JPS644115Y2 - - Google Patents

Description

[Detailed description of the invention] This invention modulates the ion flow by using a primary electrostatic image formed on the outer surface of a photosensitive screen with a large number of fine apertures stretched over a drum frame. The present invention relates to an electrostatic recording device that forms a secondary electrostatic image by projecting a particle stream onto a surface.

With this device, it is possible to obtain a monochrome image using a method of forming an electrostatic latent image corresponding to the original in the monochrome image area and developing it to obtain a visible image. and a color image area such as red or blue, to form an image in which this is expressed, that is, to form an electrostatic latent image and develop it to obtain a visible image. It is also possible to form color images.

Generally, it is impossible to develop only a specific partial area of one electrostatic latent image formed by electrostatic photography, electrostatic printing, etc., and the entire electrostatic latent image can be developed using the same developer. It is then developed. Therefore, when forming an image expressed in multiple colors as a whole using a method of developing an electrostatic latent image to obtain a visible image, it is necessary to develop an electrostatic latent image that corresponds only to an image area of a certain color. For each color, it is necessary to form an image and develop it with a developer of that color.

For these reasons, conventionally when forming a multi-color image, a first electrostatic latent image is formed and developed with a first color developer, and the resulting first color visible image is transferred to transfer paper. After being transferred, it is fixed as necessary, and then a second electrostatic latent image is formed and developed with a second color developer, and the first color visible image is transferred and fixed as necessary. In other words, an electrostatic latent image is formed for each color, and the processes of development, transfer, and fixing are repeated.

According to such a method, the image portions of each color can be reliably formed as such, but in the transfer performed for the visible image of each color, the transfer paper is transferred to the electrostatic image support carrying the visible image. It is extremely difficult to make the transfer images of each color come into contact with each other in exactly the same position, and a slight positional shift occurs in the transferred images of each color, making it impossible to form a desirable multi-color image. Furthermore, if the visible images of each color are not fixed each time they are transferred, there is a risk that the already formed visible images will be disturbed in the subsequent visible image transfer step. Therefore, a series of image forming steps are performed for each color, but this requires a large number of steps and takes a long time. When forming a copy image by electrophotography using a document having a black image area and a color image area, it is desirable that the black image area be reproduced using only black toner. The reason for this is that it is actually very difficult to reproduce true black by mixing the so-called three primary colors, and when toner of a certain color adheres, it is necessary to layer black toner on top of it. Even when black image areas are reproduced by color printing, it is difficult to make the images created by each toner perfectly match, and it is difficult to reproduce a color copy image in which black image areas such as black lines and black characters are clearly reproduced. should be developed with black toner only.

In electrophotography, forming an electrostatic image in which electrostatic charges exist only in the area corresponding to the black image area is achieved by uniformly charging the optical image of the original through a three-primary color filter. Although this can be achieved relatively easily by irradiating a photoconductive photoreceptor, it is difficult to form an electrostatic charge image that erases the black image area because the black image area absorbs all the light. Conventionally, for example, a method including complicated steps such as once forming a negative image corresponding to the black image area and utilizing this has to be used.

This apparatus uses a charged particle flow control screen to extremely easily form an electrostatic charge image with the black image area erased from a document having a black image area and a color image area, and
Developing the formed electrostatic charge image with toner of the same color as the color image area of the corresponding document, or repeating this operation for each color image area;
This method combines the steps of forming an electrostatic charge image having electrostatic charge only in the area corresponding to the black image area of the document and developing it with black toner, thereby clearly reproducing the black image area. Two-color or multi-color reproduction images can be obtained.

The principle of the electrostatic recording device according to the present invention will be explained below with reference to the drawings, in the case where it is applied to a method of forming a black and red two-color printed copy image using an original having a red image area as an example of the color image area. Next, the present electrostatic recording device will be explained. As shown in FIG. 1A, with the support 1 of a photoreceptor 3 comprising a conductive support 1 provided with a photoconductive photosensitive layer 2 made of, for example, selenium-tellurium, being grounded, a corona charger 4 is used to The photosensitive layer 2 is uniformly and positively charged, and then, as shown in FIG. The photosensitive layer 2 is irradiated through the photosensitive layer 2. As a result, the photosensitive layer 2 is irradiated with light to areas other than the areas corresponding to the black image area B and red image area R, and the static charge disappears.
As a result, a first electrostatic charge image having positive electrostatic charges only in the area is formed.

