TOUCH SCREEN SENSING DEVICE AND METHOD FOR SENSING TOUCH SCREEN

• US 20130141372A1
• Filed: 11/29/2012
• Published: 06/06/2013
• Est. Priority Date: 12/05/2011
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: Kang, Hyeongwon
• Granted Patent: US 9,519,364 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• CPC Class Codes: G06F 3/041 Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
• 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 sensing device includes a touch screen including touch sensors formed at crossings of Tx lines and Rx lines, a Tx driving circuit supplying a driving pulse to each of the Tx lines N times, and an Rx driving circuit which samples a signal voltage of the touch sensors received through the Rx lines and converts the sampled signal voltage into digital data. The Rx driving circuit includes a differential amplifier differentially amplifying signals received through the Rx lines, a low pass filter removing a radio frequency noise from an output of the differential amplifier, an amplifier amplifying an output of the low pass filter, and an integrator accumulating signal voltages which are successively output from the amplifier.

Claims

1. A touch screen sensing device comprising:

a touch screen including Tx lines, Rx lines crossing the Tx lines, and touch sensors formed at crossings of the Tx lines and the Rx lines;

a Tx driving circuit configured to supply a driving pulse to each of the Tx lines N times, where N is a positive integer equal to or greater than 2; and

an Rx driving circuit configured to sample a signal voltage of the touch sensors received through the Rx lines and convert the sampled signal voltage into digital data,

wherein the Rx driving circuit includes;

a differential amplifier configured to differentially amplify signals received through the adjacent Rx lines;

a low pass filter configured to remove a radio frequency noise from an output of the differential amplifier;

an amplifier configured to amplify an output of the low pass filter; and

an integrator configured to accumulate signal voltages which are successively output from the amplifier.

2. The touch screen sensing device of claim 1, wherein the Rx driving circuit further includes:

a sampling circuit configured to sample an output of the integrator; and

an analog to digital converter configured to convert the signal voltage sampled by the sampling circuit into digital data.

3. The touch screen sensing device of claim 2, wherein the differential amplifier, the low pass filter, the amplifier, and the sampling circuit each include a fully differential amplifier, which inputs and outputs voltages of a positive signal and a negative signal.

4. The touch screen sensing device of claim 2, further comprising a multiplexer that time-divides signals received through the Rx lines, and supplies the signals to both input terminals of the differential amplifier,

wherein the multiplexer supplies signals received from first and second Rx lines to the differential amplifier during a first frame period, and then supplies signals received from the second Rx line and a third Rx line to the differential amplifier during a second frame period.

5. A method for sensing a touch screen including Tx lines, Rx lines crossing the Tx lines, and touch sensors formed at crossings of the Tx lines and the Rx lines, the method comprising:

supplying a driving pulse to each of the Tx lines N times, where N is a positive integer equal to or greater than 2;

differentially amplifying signals received through the adjacent Rx lines;

removing a radio frequency noise from an output of a differential amplifier using a low pass filter;

amplifying an output of the low pass filter; and

successively receiving amplified signals to accumulate the amplified signals.

6. The method of claim 5, further comprising:

sampling an accumulated integration output; and

converting a sampled signal voltage into digital data.