`
`(19) JAPANESE PATENT OFFICE (JP)
`
`(12) GAZETTE OF PATENT PUBLICATION (A)
`
`(11) PUBLICATION NUMBER OF PATENT APPLICATION
`
`PP H6-273756
`
`(43) DATE OF PUBLICATION SEPTEMBER 30, HEISEI 6 YEAR (1994.9.30)
`
`
`
`(51) Int. Cl. 5 Identification Symbol Reference Number FI Technology Expression Part
`
`G02F 1/1335
`
`F21S 1/00
`
`G02B 6/00
`
`
`
`
`
`
`
`530 7408-2K
`
` E 8815-3K
`
`331 6920-2K
`
`Request Of Examination Unrequested Number Of Claims 4 OL (Total 5 Pages)
`
`
`
`(21) APPLICATION NUMBER PA H5-62028
`
`(22) APPLICATION DATE
`
`MARCH 22, HEISEI 5 YEAR (1993.3.22)
`
`(71) APPLICANT
`
`000003757
`
`
`
`
`
`
`
`
`
`
`
`
`
`TOSHIBA LI-TEC, Co.
`
`TOKYODO SINAGAWAKU HIGASINAGAWA 4-3-1
`
`(72) INVENTOR
`
`TOKUNAGA GYOKO
`
`
`
`
`
`(74) AGENT
`
`
`
`
`
`
`
`
`
`TOKYODO MINATOKU MITA 1-4-28 TOSHIBA LI-TEC, Co.
`
`PATENT ATTORNEY HATANO HISASHI (ONE OTHER PERSON)
`
`1
`
`Mercedes-Benz Ex. 1008
`
`MBI_001386
`
`
`
`
`
`(54) [NAME OF INVENTION] ILLUMINATING DEVICE AND LIQUID CRYSTAL
`
`DISPLAY DEVICE
`
`(57) [ABSTRACT]
`
`[PURPOSE] Brightness and efficiency are increased by reducing or preventing leakage of light
`
`leaking from a light guide body to an exterior.
`
`[CONSTITUTION] A plurality of rough surface reflecting portions (17) where a light from a
`
`pair of fluorescent lamps (14a, 14b) is reflected on a rough surface and is guided toward a light
`
`emitting surface (13a) are formed on an opposite surface opposite to the light emitting surface
`
`(13a) of a light guide body (13). As the rough surface reflecting portions (17) become farther
`
`from the pair of fluorescent lamps (14a, 14b), a density of the rough surface reflecting portions
`
`increases.
`
`
`
`
`
`[SCOPE OF CLAIMS]
`
`[CLAIM 1] An illuminating device comprising a light source, and a light guide body receiving a
`
`light from the light source and guiding the light toward a light emitting surface, wherein a
`
`
`
`2
`
`MBI_001387
`
`
`
`
`
`plurality of rough surface reflecting portions where the light from the light source is reflected on
`
`a rough surface and is guided toward the light emitting surface are formed on an opposite surface
`
`opposite to the light emitting surface of the light guide body.
`
`[CLAIM 2] The illuminating device, wherein the rough surface reflecting portions are formed
`
`such that a density of the rough surface reflecting portions increases as the rough surface
`
`reflecting portions become farther from the light source.
`
`[CLAIM 3] An illuminating device, comprising: a light source; a light source reflecting part
`
`surrounding the light source and reflecting a light from the light source; a light guide body where
`
`a plurality of rough surface reflecting portions are formed denser as the rough surface reflecting
`
`portions become farther from the light source, the rough surface reflecting portions receiving the
`
`light from the light source, and a portion of the light from the light source reflected on a rough
`
`surface and guided toward a light emitting surface; a diffusing means on the light emitting
`
`surface of the light guide body; and a reflecting means on the rough surface reflecting portions.
`
`[CLAIM 4] A liquid crystal display device comprising the illuminating device of one of claims 1
`
`to 3, and a liquid crystal display panel whose rear surface is illuminated by the light from the
`
`illuminating device.
