JP2004265709A - Backlight device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a backlight device easily adapting to variation in specification at low cost. <P>SOLUTION: A liquid crystal display device (20) is installed in close contact with a top surface of a diffuser sheet (10), and stick-type light sources (30) are installed below the diffuser sheet. A plurality of trough shaped reflectors (40) provided with a U-shaped reflecting surfaces facing the stick type light source are installed corresponding to each stick-type light source, on the lower side of the stick-type light source and the upper side of the substracte. Each trough-like reflecting source is individually formed and they are fixed to the substrate by bolts (3). A section or a parabola is formed orthogonal to a longitudinal axis of each trough shape reflecting board. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a backlight device for irradiating a liquid crystal display device or the like with light from the back.
[0002]
[Prior art]
A backlight device is used to irradiate a liquid crystal display device or the like with light from the back. Among them, a liquid crystal display device is provided on one surface side of a planar diffusion plate as a device used for a liquid crystal television or the like, and light is radiated from the other surface side of the diffusion plate through the diffusion plate. There is a direct type backlight device.
For example, there is an apparatus disclosed in Japanese Patent Application Laid-Open No. 2002-116704. In this device, a plurality of rod-shaped light sources are arranged on the other surface side of the diffusion plate, and a flat reflecting plate is further arranged on the side farther from the diffusion plate than the light source.
[0003]
Patent Document 2 (Japanese Patent Application Laid-Open No. 2002-372933) discloses that a gutter-shaped reflector having a gutter-shaped reflector instead of a flat plate can be used to irradiate an illuminated object such as a liquid crystal display device with stronger light. Is disclosed. However, the gutter-shaped reflecting plate is integrally formed into a corrugated plate. Therefore, if the arrangement of the light sources is different, a light source corresponding to the different light sources must be newly redesigned, and there is a problem that it is costly to respond to a change in specifications.
[0004]
[Patent Document 1]
JP 2002-116704 A [Patent Document 2]
JP-A-2002-372933 [0005]
[Problems to be solved by the invention]
The present invention has been made in view of the above problems, and has as its object to provide a backlight device that can easily cope with specification changes at low cost.
[0006]
[Means for Solving the Problems]
According to the first aspect of the present invention, light emitted from a light source provided on the other surface side of the diffusion plate is applied to an irradiation target provided on one surface side of the planar diffusion plate, A backlight device for irradiating through a diffusion plate,
The light source is a plurality of rod-shaped light sources arranged substantially parallel to the diffusion plate,
A reflection plate that can reflect light emitted from the rod-shaped light source toward the diffusion plate is disposed on the anti-diffusion plate side of the rod-shaped light source,
The reflector is a plurality of trough-shaped reflectors having a longitudinal axis extending in parallel to the longitudinal axis of the rod-shaped light source, with the concave surface facing the rod-shaped light source, for each of the rod-shaped light sources. In addition, there is provided a backlight device characterized in that the plurality of gutter-shaped reflectors are formed independently of each other and supported independently of each other.
In the backlight device configured as described above, on the anti-diffusion plate side of a plurality of rod-shaped light sources arranged substantially parallel to the diffusion plate, the concave surface of each of the rod-shaped light sources is directed toward the rod-shaped light source, A plurality of gutter-like reflectors having a longitudinal axis extending parallel to the axis are provided, and the plurality of gutter-like reflectors are formed independently and supported independently.
[0007]
According to a second aspect of the present invention, there is provided the backlight device according to the first aspect, wherein a cross section of the reflecting surface of the gutter-shaped reflecting plate perpendicular to the longitudinal axis direction is a parabola. .
[0008]
According to a third aspect of the present invention, in the second aspect of the present invention, the rod-shaped light source is disposed at a focus position of the parabola, and the gutter-shaped reflector is located at a vertex of the parabola. The distance between the focal point and the vertex is fixed to Ld, and a line perpendicular to a straight line passing through the focal point and the vertex is fixed to a substrate parallel to the diffuser disposed on the side opposite to the light source. Where Lh = 2 × Ld, where Lh is the distance between the point of intersection with the focal point, and a backlight device.
[0009]
According to a fourth aspect of the present invention, in the first aspect of the present invention, the plurality of gutter-shaped reflectors are arranged such that two adjacent edges extending in the longitudinal axis direction are in contact with each other. An apparatus is provided.
[0010]
According to a fifth aspect of the present invention, there is provided the backlight device according to the fourth aspect of the present invention, wherein a supporting column for supporting the diffusion plate is attached to a portion where the edge contacts. .
[0011]
According to the invention of claim 6, in the invention of claim 5, a projection is formed at the same position in the longitudinal direction on each of the adjacent edges that are in contact with each other, and the projection is provided at least on the reflection plate side of the support. The backlight device has a hole in which the backlight device can be fitted.
