CN101105579A

CN101105579A - Multiple view directional display

Info

Publication number: CN101105579A
Application number: CNA200710127494XA
Authority: CN
Inventors: J·马色; D·U·基恩; R·文罗; G·布西尔; 中川朗
Original assignee: Sharp Corp
Current assignee: Sharp Corp
Priority date: 2003-08-30
Filing date: 2004-08-30
Publication date: 2008-01-16
Anticipated expiration: 2024-08-30
Also published as: CN100576018C; JP4471785B2; KR20050022955A; KR100679189B1; JP4999173B2; GB2405542A; JP2008020933A; CN1617014A; GB0320358D0; CN100406964C; KR100772758B1; JP2005078094A; KR20060134897A

Abstract

A display for displaying three dimensional (3D) stereoscopic or multiple directional images comprises a dual view display 19 which may be an LCD and a directional backlight or illumination arrangement 20. Back lighting system 20 comprises a partially collimated backlight source 21 and a prism structure 22 directing outputted light into different directions such that an image may be viewed in, for example, two positions at various angles. As shown in more detail in Figure 6b, the illumination source 21 may comprise a rear reflector (26), light source and waveguide arrangement (23a, 25), and collimating prism structures (27, 28). The multiple direction display may be arranged to direct no light into a region between imaging viewing directions, i.e. provide a ''black window'' normal to the plane of the display between dual image regions. A parallax barrier may further prevent the projected images being observed in certain regions, and pixel colour filters may be provided.

Description

Multi-view directional display

This application is a divisional application of the application filed on 8/30/2004 under the application number 200410089918.4 entitled "multi-view directional display".

Technical Field

The invention relates to a multi-view directional display displaying two or more images so that the respective images are visible from different directions. Thus, two viewers viewing the display from different directions will see images that are different from each other. The above-described display may be used, for example, in a free-standing display device or a dual-view display device. The invention also relates to a parallax barrier substrate, and a method of manufacturing a multi-view directional display.

Background

Conventional display devices have been designed to be viewed simultaneously by multiple users. The display characteristics of the display device allow a viewer to see equally good image quality from different angles of the display. This is useful when many users need to get the same information from the display, such as the display of departure information at airports and train stations. However, in many applications, it is desirable that each user can see different information from the same display. For example, in an automobile a driver may wish to see satellite navigation data, but a passenger may wish to watch a movie. This conflict needs to be met by providing two separate display devices, but this will take extra space and will increase the cost. Further, if two separate displays are used in the above example, if the driver moves his or her head, the driver may view the passenger's display, distracting the driver. As a further example, each of two or more players in a computer game may wish to view the game from his or her own perspective. Currently each player views the game on a separate display screen, such that each player views their own unique perspective on their respective display screen. However, providing a separate display screen for each player takes a lot of space and is expensive and impractical in portable games. To solve the above problems, multi-view directional displays have been developed. One application of a multi-view directional display is as a "dual-view display" that can simultaneously display two or more different images, each image visible only in a particular direction, so that a viewer looking at the display device from one direction will see one image, but a viewer looking at the display device from a different direction will see a different image. A display that can display different images to two or more users offers a possibility to take into account space and cost savings compared to using two or more separate displays.

Examples of possible applications of the multi-view directional display device have been given above, but many other applications exist. For example, it may be used on board an aircraft to provide each passenger with a separate in-flight entertainment program. Currently, a separate display device is provided to each passenger, typically at the back of the front row of seats. Using a multi-view directional display may save cost, space and weight as it enables one display to be used for two or more passengers and still allow each passenger to select their own movie selection.

A further advantage of the multi-view directional display is the ability to exclude a user from viewing others' views. This is desirable in applications requiring security, such as banking or sales transactions, for example using Automated Teller Machines (ATMs) and the example of computer games described above.

A further application of multi-view directional displays is the generation of three-dimensional displays. In normal display, the human eyes perceive views of the world from different perspectives (perspective) due to their different positions on the human head. These two perspectives (perspective) are used by the brain to estimate the distance to different objects in the scene. In order to create a display that efficiently displays three-dimensional images, the location must be reconstructed to provide a so-called "stereo pair" of images, i.e. images corresponding to each eye of the viewer.

Three-dimensional displays are classified into two types according to a method of providing different views to eyes of different viewers. Stereoscopic displays typically display two images of a stereoscopic image pair over a wide viewing area. Each view is encoded, for example by color, polarization state, or display time. The user is required to wear glasses as a filtering system with separate views so that each eye sees only the corresponding view.

The self-stereoscopic display displays the right eye view and the left eye view in different directions, so that each view is only visible in a respective customized spatial region. The spatial region where the image is visible in the entire display activation region is defined as a "viewing window". If the viewer is positioned such that the left eye is in the viewing window of the left eye view of the stereoscopic pair and the right eye is in the viewing window of the left eye view of the stereoscopic pair, the correct view will be seen by each eye of the viewer and the three-dimensional image will be perceived. Self-stereoscopic displays require no viewing assistance by the viewer.

The self-stereoscopic display is in principle the same as the dual view display. However, the two images displayed on the self-stereoscopic display are left-eye and right-eye images of a stereoscopic image pair and are therefore not independent of each other. Further, two images are displayed so as to be visible to a single viewer, one image being visible to one eye of the viewer.

For flat-platform, self-stereoscopic displays, the viewing window is typically formed by a combination of the image cell (or "pixel") structure and the optical cell of the image display unit of the self-stereoscopic display, commonly referred to as a parallax mirror. An example of a parallax optic is a parallax barrier, which is a screen having transmissive areas, usually in the form of slits, separated by opaque areas. Such a screen can be arranged in front of or behind a Spatial Light Modulator (SLM) with a two-dimensional array of picture elements, resulting in a free-standing display.

Fig. 1 is a plan view of a known multi-view orientation apparatus, if this is a free-standing display. The directional display 1 comprises a Spatial Light Modulator (SLM) 4, and a parallax barrier 5, which constitute the image display device. The SLM in fig. 1 is a Liquid Crystal Display (LCD) comprising an active matrix Thin Film Transistor (TFT) substrate 6, an opposite substrate 7, and a liquid crystal layer 8 between the substrate and the opposite substrate. The SLM has addressing electrodes (not shown) defining a plurality of individually addressed picture elements and also has alignment layers (not shown) for aligning the liquid crystal layer. The viewing angle enhancement film 9 and linear polarizer 10 are located on the outer surface of

base

6,7. The illumination 11 comes from backlight (not shown).

The parallax barrier 5 comprises a substrate 12 with a parallax barrier slit array 13 formed in its surface adjacent the SLM 4. The slot array comprises vertically extending (that is, extending into the plane of the paper in figure 1) transparent slots 15 separated by opaque members 14. An Antireflection (AR) coating 16 is formed on the opposite side of the parallax barrier substrate 12 to that formed on the output surface of the display 1.

The pixels of the SLM4 are arranged in rows and columns, and the columns extend into the plane of the paper in fig. 1. The pixel pitch (the distance from the center of one pixel to the center of an adjacent pixel) in the row or horizontal direction is p. The width of the vertically expanding transmission slit 15 of the slit array 13 is 2w, and the horizontal pitch of the transmission slit 15 is b. The spatial distance between the plane of the spacer slot array 13 and the plane of the liquid crystal layer 8 is s.

In use, the display device 1 forms left and right eye images and a three dimensional image will be seen by a viewer with their head positioned such that their left and right eyes coincide with the left and right eye viewing windows 2,3 respectively. Left and right eye viewing windows 2,3 are formed in window plane 17 at a desired viewing distance from the display. The distance between the plane of the window and the plane of the slot array 13 is r _o . The windows 2,3 abut in the window plane with a spacing e corresponding to the average spacing between the eyes of the person. The half angle from the vertical axis to the center of each window 2,3 and the display normal is α.

The pitch of the slits 15 of the parallax barrier 5 is chosen to be close to an integer multiple of the pixel pitch of the SLM4 so that groups of pixel columns are associated with a particular slit of the parallax barrier. Fig. 1 depicts a display device in which two pixel columns of the SLM4 are associated with each transmissive slit 15 of the parallax barrier.

Fig. 2 depicts the angular area of light generated from the SLM4 and the parallax barrier 5 where the pitch of the parallax barrier is exactly an integer multiple of the pixel column pitch. In this case, corner regions from different locations blend across the display panel surface, and pure regions of view image 1 or image 2 (where "image 1" and "image 2" represent the two images displayed by the SLM 4) do not exist. For addressing this, the pitch of the parallax barrier is preferably slightly reduced so as to be slightly smaller than an integral multiple of the pixel column pitch. The angular regions thus converge in a predefined plane in front of the display ("window plane"). This effect is illustrated in the associated figure 3, which depicts the image area produced by the SLM4 and the modified parallax barrier 5'. When produced in this manner, the viewing area is substantially kite-shaped in plan view.

Fig. 4 depicts a plan view of another known multi-view directional display device 1'. Corresponds in general to the display device 1 of the accompanying fig. 1, except that the parallax barrier 5 is located behind the SLM4 and thus between the backlight and the SLM 4. Such a device may have the advantage that the parallax barrier is less visible to a viewer, and the pixels of the display appear closer to the front of the device. Further, although fig. 1 and 4 depict transmissive display devices illuminated by backlight, reflective devices using ambient light (in bright environments) are known. In a transmissive device, the rear parallax barrier in fig. 4 will not absorb ambient light. This is an advantage if the display has a 2D mode using reflected light.

In the display device of fig. 1 and 4, a parallax barrier is used as the parallax mirror. Other types of parallax lenses are known. For example, lenticular lens arrays can be used to directionally interleave images in different directions to form a stereoscopic image pair or to form two or more images, each viewed in a different direction.

Holographic methods of image segmentation are known, but in practical applications these methods suffer from pseudoscopic regions of viewing angle and are not easy to control the image.

Another type of parallax barrier is a micropolarizer display, using a polarization-direction light source and patterned high-precision micropolarizer units aligned with the pixels of the SLM. The above display provides a high window image quality, a small device, the possibility to switch between a 2D display mode and a 3D display mode. The main requirement for using a micro-polarizer display as a parallax optic is that parallax problems need to be avoided when the micro-polarizer unit is incorporated with the SLM.

When a colour display is required, each pixel of the SLM4 is typically given a filter associated with one of the three primary colours. By controlling the three-pixel set, with each pixel having a different color filter, many visible colors can be produced. In a self-stereoscopic display, each stereoscopic image channel must contain enough color filters to balance the color output. Many SLMs have color filters arranged in vertical columns, and because of ease of manufacture, all pixels in a given column have the same color filter associated with them. If the parallax optic is placed on such a SLM with three pixel columns associated with each slit or lens of the parallax optic, then only one pixel of color will be seen per viewing area. The arrangement of the color filters must be careful to avoid this. Further details of suitable color filter arrangements are given in EP-A-0752610.

The effect of the parallax optic in a directional display device such as that shown in figures 1 and 4 is to limit the transmission of light through the pixels of the SLM4 to certain output angles. This limit defines the viewing angle of each pixel column behind a given pixel (such as a transmissive slit) of the parallax optic. The viewing angle range of each pixel is determined by the pixel spacing p, the spacing s between the pixel plane and the parallax optic plane, and the refractive index n of the material (substrate 7 of the display in fig. 1) between the pixel plane and the parallax optic plane. H Yamamoto et al in IEEE Trans. Electron, volume E83-C, no.10, page 1632, "optimal parameters and viewing areas of stereoscopic full-color LED display using parallax barrier" discloses that the separation angle between images in an autostereoscopic display depends on the distance between the display pixels and the parallax barrier.

The half angle α in fig. 1 or 4 is given by the following formula:

one problem with many known multi-view directional displays is that the angular separation between the two images is too low. In principle, the angle 2 α between the viewing windows can be increased by increasing the pixel spacing p, decreasing the spacing s between the parallax optic and the pixels or by increasing the refractive index n of the substrate.

Pending UK patent application No.0315171.9 describes a new pixel structure for use in standard parallax barriers, providing greater angular separation in the viewing window of a multi-view directional display. However, it is desirable to be able to use standard pixel structures in multi-view directional displays.

