WO2003069221A1

WO2003069221A1 - Lighting device, and liquid crystal display device using this lighting device

Info

Publication number: WO2003069221A1
Application number: PCT/JP2003/001430
Authority: WO
Inventors: Yasuhiro Kato; Takafumi Kashiwagi
Original assignee: Matsushita Electric Industrial Co., Ltd.
Priority date: 2002-02-12
Filing date: 2003-02-12
Publication date: 2003-08-21
Also published as: JP2005222698A; AU2003211932A1

Abstract

A lighting device; and a liquid crystal display device. A lighting device (UT1) comprising an optical waveguide (2) in the form of a substantially square having a lateral surface (2a), which forms an light entrance surface, between a pair of corners (X, X), and a bar-like light source (1) having opposite ends and a section between the opposite ends composed of non-luminous sections (1a, 1a) and a luminous section (1b), respectively, and disposed to extend along the light entrance surface of the optical waveguide, it being arranged that the light emitted from the light source to fall on the light entrance surface of the optical waveguide emerges from the upper surface (2b) of the optical waveguide, wherein the optical waveguide has notches (A1, A1) formed by notching the portions corresponding to the non-luminous sections of the light source at the corners (X, X)as seen in a plan view.

Description

Specification

Illumination device and liquid crystal display device using the illumination device

〔Technical field〕

The present invention relates to an illuminating device and a liquid crystal display device using the illuminating device, and more particularly to an illuminating device in which a rod-shaped light source having non-light emitting regions at both ends is disposed on a side surface of a light guide plate.

[Technical background]

2. Description of the Related Art Conventionally, a display device for an information device such as a laptop-type notebook-type word processor or a personal computer has been used to display images on a liquid crystal display panel by utilizing features such as light weight, thinness, and low power consumption. Tang is heavily used. Recently, the majority of LCD panels have built-in lighting units that illuminate the front area of the LCD panel from the back. With the spread of notebook PCs ゃ monitors and mopile PCs, this lighting unit is mainly of the edge-light type, in which the light source is arranged on one of the outer peripheral surfaces (end surfaces) of the light guide plate.

FIG. 14 is a perspective view of a main part of a conventional edge-light type illumination device UT, and FIG. 15 is a sectional view thereof. FIG. 16 is a cross-sectional view showing a configuration of a liquid crystal display device LCD using the lighting device UT.

In FIGS. 14 to 16, in this edge-lit type illumination device UT, for example, a fluorescent tube 1 such as a hot-cathode tube or a cold-cathode tube and a fluorescent tube 1 arranged in close proximity to the fluorescent tube 1 are provided. A light guide plate 2 that guides light; a reflection sheet 4 that is arranged along the surface of the light guide plate 2 and scatters and reflects light from the fluorescent tube 1 toward the liquid crystal display panel P; The light guide plate 2 includes a light reflector 5 for reflecting light from the fluorescent tube 1 toward the light guide plate 2, and a light collecting sheet 3 such as a diffusion sheet / prism sheet disposed on the upper surface of the light guide plate 2. 1, 2, 3, 4, and 5 are held by a resin or metal outer frame 6> 101.

The fluorescent tube 1, which is the light source, is a circular (rod-shaped) cold cathode fluorescent tube or hot cathode. A fluorescent tube is used. In each of the fluorescent tubes 1, electrodes (not shown in FIGS. 14 to 16; shown by a reference numeral 102 in FIG. 3 and the like) are provided at both ends of the cylindrical fluorescent tube 1. A lead wire (not shown) for supplying a predetermined driving voltage to the fluorescent tube 1 is connected to this electrode by soldering or the like, and a voltage necessary for lighting the fluorescent tube 1 is applied. You. In the fluorescent tube 1, a region 1b that emits light as a light source (hereinafter referred to as an effective light-emitting region (light-emitting portion) lb) is a central portion (force) between the portions 1a and 1a where the electrodes at both ends are formed. The electrodes at both ends do not emit light. Hereinafter, both ends 1 a and 1 a of the fluorescent tube 1 where the pair of electrodes are provided are referred to as non-light emitting portions. As a result, the effective light emitting region 1 b is shorter than the entire length of the fluorescent tube 1.

