STEP MOTOR MECHANISM FOR ELECTRONIC TIMEPIECE

• US 3,855,781 A
• Filed: 12/21/1973
• Issued: 12/24/1974
• Est. Priority Date: 12/22/1972
• Status: Expired due to Term

• Current Assignee: Hiroyuki Chihara, Yoshito Ushiyama
• Original Assignee: Hiroyuki Chihara, Yoshito Ushiyama
• Inventors: Ushiyama, Yoshito, Chihara, Hiroyuki
• Primary Examiner(s): Jackmon, Edith Simmons
• Application Number:
  US05/427,208
• Time in Patent Office: 368 Days
• Field of Search: 58/4A,23R,23D 318/213,445,456
• US Class Current: 368/28
• 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
• CPC Class Codes: G04C 3/143 Means to reduce power consumption by reducing pulse width or amplitude and related problems, e.g. detection of unwanted or missing step

Abstract

A step motor driving mechanism for use in an electronic timepiece and especially suitable for reducing the current consumption thereof is provided. Means are provided for detecting the rotational position of a step motor and controlling the current applied thereto during a loaded and unloaded condition. The detecting means is coupled to the driving and control circuit to reduce the pulse width or peak value of the current applied to the step motor during the unloaded condition thereof to thereby reduce the current necessary to drive same.

Claims

1. An electronic timepiece having a step motor and comprising a quartz crystal vibrator producing a high frequency time standard signal;

divider circuit means for producing low frequency time signals in response to said high frequency time standard signals;

a gear train driven by said step motor and adapted to place the step motor in one of a loaded and unloaded conditions;

load detection means for detecting the condition of the step motor and supplying a signal corresponding thereto; and

driving and control means intermediate the dividing circuit and the step motor for receiving the low frequency signals from the dividing circuit and applying same to the step motor for driving same, the signals applied to the step motor being controlled by application of the load detection signal to the driving and control circuit means.

2. An electronic timepiece as depicted in claim 1, wherein the time signals applied to the step motor are controlled by reducing the pulse width of the drive signals upon detection of an unloaded condition.

3. An electronic timepiece as claimed in claim 2, wherein the load detection means is adapted to detect the angle of rotation of the rotor and apply signals corresponding to the angular position of the rotor to the driving and control means.

4. An electronic timepiece as claimed in claim 3, wherein said step motor includes a rotor and said load detection means includes a detecting coil for detecting the angular rotation of the rotor.

5. An electronic timepiece as claimed in claim 4, wherein said driving and control means includes circuit means for receiving the signal detected by the detection coil and using same to gate the low frequency time signals supplied by the divider to thereby reduce the pulse width thereof when the unloaded condition is detected.

6. An electronic timepiece as claimed in claim 2, wherein the gear train includes a wheel gear, and said load detecing means includes a decoder means for mechanically sensing the condition of the step motor and supplying signals to the control and driving means representative of such condition.

7. An electronic timepiece as claimed in claim 6, wherein the wheel gear is a fourth wheel, and said decoder includes a second jumper sensing the fluctuation in the fourth wheel, and the decoder is made of barium titanate so that when the jumper engages the fourth wheel, the second jumper is vibrated to supply the load detection signal to the driving and control circuit.

8. An electronic timepiece as claimed in claim 1, wherein the drive signals applied to said step motor have a uniform pulse width and are controlled by reducing the peak value thereof during an unloaded condition.

9. An electronic timEpiece as claimed in claim 1, wherein said gear train includes a calendar advancing wheel and said load detection means includes means for sensing the orientation of said date advancing wheel, when said wheel is in a calendar date advancing position.

10. An electronic timepiece as claimed in claim 9, wherein the driving and control means includes an electronic switching element and said orientation sensing means providing a switching signal to the electronic switching element for controlling the peak value of the drive signal applied to the step motor.

11. An electronic timepiece as claimed in claim 10, wherein said orientation sensing means includes a rotating conductive calendar advancing wheel, a sensing element adapted to provide said switching signal when said sensing element is in contact with said calendar advancing wheel, and insulator means disposed on part of said advancing wheel between said sensing element and said conductive wheel, the absence of the insulator on the calendar advancing wheel defining a loaded condition of the step motor.

12. An electronic timepiece having a step motor and comprising a quartz crystal vibrator producing a high frequency time standard signal;

divider circuit means for producing low frequency time signals in response to said high frequency time standard signals;

a gear train driven by said step motor and adapted to place a load on the step motor;

load detection means for detecting the load condition of the step motor and supplying a signal corresponding thereto; and

driving and control means intermediate the dividing circuit and the step motor for receiving the low frequency signals from the dividing circuit and applying same to the step motor for driving same, the signals applied to the step motor being controlled by application of the load condition signal to the driving and control means.