Touch screen sensing device and method for sensing touch screen

• US 9,519,364 B2
• Filed: 11/29/2012
• Issued: 12/13/2016
• Est. Priority Date: 12/05/2011
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: Kang, Hyeongwon
• Primary Examiner(s): Patel, Premal
• Assistant Examiner(s): Figueroa-Gibson, Gloryvid
• Application Number:
  US13/689,184
• Publication Number:
  US 20130141372A1
• Time in Patent Office: 1,475 Days
• Field of Search: 345156-184, 178 1801- 2003
• US Class Current: 1/1
• 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 touch screen panel (TSP) timing controller configured to generate a Tx setup signal for setting a Tx channel, a Rx setup signal for setting a Rx channel, and timing control signals for controlling operation timings;

a Tx driving circuit configured to select a Tx channel connected to each of the Tx lines in response to the Tx setup signal and 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 select a Rx channel connected to each of the Rx lines in response to the Rx setup signal, receive a signal voltage from the Rx line, sample the 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 plurality of differential amplifiers, each directly connected to two of the Rx lines which are adjacent to each other to differentially amplify signals received through the two of the Rx lines and output a positive signal and a negative signal having a potential difference corresponding to a difference between the signal voltages from the two of Rx lines

wherein each differentially amplified signal is processed through;

a low pass filter configured to remove a radio frequency noise from the positive signal and the negative signal output of the differential amplifiers;

an amplifier configured to amplify the positive signal and the negative signal from the low pass filter; and

an integrator configured to accumulate the positive signal and the negative signal 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 amplifiers, 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. 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:

generating a Tx setup signal for setting a Tx channel, a Rx setup signal for setting a Rx channel, and timing control signals for controlling operation timings;

selecting a Tx channel connected to each of the Tx lines in response to the Tx setup signal and supplying a driving pulse to each of the Tx lines N times, where N is a positive integer equal to or greater than 2;

an Rx channel connected to each of the Rx lines in response to the Rx setup signal;

the Rx channel amplifying signals using a differential amplifier always connected to each Rx line and an immediately adjacent Rx line so as to form pairs;

outputting a positive signal and a negative signal from the differential amplifier having a potential difference corresponding to a difference between the signals from the two of Rx lines of the pair of Rx lines;

removing a radio frequency noise from the positive signal and the negative signal output of a differential amplifier using a low pass filter;

amplifying the positive signal and the negative signal from the low pass filter; and

successively receiving the differentially amplified signals of the pair of Rx lines to accumulate the amplified signals.

5. The method of claim 4, further comprising:

sampling an accumulated integration output; and

converting a sampled signal voltage into digital data.

6. The method of claim 4, wherein the differential amplifier is directly connected to each Rx line and the immediately adjacent Rx line.