(11) Japanese Unexamined Patent Application Publication No.
`6-242731
`(43) Publication Date: September 2, 1994
`(21) Application No. 5-051489
`(22) Application Date: February 17, 1993
`(71) Co-Applicant: Kuroda Electric Co., Ltd.
`(71) Co-Applicant: Shigetoshi SEKIYAMA
`(71) Co-Applicant: Midas Industry Co., Ltd.
`(72) Inventor: Mino et al.
`(74) Agent: Patent Attorney, Makoto KOHNO
`
`(54) [Title of the Invention] DISPLAY SURFACE BACKLIGHTING
`APPARATUS
`
`
`(57) [Abstract]
` [Object] An object is to provide a display surface
`backlighting apparatus that can keep display surface
`brightness uniform irrespective of a distance to a display
`plate such as a liquid crystal panel.
` [Construction] A display surface backlighting apparatus
`comprises: a light source holder 1; a groove 2 that is
`formed as a recessed peripheral surface of the light source
`holder 1; a light source 3 that is mounted in the groove 2;
`a light-guiding member 7 that has transparency to light and
`has a shape like a plate, a reflection surface 8 being
`
`- 1 -
`
`TOYOTA EXHIBIT 1005
`
`Page 1 of 12
`
`
`6-242731
`(43) Publication Date: September 2, 1994
`(21) Application No. 5-051489
`(22) Application Date: February 17, 1993
`(71) Co-Applicant: Kuroda Electric Co., Ltd.
`(71) Co-Applicant: Shigetoshi SEKIYAMA
`(71) Co-Applicant: Midas Industry Co., Ltd.
`(72) Inventor: Mino et al.
`(74) Agent: Patent Attorney, Makoto KOHNO
`
`(54) [Title of the Invention] DISPLAY SURFACE BACKLIGHTING
`APPARATUS
`
`
`(57) [Abstract]
` [Object] An object is to provide a display surface
`backlighting apparatus that can keep display surface
`brightness uniform irrespective of a distance to a display
`plate such as a liquid crystal panel.
` [Construction] A display surface backlighting apparatus
`comprises: a light source holder 1; a groove 2 that is
`formed as a recessed peripheral surface of the light source
`holder 1; a light source 3 that is mounted in the groove 2;
`a light-guiding member 7 that has transparency to light and
`has a shape like a plate, a reflection surface 8 being
`
`- 1 -
`
`TOYOTA EXHIBIT 1005
`
`Page 1 of 12
`
`
`
`formed at back of the light-guiding member 7, an end of the
`light-guiding member 7 being fixed inside the groove 2; and
`a light control plate 9 that is provided at a front-surface
`side of the light-guiding member 7 and is made of a film or
`a plate-like material serving as a light emission surface,
`wherein an irregular surface is formed at back of the light
`control plate 9; and wherein the irregular surface is an
`array 11 of convex portions and concave portions, which
`constitute a serrated shape in cross-sectional view.
`
`- 2 -
`
`Page 2 of 12
`
`
`
`[Claims]
`[Claim 1] A display surface backlighting apparatus,
`comprising:
`
`a light source holder (1);
`
`a groove (2) that is formed as a recessed peripheral
`surface of the light source holder (1);
`
`a light source (3) that is mounted in the groove (2);
`
`a light-guiding member (7) that has transparency to
`light and has a shape like a plate, a reflection surface (8)
`being formed at back of the light-guiding member (7), an end
`of the light-guiding member (7) being fixed inside the
`groove (2); and
`
`a light control plate (9) that is provided at a front-
`surface side of the light-guiding member (7) and is made of
`a film or a plate-like material serving as a light emission
`surface,
`
`wherein an irregular surface is formed at back of the
`light control plate (9).
`[Claim 2] The display surface backlighting apparatus
`according to Claim 1, wherein the irregular surface is an
`array (11) of convex portions and concave portions, which
`constitute a serrated shape in cross-sectional view.
`[Claim 3] The display surface backlighting apparatus
`according to Claim 1, wherein an inner surface of the groove
`(2) is formed as a reflection surface.
`
`- 3 -
`
`Page 3 of 12
`
`
`
`[Detailed Description of the Invention]
`[0001]
`[Field of Industrial Application] The present invention
`relates to a backlight apparatus for applying light to a
`liquid crystal display surface, a photo film / drawing see-
`through plate, etc. for illumination from behind.
`[0002]
`[Description of the Related Art] As an apparatus for
`backlighting a display surface in a liquid crystal display
`plate, a see-through plate, etc., a device that is an
`assembled combination of the following components has been
`known in the art. A light-guiding plate 7, which is made of
`an acrylic plate or the like, is mounted in/on a light
`source holder 1, on which a light source 3 made up of plural
`light emission elements (LED), etc. as illustrated in Figs.
