JP2004240212A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a transfer belt from coming into contact with an image forming unit at the time of attaching/detaching the image forming unit or a transfer belt unit in an image forming apparatus which has an image carrier, the image forming unit to form a toner image on the image carrier and the transfer belt unit having the transfer belt to which the toner image formed on the image carrier is transferred and where the image forming unit and the transfer belt unit are attachably/detachably attached to an image forming apparatus main body. <P>SOLUTION: The image forming apparatus is provided with a belt holding body 63 to hold the transfer belt 3 at a position where it is separated from the image carrier 2BK at the time of attaching/detaching the image forming units 40 and 140 or the transfer belt unit 39. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image carrier, an image forming apparatus for forming a toner image on the image carrier, and a transfer belt having a transfer belt for transferring a toner image formed on the image carrier to a recording medium. Unit, and one or more of the image carrier and the image forming apparatus are configured as an image forming unit, and the image forming unit and the transfer belt unit are arranged with respect to an image forming apparatus main body. The present invention relates to an image forming apparatus detachably mounted.
[0002]
[Prior art]
An image forming apparatus of the above type configured as a copier, a printer, a facsimile, or a multifunction machine having at least two of these functions has been conventionally known. In this type of image forming apparatus, one or more of the image carrier and the image forming apparatus are configured as an image forming unit that can be attached to and detached from the image forming apparatus main body. Since it can be attached to and detached from the main body of the image forming apparatus, not only a service person who specializes in maintenance of the image forming apparatus, but also a general user can easily inspect, repair or replace the image carrier and the image forming apparatus. It is possible to do.
[0003]
However, even though the operation is easy, if an unskilled user attaches or detaches the image forming unit or the transfer belt unit, the image forming unit is brought into contact with the transfer belt or rubbed against the transfer belt. There is a danger of scratching and shortening its life.
[0004]
Therefore, an image forming apparatus has been proposed in which the transfer belt is configured to be able to be separated from the image forming unit, and the image forming unit or the transfer belt unit is configured to be detachable after separating the two (for example, Patent Documents). 1). However, if the transfer belt vibrates due to external force applied to the transfer belt when the image forming unit or the transfer belt unit is attached or detached, the transfer belt may come into contact with the image forming unit. Therefore, it is conceivable to configure the transfer belt so that it can be largely separated from the image forming unit.However, in this case, a large space in which the two can relatively move must be secured in the image forming apparatus main body. The disadvantage that the image forming apparatus body becomes large is inevitable.
[0005]
[Patent Document 1]
JP-A-9-325622 (paragraphs [0036], [0038], FIG. 3)
[0006]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus of the type described at the beginning, which can eliminate the above-mentioned conventional disadvantages.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides an image forming apparatus of the type described at the beginning, wherein the belt for holding the transfer belt at a position separated from the image forming unit when the image forming unit or the transfer belt unit is attached or detached. An image forming apparatus provided with a position regulating means is proposed (claim 1).
[0008]
In the image forming apparatus according to the first aspect, it is advantageous that the belt position regulating unit is provided in the transfer belt unit (claim 2).
[0009]
Further, in the image forming apparatus according to claim 1 or 2, the belt position regulating means includes an oscillating member oscillatably supported with respect to the transfer belt unit, and a belt holding member provided on the oscillating member. The belt holding member is configured to hold the transfer belt at a position separated from the image forming unit by swinging the rocking member in a direction away from the image forming unit. It is advantageous (claim 3).
[0010]
Further, in the image forming apparatus according to any one of claims 1 to 3, it is advantageous that the belt position regulating means is engaged with the image forming unit when the image forming unit or the transfer belt unit is attached or detached. (Claim 4).
[0011]
Furthermore, in the image forming apparatus according to any one of claims 1 to 4, it is advantageous that the image forming unit includes a developing device that visualizes a latent image formed on the image carrier as a toner image. (Claim 5).
[0012]
Further, in the image forming apparatus according to any one of claims 1 to 5, it is advantageous that the image forming unit includes a cleaning device that cleans the surface of the image carrier after the transfer of the toner image (claim 6). .
[0013]
5. The image forming apparatus according to claim 1, wherein the image forming unit includes an image carrier, and at least one image forming device for forming a toner image on the image carrier. It is advantageous that the process cartridge has the following.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0015]
FIG. 1 is a vertical sectional view showing an example of an image forming apparatus for forming a full-color image. The image forming apparatus shown in FIG. The image forming apparatus includes fourth image carriers 2Y, 2C, 2M, and 2BK, and an endless transfer belt 3 similarly arranged in the image forming apparatus main body 1. The transfer belt 3 is wound around support rollers 4, 5, and 6, and is rotationally driven in the direction of arrow A. The transfer belt 3 is in contact with each of the image carriers 2Y to 2BK, and the toner images of each color formed on each image carrier are transferred onto the transfer belt in a superimposed manner. That is, first, the yellow toner image formed on the first image carrier 2Y starts to be transferred onto the transfer belt 3, and the cyan toner image formed on the second image carrier 2C is superimposed and transferred from above. Then, the magenta toner image formed on the third image carrier 2M is transferred from above, and the black toner image formed on the fourth image carrier 2BK is further transferred from above. .
