JP2002258703A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device having a cleaner that has improved capability to clear away transfer residual toner on an image forming body after an image is formed by the image forming device using flat toner. SOLUTION: In the image forming device, a cleaning means has a blade member and a turning roller. The leading end of the blade member is disposed toward the turning roller, which is located upstream in the direction of the movement of the image forming body.

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 cleaning device used for forming an image such as a copying machine, a printer, a facsimile, etc. Related to the device.

[0002]

2. Description of the Related Art A conventional color image forming apparatus forms an image by forming a toner image on an image forming body, transferring and fixing the toner image on a transfer material, and cleaning the transfer residual toner on the image forming body. After the toner image is superimposed on the apparatus and the image forming body, and the superimposed color toner image is formed on the image forming body, the color toner image on the transfer material is collectively transferred.
An image forming apparatus that fixes and removes residual toner on the image forming body, or sequentially transfers the toner image formed on the image forming body to the intermediate transfer body using a toner whose color is changed for each image forming unit. After forming a superimposed color toner image on the intermediate transfer body, the color toner image on the intermediate transfer body is collectively transferred and fixed to a transfer material, and an image for cleaning the transfer residual toner on the image forming body is removed. A toner having a spherical or irregular shape produced by an ordinary pulverization method or polymerization method has been used as a toner of a developer for forming a toner image of such an image forming apparatus. The inventors of the present application have proposed an image forming apparatus using flat toner as a developer toner to improve image quality during image formation in Japanese Patent Application No. 2001-23264.

[0003]

However, in the image forming apparatus and the like using the flat toner proposed above, the toner image is thinned and flattened, and high quality image formation is achieved. The flat toner adheres flatly and closely to the image forming body, causing a problem that the cleaning property of the transfer residual toner on the image forming body after image formation is poor.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems and provides an image forming apparatus using a flat toner, which has a cleaning device for improving the cleaning property of the transfer residual toner on the image forming body after image formation. The purpose is to provide.

[0005]

An object of the present invention is to form an electrostatic latent image on an image forming body, develop the electrostatic latent image with a developer using flat toner, and form a toner on the image forming body. After forming the image, the image forming apparatus transfers the toner image onto a transfer material, and cleans the transfer residual toner on the image forming body by a cleaning unit. In the image forming apparatus, the cleaning unit includes a blade member and a rotating roller. This is achieved by an image forming apparatus, wherein the tip of the blade member is arranged toward the rotating roller provided on the upstream side in the moving direction of the image forming body.

[0006]

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 and each fixing device in the embodiments, members having the same functions and structures are denoted by the same reference numerals or symbols.

First, examples of an image forming apparatus using flat toner as a developer will be described with reference to FIGS. FIG. 1 is a cross-sectional view of a color image forming apparatus showing a first example of an embodiment of an image forming apparatus using flat toner according to the present invention, and FIG. 2 is an image forming apparatus using flat toner according to the present invention. FIG. 3 is a sectional configuration diagram of a color image forming apparatus showing a second example of the embodiment of the apparatus, and FIG.
FIG. 4 is a cross-sectional configuration view of a color image forming apparatus showing a third example of an embodiment of an image forming apparatus using flat toner according to the present invention. FIG. FIG. 4 is a diagram illustrating a toner image.

According to FIG. 1 or FIG. 4, as shown in FIG. 1, a photosensitive drum 10a as an image forming body has a cylindrical shape formed of a light-transmitting member such as glass or light-transmitting acrylic resin. A light-transmitting conductive layer and a photoconductor layer of an organic photosensitive layer (OPC) are formed on the outer periphery of the substrate.

The photosensitive drum 10a is rotated clockwise by the power from a driving source (not shown) in a state where the light-transmitting conductive layer is grounded, as shown by the arrow in FIG.

In the present invention, the exposure beam for exposing an image 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 serving as a charging means described below, an exposure optical system 12a serving as an image writing means,
Developing devices 13 as developing means respectively include yellow (Y), magenta (M), cyan (C), and black (K).
It is prepared for the image forming process for each color of
In the present embodiment, the photosensitive drums 10a are arranged in the order of Y, M, C, and K with respect to the rotation direction of the photosensitive drum 10a indicated by an arrow in FIG. A photoreceptor cleaning device 19, which is a means for cleaning the image forming body, is provided upstream of the scorotron charger 11.
Is arranged.