[0012]
According to a seventh aspect of the present invention, there is provided the backlight device according to the fifth aspect, wherein the support is formed in a hollow cylindrical shape.
[0013]
According to an eighth aspect of the present invention, there is provided the backlight device according to the fifth aspect, wherein the support is formed of a transparent material.
[0014]
According to a ninth aspect of the present invention, there is provided the backlight device according to the first aspect, wherein the object to be irradiated is a liquid crystal display device.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of a backlight device according to the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a cross-sectional view illustrating a backlight device according to the present invention. Reference numerals 1a and 1b denote side walls of a housing, and reference numeral 2 denotes a substrate of the housing. Has a depth in the front and back directions.
The diffusion plate 10 is supported and arranged by the side walls 1 a and 1 b of the housing and the side wall of the housing (not shown) at the front and back ends of the drawing. The liquid crystal display device 20 is disposed with the intermediary of the liquid crystal display device 11.
[0016]
A plurality of rod-shaped light sources 30 extend with a longitudinal axis in the front and back directions of the drawing, are supported by side walls of a casing (not shown) at the ends in the front and back directions of the drawing, and are disposed below the diffusion plate 10 in the drawing. ing. In this embodiment, the rod-shaped light source 30 has a round rod shape with a diameter of about 3 mm.
On the lower side of the rod-shaped light source 30 in the drawing and on the upper side of the substrate 2 in the drawing, a plurality of gutter-shaped reflectors 40 having a concave reflecting surface facing the rod-shaped light source 30 are arranged corresponding to each rod-shaped light source 30. Each gutter-shaped reflecting plate 40 has a longitudinal axis extending in parallel with the longitudinal axis of the rod-shaped light source 30, that is, in the front-back direction of the drawing. The gutter-shaped reflection plate 40 is formed of, for example, an aluminum plate.
[0017]
Each gutter-like reflector 40 is formed separately, and they are respectively fixed to the substrate 2 by the bolts 3. Here, being formed separately does not mean that the shapes are different from each other. For example, it means that it is made using the same mold, but is not a continuous plate like a corrugated plate. Therefore, when the arrangement of the bar-shaped light sources 30 is changed due to the specification change, it can be dealt with by changing the mounting position of each gutter-like reflector 40 in accordance with the change, and the specification change is easy and the cost is not increased.
[0018]
FIG. 2 is a view for explaining the positional relationship between the surface 41 of the gutter-shaped reflector 40 and the rod-shaped light source 30. The surface 41 draws a parabola when viewed from the front and back of the drawing. The rod-shaped light source 30 is arranged so that there is a center of 30. The vertex P of the parabola is located directly below in the figure, that is, the gutter-shaped reflecting plate 40 is fixed to the substrate 2 with the bolt 3 at the position of the vertex P.
[0019]
Then, assuming that a point at which a line segment perpendicular to a straight line passing through F and P intersects the surface 41 is Q, the length of the line segment FP is Ld, and the length of the line segment FQ is Lh, Lh = It is set to 2 × Ld. In this embodiment, Ld is set to about 3.5 to 4.5 mm.
The width between the two edges of each gutter-shaped reflector 40 is determined according to the pitch of the rod-shaped light sources 30, and is about 15 to 35 mm. The depth is determined according to the width. For example, when the width is 25 mm, the depth is about 11 mm.
[0020]
FIG. 3 shows a state in which light emitted from the rod-shaped light source 30 is reflected on the surface 41 of the gutter-shaped reflector 40 formed as described above. As shown in FIG. All of the light reflected at 41 enters the diffuser 10 perpendicularly. As a result, the liquid crystal display device 20 can be irradiated with strong light.
[0021]
Further, as shown in FIG. 1, a column 50 for supporting the diffusion plate 10 is disposed at an edge of the adjacent gutter-shaped reflection plate 40 that abuts on each other. As shown in the figure, the struts 50 are not provided at the edges of all the adjacent gutter-shaped reflectors 40 that are in contact with each other, but are appropriately thinned out to have an optimum number. In addition, an appropriate number of them are provided at appropriate intervals in the front and back directions of the drawing.
[0022]
FIG. 4 is a partially exploded assembly view for explaining the mounting of the above-mentioned support column 50 on the gutter-shaped reflector 40. First, minute projections 43 are formed at the same positions on a part of the edges 42 that abut each other on the adjacent gutter-shaped reflection plates 40. On the other hand, the support column 50 is formed in a cylindrical shape, and two small projections 43 formed in the hole 51 at a part of the end edges 42 of the adjacent gutter-shaped reflection plates 40 which abut each other. Is inserted. In this embodiment, the width in the longitudinal direction of each projection 43 is 2 mm, and the thickness (= reflection plate thickness) is 0.5 mm. Correspondingly, the pillar has an inner diameter of about 2 mm and an outer diameter of about 3 mm. Degree.
