JP2000019858A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of preventing the vermiculated image from being formed, even in the case of applying lubricant on at least, one of the image carrier surface or an intermediate transfer body surface. SOLUTION: This image forming device is constituted so that coefficient of static friction on the respective surface of a photoreceptor belt 1 and the intermediate transfer belt 10 in an actually using state satisfies the next relation, (coefficient of static friction on intermediate belt 10 surface)(coefficient of static friction on photoreceptor belt 1 surface)>-0.1. In such a manner, since toner is made possible to be easily transferred from the photoreceptor belt 1 surface to the intermediate transfer belt 10 surface, or the toner being transferred on the intermediate transfer belt 10 surface becomes to be hardly transferred on the photoreceptor belt 1 inversely, the vermiculated image can be prevented from being formed. In the actual using state of the image forming, since the lubricant is made possible to be applied based on the measurement result of the coefficient of static friction, so as to always satisfies the relation shown by the above inequality, the generation of the vermiculated image can be prevented from being formed with time.

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 such as a copying machine, a facsimile or a printer, and more particularly, to a toner image formed on an image carrier, which is primary-transferred onto an intermediate transfer member. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus that performs secondary transfer of an image onto a transfer material.

[0002]

2. Description of the Related Art Conventionally, a plurality of visible color developed images sequentially formed on an image carrier are sequentially superimposed on an endlessly moving intermediate transfer body and primary-transferred, and a primary transfer image (toner An image forming apparatus of an intermediate transfer system for performing secondary transfer of an image) collectively to a transfer material is known. In recent years, an image forming apparatus using this intermediate transfer method is advantageous in terms of miniaturization and less restrictions on the type of transfer material onto which a visible image is finally transferred. They tend to be used as devices.

In such an image forming apparatus, due to local transfer omission during the primary transfer and the secondary transfer of a toner image constituting a color developed image, a final image medium, such as transfer paper, is removed. In the image on the transfer material, a so-called insect-like portion where no toner is locally transferred may occur. FIG. 2 shows an example of such an insect-like image.
In the case of a worm-like image, in the case of a solid image, as shown by the symbol w in the drawing, transfer omission occurs with a certain area. In the case of a line image, transfer omission occurs so that the line is interrupted. Such an abnormal image is likely to occur when a four-color full-color image is formed. This is because, in addition to the thickening of the toner layer, the primary transfer is repeated up to four times. This is due to the strong generation of force (a force other than electrostatic force such as van der Waals force). Further, in the process of repeatedly executing the image forming process, a filming phenomenon occurs in which the toner adheres to the surface of the intermediate transfer body in a film form, and the adhesion between the surface of the intermediate transfer body and the toner increases. Conceivable.

Therefore, as a technique for avoiding the occurrence of such an insect-like image, a lubricant is applied to the surface of the image carrier and the intermediate transfer member to reduce the adhesive force with the toner, or the adhesive force of the toner itself. Technologies such as reducing the amount of methane with an external additive have already been put to practical use on market machines.

In Japanese Patent Application Laid-Open No. Hei 8-21755, the transferability is improved and the bug-like abnormality is improved by adjusting the relative balance between the toner adhesion of the image carrier and the toner adhesion of the intermediate transfer member. An arrangement for preventing image generation is disclosed. Usually, when the toner adhesion of the image carrier exceeds the toner adhesion of the intermediate transfer body, it is difficult to transfer the toner from the image carrier to the intermediate transfer body, or the toner transferred on the intermediate transfer body is A phenomenon such as reverse transfer on the carrier occurs, and an insect-eating image is easily generated. In this publication, such a phenomenon is taken into consideration, and the toner adhesion of the image carrier is made smaller than the toner adhesion of the intermediate transfer member. Specifically, the surface tension or surface energy of the image carrier and the intermediate transfer member is regarded as a physical quantity representing the easiness of toner adhesion to each of them, and the surface tension (or surface energy) of the image carrier ≦ intermediate transfer member By satisfying the following condition, the surface tension (or surface energy) of [Formula A], the transferability is improved,
The generation of the worm-like image is prevented. Also,
In this publication, a lubricant is applied to an image carrier and an intermediate transfer member during actual use in order to reduce the adhesive force with the toner, which gradually increases in the image forming process, and the amount of application per unit time is reduced. To adjust.

