JP2012042526A - Liquid crystal backlight device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a direct-type backlight device with reduced luminance unevenness.SOLUTION: There is provided a direct-type backlight liquid crystal device which reflects light from a plurality of light sources in the direction of a liquid crystal display panel, and which is arranged behind the light sources in order to illuminate the liquid crystal display panel. The direct-type backlight liquid crystal device includes a plurality of light sources arranged on a print circuit board at predetermined intervals, a lamp house arranged on the print circuit board to surround the light sources and having a side surface outwardly oblique from the bottom to the top, an optical sheet provided to seal an opening at an upper part of the lamp house, and a liquid crystal panel arranged on the optical sheet. A plurality of protrusions each in the shape of a triangular pyramid widening from the bottom to the top are provided on a side of the lamp house.

Description

  The present invention relates to a liquid crystal backlight device, and more particularly to a liquid crystal backlight device in which luminance unevenness of a direct type backlight device is improved.

  Since the liquid crystal of the liquid crystal display device cannot be displayed without light, a backlight is used for displaying in a dark place. As the light source of the backlight, a cold cathode tendency discharge tube, a flat fluorescent lamp, an electroluminescence plate, an LED, and the like are used. The LED is advantageous for downsizing.

  3A to 3C are perspective views showing a configuration of a liquid crystal backlight device using an LED as a light source, FIG. 3B is a cross-sectional view taken along the line AA in FIG. 3A, and FIG. It is a figure which shows the state of light and dark when the light from LED is irradiated to the made character.

  In these drawings, 1 is a printed circuit board, and 2 is an LED arranged in a straight line on the printed circuit board at a predetermined distance, and emits light when power is supplied from a power source (not shown). Reference numeral 3 denotes a rectangular lamp house which is arranged on a printed circuit board and surrounds a plurality of LEDs 2. The lamp house 3 is fixed so that the LED 2 is located near the center of the long side.

  A side wall 3a inclined outward is formed from the bottom of the four sides of the lamp house 3, and an optical sheet 4 formed in accordance with the size of the area formed by the top is fixed to the top of the side wall 3a. The liquid crystal panel 5 is fixed on the upper surface.

  In the configuration described above, the light emitted from the LED 2 is visually recognized through the optical sheet 4 and the liquid crystal panel 5. Some of the visible light is reflected by the side surface 3 a of the lamp house 3 or the printed circuit board 1 and reaches the light.

  That is, all of the light emitted from the LED 2 does not directly pass through the optical sheet 4 and the liquid crystal panel 5, but a part of the light is reflected by these surfaces and returned to the LED 2 side. Reflect to the side.

JP 2001-281656 A JP 2001-305535 A JP 2008-034273 A

By the way, such a conventional liquid crystal backlight device has a problem in that the brightness of characters displayed on the liquid crystal varies.
FIG. 3C shows a state in which the light from the LED 2 varies when viewed from the viewpoint S. The LED 2 is located at the portions indicated by black circles B1, B2, and B3, and C1 and C2 indicated by dotted lines. , C3 portion is bright, and other portions such as D1, D2, and D3 are dark.

  The present invention has been made to solve the above-described problems, and aims to improve luminance unevenness of a direct type backlight device.

In order to achieve such a problem, the backlight device of the present invention is as follows.
In a direct-type backlight liquid crystal device that is arranged behind a plurality of light sources to illuminate a liquid crystal display panel and reflects light from the light sources to the liquid crystal display panel side,
A plurality of light sources disposed on the printed circuit board at a predetermined interval; and a plurality of light sources disposed on the printed circuit board so as to surround the plurality of light sources, the side surfaces thereof being inclined outward from the bottom. A plurality of lamp houses, an optical sheet provided by closing an upper opening of the lamp house, and a liquid crystal panel disposed on the optical sheet, and extending from the bottom to the side of the lamp house A plurality of triangular pyramid-shaped protrusions are provided.

In claim 2, in the backlight liquid crystal device according to claim 1,
The plurality of triangular pyramid-shaped protrusions are arranged to face each other with the light source interposed therebetween.

In claim 3, in the backlight liquid crystal device according to claim 1 or 2,
The light source is an LED.

  According to the first to third aspects of the present invention, a lamp house which is disposed so as to surround a plurality of LED light sources and whose side surfaces are inclined outward from the bottom portion, and an opening portion at the top of the lamp house And a liquid crystal panel disposed on the optical sheet, and provided with a plurality of triangular pyramid-shaped protrusions extending upward from the bottom on the side surface of the lamp house, Since they are arranged facing each other across the light source, by distributing a part of the light that goes to the part close to the light source, the brightness of the display part away from the light source is improved and the entire unevenness is eliminated, and the brightness is uniform. Can be realized.

