1
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`(11) Japanese Patent Laid-Open No. Hei 4-278922
`(43) Japanese Patent Laid-Open Date: October 5, 1992
`(21) Japanese Patent Application No. Hei 3-68068
`(22) Japanese Patent Application Date: March 7, 1991
`(71) Applicant: 000190116
`Shin-Etsu Polymer Co., Ltd.
`4-3-5, Nihonbashi-Honcho, Chuo-ku, Tokyo
`(72) Inventor: Tsutomu SUZUKI
`c/o Product Research Center
`Shin-Etsu Polymer Co., Ltd.
`1-406-1, Yoshino-cho, Omiya-shi, Saitama
`(72) Inventor: Masato TAKAHASHI
`c/o Tokyo Plant
`Shin-Etsu Polymer Co., Ltd.
`1-406-1, Yoshino-cho, Omiya-shi, Saitama
`(72) Inventor: Yoshiaki FUJIMORI
`c/o Tokyo Plant
`Shin-Etsu Polymer Co., Ltd.
`1-406-1, Yoshino-cho, Omiya-shi, Saitama
`(74) Representative: Ryoichi YAMAMOTO, Patent Attorney
`(and one other)
`
`
`
`Sony Corp. Exhibit 1008
`
`SONY_000673
`
`
`
`(11) Japanese Patent Laid-Open No. Hei 4-278922
`(43) Japanese Patent Laid-Open Date: October 5, 1992
`(21) Japanese Patent Application No. Hei 3-68068
`(22) Japanese Patent Application Date: March 7, 1991
`(71) Applicant: 000190116
`Shin-Etsu Polymer Co., Ltd.
`4-3-5, Nihonbashi-Honcho, Chuo-ku, Tokyo
`(72) Inventor: Tsutomu SUZUKI
`c/o Product Research Center
`Shin-Etsu Polymer Co., Ltd.
`1-406-1, Yoshino-cho, Omiya-shi, Saitama
`(72) Inventor: Masato TAKAHASHI
`c/o Tokyo Plant
`Shin-Etsu Polymer Co., Ltd.
`1-406-1, Yoshino-cho, Omiya-shi, Saitama
`(72) Inventor: Yoshiaki FUJIMORI
`c/o Tokyo Plant
`Shin-Etsu Polymer Co., Ltd.
`1-406-1, Yoshino-cho, Omiya-shi, Saitama
`(74) Representative: Ryoichi YAMAMOTO, Patent Attorney
`(and one other)
`
`
`
`Sony Corp. Exhibit 1008
`
`SONY_000673
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`2
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`[Title of the Invention]
` Surface Light Source Device
`
`[Abstract] (Modified)
`[Object]
` The present invention improves an edge light type
`surface light source for uniformly illuminating a
`relatively large area by receiving light from a linear
`light source so that the surface light source has a high
`brightness and small variations in brightness
`distribution to be used as a backlight of a transmissive
`liquid crystal display apparatus.
`[Constitution]
` A surface light source device according to the
`present invention includes a light diffusing plate 1, a
`transparent light guide plate 2, and a reflective plate 3
`sequentially laminated from a direction of a line of
`sight. At least one surface of the transparent light
`guide plate 2 is provided with recesses of conical dots 6
`in a form of an embossed pattern, and a linear light
`source 5 surrounded by a reflector 4 is provided at at
`least one end edge of the transparent light guide plate 2.
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`SONY_000674
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`[What is Claimed is]
`[Claim 1]
` A surface light source device comprising:
` a light diffusing plate;
` a transparent light guide plate; and
` a reflective plate, the light diffusing plate,
`transparent light guide plate and reflective plate being
`sequentially laminated from a direction of a line of
`sight,
` wherein at least one surface of the transparent
`light guide plate is provided with recesses of conical
`dots in a form of an embossed pattern, and
` a linear light source surrounded by a reflector is
`provided at at least one end edge of the transparent
`light guide plate.
`[Claim 2]
` The device according to claim 1,
` wherein an oblique surface area of each of the
`conical dots of the transparent light guide plate is
`gradually increased according to distance from the linear
`light source.
`[Claim 3]
` The device according to claim 1 or 2,
` wherein an oblique surface area A of each of the
`conical dots of the transparent light guide plate is
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`SONY_000675
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`increased according to distance L from the linear light
`source in accordance with an equation A = α × exp(β × L),
`where α and β are constants.
