JP2003109421A - Back light unit and display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a back light unit capable of enhancing luminance with a comparatively simple structure and possible to be miniaturized and a display device. SOLUTION: This back light unit is provided with a light guide plate 1 having a light emitting surface 12 propagating light entered from light entrance surfaces 11a, 11b and emitting it, LED's 2, 2 provided on the light entrance surfaces 11a, 11b, and a display part 3 provided so as to be positioned on the light emitting surface 12 side of the light guide plate 1. Since the LED's 2, 2 provided on the light entrance surfaces 11a, 11b are positioned so that the entering directions of the light from them are different from each other, lowering light emitting efficiency of the LED 2 by heat from another LED 2 can be suppressed, and thereby luminance of the display part 3 can be enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight unit and a display device.

[0002]

2. Description of the Related Art For a backlight unit using a directional light source, particularly an LED, a sidelight system in which a display unit is illuminated by using a light guide means is often used. The sidelight method is a method of irradiating a display unit by allowing light to enter from an end surface of a light guide plate or other light guide means, propagating the incident light to one surface substantially orthogonal to the end surface, and emitting the light from this one surface. is there.

In response to such a tendency, for example, Japanese Patent Laid-Open No. Hei 11
The one described in Japanese Patent Publication No. 344705 is known. In this conventional technique, an extended portion is formed by extending the light incident surface of the light guide plate, which is the light guide means, in the vicinity of the LED provided on the substrate. As a result, the light from the LED can be effectively guided to the light guide plate from the lower surface of the extension portion and efficiently emitted.

[0004]

However, in the prior art, when the number of LEDs is increased in order to improve the brightness of the display section, the luminous efficiency of the LEDs is reduced due to the influence of heat from each other when the distance between adjacent LEDs is short. Because it will decrease
As a result, many LEDs must be arranged in the same direction, and the backlight unit may become large. Further, it is conceivable to increase the distance between the adjacent LEDs so as not to be affected by the heat of the adjacent LEDs, but this may also increase the size of the backlight unit. There is a problem that the display device provided cannot be downsized.

The present invention has been made in view of the above problems, and provides a backlight unit and a display device which can improve the brightness and can be miniaturized with a relatively simple structure. With the goal.

[0006]

A backlight unit according to a first aspect of the present invention includes a light guide means having a light incident surface and a light emitting surface through which the light incident from the light incident surface propagates and emits the light. A light source provided on the light incident surface; and a display section provided so as to be located on the light emitting surface side of the light guide means,
A plurality of light incident surfaces are provided on one side surface of the light emitting surface,
In addition, it is characterized in that the incident directions of light from the light sources provided on the respective light incident surfaces are different from each other.

In the present invention, the definitions and technical meanings of terms are as follows unless otherwise specified.

The light guiding means has a function as a planar light source that optically propagates the light incident from the light incident surface inside and emits the light from the light emitting surface. There is no particular limitation. For example, a light guiding method such as a hollow method in which the light guiding means is formed by the reflecting means and the transmitting portion is also allowed.

As a preferable light guide means, a light guide plate made of synthetic resin is used.

Further, the light guiding means may be provided with a reflecting means on the surface opposite to the light emitting surface. This reflection means
It can be formed by adhering a silver sheet or a white resin sheet having a high reflectance, or can be formed by applying a white pigment or the like to the light guide means. Further, a plate having a high reflectance, which is separate from the light guide unit, may be arranged. Furthermore, there is a prism cut shape or dot processing in which a plurality of unevenness is provided on the surface facing the light emitting surface, and a rough surface processing in which a surface facing the light emitting surface is polished to form fine unevenness, but the invention is not limited to these. Not something.

The light source preferably has directivity. The shape may be linear or dot-like.

The display unit may be any display means such as a light-transmissive flat display panel, and is provided with a display means for displaying characters, patterns, images or video when illuminated by light from a light source. Examples thereof include those in which a desired coating is printed on a translucent resin, glass or the like to form a display portion, or liquid crystal display means, but the material and structure are not particularly limited.