As described above, in order to prevent the occurrence of a bug-like image, it is only necessary to control the adhesion of the toner to the image carrier and the intermediate transfer member. It is effective to apply a lubricant. However, as a method of applying the lubricant, for example, “n
"Intermittently apply lubricant once per sheet (eg, 50 sheets)" (Japanese Patent Application Laid-Open No. H8-211755, U.S. Pat.
No. 5,538,827), an insect-like image occurs when the lubricant becomes insufficient shortly before application,
When a large number of sheets are to be output, there is a problem that the throughput is reduced because the idle rotation is intermittently performed. In addition, since the amount of application is set based on the average amount of consumption, for example, “how many mg is consumed for every 1,000 sheets”, it takes time and it is difficult to adjust to the optimum condition.

Further, in the above publication, in an image carrier or an intermediate transfer member coated with a lubricant, the lubricant on the surface greatly contributes to the surface tension (or surface energy). (Or surface energy) is not available. Therefore, in order to prevent the occurrence of a bug-eating image, application of a lubricant to an image carrier or an intermediate transfer member cannot always be controlled, and cannot be used as an effective characteristic value for a bug-eating. .

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object the following:
An object of the present invention is to provide an image forming apparatus capable of preventing occurrence of a bug-like image when a lubricant is applied to at least one of the surface of the image carrier and the surface of the intermediate transfer member.

[0009]

According to a first aspect of the present invention, a toner image formed on an image carrier is primarily transferred onto an intermediate transfer member, and the toner image is transferred to a transfer material. In the image forming apparatus of the secondary transfer type, the respective static friction coefficients of the surface of the image carrier and the surface of the intermediate transfer member in the actual use state are calculated as: Static coefficient of friction of intermediate transfer member−Static friction coefficient of surface of image carrier> − 0.1.

According to a second aspect of the present invention, there is provided the image forming apparatus according to the first aspect, further comprising a lubricant applying means for applying a lubricant to at least one of the surface of the image carrier and the surface of the intermediate transfer body. The lubricant is applied such that the respective static friction coefficients of the surface of the carrier and the surface of the intermediate transfer member have a relationship of: static friction coefficient of the surface of the intermediate transfer member−static coefficient of friction of the surface of the image carrier> −0.1. It is characterized by the feature.

According to a third aspect of the present invention, in the image forming apparatus of the first or second aspect, the static friction coefficient of the image bearing member is set to 0.1.
2 to 0.35, and the coefficient of static friction of the intermediate transfer member is 0.25 to 0.5.

In the image forming apparatus according to any one of the first to third aspects, the surface static friction coefficient of the image carrier and the intermediate transfer member in an actual use state is: static friction coefficient of the intermediate transfer member surface−static friction coefficient of the image carrier surface. > −0.1, the toner is easily transferred from the image carrier to the intermediate transfer member, or the toner transferred on the intermediate transfer member is reverse-transferred onto the image carrier. As a result, it is possible to prevent the occurrence of insect-eating images. Also,
Since the coefficient of static friction is used as a characteristic value representing the adhesion of the toner, even when at least one of the surface of the image carrier and the surface of the intermediate transfer member is coated with a lubricant, the measurement is performed in real time and directly. be able to. Therefore, in the actual use state of the image forming apparatus, the lubricant can be applied based on the measurement result of the coefficient of static friction so that the relationship represented by the above inequality is always satisfied. Can be prevented from occurring.

According to a fourth aspect of the present invention, in the image forming apparatus of the first or second aspect, the coefficient of static friction is set between the image bearing member and the intermediate transfer member and a contact member for measuring the static friction coefficient. The measurement is carried out by sandwiching.

In the image forming apparatus of the present invention, the coefficient of static friction is measured by interposing a buffer between the image carrier and the intermediate transfer member and a contact member for measuring the coefficient of static friction. An average pressure can be applied to the image bearing member and the intermediate transfer member having the deformation due to the surface roughness and the softness of the material itself, so that an accurate static friction coefficient can be obtained.

According to a fifth aspect of the present invention, in the image forming apparatus of the second aspect, as the means for applying the lubricant to the intermediate transfer member, a brush for scraping and applying a solid lubricant and a part of the fixed lubricant is applied. A roller is provided, and a linear pressure of the brush roller with respect to the solid lubricant is set to 0.15 gf / mm or less.

In the image forming apparatus according to the present invention, the means for applying the lubricant to the intermediate transfer member includes a solid lubricant and a brush roller for scraping and applying a part of the fixed lubricant. The linear pressure of the brush roller against the solid lubricant is set to 0.15 gf / mm or less. Since the organic fatty acid group of the solid lubricant easily adheres strongly to the intermediate transfer member and the thin film state is easily maintained, the thin film state can be sufficiently formed even with a very small amount of application.

