JPH09204809A - Luminaire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a luminaire having good machining and assembling workability and the enhanced uniformity of luminance. SOLUTION: A fluorescent tube 3 is arranged on the underside of a reflection frame 2 with a high light reflectance. A groove 6a which contains the fluorescent tube 3 is formed on the reverse side of a light guide plate 6 and a curved recess groove 6e is also formed on the surface of the light guide plate 6. A stain finish processing layer 6d is formed in each groove. Moreover, a diffusion reflection layer is formed on the surface except for the groove 6a on the reverse side of the light guide plate 6, and is also formed on the surface where the curve of the recess groove 6e changes into a straight line. A diffusion plate 1 which covers the surface of the light guide plate 6 is placed on the opening part of the reflection frame 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illuminating device for displaying a display object by illuminating a display object from the rear by making a light source a surface emitting a light source.

[0002]

2. Description of the Related Art FIGS. 7 to 8 show a conventional embodiment. FIG. 7 is a partially cutaway perspective view showing a conventional lighting device disclosed in Japanese Patent Application Laid-Open No. 2-208631. In FIG. 7, reference numeral 2 denotes a surface on which a bottom surface portion, a side surface portion and an end surface portion are formed and which faces the bottom surface portion. , A U-shaped groove 6a of the fluorescent tube 3 is formed on the surface contacting the bottom surface of the reflection frame 2,
Moreover, the diffuse reflection layer 6b is formed on the surface in contact with the bottom surface and the side surface.
And a diffusing layer 6d with a satin finish on the top of the U-shaped groove 6a
Is formed, and the portion 6c on the front surface side has a curved concave surface portion at the portion facing the fluorescent tube 3. 1
Is a diffuser plate that covers the reflection frame 2 with a thick portion 1 a that faces the fluorescent tube 3 that is disposed on the front surface side of the light guide plate 6.
FIG. 8 is a cross-sectional view showing a conventional lighting device disclosed in JP-A-1-107236. In FIG. 8, 6 is a U-shaped groove for accommodating the light source 3 on the side opposite to the light emitting surface. The light guide plate is provided with a light reflector 7 on the surface excluding the light exit surface, and is fixed to a housing 8 whose light exit surface side is open. Reference numeral 9 denotes an optical screen which is closely fixed to the light emitting surface, and 1 denotes a diffusion plate which covers the light guide plate 6 and the housing 8.

Next, the operation of the prior art will be described. Both FIG. 7 and FIG. 8 are surface illumination devices using a so-called direct type light guide system in which a light source is arranged in an effective light emitting area. The fluorescent tube 3 is arranged in the reflection frame 2, and a U-shaped groove 6a is provided on the surface in contact with the bottom surface of the reflection frame 2. The fluorescent tube 3 is turned on in the groove 6a, and the emitted light is incident on the inside 6 of the light guide plate through the groove 6a. The radiated light propagates in the plane parallel direction in the light guide plate, and repeats irregular reflection on the back surface and the side surface of the light guide plate 6 surrounded by the reflection frame. Of the irregularly reflected light rays, light having a critical angle or more with respect to the surface of the light guide plate 6 is repeatedly reflected, but light having a critical angle or less is emitted from the surface of the light guide plate and irradiates the diffusion plate 1 from behind. Further, the radiated light of the fluorescent tube is not propagated by the light guide plate 6, but is directly transmitted to the surface of the light guide plate and irradiates the diffuser plate 1 from behind. Since the direct transmitted light is stronger than the diffusely reflected light propagating in the light guide plate 6, the diffusion layer 6d and the optical screen 9 suppress the intensity of the light and make the intensity of irradiation to the diffusion plate uniform. The brightness distribution on the surface of the diffusion plate is made uniform.

