WO1996013943A1 - Elimination du trou dans la lumiere emise par une lampe a reflecteur - Google Patents

Elimination du trou dans la lumiere emise par une lampe a reflecteur Download PDF

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Publication number
WO1996013943A1
WO1996013943A1 PCT/US1995/014109 US9514109W WO9613943A1 WO 1996013943 A1 WO1996013943 A1 WO 1996013943A1 US 9514109 W US9514109 W US 9514109W WO 9613943 A1 WO9613943 A1 WO 9613943A1
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WO
WIPO (PCT)
Prior art keywords
light
lens
lamp
reflector
hole
Prior art date
Application number
PCT/US1995/014109
Other languages
English (en)
Inventor
Philip Jones
Akira Tomita
Original Assignee
Raychem Corporation
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 Raychem Corporation filed Critical Raychem Corporation
Publication of WO1996013943A1 publication Critical patent/WO1996013943A1/fr

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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
    • G02B27/09—Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for
    • G02B27/0927—Systems for changing the beam intensity distribution, e.g. Gaussian to top-hat
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
    • F21V13/00—Producing particular characteristics or distribution of the light emitted by means of a combination of elements specified in two or more of main groups F21V1/00 - F21V11/00
    • F21V13/12—Combinations of only three kinds of elements
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B19/00—Condensers, e.g. light collectors or similar non-imaging optics
    • G02B19/0004—Condensers, e.g. light collectors or similar non-imaging optics characterised by the optical means employed
    • G02B19/0028—Condensers, e.g. light collectors or similar non-imaging optics characterised by the optical means employed refractive and reflective surfaces, e.g. non-imaging catadioptric systems
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B19/00—Condensers, e.g. light collectors or similar non-imaging optics
    • G02B19/0033—Condensers, e.g. light collectors or similar non-imaging optics characterised by the use
    • G02B19/0047—Condensers, e.g. light collectors or similar non-imaging optics characterised by the use for use with a light source
    • 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
    • G02B27/09—Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for
    • G02B27/0938—Using specific optical elements
    • G02B27/095—Refractive optical elements
    • G02B27/0972—Prisms
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/001—Axicons, waxicons, reflaxicons
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B21/00—Projectors or projection-type viewers; Accessories therefor
    • G03B21/14—Details
    • G03B21/20—Lamp housings
    • 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
    • H04N9/3105—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM] using two-dimensional electronic spatial light modulators for displaying all colours simultaneously, e.g. by using two or more electronic spatial light modulators
    • 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

Definitions

  • This invention relates generally to a system for eliminating a hole in light projected from a light source which includes a reflecting element, and more particularly to a lens or mirror system for eliminating such hole, particularly when the reflecting element is a parabolic reflector.
  • a projection display In a projection display, light from a light source has an image imparted to it and is projected onto a screen for viewing.
  • the display may be a front projection one, in which the projection mechanism is positioned on the same side of the screen as the viewer, or a rear projection one, in which the projection mechanism is positioned on the side of the screen away from the viewer. In either case, a collimated light beam of uniform brightness is required to achieve an image of uniform brightness.
  • Beams of red, green and blue light may be combined and projected to provide a colored display.
  • the red, green and blue light beams may be generated from separate red, green, and blue light sources.
  • using a single white light source whose light is separated into red, green and blue beams is a preferred design, since it is more economical to use a single light source and true white is assured when the beams are combined.
  • the separation (and subsequent recombination) may be effected by dichroic mirrors (e.g., Williams et al., WO 90/05429 (1990); Tanaka et al., US 5,164,821 (1992)).
  • a conventional light source 20 including parabolic reflector 22 and arc lamp 24 is shown schematically in FIG. la.
  • Arc lamp 24 is powered by power source 34 which is connected by first wire 36 to left lead 32 of arc lamp 24.
  • Power source 34 is also connected via second wire 37, connector socket 38, and internal lamp wire 39 to right lead 33 of arc lamp 24.
  • Right lead 33 is encased in insulator 53, on which is mounted light shield 26, typically about 10 mm in diameter.
  • Light shield 26 intercepts all light that would otherwise exit light source 20 without striking parabolic reflector 22, i.e., a projection from emission gap 30 of arc lamp 24 past an edge of light shield 26 falls on parabolic reflector 22.
