Classifications

• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
  • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
  • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
  • G09G3/3406—Control of illumination source
  • G09G3/3413—Details of control of colour illumination sources
• • 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
  • G02B27/10—Beam splitting or combining systems
  • G02B27/14—Beam splitting or combining systems operating by reflection only
  • G02B27/145—Beam splitting or combining systems operating by reflection only having sequential partially reflecting surfaces
• • 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
• • 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
  • H04N9/3114—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 one colour at a time
• • 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
• • 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]
  • H04N9/3197—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM] using light modulating optical valves
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N9/00—Details of colour television systems
  • H04N9/64—Circuits for processing colour signals
  • H04N9/73—Colour balance circuits, e.g. white balance circuits or colour temperature control
• • 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
  • G02F1/133621—Illuminating devices providing coloured light
  • G02F1/133622—Colour sequential illumination
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G2310/00—Command of the display device
  • G09G2310/02—Addressing, scanning or driving the display screen or processing steps related thereto
  • G09G2310/0235—Field-sequential colour display

Definitions

• This invention relates to display systems, and more particularly relates to display systems incorporating light-emitting diode (LED) light sources employing a combination of LEDs of different wavelengths.
• LED light-emitting diode
• the increasing availability of LEDs of various colors (eg., red, green and blue) and increasing lumen output has created interest in producing commercial products for lighting and display applications.
• LEDs are attractive for such applications due to their relatively small size, low power consumption and their ability to switch on and off at a frame rate sufficiently fast to cause the viewer to integrate the separate color images into a full color image.
• LEDs attractive for other applications.
• the small size of LEDs makes them attractive for use in systems having a limited etendue, such as projection systems employing one or more small liquid crystal light modulator panels.
• the invention is based on the realization that individual LEDs have output beams characterized by relatively narrow spectra (eg., about 20 nm) and can be produced to have any desired peak wavelength within a wide range, and that the output beams of LEDs of different but closely spaced peak wavelengths (spacing of 1 nm or more) can be combined into a beam of greater lumen output with little or no increase in etendue.
• a combination of two or more of such LEDs is referred to as an "LED set".
• a light source for a display system comprising at least one LED set, and also comprising means such as a dichroic filter to combine the separate output beams from the individual LEDs of the set into a beam of greater lumen output with little or no increase in etendue.
• the separate output beams may be produced either by individual LEDs or by clusters or arrays of LEDs having approximately the same peak wavelength of emission.
• these individual LEDs, LED clusters and arrays will be referred to collectively as “LED beam sources” or “LED sources”.
• the LED set is combined with one or more LED beam sources and/or LED sets of different colors to produce a combined light output dependent on the wavelengths of the component colors.
• Control circuitry may be provided to change the power levels of the colors and/or to switch the colors on and off periodically, in order to vary the color and/or brightness of the display.
• a display system incorporating such a light source, comprising separate primary color channels of red, green and blue beams, one or more of which color channels is produced by an LED set, are modulated by one or more light modulator panels to produce a color display.
• the different peak wavelengths in each LED set should be separated from one another by at least 1 nm, and preferably by about 20nm, with greater separations being determined by desired spectral characteristics of the combined beams.
• the green channel could be composed of a set of two LED beam sources, one source composed of one or more 530 + 10 nm LEDs and the other source composed of one or more 550 + 10 nm LEDs.
• the red channel could be composed for example, of a 595 + 10 nm source and a 615 + 10 nm source, while the blue channel could be composed for example, of a 450 + 10 nm source and a 470 + 10 nm source.
• Fig. 1 is a diagram of an LED set of the invention, showing dichroic mixing of two red LED source beams into a single red beam;
• Fig. 2 is a diagram of an LED source comprising a cluster of individual LEDs;
• Fig. 3 is a diagram of a light source of the invention including a green LED set
• Fig. 4 is a diagram of a color projection display system incorporating a light source of the invention.
• Red LED sources 11 and 12 each comprise a single LED 13,14 located within a reflector 15,16 and emitting a source beam at a different peak wavelength, 595 and 615 nm, respectively.
• the source beams are each directed at an incident angle of 45 degrees onto opposite sides of dichroic filter 19, supported within optical element 18.
• Filter 19 is designed to transmit the 595 nm beam and to reflect the 615 nm beam.
• the transmitted beam and the reflected beam emerge from optical element 18 along a common path as a combined beam 2 of increased lumen output but unchanged etendue.
• LED sources 11 and 12 could alternately each comprise a cluster or array of individual LEDs, as shown schematically in Fig. 2.
• LED source 20 includes an array of individual LED packages 23. Each package includes an LED 22 carried on a substrate 24, encapsulated in a dome-shaped element 26, and fitted into lens 28.
• Collector lens 30 directs light from the array to a target 32, such as an electro-optic light modulator panel.
• the combined beam may be employed as a standard single color beam of broader spectrum, and can be subsequently mixed or combined with other color beams for display purposes.
• the present state of LED technology does not allow the production of a green LED of sufficient lumen output, so that the full lumen output of the red and blue LEDs, which are more closely balanced, cannot be utilized without upsetting the desired color balance.
• the lumen output of the green beam is nearly doubled, allowing the red and blue beams to be driven to higher lumen outputes also, resulting in a near doubling of the combined white light output.
• Such a light source is shown diagrammatically in Fig. 3, in which green LED sources LI and L2, having beams Gl and G2, whose peak wavelengths are 530 + 10 and 550 + 10 nm, respectively, combined into a single beam by dichroic mirror Ml .
• This combined green beam is then combined with a red beam R from LED source L3 by dichroic mirror M2.
• the combined red and green beams are then combined with blue beam B from source L4 by dichroic mirror M3, to produce a white light output beam W.
• An exemplary three-panel color projection display system of the invention is shown diagrammatically in Fig. 4.
• Green beams Gl and G2 from sources LI and L2, respectively, are combined into a single beam by dichroic mirror Ml.
• red beams Rl and R2 from sources L3 and L4 are combined by mirror M2.
• the green and red beams are then directed along a common axis by dichroic mirror M3 to light modulator panel P and thence to projection lens PL.
• Blue beams Bl and B2 from sources L5 and L6 are combined by dichroic mirror M4, and then directed along the common axis of the red and green beams by dichroic mirror M5.
• the red, green and blue beams are modulated separately by light modulator panel P in accordance with separate display signals.
• the panel P is addressed with the separate primary color components of the video signal at the video frame rate eg., 60 Hz, and the LED sources LI through L6 are synchronously pulsed on and off in a manner to illuminate panel P with the color corresponding to that of the primary color component being addressed.
• Panel P is preferably a liquid crystal display device.
• the actual order of the dichroic mirrors need not be that shown.
• the invention allows the beams to be mixed in any sequence consistent with good filter and optical path design criteria.

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• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Multimedia (AREA)
• Signal Processing (AREA)
• General Physics & Mathematics (AREA)
• Nonlinear Science (AREA)
• Optics & Photonics (AREA)
• Mathematical Physics (AREA)
• Chemical & Material Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Computer Hardware Design (AREA)
• Theoretical Computer Science (AREA)
• Projection Apparatus (AREA)
• Liquid Crystal (AREA)

Applications Claiming Priority (3)

Publications (1)

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• 2000
  • 2000-11-23 JP JP2001543717A patent/JP2003516558A/ja not_active Abandoned
  • 2000-11-23 KR KR1020017009932A patent/KR100817786B1/ko not_active IP Right Cessation
  • 2000-11-23 WO PCT/EP2000/011651 patent/WO2001043113A1/en active Application Filing
  • 2000-11-23 EP EP00979618A patent/EP1159728A1/de not_active Withdrawn

Non-Patent Citations (1)

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