Pixel circuit including plurality of switching transistors and capacitors, and display unit
A pixel circuit includes a driving transistor, a write transistor, a first switching transistor, a first storage capacitor, a second and third switching transistors, and a second storage capacitor. The driving transistor controls a current flowing in a light-emitting device. The write transistor controls application of a signal voltage to a source end of the driving transistor. The first switching transistor controls a gate voltage of the driving transistor during correction operation that allows a gate-source voltage of the driving transistor to come close to a threshold voltage of the driving transistor. The second switching and third switching transistors are provided, in series, at an electrically conductive path between the source end of the driving transistor and a first voltage line.
1. A pixel circuit comprising:
a driving transistor configured to control a current flowing in a light-emitting device;
a write transistor configured to control application of a signal voltage to a source end of the driving transistor, the signal voltage corresponding to an image signal;
a first switching transistor configured to control a gate voltage of the driving transistor upon correction operation that allows a gate-source voltage of the driving transistor to come close to a threshold voltage of the driving transistor;
a first storage capacitor provided at an electrically conductive path between a gate of the driving transistor and the source end of the driving transistor;
a second switching transistor and a third switching transistor disposed, in series, so as to selectively provide an electrically conductive path between the source end of the driving transistor and a first voltage line; and
a second storage capacitor provided at an electrically conductive path between the gate of the driving transistor and a node, the node coupling the second switching transistor and the third switching transistor.
2. The pixel circuit according to claim 1 , further comprising:
a fourth switching transistor disposed so as to selectively provide an electrically conductive path between the source end of the driving transistor and the light-emitting device.
3. The pixel circuit according to claim 1 , wherein the first switching transistor is diode-connected.
4. The pixel circuit according to claim 1 , wherein
the second switching transistor is configured to switch between an ON state and an OFF state in response to a first control signal at a gate of the second switching transistor, and
the third switching transistor is configured to switch between an ON state and an OFF state in response to a second control signal at a gate of the third switching transistor.
5. The pixel circuit according to claim 4 , wherein the second switching transistor and the third switching transistor are configured to provide the electrically conductive path between the source end of the driving transistor and the first voltage line when the second switching transistor is in the ON state and the third switching transistor is in the ON state.
6. The pixel circuit according to claim 4 , wherein the second switching transistor and the third switching transistor are configured to interrupt the electrically conductive path between the source end of the driving transistor and the first voltage line when the second switching transistor is in the OFF state and/or the third switching transistor is in the OFF state.
7. The pixel circuit according to claim 1 , wherein, during the correction operation, the second switching transistor is in an ON state to cause the source end of the driving transistor to have a fixed voltage, and the third switching transistor is in an OFF state.
8. A display unit provided with a plurality of pixels and a driving circuit, the plurality of pixels each including a light-emitting device and a pixel circuit, the driving circuit being configured to drive the plurality of pixels, the pixel circuit comprising:
a driving transistor configured to control a current flowing in a light-emitting device;
a write transistor configured to control application of a signal voltage to a source end of the driving transistor, the signal voltage corresponding to an image signal;
a first switching transistor configured to control a gate voltage of the driving transistor upon correction operation that allows a gate-source voltage of the driving transistor to come close to a threshold voltage of the driving transistor;
a first storage capacitor provided at an electrically conductive path between a gate of the driving transistor and the source end of the driving transistor;
a second switching transistor and a third switching transistor disposed, in series, so as to selectively provide an electrically conductive path between the source end of the driving transistor and a first voltage line; and
a second storage capacitor provided at an electrically conductive path between the gate of the driving transistor and a node, the node coupling the second switching transistor and the third switching transistor.
9. The display unit according to claim 8 , wherein
the driving circuit outputs at least both a first voltage and a second voltage to the first voltage line,
the first voltage is outputted upon the correction operation, and
the second voltage is outputted upon the application of the signal voltage, and is higher than the first voltage.
10. The display unit according to claim 8 , wherein the pixel circuit further includes a fourth switching transistor disposed so as to selectively provide at an electrically conductive path between the source end of the driving transistor and the light-emitting device.
11. The display unit according to claim 8 , wherein the first switching transistor is diode-connected.
12. The display unit according to claim 8 , wherein, upon the correction operation, the driving circuit turns ON the first switching transistor to cause the gate of the driving transistor to have a first fixed voltage,
turns ON the second switching transistor and the third switching transistor to cause the source end of the driving transistor to have a second fixed voltage, and,
turns OFF the third switching transistor.
13. The display unit according to claim 8 , wherein the signal voltage is equal to or lower than a sum of a cathode voltage of the light-emitting device and a threshold voltage of the light-emitting device.
14. The display unit according to claim 8 , wherein the driving circuit applies a voltage corresponding to the signal voltage to the source end by turning ON the write transistor after performing the correction operation.
15. The display unit according to claim 8 , wherein
the second switching transistor is configured to switch between an ON state and an OFF state in response to a first control signal at a gate of the second switching transistor, and
the third switching transistor is configured to switch between an ON state and an OFF state in response to a second control signal at a gate of the third switching transistor.
16. The display unit according to claim 15 , wherein the second switching transistor and the third switching transistor are configured to provide the electrically conductive path between the source end of the driving transistor and the first voltage line when the second switching transistor is in the ON state and the third switching transistor is in the ON state.
17. The display unit according to claim 15 , wherein the second switching transistor and the third switching transistor are configured to interrupt the electrically conductive path between the source end of the driving transistor and the first voltage line when the second switching transistor is in the OFF state and/or the third switching transistor is in the OFF state.
18. A display unit provided with a plurality of pixels and a driving circuit, the plurality of pixels each including a light-emitting device and a pixel circuit, the driving circuit being configured to drive the plurality of pixels, the pixel circuit comprising:
a driving transistor configured to control a current flowing in a light-emitting device;
a write transistor configured to control application of a signal voltage to a source end of the driving transistor, the signal voltage corresponding to an image signal;
a first switching transistor configured to control a gate voltage of the driving transistor upon correction operation that allows a gate-source voltage of the driving transistor to come close to a threshold voltage of the driving transistor;
a first storage capacitor provided at an electrically conductive path between a gate of the driving transistor and the source end of the driving transistor;
a second switching transistor and a third switching transistor provided, in series, at an electrically conductive path between the source end of the driving transistor and a first voltage line; and
a second storage capacitor provided at an electrically conductive path between the gate of the driving transistor and a node, the node coupling the second switching transistor and the third switching transistor, wherein
the driving circuit outputs at least both a first voltage and a second voltage to the first voltage line,
the first voltage is outputted upon the correction operation, and
the second voltage is outputted upon the application of the signal voltage, and is higher than the first voltage.
19. The display unit according to claim 18 , wherein, upon the correction operation, the driving circuit turns ON the first switching transistor to cause the gate of the driving transistor to have a first fixed voltage,
turns ON the second switching transistor and the third switching transistor to cause the source end of the driving transistor to have a second fixed voltage, and,
turns OFF the third switching transistor.
20. The display unit according to claim 18 , wherein the signal voltage is equal to or lower than a sum of a cathode voltage of the light-emitting device and a threshold voltage of the light-emitting device.