FORM -2
THE PATENTS ACT, 1970 (39 of 1970)
COMPLETE SPECIFICATION
(See Section 10:BULE 13)

HINDUSTAN LEVER LIMITED, a company incorporated under the Indian Companies Act, 1913 and having its registered office at Hindustan Lever House, 165/166, Backbay Reclamation, Mumbai -400 020, Maharashtra, India
The following specification particularly describes the nature of the invention and the manner in which it is to be performed.

19-01-2004/24-02-2005

FIELD OF THE INVENTION
The present invention relates to a densitometer and in particular to a system for fast and reliable measurement of bulk density of any substance in liquid or solid form such as tea or other materials in the form of powders or grains or fine dust. The system is particularly suitable for automated fast and reliable measurement, recording, and storing of bulk density values of various substances such as tea which require fast and accurate large scale evaluation of density based characteristics of various varieties of tea for regular trading and business purposes.
BACKGROUND ART
It is known that granular and powder products need to be traded based on weight rather than volume and accordingly various devices/gadgets have been developed from time to time to ascertain the weight of such dry products to facilitate determining its character and values. Considering that the weights of products are also related to the density of the product various density measuring sensors and devices to measure density of dry products such as salts, flour or cement are available.
US 4624129 discloses a device for installation on the auger filler cone of dry products dispensing equipment which comprises one or more ultrasonic resonators arranged so as to measure the acoustic impedance of the product within the auger filler cone without interfering with the flow of the auger product. The acoustic impedance can be calibrated to give a density measurement. The device is particular well suited for measuring of the density of a dry product in the dispensing equipment used in the packaging industry, where a specified amount by weight must be dispensed into containers. Since an auger type filling machine dispenses a precise volume for each degree of rotational movement of the auger constant monitoring of the density of the product within the auger cone allows the weight of the dispensed product to be rapidly and accurately determined during the filling process.
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US 5,900,535 discloses an ultrasonic fuel-gauging system having a tank with several ultrasonic probes having reflector spaced along their length. A vibrating cylinder densitometer is located at the bottom of the tank and provides an output to a control unit representative of fuel density at that location. The control unit calculates the speed of sound reflected from the reflector closest to the densitometer and uses this and the density measurement to calculate a fuel constant. The control unit calculates the density of fuel at different heights from the fuel constant and speed of sound measurements from other reflectors. From these density measurements the control unit calculates mean density and fuel mass.
US 6,053,041 discloses non invasive method for determing the liquid level and density inside of a container having arbitrary dimension and shape. By generating flexural acoustic wave in the container shell and measuring the phase difference of the detected flexural wave from that of the originally wave a small distance from the generated wave, while moving the generation and detection means through the liquid/vapor interface, this interphase can be detected. Both the wave generation and wave detection may be achieved by transducers on the surface of the container. A change in the phase difference over the outer surface of the vessel signifies that a liquid/vapor interface has been crossed while the magnitude of the phase difference can be related to fluid density immediately opposite the measurement position on the surface of the vessel.
The above would go to show that the use of ultrasonic sensors or acoustic waves for various applications including measuring of the weight and density of solid or liquid substances have been in use and existing in the art, however, all such known devices and their uses are specific application based and suggest mechanisms of measurement involving gadgets and their arrangement which are specifically developed for the desired end-use/application targeted.
In the tea industry, some of the most important parameters that decide the value or quality of the tea in the market include tea-leaf/dust appearance, their
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size, bulk density, tea-liquor color, aroma and taste. Normally, a trained tea taster is involved in ascertaining the character and quality of the tea by assigning scores to the various tea samples for all its related characteristics/properties. Usually, such process is carried out manually and to facilitate the same tea boys are employed for preparing tea to be tasted while tea tasters are appointed to taste the tea process to note down the relevant values. Thus such evaluation of character/quality of tea is presently completely a manual process requiring involving lot of time and man-hours.
As regards the measuring of the tea bulk density is concerned, the current practice involving manual intervention requires initial weighing of the sample, then using a stroking machine to level the tea dust and then the height of the content is manually measured for each tea sample to calculate therefrom the density of the various varieties of tea. On an average following such extensive manual method only about 200 varieties of tea bulk density measurement are carried out per day.
It is thus experienced that the various tea procuring units where such measurements and evaluation of quality of tea is carried out on a regular basis find it difficult to maintain desired speed of evaluation involving such extensive manual intervention. Accordingly, it is very difficult to maintain desired standards of evaluation on one hand and demand for faster evaluation on the other hand following such manual method. Moreover, day by day the bulk/varieties to be tasted and evaluated is on the rise and presently the situation is such that on an average there is a need for about 1500 measurement to be done in a single day. Such huge demand of faster evaluation of density of varieties of tea therefore necessarily require increased number of tea tasters / operators. However, more numbers of tasters and operators apart from being cost extensive is also found to be complex since the same would require more persons and space to carry out the operation. Also in view of such involvement of more nos. of tea tasters/persons the desired consistency in evaluation of the various varieties of tea would also necessarily be affected.
