DISPLAY DEVICE HAVING TOUCH SENSOR

• US 20170115808A1
• Filed: 10/17/2016
• Published: 04/27/2017
• Est. Priority Date: 10/27/2015
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: CHO, Seungwan, SO, Byeongseong
• Granted Patent: US 10,216,319 B2
• Time in Patent Office: Days
• CPC Class Codes: G06F 2203/04108 Touchless 2D- digitiser, i.e. digitiser detecting the X/Y position of the input means, finger or stylus, also when it does not touch, but is proximate to the digitiser's interaction surface without distance measurement in the Z direction
• 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 3/04184 Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally
• CPC Class Codes: G06F 3/044 by capacitive means
• CPC Class Codes: G09G 2300/043 Compensation electrodes or other additional electrodes in matrix displays related to distortions or compensation signals, e.g. for modifying TFT threshold voltage in column driver
• CPC Class Codes: G09G 2300/0819 used for counteracting undesired variations, e.g. feedback or autozeroing
• CPC Class Codes: G09G 2310/0286 Details of a shift registers arranged for use in a driving circuit
• CPC Class Codes: G09G 3/3677 suitable for active matrices only

Abstract

A display device includes a display panel including a display driving circuit, and a touch sensing circuit. The display panel includes first and second panel blocks, each including pixel arrays including touch sensors. The display driving circuit includes a shift register for sequentially outputting a gate pulse applied to a gate line. The shift register includes first and second shift registers and a compensation stage. The first shift register applies a gate pulse to gate lines arranged in the first panel block, and the second shift register applies a gate pulse to gate lines arranged in the second panel block during at least a portion of the display period when a node of the second shift register is charged to a predetermined level. The compensation stage charges the node of the second shift register upon receiving a bridge clock during a touch sensing period of the first panel block.

Claims

1. A display device comprising:

a display panel including first and second panel blocks each including pixel arrays including touch sensors;

a display driving circuit writing image data to pixels of the first panel block during a first display period and writing image data to pixels of the second panel block during a second display period; and

a touch sensing circuit driving the touch sensors of the first panel block during a first touch sensing period and driving the touch sensors of the second panel block during a second touch sensing period,

wherein the display driving circuit comprises;

a shift register sequentially outputting a gate pulse applied to a gate line, the shift register comprising;

a first shift register applying a gate pulse to first gate lines arranged in the first panel block;

a second shift register applying a gate pulse to second gate lines arranged in the second panel block, the second shift register applying the gate pulse to a gate line of the second gate lines during at least a portion of the second display period when a node of the second shift register is charged to a predetermined level; and

a compensation circuit stage receiving a bridge clock and charging the node of the second shift register responsive to the bridge clock during the first touch sensing period of the first panel block.

2. The display device of claim 1,

wherein the first shift register includes first to Kth stages outputting K number of gate pulses, and the second shift register includes (K+1)th to 2Kth stages,

where K is a natural number,

wherein each of the first to 2Kth stages comprise:

a pull-up transistor including a gate electrode connected to a node, a drain electrode connected to a gate clock input terminal, and a source electrode connected to a gate pulse output terminal; and

a start signal transistor including a gate electrode connected to a start signal input terminal, a drain electrode connected to a high potential voltage input terminal, and a source electrode connected to the node, and

wherein the compensation circuit stage charges a node of the (K+1)th stage of the second shift register after a gate pulse is output from the Kth stage of the first shift register.

3. The display device of claim 2, wherein the compensation circuit stage includes a compensation transistor including a gate electrode connected to a node of the Kth stage of the first shift register, a source electrode connected to a start control transistor of the (K+1)th stage of the second shift register, and a drain electrode receiving the bridge clock.

4. The display device of claim 3,

wherein a start control transistor of the Kth stage of the first shift register charges the node of the Kth stage of the first shift register in response to a gate pulse output by a (K−

1) th stage of the first shift register, and

wherein the compensation transistor is turned on when the node of the Kth stage of the first shift register is charged, to output the bridge clock as a compensation start signal.

