JPS614081A - Two-color copying machine - Google Patents

Abstract

PURPOSE:To prevent one of photosensitive bodies which is not used during monochromatic copying operation from being irradiated with unnecessary light by fixing a luminous flux splitting means and providing luminous flux shield members so that they can be put on and off optical paths of split pieces of luminous flux. CONSTITUTION:The two photosensitiv bodies 6 and 7 are provided; both of them is used to take a dichroic copy and one photosensitive body is used to take a monochromatic copy. Luminous flux passed through an image forming lens 1 is split into reflected luminous flux and transmitted luminous flux by a half-mirror 2 fixed at a constant position, and luminous flux shield members 101 and 102 are provided on optical paths of those pieces of split luminous flux. When a black- and-red two-color copy is taken, both shield plates are set at stand-by positions shown by solid lines, and both pieces of luminous flux illuminate both drums 6 and 7, which are exposed. When a black-and-red original is so copied that only a red image is formed in red or that only a black imae is formed in black, equipment relating to either photosensitive drum is turned off and the luminous shield plate on the optical path extending to the drum is put on the optical path as shown by a broken line.

Description

Detailed Description of the Invention Technical Field This invention uses two photoreceptors to copy an original in two colors, black and, for example, red, and uses only one photoreceptor to copy in a single color. This invention relates to a two-color copying machine that makes copies.

BACKGROUND OF THE INVENTION In office documents such as administrative documents and research reports, some text is underlined or framed in red to draw attention to text or drawings that are mainly written in black. is sometimes written in red, and it would be convenient if it could be copied in its original color.

For this purpose, two photoreceptors are provided, and a beam splitting means is provided behind the imaging lens of the exposure optical system to split the light beam reflected from the original and form an image on each photoreceptor for exposure. , electrostatic latent images corresponding to the black and red images on the original are formed on each photoreceptor through a predetermined process, and each latent image is developed with black and red toner, respectively, to form a toner image. A two-color copying machine is known in which a two-color copy is obtained by superimposing and transferring both toner images in the same positional relationship as on a document onto a transfer sheet that is conveyed while sequentially contacting two photoreceptors.

Using the same copying machine, you can copy only the image part of one color from a red-black original in that color, copy the entire image on the original in either black or red, or copy black-and-white from a black-and-white original. If you can make a copy, the convenience will be further improved.

In the monochrome copy mode described above, it is necessary to change the charging conditions of the photoreceptor depending on the mode, or to move the color filter installed in the optical path.
Only one of the photoreceptors is used, and the other photoreceptor is not used.

f = os*, w″′* tri * * 9 f
T! I 1G't Puff S y I=, and for example, if the reflected light beam is projected onto the black photoreceptor and the transmitted light beam is projected onto the red photoreceptor, in all-black copy mode, the black photoreceptor Since only the body is used, the half mirror is removed and a total reflection mirror is inserted in the position where the reflection surface was.
In the red mode, the red filter inserted in the optical path of the reflected light beam was removed, and the entire light beam was projected onto the black photoreceptor.

Further, in a mode in which only the red photoreceptor is used, the half mirror is released as necessary so that the entire amount of light reaches the red photoreceptor.

This method has the advantage that all the light beam from the document can be irradiated onto the photoreceptor on the user side, making it possible to use the light beam effectively and increasing the copying speed, while also providing high mirror positioning accuracy. A mirror switching device is required,
This has the disadvantage of increasing the cost of the device.

Therefore, without using a mirror switching device, a half mirror can be used.
A two-color copying machine in which the light beam is fixedly inserted into the optical path and only one of the divided light beams is used in the monochrome copy mode may have sufficient practical value in some cases.

However, when monochrome copying is performed using a two-color copying machine with a fixed half mirror, the light beam is irradiated onto an unused photoreceptor, which accelerates fatigue and performance deterioration of the photoreceptor, reducing its lifespan. In particular, if the configuration is such that the rotation of the photoconductor is stopped when it is not in use, the light will always be irradiated on only one part of the photoconductor, which will reduce the sensitivity of that part and cause uneven density on the copy. This may cause inconveniences such as:

Purpose The present invention provides a two-color copying machine that is equipped with two photoreceptors, uses both of them to perform two-color copying, and uses one of the photoreceptors to perform single-color copying, and has a fixed light beam splitting means, as described above. To provide a two-color copying machine which solves the problem and prevents unnecessary light from being irradiated onto a photoreceptor on the side that is not used during monochrome copying.

Configuration The present invention achieves the above-mentioned object by providing a light beam shielding method on at least one of the optical paths of the light beam split by the light beam splitting means disposed behind the imaging lens of the exposure optical system and reaching each photoreceptor. It is characterized by being designed so that members can be inserted and withdrawn.

With this configuration, in the monochrome copy mode, by inserting a shielding member in the optical path leading to an unused photoreceptor, it is possible to prevent the light beam from irradiating the photoreceptor.

Embodiments of the present invention will be described in detail below with reference to the drawings.

The attached drawings are diagrams showing the configuration of essential parts of an embodiment of a two-photosensitive drum type two-color copying machine to which the present invention is applied.

