JP3603952B2 - Method for manufacturing resin transparent display - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a resin light-transmitting display body in which a light-transmitting resin portion is surrounded by a light-shielding resin portion and a light-transmitting portion for transmitting light from a light source behind is formed, and a method of manufacturing the same.
[0002]
[Prior art]
This kind of resin light-transmitting display is usually provided so that a light source faces behind a plurality of light-transmitting resin parts, and a light-transmitting resin is provided to prevent light from reaching adjacent light-transmitting resin parts. A light-shielding resin portion is provided so as to surround the portion. The light source is turned on or off according to the switch operation of the operator or the control state by the control device, and the current state is displayed by the translucent resin part. Typical applications of the resin-made translucent display include electronic keyboard instruments and various control devices.
[0003]
Such a resin-made light-transmitting display body can be manufactured by separately forming a light-transmitting resin portion and a light-shielding resin portion and bonding them, but the process and curing time required for bonding are reduced. Omittable two-color molding is frequently used due to its convenience.
[0004]
However, in the conventional two-color molding, the two types of resin are provided with the integrity at the time of molding. In particular, in order to obtain the integrity equivalent to the bonding of the two resin portions, the light-shielding resin portion formed by the primary molding is used. The light-transmitting resin portions formed by the secondary molding are adhered to each other, and are formed so as to obtain a strong connection by welding therebetween.
[0005]
On the other hand, a resin-made translucent display is often attached to a panel and provided so as to guide light of a small chip-shaped light source such as an LED installed at the rear of the panel to the front of the panel. Usually, the light source is installed at a position distant to some extent from the panel surface due to the mounting structure, and the resin-made translucent display is arranged so that the end face is located as close as possible to the light source in order to improve the light receiving efficiency. Therefore, the resin light-transmitting display has a length extending from the panel surface to the vicinity of the light source.
[0006]
[Problems to be solved by the invention]
As described above, the light-transmitting resin portion of the resin-made light-transmitting display member having a certain length is in close contact with the light-shielding resin portion by welding. When the incident light reaches the interface (side surface) between the two resins, most of the light is absorbed by the light-shielding resin portion. Therefore, most of the light emitted from the outer end face on the panel surface side of the translucent resin portion is incident on the inner end face and travels to reach the outer end face without reaching the side face. As a result, the light from the light source cannot be effectively emitted from the translucent resin part, and it may be difficult to perform transmissive display with sufficient brightness. In particular, electronic musical instruments and control devices such as PAs are sometimes used outdoors. In this case, it is necessary to distinguish the display using a resin light-transmitting display under direct sunlight. It is difficult for the display to obtain a sufficient luminance that can respond to this.
[0007]
The present invention solves such a conventional problem, and a resin-made light-transmitting display body capable of efficiently emitting light from a light source from a light-transmitting resin portion to reliably perform light-emitting display with sufficient brightness, and a method of manufacturing the same. It is intended to provide a manufacturing method.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a resin light-transmitting display in which a light-transmitting resin portion is surrounded by a light-shielding resin portion and a column-shaped light-transmitting portion for transmitting light from a light source behind is formed. A method of manufacturing a body by a two-color molding method, wherein one of the two resin parts of the light-shielding resin part and the light-transmitting resin part is primarily molded, and injection molding is performed by incorporating the primary molded resin part. In the second molding, the other resin portion is subjected to secondary molding, and at the time of performing the secondary molding, an air layer is formed between the light-shielding resin portion and the light-transmitting resin portion without welding. An object of the present invention is to provide a method for manufacturing a resin-made translucent display characterized by increasing the injection speed .
In this manufacturing method, the light-shielding resin portion made of a crystalline resin material is injection-molded, the light-shielding resin portion is first molded, and the light-shielding resin portion that has been primarily molded is incorporated into a molding die. The light-transmitting resin portion can be second-molded by injection-molding a light-transmitting resin made of an amorphous resin material.
This manufacturing method also includes a state in which the light-shielding resin portion made of an amorphous resin material is injection-molded to first-mold the light-shielding resin portion, and the light-shielding resin portion primary-molded is incorporated into a mold. Then, the light-transmitting resin portion made of a crystalline resin material can be injection-molded to secondary-mold the light-transmitting resin portion.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 shows an example of a resin light-transmitting display. The display 1 has a configuration in which a lower portion of a translucent resin portion 2 is surrounded by a light-shielding resin portion 3. In this example, the translucent resin portion 2 is connected to six columnar bodies 20 each of which is a fine vertically-long rectangular parallelepiped and arranged in a straight line in a state where they are arranged in a straight line. And a flange portion 21 protruding therefrom. The upper end of the columnar body 20 forms a fitting portion 22 that is thinned so as to fit into an opening of a display panel described later.
