Electronic watch control device for manual actuation
AssigneeCentre Electronique Horloger S.A.
InventorsJean Fellrath, Jean-Felix Perotto
Life of this patent
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Abstract
An electronic watch control device for manual actuation is disclosed. It comprises a capacitive sensor including a conductive layer on the inner surface of the watch-glass, which is actuated by placing a finger-tip on the outer side of the watch-glass. The sensor is part of a capacitive voltage divider to which a high frequency voltage is applied. Synchroneous detection means are arranged for detecting the high-frequency voltage drop across the sensor in synchronism with the high-frequency. Comparison means are provided for comparing the value of the said voltage drop to a reference voltage and producing a control signal depending on the condition of the sensor.
Claims5
An electronic watch control device for manual actuation comprising a capacitive sensor which includes a conductive layer applied on at least a part of the inner surface of the watch-glass and the capacitance of which with respect to ground as represented by the watch-case varies when the user puts a finger on the watch-glass, the said sensor being part of a capacitive voltage divider, the control device further comprising means for applying to the said capacitive voltage divider an a.c. voltage of a substantially higher frequency than the mains frequency, synchroneous detection means for detecting the high-frequency voltage across the said capacitive sensor,
- wherein the synchroneous detection means include a switching device connected to the terminals of the capacitive sensor and controlled by the said high frequency so as to alternately shot-circuit the sensor and apply the voltage appearing at the terminals of the sensor to a low-pass filter, and comparison means for comparing the value of the said high frequency voltage to a reference voltage, said comparison means being adapted for producing a control signal depending on whether or not the sensor is actuated by placing a finger-tip on the watch-glass.
An electronic watch control device for manual actuation comprising a capacitive sensor which includes a conductive layer applied on at least a part of the inner surface of the watch-glass and the capacitance of which with respect to ground as represented by the watch-case varies when the user puts a finger on the watch-glass, the said sensor being part of a capacitive voltage divider, the control device further comprising means for applying to the said capacitive voltage divider an a.c. voltage of a substantially higher frequency than the mains frequency, synchroneous detection means for detecting the high-frequency voltage across the said capacitive sensor,
- a capacitive reference voltage divider including a capacitor constructed similarly to the sensor capacitor but being arranged such that the reference voltage divider presents a fixed capacitance ratio, and means for applying the said a.c. voltage to the reference voltage divider, and comparison means for comparing the value of the said high frequency voltage to a reference voltage, said comparison means being adapted for producing a control signal depending on whether or not the sensor is actuated by placing a finger-tip on the watch-glass.
An electronic watch control device for manual actuation comprising a capacitive sensor which includes a conductive layer applied on at least a part of the inner surface of the watch-glass and the capacitance of which with respect to ground as represented by the watch-case varies when the user puts a finger on the watch-glass, the said sensor being part of a capacitive voltage divider, the control device further comprising means including the clock signal generator of the watch for applying to the said capacitive voltage divider an a.c. voltage of a substantially higher frequency than the mains frequency, synchronous detection means for detecting the high-frequency voltage drop across the said capacitive sensor, said synchronous detection means including a switching device connected to the terminals of the capacitive sensor and controlled by the said high frequency so as to alternately short-circuit the sensor and apply the voltage appearing at the terminals of the sensor to a low-pass filter, said switching device being an insulated-gate field-effect transistor the conduction path of which is connected in parallel with the sensor, and comparison means for comparing the value of said high frequency voltage to a reference voltage, said comparison means being adapted for producing a control signal depending on whether or not the sensor is actuated by placing a finger-tip on the watch-glass.
An electronic watch control device for manual actuation comprising a capacitive sensor which includes a conductive layer applied on at least a part of the inner surface of the watch-glass and the capacitance of which with respect to ground as represented by the watch-case varies when the user puts a finger on the watch-glass, the said sensor being part of a capacitive voltage divider, the control device further comprising means for applying to the said capacitive voltage divider an a.c. voltage of a substantially higher frequency than the mains frequency, synchroneous detection means for detecting the high-frequency voltage across the said capacitive sensor, and comparison means for comparing the value of the said high frequency, voltage to a reference voltage, said comparison means being adapted for producing a control signal depending on whether or not the sensor is actuated by placing a finger-tip on the watch-glass, the control device controlled by a quartz crystal including a generator of clock pulses, comprising means for producing a reference voltage, said means including a memory device for storing the voltage across the sensor during the non-actuated state thereof and means for periodically readjusting the level of the reference voltage under the control of the said clock pulses.
Dependencies are inferred from the claim text.