Touch sensing system

Patent metadata

Field	Value
Publication number	US-9465497-B2
Application number	US-201414478196-A
Country	US
Kind code	B2
Filing date	Sep 5, 2014
Priority date	Dec 31, 2013
Publication date	Oct 11, 2016
Grant date	Oct 11, 2016

Abstract

A touch sensing system includes a plurality of touch sensors, sensing lines connected to the touch sensors, a touch sensing integrated circuit (IC) sensing a touch input using signals received through a plurality of receiving channels, a plurality of differential amplifiers which are formed between the sensing lines and the receiving channels of the touch sensing IC and amplify a difference between touch sensor signals received through adjacent sensing lines, and a multiplexer which connects the adjacent sensing lines to input terminals of each differential amplifier in a forward sensing mode and switches the adjacent sensing lines connected to the input terminals of each differential amplifier in a reverse sensing mode.

First claim

What is claimed is:

1. A touch sensing system, comprising:
a plurality of touch sensors;
sensing lines connected to the touch sensors;
a touch sensing integrated circuit (IC) configured to sense a touch input using signals received through a plurality of channels;
a plurality of differential amplifiers formed between the sensing lines and the channels of the touch sensing IC, each of the plurality of differential amplifiers configured to amplify a difference between touch sensor signals received through adjacent sensing lines; and
a multiplexer configured to connect the adjacent sensing lines to input terminals of each differential amplifier in a forward sensing mode and switch the adjacent sensing lines connected to the input terminals of each differential amplifier in a reverse sensing mode,
wherein the touch sensing IC comprises an integrator connected to the differential amplifiers, an analog-to-digital converter (ADC) converting an output voltage of the integrator into a touch raw data, and a memory to which the touch raw data is stored, and
wherein the touch sensing IC ignores touch raw data of signal received from at least one channel, and combines touch raw data obtained from the forward sensing mode and the reverse sensing mode based on the number of channels.

2. The touch sensing system of claim 1 , wherein the touch sensing IC ignores an output signal having a low signal-to-noise ratio among output signals of the differential amplifiers received in the forward sensing mode and output signals of the differential amplifiers received in the reverse sensing mode and senses the touch input based on the remaining output signals.

3. The touch sensing system of claim 2 ,
wherein the touch sensing IC ignores one of an output signal of a first differential amplifier connected to a first channel and an output signal of an Nth differential amplifier connected to an Nth channel corresponding to a last channel, where N is a positive integer equal to or greater than 2.

4. The touch sensing system of claim 3 , wherein each differential amplifier includes an inverting input terminal, a non-inverting input terminal, an output terminal, and a capacitor connected between the inverting input terminal and the output terminal,
wherein an inverting input terminal and a non-inverting input terminal of each of other differential amplifiers except the Nth differential amplifier are connected to adjacent sensing lines, and one input terminal of the Nth differential amplifier is not connected to any sensing line.

5. The touch sensing system of claim 4 , wherein the touch sensing IC ignores an output of the Nth differential amplifier and calculates coordinates of a position of the touch input based on sensing results obtained by combining touch raw data obtained from an output of the other differential amplifiers based on the number of channels.

6. The touch sensing system of claim 3 , wherein in the forward sensing mode, an inverting input terminal of each of other differential amplifiers except the Nth differential amplifier is connected to an ith sensing line, and a non-inverting input terminal of each of the other differential amplifiers except the Nth differential amplifier is connected to an (i+1)th sensing line, where ‘i’ is a positive integer,
wherein in the reverse sensing mode, the inverting input terminal of each of the other differential amplifiers except the Nth differential amplifier is connected to the (i+1)th sensing line, and the non-inverting input terminal of each of the other differential amplifiers except the Nth differential amplifier is connected to the ith sensing line,
wherein in the forward sensing mode, an inverting input terminal of the Nth differential amplifier is connected to an Nth sensing line, and a non-inverting input terminal of the Nth differential amplifier is not connected to any sensing line,
wherein in the reverse sensing mode, the inverting input terminal of the Nth differential amplifier is not connected to any sensing line, and the non-inverting input terminal of the Nth differential amplifier is connected to the Nth sensing line.

7. The touch sensing system of claim 3 , further comprising a second multiplexer configured to shift the sensing lines connected to the input terminals of the differential amplifiers.

8. The touch sensing system of claim 7 , wherein in a first time of the forward sensing mode, an inverting input terminal of each of other differential amplifiers except the Nth differential amplifier is connected to an ith sensing line, and a non-inverting input terminal of each of the other differential amplifiers except the Nth differential amplifier is connected to an (i+1)th sensing line, where ‘i’ is a positive integer,
wherein in a second time of the forward sensing mode, the inverting input terminal of each of the other differential amplifiers except the Nth differential amplifier is connected to the (i+1)th sensing line, and the non-inverting input terminal of each of the other differential amplifiers except the Nth differential amplifier is connected to an (i+2)th sensing line,
wherein in a first time of the reverse sensing mode, the inverting input terminal of each of the other differential amplifiers except the Nth differential amplifier is connected to the (i+1)th sensing line, and the non-inverting input terminal of each of the other differential amplifiers except the Nth differential amplifier is connected to the ith sensing line,
wherein in a second time of the reverse sensing mode, the inverting input terminal of each of the other differential amplifiers except the Nth differential amplifier is connected to the (i+2)th sensing line, and the non-inverting input terminal of each of the other differential amplifiers except the Nth differential amplifier is connected to the (i+1)th sensing line,
wherein in the first time of the forward sensing mode, an inverting input terminal of the Nth differential amplifier is connected to an (N−1)th sensing line, and a non-inverting input terminal of the Nth differential amplifier is connected to an Nth sensing line,
wherein in the second time of the forward sensing mode, the inverting input terminal of the Nth differential amplifier is connected to the Nth sensing line, and the non-inverting input terminal of the Nth differential amplifier is not connected to any sensing line,
wherein in the first time of the reverse sensing mode, the inverting input terminal of the Nth differential amplifier is connected to the Nth sensing line, and the non-inverting input terminal of the Nth differential amplifier is connected to the (N−1)th sensing line,
wherein in the second time of the reverse sensing mode, the inverting input terminal of the Nth differential amplifier is not connected to any sensing line, and the non-inverting input terminal of the Nth differential amplifier is connected to the Nth sensing line.

9. The touch sensing system of claim 8 , wherein the touch sensing IC ignores an output of the Nth differential amplifier and calculates coordinates of a position of the touch input based on sensing results obtained by combining touch raw data obtained from an output of the other differential amplifiers based on the number of channels.

10. The touch sensing system of claim 7 , wherein each differential amplifier includes an inverting input terminal, a non-inverting input terminal, an output terminal, and a capacitor connected between the inverting input terminal and the output terminal,
wherein the inverting input terminal and the non-inverting input terminal of each of other differential amplifiers except a first differential amplifier connected to a first receiving channel of the touch sensing IC among the differential ampli

Assignees

• Lg Display Co Ltd

Inventors

• Han Sungsu
• Kang Seongkyu

Classifications

• G06F3/0418 Primary

  for error correction or compensation, e.g. based on parallax, calibration or alignment · CPC title

• G06F3/044 Primary

  by capacitive means · CPC title

• G06F3/04182 Primary

  Filtering of noise external to the device and not generated by digitiser components · CPC title

• G06F3/0446

  using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes · CPC title

• G06F3/0443

  using a single layer of sensing electrodes · CPC title