JP3417261B2 - Lighting equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a lighting device, and more particularly, to a lighting device in which a light source is disposed at an incident end of a light guide plate and light is emitted perpendicular to the incident end. The present invention relates to an edge-light-type lighting device that emits light from a surface and is suitable for a liquid crystal display device, a main lighting device, a display device such as an illuminated lighting device, an advertising display device, or a guide light. 2. Description of the Related Art A conventional edge light type illumination device is disclosed, for example, in Japanese Patent Application Laid-Open No. 6-27325. As shown in FIG. 12, in this illuminating device, a reflecting plate 9 is provided on one plane of a light guide plate 2 to form a reflecting surface 2b, and a plane parallel to the reflecting surface 2b is a radiating surface 2c. Also,
One end side of these reflection surface 2b and radiation surface 2c is the incident end surface
2a, a linear light source 1 is provided substantially parallel to the incident end face 2a. In this lighting device, a transparent prism sheet 6 having a diffusion layer on the surface is provided on the radiation surface. In such an illuminating device, the light emitted from the light source 1 incident from the incident end face 2a of the light guide plate 2 travels in the light guide plate 2 by total reflection and hits a dot pattern formed on the reflection surface 2b. When the light is diffusely reflected, light having an angle that does not exceed the total reflection angle due to the change in the traveling angle is transmitted and emitted from the emission surface 2c. [0005] Further, this lighting device is characterized in that a transparent prism sheet 6 is provided.
In other words, in a more conventional lighting device that does not have the transparent prism sheet 6, it is conceivable to increase the light amount of the light source 1 in response to many requests to improve the brightness. However, in this case, the size of the light source 1 becomes large, and it becomes difficult to make the lighting device thin and lightweight. In addition, the heat radiation amount of the light source 1 increases, which is not preferable. [0006] Therefore, it is conceivable to distribute the emitted light in one direction so as to increase the luminance when viewed from this direction, thereby increasing the efficiency. Such light distribution control is performed by the transparent prism sheet 6 described above. [0007] However, such a transparent prism sheet 6 has a disadvantage that it is expensive and costly. Also, the use of such a transparent prism sheet 6 increases the number of parts, and it is necessary to pay attention to the direction of the front and back, and to perform the assembly work. Takes
The cost is likely to be high. In addition, the surface of the transparent prism sheet 6 is easily damaged, and if the surface is damaged, there is a problem that the light distribution improving effect is reduced. SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a thin, lightweight, large-area, high-brightness, inexpensive and easy-to-produce edge. An object of the present invention is to provide a light-type lighting device. According to a first aspect of the present invention, there is provided a linear light source, and a light guide plate for emitting light from the light source. The light guide plate 2 has an incident end face 2a on which light from the light source 1 is incident, and the incident end face 2a.
A reflecting surface 2b that reflects incident light, and a flat surface that is substantially parallel to the reflecting surface 2b;
A radiating surface 2c for radiating the reflected light, wherein the light source 1 is disposed substantially parallel to the incident end surface 2a of the light guide plate 2; Gender,
A light distribution control structure for controlling at least a direction parallel to the light source 1 is provided on the incident end face 2a or the reflection face 2b of the light guide plate 2, and is characterized in that it is provided. In such an illuminating device, the light distribution control structure provided on the incident end face 2a controls the direction of light passing through the incident end face 2a, so that the light travels through the light guide plate 2. In this case, the light distribution control structure may be any light transmission control structure that transmits light.
