JP3008932B2 - Back lighting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight device used for a display or the like, and more particularly, to a backlight device for effectively illuminating a rear surface with simple means.

[0002]

2. Description of the Related Art First, a conventional backlight device will be described with reference to FIG.

FIG. 6 is a schematic diagram showing the configuration of a conventional backlight device. This device includes a linear light source 4, a reflector 6 for effectively reflecting light from the light source, a light guide plate 1 for irregularly reflecting light, a sheet-like reflecting member 8 for reflecting light on the back surface of the light guide plate 1, and a light source. And a sheet-like diffusion member 7 for diffusing or condensing the light. Dots or linear patterns 2 for irregularly reflecting light from the light source 4 are often formed on the back surface of the light guide plate 1 by printing, machining, molding, or the like. Is a plane.

As another conventional example, Japanese Utility Model Application Laid-Open No. 62-7
No. 4282, a surface illumination device (conventional example 1),
Japanese Patent Application Laid-Open No. 9-231822 discloses a side light type surface light source device (conventional example 2).
Surface light source device described in Japanese Patent Application Laid-open No.
There is a lighting device described in Japanese Patent Application Laid-Open No. 145934 (hereinafter referred to as Conventional Example 4).

First, the conventional example 1 is characterized in that a concave and convex surface having a concave lens function such that the spectral distribution in a direction parallel to the longitudinal direction of the rod-shaped light source becomes uniform is provided on the opposite surface of the rod-shaped light source. It is.

Next, the second conventional example has the same object as the first conventional example, and is characterized in that an illumination light introduction portion from a light source is provided, thereby collecting light near a non-light emitting portion. It is.

Next, the third conventional example is characterized in that light is collected near a non-light emitting portion via a triangular prism.

Next, Conventional Example 4 is aimed at improving the surface luminance of the light guide plate at a minimum cost, and is an application filed by the same company as Conventional Example 1. It is devised and can be considered as the evolution system of Conventional Example 1.

[0009] Of the above-mentioned conventional examples, the surface lighting apparatus of the conventional example 1 will be further described. This device is composed of a rectangular light guide plate and a rod-shaped light source composed of a straight tube fluorescent lamp arranged opposite to one side surface of the light guide plate, and the light from the rod-shaped light source introduced from one side surface of the light guide plate. A surface parallel to the longitudinal direction of the rod-shaped light source of light passing through the light guide plate on the surface of the light guide plate facing the rod-shaped light source in a surface lighting device having a reflection surface that appropriately reflects light on the front surface side formed on the back surface side of the light guide plate. Is a surface lighting device having an uneven surface having a concave lens function such that the spectral distribution of the light is uniform.

[0010] Further, among the above-mentioned conventional examples, the illumination device of the conventional example 4 will be further described. This apparatus is an apparatus which aims to improve the surface luminance of the light guide plate at a minimum cost. As a configuration, a light guide plate having a diffuse reflection plate on the back side and a light oblique portion on the front side, and at least an end face of the light guide plate facing the lamp in the light guide plate, surrounding the lamp at the end face of the light guide plate. The projections and depressions have a triangular cross section in the longitudinal direction of the lamp. When the surface facing the lamp is a flat surface, it is a device that can also enter light that does not enter the light guide plate due to total reflection.

[0011]

However, in the above-described conventional example, it is difficult to guide the light from the light source 4 to the light guide plate 1 near the electrode portion of the light source 4 and the non-light emitting portion. Alternatively, the light source 4 is used only for irregular reflection by the linear pattern 2.
Since it is difficult to spread the light from the light guide plate 1 over the entire light guide plate 1, there is a problem that the light is partially dark and unevenness is conspicuous.

In order to solve the above problem, it is necessary to make the light source 4 longer than the display area of the display.
There is a problem that the non-light emitting portion of the light source 4 protrudes from the display area, making it difficult to reduce the size of the display.

[0013] Accordingly, an object of the present invention is to provide a backlight device which can eliminate luminance unevenness in the vicinity of a non-light-emitting portion in order to solve the above problem.

[0014]

In order to achieve the above object, a backlight device according to the present invention comprises a linear light source, a socket for holding the linear light source, and a reflector for effectively reflecting light from the linear light source. And, a light guide plate that diffusely reflects light, provided on the back surface of the light guide plate, a sheet-like reflection member that reflects light, and a sheet-like diffusion member that diffuses or condenses light,
The linear light source has a shorter overall length than the light guide plate,
An end face on the light source side of the light guide plate has a refraction portion for refracting light from the light source, and the light guide plate has the bent end face near the light source.
When the light source enters the light guide plate from the refraction unit, the light source is refracted by the angle of incidence on the refraction unit, and the non-light-emitting unit of the light source of the light guide plate is provided by the reflection diffusion unit. It is characterized in that luminance unevenness in the vicinity can be eliminated.