  • Left lead 32 is encased in stiff insulating tube 52 which supports arc lamp 24 such that gap 30 between left lead 32 and right lead 33 is located at the focus of parabolic reflector 22, i.e., at the focus of a parabolic cross-section thereof. Therefore, all light rays emitted from gap 30 and reflected off parabolic reflector 22 travel parallel to axis of symmetry 42 of parabolic reflector 22. Because light source 20 is cylindrically symmetric about axis of symmetry 42 (except for wire 39 which has only a small effect on beam 47), beam 47 produced by light source 20 is also cylindrically symmetric about axis of symmetry 42, as shown in the cross-section thereof in FIG. lb.
  • FIG. la The paths of four light rays 40a-40d are traced in FIG. la. Their positions within beam 47 are shown in FIG. lb. (Light rays within the beam are generally referenced with the numeral "40," the hole in the beam has the reference numeral "45,” and the entirety of the beam, i.e., the light rays 40 and the hole 45, has the reference numeral "47.")
  • a first ray 40a passes close to the upper edge of light shield 26, strikes parabolic reflector 22, and exits parallel to axis of symmetry 42.
  • Ray 40a lies at the outer boundary of beam 47, as shown in FIG. lb, since light rays cannot strike parabolic reflector 22 any farther from apex 23 due to light shield 26.
  • Another ray 40d strikes parabolic reflector 22 closer to apex 23, is reflected parallel to axis of symmetry 42, and passes just outside of light shield 26. As shown in FIG. lb, ray 40d lies at the outer boundary of a hole 45 in beam 47. Rays which strike parabolic reflector 22 closer to apex 23 than ray 40d are reflected back parallel to axis of symmetry 42, and strike arc lamp 24 and light shield 26, thereby creating hole 45 in the beam. Beam 47 from light source 20 is therefore a column of light with a central hole 45 having a radius equal to that of light shield 26, with innermost ray 40d located at the outside of the hole 45.
  • An object of the present invention is therefore to provide a light source with a beam having a uniform intensity. Another object of the present invention is to provide a light source with a highly collimated beam. Another object of the present invention is to provide a light source with a large f number. Another object of the present invention is to provide an electronically modulated light scattering display with high contrast. Another object of the present invention is to provide a light source which uses a reflector, particularly a parabolic reflector. Another object of the present invention is to provide a light source which uses a prism lens for elminating the central hole. Another object of the present invention is to provide a light source which uses a mirror system for eliminating the central hole.
  • the present invention is directed to a lamp for providing a collimated beam.
  • the light source is mounted on a reflector, and has a shield to intercept light which would otherwise escape the lamp without reflecting from the reflector.
  • the shield produces a hole in the reflected light, and a light displacement system (which can be a lens or mirror system) is used to displace light towards the center of the hole by a distance equal to the width of the hole, thereby eliminating the hole in the beam.
  • the light is displaced by a distance approximatly equal to the radius of the hole.
  • FIG. la is a cross-sectional view of a conventional lamp.
  • FIG. lb is a cross-section of the beam produced by such lamp, showing a hole in the beam.
  • FIG. 2a is a cross-sectional view of a lamp according to the present invention, which includes a conical prism lens.
  • FIG. 2b is a cross-section of the beam produced by the lamp of FIG. 2a.
  • FIG. 2c is a cross-sectional view of a lens which is the Fresnel equivalent of the conical prism lens of FIG. 2a.
  • FIG. 2d is a cross-section of the beam produced by the lens of FIG. 2c.
  • FIG. 3 shows a perspective view of the conical prism lens of FIG. 2a.
  • FIG. 5 is a schematic view of a transmissive liquid crystal projector using the conical prism of the present invention.
  • FIG. 6 is a schematic view of a reflective liquid crystal projector using the conical prism of the present invention.
  • FIG. 7a shows path traces of two pairs of light rays which emanate from a light source with a separation angle of ⁇ , reflect from the parabolic reflector, and pass through a prism lens having a corrective curvature for providing a uniform light intensity.
  • FIG. 7b is a view from the front of the parabolic reflector of path traces of two pairs of light rays, the rays in each pair emanating at an azimuthal separation angle ⁇ .
  • FIG. 7c is a plot of light intensity versus radius for the light reflected from the parabolic reflector of FIG. 7a.
  • FIG. 7d is a plot of light intensity versus radius for light transmitted through the prism lens with a corrective curvature shown in FIG. 7a.
  • FIG. 7e is a diagram illustrating the effective thickness h' of a prism lens with corrective curvature.
