TOUCH SCREEN DRIVER

• US 20140354592A1
• Filed: 05/30/2014
• Published: 12/04/2014
• Est. Priority Date: 05/31/2013
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: Kang, Hyeongwon, Kim, Beomjin
• Granted Patent: US 9,965,109 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 3/04182 Filtering of noise external to the device and not generated by digitiser components
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes

Abstract

A touch screen driver includes a touch screen comprising Tx channels, Rx channels crossing the Tx channels, and sensor nodes formed at the crossings of the Tx channels and the Rx channels; a Tx driving circuit for supplying a Tx driving pulse to the Tx channels; an Rx driving circuit comprising an offset charge compensation circuit that equally compensates for the amount of offset charge included in the voltages of the sensor nodes supplied through the Rx channels and a sampling circuit that samples the offset-compensated voltages of the sensor nodes in response to an Rx sampling clock and converts the sampled voltages into digital data; and a touch controller that analyzes the digital data input from the Rx driving circuit by a preset touch recognition algorithm and outputs touch data including coordinate information of a touch position.

Claims

1. A touch screen driver, comprising:

a touch screen comprising Tx channels, Rx channels crossing the Tx channels, and sensor nodes formed at the crossings of the Tx channels and the Rx channels;

a Tx driving circuit for supplying a Tx driving pulse to the Tx channels;

an Rx driving circuit comprising an offset charge compensation circuit that equally compensates for the amount of offset charge included in the voltages of the sensor nodes supplied through the Rx channels and a sampling circuit that samples the offset-compensated voltages of the sensor nodes in response to an Rx sampling clock and converts the sampled voltages into digital data; and

a touch controller that analyzes the digital data input from the Rx driving circuit by a preset touch recognition algorithm and outputs touch data including coordinate information of a touch position.

2. The touch screen driver of claim 1, wherein the offset charge compensation circuit is connected on a one-to-one basis to each Rx channel or connected to a plurality of Rx channels.

3. The touch screen driver of claim 2, wherein the offset charge compensation circuit comprises:

an input terminal into which a compensation pulse having the opposite phase to that of a Tx driving pulse is input;

a plurality of compensation capacitors connected in parallel to the input terminal; and

a plurality of switches, one end of which being connected in series to the compensation capacitors and the other end of which being connected commonly to at least one of the Rx channels,

wherein the amount required to compensate for the amount of offset charge by a predetermined reference value is determined depending on the number of switches to be conducted among the switches.

4. The touch screen driver of claim 3, wherein the switches are switched on or off according to a predetermined charge control register value based on parameter information on the touch screen.

5. The touch screen driver of claim 3, wherein the amount of compensation varies with a touch position on the touch screen.

6. The touch screen driver of claim 5, wherein the offset charge compensation circuit further comprises a level shifter that is connected between the input terminal and the compensation capacitors and level-shifts the amplitude of the compensation pulse.