Pixel circuit having a plurality of blue organic light-emitting diodes and driving method thereof

• US 9,536,474 B2
• Filed: 05/30/2014
• Issued: 01/03/2017
• Est. Priority Date: 09/03/2013
• Status: Active Grant

• Current Assignee: BOE Technology Group Co., Ltd.
• Original Assignee: BOE Technology Group Co., Ltd.
• Inventors: Ren, Lijun, Duan, Liye
• Primary Examiner(s): Pham, Long D
• Application Number:
  US14/408,485
• Publication Number:
  US 20150332628A1
• Time in Patent Office: 949 Days
• Field of Search: 345/82, 345/76
• US Class Current: 1/1
• CPC Class Codes: G09G 2300/0452 Details of colour pixel setup, e.g. pixel composed of a red, a blue and two green components
• CPC Class Codes: G09G 2300/0809 Several active elements per pixel in active matrix panels
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2310/08 Details of timing specific for flat panels, other than clock recovery
• CPC Class Codes: G09G 2320/0242 Compensation of deficiencies in the appearance of colours
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 2320/0666 for control of colour parameters, e.g. colour temperature
• CPC Class Codes: G09G 2330/08 Fault-tolerant or redundant circuits, or circuits in which repair of defects is prepared
• CPC Class Codes: G09G 3/2003 Display of colours specific for liquid crystal displays G09G3/3607
• 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

The present disclosure provides a pixel circuit, its driving method, an array substrate and a display device. The pixel circuit includes a plurality of pixels, each of which includes a blue sub-pixel and a driving module for driving the blue sub-pixel. The blue sub-pixel includes N blue OLEDs, and N is a positive integer greater than 1. The driving module is configured to drive the N blue OLEDs in a time division manner. According to the present disclosure, the blue sub-pixel is segmented into several portions, and merely a portion of the blue sub-pixel is displayed each time. As a result, it is able to prolong the service time of the blue sub-pixel, thereby to increase the service life of an AMOLED panel.

Claims

1. A pixel circuit, comprising a plurality of pixels, each of the plurality of pixels includes a blue sub-pixel and a driving module, wherein

the blue sub-pixel comprises N blue organic light-emitting diodes (OLEDs), and N is a positive integer greater than 1,

the driving module is configured to drive the N blue OLEDs in a time division manner,

wherein the driving module comprises a driver circuit for driving the blue sub-pixel in a time division manner, and the driver circuit includes an input transistor and N driving units,

a gate electrode of the input transistor is connected to a scanning line, a first electrode of the input transistor is connected to the N driving units, and a second electrode of the input transistor is connected to a data line,

a cathode of each of the N blue OLEDs is connected to a first level output end, and an anode thereof is connected to a level output and via the driving unit, and

the driving unit is configured to, when an absolute value of a voltage difference between a current level output end connected to the driving unit and the first level output end is greater than an absolute value of a turn-on voltage of the blue OLED connected to the driving unit and when the level output ends other than the current level output end and the first level output end are floating, drive the blue OLED to emit light.

2. The pixel circuit according to claim 1, wherein the pixel further comprises a red sub-pixel and a green sub-pixel, and the driving module is further configured to drive the red sub-pixel and the green sub-pixel while driving the N blue OLEDs in a time division manner.

3. The pixel circuit according to claim 1, wherein the driving unit comprises a storage capacitor and N driving transistors,

gate electrodes of the N driving transistors are connected to each other,

a second electrode of each driving transistor is connected to the level output end, and

the storage capacitor is connected between the gate electrode and the first electrode of the driving transistor.

4. A method for driving the pixel circuit according to claim 1, comprising:

segmenting a blue sub-pixel included in a pixel into N blue OLEDs, N being a positive integer greater than 1; and

driving, by a driving unit, the blue OLED to emit light when an absolute value of a voltage difference between a current level output end connected to the driving unit and a first level output end is greater than an absolute value of a turn-on voltage of the blue OLED connected to the driving unit and when the level output ends other than the current level output end and the first level output end are floating.

5. The method according to claim 4, wherein the driving module drives a red sub-pixel and a green sub-pixel of the pixel to which the blue sub-pixel belongs while driving the N blue OLEDs included in the pixel in a time division manner.

6. An array substrate comprising the pixel circuit according to claim 1.

7. A display device comprising the array substrate according to claim 6.

8. The array substrate according to claim 6, wherein the pixel further comprises a red sub-pixel and a green sub-pixel, and

the driving module is further configured to drive the red sub-pixel and the green sub-pixel while driving the N blue OLEDs in a time division manner.

9. The array substrate according to claim 6, wherein the driving unit comprises a storage capacitor and N driving transistors,

gate electrodes of the N driving transistors are connected to each other,

a second electrode of each driving transistor is connected to the level output end, and

the storage capacitor is connected between the gate electrode and the first electrode of the driving transistor.

10. A pixel circuit, comprising a plurality of pixels, each of the plurality of pixels includes a blue sub-pixel and a driving module, wherein:

the blue sub-pixel comprises N blue organic light-emitting diodes (OLEDs), and N is a positive integer greater than 1,

the driving module is configured to drive the N blue OLEDs in a time division manner,

the driving module comprises a driver circuit for driving the blue sub-pixel in a time division manner, the driver circuit comprises an input transistor, a driving transistor, and a storage capacitor,

a gate electrode of the input transistor is connected to a scanning line, a first electrode of the input transistor is connected to anodes of the N blue OLEDs via the storage capacitor, and a second electrode of the input transistor is connected to a data line,

a gate electrode of the driving transistor is connected to the first electrode of the input transistor, a first electrode of the driving transistor is connected to anodes of the N blue OLEDs, and a second electrode of the driving transistor is connected to a first level output end,

the anodes of the N blue OLEDs are connected to each other, and cathodes of the N blue OLEDs are connected to N level output ends, respectively, and

the driver circuit is configured to, when an absolute value of a voltage difference between the first level output end and one of the N level output ends is greater than an absolute value of a turn-on voltage of the blue OLED connected to the one of the N level output ends and when a voltage difference between the level output ends other than the one of the N level output ends and the first level output end is less than the absolute value of the turn-on voltage of the blue OLED, drive the blue OLED to emit light.

11. A method for driving the pixel circuit according to claim 10, comprising:

segmenting a blue sub-pixel included in a pixel into N blue OLEDs, N being a positive integer greater than 1; and

driving, by a driver circuit, the blue OLED to emit light when an absolute value of a voltage difference between the first level output end and one of the N level output ends is greater than an absolute value of a turn-on voltage of the blue OLED connected to the one of the N level output ends and when a voltage difference between the level output ends other than the one of the N level output ends and the first level output end is less than the absolute value of the turn-on voltage of the blue OLED.

12. The method according to claim 11, wherein the driving module drives a red sub-pixel and a green sub-pixel of the pixel to which the blue sub-pixel belongs while driving the N blue OLEDs included in the pixel in a time division manner.

13. An array substrate comprising the pixel circuit according to claim 10.

14. A display device comprising the array substrate according to claim 13.