JP2002258618A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device whose developing performance and transfer performance in the case of forming an image are made excellent. SOLUTION: This image forming device is provided with a layer thickness regulating means for regulating the layer thickness of a magnetic brush on a developing means. By constituting two-component developer of magnetic carrier and flat toner, forming the magnetic brush of the two-component developer consisting of the magnetic carrier and the flat toner, and sticking the flat surface of the flat toner to a latent image on an image forming body, a toner image is formed in the image forming device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus having a developing means used for image formation such as a copying machine, a printer, a facsimile, etc.
The present invention relates to an image forming apparatus that improves developability and transferability.

[0002]

2. Description of the Related Art As an image forming apparatus for forming an image using a spherical or irregular toner formed by a usual pulverizing method or polymerization method, a toner image is formed on an image forming body using a spherical or irregular toner. After the image is formed, the toner image is transferred onto the transfer material and fixed, or the toner image is superimposed on the image forming body using spherical or irregular toner, and the superimposed color toner image is formed. After forming on the image forming body, the color toner image on the image forming body is collectively transferred onto the transfer material and fixed. The toner image formed on the image forming body is sequentially transferred to the intermediate transfer body using the changed toner, and a superimposed color toner image is formed on the intermediate transfer body. Batch to transfer material Transferred, the image forming apparatus or the like is used for fixing.

[0003]

The image formed by each image forming apparatus using the spherical or irregular toner described above consumes a large amount of toner and therefore has irregularities on the surface, and has poor developability and poor print-like image quality. It was difficult to get. Further, since the toner consumption is large, the toner layer becomes thick, the transfer rate is low, and the transferability is poor. Therefore, a high-density image cannot be obtained. In addition, toner scattering and uneven development occurred, and the developability was poor, and a good image could not be obtained. In particular, this problem is remarkable in the case of a superposed color toner image, and the transferability and the developability are poor.

Until now, in order to obtain a print-like image, attempts have been made to reduce the toner consumption by reducing the particle size of the toner, eliminate irregularities on the surface, and obtain uniform gloss. As the particle size of the toner decreases, the covering power of the toner decreases, and sufficient image density cannot be obtained.
In addition, image forming processes such as development, transfer, and cleaning of the image forming body are difficult, and the image quality of a print-like image cannot be obtained by an electrophotographic image forming method.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus which solves the above-mentioned problems and has good developability and transferability in image formation.

[0006]

An object of the present invention is to provide an image forming apparatus comprising: an image forming body; and a developing means for developing a latent image on the image forming body using a magnetic brush made of a two-component developer. A developing means is provided with a layer thickness regulating means for regulating a layer thickness of the magnetic brush, and the two-component developer is constituted by a magnetic carrier and a flat toner, and a two-component developer comprising the magnetic carrier and a flat toner is used. An image forming apparatus (first invention) is characterized in that the magnetic brush is formed, and a flat image of the flat toner is attached to a latent image on the image forming body to form a toner image.

[0007] It is another object of the present invention to sequentially transfer toner images formed by a plurality of toner image forming means onto an intermediate transfer member to form a superimposed color toner image on the intermediate transfer member. After the color toner image on the transfer body is collectively transferred onto the transfer material, the fixing device fixes the color toner image on the transfer material in an image forming apparatus, wherein the toner is flat toner, and the flat toner is An image forming apparatus (second invention) is characterized in that a flat surface is attached to the image forming body, and a superposed color toner image is formed on the intermediate transfer body while maintaining the flat surface. You.

Another object of the present invention is to sequentially transfer toner images formed by a plurality of toner image forming means onto an intermediate transfer member by developing with a developer containing toner, and to superimpose the toner images on the intermediate transfer member. An image forming apparatus that forms a combined color toner image, and collectively transfers the color toner image on the intermediate transfer body onto a transfer material, and then fixes the color toner image on the transfer material with a fixing device. Image forming, wherein the toner is flat toner, a flat surface of the flat toner is adhered to the intermediate transfer body, and a superposed color toner image is formed on the transfer material while maintaining the flat surface. This is achieved by a device (third invention).

Further, the above object is to provide an image forming apparatus for forming a toner image on an image forming body using a developer containing a toner and forming a superposed color toner image, wherein the toner is a flat toner, After attaching the flat surface of the flat toner to the image forming body, the color toner image is transferred while maintaining the flat surface, and 50% or more of the color image data for forming the color toner image is transferred. This is achieved by an image forming apparatus (fourth invention) which performs undercolor removal.

[0010] Another object of the present invention is to provide an image forming apparatus for forming a toner image on an image forming body using a developer containing a toner, wherein the toner is a flat toner and image data for forming the toner image is used. A latent image is formed on the image forming body by image exposure by performing the area modulation of the image forming apparatus, and the flat surface of the flat toner is adhered to the image forming body. Is done.

[0011]

Embodiments of the present invention will be described below. Note that the description in this column does not limit the technical scope of the claims and the meaning of terms. Also, the following assertive description in the embodiment of the present invention indicates the best mode, and does not limit the meaning of the terms of the present invention or the technical scope. In the following description of each image forming apparatus in the embodiment, members having the same functions and structures are given the same numbers or the same symbols.

First, examples of an image forming apparatus using flat toner or flat toner and a magnetic carrier (spherical carrier or flat carrier) as a developer will be described with reference to FIGS. FIG. 1 is a cross-sectional configuration diagram of a color image forming apparatus showing a first example of an embodiment of an image forming apparatus using flat toner or flat toner and a magnetic carrier according to the present invention, and FIG. FIG. 3 is a cross-sectional configuration view of a color image forming apparatus showing a second example of an embodiment of an image forming apparatus using the flat toner or the flat toner and the magnetic carrier according to the present invention, and FIG. FIG. 9 is a sectional configuration diagram of a color image forming apparatus showing a third example of an embodiment of an image forming apparatus using a magnetic carrier.

According to FIG. 1, a photosensitive drum 10a as an image forming body is provided on the outer periphery of a cylindrical base formed of a light-transmitting member such as glass or light-transmitting acrylic resin.
A transparent conductive layer and a photoconductor layer of an organic photosensitive layer (OPC) are formed.

The photosensitive drum 10a is rotated clockwise as indicated by an arrow in FIG. 1 with the light-transmitting conductive layer grounded by power from a drive source (not shown).

In the present invention, the exposure beam for image exposure is:
The photoconductor layer of the photoconductor drum 10a, which is the image forming point, only needs to have an exposure light amount of a wavelength that can provide an appropriate contrast with respect to the light attenuation characteristic (photocarrier generation) of the photoconductor layer. . Therefore, the light transmittance of the light-transmitting substrate of the photosensitive drum in the present embodiment does not need to be 100%, and may have a characteristic of absorbing a certain amount of light when transmitting the exposure beam. . The point is that any suitable contrast can be provided. As a material of the light-transmitting substrate, an acrylic resin, particularly one obtained by polymerizing a methyl methacrylate monomer, is preferably used because of its excellent light-transmitting properties, strength, accuracy, surface properties, etc. Various translucent resins such as acryl, fluorine, polyester, polycarbonate, polyethylene terephthalate and the like used for the above can be used. Further, as long as it has a light-transmitting property with respect to the exposure light, it may be colored. As the light-transmitting conductive layer, indium tin oxide (I
TO), tin oxide, lead oxide, indium oxide, copper iodide, or a metal thin film of Au, Ag, Ni, Al, or the like that maintains light transmissivity. Reactive deposition method, various sputtering methods, various CV
D method, dip coating method, spray coating method and the like can be used.
Various organic photosensitive layers (OPC) can be used as the photoconductor layer.

The organic photosensitive layer serving as the photosensitive layer of the photoconductor layer includes a charge generation layer (CGL) mainly composed of a charge generation substance (CGM) and a charge transport layer (CTM) mainly composed of a charge transport substance (CTM). And CTL). An organic photosensitive layer having a two-layer structure has high durability as an organic photosensitive layer due to its thick CTL and is suitable for the present invention.
The organic photosensitive layer may have a single layer structure containing a charge generation material (CGM) and a charge transport material (CTM) in one layer. ,
Usually, a binder resin is contained.

A scorotron charger 11 as a charging unit described below, and an exposure optical system 12 as an image writing unit
a, The developing device 13 as a developing unit is prepared for an image forming process for each color of yellow (Y), magenta (M), cyan (C), and black (K), respectively. Are arranged in the order of Y, M, C, and K with respect to the rotation direction of the photosensitive drum 10a indicated by the arrow in FIG.

The scorotron charger 11 is mounted so as to face and be close to the photosensitive drum 10a in a direction (perpendicular to the plane of FIG. 1) orthogonal to the moving direction of the photosensitive drum 10a as an image forming body. The above-mentioned organic photoreceptor layer of the drum 10a is charged by a control grid (no sign) maintained at a predetermined potential and a corona discharge electrode having, for example, a discharge wire (no sign) as a corona discharge electrode and having the same polarity as the toner. The operation (in this embodiment, negative charging) is performed, and a uniform potential is applied to the photosensitive drum 10a. As the corona discharge electrode, a sawtooth electrode or a needle electrode may be used.

The exposure optical system 12a is a linear exposure element (not shown) in which a plurality of LEDs (light emitting diodes) as light emitting elements of image exposure light are arranged in an array in parallel with the axis of the photosensitive drum 10a. And a SELFOC lens (not shown) as an equal-magnification imaging element are configured as an exposure unit attached to a holder. An exposure optical system 12a for each color is provided on a cylindrical holder 20 as an exposure optical system holding member.
Is attached and housed inside the base of the photosensitive drum 10a. Other exposure elements include FL (phosphor emission),
A linear element in which a plurality of light emitting elements such as EL (electroluminescence) and PL (plasma discharge) are arranged in an array is used.

The exposure optical system 12a includes a photosensitive drum 10a.
The above exposure position is determined by the scorotron charger 11 and the developing device 1
In the state provided between the developing device 13 and the developing device 13 in the rotation direction upstream of the photosensitive drum 10a, the photosensitive drum 10a is disposed inside the photosensitive drum 10a.

The exposure optical system 12a performs image processing based on image data of each color sent from a separate computer (not shown) and stored in a memory, and then forms an image on a uniformly charged photosensitive drum 10a. After exposure, the photosensitive drum 10a
A latent image is formed thereon. The emission wavelength of the light-emitting element used in this embodiment is preferably in the range of 680 to 900 nm, which is generally high in the transmittance of the Y, M, and C toners. A shorter wavelength that does not sufficiently transmit light to the toner may be used.

The developing unit 13 will be described in detail later. Two components (one component may be used) of yellow (Y), magenta (M), cyan (C) or black (K) are provided inside the developing unit 13. A developer (a flat toner or a developer having a flat toner and a magnetic carrier, which will be described in detail later) is accommodated, and each has a thickness of, for example, 0.5 to 1 mm.
It has a developing sleeve 131 which is a developer conveying member formed of a cylindrical non-magnetic stainless steel or aluminum material having an outer diameter of 15 to 25 mm.

In the developing area, the developing sleeve 131 is kept out of contact with the photosensitive drum 10a by a contact roller (not shown) with a predetermined gap, for example, 100 to 1000 μm, to keep the developing sleeve 131 in the rotating direction of the photosensitive drum 10a. It rotates in the forward direction at the closest position, and at the time of development, an AC voltage AC is superimposed on a DC voltage of the same polarity as the toner (in this embodiment, a negative polarity) or a DC voltage with respect to the developing sleeve 131. By applying the developing bias voltage, non-contact reversal development is performed on the exposed portion of the photosensitive drum 10a.

As described above, the developing device 13 includes the photosensitive drum 10a formed by charging by the scorotron charger 11 and image exposure (image writing) by the exposure optical system 12a.
The upper electrostatic latent image is reversely developed in a non-contact state with toner having the same polarity as the charged polarity of the photoconductor drum 10a (in the present embodiment, the photoconductor drum is negatively charged and the toner has a negative polarity).

The photosensitive drum 10a is rotated clockwise as indicated by an arrow in FIG. 1 by starting an image forming body driving motor (not shown) at the start of image formation, and at the same time, the photosensitive drum 10 is charged by the charging action of the Y scorotron charger 11. Application of a potential to 10a is started. After a potential is applied to the photosensitive drum 10a, exposure (image writing) by a first color signal, that is, an electric signal corresponding to Y image data is started in the Y exposure optical system 12a, and the rotation of the photosensitive drum 10a is started. By scanning, an electrostatic latent image corresponding to the yellow (Y) image of the original image is formed on the photosensitive layer on the surface. This latent image is reversely developed by the Y developing device 13 in a non-contact state, and a toner image composed of yellow (Y) flat toner is formed on the photosensitive drum 10a.

Next, the photoconductor drum 10a is placed on the yellow (Y) toner image by the M scorotron charger 1
A potential is applied by the charging action of M, and the exposure optical system M of M
Exposure (image writing) is performed by an electric signal corresponding to the second color signal 2a, that is, the image data of magenta (M), and the yellow (Y) of the yellow (Y) is developed by non-contact reversal development by the M developing unit 13 A toner image made of magenta (M) flat toner is superimposed on a toner image made of flat toner.

According to the same process, the C scorotron charger 11, the exposure optical system 12a and the developing device 13 further form a toner image composed of cyan (C) flat toner corresponding to the third color signal. By the scorotron charger 11, the exposure optical system 12a, and the developing device 13, a toner image composed of black (K) flat toner corresponding to the fourth color signal is sequentially superimposed and formed, and the photosensitive drum 10a is formed.
Within one rotation, a superimposed color toner image composed of flat toner is formed on the peripheral surface.

As described above, in this embodiment, Y, M,
Photoconductor drum 10a by C and K exposure optical system 12a
The exposure of the organic photosensitive layer is performed through a transparent substrate from the inside of the photosensitive drum 10a. Therefore, the second,
Exposure of an image corresponding to the third and fourth color signals can form an electrostatic latent image without being shielded by the previously formed toner image, which is preferable. Exposure may be performed from outside.

On the other hand, recording paper P, which is mainly used as a transfer material (recording material), is sent out from a paper feed cassette 15 as a transfer material storage means by a feed roller (no code), and is fed by a feed roller (no code). The sheet is fed and conveyed to a timing roller 16 as a transfer material feeding unit.

The recording paper P is synchronized with the superimposed color toner image composed of flat toner carried on the photosensitive drum 10a by the driving of the timing roller 16, and a paper charger as a transfer material charging means is provided. Due to the charging of 150, it is attracted to the conveyor belt 14A and is fed to the transfer area (no symbol). The recording paper P closely transported by the transport belt 14A is transferred around the photosensitive drum 10a by a transfer unit 14C as a transfer unit to which a voltage having a polarity opposite to that of the toner (positive polarity in the present embodiment) is applied in a transfer area. The superimposed color toner images made of flat toner on the surface are collectively transferred onto the recording paper P.

The recording paper P on which the superimposed color toner image made of flat toner has been transferred is neutralized by a paper separation AC neutralizer 14h as transfer material separating means, separated from the transport belt 14A, and transferred to the fixing device 17. Is conveyed.

The fixing device 17 includes a fixing roller 17a as a fixing roller member (a roller member provided on the surface of the transfer material having the toner image) for fixing the superposed color toner image made of flat toner, and a fixing device. Roller 17a
And a pressure roller member 17b as a pressure roller member (a roller member provided on the surface of the transfer material not having the toner image).
Halogen lamp HLa, which is a heating means having a heating filament (no symbol) as a heat source,
Is provided.

