Pixel circuit for organic light emitting diode, driving method for pixel circuit and active matrix organic light emitting diode display device

• US 9,466,242 B2
• Filed: 07/05/2013
• Issued: 10/11/2016
• Est. Priority Date: 04/15/2013
• Status: Active Grant

• Current Assignee: BOE Technology Group Co., Ltd., Chengdu BOE Optoelectronics Technology Company Limited (BOE Technology Group Co., Ltd.)
• Original Assignee: BOE Technology Group Co., Ltd., Chengdu BOE Optoelectronics Technology Company Limited (BOE Technology Group Co., Ltd.)
• Inventors: Qing, Haigang, Qi, Xiaojing
• Primary Examiner(s): Snyder, Adam J
• Application Number:
  US14/368,863
• Publication Number:
  US 20150221255A1
• Time in Patent Office: 1,194 Days
• Field of Search: 345 76- 81, 345173-178, 315/169.3, 178 1801- 1811
• US Class Current: 1/1
• 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 2300/0819 used for counteracting undesired variations, e.g. feedback or autozeroing
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2300/0861 with additional control of the display period without amending the charge stored in a pixel memory, e.g. by means of additional select electrodes
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: G09G 3/3258 with pixel circuitry controlling the voltage across the light-emitting element

Abstract

A pixel circuit, a driving method for driving the pixel circuit and a display device comprising the pixel circuit. The pixel circuit insulates the electric connection between the drain of the driving transistor and the organic light-emitting diode by the insulating transistor when the data is written into the storage capacitor, and the threshold voltage of the driving transistor and the data voltage signal are pre-stored by the storage capacitor, which can compensate the shift in the threshold voltage effectively and in turn can ensure the uniformity and stabilization of the driving current. Additionally, the touch control circuit in the embodiments of the present disclosure multiplexes the scan signal of the pixel circuit, and the coupling capacitor in the touch control circuit is charged through the charging transistor while the storage capacitor is charged, therefore an integration of the touch control circuit into the pixel circuit is achieved perfectly.

Claims

1. A pixel circuit comprising an electroluminescent device, a driving transistor, a first switching unit, a compensating unit, an insulating unit, a storage capacitor, and a touch control circuit;

the first switching unit is configured to control writing of a data voltage on a data line, a first terminal of the first switching unit is connected with a first terminal of the storage capacitor, and a second terminal thereof is connected with the data line;

a second terminal of the storage capacitor is connected with a gate of the driving transistor and a first terminal of the compensating unit;

the compensating unit is configured to pre-store a threshold voltage of the driving transistor into the storage capacitor, and a second terminal of the compensating unit is connected with a drain of the driving transistor;

a source of the driving transistor is connected with a power supply terminal, and the drain thereof is connected with a first terminal of the insulation unit;

the insulating unit is configured to insulate an electric connection between the driving transistor and the electroluminescent device, and a second terminal of the insulating unit is connected with a first terminal of the electroluminescent device; and

a second terminal of the electroluminescent device is connected with a ground terminal;

the touch control circuit comprises a charging transistor, a coupling capacitor, a sensing electrode, an amplifying transistor, a third switching transistor, a second scan signal terminal and a sensing line;

a gate of the charging transistor is connected with a third control signal terminal, a source thereof is connected with the second terminal of the storage capacitor, and a drain thereof is connected with a first terminal of the coupling capacitor, the sensing electrode and a gate of the amplifying transistor;

a second terminal of the coupling capacitor is connected with a first control signal terminal;

a source of the amplifying transistor is connected with the power supply terminal, and a drain thereof is connected with a source of the third switching transistor; and

a gate of the third switching transistor is connected with the second scan signal terminal, and a drain thereof is connected with the sensing line.

