United States Patent [19]
`Noguchi et al.
`
`111111111111111111111111111111111111111111111111111111111111111111111111111
`US005497293A
`[11] Patent Number:
`[45] Date of Patent:
`
`5,497,293
`Mar. 5, 1996
`
`[54] SURFACE ILLUMINANT DEVICE
`
`5,335,100
`
`8/1994 Obata ........................................ 362/27
`
`[75]
`
`Inventors: Nobuhisa Noguchi, Ohmiya; Jun
`Tamaki, Kawaguchi, both of Japan
`
`[73] Assignee: Enplas Corporation, Japan
`
`[21] Appl. No.:
`
`244,673
`
`[22] PCT Filed:
`
`Apr. 22, 1994
`
`[86] PCTNo.:
`
`PCT/JP94/00675
`
`§ 371 Date:
`
`Jun.7,1994
`
`§ 102(e) Date: Jun. 7, 1994
`Int. Cl.6
`........................................................ F21V 8/00
`[51]
`[52] U.S. Cl ............................... 362/31; 362/26; 362/330;
`362/457
`[58] Field of Search .................................. 362/26, 27, 31,
`362/330, 457, 257
`
`[56]
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`3,132,810
`4,918,578
`5,050,046
`5,150,960
`5,211,464
`
`5/1964 Ostensen ................................... 362/31
`4/1990 Thompson ................................ 362/31
`911991 Tada .......................................... 362131
`9/1992 Redick ...................................... 362131
`5/1993 Bohmer ..................................... 362/31
`
`FOREIGN PATENT DOCUMENTS
`
`5-297813 1111993
`Japan .
`786576 1111957 United Kingdom ..................... 362/31
`
`Primary Examiner-Ira S. Lazarus
`Assistant Examiner-Alan B. Cariaso
`Attorney, Agent, or Firm-Graham & James
`ABSTRACT
`[57]
`
`A surface illuminant device which is usable as a backlight
`for liquid crystal display units and does not allow a light
`diffusing sheet 2 or a reflecting sheet 4 to be slackened due
`to variations of temperature and humidity. Collars 6a and 6b
`of a holder 6 are disposed on surfaces of a light transmitter
`1 opposed to each other so that a gap slightly larger than
`thickness of the light diffusing sheet 2 is formed between the
`collar 6a of the holder 6 and a surface of emergence 1a of
`the light transmitter 1, and a gap slightly larger than thick(cid:173)
`ness of the reflecting sheet is formed between the surface 1b
`opposed to the surface of emergence 1a of the light trans(cid:173)
`mitter 1 for allowing ends of the light diffusing sheet and the
`reflecting sheet to be freely movable within a predetermined
`range in the gaps, whereas the other ends of the light
`diffusing sheet and the reflecting sheet are fixed to the light
`transmitter 1 by fixing means 3, 5, 10 and 14.
`
`11 Claims, 2 Drawing Sheets
`
`8
`
`6
`
`TOYOTA EXHIBIT 1013
`
`Page 1 of 7
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`

`
`U.S. Patent
`
`Mar. 5, 1996
`
`Sheet 1 of 2
`
`5,497,293
`
`FIG. 1
`8
`
`6
`
`FIG. 2
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`11
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`/
`
`2
`
`1
`
`6b
`
`4
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`Page 2 of 7
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`

`
`U.S. Patent
`
`Mar. 5, 1996
`
`6 6a' 8 6a"
`
`Sheet 2 of 2
`FIG. 3
`
`5,497,293
`
`ld
`
`FIG. 4
`
`6
`
`8
`
`2 a-~~~~~ /'l~r4-1~4-L-~~~~~~ ,....,......,.-;:::;;~
`1c
`
`13
`
`FIG. 5
`
`6
`
`8 2b
`
`FIG. 6
`
`6 12
`
`8
`
`1
`
`4b
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`Page 3 of 7
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`

`
`5,497,293
`
`1
`SURFACE ILLUMINANT DEVICE
`
`TECHNICAL FIELD
`
`The present invention relates to a surface illuminant
`device to be used, for example, as a backlight for liquid
`crystal display units, and more specifically a surface illumi(cid:173)
`nant device which uses a light transmitter.