In the backlight unit of the first aspect, first, a plurality of light incident surfaces are provided on one side surface of the light emitting surface of the light guide means. Next, a light source is provided on each light incident surface, the light emitted from this light source is incident on the light guide means, and the incident light propagates inside the light guide means and is emitted from the light emission surface. The light source provided on the light incident surface is provided so that the incident direction of the light incident on the light guide means is different from that of the light source provided on the other light incident surface. Then, the light emitted from the light emitting surface illuminates the display unit.

According to the first aspect of the present invention, a light guide means having a light incident surface and a light emitting surface through which the light incident from the light incident surface propagates and emits the light; provided on the light incident surface. A light source; and a display unit provided so as to be positioned on the light emitting surface side of the light guide means; a plurality of light incident surfaces are provided on one side surface of the light emitting surface, and Since the incident directions of the light from the light sources provided on the incident surface are different from each other, it is possible to prevent the light sources from decreasing in luminous efficiency due to heat from other light sources.
The brightness of the display portion can be improved.

Further, since a plurality of light sources can be provided in directions other than the same direction, it is possible to prevent the backlight unit from becoming large.

A backlight unit according to a second aspect of the present invention is provided with a light guide surface having a light incident surface and a light emitting surface through which the light incident from the light incident surface propagates and emits the light; A point light source; and a display section provided so as to be positioned on the light emitting surface of the light guide means, and the light incident surface is provided on each of the plurality of light introducing sections protruding toward the side facing the light emitting surface. It is characterized by being.

According to another aspect of the backlight unit of the present invention, a point light source is first provided on each of the light entrance surfaces provided in the plurality of light introducing portions, and the light emitted from the point light source enters the light guide means. Then, the incident light propagates in the light guide means and is emitted from the light emitting surface to illuminate the display portion.

According to the second aspect of the present invention, a light guide means having a light incident surface and a light emitting surface through which the light incident from the light incident surface propagates and emits the light; provided on the light incident surface. A point light source; and a display section provided so as to be positioned on the light emitting surface of the light guide means, and the light incident surface is provided on each of the plurality of light introducing sections protruding toward the side facing the light emitting surface. Since it is possible to suppress the decrease in light emission efficiency due to heat from other point light sources compared to the structure in which the point light source is provided only on one light incident surface, The brightness of the part can be improved.

Since a plurality of point light sources can be provided not only in the same direction on one light incident surface but on different light incident surfaces, it is possible to prevent the backlight unit from becoming large.

According to a third aspect of the present invention, there is provided the backlight unit according to the first aspect, wherein the light guide means projects from one side of the light emitting surface provided with the light incident surface to the side opposite to the display section side. Is provided with two light entrance surfaces, one of which is substantially parallel to the light exit surface and the other of which is substantially orthogonal to the light exit surface. It is characterized by

The light introducing section may be provided integrally with the light guiding means or may be provided separately.

According to the invention of claim 3, in the light guide means, the light introducing portion is formed on one side surface of the light emitting surface on which the light incident surface is provided, the light introducing portion projecting to the side opposite to the display portion side. The light introducing portion is provided with two light incident surfaces, one of which is substantially parallel to the light emitting surface and the other of which is substantially orthogonal to the light emitting surface, thereby providing a plurality of light sources. It is possible to improve the brightness of the display unit without increasing the area for the use and prevent the backlight unit from becoming large.

A backlight unit according to a fourth aspect is the backlight unit according to the second aspect, wherein the light introducing portion of the light guiding means is provided such that the light incident surface is substantially orthogonal to the light emitting surface. Is characterized by.

According to the invention of claim 4, the light introducing portion of the light guiding means is provided such that the light incident surface is substantially orthogonal to the light emitting surface, so that the light source is guided when viewed from the display portion. Since it can be provided entirely within the outline of the light emitting surface of the light means,
It is possible to improve the brightness of the display unit without increasing the area when viewed from the display unit, and it is possible to prevent the backlight unit from becoming large.

According to a fifth aspect of the present invention, in the backlight unit according to any one of the first to fourth aspects, the light introducing portion has at least one of an inclined surface and a curved surface facing the light incident surface. It is characterized by being formed.

In the present invention, when the light guide means is a light guide plate made of synthetic resin, the inclined surface and the curved surface are formed on the surface other than the light incident surface so that the light can be transmitted from one side surface where the light incident surface is provided. Light incident on the area of the light guide means in which the light exit surface is formed can be more efficiently propagated in the light guide means, and the luminance uniformity of the light exit surface can be increased.

