JPH09265806A - Lamp with phase conversion plate and traffic signal using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a traffic signal preventing random refection of sun light and using a lamp with its good visibnility by arranging a phase conversion plate on which a polarizing plate and a 1/4 phase differential plate are laminated with the phase differential plate on the lamp side. SOLUTION: A 1/4 phase differential plate used for a traffic signal is used as the one being optically transparent, having a phase difference equivalent to 1/4 wavelength to the wavelength of sunlight. The 1/4 phase differential plate preferably has a wide-band characteristics showing a 1/4 phase differential in a visible area. As a polarizing plate, generally an iodate polarizing plate of which iodate is adsorbed to poly-vinyl alcohol film, a dye polarizing plate of which dual-color dye is adsorbed to polyvinyl alcohol film or polyester film, or polyethylene polarizing plate is used. A phase conversion plate made of a laminate of the polarizing plate and the 1/4 phase differential plate is arranged on the front face of the lamp by placing the phase differential plate on the lamp side. These are generally used by adhering them to a transparent support plate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lamp having a phase converter on the front surface thereof and a traffic signal using the lamp.

[0002]

2. Description of the Related Art Traffic lights installed at roadsides have high emission brightness and are easy to see. However, when sunlight shines on the front of the traffic light, it is reflected on the front of the traffic light and the lights of the traffic lights are off. May also appear to be lit due to sunlight reflections. In order to avoid this, a sunshade is provided above the traffic signal to avoid sunlight irradiation.

[0003]

However, even if a sunshade is provided above the traffic light, the sunbeams illuminate the traffic light from a low angle in the strong evening of the west, and the traffic signal lights up or goes out. Very hard to confirm.

As a result of intensive studies for solving the above problems, the inventors of the present invention have used a lamp having a phase conversion plate formed by laminating a polarizing plate and a 1/4 retardation plate on a front surface for a traffic signal. The present invention has been found out that it is possible to prevent irregular reflection of sunlight and provide a traffic signal with good visibility.

[0005]

That is, the present invention is characterized in that a phase conversion plate formed by laminating a polarizing plate and a 1/4 phase difference plate is arranged in front of the lamp with the phase difference plate facing the lamp. A lamp with a phase conversion plate and a traffic signal equipped with this lamp. Hereinafter, the present invention will be described in detail.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The 1/4 retardation plate used in the present invention is an optically transparent one having a retardation equivalent to 1/4 wavelength with respect to the wavelength of sunlight. For example, 2
Examples thereof include cellulose films such as cellulose acetate, polycarbonate films, polyester films such as polyethylene terephthalate, acrylic films such as polymethylmethacrylate, olefin films such as polystyrene and polyethylene. A polycarbonate film and a cellulose film are preferable in terms of optical transparency, heat resistance, stretchability, and the like. In particular, when heat resistance is required, a film made of engineering plastic such as polysulfone, polyether sulfone, polyether ether ketone, and polyarylate can be used.

The 1/4 phase difference plate is 1 in the visible light region.
A wide band characteristic exhibiting a / 4 phase difference is preferable. As a method for producing a retardation plate exhibiting broadband characteristics, for example, a polycarbonate film retardation plate and a polypropylene film retardation plate laminated such that the optical axis is orthogonal, a polycarbonate film retardation plate and Polyvinyl alcohol film retardation plates laminated so that their optical axes are orthogonal to each other, Polyethersulfone film retardation plates and polycarbonate film retardation plates are laminated such that their optical axes are orthogonal to each other, and polysulfone Laminated a retardation film of a polyester film and a retardation film of a polyester film so that the optical axes are orthogonal, so that the optical axes of the retardation plate of a polyarylate film and the polyester film are orthogonal to each other. Laminated film, cellulose acetate film retarder and polycarbonate film Optical axis phase difference plate there is such a laminate of in parallel.

The polarizing plate is usually an iodine-based polarizing plate in which iodine is adsorbed and oriented on a polyvinyl alcohol-based film, and a dichroic dye is adsorbed on a polyvinyl alcohol-based film.
Alternatively, a dye-based polarizing plate, a polyene-based polarizing plate or the like that is adsorbed and oriented on a polyester film is used. For outdoor use, a dye-based polarizing plate is preferable because it is excellent in durability and light resistance.

The phase conversion plate formed by laminating the polarizing plate and the 1/4 phase difference plate is arranged in front of the lamp with the phase difference plate facing the lamp.

