Power supply circuit of an electro-optical device, driving circuit of an electro-optical device, method of driving an electro-optical device, electro-optical device, and electronic equipment

• US 6,633,287 B1
• Filed: 05/30/2000
• Issued: 10/14/2003
• Est. Priority Date: 06/01/1999
• Status: Expired due to Term

• Current Assignee: BOE Technology Group Co., Ltd.
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Yamazaki, Katsunori, Yatabe, Satoshi, Yamazaki, Suguru
• Primary Examiner(s): Saras, Steven
• Assistant Examiner(s): JORGENSEN, LELAND R
• Application Number:
  US09/580,599
• Time in Patent Office: 1,232 Days
• Field of Search: 345/76, 345/77, 345/78, 345/79, 345/80, 345/81, 345/87, 345/88, 345/89, 345/90, 345/91, 345/92, 345/93, 345/94, 345/95, 345/96, 345/97, 345/98, 345/99, 345/100, 345/101, 345/102, 345/103, 345/104, 345/211, 345/212, 345/213, 345/204, 345/205, 315/169.3
• US Class Current: 345/211
• CPC Class Codes: G09G 2320/041 Temperature compensation
• CPC Class Codes: G09G 2330/02 Details of power systems and of start or stop of display operation
• CPC Class Codes: G09G 3/367 with a nonlinear element in series with the liquid crystal cell, e.g. a diode, or M.I.M. element
• CPC Class Codes: G09G 3/3696 Generation of voltages supplied to electrode drivers
• CPC Class Codes: H02M 3/073 Charge pumps of the Schenkel-type

Abstract

A power supply circuit is provided for supplying a scanning line selection voltage to an electro-optical device. The electro-optical device includes pixels disposed at intersections between a plurality of scanning lines and a plurality of data lines, a voltage generation circuit for generating a selection voltage having a positive polarity (or a negative polarity) with respect to the center voltage of voltages applied to the data lines, a capacitor for storing the selection voltage, and an inverter circuit for inverting the polarity of the voltage stored in the capacitor with respect to the median voltage, and outputting the resultant voltage as a selection voltage having a negative polarity (or a positive polarity if the selection voltage has a negative polarity).

Claims

1. A power supply circuit that supplies a potential to an electro-optical device that includes a plurality of scanning lines and a plurality of data lines, said scanning lines crossing said data lines, and said potential serving as a selection voltage for selecting a scanning line from said plurality of scanning lines, said power supply circuit comprising:

a voltage generation circuit that generates one of a selection voltage having a positive polarity and a selection voltage having a negative polarity, defined with respect to a median value of signal voltages applied to said data lines;

a voltage storage element that stores a voltage based on said one selection voltage generated by said voltage generation circuit; and

an inverter circuit that inverts the polarity of the voltage stored in said voltage storage element with respect to a predetermined reference value, and that outputs the inverted voltage as another one of said selection voltage having a positive polarity and said selection voltage having a negative polarity,

said voltage generation circuit comprising;

a switching element; and

an inductor that stores electric power between a first input potential and a second input potential when said switching element turns on, and that releases the stored electric power when said switching element turns off,

using the electric power released from said inductor, said voltage generation circuit generating said one of the selection voltage having a positive potential and the selection voltage having a negative polarity with respect to the median value of signal voltages applied to said data lines, wherein the inverted voltage is a separately available output as another one of said selection voltage.

2. The power supply circuit, according to claim 1, said voltage generation circuit farther comprising a control circuit that controls a turning-on/off operation of said switching element in accordance with a comparison result of a voltage based on the electric power released from said inductor with respect to a target voltage.

3. The power supply circuit, according to claim 1, a turning-on/off operation of said switching element being controlled in response to a pulse signal.

4. The power supply circuit, according to claim 1, said inverter circuit comprising a voltage storage element having an electrode connected to a voltage terminal that is switched in response to a clock signal.

5. The power supply circuit, according to claim 1, when only a first area covered by some of said plurality of scanning lines is displayed and a second area covered by remaining scanning lines is not displayed, and when a scanning line in said second area is selected, polarity inversion by said inverter circuit not being performed or being performed at a reduced frequency.

6. A power supply circuit that supplies a potential to an electro-optical device that includes a plurality of scanning lines and a plurality of data lines, said scanning lines crossing said data lines, and said potential serving as a selection voltage for selecting a scanning line from said plurality of scanning lines, said power supply circuit comprising:

a voltage generation circuit that generates one of a selection voltage having a positive polarity and a selection voltage having a negative polarity, defined with respect to a median value of signal voltages applied to said data lines;

a voltage storage element that stores a voltage based on said one selection voltage generated by said voltage generation circuit; and

an inverter circuit that inverts the polarity of the voltage stored in said voltage storage element with respect to a predetermined reference value, and that outputs the inverted voltage as another one of said selection voltage having a positive polarity and said selection voltage having a negative polarity,

said voltage generation circuit comprising a transformer that inputs a pulse signal via a primary side of said transformer, and said voltage generation circuit generating said one of the selection voltage having a positive polarity and the selection voltage having a negative polarity using a voltage output from a secondary side of said transformer, wherein the inverted voltage is a separately available output as another one of said selection voltage.