`
`BACKGROUND ART
`
`2
`For solving this problem, it has conventionally been
`practised to dispose the light diffusing sheet 2 and the
`reflecting sheet 4 in a condition where opposite ends of the
`light diffusing sheet 2 and the reflecting sheet 4 are kept free
`5 or not fixed. When the light diffusing sheet 2 and the
`reflecting sheet 4 are disposed in such a condition, however,
`the light diffusing sheet 2 and/or the reflecting sheet 4 may
`tear off the surface of emergence 1a of the light transmitter
`1 under certain kinds of circumstances, thereby allowing
`10 dust or foreign matters to enter a gap and/or gaps formed
`between the light diffusing sheet 2 and the surface of
`emergence 1a of the light transmitter 1 and/or between the
`surface of emergence 1a of the light transmitter 1 and the
`reflecting sheet 4 before the surface illuminant device is
`15 built into a casing. The dust or the foreign matters intercept
`the rays which are to emerge from the surface of emergence
`1a of the light transmitter 1, thereby lowering luminance on
`the surface illuminant device.
`In view of the problem described above, it is a primary
`20 object of the present invention to provide a surface illumi(cid:173)
`nant device which is configured so as to prevent the light
`diffusing sheet and the reflecting sheet from tearing off the
`light transmitter, and allows no dust or foreign matter to
`enter between the light transmitter and either of these sheets
`25 without fixing an end thereof.
`Another object of the present invention is to provide a
`surface illuminant device which is composed of parts in a
`number smaller than that of the parts required for composing
`the conventional surface illuminant device and can be
`assembled more easily than the conventional surface illu(cid:173)
`minant device.
`
`DISCLOSURE OF INVENTION
`
`In the surface illuminant device according to the present
`invention, the collars of the holder are disposed facing
`respective surfaces of the light transmitter opposed to each
`other so as to leave a gap slightly larger than thickness of the
`light diffusing sheet and a gap slightly larger than the
`thickness of the reflecting sheet respectively between one of
`the collars of the holder and the surface of emergence of the
`light transmitter and between the other collar of the holder
`and the surface of the light transmitter opposed to the surface
`of emergence, and ends of the light diffusing sheet and the
`reflecting sheet near the holder are respectively arranged in
`the gaps so as to be allows to move within a predetermined .
`range, and the opposite ends of the light diffusing sheet and
`the reflecting sheet are fixed to the light transmitter by fixing
`means. Accordingly, the ends of the light diffusing sheet and
`the reflecting sheet near the holder are freely movable
`relative to the light transmitter and cannot be slackened even
`when the light diffusing sheet, the light transmitter and the
`reflecting sheet are expanded or contracted at different ratios
`due to variations of temperature and/or humidity.
`Further, a tip of a bolt which is to be used for fixing the
`collars of the holder to the light transmitter is screwed
`directly to one of the collars. Thus, the surface illuminant
`device according to the present invention requires no nut atld
`can be assembled in simple procedures.
