OLED-Based Display Device Including a Pixel Circuit, and Driving Methods Thereof

• US 20130249875A1
• Filed: 01/29/2013
• Published: 09/26/2013
• Est. Priority Date: 03/21/2012
• Status: Active Grant

• Current Assignee: Innocom Technology Limited, InnoLux Corporation
• Original Assignee: Innocom Technology Limited, InnoLux Corporation
• Inventors: TSENG, Ming-Chun, CHEN, Lien-Hsiang, GUO, Gong-Chen
• Granted Patent: US 9,202,415 B2
• Time in Patent Office: Days
• US Class Current: 345/205
• CPC Class Codes: G09G 2300/0819 used for counteracting undesired variations, e.g. feedback or autozeroing
• CPC Class Codes: G09G 2300/0852 being a dynamic memory with more than 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 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: G09G 3/3266 Details of drivers for scan electrodes

Abstract

An organic light emitting diode (OLED) based display device including a pixel circuit that includes: an OLED to be connected to a first power terminal, a transistor connected to the OLED, a first capacitor connected to the transistor, a second capacitor connected to the first capacitor and the transistor, a first switch receiving a data signal and a scanning signal and connected to the first capacitor, a second switch connected to the transistor and receiving an enable signal, a third switch connected to the transistor and receiving a compensation signal, and a switching unit configured to transmit one of the enable signal, voltage at a terminal of the first capacitor, a reference signal and the scanning signal to a terminal of the transistor when operated in a conductive state.

Claims

1. An organic liquid emitting diode (OLED) based display device comprising a pixel circuit that includes:

an organic light emitting diode (OLED) having an anode and a cathode to be connected electrically to a first power terminal;

a transistor having a first terminal, a second terminal that is connected electrically to said anode of said OLED, and a control terminal;

a first capacitor having a first terminal and a second terminal that is connected electrically to said control terminal of said transistor;

a second capacitor having a first terminal that is connected electrically to said first terminal of said first capacitor, and a second terminal that is connected electrically to said second terminal of said transistor;

a first switch having a first terminal that is disposed to receive a data signal, a second terminal that is connected electrically to said first terminal of said first capacitor, and a control terminal that is disposed to receive a scanning signal, said first switch being operable to switch between a conductive state and a non-conductive state according to the scanning signal received by said first switch;

a second switch having a first terminal that is to be connected electrically to a second power terminal, a second terminal that is connected electrically to said first terminal of said transistor, and a control terminal that is disposed to receive an enable signal, said second switch being operable to switch between a conductive state and a non-conductive state according to the enable signal received by said second switch;

a third switch having a first terminal that is connected electrically to said first terminal of said transistor, a second terminal that is connected electrically to said control terminal of said transistor, and a control terminal that is disposed to receive a compensation signal, said third switch being operable to switch between a conductive state and a non-conductive state according to the compensation signal received by said third switch; and

a switching unit connected electrically to said second terminal of said transistor, disposed to receive the compensation signal, and operable to switch between a conductive state and a non-conductive state according to the compensation signal received by said switching unit;

wherein said switching unit is configured to transmit one of the enable signal, voltage at said first terminal of said first capacitor, a reference signal and the scanning signal to said second terminal of said transistor when said switching unit is operated in the conductive state.

2. The OLED-based display device as claimed in claim 1, wherein said switching unit includes a fourth switch having a first terminal that is disposed to receive the enable signal, a second terminal that is connected electrically to said second terminal of said transistor, and a control terminal that is disposed to receive the compensation signal,

said fourth switch permitting transmission of the enable signal therethrough to said second terminal of said transistor when said switching unit is operated in the conductive state, and preventing transmission of the enable signal therethrough to said second terminal of said transistor when said switching unit is operated in the non-conductive state.

3. The OLED-based display device as claimed in claim 2, wherein said switching unit further includes a fifth switch having a first terminal, a second terminal that is connected electrically to said first terminal of said first capacitor, and a control terminal that is disposed to receive the compensation signal, said first terminal of said fifth switch being disposed to receive one of the enable signal, a voltage at said second terminal of said transistor, the reference signal and the scanning signal,

said fifth switch permitting transmission of said one of the enable signal, the voltage at said second terminal of said transistor, the reference signal and the scanning signal therethrough to said first terminal of said first capacitor when said switching unit is operated in the conductive state, and preventing transmission of said one of the enable signal, the voltage at said second terminal of said transistor, the reference signal and the scanning signal therethrough to said first terminal of said first capacitor when said switching unit is operated in the non-conductive state.

4. The OLED-based display device as claimed in claim 1, wherein said switching unit includes a fourth switch having a first terminal that is connected electrically to said first terminal of said first capacitor, a second terminal that is connected electrically to said second terminal of said transistor, and a control terminal that is disposed to receive the compensation signal,

said fourth switch permitting transmission of the voltage at said first terminal of said first capacitor therethrough to said second terminal of said transistor when said switching unit is operated in the conductive state, and preventing transmission of the voltage at said first terminal of said first capacitor therethrough to said second terminal of said transistor when said switching unit is operated in the non-conductive state.

5. The OLED-based display device as claimed in claim 4, wherein said switching unit further includes a fifth switch having a first terminal, a second terminal that is connected electrically to said first terminal of said first capacitor, and a control terminal that is disposed to receive the compensation signal, said first terminal of said fifth switch being disposed to receive one of the enable signal, the reference signal and the scanning signal,

said fifth switch permitting transmission of said one of the enable signal, the reference signal and the scanning signal therethrough to said first terminal of said first capacitor when said switching unit is operated in the conductive state, and preventing transmission of said one of the enable signal, the reference signal and the scanning signal therethrough to said first terminal of said first capacitor when said switching unit is operated in the non-conductive state.

