JP2008139648A - Method for manufacturing transfer unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method capable of inexpensively manufacturing a transfer unit, which can obtain a satisfactory quality image by preventing color smear in a sub-scanning curve of an image caused by the deflection of rollers extending an intermediate transfer member during the transfer of an image to a transfer material, with a simple configuration by using simple components. <P>SOLUTION: The increment of the diameter at the middle part of at least one of the plurality of rollers extending the intermediate transfer member is determined in accordance with the amount of sub-scanning curve in an image transferred to a recording material. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a transfer unit of an image forming apparatus such as an electrophotographic copying machine, a facsimile machine, or a printer.

  Various methods are known as an image forming apparatus for forming a color image, and one of them is a method called a tandem method. The tandem image forming apparatus includes a photosensitive drum as an image carrier, an optical scanning device that writes image information data on the photosensitive drum, a developing unit that develops an electrostatic latent image formed on the photosensitive drum, and the like. A plurality of image forming apparatuses and a transfer unit for transferring an image, which is a toner image formed on the photosensitive drum in each image forming apparatus, onto one recording material.

  As an image forming apparatus provided with the transfer unit, an image formed on an image carrier is transferred to an intermediate transfer member (hereinafter also referred to as a transfer belt) composed of an endless belt of the transfer unit, and the image on the intermediate transfer member is transferred. What is transferred to a recording material is known. Since the image forming apparatus using the intermediate transfer member can superimpose the image formed on the image carrier on the intermediate transfer member, it is widely applied to a color image forming apparatus for forming a color image on a recording material. ing. In this color image forming apparatus, images of three colors of yellow (Y), magenta (M), cyan (C), or black (Bk) added to each image carrier are used as intermediate transfer members. After superimposing and transferring, the superposed image is collectively transferred to a recording material using electrostatic force.

  In the transfer of the image formed on the image carrier to the intermediate transfer member, each color is transferred at a predetermined timing so that no shift (color shift) occurs in the superposition of the colors.

  However, since the intermediate transfer member is stretched around a plurality of rollers with a predetermined tension, the axial transfer of the rollers is caused.

  An example of the image forming apparatus is shown in FIG. FIG. 2 is a partial view of the transfer unit 60 of FIG. FIG. 3 is a schematic view of the intermediate transfer member 6 and the rollers 61 and 62 as viewed from the direction of the arrow X1 in FIG. 2. As described above, the rollers 61 and 62 that stretch the intermediate transfer member 6 are bent in the axial direction. Indicates the state. FIG. 3 shows a case where the rollers 61 and 62 are parallel rollers having the same diameter over the entire width of the rollers.

  As shown in FIG. 2, when the rollers 61 and 62 are bent in the axial direction, a difference in circumferential length occurs between both end portions and the central portion of the intermediate transfer body 6. For this reason, the length of movement of the image transferred from the image carrier to the intermediate transfer body 6 until the image is transferred to the recording paper P differs between the both ends and the center of the intermediate transfer body 6. When the transferred image is transferred to the recording material P, sub-scanning bending occurs in the sub-scanning direction (recording material conveyance direction).

  FIG. 4A shows an example of a line drawing of each color image transferred to the recording material P in the case of the arrangement of the image carriers 1Y, 1M, 1C, and 1K and the intermediate transfer body 6 shown in FIG. It is the figure which showed the state of the sub scanning curve at the time of being transcribe | transferred to P separately for each color. Here, the recording material P is conveyed in the arrow X direction. The image transferred to the intermediate transfer member 6 by the image carrier 1Y is transferred to the recording paper P as a yellow image YL in FIG. Similarly, a cyan image CL, a magenta image ML, and a black image BkL are transferred. As will be understood from this, the image transferred onto the intermediate transfer body 6 near the rollers 61 and 62 is more easily affected by the deflection of the roller, and more likely to cause sub-scanning bending.

