Systems and methods for driving a display device

• US 6,822,631 B1
• Filed: 07/10/2001
• Issued: 11/23/2004
• Est. Priority Date: 11/19/1999
• Status: Expired due to Fees

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Yatabe, Satoshi
• Primary Examiner(s): LAO, LUN YI
• Application Number:
  US09/869,972
• Time in Patent Office: 1,232 Days
• Field of Search: 345/213, 345/204, 345/100, 345/89, 345/99, 345/94-96, 345/208, 345/210, 345/88, 345/209, 345/691, 345/692, 345/690
• US Class Current: 345/89
• CPC Class Codes: G09G 2320/0209 Crosstalk reduction, i.e. to reduce direct or indirect influences of signals directed to a certain pixel of the displayed image on other pixels of said image, inclusive of influences affecting pixels in different frames or fields or sub-images which constitute a same image, e.g. left and right images of a stereoscopic display
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 3/2014 by modulation of the duration of a single pulse during which the logic level remains constant
• 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

Abstract

In order to reduce power consumption in halftone display, each horizontal scanning period for which one of a plurality of scanning lines is selected is divided into first and second half periods. A nonselection voltage for bringing a TFD into a nonconductive state for the first half period and a selection voltage for bringing the TFD into a conductive state for the second half period are supplied as a scanning signal to the scanning line. When an odd scanning line is selected, a right shift modulation method is applied to the pixels located on the relevant scanning line; when an even scanning line is selected, a left shift modulation method is applied to the pixels located on the relevant scanning line. Thus a data signal Xi is supplied to the relevant data line. Since only one voltage switching of the data signal Xi per one horizontal scanning period is required for white or black display, and since only two voltage switchings are required for halftone display, the power consumption required for voltage switching is reduce.

Claims

1. A method of driving a display device so as to display a gray-scale image by driving pixels disposed at locations corresponding to respective intersections of a plurality of scanning lines extending along rows and a plurality of data lines extending along columns, said method comprising:

sequentially selecting said plurality of scanning lines one by one every horizontal scanning period;

applying a selection voltage to a selected scanning line during one of two half periods that said horizontal scanning period has been divided into; and

applying a voltage to a pixel such that;

in the case in which, of said plurality of scanning lines, a scanning line in either an odd-numbered or an even-numbered row is selected, a turn-on or a turn-off voltage is applied to a pixel at a location corresponding to an intersection of said scanning line and a data line belonging to a first group such that in one of said two half periods of each horizontal scanning period the turn-on voltage is applied via said data line to said pixel during a period from the start of one of the two half periods of the horizontal scanning period until a time corresponding to a gray level has elapsed, and the turn-off voltage is applied to said pixel during a remaining period of said one of the two half periods, while, in the case in which, of said plurality of scanning lines, a scanning line in the other one of odd-numbered and even-numbered rows is selected, the turn-on or the turn-off voltage is applied to the pixel at the location corresponding to the intersection of said scanning line and the data line belonging to the first group such that the turn-on voltage is applied via said data line to said pixel during a period from a point of time earlier than the end of said one of the half periods of the horizontal scanning period by an amount of time corresponding to a gray level until the end of said one of the two half periods, and the turn-off voltage is applied to said pixel during remaining period of said one of the two half periods, and

in either of these cases, in the other of said two half periods of said horizontal scanning period, the turn-on voltage is applied during a period equal to the period in which the turn-off voltage is applied in said one of the two half periods, while the turn-off voltage is applied during a period equal to the period in which the turn-on voltage is applied in said one of the two half periods.

2. The method of driving a display device according to claim 1, wherein the data lines belonging to said first group is all of said plurality of data lines.

3. The method of driving a display device according to claim 1, wherein in the case in which a scanning line in either an odd-numbered or an even-numbered row is selected, the turn-on or the turn-off voltage is applied to a pixel at a location corresponding to the intersection of said scanning line and a data line not belonging to the first group such that:

in one of said two half periods of each horizontal scanning period, the turn-on voltage is applied via said data line to the pixel during a period from a point of time earlier than the end of said one of the two half periods of the horizontal scanning period by an amount of time corresponding to a gray level until the end of said one of the two half period, and the turn-off voltage is applied to said pixel during the remaining period of said one of the two half periods, while, in the case in which a scanning line in the other one of odd-numbered and even-numbered rows is selected, the turn-on or the turn-off voltage is applied to the pixel at the location corresponding to the intersection of said scanning line and the data line not belonging to the first group such that the turn-on voltage is applied via said data line to said pixel during a period from the start of one of the two half periods of the horizontal scanning period until a time corresponding to a gray level has elapsed, and the turn-off voltage is applied to said pixel during the remaining period of said one of the half periods, and

in either of these cases, in the other of said two half periods of said horizontal scanning period, the turn-on voltage is applied during a period equal to the period in which the turn-off voltage is applied in said one of the two half periods, while the turn-off voltage is applied during a period equal to the period in which the turn-on voltage is applied in said one of the two half periods.

