JP3202908B2 - Lighting equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an edge light type illumination device used for a thin illumination light, an advertisement display device, a guide light, or a back lamp of a liquid crystal display device.

[0002]

2. Description of the Related Art An edge-light type illuminating device is composed of a light guide plate formed of a light transmitting material such as an acrylic plate and having a back surface as a diffuse reflection portion, and one end surface of the light guide plate.
Alternatively, a lamp which is a linear light source facing a plurality of end faces (usually a cold cathode tube lamp is used), and a reflector having a U-shaped or C-shaped cross section for directing light emitted from the lamp toward the end face of the light guide plate. And a back reflector that reflects the light passing through the light guide plate toward the back toward the front,
Light that has entered the light guide plate from the lamp exits from the entire surface of the light guide plate due to reflection by the diffuse reflection portion on the back surface of the light guide plate.

In such an edge light type illuminating device, it is required that the brightness of the surface of the light guide plate be increased while the thickness of the light guide plate is reduced, and that the entire surface be maintained at a uniform brightness. In order to increase the surface brightness of the lamp, it is sufficient that all light emitted from the lamp enters the light guide plate and reaches the diffuse reflector, and in order to maintain uniform brightness, the light diffuses according to the distance from the lamp. The configuration of the reflection unit has been changed. However, there are the following problems here.

That is, a loss due to a solid angle, an incident loss due to total reflection, a loss due to the reflectance of the reflector and the light transmittance of the incident end face of the light guide plate not being 100%, a condensing loss due to the shape of the reflector, and a lamp. Is a loss due to re-absorption of light. In the conventional edge light panel, since the center of the thickness of the light guide plate 1 and the center of the lamp 3 almost match each other as shown in FIG. By directing the same amount of direct light. The direct light directed toward the front surface also travels toward the diffuse reflection portion 2 on the back surface due to total reflection in the light guide plate, but a part of the light is reflected from the front surface when reflected on the front surface, so that a loss occurs. It is desired that the amount of direct light directed toward the diffuse reflection portion 2 on the back surface of the light guide plate 1 be increased.

[0005] The incident loss due to total reflection is such that, of the light emitted from the lamp, incident light having an angle larger than the total reflection angle with respect to the incident end face of the light guide plate has a reflection component more than a component entering the light guide plate. In an edge light panel using a lamp of a linear light source, a large amount of this loss occurs in the longitudinal direction of the lamp. Regarding the light-gathering loss due to the shape of the reflector, the center (focal point) of the arc of the reflector having a U-shaped or C-shaped cross-section coincides with or comes close to the center of the lamp, and the portion on the light guide plate side is the light guide plate Although the light is substantially parallel to the front and back surfaces, in this case, most of the light that goes out of the lamp of the reflection plate and is reflected by the light guide plate and then directed to the light guide plate is totally reflected. Also, even if it enters the light guide plate, it will only reach the diffuse reflection surface near the incident end face of the light guide plate or it will come out directly from the surface near the incident end face of the light guide plate,
Simply increasing the surface brightness near the incident end face of the light guide plate causes more problems in terms of brightness uniformity. In addition, since the portion of the lamp opposite to the portion facing the incident end face of the light guide plate faces the outer peripheral surface of the lamp at a short distance, it is re-entered into the lamp to increase loss due to re-absorption.

In order to reduce such a loss, Japanese Patent Application Laid-Open No. 5-127160 proposes disposing a mirror frame finely divided in the longitudinal direction of the lamp between the lamp and the incident end face of the light guide plate. JP-A-5-289077 proposes to seal the lamp house and the incident end face of the light guide plate and fill the inside with a liquid having a refractive index substantially equal to that of the light guide plate.

[0007]

However, although both of the above are effective in reducing the loss due to the total reflection described above, they cannot reduce the loss due to the solid angle. Also, in the former case, the cost is inevitably increased because the mirror frame is newly provided as described above. In the latter case, the cost must be increased in order to prevent the liquid from leaking. I will invite you.

The present invention has been made in view of such a point, and an object thereof is to provide an edge capable of improving the surface luminance and the luminance uniformity of a light guide plate at a minimum cost. An object of the present invention is to provide a light-type lighting device.

