JP2002323786A - Toner and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of restraining the reverse transfer of toner from a transfer body such as an intermediate transfer belt to a latent image carrier such as a photoreceptor drum. SOLUTION: The toner whose non-electrostatic adhesive force is <=15 [nN] and whose cohesive degree is >=6[%] is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic latent image formed on a latent image carrier of an image forming apparatus such as a copying machine, a facsimile, a printer, etc., and develops the electrostatic latent image into a toner image. The present invention relates to a toner, an image forming method and an image forming apparatus using the same.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus for forming a composite image by sequentially superimposing a toner image developed on a latent image carrier such as a photosensitive drum onto a transfer body such as a transfer paper or an intermediate transfer body and contact-transferring the same. It has been known.

[0003]

In this type of image forming apparatus, the previously transferred toner image is reversely transferred from the transfer member to the latent image carrier in the subsequent contact transfer, thereby deteriorating the quality of the synthesized image. There is. The most typical example of an image forming apparatus for forming a composite image is an apparatus that forms a full-color image by superimposing black, yellow, magenta, and cyan toner images. The color tone reproducibility is deteriorated by the copying.

Japanese Patent Application Laid-Open No. Hei 9-319179 proposes a color image forming apparatus in which a toner image of each color is transferred first, so that the amount of adhered toner is increased. According to such a color image forming apparatus, disturbance of color tone due to reverse transfer can be suppressed by increasing the amount of toner adhered to a toner image in which the chance of reverse transfer increases.

However, in this color image forming apparatus, it is difficult to increase the running cost by increasing the wasteful amount of waste toner and to make it difficult to recycle the residual toner collected from the latent image carrier for the reasons described below. There is a problem that

That is, the color image forming apparatus includes a single type in which a plurality of developing means for each color are made to correspond to one latent image carrier, and a toner image of each color is sequentially formed on the latent image carrier. There is a tandem type in which a plurality of latent image carriers for each color are individually associated with developing means for a dedicated color.

In a single type color image forming apparatus,
Since the residual toner of each color is collected from the latent image carrier after the transfer step and mixed, the recycling of the residual toner is difficult. At present, a method of discarding the residual toner is adopted. Therefore, the amount of waste toner is increased by the amount of toner adhesion.

On the other hand, in a tandem type color image forming apparatus, basically, only a toner of a specific color is adhered to each latent image carrier, so that residual toner free of color mixture is removed from each latent image carrier. It can be collected and recycled. However, if the above-described reverse transfer occurs, color mixing occurs in the residual toner, making it difficult to recycle the toner. In the color image forming apparatus disclosed in the above publication, the amount of toner adhesion is increased on the assumption that reverse transfer occurs, so that color mixing of residual toner is inevitable. Therefore, it is difficult to recycle the residual toner.

The present invention has been made in view of the above background, and an object of the present invention is to provide a toner, an image forming method, and an image forming method capable of suppressing reverse transfer from a transfer member to a latent image carrier. It is to provide a device.

[0010]

According to one aspect of the present invention, an image forming apparatus to be used is specified, and an electrostatic latent image on a latent image carrier of the image forming apparatus is provided. A toner for developing the electrostatic latent image by adhering to the toner, the average value of non-electrostatic adhesion to the latent image carrier is 15 [nN / piece] or less, and the cohesion degree is 6 [% ] Or more.

In this toner, the reverse transfer from the transfer body to the latent image carrier can be favorably suppressed for the following reason. That is, the aggregate of toner constituting the toner image on the transfer body forms a plurality of toner layers stacked in multiple stages, and among these toner layers, the surface layer at the position directly in contact with the latent image carrier is formed. The toner mainly reverse-transfers. In a contact transfer area such as a transfer nip, a force as shown in FIG. 1A acts on the surface toner. In the figure, a toner T in a surface layer of a toner image sandwiched between a photosensitive drum 40 as a latent image carrier and an intermediate transfer belt 10 as a transfer body is caused by a transfer electric field formed therebetween. The electrostatic force A, the non-electrostatic adhesion B to the photosensitive drum 40, and the cohesion C in the toner aggregate act. Among these forces, the one that contributes to the reverse transfer of the toner is the non-electrostatic adhesion B. Therefore, “Non-electrostatic adhesion B <
If the condition of "electrostatic force A + cohesive force C" is satisfied, reverse transfer does not theoretically occur as shown in FIG.
On the other hand, if the condition “non-electrostatic adhesion B> electrostatic force A + cohesion C” is satisfied, reverse transfer occurs as shown in FIG. 1C. Of these three forces, the electrostatic force A depends on the transfer electric field strength of the image forming apparatus, while the non-electrostatic adhesion B and the cohesion C depend on the latent properties of the toner. Therefore, the present inventors evaluated the relationship among the non-electrostatic adhesion B, the degree of aggregation, and the reverse transfer rate for various toners. Then, the average value of the non-electrostatic adhesion B is 15 [nN /
It has been found that almost no toner having a reverse transfer rate such that the deterioration in image quality is visually recognized is small for toners having a particle size of less than or equal to or less than 6%. Therefore, the present toner can favorably suppress reverse transfer from the transfer body to the latent image carrier. The method of evaluating the relationship between the non-electrostatic adhesion B, the degree of aggregation, and the reverse transfer rate, which has been performed by the present inventors, will be described later in detail.

According to a second aspect of the present invention, an image forming apparatus to be used is designated, and the toner is used to adhere to an electrostatic latent image on a latent image carrier of the image forming apparatus and develop the electrostatic latent image. And the average value of the non-electrostatic adhesion to the latent image carrier [nN /
And a combination that exhibits the same value of cohesion as the minimum cohesion in the graph showing the relationship between cohesion and the degree of cohesion, or a combination corresponding to a downward trend curve portion of the graph with an increase in the average value. It is characterized by exhibiting the average value and the degree of aggregation.

In the toner, the reverse transfer from the transfer member to the latent image carrier can be satisfactorily suppressed for the following reason. That is, as can be seen from the above-described condition of “non-electrostatic adhesion B <electrostatic force A + cohesion C”, the smaller the non-electrostatic adhesion B is, the more difficult the reverse transfer is to occur. In addition, the higher the cohesion degree of the toner, the more difficult it is for reverse transfer to occur. According to the experiments of the present inventors, the relationship between the degree of aggregation of the toner and the non-electrostatic adhesion B is as shown in the graph of FIG. That is, first, the cohesion degree gradually decreases as the non-electrostatic adhesion B gradually increases from around zero, but after the non-electrostatic adhesion B reaches a predetermined value, the non-electrostatic adhesion B is reversed. The cohesion gradually increases as the electroadhesive force B increases. When the non-electrostatic adhesion B reaches this predetermined value, the cohesion degree becomes a minimum cohesion degree showing a minimum value. Now, in the process of gradually lowering the non-electrostatic adhesion B of the toner toward this predetermined value in order to suppress reverse transfer, a curve on the right side of the dashed-dotted line attached to the position of the predetermined value in the drawing. As can be seen from the portion, while the reverse transfer is suppressed by the decrease of the non-electrostatic adhesion B, the reverse transfer is promoted by the decrease of the cohesion. On the other hand, in the process of gradually lowering the non-electrostatic adhesion B of the toner from the predetermined value to near zero,
In addition to suppressing the reverse transfer by reducing the non-electrostatic adhesion B, the reverse transfer is also suppressed by increasing the degree of aggregation. As a result, in the curved portion on the left side of the dashed line in the drawing, the reverse transfer of the toner is favorably suppressed. Therefore, the present toner exhibits the same cohesion degree as the minimum cohesion degree, or cooperates with the average value in a combination corresponding to the downward trend curve portion of the above graph with an increase in the non-electrostatic adhesion. It is configured to demonstrate the degree.