`
`BRIEF DESCRIPTION OF DRAWINGS
`
`FIG. 1 is a sectional view exemplifying a conventional
`surface illuminant device using a light transmitter;
`FIG. 2 is a perspective View illustrating main parts of an
`embodiment of the surface illuminant device according to
`the present invention in a disassembled condition thereof;
`
`FIG. 1 is a sectional view exemplifying a conventional
`surface illuminant device using the light transmitter. In this
`drawing, the reference numeral 1 represents a rectangular
`plate-like light transmitter having adequate thickness and a
`proper area; 2 is a light diffusing sheet mounted on a surface
`of emergence 1a of the light transmitter 1 in a condition
`where one end of the light diffusing sheet 2 is fixed, for
`example, with a double-adhesive tape 3 and having an area
`substantially the same as that of the light transmitter 1; and
`4 is a reflecting sheet mounted on a surface 1b of the light
`transmitter 1 which is opposite to the surface of emergence
`1a in a condition where one end of the reflecting sheet 4 is
`fixed, for example, with a double-adhesive tape 5 and having
`an area substantially the same as that of the light transmitter
`1. The reference numeral 6 designates a holder which has
`collars 6a and 6b sandwiching opposite ends of the light
`transmitter 1, the light diffusing sheet 2 and the reflecting
`sheet 4, extends along an end surface of incidence 1c of the 30
`light transmitter 1 so as to cover the ends of the light
`transmitter 1, the light diffusing sheet 2 and the reflecting
`sheet 4 and has a substantially toric sectional shape; and 7
`is a slender light source such as a cold cathode ray tube
`which is fixed to the holder 6 by an adequate means and 35
`extends along the surface of incidence 1c of the light
`transmitter 1. The reference numeral 8 denotes a bolt
`inserted through holes which are coaxially bored through the
`collar 6a, the light diffusing sheet 2, the light transmitter 1,
`the reflecting sheet 4 and the collar 6b; and 9 is a nut which 40
`is screwed around an end of the bolt 8 protruding from a
`bottom surface of the collar 6b.
`In the surface illuminant device which is configured as
`described above, rays emitted from the light source 7 travel
`toward the end surface of incidence 1c directly from the light
`source 7 or after being reflected by a reflecting surface
`formed as an inside surface of the holder 6, enter the light
`transmitter 1 from the end surface of incidence 1c and
`propagate through the light transmitter 1. In the light trans(cid:173)
`mitter 1, the incident rays are reflected by the reflecting sheet
`4 or inside surfaces of the light transmitter 1, thereafter
`emerging from the surface of emergence 1a. Since the rays
`are diffused by the light diffusing sheet 2 while transmitting
`therethrough, this surface of the light diffusing sheet 2 can
`be used as a surface light source.
`Such a surface illuminant device may ordinarily be used
`in environments kept at high temperature or high humidity.
`When the conventional surface illuminant device is used in
`such environments, the light transmitter 1, the light diffusing
`sheet 2 and the reflecting sheet 4 which have coefficients of 60
`linear expansion different from one another are expanded or
`contracted at ratios different from one another, whereby the
`light diffusing sheet 2 and/or the reflecting sheet 4 may be
`slackened. In such a case, the rays emerging from the surface
`of emergence 1a of the light transmitter 1 are influenced so 65
`as to constitute a cause for an ununiform luminance distri(cid:173)
`bution on the surface illuminant device.
`
`45
`
`50
`
`55
`
`Page 4 of 7
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`

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`5,497,293
`
`3
`FIG. 3 is a sectional view illustrating main parts of the
`surface illuminant device shown in FIG. 2 in an assembled
`condition thereof;
`FIG. 4 is a sectional view illustrating main parts of
`another embodiment of the surface illuminant device 5
`according to the present invention;
`FIG. 5 is a sectional view illustrating main parts of still
`another embodiment of the surface illuminant device
`according to the present invention; and
`FIG. 6 is a sectional view illustrating main parts of a still
`further embodiment of the surface illuminant device accord-
`ing to the present invention.
