JPS63292162A - Color recording method - Google Patents

Abstract

PURPOSE:To execute copying at high speed by a small-sized machine, and to easily perform switching of colors of a recording image, by selecting suitably the polarity of a toner in each developing device, and changing the combination of colors of the recording image. CONSTITUTION:Between an electrostatic latent image potential 21 of a black part B and a background potential 22, a developing bias 25 is set, and by a first developing device 5, the development is executed by using a black toner of a positive electrification. Thereafter, by a second electrifier 15, a photosensitive body 1 is brought to a positive electrification uniformly again, and in this case, a scorotron is used for the second electrifier 15, and the grid potential of the scorotron is set to the potential being roughly equal to the potential 22 of the electrostatic latent image of the background part. In a second exposing part 20, a second electrostatic latent image corresponding to a red part R is formed, and by a second developing device 6, said latent image is developed by using a red toner of a positive electrification. In this case, the developing bias potential 27 is set between the background potential 22 and the electrostatic latent image potential 26 of the red part. In such a way, toner images of two colors are formed on the photosensitive body 1, and these toner images are transferred to a recording form 12 at a stretch. In such a way, there is no reduction of a copying speed, and switching of the color can be executed easily.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a color recording method for recording a color image on recording paper using an electrophotographic recording method.

``Prior Art'' In the conventionally well-known electrophotographic recording method, a photoreceptor is uniformly charged, and a light image is formed on the photoreceptor for exposure, thereby forming an electrostatic latent image. After that, the electrostatic latent image is developed to form a corresponding toner image, and the toner image is transferred onto recording paper.

Various methods for recording color images using such electrophotographic recording methods have been developed as described below.

First, FIG. 6 shows a schematic diagram of the so-called overlap transfer method.

In this method, the photoreceptor is charged, exposed, developed, and transferred multiple times. For example, the first time is a black image, the second time is a red image, and the third time is a blue image. In this method, an electrostatic latent image corresponding to an image of a certain color is formed, and development and transfer thereof are repeatedly performed using toner of a corresponding color (Japanese Patent Application Laid-Open No. 61-488'71).

This device includes a Briclean corotron 2, a cleaning device 3, a charger 4, and a first developer 5 on the outer periphery of a photoreceptor 1.
, a second developing device 6, a third developing device 7, and a transfer device 8 are arranged. Furthermore, an exposure section 10 is provided between the charger 4 and the first developer 5. Furthermore, photoreceptor 1
A hollow transfer drum 9 is disposed so as to be circumscribed by the transfer portion 11 . The recording paper 12 is wound around the transfer drum 9 and repeatedly passes through the transfer section 11 as the transfer drum 9 rotates.

In this apparatus, first, when a black image is exposed, the electrostatic latent image is developed by a developing device 5 containing black toner. The toner image is transferred onto recording paper 12 by transfer section 11 . Next, a red image is exposed, and the electrostatic latent image is developed by a developing device 6 containing red toner. The toner image is transferred by the transfer unit 11 onto the recording paper 12 that has been wrapped around the transfer drum 9 once. Similarly, when the blue toner image is transferred onto the recording paper 12, the recording paper 12 is released from the transfer drum 9 and heads toward the fixing device 13. In this way, a total of three color images can be recorded.

However, in an apparatus with such a configuration, the space for installing the transfer drum 9 is relatively large, which leads to an increase in the size of the apparatus.Also, the process from exposure to transfer is repeated for the number of colors used, resulting in a slow copying speed. The problem is that it is late.

FIG. 7 shows a schematic diagram of an apparatus employing a different sequential transfer method.

In this method, a separate photoreceptor is prepared for each color, and the charging, exposure, development, and transfer of the photoreceptor are performed in separate steps.For example, the first step is to create a black image, and the second step is to create a red image. This is a method of sequentially transferring data onto recording paper 12 (Japanese Patent Application Laid-Open No. 1983-1999)
-36767).

In this device, a Briclean corotron 2, a cleaning device if3, a charger 4, and a black toner developer 5 or a red toner developer 6 are arranged around the outer periphery of each photoreceptor 1. Furthermore, exposure sections 10 and 20 are provided between the charger 4 and the developer 5 or 6, respectively. Furthermore, a transfer device 8 is arranged below each photoreceptor 1.

The recording paper 12 has two transfer parts 11a in the direction of the arrow in the figure;
llb to the fixing device 13.

