiring processes (steps S102 to S106) of the detection values by
15 the acquiring section 55 are immediately started.
Specifically, the acquiring section 55 controls the sensor unit 35 so as to apply the drive voltage adjusted by the adjusting process on the light projecting section 41, and acquires the detection value actually output by the
20 sensor unit 35 (above-described measuring process, step S102). Thereafter, the yarn presence/absence determining section 56 determines whether or not the detection value acquired by the acquiring section 55 is greater than or equal to the yarn presence/absence determination threshold
25 value (step S103). When the detection value is smaller than the yarn presence/absence determination threshold value, whether or not the detection value is greater than or equal to the normal range threshold value is determined (step S104). When the detection value is smaller than the normal
30 range threshold value, the detection value is stored in the storage section 57 (S105), the process returns to step S102,
26

and the acquisition of the detection value is again repeated by the acquiring section 55.
When the detection value is greater than or equal to the normal range threshold value in the determination of 5 S104, whether or not the detection value acquired by the acquiring section 55 for the previous time is greater than or equal to the normal range threshold value is determined (step S106). When both of the detection value for this time and the detection value for the previous time are greater
10 than or equal to the normal range threshold value, the intolerable temperature drift is assumed to have occurred, and thus the process returns to step S101 and the process is carried out again from the adjusting process of the adjusting section 54. When the detection value for this
15 time is greater than or equal to the normal range threshold value but the detection value for the previous time is smaller than the normal range threshold value in the determination of S106, the process (step S105) of storing the detection value in the storage section 57 is skipped,
20 the process returns to S102, and the detection value is again acquired by the acquiring section 55.
When the detection value is greater than or equal to the yarn presence/absence determination threshold value in the determination of step S103, the setting process (step
25 S107) of the evaluation reference value by the setting section 58 is carried out. Specifically, the setting section 58 selects and reads out a predetermined number of most recent detection values acquired before the timing which is a predetermined number of times back from the
30 current time point out of a plurality of detection values stored in the order of time series in the storage section
27

57, and calculates an average value thereof to acquire a
new value of the evaluation reference value. The obtained
value of the evaluation reference value is stored in the
storage section 57.
5 Thereafter, the winding of the yarn 10 is started,
and the evaluating section 53 evaluates the yarn 10 travelling through the detection region 36 based on the new value of the evaluation reference value (step S108).
According to the above processes, the evaluating
10 section 53 of the yarn monitoring control section 50 can satisfactorily eliminate the influence of temperature drift and the like of the light projecting section 41, and can accurately evaluate the state of the yarn 10.
Next, a description will be made on the control of
15 the display lamp 46. The yarn monitoring control section 50 controls the display lamp 46 so as to be turned OFF during the adjusting process of step S101, and to be lighted in green during the measuring process of step S102 and the yarn monitoring of step S108. If abnormality occurs in the yarn
20 monitoring device 15, the yarn monitoring control section 50 carries out the control so that the display lamp 46 is lighted in red. In other words, in the yarn monitoring device 15 of the present embodiment, the display lamp 46 is controlled to have different display states during the
25 adjusting process and during the measuring process, i.e., turned OFF during the adjusting process, and lighted in green during the measuring process. The display lamp 46 is controlled such that the display state is the same, i.e., lighted in green, during monitoring of the yarn 10 and
30 during the measuring process. Furthermore, when abnormality occurs, the display lamp 46 is controlled so
28

as to be lighted in red, which is a display state different from any of the display state during the adjusting process (turned OFF), the measuring process (lighted in green), and the yarn monitoring (lighted in green). With the control 5 of the display lamp 46 as described above, the operator can easily recognize the status, and the like of the process being carried out in the yarn monitoring device 15.
In the yarn winding unit 1 of the present embodiment, the doffing operation of detaching the fully-wound package
10 20 and attaching an empty winding bobbin 21, as described above, may be carried out manually by the operator. The doffing operation includes carrying out an operation of pulling out the yarn 10 from the yarn supplying section (not illustrated), passing the yarn 10 through the detection
15 region 36 of the yarn monitoring device 15, fixing the end of the yarn 10 to the empty winding bobbin 21, and instructing the start of winding to the yarn winding unit 1.
However, when the operator carries out the doffing
20 operation, the instruction to start the winding on the yarn winding unit 1 may not be made for some reason although the setting of the yarn 10 to the yarn monitoring device 15 and the fixing of the yarn 10 to the winding bobbin 21 are completed, and the yarn 10 may be left for a long period
25 of time.
In this case, even though the evaluation reference value has been set using the detection value immediately before the yarn 10 is introduced to the detection region 36 of the yarn monitoring device 15, along with the doffing
30 operation, the yarn monitoring control section 50 may be in a situation where the monitoring of the yarn 10 cannot
29