`
`[DETAILED DESCRIPTION OF INVENTION]
`
`[0001]
`
`[INDUSTRIAL UTILIZATION FIELD] The present invention relates to an illuminating device
`
`or a liquid crystal display device suitable for a backlight, etc. illuminating a rear surface of a
`
`
`
`3
`
`MBI_001388
`
`
`
`
`
`LCD (liquid crystal display device) panel, etc. Especially, the present invention relates to an
`
`illuminating device or a liquid crystal display device obtaining higher efficiency by reducing a
`
`loss of output light.
`
`[0002]
`
`[PRIOR ART] An example of this kind of an illuminating device according to the prior art, for
`
`example, is shown in FIG. 5. This illuminating device (1) is referred to as a side (edge) light
`
`type, where most of an inner surface (2a) of a lamp case (2) is formed as a reflecting surface.
`
`[0003] This lamp case (2) accommodates a light guide body (3) of a rectangular plate shape, for
`
`example, and one pair of left and right fluorescent lamps (4a, 4b) of a straight line shape, for
`
`example, which are disposed at sides of left and right end portions of the light guide body (3),
`
`therein. In addition, an LCD (liquid crystal display device) panel not shown is disposed and
`
`fixed on a light emitting surface (3a) which is a top surface of the drawing for the light guide
`
`body (3) through a diffusing sheet (5).
`
`[0004] Further, a reflecting film (6) of a dot shape composed of a white paint, for example, is
`
`formed on an outer bottom surface of the light guide body (3) by a printing, etc. The reflecting
`
`film (6) of a dot shape is formed such that a density of the dot becomes denser as the dot
`
`becomes farther from the fluorescent lamps (4a, 4b).
`
`[0005] Accordingly, although a portion of a light from one pair of fluorescent lamps (4a, 4b) is
`
`transmitted through an inside of the light guide body (3) and is totally reflected on a gap of the
`
`reflecting film (6) of a dot shape, a portion of the light is totally reflected on the reflecting film
`
`
`
`4
`
`MBI_001389
`
`
`
`
`
`(6) of a dot shape and the other light is diffused and reflected to be emitted from the light
`
`emitting surface (3a) toward the diffusing plate (5). The light is further diffused to illuminate a
`
`rear surface of the LCD panel not shown.
`
`[0006]
`
`[PROBLEM TO BE SOLVED BY THE INVENTION] However, in the illuminating device (1)
`
`according to the prior art as shown in FIG. 6, when the light designated by an arrow of the
`
`drawing in the light guide body (3) is reflected on the reflecting film (6) of a dot shape, a portion
`
`of the light leaks from an interface (K) between the rear surface of the light guide body (3) and
`
`the reflecting film (6) of a dot shape to an exterior to generate a loss of light. As a result, there
`
`is a problem such that efficiency as a unit is not necessarily high. In addition, since the
`
`reflecting film (6) of a dot shape is formed by a printing, absorption of light by printing ink is
`
`excessive.
`
`[0007] The present invention is performed based on this situation, and the object of the present
`
`invention is to provide an illuminating device and a liquid crystal display device which can
`
`improve the efficiency as a unit by reducing a loss of light.
`
`[0008]
`
`[MEANS FOR SOLVING PROBLEM] To solve the above problem, the present invention is
`
`composed as follows.
`
`[0009] The invention described in claim 1 of the present application (hereinafter, a first
`
`invention) is an illuminating device comprising a light source, and a light guide body receiving a
`
`
`
`5
`
`MBI_001390
`
`
`
`
`
`light from the light source and guiding the light toward a light emitting surface, wherein a
`
`plurality of rough surface reflecting portions where the light from the light source is reflected on
`
`a rough surface and is guided toward the light emitting surface are formed on an opposite surface
`
`opposite to the light emitting surface of the light guide body.
`
`[0010] In addition, the invention described in claim 2 of the present application (hereinafter, a
`
`second invention) is the illuminating device, wherein the rough surface reflecting portions are
`
`formed such that a density of the rough surface reflecting portions increases as the rough surface
`
`reflecting portions become farther from the light source.
`
`[0011] Further, the invention described in claim 3 of the present application (hereinafter, a third
`
`invention) is an illuminating device, comprising: a light source; a light source reflecting part
`
`surrounding the light source and reflecting a light from the light source; a light guide body where
`
`a plurality of rough surface reflecting portions are formed denser as the rough surface reflecting
`
`portions become farther from the light source, the rough surface reflecting portions receiving the
`
`light from the light source, and a portion of the light from the light source reflected on a rough
`
`surface and guided toward a light emitting surface; a diffusing means on the light emitting
`
`surface of the light guide body; and a reflecting means on the rough surface reflecting portions of
`
`the light guide body.