`[Detailed Description of the Invention]
`[0001]
`[Applicable Industrial Field]
` The present invention relates to an edge light type
`surface light source device for uniformly illuminating a
`relatively large area by receiving light from a linear
`light source, and particularly to a surface light source
`device that has a high brightness and small variations in
`brightness distribution and which is used as a backlight
`of a transmissive liquid crystal display apparatus.
`[0002]
`[Prior Art]
` Recently, as display apparatuses are desired to be
`reduced in thickness and weight, liquid crystal display
`apparatuses have spread dramatically in place of cathode-
`ray tubes in the past. An increasing number of such
`liquid crystal display apparatuses have recently been
`provided with a back surface illuminating device
`(hereinafter referred to as a backlight) from a viewpoint
`of improving the visibility of the liquid crystal display
`apparatuses. Employed as this backlight at present is an
`EL (electroluminescence) light emitting body, a plurality
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`SONY_000676
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`of fluorescent tubes arranged directly under a liquid
`crystal display panel, or the like. However, the EL light
`emitting body does not have a sufficiently long life. The
`fluorescent tubes require a housing box having a
`thickness equal to or more than the diameter of the
`fluorescent tubes and a diffusing plate or a dimming
`sheet for adjusting a brightness distribution. Thus, the
`fluorescent tubes are difficult to thin, and are not
`sufficiently satisfactory as a surface light source
`device considering the complex constitution of the
`fluorescent tubes.
`[0003]
` In order to remedy this, a proposition has already
`been made to use one transparent light guide plate
`(hereinafter referred to as a light guide plate),
`introduce light from a linear light source provided at
`one end edge of the light guide plate, and thereby obtain
`a surface illumination. However, although substantially
`uniform brightness is obtained over the entire surface of
`the light guide plate when incident light from the linear
`light source travels in parallel with both surfaces of
`the light guide plate, actual incident light spreads
`radially, and because of attenuation and the like within
`the light guide plate, there are a large amount of
`incident light in the vicinity of the linear light source
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`SONY_000677
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`and a small amount of incident light at positions distant
`from the light source. Thus, uniform surface illumination
`cannot be obtained.
`[0004]
` Methods already proposed as measures for obtaining
`uniform brightness in a direction of a line of sight when
`one such light guide plate is used are roughly classified
`into the following two kinds.
` (1) Methods of devising the shape of the light
`guide plate or patterns provided to a surface for
`reflection, scattering, refraction of incident light, as
`represented by a method of roughening the back surface of
`a light guide plate and cutting part of an end edge of
`the light guide plate on an opposite side from a linear
`light source into an oblique surface (Japanese Patent
`Publication No. Sho 58-17957), a method of roughening the
`back surface of a light guide plate into a hairline shape
`in parallel with the direction of incident light from a
`linear light source (Japanese Utility Model Publication
`No. Sho 58-25405), a method of forming one surface of a
`light guide plate into the shape of a particular curve
`(Japanese Patent Laid-Open No. Sho 63-208001), a method
`of forming a Fresnel-shaped surface on the back surface
`of a light guide plate whose section has a wedge shape
`and changing the inclination of surfaces of groove walls
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`SONY_000678
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`according to distance from a linear light source
`(Japanese Patent Laid-Open No. Sho 64-11203), and the
`like.
`[0005]
` (2) A method of combining a light guide plate with
`a material having a different index of refraction from
`the light guide plate. For example, there are methods of
`coating or printing the surface of a light guide plate
`with a light scattering material whose concentration
`(density) changes according to distance from a linear
`light source (Japanese Patent Laid-Open No. Sho 63-62104),
`(Japanese Patent Laid-Open No. Hei 1-107406), (Japanese
`Patent Laid-Open No. Hei 1-245220), and (Japanese Patent
`Laid-Open No. Hei 2-160215), or methods using (1) and (2)
`in combination with each other. Part of the methods have
`already been put to practical use.
`[0006]
`[Problems to be Solved by the Invention]
` However, the method (1) requires very fine and
`precise processing to be performed on the surface of the
`light guide plate. The method (1) therefore has
`difficulties in terms of production and in terms of cost,
`and is not satisfactory because the apparatuses are
`desired to be reduced in cost. In addition, the method
`(2) does not have much to offer considering that complex
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`SONY_000679
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`processing is involved, because of a light absorption
`loss due to the light scattering material, a paint, the
`management of a coating process, limitations of the
`printing method for the fine processing, and the like.
