| United States Patent | 3,810,355 |
| Ito | May 14, 1974 |
ELECTRONIC CIRCUIT FOR QUARTZ CRYSTAL WATCH
Abstract
A watch movement constructed as an electronic circuit provided with an oscillating circuit having a quartz oscillator or resonator and a capacitor roughly adjusting the frequency of the oscillator with a variable capacitor for finally adjusting the frequency of a time base output thereof. The oscillating circuit is temperature compensated. The oscillator output is received by a fourteen-stage frequency-dividing circuit having complementary MOSFETS arranged as binary circuits with a wave-shaping circuit reducing the frequency of the oscillations to about one Hz. The frequency-divided signal is applied to driving circuitry that develops in conjunction with pulse-generating circuitry opposite-going pulses applied to a transducer that converts the pulses to rotary motion using a driving gear wheel of a second hand of a watch and of a gear train thereof.
| Inventors: | Ito; Kazuo (Tokyo, JA) |
| Assignee: |
Kabushiki Kaisha Daini Seikosha
(Tokyo,
JA)
|
| Appl. No.: | 05/235,640 |
| Filed: | March 17, 1972 |
| Mar 20, 1971 [JA] | 46-15669 | |||
| Current U.S. Class: | 368/189 ; 331/116R; 368/156; 368/202; 968/446; 968/490; 968/548; 968/823; 968/902 |
| Current International Class: | G04C 13/00 (20060101); G04C 3/00 (20060101); G04G 3/00 (20060101); G04C 3/14 (20060101); G04F 5/06 (20060101); G04G 3/02 (20060101); G04F 5/00 (20060101); G04C 13/10 (20060101); G04c 003/00 (); G04b 027/00 () |
| Field of Search: | 58/23R,23A,23AC,23TF,23V,23D,85.5 310/25,36 318/127,133 |
| 3540207 | November 1970 | Keeler |
| 3576099 | April 1971 | Walton |
| 3608301 | September 1971 | Loewengart |
| 3664118 | May 1972 | Walton |
| 3665697 | May 1972 | Dome |
| 3597634 | August 1971 | Flaig |
| 3616638 | November 1970 | Bennet et al. |
| 3212252 | October 1965 | Nakai |
Assistant Examiner: Jackmon; Edith Simmons
Attorney, Agent or Firm:
What I claim and desire to secure by Letters Patent is:
1. A watch movement for a watch comprising, an oscillating circuit developing an output having a selected frequency and representative of a time base signal, frequency-dividing means receptive of the time base signal for dividing its frequency and for developing an output signal having a substantially lesser frequency, means receptive of said output signal for developing driving pulses, transducer means receptive of the driving pulses and having means developing as an output mechanical driving force; and switch means for manually selectively inhibiting said frequency-dividing means from developing said output signal at will and for manually selectively enabling said frequency-dividing means to develop said output signal at will to manually selectively stop the watch movement and to manually selectively restart the watch movement instantaneously at a desired time; whereby the watch movement may be manually stopped and restarted instantaneously at a desired time to accurately correspond to an external time reference wherein said frequency-dividing means has inhibit means responsive to a first signal having a first voltage value applied thereto enabling said frequency dividing means to develop said output signal and responsive to a second signal having a second voltage value applied thereto for inhibiting said frequency-dividing means from developing said output signal, and wherein said switch means has means connected to said inhibit means for selectively applying thereto in response to said first signal and said second signal.
2. A watch movement according to claim 1, in which said frequency-dividing means comprises a circuit having means to reduce said time base signal to a frequency of about one Hz.
3. A watch movement according to claim 1, in which said transducer means comprises a second gear driven rotationally in one direction by said driving force.
4. A watch movement according to claim 3, in which transducer means developing a mechanical force comprises a coil receptive of said pulses, a pawl oscillatable under control of said pulses driving said gear.
5. A watch movement according to claim 4, including a second hand driven accurately from said second gear, and means connecting said second hand and gear.
6. A watch movement according to claim 1, in which said oscillating circuit comprises a quartz resonator.
7. A watch movement according to claim 6, in which said frequency-dividing means comprises a circuit having a plurality of frequency-dividing stages, each stage comprising complementary MOS transistors.
