JPS6365934B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of copying an inverted image having a negative relationship with a light image of an original using a photoreceptor.

2. Description of the Related Art Conventionally, a method of obtaining a copy of an inverted image that has a negative relationship with an original image is known. In this method, a photoreceptor made of a photoconductor is used, and the photoreceptor is primarily charged to, for example, positive polarity. Next, exposure is performed using the original optical image to form an original optical image, that is, a positive electrostatic latent image corresponding to the original image, on the photoreceptor.
On the photoreceptor on which this positive electrostatic latent image has been formed, the non-positive electrostatic latent image area is visualized with toner of the same polarity, that is, positive polarity, and reverse development is performed, and this reversed image is transferred to transfer paper. be done. In such a conventional method, for example, as shown in FIG. 1, when the photoreceptor 1 is exposed to light with an original 0 having a black image on the background, a positive electrostatic latent image 2 is formed in the image-corresponding area; The toner adheres to the area 3, that is, the skin corresponding area 3.
However, this toner does not adhere in accordance with the charge density on the photoreceptor, but adheres in accordance with the intensity of the surface electric field due to the bias potential applied during development. That is, the electric field strength at the edge portion 301 of the background corresponding area 3 which is close to the positive electrostatic latent image 2 having a large difference in charge density becomes relatively large, and a large amount of toner adheres intensively to the edge part 301 of the background corresponding area 3. The other portions 302 are unevenly developed with almost no adhesion. When such a toner-based inverted image is transferred to transfer paper, the inverted image corresponding to an original image consisting of thin lines or dots is well reproduced, but the inverted image corresponding to an original image with many wide and uniform areas is reproduced well. In this case, only the portion close to the black image corresponding portion of the original was copied with high density, and a completely reversed image could not be obtained.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for copying a reversed image by which a reversed image copy having a completely negative relationship with an original image can be obtained.

This invention uses a photoreceptor, forms a positive mask consisting of a toner image corresponding to the original optical image on the photoreceptor surface of the photoreceptor, and uses this positive mask to create an inverted image with toner that has a negative relationship with the original optical image. and is configured to transfer this onto transfer paper to obtain a copy of the inverted image.

According to this invention, it is possible to create a negative electrostatic latent image for creating a reversal image that has a negative relationship with the optical image of the original by using a positive mask consisting of a toner image, and then it can be completely reversed by normal development and transfer. You can get the image.

The present invention will be described below with reference to the accompanying drawings. Second
The figure shows a step explanatory diagram of a reverse image copying method as an embodiment of the present invention. The photoreceptor 4 used here is made of selenium as a photoconductor, and is stacked in a plate shape on a conductive substrate 6 to form a photoreceptor surface 5. This photoreceptor 4
is made into a conductor when the photosensitive surface 5 is irradiated with light, and supplies and discharges charges between it and the conductive substrate 6.

First, the photoreceptor 4 is uniformly charged to a positive polarity by the primary charger 7, as shown in FIG. 2A.
Subsequently, the photoreceptor 4 is irradiated with a light image from the original 8 to perform exposure. This document 8 has a white background portion 801 and a black portion 802 forming an image. In the photoconductor 4 exposed to the light image of the original 8, the photoconductor region 401 corresponding to the background section 801 is made conductive and the positive charge on the photoconductor surface 5 is dissipated, but the black section 8
The photoreceptor region 402 corresponding to 02 is not irradiated with light and maintains a positive charge. Therefore, a positive electrostatic latent image is formed on the photoreceptor, and this is developed with black toner 9 having a negative polarity charge, and a light image of the original, that is, a toner image corresponding to the original image is developed on the photoreceptor surface 5. (See Figure 2 C). Use this toner image as a positive mask 10
used in subsequent steps as As shown in FIG. 2D, the photosensitive surface 5 covered with the positive mask 10 is completely neutralized. In this case, the static eliminating lamp 11 and the static eliminating charger 12 that discharges a positive corona having the same polarity as the primary charge are operated, the static eliminating lamp 11 makes the photoreceptor 4 conductive, and the synergistic action of this and the static eliminating charger 12 causes the background to become The charges remaining in the corresponding area 401 are dissipated. In the black corresponding area 402, the black toner 9 is positively charged by the neutralizing charger 12, the photosensitive surface 5 below the black toner 9 becomes conductive due to the light passing through the toner layer, and the latent image charge disappears. In the case of the selenium photoreceptor, at this time, not only the latent image charge disappears, but also a negative charge is generated on the lower photosensitive surface 5 of the black toner, induced by the positive charge of the black toner 9. In this case, depending on the amount of black toner 9, resistance value, intensity of corona discharge, and intensity of static elimination light,
The amount of negative charge changes, and if the amount of black toner 9 is small and simply acts as a high resistance, and the amount of corona discharge and the intensity of the static eliminating light are insufficient, positive charge may be present on the photosensitive surface 5. be. Therefore, the black toner image as the positive mask 10 has a large amount of toner,
It is also desirable that the intensity of the corona discharge and the intensity of the static eliminating light be set to a predetermined value or higher. After that, as shown in FIG. 2E, the photosensitive surface 5 is covered with a positive mask 10.
is charged by a secondary charger 13 to which a positive voltage is applied. At this time, the charge on the lower photosensitive surface 5 of the black toner 9 serving as a positive mask hardly moves and maintains the polarity at the time of charge removal. Next, Cleaner 14
The black toner 9 on the photosensitive surface is removed by this. As a result, a negative electrostatic latent image 15 is formed on the photosensitive surface 5 in a negative relationship with the original image. Thereafter, the negative electrostatic latent image 15 is developed with the black toner 9 having the same negative charge as that used in the positive mask creation process, but at this time, the background corresponding area 401 has a positive charge due to secondary charging. Uniformly distributed, black corresponding area 4
Negative charges of the same polarity as the black toner 9 remain in the toner 02. Therefore, the background corresponding area 401 uniformly attracts the black toner 9, and the black corresponding area 402 repels the black toner 9, so that the original light image, that is, the inverted image 16 which has a negative relationship with the original image, becomes black. An image is visualized on the photosensitive surface 5 by the toner 9 (see FIG. 2-G). Thereafter, a transfer paper 17 is brought close to the photoreceptor 4, and a black toner image is transferred using a corona transfer charger 18. The inverted image 16 transferred to the transfer paper 17 is made into a permanent image by a well-known fixing device (not shown).

