JPH081052Y2 - Light guide mold - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention is installed inside an instrument installed in, for example, an automobile, and guides light from a light source installed inside the instrument to an instrument panel or a pointer. The present invention relates to a light guide mold used for illuminating.

[Prior Art] Conventional examples of this type of light guide include, for example, FIGS.
The light guide plate 1 has a shape as shown in the drawing, and is substantially rectangular in plan view, and has a semicircular recess 3 formed in one side edge thereof for allowing the light bulb 2 to enter. .
The light guide plate 1 is formed by using a transparent resin material as a raw material, and can be formed by using a forming die as shown in FIG. 5, for example. This light guide plate molding die 4
Has a cavity die 6 having a cavity surface 5 and a pressing die 7 which covers the upper surface of the cavity die 6, and an injection port 8 provided in the pressing die 7 after closing both the die 6, 7. By further press-fitting a transparent resin material, the light guide plate 1 having the shape as shown in FIGS. 3 and 4 is formed.

[Problems to be Solved by the Invention] However, as a mold surface 5 of a mold 6 for molding the light guide plate 1, a polishing mark 9 for finishing the mold surface to be a flat surface, that is, a polishing material such as a file is used. Since the fine streak lines 9 generated during polishing are formed in the direction orthogonal to the long sides of the rectangular cavity surface, the light guide plate 1 molded using this cavity mold 6 has a structure as shown in FIG. , A fine line pattern 9'corresponding to the fine line 9 is produced. Since the line direction of the streak pattern 9'is a direction intersecting with the light guiding direction (A) of the light bulb 2, diffuse reflection due to the fine line pattern 9'occurs, and the tip direction of the light guide plate 1 is generated. There is a drawback in that the light guide toward (the edge opposite to the edge having the light bulb 2) is obstructed, and it is difficult to obtain a desired light guide amount.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned conventional drawbacks. The cavity type surface polishing for forming the light guide plate is performed in the light guide direction of the formed light guide plate. The polishing material is operated along with it, and a molding die is formed in which minute streaky polishing marks in the light guide direction are formed on the cavity surface thereof. Therefore, when the light guide plate is molded using this mold, the streaks of the polishing marks formed on the cavity surface are formed along the light guide direction of the light guide plate. Due to the action of the traces, irregular reflection (attenuation of light) in the middle of the light guide plate is reduced, and the light guide efficiency of light introduced from one end thereof is enhanced.

[Embodiment] The present invention will be described in detail below with reference to an embodiment shown in FIGS. 1 and 2. The same parts of the structure of this embodiment and the structure described in the conventional example are the same as those in the conventional example. The same reference numerals are used and the description of the same structural parts is omitted.

That is, in the present embodiment, when the cavity surface of the mold for resin-molding the rectangular light guide plate 1 as shown in FIG. 1 is polished and finished, the polishing direction of the abrasive used for the polishing is It is determined in the long side direction of the rectangular light guide plate 1, that is, in the light guide direction.

Therefore, according to this embodiment, fine scratches 10 generated by transferring the polishing scratches on the cavity surface to the molded product 1 are formed along the light guiding direction of the light bulb 2.
The light guide is effectively guided to the tip portion along the traces 10, and diffuse reflection in the middle of the light guide plate 1 is eliminated, so that a light guide plate having high light guide efficiency can be provided.

In this embodiment, the streak 10 is formed in the radial direction with the light bulb 2 as the center, but the present invention is not limited to this, and a number of streak lines parallel to the long side of the molded article 1 are provided. May be

[Advantages of the Invention] As described above, the present invention is a mold for molding a light guide 1 made of a transparent material, in which the mold surface is polished in the same direction as the light passing direction of the light guide. Therefore, since the polishing traces are transferred to the light guide formed by this mold in the direction in which the light from the light source should be guided, the polishing traces improve the light guiding efficiency. The effect is obtained.

[Brief description of drawings]

FIG. 1 is an explanatory plan view showing an embodiment of a light guide formed by a molding die according to the present invention, FIG. 2 is a side view thereof, and FIG. 3 is an explanatory plan view of a conventional light guide. Fig. 4 is its side view,
FIG. 5 is an explanatory view of a molding die for molding a conventional light guide. 1 ... Light guide, 2 ... Light bulb 10 ... Polishing streak

Claims (1)

[Scope of utility model registration request] 1. A light guide molding die, comprising: a mold for molding a light guide (1) made of a transparent material, the mold surface of which is polished in the same direction as the light passage direction of the light guide.