Method and apparatus for controlling a multigradation display

• US 5,252,959 A
• Filed: 07/27/1992
• Issued: 10/12/1993
• Est. Priority Date: 02/20/1989
• Status: Expired due to Term

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Kono, Masaru
• Primary Examiner(s): Weldon, Ulysses
• Assistant Examiner(s): Liang, Regina
• Application Number:
  US07/921,443
• Time in Patent Office: 442 Days
• Field of Search: 340/793, 340/784, 340/767, 340/701, 340/805, 358/455-459
• US Class Current: 345/694
• CPC Class Codes: G02F 1/134345 Subdivided pixels, e.g. for grey scale or redundancy
• CPC Class Codes: G09G 3/2025 the sub-frames having all the same time duration
• CPC Class Codes: G09G 3/2051 with use of a spatial dither pattern
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers

Abstract

A multi-gradation display control method comprises activating selected dots in selected of a plurality of defined submatrices together constituting the entire dot matrix display, e.g., a two dimensional LCD panel, whereby a distribution of dispersion field of dots within defined submatrices are activated to display an image in multi-gradations. A defined dot submatrix has a predetermined distribution of individual activated or unactivated dots in a single frame to form a predefined gradation pattern. The predetermined distribution of dots is changed in succeeding frames of the entire dot matrix so that the dot positions activated or unactivated in a succeeding frame are not the same dot positions activated or unactivated in a previous frame. Preferably, the dot position activated in any given frame of a defined n dots by n dots submatrix are not adjacent to dot positions activated in a previous frame and are not adjacent to dot positions to be activated in a succeeding frame. At least two different two dimensional sizes of submatrices are provided to form a series of multi-gradations. As a result, defined dot matrices of different sizes are determined for different gradations wherein different gray scale representations can be produced without substantial pattern interference or objectionable fringes annoying to the naked eye.

Claims

1. A multi-gradation display comprising:

display means comprising a field of dots formed in a matrix for displaying an image,

a plurality of parallel signal electrodes and a plurality of scan electrodes formed in orthogonal directions relative to each other, the cross points of said electrodes defining said field of dots,

scan electrode driving means having a plurality of scan signal output terminals for sequentially supplying scan signals to respective scan electrodes,

signal electrode driving means for selectively supplying data signals to respective signal electrodes,

electrode driving means for activating selected dots to form said image across said matrix field of dots,

said matrix field of dots divided into a plurality of defined virtual submatrices of different two dimensional size and forming a predetermined gradation pattern of N activated or nonactivated dots distributed within each of said defined virtual submatrices, each of said virtual submatrices having at least a different number of rows of dots in one of said orthogonal directions compared with other of said virtual submatrices,

said electrode driving means comprising;

gradation data encoder means for designating a particular gradation for the display of the image,

dot submatrix generating means comprising a plurality of submatrix generating circuits for respectively generating one of said virtual submatrices with said predetermined gradation pattern of N activated or nonactivated dots,

output gate means for applying data signals for creating an activated dot gradation per respective submatrix addressed by said electrode driving means based upon on outputs of said gradation data encoder means and said dot submatrix generating means.

2. A multi-gradation display according to claim 1 wherein said scan electrode driving means provides scan signal outputs in excess of the number of said scan electrodes.

3. A multi-gradation display according to claim 1 wherein the number of said scan signal output terminals exceeds the number of scan electrodes by an amount equal to the largest number of dot rows in said one orthogonal direction for any generatable dot submatrix plus 1.

4. A multi-gradation scheme in a display apparatus for application to a plurality of two dimensional submatrices together forming a dot matrix display of an image to be displayed which is refreshed per frame addressing of the entire field of dots in the matrix display and comprising a series of gradation patterns for application to said submatrices wherein at least one of said submatrices is defined to have a different dimensional size along at least one m or n side thereof as compared to at least several others of said submatrices in the display wherein different sizes of said gradation patterns represent different gradation levels, said gradation patterns comprising a predetermined dot distribution of N activated or nonactivated dots within each of said submatrices, said predetermined dot distribution being laterally shift within each respective submatrix at least one dot position in each consecutive frame of display of said image.

5. The multi-gradation scheme of claim 4 wherein said predetermined dot distribution is shifted a predetermined number of frames until the reappearance of said predetermined dot distribution in a first frame displayed whereby each dot in each of said submatrices is displayed at least once in said predetermined number of frames and are displayed an equal number of times over said predetermined number of frames.

6. The multi-gradation scheme of claim 5 wherein the two dimensional size of said at least one of said submatrices contains less m rows wherein a largest defined of said submatrices in said gradation pattern series is defined as n rows by m rows of dots.

7. The multi-gradation scheme of claim 4 wherein the two dimensional size of said at least one of said submatrices contains less m rows wherein a largest defined of said submatrices in said gradation pattern series is defined as n rows by m rows of dots.

8. The multi-gradation scheme of claim 7 wherein there are more than two different dimensional sizes of said submatrices.

