WO2000019281A1

WO2000019281A1 - Apparatus and method for positioning the clockwork of a watch movement equipped with a calendar mechanism

Info

Publication number: WO2000019281A1
Application number: PCT/CH1999/000436
Authority: WO
Inventors: Christian Giulieri; Lucien Falco; Michel Vermot
Original assignee: Precimeca S.A.
Priority date: 1998-09-24
Filing date: 1999-09-14
Publication date: 2000-04-06

Abstract

The invention concerns an apparatus and a method for positioning the clockwork of a watch movement equipped with a calendar mechanism. The apparatus comprises essentially: a support (1) for receiving the movement (2); a device driving (20) in rotation the arbor (21) for setting the movement; a light source (14) generating a coherent light beam directed on the calendar mechanism date disc (13); a photoelectric detector (16) arranged for receiving the light beam reflected by the disc (13) and producing an electric signal as a function of its intensity; and an electronic device (18) analysing said electric signal arranged for generating a control pulse stopping the driving device (20) when the clockwork reaches the position corresponding to midnight.

Description

APPARATUS AND METHOD FOR POSITIONING THE GEAR OF A WATCH MOVEMENT PROVIDED WITH A CALENDAR MECHANISM

The present invention relates to an apparatus and method for positioning the train of a watch movement provided with a calendar mechanism.

With this type of movement, it is necessary, when it is nested, to place the hands so that they indicate midnight when the calendar mechanism performs its jump (instant mechanism) or finishes its movement (drag mechanism), otherwise the date information will not be correct.

Such an operation is still frequently carried out manually, the watchmaker rotating the time-setting rod of the watch until he sees the date indicator jump. He can then correctly place the hands, with the certainty that they indicate midnight.

When the watchmaker performs this operation on a movement equipped with an instant calendar mechanism, he does not know when the date indicator will jump. If it turns the cog slowly, it may take a long time. If, on the contrary, it rotates at high speed, precision suffers.

When the operation has been carried out, it is, of course, necessary to control it. The watchmaker then rotates the hands over 24 hours to ensure that the jump is made at the right time. If this is not the case, he must correct the position of the hands, which risks deforming them and represents a waste of time.

To facilitate the location of the position corresponding to midnight, it is known to use acoustic detectors. This is possible with calendar mechanisms which include a jumper ensuring the positioning of the indicator. The detector is activated by the noise generated by the jumper when it finishes moving the indicator.

Certain modern watch movements, requiring a minimum drive torque, include mechanisms without jumper, which consequently generate no noise. Acoustic detection is therefore not usable.

Furthermore, mastering the sound environment is difficult. There is, in fact, a non-negligible risk that unwanted noise will generate a control signal at an inappropriate time. The main object of the present invention is to propose an apparatus making it possible to precisely position the train of a watch movement provided with a calendar mechanism, so as to be able to drive out the hands in the adequate position. This device is characterized in that it comprises:

- a support intended to receive the movement, - a device for driving in rotation the movement setting time rod,

- a light source generating a coherent light beam directed on one of the parts of the calendar mechanism,

a photoelectric detector arranged so as to receive the beam returned by this part and producing an electrical signal as a function of its intensity, and

- an electronic device for analyzing this signal arranged to deliver a control pulse stopping the drive device when the gear train has reached the position corresponding to midnight.

Advantageously, the part of the calendar mechanism on which the light beam is directed is the date disc appearing behind a window made in the watch dial. In a particularly advantageous embodiment, the electronic device of the device according to the invention comprises:

means for generating an initialization pulse as soon as there is a variation in the detector signal corresponding to the setting in motion of the date disc, and

- delay means responding to the initialization pulse by delivering the command pulse to stop the drive device at the end of a predefined time after the pulse has been generated. The delay thus caused between the setting in motion of the date disc and the stopping of the device for driving the time-setting rod is substantially constant for a given caliber and corresponds to the duration of training of the calendar mechanism. . This time is a few seconds for an instantaneous mechanism, but it can be more than an hour for a dragging mechanism.

Detecting the position of the gear train by optical means considerably reduces sensitivity to the environment. However, the light beam returned to the detector can vary greatly in intensity, depending on the surface condition of the date disc. To guarantee perfect operation, whatever the working conditions, the electronic device therefore also comprises means for adjusting the intensity of the light beam emitted by the source and means for adjusting the amplitude of the output signal. of the photoelectric detector.