`
`10
`
`BEST MODE FOR CARRYING OUT THE
`INVENTION
`
`30
`
`4
`into the notches 2a and 4a respectively, and the run-through
`holes 6a", the run-through holes 1d bored through the light
`transmitter 1 and the tapped holes 6b" are aligned with one
`another. The bolts 8 are inserted from above through the
`run-through holes 6a" and 1d, and screwed into the tapped
`hole 6b" for fixing the holder 6 to the light transmitter 1. The
`temporary fixing by the thermal welding or with the double(cid:173)
`adhesive tapes 11 is done to prevent the light diffusing sheet
`2 and the reflecting sheet 4 from tearing off the surfaces of
`the light transmitter 1 during the assembly works since gaps
`formed by slackening of the sheets may allow dust or foreign
`matters to enter between the light transmitter 1 and the
`sheets or constitute a cause for contamination of the light
`diffusing sheet 2 with fingerprints. Further, the temporary
`fixing is made at extremely narrow areas so that the light
`15 diffusing sheet 2 and the reflecting sheet 4 can easily be
`peeled off the light transmitter 1 when, after the assembly
`process, changes in temperature or humidity expand or
`contract these sheets be displaced relative to the light
`transmitter 1 in the direction indicated by the arrow A or B
`20 shown in FIG. 2. It is general that the light transmitter 1 is
`made of a methacrylic resin, the light diffusing sheet is made
`of polycarbonate and the reflecting sheet 4 is made of an
`expanded material mainly consists of polyethylene tereph(cid:173)
`thalate. The methacrylic resin is expanded or contracted
`25 much more remarkably than polycarbonate or polyethylene
`terephthalate due to humidity variations.
`The first embodiment of the surface illuminant device
`according to the present invention, which has the configu(cid:173)
`ration described above, allows the light diffusing sheet 2 and
`the reflecting sheet 4 to move freely relative to the light
`transmitter 1 in the directions indicated by the arrows A and
`B in FIG. 2 when the light transmitter 1, the light diffusing
`sheet 2 and the reflecting sheet 4 are expanded or contracted
`at different ratios due to variations of temperature and
`35 humidity. Accordingly, the light diffusing sheet 2 and the
`reflecting sheet 4 which are rigid to certain degrees cannot
`be slackened. Further, the light diffusing sheet 2 and the
`reflecting sheet 4 which are kept in the conditions where
`they are fitted in the collars 6a and 6b respectively with
`40 narrow gaps cannot slip out of the collars. As a result,
`variations of temperature and humidity cannot constitute
`causes for ununiform luminance distributions on the surface
`illuminant device preferred as the first embodiment of the
`present invention.
`FIG. 4 shows a second embodiment of the surface illu(cid:173)
`minant device according to the present invention. In the
`second embodiment, which is different from the first
`embodiment in some points, the protrusions 6a' and 6b' are
`formed as washers 12 and 13 respectively which are separate
`from the collars 6a and 6b, the tip of the bolt 8 is screwed
`to the collar 6b only, and the light transmitter 1, the light
`diffusing sheet 2 and the reflecting sheet 4 are integrally
`fixed with a plastic rivet 14. Functions and effects of the
`second embodiment are substantially the same as those of
`the first embodiment, and will not be described in particular.
`FIG. 5 illustrates a third embodiment of the surface
`illuminant device according to the present invention. In the
`third embodiment which is different from the second
`embodiment only in one point, the light diffusing sheet 2 and
`the reflecting sheet 4 are preliminarily mounted on the light
`transmitter 1 so that they have edges at locations at a
`predetermined distance from the washers 12 and 13 respec(cid:173)
`tively on the side of the holder 6. Functions and effects of the
`third embodiment will not be described in particular since
`they are substantially the same as those of the first embodi(cid:173)
`ment and the second embodiment which have already been
`described above.
`
`Now, the present invention will be described in detail
`below with reference to the preferred embodiments illus(cid:173)
`trated in the accompanying drawings using the reference
`numerals of the parts of the conventional surface illuminant
`device described above for members and parts of the surface
`illuminant device according to the present invention which
`are the same or substantially the same as those of the
`conventional surface illuminant device.
`In the first embodiment of the present invention, formed
`on an inside surface of the collar 6a of the holder 6 is a
`washer-like protrusion 6a' integrally with the collar 6a and
`a run-through hole 6a" is bored through the collar 6a and the
`protrusion 6a' as shown in FIGS. 2 and 3. Further, formed on
`the inside surface of the collar 6b of the holder 6 is a
`washer-like protrusion 6b' integrally with the collar 6b, and
`a tapped hole 6b" is bored in the protrusion 6b' and the collar
`6b. The run-through hole 6a" is aligned with the tapped hole
`6b" in a direction perpendicular to the planar surface of the
`light transmitter 1. This pair of the protrusion 6a' having the
`run-through hole and the protrusion 6b' having the tapped
`hole is formed actually in a plurality at predetermined
`intervals in a longitudinal direction of the collars 6a and 6b.
