JPS5898701A - Pentagonal roof prism - Google Patents

Abstract

PURPOSE:To obtain a pentagonal roof prism changing hardly the quality of a light image by laminating and fixing a thin film layer with low water absorbency and a heat insulating layer on the rear side of each of the specular planes of a prism body except the plane of light incidence and the plane of light emergence. CONSTITUTION:A prism body 1 formed by injection-molding polymethyl methacrylate or the like has a plane 2 of light incidence on which a light source is incident, 2 specular planes 4, 5 making 90 deg. angle with an edge 3 in-between, a specular plane 6 reflecting images from the planes 4, 5, and a plane 7 of light emergence. Vapor-deposited layers 8 of Al, Ag or the like are formed on the planes 4, 5, 6, and other planes are not optically used. Laminated members 9 are prepared beforehand. The members 9 are laminated and fixed on the rear sides of the planes 4, 5, 6. Each of the members 9 is composed of a metallic thin film layer 10 with low water absorbency, adhesive layers 11, 12 formed on both sides of the layer 10, and a heat insulating member 13 stuck to one adhesive layer 12.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pentagonal roof prism made of plastic.

Conventionally, instead of the Bentagonardano 1 prism made of glass, it has been made of plastic from the viewpoint of reducing weight and improving productivity. Various methods are used to protect the reflective surface of such plastic prisms, one of which is to attach metal foil such as aluminum foil with adhesive to the back side of the reflective surface. Pasting is being done. Although it can be expected that moisture resistance will be improved by such means,
It is not possible to improve both heat resistance and cold resistance, and the reflective surface deforms when the temperature changes, resulting in a disadvantage.

In addition, after depositing A1, A1, etc. on the surface that will become the reflective surface,
A method of painting the molded product black has also been adopted, but this method has disadvantages such as lack of moisture resistance, deterioration of the surface of the molded product due to paint, and the need for complicated work such as masking.

Furthermore, after depositing AJ, AP, etc. on the surface that will become one reflective surface,
There is also a method of re-evaporating substances such as s=o and 5LOs on top of it, but if the film thickness of these vapor-deposited substances is thin, there is no moisture resistance effect, and if the film is thick, the difference in thermal expansion between the prism base material It has the disadvantage of causing cracks and peeling. In addition, there is a method of applying a moisture-resistant paint instead of vapor-depositing a substance such as SLO, but while this has excellent moisture resistance,
It has the disadvantage of not having any heat or cold resistance effects.

As described above, there are various types of conventional reflective surface forming means, but those that are hygroscopic are easily buried, and those that are not resistant to heat and cold tend to cause images to double.

The present invention has been made in consideration of these points, and an object of the present invention is to obtain a pentagonal roof prism which is excellent in moisture resistance, heat resistance and cold resistance, and has little change in optical image quality even when formed of plastics.

In the present invention, a thin film layer with low water absorption and a heat insulating layer are sequentially laminated and fixed on the back side of the reflective surface other than the light entrance surface and the light exit surface of the prism body, so the moisture resistance is improved by the thin film layer. The heat-resistance and cold-resistance are enhanced by the heat-insulating layer located on the outside thereof, thereby eliminating the influence of humidity and temperature changes, so that the optical image quality is less likely to change.

An embodiment of the present invention will be described based on the drawings. First, the prism body (1) is molded from K by injection molding using a material such as methyl methacrylate (MMA). This prism body (1) has a light incident surface (2) on which a light image is incident, and two reflective surfaces (4) (5) formed at an angle of 90FfL with each other across a ridgeline (3). , has a reflective surface (6) that reflects the images from these reflections [m (4) (5), and an output Wi (7). The other surfaces are optically unused surfaces. And the reflective surface (4)
(5) In (6), Aj, A1) type vapor deposited layer (8
) are formed respectively.

Next, the laminated member (9) is prepared in advance and
This laminated member (9) has at least the reflective surface (4) (
5) Laminated and fixed on (6). In this laminated member (9), an adhesive layer α force (2) is formed on the front and back sides between the metal thin film layers, which are thin film layers with low water absorption, and a heat insulating member (to) is bonded to one adhesive layer (6). There is. Such laminated members (
9) is preferably produced in large quantities in advance, and a protective paper (not shown) is adhered to the adhesive layer α1) side.

The heat insulating layer may be made of felt, sponge, artificial leather, etc. with a thickness of 1 to 5 cm.

In such a configuration, the reflective surfaces (4) (5) (6
) has an adhesive between the metal thin film layers, so it has extremely high moisture resistance, and there is also a heat insulating layer (
2) is bonded, so it has high heat and cold resistance.

Therefore, disturbances in the optical image due to changes in humidity or temperature are extremely reduced. The effect is particularly remarkable at the ridgeline (3).

Therefore, as the adhesive layer (b), one should be selected that will not alter or deform the prism body (1).
Also, do not use materials that corrode the deposited layer (8). Specifically, it is desirable to use an acrylic adhesive.

In addition, in practice, it is also possible to use a polyester film or the like with low water absorption in place of the metal thin film layer. If this film is made black, it is also possible to omit dot-colored coating to prevent the reflective surface from being irradiated.

The present invention provides a prism body made of glasstex having a light entrance surface, a light exit surface, and a reflective surface as described above, and a 9AK metal thin film layer and a heat insulating layer on the back side of the reflective surface except for the entrance surface and the light exit surface. and are sequentially laminated and fixed with an adhesive layer interposed between them, making them moisture resistant and
Moisture-proofing can be achieved by using a metal thin film layer, and a heat-insulating layer can prevent sudden temperature changes in the prism body, especially on the reflective surface. It is possible to obtain a stable state of optical image quality under any environment.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is a main surface view of the prism body, FIG. 2 is a side view thereof, FIG. 3 is a rear view, FIG. 4 is a perspective view, and FIG. A cross-sectional view of a part of the laminated member,
FIG. 6 is a perspective view of the completed state, and FIG. 7 is a sectional view of a portion of the ridgeline portion thereof. 1...prism body, 2...participation surface, 4-6...
□Reflecting surface, 7... Light emitting surface, 10... Metal thin film layer, 1
1-12...Adhesive layer, 13...Insulating material Applicant: Ricoh Co., Ltd. 1 Figure] Z Figure 1, 3 Bacteria 14 Figure A 5 Figure 5 Figure 71Q Figure

Claims (1)

[Claims] A prism body is made of plastic and has an entrance surface, a light output surface, two reflective surfaces for reversing and reversing the left and right images, and a reflective surface for reflecting the image toward the light output surface. 1. A pentagonal roof prism characterized in that a thin film layer with low water absorption and a heat insulating layer are stacked and fixed on the back side of a reflective surface excluding the light input surface and the light output surface with an adhesive layer interposed therebetween.