Umted States Patent [191
`Melby
`
`[11] Patent Number:
`[45] Date of Patent:
`
`5,054,885
`Oct. 8, 1991
`
`[54] LIGHT FIXTURE INCLUDING A
`
`4,011,001 3/1977 Nloriya ....................... ..... .. 350/345
`
`PARTIALLY COLLIMATED BEAM 0F
`
`4,127,771 1/1978 Sick . . . , . . . .
`
`. . . . .. 350/616
`
`LIGHT AND REFLECTIVE PRISMS HAVING
`
`1%;
`
`gc‘lmd Ti
`
`-----
`
`PEAKS LYING ON A CURVED SURFACE
`
`,
`,
`ar ow e a .
`4,629,288 12/1986 Wagers . . . . . .
`
`.
`
`.... ..
`. . . . .. 350/171
`
`[75] Inventor:
`
`Jeffrey J. Melby, Saint Paul, Minn.
`
`4.799.137 l/1989 Aho - - - - - - - -
`
`- - ~ - -- 350/286
`
`,
`
`_
`
`.
`
`_
`
`_
`
`[73] Ass1gnee= Minnesota Mums and
`Manfuacturing Company, Saint Paul,
`Minn.
`
`4,874,228 10/1989 Aho et al. . , . . . .
`
`. . . . . . .. 362/26
`
`4,914,553 4/1990 Hamada et a1. ................... .. 350/345
`
`FOREIGN PATENT DOCUMENTS
`
`[21] App]_ NO‘: 651 110
`’
`Feb. 4, 1991
`
`[22] Filed:
`
`~
`[63]
`
`R
`
`-
`-
`elated U S pphcam" Dam
`Continuation of Ser. No. 255,784, Oct. 11, 1988, aban
`doned.
`
`.
`
`. A
`
`[51] Int. c1.5 ....................... .. F21V 7/00; G02B 27/14
`[52] US. Cl.
`............. .. 359/618; 362/348;
`362/ 307; 362/26; 359/850; 359/638
`[58] Field of Search ............. .. 350/1-71, 169, 616, 612,
`350/286, 345; 362/26, 27, 348, 307, 247
`References Cited
`U.S. PATENT DOCUMENTS
`
`[56]
`
`123823 7/1985 Japan ................................. .. 350/345
`23022 1/1987 Japan ................................. .. 350/345
`
`_
`Primary Examiner—Jon W. Henry
`Attorney, Agent, or Firm-Gary L. Griswold; Walter N.
`Kirn; Stephen w. Buckingham
`.
`
`[57]
`
`ABSTRACT
`
`A light ?xture has a source of partially collimated light
`for emitting light having an axis of collimation. A struc
`tured surface has a plurality of prisms that are rendered
`re?ective for re?ecting light from the light source out
`of the cavity. The peaks of the prisms de?ne a surface at
`least a portion of which makes an acute angle with the
`axis of collimation.
`
`3,877,802 4/1975 Greenspan ........................ .. 350/616
`
`5 Claims, 2 Drawing Sheets
`
`40
`
`Page 1 of 5
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`TOYOTA EXHIBIT 1006
`
`

`

`US. Patent
`US. Patent
`
`Oct. 8, 1991
`Oct. 8, 1991
`
`Sheet 1 of 2
`Sheet 1 of 2
`
`5,054,885
`5,054,885
`
`
`
`Page 2 0f 5
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`Page 2 of 5
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`

`

`US. Patent
`US. Patent
`
`Oct. 8, 1991
`
`Sheet 2 of 2
`
`5,054,885
`5,054,885
`
`
`
`/WWW/Mn.M
`
`
`
`Page 3 of 5
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`

