Power supply circuit, voltage conversion circuit, semiconductor device, display device, display panel, and electronic equipment

• US 20050052447A1
• Filed: 09/28/2004
• Published: 03/10/2005
• Est. Priority Date: 09/14/2001
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Ishiyama, Hisanobu
• Granted Patent: US 7,205,990 B2
• Time in Patent Office: Days
• US Class Current: 345/211
• CPC Class Codes: G09G 2320/0276 for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction
• CPC Class Codes: G09G 2330/02 Details of power systems and of start or stop of display operation
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence
• CPC Class Codes: G09G 3/3688 suitable for active matrices only

Abstract

A power supply circuit which generates a power supply for a circuit which drives a source electrode and a gate electrode provided in a display, includes a first booster circuit which outputs a third potential boosted based on a difference between first and second potentials, a potential regulator circuit which outputs a fourth potential being a constant potential generated based on a difference between the first and third potentials, and a second booster circuit which outputs a fifth potential boosted based on a difference between the first and fourth potentials. The first and fourth potentials are supplied to a source electrode driver circuit, and the first and fifth potentials are supplied to a gate electrode driver circuit. A voltage supplied to the gate electrode driver circuit may be generated by using a voltage conversion circuit. The voltage conversion circuit includes a capacitor which capacitively couples a sixth power supply line to which a negative constant potential based on a first potential is supplied and a node to which a polarity inversion timing signal of a common electrode is supplied, a negative power supply generating circuit which generates a negative output potential based on a booster potential which is the difference between a regulating potential and the first potential, and a switching element connected between the negative power supply generating circuit and the sixth power supply line. A timing signal and a switching control signal of the switching element change in synchronization with each other.

Claims

1. A voltage conversion circuit which generates an output potential that is negative based on a first potential, comprising:

a capacitor which capacitively couples a node to which a timing signal changing between given potentials is supplied and an output power supply line to which the output potential is supplied;

a negative power supply generating circuit which generates a negative potential based on the first potential based on a difference between the first potential and an input potential which is positive based on the first potential; and

a switching element which is inserted between a node to which the negative power supply potential is supplied and the output power supply line, and controlled based on a given switching control signal,

wherein the timing signal and the switching control signal change in synchronization with each other.

2. The voltage conversion circuit as defined in claim 1,

wherein the switching element is an n-type switching transistor,

wherein the negative power supply generating circuit comprises:

a p-type transistor, a source terminal of which is connected with the first potential;

a first capacitor which capacitively couples a first node to which a first booster clock is supplied and a gate terminal of the p-type transistor;

a first level shifter which is connected between the source terminal of the p-type transistor and the gate terminal of the p-type transistor;

an n-type transistor, a drain terminal of which is connected with a drain terminal of the p-type transistor, and a source terminal of which is connected with a second node;

a second capacitor which capacitively couples the first potential and the second node;

a third capacitor which capacitively couples a third node to which a second booster clock is supplied and a gate terminal of the n-type transistor;

a second level shifter which is connected between the source terminal of the n-type transistor and the gate terminal of the n-type transistor; and

a fourth capacitor which capacitively couples a fourth node to which a given potential is supplied and the drain terminal of the n-type transistor,

wherein the first booster clock falls after the second booster clock has fallen, and the second booster clock rises after the first booster clock has risen,

wherein the potential supplied to the fourth node changes to the input potential in synchronization with fall of the first booster clock, and changes to the first potential in synchronization with rise of the second booster clock, and

wherein the source terminal of the n-type transistor is connected with the output power supply line through the n-type switching transistor.

3. A display device comprising:

a power supply circuit which includes;

a first booster circuit which is connected with first and second power supply lines, which respectively supply first and second potentials, and supplies a third potential which is boosted based on a difference between the first and second potentials to a third power supply line;

a potential regulator circuit which is connected with the first and third power supply lines and supplies a fourth potential, which is a constant potential generated based on a difference between the first and third potentials, to a fourth power supply line; and

a second booster circuit which is connected with the first and fourth power supply lines and supplies a fifth potential, which is boosted based on a difference between the first and fourth potentials, to a fifth power supply line;

a display which includes a plurality of source electrodes and a plurality of gate electrodes;

the voltage conversion circuit as defined in claim 1 with which the first power supply line, to which the first potential is supplied, and the fifth power supply line, to which the fifth potential is supplied as the input potential, are connected;

a source electrode driver circuit with which at least the fourth power supply line is connected and which drives the plurality of source electrodes; and

a gate electrode driver circuit with which at least the fifth power supply line and the output power supply line, to which the output potential generated by the voltage conversion circuit is supplied, are connected.

4. Electronic equipment comprising the voltage conversion circuit as defined in claim 1.

5. Electronic equipment comprising:

a power supply circuit which includes;

a first booster circuit which is connected with first and second power supply lines, which respectively supply first and second potentials, and supplies a third potential which is boosted based on a difference between the first and second potentials to a third power supply line;

a potential regulator circuit which is connected with the first and third power supply lines and supplies a fourth potential, which is a constant potential generated based on a difference between the first and third potentials, to a fourth power supply line; and

a second booster circuit which is connected with the first and fourth power supply lines and supplies a fifth potential, which is boosted based on a difference between the first and fourth potentials, to a fifth power supply line; and

the voltage conversion circuit as defined in claim 1 with which the first and fifth power supply lines are connected,

wherein the fifth potential supplied to the fifth power supply line is used as an input potential to the voltage conversion circuit.

6. Electronic equipment comprising the display device as defined in claim 3.