United States Patent 1191
`Murata et al.
`
`[54] LIGHT EMITTING DIODE LAMP
`
`[75] lnvent°rs= Him“ Murat?“ Terms“ “19mm;
`£31m“! Tabll'a, all of “311115111,
`
`[73] Assignee: Mitsubishi Cable Industries, Ltd.,
`Amagasaki, Japan
`
`[21] Appl. No.: 267,852
`
`[22] Filed:
`
`Nov. 7, 1988
`
`Foreign Application Priority Data
`[30]
`Nov. 17, 1987 [JP]
`Japan .............................. .. 62-290139
`Dec. 29, 1987 [JP]
`Japan .............................. .. 62-336314
`
`H01J 5/16; G09F 13/18
`[51] Int. Cl.5 ............ ..
`[52] US. Cl. .................................. .. 313/500; 313/ 113;
`313/116; 362/297; 362/310; 362/362
`[58] Field of Search ............. .. 313/113, 498, 499, 500,
`313/512, 116; 362/296, 297, 310, 341, 362, 367
`
`4,929,866
`[11] Patent Number:
`[45] Date of Patent: May 29, 1990
`
`[56]
`
`References‘ Cited
`U.S. PATENT DOCUMENTS
`4,009,394 2/1977 Mierzwinski ................. .. 313/512 x
`4,642,513 2/1987 Nyul et a1. .................... .. 313/492 X
`
`FOREIGN PATENT DOCUMENTS
`62409003 5/1987 Japan .
`62-125285 8/1987 Japan .
`62-176887 11/1987 Japan .
`Primary Examiner-Kenneth Wieder
`Attorney, Agent, or Firm-Armstrong, Nikaido,
`Marmelstein, Kubovcik & Murray
`[57]
`ABSTRACT
`It is disclosed a light emitting diode lamp composing a
`window through which light is released forwardly, a
`plurality of light emitting diodes located at a corner of
`the window or behind the frame of the window, and a
`light re?ector having a plurality of light re?ecting faces
`whereby light emitted from the light emitting diodes is
`re?ected toward the window. The lamp is suited as an
`automobile lamp, especially as a tail lamp.
`
`7 Claims, 4 Drawing Sheets
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`K.J. Pretech Ex. 1011
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`Pretech_000512
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`US. Patent May 29,1990
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`Sheet 1 of4
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`4,929,866
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`FIGZ
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`Pretech_000513
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`US. Patent May 29, 1990
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`Sheet 2 of 4
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`FIG.3
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`Pretech_000514
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`US. Patent May 29, 1990
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`Sheet 3 of 4
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`4,929,866
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`FIGS
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`Pretech_000515
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`Pretech_000515
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`US. Patent May 29,1990 ,
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`Pretech_000516
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`1
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`LIGHT EMITTING DIODE LAMP
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`4,929,866
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`2
`BRIEF DESCRIPTION OF THE DRAWINGS
`FIG. 1 is a cross-sectional view of an embodiment of
`the present invention.
`FIG. 2 is a front view of FIG. 1.
`FIG. 3 is a cross-sectional view of another embodi
`ment of the present invention.
`FIG. 4 is a front view of further another embodiment
`of the present invention.
`FIG. 5 is a cross-sectional view of further another
`embodiment of the present invention.
`FIG. 6 is a front view of FIG. 5.
`FIG. 7 is a cross-sectional view of further another
`embodiment of the present invention.
`FIG. 8 is a front view of further another embodiment
`of the present invention.
`
`DETAILED DESCRIPTION OF THE
`INVENTION
`Although a plurality of light emitting diodes are used
`as light source in the present invention, all of these are
`located at a comer or corners of the light releasing
`window thereof or behind the frame of the window.