[0004]

However, in the above-mentioned conventional lighting device, the light directly transmitted to the surface of the light guide plate is suppressed by the thick portion of the diffuser plate or the optical screen to make the intensity of irradiation to the diffuser plate uniform. Therefore, it is necessary to partially form the diffuser plate with a thick wall, and when manufacturing the diffuser plate by injection molding, there is a difference in the cooling time with the thin part and there are problems such as pitting on the surface of the diffuser plate. was there. Further, the optical screen is a point-shaped opaque body processed into a polyester film by a vacuum vapor deposition method, and the opaque body has a high density immediately above the light source and becomes low as it is separated, and is fixed to the light guide plate by adhesion. There are problems that a uniform luminance distribution cannot be obtained due to a deviation at the time of adhering to the light source position, assembly workability of adhering is poor, and cost of parts of the optical screen is high.

Further, since it is necessary to provide a light reflector having an improved light reflection efficiency on the inner surface of the reflecting frame, the number of parts is large and the assembling property is poor.

Further, depending on the light reflector, there is a problem that light can be seen through the outside.

The present invention has been made in order to solve the above-mentioned problems, and eliminates the need for a thick portion of a diffusion plate for suppressing light, an optical screen, and a light reflector on the inner surface of a reflection frame. It is an object of the present invention to provide an illuminating device that can achieve good display quality and can eliminate the transmission of light to the back surface of the reflective frame.

[0008]

In the illuminating device according to the present invention, there is provided an opening formed of a light-reflecting bottom surface portion and a light-reflecting side surface portion provided upright at an end portion of the bottom surface portion. The reflection frame, the light source disposed on the bottom surface of the reflection frame, the back surface portion that is attached to the reflection frame and has a groove for housing the light source, and the front surface portion that faces the back surface portion. A light guide plate that is emitted from the surface portion, and a diffuser plate that is arranged so as to face the light guide plate and cover the opening of the reflection frame, and diffuse the light emitted from the light guide plate to make surface emission. A diffuse reflection layer having an area density increased as the distance from the light source is increased is provided on the back surface and the surface of the light guide plate.

Further, the surface portion of the light guide plate facing the light source is formed into a curved surface having a concave portion, and the diffuse reflection layer having an area density increased as the distance from the light source is increased to a portion where the curved surface of the concave portion is a plane parallel to the bottom surface portion. Is provided.

The reflecting frame is made of titanium oxide in an amount of 16 to 30%.
It was included.

Further, the reflecting frame is such that the portion facing the light source has a substantially triangular shape.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1. An embodiment of a lighting device according to the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a lighting device of the present invention, and FIG. 2 is a partial sectional perspective view of the lighting device. In the figure, 2 is a white plastic injection-molded product containing 16 to 30% of titanium oxide that has excellent light reflection efficiency and does not allow light to pass through to the back side. It is a reflective frame whose surface facing to is opened. Reference numeral 3 denotes a fluorescent tube which is a light source arranged in parallel with the bottom surface side of the reflection frame 2. Reference numeral 6 denotes a light guide plate which is made of a transparent material such as methacrylic resin or glass and has a U-shaped groove 6a for accommodating the fluorescent tube 3, and 6b diffuses light to a surface of the light guide plate 6 which is in close contact with the bottom surface of the reflection frame 2. It is a diffuse reflection layer for scattering.

The diffusive reflection layer 6b has a pattern shown in FIG. 3 and is provided so that a portion near the light source is rough and becomes denser as the distance from the light source increases. A diffusing material such as magnesium carbonate or barium sulfate is used. There is a method such as silk-screening with the ink that contains ink, or a method of applying satin treatment or roughening the light guide plate. A satin-finished layer 6d is provided on the ceiling part of the groove in which the fluorescent tube 3 is housed, and the satin-finished layer 6d is formed in the curved concave groove 6e on the surface side of the light guide plate 6 facing the fluorescent tube 3.
d is provided. The surface 6c of the light guide plate is a smooth transparent surface, and in the portion where the curved concave groove 6e changes to a straight line,
The diffuse reflection layer 6b having the pattern of FIG. 3 is formed in which the area density becomes coarse to dense as the distance from the fluorescent tube 3 increases.
The surface portion 6c shown in FIG. 1 is a curved surface, which is a curved surface separated from the fluorescent tubes 3 and having a recess between the fluorescent tubes 3.
Although the weight is reduced and unnecessary portions are thinned to improve moldability, the curved surface may be a flat surface. The diffusing plate 1 is formed of a material containing a diffusing material as a function of diffusing light, and the light guide plate side and the surface side are roughened by a satin finish.

