JP3543061B2 - Manufacturing method of light guide plate - Google Patents

Description

[0001]
[Field of the Invention]
The present invention relates to a method for manufacturing a light guide plate used for a backlight for a liquid crystal, a display panel for a game machine, and the like, and more particularly, to a method for manufacturing a light guide plate in which light transmitted from a light source has uniform brightness over the entire surface of the light guide plate. It relates to a manufacturing method.
[0002]
[Prior art]
Conventionally, a light guide plate used for a liquid crystal backlight, a display panel for a game machine, or the like is formed of a synthetic resin having excellent light transmittance, such as acrylic or polycarbonate, and is disposed on one end or the back surface of a small surface of the light guide plate. Light is transmitted from the light source to illuminate the surface with high brightness. However, since the amount of light transmitted from the light source to the surface of the light guide plate decreases in inverse proportion to the distance from the light source, the surface of the light guide plate cannot be illuminated with uniform brightness. Therefore, it is conventionally known to print a pattern having a density that is inversely proportional to the decrease in the amount of light from the light source on the surface of the light guide plate so that the surface of the light guide plate has uniform brightness. As a printing method of a pattern having shading, a dot pattern by screen printing, grain printing, and the like are generally known. However, the printing of such a shaded pattern is possible when the surface of the light guide plate is finished to a flat surface by cutting or the like, but it is possible to print a three-dimensional pattern such as a box shape or an uneven shape. It could not be applied in the case where the surface had distortion or distortion due to having a shape or being an injection molded product. In this specification, the term “pattern” does not mean only a specific pattern, but is used as a word including various designs, patterns, shapes, or colors.
[0003]
JP-A-6-333407 discloses a method in which a photosensitive ink is applied to the surface of an acrylic plate or a polycarbonate plate, a film having a dot pattern is superposed, exposed and developed to form a pattern having shading on the light guide plate. Is disclosed. According to such a method, there is an advantage that a shading pattern can be formed on a flat surface even if it has a three-dimensional shape such as a box shape. However, when the surface has unevenness, distortion, or distortion, there is a problem that it is not possible to expect formation of an accurate light and shade pattern due to a difference in exposure amount.
[0004]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION It is an object of the present invention to form an accurate light and shade pattern regardless of the surface shape and properties of a light guide plate so that the surface of the light guide plate has uniform brightness.
[0005]
[Means for Solving the Problems]
This invention taken means to solve the above problems, outwardly a single fixed projection on one side of the resin film protruding from the ear, the portion other than the fixing protrusion Inject the light-transmitting resin that will be the light guide plate while holding the resin film floating inside the mold by holding only the fixing projections with the lower mold and the upper mold without holding It is characterized in that a resin film is integrally laminated on the surface of the light guide plate.
[0006]
Further, the pattern printed on the resin film is formed by dot printing or grain printing.
[0007]
Furthermore, the film holding pressure of the mold for injection molding, forming a gap slightly smaller than the film thickness in the film holding portion of the upper and lower mold corresponding to the film thickness, does not affect the film It is characterized by pressure.
[ 0008 ]
BEST MODE FOR CARRYING OUT THE INVENTION
Preferred embodiments of the present invention will be described in detail below. In the figure, (1) is a resin film on the surface of which a pattern ( 2 ) is applied by dot printing or grain printing with a density that is inversely proportional to the decrease in the amount of light from the light source, and has a thickness of about 175 μm to 188 μm. The illustrated resin film has a pattern adapted to be illuminated from one edge of the light guide plate printed thereon. However, it is a matter of course that printing is appropriately performed according to the position of the light source. In the illustrated resin film, a pattern ( 2 ) is provided such that the light source is located on the left-hand foreface .
[ 0009 ]
The resin film (1) is formed with an inverted trapezoidal ear-shaped fixing protrusion (3) for fixing the resin film into the injection mold. The fixing projection (3) is provided with a semicircular notch at the center of the tip, and a notch is formed on the side surface. The fixing protrusion (3) is compressed and held by the lower mold (4) and the upper mold (5) to be fixed in the mold. In the mold, only the fixing projection (3) is fixed, and the main body of the resin film (1) is not fixed. Further, the shape of the fixing projection (3) is not limited to an inverted trapezoid.
[ 0010 ]
【Example】
2 to 7 show injection molding of the light guide plate (6) and insert molding of the resin film (1). A resin film (1) on which a pattern (2) is applied by printing means in a density that is inversely proportional to the decrease in the amount of light from the light source is formed so that the fixing projection (3) abuts on the fixing step (42). After setting in the storage recess (41) of the lower mold (4), the upper mold (5) for molding is applied and the mold is closed. Although not shown, the fixing step (42) or the surface of the upper die joining surface (51) is provided at the position corresponding to the notch provided on the fixing projection (3) of the resin film. By providing the pins, the fixing of the resin film (1) becomes more reliable.
[ 0011 ]
