JP2002072901A - Back light device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a back light device which permits highly brilliant illumination. SOLUTION: Dot-like light sources 14 are connected with a circuit board 15. A reflection member 16 is disposed in front of the circuit board 15, has opening parts 16a which are corresponding to the dot-like light sources 14 and reflects the light of the dot-like light sources 14. A prism sheet 22 has plural prism parts 22a and is disposed in front of the reflection member 26.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight device having a plurality of point light sources (e.g., light emitting diodes) disposed on a circuit board.

[0002]

2. Description of the Related Art Conventionally, there is a liquid crystal display device having a liquid crystal display device 1 as shown in FIG. 6 and a backlight device 2 for illuminating the liquid crystal display device 1. The liquid crystal display element 1 is a device in which polarizing plates (not shown) are attached to both sides of a liquid crystal cell in which liquid crystal is sealed in a pair of translucent substrates 3 provided with a transparent electrode film. A tape carrier package 4 (hereinafter referred to as TCP) is connected to the liquid crystal display element 1.
The TCP 4 has a flexible circuit board 5 on which a drive circuit 6 for driving the liquid crystal display element 1 is provided. A hard circuit board 7 is connected to the TCP 4, and a microcomputer 8 for controlling the drive circuit 6 is provided on the hard circuit board 7.

The liquid crystal display element 1 is a light receiving type display element which cannot emit light by itself, and is provided with a backlight device 2, which illuminates the liquid crystal display element 1 from behind by using the backlight device 2, thereby providing a good liquid crystal display device. Visibility is obtained. The backlight device 2 includes a hard circuit board 7
And a light emitting diode 9. The backlight device 2 includes a hard circuit board 7 having a through hole 7a formed therein.
After the terminal 9a of the light-emitting diode 9 is inserted, the wiring pattern formed on the rear surface of the hard circuit board 7 is connected to the terminal 9a with solder S.

[0004]

However, it cannot be said that the above-mentioned backlight device 2 always irradiates the light emitted from the light emitting diode 9 to the liquid crystal display element 1 efficiently. That is, the light emitted in the forward direction illuminates the liquid crystal display element 1, but the light emitted in the obliquely backward direction hits the circuit board 7 and does not contribute to the illumination of the liquid crystal display element 1. The present invention has been made in view of the above problem, and an object of the present invention is to provide a backlight device that can efficiently irradiate light emitted from a light source to a display element and perform high-luminance illumination.

[0005]

According to the present invention, a plurality of point light sources 14 and a plurality of point light sources 14 are provided.
Are connected to the circuit board 15, and openings 16a, 16b, which are arranged in front of the circuit board 15 and correspond to the point light sources 14, respectively.
And reflecting members 16 and 24 for reflecting the light of the point light source 14.

[0006] The present invention also provides a plurality of prism portions 22a.
The prism sheet 22 having
It is arranged in front of.

Further, according to the present invention, there is provided a case body 17 for accommodating the circuit board 15 and the reflection members 16 and 24, and the second surface for reflecting the light of the point light source 14 on the inner surface of the case body 17. A reflection member 23 is provided.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. 1 to 4 are diagrams showing a first embodiment. Reference numeral 11 denotes a liquid crystal display element. The liquid crystal display element 11 is a liquid crystal cell in which liquid crystal is sealed in a pair of translucent substrates 12, and polarizing plates (not shown) are attached to both front and rear surfaces of the liquid crystal cell. The liquid crystal display element 11 is of a so-called STN (super twisted nematic) type, and the liquid crystal display element 11 is a dot matrix type in which many pixels are arranged in a matrix.

Reference numeral 13 denotes a backlight device (light emitting device).
(Point light source), a hard circuit board 15 and a reflection plate 16 (reflection member). The reflection plate 16 has a reflection film adhered to the front surface of a resin substrate. As shown in FIG. 2, the reflector 16 has circular openings 16a corresponding to the eleven light emitting diodes 14, respectively. The diameter of the opening 16a is slightly larger than the diameter of the light emitting diode.

Reference numeral 17 denotes a case body.
The liquid crystal display element 11, the hard wiring board 15, and the reflection plate 16 are assembled. Reference numeral 18 denotes a TCP in which a driving circuit 20 is provided on a flexible wiring board 19. One end of the flexible wiring board 19 is connected to the liquid crystal display element 11 by an anisotropic conductive film (not shown), and the other end is connected to the hard circuit board 15. A predetermined wiring pattern is formed on the rear surface of the hard circuit board 15, and a microcomputer 21 for controlling the drive circuit 20 is provided.

