Electrooptic device using an area scanning drive system and a method for driving the same

• US 8,031,161 B2
• Filed: 08/17/2007
• Issued: 10/04/2011
• Est. Priority Date: 09/29/2006
• Status: Expired due to Fees

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Ishii, Kenya
• Primary Examiner(s): Nguyen; Chanh
• Assistant Examiner(s): Yang; Kwang-Su
• Application Number:
  US11/840,642
• Publication Number:
  US 20080079710A1
• Time in Patent Office: 1,509 Days
• Field of Search: 345/94, 345/96, 345/99, 345/100, 345/103, 345/214
• US Class Current: 345/100
• CPC Class Codes: G09G 2300/08 Active matrix structure, i.e. with use of active elements, inclusive of non-linear two terminal elements, in the pixels together with light emitting or modulating elements
• CPC Class Codes: G09G 2310/0251 Precharge or discharge of pixel before applying new pixel voltage
• CPC Class Codes: G09G 2310/0256 with the purpose of reversing the voltage across a light emitting or modulating element within a pixel
• CPC Class Codes: G09G 2310/0267 Details of drivers for scan electrodes, other than drivers for liquid crystal, plasma or OLED displays
• CPC Class Codes: G09G 2310/0275 Details of drivers for data electrodes, other than drivers for liquid crystal, plasma or OLED displays, not related to handling digital grey scale data or to communication of data to the pixels by means of a current
• CPC Class Codes: G09G 3/001 using specific devices not provided for in groups G09G3/02 - G09G3/36, e.g. using an intermediate record carrier such as a film slide; Projection systems; Display of non-alphanumerical information, solely or in combination with alphanumerical information, e.g. digital display on projected diapositive as background slide projectors per se G03B23/00 = 42 HP
• CPC Class Codes: G09G 3/2096 Details of the interface to the display terminal specific for a flat panel suitable for both CRT and flat panel G09G5/006; specific for a CRT G09G1/167
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence
• CPC Class Codes: G09G 3/3677 suitable for active matrices only

Abstract

An electrooptic device includes 1) row groups of pixels that are made black during successive first precharge periods that are next to row groups of pixels to which a voltage corresponding to the gray level is written during successive first writing periods, 2) row groups of pixels that are made black during successive second precharge periods that are next to row groups of pixels to which a voltage corresponding to the gray level is written during successive second writing periods, and 3) row groups of pixels that are made black during successive first precharge periods that are next to row groups of pixels that are made black during successive second precharge periods.

Claims

1. A method for driving an electrooptic device having pixels disposed in correspondence with the intersections of a plurality of rows of scanning lines and a plurality of columns of data lines, each pixel producing a gray level corresponding to a data signal applied to a corresponding data line when a selecting voltage is applied to a corresponding scanning line, the method comprising:

assigning four rows of scanning lines that are separated from each other by a predetermined number of rows of scanning lines, to a first precharge period, a first writing period, a second precharge period, and a second writing period, the writing periods having a longer duration than the precharge periods, and the precharge signal being applied simultaneously to the plurality of data lines, respectively;

sequentially assigning rows in subsequent sets of four rows to the first precharge period, the first writing period, the second precharge period, and the second writing period, respectively, the rows in each subsequent set of four rows being shifted one row each from rows of a preceding set of four rows, rows assigned to a same one of the first precharge period, the first writing period, the second precharge period, and the second writing period forming a row group,

during the first precharge period, applying the selecting voltage to an assigned scanning line and providing a first data signal to the data lines, the first precharge data signal having a precharge voltage that makes the pixel black and having a polarity that is one of higher and lower than a predetermined reference voltage;

during the first writing period, applying the selecting voltage to an assigned scanning line and providing a first writing data signal to the data lines, the first writing data signal having a voltage corresponding to the gray level of the pixel and having a polarity that is one of higher and lower than the reference voltage;

during the second precharge period, applying the selecting voltage to an assigned scanning line and providing a second precharge data signal to the data lines, the second precharge data signal having a precharge voltage that makes the pixel black and having a polarity that is the other of higher and lower than the reference voltage; and

during the second writing period, applying the selecting voltage to an assigned scanning line and providing a second writing data signal to the data lines, the second writing data signal having a voltage corresponding to the gray level of the pixel and having a polarity that is the other of higher and lower than the reference voltage;

the row group of the first precharge period is next to the row group of the first writing period;

the row group of the second precharge period is next to the row group of the second writing period;

the row group of the first precharge period is remote from the row group of the second precharge period; and

the first and second precharge data signals and the first and second writing data signals are each assigned to first to fourth enable signals during a first clock period, and during a second clock period, the first and second precharge data signals and the first and second writing data signals assigned to the first to fourth enable signals are shifted.

2. The method according to claim 1, wherein:

the first writing period is started after the end of the first precharge period; and

the second writing period is started after the end of the second precharge period.

3. The method according to claim 1, wherein:

the termination of the first precharge period and the beginning of the first writing period overlap; and

the termination of the second precharge period and the beginning of the second writing period overlap.

4. An electrooptic device comprising:

pixels disposed in correspondence with the intersections of a plurality of rows of scanning lines and a plurality of columns of data lines, each pixel producing a gray level corresponding to a data signal applied to the data lines when a predetermined selecting voltage is applied to a scanning line corresponding to the pixel itself;

a data-line driving circuit that writes a voltage corresponding to the gray level to pixels corresponding to two rows of scanning lines in order of a first precharge period, a first writing period, a second precharge period, and a second writing period, the writing periods having a longer duration than the precharge periods, and the precharge signal being applied simultaneously to the plurality of data lines, respectively;

wherein during the first and second precharge periods, the data-line driving circuit applies a data signal that makes the pixels black, and during the first and second writing periods, the data-line driving circuit applies a data signal corresponding to the gray level of the pixels corresponding to the scanning lines to which the selecting voltage is applied; and

a scanning-line driving circuit that applies a predetermined selecting voltage or nonselecting voltage to the plurality of rows of scanning lines, the scanning-line driving circuit including;

a shift register having output stages corresponding to the plurality of rows of scanning lines and outputting active-level signals from output stages corresponding to four rows that are separated from each other by a predetermined number of rows; and

a logic circuit provided to each output stage of the shift register, for carrying out a logic operation on

     1) the output signal from the output stage corresponding to the logic circuit itself and

     2) one of first to fourth enable signals, and applying the selecting voltage or nonselecting voltage to the scanning line that corresponds to the logic circuit on the basis of the logic operation, wherein

the logic circuits corresponding to adjacent eight rows of scanning lines input first, second, third, and fourth enable signals to corresponding two row sets; and

the first to fourth enable signals go to active level in some predetermined order of the first precharge period, the first writing period, the second precharge period, and the second writing period, during a period in which the signals from the output stages corresponding to the four rows go to active level, first to fourth enable signals going to active level;

row groups of the pixels that are made black during successive first precharge periods are next to row groups of the pixels to which a voltage corresponding to the gray level is written during successive first writing periods;

row groups of the pixels that are made black during successive second precharge periods are next to row groups of the pixels to which a voltage corresponding to the gray level is written during successive second writing periods;

row groups of the pixels that are made black during successive first precharge periods are remote from row groups of the pixels that are made black during successive second precharge periods; and

the first and second precharge data signals and the first and second writing data signals are each assigned to the first to fourth enable signals during a first clock period, and during a second clock period, the first and second precharge data signals and the first and second writing data signals assigned to the first to fourth enable signals are shifted.

5. The electrooptic device according to claim 4, wherein the precharge periods and writing periods all occur during one a half of a clock cycle.