Semiconductor Components Industries, LLC

Sanyo Semiconductor Co., Ltd.

Kumiko Fukai

Kazuyuki Kobayashi

Tatsuya Suzuki

Yasuhiro Kaneta

There is offered a signal processing circuit for an electrostatic capacity type touch sensor which can improve the noise tolerance and adjust an offset in the output voltage. The signal processing circuit for the touch sensor is structured to include an alternating current power supply providing an excitation pad with an alternating voltage, an electric charge amplifier generating an output voltage Vout corresponding to a difference between a capacitance of a first capacitor formed between a first touch pad and the excitation pad and a capacitance of a second capacitor formed between a second touch pad and the excitation pad, and an offset adjustment circuit to adjust an offset in the output voltage Vout of the electric charge amplifier.

Signal processing circuit for electrostatic capacity type touch sensor

There is offered a signal processing circuit of the electrostatic capacity type touch panel which can eliminate duplication of components to reduce a cost of the components. A touch panelis formed on a glass substrate. Sensor circuitsA andB are arrayed in a Y direction, and sensor circuitsC andD are arrayed in an X direction on the periphery of the touch pane. Serial clock terminals SCL of the sensor circuitsA-D are connected to a serial clock lineall together, while serial data terminals SDA are connected to a serial data lineall together. A microcomputeris disposed on a PCB substrate outside the glass substrate. Data communication can be performed between the microcomputerand the sensor circuitsA-D through the serial clock lineand the serial data line

Capcitive touch panel with simultaneously enabled X- and Y-direction sensor circuits wherein in each sensor circuit the drive line is interdigitated with a plurality of sense lines

There is offered a signal processing circuit for an electrostatic capacity type touch sensor capable of detecting a larger number of locations with a smaller number of touch pads as well as improving noise immunity. A selection circuit selects either a signal from a combination of the first and second kinds of touch pads outputted through the first and second output terminals COand COin a touch panel or a signal from a combination of the third and fourth kinds of touch pads outputted through the third and fourth output terminals COand CO. An electric charge amplifier outputs first and second output voltages Vand Vcorresponding to a difference between capacitances of the touch pads on the touch panel based on the signals from the selected combination. A delta sigma type A/D converter converts the first and second output voltages Vand Vinto digital signals.

The invention realizes certainly detecting two or more positions on a touch panel that are touched at the same time. A drive circuit selects one from X lines, and supplies an alternating drive voltage to the selected line. A multiplexer selects a first sense line and a second sense line from Y lines that extend to cross the X lines. A charge amplifier outputs an output voltage corresponding to a difference between a first capacitance between the first sense line and the X line selected by the drive circuit and a second capacitance between the second sense line and the X line selected by the drive circuit. A touch position is then detected based on the output voltage of the charge amplifier.

Signal processing circuit for electrostatic capacitor type touch sensor

There is offered a signal processing device of touch panel using an electrostatic capacity, which realizes improvement in noise tolerance and linear detection. An excitation pad, a first touch pad and a second touch pad are disposed on a substrate in a way that the excitation pad is interposed between the first and second touch pads. On the other hand, an alternating current power supply that provides the excitation pad with an alternating voltage through a wiring is provided on a sensor IC side of the signal processing device of touch panel. Also, there is provided an electric charge amplifier. The first touch pad is connected to a non-inverting input terminal (+) of the electric charge amplifier through an wiring, while the second touch pad is connected to an inverting input terminal (&#x2212;) of the electric charge amplifier through a wiring.

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Ora-gun, Japan

Kumiko Fukai