EP3186962A1 - Improved resolution for autostereoscopic video displays - Google Patents

Improved resolution for autostereoscopic video displays

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Publication number
EP3186962A1
EP3186962A1 EP14795694.0A EP14795694A EP3186962A1 EP 3186962 A1 EP3186962 A1 EP 3186962A1 EP 14795694 A EP14795694 A EP 14795694A EP 3186962 A1 EP3186962 A1 EP 3186962A1
Authority
EP
European Patent Office
Prior art keywords
pixel
view
lenses
physical
pixels
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP14795694.0A
Other languages
German (de)
French (fr)
Inventor
Richard A. Muller
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Soliddd Corp
Original Assignee
Soliddd Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Soliddd Corp filed Critical Soliddd Corp
Publication of EP3186962A1 publication Critical patent/EP3186962A1/en
Withdrawn legal-status Critical Current

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Classifications

    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B30/00Optical systems or apparatus for producing three-dimensional [3D] effects, e.g. stereoscopic images
    • G02B30/20Optical systems or apparatus for producing three-dimensional [3D] effects, e.g. stereoscopic images by providing first and second parallax images to an observer's left and right eyes
    • G02B30/22Optical systems or apparatus for producing three-dimensional [3D] effects, e.g. stereoscopic images by providing first and second parallax images to an observer's left and right eyes of the stereoscopic type
    • G02B30/24Optical systems or apparatus for producing three-dimensional [3D] effects, e.g. stereoscopic images by providing first and second parallax images to an observer's left and right eyes of the stereoscopic type involving temporal multiplexing, e.g. using sequentially activated left and right shutters
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B30/00Optical systems or apparatus for producing three-dimensional [3D] effects, e.g. stereoscopic images
    • G02B30/20Optical systems or apparatus for producing three-dimensional [3D] effects, e.g. stereoscopic images by providing first and second parallax images to an observer's left and right eyes
    • G02B30/26Optical systems or apparatus for producing three-dimensional [3D] effects, e.g. stereoscopic images by providing first and second parallax images to an observer's left and right eyes of the autostereoscopic type
    • G02B30/27Optical systems or apparatus for producing three-dimensional [3D] effects, e.g. stereoscopic images by providing first and second parallax images to an observer's left and right eyes of the autostereoscopic type involving lenticular arrays
    • GPHYSICS
    • G02OPTICS
    • G02FOPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333Constructional arrangements; Manufacturing methods
    • G02F1/1335Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/133526Lenses, e.g. microlenses or Fresnel lenses
    • GPHYSICS
    • G02OPTICS
    • G02FOPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/29Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the position or the direction of light beams, i.e. deflection
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N13/00Stereoscopic video systems; Multi-view video systems; Details thereof
    • H04N13/30Image reproducers
    • H04N13/302Image reproducers for viewing without the aid of special glasses, i.e. using autostereoscopic displays
    • H04N13/305Image reproducers for viewing without the aid of special glasses, i.e. using autostereoscopic displays using lenticular lenses, e.g. arrangements of cylindrical lenses
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N13/00Stereoscopic video systems; Multi-view video systems; Details thereof
    • H04N13/30Image reproducers
    • H04N13/302Image reproducers for viewing without the aid of special glasses, i.e. using autostereoscopic displays
    • H04N13/31Image reproducers for viewing without the aid of special glasses, i.e. using autostereoscopic displays using parallax barriers
    • H04N13/315Image reproducers for viewing without the aid of special glasses, i.e. using autostereoscopic displays using parallax barriers the parallax barriers being time-variant
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N13/00Stereoscopic video systems; Multi-view video systems; Details thereof
    • H04N13/30Image reproducers
    • H04N13/349Multi-view displays for displaying three or more geometrical viewpoints without viewer tracking
    • H04N13/354Multi-view displays for displaying three or more geometrical viewpoints without viewer tracking for displaying sequentially
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B30/00Optical systems or apparatus for producing three-dimensional [3D] effects, e.g. stereoscopic images
    • G02B30/20Optical systems or apparatus for producing three-dimensional [3D] effects, e.g. stereoscopic images by providing first and second parallax images to an observer's left and right eyes
    • G02B30/26Optical systems or apparatus for producing three-dimensional [3D] effects, e.g. stereoscopic images by providing first and second parallax images to an observer's left and right eyes of the autostereoscopic type
    • G02B30/30Optical systems or apparatus for producing three-dimensional [3D] effects, e.g. stereoscopic images by providing first and second parallax images to an observer's left and right eyes of the autostereoscopic type involving parallax barriers

Definitions

  • the present invention relates generally to autostereoscopic displays, and, more particularly, to a video autostereoscopic display with significantly improved resolution.
  • Each eye of the viewer therefore sees an image whose horizontal resolution is halved in an autostereoscopic displays having only two views.
  • field of view is improved by having more than just two views.
  • many more views - e.g., 24 views - are required within a relatively narrow space - e.g., 1mm.
  • a typical LCD display screen has a pixel density of about 200 pixels per inch, though some have densities approaching 300 pixels per inch. That's approximately 6 pixels per millimeter, i.e., about one quarter of the resolution required to provide 24 views in a 1mm space.
  • a single pixel of a video display can display respective individual pixels of multiple views.
  • a video display can include more views for an autostereoscopic image than the physical pixels of the video display would ordinarily support.
  • the physical pixel is time-multiplexed.
  • the physical pixel displays a pixel of one view for a given time interval and a view multiplexer deflects the light from the physical pixel by a predetermined angle to make the pixel appear in a location corresponding to the pixel of the view.
  • the physical pixel displays a pixel of a different view and the view multiplexer deflects light from the physical pixel by a different predetermined angle to make the pixel appear in a location corresponding to the pixel of the different view.
  • the view multiplexer includes a number of columnar prisms of birefringent material such that deflection of light passing through the columnar prisms is switchable between two different angles by controlling the polarity of the light passing through.
  • the material of the columnar prisms varies its refraction index according to an electrical field of the columnar prisms.
  • An example of such a material is liquid crystal.
  • Multiple view multiplexers can be stacked to provide a wider variety of cumulative deflection angles.
  • Figure 1 is a plan view of a viewer and an autostereoscopic display in accordance with the present invention.
  • Figure 2 is a plan view of a portion of the autostereoscopic display of Figure 1 in greater detail.