The recording paper P is sandwiched by a nip portion N formed between the fixing roller 17a and the pressure roller 17b, and a superposed color of flat toner on the recording paper P is applied by applying heat and pressure. The toner image is fixed and the recording paper P
Is sent by a paper discharge roller 18 and discharged to a tray at the top of the apparatus.

The toner remaining on the peripheral surface of the photoconductor drum 10a after the transfer is cleaned by a photoconductor cleaning blade (not numbered) provided in a photoconductor cleaning device 19 as an image forming body cleaning means. The photosensitive drum 10a from which the residual toner has been removed is uniformly charged by the scorotron charger 11, and enters the next image forming cycle.

In the above-described image forming apparatus, color image formation has been described, but image formation of only a monochrome image can be performed.

According to FIG. 2, as shown in the sectional configuration diagram,
At the top of the image forming apparatus, there is a document table made of a transparent glass plate or the like, and a document placing section 111 made up of a document cover or the like that covers the document D placed on the document table. , A first mirror unit 112 in the apparatus body,
Second mirror unit 113, main lens 120, color C
An image reading unit A including a CD 123 or the like is provided. The first mirror unit 112 includes an exposure lamp 114 and a first mirror 115, and is attached in parallel with the document table so as to be linearly movable in the horizontal direction of the drawing, and optically scans the entire surface of the document D. The second mirror unit 113 integrally includes the second mirror 116 and the third mirror 117, and the first mirror unit 112 always maintains a predetermined optical path length.
It moves linearly in the same direction on both sides at half the speed of. Of course, the movement of the second mirror unit 113 is parallel to the platen similarly to the first mirror unit 112. The image of the document D on the document table illuminated by the exposure lamp 114 is transmitted to the first mirror 115 and the second mirror 11 by the main lens 120.
6. An image is formed on the color CCD 123 via the third mirror 117. When the scanning is completed, the first mirror unit 112 and the second mirror unit 113 return to their original positions, and wait for the next copy.

Image data of each color obtained by the color CCD 123 is subjected to image processing in an image processing section, and laser writing is performed as an image signal in an image forming section E described below.

The image forming apparatus shown in FIG. 2 is a tandem-type color image forming apparatus using an intermediate transfer member as an image forming portion E, and a black (K) is formed on the peripheral edge of a transfer belt 14a as an intermediate transfer member. , Cyan (C), magenta (M)
Sets of four process units 1 composed of yellow and yellow (Y)
00 are provided in this order from the upstream side in the rotation direction of the transfer belt 14a.
K, C, M using the flat toner described in detail later
And the Y toner image are formed, the toner image composed of the flat toner is superimposed and transferred on the transfer belt 14a, and the transferred superimposed color toner image is collectively transferred onto a recording paper P as a transfer material. Then, the toner is fixed and discharged outside the apparatus.

Since the four process units 100 all have a common structure, only one of them will be described.

The photosensitive drum 10 serving as an image forming body has a conductive layer and an organic photosensitive layer (OPC) on the outer periphery of a cylindrical substrate.
Is formed.

The photosensitive drum 10 is rotated counterclockwise as indicated by an arrow with the conductive layer grounded by power from a drive source (not shown) or by the transfer belt 14a.

Numeral 11 denotes a scorotron charger as charging means, which is attached to the photosensitive drum 10 in a direction perpendicular to the moving direction of the photosensitive drum 10 so as to face and be close to the photosensitive drum 10.
The photosensitive drum 1 is driven by corona discharge having the same polarity as the toner.
A uniform potential is given to 0.

Reference numeral 12 denotes an exposure optical system as an image writing means for performing K, C, M, and Y image exposure based on image data.
Is a scanning optical system that performs scanning in parallel with the rotation axis. A latent image is formed by performing image exposure on the uniformly charged photoconductor drum 10 by the exposure optical system 12.

As will be described in detail later, a developing unit 13 containing a two-component developer composed of negatively charged flat toner and a magnetic carrier (spherical carrier or flat carrier) is provided at the periphery of the photosensitive drum 10 as will be described in detail later. A reversal development is carried out by a developing sleeve 131 as a developer conveying member which has a built-in magnetic field generating means having a fixed magnetic pole and rotates while holding the developer.

The developer is a mixture of a magnetic carrier (spherical carrier or flat carrier) and flat toner, which will be described in detail later.
It is conveyed to the development area with the layer thickness being regulated to 0.6 mm.

A developing bias in which an AC voltage is superimposed on a DC voltage is applied between the developing sleeve 131 and the photosensitive drum 10. Since the charge of the toner is the same polarity (negative) as the DC voltage, the flat toner which has been triggered by the AC voltage to separate from the magnetic carrier adheres to the _VH portion having the absolute value of the potential higher than the DC voltage. Instead, the toner amount corresponding to the potential difference adheres to the portion of _VL where the absolute value of the potential is low, and the image is visualized (a toner image composed of flat toner is formed by reversal development). Further, only a DC voltage may be applied between the developing sleeve 131 and the photosensitive drum 10. The development may be contact development. The toner image composed of the flat toner is transferred onto a transfer belt 14a described later at a transfer position. The transfer residual toner remaining on the photoconductor drum 10 after the transfer is cleaned by a photoconductor cleaning device 19 that electrostatically collects the toner.

The transfer belt 14a, in which four color process units 100 of K, C, M and Y face in parallel, has a volume resistivity of 10 ¹⁰ Ω · cm to 10 ¹⁵ Ω · cm and a surface resistivity of 10 ¹⁰
~10 ¹⁵ Ω / □ is an endless belt, for example modified polyimide, thermal curing polyimide, ethylene tetrafluoroethylene copolymer, polyvinylidene fluoride, and dispersed with a conductive material engineering plastics nylon alloy, such as, 0.1 thickness It is a seamless belt having a two-layer structure in which a fluorine coating having a thickness of 5 to 50 μm is preferably formed on the outside of a semiconductive film substrate having a thickness of 1.0 to 1.0 mm, preferably as a toner filming preventing layer. In addition, as the base of the transfer belt 14a, a semiconductive rubber belt having a thickness of 0.5 to 2.0 mm in which a conductive material is dispersed in silicon rubber or urethane rubber can be used. Transfer belt 1
Reference numeral 4a is stretched around a drive roller 14d, a driven roller 14e, a tension roller 14k, and a backup roller 14j. At the time of image formation, the drive roller 14d is rotated by a drive motor (not shown). In the transfer position, the transfer belt 14a is pressed against the photosensitive drum 10 by the primary transfer roller 14c as a first transfer unit, and the transfer belt 14a is rotated in the direction indicated by the arrow in the drawing.

The primary transfer roller 14c composed of a roller member as a first transfer unit for each color is provided on a transfer belt 14a.
Are provided to face the photosensitive drums 10 for each color, and a transfer area (no symbol) for each color is formed between the transfer belt 14a and the photosensitive drum 10 for each color. A DC voltage having a polarity opposite to that of the toner (positive polarity in the present embodiment) is applied to the primary transfer roller 14c for each color, and a transfer electric field is formed in the transfer area. The toner image is transferred onto the transfer belt 14a.

The static eliminator 14m, which is a static eliminator for each color,
Preferably, the transfer belt 14a is constituted by a corona discharger, and charges the transfer belt 14a charged by the primary transfer roller 14c.

The process unit 1 of black (K) is started by starting a photoconductor drive motor (not shown) by starting image recording.
The photoconductor drum 10 is rotated in the direction indicated by the arrow in the figure, and at the same time, the application of a potential to the K photoconductor drum 10 is started by the charging action of the K scorotron charger 11.

After a potential is applied to the K photosensitive drum 10, image writing is started by an electrical signal output from the control unit by the K exposure optical system 12, and the control unit is placed on the surface of the K photosensitive drum 10. An electrostatic latent image corresponding to the output image from is formed.

The K latent image is subjected to reversal development in a contact or non-contact state by a K developing unit 13 and a toner image composed of K flat toner by K flat toner according to the rotation of the K photosensitive drum 10. Is formed.

The toner image composed of the K flat toner formed on the K photoreceptor drum 10 as the image forming body by the above-described image forming process is the primary transfer of K in the K transfer area (no sign). The image is transferred onto the transfer belt 14a by the roller 14c.

Slightly after the operation of the K process unit 100, the photosensitive drum 10 of the cyan (C) process unit 100 is rotated in the direction shown by the arrow in the drawing, and at the same time, the charging action of the C scorotron charger 11 is performed. As a result, the application of the potential to the C photoconductor drum 10 is started.

After the potential is applied to the photosensitive drum 10 of C, image writing by an electric signal corresponding to the image data of C is started by the exposure optical system 12 of C in synchronization with the toner image of K. An electrostatic latent image corresponding to the image C of the original image is formed on the surface of the photosensitive drum 10.

The C latent image is subjected to reversal development in a contact or non-contact state by a C developing unit 13 and a toner image composed of C flat toner by C flat toner according to the rotation of the C photosensitive drum 10. Is formed.

The toner image formed of the C flat toner formed on the photosensitive drum 10 of the image forming body C by the above-described image forming process is primarily transferred to the C transfer area (no symbol). The toner image is transferred onto the toner image formed of the flat K toner on the transfer belt 14a by the roller 14c.

Next, the transfer belt 14a is synchronized with the M toner image, and the magenta (M) process unit 1
The toner image composed of the M flat toner corresponding to the M image data formed on the M photoconductor drum 10 by M.00 in the M transfer area (no symbol) by the M primary transfer roller 14c. Are superposed and formed on the superposed toner images made of the flat toners K and C.

By the same process, synchronization is achieved with the superposed toner image composed of K, C, and M flat toners.
The Y formed on the Y photoconductor drum 10 by the process unit 100 using the yellow (Y) flat toner
The toner image composed of the Y flat toner using the Y flat toner corresponding to the image data is transferred to the Y transfer area (no sign).
In the above, the Y primary transfer roller 14c is formed by being superimposed on the superposed toner images composed of the K, C, and M flat toners, and the K, C, M, and Y are formed on the transfer belt 14a. A superimposed color toner image made of flat toner is formed.

The untransferred toner remaining on the peripheral surface of the photosensitive drum 10 for each color after the transfer is cleaned by a photosensitive body cleaning device 19 as an image forming body cleaning unit for each color.

In synchronization with the formation of the superposed color toner image on the transfer belt 14a, the transfer material (recording material) is mainly transferred from a paper feed cassette 15 as a transfer material storage means via a timing roller 16 as a transfer material feeding means. The recording paper P used as the secondary transfer unit 14 is used as the second transfer unit.
g is transferred to the transfer area (no sign), and a superimposed color toner image composed of flat toner on the transfer belt 14a is formed on the recording paper P by the secondary transfer device 14g to which a DC voltage having a polarity opposite to that of the toner is applied. Are transferred collectively. A superposed color toner image composed of flat toners of K, C, M, and Y exists on the recording paper P.

The recording paper P on which the superposed color toner image made of flat toner has been transferred is neutralized by the neutralizing electrode 16b which is a separating means composed of a sawtooth electrode plate, and is conveyed to the fixing device 17.

The fixing device 17 includes a fixing roller 17a as a fixing roller member (a roller member provided on the surface of the transfer material having the toner image) for fixing the superposed color toner images made of flat toner, and a fixing device. Roller 17a
And a pressure roller member (a roller member provided on the surface of the transfer material on the side not having the toner image) pressure roller 17b. A halogen lamp HLa, which is a heating unit having a heating filament (no symbol) as a heat source, is provided in the center of the inside of the fixing roller 17a.

After heat and pressure are applied between the fixing roller 17a and the pressure roller 17b, a superimposed color toner image composed of flat toner on the recording paper P is fixed, and then sent by the discharge roller 18. It is discharged to the tray at the top of the device.

The untransferred toner remaining on the peripheral surface of the transfer belt 14a after the transfer is transferred by an intermediate transfer member cleaning device 19a as an intermediate transfer member cleaning means provided opposite the driven roller 14e with the transfer belt 14a interposed therebetween. Will be cleaned.

In the above-described image forming apparatus, color image formation has been described, but image formation of only a monochrome image can be performed.

According to FIG. 3, the color image forming apparatus shown in FIG. 3 is a tandem type color image forming apparatus using an intermediate transfer member, and a transfer belt 14a as an intermediate transfer member.
Are provided from the upstream side in the rotation direction of the transfer belt 14a, four sets of color image forming process units 100 including black (K), cyan (C), magenta (M), and yellow (Y). K, C, M and Y
In the process unit 100, K using a light toner composed of a flat toner and a dark toner composed of a flat toner,
A superimposed toner image of flat toners of C, M and Y is formed, and the toner images of flat toner formed in each process unit 100 are superimposed and transferred on the transfer belt 14a. A superimposed color toner image of flat toner is formed on the transfer belt 14a, and the superimposed color toner image of flat toner transferred onto the transfer belt 14a is collectively transferred onto a transfer material and fixed. It is configured to be discharged outside.

Since the four process units 100 of K, C, M and Y all have a common structure, only one of them will be described.

The process unit 100 includes the photosensitive drum 10 and the photosensitive drum 1 as viewed from the transfer position of the toner image.
From the upstream side in the rotation direction of 0, a photoconductor cleaning device 19 for cleaning the transfer residual toner on the photoconductor drum 10, and a scorotron charger 11 (L) for light toner for forming a light toner image. Exposure optical system 12 (L) for light toner, developing device 13 (L) for light toner composed of flat toner, scorotron charger 11 (H) for dark toner for forming a dark toner image, dark toner And a developing unit 13 (H) for dark toner composed of flat toner.

The photosensitive drum 10 serving as an image forming body has a photoconductive layer of a conductive layer and an organic photosensitive layer (OPC) formed on the outer periphery of a cylindrical base using, for example, an aluminum pipe or an acrylic resin pipe. Things.

The photosensitive drum 10 is rotated in a counterclockwise direction indicated by an arrow with the conductive layer grounded by power from a drive source (not shown) or by the transfer belt 14a.

Charging means for light toner (first charging means)
And a scorotron charger 11 (H) serving as a charging means (second charging means) for dark toner, respectively, in a direction orthogonal to the moving direction of the photosensitive drum 10. The photoconductor drum 10 is attached to face and close to the photoconductor drum 10, and gives a uniform potential to the photoconductor drum 10 by corona discharge having the same polarity as the toner.

The exposure optical system 12 (L), which is an image exposure means (first image exposure means) for light toner, and the exposure optical system 12 (L) which is an image exposure means (second image exposure means) for dark toner H)
Each uses a scanning optical system that performs scanning in parallel with the rotation axis of the photosensitive drum 10 using, for example, a polygon mirror. The exposure optical system 12 (L) uses external exposure,
First image writing (first image writing) using image data for light toner
Image writing means for performing image exposure
(H) is an image writing unit that writes a second image (second image exposure) using image data for dark toner using external exposure.

The developing unit 13 (L), which is a developing means (first developing means) for light toner composed of flat toner or for flat toner and magnetic carrier, comprises a developer for light toner composed of flat toner, Alternatively, a first reversal development is carried out by contact or non-contact with a built-in developer composed of a light toner flat toner and a magnetic carrier. The developing device 13 (H), which is a developing means for dark toner composed of flat toner or for flat toner and magnetic carrier, is a developer for dark toner composed of flat toner, or a flat toner for dark toner and magnetic carrier. And the second reversal development is performed by contact or non-contact development.

