JPS6032071A - image forming device - Google Patents

Abstract

PURPOSE:To obtain a color hard copy faithful to an original simply by detecting the quantity of light of a projected image formed on a Fresnel lens in each color to control light for projecting a color picture. CONSTITUTION:A color slide 13 is exposed by a light source 16 and light transmitted through the slide 13 is separated into three color colors R, G, B by a color separation filter 15, formed an image on the Fresnel lens 3 and then formed the image on a photosensitive drum 6. In order to form proper electrostatic latent images corresponding to three colors on the photosensitive drum 6, the quantity of light of the lamp 16 should be proper in accordance with the density of respective colors R, G, B. Therefore, the quantity of light of three colors which is detected by a light detector 4 arranged on an original platen 2 is compared with the level of the previously fixed reference light of each color and voltage to be impressed to the lamp 16 is controlled respectively on the basis of the difference of light. Thus, the proper light corresponding to the density of the slide 13 is obtained on the photosensitive drum 6.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an image forming apparatus for forming color images.

Conventional technology Conventionally, in color copying machines that obtain color hard copies from color slides, the transmitted light of color slides is divided into red, R, green, and
, Blue B are separated by three color separation filters, each color separated light is irradiated onto a photoreceptor to form an electrostatic latent image, and this electrostatic latent image is developed with cyan C, magenta M, and yellow Y toners, respectively. A color hard copy can be obtained by converting and transferring the image.

At that time, the method of determining each exposure amount to obtain an image with appropriate color balance was to adjust the light amount of a glodiector lamp while looking at the image formed on the recording paper. With this method, after making a few proofs, you manually adjust the light intensity of the rung of the projector to check the color balance, which is time-consuming9, wastes a lot of recording paper, and makes it impossible to faithfully reproduce the color slide. Obtaining color hard copies required considerable experience and skill, and it was not intended that anyone could easily copy them.

Purpose The purpose of the present invention is to solve the above-mentioned drawbacks and to easily obtain a color hard copy that is faithful to the original without the need for several proof printings.

Example The fifth invention will be described in detail below with reference to one drawing.

FIG. 1 is a schematic diagram of a three-time transfer type color copying machine to which the present invention is applied. 1 is a slide projector that projects a color slide 15; 15 is a color separation filter; R, G,
The three B color filters are replaceable. 2 is a document table, 6 is a Fresnel lens placed on the document table, 5 is an imaging lens, 6 is a photosensitive drum, 7 to 12 are each reflecting mirrors, 4 is JG projected on the Fresnel lens, 6 of B
It is a sight detector such as a silicon blue cell that detects the amount of light of each color.

color slide) 16 is a light source (halogen lamp, etc.) 16
The light is exposed to light, and is separated into three colors, R, Q, and H by the transmitted Kosha color separation filter 15, and each separated light is projected onto the Fresnel lens 5 by the lens 14 in the projector 1 via the mirror 7.8. Ru. Here, the Fresnel lens is the exit pupil of the lens 14 in the projector and the lens 50.
It has a conjugate relationship with the entrance pupil. The color-separated and imaged image formed on the Fresnel lens B is then transferred to mirrors 9 and 10.
, lens 5, and mirrors 11 and 12, the image is again formed on the photosensitive drum 6. At this time, projector 1, mirror 7
．． 8 and a Fresnel lens 3, the document table 2 moves in the direction of the arrow in FIG. are formed sequentially. Then, each electrostatic latent image formed on the photosensitive drum 6 is visualized with C, M, and Y toners according to the color of the color separation filter 15, and is superimposed and transferred onto copy paper. You can get a copy.

At this time, in order to form appropriate electrostatic latent images for each of the three colors on the photosensitive drum, the sight of the slide projector 10 lamp 16 must be appropriate according to the density of each of the 83 colors. .

Therefore, it is placed on the document table and R and G are set in advance.

The level of the reference light amount of B and the light amount of each of the six colors detected by the light amount detector 4 are compared with the reference level and the voltage applied to the slide projector 10 lamp 16 is controlled for each of the three colors. That is, the light amount detection is fed back so that the rung light amount becomes the reference level.

Thereby, an appropriate amount of light can be obtained on the photosensitive drum 6 according to the density of the original slide.

BjT　Figure 2 shows a control circuit that performs scene control.

The detection output of the light amount detector 21 provided on the Fresnel lens 6 is amplified by a predetermined value by 1J in an amplifier 22 and then applied to a switching circuit 25 . The switching circuit 25 is operated in accordance with the color exchange of the color separation filter 15 in the projector 1. ■When setting a filter, contact 1 is connected, contact 2 is connected to the G filter, and contact 5 is connected to the B filter. selected. Therefore, the detection output once passed through each color filter is individually transmitted to the subsequent circuit through each contact. 24 to 26 are comparators, and each of the comparators 24 to 26 has a ratio between the output of each contact of the switching circuit 23 and each reference voltage. A reference voltage corresponding to the reference light quantity for G and BK is applied to each of the comparators 24 to 26. Therefore, when the detection output is lower or higher than the reference voltage, a signal indicating the respective state is output.゛Each comparator 24
The comparison outputs of 26 to 26 are input to the switching circuit 27. This switching circuit 27 selects the same contact in synchronization with the switching operation of the switching circuit 25 described above. For example, when the R filter is set, contact 1 of the switching circuits 22 and 27 are both selected.

The output of the switching circuit 27 is applied to the power supply 28 as a power supply control signal. Power supply 28 controls the voltage applied to lamp 29 based on this control signal. Through this feedback control, the rung increments for each color are automatically set to appropriate values.

As described above, when exposing a color film, an appropriate amount of rung light for each color can be automatically obtained, and good color image formation can be achieved.

In this embodiment, the light intensity detector is provided on the Fresnel lens 3 on the original platen 2, but it is not limited to this. It is possible to set it up in - Also, a light intensity detector may be provided exclusively for each color. Further, in addition to the voltage applied to the lamp, current amount control may be performed, for example, by controlling the duty ratio of the applied power.

Effects As explained above, according to the present invention, it is possible to easily make a color hard copy that is faithful to the original slide without manually adjusting the exposure amount.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a copying machine to which the present invention is applied, and FIG. 2 is a circuit diagram for controlling the amount of light from a lamp, in which a Gloziekta manufactured by Ishikawa Co., Ltd., a Fresnel lens 5, and a light amount detector 4 are shown.

Claims (1)

[Claims] means for optically projecting a color image onto a 7-lane lens; means for forming a color image based on the projected image; means for detecting the amount of light in each color of the projected image; and means for forming a color image based on scene detection by the detection means. An image forming apparatus characterized by having an X for projection and a control means for controlling the amount.