  • Figure 3 is a plan view of a view multiplexer of the autostereoscopic display of Figures 1 and 2 in greater detail.
  • Figure 4 is a timing diagram illustrating the time-multiplexing of a pixel using two (2) view multiplexers in accordance with the present invention.
  • Figure 5 is a plan view of an alternative autostereoscopic display in accordance with the present invention.
  • Figure 6 is a plan view of a portion of the autostereoscopic display of Figure 5 in greater detail.
  • Figure 7 is a plan view illustrating focus of the autostereoscopic display of Figures 5 and 6.
  • Figure 8 is a plan view of an alternative view multiplexer in accordance with the present invention.
  • Figures 9 and 10 are timing diagrams illustrating time-multiplexing of a pixel using the view multiplexer of Figure 8.
  • Figure 11 is a plan view of the mask of Figure 2 enlarged to illustrate locations of apparent pixels due to operation of view multiplexers of Figure 2.
  • a single pixel of a video display can display respective individual pixels of multiple views.
  • a stereoscopic display 100 ( Figures 1 and 2) includes view multiplexers 204A-B ( Figure 2) that bend light from each of a number of pixels, such as pixels 216A-F, such that each pixel appears to be at a slightly different location and represents a pixel of a different view for each of a number of multiple time intervals.
  • view multiplexers 204A-B can cause pixel 216A to be at any of locations 216A1 ( Figure 11), 216A2, 216A3, and 216A4.
  • each of pixels 216A-F is time- multiplexed to represent pixels of respective multiple views of an autostereoscopic display.
  • view multiplexers 204 A-B combine to provide 4-to-l multiplexing in this illustrative embodiment.
  • View multiplexers 204A-B bend light from pixels 216A-F at predetermined, fractional view angles at predetermined time intervals.
  • lenticle 202C is designed to provide a view angle increment of one degree, meaning that viewing perspectives through lenticle 202C at which each of pixels 216A-F is viewable through a mask 214 differ by one degree.
  • view multiplexers 204A-B combine to deflect light at four (4), evenly spaced, fractional view angles, namely, 0 degrees, 0.25 degrees, 0.5 degrees, and 0.75 degrees in this illustrative embodiment; other angles can be used in other embodiments.
  • a single view multiplexer can provide two (2) views from a single pixel, three (3) view multiplexers can be combined to provide up to eight (8) views from a single pixel, and numerous other combinations can be implemented to provide even more views from a single pixel. It should be further appreciated that a view multiplexer can sweep across a range of deflection angles to provide other numbers of views from a single pixel in the manner described below.
  • FIG. 400 Display of four (4) views using a single one of pixels 216A-F is shown in timing diagram 400 ( Figure 4).
  • view multiplexer 204A is switchable between deflecting light at 0.5 degrees or not deflecting light at all
  • view multiplexer 204B is switchable between deflecting light at 0.25 degrees or not deflecting light at all.
  • View multiplexers 204A-B switch at a rate of 120Hz
  • view multiplexer 204B follows view multiplexer 204 As by a lag of one-half clock cycle as shown in timing diagram 400.
  • Pixels 216A-F have a refresh rate of 240Hz.
  • view multiplexers 204A-B are both off, i.e., not deflecting light, and pixel 216A displays a pixel of view N for a single refresh cycle. If an eye of viewer 10 is aligned with pixel 216A through mask 214 and lenticle 202 A, that eye will see view N of pixel 216A at location 216A1 ( Figure 11) and the pixel of view N will appear to occupy the entire width of lenticle 202A ( Figure 2).
  • the deflection of view multiplexers 204A-B cause the eye to see flat black mask 214.
  • the persistence of vision causes viewer 10 to continue to see the pixel of view N at location 216A1 ( Figure 11) for four (4) 240Hz cycles.
  • view multiplexer 204A switches on.
  • the cumulative deflection of view multiplexers 204A-B is 0.5 degrees, and pixel 216A appears to be at location 216A3 ( Figure 11) and displays a pixel of view N+2 ( Figure 4) for a single refresh cycle. If an eye of viewer 10 is 0.5 degrees from being aligned with pixel 216A through mask 214 and lenticle 202 A, that eye will see view N+2 of pixel 216A and the pixel of view N+2 will appear to occupy the entire width of lenticle 202 A.
  • Mask 214 and the persistence of vision cause viewer 10 to continue to see the pixel of view N+2 at location 216A3 ( Figure 11) for four (4) 240Hz cycles as described above.
  • view multiplexer 204B switches on.
  • the cumulative deflection of view multiplexers 204A-B is 0.75 degrees, and pixel 216A appears to be at location 216A4 ( Figure 11) and displays a pixel of view N+3 ( Figure 4) for a single refresh cycle. If an eye of viewer 10 is 0.75 degrees from being aligned with pixel 216A through mask 214 and lenticle 202 A, that eye will see view N+3 of pixel 216A and the pixel of view N+3 will appear to occupy the entire width of lenticle 202 A.
  • Mask 214 and the persistence of vision cause viewer 10 to continue to see the pixel of view N+3 at location 216A4 ( Figure 11) for four (4) 240Hz cycles as described above.
  • view multiplexer 204A switches off.
  • the cumulative deflection of view multiplexers 204A-B is 0.25 degrees, and pixel 216A appears to be at location 216A2 ( Figure 11) and displays a pixel of view N+l ( Figure 4) for a single refresh cycle. If an eye of viewer 10 is 0.25 degrees from being aligned with pixel 216A through mask 214 and lenticle 202 A, that eye will see view N+l of pixel 216A and the pixel of view N+l will appear to occupy the entire width of lenticle 202 A.
  • Mask 214 and the persistence of vision cause viewer 10 to continue to see the pixel of view N+l at location 216A2 ( Figure 11) for four (4) 240Hz cycles as described above.
  • view multiplexer 204B switches off.
  • the cumulative deflection of view multiplexers 204A-B is 0 degrees, and pixel 216A again displays a pixel of view N and appears to be at location 216A1 ( Figure 11) for a single refresh cycle.
  • the four (4) cycle pattern of timing diagram 400 ( Figure 4) repeats.