According to a sixth aspect of the present invention, in the image forming apparatus of the second aspect, as the means for applying the lubricant to the intermediate transfer member, a brush for scraping and applying a solid lubricant and a part of the fixed lubricant. A roller and a contact member that comes into contact with the brush roller to scrape off toner are provided, and the biting amount of the contact member with respect to the brush roller is set to 0.3 mm or less.

In the image forming apparatus according to the present invention, as the means for applying the lubricant to the intermediate transfer member, a brush roller for scraping and applying a part of the solid lubricant and the fixed lubricant to the intermediate transfer body, A contact member for contacting and scraping off the toner is provided, and the bite amount of the contact member with respect to the brush roller is set to 0.3 mm or less, so that the rotation of the brush roller by the rotation of the intermediate transfer member is not hindered, The tip of the brush roller can be cleaned. Therefore, it is possible to prevent the brush tip from being contaminated by the residual toner on the intermediate transfer member at the time of continuous output of a color image, so that it is possible to apply a good lubricant, and it is possible to suppress the occurrence of a bug-like image.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment applied to a color copying machine as an image forming apparatus according to the present invention will be described below. First, the schematic configuration and operation of the color copying machine according to the present embodiment will be described. FIG. 1 is a schematic configuration diagram of the entire color copying machine according to the present embodiment. In FIG.
A belt-shaped photoreceptor (hereinafter, referred to as a “photoreceptor belt”) 1 as a latent image carrier is provided between the rotating rollers 2 and 3, and driven by the rotating rollers 2 and 3 in a direction indicated by an arrow A in FIG. (Clockwise). Around the photoreceptor belt 1, a charging device 4 as a charging unit for uniformly charging the photoreceptor surface, a neutralization lamp L, a laser writing unit 5 as an exposure device for forming an electrostatic latent image, a photoreceptor belt Cleaning unit 15, a revolver developing device 6 integrally provided with three developing units accommodating yellow, magenta, and cyan color developers (hereinafter, referred to as toner), separately from the revolver developing device 6. A black developing unit 7 containing the black developer (hereinafter, referred to as black toner) is provided. The revolver developing device 6 has a
There is a mechanism for selecting the developing unit by rotation of 0 degrees. When these developing units operate, the black developing unit 7 moves to a position separated from the photosensitive belt 1. The movement is controlled by the rotation of the cam 45.

The laser writing unit 5 contains a semiconductor laser (not shown), a polygon mirror rotated by a drive motor, an f-θ lens, and a mirror in a unit case, and is incorporated in a lower part of the apparatus body. ing.

The upper rotating roller 3 of the photosensitive belt 1
An intermediate transfer belt 10 as an intermediate transfer member is provided at a portion where the intermediate transfer belt is wound. The intermediate transfer belt 10 has belt rotation rollers 11 and 12
The belt rotation rollers 11 and 12 are driven to rotate in a direction indicated by an arrow B (counterclockwise) in FIG. A cleaning unit 16 for the intermediate transfer belt and a transfer roller 14 as a secondary transfer unit that comes in contact with and separates from the intermediate transfer belt 10 are provided at a portion where the intermediate transfer belt 10 is wound around the belt rotation roller 11. Have been.

Photosensitive belt cleaning unit 15
Are a cleaning blade 15A for cleaning residual toner on the photosensitive belt 1;
B and 15C. The intermediate transfer belt cleaning unit 16 includes a cleaning blade 16A for cleaning the surface of the intermediate transfer belt 10, an auger 16B for conveying toner, an arm 16C for contacting and separating the cleaning blade, and the like. The cleaning blade 16A for the intermediate transfer belt is kept at a position separated from the surface of the intermediate transfer belt 10 during image formation by the contact / separation arm 16C. The transfer belt 10 is in contact with the surface of the transfer belt 10.

The waste toner scraped off from the photosensitive belt 1 and the intermediate transfer belt 10 by the cleaning blades 15A and 16A, respectively, is collected in a collecting container 15C, and the collecting container 15C is appropriately replaced. The waste toner scraped off from the intermediate transfer belt 10 is transported toward the front of the drawing by an auger 16B provided in the cleaning unit 16 for the intermediate transfer belt, and is further collected by a transport unit (not shown). The container is transported to the container 15C.

The photosensitive belt 1 is provided with a photosensitive belt coating device 90 provided in the cleaning unit 15.
Thereby, a lubricant is applied. Also,
Similarly, a lubricant is applied to the intermediate transfer belt 10 by an intermediate transfer belt coating device 100 provided in the cleaning unit 16. The lubricant applying devices 90 and 100 will be described later in detail.