be substantially started thereafter and a long period of time elapses. While being left untouched, a temperature drift too large to be tolerated may have occurred in the light projecting section 41, and thus even if the 5 instruction to start the winding is made by the operator thereafter, it is not appropriate to evaluate the yarn 10 using the evaluation reference value set for this time as is. Since a state where the yarn 10 is introduced to the detection region 36 of the yarn monitoring device 15 is
10 continued, the old set value of the evaluation reference value cannot be discarded to reset the setting.
To overcome such problems, the yarn monitoring control section 50 of the present embodiment is configured to determine whether or not the yarn 10 started travelling
15 by having the evaluating section 53 continuously monitor the detection value obtained from the sensor unit 35 after the yarn presence/absence determining section 56 determined that the yarn is present. The determination on whether the yarn 10 is travelling or is stationary
20 (hereinafter, sometimes referred to as travelling determination) is made, for example, based on the magnitude of the variation of the detection value obtained from the sensor unit 35.
The stationary time counting section 59 of the yarn
25 monitoring control section 50 is configured to increment a count value indicating the elapsed time in the stationary state by one when the yarn 10 is determined to be stationary as a result of the travelling determination carried out by the evaluating section 53. The yarn monitoring control
30 section 50 carries out a control to operate the cutter 16 to cut the yarn 10 at the timing (timing of t95 in the example
30

illustrated in FIG. 10) at which the count value reached a predetermined value.
Thus, if a state where the yarn 10 is exists in the detection region 36 but the start of travelling is not 5 detected is continued for a prescribed time or longer, the yarn 10 is forcibly cut, and the operator again carries out the doffing operation from the state where the yarn 10 is removed from the detection region 36 of the yarn monitoring device 15. Therefore, the opportunity for the yarn
10 monitoring control section 50 (setting section 58) to reset the evaluation reference value can be ensured, and the accurate monitoring of the state of the yarn 10 can be realized.
As described above, the yarn monitoring device 15 of
15 the present embodiment includes the sensor unit 35, the acquiring section 55, the setting section 58, and the evaluating section 53. The sensor unit 35 outputs a detection value corresponding to the presence/absence of the yarn 10 in the detection region 36 or the state of the
20 yarn 10. The acquiring section 55 acquires the detection value in a state where the yarn 10 does not exist in the detection region. The setting section 58 sets the evaluation reference value to be used to evaluate the state of the yarn 10 based on at least one of a plurality of
25 detection values obtained by repeating the acquisition of the detection value by the acquiring section 55 until the yarn 10 is introduced to the detection region 36. The evaluating section 53 evaluates the state of the yarn 10 based on the evaluation reference value set by the setting
30 section 58.
Thus, by continuously and iteratively acquiring the
31

detection value, the detection value immediately before the yarn 10 is introduced to the detection region 36 can be obtained, for example. Thus, the influence of the temperature drift and the like is alleviated by defining 5 the evaluation reference value using the detection value acquired at the relevant timing. Therefore, the state of the yarn 10 can be accurately detected.
The yarn monitoring device 15 of the present embodiment includes the yarn presence/absence determining
10 section 56 adapted to determine whether or not the yarn 10 is introduced to the detection region 36. The setting section 58 sets the evaluation reference value based on the detection value acquired by the acquiring section 55 before the yarn presence/absence determining section 56
15 determines that the yarn 10 is introduced into the detection region 36.
In other words, even if the detection value is acquired after the yarn 10 is introduced into the detection region 36, such a detection value cannot be used as the
20 reference value, and thus an appropriate evaluation reference value can be set by not using such a detection value.
Furthermore, in the yarn monitoring device 15 of the present embodiment, the sensor unit 35 includes the light
25 projecting section 41 adapted to project light into a space through which the yarn 10 travels, and the light receiving section 42 adapted to receive the light projected by the light projecting section 41 and to output an electrical signal corresponding to the light receiving amount. The
30 yarn monitoring device 15 includes the adjusting section 54. The adjusting section 54 carries out the adjusting
32

process of adjusting the light projecting amount of the
light projecting section 41 such that the detection value
in the state where the yarn 10 does not exist coincides with
a value (adjustment reference value) defined in advance.
5 In other words, the light projecting amount of the
light projecting section 41 and the light receiving amount of the light receiving section 42 may possibly vary due to the change in environment such as the temperature drift. Therefore, the reference value can be adjusted in
10 accordance with the change in environment by carrying out the adjusting process, and the evaluation accuracy of the state of the yarn 10 can be stabilized.
The yarn monitoring device 15 of the present embodiment includes the storage section 57 adapted to store
15 the normal range threshold value and the yarn presence/absence determination threshold value. The normal range threshold value indicates a predetermined range with respect to the detection value in a state where the yarn 10 does not exist in the detection region 36. The
20 yarn presence/absence determination threshold value is a threshold value for determining whether or not the yarn 10 exists in the detection region 36, and is a threshold value greater than the normal range threshold value. When the acquiring section 55 acquires the detection value greater
25 than or equal to the normal range threshold value and smaller than the yarn presence/absence determination threshold value immediately after acquiring the detection value greater than or equal to the normal range threshold value, the adjusting section 54 carries out the adjusting
30 process.
In other words, when the yarn 10 is introduced to the
33