  • view multiplexers 204A-B time-multiplex pixels 216A-F such that each pixel can display a pixel of four (4) different views of autostereoscopic display 100. It should be appreciated that, without lenticles 202A-C, pixel 216A would appear to a human viewer to be four (4) distinct pixels at locations 216A1 ( Figure 11), 216A2, 216A3, and 216A4. Thus, without a lenticular array or other view selector, view multiplexers 204A-B cause a display to have an apparent resolution that is much more dense than the physical resolution of the display.
  • a parallax barrier can be used.
  • using lasers rather than LCDs or LEDs as light sources allow the individual views displayed by a particular pixel to be only visible at locations to which the laser's light is directed.
  • autostereoscopic display 100 includes a number of lenticles 202A-C of a lenticular array.
  • lenticles 202A-C are designed to provide a relatively fiat field in the manner described in copending U.S. Patent Application 12/901,478 for "Improved Perceived Image Depth for Autostereoscopic Displays" by Dr. Richard A. Muller on October 8, 2010.
  • Other approaches to minimize lenticle focus errors due to curvature of fields are described below.
  • View multiplexers 204 A-B are immediately behind the lenticular array in this illustrative embodiment. View multiplexers 204A-B are described in more detail below in conjunction with Figure 3. Behind view multiplexers 204A-B is a layer 206 of transparent material such as plastic, glass, or a gas such as air, a polarizer 208, and a second layer 210 of transparent material.
  • Behind layer 210 is an array of color filters 212A-F, each of which imparts a red, green, or blue hue to a respective one of pixels 216A-F.
  • Pixels 216A-F are vertical pixels as described in co-pending U.S. Patent Application 12/868,038 for "Improved Resolution for Autostereoscopic Video Displays" by Dr. Richard A.
  • Mask 214 is positioned between color filters 212A-F and pixels 216A- F and limits the perceived width of pixels 216A-F to about one-quarter their actual width, leaving dark space between pixels 216A-F for apparent pixels due to light deflection by operation of view multiplexers 204 A-B.
  • the field of focus of lenticles 202 A-C is at about mask 214.
  • Pixels 216A-F are positioned immediately behind mask 214.
  • Each of pixels 216A-F is a single, independently controlled LCD sub-pixel, having its own independently controlled display intensity. The color of each of pixels 216A-F is controlled by a respective one of color filters 212A-F.
  • Behind pixels 216A-F is another layer 218 of transparent material and a polarizer 220.
  • Behind polarizer 220 is a light source (not shown) as is typical in conventional LCD displays.
  • Polarizers 208 and 220 are similar to polarizers used in conventional LCD displays.
  • View multiplexer 204A is shown in greater detail in Figure 3. Except as otherwise noted herein, view multiplexer 204B is directly analogous to view multiplexer 204A and the following description is also applicable to view multiplexer 204B.
  • View multiplexer 204A ( Figure 3) is shown in cross-section view from above and includes triangular columns 304A-C of birefringent material such as liquid crystal. Triangular columns 304A-C are positioned between a layer 302 of transparent plastic or glass and a grooved layer 306 of transparent plastic or glass into which triangular grooves are made to provide space for triangular columns 304A-C.
  • Behind layer 306 is a switch layer 310 of liquid crystal between electrode layers 308 and 312.
  • polarization of light passing through switch layer 310 can be switched, e.g., between parallel and perpendicular orientations relative to the birefringent material in triangular columns 304A-C.
  • the birefringent material, its orientation set at manufacture, and the size and shape of triangular columns 304A-C are selected to provide one amount of light deflection with one polarization orientation of switch layer 310 and a different amount of deflection with the other polarization orientation of switch layer 310.
  • the birefringent material in triangular columns 304A-C are prisms whose degree of light deflection vary according to the state of switch layer 310.
  • the birefringent material is selected to have one refraction index substantially equal to the refraction index of the transparent material of layers 302 and 306, and therefore provides no deflection of light as shown by arrow 314 A, for one polarization orientation of switch layer 310.
  • the prisms of triangular columns 304A-C disappear into layers 302 and 306, and triangular columns 304A-C and layers 302 and 306 appear to be a single, flat layer of transparent material.
  • pixel 216A can be made to appear in one of at least two different, perhaps overlapping, locations and thus serve the purpose of time- multiplexing of pixel 216A.
  • the birefringent material, its orientation set at manufacture, and the size and shape of triangular columns 304A-C in view multiplexer 204 A are selected to deflect light by 0.5 degrees as shown by arrow 314B, and the birefringent material, its orientation set at manufacture, and the size and shape of triangular columns 304A-C in view multiplexer 204B are selected to deflect light by 0.25 degrees.
  • the different refraction index of the birefringent material with this polarization orientation and the dimensions of triangular columns 304A-C are prisms designed to reflect light by a predetermined desired angle, such as 0.5 degrees in view multiplexer 204A and 0.25 degrees in view multiplexer 204B in this illustrative embodiment.
  • autostereoscopic display 100 includes a number of lenticles 202A-C that are designed to provide a relatively flat field in the manner described in the '478 Application.
  • Another approach to reducing autostereoscopic image degradation due to curvature of field of conventional lenticles is illustrated by Figures 5 and 6.
  • Viewers 10 are viewing an autostereoscopic image displayed by autostereoscopic display 100B from various viewing angles.
  • Autostereoscopic display 100B is an alternative embodiment to that of
  • Autostereoscopic display 100 and is directly analogous to autostereoscopic display 100 except as otherwise described herein.
  • Autostereoscopic display 100B does not include meniscus-cylinder lenticles but instead includes lenticles of a more conventional design, having a convex proximal surface and a flat distal surface.
  • An autostereoscopic image is best viewed in very good focus.
  • the focus target is mask 214B.
  • viewing angles that stray significantly from directly perpendicular to autostereoscopic display 100B tend to be out of focus due to the curvature of field of some lenticles.
  • This curvature of field is illustrated by curved line 502, which represents the locus of foci of the lenticle at various angles of perspective.
  • the lenticular array of autostereo scopic display 100B are focused slightly behind mask 214B to provide loci of focus along curved line 504.
  • Curved line 502 represents loci of focus provided by a lenticle in a typical conventional autostereoscopic display. Curved line 502 shows a very good focus, i.e., near zero focus error, for straight-on viewing angles, i.e., perpendicular to autostereoscopic display 100B. At a wider viewing angles, curved line 502 shows a noticeable focus error 602.
  • lenticles of autostereoscopic display 100B are designed to focus behind mask 214B for straight-on viewing angles.