According to the fifth aspect of the present invention, the light introducing portion has at least one of the inclined surface and the curved surface facing the light incident surface. Most of the light is reflected by the inclined surface and the curved surface and efficiently enters the region of the light guide means where the light emitting surface is formed, so that the brightness uniformity of the light emitting surface can be increased.

A backlight unit according to a sixth aspect is the backlight unit according to any one of the first to fifth aspects, wherein the light sources provided on the respective light incident surfaces are mutually different from the light sources provided on the different light incident surfaces. It is characterized in that they are provided so as not to overlap or face each other.

According to the invention of claim 6, the light sources provided on the respective light incident surfaces are provided so as not to overlap with or oppose to the light sources provided on the different light incident surfaces. Therefore, it is possible to further prevent the light source from lowering its luminous efficiency due to heat from another light source.

The display device according to claim 7 is the display device according to claim 1 or 6.
A backlight unit according to any one of the above; and a device main body in which the backlight unit is provided and the lighting device is housed;

According to the invention of claim 7, it is possible to obtain a display device having the operation according to claim 1 or 6.

[0032]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing a display device according to a first embodiment of the present invention, FIG. 2 is an enlarged sectional view of an essential part showing a light guiding means and a light source, and FIG. 3 is a light guiding means and a light source. FIG. 6 is an enlarged side cross-sectional view showing the main part of FIG.

In each drawing, 1 is a light guide plate which is a light guide means, 2 is an LED which is a light source, 3 is a display unit, 10 is a backlight unit, and 20 is a display device.

The light guide plate 1 is made of a transparent acrylic resin and is provided with the light incident surfaces 11a and 11b and the light incident surface 11.
It has a light emitting surface 12 through which the light incident from a and 11b propagates and the light is emitted.

The light incident surfaces 11a and 11b are the light emitting surfaces 12
Are provided on one side surface side 12a of each of the light incident surfaces 11a, 11b so that the incident directions of light from the LEDs 2, 2, ...

"One side 12a of the light emitting surface 12"
Means that the LED 2 is used so as to directly illuminate the display unit 3 described later.
The LED 2 is provided so that the light is incident on the light guide plate 1 from any side direction of the light emitting surface 12 instead of being provided directly below the display unit 3. The lateral direction incident on the light plate 1 may be only one lateral direction, or may be provided so that light may be incident from a plurality of lateral directions.

Further, the light guide plate 1 has a light introducing portion 1 projecting from one side surface side 12a of the light emitting surface 12 to the side opposite to the display portion 3 side.
3 is formed, and the light emitting surface 12 is formed on the light introducing portion 13.
A light incident surface 11a that is substantially parallel to and a light incident surface 11b that is substantially orthogonal to the light emitting surface 12 are provided.

Further, the light guide plate 1 has the light incident surfaces 11a and 11b.
On the side surface 12a where the
An inclined surface 14 and a curved surface 15 are formed at locations other than 1a and 11b. Furthermore, the inclined surface 14 and the curved surface 15
A reflecting plate 6 made of a high-reflecting material is provided along the line.

When the light guide plate 1 is formed in this way, as shown in FIG. 3, the light incident on the light guide plate 1 from the light incident surface 11a is reflected by the inclined surface 14 to the curved surface 15 and reaches the curved surface 15. The light is reflected so as to enter the region of the light guide plate 1 where the light exit surface 12 is formed, that is, the region of the light guide plate 1 where the display unit 3 is provided. When the light reaching the inclined surface 14 is totally reflected in the light introducing portion 13, the inclined surface 1
It is not necessary to provide the reflection plate 6 along the line 4.

Furthermore, the surface of the light guide plate 1 facing the light emitting surface 12 is provided with a prism cut having a plurality of irregularities so that the luminance uniformity of the display unit 3 can be further improved. Has been formed.

The LED 2 is connected to the lighting device 4 by the wiring 21, and the respective light incident surfaces 11a and 11 are connected.
A plurality of them are provided in b. At this time, as shown in FIG. 2, the LED 2 provided on the light incident surface 11a is provided so as not to overlap the LED 2 provided on the different light incident surface 11b.

The LED 2 may be provided so as to be mounted on a circuit board, or the board may be formed so as to be a part of the lighting device.

