JP2003215888A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the load of an image-forming-body cleaning means on a photoreceptor and enable correct detection of the density of a standard density pattern, in an image forming device of an intermediate transfer system, which uses small particle-diameter toners. <P>SOLUTION: In the image forming device, small particle-diameter toners are used as a plurality of color toners and black toner. A first standard density pattern is formed on an image forming body with the black toner, and a second standard density pattern is formed on an intermediate transfer body with the plurality of color toners on the image forming body. The density of the first standard density pattern formed on the image forming body is detected by a first image density detecting means which detects the first standard density pattern. Also, the density of the second standard density pattern formed on the intermediate transfer body is detected by a second image density detecting means which detects the second standard density pattern. <P>COPYRIGHT: (C)2003,JPO

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 using an electrophotographic system such as a copying machine, a printer, and a FAX, and more particularly to an image forming apparatus using a toner having a small particle diameter as a developer.

[0002]

2. Description of the Related Art Recently, with the advent of the information age, demand for office machines such as copiers, printers and facsimiles has increased rapidly, and now, the speed of copiers, image quality and pollution-free. Characteristics such as conversion have been requested.

In order to improve the image quality of the copying machine and the like, it is necessary to improve the characteristics of the toner, and it is particularly important to reduce the particle size and use a toner having a sharp particle size distribution. I understand. Such a toner can be obtained by classifying a crude toner in the above particle size range even by a conventional pulverization and granulation method, but a large amount of toner is removed in the classifying step, so that the yield is low and the productivity is poor. There was a problem. Therefore, in recent years, a polymerized granulated toner obtained by polymerizing by a suspension polymerization method or an emulsion polymerization method has been developed and is about to be put to practical use, and a method or apparatus for forming an image using a small particle diameter toner is, for example, Japanese Patent Laid-Open No. 2000-8172
It is disclosed in Japanese Unexamined Patent Publication No. 2 and Japanese Unexamined Patent Publication No. 2001-5208. Further, as a two-component developer using such a small particle diameter toner, toner particles having a particle diameter of 7 μm or less as a toner and carrier particles having a particle diameter of 50 μm or less as a carrier corresponding thereto are well developed. It is usually used as a material capable of providing the property of transferability, transferability or cleaning property.

Further, conventionally, as an image forming apparatus utilizing an electrophotographic system, the surface of an image forming body formed of a drum-shaped photosensitive member which is rotationally driven is provided with a predetermined charging means such as a charger using corona discharge. An electrostatic latent image is formed by uniformly exposing the surface of the photoconductor to an image by means of an image exposing means using a laser optical system, which is the same as the surface potential of the photoconductor. The toner is attached to the image-exposed region of the photoreceptor by a developing unit that uses a two-component developer composed of a toner that is triboelectrically charged with a polarity (for example, a negative polarity) and a carrier (the carrier polarity is a positive polarity). A reversal development type image forming apparatus that visualizes an electrostatic latent image is widely used. Here, when the toner is attached to the image exposure area of the photoconductor, a developing roller (developer carrying body) arranged so as to face the photoconductor via the developing area of the developing means.
Is applied with a developing bias voltage having the same polarity as the surface potential of the photoconductor (for example, negative polarity).

On the other hand, conventionally, the above-mentioned reversal development method is used,
An image forming apparatus of a method (intermediate transfer method) of forming a toner image on a photoconductor, transferring these toner images onto an intermediate transfer body, and then transferring the toner image onto a transfer material, or a full-color image As an image forming apparatus for forming a toner image, a method of forming Y, M, C, and K toner images on a photoconductor in a superposed manner and then transferring the superposed toner images to a transfer material at once (multiplexing). Development intermediate transfer method), or yellow (Y), magenta (M), cyan (C), and black (K) toner images are sequentially formed on the same photoreceptor, and the toner images are transferred onto the intermediate transfer body. (Or yellow (Y), magenta (M), cyan (C) on multiple photoconductors
And black (K) toner images are respectively formed, these toner images are sequentially transferred onto an intermediate transfer member and the toner images are superposed on each other, and the superposed toner images are collectively transferred onto a transfer material. An image forming apparatus such as a method (multi-transfer intermediate transfer method) is generally used as a useful one. From the viewpoint that the image forming apparatus of the above system can use various transfer materials including thick paper, the image forming apparatus of the intermediate transfer system is preferably used. Further, in the case of forming a full-color image, in the above-mentioned color image forming method, even if various transfer materials are used, it is relatively easy to control the transfer condition, and the image quality of the full-color image is stabilized, A development intermediate transfer system or a multiple transfer intermediate transfer system is preferably used.

Further, stabilization of the image density in the image forming apparatus of the above-mentioned intermediate transfer system, multiple development intermediate transfer system, and multiple transfer intermediate transfer system, and toner concentration of a two-component developer used as a developer during image formation To stabilize
A technique is generally used in which a standard density pattern is formed on a photoconductor, the pattern density is detected by an image density detection means (photosensor), and reflected in the control of the image density and the toner density.

[0007]

However, since the standard density pattern is formed outside the image area on the photoconductor, it is not transferred to the transfer material. Therefore, a large amount of toner is transferred as untransferred toner to the photoconductor cleaning device ( Cleaning is performed by the cleaning blade (image forming body cleaning blade) of the image forming body cleaning means), and the load applied to the photoconductor by the cleaning blade becomes considerably large. When using small toner,
Since the cleaning property becomes low, there arises a problem that cleaning failure occurs on the photoconductor. If this is attempted to be cleaned, the load on the photoconductor by the cleaning blade will be further increased. Further, in the case of the multiple transfer intermediate transfer method, a larger amount of untransferred toner is cleaned, which causes a problem that the cleaning blade exerts a larger load on the photosensitive member and causes a cleaning failure on the photosensitive member. . The cleaning of the untransferred toner differs depending on the model, but for every predetermined print such as every one print or every 500 prints, the recording paper is used for the toner density detection and the gradation correction by using the standard density pattern. Toner that is not transferred onto the (transfer material) (untransferred toner) is formed on the photoconductor to detect the toner density and correct the gradation, and the toner image is cleaned. At this time, there arises a problem that cleaning failure occurs on the photoconductor as described above.

For this reason, in general, the standard density pattern is formed on the photoconductor and then transferred to an intermediate transfer member to detect the pattern density of the standard density pattern. Transfer In an image forming apparatus of the intermediate transfer system, when the standard density pattern of black toner (black toner) is transferred to the intermediate transfer body and the pattern density of the standard density pattern of the black toner is measured by the photo sensor, the intermediate transfer body Is often made of black material in which carbon is dispersed to control the electric resistance value.When detecting the pattern density of the standard density pattern of black toner on the intermediate transfer body with a photo sensor, light is absorbed by both. Therefore, the amount of reflected light is small, it is difficult to detect the change in the amount of reflected light according to the amount of toner, and the density of the pattern density cannot be detected accurately. Problem precise control of density and the toner density is not performed occurs.

The present invention solves the above problems, and an image forming apparatus of an intermediate transfer system for forming a toner image on an image forming body using a toner having a small particle size and transferring the toner image onto an intermediate transfer body. In order to solve the problem of defective cleaning of the image forming body by reducing the load on the photoconductor by the image forming body cleaning means, and to provide an image forming apparatus capable of accurately detecting the pattern density of the standard density pattern. The purpose is to

[0010]

The above-mentioned object is to perform image exposure on the surface of the image forming body, the charging means for uniformly charging the surface of the image forming body, and the surface of the image forming body charged by the charging means. The image exposing means for forming an electrostatic latent image on the image forming body and the electrostatic latent image formed on the image forming body have a volume average particle size of 3 to 7.
Reversal developing means for developing with a toner having a small particle diameter of μm to form a toner image on an image forming body, transfer means for transferring the toner image formed on the image forming body onto an intermediate transfer body, and the image forming An image forming body cleaning unit that cleans the untransferred toner remaining on the body by the image forming body cleaning member that is in contact with the surface of the image forming body, and the untransferred toner remaining on the intermediate transfer body by the intermediate In an image forming apparatus having an intermediate transfer member cleaning unit that cleans with an intermediate transfer member cleaning member that is in contact with the transfer member surface,
Black toner is used to form a first standard density pattern of the black toner on the image forming body, and a second standard density pattern of toner of a plurality of colors on the image forming body is formed on the intermediate transfer body. A first formed on the image forming body
The pattern density of the standard density pattern of the second standard density pattern is detected by the first image density detecting means for detecting the first standard density pattern, and the pattern density of the second standard density pattern formed on the intermediate transfer body is detected. An image forming apparatus (first invention) is characterized in that it is detected by a second image density detecting means for detecting the second standard density pattern.