The scorotron charger 11 is mounted so as to face and be close to the photosensitive drum 10a in a direction perpendicular to the moving direction of the photosensitive drum 10a as an image forming body (perpendicular direction in FIG. 1). 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 attached to a cylindrical holder 20 as an exposure optical system holding member, and is accommodated in the base of the photosensitive drum 10a. Other exposure elements include FL (phosphor emission), E
A linear element in which a plurality of light emitting elements such as L (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 contains a two-component (or one-component) developer of yellow (Y), magenta (M), cyan (C) or black (K) (a flat toner, which will be described in detail later). And a developing roller 13a which is a developer carrier formed of, for example, a cylindrical non-magnetic stainless steel or aluminum material having a thickness of 0.5 to 1 mm and an outer diameter of 15 to 25 mm, respectively. I have.

In the developing area, the developing roller 13a is kept in non-contact with the photosensitive drum 10a by abutting rollers (not shown) with a predetermined gap, for example, 100 to 1000 μm, between the developing roller 13a and the rotating direction of the photosensitive drum 10a. At the closest position, it rotates in the forward direction, and at the time of development, a DC voltage of the same polarity as the toner (in the present embodiment, a negative polarity) or a DC voltage is superimposed on the DC voltage with respect to the developing roller 13a. By applying the developing bias voltage, non-contact reversal development is performed on the exposed portion of the photosensitive drum 10a. At this time, the accuracy of the development interval needs to be about 20 μm or less in order to prevent image unevenness.

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 photoconductor cleaning device 19, which is a means for cleaning the image forming body, includes a cleaning roller 191 provided on the upstream side in the rotation direction of the photoconductor drum 10a;
A cleaning blade 192 downstream of the cleaning roller 191 cleans the transfer residual toner on the photosensitive drum 10a as described later in detail.

At the start of image formation, the photosensitive drum 10a is rotated clockwise as indicated by the arrow in FIG. 1 by starting an unillustrated image forming body driving motor, 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 photosensitive drum 10a is placed on the M (scorotron) charger 1 on the yellow (Y) toner image.
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, the recording paper P, which is a transfer material, is sent out from a paper feed cassette 15 serving as a transfer material storage means by a feed roller (no code), and is fed by a feed roller (no code) to be transferred. The sheet is conveyed to a timing roller 16 as a 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 serving as a transfer material charging means. 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 contacted and conveyed by the conveyance belt 14A is transferred around the photosensitive drum 10a by a transfer unit 14C which is a transfer unit to which a voltage having a polarity opposite to that of the toner (positive polarity in this 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 discharged by a paper separation AC discharger 14h, which is a transfer material separation 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, which is a fixing roller member for fixing a superposed color toner image made of flat toner, and a pressing roller, which is a pressing roller member provided to face the fixing roller 17a. Halogen lamp HLa, which is a heating means having a heating filament (no symbol) as a heat source, is provided in the center of fixing roller 17a.

The recording paper P is sandwiched by a nip portion N formed between the fixing roller 17a and the pressure roller 17b, and a superimposed color made 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 transfer residual toner remaining on the peripheral surface of the photoconductive drum 10a after the transfer is cleaned by a cleaning roller 191 and a cleaning blade 192 provided in a photoconductor cleaning device 19 which is a means for cleaning the image forming body. You. The photoreceptor drum 10a from which the transfer residual toner has been removed is uniformly charged by the scorotron charger 11, and enters the next image forming cycle.

As described above, by using the flat toner, as shown in FIG.
4A, a thin layer and a flattened layer are formed, and a superposed color toner image without toner disturbance is formed.
As shown in (B), even on the recording paper P to which the superimposed color toner image on the photosensitive drum 10a has been transferred, the recording paper P is brought into close contact with the recording paper P, and is thinned and flattened. And a superposed color toner image is formed.

In the above description, the flat toner of a single color adhered on the photosensitive drum 10a has such an amount as to uniformly cover the latent image portion of the photosensitive drum 10a with the flat surface of the flat toner laid down. It is preferred to have the maximum required amount. That is, the preferable toner layer thickness of the flat toner is (0.7 to 1.3) × d (d is a value in FIG. 5) in a state where the flat toner is uniformly attached without any gap (a state where the flat toner is crushed).
(Thickness of a flat toner described later), whereby a thin toner image having a sufficient image density can be formed.