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OBJECTS OF THE INVENTION
It is thus the basic objective of the present invention to provide for a system of fast and reliable evaluation of density of solid or liquid substances especially various varieties of tea which would be simple to operate and capable of readily evaluating multiple stocks of tea varieties to thereby meet the present day demands of the tea industry for faster evaluation of tea density and at the same time maintaining desired standards of evaluation.
Another object of the present invention is to provide for an automated system for evaluation of density of various varieties of tea which would take care of the present day needs of the tea industry for large scale measurement/evaluation depending upon the market demands without involvement of extensive manual resources and related complexities.
Yet another object of the present invention is to provide on effective ultrasonic sensor based automated system for fast and accurate measurement of the bulk density of any substance of any liquid or solid form such as tea and the like which would be fast as well as accurate.
Yet further object of the present invention is directed to provide for an automated system for measuring, recording and storing bulk density of solid or liquid substances such as tea and the like which would enable on line generation of density based quality characteristics and attributes of such substance/tea and facilitate the trading of such substances by way of a faster and reliable evaluation technique.
SUMMARY OF THE INVENTION
Thus according to the present invention there is provided a system for fast on¬line measuring of density of solid or liquid substances such as tea and the like comprising:
i. atleast one vibrator means;
ii. means to support pre-weighed samples to be tasted in containers with predefined shapes and internal volumes on said vibrator means;
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iii. at least one ultrasonic sensor means operatively connected to a control unit such that the sensor is adapted to transmit and receive reflected ultrasonic pulses to ascertain fill-level of the samples in the respective containers;
iv. said control means also adapted for ascertaining the density of the sample utilizing the said values of the fill level of the sample in the container.
The above system of the invention is particularly adapted to measure the bulk density of samples of tea of various varieties. For the purpose various varieties of tea pre-weighed are fed into respective containers which are preferably cylindrical containers. The same weighed varieties of tea in the respective cylinders (each of same dimension and internal volume) reach different levels in the respective cylinders. The ultrasonic sensors are adapted to register the height of the tea leaf in each of the cylinders by noting the difference in the height of the tea leaves in the cylinder (standard reference cylinder - sample cylinder). Thereafter, according to the formula density = mass/volume, the density of the various varieties of tea leaves is calculated by the control unit and stored in the computer for future reference.
The containers/cylinders are preferably mounted on a tray which is supported by the vibrating system which is used principally to vibrate the contents in the cylinders especially in case of powders, granular substances such as tea leaves to ensure that the material in the containers are adequately packed in the cylinder and avoid any wrong indications of the height of the material due to any void/unfilled regions upto the level of the contents in the respective cylinders.
In accordance with a preferred aspect the automated system for measuring the density of varieties of tea comprises: i. at least one vibrator means;
ii. at least one tea sample tray comprising plurality of cylindrical containers mounted thereon for containing the pre-weighed variety of
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tea samples in respective containers, all said containers of same dimensions and internal volume ;
iii. at least one ultrasonic sensor means adapted to move in predetermined sequence (X,Y, direction) from one cylinder to the other operatively connected to a control unit such that the sensor is adapted to transmit and receive reflected ultrasonic pulses to ascertain the fill-level of tea in each said container;
iv. said control unit adapted to ascertain the density of the respective tea samples utilizing the values of the fill-level of the tea in each container.
Preferably, each such tray accommodating the tea sample can be adapted for accommodating 100 cylindrical containers for the tea samples. For the purpose, the tray is subdivided into four segments each comprising 25 cylindrical containers into which the tea samples are weighed and put. The trays are mounted effectively with respect to the vibrating table (Z axis) to achieve the desired jogging effect to get the desired flat top meniscus of the fill level of the tea in the respective cylinders.
It is possible that instead of one such tray, plurality of such trays can be arranged vertically and/or horizontally one after the other each operatively connected to the vibrator means. Such arrangement would enable further increasing the capacity of the system to evaluate more nos. of samples in a given time.
The ultrasonic sensor is preferably selected to have a sensing diameter of 18 mm with a 3.5 degrees beam reflected sonic divergence. The sensor is adapted to move in a predetermine sequence (X, Y direction) from one cylinder to the other, and register the height of the tea leaves in each of the cylinders by noting the difference in height of the tea leaves in the cylinder (standard reference cylinder - sample cylinder). Thereafter, according to the standard formula, density = mass/volume, the density of the tea leaves is calculated by the control unit and stored in the computer for future references.
