Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/24—Coupling light guides
  • G02B6/26—Optical coupling means
  • G02B6/27—Optical coupling means with polarisation selective and adjusting means
  • G02B6/2706—Optical coupling means with polarisation selective and adjusting means as bulk elements, i.e. free space arrangements external to a light guide, e.g. polarising beam splitters
  • G02B6/2713—Optical coupling means with polarisation selective and adjusting means as bulk elements, i.e. free space arrangements external to a light guide, e.g. polarising beam splitters cascade of polarisation selective or adjusting operations
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N9/00—Details of colour television systems
  • H04N9/12—Picture reproducers
  • H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
  • G02B27/28—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising
  • G02B27/283—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising used for beam splitting or combining
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B5/00—Optical elements other than lenses
  • G02B5/30—Polarising elements
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/24—Coupling light guides
  • G02B6/26—Optical coupling means
  • G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
  • G02B6/293—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
  • G02B6/29346—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means operating by wave or beam interference
  • G02B6/29361—Interference filters, e.g. multilayer coatings, thin film filters, dichroic splitters or mirrors based on multilayers, WDM filters
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/24—Coupling light guides
  • G02B6/42—Coupling light guides with opto-electronic elements
  • G02B6/4298—Coupling light guides with opto-electronic elements coupling with non-coherent light sources and/or radiation detectors, e.g. lamps, incandescent bulbs, scintillation chambers
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N9/00—Details of colour television systems
  • H04N9/12—Picture reproducers
  • H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
  • H04N9/3102—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM] using two-dimensional electronic spatial light modulators
  • H04N9/3111—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM] using two-dimensional electronic spatial light modulators for displaying the colours sequentially, e.g. by using sequentially activated light sources
  • H04N9/3117—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM] using two-dimensional electronic spatial light modulators for displaying the colours sequentially, e.g. by using sequentially activated light sources by using a sequential colour filter producing two or more colours simultaneously, e.g. by creating scrolling colour bands