[0016]
The configuration in which a toner image is formed on each of the first to fourth image carriers 2Y, 2C, 2M, and 2BK and the toner image is transferred to the transfer belt 3 is substantially different only in the color of the toner image. Here, only the configuration in which a toner image is formed on the fourth image carrier 2BK and the toner image is transferred to the transfer belt 3 will be described. FIG. 4 is an enlarged view showing the image carrier 2BK and image forming devices provided around the image carrier 2BK. The image carrier 2BK is rotated clockwise in FIG. 4, and at this time, the image carrier 2BK is charged to a predetermined polarity by a charging device including a charging roller 7 to which a charging voltage is applied. A cleaning roller 30 for cleaning the surface of the charging roller 7 is in contact with the charging roller 7. The charged image carrier 2BK is irradiated with a light-modulated laser beam L emitted from the optical writing device 8 (see FIG. 1), whereby an electrostatic latent image is formed on the image carrier 2BK. This electrostatic latent image is visualized as a black toner image by the developing device 9.
[0017]
The optical writing device 8 has a well-known configuration in which an optical element such as a laser light source, a rotating polygon mirror, and an F / θ lens (not shown) is accommodated in the case 50, and is formed in the case 50. The laser beam L is emitted from the light emission port 51. An optical writing device using a light emitting diode can also be used. In both types of optical writing devices, the charged image carrier is irradiated with light to expose the image carrier and form a latent image on the image carrier.
[0018]
As shown in FIG. 4, the developing device 9 includes a developing case 10 containing a dry type developer D, a rotatable supporting member for the developing case 10, and an image carrier 2BK through an opening formed in the developing case. The developing roller 11 is disposed close to the developing roller 11, the developing blade 31 regulates the amount of developer on the developing roller 11, and the first and second transport screws 32, 33 disposed facing the developing roller 11 are Have. The developer D in the developing case 10 is stirred while being transported by the first and second transport screws 32 and 33, and is transported while being carried on the developing roller 11 rotating in the direction of the arrow. At this time, the height of the developer on the developing roller 11 is regulated to be constant by the developing blade 31, and the regulated developer is carried to a developing area between the developing roller 11 and the image carrier 2BK. The toner in the agent electrostatically transfers to the electrostatic latent image formed on the image carrier, and the latent image is visualized as a toner image. As the developer, either a one-component developer or a two-component developer can be used. Here, a two-component developer having a toner and a carrier is used.
[0019]
A primary transfer roller 12BK is disposed on the opposite side of the image carrier 2BK with the transfer belt 3 interposed therebetween. When a transfer voltage is applied to the primary transfer roller 12BK, the toner image on the image carrier 2BK is turned into an arrow A The primary transfer is performed on the transfer belt 3 rotating in the direction. The transfer residual toner adhering to the image carrier 2BK after the transfer of the toner image is removed by the cleaning device 13.
[0020]
The cleaning device 13 of this example has a cleaning case 34 having an opening on the side facing the image carrier 2BK, a base end portion fixedly supported by the cleaning case 34, and a front end portion pressed against the surface of the image carrier 2BK. A cleaning blade 35 for removing the transfer residual toner on the image carrier 2BK; and a waste toner transport screw 36 for transporting the removed toner to a waste toner bottle (not shown). Since a charging voltage in which an AC component is superimposed on a direct current is applied to the charging roller 7, when the image carrier 2 </ b> BK passing through the cleaning device 13 passes through the charging roller 7, the image carrier 2 </ b> BK is charged at the same time as static elimination, so Prepare for the image.
[0021]
The configuration in which the black toner image is formed on the fourth image carrier 2BK and the toner image is transferred to the transfer belt 3 has been described above. A yellow toner image, a cyan toner image, and a magenta toner image are also formed on the third image carriers 2Y, 2C, and 2M, respectively, and these toner images and the fourth image carrier 2BK are formed as described above. The primary toner images are sequentially transferred onto the transfer belt 3 in such a manner that the black toner images thus obtained are superimposed on each other, and a synthetic toner image is formed on the transfer belt 3. The transfer residual toner on each of the image carriers 2Y, 2C, and 2M after the transfer of the toner image is removed by the cleaning device as in the case of the fourth image carrier 2BK. As shown in FIG. 1, an image forming apparatus that operates similarly to the image forming apparatuses provided around the first to third image carriers 2Y, 2C, and 2M around the fourth image carrier 2BK is also provided. Although they are arranged, their description is omitted. However, in FIG. 1, reference numerals 12Y, 12C, and 12M are assigned to respective primary transfer rollers for transferring the toner images on the image carriers 2Y, 2C, and 2M to the transfer belt 3, respectively.
