METHOD FOR DRIVING PIXEL CIRCUIT

• US 20180240400A1
• Filed: 04/23/2018
• Published: 08/23/2018
• Est. Priority Date: 11/21/2017
• Status: Active Grant

• Current Assignee: Shanghai Tianma Micro-Electronics Company Limited (Tianma Microelectronics Company Limited)
• Original Assignee: Shanghai Tianma Micro-Electronics Company Limited (Tianma Microelectronics Company Limited)
• Inventors: ZHOU, Xingyao, LI, Yuan
• Granted Patent: US 10,699,640 B2
• Time in Patent Office: Days
• 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 2310/0262 The addressing of the pixel, in a display other than an active matrix LCD, involving the control of two or more scan electrodes or two or more data electrodes, e.g. pixel voltage dependent on signals of two data electrodes
• CPC Class Codes: G09G 2310/08 Details of timing specific for flat panels, other than clock recovery
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0257 Reduction of after-image effects
• CPC Class Codes: G09G 2320/045 Compensation of drifts in the characteristics of light emitting or modulating elements
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: G09G 3/325 the data current flowing through the driving transistor during a setting phase, e.g. by using a switch for connecting the driving transistor to the data driver

Abstract

A method for driving a pixel circuit is disclosed. The method includes: a time for displaying a frame including N initialization phases and N data signal voltage writing phases before a light-emitting phase. The ith of the N data signal voltage writing phases is after the ith of the N initialization phases and before the (i+1)th of the N initialization phases, and the Nth data signal voltage writing phase is after the Nth initialization phase, 1≤i≤N−1, i is an integer and N is an integer greater than 1. In the initialization phase, an initialization voltage is applied to the gate electrode of the driving transistor by the initialization module. In the data signal voltage writing phase, a data signal voltage is applied to the gate electrode of the driving transistor by the data signal voltage writing module.

Claims

1. A method for driving a pixel circuit, wherein the pixel circuit comprises a light-emitting element, a driving transistor, an initialization module, a data signal voltage writing module, a storage module for maintaining a voltage of a gate electrode of the driving transistor, and a time for displaying a frame, wherein the time for displaying the frame comprises:

a light-emitting phase, N initialization phases, and N data signal voltage writing phases before the light-emitting phase, wherein the ith of the N data signal voltage writing phases is after the ith of the N initialization phase and before the (i+1)th of the N initialization phases, and wherein the Nth data signal voltage writing phase is after the Nth initialization phase, 1≤

i≤

N−

1, i is an integer and N is an integer greater than 1;

the method comprises;

applying an initialization voltage to the gate electrode of the driving transistor by the initialization module in each of the N initialization phases;

applying a data signal voltage to the gate electrode of the driving transistor by the data signal voltage writing module in each of the N data signal voltage writing phases; and

generating a driving current for driving the light-emitting element to emit light by the driving transistor in the light-emitting phase.

2. The method for driving a pixel circuit according to claim 1, wherein the pixel circuit further comprises a first light-emitting control module configured to control the light-emitting element to emit light, and wherein the method further comprises turning off the first light-emitting control module in the N initialization phases and N data signal voltage writing phases.

3. The method for driving a pixel circuit according to claim 1, wherein N is set to be 3.

4. The method for driving a pixel circuit according to claim 1, wherein the applying a data signal voltage to the gate electrode of the driving transistor by the data signal voltage writing module in each of the N data signal voltage writing phases comprises:

in each of the first to the (N−

1)th data signal voltage writing phases, applying a data signal voltage corresponding to a maximum brightness to the gate electrode of the driving transistor by the data signal voltage writing module, and

in the Nth data signal voltage writing phase, applying a data signal voltage corresponding to a greyscale to be displayed by the data signal voltage writing module.

5. The method for driving a pixel circuit according to claim 1, wherein every two adjacent initialization phases in the N initialization phases are spaced apart by a first time interval, and every two adjacent data signal voltage writing phases in the N data signal voltage writing phases are spaced apart by a second time interval.

6. The method for driving a pixel circuit according to claim 2, wherein a control terminal of the initialization module is electrically connected to a first scanning line, a control terminal of the data signal voltage writing module is electrically connected to a second scanning line, a control terminal of the first light-emitting control module is electrically connected to a first light-emitting signal line;

wherein each of the first scanning line and the second scanning line comprises N scanning signal pulses; and

wherein the first light-emitting signal line comprises at least one scanning signal pulse, wherein the at least one scanning signal pulse of the first light-emitting signal line covers the N scanning signal pulses of the first scanning line and the N scanning signal pulses of the second scanning line.

7. The method for driving a pixel circuit according to claim 2, wherein the light-emitting phase comprises at least one light-emitting sub-phase and at least one turn-off phase, and wherein the method further comprises:

in each of the at least one light-emitting sub-phase, turning on the first light-emitting control module;

in each of the at least one turn-off phase, turning off the first light-emitting control module.

