JPH04158373A - Color electrophotographing method - Google Patents

Abstract

PURPOSE:To obtain a high-quality color picture generating no disturbance or turbidity of an image by mixing toners and magnetic resin carriers with preset average grain sizes, and arranging a developing roller oppositely to a photosensitive body at a preset gap for development. CONSTITUTION:Electrifying, exposing and reflection-developing processes are repeated with multiple toners to form a color toner image on a photosensitive body, then it is transferred onto the paper. Grain sizes of the toner and carrier of the two-component magnetic brush developing powder are changed, and the contact pressure to a photosensitive body drum 50 is measured. The developing gap and the thickness limit gap of the developing powder are made equal in the development condition. A toner with the average grain size about 5mum and a carrier with the average grain size about 30mum are mixed, the developing gap is set to 0.3 mm, then a toner with the average grain size about 1mum and a carrier with the average grain size about 15mum are mixed, and the developing gap is set to 0.2 mm. A sharp, high-quality, full-color picture is obtained.

Description

[Detailed Description of the Invention] Industrial Field of Application The present invention relates to an image forming method that can be used in color hard copy devices such as copying machines and printers. In an electrophotographic apparatus (for example, after an electrostatic latent image is written on an electrostatic latent image carrier such as an electrophotographic photoreceptor, charged toner is electrostatically deposited and developed, and then the polarity of the toner is reversed. A method of corona transfer onto plain paper using a corona charger to which a polar voltage is applied to obtain a toner image on plain paper is well known.One example of such a method is disclosed in Japanese Patent Application No. 1983-
There is No. 196586. The outline will be explained using FIG. 3.

Developing units 1, 2, and 3 (Y) are non-contact non-magnetic 1-component developing units that use a DC electric field to fly toner. , 8, 9 and blades 10, 11, 12 made of urethane rubber.The toner is frictionally charged by the fur brushes 7, 8, 9, and the developing roller 4,
5, 6 and then thinned by blades 111, 12. Even if developer unit 1 contains yellow (Y) toner, developer unit 2 contains magenta (M), and developer unit 3 contains cyan (C) toner, this toner is
Each color is a non-magnetic component insulating toner with a particle size of about 10 μm made of a charge control agent and the like. Each developing device has a photoreceptor 15
The developing roller 4 is installed oppositely around the developing roller 4 during development.
, 5, 6 and the photoreceptor 15 are close (0.15 mm) L
Toner contacts the photoconductor and separates (0, 7) when not being developed.
A detachment mechanism is attached to the unit. Further, the black developing device 13i1 is a contact type developing device containing a two-component developer consisting of an insulating toner and a magnetic carrier, which is widely used in electrophotographic apparatuses. This black developing device 13k is installed around the photoreceptor 15 facing each other with a constant gap between the developing roller 14 and the photoreceptor 15, and is close to the photoreceptor 15 during development (0.5 mm).L is a separation mechanism that moves away when not developing. Even if the drum is installed, an amorphous selenium telluride (Se-Te) photoconductor drum 15 is used as the photoconductor.
After charging to 0V, the semiconductor laser 17 is caused to emit light.
A negative black signal is exposed on the photoreceptor 15 to form an electrostatic latent image. After the latent image is reversely developed in the black developing device 13 in a developing state in which +600V is applied to the developing roller 14 to form a black toner image, the -high-density light body 15 is transferred to the AC corona charger 18.
Then, use the corona charger 16 again to remove the static electricity from the photoreceptor 15.
The photoreceptor 15 is exposed to signal light corresponding to yellow by the semiconductor laser 17 to form a yellow electrostatic latent image.

Next, this photoreceptor is passed through a yellow developer 1 in a developing state with +600V applied to the developing roller 4, a magenta developer 2, a cyan developer 3, and a black developer 13 in a non-developing state to form a yellow toner image. Formation Step 4 Next, the photoreceptor 15 is charged with an AC corona charger 18, and then the photoreceptor 15 is charged to +810V with the corona charger 16 again. That night, a signal light corresponding to magenta is exposed by the semiconductor laser 17 to form a magenta electrostatic latent image.