Further, the above-mentioned object is to perform image exposure on the image forming body, charging means for uniformly charging the surface of the image forming body, and image exposure on the surface of the image forming body charged by the charging means. And an image exposing unit for forming an electrostatic latent image on the image forming body, and the electrostatic latent image formed on the image forming body is developed with a small particle size toner having a volume average particle size of 3 to 7 μm to form a toner image on the image forming body. An image forming apparatus having a reversal developing means for forming a toner image and a transfer means for transferring a toner image formed on the image forming body onto an intermediate transfer body. And a standard density pattern of toner of a plurality of colors on the image forming body is formed on the intermediate transfer body, and the pattern density of the standard density pattern of a plurality of colors formed on the intermediate transfer body is defined as the standard density pattern. Image density detection to detect the pattern density of Performs image density control by detecting by means, black toner is achieved by an image forming apparatus and performs image density control by the image density control means (second invention).

Further, the above-mentioned object is to form an image on the image forming body, a charging means for uniformly charging the surface of the image forming body, and an image exposure of the surface of the image forming body charged by the charging means. And an image exposing unit for forming an electrostatic latent image on the image forming body, and the electrostatic latent image formed on the image forming body is developed with a small particle size toner having a volume average particle size of 3 to 7 μm to form a toner image on the image forming body. In an image forming apparatus having a reversal developing means for forming a toner image and a transfer means for transferring a toner image formed on the image forming body onto an intermediate transfer body, the small particle diameter toner is black toner, and the black toner is used. An image forming apparatus for forming a standard density pattern on an intermediate transfer member, wherein at least a portion for forming the standard density pattern is a mirror surface, and the pattern density of the standard density pattern is detected (third invention. ) Achieved by That.

[0013] Further, the above-mentioned object is to form an image on the image forming body, charging means for uniformly charging the surface of the image forming body, and imagewise exposing the surface of the image forming body charged by the charging means. And an image exposing unit for forming an electrostatic latent image on the image forming body, and the electrostatic latent image formed on the image forming body is developed with a small particle size toner having a volume average particle size of 3 to 7 μm to form a toner image on the image forming body. In an image forming apparatus having a reversal developing means for forming a toner image and a transfer means for transferring a toner image formed on the image forming body onto an intermediate transfer body, the small particle diameter toner is black toner, and the black toner is used. An image forming apparatus for forming a standard density pattern on an intermediate transfer member, wherein at least a portion for forming the standard density pattern is used as a coating layer, and the pattern density of the standard density pattern is detected. Invention) It is.

Further, the above-mentioned object is to form an image on the image forming body, a charging means for uniformly charging the surface of the image forming body, and an image exposure of the surface of the image forming body charged by the charging means. And an image exposing unit for forming an electrostatic latent image on the image forming body, and the electrostatic latent image formed on the image forming body is developed with a small particle size toner having a volume average particle size of 3 to 7 μm to form a toner image on the image forming body. An image forming apparatus having a reversal developing means for forming a toner image and a transfer means for transferring a toner image formed on the image forming body onto an intermediate transfer body. A standard density pattern of at least the black toner is formed on the intermediate transfer body, and a toner layer of a color different from the standard density pattern is provided between the intermediate transfer body and the standard density pattern, Pattern density of standard density pattern It is achieved by an image forming apparatus and detecting the (fifth invention).

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. Note that the description in this section does not limit the technical scope of the claims or the meaning of terms. Further, the following affirmative description in the embodiments of the present invention shows the best mode, and does not limit the meaning or technical scope of the terms of the present invention.

An image forming process and each mechanism of a color image forming apparatus according to an embodiment of the image forming apparatus according to the present invention will be described with reference to FIGS. 1 to 10. Figure 1
FIG. 3 is a cross-sectional configuration diagram of a color image forming apparatus according to an embodiment of the image forming apparatus according to the present invention, FIG. 2 is a diagram showing a projected image of polymerized toner particles, and FIG. FIG. 4 is an enlarged view of a main part of the image forming section in FIG. 1, showing a standard density pattern according to Item 1 or 2 and an image density detection unit for detecting the pattern density of the standard density pattern.
FIG. 5 is a view showing an image density detecting means, FIG. 5 is a view showing a formation area of a standard density pattern, and FIG. 6 is a standard density pattern according to claim 3 or 4 of the present invention and a pattern density of the standard density pattern. FIG. 7 is an enlarged view of a main part of the image forming portion of FIG. 1 showing an image density detecting means and a toner density detecting sensor for detecting the image density. FIG.
3 is an enlarged view of a main part of the image forming portion of FIG. 1 showing a standard density pattern according to No. 3 and an image density detecting means for detecting the image density of the standard density pattern. FIG. FIG. 9 is an explanatory view of a surface state of the intermediate transfer body of the standard density pattern forming section according to the present invention, and FIG. 9 is an explanatory view of a surface state of the intermediate transfer body of the standard density pattern forming section according to claim 8 or 9 of the present invention. FIG. 10 is an explanatory diagram of a method for forming a standard density pattern on an intermediate transfer member according to claim 11 or 12 of the present invention.

According to FIG. 1, the present color image forming apparatus is
A color image forming apparatus using a multiple development intermediate transfer system, in which yellow, magenta, cyan, and black color toner images are multi-developed and superposed, and formed on the image forming body. The superimposed color toner images are transferred onto an intermediate transfer member and then transferred onto a transfer material at once.

In the figure, a photosensitive member 10, which is a drum-shaped image forming member, has a light-transmitting conductive material on the outer periphery of a cylindrical substrate formed of a light-transmitting member such as glass or light-transmitting acrylic resin. And a photoconductor layer of an organic photosensitive layer (OPC). The photoconductor 10 is rotated counterclockwise by an motive power from a drive source (not shown) with the transparent conductive layer being grounded.

Around the photoreceptor 10, a scorotron charger 11 as a charging means, an exposure optical system 12 as an image writing means, and a developing device 13 as a developing means are provided as a set.
The color toner image forming means for the image forming process for each color of yellow (Y), magenta (M), cyan (C) and black (K) is arranged in the rotational direction of the photoconductor 10 indicated by the arrow in the figure. And are arranged in the order of Y, M, C, K.

Scorotron charger 11 as charging means
Are attached in close proximity to the photoconductor 10 in a direction orthogonal to the moving direction of the photoconductor 10 (direction perpendicular to the paper surface in the figure). The scorotron charger 11 includes the photoconductor 10
A control grid held at a predetermined potential with respect to the organic photoreceptor layer of, and a discharge wire as a corona discharge electrode, and a charging action (negative charging in the present embodiment) is performed by corona discharge having the same polarity as the toner, A uniform potential is applied to the photoconductor 10.

The exposure optical system 12 as an image writing means,
For each color, a linear exposure element in which a plurality of LEDs (light emitting diodes) as light emitting elements for image exposure light are arranged in an array in parallel with the axis of the photoconductor 10 and a SELFOC lens as an equal magnification imaging element Is configured as an exposure unit attached to a holder, and the exposure optical system 12 for each color is attached to a cylindrical holder 20 as an exposure optical system holding member, and integrally formed inside the base of the photoreceptor 10. Housed in.
The exposure optical system 12 performs image exposure (image writing) from the back surface of the uniformly charged photoconductor 10 based on the image data of each color sent from a separate computer (not shown) and stored in the memory. , A latent image is formed on the photoconductor 10.

The developing device 13 as a developing means is a photosensitive member 1.
A two-component developer (a one-component developer may be used) that is composed of small-diameter toners of each color of yellow (Y), magenta (M), cyan (C), or black (K) that is charged to the same polarity as that of 0. ) Respectively, for example, a thickness of 0.5 to 1 m
m, an outer diameter of 15 to 25 mm, and a developing roller 13a, which is a developer carrier formed of a non-magnetic stainless steel or aluminum material. The developing roller 13a is kept in non-contact with the photoconductor 10 with a predetermined gap, for example, 100 to 1000 μm, by an abutting roller (not shown). By applying a developing bias voltage that superimposes an AC voltage on a DC voltage having a negative polarity (or negative polarity in the embodiment) or a DC voltage, non-contact reversal development is performed on the exposed portion on the photoconductor 10. The small particle size toner will be described in detail.