A transparent prism sheet 6 having a prism array-like structure in which a number of protrusions having a large number of substantially triangular cross sections are arranged on the surface may be provided. The light incident from the incident end face 2a and traveling through the light guide plate 2 is reflected with its light distribution controlled by the light distribution control structure provided on the reflection surface 2b, and exits from the radiation surface 2c. Will go. Therefore, it is not possible to control the light distribution of the reflected light by providing the transparent prism sheet 6 on the reflection surface 2b, and to control the light distribution by the shape of the surface of the reflection surface 2b. Will do. As described above, even when the transparent prism sheet 6 is used, only the incident end face 2a is used, and the use area of the expensive transparent prism sheet 6 can be reduced. Further, by forming the light distribution control structure as a surface shape and integrally forming the light guide plate 2, the number of parts is reduced, the structure is simplified, and the device is easy to manufacture. According to a second aspect of the present invention, in the first aspect, a light distribution control structure is provided on the reflection surface 2b, and the light distribution control structure is substantially V-shaped or substantially parallel to the light source 1. A plurality of grooves 3 having a substantially V-shape or a substantially trapezoidal shape are formed on the inner surface of the groove 3 having a substantially V-shaped or substantially trapezoidal shape. The feature is that it consists. In such an illuminating device, the direction of the light reflected by the reflecting surface 2b is controlled by the prism array shape of the prism mirror including the groove 3 and the small groove 3b provided on the reflecting surface 2b. The light distribution of the light emitted from the emission surface 2c is controlled. More specifically, the light distribution in the direction parallel to the light source 1 is controlled by the shape of the small groove 3b, and the light distribution in the direction perpendicular to the light source 1 is controlled by the cross-sectional shape of the groove 3 excluding the small groove 3b. In the invention of the first embodiment, a light distribution control structure is provided on the reflection surface 2b, and the light distribution control structure is formed as a substantially V-shaped or substantially trapezoidal groove 4 so as to be substantially parallel to the light source 1. A plurality of the slopes forming the grooves 4 are arranged in parallel with each other, and all or a plurality of slopes forming the grooves 4 are close to the light source 1 on the end side of the light guide plate 1 so as to be close to the quadratic function, m-order function, error function, sine / It is characterized by being formed by being curved into a curved shape represented by a cosine function or a cycloid. In such an illuminating device, the direction of the light reflected by the reflecting surface 2b is controlled by the prism mirror-like shape including the groove 3 and the small groove 3b provided on the reflecting surface 2b. The light distribution of the light emitted from 2c is controlled. More specifically, the light distribution in the direction parallel to the light source 1 is controlled by the curved shape, and the light distribution in the direction perpendicular to the light source 1 is controlled by the cross-sectional shape of the groove 4. In the invention of the second embodiment, the incident end face 2a
The light distribution control structure is provided on the light source 1.
A plurality of ridges 5 are provided side by side, and the cross-sectional shape of the ridges 5 is formed in a substantially V shape or a substantially semi-cylindrical shape. The angle .alpha.5 formed by the portion is formed at an obtuse angle. In such an illuminating device, a plurality of protrusions 5 arranged side by side on the incident end face 2a have a prism array shape. Therefore, when the projections 5 are reflected by the reflection surface 2b and radiated from the radiation surface 2c, The light distribution in the direction parallel to the light source 1 is controlled.
In this case, since the apex angle α5 of the substantially V-shape of the protruding ridge 5 or the angle α5 formed between the vertex of the substantially semicylindrical shape and both base corners is an obtuse angle, the light emitted from the emission surface 2c is directed in the front direction. The light emitted from the light source 1 changes its direction and passes through the incident end face 2a. The invention according to the second embodiment is characterized in that an apex angle α5 of a substantially V-shape or an angle α5 between an apex of a substantially kamaboko shape and both bottom corners is formed to be an acute angle. I have. In such an illuminating device, since the apex angle α5 of the substantially V-shape of the ridge 5 or the angle α5 between the apex of the substantially semicylindrical shape and the bottom corners is an acute angle, the light radiated from the radiating surface 2c. The light emitted from the light source 1 passes through the incident end face 2a while changing its direction so that the light has a bat wing-type light distribution in a direction spreading to both sides. In the invention of the third embodiment, the incident end face 2a
And a light distribution control structure is formed by providing a transparent prism sheet 6 on the optical disc. In such an illuminating device, when the light passes through the transparent prism sheet 6, the traveling direction of the light is controlled, so that the light distribution of the light radiated from the radiation surface 2c is controlled. In this case, the transparent prism sheet 6
Any material having a small area enough to cover 2a may be used. In the invention of the third embodiment, a light distribution control structure is provided on the reflection surface 2b, and the light distribution control structure is a substantially V-shaped or substantially trapezoidal groove 7, and is substantially parallel to the light source 1. It is characterized by being arranged in parallel. In such an illuminating device, the shape of a prism mirror is formed by the groove 7 provided on the reflection surface 2b, and the direction of the reflected light is controlled. As a result, the light radiated from the radiation surface 2c The light distribution is controlled in a direction perpendicular to the light source 1. Embodiments of the present invention will be described below with reference to the accompanying drawings. [0026] With reference to FIGS. 1 through 3, illustrating a lighting device of the embodiment below. FIG. 1 is a perspective view schematically showing the overall configuration of the lighting device, FIG. 2 is a cross-sectional view schematically showing the lighting device, and FIG. 3 is a perspective view showing an enlarged main part of the lighting device. As shown in these figures, this illuminating device is of an edge light type and includes a linear light source 1 and a light guide plate 2 for emitting light emitted from the light source 1. Such an illuminating device is suitably used for a liquid crystal display device, a main illuminating device, or a display device such as an illuminated illumination device, an advertising display device, or a guide light. The light source 1 is disposed substantially parallel to the incident end face 2a of the light guide plate 2. As the light source 1, a fluorescent lamp, LE
A D array light source or a light source formed by bundling fibers in a line is used. The opposite side of the light source 1 from the light guide plate 2 is covered by a lamp reflector 8. The light guide plate 2 is a translucent substrate.