  As described above, since each color is transferred to the recording material P in a state where there is a sub-scanning curve, there is a problem that even if the respective colors are superimposed, a color shift occurs and a high-quality image cannot be obtained. FIG. 4B is a diagram showing a state in which the image end portions of the respective colors are combined and overlapped, and the cyan image CL and the magenta image ML are omitted. In this way, even if the image ends are aligned, color misregistration occurs at the center.

On the other hand, a color misregistration detection unit is disposed in the vicinity of the intermediate transfer member, and the attitude of the imaging element in the sub-scanning direction is controlled by an actuator based on information from the color misregistration detection unit, and the scanning line is bent. It is disclosed that the scanning line position and / or the scanning line inclination is corrected (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 2004-286981

  As described above, the image forming apparatus using the intermediate transfer member can superimpose the image formed on the image carrier on the intermediate transfer member, so that the color image forming apparatus for forming a color image on a recording material is used. Widely applied. However, since the sub-scanning curve of the image occurs, there is a problem that when the respective colors are superimposed, a color shift occurs and a high-quality image cannot be obtained. Japanese Patent Application Laid-Open No. 2005-228561 corrects a sub-scanning curve of an image with a writing beam that detects image misregistration and controls the posture of an imaging element included in the optical scanning device in the sub-scanning direction and writes image information data. .

  For this reason, an attitude control unit, a sub-scanning curve correcting unit, a sub-scanning curve detecting unit, and the like of the image forming element are required, and the apparatus is complicated and expensive.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for manufacturing a transfer unit that can prevent sub-scanning bending with a simple configuration and can obtain a high-quality image without causing color misregistration. .

The above object is achieved by the following method.
1. A method of manufacturing a transfer unit including an endless belt stretched by a plurality of rollers, which transfers images carried by a plurality of image carriers to a recording material,
The amount of increase in the diameter of the central portion of at least one of the plurality of rollers is determined in accordance with the amount of sub-scanning bending of the image transferred onto the recording material. A method for manufacturing a transfer unit.
2. 2. The transfer unit manufacturing method according to 1, wherein the roller is manufactured by cutting.
3. 2. The method for manufacturing a transfer unit according to 1, wherein the roller is manufactured by molding.
4). The amount of increase in the diameter of the central portion of the roller is determined by measuring a sub-scanning bending amount of an image transferred to the recording material by an image forming experiment. Manufacturing method of the transfer unit.
5. 4. The method according to claim 1, wherein an amount of increase in the diameter of the central portion of the roller is determined by measuring a sub-scanning bending amount of an image transferred to the recording material using an image sensor. A method for manufacturing a transfer unit.
6). The amount of increase in the diameter of the central portion of the roller is determined by estimating the amount of sub-scanning bending of the image when transferred to the recording material by calculating the rigidity of the roller or the endless belt. The manufacturing method of the transfer unit of any one of these.
7). The amount of increase in the diameter of the central portion of the roller is determined by measuring the amount of deformation of the roller or the endless belt and estimating the amount of sub-scanning bending of the image when transferred to the recording material. The method for producing a transfer unit according to any one of 1 to 3.
8). The amount of increase in the diameter of the central portion of the roller is determined by measuring the peripheral speed of the endless belt and estimating the amount of sub-scanning bending of the image when transferred to the recording material. The manufacturing method of the transfer unit of any one of these.
9. 9. The method for manufacturing a transfer unit according to any one of 1 to 8, wherein the image carrier is a drum-shaped image carrier.
10. 9. The method for manufacturing a transfer unit according to any one of 1 to 8, wherein the image carrier is a belt-like image carrier.
11. 11. The method for manufacturing a transfer unit according to any one of 1 to 10, wherein the transfer unit includes an intermediate transfer body onto which an image visualized by a developer is transferred.
12 11. The method of manufacturing a transfer unit according to any one of 1 to 10, wherein the transfer unit includes a conveyance belt that conveys a recording material.