In this way, a total of two color images can be recorded.

Although an apparatus having such a configuration does not have the disadvantage that the copying speed is slow, it has the disadvantage that the apparatus becomes larger because a plurality of photoreceptors 1 and the like are provided for each color.

Furthermore, in both of the above two methods, toner images of different colors are superimposed on the recording paper, so if the transfer position is not aligned accurately during the second and subsequent transfers, color misregistration will occur, resulting in so-called high precision. It also has the disadvantage of requiring registration.

Now, FIG. 8 shows a schematic diagram of an apparatus employing the so-called overlapping development method (Japanese Patent Application Laid-Open No. 124354/1983).

This device includes a Briclean corotron 2, a cleaning device 3, a charger 4, a first developer 5, a second developer 6, a pre-transfer corotron 14, and a transfer device 8 on the outer periphery of the photoreceptor 1.
and are arranged. Also, a charger 4 and a first developer 5
A first exposure section 10 is provided between the first developing unit 5 and the first developing unit 5.
A second exposure section 20 is provided between the first developing device 6 and the second developing device 6 .

In this device, after uniformly charging the photoreceptor 1, an electrostatic latent image is formed with positive polarity in the first exposure section 10, and an electrostatic latent image with negative polarity is formed in the second exposure section 20, based on the charged potential. Electrostatic latent images are formed and developed with different colored toners of different polarity. In this way, two-color toner images are formed on the photoreceptor 1, and these toner images are transferred to the recording paper 12 all at once.

Since this method develops a two-color image by forming a so-called ternary latent image, there is no reduction in copying speed, and there is no need for highly accurate registration.

However, there is an upper limit to the charging potential of the photoreceptor, and when that potential is divided into two and charged to opposite polarities, the potential contrast of both the first electrostatic latent image and the second electrostatic latent image is The problem was that it was half of the normal amount. moreover,
In order to carry out such exposure, a special photoreceptor must be used, and there is also the drawback that it requires modulation of the energy of the light.

On the other hand, FIG. 9 shows a schematic configuration diagram of an apparatus employing a color recording method using a similar overlapping development method but forming a latent image using a different method.

This device includes a Briclean corotron 2, a cleaning device 3, a first charger 4, a first developer 5, a second charger 15, a second developer 6, A pre-transfer corotron 14 and a transfer device 8 are arranged. Also,
A first exposure section 10 is provided between the first charger 4 and the first developer 5, and a first exposure section 10 is provided between the first charger 4 and the second developer 6.
A second exposure section 20 is provided between the two.

In this device, after the photoreceptor 1 is uniformly charged by the first charger 4, an electrostatic latent image is formed in the first exposure section 10, and the first developer 5 uses, for example, black toner to form an electrostatic latent image. Develop. Next, after the photoreceptor 1 is uniformly charged again by the second charger 15, an electrostatic latent image is formed in the second exposure section 20, and a second
The image is developed using, for example, a red toner in a developing device 6. In this way, two-color toner images are formed on the photoreceptor 1, and these toner images are transferred to the recording paper 12 all at once.

This method also does not reduce copying speed and does not require high lit registration.

"Problems to be Solved by the Invention" By the way, the copying functions of copying machines and the like have become increasingly sophisticated and complex, and improvements have been made to meet the diverse needs of users.

For example, for a document with a black or red image drawn on a white background, there is a request to make the background part red and the image part black. There is also a demand for making the image area white.

In an apparatus that employs the overlapping development method as described above, when the configuration is fixed such that the first electrostatic latent image is developed with black toner and the second electrostatic latent image is developed with red toner. , it is difficult to respond to such requests immediately.

If such a request is to be met, it is actually necessary to replace the toner in the first developing device and the second developing device with toner of the requested color. However, such work is extremely complicated and lacks convenience.

The present invention has been made with attention to the above points, and provides a color recording method that uses the overlapping development method to enable compact and high-speed copying, and also allows easy switching of the colors of recorded images. The purpose is to

"Means for Solving the Problems" The color recording method of the present invention performs a first charging process on a photoreceptor, forms a first electrostatic latent image thereon, and converts the electrostatic latent image into Developing to form a first toner image, followed by a second toner image.
The electrostatic latent image is formed using a toner of a different color from the first toner, and the first developing device and the second developing device are both The pair of developer supply sections contain toner of the same color with different frictional charging polarities, and the first development device and This method is characterized by selecting a combination of toner polarities in the second developing device.

