WO2014033699A2

WO2014033699A2 - Stereoscopic displays and methods

Info

Publication number: WO2014033699A2
Application number: PCT/IB2013/059960
Authority: WO
Inventors: Dac BUI
Original assignee: Bui Dac
Priority date: 2013-07-10
Filing date: 2013-11-07
Publication date: 2014-03-06
Also published as: WO2014033699A3

Abstract

In one preferred form of the present invention, there is provided a lens arrangement 10 for an autostereoscopic display 12. The lens arrangement 10 comprises a series 14 of facet type portions 16 for receiving light 18 from a series 20 of pixel groups 22. The facet type portions 16 are arranged in the series 14 to assist with directing the light 18 from the pixel groups 22 to a number of viewing positions 24.

Description

S TE RE O S C OPIC D IS PLAYS AND ME THOD S

FIE LD O F THE INVENTION

The present invention relates to stereoscopic displays and methods.

BACKGROUND T O THE INVENTION

Current 3D display technologies can be considered as being divided into two groups, comprising: those with glasses and those without glasses. Each of these groups have particular advantages and disadvantages.

Glasses type display technologies generally use polarized light or shutter technology. The main advantage of this type of display is that 3D images can be seen at any position in front of the display. As such there is provided a continuous multitude of viewing positions.

On the other hand, the main disadvantages are related to the glasses. Glasses are typically expensive, inconvenient and need to be handled with care. The wearers may experience headache and dizziness upon prolonged usage. The glasses may be misplaced and be hard to find. When a viewer does not have glasses, the viewer will not just see plain 2D images, rather the images themselves will blurry due to the simultaneous perception of both left and right images by each eye. Another less well known drawback associated with the use of glasses type display technologies is their inability to generate multi-perspective 3D images or parallax which is an important component in human depth perception.

Glasses free type display technologies sometimes use a parallax barrier or lenticular lens technology. The main advantage of this type of display technology is the absence of the need for a pair of glasses. The main disadvantage of this type of display technology is the limited number of viewing zones. Furthermore the viewing quality of the viewing zones generally drops off significantly as one moves away from the central position. There is also sometimes a narrow range of the viewing distance from the display. In other words viewers outside this range are either too close or too far away and will not be able to observe the 3D effect. This can be considered as there being only one general viewing zone that contains the viewing positions. Whilst a background to the invention has been provided, it is to be recognised that any discussion in the present specification is intended to explain the context of the present invention. It is not to be taken as an admission that the material discussed formed part of the prior art base or relevant general knowledge in any particular country or region.

SUMMARY OF THE INVENTION

According to a first aspect of preferred embodiments herein described there is provided a lens arrangement for an autostereoscopic display comprising: a series of facet type portions for receiving light from a series of pixel groups; the facet type portions being arranged in the series to assist with directing the light from the pixel groups to a number of viewing positions.

Preferably the lens arrangement as a claimed in claim 1 wherein the facet type portions face towards the pixel groups and at least some of the facet type portions are inset by extending inwardly to provide the lens arrangement with a reduced thickness.

Preferably there are provided pairs of facet portions, each facet type portion of a pair of the facet type portions being offset by a predetermined distance and being of different angularity to encourage convergence of the associated light beams in a viewing zone.

Preferably the facet type portions are provided in the series +/- (-5, -3, -1, +2,+4 ,+6), wherein: (i) the positive integer 1 represents a base angularity facet type portion; (ii) higher integers represent higher angularity facet type portions; and (iii) negative integers represent a mirrored angularity of the facet type portion associated with the positive version of the integer.

Preferably the facet type portions are provided in the series +/- (2x-l for x=-N to 0; followed by 2x for x=l to N+l) wherein: (i) the positive integer 1 represents a base angularity facet type portion; (ii) higher integers represent higher angularity facet type portions; and (iii) negative integers represent a mirrored angularity of the facet type portion associated with the positive version of the integer. Preferably the facet type portions are provided in the series +/- (2x-l for x=-N to 0; followed by 2x for x=l to N+l ; followed by 2x-2 for x=-N to 0; followed by 2x-l for x=l to N+l) wherein: (i) the positive integer 1 represents a base angularity facet type portion; (ii) higher integers represent higher angularity facet type portions; and (iii) negative integers represent a mirrored angularity of the facet type portion associated with the positive version of the integer.

Preferably a concave surface is divided into portions wherein the portions are represented as x for x=-M to - 1 followed by x for x= 1 to M from one end to the other provides the basis of the curvature of the facet type portions; the facet type portions being provided in the series +/- (2x-l for x=-N to 0; followed by 2x for x=l to N+l ; followed by 2x-2 for x=-N to 0; followed by 2x-l for x=l to N+l) wherein: (i) the positive integer 1 represents a base angularity facet type portion; (ii) higher integers represent higher angularity facet type portions; and (iii) negative integers represent a mirrored angularity of the facet type portion associated with the positive version of the integer.

Preferably along the series of the facet type portions, the facet type portions are arranged to skip an angularity range that is later provided a predetermined distance away from the position at which the angularity range is skipped.

Preferably the facet type portions are arranged in a series of pairs of lens arrangement portions; the lens arrangement portions being spaced apart.

Preferably the pixel groups are arranged in a series of pairs and each pair of lens arrangement portions accommodates one or more of the pairs of pixel groups.

Preferably in each pair of pixel groups a first pixel group provides for a first field of view and the other pixel group, in the pair, is provided for providing a second field of view.

Preferably in each pair of pixel groups, the pixel groups, are arranged one after the other to form a length and the pair of lens arrangement portions accommodating the pair spans the length. Preferably the number of facet type portions is the same in each lens arrangement portion and provides the basis for the number of viewing positions, the viewing positions being provided in a viewing zone.

Preferably each lens arrangement portion of a pair of lens arrangement portions is asymmetrical and comprises a mirror image of the other lens arrangement portion in the associated mid-plane.

Preferably the pixel groups are arranged in a series of pairs and the arrangement includes an angulating portion for directing light from each pixel group in a pair of the pixel groups to respective left and right visual fields.

Preferably the angulating portion includes at least one facet type angulating portion spanning the width of each pixel group pair.

Preferably the facet type angulating portions form a v-shaped channel, the pixel group pairs being arranged side by side to face opposite sides of the v-shaped channel.

Preferably the angulating portion includes an inner portion and an outer portion, the inner portion for directing light from each pixel group in a pixel group pair to respective left and right visual fields; and the outer portion for providing a viewing zone correction portion for directing light originating from the pixel group pairs towards a viewing zone, the viewing zone correction portion having a number of facet type correction portions that are inset to provide a reduced thickness of the viewing zone correction portion.

Preferably the lens arrangement includes a viewing zone correction portion for directing light from pairs of the pixel groups, towards a viewing zone, the viewing zone correction portion having a number of facet type correction portions that are inset to provide a reduced thickness of the viewing zone correction portion.

Preferably each facet type portion is associated with a different viewing position within a viewing zone.

Preferably the pixel groups are arranged into a series of pixel group pairs; the pixel group pairs being arranged into rows and columns; each pixel group of a pixel group pair being in a row next to the other pixel group of the pixel group pair. Preferably the lens arrangement includes an outer viewing position correction for narrowing the viewing positions; the outer viewing position correction serving to narrow a concavity of the facet type portions.

Preferably the outer viewing position correction increases the further each pixel group is located from the centre of the row in which the pixel group is located.

Preferably the outer viewing position correction comprises a diverging gradient index portion having a refractive index that increases towards the ends of the rows of the pixel group pairs from the centre of the rows.

Preferably the lens arrangement includes a chromatic aberration adjustment that correlates with a local concavity provided by each of the facet type portions to at least partly counteract chromatic aberration effects provided by the facet type portions;

Preferably the pixel groups are arranged into a series of pixel group pairs; the pixel group pairs being spaced apart into rows and columns; each pixel group of a pixel group pair being in a row next to the other pixel group of the pixel group pair; the lens arrangement including a chromatic aberration adjustment that correlates with a local concavity provided by each of the facet type portions to at least partly counteract chromatic aberration effects provided by the facet type portions; the chromatic aberration adjustment spanning the column of each facet type portion.

Preferably the pixel groups are arranged into a series of pixel group pairs; the pixel group pairs being spaced apart into rows and columns; each pixel group of a pixel group pair being in a row next to the other pixel group of the pixel group pair; each pixel group including a pixel having a number of colour sub-pixels; the colour sub- pixels being spaced apart along an associated one of the columns.

Preferably the lens arrangement includes a chromatic aberration adjustment portion that correlates with a local concavity provided by each of the facet type portions to at least partly counteract chromatic aberration effects provided by the facet type portions; the chromatic aberration spanning the column of each facet type portion.

According to a second aspect of preferred embodiments herein described there is provided a lens arrangement for an autostereoscopic display comprising: a series of facet type portions for receiving light from a series of pixel groups arranged in pixel group pairs; the facet type portions being arranged in series to assist with directing light from the pixel group pairs to number of viewing positions.

Preferably the facet type portions are angled to adopt a nonstandard concavity or convexity that is able to provide: (i) an angulating function for directing light from each pixel group in a pixel group pair to respective left and right visual fields; (ii) a viewing zone function for directing light from each pixel group to a viewing zone; and (iii) an aberration function for limiting chromatic aberration effects of colour sub pixels of the pixel groups.

Preferably the lens arrangement has a flat outwardly facing surface and inwardly facing surface providing the facet type portions.

According to a third aspect of preferred embodiments herein described there is provided a lens arrangement for an autostereoscopic display comprising: light directing portions for receiving light from a series of pixel groups; the light directing portions comprising a series of slit type providing portions able to generate diffraction patterns from the light received from the pixel groups, the diffraction patterns having alternatively placed maxima and minima.

Preferably the slit type providing portions are arranged to correlate maxima from the pixel groups towards the same point in space.

Preferably the number slit type portions associated with a pixel group provides the basis for the number of viewing positions in a viewing zone.

Preferably the slit type portions are provided by series of pairs of slit type area for providing respective fields of view.

Preferably maxima provided by slit type areas are associated with a different viewing positions within a viewing zone.

Preferably the angulating portion includes at least one facet type angulating portion spanning the width of each pixel group pair. Preferably the angulating facet type portions form a v-shaped channel, the pixel group pairs being arranged side by side to face opposite sides of the v-shaped channel.

Preferably the angulating portion includes an inner portion and an outer portion, the inner portion for directing light from each pixel group in a pixel group pair to respective left and right visual fields; and an outer portion for providing viewing zone correction portion for directing light originating from the pixel group pairs towards a viewing zone

Preferably the viewing zone correction portion has a number of facet type correction portions that are inset to provide a reduced thickness of the viewing zone correction portion.

Preferably the pixel groups are arranged into a series of pixel group pairs; the pixel group pairs being spaced apart into rows and columns; each pixel group of a pixel group pair being in a row next to the other pixel group of the pixel group pair.

Preferably including an outer viewing position correction that increases the further each pixel group is located from the centre of the row in which the pixel group is located.

Preferably the slit type providing portions provide slit type areas and the outer viewing position correction comprises a widening of a number of slit type areas and an increasing the distance between the slit type areas the further towards the ends of the rows of the pixel group pairs from the centre of the rows.

Preferably the series of pixel groups are arranged into a series of pixel group pairs; the pixel group pairs being spaced apart into rows and columns; each pixel group of a pixel group pair being in a row next to the other pixel group of the pixel group pair; each pixel group including a pixel having a number of colour sub-pixels; the colour sub- pixels being spaced apart along an associated one of the columns.

