JP2011180352A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus brought into such a state that a toner patch on an intermediate transfer belt can be read over a long period of time, by preventing the reduction of the glossiness of the intermediate transfer belt 8 caused by the adhesion of the external additive of toner and the filler of a paper. <P>SOLUTION: A cleaning web 61 having a hydrophilicity higher than that of the intermediate transfer belt 8 is used to sufficiently recover the external additive and the filler of the paper and prevent the reduction of the glossiness of the intermediate transfer belt 8. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention has a rotatable intermediate transfer member, and transfers the developer image formed in the image forming unit to the intermediate transfer member in the primary transfer unit, and the developer image primarily transferred to the intermediate transfer member is transferred to the intermediate transfer member. The present invention relates to an intermediate transfer type image forming apparatus that performs secondary transfer onto a recording material in a secondary transfer unit.

  In Patent Document 1, the adhering matter adhering to the intermediate transfer belt is removed by a fur brush cleaning device. In order to remove other substances such as toner and external additives that cannot be collected by the fur brush, the cleaning web member is brought into contact with the downstream side in the moving direction of the intermediate transfer belt from the fur brush cleaning device to improve the cleaning property. The configuration is disclosed.

  Japanese Patent Application Laid-Open No. 2004-228688 has an image forming apparatus using an intermediate transfer belt and has a polishing ability provided separately from a cleaning unit that removes residual toner (developer) that has not been transferred from the belt to a recording material. A configuration having a cleaning web is described. The cleaning web refreshes the belt surface by polishing the belt surface to remove adhering substances such as toner external additives and paper filler that have not been removed by the cleaning means. This prevents or reduces the occurrence of belt glossiness reduction, image omission and blurring caused by the above-mentioned adhered substances, and allows the belt to be used over a long period of time.

Japanese Patent Laid-Open No. 10-149033 JP 2006-154374 A

  However, in an image forming apparatus equipped with a cleaning web as in Patent Document 1, substances such as external additives for toner and fillers such as paper sometimes slip through the cleaning web. For this reason, the substance that has passed through the cleaning web is gradually accumulated and covered on the surface of the intermediate transfer belt by electrostatic force due to the transfer bias, application, and pressure with other members. As a result, it adheres to the surface layer of the intermediate transfer belt, and this causes a reduction in gloss (hereinafter referred to as gloss). The reduction in the gloss of the belt causes the optical reading sensor for the position detection toner image to be erroneously detected on the belt, so that the belt in such a state needs to be replaced. That is, the service life of the intermediate transfer belt has been shortened. Here, the adhering matter adhering to the intermediate transfer member is not particularly limited as long as it can actually adhere.

  Further, in the configuration of Patent Document 2, the developer release layer that is the surface layer of the belt is scraped, and not only the belt cleaning property but also the transfer property of the developer image from the image carrier of the image forming unit to the belt, There is a risk that the transferability of the developer image from the belt to the recording material may be deteriorated.

  The present invention has been made in view of the above circumstances. The purpose of this is to reduce the surface of the intermediate transfer member in an intermediate transfer type image forming apparatus, and also to apply adhering substances such as an external additive of the developer and a filler of the recording material from the surface of the intermediate transfer member. Is to be removed. As a result, the glossiness of the surface of the intermediate transfer member caused by the adhering substance can be prevented for a long time, and the position detection developer image formed on the intermediate transfer member can be read by an optical reading device. It is an object of the present invention to provide an image forming apparatus capable of detecting the rotational position of the lens for a long time.

  In order to achieve the above object, a typical configuration of an image forming apparatus according to the present invention includes a rotatable intermediate transfer member, and a developer image formed in an image forming unit is applied to the intermediate transfer member. An image forming apparatus for transferring a developer image transferred by a primary transfer unit and primary transferred to the intermediate transfer member to a recording material by a secondary transfer unit, wherein the secondary transfer unit rotates with respect to the rotation direction of the intermediate transfer member. A first cleaning unit and a second cleaning unit that are disposed in order along the rotational direction of the intermediate transfer member downstream of the transfer unit and upstream of the image forming unit, and for cleaning the surface of the intermediate transfer member. The second cleaning means has a function of cleaning the web member by contacting the intermediate transfer member, the web member is made of a non-conductive porous body, and the surface is subjected to plasma discharge treatment. Intermediate transfer Characterized in that it is set higher hydrophilicity than the surface of the.

