Classifications

• • 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]
• • 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]
  • H04N9/3141—Constructional details thereof
  • H04N9/315—Modulator illumination systems
• • 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
• • 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
  • G02B5/04—Prisms
  • G02B5/045—Prism arrays

Definitions

• the present invention relates to the field of analyzers for transmissive type LCD projection-type video image display devices, and particularly to an imaging optical system for a projection-type video image display device comprising such analyzers, as well as to a method of arranging such analyzers in the imaging optical system of a projection-type video image display device.
• This projection picture display is constituted in such a way that a picture is displayed by regulating random light emitted from a light source to unidirectional polarized light by an incident-side polarizing plate, controlling the polarizing direction thereof for each pixel by the light valve and transmitting the polarized light only in one direction of polarization by an emitting-side polarizing plate, enlarged and projected by a projection lens.
• the emitting-side polarizing plate is a reflection polarizing plate and inclined with respect to the surface of the light valve, heat is suppressed from being generated near the light valve and the emitting-side polarizing plate. Thus, a deterioration of reliability is suppressed.
• an object of the present invention to provide an improved imaging optical system for a projection-type video image display device.
• This object is achieved by providing an imaging optical system comprising a refractive analyzer device arranged to pass light of a first polarization mode in an imaging path and cause an angular deviation of light of a second polarization mode with respect to said imaging path, a reflective analyzer device, arranged at a separation distance from said refractive analyzer device along said imaging path, and arranged to pass light of the first polarization mode in said imaging path and reflect deviated light of the second polarization mode out of said imaging path.
• the separation distance required to deviate unwanted light out of said imaging path can be kept low, thereby enabling a compact design where the back focal length of an associated projection lens can be kept short, whereby the production costs of projection-type video image display devices can be reduced.
• Another object of the invention is to provide an improved method for configuring such analyzers in projection-type video image display devices.
• a method comprising the steps of: providing a refractive analyzer device arranged to pass light of a first polarization mode in an imaging path and cause an angular deviation of light of a second polarization mode with respect to said imaging path; providing a reflective analyzer device at a separation distance from said refractive analyzer device along said imaging path, said reflective analyzer being arranged to pass light of the first polarization mode in said imaging path and reflect deviated light of the second polarization mode out of said imaging path.
• Fig. 1 is a schematic view of a refractive analyzer
• Fig. 2 is a schematic view of a stacked refractive analyzer according to Figure 1;
• Fig. 3 is a schematic view of a first embodiment of an analyzer configuration for a projection-type video image display device
• Fig. 4 is a schematic view of a second embodiment of an analyzer configuration for a projection-type video image display device.
• Fig. 1 is a schematic view showing a basic constitution of a refractive analyzer
• a uniaxially oriented birefringent layer 2 is sandwiched between two transparent carrier substrates 3.
• Each substrate 3 has a fine-pitch "sawtooth” structure 4, deposited on their respective inner surfaces.
• the fine pitch "saw-tooth” structure 4 is preferably made of layers of polyimide plastic (PI).
• An incident light beam 5 containing p and s-polarized light is shown falling on the refractive analyzer 1.
• the material properties are selected in such a way that the first polarization mode, e.g.
• the p-polarized light beam 6 does not observe a large variation of refractive indices, and as such observes the refractive analyzer as a plane-parallel plate, and is thus passed on along an imaging path.
• the second polarization direction e.g. the s-polarized light 7, however, observes a large difference in refractive indices between the materials and is refracted in the interfaces, such that its direction of propagation is changed as the beam passes the refractive analyzer 1, causing an angular deviation with respect to the imaging path.
