Liquid crystal display device

• US 5,621,425 A
• Filed: 12/21/1993
• Issued: 04/15/1997
• Est. Priority Date: 12/24/1992
• Status: Expired due to Term

• Current Assignee: Seiko Instruments Incorporated (Seiko Group)
• Original Assignee: Seiko Instruments Incorporated (Seiko Group)
• Inventors: Hoshino, Masafumi, Senbonmatsu, Shigeru, Oniwa, Hirotomo, Yamamoto, Shuhei
• Primary Examiner(s): Hjerpe, Richard
• Assistant Examiner(s): WU, XIAO MIN
• Application Number:
  US08/172,633
• Time in Patent Office: 1,211 Days
• Field of Search: 345/87, 345/88, 345/89, 345/94, 345/95, 345/96, 345/97, 345/98, 345/99, 345/100, 345/103, 359/54, 359/55, 382/41, 382/43, 382/281, 382/276
• US Class Current: 345/94
• CPC Class Codes: G09G 3/2011 by amplitude modulation
• CPC Class Codes: G09G 3/3625 using active addressing

Abstract

The liquid crystal display device is comprised of a matrix panel 1, a common driver 2 and a segment driver 3. A liquid crystal layer is interposed between rows of the scanning electrodes 4 and columns of signal electrodes 5. A frame memory 6 stores an inputted dot data each frame. An orthonormal signal generator 7 generates a set of orthonormal signals to sequentially feed the same in a desired combination pattern to the common driver 2 to concurrently drive a multiple of the scanning electrodes 4 to effect group sequential scanning according to the combination pattern. A dot product computation unit 8 executes dot product computation between a set of the dot data and the set of the orthonormal signals, the result of which is fed to the segment driver 3 to drive the columns of the signal electrodes 5. The group sequential scanning is repeated several times within one cycle to display a picture. The orthonormal signals are horizontally or vertically shifted to improve the quality of the displayed picture. Further, the multiple concurrent line number is optimized to balance the withstand voltage between the common driver 2 and the segment driver 3. Moreover, in the gray shading display by pulse-height modulation, a voltage pulse assigned to a virtual line of the scanning electrode is spread out to improve the gray shaded quality of the displayed picture.

Claims

1. A liquid crystal display device comprising:

a matrix panel comprising a plurality of rows of scanning electrodes, a plurality of columns of signal electrodes, and a liquid crystal layer interposed therebetween;

a common driver for driving the rows of the scanning electrodes;

a segment driver for driving the columns of the signal electrodes;

orthonormal signal generating means for producing a set of orthonormal signals in orthonormal relation with one another and sequentially providing the orthonormal signals in a predetermined combination pattern to the common driver so as to selectively simultaneously drive a predetermined number of the scanning electrodes to effect group sequential scanning according to the combination pattern;

a frame memory for storing input dot data corresponding to an image to be displayed during each frame;

dot product computation means for computing a dot product of a set of input dot data sequentially retrieved from the frame memory and the set of orthonormal signals transferred from the orthonormal signal generating means, and for applying a computed dot product to the segment driver to drive the columns of the signal electrodes; and

synchronizing means for synchronizing a retrieval timing of the dot data from the frame memory with a transfer timing of the orthonormal signals from the orthonormal signal generating means to thereby repeat the group sequential scanning plural times within each cycle;

wherein the orthonormal signal generating means includes means for horizontally shifting a phase of the set of orthonormal signals in response to the group sequential scanning to form the combination pattern and for performing one of vertically shifting and interchanging the orthonormal signals each cycle of the group sequential scannings to for the combination pattern.

2. A liquid crystal display device comprising:

a matrix panel comprising a plurality of rows of scanning electrodes, a plurality of columns of signal electrodes, and a liquid crystal layer interposed therebetween;

a common driver for driving the rows of scanning electrodes;

a segment driver for driving the columns of signal electrodes according to input dot data corresponding to an image to be displayed;

means for sequentially providing a set orthonormal signals to the common driver for selectively driving a group comprising multiple rows of scanning electrodes to effect group sequential scanning; and

means for computing a dot product of a set of the input dot data and the set of orthonormal signals to produce dot product signals and to provide the dot product signals to the segment driver to drive the columns of signal electrodes in synchronization with the group sequential scanning;

wherein the number of rows of multiple scanning electrodes contained in one group is optimized to balance a withstand voltage between the segment driver and the common driver.

3. A liquid crystal display device according to claim 2;

wherein the number of rows of multiple scanning electrodes contained in a group is set to approximately the square root of the total number of rows of scanning electrodes.

4. A method of driving a liquid crystal display having a plurality of rows of scanning electrodes, a plurality of columns of signal electrodes and a liquid crystal layer interposed therebetween, comprising the steps of:

organizing the display into a plurality of groups, each group comprising multiple rows of scanning electrodes;

concurrently selecting a group of multiple rows of scanning electrodes to apply thereto respective scan signals;

applying data signals to the signal electrodes in synchronization with the scan signals; and

sequentially scanning each group of multiple rows of scanning electrodes to perform a frame scanning, wherein the scan signals have different voltage levels when applied to respective ones of the concurrently selected rows of electrodes in the group such that the scan signals take on a predetermined combination pattern for each group of multiple rows of scanning electrodes and the combination pattern is repeated cyclically each time a predetermine number of frame scannings is carried out, and the combination pattern corresponding to a selected group and the combination pattern corresponding to the succeeding selected group are different from each other within the same frame scanning.