  According to the present invention, in an intermediate transfer type image forming apparatus, the surface of the intermediate transfer member is less worn, and adhering substances such as an external additive of a developer and a filler of a recording material are effectively removed from the surface of the intermediate transfer member. Can be removed. As a result, the glossiness of the surface of the intermediate transfer member caused by the adhering substance can be prevented for a long time, and the position detection developer image formed on the intermediate transfer member can be read by an optical reading device. It is possible to provide an image forming apparatus capable of detecting the rotational position of the image forming apparatus over a long period of time.

1 is a configuration diagram of an image forming apparatus 100 according to a first embodiment. (A) is a partially enlarged view of FIG. 1, (b) is a state diagram of the second cleaning device that is shifted to the non-operation position. Diagram explaining the relationship between the contact angle of the belt and the web Explanatory drawing showing the measurement method of contact angle Effect explanatory drawing of Example 1 Effect explanatory drawing of Example 2

[Example 1]
(1) Schematic Configuration of Image Forming Apparatus Example FIG. 1 is a configuration diagram of an image forming apparatus 100 in this embodiment. FIG. 2A is a partially enlarged view thereof. The apparatus 100 is a tandem intermediate transfer electrophotographic 4-color full-color laser printer in which a plurality of image forming units are arranged in parallel. That is, a color image can be formed on the recording material S based on the electrical image information (image signal) input from the host device 300 to the control circuit unit (control means) 200. The host device 300 is a personal computer (PC), an external scanner (image reader), a terminal on a network, a partner facsimile, a word processor, or the like, and is connected to the control circuit unit 200 via an interface unit. The recording material S is a recording medium on which a toner image can be formed, and is a sheet-like member such as paper, an OHT sheet, a label, or a cloth. The control circuit unit 200 includes a CPU (arithmetic unit), and exchanges various electrical information with an operation unit (not shown) including a display unit and the host device 300. The control circuit unit 200 monitors and controls the operation of each device in the apparatus 100, and comprehensively controls the printing operation (image forming operation) of the apparatus 100 according to a predetermined control program and a reference table.

  In the apparatus 100, first to fourth image forming portions PY, PM, PC, and PK are arranged in a horizontal direction (lateral direction) in order from the left side to the right side in the drawing (tandem). Type). Each image forming unit is an electrophotographic image forming mechanism having the same configuration except that the color of the developer (hereinafter referred to as toner) accommodated in the developing device 4 is different. Each image forming unit of the present example has a rotating drum type electrophotographic photosensitive member (first image carrier: hereinafter referred to as a drum) 1 on which an electrostatic latent image is formed. Each drum 1 is rotationally driven at a predetermined speed in a counterclockwise direction indicated by an arrow by a driving means (not shown). Further, it has a drum charger 2, an image exposure device 3, a developing device 4, a primary transfer charger 5, and a drum cleaning device 6 as process means acting on the drum 1. The charger 2 is a charging unit that uniformly charges the surface of the drum 1 to a predetermined polarity and potential. The image exposure apparatus 3 is a laser scanner unit in this embodiment. The unit 3 includes a semiconductor laser as a light source device, a polygon mirror, an fθ lens, and the like, and the surface of the drum 1 subjected to the charging process of each image forming unit is modulated according to the image information of the corresponding color. Scan exposure with light L. As a result, an electrostatic latent image corresponding to the image information is formed on the surface of each drum 1. The developing device 4 is a developing unit that visualizes the electrostatic latent image formed on the surface of the drum 1 as a toner image (developer image). The developing device 4 of the first image forming unit PY contains yellow (Y color) toner. The developing device 4 of the second image forming unit PM contains magenta (M color) toner. The developing device 4 of the third image forming unit PC contains cyan (C color) toner. The developing device 4 of the fourth image forming unit PK contains black (K color) toner. The drum cleaning device 6 is a cleaning unit that removes primary transfer residual toner on the surface of the drum 1.