  According to the present invention, it is possible to manufacture a transfer unit capable of preventing sub-scanning bending with a simple configuration using simple components and at low cost, and thereby obtaining a high-quality image without causing color misregistration.

  Embodiments of a fixing device according to the present invention will be described below with reference to the drawings. The present invention is not limited to the following.

  FIG. 1 is a diagram showing an example of an image forming apparatus to which the transfer unit manufacturing method of the present invention can be applied.

  The image forming apparatus according to the present invention includes an image forming apparatus main body GH and an image reading apparatus YS. The image forming apparatus main body GH is called a tandem color image forming apparatus, and includes a plurality of sets of image forming units 10Y, 10M, 10C, and 10K, a transfer unit 60 having an endless belt-like intermediate transfer body 6, a paper feed conveyance And a fixing device 9.

  An image reading device YS including an automatic document feeder 201 and a document image scanning exposure device 202 is installed on the upper part of the image forming apparatus main body GH. The document d placed on the document table of the automatic document feeder 201 is transported by a transport unit, and an image on one or both sides of the document is scanned and exposed by the optical system of the document image scanning exposure device 202, and the line image sensor CCD is scanned. Is read.

  A signal formed by photoelectric conversion by the line image sensor CCD is subjected to analog processing, A / D conversion, shading correction, image compression processing, and the like in an image processing unit, and then exposure means 3Y, 3M, 3C, 3K. Sent to.

  In the image forming unit 10Y that forms a yellow (Y) image, a charging unit 2Y, an exposure unit 3Y, a developing device 4Y, and a cleaning unit 8Y are arranged around the photosensitive drum 1Y. In the image forming unit 10M that forms a magenta (M) color image, a charging unit 2M, an exposure unit 3M, a developing device 4M, and a cleaning unit 8M are arranged around the photosensitive drum 1M. In the image forming unit 10C that forms a cyan (C) color image, a charging unit 2C, an exposure unit 3C, a developing device 4C, and a cleaning unit 8C are arranged around the photosensitive drum 1C. In the image forming unit 10K that forms a black (Bk) image, a charging unit 2K, an exposure unit 3K, a developing device 4K, and a cleaning unit 8K are arranged around the photosensitive drum 1K. The charging unit 2Y and the exposure unit 3Y, the charging unit 2M and the exposure unit 3M, the charging unit 2C and the exposure device 3C, and the charging unit 2K and the exposure device 3K constitute a latent image forming unit.

  The developing devices 4Y, 4M, 4C, and 4K include a two-component developer including a toner having a small particle size of yellow (Y), magenta (M), cyan (C), and black (Bk) and a carrier. The toner in the present embodiment contains a wax component such as a fatty acid ester, for example, in an amount of 8 to 12 parts by mass and is manufactured by a polymerization method, but is not limited thereto.

  The intermediate transfer body 6 is wound around a plurality of rollers and is rotatably supported.

  The fixing device 9 is stretched between a first pressure roller 93 having an elastic layer on a metal core, a heating roller 92 having a heating means inside, and between the first pressure roller 93 and the heating roller 92. An endless fixing belt 91 and a second pressure roller 94 which is disposed in a position facing the first pressure roller 93 so as to be in pressure contact with the fixing belt 91 and forms a fixing nip portion. The unfixed toner surface of the recording material P carrying the toner passes through the fixing nip portion in a direction in contact with the fixing belt 91 so that the unfixed toner is fixed to the recording material P by heating and pressing.

  Thus, each color image formed by the image forming units 10Y, 10M, 10C, and 10K is sequentially superimposed and transferred onto the rotating intermediate transfer body 6 by the transfer means 7Y, 7M, 7C, and 7K (primary). Transfer), an image in which a color image is synthesized is formed. The recording material P accommodated in the paper feeding cassette 20 is fed by the paper feeding means 21 and is conveyed to the transfer means 7A via the paper feeding rollers 22A, 22B, 22C, 22D, the registration rollers 23, etc. A color image is transferred onto P (secondary transfer). The recording material P to which the color image has been transferred is heated and pressurized in the fixing device 9 and the color image on the recording material P is fixed. Thereafter, the sheet is sandwiched between the sheet discharge rollers 24 and placed on the sheet discharge tray 25 outside the apparatus.