`Therefore, besides a possible part of the light emitted
`from the diodes going directly toward the window, a
`large portion of the light emitted from the diodes are
`caught in finely divided or distributed condition by a
`plurality of light re?ecting faces of the light re?ector to
`be re?ected thereby toward the window. As a result,
`the light released forward through the window consists
`of a possible portion which is directly caught by the
`window and a majority of re?ected portion in a ?nely
`divided condition, thus achieving to release light as
`even or uniform as possible from all the area of the
`window under the situation of using a minimum number
`of light emitting diodes whose total lighting power falls
`in a range suited, for example, for a tail lamp of automo
`biles.
`Furthermore, the lamp of the present invention may
`be reduced its total thickness so thin as from about 20 to
`about 60 mm by using a thinner light re?ector. Such a
`thinner lamp in total thickness is so expedient, in com
`parison with a conventional ?lament lamp, that it is
`suitable as an automobile lamp, especially as a tail lamp
`for not requiring large space and for easy mounting in
`an automobile.
`Now the present invention will be explained in detail
`by relying on Figures. In FIGS. from 1 to 8, the same
`parts are exhibited by the same numeral or symbol.
`In an embodiment of FIGS. 1 and 2 numeral 1 exhib
`its a lamp case made of a metal or a plastic, numeral 2
`exhibits a light releasing window formed at a front wall
`of the lamp case 1, numeral 3 exhibits a window pane ?t
`at the window 2, numeral 4 exhibits a frame whereby
`the window 2 is formed, and includes an upper frame
`portion 41 and a lower frame portion 42, numeral 5
`exhibits light emitting diodes located behind the upper
`frame portion 41 of the frame 4, numeral 6 exhibits a
`light reflector having a plurality of re?ecting faces 61.
`As the light emitting diode 5 to be used in the present
`invention, suitable is a conventional resin molded one
`wherein a chip of light emitting diode, such as a homo
`junction type, a single hetero-junction type, a double
`hetero junction type, etc., is mounted on the bottom
`surface of a small light re?ecting cap provided with a
`lead frame, and is molded with a transparent organic
`polymer,~such as epoxy resin. There is no limitation
`concerning color of light emitted. For example, red
`
`10
`
`BACKGROUND OF THE INVENTION
`1. Field of the Invention
`The present invention relates to a lamp having light
`emitting diodes as light source, and suited for use as an
`automobile lamp, a room lamp of hotel or house, a night
`signal, especially a tail lamp of an automobile.
`2. Prior Art of the Invention
`There has been used a tail lamp of automobile which
`has a ?lament as a light source. However, the tail lamp
`of ?lament type has many shortcomings, such as con
`suming too much electric power, generating a great
`amount of heat, employing a readily snapping ?lament,
`and the lamp per se being large and heavy or the like.
`In order to overcome these problems, it has been
`proposed that instead of the ?lament lamp, a light emit
`ting diode lamp is adopted, which has such a structure
`that a plurality of light emitting diodes are mounted on
`an insulating board. The proposal may overcome the
`above problems on the conventional ?lament lamp,
`because light emitting diodes emit light by a lower
`25
`voltage and current than those of ?lament lamp, and
`also is small and light, and seldom include problem of
`snapping, thus realizing low electric power consump
`tion, low heat generation, substantially no snapping to
`be able to use semipermanently, small size, and light
`weight.
`‘
`.
`However in this proposal there has been the follow
`ing new problem; that is, tail lamps of automobiles have
`in general a wider window through which light from its
`light source is released forward, and it is required that
`the light released from the window is neither too strong
`nor too weak, or should be moderate, and also is re
`leased as even as possible all over the window. When
`the window is ?lled up with light emitting diodes in
`order to achieve even lighting, the lighting power be
`40
`comes too strong to fail as a tail lamp of automobile. On
`the other hand, when using a small number of light
`emitting diodes in order to make power moderate, the
`lighting becomes spot-like, and therefore it does not
`obtain a lamp which illuminates evenly.
