JP4771706B2 - Backlight for electric signboard, and electric signboard using the same - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a backlight for an electric signboard and an electric signboard using the same, and relates to a backlight that is thin while being for both sides.

  2. Description of the Related Art Conventionally, an electric signboard that illuminates and displays an image layer on which an image is printed or the like is arranged above a fluorescent lamp by arranging several fluorescent lamps in a housing, for example, as shown in FIG. It is structured to illuminate the image layer.

  In order to prevent the shape of the fluorescent lamp from popping up, the electric signboard having such a structure needs to have a distance of about 15 to 20 cm between the fluorescent lamp and the image layer, which increases the thickness. There are drawbacks. In particular, in recent years, it may be required to observe images from both sides, and when the distance between the fluorescent lamp and the image layers on both sides is increased, the thickness becomes even thicker.

  Therefore, the image can be observed from both sides, and as a solution to reducing the thickness, the light guide plates are back to back as shown in FIG. There has been proposed an electric signboard using a backlight in which a light source is arranged on a side end portion of a light guide plate (Patent Document 1). Since this electric signboard can arrange | position a light source in a side edge part, thickness can be made thinner than the conventional electric signboard.

Japanese Patent Laying-Open No. 2004-13072 (Claims, FIG. 3)

  However, such an electric signboard of Patent Document 1 is also thick, and an electric signboard with a further reduced thickness has been demanded.

The electrical signboard of the present invention that solves the above-described problems has at least one side end as a light incident surface, and both sides substantially orthogonal to the light exit surface as JIS K7136: 2000 haze of 10 to 40 % Light guide plate, a light diffusive sheet having a haze of 70% or more according to JIS K7136: 2000, which is disposed so as to be in contact with both sides of the light guide plate, and at least one side end portion of the light guide plate The backlight is composed of a light source disposed in the light source, and image layers are disposed on both sides of the backlight.

  The backlight for an electric signboard according to the present invention uses a light guide plate having a light emitting surface on both sides and having a haze (JIS K7136: 2000) of 2% or more. The thickness when used as a decorative signboard can be reduced. In particular, the thickness of the light guide plate is reduced by setting the light guide plate to have a haze of 10 to 40% and a light diffusing sheet having a haze of 70% or more on both sides of the light guide plate. However, the overall luminance can be increased uniformly. Moreover, the electric signboard of the present invention using the backlight for the electric signboard of the present invention can be made extremely thin.

  First, the backlight for an electric signboard of the present invention will be described.

  The backlight for an electric signboard according to the present invention has at least one side end as a light incident surface and light exit surfaces on both sides substantially perpendicular to the light incident surface, and the haze (JIS K7136: 2000) is 2% or more. It comprises a light guide plate and a light source disposed at at least one side end of the light guide plate. Hereinafter, an embodiment of the backlight for an electric signboard of the present invention will be described.

  1 and 2 are sectional views showing an embodiment of a backlight 1 for an electric signboard according to the present invention. 1 includes a light guide plate 11, a light source 12, a reflective film 13, and a reflective tape 14, and the electrical signboard backlight 1 of FIG. 2 further includes a light diffusing sheet 15. Yes.

  The light guide plate has a haze (JIS K7136: 2000) of 2% or more, preferably 10% or more, with at least one side end as a light incident surface and both sides substantially orthogonal to the light emitting surface as light emission surfaces. Is used.

  Such a light guide plate having a uniform haze of 2% or more as a whole can emit light from both sides, so that the image layers on both sides are illuminated only by using one light guide plate that causes the thickness to increase. be able to. Therefore, the backlight for an electric signboard of the present invention using such a light guide plate can make the thickness of the electric signboard extremely thin.

  On the other hand, the light guide plate used for the conventional electric signboard has a diffuse reflection pattern on the back surface of the light guide plate, and requires a reflective film on the back surface of the light guide plate. Therefore, when it is intended to illuminate the image layers on both sides, the light guide plates must be back to back and a reflective film must be sandwiched between the light guide plates, and the thickness of the electric signboard cannot be made sufficiently thin.

  The light guide plate constituting the backlight for the electric signboard of the present invention can be obtained by kneading a light diffusing agent in a transparent resin and molding it into a substantially flat plate shape.

  Transparent resins include polyester resins, acrylic resins, acrylic urethane resins, polyester acrylate resins, polyurethane acrylate resins, epoxy acrylate resins, urethane resins, epoxy resins, polycarbonate resins, cellulose resins, and acetals. Resin, polyethylene resin, polystyrene resin, polyamide resin, polyimide resin, melamine resin, phenol resin, silicone resin and other thermoplastic resins, thermosetting resins, ionizing radiation curable resins, etc. . Among these, acrylic resins having excellent optical properties are preferably used, and among them, polymethyl methacrylate resin is particularly preferable.

  As light diffusing agents, inorganic fine particles such as calcium carbonate, magnesium carbonate, barium sulfate, silica, aluminum hydroxide, kaolin, clay, talc, acrylic resin particles, silicone resin particles, polystyrene resin particles, polyurethane resin particles, polyethylene resin Examples thereof include organic fine particles such as particles, benzoguanamine resin particles, and epoxy resin particles.