In forming an image, image data for each color is divided into light toner image data and dark toner image data. First, the light toner scorotron charger 11 (L) uniformly charges the image data. Photoreceptor drum 10
Then, a first image exposure using image data for the light toner is performed by the exposure optical system 12 (L) to form a latent image of the light toner, and is made of flat toner, or made of flat toner and magnetic carrier. Developing unit 13 (L) for light toner
The first development with light toner composed of flat toner is performed by the development sleeve 131 (L). Next, the photosensitive drum 1 on which a light toner image made of flat toner is formed
At 0, the highest charging is performed by the scorotron charger 11 (H) for the dark toner, and the second charging is performed based on the dark toner image data.
Is performed by the exposure optical system 12 (H),
A latent image of the dark toner is formed, and the developing sleeve 131 (H) of the developing unit 13 (H) for the dark toner composed of the flat toner or the flat toner and the magnetic carrier is used to form the latent image of the flat toner. 2 is performed, and a toner image made of dark toner made of flat toner is formed on the photosensitive drum 10 on the toner image made of light toner made of flat toner. The light and dark toner images (superimposed toner images) made of the flat toner are transferred onto the transfer belt 14a at the transfer position of the first transfer unit.

The untransferred toner remaining on the photosensitive drum 10 after the transfer is cleaned by a photosensitive member cleaning device 19 that electrostatically collects the remaining toner.

The transfer belt 14a as an intermediate transfer member in which four process units 100 of K, C, M and Y face in parallel has a volume resistivity of 10 ¹⁰ to 10 ¹⁵ Ω · cm and a surface resistivity of 10 It is an endless belt of ¹⁰ to 10 ¹⁵ Ω / □,
For example, a modified polyimide, a thermosetting polyimide, an ethylene tetrafluoroethylene copolymer, polyvinylidene fluoride, a conductive material dispersed in an engineering plastic such as nylon alloy, the outside of a semiconductive film substrate having a thickness of 0.1 to 1.0 mm. Preferably, the seamless belt has a two-layer structure in which a fluorine coating having a thickness of 5 to 50 μm is applied as a toner filming preventing layer. In addition to the above, the transfer belt 14a has a thickness of 0.5 in which a conductive material is dispersed in silicon rubber or urethane rubber.
A semiconductive rubber belt of ~ 2.0 mm can also be used. The transfer belt 14a is stretched in contact with a driving roller 14d, a driven roller 14e, a tension roller 14k, and a backup roller 14j. During image formation, the transfer belt 14a is driven by a driving motor (not shown).
Are rotated, and the primary transfer roller 14 is moved at the transfer position for each color.
The transfer belt 14a is pressed against the photosensitive drum 10 by c, and the transfer belt 14a is rotated in the direction indicated by the arrow in the figure.

A primary transfer roller 14c, which is a roller member serving as a first transfer means of K, C, M and Y, is provided opposite to each photosensitive drum 10 with a transfer belt 14a interposed therebetween. Each transfer area (no symbol) is formed between the photoconductor drum 14a and each photoconductor drum 10. Each one
By applying a DC voltage having a polarity opposite to that of the toner (positive polarity in the present embodiment) to the next transfer roller 14c and forming a transfer electric field in a transfer area (no sign),
Light and dark toner images made of flat toner on the C, M and Y photoconductor drums 10 are transferred onto the transfer belt 14a.

The static eliminator 14n, which is a static eliminator for each color,
Preferably, the transfer belt 14a is constituted by a corona discharger, and charges the transfer belt 14a charged by the primary transfer roller 14c.

The process unit 1 of black (K) is started by starting a photoconductor drive motor (not shown) by starting image recording.
00 is rotated in the direction indicated by the arrow in the figure, and at the same time, a scorotron charger 11 for K light toner
The application of the potential to the K photoconductor drum 10 is started by the charging action (L).

After a potential is applied to the K photosensitive drum 10, the K light toner exposure optical system 12 (L) is used to control the electric charge corresponding to the K light toner image data of the first color signal. The first image exposure in the external exposure is started by the signal, and an electrostatic latent image for light toner corresponding to the K image of the original image is formed on the surface of the K photosensitive drum 10.

The latent image for the light toner is firstly brought into contact with the developing unit 13 (L) for the light toner composed of the flat toner of K, or the flat toner and the magnetic carrier.
Is performed, and a toner image is formed by the light toner composed of the K flat toner according to the rotation of the K photoconductor drum 10. Next, a scorotron charger 1 for the dark toner of K
1 (H) and exposure optical system 1 for K dark toner
2 (H), the electrostatic latent image for the dark toner corresponding to the K image by the second image exposure in the external exposure by the electric signal corresponding to the image data for the dark toner of K of the first color signal. Image forming and developing unit 13 for dark toner comprising flat toner of K or flat toner and magnetic carrier
By the second development according to (H), the toner image of the dark toner composed of the flat K toner is formed on the previously formed toner image of the light toner composed of the flat K toner.

The K toner image formed of the light and dark toners using the flat toner (the superposed toner formed of the flat toner) is formed on the K photoreceptor drum 10 as the image forming body by the image forming process described above. Image) in the K transfer area (no sign), the K primary transfer roller 14
c, the image is transferred onto the transfer belt 14a.

Next, the transfer belt 14a is synchronized with the C toner image, and the cyan (C) process unit 10
0 corresponds to image data for C light and dark toners formed on the C photoreceptor drum 10 by the second color signal, and a toner image composed of C light and dark toners using flat toner, respectively. A superimposed toner image made of flat toner) is made of dark and light K toners using flat toner on the transfer belt 14a by the C primary transfer roller 14c in the C transfer area (no symbol). It is formed on a transfer belt 14a by superimposing on a toner image (an overlaid toner image made of flat toner).

By the same process, the image is synchronized with the superposed toner images of K and C, and is formed on the photosensitive drum 10 of M by the process unit 100 of magenta (M). Corresponding to image data for light and dark toners of M,
A toner image composed of dark toner (a superimposed toner image composed of flat toner) is transferred to the M primary transfer roller 14c in the M transfer area (no symbol) by the K primary and flat toner of the transfer belt 14a. Are formed on the transfer belt 14a from the top of the superimposed toner image, and are synchronized with the superposed toner image composed of flat toners of K, C, and M, and yellow (Y)
Y photosensitive drum 10 by the process unit 100
A toner image composed of Y light and dark toners using flat toner corresponding to the Y light and dark toner image data formed by the fourth color signal formed above (superimposed toner composed of flat toners) Image), Y transfer area (no sign)
, The Y primary transfer roller 14c is formed on the transfer belt 14a by superimposing the K, C, and M flat toners on the transfer belt 14a. A superimposed color toner image of K, C, M, and Y made of flat toner is formed on the top.

After transfer, the untransferred toner remaining on the peripheral surface of each photosensitive drum 10 is cleaned by a cleaning device 19 as each image forming body cleaning means.

In synchronization with the formation of the superposed color toner images on the transfer belt 14a, the transfer material (recording material) is mainly transferred from a paper feed cassette 15 as a transfer material storage means via a timing roller 16 as a transfer material feeding means. The recording paper P used as the secondary transfer unit 14 is used as the second transfer unit.
g is transferred to a transfer area (no sign), and a superimposed color toner image composed of flat toner on the transfer belt 14a is formed on the recording paper P by a secondary transfer device 14g to which a DC voltage having a polarity opposite to that of the toner is applied. It is transcribed all at once.

The recording paper P to which the superimposed color toner image made of flat toner has been transferred is neutralized by the neutralizing electrode 16b which is a separating means formed of a sawtooth electrode plate, and is conveyed to the fixing device 17.

The fixing device 17 includes a fixing roller 17a as a fixing roller member (a roller member provided on the surface of the transfer material having the toner image) for fixing the superimposed color toner image made of flat toner, and a fixing device. Roller 17a
And a pressure roller 17b as a pressure roller member (a roller member provided on the surface of the transfer material on the side not having the toner image). Fixing roller 17
a, a halogen lamp H serving as a heating means having a heating filament (no symbol) as a heating source.
La is provided.

After the superimposed color toner image composed of the flat toner on the recording paper P is fixed by applying heat and pressure between the fixing roller 17a and the pressure roller 17b, it is sent by the discharge roller 18. It is discharged to the tray at the top of the device.

The untransferred toner remaining on the peripheral surface of the transfer belt 14a after the transfer is transferred by an intermediate transfer member cleaning device 19a as an intermediate transfer member cleaning means provided opposite the driven roller 14e with the transfer belt 14a interposed therebetween. Will be cleaned.

In the above-described image forming apparatus, color image formation has been described, but image formation of only a monochrome image can be performed.

Next, a flat toner for a one-component developer or a flat toner for a two-component developer and a magnetic carrier (spherical carrier or flat carrier) used for forming a toner image in each image forming apparatus described above. This will be described with reference to FIGS. 4 is a schematic diagram illustrating an example of a flat toner, FIG. 5 is a cross-sectional view of a main part illustrating an example of an annular continuous wet stirring mill, and FIG. 6 is a schematic diagram of a flat-shaped magnetic carrier. is there.

According to FIG. 4 or FIG. 5, flat toner (flat particles) used in the developer of each image forming apparatus of the present invention.
Is a spherical particle made by emulsion polymerization or suspension polymerization,
It can be manufactured by flattening with heat and external pressure.

The volume average particle diameter of the flat toner is 3 to 10 μm.
And more preferably 4 to 9 μm.

The flat toner preferably has a specific shape. That is, the long side (R1) of the average length of the flat toner
And the short side (R2) is 5 to 20 μm, and the average thickness (d) is 1 to
Preferably it is 5 μm. The ratio of the short side to the long side (R2 / R1) of the average length is preferably 0.6 to 1.0, and 0.8 to 1.0.
1.0 is more preferred. The average thickness to average short side length ratio (d / R2) of the toner is preferably from 0.1 to 0.5, and more preferably from 0.2 to 0.4.

In fact, when such a flat toner is used, when a color image (printing rate 25%) is formed by each of the above-described image forming apparatuses, the toner consumption per A-4 size print is 20 to 40 mg. Even if the amount is extremely small, a high-density image without unevenness can be obtained, and a print-like image quality without toner scattering can be obtained.

The average length (R1, R2) of the flat toner is 5
If it is less than μm, diseases such as pneumoconiosis may be caused, which is not preferable in terms of safety and hygiene. If it exceeds 20 μm, developability decreases, faithful development cannot be performed, and the resolving power decreases, which is not preferable.

The ratio of the long side to the short side of the average length of the flat toner (R
When 2 / R1) is less than 0.8, and especially less than 0.6, the flat portion of the flat toner hardly adheres to the image forming body, the toner layer becomes thicker, the toner consumption increases, and the transfer,
It is not preferable because toner scattering and toner spread in the fixing step increase.

If the average thickness (d) of the flat toner is less than 1 μm, the flat toner is crushed at the time of development, and ultrafine powder is generated, causing toner scattering and fogging. If it exceeds 5 μm, it is not preferable. Is difficult to develop in a layered form, and the toner layer becomes thicker, and the amount of consumed toner is increased.

When the average thickness to average short side length ratio (d / R2) of the flat toner is 0.2 or less, particularly less than 0.1, the flat toner is crushed at the time of development, and ultrafine powder is generated, and toner scattering occurs. When the ratio exceeds 0.4, especially 0.5, the flat portion of the toner hardly adheres to the image forming body, the toner layer is hardly developed in a layer form, and the toner layer becomes thick. It is not preferable because toner consumption increases. In addition, toner scattering and toner spread also increase in the transfer and fixing steps, which is not preferable.

When the flat toner is formed into the above-described shape, development is performed using the flat toner, and a toner image is formed on an image forming body (photosensitive drum). With the flat portion facing the image forming body, and adheres in a more layered manner. Further, when the flat toner is transferred from the image forming body to the intermediate transfer body (transfer belt), the flat part of the flat toner adheres in a layer shape toward the intermediate transfer body. In particular, when using recording paper as a transfer material (recording material),
Since the recording paper is composed of fibers and the surface has irregularities, the surface and the inside are electrically non-uniform,
Since the change in electrical characteristics due to humidity is large, the transfer material (recording paper) from the image forming body or the transfer material (recording paper) from the intermediate transfer body
At the time of transfer to the surface, the flat toner adhered state tends to be disordered.

The surface charge state of the flat toner is substantially uniformly charged. For this reason, the Coulomb force between the image forming body and the flat portion of the flat toner is higher than that of the flat toner end portion. Is considered to be attached. In this way, the flat toner on the image forming body and on the intermediate transfer body is arranged in the horizontal direction with the edges thereof laid down, and the flat toners are easily overlapped with each other in flat layers, so that a stable toner image can be maintained even when moved. Conceivable. Particularly in color image formation, since the toner images of the respective colors are superimposed, it is necessary to superimpose the toner images of the respective colors in layers on flat surfaces and on an intermediate transfer member having a uniform electric characteristic. It is an important component for obtaining a good image. In this manner, it is preferable to superimpose toner images on an image forming body or an intermediate transfer body in a large number of times, and to reduce the number of times of transfer onto a transfer material (recording paper) having large surface irregularities and large changes in electrical characteristics. Become.

A toner having an insufficient flatness or an irregular toner has a flattened portion that cannot be laid down uniformly and is in a random adhesion state, and toner scattering and spread of a toner image in a transfer and fixing process become large. Was observed.

Even when flat toner is used, in the tandem system in which the toner is transferred onto a transfer material (recording paper) every time, toner scattering and toner spread in the transfer process were observed to a lesser extent than the irregular toner.

The toner having an insufficient flatness or an irregular toner has a shape deviating from the flat toner shape defined as described above. The toner is produced by a pulverization method or is not subjected to a flattening treatment by a polymerization method. The prepared toner and the like correspond.

Hereinafter, a method for producing flat toner (flat particles) will be specifically described. The flat toner used as a developer in each image forming apparatus of the present invention is obtained by salting out / fusing resin particles having a number average primary particle diameter of 10 to 500 nm produced by a suspension polymerization method or an emulsion polymerization method. Next particles are produced, and then an organic solvent, a coagulant and a polymerization catalyst are added to perform polymerization,
The spherical secondary particles (spherical toner) in the solution having a polymerization rate of up to 80% are circulated through a pressurized bottleneck while being heated together with the solution to flatten the particle shape, and furthermore, the polymerization catalyst is used. It can be produced by adding and completing the polymerization.

The salting out / fusing means that the resin fine particles produced in the polymerization step are salted out with an aggregating agent, excess dispersing agents, surfactants, etc. are removed, and at the same time, the size of the resin particles is heated and fused. Adjusting.

The flattening treatment may be performed after the polymerization is completed to 100%. However, the shape is more uniform if the flattening treatment is performed after the spheroidization is performed with the polymerization progressing to 80%. Is preferable.

The number-average primary particles are light scattering electrophoresis particle size analyzer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.).
Can be measured.

The volume average particle size was measured using a Coulter counter TA.
-2 or Coulter Multisizer (manufactured by Coulter Inc.).

The salting-out / fusion may be performed by mixing the resin particles with a dispersion of a releasing agent or a coloring agent necessary for forming the toner, or by mixing the releasing agent or the coloring agent in the monomer. Number average primary particle size 1 prepared by a method such as emulsion polymerization after dispersing the components
It can be carried out by salting out / fusing resin particles of 0 to 500 nm.

That is, various constituent materials such as a colorant and, if necessary, a release agent, a charge control agent, and a polymerization initiator are added to the polymerizable monomer, and a homogenizer, a sand mill, a sand grinder, and an ultrasonic disperser are added. Various constituent materials are dissolved or dispersed in the polymerizable monomer by a machine or the like. The liquid in which the various constituent materials are dissolved or dispersed is dispersed in an oil medium having a desired size as a toner in an aqueous medium containing a dispersion stabilizer using a homomixer or a homogenizer. afterwards,
The mixture is transferred to a reactor equipped with a stirring mechanism having stirring blades, and heated so that the polymerization reaction proceeds up to 80% to form spherical particles (spherical toner). Thereafter, the heated bottle is circulated through a pressurized bottleneck to flatten the shape, and a polymerization catalyst is added to proceed with the polymerization, thereby completing the polymerization. After the polymerization is completed, the dispersion stabilizer is removed, filtered, washed, and dried to obtain a flat toner used as a developer in each image forming apparatus of the present invention.