`On the side near the holder 6, there are formed notches 2a,
`for example in a semicircular shape which can loosely fit
`around the protrusions 6a' and 6b' of the holder 6, in an edge
`of the light diffusing sheet 2 at locations corresponding to
`the protrusions. Similar notches 4a are formed also in an
`edge of the reflecting sheet 4. As seen from FIG. 3, the 45
`protrusions 6a' and 6b' have heights which are a little larger
`than thickness of the light diffusing sheet 2 and that of the
`reflecting sheet 4 respectively. The reference numeral 10
`(used in FIG. 3) represents a clip which is used for integrally
`fixing the opposite ends which are farther from the holder 6, 50
`of the light transmitter 1, the light diffusing sheet 2 and the
`reflecting sheet 4.
`Now, description will be made of procedures to assemble
`the surface illuminant device preferred as the first embodi(cid:173)
`ment described above.
`First, the light diffusing sheet 2 and the reflecting sheet 4
`are mounted on the surfaces of the light transmitter 1 which
`are opposite to each other, and the light transmitter and these
`sheets which make a layered structure, are integrally fixed
`by using the clip 10 at a portion on this layered structure. 60
`The light diffusing sheet 2 and the reflecting sheet 4 are
`temporarily fixed to the light transmitter 1 by thermal
`welding or with double-adhesive tapes 11 at the opposite end
`of the layered structure as schematically shown in FIG. 2.
`Then, the holder 6 is set so as to sandwich the light diffusing 65
`sheet 2 and the reflecting sheet 4 between the collars 6a and
`6b, and adjusted so that the protrusions 6a' and 6b' are fitted
`
`55
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`Page 5 of 7
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`

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`5,497,293
`
`5
`FIG. 6 shows a fourth embodiment of the surface illumi(cid:173)
`nant device according to the present invention. In the fourth
`embodiment which is different from the second embodiment
`or the third embodiment only in one point, openings 2c and
`4c which are larger by a predetermined value in diametrical 5
`length than the washers 12 and 13 are formed in the end of
`the light diffusing sheet 2 and the reflecting sheet 4 respec(cid:173)
`tively on the side near the holder 6. Functions and effects of
`the fourth embodiment are substantially the same as those of
`the embodiments already described above and will not be 10
`described in particular.
`The ends of the light transmitter 1, the light diffusing
`sheet 2 and the reflecting sheet 4 which are located on the
`side opposite to the holder 6 can be fixed with an adequate
`mechanical means such as a screw in place of the double(cid:173)
`adhensive tapes 3 and 5 or the thermal welding adopted for
`the embodiments described above. Though the run-through
`holes and the tapped holes are bored in the collars 6a and 6b
`respectively for inserting the bolts 8 from above in the
`embodiments described above, it is possible to bore the
`tapped holes and the run-through holes in the collars 6a and
`6b respectively so that the bolts 8 can be inserted from down
`side.
`Further, it is possible to select an adequate combination of
`the manners of the embodiments described above which are 25
`selected for disposing the ends of the light transmitter 1, the
`light diffusing sheet 2 and the reflecting sheet 4 so that the
`light diffusing sheet 2 and the reflecting sheet 4 are movable
`relatively to the light transmitter 1 between the collars 6a
`and 6b on the side of the holder 6.
`Fundamental functions of the surface illuminant devices
`preferred as the embodiments of the present invention are
`substantially the same as those of the conventional surface
`illuminant device and will not be explained in particular.