The display portion 3 is formed of a translucent milky white acrylic resin in a flat plate shape, and a display pattern (not shown) of an arrow indicating the evacuation direction is printed on the outer surface side by a green translucent paint. There is.

The apparatus main body 5 is made of a synthetic resin having a high reflectance, an opening (not shown) has a rectangular shape, and the display portion 3 is provided in the opening.

In the present embodiment, first, the light incident surfaces 11a, 1
Power is supplied from the lighting device 4 to the LEDs 2, 2, ... Provided in 1b, and light is incident on the light introducing section 13 from the LEDs 2, 2 ,.

When the light incident on the light introducing portion 13 from the LED 2 provided on the light incident surface 11a reaches the inclined surface 14 as shown by the arrow in FIG. 3, it is reflected by the inclined surface 14 or the reflecting plate 6 to the curved surface 15. To do. The light reaching the curved surface 15 is reflected so as to enter the region of the light guide plate 1 where the display unit 3 is provided, propagates in the light guide plate 1 and is emitted from the light emitting surface 12.

When most of the light that has entered the light introducing section 13 from the LED 2 provided on the light incident surface 11b reaches the curved surface 15 as shown by the arrow in FIG. 3, the light guide plate 1 provided with the display section 3 is shown. The light is reflected so as to be incident on the area, propagates in the light guide plate 1, and is emitted from the light emitting surface 12.

According to this embodiment, the light incident surfaces 11a, 1
The light guide plate 1 having a light emitting surface 12 through which the light incident from 1b propagates and emits the light, the LEDs 2, 2 provided on the light incident surfaces 11a and 11b, and the light emitting surface 12 side of the light guide plate 1 are provided. The light incident surface 11a, 11b is provided on one side surface side 12a of the light emitting surface 12 and the LED 2 provided on the light incident surface 11a, 11b. Since the incident directions of light from 2 ...
Since it is possible to prevent the luminous efficiency from decreasing due to heat from the EDs 2, 2, ..., It is possible to improve the brightness of the display unit 3.

Further, since a plurality of LEDs 2, 2, ... Can be provided in a direction other than the same direction, the backlight unit 10 can be provided.
And the display device 20 can be prevented from becoming large.

Further, since the light guide plate 1 is provided with the light introducing portion 13, the brightness of the display portion 3 can be improved without enlarging the area for providing the plurality of LEDs 2, 2 ,. Moreover, it is possible to prevent the backlight unit 10 and the display device 20 from becoming large.

Further, the light guide plate 1 includes the inclined surface 14 and the curved surface 1.
5 is formed and the reflection plate 6 is provided, most of the light from the LEDs 2, 2 ...
Since the light is incident on the region of the light guide plate 1 in which the light guide plate 2 is formed, the luminance uniformity of the light emitting surface 12 can be further increased.

Further, the LEDs 2, 2, ... Provided on the light incident surfaces 11a, 11b are provided so as not to overlap with the LEDs provided on the different light incident surfaces 11a, 11b, so that the LED 2 is different. It is possible to further suppress a decrease in luminous efficiency due to heat from the LED 2.

Next, a second embodiment will be described with reference to the drawings.

FIG. 4 is an enlarged side cross-sectional view of an essential part showing the light guide means and the point light source of the second embodiment. The same components as those in the first embodiment are designated by the same reference numerals, and their description will be omitted. Omit it. The second embodiment is different from the first embodiment in the structure of the light guide plate on the one side surface on which the light incident surface is provided.

The light guide plate 1a is made of a transparent acrylic resin as in the first embodiment. In addition, the light incident surfaces 11a and 11
On one side surface side 12a where b is provided, an inclined surface 14a and an inclined surface 14b are formed at positions other than the light incident surfaces 11a and 11b. When formed in this way, as shown in FIG. 4, the light incident on the light guide plate 1a from the light incident surface 11a is reflected by the inclined surface 14a to the inclined surface 14b, and the light reaching the inclined surface 14b is reflected by the light emitting surface 12. The light efficiently enters the formed area of the light guide plate 1a. In addition, the light incident surface 1
Light that has entered the light guide plate 1a from 1b is reflected by the inclined surface 14b and efficiently enters the region of the light guide plate 1a where the light exit surface 12 is formed.