[0022]
On the other hand, as shown in FIG. 1, a paper feed cassette 14 containing a recording medium P made of, for example, transfer paper, and a paper feed device 16 having a paper feed roller 15 are arranged in a lower portion inside the image forming apparatus main body 1. The uppermost recording medium P is fed in the direction of arrow B by the rotation of the paper feed roller 15. The fed recording medium is fed by a pair of registration rollers 17 between a portion of the transfer belt 3 wound around the support roller 4 at a predetermined timing and a secondary transfer roller 18 opposed thereto. . At this time, a predetermined transfer voltage is applied to the secondary transfer roller 18, whereby the composite toner image on the transfer belt 3 is secondarily transferred to the recording medium P.
[0023]
The recording medium on which the composite toner image has been secondarily transferred is further conveyed upward and passes through a fixing device 19, where the toner image on the recording medium is fixed by the action of heat and pressure. The recording medium that has passed through the fixing device 19 is discharged by a paper discharge roller pair 20 to a paper discharge unit 22 at an upper portion of the image forming apparatus main body 1. Further, the transfer residual toner adhered to the transfer belt 3 after the transfer of the toner image is removed by the cleaning device 24.
[0024]
Toner bottles 37Y, 37C, 37M and 37BK containing toners of yellow, cyan, magenta and black are arranged in the upper part of the image forming apparatus main body 1, and the toner of each color is drawn from each toner bottle. Each developing device is replenished through a transport path not shown.
[0025]
The transfer belt 3 is housed in a belt casing 38 as shown in FIG. 1, and the primary transfer rollers 12Y, 12C, 12M, and 12BK, and the support rollers 4, 5, and 6 are disposed on the front and rear side plates 38A, 38B (see FIG. 5) is rotatably supported via a bearing, and the cleaning device 24 is also assembled to the belt casing 38. At this time, as shown in FIG. 5, the primary transfer roller 12BK moves toward and away from the image carrier 2BK in elongated holes 52A and 52B formed in the front and rear side plates 38A and 38B of the belt casing 38. It is fitted movably. Although not shown, the other primary transfer rollers 12Y, 12C, and 12M are also supported.
[0026]
In the image forming apparatus of the present embodiment, the transfer belt 3, the belt casing 38, the primary transfer rollers 12Y to 12BK, the support rollers 4, 5, 6, and the cleaning device 24 constitute an integral transfer belt unit 39. The components of the transfer belt unit can be appropriately selected. In short, the transfer belt unit has a transfer belt for transferring a toner image formed on an image carrier to a recording medium. The transfer belt unit 39 is pulled out in the front side of the image forming apparatus main body 1, that is, in the front direction perpendicular to the paper surface of FIG. The image forming apparatus 1 is supported by the image forming apparatus main body 1 so as to be detachable from the image forming apparatus 1.
[0027]
The illustrated image forming apparatus is configured to transfer the toner image formed on each image carrier to the transfer belt 3 and transfer the toner image on the transfer belt to a recording medium. It is also possible to adopt a configuration in which the toner image formed on the image carrier is transferred onto the recording medium while being carried on a transfer belt. In this case, the toner image is not transferred to the transfer belt, and the toner image is directly transferred to the recording medium carried on the transfer belt. This transfer belt is also for transferring the toner image formed on the image carrier to a recording medium, and a transfer belt unit can be constituted by such a transfer belt in the same manner as described above.
[0028]
In the image forming apparatus shown in FIG. 1, all the image carriers 2Y to 2BK contact the surface of the transfer belt 3 when a full-color image is formed. At the standby time when the transfer is not performed, as shown in FIG. 2, the portion of the transfer belt 3 facing the first to third image carriers 2Y, 2C, 2M and the primary transfer rollers 12Y, 12C, 12M moves in a direction away from the image carriers 2Y, 2C, and 2M, and the transfer belt 3 is separated from these image carriers 2Y, 2C, and 2M.
[0029]
When the above-described transfer belt unit 39 or an image forming unit described later is attached to or detached from the image forming apparatus main body 1, as shown in FIG. 3, the transfer belt portion facing the image carrier 2BK and the primary transfer roller 12BK also moves in a direction away from the image carrier 2BK, and the transfer belt 3 separates from all the image carriers 2Y to 2BK.
