GB2213305A

GB2213305A - Display device

Info

Publication number: GB2213305A
Application number: GB8827575A
Authority: GB
Inventors: Graham Leslie Wright; Richard Lynn Hedgley
Original assignee: Thorn EMI PLC
Current assignee: Thorn EMI PLC
Priority date: 1987-12-04
Filing date: 1988-11-25
Publication date: 1989-08-09
Also published as: GB8827575D0

Abstract

In a matrix display device, each pixel 2 comprises a first segment 4 of one colour which is at least in part encompassed by another segment 3 or a combination 3, 5 of segments of different colours to enable good colour blending as seen by an observer. The inner segment 4 may be of square shape. The segments may be of different sizes to take into account differing chromatic responses of the colours e.g. red, green, blue. The device may be of LC material and usable for colour as well as grey-scale displays. Corresponding segments of a plurality of pixels may be arranged collinear to one another for connection to a common drive line 6, 7 or 8. <IMAGE>

Description

DISPLAY DEVICE The present invention relates to a display device, and particularly but not exclusively to a liquid crystal display device.

British Patent Specification No. 1434121 discloses a liquid crystal display having a network of triangular horizontal electrodes and a network of triangular vertical electrodes in order to provide, by appropriate driving of overlapping vertical and horizontal electrodes, selective setting of triangular regions smaller in size than that of the triangular electrodes. The selectively settable triangular regions constitute the pixels of a dot matrix character display.

The present invention provides a display device comprising a matrix of pixels, a pixel comprising a plurality of pixel segments of different colour designation wherein a first pixel segment of one colour designation is at least in part encompassed by another pixel segment, or a combination of other pixel segments, of other colour designations.

In this way, good colour blending as perceived by an observer of the display can be achieved.

Preferably a plurality of pixels comprise pixel segments positioned collinear to one another and having the same colour designation whereby a common drive line can be provided for a plurality of pixel segments of the same colour designation.

Thus, by providing a pixel structure such that corresponding chromatic-designation segments along a plurality, i.e. a row, of pixels are aligned, a simple and convenient arrangement for row driving of a colour signal can be achieved.

Preferably, the segments of a pixel are not of the same size. In this way, the pixel structure can take due account of known differing chromatic response requiring a display input bias in favour of the green chrominance component.

In a preferred embodiment, a pixel comrises a plurality of generally triangular segments each of a different colour designation. Advantageously, one segment of a pixel is shaped to form substantially an isosceles triangle and two segments are shaped to form substantially right-angled triangles. Moreover, preferably the segments in a pixel are arranged with the apex of one segment adjacent the base of another. In this way, efficient use of the plate area and the area bounded by the pixel can readily be achieved.

In order that the invention may more readily be understood, a description is now given, by way of example only, reference being made to the accompanying drawings, in which: Figure 1 shows schematically part of a pixel structure embodying the present invention; Figures 2 and 3 show schematically other pixel structures.

Figure 1 shows the patterning arrangement of electrodes on the row plate for part of a row 1 of a liquid crystal display comprising a matrix of pixels. Each of the pixels, defined by the regions bounded by the broken lines (for example that as referenced by 2) comprises three pixel segments defined by three separate electrodes 3, 4 and 5 which are assigned (i.e.

designated), respectively, to the red, the green and the blue image information for that pixel. Red electrode 3 and blue electrode 5 are each in the shape of a right-angled triangle and are of the same area, while green electrode 4 is in the shape of an isosceles triangle and has an area which is twice that of the area of each of the other electrodes. These relative electrode areas ensure due allowance for image colour bias towards the green section of the colour spectrum. The horizontal, apex-to-base arrangement of the electrodes 3 to 5 as illustrated means that the green electrode 4 is at least in part encompassed by the combination of the red electrode 3 and blue electrode 5 and ensures efficient use of the plate surface and visually good colour-blending.The positioning of the pixels in the row so that the green electrodes of different pixels are collinear, the red electrodes of different pixels are collinear and the blue electrodes of different pixels are collinear allows convenient access to the associated electrodes in a row by the separate drive lines 6 to 8.

Figure 2 shows two end pixels in a row, the pixels having another patterning arrangement of electrodes for a liquid crystal display, each pixel being defined by the regions bounded by the broken lines, for example as referenced 10. Each pixel has a plurality of pixel segments formed by a central, square electrode 11 assigned to the red component of the image information for that pixel, two U-shaped electrodes 12 which together encompass electrode 11 and are assigned to the green component, and two U-shaped electrodes 13 which together encompass electrodes 12 and are assigned to the blue component. Three row drive lines 14 to 16 are provided, one each for all the red electrodes, the green electrodes and the blue electrodes respectively in the row. The electrodes 12 are connected together via the equivalent electrodes in the other pixels of the row; electrodes 13 are likewise connected.

Figure 3 shows another patterning arrangement in which each pixel 20 comprises a plurality of pixel segments formed by an electrode 21 assigned to the red component of the image information, an electrode 22 assigned to the green component, and an electrode 23 assigned to the blue component, with appropriate drive lines 24 to 26.

Any of the above patterning arrangements may be used in grey-scale displays as well as colour displays.

Clearly, a display may comprise a number of pixel rows, each comprising two electrode patterns of any of the above-described types arranged end-to-end symmetrically about their separation axis, such that the patterns are driven from opposite sides of the display.

Claims

1. A display device comprising a matrix of pixels, a pixel comprising a plurality of pixel segments of different colour designation wherein a first pixel segment of one colour designation is at least in part encompassed by another pixel segment, or a combination of other pixel segments, of other colour designations.

2. A display device according to Claim 1 wherein a plurality of pixels comprise pixel segments positioned collinear to one another and having the same colour designation whereby a common drive line can be provided for a plurality of pixel segments of the same colour designation.

3. A display device according to Claims 1 or 2, a pixel comprising one or more pixel segments of each of the colours red, green and blue wherein the area presented by the one or more pixel segments of the colour green is greater than the area presented by the one or more pixel segments of each of the colours red or blue.

4. A display device according to any one of the preceding claims wherein a pixel comprises a plurality of generally triangular segments each of a different colour designation.

5. A display device according to Claim 4 wherein said first pixel segment is shaped to form substantially an isosceles triangle and another two segments are each shaped to form substantially right-angled triangles.

6. A display device according to any one of Claims 1 to 3 wherein said first pixel segment is encompassed by one or more pixel segments of another colour designation.

7. A display device according to any one of Claims 1 to 3 wherein said first pixel segment is encompassed by more than one pixel segment, said more than one pixel segment having colour designations of more than one colour.

8. A display device according to Claims 6 or 7 wherein said first pixel segment is square.

9. A display device substantially as hereinbefore described with reference to, and as illustrated in, any one of the accompanying drawings.