Complete specification

Electrical Testing Method and System

Field of Invention:

The field of this instant invention relates to building a high efficient testing system and method for testing quartz watches to filter all sort of defects and to achieve higher profit through customer satisfaction & loyalty.

Back-Ground of Invention:

There are two versions of Gear box called as ' 1M & 2M Gear Boxes' which contains 12 & 22 small precise components including four coils of thickness just 18 Micron . Even though the assembled Gear boxes are inspected manually, the rejection % was high around 40% at the supplier end due to its complex mechanism & tiny nature which was very difficult to filter with manual inspection.

The Gear Box comes in two variant which contains many precise delicate components .Out of all the components, the stepper motor is the critical part

The background of this invention lies in the field of developing a new Testing mechanism which test the Gear boxes by making all the wheels to complete one revolution through electrical pulses and determine any defects.
Pior-Art:

DI - US4192131A teaches a step motor driving and control mechanism for use in an electronic timepiece for reducing the current consumption thereof is provided. Load detection circuitry detects the load condition of the step motor by detecting the signáis induced in the drive coil of thé step motor after each stepping of the rotor. The load detection circuitry selectively produces a load condition signal in response to detecting current peaks representative of a predetermined load condition of the step motor. The load detection circuitry is characterized by the use of MOS transistors therein for accurately detecting the occurrence of the current peaks.

Driving and control circuitry is provided for receiving a low frequency timekeeping signal produced by a divider circuit and a load detection signal, when same is selectively produced by the load detection circuitry. In response to the presence or absence of a load detection signal applied thereto, the drive and control circuitry is adapted to vary the duration of the pulse width of a drive signal applied to the step motor to effect a driving of same

Here the main difference between this instant invention and US 419213 is that a stepper motor control mechanism for electronic timepiece has used for detecting load, which is induced in drive coil after each stepping of rotor.

D2 - EP0859294A1 teaches a a control device and a control method for a wristwatch or the like in which a stepping motor for hand movement and an electricity generating device are used together. The effects of magnetic fields from the electricity-generating device can be mitigated, thereby providing a timing device, which operates hand movement without error and at high precisión. In particular, a detecting pulse (SP1) is output to both the driving pole side and the reverse pole side. Thus detection time is extended so that even in the event that a magnetic field with polarity is output as noise from the electricity generating device, the detection sensitivity is improved to a point where the magnetic field can be detected.; Then, rotation detecting of the driving rotor is omitted by means of outputting an auxiliary pulse (P2) with great effective electric power instead of the normal driving pulse (Pl) in the event that a magnetic field is detected. This prevents mistaken detection which could lead to error in the movement of the hands.

Here the main difference between this instant invention and EP0859294A1 is that an auxiliary pulse is supply to stepper motor for detecting driving rotor, rotate or not roíate and for detecting an external magnetic field.

D3 - US4430007A comprises measuring, upon application of a drive pulse to the actuating coil 5 of the stepping motor, the variation in the magnetic induction flux in the stator of the motor, and interrupting the drive pulse when the variation in flux reaches a predetermined valué. Measurement of the variation in flux may be effected, for example, by detecting the current in the actuating coil and integrating the difference between the supply voltage of the actuating coil and the product of the current by the d.c. resistance of the coil, or by providing an auxiliary detection coil 71 and integrating the voltage induced therein in an integrator 73, 74. When the integrator outputs exceeds the magnitude of either a positive or negative reference voltage, a comparator circuit 78, 79, 81 provides the signal to a circuit 13 to terminate the drive pulse.

Here the main difference between this instant invention and US4430007A is that a method is used for reducing the power consumption of the stepping motor of an electronic timepiece by supplying a voltage drive pulses to the motor.

Documents DI - D3 deal with supply of frequency pulses to the stepper motor and the circuit being used to measure or detect the current consumption of rotor of stepper motor. However, these documents reveal the use of stepper motor and pulses being used to measure the load on the driving coil in DI, to detect rotor rotation in D2 and to reduce the power consumption of the stepping motor in D3. None of them specifically disclose the use of the giving pulse signáis to stepper motor for testing gear train.

When compared with the closest prior art DI, the invention is novel. Also, since none of the documents individually or together teach a person to use electronic supply board for supplying the high frequency pulses to stepper motor to find the defects in watch gear train, it can be concluded that the invention has an inventive step.

Summary:

The present invention is a comprehensive testing mechanism of watch gear train to test or check the freeness & smóothness of the wheels, coil's resistance, wheel's teeth damage and any small friction. The available mechanism for gear train testing was not able to monitor the entire defect properly (e.g. all teeth damage). Henee, a new mechanism, which supplied high frequency pulses to stepper motor by electronic circuit until all the wheels completed one revolution in mínimum time has been developed. Electronic circuit or program based switching mechanism is used to measure the current.consumption of rotor, which in turn helps to determine the defects. Henee, according to the inventor watch gear quality and production rate has been improved.

