JP2005129409A - Backlight apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a backlight apparatus capable of illuminating at a uniform brightness over the whole area of a light irradiating surface of a display. <P>SOLUTION: In the backlight apparatus in relation to the present invention comprising a reflection surface 41 opposite to a back side of a display 3, and an LED 21 disposed on one side of the reflection surface 41 for radiating a light toward the reflection surface, the reflection surface 41 has an inclined plane area approaching the back side of the display in proportion to the distance from the LED 21, an uneven surface of which cross section parallel with the direction of light radiation of the LED 21 and perpendicular to the back side of the display has triangle tooth like shape is formed in the reflection surface area and the spacing between a projection and a recess of the uneven surface gets smaller in proportion to the distance from the LED 21. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a backlight device that illuminates a light receiving display such as a liquid crystal display.

In a display device including a liquid crystal display, a backlight for illuminating the liquid crystal display is necessary, and various backlights have been proposed for uniformly illuminating the liquid crystal display.
Here, since the LED widely used as the light source is expensive, the light source is configured by as few LEDs as possible.

For example, a light source is arranged only on one side of the back surface (light irradiation surface) of the liquid crystal display, and the light emitted from the light source is diffusely reflected by the wave-like reflection surface and guided toward the back side of the liquid crystal display, and the liquid crystal There has been proposed a backlight device that diffuses the irregularly reflected light by a diffusion sheet disposed on the back side of the display and irradiates the back of the liquid crystal display (Patent Document 1).
JP-A-8-161918

However, in the above-described backlight device in which the light source is provided only on one side of the light irradiation surface, the light from the light source spreads over the entire area of the light irradiation surface due to irregular reflection and diffusion. There is a problem that the area far from the light source is darker than the area near the light source.
Therefore, an object of the present invention is to provide a backlight device that can illuminate the entire light irradiation surface of a display with a brightness that is more uniform than in the past.

  A backlight device according to the present invention includes a reflective surface that should face the back surface of a light-receiving display, and a light source that is disposed on one side of the reflective surface and emits light toward the reflective surface. The surface has a slope region that approaches the back surface of the display as it moves away from the light source, and the slope region has a triangular tooth shape that is parallel to the light emission direction of the light source and orthogonal to the back surface of the display. An uneven surface is formed, and the pitch of the uneven surface of the uneven surface decreases as the distance from the light source increases.

In the backlight device of the present invention described above, the light emitted from the light source is reflected by the reflecting surface and irradiated on the back surface of the display.
Here, since the distance from the light source to the back surface of the display becomes shorter as the distance from the light source increases, the length of the light path that is reflected at a position close to the light source and reaches the back surface of the display is reflected at a position far from the light source. Thus, the difference from the length of the optical path reaching the back of the display is reduced.

In addition, the triangular toothed uneven surface formed in the inclined area of the reflecting surface becomes smaller as the uneven pitch is further away from the light source, so that the light reflected at a position closer to the light source has a relatively large diffusivity. While the light travels toward the back of the display at (expansion angle), the light reflected at a position far from the light source travels toward the back of the display with a relatively small diffusivity (expansion angle). The region far from the light source is irradiated with light having a higher degree of convergence than the region near the light source.
As a result, the entire rear surface of the display is illuminated with a more uniform brightness than before.

  Specifically, the slope region is formed by an arc surface. As a result, discontinuous changes in the amount of light applied to the back surface of the display can be avoided, and the brightness of illumination on the back surface of the display can be made more uniform.

More specifically, a frame member (48) having an opening (40) formed toward the back surface of the display is provided, and the reflection surface is formed on the bottom surface of the opening (40) of the frame member (48). The light source is attached to one end of the frame member (48).
The frame member (48) is provided with a rib (42) for restricting light traveling from the light source to a region near the light source.
This limits the amount of light that travels from the back of the display to an area closer to the light source and avoids the area being illuminated too brightly.

The frame member (48) is provided with one or a plurality of holes (43) (44) for allowing light from the light source to escape to the back side of the frame member (48) at a position close to the light source. .
This limits the amount of light that travels from the back of the display towards the area closer to the light source and avoids the area being illuminated too brightly.

In a more specific configuration, the frame member (48) is formed with a receiving part (46) for installing the light source and a pressing piece (52) for pressing the light source against the receiving part (46). The prepared lid member (5) is fixed.
As a result, the light source is reliably held in a predetermined posture with the optical axis facing the reflecting surface.

  According to the backlight device of the present invention, it is possible to illuminate the entire light irradiation surface of the display with a more uniform brightness than in the past by using a light source provided only on one side.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention implemented in a backlight device for a liquid crystal display will be specifically described below with reference to the drawings.
The backlight device according to the present invention is installed in an audio device having a display window (12) on the front panel (11) of the cabinet (1) as shown in FIG. On the circuit board (6), a display device (2) for displaying characters and the like in the display window (12) is installed.
The display device (2) is a combination of a horizontally long liquid crystal display (3) and a rectangular parallelepiped backlight (4) for illuminating the liquid crystal display (3). A single LED (21) serving as a light source is incorporated at one end in the direction.

As shown in FIG. 3, the backlight (4) has a rectangular parallelepiped frame member (48) formed by integrally molding a white synthetic resin, and the frame member (48) faces the liquid crystal display (3). An opening (40) that opens is recessed.
In the opening (40) of the frame member (48), an accommodation part (49) for the LED (21) is formed at one end in the longitudinal direction, and light emitted from the LED (21) is liquid crystal. A reflection surface (41) for reflecting toward the display (3) is formed.
The liquid crystal display (3) is attached to the frame member (48) so as to face the reflecting surface (41), and the lid member (5) is fixed so as to cover the LED housing portion (49).

