TOUCH SENSING APPARATUS AND METHOD

• US 20140176489A1
• Filed: 11/21/2013
• Published: 06/26/2014
• Est. Priority Date: 12/26/2012
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: PARK, Dong-Jo
• Granted Patent: US 10,152,179 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/04166 Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184
• 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 apparatus and method for correctly sensing a touch signal by removing an offset per touch node via differential sensing are discussed. The touch sensing method includes sensing a first sensing value including an offset component per touch node using a read out signal of a touch sensor, the touch sensor not being supplied with a driving pulse, in a first sensing period; sensing a second sensing value including the offset component of the touch node and a mutual capacitive component based on whether a touch is performed, using a read out signal of the touch sensor, the touch sensor being supplied with a driving pulse, in a second sensing period; and acquiring touch data from which the offset component is removed via a differential operation of the second sensing value and the first sensing value.

Claims

1. A touch sensing method, comprising:

sensing a first sensing value including an offset component per touch node using a read out signal of a touch sensor, the touch sensor not being supplied with a driving pulse, in a first sensing period;

sensing a second sensing value including the offset component of the touch node and a mutual capacitive component based on whether a touch is performed, using a read out signal of the touch sensor, the touch sensor being supplied with a driving pulse, in a second sensing period; and

acquiring touch data from which the offset component is removed via a differential operation of the second sensing value and the first sensing value.

2. The method of claim 1, wherein the sensing in the first and second sensing periods of the touch node are performed consecutively.

3. The method of claim 1, further comprising:

integrating a first read out signal to output a first analog sensing signal, holding and sampling the first analog sensing signal to output the sampled and held first analog sensing signal, converting the first analog sensing signal into first digital sensing data to output the first digital sensing data, and inputting the first digital sensing data and storing the first digital sensing data in a buffer, in the first sensing period; and

integrating a second read out signal to output a second analog sensing signal, holding and sampling the second analog sensing signal to output the sampled and held second analog sensing signal, converting the second analog sensing signal into second digital sensing data to output the second digital sensing data, and performing subtraction on the second digital sensing data and the first digital sensing data from the buffer to acquire the touch data, in the second sensing period.

4. A touch sensing apparatus comprising:

a touch sensor for outputting a read out signal indicating capacitance change based on a presence of touch; and

a touch controller for sensing a first sensing value including an offset component per touch node using a read out signal of the touch sensor, the touch sensor not being supplied with a driving pulse in a first sensing period, sensing a second sensing value including the offset component of the touch node and a mutual capacitive component based on whether a touch is performed, using a read out signal of the touch sensor, the touch sensor being supplied with a driving pulse, in a second sensing period, and acquiring touch data from which the offset component is removed via a differential operation of the second sensing value and the first sensing value.

5. The touch sensing apparatus of claim 4, wherein the touch controller includes:

a control signal generator for generating and outputting a plurality of control signals;

a driving pulse generator for generating and outputting the driving pulse;

a touch sensor driver for not supplying the driving pulse from the driving pulse generator to a corresponding scan line of the touch sensor in the first sensing period and supplying the driving pulse to the corresponding scan line in the second sensing period in response to a control signal from the control signal generator; and

a read out circuit for sensing the first sensing value using a first read out signal from a corresponding read out line of the touch sensor in the first sensing period and sensing the second sensing value using a second read out signal from the corresponding read out line in the second sensing period in response to the control signal from the control signal generator, and then, acquiring and outputting the touch data via a differential operation of the first and second sensing values.

6. The touch sensing apparatus of claim 5, wherein the read out circuit includes:

an analog sensing unit for integrating the first read out signal to output a first analog sensing signal in the first sensing period, and integrating the second read out signal to output a second analog sensing signal in the second sensing period;

a sample and hold unit for holding and sampling the first analog sensing signal to output the sampled and held first analog sensing signal in the first sensing period, and holding and sampling the second analog sensing signal to output the sampled and held second analog sensing signal in the second sensing period;

a digital-to-analog converter for converting the first analog sensing signal from the sample and hold unit into first digital sensing data to output the first digital sensing data in the first sensing period, and converting the second analog sensing signal from the sample and hold unit into second digital sensing data to output the second digital sensing data in the second sensing period; and

a differential operator for inputting the first digital sensing data and storing the first digital sensing data in a buffer in the first sensing period, and performing subtraction on the second digital sensing data and the first digital sensing data from the buffer in the second sensing period to acquire the touch data.

7. The touch sensing apparatus of claim 4, wherein the touch sensor includes scan lines being allocated with a period including consecutive first and second sensing periods.