As shown in FIG. 5, an example of an annular type continuous wet stirring mill is a kind of a known mill, and is an annular (annular) stator 50 having a triangular cross section.
1, a rotor 502 having substantially the same shape rotates, and a narrow gap between the stator 501 and the rotor 502, that is, a crushing zone 503 is filled with a medium 504 and supplied to a mill. % Of the secondary particles (spherical toner) in the solution having undergone polymerization to a mechanical impact force together with the solution containing the secondary particles to flatten the shape of the secondary particles. The solution passes through the crushing zone 503 having a W-shaped cross section by a pump from a supply port 505 of the mill, is separated from a medium 504 by an upper cap separator 506, and is discharged from an outlet 507. The temperature of the solution during the flattening process is controlled by circulating hot water 508 through the stator and the rotor. The media 504 sequentially moves through the W-shaped pulverizing zone due to centrifugal force, and returns to the entrance and circulates again. Pressure on the particles is applied by the walls or media of the grinding zone by circulating through a pressurized bottleneck. As the medium, zircon, glass, steel or the like having a diameter of 0.5 to 3 mm is usually used.

The flattening temperature of the solution containing the secondary particles using such an annular continuous wet stirring mill is preferably −5 ° C. to + 40 ° C. of the glass transition point (Tg) of the resin of the secondary particles, and 0 ° C. To + 30 ° C, more preferably +10 to + 30 ° C. 5 than the glass transition point
If the treatment is performed at a temperature lower than or equal to ° C., the polymer particles are crushed, and it is difficult to perform the intended flattening, which is not preferable. On the other hand, when the treatment is performed at a temperature higher than the glass transition point by 40 ° C. or more, the secondary particles fuse with each other to form agglomerates, and the flattened polymer particles are again spheroidized by their surface tension. Therefore, flattening cannot be performed efficiently, which is not preferable.

Examples of the polymerizable monomer constituting a resin as a binder include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, and p-chlorostyrene. , 3,4-dichlorostyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene,
Styrenes such as p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, styrene derivatives, methacrylic acid Methyl, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, Methacrylate derivatives such as diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate,
Acrylate derivative such as isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, phenyl acrylate, etc .; olefins such as ethylene, propylene, isobutylene, vinyl chloride, vinylidene chloride Vinyl halides such as vinyl bromide, vinyl fluoride, vinylidene fluoride, vinyl esters such as vinyl propionate, vinyl acetate and vinyl benzoate; vinyl ethers such as vinyl methyl ether and vinyl ethyl ether; vinyl methyl ketone , Vinyl ethyl ketone, vinyl hexyl ketone, and other vinyl ketones, N-vinyl carbazole, N-vinyl indole, N-vinyl pyrrolidone, and other N-vinyl compounds, vinyl naphthalene, vinyl pyridine, and other vinyl compounds Acrylonitrile, methacrylonitrile, acrylic acid or methacrylic acid derivatives of acrylamide. Among them, vinyl monomers can be used alone or in combination.

Further, it is more preferable to use a polymerizable monomer constituting the resin in combination with one having an ionic dissociation group. For example, those having a substituent such as a carboxyl group, a sulfonic acid group, and a phosphate group as a constituent group of the monomer, specifically, acrylic acid, methacrylic acid,
Maleic acid, itaconic acid, cinnamic acid, fumaric acid, monoalkyl maleate, monoalkyl itaconate, styrenesulfonic acid, allylsulfosuccinic acid, 2-acrylamido-2-methylpropanesulfonic acid, acid phosphooxyethyl Methacrylate,
3-chloro-2-acid phosphooxypropyl methacrylate and the like.

Further, divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate,
Polyfunctional vinyls such as neopentyl glycol diacrylate can be used to form a crosslinked resin.

These polymerizable monomers can be polymerized using a radical polymerization initiator. In this case, an oil-soluble polymerization initiator can be used in the suspension polymerization method. As the oil-soluble polymerization initiator, 2,2'-azobis- (2,2
4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 1,1'-azobis (cyclohexane-1-carbonitrile), 2,2'-azobis-4-
Azo or diazo polymerization initiators such as methoxy-2,4-dimethylvaleronitrile and azobisisobutyronitrile, benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroperoxide, t-butyl hydroperoxide , Di-t-butyl peroxide, dicumyl peroxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide, 2,2-bis-
Examples include peroxide-based polymerization initiators such as (4,4-t-butylperoxycyclohexyl) propane and tris- (t-butylperoxy) triazine, and polymer initiators having a peroxide in a side chain. .

When the emulsion polymerization method is used, a water-soluble radical polymerization initiator can be used. Examples of the water-soluble polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate, azobisaminodipropane acetate, azobiscyanovaleric acid and salts thereof, and hydrogen peroxide.

The dispersion stabilizers include tricalcium phosphate, magnesium phosphate, zinc phosphate, aluminum phosphate, calcium carbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, and calcium sulfate. , Barium sulfate,
Bentonite, silica, alumina and the like can be mentioned. Further, those generally used as surfactants such as polyvinyl alcohol, gelatin, methyl cellulose, sodium dodecylbenzenesulfonate, ethylene oxide adduct, and higher alcohol sodium sulfate can be used as the dispersion stabilizer.

As the resin excellent in the present invention, a resin having a glass transition point of 20 to 90 ° C. is preferable and a softening point of 8
The thing of 0-220 ° C is preferred. The glass transition point is measured by a differential calorimetric analysis method, and the softening point can be measured by a Koka type flow tester. Furthermore, these resins have a number average molecular weight (Mn) of 10 as measured by gel permeation chromatography.
00 to 100000, weight average molecular weight (Mw) 200
Those having 0 to 1,000,000 are preferred. Further, as a molecular weight distribution, Mw / Mn is 1.5 to 100, particularly 1.8.
-70 are preferred.

The flat toner used in each image forming apparatus of the present invention contains at least a resin and a colorant, but may contain a releasing agent or a charge control agent as a fixability improving agent as required. You can do it. Further, an external additive composed of inorganic fine particles or organic fine particles may be added to the particles of the flat toner mainly composed of the above-mentioned resin and colorant.

As the colorant used in the flat toner used in the image forming apparatus of the present invention, carbon black, dyes, pigments and the like can be optionally used.

As carbon black, channel black, furnace black, acetylene black, thermal black, lamp black and the like can be used.

As the dye, C.I. I. Solvent Red 1, 49, 52, 58, 63, 111, 1
22, C.I. I. Solvent Yellow 19, 44, 7
7, 79, 81, 82, 93, 98, 10
3, 104, 112, 162, C.I. I. Solvent Blue 25, 36, 60, 70, 93, 9
5 and the like, and a mixture thereof can also be used. Examples of the pigment include C.I. I. Pigment Red 5, 48: 1, 53: 1, 57: 1, 122,
139, 144, 149, 166, 177,
178, 222, C.I. I. Pigment Orange 3
1, 43, C.I. I. Pigment Yellow 14, 1
7, 93, 94, 138, C.I. I. Pigment Green 7, C.I. I. Pigment Blue 15: 3, 60
Etc. can be used. The above dyes and pigments can be used alone or as a mixture. Although the number average primary particle size of the colorant varies depending on the type, it is generally 10 to 200 nm.
Is preferred.

As a method of adding a colorant, a method of adding a colorant at the stage of polymerizing a monomer and polymerizing it to obtain colored particles can be used. When the colorant is added at the stage of preparing the polymer, it is preferable to use the colorant after treating the surface with a coupling agent or the like so as not to inhibit the radical polymerizability.

Further, low molecular weight polypropylene (number average molecular weight = 1500 to 9000) or low molecular weight polyethylene as a fixing property improving agent may be added.

The charge control agents are also various known ones.
In addition, those that can be dispersed in water can be used. Specifically, nigrosine dyes, metal salts of naphthenic acid or higher fatty acids, alkoxylated amines,
Quaternary ammonium salt compounds, azo-based metal complexes, salicylic acid metal salts or metal complexes thereof.

The particles of the charge controlling agent and the fixability improving agent have a number average primary particle diameter of 10 to 500 in a dispersed state.
It is preferable to set it to about nm.

The flattening of the spherical secondary particles obtained by salting out / fusing can be performed by an annular type continuous wet stirring mill, a piston type high-pressure homogenizer, an in-line screw pump or the like.

Further, in the flat toner used in the developer of each image forming apparatus of the present invention, the effect can be more exerted by adding and using fine particles such as inorganic fine particles and organic fine particles as external additives. . It is presumed that the reason for this is that since the burying and desorption of the external additive can be effectively suppressed, the effect is remarkable.

As the inorganic fine particles, it is preferable to use inorganic oxide particles such as silica, titania and alumina.
Further, it is preferable that these inorganic fine particles have been subjected to a hydrophobic treatment with a silane coupling agent, a titanium coupling agent, or the like. The degree of the hydrophobic treatment is not particularly limited, but a methanol wettability of 40 to 95 is preferable. Methanol wettability is to evaluate the wettability to methanol. In this method, 0.2 g of the inorganic fine particles to be measured is weighed and added to 50 ml of distilled water placed in a 200 ml beaker. Methanol is slowly dropped from a buret whose tip is immersed in the liquid until the whole of the inorganic fine particles is wet while being slowly stirred. When the amount of methanol required to completely wet the inorganic fine particles is a (ml), the degree of hydrophobicity is calculated by the following equation.

Degree of hydrophobicity = (a / (a + 50)) × 100
The amount of the external additive added is 0.1 to 0.1 in the flat toner.
5.0 mass% is preferred, and more preferably 0.5-4.
0% by mass. Various external additives may be used in combination.

According to FIG. 6, the magnetic carrier used in the developer of each image forming apparatus of the present invention is a spherical magnetic carrier or a flat magnetic carrier having a shape obtained by crushing a spherical carrier. As shown in FIG. 6, the thickness of the particles of the flat magnetic carrier (flat carrier) is D,
When the major axis of the planar shape is D1 and the minor axis is D2, the relationship is D1 / D = 2 to 5, D1 / D2 = 1 to 1.5, and when D1 / D is 2 or less, a spherical carrier is used. It is difficult to recognize the difference between the above effects and when it is 5 or more, a decrease in the performance as a carrier is observed. Also, it is desired that the planar shape is close to a circle. As for the size of the carrier particles, particles having a major axis D1 of 30 to 100 μm are appropriate.
When the carrier is made of a magnetic material having a small magnetic anisotropy, the flat magnetic carrier can have an easy axis of magnetization within a flat plane due to its shape. Therefore, when a plurality of flat magnetic carrier particles (flat carriers) are dispersed in a magnetic field facing the magnetic poles, as described in detail in a later stage, the flat portions (flat surfaces) of the flat magnetic carrier particles (flat carriers) are formed. The ends form a brush-shaped ear (magnetic brush) connected.

The flat magnetic carrier particles (flat carriers) can be manufactured as flat ferrite carriers by the firing method described below.

Mixing NiO and ZnO with iron oxide
After sintering at 00 ° C. and partially promoting spinelization and crystal growth, wet grinding is performed to an average particle size of 1.0 to 1.5 μm. The physical properties of the slurry after pulverization have a significant effect on the size and shape of the particles in the next granulation and firing steps, the spinelization reaction and the crystal growth, so that the slurry can be adjusted by controlling the temperature, viscosity, dispersibility, etc. Done.

In the next granulation / drying step, the slurry is granulated with a spray drier and dried with hot air.
In the granulation process, provide a process of simultaneously drying and deforming by means such as spraying strongly on a heated iron plate, or flatten by passing spherical particles after pressure drying between pressure rollers. Can be. In order to flatten the particle shape and obtain a desired particle size and particle size distribution, it becomes possible by controlling the type and amount of the binder, the temperature, and the amount of air.

After classification, firing is performed at a temperature of 1200 ° C. or more while controlling the temperature and atmosphere to obtain a complete ferrite spinel structure, and a ferrite carrier having desired magnetic and electrical properties can be obtained. The obtained ferrite carrier is obtained by removing non-magnetic substances by a magnetic separator and finally classifying a ferrite carrier having the above-mentioned particle size distribution in a classification step.

The flat magnetic carrier (flat carrier) can be manufactured by flattening in the process of forming resin particles containing magnetic powder by a polymerization method. In this case, the amount of the magnetic powder contained in the resin particles is determined depending on the magnetic properties required as a carrier, but the amount is preferably 50 to 90% by mass.

As the magnetic powder used for the flat magnetic carrier (flat carrier), any conventionally used magnetic substance can be used. The magnetic material is a ferromagnetic element or an alloy or compound containing these, such as a compound such as magnetite, maghemite, or ferrite, a metal such as iron, cobalt, nickel, or manganese, or an alloy thereof.
From the viewpoint of improving the dispersibility of the magnetic powder, a spherical magnetic powder can be preferably used. The spherical magnetic powder has a ratio of a major axis to a minor axis of 0.9 or more measured using a scanning electron microscope or a transmission electron microscope. In addition,
Examples of the shape of the magnetic powder itself include a sphere, an octahedron, and a cube. In order to disperse the magnetic powder in a resin or a monomer, it is preferable to use lecithin or various coupling agents together or to perform a surface treatment.

Next, an example of preparing a magnetic carrier will be described. Spherical magnetic powder 600 having a number average primary particle diameter of 0.2 μm
0.1 parts by mass of lecithin was added to 30 parts by mass of styrene monomer, 165 parts by mass of styrene monomer, and 35 parts by mass of n-butyl acrylate, followed by dispersion with a sand grinder at room temperature for 30 minutes. This was prepared by adding 3 parts by mass of 2,2'-azobis (2,4-dimethylvaleronitrile) as a polymerization initiator to this. Then, 710 parts by mass of ion-exchanged water and 0.1 part by mass were placed in a four-necked flask equipped with a high-speed stirring device (TK homomixer).
600 parts by mass of an aqueous trisodium phosphate solution (mol / liter) were added, the mixture was heated to 65 ° C., and 120 parts by mass of a 1.0 mol / l aqueous solution of calcium chloride was gradually added under stirring conditions at a rotation speed of 5000 rpm. An aqueous dispersion medium containing a dispersion containing tricalcium was prepared. Further, 0.1 part by mass of sodium dodecylbenzenesulfonate is added, and a dispersion obtained by dispersing the magnetic powder in the monomer is gradually added to the aqueous dispersion medium under stirring conditions at a rotation speed of 5000 rpm, and the magnetic powder is added to water. The monomers contained were dispersed. The polymerization reaction was carried out under a nitrogen stream at 65 ° C. and 200 rpm under stirring conditions for 5 hours. When the polymerization addition rate reached 69%, the mixture was supplied to an annular continuous disperser (Kobol Mill manufactured by Shinko Faudler Co., Ltd.). The mixture was stirred at a temperature of 70 ° C. at a peripheral speed of 13 m / sec to make it flat. Thereafter, the mixture was transferred from an annular type disperser to a flask and reacted at 85 ° C. for 2 hours to complete the polymerization reaction. At the end of the polymerization reaction, hydrochloric acid was added to remove tricalcium phosphate as a dispersion stabilizer, followed by filtration, washing and drying to prepare flat magnetic carrier particles having a volume average particle size of 48 μm (using a Coulter Counter Multisizer). The flat magnetic carrier particles thus obtained were flat magnetic carrier particles (flat carriers) having the shape shown in FIG.