  An intermediate transfer belt unit 7 is disposed below the image forming portions PY, PM, PC, and PK. The unit 7 includes a flexible endless belt (second image carrier: hereinafter referred to as a belt) 8 as an intermediate transfer member. In addition, a driving roller 9, a secondary transfer inner roller 10, and a tension roller 11 that suspends and stretches the belt 8 are provided. The belt 8 is rotationally driven by a roller 9 at the same peripheral speed as the drum 1 in the clockwise direction of the arrow. The primary transfer charger 5 of each image forming unit is a transfer roller (conductive charging roller) in this example, and is disposed inside the belt 8. Each transfer roller 5 is in pressure contact with the lower surface of the corresponding drum 1 via a belt portion between the roller 9 and the roller 11. A contact portion (nip portion) between each drum 1 and the belt 8 is a primary transfer portion T1. A secondary transfer outer roller 12 is pressed against the roller 10 via a belt 8. The roller 12 is a conductive charging roller. A contact portion (nip portion) between the belt 8 and the roller 12 is a secondary transfer portion T2.

  Two cleaning devices are disposed in a belt section downstream of the secondary transfer portion T2 and upstream of the image forming portion PY with respect to the belt rotation direction (intermediate transfer member rotation direction). That is, a first cleaning device (first cleaning unit) 50 and a second cleaning device (second cleaning unit) 60 are arranged in order along the belt rotation direction. Both the first cleaning device 50 and the second cleaning device 60 are devices that clean (clean) the surface (image forming area surface) of the belt 8 after the secondary transfer process.

  The operation for forming a full-color image is as follows. The drums 1 of the image forming units PY, PM, PC, and PK are rotationally driven at a predetermined control speed in the counterclockwise direction indicated by the arrow. The belt 8 is also rotationally driven at a speed corresponding to the speed of the drum 1 in the clockwise direction of the arrow (forward direction with respect to the drum rotation). Unit 3 is also driven. In synchronization with this drive, the charger 2 uniformly charges the surface of the drum 1 to a predetermined polarity and potential at each control timing in each image forming unit. The unit 3 scans and exposes the surface of each drum 1 with a laser beam L modulated according to image information of each color. As a result, an electrostatic latent image corresponding to the image information of the corresponding color is formed on the surface of each drum 1 with a predetermined control timing. Then, the electrostatic latent image is developed as a toner image by the developing device 4.

  By the electrophotographic image forming process operation as described above, a Y toner image corresponding to the Y color component of the full color image is formed on the drum 1 of the first image forming unit PY. Then, the toner image is primarily transferred onto the belt 8 at the primary transfer portion T1. An M color toner image corresponding to the M color component of the full color image is formed on the drum 1 of the second image forming unit PM. The toner image is primary-transferred at the primary transfer portion T1 while being superimposed on the Y-color toner image already transferred onto the belt 8. A C-color toner image corresponding to the C-color component of the full-color image is formed on the drum 1 of the third image forming unit PC, and this toner image is already transferred onto the belt 8 in the primary transfer unit T1. Superimposed on the + M color toner image is primarily transferred. A K color toner image corresponding to the K color component of the full color image is formed on the drum 1 of the fourth image forming unit PK. Then, the toner image is primary-transferred at the primary transfer portion T1 while being superimposed on the Y color + M color + C color toner image already transferred onto the belt 8. In each image forming unit, the primary transfer of the toner image from the drum 1 to the belt 8 is applied to the roller 5 from the bias applying means (power supply unit) E5 with a transfer bias having a predetermined potential opposite to the normal charging polarity of the toner. This is done by the electric field applied and the nip pressure of the transfer portion. In this way, a four-color full-color unfixed toner image of Y color + M color + C color + K color is synthesized and formed on the belt 8. In each image forming unit, the toner remaining on the surface of the drum 1 after the primary transfer of the toner image to the belt 8 is removed by the drum cleaning device 6.

  On the other hand, the recording material (transfer material) S stored in the feeding unit 30 is held at a predetermined feeding position by the lifter plate 31 and fed one by one by the feeding separation unit 32 at a predetermined control timing. The Further, the recording material S is conveyed by the feeding / conveying unit 33, subjected to registration adjustment by the registration unit 34, and then conveyed to the secondary transfer portion T2 in synchronization with the toner image on the belt 8. This synchronization control is performed as follows. That is, the toner image for detecting the belt position formed on the surface of the belt 8 by the image forming unit is read by the optical reading device 12 disposed opposite to the belt 8, and the read signal is controlled by the control circuit unit 200. To enter. The control circuit unit 200 performs the above-described synchronization control by detecting the rotational position of the belt 8 based on the input read signal.