The photosensitive belt 1, the charging device 4,
Intermediate transfer belt 10, cleaning unit 15, 1
6 and the like are integrally formed as a process cartridge, and the waste toner collecting container 15C is removably incorporated in the process cartridge and is configured to be replaceable when its life is reached. Further, the revolver developing device 6 and the black developing unit 7 can be replaced at the end of their life. The front frame 8 of the main body of the color copier has a structure that can be opened in order to facilitate exchangeability and processing of a jammed sheet.

In the above-described color copying machine, the photosensitive belt 1 is uniformly charged by the charging device 4 and then scanned by the laser beam 5D modulated based on image information by the laser writing unit 5. Exposure causes an electrostatic latent image to be formed on the surface. The image information used for exposure is monochromatic image information obtained by decomposing a desired full-color image into yellow, magenta, cyan, and black color information. A laser beam 5D generated by a semiconductor laser (not shown) based on this image information is rotationally scanned by a polygon mirror driven at high speed by a drive motor, passed through an f-θ lens, and adjusted in optical path by a reflection mirror. You.

The electrostatic latent image formed on the photoreceptor belt 1 is developed by the revolver developing device 6 with a predetermined yellow toner, a magenta toner and a cyan toner, respectively. Further, the electrostatic latent image formed based on the black color information is developed by the black developing unit 7 with black toner,
Each color image (toner image) is sequentially formed on the photoconductor 1.

Each single-color image (toner image) formed on the photosensitive belt 1 rotating in the direction of arrow A in FIG. 1 is applied to the bias means 13 for each of the single colors of yellow, magenta, cyan, and black. Due to the predetermined transfer bias, primary transfer is performed by superimposing the intermediate transfer belt 10 sequentially on the intermediate transfer belt 10 rotating in the direction of arrow B in synchronization with the photosensitive belt 1. Yellow, magenta, superimposed on the intermediate transfer belt 10
The cyan and black images are stored in the paper feed tray (paper feed cassette) 1
From 7, the sheet is passed through a sheet feeding roller 18, a conveying roller pair 19, and a registration roller pair 20, and is collectively rotated by the transfer roller 14 onto the recording medium conveyed to the transfer unit at a time, and is secondarily photographed. After the completion of the secondary transfer, the image is fixed by the fixing device 50 to complete a full-color image. The recording material on which the full-color image is formed is discharged to a discharge stack 52 via a discharge roller pair 51.

At the time of repeat copying, image formation on the photoreceptor belt 1 is performed at a predetermined timing, for example, yellow (first color) at a predetermined timing following the image forming process of the first sheet, for example, a black (fourth color) image. Proceed to an image forming process. In the intermediate transfer belt 10, a second yellow toner image is formed in a region where the surface of the intermediate transfer belt 10 has been cleaned by the cleaning blade 16 </ b> A following the batch secondary transfer process of the first four-color superimposed image onto the recording medium. The primary transfer is performed. After that,
The operation is similar to that of the first sheet.

The copy mode for obtaining four full colors has been described above. However, in the case of the three-color copy mode and the two-color copy mode, the same operation as described above is performed for the designated color and the number of times. become. In the case of the single-color copy mode, only the developing unit of that color is set in the developing operation (spring) until the predetermined number of sheets is completed, and the intermediate transfer belt 10 reciprocates while being in contact with the photosensitive belt 1. Drive at a constant speed in the direction
6A also performs a copying operation in a state of being kept in contact with the intermediate transfer belt 10.

The conditions of the present embodiment are shown below. Photoreceptor belt 1: OPC Intermediate transfer belt 10: Carbon dispersed ETFE or PVdF Surface resistivity ρs = 10 ⁷ to 10 ¹⁰ Ω / □ Thickness: about 150 μm, Surface roughness = several μm Belt rotating roller 11: On metal roller A rubber layer is thinly coated. Surface resistivity ρs = 10 ¹⁰ Ω / □ or less Grounded and also used as a counter electrode of the transfer roller 14

Under these conditions, the photosensitive belt 1
In addition, an evaluation experiment was performed on an insect-like image when the static friction coefficient of the intermediate transfer belt 10 was changed. The evaluation of the worm-like image was a five-point silent test evaluation, with rank 5 being the best and rank 1 being the worst. The evaluation criterion of rank 5 is a level at which no worm-eating image occurs, and rank 3 is a minimum image quality level allowed in the market.