8. The method for driving a pixel circuit according to claim 2, wherein the pixel circuit further comprises a threshold compensation module, the threshold compensation module comprises a second transistor, the data signal voltage writing module comprises a third transistor, the first light-emitting control module comprises a fourth transistor and a fifth transistor, the initialization module comprises a sixth transistor, and the storage module comprises a first capacitor;

a first electrode of the fourth transistor is electrically connected to a first power voltage signal line, a second electrode of the fourth transistor is electrically connected to a first electrode of the driving transistor, and a gate electrode of the fourth transistor is electrically connected to a first light-emitting signal line;

a first electrode of the fifth transistor is electrically connected to a second electrode of the driving transistor, a second electrode of the fifth transistor is electrically connected to a first electrode of the light-emitting element, and a gate electrode of the fifth transistor is electrically connected to the first light-emitting signal line;

a first electrode of the sixth transistor is electrically connected to an initialization voltage signal line, a second electrode of the sixth transistor is electrically connected to the gate electrode of the driving transistor, and a gate electrode of the sixth transistor is electrically connected to a first scanning line;

a first electrode of the second transistor is electrically connected to the second electrode of the driving transistor, a second electrode of the second transistor is electrically connected to the gate electrode of the driving transistor, and a gate electrode of the second transistor is electrically connected to a second scanning line;

a first electrode of the third transistor is electrically connected to a data line, a second electrode of the third transistor is electrically connected to the first electrode of the driving transistor , and a gate electrode of the third transistor is electrically connected to the second scanning line;

a first electrode of the first capacitor is electrically connected to the gate electrode of the driving transistor, and a second electrode of the first capacitor is electrically connected to the first power voltage signal line; and

a second electrode of the light-emitting element is electrically connected to a second power voltage signal line.

9. The method for driving a pixel circuit according to claim 2, wherein the pixel circuit further comprises a threshold compensation module and a second light-emitting control module, the threshold compensation module comprises a second transistor, the data signal voltage writing module comprises a third transistor, the first light-emitting control module comprises a fourth transistor, the second light-emitting control module comprises a fifth transistor, the initialization module comprises a sixth transistor, and the storage module comprises a first capacitor;

a first electrode of the driving transistor is electrically connected to a first power voltage signal line, and a first electrode of the first capacitor is electrically connected to the gate electrode of the driving transistor;

a first electrode of the sixth transistor is electrically connected to an initialization voltage signal line, a second electrode of the sixth transistor is electrically connected to the gate electrode of the driving transistor, and a gate electrode of the sixth transistor is electrically connected to a first scanning line;

a first electrode of the second transistor is electrically connected to a second electrode of the driving transistor, a second electrode of the second transistor is electrically connected to the gate electrode of the driving transistor, and a gate electrode of the second transistor is electrically connected to a second scanning line;

a first electrode of the third transistor is electrically connected to a data line, a second electrode of the third transistor is electrically connected to a second electrode of the first capacitor, and a gate electrode of the third transistor is electrically connected to the second scanning line;

a first electrode of the fourth transistor is electrically connected to one of the first power voltage signal line and a first reference voltage signal line, a second electrode of the fourth transistor is electrically connected to a second electrode of the first capacitor, and a gate electrode of the fourth transistor is electrically connected to a first light-emitting signal line;

a first electrode of the fifth transistor is electrically connected to the second electrode of the driving transistor, a second electrode of the fifth transistor is electrically connected to a first electrode of the light-emitting element, and a gate electrode of the fifth transistor is electrically connected to a second light-emitting line; and

a second electrode of the light-emitting element is electrically connected to a second power voltage signal line.

10. The method for driving a pixel circuit according to claim 2, wherein the pixel circuit further comprises a threshold compensation module and a second light-emitting control module, the threshold compensation module comprises a second transistor, the data signal voltage writing module comprises a third transistor, the first light-emitting control module comprises a fourth transistor, the second light-emitting control module comprises a fifth transistor, the initialization module comprises a sixth transistor, and the storage module comprises a first capacitor;

a first electrode of the sixth transistor is electrically connected to an initialization voltage signal line, a second electrode of the sixth transistor is electrically connected to a first electrode of the light-emitting element, and a gate electrode of the sixth transistor is electrically connected to a first scanning line;

a first electrode of the third transistor is electrically connected to a data line, a second electrode of the third transistor is electrically connected to a first electrode of the driving transistor, and a gate electrode of the third transistor is electrically connected to a second scanning line;

a first electrode of the second transistor is electrically connected to a second electrode of the driving transistor, a second electrode of the second transistor is electrically connected to the gate electrode of the driving transistor, and a gate electrode of the second transistor is electrically connected to the second scanning line;

a first electrode of the fourth transistor is electrically connected to a first power voltage signal line, a second electrode of the fourth transistor is electrically connected to the first electrode of the driving transistor, and a gate electrode of the fourth transistor is electrically connected to a first light-emitting control line;

a first electrode of the fifth transistor is electrically connected to the second electrode of the driving transistor, a second electrode of the fifth transistor is electrically connected to the first electrode of the light-emitting element, and a gate electrode of the fifth transistor is electrically connected to a second light-emitting control line;

a first electrode of the first capacitor is electrically connected to the gate electrode of the driving transistor, and a second electrode of the first capacitor is electrically connected to the first power voltage signal line; and

a second electrode of the light-emitting element is electrically connected to a second power voltage signal line.

11. The method for driving a pixel circuit according to claim 8, wherein the pixel circuit further comprises a reset module, the reset module comprises a seventh transistor, a gate electrode of the seventh transistor is electrically connected to the first scanning line, a first electrode of the seventh transistor is electrically connected to the initialization voltage line, and a second electrode of the seventh transistor is electrically connected to the first electrode of the light-emitting element.

12. The method for driving a pixel circuit according to claim 9, wherein the pixel circuit further comprises a reset module, the reset module comprises a seventh transistor, a gate electrode of the seventh transistor is electrically connected to the first scanning line, a first electrode of the seventh transistor is electrically connected to the initialization voltage line, and a second electrode of the seventh transistor is electrically connected to the first electrode of the light-emitting element.

13. The method for driving a pixel circuit according to claim 6, wherein for two adjacent rows of pixel circuits, the second scanning line electrically connected to a preceding one of the two adjacent rows of pixel circuits is reused as the first scanning line electrically connected to a subsequent one of the two adjacent rows of pixel circuits.