JPH07322943A - Transparent board - Google Patents

Abstract

PURPOSE:To improve the transmission factor of a transparent board while avoiding the cost increase. CONSTITUTION:A heat ray reflecting film 4 provided with a conducting selective transmission reflecting layer 9 made of a thin film of a metal and/or a metal oxide film and having the electric resistance inversely proportional to the transmission factor of the visible light is stuck all over the surface, the portion of the selective transmission reflecting layer 9 having the electric resistance inversely proportional to the transmission factor is used, and a transparent board 2 having a high transmission factor is provided with no cost increase.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a see-through plate, and more particularly to a transparent plate having a heat ray reflective film attached to one surface thereof.

[0002]

2. Description of the Related Art For example, Japanese Utility Model Laid-Open No. 54985 / F25D23 /
02) is provided with a see-through plate on the back surface of which a vapor deposition layer made of a conductive metal and having a selective transmission / reflection function is provided, and a plurality of slits are alternately provided at the vapor deposition layer. There is disclosed a refrigeration showcase in which the vapor-deposited layer is an electric heating element and a see-through plate in which the electric resistance in the vapor-deposited layer is increased by the slit is provided.

[0003]

In the above conventional technique, since the slit is formed by a cutter or the like, the opposing slit edges are extremely close to or in contact with each other. Not only is there a problem in terms of safety, but there is also a problem in that it takes time and labor for processing to form the slits, resulting in an increase in cost.

[0004]

In order to solve the above-mentioned problems, the present invention comprises a metal or a thin film of a metal oxide film, and an electrically conductive selective transmission / reflection layer 9 whose electric resistance is inversely proportional to the transmittance of visible light. Provided is a transparent plate 2 having a heat ray reflective film 4 having the above attached on one surface.

[0005]

The heat ray reflecting film 4 has a function of reflecting the heat ray transmitted through the transparent plate 2 to the outside by itself, and also has a function of heating the transparent plate 2 as a surface heater when energized. In addition, by using a portion where the electric resistance of the selective transmission reflection layer 9 itself of the heat ray reflection film 4 is inversely proportional to the transmittance of visible light, without increasing the cost,
It becomes possible to increase the transmittance.

[0006]

Embodiments of the present invention will now be described in detail with reference to the drawings. 1 and 2 are, for example, a low-temperature showcase, that is, a see-through plate that is used for windows and doors that cover the opening of a freezer showcase or a refrigerated showcase and separates the inside and the outside of the showcase. The transparent plates 2 and 3 made of a plurality of transparent glasses or transparent plastic plates, the heat ray reflection film 4 attached to the transparent plate 2 on the outside of the inside of the transparent plate, and the space. An annular metal frame 6 for covering the outer periphery of the spacer interposed between the transparent plates 2 and 3 for maintaining, and a dew-proof electric heater 7 annularly arranged along the inner surface of the metal frame. Has been done.

As shown in the circle P in FIG. 2, the heat ray reflective film has a selective transmission / reflection layer 9 in which thin films of metal and / or metal oxide are laminated, and a glue layer 10 made of a transparent adhesive.
It has a function of transmitting visible light and reflecting heat rays such as infrared rays. The selective transmission / reflection layer 9 is made of a metal and / or a metal oxide, has a function as a dielectric, and generates heat when energized. Therefore, the pair of parallel electrodes 11 and 12 are formed at both ends of the heat ray reflective film. Provided and connected in series with the electric heater 7 to connect to 100V
Connected to the commercial power supply 13 of. The selective reflection / transmission layer 9 acts as a surface heater by being energized,
Its electric resistance is 1 when the visible light transmittance is 80%.
In the case of 0 Ω / cm 2 and 60%, it becomes 15 Ω / cm 2, which is inversely proportional to the transmittance of visible light, that is, the electrical resistance of the selective transmission / reflection layer 9 is small when the transmittance of visible light is high, and is large when it is low. The inventors of the present application found out by experimentation that there is a relationship.

Here, the transmittance is the transmittance of the selective transmission layer 9 itself. Since the selective transmission / transmission layer itself is thin and soft, for example, the selective transmission / reflection layer is attached to a transparent plate of glass to measure the transmittance. However, the transmittance of glass itself is 10
The measured transmittance, not 0%, is not the true transmittance of the selective transmission / transmissive layer itself because it was measured by attaching the selective transmission / transmissive layer to glass. Further, the transmittance of the glass itself is different depending on the wavelength (μm) of the light ray in the range visible to human eyes (range of visible light ray). Therefore, in order to obtain the transmittance of the selective transmission / transmissive layer itself, it is necessary to correct the value obtained by adhering the selective transmission / transmissive layer to glass and measuring it by taking the transmittance of glass into consideration. Therefore, in the present invention, a value obtained by sticking a selective transmission / transmissive layer to glass and measuring the transmittance is corrected by adding the transmittance of the glass, and as described above, the electrical resistance of the selective transmission / transmissive layer itself is: They have discovered that there is a portion that is inversely proportional to the visible light transmittance of the selective transmission / reflection layer.
Further, in the present invention, the use of the above-mentioned inversely proportional portion makes it possible to increase the transmittance without increasing the cost.