Preferably the slit type providing portions provide slit type areas the arrangement includes a chromatic aberration adjustment provided by slit type areas having different associated widths and spacings to align the maxima from differently coloured sub pixels. Preferably the series of pixel groups are arranged into a series of pixel group pairs; the pixel group pairs being spaced apart into rows and columns; each pixel group of a pixel group pair being in a row next to the other pixel group of the pixel group pair; each pixel group including a pixel having a number of colour sub-pixels; each sub pixel being provided in a row having chromatic aberration diffraction correction in the form of a predetermined slit with and spacing based on the colour of the sub pixel.

Preferably the slit type portions providing portions and slit type portions are provided by a transmissive diffractive grating.

Preferably the slit type portions providing portions provide slit type areas having a number of concave grooves.

Preferably the slit type portions providing areas and slit type portions are provided by a slit type diffractive grating.

Preferably the slit type portions providing portions provide slit type areas having a number of elongate slits.

According to a fourth aspect of preferred embodiments herein described there is provided a lens arrangement for an autostereoscopic display comprising: a number of light directing portions for receiving light from a series of pixel groups, each pixel group containing at least four pixels, the number of pixels being herein represented as N where N>=4, each pixel of a pixel group for use in forming a different view as part of the display, the pixel groups being able to provide N different views at any one time.

Preferably the light directing portions are able to direct light to an equal number of N sub-positions.

Preferably N positions are separated by a pupillary distance or an average pupillary distance to provide N-l viewing positions.

Preferably the light directing portions comprise facet type portions that are each associated with a pixel of a pixel group on a one to one basis for directing light from the pixel group to the N sub-positions

According to a fifth aspect of preferred embodiments herein described there is provided a lens arrangement for an autostereoscopic display comprising: a number of light directing portions arranged in series for receiving light from a series of pixel groups, each pixel group containing at least five pixels, the number of pixels being herein represented as N where N>=5, each pixel of a pixel group for use in forming a different view as part of the display, the pixel groups being able to provide N different views at any one time.

Preferably each pixel is associated with at least one light directing portion and each light directing portion is associated with a single pixel.

Preferably the pixels in each pixel group are arranged in series; the first and last pixel in each series being associated with a single light directing portion and the other pixels being associated with two light directing portions.

Preferably the light directing portions are able to direct light to N-l viewing positions; each viewing position being associated with a pair of sub-positions to which light is directed by the light directing portions; the pair of sub-positions being separated by a pupillary type distance or an average pupillary distance.

Preferably each viewing position M is associated with a view M and a subsequent view M+l for M=l to N-l to provide autostereoscopy for a moving observer.

Preferably the light directing portions each comprise a facet type portion.

According to a sixth aspect of preferred embodiments herein described there is provided a method of providing a number of viewing positions for a autostereoscopic image, the method comprising: projecting light from N sets of pixels, each set of pixels providing a different view of the stereoscopic image; and directing the light to 2(N-1) sub-positions to provide N-l viewing positions wherein each viewing position M is associated with a view M and a subsequent view M+l for M=l to N-l to provide autostereoscopy for a moving observer.

According to a seventh aspect of preferred embodiments herein described there is provided a lens arrangement for an autostereoscopic display comprising a series of viewing zone correction portions able to provide a number of views to different viewing zones associated with different viewing groups, the views being formed by directing light from a series of pixel groups. Preferably the series of pixel groups are arranged into one or more rows and the viewing zone correction portions each comprise a series of viewing zone lenses associated with a row of the series of pixel groups.

Preferably the thickness of each series of viewing zone lenses comprises the thickness the corresponding row and each viewing zone lens of the series of viewing zone lenses is associated with a different viewing zone.

Preferably each viewing zone lens of each series of viewing zone lenses is associated with a viewing zone having a different viewing height.

Preferably the series of viewing zone lens comprise series of viewing zone refractive type lenses.

Preferably the each viewing zone refractive type lens of the series of viewing zone lenses is associated with a viewing zone and is angled on its forward surface to direct the light to a viewing height associated with the viewing zone.

Preferably each viewing zone refractive type lens includes a number of facet type portions on its outward surface, facing the viewing zone, that are inset to provide a reduced thickness.

Preferably each viewing zone refractive type lens includes a number of facet type portions on its inward surface, facing the pixel groups, the facet type portions being able to direct light from the series of pixel groups with increased widening from a top back viewing zone to a bottom front viewing zone.

Preferably the lens arrangement provides an autostereoscopic display for a cinema.

Preferably each viewing zone refractive type lens has a refractive index gradient.

Preferably the series of viewing zone lens comprise series of diffraction grating lenses having different spacing's and thicknesses.

According to an eighth aspect of preferred embodiments herein described there is provided a lens arrangement for an autostereoscopic display comprising: facet type portions that are inset to provide a reduced thickness, the facet type portions being arranged in series for forming stereoscopic images from a series of pixel group pairs wherein the facet type portions are angled to adopt a nonstandard concavity or convexity that is able to provide: (i) an angulating function for directing light from each pixel group in a pixel group pair to respective left and right visual fields; (ii) a viewing zone function for directing light from each pixel group to a number of different viewing zones each associated with different heights; and (iii) an aberration function for limiting colour aberration effects of colour sub pixels of the pixel groups.

Preferably the width of each facet type portion is less than 100 microns.

Preferably the width of each facet type portion between 20 and 80 microns.

Preferably the width of each facet type portion is about 50 microns.

It is to be recognised that other aspects, preferred forms and advantages of the present invention will be apparent from the present specification including the detailed description, drawings and claims.

BRIE F DE S CRIPTION O F D RAWINGS

In order to facilitate a better understanding of the present invention, several preferred embodiments will now be described with reference to Figure 1 to 66. DETAILED DE S CRIPTION OF THE E MB ODIMENT S

It is to be appreciated that each of the embodiments is specifically described and that the present invention is not to be construed as being limited to any specific feature or element of any one of the embodiments. Neither is the present invention to be construed as being limited to any feature of a number of the embodiments or variations described in relation to the embodiments.

Referring to Figure 1 there is shown a parallax barrier autostereoscopic display ('the parallax system'). As shown the parallax barrier system provides a viewing shield for the left and right eye of a person.

Referring Figure 2 there is shown a lenticular autostereoscopic display ('the lenticular system'). As shown the lenticular system comprises a directional element in the form of a lenticular lens. The lenticular lens includes a number of cylindrical segments that project from a base. Referring to Figure 3 there is shown a lens arrangement 10 according to a first preferred embodiment of the present invention. The lens arrangement 10 forms an autostereoscopic display 12. The lens arrangement 10 advantageously comprises a series _.14 of facet type portions 16. The facet type portion 16 are provided for receiving light 18 from a series 20 of pixel groups 22. The facet type portions _.16 are arranged in the series 1_.4 to assist with directing the light 18 from the pixel groups 22 to a number of viewing positions 24.

In the embodiment the facet type portions 1_.6 are provided as smooth concave (outwardly) portions facing towards the pixel groups 2_.2. The facet type portions 1_.6 are inset by extending inwardly to provide the lens arrangement .10 with a reduced thickness. The facet type portions 1_.6 are provided as surfaces _.1_.6 of a refractive lens 2_.6. The facet type portions .16 are inset by extending into the refractive lens 26.

Fresnel lenses provide a relatively compact form of lens having by providing inset facet portions. Figure 4 illustrates a concave Fresnel lens 28. The lens 28 has a series 30 of facet portions 32 each having a different angularity. Angularities can be defined and measured in a number of ways. In this embodiment an angularity is defined as being the average angle over each curved facet 32. In order to provide a numerical representation it is possible to assign integers to angularity where positive steps are taken from an axis 3_.4.

Referring to Figure 5 using the base angularity of 1 , it is possible to assign integers 2 to 6 to the right and -1 to 6 to the left. In this sense: (i) the positive integer 1 represents a base angularity facet type portion 32 ; (ii) higher integers represent higher angularity facet type portions 3_.2; and (iii) negative integers represent a mirrored angularity of the facet type portion associated with the positive version of the integer.

As shown in Figure 6 the lens arrangement 10 advantageous provides a first series 36 of the facet type portions 1_.6 as in the form '+ (-5, -3, -1 , +2,+4 ,+6)' and a second series 3_.8 of the form '- (-5, -3, -1 , +2,+4 ,+6)'.

As shown the first series 36 and the second series 38 are arranged so that the portion 40 (6) follows the portion 42 (-6). Notably, in this embodiment, a separation portion 44 spaces the portion 40 and the portion 42. The separation portion 44 is provided due to the physical separation between the pixel groups 22 during manufacture. In other embodiments the separation portion 44 could of course not be present.

If one represents the ordering of the first series 36 in a table, it is possible to apply an algorithmic formulation as follows

In other words the first series 36 comprises (2x-l for x=-N to 0; followed by 2x for

N+1) wherein: (i) the positive integer 1 represents a base angularity facet type portion; (ii) higher integers represent higher angularity facet type portions; and (iii) negative integers represent a mirrored angularity of the facet type portion associated with the positive version of the integer.

If one represents the second series 38 in a table, it is possible to apply an algorithmic formulation as follows

In this manner the form of the lens arrangement 10 can be expressed as the series shown in Figure 7, namely: 2x-l for x=-N to 0; followed by 2x for x=l to N+1 ; followed by 2x-2 for x=-N to 0; followed by 2x-l for x=l to N+1 wherein: (i) the positive integer 1 represents a base angularity facet type portion; (ii) higher integers represent higher angularity facet type portions; and (iii) negative integers represent a mirrored angularity of the facet type portion associated with the positive version of the integer.

Referring to Figure 8, along each of the first series 36 and the second series 38, the facet type portions 1_.6 are arranged to skip an angularity range that is later provided a predetermined distance 46 away from the position at which the angularity range is skipped.

Referring to Figure 9, each of the facets 16 form a pair 48 when the each facet type portion .16 of a pair 48 is offset by the predetermined distance 46 and is of different angularity to encourage convergence of the associated light beams in a viewing zone.

This is more illustrated in Figure 10 which shows a pair 50 of facet portions 16 converging in a viewing zone 5_.2. In each pair the beams converge to narrow the offset provided by the spacing distance 46.

Another lens arrangement is shown in Figures 11 and 12, namely: 2x-2 for x=-N to 0; followed by 2x-l for x=l to N+l ; followed by 2x-l for x=-N to 0; followed by 2x for x=l to N+l .

In this regard at a close range between a few millimetres to a few centimetres in front of the pixels, the locations of the beams are related to their directions or the angularity of the facet type portions as well as the positions of the light source or the pixels.

At the viewing zone, the distance is a few metres away and the locations of the beams are determined primarily by the directions of the beams or the angularity of the facet type portions and not by the positions of the facet type portions within each lens. As such, if one was to place one pixel behind each facet type portion, one could theoretically place the 12 facet type portions in a complete random order within the lens and the beams would still arrive at the viewing zone in the correct order.

By having two groups of facets, one can reduce the number of pixels down from 12 to one for left image and one for right. Arranging the facet type portions in specific orders also allows ready identification of any defective facet type portion which causes the corresponding beams to land in the incorrect spots within the viewing zone and makes the job of repairing a master stamp used to print the facet surface simpler. The arrangement of Figures 9 may be provided in some embodiments. The arrangement of Figures 9 has a slightly longer viewing distance from the display because light beams will need to travel further in order for the beams to line up in the correct order. With the first arrangement shown in Figure 9, from the perspective of the observer, the right pixel will project to the left visual field and the left pixel to the right visual field. Notably for the arrangement of Figures 1 1 and 12, the left pixel will project to the left visual field and the right pixel to the right visual field. This is of course relative.