The transfer belt 14a as an intermediate transfer member is
Volume resistivity 10 ⁸ to 10 ¹⁵ Ω · cm, surface resistivity 10 ⁸ to
An endless belt of 10 ¹⁵ Ω / □, for example, modified polyimide, thermosetting polyimide, ethylene tetrafluoroethylene copolymer, polyvinylidene fluoride, nylon alloy, etc. On the outside of the 0.5 mm semi-conductive film substrate, preferably a thickness of 5 as a toner filming prevention layer.
It is a seamless belt having a two-layer structure and having a fluorine coating of ˜50 μm. In addition to this, a semi-conductive 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 as the base body of the transfer belt 14a. Transfer belt 14a
Is stretched around the drive roller 14d, the driven roller 14e and the tension roller 14i.

The image forming body cleaning device 19 as an image forming body cleaning means is provided with an image forming body cleaning blade 19a.
Thus, the transfer residual toner remaining on the peripheral surface of the photoconductor 10 after the transfer is cleaned.

The intermediate transfer member cleaning device 191 as an intermediate transfer member cleaning means is provided with an intermediate transfer member cleaning blade 191a, and the intermediate transfer member cleaning blade 191a cleans the transfer residual toner remaining on the transfer belt 14a after the transfer.

The image forming process (image forming process) will be described below. When image recording is started, the image forming member drive motor (not shown) is started to rotate the photoconductor 10 in the direction indicated by the arrow in the figure, and the Y scorotron charger 11 applies a potential to the photoconductor 10. After a potential is applied to the photoconductor 10, the Y exposure optical system 12 performs exposure (image writing) with an electric signal corresponding to the first color signal, that is, Y image data, and the yellow image is formed on the photoconductor 10. An electrostatic latent image corresponding to the image of (Y) is formed. This latent image is subjected to reversal development in a non-contact state by the Y developing device 13 to form a toner image composed of yellow (Y) small particle size toner on the photoconductor 10.

Then, a potential is applied to the photoreceptor 10 from above the yellow (Y) toner image by the charging action of the M scorotron charger 11, and the M exposure optical system 12 causes the second color signal, that is, magenta ( The exposure (image writing) is performed by an electric signal corresponding to the image data of M), and the non-contact reversal development by the developing device 13 of M causes the toner image of the yellow (Y) small-diameter toner to be formed. A toner image composed of magenta (M) small-sized toner is superimposed and formed on the upper surface.

By the same process, a toner image composed of cyan (C) small-sized toner and a toner image composed of black (K) small-sized toner are successively superposed and formed, and within one rotation of the photoconductor 10. On its circumference, Y, M, C and K
A superposed color toner image is formed of the small particle size toners.

The superimposed color toner image formed on the photoconductor 10 is provided in the transfer area so as to face the photoconductor 10, and a DC voltage having a polarity opposite to that of the toner (plus polarity in this embodiment) is applied. Transferred onto the transfer belt 14a by the applied primary transfer roller 14c as the primary transfer means, and Y, M, C and K are transferred onto the transfer belt 14a.
A superposed color toner image is formed of the small particle size toners. At this time, the transfer belt 14a is brought into contact with or separated from the photoconductor 10. In the separated state, the transfer belt 14a is brought into contact with the photoconductor 10 by an electrostatic adhesion force due to a DC voltage applied to the primary transfer roller 14c. It

The transfer residual toner remaining on the peripheral surface of the photoconductor 10 after the transfer is cleaned by the image forming body cleaning blade 19a of the image forming body cleaning device 19.

On the other hand, in parallel with the transfer of the superimposed color toner images onto the transfer belt 14a, the recording paper P as a transfer material is sent out from the paper feed cassette 15 as a transfer material storage means by the sending roller 15a, Feed roller 1
Timing roller 1 as a transfer material feeding means via 5b
It is transported to 6. Further, the recording paper P is the transfer belt 14
Synchronized with the superimposed color toner image formed on a, the toner is sent out from the timing roller 16 to a transfer area where the secondary transfer roller 14g as the second transfer means and the transfer belt 14a face each other. Transported, in the transfer area,
Polarity opposite to toner (plus polarity in this embodiment)
By the secondary transfer roller 14g to which the voltage is applied, the superimposed color toner images on the transfer belt 14a are collectively transferred onto the recording paper P.

The recording paper P on which the superimposed color toner images have been transferred is conveyed to the fixing device 17, and in the fixing device 17, a fixing roller 17a having a halogen lamp HLa as a heating element therein and a pressure roller 17b. The recording paper P is nipped and conveyed by the fixing roller 17a and the pressure roller 1.
The heat and pressure are added to the nip portion N formed between the recording paper P and 7b to fix the superimposed color toner image on the recording paper P, and then the recording paper P passes through the paper discharge roller 18 and the upper portion of the apparatus. Will be ejected to the tray.

The toner remaining on the peripheral surface of the transfer belt 14a after the transfer is cleaned by the intermediate transfer member cleaning blade 191a of the intermediate transfer member cleaning device 191, and the next image forming cycle is started.

In the above image forming apparatus, yellow (Y), magenta (M), cyan (C) and black (K) toner images are sequentially formed on the same photoconductor, and these toner images are intermediately formed. An image forming apparatus of a system (multi-developing intermediate transfer system) in which a toner image is transferred onto a transfer body and superposed thereon, and then the superposed toner images are collectively transferred onto a transfer material has been described. Yellow (Y), magenta (M), cyan (C) and black (K) on the image forming body
Toner images are formed, these toner images are sequentially transferred onto an intermediate transfer member, the toner images are superposed, and then the superposed toner images are collectively transferred onto a transfer material (multi-transfer intermediate The present invention is also applied to a transfer type image forming apparatus. Further, although the color image forming apparatus has been described as the description of the image forming apparatus, the present invention is also applied to an image forming apparatus of a system (intermediate transfer system) for performing monochrome image formation.

In the image forming apparatus described above, it is preferable to use a two-component developer containing a polymerized toner (small particle size toner) having a small particle size and a magnetic carrier having a small particle size. Particularly has a mass average particle size of 20 to 5
A two-component developer containing a carrier of 0 μm and a polymerized toner having a mass average particle diameter in the range of 3 to 7 μm is preferable.

Details of the small particle size polymerized toner (small particle size toner) and the carrier used in the two-component developer will be described below.

First, the polymerized toner used in the present invention will be described with reference to FIG. FIG. 2A is an explanatory diagram showing a projected image of polymerized toner particles without corners.
(B) and (C) are explanatory views showing projected images of polymerized toner particles each having corners.

The polymerized toner used in the image forming apparatus of the present invention has (1) 65 number% or more of toner particles having a shape factor of 1.2 to 1.6, and a variation coefficient of the shape factor of 16 %, And (2) toner particles having a shape coefficient variation coefficient of 16% or less and a number variation coefficient of number particle size distribution of 27% or less, ( 3) It is preferable that the toner particles are composed of toner particles in which the proportion of polymerized toner particles having no corners is 50% by number or more, or a combination thereof.

In the present invention, the shape factor of the polymerized toner is represented by the following formula and represents the degree of roundness of the polymerized toner particles.

Shape factor = ((maximum diameter / 2) ² × π) / projected area Here, the maximum diameter is the parallel line when a projected image of toner particles on a plane is sandwiched by two parallel lines. Refers to the width of the particles at which the interval is maximum. The projected area means the area of the projected image of the toner particles on the plane.

In the present invention, this shape factor is obtained by taking a photograph of the toner particles magnified 2000 times with a scanning electron microscope, and then, based on the photograph, "SCANNING" is taken.
It was measured by analyzing a photographic image using "IMAGE ANALYZER" (manufactured by JEOL Ltd.). At this time, the shape factor of the present invention was measured by the above calculation formula using 100 toner particles.

In the polymerized toner used in the present invention, the number of toner particles having the shape factor in the range of 1.2 to 1.6 is preferably 65% by number or more, more preferably 70% by number or more. .

When the number of toner particles having the shape factor in the range of 1.2 to 1.6 is 65% by number or more, the triboelectrification property with carrier particles becomes more uniform,
Accumulation of excessively charged toner can be reduced, and toner can be more smoothly conveyed by carrier particles, so that problems such as development ghosts are less likely to occur. Further, the toner particles are less likely to be crushed, the contamination of the charging member (charging device) is reduced, and the charging property of the toner can be stabilized.