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 or FIG. 4, as shown in the sectional view of FIG. 2, a document table made of a transparent glass plate or the like, and a document placed on the document table There is a document placing portion 111 made up of a document cover or the like covering D. Below the document platen, in the apparatus main body, there are a first mirror unit 112, a second mirror unit 113, a main lens 120, a color CCD 123, and the like. An image reading unit A 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 a second mirror 116 and a third mirror 117, and linearly moves in the same direction on the left and right at half the speed of the first mirror unit 112 so as to always maintain a predetermined optical path length. 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
5, an image is formed on the color CCD 123 via the second mirror 116 and 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. The peripheral portion of a transfer belt 14a, which is an intermediate transfer member, is black (K). , Cyan (C), magenta (M), and yellow (Y) are provided in that order from the upstream side in the rotation direction of the transfer belt 14a. In the unit 100, K, C, M, and Y toner images using flat toner described in detail later are formed.
The superposed color toner image is transferred onto the recording paper P, which is a transfer material, is fixed, and is discharged outside the apparatus.

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

The photoreceptor drum 10 as an image forming body is formed by forming a photoconductive layer of a conductive layer and an organic photosensitive layer (OPC) on the outer periphery of a cylindrical base.

The photosensitive drum 10 is rotated in a counterclockwise direction indicated by an arrow with the conductive layer grounded by the power of a driving 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 orthogonal to the moving direction of the photosensitive drum 10 so as to face and be close to the photosensitive drum 10, and is provided with corona discharge having the same polarity as the toner. Photoconductor drum 10
To give a uniform potential.

Reference numeral 12 denotes an exposure optical system which is image writing means for performing K, C, M, and Y image exposure based on image data.
For example, it is a scanning optical system that performs scanning in parallel with the rotation axis of the photosensitive drum 10 using a polygon mirror or the like. A latent image is formed by performing image exposure on the uniformly charged photoconductor drum 10 by the exposure optical system 12.

At the periphery of the photosensitive drum 10, there is provided a developing unit 13 which is a developing means containing a two-component developer composed of a negatively charged conductive toner and a magnetic carrier. Reversal development is performed by a developing roller 13a as a developer carrier that rotates while holding the developer.

The developer is a mixture of a carrier having a ferrite core as a core and an insulating resin coated around the core, and a flat toner, which will be described in detail later.
The layer 3a is conveyed to the developing zone while being regulated to a layer thickness of 0.1 to 0.6 mm.

The gap between the developing roller 13a and the photosensitive drum 10 in the developing area is larger than the layer thickness of the developer by 0.2.
As 1.0 mm, applies an AC bias voltage obtained by superposing an AC voltage V _AC to a DC voltage V _DC between the developing roller 13a and the photosensitive drum 10. Since charging of the toner is a DC voltage V _DC of the same polarity (negative), flat toner given the opportunity to leave from the carrier by the AC voltage V _AC, the high V _H absolute value of the potential from the DC voltage V _DC The toner does not adhere to the portion, and 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 toner is visualized (a toner image composed of flat toner by reverse development is formed). A DC voltage V _DC is applied between the developing roller 13a and the photosensitive drum 10.
You may apply only. 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 belt 14a, in which four color process units 100 composed 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, which is a roller member as a first transfer unit for each color, is connected to 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 elimination means 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.

A photoconductor cleaning device 19, which is a means for cleaning the image forming body for each color, includes a cleaning roller 19 provided on the upstream side in the rotation direction of the photoconductor drum 10.
1 and a cleaning blade 192 on the downstream side of the cleaning roller 191. As will be described in detail later, the transfer residual toner on the photosensitive drum 10 is cleaned.

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

Next, the transfer belt 14a is synchronized with the M toner image and the process unit 1 of magenta (M)
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 transfer residual toner remaining on the peripheral surface of the photosensitive drum 10 for each color after the transfer is transferred to a cleaning roller 191 and a cleaning blade 192 provided in a photosensitive member cleaning device 19 which is a cleaning means for an image forming body. Cleaning.

