JP2006156231A - Backlight - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a backlight having a simple structure, capable of making light having sufficient luminous energy reach to a distance of a hollow region and of improving uniformity of luminance. <P>SOLUTION: A light source part 20 is composed by providing it with LEDs 10, collimation lenses 15, and fly eye lenses 16 composed by arranging flat lenses 16b. By using the LEDs 10 as light sources, emission of light in an unnecessary diffusion direction is suppressed and light emitted from the light sources can efficiently be converted to parallel light by the collimation lenses 15. By converting the light efficiently converted to the parallel light to flat oblong luminous flux by the respective lens parts 16b of the fly eye lenses 16, much of the light from the light source part 20 can be made to directly reach to the distance of the hollow region 35 without reflecting it on a reflecting sheet 30 or the like. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a hollow type backlight.

  Conventionally, as a backlight system used for a liquid crystal television or the like, a hollow system in which light from a light source is emitted to a hollow region, reflected by a reflection sheet, and emitted from a light diffusion sheet is known. By the way, in general, this type of backlight has a problem in that it is easy to generate luminance unevenness although it can be reduced in weight as compared with a type having a light guide plate.

Therefore, for example, in Patent Document 1, light emitted from a discharge tube such as a cold cathode tube lamp as a light source is collected at a position away from the light source by a long convex lens body and is in contact with an air layer (hollow region). A technique is disclosed in which an irregular reflection layer (reflective sheet) is inclined upward as it moves away from a light source.
JP-A-8-171806

  However, since the light source such as the discharge tube is a cylindrical light source that emits light radially from the entire circumference, even if a convex lens body is provided between the light source and the hollow region, as in the technique disclosed in Patent Document 1 described above. Even if it is provided, the light that can be collected by the convex lens is limited. Therefore, with the above-described technique, it is difficult to allow a sufficient amount of light to reach far away from the hollow region, and it is difficult to obtain sufficient brightness uniformity even if the reflecting sheet is inclined.

  To cope with this, it is conceivable that a plurality of lenses are further interposed between the discharge tube and the convex lens body. However, when a plurality of lenses are used in this way, the backlight becomes large and the structure is complicated. There is a risk of inducing a change.

  An object of the present invention is to provide a backlight capable of reaching a sufficient amount of light far from a hollow region with a simple configuration and improving the uniformity of luminance.

  The present invention relates to a light source unit including a light emitting diode, a fly-eye lens in which a plurality of lens units that convert light emitted from the light emitting diode into flat rectangular light beams are arranged in a matrix, and the light source unit. A reflection means having end portions connected to each other, and a light emitting means for forming a hollow region between the reflection means and emitting light incident on the hollow region from each lens portion of the fly-eye lens. Features.

  According to the backlight of the present invention, with a simple configuration, a sufficient amount of light can reach far away from the hollow region, and the luminance uniformity can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 and 2 relate to the first embodiment of the present invention, FIG. 1 is an exploded perspective view of the backlight, FIG. 2 is a cross-sectional view of the backlight, and FIG. 3 shows the light flux formed by each lens portion of the fly-eye lens. It is explanatory drawing shown.

  1 and 2, reference numeral 1 denotes a backlight suitable for a liquid crystal television or the like. The backlight 1 has a flat, substantially box-shaped case 2 having an upper surface opened. The case 2 is made of, for example, a resin molded product by injection molding, and a partition wall 3 stands on the inner side of the back plate 2a. The partition wall 3 defines an LED storage chamber 5 and a light guide chamber 6 inside the case 2.

  The LED accommodating chamber 5 accommodates a plurality of (for example, three) surface-mounted light emitting diodes (hereinafter referred to as LEDs) 10 as light sources. Specifically, a pair of substrate holding grooves 5a facing each other are recessed at both longitudinal ends of the LED storage chamber 5, and these substrate holding grooves 5a are LED substrates on which the LEDs 10 are mounted at equal intervals. 11 is held in the LED storage chamber 5.

  As shown in FIGS. 1 and 2, each LED 10 housed and held in the LED housing chamber 5 has a collimation lens 15 and a fly-eye lens 16 (described later) held in the partition 3 corresponding to the LED 10. The light source unit 20 is formed on one side of the case 2.