`
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`
`OBJECT OF THE INVENTION
`An object of the present invention is to provide a
`novel lamp having light emitting diodes as light source.
`Another object of the present invention is to provide
`a light emitting diode lamp which is able to lighten as
`even or uniform as possible all over its window with a
`moderate lighting power.
`Further another object of the present invention is to
`provide a light emitting diode lamp being used as a tail
`lamp of automobiles.
`
`SUMMARY OF THE INVENTION
`Stated more speci?cally, the present invention pro~
`vides a light emitting diode lamp comprising a window
`through which light is released forward (hereinafter the
`window is referred to as light-releasing window, or
`simply window), a plurality of light emitting diodes
`located at' a comer of the window or behind the frame
`of the window, and a light re?ector having a plurality
`of light re?ecting faces whereby light emitted from the
`light emitting diodes is re?ected toward the window.
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`light is suited for a stop lamp, tail lamp, etc. of automo
`silica glass and like glasses. More preferable as the win
`bile, yellow light is for a map lamp of automobile and
`dow pane 3 is a light-scatterable plate in order to make
`turn signal lamp, green light is for green signal lamp,
`more even the re?ected light from'the above mentioned
`etc.
`re?ecting faces 61. As a light-scatterable plate a variety
`A small number of light emitting diodes having high
`of plates are employable, if they are able to scatter the
`lighting power or conversely, a large number of light
`re?ected light from the re?ecting faces 61 and release it
`emitting diodes having rather low lighting power may
`out of the window 2. For example, what can be used is
`be used in the present invention. As a chip of light emit
`a plate made of a transparent organic or inorganic mate
`ting diode having high lighting power, it is preferable
`rial including powder of at least one other transparent
`these described in the speci?cation of Japanese patent
`organic or inorganic material in well dispersed state, a
`application Sho 61-92895, which are double hetero
`transparent plate including suitable amount of ?ne voids
`structure having from 1015 to 1020 number of
`or, a transparent plate having a plurality of convex
`atoms/cm3 in concentration of impurity in the active
`lenses, concave lenses, or projections of complex forms
`layer thereof. The light emitting diode can emit stron
`at one side or both sides thereof.
`ger light than conventional diodes under applying an
`The light reflector 6 may be made of a plastic or a
`ordinary voltage to allow to apply more lower voltage,
`metal, and the reflecting faces 61, if necessary in order
`as a result generating fewer heat than the case of con
`to improve their light re?ecting ef?ciency, are ?nished
`ventional diodes during operation. They are stable in
`by applying thereon a grossy plate or vapor deposition
`quality, and may be easily mass-produced in low cost.
`of a metal. More simply and easily, the re?ecting faces
`Each of the re?ecting faces 61 is so inclined that the
`61 may also be ?nished by only sraying a paint mixed
`light emitted from the light emitting diodes 5 is re
`with ?ne powder of a metal. As a metal of those above
`?ected thereby toward the window 5. Because the di
`mentioned, it is exemplified nickel, cromium, aluminum,
`odes 5 are located behind the upper frame portion 41,
`gold, silver, etc.
`the light emitted therefrom does not go toward the
`In the case where the light emitting diodes 5 are so set
`window 2 directly, but are caught and reflected by
`that the direction of their center axes A of light emission
`means of the re?ecting faces 61 to go toward the win
`become parallel to the window 2 as seen in FIG. 1, the
`dow 2 as seen in FIG. 1. Therefore the light emitted
`inclination angle (the angle against the above center
`from one diode 5 is re?ected by all of the re?ecting
`axises A of light emission of the diode 5) of each re?ect
`faces 61 in ?nely divided condition. As a result, each
`ing face 61 may be, for example, around 45 degrees.
`re?ecting face 61 behaves as if a light source, realizing
`Desired results may also be obtained by the following
`the window releasing light substantially evenly from all
`other embodiments concerning the inclination angle of
`the area thereof.