This copying machine has a photoreceptor drum 6 for forming a red image and a photoreceptor drum 7 for forming a black image, and a light beam passing through an imaging lens 1 is reflected by a half mirror 2 fixed at a fixed position. It is divided into a luminous flux and a transmitted luminous flux. The reflected light flux is mirror 3
, a red filter 23 and a mirror 4 to form an image on the surface of the black drum 7 at a position 17. On the other hand, the transmitted light beam is reflected by the mirror 5 and is imaged and exposed on the red drum 6 at 10 positions.

Around the red drum 6, there are a primary belt weapon 8, a secondary charger 9, the exposure position 10, an eraser 11, a red developing device 12, a transfer belt 13, a transfer charger 14, and a cleaning device 15. A charging device 16, the exposure position 17, and an eraser 18 are arranged around the black drum 7.
, a black developing device 19, a transfer charger 20, a separation charger 21, and a cleaning device 22 are provided, and these devices pass through a predetermined process to create a color image on the red drum 6 corresponding to the red image of the original. A red toner image is formed, and a black toner image is formed on the black drum 7 corresponding to the black image of the document.

The sum of the circumference from the exposure position 10 to the transfer position 14 of the red drum 6 and the distance between the transfer positions 14 and 20 of both drums is equal to the circumference from the exposure position 17 to the transfer position 20 of the black drum 7. The red toner image formed on the red drum 6'' and the black toner image formed on the black drum 7 are exactly equal. Huio76□n<tv
) The red and black images on the original document are superimposed and transferred onto a transfer paper conveyed from 13K so as to be in contact with the transfer portions of both photosensitive drums 6.7, thereby obtaining a red and black two-color copy.

A light beam shielding plate 101 is placed on the optical path from the mirror 5 to the red drum 6, and a light beam shielding plate 102 is placed on the optical path between the mirror 3 and the mirror 4, respectively, at the position shown by the broken line and retreated from the optical path. When making the above-mentioned red and black two-color copy, both light beam shielding plates occupy the retracted position shown by the solid line, and both light beams are disposed between the two drums. Expose by irradiating 6.7.

When copying only the red image of the original in red or only the black image of the original in black from a red-black original, the related process equipment of either one of the photosensitive drums may be deactivated. The photoreceptor drum that is not used at this time may or may not be rotating. In any case, a light beam shielding plate provided on the optical path leading to the unused photoreceptor drum is inserted into the optical path. Therefore, unused photosensitive drums are not unnecessarily irradiated. Further, by changing the charging conditions of the secondary charger 9 of the red drum 6 and deactivating the related process equipment of the black drum, all images of the red and black original can be copied in red. In this case, by inserting the light flux shielding plate 102 into the optical path, the unused black drum 7 is prevented from being irradiated.

In addition, when making a black and white copy from a black and white original or a multicolor original, the red drum and its related process equipment are deactivated, the red filter 23 is released, the black drum 7 is exposed, and the transfer paper is placed on the transfer belt 13. The paper is directly fed to the transfer section 20 of the black drum 7 from the lower conveyance path without passing through the paper. In this case, the red drum 6 is prevented from being irradiated by inserting the light beam shielding plate 101 into the optical path.

It is preferable that the displacement between the insertion and withdrawal positions of the light beam shielding plates 101 and 102 in the optical path in each of the above modes is performed by operating a solenoid in conjunction with the selection operation of the copy mode selection switch. .

In the above embodiment, a light beam shielding plate is provided in the optical path of both light beams divided by the half mirror, but for example, if only red copies are rarely made, the light path leading to the black drum may be used. The light flux shielding plate may be omitted.

The present invention is applicable not only to the black and red two-color copying machine shown in the embodiments, but also to
It can also be applied to a two-color copying machine that copies two-color originals of black and other chromatic colors.

Effects As described above, according to the present invention, there is no need for a device for precisely positioning and switching between a half mirror and a total reflection mirror, which is effective in reducing costs.During monochrome copying, unused photoreceptors are used to reduce the light flux. Since the photoreceptor is not irradiated with light, fatigue of the photoreceptor and shortening of its life can be prevented. In particular, if the configuration is such that the photoreceptor is stopped when it is not in use, unevenness in image density on copies due to partial deterioration of performance can be prevented. It can be prevented.

[Brief explanation of drawings]

The accompanying drawings are cross-sectional views showing essential parts of embodiments of the present invention. 1... Imaging lens 2... Half mirror (light beam splitting means) 3.4. ．． 5.
...Mirror 6...Photoreceptor 7 for chromatic image formation...Photoreceptor 10.17 for black image formation...Exposure position 12.19...Developing device 14.20...Transfer charger 45. ...Paper feeding section 101.102...Light flux shielding member--3

Claims (1)

[Claims] The light beam reflected from the document placed on the document table and drawn in black and a second chromatic color is divided by a beam splitting means placed behind the imaging lens of the exposure scanning optical system. The respective light beams are image-formed and exposed at predetermined projection positions on different photoreceptors, and electrostatic latent particles corresponding to the black image area and the second color image area on the document are formed on each photoreceptor through a predetermined process. Each electrostatic latent image is developed with toner of two different colors to form a toner image, so that the toner images on these two photoreceptors are transferred in the same positional relationship as on the original. Two-color copying in which two-color copies are made by sequentially overlapping transfers onto transfer paper that is conveyed in contact with both photoconductors, and one-color copies are made using only one of the photoconductors. The light beam splitting means is fixed in an immovable position, and a light beam shielding member is provided in at least one of the optical paths of the light beam split by the light beam splitting means so as to be insertable and retractable. Two-color copying machine.