Next, a description will be given of the fact that the reflection frame 3 has a titanium oxide content of 16 to 30% so that the reflection frame 3 has excellent light reflection efficiency and prevents transmission of light to the back side. The content of this titanium oxide is the result of an experiment to determine the relationship between the content of titanium oxide and the reflectance and transmittance of light,
FIG. 4 shows the relationship between the content of titanium oxide and the reflectance and transmittance of light. In the figure, the content of titanium oxide is 16%
If it is less than 1.0, the amount of light to the diffusion plate 1 is insufficient, and the light of the fluorescent tube 3 is transparent to the outside of the reflection frame 2 and becomes unsightly. If the content of titanium oxide exceeds 30%, the reflectance is high and the fluorescence is high. The light of the tube 3 is not transmitted to the outside of the reflection frame 2, and the amount of light to the diffuser plate 1 is increased. However, if a large amount of titanium oxide is contained, problems such as deterioration of formability and brittleness of the material of the reflective frame 2 occur. Therefore, the content of titanium oxide is 16 to
30%.

Next, the operation will be described. The light emitted from the fluorescent tube 3 enters through the U-shaped groove 6a and is taken into the light guide plate. In the light guide plate, the light is roughly classified into light that enters the diffuse reflection layer 6b, light that enters the transparent smooth surface, and light that enters the satin finish layer 6d. The light incident on 6b is changed to scattered diffused light in the diffuse reflection layer 6b, is reflected again on the bottom surface, side surface, and end surface of the reflection frame 2, and is irradiated to the diffusion plate 1 from the rear. The light incident on the transparent smooth surface has air at the interface and a refractive index of 1, and the refractive index of the methacrylic resin of the light guide plate is 1.49. According to Snell's law, Sin ^-1 (n1 / n2) = 42 ° 09 of the critical angle. ′
If the incident angle is 19 "or more, the light is repeatedly reflected and totally guided at the interface, and eventually enters the diffuse reflection layer to be changed to scattered diffuse light. Also, if the critical angle is 42 ° 09'19" or less. For example, the light is emitted to the outside of the light guide plate and the diffusion plate 1 is irradiated from the rear side. The light incident on the satin-finished layer 6d is changed to scattered / diffused light, and is further changed to scattered / diffused light at the satin-finished layer 6d on the light guide plate surface side, and the diffuser plate 1 is irradiated from the rear side.

As described above, it is not necessary to partially thicken the diffuser plate, an optical screen and a reflector are not required, and the number of parts is reduced, and the assembly workability can be improved without a recess during injection molding. it can. In addition, the brightness of the light emitting surface of the diffusion plate is improved, and it is possible to prevent the transmission of light to the back surface of the reflection frame.

The above embodiment shows the case where the number of the fluorescent tubes 3 is two, but the fluorescent tube 3 can be constructed by one as shown in FIG.
The same effects as those of the above-described embodiment can be obtained.

Embodiment 2. FIG. 6 is a cross-sectional view of essential parts showing another embodiment of the present invention. The bottom surface of the reflection frame 2 facing the fluorescent tube 3 is a triangular convex portion. According to this, the luminous flux of the fluorescent tube 3 is reflected by the triangular convex portion and does not return to the fluorescent tube 3, and the amount of light incident on the light guide plate is increased, so that the brightness of the light emitting surface is improved and the light on the back surface of the reflecting frame is You can eliminate the transparency.

