JPH086017A - Metal mold structure of photoconductor for back light unit - Google Patents

Abstract

PURPOSE:To provide a metal mold structure which is cable of easily forming plural kinds of photoconductors having different patterns and are rational and cost effective in operation without exchanging metal molds. CONSTITUTION:A plate material 15 inscribed with corresponding patterns for forming patterns for improving luminance is freely attachably and detachably mounted at the metal mold 11a of the metal mold structure for photoconductors for a back light unit and the photoconductors having the patterns for improving luminance are formed at the time of injection molding of the photoconductors.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold structure for a light guide for a backlight unit.

[0002]

2. Description of the Related Art A backlight unit of a liquid crystal display device comprises a light source and a light guide plate for irradiating light from a light source incident from the side onto the entire diffusion surface (panel).
A predetermined pattern (uniformizing means) made of a rough surface is formed on the lower surface of the light guide plate to achieve uniform irradiation (improvement of brightness distribution).

Such a pattern is usually formed by previously engraving a corresponding pattern in the recessed portion (planar portion) of an injection molding die in which the light guide shape is recessed by an etching method. By using it, it is simultaneously formed (pattern transfer) on one surface of the light guide at the time of injection molding of the light guide.

[0004]

However, in the above-described conventional mold structure, an expensive and large mold is dedicated such as one mold for one pattern, and therefore each pattern is expensive. Have to own
In addition, there is an inconvenience that the mold must be completely replaced every time the pattern is changed.

Therefore, the present invention provides a rational and work-economical mold structure capable of easily forming a plurality of types of light guides having different patterns without exchanging the molds. That is the subject.

[0006]

In order to solve the above-mentioned problems, the present invention provides a mold structure for a light guide for a backlight unit, in which a plate material engraved with a corresponding pattern for forming a pattern for improving brightness is provided. , Detachably attached to the mold,
It is a structural feature that a light guide having a brightness improving pattern is formed during injection molding of the light guide.

[0007]

When the light guide body is injection-molded, the brightness improving pattern is favorably formed on the light guide body by the corresponding pattern of the plate material. Further, since the plate material can be easily replaced, it is possible to easily and quickly cope with injection molding of various kinds of light guides having different patterns.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view of a main part of an embodiment of a mold structure of a light guide for a backlight unit according to the present invention, viewed from the upper side along a PL line, and FIG. 2 is a mold viewed from a side direction. FIG. 3 is a cross-sectional view of the main part of FIG. 3, and FIG. 3 is a cross-sectional view of the main part of the mold seen from another side surface direction.

2 and 3, the upper side of the PL line is the fixed side (cavity side) mold 11 (11a), and the lower side is the movable side (core side) mold 11 (11b). Is. The rectangular recess 13 on the surface (lower surface) of the fixed mold 11a has one surface (lower surface) formed by etching.
In addition, a rectangular plate material 15 for pattern formation on which a predetermined pattern (rough surface) not shown is formed (specifically, for example,
A stainless-steel SUS304 mirror-finish plate BA / N0.8S manufactured by Taihua Kogyo Co., Ltd. is attached in a fitting manner by six plate material mounting bolts 17. This plate material 1
The pattern 5 (not shown) is a rough surface pattern (uniformizing means) for realizing uniform irradiation (improvement / uniformization of luminance distribution), and the plate material 15 is a broken line in FIG. The shaded area in FIG. 1 indicates the pattern area (or etching processing area).

On the other hand, on the corresponding surface of the movable mold 11b, a rectangular light guide body forming recess 19 smaller than the pattern forming plate 15 (that is, the thickness of the light guide body (for example, the thickness of the light guide body) is used. A recess) having a depth of about 4 mm) is formed. In addition, in order to prevent the head of the plate material mounting bolt 17 from interfering with the corresponding portion of the movable mold 11b,
An escape hole 21 is formed.

The mold 1 of this embodiment having such a structure
The injection molding process performed by using No. 1 will be briefly described below. First, for example, a PMMA resin material (for example, a product name Delpet 80NR manufactured by Asahi Kasei Co., Ltd.) which is in a fluidized state by heating and melting in an injection cylinder (not shown).
Is injected (supplied) into the mold through the gate unit 23.
Then, through the cooling and solidification, the light guide 25 (molded product) having a pattern (transfer) is formed. Then, when the mold is opened, the molded product (light guide 25) is taken out by the ejector pin 27 (FIG. 3), thereby completing one molding cycle. By repeating the above cycle process, a large amount of light guides can be continuously manufactured.

Next, in the case of manufacturing a light guide having a pattern different from that described above, in the conventional case, it would be a laborious work of exchanging dies, and the setup work takes a very long time. Although (including the mold temperature setting time) has just been broken, this is not the case in the present embodiment. That is, in the mold open state, the pattern forming plate material (15) can be easily and easily replaced by attaching and detaching the above-described six plate material mounting bolts 17, so that the pattern forming plate material (15) can be replaced next in a short time. Another type of light guide can be injection molded.

As described above, in this embodiment, since the pattern is not directly formed on the die, the pattern forming plate material can be easily formed without replacing (or partially disassembling) the die. It is possible to switch to another pattern just by exchanging it (shortening the setup time (man-hours)). Therefore, various types of light guides with different patterns can be injection-molded inexpensively, easily and quickly (multi-product small-volume production). can do. Further, by removing the plate material, the plate material can be easily washed, which is preferable for maintenance. Furthermore, since it is not necessary to have many molds, that is, only lightweight, compact, and inexpensive plate materials are required, it is extremely preferable in terms of management and economy. Furthermore, only by exchanging the plate material for pattern formation,
Since it is possible to easily and inexpensively perform the trial manufacture of the pattern, it becomes possible to supply the high-quality and low-cost light guide body to the market in a timely manner.

It has been experimentally recognized that it is possible to form a light guide body without pattern transfer (that is, a mirror finished surface).

[0015]

As described above, according to the present invention, it is possible to realize a reasonable and economical mold structure capable of satisfactorily solving the above-mentioned conventional inconveniences.

[Brief description of drawings]

FIG. 1 is a plan view of an essential part of an embodiment of a mold structure of a light guide for a backlight unit according to the present invention, viewed from the upper side along a PL line.

FIG. 2 is a cross-sectional view of a main part of a mold seen from a side surface direction.

FIG. 3 is a cross-sectional view of a main part of the mold seen from another side surface direction.

[Explanation of symbols]

 11, 11a, 11b ... Mold 13 ... Rectangular recess 15 ... Plate material 17 ... Bolt 19 ... Recess 21 ... Relief hole 23 ... Gate part 25 ... Light guide 27 ... Ejector pin

Claims (1)

[Claims] 1. In a mold structure of a light guide for a backlight unit, a plate material (15) engraved with a corresponding pattern for forming a brightness improving pattern is detachably attached to the mold (11). The mold structure is characterized in that a light guide having a brightness improving pattern is formed during injection molding of the light guide.