The principal part block diagram (a) which shows an example of embodiment of the backlight apparatus of this invention, AA sectional drawing (b) of a figure, The light from LED was irradiated to the character displayed on the liquid crystal It is a figure (c) which shows the contrast of time. It is a principal part block diagram which shows another Example. Main part block diagram (a) which shows a prior art example, AA sectional drawing (b) of figure (a), The figure which shows the light and dark when the light from LED is irradiated to the character displayed on the liquid crystal (c) It is.

  FIG. 1 is a main part configuration diagram (a) showing an example of an embodiment of a backlight device of the present invention, AA sectional view (b) of FIG. 1 (a), light from an LED on a character displayed on a liquid crystal It is a figure (c) which shows the light and dark when irradiated.

  In these drawings, 1 is a printed circuit board, and 2 is an LED arranged in a straight line on the printed circuit board at a predetermined distance, and emits light when power is supplied from a power source (not shown). Reference numeral 3 denotes a rectangular lamp house which is arranged on the printed circuit board and surrounds the plurality of LEDs 2. The lamp house 3 is fixed to the surface of the printed circuit board 1 so that the LED 2 is located near the center of the long side. ing.

  A side wall 3a inclined outward is formed from the bottom of the four sides of the lamp house 3, and an optical sheet 4 formed in accordance with the size of the area formed by the top is fixed to the top of the side wall 3a. The liquid crystal panel 5 is fixed on the upper surface.

  Reference numeral 7 denotes a plurality of triangular pyramid-shaped protrusions formed on the inclined side wall 3a of the lamp house 3, and has a shape spreading upward from the bottom. The projection 7 may be formed by processing the side wall 3a of the lamp house 3 by sheet metal working, or a triangular plate may be fixed to the flat side wall by welding or bonding.

  As shown in FIG. 1B, a plurality of triangular pyramid-shaped protrusions are formed to face each other with the LED 2 interposed therebetween. Therefore, the light emitted from the LEDs 2 in an oblique direction is reflected by the surface of the triangular pyramid and is distributed to the area of the liquid crystal panel far from each LED.

As a result, the portion close to the originally bright LED 2 is slightly darkened, but the portion far from the conventionally dark LED is brightened, thereby reducing the difference in brightness and improving the unevenness of brightness.
FIG. 2 shows another embodiment, in which a projection having a shape different from that in FIG. 1 is formed on the side wall 3a of the lamp house 3. In FIG.

  In FIG. 2, reference numeral 7a denotes a triangular prism-shaped protrusion corresponding to the side wall width (h) from the bottom of the lamp house 3 to the top of the side wall, and 7b denotes a relatively large diameter corresponding to the side wall width (h). 7c is provided with a plurality of small hemispherical small protrusions, for example, a dozen or so.

FIG. 2 shows a state in which the protrusions are formed only on one side of the side wall, but the protrusions are formed on both side surfaces facing the LED 2. Even in the above-described configuration, the light emitted from the LEDs 2 in the oblique direction is reflected by the surface of the protrusion and is distributed to the regions of the liquid crystal panel 5 far from the respective LEDs 2.
2 shows three types of projections on the side wall 3a, these projections may be provided in a single type, or a plurality of types may be provided in a mixed state. .

  The above description merely shows a specific preferred embodiment for the purpose of explanation and illustration of the present invention. The shape of the protrusion may be the same as that of the convex mirror, and may be a shape in which light emitted from the LED spreads to a distant portion.

Further, an optical reflective film or the like may be applied to the projections functioning as the reflecting means, the side wall of the lamp house, and the surface of the printed board.
Therefore, the present invention is not limited to the above-described embodiments, and includes many changes and modifications without departing from the essence thereof.

1 Printed circuit board 2 LED
3 Lamp house 3a Side wall 4 Optical sheet 5 Liquid crystal panel 6 Triangular pyramidal projection 7a Triangular columnar projection 7b Hemispherical large projection 7c Hemispherical small projection

Claims (3)

  In a direct-type backlight liquid crystal device that is arranged behind a plurality of light sources to illuminate a liquid crystal display panel and reflects light from the light sources to the liquid crystal display panel side, the liquid crystal display panel is arranged on a printed circuit board at a predetermined interval. A plurality of light sources, a lamp house disposed on the printed circuit board so as to surround the plurality of light sources and having a side surface inclined outward from the bottom, and an opening at the top of the lamp house And a liquid crystal panel disposed on the optical sheet, and a plurality of triangular pyramid-shaped projections extending from the bottom toward the upper side are provided on the side surface of the lamp house. A backlight liquid crystal device.   The backlight liquid crystal device according to claim 1, wherein the plurality of triangular pyramid-shaped protrusions are arranged to face each other with the light source interposed therebetween.   The backlight liquid crystal device according to claim 1, wherein the light source is an LED.

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