[0030]
The charging device including the charging roller 7, the optical writing device 8, the developing device 9, and the cleaning device 13 shown in FIG. 4 constitute an image forming device for forming a toner image on the image carrier 2BK. The same applies to the charging roller, the developing device, and the cleaning device provided around the other image carriers 2Y, 2C, and 2M. As described above, the image forming apparatus of the present example has the image forming device for forming the toner image on the image carrier.
[0031]
Here, one or more of the image carrier and one of the above-described image forming apparatuses are integrated with the image forming apparatus main body 1 as an integral image forming unit that is detachable in the axial direction of the image carrier. It is configured. For example, an image forming unit is constituted by one image carrier and a support for supporting the image carrier, or an image forming unit is constituted by one charging device and a support for supporting the same. Further, the image forming unit may be constituted by one developing device alone or one cleaning device alone, or the image forming unit may be constituted by assembling the developing device and the image carrier. Alternatively, the image forming unit can be constructed by assembling the charging device or by assembling the charging device respectively. As described above, an image forming unit can be configured by appropriately combining one or more of the image forming apparatus and the image carrier, but FIG. The cleaning device 13 and the image carrier 2BK are assembled, and the charging roller 7 and the cleaning roller 30 are rotatably supported by the cleaning case 34 of the cleaning device 13 so that another image forming unit 140 is formed. Is shown. It is assumed that a similar image forming unit is constituted by the other image carriers 2Y, 2C, and 2M and the image forming devices provided therearound.
[0032]
Each of the image forming units 40 and 140 described above is detachably attached to the image forming apparatus main body 1 in the axial direction of the image carrier, that is, in the same direction as the attaching and detaching direction of the transfer belt unit 39. When the image forming units 40 and 140 are attached and detached, these units 40 and 140 are guided by the case 50 of the optical writing device 8. As described above, since the image forming unit and the transfer belt unit are detachably attached to the main body of the image forming apparatus, when these units 39, 40, and 140 are inspected, repaired, or replaced. Each unit 39, 40, 140 can be pulled out to the front side of the image forming apparatus main body 1, or each unit can be pushed into the back side of the image forming apparatus main body 1. When each of the units 39, 40, and 140 is attached to and detached from the image forming apparatus main body 1, the elements of the units 39, 40, and 140 come into contact with each other, and particularly, the image carriers 2Y to 2BK are attached to the transfer belt 3. If hit or rubbed heavily, they will be damaged and shorten the life of parts that need not be replaced yet.
[0033]
Thus, in the image forming apparatus of this embodiment, the transfer belt 3 is separated from the image carriers 2Y to 2BK as described above when the transfer belt unit 39 and the image forming units 40 and 140 are attached and detached. With this configuration alone, any external force is applied to the transfer belt 3 when these units 39, 40, and 140 are attached and detached, and the transfer belt 3 moves due to vibration or the like. May come into contact with the image forming unit, particularly the image carrier, and these may be damaged.
[0034]
In order to prevent the above-described problem, the image forming apparatus of the present embodiment has a belt position regulation that holds the transfer belt at a position separated from the image forming unit when the image forming unit or the transfer belt unit is attached to or detached from the image forming apparatus main body. Means are provided.
[0035]
The configuration and operation of the belt position regulating means 60 will be described below with reference to FIGS. The belt position regulating means 60 has an oscillating body 62 oscillatably supported via a bearing 61 on a shaft portion of the support roller 6 for the transfer belt 3. The end 63A is fixed. The belt holder 63 extends in the width direction of the transfer belt 3, and the transfer belt 3 is located between the belt holder 63 and the swinging member 62. Further, the above-described primary transfer roller 12BK is rotatably supported by the rocking member 62. Further, the oscillating body 62 is urged by a tension spring 64 in a direction away from the image carrier 2BK, and is pressed by a cam 65. The cam 65 is fixed to a shaft 66, which is rotatably supported via bearings on front and rear side plates 38A and 38B of a belt casing 38 of the transfer belt unit 39, though not shown. A handle 67 is fixed to the front end of the shaft 66.
[0036]
When the image forming operation is performed as described above, as shown in FIG. 4, the large diameter portion 65 </ b> A of the cam 65 presses against the rocking body 62 and presses the rocking body 62 against the action of the tension spring 64. . As a result, the primary transfer roller 12BK comes into pressure contact with the image carrier 2BK via the transfer belt 3. At this time, neither the swinging member 62 nor the belt holding member 63 comes into contact with the transfer belt 3.