  The recording material S introduced into the secondary transfer portion T2 is nipped and conveyed at the nip of the secondary transfer portion T2. A predetermined secondary transfer bias is applied from the bias applying means E12 to the secondary transfer outer roller 12 while the recording material S passes, and the toner images on the belt 8 are sequentially secondarily transferred to the recording material S. The The recording material S exiting the secondary transfer portion T2 is separated from the belt 8 and conveyed to the fixing unit 37 by the pre-fixing conveyance unit 36, and the unfixed toner image is fixed to the recording material S by the fixing unit 37. It is fixed as an image.

  In the single-sided printing mode, the recording material S that has exited the fixing unit 37 is conveyed by the discharge unit 38 and discharged to the discharge tray 39. In the double-sided printing mode, the recording material S on which the first-surface image has been formed that has exited the fixing unit 37 is conveyed to the reversing unit 40 and the front and back are reversed. Then, the recording material S is transported again to the feeding transport unit 33 and the resist unit 34 through the duplex transport unit 41, undergoes secondary transfer of the image to the second surface, and fixed by the fixing unit 37, and is discharged by the discharge unit 38. It is conveyed and discharged to a discharge tray 39.

  On the other hand, in the secondary transfer portion T2, toner, external additives, and the like remaining on the belt 8 after the secondary transfer process of the toner image to the recording material S are removed by the first cleaning device 50 and the second cleaning device 60. .

(2) Intermediate transfer belt The intermediate transfer belt 8 is roughly classified into a resin belt represented by polyimide and the like, and an elastic belt (elastic intermediate transfer belt) using an elastic layer as a surface layer. In the present invention, the intermediate transfer belt 8 as an intermediate transfer member may be a resin belt or an elastic belt. It is known that the elastic belt is soft because the surface layer is an elastic layer, and the pressure acting on the toner at the transfer portion can be reduced. The void phenomenon is a phenomenon that occurs during transfer due to a change in toner. When an image is transferred, a large pressure is applied to the image, so that the toner undergoes stress deformation and the cohesive force between the toners increases. This is a phenomenon in which a part of the image remains on the drum 1 without being transferred. This is particularly noticeable in characters and line images. In this respect, the intermediate transfer belt 8 is more preferably an elastic belt.

  In this embodiment, the belt 8 has an elastic layer and uses an elastic belt having a multilayer belt structure. More specifically, a resin endless belt is used as a base material, and the surface thereof is covered with an elastic rubber layer. Resin materials such as polyimide, PET, and PVDF are used for the material of the base material. Further, silicon rubber, urethane rubber or the like is used as the material of the elastic layer. With this elastic layer, a stable transfer nip is formed in the primary transfer portion T1 and the secondary transfer portion T2, and high-quality toner images can be transferred to various recording material S transfer materials.

(3) First Cleaning Device and Second Cleaning Device (3-1) First Cleaning Device The first cleaning device 50 is a device that mainly removes residual toner (residual developer) from the surface of the belt 8 after the secondary transfer. is there. In this embodiment, since an elastic belt having an elastic layer as a surface layer is used as the belt 8, it is desirable that the belt cleaning means has a small contact load on the belt. Therefore, in the present embodiment, the first cleaning device 50 is an electrostatic fur brush cleaning device having a function of cleaning the electrostatic fur brush against the belt. In this cleaning device, a rotatable fur brush having conductive fibers implanted or wound around the surface of a metal shaft is brought into contact with the belt 8 to apply a bias having a polarity opposite to the polarity of the toner. Thus, residual toner is electrostatically adsorbed and removed from the belt surface by the fur brush, and the contact load on the belt 8 is small.