It is formed from various materials such as synthetic resin such as acrylic resin or glass. The light guide plate 2 has an incident end surface 2a on which light from the light source 1 is incident, a reflecting surface 2b that is one flat surface perpendicular to the incident end surface 2a, and a radiation surface that is substantially parallel to the reflecting surface 2b. Surface 2c. In FIG. 2, reference numeral 9 denotes a high-reflectance white reflector provided on the reflecting surface 2b, which is provided when the lighting apparatus is used as a backlight.
It is not necessary and may not be used in some cases. As shown in FIG. 1 or FIG. 2, in such a lighting device, when light emitted from the light source 1 enters the light guide plate 2 from the incident end face 2a, the light travels through the light guide plate 2 by total reflection. The light reflected at the reflection surface 2b changes its traveling angle and does not exceed the total reflection angle, and is transmitted through the radiation surface 2c and emitted. In this case, the reflecting surface 2b has a substantially V substantially parallel to the light source 1.
A large number of U-shaped grooves 3 are juxtaposed as a light distribution control structure. The reflection surface 2b is finished to a mirror surface, and the light is mirror-reflected on the reflection surface 2b, travels to the radiation surface 2c, and is emitted from the radiation surface 2c. As shown in detail in FIG. 3, small grooves 3b in a direction perpendicular to the light source 1 are formed on the inner surfaces of these grooves 3.
It is formed in a substantially V shape. That is, in this illuminating device, the direction of the light reflected by the reflecting surface 2b is controlled by the prism-mirror shape including the groove 3 and the small groove 3b provided on the reflecting surface 2b. The light distribution of the light emitted from 2c is controlled. More specifically, the light distribution in the direction parallel to the light source 1 (X in FIG. 1) is controlled by the shape of the small groove 3b,
The light distribution in the direction perpendicular to the light source 1 (Y in FIG. 1) is controlled by the cross-sectional shape of the groove 3 excluding the small groove 3b. Therefore, by appropriately forming the shape of the groove 3 and the small groove 3b provided on the reflection surface 2b, both the direction parallel to the light source 1 and the direction perpendicular thereto can be controlled, and the luminance in the controlled direction can be easily increased. Can be improved. When the shapes of the groove 3 and the small groove 3b are specifically exemplified, the cross-sectional shape of the groove 3 is such that the apex angle is 40, 80.
Or 120 degrees (base angles 70, 50 or 30 respectively)
Degree). With such a shape, the light distribution in the direction perpendicular to the light source 1 is controlled as A, B or C, respectively, as shown in FIG. That is, when the apex angle is 40 degrees, the light distribution is in a direction inclined to the light source 1 side, when it is 80 degrees, the light distribution is substantially vertical, and when it is 120 degrees, the direction is away from the light source 1. The light distribution becomes inclined. The groove 3 has a depth of about 35 μm to 80 μm, and is formed so as to be more distant from the light source 1 so that the entire surface has a uniform luminance. I have. Alternatively, the groove 3 may be formed so that the pitch thereof becomes denser as the distance from the light source 1 increases. In this case as well, uniform luminance can be obtained. The shape of the groove 3 is not limited to the V-shape, but may be a substantially trapezoidal shape. Also,
The small groove 3b may have not only a flat slope such as a V-shape or a trapezoid but also a curved slope such as a substantially semi-cylindrical shape. In the above-described lighting device, the reflecting surface 2b has
A light distribution control structure for controlling the light distribution of light emitted from the radiation surface 2c is provided. The light distribution control structure is provided on the incident end surface 2a or the reflection surface 2b of the light guide plate 2, and
What is necessary is just a structure which controls this light distribution control structure at least in a direction parallel to the light source 1. According to such a configuration, when the light distribution control structure is provided on the reflection surface 2b, the light incident from the incident end face 2a and traveling through the light guide plate 2 can be controlled by the light distribution control structure.