The light emitting plate 2 is formed by molding transparent resin into a rectangular shape, and has four side surfaces forming an outer peripheral surface, and upper and lower surfaces forming a pair of main surfaces.蛍光 A fluorescent tube 1 is arranged close to one side surface 2 a of the light plate 2 (hereinafter referred to as a light incident surface), and the light of the fluorescent tube 1 incident from the light incident surface 2 a is transmitted into the light guide plate 2. And exits from the upper surface 2b. In some cases, a fine light scattering pattern is formed on the lower surface opposite to the upper surface 2b. In FIG. 14, the fluorescent light 1 is arranged along one side surface 2a of the outer peripheral surface of the light guide plate 2, but is arranged along two opposite side surfaces of the light guide plate 2. Or an L-shaped fluorescent tube 1 in which a cylindrical fluorescent tube is bent along two adjacent sides of the light guide plate 2 (referred to as an “L-shaped fluorescent discharge tube”) In each case, electrodes are provided at both ends of the cylindrical fluorescent element 1.

The above-mentioned lighting device UT is provided with a liquid crystal display panel F on an irradiation surface side (upper side in the drawing) of the lighting device UT, and a metal frame (front side frame) 7 is attached to form a liquid crystal display device SLCD (No. 16). See figure).

In the liquid crystal display device LCD configured as described above, light emitted from the fluorescent tube 1 is condensed by the reflector 5 and enters the light incident surface 2 a of the light guide plate 2. The light is emitted from the upper surface 2 b of the light guide plate 2 while being scattered and reflected by the reflection sheet 4 as appropriate while traveling in the light guide plate 2. The emitted light is corrected by the light correction sheet 3 and illuminates the entire back surface of the liquid crystal display panel P, so that the characters and images projected on the display surface of the liquid crystal display panel P become visible.

However, in the conventional lighting device UT, as shown in FIG. 17, non-light-emitting portions 1a and 1a on which the electrodes of the fluorescent tube 1 are formed are provided at both ends of the light entrance surface 2a of the light guide plate 2. Are arranged. For this reason, the amount of light incident from both ends of the light entrance surface 2a (the portions facing the non-light emitting portions la and la) is small, and the light guide plate 2 is provided with the non-light emitting portions 1a and 1a of the fluorescent tube 1. The two opposing corners X 1, X 2 (that is, the two corners formed by the light incident surface 2 a and the other adjacent side surface) are darkened, and the light is emitted from the upper surface 2 b of the light guide plate 2. The brightness of the corners X and X was low. Due to the lower brightness of the corners X, X, there has been a problem that the uniformity of the brightness is maintained on the entire upper surface 2b of the light guide plate 2. The boundaries between the dark portions (hereinafter referred to as dark portions) of the corners X and X and other bright portions (hereinafter referred to as light portions) do not appear clearly, but as a whole, both ends of the effective light emitting area 1 b It can be seen that it is oblique so that it extends outward from (Fig. 17 schematically shows the dark area). Such a problem occurs in the diagonal corner of the upper surface 2 b of the light guide plate 2 in the L-shaped fluorescent tube 1, and two fluorescent tubes 1 are arranged along two opposing side surfaces of the light guide plate 2. In this case, it occurred at all corners of the upper surface 2b of the light plate 2.

In order to solve such a problem, when the effective light emitting area 1b of the fluorescent tube 1 is expanded so as to extend to both ends of the light incident surface 2a of the light guide plate 2, the non-light emitting portions la and 1a of the fluorescent tube 1 are increased. Is projected to the side of the light guide plate 2 (the overall length of the light source 1 is increased), and the overall size of the illuminating device UT is increased, contradicting the so-called narrow frame required for the liquid crystal display device CD. Become.

