Display device, driving method of the same and electronic equipment having the same
View Patent ↗A pixel circuit of a display device of the present invention has a drive transistor which serves also as a transistor adapted to control the emission and non-emission periods of an organic EL element or other elements. A final stage buffer in an output circuit of a write scan circuit (WS) has its power supply separated from the power supply of circuit portions of a previous stage. In a first embodiment, a scan signal WS from the write scan circuit is activated instantaneously. In a second embodiment, the trailing edge of the scan signal WS falls slowly. This allows for writing of an input signal voltage in a stable manner.
1. A display device comprising:
a pixel array section including pixels arranged in a matrix form, each pixel having an electro-optical element, a write transistor adapted to sample and write an input signal voltage, a holding capacitance adapted to hold the input signal voltage written by the write transistor and a drive transistor adapted to drive the electro-optical element based on the input signal voltage held by the holding capacitance; and
a scan circuit including a final stage buffer, whose power supply is separated from circuit portions of a previous stage, and configured to apply a scan signal from the previous stage buffer to the write transistor to select and scan the pixels in the pixel array section on a row by row basis;
wherein a supply voltage in pulse form is supplied to the power supply of the final stage buffer so that the scan signal rises at the leading edge of the supply voltage.
2. The display device of claim 1 ,
wherein each of the pixels in the pixel array section performs a correction adapted to cancel the dependence of a drain-to-source current of the drive transistor on a mobility by feeding back the drain-to-source current of the drive transistor to the gate input during the write period of the input signal voltage by the write transistor.
3. A driving method of a display device, the display device comprising:
a pixel array section including pixels arranged in a matrix form, each pixel having an electro-optical element, a write transistor adapted to sample and write an input signal voltage, a holding capacitance adapted to hold the input signal voltage written by the write transistor and a drive transistor adapted to drive the electro-optical element based on the input signal voltage held by the holding capacitance; and
a scan circuit including a final stage buffer, whose power supply is separated from circuit portions of a previous stage, and configured to apply a scan signal from the previous stage buffer to the write transistor to select and scan the pixels in the pixel array section on a row by row basis;
wherein a supply voltage in pulse form is supplied to the power supply of the final stage buffer so that the scan signal rises at the leading edge of the supply voltage.
4. Electronic equipment having a display device, the display device comprising:
a pixel array section including pixels arranged in a matrix form, each pixel having an electro-optical element, a write transistor adapted to sample and write an input signal voltage, a holding capacitance adapted to hold the input signal voltage written by the write transistor and a drive transistor adapted to drive the electro-optical element based on the input signal voltage held by the holding capacitance; and
a scan circuit including a final stage buffer, whose power supply is separated from circuit portions of a previous stage, and configured to apply a scan signal from the previous stage buffer to the write transistor to select and scan the pixels in the pixel array section on a row by row basis;
wherein a supply voltage in pulse form is supplied to the power supply of the final stage buffer so that the scan signal rises at the leading edge of the supply voltage.
5. A display device comprising:
a pixel array section including pixels arranged in a matrix form, each pixel having an electro-optical element, a write transistor adapted to sample and write an input signal voltage, a holding capacitance adapted to hold the input signal voltage written by the write transistor and a drive transistor adapted to drive the electro-optical element based on the input signal voltage held by the holding capacitance; and
a scan circuit including a final stage buffer, whose power supply is separated from circuit portions of a previous stage, and configured to apply a write pulse, which is based on an input pulse to the final stage buffer, to the write transistor to select and scan the pixels in the pixel array section on a row by row basis;
wherein a supply voltage, whose fall time is slower than that of the input pulse, is supplied to the power supply of the final stage buffer so that the write pulse falls at the trailing edge of the supply voltage.
6. The display device of claim 5 ,
wherein each of the pixels in the pixel array section performs a correction adapted to cancel the dependence of a drain-to-source current of the drive transistor on a mobility by feeding back the drain-to-source current of the drive transistor to the gate input during the write period of the input signal voltage by the write transistor.
7. The display device of claim 5 ,
wherein the supply voltage is supplied commonly to all the final stage buffers of the scan circuit.
8. A driving method of a display device, the display device comprising:
a pixel array section including pixels arranged in a matrix form, each pixel having an electro-optical element, a write transistor adapted to sample and write an input signal voltage, a holding capacitance adapted to hold the input signal voltage written by the write transistor and a drive transistor adapted to drive the electro-optical element based on the input signal voltage held by the holding capacitance; and
a scan circuit including a final stage buffer, whose power supply is separated from circuit portions of a previous stage, and configured to apply a write pulse, which is based on an input pulse to the final stage buffer, to the write transistor to select and scan the pixels in the pixel array section on a row by row basis;
wherein a supply voltage, whose fall time is slower than that of the input pulse, is supplied to the power supply of the final stage buffer so that the write pulse falls at the trailing edge of the supply voltage.
9. Electronic equipment having a display device, the display device comprising:
a pixel array section including pixels arranged in a matrix form, each pixel having an electro-optical element, a write transistor adapted to sample and write an input signal voltage, a holding capacitance adapted to hold the input signal voltage written by the write transistor and a drive transistor adapted to drive the electro-optical element based on the input signal voltage held by the holding capacitance; and
a scan circuit including a final stage buffer, whose power supply is separated from circuit portions of a previous stage, and configured to apply a write pulse, which is based on an input pulse to the final stage buffer, to the write transistor to select and scan the pixels in the pixel array section on a row by row basis;
a supply voltage, whose fall time is slower than that of the input pulse, is supplied to the power supply of the final stage buffer so that the write pulse falls at the trailing edge of the supply voltage.