So that the device according to the invention can be used with different watch calibers, it is desirable that the position of the device for rotating the time-setting rod be adjustable, so as to be able to align on it before entering it. This is why, in a particularly advantageous embodiment, the drive device comprises: a crew mounted to pivot on a base around a first axis substantially parallel to that of the time-setting rod, and

- A motor system mounted to pivot on this equipment around a second axis parallel to the first and comprising a motor and a clamp actuated by the motor and intended to grip the end of the time-setting rod.

Advantageously, the apparatus according to the invention comprises means for adjusting the position of the beam coming from the light source and comprising: - a cylindrical frame mounted in rotation on a base around its axis coincident with the axis of movement watch, and

- a cylindrical socket with an axis parallel to that of the frame, inside which the source is fixed eccentrically.

The present invention also relates to a method for positioning the train of a watch movement provided with a calendar mechanism. It is characterized in that it consists of:

- mount the movement on a support,

- projecting a beam of coherent light onto a part of the calendar mechanism whose surface has a roughness substantially greater than half the wavelength of the beam light,

- transform the beam of light returned by the part into an electrical signal,

- train the train, - analyze the signal to determine the position of the train corresponding to the calendar date change, and

- interrupt the drive train when this position is reached. Advantageously, the part on which the beam is projected is the date movement of the watch movement.

The time required to allow the passage from one date to the next being practically constant for a given caliber, it is advantageous to detect the start of the training of the calendar mechanism and to rotate the gear train for a predefined time, equivalent to time required to allow the mechanism to move from one date to the next.

Other advantages and characteristics of the invention will emerge from the description which follows, given with reference to the appended drawing, in which: - Figure 1 illustrates the general principle of the apparatus according to the invention;

- Figures 2a to 2c show, according to different views, the movement drive devices; and

- Figure 3 shows the structure of the device for its parts relating to the optics and positioning of the movement. The measuring device according to the invention exploits a physical phenomenon which, in English, is called "speckling". It occurs when a coherent light beam is projected onto a piece with a frosted surface, such as the date disc of the calendar mechanism of a watch movement. We then observe that the light scattered by this surface is distributed in a way that seems random, with the formation of light and dark spots. If a photoelectric detector is placed in the field of scattered light and the part is moved, the detected light intensity varies in a large proportion, generally by a factor of 2 to 3, but which can sometimes reach 10 If, on the contrary, the room is stationary, the light intensity remains constant. It is thus possible to detect the movement of the part.

As can be seen in FIG. 1, the device according to the invention comprises a support 10 intended to receive a watch movement 12 whose dial 12a is pierced with a window revealing a date disc 13. A coherent light generator 14 is arranged above the movement 12 so as to direct its beam on the window to touch the visible part of the date disc 13. A photodetector 16 receives the light beam returned by the disc and produces an electrical signal which is applied to the input of an analysis and control electronics 18. FIG. 1 also shows a device 20 for driving in rotation the time-setting rod 21 of the movement. The support 10, the generator 14, the photodetector 16 and the drive device 20 will be described more precisely with reference to FIGS. 2 and 3. The coherent light generator 14 is advantageously a laser diode, for example that sold by the Siemens house under the reference Cohérent VLM 3. The photodetector 16 is a photoelectric cell such as that sold by the same house under the reference BPX61.

The electronics 18 comprises a circuit 22 comprising a power supply 22a connected to the light generator 14 to supply it with the energy necessary for its operation and an analysis circuit 22b generating an initialization pulse as soon as a variation of the signal of the detector 16 corresponding to the setting in motion of the date disc. The circuit 22b essentially consists of a filter eliminating the DC component of the signal, followed by a rectifier and a shaping circuit.

Adjustment devices 24 and 26 are respectively connected to the power supply 22a and to the analysis circuit 22b to vary the intensity of the light emitted by the source 14 and the amplitude of the output signal of the detector 16. These two devices are made using variable amplifiers. The electronics 18 further comprises a timer 28 connected to the output of the analysis circuit 22b and a supply circuit 30 of the drive device 20 connected to the output of the timer 28. A switch 32 is used to activate the supply circuit 30 which also responds to the initialization pulse of circuit 22b, delayed by timer 28, by the delivery of a command stop device pulse drive 20 at the end of a predefined time after the initialization pulse has been generated.

The various components of the electronics 18 are well known to those skilled in the art and will therefore not be described in more detail. The general principle of operation of the device according to the invention is as follows.