[Disclosure of the Invention]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems. Even if a non-light-emitting portion of a rod-shaped light source is arranged at the end of the light-entering surface, the corners of the light guide plate close to the non-light-emitting portion are not darkened, and uniform brightness is achieved over the entire upper surface of the light guide plate. An object of the present invention is to provide an illuminating device capable of achieving a high brightness and a liquid crystal display device having a uniform luminance while achieving a narrower frame by using the illuminating device.

In order to achieve these objects, a lighting device according to the present invention includes a light guide plate having a substantially quadrangular shape in a plan view and a side surface between a pair of corners constituting a light incident surface; A rod-shaped light source which is constituted by a non-light-emitting portion and a light-emitting portion between the ends, and which is disposed along the light-entering surface of the light guide plate; and wherein the light is emitted from the light source and enters the front IB light guide plate. In the illumination device configured so that light incident on the surface is emitted from the upper surface of the light guide plate, a portion of the light plate corresponding to the non-light-emitting portion of the light filter at the corner is cut out in a plan view. It has a notch. With this configuration, light incident on the notch surface of the notch from the light source is scattered and reflected there, so that the brightness at the corner of the light guide plate where the notch is formed is improved, thereby eliminating the dark portion. . The front IS notch may be substantially rectangular or square in plan view. With this configuration, the notch can be easily formed.

Further, the notch may have a shape having a step-shaped notch in plan view. With such a configuration, a notched surface can be formed along a light-dark boundary assumed when a notched portion is not provided.

Further, the stepped cutout surface may be formed along a straight line extending obliquely from the end of the light emitting portion of the light source so as to pass through the corner portion in plan view. With such a configuration, the brightness can be increased in a range where there is little excess or deficiency by making the straight line coincide with a light-dark boundary assumed when a notch is not provided.

The notch is formed such that a vertical surface perpendicular to the light incident surface and an inclined surface forming an angle of 45 degrees or less with respect to the vertical surface are adjacent to each other and are repeatedly formed in a plan view. The shape may have a surface. With such a configuration Then, in addition to improving the luminance due to the scattering at the notch surface, the path of the light incident on the notch from the light source can be made closer to the non-light-emitting portion of the light source. It can be improved more effectively.

In addition, of the corners formed by the vertical surface and the inclined surface of the cutout surface, corners protruding inward of the light guide plate are, when viewed in a plan view, from the end of the light emitting portion of the light source. It may be formed along a straight line extending obliquely through the corner. With this configuration, the brightness can be increased in a range where there is little excess or deficiency by making the straight line coincide with a light-dark boundary assumed when no cutout portion is provided.

Further, a light scattering structure that scatters light incident on the notch surface from inside the light guide plate may be formed on the notch surface of the notch portion. ^; In this configuration, the light incident on the notch surface from inside the light guide plate as well as the light source is also scattered by the scattering structure, effectively improving the brightness of the corners of the light guide plate where the notch is provided. can do.

Further, a liquid crystal display device according to the present invention includes the lighting device according to claims 1 to 7, wherein a liquid crystal is sandwiched between a pair of substrates on an irradiation surface side of the lighting device. _With such a configuration in which the display panel is provided, it is possible to prevent the unevenness of the brightness of the liquid crystal display panel by the cutout portion of the violent light plate, while reducing the size of the liquid crystal display device.

The above and other objects, features, and advantages of the present invention will be apparent from the following detailed description of preferred embodiments with reference to the accompanying drawings.

[Brief description of drawings]

FIG. 1 is a perspective view showing a main configuration of a lighting device according to a first embodiment of the present invention.

FIG. 2 is a plan view showing a configuration of a main part of the lighting device according to the first embodiment of the present invention.

FIG. 3 is an enlarged plan view of the cutout portion in FIG. FIG. 4 is a perspective view showing a main part configuration of a lighting device according to a second embodiment of the present invention.

FIG. 5 is a plan view showing a main configuration of a lighting device according to a second embodiment of the present invention.

FIG. 6 is an enlarged plan view of the notch in FIG.

FIG. 7 is a perspective view showing a main part configuration of a lighting device according to a third embodiment of the present invention.