  • FIG. 8a is a cross-sectional view of a lamp where a bi-concave lens is used to collimate the light from an elliptical reflector prior to incidence on a conical prism.
  • FIG. 8b is a cross-sectional view of a lamp where the order of the conical prism lens and the elliptical reflector in FIG. 8a is reversed.
  • FIG. 9a shows an embodiment of the invention in which a mirror system is used to eliminate the central hole.
  • FIG. 9b shows a construction for the mirror system of Fig. 9a.
  • FIG. 10 shows another embodiment in which a mirror system is used to eliminate the central hole.
  • FIG. 2a shows a lamp 120 for projection of a highly collimated beam with no central hole.
  • Lamp 120 includes parabolic reflector 122 and arc lamp 124.
  • Arc lamp 124 is powered by power source 134 which is connected by first wire 136 to left lead 132 of arc lamp 124.
  • Power source 134 is also connected via second wire 137, connector socket 138, and internal lamp wire 139 to right lead 133 of arc lamp 124.
  • Right lead 133 is encased in insulator 153, on which is mounted light shield 126 which prevents light from exiting lamp 120 without striking parabolic reflector 122, i.e., a projection from emission gap 130 of the arc lamp 124 past an edge of light shield 126 falls on parabolic reflector 122.
  • Left lead 132 is encased in stiff insulating tube 152 which supports arc lamp 124 such that gap 130 between left lead 132 and right lead 133 is located at the focus of parabolic reflector 122, i.e., at the focus of the parabolic cross-sections thereof. Therefore, all light rays leaving gap 130 and reflecting off parabolic reflector 122 travel parallel to axis of symmetry 142 of parabolic reflector 122.
  • gap 130 should be as small as practicable, e.g., approximately 1 mm in length. Because all optical com ⁇ ponents of lamp 120 are cylindrically symmetric about axis of symmetry 142 (except for wire 139 which has only a small effect), beam 140 produced by lamp 120 is also cylindrically symmetric about axis of symmetry 142.
  • Conical prism lens 150 After reflecting off parabolic reflector 122, rays 140 travel parallel to axis of symmetry 142 until they strike conical prism lens 150 (which is shown in a perspective view in FIG. 3).
  • Conical prism lens 150 has a conical exterior surface 151 and a conical interior surface 152.
  • the angle ⁇ of conical exterior surface 151 from the radial direction i.e., ⁇ is the angle between the normal vector to the surface of the cone and axis of symmetry 142, and interior angle of apex 154 of lens 150 is 180° - 2 * ⁇ ) is equal to that of interior surface 152 from radial so that conical prism lens 150 has a constant thickness h. As shown in FIG.
  • each ray 140 strikes lens conical prism 150 at an angle ⁇ from the normal of conical exterior surface 151. Rays 140 are refracted by the larger index of refraction n 2 of conical prism lens 150 to produce rays 140' which pass therethrough at an angle ⁇ from the normal, where according to Snell's law: n
  • sin ⁇ n 2 sin ⁇ , and n[ is the index of refraction of the surrounding medium, which will usually be air and thus is close to unity.
  • light ray 140d strikes parabolic reflector 122 near apex 123, is reflected parallel to axis of symmetry 142, passes just outside of light shield 126, and is refracted as it enters and exits conical prism lens 150 such that exiting ray 140d" is displaced radially inwards by a distance r from incident ray 140d.
  • Thickness h and index of refraction n of lens 150 are chosen such that the radial displacement d of the ray 140 ⁇ V140d" is equal to the radius r of the projection of light shield 126 along axis of symmetry 142. Therefore, ray 140d" travels along axis of symmetry 142, as shown in FIG. 2a, and is located at the center of output beam 140, as shown in FIG. 2b.
  • Another light ray 140a is emitted from gap 130 of arc lamp 124, passes near the edge of light shield 126, is reflected from parabolic reflector 122, and travels parallel to axis of symmetry 142.
  • Ray 140a is refracted by conical prism lens 150 to produce ray 140a' which travels therethrough.
  • ray 140a' is again refracted to produce ray 140a" which travels parallel to axis of symmetry 142 and is also radially displaced inwards by a distance r.
  • ray 140a' lies at the outer boundary of beam 140, since light rays cannot strike parabolic reflector 122 any farther from apex 123 of parabolic reflector 122 due to light shield 126.