7. The power supply circuit for an electro-optical device, according to claim 6, said transformer being a piezoelectric transformer that generates mechanical vibration in response to a voltage applied to the primary side of the transformer, that converts said mechanical vibration to a voltage, and that outputs the voltage resulting, from the secondary side.

8. The power supply circuit, according to claim 6, said voltage generation circuit further comprising a control circuit that controls a supply of said pulse signal to the primary side of said transformer in accordance with a comparison result of a voltage based on an output from the secondary side of said transformer with respect to a target voltage.

9. The power supply circuit, according to claim 6, said inverter circuit comprising a voltage storage element having an electrode connected to a voltage terminal that is switched in response to a clock signal.

10. The power supply circuit, according to claim 6, when only a first area covered by some of said plurality of scanning lines is displayed and a second area covered by remaining scanning lines is not displayed, and when a scanning line in said second area is selected, polarity inversion by said inverter circuit not being performed or being performed at a reduced frequency.

11. A driving circuit of an electro-optical device, that drives pixels disposed at intersections between a plurality of scanning lines and a plurality of data lines, said driving circuit comprising:

a power supply circuit that generates a selection voltage having a positive polarity and a selection voltage having a negative polarity, said positive polarity and said negative polarity being defined with respect to a median value of signal voltages applied to said data lines; and

a scanning line driving circuit that applies said selection voltage having a positive polarity and said selection voltage having a negative polarity, generated by said power supply circuit, to respective scanning lines in a predetermined order,

said power supply circuit comprising;

a voltage generation circuit that generates one of said selection voltages having a positive polarity and said selection voltage having a negative polarity, from a first input potential and a second input potential;

a voltage storage element that stores a voltage based on said one selection voltage generated by said voltage generation circuit; and

an inverter circuit that inverts the polarity of the voltage stored in said voltage storage element with respect to a predetermined reference value, and that outputs the inverted voltage as another one of said selection voltage having a positive polarity and said selection voltage having a negative polarity,

said voltage generation circuit comprising;

a switching element; and

an inductor that stores electric power between the first input potential and the second input potential when said switching element turns on, and that releases the stored electric power when said switching element turns off,

said voltage generation circuit generating said one of the selection voltage having a positive polarity and the selection voltage having a negative polarity using the electric power released from said inductor, wherein the inverted voltage is a separately available output as another one of said selection voltage.

12. A driving circuit of an electro-optical device, that drives pixels disposed at intersections between a plurality of scanning lines and a plurality of data lines, said driving circuit comprising:

a power supply circuit that generates a selection voltage having a positive polarity and a selection voltage having a negative polarity, said positive polarity and said negative polarity being defined with respect to a median value of signal voltages applied to said data lines; and

a scanning line driving circuit that applies said selection voltage having a positive polarity and said selection voltage having a negative polarity, generated by said power supply circuit, to respective scanning lines in a predetermined order,

said power supply circuit comprising;

a voltage generation circuit that generates one of said selection voltage having a positive polarity and said selection voltage having a negative polarity, from a first input potential and a second input potential;

a voltage storage element that stores a voltage based on said one selection voltage generated by said voltage generation circuit; and

an inverter circuit that inverts the polarity of the voltage stored in said voltage storage element with respect to a predetermined reference value, and that outputs the inverted voltage as another one of said selection voltage having a positive polarity and said selection voltage having a negative polarity,

said voltage generation circuit comprising a transformer that inputs a pulse signal via a primary side of said transformer, and said voltage generation circuit generating said one of the selection voltage having a positive polarity and the selection voltage having a negative polarity using a voltage output from a secondary side of said transformer, wherein the inverted voltage is a separately available output as another one of said selection voltage.

13. A method of driving an electro-optical device, for driving pixels disposed at intersections between a plurality of scanning lines and a plurality of data lines, said method comprising:

a first step of turning on and turning off a switching element such that, when said switching element is turned on, electric power is stored in an inductor between a first input potential and a second input potential, and when said switching element is turned off, the electric power stored in said inductor is released, thereby generating one of a selection voltage having a positive polarity and a selection voltage having a negative polarity with respect to a median value of signal voltages supplied to said data lines and thereby storing a voltage based on said one selection voltage; and

a second step of inverting the polarity of said voltage stored in said first step, with respect to a predetermined value, and outputting the inverted voltage as another one of said selection voltage having a positive polarity and said selection voltage having a negative polarity, selection voltages generated in said first and second steps being applied to respective scanning lines in a predetermined order, wherein the inverted voltage is a separately available output as another one of said selection voltage.