[0037]
When taking out the image forming units 40 and 140 or the transfer belt unit 39 from the image forming apparatus main body 1, the handle 67 is rotated in the direction of arrow C in FIG. Let it. As a result, the swinging member 62 is pulled by the tension spring 64 and swings around the central axis of the support roller 6 in the direction of arrow E, and as shown in FIG. At the same time, the belt holding member 63 lifts the transfer belt 3 and holds the transfer belt 3 at a position separated from the image forming units 40 and 140, in particular, the image carrier 2BK. In this state, since the image forming units 40 and 140 or the transfer belt unit 39 is attached to and detached from the image forming apparatus main body 1, even if the transfer belt 3 moves due to vibration or the like at the time of attachment or detachment, the transfer belt 3 Can be prevented from contacting the image forming units 40 and 140. After the image forming unit or the transfer belt unit is set in the image forming apparatus main body again, by rotating the handle 67 in the direction opposite to the arrow C, the primary transfer roller 12BK is transferred to the image carrier 2BK via the transfer belt 3. It can be pressed.
[0038]
When the rocking body 62 is in the state shown in FIG. 4, the image forming units 40 and 140 and the transfer belt unit 39 cannot be pulled out of the image forming apparatus main body 1 by a lock device (not shown). When these units 39, 40, and 140 are locked and the swinging body 62 is rotated to the position shown in FIG. 7, the lock of the locking device is released, and the units 39, 40, and 140 are removed from the image forming apparatus main body 1. If the units 39, 40, and 140 are configured so that they can be pulled out, the transfer belt 3 is always held at a position separated from the image forming units 40 and 140 by the belt holder 63 when the units 39, 40, and 140 are attached and detached. The problem that 39, 40 and 140 interfere with each other and damage them can be more reliably prevented.
[0039]
The belt holder 63 is formed of, for example, resin or sheet metal. If the belt holder facing the transfer belt 3 is subjected to flocking 70 as shown in FIG. As shown, when the belt holder 63 contacts the transfer belt 3, it is possible to prevent the transfer belt 3 from being damaged. Further, the belt holder 63 may be formed of a round bar, and when such a belt holder 63 contacts the transfer belt, it is possible to more reliably prevent the transfer belt 3 from being damaged. be able to.
[0040]
As described above, the belt position regulating unit 60 of the present example is provided in the transfer belt unit 39, and the belt position regulating unit 60 includes the swinging body 62 that is swingably supported with respect to the transfer belt unit 39. And a belt holder 63 provided on the oscillating body 62, and by oscillating the oscillating body 62 in a direction away from the image forming units 40 and 140, the belt holding body 63 forms an image of the transfer belt 3. It is configured to be held at a position separated from the units 40 and 140.
[0041]
Further, the belt position regulating means may be configured to engage with the image forming unit when the image forming unit or the transfer belt unit is attached to and detached from the image forming apparatus main body. 8 and 9 show an example. When the image forming units 40 and 140 and the transfer belt unit 39 are set at predetermined positions in the main body of the image forming apparatus, as shown in FIGS. 8 and 9, the image forming does not interfere with the belt holder 63. A pair of guide portions 71A and 71B are provided to project from the unit portion. As shown in FIG. 8, after the swinging member 62 is rotated to hold the transfer belt 3 at a position separated from the image forming units 40 and 140 by the belt holding member 63, the transfer belt 3 is formed as shown by the arrow X in FIG. When the image unit 140 is pulled out toward the near side of the image forming apparatus main body, the guide portion 71B on the back side engages with the belt holding member 63 and rubs as shown in FIG. The same applies when the image forming unit 140 is set by being pushed into the image forming apparatus main body. When the transfer belt unit 39 is pulled out in the direction indicated by the arrow X in FIG. 9 or pushed in the opposite direction, the belt holder 63 moves together with the transfer belt unit 39. Rubs against the guide portion 71A on the front side. In this manner, when the image forming unit 140 or the transfer belt unit 39 is attached or detached, the belt position restricting means 60, in the illustrated example, the belt holder 63 is configured to engage with the guide portions 71A and 71B of the image forming unit 140. In addition, when the units 39 and 140 are attached and detached, the interval between the units 39 and 140 can be reliably maintained, and the interference between them can be more reliably prevented.
[0042]
In addition, as shown in FIGS. 4 and 6 to 9, the rocking member 62 is provided with another belt holding member 163 having the same function as the belt holding member 63, and as shown in FIG. Also, a pair of guide portions 171A and 171B can be provided, and the guide portions 171A and 171B can be engaged with the belt holder 163 when the image forming unit 40 or the transfer belt unit 39 is attached or detached.
[0043]
By providing the above-described guide portions 71A, 71B, 171A, 171B integrally with the image forming unit, it is possible to prevent an increase in the number of components of the image forming apparatus. Further, when the image forming unit is pulled out of the image forming apparatus main body, a shutter (not shown) for covering the image carrier can be provided, but a guide portion can be integrally provided with the shutter.