  • FIGS. 2a and 2b Also shown in FIGS. 2a and 2b are light rays 140b and 140c which exit gap 130 at angles between that of previously discussed rays 140a and 140d. They too strike parabolic reflector 122, are reflected parallel to axis of symmetry 142, are refracted on entering and leaving conical prism lens 150, and exit traveling parallel to axis of symmetry 142. Beam 140 is therefore a column of light with no central hole, suitable for uses requiring a uniform illumination. It should be noted that conical prism lens 150 produces a non-conformal mapping since a multiplicity of points on the edge of the hole of FIG. lb are mapped to the central point 140d"/142 of FIG. 2b.
  • Fresnel lens 250 shown in cross-section in FIG. 2c is the Fresnel equivalent of conical prism lens 150 of FIG. 2a.
  • Fresnel lens 250 is formed by slicing conical prism lens 150 of FIG. 2a into annular sections and aligning these sections substantially in a single plane.
  • FIG. 2d shows the top portions of five complete sections 261-265 and one partial section 266 in cross-section.
  • Fresnel lens 250 has cylindrical symmetry about optical axis 242, and front and back faces 251 and 252, respectively, of each section 261-266 is sloped at an angle ⁇ from the radial direction.
  • Each ray 240 strikes the conical element at an angle ⁇ from the normal of the front conical surface 251.
  • the thickness h and the index of refraction n of Fresnel lens 250 is chosen such that the radial displacement d of rays passing through central section 261 is equal to the radius r of the projection of light shield 126 of FIG. 2a along the axis of symmetry 242, thereby removing the hole from the beam 240.
  • this relationship for d does not hold when a ray enters Fresnel lens 250 in one section and exits in another section. For instance, ray 242 enters in the third section 263 and exits in the second section 262 as ray 242".
  • ray 242 effectively experiences a lens of a greater thickness than h, and is displaced by a greater distance than that given in the expression above.
  • adjacent ray 241 enters the lens in third section 263 and also exits from the third section 263 as ray 241". Therefore, as shown in FIG. 2d, from the uniform brightness beam 240 incident on the Fresnel lens 250, Fresnel lens 250 produces a beam 240" having concentric circular dark bands 270, 271, 272, etc.
  • Each dark band 270, 271, 272, etc. has an outer radius equal to the radius of the boundary between sections 261, 262, 263, etc., of Fresnel lens 250.
  • a transmissive projector system 380 using lamp 120 is shown schematically in FIG.
  • Arc lamp 124 is located at the focus of parabolic reflector 122, so that light emitted therefrom is reflected to form a beam 140 traveling parallel to axis of symmetry 142.
  • Light shield 126 intercepts light which would otherwise not be reflected by parabolic reflector 122, thereby insuring that all light 140 emanating from the arc lamp 124/reflector 122 system is collimated.
  • collimated light 140 from parabolic reflector 122 has a central hole, as shown in FIG. lb, since light shield 126 also intercepts light traveling along a path close to axis of symmetry 142.
  • Conical prism lens 150 acts to shift all rays of reflected beam 140 closer to axis of symmetry 142 to produce a beam 140" that does not have a central hole.
  • Arc lamp 124, parabolic reflector 122 and conical prism lens 150 produce collimated white light having red, blue and green components r, g and b, respectively.
  • the light is directed to a top left dichroic filter mirror 385 which reflects red component r to- wards a lower left mirror 388, but allows green component g and blue component b to pass through to a top center dichroic filter mirror 386.
  • Top center dichroic filter mirror 386 allows blue component b to pass through to a blue-component image forming element 393, and reflects green component g towards a green-component image forming element 392.
  • Red component r is reflected from a mirror 388 to a red-component image forming element 391.
  • Image forming elements 391, 392 and 393 may be made of encapsulated liquid crystal material, as is described in U.S. Patent Nos. 4,435,047 (1984), 4,606,61 1 (1986), 4,616,903 (1986), and 4,707,080 (1987), all to Fergason; U.S. Patent Nos. 5,075,789 (1991), 5,136,403 (1992), 5,138,472 (1992), and 5,175,637 (1992), all to the present inventor as the sole inventor or a coinventor; U.S. Patent Nos. 4,671,618 (1987), 4,673,255 (1987), 4,685,771 (1987), 4,688,900 (1987), all assigned to Kent State University; U.S. Patent Nos.
