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Patent Issued for Planar Light Source Device and Liquid Crystal Display Device Using the Same

February 12, 2014



By a News Reporter-Staff News Editor at Journal of Engineering -- According to news reporting originating from Alexandria, Virginia, by VerticalNews journalists, a patent by the inventor Arita, Kenji (Tokyo, JP), filed on October 22, 2010, was published online on January 28, 2014.

The assignee for this patent, patent number 8638404, is Mitsubishi Electric Corporation (Tokyo, JP).

Reporters obtained the following quote from the background information supplied by the inventors: "The present invention relates to a planar light source device used in an image display device such as a liquid crystal display device and a liquid crystal display device using the same.

"In a related planar light source device, for example a planar light source device for a non-spontaneous light-emitting display device such as a liquid crystal display device, a side light type (also called an edge light type) and a direct type are known. The side-light-type planar light source device has a structure in which a light source is disposed on a side surface portion of a mold frame included in a rear frame. The direct-type planar light source device has a structure in which a light source is disposed on a rear surface of a mold frame facing a display unit.

"Further, in the side-light-type planar light source device, a light guiding plate is provided to guide the light emitted from the light source to a desired direction, and the light emitted from the light source, for example a line light source such as a cold cathode fluorescent lamp (hereinafter, referred to as a CCFL) or a point light source such as a light emitting diode (hereinafter, referred to as an LED), is reflected inside the light guiding plate. And then, the light is diffused by a diffusion pattern provided inside the light guiding plate, and the light is emitted to the light emission surface. When the light guiding plate is provided, a display panel such as a liquid crystal panel is provided on the display surface side of the light guiding plate. A front frame having an opening and supporting the display panel, a mold frame, and a rear frame are disposed on the display surface side of the display panel.

"Furthermore, in order to efficiently emit the light emitted from the light source to the display panel, an optical sheet, for example a prism sheet for improving regularity or a reflection sheet for reflecting the light toward the light guiding plate or the display panel, is also provided. Here, the optical sheet is also accommodated between the rear frame and the mold frame as in the light source or the light guiding plate. In addition, the reflection sheet is disposed between the light guiding plate and the rear frame.

"Accordingly, in the related planar light source device, the number of components was large. Specifically, the structure of the mold frame was complex and the cost of the mold was very expensive. Therefore, a related art is known for obtaining a cheap and light weight liquid crystal display device where the number of components thereof have been decreased by forming the reflection sheet and removing the mold frame (for example, refer to JP-A-2009-145858, Page 3 to 5, FIG. 1).

"In the related art, when the optical member such as an optical sheet or a light guiding plate is provided, the optical member is disposed inside the reflection sheet, which was shaped, instead of the mold frame. For this reason, there is a problem that the positioning operation of the optical sheet is difficult when inserting the optical sheet. In addition, in the insertion operation of the optical sheet, there is also a problem that is called as erroneous insertion caused by the front side and the rear side of the optical sheet are reversed. However, such erroneous insertion of the optical sheet is not described in the JP-A-2009-145858."

In addition to obtaining background information on this patent, VerticalNews editors also obtained the inventor's summary information for this patent: "The present invention has been made with consideration of the above problem, and an object of the present invention is to provide a planar light source device in which a positioning operation of an optical member such as an optical sheet is easily performed, in the planar light source device in which the mold frame is replaced by a reflection sheet.

"The planar light source device according to one aspect of the invention is a planar light source device without a mold frame, and the shaped reflection sheet has a portion, which is used to position the optical member such as an optical sheet.

"According to the aspect of the invention, it is possible to obtain the planar light source device where the number of components can be decreased by removing the mold frame and the positioning operation of the optical member may be easily performed."

For more information, see this patent: Arita, Kenji. Planar Light Source Device and Liquid Crystal Display Device Using the Same. U.S. Patent Number 8638404, filed October 22, 2010, and published online on January 28, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=46&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=2271&f=G&l=50&co1=AND&d=PTXT&s1=20140128.PD.&OS=ISD/20140128&RS=ISD/20140128

Keywords for this news article include: Mitsubishi Electric Corporation.

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Source: Journal of Engineering


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