5. The display device of claim 4, wherein the bridge clock bootstraps the node of the Kth stage of the first shift register during the touch sensing period to cause the compensation transistor to output the compensation start signal during the touch sensing period.

6. The display device of claim 5, wherein the bridge clock is applied as an alternating current (AC) waveform to the compensation transistor during the touch sensing period, the compensation transistor outputs the compensation start signal for AC-driving the start control transistor of the (K+1)th stage of the second shift register during the touch sensing period.

7. The display device of claim 2, wherein the compensation circuit stage comprises:

a first transistor including a gate electrode connected to a gate pulse output terminal of the Kth stage of the first shift register, a drain electrode connected to a high potential voltage input terminal, and a source electrode connected to a bridge node; and

a second transistor including a gate electrode connected to the bridge node, a drain electrode connected to a bridge clock input terminal, and a source electrode connected to a start control transistor of the (K+1)th stage of the second shift register.

8. The display device of claim 7, wherein the first transistor charges the bridge node in response to the gate pulse output by the Kth stage of the first shift register.

9. The display device of claim 8, wherein the bridge clock bootstraps the bridge node during the touch sensing period to cause the second transistor to output the compensation start signal during the touch sensing period.

10. A touch sensitive display device, comprising:

a display panel driven in a first display period, a second display period, and a touch sensing period between the first display period and the second display period, the display panel including a first plurality of gate lines and a second plurality of gate lines; and

a shift register to drive the first plurality of gate lines and the second plurality of gate lines, the shift register comprising;

a first shift register to sequentially apply a gate pulse to the plurality of first gate lines of the display panel during the first display period;

a second shift register to sequentially apply a gate pulse to the plurality of second gates lines of the display panel during the second display period, the second shift register applying the gate pulse to a gate line of the second gate lines responsive to a node of the second shift register being charged to a predetermined level; and

a compensation circuit to charge the node of the second shift register during the touch sensing period between the first display period and the second display period and in response to a signal from the first shift register.

11. The touch sensitive display device of claim 10, wherein the compensation circuit maintains a voltage of the node of the second shift register during the touch sensing period.

12. The touch sensitive display device of claim 10,

wherein the first shift register includes first to Kth stages, the second shift register includes (K+1)th to 2Kth stages, where K is a natural number, and

wherein each of the first to 2Kth stages comprise:

a pull-up transistor including a gate electrode connected to a node, an electrode connected to a gate clock input terminal, and an electrode connected to a gate pulse output terminal; and

a start control transistor including a gate electrode connected to a start signal input terminal, an electrode connected to a high potential voltage input terminal, and an electrode connected to the node.

13. The touch sensitive display device of claim 12, wherein the compensation circuit charges the node of the second shift register in response to a signal from the first shift register by charging the node of the (K+1)th stage of the second shift register responsive to a charge at the node of the Kth stage of the first shift register.

14. The touch sensitive display device of claim 13, wherein the compensation circuit comprises a compensation transistor including a gate electrode connected to a the node of the Kth stage of the first shift register, an electrode receiving a clock signal, and an electrode connected to the start control transistor of the (K+1)th stage of the second shift register.

15. The touch sensitive display device of claim 12, wherein the compensation circuit charges the node of the second shift register in response to a signal from the first shift register by charging the node of the (K+1)th stage of the second shift register responsive to the gate pulse output from the Kth stage of the first shift register.

16. The touch sensitive display device of claim 15, wherein the compensation circuit comprises:

a first transistor including a gate electrode connected to the gate pulse output terminal of the Kth stage of the first shift register, an electrode connected to a high potential voltage input terminal, and an electrode connected to a bridge node; and

a second transistor including a gate electrode connected to the bridge node, an electrode receiving a clock signal, and an electrode connected to the start control transistor of the (K+1)th stage of the second shift register.

17. The touch sensitive display device of claim 10, wherein the compensation circuit charges the node further based on a clock signal.

18. The touch sensitive display device of claim 11, wherein the clock signal is an alternating current (AC) waveform during the touch sensing period.

19. The touch sensitive display device of claim 11, wherein the clock signal has a first DC voltage level during the first display period and the second display period, and has a second DC voltage level during the touch sensing period.