  • image forming elements 391, 392 and 393 have pixels (representative pixels being identified in the figure by reference numerals 391a, 392a, and 393a) which are independently switchable between light transmitting and light reflecting states by computerized control system 399 connected to the image forming elements 391, 392 and 393 via lines 396, 397 and 398, respectively.
  • Image-forming elements 391, 392, and 393 also may be made with twisted nematic liquid crystal cells, as is well known in the art. Then, the red, green and blue images from red-, green-, and blue-component image forming elements 391, 392 and 393 are combined to provide a colored image.
  • a bottom center dichroic filter mirror 389 combines red component r and green component g by allowing red component r to pass through and reflecting green component g. Then red component r and green component g are combined with blue component b by a bottom right dichroic filter mirror 390 which allows red component r and green component g to pass through, and reflects blue component b, thereby providing a full-color image.
  • the full-color image is incident upon lens 94 which focuses the image on a screen 395.
  • a reflective projector system 400 using lamp 120 is shown schematically in FIG. 6.
  • Beam 140" from lamp 120 is focused by field lens 410 onto mirror 415 which directs focused light 440 to dichroic cube 420.
  • the operation of dichroic cubes is described in detail in Sonehara, U.S. Pat. No. 5,098,183 (1992), Kurematsu et al., U.S. Pat. No. 5,170,194 (1992), Planner et al., U.S. Pat. No. 5,172,222 (1992), and copending, commonly assigned allowed application of Jones, Serial No. 08/074570, filed Jun. 7, 1993; and these disclosures are incorporated herein by reference.
  • dichroic cube 420 has three liquid crystal display cells 422r, 422b, and 422g (referred to collectively by reference numeral 422) mounted on faces of the cubes.
  • Display cells 422 have pixels (not shown) which may be separately controlled by a computerized control means (not shown) so as to reflect an image.
  • Dichroic cube 420 uses dichroic mirrors to separate incident white light 441 into red, blue and green components which are directed to red, blue and green display cells 422r, 422b, and 422g, respectively.
  • the red, blue and green images from display cells 422r, 422b and 422g are then recombined by the dichroic mirrors and a beam 443 having the full-color image exits dichroic cube 420.
  • Beam 443 is focused by projection lens system 430 to provide imaged beam 445 which is projected onto screen 450 for viewing.
  • Projectors 380 and 400 may be either of the front projection or rear projection type.
  • conical prism 150 of FIGS. 2a and 2c has the desired effect of eliminating the hole in the beam 140 produced by light shield 126, the intensity of light diminishes with radial displacement. This is illustrated by FIG. 7a which shows path traces of a first pair of rays 710a and 710b (referred to collectively by reference numeral 710) and a second pair of rays 720a and 720b (referred to collectively by reference numeral 720).
  • each pair 710 and 720 are separated by the same angle ⁇ as they emanate from gap 130.
  • the pair of rays 710 which strike parabolic reflector 122 closer to apex 123 and are reflected closer to axis of symmetry 142 have a smaller radial separation ⁇ r 2 than the radial separation ⁇ ri of the pair of rays 720 which strike parabolic reflector 122 farther from apex 123 and are reflected farther from axis of symmetry 142.
  • a similar effect occurs azimuthally, as is diagramatically illustrated in the front view of parabolic reflector 122 of FIG. 7b.
  • a first pair of light rays 730 emanating from gap 130 with an azimuthal separation angle ⁇ are separated by a smaller distance ⁇ r 3 when they reflect from parabolic reflector 122 at a point near apex 123 than a second pair of light rays 740 which also emanate at an azimuthal separation angle ⁇ but reflect from parabolic reflector 122 at a point farther from apex 123 and therefore are separated by a larger distance ⁇ r 4 .
  • the light emanating from gap 130 in a unit of solid angle which reflects from parabolic reflector 122 near apex 123 covers a smaller area than light emanating from gap 130 in a unit of solid angle which reflects from parabolic reflector 122 farther from apex 123. Therefore, as shown in the plot of flux density L(r) versus radius r of FIG. 7c, there is a decrease in the flux with increasing radial distance. However, this effect can be compensated for by using a prism 750 with a corrective curvature as shown in FIG. 7a.
  • conical lens 750 has a corrective curvature, it will be referred to herein as a "conical prism” because, as described below, conical prism lens 750 is designed such that each ray of light which strikes it traveling parallel to axis of symmetry 142 also exits it parallel to axis of symmetry 142.