• this refractive analyzer 1 is intended to be arranged in the imaging optical system of a projection-type video image display device, the optical demands imposed on imaging properties are very stringent.
• Fig. 2 shows a solution for providing an increased change of direction of the second polarization light 7. This is achieved by stacking two or more of the refractive analyzers 1 in accordance with Figure 1. In this way, an increased degree of angular splitting can be achieved.
• the incident lightbeam 5, containing p and s-polarized light falls on the stack of refractive analyzers 1 and the unwanted second polarization direction, e.g. the s-polarized light beam 7, is deviated stepwise by each layer thereof.
• the wanted first polarization mode, e.g. the p-polarized light beam 6, passes straight through the refractive analyzer 1.
• Fig. 3 illustrates a first embodiment of a possible analyzer configuration shown in a simplified light path of a projection-type video image display device.
• the shown light path comprises a liquid crystal (LCD) light valve 8, a refractive analyzer 1 in accordance with Figure 1, a dichroic prism 9, a reflective analyzer 10 and a projection lens 11.
• the refractive analyzer 1 is used in combination with a reflective analyzer 10, e.g. a so-called Moxtek® plate.
• the refractive analyzer 1 and the reflective analyzer 10 are positioned at such a separation distance from each other that the dichroic recombination prism 9 fits in between them.
• An incident light beam 5 containing p and s-polarized light from the LCD light valve 8 falls on the refractive analyzer 1.
• the unwanted second polarization mode e.g. the s-polarization direction, illustrated by arrows 7
• the wanted first polarization mode e.g. the p-polarized light beam, illustrated by arrow 6.
• the wanted first polarization mode (p-polarized) light beam 6 passes through the projection lens 11 to be incident on a screen (not shown) while the unwanted second polarization mode (s-polarized) light beam is reflected out of the imaging path.
• Fig. 4 shows a second embodiment essentially corresponding to the Figure 3 embodiment but with the difference that the reflective analyzer 10 is arranged at an angle relative to the imaging path, whereby the deviation of the unwanted beam 7 can be further increased.
• a method for arranging analyzers in the imaging optical system of a projection-type video image display device comprises the steps of: providing a refractive analyzer device arranged to pass light of a first polarization mode (e.g. p-polarized light) in an imaging path and cause an angular deviation of light of a second polarization mode (e.g. s-polarized light) with respect to the imaging path; providing a reflective analyzer device at a separation distance from said refractive analyzer device along said imaging path, said reflective analyzer being arranged to pass light of the first polarization mode in the imaging path and reflect deviated light of the second polarization mode out of said imaging path.
• a first polarization mode e.g. p-polarized light
• a second polarization mode e.g. s-polarized light
• the method further comprises the step of providing a dichroic prism in said imaging path between said refractive analyzer and said reflective analyzer, thus providing said separation distance.
• the method comprises the step of providing a refractive analyzer which comprises at least one uniaxially oriented birefringent layer, where each respective birefringent layer is sandwiched between two transparent carrier substrates, each of which has a fine-pitch sawtooth structure deposited on their respective sides facing one of said birefringent layers.
• the method comprises the step of providing a refractive analyzer which comprises two or more uniaxially oriented birefringent layers.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Engineering & Computer Science (AREA)
• Multimedia (AREA)
• Signal Processing (AREA)
• Projection Apparatus (AREA)
• Polarising Elements (AREA)
• Liquid Crystal (AREA)

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Applications Claiming Priority (4)

Publications (1)

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Family Applications (1)

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• 2004
  • 2004-01-14 WO PCT/IB2004/050018 patent/WO2004068200A1/en not_active Application Discontinuation
  • 2004-01-14 JP JP2006502516A patent/JP2006517034A/ja active Pending
  • 2004-01-14 EP EP04702027A patent/EP1590694A1/en not_active Withdrawn
  • 2004-01-14 CN CNA200480002931XA patent/CN1742216A/zh active Pending
  • 2004-01-14 KR KR1020057013942A patent/KR20050090012A/ko not_active Application Discontinuation
  • 2004-01-20 TW TW093101598A patent/TW200419290A/zh unknown

Non-Patent Citations (1)

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