`3 and 4 is fixed. A light-diffusing plate (not shown) is
`provided at the front-surface side of the light-guiding
`plate 7, with a predetermined clearance left therebetween.
`[0003]
`[Problems to be Solved by the Invention] The prior-art
`example described above has the following disadvantages.
`Brightness decreases gradually from the base edge of the
`light-guiding plate 7, that is, an edge that is closer to
`the light source 3, toward the opposite edge, resulting in
`the lack of uniformity in brightness. Between the base edge
`
`- 4 -
`
`Page 4 of 12
`
`
`
`and the center of the light-guiding plate 7, there are
`differences between the brightness of illuminated areas 5a
`corresponding to the respective light-source elements 3, the
`brightness of non-illuminated areas 5b, which are areas
`where no light is applied, and the brightness of overlapping
`illuminated areas 5c, which are areas where respective beams
`emitted from adjacent light-source elements 3 overlap. The
`brightness differences cause irregularities as a whole;
`therefore, it is not possible to ensure uniformity in
`brightness throughout the entire display surface. In order
`to improve uniformity in brightness over the display surface,
`it is necessary to install a liquid crystal panel at a
`sufficient distance from the light-guiding plate 7 of the
`backlight apparatus. This increases not only the thickness
`of the backlight apparatus but also cost inefficiently so as
`to ensure sufficient light-source brightness.
`[0004]
`[Means for Solving the Problems] In order to solve the
`above problems, as a first feature of the present invention,
`a display surface backlighting apparatus comprises: a light
`source holder 1; a groove 2 that is formed as a recessed
`peripheral surface of the light source holder 1; a light
`source 3 that is mounted in the groove 2; a light-guiding
`member 7 that has transparency to light and has a shape like
`a plate, a reflection surface 8 being formed at back of the
`
`- 5 -
`
`Page 5 of 12
`
`
`
`light-guiding member 7, an end of the light-guiding member 7
`being fixed inside the groove 2; and a light control plate 9
`that is provided at a front-surface side of the light-
`guiding member 7 and is made of a film or a plate-like
`material serving as a light emission surface, wherein an
`irregular surface is formed at back of the light control
`plate 9. A second feature is that the irregular surface is
`an array 11 of convex portions and concave portions, which
`constitute a serrated shape in cross-sectional view. A
`third feature is that an inner surface of the groove 2 is
`formed as a reflection surface.
`[0005]
`[Operation] Light projected into a light-guiding plate 7
`from a light source 3 gets refracted and reflected
`repeatedly inside the light-guiding plate 7 by impinging on
`an irregular surface or a reflection surface 8, or directly,
`and is finally oriented by furrows 11 to pass through a
`light control plate 9 to exit toward the front
`perpendicularly to the light control plate 9, with uniform
`brightness, for illumination at the front side of the light
`control plate 9. Therefore, even when a display plate such
`as a liquid crystal panel is installed at the front-surface
`side of the light control plate 9, it is possible to keep
`display surface brightness uniform irrespective of a
`distance to the display plate.
`
`- 6 -
`
`Page 6 of 12
`
`
`
`[0006]
`[Embodiment] The illustrated embodiment will now be
`explained in detail. A light source holder 1 (overall
`length: 60 mm) is made of white polycarbonate, etc. and has
`a shape like a square bracket or turned U in cross-sectional
`view. A recessed groove portion 2, which extends from one
`end to the opposite end in the length direction of the light
`source holder 1, is formed in the light source holder 1.
`Plural light emission elements (light source) 3 such as LEDs
`are provided inside the groove 2. Each of the light mission
`elements 3 is connected to an electric wire 6, which is
`inserted in and through a hollow guide member 4. The hollow
`guide member 4 is attached to the outer side face of the
`light source holder 1.
`[0007]
`
`A light-guiding plate 7 (thickness: 1.5 mm), which is
`made of a transparent acrylic plate and has a rectangular
`shape (60 mm × 20 mm) in plan view, is fitted in the groove
`2 of the light source holder 1. A reflection surface 8 is
`formed at the back of the light-guiding plate 7 by applying
`a reflective paint thereto or by coating the back surface
`with a reflective sheet.
`[0008]
`
`A guided-light exit control plate 9 (thickness: 0.6 mm),
`which has the same rectangular shape (60 mm × 20 mm) as that
`
`- 7 -
`
`Page 7 of 12
`
`
`
`of the light-guiding plate 7 in plan view, is provided on a
`surface of the light-guiding plate 7. The light control
`plate 9 is a lens film or a plate made of transparent resin.
