United States Patent [191'
`Mizobe
`
`[11] Patent Number:
`[45] Date of Patent:
`
`5,057,974
`Oct. 15, 1991
`
`[54] SYSTEM FOR UNIFORMLY
`ILLUMINATING LIQUID CRYSTAL
`DISPLAY BOARD FROM REAR SIDE
`Tatsuji Mizobe, l-21-3, Sugano,
`[76] Inventor:
`lchikawa-Shi, Chiba-Ken, Japan
`[21] Appl.No.: 541,944
`[22] Filed:
`Jun. 22, 1990
`
`[51] 1111.0.5 .............................................. .. F21V 8/00
`[52] 11.5.0. ...................................... ..362/26;362/27;
`362/31; 362/331
`[58] Field ofSearch ................... .. 362/31, 26, 27, 331,
`362/812, 311; 40/546
`References Cited
`U.S. PATENT DOCUMENTS
`
`[56]
`
`3,328,570 6/1967 Balchunas ........................... .. 362/31
`4,096,550 6/1978 Boller et a1. ..... ..
`362/31
`4,642,736 2/1987 Masuzawa et a1.
`362/31
`4,714,983 12/1987 Lang ................................... .. 362/31
`
`4.729.067 3/1988 Ohe . . . . .
`
`. . . . . . . . . .. 362/31
`
`4,860,171 8/1989 Kojima ................................ .. 362/31
`Primary Examiner-Ira S. Lazarus
`Assistant Examiner-Sue Hagarman
`Attorney, Agent, or Firm—-Cushman, Darby & Cushman
`[57]
`ABSTRACT
`A system for uniformly illuminating a liquid crystal
`
`display board from the rear side includes a main body as
`an essential component. The main body includes a trans
`parent substrate made of transparent resin, a ?rst coated
`layer on the front surface of the transparent substrate
`made of transparent resin having a refractive index
`different from that of the transparent substrate, a second
`coated layer on the rear surface of the transparent sub
`strate made of transparent resin having a refractive
`index different from that of the transparent substrate
`and a rugged layer on the second coated layer made of
`transparent resin suitably employable for forming an
`underlying layer. A plurality of light sources each in the
`form of a fluorescent lamp are arranged in the transpar
`ent substrate in a spaced relationship. The rugged layer
`has a number of light re?ecting means in the form of
`concavities and convexities formed on the front surface
`of the rugged layer for the purpose of irregularly re
`?ecting light from each ?uorescent lamp. The light
`re?ecting means are distributed with a density per unit
`area which is determined to increase in inverse propor
`tion to a square of the distance as measured from each
`?uorescent lamp to keep brightness substantially uni
`form over the whole surface of the transparent sub
`strate.
`
`8 Claims, 2 Drawing Sheets
`
`LGD_000698
`
`LG Display Ex. 1014
`
`

`

`U.S. Patent
`
`Oct. 15,1991
`
`Sheet 1 of 2
`
`- 5,057,974
`
`H63
`
`LGD_000699
`
`

`

`US. Patent
`
`Oct. 1s,~ 1991
`
`Sheet 2 of 2
`
`- 5,057,974
`
`LGD_000700
`
`

`

`1
`
`5,057,974
`
`SYSTEM FOR UNIFORMLY ILLUMINATING
`LIQUID CRYSTAL DISPLAY BOARD FROM REAR
`SIDE
`
`BACKGROUND OF THE INVENTION
`1. Field of the Invention
`The present invention relates to a system for uni
`formly illuminating a liquid crystal display board from
`the rear side wherein a parallel light beam is emitted in
`the form of re?ected light from a main body located
`behind the liquid crystal display board with substan
`tially uniform brightness over the whole surface of the
`screen of the liquid crystal display board.
`2. Description of the Prior Art
`In recent years, a number of liquid crystal display
`boards have been increasingly used for word proces
`sors, personal computors and so forth to display charac
`ters, numerals or the like with a high degree of resolu
`tion. To practically activate the liquid crystal display
`board, a plurality of large scale integrated circuits are
`incorporated in a work station for each word processor
`or personal computor.
`With the conventional liquid crystal display board
`practically used in that way, it has been found that the
`liquid crystal display board has the following draw
`backs.