Figure 13 illustrates a method 54 of forming the lens arrangement 10. A concave lens 56 having a smooth and continuous concave surface 58 is divided into portions .60. The portions 60 are represented as x for x=-M to -1 followed by x for x=l to M from one end to the other.

This curvature provides the basis of the curvature of the facet type portions 16. In the method 54, the portions 60 are rearranged at block 62 in a manner in which the facet type portions 16 are provided in the series + (-5, -3, -1, +2,+4 ,+6) and - (-5, -3, -1, +2,+4 ,+6) wherein: (i) the positive integer 1 represents a base angularity facet type portion; (ii) higher integers represent higher angularity facet type portions; and (iii) negative integers represent a mirrored angularity of the facet type portion associated with the positive version of the integer. The series + (-5, -3, -1 , +2,+4 ,+6) and the series - (-5, -3, -1 , +2,+4 ,+6) are complementary as indicated by the '+' and

Referring to Figure 14, there is shown a lens arrangement 64 according to a further preferred embodiment of the present invention. The lens arrangement 64 includes a series 66 of facet type portions 68 for receiving light from a series of pixel groups 70. The facet type portions 68 are arranged in the series 66 to assist with directing the light from the pixel groups 70 to a number of viewing positions 72.

The facet type portions 68 are arranged in a series 74 of pairs 76 of lens arrangement portions 78. Each lens arrangement portion 78 in a pair 76 of lens arrangement portions 78 is complementary to the other in the sense that they accommodate pixel groups 70 each for a different eye of the viewer at each viewing position 72.

As shown the pixel groups 22 are arranged in a series 80 of pairs 82. Each pair 76 of lens arrangement portions 78 accommodates a left pixel group (L) and a right pixel groups (R). Thus in each pair of pixel groups 82 a first pixel group (R) provides for a right field of view and the other pixel group, in the pair, provides a left field of view.

In each pair 82 of the pixel groups 7JL the pixel groups (L,R) are arranged one after the other to form a length and the pair of lens arrangement portions 76 accommodating the pair 82 spans the length.

Figure 15 illustrates a single lens arrangement portions 78 and a pixel group 70. The number of facet portions 68 defines the number of viewing positions 72. In the case of Figure 15 there are accordingly 6 viewing positions.

Furthermore, if one considers a pair 76 of the lens arrangement portions there are still six viewing positions. The pair simply accommodates two eyes. In this embodiment the number of facet type portions 68 is the same in each lens arrangement portion 78 and provides the basis for the number of viewing positions, the viewing positions 72 being provided in a viewing zone. Furthermore, as would be apparent, each lens arrangement portion 78 of a pair of lens arrangement portions 76 is asymmetrical and comprises a mirror image of the other lens arrangement portion in the associated mid-plane.

Figure 16 illustrates an adjustment angulating portion 84 of the lens arrangement 10 for directing light from each pixel group 70 in a pair of the pixel groups 82 to respective left and right visual fields. The angulating portion effectively shifts light by an average pupillary distance in the viewing zone 52. In the arrangement shown in Figure 16 the angulating portion 84 includes two facet type angulating portions 86 , the two angulating portions 86 each spanning the width of a corresponding pixel group 70.

The two facet type angulating portions 86 accommodate the facet type portion 68. Notably the two groups of facet type portions 68 use the same ordering sequence or the same series algorithm. This serves to simplify the manufacturing process of the facet type portions 68. The two facet type angulating portions 86 are angled oppositely as shown.

Notably, embodiments having facet type portion groups using two complimentary series will not need two opposing facet type angulating portions 86.

As shown in Figure 16, the facet type angulating portions 86 of the embodiment form a v- shaped channel 88. The pixel group pairs 70 are arranged side by side to face opposite sides of the v-shaped channel 88. Figure 17 illustrates the angulating portion 84 in more detail. As shown the angulating portion includes an inner portion 90 and an outer portion 92. The inner portion 90 serves to direct light from each pixel group 70 in a pixel group pair 82 to respective left and right visual fields. The outer portion 92 for providing a viewing zone correction portion 94 for directing light originating from the pixel group pairs towards the viewing zone 52.

Figure 18a illustrates how the lens arrangement 10 would operate without the viewing zone correction portion 94. The viewing zone correction portion is provides and convex surface 96 (outwardly) on the outer portion 92. The surface 96 refracts the light 18 to viewing positions 72 (See Figure 19). As part of the convex surface 96 the viewing zone correction portion 94 including an outer zone viewing position correction 95.

More particularly without a focusing mechanism of the convex surface 96, beams from identical sequence series of facet type portions would not correlate and would provide the beam formation shown in Figure 18a. With the viewing zone correction portion 94 (but without the outer viewing position correction 95), the beams will partially correlate as shown in Fig. 18b.

Notably the beams are prevented from full correlation by a complex aberration phenomenon which termed herein as the "viewing zone aberration". This aberration has two components: a spatial aberration and a refractive angle aberration. Spatial aberration has been mentioned briefly in a few papers known to the applicant but generally is considered not to attract much attention. Spatial aberration is primarily a monochromatic aberration and it is neither a spherical nor a field curvature aberration. The phenomenon is depicted in Figure 18c.

Spatial aberration describes the asymmetrical distortion of an image caused by unequal distances traversed by the beams to reach their targets when the beams are rotated inwards by the viewing zone correction portion. Outer beams of the outer zone pixel travel only a short distance before they meet the correspondent long inner beams from the outer zone pixels of the opposite side. The proportion of image containing long beams will be perceived by the observer to be magnified relative to the central beam while the proportion of the image with the short beams will be seen minimised. The spatial aberration of the left outer zone will be mirrored or opposite to the spatial aberration of the right outer zone resulting in a mismatch between the beams from the two outer zones.

Figure 18b demonstrates the interaction between beams with the viewing zone correction portion 94 but without the outer viewing position correction 95 with there being identical series 66 for all facet type portion 68 (i.e no complimentary series). This would be achieved with a standard focussing convex lens. Figure 18b shows partial beam correlation with evidence of spatial aberration. Notably beams from each pixel diverge equally with the same viewing angle for each pixel.

Refractive angle aberration has not been discussed previously in the context of 3D displays, to the best of the applicant's knowledge. Refractive angle aberration is a monochromatic aberration. It describes a non-linear rise in the divergence of light beams in relation to an increase in the refractive incidence angle as illustrated in Figure 18d. As shown the divergence of light beam increases with the rise in the refractive incidence angle.

Similarly to the regular chromatic aberration, both phenomena are related to the incidence angles, the wavelengths of light and the refractive index of the substance; but unlike the regular chromatic aberration which describes a polychromatic phenomenon, the refractive angle aberration describes a monochromatic phenomenon. For this reason, beams from the outer zone pixels will be wider than beams from the central zone.

The outer viewing position correction 95 comprises an adjustment designed to counteract both the spatial aberration and the refractive angle aberration. Figure 19 illustrates how the lens arrangement 10 operate with both viewing zone correction portion 94 including the outer viewing position correction 95.

The outer viewing position correction 95 serves to narrow the beam spreads from the outer zone pixels while leaving the central beams unaffected. The unequal beam divergence or unequal viewing angles of the pixels help to correlate the beams from all pixels with identical sequence series for facet type portions. In Figure 19, beam divergence from both outer zones is reduced by 20% compared to central zone. Figure 20 further illustrates the angulating portion 84. As shown there are provided a number of facet type correction portions 98 that are inset into the body of the viewing zone correction portion 94. This serves to reduce the thickness of the viewing zone correction portion 94. The angulating function is provided by the stereoscopic surface 100.

Figure 21 illustrates the pixel group pairs 76_being arranged in rows 1_.02 and columns 1_.04 in the pixel groups 82. As shown each pixel group 70 of a pixel group pair 82 is in a row next to the other pixel group 7_.0 of the pixel group pair 82. Each pixel group 7_.0 includes a single pixel _.1_.06 having three primary colour sub pixels _.108.

Due to the forming the length of the rows lens arrangement 10 includes an outer viewing position correction 1 10 illustrated in Figure 22.

In one embodiment illustrated in Figure 23, an outer viewing position correction 112 comprises a narrowing of the concavity of the facet type portions 68 increasing the further each pixel group 70 is located from the centre of the row 1.02 in which the pixel group 70 is located.

In another embodiment illustrated in Figure 24 an outer viewing position correction .1.1.4 comprises a diverging gradient index portion 116 having a refractive index that increases towards the ends of the rows of the pixel group pairs from the centre of the rows. Notably the diverging gradient index portion 1 16 includes a chromatic aberration adjustment 118 in the form a convex outwardly portion 120. The chromatic aberration adjustment 118 repeats in series to correlate with a local concavity provided by each of the facet type portions 68 to at least partly counteract chromatic aberration effects provided by the facet type portions .68,

In another embodiment illustrated in Figure 25 a chromatic aberration adjustment 122 itself increases in convexity to provide an outer viewing position correction 124. Referring to Figure 26 each pixel group 70 includes a pixel _.106 having a number of primary colour sub-pixels .108 (in this case - red, green and blue). The colour sub-pixels 108 are spaced apart in a direction along an associated one of the columns 1.04, The facet type portions 68 extend vertically as columns. As indicated above chromatic adjustment is required in order to advantageously cater for the different wavelengths of the colour sub- pixels 108, Figure 27 illustrates a chromatic aberration adjustment portion 126 placed on the rear surface 128 of the body 130 that provides the facet type portions 68.

The chromatic aberration adjustment portion 126 applies a convexity 132 that correlates with a local concavity provided by each of the facet type portions 68 to at least partly counteract chromatic aberration effects provided by the facet type portions 68. As shown in Figure 28 the chromatic aberration adjustment portion 126 spans the column of each facet type portion.

In another embodiment shown in Figure 29 red sub pixels 134 are provided with greater concavity facet type portions 68 in comparison to green sub pixels 1_.36. Blue sub pixels 138 are provided with lesser concavity facet type portions 68 than the green sub pixels 1_.36. This accounts for chromatic effects.

Thus the manipulation of a simple concave Fresnel lens has been discussed. In terms of the lens material it is preferably transparent with high refractive index such as that provided by crown glass. Different sloping facets are used together with a lens portion directly behind to make up a combined faceted prism unit. Light beams passing through each of the faceted prism unit spread out to cover the individual zones of space in front of the lens.

Individual prisms which make up the lens are, in one embodiment, divided into odd and even numbers. The odd prisms are separated from the even prisms and create two separate complimentary Fresnel hemi- lenses.

Light emitting diodes or colour pixels are placed behind the hemi Fresnel lenses. Beams passing through each of the hemi-prisms will have gaps of space between them that are not covered by any light beam. These provide spaces between the viewing positions.

Complimentary Fresnel hemi- lenses are each used transmit light from a single image and the pairs of lenses are used to transmit lights from two different images or left and right images.

By laying two hemi-Fresnel lenses side by side, one finds that at close viewing distances light beams from each hemi lens are displaced laterally by the other hemi lens with gaps between the beams. At a further viewing distance away, when the separation distance between the two adjacent beams is much greater than the displacement distance of the lenses, light beams from the two complimentary Fresnel hemi- lenses effectively recombines to approximate the image transmitted by the original Fresnel lens. The location where the images from the two lenses combines provides the viewing zone of the display.

