US 3745760 A
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United States Patent 1 Keeler July 17, 1973 ELECTRONIC SWITCH FOR TIMEPIECES Eugene R. Keeler, Suffern, N.Y.
Timex Corporation, Waterbury, Conn.
Filed: Jan. 10, 1972 Appl. No.: 216,684
References Cited UNITED STATES PATENTS 4/1969 l-leermans 318/127 Primary ExaminerRichard B. Wilkinson Assistant ExaminerEdith C. S. Jackmon Attorney-Richard A. Joel  ABSTRACT An electronic switch to provide a long storage life for the battery used in timepieces such as quartz watches is disclosed. The switch includes a transistor connected between the oscillator divider and power supply and a delay circuit coupled across the output from the oscillator-divider andcontrolling the aforesaid transistor. When the balance wheel is held off normal, the delay circuit opens the series switch transistor after a predetermined time interval to minimize battery drain. In a second embodiment, a shunt mode of operation is provided wherein theoutput driver transistor is controlled by a second transistor from the delay circuit. A third transistor in the oscillator input is similarly controlled by the delay circuit. When the balance wheel is held off normal, the delay circuit turns on the second and third transistors thereby minimizing battery drain.
12 Claims, 2 Drawing Figures L M m OSCILLATOR/ DIVIDER DELAY CIRCUIT PAIENIEI] JUL 7 I975 RESET DELAY CIRCUIT \BJ N m w YP MR 2M ?2 MM N x0 0 FIG] DELAY CIRCUIT FIG. 2
ELECTRONIC SWITCH FOR TIMEPIECES BACKGROUND OF THE INVENTION The present invention relates to battery operated timepieces such as quartz watches and particularly to a means for preventing the battery from running down during storage.
In battery-powered timepieces, a means must be provided to prolong the shell life of the battery so that the consumer purchases a watch with relatively long-lived power supply. Conventionally, a switch or guard is provided to disconnect the power supply during storage. A typical arrangement is shown in U.S. Pat. 3,200,578 to R. Besson wherein a switch short circuits a transistor thereby stopping the regulating member of an electric timepiece. Another arrangement is disclosed in Meitinger US. Pat. No. 3,526,088.
In a highly accurate quartz watch, however, means must be provided to disconnect the battery without adversely affecting the timekeeping properties of the watch. Mechanical switches, on the one hand, are often affected by shock and vibration although a copending commonly assigned application filed simultaneously herewith, Ser. No. 216,690 discloses an improved mechanical switch. The present invention, however, relates to an electronic switching arrangement which is particularly suited for use in quartz watches. One such watch is disclosed in US. Pat. No. 3,699,762 to Norman Charles Zatsky, filed Apr. 5, 1971 on a Synchronized Contact Watch which is assigned to the assignee of record of the present invention.
SUMMARY OF THE INVENTION As distinguished from the prior art discussed above, the present invention relates to an electronic switch for watches wherein the power supply or battery is prevented from running down during storage. In a typical watch, particularly of the quartz variety, the switch would include a delay circuit which senses the motion of the mechanical oscillator and opens a series switch transistor between the battery and the oscillatordivider circuit after a predetermined time interval. The delay circuit is reset to zero by each output drive pulse which occurs twice per balance wheel cycle. If the balance wheel is held off normal, however, for a period which exceeds a worst case synchronization interval, the delay circuit completes its predetermined timing cycle and opens the switch transistor turning ofi' the oscillator-divider.
Accordingly, it is an object of this invention to provide a new and improved switch means for battery operated timepieces to prevent drain of the battery during storage.
Another object of this invention is to provide a new and improved electronic switch to disconnect the battery of a quartz watch to prolong the life thereof.
A further object of this invention is to provide a new and improved switch arrangement which senses the motion of a mechanical oscillator, such as a balance wheel, and disconnects the battery when no motion is sensed for a predetermined time interval.