  • curved line 504 is behind mask 214B by an amount that, from viewing perspectives near perpendicular to mask 214, the focus of lenticles of autostereoscopic display 100B are blurred by a width 702 that is no more than the width of the gaps in mask 214B.
  • Such limited blurring does not affect the accuracy of the autostereoscopic image perceived by viewer 10 because nothing other than the intended pixel is viewable to viewer 10 through each lenticle.
  • the focus error 604 ( Figure 6) viewable at near perpendicular viewing angles is sufficiently small to not affect the perception of focus of viewer 10.
  • curved line 504 intersects mask 214B to provide very good focus, yet no better than that perceivable by viewer 10 at near perpendicular viewing angles, and begins to blur at even wider viewing perspectives as curved line 504 is in front of mask 214B.
  • the quality of view as perceived by viewer 10 is preserved at these wider viewing perspectives up to a focus error 606, beyond which the amount of blurring exceeds the width of gaps in mask 214B.
  • maintaining focus errors no wider than gaps in mask 214B might allow for unacceptably large focus errors at wider angles of viewing perspective.
  • best results are achieved by determining the width of blur over a range of viewing angles for which quality viewing is desired and selecting a lens and locus of foci whose width of blur is minimized over that range of viewing angles.
  • the result is that lenticles whose locus of foci are represented by curved line 504 provide a much wider range of acceptable viewing angles than do conventional lenticles.
  • a single view multiplexer 804 (shown in cross section view in Figure 8) can sweep across a range of deflection angles to provide a number of views from a single pixel.
  • View multiplexer 804 includes triangular columns 808A-C of a material whose refraction index is controllable, e.g., by an electrical field.
  • a material whose refraction index is controllable, e.g., by an electrical field.
  • An example of such a material is liquid crystal.
  • Triangular columns 808A-C are positioned between a layer 606 of transparent plastic or glass and a grooved layer 810 of transparent plastic or glass into which triangular grooves are made to provide space for triangular columns 808 A-C.
  • Electrode layer 802. Behind layer 810 is an electrode layer 812.
  • the refraction index of the material in triangular columns 808A-C can be varied.
  • triangular columns 808A-C The material within triangular columns 808A-C, its orientation set at manufacture, and the size and shape of triangular columns 808A-C are selected to provide a desired range of deflection across the range of electrical fields that can be produced across electrode layers 802 and 812.
  • the material in triangular columns 808A-C are prisms whose degree of light defiection vary according to the electrical field between electrode layers 802 and 812.
  • the desired range of deflection is 0.0- 2.0 degrees
  • the material within triangular columns 808A-C has a refraction index that varies from the refraction index of layers 806 and 810 to 0.1 above the refraction index of layers 806 and 810
  • triangular columns 808 A-C have a cross-sections that are right triangles with an angle 816 of 20 degrees.
  • Timing diagram 900 ( Figure 9) illustrates the time-multiplexing of pixel 216A using view multiplexer 804.
  • Timing diagram 900 shows an electrical field between electrode layers 802 and 812, the corresponding angle of deflection of view multiplexer 804, and various views displayed by pixel 216A.
  • the angle of deflection provided by view multiplexer 804 sweeps through a predetermined range, e.g., 0-2.0 degrees.
  • Pixel 216A displays pixels of views N through N+3 in a synchronized manner such that pixel 216A displays a pixel of view N while view multiplexer 804 sweeps through deflection angles 0.0-0.5 degrees, displays a pixel of view N+l while view multiplexer 804 sweeps through deflection angles 0.5-1.0 degrees, displays a pixel of view N+2 while view multiplexer 804 sweeps through defiection angles 1.0- 1.5 degrees, and displays a pixel of view N+3 while view multiplexer 804 sweeps through deflection angles 1.5-2.0 degrees, after which view multiplexer 804 returns to provide a deflection of 0 degrees and pixel 216A displays a pixel of the next frame of view N.
  • pixel 216A is shown to time- mulitplex only four (4) views, pixel 216A can time-multiplex many more views, limited only by the switching rate of pixel 216A relative to a desired frame rate.
  • pixel 216A is implemented using one or more LEDs, e.g., in very large signage, pixel 216A can switch much more rapidly than an LCD pixel and can time -multiplex many more views. For example, some LEDs can switch at frequencies of 2.0MHz.
  • a single LED (or a cluster of red, green, and blue LEDs) can provide 300 or more views of single pixel, limited only by the optical quality of lenticles 202A-C and the range of deflection angles and switching speed of view multiplexer 804.
  • Timing diagram 1000 shows an alternative manner in which view multiplexer 804 can time-multiplex pixels of multiple views shown by pixel 216A.
  • view multiplexer 804 sweeps through a range of deflection angles, e.g., 0-2.0 degrees
  • view multiplexer 804 sweeps back through the range in reverse direction, e.g., from 2.0 degrees to 0 degrees.
  • pixel 216A switches through pixels of views N, N+1, N+2, and N+3
  • pixel 216A switches through pixels of a subsequent frame in reverse order, i.e., through views N+3, N+2, N+1, and N.
  • view multiplexer 804 can cycle through angles of deflection in other ways, including stepped patterns.
  • multiple instances of view multiplexer 804 can be stacked as are view multiplexers 204A-B ( Figure 2) to provide greater ranges of cumulative defiection angles.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Nonlinear Science (AREA)
  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Mathematical Physics (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Testing, Inspecting, Measuring Of Stereoscopic Televisions And Televisions (AREA)

Abstract

A single pixel of a video display can display respective individual pixels of multiple views. In other words, a video display can include more views for an autostereoscopic image than the physical pixels of the video display would ordinarily support. The physical pixel is time-multiplexed in that the physical pixel displays a pixel of one view for a given time interval and a view multiplexer deflects the light from the physical pixel by a predetermined angle to make the pixel appear in a location corresponding to the pixel of the view. In another time interval, the physical pixel displays a pixel of a different view and the view multiplexer deflects light from the physical pixel by a different predetermined angle to make the pixel appear in a location corresponding to the pixel of the different view.

Description

IMPROVED RESOLUTION FOR AUTOSTEREOSCOPIC VIDEO DISPLAYS FIELD
[0001] The present invention relates generally to autostereoscopic displays, and, more particularly, to a video autostereoscopic display with significantly improved resolution.