[0009]

According to the present invention, there is provided a light guide plate having a diffuse reflection portion on the back side and a light emission portion on the front side, and a linear light source opposed to an end face of the light guide plate. In an edge-light type illumination device including a lamp and a reflector surrounding the lamp and directing reflected light to the end face of the light guide plate, a lamp having a diameter smaller than the thickness of the light guide plate at the end face side is used as the light guide plate. It is characterized in that it is arranged only in a position close to the surface side in the thickness direction of the light guide plate within the thickness. In this case, as is apparent from FIG. 1, the amount of direct light that goes out of the lamp 3 and goes to the back side of the light guide plate 1 where the diffuse reflection portion 2 is provided is smaller than the amount of direct light that goes to the front side. It can be increased, and the loss due to the solid angle described above can be reduced.

It is also effective to form an end surface of the light guide plate facing the lamp as a surface forming an obtuse angle with respect to the surface of the light guide plate. In addition, a transparent material having a refractive index greater than that of air is sandwiched between the lamp and the reflection plate, a reflection suppressing layer is coated on an end face of the light guide plate facing the lamp, or the light guide plate side of the reflection plate is disposed on the light guide plate. It is also preferable to form the lamp on a plane inclined with respect to the front surface or the back surface, or to arrange the lamp at a position in contact with the end surface of the light guide plate.

The lamp may be an ultraviolet lamp, and a fluorescent paint may be applied to an end face of the light guide plate facing the lamp. A light guide plate having a light diffusing portion on the front side and a light exit portion on the front side thereof, a lamp as a linear light source facing the end surface of the light guide plate, and surrounding the lamp, reflected light and the above-mentioned rear end. In a lighting device of an edge light type having a reflector directed toward an end face, a lamp having a diameter smaller than the thickness of the light guide plate at the end face side is provided within the thickness of the light guide plate and on the back side in the thickness direction of the light guide plate. It only has to be placed at a position closer to it.

Further, it is preferable that the lamp is held by a lamp holding portion integrally extended from a side end of the light guide plate.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. 2. In FIG. 2, a lamp having a cold cathode tube surrounded by a reflector 4 having a U-shaped cross section has one end faced. The light plate 1 has a wedge-shaped cross section made of a transparent acrylic resin having a high light transmittance. The end surface having the maximum thickness faces the lamp 3, and a dot pattern is printed or integrally formed on the back surface thereof. The reflective plate 6 is provided on the rear surface while the diffuse reflection unit 2 is provided. A display surface / diffusion plate 7 made of a milky white acrylic plate is arranged on the surface of the light guide plate 1. The lamp 3 is a light guide plate 1
Within the thickness of the light guide plate 1 in the thickness direction.

In this case, of the light emitted from the lamp 3 and directed to the one end face (incident end face) of the light guide plate 1, the amount of direct light directed to the back side of the light guide plate 1 is smaller than the amount directed to the front side. The light guide plate 1 has a wedge-shaped cross section so that light can easily reach the back as viewed from the lamp 3, and the configuration of the diffuse reflection portion 2 can be changed from the lamp 3. In addition to the change according to the distance (this configuration is not shown because various conventional ones can be used), the uniformity of the luminance of the display surface can be improved. In addition, an improvement in luminance as a whole can be obtained.

FIG. 3 shows another example. Here, the angle α between the incident end face of the light guide plate 1 and the surface of the light guide plate 1 is set to be an obtuse angle. In this case, as compared with the case where the angle α is a right angle, the amount of light emitted from the lamp 3 and distributed directly to the diffuse reflection portion 2 on the back surface side of the light guide plate 1 can be further increased. In addition, it is possible to improve the luminance of the surface of the light guide plate 1 and at the same time, it becomes easy to control the uniformity of the luminance distribution on the surface by the diffuse reflector 2. In addition, when the incident end surface is the inclined surface as described above, the lamp 3 may be at a position indicated by a chain line.

In FIG. 4, a flexible sheet-like transparent material 8 having a higher refractive index than air is sandwiched between the reflector 3 and the side of the lamp 3 not facing the light guide plate 1. Now, if the transparent material 8 is formed of a sheet made of the same acrylic resin as the light guide plate 1, the total reflection angle when the light goes from the air to the acrylic resin is 82 °, whereas the acrylic resin is converted to the air. The angle of total reflection when light is directed is 42
Since the light enters the transparent member 8 at an angle of 42 ° or more, the light repeatedly travels inside the transparent member 8 repeatedly, and then travels from the end face of the transparent member 8 toward the light guide plate 1. Thus, it is possible to reduce the re-absorption loss of the light reflected by the reflector 4 toward the lamp 3 due to the lamp 3.
As shown in FIG. 5, the transparent member 8 may be formed by binding plastic optical fibers in a sheet shape. In this case, each of the optical fibers intersects with the longitudinal direction of the lamp 3 and the lamp 3 and the reflector 4 are connected to each other. Place between.