The surface of the flat magnetic carrier particles (flat carrier) obtained by the above-mentioned firing method has a styrene resin, vinyl resin, ethylene resin, rosin modified resin, acrylic resin, polyamide resin, epoxy resin. , A polyester resin, a silicon resin, a fluorine resin, or the like.

In general, if the average particle size of the magnetic carrier particles is large, the condition of the ears of the magnetic brush formed on the developer carrying member (developing sleeve) becomes coarse. Has a problem that the toner image tends to show unevenness and the toner concentration in the ears is low, so that high-density development is not performed. This problem can be solved by reducing the average particle size of the magnetic carrier particles. As a result of the experiment, the above problem does not occur if the long diameter D1 of the flat magnetic carrier particles (flat carrier) is 30 to 100 μm. There was found.

If the major axis D1 is 30 μm or less, it is difficult to sufficiently magnetize the flat magnetic carrier particles (flat carriers), and the magnetic carrier particles adhere to the surface of the photosensitive drum together with the toner particles or are easily scattered. Become.

Further, when the major axis D1 is 100 μm or more, the specific surface area of the carrier becomes small, so that the toner (the flat toner described above) cannot be sufficiently charged.
Further, since the covering ratio is high, toner scattering is also likely to occur.

Generally, the magnetic particles (magnetic carrier) are easily magnetized and adsorbed in the in-plane direction. However, since the magnetic particles (magnetic carrier) are flattened, there is no in-plane direction due to the flattening. Therefore, the layer is formed uniformly, and the occurrence of a locally low-resistance region or unevenness in the layer thickness is prevented. In addition, since the magnetic particles (magnetic carrier) are flattened, the resistance of the ionic particles is increased, and the edges as seen in the conventional particles are eliminated, so that the electric field does not concentrate on the edges. As a result, even when a high bias voltage is applied, development unevenness does not occur. The volume resistivity of the magnetic particles (magnetic carrier) of the spherical carrier or the flat carrier exhibiting the above-mentioned effects is 10 ⁸ Ω · cm or more, especially 10 ¹² Ω · cm.
What formed the magnetic particle so that it might be more than ohm * cm is preferable. The volume resistivity after tapping putting particles in a container having a sectional area of 0.50 cm ^2, a load of 1 kg / cm ² on packed particles, 1000V between the load and a bottom electrode / It is a value that can be obtained by reading the current value when applying a voltage that produces an electric field of cm.
When the volume resistivity is low, when a bias voltage is applied to the developer carrying body (developing sleeve), electric charges are injected into the magnetic carrier, so that the magnetic carrier easily adheres to the surface of the image carrier, or the bias voltage breaks. Down is likely to occur.

Magnetization strength of magnetic carrier (maximum magnetization)
Is 10 to 60 emu / g, preferably 15 to 40 em
u / g. Although this strength depends on the magnetic flux density on the developer carrying body (developing sleeve), under a general condition of the magnetic flux density of the developer carrying body, at less than 10 emu / g, the magnetic binding force does not work. It causes carrier scattering. In addition, if it exceeds 60 emu / g, in non-contact development in which the ears of the carrier become too high, it is difficult to maintain a non-contact state with the image carrier. In contact development, sweeping lines are likely to appear on the toner image.

As the spherical carrier used for the magnetic carrier, a spherical toner having a volume average particle diameter of 3 to 10 μm is preferably used, and a polymerized toner by an emulsion polymerization association method is used. In the method for producing a polymerized toner by the emulsion polymerization association method, first, a colorant is dispersed in water using a surfactant. On the other hand, a surfactant, an emulsion polymerization initiator, a styrene monomer and an acrylic monomer are added to water, and a resin emulsion is formed by emulsion polymerization. Next, the colorant dispersion and the resin emulsion are mixed and slowly aggregated while balancing the repulsive force of the particle surface generated by pH adjustment and the cohesive force due to the addition of the electrolyte. At the same time, by heating and stirring, fusion and shape control between the fine particles are performed. The stirring at this time is performed by heating and stirring using a stirring tank designed to be stirred in a laminar flow state without turbulence, thereby performing fusion and shape control between the fine particles, and filtering, washing, and filtering the obtained particles. Dry to a volume average particle size of 3
A spherical toner having a desired particle size of 10 to 10 μm is obtained.

The toner obtained by the emulsion polymerization association method thus obtained has a sharp particle size distribution and a small amount of fine powder, reduces toner contamination of the carrier, so-called toner spent, improves the durability of the developer, and improves the charge amount distribution. Is uniform, and it is possible to obtain a high-quality image as compared with a conventional pulverized toner.

As the two-component developer used in each image forming apparatus of the present invention, the flat carrier particles (flat carrier) and the flat toner as described above have the same ratio as in the conventional two-component developer. When a general coating carrier (density of 5 to 8 g / cm ³ ) is used as a magnetic carrier using a spherical carrier or a flat carrier, the toner concentration in the developer is 2%. ３０30% by mass, preferably 5-2
0% by mass.

If the amount is less than 2% by mass, the number of toners required for development cannot be secured, and the coverage decreases, resulting in excessive charging and a decrease in developability.

When the content is more than 30% by mass, the coverage is large, and poor charging and toner scattering are likely to occur.

However, when a magnetic carrier of a resin dispersion type having a relatively light density (2 to 4 g / cm ³ ) as described above is used as the magnetic carrier in the developer, the toner concentration in the developer is a general value. Slightly higher than when a resin-coated magnetic carrier is used, 5 to 40% by mass, more preferably 10% by mass.
To 30% by mass.

The above-described two-component developer is mixed with a fluidizing agent for improving the fluid sliding of particles, a cleaning agent for cleaning the surface of the image carrier, and the like, if necessary. As the fluidizing agent, colloidal silica, silicon varnish, metal soap or nonionic surfactant can be used. As the cleaning agent, a surfactant such as fatty acid metal salt, organic group-substituted silicon or fluorine can be used. Is possible.

In each image forming apparatus of the present invention, development using a two-component developer of flat magnetic carrier particles (flat carrier) and flat toner (flat toner) can be performed in non-contact development. Also in the contact development, more excellent developability is exhibited as compared with the case where a spherical magnetic carrier (spherical carrier) and flat toner are used.

The developing means using the flat toner and the spherical carrier or the flat carrier will be described below with reference to FIGS. FIG. 7 is a schematic diagram of a two-component developer composed of a flat toner and a spherical carrier or a flat carrier. FIG. 8 is a cross-sectional configuration diagram of a contact developing type developing unit using a magnetic brush using a vertical magnetic field. FIG. 9 is a diagram showing the state of movement of the flat carrier by the pressing member, and FIG. 10 is a diagram showing the state of the magnetic brush of the two-component developer when performing contact development using the flat carrier. FIG. 12 is a diagram illustrating a state of a magnetic brush of a two-component developer when performing contact development using a spherical carrier. FIG. 12 is a cross-sectional configuration of a non-contact developing type developing unit using a magnetic brush using a horizontal magnetic field. FIG. 13 is a diagram illustrating a state of a magnetic brush of a two-component developer when performing non-contact development using a flat carrier, and FIG. 14 is a diagram illustrating a case where non-contact development is performed using a spherical carrier. Two-component developer Is a diagram showing a state of the magnetic brush, FIG. 15 is an explanatory view of the developing condition for preventing edge effects in two-component developer comprising a flat toner and flat carrier.

According to FIG. 7, the two-component developer is
A flat carrier as a flat magnetic carrier as shown in (A) and a flat toner having a flat surface adhered to the flat carrier, or as a spherical magnetic carrier as shown in FIG. It is composed of a spherical carrier and flat toner having a flat surface attached to the spherical carrier, and is used as a developer for contact development or non-contact development described below.

First, contact development using a two-component developer composed of flat toner and a magnetic carrier (spherical carrier or flat carrier) will be described.

According to FIGS. 8 to 11, in the developing device 13 as a developing means shown in FIG. 8, a developer accommodating portion 130 accommodates a two-component developer composed of a flat toner and a flat carrier as a magnetic carrier. , 132 is a magnet roll which is a magnetic field generating means having a fixed magnetic pole, and 131 (or 131 (H) or 131 (L)) is a developer which is a developer carrying member having a magnet roll 132 therein. The sleeve 133 is a layer thickness regulating member that is a layer thickness regulating unit made of a magnetic material that regulates the developer layer thickness on the developing sleeve 131 (or the developing sleeve 131 (H) or the developing sleeve 131 (L)) to a predetermined amount. 133A, a developer receiving member made of a non-magnetic material;
Numeral 34 denotes a leveling plate for leveling the developer whose layer thickness is regulated from the layer thickness regulating member 133. Reference numeral 138 denotes a developer removing plate having a magnet plate 138A on the back surface.
6,137 is a pair of stirring screws. Reference numeral 139 denotes a toner density detection sensor using, for example, a piezoelectric element or the like.

Developing Sleeve 131 as Developer Conveyor
The developing sleeve 131 (H) or the developing sleeve 131 (L) is made of a non-magnetic cylindrical member having an outer diameter of 8 mm to 60 mm using, for example, a stainless material, and is formed of the photosensitive drum 10 (or the photosensitive drum 10 a). ) To the developing sleeve 131 (or the developing sleeve 131).
(H) or a vertical magnetic field Ha formed by a magnetic pole N1 of a magnet roll 132 described later, while maintaining a predetermined gap (D _SD ) by abutting rollers (not shown) provided at both ends of the developing sleeve 131 (L)). Developing sleeve 131
(Or the developing sleeve 131 (H) or the developing sleeve 131 (L)) with the photosensitive drum 10
(Or the photosensitive drum 10a), and the photosensitive drum 10 (or the photosensitive drum 10
It is rotated in the same direction as the rotation of a). Developing sleeve 131
(Or the developing sleeve 131 (H) or the developing sleeve 131 (L)) to apply a magnetic brush to the photosensitive drum 10.
(Or the photosensitive drum 10a). If the outer diameter is 8 mm or less, it is impossible to form a magnet roll 132 having at least five magnetic poles composed of magnetic poles N1, S1, N2, S2, and N3 necessary for image formation. (Alternatively, the developing sleeve 131 (H) or the developing sleeve 13
If the outer diameter of 1 (L) exceeds 60 mm, the size of the developing device 13 increases. In particular, in a color printer having a plurality of developing units 13, the volume occupied by the developing units 13 is large, and the photosensitive drum 10 (or the photosensitive drum 10a) is used.
The image forming apparatus becomes larger due to an increase in the outer diameter of the photoconductor drum 10 or an increase in the size of the photoconductor drum 10 (or the photoconductor drum 10a).

The peripheral surface of the developing sleeve 131 (or the developing sleeve 131 (H) or the developing sleeve 131 (L)) may have a rough surface of 2 to 15 μm to perform a process for improving the developer transportability. preferable.

The magnet roll 132 is included in the developing sleeve 131 (or the developing sleeve 131 (H) or the developing sleeve 131 (L)) and includes a plurality of magnetic poles N.
1, N2, N3, S1, and S2 are alternately arranged, and are fixed concentrically with the developing sleeve 131 (or the developing sleeve 131 (H) or the developing sleeve 131 (L)). Apply magnetic force. The perpendicular magnetic field Ha formed by the magnetic pole N1 forms a magnetic brush that comes into contact with the photoconductor drum 10 (or the photoconductor drum 10a). The latent image on the photosensitive drum 10 (or the photosensitive drum 10a) is developed using a magnetic brush by the vertical magnetic field Ha, and the photosensitive drum 10 (or the photosensitive drum 10a) is developed.
A toner image is formed thereon.

The magnetic force on the peripheral surface of the developing sleeve 131 (or the developing sleeve 131 (H) or the developing sleeve 131 (L)) is between 500 and 1200 gauss. Necessary to form.

Layer thickness regulating member 133 as layer thickness regulating means
Is made of, for example, a bar-shaped or plate-shaped magnetic stainless steel, which faces the magnetic pole N3 of the magnet roll 132 and is disposed at a predetermined gap from the developing sleeve 131 (or the developing sleeve 131 (H) or the developing sleeve 131 (L)). The developing sleeve 131 (or the developing sleeve 131)
(H) or the layer thickness of the two-component developer on the peripheral surface of the developing sleeve 131 (L)).

The receiving member 133A is made of a non-magnetic member using a resin member such as an ABS resin, for example, and the developing sleeve 131 (or the developing sleeve 131 (H) or the developing sleeve 131 (H)) is provided on the downstream side in the rotation direction of the developing sleeve 131.
(L)) and a predetermined gap, and the layer thickness regulating member 133.
Is formed integrally with, for example, a layer thickness regulating member 133 with an adhesive to prevent toner spillage from the developer layer regulated by the layer thickness regulating member 133, and a two-component developer. Is stably kept on the peripheral surface of the developing sleeve 131 (or the developing sleeve 131 (H) or the developing sleeve 131 (L)). The receiving member 133A may be formed by the developing device housing 130, and may be provided adjacent to the end surface of the layer thickness regulating member 133.

As shown in an enlarged view in FIG. 9, the leveling plate 134 as a pressing member using, for example, a metal or rubber plate is used as the developing sleeve 131 (or developing sleeve 131).
(H) or the photosensitive drum 10 (or the photosensitive drum 10 a), which is disposed downstream of the layer thickness regulating member 133 in the rotation direction of the developing sleeve 131 (L) and has the flat surface of the flat carrier and has a latent image. ). Pressed by the leveling plate 134, the magnetic carrier (flat carrier)
Of the photosensitive drum 10 (or the photosensitive drum 10
The flat carrier comes out of the leveling plate 134 in a state opposite to a). In order that this flat surface does not change, the leveling plate 1
It is necessary not to provide a magnetic pole from 34 to the magnetic pole N1 forming the magnetic brush.

The developer removing plate 138 is provided so as to face the magnetic pole N2 of the magnet roll 132.
The developer on the developing sleeve 131 is peeled off by the action of the repulsive magnetic field 3 and the magnet plate 138A provided on the back surface of the removing plate 138.

The transport / supply roller 135 transports the developer peeled off by the removing plate 138 to the stirring screw 136 and supplies the developer stirred by the stirring screw 136 to the layer thickness regulating member 133. A blade 135A is provided on the transport / supply roller 135 and transports the developer.

The agitating screws 136 and 137 rotate at a constant speed in directions opposite to each other, agitate and mix the toner and the magnetic carrier in the developing device 13, and form a two-component developer containing a predetermined toner component uniformly. And

The toner supplied into the developing device housing 130 from the toner supply port opened to the top plate 130A above the developing device housing 130 above the stirring screw 137 is rotated at a constant speed in directions opposite to each other. The toners 136 and 137 are stirred and mixed with the developer contained in the developing device housing 130 to form a developer having a uniform toner concentration. Conveyance / supply roller 13 on which the developer rotates
5, a two-component developer composed of flat toner and a magnetic carrier (flat carrier) is formed by the receiving member 133A and the leveling plate 134 so as to have a predetermined layer thickness. Of the developing sleeve 131 (or the developing sleeve 131
(H) or a magnetic brush formed by a vertical magnetic field Ha that is supplied onto the outer peripheral surface of the developing sleeve 131 (L) and contacts the photosensitive drum 10 (or the photosensitive drum 10 a) at the developing position. The developer that has developed the latent image on the photosensitive drum 10 (or the photosensitive drum 10a) has a magnetic pole N
2, is stripped off by the action of the repelling magnetic field of N3 and the magnet plate 138A provided on the back surface of the removing plate 138, and is again conveyed to the stirring screw 136 by the conveying and supplying roller 135. Photoconductor drum 10 (or photoconductor drum 10a)
The upper electrostatic latent image is applied to a direct current (DC) bias E1 by an alternating current (A).
C) Reverse development is performed in a contact state by a contact developing method by applying a developing bias voltage on which the bias AC1 is superimposed.

