Electronic timepiece

• US 4,223,522 A
• Filed: 11/13/1978
• Issued: 09/23/1980
• Est. Priority Date: 02/06/1976
• Status: Expired due to Term

• Current Assignee: Citizen Watch Co Limited (Citizen Electronics Company Limited)
• Original Assignee: Citizen Watch Co Limited (Citizen Electronics Company Limited)
• Inventors: Yamada, Kenji, Nomura, Yasushi, Nakajima, Fumio, Machida, Takayasu
• Primary Examiner(s): Miska, Vit W.
• Application Number:
  US05/960,516
• Time in Patent Office: 680 Days
• Field of Search: 58/23 R, 58/23 BA, 58/23 A, 58/23 D, 58/28 R, 58/28 D, 58/34, 58/85.5, 58/152 H, 340/636, 340/660-663
• US Class Current: 368/66
• CPC Class Codes: G04C 10/04 with means for indicating the condition of the power supply in general G01R31/36
• CPC Class Codes: G04C 3/14 incorporating a stepping motor G04C3/02 - G04C3/12 take precedence generating timing pulses G04F5/00, G04G3/00; setting G04G5/00; synchronisation G04G7/00; generating commutating pulses in masterclocks G04C13/0463, G04C13/02; slave clocks actuated intermittently by electromechanical step advancing mechanisms G04C13/10; control circuits for stepping motors in general H02P8/00

Abstract

An electronic timepiece having a reversible stepping motor to actuate time-indicating hands to provide a time display, which comprises a driver circuit to produce driving current pulses composed of compound pulses appearing each time unit. A rotor of the stepping motor rotates a plurality of steps during each time unit to cause one of the time-indicating hands to advance through unequal intervals to provide a modulated display.

Claims

1. An electronic timepiece, powered by a battery, comprising:

a frequency standard providing a relatively high frequency signal;

a frequency divider providing relatively low frequency signals in response to said relatively high frequency signal;

a waveform converter including first circuit means responsive to said relatively low frequency signals for providing a first pulse train comprising a first series of single pulses consisting of a single pulse produced at the start of each of a series of first unit time intervals, said first pulse train being generated by said first circuit means during normal operation of the timepiece, and second circuit means for providing a second pulse train comprising successive groups of pulses, each of said groups of pulses comprising a predetermined plural number of pulses, the duration of each of said groups of pulses being less than that of each of said first unit time intervals, one of said groups of pulses being produced at the start of each of a series of second time intervals, each of said second unit time intervals having a duration equal to that of said first unit time interval multiplied by a factor which is equal to said predetermined plural number plus one, said second pulse train further comprising a second series of single pulses consisting of a single pulse produced at a predetermined time following the completion of one of said groups of pulses and prior to the commencement of an immediately succeeding group of pulses;

a driver circuit responsive to said first pulse train for providing normal drive pulses and responsive to said second pulse train for providing modulated drive pulses;

means for selectively rendering said first circuit means operative while said second circuit means is held inoperative and rendering said first circuit means inoperative while said second circuit means is held operative, in accordance with whether the timepiece is in a normal and an abnormal operating condition respectively;

a stepping motor responsive to said normal drive pulses for rotating a rotor thereof through a unit angular displacement at the start of each of said first unit time intervals and responsive to said modulated drive pulses for successively rotating said rotor through said unit angular displacement by a number of times equal to said predetermined plural number at the start of each of said second time unit intervals, and for further rotating said rotor once through said unit angular displacement during each of said second unit time intervals; and

display means including at least one hand which is driven by said rotor to be advanced by a single step, which corresponds to one of said first unit time intervals, in response to each rotation of said rotor through said unit angular displacement, whereby said hand is advanced by one step for each of sid first unit time intervals when the timepiece is in said normal operating condition and whereby said hand is advanced by a number of steps equal to said predetermined plural number at the start of each of said second unit time intervala and is further advanced by a single step during each of said second unit time intervals, when the timepiece is in said abnormal operating condition, whereby an indication is givent of said abnormal operating condition.

2. An electronic timepiece according to claim 1, in which said means for selectively rendering said first and second circuit means operative and inoperative comprise sensing means for sensing a normal and abnormal operating condition of the timepiece, to produce an output signal when said abnormal condition is sensed, and changeover circuit means responsive to said output signal for rendering said first circuit means inoperative and said second circuit means operative.

3. An electronic timepiece according to claim 1, in which each of said first unit time intervals has a duration of one second.

4. An electronic timepiece according to claim 3, in which said predetermined plural number has a value of three, whereby said second unit time intervals has a duration of four seconds.

5. An electronic timepiece according to claim 4, in which each pulse of said second series of single pulses is produced after a period of three seconds following the commencement of one of said groups of pulses of the second pulse train.

6. An electronic timepiece according to claim 2, in which said sensing means comprises a battery voltage detector for detecting a drop in voltage of said battery below a predetermined level and for generating said output signal when such a drop is detected.