In creating an auto-stereoscopic display, a set of pixels is laid behind a refracting prism with the back of the prism formed by complimentary hemi Fresnel lenses with pixels from the right image behind the right lens and pixels from the left image behind the left lens. The two hemi-lenses are separated from the pixels or the light source by a small gap of colourless and transparent material with low refractive index such as vacuum, air or common gas such as hydrogen, helium or carbon dioxide. The light beams consequently refract towards the correct target zones as they travels across medium of different refractive indexes. An observer situated at the viewing zone of the two lenses accordingly perceive a single stereoscopic vision of the two pixels.

In modern displays, each pixel is made up of 3 colour sub-pixels. The width of each hemi lens is roughly be equal to the width of one sub-pixel and each pixel will require one Fresnel hemi-lens.

To create a complete image on the display, the hemi-lens of the left image is placed alternately next to the hemi-lens of the right image. That is the lenses of the left set interweave with the lenses of the right set as illustrated.

The lenses in the left set are complementary to those in the right set i.e. the volumes of space illuminated by first set of beams alternate with the volumes of space illuminated by the second set of beams. All the lenses within the same set are identical to each other. The lenses are columnar and, in embodiments, each hemi-lens runs the entire height of the display.

To reduce the number of micro-lenses required and still maintain high resolution, the sub- pixels are stacked vertically rather than horizontally. Beams from the vertically stacked sub-pixels strike a single hemi-lens in front of the pixels with the same angle while beams from horizontally placed sub-pixels will strike the single micro-lens placed in front of them with different angles resulting in mismatching of the viewing targets between the sub- pixels.

The number of facets within each hemi-lens is equal to the number of viewing positions in the viewing zone. A high definition display of 1920 x 1080 pixels with 6 viewing positions will, in embodiments, have 1920 x 6 = 1 1,520 individual columnar facets. Currently the width of each facet could be around 20-40 microns for most displays.

The facets of the micro hemi-Fresnel lenses can be formed by etching or micro-printing. Because all the micro-lenses within the same set are similar, the pattern of the whole lens system will be repetitive. One might manufacture small segments and join them together for larger displays. The micro-printing method holds great promise of short manufacturing time, low cost and suitability for mass production. The time limiting factor may be the creation of the master stamp. Recently available 3D printing technology also presents great possibility in streamlining the lens ' production.

To reduce the complexity in manufacturing the Fresnel hemi-lenses, instead of two distinctive sets of hemi-lenses, one is able to use single set of hemi-lenses as demonstrated. Two identical Fresnel hemi-lenses are then placed behind another prism with two facets angulating at different angles, one facet for each of the two hemi-lenses. In various embodiments, the function of the stereoscopic angulating surface of the second prism is to reflect beams from the left image towards the left visual field and beams from the right image towards the right visual field. The stereoscopic facets are columnar and run the entire height of the display. In this way two identical Fresnel hemi-lenses will act as two complimentary ones.

A convex lens with a focusing surface is, in several embodiments, incorporated into the front surface of the prism whose back houses the stereoscopic facets. The convex lens serves to assist with producing a stereoscopic view of the whole image. Using the convex lens the viewing positions of different pixels within the same set substantially correlates (or superimposes) on the same volumes of space.

After passing through the micro-Fresnel lenses and the stereoscopic surface, beams from the pixels are focussed towards the correct viewing zones by the convex lens. The focal length of the convex surface is equal to the viewing distance. The central beams of all the pixels converge onto the focal point of the lens. The focal point of the lens will also lie on the central viewing position. The deflection ensures that beams from the same set will roughly land in the same viewing positions despite the difference in the horizontal locations of the pixels. In this way auto-stereoscopy of the whole image, not just of individual pixels, is achieved. To reduce the thickness of the display, the convex focussing surface, in embodiments, undergoes a Fresnel transformation to become a Fresnel lens focussing surface.

The vertical placement of different colour pixels behind the same lens produces a chromatic aberration: blue beams will spread out more than red beams. This problem is dealt with by using a set of negative achromatic duplet lenses. Such a lens can be made from high refractive index flint glass with repetitive local convex surface lying in front of the Fresnel hemi-lenses which are made from low refractive index crown glass.

The local convex surface of the flint glass correlates with the local concavity of the Fresnel lenses. In this way the chromatic aberration is at least partially negated.

Another way of dealing with the chromatic aberration is to have separate lenses for each sub-pixel. To correct for the chromatic aberration, the lens for the red sub-pixel needs to have the highest degree of concavity whiles the one for the blue sub-pixel the lowest. If one places the sub-pixels of the same pixel in a vertical column and all the sub pixels with the same colour from different pixels in the same row then all the Fresnel hemi-lenses in the same row will be identical. This method has a higher degree of aberration correction than the achromatic duplet lens and it does not require the construction of the flint glass. However the horizontal Fresnel hemi-lenses are possibly harder to manufacture.

There exists still another aberration problem inherent with this lens system. The deflection of the beams by the focussing surface will not just distort the shape of the viewing zones of the pixels, it will also cause the viewing zones of the outer pixels to broaden. If we choose to match the central beams of the pixels, then there will be a clear stereoscopic image at the central viewing position but a noticeable mismatch of the beams at the outer viewing sites. The mismatch increases as the viewing position moves further away from the central viewing position. This aberration is neither spherical aberration nor field curvature aberration and will be termed 'viewing zone aberration'. This type of aberration cannot be corrected conventionally. To fix the problem, embodiments operate to narrow the viewing zones of the outlying pixels.

In the first method of achieving this, the viewing zones of the outer pixels are narrowed by reducing the local concavity of their hemi-Fresnel lenses as the pixels move away from the centre of the display. The reduction in the concavity of the lenses is substantially proportional to the increase in the pixels' distance from the centre of the display. This can be achieved by having a series of concavities extending from a central pixel. For example inner pixels would have high local concavity (represented by the number 0) while the outer pixels have lower concavities (say represented by numbers +/-3 where the sign represents direction).

In another method the Fresnel hemi-lenses are uniformed and unchanged but vary the local convexity of the flint class 3 at the interface between the flint and crown glass. The part of the lens away from centre has a greater local convex surface than the ones near the centre of the lens. A higher local convex surface of the flint glass will reduce more strongly the spreading effect of the Fresnel hemi-lens. The degree of local convexity of the flint glass is substantially proportional to the distance from the midline of the screen.

In a third method, a diverging GRIN (gradient index) lens is introduced in place of the flint glass lens. The GRIN lens differs from the standard flint glass lens by having a gradient of refractive index with the highest at the edge of the lens and lowest at centre. The local convexity of the GRIN lens and the local concavity of the Fresnel hemi-lenses remain uniformed. Normally, GRIN lenses are used for their focussing or diverging power; in embodiments we are more interested in the interaction between the gradient refractive index, the local convexity of the GRIN lens and the local Fresnel hemi-lenses.

Convexities with high refractive index will reduce the diverging power of the Fresnel hemi- lenses more pronouncedly than convexities with low refractive index. As a result beams passing through the outer part of the display will have smaller spread and narrower viewing zones than beams passing through the more central part. When the viewing zones are focussed by the front focussing surface and subjected to the viewing zone aberration, the viewing positions of different beams will now better correlation than if they have not been modified by the GRIN lens. Due to the diverging power of the GRIN lens itself; as such the focussing surface is provided with a greater degree of convexity to compensate for the divergence of beams by the GRIN lens.

Figures 30 and 31 illustrate an embodiment in which each of facet type portions 68 has a depth 140 that accommodates a single primary colour pixel 10.8. A continuous column spanning the height of all three colour sub-pixels is not provided due to the different concavities of the facet types portions for each sub pixel in a pixel. Figure 32 and 33 illustrate a further embodiment in the form of a lens arrangement 142 for an auto-stereoscopic display that projects to 10 viewing positions 144. The lens arrangement comprises a first surface 1_.46 that includes a plurality of facet type portions 148 for receiving light from a series of pixel groups 150 arranged in pixel group pairs 152. The facet type portions 1_.48 are arranged in series to assist with directing light from the pixel group pairs to the viewing positions _.1_.44.

The lens arrangement 142 includes an opposite surface _.154. The opposite surface 1_.5_.4 is flat. The facet type portions 1_.48 are angled to adopt a nonstandard concavity or convexity that is able to provide: (i) an angulating function for directing light from each pixel group in a pixel group pair to respective left and right visual fields; (ii) a viewing zone function for directing light from each pixel group to a viewing zone; and (iii) an aberration function for limiting chromatic aberration effects of colour sub pixels of the pixel groups.

Notably in the previous embodiments, the final direction of the beam is determined by the combined refraction of a concave Fresnel hemi-lens and a front focusing convex lens. In the embodiment of Figure 32, the refracting power of both lenses is combined into a single Fresnel type lens. Hence, the embodiment shown in Figure 32 provides a 'combined refracting Fresnel lens system' .

As would be apparent the stereoscopic surface can either be incorporated into the combined Fresnel lens or can be a separate lens. In the embodiment of Figure 32, the orientations of the Fresnel facets of the combined lens do not follow a precise concavity or convexity; rather they are dictated by the directions of the viewing targets. Since each columnar facet can only direct light beams onto one target zone, the orientation of each facet will need to be determined individually. The front of the lens system is now planar rather than convex or Fresnel. If one uses a single common columnar facet for all three colour sub-pixels, then a duplet achromatic system could be employed to correct the chromatic aberration. If one uses different facets for each colour sub-pixels, the combined Fresnel lens can be used.

Since the orientation of each facet is individually controlled, it is possible to precisely match the viewing positions of all the pixels within the display. The construction also allows the viewing positions to be placed at any location and not restricted within a specific viewing zone. Referring to Figures 34 to 35 there is provided a lens arrangement 156 according to a further preferred embodiment of the present invention. The lens arrangement 156 provides as an autostereoscopic display 158.

The lens arrangement 156 comprises light directing portions 160 for receiving light from a series 162 of pixel groups 164. The light directing portions 160 comprise a series 166 of slit type providing portions 168 that are able to generate diffraction patterns from the light received from the pixel groups 164.

As shown in Figure 37 the diffraction patterns have alternatively placed maxima 170 and minima 172. The pixel groups _.1_.64 are provided in left-right pixel group pairs 1_.74. The slit type providing portions 78 are each associated with a pair 174 on a one to one basis.

The slit type providing portions 1_.6_.8 in combination with a viewing zone correction portion .1_.7.5 correlate maxima from the pixel groups 1.64 towards the same point in space. The slit type providing portions 1.68 provide a number of slit type portions 1.7.6 in the form of slits 1_.7.6. The number of slits 1.76 associated with a pixel group 1.64 provides the basis for the number of viewing positions in a viewing zone.

Referring to Figure 36 there is provide a first area 17.8 for a right image pixel group 1.8.0 and a second area 182 for a left image pixel group 1.84, In this manner the slit type portions _.168 are provided by series of pairs of slit type areas for providing respective fields of view.

The lens arrangement 156 includes an angulating portion 186 for directing light from each pixel group 164 in a pair 174 of the pixel groups to respective left and right visual fields. The angulating portion 186 is of a similar form to that previously described in relation to the refractive embodiments.

Referring to Figure 38 there is provided an outer viewing position correction 188. The outer viewing position correction 188 increases the further each pixel group is located from the centre of the row in which the pixel group is located. As shown the correction 188 comprises a widening of the slits and an increasing the distance between the slit type areas the further towards the ends of the rows of the pixel group pairs from the centre of the rows.

Again the pixel group pairs 174 are spaced apart into rows and columns; each pixel group of a pixel group pair being in a row next to the other pixel group of the pixel group pair; each pixel group including a pixel having a number of colour sub-pixels; the colour sub- pixels being spaced apart along an associated one of the columns.