According to a third aspect of the present invention, an image forming apparatus to be used is designated, and the toner is used for developing the electrostatic latent image by attaching to the electrostatic latent image on the latent image carrier of the image forming apparatus. There, or show the cohesion degree of the same value as the minimum cohesion degree in the graph showing the relationship between the coverage by the external additive and the cohesion degree,
Alternatively, the present invention is characterized in that the coverage and the cohesion degree are exhibited in a combination corresponding to a rising trend curve portion of the graph with an increase in the coverage.

In the toner, the reverse transfer from the transfer body to the latent image carrier can be satisfactorily suppressed for the following reason. That is, when the coverage of the toner with the external additive increases, the non-electrostatic adhesion B decreases. According to the experiments by the present inventors, the relationship between the degree of aggregation of the toner and the coverage by the external additive is as shown in the graph of FIG. That is, as in the graph shown in FIG. 2, the degree of agglomeration gradually decreases as the coverage gradually increases from around zero, but after the coverage reaches a predetermined value, the coverage is reversed. , The degree of aggregation gradually increases. When the coverage reaches this predetermined value, the cohesion becomes the minimum cohesion indicating the minimum value. By the way, in the process of gradually increasing the coverage toward this predetermined value in order to suppress the reverse transfer, as can be seen from the curve portion on the left side of the dashed line in the figure, the reverse is caused by the increase in the coverage. While suppressing copying, reverse transcription is promoted by a decrease in the degree of aggregation. On the other hand, in the process of gradually increasing the coverage from the one-dot chain line portion, in addition to suppressing the reverse transfer by increasing the coverage, the reverse transfer is also suppressed by increasing the degree of aggregation. As a result, the reverse transfer of the toner is favorably suppressed in the curved portion on the right side of the dashed line in the drawing. Therefore, the present toner exhibits the cohesion degree of the same value as the minimum agglomeration degree, or exhibits the coverage and the cohesion degree in a combination corresponding to the rising trend curve portion of the above graph with the increase in the coverage rate. It is configured to be.

In the image forming apparatus of the first, second and third aspects, "designation of an image forming apparatus to be used"
This is performed by specifying the name, product number, and the like of the image forming apparatus to be used in a toner container, a seal attached to the container, an instruction manual, and the like.

According to a fourth aspect of the present invention, there is provided the toner according to the first, second or third aspect, wherein the toner is produced by a polymerization method.

In this toner, the degree of circularity is higher than that of the toner manufactured only by the pulverization method, and the toner has a shape close to a true sphere. In such a toner, the non-electrostatic adhesion B to the latent image carrier is reduced by reducing the unevenness on the surface, so that the reverse transfer can be more favorably suppressed.

According to a fifth aspect of the present invention, there is provided the toner according to the first, second or third aspect, wherein the toner is manufactured by a pulverizing method.

In this toner, the production cost can be reduced as compared with the toner produced by the polymerization method.

According to a sixth aspect of the present invention, there is provided the toner according to the fifth aspect, wherein a spherical process is performed.

In this toner, since the circularity is increased by the spherical processing, the non-electrostatic adhesion B to the latent image carrier is reduced, and the reverse transfer can be suppressed more favorably.

According to a seventh aspect of the present invention, there is provided the first, second, third,
4. A toner according to 4, 5, or 6, wherein a lubricant having a lower coefficient of friction is dispersed in the base material.

In this toner, the frictional coefficient of the toner particles is reduced by a lubricant, so that deterioration due to friction is suppressed. Therefore, it is possible to suppress a decrease in image quality due to such deterioration.

An eighth aspect of the present invention is the toner according to the seventh aspect, wherein the lubricant has a softening temperature lower than that of the base material.

In this toner, the heating temperature of the heat fixing device of the image forming apparatus can be lowered by lowering the softening temperature of the toner particles by the lubricant.

The ninth aspect of the present invention is the first aspect of the present invention.
4, 5, 6, 7 or 8, wherein the half width of the distribution curve of the charge ratio (charge amount / particle size) is 2.2 [fC / 10
μm].

In this toner, since the half width of the distribution curve of the charge ratio is 2.2 [fC / 10 μm], the background smear caused by the uneven charge ratio between the individual toners can be favorably suppressed. .

According to a tenth aspect of the present invention, there is provided a latent image forming step of forming an electrostatic latent image on a latent image carrier, and a developing step of developing the electrostatic latent image on the latent image carrier into a toner image by attaching toner. A combination of the steps is performed a plurality of times, and further, a step of forming a composite transfer image by sequentially superimposing a plurality of toner images formed by these combinations from the latent image carrier onto the transfer body and contact-transferring the same is performed. In the image forming method, the toner according to any one of claims 1, 2, 3, 4, 5, 6, 7, 8, and 9 is used as the toner.

According to this image forming method,
By using the toner of 2, 3, 4, 5, 6, 7, 8 or 9, the transfer body on which the toner image has already been transferred is further brought into contact with the latent image carrier to perform superposition transfer. Reverse transfer of the toner can be favorably suppressed. Further, it is possible to suppress a decrease in image quality of the composite transfer image due to the reverse transfer.

According to the eleventh aspect of the present invention, there is provided a latent image carrier for carrying an electrostatic latent image, a latent image forming means for forming an electrostatic latent image on the latent image carrier, and a static image on the latent image carrier. Developing means for developing the electrostatic latent image into a toner image by attaching toner, and transfer means for sequentially superimposing the toner image developed on the latent image carrier on a transfer body and contact-transferring to form a composite transfer image An image forming apparatus comprising:
3, 4, 5, 6, 7, 8 or 9 is used.

In this image forming apparatus, "toner" refers to a type of toner designated by a manufacturer or a distributor of the apparatus. This designation is performed by, for example, describing the product name, product number, and standard of the usable toner in an instruction manual or a sticker of the apparatus, or by packing the toner with the apparatus and shipping the toner.

In this image forming apparatus,
By using the toner of 2, 3, 4, 5, 6, 7, 8 or 9, the reverse transfer of the toner which occurs when the toner image is superimposed and transferred from the latent image bearing member to the transfer member is favorably suppressed. Can be. Further, it is possible to suppress a decrease in image quality of the composite transfer image due to the reverse transfer.