[0010]
The light-transmitting resin portion 2 and the light-shielding resin portion 3 are connected to each other by two-color molding, as described later. As shown in FIGS. 1 and 2, the light-shielding resin portion 3 includes a surrounding portion 30 surrounding the lower four circumferences of each columnar body 20 of the light-transmitting resin portion 2, and one side of an upper portion of the columnar body 20. And a flange 32 projecting vertically from the upper end of the partition 31 in the direction in which the columnar bodies 20 are arranged.
[0011]
In the use state, the resin-made translucent display 1 is arranged so that the light source unit 4 is located below. The light source unit 4 includes a light source 40 using LEDs, and a support plate 41 that supports the light source so as to be located below each translucent resin unit. The light source is connected to the control unit by a conductor (not shown). The control unit turns on the light sources 40 individually or an appropriate number at the same time so as to indicate the control state of the electronic musical instrument and various control devices.
[0012]
In use, the display panel 5 is located above the resin light-transmitting display 1. The display panel 5 is generally a part of a casing of an electronic musical instrument main body, a control device, or the like. The display panel 5 has an opening 50 for receiving the fitting portion 22 at the upper end of the translucent resin portion 2. In the vicinity of the opening 50 of the display panel 5, control contents and the like corresponding to each translucent resin part 2 are displayed by characters or symbols as needed.
[0013]
Acrylic (PMMA), polycarbonate, polystyrene (PS), AS (acrylonitrile citylene copolymer), or the like can be used as a resin for forming the translucent resin portion 2. Among these, acrylic (PMMA) and polycarbonate having high light transmittance and refractive index are desirable. A diffusing agent can be added to the translucent resin portion in order to perform uniform light emission. However, in order to keep the luminance high, it is desirable to use a diffusing agent composed of molecules smaller than the wavelength of the light from the light source. As the diffusing agent, those commonly used such as those containing aluminum oxide, calcium carbonate and the like can be used.
[0014]
ABS, PE, PS, PP, PA, POM, and the like can be used as the resin forming the light-shielding resin portion. Of these, ABS and PS, which have good moldability and good dimensional accuracy during molding, are desirable. The color of the light-shielding resin portion is determined as appropriate according to the application, but in general, it prevents light from leaking to the adjacent light-transmitting resin portion or transmits light when exposed to the display panel. It is desirable that the color be black so that light emission from the conductive resin portion can be reduced.
[0015]
An air layer is formed between the light transmitting resin part and the light shielding resin part surrounding the light transmitting resin part. This air layer can be formed by preventing the two types of resins from completely welding during two-color molding. The larger the area of the air layer that is obtained without causing the welding between the light-transmitting resin portion and the light-shielding resin portion, the more advantageous in obtaining high luminance.
[0016]
FIG. 3 is a diagram illustrating an effect when an air layer is formed between the light-transmitting resin portion and the light-shielding resin portion. FIG. 3 shows a vertical cross section of the resin translucent display 1, the light source 4, and the display panel 5 shown in FIG. The light emitted from the light source 40 and incident on the columnar body 20 from the end face of the columnar body 20 is smaller than the critical angle determined by the refractive index of the columnar body 20 with respect to the air layer C as shown in the enlarged section A in FIG. When the light reaches the side surface of the columnar body 20 at the incident angle θ, the light is totally reflected by the side surface and is reflected while maintaining almost all the light amount. The light from the light source 40 reaches the eyes along the optical path indicated by the arrow K1 in the figure and is visually recognized. Therefore, light from the light source can be visually recognized as high luminance in a wide range corresponding to the critical angle around the resin-made translucent display.
[0017]
On the other hand, if the light-transmitting resin portion and the light-shielding resin portion are integrally connected, high luminance based on such total reflection cannot be obtained. This is because the critical angle of light incident on the columnar body 20 is determined by the translucent resin part and the light-shielding resin part having refractive indexes close to each other, and as a result, an extremely large angle (with respect to the perpendicular to the side surface of the columnar body) (A large angle). That is, as shown in the enlarged view of the portion B in FIG. 4, light emitted from the light source 40 and incident on the columnar body 20a is hardly reflected by the side surface of the columnar body 20a and is absorbed as heat (in FIG. 4, FIG. The parts corresponding to the parts shown are indicated by the same numbers as those in FIG. As a result, it is difficult to directly visually recognize the light from the light source 40 only in a narrow range of the angle α indicated by the one-dot chain line in FIG. In order to cope with this, it is necessary to roughen the upper surface of the columnar body 20a to widen the viewing angle by irregular reflection, but this does not provide high brightness.