detection region 36, the detection value output by the sensor unit 35 usually greatly varies, and the acquiring section 55 may acquire the beginning of such variation as the detection value. If the influence of the temperature 5 drift is too large to be tolerated, the adjusting process is preferably carried out to adapt to the change in environment. In this regard, according to the configuration of the present embodiment, in the course of the acquiring section 55 acquiring the detection value a
10 plurality of times, if the detection value greater than or equal to the normal range threshold value is obtained, and immediately thereafter, the detection value greater than or equal to the normal range threshold value and smaller than the yarn detection determination threshold value is
15 obtained, as illustrated in t14 and t15 of FIG. 6, the detection value is assumed to have increased by the influence of temperature drift, and hence the adjusting process is carried out. Thus, the adjusting process is carried out only when necessary, whereby the influence of
20 the temperature drift and the like can be accurately eliminated without lowering the efficiency, and the state can be returned to the state where the state of the yarn 10 can be accurately evaluated by the evaluating section 53.
25 In the yarn monitoring device 15 of the present
embodiment, when the acquiring section 55 acquires the detection value greater than or equal to the normal range threshold value and immediately thereafter, acquires the detection value greater than or equal to the yarn
30 presence/absence determination threshold value, the yarn presence/absence determining section 56 determines that
34

the yarn 10 is located in the detection region 36.
Thus, whether or not the yarn 10 is introduced to the detection region 36 can be determined with a simple process while clearly distinguishing from a case in which the 5 detection value becomes greater than or equal to the normal range threshold value due to the influence of the temperature drift, and the like.
Furthermore, in the yarn monitoring device 15 of the present embodiment, the detection value acquired by the
10 acquiring section 55 is stored in the storage section 57. The setting section 58 sets the evaluation reference value based on the detection value stored in the storage section 57. However, if the detection value acquired by the acquiring section 55 becomes greater than or equal to the
15 normal range threshold value, the storing of the detection value to the storage section 57 is stopped.
In other words, if the value outside a range, which the value is to usually take, is acquired as the detection value, it is not appropriate to use such a detection value
20 for the calculation of the evaluation reference value. In this regard, the detection value greater than or equal to the normal range threshold value can be reliably prevented from being used for the evaluation reference value by preventing the detection value greater than or equal to the
25 normal range threshold value from being stored in the storage section 57.
Moreover, in the yarn monitoring device 15 of the present embodiment, when the yarn presence/absence determining section 56 determines that the yarn 10 is
30 introduced to the detection region 36, the setting section 58 sets the evaluation reference value based on the
35

detection value obtained before the detection value acquisition timing which is a predetermined number of times before the relevant determination.
In other words, in the course of introducing the yarn 5 10 to the detection region 36, the detection value output by the sensor unit 35 may show an unstable behavior. In this regard, in the present embodiment, by adopting the detection value before a time point which is a predetermined number of times back from the time point at which
10 determination is made that the yarn 10 is introduced to the detection region 36, the evaluation reference value can be set using an appropriate detection value from which the above-described influence is eliminated.
In the yarn monitoring device 15 of the present
15 embodiment, the setting section 58 sets, as the evaluation reference value, the average value of the plurality of detection values acquired by the acquiring section 55.
Thus, the variation of the individual detection value by various types of noise is prevented from being reflected
20 on the evaluation reference value, and the evaluation reference value can be appropriately defined.
The yarn monitoring device 15 of the present embodiment includes the stationary time counting section 59. The stationary time counting section 59 counts the
25 elapsed time in a state where the yarn 10 is stationary in the detection region 36. When the elapsed time counted by the stationary time counting section 59 exceeds a predetermined time, the yarn monitoring device 15 cuts the yarn by the cutter 16 arranged in the yarn monitoring device
30 15.
In other words, for example, a long period of time
36

may elapse with the yarn 10 existing in the detection region 36 such as when the doffing operation is manually carried out, and in this case, the influence of the temperature drift and the like may become a problem. Even if the set 5 value of the old evaluation reference value is discarded to reset the evaluation reference value, the detection value in a state where the yarn 10 does not exist cannot be acquired by the acquiring section 55 since the yarn 10 already exists in the detection region 36. Therefore, the
10 detection value in a state where the yarn 10 does not exist in the detection region 36 is reacquired by forcibly cutting the yarn 10, so that the evaluation reference value can be reset.
Next, a description will be made on an alternative
15 embodiment of the above-described embodiment. In the description of this alternative embodiment, the members same as or similar to those in the above-described embodiment are denoted with the same reference numerals in the drawings, and the description thereof may be omitted.
20 In the above-described embodiment, the acquiring
section 55 iteratively acquires the detection value until the yarn presence/absence determining section 56 determines that the yarn 10 exists in the detection region 36. In this alternative embodiment, a signal related to
25 the time (hereinafter sometimes referred to as yarn introducing timing) at which the yarn 10 is introduced to the detection region 36 is provided from the unit control section 30 with respect to the yarn monitoring control section 50.
30 In this alternative embodiment, the signal related
to the yarn introducing timing is specifically a signal
37