FIG. 8 is a plan view showing a main configuration of a lighting device according to a third embodiment of the present invention.

FIG. 9 is an enlarged plan view of the notch in FIG.

FIGS. 10 (a) and 10 (b) are views showing a modified example of the cutout portion in the embodiment of the present invention. FIG. 10 (a) has a linear cutout surface. FIG. 10 (b) is a plan view showing a notch having a curved notch.

FIG. 11 is a partially enlarged view showing a configuration of a light guide plate of a lighting device according to a second embodiment of the present invention.

FIG. 12 is a plan view showing a main configuration of a lighting device having an L-shaped fluorescent light as an application example of the embodiment of the present invention.

FIG. 13 is a sectional view showing a configuration of a liquid crystal display device according to an embodiment of the present invention.

FIG. 14 is a perspective view showing a configuration of a main part of a conventional edge light type lighting device.

FIG. 15 is a cross-sectional view showing a configuration of a main part of a conventional edge light type lighting device.

FIG. 16 is a cross-sectional view showing a configuration of a liquid crystal display device using a conventional lighting device.

FIG. 17 is a plan view schematically showing a dark portion generated in a conventional lighting device. [Best mode for carrying out the invention]

Hereinafter, embodiments of the present invention will be described with reference to the drawings. (First Embodiment)

The illumination device UT1 according to the first embodiment of the present invention illuminates a transmissive liquid crystal display panel from its surface as shown in FIG. 1, FIG. 4, and FIG. It is also called a backlight device. FIG. 13 is a cross-sectional view of a liquid crystal display device LCD1 including the lighting device UT1 of the present embodiment. With reference to FIGS. 1 and 13, this illuminating device UT 1 includes a light source 1, a light guide plate 2 that is arranged close to the light source 1 and guides light from the light source 1, and a light emitting plate 2. A reflection sheet 4 arranged along the back surface of the light source 1 to diffuse the light from the light source 1 toward the light plate 2, and a reflector 5 containing the light source 1 and reflecting the light from the light filter 1 toward the light guide plate 2 ( In particular, see FIG. 13), and a light correction sheet 3 composed of a diffusion sheet, a prism sheet, and the like, which is disposed on the light guide plate 2 and captures light emitted from the light guide plate (see especially FIG. 13). And outer frames 101 and 6 (see especially FIG. 13) for holding these members 1, 2, 3, 4 and 5. This outer frame is connected to the other housing (see FIG. 1) on the side opposite to the end on which the light-entering surface 2a of the light guide plate 2 is formed. (Not shown), and at least a portion of the side surfaces of the pair of housings and the lower surfaces of the reflector 5 and the reflection sheet 4 have a back surface force par 6. The housing 101 and the rear cover 16 are made of a resin or metal member.

Since the light source 1 is the same as that in the conventional example, a detailed description thereof is omitted, but the light source 1 is constituted by a cylindrical (bar-shaped) fluorescent tube, and electrodes 102 and 102 are provided at both ends (see FIG. 3). Here, in the present specification, the term “rod” refers to a shape extending along a virtual line (including not only a straight line but also a curved line), and not only a linear shape but also a curved shape (an L-shape described later). The portions of the fluorescent tube 1 where the electrodes 102 and 102 are formed are the non-light-emitting portions 1a and 1a. Area (light emitting unit) S

Reference numeral 1b denotes a central portion which is cut into the non-light-emitting portions 1a, 1a at both ends. As a result, the effective light emitting area 1 b is shorter than the entire length of the fluorescent tube 1. The light source 1 may be a cathode fluorescent tube or a hot cathode fluorescent tube.