Note that the columns 50 are formed of a transparent resin such as acrylic or polycarbonate, so that the light applied to the liquid crystal display device 20 does not become uneven.
[0023]
【The invention's effect】
The invention described in each claim is to irradiate an object disposed on one surface side of a planar diffusion plate, light emitted from a light source disposed on the other surface side of the diffusion plate, It is a backlight device that irradiates through a diffusion plate, the light source is a plurality of rod-shaped light sources arranged substantially parallel to the diffusion plate, the light emitted from the rod-shaped light source on the anti-diffusion plate side of the rod-shaped light source A reflection plate that can reflect toward the diffusion plate is provided, and the reflection plate is disposed with the concave surface facing the rod-shaped light source side for each of the rod-shaped light sources, and is disposed on a longitudinal axis of the rod-shaped light source. A plurality of gutter-shaped reflectors having a longitudinal axis extending in parallel, wherein the plurality of gutter-shaped reflectors are formed independently and supported independently.
Therefore, even if the arrangement of the light sources is changed due to the specification change, it is only necessary to change the attachment of the gutter-shaped reflectors accordingly, and it is possible to easily cope with the specification change at low cost.
[0024]
Particularly, as in the invention of claim 5, two adjacent edges of the plurality of gutter-shaped reflectors extending in the longitudinal axis direction are in contact with each other, and the diffusion plate is supported at a portion where the edges are in contact. If the support is attached, the diffusion plate can be supported without interfering with the reflection surface of the reflection plate. Furthermore, if the support is formed of a transparent material as in the invention of claim 8, uniformity of irradiation light is not hindered.
[Brief description of the drawings]
FIG. 1 is a sectional view of a backlight device according to the present invention.
FIG. 2 is a diagram illustrating a shape of a reflecting surface of a gutter-like reflecting plate of the backlight device of FIG.
FIG. 3 is a diagram for explaining light reflection by a gutter-shaped reflector.
FIG. 4 is a partially exploded assembly view for explaining attachment of a support supporting a diffusion plate to a gutter-like reflection plate.
[Explanation of symbols]
1a, 1b Side wall (of housing) 2 Board (of housing) 3 Screw 10 Diffusion plate 11 Diffusion sheet 20 Liquid crystal display 30 Rod light source 40 Gutter-like reflector 41 Reflector 42 Edge 43 (of the gutter-shaped reflector) Projection 50 Prop 51 Hole

Claims (9)

A backlight device that irradiates light emitted from a light source disposed on the other surface side of the diffusion plate to an irradiation target disposed on one surface side of the planar diffusion plate through the diffusion plate. So,
The light source is a plurality of rod-shaped light sources arranged substantially parallel to the diffusion plate,
A reflection plate that can reflect light emitted from the rod-shaped light source toward the diffusion plate is disposed on the anti-diffusion plate side of the rod-shaped light source,
The reflector is a plurality of trough-shaped reflectors having a longitudinal axis extending in parallel to the longitudinal axis of the rod-shaped light source, with the concave surface facing the rod-shaped light source, for each of the rod-shaped light sources. A backlight device characterized in that the plurality of gutter-shaped reflectors are formed independently and supported independently. The backlight device according to claim 1, wherein a cross section of the reflecting surface of the gutter-shaped reflecting plate perpendicular to the longitudinal axis direction is a parabola. The rod-shaped light source is disposed at a focus position of the parabola, and the gutter-shaped reflector at a vertex of the parabola is disposed on a substrate parallel to the diffusion plate disposed on a side opposite to the light source of the gutter-shaped reflector. Fixed, the distance between the focal point and the vertex was Ld, and the distance between the point at which the line passing through the focal point and a line perpendicular to the straight line passing through the focal point and the vertex intersected the parabola and the focal point was Lh. 3. The backlight device according to claim 2, wherein Lh = 2 × Ld. 2. The backlight device according to claim 1, wherein two adjacent edges of the plurality of trough-shaped reflectors extending in the longitudinal axis direction are in contact with each other. 3. 5. The backlight device according to claim 4, wherein a column supporting the diffusion plate is attached to a portion where the edge contacts. A projection is formed at the same position in the longitudinal direction on each of the adjacent edges that are in contact with each other, and a hole in which the projection can be fitted is provided at least on the reflection plate side of the support. 6. The backlight device according to 5. The backlight device according to claim 5, wherein the support is formed in a hollow cylindrical shape. The backlight device according to claim 5, wherein the pillar is formed of a transparent material. The backlight device according to claim 1, wherein the irradiation target is a liquid crystal display device.

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