Definitions

• the present invention relates to projection display systems, and more particularly relates to an integrated beam splitter and polarizer for a single panel scrolling color projection display system.
• a single panel scrolling color projection display system is characterized by a single light modulator panel such as a liquid crystal display (LCD) panel having a raster of 0 individual picture elements or pixels, which panel is illuminated by horizontally elongated red, green and blue illumination bars or stripes.
• the stripes are continuously scrolled vertically across the panel while the illuminated rows of pixels are synchronously addressed with display information corresponding to the color of the then incident stripe.
• LCD liquid crystal display
• Such single panel systems are to be distinguished from the more conventional three-panel systems, in which separate red, green and blue beams each fully illuminate and are modulated by a separate light modulator panel. The modulated beams are then superimposed on a display screen to produce a full color display.
• incoming white light is split into separate 5 red, green and blue color components by a light engine using dichroic elements.
• the illumination architecture for a light engine 1 for such a scrolling color projector is shown schematically in Fig. 1.
• White light from source S is split into a blue component B and a green red component G/R by dichroic element 2.
• the B component is directed by lens 3 and mirror 4 to prism scanner 5.
• the G/R component is passed by dichroic element 2 0 through lens 6 to dichroic element 7, which splits the G/R component into a green component G and a red component R.
• the G component is reflected by element 7 to prism scanner 8, while the red component is passed through dichroic element 7 to prism scanner 9.
• the scanned R, G, B components are then directed to recombination dichroic elements 10 and 11 by mirror 12 and relay lenses 13 through 17.
• the dichroic elements and mirrors are tilted at a 45 degree angle to the beam path.
• the spectral response of a tilted dichroic filter depends strongly on the incident angle of the light. Therefore, it is not possible to effectively divide white light into non-overlapping color bands when using these filters in divergent light, which is necessary for high light throughput. Consequently, either the color performance or the optical efficiency of the system must be sacrificed.
• the light modulating panel is an LCD
• the light must also be polarized.
• Polarization conversion is achieved in a separate step, typically using an optical element known as a McNeill prism.
• McNeill prism an optical element known as a McNeill prism.
• the efficiency of these polarization conversion elements decreases as the light being treated becomes more divergent.
• a typical polarization conversion arrangement 20 is shown in Fig. 2.
• Output light from a light engine which constitutes an image of scrolling bands of R, G, and B light, is directed through polarizer 22 to a polarizing beam splitter (PBS) 23, having an internal polarized beam splitting surface 23 a.
• Polarizer 22 converts the unpolarized light to light of one polarization state, eg. S.
• Surface 23a passes this S light to light modulator panel 24, which modulates the light in accordance with a display signal, and reflects the modulated light back to the PBS 23.
• panel 24 changes the polarization state of the light from S to P, and surface 23a reflects the light out of the PBS 23 to a projection lens for display.
• Polarization conversion is often carried out in combination with a light integration step using an integrating array.
• Light integration is intended to produce light beams having a stripe-shaped cross-section of uniform brightness.
• polarization conversion in combination with light integration arrays does not work well with beams having cross-sections with such large aspect ratios.
• an integrated beam splitting and polarization conversion system 10 for a projection display system comprising: a light guide array 32 comprising at least four light guide elements (W, Gr, Gg, Gb), a first of the light guide elements (W) having a light exit face 34, and second, third and fourth light guide elements having light entrance faces (36, 38, 40) with a wide aspect ratio (l/w> 2), the entrance faces (36, 38, 40) each having a first side (36a, 38a, 40a) and a second side (36b, 38b, 40b) ; a polarizing beam splitter 42 for converting white light from exit face 34 of light guide element W into a first beam having a first state of polarization and a second beam having a second state of polarization, the polarizing
• the light guide W is preferably positioned below the light guides (Gr, Gg, Gb), but may alternatively positioned above or to one side of the light guides (Gr, Gg, Gb).
• the filters (Rl, Gl, BI) and (R2, G2, B2) of filter sets FI and F2 are preferably positioned in series in the order B, G, R from the exit faces 48 and 50, respectively, but alternatively may be positioned in another order, such as B, R, G, from the exit faces 48 and 50, respectively.
• a projection display system 50 comprising: a source 52 of white light; an integrated beam splitting and polarization conversion system 54 according to the first aspect of the invention, system 54 for splitting the source 52 into polarized red, green and blue beams having a cross-section with a wide aspect ratio; a light modulating panel 56, for modulating light in accordance with a display signal; means 58 for continuously and sequentially scrolling the red, green and blue beams across the light modulating panel 56; and a projection lens 60 for projecting the modulated light onto a display surface.
• the light modulating panel 56 is preferably a liquid crystal display panel, although other types of display panels such as deformable mirror devices may alternatively be employed.
• the means 58 for scrolling the beams may be a single large rotating prism, or alternatively, three smaller rotating prisms, one for each of the red, green and blue beams.
• the projection display system 50 may include a light guide system 62 for guiding the red, green and blue beams from the beam splitting and polarization conversion system 54 to the scrolling means 58.
