EP1410097A1 - Lampes doubles a projection - Google Patents

Lampes doubles a projection

Info

Publication number
EP1410097A1
EP1410097A1 EP00918456A EP00918456A EP1410097A1 EP 1410097 A1 EP1410097 A1 EP 1410097A1 EP 00918456 A EP00918456 A EP 00918456A EP 00918456 A EP00918456 A EP 00918456A EP 1410097 A1 EP1410097 A1 EP 1410097A1
Authority
EP
European Patent Office
Prior art keywords
lamp
orientation
polarized
output
lamps
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Withdrawn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
EP00918456A
Other languages
German (de)
English (en)
Inventor
Michael H. Kalmanash
Vijay M. Sethna
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.)
Rockwell Collins ElectroMechanical Systems Inc
Original Assignee
Kaiser Aerospace and Electronics 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 Kaiser Aerospace and Electronics Corp filed Critical Kaiser Aerospace and Electronics Corp
Publication of EP1410097A1 publication Critical patent/EP1410097A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/74—Projection arrangements for image reproduction, e.g. using eidophor
    • H04N5/7416—Projection arrangements for image reproduction, e.g. using eidophor involving the use of a spatial light modulator, e.g. a light valve, controlled by a video signal
    • H04N5/7441—Projection arrangements for image reproduction, e.g. using eidophor involving the use of a spatial light modulator, e.g. a light valve, controlled by a video signal the modulator being an array of liquid crystal cells
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/74—Projection arrangements for image reproduction, e.g. using eidophor
    • 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
    • G02F1/1336—Illuminating devices
    • G02F1/133626—Illuminating devices providing two modes of illumination, e.g. day-night