14. A method of driving an electro-optical device, for driving pixels disposed at intersections between a plurality of scanning lines and a plurality of data lines, said method comprising:

a first step of inputting a pulse signal to a primary side of a transformer, and generating, using a voltage output from a secondary side of said transformer, one of a selection voltage having a positive polarity and a selection voltage having a negative polarity with respect to a median value of signal voltages supplied to said data lines, and storing a voltage based on said one selection voltage; and

a second step of inverting the polarity of said voltage stored in said first step, with respect to a predetermined value, and outputting the inverted voltage as another one of said selection voltage having a positive polarity and said selection voltage having a negative polarity, selection voltages generated in said first step and said second step being applied to respective scanning lines in a predetermined order, wherein the inverted voltage is a separately available output as another one of said selection voltage.

15. An electro-optical device comprising:

pixels disposed at intersections between a plurality of scanning lines and a plurality of data lines;

a power supply circuit that generates a selection voltage having a positive polarity and a selection voltage having a negative polarity, said positive polarity and said negative polarity being defined with respect to a median value of signal voltages supplied to said data lines; and

a scanning line driving circuit that applies said selection voltage having a positive polarity and said selection voltage having a negative polarity, generated by said power supply circuit, to respective scanning lines in a predetermined order,

said power supply circuit comprising;

a voltage generation circuit that generates one of said selection voltage having a positive polarity and said selection voltage having a negative polarity, from a first input potential and a second input potential;

a voltage storage element that stores a voltage based on said one selection voltage generated by said voltage generation circuit; and

an inverter circuit that inverts the polarity of the voltage stored in said voltage storage element with respect to a predetermined reference value, and that outputs the inverted voltage as another one of said selection voltage having a positive polarity and said selection voltage having a negative polarity,

said voltage generation circuit comprising;

a switching element; and

an inductor that stores electric power between the first input potential and the second input potential when said switching element turns on, and that releases the stored electric power when said switching element turns off,

said voltage generation circuit generating said one of the selection voltage having the positive polarity and the selection voltage having a negative polarity using the electric power released from said inductor, wherein the inverted voltage is a separately available output as another one of said selection voltage.

16. An electronic equipment comprising the electro-optical device according to claim 15, said electro-optical device serving as a display unit.

17. An electro-optical device comprising:

pixels disposed at intersections between a plurality of scanning lines and a plurality of data lines;

a power supply circuit that generates a selection voltage having a positive polarity and a selection voltage having a negative polarity, said positive polarity and said negative polarity being defined with respect to a median value of signal voltages supplied to said data lines; and

a scanning line driving circuit that applies said selection voltage having a positive polarity and said selection voltage having a negative polarity, generated by said power supply circuit, to respective scanning lines in a predetermined order,

said power supply circuit comprising;

a voltage generation circuit that generates one of said selection voltages having a positive polarity and said selection voltage having a negative polarity, from a first input potential and a second input potential;

a voltage storage element that stores a voltage based on said one selection voltage generated by said voltage generation circuit; and

an inverter circuit that inverts the polarity of the voltage stored in said voltage storage element with respect to a predetermined reference value, and that outputs the inverted voltage as another one of said selection voltage having a positive polarity and said selection voltage having a negative polarity,

said voltage generation circuit comprising a transformer that inputs a pulse signal via a primary side of said transformer, and said voltage generation circuit generating said one of the selection voltage having a positive potential and the selection voltage having a negative polarity using a voltage output from a secondary side of said transformer, wherein the inverted voltage is a separately available output as another one of said selection voltage.

18. An electronic equipment comprising the electro-optical device according to claim 17, said electro-optical device serving as a display unit.

19. An electro-optical device comprising:

pixels disposed at intersections between a plurality of scanning lines and a plurality of data lines; and

a power supply circuit that generates a selection voltage having a positive polarity and a selection voltage having a negative polarity, said positive polarity and said negative polarity being defined with respect to a median value of signal voltages supplied to said data lines,

said power supply circuit comprising;

a voltage generation circuit that generates one of the selection voltage having a positive polarity and the selection voltage having a negative polarity from a first input potential and a second input potential using an inductor or a transformer driven in response to a pulse signal;

a voltage storage element that stores a voltage based on said one selection voltage generated by said voltage generation circuit; and

an inverter circuit that inverts the polarity of the voltage stored in said voltage storage element with respect to a predetermined reference value, and that outputs the inverted voltage as another one of said selection voltage having a positive polarity and said selection voltage having a negative polarity,

when only a first area covered by some of said plurality of scanning lines is displayed and a second area covered by remaining scanning lines is not displayed, and when a scanning line extending in said second area is selected, polarity inversion by said inverter circuit not being performed or being performed at a reduced frequency, wherein the inverted voltage is a separately available output as another one of said selection voltage.

20. An electronic equipment comprising the electro-optical device according to claim 19, said electro-optical device serving as a display unit.