On the other hand, as shown in FIG.
A charged particle flow control screen (hereinafter simply referred to as a "screen") is formed by forming a photoconductive layer 71 made of, for example, selenium-tellurium on one side, an insulating layer 73 on the other side, and a conductive bias layer 74 on the outside thereof. ”
It is abbreviated as ) 7, the photoconductive layer 71 is shown in FIG. 3A.
As shown in FIG. 3B, the conductor mesh 72 is grounded and uniformly positively charged by the corona charger 8. Next, as shown in FIG. The screen 7
The photoconductive layer 71 of is irradiated with light. As a result, a second electrostatic charge image is formed on the photoconductive layer 71 of the screen 7, having positive electrostatic charges only in the area corresponding to the black image area B. It is assumed that the light image of the original 5 irradiated onto the screen 7 is a mirror image of the light image on the photosensitive layer 2 of the photoreceptor 3.

Next, as shown in FIG. 4, the second electrostatic charge image is applied to the photosensitive layer 2 of the photosensitive member 3 having the first electrostatic charge image.
The screen 7 is arranged so that the photoconductive layer 71 having an electrostatic charge image faces it, and a bias voltage of an appropriate magnitude having the same polarity as the electrostatic charge image on the photoconductive layer 71 is applied to the conductive bias layer 74 of the screen 7. charged particle source 10 through the screen 7 with
The more negatively charged particle flow is applied to the photosensitive layer 2 of the photoreceptor 3.
The images are projected using an electric field applied between the photoreceptor 3 and the charged particle source 10. As a result, the negatively charged particle flow from the charged particle source 10 passes through the screen 7 in areas where the photoconductive layer 71 of the screen 7 has a positive electrostatic charge, and is blocked from passing in other areas. As a result, the positive electrostatic charges only in the area corresponding to the black image area B of the first electrostatic charge image in the photosensitive layer 2 of the photoreceptor 3 can be eliminated, and eventually the photosensitive layer An erased electrostatic charge image of the black image portion having electrostatic charge only in the region corresponding to the red image portion R of No. 2 is formed. In addition, in this invention, for example,
-59840, 50-36137, U.S. Patent No.
Any of the charged particle control methods using a screen photoreceptor described in No. 3713734 and No. 3680954 can be used.

The desired electrostatic charge image is formed as described above, and by developing this electrostatic charge image with red toner, a red reproduction portion RT is formed on the photoreceptor 3 as shown in FIG. Ru. In order to further reproduce a black image, a separate step of forming a black image may be performed. That is, as shown in FIG. 6A, the photosensitive layer 2 of the photoreceptor 3 is uniformly positively charged by the corona charger 4, and then, as shown in FIG. 6B, the optical image of the original 5 is colored red. The photosensitive layer 2 is irradiated through the filter 9 to form a black image area electrostatic charge image having positive electrostatic charge only in the area corresponding to the black image area B of the document 5, and this is transferred to the black toner. Develop.

Therefore, in order to form a two-color printed copy image corresponding to the original 5 having the black image area B and the red image area R, the red reproduction section described with reference to FIGS.
It is sufficient to combine the step of forming only RT and the step of forming the black reproduction portion BT exemplarily described with reference to FIG. That is, by performing the formation process of the red reproduction part RT and the formation process of the black reproduction part BT separately and transferring and fixing each toner image to the same transfer paper, or after forming the black reproduction part BT. By carrying out the step of forming the red reproduction part RT, the black reproduction part BT and the red reproduction part RT are formed on the same photoreceptor as shown in FIG. 7, and by transferring and fixing this onto a transfer paper, A copy image of the original document 5 can be obtained. In this way, an electrostatic charge image with the black image area erased can be formed very easily without forming a negative image or other complicated steps, and therefore the color image area and the black image area are each reproduced independently. This makes it possible to obtain a copy image in which each image part is clear and beautiful. Of course, even if the color image portion is a chromatic color other than red, it can be reproduced in the same manner.