Further, a rib (42) for narrowing the light from the LED (21) protrudes toward the liquid crystal display (3) at a position near the LED (21) in the opening (40) of the frame member (48). In addition, holes (43) and (44) for allowing the light from the LED (21) to escape to the back side of the frame member (48) are opened before and after the rib (42) (see FIG. 4). ).
Further, a pair of hooks (45) and (45) to be engaged with a pair of engaging portions (51) and (51) protruding from the lid member (5) are provided on the side wall of the frame member (48). Has been.
In addition, a pressing piece (52) for pressing the LED (21) against the LED accommodating portion (49) is projected from the lid member (5).

As shown in FIG. 4, the reflection surface (41) of the frame member (48) has an arc surface area that approaches the back surface of the liquid crystal display (3) as it moves away from the LED (21). A concave-convex surface having a triangular tooth shape is formed in a cross-section that is parallel to the light emission direction of the LED (21) and orthogonal to the back surface of the liquid crystal display (3). It gets smaller as you move away from 21).
Further, a flat portion (47) having no irregularities is formed in a region near the LED (21) in the reflecting surface (41).

  The LED (21) is sandwiched between a receiving portion (46) projecting upward from the frame member (48) and a pressing piece (52) projecting downward from the lid member (5), and the light The two legs (22) extending horizontally from the LED (21) are bent in an L shape, and the tip ends of the circuit board (6). It penetrates.

As indicated by a chain line in FIG. 4, the light emitted from the LED (21) is first irradiated and reflected on the reflection surface (41), and then proceeds toward the back surface of the liquid crystal display (3). Illuminate.
Here, since the distance from the LED (21) to the back surface of the liquid crystal display (3) becomes shorter as the reflecting surface (41) moves away from the LED (21), it is reflected at a position closer to the LED (21) and reaches the back surface of the display. The difference between the length of the optical path and the length of the optical path reflected at a position far from the LED (21) and reaching the back of the display is reduced.

  In addition, the triangular toothed uneven surface formed on the reflective surface (41) is smaller as the uneven pitch is further away from the LED (21), so the light reflected at a position closer to the LED (21). While the light travels toward the back of the display with a relatively large diffusivity (expansion angle), the light reflected far from the LED (21) travels toward the back of the display with a relatively small diffusivity (expansion angle). The region far from the LED (21) in the rear surface of the display is irradiated with light having a higher degree of convergence than the region near the LED (21).

  In addition, the light emitted from the LED (21) toward the region near the reflecting surface (41) is restricted by the rib (42), the amount of light is limited, and as shown by the chain line in the figure, the hole is (43) Passing through (44) and escaping to the back side of the frame member (48), so that the light near the LED (21) in the back side of the liquid crystal display (3) is irradiated. The amount will be reduced and it will be avoided that the area is illuminated too brightly.

  As a result, it is possible to illuminate the entire back surface of the liquid crystal display (3) with a more uniform brightness than in the past by a single LED (21) provided only at one end of the frame member (48).

  In addition, each part structure of this invention is not restricted to the said embodiment, A various deformation | transformation is possible within the technical scope as described in a claim. For example, the reflection surface (41) of the frame member (48) is not limited to an arcuate surface, and may be formed on a polygonal surface. Further, the pitch of the unevenness of the reflecting surface (41) can be changed continuously or changed stepwise. Further, it is also effective to form the reflecting surface (41) on the uneven surface and to form the uneven surface with a rough surface finer than the uneven pitch.

It is a perspective view which shows the external appearance of the audio equipment which should be equipped with the backlight apparatus which concerns on this invention. 1 is a perspective view of a display device including a backlight device according to the present invention. It is a disassembled perspective view of this display apparatus. It is an expanded sectional view of the display device.

Explanation of symbols

(2) Display device
(21) LED
(3) Liquid crystal display
(4) Backlight
(40) Opening
(41) Reflective surface
(42) Ribs
(43) Hole
(44) Hole
(48) Frame member
(49) LED housing
(5) Lid member
(52) Pressing piece

Claims (7)

  In a backlight device that irradiates light on the back surface of a light receiving display, a reflective surface that should face the back surface of the display, and a light source that is disposed on one side of the reflective surface and emits light toward the reflective surface; The reflective surface has a slope region that approaches the back surface of the display as it is moved away from the light source, and the slope region has a cross-sectional shape that is parallel to the light emission direction of the light source and orthogonal to the back surface of the display. Has a triangular tooth-shaped uneven surface, and the uneven pitch of the uneven surface decreases as the distance from the light source increases.   The backlight device according to claim 1, wherein the slope region is formed by an arc surface.   3. The backlight device according to claim 1, wherein a region near the light source in the reflecting surface is formed as a flat surface.   A frame member (48) having an opening (40) formed toward the back surface of the display is provided, and the reflection surface is formed on the bottom surface of the opening (40) of the frame member (48), and the frame member (48 The backlight device according to any one of claims 1 to 3, wherein the light source is attached to one end of the light source.   5. The backlight device according to claim 4, wherein a rib (42) is provided on the frame member (48) so as to project light that travels to a region near the light source in the reflecting surface.   The frame member (48) is provided with one or a plurality of holes (43) (44) for allowing light from the light source to escape to the back side of the frame member (48) at a position close to the light source. Or the backlight apparatus of Claim 5. The frame member (48) is formed with a receiving portion (46) for installing the light source, and a lid member (5) having a pressing piece (52) for pressing the light source against the receiving portion (46). The backlight device according to claim 4, wherein the backlight device is fixed.

Images