The method of controlling the shape factor is not particularly limited. For example, a method of spraying toner particles in a hot air stream, a method of repeatedly applying mechanical energy by impact force in a gas phase in a gas phase, or a method of adding a toner to a solvent that does not dissolve toner to give a swirling flow, etc. According to the method described above, a toner having a shape factor of 1.2 to 1.6 is prepared, and this is added to a normal toner so as to be within the range of the present invention, and then adjusted. Also, controlling the overall shape at the stage of adjusting the so-called polymerization method toner,
There is a method in which a toner whose shape factor is adjusted to 1.2 to 1.6 is similarly added to an ordinary toner to prepare.

The variation coefficient of the shape factor of the polymerized toner preferably used in the image forming apparatus of the present invention is calculated by the following formula.

Coefficient of variation = (S / K) × 100 (%) In the formula, S represents the standard deviation of the shape factors of 100 toner particles, and K represents the average value of the shape factors.

In the polymerized toner used in the image forming apparatus of the present invention, the variation coefficient of the shape factor is 16
% Or less, and more preferably 14% or less. When the variation coefficient of the shape factor is 16% or less, the voids of the transferred toner layer are reduced, the fixability is improved, and the offset is less likely to occur. In addition, the charge amount distribution becomes sharp and the image quality is improved.

In order to uniformly control the shape factor of the toner and the variation coefficient of the shape factor without extremely lot-to-lot variation, the toner is formed in the step of polymerizing, fusing and controlling the shape of the resin particles (polymer particles). An appropriate process end time may be determined while monitoring the characteristics of certain toner particles (colored particles).

Monitoring means that a measuring device is installed in-line and the process conditions are controlled based on the measurement result. That is, in the case of a polymerization toner in which measurement of a shape or the like is incorporated inline, for example, a resin toner is formed by associating or fusing resin particles in an aqueous medium, the shape and the particle size are measured while performing sequential sampling in the steps such as fusing. Is measured, and the reaction is stopped when the desired shape is obtained.

The monitoring method is not particularly limited, but a flow type particle image analyzer FPIA-
2000 (manufactured by Toa Medical Electronics Co., Ltd.) can be used. This device is suitable because the shape can be monitored by performing image processing in real time while passing the sample liquid. That is, a pump or the like is used from the reaction field to constantly monitor and measure the shape and the like, and the reaction is stopped when the desired shape or the like is obtained.

The number particle size distribution and number variation coefficient of the polymerized toner used in the image forming apparatus of the present invention are measured by Coulter Counter TA-II or Coulter Multisizer (manufactured by Coulter Co.). In the present invention, a Coulter Multisizer was used, and an interface (manufactured by Nikkaki Co., Ltd.) for outputting the particle size distribution and a personal computer were connected and used. The aperture used in the Coulter Multisizer was 100 μm, and the volume and number of 2 μm or larger toners were measured to calculate the particle size distribution and mass average particle size. The number particle size distribution represents the relative frequency of toner particles with respect to the particle size, and the mass average particle size represents the median diameter in the number particle size distribution. The number variation coefficient in the number particle size distribution of the toner is calculated from the following formula.

Number variation coefficient = (S / Dn) × 100 (%) In the formula, S represents the standard deviation in the number particle size distribution,
Dn indicates a mass average particle diameter (μm).

In the polymerized toner used in the image forming apparatus of the present invention, the number variation coefficient is preferably 27% or less, more preferably 25% or less. When the number variation coefficient is 27% or less, the voids of the transferred toner layer are reduced, the fixing property is improved, and the offset hardly occurs. Further, the charge amount distribution becomes sharp, the transfer efficiency is improved, and the image quality is improved.

The method of controlling the number variation coefficient is not particularly limited. For example, a method of classifying toner particles by wind force can be used, but classification in a liquid is effective for reducing the number variation coefficient. As a method of classifying in this liquid, there is a method of controlling the number of revolutions and separately collecting and preparing toner particles according to the difference in sedimentation speed caused by the difference in toner particle diameter.

Particularly when a toner is produced by the suspension polymerization method, a classification operation is indispensable in order to keep the number variation coefficient in the number particle size distribution at 27% or less. In the suspension polymerization method,
Before the polymerization, it is necessary to disperse the polymerizable monomer into an oil droplet having a desired size as a toner in an aqueous medium. That is, the large oil droplets of the polymerizable monomer are repeatedly mechanically sheared by a homomixer or a homogenizer to reduce the oil droplets to the size of toner particles. In the method of different shearing, the number particle size distribution of the obtained oil droplets becomes wide, and therefore,
The toner obtained by polymerizing this also has a wide particle size distribution. For this reason, classification operation is essential.

In the polymerized toner used in the image forming apparatus of the present invention, the polymerized toner particles having no corners are toners having substantially no protrusions where electric charges are concentrated or protrusions which are easily worn by stress. Particles,
That is, as shown in FIG. 2 (A), when the major axis of the toner particles T is L, a circle C having a radius (L / 10) is in contact with the peripheral line of the toner particles T at one point while The case where the circle C does not substantially protrude to the outside of the toner T when the inside is rolled is referred to as “a corner-free polymerized toner particle”. The term “when substantially not protruding” means a case where there is one or less protrusions with protruding circles. Also,
The “major axis of polymerized toner particles” refers to the width of the particles that maximizes the distance between the parallel lines when the projected image of the polymerized toner particles on a plane is sandwiched by two parallel lines. Note that FIG.
(B) and (C) show projected images of the polymerized toner particles having corners, respectively.

The corner-free polymerized toner was measured as follows. First, an enlarged photograph of the polymerized toner particles was taken with a scanning electron microscope, and further magnified to 15,000.
A 0x photographic image is obtained. Then, the presence or absence of the above-mentioned corner is measured for this photographic image. This measurement was performed on 100 polymerized toner particles.

In the polymerized toner used in the present invention, the proportion of cornerless polymerized toner particles is preferably 50% by number or more, more preferably 70% by number or more. The percentage of polymerized toner particles without corners is 50% by number
By the above, the generation of fine particles due to stress with the carrier particles is less likely to occur, the adhesion of the carrier particles to the surface of the carrier particles can be prevented from being present excessively large, and to the carrier particles Contamination can be suppressed. In addition, the polymerized toner particles that are easily worn or broken and the polymerized toner particles that have a portion where electric charge is concentrated are reduced, the charge amount distribution becomes sharp, the chargeability is stable, and a high-quality image is stable for a long time. Can be formed as desired.

The method for obtaining a cornerless polymerized toner is not particularly limited. For example, as described above as a method of controlling the shape factor, a method of spraying toner particles in a hot air flow, a method of repeatedly applying mechanical energy due to impact force in a gas phase, or a method of dissolving toner It can be obtained by adding it to a solvent that does not contain it and imparting a swirling flow.

Further, in the polymerized toner formed by associating or fusing resin particles, the surface of the fused particles has many irregularities at the step of stopping the fusion, and the surface is not smooth, but the shape control step Corner-free toner particles can be obtained by appropriately adjusting the conditions such as the temperature, the rotating speed of the stirring blade, and the stirring time. These conditions are
Although it depends on the physical properties of the resin particles, for example, by setting the glass transition temperature of the resin particles or higher to a higher rotation speed, the surface becomes smooth and toner particles without corners can be formed.

The polymerized toner used in the image forming apparatus of the present invention preferably has a mass average particle diameter of 3 to 7 μm. When the toner particles are formed by a polymerization method, the particle size of the polymerized toner can be controlled by the concentration of the aggregating agent, the addition weight of the organic solvent, the desorption time, and the composition of the polymer itself.

Since the mass average particle diameter of the polymerized toner is 3 to 7 μm, it is possible to reduce the presence of a toner having an excessively large adherence to the carrier or a toner having a low adherence in the fixing step, which is excellent. The developability can be stably obtained over a long period of time, the transfer efficiency is improved, the halftone image quality is improved, and the image quality of fine lines, dots, etc. is improved. Mass average particle size of polymerized toner is 3μ
If it is smaller than m, the image quality is apt to be deteriorated due to fogging, and if it is larger than 7 μm, the characteristic of high image quality becomes thin.

Particles used as a carrier are iron,
Conventionally known magnetic particles such as metals such as ferrite and magnetite and alloys of these metals with metals such as aluminum and lead can be used, and ferrite particles are particularly preferably used. The carrier particles used for the polymerized toner having a small particle diameter of 3 to 7 μm are preferably those having a small particle diameter of 20 to 50 μm as the mass average particle diameter. The mass average particle diameter of carrier particles is typically measured by a laser diffraction type particle size distribution measuring apparatus “HELOS” (sympathic (SY
Manufactured by MATETEC). As the carrier, the above magnetic particles can be used as they are, but a carrier coated with a resin or a so-called resin dispersion type carrier in which magnetic particles are dispersed in a resin is preferable. The resin composition for coating is not particularly limited, but for example, an olefin resin, a styrene resin, a styrene / acrylic resin, a silicon resin, an ester resin, a fluorine-containing polymer resin, or the like is used. The resin for forming the resin-dispersed carrier is not particularly limited, and known ones can be used. For example, styrene / acrylic resin, polyester resin, fluorine resin, phenol resin, etc. can be used. You can When the mass average particle diameter of the carrier is smaller than 20 μm, carrier adhesion is likely to occur, and the carrier is 50 μm.
If it is larger than the above range, deterioration of the image quality such as density unevenness called "crimping" is likely to occur in the image.

