Electroluminescence display which realizes high speed operation and high contrast

• US 6,531,827 B2
• Filed: 08/09/2001
• Issued: 03/11/2003
• Est. Priority Date: 08/10/2000
• Status: Expired due to Term

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: NEC Corporation
• Inventors: Kawashima, Shingo
• Primary Examiner(s): Ho, Tan
• Application Number:
  US09/924,498
• Publication Number:
  US 20020067134A1
• Time in Patent Office: 579 Days
• Field of Search: 315/169.1, 315/169.2, 315/169.3, 315/169.4, 345/89, 345/90, 345/98, 345/100, 345/101, 345/76, 345/204, 345/210, 345/214
• US Class Current: 315/169.3
• CPC Class Codes: G09G 2310/0251 Precharge or discharge of pixel before applying new pixel voltage
• CPC Class Codes: G09G 2320/0252 Improving the response speed
• CPC Class Codes: G09G 2320/041 Temperature compensation
• CPC Class Codes: G09G 3/3216 using a passive matrix

Abstract

An electroluminescence display is composed of an electroluminescence pixel and a driving circuit. The driving circuit drives the electroluminescence pixel to emit light. The driving circuit provides a first drive current, and then provides a second drive current for the electroluminescence pixel. The first drive current is larger than the second drive current, and increases depending on the second drive current.

Claims

1. An electroluminescence display comprising:

an electroluminescence pixel; and

a driving circuit which drives said electroluminescence pixel to emit light, wherein said driving circuit provides a first drive current, and then provides a second drive current for said electroluminescence pixel, and

said first drive current is larger than said second drive current, and increases depending on said second drive current.

2. The electroluminescence display according to claim 1, wherein said second drive current is determined based on a brightness of said light.

3. The electroluminescence display according to claim 1, wherein said first drive current is smaller than a limit current for maintaining a current-brightness property of said electroluminescence pixel substantially linear.

4. The electroluminescence display according to claim 1, wherein said first drive current is k times as large as said second drive current, where k is a constant larger than 1.

5. The electroluminescence display according to claim 4, wherein said k is defined such that

6. The electroluminescence display according to claim 4, wherein said k is determined based on a color of light emitted by said electroluminescence pixel.

7. The electroluminescence display according to claim 1, wherein said driving circuit includes:

a first current source unit generating a first current,

a second current source unit generating a second current, and

a current output unit superposing said first and second current to generate said first drive current.

8. The electroluminescence display according to claim 7, wherein said current output unit generates said second drive current from said first current.

9. A method of operating a electroluminescence display comprising:

providing a first drive current with a electroluminescence pixel; and

providing a second drive current with said electroluminescence pixel after said providing said first drive current, wherein said first drive current is larger than said second drive current, and increases depending on said second drive current.

10. The method according to claim 9, wherein said second drive current is determined based on a brightness of light emitted by said electroluminescence pixel.

11. The method according to claim 9, wherein said providing said first drive current includes:

generating a first current,

generating a second current, and

superposing said first and second current to provide said first drive current, and

said providing said second drive current includes outputting said first current to provide said second drive current.

12. The method according to claim 9 wherein said first drive current is smaller than a limit current for maintaining a current-brightness property of said electroluminescence pixel substantially linear.