Figure 39 provides a simplistic representation of how the maxima project forwardly with the use of the angulating portion 1_,86.

Figure 40 illustrates differently coloured sub pixels. Figures 40 shows how sub pixels of the same colour are located in rows. In addition Figure 40 shows how the slit type providing portions _.168_. provide a chromatic aberration adjustment by there being different associated widths and spacings to align the maxima from differently coloured sub pixels comprising.

Figures 41 to 43 illustrate an alternately shaped angulating portion 190_.that still provides different stereoscopic fields of view to the left and right eye.

Figure 44 illustrates the slit diffraction type method used in the present embodiment. In an alternate embodiment illustrated in Figure 45 and slit type providing portions 1_.68 are provided by a transmissive diffraction grating 192. The transmissive diffraction grating 192 includes a number of concave grooves to provide the grating effect.

In the diffractive type embodiments described, diffraction is used to produce stereoscopic images instead of refraction through Fresnel lenses as with the earlier embodiments.

In the diffractive embodiments light of the diffractive system is produced by laser diodes instead of the standard led. The viewing zone is created within the central maxima of a single vertical rectangular slit diffraction pattern as shown. The maxima of the vertical slit roughly has a horizontally aligned rectangular shape.

The horizontal boundary of the viewing zone is defined by the width of the central maxima of the single rectangular slit and is given by: width of viewing

Where:

λ is the wavelength

D is the viewing distance or the distance between the screen and the viewing zone. a is the width of the slit

The laser diodes are placed behind a diffraction grating of rectangular slits. Light beams from the grating will generate alternately placed maxima and minima. Visual fields of the viewing positions are located at the maxima. The distance between two adjacent maxima or viewing positions within the viewing zone is given as: distance between two viewing positions ~ λϋ/Α

Where:

λ is the wavelength

D is the viewing distance or the distance between the screen and the viewing zone.

A is the distance between two adjacent slits.

The arrangement is configured so that all the maxima superimpose on the same locations in space. To achieve this feat the lens arrangement is configured to make several corrections as previously described. In this manner the observer to sees a clear picture

Colour pixels made from laser diodes which are situated behind a diffraction grating. Lights passing through the grating will spread out into the viewing maxima. As mentioned previously, the width of the slits determines the width of the viewing zone while the distance between the slits controls the viewing positions. A narrower slit will lead to a wider viewing zones and a smaller distance between the slits will increase the separation between the viewing positions.

Lying in front of the diffraction grating is a transparent lens. The back surface of this lens has an undulating pattern of stereoscopic facet pairs with a slight angulation between the paired facets. The stereoscopic facets are columnar and they run through the entire height of the display. Each of the columnar facets receives lights from a single column of colour pixels and each stereoscopic facet pair separates light from two adjacent pixel columns to two neighbouring visual fields in the same way as the refractive display. The front surface of the lens is a Fresnel convex lens with its facets running vertically through the whole height of the display. Its main function is to focus the maxima from all the pixels towards the correct viewing positions.

Similar to the refractive system, there is a diffractive chromatic aberration. Since the width of the viewing zone and the separation of the viewing maxima positions are wavelength dependent, the viewing maxima of the red beams will not match those of the blue beams. The difference in the spreads of the beams also causes variation in light intensity at the viewing maxima for different colours.

To correct the diffractive chromatic aberration, different gratings for different colours are provided. Red pixels use a grating with wider slits and greater slit distance while blue pixels use gratings with narrower slit width and closer spacing. The green pixels to use intermediate grating. The set up can be realised by having all pixels in the same row to have the same colour and the grating is uniformed within each row but different with the gratings of the adjacent rows. This design is similar to the Fresnel hemi-lenses of the refractive system with the vertically stacked sub pixels.

Alternatively, it is possible to place the sub-pixels of the same pixel in a horizontal row and all the sub pixels with the same colour from different pixels in the same column (See Figures 41 to 43). We now have the same grating running through the entire height of the display. Since the stereoscopic pixel pair is now placed vertically, the stereoscopic surface will also need to be vertical. It means that there is only one surface angulation for all the pixels in the same row but different angulations for pixels between alternate rows. The various Figures shows the geometry of the stereoscopic surface with the diffraction grating removed. In this design, the manufacturing process for the diffraction grating is more straightforward but for the stereoscopic surface is more complex.

There still remains the 'viewing zone aberration' caused by the outwardly facing focussing surface. This is due to the same problem encountered in the refractive display: altering the paths of light beams will distort their geometry and the viewing zones of the pixels. To counter this problem, the same process of narrowing the width of the pixels' viewing zones and their maxima substantially in proportion with the distance between the location of the pixels and the centre of the display. This task can be achieved by widening the each slit's width and the distance between the slits. The degree of the increasing in the slits' width and separation is proportional to the distance from the centre of the display.

The transmissive-diffractive display has the advantage of power efficiency. In a standard slit diffraction grating, the narrow slits are placed far apart from each other and light beams are only allowed to pass through the slits but not between them. It means that for each bundle of light passing through the slits, much greater amount of the light energy is blocked by the diffraction grating. Such a setup has lower energy efficiency compared with the refractive display.

Advantageously using a transmissive diffraction grating instead of the conventional slit diffraction grating addresses this problem. Notably the front surface of the transparent lens of a conventional transmissive diffraction display is made up of a large number of concave grooves. The width of each groove is much larger than the width of the slits in the diffraction grating and it is roughly equal to the distance between the slits. Since the width of the groove is large compared to the wave length of the light beams, the broadening of the beams is primarily determined by the refraction of light at the concave surface of the groove and only a small amount of beam spreading is caused by the diffraction. The degree of concavity of the groove determines the amount of widening of the beams or the width of viewing zones while the breadth of the grooves determines the separation distance of the viewing positions. This setup allows all light beams from the pixels to pass through the diffraction grating and gives us more flexibility in placing the viewing positions. It is also provides more even light density distribution in the viewing zone than the maxima from a single slit.

Referring to Figures 46 to 50 (an in particular Figure 48) there is shown a lens arrangement 194 according to a further preferred embodiment of the present invention. The lens arrangement 194 includes a series _,196 of viewing zone correction portions _,198. Referring to Figures 48 and 49, the viewing zone correction portions 198 are able to provide a number of views to different viewing zones 200 associated with different viewing groups. As before there is provided a series of pixel groups (not shown) that are arranged into rows 202. As before, the views are formed by directing light from the pixel groups.

In the embodiment the viewing zone correction portions _.198 each comprise a series 204 of viewing zone lenses 206. Each row 202 of the pixel groups is associated with a corresponding series 204. Each viewing zone lens 206 is accordingly associated with a row 202 of the series of pixel groups.

Referring to Figure 46 each series 204 of the viewing zone lenses 206 comprises the thickness the corresponding row. Each viewing zone lens 206 of a series 204 is associated with a different viewing zone. Refereeing to Figures 48 and 49 each viewing zone lens _,206 of each series 204 is associated with a viewing zone having a different viewing height.

Each series 204 of the viewing zone lenses 206 comprises a series 204 of refractive type lenses. Referring in particular to Figure 50, each refractive type lens 206 is angled on its forward surface 208 to direct the light to a viewing height associated with the viewing zone.

Referring to Figure 51 , each viewing zone refractive type lens _.1_.0 includes a number of facet type portions 210 on an outwardly facing surface 212 that are inset to provide a reduced thickness.

Notably the system is well suited to a radial type cinema environment where rows are provided at different heights (See Figure 52). In the case of a liner cinema environment as shown in Figure 53, having a facet type autostereoscopic arrangement (as described), the facet type portions are able to direct light with increased widening from a top back viewing zone to a bottom front viewing zone. This is illustrated in Figures 54 and 55 wherein the concavity of the facet type portions is varied.

Figure 56 shows an embodiment where a gradient lens 214 having a repetitive horizontal refractive gradient produces localised convex lens in front of each of the concave lens 216. The localised convexity works to reduce the chromatic aberration between colour sub- pixels. The lens 2_.14 also has a vertical refractive index gradient for each colour sub-pixels with the top portion has a higher refractive index than the lower portion. The pattern is repetitive vertically. The vertical gradient works to modify the physical attribute of the convex lens. Namely, the top portion of the lens in front of the top part of the colour sub- pixel will have a higher convexity while the lower portion of the lens in front of the lower part of the colour sub-pixel will have a lower convexity. Since the lens 214 negates the effect of the concave Fresnel lens to an extent, the beams from the top of the colour sub- pixels will be narrower while beams from the bottom part will spread out wider

Figure 57 shown a lens 218 that takes this one step further in that the lens is used to replace both the achromatic duplet lens and the Fresnel lens. Similar to the previous embodiment, the GRIN lens has both horizontal and vertical refractive gradient. The horizontal gradient however is not continuous but rather disrupted to form a series of vertical stripes with short refractive index gradients designed to mimic the attribute of the concave Fresnel lens.

The vertical component has a primary refractive index gradient in front of each colour sub- pixel with the top part having a lower refractive index than the bottom part. After passing through the complex GRIN Fresnel lens, beams from the top of the colour sub-pixel will be narrower than beams from the bottom of the pixel.

The complex GRIN lens depicted in Figure 57 also has a secondary vertical gradient which spreads across all three colour sub-pixels and superimposes on the primary vertical gradient with the refractive index in front of the blue colour sub-pixel to be smaller than the refractive index in front of the green pixel which is in turn less than the refractive index in front of the red pixel. This secondary vertical gradient works similarly to achromatic duplet lens and counteracts the chromatic aberration.

To the best of the applicant's knowledge, there has not been any attempt to manufacture a complex GRIN lens. However it is considered that the construction of such a lens is not necessarily beyond current technology.

Referring to Figure 58 the increased widening could be proved by a diffractive gradient 220. In various embodiments the series of viewing zone lens comprise could comprise a series of diffraction grating lenses having different spacing 's and thicknesses.

Whereas other embodiments are sufficient for home viewing where the observers are located at roughly the same distance from the display, the multi-zone lens systems described advantageously provide for viewing at different distances from the screen such as the rows inside a cinema.

The conventional problem arises due to a display being created by the crossing of the pixels' beams through the same vertical plane in a specific pattern. For this reason, conventionally, at the space in front and behind the plane of crossing where the beams are no longer spatially coordinated, there is no autostereoscopy. It means that the viewing zone has a restricted depth; viewers situated in front or behind the viewing zone will not be able to see a 3D image.

The distance between the viewing zone and the display is determined by the degree of convexity of the focussing surface. Increasing the convexity shortens the viewing distance. In order for the display to have multiple viewing zones, the focussing surface of each sub- pixel has a set of lenses with different degrees of convexity. Each convex lens, in embodiments, runs the entire width of the display and will direct light into one single primary viewing zone. The number of the convex lenses in each set is equal to the number of the viewing zones. The thickness of one single set of focussing convex lenses is equal to the thickness of one single sub-pixel. The focussing surface can be a standard smooth surface or can be Fresnel facets.

If the viewing zones are in the same horizontal plane, then light beams from one zone will cross into another and interfere with the formation of 3D image in these zones. In order to avoid the crossing over of beams from different zones, the viewing zones located at different heights. This happens to be the seating arrangement in most cinemas and theatres. Furthermore, the focussing facets must also be arranged in the same vertical order as their correspondent viewing zones. For example the bottom facet will project beams to the lowest row of viewers while the top facet will illuminate the top row.

