Photographic processing apparatus

Photocopying – Projection printing and copying cameras – Illumination systems or details

Reexamination Certificate

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Details

C355S071000

Reexamination Certificate

active

06204913

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a photographic processing apparatus such as a photographic processing device or photographic printer. In particular, the present invention relates to a photographic processing apparatus having a mirror tunnel for diffusing light from a light source and then leading it onto a film negative. In addition, the present invention relates to a light source device for irradiating light from a light source onto a film negative during a scanning or printing processes.
2. Discussion of the Related Art
Various photo processing apparatuses have been proposed for irradiating light from a light source such as a halogen lamp onto a negative and printing an image of the negative onto a photosensitive material. These photo processing apparatuses are generally provided, for example, with a mirror tunnel
51
shown in
FIG. 5
on an optical path between the light source and the film negative.
FIG. 5
shows a general structure of a mirror tunnel
51
which is referred to, for example, in Japanese Patent Provisional Publication No. 82869 (1996).
The mirror tunnel
51
comprises a cylindrical mirror tunnel main body
53
having a light reflecting surface
52
formed on the inner surface thereof and diffuser plates
54
and
55
, each being disposed on the light incoming side and light outgoing side of the mirror tunnel main body
53
respectively. The diffuser plates
54
and
55
are made of, for example, ground glass or resin such as PMMA (methacrylic resin) and the like containing an opaline pigment.
Due to the structure described above, the light from the light source is diffused by the diffuser plate
54
disposed on the light incoming side of the mirror tunnel
51
as it enters the mirror tunnel
51
. Then the incident light is reflected and diffused by the light reflecting surface
52
in the mirror tunnel
51
. After having been re-diffused by the diffuser plate
55
disposed on the light outgoing side of the mirror tunnel
51
, the light radiates onto the film negative. Even if a point light source such as a halogen lamp and the like is used, the film negative can be substantially uniformly exposed by irradiating the diffused light using the mirror tunnel
51
, so that non-uniform exposure between the optical axis and its periphery can be minimized.
Various light source devices have been proposed for irradiating light from a light source onto a film negative during the process of scanning a photo film or of printing it on a photosensitive material such as photographic printing paper. In these light source devices, a halogen lamp is generally employed as a light source.
Light irradiated from a halogen lamp is non-uniform in quantity due to the shape of the filament or an effect of the reflector. On the other hand, the negative film requires uniform light to be irradiated over the entire image area. Therefore, the light source device is inevitably required to be provided with a structure for making the light from the halogen lamp uniform between the halogen lamp and the film negative.
For uniformalizing light (making the light from the halogen lamp uniform), for example, a structure including an optical condenser lens and an optical diffuser means arranged in this order between the halogen lamp and the negative film is employed. According to this structure, the light irradiated from the halogen lamp is condensed by the condenser lens, and the condensed light is diffused by the optical diffuser means. Thereby uniform light is irradiated onto the film negative. As for the optical diffuser means, for example, a mirror tunnel
51
shown in
FIG. 5
is used.
Since the diffuser plate
54
, as described above, is made of ground glass having opaline materials, the quantity of light is lowered by some one-tenth when light from the light source is transmitted through the diffuser plate
54
, and the same degree of drop in the quantity of light also occurs in the diffuser plate
55
.
On the other hand, when the light source having the structure described above is used, for example, in a scanner, the light irradiated onto a negative film is detected by a CCD (Charge-Coupled Device). The CCD provides an image with wider contrast when the quantity of light received from the image is widely dispersed within a range of the uppermost and the lowermost limits of a sensor of the quantity of light. This means that the light irradiating the negative film is required to have a certain quantity of light.
Therefore, in the structure of the conventional photo processing apparatus, the power of the halogen lamp is increased in order to compensate for decreased quantity of light which occurs when the light from the light source passes through two diffuser plates
54
,
55
. As a result, there are problems with increased power consumption of the halogen lamp and an increased cost of the halogen lamp.
At the same time, there is also a problem of an increased quantity of heat discharged from the halogen lamp due to the increased power of the halogen lamp. This requires a cooling device, for example, a fan for cooling the inside of the light source resulting in an additional increase in power consumption.
Since non-uniformity in illuminance on the film negative increases when the power of the halogen lamp is increased, light diffusion by the light diffuser means has to be further enhanced. For example, in the case described above, the diffuser plates
54
,
55
of the mirror tunnel
51
may be thickened to enhance the diffusion effect in the mirror tunnel
51
. However, the thicker diffuser plates
54
,
55
make the quantity of light lower, and this requires a higher capacity light source.
As an alternative method for preventing non-uniformity in the illuminance on the negative film, the mirror tunnel
51
may be formed longer along an optical axis to increase reflection times in the mirror tunnel
51
and thereby enhance the diffusion effect. However, this method makes the mirror tunnel
51
larger and therefore causes a problem due to the larger size requirement for the light source device itself.
SUMMARY OF THE INVENTION
The present invention is provided to solve the problems described above, and accordingly an object thereof is to provide a photo processing apparatus which enables uniform irradiation on the surface of the film negative without increasing the size of the mirror tunnel so it thereby allows for down-sizing of the device and a reduction in electric power consumption.
In order to solve the above noted problems, the invention provides a photo processing apparatus comprising a diffuser means including a cylinder on whose inner surface is formed a light reflection surface and two diffuser plates each disposed in an end opening of the cylinder. This allows light to be irradiated from a light source through both diffuser plates and the reflection surface onto a photographic film where an original image is recorded. One diffuser plate is disposed on the light incoming side of the diffuser means and has a regularly formed concave and convex shapes thereon so that incident light may pass inside said diffuser means.
According to the structure described above, light from the light source is irradiated onto the film after having been diffused by the diffuser on the light incoming side, the light reflection surface on the inner surface of the cylinder and the diffuser on the light outgoing side. By irradiating the light from the light source onto the photo film through the diffuser means as described above, non-uniformity in the exposure caused by the difference in the quantity of light between the central part and the periphery of the film can be minimized to the greatest extent possible. Thereby substantially uniform light is irradiated over the entire film. Then the original image recorded on the photo film is printed, for example, on the photosensitive material such as photographic printing paper.
Since the diffuser plate disposed on the light incoming side has a regularly formed concave and convex surfaces thereon, the incide

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