9. The multi-gradation scheme of claim 8 wherein said largest defined submatrix is 8 rows by 8 rows of dots, at one other of said submatrices is 8 rows by 5 rows of dots and at least one other of said matrices is 8 rows by 3 rows of dots.

10. The multi-gradation scheme of claim 7 wherein the dots in said predetermined dot distribution are laterally shifted within each of said submatrices in a manner that the individual dots within each of said submatrices are not positioned adjacent to one another in consecutive frames.

11. The multi-gradation scheme of claim 7 wherein the dots in said predetermined dot distribution are laterally shifted within each of said submatrices so that the individual dots within each of said submatrices are not positioned adjacent to one another in consecutive frames.

12. A method of controlling a multi-gradation display comprising a display matrix of dots in rows formed in orthogonal directions of the matrix and wherein dots are selectively activated or not activated to form a displayed image said method comprising the steps of

(a) dividing said display matrix into a plurality of virtual, two dimensional submatrices each comprising a plurality of display dots together which form the displayed image,

(b) providing different orthogonal boundary sizes to said submatrices wherein each of the submatrices has a two dimensional size, of m dot rows in a first direction, X, by n dot rows in a second direction, Y, orthogonal to said first direction, X, and the size of at least some of said submatrices differing from the size of at least some of the others of said submatrices by at least a difference in the total number of dot rows in one of said orthogonal directions X or Y,

(c) defining each of said submatrices of a given size, m by n, as a gradation level, wherein each such level comprises a pattern of N activated or nonactivated dots distributed throughout a given submatrix and accordingly activated or nonactivated within a single display frame of the image to be displayed,

(d) dynamically selecting different gradation levels, g, to complete said formed display image according to the white, black and gray scale representations of portions of the image to be displayed,

(e) sequentially shifting the pattern of distributed positions of N activated or nonactivated dots within each of the selected gradation levels, g, to new laterally disposed positions of N activated or unactivated dots within each of the selected gradation levels, g, over successive display frames of the displayed image until K display frames have transpired wherein K is equal to said dot rows total number in said one orthogonal direction relative to each of the selected gradation levels, g, and

(f) repeating the N dot distributed position shifting of step (e) over successive groups of K display frames until the displayed image is changed to a different displayed image wherein steps (d), (e) and (f) are repeated until the displayed image is again changed.

13. The method according to claim 12 wherein the distributed N dots in each of the selected gradation levels, g, is equal to said dot rows total number in said one orthogonal direction.

14. The method according to claim 13 wherein the occurrence in K display frames of adjacently disposed activated or nonactivated N dots appearing in immediately adjacent row positions of rows of dots in the other of said respective orthogonal directions of each of the selected gradation levels is designed to be of a minimum occurrence.

15. The method according to claim 12 wherein the lateral shifting of the distributed N dots in successive display frames of the displayed image is at least one dot row position.

16. The method according to claim 12 wherein the lateral shifting of the distributed N dots is uniformly in one direction across each of the selected gradation levels.

17. The method according to claim 16 wherein the lateral shifting of the distributed N dots is uniformly in one orthogonal or diagonal direction across each of the selected gradation levels.

18. The method according to claim 16 wherein the lateral shifting of the distributed N dots is at least one dot row position.

19. The method according to claim 18 wherein the lateral shifting of the distributed N dots of dot row positions is greater than one row of dots.

20. The method according to claim 18 wherein the lateral shifting of the distributed N dots of dot row positions is an integer less than eight.

21. The method according to claim 12 wherein the size of at least some of the submatrices differ from the size of at least some of the other submatrices by a difference in the total number of rows of dots m and n in both of said orthogonal directions X and Y.

22. The method according to claim 12 wherein there are three different two dimensional sizes of submatrices.

23. The method according to claim 22 wherein the sizes of the submatrices comprise three pairs of submatrices comprising six gradation levels wherein submatrices of each pair respectively have N activated or N nonactivated dots and wherein said submatrix pairs respectively comprise 3 dot rows, 5 dot rows and 8 dot rows in said one orthogonal direction.

24. The method according to claim 12 wherein

the distributed N dots in a given submatrix is equal to the number of dot rows in the other of said orthogonal directions wherein said number of dot rows is the same in the selected gradation levels, g,

the distributed N dots are randomly positioned along m and n rows so that to the extent possible a distributed N dot in any such row is not immediately adjacent to a distributed N dot in an immediately adjacent row m or n,

the lateral shifting of the distributed N dots in successive display frames is accomplished without change in the pattern of the original N dot spatial distribution through the submatrices, and

the lateral shifting of the distributed N dots is accomplished uniformly in one direction across the array whereby gradation pattern interference is significantly reduced.