BACKGROUND
[0002] Conventional autostereoscopic displays use arrays of lenses or parallax barriers or other view selectors to make a number of pixels of the display visible to one eye of a viewing person and to make a number of other pixels of the display visible to the other eye of the viewing person. By isolating the pixels of the display visible to each eye, the two components of a stereoscopic image can be presented on the display.
[0003] Since an ordinary viewer's eyes are side-by-side and aligned horizontally, the array of lenses makes pixels visible according to horizontal orientation. As a result, corresponding pixels for the left and right eyes are located in the same scanline and displaced from one another horizontally.
[0004] Each eye of the viewer therefore sees an image whose horizontal resolution is halved in an autostereoscopic displays having only two views. In most autostereoscopic displays, field of view is improved by having more than just two views. In attempts to provide greater perceived depths of projection, many more views - e.g., 24 views - are required within a relatively narrow space - e.g., 1mm. A typical LCD display screen has a pixel density of about 200 pixels per inch, though some have densities approaching 300 pixels per inch. That's approximately 6 pixels per millimeter, i.e., about one quarter of the resolution required to provide 24 views in a 1mm space.
[0005] Thus, conventional video display devices are incapable of providing enough views in a sufficiently small space to satisfy the demands of modern autostereoscopic images.
BRIEF SUMMARY
[0006] In accordance with the present invention, a single pixel of a video display can display respective individual pixels of multiple views. In other words, a video display can include more views for an autostereoscopic image than the physical pixels of the video display would ordinarily support.
[0007] To achieve multiple views with a single physical pixel, the physical pixel is time-multiplexed. In particular, the physical pixel displays a pixel of one view for a given time interval and a view multiplexer deflects the light from the physical pixel by a predetermined angle to make the pixel appear in a location corresponding to the pixel of the view. In another time interval, the physical pixel displays a pixel of a different view and the view multiplexer deflects light from the physical pixel by a different predetermined angle to make the pixel appear in a location corresponding to the pixel of the different view.
[0008] The view multiplexer includes a number of columnar prisms of birefringent material such that deflection of light passing through the columnar prisms is switchable between two different angles by controlling the polarity of the light passing through. Alternatively, the material of the columnar prisms varies its refraction index according to an electrical field of the columnar prisms. An example of such a material is liquid crystal. The controllability of the reflection angles provided by the columnar prisms enables control of the location at which a given pixel appears to be to a human viewer.
[0009] By synchronizing the location at which a given pixel appears to be and the particular view displayed by the pixel allows that pixel to display pixels of multiple views for respective fractions of a frame rate. Persistence of vision of the human viewer causes the one pixel of the one view that is visible to the viewer through the lenticular array to continue to be perceived for the entire frame.
[0010] Multiple view multiplexers can be stacked to provide a wider variety of cumulative deflection angles.
[0011] In addition, focus errors due to curvature of field of the individual lenticles of a lenticular array are reduced by configuring the lenticles to focus at an acceptable distance behind the target of focus, e.g., the pixels of the autostereoscopic display. The result is that, due to curvature of field, the lenticles will focus particularly well at moderate angles of viewing perspective and will still produce acceptable focus errors and even wider angles of viewing perspective.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0012] Figure 1 is a plan view of a viewer and an autostereoscopic display in accordance with the present invention.
[0013] Figure 2 is a plan view of a portion of the autostereoscopic display of Figure 1 in greater detail.
[0014] Figure 3 is a plan view of a view multiplexer of the autostereoscopic display of Figures 1 and 2 in greater detail.
[0015] Figure 4 is a timing diagram illustrating the time-multiplexing of a pixel using two (2) view multiplexers in accordance with the present invention.
[0016] Figure 5 is a plan view of an alternative autostereoscopic display in accordance with the present invention.
[0017] Figure 6 is a plan view of a portion of the autostereoscopic display of Figure 5 in greater detail.
[0018] Figure 7 is a plan view illustrating focus of the autostereoscopic display of Figures 5 and 6. [0019] Figure 8 is a plan view of an alternative view multiplexer in accordance with the present invention.
[0020] Figures 9 and 10 are timing diagrams illustrating time-multiplexing of a pixel using the view multiplexer of Figure 8.
[0021] Figure 11 is a plan view of the mask of Figure 2 enlarged to illustrate locations of apparent pixels due to operation of view multiplexers of Figure 2.
DETAILED DESCRIPTION
[0022] In accordance with the present invention, a single pixel of a video display can display respective individual pixels of multiple views. In particular, a stereoscopic display 100 (Figures 1 and 2) includes view multiplexers 204A-B (Figure 2) that bend light from each of a number of pixels, such as pixels 216A-F, such that each pixel appears to be at a slightly different location and represents a pixel of a different view for each of a number of multiple time intervals. For example, view multiplexers 204A-B can cause pixel 216A to be at any of locations 216A1 (Figure 11), 216A2, 216A3, and 216A4. In this manner, each of pixels 216A-F is time- multiplexed to represent pixels of respective multiple views of an autostereoscopic display.
[0023] In a manner described more completely below, view multiplexers 204 A-B combine to provide 4-to-l multiplexing in this illustrative embodiment. View multiplexers 204A-B bend light from pixels 216A-F at predetermined, fractional view angles at predetermined time intervals. In this illustrative
embodiment, lenticle 202C is designed to provide a view angle increment of one degree, meaning that viewing perspectives through lenticle 202C at which each of pixels 216A-F is viewable through a mask 214 differ by one degree. To provide four (4) views from a single pixel, view multiplexers 204A-B combine to deflect light at four (4), evenly spaced, fractional view angles, namely, 0 degrees, 0.25 degrees, 0.5 degrees, and 0.75 degrees in this illustrative embodiment; other angles can be used in other embodiments. It should be appreciated that a single view multiplexer can provide two (2) views from a single pixel, three (3) view multiplexers can be combined to provide up to eight (8) views from a single pixel, and numerous other combinations can be implemented to provide even more views from a single pixel. It should be further appreciated that a view multiplexer can sweep across a range of deflection angles to provide other numbers of views from a single pixel in the manner described below.
[0024] Display of four (4) views using a single one of pixels 216A-F is shown in timing diagram 400 (Figure 4). As described more completely below, view multiplexer 204A is switchable between deflecting light at 0.5 degrees or not deflecting light at all, and view multiplexer 204B is switchable between deflecting light at 0.25 degrees or not deflecting light at all. View multiplexers 204A-B switch at a rate of 120Hz, and view multiplexer 204B follows view multiplexer 204 As by a lag of one-half clock cycle as shown in timing diagram 400.