  • conical prism lens 750 is constructed such that, for a ray 720a traveling parallel to axis of symmetry 142, inner surface 751 where ray 720a' exits is parallel to outer surface 752 where ray 720a entered conical prism lens 750. As shown in FIG.
  • the first pair of rays 710 are separated by a distance ⁇ r 2 prior to incidence on the prism.
  • the curvature of the surfaces of conical prism lens 750 are relatively small and so rays 710" exit conical prism lens 750 separated by a distance ⁇ r 2 ' which is not substantially smaller than ⁇ r 2 .
  • the curvature of conical prism lens 750 acts to concentrate the light farther from axis of symmetry 142 to provide a more uniform output flux density L"(r), as shown in FIG. 7d.
  • conical prism lens 750 For conical prism lens 750 to eliminate the hole in the beam produced by a light shield, it is necessary for light which is reflected by parabolic reflector 122 and passes just outside the radius r of the shield to be refracted so that it exits conical prism lens 750 along the axis of symmetry.
  • prism lens 750 and r is the radius of the light shield, must at least hold for the light rays which exit conical prism lens 750 along the axis of symmetry. Because conical prism lens 750 does not necessarily have a uniform thickness h, the above relation must hold for an effective thickness. As shown in FIG.
  • the effective thickness h' is the projection of the distance ray 720a' travels through conical prism lens 750 on normal vector 762 to the surface of conical prism lens 750 at point 764 where ray 720a enters (which by construction is the same as the projection of the distance ray 720a* travels through conical prism lens 750 on normal 768 to the surface of conical prism lens 750 at point 766 where the ray 720a' exits).
  • this condition is expressed as d f(p) d g(p-d) dp dp where f(p) is the curve describing the outer surface 752 and g(p) is the curve describing the inner surface 751 as a function of radial distance p.
  • the output flux density L"(p) is determined by equating the total flux incident on conical prism lens 750 on a ring of radius p and width ⁇ p with the total flux produced by conical prism lens 750 on a ring of radius (p-d) and width ⁇ p * (1-dd/dp). This provides the output flux density L"(p) given by
  • T ⁇ r ⁇ I , ⁇ ⁇ 2 ⁇ p ⁇ - ⁇ PJ 2 ⁇ (p-d) ⁇ p (1-dd/dp)
  • FIG. 8a shows a cross-sectional view of a lamp 500 where a bi-concave collimating lens 545 is used to collimate light 540 from an elliptical reflector 522 prior to incidence on a conical prism lens 550.
  • a light source 524 such as an arc lamp, located at a focus of the elliptical cross-sections of elliptical reflector 522 produces light which is reflected towards the other focus of the elliptical cross-sections.
  • a shield (not shown) mounted on light source 524 prevents light from exiting lamp 500 without striking reflector 522 and produces a hole in converging light 540 which makes the beam of converging light 540 unsuitable for use as a source of illumination for a projector.
  • Converging light 540 is dif ⁇ fracted by bi-concave collimating lens 545 to produce collimated light rays 540' which still has a central hole.
  • Conical prism lens 550 displaces collimated light rays 540' towards axis of symmetry 542 by an amount equal to the radius of the hole incident on conical prism lens 550, thereby producing a collimated beam 540" without a hole. Therefore, bi-concave collimating lens 545 and conical prism lens 550 form a lens system 560 which acts to collimate the beam of converging light 540 and remove the hole therefrom.
  • FIG. 8b is a cross-sectional view of a lamp 600 where conical prism 650 is used to remove a hole in converging light 640 from elliptical reflector 622, and then a bi-concave collimating lens 645 is used to collimate light 640' exiting conical prism lens 650.
  • a light source 624 such as an arc lamp, located at a focus of the elliptical cross-sections of the elliptical reflector 622 produces light which is reflected by elliptical reflector 622 towards the other focus of the elliptical cross-sections.
  • a shield (not shown) mounted on the light source 624 prevents light from escaping from lamp 600 without striking elliptical reflector 622, and produces a hole in converging light 640 which makes the beam of converging light 640 unsuitable for use as a source of illumination for a projector.
  • Converging light 640 is displaced towards axis of symmetry 642 by conical prism lens 650, thereby removing the hole in the beam of converging light 640. Because the angle between the incident rays of converging light 640 and the normal to the surface of conical prism lens 650 of FIG. 8b is smaller than the angle between the incident rays of converging light 540 and the normal to the surface of conical prism lens 550 of FIG.