  More specifically, the partition 3 has a communication groove 7 that communicates the LED storage chamber 5 and the light guide chamber 6 at each position corresponding to each LED 10. Furthermore, each communication groove 7 has a collimation lens holding groove 7a and a fly-eye lens holding groove 7b in order from the LED storage chamber 5 side on the wall surfaces facing each other.

  The collimation lens 15 is a lens member in which a lens portion 15b is integrally formed on the emission side of a substantially rectangular planar lens substrate 15a inserted and held in the collimation lens holding groove 7a. The collimation lens 15 converts the light incident from the LED 10 into substantially parallel light and emits it.

  The fly-eye lens 16 is a lens member in which a plurality of lens portions 16b having a planar rectangular shape are integrally formed in a matrix on a substantially rectangular planar lens substrate 16a inserted and held in the fly-eye lens holding groove 7b. . Here, as shown in FIGS. 1 and 3, each lens portion 16 b is set such that the dimension in the width direction (direction along the back plate 2 a) is larger than the dimension in the height direction (thickness direction of the case 2). It is a wide-angle lens part. Specifically, each lens part 16b preferably has a width-to-height dimension ratio of 2: 1 or more. In this embodiment, the cell dimension of each lens part 16b is, for example, 1.8 mm. X is set to 0.6 mm. And by such a shape, each lens part 16b converts the emitted light from LED10 converted into the substantially parallel light by the collimation lens 15 into the light beam of a rectangular flat in the width direction, and enters the light guide chamber 6. Exit. At this time, as shown in FIG. 3, most of the light beams emitted from the respective lens portions 16b are superimposed on each other, so that the fly-eye lens 16 is flat and uniform in the width direction as a whole. A luminous flux of illuminance is emitted into the light guide chamber 6.

  The light guide chamber 6 accommodates a reflection sheet 30 as a reflection means. Specifically, the reflection sheet 30 is formed of a rectangular sheet disposed along the back plate 2a, and the light source unit 20 is connected to an edge portion on one side thereof. As shown in FIG. 1, the reflection sheet 30 has a mirror surface 30 a formed by sticking a highly reflective film, for example, at a position close to the light source unit 20, and diffusely reflects, for example, at a position far from the light source unit 20. It has a diffusion surface 30b formed by sticking a sheet. The term “mirror surface” as used herein means that the reflection surface is not necessarily a specular reflection surface but may be a reflection surface that is close to a specular reflection. Similarly, a “diffuse surface” is also a reflection that is at least close to diffuse reflection. It means that the surface is enough. In the present embodiment, the boundary between the mirror surface 30a and the diffusing surface 30b is linear, and the area ratio is, for example, 3: 4. Further, in the light guide chamber 6, each side plate 2 b and the partition wall 3 of the case 2 are each provided with a white coating surface 31 that reflects the same light as that incident on the diffusion surface 30 b.

  A diffusion plate 33 facing the reflection sheet 30 is disposed at the opening end of the light guide chamber 6, and the diffusion plate 33 is connected to the reflection sheet 30 in the light guide chamber 6. A hollow region 35 is formed therebetween. The diffusing plate 33 is a light emitting means for emitting light incident on the hollow region 35 from the light source unit 20 with diffusion. In addition, a prism sheet 34 is attached to the light exit surface of the diffuser plate 33 (that is, the side opposite to the hollow region 35) to collect the light emitted from the diffuser plate 33 in the front direction and increase the front luminance. .

  Reference numeral 36 in the figure denotes a bezel that is provided on the case 2. The bezel 36 has an opening 36a corresponding to the light emitting surface of the prism sheet 34, and as shown in FIG. Further, the edge portions of the diffusion plate 33 and the prism sheet 34 are sandwiched between the case 2 and the edge portion.

  As shown in FIG. 2, in such a backlight 1, the light incident on the hollow region 35 from the light source unit 20 enters the mirror surface 30 a or the diffusion surface 30 b of the reflection sheet 30. The light incident on the mirror surface 30a is reflected at an angle of reflection that is substantially the same as the incident angle, and therefore is incident on the diffuser plate 33 further away from the position where the light is incident. Further, since the light incident on the diffusing surface 30b is diffused in various directions, the light is incident on the diffusing plate 33 near the position where the light is relatively incident. Accordingly, the amount of light emitted from the diffusion plate 33 can be reduced at a position close to the light source unit 20, and the amount of light emitted far away can be increased, improving the uniformity.

