JPS6045263A - Synthesized image copying method - Google Patents

Abstract

PURPOSE:To obtain a synthesized image copying method which is capable of forming easily a dichromatic or monochromatic synthesized picture by using not only a carrier but also a developer containing two kinds of toners whose electrifying characteristics are different from each other. CONSTITUTION:Triboelectrification is executed to a prescribed polarity by contact of a ferromagnetic material carrier of >=10<7>OMEGAcm resistance value and 25- 90mum average particle diameter, and a carrier. By contact of the first toner of >=10<12>OMEGAcm resistance value and 5-20mum average particle diameter, and the first toner, the triboelectrification is executed to the polarity opposite to said triboelectrification characteristic of the first toner, but with regard to the second toner of >=10<12>OMEGAcm resistance value and 5-20mum average particle diameter which is not electrified by contact to the carrier, a developer in which at least one of the first and the second toners has a magnetic property is used, and the first latent image, and the second latent image having the polarity opposite to said latent image or a different potential are developed, and thereafter, transferred to the surface of a transfer material.

Description

Detailed Description of the Invention Technical Field The present invention relates to a first toner that is tribo-electrified to a constant polarity by contact with a ferromagnetic carrier, and a first toner that is tribo-electrified by contact with the first toner. Although it is tribo-electrified to the opposite polarity, due to contact with the carrier G, it is tribo-electrified to be substantially the same f, L 17'142
A new fS from a mixture of at least three substances with a toner.
The present invention relates to a composite image copying method that can easily form two-color or monochrome composite images using S magnetic developer.

BACKGROUND ART In recent years, in response to the diversification of information processing, copying machines that enable composite image copying have been developed. Although the polarity is different f
The first and second latent images formed as a composite image are developed to form a toner image, and the toner image is transferred and printed. Copying machines that obtain copied images by transferring images onto a surface have come to be widely used.

As one of the above-described copying machines, the present inventors have already developed a system in which a positive image is exposed to light on the surface of a uniformly charged electrophotographic photoreceptor to form a first latent image, and a negative image is subsequently exposed to light. An electrophotographic copying machine has been invented which forms a second latent image and, as a result, forms a composite image. According to the electrophotographic copying machine according to the invention of the present inventors, it is possible to form a composite image without using a special photoreceptor or a pin electrode, and moreover, the formation of the composite image itself is easy. Therefore, it is extremely advantageous for its practical application.

By the way, with regard to the copying machine of the above type, it is often necessary to convert the first and second latent images into toner images using toners of different tones depending on the purpose of editing, identification, etc. In this case, Usually two developing devices are required;
As a result, it is inevitable that copying machines will become larger. Therefore, in order to eliminate such inconveniences, it is possible to convert the first and second latent images into toner images using toners of different tones using one developing device. It has been proposed to use a new developer consisting of a mixture of a magnetic carrier and two toners of different colors "A1", each triboelectrically charged to opposite polarities by contact with the magnetic carrier. However, if this developer is used in a copying machine of the above type, there will be problems such as fogging in the copied image and developer powder smoke inside the copying machine. Regarding the use of , there is a practical 1- major tS obstacle.

OBJECT OF THE INVENTION The object of the present invention is to avoid forcing the size of the copying machine as described above, and to avoid causing the disadvantages as described in [ff1i]. 2
It is an object of the present invention to provide a composite image copying method capable of converting a latent image into a toner image using toners of different tones.

SUMMARY OF THE INVENTION The gist of the present invention is that in the composite image copying method according to the present invention, when developing the first and second latent images, the resistance value lO7Ωan
2. A ferromagnetic carrier with an average particle size of 25 to 90 μIll, a resistance value of 10-2Ω6#7 that is frictionally charged to a constant polarity by contact with the carrier, and an average particle size of 5 to 20/71
Due to the contact between the first toner of No. 11 and the fIS1 toner, the first toner is frictionally charged to a polarity opposite to the frictional charging polarity of the first toner.
However, due to contact with the carrier, the resistance value of fS which is substantially triboelectrically charged is less than 1012Qα'-1 and the second toner having an average particle size of 5 to 20 μITI is at least 3
A magnetic developer is used in which at least one of the first and second toners is magnetic. f, (According to the analysis of the present inventors, the causes of the adverse effects that occur when using the developer that has already been proposed are the carrier in the abrasive developer and the triboelectric charging of the toner itself. It has been confirmed that there is instability in the toner21, and the present invention has been made based on the results of this analysis.The present invention has been developed by stabilizing the triboelectrification of the carrier and toner in the developer. The basic idea is to prevent the above-mentioned adverse effects from occurring.