[0018]
The following method can be used to form an air layer between the light-transmitting resin portion and the light-shielding resin portion.
[0019]
First, one of two resin portions, a light-shielding resin portion and a light-transmitting resin portion, is molded (primary molding). For this, injection molding is advantageous in terms of cost and time required for molding. However, compression molding can also be used. In addition, it is desirable that the light-shielding resin portion is primarily formed from the viewpoint of the moldability described later and the prevention of welding of the two resins. The secondary molding is performed by injection molding on the other of the two resin portions in a state where the primary molded product is incorporated. That is, a secondary molding die is formed and injection is performed so that a cavity for accommodating the primary molded product is provided in the molding die and the secondary molding is performed so that the final form of the resin-made translucent display body is obtained. Perform molding.
[0020]
In secondary molding, the injection speed is extremely important. The inventor of the present invention has found that if the injection speed is low, the primary molded product and the secondary molded product are welded, and conversely, welding is prevented or reduced by increasing the injection speed higher than the speed at the time of normal injection molding. It has been found that an air layer required for total reflection in the conductive resin portion is formed between both resins. The appropriate value of the injection speed varies depending on the size and number of the secondary molded product, the length and diameter of the runner, the state of the molding die such as the number of gates, the type of resin, the molding temperature, and the like. Whether the injection speed is appropriate or not is determined by preliminary two-color molding and separating the light-transmitting resin part and the light-shielding resin part from the presence or absence of the welding spot and the size of the area. can do.
[0021]
In addition, it is advantageous to select resins that are difficult to weld to each other as the resins for the primary molding and the secondary molding. For this purpose, for example, the primary molding can be performed with a crystalline resin, and the secondary molding can be performed with an amorphous resin. Thus, by adjoining the crystalline and non-crystalline resins, it is possible to reduce the welding of the two resins.
[0022]
Examples of the crystalline resin that can be used here include polyacetal, PP, PE, PA, and examples of the resin that can be used as the non-crystalline resin include polystyrene, PMMA, AS, and ABS.
[0023]
However, by appropriately setting the injection speed, the primary molding can be performed with an amorphous resin and the secondary molding can be performed with a crystalline resin.
[0024]
In order to prevent or reduce the welding of the primary and secondary molding resins, it is also advantageous to make the primary molding resin have a higher glass transition temperature than the secondary molding resin. Thereby, the secondary molding can be performed at a temperature lower than or slightly higher than the glass transition temperature of the primary molding resin, and the melting of the primary molding resin can be prevented or reduced.
[0025]
The following is an example of a desirable combination of resins in the case of using a light-shielding resin [black] for the primary molding resin and a translucent resin [transparent or milky white (by roughing the top surface)] for the secondary molding resin. I do.
Primary molding resin Secondary molding resin
(Light-shielding resin) (Translucent resin)
Polyacetal polystyrene polyethylene polystyrene polypropylene polystyrene polyamide 6,66 polystyrene polyacetal polycarbonate polyacetal acrylic (PMMA)
Polyacetal AS
Polyacetal ABS
Polypropylene Polycarbonate polyethylene Polycarbonate polyethylene Acrylic (PMMA)
Polyethylene AS
Polyethylene ABS
The polyamide 6,66 polycarbonate light-shielding resin portion may be glass-reinforced (reinforced by mixing glass fibers).
[0026]
An example of manufacturing the resin light-transmitting display shown in FIGS. 1 and 2 will be described below. The dimensions of the resin light-transmitting display body shown in FIG. 2 are as follows.
[0027]
Sw: 1.3 mm
Sd: 3.0 mm
Sh: 15.0 mm
Sf: 2.0mm
Tw: 2.0 mm
Td: 3.0 mm
Th: 15.0 mm
Tf: 2.0 mm
W: 20.0 mm
The primary molding and the secondary molding were performed under the following conditions.