To ensure the beams reaching the correct viewing zones which now have different distance and height values or different z and y co-ordinates relatives to the display, the horizontal facets of the focussing surface has not just correct convexity, but also correct inclinations to deflect the beams to the proper heights. As such the degree of tilting of the horizontal facets of the focussing surface will vary according to the positions of the target zones relative to the lenses. As would be apparent there is a difference in the inclination of the lenses used for the top and the bottom pixel rows.

As indicated above projecting images onto viewing zones that do not have a radial seating arrangement is a common issue because most cinemas or theatres utilise the more popular arrangement of the linear or rectangular seating.

In order for the pixels to project onto the linear seating arrangement, spreading of the beams is widened as they move forwards from the top back viewing rows to the bottom front viewing rows. This effect can be easily achieved with the diffractive display by dividing the grating in front of the pixel into even smaller rows; the number of grating rows per pixel is equal to the number of seating rows. The diffraction grating at the higher rows will have wider slits and greater slit separation than the grating in the lower rows as illustrated. Beams projected through the top grating rows will be narrower and refracted by the top focussing rows towards the top back viewing seats while beams projected through the bottom grating rows will be wider and will be refracted by the bottom focussing rows towards the bottom front viewing seats.

In the Fresnel lens each pixel in the refractive display is divided into many smaller rows with the number of the Fresnel rows equal to the number of viewing rows. The concavities of the top Fresnel rows are less than those of the lower rows as illustrated. Beams passing through the bottom Fresnel rows will spread out wider before refracted towards the bottom front viewing seats while beams passing through the top Fresnel rows will be narrower and refracted towards the top back viewing seats.

More advanced embodiments of the same concept use complex GRIN lenses. Firstly, a GRIN lens is a suitable replacement for the achromatic duplet lens. In arrangements the GRIN lens has a repetitive horizontal gradient of refractive index to produce localised convex lens in front of each of the concave Fresnel lens. The convex GRIN lenses work to reduce the chromatic aberration between colour sub-pixels. Unlike a normal GRIN lens however, the complex GRIN lens also has a vertical refractive index gradient for each colour sub-pixel with the top portion has a higher refractive index than the lower portion. The pattern is repetitive vertically. The vertical gradient works to modify the physical attribute of the convex lens: the top portion of the lens in front of the top part of the colour sub-pixel will have a higher convexity while the lower portion of the lens in front of the lower part of the colour sub-pixel will have a lower convexity. Since the convex GRIN lens negates the effect of the concave Fresnel lens, the beams from the top of the colour sub-pixels will be narrower while beams from the bottom part will spread out wider.

The concept of complex GRIN lens can even be taken one step further. In one embodiment, the GRIN lens is used to replace both the achromatic duplet lens and the Fresnel lens. Such a GRIN lens has both horizontal and vertical refractive gradient. The horizontal gradient however is not continuous but rather disrupted to form a series of vertical stripes with short refractive index gradients designed to mimic the attribute of the concave Fresnel lens. The vertical component has a primary refractive index gradient in front of each colour sub-pixel with the top part has a lower refractive index than the bottom part. After passing through the complex GRIN Fresnel lens, beams from the top of the colour sub-pixel will be narrower than beams from the bottom of the pixel. The complex GRIN lens depicted also has a secondary vertical gradient which spreads across all three colour sub-pixels and superimposes on the primary vertical gradient with the refractive index in front of the blue colour sub-pixel to be smaller than the refractive index in front of the green pixel which is in turn less than the refractive index in front of the red pixel. This secondary vertical gradient works similarly to achromatic duplet lens and counteracts the chromatic aberration.

To the best of the applicant's knowledge, there has not been any attempt to manufacture a complex GRIN lens. However the construction of such a lens is not necessarily beyond our current technology.

Figure 59 illustrates a lens arrangement 222 according to a further preferred embodiment of the present invention. The lens arrangement 222 includes facet type portions that are inset to provide a reduced thickness, the facet type portions being arranged in series for forming stereoscopic images from a series of pixel group pairs. The facet type portions are angled to adopt a nonstandard concavity or convexity that is able to provide: (i) an angulating function for directing light from each pixel group in a pixel group pair to respective left and right visual fields; (ii) a viewing zone function for directing light from each pixel group to a number of different viewing zones each associated with different heights; and (iii) an aberration function for limiting colour aberration effects of colour sub pixels of the pixel groups. The figures shows the difference in the surface geometry of the top left micro-lens and the central micro-lens of the display as seen from four different views.

The embodiment provides a Multi-zone Fresnel lens system combing the concave Fresnel hemi-lens, the stereoscopic surface (the angulating portion) and the front focusing convex lens into a single multi-zone Fresnel lens. The lens portion in front of each pixel has individualized facets. The orientations of the Fresnel facets are dictated by the directions of the viewing targets. The orientation of each facet will need to be determined individually in order to direct light beams onto the correct target zone. The front of the lens system is now planar rather than convex or Fresnel. The single Fresnel lens system is advantageously thin. Calculation of the orientation of each facet is quite straight forward but it may require a rather powerful computer due to a large number of facets required for the multi-viewing zone display. The Figures shows the difference in the surface geometry of the top left micro-lens and the central micro-lens of the display as seen from four different views.

Since this display is to be used in a cinema setting, the screen size will be quite large. The width of the micro-facet could be around 50 microns or around half the thickness of a human hair. It is presently not possible to micro-print a 10-20 meter screen with a very large number of micron sized facets. Breaking the screen into smaller segments of around 10-20cm and re-join them to form the larger screen may be a way of addressing this.

Referring to Figure 60 there is shown a lens arrangement 224 according to a further preferred embodiment of the present invention. The lens arrangement 224 provides an autostereoscopic display comprising: a number of light directing portions 226 for receiving light from a series of pixel groups 228. Each pixel group 228 contains four pixels 230 (number N) where each pixel 230 of a pixel group 228 is provided for use in forming a different view as part of the display. The pixel groups 230 are able to provide N different views at any one time.

Figure 60 illustrates five pixel groups 228. Each of the pixel groups 228 include a first pixel 232, a second pixel 234, a third pixel 236 and a fourth pixel 238. The light directing portions 226 are able to direct light from the pixels 232 to 236 to four sub-positions 240.

As shown in Figure 61 : the first pixels 232 of the pixels groups 228 are directed to a first sub-position 242, the second pixels 234_...of the pixels groups 22_.8 are directed to a second sub-position 24_.4, the third pixels 236of the pixels groups 230 are directed to a third sub- position 246,_. the fourth pixels 238 of the pixels groups 230 are directed to a fourth sub- position 248. The sub-positions .240 are advantageously sub-positions of viewing positions ISO- Referring to Figure 61 the viewing position 250 are separated a pupillary distance 252 to provide a first viewing position 254, a second viewing position 256 and a fourth viewing position 258.

Referring to Figure 6.1, the light directing portions 22.6 comprise facet type portions 2.6.0 that are each associated with a pixel 232jo_238 of a pixel group 228 on a one to one basis for directing light from the pixel group to the four sub positions 250. The manner in which the facet type portion 260 operate has been previously described. The lens arrangement 224 will be seen to provide a parallactic auto-stereoscopy display for stationary observers. The minimal number of positions from which a person can perceive a symmetrical parallax (parallax from moving to either left or right side) is three positions or four different images. As shown in the Figures the concept applies to the parallax viewing of a single dice from three different positions or perspectives. This basic form of parallax often occurs when the observe stands or sits in one place but the head moves slightly from side to side. An autostereoscopic display which can generate even with such a minimal parallax can offer a vastly more realistic viewing experience than the one which can only show a single stereoscopic view.

Parallax describes the difference in the apparent positions of objects viewed from two different locations. Stereoscopic vision could be considered as a special form of parallax due to the fact that the observer receives two different images from two different locations; for most cases however stereoscopy is considered to be the viewing from a single position.

To generate four different images for a three perspective parallax we will need four separate sets of pixels instead of just two as in the case of the standard auto-stereoscopy. Each of the pixel sets will show a slight different image of the same object(s). Each parallactic pixel will have four standard pixels or 12 sub-colour pixels.

Each parallax viewing position is composed of 3 standard viewing positions and as such will receive light from all four sets of pixels. Within each parallactic pixel, the four standard pixels are always placed in the correct order of the parallax view and their projections within each parallax viewing positions also follow the same order.

Under normal viewing condition, the observer will sit in the middle of the seat at the viewing position and his/her right eye will see image II while the left eye will see image III. When the observer moves to his/her right into the viewing position 1 , the right eye will see image I and the left eye will see image II. When the observer moves to his/her left into the viewing position 3, the right eye will see image III and the left eye will see image IV. The parallax images are the same for all parallax viewing positions. The triple perspective viewing display will have twice the number of standard pixels as compared to the single perspective autostereoscopic display. The diffractive display is suited for this embodiment. The stereoscopic surface 262 now becomes a parallactic surface as illustrated by Figure 61. Instead of having 2 facets (one for left image and one for right image), the parallactic surface has 4 distinctive facets to project four different adjacent images required to generate 3 viewing positions. The pattern of the four different facets is regularly repeated through the whole parallactic surface.

The distance between two interference maxima of the same pixel at the viewing positions should be roughly equal to 12cm or twice the average pupillary distance while the distance between two adjacent interference maxima of a stereoscopic pair should be equal to the average pupillary distance. In order to have a clean image of the pixels' projection, there are provided about 6-7 slits per pixels. For small displays with small pixel sizes, the slit distance will be small, the maxima separation will be large and the viewing distance will be short. For a large display with large pixel size, the slit distance will be greater, the maxima separation will be smaller and the viewing distance will be proportionately longer.

The parallax experience is enhanced by increasing the number of perspectives or pixel sets, together with a concomitant reduction in the width of the visual field at the viewing positions.

Thus three viewing positions are provided for an autostereoscopic display as illustrated in Figure 62. The Figure illustrates how intermediate Left/Right images are provided at the same sub-position where each sub-position is separated by a pupillary distance.

Referring to Figure 63 there is provided a lens arrangement 264 according to a further preferred embodiment of the present invention. The lens arrangement 264 includes a number of light directing portions 266 arranged in series for receiving light from a series of four pixel groups 268. Each of the pixel groups 268 contains five pixels 270. . Each pixel 270 is provided for forming a different view as part of an autostereoscopic display. The pixel groups 268 are able to provide N different views at any one time.

Advantageous there are provided four viewing positions. Each viewing position (M=l to 4) is associated with a view M and a subsequent view M+l (represented as I to V in Figure 63 where M =1 to IV) to advantageously provide autostereoscopy for a moving observer.

Referring to Figure 64 the light direction portions 266 comprise facet portions 272. Each pixel 27_.0 is associated with one or two facet portions 272. Each facet portion 272 is associated with a single pixel .270. More particularly, the pixels 270 in each pixel group 268_. are arranged in series; the first and last pixel in each series (pixel 274 and pixel 276) are associated with a single one of the facet portions 272. The other pixels 270 are associated with two facet portions 272. The facet portions .270 are provided on a stereoscopic surface 278.

As shown in Figure 63, the facet portions 272 are able to direct light to four viewing positions 280. Each viewing position is associated with a pair of sub-positions 282 to which light is directed by the facet portions 272. The pairs of sub-positions 282 are separated by a pupillary distance for stereoscopic viewing.