We start by fixing the watch movement 12 on the support 10. The drive device 20 is then connected to the movement setting stem 21. By actuating the switch 32, the drive device 20 is started, which begins to rotate the rod 21 and therefore the gear train.

As long as the date disc 13 is stationary, the signal from detector 14 is constant, but it varies as soon as the cog begins to drive the disc. When the circuit 22b has detected a variation of this signal, it controls the engagement of the timer 28. After a determined delay time, the duration of which has been adjusted according to the controlled movement, the supply circuit 30 receives from the timer l order to stop the drive device 20. The gear train is thus in a position corresponding to midnight. Such an operation requires a time of between 1 and 10 seconds, depending on the initial position of the gear train. It then suffices to drive out the needles by means of an ad hoc tool, which is not part of the invention. Advantageously, this installation can be carried out by a device sold under the name of "Seven Hands" by the house Brimatechnic in Cornaux (Switzerland).

FIG. 2 shows, in more detail, the device 20 for driving the movement. It shows, in a, a profile view of the device, in b a section along line b-b in FIG. 2a and in ç a section, along line c-c in FIG. 2b.

As can be seen more particularly in Figures 2a and 2b, the drive device 20 comprises a base 40, on which are mounted two pillars 42 each provided with a pivot 42a and which carry a crew 43, of substantially rectangular shape. The latter comprises a cylindrical shaft 44 having an axis 45 engaged in the pivots 42a, two arms 46 fixed by one of their ends to the shaft 44 and extending radially with respect to the axis 45, and a cylindrical bar 48 fixed to the other end of the arms 46. A motor system 49, which will be described in more detail with reference to FIG. 2c, is frictionally mounted on the bar 48. A threaded rod 50, provided with a head 50a , is engaged in a hole 46a in one of the arms 46 and in a tapped hole 40a in the base 40. Two springs 52 and 53 are respectively interposed between the base 40 and the arm 46, on the one hand, the arm 46 and the head 50a, on the other hand. In this way, the arms 46 descend or rise when the head 50a is screwed or unscrewed.

FIG. 2c shows the motor system 49. It comprises a frame 54, mounted pivotally and sliding on the bar 48. The frame 54 carries a motor 56 provided with a shaft 58 connected to a clamp 60 intended to clamp the end (crown ) of the time-setting rod 21 of the movement 12. The clamp 60 is formed of a substantially cylindrical part provided with slots which define four fingers 60a extending longitudinally in the direction opposite to the motor 56 and whose free end is substantially conical in shape. The part opposite the fingers 60a forms a back 60b connected to the shaft 58. A tube 64, open at its two ends, surrounds the clamp 60 as well as a part of the shaft 58. It comprises, at one of its ends, a bearing surface 64a surrounding the shaft 58 and, at the other end, a flap 64b, of conical shape intended to cooperate with the fingers 60a. A coil spring 66 is interposed between the back 60b and the seat 64a. It acts axially, so that the fingers 60a and the flap 64b cooperate to generate a radial force which tends to bring the fingers closer to one another and thus close the clamp 60 on the crown of the time-setting rod 21 of the movement 12. The tube 64 is produced in two parts 64c and 64d, screwed together, to allow the spring 66 and the clamp 60 to be put in place.

A lever 68, pivotally mounted on the frame 54, has two arms 68a and 68b perpendicular to each other. The arm 68a extends substantially axially outside the frame 54. The arm 68b comprises two lugs 68c, only one of which is visible in the drawing, which surround the shaft 58 in the vicinity of the external face of the part 64a of the tube . When a force is applied to the arm 68a of the lever 68, the lugs 68c push the tube 64 outwards, thus freeing the fingers 60a which open to allow the withdrawal or the positioning of the crown of the rod time setting. By releasing the lever 68, the spring 66 pushes the tube 64 back, closing the clamp 60.

The structure, as described, can be used with all movements fitted with a time-setting rod on the side. It suffices to use an adequate support and to align the clamp 60 on the axis of the time-setting rod 21, by means of the threaded rod 50, then to move the motor system so that the clamp comes grip the crown of the time setting rod.