`Although the liquid crystal display board has a high
`degree of resolution, it is not easy to allow brightness to
`be substantially uniformly distributed over the whole
`surface of the liquid crystal display board. In practice,
`brightness decreases more and more in inverse propor
`tion to a square of the distance as measured from a light
`source with the result that characters, numerals or the
`like on the screen of the liquid crystal display board
`are not uniformly visually recognized by an operator
`who is sitting in front of the word processor, personal
`computor or the like.
`To assure that characters, numerals or the like on the
`screen of the liquid crystal display board are more
`clearly recognized by the operator, a proposal has been
`made such that light generated by a lamp is re?ected at
`a reflective mirror which is disposed behind the liquid
`crystal display board and of which surface is treated to
`a frosted plane so that a parallel light beam is emitted
`toward the liquid crystal display board from the re?ec
`tive mirror. With this proposal, however, brightness is
`not satisfactorily uniformly distributed over the whole
`surface of the liquid crystal display board. In addition, it
`is not easy to provide a high degree of brightness for the
`screen of the liquid crystal display board with the afore
`mentioned proposal. Moreover, arrangement of the
`re?ective mirror has been accomplished at expensive
`cost.
`
`SUMMARY OF THE INVENTION
`The present invention has been made with the forego
`ing background in mind.
`An object of the present invention is to provide a
`system for uniformly illuminating a liquid crystal dis
`play board from the rear side wherein brightness is
`uniformly distributed over the whole surface of the
`liquid crystal display board.
`Another object of the present invention is to provide
`a system for uniformly illuminating a liquid crystal
`display board from the rear side wherein the system is
`constructed at inexpensive cost.
`
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`2
`To accomplish the above objects, there is provided
`according to one aspect of the present invention a sys
`tem for uniformly illuminating a liquid crystal display
`board from the rear side, wherein the system includes as
`an essential component a rectangular main body located
`behind the liquid crystal display board in a spaced rela
`tionship, the main body having a con?guration substan
`tially identical to that ofthe liquid crystal display board
`and including a rectangular transparent substrate made
`oftransparent resin, a ?rst coated layer deposited on the
`front surface of the transparent substrate with transpar
`ent resin, the ?rst coated layer having a refractive index
`different from that of the transparent substrate, a second
`coated layer deposited on the rear surface of the trans
`parent substrate resin, the second coated layer having a
`refractive index different from that of the transparent
`substrate, a rugged layer deposited on the second
`coated layer with transparent resin suitably employable
`for forming an underlying layer, the rugged layer in
`cluding a number of light reflecting means in the form
`of concavities and convexities on the front surface of
`the rugged layer for irregularly reflecting light from
`each light source, the light re?ecting means being dis
`tributed with a density per unit area which increases in
`inverse proportion to a square of the distance as mea
`sured from each light source to keep brightness substan
`tially uniform over the whole surface of the transparent
`substrate, and a plurality of light sources for generating
`light to be irradiated in the interior of the transparent
`substrate.
`The light reflecting means are formed in a dot-shaped
`pattern as viewed from the front side.
`Alternatively, the light re?ecting means may be
`formed in a straight line-shaped pattern as viewed from
`the front side.
`Usually, a ?uorescent lamp is employed for the re
`spective light sources, and the ?uorescent lamps are
`arranged in the transparent substrate in a spaced rela
`tionship.
`Alternatively, four ?uorescent lamps may be ar
`ranged along four sides of the transparent substrate.
`Further. according to another aspect of the present
`invention, there is provided a system for uniformly
`illuminating a liquid crystal display board from the rear
`side, wherein the system includes as an essential compo
`nent a circular main body located behind the liquid
`crystal display board in a spaced relationship, the main
`body having a con?guration substantially identical to
`that of the liquid crystal display board and including a
`circular transparent substrate made of transparent resin.
`a ?rst coated layer deposited on the front surface of the
`transparent substrate with transparent resin, the ?rst
`coated layer having a refractive index different from
`that of the transparent substrate, a second coated layer
`deposited on the rear surface of the transparent sub
`strate with transparent resin. the second coated layer
`having a refractive index different from that of the
`transparent substrate, a rugged layer deposited on the
`second coated layer with transparent resin suitably em
`ployable for forming an underlying layer, the rugged
`layer including a number oflight re?ecting means in the
`form of concavities and convexities on the front surface
`of the rugged layer for irregularly re?ecting light from
`a light source, the light re?ecting means being distrib
`uted with a density per unit area which increases in
`inverse proportion to a square of the distance as mea
`sured from the light source to keep brightness substan
`tially uniform over the whole surface of the transparent
`
`LGD_000701
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`

`3
`substrate, and a single light source disposed at the cen
`tral part ofthe transparent substrate for generating light
`to be irradiated in the interior of the transparent sub
`strate.