`
`[0012] Moreover, the invention described in claim 4 of the present application (hereinafter, a
`
`fourth invention) a liquid crystal display device comprising the illuminating device of one of
`
`claims 1 to 3, and a liquid crystal display panel whose rear surface is illuminated by the light
`
`
`
`6
`
`MBI_001391
`
`
`
`
`
`from the illuminating device.
`
`[0013]
`
`[OPERATION]
`
`A portion of a direct light from a light source or a reflected light from a light source reflecting
`
`part enters an inside of a light guide body. And a portion of the direct light or the reflected light
`
`is reflected on a plurality of rough surface reflecting portions and is guided toward a light
`
`emitting surface of the light guide body to illuminate an illuminated body such as a rear surface
`
`of a liquid crystal display panel, etc.
`
`[0014] Since each rough surface reflecting portion is formed directly on an opposite surface
`
`opposite to the light emitting surface of the light guide body, an interface is not formed between
`
`the opposite surface and the rough surface reflecting portion. As a result, it can be prevented
`
`that the light leak from the interface to an exterior, and a loss of light can be prevented and
`
`efficiency can be increased in accordance with prevention of the loss of light. In addition,
`
`although reflection on the reflecting portion is due to a total reflection, a loss is small because
`
`total reflectance of acryl is greater than reflectance of printing ink. As a result, surface
`
`brightness at a side of the light emitting surface of the light guide body can be increased.
`
`[0015] Further, in the second to fourth inventions, the density of the plurality of rough surface
`
`reflecting portions increases as the rough surface reflecting portions become farther from the
`
`light source. Accordingly, at a position near the light source of the light guide body, although
`
`relatively high brightness is obtained in the absence of the rough surface reflecting portions,
`
`
`
`7
`
`MBI_001392
`
`
`
`
`
`brightness is restrained because the density of the rough surface reflecting portions is relatively
`
`low. On the other hand, at a position far from the light source of the light guide body, although
`
`relatively low brightness is obtained in the absence of the rough surface reflecting portions, high
`
`brightness is obtained because the density of the rough surface reflecting portions is relatively
`
`high. As a result, uniformity in brightness is increased by planarizing brightness at a whole of
`
`the light emitting surface of the light guide body regardless of distance from the light source.
`
`[0016]
`
`[EMBODIMENTS] Embodiments of the present invention are illustrated with reference to
`
`accompanying drawings.
`
`[0017] FIG. 1 is a cross-sectional view showing an embodiment including the first to third
`
`inventions of the present application. In the drawing, an illuminating device (11) includes a
`
`light guide body (13) of a rectangular plate shape in a lamp case (12), and one pair of left and
`
`right fluorescent lamps (4a, 4b) which are disposed at sides of left and right end portions of the
`
`light guide body (13) therein.
`
`[0018] Most of an inner surface of the lamp case (12) is formed as a reflecting surface (12a) of a
`
`light source reflecting part. A relatively great opening (12b) is formed on a top surface of the
`
`lamp case (12) of the drawing. In addition, a lower reflecting sheet (15) is disposed on an inner
`
`bottom surface so that the light from a bottom surface of the light guide body (13) is reflected
`
`and sent back to the bottom surface.
`
`[0019] A top surface of the light guide body (13) of the drawing is a light emitting surface (13a)
`
`
`
`8
`
`MBI_001393
`
`
`
`
`
`of the light guide body (13) and a diffusing sheet (16) is disposed on the light emitting surface
`
`(13a). Left and right end portions of the diffusing sheet (16) are supported by end portions of
`
`the openings (12b) of the lamp case (12) along an up-and-down direction of the drawing and a
`
`plurality of rough surface reflecting portions (17) of a dot shape are nearly wholly formed on an
`
`outer bottom surface of the light guide body (13).
