Touch sensitive display device

Abstract

A liquid crystal display includes a first display panel, a second display panel, a liquid crystal layer, a plurality of sensing data lines formed on the second display panel, a plurality of variable capacitors connected to the sensing data lines and a first voltage of which capacitance is changed depending on pressure, a plurality of reference capacitors connected to the sensing data lines and a second voltage, and a plurality of output units connected to the sensing data lines which generate sensing signals on the basis of sensing data signals that flow through the sensing data lines. The magnitude of the first voltage has a first level and a second level that is different from the first level, and the magnitude of the second voltage is constant. A time period for maintaining the first voltage at the second level in a interval for reading the sensing signal is at least 1H, and the sensing signal is generated while maintaining the first voltage at the second level. Accordingly, a time for outputting the sensing signal is increased and sensitivity of the sensing unit is improved, thereby increasing reliability of the sensing signal.

Description

BRIEF DESCRIPTION OF THE DRAWING

The foregoing and other objects, features and advantages of the present invention will become more apparent from the ensuing description when read together with the drawing, in which:

FIG. 1 is a block diagram showing a liquid crystal display from a pixel point of view according to an embodiment of the present invention;

FIG. 2 is an equivalent circuit diagram showing a pixel of a liquid crystal display according to another embodiment of the present invention;

FIG. 3 is a block diagram showing a liquid crystal display from a sensing unit point of view according to another embodiment of the present invention;

FIG. 4 is an equivalent circuit diagram showing a sensing unit of a liquid crystal display according to another embodiment of the present invention;

FIG. 5 is a schematic diagram showing a liquid crystal display according to another embodiment of the present invention;

FIG. 6A is an equivalent circuit diagram showing a plurality of sensing units connected to a sensing data line in a liquid crystal display according to another embodiment of the present invention;

FIG. 6B is an equivalent circuit diagram schematically showing FIG. 6A;

FIG. 7 is a timing diagram for a sensing operation of a liquid crystal display according to another embodiment of the present invention;

FIG. 8 is a waveform diagram of various common voltages for reading a sensing signal of a contact sensing unit and sensed signals dependent on the common voltages according to an embodiment of the present invention;

FIG. 9 is a waveform diagram of various common voltages for reading a sensing signal of a contact sensing unit and sensing signals dependent on the common voltages according to another embodiment of the present invention; and

FIGS. 10 to 12 show various examples in which horizontal output data lines OY₁ to OY_N and sensing signal output units connected thereto are disposed according to another embodiment of the present invention.

Claims

1. A liquid crystal display comprising: a first display panel;a second display panel facing the first display panel and spaced apart from the first display panel;a liquid crystal layer interposed between the first and second display panels;a plurality of sensing data lines formed on the second display panel;a plurality of variable capacitors connected to the sensing data lines and a first voltage, the variable capacitors having a capacitance that is changed depending on pressure;a plurality of reference capacitors connected to the sensing data lines and a second voltage; anda plurality of output units connected to the sensing data lines, the output units generating sensing signals on the basis of sensing data signals that flow through the sensing data lines,wherein the magnitude of the first voltage has a first level and a second level that is different from the first level, and the magnitude of the second voltage is constant, andwherein the time period for maintaining the first voltage at the second level in a interval for reading the sensing signal is at least 1H, and the sensing signal is generated while maintaining the first voltage at the second level.

2. The liquid crystal display of claim 1, wherein the second level is higher than the first level.

3. The liquid crystal display of claim 1, wherein the second level is lower than the first level.

4. The liquid crystal display of claim 1, wherein the first voltage is a common voltage.

5. The liquid crystal display of claim 4, wherein the interval for reading the sensing signal is a porch interval.

6. The liquid crystal display of claim 1, further comprising a plurality of reset signal input units connected to the sensing data lines, the reset signal input units receiving a reset voltage and applying the reset voltage to the sensing data lines.

7. The liquid crystal display of claim 6, wherein the reset signal input units connected to the sensing data lines each include a first reset switching element which applies the first reset voltage that is input depending on the first reset control signal to the connected sensing data line.

8. The liquid crystal display of claim 7, wherein the reset signal input units connected to the sensing data lines each further include a second reset switching element which applies the second reset voltage that is input depending on the second reset control signal to the connected sensing data line at a different time from that when the first reset voltage is applied.

9. The liquid crystal display of claim 1, further comprising a plurality of output transistors connected to the sensing data lines, each of the output transistors transmitting an output signal that is generated depending on the sensing data signal that flows through the sensing data line to the corresponding output unit.

10. A liquid crystal display comprising: a first display panel;a second display panel facing the first display panel and being spaced apart from the first display panel;a plurality of pixels formed between the first and second display panels;a plurality of first sensing units formed between the first and second display panels;a plurality of second sensing units formed between the first and second display panels;a plurality of first sensing data lines connected to the first sensing units, the first sensing data lines extending in the horizontal direction on the second display panel;a plurality of second sensing data lines connected to the second sensing units, the second sensing data lines extending in the vertical direction on the second display panel;a plurality of first sensing signal output units formed on the second display panel, the first sensing signal output units converting sensing data signals output from the first sensing data lines; anda plurality of second sensing signal output units formed on the second display panel, the second sensing signal output units converting sensing data signals output from the second sensing data lines,wherein the plurality of first sensing signal output units are formed at the left or right side of the second display panel.

11. The liquid crystal display of claim 10, further comprising a plurality of output data lines connected to the plurality of first sensing signal output units.

12. The liquid crystal display of claim 11, wherein the plurality of first sensing signal output units are vertically disposed in line.

13. The liquid crystal display of claim 12, wherein the plurality of output data lines extend in the vertical direction.

14. The liquid crystal display of claim 12, wherein the plurality of output data lines extend between the respective adjacent pixels in the horizontal direction in different lengths and then extend in the vertical direction.

15. The liquid crystal display of claim 12, wherein the adjacent first sensing signal output units are vertically disposed in a horizontally shifted manner at predetermined intervals.

16. The liquid crystal display of claim 15, wherein the plurality of output data lines extend in the vertical direction.

17. The liquid crystal display of any one of claims 10 to 16, wherein the sensing units each include a variable capacitor of which capacitance is changed depending on pressure and a reference capacitor connected to the sensing data line and the second voltage.