Charging circuit for an analog electronic timepiece
AssigneeSeiko Epson Corporation
InventorsMotomu Hayakawa, Masahito Yoshino
Life of this patent
Estimating the term…
Abstract
A chargeable analog electronic timepiece chargeable by an external A.C. voltage source includes a step motor which includes a driving coil. A motor driving circuit coupled to both terminals of the coil receives the A.C. voltage and selectively applies a charge to the coil for either driving the motor or charging a chargeable battery. A charge control circuit controls a period in which the switching circuit charges the chargeable battery and drives the motor. A PN junction placed in parallel to the switching circuit rectifies the A.C. voltage during charging of the secondary battery so that a single motor coil may drive the watch hands as well as charge the battery and a diode of the switching circuit may be utilized as the rectifier.
Claims13
A chargeable analog electronic timepiece chargeable by an external A.C. voltage source comprising:
- a step motor having a driving coil, the coil having a first terminal and a second terminal;
- a chargeable battery;
- motor driving means coupled to the first terminal of the coil and the second terminal of th coil for receiving A.C. voltage and selectively applying a charge to the coil for driving the motor and for selectively applying a charge to the coil for charging the chargeable battery;
- charge control means for controlling the period in which the motor driving means charges the chargeable battery and drives the motor;
- and
- rectifying means for rectifying the A.C. voltage prior to charging of the secondary battery, the rectifying means including at least one PN junction placed in parallel to the motor driving means.
A chargeable analog electronic timepiece chargeable by an external A.C. voltage source comprising:
- a step motor having a driving coil, the coil having a first terminal and a second terminal;
- a chargeable secondary battery having a positive terminal and a negative terminal;
- a first switching means and a second switching means, the first switching means being coupled intermediate the first terminal of the coil to the positive terminal of the secondary battery and a second switching means being coupled intermediate the second terminal of the coil and the positive terminal of the secondary battery, third switching means and fourth switching means, the third switching means being coupled intermediate the first terminal of the coil and the negative terminal of the battery, the fourth switching means being coupled intermediate the second terminal of the coil and to the negative terminal of the battery, each switching means being in either an OFF state or an ON state;
- and
- rectifying means for rectifying the A.C. voltage during charging of the secondary battery, the rectifying means including a respective PN junction disposed in parallel to each switching means, and the step motor producing driving pulses and the switching means short circuiting terminals of the coil after determination of each output of the driving pulse and thereafter at least three of the respective switching means being in the OFF state.
A chargeable analog electronic timepiece chargeable by an external A.C. voltage source comprising:
- a step motor having a driving coil, the coil having a first terminal and a second terminal;
- a chargeable secondary battery;
- a first switching means and a second switching means, the first switching means being coupled intermediate a first terminal of the coil and the positive terminal of the secondary battery and a second switching means being coupled intermediate the second terminal of the coil and the positive terminal of the secondary battery, third switching means and fourth switching means, the third switching means being coupled intermediate the first terminal of the coil and to the negative terminal of the battery, the fourth switching means being coupled intermediate the second terminal of the coil and the negative terminal of the battery, each switching means being in either an OFF state or an ON state;
- and
- rectifying means for rectifying the A.C. voltage during charging of the secondary battery, the rectifying means including a respective PN junction disposed in parallel to each switching means, each switching means including a MOS type FET having a substrate and a drain for driving the motor and the PN junction including a parasitic diode formed between the substrate and drain of the MOS type FET and the step motor producing driving pulses and the switching means short circuiting terminals of the coil after determination of each output of the driving pulse and thereafter at least three of the respective switching means being in the OFF state.
Dependencies are inferred from the claim text.