The light guide plate 2 is formed by molding a polymethyl methacrylate (PMMA) resin into a substantially quadrangular plate shape. The light guide plate 2 has a substantially quadrangular shape that forms a pair of main surfaces and four side surfaces that mainly constitute the outer peripheral surface. And an upper surface and a lower surface. One of the four side surfaces (light incident surface) 2a is provided with a fluorescent tube 1 arranged closely adjacent thereto, and light from the light tube 1 is incident on the light incident surface 2a. The ends of the non-light-emitting portions 1a and 1a are positioned at both ends of the light-entering surface 2a of the light guide plate 2 so that the non-light-emitting portions 1a and 1a do not protrude laterally from the fluorescent plate 2. It is arranged to do. The light plate 2 is formed of two corners X, X (that is, the light incident surface 2a and the adjacent side surfaces 2c, 2c) adjacent to the non-light emitting portions la, la of the fluorescent tube 1. Notch A which is formed by cutting out a predetermined area of two corners.

In the lighting device UT 1 configured as described above, light emitted from the fluorescent tube 1 is condensed by the reflector 5, enters the light incident surface 2 a of the light guide plate 2, and travels inside the light guide plate 2. The light is emitted from the upper surface 2 b of the light guide plate 2 as appropriately scattered and reflected by the reflection sheet 4. At this time, the light emitted from the fluorescent tube 1 enters the notch surfaces A 1 a and A 1 b from the notch A 1 of the light guide plate 1 and is scattered and reflected there, so that the brightness at the corner X is improved. I do.

Next, the cutout portion, which is a special configuration of the present invention, will be described in detail. This notch can be formed in various shapes. Hereinafter, preferred embodiments of the shape of the notch in the present invention will be described.

[First embodiment]

FIG. 1 is a perspective view showing a main part configuration of a lighting device UT 1 according to a first embodiment of the present invention, FIG. 2 is a plan view thereof, and FIG. 3 is a cutaway view of FIG. FIG. 3 is an enlarged plan view of a part A1.

With reference to FIGS. 1 to 3, the notch A 1 of the light guide plate 2 A square or rectangle having a cutout surface composed of a surface A la perpendicular to the light incident surface 2a and a surface A 1b parallel to the light incident surface 2a (hereinafter referred to as a right-angled quadrilateral for convenience). Call) is formed. Reference numeral 103 denotes the boundary between the dark part and the light part in the conventional example, that is, the boundary between the dark part and the light part assumed assuming that the notch A1 does not exist (hereinafter referred to as a virtual light-dark boundary). Is shown. The notch A1 is formed so as to be located outside the virtual light-dark boundary 103.

In the illumination device UT1 configured as described above, the light L1 from the fluorescent tube 1 reaches the cutout A1 of the right-angled quadrangle obliquely, but this light L1 is cut out of the cutout A1. Since the light is scattered by A la and A 1 b, the brightness increases at the corners X and X. In other words, while there is no mechanism for scattering the light incident from the light source 1 and the reflector 5 at the corners X and X in the conventional example, the present example (the same applies to the following examples and embodiments). There are notches A 1 a and A 1 b of the notch A 1 at the corners X and X, and light incident from the light source 1 and the reflector 5 is scattered there. The brightness of X and X as a whole increases, and the dark part disappears. Therefore, the problem that only the corners X and X adjacent to the non-light-emitting portion 1a of the fluorescent tube 1 become large is solved, and the brightness of the entire upper surface 2b of the light guide plate 2 can be equalized. . In addition, the notches A 1, A 1 can be easily formed by simply notching a predetermined area of the corners X, X of the light guide plate 2 into a rectangular quadrangle.

[Second embodiment]

FIG. 4 is a perspective view showing a partial configuration of a lighting apparatus UT1 according to a second embodiment of the present invention, FIG. 5 is a plan view thereof, and FIG. 6 is a cutaway view of FIG. FIG. 4 is an enlarged plan view of a part A2.

4 to 6, notch A2 of light guide plate 2 has a surface A2a perpendicular to light entrance surface 2a and a surface parallel to light entrance surface 2a in plan view. A 2 b has a step-shaped notch formed so as to be repeated adjacent to each other. This notch is formed along the virtual light-dark boundary 103. PC leakage 30

10 As apparent from FIG. 17, the boundary between the dark part and the light part in the conventional example appears to pass obliquely through the corner X, so the virtual light-dark boundary 103 is the light incident surface 2 a It is supposed that the light passes through the corner X diagonally outward from the portion corresponding to the start end of the non-light emitting portion of the fluorescent tube 1. On the other hand, in the lighting device UT1 of the present embodiment, since the cutout surface of the cutout portion A2 is formed in a step shape, the cutout surface can be provided along the virtual light boundary 103. For this reason, the luminance can be increased in a range where there is little excess or deficiency.

