ELECTRO-OPTICAL DEVICE, METHOD FOR DRIVING ELECTRO-OPTICAL DEVICE, AND ELECTRONIC APPARATUS

• US 20080042942A1
• Filed: 04/11/2007
• Published: 02/21/2008
• Est. Priority Date: 04/19/2006
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: TAKAHASHI, Kasori
• Granted Patent: US 8,125,419 B2
• Time in Patent Office: Days
• US Class Current: 345/77
• CPC Class Codes: G09G 2300/0439 Pixel structures
• CPC Class Codes: G09G 3/207 by domain size control G09G3/3637 takes precedence
• 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

An electro-optical device includes a unit circuit and a signal generating circuit. The unit circuit includes a first element section that controls a first electro-optical element to a gradation level corresponding to a level of a data signal, and a second element section that controls a second electro-optical element to a gradation level corresponding to a level of a data signal. When data signals having an identical level are applied to the first element section and the second element section, the gradation level of the first electro-optical element is lower than the gradation level of the second electro-optical element. The signal generating circuit generates data signals having different levels according to a gradation value specified for the unit circuit. When the gradation value is within a first gradation range, the signal generating circuit applies to the first element section a data signal whose level is determined so that the first electro-optical element is controlled to a gradation level corresponding to the gradation value. When the gradation value is within a second gradation range higher than the first gradation range, the signal generating circuit applies to the second element section a data signal whose level is determined so that the second electro-optical element is controlled to a gradation level corresponding to the gradation value.

Claims

1. An electro-optical device comprising:

a unit circuit including

a first element section that controls a first, electro-optical element to a gradation level corresponding to a level of a data signal, and

a second element section that controls a second electro-optical element to a gradation level corresponding to a level of a data signal,

the gradation level of the first electro-optical element being lower than the gradation level of the second electro-optical element when data signals having an identical level are applied to the first element section and the second element section; and

a signal generating circuit that generates data signals having different levels according to a gradation value specified for the unit circuit,

wherein when the gradation value is within a first gradation range, the signal generating circuit applies to the first element section a data signal whose level is determined so that the first electro-optical element is controlled to a gradation level corresponding to the gradation value, and

when the gradation value is within a second gradation range higher than the first gradation range, the signal generating circuit applies to the second element section a data signal whose level is determined so that the second electro-optical element is controlled to a gradation level corresponding to the gradation value.

2. The electro-optical device according to claim 1, wherein the area of a region of the first electro-optical element from which light is output is different from the area of a region of the second electro-optical element from which light is output.

3. The electro-optical device according to claim 1, wherein each of the first electro-optical element and the second electro-optical element is a light-emitting element including a first electrode, a second electrode, and a light-emitting layer between the first electrode and the second electrode, and

a distance between the first electrode and the second electrode of the first electro-optical element is different from a distance between the first electrode and the second electrode of the second electro-optical element.

4. The electro-optical device according to claim 1, wherein each of the first electro-optical element and the second electro-optical element is a light-emitting element including a first optically transparent electrode, a second optically reflective electrode facing the first electrode, and a light-emitting layer between the first electrode and the second electrode, and

the first electrode of the first electro-optical element and the first electrode of the second electro-optical element have different thicknesses.

5. The electro-optical device according to claim 1, further comprising an optically transparent insulation layer defined on a surface of a substrate,

wherein each of the first electro-optical element and the second electro-optical element is a light-emitting element including a first optically transparent electrode defined on a surface of the insulation layer, a second optically reflective electrode facing the first electrode, and a light-emitting layer between the first electrode and the second electrode, and

the thickness of a region of the insulation layer through which light output from the first electro-optical element is transmitted is different from the thickness of a region of the insulation layer through which light output from the second electro-optical element is transmitted.

6. The electro-optical device according to claim 1, further comprising:

a first light-transmitting member through which light output from the first electro-optical element is transmitted; and

a second light-transmitting member through which light output from the second electro-optical element is transmitted,

wherein the first light-transmitting member and the second light-transmitting member have different transmittances.

7. The electro-optical device according to claim 1, wherein:

the first element section includes a first driving transistor that generates a drive current corresponding to a voltage at a gate of the first driving transistor and that supplies the drive current to the first electro-optical element;

the second element section includes a second driving transistor that generates a drive current corresponding to a voltage at a gate of the second driving transistor and that supplies the drive current to the second electro-optical element; and

the drive current generated by the first driving transistor and the drive current generated by the second driving transistor have different, current values when the same voltage is applied to the gate of the first driving transistor and the gate of the second driving transistor.

8. The electro-optical device according to claim 1, wherein the first element section controls the first electro-optical element to emit light at a brightness corresponding to the level of the data signal in a first period, and

the second element section controls the second electro-optical element to emit light at a brightness corresponding to the level of the data signal in a second period longer than the first period.

9. The electro-optical device according to claim 1, wherein:

the first element section controls the first electro-optical element to a gradation level corresponding to a voltage value of the data signal;

the second element section controls the second electro-optical element to a gradation level corresponding to a current value of the data signal; and

the signal generating circuit includes

a voltage generating circuit that outputs a data signal having a voltage value corresponding to the gradation value specified for the unit circuit to the first element section when the gradation value is within the first gradation range, and

a current generating circuit that supplies a data signal having a current value corresponding to the gradation value to the second element section when the gradation value is within the second gradation range.

10. An electronic apparatus comprising the electro-optical device according to claim 1.

11. A method for driving an electro-optical device including a unit circuit including a first element section that controls a first electro-optical element to a gradation level corresponding to a level of a data signal, and a second element section that controls a second electro-optical element to a gradation level corresponding to a level of a data signal, the gradation level of the first electro-optical element being lower than the gradation level of the second electro-optical element when data signals having an identical level are applied to the first element section and the second element section;

and, the method comprising;

determining which of a plurality of gradation ranges including a first gradation range and a second gradation range higher than the first gradation range a gradation value specified for the unit circuit belongs to; and

generating data signals having different levels according to the gradation value,

wherein when it is determined that the gradation value is within the first gradation range, a data signal whose level is determined so that the first electro-optical element is controlled to a gradation level corresponding to the gradation value is applied to the first element section, and

when it is determined that the gradation value is within the second gradation range, a data signal whose level is determined so that the second electro-optical element is controlled to a gradation level corresponding to the gradation value is applied to the second element section.