`

`1
`
`5,054,885
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`2
`FIG. 3 is a view of a third embodiment of a light
`?xture according to the invention; and
`FIG. 4 is a view of a light ?xture according to the
`invention having two light sources.
`
`LIGHT FIXTURE INCLUDING A PARTIALLY
`COLLIMATED BEAM OF LIGHT AND
`REFLECTIVE PRISMS HAVING PEAKS LYING
`ON A CURVED SURFACE
`
`This is a continuation of application Ser. No.
`07/255,784 ?led Oct. 11, 1988 now abandoned.
`
`FIELD OF THE INVENTION
`The present invention relates to thin light ?xtures.
`
`15
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`20
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`25
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`DETAILED DESCRIPTION
`FIG. 1 illustrates a ?rst embodiment of the invention.
`In the embodiment of FIG. 1 a housing including walls
`10 and 12 de?nes an optical cavity. The optical cavity
`has an optical window with a light transmitting member
`14, therein. Light transmitting member 14 may be of a
`transparent or translucent material. If desired, light
`transmitting member 14 could include structures such as
`pillow optics or Fresnel prisms.
`A source of partially collimated light 16 is positioned
`inside the optical cavity and adjacent side 10 of the
`housing. Light source 16 may be any source of partially
`collimated light such as a ?uorescent tube or other gas‘
`discharge lighting element with an appropriate re?ector
`or an incandescent light with a re?ector. Alternatively
`light source 16 could include a plurality of light emit
`ting diodes (LEDs).
`Side 22 of wall 12 is a structured surface having a
`plurality of, preferably triangular, prisms, 24, thereon.
`In a preferred embodiment, prisms 24 are linear prisms.
`Prisms 24 are rendered specularly re?ective, typically
`by aluminum vapor coating. It is only necessary that
`prisms 24 be specularly re?ective on the side adjacent
`light source 16, but it is typically easier to vapor coat
`both sides. Such prisms re?ect light from light source 16
`in a predetermined direction. Typically the predeter
`mined direction will be perpendicular to transparent or
`translucent material 14.‘
`Light source 16 emits a beam of substantially colli-'
`mated light having an axis of collimation 18. Line 20 is
`drawn parallel to collimation axis 18. As may be seen,
`the peaks of prisms 24 de?ne a planar surface that makes
`an acute angle 0 with line 20, and thus with collimation
`axis 18. As a result side 22 of wall 12 cuts through the
`beam of light emitted by light source 16. Because struc
`tured surface 22 so cuts through the beam of light emit
`ted by light source 16, the entire aperture of the optical
`window is illuminated.
`The structure of the present invention may be advan
`tageously formed directly on the rear wall of the light
`?xture. Such a structure could be formed by injection
`molding. Alternatively a separate ?lm having the struc
`tured surface described above could be placed in the
`light ?xture.
`FIG. 2 shows an alternative embodiment to‘that of
`FIG. 1. In the embodiment of FIG. 2 structured surface
`22’ is curved. Thus the surface de?ned by the peaks of
`prisms 24 is curved rather than planar. As a result, that
`surface is parallel or nearly parallel to the axis of colli
`mation in the region closest to light source 16, but forms
`a variety of acute angles with it in regions more distant
`from light source 16.' This has the effect of causing
`prisms more distant from light source 16 to intercept a
`greater portion of the beam than those closer to light
`source 16. Because the light beam will naturally expand
`as it progresses to locations distant from the source, the
`curvature helps to maintain uniformity of illumination.
`FIG. 3 illustrates an alternative embodiment wherein
`a housing 30 including walls 32, 34, 36 and 38 de?nes an
`optical cavity having an optical window. A transparent
`or translucent cover 40 lies in the optical window.
`Light from two partially collimated light sources is
`directed from light sources 42 and 44 to structured
`
`BACKGROUND OF THE INVENTION
`In various situations thin light ?xtures are desirable.
`For example, back-lit ?at panel displays normally
`should be kept as thin as possible. When they are thin
`ner they tend to be lighter in weight and more compact,
`both desirable properties when they are used in applica
`tions such as portable computers. Automobile taillights
`and brake lights also should be kept compact where
`possible. This is because space used by such lights
`comes at the expense of luggage space in the vehicle’s
`trunk.
`Various designs for thin panel lighting have been
