JPH02110487A - Picture forming device - Google Patents

Abstract

PURPOSE:To superimpose two pictures upon each other with a simple constitution by separating a cleaning means from an image carrying body when the 1st toner image on the image carrying body passes a cleaning position. CONSTITUTION:In this picture forming device which forms a picture in such a way that the 1st toner image is formed by developing the 1st latent image formed on n image carrying body 1 and, after forming the 1st toner image, the 2nd toner image is formed on the image carrying body 1 on which the 1st toner image is formed by developing the 2nd latent image formed on the carrying body 1, a cleaner 6 is retreated to the nonoperating position shown by the double dotted chain line in the figure by means of an advancing and retreating mechanism 22 while the toner images pass through a cleaning position when the toner images pass through the cleaning position. Since the cleaner 6 is retreated, the toner images are not removed or disturbed and can advance to the next image forming process. Therefore, the first formed toner image can be synthesized with the succeedingly formed toner image without being disturbed by the cleaning means 6and such kind of picture synthesization can be put to practical use easily.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a second toner image formed on an image carrier.
The present invention relates to an image forming apparatus that synthesizes toner images.

2. Description of the Related Art In recent years, printing apparatuses that scan and record an electrophotographic photoreceptor using laser light modulated by electrical signals have been put into practical use. Attempts have been made to use this method to convert output information from computers, word processors, etc. into image information and synthesize it with a document image produced by an optical system, but a method that is excellent enough for practical use has not yet been developed. Not yet.

Generally, when copying an original, reflected light from the original is imaged onto a photoreceptor through a lens, etc. to form an electrostatic latent image, and then developed so that toner adheres to the dark areas (image areas). Visual images are usually obtained.

When recording an information image using a laser beam, it is possible to expose the photoreceptor to a laser beam modified by a rotating polyhedral mirror, etc., and apply toner to the dark areas, or reverse development. In order to combine the image with the image, a normal development method is used to attach toner to the dark areas.

In this case, if the original light exposure and the laser light exposure are simply superimposed, if one is on a white background, the written image will be white. It is not possible to add information using a laser beam, so it is necessary to make the information writing area a dark area by blocking the original light, and the means for setting the area is complicated.

In addition, after applying toner to the electrostatic latent image formed according to the original image and developing it, the photoreceptor that forms this toner image is charged again and irradiated with laser light, etc., to create a new image according to the image information. It is conceivable to form an electrostatic latent image, apply toner, and superimpose the two images. But in this case 2
Because it is necessary to align the image formation start positions of the two images, it is necessary to rotate the photoreceptor on which the toner images are formed one or more times more than in the normal image forming process. This caused the inconvenience that the images could not be combined because they were removed, making it impossible to put them into practical use.

The present invention has been made in view of the latter problem, and an object of the present invention is to make it possible to superimpose the two images with an extremely simple configuration.

In order to achieve the above object, the present invention forms a first latent image on an image bearing member, develops the first latent image to form a first toner image, and then holds the image bearing member on which the first toner image is formed. An image forming apparatus that forms a second latent image on a toner image and develops it to form a second toner image, and has a cleaning means that comes into contact with an image carrier to clean the image carrier. The cleaning means is movable toward and away from the image carrier, and is separated from the image carrier when the first toner image on the image carrier passes through a cleaning position.

An embodiment of an electrophotographic copying apparatus according to the present invention will be described with reference to the drawings. Conductive substrate lag photoconductive layer 1b/insulating layer 1
A primary charger 2, a simultaneous exposure static eliminator 3, a developer 4. Transfer charger 5
, a cleaner 6, and a static eliminator 7 are arranged radially. 2・3
Fist 5Φ7 is a corona discharger with a discharge wire.

The document P on the transparent document table 8 is illuminated by an illumination lamp 9,
A mirror 11 that is scanned by a scanning mirror IO that moves together with this lamp and moves at 1/2 the speed of the mirror 10.
It is reflected by the imaging lens 12, mirrors 13, 14, and other optical systems and forms an image on the photoreceptor which has been positively (+) charged by the primary charger 2 at the position of the simultaneous exposure static eliminator 3. The static eliminator 3
An electrostatic image of the document image with a high electrostatic contrast is formed on the photoreceptor of the drum by static elimination by alternating current corona discharge and subsequent full-surface exposure by the full-surface exposure run 15. Next, the normal image area ( It is visualized by applying toner to the dark areas).

Either transfer paper A-H is placed in the tray 2 or paper feed section 16/1.
7, the toner image is sent in synchronization with the image on the photoconductor l, moves in close contact with the photoconductor, and after the toner image is transferred by transfer corona discharge at the position of the transfer charger 5, the toner image is not shown in the figure. It is separated from the photoreceptor l by a separation mechanism, and is discharged to a tray 19 via a fixing section 18. After residual toner is removed from the photoreceptor 1 by a cleaner 6 and static electricity is removed by a static eliminator 7, the entire surface of the photoreceptor 1 is uniformly charged by a charger 2.

