TOUCH SENSING DEVICE AND DOUBLE SAMPLING METHOD THEREOF

• US 20130249825A1
• Filed: 12/27/2012
• Published: 09/26/2013
• Est. Priority Date: 03/20/2012
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: Kang, Hyeongwon, Jun, Jaehun
• Granted Patent: US 9,134,824 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• CPC Class Codes: G06F 3/03547 Touch pads, in which fingers can move on a surface
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• 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 sensing device includes 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 for supplying a driving signal 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 for double sampling signals received through the Rx lines in one period of the driving signal. The Rx driving circuit includes a multiplexer which receives first and second signals and switches on or off a signal transmission path of the first and second signals, and an integrator which samples and integrates the first and second signals received from the multiplexer.

Claims

1. A touch 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 signal to each of the Tx lines; and

an Rx driving circuit configured to double sample signals received through the Rx lines in one period of the driving signal,

wherein the Rx driving circuit includes;

a multiplexer configured to receive first and second signals and switch on or off a signal transmission path of the first and second signals; and

an integrator configured to sample and integrate the first and second signals received from the multiplexer.

2. The touch sensing device of claim 1, wherein one period of the driving signal includes a high potential period and a low potential period,

wherein the multiplexer supplies the first signal to a first sampling capacitor and supplies the second signal to a second sampling capacitor during the high potential period of the driving signal, and

wherein the multiplexer supplies the second signal to the first sampling capacitor and supplies the first signal to the second sampling capacitor during the low potential period of the driving signal.

3. The touch sensing device of claim 2, wherein the integrator includes:

a first integral capacitor configured to accumulate positive voltages which are successively supplied from the first sampling capacitor twice in the one period of the driving signal;

a second integral capacitor configured to accumulate negative voltages which are successively supplied from the second sampling capacitor twice in the one period of the driving signal; and

a differential amplifier connected to the first and second integral capacitors,

wherein the first integral capacitor is connected between a first input terminal and a first output terminal of the differential amplifier,

wherein the second integral capacitor is connected between a second input terminal and a second output terminal of the differential amplifier.

4. The touch sensing device of claim 3, wherein the multiplexer switches on or off the signal transmission path in response to a MUX control signal,

wherein a period of the MUX control signal is substantially the same as a period of the driving signal, and a phase of the MUX control signal is later than a phase of the driving signal,

wherein the MUX control signal rises in the high potential period of the driving signal and falls in the low potential period of the driving signal.

5. The touch sensing device of claim 4, wherein the integrator includes:

a first switch which is connected between a node, between a first output terminal of the multiplexer and a first electrode of the first sampling capacitor, and a ground level voltage source and is turned on in response to a pulse of a second switch control signal;

a second switch which is connected between a second electrode of the first sampling capacitor and the ground level voltage source and is turned on in response to a pulse of a first switch control signal;

a third switch which is connected between the second electrode of the first sampling capacitor and the first input terminal of the differential amplifier and is turned on in response to the pulse of the second switch control signal;

a fourth switch which is connected between a node, between a second output terminal of the multiplexer and a first electrode of the second sampling capacitor, and the ground level voltage source and is turned on in response to the pulse of the second switch control signal;

a fifth switch which is connected between a second electrode of the second sampling capacitor and the ground level voltage source and is turned on in response to the pulse of the first switch control signal; and

a sixth switch which is connected between the second electrode of the second sampling capacitor and the second input terminal of the differential amplifier and is turned on in response to the pulse of the second switch control signal,

wherein the first and second switch control signals are out of phase with each other and have a frequency two times higher than the MUX control signal.

6. A double sampling method of a touch sensing device including 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 signal to each of the Tx lines; and

double sampling signals received through the Rx lines in one period of the driving signal,

wherein the double sampling of the received signals includes;

receiving first and second signals from a multiplexer and switching on or off a signal transmission path of the first and second signals; and

sampling and integrating the first and second signals using an integrator connected to the multiplexer.