Missing number: yellow developer l with photoreceptor 15 in non-developing state;
A magenta toner image is formed by passing the developing roller 5 through the magenta developing device 2 in a developing state where +800V is applied.After that, the photoreceptor 15 is passed through the cyan developing device 3 and the black developing device 13 in a non-developing state. Next, the photoreceptor 15 is neutralized by the AC corona charger 18, and the photoreceptor 15 is charged again to +850V by the corona charger 16. After that, the semiconductor laser 17 is used to expose the signal light corresponding to cyan to form a cyan electrostatic latent image. Next, the photoreceptor 15 is passed through the yellow developer 1 and magenta developer 2 in a non-developing state, and the cyan developer 3 in a developing state with +830V applied to the developing roller 6 to form a cyan toner image. To complete a color image on the photoreceptor 15, the plain paper 19 is conveyed on the transfer belt 21 while being in contact with a stainless steel fur brush 20 to which a voltage of +1 kV is applied, and the paper adsorption charger 22
The color toner image obtained on the light body 15 is transferred by the transfer charger 23, and the paper is charged by the paper separation charger 24. , the paper is separated from the transfer bell (21), passed between a pair of chargers consisting of a positive charger 25 and a negative charger 26, charged, and then thermally fixed by a fixing device 27.

Problems to be Solved by the Invention Instead of the non-contact DC electric field flying development method used in the conventional example, contact development was performed using a two-component magnetic brush developer, which is a longer-life developer. As a two-component developer, a toner with a particle size of about 10 μm and a toner with a particle size of about 100 μm are used.
Developed using a mixture of µm iron powder carrier and the development gap set to 500 µm.Results
It was found that significant image disturbance and color turbidity occurred, making it unsuitable for reproducing full-color images.The purpose of the present invention is to provide a color electrophotographic method in which a toner image is superimposed on a CTG light body, which carries a toner image. It is an object of the present invention to provide a high-quality color electrophotographic developing method that does not cause image disturbance or color turbidity by further performing contact development on the photoreceptor. A color electrophotographic method in which a color toner image is formed on a photoreceptor and then transferred all at once to paper using L. A toner and a magnetic resin carrier having an average particle diameter of 30 μm or less are mixed, and the mixture is supported on a developing roller containing a magnetic roller, and the developing roller is placed opposite to the photoreceptor with a development gap of 0.3 mm or less, and the developer is In the color electrophotographic method, which is a developing process in which the toner and carrier are developed by contacting them with the photoreceptor, the particle sizes of the toner and carrier of the two-component magnetic brush developer are changed, and the contact pressure to each photoreceptor and the developing state are adjusted. The round resistance development gap and the developer layer thickness regulation gap were always equal. As a result, the average particle size was approximately 10 μm.
toner and carrier of about 100 μm are mixed, and the development gap is set to 0°5 mm, the contact pressure is 10
~80g/cm'' At this time, significant disturbance and color turbidity occur in the image, making it unsuitable for reproducing full-color images.
Mix with carrier of about 30 μm and set the development gap to 0.
When the contact pressure was set to 3 mm, the contact pressure was 3 to 8 g/cm. Because the contact pressure of the magnetic brush against the toner image can be made smaller than before, the magnetic brush does not rub against the toner image, causing disturbances in the side image and color turbidity.Thus, high-resolution contact development is possible. It is possible to perform color electrophotographic recording using a 2-component developer, which can provide high-quality color images. It is also possible to use a two-component developer, which has less deterioration and a longer life than conventional non-magnetic component developers. Improved device reliability
In other words, the present invention (because the particle size of Yotoner is small, it is particularly suitable for full-color reproduction in which new colors are synthesized by overlapping toners). Not only that, even if multiple layers of toner are stacked, the ink layer does not become thick, resulting in a completely natural color image, just like gravure printing.