[0015] The refracting portion may have a shape of the light emitting portion near the electrode portion and the non-light emitting portion of the light source such that light from the light source is refracted in the direction of the electrode portion and the non-light emitting portion. preferable.

Further, the shape is not more than the length from the side end surface of the light guide plate to the center side end surface of the non-light emitting portion of the lamp.
And a refraction section on the end face of the light guide plate where the socket contacts.
It is preferable not to provide them.

Furthermore, it is preferable that the refracting portion is formed in a plurality of substantially triangular shapes whose sides on the side end surface side of the light guide plate are long with respect to the longitudinal direction of the light source.

Preferably, the shape of the refracting portion is formed by a semicircular or elliptical curve and a straight line.

Further, it is preferable that the angle between the tangent drawn at the start point on the end face side of the light guide plate having a semicircular or elliptical curve and the straight line of the refraction portion is an obtuse angle.

Still further, in the refracting portion, approximately three adjacent
It is preferable that the angle between the sides of the angular shape is an obtuse angle (90 ° or more).

When the light from the light source enters the light guide plate from the refraction part, it is preferable that the light is refracted by the angle of incidence on the refraction part based on Snell's law.

Further, it is preferable that the depth of the refraction portion from the end face of the light guide plate is gradually reduced as it approaches the side end face of the light guide plate.

[0023]

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram showing the configuration of an embodiment of the backlight device of the present invention. (A) is a front view,
(B) is a side view. This device comprises a linear light source 4, a reflector 6 for effectively reflecting light from the light source, a light guide plate 1 for irregularly reflecting light, a sheet-like reflecting member 8 for reflecting light on the back surface of the light guide plate 1, and a light source. And a sheet-like diffusion member 7 for diffusing or condensing the light. A light source 4 is provided on the back surface of the light guide plate 1.
Dots or linear patterns 2 for irregularly reflecting light from the substrate are formed by printing, machining, molding, or the like. The light source 4 is held by a socket 5, which is arranged so as to overlap the end surface 3 of the light guide plate 1. On the light source side end face 3 of the light guide plate 1, the shape of the electrode part of the light source 4 and the shape of the light emitting part near the non-light emitting part are set such that the light from the light source 4 is directed to the outside of the display (the side end face direction of the light guide plate 1).
It is shaped to be refracted. This shape corresponds to the light guide plate 1
Is formed on the end face 3 of the light guide plate 1 with a length (Y) equal to or less than the length (X) from the side end face to the center end face of the non-light emitting portion of the lamp. Further, a shape similar to the above-described shape is formed on a side end surface of the light guide plate 1 near the light source 4, and the light reflection / diffusion member 10 is attached or applied to the surface. The shape of the light source side end face 3 of the light guide plate 1 is basically the same as that of the light guide plate.
1 is a long triangle on the side end face side , and this side and the light guide plate 1
The angle A between the side edge of the triangle and the side of the triangle that contacts
0 ° or more).

FIG. 2 is an enlarged view showing an end face on the light source side according to the embodiment of the present invention. When the light from the light source 4 is incident on the light guide plate 1 from the refraction part 9, the light is refracted by the angle of incidence on the refraction part 9 based on Snell's law. As shown in the drawing, the optical axis 11 is refracted with the refraction portion 9 as a boundary, and the angle formed by the incident angle and the output angle is changed.

FIG. 3 is a diagram showing Snell's law. Snell's law states that when light travels from one medium to another, the incident and refracted rays are on the normal plane, on the opposite side of the boundary, and the ratio of the sine of the two to the normal is The rule is that it is constant. Here, a certain medium A13
Is n1, and the refractive index of one medium B14 is n2.
Then, when light passes between certain substances, n1 × S
In (incident angle) = n2 × Sin (emission angle), the light is refracted or totally reflected. If the angle between the refraction portion 9 and the end face 3 of the light guide plate parallel to the light source 4 is 0 ° or more and less than 90 °, the end face 3 of the light guide plate parallel to the light source 4 is used.
Is refracted in a direction in which the angle between the angle and the angle is 90 ° or more. The refracted light is irregularly reflected by dots or linear patterns formed on the back surface of the light guide plate 1, and shines uniformly through the diffusion member 7. Further, by forming a shape similar to that described above on the side end surface of the light guide plate 1 and attaching and applying the light reflection / diffusion member 10 to the surface, light that leaks out of the light guide plate 1 is effectively used. be able to. In the figure, the boundary between the medium A13 and the medium B14 is indicated by the boundary surface 12. The optical axis enters from the medium A13 as an incident light ray, is refracted at the boundary surface 12 between the medium A13 and the medium B14, and is emitted as an outgoing light ray 16. Assuming that the angle between the incident light 11 and the normal 17 is the incident angle 15 and the angle between the output light and the normal 17 is the output angle 16, the optical axis shifts from the incident angle 15 to the output angle 16.

