Citizen Watch Company, Ltd.

Citizen Holdings Company, Ltd.

Ryoji Iwakura

Shigeru Morokawa

Takakazu Yano

Takaaki Nozaki

Masami Fukuda

Tatsuo Nitta

Katsuyoshi Aihara

Shinichi Komine

Kazutoshi Takahashi

Fukuo Sekiya

Kiyotaka Igarashi

Kazuo Sakamoto

Yukio Otaka

An electric watch is characterized by including a transmitting circuitfor generating a plurality of transmitted signals, transmitting electrodesandfor outputting the output signals generated by the transmitting circuit, a signal modulating membercomposed of a rotor arranged adjacently to the transmitting electrodesandin a non-contact manner for modulating the transmitted signals, a receiving electrodearranged adjacently to the signal modulating memberin a non-contact manner for receiving the transmitted signals modulated by the signal modulating member, a receiving circuitfor amplifying received signals received by the receiving electrode, and a detecting circuitfor detecting mechanical position information of the signal modulating memberbased on the received signal amplified by the receiving circuit

Electric timepiece

A time keeping device of an electric timepiece comprising one motor that can rotate in the forward direction and the reverse direction, a branch mechanism, and a plurality of wheel trains that are branched by the branch mechanism, wherein the motor is rotated in the forward direction to drive one wheel train thereby to carry out a mechanical display, and is rotated in the reverse direction to drive the other wheel train thereby to carry out another mechanical display. The time keeping device further comprises a merge mechanism in addition to the branch mechanism, and a plurality of wheel trains that are branched by the branch mechanism and are merged by the merge mechanism. The motor is rotated in the forward direction to drive one wheel train thereby to carry out a mechanical display, and is rotated in the reverse direction to drive the other wheel train thereby to carry out another mechanical display.

Timer of electric timepiece

Charging a storage cell requires the electromotive force exerted at a photogenerating cell in addition to the voltage equal to or higher than the forward on voltage developed at an backflow preventing diode. Therefore, the charging is inefficient. Moreover, the area of the backflow preventing diode must be large in consideration for a current supply from the photogenerating cell at a high intensity of illumination. A charging circuit, constructed using a differential amplifier, which has a power supply therefor separated from another power supply, is used as a direction-of-current detecting circuit that detects the direction of current from a voltage difference between two different power supplies. Consequently, a switch is logically turned on or off depending on whether charging or non-charging is under way. Thus, on voltage to be developed during charging is lowered. Moreover, the size or area of a transistor that acts as a logical circuit is made smaller than that of the backflow preventing diode. Furthermore, the energy of a storage cell included in the charging circuit is hardly consumed in any states.

Charging circuit

A crystal oscillator circuit using CMOSFETs including an oscillator circuit that is constructed of a resonating section and an amplifying section having a CMOSFET, a reference current source circuit for generating a reference current which determines a bias current of the amplifying section, and a control signal generator circuit for controlling the reference current source circuit to make a bias current larger than that in the oscillation status when the oscillator circuit is in the non-oscillation status. As a result, the reference current source circuit constant-current biases the DC bias of the amplifying section without depending on the source voltage. Therefore, it can lower the driving source voltage of the oscillator circuit. Further, only the bias current of the amplifying section is increased during the oscillation starting period of the oscillator circuit, so that the oscillator circuit can provide a stable oscillation with low power, without variations in the source voltage.

Crystal oscillator circuit using CMOSFETs

In an electronic timepiece having a primary frequency divider circuit coupled to receive a standard frequency signal and comprising a group of P-channel FETs and a group of N-channel FETs, a bias circuit supplies a bias input to the P-channel FET group and a separate bias input to the N-channel FET group. By providing these bias inputs through current mirror coupling from a standard current source, the response of the primary frequency divider circuit to low amplitudes of the standard frequency signal can be made substantially independent of timepiece battery voltage variations, over a wide range of battery voltages.

Electronic timepiece having improved primary frequency divider response

An electronic timepiece in which an operating state of a timepiece circuit is controlled by a control circuit composed of a counter responsive to clock pulses from the timepiece circuit, a digital/analog converter for converting a digital output signal from the counter to an analog output signal, a potentiometer adapted to generate an analog input signal, and a comparator for comparing the analog output signal and the analog input signal to generate an output signal which is applied to the counter to control the same by which a control signal is generated to control the operating state of the timepiece.

Electronic timepiece with gain/loss adjustment

A quartz crystal oscillator for a timepiece including a complementary field effect transistor (FET) pair, wherein one field effect transistor is constant current-biased and the other field effect transistor is self-biased, with high impedance negative feed back loop circuit. The gates of the field effect transistor pair are AC coupled by a condenser, and the drains of the field effect transistor pair are connected to cooperate for AC amplification. The constant current-biased field effect transistor assures a low constant mean current and low start voltage for the oscillator, and the self-biased field effect transistor assures a sure amplifying operation. The AC coupling of the gates assures a high amplification factor and high efficency in excitation of a quartz crystal resonator of an oscillator, whereby the constitution of this invention is simple and easy to form in a monolithic IC chip for a timepiece.

FET Quartz oscillators

An electronic timepiece equipped with a differentiation carry inhibit circuit arranged to allow a carry operation due to a carry signal produced by a time counter in response to a time unit signal when the timepiece remains in a time correction mode and inhibit a carry operation due to a carry signal arising from a correction signal produced by actuation of a correction switch.

Growing community of inventors

Sayama, Japan

Ryoji Iwakura