Embodiment FIG. 1 is a drawing showing an example of a copying machine used to carry out the composite image copying method according to the present invention, and the arrow (
Electrophotographic photosensitive drum (1) rotationally driven in the a1 direction
is first uniformly charged to a predetermined polarity by the first scorotron charger (2), and then a light image corresponding to the positive original (3), that is, a positive image, is sequentially exposed via the optical system (4). be done. As a result, a first latent image is formed on the surface of the photoreceptor drum (1).

During this exposure, the document (3) is moved in the direction of arrow fb1 in synchronization with the rotation of the photosensitive drum (1).

The charger (2) has a corona electrode (2a) connected to a DC high voltage power supply (2b), and a DC bias power supply (2b).
2C) and a grid electrode (2d) provided between the corona electrode (2a) and the photoreceptor drum (1). It is uniformly charged to a potential approximately equal to the bias potential applied to the electrode (2d). Note that the charger for uniformly charging the surface of the photoreceptor drum (1) when forming the first latent image is not limited to a scorotron type charger such as the charger (2); type may also be used.

The second scorotron charger (5) is in the inlnl-
Similar to the case (2), the corona electrode (5a) connected to the DC high voltage power supply (5b) and the DC bias voltage 1 (5c)
The grid electrode (5d) is connected to the corona electrode (5a) and the photoreceptor drum (1).
), and the potential of the background portion of the first latent image formed as described above is set to be approximately equal to the bias potential applied to the grid electrode (5d). Note that the bias power source (5C) may be replaced with a constant voltage passive element such as a constant voltage diode, a discharge tube, or ZnR.

The light emitting diode (6) forms a second latent image by sequentially exposing a negative image to the surface of the photosensitive drum (1) on which the first latent image is formed as described above. A negative image responsive to electrical signals input from the image processing device is exposed onto the front surface. Regarding the formation of the second latent image, instead of the light emitting diode (6), a laser scanner,
OFT, liquid crystal array, etc. can be used as appropriate.

On the other hand, the magnetic brush developing roller (7) is for developing the first and second latent images based on a magnetic brush developing method using a magnetic developer (D), and is used at low speed in the direction of arrow A rotationally driven developing sleeve (7a) and a developer (De
) in the direction of the arrow fc1.The developing sleeve (7a) functions as a developing electrode and is powered by a DC bias power source ( 7C) is connected, and the developer (De
), two different types of toner are selectively attached. The developer (De) is made of a mixture of a ferromagnetic carrier and two different toners each triboelectrically charged to opposite polarities.

Further, the heavy electric corona charger (8) is used to align the polarity of the toner adhered to the surface of the photoreceptor drum (1) to the same polarity prior to transfer, and the transfer corona charger (9) is used to adjust the polarity of the toner adhered to the surface of the photoreceptor drum (1) to the same polarity before transfer. The obtained toner image is transferred onto the surface of transfer paper. A separation corona charger (10) is integrally attached to this charge (9) to separate the transfer paper on which the toner image has been transferred from the surface of the photoreceptor drum (1). There is. On the other hand, the cleaning blade (11) is used to remove developer remaining on the surface of the photoreceptor drum (1), and the eraser lamp (12) is used to erase charges remaining on the surface.

By the way, the composite image copying method according to the present invention includes the following steps: 3.5 Step @1 of forming a first latent image on the surface of the electrostatic latent image carrier; b. A second step of forming a second latent image of opposite polarity to the first latent image, or of the same polarity but different potential; A resistance value of 1012Ωα or more, which is triboelectrically charged to a constant polarity by contact with the body carrier and the carrier, and an average particle size of 5
The first toner having a thickness of ~20 μm is frictionally charged to a polarity opposite to the frictional charging polarity of the first toner due to contact with the first toner, but the resistance is not substantially +c frictionally charged due to contact with the carrier. The first toner is made of a mixture of at least three components including a second toner having a value of 1012ΩCIn or more and an average particle size of 5 to 20μin, and at least one of the first and second toners has magnetism.
a third step of developing the second latent image and applying the first and second toners to each latent image on the selected song to form a toner image; d;
) A fourth step of transferring the toner image from the surface of the electrostatic latent image carrier to the surface of the transfer material. As a result, the first and second
Synthetic duplication, just by changing the toner tone.