`The light re?ecting means are formed in a dot-shaped
`pattern as viewed from the front side.
`Alternatively, the light re?ective means may be
`formed in a concentric circular line-shaped pattern as
`viewed from the front side.
`As the light sources are turned on, light is irradiated
`toward the light re?ecting means in the transparent
`substrate. Irregularly re?ected light is repeatedly re
`?ected further in the transparent substrate between the
`coated layers, whereby a parallel light beam is emitted
`from the transparent substrate through the front coated
`layer. Since a density of distribution of the light re?ect
`ing means per unit is determined to increase in inverse
`proportion to a square of the distance as measured from
`each light source, brightness is substantially uniformly
`distributed over the whole surface of the screen of the
`liquid crystal display board with the result that charac
`ters, numerals or the like on the screen of the liquid
`crystal display board are clearly visually recognized by
`an operator.
`Other objects, features and advantages of the present
`invention will become apparent from reading of the
`following description which has been made with refer
`ence to the accompanying drawings.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`The present invention is illustrated in the following
`drawings in which:
`FIG. 1 is a sectional plan view of a main body for a
`system for uniformly illuminating a rectangular liquid
`crystal display board from the rear side in accordance
`with an embodiment of the present invention;
`FIG. 2 is a vertical sectional view of the main body
`taken in along line II-II in FIG. I, particularly illus
`trating a number of light re?ecting means arranged in a
`dot-shaped pattern;
`FIG. 3 is a vertical sectional view of the main body
`taken along line III——III in FIG. 1, particularly illustrat
`ing a number of light re?ecting means arranged in a
`straight line-shaped pattern;
`FIG. 4 is a sectional plan view of a main body for a
`system for uniformly illuminating a circular liquid crys
`tal display board from the rear side in accordance with
`another embodiment of the present invention;
`FIG. 5 is a vertical sectional view of the main body
`taken along line V—V in FIG. 4. particularly illustrat
`ing a number of light re?ecting means arranged in a
`dot-shaped pattern;
`FIG. 6 is a vertical sectional view of the main body
`taken along line VI-VI in FIG. 4, particularly illustrat
`ing a number of light re?ecting means arranged in a
`concentric circular line-shaped pattern; and
`FIG. 7 is a fragmentary enlarged sectional view of
`the main body for the system of the present invention.
`
`45
`
`DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`Now, the present invention will be described in detail
`hereinafter with reference to the accompanying draw
`ings which illustrate preferred embodiments thereof.
`FIGS. land 2 illustrate a system for uniformly illumi
`nating a rectangular liquid crystal display board (not
`shown) from the rear side in accordance with an em
`bodiment of the present invention. FIG. 1 is a sectional
`
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`5,057,974
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`4
`plan view of the system and FIG. 2 is a vertical sec
`tional view of the system taken in line II-II in FIG. I.
`The system includes as an essential component a main
`body A in the form ofa transparent plate and two lamps
`6 arranged in the interior of the main body A each
`serving as a light source. The main body A is con
`structed in the following manner. Specifically, the main
`body A includes a thin transparent substrate I made of.
`e.g., acrylic resin or the like material having an excel
`lent light permeability, and coated layers 2 and 3 are
`deposited on front and rear surfaces of the substrate 1.
`In addition, a rugged layer 4 having a large number of
`concavities and convexities formed on the front surface
`thereof is interposed between the rear surface of the
`transparent substrate 1 and the coated layer 3 by em
`ploying a coating process. Each of the concavities and
`the convexities is dimensioned within the range of 2
`microns to 3 microns so that it can not visually be rec
`ognized by eyes of an operator who is sitting in front of
`the liquid crystal display board. Therefore, such con
`cavities and convexities have no effect on the back
`ground as viewed in the thickness direction of the trans
`parent substrate 1. In practice, the concavities and the
`convexities on the rugged layer 4 serve as light re?ect
`ing means identified by reference numeral 5. A density
`of distribution of the light re?ecting means 5 per unit
`area is determined in inverse proportion to a square of
`the distance as measured from each stationary light
`source 6 to keep brightness substantially uniform over
`the whole surface of the transparent substrate 1.