5. A method of driving a liquid crystal display having a plurality of rows of scanning electrodes, a plurality of columns of signal electrodes and a liquid crystal layer interposed therebetween, comprising the steps of:

organizing the display into a plurality of groups, each group comprising multiple rows of scanning electrodes;

concurrently selecting a group of multiple rows of scanning electrodes to apply thereto respective scan signals;

applying data signals to the signal electrodes in synchronization with the scan signals; and

sequentially scanning each group of multiple rows of scanning electrodes to perform a frame scanning, wherein the scan signals have different voltage levels when applied to respective ones of the concurrently selected rows of scanning electrodes in the group such that the scan signals take on a predetermined combination pattern for each group of multiple rows of scanning electrodes and the combination pattern is repeated cyclically each time a predetermined number of frame scannings is carried out, and the combination pattern corresponding to each group of multiple rows of scanning electrodes during a frame scanning is different from the combination pattern corresponding to the same group during a succeeding frame scanning.

6. A method of driving a liquid crystal panel having a plurality of rows of scanning electrodes, a plurality of columns of signal electrodes and a liquid crystal layer interposed therebetween, comprising the steps of:

organizing the display into a plurality of groups, each group comprising multiple scanning electrodes;

concurrently selecting a group of a multiple rows of scanning electrodes to apply thereto respective scan signals;

applying data signals to the columns of signal electrodes in synchronization with the scan signals; and

sequentially scanning each group of multiple rows of scanning electrodes to perform a frame scanning, wherein the scan signals have different voltage levels when applied to respective ones of the concurrently selected rows of scanning electrodes such that the scan signals constitute a predetermined combination pattern for each group of multiple rows of scanning electrodes and the combination pattern is repeated cyclically each time a given number of the frame scannings are carried out, and wherein each signal electrode has a data signal voltage G_j (t) applied thereto computed according to the following equation based on the scanning signal F_i (t) and a dot data I_ij ;

##EQU11## where i=1,2,3 . . . is a respective of row of scanning electrodes, j=1,2,3, . . . is a respective column of signal electrodes, N is the total number of rows of scanning electrodes and V.sub.(L+1).sbsb.j denotes data assigned to a virtual line of the scanning electrode and added once for each group of L scanning electrodes, wherein L is the number of rows of scanning electrodes in each group, and is computed according to the following equation;

##EQU12## whereby the data of the virtual line is added equidividedly each time L rows of scanning electrodes are selected.

7. A method of driving a liquid crystal display having (N) rows of scanning electrodes, a plurality of columns of signal electrodes and a liquid crystal interposed therebetween, comprising the steps of:

organizing the display into a plurality of groups, each group comprising (L) rows of scanning electrodes;

concurrently selecting a group of (L) scanning rows of electrodes to apply thereto respective scan signals;

applying data signals to the columns of signal electrodes in synchronization with the scan signals; and

sequentially scanning each group of multiple rows of (L) scanning electrodes to perform a frame scanning, wherein the scan signals have different voltage levels when applied to respective ones of the concurrently selected rows of scanning electrodes such that the scan signals constitute a given combination pattern for each group of multiple rows of scanning electrodes and the combination pattern is repeated cyclically each time a predetermined number of frame scannings is carried out, and wherein each signal electrode column has a data signal voltage G_j (t) applied thereto which is computed according to the following equation based on the scanning signal F_i (t) and input dot data I_ij ;

##EQU13## wherein i=1,2,3, . . . is the number of rows of scanning rows, j =1,2,3, . . . is the number of columns of signal electrodes, N is the total number of rows of scanning electrodes and V_kj denotes data assigned to a virtual line of the scanning electrode and added once for each group of L scanning electrodes, and is computed according to the following equation;

##EQU14## whereby the data of the virtual line which is added at the (L+1)th line is calculated for addition each time L rows of scanning electrodes are selected according to the dot data assigned to the L scanning electrodes.

8. A method of driving a liquid crystal display having a plurality of rows of scanning electrodes, a plurality of columns of signal electrodes and a liquid crystal layer interposed therebetween, comprising the steps of:

organizing the display into a plurality of groups, each group comprising multiple rows of scanning electrodes;

concurrently selecting a group of multiple rows of electrodes to apply thereto respective scan signals;

applying data signals to the columns of signal electrodes in synchronization with the scan signals; and

sequentially scanning each group of multiple rows of scanning electrodes to perform a frame scanning, wherein the scan signals have different voltage levels when applied to respective ones of the concurrently selected rows of scanning electrodes such that the scan signals constitute a given combination pattern for each group of multiple rows of scanning electrodes and the combination pattern is repeated cyclically each time a predetermined number of frame scannings is carried out, and wherein each signal electrode has a data signal voltage G_j (t) applied thereto which is computed according to the following equation based on the scanning signal F_i (t) and input dot data I_ij ;

##EQU15## where i=1, 2,3, . . . is the number of rows of scanning electrodes, j=1,2,3, . . . is the number of columns of signal electrodes N is the total number of rows of scanning electrodes L is the number of scanning electrodes in each group and V_kj denotes a data assigned to a virtual line of the scanning electrode and added once for each group of L scanning electrodes, and is computed according to the following equation;

##EQU16## whereby the data of the virtual line which is added at the (L+1)th line is calculated for addition each time L rows of scanning electrodes are selected according to previous dot data assigned to the L rows of scanning electrodes when selected for scanning "A" times earlier where "A" denotes an integer less than ten.