As described at the beginning, it is used as a developer when stabilizing the image density in the image forming apparatus of the above-mentioned intermediate transfer system, multiple development intermediate transfer system, and multiple transfer intermediate transfer system, and during image formation. In order to stabilize the toner density of the two-component developer, in general, a standard density pattern is formed on the photoconductor 10 and the pattern density is detected by an image density detecting means (photosensor) to Although an attempt is made to properly control the toner density, the standard density pattern is not transferred to the recording paper P because the position on the photoconductor 10 is formed outside the image area. Therefore, a large amount of toner is not transferred yet. The image forming body cleaning blade 19 of the image forming body cleaning device 19 is used for cleaning.
The load applied to the photoconductor 10 is considerably increased by 9a. When a toner having a small particle diameter is used, the cleaning property is lowered, and thus cleaning failure occurs on the photoconductor 10. If this is attempted to be cleaned, the load on the photoconductor by the image forming body cleaning blade 19a will be further increased. Further, in the case of the multiple transfer intermediate transfer method, a larger amount of untransferred toner is cleaned, and the load on the photoconductor 10 by the image forming member cleaning blade 19a is further increased, resulting in defective cleaning of the photoconductor 10. I will end up. For this reason, generally, the standard density pattern is formed on the photoconductor 10 and then transferred to the intermediate transfer member to detect the pattern density of the standard density pattern. However, the above-mentioned intermediate transfer method or multiple transfer intermediate transfer is performed. In the image forming apparatus of the method, when the standard density pattern of black toner (black toner) is transferred to the transfer belt 14a and then the pattern density of the standard density pattern of black toner is measured by the photosensor, the transfer belt 14a has an electrical resistance. In many cases, carbon is dispersed to control the value and is made of a black material. When the pattern density of the standard density pattern of the black toner is detected by the photosensor on the transfer belt 14a, light is absorbed together. Since the amount of reflected light is small, it is difficult to detect the change in the amount of reflected light according to the amount of toner, and the density of pattern density can be accurately detected. , Precise control of the image density and the toner density is not performed.

In order to solve the above problem, as shown in FIG. 3, a standard pattern PTa of K toner as a first standard density pattern of black toner (K toner) is formed on the photoconductor 10.
The pattern density of the K toner standard pattern PTa formed on the photoconductor 10 is detected by the K toner photosensor PSa as the first image density detecting means. The black (K) image density and the toner density are controlled according to the pattern density detected by the K toner photosensor PSa. Further, Y, M, and C as a second standard density pattern formed by a plurality of color toners of yellow, magenta, and cyan (Y, M, C) formed on the photoconductor 10.
The standard pattern PTb of toner is transferred onto the transfer belt 14a to form the standard pattern PTb of Y, M and C toners on the transfer belt 14a, and the standard pattern PTb of Y, M and C toners formed on the transfer belt 14a is transferred. The pattern density of the standard pattern PTb is set to Y, M, C as the second image density detecting means.
It is detected by the toner photo sensor PSb. Y, M,
The image density and toner density of yellow, magenta, and cyan (Y, M, C) are controlled according to the pattern density detected by the C toner photosensor PSb.
The standard pattern PTb (untransferred toner) of the Y, M, and C toners on the transfer belt 14a after detection is cleaned by the intermediate transfer body cleaning blade 191a of the intermediate transfer body cleaning device 191 described above.

As for the K toner, the pattern density of the K toner standard pattern PTa on the photoconductor 10 is detected by the K toner photosensor PSa on the photoconductor 10 before the standard pattern PTa on the photoconductor 10 reaches the transfer belt 14a. Of the standard pattern PTa on the transfer belt 14a.
The standard pattern PTa (untransferred toner) of K toner transferred onto the surface 4a is transferred to the intermediate transfer member cleaning device 1
Cleaning is performed by the intermediate transfer member cleaning blade 191 a.

Depending on the model, for each predetermined print such as every one print or every 500 prints, the toner density detection and the gradation correction are performed by using the first and second standard density patterns. Toner that is not transferred onto the recording paper P (untransferred toner) is formed on the photoconductor 10 or the transfer belt 14a to detect the toner density and correct the gradation, and the untransferred toner is cleaned.

As shown in FIG. 4 (A), the K toner photosensor PSa for detecting the pattern density of the K toner standard pattern PTa faces the photoconductor 10 as shown in FIG.
For example, a standard pattern of K toner is used in which a light receiving device PD1 including a light collecting element WS1 using a light emitting diode and a projection lens La is arranged in parallel with a light receiving device PD2 including a condenser lens Lb and a light receiving device WS2. The light emitting device PD1 and the light receiving device PD2 are activated during the passage of PTa, and the pattern density of the standard pattern PTa of K toner is measured from the value of the current flowing through the light receiving element WS2. As the photosensor PSb for the Y, M, and C toners, which detects the pattern density of the standard pattern PTb for the Y, M, and C toners, as shown in FIG.
As shown in (B), a photosensor PSa having the same structure as the K toner photosensor PSa is used, and photosensors PSb for the Y, M, and C toners are provided facing the transfer belt 14a.
Light emitter P when the standard pattern PTb of M and C toners is passed
D1 and the photodetector PD2 are activated, and the photodetector WS2
The pattern density of the standard pattern PTb of the Y, M and C toners is measured from the value of the current flowing through

As shown in FIG. 5A, the formation area of the standard pattern PTa of K toner is the standard pattern PTa of K toner outside the image area on the photoconductor 10 with respect to the moving direction of the photoconductor 10. A region Ra for forming is provided. Further, the formation area of the standard pattern PTb of the Y, M and C toners is
As shown in FIG. 5B, Y, outside the image area on the transfer belt 14a with respect to the moving direction of the transfer belt 14a,
An area Ra for forming the standard patterns PTb of M and C toners is provided. As will be described later in detail, when the standard pattern PTa of K toner is formed on the transfer belt 14a, the area Ra for forming the standard pattern PTa of K toner is provided outside the image area on the transfer belt 14a. In the above figures (A) and (B), the area Ra in which the standard pattern PTa of K toner and the standard pattern PTb of Y, M, and C toner is formed is the tip of the image area or between the image areas. It is also possible to provide.

As described above, even when the small particle size toner is used, the toner other than the black toner detects the pattern density of the second standard density pattern on the intermediate transfer body, and the black toner is the first on the image forming body. By detecting the pattern density of the standard density pattern, the amount of toner of the first standard density pattern to be cleaned on the image forming body is reduced, so that the load on the image forming body by the image forming body cleaning unit is reduced. In addition to reducing the cleaning failure of the image forming body, the pattern density of the second standard density pattern of the toners of a plurality of colors is accurately detected, and the image density and the toner density can be accurately controlled. It is possible to provide the forming device.

Further, after detecting the pattern density of the first standard density pattern of the black toner on the image forming body, the first standard density pattern is transferred onto the intermediate transfer body to clean the first standard density pattern. By performing the above, it is possible to further reduce the cleaning load on the image forming body by the image forming body cleaning means, and it is possible to reduce the first toner of the black toner.
The pattern density of the standard density pattern is accurately detected, and the image density and toner density can be accurately controlled.

In order to solve the above-mentioned problem, as shown in FIG. 6, a plurality of color toners of yellow, magenta, and cyan (Y, M, C) other than K toner (black toner) are on the transfer belt 14a. After transferring the standard pattern PTb of Y, M, and C toners to the photosensor, the pattern density is used as a photosensor PS of Y, M, and C toners as an image density detecting means.
b, and the developing roller 13 is detected according to the detected value.
The rotation speed of a is changed to control the output image density of yellow, magenta, and cyan (Y, M, C). Further, the K toner does not form a standard density pattern, and the toner density in the two-component developer is detected by the image density control means, for example, the toner density detection sensor TD shown in the figure, and the toner density in the two-component developer is kept constant. Controlled to output black (K)
To stabilize the image density of. The same image density detecting means as the second image density detecting means described above with reference to FIG. 3 is used. The standard pattern PTb (untransferred toner) of Y, M, and C toners on the transfer belt 14a after detection is the intermediate transfer member cleaning device 191 described above.
It is cleaned by the intermediate transfer member cleaning blade 191a.