6. The OLED-based display device as claimed in claim 1, wherein said switching unit includes a fourth switch having a first terminal that is disposed to receive the reference signal, a second terminal that is connected electrically to said second terminal of said transistor, and a control terminal that is disposed to receive the compensation signal,

said fourth switch permitting transmission of the reference signal therethrough to said second terminal of said transistor when said switching unit is operated in the conductive state, and preventing transmission of the reference signal therethrough to said second terminal of said transistor when said switching unit is operated in the non-conductive state.

7. The OLED-based display device as claimed in claim 6, wherein said switching unit further includes a fifth switch having a first terminal, a second terminal that is connected electrically to said first terminal of said first capacitor, and a control terminal that is disposed to receive the compensation signal, said first terminal of said fifth switch being disposed to receive one of the enable signal, a voltage at said second terminal of said transistor, the reference signal and the scanning signal,

said fifth switch permitting transmission of said one of the enable signal, the voltage at said second terminal of said transistor, the reference signal and the scanning signal therethrough to said first terminal of said first capacitor when said switching unit is operated in the conductive state, and preventing transmission of said one of the enable signal, the voltage at said second terminal of said transistor, the reference signal and the scanning signal therethrough to said first terminal of said first capacitor when said switching unit is operated in the non-conductive state.

8. The OLED-based display device as claimed in claim 1, wherein said switching unit includes a fourth switch having a first terminal that is disposed to receive the scanning signal, a second terminal that is connected electrically to said second terminal of said transistor, and a control terminal that is disposed to receive the compensation signal,

said fourth switch permitting transmission of the scanning signal therethrough to said second terminal of said transistor when said switching unit is operated in the conductive state, and preventing transmission of the scanning signal therethrough to said second terminal of said transistor when said switching unit is operated in the non-conductive state.

9. The OLED-based display device as claimed in claim 8, wherein said switching unit further includes a fifth switch having a first terminal, a second terminal that is connected electrically to said first terminal of said first capacitor, and a control terminal that is disposed to receive the compensation signal, said first terminal of said fifth switch being disposed to receive one of the enable signal, a voltage at said second terminal of said transistor, the reference signal and the scanning signal,

said fifth switch permitting transmission of said one of the enable signal, the voltage at said second terminal of said transistor, the reference signal and the scanning signal therethrough to said first terminal of said first capacitor when said switching unit is operated in the conductive state, and preventing transmission of said one of the enable signal, the voltage at said second terminal of said transistor, the reference signal and the scanning signal therethrough to said first terminal of said first capacitor when said switching unit is operated in the non-conductive state.

10. A driving method for driving a pixel circuit of an organic light emitting diode based display device according to any one of claims 2, 4 and 6, the driving method comprising:

(A) applying the data signal, the scanning signal, the enable signal, and the compensation signal to the pixel circuit such that the OLED is in the non-conductive state, the transistor is in the non-conductive state, the first switch is in the conductive state, the second switch is in the conductive state, the third switch is in the non-conductive state, and the switching unit is in the non-conductive state;

(B) applying the data signal, the scanning signal, the enable signal, and the compensation signal to the pixel circuit such that the OLED is in the non-conductive state, the transistor switches from the conductive state to the non-conductive state, the first switch is in the conductive state, the second switch is in the non-conductive state, the third switch is in the conductive state, and the switching unit is in the conductive state;

(C) applying the data signal, the scanning signal, the enable signal, and the compensation signal to the pixel circuit such that the OLED is in the non-conductive state, the transistor is in the conductive state, the first switch is in the conductive state, the second switch is in the non-conductive state, the third switch is in the non-conductive state, and the switching unit is in the non-conductive state; and

(D) applying the scanning signal, the enable signal, and the compensation signal to the pixel circuit such that the OLED is in the conductive state, the transistor is in the conductive state, the first switch is in the non-conductive state, the second switch is in the conductive state, the third switch is in the non-conductive state, and the switching unit is in the non-conductive state.

11. A driving method for driving a pixel circuit of an organic light emitting diode based display device according to any one of claims 3, 5, 7, and 9, the driving method comprising:

(A) applying the data signal, the scanning signal, the enable signal, and the compensation signal to the pixel circuit such that the OLED is in the non-conductive state, the transistor is in the non-conductive state, the first switch is in the conductive state, the second switch is in the conductive state, the third switch is in the non-conductive state, and the switching unit is in the non-conductive state;

(B) applying the scanning signal, the enable signal, and the compensation signal to the pixel circuit such that the OLED is in the non-conductive state, the transistor switches from the conductive state to the non-conductive state, the first switch is in the non-conductive state, the second switch is in the non-conductive state, the third switch is in the conductive state, and the switching unit is in the conductive state;

(C) applying the data signal, the scanning signal, the enable signal, and the compensation signal to the pixel circuit such that the OLED is in the non-conductive state, the transistor is in the conductive state, the first switch is in the conductive state, the second switch is in the non-conductive state, the third switch is in the non-conductive state, and the switching unit is in the non-conductive state; and

(D) applying the scanning signal, the enable signal, and the compensation signal to the pixel circuit such that the OLED is in the conductive state, the transistor is in the conductive state, the first switch is in the non-conductive state, the second switch is in the conductive state, the third switch is in the non-conductive state, and the switching unit is in the non-conductive state.