EXAMPLES Below, examples of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of an apparatus using the color electrophotographic method of the present invention.

Amorphous selenium (
Se-Te) photosensitive layer (thickness: 63 μm, dielectric constant: 7, functionally separated selenium photoreceptor sensitized to long wavelengths in the infrared region, half-decreased exposure at wavelength 790 nm: 0.6 μJ/
c m”) at a circumferential speed of 1 in the direction of arrow A.
A tungsten charger (51) rotates at 60 mm/s inside a shield case made of aluminum (AI) with one side open.
A so-called scorotron charger is used, in which a wire consisting of a material such as W) is stretched and a mesh-like grid electrode is arranged between the wire and the photoreceptor drum 50. The light intensity of the semiconductor laser on the surface of the photoreceptor drum 50 is 1.5 mW, even if it is used as a scanning optical system consisting of a polygon mirror, an f-theta lens, etc.
As the exposure device 52, a light emitting diode array (LED) and a self-focusing rod lens array (SLA) are used.
), or (Y) You can also use a light source such as a phosphor and a liquid crystal shutter array (LC5). ) is a contact type magnetic brush developer containing a two-component developer consisting of an insulating toner and a magnetic carrier.

(Hereinafter, subscripts a - d are respectively a: yellow, b
: Magenta, C: Cyan, d: Indicates that it is part of the black developing device configuration. ) Developing device 53a
-dζ Each developing device 53a-dl is installed opposite to the periphery of the photosensitive drum 50 with a constant gap (development gap) between each of the developing rollers 54a to 54d and the photosensitive drum 50;
L As shown in the direction of arrow B, a separation mechanism (not shown) is attached that approaches the photosensitive drum 50 during development and separates from it during non-development. Developing device 53 (back side developing roller 54, doctor blade 55, scraper 56,
It is composed of a developer supplying member 57, a developer stirring blade 58, and a developing roller 54 (as shown in FIG. 2), and a developing sleeve 60 containing a magnetic roller 59 with eight magnetic poles (hereinafter referred to as a mag roller). The magnetic flux density on the developing sleeve 60 is 1000 Gs.The developing sleeve 60 has a diameter of 31 m and a rotation speed of 130 rpm, and the rotation speed of the mag roller 59 is 1300 rpm.

At this time, it is assumed that the developing sleeve 60 and the mag roller 59 rotate in the directions of arrows C and D shown in the figure, respectively, and transport the developer in the direction of arrow E. The developing device 5 is supplied from the outside by a toner supply coil member (not shown).
The developer is fed into the developer stirring blade 58, mixed with carrier, and triboelectrically charged.

Furthermore, the developer supplied and carried on the developing roller 54 is supplied to the developing roller 54 by the developer supplying member 57 (
The magnetic doctor blade 55 regulates the gap to 0.
．． Even though the developer on the developing roller 54 is structured to be scraped off by the scraper 56 after being used for development, the toner on the developing roller 54 is statically attached to the photoreceptor drum 50 during development. The toner used in the present invention is produced by dispersing a coloring pigment such as carbon black or phthalocyanine in a binder resin such as styrene resin or acrylic resin, and then pulverizing and classifying the toner used in the present invention. The toner particles may be a powder obtained by spray drying, or may be a powder obtained chemically by pearl polymerization, etc.Furthermore, the toner particles may be mixed with the carrier as they are, or depending on the usage conditions (Yotner). It is also possible to use a toner with fine silica particles or fine fluororesin powder attached to its surface (°C). A mixture of 30 to 80% of fine powder such as styrene resin, epoxy resin, styrene acrylic resin, etc. is dispersed and then crushed and classified. yo transfer belt 65, fur brush 66,
It is composed of a paper adsorption charger 67 and a transfer roller 68. Transfer belt 65 (Dai) An endless insulating elastic sheet made of silicone resin, etc. The back surface is conductive treated and rotates in the direction of arrow F. Stainless steel fur brush 661 Transfer the tip to the transfer belt 65
The paper adsorption charger 67 is a so-called corona charger, which applies an electric charge to the back surface of the transfer belt 65 and transfers the recording medium 72 (PPC paper) onto the transfer belt 6.
The transfer roller 68 (a conductive elastic roller) is electrostatically attracted to the surface of the photoreceptor drum 5 through the transfer belt 65 during transfer.
Even if a separation mechanism (not shown) is provided so that the transfer device contacts the 0 with a predetermined pressure and separates when not transferred, the transfer device
Even if a bias voltage with a polarity opposite to the charging polarity of the yotoner is applied to the transfer roller 68, and even if a static eliminator 70 and a cleaner 71 are arranged around the photosensitive drum 50, the static eliminator 70 EL
This is a so-called AC corona charger. Also cleaner 71ζ
It is composed of a roller with a web sheet wound around it, and has a contact/separation mechanism (not shown) that contacts the photoreceptor drum 50 with a predetermined pressure in the direction indicated by arrow H during cleaning, and separates it during non-cleaning. It is provided.