  • Bi-concave collimating lens 645 then acts on the converging beam 640' to produce collimated beam 640" where the rays of beam 640" travel parallel to each other.
  • Bi ⁇ concave collimating lens 645 and conical prism lens 650 therefore form a lens system 660 which acts to collimate the beam of converging light 640 and remove the hole therefrom.
  • the hole elimination system can be a mirror system, instead of a lens system.
  • FIG. 9a shows a schematic cross-section of such a lens system.
  • Lamp 820 comprises an arc lamp 824 as the source of light, a parabolic reflector 822 for collimating light, and a light shield 826 for re-directing forwardly emitted light back towards parabolic reflector 822.
  • arc lamp 824 as the source of light
  • parabolic reflector 822 for collimating light
  • a light shield 826 for re-directing forwardly emitted light back towards parabolic reflector 822.
  • This hole can be eliminated by a mirror system comprising a frusto-conical mirror 850 and a conical mirror 860, each disposed symmetrically around cylindrical axis of symmetry 842.
  • Frusto-conical mirror 850 reflects outer light rays 840a and 840f inwards, in a direction generally perpendicular to axis of symmetry 842.
  • conical mirror 860 Upon impinging on conical mirror 860, reflected rays 840a' and 840f are reflected thereby in a direction parallel to axis of symmetry 842 as light rays 840a" and 840f '.
  • rays 840a" and 840f ' form a collimated beam of light without a central hole therein.
  • FIG. 9b shows a possible construction of the mirror system of the previous figure.
  • a frusto-conical piece 870 made of a transparent material such as glass or plastic (e.gippo polycarbonate or acrylic) has a central conical recess 872 formed therein.
  • Frusto-conical reflector 850 can be formed on exterior surface 874 by deposition thereon of a suitably reflective material.
  • conical reflector 860 can be formed on conical interior surface 876.
  • FIG. 9b illustrates only one possible construction, and that many other equivalent constructions are possible, for example by using metal or dielectric reflectors or by using total internal reflection at glass/air interfaces.
  • Lamp 920 comprises arc lamp 924, parabolic reflector 922, and light shield 926, which interact in a manner previously described to produce a collimated beam of light (represented by light rays 940a through 940f) having a central hole.
  • each of light rays 940a through 940f are inwardly reflected, in a direction perpendicular to cylindrical axis of symmetry 942, by frusto-conical mirrors 950a through 950c.
  • each ray is again reflected by the next inner frusto-conical mirror, this time in a direction parallel to axis of symmetry 942.
  • ray 940a after reflection by frusto-conical mirror 950a, is next reflected by frusto-conical mirror 950b.
  • the second reflection is effected by conical mirror 960, but also in a direction parallel to axis of symmetry 942.
  • the net effect is that each ray of light has been displaced inwardly, by a distance equal to about equal to the radius of the central hole, thereby filling it.
  • the interior frusto-conical mirrors (950b and 950c) must be reflective on both their exterior and interior surfaces, but that the outermost frusto-conical mirror (950a) need be reflective only on its interior surface, although as a matter of manufacturing convenience it may also be made reflective at its exterior surface. It will also be appreciated that in this particular instance a series of three frusto-conical mirrors 950a through 950c has been depicted, but that a different number of such mirrors may be used. So far the hole elimination system (whether lens or mirror) has been described as cylindrically symmetric. So the inward displacement of light is independent of rotation around the polar axis.
  • the degree of radial displacement of the light can be made a function of the polar angle of rotation around the optic axis.
  • light efficiency can be improved by having the degree of inward deflection and compression increased for the radial direction that is normal to the longest side of the rectangular image. This becomes much more important for wide screen formats like HDTV at 16:9, and will increase the light efficiency more.
  • a number of differing approaches can be used to accomplish this non- cylindrically symmetric result. One is to draw the desired element profiles for the top and side views; and then to interpolate the intermediate x-sections using eg. an elliptical variation.
  • the hole elimination system (and the beam its generates) be cylindrically symmetric about the central axis of symmetry (e.g., elements 142, 542, 642, 842, and 942); they need only be at least bilaterally symmetric about the axis, for example with the hole- eliminated beam having a rectangular or elliptical cross section.
  • the conical prism of FIG. 3 may have other shapes near the apex since no light is incident on this region; although an arc lamp is preferred because of its small size, other types of light sources, such as fluorescent and incandescent bulbs, may be used; any shape of reflector may be used as long as the lens system, which includes the conical prism lens, acts to collimate the beam, etc.
