Display apparatus and method of driving same
A display apparatus including a pixel array and a driver configured to drive the pixel array, the pixel array having scanning lines as rows, signal lines as columns, a matrix of pixels disposed at respective intersections of the scanning lines and the signal lines, and power supply lines disposed along respective rows of the pixels, the driver having a main scanner for successively supplying control signals to the scanning lines to perform line-sequential scanning on the rows of the pixels, a power supply scanner for supplying a power supply voltage, which selectively switches between a first potential and a second potential, to the power supply lines in synchronism with the line-sequential scanning, and a signal selector for supplying a signal potential, which serves as a video signal, and a reference potential to the signal lines as the columns in synchronism with the line-sequential scanning.
1. A display apparatus comprising:
a pixel array having scanning lines, signal lines, pixels forming a matrix, and power supply lines,
a power supply scanner configured to supply a first potential and a second potential to said power supply lines,
at least one of the pixels including a light-emitting device, a sampling transistor, a drive transistor, and a retention capacitor,
the sampling transistor configured to sample a signal potential supplied from one of the signal lines and to retain the sampled signal potential in the retention capacitor,
the drive transistor configured to supply a current from the power supply line at the first potential to the light-emitting device depending on the signal potential,
wherein a potential of a corresponding one of said power supply lines is switched from the first potential to the second potential after the sampling transistor is rendered conductive at a beginning of a field period and a potential of the one of the signal lines is at a reference potential,
wherein a potential of the one of the signal lines is switched from the reference potential to the signal potential at a first timing after the sampling transistor is rendered conductive and a potential of the corresponding power supply line is the first potential,
wherein the sampling transistor is rendered nonconductive at a second timing occurring after the first timing while the potential of the one of the signal lines remains at the signal potential and the potential of the corresponding power supply line remains at the first potential, and
wherein a period between the first timing and the second timing is appropriately set to correct the sampled signal potential as it is retained in the retention capacitor with respect to a mobility of the drive transistor.
2. The display apparatus according to claim 1 , wherein a video signal is supplied as the signal potential through the one of the signal lines, and a relative phase difference between the video signal and a control signal is adjusted to optimize the period between the first timing and the second timing, the control signal being applied to the scanning line to render the sampling transistor conductive or nonconductive.
3. The display apparatus according to claim 1 , wherein a video signal is supplied as the signal potential through the signal line, and a gradient is applied to a positive-going edge of the video signal that switches from the reference potential to the signal potential, which allows the period between the first timing and the second timing to automatically follow the signal potential.
4. The display apparatus according to claim 1 , wherein when the sampled signal potential is retained by the retention capacitor, the sampling transistor is rendered nonconductive to electrically disconnect a gate of the drive transistor from the signal line, so that a gate potential of the drive transistor is linked to a variation of a source potential of the drive transistor to keep constant a voltage between the gate and a source of the drive transistor.
5. An electronic device including a display apparatus, the display apparatus comprising:
a pixel array having scanning lines, signal lines, pixels forming a matrix, and power supply lines,
a power supply scanner configured to supply a first potential and a second potential to said power supply lines,
at least one of the pixels including a light-emitting device, a sampling transistor, a drive transistor, and a retention capacitor,
the sampling transistor configured to sample a signal potential supplied from one of the signal lines, and retain the sampled signal potential in the retention capacitor,
the drive transistor configured to supply a current from the power supply line at the first potential to the light-emitting device depending on the signal potential,
wherein a potential of a corresponding one of said power supply lines is switched from the first potential to the second potential after the sampling transistor is rendered conductive at a beginning of a field period and a potential of the one of the signal lines is at a reference potential,
wherein a potential of the one of the signal lines is switched from the reference potential to the signal potential at a first timing after the sampling transistor is rendered conductive and a potential of the corresponding power supply line is the first potential,
wherein the sampling transistor is rendered nonconductive at a second timing occurring after the first timing while the potential of the one of the signal lines remains at the signal potential and the potential of the corresponding power supply line remains at the first potential, and
wherein a period between the first timing and the second timing is appropriately set to correct the sampled signal potential as it is retained in the retention capacitor with respect to a mobility of the drive transistor.
6. The electronic device according to claim 5 , wherein a video signal is supplied as the signal potential through the signal line, and a relative phase difference between the video signal and a control signal that is applied to the scanning line to render the sampling transistor conductive or nonconductive is adjusted to optimize the period between the first timing and the second timing.
7. The electronic device according to claim 5 , wherein a video signal is supplied as the signal potential through the signal line, and a gradient is applied to a positive-going edge of the video signal that switches from the reference potential to the signal potential, which allows the period between the first timing and the second timing to automatically follow the signal potential.
8. The electronic device according to claim 5 , wherein when the sampled signal potential is retained by the retention capacitor, the sampling transistor is rendered nonconductive to electrically disconnect a gate of the drive transistor from the signal line, so that a gate potential of the drive transistor is linked to a variation of a source potential of the drive transistor to keep constant a voltage between the gate and a source of the drive transistor.
9. A display apparatus comprising:
a pixel array having scanning lines, signal lines, a matrix of pixels, and power supply lines,
a power supply scanner configured to supply a first potential and a second potential to said power supply lines,
at least one of the pixels including a light-emitting device, a sampling transistor, a drive transistor, and a retention capacitor,
the sampling transistor configured to sample a signal potential supplied from the signal line, and retain the sampled signal potential in the retention capacitor,
the drive transistor configured to supply a current from the power supply line at the first potential to the light-emitting device depending on the signal potential,
wherein a potential of a corresponding one of said power supply lines is switched from the first potential to the second potential after the sampling transistor is rendered conductive at a beginning of a field period and a potential of the one of the signal lines is at a reference potential,
wherein a potential of the one of the signal lines is switched from the reference potential to the signal potential at a first timing after the sampling transistor is rendered conductive and a potential of the corresponding power supply line is the first potential,
wherein the sampling transistor is rendered nonconductive at a second timing occurring after the first timing while the potential of the one of the signal lines remains at the signal potential and the potential of the corresponding power supply line remains at the first potential, and
wherein a gate-to-source voltage of the drive transistor is configured to decrease based on a negative feedback which is applied to make a correcting variable greater when a mobility of the drive transistor is greater and also to make the correcting variable smaller when the mobility is smaller.
10. The display apparatus according to claim 9 , wherein a period between the first timing and the second timing is appropriately set to correct the sampled signal potential as it is retained in the retention capacitor with respect to the mobility of the drive transistor.