Next, another embodiment of the present invention will be described with reference to FIGS.

FIG. 4 is a schematic diagram showing another embodiment of the present invention. In this embodiment, when the shape of the refraction portion 9 is formed by a semicircular or elliptical curve and a straight line, the semicircular or elliptical curve on the end face 3 side of the light guide plate 1 is used. The angle between the tangent 18 drawn at the starting point and the straight line of the bending portion 9 is also assumed to be an obtuse angle.

FIG. 5 is a schematic diagram showing another embodiment of the present invention. In this embodiment, the light guide plate end face 3 of the refraction part 9 is used.
Is gradually reduced as it approaches the side end face of the light guide plate 1.

[0030]

According to the backlight device of the present invention, the light from the light source is refracted by the shape of the end face of the light guide unit.
Light is reflected by the shape of the end surface on the light guide unit side. Therefore, the light from the light source can be guided to the light guide unit near the electrode portion and the non-light emitting portion of the light source. As a result, there is an effect that it is easy to obtain a backlight device having no uniform unevenness.

Similarly, by reflecting light according to the shape of the end surface on the light guide unit side, it is possible to reduce the size of the display.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of an embodiment of the present invention.
(A) shows a front view and (b) shows a side view.

FIG. 2 is an enlarged view showing a light source side end face of the embodiment of the present invention.

FIG. 3 is a diagram showing Snell's law.

FIG. 4 is a schematic view showing another embodiment of the present invention.

FIG. 5 is a schematic view showing another embodiment of the present invention.

FIG. 6 is a schematic diagram showing a configuration of a conventional example. (A) shows a front view and (b) shows a side view.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light guide plate 2 Pattern 3 Light guide plate end surface 4 Light source 5 Socket 6 Reflector 7 Diffusion member 8 Reflection member 9 Refraction part 10 Reflection diffusion part 11 Optical axis 12 Boundary surface between mediums 13 Medium 1 14 Medium 2 15 Incident angle 16 Exit angle 17 Normal to the interface 18 tangent

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F21V 8/00

Claims (9)

(57) [Claims] A linear light source; a socket for holding the linear light source; a reflector for effectively reflecting light from the linear light source; a light guide plate for irregularly reflecting the light; and a rear surface of the light guide plate. And a sheet-like reflecting member for reflecting the light, and a sheet-like diffusing member for diffusing or condensing the light, wherein the linear light source has a shorter overall length than the light guide plate. An end face on the light source side of the light guide plate has a refraction portion for refracting light from the light source, and an end face near the light source of the light guide plate has a shape similar to the refraction portion. When the light source is incident on the light guide plate from the refraction unit, the light source is refracted by an incident angle to the refraction unit, and the reflection / diffusion unit causes the light source of the light guide plate to be in the vicinity of a non-light emitting unit. Brightness unevenness can be eliminated. Back lighting device and butterflies. 2. The refracting portion has a shape of a light emitting portion close to an electrode portion and a non-light emitting portion of the light source, and a shape such that light from the light source is refracted in the direction of the electrode portion and the non-light emitting portion. The backlight device according to claim 1, wherein: 3. The backlight unit according to claim 2, wherein the shape has a length equal to or less than a length from a side end surface of the light guide plate to a center end surface of the non-light emitting portion of the lamp. . 4. The backlighting device according to claim 2, wherein the refraction portion is formed in a plurality of substantially triangular shapes with respect to a longitudinal direction of the light source. 5. The backlighting device according to claim 4, wherein the substantially triangular shape is formed by a semicircular or elliptical curve and a straight line. 6. The light guide plate according to claim 5, wherein the angle between the tangent drawn at the start point of the semicircular or elliptic curved light guide plate at the end face side and the straight line of the refraction portion is an obtuse angle. A backlight device as described in the above. 7. The backlighting device according to claim 4, wherein an angle between an angle before the refraction of the light source and an angle after the refraction is an obtuse angle (90 ° or more). . 8. When the light from the light source enters the light guide plate from the refraction portion, the light is refracted at an angle of incidence on the refraction portion based on Snell's law. The backlight device according to any one of claims 7 to 10. 9. The light guide plate according to claim 4, wherein the depth of the refraction section from the end face of the light guide plate is reduced stepwise as it approaches the side end face of the light guide plate. Back lighting device.