JPS5824785B2 - electrophotographic copy printer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic recording apparatus, and more particularly to an electrophotographic copying printer/recording apparatus having both a copy function and a printer function.

Many types of recording devices (including recording, photographing, copying, printing devices, etc.) using electrophotography have already been developed and put into practical use.

In an electrophotographic exposure type copying and recording device, which is one of such recording devices, a corona discharge is applied to the surface of a recording medium made of a photoconductor to uniformly charge it with static electricity, and then the original is printed through an optical system. The recording medium is exposed to light, and the charge on the light-receiving portion is removed in accordance with the original image to bring it to approximately O potential, thereby forming an electrostatic latent image.

This electrostatic latent image is visualized by toner, which is a colored fine powder, in a developing device section, which is transferred onto copy paper and then heated and fixed to obtain a copy of the original.

However, if special paper such as zinc oxide paper is used, the transfer step is not necessary.

In order to write characters, etc. on the margins of images copied by such an electrophotographic copying device, an electrophotographic copying printer device that combines a copying device and an electrophotographic printer device has both a copying function and a printer function. The need is growing.

However, in a copying machine, the image margin of a document becomes a light-receiving part on the surface of a recording medium by exposure, and the electric charge in this part is removed and the potential is almost 0. Even if light is irradiated, a latent image of the characters to be written cannot be formed.

For this reason, in an electrophotographic copying printer device that combines a conventionally swept copying device and a printer device,
A negative image is used as the original for copying, and the area of the recording medium surface that reacts to the image margin during exposure is not exposed to light, thereby retaining the charge in this area and keeping it at a predetermined potential level. This area is irradiated with a laser beam or the like to remove charges corresponding to the characters to be written, thereby forming an electrostatic latent image.

However, in such a conventional method, a normal printed matter cannot be used as it is as a manuscript, and a negative image must be prepared, which is troublesome and extremely inconvenient in practice.

The present invention has been made in view of the above points, and is an electronic true hole recording device having a copying function and a printer function. The object of the present invention is to provide a copy printer device that allows writing operations on copies.

For this reason, in the present invention, in an electrophotographic recording device that combines a copying device and a printer device, the dual-layer image forming devices of the document copying section and the character writing section each have a uniform charge potential on the surface of the recording medium. It is characterized by forming an electrostatic latent image by removing charges at half the potential level.

Hereinafter, the present invention will be explained in more detail based on the drawings.

FIG. 1 is a schematic diagram of an embodiment of an electrophotographic recording apparatus according to the present invention.

A corona discharger 2 for uniform charging, an exposure device 19 for copying, an optical device 20 for recording and writing, a magnetic brush 8 for development, and a magnetic brush 8 for transfer are arranged along the outer circumference of a recording drum 1 having a photoconductor layer (for example, selenium) on its surface. Corona discharger 9 and cleaner 10
is placed.

5 is a copy original, 12 is a transfer paper, 11 is a fixing roller, 18
is toner.

The exposure device 19 for copying consists of a light source 4 and an optical system 3.

The recording/writing optical device 20 includes a laser beam generator, an optical system 6, and a printer control circuit 7.

The amount of exposure onto the recording drum 1 by the exposure device 19 for copying is equal to the uniformly charged charge by the corona discharger 2.

The feed speed of the document 5 is set in advance to determine the exposure time so that half of the charges are removed, or the luminous intensity of the light source 4 is appropriately selected.

Similarly, the amount of laser light irradiation from the laser light generator and optical system 6 of the recording/writing optical device 20 is also the same as that of the recording drum 1 .

The amount of irradiation is set in advance to remove half of the charge uniformly charged on the upper photoconductor layer by the corona discharger 2.

Next, the operation of the electrophotographic recording apparatus having the above configuration will be explained.

The recording drum 1 is rotated as shown by arrow A, and the photoconductor layer on its surface is uniformly charged to, for example, +700V by the corona discharger 2.

The charged state of the recording drum 1 at this time is shown in FIG.

FIG. 2A shows the charge distribution state on the portion of the recording drum 1 corresponding to the copy document 5, and as shown by the loss, the potential level between a and b in FIG.

(For example, +700■).

Subsequently, the copy surface of the original 5 is irradiated with light emitted from the light source 4 of the exposure device 19, and the uniformly charged surface of the recording drum 1 is exposed by the reflected light through the optical system 3 consisting of lenses and the like.