2. The pixel circuit of claim 1, wherein the electroluminescent device is an Organic Light-Emitting Diode, the first switching unit is a first switching transistor, the compensating unit is a compensating transistor, and the insulating unit is an insulating transistor;

a gate of the first switching transistor is connected with a first scan signal terminal, a source thereof is connected with the first terminal of the storage capacitor, and a drain thereof is connected with the data line;

the second terminal of the storage capacitor is connected with the gate of the driving transistor and a drain of the compensating transistor;

a gate of the compensating transistor is connected with the first scan signal terminal, and a source thereof is connected with the drain of the driving transistor;

the source of the driving transistor is connected with the power supply terminal, and the drain thereof is connected with a source of the insulating transistor;

a gate of the insulating transistor is connected with a second control signal terminal, and a drain thereof is connected with an anode of the organic light-emitting diode; and

a cathode of the organic light-emitting diode is connected with the ground terminal.

3. The pixel circuit of claim 2, further comprising a second switching transistor;

a gate of the second switching transistor is connected with the first control signal terminal, a source thereof is connected with the first terminal of the storage capacitor, and a drain thereof is connected with a reference voltage terminal.

4. The pixel circuit of claim 2, wherein the third control signal terminal is the first scan signal terminal.

5. A driving method for the pixel circuit of claim 4, comprising steps of:

S1, applying a scan signal at the first scan signal terminal to turn on the first switching transistor, the compensating transistor and the charging transistor, applying control signals at the first control signal terminal and the second control signal terminal to turn off the second switching transistor and the insulating transistor, so that a threshold voltage of the driving transistor and the data voltage on the data line are written into the storage capacitor, and charging, by the power supply terminal, the coupling capacitor through the driving transistor and the charging transistor; and

S2, applying a scan signal at the first scan signal terminal to turn off the first switching transistor, the compensating transistor and the charging transistor, applying control signals at the first control signal terminal and the second control signal terminal to turn on the second switching transistor and the insulating transistor, driving the organic light-emitting diode to emit light by using the voltages stored in the storage capacitor, applying a scan signal at the second scan signal terminal to turn on the third switching transistor, and monitoring changes in a current on the sensing line.

6. The driving method for the pixel circuit of claim 5, wherein the pixel circuit further comprises a second switching transistor;

a gate of the second switching transistor is connected with the first control signal terminal, a source thereof is connected with the first terminal of the storage capacitor, and a drain thereof is connected with a reference voltage terminal, before the step S1, the driving method further comprises;

applying a scan signal at the first scan signal terminal and applying a control signal at the second control signal terminal to turn on the first switching transistor, the compensating transistor, the insulating transistor and the charging transistor, applying a control signal at the first control signal terminal and applying a scan signal at the second scan signal terminal to turn off the second switching transistor and the third switching transistor, and resetting the storage capacitor and the coupling capacitor.

7. The pixel circuit of claim 2, wherein each of the transistors has a same channel type.

8. A display device comprising the pixel circuit of claim 1.

9. The display device of claim 8, wherein the electroluminescent device is an Organic Light-Emitting Diode, the first switching unit is a first switching transistor, the compensating unit is a compensating transistor, and the insulating unit is an insulating transistor;

a gate of the first switching transistor is connected with a first scan signal terminal, a source thereof is connected with the first terminal of the storage capacitor, and a drain thereof is connected with the data line;

the second terminal of the storage capacitor is connected with the gate of the driving transistor and a drain of the compensating transistor;

a gate of the compensating transistor is connected with the first scan signal terminal, and a source thereof is connected with the drain of the driving transistor;

the source of the driving transistor is connected with the power supply terminal, and the drain thereof is connected with a source of the insulating transistor;

a gate of the insulating transistor is connected with a second control signal terminal, and a drain thereof is connected with an anode of the organic light-emitting diode; and

a cathode of the organic light-emitting diode is connected with the ground terminal.

10. The display device of claim 9, further comprising a second switching transistor;

a gate of the second switching transistor is connected with the first control signal terminal, a source thereof is connected with the first terminal of the storage capacitor, and a drain thereof is connected with a reference voltage terminal.

11. The display device of claim 9, wherein the third control signal terminal is the first scan signal terminal.

12. The display device of claim 9, wherein each of the transistors has a same channel type.