Method for manufacturing electroluminescent display device

1. A method for manufacturing an electroluminescent (EL) display device that includes a display screen in which a plurality of pixels are arranged in a matrix, wherein

the plurality of pixels each include an EL element, a driving transistor which supplies a current to the EL element, and a switching transistor,

the EL element includes a first terminal to which a first voltage is applied, and a second terminal, and

the switching transistor includes a gate terminal connected to a gate signal line, a third terminal connected to the second terminal, and a fourth terminal to which a second voltage is applied, the second voltage having a potential higher than a potential of the first voltage, the method comprising:

applying the second voltage to the second terminal via the switching transistor, by applying an ON voltage to the gate signal line,

detecting light emission by the EL element, using an optical detector, in a state in which the ON voltage is being applied to the gate signal line;

detecting a defective pixel by turning on all of the plurality of pixels arranged in the display screen, prior to the applying, and

determining which one of the EL element and a pixel circuit element other than the EL element has a defect, based on a result of the detecting of the light emission by the EL element, wherein

in the determining, the pixel circuit element is determined to be a cause of the defect when the defective pixel includes the EL element whose light emission is detected in the detecting of the light emission, and the EL element is determined to be a cause of the defect when the defective pixel includes the EL element whose light emission is not detected in the detecting of the light emission.

2. The method for manufacturing the EL display device according to claim 1 , wherein

the pixel circuit element includes the switching transistor and the driving transistor.

3. The method for manufacturing the EL display device according to claim 1 , wherein

in the applying, the second voltage is applied to the second terminal via the switching transistor and bypassing the driving transistor, by applying the ON voltage to the gate signal line.

4. The method for manufacturing the EL display device according to claim 1 , wherein

the EL display device includes a source signal line disposed for each of pixel columns of the plurality of pixels, for transmitting a signal voltage reflecting a video signal, to a gate terminal of the driving transistor,

the fourth terminal is connected to the source signal line disposed in an adjacent one of the pixel columns, and

in the applying, the second voltage applied to the source signal line disposed in the adjacent one of the pixel columns is applied to the second terminal via the switching transistor, by applying the ON voltage to the gate signal line.

5. The method for manufacturing the EL display device according to claim 1 , wherein

the display screen includes a first gate driver circuit and a second gate driver circuit,

the plurality of pixels each include a second switching transistor for applying a video signal to the driving transistor, the second switching transistor including a gate terminal connected to a second gate signal line, and

the second gate signal line is driven by the first gate driver circuit and the second gate driver circuit.

6. The method for manufacturing the EL display device according to claim 5 , wherein

the plurality of pixels each include a third switching transistor for performing an offset cancelling operation of the driving transistor, the third switching transistor including a gate terminal connected to a third gate signal line, and

the third gate signal line is driven by the first gate driver circuit and the second gate driver circuit.

7. The method for manufacturing the EL display device according to claim 6 , wherein

the gate signal line which is connected to the gate terminal of the switching transistor is driven by only one of the first gate driver circuit and the second gate driver circuit.

8. The method for manufacturing the EL display device according to claim 7 , wherein

one of the first gate driver circuit and the second gate driver circuit is disposed on a left side of the display screen, and

an other of the first gate driver circuit and the second gate driver circuit is disposed on a right side of the display screen.

9. The method for manufacturing the EL display device according to claim 1 , wherein

in the detecting of the defective pixel, all of the plurality of pixels arranged in the display screen are concurrently turned on.

10. The method for manufacturing the EL display device according to claim 1 , wherein

in the detecting of the light emission by the EL element, only the switching transistor which includes the gate terminal connected to the gate signal line is turned on among transistors of the plurality of pixels.

11. The method for manufacturing the EL display device according to claim 1 , further comprising:

in the applying the second voltage to the second terminal via the switching transistor, selecting the gate signal line for each pixel row.

12. The method for manufacturing the EL display device according to claim 1 , wherein

the plurality of pixels each include a second switching transistor for applying a video signal to the driving transistor,

the second switching transistor of adjacent pixels of the plurality of pixels is connected to different second gate signal lines, and

the method further comprises:

in the detecting of the defective pixel, concurrently or alternately selecting the different second gate signal lines.