Although it depends on the model, for example, for every predetermined print such as every one print or every 500 prints, it is transferred onto the recording paper P for the toner density detection and the gradation correction by using the standard density pattern. The untransferred toner (untransferred toner) is formed on the transfer belt 14a, the toner density is detected and the gradation is corrected, and the untransferred toner is cleaned.

Y as an image density detecting means for detecting the pattern density of the standard pattern PTb of Y, M and C toners,
As the photosensor PSb for the M and C toners, the one similar to that described above with reference to FIG. 4B is used, and the photosensors PSb for the Y, M, and C toners are provided to face the transfer belt 14a. , The light emitting device PD1 and the light receiving device PD2 are activated when the standard pattern PTb of the C toner is passed, and the pattern density of the standard pattern PTb of the Y, M, and C toners is measured from the value of the current flowing through the light receiving element WS2.

Further, standard patterns PT of Y, M and C toners
As for the formation area of b, the transfer belt 1 is formed in the moving direction of the transfer belt 14a in the same manner as described above with reference to FIG.
A standard pattern PTb of Y, M and C toners is formed in a region Ra outside the image region on 4a.

As described above, even when the toner having a small particle diameter is used, the toner other than the black toner controls the image density by detecting the pattern density of the standard density pattern on the intermediate transfer member, and the black toner uses the standard density pattern. Without forming
The image density is controlled by controlling the mass ratio of the toner in the two-component developer as the image density detecting means, so that the standard density pattern for cleaning on the image forming body is not formed and thus the image is formed. The load on the image forming body by the body cleaning unit is reduced to eliminate the defective cleaning of the image forming body, and the image density of the toners of a plurality of colors and the black toner is controlled, so that the image density and the toner density can be accurately controlled. It is possible to provide a possible image forming apparatus.

However, when the standard density pattern of black toner (black toner) is transferred to the intermediate transfer member and then the pattern density of the standard density pattern of black toner is measured by the photosensor, the intermediate transfer member has an electric resistance value of Many are made of black material in which carbon is dispersed for control.When the photosensor detects the pattern density of the standard density pattern of black toner on the intermediate transfer body, the amount of reflected light is absorbed because both are absorbed. The black toner is particularly difficult to detect the change in the amount of reflected light depending on the toner amount, and the density of the pattern density of the black toner is not accurately detected, and the black toner image density and toner density are accurately controlled. I don't know.

In order to solve the above problem, as shown in FIG. 3, a standard pattern PTa of K toner as a first standard density pattern of black toner (K toner) is formed on the photoconductor 10.
After being formed on the photoconductor 10, the standard pattern PTa of K toner as the standard density pattern formed on the photoconductor 10 is transferred onto the transfer belt 14a, and the standard pattern PTa of K toner (untransferred) is transferred onto the transfer belt 14a. Toner) is formed, and the pattern density of the standard pattern PTa of K toner formed on the transfer belt 14a is detected by a K toner photosensor PSa as an image density detecting unit provided facing the transfer belt 14a. This transfer belt 14a
When the pattern density of the K toner photosensor PSa of the above K toner standard pattern PTa is detected, light is absorbed by the transfer belt 14a, and the amount of light reflected from the K toner standard pattern PTa is reduced. Since the change in the amount of reflected light of the K toner depending on the amount is not accurately detected, it is described below so as to prevent this, improve the reflected light, and accurately detect the change in the amount of reflected light of the K toner. Take measures.

First, as shown in FIG. 8, at least the area Ra (see FIG. 5) in which the standard pattern PTa of K toner (untransferred toner) is formed is a mirror surface, and the standard pattern PTa of K toner is used. The pattern density of is detected. Specifically, the standard pattern PTa of K toner
When the volume average particle diameter of the K toner forming the toner image is r, at least the standard pattern P of the K toner on the transfer belt 14a.
The surface roughness of the mirror surface of the region Ra forming Ta is 0.05r.
The following is preferable. K toner photo sensor P
The black (K) image density and the toner density are controlled according to the pattern density detected by Sa. Standard pattern PTa of K toner on the transfer belt 14a after detection
(Untransferred toner) is transferred to the intermediate transfer member cleaning blade 191 of the intermediate transfer member cleaning device 191 described above.
Clean with a.

Although it varies depending on the model, for example, for every predetermined print such as every one print or every 500 prints, the standard density pattern is used to transfer the toner onto the recording paper P for toner density detection and gradation correction. The untransferred toner (untransferred toner) is formed on the transfer belt 14a, the toner density is detected and the gradation is corrected, and the untransferred toner is cleaned.

As the K toner photosensor PSa as the image density detecting means for detecting the pattern density of the K toner standard pattern PTa, the same sensor as described above with reference to FIG. 4A is used. The sensor PSa is provided so as to face the transfer belt 14a, the light emitting device PD1 and the light receiving device PD2 are activated during the passage of the standard pattern PTa of K toner, and the standard pattern PTa of K toner is obtained from the value of the current flowing through the light receiving element WS2. Pattern density is measured.

Further, as the formation area of the standard pattern PTa of the K toner, the transfer belt 14 described above with reference to FIG.
A standard pattern PTa of K toner is formed in a region Ra outside the image region on the transfer belt 14a with respect to the moving direction of a. Thus, by forming the standard density pattern of black toner outside the image area, the image forming speed can be increased.

Note that the above matters are Y, M, other than K toner.
The same applies to the C toner.

As described above, even when the toner having a small particle size is used, a standard density pattern of black toner is formed on the intermediate transfer member, and a portion of the intermediate transfer member where the standard density pattern of black toner is formed is used as a mirror surface. By detecting the pattern density of the density pattern, the reflection efficiency of the detection light on the surface of the pattern density detection part of the standard density pattern of the intermediate transfer member is improved, and it is possible to detect the change in the reflected light amount according to the toner amount of black toner. It is possible to provide a good image forming apparatus. Also,
By setting the surface roughness of the mirror surface to be 0.05r or less with respect to the volume average particle size r of the small particle size toner, the pattern density of the standard density pattern is detected to detect the pattern density detection unit of the standard density pattern of the intermediate transfer member. The reflection efficiency of the detection light on the surface is further improved, and the change in the reflection light amount according to the toner amount of the black toner is further detected.

Second, as shown in FIG. 9, at least K
The area Ra (see FIG. 5) where the standard toner pattern PTa (untransferred toner) is formed is used as the coating layer, and the pattern density of the standard K toner pattern PTa is detected. Specifically, it is preferable that the coating layer of the region Ra forming the standard pattern PTa of K toner is a color other than black, for example, yellow that is difficult to absorb the reflected light of the photosensor PSa of K toner. The application may be performed only on the part where the standard density pattern is formed or on the entire surface of the transfer belt 14a. The black (K) image density and the toner density are controlled according to the pattern density detected by the K toner photosensor PSa. K toner standard pattern P on the transfer belt 14a after detection
Ta (untransferred toner) is transferred to the intermediate transfer member cleaning blade 1 of the intermediate transfer member cleaning device 191 described above.
Clean with 91a.

Although it depends on the model, for example, for every predetermined print such as every one print or every 500 prints, it is transferred onto the recording paper P for the purpose of toner density detection and gradation correction using the standard density pattern. The untransferred toner (untransferred toner) is formed on the transfer belt 14a, the toner density is detected and the gradation is corrected, and the untransferred toner is cleaned.

As the K toner photosensor PSa as the image density detecting means for detecting the pattern density of the K toner standard pattern PTa, the same sensor as described above in FIG. 4A is used. The sensor PSa is provided so as to face the transfer belt 14a, the light emitting device PD1 and the light receiving device PD2 are activated during the passage of the standard pattern PTa of K toner, and the standard pattern PTa of K toner is obtained from the value of the current flowing through the light receiving element WS2. Pattern density is measured.

Further, as the formation area of the standard pattern PTa of the K toner, the transfer belt 14 described above with reference to FIG.
A standard pattern PTa of K toner is formed in a region Ra outside the image region on the transfer belt 14a with respect to the moving direction of a. Thus, by forming the standard density pattern of black toner outside the image area, the image forming speed can be increased.