  The reason why the haze of the light guide plate is set to 2% or more is to sufficiently emit light from the light exit surface side of the light guide plate to obtain sufficient brightness when used as an electric decoration signboard. It should be noted that the haze of the light guide plate can be made higher so that the light emitted from the light exit surface can be made more sufficient and the information on the front and back image layers can be prevented from intermingling. It is preferable in terms of obtaining concealability. However, in the electric signboard using the light guide plate, it is required to provide the light source only on one side of the light guide plate due to the problem of installation occupation area and cost. Thus, when the light source is provided only on one side of the light guide plate, if the haze of the light guide plate is increased too much, a luminance difference occurs such that the luminance on the light source side is large but the luminance on the side away from the light source is small. It becomes like this. Therefore, as a result of further investigation, the present inventors have made a light diffusive sheet having a haze of 70% or more in contact with both sides of the light guide plate having a haze of 10 to 40%, preferably 20 to 40%. By arranging it, the overall brightness of the illuminated signboard is sufficient, there is almost no difference in brightness due to the distance from the light source, and the backlight for the illuminated signboard that can prevent the crossing of information on the front and back has been completed. .

The haze of the light guide plate can be adjusted by the thickness of the light guide plate and the amount of light diffusing agent added in the light guide plate. For example, in order to set the haze to 10 to 40%, the thickness of the light guide plate is 2 to 20 mm, and the light diffusing agent is contained in an amount of 0.5 × 10 ^{−5 to} 0.1 parts by weight with respect to 100 parts by weight of the transparent resin. Just do it.

  Examples of the light diffusing sheet include those in which a light diffusing layer comprising a transparent binder resin and a light diffusing agent is provided on one or both surfaces of a transparent substrate, and those in which one or both surfaces of a transparent substrate are sandblasted.

  Examples of the transparent substrate include various synthetic resin films composed of polyethylene terephthalate, polycarbonate, polypropylene, polyethylene, polyvinyl chloride, polyethylene naphthalate, polystyrene, (meth) acrylate resin, fluorine resin, and the like. The thickness of the transparent substrate is about 10 to 200 μm. As the transparent binder resin and light diffusing agent of the light diffusion layer, the above-described transparent resin and light diffusing agent can be used.

  The reason why the haze of the light diffusing sheet is set to 70% or more is to increase the luminance of the backlight uniformly as a whole and to prevent the information on the image layers on the front and back sides from being mixed when used as an electric decoration signboard. . In addition, since luminance may be impaired when the haze is extremely high, the upper limit of haze is preferably 99% or less.

  The haze of the light diffusing sheet can be adjusted by the thickness of the light diffusing layer and the content of the light diffusing agent in the light diffusing layer. In order to make the haze 70% or more, the thickness of the light diffusion layer is 5 to 50 μm, and the content of the light diffusing agent in the light diffusion layer is 50 to 300 parts by weight with respect to 100 parts by weight of the binder resin. Good.

  The light diffusing sheet is arranged so as to be in contact with both surfaces of the light guide plate. They may be placed on the light guide plate, or may be bonded together with an adhesive.

  The light source is disposed on at least one side end of the light guide plate. As the light source, a fluorescent lamp, a cold cathode tube, and an LED are used. Examples of the shape of the light source include a linear shape, a U shape, and a dot shape.

  In order to prevent leakage of light, it is preferable to attach a reflective tape 14 to the side end portion of the light guide plate 11 where the light source 12 is not disposed (FIGS. 1 and 2). Further, it is preferable to wind a reflection 13 film around the light source 12 except for the light guide plate 11 side so that light is efficiently incident on the light guide plate 11 (FIGS. 1 and 2).

  Next, the electric signboard of the present invention will be described.

  The electric signboard of the present invention is an electric signboard comprising a backlight and image layers disposed on both sides of the backlight, and the backlight of the present invention described above is used as the backlight. It is characterized by this. Hereinafter, embodiments of the electric signboard of the present invention will be described.

  FIG. 3 is a cross-sectional view showing an embodiment of the electric signboard 2 of the present invention. The electric signboard 2 includes an electric signboard backlight including a light guide plate 11, a light source 12, a reflective film 13, a reflective tape 14, and a light diffusing sheet 15, an image layer 21, an acrylic plate 22, and a storage box 23. ing.

  As the backlight for the electric signboard, the backlight of the present invention described above can be used.

  The image layer is formed by printing or pasting a cutting sheet on a transparent or translucent film or sheet. Further, the image layer may be formed by printing directly on the light diffusive sheet or pasting a cutting sheet.

  The storage box is for storing a light source and is made of various metals having light blocking properties. Moreover, in order to fix other members, such as a light source, a light-guide plate, an image layer, and an acrylic board, it is preferable to provide fixing means, such as a screw, in these storage boxes.

  The acrylic plate is for protecting the image layer, and a commercially available acrylic plate can be used.

  The electric signboard described above can be installed at an installation location such as a ceiling using a fixture such as a screw.

  The following examples further illustrate the present invention. “Parts” and “%” are based on weight unless otherwise specified.

