JPH0310115B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for recording a composite image in which image information captured by a beam such as a laser beam and a document image are superimposed and recorded.

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 there is still no method that is excellent enough to be put to practical use. Not developed.

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 laser light, it is possible to expose the photoreceptor with laser light deflected by a rotating polygon 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 exposure by original light and exposure by laser light are simply superimposed, the recorded image will be white when one is a white background. Therefore, it is not possible to add information such as characters to the blank area of a document using a laser beam. Therefore, it is necessary to make the information entry area a dark area by blocking the original light, and the area setting means is complicated, making it difficult to put this type of image synthesis apparatus into practical use.

In view of the above points, it is an object of the present invention to make it possible to superimpose the two images described above with an extremely simple configuration that does not require an area setting means.

As a means for achieving this objective, the present invention provides a recording method for obtaining a composite image of an image produced by a beam modulated by an electrical signal and an original image produced by reflected light from the original. This composite image recording method is characterized in that after development, the image is charged again, an electrostatic image is again formed on the photoreceptor by light reflected from the original, and the image is developed again. In addition to laser light, a CRT or the like can also be used as the above-mentioned beam.

First, an example of an electrophotographic copying apparatus to which the method of the present invention can be applied will be explained with reference to the drawings. Conductive substrate 1
a, a primary charger 2, an exposure simultaneous static eliminator 3, facing the circumferential surface of a photoconductor drum on which a photoconductor 1 having a three-layer structure having a photoconductive layer 1b and an insulating layer 1c as a base structure is formed; A developing device 4, a transfer charger 5, a cleaner 6, and a static eliminator 7 are arranged radially. 2, 3, 5, and 7 are corona dischargers with discharge wires.

A document P on a transparent document table 8 is illuminated by an illumination lamp 9, scanned by a scanning mirror 10 that moves together with the lamp, and reflected by a mirror 11 that moves at 1/2 the speed of the mirror 10 to form an image. lens 12,
An optical system including mirrors 13 and 14 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. An electrostatic image of a document image with a high electrostatic contrast is formed on the photoreceptor of the drum by the static elimination by the AC corona discharge of the static eliminator 3 and the next whole surface exposure by the full surface exposure lamp 15. It is visualized by applying toner to the dark areas.

Either transfer paper A or B is in the cassette or paper feed section 1
6 and 17, the toner image is sent in synchronization with the image on the photoreceptor 1, moves in close contact with the photoreceptor 1, and after the toner image is transferred by transfer corona discharge at the position of the transfer charger 5, the toner image shown in FIG. It is separated from the photoconductor 1 by the separation mechanism omitted in , and is transferred to the tray 19 via the fixing section 18.
is discharged. The photoreceptor 1 is cleaned of residual toner by a cleaner 6, neutralized by a static eliminator 7, and then uniformly charged over the entire surface by a primary charger 2.

The above configuration is an example of a known copying apparatus that implements the applicant's NP process described in Japanese Patent Publication No. 42-23910. However, it may also be possible to fix the mirrors 10 and 11 and move the document table 8. be.

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 images the laser beam as a spot light on the photoreceptor 1 at the position of the exposure device 3; It is an imaging lens. Note that a short focus lens array may be used instead of the lens 12, and the rotating polyhedral deflector 20 may be a vibrating mirror. A known laser unit that generates a modulated laser beam upon receiving an output information signal from a computer, word processor, etc. is omitted from the diagram.

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 1 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. The cleaner 6 is retracted to a non-operating position by the advancing/retracting mechanism 22.

The photoreceptor 1 is continuously rotated, and the static eliminator 7 removes the static electricity while holding the toner image, the primary charger 2 charges the photoreceptor 1, and the optical systems 10 to 14 expose the image of the original P. At this time, in the area to which toner is attached (laser beam image area), the document light is blocked by the toner and therefore does not fully bend onto the photoreceptor.
Next, an electrostatic image is formed on the document uniformly exposed by the full-surface exposure lamp 15, but the light source is more powerful than the image light, and since the entire surface is exposed without forming an image, there is no possibility of toner adhesion. The parts are also exposed by 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. This is transferred onto transfer paper, the photoreceptor 1 is cleaned, and the next cycle can be repeated.

Normally, when one electrostatic image is repeatedly developed, the charge of the previously attached toner image is neutralized with the latent image charge, weakening the latent image, and the toner image is disturbed when it is developed again. In the case of the present invention, since the electrostatic image of the document image is formed again with the toner image of the laser beam image still attached, 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-simultaneous static eliminator, static elimination 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 yields a better image.

Figure 2 () shows the result of image synthesis by first performing image formation by beam exposure (digital exposure) and then superimposing image formation by document image exposure (analog exposure) according to the present invention. Image creation process model diagram.Contrary to this, () in the same figure shows the image creation process when image formation is first performed by analog exposure, then image formation is performed by overlaying it by digital exposure, and image synthesis is performed. It is a model diagram.

In the case of (), regarding the halftone part of the first image formed on the photoreceptor surface by image formation by analog exposure, even if this part is hit by digital exposure light during image formation by digital exposure. Since there is toner on that part, the exposure light is blocked, and the potential of that part of the photoconductor cannot be completely lowered. Therefore, toner is deposited on the halftone part in the developing process when forming an image using digital exposure. Further adhesion occurs, and the halftone portion becomes blackish (the halftone cannot be reproduced). In other words, the reproducibility of halftone images obtained by analog exposure is impaired.

On the other hand, when an image is first formed by digital exposure and then an image is formed by analog exposure as shown in (), there is no toner in the halftone exposed area of the photoreceptor during analog exposure. The potential of the photoreceptor surface portion decreases appropriately in accordance with the halftone exposure amount, and in response to the decreased potential, toner adheres appropriately to that portion during the development process, and halftone images obtained by analog exposure are well reproduced. , a high-quality composite image is formed throughout.

In this case, in the developing step when forming an image using analog exposure, toner will further adhere to the image area of the image that has already been formed using digital exposure, but this image area is originally a dark black area, so there is no problem.

The present invention simplifies the device since it does not require an area setting means for erasing a previous image portion corresponding to an image portion to be superimposed later on when recording an image, thereby simplifying the device and making this type of image compositing practical. This has the effect of making it easier to

The invention is not limited to the illustrated NP process and apparatus. That is, it is also applicable to a photoreceptor with a two-layer structure, which does not have a process of static elimination and full-surface exposure at the same time as image exposure.

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 the drawing]

FIG. 1 is a front view showing the arrangement of essential parts of a copying machine, which is an example of an apparatus for carrying out the method of the present invention, and FIG. FIG. 3 is a model diagram of an image creation process in a case where a composite image is obtained () and a case where a composite image is obtained in the reverse order (2); FIG. 1 is the photoreceptor, P is the original, 10, 11, 13, 1
4 is a mirror, 12 is an imaging lens, 20 is a laser beam deflector, and 21 is an f-θ imaging lens.

Claims (1)

[Claims] 1. A recording method for obtaining a composite image of an image produced by a beam modulated by an electrical signal and an original image produced by light reflected from the original, which comprises: developing an electrostatic image formed on a photoreceptor by the beam; A composite image recording method characterized in that the photoreceptor is then charged again, an electrostatic image is again formed on the photoreceptor by light reflected from the original, and the image is developed again.