As described above, even when a small particle size toner is used, a standard density pattern of black toner is formed on the intermediate transfer member, and a portion of the intermediate transfer member where the standard density pattern of black toner is formed is used as a coating layer. By detecting the pattern density of the standard density pattern, the reflection efficiency of the detection light on the surface of the pattern density detection part of the standard density pattern is improved, and the image in which the change in the reflected light amount according to the toner amount of black toner can be detected well It is possible to provide the forming device. In addition, by using a coating layer of a color other than black and detecting the pattern density of the standard density pattern, the reflection efficiency of the detection light on the surface of the pattern density detection part of the standard density pattern is further improved, and the amount of black toner is reduced. Accordingly, the change in the reflected light amount corresponding to the detection can be further improved.

Thirdly, the standard pattern PTa of K toner is formed on the transfer belt 14a, but a toner of a color different from the standard pattern PTa of K toner is provided between the transfer belt 14a and the standard pattern PTa of K toner. A layer is provided, and the pattern density of the K toner standard pattern PTa is detected by the K toner photosensor PSa. That is, the standard pattern PTa of K toner is formed on the transfer belt 14a in order to control the image density of K toner and the toner density in the developer, but another color toner, for example, yellow (Y), is formed between the two. The toner layer is developed and transferred to the tip of the K toner standard pattern PTa, and the pattern density of the K toner standard pattern PTa is detected by the K toner photosensor PSa. Specifically, as shown in FIG. 10, the standard pattern PTc of the Y toner formed on the photoconductor 10 having a size corresponding to the area Ra (see FIG. 5) in which the standard pattern PTa of the K toner is formed is transferred. After transferring on the belt 14a,
Standard pattern PTa of K toner formed on the photoconductor 10
Is the standard pattern PT of the Y toner on the transfer belt 14a.
The pattern density of the standard pattern PTa of K toner is transferred to the photosensor PSa
To detect. Standard pattern PTa of K toner and standard pattern PT of Y toner on the transfer belt 14a after detection
The toner layer (untransferred toner) superposed on c is cleaned by the intermediate transfer body cleaning blade 191a of the intermediate transfer body cleaning device 191 described above.

Although it depends on the model, for example, every predetermined print, such as every one print or every 500 prints, is transferred onto the recording paper P using the standard density pattern for toner density detection and gradation correction. The untransferred toner (untransferred toner) is formed on the transfer belt 14a, the toner density is detected and the gradation is corrected, and the untransferred toner is cleaned.

As the K toner photosensor PSa as an image density detecting means for detecting the pattern density of the K toner standard pattern PTa, the same sensor as described above with reference to FIG. 4A is used. The sensor PSa is provided so as to face the transfer belt 14a, the light emitting device PD1 and the light receiving device PD2 are activated during the passage of the standard pattern PTa of K toner, and the standard pattern PTa of K toner is obtained from the value of the current flowing through the light receiving element WS2. Pattern density is measured.

Further, as the formation area of the standard pattern PTa of the K toner, the transfer belt 14 described above with reference to FIG.
A standard pattern PTa of K toner is formed in a region Ra outside the image region on the transfer belt 14a with respect to the moving direction of a. Thus, by forming the standard density pattern of black toner outside the image area, the image forming speed can be increased.

Note that the above matters are Y, M, other than K toner.
The same applies to the C toner.

As described above, even when the small particle size toner is used, at least the standard density pattern of black toner is formed on the intermediate transfer body, and the intermediate transfer body of the intermediate transfer body forms the standard density pattern of black toner. By providing a toner layer of a color different from that of the black toner standard density pattern between the black toner standard density pattern and the black toner standard density pattern and detecting the pattern density of the black toner standard density pattern, the non-black toner layer detects light. Is reflected, it is possible to provide an image forming apparatus in which the change in the reflected light amount according to the toner amount of black toner can be detected well.

In the above description, the pattern density of the standard pattern PTa of K toner formed on the transfer belt 14a is detected by the photosensor PSa of K toner which detects the pattern density of the standard pattern PTa of K toner. The toner concentration in the two-component developer may be controlled. As a result, the pattern density of the standard density pattern of black toner is accurately detected, and the image density and toner density can be accurately controlled. Further, it is preferable that the transfer belt 14a is black, which makes it possible to detect the change in the reflected light amount according to the toner amount of the black toner even better.

The above matters are Y, M, other than K toner.
The same applies to the C toner.

[0098]

According to the first aspect of the present invention, even when the small particle size toner is used, the toner other than the black toner detects the pattern density of the second standard density pattern on the intermediate transfer member, and the black toner forms an image. By detecting the pattern density of the first standard density pattern on the body, the toner amount of the first standard density pattern to be cleaned on the image forming body is reduced, so that the image forming body cleaning unit forms an image. The load on the body is reduced, the cleaning failure of the image forming body is eliminated, and the pattern density of the second standard density pattern of the toners of a plurality of colors is accurately detected, so that the image density and the toner density are accurately determined. It is possible to provide a controllable image forming apparatus.

According to the second aspect, after detecting the pattern density of the first standard density pattern of the black toner on the image forming body, the first standard density pattern is transferred onto the intermediate transfer body and then the first standard density pattern is transferred. By cleaning the standard density pattern, the cleaning load on the image forming body by the image forming body cleaning means can be further reduced, and
Accurate density detection of the pattern density of the first standard density pattern of black toner is performed, and accurate control of image density and toner density becomes possible.

According to the third or fourth aspect of the invention, even when the small particle size toner is used, the toner other than the black toner is subjected to the image density control by detecting the pattern density of the standard density pattern on the intermediate transfer member to control the black density. The toner is not used to form a standard density pattern, but the image density is controlled by controlling the mass ratio of the toner in the two-component developer as an image density detecting means. Since the density pattern is not formed, the load on the image forming body by the image forming body cleaning unit is reduced, the defective cleaning of the image forming body is eliminated, and the image density control of the toners of a plurality of colors and the black toner is performed. ,
It is possible to provide an image forming apparatus capable of accurately controlling the image density and the toner density.

According to the fifth aspect, even when the small particle diameter toner is used, the standard density pattern of black toner is formed on the intermediate transfer member, and the portion of the intermediate transfer member where the standard density pattern of black toner is formed is a mirror surface. As a result, by detecting the pattern density of the standard density pattern, the reflection efficiency of the detection light on the surface of the pattern density detection part of the standard density pattern of the intermediate transfer member is improved, and the change of the reflected light quantity according to the toner amount of black toner It is possible to provide an image forming apparatus in which the detection of the

According to the sixth aspect, the surface roughness of the mirror surface is set to 0.05 r or less with respect to the volume average particle size r of the small particle size toner, and the pattern density of the standard density pattern is detected to perform the intermediate transfer. The reflection efficiency of the detection light on the surface of the pattern density detection portion of the standard density pattern of the body is further improved, and the change in the reflected light amount according to the toner amount of the black toner is further detected.

According to the seventh aspect, the image forming speed can be increased by forming the standard density pattern of the black toner outside the image area.

According to the eighth aspect, even when the small particle size toner is used, the standard density pattern of the black toner is formed on the intermediate transfer body, and the portion of the intermediate transfer body where the standard density pattern of the black toner is formed is applied. By detecting the pattern density of the standard density pattern as a layer, the reflection efficiency of the detection light on the surface of the pattern density detection part of the standard density pattern is improved, and it is possible to detect the change in the reflected light amount according to the toner amount of black toner. It is possible to provide a good image forming apparatus.

According to the ninth aspect, by detecting the pattern density of the standard density pattern with the coating layer having a color other than black, the reflection efficiency of the detection light on the surface of the pattern density detecting portion of the standard density pattern is further improved. However, the detection of the change in the reflected light amount according to the toner amount of the black toner becomes better.

According to the tenth aspect, the image forming speed can be increased by forming the standard density pattern of the black toner outside the image area.

According to the eleventh aspect, even when the small particle diameter toner is used, at least the standard density pattern of the black toner is formed on the intermediate transfer member, and the standard density pattern of the black toner of the intermediate transfer member is formed. A toner layer of a color different from the standard density pattern of black toner is provided between the intermediate transfer member and the standard density pattern of black toner, and the non-black toner layer is detected by detecting the pattern density of the standard density pattern of black toner. Since the detection light is reflected by the above, it is possible to provide an image forming apparatus in which the change in the reflected light amount according to the toner amount of black toner can be detected well.

According to the twelfth aspect, by making the intermediate transfer member black, the change in the reflected light amount according to the toner amount of the black toner can be further detected.

According to the thirteenth aspect, the pattern density of the standard density pattern of the black toner can be accurately detected, and the image density and the toner density can be accurately controlled.

