Organic EL display device and driving circuits

• US 6,972,526 B2
• Filed: 05/27/2003
• Issued: 12/06/2005
• Est. Priority Date: 05/28/2002
• Status: Active Grant

• Current Assignee: ROHM Co., Ltd.
• Original Assignee: ROHM Co., Ltd.
• Inventors: Abe, Shinichi
• Primary Examiner(s): TRAN, THUY V
• Application Number:
  US10/444,999
• Publication Number:
  US 20030223275A1
• Time in Patent Office: 924 Days
• Field of Search: 315/160, 315/167, 315/169.2, 315/169.3, 315291-292, 315/307, 345/211, 345/212, 345 76- 77
• US Class Current: 315/169.3
• CPC Class Codes: G11C 5/147 Voltage reference generators, voltage or current regulators; Internally lowered supply levels; Compensation for voltage drops G11C5/141 takes precedence

Abstract

A drive current of every terminal pin is regulated according to data stored in a rewritable non-volatile memory by ON/OFF switching the data by a switch circuit. By writing data necessary for luminance regulation for correcting luminance variation or luminance unevenness in the non-volatile memory, luminance variation or luminance unevenness is reduced.

Claims

1. A drive current regulator circuit of an organic EL element drive circuit, for regulating a drive current of one of terminal pins of an organic EL display panel, comprising:

a switch circuit ON/OFF controlled according to data stored in a memory; and

a current generator circuit provided for every one of said terminal pins and having a first current mirror circuit including an input side drive transistor and first and second output side transistors connected in current mirror to said input side drive transistor, said second output side transistor being connected in parallel to said first output side transistor through said switch circuit to generate a predetermined current at an output of said first output side transistor,

said memory being a non-volatile memory written with said data or a volatile memory written with said data written in a non-volatile memory, said memory being adapted to regulate the drive current according to the predetermined current.

2. A drive current regulator circuit of an organic EL element drive circuit, as claimed in claim 1, further comprising an output stage current source for generating the drive currents of said terminal pins, wherein said first current mirror circuit is provided in a drive stage for driving said output stage current source.

3. A drive current regulator circuit of an organic EL element drive circuit, as claimed in claim 2, wherein a plurality of series circuits each including said second output side transistor and said switch circuit are connected in parallel to said first output side transistor, said non-volatile memory includes a plurality of shift registers each of which has a plurality of stages provided corresponding to a plurality of said terminal pins of said organic EL display panel, said stages corresponding to said switch circuits of said series circuits, respectively, outputs of said stages being supplied to said respective switch circuits.

4. A drive current regulator circuit of an organic EL element drive circuit, as claimed in claim 2, wherein a plurality of series circuits each including said second output side transistor and said switch circuit are connected in parallel to said first output side transistor, said memory being a volatile memory written with data written in a non-volatile memory or written with data transferred from a non-volatile memory provided externally of said drive current regulator circuit, the data is written in said non-volatile memory through a processor or a controller, said volatile memory includes a plurality of shift registers each of which has a plurality of stages provided correspondingly to a plurality of said terminal pins of said organic EL display panel, said stages corresponding to said switch circuits of said series circuits, respectively, outputs of said stages being supplied to said respective switch circuits.

5. An organic EL element drive circuit comprising a drive current regulator circuit as claimed in claim 2, wherein said drive stage includes a D/A converter circuit responsive to the data for generating a drive current for driving an output stage current source, said D/A converter circuit includes a second current mirror circuit, the predetermined current drives said input side transistor of said second current mirror circuit of said DIA converter circuit.

6. An organic EL element drive circuit as claimed in claim 5, wherein a plurality of input side transistors of said second current mirror circuit are connected in parallel to each other, a current value at, which the pin drive current becomes a peak, is generated at said output of said D/A converter circuit by the predetermined current in at least one of the plurality of said input side transistors and a current value at which the pin drive current becomes normal, is generated at said output of said D/A converter circuit by branching the predetermined current in said at least one input side transistor to at least another of the plurality of said input side transistors parallel to said at least one input side transistor.

7. A drive current regulator circuit of an organic EL element drive circuit, as claimed in claim 1, wherein said memory is a volatile memory written with data transferred from a non-volatile memory provided externally of said drive current regulator circuit.

8. An organic EL display device comprising:

an organic EL display panel;

an output stage for current-driving a plurality of terminal pins of said organic EL display panel; and

a drive current regulator circuit of an organic EL element drive circuit for regulating a drive current for said terminal pins of said output stage, said drive current regulator circuit comprising a switch circuit ON/OFF controlled according to data stored in a memory and a current generator circuit provided for every one of said terminal pins of said organic EL display panel, and having a first current mirror circuit including an input side drive transistor and first and second output side transistors connected in current mirror to said input drive transistor, said second output side transistor being connected in parallel to said first output side transistor through said switch circuit to generate a predetermined current at an output of said first output side transistor,

said memory being a non-volatile memory written with said data or a volatile memory written with said data written in a non-volatile memory, said memory being adapted to regulate the drive current according to the predetermined current.

9. An organic EL display device as claimed in claim 8, further comprising an output stage current source for generating the terminal pin drive current, wherein said current generator circuit is provided in a drive stage for driving said output stage current source.

10. An organic EL display device as claimed in claim 9, wherein a plurality of series circuits each including said second output side transistor and said switch circuit are connected in parallel to said first output side transistor, said non-volatile memory includes a plurality of shift registers each of which has a plurality of stages provided corresponding to a plurality of terminal pins of said organic EL display panel, said stages corresponding to said switch circuits of said series circuits, respectively, outputs of said stages being supplied to said respective switch circuits.

11. An organic EL display device as claimed in claim 9, wherein a plurality of series circuits each including said second output side transistor and said switch circuit are connected in parallel to said first output side transistor, said memory being a volatile memory written with data written in a non-volatile memory or written with data transferred from a non-volatile memory provided externally of said drive current regulator circuit, the data is written in said non-volatile memory through a processor or a controller, said volatile memory includes a plurality of shift registers each of which has a plurality of stages provided corresponding to a plurality of terminal pins of said organic EL display panel, said stages corresponding to said switch circuits of said series circuits, respectively, outputs of said stages being supplied to said respective switch circuits.

12. An organic EL display device as claimed in claim 9, wherein said drive stage comprises a D/A converter circuit responsive to a display data for generating a drive current for driving said output stage current source, said D/A converter circuit including a second current mirror circuit, the predetermined current driving an input side transistor of said second current mirror circuit of said D/A converter circuit.

13. An organic EL display device as claimed in claim 12, wherein a plurality of input side transistors of said second current mirror circuit are connected in parallel to each other, a current value at which the pin drive current becomes a peak, is generated at said output of said D/A converter circuit by the predetermined current in at least one of the plurality of said input side transistors and a current value at which the pin drive current becomes normal, is generated at said output of said D/A converter circuit by branching the predetermined current in said at least one input side transistOr to at least another of the plurality of said input side transistors parallel to said at least one input side transistor.

14. An organic EL display device as claimed in claim 8, wherein said memory is a volatile memory written with data transferred from a non-volatile memory provided externally of said drive current regulator circuit.