DISPLAYS

Abstract

A display for mounting on a curved surface. The display includes a display stack comprising a substrate to conform to a curved surface; a pixelated display medium on the substrate; and a parallax barrier. The parallax barrier may comprise a pattern of light blocking elements to restrict viewing of pixels of the display medium to a viewing angle. In some implementations the parallax barrier may be configured so that positions of the light blocking elements, with respect to the pixels, change with lateral position on the display.

Claims

1. A display for mounting on a curved surface, the display having a display stack comprising: a substrate to conform to a curved surface; a pixelated display medium on the substrate; and a parallax barrier; wherein the parallax barrier comprises a pattern of light blocking elements to restrict viewing of pixels of the display medium to a viewing angle.

2. A display as claimed in claim 1, wherein the positions of the light blocking elements with respect to the pixels change with lateral position on the display.

3. A display as claimed in claim 1, wherein the positions of the light blocking elements with respect to the pixels change with lateral position on the display to compensate for a change in viewing angle with lateral position on the display when the display is mounted on the curved surface.

4. A display as claimed in claim 1, wherein the positions of the light blocking elements with respect to the pixels are increasingly offset from an initial relative position at an initial location with increasing lateral distance across the display from the initial location.

5. A display as claimed in claim 4, wherein the initial location is at a central lateral position on the display and/or wherein the initial relative position is a position where a light blocking element is centered on a pixel.

6. A display as claimed in claim 1, wherein the light blocking elements comprise stripes with a distance from one strip to an adjacent defined by a stripe pitch, wherein the pixels have a pixel pitch in the same direction as the stripe pitch, and wherein the stripe pitch is less than the pixel pitch.

7. A display as claimed in claim 1, wherein the curved surface curves in two dimensions, and wherein the positions of the light blocking elements with respect to the pixels change with lateral position on the display in two orthogonal directions.

8. A display as claimed in claim 7, wherein the light blocking elements define 2D frames around the pixels having windows defining the viewing angle in 2D.

9. A display as claimed in claim 1, wherein the parallax barrier is located between the pixelated display medium and a front surface of the display.

10. A display as claimed in claim 1, wherein the display has a light source behind the display, and wherein parallax barrier is located between the light source and the pixelated display medium.

11. A display as claimed in claim 1, wherein the pixelated display medium comprises a layer of LCD display medium including spacers to define a thickness of the layer of LCD display medium, and wherein the parallax barrier is integrated with the spacers.

12. A display as claimed in claim 1, wherein the light blocking elements comprise black resin.

13. A method of displaying information over a limited viewing angle using a curved display, the method comprising: providing a parallax barrier for the display comprising a pattern of light blocking elements to restrict viewing of pixels of the display to a viewing angle

14. A method as claimed in claim 13 further comprising: compensating for a change in viewing angle with respect to lateral position on the curved display by laterally positioning the light blocking elements.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Embodiments of the invention will be described, by way of example, with reference to the accompanying drawings, in which:

[0025] FIGS. 1a and 1b show example display stacks;

[0026] FIG. 2 shows a cross-sectional schematic view of a display incorporating a parallax barrier; and

[0027] FIGS. 3a to 3c show, respectively, first and second example parallax barriers for the display of FIG. 2, and an offset parallax barrier for an off-axis pixel.

DETAILED DESCRIPTION OF EMBODIMENTS

[0028] FIG. 1a illustrates a schematic cross-sectional view of an example display stack 100 of a liquid crystal display, which may be an OLCD (Organic LCD) display, where the TFTs are organic. In this example display stack the liquid crystal (LC) material 130 is disposed between a bottom (or first) encapsulation layer 115 and a top (or second) encapsulation layer 140. The LC material 130 is sandwiched by a LC cell top layer 135 and a LC cell bottom layer 120. An edge seal 125 is provided on both sides of the LC material 130. The LC layers are generally driven by control circuitry (not shown), for example, thin film transistors (TFTs) and associated electrical connections, disposed on the LC cell bottom 120. The control circuitry generally includes an array of thin film transistors (TFTs). In the case of OLCD (Organic LCD), where the TFTs are organic, the encapsulation layer 115 may be a thin film.

[0029] In the structure of FIG. 1a, a first polariser film or layer 110 is provided below the bottom encapsulation layer 115. A backlight layer 105 is provided below the first polariser film 110. The bottom encapsulation layer 115 could generally be a glass substrate. In the example of FIG. 1 which is an OLCD, the LC cell bottom 120 and LC cell top 140 are generally made of TAC (Cellulose Triacetate). The bottom encapsulation layer 115 may include an indium tin oxide (ITO) layer (not shown). The bottom encapsulation layer 115 and the first polariser film 110 generally form part of a driver component 76 of the display structure 100. The backlight layer 105 is generally a separate part from the display stack.

