Pixel circuit, display device, electronic device, and pixel circuit driving method
View Patent ↗Disclosed herein is a pixel circuit including: a light emitting element; a storage capacitor; a writing transistor for writing a driving voltage corresponding to a video signal to the storage capacitor; and a driving transistor for driving the light emitting element on a basis of the driving voltage written to the storage capacitor, wherein a characteristic of the writing transistor is controllable in such a manner as to be operatively associated with a process of writing the driving voltage corresponding to the video signal to the storage capacitor.
1. A pixel circuit comprising:
a light emitting element;
a storage capacitor;
a writing transistor for writing a driving voltage corresponding to a video signal to the storage capacitor; and
a driving transistor for driving the light emitting element on a basis of the driving voltage written to the storage capacitor,
wherein a characteristic of the writing transistor is controllable in such a manner as to be operatively associated with a process of writing the driving voltage corresponding to the video signal to the storage capacitor,
a writing capability of the writing transistor is increased in a period of the process of writing the driving voltage corresponding to the video signal to the storage capacitor, and
a threshold voltage of the writing transistor is decreased simultaneously with a start of the process of writing the driving voltage corresponding to the video signal to the storage capacitor.
2. The pixel circuit according to claim 1 , further comprising
a characteristic controlling section configured to control the characteristic of the writing transistor in such a manner as to be operatively associated with the process of writing the driving voltage corresponding to the video signal to the storage capacitor.
3. The pixel circuit according to claim 1 ,
wherein the writing capability of the writing transistor is increased simultaneously with a start of the process of writing the driving voltage corresponding to the video signal to the storage capacitor.
4. The pixel circuit according to claim 1 , further comprising
a pixel section in which light emitting elements are arranged,
wherein a characteristic controlling section controls a characteristic of the writing transistor in each light emitting element.
5. The pixel circuit according to claim 4 ,
wherein the pixel section has the light emitting elements arranged in a form of a two-dimensional matrix.
6. A pixel circuit comprising:
a light emitting element;
a storage capacitor;
a writing transistor for writing a driving voltage corresponding to a video signal to the storage capacitor; and
a driving transistor for driving the light emitting element on a basis of the driving voltage written to the storage capacitor,
wherein a characteristic of the writing transistor is controllable in such a manner as to be operatively associated with a process of writing the driving voltage corresponding to the video signal to the storage capacitor,
the writing transistor has a characteristic control terminal capable of controlling a threshold voltage, and
a characteristic controlling section supplies a control signal for controlling the threshold voltage to the characteristic control terminal.
7. The pixel circuit according to claim 6 ,
wherein the writing transistor is a metal oxide film type field effect transistor.
8. The pixel circuit according to claim 6 ,
wherein the writing transistor is a back gate type thin film transistor.
9. The pixel circuit according to claim 6 ,
wherein a capacitance element is disposed between the characteristic control terminal and a control electrode terminal of the writing transistor, the control electrode terminal being supplied with a control signal for controlling conduction/non-conduction of the writing transistor.
10. The pixel circuit according to claim 9 , further comprising
a time constant adjusting section configured to adjust a time constant of the signal supplied to the characteristic control terminal via the capacitance element.
11. The pixel circuit according to claim 10 ,
wherein the time constant adjusting section has a resistance element connected to the characteristic control terminal.
12. The pixel circuit according to claim 6 ,
wherein a capacitance element is disposed between the characteristic control terminal and a video signal line for transmitting the video signal.
13. The pixel circuit according to claim 6 ,
wherein a pulse signal corresponding to a control signal for controlling conduction/non-conduction of the writing transistor is supplied to the characteristic control terminal.
14. The pixel circuit according to claim 13 , further comprising at least one of:
a pulse width adjusting section configured to adjust a pulse width of the control signal for controlling the conduction/non-conduction of the writing transistor, the pulse width setting the writing transistor in a conducting state, and supply the control signal to the characteristic control terminal; and
an amplitude adjusting section configured to adjust an amplitude of the signal supplied to the characteristic control terminal.
15. A display device comprising:
a plurality of pixel circuits including a light emitting element, a storage capacitor, a writing transistor for writing a driving voltage corresponding to a video signal to the storage capacitor, and a driving transistor for driving the light emitting element on a basis of the driving voltage written to the storage capacitor, the pixel circuits being arranged; and
a characteristic controlling section configured to control a characteristic of the writing transistor in such a manner as to be operatively associated with a process of writing the driving voltage corresponding to the video signal to the storage capacitor, wherein
a writing capability of the writing transistor is increased in a period of the process of writing the driving voltage corresponding to the video signal to the storage capacitor, and
a threshold voltage of the writing transistor is decreased simultaneously with a start of the process of writing the driving voltage corresponding to the video signal to the storage capacitor.
16. A display device comprising:
a plurality of pixel circuits;
a plurality of signal lines; and
a plurality of scanning lines,
wherein the pixel circuits include a light emitting element, a storage capacitor, a writing transistor, and a driving transistor,
the writing transistor is set in a conducting state according to a control signal from a scanning line, and supplies a video signal from a signal line to the storage capacitor,
the storage capacitor retains a driving voltage corresponding to the supplied video signal,
the driving transistor is driven so as to feed a current through the light emitting element on a basis of the driving voltage,
the writing transistor includes a back gate terminal and a gate terminal, and
a capacitance element and a resistance element are connected between the back gate terminal and the gate terminal.
17. An electronic device comprising:
a plurality of pixel circuits including a light emitting element, a storage capacitor, a writing transistor for writing a driving voltage corresponding to a video signal to the storage capacitor, and a driving transistor for driving the light emitting element on a basis of the driving voltage written to the storage capacitor, the pixel circuits being arranged;
a signal generating section for generating the video signal to be supplied to the writing transistor; and
a characteristic controlling section configured to control a characteristic of the writing transistor in such a manner as to be operatively associated with a process of writing the driving voltage corresponding to the video signal to the storage capacitor, wherein
a writing capability of the writing transistor is increased in a period of the process of writing the driving voltage corresponding to the video signal to the storage capacitor, and
a threshold voltage of the writing transistor is decreased simultaneously with a start of the process of writing the driving voltage corresponding to the video signal to the storage capacitor.
18. A pixel circuit driving method for driving a pixel circuit, the pixel circuit including a writing transistor for writing a driving voltage corresponding to a video signal to a storage capacitor and a driving transistor for driving a display section, the driving method comprising
controlling a characteristic of the writing transistor in such a manner as to be operatively associated with a process of writing the driving voltage corresponding to the video signal to the storage capacitor, wherein a writing capability of the writing transistor is increased in a period of the process of writing the driving voltage corresponding to the video signal to the storage capacitor, and a threshold voltage of the writing transistor is decreased simultaneously with a start of the process of writing the driving voltage corresponding to the video signal to the storage capacitor.