8. A watch movement according to claim 7, in which said stages comprise 14 stages, and a wave-shaping circuit dividing the frequency of the time base signal.
9. A watch movement according to claim 1, wherein said first voltage comprises a positive voltage and said second voltage comprises a negative voltage.
BACKGROUND OF THE INVENTION
The present invention relates generally to electronic watches and more particularly to an electronic circuit for quartz crystal watches.
Electronically driven watches having a quartz crystal resonator providing the time base are known and the electronic circuitry thereof makes use of conventional bi-poled transistors. The conventional bi-poled transistors are used even though MOSFETS are commercially available because it was not possible to drive MOS transistors with a low voltage supply, such as a battery used in watches.
Complicated electronic circuits used in watches are generally integrated circuits and MOS transistors are advantageously miniaturized in these electronic circuits. An advantage of MOS transistors is that in a complementary configuration when one of the P or N-type MOS transistors is in an "on" state, the other transistor having a common drain therewith, is in an "off" state and has a high resistance or impedance. Therefore, complementary configurations of MOS transistors consume very little power.
SUMMARY OF THE INVENTION
It is a principal object of the present invention to provide a highly reliable electronic circuit for driving a watch and accurately controlling its time-keeping by accurately controlling the driving of the second hand of a watch.
Another object is to provide electronic circuitry that can be constructed as integrated circuits thereby reducing the size of the driving circuitry.
According to the invention, an electronic circuit for a watch comprises an oscillator or oscillating circuit developing an output having a selected frequency and representative of a time base signal. The oscillating circuit has a quartz oscillator or resonator and its frequency is roughly adjusted by a capacitor and is settable to a fine frequency adjustment by a variable capacitor. The oscillating circuit is compensated for ambient temperature by a capacitor. The time base signal is received in a frequency-dividing arrangement constituting a plurality of frequency-dividing circuits connected in cascade. These frequency-dividing circuits constitute fourteen stages of MOS transistors arranged in complementary binary circuits. The frequency of the output of the final stage is one Hz and is received in a wave-shaping circuit which constitutes a one stage binary circuit of MOS transistors in a complementary arrangement. A reset switch is provided connected to the frequency-dividing circuitry and responsive to a manual force applied thereto to inhibit the output of the frequency-dividing circuits for accurately setting the watch and including the setting of the second hand of a watch with a reference time standard.
The divided frequency signal is applied as pulses to a driving circuit and a pulse-generating circuit which generate oppositely travelling pulses which are applied to a coil of a transducer that converts these pulse signals to rotary motion for accurately driving the second hand of a watch and a gear of a rgear train thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagram of an electronic circuit of a watch according to the invention;
FIG. 2 is a circuit diagram of a frequency-dividing circuit arrangement of the circuit in FIG. 1; and
FIG. 3 is a fragmentary perspective view of a transducer driven by the circuit in FIG. 1.
Other objects and advantages will appear from the following description of an example of the invention, and the novel features will be particularly pointed out in the appended claims.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The electronic circuit according to the invention illustrated in FIG. 1 comprises an oscillator 1 developing a predetermined frequency signal corresponding to a time base signal applied to a frequency-dividing circuit 2 reducing the frequency of the oscillator output. A reset switch 3 is connected to the frequency-dividing circuit to allow setting of the watch with reference to a time standard. The time base signal with reduced frequency is applied to a driving circuit 4 and a pulse-generating circuit 5 which, as well as the other circuits, is connected to a power source or battery 6. Oppositely applied pulses are delivered by the pulse-generating circuit and driving circuit and applied to a transducer, shown in FIG. 3, converting the pulse signals to rotary motion as hereinafter described.
The oscillating circuit 1 has a quartz oscillator or resonator 1a to which is connected a fixed capacitor C.sub.11 for compensating for temperature variations of the oscillator and a second fixed capacitor C.sub.13 which establishes a rough adjustment of the frequency of the oscillator. A fine adjustment is set with a variable capacitor C.sub.12 likewise connected to the resonator as illustrated. A transistor T.sub.11 is connected in series with a resistor in a voltage dividing arrangement across the power source 6 for driving the quartz resonator.