Next, the operation of the embodiment configured as above will be explained in detail.

First, the photoreceptor drum 50 is charged by the charger 51 (corona voltage:
+7 kV, grid voltage 2 kV) to a surface potential of +900 V. Next, the semiconductor laser of the exposure device 52 is caused to emit light, and a negative black signal is exposed on the photoreceptor drum 50 to form an electrostatic latent image. Also, this electrostatic latent image,
After a black toner image is formed by reversal development with a black developing device 53d in a developing state in which +600V is applied to the developing roller 54d, the photosensitive drum 50 is charged to an AC corona charger 70 (applied AC voltage: 4.5 kVrms, DC bias). Next, charger 51 (corona voltage: +7 kV, grid voltage: +600 V) charges photoreceptor drum 50 at +60 V.
It is charged to 0V, and the exposure device 5 is placed on the photo drum 50.
2, a signal light corresponding to yellow is exposed to form a yellow electrostatic latent image. Next, this photoreceptor drum 50 is
A yellow toner image is formed by contact development by passing through a yellow developing device 53a in a developed state with +600 cm applied to the developing roller 54a, a magenta developing device 53b in a non-developing state, a cyan developing device 53c, and a black developing device 53d. 4 Next Remove the static electricity from this photoreceptor drum 50 using the AC corona charger 70 (applied AC voltage: 4.5 kVrms, DC bias component: +200V). Corona charger 5 again.
1 (corona voltage: +7 kV, grid voltage: +9
40V), the photoreceptor drum 50 is charged to +810V, and then the exposure device 52 exposes the signal light corresponding to magenta to form a magenta electrostatic latent image. Yellow developer 53a1
A magenta toner image is formed by contact development by passing the developing roller 54b through a magenta developing device 53b in a developing state where +800V is applied. Next, the photoreceptor drum 50 is passed through an AC corona charger 70.
(applied AC voltage: 4.5 kVrms, DC bias component, +200V), and then the photoreceptor drum 50 is charged again by the corona charger 51.
The resistor is charged to +850V, and the exposure device 52 exposes the signal light corresponding to cyan to form a cyan electrostatic latent image.Next, the photoreceptor drum 50 is transferred to the undeveloped yellow developing device 53a and the magenta developing device 53a. The toner is passed through the cyan developing device 53c in a developing state in which +830V is applied to the developing roller 54c and the developing roller 54c to form a cyan toner image by contact development. After completing a color image consisting of four color toners, the recording medium 72 is brought into contact with a fur brush 66 to which a voltage of +1 kV is applied, and then sent onto a collection transfer belt 65, and then transferred to a paper adsorption charger 67 (applied voltage: -). A bias voltage (-600V) is applied to the transfer roller 68, and the mold is passed between the photoreceptor drum 50 and the recording medium 7 via the transfer belt 65.
2 and electrostatically transfer the toner image onto the recording medium 72. Finally, the surface of the two photosensitive drums 50 is charged with an AC corona charger 70.
(Applied AC voltage: 4.5 kVrms, DC bias component, +200 V) is used to expose the photoreceptor drum 50 to corona and uniformly remove static electricity.The toner remaining on the photoreceptor is completely removed using the cleaner 71. In this way, The cleaned photoreceptor drum 501 is used for the next color image formation.A color image is actually recorded using the color electrophotographic method and apparatus described above.At this time, a two-component magnetic brush developer is used. The particle size of the toner and carrier was changed, and the contact pressure on the photoreceptor drum 5o was measured, and the development status of each was evaluated. Under each development condition, the development gap and the developer layer thickness regulation gap were equal. Average particle size is approximately 5μm
toner (density 1°3) and carrier (density 2.7) of about 30 μm are mixed and the development gap is set to 0.3 mm, the contact pressure is 3 to 8 g/cm”.
At this time, there was almost no image disturbance due to the rubbing of the magnetic brush or color turbidity due to toner adhesion, and a high-quality full-color image was reproduced.Also, toner with an average particle size of approximately 1 μm and carrier with an average particle size of approximately 15 μm were used. t, % The contact pressure is 1 to 5 when the development gap is set to 0.2 mm.
g/cm", and a sharper, higher-quality full-color image was obtained. This process was repeated 10,000 times at a temperature of 30% and relative humidity of 80%.
The image does not become cloudy, and toner of other colors does not get mixed into the developing machine.
The transfer performance deteriorated significantly.L Cleaning failure occurred.Also, when the average particle diameter of the carrier was set to 5 μm or less, carrier adhesion to the photoreceptor occurred, making it impossible to put it to practical use.The photoreceptor drum used in the present invention 50 is made of amorphous selenium tellurium.Cadmium oxide, subsulfide, organic photoreceptor, etc. can also be used.In particular, if the thickness of the dielectric layer or photosensitive layer is 10 μm or less, the particle size of the toner becomes finer. Furthermore, it is also possible to form a toner image directly on electrostatic recording paper without performing electrostatic transfer. The contact pressure of the magnetic brush against the body surface can be made smaller than before.By sliding the magnetic brush over the toner image, high-resolution color electrophotographic recording can be performed without causing image disturbance or color turbidity.
In addition, compared to conventional non-magnetic component developers, the deterioration of the developer is reduced and its lifespan is extended. It is particularly suitable for full-color reproduction in which new colors are synthesized. It is not thick and is no different from gravure printing.