According to this embodiment, most of the light from the LEDs 2, 2, ... Is provided on the light guide plate 1a on which the light emitting surface 12 is formed.
Since the light is incident on the area, it is possible to easily increase the brightness uniformity and brightness of the light exit surface 12.

Next, a third embodiment will be described with reference to the drawings.

FIG. 5 is a side sectional view showing an essential part of this embodiment, and FIG. 6 is an enlarged bottom view of an essential part showing a light guide means and a point light source, which are the same as those of the first and second embodiments. The same reference numerals are given to the configurations, and the description thereof will be omitted. In addition, in FIG. 6, illustration of the prism cut and the reflector 6a are omitted.

The light guide plate 1c is made of a transparent acrylic resin as in the first and second embodiments, and the light exit surface 12 through which the light incident from the light entrance surfaces 11c and 11d propagates and exits.
b and 12b.

Further, the light guide plate 1 has the light emitting surfaces 12b and 12b.
The light introducing portions 13a and 13b are formed so as to project toward the side opposite to the light emitting surface 12b and 12b of the light introducing portions 13a and 13b.
c and 11d are provided respectively.

Further, the light introducing portion 13a is formed with inclined surfaces 14c and 14d, and the light introducing portion 13b is formed with inclined surfaces 14e and 14f. When formed in this way, as shown in FIG. 5, the light incident surfaces 11c and 11d are formed.
The light that has entered the light guide plate 1a from is reflected by the inclined surfaces 14c and 14e to the inclined surfaces 14d and 14f, and the inclined surfaces 14d and 14f.
The light that has reached is efficiently incident on the region of the light guide plate 1c in which the light emitting surfaces 12b and 12b are formed.

Further, the light guide plate 1c is formed with an intermediate portion 16 so as to connect the light introducing portion 13a and the light introducing portion 13b, and the side of the intermediate portion 16 facing the light emitting surfaces 12b, 12b is highly reflected. A reflector 6a made of a member is provided. By providing this reflecting plate 6a, the light emitting surface 12
Light is also emitted from the intermediate portion 16 between b and 12b.

As shown in FIG. 6, the LEDs 2, 2 ... Are provided so that the LED 2 provided on the light incident surface 11c and the LED 2 provided on the light incident surface 11d do not face each other.

According to the present embodiment, the LED 2 provided on the light incident surface 11c and the LED 2 provided on the light incident surface 11d have substantially the same effect as the first embodiment, and are provided so as not to face each other. Therefore, it is possible to further prevent the LED 2 from lowering the luminous efficiency due to heat from the other LEDs 2.

Further, when viewed from the display section 3, the LEDs 2, 2 ...
Is provided entirely inside the light emitting surfaces 12b, 12b of the light guide plate 1c.
It is possible to improve the appearance of the apparatus main body provided with.

Further, since the plurality of LEDs 2 are provided only in the substantially central portion of the light guide plate 1c without being dispersed, the structure of the wiring 21 to the LEDs 2 can be simplified. It is very effective that the wiring structure of the light source such as the LED 2 can be simplified in this way because the work of replacing the light source can be facilitated.

[0068]

According to the first aspect of the present invention, a light guide means having a light incident surface and a light emitting surface through which the light incident from the light incident surface propagates and emits the light; A light source provided; a display unit provided so as to be located on the light emitting surface side of the light guide means; and a plurality of light incident surfaces are provided on one side surface of the light emitting surface, each of which is provided. Since the light incident surfaces of the light sources are provided so that the light incident directions thereof are different from each other, it is possible to prevent the light sources from decreasing in luminous efficiency due to heat from other light sources. The brightness of can be improved.

Further, since a plurality of light sources can be provided in directions other than the same direction, it is possible to prevent the backlight unit from becoming large.

According to the second aspect of the present invention, a light guide means having a light incident surface and a light emitting surface through which the light incident from the light incident surface propagates and emits the light; provided on the light incident surface. A point light source; and a display section provided so as to be positioned on the light emitting surface of the light guide means, and the light incident surface is provided on each of the plurality of light introducing sections protruding toward the side facing the light emitting surface. Since it is possible to suppress the decrease in light emission efficiency due to heat from other point light sources compared to the structure in which the point light source is provided only on one light incident surface, The brightness of the part can be improved.