`In the shown embodiment of the present invention,
`the light re?ecting means 5 are formed on the rugged
`layer 4 in a dot-shaped pattern as viewed from the front
`side by employing a conventional screen printing pro
`cess or the like. After completion of the printing opera
`tion, the transparent substrate 1 having a number of
`light re?ecting means 5 formed on the coated layer 3 is
`placed in a baking oven (not shown) so that the light
`re?ecting means 5 are baked at a lower temperature in
`the oven. Thus. the light re?ecting means 5 are immov
`ably deposited on the coated layer 3 of the transparent
`substrate 1.
`Usually, a ?uorescent lamp is used for each light
`source 6. As is well known. the ?uorescent lamp 6 has
`optical characteristics that brightness in the middle part
`is higher than that at opposite ends of the ?uorescent
`lamp. As is apparent from FIG. 2, a density of the light
`re?ecting means 5 per unit area is distributed in inverse
`proportion to a square of the distance as measured from
`the ?uorescent lamp 6. To assure that brightness is
`substantially uniformly distributed over the whole sur
`face of the transparent substrate 1. a density ofdistribu
`tion ofthe light re?ecting means 5 per unit area is prac
`tically determined to increase in inverse proportion to a
`square of the distance as measured from each light
`source 6, as mentioned above. With such construction.
`when the liquid crystal display board is practically used.
`the ?uorescent lamps 6 are turned on. Light is irradiated
`from the ?uorescent lamps 6 in the interior of the trans
`
`parent substrate 1 toward the light re?ecting means As light is irradiated in that way, irregularly re?ected
`
`light is repeatedly re?ected further in the interior of the
`transparent substrate 1 between the both coated layers 2
`and 3, whereby correctly re?ected light in the form of
`a parallel light beam as identified by an arrow marl; D
`in FIG. 1 is emitted toward the liquid crystal display
`board from the transparent substrate I through the
`coated layer 2, while exhibiting substantially uniform
`
`LGD_000702
`
`

`

`5
`distribution of brightness across the whole front surface
`of the main body A.
`In FIG. 2, reference numeral 7 designates an end
`plate at opposite ends of the transparent substrate 1 for
`the purpose of preventing light from being uselessly
`emitted to the outside therethrough.
`Next, operation of the system as constructed in the
`above-described manner will be described below.
`When the ?uorescent lamps 6 are turned on, light
`generated by the ?uorescent lamps 6 is irradiated in the
`interior of the transparent substrate 1 so that it collides
`with the light reflecting means 5 on the rugged layer 4
`of the coated layer 3 on the rear surface of the transpar
`ent substrate 1 with a density of distribution of the light
`re?ecting means 5 per unit area which is determined to
`increase in inverse proportion to a square of the distance
`as measured from each ?uorescent lamp 6 to assure
`substantially uniform distribution of brightness over the
`whole surface of the transparent substrate 1. The light
`re?ecting means 5 are prepared in the form of concavi
`ties and convexities on the coated layer 3 on the rear
`surface of the transparent substrate 1 by using special
`ink suitably employable for forming an underlying layer
`for the purpose of light re?ection, whereby light is
`irregularly re?ected along normal lines (not shown)
`extending at a right angle relative to the surface of each
`concavity and convexity. As light is repeatedly re
`?ected in that way, a phenomenon of light illumination
`appears with light forwardly coming from the light
`re?ecting means 5 while forming a parallel light beam in
`the D arrow-marked direction. To assure that bright
`ness is substantially uniformly distributed across the
`whole surface of the transparent substrate 1, a density of
`arrangement of the light re?ecting means 5 per unit area
`is determined to increase in inverse proportion to a
`square of the distance as measured from each ?uores
`cent lamp 6, whereby correctly re?ected light D in the
`form of a parallel light beam is forwardly emitted
`toward the liquid crystal display board through the
`transparent substrate 1 and the coated layer 2 with sub
`stantially uniform brightness over the whole surface of
`the transparent substrate 1. Consequently, an operator
`sitting in front of the liquid crystal display board can
`visually clearly recognize characters, numerals and so
`forth on the screen of the liquid crystal display board.