"Operation" In the above method, when the color of the recorded image is selected, which friction charge polarity toner is to be used in each developing device is selected accordingly.

For example, if a negative latent image is formed on a positively charged photoreceptor and this is developed with positively charged toner, the toner will adhere to the image area.
If the image is developed with negatively charged toner, the toner will adhere to the background □ area.

In the former case, normal development is performed, but in the latter case, so-called white-out development is performed. By selecting and combining such functions for the first developing device and the second developing device, various recorded images can be obtained.

“Example” 1st r! A shows a schematic configuration diagram of an apparatus suitable for carrying out the color recording method of the present invention.

This device includes a pre-clean corotron 2, a cleaning device 3, a first charger 4, a first developer 5, a second charger 15, a second developer 6, A pre-transfer corotron 14 and a transfer device 8 are arranged. Also,
A first exposure section 10 is provided between the first charger 4 and the first developer 50, and a first exposure section 10 is provided between the first charger 4 and the second developer 6.
A second exposure section 20 is provided between them. The recording paper 12 is sent out from the paper feed tray 16 and transferred to the transfer device 8.
and the photoreceptor 10, and is discharged via the fixing device 13.

Further, the first developing device 5 includes a developing roll 5a that develops the electrostatic latent image on the photoreceptor 1, and a pair of developer supply sections 5b that supplies toner to the developing roll 5a.

It has 5C. Developing brushes 5d and 5e that stir the developer and bring it into contact with the developing roll 5a are housed in the developer supply units 5b and 5c. In this example,
One developer supply section 5b contained black toner having positive frictional charging polarity.

Further, the other developer supply section 5C contained black toner having negative friction charge polarity.

Similarly, the second developing device 6 includes a developing roll 6a that develops the electrostatic latent image on the photoreceptor 1, and a pair of developer supplies 16b that supplies toner to the developing roll 6a.

It has 6C. Developing brushes 5d and 5e that stir the developer and bring it into contact with the developing roll 6a are housed in the developer supply units 6b and 6c.

In this embodiment, one developer supply section 6b contained red toner having positive frictional charging polarity. Also,
The other developer supply section 6c contained red toner having negative friction charge polarity.

The developing rolls 5a, 5a of both developing devices are made of rotatable non-magnetic cylindrical sleeves, contain magnets therein, and are used to guide magnetic carriers in the developer to the photoreceptor 1. . This is a device that performs so-called two-component development.

Note that in each developing device 5.6, a pair of developer supply sections 5
Only one of b, 5c, 5b, and 5c is selected and used, but when switching between them, the rotation of the developing brushes 5d, 5e, 6d, and 6e of the unused developer supply section is stopped. , the developing rolls 5a and 6a are idled for an appropriate period of time. This is performed while the developing rolls 5a, 5a are in contact with the non-image area of the photoreceptor 1 during preparation for the recording operation.

In addition, the first exposure section 10 and the second exposure section 20 of this apparatus include a so-called imaging optical system using a mirror or lens system, a laser diode array, a light emitting diode array, a liquid crystal shutter array, a fluorescent display element, etc. A so-called optical writing device such as an array is used.

Various embodiments of the color recording method of the present invention will now be described with reference to FIGS. 2 and 3.

Here, as shown in the upper part of the figure, the original has a white background (W), a black area (B), and a red area (R). 1st
The illustrated embodiment is an example in which a copy is made in the same color as a normal original.

First, the photoreceptor 1 is uniformly positively charged by the first charger 4 (FIG. 2a).

Next, in the first exposure section 10, the photoreceptor 1 is exposed to negative light. As a result, the photoreceptor 1 is neutralized at the black end (FIG. 2b). In this embodiment, light emitting diode arrays capable of processing image signals of arbitrary colors and performing exposure were employed in both exposure sections.

Next, a developing bias 25 is set between the electrostatic latent image potential 21 of the black portion B and the background potential 22, and development is performed using positively charged black toner in the first developing device 5. As a result of this development, toner adheres to the areas where the potential of the electrostatic latent image is low (the areas corresponding to the black areas) (FIG. 2C).

After the first development is completed, the photoreceptor 1 is uniformly and positively charged again by the second charger 15 (FIG. 2d).

In this case, a scorotron is used as the second charger 15. The grid potential of this scorotron is set to approximately the same potential as the potential 22 of the electrostatic latent image in the background.