The copy of the inverted image 16 created in this manner has no stains caused by the black toner 9 in the background portion, that is, the portion corresponding to the black portion 802 of the original image, and is a perfect inverted image 16 of the original image.

In particular, the wide and uniform density of the inverted image has the advantage that both edge portions and other portions are copied with uniform density.

If you copy a negative original image again using the inverted image copying method shown in Figure 2,
It is clear that positive images can be created.

In the above-mentioned place, after the positive mask creation process,
Although a static elimination operation is performed (see FIG. 2D), this static elimination operation may not be performed if it is necessary to simplify the copying process. Furthermore, although both the static elimination lamp 11 and the static elimination charger 12 are used in this static elimination operation, only the static elimination charger 8 or only the static elimination lamp 11 may be used.

In the reversal image copying method shown in FIG. 2, a photoconductor 4 made of selenium was used as a photoconductor, but instead of this, a boss charge photoconductor (hereinafter simply referred to as photoconductor) 19, which can be charged at both poles, is used. A method of copying an inverted image using the following will be described below.

First, the photoreceptor 19 is uniformly charged to a negative polarity by the primary charger 20, as shown in FIG. 3A. Subsequently, the photoreceptor 19 is exposed by being irradiated with a light image from the same document 8 as shown in FIG. 2 (see FIG. 3B). As a result, the photoreceptor region 191 of the photoreceptor 19 corresponding to the background portion 801 of the original becomes a conductor and the negative charge on the photoreceptor surface 5 is dissipated.
The photoreceptor region 192 corresponding to 02 is not irradiated with light and maintains a negative charge. As a result, a positive electrostatic latent image consisting of a negative charge is formed on the photoreceptor 19, and this is developed with the black toner 21 having a positive charge.
A toner image corresponding to the original image is formed as a positive mask 10 (see FIG. 3C). As shown in FIG. 3D, the photosensitive surface 5 covered with the positive mask 10 is
It is charged by a secondary charging charger 22 to which a positive potential having a polarity opposite to that of the secondary charging is applied. At this time, the negative charge applied during the primary charging continues to remain on the photosensitive surface 5 below the black toner 21 as the positive mask 10. This is because the black toner 21 acts as a capacitor so that the positive charge applied to the upper side through the black toner 21 continues to maintain the negative charge on the lower side, that is, the photosensitive surface 5. It's for a reason. After this, the black toner 21 adhering to the photosensitive surface 5 is removed by a cleaner 14. As a result, a negative electrostatic latent image 15 is created on the photosensitive surface 5 in a negative relationship with the original image. This negative electrostatic latent image 15 is formed by the same positive charges as shown in FIG. 2, and is subsequently developed and transferred in the same process as shown in FIG. 2 using the same negative polarity black toner 9. An inverted image is obtained (see Fig. 3-7).

In the inverted image copying method shown in Figure 3, the polarity of primary charging and secondary charging is changed, so the static elimination operation to dissipate the residual charge due to primary charging, which was performed prior to secondary charging, is The advantage is that it is not required. However, since the black toner 21 for creating the positive mask 10 and the black toner 9 for creating the inverted image that will become a permanent image have different polarities, two developing devices are required.

Although the case where black toner 9 is used for creating a reversed image has been described above, it is of course possible to use red toner or other color toner instead. In this case, a toner of a predetermined color may be substituted for the toner for creating the positive mask 10. Furthermore, in some cases, the toner for creating a positive mask and the toner for creating a reverse image may be combined in different colors.

