Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL 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
  • G02F1/00—Devices 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
  • G02F1/01—Devices 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 
  • G02F1/13—Devices 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
  • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
  • G02F1/1333—Constructional arrangements; Manufacturing methods
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL 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
  • G02F1/00—Devices 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
  • G02F1/01—Devices 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 
  • G02F1/13—Devices 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
  • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
  • G02F1/1333—Constructional arrangements; Manufacturing methods
  • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
  • G02F1/133526—Lenses, e.g. microlenses or Fresnel lenses
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL 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
  • G02F1/00—Devices 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
  • G02F1/01—Devices 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 
  • G02F1/13—Devices 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
  • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
  • G02F1/1333—Constructional arrangements; Manufacturing methods
  • G02F1/133371—Cells with varying thickness of the liquid crystal layer
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL 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
  • G02F1/00—Devices 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
  • G02F1/01—Devices 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 
  • G02F1/13—Devices 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
  • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
  • G02F1/1333—Constructional arrangements; Manufacturing methods
  • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors

Definitions

• This invention relates to display devices in which a focusing arrangement provides direction of light from the pixels of the display panel.
• a lens is provided over a single pixel, it can provide an enlargement function. If a lens is provided over multiple pixels, it can direct the display output from different pixels to different spatial locations. This is the way an autostereoscopic display operates.
• a known example of focusing arrangement for use in an autostereoscopic display is an array of elongate lenticular elements which extend parallel to one another and overlie the display pixel array. The display pixels are observed through these lenticular elements.
• the lenticular elements are provided as a sheet of elements, each of which comprises an elongate semi-cylindrical lens element.
• the lenticular lens elements (“lenicules") extend in the column direction of the display panel, with each lenticular element overlying a respective group of two or more adjacent columns of display pixels.
• the display pixels in each column provide a vertical slice of a respective two dimensional sub-image.
• the lenticular sheet directs these two slices and corresponding slices from the display pixel columns associated with the other lenticules, to the left and right eyes of a user positioned in front of the sheet, so that the user observes a single stereoscopic image.
• the sheet of lenticular lens elements thus provides a light output directing function.
• each lenticule is associated with a group of four or more adjacent display pixels in the row direction. Corresponding columns of display pixels in each group are arranged appropriately to provide a vertical slice from a respective two dimensional sub-image. As a user's head is moved from left to right, a series of successive, different, stereoscopic views are perceived creating, for example, a look-around impression.
• a problem with the use of focusing arrangements is that different viewing locations correspond to light paths which are focused to different display panel areas, and in particular, with different light propagation angles through the LC layer of the display panel. These different light propagation angles give rise to different path lengths, and therefore different amounts of light modulation (i.e. phase change) by the LC material.
• LCD's work perfectly from the front because the visible light from the front has travelled exactly the correct distance through the LC material. For viewing from other angles, the performance degrades.
• a display device comprising: a liquid crystal display panel having an array of display pixel elements for producing a display and comprising a liquid crystal display layer; and - a lens arrangement provided over the display panel and comprising lens elements, which provides focusing from different viewing locations to different regions beneath the lens elements, wherein the thickness of the liquid crystal display layer is greater at a position corresponding to a centre of a lens element than at a position corresponding to an edge of the lens element.
• the display panel can comprise the liquid crystal display layer between transparent electrodes, wherein one electrode is shaped to define a non-uniform electrode spacing.
• the non-uniform spacing can thus be the result of a modification to the manufacturing process.
• a smallest dimension of each lens element can correspond to a dimension of a single black and white pixel or a single color sub-pixel. This means the output from each pixel or sub-pixel is controlled to improve the uniformity from different viewing directions.
• a smallest dimension of each lens element can corresponds to the dimension of a group of black and white pixels or a group of color sub-pixels. In this way, different pixels or sub-pixels are imaged to different spatial locations, so that different images are provided to different locations, but with more uniform light modulation properties for the different viewing locations.
• each lens element can comprises a lenticular lens in which the smallest dimension is the width.
• the display device can comprise an autostereoscopic display, wherein the lens arrangement directs the output from different pixels or sub-pixels to different spatial positions to enable a stereoscopic image to be viewed.
• Fig. 1 is a schematic perspective view of a known autostereoscopic display device
• Fig. 2 shows how a lenticular array provides different views to different spatial locations
• Fig. 3 shows a first example of display device according to the invention
• Fig. 4 shows a second example of display device according to the invention
• the invention provides a liquid crystal display device in which a lens arrangement is provided over a display panel.
• the thickness of the liquid crystal display layer is greater at a position corresponding to a centre of a lens element than at a position corresponding to an edge of the lens element. This means the length of the light path through the liquid crystal layer can be substantially the same for different viewing directions, or can be selected to provide the same modulation effect from these different viewing directions.
• the invention is of particular interest for autostereoscopic display devices.
• Fig. 1 is a schematic perspective view of a known direct view autostereoscopic display device 1.
• the known device 1 comprises a liquid crystal display panel 3 of the active matrix type that acts as a spatial light modulator to produce the display.