FIG. 8 shows an electrostatic recording device in which a photosensitive screen is stretched over a drum-shaped frame (to form a two-color copy image) using the above-mentioned principle. In this apparatus, reference numeral 11 denotes an original table that reciprocates from side to side, and an original 5 is placed on a glass plate 12, which is illuminated by an illumination lamp 13. 14a and 14b are surface reflecting mirrors, 15 is a fixed lens, and 9 is a red movable filter. 16 is a movable dichroic filter; when the red filter 9 is in the optical path, the dichroic filter 16 is outside the optical path; when the red filter 9 is outside the optical path, the dichroic filter 16 is
is within the optical path. The drum-shaped photosensitive layer 2 rotates clockwise and is uniformly charged by a corona charger 4. The photosensitive layer 2 may be an electrophotographic photoreceptor such as selenium or an organic semiconductor. If the photosensitive layer 2 is made of selenium, it will be positively charged by the charger 4. Since the photosensitive layer 2 rotates in synchronization with the document table 11, the red filter 9
is in the optical path, a black image area electrostatic charge image having positive electrostatic charge only in the area corresponding to the black image area B of the original 5 is formed as shown in FIG. 6B. becomes. 17 is a black developing device, and 18 is a red developing device. 19 is a transfer paper feeding plate, and 20 is a transfer drum. A transfer paper is electrostatically held around the circumference of the transfer drum 20, and the black image portion electrostatic charge image formed on the previous photosensitive drum 2 is developed by a black developing device 17 and then transferred onto the transfer paper. to obtain a black image. Next, the document table 11 is returned to the initial position, the red filter 9 is moved out of the optical path, and the dichroic filter 16 is moved into the optical path, and synchronous exposure is performed again. In the figure, 7 is a charged particle flow control screen stretched over a drum-shaped frame, 8 is a corona charger, and 10 is a charged particle source disposed within the drum. Charged particle flow control screen 7 rotates in synchronization with document table 11 and photosensitive layer 2 . By inserting the dichroic mirror 16 into the optical path, the reflected line of the dichroic mirror 16 is reflected on the charged particle flow control screen 7 previously charged by the corona charger 8, with the same effect as if a red filter was inserted. As explained above with reference to FIG. 3B, a second electrostatic charge image having positive electrostatic charges is formed only in the area corresponding to the black image portion B.
The light transmitted through one of the dichroic mirrors 16 is cyan light, and as shown in FIG. is irradiated, the electrostatic charge disappears, and a first electrostatic charge image is formed in which only the region has positive electrostatic charge. The charged particle flow control screen 7 rotates counterclockwise, and the first electrostatic charge image and the electrostatic charge image are positioned so as to synchronize and face each other.

When a negatively charged particle stream is projected from the charged particle source 10, an electrostatic image is formed on the photosensitive layer 20 only in the area corresponding to the red image area R, as shown in FIG. 4 in the above explanation. be done. Therefore, as the photoreceptor 2 rotates, development is performed by the red developing device 18, and by transfer, a red image is superimposed on the transfer paper having the black image. Note that the order of transfer may be to print red first, then black. The transfer paper carrying the two-color image is separated from the transfer drum 20, the toner is fixed on the transfer paper by the fixing device 21, and the transfer paper is discharged outside the machine.

An electrostatic recording device that modulates ion flow to form a secondary electrostatic image by using an electrostatic image formed on the surface of a photosensitive screen having a large number of openings stretched over a drum-shaped frame as described above. As mentioned above, the image forming member, for example, the charged particle source 1 in the above description, is placed in a rotating drum on which a photosensitive screen is stretched.
0 must be fixed at a predetermined position.
A technique for fixing such an image forming member in a fixed position has already been disclosed in Japanese Patent Application Laid-Open No. 133840/1984 or Japanese Patent Publication No. 30292/1982. However, in their invention, the drum frame and the internal image forming fixing member come into significant contact, which not only requires a lot of power to drive the drum rotation from the outside, but also makes the entire circumference of the drum a photosensitive screen. This is a problem, and furthermore, attaching and detaching the fixing member to the drum is complicated, and it is especially difficult and time consuming to slightly adjust the fixing position of the fixing member. It was hot.