In order to suppress the reflection occurring at the incident end face of the light guide plate 1, a material having a smaller refractive index than that of the light guide plate 1, for example, magnesium fluoride (having a refractive index of 1.38) is １ ／.
If the reflection suppressing layer 9 formed by coating with a wavelength thickness is formed on the incident end face of the light guide plate 1 as shown in FIG. 6, even better results can be obtained. The reflectance on the acrylic resin surface when the antireflection layer 9 is not provided is about 4% in the case of normal incidence, and the reflected light component in the case of oblique incidence increases further. The reflectance on the surface can be suppressed to 2% or less, and the reflectance can be further suppressed if the reflection suppressing layer 9 is a so-called multi-coat.

The reflecting plate 4 should not be U-shaped or C-shaped in cross section, but should be flat at both ends and inclined with respect to the back surface of the light guide plate 1 as shown in FIG. . Of the light that enters the light guide plate 1 after being reflected by the reflection plate 4, the amount of light traveling toward the back side and the back side of the light guide plate 1 can be increased. Also, as shown in FIG.
Is brought closer to the incident end face, preferably, if it is brought into contact with the incident end face, not only the direct light but also the reflected light from the reflecting plate 4 can be more efficiently condensed and incident on the back side of the light guide plate 1 and in the depth direction. As a result, the uniformity of luminance on the display surface can be improved.

FIG. 9 shows another example. Here, an ultraviolet lamp is used as the lamp 3, and the reflector 4 is not mirror-finished with silver, but is a mirror-finished aluminum which is effective in reflecting ultraviolet rays. Further, a fluorescent paint 5 is applied to the incident end face of the light guide plate 1. The visible light output from the fluorescent paint 5 is caused to enter the light guide plate 1 by the ultraviolet light, so that the efficiency of the visible light incident on the light guide plate 1 is increased.

Also in this case, when the incident end face of the light guide plate 1 is formed at an obtuse angle with respect to the front surface as shown in FIG. Since the surface area can be increased, the surface brightness can be improved. By the way, if the application of the edge light type illumination device does not require a fine resolution like an indicator lamp, the diffusion portion 2 ′ is formed as a light emitting portion of the light guide plate 1 as shown in FIG. May be arranged such that only the reflection plate 6 is arranged on the back side, but in this case, the lamp 3 is displaced toward the back side within the thickness of the light guide plate 1. Then, the diffusion unit 2 '
The amount of direct light to the can be increased.

In any case, as shown in FIG. 12, if both ends of the lamp 3 are held by holding portions 15 extending from both ends of the light guide plate 1, respectively, The holding structure can be simplified, and the lamp 3 can be reliably disposed at a position advantageous for improving the surface brightness of the light guide plate 1 and the brightness uniformity.

[0022]

As described above, according to the present invention, since the lamp is disposed only in the thickness of the light guide plate and at a position closer to the surface side in the thickness direction of the light guide plate, the light guide plate exits from the lamp. The amount of direct light going to the back side where the diffuse reflection portion is provided can be made larger than the amount of direct light going to the front side, so that the loss due to the solid angle can be reduced. This is advantageous for improving the surface brightness and the uniformity of the brightness of the light guide plate, and can be kept thin because the overall thickness can be kept within the thickness of the light guide plate. .

If the end face of the light guide plate facing the lamp is formed as a surface that forms an obtuse angle with respect to the surface of the light guide plate, the amount of direct light traveling toward the back side where the diffuse reflection portion is provided can be reduced. It is possible to further increase the surface luminance and improve the luminance uniformity. If a transparent material whose refractive index is larger than air is sandwiched between the lamp and the reflector, the amount of light that is re-absorbed by the lamp can be suppressed, and the surface brightness of the light guide plate will also be higher. Even if the reflection-suppressing layer is coated on the end face of the light guide plate facing the lamp, the surface brightness of the light guide plate can be similarly improved.

Furthermore, if the light guide plate side of the reflector is formed as a plane inclined with respect to the front surface or the back surface of the light guide plate, light reflected by the reflector and traveling toward the light guide plate is transmitted to the back surface side and the back side of the light guide plate. Therefore, the brightness and the uniformity of the brightness can be improved. Even when the lamp is arranged at a position in contact with the end face of the light guide plate, it is possible to improve the brightness by increasing the amount of light incident on the light guide plate and to increase the amount of light reaching the depth of the light guide plate. Therefore, the uniformity of luminance can be improved.