According to a twelfth aspect of the present invention, in the image forming apparatus of the eleventh aspect, the developing means includes a plurality of developing means for developing the electrostatic latent images on the latent image carrier with toners of different colors. A latent image forming means for individually forming an electrostatic latent image for each color on the latent image carrier, and a full-color image formed by superimposing toner images of respective colors developed by these developing means. It is characterized by forming an image.

In this image forming apparatus, it is possible to suppress deterioration in color tone reproducibility of a full-color image due to reverse transfer of toner from a transfer member to a latent image carrier.

According to a thirteenth aspect of the present invention, in the image forming apparatus according to the twelfth aspect, the latent image carrier includes a plurality of latent image carriers respectively corresponding to a plurality of the developing means, The image forming means includes means for forming electrostatic latent images for different colors on the respective latent image carriers.

In this image forming apparatus, a full-color image is formed by a so-called tandem method using a plurality of latent image carriers for each color. With such a configuration, for the reason described below, the formation time of the full-color image can be shorter than that of a so-called single-type image forming apparatus that forms a full-color image using only one latent image carrier. That is, in the single type image forming apparatus, since only one latent image carrier is provided, it is necessary to repeat formation of the toner image and transfer to the transfer body for each color. On the other hand, in a tandem system such as the present image forming apparatus, it is not necessary to repeatedly form and transfer a toner image, and it is possible to form each color toner image almost simultaneously on a dedicated latent image carrier. It is possible to transfer the image while superimposing it on the transfer body. Therefore, the image forming time of a full-color image can be shorter than that of the single-type image forming apparatus.

According to a fourteenth aspect of the present invention, there is provided the image forming apparatus according to the thirteenth aspect, wherein the collecting means for individually collecting the toner remaining on each latent image carrier after the transfer, and the collected toner of each color are recycled. And recycling means for returning the developing means to the corresponding developing means.

In this image forming apparatus, by suppressing the reverse transfer of the toner from the transfer member to the latent image carrier, the color mixture of the residual toner on each latent image carrier is suppressed. Then, by recycling the residual toner with little color mixture, it is possible to suppress the deterioration of the image quality of the full-color image due to the use of the mixed toner.

[0040]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of a color laser copying machine (hereinafter simply referred to as a copying machine) will be described as an image forming apparatus to which the present invention is applied. First, a basic configuration of the copying machine will be described. FIG. 4 is a schematic configuration diagram showing the copying machine. In the figure, the copying machine includes an image forming unit 100, a paper feed table 200, a scanner unit 300, an automatic document feeder (hereinafter, referred to as an ADF) 4
00 and the like.

The image forming section 100 has an endless intermediate transfer belt 10 near its center. As shown in FIG. 5, the intermediate transfer belt 10 has an elastic layer 12 made of an elastic material such as fluororubber or acrylonitrile-butadiene copolymer rubber laminated on a base layer 11 made of a non-stretchable material such as fluororesin or canvas. Further, a coating layer 13 such as a fluorine-based resin is laminated thereon to impart smoothness to the front surface.

As shown in FIG. 4, the intermediate transfer belt 10 is endlessly moved clockwise in the figure while being wrapped around three support rollers 14, 15, and 16.

Among the three support rollers, the support roller 15 on the left side in the figure is disposed so as to sandwich the intermediate transfer belt 10 between the support roller 15 and the belt cleaning device 17. This belt cleaning device 17 is used for the intermediate transfer belt 10.
It plays a role of removing residual toner remaining on the front surface.

A tandem image forming section 20 is disposed above the intermediate transfer belt 10 in the drawing. The tandem image forming unit 20 moves the intermediate transfer belt 10 from the point at which it is stretched by the support roller 15 on the left side in FIG. The black (BK), cyan (C), magenta (M), and yellow (Y) image forming units 18B
K, 18Y, 18M, and 18C are sequentially contacted. More specifically, the photosensitive drums 40BK of these image forming units,
40Y, 40M, and 40C are sequentially contacted.

An exposure device 21 is disposed above the tandem image forming section 20 in the figure, and is configured to detect each of the photosensitive drums 40BK, which are latent image carriers, based on image information.
By exposing 40Y, 40M, and 40C, B
An electrostatic latent image for K, an electrostatic latent image for Y, an electrostatic latent image for M, and an electrostatic latent image for C are formed.

On the lower side of the intermediate transfer belt 10 in the figure,
A secondary transfer device 22 is provided. The secondary transfer device 22 includes two support rollers 23 and an endless secondary transfer belt 24 wound around these rollers. Of the two support rollers 23, the support roller 23 on the right side in FIG.
Interposes the secondary transfer belt 24 and the intermediate transfer belt 10 between the above-described support roller 16 that supports the intermediate transfer belt 10. Between the two belts sandwiched in this manner, a transfer sheet sent from a manual tray or a sheet feeding table described later is further sandwiched. Then, the toner image on the intermediate transfer belt 10 is secondarily transferred onto the transfer paper. The illustrated secondary transfer device 22 includes a secondary transfer bias applied to a support roller 23 on the right side in the figure and a nip of a secondary transfer nip formed by contact between the support roller 23 and the support roller 16. Although the secondary transfer is performed under the influence of pressure or the like, the secondary transfer may be performed using a transfer charger.

The transfer paper after the secondary transfer is a secondary transfer belt 2
4 is fed into the fixing device 25 with the endless movement. In the fixing device 25, a fixing nip is formed by contact with the heating belt unit 26 and the pressure roller, and the transfer paper conveyed while being sandwiched between the fixing nip and the transfer paper is heated by the action of the nip pressure. The toner image is fixed.

At the lower side of the secondary transfer device 22 in the figure, there is provided a reversing transport device 28 for reversing the transfer paper after passing through the fixing device 25 and re-transporting it to the secondary transfer nip. ing.

On the left side of the fixing device 25 in the figure,
A discharge roller pair 56 for discharging the transfer paper after passing through the outside of the apparatus is provided.

The fixing device 25 is provided with a switching claw 55 for switching the transfer path of the transfer sheet having passed through the fixing nip between a path to the discharge roller pair 56 and a path to the reverse transfer device 28. . When the transfer path is switched to the latter path by the switching claw 55, the transfer paper is turned over and then re-conveyed to the secondary transfer nip, and after the toner image is secondarily transferred to the opposite surface, the fixing is performed. Device 25
Established within. When the path is switched to the former path, the transfer sheet after the fixing process is stacked on a discharge tray 57 outside the apparatus via the discharge roller 56.

When copying is performed using this copying machine, first, whether the original is on the original platen 30 of the ADF 400
Alternatively, the scanner 300 disposed below the ADF 400
It is set on the contact glass 32 of the section. And
When a start switch (not shown) is pressed, ADF4
After the original set in 00 is conveyed onto the contact glass 32, the image is read by the scanner unit 300. Further, the image of the original set on the contact glass 32 is read by the scanner 300 at the same position.

When reading an original, the scanner section 300 first causes the first traveling body 33 and the second traveling body 34 to travel. Then, the light emitted from the light source of the first traveling body 33 is irradiated on the document surface, and the reflected light from the document surface is further reflected and received by the second traveling body 34. The second traveling body 34 further reflects the received light by a mirror, and sends the light to a reading sensor 36 through an imaging lens 35.