`proposed. For example, copending, commonly assigned
`US patent application Ser. No. 016,858, ?led Feb. 20,
`1987, now US. Pat. No. 4,789,921 describes a Fresnel
`type re?ector lying on a conic surface. Typically the
`Fresnel-type structures of that re?ector are designed to
`mimic the performance of a parabolic re?ector. The
`30
`conic Fresnel provides a highly efficient compact light
`source, but suffers from the same disadvantage as other
`parabolic re?ectors. That disadvantage is a lack of uni
`formity in intensity of light output. As may be expected,
`regions closer to the light source will be more brightly
`illuminated than those more distant from the light
`source.
`Other designs have been proposed for use when uni
`form illumination is desirable. One such proposal is
`described in commonly assigned, copending US. patent
`40
`application Ser. No; 030,033, ?led Mar. 24, 1987 now
`U.S. Pat. No. 4,799,137. That design utilizes a ?lm
`known as right angle ?lm. The use of right angle ?lm in
`a light ?xture allows the output optical window to be
`very evenly illuminated, but requires the separate con
`struction of the right angle ?lm and the insertion of that
`?lm into the light ?xture. In some situations it would be
`desirable to construct a light ?xture having a perfor
`mance similar to that of the ?xture using right angle
`?lm, without the requirement of the insertion of a sepa
`rate ?lm into the ?xture.
`
`35
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`45
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`50
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`SUMMARY OF THE INVENTION
`According to the invention a housing de?nes an opti
`cal cavity having an optical window. A source of par
`tially collimated light having an axis of collimation is
`located inside the optical cavity. A structured surface
`having a plurality of prisms thereon is positioned within
`the optical cavity such that the prisms re?ect light
`through the optical window. The peaks of the prisms
`de?ne a surface at least a portion of which makes an
`acute angle with the axis of collimation.
`
`55
`
`60
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`FIG. 1 is a view of a ?rst embodiment of a light
`?xture according to the invention;
`FIG. 2 is a view of a second embodiment of a light
`?xture according to the invention;
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`Page 4 of 5
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`3
`surface 46. The peaks of the prisms of structured surface
`46 may de?ne a planar surface lying at an angle to the
`axis of collimation of the light sources, similar to the
`embodiment of FIG. 1 or may de?ne a curved surface
`cutting through the beams of light as in the embodiment
`of FIG. 2.
`FIG. 4 illustrates another embodiment of the inven
`tion wherein light source 14’ includes a light emitter 50
`and a structured surface 52. Structured surface 52 acts
`in a manner similar to structured surface 22 to take light
`from a compact source 50 and provide a linear beam.
`The embodiment of FIG. 4 then acts similarly to the
`embodiment of FIG. 1 with surface 52 acting as a light
`source for structured surface 54.
`I claim:
`1. A light ?xture comprising:
`a housing de?ning an optical cavity having an optical
`window, said housing having an inner surface on a
`side opposite said optical window;
`light emitting means in said housing for emitting a
`partially collimated beam of light having an axis of
`collimation;
`
`5,054,885
`4.
`a plurality of prisms on said inner surface, each of said
`prisms having a specularly re?ective surface on a
`side adjacent said light emitting means for re?ect
`ing light from said light emitting means out of said
`?xture through said optical window, the peaks of
`said prisms de?ning a surface, at least a portion of
`said surface being smoothly curving and forming
`an acute angle with said axis of collimation such
`that said optical window will receive a substan
`tially uniform level of illumination.
`2. The light ?xture of claim 1 further comprising a
`light transmitting member in said optical window.
`3. The light ?xture of claim 2 wherein said prisms
`re?ect light from said light emitting means in a direction
`substantially perpendicular to said light transmitting
`member;
`4. The light ?xture of claim 3 wherein each of said
`specularly re?ective surfaces makes an angle substan
`tially equal to forty-?ve degrees with said axis of colli
`mation.
`5. The light ?xture of claim 1 wherein said prisms are
`linear prisms.
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`Page 5 of 5
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