`As the ?uorescent lamps 6 are continuously turned
`on, the transparent substrate 1 becomes hot due to trans
`mission of heat from the ?uorescent lamps 6. However,
`since air ?ows from the bottom toward the top of the
`transparent substrate 1 under a so-called chimney effect,
`as represented by reference numeral 10 in FIG. 1, the
`transparent substrate 2 is effectively cooled by the air
`?ow 10.
`In the embodiment shown in FIG. 1, the light re?ect
`ing means 5 are arranged in a dot-shaped pattern as
`viewed from the front side. However, the present in
`vention should not be limited only to this. Alterna
`tively, the light re?ecting means 5 may be arranged in a
`straight line-shaped pattern, as shown in FIG. 3. As is
`apparent from the drawing, the number of straight lines
`decreases more and more as each line shifts close to
`each ?uorescent lamp 6. To the contrary, the number of
`lines increases more and more as each line shifts away
`from the ?uorescent lamp 6. Also according to the
`embodiment of the present invention shown in FIG. 3,
`the liquid crystal display board is substantially uni
`formly illuminated with light forwardly emitted from
`the light re?ecting means 5 in the transparent substrate
`
`45
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`5,057,974
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`5
`
`6
`1 through the coated layer 2 with the same advanta
`geous effects as those in the embodiment in FIG. 2.
`FIGS. 4-6 illustrated a system for uniformly illustrat
`ing a circular liquid crystal display board from the rear
`side in accordance with a second embodiment of the
`present invention. FIG. 5 is a vertical sectional view
`along V—V in FIG. 4 which schematically illustrates a
`transparent substrate for the system in a case where a
`large number of light re?ecting means 5 are arranged in
`the form of concavities and convexities in a dot-shaped
`pattern as viewed from the front side. FIG. 6 is a verti
`cal sectional view along VI-VI in FIG. 4 which sche
`matically illustrates a transparent substrate for the sys
`tem in a case where a large number of light re?ecting
`means are arranged in the form of annular concavities
`and convexities in a concentric circular line-shaped
`pattern as viewed from the front side. AS is apparent
`from the drawings, in this embodiment, the transparent
`substrate 1 is designed in a circular disc-shaped configu
`ration.
`As shown in FIG. 4 a single light source 6 is located
`at the central part of the transparent substrate 1, and a
`mounting plate 8 made of metallic material for mount
`ing the light source 6 is formed with a number of axially
`extending fins 9 in order to radiate heat generated by
`the light source 6 to the outside for the purpose of cool
`ing the transparent substrate 1.
`Generally, brightness on the transparent substrate 1
`decreases in inverse proportion to a square of the dis
`tance as measured from the light source 6. However,
`since a density of distribution of the light re?ecting
`means 5 per unit area, which are deposited on the
`coated layer 3 by employing a conventional screen
`printing process or the like, is determined to increase in
`inverse proportion to a square of the distance as mea
`sured from the light source 6 in the entirely same man
`ner as in the foregoing embodiment of the present in
`vention, a liquid crystal display board (not shown)
`placed in front of the transparent substrate 1 is substan
`tially uniformly illuminated with light forwardly emit
`ted from the light re?ecting means 5 through the coated
`layer 2.
`The operation of the system in this embodiment is the
`same as that of the system in accordance with the fore
`going embodiment. Thus, repeated description will not
`be required.
`FIG. 7 is a fragmentary enlarged sectional view of
`the transparent substrate for the system in accordance
`with the aforementioned embodiments of the present
`invention, particularly illustrating in detail a laminated
`structure of the main body A which is an essential com
`ponent of the system. As is apparent from the drawing,
`the laminated structure of the main body A comprises a
`transparent substrate 1, a coated layer 2 on the front side
`made of transparent resin having a refractive index
`different from that of the transparent substrate 1, a
`coated layer 3 on the rear side made of transparent resin
`having a refractive index different from that of the
`transparent substrate 1. a rugged layer 4 made of an
`other transparent resin preferably employable for form
`ing an underlying layer and a number of light re?ecting
`means 5 in the form of concavities and convexities
`formed on the rugged layer 4.