Definitions

  • the present invention is in the field of information display systems, and more particularly, in the field of projection displays.
  • Liquid crystal projectors are widely used as information display devices because of their compactness, light weight, high resolution and brightness.
  • the light source for most of these projectors is an arc lamp, which may be either metal halide, high pressure mercury vapor or xenon. Desired arc lamp characteristics are compact size, high efficiency, high (lumen) light output, broad (full-color) spectral gamut and short arc gap for efficient light utilization.
  • Such lamps are available ftom a number of commercial sources, includingN.V. Philips Gloeilampenfabriken, Osram, Ushio and Welch-Allyn, among others.
  • the second lamp was physically exchanged with the failed primary lamp as in the patents to P.M. Field etal, Pat. No. 3,294,966; LiDonnici, Pat. Nos. 3,914,645 and 4,518,233; Gehlyetal., Pat. No. 5,032,962; Dreyer, Jr. et al, Pat. No. 5,135,301; and Rodriguez, Jr. et al, Pat. No. 5,241,333.
  • a similar approach was used with an LCD projector in the patent to Park et al, Pat. No. 5,296,883, in which a plurality of arc tubes are mounted on a rotatable plate and each can be automatically brought into position as the primary light source when the arc tube in use experiences a failure.
  • the current invention provides an all-electronic means of selection between two lamps for a projection system, and also provides a wide dimming range for arc lamp projectors. It offers the potential for automatic lamp substitution in the event of a lamp failure.
  • LCD projectors operate on the basis of modulating polarized light.
  • a polarization means (“output polarizer”) is therefore almost always inserted between the projector lamp and the projector image sources (microdisplays).
  • output polarizer a pair of lamps are arranged along the side and the rear of a polarizing beam splitter.
  • the p-polarized component (“P") of the first lamp output is transmitted through the beam splitter while the second ("S") component is reflected.
  • the s-polarized component of the second lamp output is reflected by the beam splitter while the ("P") component is transmitted.
  • the output path of the beam splitter thus comprises the "P" component of the first lamp and the "S" component of the second lamp.
  • a linear polarizer (“output polarizer”) is placed in the output path from the polarizing beam splitter, oriented to pass p-polarized light and to block s-polarized light.
  • a liquid crystal polarization rotator is interposed in the output path of the beam splitter and at 0 ° rotation passes the "P" polarized output beam from the first lamp through the output polarizer which is transparent for "P" polarized light.
  • the rotator is oriented toward a 90° rotation, progressively attenuating the p-polarized component of light passing through until, at 90° rotation, the "P" polarized component is zero.
  • the "S" polarized second lamp light component is reflected in the beam splitter and is now the light in the output path while the "P" component is transmitted in a direction orthogonal to the light path.
  • the rotator at 0° rotation will block the "S" polarized light. Rotating the polarization to 90° will convert the "S" polarized light to p-polarization, permitting it to pass through the output polarizer in the desired orientation, and an intermediate setting will dim the light. Accordingly, dimming takes place as the rotator goes from 90° to 0° rotation.
  • the rotator can be a one half wave plate which is mechanically rotated through 90°.
  • an untwisted nematic LCD with its director axis at 45 ° to the "S" and "P" polarization states could be a half-wave retarder ( 90° rotation) when a first voltage is applied, and a zero-wave retarder (0° rotation) when a second voltage is applied.
  • a twisted nematic (TN) LCD can serve the same function.
  • TN twisted nematic
  • the 2nd lamp were to be a backup lamp to replace the 1st lamp in the event of failure
  • switching between lamps could automatically switch the lamp ballast from the 1st lamp to the 2nd lamp.
  • a system could be devised whereby the failure of the 1st lamp could automatically switch the ballast to the second lamp and cause the rotator to an alignment that was the inverse of its original setting.
  • the 1st lamp might be a high intensity day use lamp while the 2nd lamp might be a low intensity lamp, intended for night use.
  • the 2nd lamp could be filtered for NVTS compatibility.
  • the lamps could be powered individually or could be powered simultaneously, with the polarization rotator selecting which lamp would be the illumination source.
  • the present invention has the ability to not only select one of two sources, but also the ability to transition smoothly between the illumination of one and the illumination of the other with partial illumination of both as an option
  • the present system could be employed in a system wherein one of the sources operated at a first frequency band representing a first color and the second source operated at a second frequency band representing a second color.
  • light of the first color, light of the second color, or any combination of the two could be provided to a utilization device.
  • the utilization device might present a multicolor image using only a single monochrome channel by high speed switching between the sources or to a setting for any desired combination of the two sources.
  • FIGURE 1 is a diagram of a preferred embodiment of a dual lamp system according to the present invention
  • FIGURE 2 shows an electronic polarization rotator according to an alternative embodiment of the present invention
  • FIGURE 3 shows an alternative electronic polarization rotator using a twisted nematic LCD
  • FIGURE 4 is a diagram of a system in which lamp failure is automatically sensed
  • FIGURE 5 is a diagram of an alternative system in which the first lamp is a day lamp and the second lamp is a night lamp.
  • FIGURE 1 there is shown a dual lamp system 10 according to a preferred embodiment of the present invention.
  • Two lamps 12, 14, are placed on adjacent sides of a polarizing beam splitter (PBS) 16.
  • PBS polarizing beam splitter
  • a polarization rotator 18 is set by a mechanical driver device 20 to 0° rotation and the p-component of the first lamp 12 emission is transmitted through an output p-polarizer 22 and onward to the rest of the projection system.
  • the polarization rotator 18 can also be used to dim the light output from the first lamp 12, considering that the light exiting the PBS 16 from that lamp is p-polarized. If the polarization rotator 18 is set to 0° rotation, then this p-polarized light passes with high efficiency through the output polarizer 22.
  • the polarization rotator 18 serves as a dimmer for first lamp 12 emission.
  • first lamp 12 is turned off or has failed and second lamp 14 is turned on.
  • the s-component of second lamp 14 emission is reflected from the PBS 16 (toward the projection system).
  • the output polarizer 22 For this light to be transmitted through the output polarizer 22, it must be converted to p-polarization. This is done by driving the polarization rotator 18 to 90° rotation, which then becomes the condition for maximum transmittance of second lamp 14 emission.
  • the polarization rotator can be used to dim the second lamp 14 emission by adjusting its rotation toward 0°.
  • the polarization rotator 18 can be mechanized in many different ways. In the simplest embodiment, it is simply a half wave plate which is mechanically rotated by drive means 20. It is known that a half-wave plate has the property of rotating polarized light symmetrically around its slow axis. Thus, for example, setting the axis of the half- wave plate to 45° with respect to the polarized light output of the PBS 16 would result in a net rotation of light by
  • a polarization rotator has no moving parts This might be preferred in many applications and can be mechanized with liquid crystal devices (LCDs).
  • LCDs liquid crystal devices
  • an untwisted nematic LCD 28 with its director axis set at 45° to the polarized light from the PBS 16' can be designed to be a half-wave retarder in the unpowered state, thereby acting as a 90° rotator in this state.
  • the retardation is gradually reduced toward zero, so that in its fully-on state the LCD 28 is essentially a 0° rotator.
  • a twisted nematic (TN) LCD 28' can serve the same function.
  • the TNLCD 28' acts via optical waveguiding to control the polarization of light transmitted through it as a function of applied RMS voltage.
  • the TNLCD 28' would be constructed with a 90° twist and its director axis (at either substrate) would be aligned to be in line with the polarized light out of the PBS 16'.
  • Full voltage would correspond to 0° polarization rotation.
  • Zero voltage would correspond to 90° polarization rotation.
  • a sensor 66 could monitor the illumination from the first lamp 62.
  • the sensor output signal could be applied to a switch circuit 68 which normally couples ballast 60 output to the first lamp 62.
  • the switch 68 applies the output of the ballast 60 to the second lamp 64.
  • a signal can be sent to the rotator to change to the setting which passes the second lamp 64 illumination.
  • the ballast would be nominally connected to the first lamp, for example, and the output current in the ballast would be sensed.
  • the ballast would be automatically disconnected from the first lamp and instead connected to the second lamp (via relays or similar means), and simultaneously the polarization rotator would be automatically set to the inverse rotation from its previous setting, to ensure the net light output remains unchanged.
  • the first and second lamps need not be identical.
  • One such configuration is shown inFIGURE 5, in which the first lamp 12" is a high intensity lamp for high ambient daytime viewing (high luminance) and the second lamp 14" is a low intensity lamp for night viewing (low luminance).
  • first lamp 12 Since the power dissipation of first lamp 12" would be much lower than for second lamp 14", this would be a more efficient system than one which merely attenuated the high intensity lamp output for low luminance. Additionally, for military applications the emission from second lamp 14" (night lamp) could be filtered for NVIS compatibility, if desired, without affecting the broad color gamut of first lamp 12" in daytime use.
  • the lamps could be powered individually, depending on which one is needed, or they could be powered simultaneously, relying on the selectivity of the polarization rotator and the output polarizer to choose the correct lamp emission. Moreover, for optimum power utilization, the lamps would be used alternatively so that the unneeded night second lamp 14" would not be powered while the day first lamp 12" was being operated, and vice versa.
  • FIGURE 5 An alternative embodiment, for which FIGURE 5 could also be illustrative, would be s system in which the first lamp 12" is of a first color, say “red” and the second lamp 14" is a second color, say “green", the system could provide an output of red or green or any shade which combined the two colors.
  • the color of the system could be selected by the setting of the rotator. If the rotator could be switched cyclically as between a plurality of settings, the system could provide, in a single monochrome channel, a series of color images which, when viewed, would appear to be multicolored.
  • a novel utilization of a polarizing beam splitter to selectively enable one of a pair of possible light sources.
  • the sources are substantially identical and one can be instantly employed if the other ceases to operate.
  • each source can have different characteristics and the output beam can go from light of one source through light from both sources to light from the other source by adjusting a polarization rotator.
  • one of the sources maybe considered a "day” source and be substantially brighter than the other source which would be considered a "night” source. If NVIS compatibility is desired, appropriate infra red filters could be inserted between the night source and the beam splitter input face.