The light distribution is controlled and reflected, and comes out from the radiation surface 2c. Therefore, in this case, there is no need to provide the transparent prism sheet 6 on the reflection surface 2b to control the light distribution of the reflected light, and to control the light distribution by the shape of the surface of the reflection surface 2b. Will do. When a light distribution control structure is provided on the incident end face 2a, the direction of light transmitted through the incident end face 2a is controlled by the light distribution control structure so that the light guide plate 2 Continue. In this case, since it is sufficient that the light distribution control structure transmits light, the light distribution control structure has not only the shape of the incident end face 2a but also a number of ridges such as a substantially triangular cross section on the surface. A transparent prism sheet 6 having a juxtaposed prism array-like structure may be provided. In the light distribution control using the light distribution control structure of the incident end face 2a, if the light is diffusely reflected on the reflection surface 2b, the controlled light distribution is lost. become. Therefore, in such a case, the reflection on the reflection surface 2b needs to be configured to perform specular reflection such as total reflection. That is, it is not possible to adopt a configuration in which the reflection plate 9 formed by printing a paint such as titanium white in a dot shape by screen printing or the like is disposed on the reflection surface 2b. By controlling the light distribution of the emitted light as described above, illumination or display with high luminance in a certain direction can be performed. Further, the light distribution control structure has a surface shape,
By being integrally formed with the light guide plate 2, the number of components can be reduced, the configuration can be simplified, and the device can be thin, lightweight, and easy to manufacture. In addition, even when the transparent prism sheet 6 is used, the transparent prism sheet 6 only needs to be disposed on the incident end face 2a, and the expensive transparent prism sheet 6 requires a small area to be used, so that it can be manufactured at low cost. . A first reference example will be described below with reference to FIG. 4A and 4B are views showing the same lighting device, wherein FIG. 4A is a perspective view schematically showing an overall configuration of an example of the same lighting device, and FIG. 4B shows a main part of a different example of the same lighting device. It is a perspective view. As shown in this figure, also in the illumination device, like those of the embodiment is provided with the light distribution property control structure on the reflecting surface 2b. And this light distribution control structure,
A plurality of substantially V-shaped grooves 4 substantially similar to the grooves 3 are provided side by side substantially parallel to the light source 1. But in this case, the small groove
3b is not formed, and instead, all or a plurality of the slopes forming the grooves 4 are formed in a circular or elliptical shape so as to approach the light source 1 on the end side of the light guide plate 2 at the end of the light guide plate 1. Alternatively, it is formed by being curved into a quadratic curve such as a parabola. In the example shown in FIG. 3A, the entire slope of the groove 4 is formed as a continuous curved surface. That is,
The groove 4 is formed in an arc shape in plan view. In the example of (B), the groove 4 is formed in a linear shape in a plan view, and the slope of the groove 4 is divided into small triangular sections, and the grooves 4 are alternately turned upside down and arranged side by side. The section is formed into a curved surface as described above. In the figure, 4a is a flat surface and 4b is a curved surface. In such a lighting device, the light distribution in the direction parallel to the light source 1 is controlled by the quadratic curve shape, and the light distribution in the direction perpendicular to the light source 1 is controlled by the cross-sectional shape of the groove 4. I have. That is, by appropriately forming the groove 4 provided on the reflection surface 2b and the quadratic curve shape of the groove 4, both the direction parallel to the light source 1 and the direction perpendicular thereto can be controlled. The brightness in the direction can be easily improved. It is to be noted that substantially the same effect can be obtained by curving into a curve shape represented by an m-order function, an error function, a sine / cosine function or a cycloid, in addition to the above-described quadratic curve shape. Referring to FIGS. 5 to 10, a lighting device according to a second reference example will be described below. FIG. 5 is a perspective view showing a main part of the lighting device, and FIG. 6 is an enlarged perspective view showing an incident end face 2a side of a light guide plate 2 constituting the lighting device. FIG. 7 is a side view