`reflecting face 61. In a certain case, the inclination angle
`Differing from the case of embodiment shown in
`of the re?ecting face 61 closest to the light emitting
`FIGS. 1 and 2, in the present invention a part of the
`diodes 5 is around 20 degrees, and becoming gradually
`light from the light emitting diodes 5 may be caught
`greater further away from the diodes 5, the angle of the
`directly by the window 2 and released therethrough
`re?ecting face farthest to the diodes 5 is around 60
`forward, if the diodes 5 are located not at the center or
`degrees. In another case in contrast with the above, the
`its vicinity of the window 2, but at a corner or corners
`angle of the re?ecting face closest to the diodes 5 is
`of the window 2. In such location of the diodes 5 the
`around 60 degrees, and becoming gradually smaller
`light released from the window 2 become also substan
`further away from the diodes 5, the angle of the re?ect
`tially even so as to satisfy various standards, for exam
`ing surface farthest to the light emitting diodes 5 is
`ple, S A E(Society of Automotive Engineers) standard,
`around 20 degrees. In yet another case, the angles of
`because of the following reason: that is, by locating the
`re?ecting faces 61 do not change gradually, but change
`diodes at a corner or corners of the window 2 there is,
`at random or are made uniform.
`besides the direct light, a great amount of light which is
`Though the maximum thickness of the light re?ector
`caught and re?ected by the re?ecting faces 61, and the
`6, which is usually equal to the distance between inner
`direct light is diluted by the re?ected light from the
`surfaces of the case 1 is varied according to usage of the
`re?ecting faces 61.
`present lamp, it is, for example, from about 10 to about
`Setting aside the above mentioned modi?ed embodi
`60 mm, preferably from about 15 to about 50 mm, when
`ment, in order to obtain even illumination it is prefera
`used as a tail lamp of an automobile.
`ble that the light emitting diodes are so located that at
`A certain concrete design of the embodiment of FIG.
`least §, especially at least 5 of the light therefrom can
`1 is shown below.
`not observe directly from outside of the window 2. This
`A case 400 mm in length, 150 mm in height, and 30
`may realize, for example, by a manner wherein a resin
`mm in thickness has a light releasing window at one
`molded light emitting diodes is so installed that at least
`wall thereof. The window, which is formed by an upper
`a part of the total length of the resin mold portion
`frame portion 10 mm in width and a under frame por
`which includes a chip of diode is behind the frame 4.
`tion 10 mm in width and therefore is 400 mm in length
`Though the light releasing window 2 may be free
`and 130 mm in height, is fitted with a pane made of
`from any pane, it is preferable to have a window pane 3
`transparent polycarbonate and having a plurality of
`as shown in FIG. 1 from various views, such as prevent
`convex lenses on its one surface. Twenty resin-molded
`ing from moisture, dust and like, or for fine view etc.
`light emitting diodes are mounted on the center of the
`The window pane 3 may be a simple transparent plate
`bottom inner-surface of the case with an uniform dis
`composed of a material such as polycarbonate, acryl
`tance to render their center axes of light vertical against
`resin, epoxy resin, polypropylene, nylon, polychlorotri
`the bottom vinner-surface. The individual resin-molded
`?uoroethylene,
`ethylene-tetra?uoroethylene
`light emitting diode comprises a chip of light emitting
`copolymer, polyvinylidene chloride, fluorinated ethy
`diode of 350 um square having a double-hetero struc
`lene-propylene-copolymer, polyethylene telephthalete,
`ture which is mounted on the bottom surface of a light
`and like transparent organic polymer, and soda glass,
`re?ecting cap provided with a lead frame, and is
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`In the embodiment shown in FIG. 8, the light emit
`molded with a transparent epoxy resin, and is 12 mm in
`molding resin length, 2000 millicandela in lighting
`ting diodes 5 are mounted behind the upper frame por
`power, and 5 degrees in half angle. Each resin-molded
`tion 41 and the under frame portion 42 separetely as
`seen in FIG. 4, and a light re?ector 6 is provided with
`light emitting diode is so mounted on the bottom inner
`two groups of re?ecting faces participating with each
`surface of the case that the top portion, about 2.5 mm, of
`group of the light emitting diodes 5 respectively to
`the molding resin length thereof takes a position higher
`re?ect light toward the window 2.