indicating a timing at which the first yarn catching device 12 and the second yarn catching device 13 guides the yarn 10 to the yarn joining device 14. For example, the first yarn catching device 12 and the second yarn catching device 5 13 are swung as illustrated in FIGS. 1 to 3 to guide the yarn 10 to the yarn joining device 14, but the signal representing the timing to start the swinging is provided from the unit control section 30 to the yarn monitoring control section 50. Normally, the timing at which the yarn
10 10 is introduced to the detection region 36 of the yarn monitoring device 15 is after elapse of a prescribed time from the start of swinging of the first yarn catching device 12 and the second yarn catching device 13. Therefore, the yarn monitoring control section 50 can predict the yarn
15 introducing timing by calculation.
The yarn monitoring control section 50 determines the timing slightly before the yarn introducing timing as the acquisition timing of the detection value. After the completion of the adjusting process by the adjusting
20 section 54, the process is in standby until the acquisition timing, and when the acquisition timing arrives, the acquiring section 55 acquires the detection value output by the sensor unit 35 for a predetermined number of times. The setting section 58 sets the average value of the
25 detection values as the evaluation reference value.
Thereafter, the detection value output by the sensor unit 35 is acquired immediately after the predicted yarn introducing timing, and such detection value is used for the determination of the presence/absence of the yarn 10
30 by the yarn presence/absence determining section 56. Whether or not the yarn 10 is introduced to the detection
38

region 36 as predicted can be checked. If the travelling of the yarn 10 is started, the evaluating section 53 evaluates the state of the yarn 10. When a long period of time has elapsed with the yarn 10 remaining stationary, the 5 yarn 10 is forcibly cut by the cutter 16, similarly to the above-described embodiment.
According to the above configuration, the detection value immediately before the yarn 10 is introduced to the detection region 36 is acquired, and the evaluation
10 reference value can be set.
As described above, in the yarn monitoring device 15 of this alternative embodiment, the setting section 58 acquires, from outside, a time at which the yarn 10 is introduced to the detection region 36, and sets the
15 evaluation reference value based on a plurality of detection values acquired by the acquiring section 55 at a timing determined based on the acquired time.
According to such a configuration, the acquiring section 55 can obtain the detection value output by the
20 sensor unit 35 immediately before the yarn 10 is introduced to the detection region 36. Therefore, by defining the evaluation reference value using the detection value, the influence of the temperature drift and the like can be reduced and the state of the yarn 10 can be accurately
25 evaluated.
The yarn winding machine (yarn winding unit 1) in this alternative embodiment includes the yarn monitoring device 15, the winding section 18, the yarn joining device 14, the first yarn catching device 12, and the second yarn catching
30 device 13. The winding section 18 winds the yarn 10 to form the package 20. The yarn joining device 14 carries out the
39

yarn joining operation. The first yarn catching device 12 and the second yarn catching device 13 guide the yarn 10 to the yarn joining device 14. The acquiring section 55 acquires the detection value at the timing based on the 5 timing at which the first yarn catching device 12 and the second yarn catching device 13 guide the yarn 10 to the yarn joining device 14. The setting section 58 sets the evaluation reference value based on the detection value measured by the acquiring section 55.
10 In other words, the yarn 10 does not exist in the
detection region 36 of the yarn monitoring device 15 in a state where the yarn 10 is disconnected, but the yarn 10 is introduced to the detection region 36 when the yarn joining operation is carried out by the yarn joining device
15 14. Therefore, the detection value is acquired at the timing determined based on the timing at which the first yarn catching device 12 and the second yarn catching device 13 guide the yarn 10 to the yarn joining device 14, so that the detection value immediately before the yarn 10 is
20 introduced to the detection region 36 is rationally obtained and the evaluation reference value can be set. As a result, the influence of the temperature drift and the like can be effectively eliminated. Furthermore, the number of acquisitions of the detection value can be reduced,
25 so that the load of the computer can be reduced.
The preferred embodiments and the alternative embodiment of the present invention have been described above, but the above-described configurations may be modified as below.
30 In the embodiment and the alternative embodiment
described above, the evaluation reference value is
40

