JPH059166Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a lamp house for a plate-making device for thermal stencil printing.

Conventional heat-sensitive stencil paper is attached to the lower surface of a transparent plate on the bottom of the lamp house, the base paper on the bottom of the lamp house is pressed onto the document placed on a substrate made of an elastic material, and the lamp inside the lamp house is turned on to convert the heat-sensitive stencil paper into a heat-sensitive stencil paper. A plate-making device for thermal stencil printing is well known, which is capable of producing a thermal stencil by perforating holes in accordance with a document.

In the above device, it is desirable that the light irradiated onto the transparent plate be uniform over the entire surface and have high irradiation efficiency. For this purpose, conventionally, as shown in FIG. 1, a mirror-finished aluminum 2 is used on the inner surface of the lamp house 1, and a large number of protrusions 2a are formed on the surface, and as shown in FIG. However, since the directions of light scattering are random, multiple reflections are likely to occur as shown in Figure 3, resulting in a decrease in irradiation efficiency, and the former requires complicated processing and is expensive. However, the latter had the disadvantage that the level of surface roughness was small, light absorption easily occurred, and the reflectance level itself decreased.

Therefore, it has been considered to make the mirror surface 6 of the lamp house 5 a mirror surface, as shown in FIG. 4, and to arrange the light source 7 at its focal point. A mirror surface 6 consisting of a parapet surface from a light source 7
Since the distance to the irradiation surface 8 is approximately equal, the irradiation distribution due to the reflected light is approximately equal, but the direct light distribution from the light source 7 is strongest in the center and becomes weaker toward the left and right. Therefore, there was a drawback that the irradiation distribution on the irradiation surface 8 as a whole became non-uniform.

Therefore, as shown in FIG. 5, the inner surface of the lamp house is formed by two symmetrical rectangular surfaces 12 and 13 with the center 11 of the light source 10 as a common focal point, and the lower two focal points 14 and 15 are formed by a rectangular transparent press. We considered placing the light sources around the four side edges of the plate 16, but since the reflected light from the light source 10 is all concentrated at the lower two focal points 14 and 15, we decided to place the light sources on the transparent press plate 16 shown in FIG. In the irradiation distribution, peak portions 17 and 18 were formed on the left and right sides, and the amount of light was reduced in the central portion, resulting in non-uniform irradiation of the transparent press plate 16.

The present invention uses a mirror surface consisting of a rectangular surface with a focal point shifted a certain distance upward from the center of the light source to form the inner surfaces of the four side walls with the light source at the top, and the distribution of reflected light from the light source is reflected from the heat-sensitive stencil paper on the bottom surface. The green area on all four sides of the rectangular transparent press plate on the bottom of the lamp house that is attached to the lamp house is strengthened, and when combined with direct light, a uniform irradiation distribution is obtained as a whole, eliminating the drawbacks of the conventional lamp. be.

FIG. 7 shows an embodiment of the present invention. Reference numeral 20 denotes a lamp house having a light source 21 at the top and side walls 20a on four sides, and the side walls 20a are arranged symmetrically with a common focal point 22 at a position shifted a certain distance upward from the center of the light source 21, as shown in FIG. formed 2
It is a mirror surface consisting of two circular surfaces 23 and 24. The lower focal points 26 and 27 of the elongated circular surfaces 23 and 24 are located at the green portions around the four side edges of the rectangular transparent press plate 25 on the lower surface of the lamp house 20.

Next, the operation will be described.

In the present invention, as shown in FIG. 8, the center of the light source 21 and the common focal point 22 are not aligned, but the common focal point 22 is positioned a certain distance above the center of the light source 21.
As shown in FIG. 9, the lower focus 2 of the transparent pressing plate 25
Rather than concentrating on 6 and 27, the light source 2
In combination with the direct light 1, the irradiation distribution of the light is substantially uniform over the entire surface of the rectangular transparent press plate 25.

Note that the distance by which the common focal point 22 is shifted upward from the center of the light source 21 is arbitrarily determined.

According to the present invention, the inner surfaces of the side walls on all four sides are formed with a mirror surface consisting of a rectangular surface with the focal point shifted a certain distance upward from the center of the light source, with the light source at the top.
Without providing a large number of protrusions on the mirror surface, the irradiation distribution of the rectangular transparent plate to which the heat-sensitive stencil paper is attached can be made substantially uniform over the entire surface.

[Brief explanation of the drawing]

1 and 2 are front sectional views of a conventional first comparative example and a second comparative example, FIG. 3 is a diagram explaining the conventional operation, FIG. 4 is a front sectional view of a conventional third comparative example, and FIG. 5 is a front sectional view of the fourth comparative example, FIG. 6 is the irradiation distribution diagram of FIG. 5, and FIG.
The figure is a perspective view of one embodiment of the present invention, FIG. 8 is a sectional view of the main part of FIG. 7, and FIG. 9 is an irradiation distribution diagram of FIG. 7. Light source...21, common focus...22, ellipsoidal surface...
23, 24, side wall...20a, downward focus...2
6, 27, Transparent pressure plate...25, Lamp house...
...20.

Claims (1)

[Scope of utility model registration request] A mirror surface consisting of a rectangular surface whose focal point is shifted a certain distance upward from the center of the light source, with the light source as the top, forming the inner surface of the four side walls, and the lower focus of each rectangular surface is set at the four sides of a rectangular transparent pressing plate. The lamp house of the plate-making device for thermal stencil printing is located in the surrounding green area.