Classifications

• • 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
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
  • G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light
  • G02B26/0816—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more reflecting elements
  • G02B26/0833—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more reflecting elements the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD
  • G02B26/0858—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more reflecting elements the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD the reflecting means being moved or deformed by piezoelectric means
• • 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
  • H04N5/7458—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 deformable mirrors, e.g. digital micromirror device [DMD]
• • 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

Definitions

• the present invention relates to an image display system; and, more particularly, to an image display system by using essentially thin- film actuated mirrors for generating an image from a television signal propagated through the air or cable.
• an optical projection system is known to be capable of providing a high quality display in a large scale.
• light from a lamp is uniformly illuminated onto an array of actuated mirrors such that each of the mirrors is coupled with a corresponding one of the actuators.
• the actuators may be made of an electrodisplacive material such as a piezoelectric or an electrostrictive material which deforms in response to an electric field applied thereto.
• the reflected light beam from each of the actuated mirrors is incident upon an aperture of a baffle.
• an electrical signal to each of the actuators By applying an electrical signal to each of the actuators, the relative position of each of the mirrors to the incident light beam is altered, thereby causing a deviation in the optical path of the reflected beam from each of the actuated mirrors.
• the optical path of each of the reflected beams is altered, the amount of light reflected from each of the mirrors which passes through the aperture is changed, thereby displaying an image.
• the modulator comprises a white light source having a collimation lens; a beam splitter for splitting the white light into three primary lights; a beam spreader for spreading the primary light beams; a non-reflective surface having apertures therein; a scanner for providing a horizontal sweep of the light beams onto a projection screen; a collimation lens; and a projection lens.
• the patent issued to Gregory Urn et al has certain deficiencies, however. For instance, there are problems associated with an inaccurate horizontal sweep caused by using the mechanically rotating scanner and an inaccurate control of reflection at the beam spreader resulting from using hinged actuated mirrors therein.
• Pat. No. 5,150,205 has been eliminated (see U.S. Pat. No. 5,560,697 issued on Oct. 1, 1997, and entitled “OPTICAL PROJECTION SYSTEM”) .
• the beam splitter has been replaced with an M x N pixel filter (see U.S. Pat. No. 5,612,814 issued on Mar. 18, 1997 and entitled “COMPACT SIZED OPTICAL PROJECTION SYSTEM”) .
• the hinge in the actuated mirror of the beam spreader has been eliminated and improved to have various alternatives (see U.S. Pat. No. 5,661,611 issued on Aug. 26, 1997 and entitled “THIN FILM ACTUATED MIRROR ARRAY AND METHOD FOR THE MANUFACTURE
• the actuated mirror in the beam spreader has been further improved to have a mirror arranged on top of an actuated structure in order to overcome the inaccurate control of reflection at the beam spreader (see U.S. Pat. No. 5,760,947 issued on Jun. 2, 1998 and entitled “THIN FILM ACTUATED MIRROR ARRAY FOR USE IN AN OPTICAL PROJECTION SYSTEM AND METHOD FOR THE MANUFACTURE THEREOF").
• a new driver circuit has been introduced to efficiently drive the actuated mirrors (see U.S. Pat. No. 5,793,348 issued on Aug. 11, 1998 and entitled “ACTUATED MIRROR ARRAY DRIVING CIRCUIT HAVING A DAC”) .
• an image display system capable of displaying an M x N number of pixels, wherein M and N are integers, respectively, comprising: a light source for emitting a white light; a total mirror for reflecting the white light at a predetermined angle; an optical filter for splitting the white light reflected from the total mirror into a trinity of primary light beams; a trinity of arrays of M x N actuated mirrors, including a first, a second and a third array of M x N actuated mirrors, each of the M x N actuated mirrors for generating optical pixel signals by reflecting the primary light beams impinging thereon, each of the actuated mirrors in the arrays being capable of changing the optical path of the primary light beams reflected therefrom; a projection stopper for partially transmitting the optical pixel signals; a driver circuit for controlling each actuated mirror based on an input image signal; and a projection screen for displaying the optical pixel signals passing through the projection stopper.