• a loss-less, etendue-preserving light guide suitable for use in the present invention is described in co-pending United States Patent Application Serial
• the projection display system 50 may also include means 64 for synchronously and continuously supplying red, green and blue components of a color display signal to the light modulating panel 56 during scrolling of the red, green and blue light beams across the light modulating panel 56.
• Suitable means are described, for example, in United States Patents 5,410,370 and 5,416,514, already referenced hereinabove.
• Fig. 1 is a schematic representation of the illumination architecture of a light engine for a single panel scrolling color projection system of the prior art;
• Fig. 2 is a schematic representation of a polarization conversion architecture for a single panel scrolling color projection system of the prior art
• Figs. 3 A through 3E are different views of a schematic illustration of one embodiment of an integrated beam splitter and polarizer for a projection display system of the invention
• FIGs. 4A through 4G are different views of a schematic illustration of additional embodiments of an integrated beam splitter and polarizer for a projection display system of the invention.
• Fig. 5 is a block diagram illustrating one embodiment of a projection display system incorporating an integrated beam splitter and polarizer of the invention.
• a light guide array 32 includes four light guide elements (W, Gr, Gg, Gb).
• Light guide element W has a light exit face 34, and light guide elements Gr, Gg, Gb have light entrance faces 36, 38 and 40, respectively.
• entrance faces 36, 38 and 40 have a first side (36a, 38a, 40a) and a second side (36b, 38b, 40b). These entrance faces also have a wide aspect ratio characterized by a length-to-width ratio of 2 or greater (1 w >_ 2), to enable the stripe-shaped beam cross-sections needed for scrolling the light modulator panel.
• the integrated beam splitter and polarizer 30 also includes a polarizing beam splitter (PBS) 42 for converting white light from exit face 34 of light guide element W into a first beam having a first state of polarization and a second beam having a second state of polarization.
• PBS polarizing beam splitter
• Unpolarized white light (U) from exit face 14 of light guide W is imaged onto entrance face 44 of PBS 42, and collimated by a second lens L2.
• Lens L2 also helps to preserve tele-centricity of the light.
• the U light Upon striking the internal polarizing-beam-splitting side 46b of surface 46, the U light is converted to S light and reflected toward exit face 48 and filter set FI.
• Filters BI, Gl and Rl separate out blue, green and red light, respectively, from the S-polarized white light.
• Filters BI, Gl and Rl are retro-reflective and tilted at different angles so that after retro-reflection, the light is re-imaged by lens LI into a corresponding light guide.
• Filters BI, Gl and Rl are also tilted in a plane normal to the drawing, such that the light falls into the left half of light guides (36a, 38a, 40a) (view A- A).
• P-polarized light (Fig. 3B) is transmitted by surface 46 of PBS 44 to exit face 50.
• a second filter set F2 is positioned opposite exit face 50, and the individual retro-reflective filters B2, G2, R2 are tilted so that, after retro-reflection, the light is again transmitted by surface 46 and re-imaged by lens LI into the right-hand half of the corresponding light guides (36b, 38b, 40b).
• a wave-plate 52 (Fig. 3E) placed before the right-hand half of light guide array 32 transforms the polarization state of the P light to S light, so that the polarization state of all of the light entering the light guides Gr, Gg, Gb matches, as indicated by the matched cross hatching on the entrance faces 36, 38 and 40 (Fig. 3F).
• FIG. 4A through 4G An alternative, side-by-side, disposition of the light guides is shown in the system 60 of Figs. 4A through 4G.
• Figs. 4A and 4B are side views similar to those of Figs. 3 A and 3B, except for the different placement of the light guide W in the array 62, and the order of placement of the filters in the filter sets FI and F2.
• the positions of filters R and G are switched from those of the previous embodiment.
• Fig 4C is a top view of the arrangement, showing light guide W placed on the left side of the array 62.
• Figs. 4D through 4G are section views along A-A, with Figs. 4E and 4G showing the unmatched polarization states prior to wave plate 72, and Figs. 4D and 4F showing the matched polarization states after wave plate 72, for the side and top views, respectively.
• the above integrated systems combine both the polarization conversion and color splitting functions into one compact unit. Moreover, the use of dichroic filters for color separation is eliminated, and the accompanying degradation of color purity in divergent light systems is avoided.
• Fig. 5 shows a projection display system 80 incorporating an integrated beam splitter and polarizer 82 in accordance with the invention, a light modulation panel 84, means 86 for scrolling colored light beams across the panel 84, and a projection lens 88 for projecting the modulated light onto a display surface.
• the system 80 also includes a light guide system 90 for guiding white light from a source S to the integrated beam splitter and polarizer 82, and for guiding colored light beams from the integrated beam splitter and polarizer 82 to means 86.
• Addressing means 92 is provided for supplying display signals to the panel 84 synchronously with the impingement of the scrolling bands of colored light, to produce a color display image.

Applications Claiming Priority (3)

Publications (1)

Family

ID=32682203

Family Applications (1)

Country Status (7)

Family Cites Families (4)

• 2003
  • 2003-12-11 WO PCT/IB2003/006056 patent/WO2004059989A1/en not_active Application Discontinuation
  • 2003-12-11 CN CNA2003801066595A patent/CN1729699A/zh active Pending
  • 2003-12-11 KR KR1020057011271A patent/KR20050088391A/ko not_active Application Discontinuation
  • 2003-12-11 AU AU2003303454A patent/AU2003303454A1/en not_active Abandoned
  • 2003-12-11 JP JP2004563464A patent/JP2006510949A/ja active Pending
  • 2003-12-11 EP EP03813961A patent/EP1579700A1/de not_active Withdrawn
  • 2003-12-17 TW TW092135786A patent/TW200507656A/zh unknown

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events