  On the other hand, after the color image is transferred to the recording material P by the transfer means 7A, the residual toner is removed by the cleaning means 8A from the intermediate transfer body 6 from which the recording material P is separated by curvature.

  Next, a transfer unit using the transfer unit manufacturing method according to the present invention will be described.

  5 is a schematic view of the intermediate transfer member 6 and the rollers 61 and 62 of the transfer unit 60 as viewed from the direction of the arrow X1 in FIG. 2. The roller 61 is a parallel roller, and the roller 62 has an end portion with a diameter Dc at the center. It is comprised with what is called a crown roller increased from the diameter Ds. The crown of the roller 62 is formed in a linear shape or an arc shape. In the present embodiment, the machining of the roller 62 uses a cutting process in order to increase the dimensional accuracy. However, when the number of rollers 62 produced is large and it is advantageous in terms of cost even if a high-precision mold is used, it is preferable to perform processing by molding from the viewpoint of cost.

  The amount of increase (Dc−Ds) that increases the diameter of the central portion of the roller 62 relative to the diameter of the end portion is determined according to the amount of sub-scanning bending of the image transferred to the recording material P.

  The amount of increase in the diameter of the central portion of the roller 62 is determined by measuring the amount of sub-scanning bending of an image formed by superimposing colors in an image forming experiment in which an image is formed on the recording material P. The measurement of the amount of sub-scanning bending is performed by measuring the maximum interval between the images at the center of the image as shown in FIG. The measurement is performed by visual observation of the maximum interval using a measurement tool (scale, magnifier, etc.). In this embodiment, the measurement is performed by measuring the interval h between the yellow image YL and the black image BkL having a large amount of bending.

  The measured interval h is set as a reference value for the amount of increase in the diameter of the central portion of the roller 62, and the optimum value is determined by further fine-tuning the image with the roller 62 set to the reference value.

  In this embodiment, the interval between the sub-scanning bends is h = 100 μm, and the increase in the diameter of the roller central portion is set to 100 μm to prevent color misregistration.

  For the measurement, a length measuring device such as an image sensor may be used. As a result, visual measurement errors can be eliminated, and measurement can be performed more easily and accurately.

  Further, the amount of bending of the rollers 61 and 62 when the intermediate transfer body 6 is stretched is calculated in advance by rigidity calculation, and the amount of increase in the diameter of the central portion of the roller 62 is estimated by estimating the sub-scanning bending amount based on this amount of bending. The reference value may be determined, and further fine-tuning may be performed by an image drawing experiment. Thereby, determination of the increase amount of the diameter of the center part of the roller 62 can be performed rapidly.

  The sub-scanning bending amount may be estimated by measuring the deformation amount of the rollers 61 and 62 or the intermediate transfer member 6 in a state where the intermediate transfer member 6 is stretched around the roller. Alternatively, the peripheral speed of the intermediate transfer member 6 may be measured. Thus, by estimating the sub-scanning bending amount based on the measurement with an actual machine, it is possible to make an estimation closer to the actual system.

  As described above, the length of the movement of the image transferred from the image carrier to the intermediate transfer body 6 until it is transferred to the recording paper P can be adjusted between the both ends and the center of the intermediate transfer body 6. Color misregistration due to the sub-scanning bend can be prevented. As a result, it is possible to manufacture the transfer unit 60 that can obtain a high-quality image without causing color misregistration with a simple configuration and low cost using simple components.