`The method (2) may not necessarily be said to be an
`excellent method in terms of mass productivity either.
`[0007]
`[Means for Solving the Problems]
` It is an object of the present invention to provide
`a surface light source device for solving the above
`problems of the related art and providing brightness and
`uniformity better than in the related art, by a simple
`constitution easy to manufacture and at low cost. This
`surface light source device includes a light diffusing
`plate, a transparent light guide plate, and a reflective
`plate sequentially laminated from a direction of a line
`of sight. At least one surface of the transparent light
`guide plate is provided with recesses of conical dots in
`a form of an embossed pattern, and a linear light source
`surrounded by a reflector is provided at at least one end
`edge of the transparent light guide plate.
`[0008]
`[Operation]
` The surface light source device according to the
`present invention is thus provided with the embossed
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`SONY_000680
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`pattern formed by distributing the recesses in the form
`of the conical dots in at least one surface of the light
`guide plate. Therefore, when light entering from one end
`edge of the light guide plate reaches the oblique surface
`or the vertex of each of the conical dots, the light is
`totally reflected or refracted at the oblique surface and
`repeats transmission according to an angle that the light
`makes with the oblique surface, that is, the magnitude of
`an angle of incidence, due to an air layer having a
`smaller index of refraction than the light guide plate
`which air layer is present between the light guide plate
`and the reflective plate or the light diffusing plate,
`and the light travels efficiently while scattering within
`the light guide plate. Thus a surface light source device
`having high brightness can be obtained by a relatively
`thin single light guide plate.
`[0009]
` As a result, as compared with the surface
`processing method using the light scattering material
`according to the related art, there is a small light
`absorption loss at the time of reflection, and a high
`efficiency is obtained. In addition, the shape of the
`oblique surfaces corresponding to the edges of cones
`reflects and refracts light in other than a direction of
`incidence. Thus, an effect of the brightness distribution
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`SONY_000681
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`in the axial direction of the linear light source on the
`brightness distribution of a light emitting surface is
`considered to be alleviated. Consequently, a surface
`light source having more uniform brightness is expected.
`In addition, when the conical dots are formed such that
`the oblique surface area of the conical dots is increased
`in proportion to the logarithm of distance from the light
`source, uniform brightness as viewed from the direction
`of the line of sight is obtained in spite of differences
`in angle of incidence at positions distant from the
`linear light source and the attenuation of incident light.
`[0010]
` Various modes for carrying out the present
`invention will hereinafter be described with reference to
`the drawings. As shown in FIG. 1(a), a surface light
`source device according to the present invention includes
`a light diffusing plate 1, a light guide plate 2, and a
`reflective plate 3, which are sequentially laminated in a
`direction of a line of sight (emitting direction), and a
`linear light source 5 surrounded by a reflector 4 and
`installed at one end edge of the light guide plate 2. The
`light diffusing plate 1 is desired to diffuse light
`incident from the light guide plate 2 uniformly over an
`entire surface, and is desired to be principally a white
`surface light source when used as a backlight of a liquid
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`SONY_000682
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`11
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`crystal display panel or the like. Thus, generally used
`as the light diffusing plate 1 is a milk-white sheet or
`plate formed by a transparent or translucent resin such
`as an acrylic resin, a polycarbonate resin, a
`polyethylene terephthalate resin, or the like containing
`a light diffusing agent such as a titanium oxide, for
`example, or what is obtained by coating one surface or
`both surfaces of these resins processed into the shape of
`a sheet with a paint containing a light diffusing agent.
`In this case, depending on the kind and amount of the
`contained light diffusing agent and the thickness of the
`sheet or the plate, a diffusion effect is decreased, and
`transmittance becomes low, consequently decreasing
`surface brightness. It is therefore desirable to select
`one suitable for desired characteristics of the device.
`[0011]
` It is to be noted that the present inventor et al.