In synchronization with the formation of the superposed color toner images on the transfer belt 14a, the recording paper as the transfer material is transferred from the paper feed cassette 15 as the transfer material storage means via the timing roller 16 as the transfer material feed means. P is conveyed to a transfer area (no symbol) of a secondary transfer device 14g, which is a second transfer unit, and is transferred onto the transfer belt 14a by a secondary transfer device 14g to which a DC voltage having a polarity opposite to that of the toner is applied. A superimposed color toner image made of flat toner is collectively transferred onto the recording paper P. 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 superimposed 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 for fixing a superposed color toner image made of flat toner, and a pressing roller as a pressing roller member provided opposite to the fixing roller 17a. Halogen lamp HLa, which is a heating means having a heating filament (no symbol) as a heat source, is provided in the center of fixing roller 17a.

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 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 which is an intermediate transfer member cleaning means provided opposite the driven roller 14e with the transfer belt 14a interposed therebetween. Will be cleaned.

As described above, by using the flat toner, as shown in FIG.
The toner image is formed on the photosensitive drum 10 of each color as shown in FIG. 4 (C). Also on the belt 14a, the color toner image is thinned and flattened in close contact with the transfer belt 14a to form a superposed color toner image without toner disturbance, and as shown in FIG. Even on the recording paper P to which the superimposed color toner image is transferred on the recording paper P, the superimposed color toner image is formed in close contact with the recording paper P, and is thinned and flattened, and the superimposed color toner image without toner disturbance is formed. .

In the above description, the flat toner of a single color adhered on the photosensitive drum 10 has such an amount as to uniformly cover the latent image portion of the photosensitive drum 10 with the flat surface of the flat toner lying down. It is preferred to have the maximum required amount.
That is, the preferable toner layer thickness of the flat toner is (0.7 to 1.3) × d (d is a value in FIG. 5) in a state where the flat toner is uniformly attached without any gap (a state where the flat toner is crushed). (Thickness of a flat toner described later), whereby a thin toner image having a sufficient image density can be formed.

According to FIG. 3 or FIG. 4, the color image forming apparatus shown in FIG. 3 is a tandem type color image forming apparatus using an intermediate transfer member, and is provided at a peripheral portion of a transfer belt 14a as an intermediate transfer member. Are black (K), cyan (C), and magenta (M) from the upstream side in the rotation direction of the transfer belt 14a.
And a process unit 100, which is an image forming process unit for forming a color image, comprising four sets of color toners including yellow, yellow, and yellow (Y). A superposed toner image of flat toner of K, C, M, and Y is formed using the dark toner of flat toner, and the toner image of flat toner formed in each process unit 100 is a transfer belt. The toner image is transferred onto the transfer belt 14a in a superimposed manner to form a superimposed color toner image made of flat toner on the transfer belt 14a.
The superimposed color toner image composed of the flat toner transferred above is collectively transferred onto the transfer material, fixed, and discharged outside the apparatus.

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.
0, a photoconductor cleaning device 19, which is a means for cleaning the image forming body for cleaning the transfer residual toner on the photoconductor drum 10, and a scorotron for a light toner for forming a light toner image. Charger 1
1 (L), an exposure optical system 12 (L) for light toner, a developing device 13 (L) for light toner composed of flat toner, and a scorotron charger 11 (for dark toner) for forming a dark toner image. H), an exposure optical system 12 (H) for dark toner, and a developing device 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 device 13 (L), which is a developing means (first developing means) for light toner made of flat toner, contains a light toner developer made of flat toner, and contacts or non-contacts the first developer. Perform reversal development. The developing device 13 (H), which is a developing means for dark toner composed of flat toner, incorporates a dark toner developer composed of flat toner and performs the second reversal development by 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
A first image exposure using light toner image data is performed by the exposure optical system 12 (L) to form a light toner latent image, and the light toner developing device 1 made of flat toner is formed.
The first development is performed by the 3 (L) developing roller 13 a (L) in a state of contact or non-contact with light toner composed of flat toner. Next, the photosensitive drum 10 on which the light toner image composed of the flat toner is formed is charged most by the scorotron charger 11 (H) for the dark toner, and the second image exposure using the image data for the dark toner is performed. Is performed by the exposure optical system 12 (H) to form a latent image of dark toner, and a developing device 13 for dark toner composed of flat toner is formed.
By the developing roller 13a (H) of (H), the second development is performed in a non-contact state by the dark toner composed of the flat toner, and the flat toner is formed on the toner image formed by the light toner composed of the flat toner. A toner image of the dark toner is formed on the photosensitive drum 10 in an overlapping manner. 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, which is 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 ¹⁰ to 10 ¹⁵ Ω / □ endless belt, for example, modified polyimide, thermosetting polyimide, ethylene tetrafluoroethylene copolymer, polyvinylidene fluoride,
An outer surface of a semiconductive film substrate having a thickness of 0.1 to 1.0 mm in which a conductive material is dispersed in an engineering plastic such as nylon alloy is coated with a fluorine coating having a thickness of 5 to 50 μm, preferably as a toner filming preventing layer. Further, it is a seamless belt having a two-layer structure. In addition to the above, the transfer belt 14a has a thickness of 0.5 to 0.5 in which a conductive material is dispersed in silicon rubber or urethane rubber or the like.
A 2.0 mm semiconductive rubber belt can also be used. The transfer belt 14a is stretched around a drive roller 14d, a driven roller 14e, a tension roller 14k, and a backup roller 14j. During image formation, the drive roller 14d is rotated by a drive motor (not shown). At the transfer position for each color, the primary transfer roller 14c
As a result, the transfer belt 14a is pressed against the photosensitive drum 10, and the transfer belt 14a is rotated in the direction indicated by the arrow in the figure.