  An electrostatic fur brush cleaning device as the first cleaning device 50 in this embodiment will be described with reference to FIG. The apparatus 50 includes first and second parallel fur brushes 51 a and 51 b that are rotatably disposed inside an apparatus housing 55. The fur brushes 51a and 51b have conductive fibers implanted on the surface of the metal shaft, and have a length that sufficiently covers the width of the image forming area on the belt surface (the size of the image forming area in the direction perpendicular to the belt moving direction). It is what you have. The second fur brush 51b is located downstream of the first fur brush 51a in the belt moving direction. Both the first and second fur brushes 51 a and 51 b are in contact with the surface of the belt 8. In addition, metal bias rollers 52a and 52b are arranged in parallel with the first and second fur brushes 51a and 51b, respectively, at positions where they contact the conductive fibers of the fur brush. Further, cleaning blades 53a and 53b are disposed in contact with the bias rollers 52a and 52b, respectively. Opposing rollers 54a and 54b are disposed on the opposite side (belt inner surface side) of the first and second fur brushes 51a and 51b with the belt 8 interposed therebetween.

  The first and second fur brushes 51a and 51b are rotationally driven in the counter direction with respect to the rotation direction (traveling direction) of the belt 8 at the contact portion with the belt. The bias rollers 52a and 52b are rotationally driven in the forward direction in the rotation direction of the fur brush at the contact portions between the first and second fur brushes 51a and 51b, respectively. The cleaning blades 53a and 53b are in contact with the counter with respect to the rotation direction of the bias rollers 52a and 52b, respectively. A cleaning bias is applied to the bias rollers 52a and 52b from bias applying means E52a and E52b, respectively. The bias applying means E52a and E52b apply biases having opposite polarities. In the present embodiment, a cleaning bias having a polarity opposite to the normal charging polarity of the toner is applied from the bias applying unit E52a to the bias roller 52a. A cleaning bias having the same polarity as the normal charging polarity of the toner is applied to the bias roller 52b from the bias applying means E52b. The opposing rollers 54a and 54b are rotationally driven in the forward direction with respect to the rotational direction of the belt 8.

  The above-described driving of the device 50 is performed while the belt 8 is driven to rotate. Residual toner on the surface of the belt 8 after the secondary transfer is conveyed to the apparatus 50 by the subsequent rotation of the belt, and first, toner of a normal charge polarity mainly electrostatically adheres from the belt 8 to the first fur brush 51a. It is removed and moves to the bias roller 52a. The toner adhering to the surface of the bias roller 52a is scraped off by the cleaning blade 53a. Next, the toner (reversed toner) whose charging polarity is reversed to the polarity opposite to the normal charging polarity is electrostatically adhered and removed from the belt 8 to the second fur brush 51b, and moves to the bias roller 52b. To do. The toner adhering to the surface of the bias roller 52b is scraped off into the apparatus housing 55 by the cleaning blade 53b.

  In this way, the residual toner on the surface of the belt 8 after the secondary transfer by the first and second fur brushes 51a and 51b of the apparatus 50 is effective for both the toner of the normal charge polarity and the reverse toner contained therein. Removed. That is, the secondary transfer residual toner on the belt surface is electrostatically adsorbed to the fur brush 51a51b to which a positive or negative cleaning bias is applied and cleaned from the belt surface, regardless of the charging polarity. The toner electrostatically attached to the first and second fur brushes 51a and 51b adheres to the respective bias rollers 52a and 52b and is scraped off into the apparatus housing 55 by the cleaning blades 53a and 53b. As a result, the cleaning performance does not deteriorate due to the increase in the toner adsorption amount of the fur brushes 51a and 51b.

(3-2) Second Cleaning Device The second cleaning device 60 is a device that further removes belt surface deposits that have not been removed by the first cleaning device 50. The belt surface deposit is mainly an external additive such as a charge control agent added to the toner or a paper filler. In addition, although it is a small amount, a toner that is not removed by the first cleaning device 50 is included. The second cleaning device 60 has a function of cleaning the web member by bringing it into contact with the belt 8, the web member is made of a non-conductive porous body, the surface is subjected to plasma discharge treatment, and the surface energy of the belt 8 is The hydrophilicity is set higher than that.

