Photocopying – Projection printing and copying cameras – Multicolor picture
Reexamination Certificate
2003-02-05
2004-08-10
Mathews, Alan (Department: 2851)
Photocopying
Projection printing and copying cameras
Multicolor picture
C355S067000, C355S071000, C353S033000, C359S638000
Reexamination Certificate
active
06774979
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image exposure apparatus, and in particular, to an image exposure apparatus that exposes photosensitive materials by using rays of light each having a different wavelength emitted from a plurality of light-emitting elements.
BACKGROUND OF THE INVENTION
In recent years, there has been proposed to be put to practical use an image exposure apparatus that is equipped with array light sources each being composed of a plurality of light-emitting elements for each recording color.
FIG. 9
is an illustration showing how exposure is carried out in the conventional image exposure apparatus. This image exposure apparatus is equipped with three array light sources
210
,
220
and
230
each having substantially the same width as in photographic paper
100
, for exposing the photographic paper
100
to light.
Each of these three array light sources
210
,
220
and
230
emits light in accordance with each of R, G and B recording colors. When photographic paper
100
is conveyed in the direction of an arrow in the drawing, each of the array light sources
210
,
220
and
230
was driven by staggering timing in accordance with the conveyance speed of the photographic paper
100
so that exposures for R, G and B may be conducted on the same position on the photographic paper
100
.
When driving each of the array light sources
210
,
220
and
230
by staggering the timing in accordance with the conveyance speed of the photographic paper
100
, it is necessary to stagger the timing of driving signals to be supplied to each array light source in accordance with the conveyance speed. Therefore, there has been a problem that the structure of a driving circuit and control of the timing are complicated. Further, if the conveyance speed fails to be constant during the period from completion of exposure of a certain recording color to exposure of another color for the same pixel, there is caused a problem of out of color registration. For preventing the out of color registration, therefore, it was necessary to control strictly the conveyance speed for photographic paper
100
.
To solve the problems stated above, there has been suggested a method to mix array-shaped emergent light emitted from each array light source, by using a light-mixing member such as dichroic prism
300
equipped with a light selective film that transmits or reflects light selectively depending on a wavelength.
FIG. 10
is a schematic diagram showing how the dichroic prism
300
mixes light.
The dichroic prism
300
is composed of first transparent member
310
, second transparent member
320
and third transparent member
330
which are made of optical glass. Between the first transparent member
310
and the second transparent member
320
, there is provided first light selective film
340
that transmits or reflects selectively depending on a wavelength of light. In the same way, there is provided second light selective film
350
that transmits or reflects selectively depending on a wavelength of light, between the second transparent member
320
and the third transparent member
330
.
When the dichroic prism
300
of this kind is used, linear emergent light emitted from array light source
210
is transmitted successively through the first transparent member
310
, the first light selective film
340
, the second transparent member
320
, the second light selective film
350
and the third transparent member
330
, and emerges. On the other hand, linear emergent light emitted from array light source
220
is transmitted through the second transparent member
320
and is reflected on the first light selective film
340
, then, is transmitted successively through the second light selective film
350
and the third transparent member
330
, and emerges. Further, linear emergent light emitted from array light source
230
is transmitted through the third transparent member
330
and is reflected on the second light selective film
350
, to emerge. Through the paths mentioned above, each linear emergent light emitted from each of array light sources
210
,
220
and
230
is tied up in a line.
An ordinary method to be employed for providing light selective films
340
and
350
on the dichroic prism
300
of this kind is one to deposit a metal such as aluminum or silver on a transparent member. However, each of transparent members
310
,
320
and
330
constituting the dichroic prism
300
is a relatively long member matching with a line length of the array light source, and “a warp” is frequently caused in the longitudinal direction by heating in the course of deposition accordingly. When these transparent members each having “a warp” were jointed with each other, bubbles were generated between both transparent members or “a warp” was generated on the total product in some cases to deteriorate quality.
In the conventional dichroic prism
300
, there was provided composition plane
360
having a relatively large area, as shown in
FIG. 10
, in addition to the composition plane forming the first light selective film
340
and the second light selective film
350
, thus, an area of the total composition planes was great. When an area of the total composition planes is great, the possibility for both “warped” portions of the transparent members to come into contact with each other is great, thus, the problem of the quality deterioration has tended to happen.
Next, the first light selective film
340
and the second light selective film
350
both provided on the dichroic prism
300
have characteristics to transmit or reflect selectively depending on a wavelength of light as stated above. In general, when the light selective films have the characteristics of this kind, each of them needs to have a complicated layer structure having a certain extent of thickness.
However, each of the first light selective film
340
and the second light selective film
350
is provided at the portion sandwiched by the transparent members, and therefore, it is difficult for each of them to have the complicated layer structure having a sufficient thickness. For this reason, it is sometimes impossible to demonstrate sufficient transmission/reflection characteristics.
For example, when P polarized light and S polarized light are mixed in emergent light emitted from an array light source, a difference tends to be caused on a wavelength for the P polarized light in the case of switching from transmission to reflection and on a wavelength for the S polarized light in the case of switching from transmission to reflection, and if this difference is caused, the P polarized light and the S polarized light are averaged, and the intermediate state between transmission and reflection (half-transmitting and half-reflecting) is caused. As a result, efficiency of using light is sometimes lowered.
In this case, if a wavelength of P polarized light in the case of switching from transmission to reflection and a wavelength of S polarized light in the case of switching from transmission to reflection can be made to be close each other, it is possible to solve the aforesaid problem that efficiency of using light is lowered. However, for this purpose, the light selective film needs to be thick, and it has been difficult to construct a thick light selective film on the portion sandwiched by transparent members.
DISCLOSURE OF THE INVENTION
To overcome the abovementioned drawbacks, it is a first object of the present invention to provide a high-quality light-mixing part (hereinafter, also referred to as an optical device) having little warp in its longitudinal direction, and an image-exposing apparatus provided with the abovementioned light-mixing part and an image-exposing method employing the abovementioned light-mixing part.
Further, it is a second object of the present invention that, in an image-exposing apparatus which mixes a plurality of lights having wavelengths different relative to each other and emitted from a plurality of light-emitting elements to expose a photosensitive material, deter
Frishauf Holtz Goodman & Chick P.C.
Konica Corporation
Mathews Alan
LandOfFree
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