The primary transfer rollers 14c, which are the first transfer means of K, C, M and Y, are provided to face the respective photosensitive drums 10 with the transfer belt 14a interposed therebetween. Each transfer area (no symbol) is formed between the transfer area and the photosensitive drum 10. Each primary transfer roller 14c
A DC voltage having a polarity opposite to that of the toner (positive polarity in the present embodiment) is applied to the photosensitive drum 10 for K, C, M, and Y by forming a transfer electric field in a transfer area (no sign). Are transferred on 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 photoreceptor cleaning device 19, which is a means for cleaning the image forming body, includes a cleaning roller 191 provided on the upstream side in the rotation direction of the photoreceptor drum 10 and a cleaning blade 192 on the downstream side of the cleaning roller 191. As described in detail later, the transfer residual toner on the photosensitive drum 10 is cleaned.

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 the K photosensitive drum 10 is applied with a potential, the exposure optical system 12 (L) for the K light toner performs an electrical operation 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 light toner is subjected to first reversal development in a contact or non-contact state by a developing unit 13 (L) for light toner composed of K flat toner, and the K photosensitive drum 10 The toner image is formed by the light toner composed of the flat toner of K according to the rotation of. Subsequently, it corresponds to the charging by the scorotron charger 11 (H) for the K dark toner and the image data for the K dark toner of the first color signal by the exposure optical system 12 (H) for the K dark toner. The formation of an electrostatic latent image for dark toner corresponding to the K image by the second image exposure in the external exposure by an electric signal, and the developing unit 13 (H) for dark toner composed of K flat toner By the second development in the non-contact state, the toner image of the dark toner composed of the K flat toner is formed on the previously formed light toner image of the light toner composed of the K flat toner.

The K toner image formed of the light and dark toners using the flat toner, respectively (the superposed toner formed of the flat toner) formed on the K photoreceptor drum 10 as the image forming body by the above-described image forming process. 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 10a.
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) by the third color signal. 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.

The untransferred toner remaining on the peripheral surface of the photosensitive drum 10 for each color after the transfer is transferred to a cleaning roller 191 and a cleaning blade 192 provided in a photosensitive member cleaning device 19 which is a means for cleaning the image forming body. Cleaning.

In synchronization with the formation of the superposed color toner images on the transfer belt 14a, the recording paper as the transfer material is transferred from the paper feed cassette 15 as the transfer material storage means via the timing roller 16 as the transfer material feed means. P is conveyed to a transfer area (no symbol) of a secondary transfer device 14g, which is a second transfer unit, and is transferred onto the transfer belt 14a by a secondary transfer device 14g to which a DC voltage having a polarity opposite to that of the toner is applied. The superposed color toner images made of flat toner 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 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 which is a fixing roller member for fixing a superposed color toner image made of flat toner, and a pressure roller which is a pressure roller member provided to face the fixing roller 17a. Halogen lamp HLa, which is a heating means having a heating filament (no symbol) as a heat source, is provided in the center of fixing roller 17a.

