JP2008076441A - Liquid crystal panel illuminator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a direct liquid crystal panel illuminator capable of suppressing luminance unevenness of a liquid crystal panel. <P>SOLUTION: Both ends of a cold cathode tube 3 are respectively supported by lamp holders 4 and a center part of the cold cathode tube is supported by a lamp post 5. The cold cathode tube 3 is maintained in a warped state so that the both ends are made nearer to the liquid crystal panel 1 than the center part by support by the lamp holders 4 and the lamp post 5. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a liquid crystal panel illumination device that is incorporated in a liquid crystal display device and illuminates a liquid crystal panel from the back side.

  2. Description of the Related Art Liquid crystal display devices such as televisions and large monitors incorporate a liquid crystal panel illumination device generally called a backlight that illuminates a liquid crystal panel serving as a display screen from the back. As the liquid crystal panel lighting device here, a so-called direct type is adopted.

  In a conventional general direct type liquid crystal panel lighting device, as shown in FIGS. 5 to 7, a plurality of cold cathode tubes 103 as light sources are parallel to each other inside a case 102 covering the back side of the liquid crystal panel 101. (See, for example, Patent Documents 1 and 2). Both ends of the cold cathode tube 103 are supported by lamp holders 104 fixed to the case 102, and further, the lamp holders 104 are supported by lamp posts 105 fixed to the case 102 at two locations, for example. The cold-cathode tube 103 here is a long and thin tube and is bent to some extent. However, the cold-cathode tube 103 is supported by the lamp holder 104 and the lamp post 105 so that the bending is suppressed. (See FIG. 6).

  Further, a reflection plate 108 is overlaid on the inner surface of the case 102, and a diffusion plate 109 is overlaid on the back surface of the liquid crystal panel 101 (see FIGS. 6 and 7).

In the cold cathode tube 103, for example, argon gas and an appropriate amount of mercury are sealed in the tube, a phosphor is applied to the inner wall, and terminals connected to the internal electrodes are provided on both end surfaces. Yes. A power supply line is electrically connected to each terminal. When a high voltage is applied through the terminal to the electrode in the cold cathode tube 103 from the power supply line, a discharge occurs in the cold cathode tube 103 and ultraviolet rays are emitted, thereby exciting the phosphor and emitting visible light. . The visible light reaches the diffusion plate 109 directly or through reflection by the reflection plate 108, diffuses through the diffusion plate 109, and illuminates the entire liquid crystal panel 101 from the back.
JP 2004-318176 A JP 2002-333842 A

  Strictly speaking, the cold cathode tube 103 is characterized by the fact that the luminance at both ends thereof is lower than that of the other portions, so that the cold cathode tube 103 is liquid crystal from end to end as in the conventional liquid crystal panel lighting device described above. When the panel 101 is held at a certain distance, the illuminance with respect to the liquid crystal panel 101 is lower at the portions corresponding to both ends of the cold cathode tube 103 than at the other portions. Then, in the liquid crystal panel 101, portions corresponding to the portions immediately above both ends of the cold cathode tube 103 are locally darkened, resulting in uneven brightness.

  Accordingly, the present invention has been made in view of the above problems, and an object of the present invention is to provide a direct-type liquid crystal panel illumination device capable of suppressing the occurrence of luminance unevenness in a liquid crystal panel.

  To achieve the above object, a liquid crystal panel lighting device according to the present invention comprises a plurality of cold cathode tubes arranged side by side on the back side of a liquid crystal panel, lamp holders that respectively support both ends of these cold cathode tubes, A liquid crystal panel illumination device comprising: a lamp post that supports the cold cathode tube between the lamp holders. The cold-cathode tube is supported at the center by the lamp post and is held in a bent state by the support by the lamp holder and the lamp post so that both ends are closer to the liquid crystal panel than the center. ing.

  With such a configuration, even if the brightness of the cold cathode tube is low at both ends, the both ends are held in a manner closer to the liquid crystal panel than the center, so the illuminance on the liquid crystal panel Is substantially uniform from end to end in the direction along the cold cathode tube. Accordingly, the liquid crystal panel has uniform brightness over the entire area.

  In addition, a liquid crystal panel lighting device according to the present invention for achieving the above object includes a plurality of cold cathode tubes arranged side by side on the back side of the liquid crystal panel, and lamp holders that respectively support both ends of these cold cathode tubes. And a lamp post that supports the cold cathode tube between the lamp holders, wherein the cold cathode tube is supported by the lamp holder and the lamp post so that both end portions are central portions. It is held in a bent state so as to be closer to the liquid crystal panel.

  Even with such a configuration, even if the brightness of the cold-cathode tube is low at both ends, the brightness of the liquid crystal panel is maintained because both ends are held closer to the liquid crystal panel than the center. Is substantially uniform from end to end in the direction along the cold cathode tube. Accordingly, the liquid crystal panel has uniform brightness over the entire area.

  Here, practically, it is preferable that the lamp post supports the central portion of the cold cathode tube.

  According to the liquid crystal panel illumination device of the present invention, the brightness is uniform over the entire area of the liquid crystal panel, and the occurrence of uneven brightness in the liquid crystal panel is suppressed.

  Hereinafter, a liquid crystal panel lighting device according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a plan view of a liquid crystal panel illuminating device according to an embodiment of the present invention, FIG. 2 is a sectional view taken along line AA, and FIG. 3 is a sectional view taken along line BB. 2 and 3, the liquid crystal panel and the diffusion plate, which are components of the liquid crystal display device, are also shown for convenience of explanation.