Reference numeral 22 denotes a prism sheet. The prism sheet 22 is disposed between the reflection plate 16 and the liquid crystal display element 11 and is assembled to the case 17. Reference numeral 23 denotes a reflection film (a second reflection member). The reflection film 23 is attached to the inner surface of the side wall 17 a of the case body 17. The prism sheet 22 is made of, for example, a 3M brightness enhancement film (trade name: BEF). As shown in FIGS. 3 and 4, the prism sheet 22 has a large number of fine prism portions 22a,
2a is disposed on the liquid crystal display element 11 side, and the rear surface 22b is disposed on the light emitting diode 14 side.

The prism portion 22a has a substantially triangular prism shape, and the angle θ of the inclined surface 22c of the prism portion 22a is 45 ° with respect to the normal of the rear surface 22b. Although the prism portion 22a is shown in an enlarged manner, the ridge line 22d is shown.
Are as small as about 50 μm. The prism sheet 22 can improve the brightness of the backlight device 13 by refracting the light L obliquely incident on the rear surface 22b and collecting the light of the light emitting diodes 22 in the vertical direction. The light L ′ that has entered the rear surface 22b substantially perpendicularly.
Is reflected backward by the slope 22c.

According to this embodiment, the light emitting diode 14
The light emitted obliquely rearward from is reflected forward by the reflection plate 16, and this light can also contribute to the illumination of the liquid crystal display element 11, and high-luminance illumination becomes possible. Further, the light L ′ reflected backward by the slope 22 c of the prism sheet 22 is also reflected forward again by the reflector 16.
In addition, since the light hitting the side wall 17a of the case body 17 is also reflected by the reflection film 23, the illumination brightness is further improved.

Incidentally, as in the second embodiment shown in FIG.
The light emitting diode 14 may be supported by the reflecting plate 24, and the same effect as in the first embodiment can be obtained. In this case, the diameter of the opening 24a of the reflection plate 24 is smaller than the diameter of the light emitting diode 24. In addition, the point light source of the first and second embodiments is the light emitting diode 14, but may be a bulb, for example.

[0015]

The present invention has a plurality of point light sources, a circuit board to which the point light sources are connected, and openings disposed in front of the circuit board and corresponding to the point light sources, respectively. A reflecting member for reflecting the light of the point light source,
Since the light emitted obliquely rearward from the point light source is reflected forward by the reflection member, high-luminance illumination can be performed.

Further, according to the present invention, a case body for housing the circuit board and the reflection member is provided, and a second reflection member for reflecting light of the point light source is provided on an inner surface of the case body. In addition, illumination with higher luminance is possible.

[Brief description of the drawings]

FIG. 1 is a sectional view of a backlight device showing a first embodiment of the present invention.

FIG. 2 is a front view of a reflection member showing the embodiment.

FIG. 3 is a perspective view of a prism sheet showing the embodiment.

FIG. 4 is an enlarged sectional view of a main part of the prism sheet showing the embodiment.

FIG. 5 is a sectional view of a backlight device showing a second embodiment of the present invention.

FIG. 6 is a cross-sectional view of a backlight device showing a conventional example.

[Explanation of symbols]

 Reference Signs List 13 backlight device 14 light emitting diode (point light source) 15 circuit board 16 reflector (reflective member) 16a opening 17 case body 22 prism sheet 22a prism portion 23 reflective film (second reflective member) 24 reflector (reflective member) ) 24a opening

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // F21Y 101: 02 G02F 1/1335 530

Claims (3)

[Claims] 1. A point light source comprising: a plurality of point light sources; a circuit board to which the point light sources are connected; and an opening disposed in front of the circuit board and corresponding to each of the point light sources. And a reflecting member for reflecting the light. 2. The backlight device according to claim 1, wherein a prism sheet having a plurality of prism portions is disposed in front of the reflection member. 3. The backlight device according to claim 1, further comprising a case body for housing the circuit board and the reflection member, and reflecting the light of the point light source on an inner surface of the case body. A backlight device, comprising: a second reflecting member for causing the backlight device to emit light.