The frequency-dividing circuit 2 is constructed as an integrated circuit illustrated in FIG. 2. In the detailed circuit illustrated in FIG. 2, an input terminal .phi. corresponds to an input terminal 2a of the block in FIG. 1 and another terminal 2b connected to the positive terminal of the battery is represented by a corresponding terminal V.sub.dd illustrated in FIG. 2. A terminal 2c is connected to the negative voltage terminal of the battery. An output terminal 2d corresponds to the output terminal labeled "Out" and a terminal 2e corresponds to a reset circuit terminal R. All of the points in FIG. 2 having the reference R are connected to the terminal R although the equivalent connections are not shown in the block diagram in FIG. 1. The points of the circuit in FIG. 2 having a reference V.sub.dd are connected to the positive terminal of the power source.
The oscillating frequency signal output of the oscillator appears at the input terminal .phi. and has a frequency of 16384 Hz produced by the quartz resonator. The input terminal .phi. is connected to two diodes one of which is connected to the power source as illustrated and the other grounded and through complementary MOS transistors in an inverter configuration into a frequency-dividing stage DIV Al where the output appears at Q.sub.1, Q.sub.1. In this first state the frequency is divided and the output has a value of 8192 Hz which is one half of the input frequency and the signal at Q.sub.1 is inverted.
As can be seen, the frequency-dividing circuit arrangement constitutes fourteen stages of binary circuits connected in cascade and denoted DIV A1 - DIV A9, DIV B1 - DIV B5. The circuits labeled DIV A have complementary MOS transistors of the configuration of the circuit DIV A1 and those labeled DIV B have the circuit configuration of DIV B2. The inputs are labeled Q.sub.in and Q.sub.in and the outputs are labeled Q.sub.1 Q.sub.1 to Q.sub.14 Q.sub.14. The bars over the reference letters indicate the signal inversions taking place within the frequency-divider.
The time base signal applied to the frequency-dividing circuitry is reduced in frequency in the fourteen stages. The frequency is 4096 Hz at the output of the second stage DIV A2 and is one HZ at the output of the fourteenth stage DIV B5. The signal having a frequency of one HZ is applied to a wave-shaping circuit WS constituting complementary MOS transistors in a binary circuit arrangement. The output signal of the 14 stages in the frequency-dividing circuit has a frequency of one Hz and has a pulse width or duration of approximately 500 msec. This is applied to the waveshaping circuit WS which reduces the pulse width to eight msec., and the output signal of the frequency-divider has this eight msec. pulse width at the output terminal "Out." The wave-shaping circuit WS is connected through MOS transistors to a junction between the eighth and ninth dividing circuits DIV A8 - DIV A9 and to the twelfth stage DIV B3 as illustrated.
The reset circuit 3 constitutes a switch having two movable contacts 3a, 3b operable under the control of the crown stem or winding stem, not shown, of the watch in which the circuit is employed. One movable contact 3a makes connection with a fixed contact 3c connected to the positive terminal of the power source as illustrated and in series with a second fixed contact 3d likewise connected to the positive terminal and with which the other movable contact 3b makes electrical contact in the position illustrated which corresponds to a condition in which the crown stem is in an "In" position. The two movable contacts act as a back-up for each other so that in the event that there is trouble at one switch contact the other establishes the circuit since both movable contacts are connected in series to a common terminal 2e of the frequency-dividing circuit.
A third fixed contact 3f is connected to the negative terminal of the power source as illustrated and the second movable contact 3b makes contact with it when the crown stem is pulled to an "Out" position for purposes of setting the hands of the watch, not shown. In the "Out" condition of the crown stem the hands, including the second hand, are stopped but the circuit continues energized. Thus it can be seen that a positive potential is applied to the reset terminal 2e when the watch is in operation and a negative potential is applied to this reset terminal 2e when the movable contact 3b is actuated by the crown stem in its "Out" position to make contact with the fixed contact 3f. The circuit thus is constantly energized.