[Brief Description of the Drawings] Fig. 1 is a configuration diagram of an apparatus using a color electrophotographic method according to the present invention. Fig. 2 is a cross-sectional diagram of a developing roller which is an embodiment of the present invention. Fig. 3 is a conventional color electrophotographic method. 450...Photoreceptor 51...Charged u 52...Exposed images 53a-d...Developer (yellow, magenta, cyan, black), 54...
Developing roller, 59...Mag roller, 60...Developing sleeve, 64...Transfer device Name of agent Patent attorney Akira Okaji and 2 others 511+-*Round drum 5I---弗 den Mupi-transfer 'f 6 Column 1 Diagram Father - Glancing Light Scale Drum, W-Ichisei II D-Ra55-1 Dori Tau Shi -
Doro 0 --- 1 ship 11 three - 2nd cause

Claims (2)

[Claims] (1) A color electrophotographic method in which charging, exposure, and reversal development steps are repeated using toners of multiple colors to form a color toner image on a photoreceptor and then transferred all at once to paper, in which the power of the development process is , a toner having an average particle size of 5 μm or less and a magnetic resin carrier having an average particle size of 30 μm or less are mixed, and the mixture is supported on a developing roller including a magnetic roller, and the developing roller is held at a developing gap of 0.3 mm or less. A color electrophotographic method, which is a developing step in which the developer is placed opposite to a photoreceptor and brought into contact with the photoreceptor for development. (2) The color electrophotographic method according to claim 1, wherein the toner colors are yellow, magenta, cyan, and black.