Pending UK patent application nos. 0306516.6 and 0315170.1 suggest increasing the separation angle between the viewing windows of a multi-view directional display by increasing the effective pitch of the pixels.

JP-a-728015 suggests increasing the pixel pitch and thus increasing the angular separation between the viewing windows of a multi-view directional display by rotating the pixel configuration so that the color sub-pixels move in the horizontal direction rather than the vertical direction. This results in a three-fold increase in pixel width and thus a roughly three-fold increase in viewing angle. The disadvantage is that the spacing of the parallax barrier must increase as the pixel spacing increases, increasing the visibility of the parallax barrier to the viewer. The manufacture and operation of the non-standard panels described above is not cost effective. In addition, in some applications, increasing the viewing angle requires more than three times the standard configuration, and in this case, simply rotating the pixels is not sufficient. This is typically the case for high resolution panels.

However, in general, the pixel spacing is typically defined by the resolution specification required of the display device and therefore cannot be changed.

Changing the refractive index of substrates, which are usually made of glass, is not always practical or significantly cost effective.

Other attempts to increase the angular separation between the viewing windows of a multi-view directional display device have been to reduce the separation between the parallax optic and the pixel plane of the SLM. This is difficult, however, as will be described below with reference to fig. 5, which is a schematic block diagram of the display device 1 of fig. 1, in which the LCD serves as the SLM 4.

The LCD panel forming the SLM4 is made of two glass substrates. The substrate 6 carries TFT switching elements which are used to address the pixels of the SLM, hence the term "TFT substrate". Other layers, such as a collimating liquid crystal layer 8, are also typically carried, allowing electrical switching of the liquid crystal layer. The color filter 18 is formed in a further layer 7 (corresponding to the counter substrate in fig. 1) together with a further layer, for example a calibration liquid crystal layer. The reverse substrate 7 is therefore commonly referred to as a "color filter substrate" or CF substrate. The LCD panel is formed by placing a color filter substrate opposite to a TFT substrate and sandwiching a liquid crystal layer 8 between the two substrates. In previous directional displays, the parallax optic has been adhered to the entire LCD panel, as shown in fig. 5. The distance between the LCD pixels and the parallax optic is determined primarily by the CF substrate thickness of the LCD. Reducing the CF substrate thickness will reduce the distance between the LCD pixels and the parallax optic, but will correspondingly make the substrate less durable. The practical minimum value of the LC substrate thickness is about 0.5mm, but if the parallax mirror is adhered to a substrate of this thickness, the pixel to parallax mirror separation is still too large for many applications.

Japanese patent No.9-50019 discloses a method of increasing the angular separation between the viewing windows of a multi-view directional display device, thereby reducing the viewing distance. This patent suggests reducing the thickness between the LC and the separator. This is achieved by constructing the stereoscopic LCD panel in the following order: LCD panel, parallax barrier, and polarizer. The previous sequence: LCD panel, polarizer, parallax barrier as shown in figure 1. This reduces the separation between the parallax barrier and the pixel plate by the thickness of the polarisers, but this results in only a limited increase in the angular separation between the viewing windows of a multi-view directional display device.

GB2278222 discloses a spatial light modulator with an array of microprisms placed near the liquid crystal layer to prevent the occurrence of a second sequential image at high angle incidence.

GB2296099 discloses a spatial light modulator with cells such as polarisers and half-wave plate 32 placed between two substrates of the spatial light modulator. This avoids the use of highly isotropic substrates so that cheaper and lighter plastic substrates can be used. If the polariser is placed outside the spatial light modulator, the substrate of the spatial light modulator must be highly isotropic in order to prevent the substrate from causing the polarisation direction of light passing through the substrate to change.

US-se:Sup>A-5831765 discloses se:Sup>A directional display with se:Sup>A liquid crystal panel and se:Sup>A parallax barrier. The parallax barrier is not placed inside the liquid crystal panel, and is outside the liquid crystal panel, separated from the liquid crystal layer by the diffuser, as it is through the substrate of the liquid crystal panel.

US-se:Sup>A-4404471 discloses se:Sup>A lenticular film using x-rays. Mercury, graphite or tungsten powder, or other flowable x-ray absorbing material is introduced into the grooves of the x-ray transmissive material.

Disclosure of Invention

The invention provides a multi-view directional display having an image display unit and a parallax optic, wherein the image display unit comprises: a first substrate; a second substrate; an image display layer sandwiched between the first substrate and the second substrate; wherein the parallax optic is mounted within the image display unit.

The parallax optic is within the image display unit such that the parallax optic is closer to the image display layer, thus reducing the spacing s in equation (1) and increasing the angular separation between the two viewing windows produced by the display device. It is not necessary to reduce the thickness of one substrate of the image display unit, and thus the structural strength of the image display unit is not affected.

The display of the present invention is intended to use light in the visible region of the spectrum so as to display an image in the visible region of the spectrum and visible to a viewer.

The parallax optic may be mounted between the first and second substrates. This is a known method of bringing a parallax optic close to an image display layer.

Alternatively, the parallax optic may be mounted within one of the first substrates or the second substrate. This is another method of bringing the parallax mirror closer to the image display layer without reducing the substrate thickness of the image display unit.

Optionally, the parallax optic may be mounted within the thickness of the first substrate.

The parallax optic may comprise a plurality of parallax elements, each parallax element being mounted in a respective recess in the major surface of the first substrate.

The first substrate may include a base substrate and a light transmitting layer mounted on the base substrate, and the parallax lens is mounted between the light transmitting layer and the base substrate.

The first substrate includes: a base substrate; a light-transmitting layer mounted on a main surface of the base substrate; a plurality of grooves defined in the light transmissive layer, and the parallax optic may comprise a plurality of parallax elements, each parallax element being mounted in a respective groove of the light transmissive layer.

Each parallax element may be mounted on a bottom surface of the respective groove.

The cross-section of the groove parallel to the surface of the substrate may decrease with increasing depth.

Each parallax element may substantially fill a respective groove.

A color filter array or a transformation element array may be mounted on a major surface of the first substrate.

The display may further comprise a light transmissive layer mounted between the parallax optic and the color filter array or the array of conversion cells.

The display may further comprise another parallax optic mounted between the parallax optic and the color filter array or the array of transform elements.

A color filter array or a transform element array may be mounted on the second major surface of the first substrate.

The light transmissive layer may be installed between the parallax glass and the image display layer.

The parallax optic and one of the color filter array and the transform unit array may be mounted on a major surface of a base substrate, the base substrate being contained within the first or second substrate.

The parallax mirror may be mounted on the first major surface of the base substrate, and the color filter array or the transform unit array is mounted on the parallax mirror.

The color filter array or the transform unit array may be mounted on the first major surface of the base substrate, and the parallax mirror may be mounted on the color filter array or the transform unit array.

The light transmissive layer may be installed between the parallax optic and the color filter array or the transforming unit array.

The parallax optic may comprise a plurality of parallax elements, each parallax element being mounted in a respective recess in the major surface of the first or second substrate.

The second light transmitting layer may be mounted to a major surface of the base substrate between the base substrate and the first light transmitting layer; the plurality of grooves can be defined in the second light-transmitting layer; the parallax optic may comprise a plurality of parallax elements, each parallax element being mounted in a respective recess in the second light transmitting layer (32).

One of the color filter array and the transform unit array may be mounted on a first major surface of a base substrate, and the parallax optic is mounted in or on a second major surface of the base substrate, the base substrate being included in the first or second substrate.

The parallax optic may comprise a plurality of parallax units, each parallax unit being mounted in a respective groove in the second major surface of the base substrate.

Each parallax element may be mounted on the bottom surface of the respective groove.

The cross-section of the groove parallel to the surface of the substrate may decrease with depth.

Each parallax element may substantially fill a respective groove.

The light-transmitting layer may be a transparent resin layer, a laminated plastic layer or a glass layer.

The parallax optic may be a parallax barrier or a lenticular lens array.

The parallax lenses may be disabled and addressable.

A second aspect of the invention provides a dual view display device comprising a multi-view directional display device as defined above.

A third aspect of the invention provides a self-contained display device comprising a multi-view directional display device as defined above.

A fourth aspect of the present invention provides a parallax optic comprising: the parallax-cell array comprises a light-transmitting substrate and a plurality of parallax cells, wherein each parallax cell is arranged in a respective groove on the surface of the substrate.

The parallax lenses of the present invention are intended to use light in the visible region of the spectrum.

The cross-section of the groove parallel to the substrate surface may decrease with depth.

Each parallax element may substantially fill a respective groove.

A fifth aspect of the present invention provides a method of manufacturing a display device, comprising the steps of: (a) Reducing a thickness of a first substrate of an image display unit, the image display unit including the first substrate, a second substrate, an image display layer mounted between the first substrate and the second substrate; and (b) adhering a third substrate to the first substrate with the parallax optic mounted between the two substrates.

The third substrate may be directly adhered to the first substrate or, alternatively, one or more other components may be interposed between the first substrate and the third substrate.

The parallax lens may be defined on or within the first major surface of the third substrate, and step (b) may include adhering the first major surface of the third substrate to the first substrate of the image display unit.

Drawings

Preferred embodiments of the present invention will be described with reference to the embodiments in the drawings, in which:

FIG. 1 is a schematic plan view of a known free-standing display device;

fig. 2 is a schematic view of a viewing window provided by a known multi-view display device;

FIG. 3 is a schematic plan view of a viewing window produced by another known multi-view directional display device;

FIG. 4 is a schematic plan view of another known free-standing display device;

FIG. 5 is a schematic plan view depicting a principal part of a known multi-view directional display device;

FIGS. 6 (a) and 6 (b) depict a display according to a first embodiment of the present invention;

FIGS. 6 (c) and 6 (d) illustrate a display according to another embodiment of the present invention;

FIGS. 7 (a) and 7 (b) depict a display according to another embodiment of the present invention;

FIGS. 8 (a) and 8 (b)) depict a display according to another embodiment of the present invention;

FIGS. 9 (a) and 9 (b) depict a display according to another embodiment of the present invention;

FIGS. 10 (a) and 10 (b) depict a display according to another embodiment of the present invention;

FIGS. 11 (a) and 11 (b) illustrate a display according to another embodiment of the present invention;

FIGS. 12 (a) and 12 (b) depict a display according to another embodiment of the present invention;

FIGS. 13 (a) and 13 (b) depict a display according to another embodiment of the present invention;

FIGS. 14 (a) and 14 (b) depict a display according to another embodiment of the present invention;

FIGS. 14 (c) and 14 (d) illustrate a display according to another embodiment of the present invention;

FIGS. 15 (a) and 15 (b) depict a display according to another embodiment of the present invention;

FIGS. 15 (c) and 15 (d) illustrate a color filter substrate for a display according to another embodiment of the present invention;

FIGS. 16 (a) and 16 (b) depict a display according to another embodiment of the present invention;

FIGS. 17 (a) and 17 (b) depict a display according to another embodiment of the present invention;

FIGS. 18 (a) and 18 (b) depict a display according to another embodiment of the present invention;

FIGS. 19 (a) and 19 (b) depict a display according to another embodiment of the present invention;

FIGS. 20 (a) and 20 (b) depict a display according to another embodiment of the present invention;

FIGS. 20 (c) and 20 (d) illustrate a color filter substrate for a display according to another embodiment of the present invention;

FIGS. 21 (a) and 21 (b) illustrate a display according to another embodiment of the present invention;

FIGS. 21 (c) and 21 (d) illustrate a color filter substrate for a display according to another embodiment of the present invention;

FIG. 22 depicts a display according to another embodiment of the invention;

FIG. 23 depicts a display according to another embodiment of the invention;

FIG. 24 depicts a display according to another embodiment of the invention;

FIG. 25 depicts a display according to another embodiment of the invention;

FIGS. 26 (a) to 26 (d) illustrate a method of manufacturing a display of the present invention;

FIG. 27 depicts a display according to another embodiment of the invention;

FIG. 28 depicts a display according to another embodiment of the invention;

FIG. 29 depicts a display according to another embodiment of the invention;

FIG. 30 depicts a display according to another embodiment of the invention;

FIG. 31 depicts a backlight suitable for use in the display of the present invention;

FIG. 32 depicts another backlight suitable for use in a display of the invention;

FIG. 33 depicts another backlight suitable for use in a display of the invention;

FIG. 34 depicts another backlight suitable for use in the display of the present invention.