Primary molding:
Resin Polyacetal heating cylinder set temperature 200 ± 60 ° C
Injection speed 21.3mm / sec Secondary molding resin Polystyrene (A & M styrene)
Heating cylinder set temperature 200 ± 60 ° C
Injection speed [resin feed speed in extrusion screw of molding machine] (mm / sec)
(1) 25.5, (2) 34.0, (3) 42.5, (4) 51.0, (5) 59.5, (6) 68.0, (7) 76.5.
When the secondary molding was performed at the various injection speeds described above, the following results were obtained. After molding 10 resin light-transmitting display bodies at each injection speed, the light-transmitting resin and the light-shielding resin were separated, and the ones that had been welded were regarded as defective. there were.
[0028]
(1) 10 pieces, (2) 10 pieces, (3) 9 pieces, (4) 6 pieces, (5) 5 pieces, (6) 2 pieces, and (7) 0 pieces. As shown in FIGS. 1 and 2, the light display body is provided with a flange 21 for connecting the columnar body 20 about 6 mm below the top surface of the columnar body, so that the columnar body is viewed from the side opposite to the flange. In addition, it is possible to prevent the luminance from being reduced by the flange portion. The degree of lowering of the flange from the top surface of the columnar body is desirably about 2 to 3 times the depth dimension (Td) of the columnar body from the viewpoint of preventing a reduction in luminance and supporting strength of the columnar body. FIG. 3 shows an optical path K1 in which light totally reflected in the columnar body reaches the eyes without being disturbed by the flange when the columnar body is viewed from the side opposite to the flange. On the other hand, FIG. 4 shows a case where the flange is provided near the top of the columnar body (directly below the display panel). Here, the light that is reflected on the side surface of the columnar body and should reach the eye via the optical path k1 ′ without the flange does not reach the eye as a result of being blocked by the flange. Therefore, when viewed from this direction, the brightness of the resin light-transmitting display body appears to be reduced.
[0029]
In the above example, the columnar body has a vertically long rectangular parallelepiped shape, but the present invention is not limited to this, and various cross-sectional shapes such as a circle, an ellipse, and a polygon can be used. In addition, although six pillars are shown as being arranged in parallel, a plurality of other pillars may be arranged in parallel or a single pillar may be used. The columnar body can be colored while maintaining translucency in addition to being transparent. In any case, the top surface can be a smooth surface or a rough surface.
[0030]
【The invention's effect】
According to the present invention, since the air layer is formed between the resin part formed by the primary molding and the resin part formed by the secondary molding, a part of the light incident from one end of the translucent resin is At the other end and exit from the other end. Therefore, light from the light source can be visually recognized with high luminance in a wide range corresponding to the critical angle of the translucent resin around the translucent display body made of resin.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a state before assembling a resin light-transmitting display body and another member according to an embodiment of the present invention.
FIG. 2 is an exploded perspective view showing the resin light-transmitting display body shown in FIG.
FIG. 3 is a longitudinal sectional view of the resin light-transmitting display body shown in FIG.
FIG. 4 is a longitudinal sectional view of an example of a conventional resin light-transmitting display.
[Explanation of symbols]
1: translucent display body made of resin, 2: translucent resin section, 3: light-shielding resin section, 4: light source section, 5: display panel, 20: columnar body, 21: flange, 40: light source

Claims (3)

In a method of light-transmitting resin part is prepared by two-color molding method of resin-made translucent display body transparent portion of the pillar is formed for passing the light from the enclosed with the back of the light source by the light shielding resin portion So,
One of the two resin portions, the light-shielding resin portion and the light-transmitting resin portion, is first molded, and the other resin portion is secondarily molded by injection molding incorporating the primary molded resin portion,
In performing the secondary molding, the injection speed at the time of the secondary molding is increased so that an air layer is formed between the light-shielding resin portion and the light-transmitting resin portion without welding. A method for manufacturing a light-transmitting display body. A light-shielding resin made of a crystalline resin material is injection-molded to first form the light-shielding resin portion, and a non-crystalline resin is formed in a state where the light-shielding resin portion that has been primarily molded is incorporated into a mold. The method for manufacturing a resin-made light- transmitting display body according to claim 1, wherein the light-transmitting resin portion is formed by injection molding a light- transmitting resin made of a material. The light-shielding resin portion made of an amorphous resin material is injection-molded to form the light-shielding resin portion in a first molding process. The method for manufacturing a resin-made light-transmitting display body according to claim 1, wherein the light-transmitting resin portion is formed by injection molding a light-transmitting resin made of a material.

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