Driver, electro-optical device, and electronic device

Patent metadata

Field	Value
Publication number	US-9570033-B2
Application number	US-201514669943-A
Country	US
Kind code	B2
Filing date	Mar 26, 2015
Priority date	Mar 27, 2014
Publication date	Feb 14, 2017
Grant date	Feb 14, 2017

Abstract

A driver, an electro-optical device, and an electronic device are provided with which a rise in a ground line voltage due to a discharge can be suppressed. The driver includes a voltage generating circuit 100 that generates a first voltage VA 1 and a second voltage VA 2 for driving a display panel, outputs the first voltage VA 1 to a first node NA 1 , and outputs the second voltage VA 2 to a second node NA 2 , and a discharge circuit 140 that performs a discharge operation if the voltage generating circuit 100 is deactivated. The discharge circuit 140 performs a first discharge operation of discharging the first node NA 1 , and thereafter performs a second discharge operation of discharging the second node NA 2.

First claim

What is claimed is:

1. A driver comprising:
a voltage generating circuit that generates a first voltage and a second voltage for driving a display panel, outputs the first voltage to a first node, and outputs the second voltage to a second node; and
a discharge circuit that performs a discharge operation if the voltage generating circuit is deactivated,
the discharge circuit performing a first discharge operation of discharging the first node, and thereafter performing a second discharge operation of discharging the second node, and
the order of discharge being based on values of the first voltage and the second voltage, such that the first node and the second node are discharged in ascending order of the values of the first voltage and the second voltage.

2. The driver according to claim 1 ,
wherein the voltage generating circuit comprises a first voltage drop circuit that drops the second voltage to generate the first voltage.

3. The driver according to claim 2 ,
wherein the voltage generating circuit comprises a booster circuit that boosts a system power supply voltage to generate the second voltage, and
the first voltage drop circuit generates a common voltage of the display panel as the first voltage obtained by dropping the second voltage.

4. The driver according to claim 2 ,
wherein the voltage generating circuit comprises a second voltage drop circuit that drops the first voltage to generate a third voltage, and outputs the third voltage to a third node, and
the discharge circuit performs a third discharge operation of discharging the third node, and thereafter performs the first discharge operation.

5. The driver according to claim 4 ,
wherein the second voltage drop circuit generates a segment voltage of the display panel as the third voltage.

6. The driver according to claim 4 , further comprising:
a control circuit that controls the discharge circuit,
wherein the discharge circuit comprises first to third switching circuits that are provided between a node of a ground line voltage and the first to third nodes, respectively, and
by the control circuit turning on the third switching circuit, the first switching circuit, and the second switching circuit in this order, the discharge circuit performs the third discharge operation, the first discharge operation, and the second discharge operation in this order.

7. The driver according to claim 4 , further comprising:
first to third output terminals for connecting first to third external capacitors,
wherein the first to third nodes are connected to the first to third output terminals.

8. The driver according to claim 1 , further comprising:
a drive circuit that drives the display panel based on at least the first voltage among the first voltage and the second voltage,
wherein, after the drive circuit ends the driving of the display panel, the voltage generating circuit is deactivated, and the discharge circuit performs the discharge operation.

9. An electro-optical device comprising:
the driver according to claim 1 ; and
the display panel.

10. The electro-optical device according to claim 9 ,
wherein a ground terminal of the electro-optical device and a ground terminal of the driver are connected to each other by an interconnect of a transparent electrode of the display panel.

11. An electronic device comprising: the driver according to claim 1 .

12. The driver according to claim 1 ,
wherein the discharge circuit performs the first discharge operation by discharging charges stored in the first node to a ground line voltage, and thereafter performs the second discharge operation by discharging charges stored in the second node to the ground line voltage.

13. A driver comprising:
a voltage generating circuit that generates a first voltage and a second voltage for driving a display panel, outputs the first voltage to a first node, and outputs the second voltage to a second node;
a drive circuit that drives the display panel based on at least one of the first voltage and the second voltage; and
a discharge circuit that, after the drive circuit ends driving the display panel and the voltage generating circuit is deactivated, discharges the first node, and then discharges the second node, and
the order of discharge being based on values of the first voltage and the second voltage, such that the first node and the second node are discharged in ascending order of the values of the first voltage and the second voltage.

14. The driver according to claim 13 ,
wherein the voltage generating circuit comprises a first voltage drop circuit that drops the second voltage to generate the first voltage.

15. The driver according to claim 14 , wherein
the voltage generating circuit comprises a booster circuit that boosts a system power supply voltage to generate the second voltage, and
the first voltage drop circuit generates a common voltage of the display panel as the first voltage obtained by dropping the second voltage.

16. The driver according to claim 14 , wherein
the voltage generating circuit comprises a second voltage drop circuit that drops the first voltage to generate a third voltage, and outputs the third voltage to a third node, and
the discharge circuit discharges the third node, and then discharges the first node.

17. The driver according to claim 16 ,
wherein the second voltage drop circuit generates a segment voltage of the display panel as the third voltage.

18. The driver according to claim 16 , further comprising:
a control circuit that controls the discharge circuit,
wherein the discharge circuit comprises first to third switching circuits that are provided between a node of a ground line voltage and each of the first, second and third nodes, respectively, and
by the control circuit turning on the third switching circuit, the first switching circuit, and the second switching circuit in this order, the discharge circuit discharges the third node, the first node, and the second node in this order.

19. The driver according to claim 16 , further comprising:
first, second and third output terminals for connecting first, second and third external capacitors,
wherein the first, second and third nodes are connected to the first, second and third output terminals.

Assignees

• Seiko Epson Corp

Inventors

• Muraki Norichika

Classifications

• G06F3/147

  using display panels · CPC title

• G09G3/3622

  using a passive matrix (G09G3/3674 - G09G3/3696 take precedence) · CPC title

• G09G2310/08

  Details of timing specific for flat panels, other than clock recovery · CPC title

• G09G2310/0278

  Details of driving circuits arranged to drive both scan and data electrodes · CPC title

• G09G2330/027

  Arrangements or methods related to powering off a display · CPC title