Thereafter, a second electrostatic latent image corresponding to the red portion R is formed by negative exposure in the second exposure section 20 (FIG. 2e). This is developed using positively charged red toner in the second developing device 6 (FIG. 2f). At this time, the developing bias potential 27 is
It is set to be between the background potential 22 and the red electrostatic latent image potential 26. In this way, two-color toner images are formed on the photoreceptor 1, and these toner images are transferred to the recording paper 12 all at once.

Needless to say, this method does not reduce the copying speed and does not require highly accurate registration.

Next, according to Figure 3, on the white background (W>), the black area (B) and the red area (
An example will be shown in which, when copying a document having R), recording is performed in which the white background part is made red, the black part image is black, and the red part image is made white. The configuration of the apparatus is the same as that used in the implementation of FIG.

First, the photoreceptor 1 is uniformly positively charged by the first charger 4 (FIG. 3a). Next, in the first exposure section 10, the photoreceptor 1 is exposed to negative light. As a result, the photoreceptor 1
Static electricity is removed in black area B (Fig. 3b).

Next, a developing bias 25 is set between the electrostatic latent image potential 21 of the black portion B and the background potential 22, and development is performed using positively charged black toner in the first developing unit 5 (the third Figure C).

This time, uniform charging by the second charger 15 will be omitted. Thereafter, an electrostatic latent image corresponding to the red portion R is formed by negative exposure in the second exposure section 20 (FIG. 3d).

Further, the second developing device 6 performs development using negatively charged red toner (FIG. 3e). Developing bias 2 at this time
2 is set to an intermediate value between the electrostatic latent image potential 26 corresponding to the red IR and the background block potential 22.

As a result, the white part (W) is red, the black part (B) is black,
A recorded image with white areas in red is obtained.

Next, red toner is stored in each of the developer supplies 15b and 5C of the first developing device 5, and each of the developer supplying portions 6b and 5C of the second developing device is filled with red toner.
An embodiment in which various types of recording are carried out by storing black toner in 6c will be described with reference to FIGS. 4 and 5.

In addition, in the case of Figures 4 and 5, the manuscript also has a white background (W).
An image with black parts (B) and red parts (R) is used.

In FIG. 4, first, the photoreceptor 1 is uniformly positively charged by the first charger 4 (FIG. 4a). next,
Located right in the first exposure section 10, the photoreceptor 1 is exposed to negative light. As a result, the photoreceptor 1 is neutralized at the Kurobe area (
Figure 4b).

Next, a developing bias 25 is set between the electrostatic latent image potential 21 of the black portion B and the background potential 22, and development is performed using negatively charged red toner in the first developing device 5. As a result of this development, red toner adheres to a portion of the background potential 22 corresponding to the white background, and development is performed (FIG. 4C).

Next, recharging by the second charger 15 is omitted, and a second electrostatic latent image corresponding to the red area R is formed by negative exposure in the second exposure section 20 (FIG. 4d).

This is developed using positively charged black toner in the second developing device 6 (FIG. 4e). At this time, the developing bias potential 27
is set between the background potential 22 and the red electrostatic latent image potential 26. In this way, two-color toner images are formed on the photoreceptor 1, and these toner images are transferred to the recording paper 12 all at once. Note that, before this transfer, both the black toner and the red toner are charged to the same polarity by the pre-transfer corotron 14.

Through the above process, a recorded image with a red background and a black image area is obtained.

On the other hand, in the embodiment shown in FIG.
The photoreceptor 1 is uniformly positively charged by the charger 4 (FIG. 5a).

Then, in the first exposure section 10, the photoreceptor 1 is exposed to negative light. As a result, the photoreceptor 1 is neutralized at the Kurobe area (FIG. 5b).

Next, a developing bias 25 is set between the electrostatic latent image potential 21 of the black portion B and the background potential 22, and development is performed using negatively charged red toner in the first developing device 5. As a result of this development, red toner adheres to the white portion of the background potential 22 and development is performed (FIG. 5C).

After the first development is completed, the photoreceptor 1 is uniformly and positively charged again by the second charger 15 (FIG. 5d).

In this case, a scorotron is used as the second charger 15. The grid potential of this scorotron is set to approximately the same potential as the potential 22 of the electrostatic latent image in the background.