showing an example of light distribution control by the lighting device, and FIG. 8 is a graph showing the light distribution shown in FIG. FIG. 9 is a graph showing different light distributions, and (A) to (C) show examples of different light distributions. FIG. 10 is a perspective view showing an example of the lighting device different from that described above. As shown in FIG. 5, in this illuminating device, a light distribution control structure is provided only on the incident end face 2a, and a plurality of the light distribution control structures are juxtaposed as ridges 5 perpendicular to the light source 1. Things. Although the ridges 5 in this figure are arranged without gaps, they may be provided at intervals, and may have a substantially trapezoidal cross section or a substantially semi-cylindrical cross section instead of a substantially V-shaped cross section. There may be. In the illuminating device having such a configuration, when the light of the light source 1 passes through the incident end face 2a, its traveling direction is controlled by the shape of the ridge 5, and is reflected by the reflecting face 2b and emitted by the radiating face 2c.
When radiated more, the light distribution in the direction parallel to the light source 1 is controlled. Therefore, the brightness in a certain direction parallel to the light source 1 can be improved. As shown in FIG. 10, the reflecting surface 2b also has
A plurality of substantially V-shaped or substantially trapezoidal grooves 7 substantially parallel to the light source 1 serving as a light distribution control structure may be provided in parallel. In this case, the groove 7 provided on the reflection surface 2b forms a prism-mirror shape, and the direction of the reflected light is controlled. As a result, the light radiated from the radiation surface 2c is further transmitted to the light source 1. The light distribution is controlled in the vertical direction. That is, in this lighting device, the light distribution can be controlled in both directions parallel and perpendicular to the light source 1. Also, as shown in FIG. 6, by setting the apex angle of the V-shape of the ridge 5 to about 90 degrees, the butt wings spread to both sides from the front as shown in FIG. 7 or FIG. The light distribution of the mold can be obtained. The light distribution of the bat wing type is as follows.
The cross-sectional shape of the ridge 5 is formed in a substantially V-shape or a substantially semi-cylindrical shape, and an angle α5 between the apex of the substantially V-shape and the apex of the substantially semi-cylindrical shape and both bottom corners is 90 degrees or less. This is obtained by forming an acute angle. Further, as shown in FIG. 9, it is possible to obtain a light distribution in which light is radiated strongly in the front direction. Such light distribution can be obtained by forming the substantially V-shaped apex angle α5 of the ridge 5 or the angle α5 formed by the apex of the substantially semicylindrical shape and both base corners at an obtuse angle. In the case of this figure, the angle α5 is set to 120 degrees in the case of (A), the angle α5 is set to 130 degrees in the case of (B), and the angle α5 is set to 140 degrees in the case of (C). Regardless of the angle α5, the amount of light emitted at an angle within 30 degrees from the front is about twice or more the amount of light emitted outside 30 degrees. Therefore, in this case, as a result of controlling the light distribution in both directions parallel and perpendicular to the light source 1, the brightness in the front direction is further improved. Referring to FIG. 11, a lighting device according to a third reference example will be described below. FIG. 11 shows a configuration of the lighting device,
(A) is a perspective view schematically showing the entire configuration, and (B) is a plan view of a main part. As shown in this figure, in this lighting device, a light distribution control structure is formed by providing a transparent prism sheet 6 particularly on the incident end face 2a. In this case, ridge
The surface on which 10 is formed is provided so as to be substantially in contact with the light guide plate 2 side. As such a transparent prism sheet 6, a part number BEFII / 100 (II represents Roman numeral 2) manufactured by Three M Co., Ltd. is used. Also, on the front of this lighting device, a green guide light sign is printed,
The lighting device is provided with a diffuser plate 11 having an average transmittance of 48%, and is formed so as to be used as a guide light in an emergency or the like. In such an illuminating device, when the light passes through the transparent prism sheet 6, the traveling direction of the light is controlled, so that the light distribution of the light radiated from the radiation surface 2c is controlled. As the transparent prism sheet 6, an incident end face