[Third embodiment]

FIG. 7 is a perspective view showing a main part configuration of a lighting device UT1 according to a third embodiment of the present invention, FIG. 8 is a plan view thereof, and FIG. 9 is a cutaway portion of FIG. FIG. 4 is an enlarged plan view of A3.

With reference to FIGS. 7 to 9, the notch A 3 has a vertical surface A 3 a perpendicular to the light incident surface 2 a and an angle 0 of 45 degrees or less with respect to the vertical surface A 3 a. The inclined surface A3 has a notched surface formed so as to be repeated adjacent to each other. In this notch A3, the corner formed by the vertical plane A3a and the inclined plane A3b is formed at an acute angle in plan view, but is located at the back of the corner (light guide plate). 2 projecting inward) are formed along the virtual light-dark boundary 103. The notch becomes larger as approaching the other side 2c (the right side in FIG. 9) adjacent to the light incident surface 2a. Of the cutout surfaces of the cutout portion A3, the surface A3c closest to the other side surface 2c is formed parallel to the light incident surface 2a because the effect obtained by changing the light path is small. However, as shown by the dotted line, it may be formed so as to form an angle α of 45 degrees or less with respect to a plane A 3 a perpendicular to the light incident surface 2 a.

In the lighting device UT1 of the present embodiment thus configured, a plurality of (six in the present embodiment) surfaces A3a, A3b—A3 forming the concave and convex cutouts of the notch A3. Since the light is scattered by a and A 3 c, the brightness increases at the corners X and X, and it is possible to effectively uniform the brightness on the entire upper surface of the light emitting plate. In addition, in the conventional luminous plate 2, the fluorescent tubes 1 Although these lights proceeded obliquely straight (indicated by reference numeral L2 in FIG. 9), in this embodiment, the light is refracted by the notch portion A3, and the path (indicated by reference numeral L3 in FIG. 9). Therefore, according to the present embodiment, not only the light is scattered by the cutout portion A3, but also the light path is changed to the non-light-emitting portions la and 1a. Since the light guide plate 2 can be closer to the side, the brightness of the entire upper surface 2b of the light guide plate 2 can be made uniform, and the present invention can be used as the refractive index of the material of the light guide plate 2 increases. The effect of bringing the light path closer to the non-light-emitting portions la and 1a is greater, specifically, when the refractive index is not less than 1.3 and not more than 1.7, the light is more effectively transmitted to the non-light-emitting portions 1a and 1a. 1 Polycarbonate (PC) or polyethylene fiber, which can be guided to the Since the refractive index of the refraction rate (PET) is not less than 1,3 and not more than 1,7, the present invention exerts a great effect on many light guide plates 2.

In the lighting device of the present embodiment, the notch A is not limited to the shape of the above-described first to third examples, and the notch A is formed in accordance with the dark area of the corner X of the light guide plate 2 and the darkness. It is also possible to set the area and shape where the part A is provided. For example, the size of the notch A1 in the first embodiment is increased, or the surface A2a, A2b constituting the notch A2 in the second embodiment or the third embodiment is The number of surfaces A3a and A3b constituting the cutout portion A3 can be reduced as appropriate depending on the embodiment. '

Further, according to the embodiment, as shown in FIG. 10 (a), a notch portion having a notch surface A ′ a in a diagonal linear shape substantially along the virtual light boundary 103 in plan view. A 'or a notch A "having a curved notch A" a substantially along the virtual light-dark boundary 103 in plan view as shown in Fig. 10 (b). You may. In the configurations shown in FIGS. 10 (a) and 10 (b), the light L1 from the light emitting portion 1b of the light source 1 is scattered and reflected by the cutout surfaces A'a, A "a. As in the embodiment, the brightness at the corners of the light guide plate 2 can be improved, thereby eliminating the dark portions. „

PCT / JP03 / 01430

12

(Second embodiment)

FIG. 11 is a partially enlarged view showing a configuration of a light guide plate of a lighting device 2 according to a second embodiment of the present invention.