However, the first and second latent images can be formed into toner images using toners of different tones. In addition, in this case, disadvantages such as fogging in the copied image and developer powder smoke occurring in the copying machine are likely to occur.

fS Here, the fact that the second toner is not substantially tribo-charged by contact with the carrier means that it is determined by the so-called film development charge measurement method, that is, toner charge polarity (frictional charge polarity of @2 toner with respect to carrier). The surface of the insulating film, which is charged to the opposite polarity, is developed with a mixture of toner and carrier that has been sufficiently mixed and stirred, and the surface potential of the insulating film is reduced Jd that occurs at that time. The absolute value of the toner charge amount measured by the method of measuring the toner charge amount from the toner adhesion amount on the insulating film surface is 2.0 μc/g, preferably 1
．． It can be defined as 5 animals/g or less. However, if the amount of charge on the toner is extremely small, the toner will not adhere to the surface of the insulating film, making it impossible to measure the amount of charge on the toner itself. This also means that the toner can be charged.

On the other hand, the ferromagnetic carrier needs to have a resistance value of 107 Ω crn or more and an average particle size of 25 to 90 m. Here, the ferromagnetic carrier may be one consisting of single ferromagnetic particles, and if necessary, the surface of the ferromagnetic particles may be thinly coated with an insulating material such as resin. It's okay.

In addition, the 1.2 toner has a resistance value of 1o12Ωα or more,
In addition, it has an average particle size of 5 to 20 μm, and further,
It is necessary that at least one of them has magnetism with a low fS. The magnetic toner is produced by, for example, melting and mixing the resin and magnetic fine powder, cooling and pulverizing the mixture, and sorting the particle size. As the resin, polyethylene, polyacrylic acid ester, polymethyl methacrylate, polystyrene, styrene acrylic polymer, epoxy resin, coumaron resin, maleic acid resin, carbonic acid resin, fluoric acid resin, etc. can be used. As the fine powder, those having an average particle size of 0.1 to 5 μm such as FezOz, Fe3O4, and ferrite can be used.

However, it is important that the second toner is not substantially triboelectrified by contact with the ferromagnetic carrier, and for this purpose, the position on the triboelectrification series of the ferromagnetic carrier must be carefully considered. It is desirable to select the components accordingly. In addition, in order to electrostatically adhere the second toner to the first latent image, the frictional charging polarity of the second toner with respect to the first toner must be
It is necessary that the polarity is opposite to that of the first latent image.

Hereinafter, representative examples of many experiments conducted by the present inventors will be shown to clarify specific aspects of the composite image copying method according to the present invention.

[Experimental Example 1] In the copying machine shown in FIG.
After being uniformly charged to V, a positive image was exposed through the optical system (4) to form a first latent image with an image portion potential of H-1600V. After that, the photoconductor tram (1) is loaded by the charger (5).
At the same time, the non-image area is charged by the pestle and the non-image area is increased to 350 V, and the non-image area is exposed to light by the light emitting diode (6).
A latent image was formed.

Subsequently, the first and second latent images formed in this way are
Using the developer described below (referred to as developer I), use the developing roller (
7) to form a toner image and transfer it to the surface of the transfer paper to obtain a copy image.

In addition, during the development, the voltage value of the DC bias power supply (7c) is set to (+)400V, and the developing sleeve (
7a), a developing bias of (+) 400V was applied. In response to the fact that the potential of the non-image area of the photoreceptor drum (1) is (+) 350V, the value of this developing bias is set slightly higher than that, that is, on the potential side of the first latent image. It is slightly biased.

Here, developer I is a mixture of 3000 g of ferric oxide (average particle size 0.5 μm), 100 parts by weight zinc oxide (average particle size 0.1 μm), 40 parts by weight nickel oxide (average particle size 13 μm), and 17 parts by weight.
and 1195 g of water to form a slurry, and 98 g of a 25 ωt% aqueous solution of polymethacrylic acid sodium salt (Durban 7 manufactured by R.T. Pamplepilt) was added and mixed, and then spray-dried with an atomizer, and then By firing in air at 1190°C for 2 hours, ferrite [composition:
(NiO) 0.3 (ZnO) 0.7 (Fe2O3) 0.
85) and classified it to obtain an average particle size of 33
μm, ferromagnetic carrier 70ωt with resistance value 108Ωcm
Styrene acrylic polymer 100 parts by weight (Goodyear: Plaolite AC) Magnetic fine powder 20 parts by weight (Titan Kogyo: Magnetite RB-BL) Carbon black 8 parts by weight (Mitsubishi Kasei: MA#100) 17 ωt% magnetic toner (referred to as toner A) with an average particle diameter of 12 μm and a resistance value of 1014 Ωcm obtained by melting and mixing 2 parts by weight of charge control dye (manufactured by Orient Chemist: Nigrosine), cooling, crushing, and classifying; Styrene acrylic polymer (Plaolite AC) 100
Parts by weight Carbon black (MA #100) Obtained in the same manner from 8 parts by weight, average particle size 13 μm, resistance value 10
15Ωcm magnetic toner (referred to as toner B) 13ωt%
Toner A and Toner B are both black in color. Incidentally, the amount of charge of toners A and B on the magnetic ferromagnetic carrier (measured by the above-mentioned film development charge amount measuring method) is (+).
-12μc/g, (-)1.0μc/g.