  According to such an embodiment, by using the LED 10 that is a point light source as a light source, it is possible to suppress the diffusion of light in an unnecessary direction, and the collimation lens 15 efficiently emits light emitted from the light source. Can be converted to Then, by converting the light that has been efficiently converted into parallel light into a flat rectangular light beam by each lens unit 16b of the fly-eye lens 16, a large amount of light emitted from the light source unit 20 can be obtained with a simple configuration. Without being reflected by the reflection sheet 30 or the like, it is possible to reach the far region of the hollow region 35 directly.

  Accordingly, the amount of light emitted from the diffusion plate 33 at a position far from the light source unit 20 can be increased, and the uniformity of the backlight 1 can be improved.

  Furthermore, by setting the reflection sheet 30 near the light source unit 20 as the mirror surface 30a and distant position as the diffusion surface 30b, a lot of light can be efficiently moved far away from the light source unit 20 even for the light reflected by the reflection sheet 30. Can lead.

  Next, FIGS. 4 and 5 relate to the second embodiment of the present invention, FIG. 4 is a cross-sectional view of a backlight, and FIG. 5 is an enlarged cross-sectional view showing reflection in the vicinity of a light source portion of a reflection sheet. In the present embodiment, the same components as those in the first embodiment described above are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 4, the second embodiment is different from the first embodiment in that a diffusion sheet 37 as a diffuse transmission means is further disposed on a mirror surface 30a made of a highly reflective film. This is the point.

  As shown in FIG. 5, when light is incident on the reflection sheet 30 at a position close to the light source unit, the incident light is diffusely transmitted by the diffusion sheet 37 after being specularly reflected by the mirror surface 30a. This diffuse transmission is not necessarily diffused in various directions as in the case of entering the diffusion surface 30 b, but substantially depends on the angle at which the light is emitted from the diffusion sheet 37. That is, since the direction of the light after reflection can be diffused while being controlled to some extent, the light can be reflected far away as in the first embodiment.

  In each of the above-described embodiments, an example in which the surface-mounted LED 10 is used as the light source of the light source unit 20 has been described. However, the present invention is not limited to this, and for example, the lens unit is a light emitting unit. A so-called bullet-type LED provided integrally may be used as the light source of the light source unit. In this case, in particular, since the directivity angle of the light emitted from the LED can be reduced, the light source unit can be configured by omitting the collimation lens.

  In addition, the number of LEDs 10 and the like used for the light source unit 20 is not limited to the above-described one, and may be changed as appropriate according to the size of the backlight.

  In particular, in the large-sized backlight 1, in order to further improve the uniformity, a diffusion surface is locally provided on the mirror surface 30a of the reflection sheet 30, or a mirror surface is locally provided on the diffusion surface 30b. Tuning is also possible.

1 is an exploded perspective view of a backlight according to the first embodiment of the present invention. Same as above, sectional view of backlight Explanatory drawing which shows the light beam which each lens part of a fly eye lens forms Sectional drawing of a backlight according to the second embodiment of the present invention Same as above, enlarged sectional view showing reflection in the vicinity of the light source part of the reflection sheet

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Back light, 10 ... Light emitting diode, 16 ... Fly eye lens, 16b ... Lens part, 20 ... Light source part, 30 ... Reflection sheet (reflection means), 30a ... Mirror surface, 30b ... Diffusing surface, 33 ... Diffusing plate (light emission) Means), 35 ... hollow region, 37 ... diffusion sheet (diffusion transmission means)
Agent Patent Attorney Susumu Ito

Claims (3)

A light source unit including a light-emitting diode and a fly-eye lens in which a plurality of lens units that convert light emitted from the light-emitting diode into flat rectangular light beams are arranged in a matrix;
Reflection means having an edge connected to the light source;
A light emitting means for forming a hollow area between the reflecting means and emitting light incident on the hollow area from each lens portion of the fly-eye lens;
Backlight characterized by comprising.   2. The backlight according to claim 1, wherein the reflecting means has a mirror surface at a position close to the light source unit and a diffusing surface at a far position.   3. The backlight according to claim 2, wherein a diffusion transmission means for diffusing and transmitting light is provided on the mirror surface of the reflection means.

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