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. After the toner image is fixed, the toner image is sent by a discharge roller 18 and discharged to a tray at the top of the apparatus.

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 which is an intermediate transfer member cleaning means provided opposite to the driven roller 14e across the transfer belt 14a. Will be cleaned.

As described above, by using the flat toner, as shown in FIG.
The toner image is formed on the photosensitive drum 10 of each color as shown in FIG. 4 (C). Also on the belt 14a, the color toner image is thinned and flattened in close contact with the transfer belt 14a to form a superposed color toner image without toner disturbance, and as shown in FIG. Even on the recording paper P on which the superimposed color toner image is transferred on the recording paper P, the superimposed color toner image is formed in close contact with the recording paper P, is thinned and flattened, and has no toner disturbance. .

In the above description, the flat toner of a single color adhered on the photosensitive drum 10 has such an amount as to uniformly cover the latent image portion of the photosensitive drum 10 with the flat surface of the flat toner laid down. It is preferred to have the maximum required amount.
That is, the preferable toner layer thickness of the flat toner is (0.7 to 1.3) × d (d is a value in FIG. 5) in a state where the flat toner is uniformly attached without any gap (a state where the flat toner is crushed). (Thickness of a flat toner described later), whereby a thin toner image having a sufficient image density can be formed.

Next, the flat toner used for forming a toner image in each of the above-described image forming apparatuses will be described with reference to FIG. 5 or FIG. 6 and FIG. FIG. 5 is a schematic diagram illustrating an example of the flat toner, and FIG. 6 is a cross-sectional view of a main part illustrating an example of an annular-type continuous wet stirring mill.

According to FIG. 5 or FIG. 4 described above, the flat toner (flat particles) used in the 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 (r ₁ ) of the average length of the flat toner
And the short side (r ₂ ) 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 (r ₂ / r ₁ ) of the average length is preferably 0.6 to 1.0, and 0.8 to 1.0.
1.0 is more preferred. The ratio of the average thickness to the average short side length (d / r ₂ ) of the toner is preferably 0.1 to 0.5, and more preferably 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 (r ₁ , r ₂ ) of the flat toner is 5 μm.
If it is less than m, there is a risk of suffering from diseases such as pneumoconiosis, which is not preferable in terms of safety and hygiene. If it exceeds 20 μm, developability is reduced, and faithful development cannot be performed, and the resolution is undesirably reduced.

The ratio of the long side to the short side of the average length of the flat toner (r
_{When the} ratio ( ₂ / r ₁ ) is less than 0.8, especially less than 0.6, the flat portion of the flat toner hardly adheres onto the image forming body, the toner layer becomes thicker, the toner consumption increases, and the transfer occurs. In addition, toner scattering and toner spread in the fixing process increase, which is not preferable.

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. Is difficult to develop in a layered form, and the toner layer becomes thicker, and the amount of consumed toner is increased.

If the ratio of the average thickness to the average short side length (d / r ₂ ) 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. It is not preferable because it causes scattering and fogging. If it is more than 0.4, especially more than 0.5, the flat portion of the toner hardly adheres to the image forming body, the toner layer is hardly developed in a layer, and the toner layer becomes thick. This 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.

By forming the flat toner into the above-described shape, as described above with reference to FIG. 4, when development is performed using the flat toner and a toner image is formed on an image forming body (photosensitive drum), The flat toner on the formed body is attached in a more layered manner with the flat portion of the flat toner facing the image forming body. 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), the recording paper is composed of fibers,
Furthermore, since the surface has irregularities, the surface and the inside are electrically non-uniform, and the electrical characteristics change greatly due to humidity. Therefore, the image is transferred from the image forming body to the transfer material (recording paper) or from the intermediate transfer body At the time of transfer to a material (recording paper), the flat toner adhesion state tends to be disordered.

The surface charge state of the flat toner is substantially uniformly charged, and therefore, 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.