calculated by obtaining an average of the detection value acquired a plurality of times. However, the present invention is not limited thereto, and the setting section 58 may set the detection value acquired only once as is, 5 as the evaluation reference value.
In the above-described embodiment, if the detection value greater than or equal to the normal range threshold value and smaller than the yarn presence/absence determination threshold value is acquired even once
10 immediately after the detection value greater than or equal to the normal range threshold value (smaller than yarn presence/absence determination threshold value) is acquired, the process is carried out again from the adjusting process. However, the condition of again
15 carrying out the adjusting process may be when the detection value greater than or equal to the normal range threshold value and smaller than the yarn presence/absence determination threshold value is acquired for a predetermined number of times, which is two or more times,
20 immediately after the detection value greater than or equal to the normal range threshold value is acquired.
In the above-described embodiment, the detection value before the acquisition timing, which is three times back from the timing at which determination is made that
25 the yarn is present by the yarn presence/absence determining section 56, is used for the calculation of the evaluation reference value. However, for the number of timings to go back for the acquisition timing is not limited to three times, and may be appropriately defined in view
30 of the time interval for acquiring the detection value, and the like.
41

In the above-described alternative embodiment, the acquisition of the detection value by the acquiring section 55 is carried out at the timing determined based on the external information. However, in the configuration of 5 the alternative embodiment as well, the acquiring section 55 may iteratively acquire the detection value from immediately after the adjusting process by the adjusting section 54, similarly to the above-described embodiment. In this case, similarly to the above-described embodiment,
10 whether or not the detection value is greater than or equal to the normal range threshold value is checked in real time so as to enable a control of performing the adjusting process again when the influence of the intolerable temperature drift occurs.
15 In the embodiment and the alternative embodiment
described above, the yarn monitoring device 15 includes the optical sensor unit 35 having the light projecting section 41 and the light receiving section 42. Alternatively, the yarn monitoring device may include a capacitance sensor
20 unit. The optical type sensor unit and the capacitance type sensor unit are similar in that the detection value corresponding to the state of the yarn 10 (e.g., cross-sectional shape or amount of fibers) existing in the detection region 36 is output. However, the capacitance
25 yarn monitoring device is more greatly affected by the humidity change than the temperature drift due to its properties. In this regard, the state of the yarn 10 can be monitored while effectively eliminating the influence of humidity change by setting the evaluation reference
30 value using the detection value immediately before the introduction of the yarn 10 as in the embodiment and the
42

above-described alternative embodiment.
In the above-described embodiment, the yarn monitoring device 15 has a configuration of incorporating the cutter 16. However, the present invention is not 5 limited thereto, and the cutter may be arranged outside the yarn monitoring device 15, and the cutter may be controlled by the unit control section 30. In this case, the yarn monitoring control section 50 outputs the yarn cutting signal to the unit control section 30, and the unit control
10 section 30 drives the cutter based on the yarn cutting signal. When applying the present invention to the spinning machine serving as the yarn winding machine, the cutter is not particularly arranged, and the spinning operation of the spinning device is stopped to cut the yarn
15 10 (i.e., spinning device also serves as cutting device). Furthermore, the yarn monitoring device 15 is configured to cut the yarn 10 when the yarn defect is detected, by the cutter 16 or other cutting devices, to remove the yarn defect, but the yarn monitoring device of the present
20 invention may be a device that only monitors the state of the yarn 10 without cutting the yarn 10 by the cutter 16 or other cutting devices.
A display illustrating the status of the yarn monitoring device 15 may include, for example, a liquid
25 crystal display and the like in place of the display lamp 46 including two-color LED.
In the above-described embodiment, the yarn 10 is irradiated with light from the light projecting section 41, and the evaluation reference value is set using the light
30 receiving section 42 that receives the transmitted light, which is the light that passed the yarn 10. However, the
43

yarn 10 may be irradiated with light from the light projecting section 41, and the evaluation reference value may be set using the light receiving section that receives the reflected light, which is the light reflected by the 5 yarn 10.
The configuration of the present invention is not limited to the automatic winder, and can be applied to other types of yarn winding machines such as, for example, a spinning machine as described above. When the
10 configuration of the present invention is applied to the spinning machine, for example, the pneumatic spinning device corresponds to the yarn supplying section. In the spinning machine, one (one set) of the yarn joining device and the yarn catching and guiding device is preferably
15 provided with respect to a plurality of yarn winding units. In other words, one yarn joining cart mounted with the yarn joining device and the yarn catching and guiding device is provided with respect to a plurality of yarn winding units, and is preferably configured to move along the direction
20 in which the plurality of yarn winding units are arranged. However, a configuration of the spinning machine including one yarn joining device for one yarn winding unit may also be adopted.
According to a first aspect of the present invention,
25 a yarn monitoring device having the following configuration is provided. Specifically, the yarn monitoring device includes a detecting section, an acquiring section, a setting section, and an evaluating section. The detecting section is adapted to output a detection value
30 corresponding to presence/absence of a yarn in a detection region and corresponding to a state of a yarn when the yarn
44