25. The method according to claim 12 wherein

the distributed N dots in a given submatrix is equal to the number of dot rows in the other of said orthogonal directions wherein said number of dot rows is the same in the selected gradation levels, g,

each distributed N dot in a submatrix is positioned along a respective row of the submatrix in a manner that a distributed N dot in any such row is not immediately adjacent to a distributed N dot in an immediately adjacent row of the same submatrix,

the lateral shifting of the distributed N dots in successive display frames is accomplished without change in the pattern of the original N dot spatial distribution through the submatrices, and

the lateral shifting of the distributed N dots is accomplished uniformly in one direction across the array whereby gradation pattern interference is significantly reduced.

26. A method of controlling a display to provide multiple levels of gradation during displayed frames of an image on a dot matrix display comprising the steps of:

dividing the dot matrix display into a plurality of two or more virtual dot submatrices each comprising a plurality of dot rows and columns,

designating a number of gradation levels, g, of the image to be displayed relative to a group of said virtual dot submatrices individually differing from one another in at least one dimensional direction by the number of rows m or n,

selecting different virtual dot submatrices from said group depending on the gradation level of the image to be displayed,

activating a predetermined pattern of dots in each selected virtual dot submatrix according to designated gradation levels of the image to be displayed,

laterally shifting the activated predetermined pattern of dots at least one dot position through the selected virtual dot submatrices in each display frame period, and

continuing the lateral shifting and repeating the patterns of lateral shifting of the activated predetermined pattern of dots through the selected virtual dot submatrices in successive display frame periods until the image to be displayed is changed.

27. A method of controlling multi-gradation relative to the display of dots in a matrix of columns and rows of dots forming a two-dimensional display of an image to be displayed per unit frame comprising the steps of:

dividing the display dot matrix into a plurality of two dimensional dot submatrices differing from each other in their size in at least one orthogonal direction by the number of rows or columns determining their boundary size resulting in a different number of display dots per submatrix to respectively provide a different level of gradation,

selecting different dot submatrices according to the gradation level of portions the image to be displayed,

dynamically changing the arrangement of the different two dimensional dot submatrices across the dot matrix according to changes desired in the gradation level due to changes in the image to be displayed,

determining a distribution and number of dots to be actuated throughout each selected dot submatrix per unit frame, and

selectively actuating the determined distribution of dots in each dot submatrix to be displayed per unit frame, and

laterally shifting the determined distribution of actuated dots within each dot submatrix in successive display frames of the image.

28. The method according to claim 27 wherein the boundary size of dot submatrices is different in the number of dot rows in one orthogonal direction of the submatrices.

29. The method according to claim 28 wherein the boundary sizes of dot submatrices comprise dot rows three rows, five rows and eight rows.

30. The method according to claim 27 wherein the actuated dots in each column or row of a displayed dot submatrix are uniformly shifted across the dot submatrices in successive display frames by more than one column or row.

31. The method according to claim 27 wherein actuated dots in a selected dot submatrix are dispersed throughout the matrix and shifted within the dot submatrix in successive frames in a manner that actuated dots within said selected dot submatrix in a next successive frame in a given column or row are positioned so as not to be adjacent to actuated dots in an immediately adjacent column or row of said selected dot matrix in an immediately previous or subsequent display frame.

32. The method according to claim 27 wherein the position of actuated dots in a displayed dot submatrix are laterally shifted by a predetermined number of dot rows or columns in a predetermined direction across a displayed dot submatrix in successive display frames.

33. The method according to claim 27 wherein said actuated determined distribution of dots in said selected dot submatrices comprises a select group of dots having a first binary value distributed within a majority of submatrix dots having a second binary value, either the first or second binary value being an activated state and the other being a nonactivated state.

34. A multi-gradation display comprising:

display means for displaying an image in a display frame period comprising a plurality of dots at the cross points of a plurality of spatially parallel signal electrodes 3₁ -3₃₄₀ and a plurality of spatially parallel scan electrodes 2₁ -2₂₀₀,

scan electrode drive means 4 for supplying scan signals in sequential order to said scan electrodes,

signal electrode drive means 5 for supplying data signals to said signal electrodes,

said scan electrode drive means and signal electrode drive means together creative of dots at said scan electrodes and signal electrodes cross points where said scan and data signals are activated to form the displayed image,

said signal electrode drive means 5 comprising

gradation data decoder means 6 to provide for selection of gradation levels according to the gradation requirements of the displayed image,

dot submatrix generating means 7 for respectively creating a series of two dimensional dot submatrices at least some of which differ in at least one dimensional direction each establishing a predetermined gradation level to be displayed, and

output gate means GT₁ -GT₈ for applying data signals for creating an activated dot gradation per respective submatrix addressed by said signal electrode driving means based upon on outputs of said gradation data encoder means and said dot submatrix generating means.

35. The display according to claim 34 wherein said scan electrode drive means 4 is provided with a greater number of scan signal output terminals X₁ -X₂₀₉ than the number of scan electrodes 2₁ -2₂₀₀.

36. The display according to claim 35 wherein the total number of scan signal output terminals X₁ -X₂₀₉ utilized in the display of the image is determined by the combined total number of dot rows of displayed submatrices in the direction of scanning of said electrodes 2₁ -2₂₀₀.