  The second cleaning device 60 in this embodiment will be described with reference to FIGS. The device 60 uses a non-woven cleaning web 61 as a non-conductive porous web member. The web 61 is a long roll roll attached to the attachment roller 62, is wound around the web roller 63, and is stretched around the take-up roller 64. The device 60 is disposed to face the belt winding portion of the driving roller 9 of the belt 8 and is controlled to move to an operating position and a non-operating position with respect to the belt 8. That is, the device 60 can be brought into contact with and separated from the belt 8. The operating position of the device 60 is such that the web 61 is in contact with the surface of the belt 8 with a predetermined pressing force at the belt winding portion of the driving roller 9 by the web roller 63 as shown in FIG. This is the position. The non-operating position of the device 60 is a position where the web 61 is separated from the surface of the belt 8 as shown in FIG. In this embodiment, the device 60 is supported and disposed so as to be swingable about a rotation center shaft 65 with respect to a device frame (mounting frame: not shown) of the device 100. Then, the device 60 is shifted between the operating position shown in FIG. 2A and the non-operating position shown in FIG. It is possible. The conversion of the device 60 to the non-operation position is to prevent a large amount of toner from being taken into the web 61 when untransferred and high-concentration toner is supplied when a paper jam occurs. The separation / contact means 66 may be driven using a motor in addition to the solenoid, and may be configured to be separated / contacted by parallel movement instead of rotation.

  In the state where the device 60 is changed to the working position, the surface of the belt 8 that is rotationally driven is rubbed by the web 61 so that the belt surface deposits that are not removed by the first cleaning device 50 are removed. Is done. The winding roller 64 is rotationally driven little by little continuously or intermittently in the direction of winding the web 61 by a driving means (not shown). Thereby, the web contact portion with respect to the belt 8 is sequentially updated to a new web surface.

  Here, as the web 61, conventionally, for example, one type or two or more types selected from polyester, acrylic, vinylon, water-soluble vinylon, rayon, nylon, polypropylene, cotton and the like are used. However, in the case of such a web, an external additive such as a charge control agent or a paper filler added to the toner on the belt surface that has not been removed by the first cleaning device 50, as in a comparative example described later. The removal efficiency is not high. Therefore, a considerable amount of these materials pass through the web, adhere to the belt 8, and accumulate as the image forming operation is repeated. This is because the conventional web is mainly composed of an oleophilic material such as polyester or polypropylene for the purpose of collecting toner that passes through the first cleaning device 50. Some toner external additives and paper fillers are hydrophilic and can slip through the web.

  Therefore, in this embodiment, the effect of improving the hydrophilicity of the surface of the cleaning web is obtained by performing plasma discharge treatment on the conventional cleaning web. By performing the plasma discharge treatment, the surface of the lipophilic synthetic fiber is hydrophilized. As a result, it is possible to increase the adsorbing force on the web 61 with respect to hydrophilic substances such as silica, titanium oxide, calcium carbonate, and talc, which are toner external additives and paper fillers, and prevent adhesion to the belt 8. It becomes possible to do. Further, by performing the plasma surface treatment, it is possible to improve the hydrophilicity of the fiber surface without selecting the material of the web, the thickness of the fiber, and the structure. Further, since the internal fiber of the web retains the conventional lipophilic nature of the fiber, the cleaning function of the residual toner on the belt, which is the original function, can be secured.

  The material of the web before the plasma discharge treatment may be a conventional web material. One type or two or more types selected from polyester, acrylic, vinylon, water-soluble vinylon, rayon, nylon, polypropylene, cotton and the like can be used. However, it is not limited to the above materials.

  As a specific configuration, by using a cleaning web having a higher hydrophilicity than the belt surface, the adsorbing force of the web with respect to a substance that slips through is increased to prevent adhesion to the belt. Therefore, as shown in FIG. 3, the contact angle (pure water) is compared, and the web contact angle is set lower than the contact angle of the belt 8. Since polyimide, which is a representative material of the belt 8, has a contact angle of about 50 °, it is desirable that the setting be smaller than this value, that is, less than 50 °. FIG. 4 is an explanatory diagram showing a method for measuring the contact angle. The contact angle is measured as follows. First, the sample surface S is set and fixed horizontally on the contact angle meter. Next, while observing the sample surface S on an enlarged screen, about 10 μg of reagent M, here pure water subjected to ion exchange treatment, is dropped onto the sample surface S using a dropper or syringe ((a)). Then, the contact angle θ shown in (b) is measured in a state where the dropped reagent M keeps its shape on the sample surface S due to surface tension. As the value of the contact angle θ is larger, the reagent M is less likely to remain on the sample surface S.

