JPS61140966A - Optical device for copying machine - Google Patents

Abstract

PURPOSE:To permit the conversion of the density to be copied according to the color of the image of an original by installing freely insertably color filters into the optical path of the light reflected from the original to expose a photosensitive body. CONSTITUTION:A filter holder 12 is freely movably installed between a near parabolic optical transmission body 3 and a photosensitive belt 1. Three slits 12a, 12b, 12c are opened to the holder 12. The red absorptive filter 13 and the blue absorptive filter 14 are respectively packed into the slits 12a, 12b, 12c positioned on the right and left. The image formed on blue section paper is copied. The operator sets a lever 12d to the position R and copies the image if the operator desires to erase the blue section from the copied image. The exposing ray of the original is then transmitted through the filter 13 and is formed on the belt 1 and therefore the image has the blue ground color. The blue section does not appear on the copied image. A reverse operation may be executed to make reverse emphasis.

Description

[Detailed description of the invention] Technical fields> The present invention relates to an optical system for a copying machine.

<Prior art and its drawbacks> In current copying machines, the emission spectrum of the exposure light source and the spectral sensitivity characteristics of the photoreceptor are constant, so when copying an original that is expressed in multiple colors, the density of the copied image may vary. It was not possible to change the reproduction characteristics. Therefore, for example, when a figure drawn on blue graph paper is copied, the grid is also copied. In the copied image, both the target figure and the grid are drawn in black, so it was sometimes very difficult to distinguish the figure.If the number is 0 or more, the original has a background color. This problem also occurs in cases where it is difficult to distinguish between copied images.

Conversely, when copying a graph recorded on blue graph paper, it is desirable that the graph be copied with the same density as the graph lines, but with conventional copying machines, the graph is drawn in black. , the grid was not copied with the same density as the graph.

<Object of the Invention> In view of the above-mentioned drawbacks, it is an object of the present invention to provide an optical device for a copying machine that can change the density of a copy depending on the color of an image on an original.

<Configuration and Effects of the Invention> The present invention is characterized in that a color filter is freely inserted into the optical path of reflected light from an original that exposes a photoreceptor.

With the above configuration, according to the present invention, the following effects can be achieved.

When copying a color original, if a filter is installed on the optical path that absorbs the color of the image to be copied darkly (black), the image of that color can be copied with approximately the same density as the black image. Furthermore, if there is an image that you do not want to copy, if you install a filter that absorbs the complementary color of that color on the optical path and copy it, almost no image of that color will be copied.

<Embodiment> FIG. 1 is a structural diagram of the main parts of a copying machine equipped with an optical device according to an embodiment of the present invention. This copying machine is a copying machine with a moving original table. A developing device 4 is provided around the photoreceptor belt 1.
Transfer charger5. A static elimination charger 6, a static elimination lamp 7, etc. are provided, and each operates in synchronization with the rotation of the photoreceptor belt 1. The document table 8 is driven left and right by a drive device 10 when the copy switch is turned on. An exposure lamp 2 and a convergent light transmitter 3 are installed between the document table 8 and the photoreceptor belt 1. The exposure lamp 2 illuminates the document set on the document table 8, and the reflected light is transmitted by convergent light. The body 3 is imaged onto the photoreceptor belt 1.

A cassette 9 that stores the paper to be copied is inserted into the lower right part of the copying machine, and the paper sent out from the cassette during copying has the image on the photoreceptor belt 1 transferred to it by the transfer charger 5, and then transferred to the paper by the fixing device 11. The image is fixed and then ejected.

A filter holder 12 is installed between the convergent light transmitter 3 and the photoreceptor belt 1 so as to be movable in the direction of the arrow shown in the figure.

FIGS. 2A, 2B, and 2C are a plan view, a front view, and a side view, respectively, showing a mechanism for installing the filter holder 12 in a copying machine. This filter holder 1
2 has three slits 12a, 12b, and 12c of sufficient size to transmit the reflected light from the original, and red absorption filters 13.2 are provided in the left and right slits 12a, 12c, respectively. A blue absorption filter 14 is inserted. Note that no filter is inserted into the slit 12b, and the filter holder 12 moves on rails 15a and 15b, which are attached to the front and rear surfaces of the copier main body, respectively. lever 12 of the filter holder (
This can be done by manually moving I left and right. displayed on the front of the copier. “B”, “
When the lever is stopped at the "N" and "R" positions, the reflected light from the original passes through the slits of the blue absorption filter, no filter, and red absorption filter, respectively.

For example, if an image created on blue grid paper is to be copied using the copying machine configured as described above, and the blue grid is to be erased from the copied image, the lever 12d is moved to the R position and the copy is made. As a result, the exposure light from the original passes through the red absorption filter 13 and forms an image on the photoreceptor belt l, so the image has a blue background color, and the blue grid does not appear on the copied image. On the other hand, if you want to copy a graph or the like with a density similar to that of a graph curve in which a blue square is drawn in black, set the lever 12d to position B and copy, and the exposure light from the original will be Since the blue component is absorbed by the blue absorption filter 14, the blue grid is imaged black and is copied with approximately the same density as a black image. When erasing or emphasizing a red image, for example, a seal imprint made of ink, it is sufficient to perform the opposite operation to that for the blue grid.

FIG. 3 is a graph showing changes in transmittance depending on wavelength of an example of a red absorption filter. FIG. 4 is a graph showing changes in transmittance of various filters depending on wavelength, and filters of Y43 to Y52 may be used as the blue absorption filter.

The copying machine mentioned above was a copying machine with a movable document table,
Even in the case of a copying machine with a movable optical system, the present invention can be easily implemented by installing a filter on the optical path near the photoreceptor.

[Brief explanation of the drawing]

Fig. 1 is a structural diagram of the main parts of a copying machine equipped with an optical device which is an embodiment of the present invention, and Fig. 2 (A), (B), (C)
are a plan view, a front view, and a side view showing the attachment of the filter holder of the above embodiment, FIG. 3 is a graph showing the transmittance of the red absorption filter, and FIG. 4 is a graph showing the transmittance of the blue absorption filter. 12-filter holder, 13-red absorption filter, 14-blue absorption filter.

Claims (1)

[Claims] (1) An optical device for a copying machine, characterized in that a color filter is freely inserted into the optical path of reflected light from a document that exposes a photoreceptor.