On the other hand, when the start switch is depressed, any one of the support rollers 14, 15, 16
One is rotated by a drive motor (not shown), and the intermediate transfer belt 10 is moved endlessly while the other two support rollers are driven to rotate. Further, the photosensitive drums 40BK, 40Y, 40M, and 40C of the respective image forming units are respectively driven to rotate, and are individually exposed by the exposure device 21 that is driven based on the image information sent from the scanner unit 300. , BK electrostatic latent image, Y electrostatic latent image, M electrostatic latent image, and C electrostatic latent image. These electrostatic latent images are developed by a BK developing device, an M developing device, and a C developing device, respectively, to obtain a BK toner image, a Y toner image, and a M toner image.
After the toner image and the C toner image are formed, they are sequentially superimposed on the intermediate transfer belt 10 and primary-transferred. By the primary transfer of the superposition, a full-color toner image is formed on the intermediate transfer belt 10.

When the start switch is depressed, the paper feed table 200 selectively rotates any one of the plurality of paper feed rollers 42 to feed a plurality of paper feeds provided in the paper bank 43. The transfer paper is sent out from any one of the paper cassettes 44. The transferred transfer paper is separated one by one by a separation roller 45 and then enters the paper feed path 46.
Then, the image forming unit 10 is transported by the plurality of transport rollers 47.
The sheet is guided to the sheet feeding path 48 within the pair of rollers 0 and stopped between the rollers of the pair of registration rollers 49.

However, when the manual feed tray 51 is selected as a paper feed unit to be used by an operation unit (not shown), the transfer paper on the manual feed tray 51 is supplied instead of the transfer paper in the paper feed table 200. The paper is fed by a paper roller 50 and is separated one by one by a separation roller 52. Then, the sheet enters the manual sheet feeding path 53 and is stopped by being sandwiched by the registration roller pair 49.

The registration roller pair 49 sends out the transfer paper sandwiched between the rollers toward the secondary transfer nip at a timing at which the transfer paper can be superimposed on the full-color toner image on the intermediate transfer belt 10. The transferred transfer paper is sent to the fixing device 25 after the full-color image is secondarily transferred at the secondary transfer nip.

For the registration roller pair 49, for example, a conductive rubber roller having a conductive NBR rubber layer having a diameter of 18 [mm] and a thickness of 1 [mm] is used, and a bias is applied to this. The electric resistance of the conductive NBR rubber layer is adjusted to about 10 ⁹ [Ωcm] by volume resistance, and the rubber layer of the roller that comes into contact with the toner image transfer target surface (hereinafter referred to as the front surface) of the transfer paper -850 on the surface
A bias of about [V] is applied. Also, a bias of about +200 [V] is applied to the surface of the rubber layer of the roller that comes into contact with the opposite surface (hereinafter referred to as the back surface) of the transfer paper. However, when paper powder transfer to the opposite surface is unlikely to occur, instead of applying the bias of about +200 [V],
A ground connection may be employed. Each bias may be an AC / DC superimposed bias instead of a DC bias. In some cases, the AC / DC superimposed bias can charge the transfer paper surface more uniformly.

By the application of such a bias, the front surface of the transfer sheet after passing through the registration roller 49 is charged to a negative polarity. Therefore, attention should be paid to the possibility that the secondary transfer condition may change depending on whether or not the bias is applied.

As shown in FIG. 6, the image forming unit 18BK includes a charging device 60BK, a developing device 61BK as a developing means, a primary transfer device 62BK, a drum cleaning device 63BK, and a photosensitive drum 40BK.
A static eliminator 64BK and the like are provided. Also, a toner recycling device (not shown) is provided.

The photosensitive drum 40BK is formed by forming a photosensitive layer of an organic photosensitive material exhibiting photosensitivity on the surface of a base tube made of aluminum or the like, but may be in the form of an endless belt. .

In the illustrated example, the members other than the primary transfer device 62BK are integrated as a process cartridge so that they can be collectively attached to and detached from the image forming unit 100, thereby improving the maintainability. Each member may be provided independently.

The charging device 60BK includes a charging roller,
It has a bias supply means for supplying a charging bias thereto, and applies a charging bias while contacting the photosensitive drum 40BK to uniformly charge the drum surface.

The developing device 61BK contains a two-component developer containing a magnetic carrier and a non-magnetic BK toner in a casing 70BK, and includes two screws 68BK, a toner density sensor 71BK, and a developing sleeve. 65BK, doctor blade 73BK and the like are provided. The two screws 68BK are disposed in a stirring section 66BK provided at a lower portion of the casing 70BK, and the two screws 68BK are partitioned by a partition plate 69BK. However, openings are provided near both ends of the partition plate 69BK. The two screws 68BK are
Along the axis, the two-component developer is conveyed in opposite directions, and is delivered to the other screw through the opening near the end. By this transfer, the two-component developer is circulated and transported. During this circulating transport,

A developing section 67BK is provided above the stirring section 66BK, and has a diameter of 18 [m].
m] of the cylindrical developing sleeve 65BK.
The developing sleeve 65BK is configured to exhibit a surface roughness of 10 to 30 [μm] in RZ by sandblasting surface treatment or surface treatment for forming a plurality of grooves having a depth of 1 to several [mm]. I have.

A roller-shaped magnet 72BK is fixed inside the cylindrical developing sleeve 65BK so as to be independent of the rotation of the sleeve. This magnet 72B
K is N1, S in the circumferential direction of the roller in order from the position facing a doctor blade described later in the sleeve rotation direction.
It has magnetic poles of 1, N2, S2, and S3.

The two-component developer conveyed by the screw on the right side of the figure is pumped up by the rotating sleeve surface under the influence of the magnet 72BK, forming a magnetic brush on the sleeve surface.

Above the developing sleeve 65BK, a doctor blade 73 is provided between the developing sleeve 65BK and the sleeve surface by 500 μm.
m]. When the magnetic brush on the developing sleeve 65BK passes through this gap as the sleeve rotates, the magnetic brush is cut off and its layer thickness is regulated. The cut-off two-component developer is supplied to the stirring unit 6.
Fall into 6BK. On the other hand, the two-component developer remaining on the sleeve surface causes the casing 70BK
And moves to the developing position, which is a position facing the photosensitive drum 40BK. At this development position,
A developing electric field is formed by the influence of a developing bias applied to the sleeve surface by a power supply (not shown). The BK toner in the two-component developer that has moved to the developing position is separated from the magnetic carrier under the influence of the developing electric field and adheres to the BK electrostatic latent image on the photosensitive drum 40BK. This adhesion develops the BK electrostatic latent image into a BK toner image.

The two-component developer that has contributed to the development as described above passes through the developing position, returns to the inside of the developing device via the opening of the casing 70BK, and receives the magnet 72
When the agitator 6 moves to the sleeve rotation position where it is hardly affected by the magnetic force of the BK, it moves away from the sleeve surface.
Fall to 6BK.