`have found as a result of various studies that uniform
`brightness is obtained by forming conical dots 6 in an
`embossed pattern formed in the surface of the light guide
`plate such that the oblique surface area A of each of the
`conical dots 6 gradually increases in proportion to the
`logarithm of a distance L from the linear light source,
`that is, according to an equation expressed as A = α ×
`exp(β × L) (where α is the oblique surface area of a
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`SONY_000683
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`first dot closest to the linear light source, and β is a
`constant), as shown in FIG. 1(b). In actuality, settings
`and processing are performed so as to satisfy these
`conditions by only distances from the surface of the
`light guide plate to the vertexes of the dots, that is,
`the depths of the conical dots, while the oblique surface
`angle and the longitudinal and lateral pitches of the
`conical dots are set constant. α and β in the equation
`are subject to the materials, shapes, and the like of the
`constituent members being used. Thus, an optimum
`constitution may be selected. When α is too large, in
`particular, uniform brightness cannot be obtained even
`when the oblique surface areas of the conical dots have a
`distribution proportional to the logarithm of the
`distance L from the light source. Conversely, when α is
`too small, efficiency of use of incident light is low,
`and consequently a bright light emitting surface is not
`obtained. Therefore an optimum value needs to be obtained
`empirically.
`[0012]
` In addition, the distribution setting of the
`oblique surface areas of the conical dots is not
`necessarily limited to only perpendicular distances from
`the linear light source. A distribution can be provided
`in a direction parallel with the linear light source as
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`SONY_000684
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`required so as to correspond to the brightness
`distribution in the axial direction of the linear light
`source as already described, for example. FIGS. 1(c) and
`(d) show states in which light is reflected by the
`oblique surfaces of the conical dots within the light
`guide plate.
`[0013]
` The pitches, oblique surface angle, shape, and the
`like of the conical dots that are set in this case are
`not limited. For example, both of the longitudinal and
`lateral pitches do not necessarily need to be constant.
`In addition, the arrangement of embossed patterns
`adjacent to each other may be at the same pitch as shown
`in FIGS. 2(a) and (b), or may be in the form of a
`staggered lattice as shown in (c) and (d), or a
`combination of both may be used. However, when the pitch
`is too large, for example when the pitch is 5 mm or more
`for a liquid crystal display panel, the number of conical
`dots is reduced, which not only results in a decrease in
`efficiency of use of incident light and a consequent
`decrease in brightness but also results in the embossed
`patterns being seen through the light diffusing plate
`because of the large pitch, thus causing non-uniformity
`in external appearance. When the pitch is too small, fine
`processing is performed, which may lead to a high cost
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`SONY_000685
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`and a lack of practicality. Therefore, the pitch is
`preferably set appropriately according to an intended
`purpose such as an external appearance at a time of light
`emission, combination with a liquid crystal display panel
`installed on the upper surface, or the like.
`[0014]
` In addition, an angle θ that the oblique surfaces
`of the conical dots make with the surface of the light
`guide plate is not particularly limited either. However,
`for example, in a case where the incident light is
`parallel light rays traveling in straight lines
`perpendicularly to the direction of thickness of the
`light guide plate, and polymethacrylate (critical angle
`of 42°10’) is used as the light guide plate, when θ is
`set at 48° or less, the incident light that has reached
`the oblique surfaces of the cones is emitted to the
`outside of the system of the light guide plate by total
`reflection, and is emitted in the direction of the line
`of sight. Further, the shape of the dots is not limited
`to a conical shape, but may be other similar shapes. For
`example, the shape of the oblique surfaces may be
`outwardly convex rather than a straight line as shown in
`(e) and (f) of FIG. 2, or may be formed by a concave
`curved surface as shown in (g) and (h). The vertex of the
`cone of a dot may not be on a normal passing through the
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`SONY_000686
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`15
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`center of the circle of a base as shown in (i) and (j).
`Further, a truncated conical shape may be formed as shown
`in (k) and (l). Alternatively, combinations thereof may
`be used. Further, the dots may be symmetrically on both
`surfaces of the light guide plate as shown in FIG. 3(a),
`or may be placed asymmetrically on both surfaces of the
`light guide plate as shown in (b) or (c). In addition, as
`shown in FIGS. 4(a) and (b), the section of the light
`guide plate may be gradually thinned with increase in the
`distance from the linear light source, or may be
`undulated. These conditions related to the embossed
`patterns of the conical dots may be any combination as
`long as the oblique surface area of the conical dots is
`gradually increased in proportion to the logarithm of the
`distance from the light source and is set so as to
`achieve a uniform brightness of the light emitting
`surface.
`[0015]
` Incidentally, a base material for the light guide
`plate 2 may be any of glass, an epoxy resin, a silicon
`resin, and other thermosetting resins, an acrylic resin,
`a polycarbonate resin, polypropylene, polyethylene, and
`other polyolefin resins, other thermoplastic resins, and
`the like. However, an acrylic resin, a polycarbonate
`resin, a silicone rubber, polymer alloys thereof, and the
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`SONY_000687
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`like are desirable from a viewpoint of transmittance,
`processability, heat resistance, and the like.