BRIEF DESCRIPTION OF THE DRAWINGS Other objects and advantages of the present invention may be more clearly seen when viewed in conjunction with the accompanying drawings wherein:
FIG. 1 is a circuit diagram illustrating a first embodiment of the invention including a series switch transistor; and,
FIG. 2 is a circuit diagram illustrating a second embodiment of the invention comprising a shunt switch mode of operation.
DETAILED DESCRIPTION OF THE INVENTION Referring to FIG. 1 of the drawings, the invention comprises an electronic switch for a watch, particularly of the type disclosed in US. Pat. No. 3,699,762 mentioned above. The watch includes an oscillatobdivider circuit 10 which counts down pulses from a high frequency quartz oscillator and supplies output pulses to the gate 12 of an output driver transistor 1 l. The pulses are used to synchronize a balance wheel motor 50 by feeding pulses to drive coil 17 during the contact closed interval of contact 16. The contact 16 is connected in series with the source 14 and drain l3 circuit of transistor 11 and is intermittently closed by the oscillating balance wh'eel (not shown).
According to the present invention, a delay circuit is connected between the source 13 of the output driver transistor 11 and the gate 20 of a series switch transistor 19. The source 21 and drain 22 circuit of the transistor 19 is in series with the power supply to the oscillator-divider circuit 10.
The present invention functions to eliminate drain on the battery during storage by sensing the motion of the balance wheel and disconnecting the battery from the oscillator-divider circuit 10 under predetermined conditions. When the balance wheel is held off normal in a conventional manner by pulling out the watch crown, the contact 16 is held open. The delay circuit 18 is normally reset to zero each time a positive pulse appears at the drain 13 of transistor 11 but, in this instance, the delay circuit 18 completes its timing cycle of approximately five seconds and opens transistor 19. The battery is, therefore, effectively removed from the circuit.
If, due to angular accelerations of the watch, the contact closure interval is temporarily phase displaced with respect to the counted down quartz frequency to a point where transistor 11 is saturated during the entire contact closure interval, the delay circuit will start its timing function. In other words the delay circuit 18, which normally senses balance wheel motion and is reset when a positive voltage appears at the drain I3 twice per balance wheel cycle, cannot sense motion if transistor 11 is already on. When the balance wheel resynchronizes to the drive frequency, the positive voltage appears and the delay circuit 18 is reset. A time interval of approximately five seconds is selected for the delay circuit 18 since this is generally longer than that needed for the watch to resynchronize in the worst case.
If, on the other hand, the delay circuit 18 completes its timing cycle, the series switch transistor 19 opens and turns off the oscillator-divider circuit 10. This would occur only as a matter of intent, for example, when it is desired to store the watch. The balance wheel would then be held ofi' normal in a conventional manner initiating the timing cycle. When the balance wheel is released the contact 16 closes, resetting the delay circuit, and closing the switch transistor 19 which in turn starts the oscillator.
FIG. 2 depicts a second embodiment of the invention comprising a shunt switch mode of operation. The oscillator 29 including a quartz crystal 28, and divider 30, are part of a watch similar to that described above, as well as output driver transistor 31, contact 36 and coil 37. A pair of transistors 45 and 39 are provided in the output of the delay circuit 38. The transistor 45 is connected with its source 48 and drain 47 across transistor 31 and its gate 46 coupled to the delay circuit 38. The transistor 39 is connected across the input of the oscillator 29 with its gate 40 connected to the delay circuit 38.
The circuit functions similar to the embodiment of FIG. 1 and hence will not be described in detail. Transistor 45 is provided to turn off transistor 31 when the delay circuit 38 completes a timing cycle. Transistor 39 is similarly turned on by the delay circuit at the end of a timing cycle halting the oscillator 29. The power supply is thus removed from the circuit to prevent battery drain and with the oscillator stopped the battery drain approaches zero because of the low static power requirements of the CMOS counter stages.