An example of the copying device 23 used in the reverse image copying method shown in FIG. 2 will be described with reference to FIG. 4.

This copying device 23 has a photosensitive drum 24 rotatably arranged in the center.
A method is adopted in which one copy is obtained every two revolutions. On the circumference of the photosensitive drum 24, a photosensitive member 4 made of selenium is superimposed on the outer circumferential surface of the drum body as a conductive base 6. Around this photosensitive drum 24, a primary charger 7 to which a positive voltage is applied, an exposure device 25 that irradiates the photosensitive surface 5 with an optical image of the original, and a black toner 9 having a negative charge.
a developing device 26 that supplies the photosensitive surface 5 with a magnetic brush, a static eliminator that is a combination of a static eliminating lamp 11 and a static eliminating charger 12, and a secondary charging charger 13 to which a positive voltage of the same polarity as the primary charging charger 7 is applied. ,
The transfer charger 27, the cleaner 14, and the static elimination charger 28 are arranged in this order along the rotation direction A of the photosensitive drum 24.

In order to obtain a copy of an inverted image using the copying device 23, the photoreceptor 4 is first rotated at a constant speed.
The photoreceptor 4 has its photoreceptor surface 5 subjected to a primary charger 7.
As a result, the entire surface is uniformly charged with a positive charge. Subsequently, the document is exposed to a light image to form a positive electrostatic latent image. This latent image is developed by a developing device 26, and a toner image corresponding to the original optical image is formed on the photosensitive surface 5 as a positive mask 10. In this state, the photoreceptor 4 is neutralized by the static eliminating lamp 11 and the static eliminating charger 12.
Subsequently, the secondary charging charger 13 charges the battery with a positive charge. Thereafter, the toner image on the photosensitive surface 5 is removed by a cleaner 14, and a negative electrostatic latent image 15 for forming a reversal image is created on the photosensitive member 4. When forming the negative electrostatic latent image 15, the transfer charger 27 and the static elimination charger 28 are controlled by a switch (not shown) so as to be kept in a stopped state. The photosensitive drum 24 continues to rotate for the second time. When the second rotation starts, the primary charging charger 7, the exposure device 25, the static elimination lamp 11, and the static elimination charger 12 are controlled by a switch (not shown) and kept in a stopped state.
The photosensitive surface 5 having the negative electrostatic latent image 15 is transferred to the developing device 26.
The inverted image 16 is created using the black toner 9. This inverted image 16 is formed on the photosensitive drum 24.
Transfer paper 1 is conveyed in synchronization with the rotational speed of
7, the image is transferred by static electricity generated by the transfer charger 27. The transferred reverse image 16 is converted into a permanent image by a fixing device 32, and a copy of the reverse image is created. On the other hand, the photosensitive surface 5 that has passed through the transfer charger 27 is cleaned of residual toner by the cleaner 14, and is completely neutralized by the charger 28, and then subjected to the next copying process.

Since this copying device 23 uses only one developing device 26, it is effective for downsizing the device, and the copying device 23 can copy an inverted image with uniform image density using the normal developing device 26.
It can be obtained by developing it.

As described above, according to the reversed image copying method to which the present invention is applied, a document image can be created as a completely reversed image, and it is effective for creating copies of various patterns using tasteful reversed images.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a reversed image on a photoreceptor obtained by a conventional reversed image copying method, and FIGS. 2 and 3 are process explanatory diagrams of a reversed image copying method as different embodiments of the present invention. FIG. 4 is a schematic front view of a copying apparatus for carrying out a reverse image copying method as an embodiment of the present invention. 4...Photoconductor, 5...Photosensitive surface, 7...Primary charger, 8...Original, 9...Black toner, 10
... Positive mask, 11 ... Static elimination lamp, 12 ...
Static neutralization charger, 13... Secondary charging charger,
14...Cleaner, 15...Negative electrostatic latent image, 16
...Reverse image, 17...Transfer paper.

Claims (1)

[Scope of Claims] 1. Using a photoreceptor made of a photoconductor, the photoreceptor is sequentially charged with a primary charge, exposed to a light image of an original, and developed with toner, so that a toner corresponding to the optical image of the original is applied to the photoreceptor. A process of creating a positive mask consisting of an image, a process of secondary charging a photoreceptor covered with a positive mask, and then removing this positive mask to form a negative electrostatic latent image, and a process of forming a negative electrostatic latent image with toner. 1. A method for copying a reversed image, comprising the steps of developing a reversed image having a negative relationship with a light image of an original, and transferring the reversed image to transfer paper. 2. The reversal image forming method according to claim 1, wherein a static elimination step is performed before the photoreceptor covered with the positive mask is secondarily charged. 3. The reversal image forming method according to claim 2, wherein the static elimination step includes light irradiation and corona discharge.