The driving circuit 4 has an input transistor T.sub.41 with its base connected to the output terminal 2d of the integrated circuit 2 through a resistor and has its collector connected through a resistor to the base of a transistor T.sub.42 which has its collector connected to a collector of a third transistor T.sub.43 having its emitter connected to the emitter of the input transistor T.sub.41. The collector of the input transistor is connected to the collector of a fourth transistor T.sub.44 having an emitter connected to the emitter of the second transistor T.sub.42 and a base connection through a resistor to the collector of the third transistor which has its base connected to the emitter of a fifth or output transistor T.sub.45 having a collector connected as illustrated through a junction connection between the collectors of the input and fourth transistors as illustrated. The connection between the emitters of the second and fourth transistors is connected to the positive terminal of the battery and the connection between the emitters of the input and third transistors is connected to the negative terminal.
A coil L is connected between the collectors of the input and third transistor as shown and is part of a transducer described below.
The fifth or output transistor T.sub.45 of the driving circuit 4 is connected to an input transistor T.sub.51 of the pulse-generating circuit 5 by having its base connected to the collector thereof. The pulse-generating circuit 5 has a monostable multivibirator configuration having a second transistor T.sub.52 and the time constant of which is controlled by a resistor R.sub.51 and a capacitor C.sub.51. The multivibrator transistor T.sub.52 is connected to a diode D connected to a junction connected with the output terminal of the integrated circuit.
The pulse output of the integrated circuit 2 having an eight msec. pulse width is applied to the base of the input transistor T.sub.41 from the output terminal 2d rendering the input transistor T.sub.41 and the second transistor T.sub.42 conductive so that they are in an "On" state. Consequently a current flows in the driving coil L in the direction indicated by an arrow labeled a.
The pulse generating circuit 5 is triggered by a reverse pulse generated at the output terminal 2d due to the direction of the diode D. Thus the transistor T.sub.52 turns "off" during the period determined by the time constant of the circuit while the input transistor T.sub.51 is in an "on" condition. Consequently a current flows in the driving coil L in an opposite direction shown by the arrow b since the transistors T.sub.45, T.sub.43 and T.sub.44 of the driving circuit are then in an "on" condition.
Provision is made for converting the two pulse outputs of the driving and pulse-generating circuit applied to the driving coil L to convert these pulse signals to rotary motion for accurately driving the second hand of the watch, not shown. This is accomplished by a transducer illustrated in FIG. 3 in which a magnetic bar 7 has the coil L wound thereon and has a rotatably mounted pallet 8 rotated by the attractive force between the magnetic poles of the magnetic material 7 and a permanent magnet 9 on the axis of the pallet. The pallet is constructed to oscillate and engage peripheral teeth of a second gear wheel 10 mounted on an axis 11 on which is coaxially disposed a second gear wheel 12 and a second hand 13.
When the pulse current flows in the coil in one direction, the pallet 8 is attracted by the attractive force between a magnetic pole of the magnetic material and the permanent magnet 9 and when the pulse current flows in an opposite direction, the magnetic pole of the magnetic material is oppositely magnetized. Accordingly, the pallet is urged to rotate in an opposite direction so that it oscillates and carries out its oscillation within a period of one second. Each time the pallet engages the peripheral teeth of the second wheel 10, the wheel is rotated in a same direction half a pitch. The second hand 13 is kept stable during the absence of a pulse in the coil, by a stop spring 14 which cooperates with peripheral teeth on the other wheel 12. These teeth are twice in number as the number of peripheral teeth on the second wheel so that the second hand is held stabilized for each half pitch movement of the second gear wheel.
Those skilled in the art will recognize that the circuit according to the invention provides a compact watch movement constructed as a miniaturized circuit and more particularly miniaturized complementary MOS binary circuits in integrated form. This configuration increases the life of the battery since the circuit consumes only a very little electrical power. Moreover, the time can be accurately set because the second hand, which is stopped when the crown stem is retracted, can be set in accordance with a reference time standard by pushing in the winding stem and the movement starts substantially immediately after the winding stem is pushed in so that the watch can be accurately set, even with respect to the seconds, with reference to a time standard.
The electrical circuitry and contacts of the conventional watches are eliminated and high reliability is established with the electronic circuit according to the invention. A threshold voltage less than 0.8V can be realized for both P and N channelled MOS transistors by using film gates in their construction.
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