FIG. 3 shows the results of evaluation of the worm-like image when the photosensitive belt 1 having a static friction coefficient in the range of 0.2 to 0.35 is used. Taking the coefficient of static friction of the intermediate transfer belt 10 on the horizontal axis, four types of images (black image, cyan image,
The average value of the five-step rank evaluation for the cyan and magenta superimposed images and the magenta and yellow superimposed images was plotted. Thus, in order to obtain an image quality of rank 3 or higher, the static friction coefficient of the photoreceptor belt 1 must be 0.2 to 0.35,
It is sufficient that the static friction coefficient of the intermediate transfer belt 10 is 0.25 to 0.5. In order to obtain image quality in which no insect-like image of rank 5 is generated, the static friction coefficient of the photosensitive belt 1 is 0.22 to 0.52. 0.3 and the static friction coefficient of the intermediate transfer belt 10 should be controlled to 0.26 to 0.38. The combination of the static friction coefficient of the photoreceptor belt 1 and the intermediate transfer belt 10 for obtaining an image quality of rank 3 or higher is as follows: (Static friction coefficient of the intermediate transfer belt 10) − (Static friction coefficient of the photoreceptor belt 1)> −0.1 is satisfied. From this result, if the coefficient of static friction of the intermediate transfer belt 10 is larger than the coefficient of static friction of the photoreceptor belt 1, or if the difference between the two is less than 0.1, the intermediate transfer belt 10 Is higher than the toner adhesion of the photoreceptor belt 1, and it can be said that good transfer is performed. Here, when the static friction coefficient of the intermediate transfer belt 10 is smaller than the static friction coefficient of the photoconductor belt 1 by 0.1 or more, the toner adhesion to the photoconductor belt 1 exceeds the adhesion to the intermediate transfer belt 10. Intermediate transfer belt 10 from above belt 1
A phenomenon occurs in which the toner transferred above is reversely transferred onto the photoreceptor belt, and an insect-eating image occurs.

FIG. 4 shows that the static friction coefficient is 0.39 to 0.45.
5 shows evaluation results of an insect-eating image when the photoreceptor belt 1 is used. The static friction coefficient of the intermediate transfer belt 10 is plotted on the horizontal axis, and the average value of the rank evaluation for the above four types of images is plotted. From this, the evaluation of the insect-eating image becomes rank 3 or higher in the narrow range of the static friction coefficient of the intermediate transfer belt 10 of 0.46 to 0.49. − (Static friction coefficient of photoreceptor belt 1)> − 0.1.

FIG. 5 shows the result of evaluation of an insect-like image when the photosensitive belt 1 having a static friction coefficient of 0.2 or less is used. The static friction coefficient of the intermediate transfer belt 10 is plotted on the horizontal axis, and the average value of the rank evaluation for the above four types of images is plotted. As a result, the static friction coefficient of the photoreceptor belt 1 is set to 0.
When the value is smaller than 2, it can be seen that rank 3 or higher cannot be achieved even if the static friction coefficient of the intermediate transfer belt 10 is changed. This is because the coefficient of static friction of the photoreceptor belt 1 is too small, so that the photoreceptor belt 1 is already defective at the time of development, and an over-eating image is generated on the photoreceptor belt 1. (Hereinafter, margin)

Summarizing the above results, in the state where the color copier is actually operated to form an image, that is, in the actual use state, (the coefficient of static friction of the intermediate transfer belt 10)-(the coefficient of static friction of the photosensitive belt 1) If the relationship of (static friction coefficient)>-0.1 is satisfied, generation of an insect-eating image can be suppressed, and image quality of rank 3 or higher can be obtained. More specifically, the inequality is satisfied, and the static friction coefficient of the photoreceptor belt 1 is controlled from 0.2 to 0.35, and the static friction coefficient of the intermediate transfer belt 10 is controlled from 0.25 to 0.5. Can be prevented.

Here, the coefficient of static friction can be determined as follows. In this embodiment, a portable static friction meter 200 (HEIDON manufactured by Shinto Kagaku Co., Ltd.)
Tribogear Muse TYPE94i200) was used. As shown in FIG. 7, the static tribometer 200 is used by sandwiching a pressure plate 210 on the inner peripheral side of the belt in order to make the contact between the photosensitive belt 1 and the intermediate transfer belt 10 and the flat indenter of the static tribometer uniform. Is done. Here, the photosensitive belt 1
In the case where a drum-shaped member is used instead of the intermediate transfer belt 10, the configuration shown in FIG. 8 may be used. In this case, the contact area is slightly reduced and the variation in data is slightly increased, but this does not cause a problem in averaging or the like.