Like reference symbols in the various drawings indicate like elements.

Detailed Description

Fig. 6 (b) is a schematic plan view of a multi-view directional display according to a first embodiment of the present invention. The display device 58 comprises a first transparent substrate 6 and a second transparent substrate 7, with an image display layer 8 mounted between the first substrate 6 and the second substrate 7. The color filter array 18 is provided on a second substrate 7, which is therefore referred to as a color filter substrate.

The first substrate 6 is provided with pixel electrodes (not shown) for defining an array of pixels in the image display layer 8, while switching elements (not shown), such as Thin Film Transistors (TFTs), are provided for selectively addressing the pixel electrodes. The substrate 6 will be referred to as a "TFT substrate".

The image display layer 8 is a liquid crystal layer 8 in this embodiment. The invention is not limited thereto and thus any transmissive image display layer may be used. Furthermore, the display is used in a "front barrier mode", i.e. the parallax mirror is mounted between an image display layer, which may be an emissive display layer such as a plasma display or an Organic Light Emitting Device (OLED) layer, and a viewer.

The display 58 is assembled such that each color filter 18 is substantially opposite one pixel of the image display layer 8. Other components such as alignment layers may be mounted on the surface of the

substrate

6,7 adjacent to the image display layer, and the counter electrode or electrodes may be mounted on the CF substrate 7; these components are known and will not be described further. Moreover, the display 58 may include further components such as polarizers, viewing angle enhancement films, anti-reflective films, etc., mounted on the exterior of the image display unit; these components are also known and will not be described further.

The color filter substrate 7 is shown in more detail in fig. 6 (a). The color filter substrate 7 comprises a basic substrate 19, which is made of a light-transmitting material, such as glass. The parallax barrier slit array 13 is mounted on one main surface of the base substrate 19. In the embodiment of figure 6 (a) the parallax barrier slit array 13 is formed by depositing opaque bands 14 on the surface of a base substrate, thereby defining transmissive slits 15 between the opaque bands.

The color filter substrate further includes a spacer layer 20, formed of a light-transmitting resin in the present embodiment, provided on the parallax barrier slit array 13. The parallax barrier slit array is mounted inside the substrate 7. Finally, a color filter 18 is mounted on the upper surface of the spacer layer 20.

In the present embodiment, the parallax barrier slit array 13 is separated from the pixels of the liquid crystal layer 8 by the thickness of the resin separation layer 20. The resin layer 20 can be made very thin so that the spacing s in equation (1) is small, resulting in a large angular spacing of the viewing windows. Although the resin layer 20 is shown as a single layer, in practice two or more separate resin layers may be deposited to obtain a separation layer of the desired thickness. For example, layer 20 may have a thickness of 50 microns and may include polyethylene phthalate (perephthalate).

Fig. 6 (d) is a schematic plan view of a display 21 according to another embodiment of the present invention, and fig. 6 (c) shows an opposite substrate of the display. Only the differences between this embodiment and the previous embodiment will be described.

In this embodiment, both the parallax barrier slit array 13 and the color filter 18 are mounted on the first main surface of the base substrate 19 of the color filter substrate 7'. A partition layer 20 of a color filter substrate, also formed of resin, is mounted on the parallax barrier slit array 13 and the color filter array. Thus, the parallax barrier slit array is mounted within the thickness of the substrate 7'. The parallax barrier slit array 13 is separated from the pixels of the liquid crystal layer 8 by the thickness of the resin layer 20, which can be very small. The color filter array is similarly separated from the liquid crystal layer 8 where no additional color filter array is required. Providing the parallax barrier and the colour filters in the same plane simplifies the manufacture of the display.

The resin layers 20 of fig. 6 (a) to 6 (d) are easily manufactured to have the same thickness. The layers may be deposited by, for example, spin coating or printing.

Fig. 7 (b) is a plan view of a display 22 according to a further embodiment of the present invention, and fig. 7 (a) shows a color filter substrate of the display 22. Only the differences between this embodiment and the first embodiment will be described.

In the embodiment of fig. 7 (a) and 7 (b), the parallax barrier slit array 13 is deposited on a major surface of a base substrate 19. The color filter substrate 7 further comprises a spacer layer 20 on the parallax barrier slit array 13, and the color filter array is mounted on the spacer layer 20. Thus, the parallax barrier slit array is mounted within the thickness of the color filter substrate 7. In this embodiment, the spacer layer 20 is a glass spacer layer rather than a resin spacer layer. A glass spacer layer is adhered to the parallax barrier and may be etched to a desired thickness.

The use of the glass layer 20 simplifies further processing steps. For example, when the transmissive layer is a glass layer, color filter 18 is fabricated on transmissive layer 20 as a color filter fabricated on a common glass substrate.

Fig. 8 (b) is a schematic plan view of a display 23 according to another embodiment of the present invention, and fig. 8 (a) shows a CF substrate of the display. The display 23 of the present embodiment generally corresponds to the display of fig. 6 (b), and only the differences between the embodiments will be described. In the display 23, the separation layer 20 between the parallax barrier slit array and the colour filter array 18 is a layer of plastics material. The layer of plastics material is adhered to the parallax barrier slit array 13 by a suitable method such as lamination or gluing. The plastic material 20 may optionally be printed onto the parallax barrier slit array.

Using laminated plastic layers as the transmissive layer 20 is less expensive than using spin coating techniques to form a resin light-transmissive layer. There is also less waste of material than using resin and the lamination process is faster.

Fig. 9 (b) is a schematic plan view of a multi-view directional display 24 according to another embodiment of the invention, and fig. 9 (a) shows a CF substrate 25 of the display. The display 24 also includes a TFT substrate 6, a color filter substrate 25, and a liquid crystal layer or other image display layer 8 mounted between the TFT substrate 6 and the color filter substrate 25.

Fig. 9 (a) shows a color filter substrate 25 of a display. As can be seen, a plurality of grooves 26 are formed in the first major surface of the base substrate 19. The base substrate 19 may be formed from any suitable light transmissive material such as glass, plastic or glass reinforced plastic. The grooves 26 may be formed by any suitable process, such as an etching or cutting process. The recess 26 is preferably a slot extending substantially the entire vertical height of the base 19, that is, extending into the plane of the paper of figure 9 (a). The grooves 26 preferably have substantially the same depth and width as each other.

A parallax barrier slit array is defined in the base substrate 19 by depositing an opaque material into each groove 26 so as to cover at least the bottom surface of each groove. The opaque material thus defines opaque bands 14 of the parallax barrier slit array, with the light transmissive regions defined between the opaque bands 14. The opaque band 14 and the array of parallax barrier slits are mounted within the thickness of the substrate 25.

The opaque material forming the opaque regions of the parallax barrier slit array may be any suitable opaque material and may be deposited by any suitable method. For example, opaque resin may be deposited in the grooves 26 by a spin process.

Once the opaque material has been deposited, the recesses are then filled with a light-transmissive material in order to planarize the surface of the base substrate 19. For example, the light-transmissive resin may be deposited in the groove 26 by a spin process.

Once the surface of the base substrate 19 has been flattened, the color filter array 18 may be deposited onto the base substrate 19, completing the color filter substrate 25.

In this embodiment the separation between the parallax barrier slit array and the liquid crystal layer is approximately equal to the depth d of the groove 26. The depth d of the grooves may be small, for example 50 microns, in order to obtain a large angular separation between the viewing windows.

Fig. 10 (b) shows a display 27 according to another embodiment of the invention. The display 27 includes a TFT substrate 6, a color filter substrate 25', and a liquid crystal layer (or other image display layer) 8 mounted between the TFT substrate 6 and the color filter substrate 25'. This embodiment corresponds substantially to the embodiment of fig. 9 (a) and 9 (b)), and only the differences between the two embodiments will be described.

Fig. 10 (a) is a schematic plan view of the color filter substrate 25' of the display 27. In this embodiment, the color filter 18 is deposited on a first major surface of a base substrate 19. A recess 26 is defined in the second major surface of the base substrate 19, for example using etching or cutting techniques. An opaque material is then deposited into the grooves to form opaque bands 14 of the parallax barrier slit array. The opaque band 14 and the parallax barrier slit array are mounted within the thickness of the substrate 25. The recesses may then be filled with a light transmissive material, if desired, to planarize the second major surface of the base substrate 19. As with the previous embodiments, any suitable material may be deposited as the opaque material, and may be deposited by any suitable technique. In a preferred embodiment, the opaque resin may be deposited in the grooves 26 by a spin-on technique.

The spacing between the parallax barrier and the liquid crystal layer is reduced by the depth of fewer grooves, for example 50 microns, compared to the known display of figure 5, so that the angular spacing between the viewing windows is increased accordingly. Since the thickness of the base substrate is reduced only at the location of the grooves, the structural strength of the base substrate is greater than if the entire substrate had a reduced thickness.

Fig. 11 (b) is a schematic plan view of a multi-view directional display 28, according to another embodiment of the invention. The display includes a TFT substrate 6, a color filter substrate 29, and a liquid crystal layer 8 or other image display layer mounted between the TFT substrate 6 and the color filter substrate 29.

The color filter substrate 29 is shown in fig. 11 (a). As can be seen, the color filter substrate 29 is substantially identical to the color filter substrate 7 of fig. 6 (a), except that it provides two parallax barriers 13, 13'. The color filter substrate 29 comprises a base substrate 19, which may be made of any suitable light-transmissive material, such as glass. A first parallax barrier slit array 13 is mounted on the base substrate first surface. The parallax barrier slit array may be formed by, for example, depositing a strip of opaque material 14 on the substrate to form the opaque parts 14 of the parallax barrier slit array 13.

A first light transmissive spacer layer 20 is then deposited onto the surface of the substrate 19 with an array of parallax barrier slits formed in the substrate 19. The first spacer layer may be formed of, for example, a light-transmissive resin, glass or a transparent plastics material, as described above with reference to the embodiment of figures 6 (a), 7 (a), 8 (a).

A second parallax barrier slit array 13' is mounted on the upper surface of the first separating layer 20. The second parallax barrier slit array may also be formed by depositing an opaque material on the spacer layer 20 so as to form the opaque parts 14' of the second parallax barrier slit array.

The color filter substrate further comprises a second separator layer 20' on the second parallax barrier slit array. The parallax barrier slot arrays 13, 13' are both mounted within the thickness of the substrate 29. The second spacer layer may also be any suitable transparent material such as a light-transmissive resin, a glass layer, glass or a transparent plastic material.

A color filter 18 is deposited on the upper surface of the second separator layer 20'.

The two parallax barriers 13, 13 'are arranged so that the transmissive region of the second barrier 13' is not directly mounted in front of the transmissive region of the first parallax barrier 13. The two parallax barriers are arranged such that the transmissive regions of the second parallax barrier 13' are aligned with the opaque regions 14 of the first parallax barrier 13, and thus the opaque regions 14' of the second parallax barrier 13' are aligned with the transmissive regions of the first parallax barrier 13. Thus, light from the backlight is blocked by one of the parallax barriers 13, 13' in a direction parallel to or close to the normal of the display surface of the display. Since the two parallax barriers are arranged such that the transmission region of the first parallax barrier 13 is laterally offset from the transmission region of the second parallax barrier 13', light from the second parallax barrier 13' travels in the first and second direction ranges inclined with respect to the normal.

Many backlights have a maximum brightness along the vertical axis, which is disadvantageous in multi-view directional displays because the viewing window is typically positioned at an angle to the vertical axis. In a typical dual view display, the two viewing windows may be positioned ± 40 degrees of normal. Using two parallax barriers as in the display of fig. 11 (b) provides a "black central window", that is, the lowest brightness in the region centered on the normal to the display surface of the display.

This embodiment is not limited to providing two parallax barriers on the color filter substrate. In principle, three or more parallax barrier slit arrays may be provided on the substrate 19, with each pair of adjacent parallax barrier slit arrays being separated by a respective separation layer.

In the embodiment of fig. 11 (a), the two separation layers 20, 20' need not be formed of the same material. The two separation layers may be made of different materials, and thus, as an example, the first separation layer 20 may be a glass layer, but the first separation layer 20' may be a light-transmitting resin layer.