`
`[0020] Each rough surface reflecting portion (17) is formed on the outer bottom surface of the
`
`light guide body (13) by a process such as a sandblast or an etching. For example, as shown in
`
`FIG. 2, a rectangular groove which is convex along an upward direction of the drawing is formed
`
`and a rough surface is formed on a bottom surface of the groove at the same time. Further, the
`
`dot shape is disposed on a near whole of the outer bottom surface so that incident light shown as
`
`an arrow of the drawing is totally reflected as shown in FIG. 2.
`
`[0021] A dot density of the rough surface reflecting portions (17) of a dot shape becomes wider
`
`and denser as the rough surface reflecting portions (17) becomes farther from one pair of left and
`
`right fluorescent lamps (14a, 14b), i.e., nearer to a central portion. Accordingly, the rough
`
`surface reflecting portions (17) has a maximum in dot density at the central portion of the light
`
`guide body (13) along a left-and-right direction of the drawing and a minimum in dot density at
`
`the left and right end portions of the light guide body (13).
`
`[0022] The light from the one pair of left and right fluorescent lamps (14a, 14b) directly enters
`
`the light guide body (13) through the left and right end portions of the drawing and is transmitted
`
`toward the central portion. Alternatively, after the light from the one pair of left and right
`
`
`
`9
`
`MBI_001394
`
`
`
`
`
`fluorescent lamps (14a, 14b) is reflected on the reflecting surface (12a) of the lamp case (12), the
`
`light enters the light guide body (13) through the left and right end portions of the drawing and is
`
`transmitted toward the central portion. A portion of the light incident to the rough surface
`
`reflecting portions (17) of a dot shape is totally reflected as shown in FIG. 2, and the light
`
`reaching a gap between the rough surface reflecting portions (17) repeats a total reflection to be
`
`propagated in the light guide body (13).
`
`[0023] Accordingly, since each rough surface reflecting portion (17) formed directly on the outer
`
`bottom surface of the light guide body (13) and does not form an interface with the outer bottom
`
`surface, it is prevented that the light leaks from the interface to an exterior and efficiency can be
`
`increased in accordance with prevention of the light leakage. In addition, since total reflectance
`
`is greater than reflectance of printing ink, efficiency is further increased.
`
`[0024] In addition, at a position near the one pair of left and right fluorescent lamps (14a, 14b) of
`
`the light guide body (13), although brightness is relatively high in the absence of the rough
`
`surface reflecting portions, the density of the rough surface reflecting portions (17) of the
`
`position is low as compared with a central position. As a result, an amount of the light
`
`reflected on the rough surface reflecting portions (17) and emitted from the light emitting surface
`
`(13a) to the diffusing sheet (16) is reduced and brightness is restrained.
`
`[0025] On the other hand, at the central position far from the one pair of left and right fluorescent
`
`lamps (14a, 14b), although brightness is relatively low in the absence of the rough surface
`
`reflecting portions,, the density of the rough surface reflecting portions (17) has a maximum.
`
`
`
`10
`
`MBI_001395
`
`
`
`
`
`As a result, an amount of light reflected on the rough surface reflecting portions (17) and emitted
`
`from the light emitting surface (13a) to the diffusing sheet (16) increases and brightness is
`
`improved. Accordingly, brightness of the whole light emitting surface (13a) of the light guide
`
`body (13) can be planarized.
`
`[0026] FIG. 3 is a perspective view showing a cross-section of an embodiment of the fourth
`
`invention of the present application. In a liquid crystal display device (21) of the embodiment,
`
`a liquid crystal display panel (22) is disposed on the diffusing sheet (16) of the illuminating
`
`device (11) such that a rear surface of the liquid crystal display panel (22) closely adheres to the
`
`diffusing sheet (16) and the liquid crystal display panel (22) is supported by end portions of one
`
`pair of up-and-down openings (23a, 23b) of a lamp case (23). A driving circuit for the liquid
`
`crystal display panel (22) is not shown.
`
`[0027] In this liquid crystal display device (21), as mentioned above, since a rear surface of the
`
`liquid crystal display panel (22) is illuminated by the illuminating device (11) having low light
`
`loss, high efficiency, and high uniformity in brightness, brightness and uniformity in brightness
`
`of the liquid crystal display panel (22) can be improved.
`
`[0028] In addition, the liquid crystal display panel (22) may be substituted by an indicator board
`
`such as a guide plate having a required mark, etc. or a signboard to constitute an exit light or a
`
`signboard light.
