EL display apparatus

Patent metadata

Field	Value
Publication number	US-9959809-B2
Application number	US-201715492033-A
Country	US
Kind code	B2
Filing date	Apr 20, 2017
Priority date	Sep 7, 2001
Publication date	May 1, 2018
Grant date	May 1, 2018

Abstract

An EL display apparatus according to the present invention includes an EL device adapted to emit light at a luminance corresponding to a current fed thereto. A source driver outputs a current higher than a current corresponding to an analog video signal to the EL device through a source signal line. This operation charges/discharges a parasitic capacitance present in the source signal line. A second gate driver circuit controls a transistor formed between the EL device and the source driver to operate so that the EL device is fed with the current for only a part of a one-frame period. As a result, the El device emits light for only the part of the period.

First claim

What is claimed is:

1. An EL display apparatus comprising:
a display screen including pixels arranged in a matrix, each of the pixels including an EL device and a pixel circuit;
a source driver circuit configured to output an analog video signal to each of the pixels;
a source signal line through which the analog video signal output from the source driver circuit is transmitted; and
a gate driver circuit which includes a first gate driver circuit, a second gate driver circuit, a first gate signal line through which a first selection voltage or a first non-selection voltage output from the first gate driver circuit is transmitted, and a second gate signal line through which a second selection voltage or a second non-selection voltage output from the second gate driver circuit is transmitted, wherein
the pixel circuit of each of the pixels includes a driving transistor configured to supply a luminescence-causing current to the EL device, a first switching transistor, and a second switching transistor,
the first switching transistor is disposed on a path through which the luminescence-causing current flows,
the second switching transistor is configured to apply the analog video signal, which is output from the source driver circuit, to the driving transistor,
a gate terminal of the first switching transistor is connected to the first gate signal line,
a gate terminal of the second switching transistor is connected to the second gate signal line,
the first switching transistor and the second switching transistor are independently on/off controlled by the first gate driver circuit and the second gate driver circuit,
the source driver circuit is a semiconductor chip and is attached to the EL display apparatus, and
an output terminal of the source driver circuit is connected to the source signal line.

2. The EL display apparatus according to claim 1 , wherein the gate driver circuit is configured to receive a control signal that is level-shifted by the source driver circuit.

3. The EL display apparatus according to claim 1 , wherein each of the pixels further includes an encapsulating film that seals the EL device.

4. The EL display apparatus according to claim 1 , wherein
the pixel circuit of each of the pixels further includes a third switching transistor,
a first terminal of the third switching transistor is connected to a gate terminal of the driving transistor,
a second terminal of the third switching transistor is connected to a terminal of the driving transistor other than the gate terminal of the driving transistor, and
a gate terminal of the third switching transistor is connected to the second gate signal line.

5. The EL display apparatus according to claim 4 , wherein the third switching transistor includes a multigate structure.

6. The EL display apparatus according to claim 1 , wherein
the first gate driver circuit is disposed at a first side of the display screen,
the second gate driver circuit is disposed at a second side of the display screen,
the pixel circuit of each of the pixels further includes the EL device, and
the first switching transistor is configured to control the luminescence-causing current supplied to the EL device.

7. The EL display apparatus according to claim 1 , further comprising:
a power supply including a cathode wire and an anode wire, wherein
the power supply is configured to generate a cathode voltage and to supply the cathode voltage to the display screen through the cathode wire, and
the power supply is configured to generate an anode voltage and to supply the anode voltage to the display screen through the anode wire.

8. The EL display apparatus according to claim 1 , wherein
the pixels arranged in the matrix on the display screen include at least pixels of a first color and pixels of a second color, and
a size of the pixels of the first color is different from a size of the pixels of the second color.

9. The EL display apparatus according to claim 1 , wherein
the gate driver circuit and the driving transistor of the pixel circuit of each of the pixels is formed on a substrate, and
the source driver circuit is mounted on the substrate.

10. The EL display apparatus according to claim 1 , wherein the gate driver circuit, the driving transistor, the first switching transistor, and the second switching transistor are formed by a same fabrication process.

11. The EL display apparatus according to claim 10 , wherein the gate driver circuit, the driving transistor, the first switching transistor, and the second switching transistor are formed by the same fabrication process using low temperature polysilicon technology.

12. The EL display apparatus according to claim 1 , wherein
the source driver circuit is connected to the source signal line,
the source driver circuit is configured to supply a signal voltage to the gate terminal of the driving transistor,
the driving transistor is configured to supply a current to the EL device which is N times as large as a predetermined value, and
N is greater than one.

13. The EL display apparatus according to claim 1 , wherein the driving transistor is configured to supply the current to the EL device which is N times as large as the predetermined value to achieve a gray scale display indicated by the analog video signal.

14. The EL display apparatus according to claim 1 , wherein
the first gate driver circuit includes first gate signal lines, and
the first gate driver circuit is configured to select a plurality of the first gate signal lines simultaneously.

15. The EL display apparatus according to claim 1 , wherein
the first switching transistor and the second switching transistor are independently on/off controlled by the first gate driver circuit and the second gate driver circuit to vary a duty ratio of the EL device of each of the pixels during a display period.

16. An electronic device, comprising:
the EL display apparatus according to claim 1 .

17. The EL display apparatus according to claim 1 , wherein the first gate driver circuit includes a first shift register circuit, and the second gate driver circuit includes a second shift register circuit.

18. The EL display apparatus according to claim 1 , wherein the first gate driver circuit is configured to scan a first gate signal line, and the second gate driver circuit is configured to scan a second gate signal line.

19. A method of controlling an EL display apparatus,
the EL display apparatus comprising:
a display screen including pixels arranged in a matrix, each of the pixels including an EL device and a pixel circuit;
a source driver circuit configured to output an analog video signal to each of the pixels;
a source signal line through which the analog video signal output from the source driver circuit is transmitted; and
a gate driver circuit which includes a first gate driver circuit, a second gate driver circuit, a first gate signal line through which a first selection voltage or a first non-selection voltage output from the first gate driver circuit is transmitted, and a second gate signal line through which a second selection voltage or a second non-selection voltage output from the second gate driver circuit is transmitted,

the pixel circuit of each of the pixels including a driving transistor configured to supply a luminescence-causing current to the EL device, a first switching transistor, and a second switching transistor,
the first switching transistor being disposed on a path through which the luminescence-causing current flows,
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Assignees

• Joled Inc

Inventors

• Takahara Hiroshi
• Tsuge Hitoshi

Classifications

• G09G2310/0256

  with the purpose of reversing the voltage across a light emitting or modulating element within a pixel · CPC title

• G09G2320/0257

  Reduction of after-image effects · CPC title

• G09G2310/0218

  with collection of electrodes in groups for n-dimensional addressing · CPC title

• G09G2320/06

  Adjustment of display parameters · CPC title

• G09G2300/0852

  being a dynamic memory with more than one capacitor · CPC title