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The sensor moving system is adapted with precision guide screws and driver controls whereby the sensor could be moved to a particular cylinder or to a sequence of cylinders sequentially. The controller can be further adapted to track the exact location of the cylinder and locate a sensor on it.
ihe details of the invention, its objects and advantages are explained hereunder in greater detail in relation non-limiting exemplary illustrations as per accompanying figures wherein-
Figure 1 is a schematic representation of the vibrator means supporting the tray carrying the pre-weighed samples in multiple cylinders used in the system of the invention;
•^gure 2 is a top view illustrating the segmented arrangement of a tray variety accommodating about 100 cylinders for containing the pre-weighed tea samples.
Figures 3A and 3B are sectional illustrations, elevation and side views respectively of the densitometer system in accordance with the present invention.
Figure 1 is a schematic representation of the vibrator means supporting the tray carrying the pre-weighed samples in multiple cylinders used in the system of the invention. As clearly illustrated in said figure, the system of the invention comprises basically of the vibrator means (VM) which is preferably an EM vibrator electrically operated. The vibrator means supports a tray means (TM) which supports plurality of cylindrical containers (CC) of defined height and volume say 1DD mi plastic measuring cylinder.
The vibrating means can preferably be in the form of a vibratory table such as made of suitable material such as mild steel and having a pre determined table size and load of the vibrating table. The vibrating table is operable by electrical means. The vibrating table is adapted to vibrate in the Z-axis so that the contents in the respective container maintained on the tray means are
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also vibrated and jogged to ensure a flat meniscus to facilitate the measuring of the fill-level of the respective containers.
To facilitate movement of the sensor the same is maintained on a sensor mounting system. The ultrasonic sensor of suitable sensing capacity is used. Preferably, an ultrasonic sensor with a sensing diameter of 18 mm with a 3.5 degree beam reflected sonic divergence is used. The sensor is adapted to move in a pre-determined sequence (x, y direction) from one cylinder to the other, and registers the height of the tea leaf in each of the cylinders by noting the difference in the height of the tea leaves in the cylinder (standard reference cylinder - sample cylinder). The sensor moving system is precise (within 0.5 mm) achieved with precision guide screws and driver controls. The sensor could be moved to a particular cylinder also. The controller used is adapted to track the exact location of the cylinder and locate the sensor on it.
Reference is now further invited to accompanying figure 2 which illustrate ■more clearly the arrangement of the various cylinders in a four segmented tray adapted to carry out evaluation of about 99 samples (one cylinder being used as reference cylinder) at a time. As clearly illustrated in said figure, the tray is segmented in four parts with each part accommodating 25 cylindrical containers for the pre-weighed samples to carry out the 99 sample evaluation at a time.
Reference is now invited to figures 3A and 3B wherein the automated system for fast online measuring of density of substances such as tea of the invention naving the movable ultrasonic sensor is illustrated in greater detail. As shown in said figures 3A and 3B, the system of the invention comprises the vibrator (6) on which there is mounted means for supporting plurality of sample holding means. In the figures, such sample holding means is shown to comprise of plurality of test tubes (9) containing variety of tea samples. The ultrasonic sensor (5) is shown to be mounted with respect to guide means including linear guide (1) for Y axis, end limit (2) for sensor, screw means for X axis (7) and Screw means for Y axis (10). To facilitate the X and Y axis
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movement , stepped motor for X axis (3) and a stepped motor (8) for Y axis are also provided . Also provided to facilitate the X and Y axis movement are the screw (7) for X axis and screw (10) for Y axis. A junction box (4) is adapted to include the above provisions for the movable sensor means.
It is possible by way of the illustrated embodiment of the system of the invention to maneuver the sensor with respect to plurality of sample holding units, such as the plurality of test tubes containing samples, For the purpose and to facilitate such maneuvering of the sensor it is adapted for movement both in the X and the Y axis. This provides for the desired movement of the sensor over each of the plurality of sample holding means one after the other and also where the sample holding means are disposed in several tiers over the vibrator means. It is thus possible using such a system to carryout in bulk estimation of variety of samples of tea by way of a very fast and effective system. The operation of the system is now described hereunder:
First the tray containing the cylindrical containers with pre-weighted tea samples are positioned atop the vibrator. Thereafter, the vibrating machine is operated which provides for a vertical to and fro (Z direction) vibratory action of the tray along with the cylinders and its contents. Such a vibrating action provides for adequate settling of the contents of the tea in the respective containers and in particular facilitates achieving the flat meniscus of the top of the contents in the respective cylinders.