Figure 3 shows, in more detail, the measuring device as well as the movement support. We find the support 10 of the movement 12, mounted on the base 40, the coherent light generator 14 as well as the photodetector 16. A bracket 70 is mounted on the base 40 and has a cylindrical hole 70a in which a frame 72 can rotate. The latter carries a positioning finger 74 of the movement, mounted slidingly, which comes to bear on the dial around its center, and a bushing 76, pivotally mounted in a hole 72a of the frame. The socket 76 carries the generator 14, the photodetector 16 as well as a semi-transparent mirror 78 and an optic 80. The generator 14 emits a light beam oriented along an axis 82 perpendicular to the plane of the movement 12 and offset with respect to the axis of the socket 76. This beam passes through the semi-transparent mirror 78, then the optics 80 which focuses it on the date disc where it is broadcast. Part of the scattered light is reflected on the mirror 78 and reflected on the photodetector 16, which generates an electrical signal, processed by the analysis and control electronics to manage the system.

The device makes it possible to adjust the position of the sleeve 76 so that the axis 82 cuts the disc 13 in the space defined by the window of the dial 12a. The adjustment is made by rotating the frame 72 in the bracket 70 and the sleeve 76 in the frame. In order to prevent the system from going wrong, the bush 76 is fixed to the frame 72 by means of a clamping screw 84. The same solution, not shown in the drawing, can be used to block the frame on the bracket 70. The apparatus described above can include many variants, without departing from the scope of the invention. Thus, the relative positioning of the motor system 49 and the time-setting rod, on the one hand, of the light beam and the calendar window, on the other hand, could be done by means of micrometric screws. It is also possible to integrate this device into a production chain. In this case, the clamp 60 would, of course, be controlled by an automated system.

Claims

1. Apparatus for positioning the train of a watch movement provided with a calendar mechanism, characterized in that it comprises: - a support (10) intended to receive said movement (12),

- a device (20) for rotating the rod (21) for setting the time of the movement,

- a light source (14) generating a beam of coherent light directed on one of the parts (13) of said mechanism, - a photoelectric detector (16) arranged so as to receive the beam returned by said part and producing an electrical signal depending on its intensity, and

- an electronic device (18) for analyzing said electrical signal arranged to deliver a control pulse stopping the drive device (20) when the train has reached the position corresponding to midnight.

2. Apparatus according to claim 1, characterized in that the electronic device (18) comprises:

means (22b) for generating an initialization pulse as soon as there is a variation in the signal from the detector (16) corresponding to the setting in motion of the part (13) of the calendar mechanism, and

- timer means (28) responding to the initialization pulse by delivering the command pulse to stop the drive device at the end of a predefined time after the pulse has been generated.

3. Apparatus according to one of claims 1 and 2, characterized in that the electronic device (18) further comprises means (24) for adjusting the intensity of the beam emitted by the light source (14).

4. Apparatus according to one of the preceding claims, characterized in that the electronic device (18) further comprises means (26) for adjusting the amplitude of the detector output signal (16).

5. Apparatus according to one of the preceding claims, characterized in that the drive device (20) is adjustable in position, so as to allow its alignment on the time setting rod (21) before entering it .

6. Apparatus according to claim 5, characterized in that the drive device (20) comprises:

a unit (43) pivotally mounted on a base (40) around a first axis (45) substantially parallel to that of the time-setting rod (21), and

- A motor system (49) pivotally mounted on this equipment around a second axis parallel to the first and comprising a motor (56) and a clamp (60) actuated by the motor and intended to grip the end of the setting rod on time.

7. Apparatus according to one of the preceding claims, characterized in that it comprises means (72, 76) for adjusting the position of the beam from the light source.

8. Apparatus according to claim 7, characterized in that the means for adjusting the position of the beam include:

a cylindrical frame (72) mounted in rotation on a base (70) around its axis which coincides with the axis of the watch movement, and

- A cylindrical sleeve (76) with an axis parallel to that of the frame (72), inside which the source (14) is fixed eccentrically.

9. Method for positioning the train of a watch movement provided with a calendar mechanism, by means of an apparatus according to one of the preceding claims, characterized in that it consists of: - mount the movement on a support,

- directing a beam of coherent light onto a part of the calendar mechanism, the surface of which has a roughness substantially greater than half the wavelength of the light of the beam,

- transform the beam of light returned by said part into an electrical signal,

- train the movement,

- analyze said signal to determine the position of the gear train corresponding to the calendar date change, and

- interrupt the drive train when said position is reached.

10. Method according to claim 9, characterized in that it consists, moreover, in detecting the start of the drive of the calendar mechanism, and in driving said train for a predefined time, equivalent to the time necessary to allow said mechanism move from one date to the next.

11. Method according to one of claims 9 and 10, characterized in that the part of the calendar mechanism on which the light beam is projected is the date disc.