[0044]
In the example described above, one image forming unit 40 includes the developing device 9 that visualizes a latent image formed on the image carrier as a toner image, and the other image forming unit 140 includes the toner image. It has a cleaning device 13 for cleaning the surface of the image carrier after the transfer. At this time, an image forming unit having an image carrier and at least one image forming device for forming a toner image on the image carrier, such as the latter image forming unit, is particularly referred to as a process cartridge. Then, the process cartridge can be configured in various forms other than the image forming unit 140. For example, a unit case is formed by integrating the developing case 10 and the cleaning case 34, and the developing device 9, the cleaning device 13, the charging roller 7, and the cleaning roller 30 are integrally assembled to form a process cartridge. You can also. Also in this case, when the process cartridge or the transfer belt unit is attached or detached, the transfer belt can be held at a position separated from the process cartridge by the belt position regulating means.
[0045]
In the above-described image forming apparatus, one belt position regulating unit 60 is configured to hold the transfer belt 3 at a position separated from each image forming unit. However, a plurality of belt position regulating units may be provided. Thereby, the transfer belt can be more reliably held at a position away from each image forming unit.
[0046]
In addition, as a charging device for charging the image carrier, a charging device of a corotron type can be used in addition to a charging roller that is in contact with or close to the image carrier. Further, as the developing bias applied to the developing roller 11 of the developing device 9, in addition to a DC voltage, a bias obtained by superimposing an AC voltage on a DC voltage may be used. As a transfer device for transferring an image, a conductive brush or the like may be used. Further, as a cleaning device for cleaning the image carrier, a device using a cleaning brush may be employed.
[0047]
Further, as the transfer belt 3, a belt made of a fluorine-based resin, a polycarbonate resin, a polyimide resin, or the like can be used, but an elastic belt in which all layers of the belt or a part of the belt is an elastic member can also be used. For example, as shown in FIG. 10, a transfer belt 3 having a resin layer 3A, an elastic layer 3B, and a surface layer 3C can be used. Of course, a single-layer belt or an inelastic belt may be used.
[0048]
Here, as the resin layer 3A, polycarbonate, fluororesin (ETFE, PVDF), polystyrene, chloropolystyrene, poly-α-methylstyrene, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-acetic acid Vinyl copolymer, styrene-maleic acid copolymer, styrene-acrylate copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene -Octyl acrylate copolymer and styrene-phenyl acrylate copolymer), styrene-methacrylic ester copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-methacrylic acid) Phenyl copolymer), styrene-α-chloro Styrene-based resins (monopolymers or copolymers containing styrene or styrene substituents) such as methyl acrylate copolymer, styrene-acrylonitrile-acrylate copolymer, methyl methacrylate resin, butyl methacrylate resin, acrylic Ethyl acid resin, butyl acrylate resin, modified acrylic resin (silicone modified acrylic resin, vinyl chloride resin modified acrylic resin, acrylic / urethane resin, etc.), vinyl chloride resin, styrene-vinyl acetate copolymer, vinyl chloride-vinyl acetate copolymer Polymer, rosin-modified maleic resin, phenolic resin, epoxy resin, polyester resin, polyester polyurethane resin, polyethylene, polypropylene, polybutadiene, polyvinylidene chloride, ionomer resin, polyurethane resin, silicone resin, ketone Butter, ethylene - can be used ethyl acrylate copolymer, xylene resin and polyvinyl butyral resin, polyamide resin, one kind or two kinds or more selected from the group consisting of modified polyphenylene oxide resin. However, it is a matter of course that the material is not limited to the above.
[0049]
As the elastic material rubber and elastomer of the elastic layer 3B, butyl rubber, fluorine rubber, acrylic rubber, EPDM, NBR, acrylonitrile-butadiene-styrene rubber natural rubber, isoprene rubber, styrene-butadiene rubber, butadiene rubber, ethylene-propylene rubber , Ethylene-propylene terpolymer, chloroprene rubber, chlorosulfonated polyethylene, chlorinated polyethylene, urethane rubber, syndiotactic 1,2-polybutadiene, epichlorohydrin rubber, silicone rubber, fluorine rubber, polysulfide rubber, polynorbornene rubber , Hydrogenated nitrile rubber, thermoplastic elastomer (for example, polystyrene, polyolefin, polyvinyl chloride, polyurethane, polyamide, polyurea, polyester, fluororesin), etc. It is possible to use one kind or two kinds or more selected from the group. However, it is a matter of course that the material is not limited to the above.
[0050]
The conductive agent for adjusting the resistance value added to each layer of the transfer belt 3 is not particularly limited. For example, carbon black, graphite, metal powder such as aluminum and nickel, tin oxide, titanium oxide, antimony oxide, indium oxide, titanic acid Conductive metal oxides such as potassium, antimony oxide-tin oxide composite oxide (ATO), indium oxide-tin oxide composite oxide (ITO), and conductive metal oxides include barium sulfate, magnesium silicate, calcium carbonate, etc. May be coated with the above insulating fine particles. Naturally, the conductive agent is not limited to the above.