When the lamp is an ultraviolet lamp and the end surface of the light guide plate facing the lamp is coated with a fluorescent paint, the end surface of the light guide plate becomes a secondary light emitting surface for outputting visible light, so that visible light is emitted. Is guided in the light guide plate. A light guide plate having a light diffusing portion on the front side and a light exit portion on the front side thereof, a lamp as a linear light source facing the end surface of the light guide plate, and surrounding the lamp, reflected light and the above-mentioned rear end. In a lighting device of an edge light type having a reflector directed toward an end face, a lamp having a diameter smaller than the thickness of the light guide plate at the end face side is provided within the thickness of the light guide plate and on the back side in the thickness direction of the light guide plate. By arranging only at a position closer to the position, it is possible to increase the amount of direct light going to the light diffusion part, reduce the loss due to the solid angle, improve the luminance and improve the uniformity of the luminance, and as a whole Can be kept within the thickness of the light guide plate, so that it can be kept thin.

If the lamp is held by the lamp holding portion integrally extended from the side end of the light guide plate, the lamp holding structure can be simplified, the cost can be reduced, and the lamp can be reduced. The light guide plate can be reliably held at an advantageous position in terms of improving the surface luminance.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of the present invention.

FIG. 2 is a sectional view of an example of the embodiment.

FIG. 3 is a sectional view of another example of the above.

FIG. 4 is a sectional view of another example of the above.

FIG. 5 is a perspective view showing another example of the above transparent material.

FIG. 6 is a sectional view showing another example.

FIG. 7 is a sectional view showing still another example.

FIG. 8 is a sectional view showing another example.

FIG. 9 is a cross-sectional view showing another example.

FIG. 10 is a sectional view showing still another example.

FIG. 11 is a cross-sectional view of another example.

FIG. 12 is a perspective view showing an example of a lamp holding structure.

FIG. 13 is an explanatory diagram of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light-guide plate 2 Diffuse-reflection part 3 Lamp 4 Reflector

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI G02F 1/13357 G09F 9/00 336J G09F 9/00 336 G02F 1/1335 530 (56) References JP-A-7-182909 (JP) JP-A-4-355429 (JP, A) JP-A-6-174935 (JP, A) JP-A-7-248495 (JP, A) JP-A-3-280079 (JP, A) 4-122912 (JP, A) JP-A-4-102888 (JP, A) JP-A-7-41849 (JP, U) JP-A-3-75476 (JP, U) Registered utility model 3016786 (JP, U) (58) Field surveyed (Int.Cl. ⁷ , DB name) F21V 8/00 F21V 7/22 G02B 6/00 G02F 1/13357 G09F 9/00

Claims (9)

(57) [Claims] 1. A light guide plate having a diffuse reflection portion on a back surface side and a light emission portion on a front surface side, a lamp as a linear light source facing an end surface of the light guide plate, and reflecting light surrounding the lamp. In a lighting device of an edge light type, comprising a reflecting plate directed to the end face of the light guide plate, a lamp having a diameter smaller than the thickness of the light guide plate at the end face side is provided within the thickness of the light guide plate and in the thickness direction of the light guide plate. An illuminating device, wherein the illuminating device is provided only at a position closer to the front side. 2. The lighting device according to claim 1, wherein an end face of the light guide plate facing the lamp is formed as a surface forming an obtuse angle with respect to the surface of the light guide plate. 3. The lighting device according to claim 1, wherein a transparent material having a refractive index higher than that of air is sandwiched between the lamp and the reflector. 4. The lighting device according to claim 1, wherein an end face of the light guide plate facing the lamp is coated with a reflection suppressing layer. 5. The lighting device according to claim 1, wherein the light guide plate side of the reflection plate is formed as a plane inclined with respect to the front surface or the back surface of the light guide plate. 6. The lighting device according to claim 1, wherein the lamp is disposed at a position in contact with an end surface of the light guide plate. 7. The lighting device according to claim 1, wherein the lamp is an ultraviolet lamp, and a fluorescent paint is applied to an end surface of the light guide plate facing the lamp. 8. A light guide plate having a light diffusing portion on the front surface side and having a light emitting portion on the front surface side, a lamp as a linear light source facing an end face of the light guide plate, and reflecting light surrounding the lamp. An edge light type illumination device comprising a reflector directed toward the end face at the rear end, wherein a lamp having a diameter smaller than the thickness of the light guide plate at the end face side is provided within the thickness of the light guide plate and in the thickness direction of the light guide plate. At a position closer to the back side
A lighting device characterized in that the lighting device is arranged only in the lighting device. 9. The lighting device according to claim 1, wherein the lamp is held by a lamp holding portion integrally extended from a side end of the light guide plate.