4. The method of driving a display device according to claim 1, wherein the number of data lines belonging to said first group is equal to or substantially equal to the number of data lines not belonging to said first group.

5. The method of driving a display device according to claim 4, wherein the data lines belonging to said first group are those data lines, of said plurality of data lines, located in either odd-numbered columns or even-numbered columns.

6. A driver circuit for driving a display device so as to display a gray-scale image by driving pixels disposed at locations corresponding to respective intersections of a plurality of scanning lines extending along rows and a plurality of data lines extending along columns, said driver circuit comprising:

a scanning line driver circuit that;

sequentially select said plurality of scanning lines one by one every horizontal scanning period, and

applies a selection voltage to a selected scanning line during one of two half periods that said horizontal scanning period has been divided into; and

a data line driver circuit that applies a voltage to a pixel such that;

in the case in which, of said plurality of scanning lines, a scanning line in either an odd-numbered or an even-numbered row is selected, a turn-on or a turn-off voltage is applied to a pixel at a location corresponding to an intersection of said scanning line and a data line belonging to a first group, such that in one of said half periods of each horizontal scanning period, the turn-on voltage is applied via said data line to said pixel during a period from the start of one of the two half periods of the horizontal scanning period until a time corresponding to a gray level has elapsed, and the turn-off voltage is applied to said pixel during the remaining period of said one of the two half periods, while, in the case in which, of said plurality of scanning lines, a scanning line in the other one of odd-numbered and even-numbered rows is selected, the turn-on or the turn-off voltage is applied to the pixel at the location corresponding to the intersection of said scanning line and the data line belonging to the first group such that the turn-on voltage is applied via said data line to said pixel during a period from a point of time earlier than the end of said one of the two half periods of the horizontal scanning period by an amount of time corresponding to a gray level until the end of said one of the two half periods, and the turn-off voltage is applied to said pixel during the remaining period of said one of the half periods, and

in either of these cases, in the other of said half periods of said horizontal scanning period, the turn-on voltage is applied during a period equal to the period in which the turn-off voltage is applied in said one of the two half periods, while the turn-off voltage is applied during a period equal to the period in which the turn-on voltage is applied in said one of the two half periods.

7. A display device comprising a pair of substrates, an electrooptical material disposed between said pair of substrates, a plurality of scanning lines formed on one of said pair of substrates, a plurality of data lines formed on the other one of said pair of substrates, and pixels disposed at locations corresponding to intersections of said plurality of scanning lines and said plurality of data lines, said display device serving to display a gray-scale image by driving said pixels, said display device further comprising:

a scanning line driver circuit that;

sequentially selects said plurality of scanning lines one by one every horizontal scanning period, and

applies a selection voltage to a selected scanning line during one of two half periods that said horizontal scanning period has been divided into; and

a data line driving circuit that applies a voltage to a pixel such that;

in the case in which, of said plurality of scanning lines, a scanning line in either an odd-numbered or an even-numbered row is selected, a turn-on or a turn-off voltage is applied to a pixel at a location corresponding to an intersection of said scanning line and a data line belonging to a first group, such that in one of said half periods of each horizontal scanning period, the turn-on voltage is applied via said data line to said pixel during a period from the start of one of the two half periods of the horizontal scanning period until a time corresponding to a gray level has elapsed, and the turn-off voltage is applied to said pixel during the remaining period of said one of the two half periods, while, in the case in which, of said plurality of scanning lines, a scanning line in the other one of odd-numbered and even-numbered rows is selected, the turn-on or the turn-off voltage is applied to the pixel at the location corresponding to the intersection of said scanning line and the data line belonging to the first group such that the turn-on voltage is applied via said data line to said pixel during a period from a point of time earlier than the end of said one of the two half periods of the horizontal scanning period by an amount of time corresponding to a gray level until the end of said one of the two half period, and the turn-off voltage is applied to said pixel during the remaining period of said one of the two half periods, and

in either of these cases, in the other of said two half periods of said horizontal scanning period, the turn-on voltage is applied during a period equal to the period in which the turn-off voltage is applied in said one of the two half periods, while the turnoff voltage is applied during a period equal to the period in which the turn-on voltage is applied in said one of the two half periods.

8. The display device according to claim 7, wherein:

said pixel includes a switching element and a capacitor formed of said electrooptical material; and

said capacitor is driven by said switching element.

9. The display device according to claim 8, wherein said switching element is a thin film diode having a conductor/insulation/conductor structure, one end of said thin film diode being connected to either said scanning line or said data line and the other end being connected to said capacitor.

10. An electronic device including a display device according to claim 7.