In another embodiment (not shown) the colour filter substrate comprises two parallax barrier slit arrays mounted on each side of the base substrate 19. In this embodiment, a first parallax barrier array is formed on one main surface of the base substrate 19, a filter 18 is provided in the first parallax barrier array, and a light-transmitting separation layer is provided between the first parallax barrier slit array and the filter 18, as shown in fig. 6 (a), 7 (a) or 8 (a). A second parallax barrier slit array is formed on the second main surface of the base substrate 19, covered with a light-transmissive layer, so that the two parallax barrier slit arrays fit within the thickness of the color filter substrate.

Fig. 12 (a) and 12 (b) show another embodiment according to the present invention. Fig. 12 (b) is a schematic plan view of a multi-view directional display 30 according to an embodiment of the present invention. The display device also includes a TFT substrate 6, a color filter substrate 31, and a liquid crystal layer 8 or other image display layer mounted between the TFT substrate 6 and the color filter substrate 31.

Fig. 12 (a) is a schematic plan view of a color filter substrate 31 of an embodiment of the present invention. The color filter substrate 31 comprises a base substrate 19, which may be made of any suitable light-transmissive material. A plurality of grooves 26 are defined in one surface of the substrate 19 by any suitable process such as etching or gouging. When the base 31 is shown in a front view, the grooves 26 look like parallel bands from the top to the bottom of the base 19.

As shown in fig. 12 (a), in this embodiment, the width of the groove parallel to the surface of the substrate 19 gradually decreases as the distance from the substrate increases. In the embodiment of fig. 12 (a), the grooves 26 have a triangular cross-section, but the grooves are not limited to this particular cross-section.

The parallax barrier slit array 13 is formed by depositing an opaque (or reflective) material (or both) in the recess 26 to form the opaque parts 14 of the parallax barrier slit array. The opaque material preferably fills the recess 26 sufficiently to planarize the upper surface of the base substrate 19. In the preferred embodiment, the opaque material is an opaque resin that is deposited in the grooves 26 by a spin process, however, in principle any opaque material may be used.

The color filter substrate 31 further includes a light-transmissive spacer layer 20 deposited on the upper surface of the base substrate 19. The parallax barrier slit array is thus mounted within the thickness of the substrate 31. As described above, the light-transmitting spacer layer 20 may be a light-transmitting resin layer, a glass layer, a light-transmitting plastic material layer, or the like. The spacer layer is adhered to the substrate 19 in any suitable manner.

Finally, the color filter 18 is deposited on the upper surface of the spacer layer 20 to form a color filter substrate 31.

In this embodiment, the parallax barrier has a three-dimensional cross-sectional view, since the opaque elements 14 of the parallax barrier slit array continue to a defined depth, for example 50 microns, to the substrate. The parallax barrier functions in the same way as known parallax barriers, such as the parallax barrier of figure 6 (a). However, due to the three-dimensional structure of the parallax barrier, light incident on the parallax barrier at a large angle to the normal to the plane of the substrate 19 is blocked, although the light can be transmitted by the known parallax barrier shown in fig. 6 (a). This is advantageous for blocking the second window.

In the color filter substrate of fig. 12 (a), the depth of the groove can be varied at the substrate 19 to vary the depth of the opaque part of the parallax barrier. This means that the shading angle at which light is blocked, relative to the normal to the plane of the substrate, will be changed by the display device.

Fig. 13 (a) shows another color filter substrate 31 'of the present invention, and fig. 13 (b) shows the color filter substrate of fig. 13 (a) in a display 30'. These embodiments are generally the same as the embodiments of fig. 12 (a) and 12 (b), respectively, and only the differences will be described hereinafter.

In the color filter substrate 31' of fig. 13 (a), the groove 26 is not formed on the base substrate 19. In contrast, the color filter substrate includes a light-transmitting spacer layer 32 on the base substrate 19, and the recess 26 is formed in the spacer layer 32. Spacer layer 32 may be any suitable material such as a light transmissive resin, glass, or a light transmissive plastic material. The recess 26 may be formed in the spacer layer 32 by any suitable method, such as cutting or etching.

Opaque material is deposited in the grooves 26 of the separating layer 32 to form the opaque parts 14 of the parallax barrier slit array, as described in figure 12 (a) above. Finally, the second spacer layer 20 is deposited on the first spacer layer 32, and the color filter 18 is formed on the upper surface of the second spacer layer 20. The parallax barrier slit array is thus mounted within the thickness of the substrate 31'.

In the above embodiments, the parallax optic is comprised of an array of parallax barrier slits. However, the present invention is not limited to the above specific form of the parallax glass, and other parallax glasses may be used.

Fig. 14 (a) and 14 (b) illustrate another embodiment of the present invention in which the parallax optic is formed of a lenticular lens array.

Fig. 14 (b) is a schematic plan view of a multi-view directional display in accordance with an embodiment of the present invention. The display 33 also includes a TFT substrate 6, a color filter substrate 34, and a liquid crystal or other image display layer 8 mounted between the color filter substrate 34 and the TFT substrate 6.

Fig. 14 (a) shows a color filter substrate 34 of a display device 33. The color filter substrate 34 comprises a light-transmissive base substrate 19 whose upper surface is profiled to form a lenticular lens array 35. The base substrate 19 may be formed in any suitable manner, such as by moulding a light-transmitting plastics material using a suitable mould to provide the lenticular lens array 35 on one surface of the base substrate 19. Alternatively, the lens array 35 may be formed by pressing a glass substrate.

The color filter substrate further includes a spacer layer 20 deposited on the lenticular array 35, the spacer layer being light-transmissive and preferably formed of a resin or plastic material so that a lower surface of the spacer layer can follow the contour of the lenticular array 35. The color filter 18 is deposited on the upper surface of the spacer layer 20, preferably flat. The lens array is thus mounted within the thickness of the substrate 31.

In this embodiment, the spacing between the parallax barrier (lenticular array 35) and the liquid crystal layer 8 is equal to the thickness of the spacer layer 20 and must be thick to at least planarize the prisms. The separation layer 20 can be very thin so that a large angular separation between the viewing windows can be obtained.

Fig. 14 (c) and 14 (d) show another embodiment of the present invention. Fig. 14 (c) shows another substrate 34a of the present invention. The substrate 34a includes a first light-transmissive substrate 19 having a surface for forming a first lenticular lens array 35. The substrate 34a further includes a second light transmissive substrate 19a having a surface that is sectioned to form a second lenticular lens array 35a. The light transmissive substrate 35, 35a may be formed in any manner, for example using one of the methods described above with reference to fig. 14 (a).

The light-transmissive substrate is mounted on the surface and the lens arrays are formed opposite to each other as shown in fig. 14 (c). A transparent spacer layer 20 is mounted between the two lenticular lens arrays 35, 35a, the spacer layer 20 being, for example, a transparent resin layer or a transparent adhesive layer. The two lenticular lens arrays 35, 35a are adjacent to each other and combine to give a greater power than a lens array having only one curved surface, such as the lens array of figure 14 (a). Both lens arrays are mounted within the thickness of the base 34a.

The color filter array 18 is mounted on an outer surface of the substrate 34a, which is preferably flat.

Fig. 14 (d) shows a display 33a comprising the substrate 34a of fig. 14 (c), an image display layer 8 such as a liquid crystal layer, and a second substrate 6.

Fig. 15 (a) and 15 (b) show another embodiment of the present invention. This embodiment is substantially the same as the embodiment of fig. 14 (a) and 14 (b), and only the differences will be described.

In fig. 14 (a) and 14 (b), the lenticular lens array 35 is integral with the base substrate 19 and is obtained by profiling the upper surface of the base substrate 19. In the embodiment of fig. 15 (a) and 15 (b), the lenticular array 35' is not integral with the base substrate 19. However, the base substrate 19 has a substantially flat upper surface, and the lenticular lens array 35' is deposited on the upper surface of the base substrate 19. This may be accomplished by any suitable technique. For example, a light-transmissive resin layer or a light-transmissive plastic material layer may be deposited onto the upper surface of the base substrate 19, which layer may be processed to form the lenticular lens array 35'.

Fig. 15 (c) shows a CF substrate 34 "which is different from the substrate 34' in fig. 15 (a), and the lenticular lens array 34" is "bilateral". In other words, the lens array 35' is plano-convex and the lens array 35 "is bi-convex. Although the above arrangement is more difficult to manufacture because the recess must be formed in the substrate 19, the optical performance is improved. For example, a display using the substrate 34 "of FIG. 15 (c) has a smaller interference area and greater viewer freedom of movement.

Fig. 15 (d) shows another modified CF substrate 34  that differs from the substrate 34 "of fig. 15 (c) in that the lens array 34  is divided and separated by black mask regions 35". Indeed, any embodiment using a lens array as a parallax barrier may equally have a single lens or lens elements separated by black masking regions which are not transmissive to visible light.

The f-number requirement of the lenticular array is low, making the array difficult to manufacture. By reducing the diameter of each lens in the array and keeping the pitch constant (by filling the gaps between the lenses with a light absorbing material or a light reflecting material or both), the f-number of the lenses can be increased. The arrangement described above improves performance, for example, in providing a smaller interference area and greater freedom of viewer position.

Fig. 16 (a) and 16 (b) show another embodiment of the present invention. Fig. 16 (b) is a schematic plan view of a multi-view directional display 37 of the present invention, and fig. 16 (a) is a schematic plan view of a color filter substrate 36. This embodiment is substantially the same as the embodiment of fig. 6 (a) and 6 (b), and only the differences will be described here.

In the embodiment of fig. 16 (a) and 16 (b), the positions of the parallax barrier slit array 13 and the color filter 18 are interchanged as compared with those in the embodiment of fig. 6 (a) and 6 (b). That is, the color filter 18 is deposited on the main surface of the light-transmitting base substrate 19. A spacer layer 20 is deposited on the color filter 18 and a parallax optic is formed on the upper surface of the spacer layer 20. In the embodiment shown in fig. 16 (a) and 16 (b), the parallax barrier slit array 13 forms a parallax mirror, but the embodiment is not limited to this particular parallax mirror. The spacer layer 20 may be a light-transmitting resin layer, a glass layer, a light-transmitting plastic material layer, or the like.

In the embodiment of fig. 16 (a) and 16 (b)), the parallax barrier array 13 is mounted adjacent the liquid crystal layer 8. A large angular separation between the different viewing windows can thus be obtained.

Fig. 17 (a) and 17 (b)) depict a display 38 according to another embodiment of the present invention. In this embodiment, the parallax optic is comprised of a reactive mesogen (reactive media) parallax barrier. This embodiment corresponds substantially to the embodiment of fig. 6 (a) and 6 (b)), and only the differences are described here.

The RM parallax barrier in this embodiment is formed by a strip of reactive medium (reactive media) material 40 mounted on the upper surface of the light transmissive base substrate 19 of the colour filter substrate 39. A polariser 41 is mounted on the upper surface of the base substrate 19 comprising the ribbon of RM material 40. The RM material strip 40 and the polarisers 41 form RM parallax barriers 42. The operation of RM parallax barriers is explained in detail in EPA 0829744.

The color filter substrate 39 further includes a spacer layer 20 deposited on the upper surface of the RM parallax barrier 42 so that the parallax barrier 42 fits within the thickness of the substrate 39. A color filter 18 is deposited on the upper surface of the spacer layer 20. As in the previous embodiments, the spacer layer 20 may be, for example, a light-transmissive resin layer, a glass layer, a light-transmissive plastic layer, or the like. The base substrate 19 may be a glass substrate, a plastic substrate, a glass-reinforced plastic substrate, or the like.

In the multi-view directional display 38 of this embodiment, the spacing between the parallax barrier 42 and the liquid crystal layer 8 is approximately equal to the thickness of the separation layer 20. The separation layer may be thin in order to obtain a good angular separation between the different viewing windows.

Another advantage of this embodiment is that the RM parallax barrier is an active parallax barrier and can be switched (using suitable addressing means, not shown) so that the RM material strips 40 are in a transparent state so that the RM parallax barrier is not available or "broken". If the parallax barrier 42 is disabled, the display device will function as a conventional two-dimensional or single view display device. Thus, this embodiment provides a display that operates in either a 2-D display mode or a 3-D or multi-view display mode and may provide good angular separation between adjacent viewing windows when operating in the 3-D or multi-view display mode.