exists in the detection region. The acquiring section is adapted to acquire the detection value in a state where the yarn does not exist in the detection region. The setting section is adapted to set an evaluation reference value to 5 be used in evaluating the state of the yarn. The evaluating section is adapted to evaluate the state of the yarn based on the evaluation reference value set by the setting section and the detection value output by the detecting section. The setting section sets the evaluation reference value
10 based on at least one of a plurality of the detection values acquired by repeating the acquisition of the detection value by the acquiring section until the yarn is introduced to the detection region. Alternatively, the setting section sets the evaluation reference value based on the
15 one or the plurality of detection values acquired by the acquiring section at a predetermined timing. The predetermined timing is determined based on a time acquired by the acquiring section from outside, the time at which the yarn is introduced to the detection region.
20 Thus, for example, the detection value output by the
detecting section immediately before the yarn is introduced to the detection region can be obtained by continuously and iteratively acquiring the detection value output by the detecting section. Furthermore, the time at which the yarn
25 is introduced to the detection region may be acquired from outside and the detection value may be acquired at an appropriate timing based on the acquired time, so that the detection value output by the detecting section immediately before the yarn is introduced to the detection region is
30 similarly obtained. Thus, the influence of the change in environment (temperature drift, change in humidity,
45

attachment of contamination, and the like) is alleviated by defining the evaluation reference value using the detection value acquired at the relevant timing. Therefore, the state of the yarn can be accurately detected.
The above-described yarn monitoring device preferably has the following configuration. Specifically, the yarn monitoring device includes a yarn presence/absence determining section. The yarn presence/absence determining section is adapted to determine whether or not the yarn exists at a predetermined position of the detection region and whether or not the yarn is introduced to the predetermined position of the detection region. The setting section sets the evaluation reference value based on the detection value acquired by the acquiring section before the yarn presence/absence determining section determines that the yarn is introduced to the detection region.
In other words, even if the detection value is acquired after the yarn is introduced to the detection region, such detection value cannot be used as a candidate for the reference value, and thus an appropriate evaluation reference value can be set by not using such detection value.
The above-described yarn monitoring device preferably has the following configuration. Specifically, the detecting section includes a light projecting section adapted to project light on the detection region, and a light receiving section adapted to receive the light projected by the light projecting section and output an electrical signal corresponding to a light receiving amount. The yarn monitoring device further includes an adjusting
46

section adapted to carry out an adjusting process of adjusting a light projecting amount of the light projecting section such that the detection value when the yarn does not exist in the detection region coincides with a value defined in advance.
In other words, the light projecting amount of the light projecting section and the light receiving amount of the light receiving section may possibly vary due to the change in environment. Therefore, the light projecting amount can be actively adjusted in accordance with the change in environment by carrying out the adjusting process, and the evaluation accuracy of the state of the yarn can be stabilized.
The above-described yarn monitoring device preferably has the following configuration. Specifically, the yarn monitoring device includes a storage section for storing a first threshold value and a second threshold value . The first threshold value is a value for defining one of boundaries of a predetermined range with respect to the detection value in a state where the yarn does not exist in the detection region. The second threshold value is a threshold value for determining whether or not the yarn exists at the predetermined position of the detection region, the second threshold value being a value outside the predetermined range and a value exceeding the first threshold value. When the acquiring section acquires the detection value between the first threshold value and the second threshold value for a predetermined number of times, which is one or more times, immediately after acquiring the detection value exceeding the first threshold value, the adjusting section carries out the adjusting process.
47

In other words, when the yarn is introduced to the detection region, the detection value output by the detecting unit usually greatly varies, and the acquiring section may acquire the beginning of such variation as the detection value. If the influence of the temperature drift is too large to be tolerated, the adjusting process is preferably carried out to adapt to the change in environment In this regard, according to the above-described configuration, in the course of the acquiring section acquiring the detection value a plurality of times, if the detection value exceeding the first threshold value is obtained, and thereafter, the detection value between the first threshold value and the second threshold value is obtained, the detection value is assumed to have increased by the influence of temperature drift, and hence the adjusting process is carried out. Thus, the adjusting process is carried out only when necessary, whereby the influence of the temperature drift can be accurately eliminated without lowering the efficiency, and the evaluation on the state of the yarn by the evaluating section can be returned to a state where the evaluation can be accurately carried out.
In the above-described yarn monitoring device, when the acquiring section acquires the detection value exceeding the second threshold value immediately after acquiring the detection value exceeding the first threshold value, the yarn presence/absence determining section preferably determines that the yarn is introduced to the detection region.
Thus, whether or not the yarn is introduced to the detection region can be determined with a simple process
48

while clearly distinguishing from a case in which the detection value exceeds the first threshold value due to the influence of the temperature drift and the like.
The above-described yarn monitoring device preferably has the following configuration. Specifically, the detection value acquired by the acquiring section is stored in the storage section. The setting section sets the evaluation reference value based on the detection value stored in the storage section when the yarn does not exist in the detection region. When the detection value is a value outside the predetermined range when the yarn does not exist in the detection region, the detection value is not stored in the storage section.
In other words, if the value outside a normal range, which the value is to usually take, is acquired as the detection value, it is not appropriate to use such a detection value for the calculation of the evaluation reference value. In this regard, according to the above-described configuration, the detection value outside the predetermined range is prevented from being stored in the storage section, so that the detection value outside the normal range can be reliably prevented from being used for the calculation of the evaluation reference value.
In the above-described yarn monitoring device, the setting section preferably sets the evaluation reference value based on the detection value obtained before a detection value acquisition timing which is a predetermined number of times before a time point at which the yarn presence/absence determining section determines that the yarn is introduced to the predetermined position of the detection region.
49