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Liquid Crystal (AREA)

Abstract

Une source lumineuse à deux lampes utilise un séparateur de faisceau polarisant (PBS) pour fournir un faisceau de sortie à partir de l'une ou de l'autre des sources ou de ces deux sources. Une lampe (12) est positionnée de manière adjacente à une face dont le plan est parallèle à l'axe optique du séparateur de faisceau et dont la sortie est réfléchie de manière interne. L'autre lampe (14) est positionnée de manière adjacente à une face arrière du séparateur de faisceau de telle sorte que sa sortie est la sortie du séparateur de faisceau. Chacun des faisceaux est polarisé dans une orientation unique. Un polariseur (22) est placé dans la trajectoire de sortie et est aligné pour transmettre une des orientations. Un dispositif de rotation à polarisation (18) est interposé entre le séparateur de faisceau (PBS) et le polariseur (22) et, par son orientation, détermine laquelle des entrées de lampe est transmise par le polariseur. Le dispositif de rotation (18) peut être mécanique, en comprenant une lame demi onde rotative, ou électronique en utilisant un dispositif retardateur à cristaux liquides (28, 28') qui est commandé par l'application d'un signal électrique. Le dispositif selon l'invention peut également servir de source d'éclairage «jour-nuit» si une lampe (12'') est une lampe de jour brillante et l'autre est une lampe de nuit moins brillante (14'') équipée d'un filtre à infrarouges. Ces lampes sont utilisées chacune à leur tour. Dans un autre mode de réalisation, des lampes de couleurs différentes peuvent être utilisées et ce dispositif peut transmettre la première couleur ou la deuxième couleur ou toute combinaison des première et deuxième couleurs.
EP00918456A 1999-08-06 2000-03-27 Lampes doubles a projection Withdrawn EP1410097A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US14757999P 1999-08-06 1999-08-06
US147579P 1999-08-06
PCT/US2000/008127 WO2001011414A1 (fr) 1999-08-06 2000-03-27 Lampes doubles a projection

Publications (1)

Publication Number Publication Date
EP1410097A1 true EP1410097A1 (fr) 2004-04-21

Family

ID=22522135

Family Applications (1)

Application Number Title Priority Date Filing Date
EP00918456A Withdrawn EP1410097A1 (fr) 1999-08-06 2000-03-27 Lampes doubles a projection

Country Status (2)

Country Link
EP (1) EP1410097A1 (fr)
WO (1) WO2001011414A1 (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TWI235263B (en) * 2002-05-14 2005-07-01 Sony Corp Illuminating optical system, image display unit and method of illuminating space modulation element
US7360900B2 (en) 2004-03-10 2008-04-22 Seiko Epson Corporation Illuminating apparatus, image display apparatus, and projector

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5042921A (en) * 1988-10-25 1991-08-27 Casio Computer Co., Ltd. Liquid crystal display apparatus
SG43161A1 (en) * 1990-07-24 1997-10-17 Thomson Brandt Gmbh Polarized light lighting device
EP0916221A2 (fr) * 1997-01-10 1999-05-19 Koninklijke Philips Electronics N.V. Systeme eclairant pour un dispositif projecteur d'image

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO0111414A1 *

Also Published As

Publication number Publication date
WO2001011414A1 (fr) 2001-02-15

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