A phase conversion plate formed by laminating a polarizing plate and a 1/4 retardation plate can be used as it is, but it is usually used by being attached to a transparent support plate. Examples of the transparent support plate include a plastic plate such as a polycarbonate plate and an acrylic plate such as a polymethylmethacrylate plate, and a glass plate. The thickness of the transparent support plate is 0.5 mm to 50 m
m, preferably 1 mm to 10 mm. The transparent support plate is usually attached to the polarizing plate side of the phase conversion plate in order to protect the polarizing plate and the retardation plate, but it may be attached to the retardation plate side for use. That is, it is arranged on the front surface of the lamp with the following configuration. (1) Transparent support plate / phase conversion plate (polarizing plate / phase difference plate) /
Lamp (2) Phase conversion plate (polarizing plate / phase difference plate) / transparent support plate /
lamp

The surface of the polarizing plate of the outermost transparent support plate or the phase conversion plate is preferably subjected to antireflection treatment or low reflection treatment, and more preferably to stain prevention treatment.

[0012]

EFFECT OF THE INVENTION The lamp with a phase conversion plate of the present invention prevents diffused reflection of sunlight and has good visibility, and when used in a traffic signal, its effect is great.

[0013]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the examples.
The retardation was measured with a Senarmont polarization microscope.

Example 1 A cellulose acetate film having a thickness of 190 μm,
Sumitomo Chemical Co., Ltd. iodine-based polarizing plate SH1832 on one side of a quarter retardation plate having a retardation of 135 nm.
A was laminated via an adhesive, and a polycarbonate plate having a thickness of 5 mm was attached to the polarizing plate side as a transparent support plate to manufacture a phase conversion plate. Next, a lamp having the phase difference plate on the lamp side and the phase conversion plate arranged on the front surface of the lamp was manufactured, and this was attached to the lighting part of the traffic signal, and a confirmation test of lighting display or extinguishing display was performed. As a result, sunlight reflection was suppressed and visibility was good.

Example 2 As a polarizing plate, a dye type polarizing plate ST18 manufactured by Sumitomo Chemical Co., Ltd.
Example 1 was repeated except that 22A was used. As a result of the confirmation test of the traffic signal on / off display, the sunlight reflection was suppressed and the visibility was good.

Example 3 A polycarbonate film having a thickness of 100 μm was used,
A retardation plate having a retardation of 405.3 nm and a polyvinyl alcohol film having a thickness of 21 μm,
Example 1 except that retardation plates having a retardation of 552.8 nm were laminated so that the optical axes were orthogonal to each other, and dye-based polarizing plate ST1822A manufactured by Sumitomo Chemical Co., Ltd. was laminated on one surface thereof via an adhesive. It carried out similarly to. As a result of the confirmation test of the traffic signal on / off display, the sunlight reflection was suppressed and the visibility was good.

Example 4 A retardation plate made of a polyarylate film having a thickness of 100 μm and having a retardation of 906.5 nm and a polyethylene terephthalate film having a thickness of 100 μm and having a retardation of 1054 nm were used. The same procedure as in Example 3 was carried out except that the layers were laminated so that the optical axes were orthogonal to each other. As a result of the confirmation test of the traffic signal on / off display, the sunlight reflection was suppressed and the visibility was good.

Example 5 A retardation plate made of a polysulfone film having a thickness of 100 μm and having a retardation of 503.6 nm and a polyethylene terephthalate film having a thickness of 100 μm and having a retardation of 651.1 nm. Was performed in the same manner as in Example 3 except that the layers were laminated so that the optical axes thereof were orthogonal to each other. As a result of the confirmation test of the traffic signal on / off display, the sunlight reflection was suppressed and the visibility was good.

Claims (6)

[Claims] 1. A lamp with a phase conversion plate, wherein a phase conversion plate formed by laminating a polarizing plate and a 1/4 phase difference plate is arranged in front of the lamp with the phase difference plate facing the lamp. 2. A phase conversion plate formed by laminating a polarizing plate and a 1/4 retardation plate, and further laminating a transparent support plate, and arranging the retardation plate from the polarizing plate on the lamp side in front of the lamp. A lamp with a phase conversion plate. 3. The lamp with a phase conversion plate according to claim 1, wherein the 1/4 phase difference plate is a phase difference plate having a wide band characteristic. 4. The 1/4 retardation plate is formed by laminating a polycarbonate film retardation plate and a polyvinyl alcohol film retardation plate so that their optical axes are orthogonal to each other. The lamp with a phase conversion plate described in 3. 5. The lamp with a phase conversion plate according to claim 1, wherein the dichroic dye used for the polarizing plate is a dye. 6. A traffic signal including the lamp with a phase conversion plate according to claim 1 or 2.