`than the level of the upper edge of the under frame
`The present invention may include a variety of modi
`portion. The case is provided therein with a light re?ec
`?ed embodiments. The position and inclination angle
`tor which is 20 mm in the maximum thickness, and has
`twenty step-wise re?ecting faces. The inclination angle
`etc. of each re?ecting face of a light re?ector may be so
`designed as to be able to re?ect effectively light toward
`(the angle against the center axis A of the light emission
`the light releasing window according to the set position
`of the resin molded light emitting diode) of the re?ect
`and center axes A of light emission of light emitting
`ing face closest to (about 5 mm) the diodes is 40 degrees,
`diodes. Furthermore, each re?ecting face of the light
`and becoming gradually greater further away from the
`re?ector may be ?at, convex, concave, and also may
`diodes, the angle of the re?ecting face farthest to (about
`includes two or more faces.
`130 mm) the diodes is 50 degrees. This embodiment is
`The light emitting diodes may be located separately
`excellent in evenness of lighting and moderate in light
`not only the top and/or bottom of the light releasing
`ing power to satisfy, as a tail lamp of automobile, the S
`window, but also the right and/or left, or all round of
`A E standard.
`the window. A convex lens may be positioned in front
`In the embodiment shown in FIG. 3, the light emit
`of each light emitting diode to collect the light from the -
`ting diodes 5 are mounted behind the upper frame por
`diode and to send out toward the light re?ector.
`tion 41 to be able to emit light toward the inner wall 11
`As described above, the light re?ectors 6 used in the
`of the case 1, and a light re?ector 6 provided with re
`embodiments of FIGS. 5 to 8 have two functions of
`?ecting faces 61 having a saw-like structure in cross
`re?ection by the action of the re?ecting faces 61 and
`section is set on the inner wall 11.
`scattering the re?ected light by the action of convex
`In the embodiment shown in FIG. 4, the light emit
`lenses 64 to make even the light released forward from
`ting diodes 5 are mounted behind the upper frame por
`the light releasing window 2. Instead of the re?ectors 6,
`tion 41 and the under frame portion 42 separetely as
`a variety of modi?ed re?ectors may also be employed.
`seen in FIG. 4, and a light re?ector 6 is provided with
`For example, those having concave lenses, both of
`two groups of re?ecting faces participating with each
`covex lenses and concave lenses, or projections and/or
`group of the light emitting diodes 5 respectively to
`cavities of complex forms, on their head surfaces which
`re?ect light toward the window 2.
`are ?tted into the window 2, or those which, though
`The light re?ector 6 used in each embodiment shown
`having a ?at head surface, per se are constructed with a
`in FIGS. 5 to 8, is made of a transparent material such
`light-scatterable material, such as a mixture composed
`as an organic polymer, glass etc. mentioned before and
`of a transparent organic or inorganic material including
`has re?ecting faces 61 on its tail surface 62, and also the
`powder of at least one other transparent organic or
`head surface 63, which is ?tted into its light releasing
`inorganic material in a well dispersed state, a transpar
`window 2 and has convex lenses 64. The head surface
`ent organic or inorganic material including suitable
`63 functions to scatter the re?ected light from the re
`amount of ?ne voids.
`?ecting faces 61 by the action of convex lenses 64. The
`embodiments of FIGS. 5 to 8 are advantageous for their
`commercial production with low cost due to the em
`ployment of the above-mentioned light re?ector 6
`which serves both as a light scattering means and as a
`pane of the window 6.