`The present invention has been described above with
`respect to a case where the system is used for uniformly
`illuminating a liquid crystal display board which has
`been widely employed as a display means for a word
`processor, a personal computor and so forth. However,
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`LGD_000703
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`

`5,057,974
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`5
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`3O
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`7
`the present invention should not be limited only to a
`liquid crystal display board. Alternatively, an object to
`be uniformly illuminated may be a number plate for a
`motorcar wherein the number plate has a plurality of
`characters and numerals punched from a base plate
`made of metallic material so as to indicate a speci?c car
`number allocated to the motorcar. In this case, with the
`system ofthe present invention, the punched characters
`and numerals are uniformly illuminated from the rear
`side in the nighttime when lamps are turned on so that
`the number plate is visually clearly recognized by a
`person at a remote location in front of the motorcar.
`While the present invention has been described above
`with respect to two preferred embodiments, it should of
`course be understood that the present invention should
`not be limited only to those embodiment but various
`changes or modi?cations may be made without depar
`ture from the scope of the invention as de?ned by the
`appended claims.
`What is claimed is:
`1. A system for uniformly illuminating a rectangular
`liquid crystal display board from the rear side, wherein
`said system includes a rectangular main body located
`behind said liquid crystal display board in a spaced
`relationship, said main body having a con?guration
`substantially identical to that of the liquid crystal dis
`play board and including;
`a single rectangular transparent substrate made of
`transparent resin,
`at ?rst coated layer deposited on the front surface of
`said transparent substrate with transparent resin,
`said ?rst coated layer having a refractive index
`different from that of the transparent substrate,
`a second coated layer deposited on the rear surface of
`the transparent substrate with transparent resin,
`said second coated layer having a refractive index
`different from that of the transparent substrate,
`a rugged layer deposited on the second coated layer
`with transparent resin suitably employable for
`forming an underlying layer, said rugged layer
`including a number of light reflecting means in the
`form of concavities and convexities on the front
`surface of said rugged layer for irregularly reflect
`ing light from each light source, said light reflect
`ing means being distributed with a density per unit
`area which increases in inverse proportion to a
`square of the distance as measured from each light
`source to keep brightness substantially uniform
`over the whole surface of the transparent substrate,
`and
`a plurality of light sources for generating light to be
`irradiated in the interior of the transparent sub
`strate.
`
`8
`2. The system as claimed in claim 1, wherein said
`light reflecting means are formed in a dot~shaped pat
`tern as viewed from the front side.
`3. The system as claimed in claim 1, wherein the said
`light reflecting means are formed in a straight line
`shaped pattern as viewed from the front side.
`4. The system as claimed in claim 1, wherein said
`plurality of light sources comprising a plurality of fluo
`rescent lamps, each one of said plurality of fluorescent
`lamps being arranged in the transparent substrate in a
`spaced relationship from the others of said plurality of
`?uorescent lamps.
`5. The system as claimed in claim 1, wherein said
`plurality of light sources comprising a plurality of fluo
`rescent lamps being arranged outside of the transparent
`substrate along four sides thereof.
`6. A system for uniformly illuminating a circular
`liquid crystal display board from the rear side, wherein
`said system includes a circular main body located be
`hind said liquid crystal display board in a spaced rela
`tionship, said main body having a con?guration substan
`tially identical to that of the liquid crystal display board
`and including;
`a single circular transparent substrate made of trans
`parent resin,
`a ?rst coated layer deposited on the front surface of
`said transparent substrate with transparent resin.
`said ?rst coated layer having a refractive indent
`different from that of the transparent substrate.
`a second coated layer deposited on the rear surface of
`the transparent substrate with transparent resin.
`said second coated layer having a refractive index
`different from that of the transparent substrate.
`a rugged layer deposited on the second coated layer
`with transparent resin suitably employable for
`forming an underlying layer, said rugged layer
`including a number of light reflecting means in the
`form of concavities and convexities on the front
`surface of the rugged layer for irregularly re?ect
`ing light from alight source, said light reflecting
`means being distributed with a density per unit area
`which increases in inverse proportion to a square of
`the distance as measured from said light source to
`keep brightness substantially uniform over the
`whole surface of the transparent substrate. and
`a single light source disposed at the central part of the
`transparent substrate for generating light to be
`irradiated in the interior of the transparent sub
`strate.
`7. The system as claimed in claim 6, wherein said
`light reflecting means are formed in a dot-shaped pat<
`tern as viewed from the front side.
`8. The system as claimed in claim 6», wherein said
`light re?ecting means are formed in a concentric circu
`lar line-shaped pattern as viewed from the front side.
`
`at
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`t
`
`a
`
`x
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`x
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`LGD_000704
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