In other words, in the course of introducing the yarn to the detection region, the detection value output by the detecting section may show an unstable behavior. In this regard, in the above-described configuration, by adopting the detection value before a time point which is a predetermined number of times back from the time point at which determination is made that the yarn is introduced to the detection region, the evaluation reference value can be set using an appropriate detection value from which the above-described influence is eliminated.
In the above-described yarn monitoring device, the setting section preferably sets, as the evaluation reference value, an average value of the plurality of detection values acquired by the acquiring section.
Thus, the variation of the individual detection value by various types of noise is prevented from being excessively reflected on the evaluation reference value, and the evaluation reference value can be appropriately defined.
The above-described yarn monitoring device preferably has the following configuration. Specifically, the yarn monitoring device includes a counting section adapted to count an elapsed time in a state where the yarn is stationary in the detection region. When the count of the counting section exceeds a predetermined time, the yarn monitoring device cuts the yarn by a cutting device arranged in the yarn monitoring device or an external cutting device .
In other words, for example, when the doffing operation is carried out manually, a long period of time may elapse with the yarn existing in the detection region and without the yarn travelling. In this case, the
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influence of the temperature drift and the like may become a problem. Meanwhile, even if the set value of the old evaluation reference value is discarded to reset the evaluation reference value, the detection value in a state where the yarn does not exist cannot be acquired by the acquiring section since the yarn already exists in the detection region. In this regard, the detection value in a state where the yarn does not exist in the detection region is reacquired by forcibly cutting the yarn as described above, and the evaluation reference value can be reset. According to a second aspect of the present invention, a yarn winding machine having the following configuration is provided. Specifically, the yarn winding machine includes the yarn monitoring device, a winding section, a yarn joining device, and a yarn catching and guiding device. The winding section is adapted to wind the yarn to form a package. The yarn joining device is adapted to carry out a yarn joining operation. The yarn catching and guiding device is adapted to guide the yarn to the yarn joining device. The acquiring section acquires one or a plurality of the detection values at a timing determined based on a timing at which the yarn catching and guiding device guides the yarn to the yarn joining device. The setting section sets, as the evaluation reference value, the one detection value or an average value of the plurality of detection values acquired by the acquiring section at the determined timing.
In other words, the yarn does not exist in the detection region of the yarn monitoring device in a state where the yarn is disconnected, but the yarn is introduced to the detection region when the yarn joining operation is
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carried out by the yarn joining device. Therefore, the detection value is acquired at the timing determined based on the timing at which the yarn catching and guiding device guides the yarn to the yarn joining device, so that the detection value immediately before the yarn is introduced to the detection region can be rationally obtained. Furthermore, the number of acquisitions of the detection value can be reduced.
According to a third aspect of the present invention, a yarn monitoring method having the following configuration is provided. Specifically, the yarn monitoring method comprises detecting a value corresponding to presence/absence of a yarn in a detection region and corresponding to a state of the yarn when the yarn exists in the detection region, acquiring the detection value when the yarn does not exist in the detection region, setting an evaluation reference value to be used in evaluating the state of the yarn, and evaluating the state of the yarn based on the evaluation reference value set by the setting section and the detection value output by the detecting section, and is characterized by setting the evaluation reference value based on at least one of a plurality of the detection values acquired by repeating the acquisition of the detection value until the yarn is introduced into the detection region.