• the display panel 3 has an orthogonal array of display pixels 5 arranged in rows and columns. For the sake of clarity, only a small number of display pixels 5 are shown in the Figure. In practice, the display panel 3 might comprise about one thousand rows and several thousand columns of display pixels 5.
• the structure of the liquid crystal display panel 3 is entirely conventional.
• the panel 3 comprises a pair of spaced transparent glass substrates, between which an aligned twisted nematic or other liquid crystal material is provided.
• the substrates carry patterns of transparent indium tin oxide (ITO) electrodes on their facing surfaces.
• ITO transparent indium tin oxide
• Polarizing layers are also provided on the outer surfaces of the substrates.
• Each display pixel 5 comprises opposing electrodes on the substrates, with the intervening liquid crystal material there between.
• the shape and layout of the display pixels 5 are determined by the shape and layout of the electrodes.
• the display pixels 5 are regularly spaced from one another by gaps.
• Each display pixel 5 is associated with a switching element, such as a thin film transistor (TFT) or thin film diode (TFD).
• TFT thin film transistor
• TFD thin film diode
• the display pixels are operated to produce the display by providing addressing signals to the switching elements, and suitable addressing schemes will be known to those skilled in the art.
• the display panel 3 is illuminated by a light source 7 comprising, in this case, a planar backlight extending over the area of the display pixel array. Light from the light source 7 is directed through the display panel 3, with the individual display pixels 5 being driven to modulate the light and produce the display.
• a light source 7 comprising, in this case, a planar backlight extending over the area of the display pixel array. Light from the light source 7 is directed through the display panel 3, with the individual display pixels 5 being driven to modulate the light and produce the display.
• the display device 1 also comprises a lenticular sheet 9, arranged over the display side of the display panel 3, which performs a view forming function.
• the lenticular sheet 9 comprises a row of lenticular elements 11 extending parallel to one another, of which only one is shown with exaggerated dimensions for the sake of clarity.
• the lenticular elements 11 are in the form of convex cylindrical lenses, and they act as a light output directing means to provide different images, or views, from the display panel 3 to the eyes of a user positioned in front of the display device 1.
• the autostereoscopic display device 1 shown in Fig. 1 is capable of providing several different perspective views in different directions.
• each lenticular element 11 overlies a small group of display pixels 5 in each row.
• the lenticular element 11 projects each display pixel 5 of a group in a different direction, so as to form the several different views.
• Fig. 2 shows the principle of operation of a lenticular type imaging arrangement as described above and shows the backlight 20, LCD display device 24 and the lenticular array 28.
• Fig. 2 shows how the lenticular arrangement 58 directs different pixel outputs to different spatial locations.
• Fig. 3 shows a first example of display device of the invention, from the top view of a single LCD (sub) pixel.
• the display panel 3 comprises a lower electrode 30, an LC layer 32 and a top electrode 34.
• the electrodes are transparent, for example formed from ITO and provided on respective glass substrates.
• Fig. 3 also shows a color filter 36 and a black mask layer 38.
• the lens 11 in this example has a width which corresponds to a dimension of the single pixel shown.
• the single pixel is a single color sub-pixel, but in a black and white example the pixel would be a single complete pixel.
• the lens element 11 provides focusing from different viewing locations to different regions beneath the lens element.
• the light paths associated with two viewing directions are shown.
• the bold lines represent the light paths for a viewing position normal to the display, and the focusing is to the middle of the pixel.
• the dotted lines represent the light paths for a viewing position to one lateral side of the display, and the focusing is to the edge of the pixel.
• the thickness of the liquid crystal display layer is greater at a position corresponding to a centre of a lens element than at a position corresponding to an edge of the lens element. This means that the lengths of the light paths can be made equal.
• the different spacing is achieved by a non-flat lower electrode 30, in particular having a raised profile at the edges.
• the non-flat electrode can be formed using a shaped foil onto which the electrode is deposited.
• the production of 3D lens foils is becoming easier and cheaper.
• These types of foil can also be used to provide a shaped display electrode to give the desired nonuniform spacing.
• the technology for 3D lenticular foils can be used for a 2D implementation (Fig. 3) or a 3D implementation (Fig. 4) of this invention.
• the shaped electrode can be formed by modifying the deposition of the electrode layer, so that it has different thickness at different locations. This could be achieved by multiple deposition steps of the ITO electrode, or by depositing a thicker ITO electrode and applying photolithographic patterning to create the desired profile. Photo- curable materials with patterned exposure can also be used to form different thicknesses. Standard techniques for creating non-flat surfaces on flat underlying substrates will be completely routine to those skilled in the art.
• the lens can be cylindrical, i.e. in the form of a lenticular lens, so that the uniform angle performance is obtained for different lateral viewing positions.
• spherical (or similar) lenses could be used to provide improved uniformity for different lateral as well as vertical viewing locations.
• the lens element focuses the light paths for a given viewing direction to quite a wide region, as seen schematically in Fig. 3.
• This light cone for each viewing direction can be reduced by using a lens not bigger than the color filter 36 and/or increasing the lens distance (so that the angles of divergence of the light paths are reduced).
• an increased lens distance will result in a reduced range of viewing angles.
• the lens structure cannot be mounted too high above the LCD panel to avoid pixels under neighboring lenses being visible (i.e. viewing the wrong pixels through a lens).
• Fig. 4 shows schematically how this can be implemented.
• each lens element 11 again comprises a lenticular lens.
• the invention can be applied to many different designs of LCD.
• it can be applied to flexible LCDs having plastics substrates as well as more conventional glass substrate LCDs.
• the complete LCD stack can be curved.
• the non-uniform cell spacing can be achieved with a structured lower electrode (as shown) or a structured top electrode.
• the shaping can be chosen such that the path length is substantially the same.
• the polarization modulation will also differ for different angles of propagation through the LC cell, so the overall aim of creating uniform light modulation effect at different angles may not imply fixed path length. Instead, a more complex profile may be used.
• the invention can enable an ultra-high viewing angle display to be formed, with improved image quality at steep angles. This is a major benefit for 2D and 3D displays.