The above configuration is an example of a known copying apparatus that implements the NP process of the present applicant described in Japanese Patent Publication No. 42-23910.
may be moved.

20 is a rotary deflector consisting of a polygon mirror that sweeps and projects the laser beam approximately horizontally; 21 has an f-θ characteristic that focuses the laser beam as a spot light on the photoreceptor l at the position of the exposure device 3; It is an imaging lens with a

It is also possible to use a short focus lens array instead of the lenses 1 and 2, and to use a vibrating mirror as the '1 rotation surface body deflector 20. A known laser unit that generates a modulated laser beam upon receiving an output information signal from a computer, a word processor, etc. is omitted in FIG. 1 because it is a known one.

In order to carry out the present invention using the above-exemplified process and apparatus, the exposure section 3 projects a modulated laser light image directly onto the photoreceptor L while rotating the photoreceptor 1 in the direction of the arrow. An electrostatic image is formed using light, and this is developed to form a toner image.

In this case, the transfer paper is not fed, and at this time, the cleaner 6
While this toner image passes, the advancing/retracting mechanism 22 moves the
It is retracted to the inoperative position shown by the dash-dot line.

That is, as the cleaner 6 moves backward, the toner image proceeds to the next image forming process without being removed or disturbed.

The photoreceptor 1 is continuously rotated, and the static eliminator 7 removes the static electricity while holding the toner image, and the negative charger 2 charges the photoreceptor 1, and the optical system 10 to 14 exposes the image of the original P. At this time, in the area where the toner is attached (laser beam image area), the document light is blocked by the toner and does not fully reach the photoreceptor.Then, the entire surface exposure lamp 15 is used to uniformly expose the original light. An electrostatic image of the document is formed, but the light source is more cooperative than the image light, and the entire surface is exposed without forming an image.
The portion to which the toner is attached is also exposed to the scattered light. As a result, an electrostatic image is formed in which the portion exposed to both image lights has a low potential, and the portion exposed by either one has a high potential.

Therefore, when the developing device 4 performs a second development, a visible image is obtained in which the image T produced by the laser beam and the original image are superimposed. After transferring this to the transfer paper, the cleaner 6 comes into contact with the photoreceptor to clean it and repeat the next cycle.

Normally, when two electrostatic images are developed by reversing the edges, the charge of the previously attached toner image is neutralized with the charge of the latent image, weakening the latent image, and the toner image is disturbed when it is developed again. However, in the case of this embodiment, the original image is still static again while the toner image of the laser beam image is still attached. Since 1 tft is formed, this problem does not occur even if the laser beam image is developed twice.

In particular, in the case of a process in which static electricity is removed in the simultaneous exposure static eliminator 3 during the latent image formation process, the above-mentioned problem does not occur because the toner itself is not abnormally charged.

Note that instead of using the above-mentioned exposure and simultaneous static eliminator, static removal and exposure may be performed sequentially.

Contrary to the above example, a toner image of the original image may be formed first and the beam images may be superimposed. However, toner is attached to the halftone part of the original during the first development, and the beam is When exposed and developed a second time, the density of the halftone part becomes high contrast, so the illustrated order provides a better image.

In the present invention, when the toner image formed earlier passes through the cleaning stage during composite recording of one image, the cleaning means is separated from the photoreceptor. It can be combined with a toner image formed later without any disturbance, and has the effect of facilitating the practical application of this type of image combination.

The present invention is not limited to the illustrated NP process and its apparatus, i.e., it uses a two-layered photoreceptor, and simultaneously performs imagewise exposure, removes static electricity,
It also applies to those that do not have a full-surface exposure process.

Note that when exposing the original image, unnecessary parts of the original image can also be erased by irradiating a beam light.

[Brief explanation of drawings]

The drawing is a front view showing the arrangement of essential parts of a copying machine, which is an example of the apparatus of the present invention. (2) is a photoreceptor, P is an original, 10, 11, 13, and 14 are mirrors, 12 is an imaging lens, 2o is a laser beam deflector, and 21 is an f-0 imaging lens.

Claims (1)

[Scope of Claims] After forming a first latent image on an image bearing member and developing it to form a first toner image, a second latent image is formed on the image bearing member on which the first toner image is formed. A latent image is formed, and this is developed to form a second latent image.
An image forming apparatus for forming a toner image, comprising a cleaning means for cleaning the image carrier by coming into contact with the image carrier, the cleaning means being movable toward and away from the image carrier, and for cleaning the image carrier. An image forming apparatus characterized in that the first toner image on the image carrier is separated from the image carrier when it passes through a cleaning position.