`The peripheral frame region of the light control plate 9 is
`fixed to the light-guiding plate 7 by fusion bonding. The
`light control plate 9 has an alternate array 11 of
`ridge/convex portions and valley/concave portions, at its
`back. The furrows 11 constitute a serrated shape in cross-
`sectional view. The furrows 11 have a depth of 0.05 to 0.1
`mm and an array pitch of 0.1 to 0.2 mm. The sectional shape
`of each ridge and each valley is an isosceles triangle
`having a vertex angle of 90°. The furrows 11 extend in
`parallel to the length-directional side edges. A light-
`diffusing plate 13 made of a liquid crystal plate or the
`like is provided over and in parallel to the light control
`plate 9 of the body 12 of the backlight apparatus.
`[0009]
`
`In the above structure, light is emitted from the light
`emission elements 3 into the light-guiding plate 7, and the
`refraction and reflection of the light by the furrows 11 at
`the back of the light control plate 9 and the reflection of
`the light by the reflection surface 8 at the bottom 7b of
`the light-guiding plate 7 are repeated. The light control
`plate 9 allows the reflected light coming from the
`reflection surface 8 to pass through itself toward the
`
`- 8 -
`
`Page 8 of 12
`
`
`
`diffusion plate 13 at a right angle uniformly throughout the
`entire surface. Consequently, with the above structure, the
`display surface of the diffusion plate 13 is illuminated
`with the light uniformly from behind, and the uniform back
`illumination realizes a uniform light emission display
`surface that is free from brightness irregularities.
`Therefore, the diffusion plate 13 may be mounted in contact
`with the front surface of the light control plate 9.
`[0010]
`
`In the above structure, preferably, for the purpose of
`preventing the leakage of light to the outside through the
`peripheral surface of the light-guiding plate 7, the
`reflection surface 8 should be formed not only at the back
`but also at the peripheral surface of the light-guiding
`plate 7 by applying a reflective paint thereto or by bonding
`a reflective sheet thereto. For condensed orientation,
`toward the front, of light emitted from the light source 3,
`preferably, the reflection surface 8 should be formed
`additionally at both sides next to each light emission
`element 3 inside the groove 2 in the same manner as above.
`If a white material is chosen for the light source holder 1
`as in the present embodiment, however, the inner surface of
`the groove 2 of the light source holder 1 itself serves as a
`reflection surface. A single light source holder 1 provided
`at one side of the light-guiding plate 7 suffices for a
`
`- 9 -
`
`Page 9 of 12
`
`
`
`diffusion plate 13 of ordinary size. If the diffusion plate
`13 is large, another light source holder 1 may be added at
`the opposite side as indicated by a phantom line in Fig. 2
`for emission from both sides.
`[0011]
`
`We conducted an experiment on backlighting effects by
`using structures illustrated in Figs. 5(A), 5(B), and 5(C)
`as comparative examples for the assembled structure of the
`light source holder 1, the light-guiding plate 7, and the
`light control plate 9 according to the present invention,
`and found that the performance of the structure of the
`embodiment illustrated in Fig. 2 is superior to the
`performance of all of the structures illustrated in Figs.
`5(A), 5(B), and 5(C) both in terms of brightness level and
`in terms of uniformity. This is probably because, firstly,
`it is possible to project light farther into the light-
`guiding plate 7 if the projection is from inside a narrow
`groove 2 at an end of the light-guiding plate 7, and,
`secondly, the inner walls of the groove 2 produces
`reflection effects.
`[0012]
`[Advantages] Compared with an apparatus according to prior
`art, an apparatus according to the present invention, an
`exemplary structure of which is described above, makes it
`possible to obtain a wider light emission surface because
`
`- 10 -
`
`Page 10 of 12
`
`
`
`light reaches a position in a light-guiding plate away from
`a light source. Another advantage is that it is possible to
`prevent brightness irregularities over a light emission
`surface, resulting in uniform luminosity. Therefore, if
`applied to a liquid crystal display surface, the invention
`makes it possible to mount a liquid crystal plate in contact
`with a light control plate, thereby reducing the thickness
`of a backlight portion and the overall thickness of
`equipment provided with the backlight.
`[Brief Description of the Drawings]
`[Fig. 1] Fig. 1(A) is a side view of a backlight apparatus,
`and Fig. 1(B) is a plan view thereof;
`[Fig. 2] Fig. 2 is an enlarged sectional view of a
`backlight apparatus according to an exemplary embodiment of
`the present invention;
`[Fig. 3] Fig. 3 is an enlarged perspective view that
`illustrates the structure of a light source holder;
`[Fig. 4] Fig. 4 is a plan view that illustrates the
`brightness distribution of backlight apparatus according to
`prior art; and
`[Fig. 5] Each of Figs. 5(A), 5(B), and 5(C) is a sectional
`view that illustrates a failure example of the present
`invention.
`[Reference Numerals]
`1 light source holder
`
`- 11 -
`
`Page 11 of 12
`
`
`
`2 groove
`3 light source
`7 light-guiding plate
`8 reflection surface
`9 light control plate
`11 furrow
`13 diffusion plate
`
`- 12 -
`
`Page 12 of 12
`
`
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