Fig. 18 (b) depicts a display 38 'according to another embodiment of the invention, and fig. 18 (a) is a schematic cross-sectional view of a color filter substrate 39' of the display. The display 38' of this embodiment corresponds substantially to the embodiment of figures 17 (a) and 17 (b) except that the spacer layer 20 is omitted and the colour filter 18 is mounted directly on the upper surface of the polariser 42. All other features of the display 38' of fig. 18 (b)) correspond to those of the display 38 of fig. 17 (b)) and are therefore not described further.

Fig. 19 (a) and 19 (b) show another embodiment of the present invention. In this embodiment the color filter substrate 44 of the multi-view directional display 43 has active parallax barriers 46. Fig. 19 (b) is a schematic plan view of the display device 43, and fig. 19 (a) is a schematic cross-sectional view of the color filter substrate 44.

The active parallax barrier 46 is formed by mounting a plurality of material regions 47, the optical characteristics of which are switchable, on the surface of the base substrate 19. The region 47 may be in the form of a strip which extends into the plane of the paper of figure 19 (a). An active parallax barrier is formed by combining a region 47 with another layer 45 mounted on the region 47, the region 47 may be a linear polariser or a transparent spacer layer, depending on the material used for the active stripes 47.

In a preferred embodiment, region 47 is a region of liquid crystal material and layer 45 is a linear polarizer. It is well known that liquid crystal materials can be addressed such that linearly polarized light passes through it regardless of whether the plane of polarization is rotated or not. Preferably, the region 47 of liquid crystal material is switchable between a state in which the plane of polarisation of linearly polarised light is rotated by 90 ° and a state in which the plane of polarisation of linearly polarised light is not rotated. Thus, the regions 47 of liquid crystal material can be addressed and light passing through the regions 47 either transmitted by the linear polariser 45 (in the case of the regions 47 defining transmissive regions) or blocked by the linear polariser 45 (in the case of the regions 47 defining opaque regions).

The display 43 requires illumination from the color filter substrate side by polarized light from a light source emitting polarized light or a polarizer mounted in front of the light source. Alternatively, illumination may be provided from the TFT side in the case where another polarizer (not shown) must be mounted outside the color filter substrate.

If light that does not pass through the optical zone 47 of switchable optical properties (i.e. passes through the gap between adjacent active zones) is passed through by the polariser 45, a parallax barrier is formed when light passing through the zone 47 is blocked by the polariser; in this case, a 3-D or multi-view display mode is obtained. If the region 47 is switched such that light passing through the region 47 is transmitted by the polariser 45, no spacers are present and a 2-D or single view display mode is obtained.

In principle, it is also possible to arrange the transmission direction of the polarizer 45 and the polarization direction of the incident light such that light passing through the gaps between the regions 47 of liquid crystal material is blocked by the polarizer 45. In this case, when the region 47 rotates the polarization plane of incident light so that the incident light can pass through the polarizer 45, a parallax barrier is formed. However, when the region 47 is shifted so that light passing through the band 47 is blocked by the polariser 45, a dark display will be produced as all light is blocked by the polariser 45.

The active material region 47 is not limited to a liquid crystal material. Any material that can be addressed to change optical properties can in principle be used. For example, a polymer-dispersed liquid crystal material may be used as the active parallax barrier material. PDLC is known to consist of small droplets of liquid crystal material dispersed in a polymer matrix. The refractive index of the liquid crystal droplet can be changed, and if the refractive index of the liquid crystal droplet is the same as the refractive index of the polymer matrix, the PDLC will transmit light. However, if the liquid crystal material is transformed such that its refractive index is different from that of the polymer matrix, light passing through the PDLC will be scattered.

Another suitable material for an active parallax barrier is a dichroic guest-host (dichroic guest-host) material. This embodiment allows the parallax barrier to be switched on or off, thus allowing either a 3-D (or multi-view) or 2-D display mode to be selected. Further, the active parallax barrier 46 may be arranged so that the structures of the transmissive and opaque regions can be changed. For example, the active parallax barrier 46 may be transformed such that the opaque regions of the barrier move from one location to another. This effectively causes the barrier to be displaced through the area of the display device and will alter the position of the viewing window. Thus, in this embodiment, it is possible to control the position of the viewing window by appropriately addressing the active parallax barrier 46. This embodiment is particularly useful when combined with a viewer tracking device that tracks viewers of a display, since the position of the viewing window can be controlled in accordance with the position of the viewer as determined by the viewer tracking device.

It should be noted that in this embodiment, the polarizer 45 is included in the liquid crystal display unit. Polarizer 45 must be able to withstand the harsh processing conditions used in the manufacture of liquid crystal display panels. Known polarizers used outside of liquid crystal displays do not withstand the processing conditions well and therefore cannot be used. There may be the disadvantage that polarizers with a lower contrast than the known polarizers used outside the liquid crystal display have to be used. If this is the case, the polariser 45 may be orientated such that its low contrast affects the contrast of the parallax barrier or the contrast of the pixels of the liquid crystal layer 8.

When the polariser 45 is a spacer it can be processed so that it adjusts the liquid crystal material, for example the region 47, to have a particular alignment direction and pre-tilt angle. For example, the spacer layer may be covered with a polyimide layer (not shown), rubbed and/or exposed to ultraviolet light in known photo-alignment processes.

In alternative embodiments, the color filter may be mounted on the TFT substrate 6 or between the active parallax barrier 46 and the substrate 19.

Fig. 20 (b) shows a display 48 according to another embodiment of the invention, and fig. 20 (a) shows a color filter substrate 49 of the display. This embodiment corresponds generally to the embodiment of fig. 6 (a) and 6 (b) except that in this embodiment the colour filter substrate 49 of the multi-view directional display 48 comprises active parallax lenses 35". In this embodiment, the active parallax optic 35 "is an active lenticular lens array. The lenticular array can be switched between a mode in which there is substantially no lens effect (and hence no parallax optic present) and a mode in which there is lens effect (and hence a parallax optic is formed). The lenticular array 35 "is addressable by suitable addressing means (not shown).

For example, the lenticular layers (lenses) of the lenticular array may be made of liquid crystal material which is addressed by electrodes (not shown) mounted on opposite sides of the lenticular layers (lenses). The liquid crystal material is chosen so that its refractive index is as close as possible to that of the base substrate 19 for some applied voltage across the lens array. When an appropriate voltage is applied between the electrodes on opposite sides of the lenticular layer (lenses), the refractive index of the liquid crystal material of the lenticular layer (lenses) closely matches the refractive index of the spacer layer 20, and the lenticular layer (lenses) is substantially free of lens effect. However, by varying the applied voltage, the liquid crystal material of the lenslet-like layer(s) can be varied such that its refractive index is different from that of the substrate 19. The lenticular layers (lenses) thus act as lenses, thus forming parallax optic units.

The lenslet-like layers (lenses) 50 of the active lenticular lens array may be arranged as Graded Refraction (GRIN) or may be arranged as fresnel lenses.

Fig. 20 (c) shows a substrate 49, which is different from the substrate shown in fig. 20 (a) in that the glass substrate 19 is recessed so as to accommodate the active lenticular lens array 35 ″. In this arrangement, the refractive index of the active array substantially matches that of the substrate 19 in a single view or non-directional mode of operation.

Fig. 20 (d) shows a substrate 49 in which the lenses of the active array 35 "are biconvex, providing improved performance, such as a smaller cross-over area and greater freedom of movement for the viewer. In this case, in the single view mode of operation, the refractive index of the array 35 "should match the refractive index of the substrate 19 and spacer layer 20.

Fig. 21 (b) shows a display 48' according to another embodiment of the invention, and fig. 21 (a) shows a color filter substrate 49' of the display 48 '. This embodiment is substantially the same as the embodiment of fig. 20 (a) and 20 (b), and only the differences will be described here.

The multi-view directional display 48' of fig. 21 (b) has a color filter substrate 49' that includes an active lenticular array 35'. In this embodiment, the transformation of the lens array is obtained in different ways. In this embodiment, the lenticular layers (lenses) 50 are made of a liquid crystal material. However, the microstructure of the liquid crystal material is fixed and the liquid crystal material is not addressed during operation of the device.

The conversion of the lens array in this embodiment is obtained by exploiting the fact that the refractive index of the liquid crystal material is generally dependent on the polarization state of the light passing through it. The liquid crystal material of the lenticular layers (lenses) 50 is selected so that for light of one polarization state the refractive index of the liquid crystal material is substantially the same as the refractive index of the spacer layer 20. The liquid crystal material is therefore substantially free of lens effects for light of this polarization state. However, for another polarization state, in particular for a polarization state orthogonal to the first polarization state, the refractive index of the liquid crystal material will not match the refractive index of the spacer layer 20, so that the liquid crystal material has a lens effect for light of the second polarization state.

By changing the polarization state of the light entering the display 48, the liquid crystal lenticules 50 are switched on or off. This may be achieved by providing a polarization switch 51 which may change the polarization state of light passing through selected components of the polarization switch 51, for example by selecting one of two orthogonal linear polarizations. The polarization switch 51 may be composed of, for example, a liquid crystal cell, and follows the polarizer 51'.

Fig. 21 (c) depicts another substrate 49' in which the glass substrate 19 is recessed to accommodate the array 35". In this case, one index of refraction of the material of the array 35 "must substantially match the index of refraction of the glass substrate 19 so as to provide a single view mode of operation.

FIG. 21 (d) depicts another form of color filter substrate 49' in which both the spacer layer 20 and the glass substrate 19 are recessed to accommodate the lenticular array 35". In this case, one index of refraction of the material of the array 35 "is required to match the index of refraction of the spacer layer 20 and the glass substrate 19 in order to provide a non-directional or single view mode of operation.

Fig. 22 is a schematic cross-sectional view of a multi-view directional display 52, in accordance with another embodiment of the invention. In many respects is the same as the display 58 of figure 6 (b) except that a plurality of prisms 53 are provided on the outer surface of the base substrate 19 of the colour filter substrate 7. In fig. 22, the prism 53 has a triangular cross section. The prism 53 works in conjunction with the parallax barrier 13 within the display device. In use, the device is illuminated from behind the TFT substrate 6 so that the base substrate 19 of the colour filter substrate 7 forms the exit face of the display device. The prism structure changes the angle of separation between the left image and the right image sensed by the parallax barrier.

In the embodiment of fig. 22, the prisms are arranged such that they reduce the angular separation between the viewing windows of the different images.

Although the prism illustrated in fig. 22 has a triangular cross-section, the embodiment is not limited to prisms having a triangular cross-section. In principle, any prismatic structure that reduces the angle of separation between the two viewing windows may be used. Further, a prism having a triangular cross-section is used, and the prism does not have to have an equilateral triangular cross-section. Virtually any symmetrical or asymmetrical, converging or diverging element may be used, such as any application that matches a display.

The embodiment of fig. 22 may be used with a self-stereoscopic display device where the angular separation between the viewing windows for the left-eye and right-eye images requires a desired viewing distance on the display, and the separation between the left-eye and right-eye windows is equal to the distance between the eyes of a person.

Fig. 23 shows a display 52' according to another embodiment of the invention. The display 52' generally corresponds to that of figure 22 except that the prisms 53 on the surface of the base substrate 19 are intended to increase the separation angle between the two viewing windows.

Fig. 24 depicts a multi-view directional display 59 in accordance with another embodiment of the present invention. The display 59 of this embodiment corresponds generally to the display device 20 of figure 6 (b) except that it further comprises a variable means 54 for varying the angle between the two viewing windows produced by the device. The convertible means 54 can be converted between a state that has substantially no effect on the angular separation between the two viewing windows and another state that increases or decreases the angular separation between the two viewing windows. In this embodiment, the switchable device 54 comprises a plurality of light-transmissive prisms 53 mounted on the outer surface of the primary substrate 19 of the color filter substrate. Active layer 55 is mounted on prism 53 so as to planarize the prism. The active layer is contained by a transparent plate 56. The prism and the transparent plate may be formed of glass, transparent resin, transparent plastic material, or the like. The active layer 55 may include, for example, a liquid crystal layer. The liquid crystal layer is selected such that the index of refraction of the liquid crystal material matches the index of refraction of the prism 53 when no electric field is applied to the liquid crystal material. In this state, the prism has substantially no effect on the angular separation between the two viewing windows produced by the apparatus 54.