Any lighting device having a small area enough to cover 2a may be used, and the lighting device is formed inexpensively. In this case, since the surface on which the ridges 9 are formed is directed toward the incident end face 2a of the light guide plate 2, the light distribution is such that a large amount of light is radiated in the front direction, and the front luminance is reduced. 7.6%
Has improved. Note that, by using the transparent prism sheet 6 upside down, it is possible to conversely improve the luminance in the peripheral direction. According to the first aspect of the present invention, since the light distribution of emitted light can be controlled by the light distribution control structure, the edge light system having high luminance in a certain direction. Lighting device. Further, the light distribution control structure has a surface shape,
By being formed integrally with the light guide plate, the number of components is reduced, the structure is simplified, and the device is thin, lightweight, and easy to manufacture. Further, even when a transparent prism sheet is used, the transparent prism sheet may be provided only on the incident end face, and the area required for the expensive transparent prism sheet can be reduced. According to the first aspect of the invention, the light distribution in the direction parallel to the light source is controlled by the shape of the small groove, and the light distribution in the direction perpendicular to the light source is controlled by the cross-sectional shape excluding the small groove from the groove. . That is, by appropriately forming the shape of the groove and the small groove provided on the reflection surface, both the direction parallel to the light source and the direction perpendicular thereto can be controlled, and the luminance in a certain direction can be easily improved. Has become something. ## EQU00003 ##

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view schematically showing an overall configuration of a lighting device according to an embodiment of the present invention. FIG. 2 is a cross-sectional view schematically showing the lighting device of the above. FIG. 3 is an enlarged perspective view showing a main part of the illumination device of the above. FIGS. 4A and 4B are diagrams showing a lighting device according to a first reference example of the present invention, in which FIG. 4A is a perspective view schematically showing an overall configuration of an example of the lighting device, and FIG. It is a perspective view which shows the principal part about the different example of an apparatus. FIG. 5 is a perspective view showing a main part of a lighting device according to a second reference example of the present invention. FIG. 6 is an enlarged perspective view showing an incident end face side of a light guide plate included in the above lighting device. FIG. 7 is a side view showing an example of light distribution control by the above lighting device. FIG. 8 is a graph showing light distribution by the lighting device of the above. FIG. 9 is a graph showing different light distributions by the above lighting device, wherein (A) to (C) show examples of different light distributions. FIG. 10 is a perspective view showing a different example of the lighting device. 11A and 11B show a configuration of a lighting device according to a third reference example of the present invention, and FIG. 11A is a perspective view schematically showing the entire configuration.
(B) is a top view which shows the principal part. FIG. 12 is a sectional view showing a conventional example. [Description of Signs] 1 Light source 2 Light guide plate 2a Incident end face 2b Reflecting surface 2c Radiating surface 3 Groove 3b Small groove 4 Groove 5 Protrusion 6 Transparent prism sheet 7 Groove 8 Lamp reflector 9 Reflector 10 Protrusion 11 Diffuser

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-9-61631 (JP, A) JP-A-9-113907 (JP, A) JP-A-8-29620 (JP, A) JP-A-9-96 145934 (JP, A) JP-A-8-254617 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F21V 8/00 G02F 1/13357 G02B 6/00

Claims (1)

(57) [Claim 1] It comprises a linear light source and a light guide plate for emitting light from the light source, the light guide plate having an incident end face for receiving light from the light source. A plane portion perpendicular to the incident end face, a reflecting surface for reflecting the incident light, and a plane portion substantially parallel to the reflecting surface, having a radiation surface for emitting the reflected light, In a lighting device in which the light source is disposed substantially parallel to the incident end face of the light guide plate, a light distribution control structure that controls the light distribution of light emitted from the radiation surface in at least a direction parallel to the light source, A substantially V-shaped or substantially trapezoidal groove parallel to the light source is formed on the incident end face or the reflection face of the light guide plate.
Several V-shaped or substantially trapezoidal
A small groove in the direction perpendicular to the light source is formed on the inner surface of the
An illuminating device characterized by being provided in a shape or a substantially kamaboko shape .