FIG. 7 shows the vicinity of the injection hole (52) when the resin film (1) is set and the mold is closed. When the upper and lower molding dies (4) and (5) are closed, it is designed so that a gap of about 150 μm is generated between the upper die joining surface (51) and the fixing step (42), The resin film (1) is sandwiched and fixed in this gap. Since the resin film (1) has a thickness of about 175 μm to 188 μm, the resin film (1) is sandwiched and fixed in a state where the thickness is compressed by about 25 μm to 38 μm by the fixing step (42) and the joining surface (51). However, with such a degree of compression, the resin film (1) is securely fixed without breaking. There is a step of about 0.5 mm between the fixing step (42) and the storage recess (41). For this reason, the resin film (1) floats from the mold near the fixing projection (3), but the resin film (1) adapts to the mold due to the heat and pressure of the resin during resin injection. It is integrally laminated on the surface of 6), and has an end as it is. Thus, a gap slightly smaller than the thickness of the film is formed in the portion of the upper mold and the lower mold that sandwich the ear-shaped protrusions, and the pressure for clamping the film corresponds to the film thickness. By reducing the size, there is no fear that the film is compressed by a molding die to cause wrinkles.
[ 0012 ]
FIG. 4 shows a state in which a light-transmitting resin such as acryl or polycarbonate is injected from a resin injection hole (52) provided in the upper mold for molding (5) to fill the space in the mold with the resin. In this state, the resin film (1) is integrally laminated on the surface of the injected resin by heat and pressure to form the light guide plate ( 6 ) . As shown in FIG. 5, the formed light guide plate (6) is in a state where the resin film (1) is laminated, but only the fixing projection (3) projects from the end. Therefore, to complete this protruding fixing projections (3) by cutting the light guide plate (6).
[ 0013 ]
According to the method for manufacturing a light guide plate of the present invention, a pattern can be applied to the light guide plate at a density that is inversely proportional to the decrease in the amount of light from the light source, so that a light guide plate with uniform brightness over the entire light guide plate can be provided. Further, in addition to it is possible to reduce the cost can be fully automated stroke of the molding from the film printing, so resulting in laminating together the printed film design at the time of injection molding of the light guide plate, to perform the printing after the molding The light guide plate can be easily formed even if the shape is difficult, and the shape of the molded product can be diversified. An automatic machine such as a cylinder press type silk printing machine can form a uniform printing surface, but cannot handle thick materials. When printing is used, an automatic machine could not be used, and printing had to be performed by a semi-automatic machine, and it was difficult to form a uniform printing surface. In the present invention, since the shading pattern is printed on a thin film, printing by an automatic machine can be performed, and it is easy to obtain a uniform printing surface. Furthermore, even if an error occurs in the printing of the light and shade patterns, the present invention stops the disposal of only the film and eliminates the necessity of disposing of the molded product, so that the resources can be effectively used. On the other hand, when pattern printing is performed directly on a conventional molded product, there is a disadvantage that if a mistake occurs, the entire molded product must be discarded.
[ 0014 ]
【The invention's effect】
According to the present invention, since the resin film on which the pattern is printed is held in a state in which the resin film is held in the mold by the ear-shaped fixing projections and held in the mold, regardless of the shape of the surface of the light guide plate. The resin film on which the pattern is printed can be integrally laminated at the time of injection molding of the light guide plate, and the light guide plate can be easily molded even if it is difficult to print after molding, and the shape of the molded product can be varied. Can be
[Brief description of the drawings]
FIG. 1 is a perspective view showing the appearance of a light guide plate according to the present invention. FIG. 2 is a diagram showing the relationship between a lower mold for molding and a resin film. FIG. 3 is a diagram showing a mold for molding. FIG. 5 is a view showing a light guide plate immediately after molding. FIG. 6 is a view showing a completed light guide plate. FIG. 7 is an enlarged cross-sectional view near an injection hole in a state where a molding die is closed.
(1) Resin film
(2) Design
(3) Fixing projection
(4) Lower mold for molding
(41) Storage recess
(42) Fixing step
(43) Joint surface
(5) Upper mold for molding
(51) Joint surface
(52) Resin injection hole
(6) Light guide plate
(7) Light source

Claims (3)

The resin film printed with patterns, the surface of the molded body made of a light transmitting resin, a process for the preparation of the light guide plate by one body to lamination, single fixed projection on one side of the resin film Is projected outward in the shape of an ear , and portions other than the fixing protrusion are not pinched, and only the fixing protrusion is pinched by the lower mold and the upper mold, and the resin film is placed in the mold. A method of manufacturing a light guide plate, wherein a light-transmitting resin serving as a light guide plate is injected while holding the resin film in a floating state, and a resin film is integrally laminated on a surface of the light guide plate. The method for manufacturing a light guide plate according to claim 1, wherein the pattern printed on the resin film is formed by dot printing or grain printing. The film holding pressure of the mold for injection molding is adjusted to the pressure that does not affect the film by forming a gap slightly smaller than the film thickness in the film holding part of the upper and lower molds corresponding to the thickness of the film. The method for manufacturing a light guide plate according to claim 1, wherein:

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