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"Light Guide Plate Producing Method, Die Structure, Transfer Molding Apparatus, Light Guide Plate, Area Light Source Device, Liquid Crystal Display...

May 29, 2014



"Light Guide Plate Producing Method, Die Structure, Transfer Molding Apparatus, Light Guide Plate, Area Light Source Device, Liquid Crystal Display Device, and Mobile Device" in Patent Application App

By a News Reporter-Staff News Editor at Politics & Government Week -- A patent application by the inventors Makuta, Isao (Saitama, JP); Takemura, Koichi (Shiga, JP); Shibata, Tomofusa (Kyoto, JP); Yamanaka, Yoshihisa (Shiga, JP); Kitamura, Norikazu (Shiga, JP); Shinohara, Masayuki (Kyoto, JP); Hirota, Kazuhide (Shiga, JP); Taguchi, Yoshikaga (Shiga, JP); Kojima, Masayuki (Shiga, JP); Takahashi, Yukihiro (Kyoto, JP), filed on February 8, 2013, was made available online on May 15, 2014, according to news reporting originating from Washington, D.C., by VerticalNews correspondents.

This patent application is assigned to Omron Corporation.

The following quote was obtained by the news editors from the background information supplied by the inventors: "The present invention relates to a light guide plate producing method, a die structure, a transfer molding apparatus, a light guide plate, an area light source device, a liquid crystal display device, and a mobile device.

"Conventionally, there is well known a transfer molding apparatus that heats and pressurizes a resin film with a transfer plate to perform transfer molding of a fine irregular pattern (for example, see Japanese Unexamined Patent Publication No. 2005-310286).

"However, in the conventional transfer molding apparatus, for example, only a fine irregular pattern of a sub-micrometer scale can be formed on a surface of the resin film, but a sub-millimeter-scale structure cannot simultaneously be formed."

In addition to the background information obtained for this patent application, VerticalNews journalists also obtained the inventors' summary information for this patent application: "One or more embodiments of the present invention is not only be able to transfer a transfer surface to the resin sheet, but also form a thick portion in which a projection is greater than a maximum height of irregularity of the transfer surface.

"In accordance with one or more embodiments of the present invention, a method for producing a light guide plate including: a light introduction part that introduces light incident through an end face; and a light guide plate body that has a thickness less than a maximum thickness of the light introduction part, the light guide plate body being provided so as to be continuously joined to the light introduction part, the light guide plate body causing a light controller to output the incident light to an outside, the light guide plate producing method includes: a conveying step of conveying a resin sheet between a first die and a second die, which are disposed while facing each other, a transfer surface being provided in at least one of surfaces facing each other in the first and second dies; a nipping step of nipping the resin sheet between the first and second dies while the transfer surface is abutted on at least one of surfaces of the resin sheet; and a transfer molding step of transferring the transfer surface to at least one of the surfaces of the resin sheet by heating at least one of the first and second dies, and of forming a thick portion in one of the surfaces of the resin sheet by a recess where the light introduction part formed in the die is formed, a projection size of the thick portion being greater than a maximum height of an irregularity where the light controller formed in a surface of the transfer surface is formed.

"In a light guide plate producing method according to one or more embodiments of the present invention, the first and second dies are further brought close to each other in the transfer molding process such that a thickness of the light guide plate body of the post-transfer-molding resin sheet is less than an initial thickness of the post-transfer-molding resin sheet.

"In a light guide plate producing method according to one or more embodiments of the present invention, the projection size of the light introduction part of the post-transfer-molding resin sheet is greater than or equal to ten times the maximum projection size of the light controller in the transfer molding step.

"In a light guide plate producing method according to one or more embodiments of the present invention, the resin sheet is heated to a glass transition temperature or more in the transfer molding step.

"In a light guide plate producing method according to one or more embodiments of the present invention, the light introduction part is formed by melting and introducing the resin sheet to the recess formed in the transfer surface in the transfer molding step.

"In a light guide plate producing method according to one or more embodiments of the present invention, the resin introduced to the recess of the transfer surface is a surface portion of the molten resin sheet.

"In a light guide plate producing method according to one or more embodiments of the present invention, the resin introduced to the recess of the transfer surface is obtained from a region adjacent to a region that constitutes a product after the transfer molding of the resin sheet.

"In a light guide plate producing method according to one or more embodiments of the present invention, an additional member is disposed in the recess, and melted together with at least part of the resin sheet to form the light introduction part in the transfer molding step.

"In a light guide plate producing method according to one or more embodiments of the present invention, the resin sheet includes a projection in at least part thereof, and the light introduction part is formed by melting at least the projection in the transfer molding step.

"In accordance with one or more embodiments of the present invention, there is provided a die structure that is used to mold a light guide plate, the light guide plate including: a light introduction part that introduces light incident through an end face; and a light guide plate body in which a thickness is less than a maximum thickness of the light introduction part, the light guide plate body being provided so as to be continuously joined to the light introduction part, the light guide plate body outputting the incident light to an outside with a light controller, the die structure includes: a first die; a second die that can relatively be separated from and come into contact with the first die; a heater that is provided in at least one of the first and second dies; and a transfer member that is provided in at least one of the first and second dies, the transfer member performing transfer molding while abutting a transfer surface on a resin sheet supplied between the first and second dies, wherein a recess where the light introduction part is formed on a side of at least one of the transfer surfaces and an irregularity where the light controller is formed are formed in the transfer member.