The copied image obtained as a result of this experiment has sufficient image density and is of good image quality without fog, and faithfully reproduces the first and second latent images as a visible image. there were. Further, as confirmed during the experiment, there was hardly any occurrence of powder smoke from the developer around the developing roller (7), and there was no occurrence of the powder smoke inside the copying machine.

By the way, a detailed description of the phenomenon that occurs during development of an electrostatic latent image in this experiment is as follows. First of all,
When the first latent image is developed, the ferromagnetic carrier and the toner B corresponding to the second toner in the developer 1 are
Since the toner is frictionally charged to a (-) polarity by contact with the toner A, both of them tend to adhere to the image area of the first latent image having a potential of (+) 600V.

However, since the particle size of the ferromagnetic carrier is larger than that of toner B, and in addition, it is strongly magnetically attracted to the magnetic roller (7b) side, in reality, the ferromagnetic carrier is Only toner B will adhere to the image area without any adhesion to the image area.

On the other hand, when the second latent image is developed, toner A corresponding to the first toner in the developer I has a (+) polarity due to contact with each of the ferromagnetic carrier and toner B corresponding to the second toner. Because it is charged to (+), it is biased toward the (-) polarity side with respect to the developing bias of (+) 400V (+).
) It is electrostatically attracted and attached to the image area of the second latent image having a potential of 100V. Note that the potential of the non-image area is (+) 35 V for the developing bias (+) 400 V.
0V, it is biased toward the second latent image side, and an electrostatic force acts in the direction in which toner A adheres to the non-image area, but since toner A is a magnetic toner, the electrostatic force is opposite to this electrostatic force. Since the magnetic force in the direction is stronger, the toner A does not adhere to the non-image area.

According to the inventors' confirmation regarding the developer I, the components of the developer are a first component consisting of a carrier charged to (-) polarity and toner B, in terms of triboelectric charging characteristics. The toner is divided into two groups: the first group, and the second group consisting of toner A that is charged to the (+) polarity.Since triboelectric charging does not substantially occur within each group, the triboelectrification of each component is stable. I know that this will be done. This is particularly important in order to prevent fogging in copied images or developer powder smoke in the copying machine.
There is also a thing.

[Experimental Example 2] An experiment similar to Experimental Example 1 was conducted except that the developer described below (referred to as Developer 11) was used. As in Experimental Example 1, good fs results were confirmed. Here, the developer 11 is i
Obtained from 2Q ferromagnetic carrier 7oω[%,
Magnetic toner with average particle size of 11μm and resistance value of 1o14Ω (
(referred to as toner C) with an average particle size of 11. um, resistance value] o 15 Ωcm non-magnetic red toner (referred to as Toner R) from a mixture with 10 Ω [% r
Toner R corresponds to the first toner, and toner C corresponds to the second toner.

fS: In this developer H, unlike the case of developer I, the ferromagnetic carrier and toner C have polarity,
Toner R is (triboelectrified with polarity,
The first toner l corresponds to the toner R in the image area of the first latent image.
It becomes a tomoe that is attached as \.

In addition, the color tone of toner C is black, while the color tone of toner R is red.]-1 In the above experiment, the first latent image was a red developed image; The two latent images were each reproduced as a black developed image in different tones.

Incidentally, regarding the developer H, the amount of charge of toner C and toner R on the ferromagnetic carrier is (11.5 μc/g
, 1-115μ (7 g.
If the polarity is opposite to the one polarity of the latent image, the first. Although the state of toner adhesion to the second latent image is in a reverse relationship to that in Experimental Example 1, it can be seen that good experimental results can be obtained in the same manner as in the aforementioned Experimental Example.

[Comparative Experiment Example 1] In place of the toner C in the developer H, a developer mixed with toner A, which is triboelectrified to polarity by contact with the carrier, was used.
An experiment similar to Experimental Example 2 was conducted except that developer 11 consisting of a mixture of toner R12ω[% and toner R12ω[%] was used. Although the second latent image was reproduced, the image quality of the obtained copy image was poor, and the image was unsuitable for practical use, with a lot of image fog, especially red fog.Furthermore, during copying, the developer in the copying machine There was also significant dust smoke and developer scattering, and contamination from the developer inside the machine was noticeable.