• Fig. 1 illustrates a schematic view of an image display system in accordance with a preferred embodiment of the present invention
• Fig. 2 describes a schematic view of an image display system in accordance with another preferred embodiment of the present invention
• Fig. 3 shows a side view of an array of actuated mirrors arranged on a substrate
• Figs. 4A to 4E demonstrate a cross sectional view of various exemplary make-ups of an actuated mirror
• Fig. 5 presents exemplary tracks of light beams before impinging on a projection stopper
• Figs. 6A to 6C exhibit various shapes of the projection stopper and exemplary configurations of primary lights impinging thereon;
• Fig. 7 represents exemplary tracks of light beams after impinging on the projection stopper
• Fig. 8 depicts a cooler for use in dissipating heat caused by a light source
• Fig. 9 provides a block diagram of a driver circuit in accordance with the present invention. MODES OF CARRYING OUT THE INVENTION
• FIG. 1 there is illustrated a schematic view of an image display system in accordance with an embodiment of the present invention comprising a light source 100, a source lens 102, a source stopper 104 provided with a light transmitting portion having a predetermined configuration and a light stopping portion, a total reflection mirror 106 including a reflective surface, optical filters 108, 110, field lenses 112, 114, 116, a trinity of arrays of M x N actuated mirrors 118, 120, 122, M and N being positive integers, respectively, a projection stopper 124 provided with a light transmitting portion having the predetermined configuration and a light stopping portion, a projection lens 126, a projection screen 128 and a driver circuit 130.
• a white light emanating from the light source 100 is focussed along a first optical path onto the light transmitting portion on the source stopper 104 via the source lens 102 located between the light source 100 and the source stopper 104, wherein the white light includes a first, a second and a third primary light beam, each of the primary light beams being one of the primary colors, i.e., red, green and blue.
• the source stopper 104 is used for shaping the white light from the light source 100 via the source lens 102 into a predetermined configuration by allowing a specific portion of the white light to pass through the light transmitting portion thereof.
• the white light from the source stopper 104 travels onto the reflective surfaces of the total reflection mirror 106.
• the reflective surface of the total reflection mirror 106 is in a facing relationship with the source stopper 104 and the field lenses 112, 114, 116.
• the white light reflected from the reflected surface of the total reflection mirror 106 impinges upon each of the optical filters made of dichroic mirrors 108, 110, i.e., a red color filter 108 and a blue color filter 110.
• the red color filter 108 reflects only red color component beam and transmits the other color component beams.
• the blue color filter 110 reflects only blue color component beam and transmits the other color component beams.
• Each of the component beams through the optical filters 108, 110 is uniformly illuminated onto the array of M x N actuated mirrors 118, 120, 122, respectively.
• Each of the actuated mirrors in the arrays 118, 120, 122 is capable of changing the optical path of each of the primary light beams reflected therefrom in response to an electric signal applied thereto.
• Each of the actuated mirrors in the arrays 118, 120, 122 corresponds to a pixel to be displaced on the projection screen 128.
• the reflected beams reflected from each of the reflective mirrors are focused at the projection stopper 124. Only a fraction of each beam impinged to the projection stopper 124 is transmitted through the projection stopper 124, the fraction ranging from 0% to 100% thereof.
• the array of M x N pixel filter 204 includes a plurality of sets of R pixel filter, G pixel filter and B pixel filter, each of the sets being duplicated both along a horizontal direction and a vertical direction.
• Each of the R, G and B pixel filter is capable of transmitting only one of the primary light beams onto each of the actuated mirrors 206.
• Each of the R, G and B pixel filter includes a dichroic coat, made of a dielectric material, e.g., MgF 2 .
• Each of the actuated mirrors in the array 206 reflects one of the primary beams from the array of the pixel filter 204, thereby producing a packet of reflected primary beams travelling along an optical path, i.e., a third optical path, different from that of the primary light beams from the array of M x N pixel filter 204.
• the embodiment shown in Fig. 2 is of a reduced size and is structurally simple, requiring a less number of components than the one shown in Fig. 1. This is achieved by incorporating therein an array of M x N pixel filter 204, thereby eliminating the pair of dichroic mirrors 108, 110, a pair of field lenses 112, 114 and a pair of arrays of actuated mirrors 118, 120 in the embodiment of Fig. 1. Further detailed structure, operation and modifications of the image display system of Fig. 2 is disclosed in U.S. Pat. No. 5,612,814 issued on Mar. 18, 1997, entitled “COMPACT SIZED OPTICAL PROJECTION SYSTEM, " which is herein incorporated by reference therefrom as if fully set forth at length herein.
• Fig. 3 shows a side view of the array of M x N actuated mirrors arranged on a substrate 302.
• the array of M x N actuated mirrors 300 includes a substrate 302, M x N number of actuated mirrors 304 and pedestals 306 uniformly arranged on the upper surface of the substrate 302.
• Figs. 4A to 4E illustrate a cross sectional view of various exemplary make-ups of an actuated mirror.
• Fig. 4A represents a detailed cross sectional view of an active matrix including a segment of the substrate 426 and an actuated mirror 400, wherein each of the actuated mirrors 400 is provided with a top and a bottom surfaces 412, 418, respectively, a proximal and a distal ends 408 and 410, respectively, and further includes at least a thin film layer 404 of a motion inducing material 404, a first and a second electrodes 402 and 406, respectively, of a specific thickness, made of, e.g., a metal such as gold (Au) or silver (Ag) , the first electrode 402 having a top surface 412 reflecting the primary lights.
• a metal such as gold (Au) or silver (Ag)
• the first electrode 402 is placed on an inner top surface 416 of the motion-inducing thin film layer 404 and the second electrode 406 on an inner bottom surface 418 thereof.
• the motion- inducing thin film layer 404 is made of a piezoelectric ceramic, an electrostrictive ceramic, a magnetrostrictive ceramic or a piezoelectric polymer. In the case when the motion-inducing thin film layer 404 is made of a piezoelectric ceramic or a piezoelectric polymer, it must be poled.
• Each of the M x N pedestals 422 is used for holding each of the actuated mirrors 400 in place and also for electrically connecting the second electrode 402 in each of the actuated mirrors 400 with the corresponding connecting terminal 424 on the substrate 426 by being provided with a conduit 420 made of an electrically conductive material, e.g., a metal.
• An electrical field is applied across the motion- inducing thin film layer 404 between the first and the second electrodes 402, 406, in each of the actuated mirrors 400.
• the application of such an electric field will cause a deformation of the motion- inducing layer 404, hence the actuated mirror 400, and hence the top surface 412 thereof.
• a mirror- topped thin film actuated mirrors with a mirror topped thereon.
• the mirror-topped thin film actuated mirrors further includes a mirror layer 450 for reflecting lights mounted on top surface 412 of the thin film actuated mirrors shown in Figs. 4A to 4D and a supporting layer 452.
• the mirror layer 450 can be applied to any one of the thin film actuated mirrors shown in Figs. 4A to 4D .
• the mirror layer 450 is capable of providing a linearity in bending and tilting of the actuated mirrors, which in turn gives accuracy in reflecting the primary lights.
• FIG. 5 there is presented exemplary tracks of light beams before impinging on the projection stopper 124.
• Light beams shown with solid lines represent the light paths before impinging the arrays of the actuated mirrors and light beams represented with dotted lines are for the light paths after impinging the arrays of the actuated mirrors.
• Light beams 502 represent the lights generated from the light source 100; light beams 504 represent the lights reflected at the total mirror 106; light beams 506 represent the lights that have been transmitted through the red color filter 108, i.e., the light beams 506 being a light beam including green and blue color beams; light beams 508 represent the lights that have been transmitted through the blue color filter 110, i.e., the light beams 508 being a light beam including green color beams; and light beams 510 represent portions of the light beams 504 that have been reflected from the red color filter 108, i.e., the light beams 510 being a light beam including red color beams; and light beams 512 represent portions of light beams 506 reflected at the blue color filter 110, i.e., the blue color beam.
• the arrangement of the optical filters may be interchanged.
• Light beams 520 represent light beams reflected at the array of actuated mirrors 122; light beams 522 represent light beams reflected at the array of actuated mirrors 120; light beams 524 represent light beams reflected at the array of actuated mirrors 118; light beams 526 represent parts of light beams 522 that have been reflected at the optical filter 110; light beams 528 represent parts of light beams 524 that have been reflected at the optical filter 108.
• the total mirror 106 is arranged in such a manner that the light beams 520, 526 and 528 may be focussed on the projection stopper 124.
• the total mirror 106 should be so arranged that it will not be on the way of the light paths of the light beams 520, 526 and 528.
• Figs. 6A to 6C there are plotted various shapes of the projection stopper 124 or 602, 612, 622 and exemplary configurations of the primary lights impinging thereon, i.e., a circle type 600, a rectangular type 610 and an edge type 620, respectively.
• etched parts present the light blocking portion of the projection stopper 124 and non-etched parts present the light transmitting portion thereof.
• 627, 628 represents an illumination caused by one thin film actuated mirror of the arrays of actuated mirrors.
• the light transmitting portion 604 is the circle type.
• the light beams having been reflected at the arrays of actuated mirrors impinge the projection stopper 124.
• the illumination is partially blocked; in case of "B”, the entire illumination passes through the projection stopper 124; and in case of "C”, the illumination is entirely blocked by the projection stopper 124.
• the illumination is partially blocked; in case of "B”, the entire illumination passes through the projection stopper; and in case of "C”, the illumination is entirely blocked by the projection stopper.
• any stoppers which are capable of partially block the impinging light can be used.
• the quantity of the illumination passing through the projection stoppers 600, 610, 620 corresponds to the intensity of light at a pixel of the projection screen 128.
• the illumination intensity of the light at the pixel of the projection screen 128 is controlled.
• Fig. 7 represents exemplary tracks of light beams after impinging into the projection stopper.
• the light beams reflected at each of the arrays of actuated mirrors are focussed near the light transmitting portion of the projection stopper 124.
• the light beams that have passed through the projection stopper 124 should be fanned out.
• the projection lens 126 fans out the light beams, and, then, properly arranged mirrors 700, 702 reflect the light beams after passing through the projection lens 126 to make the light beams accurately fit onto the projection screen 128.
• Light beams 710, 712, 714 are sequentially fanned out as they are reflected from the mirrors 700, 702.
• the number of the mirrors, e.g., 700, 702 is variable depending on the size of the projection screen 128 and the length of the paths of the light beams transmitted from the projection stopper 124.
• the light source 100 radiates not only optical energy but also thermal energy.
• the thermal energy heats up the image display system.
• the arrays of actuated mirrors are mostly heated up by the thermal energy. Temperature increase in the arrays of actuated mirrors may cause malfunction or failure.
• Fig. 8 depicts a cooler for use in dissipating heat generated in the system, wherein an electric fan 800 is used in cooling the arrays of actuated mirrors.
• a heat -radiator which is normally used in cooling semiconductor devices may be used.
• the driver circuit 130 Fig.
• each element in the arrays of actuated mirrors includes a plurality of TFTs (Thin Film Transistors) 970 which are arranged as crossovers of data lines 974 and select lines 972.
• TFTs Thin Film Transistors
• select lines 972 As each of the select lines 972 is sequentially selected, a data signal is applied as a voltage signal to a signal line 974 which is individually associated with a row of thin film actuated mirrors to thereby produce a horizontal video line of an image on the display.
• the driver circuit provided in Fig. 9 further includes a frame memory 910 and five modular package ICs 920, 930, 940, 950, 960 having 128-channel of a substantially identical construction.
• a video signal in the form of a digitized data signal is fed to the frame memory 910 for the storage thereof through an input terminal.
• the video signal comprises a plurality of horizontal line video signals being scanned in accordance with a scanning pulse.
• Each of the digital signals is divided into N number, i.e., 640, of digital signals, each of the divided digital signals having 8 -bit data.
• the stored digital data signals are sequentially provided to the package ICs 920, 930, 940, 950, 960 from the frame memory 910.
• the above-described image display system is more accurate than the system using the mechanical scanner since it employs the array of actuated mirrors which is a static pixel image generator. Further, the inventive image display system is capable of providing images of higher-definition since each of the actuated mirrors is more efficient in operation than the prior art counterpart of a clamped type. In addition, the inventive image display system is more reliable and feasible than the prior art counterpart since an avoidable heat accumulation can be reduced by the cooler.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Engineering & Computer Science (AREA)
• Multimedia (AREA)
• Signal Processing (AREA)
• Mechanical Light Control Or Optical Switches (AREA)

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• 1998
  • 1998-12-22 AU AU16935/99A patent/AU754538B2/en not_active Ceased
  • 1998-12-22 EP EP98961659A patent/EP1064794A1/de not_active Withdrawn
  • 1998-12-22 CA CA002321760A patent/CA2321760A1/en not_active Abandoned
  • 1998-12-22 WO PCT/KR1998/000453 patent/WO2000038433A1/en not_active Application Discontinuation

Non-Patent Citations (1)

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