Light emitting display and driving method thereof

• US 20050285825A1
• Filed: 05/25/2005
• Published: 12/29/2005
• Est. Priority Date: 06/29/2004
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Mobile Display Company Limited (Samsung Electronics Co. Ltd.)
• Inventors: Eom, Ki-Myeong, Oh, Choon-Yul
• Granted Patent: US 7,408,533 B2
• Time in Patent Office: Days
• US Class Current: 345/76
• 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 2300/0852 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 2310/0251 Precharge or discharge of pixel before applying new pixel voltage
• 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

Abstract

A light emitting display includes pixel circuits capable of compensating for the threshold voltages of their driving transistors. Each pixel circuit includes a driving transistor, a capacitor having one end coupled to a gate electrode of the driving transistor, a first switch coupled between the gate electrode of the driving transistor and a first main electrode, which is turned on in response to a first level of a first control signal for diode-coupling the driving transistor, and a second switch turned on in response to a second level of a second control signal to transmit current flowing out of the first main electrode of the driving transistor to a light emitting element. The second switch is turned on when the first switch is turned on for a first period longer than 0.05 μs and shorter than 2.5 μs. The second switch is turned on when the first switch is turned off.

Claims

1. A light emitting display comprising:

a plurality of scan lines for transmitting a select signal;

a plurality of data lines for transmitting a data voltage; and

a plurality of pixel circuits, each coupled to at least one of the plurality of scan lines and at least one of the plurality of data lines, at least one of the pixel circuits comprising;

a first transistor;

a first capacitor having one end coupled to a gate electrode of the first transistor;

a first switch coupled between the gate electrode and a first main electrode of the first transistor, wherein the first switch is turned on in response to a first level of a first control signal, thereby diode-coupling the first transistor;

a light emitting element for emitting light corresponding to a current flowing out of the first main electrode of the first transistor; and

a second switch being turned on in response to a second level of a second control signal for transmitting the current flowing out of the first main electrode of the first transistor,

wherein the second switch is turned on during a first period when the first switch is turned on, the second switch is turned off after the first period, and the second switch is turned on when the first switch is turned off.

2. The light emitting display of claim 1, wherein the first period is longer than 0.05 μ

s.

3. The light emitting display of claim 1, wherein the first period is shorter than 2.5 μ

s.

4. The light emitting display of claim 1, wherein the at least one of the pixel circuits further includes:

a third switch being turned on in response to a third level of a select signal for transmitting the data signal to an other end of the first capacitor;

a second capacitor having one end coupled to a first power line and an other end coupled to the other end of the first capacitor; and

a fourth switch being turned on in response to a fourth level of a third control signal to be coupled to the second capacitor in parallel.

5. The light emitting display of claim 4, wherein the first control signal is a previous select signal applied prior to the select signal, and the first level is equal to the third level.

6. The light emitting display of claim 4, wherein the third control signal is equal to the first control signal, and the fourth level is equal to the first level.

7. The light emitting display of claim 6, wherein the second switch is turned on when the first switch, the third switch and the fourth switch are turned off.

8. The light emitting display of claim 6, wherein the select signal having the third level is applied after the second period during which a previous select signal is applied.

9. The light emitting display of claim 1, wherein the at least one of the pixel circuits further includes:

a third switch being turned on in response to a third level of a select signal for transmitting the data signal to a second main electrode of the first transistor; and

a fourth switch being turned on in response to a fifth level of a fourth control signal for transmitting the data signal transmitted through the third switch to an other end of the first capacitor.

10. The light emitting display of claim 9, wherein the first control signal and the fourth control signal are a select signal.

11. The light emitting display of claim 1, wherein the at least one of the pixel circuits further includes:

a third switch being turned on in response to a third level of a select signal for transmitting the data signal to the other end of the first capacitor; and

a second capacitor coupled at one end to a first power line and at another end to an other end of the first capacitor.

12. A method for driving a light emitting display including a capacitor having a first electrode coupled to a first power source, a driving transistor having a gate electrode coupled to a second electrode of the capacitor, and a light emitting element for emitting light based on a current applied from the driving transistor, the method comprising:

transmitting the current from the driving transistor to the light emitting element when the driving transistor is in a diode-coupled state;

coupling the light emitting element to the driving transistor; and

transmitting the current from the driving transistor to the light emitting element when the first power source is coupled to a source electrode of the driving transistor,

wherein the current is transmitted from the driving transistor to the light emitting element when the driving transistor is diode-coupled for a time longer than 0.05 μ

s.

13. The method of claim 12, wherein the current is transmitted from the driving transistor to the light emitting element when the driving transistor is diode-coupled for a time shorter than 2.5 μ

s.

14. The method of claim 12, further comprising applying a data voltage to the capacitor before coupling the light emitting element to the driving transistor.

15. The method of claim 12, wherein coupling the light emitting element to the driving transistor further comprising applying a data voltage to the capacitor.