Since a plurality of point light sources can be provided not only in the same direction on one light incident surface but on different light incident surfaces, it is possible to prevent the backlight unit from becoming large.

According to the invention of claim 3, in the light guide means, the light introducing portion is formed on one side of the light emitting surface on which the light incident surface is provided, the light introducing portion projecting to the side opposite to the display portion side. The light introducing portion is provided with two light incident surfaces, one of which is substantially parallel to the light emitting surface and the other of which is substantially orthogonal to the light emitting surface, thereby providing a plurality of light sources. It is possible to improve the brightness of the display unit without increasing the area for the use and prevent the backlight unit from becoming large.

According to the invention of claim 4, the light introducing portion of the light guiding means is provided so that the light incident surface is substantially orthogonal to the light emitting surface, so that the light source is guided when viewed from the display portion. Since it can be provided entirely within the outline of the light emitting surface of the light means,
It is possible to improve the brightness of the display unit without increasing the area when viewed from the display unit, and it is possible to prevent the backlight unit from becoming large.

According to the fifth aspect of the present invention, since the light introducing portion is formed with at least one of the inclined surface and the curved surface facing the light incident surface, the light incident from the point light source Most of the light is reflected by the inclined surface and the curved surface and efficiently enters the region of the light guide means where the light emitting surface is formed, so that the brightness uniformity of the light emitting surface can be increased.

According to the invention of claim 6, the light sources provided on the respective light incident surfaces are provided so as not to overlap with or oppose the light sources provided on the different light incident surfaces. Therefore, it is possible to further prevent the light source from lowering its luminous efficiency due to heat from another light source.

According to the invention of claim 7, it is possible to obtain a display device having the effect of any one of claims 1 and 5.

[Brief description of drawings]

FIG. 1 is a sectional view showing a display device according to a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view of an essential part showing a light guide means and a light source.

FIG. 3 is an enlarged side sectional view of an essential part showing the light guide means and the light source.

FIG. 4 is an enlarged side sectional view of an essential part showing a light guide unit and a light source according to a second embodiment of the present invention.

FIG. 5 is an enlarged side sectional view showing an essential part of a third embodiment of the present invention.

FIG. 6 is an enlarged bottom view of an essential part showing a light guide unit and a light source according to a third embodiment of the present invention.

[Explanation of symbols]

1, 1a, 1c ... Light guide plate as light guide means 11a, 11b, 11c, 11d ... Light incident surface 12, 12a ... Light emitting surface 2 ... LED as a light source 3 ... Display 10, 10 '... Backlight unit

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) // F21Y 101: 02 F21Y 101: 02

Claims (7)

[Claims] 1. A light guide means having a light entrance surface and a light exit surface through which the light entered from the light entrance surface propagates and emits light; a light source provided on the light entrance surface; A display unit provided so as to be located on the light emitting surface side;
A plurality of light incident surfaces are provided on one side surface of the light emitting surface,
Further, the backlight unit is provided such that the incident directions of light from the light sources provided on the respective light incident surfaces are different from each other. 2. Light guiding means having a light incident surface and a light emitting surface through which light incident from the light incident surface propagates and emits light; a point light source provided on the light incident surface; A display portion provided so as to be located on the light emitting surface of the means, and the light incident surface is provided on each of a plurality of light introducing portions protruding toward the side facing the light emitting surface. Backlight unit to do. 3. The light guide means has a light introducing portion formed on one side of a light emitting surface provided with a light incident surface, the light introducing portion projecting to the side opposite to the display portion side. 2. The backlight unit according to claim 1, wherein two light incident surfaces are provided so that is substantially parallel to the light emitting surface and the other is substantially orthogonal to the light emitting surface. 4. The backlight unit according to claim 2, wherein the light introducing portion of the light guiding means is provided such that the light incident surface is substantially orthogonal to the light emitting surface. 5. The backlight unit according to claim 1, wherein the light introducing portion is formed with at least one of an inclined surface and a curved surface at a position facing the light incident surface. . 6. A light source provided on each light incident surface is provided so as not to overlap with or oppose to a light source provided on a different light incident surface. 5. The backlight unit according to any one of 5. 7. A display device comprising: the backlight unit according to claim 1; and a device body provided with the backlight unit and containing a lighting device.