As shown in FIG. 9B, the coefficient of static friction is obtained by measuring the maximum frictional force acting between the flat indenter 201 provided at the lower portion of the static friction meter 200 and the belt, and pressing each other in the vertical direction. And can be obtained by the following ratio. Also,
This flat indenter 201 is about 4 mm with a metal probe of Φ40.
It is as light as 0 gf and can avoid problems such as scratching of the belt surface. Further, the measurement is performed by attaching a cushioning material 202 between the flat indenter 201 and the belt. In the present embodiment, a thin cloth is used for the cushioning member 202, but natural fibers such as cotton and hemp, synthetic resin fibers such as rayon and polypropylene, metal fibers, and nonwoven fabrics can also be used. Further, a foam having an appropriate hardness, a thin film having an appropriate unevenness, or the like may be used.

The reason why such a cushioning material 202 is provided between the plane indenter 201 and the belt is explained with reference to FIGS.
This will be described with reference to FIG. As shown in FIG. 9A, the intermediate transfer belt 10 (or the photoreceptor belt 1) is deformed by the surface roughness and the softness of the material itself. For example, the intermediate transfer belt 10 used in the present embodiment has Ra 10 μm
It is as follows. Further, since the toner T is a powder,
It follows the unevenness of the belt surface and adheres to the lower part of the recess. Therefore, the coefficient of static friction of the belt surface, which is expressed as the actual adhesive force between the belt and the toner, needs to be a measured value including such concave portions of the uneven surface. Therefore, as shown in FIG. 9B, the measurement is performed using a cushioning material 202 of a material that is flexible and easy to loosen so as not to damage the mating member, while being able to conform to the uneven surface. As a result, an average pressure can be applied to the belt, and a highly accurate static friction coefficient can be obtained. The fiber bundle of the cloth used in the present embodiment has a thickness of about 0.5 mm, and furthermore, the fibers thereof are about 5 to 30 μm. In this case, the fibers are appropriately deformed and sometimes loosened little by little to apply an average pressure to the belt. What to use for the buffer 202 may be selected according to the surface roughness and softness of the target surface.

By the way, in addition to the measurement by the static friction meter 200, a method of obtaining the angle θ at which the indenter starts to slide down by applying a gradient and obtaining it from μ = tan θ as described in JP-A-8-211775. There is also. In this publication, the ASID of HEIDON-14DR manufactured by Shinto Kagaku Co., Ltd.
A polyethylene terephthalate (PET) sheet is wound around a flat indenter specified by TM D-1894, and a vertical load of 200 gf is applied between the object to be measured and the flat indenter to 100 mm / min. The slip resistance of the PET sheet and the sample sheet when the sample sheet is moved at the speed of is measured. However, PE used for indenter
As described above, the stretch resin material such as T cannot reproduce the state in which the toner adheres while deforming according to the unevenness of the intermediate transfer belt 10, and the frictional force is observed only at the surface convex portion. Further, in such a measuring instrument, since a sample piece is cut out and a sample sheet is created, it is a half-destructive inspection, and real-time evaluation such as measurement at any time during running cannot be performed. Therefore, a portable static tribometer is desirable.

In the present embodiment, a lubricant is applied to at least one of the surface of the photoreceptor belt 1 and the surface of the intermediate transfer belt 10 based on the measurement result of the static friction coefficient as described above, and the static friction coefficient of both of them is reduced. The relationship expressed by the above inequality is maintained over time. Since the coating device 90 for the photoreceptor belt and the coating device 100 for the intermediate transfer belt have the same configuration, the coating device 100 for the intermediate transfer belt will be described below as an example. FIG. 10 is a partially enlarged view of a lubricant applying apparatus 100 for applying a lubricant to the intermediate transfer belt, and FIG. 11 is a perspective view of the enlarged view. The lubricant applying device 100 is provided in the intermediate transfer belt cleaning unit 16 and includes a solid lubricant bar 101 and a brush roller 102 for applying the lubricant to the intermediate transfer belt 10. The solid lubricant bar 101 is obtained by dissolving a lubricating oil additive containing zinc stearate as a main component and then cooling and solidifying the solid lubricant bar 101, and is formed into a bar shape. During the lubricant applying operation by the lubricant applying apparatus 100, the entire intermediate transfer belt applying apparatus 100 is operated by a solenoid (not shown) on the intermediate transfer belt 10 side so that the brush roller 102 is in contact with the surface of the intermediate transfer belt 10 for a predetermined time. And the brush roller 102 is driven to rotate by the rotation of the intermediate transfer belt 10. At this time, the solid lubricant bar 101 has its own weight (50 gf or less / 330 mm
(Width), the solid lubricant bar 101 is partially scraped by the brush roller 102, and the solid lubricant adhered to the surface of the brush roller 102 adheres to the surface of the intermediate transfer belt 10 to form a coating layer. Is formed. Here, the reason that the solid lubricant bar 101 is applied to the brush roller 102 by its own weight is that even if the pressure of the solid lubricant bar 101 is extremely low, the solid lubricant is not applied to the intermediate transfer member such as ETFE or PVdF. Since the organic fatty acid group easily adheres strongly and the thin film state is easily maintained, a thin film state can be sufficiently formed even with a very small amount of application. In this embodiment, a slight pressure was applied without using its own weight.
Even with a spring pressure of about f, the static friction coefficient of the intermediate transfer belt 10 deviated from the required value.