The variable device 54 further includes electrodes (not shown) allowing an electric field to be applied to the liquid crystal layer 55. By applying a voltage to the electrodes and thus applying an electric field through the liquid crystal layer, the refractive index of the liquid crystal material can be changed so as to be different from that of the prism 53. Light passing through the interface between the prism and the liquid crystal layer thus undergoes refraction. As a result, the angular interval between the two viewing windows formed by the display device is changed by the prism 53. This allows the display 59 to be switched between a dual-view display mode and a self-contained display mode.

The variable device 54 may allow the angular separation between the two viewing windows to be continuously controlled by continuously varying the electric field applied to the liquid crystal layer. This allows the angular separation between the two viewing windows to be adjusted to suit the particular use of the display device 54. This embodiment is particularly useful if information about the longitudinal separation between the display and the observer is available, for example from an observer tracking device, in the free-standing display mode the variable device 54 can control the angular separation between the left and right eye viewing windows so that the lateral separation of the observer remains equal to the separation between the eyes of the person.

Fig. 25 shows a multi-view directional display 57 according to another embodiment of the invention. The display 57 is substantially the same as that of figure 24 and only the differences will be described herein.

In the display 57 of fig. 25, switchable means 54 are mounted on the outer surface of the substrate 19 of the colour filter substrate 7 for varying the angular separation between the two viewing windows formed by the display including the prisms 53. The liquid crystal layer 55 is mounted on the prism 53, however, the microstructure of the liquid crystal layer is fixed as compared to the embodiment of fig. 24. Means for addressing the liquid crystal layer 55 are therefore not required.

The refractive index of the liquid crystal layer 55 depends on the polarization state of light passing through the liquid crystal layer. The liquid crystal layer is chosen such that its refractive index is substantially equal to the refractive index of the prism 53 for one polarization state. In this case, the light passing through the prism 53 undergoes substantially no refraction.

For light of another polarization state, for example the polarization state orthogonal to the first polarization state, the refractive index of the liquid crystal layer 55 is not equal to the refractive index of the prism 53. Thus, for light of the second polarization state, refraction occurs at the interface between the prism and the liquid crystal layer 55, resulting in a change in the angular separation between the two viewing windows formed by the display 57.

In this embodiment, the refractive effect can be switched on or off by appropriate selection of the polarization state of the light entering or leaving the panel. This can be achieved by providing a polarisation switch 51 and polariser 51' between the light source and the viewer. In fig. 25, a polarization switch 51 and a polarizer 51' are installed between the display device and the viewer, but may alternatively be installed between the light source and the display device. The polarization switch may be, for example, a liquid crystal cell.

The embodiments of fig. 24 and 25 may be effected by prismatic structures for increasing the angular separation between the viewing windows, as shown in fig. 23.

Fig. 26 (a) to 26 (d) illustrate a method of manufacturing a display of the present invention. The method takes as its starting point a known image display device 63 having an image display layer 8, such as a liquid crystal layer, mounted between two

substrates

60, 61, as shown in fig. 26 (a). The image display device 63 will comprise other components such as electrodes and conversion units for controlling the image display layer 8 and, in the case of a color image display device, color filters; all of which are known and are omitted from fig. 26 (a) -26 (d) for clarity of illustration.

According to the method of this embodiment, the thickness of one substrate 60 of the image display apparatus 63 is reduced, with an optimum thickness in the range of 50 μm to 150 μm. The thickness of the substrate 60 may be reduced by any suitable method, such as a mechanical grinding method or a chemical etching method. The substrate 60 thus becomes a thin transparent layer 60' as shown in fig. 26 (b). The thin transparent layer 60 'preferably has a substantially uniform thickness in the region of the layer 60'.

Next, another substrate 62 is adhered to the thin transparent layer 60 'so that the parallax lens 13 is installed between the thin transparent layer 60' and the other substrate. This can be conveniently achieved by providing the parallax optic on or in the surface of the other substrate and adhering the surface of the other substrate to the thin transparent layer 60'. For example, the parallax barrier slit array may be printed on the surface of another substrate, as shown in fig. 26 (c). Alternatively, a lenticular lens array or RM parallax barrier may be defined in/on the surface of the other substrate. Another substrate 62 may be adhered to the thin transparent layer 60' using a suitable transparent adhesive.

Another substrate 62 may be adhered directly to the thin transparent layer 60' as shown in fig. 26 (d). An optional component or components may be disposed between the further substrate 62 and the thin transparent layer 60', as will be described below with reference to fig. 28.

The resultant display is shown in fig. 26 (d) (the clear adhesive is omitted in fig. 26 (d) for clarity). The parallax barrier is separated from the image display layer 8 only by the thin transparent layer 60 '(and by the thickness of the transparent adhesive), which thin transparent layer 60' is obtained by reducing the thickness of the substrate. The parallax optic is thus close to the image display layer 8 so that the advantages described above are obtained.

In the method of fig. 26 (a) to 26 (d), when the thickness of the substrate 60 is reduced, the substrate 60 is incorporated into the display device 63. Other elements of display device 63 provide physical support for substrate 60 during and after the thickness reduction process. It is thus possible to reduce the thickness of the substrate 60 to 50 μm without a significant risk of substrate breakage. In contrast, if the thickness of the separation substrate is reduced, it is difficult to make the thickness less than 0.5mm without a significant risk of substrate breakage.

The method of fig. 26 (a) to 26 (d) may be used to manufacture a display 22 such as that shown in fig. 7 (b). As can be seen from fig. 26 (d) in comparison with fig. 7 (b), the other substrate 62 of fig. 26 (d) corresponds to the base substrate 19 of fig. 7 (b), and the thin transparent layer 60' (obtained by reducing the thickness of the substrate 60 of the image display unit 63) of fig. 26 (d) corresponds to the glass layer 20 between the parallax barrier 13 and the color filter substrate 18 of fig. 7 (b).

The method of fig. 26 (a) to 26 (d) may be used in the manufacture of displays in which the parallax optic is not a parallax barrier slit array. For example, a lens array or RM parallax barrier may be mounted on one surface of the other substrate 62, thus allowing the manufacture of a display such as that shown in fig. 15 (b) or 17 (b).

By providing a transparent adhesive layer over the entire area of the substrate, the lens array can be adhered to another substrate. Alternatively, the lens array may be adhered to another substrate by placing adhesive only at selected locations, for example around each transparent. This provides a void between the transparent layer and the substrate that is free of adhesive, thus eliminating the reduction in focusing power that would occur if the refractive index of the transparent adhesive layer were close to that of the lens array. The adhesive is only provided at selected locations and in principle an opaque adhesive may be used.

Fig. 27 is a cross-sectional view (from above) of a display 64 according to another embodiment of the present invention. The display also includes an image display unit 65 and has a parallax optic 66 mounted within the image display unit. In this embodiment, the parallax optic is a prism array 66.

A prism array 66 is formed on the base substrate 19 (which may be made of glass, for example), and a planarization layer 67 is provided on the prism array. The base substrate 19, the prism array 66 and the planarization layer 67 form one substrate 68 of the image display unit 65. An image display layer 8, such as a pixel liquid crystal layer, is mounted between the substrate 68 and the second substrate 6. Other components of the image display unit, such as the color filter array (in case of full color display), the alignment layer, the conversion unit and the electrodes, are all known and are omitted in fig. 27.

The display 64 includes a backlight 69 that illuminates the image display unit 65 with collimated light or partially collimated light. Light from the backlight is refracted by the prisms of the prism array and directed towards either the left viewing window 2 or the right viewing window 3. If two alternating images are displayed on the pixels 70 of the image display layer 8, a directional display is provided. Using a prism array to direct light to both viewing windows means that backlight 69 with a relatively low degree of parallelism can be used, whereas if a lens array were used instead of a prism array, a backlight with a high degree of parallelism would have to be used.

One method for manufacturing the substrate 68 is to mount a photoresist layer on the base substrate 19. The refractive index of the photoresist should be as close as possible to the refractive index of the base substrate 19, and the refractive index of the photoresist is preferably equal or substantially equal to the refractive index of the base substrate 19. The prism array 66 is then patterned in a photoresist layer using known photolithographic masking, illumination, and etching steps.

A planarization layer 67 is then mounted on the prism array 66. The planarization layer 67 preferably has a minimum thickness required to planarize the substrate 68.

Features such as alignment layers, color filters, etc. may be provided on the substrate 68 using any suitable technique. The substrate 68 is then assembled with the second substrate 6 to form the image display unit 65.

The refractive index of planarization layer 67 must then be different from the refractive index of prism array 66 so that light is refracted at the interface of prism array 66 and planarization layer 67. The refractive index of the planarization layer may be greater or less than the refractive index of the prism array 66, although in practice it is easier to find a material with a refractive index less than that of the prism array for use in the planarization layer. (the direction of refraction depends on whether the index of refraction of the planarization layer is greater or less than the index of refraction of the prism array).

Embodiments of the invention have been described above with reference to specific parallax lenses. However, the embodiments are not limited to the particular type of parallax optic illustrated, and other types of parallax optic may be used.

The present invention allows a substrate on which a parallax lens is mounted to be used as a substrate for an image display unit such as a liquid crystal display unit. This has the advantage that in the manufacture of the display unit the alignment of the parallax optic and the display unit pixels is done. This allows the alignment to be done more accurately than in the case where the known external parallax optic aligns all of the liquid crystal display cells (as shown in figure 1). Further, eliminating the step of affixing or adhering the parallax glass to the entire image display unit makes the manufacturing process faster and cheaper.

Fig. 28 is a schematic plan cross-sectional view of a multi-view directional display 76, in accordance with another embodiment of the invention. The display 76 includes a first transparent substrate 6 and a second transparent substrate 71 with the image display layer 8 mounted between the first substrate 6 and the second substrate 71. A color filter array (not shown) is mounted on the second substrate 71, and thus the second substrate is referred to as a color filter substrate.

The first substrate 6 is provided with pixel electrodes (not shown) for defining a pixel array of the image display layer 8 and conversion elements (not shown), such as Thin Film Transistors (TFTs), for selectively addressing the pixel electrodes. The substrate 6 is referred to as a "TFT substrate". In this embodiment, the image display layer 8 is a liquid crystal layer 8. The present invention is not limited thereto and any transmissive image display layer may be used.

The display 76 is mounted such that each of the colour filters is substantially opposite a respective pixel of the image display layer 8. Other components such as alignment layers may be mounted on the surface of the

substrate

6, 71 adjacent the image display layer, and a counter electrode may also be mounted on the CF substrate 71; these components are known and will not be described further. Further, the display 76 may include other components, such as a viewing angle enhancement film, an antireflection film, etc., mounted outside the image display unit; these components are also known and will not be described further.

The color filter substrate 71 includes a transparent waveguide 74, a linear polarizer 73 mounted on the waveguide 74, and a transparent layer 72 mounted on the linear polarizer 73. The waveguide 74 forms part of the color filter substrate 71 as well as part of the backlight of the display.

In use, the backlight of the display 76 is comprised of a waveguide 74, with one or more light sources 75 mounted along the sides of the waveguide. Only one light source 75 is shown in fig. 28, mounted on one side 74a of waveguide 74, but the invention is not limited to the particular configuration of backlight shown in fig. 28, and more than one light source may be used. As an example, the display may provide two light sources mounted on

opposite sides

74a,74b of the waveguide 74. The light source 65 preferably extends along all or substantially all of the respective sides of the waveguide and may be, for example, a fluorescent tube.

The waveguide 74 is adhered to the polarizer 73 with an adhesive 81 mounted to the edge of the polarizer 73, and since the adhesive 81 is mounted only to the edge of the polarizer 73, a gap 82 exists in most of the area between the waveguide 74 and the polarizer 73. As is well known, light from the light source 75 enters the waveguide 74 and is collected in the waveguide 74 by the phenomenon of total internal reflection, i.e. light propagating within the light guide that is incident from the front or back of the waveguide 74 undergoes total internal reflection at the waveguide/air interface and does not exit the waveguide.