Therefore, the surface of the recording drum 1 corresponding to the margin area other than the image area 14 (see the opening of Figure 3) of the original 5 is exposed, and only half of the charge on this area is removed (see the opening of Figure 3), and As for the potential level, as shown in FIG. 3C, the portion corresponding to the image area 14 is marked ■.

, and the margins other than this area are reduced to ■1.

At this time, as mentioned above, the exposure amount is set in advance to remove an amount of charge corresponding to half the level of the uniformly charged potential.
■).

In this way, a latent image corresponding to the image portion 14 of the copy original 5 is formed on the recording drum 1.

Next, the printer control circuit 7 of the recording/writing optical device 20
For example, as shown in FIG. 4A, the portion 5/lX1. A command is issued by writing symbol 16 into the field.

In response to this command signal, the laser beam generator and optical system 6 perform positive exposure on the surface of the recording drum 1 according to the symbol 16 to be printed.

At this time, the amount of laser light irradiation is set to a level that removes the charge corresponding to half the level of the uniformly charged potential (700V in this case), as described above, so The potential of the latent image area corresponding to the copied image is 700V to 3
50 ■, symbol 1 by optical device for recording and writing
The potential of the part corresponding to 6 is kept at 350V, and the potential level of the other blank areas drops to approximately 0 (Fig. 4, b,
(see c).

In this way, after the latent image forming step by the exposure device 19 for copying, the optical device 20 for recording and writing can form a latent image corresponding to the symbol 16 etc. in the margin of the copied original image, and both latent images can be formed. The potential levels of are equal to 1 (approximately 350V).

Thereafter, as shown in FIG. 5, negatively charged toner (colored fine powder) is deposited on the carrier 17 by the developing magnetic brush 8.
is attracted to the latent image on the recording drum 1 by electrostatic attraction, forming a town prayer image (see FIG. 6).

Next, the toner 18 on the recording drum 1 is attracted to the transfer paper 12 side by the transfer corona discharger 9, and the toner image is transferred to the transfer paper 12.
2, and this is heated and fixed by the fixing roller 11 section.

As described above, in the electrophotographic recording apparatus according to the present invention, the recording/writing optical device is arranged in succession to the exposure device for copying, and characters are written in the margins of the copy document using a copy document with a positive image. etc. can be printed.

In the description of the embodiments, the case where the uniformly charged charge is a positive charge has been described, but the present invention is not limited to this, nor is the type of developer etc.

Although FIG. 1 shows an optical device for recording and writing using a laser scanning optical system, it is also possible to use an optical device for recording and writing that uses a pre-OF recording tube, a laser diode, or the like.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an embodiment of an electrophotographic recording device according to the present invention, and FIG. charge distribution diagram,
Fig. 0 in Fig. 2 is a diagram of the potential level between a and b in Fig. 2, Fig. 3 is a plan view of an example of a copy original, and Fig. 3
Figure 0 in the figure is a charge distribution diagram of the part corresponding to Figure A in Figure 2 after passing through the copying station of the apparatus shown in Figure 1, and Figure C in Figure 3 is a diagram of the charge distribution in the part corresponding to Figure 0 in Figure 3. 4th graph of the potential level between
Figure A in the figure is an example of a symbol written by the optical device for recording and writing, and Figure 0 in Figure 4 corresponds to Figure A in Figure 2 after passing through the optical device for recording and writing of the device shown in Figure 1. Fig. 4 is a graph of the potential level between a and b in Fig. 4, and Fig. 5 is a partial enlarged view of the developing magnetic brush shown in Fig. 1. , and FIG. 6 is a plan view showing the state of toner adhesion at a portion corresponding to FIG. 2 after passing through the magnetic brush portion of the apparatus shown in FIG. 1. 1... Recording drum, 5... Copy original,
19... Exposure device for copying.

Claims (1)

[Scope of Claims] 1. An electrophotographic copying printer comprising at least two sets of latent image forming devices for forming an electrostatic latent image on a uniformly charged surface of a recording medium, wherein a first latent The image forming device is the second
The second latent image forming device removes the charge on the surface of the recording medium while leaving a writable surface potential, and then the remaining charge is removed by the second or subsequent latent image forming device, thereby reducing the electrostatic potential. An electrophotographic copying printer configured to form an image. 2. The electronic device according to claim 1, characterized in that a photoconductor is used as a recording medium, and an exposure type copying and recording device and a recording/writing optical device are provided as the first and second latent image forming devices, respectively. Photocopy printer.