Landscapes

• Physics & Mathematics (AREA)
• Nonlinear Science (AREA)
• Mathematical Physics (AREA)
• Chemical & Material Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• General Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Liquid Crystal (AREA)
• Testing, Inspecting, Measuring Of Stereoscopic Televisions And Televisions (AREA)
• Devices For Indicating Variable Information By Combining Individual Elements (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (1)

Family

ID=42331015

Family Applications (1)

Country Status (8)

Cited By (1)

Families Citing this family (1)

Citations (5)

• 2010
  • 2010-05-21 BR BRPI1008205A patent/BRPI1008205A2/pt not_active IP Right Cessation
  • 2010-05-21 WO PCT/IB2010/052268 patent/WO2010136944A1/en active Application Filing
  • 2010-05-21 CN CN2010800233938A patent/CN102449539A/zh active Pending
  • 2010-05-21 RU RU2011153669/07A patent/RU2011153669A/ru not_active Application Discontinuation
  • 2010-05-21 KR KR1020117030976A patent/KR20120027394A/ko not_active Application Discontinuation
  • 2010-05-21 EP EP10727901A patent/EP2435877A1/en not_active Withdrawn
  • 2010-05-21 JP JP2012512494A patent/JP2012528348A/ja not_active Withdrawn
  • 2010-05-25 TW TW099116712A patent/TW201107836A/zh unknown

Patent Citations (5)

Also Published As

Similar Documents

Legal Events