[0025] Pixels 216A-F have a refresh rate of 240Hz. Initially in timing diagram 400, view multiplexers 204A-B are both off, i.e., not deflecting light, and pixel 216A displays a pixel of view N for a single refresh cycle. If an eye of viewer 10 is aligned with pixel 216A through mask 214 and lenticle 202 A, that eye will see view N of pixel 216A at location 216A1 (Figure 11) and the pixel of view N will appear to occupy the entire width of lenticle 202A (Figure 2). When pixel 216A is displaying pixels of other views, the deflection of view multiplexers 204A-B cause the eye to see flat black mask 214. However, the persistence of vision causes viewer 10 to continue to see the pixel of view N at location 216A1 (Figure 11) for four (4) 240Hz cycles.
[0026] In the next 240Hz cycle (Figure 4), view multiplexer 204A switches on. The cumulative deflection of view multiplexers 204A-B is 0.5 degrees, and pixel 216A appears to be at location 216A3 (Figure 11) and displays a pixel of view N+2 (Figure 4) for a single refresh cycle. If an eye of viewer 10 is 0.5 degrees from being aligned with pixel 216A through mask 214 and lenticle 202 A, that eye will see view N+2 of pixel 216A and the pixel of view N+2 will appear to occupy the entire width of lenticle 202 A. Mask 214 and the persistence of vision cause viewer 10 to continue to see the pixel of view N+2 at location 216A3 (Figure 11) for four (4) 240Hz cycles as described above.
[0027] In the next 240Hz cycle (Figure 4), view multiplexer 204B switches on. The cumulative deflection of view multiplexers 204A-B is 0.75 degrees, and pixel 216A appears to be at location 216A4 (Figure 11) and displays a pixel of view N+3 (Figure 4) for a single refresh cycle. If an eye of viewer 10 is 0.75 degrees from being aligned with pixel 216A through mask 214 and lenticle 202 A, that eye will see view N+3 of pixel 216A and the pixel of view N+3 will appear to occupy the entire width of lenticle 202 A. Mask 214 and the persistence of vision cause viewer 10 to continue to see the pixel of view N+3 at location 216A4 (Figure 11) for four (4) 240Hz cycles as described above.
[0028] In the next 240Hz cycle (Figure 4), view multiplexer 204A switches off. The cumulative deflection of view multiplexers 204A-B is 0.25 degrees, and pixel 216A appears to be at location 216A2 (Figure 11) and displays a pixel of view N+l (Figure 4) for a single refresh cycle. If an eye of viewer 10 is 0.25 degrees from being aligned with pixel 216A through mask 214 and lenticle 202 A, that eye will see view N+l of pixel 216A and the pixel of view N+l will appear to occupy the entire width of lenticle 202 A. Mask 214 and the persistence of vision cause viewer 10 to continue to see the pixel of view N+l at location 216A2 (Figure 11) for four (4) 240Hz cycles as described above. [0029] In the next 240Hz cycle (Figure 4), view multiplexer 204B switches off. The cumulative deflection of view multiplexers 204A-B is 0 degrees, and pixel 216A again displays a pixel of view N and appears to be at location 216A1 (Figure 11) for a single refresh cycle. And, the four (4) cycle pattern of timing diagram 400 (Figure 4) repeats.
[0030] Thus, view multiplexers 204A-B time-multiplex pixels 216A-F such that each pixel can display a pixel of four (4) different views of autostereoscopic display 100. It should be appreciated that, without lenticles 202A-C, pixel 216A would appear to a human viewer to be four (4) distinct pixels at locations 216A1 (Figure 11), 216A2, 216A3, and 216A4. Thus, without a lenticular array or other view selector, view multiplexers 204A-B cause a display to have an apparent resolution that is much more dense than the physical resolution of the display.
[0031] It should also be appreciated that there are alternatives to a lenticular array to ensure that a human viewer sees only one of the multiple views of an autostereoscopic image. For example, a parallax barrier can be used. In addition, using lasers rather than LCDs or LEDs as light sources allow the individual views displayed by a particular pixel to be only visible at locations to which the laser's light is directed.
[0032] As shown in Figure 2, autostereoscopic display 100 includes a number of lenticles 202A-C of a lenticular array. In this illustrative embodiment, lenticles 202A-C are designed to provide a relatively fiat field in the manner described in copending U.S. Patent Application 12/901,478 for "Improved Perceived Image Depth for Autostereoscopic Displays" by Dr. Richard A. Muller on October 8, 2010. Other approaches to minimize lenticle focus errors due to curvature of fields are described below.
[0033] View multiplexers 204 A-B are immediately behind the lenticular array in this illustrative embodiment. View multiplexers 204A-B are described in more detail below in conjunction with Figure 3. Behind view multiplexers 204A-B is a layer 206 of transparent material such as plastic, glass, or a gas such as air, a polarizer 208, and a second layer 210 of transparent material.
[0034] Behind layer 210 is an array of color filters 212A-F, each of which imparts a red, green, or blue hue to a respective one of pixels 216A-F. Pixels 216A-F are vertical pixels as described in co-pending U.S. Patent Application 12/868,038 for "Improved Resolution for Autostereoscopic Video Displays" by Dr. Richard A.
Muller and filed August 25, 2010.
[0035] Mask 214 is positioned between color filters 212A-F and pixels 216A- F and limits the perceived width of pixels 216A-F to about one-quarter their actual width, leaving dark space between pixels 216A-F for apparent pixels due to light deflection by operation of view multiplexers 204 A-B. In this illustrative embodiment, the field of focus of lenticles 202 A-C is at about mask 214. [0036] Pixels 216A-F are positioned immediately behind mask 214. Each of pixels 216A-F is a single, independently controlled LCD sub-pixel, having its own independently controlled display intensity. The color of each of pixels 216A-F is controlled by a respective one of color filters 212A-F. Behind pixels 216A-F is another layer 218 of transparent material and a polarizer 220. Behind polarizer 220 is a light source (not shown) as is typical in conventional LCD displays. Polarizers 208 and 220 are similar to polarizers used in conventional LCD displays.