As the solid lubricant bar 101, in addition to zinc stearate, barium stearate, lead stearate, iron stearate, nickel stearate, cobalt stearate, copper stearate, strontium stearate, Those having a stearic acid group such as calcium stearate can be used. In addition, the same fatty acid groups, zinc oleate, barium oleate, and lead oleate (hereinafter the same as stearic acid)
Alternatively, zinc palmitate, barium palmitate, and lead palmitate (hereinafter similar to stearic acid) may be used. In addition, caprylic acid, linolenic acid, corinolenic acid and the like can be used as the fatty acid group. Furthermore, candelilla wax, canrunauba wax, rice wax,
Waxes such as wood wax, amber oil, beeswax, and lanolin could also be used. These are organic solid lubricants,
Easy to use because of good compatibility with toner. Further, a Teflon-based or inorganic solid lubricant may be used depending on the toner.

By the way, when actually forming an image,
There are various output formats. For example, when a single monochrome image is output and when a color image is continuously output, the way in which the intermediate transfer belt 10 is soiled and the way in which the brush roller 102 is soiled are different. It will be different. The differences between the output formats are shown below. When one monochrome / color image is output Since the intermediate transfer belt 10 is pre-rotated before the latent image is formed, the intermediate transfer belt cleaning blade 16A is in contact with the intermediate transfer belt 10 and the intermediate transfer belt 1
Above 0 is in a clean state. When continuously outputting monochrome images When continuously outputting monochrome images, use the cleaning blade 1
6A is always in contact with the intermediate transfer belt 10 and thus is not dirty. When the color image is continuously output, the cleaning blade 16A is separated at the time of forming the n-th image, and the cleaning blade 1A is only used for the secondary transfer.
6A operates, but since the (n + 1) th image formation is started immediately, the lubricant can be applied only at the time of cleaning the nth sheet. However, as shown in FIG. 4, the toner T remains on the intermediate transfer belt 10 after the secondary transfer, and the remaining toner T stains the brush roller 102, so that it is difficult to control the application of the lubricant, and the intermediate transfer belt The coefficient of static friction of 10 gradually increases. FIG. 6 shows an example. In FIG. 6, the horizontal axis represents the number of formed images, and the vertical axis represents the intermediate transfer belt 10.
The coefficient of static friction is shown. As shown in FIG. 6A, at the time of continuous output of a color image, the coefficient of static friction gradually increases and approaches an area where insect biting is likely to occur.

Therefore, in the present embodiment, the brush roller 102 is provided so that the brush tip of the brush roller 102 can be prevented from being stained even during continuous output of a color image.
A projection 110 is provided on the inside of the case so that the toner T is knocked off (see FIGS. 10 and 11). The protrusion 110 has a bite amount with the brush roller 102 of 0.3 mm or less or a degree of touching the surface. Even with this degree, the tip of the brush fiber of the brush roller 102 can be cleaned. According to this biting amount setting, pressure is applied to the brush roller 102 at an extremely low pressure, so that there is no hindrance to the driven rotation of the brush roller 102 due to the rotation of the intermediate transfer belt 10. As described above, even at the time of continuous output of a color image, the tip of the brush is not stained, and it is possible to apply the solid lubricant under the same application conditions as in the case of taking one monochrome sheet. Therefore, FIG.
As shown by (b), the static friction coefficient can be maintained at a constant value, and the occurrence of a bug-like image can be suppressed. Further, as another embodiment, a thin film may be brought into contact with a direction (trading direction) in which the thin film is easily separated from the surface when the brush roller 102 rotates.

In the above embodiment, the coating device 90 for the photoreceptor belt is provided in the cleaning unit 15, but the coating device 90 may be provided outside the cleaning unit 15 instead. In this case, in the example of FIG. 1, a cleaning fur brush roller may be disposed at a position of the brush roller 92 constituting the coating apparatus, and a two-stage cleaning unit including the roller and the cleaning blade 15A may be used.

