US 8,274,489 B2Granted

Readout apparatus and multi-channel readout apparatus for touch panel

AssigneeHimax Technologies Limited

InventorsKai-Lan Chuang, Guo-Ming Lee, Ying-Lieh Chen

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Abstract

A readout apparatus and a multi-channel readout apparatus for a touch panel are provided to integrate different types of readout circuit. The readout apparatus set to a first mode reads the touch panel with a small amount of charges through an integrator. The readout apparatus set to a second mode reads a sensing current of a current type touch panel through a current to voltage converting unit and an inverting amplifier, so as to save a chip area. The multi-channel readout apparatus set to a third mode applies multiple channels to alternatively share an integrator to read the touch panel with a large amount of charges, so that an amount of feedback capacitors (integral capacitors) having a great area can be greatly reduced. Therefore, readout apparatus of the present invention can not only reduce a chip area, but can also be applied to various types of the touch panel.

Claims25

Dependent claims

A readout apparatus for a touch panel, comprising:

a first selector, having a common terminal electrically connected to a first selection terminal or a second selection terminal, selectively;
a current to voltage converting unit, having an input terminal coupled to the first selection terminal of the first selector;
a first resistor, having a first terminal coupled to an output terminal of the current to voltage converting unit;
a second selector, having a common terminal electrically connected to a first selection terminal or a second selection terminal, selectively, wherein the first selection terminal of the second selector is coupled to a second terminal of the first resistor, and the second selection terminal of the second selector is coupled to the second selection terminal of the first selector;
a first operation amplifier, having a first input terminal coupled to the common terminal of the second selector, and a second input terminal receiving a first reference voltage;
a third selector, having a common terminal electrically connected to a first selection terminal or a second selection terminal, selectively, wherein the common terminal of the third selector is coupled to the first input terminal of the first operation amplifier;
a fourth selector, having a common terminal electrically connected to a first selection terminal or a second selection terminal, selectively, wherein the common terminal of the fourth selector is coupled to an output terminal of the first operation amplifier;
a second resistor, having a first terminal coupled to the first selection terminal of the third selector, and a second terminal coupled to the first selection terminal of the fourth selector;
a feedback capacitor, having a first terminal coupled to the second selection terminal of the third selector, and a second terminal coupled to the second selection terminal of the fourth selector;
and
a feedback switch, having a first terminal and a second terminal respectively coupled to the first terminal and the second terminal of the feedback capacitor.

8 more elements

A multi-channel readout apparatus for a touch panel, comprising:

an integrator;
and
a plurality of channels, and each of the channels comprising:
an input selector, having a common terminal electrically connected to a first selection terminal or a second selection terminal, selectively, wherein the first selection terminal of the input selector is coupled to an input terminal of the integrator;
a first selector, having a common terminal electrically connected to a first selection terminal or a second selection terminal, selectively, wherein the common terminal of the first selector is coupled to the second selection terminal of the input selector;
a current to voltage converting unit, having an input terminal coupled to the first selection terminal of the first selector;
a first resistor, having a first terminal coupled to an output terminal of the current to voltage converting unit;
a second selector, having a common terminal electrically connected to a first selection terminal or a second selection terminal, selectively, wherein the first selection terminal of the second selector is coupled to a second terminal of the first resistor, and the second selection terminal of the second selector is coupled to the second selection terminal of the first selector;
a first operation amplifier, having a first input terminal coupled to the common terminal of the second selector, and a second input terminal receiving a first reference voltage;
a third selector, having a common terminal electrically connected to a first selection terminal or a second selection terminal, selectively, wherein the common terminal of the third selector is coupled to the first input terminal of the first operation amplifier;
a fourth selector, having a common terminal electrically connected to a first selection terminal or a second selection terminal, selectively, wherein the common terminal of the fourth selector is coupled to an output terminal of the first operation amplifier;
a second resistor, having a first terminal coupled to the first selection terminal of the third selector, and a second terminal coupled to the first selection terminal of the fourth selector;
a feedback capacitor, having a first terminal coupled to the second selection terminal of the third selector, and a second terminal coupled to the second selection terminal of the fourth selector;
a feedback switch, having a first terminal and a second terminal respectively coupled to the first terminal and the second terminal of the feedback capacitor;
and
an output selector, having a common terminal electrically connected to a first selection terminal or a second selection terminal, selectively, wherein the first selection terminal of the output selector is coupled to an output terminal of the integrator, and the second selection terminal of the output selector is coupled to the output terminal of the first operation amplifier.

13 more elements

Dependencies are inferred from the claim text.