  Here, the cleaning web of this example uses a nonwoven fabric configuration, but the configuration is not particularly limited as long as it is a non-conductive porous body. In addition, various known methods can be adopted for the plasma discharge treatment. For example, a method using vacuum or low-pressure glow discharge, a method using atmospheric pressure corona discharge, a method using atmospheric pressure glow discharge, or a material to be processed is sandwiched between dielectrics, For example, a method using a discharge generated in an internal gap. Here, the treatment method can be carried out by generating a discharge in a surface treatment gas such as air, and the treatment method is not particularly limited as long as a gas capable of imparting hydrophilicity is used.

(4) Experiment Next, as a cleaning web 61 in the second cleaning device 60, using a typical web material, the results of comparing the cleaning properties of toner external additives and paper fillers with and without plasma discharge treatment. Will be described. In Comparative Example Sample 1 and Comparative Example Sample 2, the lipophilic material used in the conventional cleaning web was tested without plasma discharge treatment, and in Example Sample 1 and Example Sample 2, the above lipophilic material was used. The experiment was conducted using a material subjected to plasma discharge treatment. The belt to be cleaned used has a surface contact angle θ of about 90 to 100 °.

Comparative Example Sample 1: No Polypropylene Material Plasma Discharge Treatment Comparative Example Sample 2: No Acrylic Material Plasma Discharge Treatment Example Sample 1: Polypropylene Material Plasma Discharge Treatment Example Sample 2: Acrylic Material Plasma Discharge Processed member to be cleaned: Intermediate transfer belt surface contact angle about 90-100 °
In the experiment method, the actual product was used and the number of times of image formation was repeated, and the smear reflection density of the intermediate transfer belt gloss and the cleaning web at that time were compared. The results of the experiment are shown in Table 1 and FIG.

  When the comparative example sample 1 and the comparative example sample 2 were compared, the comparative example sample 2 showed a slower gloss reduction. Then, the hydrophilicity of the web surface is improved by plasma discharge treatment, and Example Sample 1 and Example Sample 2 having higher hydrophilicity than the belt 8 are less hydrophilic than Comparative Example Sample 1 and Comparative Example Sample 2. However, the gloss of the belt 8 did not decrease much, and good results were obtained. In FIG. 5A, it can be seen that the web having higher hydrophilicity than the belt 8 in the number of times of image formation has a gentle decrease in belt gloss compared to the web having lower hydrophilicity. This is because, as shown in (b), when the amount of dirt on the web when the same image is continuously formed with each sample is compared with the reflection density, the web having higher hydrophilicity shows a higher reflection density. Yes. From this result, it can be seen that the highly hydrophilic web adsorbs many substances, and it is proved that there is little slip-through from the web, and it can be judged that the effect of suppressing the belt gloss reduction is obtained.

  In this way, the surface of the intermediate transfer belt 8 can be reduced, and adhering substances such as toner external additives and recording material fillers can be effectively removed from the surface of the belt 8. This prevents the belt surface from lowering the glossiness caused by the adhering substance for a long period of time, and the position detection toner image formed on the belt 8 is read by the optical reading device 13 so that the rotational position of the belt 8 can be detected. It is possible to provide an image forming apparatus capable of performing detection for a long time.

[Example 2]
Next, Example 2 will be described. In the second embodiment, the basic configuration of the image forming apparatus is the same as that of the apparatus 100 of the first embodiment. In the first embodiment, the intermediate transfer belt 8 as the member to be cleaned has a surface contact angle θ of about 90 to 100 °, whereas in the second embodiment, the intermediate transfer belt 8 has a high hydrophilicity of about 50 °. It was used. The cleaning performance of the external additive of toner and the filler of paper according to the presence or absence of plasma discharge treatment between the belt 8 and a typical cleaning web material was compared.

Comparative Example Sample 1: No Polypropylene Material Plasma Discharge Treatment Comparative Example Sample 2: No Acrylic Material Plasma Discharge Treatment Example Sample 1: Polypropylene Material Plasma Discharge Treatment Example Sample 2: Acrylic Material Plasma Discharge Processed member to be cleaned: Intermediate transfer belt surface contact angle approx. 50 °
The results of the experiment are shown in Table 2 and FIG.