When the two-component developer that has contributed to the development returns and the toner concentration of the two-component developer in the agitating section 66BK decreases to a predetermined value, the toner concentration sensor 71BK
Is detected by Then, BK toner is supplied into the stirring section 66BK from outside the apparatus by a toner supply device (not shown).

The diameter of the developing sleeve 65BK is set to 18 [mm], and while the photosensitive drum 40BK having a diameter of 50 [mm] rotates at a linear speed of 200 [mm / S], the surface thereof is exposed to light. At the developing position, the photosensitive drum is rotated at a linear speed of 240 [mm / S] so as to move in the forward direction with respect to the drum surface.

The toner charge amount in the two-component developer on the developing sleeve 65BK is approximately 10 to 30 [-μC /
g].

The photosensitive drum 40BK and the developing sleeve 65
The value of the developing gap GP, which is the gap with the BK, is 0.
It can be set in the range of 4 to 0.8 [mm], and the development efficiency can be improved by minimizing the development gap GP.

The thickness of the photosensitive layer of the photosensitive drum 40BK is 30 [μm]. The beam spot of the exposure apparatus has a diameter of 50 × 60 [μm] and a light amount of 0.47 [mW]. Also, the photosensitive drum 40BK
, The exposure portion potential VL, and the developing bias are 0 to -700 [V], -120 [V], and -47, respectively.
It becomes 0 V, and development is performed at a development potential of 350 [V].

Although the developing device 61BK using two-component developer is provided in the illustrated apparatus, a developing device using only toner may be provided.

The above-mentioned primary transfer device 62BK holds the intermediate transfer belt 10 between the primary transfer device 62BK and the photosensitive drum 40BK.
A primary transfer roller for forming a secondary transfer nip and a power supply (not shown) for supplying a primary transfer bias to the primary transfer roller are provided. Instead of this primary transfer roller, an intermediate transfer belt 1
A corona charger for providing a charge may be provided on the back surface of the zero.

The drum cleaning device 63BK, which is a collecting means, has a cleaning blade 75B made of polyurethane rubber, the leading end of which contacts the photosensitive drum 40BK.
K, a conductive fur brush 76BK that rotates while contacting the drum. Also, a metal electric field roller 77BK for applying a cleaning bias to the fur brush 76BK while rotating, a scraper 78BK for contacting the tip thereof, a collecting screw 79BK for conveying the toner collected by cleaning, and the like are provided.

The fur brush 76BK rotates in the counter direction while contacting the photosensitive drum 40,
Remove the residual toner on the drum. The removed residual toner is supplied to the fur brush 76B with the bias supplied.
K is removed from the brush by the electric field roller 77BK rotating in the counter direction while contacting the K.
It is collected by a scraper 78BK abutting on the electric field roller 77BK.

The collected toner thus collected is
After being conveyed by the collection screw 79BK in the depth direction in the figure, the toner is returned into the developing device 61BK by a toner recycling device described later.

The static eliminator 64 includes a static elimination lamp and the like, and eliminates the charge on the surface of the photosensitive drum 40BK after the transfer process.

Although the image forming unit 18BK for forming a BK toner image among the four image forming units of the tandem image forming section 20 has been described in detail, the other image forming units 18Y, 18M and 18C are formed. The configuration is almost the same except that the color of the toner image and the toner to be used is different, and the description is omitted.

FIG. 7 is an enlarged configuration diagram showing a main part of the image forming unit 100. As shown in the drawing, the tandem image forming unit 20 controls the image forming unit to transfer the BK toner image, the Y toner image, the M toner image, and the C toner image onto the intermediate transfer belt 10 in a superimposed manner. 18BK, 18Y, 18M, 18C from the upstream side in the moving direction of
It is located in the order.

FIG. 8 is a perspective view showing a main part of the toner recycling device of the image forming unit 18BK together with the collecting screw 79BK of the drum cleaning unit 63BK. In the figure, the above-mentioned collection screw 79
The BK is provided at one end with a roller portion 82BK having two projecting pins 81BK. The transport belt 83BK of the toner recycling device 81 is
K and the roller portion of the rotation support member 86,
It is moved endlessly as follows. That is, the collection screw 7 has a plurality of long holes which are located at substantially the center of the belt width and are arranged at a predetermined pitch in the belt circumferential direction.
9 roller portion 82BK is provided with a protruding pin 81 in the belt loop.
By rotating the BK while engaging it with this elongated hole, the BK is moved endlessly. On the outer peripheral surface of the conveyor belt 83BK,
A plurality of blade members 85BK arranged at a predetermined pitch are protruded.

FIG. 9 is an exploded perspective view showing a BK process cartridge in which the photosensitive drum 40BK and the like are integrated. As shown, the toner recycling device 80BK
The toner conveying path 88BK is provided at a side position of the BK process cartridge, and communicates with the stirring section of the developing device 61. The rotation supporting member 86 of the toner recycling device 80BK is rotatably fixed so as to straddle the collection conveyance path, and the conveyance belt (83BK) (not shown) that moves endlessly while being supported by the collection conveyance path is accommodated in the collection conveyance path. Is done.

When the collection screw 79BK of the drum cleaning device 63BK is rotated by external drive transmission, the transport belt (83BK) (not shown) of the toner recycling device 80 moves endlessly in conjunction with the rotation. The collected toner collected by the collection screw 79BK falls from the end of the screw into the collection conveyance path of the toner recycle 80BK, and a plurality of blade members of the conveyance belt remove the collected toner in the collection conveyance path 88BK from the stirring unit of the developing device 61BK. Return to

The magnetic carrier in the two-component developer has a core made of metal or resin and a magnetic material such as ferrite, and the surface thereof is coated with a surface layer made of silicon resin or the like. The particle size is preferably in the range of 20 to 50 [μm], and the electrical resistance is 10 ⁴ to 10 ^{4 in} terms of dynamic resistance.
The range of 10 ⁶ [Ω] is optimal. However, this electric resistance is a diameter of 20 [mm] including a magnet and a rotation speed of 600 mm.
An electrode having a length of 65 [mm] and a width of [1 mm] is opposed to a magnetic carrier carried on a sleeve of [rpm] with a gap of 0.9 [mm], and a withstand voltage upper limit level (for a high-resistance silicon-coated carrier). It is a measured value when a voltage of 400 V or several V for an iron powder carrier is applied.

The toner in the two-component developer is obtained by mixing a charge controlling agent (CCA) and a coloring agent with a mother resin such as polyester, polyol, and styrene acrylic, and surrounding the material such as silica and titanium oxide. By being added, its charging characteristics and fluidity are adjusted. Generally, an external additive having a particle size in the range of 0.1 to 1.5 [μm] is used. Examples of the coloring agent include carbon black, phthalocyanine blue, quinacridone, carmine and the like. The charging polarity of the toner is the negative electrode name in this copying machine. The range of the volume average particle size of the toner is as follows.
The thickness is preferably 3 to 12 [μm], and is 6 [μm] in the present copying machine, and can sufficiently cope with a high-resolution image of 1200 [dpi] or more.