Alternatively, the waveguide 74 and the polarizer 73 may be adhered with a low refractive index transparent adhesive, that is, an adhesive having a refractive index lower than that of the waveguide. A low index adhesive may be installed in the entire region of the polarizer 73, and internal reflection occurs in front of the waveguide 74 due to the difference in refractive index between the adhesive and the waveguide.

According to the embodiment of fig. 28, the diffusion point is at a selected region 84 of the front face 74c of the waveguide 74. If light propagating within the waveguide is incident on region 84 of the front face 74c of the waveguide, where the diffusion point is located, the light is not specularly reflected, but rather is scattered by the diffusion point, as shown in FIG. 28. Thus, some of the light is scattered out of the waveguide towards the image display layer 8.

Light is scattered out of waveguide 74 only in areas 84 where diffuse points are present, and no light exits waveguide 74 where there are no diffuse points. The waveguide 74 thus has a region where light is emitted (corresponding to the region 84 where the diffusion point is present) and a region where light is not emitted. If the area 84 where the diffuse spots exist has a stripe shape extending into the plane of the paper of fig. 28, a portion of the area of the waveguide 74 emits light of a corresponding size, shape and location to the transmissive area of the parallax barrier, which is, for example, the parallax barrier 13 of fig. 6 (a), and another portion of the area of the waveguide 74 does not emit light of a corresponding size, shape and location to the opaque area of the parallax barrier. The parallax barrier is thus effectively defined at the front face 74c of the waveguide 74, within the thickness of the colour filter substrate 71.

Areas of the waveguide 74 where there are no diffusion points may be covered by an absorbing material to ensure that no light is scattered from these areas. This reduces the intensity of light emitted from the light guide region corresponding to the opaque region of the parallax barrier 13 of fig. 6 (a).

The diffusing dots may be composed of diffusing structures, diffractive structures or micro-refractive structures. Their exact structure is not important because light is scattered from the areas 84 where the diffusion points are provided and not scattered in areas where no diffusion points are provided.

The display 76 of fig. 28 does not require a parallax barrier slot array and therefore light emitted by the waveguide 74 is not absorbed by the opaque regions of the parallax barrier slot array. The display 76 of figure 28 provides a brighter image for a given output from the light source 75 than a display having a parallax barrier slit array, for example the display of figure 6 (a).

The polarizer 73 serves as a known polarizer for the image display layer 8. Depending on the mode of operation of the image display layer, a second linear polariser (not shown) may be provided opposite the polariser 73 of the image display layer.

The display 76 can be manufactured by the same method as that shown in fig. 26 (a) to 26 (d). In this method, an image display unit, comprising a front substrate 6, an image display layer 8 and a rear substrate, will be initially manufactured. The rear substrate is then reduced in thickness to form the transparent layer 72. Then, the polarizer 73 would be adhered to the transparent layer 72 and the waveguide 74 would be adhered to the polarizer 73.

Alternatively, the color filter substrate 71 may be manufactured by adhering a polarizer 73 to the waveguide 74. In the case of, for example, a glass transparent layer 72, the transparent layer 72 is then adhered to the polarizer 73. Alternatively, a transparent plastic layer or a transparent resin layer may be mounted on the polarizer 73 to form the transparent layer 72. The completed color filter substrate 71 is then assembled with a TFT substrate to form a display 76. In this method, the waveguide 74 forms the basic substrate of the color filter substrate 71.

Fig. 29 is a schematic plan cross-sectional view of a multi-view directional display 76' in accordance with another embodiment of the invention. The display 76' generally corresponds to the display 76 of fig. 28, and only the differences will be described.

In the display 76' of fig. 29, a polariser 73 is positioned near the rear of the waveguide 74, for example adhered to the waveguide 74 using a transparent adhesive (not shown). The refractive indices of the waveguide 74, the polarizer 73 and the adhesive are selected such that light propagating in the waveguide 74 enters the polarizer 73 with substantially no internal reflection at the interface of the waveguide 74 and the polarizer 73. Internal reflection occurs behind the polarizer 73 as shown by the ray path in figure 29.

In this embodiment, the distance between the front face 74c of the waveguide 74 and the image display layer 8 is reduced by the thickness of the polariser. Light that is internally reflected at the back of the waveguide is reflected with a polarization that is maintained as the light is scattered out of the waveguide.

Fig. 30 is a schematic plan cross-sectional view of a multi-view directional display 77 according to another embodiment of the invention. The display 77 includes a first transparent substrate 6 and a second transparent substrate 80, and the image display layer 8 is mounted between the first substrate 6 and the second substrate 80. A color filter array (not shown) is mounted on the second substrate 80, and thus the second substrate is referred to as a color filter substrate.

The first substrate 6 is provided with pixel electrodes (not shown) for defining a pixel array 8p,8s of the image display layer 8 and conversion elements (not shown), such as Thin Film Transistors (TFTs), for selectively addressing the pixel electrodes. The substrate 6 is referred to as a "TFT substrate". In this embodiment, the image display layer 8 is a liquid crystal layer 8. The present invention is not limited thereto and any transmissive image display layer may be used.

The display 77 is mounted such that each of the colour filters is substantially opposite a respective pixel of the image display layer 8. Other components such as an alignment layer may be mounted on the surface of the

substrate

6, 80 adjacent the image display layer, and a counter electrode may also be mounted on the CF substrate 80; these components are known and will not be described further. Further, the display 77 may include other components such as a polarizer, a viewing angle enhancement film, an antireflection film, and the like, which are mounted outside the image display unit; these components are also known and will not be described further.

In this embodiment, the display includes a parallax barrier 79 having a transmitting portion 79a and an opaque portion 79b. In this embodiment, the opaque transmissive portions 79a of the parallax barrier 79 are polarizing slits, transmit light of one polarization direction, and substantially block light of an orthogonal polarization direction. The pixel 8s,8p emits/transmits light of a first polarization state or a second polarization state. In FIG. 30, the two polarization states are the P-linear polarization state and the S-linear polarization state. The pixels labeled "8S" or "8P" emit/transmit S-polarized light or P-polarized light, respectively. The transmitting portion 79a of the parallax barrier 79 is also labeled "P" or "S" and indicates that P-polarized light or S-polarized light is transmitted, respectively.

The parallax barrier 79 is mounted on the base substrate 19. A transmissive separator layer 78, which may be a glass layer, a transparent resin layer or a transparent plastic layer, is mounted between the image display layer 8 and the parallax barrier 79.

The parallax barrier may be formed, for example, by a patterned polarizer, one region of which transmits P-polarized light but blocks S-polarized light, and another region of which transmits S-polarized light but blocks P-polarized light. Opaque regions 79b may be deposited on the patterned polarizer by, for example, printing. Alternatively, the parallax barrier may be formed by a combination of a uniform linear polariser and a patterned retarder having a region of polarisation plane for rotated light at 90 ° and another region of polarisation plane for non-rotated light; opaque regions 79b may be deposited on the patterned polarizer by, for example, printing.

The parallax barrier is arranged so that the slit 79a transmitting light of a particular polarization is not in front of the pixel emitting/transmitting that polarization. The slits 79a transmitting the P-polarization state are therefore not in front of the pixels 8P emitting/transmitting the P-polarization state, and the slits 79a transmitting the S-polarization state of the parallax barrier are not in front of the pixels 8S emitting/transmitting the S-polarization state. As a result, light of one polarization state emitted/transmitted by one pixel can only pass through the parallax barrier 79 in a range of first and second directions that are different and are located on opposite sides of the normal to the display surface of the display. Light emitted in a parallel or near normal direction by e.g. an S-pixel will be incident on the slit 79a, which transmits only P-polarization, or the opaque part 79b of the parallax barrier, and will thus be blocked. The intensity of light emitted in the normal direction or near the normal direction of the display of this embodiment is therefore low. The device thus provides a black window between the viewing windows of the two images, thus providing the advantages described hereinbefore with reference to fig. 11 (b)).

A black mask (represented by non-transmissive region 8 b) is provided between adjacent pixels 8s, 8p. The angular extent of the black central window can be varied by varying the black mask: the pixel ratio changes (while keeping the pixel pitch constant). The greater the width of the black mask between adjacent pixels, the greater the angular extent of the black central window.

The angular extent of the black central window is also determined by the width of the polarizing slits 79a of the parallax barrier 79. The angular extent of the black central window can be varied by varying the width of the polarizing slot (while keeping the slot spacing constant). The smaller the width of the polarizing slit of the parallax barrier, the larger the angular range of the black central window.

In any of the embodiments described above including a lens array, the lens array may be a GRIN (graded index) lens array, as described above with reference to the embodiment of fig. 20 (b).

Fig. 31 shows a modification of the backlight of the display 76 of fig. 28. The backlight of fig. 31 comprises a first waveguide 74 and one or more first light sources 75 arranged at the sides of the first waveguide. In fig. 31 two first light sources 75 are shown arranged at

opposite sides

74a,74b of the first waveguide 74, but the invention is not limited to this particular configuration and only one light source or more than two light sources may be provided. The light source 75 preferably extends to all or substantially all of the respective sides of the first waveguide and may be, for example, a fluorescent tube.

The diffusion point is at a selected region 84 of the rear face 74c of the first waveguide 74. The area 84 where the diffuse spots are present may be, for example, in the form of a strip and extends into the plane of the paper of fig. 31. If light propagating within the first waveguide enters the region 84 of the front face 74c of the waveguide that provides the diffusion point, the light is not specularly reflected, but is scattered out of the first waveguide, as explained above with reference to FIG. 28 (the viewer in FIG. 31 assumes that at the top of the page, the light is scattered out of the first waveguide in a generally upward direction).

The backlight further comprises a second waveguide 74 'and one or more second light sources 75' arranged at the side of the first waveguide. The second waveguide 74' is located and generally parallel to the first waveguide 74; the second waveguide 74' generally corresponds to the size and shape of the first waveguide 74. In fig. 31, two second light sources 75 'are shown arranged on opposite sides 74a',74b 'of the second waveguide 74', but the present invention is not limited to this particular configuration and only one light source or more than two light sources may be used. The light source 75' preferably extends to all or substantially all of the respective sides of the second waveguide and may be, for example, a fluorescent tube.

The diffusion point 89 is provided on substantially the entire front face 74d 'of the second waveguide 74'. Thus, when the second light source 75 'is illuminated, light is scattered out of most of the area of the front face 74d' of the second waveguide.

The backlight of fig. 31 is therefore switchable between a "patterned mode" and a "uniform mode". In the "patterning mode", the first light source 75 is illuminated and the second light source 75' is not illuminated. The light propagates only in the first waveguide 74 and the backlight has regions that emit light (these regions correspond to the regions 84 where the diffusion spots are present) and regions that do not emit light (these regions correspond to the regions where the diffusion spots are not present). In the "uniform mode", the second light source 75' is illuminated and light propagates in the second waveguide. Since the diffuse spot 89 is provided over substantially the entire front face 74d 'of the second waveguide 74', the backlight provides substantially equal illumination in a "uniform mode" over its entire area. The display with backlight of fig. 31 can be changed from a directional display mode to a known 2-D display mode by changing the backlight from a "graphics mode" to a "uniform mode".

In the "uniform mode," the first light source 75 may be illuminated or not illuminated. If desired, the first light source may be continuously kept on, and the backlight is "uniform mode" or "patterned mode" by switching the second light source 75' on or off, respectively. (keeping the patterned waveguide illuminated in a uniform mode can result in variations in intensity across the back-lit area, but these possible disadvantages are important in some applications where only the second light source 75' must be switched).

To ensure that internal reflection occurs at the rear face 74c of the first waveguide, the spacing between the first waveguide 74 and the second waveguide 74' must have a smaller index of refraction than the first waveguide 74. This may be readily achieved by providing a gap between the first waveguide 74 and the second waveguide 74', or alternatively the space between the first waveguide 74 and the second waveguide 74' may be filled with a light transmissive material having a low refractive index.