It is now obvious that when the oscillator stops the driver transistor 31 could be in its conducting state. As noted previously transistor 45 precludes this possibility. If the driver transistor 31 were saturated during the storage period the start up pulse generated by the freed balance wheel would not be sensed when the crown is pushed in to start the watch.
It is to be understood that the above-described arrangements are merely illustrative examples of the application. Numerous other arrangements may be readily devise by those skilled in the art which will embody the principles of the invention and fall within the spirit and scope thereof.
1. In a battery-operated timepiece having an oscillator-divider circuit providing pulses to a driver to synchronize an electromechanical motor, the combination comprising:
a delay circuit connected to the driver output and the oscillatondivider battery input, and
switch means in the oscillator-divider battery input controlled by the delay circuit to open the battery connection when the electromechanical oscillator is stopped for a predetermined time interval.
2. A timepiece according to claim 1 wherein:
the delay circuit comprises a circuit which is reset by pulses from the driver to the electromechanical motor but, if no pulses are received for a predetermined time interval, the circuit opens the switch means to prevent batterydrain.
3. A timepiece according to claim 1 wherein:
the switch means comprises a transistor connected in series between the battery and the oscillatordivider circuit and having its input connected to the delay circuit.
4. A timepiece according to claim 1 wherein:
the electromechanical motor includes a balance wheel oscillator.
5. In a battery operated timepiece having a high frequency oscillator circuit and a multiplicity of frequency divider stages providing pulses to an output driver stage to synchronize an electromechanical oscillator in series therewith, the combination comprising:
first transistor means in the input to the oscillator a delay circuit connected to the first transistor means to prevent oscillations of the high frequency oscillator when the electromechanical oscillator is stopped for a predetermined time interval by cutting off the first transistor means and, second transistor means in the output of the driver to prevent the driver from being in the conducting 5 state at the same time, said second transistor means being connected to the output of the delay circuit and operated thereby.
6. A timepiece according to claim 5 wherein:
the delay circuit comprises a circuit which is intermittently reset by drive pulses to the electromechanical oscillator but if the pulses are stopped for a predetermined interval, said circuit completes its timing cycle to stop the high frequency oscillator by opening the second driver transistor in the oscillator input.
7. A timepiece according to claim 5 wherein:
the oscillator and divider circuits, include semiconductor components of the CMOS type so that the current drain from the battery is limited to the quiescent requirements of the CMOS circuitry when the electromechanical oscillator is stopped.
8. In a battery-powered quartz watch having an oscillator-divider circuit and an output driver transistor to provide synchronizing pulses through an intermittent contact to a balance wheel, the combination comprisa series switch transistor having its source-drain circuit between the battery and the oscillator-divider circuit, and
a delay circuit connected between the output driver transistor and the gate of the series switch transistor to sense the motion of the balance wheel and disconnect the battery if the balance wheel is stopped for a predetermined time interval in order counted indicating that the electro-mechanical oscillator has been stopped with the contact open, said counting means being normally reset by each pulse through the intermittently closed contact.
10. The method of minimizing battery drain in a timepiece having a high frequency oscillator and series connected divider and a driver circuit to provide synchronizing pulses through a contact'to an electromechanical oscillator comprising the steps of:
providing a first switching means in the high frequency oscillator input from the battery to control the oscillator, providing a second switching means in the input to the driver to open the driver under predetermined conditions, and
counting the divider output pulses and closing the first and second switching means if a predetermined number of pulses are counted indicating that the mechanical oscillator has been stopped, said counting means being normally reset by each pulse through the intermittently closed contact.
11. In a battery operated timepiece having a high frequency oscillator circuit and a multiplicity of frequency 12. A timepiece according to claim ll wherein:
the delay circuit comprises a circuit which is reset by the drive pulses to the electromechanical oscillator but, if the pulses are stopped for a predetermined time the circuit opens the battery connection to prevent battery drain.
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