Next, the characteristic structure of the copying machine will be described. The present inventors have proposed various types of toners.
Non-Electrostatic Attachment (NEF) between Photoconductor Drum 40 (BK, Y, M, C) and Toner, Cohesion, and Intermediate Transfer Belt 1
The relationship between 0 and the reverse transfer rate of the toner to the photosensitive drum 40 was evaluated.

The evaluation method is as described below. That is, for evaluation, the non-electrostatic adhesion between the toner and the photosensitive drum 40 must be measured. As a method of measuring the adhesive force of the powder, a method of estimating the force required to separate the powder attached to a member from the member is generally used. Further, as a method of separating powder from a member, a method using centrifugal force, vibration, impact, air pressure, electric field, magnetic field, etc. is known, but a method using centrifugal force is relatively easy to quantify. And the measurement accuracy is high. Therefore, the present inventors use the centrifugal force to make the toner and the photosensitive drum 40
And a method of measuring the non-electrostatic adhesion to the substrate.

FIG. 10 is a conceptual diagram illustrating this method. First, an organic photoreceptor layer is formed on a polymer film on which aluminum has been vapor-deposited, and this film is attached to an aluminum substrate (measurement substrate). Then, an uncharged toner is dispersed and adhered on the organic photoconductor layer. A receiving substrate for receiving toner separated from the organic photoreceptor layer by centrifugal force, a spacer separating the measuring substrate and the receiving substrate, and a measuring substrate are placed in an aluminum holder, and this holder is mounted on a rotor of the centrifugal separator. set. As a centrifugal separator, an ultracentrifuge CP100α manufactured by Hitachi Koki Co., Ltd. (maximum rotational speed = 100000)
rpm, maximum centrifugal acceleration = 800000 G).
When the rotor is rotated, centrifugal force acts on the toner, and when the centrifugal force exceeds the non-electrostatic adhesion between the toner and the organic photoconductor layer, the toner separates from the organic photoconductor layer and is directed toward the receiving substrate. To fly. The separation test using such a centrifugal separator is repeatedly performed under a plurality of rotor rotation speed conditions, and the particle diameter Dt of the toner adhered to the receiving substrate in the separation test performed at different rotation speeds is determined by using an optical microscope and an image processing device. It measured using. Then, to determine the centrifugal force F _j by substituting the particle size Dt of the number 1 of the conditional expression below. In this conditional expression, f _j , ρt, and r indicate the rotation speed, the true specific gravity of the toner, and the distance from the rotation center of the rotor to the toner adhering surface, respectively.

(Equation 1)

The adhesive force between the toner and the organic photoreceptor layer is smaller than the centrifugal force F _j at the rotation speed at which the toner separation occurs, and is smaller than the centrifugal force F _{j-1 at the} rotation speed one step lower than this rotation speed. Therefore, the average value of _Fj and _Fj-1 was defined as the non-electrostatic adhesion.

The degree of aggregation of the toner was measured using a powder tester manufactured by Hosokawa Micron Corporation.

When an image is formed by the copying machine using each toner, the BK toner image primarily transferred from the BK photosensitive drum 40BK to the intermediate transfer belt 10 is transferred to the next Y photosensitive drum 40Y. The rate of reverse transfer was measured to determine the reverse transfer rate R.

FIG. 11 shows the result. In the figure, the toner having the cross point between the non-electrostatic adhesion and the cohesion degree indicated by a cross has a reverse transfer rate R of more than 4 [%], and this value indicates the color of the recycled toner due to the mixing caused by the reverse transfer. This is the level at which the change can be visually recognized. The reverse transfer rate R of the toner indicated by the symbol “と な り” is in the range of “2% <R ≦ 4%”. In this range, the original toner and the mixed toner are carefully compared, so that the mixed toner is finally noticed. . The reverse transfer rate R of the toner indicated by the mark “と な り” is 2% or less, and almost no mixed food is visually recognized.

Referring to FIG. 11, it can be seen that reverse transfer hardly occurs when the toner has a non-electrostatic adhesion of 15 [nN] or less and a cohesion degree of 6 [%] or more.

Therefore, in the copying machine of the first embodiment, a full-color image is formed using a toner having a non-electrostatic adhesion of 15 [nN] or less and a cohesion degree of 6 [%] or more. ing. Therefore, the reverse transfer of the toner from the intermediate transfer belt 10 to the photosensitive drum 40 can be suppressed, and the color tone change of the color image due to this can be suppressed. Further, it is possible to suppress a change in color tone due to mixing of the recycled toner.

Examples of the method for producing the toner used in the present copying machine include a pulverization method and a polymerization method. When the pulverization method is employed, the cost is lower than that of the polymerization method, but the sphericity of the toner is lower than that of the polymerization method. When the sphericity is low, the non-electrostatic adhesion tends to increase due to, for example, fine irregularities on the toner surface catching on the drum surface. on the other hand,
When the polymerization method is employed, the sphericity of the toner is higher than that of the pulverization method, but the production cost is considerably higher. Therefore, it is preferable to subject the toner produced by the pulverization method to a spherical treatment by a wear method or the like. In such a process, a toner having a sphericity equivalent to that at a lower cost than the polymerization method can be produced.

It is desirable to use a toner in which a lubricant such as a wax is dispersed in a base material by kneading or the like. By reducing the coefficient of friction of the toner,
This is because deterioration due to repeated friction with a cleaning blade, a magnetic carrier, or the like can be suppressed. Further, it is more preferable to use a substance having a lower softening temperature than the base material as the lubricant. This is because it is possible to lower the softening temperature of the entire toner and lower the temperature setting of the fixing device. Examples of such a lubricant include carnauba wax, which is a natural material, and polypropylene, which is a synthetic material.
These lubricants are present alone without ever reacting with the parent material.

The present inventors conducted a time-dependent quality check test based on the presence / absence of a lubricant. As a result, in the case of a toner without a lubricant, an increase in cohesion due to deterioration was observed after 190 k sheets of printout. The image quality was degraded due to the reduced ability. On the other hand, 3% by weight of carnauba wax
With the contained toner, image quality could be maintained without deterioration until 250 [K sheets] printout.

If the quality of each toner varies, the developing capability varies and the image quality becomes unstable. In particular, variations in the charging ability greatly affect the developing ability, and too much variation will cause background contamination. Therefore, the present inventors, by the method described below,
The relationship between the distribution of the charge ratio of the toner and the background stain was examined.

That is, the particle size of the toner on the developing sleeve 65 and the distribution of the charge ratio were examined. In order to examine the charge ratio, the particle size and charge amount of the toner must be measured. E-SPA manufactured by Hosokawa Micron Corporation was used for measurement.
RT ANALYZER was used. This E-SPAR
T ANALYZER measures the particle diameter and charge amount of each toner by blowing the air on the toner on the developing sleeve 65 by blowing it and capturing the movement in the electric field. 3000 toners were randomly extracted from the toner powder, their charge rates (charge amount q / particle diameter d) were determined, and their distribution was examined.