Regarding these results, the inventors have confirmed that the carrier in developer III becomes polarized due to contact with toner 8, whereas the carrier in developer III becomes polarized due to contact with toner R.
Because it is triboelectrified in polarity, the charge that the carrier itself can hold is constantly unstable, and the amount of charge is only a small amount, so toner R is not electrostatically charged. It has been found that the main reason for this is that the toner R in particular is more likely to be separated from the developer ill.

It is clear from this experiment that the toner C in the developer 11, which corresponds to the second toner in the developer used in the composite image copying method according to the present invention, is a toner triboelectrically charged by contact with the carrier. In this case, good experimental results such as those in Experimental Example 1.2 can be obtained, and fi < fl
I understand that.

By the way, in relation to Experimental Example 1, an experiment similar to Experimental Example 1 was conducted by removing the ferromagnetic carrier or toner A from the developer 1, and found that in the former case, the Due to the significant decrease in the developer transportability and the significant decrease in the magnetic brush forming ability, only a copy image with unevenness and low image density was obtained, resulting in poor fS. In the latter case, although the ff1la image was developed well, the second latent image was not developed at all.

Effects of the Invention In the composite image copying method according to the present invention, the first and second latent images are developed with a resistance value of 107Ω or more and an average particle size of 5 to 90 μm.
m ferromagnetic carrier, and a first toner having an average particle size of 5 to 20 μm, which has a resistance value of 10"OCR or more, which is frictionally charged to a constant polarity by contact with the carrier, and A resistance value of 1012 Ω or more, which is triboelectrically charged to a polarity opposite to that of the toner, but is not substantially triboelectrically charged by contact with the carrier;
at least 3 with a second toner having an average particle size of 5 to 20 μn1
This is done using a magnetic developer that has low fS of at least one of the first and second toners. The first and second latent images can be formed into toner images using toners of different tones without forcing the size of a copying machine.

Regarding the magnetic developer, from the viewpoint of triboelectric charging characteristics, its components are classified into two groups: a first group consisting of carrier and second toner, and a second group consisting of fS from the first toner. Therefore, the triboelectric charging of the carrier and toner in the developer is stable, and in the composite image copying method according to the present invention, the disadvantages that occur when using previously proposed developers do not occur. I don't get it.

[Brief explanation of the drawing]

FIG. 1 is a drawing showing an example of a copying machine used to carry out the composite image copying method according to the present invention. De...Magnetic developer 1...Electrophotographic photosensitive drum 2...1st scorotron charger 3...Document table 6・Light emitting diode array 7・Developing roller 7a・-
・Developing sleeve 7b...Magnetic roller 7C・Developing bias power supply 8...Corona charger for pre-charging 9...Corona charger for transfer Applicant Mi7...Tacamera Co., Ltd., j.

Claims (1)

[Scope of Claims] 1. A first step of forming a first latent image on the surface of an electrostatic latent image carrier;
A second latent image forming a second latent image of the same polarity but different potential.
process, resistance value 107 Ωcm or more, average particle size 25-9
A ferromagnetic carrier of 0 μm has a resistance value of 1 g12 (6 or more, the first toner has an average particle size of 5 to 20 μm, and the first toner is charged by friction to a constant polarity due to contact with the carrier. The second toner has a resistance value of 1012 Ωα or more and an average particle size of 5 to 20 μm, which is triboelectrically charged to a polarity opposite to that of the friction band, but is not substantially triboelectrified by contact with the carrier. The latent image is developed using a magnetic developer in which at least one of the first and second toners has magnetism, and a second toner is developed for each of the first and second latent images. 1
1. 2nd step. 3rd step for selectively adhering toner to form a toner image.
and a fourth step of transferring the toner image from the surface of an electrostatic latent image carrier to the surface of a transfer material. 2. An electrophotographic photoreceptor is used as an electrostatic latent image carrier, and in the first and second steps, a positive image is exposed to light on the uniformly charged surface of the photoreceptor to form a first latent image, and then a defective image is formed. 2. A composite image copying method according to claim 1, wherein the image is exposed to form a second a image. 3. The composite image copying method according to claim 2, wherein the polarity of the first latent image and the frictional charging polarity of the second toner are opposite in polarity. 4 In the third step, the first and second latent images are developed based on a magnetic brush development method using a developing electrode to which a developing bias is applied that is somewhat higher than the potential of the non-image area on the surface of the photoreceptor. A composite image copying method according to claim 2, characterized in that: 2. The synthetic image copying method according to claim 1, wherein the 5° ferromagnetic carrier is composed of a single ferromagnetic particle.