Once the height of the contents in the respective cylinders are settled the ultrasonic sensor is maneuvered and located over the respective cylinders and the ultrasonic sensor is operated to generate the ultrasonic wave and receive the reflecting wave from the top of the contents in the respective cylinders. For the purpose, the sensor is moved in a predetermined sequence (X,Y direction) from one cylinder to the other and thereby registers the height of the tea leave in each of the cylinders (standard reference cylinder - sample cylinder). Thereafter, using the formula density = mass/volume, the density of
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the tea is calculated by the control unit and stored in the computer for future reference.
It is thus possible by way of the above disclosed system of the invention to carry out large scale evaluation of bulk density of any substance in solid or liquid form such as tea leaves and the like. The system is found to be advantageous especially for evaluation of density of tea varieties as it is automated such that in about 20 minute it could measure/record and store bulk density values of about 100 samples. Moreover, the system is adapted for further increase in rate of evaluation by adding on further trays and sample containers based on the no. of varieties of tea samples to be evaluated and the time alloted. The system avoids too much manual intervention in density measurement and thereby ensures a more steady and effective evaluation of the bulk density and related characteristics of tea and like products.
While the above exemplary illustrations have been detailed in relation to tea product, the system can be equally used in detergent factories etc. wherein there is regular need to measure bulk density of detergent products and for allied applications.
The system which is automated and avoids manual intervention is supposed to carry out fast and effective measurement of density of various grades of tea saving valuable man hours and making such process of evaluation, fast, cost effective and at the same time extremely reliable.
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WE CLAIM:
1. An improved system for fast on-line measuring of density of solid substances
such as tea comprising :
i. at least one vibrator means;
ii. means to support pre-weighed samples to be tasted in containers with
predefined shapes and internal volumes on said vibrator means; iii. at least one ultrasonic sensor means operatively connected to a control unit
such that the sensor is adapted to transmit and receive reflected ultrasonic
pulses to ascertain fill-level of the samples in the respective containers; iv. said control means also adapted for ascertaining the density of the sample
utilizing the said values of the fill level of the sample in the container.
2. A system for fast on-line measuring of density of varieties of tea claimed in claim 1 wherein the means to support pre-weighed samples to be tested comprises at least one tea sample tray comprising plurality of cylindrical containers mounted thereon for containing the pre-weighed variety of tea samples in respective containers, all said containers of same dimensions and internal volume.
3. A system for fast on-line measuring of density of varieties of tea claimed in claim 1 to 2 wherein the means to support pre-weighed samples to be tested comprises more than one tea sample tray arranged vertically and/or horizontally.
4 A system for fast on-line measuring of density of varieties of tea claimed in
claims 1 to 3 wherein the said tea sample tray are adapted to accommodate 100 cylindrical containers mounted thereon.
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A system for fast on-line measuring of density of varieties of tea claimed in claims 1 to 4 wherein the said tea sample tray is subdivided into four segments each comprising 25 cylinders.
A system for fast on-line measuring of density of varieties of tea claimed in claims 1 to 5 wherein plurality of cylindrical containers counted on the tea sample trays that is supported by a vibrator means.
A system for fast on-line measuring of density of varieties of tea claimed in claims 1 to 6 wherein the said tea sample trays arranged vertically and/or horizontally one after the other are operatively connected to the vibrator means.
A system for fast on-line measuring of density of varieties of tea claimed in claims 1 to 7 wherein the said tea sample tray is mounted effectively with respect to the vibrating table (Z axis) to achieve the jogging effect to get the flat top meniscus of the fill level.
A system for fast on-line measuring of density of varieties of tea claimed in claims 1 to 8 wherein the ultrasonic sensor means adapted to move in predetermined sequence (X,Y; direction) from one cylinder to the other operatively connected to a control unit such that the sensor is adapted to transmit and receive reflected ultrasonic pulses to ascertain the fill-level of tea in each said container.
A system for fast on-line measuring of density of varieties of tea claimed in claims 1 to 9 wherein the ultrasonic sensor has a sensing diameter of 18mm with ' a 3.5 degrees beam reflected sonic divergence.
A method of measuring density of solid substances such as tea using a system as claimed in claims 1 to 10 and said method comprises -
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a. measuring weight of substances for which density is to be measured ;
b. feeding the substances to the containers ;
c. vibrating the containers ;
d. measuring the height of the substance in the containers by means of
ultrasonic sensors ;
e. calculating the density of substance %
12. A system for fast on-line measuring of density of varieties of tea substantially as hereindescribed and illustrated with reference to the accompanying figures.
Dated this 19th day of January 2004
Dr. Sanchita Ganguli
OfS.Majumdar&Co.
Applicant's Agent