Electro-optical device, driving circuit of electro-optical device, and electronic apparatus

• US 20060158395A1
• Filed: 01/03/2006
• Published: 07/20/2006
• Est. Priority Date: 01/19/2005
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Fujikawa, Shinsuke, Kubota, Takehiko
• Granted Patent: US 7,633,480 B2
• Time in Patent Office: Days
• US Class Current: 345/76
• CPC Class Codes: G09G 2320/0257 Reduction of after-image effects
• CPC Class Codes: G09G 3/3258 with pixel circuitry controlling the voltage across the light-emitting element
• CPC Class Codes: G09G 3/3291 in which the data driver supplies a variable data voltage for setting the current through, or the voltage across, the light-emitting elements

Abstract

A driving circuit drives an electro-optical device in which a gray-scale level of each of a plurality of electro-optical elements provided so as to correspond to a plurality of data lines is controlled on the basis of a voltage of a corresponding data line. The driving circuit includes a pulse output circuit that outputs a plurality of sampling pulses, each of the plurality of sampling pulses becoming an active level sequentially; a plurality of unit circuits each of which is supplied with a sampling pulse from the pulse output circuit; and a signal line that is supplied with a gray-scale signal to sequentially designate a gray-scale level of each of the electro-optical elements. Each of the plurality of unit circuits has a first switching element that samples the gray-scale signal supplied to the signal line in accordance with a sampling pulse output from the pulse output circuit; a second switching element that is inserted between the first switching element and the data line and enters an off state until a predetermined period passes from a time when sampling operation is started by the first switching element; and a storage capacitor that holds a voltage of an output terminal of the second switching element.

Claims

1. A driving circuit that drives an electro-optical device in which a gray-scale level of each of a plurality of electro-optical elements that correspond to a plurality of data lines is controlled on a basis of a voltage of a corresponding data line, the driving circuit comprising:

a pulse output circuit that outputs a plurality of sampling pulses, each of the plurality of sampling pulses becoming an active level sequentially;

a plurality of unit circuits each of which is supplied with a sampling pulse from the pulse output circuit;

a signal line that is supplied with a gray-scale signal to sequentially designate a gray-scale level of each of the electro-optical elements;

each of the plurality of unit circuits, further including;

a first switching element that samples the gray-scale signal supplied to the signal line in accordance with a sampling pulse output from the pulse output circuit;

a second switching element that is inserted between the first switching element and the data line and that enters an off state until a predetermined period passes from a time when the first switching element starts a sampling operation; and

a storage capacitor that holds a voltage of an output terminal of the second switching element.

2. The driving circuit according to claim 1,

the storage capacitor being a capacitor element, a first end of which is connected to the output terminal of the second switching element.

3. The driving circuit according to claim 2, further comprising:

first and second potential supply lines, each of which is supplied with an individual potential;

a smoothing capacitor that is arranged between the first potential supply line and the second potential supply line; and

a second end of the storage capacitor being coupled with an end of the smoothing capacitor.

4. The driving circuit according to claim 3, further comprising:

an output buffer that is arranged between the second switching element and the data line; and

the first and second potential supply lines being wiring lines that supply a power supply potential to the output buffer.

5. The driving circuit according to claim 1,

the pulse output circuit, including:

a shift register that sequentially generates a plurality of pulse signals, such that a period for which one pulse signal becomes an active level overlaps a period for which another pulse signal, that is subsequent to the one pulse signal, becomes an active level;

logical product circuits, each of which outputs a logical product between one pulse signal and another pulse signal, subsequent to the one pulse signal, as a sampling pulse; and

the second switching element of each unit circuit being controlled to be turned on or turned off based on a pulse signal output from the shift register.

6. The driving circuit according to claim 1,

each unit circuit having a logical sum circuit that outputs a signal corresponding to a logical sum between a sampling pulse input to the corresponding unit circuit and a sampling pulse input to a unit circuit located at a front stage of the corresponding unit circuit;

and

the second switching element being controlled so as to be turned on or turned off based on a signal output from the logical sum circuit.

7. The driving circuit according to claim 1,

each unit circuit having a delay element that is arranged between the signal line and the first switching element;

and

the second switching element of each unit circuit being controlled so as to be turned on or turned off based on a sampling pulse output from the pulse output circuit.

8. The driving circuit according to claim 1,

the second switching element being a transmission gate.

9. The driving circuit according to claim 1,

the second switching element being a clocked inverter having an output terminal that enters a high impedance state in an off state and that serves as an inverter in an on state.

10. An electro-optical device, comprising:

a plurality of electro-optical elements that correspond to a plurality of data lines, each having a gray-scale level based on a voltage of a corresponding data line;

a pulse output circuit that outputs a plurality of sampling pulses, each of the plurality of sampling pulses becoming an active level sequentially;

a plurality of unit circuits each of which is supplied with a sampling pulse output from the pulse output circuit;

a signal line that is supplied with a gray-scale signal to sequentially designate a gray-scale level of each of the electro-optical elements;

each of the plurality of unit circuits, further including;

a first switching element that samples the gray-scale signal supplied to the signal line in accordance with a sampling pulse output from the pulse output circuit;

a second switching element that is inserted between the first switching element and the data line and that enters an off state until a predetermined period passes from a time when the first switching element starts a sampling operation; and

a storage capacitor that holds a voltage of an output terminal of the second switching element.

11. The electro-optical device according to claim 10,

the electro-optical element being arranged between a first power supply line having a first potential and a second power supply line having a second potential that is different from the first potential;

and

the storage capacitor, further including;

a first capacitor element that has a first end coupled with an output terminal of the second switching element and has a second end coupled with the first power supply line; and

a second capacitor element that has a first end coupled with an output terminal of the second switching element and has a second end coupled with the second power supply line.

12. The electro-optical device according to claim 10, further comprising:

a plurality of pixel circuits, each including the electro-optical element;

each of the plurality of pixel circuits having a transistor that controls a voltage applied to the electro-optical element based on a voltage applied to a gate electrode through a corresponding data line; and

the storage capacitor being a gate capacitor of the transistor.

13. An electronic apparatus, comprising:

the electro-optical device according to claim 10.