As the toner used for sampling,
A dry toner containing the modified polyester at least as a toner binder or a toner produced by a polymerization method is suitable. In this case, the former toner having a shape factor SF = 95 [%] was used.

First, when the particle size and the charge distribution of the toner on the developing sleeve 65 were measured initially, as shown in FIG. 12, the distribution curve of the charge became sharp, and the half width was 1. It was 1 [fC / 10 μm].

Here, the smaller the half width of the distribution curve, the more uniform the charge ratio among the toners, and hence the more stable the developing ability and the image quality. Conversely, as the half width increases, the variation in the charge ratio among the toners increases, and the developing ability and image quality become unstable. Then, when a low charge rate toner having a value equal to or less than a predetermined value appears, background stain is likely to occur.

The half width of the recycled toner was determined in the same manner. As a result, it was 1.7 [fC / 10 μm]. Further, when the half width after recycling of the pulverized toner not based on the polymerization method is measured, it is 2.7 [fC / 1
0 μm].

FIG. 13 shows the relationship between the half width of the charge distribution curve of the toner and the background contamination. As shown in the figure, when the half width exceeds 2.2 [fC / 10 μm], the undetectable limit value of background contamination exceeds 0.08 (the difference in reflection density with respect to untransferred paper is measured as Δ image ID). You can see that. Therefore, as a toner, the half width of the charge distribution curve is 2.2.
It is desirable to use the following:

Next, a copying machine according to a second embodiment of the present invention will be described. Note that the basic configuration of the copying machine is the same as that of the first embodiment, and a description thereof will be omitted.

FIG. 14 is a graph showing the relationship between the non-electrostatic adhesion between the toner and the photosensitive drum 40 and the cohesion of the toner. The non-electrostatic adhesion and the degree of aggregation were measured by the same method as in the first embodiment.

In the graph of FIG. 14, the characteristics A, B,
Reverse rotation of the toner image transferred from the BK photosensitive drum 40BK to the Y photosensitive drum 40Y in the toner image transferred to the intermediate transfer belt 10 using eight kinds of toners indicating C, D, E, F, G and H. I evaluated the shooting ratio R. These toners have various characteristics by changing the amount of the external additive added to the same toner particles. Table 1 below shows the relationship between the type of toner and the reverse transfer rate R. In the table, the toners marked with “x” have a reverse transfer rate R of more than 4 [%].
The toner indicated by the mark has a reverse transfer rate R in a range of “2% <R ≦ 4%”, and the toner indicated by a mark has a reverse transfer rate R of 2%.
[%] Or less. Further, the toner having the characteristic D shown in FIG. 14 exhibits the minimum aggregation degree in the graph.

[Table 1]

Referring to FIG. 14 and Table 1, in the graph of FIG. 14, the toners of the characteristics D, C, B, and A on the left side of the toner of the characteristic D exhibiting the minimum cohesion degree are in the initial state.
It can be seen that reverse transfer is favorably suppressed irrespective of whether 1000 sheets have been printed out. In the initial state, the toner of the characteristic E slightly to the right of the characteristic D suppresses the reverse transfer, but the reverse transfer rate R increases after printing out 1000 sheets. This is probably because the external additive buried due to the deterioration of the toner over time, and the non-electrostatic adhesion of the toner increased. Therefore, in this copying machine,
A full-color image is formed by using the toner having the characteristic D or the characteristic on the left side of the graph in FIG.

Although the tandem type color image forming apparatus has been described above, the present invention is also applicable to a single type color image forming apparatus and a monochromatic image forming apparatus.

[0111]

The first, second, third, fourth, fifth, sixth, seventh and eighth aspects of the present invention are described below.
According to the ninth aspect, there is an excellent effect that reverse transfer from the transfer body to the latent image carrier can be favorably suppressed.

In particular, according to the fourth aspect of the invention, the non-electrostatic adhesion B of the toner to the latent image carrier is reduced and the reverse transfer is favorably suppressed as compared with the case where the toner is manufactured only by the pulverization method. There is an excellent effect that you can.

According to the invention of the fifth or sixth aspect, there is an excellent effect that the production cost of the toner can be suppressed as compared with the case where the toner is produced by a polymerization method.

In particular, according to the invention of claim 6, by increasing the circularity of the toner by spherical processing, the non-electrostatic adhesion B of the toner to the latent image bearing member is reduced, and the reverse transfer is improved. There is an excellent effect that it can be suppressed well.

Further, in particular, according to the invention of claim 7 or 8, there is an excellent effect that deterioration of image quality due to toner deterioration due to friction can be suppressed.

Further, in particular, according to the invention of claim 8, there is an excellent effect that the heating temperature of the heat fixing device of the image forming apparatus can be lowered by lowering the softening temperature of the toner particles by the lubricant.

Further, according to the ninth aspect of the present invention, there is an excellent effect that background contamination due to unevenness in the charge ratio between the individual toners can be favorably suppressed.

According to the tenth aspect of the present invention, it is possible to satisfactorily suppress the reverse transfer of the toner when the transfer member on which the toner image has already been transferred is further brought into contact with the latent image carrier to perform the superposition transfer. There is an excellent effect that it can be done. Further, there is an excellent effect that the image quality of the combined transfer image due to the reverse transfer can be suppressed.

According to the eleventh, twelfth, thirteenth and thirteenth aspects of the present invention, the reverse transfer of the toner, which occurs when the toner image is superimposed and transferred from the latent image bearing member to the transfer member, can be excellently suppressed. Has an effect. Further, there is an excellent effect that the image quality of the combined transfer image due to the reverse transfer can be suppressed.

In particular, according to the twelfth, thirteenth, and fourteenth aspects of the invention, there is provided an excellent effect that deterioration in color tone reproducibility of a full-color image due to reverse transfer of toner from a transfer member to a latent image carrier can be suppressed. is there.

Further, in the image forming apparatus according to the present invention, the image forming apparatus of the present invention is more preferable than the single type image forming apparatus.
There is an excellent effect that the image forming time of a full-color image can be shortened.

In particular, according to the fourteenth aspect of the invention, there is an excellent effect that it is possible to suppress the deterioration of the image quality of a full-color image due to the use of the mixed toner.

[Brief description of the drawings]

FIG. 1A is a schematic diagram illustrating a force acting on a toner sandwiched between transfer nips. (B) is a schematic diagram for explaining a force relationship in which reverse transfer does not occur. (C) is a schematic diagram illustrating a force relationship in which reverse transcription occurs.

FIG. 2 is a graph showing the relationship between the degree of aggregation of toner and the non-electrostatic adhesion between toner and a latent image carrier.

FIG. 3 is a graph showing the relationship between the degree of aggregation of the toner and the coverage of the toner with an external additive.

FIG. 4 is a schematic configuration diagram showing a copying machine according to the first embodiment.

FIG. 5 is an enlarged sectional view showing an intermediate transfer belt of the copying machine.

FIG. 6 is a sectional view showing an image forming unit for Bk of the copying machine.

FIG. 7 is an enlarged configuration diagram illustrating a main part of an image forming unit of the copying machine.