In FIG. 11, in the lighting device UT 2 of the present embodiment, the cutout portion 4 of the luminous plate 2 is substantially the same as the cutout portion A 1 of the first example of the first embodiment. However, a light scattering structure B that scatters emitted light is provided on each of the surfaces A4a and A4b that form the cutout surface of the cutout A4. The light scattering structure B may be formed by directly forming minute unevenness on each surface A4a A4b of the notch A4, or a light diffusion sheet having minute unevenness formed on the notch 4A. Alternatively, it may be configured by attaching to each surface Α · 4a, A4b. For example, by attaching fine acryl particles to a base film such as polyethylene terephthalate (PET) or polypropylene (PP), or by embossing the surface of the base film to form fine irregularities, this pace film is formed. Attaching to each side A 4a A 4b of the notch 4A allows the crotch to be made. As a result, not only the light arriving obliquely from the fluorescent tube 1 is scattered by the entire notch A4, but also the light arriving from various directions can be scattered by the light scattering structure B. The uniformity of the luminance over the entire upper surface can be more effectively achieved. In the second and third examples of the first embodiment, by providing the light scattering structure B on each surface of the cutout portion, it is possible to achieve more uniform luminance. .

(Application example)

The present invention is not limited to the rod shape of the fluorescent tube 1, and is applicable to a case where a fluorescent tube of another shape is provided. FIG. 12 is a plan view showing a configuration of a main part of a lighting device UT3 including an L-shaped fluorescent tube 1 as an application example of the above embodiment. The fluorescent tube 1 is an L-shaped fluorescent tube 1 obtained by bending a cylindrical fluorescent tube into an L shape, and has non-light emitting portions la and 1a at both ends. The L-shaped fluorescent tube 1 extends along two adjacent side surfaces 2a2a "of the outer peripheral surface of the light-emitting plate 2. The non-light-emitting portions 1 a, 1 a of the fluorescent tube 1 are close to (opposed to) the two corners X 2, X 2 on the diagonal line of the light guide plate 2. A cutout portion A (a cutout portion A1 in the first example of the first embodiment in FIG. 12) is provided in a predetermined area of X2 and X2. This makes it possible to compensate for the brightness of the two corners X 2, X 2 at which the non-light emitting portions la, 1 a of the light guide plate 2 face each other, thereby making the brightness of the entire upper surface 2 b uniform. As another example, when the fluorescent tubes 1 are respectively arranged along two opposing side surfaces of the outer peripheral surface of the light guide plate 2, the fluorescent tubes are provided at the four corners of the light guide plate 2. Since one non-light emitting portion 1a is arranged close to the other, a cutout portion A is provided in a predetermined region of the four ^ portions. Thereby, it is possible to eliminate the dark portion at the four corners of篛光plate 2 ₆

In the above-described embodiments and application examples of the present invention, the light guide plate is provided with a notch or the like at a pair of corners corresponding to the pair of non-light emitting portions of the light source. Needless to say, a configuration in which a notch or the like is provided in any one of them is also possible.

(Application to liquid crystal display)

Next, the liquid crystal display device LCD1 according to the embodiment of the present invention will be described.

FIG. 13 is a cross-sectional view illustrating a configuration of a liquid crystal display device LCD 1 according to the present embodiment. In FIG. 13, the same reference numerals as those in FIG. 1 denote the same or corresponding parts.