"In a die structure according to one or more embodiments of the present invention, a depth of the recess is greater than or equal to ten times of a maximum height of the irregularity formed in the transfer surface.

"In a die structure according to one or more embodiments of the present invention, the first and second dies can be brought close to each other such that a thickness of the post-transfer-molding resin sheet is less than an initial thickness of the resin sheet.

"In a die structure according to one or more embodiments of the present invention, the heating part can heat the resin sheet to a glass transition temperature or more.

"In a die structure according to one or more embodiments of the present invention, the heating part can partially heat the recess such that a temperature at the recess is higher than that at other portions.

"In accordance with one or more embodiments of the present invention, a transfer molding apparatus includes the die structure in accordance with one or more embodiments of the present invention.

"In accordance with one or more embodiments of the present invention, a light guide plate is formed by the method in accordance with one or more embodiments of the present invention.

"In accordance with one or more embodiments of the present invention, an area light source device includes: the light guide plate in accordance with one or more embodiments of the present invention; and a light source that is disposed in at least one of end faces of the light guide plate.

"In accordance with one or more embodiments of the present invention, a liquid crystal display device includes: the area light source device in accordance with one or more embodiments of the present invention; and a liquid crystal panel.

"In accordance with one or more embodiments of the present invention, a mobile device includes the liquid crystal display device in accordance with one or more embodiments of the present invention.

"According to one or more embodiments of the present invention, the transfer surface can be transferred to the resin sheet, but also the thick portion having the large projection in which the scale is different from that of the surface roughness of the transfer surface can simultaneously be formed by the recess formed in the dies.

BRIEF DESCRIPTION OF THE DRAWINGS

"FIG. 1 is a schematic front view illustrating a light guide plate forming apparatus according to a first embodiment;

"FIG. 2 is a partially exploded perspective view schematically illustrating a transfer molding apparatus in FIG. 1;

"FIG. 3A is a partial plan view of an upper-die transfer plate in FIG. 2, FIG. 3B is a partially schematic sectional view of a die portion in FIG. 2, and FIG. 3C is a partially enlarged view of the die portion in FIG. 2;

"FIG. 4A is an explanatory view illustrating a relationship between a half-finished plate and first and second cutting tools, and FIGS. 4B and 4C are explanatory views illustrating a relationship between the half-finished plate and the first cutting tool;

"FIG. 5A is a photograph illustrating a lighting state of a light guide plate of the first embodiment, FIG. 5B is a photograph illustrating a lighting state of a conventional light guide plate, and FIG. 5C is a graph illustrating transmitted light amounts of the lighting states in FIGS. 5A and 5B;

"FIG. 6 is a schematic perspective view illustrating a light guide plate forming apparatus according to a second embodiment;

"FIGS. 7AA-7AF are explanatory views illustrating a behavior of each plate in a transfer molding apparatus in FIG. 6;

"FIG. 7BA is a graph illustrating a change in elastic modulus of a resin sheet according to a temperature change of the resin sheet, and FIG. 7BB is a graph illustrating a change in residual stress according to the temperature change of the resin sheet;

"FIG. 8 is a graph illustrating a relationship between a temperature and an applied pressure in a die of the transfer molding apparatus in FIG. 6;

"FIGS. 9A-9D are explanatory views illustrating a behavior of each plate in a transfer molding apparatus according to a third embodiment;

"FIGS. 10E-10G are explanatory views illustrating the behavior of each plate in the transfer molding apparatus of the third embodiment;

"FIGS. 11AA-11AD are schematic explanatory views illustrating a method according to other embodiments for forming a thick portion from the resin sheet;

"FIGS. 11BA and 11BB are schematic explanatory views illustrating a method according to other embodiments for forming the thick portion from the resin sheet;

"FIGS. 11CA and 11CB is a are schematic explanatory views illustrating a method according to other embodiments for forming the thick portion from the resin sheet;

"FIGS. 11DA-11DD partially schematic sectional views illustrating a transfer plate and the resin sheet according to other embodiments;

"FIG. 11E is a sectional view illustrating a liquid crystal display device in which the light guide plate of the first embodiment is used; and

"FIG. 11F is a perspective view illustrating an area light source device in which the light guide plate of other embodiments is used."

URL and more information on this patent application, see: Makuta, Isao; Takemura, Koichi; Shibata, Tomofusa; Yamanaka, Yoshihisa; Kitamura, Norikazu; Shinohara, Masayuki; Hirota, Kazuhide; Taguchi, Yoshikaga; Kojima, Masayuki; Takahashi, Yukihiro. Light Guide Plate Producing Method, Die Structure, Transfer Molding Apparatus, Light Guide Plate, Area Light Source Device, Liquid Crystal Display Device, and Mobile Device. Filed February 8, 2013 and posted May 15, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=4306&p=87&f=G&l=50&d=PG01&S1=20140508.PD.&OS=PD/20140508&RS=PD/20140508

Keywords for this news article include: Omron Corporation.

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Source: Politics & Government Week