Signal processing device of touch panel

A signal processing device of a touch panel comprising a first touch pad, a second touch pad and an excitation pad disposed between the first touch pad and the second touch pad, the signal processing device comprising:

• an alternating current power supply providing the excitation pad with an alternating voltage;
• an electric charge amplifier generating a voltage corresponding to a difference between a first capacitance of a first capacitor formed between the first touch pad and the excitation pad and a second capacitance of a second capacitor formed between the second touch pad and the excitation pad;
• and
• a third capacitor and a fourth capacitor, wherein
• the electric charge amplifier comprises a differential amplifier comprising a first input terminal and a second input terminal, the first input terminal being connected to a connecting node between the first touch pad and the third capacitor, and the second input terminal being connected to a connecting node between the second touch pad and the fourth capacitor.

A signal processing device comprising:

• a touch panel comprising,
• a plurality of pairs of touch pads, each of the touch pads being a first kind of touch pad, a second kind of touch pad, a third kind of touch pad or a fourth kind of touch pad, and each of the pairs of touch pads comprising two touch pads of a single kind or two touch pads of two different kinds, and
• an excitation pad disposed between neighboring two of the pairs of touch pads;
• and
• a signal processing device of the touch panel comprising,
• an alternating current power supply providing the excitation pad with an alternating voltage,
• a selection circuit selecting in turn a combination of the first kind of touch pads and the second kind of touch pads and a combination of the third kind of touch pads and the fourth kind of touch pads, and
• an electric charge amplifier generating a voltage corresponding to a difference between a first capacitance of a first capacitor formed between the excitation pad and one kind of touch pads in the combination selected by the selection circuit and a second capacitance of a second capacitor formed between the excitation pad and the other kind of touch pads in the combination selected by the selection circuit.

A signal processing device comprising:

• a touch panel comprising,
• a plurality of pairs of touch pads, each of the touch pads being one of n kinds of touch pads, n being an even integer equal to or larger than four, and each of the pairs of touch pads comprising two touch pads of a single kind or two touch pads of two different kinds, and
• an excitation pad disposed between neighboring two of the pairs of touch pads;
• and
• a signal processing device of the touch panel comprising,
• an alternating current power supply providing the excitation pad with an alternating voltage,
• a selection circuit selecting in turn two kinds of touch pads as a combination out of predetermined n/2 combinations of n kinds of touch pads, each of the n/2 combinations of touch pads comprising two of the n kinds of touch pads, and
• an electric charge amplifier generating a voltage corresponding to a difference between a first capacitance of a first capacitor formed between the excitation pad and one kind of touch pads in the combination selected by the selection circuit and a second capacitance of a second capacitor formed between the excitation pad and the other kind of touch pads in the combination selected by the selection circuit.