`
`[0029] Further, although a case where the rough surface reflecting portions (17) are formed on
`
`the bottom of the rectangular groove of the light guide body (13) is illustrated in the above
`
`
`
`11
`
`MBI_001396
`
`
`
`
`
`embodiment, the present invention is not limited to this embodiment. For example, as a rough
`
`surface reflecting portion (31) shown in FIG. 4, rough surfaces (33c) may be formed on both
`
`slant surfaces (33a, 33b) of a triangular groove (33) on an outer bottom surface of a light guide
`
`body (32). The formation of the groove is not limited.
`
`[0030]
`
`[EFFECT OF INVENTION] As mentioned above, in the first to fourth inventions of the present
`
`application, since the plurality of rough surface reflecting portions are formed directly on the
`
`opposite surface opposite to the light emitting surface of the light guide body, an interface is not
`
`formed between the opposite surface of the light guide body and the rough surface reflecting
`
`portions. As a result, it can be prevented that the light leaks from the interface to an exterior,
`
`and efficiency as a unit can be increased in accordance with prevention of the light leakage. In
`
`addition, since the total reflectance is greater than reflectance of printing ink, efficiency can be
`
`further increased.
`
`[0031] Further, in the second to fourth inventions, since the density of the rough surface
`
`reflecting portions becomes denser as the rough surface reflecting portions becomes father from
`
`the light source, uniformity of the light emitting surface of the light guide body can increase.
`
`[BRIEF EXPLANATION OF DRAWINGS]
`
`[FIG. 1] A cross-sectional view of an illuminating device including first to third inventions of the
`
`present application.
`
`[FIG. 2] A magnified view of a main part showing a state where an incident light is totally
`
`
`
`12
`
`MBI_001397
`
`
`
`
`
`reflected at the rough surface reflecting portion of FIG. 1.
`
`[FIG. 3] A perspective view showing a cross-section of an embodiment of a liquid crystal display
`
`device according to the fourth invention of the present application.
`
`[FIG. 4] A magnified view of a main part showing a modified embodiment of the rough surface
`
`reflecting portion of FIG. 1.
`
`[FIG. 5] A cross-sectional view of an illuminating device of the prior art.
`
`[FIG. 6] A magnified view of a part of FIG. 5.
`
`[EXPLANATION OF REFERENCE NUMBERS]
`
`1
`
`12
`
`12a
`
`12b
`
`13
`
`13a
`
`
`
`
`
`
`
`
`
`
`
`
`
`illuminating device
`
`lamp case
`
`reflecting surface
`
`opening
`
`light guide body
`
`light emitting surface
`
`14a, 14b
`
`one pair of fluorescent lamps
`
`
`
`
`
`
`
`
`
`
`
`15
`
`16
`
`17
`
`21
`
`22
`
`
`
`lower reflecting sheet
`
`diffusing sheet
`
`rough surface reflecting portions
`
`liquid crystal display device
`
`liquid crystal display panel
`
`13
`
`MBI_001398
`
`
`
`
`
`23
`
`
`
`lamp case
`
`23a, 23b
`
`end portions of opening
`
`
`
`
`
`14
`
`MBI_001399
`
`
`
`
`
`[FIG. 1]
`[FIG. 1]
`
`
`
`
`
`[FIG. 2]
`
`I?
`
`13
`
`
`
`15
`15
`
`
`
`
`
`MBI_001400
`
`MBI_001400
`
`
`
`
`
`[FIG. 3]
`[FIG. 3]
`
`
`
`
`
`[FIG. 4]
`[FIG. 4]
`
`31
`
`
`
`
`
`MBI 001401
`
`33c
`
`32
`
`
`
`
`
`16
`16
`
`MBI_001401
`
`
`
`
`
`[FIG. 5]
`[FIG. 5]
`
`'.
`
`
`
`
`n
`..._'.—.EE."Lfi.-.W.'flEEfli‘EZfiEEflLfllfl’flfifl‘Efi'gL,
`.
`
`
`
`
`[FIG. 6]
`[FIG. 6]
`
`
`
`
`
`
`
`MBI_001402
`
`17
`17
`
`MBI_001402
`
`
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