7. An electronic timepiece according to claim 1, in which said frequency divider produces signals having frequencies of 64 Hz, 32 Hz, 16 Hz, 8 Hz, 4 Hz, 2 Hz, 1 Hz, 1/2 Hz and 1/4 Hz, and wherein said first circuit means comprises a flip-flop which is triggered to a first state in response to said 64 Hz signal and which is triggered to a second state in response to said 1 Hz signal, and a gate circuit having an output of said flip-flop coupled to one input thereof and said 1 Hz signal coupled to another input thereof, for thereby producing said firt pulse train as a series of single pulses φ

₈ having a period of one second and very short pulse width, and wherein said second circuit means comprises a gate circuit coupled to receive said 1/4 Hz signal, said 1/2 Hz signal, said 1 Hz signal, the inverse of said 2 Hz signal and the inverse of said 4 Hz signal at inputs thereof, for thereby producing a signal φ

₁ having a period of 4 Hz, a gate circuit coupled to receive said 4 Hz signal, said 2 Hz signal, the inverse of said 1 Hz signal, and the inverse of said 1/2 Hz signal, at inputs thereof, for thereby producing a signal φ

₂ having a period of 2 seconds, a data-type flip-flop circuit having a data terminal coupled to receive the inverse of said 1/4 Hz signal and a clock terminal coupled to receive said φ

₂ signal, a gate circuit coupled to receive an inverted output from said data-type flip flop and the inverse of said 1/4 Hz signal at input terminals thereof, for thereby producing a signal φ

₄ having a period of 2 seconds, a gate circuit coupled to receive said signals φ

₄ and φ

₁ for thereby producing a signal φ

₅ consisting of a train of relatively long pulses with a period of 4 seconds and with a relatively short pulse occuring at an intermediate point between each pair of said relatively long pulses, a gate circuit coupled to receive said 64 Hz signal, and the inverses of said 32 Hz signal, said 16 Hz signal, said 8 Hz signal at inputs thereof, for thereby producing a signal φ

₆ comprising a train of pulses of very short pulse width and with a period of 1/8 seconds, and a gate circuit coupled to receive said signals φ

₅ and φ

₆ at inputs thereof, for thereby producing a signal φ

₇ comprising successive groups of three pulses of very short pulse width with a period of 4 seconds between each of said groups of three pulses and with a period of 1/8 seconds between successive pulses in a group, and with a single pulse of very short pulse width occuring at a point in time 3 seconds after the initial pulse of each of said groups of three pulses.

8. An electronic timepiece, comprising:

a frequency standard providing a relatively high frequency signal;

a frequency divider providing a plurality of relatively low frequency signals in response to said relatively high frequency signal;

a waveform converter including first circuit means responsive to said relatively low frequency signals for providing a first pulse train comprising a first series of single pulses consisting of a single pulse produced at the start of each of a series of first unit time intervals, said first pulse train being generated by said first circuit means during normal operation of the timepiece, and second circuit means for providing a second pulse train comprising successive groups of pulses, each of said groups of pulses comprising a predetermined plural number of pulses, the duration of each of said groups of pulses being less than that of each of said first unit time intervals, one of said groups of pulses being produced at the start of each of a series of second time intervals, each of said second time intervals having a duration equal to that of said first unit time interval multiplied by a factor which is equal to said predetermined plural number plus one, said second pulse train further comprising a second series of single pulses consiting of a single pulse produced at a predetermined time following the completion of each one of said groups of pulses and prior to the commencement of the immediately succeeding group of pulses;

state sensor means for sensing an operating state of the electronic timepiece, and for producing a first output signal when a normal operating state is sensed and producing a second output signal when an abnormal operating state is sensed;

a changeover circuit comprising gate circuit means coupled to receive said first pulse train and said second pulse train from said waveform converter, being responsive to said first output signal from said state sensor means for passing said first pulse train to an output terminal thereof and inhibiting passage of said second pulse train, and further responsive to said second output signal from the state sensor means for passing said second pulse train to an output terminal thereof, and for inhibiting passage of said first pulse train;

a driver circuit coupled to receive said first pulse train from said changeover circuit means and responsive thereto for producing a train of normal driving pulses corresponding in timing to said first pulse train, and further coupled to receive said second pulse train from said changeover circuit and responsive thereto for producing a train of modulated driving pulses corresponding in timing to said second pulse train;

a stepping motor responsive to said normal drive pulses for rotating a rotor thereof through a unit angular displacement at the start of each of said first unit time intervals and responsive to said modulated drive pulses for successively rotating said rotor through said unit angular displacement by a number of times equal to said predetermined plural number at the start of each of said second time unit intervals, and for further rotating said rotor once through said unit angular displacement during each of said second unit time intervals; and

display means including at least one hand which is driven by said rotor to be advanced by a single step which indicates the passage of one of said unit time intervals, in response to each rotation of said rotor through said unit angular displacement, whereby said hand is advanced by one step for each of said first unit time intervals when said electronic timepiece is in said normal operating state and whereby said hand is advanced by a number of steps equal to said predetermined plural number at the start of each of said second unit time intervals and is further advanced by a single step during each of said second unit time intervals, when the electronic timepiece is in said abnormal operating state, whereby an indication of said abnormal operating state is given.