We claim:
1. A yarn monitoring device comprising:
a detecting section adapted to output a detection value corresponding to presence/absence of a yarn in a detection region and corresponding to a state of the yarn when the yarn exists in the detection region;
an acquiring section adapted to acquire the detection value when the yarn does not exist in the detection region;
a setting section adapted to set an evaluation reference value to be used in evaluating the state of the yarn; and
an evaluating section adapted to evaluate the state of the yarn based on the evaluation reference value set by the setting section and the detection value output by the detecting section, characterized in that
the setting section sets the evaluation reference value based on at least one of a plurality of the detection values acquired by repeating the acquisition of the detection value by the acquiring section until the yarn is introduced to the detection region.
2. The yarn monitoring device according to claim 1,
characterized by further comprising:
a yarn presence/absence determining section adapted to determine whether or not the yarn exists at a predetermined position of the detection region and whether or not the yarn is introduced to the predetermined position of the detection region,
wherein the setting section sets the evaluation reference value based on the detection value acquired by
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the acquiring section before the yarn presence/absence determining section determines that the yarn is introduced to the predetermined position.
3. The yarn monitoring device according to claim 2,
characterized in that
the detecting section includes a light projecting section adapted to project light on the detection region, and a light receiving section adapted to receive the light projected by the light projecting section and to output an electrical signal corresponding to a light receiving amount, and
the yarn monitoring device further includes an adjusting section adapted to carry out an adjusting process of adjusting a light projecting amount of the light projecting section such that the detection value when the yarn does not exist in the detection region corresponds to a value defined in advance.
4. The yarn monitoring device according to claim 3,
characterized by further comprising:
a storage section adapted to store a first threshold value for defining one of boundaries of a predetermined range with respect to the detection value when the yarn does not exist in the detection region, and a second threshold value for determining whether or not the yarn exists at the predetermined position of the detection region, the second threshold value being a value outside the predetermined range and a value exceeding the first threshold value,
wherein when the acquiring section acquires the detection value between the first threshold value and the
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second threshold value for a predetermined number of times, which is one or more times, immediately after acquiring the detection value exceeding the first threshold value, the adjusting section carries out the adjusting process.
5. The yarn monitoring device according to claim 4,
characterized in that
when the acquiring section acquires the detection value exceeding the second threshold value immediately after acquiring the detection value exceeding the first threshold value, the yarn presence/absence determining section determines that the yarn is introduced to the predetermined position of the detection region.
6. The yarn monitoring device according to claim 4
or 5, characterized in that
the detection value acquired by the acquiring section is stored in the storage section,
the setting section sets the evaluation reference value based on the detection value stored in the storage section when the yarn does not exist in the detection region, and
when the detection value is a value outside the predetermined range when the yarn does not exist in the detection region, the detection value is not stored in the storage section.
7 . The yarn monitoring device according to any one of claims 2 to 6, characterized in that
the setting section sets the evaluation reference value based on the detection value obtained before a
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detection value acquisition timing which is a predetermined number of times before a time point at which the yarn presence/absence determining section determines that the yarn is introduced to the predetermined position of the detection region.
8 . The yarn monitoring device according to any one of claims 2 to 7, characterized in that
the setting section sets an average value of the plurality of detection values acquired by the acquiring section for the evaluation reference value.
9. The yarn monitoring device according to any one
of claims 1 to 8, characterized by further comprising:
a counting section adapted to count an elapsed time in a state where the yarn is stationary in the detection region,
wherein when the count of the counting section exceeds a predetermined time, the yarn is cut by a cutting device arranged in the yarn monitoring device or an external cutting device.
10. A yarn monitoring device comprising:
a detecting section adapted to output a detection value corresponding to presence/absence of a yarn in the detection region and corresponding to a state of the yarn when the yarn exists in the detection region;
an acquiring section adapted to acquire the detection value when the yarn does not exist in the detection region;
a setting section adapted to set an evaluation reference value to be used in evaluating the state of the
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yarn; and
an evaluating section adapted to evaluate the state of the yarn based on the evaluation reference value set by the setting section and the detection value output by the detecting section, characterized in that
the acquiring section acquires, from outside, a time at which the yarn is introduced to the detection region, and acquires one or a plurality of the detection values at a timing determined based on the acquired time, and
the setting section sets the evaluation reference value based on the one or the plurality of detection values acquired by the acquiring section at the determined timing.
11. A yarn winding machine characterized by comprising:
the yarn monitoring device according to claim 10;
a winding section adapted to wind a yarn to form a package;
a yarn joining device adapted to carry out a yarn joining operation; and
a yarn catching and guiding device adapted to guide the yarn to the yarn joining device,
wherein the acquiring section acquires one or plurality of the detection values at a timing determined based on a timing at which the yarn catching and guiding device guides the yarn to the yarn joining device, and
the setting section sets, as the evaluation reference value, the one detection value or an average value of the plurality of detection values acquired by the acquiring section at the determined timing.
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12. A yarn winding machine characterized by
comprising:
in order from upstream in a travelling direction of a yarn,
a yarn supplying section adapted to supply the yarn;
the yarn monitoring device according to any one of claims 1 to 10; and
a winding section adapted to wind a yarn to form a package.
13. A yarn monitoring method comprising:
detecting a value corresponding to presence/absence
of a yarn in a detection region and corresponding to a state of the yarn when the yarn exists in the detection region;
acquiring the detection value when the yarn does not exist in the detection region;
setting an evaluation reference value to be used in evaluating the state of the yarn; and
evaluating the state of the yarn based on the evaluation reference value set by the setting section and the detection value output by the detecting section, characterized by
setting the evaluation reference value based on at least one of a plurality of the detection values acquired by repeating the acquisition of the detection value until the yarn is introduced into the detection region.