Further, the present invention is not limited to the above embodiment, but is applicable to all devices utilizing the technical idea of the present invention. The photoreceptor and the intermediate transfer member may have any of a belt shape, a drum shape, and a roller shape.

[0047]

According to the first to third aspects of the present invention, even when at least one of the surface of the image carrier and the surface of the intermediate transfer member is coated with a lubricant, an image of a bug-like image over time is obtained. Can be prevented.

According to the invention of claim 4, there is an excellent effect that an accurate static friction coefficient can be obtained.

According to the fifth aspect of the present invention, there is an excellent effect that the thin film state of the lubricant can be maintained even when the amount of the lubricant applied to the intermediate transfer member is extremely small.

According to the sixth aspect of the present invention, it is possible to apply a good lubricant even at the time of continuous output of a color image, and there is an excellent effect that generation of an insect-like image can be suppressed.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a schematic configuration of a color copying machine according to an embodiment.

FIG. 2 is an explanatory diagram showing an example of an insect-like image.

FIG. 3 is a graph (1) showing an evaluation result of an insect-like image in the present embodiment.

FIG. 4 is a graph (2) showing an evaluation result of an insect-like image in the present embodiment.

FIG. 5 is a graph (3) showing an evaluation result of the worm-like image in the embodiment.

FIG. 6 is a graph showing a change in the static friction coefficient of the intermediate transfer belt when a color image is continuously output in the embodiment.

FIG. 7 is an explanatory diagram showing a method of measuring a static friction coefficient in the embodiment.

FIG. 8 is an explanatory diagram showing a method of measuring a static friction coefficient when an intermediate transfer drum is used as an intermediate transfer member.

FIGS. 9A and 9B are explanatory diagrams illustrating the effect of installing a cushioning material on an indenter when measuring the static friction coefficient.

FIG. 10 is a partially enlarged view of a lubricant applying device according to the embodiment.

FIG. 11 is a perspective view of the lubricant applying device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photosensitive belt 2, 3 rotating roller 4 charging device 5 laser writing unit 6 revolver developing device 7 black developing unit 8 front frame 10 intermediate transfer belt 11, 12 rotating roller 13 bias means 14 transfer roller 15 cleaning for photosensitive belt Unit 16 Intermediate Transfer Belt Cleaning Unit 17 Feed Cassette 18 Feed Roller 19 Conveying Roller Pair 20 Registration Roller Pair 90 Photoconductor Belt Coating Device 92 Brush Roller (for Photoconductor Belt) 100 Intermediate Transfer Belt Coating Device 101 Solid Lubrication Agent bar 102 Brush roller (for intermediate transfer belt) 110 Projection

Claims (6)

[Claims] An image forming apparatus of a system in which a toner image formed on an image carrier is primarily transferred onto an intermediate transfer member and the toner image is secondarily transferred onto a transfer material, wherein the image carrier in an actual use state is provided. An image forming apparatus, wherein each static friction coefficient of the surface of the body and the surface of the intermediate transfer member has a relationship of: static friction coefficient of the surface of the intermediate transfer member-static coefficient of friction of the surface of the image carrier> -0.1. 2. The image forming apparatus according to claim 1, further comprising: a lubricant applying means for applying a lubricant to at least one of the surface of the image carrier and the surface of the intermediate transfer body. Image forming, wherein the lubricant is applied such that each coefficient of static friction on the surface of the intermediate transfer member is such that the coefficient of static friction on the surface of the intermediate transfer member−the coefficient of static friction on the surface of the image carrier> −0.1. apparatus. 3. The image forming apparatus according to claim 1, wherein said image bearing member has a static friction coefficient of 0.2 to 0.35, and said intermediate transfer member has a static friction coefficient of 0.25 to 0.3.
5. An image forming apparatus, comprising: 4. The image forming apparatus according to claim 1, wherein said static friction coefficient is measured by interposing a buffer between said image bearing member and said intermediate transfer member and a contact member for measuring static friction coefficient. An image forming apparatus, comprising: 5. An image forming apparatus according to claim 2, wherein said lubricant applying means on said intermediate transfer member is provided with a solid lubricant and a brush roller for scraping and applying a part of said fixed lubricant. The linear pressure of the brush roller against the solid lubricant is 0.15
gf / mm or less. 6. The image forming apparatus according to claim 2, wherein said lubricant applying means for applying said lubricant to said intermediate transfer member is a brush roller for scraping and applying a part of said solid lubricant and said fixed lubricant. And a contact member for contacting the brush roller to scrape off the toner.
An image forming apparatus characterized by being set to 3 mm or less.