[0037] View multiplexer 204A is shown in greater detail in Figure 3. Except as otherwise noted herein, view multiplexer 204B is directly analogous to view multiplexer 204A and the following description is also applicable to view multiplexer 204B.
[0038] View multiplexer 204A (Figure 3) is shown in cross-section view from above and includes triangular columns 304A-C of birefringent material such as liquid crystal. Triangular columns 304A-C are positioned between a layer 302 of transparent plastic or glass and a grooved layer 306 of transparent plastic or glass into which triangular grooves are made to provide space for triangular columns 304A-C.
[0039] Behind layer 306 is a switch layer 310 of liquid crystal between electrode layers 308 and 312. By selectively applying a charge to electrode layers 308 and 312, polarization of light passing through switch layer 310 can be switched, e.g., between parallel and perpendicular orientations relative to the birefringent material in triangular columns 304A-C.
[0040] The birefringent material, its orientation set at manufacture, and the size and shape of triangular columns 304A-C are selected to provide one amount of light deflection with one polarization orientation of switch layer 310 and a different amount of deflection with the other polarization orientation of switch layer 310. In effect, the birefringent material in triangular columns 304A-C are prisms whose degree of light deflection vary according to the state of switch layer 310.
[0041] In this illustrative embodiment, the birefringent material is selected to have one refraction index substantially equal to the refraction index of the transparent material of layers 302 and 306, and therefore provides no deflection of light as shown by arrow 314 A, for one polarization orientation of switch layer 310. In effect, the prisms of triangular columns 304A-C disappear into layers 302 and 306, and triangular columns 304A-C and layers 302 and 306 appear to be a single, flat layer of transparent material. However, it should be appreciated that it is not necessary that the prisms provide a deflection of zero degrees to effectively disappear into layers 302 and 306. As long as the prisms are controllable to provide one of at least two different angles of deflection, pixel 216A can be made to appear in one of at least two different, perhaps overlapping, locations and thus serve the purpose of time- multiplexing of pixel 216A. [0042] For the other polarization orientation of switch layer 310 in this illustrative embodiment, the birefringent material, its orientation set at manufacture, and the size and shape of triangular columns 304A-C in view multiplexer 204 A are selected to deflect light by 0.5 degrees as shown by arrow 314B, and the birefringent material, its orientation set at manufacture, and the size and shape of triangular columns 304A-C in view multiplexer 204B are selected to deflect light by 0.25 degrees. In effect, the different refraction index of the birefringent material with this polarization orientation and the dimensions of triangular columns 304A-C are prisms designed to reflect light by a predetermined desired angle, such as 0.5 degrees in view multiplexer 204A and 0.25 degrees in view multiplexer 204B in this illustrative embodiment.
[0043] As described above, autostereoscopic display 100 includes a number of lenticles 202A-C that are designed to provide a relatively flat field in the manner described in the '478 Application. Another approach to reducing autostereoscopic image degradation due to curvature of field of conventional lenticles is illustrated by Figures 5 and 6.
[0044] Viewers 10 (Figure 5) are viewing an autostereoscopic image displayed by autostereoscopic display 100B from various viewing angles.
Autostereoscopic display 100B is an alternative embodiment to that of
autostereoscopic display 100 and is directly analogous to autostereoscopic display 100 except as otherwise described herein. Autostereoscopic display 100B does not include meniscus-cylinder lenticles but instead includes lenticles of a more conventional design, having a convex proximal surface and a flat distal surface.
[0045] An autostereoscopic image is best viewed in very good focus. In the case of autostereoscopic display 100B, the focus target is mask 214B. However, viewing angles that stray significantly from directly perpendicular to autostereoscopic display 100B tend to be out of focus due to the curvature of field of some lenticles. This curvature of field is illustrated by curved line 502, which represents the locus of foci of the lenticle at various angles of perspective. To reduce loss of focus over a wider range of viewing angles, the lenticular array of autostereo scopic display 100B are focused slightly behind mask 214B to provide loci of focus along curved line 504.
[0046] A portion of autostereoscopic display 100B is enlarged in Figure 6. Curved lines 502 and 504 are exaggerated to illustrate the focus errors therein.
[0047] Curved line 502 represents loci of focus provided by a lenticle in a typical conventional autostereoscopic display. Curved line 502 shows a very good focus, i.e., near zero focus error, for straight-on viewing angles, i.e., perpendicular to autostereoscopic display 100B. At a wider viewing angles, curved line 502 shows a noticeable focus error 602.
[0048] In this illustrative embodiment, lenticles of autostereoscopic display 100B are designed to focus behind mask 214B for straight-on viewing angles. As shown in Figure 7, curved line 504 is behind mask 214B by an amount that, from viewing perspectives near perpendicular to mask 214, the focus of lenticles of autostereoscopic display 100B are blurred by a width 702 that is no more than the width of the gaps in mask 214B. Such limited blurring does not affect the accuracy of the autostereoscopic image perceived by viewer 10 because nothing other than the intended pixel is viewable to viewer 10 through each lenticle. Thus, the focus error 604 (Figure 6) viewable at near perpendicular viewing angles is sufficiently small to not affect the perception of focus of viewer 10.
[0049] At wider viewing perspectives, curved line 504 intersects mask 214B to provide very good focus, yet no better than that perceivable by viewer 10 at near perpendicular viewing angles, and begins to blur at even wider viewing perspectives as curved line 504 is in front of mask 214B. The quality of view as perceived by viewer 10 is preserved at these wider viewing perspectives up to a focus error 606, beyond which the amount of blurring exceeds the width of gaps in mask 214B.
[0050] In some embodiments, maintaining focus errors no wider than gaps in mask 214B might allow for unacceptably large focus errors at wider angles of viewing perspective. Generally, best results are achieved by determining the width of blur over a range of viewing angles for which quality viewing is desired and selecting a lens and locus of foci whose width of blur is minimized over that range of viewing angles. [0051] The result is that lenticles whose locus of foci are represented by curved line 504 provide a much wider range of acceptable viewing angles than do conventional lenticles.
[0052] As described briefly above, a single view multiplexer 804 (shown in cross section view in Figure 8) can sweep across a range of deflection angles to provide a number of views from a single pixel.
[0053] View multiplexer 804 includes triangular columns 808A-C of a material whose refraction index is controllable, e.g., by an electrical field. An example of such a material is liquid crystal. Triangular columns 808A-C are positioned between a layer 606 of transparent plastic or glass and a grooved layer 810 of transparent plastic or glass into which triangular grooves are made to provide space for triangular columns 808 A-C.