[0030] In the structure of FIG. 1a, a second polariser film 145 is provided on the top encapsulation layer 140. In one example, one side of the top encapsulation layer 140 there may be provided a colour filter layer (not shown); this may reside on the LC cell top layer 135. The encapsulation layer 140 may not be required if the LC cell Top is made of glass but in the case of an OLCD is generally present. The encapsulation film 140 could be integrated into the polariser 145 or LC cell top layer 135. The second polariser film 145, the top encapsulation layer 140 generally form part of a colour filter component 78 of the structure 100. The top encapsulation layer 140 is may be a glass substrate or may be a flexible organic-inorganic barrier, for example, in OLCDs.

[0031] FIG. 1b illustrates a schematic cross-sectional view of an example display stack 150 of an OLED (Organic Light Emitting Diode) display. The LCD display medium is replaced by OLED display medium 152 on substrate 154. The polariser is optional.

[0032] In each of FIGS. 1a and 1b the display and substrate(s) may be curved, for example fabricated from curved glass, or may be flexible, for example fabricated from plastic and employing organic TFTs. Details of suitable technology can be found on the Applicant's web site and in the Applicant's earlier published patent applications.

[0033] FIG. 2 shows a cross-sectional schematic view of a curved display 200 comprising a curved/flexible substrate 202 and having a plurality of display medium pixels 204 of which two 204a,b are shown. The display may comprise a display stack as previously described.

[0034] The display 200 of FIG. 2 includes a parallax barrier 210 comprising a plurality of light blocking elements 212 of which two 212a,b are shown. As shown in FIG. 3b, to limit viewing in one direction the parallax barrier may comprise stripes defining longitudinal windows over the pixels. As shown in FIG. 3a, to limit viewing in two directions the parallax barrier may comprise rectangular windows over each pixel.

[0035] A viewer 220 sees different parts of the display from different angles with respect to the surface of the display because of the curvature of the display. For example as illustrated the viewer sees a central part of the display straight-on, that is with a viewing direction 222a at 90 degrees to the central part of the display. However the same viewer sees the edge of the display at an acute angle, that is viewing direction 222b makes an acute angle to the surface of the display at the edge of the display. It will be appreciated that in general the viewing angles differ even when the central part of the display is viewed obliquely rather than straight-on.

[0036] The light blocking element 212a of the parallax barrier is arranged to obscure pixel 204a from viewing at angles beyond those defined by a viewing cone (or triangular prism for a 1D shield). This is approximately defined by the locations of the edges of light blocking element 212abeyond the viewing cone light blocking element 212a obscures the pixel 204a from view. The pixel has a finite lateral extent and thus the blocking is gradual rather than immediatefrom some intermediate angles a viewer may see part of the pixel, and thus a dimmed display.

[0037] In a similar way the light blocking element 212b of the parallax barrier is arranged to obscure pixel 204b from viewing at angles beyond those defined by the same viewing cone (or triangular prism). However because of the change in viewing direction to direction 222b the position of light blocking element 212b with respect to the underlying pixel 204b is preferably laterally shifted towards the centre of the display. This shift may be in one or two directions, depending upon whether the display is curved in one or two directions.

[0038] There may be one light blocking element per pixel. However the relative positions of these elements with respect to the underlying pixels may gradually shift across the display. They may have a slightly different pitch to the underlying pixels.

[0039] FIGS. 3a and 3b show example light blocking element shapes for 2D and 1D viewing angle limitation respectively. The underlying pixel is shown dashed. The position of the dashed regions with respect to the mask changes with lateral position on the display. FIG. 3c shows the pixel 204b offset with respect to the light blocking element 212b.

[0040] In the stack of FIG. 1a the parallax barrier may be located, for example, between layers 135 and 140 or 140 and 145; or between layers 120 and 130.

[0041] In general the parallax barrier may advantageously be formed in a planarising layer of the stack. For example for a viewing distance of order 1 metre the distance between the parallax barrier and pixel may be around 1-50 m, or 1-10 m. These distances are such that the parallax barrier may be formed is/using a planarising layer.

[0042] In some implementations liquid crystal layer 130 may include spacers. Potentially the parallax barrier and spacers may be integrated.

[0043] The light blocking elements may comprise metal but to reduce reflections black resin is preferable. A thickness in the range 0.1-1 m may be suitable for a metal barrier; a black resin barrier may have a thickness in the range 0.8-3 m, for example around 1 m)

[0044] Applications of the technology include, but are not limited to, in-vehicle displays, mobile phone/tablet displays, and ATM (Automated Teller Machine) displays.

[0045] No doubt many other effective alternatives will occur to the skilled person. It will be understood that the invention is not limited to the described embodiments and encompasses modifications apparent to those skilled in the art lying within the spirit and scope of the claims appended hereto.