  In the liquid crystal panel illumination device of the present embodiment, as shown in FIGS. 1 to 3, a plurality of cold cathode tubes 3 as light sources are arranged in parallel to each other inside a case 2 that covers the back side of the liquid crystal panel 1. ing. The cold-cathode tube 3 is supported at both ends by lamp holders 4 fixed to the case 2, and further at the center by a lamp post 5 fixed to the case 2 one by one. The cold-cathode tube 3 here is an elongated tubular tube having a diameter of about 3 mm and is bent to some extent. By the support by the lamp holder 4 and the lamp post 5, both end portions are closer to the liquid crystal panel 1 than the center portion. (See FIG. 2).

  Specifically, the lamp holder 4 is positioned on the case 2 after the projection 4a is inserted into a through hole (not shown) formed in the case 2 after the end of the cold cathode tube 3 is fitted. The lamp frame 7 is covered with a spacer 6 interposed therebetween. When the lamp frame 7 and the case 2 are fastened with screws or the like, the lamp holder 4 is fixed on the case 2 while supporting the end of the cold cathode tube 3.

  On the other hand, the lamp post 5 is fixed on the case 2 when the protrusion 5a is inserted into a through hole (not shown) formed in the case 2 and engaged therewith. The lamp post 5 is formed with a C-shaped protruding piece 5b having an opening at a portion located on the liquid crystal panel 1 side. The cold cathode tube 3 supported by the lamp holder 4 is fitted into the projecting piece 5 b of the lamp post 5 while being forcibly bent. In the present embodiment, with respect to the height of the portion supporting the cold cathode tube 3 from the case 2, the support portion at the lamp holder 4 is higher than the support portion at the lamp post 5.

  Thus, the cold-cathode tube 3 is supported by the lamp holder 4 and the lamp post 5 and is held in a deflected posture by the support. Both ends of the cold-cathode tube 3 are closer to the liquid crystal panel 1 than the central portion with respect to the distance from the liquid crystal panel 1. It is getting closer.

  Further, the reflector 8 is overlaid on the inner surface of the case 2, and the diffusion plate 9 is overlaid on the back surface of the liquid crystal panel 1 (see FIGS. 2 and 3). That is, the reflector 8 is disposed on the back side of the cold cathode tube 3, and the diffusion plate 9 is disposed between the liquid crystal panel 1 and the cold cathode tube 3.

  Visible light from the cold cathode tube 3 reaches the diffusion plate 9 directly or through reflection by the reflection plate 8 and diffuses through the diffusion plate 9 to illuminate the entire area of the liquid crystal panel 1 from the back. At this time, in this embodiment, even if the luminance of the cold cathode tube 3 is low at both ends, the both ends are held in a manner closer to the liquid crystal panel 1 than the central portion. The illuminance is substantially uniform from end to end in the direction along the cold cathode tube 3. Therefore, the liquid crystal panel 1 has uniform brightness over the entire area, and the occurrence of uneven brightness can be suppressed.

  In addition, this invention is not limited to said embodiment, A various change is possible in the range which does not deviate from the meaning of this invention. For example, as for the support position of the cold cathode tube 3 by the lamp post 5, in the above embodiment, the central portion of the cold cathode tube 3 is one place, but as long as it is between the lamp holders 4, a position other than the central portion is provided. Or a plurality of locations. However, when the cold cathode tube 3 is supported by the lamp post 5 at one central portion as in the above embodiment, it is practical because the amount of bending of the cold cathode tube 3 can be easily set.

  In addition, the portion of the lamp post 5 that supports the cold cathode tube 3 is a C-shaped projecting piece 5b having an opening on the liquid crystal panel 1 side in the above-described embodiment. As shown in FIG. 4, the C-shaped projecting piece 5b may have a mouth open in a direction perpendicular to the liquid crystal panel side.

  The present invention is useful for a direct type liquid crystal panel illumination device.

It is a top view of the liquid crystal panel illuminating device which is one Embodiment of this invention. It is sectional drawing which shows the AA cross section of the liquid crystal panel illuminating device of FIG. It is sectional drawing which shows the BB cross section of the liquid crystal panel illuminating device of FIG. It is sectional drawing which shows the modification of the liquid crystal panel illuminating device of this invention. It is a top view of the conventional liquid crystal panel illuminating device. It is sectional drawing which shows CC cross section of the liquid crystal panel illuminating device of FIG. It is sectional drawing which shows DD cross section of the liquid crystal panel illuminating device of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid crystal panel 2 Case 3 Cold-cathode tube 4 Lamp holder 4a Projection 5 Lamp post 5a Projection 5b Projection part 6 Spacer 7 Lamp frame 8 Reflecting plate 9 Diffusion plate

Claims (3)

A plurality of cold cathode tubes arranged side by side on the back side of the liquid crystal panel, a lamp holder for supporting both ends of these cold cathode tubes, and a lamp post for supporting the cold cathode tubes between the lamp holders In a liquid crystal panel lighting device comprising:
The cold-cathode tube is supported at the center by the lamp post and is held in a bent state by the support by the lamp holder and the lamp post so that both ends are closer to the liquid crystal panel than the center. A liquid crystal panel lighting device. A plurality of cold cathode tubes arranged side by side on the back side of the liquid crystal panel, a lamp holder for supporting both ends of these cold cathode tubes, and a lamp post for supporting the cold cathode tubes between the lamp holders In a liquid crystal panel lighting device comprising:
The cold cathode tube is supported by the lamp holder and the lamp post, and is held in a bent state so that both end portions are closer to the liquid crystal panel than the center portion.   The liquid crystal panel illumination device according to claim 2, wherein the lamp post supports a central portion of the cold cathode tube.

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