[0051]
There is no limitation on the material of the surface layer 3C, but one or two or more of polyurethane, polyester, epoxy resin, etc., which are required to reduce the adhesion of the toner to the surface of the transfer belt to enhance the secondary transferability, are required. One or more kinds of powders and particles, such as fluororesins, fluorine compounds, fluorocarbons, titanium dioxide, silicon carbide, etc., or different diameters, which are used to reduce surface energy and enhance lubricity. Things can be dispersed and used. Further, it is also possible to use a material obtained by performing a heat treatment such as a fluorine-based rubber material to form a fluorine-rich layer on the surface and reduce the surface energy.
[0052]
The method for manufacturing the belt is not limited. A centrifugal molding method in which a material is poured into a rotating cylindrical mold to form a belt, a spray coating method in which a thin film of the surface layer is formed, a dipping method in which a cylindrical mold is dipped into a material solution and pulled up, an inner mold, and an outer mold There is a casting method of injecting into a mold, a method of wrapping a compound around a cylindrical mold, and a method of performing vulcanization polishing, but the method is not limited to this, and a belt can be manufactured by combining a plurality of manufacturing methods. It is natural.
[0053]
A method for manufacturing the elastic belt used in this example will be described.
A cylindrical mold is immersed in a dispersion liquid in which 18 parts by weight of carbon black, 3 parts by weight of a dispersant, and 400 parts by weight of toluene are uniformly dispersed with respect to 100 parts by weight of PVDF, gently lifted at 10 mm / sec, and dried at room temperature. A uniform film of 75 μm PVDF was formed. The mold in which a 75 μm film was formed was repeated, and the cylindrical mold was immersed in the solution under the above conditions, gently pulled up at 10 mm / sec, and dried at room temperature to form a 150 μm PVDF belt. A cylinder in which the above-mentioned 150 μm PVDF is formed in a dispersion obtained by uniformly dispersing 100 parts by weight of a polyurethane prepolymer, 3 parts by weight of a curing agent (isocyanate), 20 parts by weight of carbon black, 3 parts by weight of a dispersant, and 500 parts by weight of MEK. The mold was immersed, pulled up at 30 mm / sec, and air-dried. After drying, repetition was performed to form a target urethane polymer layer of 150 μm. Further, 100 parts by weight of a polyurethane prepolymer, 3 parts by weight of a curing agent (isocyanate), 50 parts by weight of PTFE fine powder, 4 parts by weight of a dispersant, and 500 parts by weight of MEK were uniformly dispersed for the surface layer.
[0054]
The cylindrical mold on which the urethane prepolymer of 150 μm was formed was immersed, pulled up at 30 mm / sec, and air-dried. After drying, the repetition was performed to form a urethane polymer surface layer in which 5 μm of PTFE was uniformly dispersed. After drying at room temperature, crosslinking was performed at 130 ° C. for 2 hours to obtain a three-layer transfer belt having a resin layer of 150 μm, an elastic layer of 150 μm, and a surface layer of 5 μm.
[0055]
Examples of a method for preventing elongation as an elastic belt include a method of forming a rubber layer on a core resin layer having low elongation as in the above-described embodiment and a method of adding a material for preventing elongation to the core layer. It does not concern you. Materials constituting the core layer for preventing elongation include, for example, natural fibers such as cotton and silk, polyester fibers, nylon fibers, acrylic fibers, polyolefin fibers, polyvinyl alcohol fibers, polyvinyl chloride fibers, polyvinylidene chloride fibers, One or two selected from the group consisting of synthetic fibers such as polyurethane fibers, polyacetal fibers, polyfluoroethylene fibers, and phenol fibers; inorganic fibers such as carbon fibers, glass fibers, and boron fibers; and metal fibers such as iron fibers and copper fibers. A woven or thread-like material can be obtained by using more than one kind. Of course, it is not limited to the above materials.
[0056]
The yarn may be of any kind, such as twisted one or more filaments, single twisted yarn, multiple twisted yarn, twin yarn and the like. Further, for example, fibers of a material selected from the above material group may be blended. Of course, the yarn can be used after being subjected to an appropriate conductive treatment. On the other hand, as the woven fabric, any woven fabric such as a knitted woven fabric can be used. Needless to say, a woven fabric obtained by cross-weaving can also be used, and naturally a conductive treatment can be applied.
[0057]
The manufacturing method for providing the core layer is not particularly limited. For example, a method in which a woven fabric woven in a cylindrical shape is covered with a mold or the like, and a coating layer is provided thereon, and the woven fabric woven in a cylindrical shape is immersed in liquid rubber or the like to form a coating layer on one or both surfaces of the core layer. There may be mentioned a method of providing, a method of spirally winding a yarn around a mold or the like at an arbitrary pitch, and providing a coating layer thereon.