`In the embodiment shown in FIGS. 5 and 6 the light
`emitting diodes 5 are located behind the upper frame
`portion 41 of the window 2. A light re?ector 6 has
`step-wise re?ecting faces 61 on the tail surface 62
`thereof, and also has convex lenses 64 regularly formed
`on its head surface 63 which is fitted into the window 2.
`The light re?ector 6 is a right-angled triangle in cross
`section as a whole, and may be prepared by ?rst mold
`ing a preform thereof having a right-angled triangle in
`cross section and a stair on its tail surface, and then by
`applying on the tail surface a grossy plate or vapor
`deposition of a metal, or by spraying a paint mixed with
`?ne powder of a metal.
`In the embodiment shown in FIG. 7, the light emit
`ting diodes 5 are mounted behind the upper frame por
`tion 41 to be able to emit light toward the inner wall 11
`of the case 1, as similar to the embodiment of FIG. 3. A
`light re?ector 6 has light re?ecting faces 61 of saw-like
`structure in cross-section on the tail surface 62 which is
`parallel to the inner wall 11 of the case 1. The light
`re?ector 6 is a rectangular form in cross-section as a
`whole.
`
`EFFECT OF THE INVENTION
`Various problems encountered in conventional ?la
`ment lamps, such as consumtion of much energy, high
`heat generation, snapping of ?lament, big size and
`heavy weight of lamp itself, are solved by the lamp of
`the present invention with the use of light emitting
`diodes as lighting source.
`On the other hand, though there is a problem of light
`, ing becoming spot-like, when using a small number of
`light emitting diodes in order to obtain moderate light
`ing power, the problem are overcome by the present
`invention to realize even illumination from all the light
`releasing window with the use of a speci?c light re?ec
`tor.
`Furthermore, the lamp of the present invention may
`be reduced its total thickness so thin as from about 20 to
`about 60 mm by using a thinner light re?ector. Such a
`thinner lamp is so advantageous, in comparison with a
`conventional ?lament lamp, and is suitable as an auto
`mobile lamp, especially, as a tail lamp, for not receiving
`large space and is easy for mounting in an automobile.
`While the invention has been particularly shown and
`described in reference to preferred embodiments
`thereof, it will be understood by those skilled in the art
`that changes in form and details may be made therein
`without departing from the spirit and scope of the in
`vention.
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`What is claimed is:
`1. A light emitting diode lamp comprising: a case;
`a plurality of light emitting diodes disposed within
`said case;
`a window forming a part of said case and having at
`least one window frame, said window allowing
`light emitted from said plurality of light emitting
`diodes to pass therethrough, said plurality of light
`emitting diodes being secured at a comer of said
`window and behind said window frame;
`light re?ector means having a plurality of light re
`?ecting faces for dividing and re?ecting said light
`from said plurality of light emitting diodes, and
`light-scattering means for scattering said light from
`said light re?ector means to thereby have said light
`substantially uniformly pass through said window.
`2. A light emitting diode lamp as de?ned in claim 1,
`wherein said case has said light re?ector on an inner
`surface opposite said window.
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`’ 3. A light emitting diode lamp as de?ned in claim 1,
`wherein said light re?ector has a plurality of stepped
`light re?ecting faces.
`4. A light emitting diode lamp as de?ned in claim 1,
`wherein said light re?ector has a plurality of light re
`?ecting faces which are saw-like structures in cross-sec
`tion.
`5. A light emitting diode lamp as de?ned in claim 2,
`wherein the light emitting diodes are separately located
`behind said upper and lower frames of said window.
`6. A light emitting diode lamp as de?ned in claim 2,
`wherein said light re?ector comprises a transparent
`material, and has a plurality of re?ecting faces on a ?rst
`end surface and a second end surface positioned in said
`window.
`7. A light emitting diode lamp as de?ned in claim 2,
`wherein said lamp is for use as a tail lamp of an automo
`bile.
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