`[0016]
` In addition, the embossed pattern may be provided
`to the light guide plate 2 by any method. For example,
`the embossed pattern can be easily obtained by directly
`performing machining, by transferring a pattern provided
`in advance on a separate member of a roll-shaped or
`plate-shaped steel material or the like by hot pressing
`in the case of a thermoplastic resin, or by injection
`molding or a casting method using a molding die such that
`a molded piece has the pattern.
`[0017]
` The reflective layer 3 has a function of reducing a
`loss of light by sending back light leaked out to the
`outside of the system due to refraction and the like by
`the light guide plate into the system by reflection,
`diffusion, and the like. A thick reflecting and diffusing
`layer having a high reflectance is desirable from a
`viewpoint of efficiency of use of light, such a layer
`being for example a sheet on which a metal such as
`aluminum, silver, or the like is deposited, a resin plate
`kneaded or coated with a diffusing material such as
`titanium oxide, silica, glass beads, or the like or a
`paint, a sheet, a metallic plate, or the like.
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`SONY_000688
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`[0018]
`[Example]
` A surface light source device having the following
`constitution was produced as an example. A result of an
`experiment on the surface light source device is shown in
`Table 1.
`(1) Light Diffusing Sheet
` D204 (name of a product manufactured by Kimoto Co.,
`Ltd.) 90 μm thick having polyethylene terephthalate as a
`base material
`(2) Light Guide Plate
` Conical dots that had a surface angle of 45° and
`whose oblique surface area increased logarithmically were
`arranged on one surface of a 230 × 130 × 3 mm acrylic
`cast plate Acrylite L (name of a product manufactured by
`Mitsubishi Rayon Co., Ltd.) so as to be distributed as
`shown in FIGS. 2(a) and (b) at a longitudinal and a
`lateral pitch of 1.2 mm.
`(3) Reflective Plate
` An aluminum plate having a thickness of 0.3 mm was
`coated with a paint obtained by mixing 35 weight percent
`of titanium powder in a polyester resin.
`(4) Light Source
` One three-wavelength cold-cathode tube (produced by
`Harison Electric Corporation) having a tube diameter of
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`5.8 mm, an effective light emission length of 130 mm, and
`a tube brightness of 7000 nit was installed at one end
`edge of a short side of the light guide plate, and was
`lit with a direct-current voltage of 12 V applied via an
`inverter. The reflector was the same member as the
`reflective plate, and was provided with directivity to
`reduce a loss of light emitted by the linear light source
`and efficiently guide the light to the incidence end edge
`of the light guide plate.
` Brightness Distribution (%) = (Lowest In-Plane
`Brightness – Highest In-Plane Brightness)/Highest In-
`Plane Brightness × 100
` The brightness distribution of a second comparative
`example is mainly a brightness distribution in the
`vicinity of electrodes of the cold-cathode tube.
` Brightness Distribution Curve: a brightness
`distribution curve with respect to the distance L from
`the linear light source along a line X-X in the center in
`the axial direction of the linear light source shown in
`FIG. 1
`[0019]
` Table 1
`[0020]
` Table 1 shows, for comparison, results of
`experiments on surface light source devices having light
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`SONY_000690
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`guide plates according to the related art that are
`different from the example in the following respects.
`First Comparative Example
` A first comparative example represents a case of a
`light guide plate in which the oblique surface area of
`the conical dots increased in linear proportion to the
`distance from the linear light source. In this case, the
`brightness distribution was markedly nonuniform. Thus,
`the surface light source device is not suitable as a
`surface light source.
`Second Comparative Example
` A second comparative example represents a case
`where hairline-shaped grooves that were parallel with the
`linear light source and whose sectional shape and size
`had a similar distribution to that of the conical dots
`according to the example were formed in one surface of a
`light guide plate. In this case, surface brightness was
`170 nit. A brightness distribution curve in a direction
`perpendicular to the light source was similar to the
`example, and was improved as compared with the first
`comparative example because the distribution of the
`hairlines was based on a logarithm. However, hairline
`processing performed in parallel with a direction of
`length of the linear light source provided less effect of
`reflection and refraction in other than a direction of
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`incidence, which effect was expected from the conical
`shape according to the example. As a result, a brightness
`distribution in the direction of length of the linear
`light source could not be fully accommodated. A
`brightness distribution of 14% mainly at both ends of the
`light source was inferior to 8% in the example.