Moreover this instant invention teaches a method of electrical testing in a time display device comprising the steps of
(a) Supplying high frequency pulses to a stepper motor by a electronic circuit
(b) Monitoring and measuring consumption whenever a pulse is supplied by an Electronic circuit / switching mechanism
(c) Détermining errors and flaws in the watch wheels / gear wheels.
(d) Filtering the defects / flaws

The foregoing abstract is not to be taken as limiting the invention described herein, and in order to understand the full nature and extent of the technical disclosure herein, reference should be made to the accompanying drawings and detailed description

Brief description of drawings:

Fig 1 shows a flow chart of showing the embodiment of the instant method Detailed Description:
The 1M Gear Box consist of 12components.The stepper motor has two coils (one for rotating the Rotor in a Clockwise direction & other for rotating the rotor in Counter-Clockwise direction). The 2M Gear Box consist of 22 components. There are 2 Stepper motor with coils each for rotating in both clockwise & counter clockwise direction. In both the cases, The motor drives a wheel which drives the other and it continúes till the last wheel on which the hands are fixed. To check the freeness of the wheels, coil's resistance and to also defect any wheel's teeth damage, small friction, burr etc, a method has to be developed, which determines all the defects.

For this, a simple Pulse Generator which provides rotating power to the Rotor and tries to monitor the rotation of the wheel through láser sensor was developed. But all defects like Wheel's teeth damage, rotor jam, was not monitored and a really new method and concept was needed at this stage

Then the concept of providing Pulse through a readily available Electronic Circuit Board (which can supply alternative Pulses at a fixed Pulse Width and frequency) was exercised. The ECB is powered from Movement Analyzer equipment "Witschi AQ2". The equipment supplies a voltage of 2.6V and mbnitors the current consumption consumed by the Motor for its rotation. The current consumption is in the range of Micro-Amps. A lot of triáis were done and finally a method which supplies pulses to the Stepper motor was derived upon, till the Final wheel makes 1 complete revolution (i.e 180 revolution of the rotor). This will make all the wheels to make at least one complete revolution. But making all the wheels to complete 1 revolution will result in high cycle time which leads to lower production rate unwarranted for.

So now, a new and novel method / concept which supplies pulses at a higher frequency, say 60 Hz and makes 180 revolution of the rotor in a fraction of secs. has now been developed.

This new mechanism vide figure 1, supplies high frequency pulses to a stepper motor by electronic circuit until all the wheels. completed one revolution in mínimum time has been developed. Electronic circuit or program based switching mechanism is used to measure the current consumption of rotor, which in turn helps to determine the defects.

The equipment is programmed in a way to monitor the consumption whenever a pulse is supplied by the ECB. This helped us to determine even a small friction/Jam in any teeth of rotor or wheels and also helped us to filter the defects before exporting the same . For testing watches, this method monitors the current consumption for only 2 or 3 revolutions of the rotor. By this method , we can make the all the wheels to make one complete revolution resulting in better filtration which will evéntuaüy leads to a Zero market returns

This innovation has never been used in any other watch manufacturer and its uniqueness lies in the fact that it can determine any small deficiency in the movements including wheel teeth damage, burr etc. by making all the wheels to complete at least 1 revolution

First time 60Hz Pulse signal to the Watch stepper motor has been used which no other watch manufacturer has ever tried .This has enabled to go for faster consumption measurement and to filter all defects in fraction of time To make a complete revolution of all the wheels, the equipment has to provide so many pulses (1Hz pulses) which will consume lot of time resulting in a higher cycle time leading to lower prodüctivity .

So this new method has been developed to provide pulses at a higher frequency (60 Hz Pulses) which will make all the wheels to complete one revolution in a fraction of secs resulting in higher prodüctivity
To measure the current consumption for both the direction is not possible with the Existing equipment .But this new program and a switching mechanism have been developed, which measures the current consumption for both direction in a sequential manner programmed

Uses / Advantages and Industrial Applications:

The Out-going quality has been improved and the rejection rate has been reduced from 40 % to less than 0.1% resulting in an higher yield rate and higher customer satisfaction. He shifted the production load from china to India after we implemented this project. This project also led to revenue generation.

While considerable emphasis has been placed herein on the specifíc structure of the preferred embodiment, it will be appreciated that many alterations can be made and that many modifications can be made in the preferred embodiment without departing from the principies of the invention.

These and other changes in the preferred embodiment as well as other embodiments of the invention will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the forgoing descriptive matter is interpreted merely as illustrative of the invention and not as a limitation.

CLAIMS We Claim

1. A method of electrical testing in a time display device comprising the steps of
(a)Supplying high frequency pulses to a stepper motor by a electronic circuit
(b)Monitoring and measuring consumption whenever a pulse is supplied by an Electronic circuit / switching mechanism
(c) Determining errors and flaws in the watch wheels / gear wheels.
(d) Filtering the defects / flaws

2. The method as claimed in claim 1 , step (a) wherein the high frequency pulses are applied till 180 revolutions of the rotor ismade in mínimum time

3. The method as claimed in claims 1 and 2 wherein the mínimum time is a fraction of seconds

4. The method as claimed in claims 1 and 2 wherein the high frequency is 60 Hz.

5. The method as claimed in claim 1 , step (b) wherein measurement of current consumption determine the defects of the watch wheel / gear wheel

6. The method as claimed in claim 1, steps (c) and (d) and claim 5 wherein the defects identified can be wheel's teeth damage, small friction, burr, rotor jam etc.

7. The method as claimed in the preceding claims wherein the current consumption is done only for only 2 or 3 revolutions of the rotor

8. The method as claimed in claim 1 , step(a) and claim 2 wherein all the wheels complete one revolution in a fraction of second thereby resulting in better filtration and rectification of errors

9. The method as claimed in the preceding claims wherein employing 60Hz pulse signáis enables faster consumption management,

10. A time display device enabled to perform the method steps as claimed in claims 1-9.

11. The time display device of claim 10 wherein the device is a quartz watch

12. A method of electrical testing in a time display device substantially as herein described with respect to the accompanying drawings.