  Compared with Example 1, the gloss reduction of Comparative Example Sample 1 tended to occur from the early stage of image formation. However, as in Example 1, Example Sample 1 and Example Sample 2 having higher hydrophilicity have less decrease in gloss of the intermediate transfer belt than Comparative Example Sample 1 and Comparative Example Sample 2 having lower hydrophilicity. Good results were obtained. Also, the results shown in FIG. 6 are the same as those in Example 1, and in terms of the number of image formations, the cleaning web having high hydrophilicity has a gentle decrease in the gloss of the intermediate transfer belt compared with the cleaning web having low hydrophilicity. . Further, when the amount of dirt on the web when the same image is continuously formed with each sample is compared with the reflection density, the web having higher hydrophilicity shows a higher reflection density. From this result, it can be seen that the highly hydrophilic web adsorbs many substances, and it is proved that there is little slip-through from the web, and it can be determined that the effect of suppressing the gloss reduction of the belt 8 is obtained.

  In this way, the surface of the intermediate transfer belt 8 can be reduced, and adhering substances such as toner external additives and recording material fillers can be effectively removed from the surface of the belt 8. This prevents the belt surface from lowering the glossiness caused by the adhering substance for a long period of time, and the position detection toner image formed on the belt 8 is read by the optical reading device 13 so that the rotational position of the belt 8 can be detected. It is possible to provide an image forming apparatus capable of performing detection for a long time.

[Other matters]
1) In the embodiment, an elastic belt having an elastic layer is used as the intermediate transfer belt 8. However, even if the intermediate transfer belt 8 is a resin belt, the same effect can be obtained.

  2) In the present invention, the intermediate transfer member is not limited to the belt type of the embodiment. It can also be in the form of a rotatable drum.

  3) The image forming unit for primarily transferring the developer image to the intermediate transfer member is not limited to the electrophotographic image forming unit of the embodiment. An electrostatic recording image forming unit using an electrostatic recording dielectric as an image carrier, a magnetic recording image forming unit using a magnetic recording magnetic material as an image carrier, and the like may be used.

  4) The intermediate transfer member is not limited to an elastic intermediate transfer member having an elastic layer. A resin intermediate transfer member without an elastic layer may be used. In the case of the resin intermediate transfer member, a blade cleaning device having a contact load larger than that of the electrostatic fur brush cleaning device can be adopted as the first cleaning device 50.

  100..Image forming apparatus, PY.PM.PC.PK..Image forming unit, 8..Intermediate transfer member, T1..Primary transfer unit, T2 .... Secondary transfer unit, 50..First cleaning means, 60..Second cleaning means 61..Web member

Claims (6)

A developer image formed in an image forming unit having a rotatable intermediate transfer member is transferred to the intermediate transfer member in a primary transfer unit, and the developer image primarily transferred to the intermediate transfer member is secondary An image forming apparatus that performs secondary transfer on a recording material at a transfer unit,
The intermediate transfer member is disposed in order along the intermediate transfer member rotation direction downstream of the secondary transfer unit and upstream of the image forming unit with respect to the intermediate transfer member rotation direction, and cleans the surface of the intermediate transfer member. A cleaning means and a second cleaning means;
The second cleaning means has a function of cleaning the web member by bringing it into contact with the intermediate transfer body, the web member is made of a non-conductive porous body, and the surface is subjected to plasma discharge treatment so that the intermediate transfer is performed. An image forming apparatus characterized in that the hydrophilicity is set higher than the surface of a body.   The image forming apparatus according to claim 1, wherein the intermediate transfer member has an elastic layer and has a multilayer belt structure.   The image forming apparatus according to claim 1, wherein the web member has a contact angle with pure water set to less than 50 °.   4. The rotational position of the intermediate transfer member is detected by reading a developer image for position detection formed on the intermediate transfer member with an optical reader. The image forming apparatus according to one item.   The image forming apparatus according to claim 1, wherein the second cleaning unit is capable of contacting and separating from the intermediate transfer member.   6. The image forming apparatus according to claim 1, wherein the first cleaning unit has a function of cleaning an electrostatic fur brush in contact with the intermediate transfer member. apparatus.