The 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 the toner scattering and the spread of the toner image in the transfer and fixing processes 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) each 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 not produced by a pulverization method or 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 in the image forming apparatus of the present invention is prepared by suspending / 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 to produce secondary particles. Then, an organic solvent, a coagulant, a polymerization catalyst and the like are added to carry out polymerization, and the polymerization rate becomes 8
The spherical secondary particles (spherical toner) in the solution advanced to 0% are circulated through a pressurized bottleneck while being heated together with the solution to flatten the particle shape, and a polymerization catalyst is added to polymerize. To complete the process.

[0110] Salting out / fusion refers to salting out fine resin particles produced in the polymerization step using a coagulant, removing excess dispersing agent, surfactant and the like, and simultaneously reducing the size of the resin particles by heat fusion. 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 liquid such as a release agent or a colorant necessary for forming the toner, or by using a toner composition such as a release agent or a colorant in a 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, an ultrasonic dispersion 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 completion of the polymerization, the dispersion stabilizer is removed, filtered, washed, and dried to obtain the flat toner used in the image forming apparatus of the present invention.

As shown in FIG. 6, 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 the 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 dissociating 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 the 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, if necessary. You can also. 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, dye, pigment and the like can be arbitrarily used.

As the 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 for adding a colorant, a method in which a colorant is added at the stage of polymerizing a monomer and polymerized to form 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 control 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 particles formed by salting out / fusing can be carried out 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 image forming apparatus of the present invention, more effects can be exhibited 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 to be 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.

In each of the above-described image forming apparatuses, by using the flat toner as described above, a high-density image can be obtained even if the toner consumption is small, and the image has little unevenness.
In addition, it is possible to obtain a print-like high-quality image without toner scattering.

However, in the above-described image forming apparatus using the flat toner, although the toner image is thinned and flattened to form a high-quality image, the flat toner remains flat on the image forming body. This causes a problem that the cleaning ability of the transfer residual toner on the image forming body after image formation is poor.

A cleaning device which solves this problem and improves the cleaning performance of the transfer residual toner on the image forming body after image formation will be described with reference to FIGS. 7 to 9 and FIG. FIG. 7 is a partially enlarged explanatory view of a cleaning device that cleans flat toner on an image forming body by using a rotating roller that applies a first cleaning bias and a blade member, and FIG. 8 is a surface state of the rotating roller. FIG. 9 is a partially enlarged explanatory view of a cleaning device that performs cleaning of flat toner by applying a second cleaning bias to the blade member of FIG. 7.

According to FIGS. 7 to 9, as shown in FIG. 7, the photosensitive member cleaning device 19, which is a means for cleaning the image forming member, includes a rotating roller provided on the upstream side in the rotation direction of the photosensitive drum 10a. Cleaning roller 1
91, and a cleaning blade 192 which is a blade member disposed at the downstream side of the cleaning roller 191 with its tip directed toward the cleaning roller 191. The cleaning roller 191 and the cleaning blade 192 form the photosensitive drum 10a. At this time, preferably, the cleaning roller 191 is forcibly driven, and the cleaning roller 191 has a polarity opposite to that of the toner (positive polarity in this embodiment), for example, +200 to +50.
A first cleaning bias VC1 consisting of a DC voltage of about 0 V is applied to attract the flat toner remaining after transfer of the negative polarity on the photosensitive drum 10 (or the photosensitive drum 10a). Then, cleaning is performed by causing the flat toner remaining after transfer to adhere to the cleaning roller 191. The forced driving of the cleaning roller 191 also has the effect of scraping flat toner remaining after transfer. The transfer residual flat toner adhered to the cleaning roller 191 is scraped off by the scraping plate 191a and stored in the photoconductor cleaning device 19. The transfer residual flat toner that has not been cleaned by the cleaning roller 191 is also cleaned by the cleaning blade 192.

The cleaning roller 191 has an outer diameter φ1.
(Mm) is about 8 to 20 mm, and is formed so as to have irregularities on the surface by using a sponge roller made of a foam such as a silicone resin or a urethane resin. However, as described above with reference to FIG. Has a volume average particle size of 3 to 10 μm
m, more preferably 4 to 9 μm, preferably a flat toner having a long side (r ₁ ) and a short side (r ₂ ) of 5 to 20 μm in average length and _{1 to 5} μm in average thickness (d). On the other hand, as shown in FIG. 8, the width W (μm) of the unevenness on the surface of the cleaning roller 191 is about 2 to 10 times the long side (r ₁ ) of the average length of the flat toner, and the depth of the unevenness on the surface is D (μ
m) is about 1 to 5 times the average thickness (d) of the flat toner,
It has been experimentally confirmed that a) the flat toner remaining on the transfer is caused and is preferable to be attached to the cleaning roller 191.