The rear of the region 84 providing the diffusion point on the first waveguide 74 may be made reflective, for example by being coated with a metal coating. If this is done, any light scattered into the second waveguide 74' by the diffusing dots will be reflected back to the viewer. (if made reflective behind the region 84 where the first waveguide 74 provides a point of diffusion, the first and second light sources must be illuminated to obtain a uniform mode since the reflector will block light from being scattered upwards from the second waveguide 74')

Each waveguide may have an anti-reflective coating (not shown)

FIG. 32 shows another backlight of the present invention. The backlight comprises a waveguide 74 and one or more light sources 75 arranged at the sides of the waveguide. Two light sources 75 are shown in fig. 32, arranged on

opposite sides

74a,74b of the waveguide 74, but the invention is not limited to this particular configuration and only one light source or more than two light sources may be used. The light source 75 preferably extends to all or substantially all of the respective sides of the waveguide and may be, for example, a fluorescent tube.

The waveguide 74 comprises a layer 87 of liquid crystal material sandwiched between two light transmissive substrates 92, 93. The layer of liquid crystal material is addressable, for example, by electrodes (not shown) that allow an electric field to be applied to the liquid crystal layer 87. Regions 87a,87b of the liquid crystal layer (shown in dashed lines in fig. 32) can be addressed independently of one another, for example by using appropriately patterned electrodes which allow an electric field to be applied to selected regions of the liquid crystal layer. The regions 87a,87b of liquid crystal layer may be, for example, in the form of strips and extend into the plane of the paper of fig. 32.

Regions 87a,87b of the liquid crystal layer can be switched to a scattering mode or a clear transmission mode. If all the liquid crystal regions are switched to the transmissive mode, the light propagates within the waveguide with minimal scattering-the light undergoes internal reflection at the upper surface 92a of the upper substrate 92, enters the lower substrate 93 through the upper substrate 92 and the liquid crystal layer 87, undergoes internal reflection at the lower surface 93b of the lower substrate 93, is reflected back to the upper substrate 92, etc. Little or no light is emitted from the waveguide.

To cause light to be emitted from the waveguide, one or more of the liquid crystal regions are transformed to form scattering regions, as shown at 85 in figure 32. When light propagating within the first waveguide is incident on the scattering region 85, the light is scattered out of the waveguide as explained above with reference to FIG. 28 (the viewer in FIG. 32 assumes that at the top of the page, the light is scattered out of the waveguide 74 generally in an upward direction).

Fig. 32 shows a waveguide in which each of the alternating liquid crystal regions 87A is transformed to produce scattering regions 85. The other liquid crystal region 87B is transformed so as not to be scattered. Light is emitted only from the front region of waveguide 74 corresponding to scattering region 85, with the backlight operating in "patterned mode".

If all of the liquid crystal regions 87A,87B are altered to form scattering regions, the liquid crystal layer 87 scatters light throughout it, so that light is emitted from the entire region of the waveguide 74. Thus, when all of the liquid crystal regions 87A,87B are switched to form scattering regions, the backlight operates in a "uniform mode". Thus by switching the liquid crystal regions, the backlight can be switched between a "patterned mode" and a "uniform mode". The display with backlight of fig. 32 can be changed from a directional display mode to a known 2-D display mode by changing the backlight from a "graphics mode" to a "uniform mode".

In one implementation of the backlight of fig. 32, the rear face 92b of the upper substrate 92 is flat over its entire area. This implementation requires that layer 87 comprises a liquid crystal material that can be switched between a state that transmits light without significant scattering and a state that scatters light, for example, polymer-dispersed liquid crystal (PDLC). The scattering region 85 may be obtained by shifting the liquid crystal layer region to its scattering mode.

Thus, for example, region 87A of the liquid crystal layer is switched to a scattering mode, resulting in scattering region 85; light entering the region 87A of the liquid crystal layer through the upper substrate 92 is scattered by the liquid crystal, and some of the light is reflected upward and may disappear from the front of the waveguide 74. In contrast, the region 87B of the liquid crystal layer is switched to the non-scattering mode, and light entering the region 87B of the liquid crystal layer through the upper substrate 92 passes only through the lower substrate without being scattered by the liquid crystal. When the region 87B of the liquid crystal layer is in the non-scattering mode, the backlight is in the "patterned mode".

To obtain a "homogeneous mode" for the backlight, all regions 87A,87B of the liquid crystal layer are switched to the scattering mode. The rear face of the waveguide 74 is substantially scattered over its entire area.

In this implementation, the size and location of the scattering 85 and non-scattering regions may be varied. For example, the analog parallax barrier may have a slit-to-barrier ratio of 2: 1, by switching two adjacent liquid crystal regions to a scattering mode, the next liquid crystal region to a non-scattering mode, the next two liquid crystal regions to a scattering mode, the next liquid crystal region to a non-scattering mode, and so on.

Alternatively, the areas of the rear face 92b of the upper substrate 92 corresponding to the desired locations of the scattering regions 85 may be roughened so that these areas always scatter light. By switching the liquid crystal region 87B to either the scattering mode or the non-scattering mode, the backlight can be switched between the "uniform mode" and the "patterned mode".

As another alternative, the rear face 92b of the upper substrate may be optically roughened over the entire area. This embodiment requires a layer 87 of liquid crystal material having a changeable refractive index. The scattering region 85 is obtained by transforming the corresponding liquid crystal region 87A so that the refractive index of the liquid crystal does not match the refractive index of the waveguide 74. Light propagating within the upper substrate will "see" the optically rough surface behind the upper substrate and be scattered.

The non-scattering region is obtained by transforming the corresponding liquid crystal region 87B so that the refractive index of the liquid crystal region 87B matches the refractive index of the upper substrate 92. Light propagating within the upper substrate does not "see" the optically rough surface behind the upper substrate, passes through the liquid crystal layer, and is not scattered (and subsequently internally reflected at the rear surface 93b of the lower substrate).

If the position of the scattering region is fixed, a reflector may be provided behind the scattering region 85, shown at 86 in FIG. 32. Any light scattered by the scattering region 85 towards the rear substrate 93 will be reflected by the reflector towards the viewer.

Fig. 33 shows another backlight. The backlight comprises a waveguide 74 and one or more light sources 75 arranged at the sides of the waveguide. Two light sources 75 are shown in fig. 33, arranged on

opposite sides

74a,74b of the waveguide 74, but the invention is not limited to this particular configuration and only one light source or more than two light sources may be used. The light source 75 preferably extends to all sides of the waveguide and may be, for example, a fluorescent tube.

The diffusion point is at a selected region 84 of the rear face 74c of the waveguide 74. The area 84 where the diffusion points are present may be, for example, a band shape and extends to the plane of the paper of fig. 33. If light propagating within the first waveguide is incident on the region 84 of the front face 74c of the waveguide providing the diffusion point, the light is not specularly reflected, but is scattered out of the first waveguide, as explained above with reference to FIG. 28 (the viewer in FIG. 33 assumes that at the top of the page, the light is scattered out of the first waveguide 74 generally in an upward direction).

Lens array 88 mounts the front face of waveguide 74. The lens array directs light emitted by the waveguide 74 primarily into a first direction (or first range of directions) 90 and into a second direction (or second range of directions) 91. The first direction (or first range of directions) 90 and the second direction (or second range of directions) 91 are preferably separated by a third range of directions including the normal direction. Since the light is directed mainly into the first and second directions (or first and second ranges of directions) 90, 91, the intensity of the light in the first and second directions (or first and second ranges of directions) 90, 91 is greater than the intensity of the light in the third range of directions. The first direction (or first range of directions) 90 and the second direction (or second range of directions) 91 are located on opposite sides of the normal direction, preferably substantially symmetrical about the normal.

The backlight of fig. 33 is particularly suitable for use with directional displays. For example, a typical dual view display displays two images, the images being displayed in directions on opposite sides of the normal direction. The backlight of fig. 33 directs light primarily into the direction in which the two images are displayed by the dual view display, thus producing a bright image. Conversely, backlight is known to have maximum intensity in the normal direction and less intensity when viewed from the off-axis direction.

A 4-view illumination system can be produced by using a 2-D microlens array and a 2-D diffusing spot array. This would provide four views, with two views arranged on top of each other, thus providing horizontal and vertical separation of the views.

Fig. 34 shows another backlight. This backlight is the same as the backlight of fig. 33 in that it has an array of lenses for directing the emitted light into two preferred directions (or ranges of directions) 90, 91. The backlight of fig. 34 further comprises a second waveguide 74' and a second light source 75' arranged on each side of the second waveguide 74'. The diffusion point 89 is in front of the second waveguide 74'. The second waveguide 74 'of fig. 34 corresponds generally to the second waveguide 74' of fig. 31. The backlight of fig. 34 can be switched between a "patterned mode" and a "uniform mode" in the manner described above for the backlight of fig. 31.

The backlight of fig. 31-34 may be incorporated into, for example, the display 76 of fig. 28 or the display 76' of fig. 29.

In the embodiment of fig. 31 to 34, the density of the diffusing spots can be adjusted to vary the spatial illumination uniformity, compensating for the decrease in intensity of light propagating within the waveguide due to the increased distance from the light source 75. This can be applied to both waveguides in the embodiment of fig. 31 and 34.

In the embodiments of fig. 31 to 34, the diffusing dots may be replaced by micro-reflective structures such as prisms, protrusions (protrusions), and the like. This can be used, for example, to control the emission directionality of the light guide area having the diffusion points.

In the above-described embodiments, the parallax optic has been mounted on the same substrate as the color filter. Alternatively, a parallax optic may be mounted on the TFT substrate 6 of the display, and for each of the embodiments described above in which the parallax optic is mounted on the color filter substrate, there is a corresponding embodiment in which the parallax optic is mounted on the TFT substrate. In the modified embodiment described above, the array of conversion units such as the array of TFTs and the parallax mirror unit are to be mounted on the base substrate of the TFT substrate, and the separation layer may be interposed between the parallax mirror and the thin film transistor. The interval between the parallax barrier and the image display layer is the thickness of the separation layer (assuming that the separation layer is mounted on the parallax lens). Also, in the embodiment of fig. 22 to 25, the prism 53 may be mounted to the TFT substrate.

Further, in some liquid crystal panels, color filters are mounted on the same substrate as thin film transistors. The present invention can be applied to the above-described apparatus. For example, light transmissive spacers (e.g., resin, glass or plastic spacers) may be mounted on the TFTs (or other conversion cells) and the color filters, and parallax mirrors may be mounted on the spacers.

Embodiments of the present invention, in addition to the embodiments shown in fig. 22-25, 28-34, may be used as a rear bulkhead apparatus (as shown in fig. 4) or as a front bulkhead apparatus (as shown in fig. 1).

When the device of the present invention in which the parallax barrier is a parallax barrier is used in the rear barrier mode of fig. 4, it is preferable if the parallax barrier unit is reflective on the side of the backlight. Light from the backlight incident on the opaque regions of the barrier will be reflected and may be re-reflected from the backlight so that it may pass through the parallax barrier and the display device. This will increase the brightness of the display. The surface of the parallax barrier unit remote from the backlight is preferably absorbing to prevent interference.

The invention has been described above with reference to an image display unit comprising a liquid crystal layer. However, the present invention is not limited to this particular image display unit, and any suitable image display unit may be used. As an example, an OLED (organic light emitting device) image display unit may be used.

Claims

1. A method of manufacturing a display device, comprising the steps of:

(a) Reducing the thickness of a first substrate (60) of an image display unit, the image display unit including the first substrate (60), a second substrate (61), and an image display layer (8) mounted between the first substrate and the second substrate;

(b) A third substrate (62) is adhered to the first substrate with a parallax optic (13) mounted between the third substrate and the first substrate.

2. The method according to claim 1, wherein the parallax optic (13) is defined on or within a first major surface of a third substrate (62), and step (b) comprises adhering the first major surface of the third substrate to the first substrate of the image display unit.

3. A display device, comprising:

an image display unit including a first substrate (60), a second substrate (61), and an image display layer (8) mounted between the first substrate and the second substrate; and

a third substrate (62) adhered to the first substrate, the parallax optic (13) being mounted between the third substrate and the first substrate.

4. A display device according to claim 3, wherein the parallax optic (13) is defined on or in a first major surface of a third substrate (62), and the first major surface of the third substrate is adhered to the first substrate of the image display unit.