The embodiment provides parallactic autostereoscopy for mobile observers. As the viewer moves across the display the parallax images vary with the viewing positions and the images provided create the illusion of moving parallax according to the following relationship:

n_images=n_(viewing positions)+l From the above equation, five different images or five set of pixels are created for the four viewing positions. As the observer walks across from the left to the right of the display, he or she will first see the stereoscopic picture of images I and II at the position 1. At position 2, the observer will see the combined image of II and III. At position 3, it will be the stereoscopic image of III and IV. Finally at position 4, the observer will perceive the stereoscopic image of IV and V. In this way a moving observer will perceive a gradual change in the perspective or a parallax perception of the image.

In order to have different images at different positions, the pixels will need to project in a different way to the pixels of the display for the stationary observer. The display requires five image sets which are numbered from I to V. The sets show images in the parallax sequence from left to right. Each parallactic pixel will therefore need to have five standard pixels or 15 colour sub pixels. The first pixel, pixel I of each parallactic pixel, projects only to the observer's right visual field at the first viewing position; while the last pixel, pixel V of each parallactic pixel, projects only to the observer's left visual field at the last viewing position. For all other pixels, each will project its beam to the observer's right visual field at the correspondently numbered viewing position and to the observer' left visual field of the immediately preceding viewing position. The example the pixel II projects its beam to right visual field of viewing position 2 and the left visual field of viewing position 1. As would be apparent beams from pixel III will travel to right visual field of viewing position 3 and left visual field of viewing position 2. Similarly beams from pixel IV will travel to right visual field of viewing position 4 and left visual field of viewing position 3. In this way, an observer travelling from left to right will perceive sequential, stereoscopic and parallactic images. A larger number of viewing positions of pixel sets will produce a more realistic parallax experience. When the number of viewing positions reaches a value at which the width of the projection of each pixel is equal to or less than the average pupillary distance and there is no gap between the visual fields, then the parallax will be observed by both stationary and moving observers.

The refractive display suited embodiment. In this setup, all pixels except for the first and last project their beams to only two points in space. The stereoscopic surface now becomes parallactic surface. Since pixels I and V project to only a single visual field in space while pixels II, III and IV project to two different visual fields, each parallactic pixel will project in total to eight different visual fields. If the colour sub pixels of each standard pixel are arranged vertically, then for each parallactic pixel, the parallactic surface will now have eight distinctive facets to project five different adjacent images required to generate 4 viewing positions. The pattern of eight facets forms a simplified Fresnel concave surface. The pattern is regularly repeated through the whole parallactic surface. The Fresnel hemi lens is no longer required because the parallactic surface has now taken over its function. Methods to counteract various chromatic and viewing zone aberrations are the same as for the autostereoscopic refractive display but now applying to the parallactic surface instead of the Fresnel hemi-lens.

The data required for parallactic displays with a large number of perspectives is extremely high and it has been a major stumbling block in the past in finding the method to store as well as to manufacture a transistor powerful enough to process the enormous amount of data in a short time frame. With the current high storage capacity of the Blu-ray disc, storing the data is not much of an issue. It leaves us with a possible processing problem. Fortunately the nature of the present invention provides a simple solution to this predicament. Since each viewing perspective of an object or scenery is a complete set of images, it follows that each image set can be processed by a single processor or a large number of viewing perspective can be shared between multiple processors. The only requirement for this set up to work is a mean to synchronise the correspondent frames of different image set from different processors so that they can be displayed at the same time. This can easily be done by connecting all the processors to the same clock. In this way a parallactic display with a high number of perspectives can be built with the current technology.

Figure 66 illustrates a method 284 according to a further preferred embodiment of the present invention. The method 284 advantageously provides number of viewing positions for an autostereoscopic image. At block 286, the method 2_.84 includes projecting light from 5 sets of pixels, each set of pixels providing a different view of the stereoscopic image. At block 288 the method 284 includes directing the light to 8 sub-positions .290 to provide 4 viewing positions 2_.9_.2 . Each viewing position M is associated with a view M and a subsequent view M+l for M=l to 4 to provide autostereoscopy for a moving observer.

The following table of terms is provided as part of the specification. The reader is however to use appropriate judgment when the terms are used in particular contexts.

1 pixel = 3 sub-pixels The two terms are used interchangeably and are only specified clearly when the need arises. A sub pixel is of course a pixel.

1 stereoscopic pixel A stereoscopic pixel pair can be considered as a pixel for the pair = 1 left pixel + 1 left eye and a pixel for the right eye in the formation of a right pixel stereoscopic image.

1 parallactic pixel = n A parallactic pixel contains multiple standard pixels, the pixels pixels. forming at least one stereoscopic pixel pair.

Left and right pixels Left and right pixels, as well as left and right images, are generally described from the viewer's perspective. The definition of left and right is however a subjective one. Viewing zone The viewing zone is a general area of space containing the viewing positions.

Viewing positions The viewing positions are localized space where each observer can perceive stereoscopic images.

Visual field The visual field is the left or right viewing space within each viewing position.

Stereoscopic images At least two images that represent the same scene form a different view.

As would be apparent, various alterations and equivalent forms may be provided without departing from the spirit and scope of the present invention. This includes modifications within the scope of the appended claims along with all modifications, alternative constructions and equivalents.

There is no intention to limit the present invention to the specific embodiments shown in the drawings. The present invention is to be construed beneficially to the applicant and the invention given its full scope.

In the present specification, the presence of particular features does not preclude the existence of further features. The words 'comprising', 'including' and 'having' are to be construed in an inclusive rather than an exclusive sense.

It is to be recognised that any discussion in the present specification is intended to explain the context of the present invention. It is not to be taken as an admission that the material discussed formed part of the prior art base or relevant general knowledge in any particular country or region.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS :

1. A lens arrangement for an autostereoscopic display comprising: a series of facet type portions for receiving light from a series of pixel groups; the facet type portions being arranged in the series to assist with directing the light from the pixel groups to a number of viewing positions.

2. A lens arrangement as a claimed in claim 1 wherein the facet type portions face towards the pixel groups and at least some of the facet type portions are inset by extending inwardly to provide the lens arrangement with a reduced thickness.

3. A lens arrangement as claimed in claim 1 , 2 or 3 wherein there are provided pairs of facet portions, each facet type portion of a pair of the facet type portions being offset by a predetermined distance and being of different angularity to encourage convergence of the associated light beams in a viewing zone.

4. A lens arrangement as claimed in claim 1 , 2 or 3 wherein the facet type portions are provided in the series +/- (-5, -3, -1 , +2, +4, +6), wherein: (i) the positive integer 1 represents a base angularity facet type portion; (ii) higher integers represent higher angularity facet type portions; and (iii) negative integers represent a mirrored angularity of the facet type portion associated with the positive version of the integer.

5. A lens arrangement as claimed in claim 1 , 2 or 3 wherein the facet type portions are provided in the series +/- (2x-l for x=-N to 0; followed by 2x for x=l to N+1) wherein: (i) the positive integer 1 represents a base angularity facet type portion; (ii) higher integers represent higher angularity facet type portions; and (iii) negative integers represent a mirrored angularity of the facet type portion associated with the positive version of the integer.

6. A lens arrangement as claimed in claim 1 , 2 or 3 wherein the facet type portions are provided in the series +/- (2x-l for x=-N to 0; followed by 2x for x=l to N+l ; followed by 2x-2 for x=-N to 0; followed by 2x-l for x=l to N+l) wherein: (i) the positive integer 1 represents a base angularity facet type portion; (ii) higher integers represent higher angularity facet type portions; and (iii) negative integers represent a mirrored angularity of the facet type portion associated with the positive version of the integer.

7. A lens arrangement as claimed in claim 1, 2 or 3 wherein a concave surface is divided into portions wherein the portions are represented as x for x=-M to - 1 followed by x for x=l to M from one end to the other provides the basis of the curvature of the facet type portions; the facet type portions being provided in the series +/- (2x-l for x=-N to 0; followed by 2x for x=l to N+l ; followed by 2x-2 for x=-N to 0; followed by 2x-l for x=l to N+l) wherein: (i) the positive integer 1 represents a base angularity facet type portion; (ii) higher integers represent higher angularity facet type portions; and (iii) negative integers represent a mirrored angularity of the facet type portion associated with the positive version of the integer.

8. A lens arrangement as claimed in any one of claims 1 to 7 wherein along the series of the facet type portions, the facet type portions are arranged to skip a angularity range that is later provided a predetermined distance away from the position at which the angularity range is skipped.

9. A lens arrangement as claimed in any one of claims 1 to 8 wherein the facet type portions are arranged in a series of pairs of lens arrangement portions; the lens arrangement portions being spaced apart.

10. A lens arrangement as claimed in claim 9 wherein the pixel groups are arranged in a series of pairs and each pair of lens arrangement portions accommodates one or more of the pairs of pixel groups.

11. A lens arrangement as claimed in claim 10 wherein in each pair of pixel groups a first pixel group provides for a first field of view and the other pixel group, in the pair, is provided for providing a second field of view.

12. A lens arrangement as claimed in claim 11 wherein in each pair of pixel groups, the pixel groups, are arranged one after the other to form a length and the pair of lens arrangement portions accommodating the pair spans the length.

13. A lens arrangement as claimed in any one of claims 9 to 12 wherein the number of facet type portions is the same in each lens arrangement portion and provides the basis for the number of viewing positions, the viewing positions being provided in a viewing zone.

14. A lens arrangement as claimed in any one of claims 9 to 13 wherein each lens arrangement portion of a pair of lens arrangement portions is asymmetrical and comprises a mirror image of the other lens arrangement portion in the associated mid-plane.

15. A lens arrangement as claimed in any one of claim 1 to 14 wherein the pixel groups are arranged in a series of pairs and the arrangement includes an angulating portion for directing light from each pixel group in a pair of the pixel groups to respective left and right visual fields.

16. A lens arrangement as claimed in claim 15 wherein the angulating portion includes at least one facet type angulating portion spanning the width of each pixel group pair.

17. A lens arrangement as claimed in claim 16 wherein the facet type angulating portions form a v-shaped channel, the pixel group pairs being arranged side by side to face opposite sides of the v-shaped channel.

18. A lens arrangement as claimed in any one of claims 15 to 17 wherein the angulating portion includes an inner portion and an outer portion, the inner portion for directing light from each pixel group in a pixel group pair to respective left and right visual fields; and the outer portion for providing a viewing zone correction portion for directing light originating from the pixel group pairs towards a viewing zone, the viewing zone correction portion having a number of facet type correction portions that are inset to provide a reduced thickness of the viewing zone correction portion.

19. A lens arrangement as claimed in any one of claims 1 to 17 including a viewing zone correction portion for directing light from pairs of the pixel groups, towards a viewing zone, the viewing zone correction portion having a number of facet type correction portions that are inset to provide a reduced thickness of the viewing zone correction portion.

20. A lens arrangement as claimed in any one of claims 1 to 18 wherein each facet type portion is associated with a different viewing position within a viewing zone.

21. A lens arrangement as claimed in any one of claims 1 to 19 wherein the pixel groups are arranged into a series of pixel group pairs; the pixel group pairs being arranged into rows and columns; each pixel group of a pixel group pair being in a row next to the other pixel group of the pixel group pair.

22. A lens arrangement as claimed in claim 20 including an outer viewing position correction for narrowing the viewing positions; the outer viewing position correction serving to narrow a concavity of the facet type portions.

23. A lens arrangement as claimed in claim 21 wherein the outer viewing position correction increases the further each pixel group is located from the centre of the row in which the pixel group is located.

24. A lens arrangement as claimed in claim 21 or 22 wherein the outer viewing position correction comprises a diverging gradient index portion having a refractive index that increases towards the ends of the rows of the pixel group pairs from the centre of the rows.