The present invention utilizes magnetic force to fix an image forming member rotatably supported within the drum-shaped frame in the electrostatic recording device, an example of which has already been described. The above-mentioned shortcomings that needed to be resolved were wiped out. Examples will be explained with reference to the drawings. FIG. 9 is a sectional view taken parallel to the axis of the photosensitive screen drum. Flanges 81 are located at both ends of the drum and are fixed to the rotating shaft 82 with screws. Flange 8
1 has slide electrodes 83 and 84 concentrically arranged (see FIG. 10b), connected to the inside and outside of the drum by brushes, and used as a conductive circuit for screen control and corona discharge. The photosensitive screen 7 is attached to the circumferential surface of the flange 81 with adhesive.
A rotating shaft 82 of the drum is rotatable with respect to the main body E of the electrostatic recording device via a bearing 85, and a gear 8 is fixed to the rotating shaft 82 with a screw.
6, it rotates in synchronization with external related members. On the other hand, the pipe 88 is rotatably attached to the rotating shaft 82 via a bearing 87. In other words, the drum can rotate or remain stationary, and as shown in Figure 10a, which shows the AA cross section of Figure 9, a charged particle source 10 for corona discharge, a magnet, etc. 89, balancer 90
are each attached integrally via an arm. On the other hand, a magnet 91 that attracts the magnet 89 and the magnet 91 is fixed to the main body E side. The magnets 89 and 91 attract each other through the space in the screen portion and remain fixed even when the drum rotates. The balancer 90 maintains a balance with the charged particle source 10 and has the effect of stopping at a desired position even by the earth's gravitational force. As for how to use the magnet, a structure as shown in the embodiment shown in FIG. 11 is also possible, and it is also possible to use a plurality of magnets, but in any case, the image forming member can be rotated within the drum-shaped frame. A means is used in which a magnet that supports the image forming member and is attached integrally with the image forming member and a magnet that attracts or repels the image forming member are attached to the main body side and are fixed by the attractive force or the repulsive force of both. devised. The rotating drum-shaped frame is made of metal that is not easily affected by magnetic force, such as aluminum.
Preferably, it is constructed from a non-magnetic material such as brass. The effects of this invention have been mentioned earlier, but
For example, when you want to slightly move and adjust the charged particle source 10, you can achieve the desired purpose by slightly moving the magnet 91 on the main body E side without dismantling the drum each time.This is an extremely effective device. It became clear that.

[Brief explanation of drawings]

Figures 1 to 7 are diagrams explaining the principle of the electrostatic recording device of the present invention, and Figures 1, 3, and 4 respectively use a document having a black image area and a red image area; An explanatory diagram showing the first electrostatic charge image formation step, the second electrostatic charge image formation step, and the final step regarding an example of the method for forming an erased electrostatic charge image, and FIG. 2 shows charged particles used in this apparatus. An explanatory diagram showing the configuration of the flow control screen, FIG. 5 is an explanatory diagram when the electrostatic charge image obtained in the above embodiment is developed into red color, and FIG. 6 is an explanatory diagram showing the process of reproducing the black image area. FIG. 7 is an explanatory diagram of a toner image for a two-color copy image obtained by applying the apparatus of the present invention. Figure 8 is a structural layout diagram of the electrostatic recording device of the present invention, Figure 9 is a sectional view taken parallel to the axis of the photosensitive screen drum, and Figures 10a and 10b are Figure 9A.
A sectional view and a view from B are shown, and FIG. 11 is a partial sectional view showing another embodiment of the magnet. 2... Electrostatic photosensitive layer, 4, 8... Corona charger,
7...Charged particle flow control screen, 9...Red filter, 10...Charged particle source, 16...Dichroic filter, 89, 91...Magnet.

Claims (1)

[Scope of utility model registration request] The ion flow is modulated using a primary electrostatic image formed on the outer surface of a photosensitive screen with a large number of openings stretched over a rotating drum-shaped frame, and the ion flow moves in sync with the drum-shaped frame. In an electrostatic recording device that forms a secondary electrostatic image by projecting a particle stream from a charged particle source onto the surface of a chargeable member, the drum-shaped frame is rotatably supported at a constant distance from the photosensitive screen. An electrostatic recording device comprising means for fixing the charged particle source at a predetermined position using magnetic force acting between the inside and outside of the drum-shaped frame.