`
`35
`
`INDUSTRIAL APPLICABILITY
`
`30
`
`6
`ing sheet located in said second end zone being laid
`respectively underneath said upper end portion and said
`lower end portion, with respective minimum spaces
`kept between said upper end portion of said holder and
`said light diffusing sheet and between said lower end
`portion of said holder and said reflecting sheet for
`allowing movement of said light diffusing sheet and
`said reflecting sheet relative to said light transmitter in
`directions along the upper side and lower side surfaces
`of said light transmitter except at said portion fixed by
`said fixing means.
`2. A surface illuminant device according to claim 1
`wherein said fixing means consists of a double-adhesive tape
`interposed between said light transmitter and said light
`diffusing sheet, and another double-adhesive tape interposed
`15 between said light transmitter and said reflecting sheet.
`3. A surface illuminant device according to claim 1
`wherein said fixing means is a clip or a plastic rivet.
`4. A surface illuminant device according to claim 1 or 2
`wherein said upper end portion and said lower end portion
`20 of said holder are formed as a pair of collars comprising an
`upper collar and a lower collar for sandwiching said layered
`structure, and
`wherein said attaching means comprises a plurality of
`upper protrusions formed on said upper collar inte(cid:173)
`grally therewith or separately therefrom having a height
`larger than the thickness of said light diffusing .sheet
`and having run-through holes bored therein so as to be
`placed on said layered structure, a plurality of lower
`protrusions formed on said lower collar integrally
`therewith or separately therefrom having a height larger
`than the thickness of said reflecting sheet and having
`tapped holes bored therein and disposed opposite said
`upper protrusions on said layered structure, and a
`plurality of bolts inserted through said upper protru(cid:173)
`sions utilizing the run-through holes bored therein and
`through said light transmitter, and screwed to said
`lower protrusions utilizing the tapped holes bored
`therein, and
`wherein a plurality of notches are formed on said light
`diffusing sheet and said reflecting sheet in said second
`end zone so as to be aligned with said upper protrusions
`and said lower protrusions, said upper protrusions and
`said lower protrusions being respectively surrounded
`loosely and at least partially by respective border edges
`of said light diffusing sheet and said reflecting sheet, so
`that said light diffusing sheet and said reflecting sheet
`with which said notches are bordered have no contact
`with said upper protrusions and said lower protrusions
`respectively.
`5. A surface illuminant device according to claim 1 or 2
`wherein said upper end portion and said lower end portion
`of said holder are formed as a pair of collars, comprising an
`upper collar and a lower collar for sandwiching said layered
`55 structure,
`wherein said attaching means comprises a plurality of
`upper protrusions formed on said upper collar inte(cid:173)
`grally therewith or separately therefrom having a height
`larger than the thickness of said light diffusing sheet
`and having tapped holes bored therein so as to be
`placed on said layered structure, a plurality of lower
`protrusions formed on said lower collar integrally
`therewith or separately therefrom having a height larger
`than the thickness of said reflecting sheet and having
`run-through holes bored therein and disposed opposite
`said upper protrusions, on said layered structure, and a
`plurality of bolts inserted through said lower protru-
`
`45
`
`50
`
`As understood from the foregoing description, the surface
`illuminant device according to the present invention is 40
`effectively useful as a backlight for liquid crystal display
`units.
`What is claimed is:
`1. A surface illuminant device comprising:
`a light source;
`a light transmitter having an incident end face disposed in
`a vicinity of said light source;
`a holder accommodating said light source and serving for
`condensing rays emitted from said light source onto
`said incident end face of said light transmitter;
`a light diffusing sheet mounted on an upper side surface
`of said light transmitter; and
`a reflecting sheet disposed on a lower side surface of said
`light transmitter,
`wherein a layered structure .consisting of said light trans(cid:173)
`mitter, said light diffusing sheet and said reflecting
`sheet, is integrally fixed by fixing means at a portion of
`a first end zone of said layered structure opposite to said
`incident end face, and
`wherein said holder is attached to said layered structure
`by a plurality of attaching means in such a manner that
`a second end zone of said layered structure opposite to
`said first end zone and including said incident end face
`of said light transmitter is enclosed between an upper 65
`end portion and a lower end portion of said holder, with
`end edges of said light diffusing sheet and said reflect-
`
`60
`
`Page 6 of 7
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`5,497,293
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`15
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`7
`sions utilizing the run-through holes bored therein and
`through said light transmitter, and screwed to said
`upper protrusions utilizing the tapped holes bored
`therein, and
`wherein a plurality of notches are formed on said light 5
`diffusing sheet and said reflecting sheet in said second
`end zone so as to be aligned with said upper protrusions
`and said lower protrusions, said upper protrusions and
`said lower protrusions being respectively surrounded
`loosely and at least partially by respective border edges
`of said light diffusing sheet and said reflecting sheet
`with which said notches are bordered, so that said light
`diffusing sheet and said reflecting sheet have no contact
`with said upper protrusions and said lower protrusions
`respectively.