Thereafter, a second electrostatic latent image corresponding to the red area R is formed by negative exposure in the second exposure unit 20 (FIG. 5e). (FIG. 5f). At this time, the developing bias potential 27 is set between the background potential 22 and the red electrostatic latent image potential 26. In this way, the two colors are formed on the photoreceptor 1. Toner images are formed, and these toner images are transferred to the recording paper 12 all at once.

Note that, before this transfer, both the black toner and the red toner are charged to the same polarity by the pre-transfer corotron 14. In this case, a recorded image is obtained in which the background part is the base, the black part is white, and the red part is black.

In addition, in the above embodiment, the specific structure of each part was selected as follows.

<In the case of examples> ☆Photoreceptor ・Se (selenium) type photoreceptor ・Drum diameter 200mm ☆First developer ・Two-component ferrite carrier.

Average particle size: 100 μm ☆Second developer/carrier A magnetic powder dispersion type obtained by mixing 35 parts of styrene-n-butyl methacrylate copolymer and 65 parts of magnetite, melting and kneading, and then finely pulverizing the mixture. Average particle size is 30 μm 1 density is 2.2
g/am3°/black toner (negatively charged) 92 parts of styrene-n-butyl methacrylate copolymer and 8 parts of carbon black #4000 (manufactured by Mitsubishi Chemical Corporation),
The mixture was mixed with 2 parts of a charge control agent (Bontron P-51, manufactured by Orient Chemical Co., Ltd.), melted and kneaded, and then finely pulverized to an average particle size of 12 μm. Charges negatively with respect to the carrier.

・Black toner (positively charged) 92 parts of styrene-n-butyl methacrylate copolymer and 8 parts of carbon black #4000 (manufactured by Mitsubishi Chemical Corporation),
The mixture was mixed with 2 parts of a charge control agent (Bontron 5-34, manufactured by Orient Chemical Co., Ltd.), melted and kneaded, and then finely ground to an average particle size of 12 μm. Charges positively to the carrier.

・Red toner (negatively charged) 92 parts of styrene-n-butyl methacrylate copolymer, 8 parts of red pigment Resource Cult (BASF), and 2 parts of a charge control agent (E-84, manufactured by Orient Chemical Co., Ltd.) were mixed and melted. After kneading, the average particle size is 12
Finely ground to μm.

Charges polarity to the carrier.

・Red toner (positively charged) 92 parts of styrene-n-butyl methacrylate copolymer, red pigment Resource Cult (BASF) 8w6, and 2 parts of cetylpyridinium chloride as a charge control agent were mixed and melted and kneaded to produce an average particle size of 12μ.
Finely ground to m. Charges positively to the carrier.

☆Process speed 150mm/sec ☆Development parameters (first developer and second developer) TG (trimming gap) 9.9mm DR3 (drum roll space) 1, Qmm MSA (magnetic pole tilt) +5°Vd (Developing roll rotation speed) 450 mm/sec Main pole of magnetic pole 50G Developing roll rotation WITH (in forward direction with photoconductor) "Modification" The above example shows an example in which the photoconductor is positively charged in each charger. However, the same effect can be obtained even if the photoreceptor is charged.

Further, the configuration of the exposure section and the developing method of each developing device may be freely selected.

"Effects of the Invention" According to the color recording method of the present invention described above, the color combination of the recorded image can be changed by appropriately selecting the toner loss characteristics in each developing device, so it can meet the various demands of users. can.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a recording apparatus suitable for carrying out the color recording method of the present invention, and FIGS. 2 to 5 are explanatory diagrams of the potentials of various parts of the photoreceptor showing examples of the color recording method of the present invention.
6 to 9 are schematic diagrams of an apparatus employing a conventional color recording method. 1... Photoreceptor, 21.22... Potential of toner image, 23...
...Background potential. Applicant: Fuji Xerox Co., Ltd. Agent

Claims (1)

[Claims] A first charging process is performed on the photoreceptor, a first electrostatic latent image is formed thereon, the electrostatic latent image is developed to form a first toner image, and then a second toner image is formed. An electrostatic latent image is formed, and the electrostatic latent image is developed using a toner of a different color from the first toner, wherein both the first developing device and the second developing device are one and the same. It has a developing roll and a pair of developer supply parts,
The pair of developer supply units contain toners of the same color having different frictional charging polarities, and a combination of toner polarities in the first developer and the second developer is selected depending on the content of the recorded image. A color recording method characterized by: