Display panel, light emitting display device using the same, and driving method thereof

• US 20050110721A1
• Filed: 10/19/2004
• Published: 05/26/2005
• Est. Priority Date: 11/20/2003
• 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: Shin, Dong-Yong, Matsueda, Yojiro
• Granted Patent: US 7,973,743 B2
• Time in Patent Office: Days
• US Class Current: 345/76
• 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 2310/0248 Precharge or discharge of column electrodes before or after applying exact column voltages
• 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 light emitting display device including data lines, signal lines, pixel circuits, a data driver, and a precharger. Each pixel circuit includes a first switch, a transistor, a capacitor, and a light emitting element. The precharger supplies a precharge current of X times a data current to a corresponding data line in response to a control signal. When the first switch transmits the data current provided from the corresponding data line in response to a first level scan signal while the corresponding data line is precharged, a voltage corresponding to the data current is charged in the capacitor. A current corresponding to the charged voltage is supplied to the light emitting element through the transistor in response to a second level scan signal, and the light emitting element emits light.

Claims

1. A light emitting display device comprising:

a plurality of data lines, arranged in one direction, for transmitting data currents;

a plurality of signal lines, crossing the data lines, for transmitting scan signals;

a plurality of pixel circuits coupled to the data lines and the signal lines, each said pixel circuit formed at an area located where a corresponding said data line and a corresponding said signal line cross over each other, for displaying an image corresponding to a corresponding said data current, which is applied thereto;

a data driver for transmitting the data currents to the data lines; and

a precharger for supplying precharge currents to the data lines in response to a control signal, which is applied thereto.

2. The light emitting display device of claim 1, wherein a magnitude of each said precharge current is X times that of the corresponding said data current, where X is a real number greater than 1.

3. The light emitting display device of claim 1, wherein each said pixel circuit comprises:

a first switch for transmitting the corresponding said data current provided from the corresponding said data line in response to a corresponding said scan signal applied from the corresponding said signal line;

a capacitor for charging a voltage corresponding to the corresponding said data current provided from the first switch;

a light emitting element; and

a first transistor for supplying a current corresponding to the voltage charged in the capacitor to the light emitting element.

4. The light emitting display device of claim 3, wherein the precharger comprises:

a second switch for transmitting a corresponding said precharge current provided from the corresponding said data line in response to the control signal; and

a second transistor for supplying a current corresponding to the corresponding said precharge current to the corresponding said data line.

5. The light emitting display device of claim 4, wherein a ratio of (a channel width)/(a channel length) of the second transistor is X times a ratio of (a channel width)/(a channel length) of the first transistor.

6. The light emitting display device of claim 5, wherein the corresponding said precharge current provided from the corresponding said data line flows through the second transistor in response to the control signal during a first period,

wherein the voltage corresponding to the corresponding said data current provided from the corresponding said data line is charged in the capacitor in response to a first level scan signal of the corresponding said scan signal during a second period, and

wherein the light emitting element emits light according to the current corresponding to the voltage charged in the capacitor in response to a second level scan signal of the corresponding said scan signal during a third period.

7. The light emitting display device of claim 4, wherein a ratio of (a channel width)/(a channel length) of the second transistor is X−

1 times a ratio of (a channel width)/(a channel length) of the first transistor, where X is a real number greater than 1.

8. The light emitting display device of claim 7, wherein a current which is X−

1 times the corresponding said data current in the corresponding said precharge current provided from the corresponding said data line flows through the second transistor in response to the control signal, and a voltage which corresponds to the corresponding said data current is charged in the capacitor in response to a first level scan signal of the corresponding said scan signal during a first period,

wherein the voltage corresponding to the corresponding said data current provided from the corresponding said data line is charged in the capacitor in response to the first level scan signal of the corresponding said scan signal during a second period, and

wherein the light emitting element emits light according to the current corresponding to the voltage charged in the capacitor in response to a second level scan signal of the corresponding said scan signal during a third period.

9. The light emitting display device of claim 3, wherein the first switch is operated in response to a first level scan signal of the corresponding said scan signal provided from the corresponding said signal line, and

wherein the light emitting display device further comprises a third switch for supplying the current provided from the first transistor to the light emitting element in response to a second level scan signal of the corresponding said scan signal provided from the corresponding said signal line.

10. The light emitting display device of claim 9, wherein each said pixel circuit further comprises a fourth switch for charging the voltage corresponding to the corresponding said data current provided from the corresponding said data line in the capacitor in response to the first level scan signal of the corresponding said scan signal.

11. The light emitting display device of claim 3, wherein each said pixel circuit further comprises:

a third transistor for forming a path for transmitting the current provided from the corresponding said data line and supplied through the first switch; and

a third switch for performing a switching operation between the third transistor and the capacitor in response to the corresponding said scan signal,

wherein the first transistor and the third transistor form a current mirror.

12. The light emitting display device of claim 11, wherein a ratio of (a channel width)/(a channel length) of the second transistor is X times a ratio of (a channel width)/(a channel length) of the third transistor.

13. The light emitting display device of claim 11, wherein a ratio of (a channel width)/(a channel length) of the second transistor is X−

1 times a ratio of (a channel width)/(a channel length) of the third transistor.

14. The light emitting display device of claim 4, wherein the precharger is provided on an opposite side of the data driver with respect to the pixel circuits.

15. The light emitting display device of claim 1, wherein the signal lines comprise select signal lines for transmitting first scan signals, and emit select signal lines for transmitting second scan signals, and

wherein each said pixel circuit writes as a voltage the corresponding said data current provided from the corresponding said data line in response to a corresponding said first scan signal, and performs a display operation according to the written voltage in response to a corresponding said second scan signal.

16. A display panel comprising:

a plurality of data lines, arranged in one direction, for transmitting data currents;

a plurality of signal lines, crossing the data lines, for transmitting scan signals; and

a pixel circuit, formed at a pixel area located where one said data line and one said signal line cross over each other, the pixel circuit including a first switch for transmitting one said data current provided from the one said data line in response to one said scan signal applied from the one said signal line, a capacitor for charging a voltage corresponding to the one said data current provided from the first switch, a light emitting element, and a first transistor for supplying a current corresponding to the voltage charged in the capacitor to the light emitting element,

wherein a precharge current which is X times the one said data current is supplied to the one said data line before the one said data current is supplied to the one said data line.

17. The display panel of claim 16, wherein a current which is X−

1 times the one said data current in the precharge current supplied through the one said data line is bypassed when supplying the precharge current, the first switch is turned on in response to the one said scan signal, and the voltage which corresponds to the one said data current is precharged in the capacitor.

18. The display panel of claim 16, wherein a precharger for supplying a precharge current which is X times the one said data current to the one said data line is formed on the display panel.

19. The display panel of claim 18, wherein the precharger comprises:

a second switch for transmitting the precharge current provided from the one said data line in response to the control signal; and

a second transistor for supplying the current corresponding to the precharge current to the one said data line.

20. The display panel of claim 16, wherein the one said signal line comprises a select signal line for transmitting a first said scan signal, and an emit select signal for transmitting a second said scan signal, and

wherein the pixel circuit writes as a voltage the current provided from the one said data line in response to the first said scan signal, and performs a display operation according to the written voltage in response to the second said scan signal.

21. A method for driving a light emitting display device including a pixel circuit formed at a pixel area located where a data line and a signal line cross over each other, the pixel circuit including a capacitor, a transistor for supplying a current corresponding to a voltage charged in the capacitor, and a light emitting element, the method comprising:

(a) supplying a precharge current which is X times the data current to the data line to precharge the data line;

(b) charging a voltage which corresponds to the data current transmitted from the data line in the capacitor in response to a first level scan signal provided from the signal line; and

(c) allowing the light emitting element to emit light in response to a current which corresponds to the voltage charged in the capacitor in response to a second level scan signal provided from the signal line.

22. The method of claim 21, wherein (a) comprises:

supplying the precharge current which is X times the data current, where X is a real number greater than 1;

bypassing the current which is X−

1 times the data current in the precharge current; and

charging the voltage which corresponds to the data current in response to the first level scan signal transmitted from the signal line.

23. The method of claim 21, wherein a time for performing the precharge of the data line is greater than 1/X times a horizontal period of the light emitting display device