  • the foregoing detailed description of the invention includes passages which are chiefly or exclusively concerned with particular parts or aspects of the invention.

Abstract

Pour être utile dans les systèmes de projection d'images, les faisceaux de lumière blanche doivent être correctement collimatés et présenter une intensité lumineuse uniforme. Si l'on emploie un réflecteur, par exemple du type parabolique, pour produire de tels faisceaux, il est nécessaire de placer dans le faisceau une lentille prismatique conique (ou d'autres systèmes optiques) pour éliminer le trou produit dans le faisceau par un blindage monté sur la source lumineuse. Pour éliminer ledit trou, il doit exister entre le rayon r du blindage, l'épaisseur h de la lentille prismatique conique, l'indice de réfraction n de la lentille prismatique conique, et l'angle ζ formé par la surface extérieure de ladite lentille et la direction radiale, une relation donnée par la formule: r ≈ h*sinζ*[1 - cosζ*(n?2 - sin2ζ)-1/2¿]. Pour corriger la diminution de l'intensité lumineuse en fonction de la distance radiale, l'angle ζ peut croître avec le rayon. Un lentille de Fresnel équivalant à la lentille prismatique conique peut être utilisée, de sorte que, lorsque le plan d'éclairage est suffisamment éloigné de la lentille de Fresnel, on ne voit pas de bandes noires. Si on utilise un réflecteur non parabolique, le système de lentilles devra comporter un moyen permettant de collimater le faisceau.
PCT/US1995/014109 1994-11-01 1995-10-30 Elimination du trou dans la lumiere emise par une lampe a reflecteur WO1996013943A1 (fr)

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US08/333,098 1994-11-01

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5951135A (en) * 1997-10-14 1999-09-14 Raychem Corporation Color image projection system
US6082863A (en) * 1996-08-16 2000-07-04 Raychem Corporation Color projection prism
CN100363782C (zh) * 2005-01-27 2008-01-23 精工爱普生株式会社 投影机
WO2016193074A1 (fr) * 2015-05-29 2016-12-08 Osram Opto Semiconductors Gmbh Composant opto-électronique doté d'une source de rayonnement

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4637691A (en) * 1983-02-07 1987-01-20 Nippon Kogaku K. K. Mirror converging-type illumination optical system
WO1992016871A1 (fr) * 1991-03-15 1992-10-01 Seiko Epson Corporation Dispositif de visualisation du type par projection

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4637691A (en) * 1983-02-07 1987-01-20 Nippon Kogaku K. K. Mirror converging-type illumination optical system
WO1992016871A1 (fr) * 1991-03-15 1992-10-01 Seiko Epson Corporation Dispositif de visualisation du type par projection

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 7, no. 125 (P - 200) 31 May 1983 (1983-05-31) *

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6082863A (en) * 1996-08-16 2000-07-04 Raychem Corporation Color projection prism
US5951135A (en) * 1997-10-14 1999-09-14 Raychem Corporation Color image projection system
CN100363782C (zh) * 2005-01-27 2008-01-23 精工爱普生株式会社 投影机
WO2016193074A1 (fr) * 2015-05-29 2016-12-08 Osram Opto Semiconductors Gmbh Composant opto-électronique doté d'une source de rayonnement
CN107646145A (zh) * 2015-05-29 2018-01-30 奥斯兰姆奥普托半导体有限责任公司 具有辐射源的光电子组件
JP2018517292A (ja) * 2015-05-29 2018-06-28 オスラム オプト セミコンダクターズ ゲゼルシャフト ミット ベシュレンクテル ハフツングＯｓｒａｍ Ｏｐｔｏ Ｓｅｍｉｃｏｎｄｕｃｔｏｒｓ ＧｍｂＨ オプトエレクトロニクス部品
US10175465B2 (en) 2015-05-29 2019-01-08 Osram Opto Semiconductors Gmbh Optoelectronic component having a radiation source
CN107646145B (zh) * 2015-05-29 2020-06-30 奥斯兰姆奥普托半导体有限责任公司 具有辐射源的光电子组件
DE112016002421B4 (de) 2015-05-29 2022-03-31 OSRAM Opto Semiconductors Gesellschaft mit beschränkter Haftung Optoelektronisches bauelement mit einer strahlungsquelle

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