`6. A surface illuminant device according to claim 4
`wherein said notches are holes separated from the end edges
`of said light diffusing sheet and said reflecting sheet.
`7. A surface illuminant device according to claim 4
`wherein said notches are concavities cut from the end edges 20
`of said light diffusing sheet and said reflecting sheet in said
`second end zone.
`8. A surface illuminant device according to claim 1 or 2
`wherein said upper end portion and said lower end portion
`of said holder are formed as a pair of collars comprising an 25
`upper collar and a lower collar for sandwiching said layered
`structure,
`wherein said attaching means comprises a plurality of
`upper protrusions formed on said upper collar inte(cid:173)
`grally therewith or separately therefrom having a height 30
`larger than the thickness of said light diffusing sheet
`and having run-through holes bored therein so as to be
`placed on said layered structure, a plurality of lower
`protrusions formed on said lower collar integrally
`therewith or separately therefrom having a height larger 35
`than the thickness of said reflecting sheet and having
`tapped holes bored therein so as to be placed, opposite
`said upper protrusions, on said layered structure, and a
`plurality of bolts inserted through said upper protru(cid:173)
`sions utilizing the run-through holes bored therein and 40
`through said light transmitter, and screwed to said
`lower protrusions utilizing the tapped holes bored
`therein, and
`
`8
`wherein said light diffusing sheet and said reflecting sheet
`are disposed so that the respective end edges thereof in
`said second end zone are located more inwardly than
`said upper protrusions and said lower protrusions on
`the upper side and lower side surfaces of said light
`transmitter.
`9. A surface illuminant device according to claim 1 or 2
`wherein said upper end portion and said lower end portion
`of said holder are formed as a pair of collars comprising an
`10 upper collar and a lower collar for sandwiching said layered
`structure,
`wherein said attaching means consist of a plurality of
`upper protrusions formed on said upper collar inte(cid:173)
`grally therewith or separately therefrom having a height
`larger than the thickness of said light diffusing sheet
`and having tapped holes bored therein so as to be
`placed on said layered structure, a plurality of lower
`protrusions formed on said lower collar integrally
`therewith or separately therefrom having a height larger
`than the thickness of said reflecting sheet and having
`run-through holes bored therein so as to be placed,
`opposite said upper protrusions, on said layered struc(cid:173)
`ture, and a plurality of bolts inserted through said lower
`protrusions utilizing the run-through holes bored
`therein and through said light transmitter, and screwed
`to said upper protrusions utilizing the tapped holes
`bored therein, and
`wherein said light diffusing sheet and said reflecting sheet
`are disposed so that the respective end edges thereof in
`said second end zone are located more inwardly than
`said upper protrusions and said lower protrusions on
`the upper side and lower side surfaces of said light
`transmitter.
`10. A surface illuminant device according to claim 5
`wherein said notches further comprise holes separated from
`the end edges of said light diffusing sheet and said reflecting
`sheet.
`11. A surface illuminant device according to claim 5
`wherein said notches further comprise concavities cut from
`the end edges of said light diffusing sheet and said reflecting
`sheet in said second end zone.
`
`* * * * *
`
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