As shown in FIG. 13, the liquid crystal display device LCD 1 according to the present embodiment is equipped with the lighting device UT 1 of the first embodiment of the first embodiment. A liquid crystal display panel 配 is disposed on the irradiation surface side (upper side) of the illumination device UT 1, and a metal frame 7 is attached to the liquid crystal display device LCD 1. The liquid crystal display panel P is for displaying characters and images, and a pair of transparent substrates having display electrodes disposed on the inner surface thereof are opposed to each other so as to have an appropriate gap. And inject the liquid crystal material into the gap. It is manufactured by sealing the liquid crystal material with a sealant. Around the liquid crystal display panel P, a plurality of driving circuits for displaying an image or the like on the liquid crystal display panel P, and a board on which the driving circuit is mounted are arranged. Conventionally, in order to prevent the corners from being darkened by the non-light emitting portion 1 a of the fluorescent tube 1, a length extending from the effective light emitting region 1 b of the fluorescent tube 1 to both ends of the light incident surface 2 a of the light plate 2 is used. However, the non-light-emitting portions la and 1a of the fluorescent tube 1 are configured to protrude to the side of the light guide plate 2, and the liquid crystal display device LCD 1 has a wider frame. Had a problem. According to this configuration, the non-light-emitting portions 1 a and 1 a at both ends of the fluorescent tube 1 are provided at both ends of the light incident surface 2 a of the light guide plate 2 by making the notch A of the light guide plate 2 uniform in luminance. The notch A scatters light to prevent uneven brightness of the liquid crystal display panel while reducing the size of the liquid crystal display device. Note that, instead of the lighting device UT1, “the lighting greed of the second and third examples” of the first embodiment and “the lighting devices UT2 and UT of the second embodiment and the application example” according to the second embodiment and the application example. from which may _ή above description with reference to 3 j, those skilled in the art, many modifications and other奚施shaped state of the present invention are apparent. Therefore, the above description, in-out Bae be interpreted as illustrative only Yes, it is provided for the purpose of teaching those skilled in the art the best mode of carrying out the present invention The details of the structure and / or function thereof may be substantially changed without departing from the spirit of the present invention. .

[Possibility of industrial use]

The lighting device according to the present invention is useful, for example, as a backlight for a liquid crystal display device.

INDUSTRIAL APPLICABILITY The liquid crystal display device according to the present invention is useful as a thin display device used for, for example, a notebook personal computer (IP) processor.

Claims

The scope of the claims

1. A light-sensitive plate having a substantially quadrangular shape in plan view and a side surface between a pair of corners constituting a light-entering surface, and a light-emitting portion and a light-emitting portion at both ends and between the ends, respectively. A light source disposed along the light incident surface of the light guide plate, and configured so that light emitted from the light source and incident on the light incident surface of the front ffS light guide plate exits from the upper surface of the light guide plate. In 笸,

The lighting device _c , wherein the light guide plate has a cutout in which a portion of the corner portion corresponding to the non-light emitting portion of the light source is cut out in a plan view.

2. The lighting device according to claim 1, wherein the notch is substantially rectangular or square in plan view.

3. The lighting device according to claim 1, wherein the notch has a shape having a step-shaped notch in plan view.

4. The method according to claim 3, wherein the stepped cutout surface is formed along a straight line extending obliquely from the end of the light emitting portion of the light source so as to pass through the corner portion in plan view. Lighting equipment.

5. The notch is formed such that, in plan view, a vertical surface perpendicular to the front two light incident surfaces and an inclined surface forming an angle of 45 degrees or less with respect to the vertical surface are adjacent to each other and are repeated. 2. The lighting device according to claim 1, wherein the lighting device has a cutout surface.

6, among the corners formed by the vertical surface and the inclined surface of the cutout surface, a corner protruding inward of the light guide plate is, in a plan view, a corner from an end of the light emitting portion of the light source. 6. The lighting device according to claim 5, wherein the lighting device is formed along a straight line that extends obliquely through the lighting device.

7. The lighting device according to claim 1, wherein a light scattering structure that scatters light incident on the notch surface from inside the light guide plate is formed on the notch surface of the notch portion.

8. The lighting device according to any one of claims 1 to 7, further comprising: A liquid crystal display device in which a liquid crystal display panel in which liquid crystal is sandwiched between a pair of substrates is disposed on a light emitting surface side.