[ Reference Example 1]
After mixing 0.02 part of acrylic resin particles (MBX-5: Sekisui Plastics Co., Ltd.) with 100 parts of aromatic polycarbonate resin (Panlite L-1225: Teijin Chemicals, ηSP = 0.41), screw Melted and kneaded at a cylinder temperature of 280 ° C. with a vented single screw extruder (VSK-30: Nakatani Co., Ltd.) with a diameter of 30 mm to obtain pellets by strand cutting. The obtained pellets were heated at 120 ° C. for 5 hours with a hot air circulation dryer. After drying, it was molded by an injection molding machine at a cylinder temperature of 280 ° C. and a mold temperature of 80 ° C. to obtain a light guide plate having a width of 1800 mm, a height of 330 mm, and a thickness of 4 mm. The haze of the obtained light guide plate was 28.9%.

Next, a cold cathode tube is arranged at one side end of the light guide plate on the wide side, and the side end portion other than the light incident surface of the light guide plate is covered with a reflective tape, and the periphery of the cold cathode tube other than the light guide plate side Was covered with a reflective film to obtain a back light for an electric signboard of Reference Example 1.

Next, an image layer formed by forming an image on a transparent film was placed on the obtained backlight for the electrical signboard, and the electrical signboard of Reference Example 1 was obtained.

[ Reference Example 2]
A light diffusing sheet (light up TL4: Kimotosha) with a haze of 46% is directly stacked on both sides of the light guide plate of the backlight for the electric signboard of Reference Example 1, and the back for the electric signboard of Reference Example 2 Got the light.

Next, an image layer formed by forming an image on a transparent film was placed on the obtained backlight for the electrical signboard, and the electrical signboard of Reference Example 2 was obtained.

[Example]
A light diffusing sheet of 88% haze (Light-up MXE: Kimoto Co., thickness 110 μm) is directly laminated on both sides of the light guide plate of the backlight for the electric signboard of Reference Example 1, and the electric signboard of the example. For backlight.

  Next, an image layer formed by forming an image on a transparent film was placed on the obtained backlight for the electrical signboard, and the electrical signboard of Example 3 was obtained.

[ Reference Example 3 ]
A light guide plate was obtained in the same manner as in Reference Example 1 except that 0.05 part of acrylic resin particles was mixed with 100 parts of aromatic polycarbonate resin. The haze of the obtained light guide plate was 46.1%.

Next, one cold-cathode tube is disposed on one side of the wide side of the light guide plate, and the side end of the light guide plate other than the light incident surface is covered with a reflective tape, and other than the light guide plate side of the cold cathode tube Was covered with a reflective film to obtain a backlight for an electric signboard of Reference Example 3 .

Next, an image layer formed by forming an image on a transparent film was placed on the obtained backlight for the electrical signboard, and the electrical signboard of Reference Example 3 was obtained.

The backlights for electric signboards obtained in Reference Examples 1 to 3 and Examples can emit light from both sides with only one light guide plate, and have a thickness as thin as about 4 mm. Moreover, the reference sign examples 1-3 using these backlights for electric signboards and the electric signboards of the examples were thin.

Moreover, the following items were evaluated about the electrical decoration signboards of Reference Examples 1 to 3 and Examples . The results are shown in Table 1.

(1) Concealment of image Visual evaluation was performed on the crossing of the images on the front and back image layers. As a result, “◯” indicates that the images are not mixed, and “Δ” indicates that the images are slightly mixed.

(2) Uniformity of luminance The difference in luminance between the side closer to the light source and the side away from the light source was visually evaluated. As a result, “◯” indicates that the luminance difference is hardly felt, and “Δ” indicates that the luminance difference is slightly felt.

  As is apparent from the results in Table 1, the electric signboards of the examples are arranged so that the light diffusive sheets having a haze of 70% or more are in contact with the surfaces on both sides of the light guide plate having a haze of 10 to 40%. Since the backlight for the electric signboard of the example which is formed is used, both the concealment property of the image and the uniformity of the brightness were satisfactory.

Sectional drawing which shows one Example of the backlight for the electrical signboard of this invention Sectional drawing which shows the other Example of the backlight for the electrical signboards of this invention Sectional drawing which shows one Example of the electrical signboard of this invention Sectional drawing which shows an example of the conventional electrical signboard Sectional drawing which shows the other example of the conventional electrical signboard

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Backlight for electric signboard 11 ... Light guide plate 12 ... Light source 13 ... Reflective film 14 ... Reflective tape 15 ... Light diffusive sheet 2 ... Electric signboard 21 ... Image layer 22 ... Acrylic plate 23 ... Storage box 24 ... Housing

Claims (1)

JIS K7136: 2000 haze of 10 to 40%, and both sides of the light guide plate, wherein at least one side end is a light incident surface, and both sides substantially orthogonal to the light exit surface A backlight composed of a light diffusive sheet having a haze of 70% or more of JIS K7136: 2000 disposed so as to be in contact with the light source, and a light source disposed on at least one side end of the light guide plate ; An electric signboard comprising an image layer disposed on both sides of a backlight.

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