25. A lens arrangement as claimed in any one of claims 18 to 23 including a chromatic aberration adjustment that correlates with a local concavity provided by each of the facet type portions to at least partly counteract chromatic aberration effects provided by the facet type portions;

26. A lens arrangement as claimed in any one of claims 1 to 24 wherein the pixel groups are arranged into a series of pixel group pairs; the pixel group pairs being spaced apart into rows and columns; each pixel group of a pixel group pair being in a row next to the other pixel group of the pixel group pair; the lens arrangement including a chromatic aberration adjustment that correlates with a local concavity provided by each of the facet type portions to at least partly counteract chromatic aberration effects provided by the facet type portions; the chromatic aberration adjustment spanning the column of each facet type portion.

27. A lens arrangement as claimed in any one of claims 1 to 25 wherein the pixel groups are arranged into a series of pixel group pairs; the pixel group pairs being spaced apart into rows and columns; each pixel group of a pixel group pair being in a row next to the other pixel group of the pixel group pair; each pixel group including a pixel having a number of colour sub-pixels; the colour sub-pixels being spaced apart along an associated one of the columns.

28. A lens arrangement as claimed in claim 26 including a chromatic aberration adjustment portion that correlates with a local concavity provided by each of the facet type portions to at least partly counteract chromatic aberration effects provided by the facet type portions; the chromatic aberration spanning the column of each facet type portion.

29. A lens arrangement for an autostereoscopic display comprising: a series of facet type portions for receiving light from a series of pixel groups arranged in pixel group pairs; the facet type portions being arranged in series to assist with directing light from the pixel group pairs to number of viewing positions.

30. A lens arrangement as claimed in claim 28 wherein the facet type portions are angled to adopt a nonstandard concavity or convexity that is able to provide: (i) an angulating function for directing light from each pixel group in a pixel group pair to respective left and right visual fields; (ii) a viewing zone function for directing light from each pixel group to a viewing zone; and (iii) an aberration function for limiting chromatic aberration effects of colour sub pixels of the pixel groups.

31. A lens arrangement as claimed in claim 28 or 29 having a flat outwardly facing surface and inwardly facing surface providing the facet type portions.

32. A lens arrangement for an autostereoscopic display comprising: light directing portions for receiving light from a series of pixel groups; the light directing portions comprising a series of slit type providing portions able to generate diffraction patterns from the light received from the pixel groups, the diffraction patterns having alternatively placed maxima and minima.

33. A lens arrangement as claimed in claim 32 wherein the slit type providing portions are arranged to correlate maxima from the pixel groups towards the same point in space.

34. A lens arrangement as claimed in claim 32 or 33 wherein the number slit type portions associated with a pixel group provides the basis for the number of viewing positions in a viewing zone.

35. A lens arrangement as claimed in claim 32, 33 or 34 wherein the slit type portions are provided by series of pairs of slit type area for providing respective fields of view.

36. A lens arrangement as claimed in any one of claims 32 to 35 wherein maxima provided by slit type areas are associated with a different viewing positions within a viewing zone.

37. A lens arrangement as claimed any one of claims 32 to 36 wherein the pixel groups are arranged in a series of pairs and the arrangement includes an angulating portion for directing light from each pixel group in a pair of the pixel groups to respective left and right visual fields.

38. A lens arrangement as claimed in claim 37 wherein the angulating portion includes at least one facet type angulating portion spanning the width of each pixel group pair.

39. A lens arrangement as claimed in claim 38 wherein the angulating facet type portions form a v-shaped channel, the pixel group pairs being arranged side by side to face opposite sides of the v-shaped channel.

40. A lens arrangement as claimed in any one of claims 37 to 39 wherein the angulating portion includes an inner portion and an outer portion, the inner portion for directing light from each pixel group in a pixel group pair to respective left and right visual fields; and an outer portion for providing viewing zone correction portion for directing light originating from the pixel group pairs towards a viewing zone

41. A lens arrangement as claimed in claim 40 wherein the viewing zone correction portion has a number of facet type correction portions that are inset to provide a reduced thickness of the viewing zone correction portion.

42. A lens arrangement as claimed in any one of claims 32 to 41 wherein the pixel groups are arranged into a series of pixel group pairs; the pixel group pairs being spaced apart into rows and columns; each pixel group of a pixel group pair being in a row next to the other pixel group of the pixel group pair.

43. A lens arrangement as claimed in claim 42 wherein including an outer viewing position correction that increases the further each pixel group is located from the centre of the row in which the pixel group is located.

44. A lens arrangement as claimed in claim 42 wherein the slit type providing portions provide slit type areas and the outer viewing position correction comprises a widening of a number of slit type areas and an increasing the distance between the slit type areas the further towards the ends of the rows of the pixel group pairs from the centre of the rows.

45. A lens arrangement as claimed in any one of claims 32 to 44 wherein the series of pixel groups are arranged into a series of pixel group pairs; the pixel group pairs being spaced apart into rows and columns; each pixel group of a pixel group pair being in a row next to the other pixel group of the pixel group pair; each pixel group including a pixel having a number of colour sub-pixels; the colour sub-pixels being spaced apart along an associated one of the columns.

46. A lens arrangement as claimed in claim 45 wherein the slit type providing portions provide slit type areas the arrangement includes a chromatic aberration adjustment provided by slit type areas having different associated widths and spacings to align the maxima from differently coloured sub pixels.

47. A lens arrangement as claimed in any one of claims 32 to 55 wherein the series of pixel groups are arranged into a series of pixel group pairs; the pixel group pairs being spaced apart into rows and columns; each pixel group of a pixel group pair being in a row next to the other pixel group of the pixel group pair; each pixel group including a pixel having a number of colour sub-pixels; each sub pixel being provided in a row having chromatic aberration diffraction correction in the form of a predetermined slit with and spacing based on the colour of the sub pixel.

48. A lens arrangement as claimed in any one of claims 32 to 47 wherein the slit type portions providing portions and slit type portions are provided by a transmissive diffractive grating.

49. A lens arrangement as claimed in claim 48 wherein the slit type portions providing portions provide slit type areas having a number of concave grooves.

50. A lens arrangement as claimed in any one of claims 32 to 47 wherein the slit type portions providing areas and slit type portions are provided by a slit type diffractive grating.

51. A lens arrangement as claimed in claim 50 wherein the slit type portions providing portions provide slit type areas having a number of elongate slits.

52. A lens arrangement for an autostereoscopic display comprising: a number of light directing portions for receiving light from a series of pixel groups, each pixel group containing at least four pixels, the number of pixels being herein represented as N where N>=4, each pixel of a pixel group for use in forming a different view as part of the display, the pixel groups being able to provide N different views at any one time.

53. A lens arrangement as claimed in claim 51 wherein the light directing portions are able to direct light to an equal number of N sub-positions.

54. A lens arrangement as claimed in claim 52 or 53 wherein N positions are separated by a pupillary distance or an average pupillary distance to provide N- 1 viewing positions.

55. A lens arrangement as claimed in any one of claims 51 to 54 wherein the light directing portions comprise facet type portions that are each associated with a pixel of a pixel group on a one to one basis for directing light from the pixel group to the N sub-positions

56. A lens arrangement for an autostereoscopic display comprising: a number of light directing portions arranged in series for receiving light from a series of pixel groups, each pixel group containing at least five pixels, the number of pixels being herein represented as N where N>=5, each pixel of a pixel group for use in forming a different view as part of the display, the pixel groups being able to provide N different views at any one time.

57. A lens arrangement as claimed in claim 55 wherein each pixel is associated with at least one light directing portion and each light directing portion is associated with a single pixel.

58. A lens arrangement as claimed in claim 56 wherein the pixels in each pixel group are arranged in series; the first and last pixel in each series being associated with a single light directing portion and the other pixels being associated with two light directing portions.

59. A lens arrangement as claimed in claim 57 wherein the light directing portions are able to direct light to N-l viewing positions; each viewing position being associated with a pair of sub-positions to which light is directed by the light directing portions; the pair of sub-positions being separated by a pupillary type distance or an average pupillary distance.

60. A lens arrangement as claimed in claim 58 wherein each viewing position M is associated with a view M and a subsequent view M+l for M=l to N-l to provide autostereoscopy for a moving observer.

61. A lens arrangement as claimed in any one of claims 55 to 59 wherein the light directing portions each comprise a facet type portion.

62. A method of providing a number of viewing positions for a autostereoscopic image, the method comprising: projecting light from N sets of pixels, each set of pixels providing a different view of the stereoscopic image; and directing the light to 2(N-1) sub-positions to provide N-l viewing positions wherein each viewing position M is associated with a view M and a subsequent view M+l for M=l to N-l to provide autostereoscopy for a moving observer.

63. A lens arrangement for an autostereoscopic display comprising a series of viewing zone correction portions able to provide a number of views to different viewing zones associated with different viewing groups, the views being formed by directing light from a series of pixel groups.

64. A lens arrangement as claimed in claimed in claim 63 wherein the series of pixel groups are arranged into one or more rows and the viewing zone correction portions each comprise a series of viewing zone lenses associated with a row of the series of pixel groups.

65. A lens arrangement as claimed in claim 63 wherein the thickness of each series of viewing zone lenses comprises the thickness the corresponding row and each viewing zone lens of the series of viewing zone lenses is associated with a different viewing zone.

66. A lens arrangement as claimed in claim 64 wherein each viewing zone lens of each series of viewing zone lenses is associated with a viewing zone having a different viewing height.

67. A lens arrangement as claimed in any one of claims 62 to 65 wherein the series of viewing zone lens comprise series of viewing zone refractive type lenses.

68. A lens arrangement as claimed in claim 66 wherein the each viewing zone refractive type lens of the series of viewing zone lenses is associated with a viewing zone and is angled on its forward surface to direct the light to a viewing height associated with the viewing zone.

69. A lens arrangement as claimed in claim 66 or 67 wherein each viewing zone refractive type lens includes a number of facet type portions on its outward surface, facing the viewing zone, that are inset to provide a reduced thickness.

70. A lens arrangement as claimed in claim 66, 67 or 68 wherein each viewing zone refractive type lens includes a number of facet type portions on its inward surface, facing the pixel groups, the facet type portions being able to direct light from the series of pixel groups with increased widening from a top back viewing zone to a bottom front viewing zone.

71. A lens arrangement as claimed in claim 69 wherein the lens arrangement provides an autostereoscopic display for a cinema.

72. A lens arrangement as claimed in any one of claims 66 to 70 wherein each viewing zone refractive type lens has a refractive index gradient.

73. A lens arrangement as claimed in any one of claims 62 to 65 wherein the series of viewing zone lens comprise series of diffraction grating lenses having different spacing's and thicknesses.

74. A lens arrangement for an autostereoscopic display comprising: facet type portions that are inset to provide a reduced thickness, the facet type portions being arranged in series for forming stereoscopic images from a series of pixel group pairs wherein the facet type portions are angled to adopt a nonstandard concavity or convexity that is able to provide: (i) an angulating function for directing light from each pixel group in a pixel group pair to respective left and right visual fields; (ii) a viewing zone function for directing light from each pixel group to a number of different viewing zones each associated with different heights; and (iii) an aberration function for limiting colour aberration effects of colour sub pixels of the pixel groups.

75. A lens arrangement as claimed in claim 73 wherein the width of each facet type portion is less than 100 microns.

76. A lens arrangement as claimed in claim 73 or 74 wherein the width of each facet type portion between 20 and 80 microns. A lens arrangement as claimed in claim 73, 74 or 75 wherein the width of each facet type portion is about 50 microns.