[0054] In front of layer 806 is an electrode layer 802. Behind layer 810 is an electrode layer 812. By selectively applying a charge to electrode layers 802 and 812, the refraction index of the material in triangular columns 808A-C can be varied.
[0055] The material within triangular columns 808A-C, its orientation set at manufacture, and the size and shape of triangular columns 808A-C are selected to provide a desired range of deflection across the range of electrical fields that can be produced across electrode layers 802 and 812. In effect, the material in triangular columns 808A-C are prisms whose degree of light defiection vary according to the electrical field between electrode layers 802 and 812.
[0056] In this illustrative embodiment, the desired range of deflection is 0.0- 2.0 degrees, the material within triangular columns 808A-C has a refraction index that varies from the refraction index of layers 806 and 810 to 0.1 above the refraction index of layers 806 and 810, and triangular columns 808 A-C have a cross-sections that are right triangles with an angle 816 of 20 degrees.
[0057] Timing diagram 900 (Figure 9) illustrates the time-multiplexing of pixel 216A using view multiplexer 804. Timing diagram 900 shows an electrical field between electrode layers 802 and 812, the corresponding angle of deflection of view multiplexer 804, and various views displayed by pixel 216A. The angle of deflection provided by view multiplexer 804 sweeps through a predetermined range, e.g., 0-2.0 degrees. Pixel 216A displays pixels of views N through N+3 in a synchronized manner such that pixel 216A displays a pixel of view N while view multiplexer 804 sweeps through deflection angles 0.0-0.5 degrees, displays a pixel of view N+l while view multiplexer 804 sweeps through deflection angles 0.5-1.0 degrees, displays a pixel of view N+2 while view multiplexer 804 sweeps through defiection angles 1.0- 1.5 degrees, and displays a pixel of view N+3 while view multiplexer 804 sweeps through deflection angles 1.5-2.0 degrees, after which view multiplexer 804 returns to provide a deflection of 0 degrees and pixel 216A displays a pixel of the next frame of view N.
[0058] It should be appreciated that, while pixel 216A is shown to time- mulitplex only four (4) views, pixel 216A can time-multiplex many more views, limited only by the switching rate of pixel 216A relative to a desired frame rate. In embodiments in which pixel 216A is implemented using one or more LEDs, e.g., in very large signage, pixel 216A can switch much more rapidly than an LCD pixel and can time -multiplex many more views. For example, some LEDs can switch at frequencies of 2.0MHz. Accordingly, a single LED (or a cluster of red, green, and blue LEDs) can provide 300 or more views of single pixel, limited only by the optical quality of lenticles 202A-C and the range of deflection angles and switching speed of view multiplexer 804.
[0059] Timing diagram 1000 (Figure 10) shows an alternative manner in which view multiplexer 804 can time-multiplex pixels of multiple views shown by pixel 216A. Once view multiplexer 804 sweeps through a range of deflection angles, e.g., 0-2.0 degrees, view multiplexer 804 sweeps back through the range in reverse direction, e.g., from 2.0 degrees to 0 degrees. In a synchronized manner, once pixel 216A switches through pixels of views N, N+1, N+2, and N+3, pixel 216A switches through pixels of a subsequent frame in reverse order, i.e., through views N+3, N+2, N+1, and N. [0060] If should be appreciated that view multiplexer 804 can cycle through angles of deflection in other ways, including stepped patterns. In addition, multiple instances of view multiplexer 804 can be stacked as are view multiplexers 204A-B (Figure 2) to provide greater ranges of cumulative defiection angles.
[0061] The above description is illustrative only and is not limiting. The present invention is defined solely by the claims which follow and their full range of equivalents. It is intended that the following appended claims be interpreted as including all such alterations, modifications, permutations, and substitute equivalents as fall within the true spirit and scope of the present invention.

Claims

2016/032423 Page 20 of 24 PCT/US2014/052504 CLAIMS What is claimed is:
1. A method for showing multiple views of a multi-view autostereoscopic image in a single physical pixel, the method comprising:
(a) causing the physical pixel to display a pixel of a first of the views during a first time interval;
(b) making the physical pixel viewable from a first limited viewing perspective for the first time interval;
(c) causing the physical pixel to display a pixel of a second of the views during a second time interval that is different from the first time interval; and
(d) making the physical pixel viewable from a second limited viewing perspective that is different from the first limited viewing perspective for the second time interval.
2. The method of Claim 1 further comprising: repeating steps (a)-(d) for each of two or more physical pixels of a display.
3. The method of Claim 1 further comprising: repeating steps (a)-(d) for each of two or more frames of a video signal. 2016/032423 Page 21 of 24 PCT/US2014/052504
4. The method of Claim 1 wherein steps (b) and (d) comprise: controlling polarity of light passing through one or more lenses of birefringent material from the physical pixel.
5. The method of Claim 4 where the lenses are prisms.
6. The method of Claim 1 wherein steps (b) and (d) comprise: controlling the refraction index of one or more lenses though which light passes from the physical pixel.
7. The method of Claim 6 where controlling comprises controlling an electrical field of the lenses.
8. The method of Claim 6 where the lenses are prisms.
9. A view multiplexer for enabling one or more physical pixels of a display to each display corresponding pixels of multiple views of a multi-view autostereoscopic image, the view multiplexer comprising: one or more lenses, each of which deflects light from at least one of the physical pixels at one or more predetermined angles in response to an electrical signal. 2016/032423 Page 22 of 24 PCT/US2014/052504
10. The view multiplexer of Claim 9 wherein the lenses are prisms.
11. The view multiplexer of Claim 9 wherein each of the lenses includes birefringent material; and further wherein the electrical signal controls polarity of light passing through the lenses from the physical pixels.
12. The view multiplexer of Claim 11 wherein the lenses are prisms.
13. The view multiplexer of Claim 9 wherein each of the lenses includes material whose refraction index varies in a varying electrical field; and further wherein the electrical signal controls the electrical field of each of the lenses.
14. The view multiplexer of Claim 13 wherein the lenses are prisms.
2016/032423 Page 23 of 24 PCT/US2014/052504
15. An autostereoscopic display comprising: a focus target; and a lenticular array that includes one or more lenticles, each of which focuses behind the focus target by a predetermined amount.
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