The cleaning blade 192 has a thickness of about 1 to 3 mm and is formed using a plate material such as a silicone resin or a urethane resin. As shown in FIG.
The cleaning blade 192 has a thickness of 1 to 20 in which carbon is mixed with silicon resin or urethane resin on the contact side with the photosensitive drum 10 (or the photosensitive drum 10 a).
A conductive layer 192a of about μm (about the same as the volume average particle diameter of the flat toner) is provided, and the conductive layer 192a has the same polarity as the toner (minus polarity in the present embodiment), for example, −.
A second cleaning bias VC2 consisting of a DC voltage of about 100 to -500 V is applied to form an electric field E between the tip of the cleaning blade 192 and the cleaning roller 191. The transfer residue that is not cleaned by the cleaning roller 191 is transferred. Cleaning the flat toner. At this time, the photosensitive drum 10 (or the photosensitive drum 10a)
The transfer residual flat toner that has not been cleaned by the cleaning roller 191 attached to the photosensitive drum 10a (or the photosensitive drum 10a) is repelled by the electric field E, and is removed by the cleaning roller 191 attached to the photosensitive drum 10 (or the photosensitive drum 10a). The transfer residual flat toner that has not been cleaned is also cleaned. Also,
The flat toner remaining on the transfer remaining at the tip of the cleaning blade 192 is repelled by the electric field E, and the flat toner remaining on the tip of the cleaning blade 192 is cleaned. If the thickness of the conductive layer 192a is too large, an electric field cannot be formed between the tip of the cleaning blade 192 and the cleaning roller 191.
The transfer residual flat toner that has not been cleaned by the cleaning roller 191 that adheres to the photoconductor drum 10 (or the photoconductor drum 10a) and the transfer residual flat toner that accumulates at the tip of the cleaning blade 192 can be easily repelled. Not done.

As described above, in the image forming apparatus using the flat toner, it is possible to provide an image forming apparatus having a cleaning device with good cleaning performance of the transfer residual toner on the image forming body after image formation.

[0144]

According to the present invention, in an image forming apparatus using flat toner, it is possible to provide an image forming apparatus having a cleaning device having a good cleaning property of transfer residual toner on an image forming body after image formation. Become.

[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 according to the present invention.

FIG. 2 is a sectional configuration diagram of a color image forming apparatus showing a second example of the embodiment of the image forming apparatus using flat toner 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 according to the present invention.

FIG. 4 is a diagram illustrating a toner image formed of flat toner on an image forming body or an intermediate transfer body.

FIG. 5 is a schematic diagram illustrating an example of a flat toner.

FIG. 6 is a sectional view of a main part showing an example of an annular continuous wet stirring mill.

FIG. 7 is a partially enlarged explanatory view of a cleaning device that cleans flat toner using a rotating roller that applies a first cleaning bias and a blade member.

FIG. 8 is a diagram illustrating a surface state of a rotating roller.

FIG. 9 is a partially enlarged explanatory view of a cleaning device that cleans flat toner by applying a second cleaning bias to a blade member.

[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 19 Photoconductor cleaning device 100 Process unit 191 Cleaning roller 192 Cleaning blade 192a Conductive layer E Electric field P Recording paper VC1 First cleaning bias VC2 Second cleaning bias

Claims (3)

[Claims] An electrostatic latent image is formed on an image forming body, the electrostatic latent image is developed with a developer using flat toner, and a toner image is formed on the image forming body. In an image forming apparatus for transferring an image onto a transfer material and cleaning transfer residual toner on the image forming body by a cleaning unit, the cleaning unit includes a blade member and a rotating roller. An image forming apparatus, wherein a front end portion is arranged toward the rotating roller provided on an upstream side in a moving direction of the image forming body. 2. The image forming apparatus according to claim 1, wherein the rotation roller is provided with irregularities on a surface thereof, and a first cleaning bias is applied to the rotation roller. 3. The image according to claim 1, wherein a second cleaning bias is applied to the blade member to form an electric field between a tip of the blade member and the rotating roller. Forming equipment.