`Third Comparative Example
` One surface of a light guide plate was coated with
`a polyester resin paint mixed with 40 weight percent of
`titanium oxide, and a conical dot pattern whose area
`increased in proportion to the logarithm of distance from
`the light source was formed by screen printing. The
`brightness of the surface of the light guide plate was
`somewhat decreased as compared with the example.
`[0021]
`[Effects of the Invention]
` As described above, light entering the light guide
`plate from the linear light source according to the
`present invention repeats transmission or total
`reflection according to an angle of incidence of the
`light at the oblique surface or side of each of the
`conical dots due to an air layer having a smaller index
`of refraction than the light guide plate which air layer
`is present between the light guide plate and the
`reflective plate, and travels while scattering
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`SONY_000692
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`efficiently within the light guide plate also in a
`direction parallel with the linear light source using the
`oblique surfaces of the conical dots. In addition, the
`reflection involves a small light absorption loss due to
`an ink as compared with a method of printing a paint onto
`the light guide plate. Thus, a light guide plate
`relatively thinner than the light guide plate according
`to the related art can provide a uniform surface
`brightness at an equal level or a higher level. Further,
`increasing the oblique surface areas of the conical dots
`in proportion to the logarithm of distance from the light
`source makes it possible to realize a light guide plate
`integral with a dimming pattern without using a separate
`member for dimming in particular. Therefore the surface
`light source device can be reduced in thickness and
`weight using a simple constitution.
`[Brief Description of the Drawings]
`[FIG. 1]
` (a) is a perspective view of a surface light source
`device according to the present invention, (b) is a
`sectional view taken along a line X-X of (a), and (c) and
`(d) are a schematic sectional view and a schematic plan
`view, respectively, of assistance in explaining the
`behavior of incident light within a light guide plate.
`[FIG. 2]
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`SONY_000693
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` (a) is a plan view in which conical dots of a light
`guide plate according to the present invention are
`arranged at same pitches longitudinally and laterally,
`(b) is a sectional view taken along a line X-X of (a),
`(c) is a plan view in which the conical dots of a light
`guide plate are arranged in the form of a staggered
`lattice, (d) is a sectional view taken along a line X-X
`of (c), (e) is a plan view in which the oblique surfaces
`of the conical dots of a light guide plate are outwardly
`convex, (f) is a sectional view taken along a line X-X of
`(e), (g) is a plan view in which the oblique surfaces of
`the conical dots are outwardly concave, (h) is a
`sectional view taken along a line X-X of (g), (i) is a
`plan view in which the vertexes of the conical dots are
`displaced from the centers of bases, (j) is a sectional
`view taken along a line X-X of (i), (k) is a plan view in
`which dots have a truncated conical shape, and (l) is a
`sectional view taken along a line X-X of (k).
`[FIG. 3]
` (a) is a sectional view in which the conical dots
`of a light guide plate according to the present invention
`are opposed to each other on both surfaces of the light
`guide plate, (b) is a sectional view in which the dots
`provided on both surfaces of a light guide plate are not
`opposed to each other, and (c) is a sectional view in
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`SONY_000694
`
`
`
`23
`
`which the dots provided on both surfaces of a light guide
`plate are gathered in respective groups and are not
`opposed to each other.
`[FIG. 4]
` (a) is a sectional view in which a light guide
`plate having conical dots in one surface according to the
`present invention has a wedge shape that is thinned with
`increase in distance from a linear light source, and (b)
`is a sectional view in which thickness is changed in an
`undulated manner.
`[Description of Reference Symbols]
`1 Light diffusing plate
`2 Light guide plate
`3 Reflective plate
`4 Reflector
`5 Fluorescent tube
`6 Conical dot
`
`SONY_000695
`
`
`
`24
`
`24
`
`In the drawings:
`
`In the drawings:
`
`[FIG. 1]
`
`
`
`
`
`SONY_000696
`
`SONY_000696
`
`
`
`2525
`
`
`
`25
`
`[FIG. 2]
`
`
`
`
`[FIG. 3]
`
`
`
`
`
`
`
`SONY_000697SONY_000697
`
`SONY_000697
`
`
`
`2626
`
`
`
`26
`
`[FIG. 4]
`
`
`
`
`
`
`
`
`
`SONY_000698SONY_000698
`
`SONY_000698
`
`
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