In the contact development, the developing sleeve 131 is used.
(Or the developing sleeve 131 (H) or the developing sleeve 131 (L)) and the photosensitive drum 10 (or the photosensitive drum 10 a) have a developing gap (D _SD ) of 0.5 to 2.0 m.
It is preferable to set between m. In order to allow the tip of the magnetic brush due to the vertical magnetic field Ha to be in sliding contact with the peripheral surface of the photosensitive drum 10 (or the photosensitive drum 10a) within an appropriate range in the developing region, the developer layer regulated by the layer thickness regulating member 133 is required. preferably the thickness h (D _SD) is adjusted to 1.5～3.0D _SD, thereby or sweeping streaks occurs in the toner image, and that the fog or cause is prevented.
Developing sleeve 131 (or developing sleeve 131
(H), or the position where the developing sleeve 131 (L) is close to the photosensitive drum 10 (or the photosensitive drum 10 a), the direction of gravity is the developing sleeve 131 (or the developing sleeve 131 ( H) or a position toward the developing sleeve 131 (L)). The developing sleeve 131 (or the developing sleeve 1)
31 (H) or the developing sleeve 131 (L)) having an outer diameter of 10 to 30 mm is preferably used.
Developing sleeve 131 (or developing sleeve 131
(H) or the rotation speed and the rotation direction of the developing sleeve 131 (L) are slow to prevent scattering of toner and the like, and the moving direction at the developing position is changed to the photosensitive drum 10.
The direction is preferably opposite to the moving direction of the photosensitive drum 10a. However, from the viewpoint of the image reproducibility (developability) of the developer layer, the developing sleeve 131 (or the developing sleeve 131 ( H) or the movement direction of the developing sleeve 131 (L))
(Or the same direction as the moving direction of the photosensitive drum 10a).
The developing sleeve 131 (or the developing sleeve 131 (H) or the developing sleeve 1
31 (L)) is more preferably suppressed to 1.5 to 3.5 times the peripheral speed of the photosensitive drum 10 (or the photosensitive drum 10a). Even in the contact development, a developing bias in which an AC voltage is superimposed on a DC voltage is applied to the developing sleeve 131 (or the developing sleeve 131 (H) or the developing sleeve 131 (L)). In the reversal development, the DC component (DC component) of the bias voltage is preferably set to a voltage lower by about 100 to 200 V than the receiving potential in the non-image background portion of the photosensitive drum 10 (or the photosensitive drum 10a). The frequency as the alternating current component (AC component) 1～5KHz, amplitude V _pp 500
A range of up to 1500 V is preferably used. Also in the contact development, the development efficiency (developability) increases due to the oscillating electric field effect by applying an AC bias. In other words, the brush of the brush on the image is eliminated by loosening the aggregation of the developer and softening the magnetic brush. Furthermore,
The magnetic brush formed by the perpendicular magnetic field Ha and slidably in contact with the latent image surface prevents the image of the toner being swept toward the solid image edge portion, thereby performing high density, good development without unevenness. The contact development by the magnetic brush using the vertical magnetic field Ha by the developing means is performed in the same manner even when a spherical carrier is used.

The photosensitive drum 10 (or the photosensitive drum 1)
0a) and the developing sleeve 131 (or the developing sleeve 13).
1 (H) or a two-component developer using flat magnetic toner particles (flat carrier) and flat toner when performing contact development in the developing region between the developing sleeve 131 (L) and the developing sleeve 131 (L)). As shown in FIG. 10, the flat-shaped magnetic carrier prepared by the manufacturing method described above with reference to FIG. 6 has an easy axis of magnetization in the plane, so that the flat portions (flat surfaces) of the flat carrier are connected in a chain. A magnetic brush is formed, and flat toner charged by friction charging adheres mainly to the flat portion of the flat carrier. Vertical magnetic field H at development position
a, the tip side of the magnetic brush formed on the photosensitive drum 10 (or the photosensitive drum 10a) slidably contacts the peripheral surface of the photosensitive drum 10 (or the photosensitive drum 10a) so as to trace the photosensitive drum 10 (or the photosensitive drum 10a). Development takes place below. The flat toner particles adhering to the sliding flat carrier repeatedly reciprocate with the image forming body surface under an oscillating electric field, and when the image forming body surface retreats from the developing area, a direct current bias component (DC component) is applied. The toner particles adhere only to the limited latent image portion, and the flat toner particles temporarily adhered to other portions are swept away by the magnetic brush, so that good development is performed.

The photosensitive drum 10 (or the photosensitive drum 1)
0a) and the developing sleeve 131 (or the developing sleeve 13).
1 (H) or a two-component developer using a spherical carrier and flat toner when performing contact development in the development area between the development sleeve 131 (L)) as shown in FIG. The magnetic brush of the spherical carrier formed by the vertical magnetic field Ha is such that the adjacent magnetic brushes are in close contact with each other to form a uniform and dense developer layer. It tends to be stronger than a flat carrier. A spherical carrier has a small surface area and a small amount of adhered toner. The present inventors have conducted a comparative study using the same flat toner and using a flat carrier and a spherical carrier under optimum developing conditions for each case. Obviously superior.

Next, non-contact development using a two-component developer composed of a flat toner and a magnetic carrier (spherical carrier or flat carrier) will be described. A magnet roll 132A having a different magnetic pole arrangement at the developing position is used in place of the magnet roll 132 as the magnetic field generating means described with reference to FIGS.
Forming a magnetic brush that is not in contact with the image forming body on the developer conveying body by the horizontal magnetic field Hb formed by the magnetic pole of 32A;
Non-contact development is performed under a development bias.

FIGS. 12 to 14 and FIGS.
According to FIG. 9, the developing device 1 as a developing means shown in FIG.
3, reference numeral 130 denotes a developing device housing which is a developer accommodating portion for accommodating a two-component developer comprising flat toner and a flat carrier as a magnetic carrier; 132A, a magnet roll which is a magnetic field generating means having fixed magnetic poles;
Numeral 1 (or 131 (H) or 131 (L)) is a developing sleeve which is a developer conveying body having a magnet roll 132A therein, and 133 is a developing sleeve 131 (or developing sleeve 131 (H) or developing sleeve 131).
(L)) A layer thickness regulating member which is a layer thickness regulating means made of a magnetic material for regulating the thickness of the above developer layer to a predetermined amount, 133A is a developer receiving member made of a non-magnetic material, and 134 is a layer thickness regulating member. A leveling plate for leveling the developer whose layer thickness is regulated from 133, 138 is a developer removing plate having a magnet plate 138A on the back surface, 135 is a feeding roller, and 136 and 137 are a pair of stirring screws. is there. Reference numeral 139 denotes a toner density detection sensor that detects the toner density of the developer using, for example, a piezoelectric element.

Developing Sleeve 131 as Developer Conveyor
The developing sleeve 131 (H) or the developing sleeve 131 (L) is made of a non-magnetic cylindrical member having an outer diameter of 8 mm to 60 mm using, for example, a stainless material, and is formed of the photosensitive drum 10 (or the photosensitive drum 10 a). ) To the developing sleeve 131 (or the developing sleeve 131).
(H) or a horizontal magnetic field Hb generated by the magnetic poles N11 and S21 of the magnet roll 132A while maintaining a predetermined gap (D _SD ) by abutting rollers (not shown) provided at both ends of the developing sleeve 131 (L)). The magnetic brush on the formed developing sleeve 131 (or the developing sleeve 131 (H) or the developing sleeve 131 (L)) is brought into non-contact with the photoconductor drum 10 (or the photoconductor drum 10 a), and at the developing position. The photosensitive drum 10 is rotated in the same direction as the rotation. Non-contact development is performed in which the magnetic brush on the developing sleeve 131 (or the developing sleeve 131 (H) or the developing sleeve 131 (L)) is not in contact with the photosensitive drum 10 (or the photosensitive drum 10a).
Developing sleeve 131 (or developing sleeve 131
(H) or the peripheral surface of the developing sleeve 131 (L)) is 2
It is preferable to perform a treatment for improving the transportability of the developer as a rough surface having a thickness of 15 μm.

The magnet roll 132A is included in the developing sleeve 131 (or the developing sleeve 131 (H) or the developing sleeve 131 (L)) and includes a plurality of magnetic poles N.
11, N21, N2, N3, S1, S21, and S22 are alternately arranged, and the developing sleeve 131 (or the developing sleeve 1) is arranged.
31 (H) or the developing sleeve 131 (L)) and applies a magnetic force to the peripheral surface of the non-magnetic sleeve. The horizontal magnetic field Hb formed by the magnetic pole N11 and the magnetic pole S21 forms a magnetic brush that is not in contact with the photosensitive drum 10 (or the photosensitive drum 10a). The toner (flat toner) is caused to fly from the magnetic brush using a magnetic brush by the horizontal magnetic field Hb and a developing bias in which an AC voltage is superimposed on a DC voltage applied to the magnetic brush, and the photosensitive drum 10 (or the photosensitive drum) 10a) Develop the latent image on the photosensitive drum 10 (or the photosensitive drum 10a)
A toner image is formed thereon.

The magnetic force on the peripheral surface of the developing sleeve 131 (or the developing sleeve 131 (H) or the developing sleeve 131 (L)) is between 500 and 1200 gauss. Necessary to form.

Layer thickness regulating member 133 as layer thickness regulating means
Is opposed to the magnetic pole N3 of the magnet roll 132A, and the developing sleeve 131 (or the developing sleeve 131 (H),
Alternatively, the developing sleeve 131 (or the developing sleeve 131 (or (L))) is made of, for example, a rod-shaped or plate-shaped magnetic stainless material and is disposed at a predetermined gap from the developing sleeve 131 (L).
(H) or the layer thickness of the two-component developer on the peripheral surface of the developing sleeve 131 (L)).

The receiving member 133A is made of a non-magnetic member using a resin member such as an ABS resin, for example. The developing sleeve 131 (or the developing sleeve 131 (H) or the developing sleeve 131 (H)) is provided on the downstream side in the rotation direction of the developing sleeve 131.
(L)) and a predetermined gap, and the layer thickness regulating member 133.
Is formed integrally with, for example, a layer thickness regulating member 133 with an adhesive to prevent toner spillage from the developer layer regulated by the layer thickness regulating member 133, and a two-component developer. Is stably kept on the peripheral surface of the developing sleeve 131 (or the developing sleeve 131 (H) or the developing sleeve 131 (L)). The receiving member 133A may be formed by the developing device housing 130, and may be provided adjacent to the end surface of the layer thickness regulating member 133.

For example, a leveling plate 134 as a pressing member using a metal or rubber plate is provided to face the magnetic pole N11, and as described above with reference to FIG.
The photosensitive drum 10 (which is disposed on the downstream side of the layer thickness regulating member 133 in the rotation direction of the developing sleeve 131 (H) or the developing sleeve 131 (L)) has a flat surface of the flat carrier and has a latent image. Alternatively, it is formed facing the surface of the photosensitive drum 10a). The flat surface of the magnetic carrier (flat carrier) is pressed by the leveling plate 134 and the photosensitive drum 1
The flat carrier comes out of the leveling plate 134 in a state where the flat carrier is opposed to 0 (or the photosensitive drum 10a). In order that this flat surface does not change, the magnetic pole N11 facing the leveling plate 134 can be used.
From the magnetic pole S2 forming the magnetic brush by the horizontal magnetic field Hb
It is necessary not to provide a magnetic pole between the two.

The developer removing plate 138 is provided so as to face the magnetic pole N2 of the magnet roll 132A.
The developer on the developing sleeve 131 is peeled off by the action of the repelling magnetic field of N3 and the magnet plate 138A provided on the back surface of the removing plate 138.

The transport supply roller 135 transports the developer peeled off by the removing plate 138 to the stirring screw 136 and supplies the developer stirred by the stirring screw 136 to the layer thickness regulating member 133. A blade 135A is provided on the transport / supply roller 135 and transports the developer.

The agitating screws 136 and 137 rotate at a constant speed in directions opposite to each other, agitate and mix the toner and the magnetic carrier in the developing unit 13, and form a two-component developer containing a predetermined toner component uniformly. And

The toner supplied into the developing device housing 130 from the toner supply port opened in the top plate 130A above the developing device housing 130 above the stirring screw 137 is rotated at a constant speed in directions opposite to each other. The toners 136 and 137 are stirred and mixed with the developer contained in the developing device housing 130 to form a developer having a uniform toner concentration. Conveyance / supply roller 13 on which the developer rotates
5, a two-component developer composed of flat toner and a magnetic carrier (flat carrier) is formed by the receiving member 133A and the leveling plate 134 so as to have a predetermined layer thickness. Of the developing sleeve 131 (or the developing sleeve 131
(H) or on the outer peripheral surface of the developing sleeve 131 (L)), and a magnetic brush which is not in contact with the photosensitive drum 10 (or the photosensitive drum 10 a) is formed at the developing position by the horizontal magnetic field Hb. The developer that has developed the latent image on the photosensitive drum 10 (or the photosensitive drum 10a) has a magnetic pole N
2, is stripped off by the action of the repelling magnetic field of N3 and the magnet plate 138A provided on the back surface of the removing plate 138, and is again conveyed to the stirring screw 136 by the conveying and supplying roller 135. Photoconductor drum 10 (or photoconductor drum 10a)
The upper electrostatic latent image is applied to a direct current (DC) bias E1 by an alternating current (A).
C) The flat toner of the magnetic brush composed of the flat toner and the magnetic carrier (flat carrier) is caused to fly to the photosensitive drum 10 (or the photosensitive drum 10a) by an oscillating electric field caused by the application of the developing bias voltage on which the bias AC1 is superimposed. And reversal development in a non-contact state by a non-contact development method.

