Method and apparatus for detecting a touch position, and touchscreen display apparatus having the same

• US 8,988,360 B2
• Filed: 06/02/2009
• Issued: 03/24/2015
• Est. Priority Date: 12/24/2008
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Inventors: Takahashi, Seiki, Saito, Satoru, Kim, Sang-Soo, You, Bong-Hyun, Lee, Byoung-Jun, Koh, Jai-Hyun
• Primary Examiner(s): Boddie, William
• Assistant Examiner(s): Shapiro, Leonid
• Application Number:
  US12/476,805
• Publication Number:
  US 20100156819A1
• Time in Patent Office: 2,121 Days
• Field of Search: 345173-176, 345/104
• US Class Current: 345/173
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/0447 Position sensing using the local deformation of sensor cells

Abstract

A method for detecting a touch position includes integrating a readout current detected at a sensing part to generate an integrated readout voltage, converting the integrated readout voltage into a digital converted readout voltage data and compensating a variation of the digital converted readout voltage data to determine whether the sensing part is touched.

Claims

1. A method for detecting a touch position, the method comprising:

integrating a readout current detected at a sensing part to generate an integrated readout voltage;

converting the integrated readout voltage into a digital converted readout voltage data;

compensating a variation of the digital converted readout voltage data to determine whether the sensing part is touched based on a difference between a current data corresponding to the digital converted readout voltage data and a reference data with a threshold data, wherein the current data is rewritten as the reference data when the difference between the current data and the reference data is substantially greater than a positive touch threshold data; and

adjusting a reset voltage provided to a reset transistor of the sensing part to generate an adjusted reset voltage,

wherein the adjusting the reset voltage comprises;

calculating a current reset adjustment voltage bases on an average value of a reference data;

dividing a voltage in response to the current reset adjustment voltage to generate a divided voltage; and

providing the reset transistor with the reset voltage in response to the divided voltage,

wherein the calculating the current reset adjustment voltage is performed based on;

VR(n)=VR(n−

1)+(A(r)−

D(T))×

a,

wherein VR(n) is the current reset adjustment voltage, VR(n−

1) is a previous reset adjustment voltage, A(r) is an average value of a whole reference data, D(T) is target reference data, and a is a compensation coefficient.

2. An apparatus for detecting a touch position, the apparatus comprising:

an integrator which integrates a readout current detected at a sensing part to generate an integrated readout voltage;

an analog-to-digital converter which converts the integrated readout voltage into a digital converted readout voltage data; and

a digital processing circuit which compensates a variation of the digital converted readout voltage data to determine whether the sensing part is touched, based on a difference between a current data corresponding to the digital converted readout voltage data and a reference data with a threshold data, wherein the current data is rewritten as the reference data when the difference between the current data and the reference data is greater than a positive reset threshold data,

wherein the sensing part comprises;

a reference capacitor connected to a previous gate line through a first terminal thereof;

a sensing capacitor having a capacitance which varies based on a touch operation;

a writing transistor comprising;

a gate connected to a first terminal of the sensing capacitor and a second terminal of the reference capacitor;

a source connected to a bias voltage line which transmits a bias voltage; and

a drain connected to a sensing voltage line which transmits a sensing voltage; and

a reset transistor comprising;

a gate connected to a current gate line;

a source connected to a reset voltage line which transmits a reset voltage; and

a drain connected to a first terminal of the sensing capacitor, a second terminal of the reference capacitor and a gate of the writing transistor.

3. The apparatus of claim 2, wherein the digital processing circuit comprises:

a reference data memory which stores the reference data;

a control signal generating part which provides the integrator with a reset signal and the analog-to-digital converter with a latch pulse; and

a digital comparator which compares a difference between a current data provided from the analog-to-digital converter and a reference data provided from the reference data memory with the threshold data in response to a control signal provided from the control signal generating part to discriminate whether a touch operation is performed.

4. The apparatus of claim 3, wherein a bit-depth of digital converted readout voltage data outputted from the analog-to-digital converter and the reference data is in a range from four bits to six bits.

5. The apparatus of claim 3, wherein the digital comparator rewrites the current data as the reference data in the reference data memory when the difference between the current data and the reference data is less than a negative reset threshold data.

6. The apparatus of claim 3, wherein the digital comparator outputs a touch discrimination data when the difference between the current data and the reference data is greater than the positive reset threshold data.

7. The apparatus of claim 6, further comprising a touch data memory which stores the touch discrimination data provided from the digital comparator and maintains one of a touch state and a non-touch state based on the touch discrimination data provided from the digital comparator during a predetermined frame.

8. The apparatus of claim 3, wherein the reference data is rewritten based on a start operation.

9. The apparatus of claim 3, wherein the digital processing circuit determines the touch state is performed when the difference between the current data and the reference data is greater than the positive reset threshold data.

10. The apparatus of claim 3, wherein

the sensing part further comprises groups of sensing pixels corresponding to digital comparators of a plurality of the digital comparators, and

the digital processing circuit further comprises a spatial filter which receives one of a touch signal and a non-touch signal provided from each of the digital comparators to discriminate whether a corresponding group of sensing pixels is in one of a touch state and a non-touch state, respectively.

11. The apparatus of claim 2, further comprising a reset voltage adjusting part which adjusts a reset voltage provided to the reset transistor.

12. The apparatus of claim 11, wherein the reset voltage adjusting part comprises:

a calculating part which calculates a current reset adjustment voltage based on an average value of a whole reference data stored in the reference data memory;

a voltage dividing part which divides a voltage in response to the current reset adjustment voltage provided from the calculating part; and

a buffer amplifier which provides the reset transistor with an adjusted reset voltage adjusted in response to a divided voltage provided from the voltage dividing part.

13. The apparatus of claim 12, wherein the calculating part provides the voltage dividing part with the current reset adjustment voltage based on:

VR(n)=VR(n−

1)+(A(r)−

D(T))×

a,

wherein VR(n) is the current reset adjustment voltage, VR(n−

1) is a previous reset adjustment voltage, A(r) is an average value of a whole reference data, D(T) is target reference data, and “

a”

is a compensation coefficient.

14. A touchscreen display apparatus comprising:

a liquid crystal display panel comprising;

a touchscreen display substrate including a pixel array and a sensing array;

an opposite substrate disposed opposite to the touchscreen display substrate;

and

a liquid crystal layer interposed between the touchscreen display substrate and the opposite substrate; and

a touch position detection apparatus comprising;

an integrator which integrates a readout current detected at a sensing part to generate an integrated readout voltage;

an analog-digital converter which converts the integrated readout voltage into a digital converted readout voltage data; and

a digital processing circuit which compensates a variation of the digital converted readout voltage data to determine whether the sensing part is touched, based on a difference between a current data corresponding to the digital converted readout voltage data and a reference data with a threshold data, wherein the current data is rewritten as the reference data when the difference between the current data and the reference data is greater than a positive reset threshold data,

wherein the sensing part comprises;

a reference capacitor connected to a previous gate line through a first terminal thereof;

a sensing capacitor having a capacitance which varies based on a touch operation;

a writing transistor comprising;

a gate connected to a first terminal of the sensing capacitor and a second terminal of the reference capacitor;

a source connected to a bias voltage line which transmits a bias voltage; and

a drain connected to a sensing voltage line which transmits a sensing voltage; and

a reset transistor comprising;

a gate connected to a current gate line;

a source connected to a reset voltage line which transmits a reset voltage; and

a drain connected to a first terminal of the sensing capacitor, a second terminal of the reference capacitor and a gate of the writing transistor.