[0019]

Since the present invention is constructed as described above, the following effects can be obtained.

A reflection frame having an opening formed of a light-reflecting bottom surface portion and a light-reflecting side surface portion erected at an end of the bottom surface portion, and a reflection frame disposed on the bottom surface portion of the reflection frame. A light source, a light guide plate that is mounted on the reflection frame, has a back surface part having a groove for housing the light source, and a front surface part that faces the back surface part, and that emits light of the light source from the front surface part. , A diffusion plate disposed so as to cover the opening of the reflection frame and diffusing the light emitted from the light guide plate to generate surface emission, and the area of the back surface and the front surface of the light guide plate as the distance from the light source increases. Since the diffuse reflection layer having the increased density is provided, it is not necessary to partially increase the thickness of the diffuser plate, the number of parts can be reduced, the molding can be easily performed, and the assembling workability can be improved. In addition, the brightness of the light emitting surface of the diffusion plate is improved, and it is possible to prevent the transmission of light to the back surface of the reflection frame.

Further, the surface portion of the light guide plate facing the light source is formed into a curved surface having a concave portion, and in the portion where the curved surface of the concave portion becomes a plane parallel to the bottom surface portion, the diffuse reflection layer whose area density increases as the distance from the light source increases. Since the above is provided, the processing portion of the diffuse reflection layer can be reduced, and the light guide plate can be lightened.

Further, the reflection frame is made of titanium oxide of 16 to 30%.
Since it is contained, it is possible to improve the luminance of the light emitting surface of the diffusing plate and to prevent the transmission of light to the outside of the reflecting frame.

Further, since the reflecting frame has a substantially triangular shape in the portion facing the light source, the luminance of the light emitting surface is improved and the light transmission on the rear surface of the reflecting frame can be eliminated.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a lighting device according to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional perspective view showing a lighting device according to an embodiment of the present invention.

FIG. 3 is a diagram showing a pattern of a diffuse reflection layer of the present invention.

FIG. 4 is a diagram showing the relationship between the content of titanium oxide and the reflectance and transmittance of light in the reflecting frame of the present invention.

FIG. 5 is a sectional view showing an illumination device according to an embodiment of the present invention.

FIG. 6 is a cross-sectional view of an essential part showing a lighting device according to another embodiment of the present invention.

FIG. 7 is a partial cross-sectional perspective view showing a conventional lighting device.

FIG. 8 is a cross-sectional view showing another conventional lighting device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Diffusion plate, 2 Reflection frame, 2a Triangular convex part, 3 Fluorescent tube, 6 Light guide plate, 6a groove, 6b Diffuse reflection layer, 6c Light guide plate surface, 6d Matte treatment layer, 6e Recessed groove.

Claims (4)

[Claims] 1. A reflection frame having a light-reflecting bottom surface portion and an opening portion having a light-reflecting side surface portion provided upright at an end of the bottom surface portion, and a reflection frame disposed on the bottom surface portion of the reflection frame. A light source, and a light guide plate that is mounted on the reflection frame and has a back surface part having a groove for accommodating the light source and a front surface part facing the back surface part, and that emits light of the light source from the front surface part. A diffuser plate facing the light guide plate, covering the opening of the reflection frame, and diffusing light emitted from the light guide plate to make surface emission. An illuminating device characterized in that a diffuse reflection layer having an area density increased with increasing distance from the light source is provided on a surface portion. 2. A surface area of the light guide plate facing the light source is a curved surface having a concave portion, and an area density increases as the curved surface of the concave portion becomes a plane parallel to the bottom surface portion as the distance from the light source increases. The lighting device according to claim 1, further comprising a diffused reflection layer. 3. The reflection frame is made of titanium oxide of 16 to 30%.
The lighting device according to claim 1, wherein the lighting device is contained. 4. The illumination device according to claim 1, wherein a portion of the reflection frame facing the light source has a substantially triangular shape.