For this reason, in order to see through the interior of the see-through plate 1 used in a freezing / refrigerating showcase, it is necessary to use a heat ray reflective film 4 having a high visible light transmittance, that is, a low electric resistance. is there. Therefore, in order to use the selective transmission / reflection layer 9 of the heat ray reflection film 4 as a surface heater, the voltage of the commercial power supply 13 is high, and therefore the electric heater 7 for heating the metal frame 6 is connected in series to the selective transmission / reflection layer 9. Thus, the commercial power source is divided in proportion to the resistance of both of them, and the electric heater 7 also functions as a transformer. In the single transparent plate 1, the selective transmission / reflection layer 9 and the electric heater 7 have, for example, a voltage between terminals of 25 V, a resistance of 25 Ω, and a power consumption of 2.
In the case of 5 W, the required voltage for series connection is 50 V. In this case, when using the commercial power supply 13, it is preferable to provide a diode D as shown by the chain line in FIG.

The metal and / or metal oxide (hereinafter abbreviated as a metal layer) is one or more metal thin films selected from the group consisting of gold, silver, copper, palladium and aluminum and / or In2O3, SuO2. , An oxide thin film of CdSnO4 or the like, and is formed on the surface of a transparent plastic film or on an anchor coat layer of about 2 μm or less made of, for example, a silicon-based or titanium-based organometallic compound provided on the surface. . Further, a high-refractive-index dielectric layer (to be referred to as a dielectric layer hereinafter) formed on plastic and having a thickness of 50 to 4000 angstrom is formed. The metal layer has a refractive index of 1.8 or more, for example, titanium dioxide, tin oxide, indium oxide or the like and has a film thickness of 50 to 6
It may be a structure sandwiched between 00 dielectric layers. In addition, the metal layer or the dielectric layer can be protected by an organic or inorganic layer such as an acrylic resin, a polyester resin, or a silicone resin in order to improve mechanical durability, and a transparent heat insulating layer. May be laminated.

Examples of the transparent plastic film serving as the base layer on which the thin film is formed include polyester resins such as polyethylene terephthalate, polyethylene-2.6-naphthalate and polybutylene terephthalate, polycarbonate resins, polyketones, polyethylene and polypropylene. Polyolefin resin, polyvinyl chloride, polystyrene polyphenylene oxide, polymethylmethacrylate, polystyrene, etc. or polyamide resin, polyimide resin, cellophane, cellulose resin film or sheet of cellulose triacetate, etc. are used.

FIG. 3 shows a freezing showcase 20 having two see-through plates 1, and FIG. 4 shows electrical connection of the see-through plate 1. As shown in FIG. 4, with respect to the commercial power source 13, each electric heater 7,
7 and the selective transmission / reflection layers 9 and 9 are connected in series. In this case, the applied voltage of 100 V is divided into four in proportion to the resistance of each electric heater and the selective transmission / reflection layer. According to the above-mentioned structure, the heat ray reflective film 4 reflects the heat ray transmitted through the transparent plate 2 toward the outside of the low temperature showcase with the selective transmission / reflection layer 7 to raise the temperature of the transparent plate 2 to increase the temperature outside the refrigerator. On the other hand, when the selective transmission / reflection layer 9 is energized, it acts as a surface heater to heat the transparent plate 2, and by both of these actions, condensation on the surface of the transparent plate 2 can be prevented. By connecting the selective transmission / reflection layer 9 and the electric heater 7 or the selective transmission / reflection layers 9, 9 to each other, the applied voltage can be divided in proportion to its resistance and the other can act as a voltage divider. Therefore, the selective transmission / reflection layer 9 having a low electric resistance and a high transmittance can be used, and the heat ray reflection film having the selective transmission / reflection layer is used while ensuring the transmittance of the see-through plate 2. Prevents condensation

Further, there is a portion where the electric resistance of the selective transmission / reflection layer 9 itself is inversely proportional to the visible light transmittance of the selective transmission / reflection layer 9. Therefore, the selective transmission / reflection layer 9 should use the above-mentioned inversely proportional portion. Thus, the transmittance can be increased without increasing the cost.

[0014]

According to the present invention described above, a heat ray reflective film, which is made of a thin film of metal or a metal oxide film and has an electrically conductive selective transmission reflection layer whose electric resistance is inversely proportional to the transmittance of visible light, is attached to one surface. And a transparent plate comprising a transparent plate and an electric heater connected in series with the selective transmission reflective layer of the heat ray reflective film, the electrical resistance of the selective transmission reflective layer itself, the selective transmission reflective layer Therefore, the selective transmission reflection layer of the present invention can increase the transmittance without increasing the cost by using the above-mentioned inversely proportional portion.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a see-through plate showing an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a front view of a frozen showcase showing an embodiment of the present invention.

FIG. 4 is an electrical connection diagram of a see-through plate in the refrigerating showcase of FIG.

[Explanation of symbols]

 2 transparent plate 4 heat ray reflection film 7 electric heater 9 selective transmission reflection layer

Claims (1)

[Claims] 1. A transparent plate comprising a thin film of a metal or a metal oxide film, and a heat ray reflective film having an electrically conductive selective transmission / reflection layer whose electrical resistance is inversely proportional to the transmittance of visible light and which is adhered on one surface.