In non-contact development, the developing sleeve 13
1 (or the developing sleeve 131 (H) or the developing sleeve 131 (L)) and the photosensitive drum 10 (or the photosensitive drum 10 a) have a developing gap (D _SD ) of 300 to 100.
Preferably, it is set between 0 μm. If the gap between the developing sleeve 131 (or the developing sleeve 131 (H) or the developing sleeve 131 (L)) and the photosensitive drum 10 (or the photosensitive drum 10 a) is smaller than 300 μm and too small, the developing action is performed uniformly. It becomes difficult to form the developing layer of the non-contact magnetic brush, and it is also impossible to supply sufficient flat toner to the developing area, so that stable development cannot be performed. Conversely, the developing sleeve 131
If the gap between the photoconductor drum 10 (or the photoconductor drum 10a) and the photoconductor drum 10 (or the photoconductor drum 10a) is too large, the opposing electrode effect is reduced and sufficient development density is obtained. Can not be obtained. When the gap between the developing sleeve 131 (or the developing sleeve 131 (H) or the developing sleeve 131 (L)) and the photoconductor drum 10 (or the photoconductor drum 10 a) is set in the range of 300 to 1000 μm, an appropriate thickness The developer layer of the magnetic brush in contact can be formed uniformly. For this reason, the developing sleeve 131 (or the developing sleeve 131 (H) or the developing sleeve 131 (H)
(L)) and the photosensitive drum 10 (or the photosensitive drum 10
a) The thickness of the developer layer of the magnetic brush in the development gap (D _SD) and h a ([mu] m) to adjust the pressing member so as to be 0.5~0.8D _SD, the developer layer in the developing gap and the magnetic brush The developer layer of the magnetic brush is transferred to the photosensitive drum 10 so that no vibrating electric field is generated during non-image formation.
(Alternatively, it is preferable to set the condition so as not to come into contact with the surface of the photosensitive drum 10a and to be as close as possible. As a result, sweeping or fogging occurs in the toner image formed by the flat toner formed on the photosensitive drum 10 (or the photosensitive drum 10a) due to the rubbing of the non-contact magnetic brush formed by the horizontal magnetic field Hb. Is prevented. Developing sleeve 131 (or developing sleeve 131 (H) or developing sleeve 131 (L))
Is located in the vicinity of the photosensitive drum 10 (or the photosensitive drum 10a), the direction of gravity is the developing sleeve 131 (or the developing sleeve 131 (H),
Alternatively, a position that is directed toward the developing sleeve 131 (L) is preferable. Further, the developing sleeve 131 (or the developing sleeve 131 (H) or the developing sleeve 131)
(L)) preferably has an outer diameter of 10 to 30 mm, and the developing sleeve 131 (or the developing sleeve 131) is used.
(H) or the rotation speed and the rotation direction of the developing sleeve 131 (L) are slow to prevent scattering of toner and the like, and the moving direction at the developing position is changed to the photosensitive drum 10.
The direction is preferably opposite to the moving direction of the photosensitive drum 10a. However, from the viewpoint of image reproducibility (developability) by the developer layer, the developing sleeve 131 (or the developing sleeve 131 ( H) or the moving direction of the developing sleeve 131 (L))
0 (or the photosensitive drum 10a) is preferably the same as the moving direction of the photosensitive drum 10 (or the photosensitive drum 10a).
The developing sleeve 131 (or the developing sleeve 131 (H) or the developing sleeve 1
31 (L)) is more preferably suppressed to 1.5 to 3.5 times the peripheral speed of the photosensitive drum 10 (or the photosensitive drum 10a). The development under the oscillating electric field includes a DC voltage related to fog prevention and a development density, a development density, and a development bias applied to the development sleeve 131 (or the development sleeve 131 (H) or the development sleeve 131 (L)). It is preferable to generate an oscillating electric field in the developing region by superimposing the AC voltage on the gradation property. In the reversal development, a direct current component (DC component) of the developing bias is applied to the photoreceptor drum 10 (or the photoreceptor drum 10a) with respect to the receptive potential in the non-image background portion.
It is preferable to set the voltage to about 0 to 200 V lower.
Further, as an AC component (AC component), the frequency is 1 to 10
kHz, the amplitude V _pp in the range of 1500~3000V is preferably used. The AC component is not limited to a sine wave, but may be a rectangular wave, a triangular wave, or the like. If the frequency of the AC component is too low, the vibration pitch will appear in the development.On the other hand, if it is too high, the developer will not be able to follow the electric field vibration and the development density will decrease, resulting in a clear, high-quality image. Is reduced. The amplitude V _{pp of the} AC component is related to the frequency, but the larger the value, the more the vibration is caused to vibrate the developer layer of the magnetic brush, and the development is performed in which the flat toner separates from the flat carrier and flies. As the amplitude _{Vpp of the} component increases, fogging is likely to occur, and insulation breakdown such as a lightning strike phenomenon is likely to occur. However, if the carrier particles of the developer are insulated by a resin or the like and are further flattened, dielectric breakdown can be prevented, and generation of fog can be prevented by a DC component. The developing sleeve 131 (or the developing sleeve 131 (H) or the developing sleeve 131)
The surface of (L) may be insulated or semi-insulated with a resin or oxide film, and the surface may be provided with irregularities to improve the transportability of the developer layer of the magnetic brush. By using the above developer and developing conditions,
Clear, non-contact development with stable fog and excellent resolution is performed. The non-contact development by the magnetic brush using the horizontal magnetic field Hb by the developing means is performed in the same manner even when a spherical carrier is used.

The photosensitive drum 10 (or the photosensitive drum 1)
0a) and the developing sleeve 131 (or the developing sleeve 13).
1 (H) or a two-component developer using flat magnetic carrier particles (flat carriers) and flat toner when performing non-contact development in the developing region between the developing sleeve 131 (L) and the developing sleeve 131 (L)). As shown in FIG. 13, the flat-shaped magnetic carrier prepared by the manufacturing method described above with reference to FIG. 6 has an easy axis of magnetization in the plane, so that the developing sleeve 131 (or the developing sleeve 131 (H ) Or on the peripheral surface of the developing sleeve 131 (L)).
As a result, the flat portions (flat surfaces) of the flat carrier are connected to form a brush-shaped magnetic brush that is not in contact with the photosensitive drum 10 (or the photosensitive drum 10a), and the flat portion of the flat carrier is charged by frictional charging. Flat toner is attached. In the developing region, the horizontal magnetic field Hb causes a large number of magnetic brushes formed in an independent parallel state in a non-contact state with the photoconductor drum 10 (or the photoconductor drum 10a) to superimpose an alternating current on the above-described direct current. Due to the oscillating electric field caused by the application of the developing bias, the flat toner is released from the flat carrier located at the middle as well as the uppermost layer, flies, and adheres to the latent image portion. Therefore, when the flat carrier and the flat toner described above are used, high-density and good development without unevenness is performed.

The photosensitive drum 10 (or the photosensitive drum 1)
0a) and the developing sleeve 131 (or the developing sleeve 13).
1 (H) or non-contact development with a two-component developer using a spherical carrier and flat toner when performing non-contact development in the development area between the development sleeve 131 (L)) and FIG. As shown in FIG. 14, in the case of a spherical carrier, the magnetic brushes formed by the horizontal magnetic field Hb are in close contact with each other,
A uniform and dense velvety developer layer is formed. Therefore, even under an oscillating electric field, only the flat toner adhered to the spherical carrier located in the upper layer contributes to the development, and the flat toner adhered to the spherical carrier in the lower layer has poor developability, and the spherical carrier has a small surface area. Combined with the fact that the amount of toner is small, only low-density development is performed as compared with the case where a flat carrier is used. In order to perform development at the same density as when using the flat carrier, the peripheral speed of the developing sleeve 131 (or the developing sleeve 131 (H) or the developing sleeve 131 (L)) is increased. In such a case, adhesion of the spherical carrier to the surface of the image forming body is recognized. The inventors of the present invention have set the same conditions when using flat magnetic carrier particles (flat carriers) and spherical carriers as the carrier of the developer used for non-contact development, with the other development conditions being completely the same. As a result of comparative study, all of the development unevenness were good,
It was confirmed that the flat carrier was excellent at the above-mentioned development concentration.

Further, in order to prevent an edge effect in the toner image due to the flat toner on the photosensitive drum 10 (or the photosensitive drum 10a) in the contact development or the non-contact development, as described above with reference to FIG. Alternatively, the volume resistivity of the magnetic carrier using the flat carrier is set to 10 ⁸ to
It is preferable that the resistance is set to 10 ¹² Ω · cm, and the developing sleeve 131 (or the developing sleeve 131) is used as described above with reference to FIGS. 10, 11, 13, and 14.
(H) or the AC component (AC bias component) of the developing bias applied to the developing sleeve 131 (L), so that the flat surface of the flat toner adheres to the photosensitive drum 10 (or the photosensitive drum 10 a). Is preferred. As a result, the electric field E at the edge of the developing bias
Concentration does not occur, as shown in FIG.
The photosensitive drum 10 (or the photosensitive drum 10 at the end of the latent image area of the image formed by the electric field E of the developing bias)
a) Preventing the accumulation and rising of the flat toner of the upper toner image, and as shown in FIG. 15B, the photosensitive drum at the end of the latent image area of the image formed by the electric field E of the developing bias The flat toner on the photosensitive drum 10 (or the photosensitive drum 10a) is turned into a laid-down toner image. The edge effect at the end of the latent image area is eliminated, and the flat toner is
(Or the photosensitive drum 10a).
As a result, streaky images due to the edge effect are prevented.

By increasing the resistance of the magnetic carrier and the AC component of the developing bias, it is possible to prevent the breakdown and the flat surface of the flat toner from easily adhering to the photosensitive drum 10 (or the photosensitive drum 10a). Further, the AC component makes it possible to vibrate the flat toner on the photoconductor drum 10 (or the photoconductor drum 10a) to form a thin, uniform and stable toner layer.

The photosensitive drum 10 (or the photosensitive drum 1)
0a) In order for the flat toner to adhere uniformly and stably on the flat surface, as described above with reference to FIG. 7, the flat toner adheres on the magnetic carrier using a spherical carrier or a flat carrier in a flat surface. Is needed. The flat carrier has a larger facing area with the photosensitive drum 10 (or the photosensitive drum 10a) than the spherical carrier, and the developing efficiency is improved. Further, the specific surface area of the flat carrier is larger than that of the spherical carrier, and grounding with a high toner concentration is possible even when the same mass% is used.

As described above, the developability is improved by the development using the two-component developer composed of the flat carrier and the flat toner, and it is possible to provide an image forming apparatus with less development unevenness. In particular, with the flat carrier whose flat surface is directed to the image forming body by the pressing member, a large amount of toner (flat toner) is adhered to the image forming body, and an image forming apparatus in which generation of development unevenness is prevented can be realized. Further, the developability is improved even by contact development or non-contact development using a two-component developer composed of a flat carrier and a flat toner, and it is possible to provide an image forming apparatus with less development unevenness. In particular, the flat toner adhered to the flat carrier has no edge effect due to the magnetic carrier using a high-resistance flat carrier having a volume resistivity of 10 ⁸ to 10 ¹² Ω · cm to which the AC component of the developing bias is applied. Thus, an image forming apparatus can be formed in which a good image without development unevenness is formed by being uniformly laid on an image forming body in a laid state.

FIG. 16 is a view showing a toner image composed of flat toner on an image forming body, a transfer material or an intermediate transfer body.
The above-mentioned flat magnetic carrier particles (flat carriers)
An image is formed in each image forming apparatus by using the flat toner. In this case, especially when recording paper (paper) is used as the transfer material, the recording paper is made of fiber, and the surface has irregularities. When a general amorphous toner is used, the adhesion state of the toner tends to be disturbed when the toner image is transferred from the image forming member to the transfer material or from the intermediate transfer member to the transfer material. However, in the image forming apparatus described with reference to FIG. 1, the flat toner is used as the toner of the developer, so that the flat toner is placed on the photosensitive drum 10a as an image forming body as shown in FIG. Are adhered while maintaining the flat portion (flat surface) of the photoconductor drum, and are thinned and flattened on the photoconductor drum 10a to form a superposed color toner image without toner disturbance. Flat on 10a Color toner image with a plane attached to the thin layer superposition, Figure 16
As shown in (B), even on the transferred recording paper P, the flat toner of the flat toner is adhered to the thin layer while maintaining the flat surface, and the thinned and flattened color toner of the superposition without disturbance of the toner is obtained. An image is formed. When a toner image is formed on the photosensitive drum 10a, the flat toner can move while keeping the flat portion aside, so that the toner image is less likely to be disturbed. Further, since the flat toner lays the flat portion sideways, the potential is low, and the transfer conditions are less likely to shift.

In the tandem-type image forming apparatus described with reference to FIG. 2 or FIG. 3, by using flat toner as a developer, as shown in FIG. The flat portion (flat surface) of the flat toner is adhered while maintaining a flat portion (flat surface) of the flat toner on each photoconductor drum 10, and a thinned and flattened toner image without toner disturbance is formed on each photoconductor drum 10. And each of the photosensitive drums 1
The toner image attached to the thin layer while maintaining the flat surface on 0 is
As shown in FIG. 16C, even on the transfer belt 14a as the transferred intermediate transfer member, the flat toner of the flat toner is attached to the thin layer while maintaining the flat surface, and the thinned and flattened toner turbulence is obtained. The superimposed color toner image formed on the transfer belt 14a is attached to a thin layer with a flat surface on the transfer belt 14a.
As shown in FIG. 6 (B), even on the transferred recording paper P, the flat toner of the flat toner is adhered to the thin layer while maintaining the flat surface, and the thinned and flattened color of the superposed color without toner disturbance is obtained. A toner image is formed. When a toner image is formed on the photosensitive drum 10, the flat toner can move while keeping the flat portion aside, so that the toner image is less likely to be disturbed. Further, since the flat toner lays the flat portion sideways, the potential is low, and the transfer conditions are less likely to shift. When the toner image is transferred from the photosensitive drum 10 to the transfer belt 14a, the toner image is transferred to the transfer belt 14a having a stable volume resistivity and surface property.
Stable transfer of a toner image composed of flat toner with a flat flat surface is performed. In addition, since the flat toner has the flat portion on the side of the transfer belt 14a, the potential (toner potential)
It is low even if it overlaps. At the time of batch transfer of the superimposed color toner image from the transfer belt 14a to the recording paper P, the transfer belt 14a having little unevenness of the electric potential from the transfer belt 14a to the recording paper P of the color toner image composed of the flat toner with the flat surface laid down. , The superimposed color toner image is less likely to be disturbed.

In the above description, the flat toner of a single color adhered on the photosensitive drum 10 (or the photosensitive drum 10a) is placed on the photosensitive drum 10 (or the photosensitive drum 10a) with the flat toner lying flat. It is preferable to set the amount of covering the latent image portion of (1) uniformly as the maximum necessary amount. That is, the preferable toner layer thickness of the flat toner is (0.7 to 1.3) × d (d is FIG. 4) in a state where the flat toner is uniformly attached without any gap (a state where the flat toner is crushed). (The thickness of the flat toner described above), whereby a thin toner image having a sufficient image density can be formed.

As described above, by using the flat toner as the toner for the developer, the toner image and the superimposed color toner image can be thinned and flattened, and the flat toner can be horizontally transferred during transfer. Since the transfer (movement) is performed while maintaining the state, the toner image and the color toner image are less disturbed, and an image forming apparatus with improved transferability can be provided.

In each of the above-described image forming apparatuses,
FIGS. 17 to 21 show a method of reducing unevenness of a toner image or a color toner image, or preventing transfer unevenness due to a change in transfer conditions depending on the amount of toner adhered and toner scattering (toner scattering) at the time of transfer. This will be described with reference to FIG. FIG. 17 is a block diagram of an image forming processing system in the image forming apparatus. FIG. 18 is a diagram showing the amount of toner adhered by the UCR process. FIG. FIG. 20 is a diagram showing a pulse width modulation circuit and a dot redistribution state. FIG. 21 is a diagram showing a latent image potential formed on an image forming body by pulse width modulation. FIG. 5 is a diagram illustrating a state of attachment of flat toner to a latent image potential.

According to FIGS. 17 to 19, as described above, in each image forming apparatus, the toner used for the developer is flat toner, and the flat surface of the flat toner is the photosensitive drum 10 (or After being adhered to the photosensitive drum 10a), the transfer of the color toner image is performed while maintaining the flat surface of the flat toner, and the image processing in each image forming apparatus is performed by a solid-state image sensor such as a CCD as shown in FIG. A document image is read by image reading means using an image sensor (F1). The analog image means that has amplified the output from the CCD is A / D converted into a digital signal of 8 to 10 bits per pixel, and the shading correction and the luminance information after the shading correction are converted into 256-level density information (F2). ).

The image data obtained in the image processing (1) is
By checking the density distribution of the data and the density difference between adjacent dots, it is possible to determine whether the original image is a halftone image such as a photograph or a picture or a character image such as a character or a line drawing. (F11).

Subsequently, in image processing (2), masking, U
Color processing such as CR and color correction is performed (F3). Generally, linear masking is used as masking, or non-linear masking or masking using a look-up table is used when performing advanced color correction. In the UCR, an operation of removing the gray component from the three color components and replacing it with black (K) is performed, and a process of improving the reproducibility of the shadow portion and the character portion is performed.