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram of a color image forming apparatus according to an embodiment of an image forming apparatus according to the present invention.

FIG. 2 is a diagram showing a projected image of polymerized toner particles.

FIG. 3 is an enlarged view of a main part of the image forming unit of FIG. 1, showing a standard density pattern and an image density detecting unit for detecting the pattern density of the standard density pattern according to claim 1 or 2 of the present invention.

FIG. 4 is a diagram showing an image density detecting means.

FIG. 5 is a diagram showing a formation area of a standard density pattern.

FIG. 6 is an enlarged view of a main part of the image forming section in FIG. 1 showing a standard density pattern according to claim 3 or 4 of the present invention, an image density detecting means for detecting the pattern density of the standard density pattern, and a toner density detecting sensor. It is a figure.

FIG. 7 is an enlarged view of a main part of the image forming section of FIG. 1 showing a standard density pattern and an image density detecting means for detecting the image density of the standard density pattern according to claims 5 to 13 of the present invention.

FIG. 8 is an explanatory diagram of a surface state of an intermediate transfer member in a standard density pattern forming portion according to claim 5 or 6 of the present invention.

FIG. 9 is an explanatory diagram of a surface state of an intermediate transfer member of a standard density pattern forming portion according to claim 8 or 9 of the present invention.

FIG. 10 is an explanatory diagram of a method for forming a standard density pattern on an intermediate transfer member according to claim 11 or 12 of the present invention.

[Explanation of symbols]

10 photoconductor 11 Scorotron charger 12 Exposure optical system 13 Developer 13a Developing roller 14a transfer belt 14c Primary transfer roller 14g Secondary transfer roller 15 paper cassettes 16 Timing roller 17 Fixing device 19 Image forming body cleaning device 19a Image forming member cleaning blade 191 Intermediate Transfer Body Cleaning Device 191a Intermediate transfer member cleaning blade P recording paper PSa, PSb Photo sensor PTa, PTb, PTc standard pattern TD toner density detection sensor

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03G 15/16 G03G 9/08 361 (72) Inventor Hiroshi Akita 2970 Ishikawacho, Hachioji, Tokyo Konica Stock Company F term (reference) 2H005 AA21 EA05 2H027 DA09 DA10 DE10 EA06 EB04 EB06 EC03 EC06 2H030 AD01 AD03 BB23 BB36 BB38 BB42 BB63 2H200 GA23 GA45 GA47 GA50 GA51 GB12 HA12 JC03 JC09 JC12 JC13 LB04 MAC09 J16

Claims (13)

[Claims] 1. An image forming body, charging means for uniformly charging the surface of the image forming body, and imagewise exposing the surface of the image forming body charged by the charging means to form an electrostatic latent image on the image forming body. An image exposing unit for forming an image, and an electrostatic latent image formed on the image forming body have a volume average particle diameter of 3
Reversal developing means for developing with a small particle size toner of ˜7 μm to form a toner image on the image forming body; transfer means for transferring the toner image formed on the image forming body onto an intermediate transfer body; An image forming member cleaning unit that cleans the untransferred toner remaining on the forming member by an image forming member cleaning member that is in contact with the surface of the image forming member, and an untransferred toner remaining on the intermediate transfer member. In an image forming apparatus having an intermediate transfer member cleaning unit that cleans with an intermediate transfer member cleaning member that is in contact with the surface of the intermediate transfer member, the small particle size toners are toners of a plurality of colors and black toner, 1 standard density pattern is formed on the image forming body, and a second standard density pattern of a plurality of color toners on the image forming body is formed on the intermediate transfer body. And a pattern density of a first standard density pattern formed on the image forming body is detected by a first image density detecting unit that detects the first standard density pattern, and the intermediate transfer body is formed. An image forming apparatus, wherein a pattern density of a second standard density pattern formed on the upper side of the second standard density pattern is detected by a second image density detecting means for detecting the second standard density pattern. 2. The pattern density of the first standard density pattern is detected on the image forming body, the first standard density pattern is transferred onto an intermediate transfer body, and the intermediate transfer body cleaning means performs the transfer. The image forming apparatus according to claim 1, wherein the first standard density pattern is cleaned. 3. An image forming body, charging means for uniformly charging the surface of the image forming body, and imagewise exposing the surface of the image forming body charged by the charging means to form an electrostatic latent image on the image forming body. An image exposing unit for forming an image, and an electrostatic latent image formed on the image forming body have a volume average particle diameter of 3
An image having reversal developing means for developing with a toner having a small particle size of ˜7 μm to form a toner image on an image forming body, and transfer means for transferring the toner image formed on the image forming body onto an intermediate transfer body. In the forming apparatus, the small particle size toners are a plurality of colors of toner and a black toner, a standard density pattern of the plurality of colors of toner on the image forming body is formed on the intermediate transfer body, and the standard density pattern is formed on the intermediate transfer body. Image density control is performed by detecting the pattern density of the standard density patterns of a plurality of colors to be formed by the image density detection means for detecting the pattern density of the standard density pattern, and the black toner is image density controlled by the image density control means. An image forming apparatus characterized by performing. 4. The image density control means for the black toner comprises 2
The image forming apparatus according to claim 3, wherein the image forming apparatus is a toner concentration detection sensor that detects a toner concentration in the component developer. 5. An image forming body, charging means for uniformly charging the surface of the image forming body, and imagewise exposing the surface of the image forming body charged by the charging means to form an electrostatic latent image on the image forming body. An image exposing unit for forming an image, and an electrostatic latent image formed on the image forming body have a volume average particle diameter of 3
An image having reversal developing means for developing with a toner having a small particle size of ˜7 μm to form a toner image on an image forming body, and transfer means for transferring the toner image formed on the image forming body onto an intermediate transfer body. In the forming apparatus, the toner having the small particle size is black toner, and the standard density pattern of the black toner is formed on the intermediate transfer member. At least a portion where the standard density pattern is formed is a mirror surface, and the standard density pattern of the standard density pattern is formed. An image forming apparatus characterized by detecting pattern density. 6. When the volume average particle diameter of the toner forming the standard density pattern is r, the surface roughness of at least the mirror surface forming the standard density pattern of the intermediate transfer member is set to 0.05 r or less. The image forming apparatus according to claim 5, wherein the image forming apparatus is an image forming apparatus. 7. The image forming apparatus according to claim 5, wherein the position on the intermediate transfer body where the standard density pattern is formed is outside the image area. 8. An image forming body, charging means for uniformly charging the surface of the image forming body, and imagewise exposing the surface of the image forming body charged by the charging means to form an electrostatic latent image on the image forming body. An image exposing unit for forming an image, and an electrostatic latent image formed on the image forming body have a volume average particle diameter of 3
An image having reversal developing means for developing with a toner having a small particle size of ˜7 μm to form a toner image on an image forming body, and transfer means for transferring the toner image formed on the image forming body onto an intermediate transfer body. In the forming apparatus, the toner having the small particle diameter is black toner, and the standard density pattern of the black toner is formed on the intermediate transfer member. At least a portion forming the standard density pattern is a coating layer, and the standard density pattern is formed. An image forming apparatus, which detects the pattern density of the image. 9. The image forming apparatus according to claim 8, wherein the color of the coating layer is a color other than black. 10. The image forming apparatus according to claim 8, wherein the position on the intermediate transfer body where the standard density pattern is formed is outside the image area. 11. An image forming body, charging means for uniformly charging the surface of the image forming body, and imagewise exposing the surface of the image forming body charged by the charging means to form an electrostatic latent image on the image forming body. An image exposing unit for forming an image, and an electrostatic latent image formed on the image forming body have a volume average particle diameter of 3
An image having reversal developing means for developing with a toner having a small particle size of ˜7 μm to form a toner image on an image forming body, and transfer means for transferring the toner image formed on the image forming body onto an intermediate transfer body. In the forming apparatus, the small particle size toner is a toner of a plurality of colors and a black toner, and a standard density pattern of at least the black toner is formed on an intermediate transfer body, and the intermediate transfer body and the standard density pattern are formed. An image forming apparatus, characterized in that a toner layer of a color different from that of the standard density pattern is provided therebetween to detect the pattern density of the standard density pattern. 12. The image forming apparatus according to claim 11, wherein the intermediate transfer member is black. 13. The image forming apparatus uses a two-component developer, and detects a pattern density of a standard density pattern of black toner formed on the intermediate transfer member, and detects a standard density pattern of the black toner. 13. The image forming apparatus according to claim 11, wherein the toner density in the two-component developer is controlled by being detected by an image density detecting unit.