FIG. 8 is a perspective view showing a main part of a toner recycling apparatus in the image forming unit together with a collecting screw of a drum cleaning unit.

FIG. 9 is an exploded perspective view showing a BK process cartridge of the copying machine.

FIG. 10 is a conceptual diagram illustrating a method for measuring non-electrostatic adhesion of toner.

FIG. 11 is a diagram illustrating a relationship among a non-electrostatic adhesion force, a cohesion degree, and a reverse transfer rate of toner.

FIG. 12 is a graph showing a charge distribution curve of a toner.

FIG. 13 is a graph showing a relationship between a half width of the charge distribution curve and background contamination.

FIG. 14 shows a non-electrostatic adhesive force between a toner and a photosensitive drum,
4 is a graph showing a relationship with the degree of aggregation of toner. 4 is a graph showing the relationship between the non-electrostatic adhesion between the toner and the photosensitive drum 40 and the cohesion of the toner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Intermediate transfer belt 11 Base layer 12 Elastic layer 13 Coat layer 14, 15, 16 Support roller 17 Belt cleaning device 18 Image forming unit 20 Tandem image forming part 21 Exposure device 22 Secondary transfer device 23 Support roller 24 Secondary transfer belt 25 Fixing device 26 Heating belt unit 28 Reverse transport device 30 Document table 32 Contact glass 33, 34 Carrier 35 Imaging lens 36 Sensor 40 Photoconductor drum 42 Feed roller 43 Paper bank 44 Paper cassette 45 Separation roller 46 Feed path 47 Transport roller 48 Paper feed path 49 Registration roller pair 50 Paper feed roller 51 Tray 52 Separation roller 53 Paper feed path 55 Switching claw 56 Discharge roller pair 57 Discharge tray 60 Charging device 61 Developing device 62 Primary transfer device 63 Drum cleaning device 4 Static eliminator 65 Developing sleeve 66 Stirring unit 67 Developing unit 68 Screw 69 Partition plate 70 Casing 72 Magnet 73 Doctor blade 75 Cleaning blade 76 Fur brush 77 Electric field roller 78 Scraper 79 Recovery screw 80 Toner recycling device 81 Projection pin 82 Roller unit 83 Conveyance Belt 85 Blade member 86 Rotation support member 88 Toner transport path 100 Image forming unit 200 Feed table 300 Scanner

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 15/01 G03G 15/01 114A 15/08 507L 114 507D 15/08 507 21/00 326 21/10 9 / 08 384 381 361 (72) Inventor Sadayuki Iwai 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Masafumi Kamonaga 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Inside Ricoh (72) Fumito Masuchibuchi 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Keiichi Seya 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72 Inventor Masako Yoshii 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Naofumi Shoji 1, Nakamagome, Ota-ku, Tokyo No. 3-6 Ricoh F-term in Ricoh Company (reference) 2H005 AA06 AA08 AA15 AA21 AB04 AB06 AB09 DA07 EA01 EA03 EA05 EA10 2H030 AB02 AD01 AD03 BB23 BB42 2H077 AA37 AC02 AC16 AD06 AD13 AD18 DB14 DB15 EA03 GA13 HD02 GA02 KG07 KG08 KH01 KH02 KH17 KJ02

Claims (14)

[Claims] An image forming apparatus to be used is designated,
A toner that adheres to the electrostatic latent image on the latent image carrier of the image forming apparatus and develops the electrostatic latent image, and has an average non-electrostatic adhesion to the latent image carrier of 15 [ nN / piece] or less, and the degree of aggregation is 6% or more. 2. An image forming apparatus to be used is designated,
A toner that adheres to the electrostatic latent image on the latent image carrier of the image forming apparatus and develops the electrostatic latent image, and is an average value of non-electrostatic adhesion to the latent image carrier [nN / And a combination that exhibits the same value of cohesion as the minimum cohesion in the graph showing the relationship between cohesion and the degree of cohesion, or a combination corresponding to the downward trend curve portion of the graph with an increase in the average value. A toner characterized by exhibiting the average value and the degree of aggregation. 3. An image forming apparatus to be used is designated.
A toner that adheres to the electrostatic latent image on the latent image carrier of the image forming apparatus and develops the electrostatic latent image, and has a minimum value in a graph showing the relationship between the coverage by an external additive and the degree of aggregation. Either exhibiting the same cohesion degree as the cohesion degree, or exhibiting the coverage and the cohesion degree in a combination corresponding to the rising trend curve portion of the graph with the increase of the coverage rate. Toner. 4. A toner according to claim 1, wherein the toner is produced by a polymerization method. 5. The toner according to claim 1, wherein the toner is manufactured by a pulverization method. 6. The toner according to claim 5, wherein the spherical processing is performed. 7. The toner according to claim 1, wherein a lubricant having a lower coefficient of friction is dispersed in the base material. 8. The toner according to claim 7, wherein the lubricant has a softening temperature lower than that of the base material. 9. The method of claim 1, 2, 3, 4, 5, 6, 7 or 8.
Wherein the half width of a distribution curve of charge ratio (charge amount / particle size) is 2.2 [fC / 10 μm]. 10. A combination of a latent image forming step of forming an electrostatic latent image on a latent image carrier and a developing step of developing the electrostatic latent image on the latent image carrier into a toner image by attaching toner. An image forming method for performing a plurality of times, and further performing a step of forming a composite transfer image by sequentially superimposing a plurality of toner images formed by the combination onto the transfer body from the latent image carrier to form a composite transfer image, 10. An image forming method using the toner according to claim 1, 2, 3, 4, 5, 6, 7, 8, or 9 as the toner. 11. A latent image carrier for carrying an electrostatic latent image, a latent image forming means for forming an electrostatic latent image on the latent image carrier, and a toner for transferring the electrostatic latent image on the latent image carrier to a toner. Image forming apparatus comprising: developing means for developing a toner image by adhesion of toner; and transfer means for sequentially superimposing a toner image developed on the latent image carrier on a transfer body and contact-transferring to form a composite transfer image. Wherein the toner is as described in claim 1, 2, 3, 4, 5, 6,
An image forming apparatus using the toner of 7, 8, or 9. 12. An image forming apparatus according to claim 11, further comprising a plurality of developing means for developing the electrostatic latent images on said latent image carrier with toners of different colors, respectively, as said developing means. The latent image forming means includes means for individually forming an electrostatic latent image for each color on the latent image carrier, and forming a full-color image formed by superimposing toner images of each color developed by these developing means. An image forming apparatus comprising: 13. An image forming apparatus according to claim 12, wherein said latent image carrier comprises a plurality of latent image carriers corresponding to a plurality of said developing means, respectively. An image forming apparatus comprising: a latent image carrier that forms electrostatic latent images for different colors. 14. An image forming apparatus according to claim 13, wherein said collecting means individually collects toner remaining on each latent image carrier after transfer, and said collecting means respectively correspond to recycle the collected toner of each color. An image forming apparatus, comprising: a recycling unit for returning to a developing unit.