[0058]
The thickness of the elastic layer depends on the hardness of the elastic layer, but if it is too thick, the expansion and contraction of the surface becomes large and cracks easily occur in the surface layer. Further, it is not preferable that the thickness is too large (about 1 mm or more) because the amount of expansion and contraction becomes large and the image expands and bleeds. The appropriate range of the hardness of the elastic layer is 10 ≦ HS ≦ 65 ° (JIS-A). Adjustment of the optimum hardness is necessary depending on the layer thickness of the belt. It is very difficult to mold a material having a hardness of less than 10 ° JIS-A with high dimensional accuracy. This is due to the fact that it is liable to contract and expand during molding. In the case of softening, it is a general method to add an oil component to the base material, but there is a drawback that the oil component oozes out when continuously operated in a pressurized state. As a result, it was found that the photoreceptor in contact with the surface of the intermediate transfer member was contaminated and horizontal band-like unevenness was generated. Generally, a surface layer is provided to improve mold release properties, but in order to provide a complete leaching prevention effect, the surface layer must be of high required quality, such as durability quality. It becomes difficult. On the other hand, those having a hardness of 65 ° JIS-A or more can be molded with high precision because of the increased hardness, and can contain no or reduce the oil content, thereby reducing contamination to the photoreceptor. Although it is possible, it is not possible to obtain the effect of improving the transferability, such as missing characters, and it is difficult to stretch the roller.
[0059]
Although the example in which the present invention is applied to the image forming apparatus having a plurality of image carriers has been described above, the present invention can also be applied to an image forming apparatus having one image carrier.
[0060]
【The invention's effect】
According to the present invention, it is possible to prevent a problem that the transfer belt comes into contact with the image forming unit when the image forming unit or the transfer belt unit is attached or detached.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view of an image forming apparatus.
FIG. 2 is a cross-sectional view similar to FIG. 1, showing a state in which a transfer belt is separated from an image carrier other than an image carrier on which a black toner image is formed.
FIG. 3 is a sectional view similar to FIG. 1, showing a state in which a transfer belt is separated from all image carriers.
FIG. 4 is an enlarged cross-sectional view of a fourth image carrier and an image forming device provided around the fourth image carrier.
FIG. 5 is a sectional view taken along line VV of FIG. 4;
FIG. 6 is a perspective view of a belt position regulating unit.
FIG. 7 is a cross-sectional view similar to FIG. 4, showing a state where the transfer belt is held at a position separated from the image forming unit by a belt position regulating unit.
FIG. 8 is a sectional view similar to FIG. 7, illustrating an example in which a guide unit is provided in the image forming unit.
FIG. 9 is a schematic sectional view taken along line IX-IX of FIG.
FIG. 10 is an enlarged sectional view of a transfer belt.
[Explanation of symbols]
1 Image forming apparatus main body
2Y, 2C, 2M, 2BK Image carrier
3 Transfer belt
9 Developing device
13 Cleaning device
39 Transfer belt unit
40,140 Imaging unit
60 Belt position regulating means
62 rocking body
63 Belt holder
P Recording medium

Claims (7)

An image carrier, an image forming apparatus for forming a toner image on the image carrier, and a transfer belt unit having a transfer belt for transferring the toner image formed on the image carrier to a recording medium One or more of the image carrier and the image forming apparatus are configured as an image forming unit, and the image forming unit and the transfer belt unit are detachably attached to an image forming apparatus main body. In the image forming apparatus to be mounted,
An image forming apparatus comprising: a belt position regulating unit that holds the transfer belt at a position separated from the image forming unit when the image forming unit or the transfer belt unit is attached or detached. The image forming apparatus according to claim 1, wherein the belt position regulating unit is provided in the transfer belt unit. The belt position regulating means has an oscillating body supported oscillatably with respect to the transfer belt unit, and a belt holder provided on the oscillating body, and separates the oscillating body from the image forming unit. The image forming apparatus according to claim 1, wherein the belt holding member holds the transfer belt at a position separated from the image forming unit by swinging the transfer belt in a direction in which the transfer belt moves. 4. The image forming apparatus according to claim 1, wherein the belt position regulating unit engages with the image forming unit when the image forming unit or the transfer belt unit is attached or detached. The image forming apparatus according to claim 1, wherein the image forming unit includes a developing device that visualizes a latent image formed on the image carrier as a toner image. The image forming apparatus according to claim 1, wherein the image forming unit includes a cleaning device that cleans a surface of the image carrier after transferring the toner image. 5. The image forming apparatus according to claim 1, wherein the image forming unit is a process cartridge having an image carrier and at least one image forming device for forming a toner image on the image carrier. apparatus.

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