Subsequently, the obtained image data is subjected to γ correction for each toner (F4), and a resolution changing process and a multi-value process using pulse width modulation (PWM) as area modulation described later are performed. After (F5), the image is output to the exposure optical system 12 (or 12a, 12 (H), 12 (L)), and the image is formed by the printer (F6).

When it is determined that the image is a character image, the developing unit 13
When the image is determined to be a halftone image, development is performed in a direction to reduce the amount of color toner used by the developing device 13.

In addition to the determination of the amount of color toner used during the development, the image processing is controlled by switching between UCR (under color removal) and gamma correction as follows. The multi-value processing will be described later.

For gamma correction, switching is set low for halftone images and high for character images according to the usage ratio of color toner.

The UCR amount of color image data for forming a color toner image is as shown in FIG.
More than 50% of reproduction of only Y, M and C colors (FIG. 18)
It is preferable to perform undercolor removal. UCR 100% for character images, 50-8 for halftone images
It is preferably set to 0%. As a result, the superposed color toner image is reduced in thickness and flattened to improve the transferability, and an image having less unevenness and having no transfer unevenness is formed. In addition, as described above, by attaching the flat surface of the flat toner on the image forming body, even when the color toner images are superimposed, toner scattering (toner scattering) is small, and a good image is formed.

As shown in FIG. 19, the adhesion amount of the flat toner (toner) on the photosensitive drum 10 (or the photosensitive drum 10a) formed by the above-described method is extremely small in the low density portion. In the concentration part, it is said that it is slightly large from a small amount,
Although the amount is large in the high concentration portion, it is formed as a thin layer. The maximum color toner layer thickness in the high density portion is Y,
A total of M, C and K is formed to have a width of about 5 to 15 μm and a thickness of about 1 to 5 μm.

According to the above method, in the image forming apparatus for superimposing a color toner image on the image forming body described with reference to FIG. 1, it is easy to perform the superposition of the toner images on the image forming body. Further, reduction of the potential of the color toner layer and prevention of color mixing are achieved. Further, in a tandem type image forming apparatus that forms a color toner image by superimposing the toner image on the image forming body described above with reference to FIG. 2 or 3 on the intermediate transfer body, Superposition becomes easier. Further, the potential of the color toner layer can be reduced.

As described above, the flat toner is used as the toner used for the developer, and the undercolor removal (UCR) is 5%.
When the content is 0% or more, thinning and flattening of the superimposed color toner images are achieved, and particularly, the thinning is achieved to improve the transferability, and there is little unevenness and no transfer unevenness. An image forming apparatus on which an image is formed becomes possible. In addition, by adhering the flat surface of the flat toner on the image forming body, even if the color toner images are superimposed, toner scattering (toner scattering) is small, and an image forming apparatus capable of forming a good image can be provided. .

According to FIG. 20 or FIG. 21, in each image forming apparatus, as described above, the toner used for the developer is flat toner, and the photosensitive drum 10 (or the photosensitive drum 10a ), A multi-value processing in each image forming apparatus is such that the resolution is changed according to the image density by distributing density information, and HIEST (Hig
light Image Enhancement
Screen Technology is used to perform density modulation by area modulation. In the density modulation based on the intensity modulation, the density modulation becomes unstable in the superposition of the toner, and the layer thickness of the toner image and the superimposed color toner image increases. Area modulation is performed by pulse width modulation (PW) using a rectangular wave described below.
M) is preferably performed.

FIG. 20A shows a pulse width modulation circuit 50B using a density distribution circuit to which HIEST is applied. When density information of image data is input to the density determination circuit 51B, the density determination circuit 51B performs the processing. The information is classified into high density information and low density information, and the high density information is directly input to the D / A converter 53B. On the other hand, the low density information is input to a D / A converter 53B via a data processing unit 52B for redistributing image information. The high-density information and the low-density information on which the image information has been redistributed are D / A-converted, compared with a reference wave by a comparison circuit 54B, and the density information is subjected to pulse width modulation processing (PWM processing). And output as a square wave.

The image information redistribution process performed by the data processing section 52B adds density data of pixels adjacent to the low density portion and redistributes the data according to the image density. The number of dots in the scanning direction is reduced. By reducing the number of dots in the main scanning direction in the highlight region and increasing the distance between the dots, the contrast of the latent image in the highlight region is improved, and stable gradation image reproduction is performed.

FIG. 20B is a conceptual diagram showing the redistribution state according to the dot density on the image forming body. For example, the image density array (25, 25, 25, 25) is represented by (35, 15). ,
35, 15) and the image density array (7, 7,
(7, 7) is redistributed to (15, 0, 15, 0) and redistributed according to the density. Note that in implementation, a stripe pattern may be recognized in the redistribution shown in the middle density part of FIG. 20B, so that the weight is changed every one sub-scan or every two sub-scans to change the staggered pattern. It is preferable to adopt the dot distribution of the child pattern.

The latent image of the image forming body formed by image exposure with the rectangular wave by the pulse width modulation (PWM) is shown in FIG.
As shown in FIG. 7, the flat toner is attached so that the bottom potential surface of the potential potential formed on the image forming body and the flat surface are arranged in parallel. Since the toner image and the color toner image are formed with the flat surface of the flat toner being horizontal, the density modulation by the area modulation described above becomes easy.

As described above, the flat toner is used as the toner for the developer, and the density is modulated by the area modulation, so that the toner image and the superimposed color toner image can be made thinner and flatter. In particular, the transfer property is improved by reducing the thickness, and an image forming apparatus capable of forming an image with less unevenness and less transfer unevenness can be provided.

[0216]

According to the first or second aspect, it is possible to provide an image forming apparatus in which the developability is improved by development using a two-component developer composed of a flat carrier and a flat toner, and development unevenness is less likely to occur. Becomes In particular, with the flat carrier whose flat surface is directed to the image forming body by the pressing member, a large amount of toner (flat toner) is adhered to the image forming body, and an image forming apparatus in which generation of development unevenness is prevented can be realized.

In particular, according to the third or fourth aspect, it is possible to provide an image forming apparatus in which the developability is improved by contact development using a two-component developer composed of a flat carrier and a flat toner and development unevenness is less likely to occur. Becomes

According to the first, fifth to seventh aspects, it is possible to provide an image forming apparatus in which the developability is improved by development using a two-component developer composed of a flat carrier and a flat toner, and development unevenness is less likely to occur. Becomes In particular, the AC component of the developing bias is applied, and the volume resistivity is set to 10 ¹⁰ to 10 ¹²
The flat toner adhered to the flat carrier by the magnetic carrier using the conductive flat carrier of Ωcm,
An image forming apparatus which has no edge effect, is adhered uniformly on an image forming body in a laid state, and can form a good image without development unevenness is possible.

According to the eighth or ninth aspect, by using flat toner as the toner used for the developer, thinning and flattening of the toner image and the superposed color toner image can be achieved, and the Since the flat toner is transferred (moved) while maintaining the horizontal state, it is possible to realize an image forming apparatus in which the toner image and the color toner image are less disturbed and transferability is improved.

According to the tenth to twelfth aspects of the present invention, a flat toner is used as a toner for a developer and an undercolor removal (UCR) is set to 50% or more, so that a thin layer in a superposed color toner image is formed. And flattening,
In particular, it is possible to provide an image forming apparatus capable of forming a thin layer to improve transferability and forming an image with less unevenness and uneven transfer. In addition, by adhering the flat surface of the flat toner on the image forming body, even if the color toner images are superimposed, toner scattering (toner scattering) is small, and an image forming apparatus capable of forming a good image can be provided. .

According to the thirteenth or fourteenth aspect, a flat toner is used as the toner used for the developer, and the density is modulated by the area modulation to reduce the thickness of the toner image or the superimposed color toner image. Flattening is achieved, especially thinning is achieved and transferability is improved,
An image forming apparatus capable of forming an image with little unevenness and no transfer unevenness can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional configuration diagram of a color image forming apparatus showing a first example of an embodiment of an image forming apparatus using flat toner or flat toner and a magnetic carrier according to the present invention.

FIG. 2 is a cross-sectional configuration diagram of a color image forming apparatus showing a second example of an embodiment of an image forming apparatus using flat toner or flat toner and a magnetic carrier according to the present invention.

FIG. 3 is a cross-sectional configuration diagram of a color image forming apparatus showing a third example of an embodiment of an image forming apparatus using flat toner or flat toner and a magnetic carrier according to the present invention.

FIG. 4 is a schematic diagram illustrating an example of a flat toner.

FIG. 5 is a sectional view of a main part showing an example of an annular type continuous wet stirring mill.

FIG. 6 is a schematic view of a flat magnetic carrier.

FIG. 7 is a schematic diagram of a two-component developer using a flat toner and a spherical carrier or a flat carrier.

FIG. 8 is a sectional configuration diagram of a contact developing type developing unit using a magnetic brush using a vertical magnetic field.

FIG. 9 is a view showing a state of movement of a flat carrier by a pressing member.

FIG. 10 shows the results of 2 when contact development is performed using a flat carrier.
FIG. 6 is a diagram illustrating a state of a magnetic brush of a component developer.

FIG. 11 shows the results obtained when performing contact development using a spherical carrier.
FIG. 6 is a diagram illustrating a state of a magnetic brush of a component developer.

FIG. 12 is a sectional configuration diagram of a non-contact developing type developing unit using a magnetic brush using a horizontal magnetic field.

FIG. 13 is a diagram illustrating a state of a magnetic brush of a two-component developer when performing non-contact development using a flat carrier.

FIG. 14 is a diagram illustrating a state of a magnetic brush of a two-component developer when performing non-contact development using a spherical carrier.

FIG. 15 is an explanatory diagram of development conditions for preventing an edge effect in a two-component developer including a flat toner and a flat carrier.

FIG. 16 is a diagram illustrating a toner image formed of flat toner on an image forming body, a transfer material, or an intermediate transfer body.

FIG. 17 is a block diagram of an image forming processing system in the image forming apparatus.

FIG. 18 is a diagram illustrating a toner adhesion amount by the UCR process.

FIG. 19 is a diagram illustrating a state of attachment of flat toner on an image forming body according to an image density.

FIG. 20 is a diagram showing a pulse width modulation circuit and a dot redistribution state.

FIG. 21 is a diagram illustrating a latent image potential formed on an image forming body by pulse width modulation, and a state in which flat toner adheres to the latent image potential.

[Explanation of symbols]

 10, 10a Photoreceptor drum 11, 11 (H), 11 (L) Scorotron charger 12, 12 (H), 12 (L), 12a Exposure optical system 13, 13 (H), 13 (L) Developer 14A Conveying belt 14a Transfer belt 14C Transfer device 14c Primary transfer roller 14g Secondary transfer device 15 Paper cassette 16 Timing roller 17 Fixing device 17a Fixing roller 17b Pressure roller 100 Process unit 131, 131 (H), 131 (L) Development Sleeve 132, 132A Magnet roll 133 Layer thickness regulating member 134 Leveling plate Ha Vertical magnetic field Hb Horizontal magnetic field P Recording paper

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 15/06 101 G03G 15/08 504A 2H200 15/08 504 15/16 507 9/08 361 15/16 15 / 08 507L F-term (reference) 2H005 AA15 AA21 BA15 EA01 2H030 AB02 AD01 AD11 BB02 BB12 BB23 BB41 BB42 BB63 2H031 AB02 AC08 AC19 AC33 AC34 AD01 AD13 AE01 BA05 BA09 BB01 BC01 CA11 FA01 2H073 BA04 AB04 AB04 AC16 AD06 AD13 AD16 AD17 AD23 AD31 AD36 CA00 DA10 DA42 DA74 EA03 GA13 2H200 GA12 GA16 GA23 GA33 GA45 GA47 GA50 GA51 GA53 GA56 GA57 GA59 GB12 GB25 HA02 HA12 HB03 HB12 HB22 HB26 HB28 JA02 JB07 JB26 JBJ JC42 JB42 JBC JB42 JBC KA03 KA07 MA03 MA04 MA20 MB04 MB05

Claims (14)

[Claims] 1. An image forming apparatus comprising: an image forming body; and developing means for developing a latent image on the image forming body using a magnetic brush made of a two-component developer, wherein the developing means includes a layer of the magnetic brush. Providing a layer thickness regulating means for regulating the thickness, forming the two-component developer with a magnetic carrier and flat toner, forming the magnetic brush with a two-component developer consisting of the magnetic carrier and flat toner, An image forming apparatus, wherein a toner image is formed by attaching a flat surface of the flat toner to a latent image on an image forming body. 2. A flat carrier is used as the magnetic carrier, and pressing means is provided downstream of the layer thickness regulating means in the moving direction of the two-component developer, and the pressing means causes the flat carrier to have a flat surface. 2. The image forming apparatus according to claim 1, wherein the image forming apparatus is formed so as to face a surface of the image forming body having the latent image. 3. The image forming apparatus according to claim 2, wherein a flat surface of the flat carrier is attached to the image forming body. 4. The image forming apparatus according to claim 2, wherein a magnetic pole for forming the magnetic brush is not provided between the pressing unit and a developing position of the developing unit. 5. The magnetic carrier has a volume resistivity of 10 ^8.
To 10 ¹² Ω · cm and the developing means
A developer transporter for transporting a component developer is provided, and a flat surface of the flat toner is attached to the image forming body by an AC component of a developing bias applied to the developer transporter. 2. The image forming apparatus according to 1. 6. The image forming apparatus according to claim 5, wherein a flat carrier is used as the magnetic carrier. 7. The image forming apparatus according to claim 6, wherein a flat surface of the flat toner is attached to the flat carrier. 8. A toner image formed by a plurality of toner image forming means is sequentially transferred onto an intermediate transfer member to form a superimposed color toner image on the intermediate transfer member. In the image forming apparatus in which the color toner image is collectively transferred onto the transfer material and then the fixing device fixes the color toner image on the transfer material, the toner is a flat toner, and the flat surface of the flat toner is An image forming apparatus, wherein the color toner image is superimposed on the intermediate transfer body while maintaining the flat surface by adhering to an image forming body. 9. A toner image formed by a plurality of toner image forming means by developing with a developer containing toner.
The color toner images on the intermediate transfer member are sequentially transferred onto the intermediate transfer member to form a superimposed color toner image on the intermediate transfer member, and the color toner images on the intermediate transfer member are collectively transferred onto a transfer material. An image forming apparatus for fixing a color toner image on the transfer material, wherein the toner is a flat toner, and a flat surface of the flat toner is attached to the intermediate transfer body;
An image forming apparatus, wherein a superposed color toner image is formed on the transfer material while maintaining the flat surface. 10. An image forming apparatus for forming a toner image on an image forming body using a developer containing a toner and forming a superposed color toner image, wherein the toner is a flat toner, After attaching the flat surface to the image forming body, the color toner image is transferred while maintaining the flat surface, and the undercolor removal of 50% or more of the color image data for forming the color toner image is performed. An image forming apparatus, comprising: 11. The image forming apparatus according to claim 10, wherein a color toner image is superimposed on the image forming body. 12. The image forming apparatus according to claim 10, wherein a color toner image is formed by superimposing the toner image on the image forming member on an intermediate transfer member. 13. An image forming apparatus for forming a toner image on an image forming body using a developer containing a toner, wherein the toner is a flat toner, and an area modulation of image data for forming the toner image is performed. And forming a latent image by image exposure on the image forming body, and causing the flat surface of the flat toner to adhere to the image forming body. 14. The image forming apparatus according to claim 13, wherein pulse modulation is used for the area modulation.