  In the present embodiment, the image carrier (1Y, 1M, 1C, 1K) is a drum-shaped photosensitive drum. However, an endless belt may be used to form a belt. An example is shown in FIG. Since Y, M, C, and Bk have the same configuration, only Y color will be described. The belt-shaped image carrier 1Y1 is stretched between rollers 1Y2 and 1Y3. A charging unit 2Y, an exposure unit 3Y, a developing device 4Y and a cleaning unit 8Y (not shown) are arranged around the image carrier 1Y1 stretched around the roller 1Y3. The configuration conforms to that of the photosensitive drum shown in FIG. FIG. 6 shows an example in which the image carrier 1Y1 is stretched between two rollers, but two or more rollers may be used. Thereby, the freedom degree of arrangement | positioning of the charging means 2Y, the exposure means 3Y, the image development apparatus 4Y, and the cleaning means 8Y can also be increased.

  In this embodiment, the endless belt of the transfer unit 60 is an intermediate transfer member. However, as another embodiment, the endless belt may not be used as an intermediate transfer member but may be used as a recording material conveyance belt. FIG. 7 is a diagram illustrating an example of the transfer unit according to another embodiment. From the right direction of FIG. 7, the recording material is transferred to a transfer portion composed of transfer means (7Y, 7M, 7C, 7K) arranged to face the photosensitive drum (1Y, 1M, 1C, 1K) via the conveyance belt 6b. The image formed on the photosensitive drum is transferred to the recording material P by passing P while being placed and conveyed by the conveying belt. Also in this case, since the recording material P is nipped and conveyed by the photosensitive drums (1Y, 1M, 1C, 1K) and the transfer means (7Y, 7M, 7C, 7K) via the conveyance belt 6b, the same as described above. Further, color deviation occurs due to the bending of the rollers 61b and 62b. Therefore, in accordance with the form of the transfer unit shown in FIG. 1, the color shift due to the sub-scanning curve of the image can be prevented by increasing the diameter of the central portion of the roller 62b from the diameter of the end portion by the method described above.

FIG. 2 is a diagram of an image forming apparatus to which the transfer unit manufacturing method of the present invention is applicable. FIG. 2 is a partial view of a transfer unit shown in FIG. 1. FIG. 3 is a schematic view of the transfer unit shown in FIG. 2 viewed from the direction of arrow X1 in FIG. FIG. 6 is a diagram showing the state of sub-scanning bending transferred to a recording material for each color. FIG. 6 is a diagram showing the sub-scanning bending state transferred to the recording material in an overlapping manner. It is a figure at the time of making an image carrier into a belt form using an endless belt. FIG. 4 is a diagram when an endless belt of a transfer unit is used as a recording material conveyance belt.

Explanation of symbols

GH image forming apparatus main body YS image reading apparatus P recording material YL yellow image CL cyan image ML magenta image BkL black image 10Y, 10M, 10C, 10K image forming unit 60 transfer unit 6 intermediate transfer member 61, 62 roller 9 fixing device

Claims (12)

A method of manufacturing a transfer unit including an endless belt stretched by a plurality of rollers, which transfers images carried by a plurality of image carriers to a recording material,
The amount of increase in the diameter of the central portion of at least one of the plurality of rollers is determined in accordance with the amount of sub-scanning bending of the image transferred onto the recording material. A method for manufacturing a transfer unit. The method for manufacturing a transfer unit according to claim 1, wherein the roller is manufactured by cutting. The method for manufacturing a transfer unit according to claim 1, wherein the roller is manufactured by molding. 4. The amount of increase in the diameter of the central portion of the roller is determined by measuring a sub-scanning bending amount of an image transferred to the recording material by an image forming experiment. A method for producing the transfer unit according to 1. The amount of increase in the diameter of the central portion of the roller is determined by measuring the amount of sub-scanning bending of the image transferred to the recording material using an image sensor. The manufacturing method of the transcription | transfer unit of description. 2. The amount of increase in the diameter of the central portion of the roller is determined by estimating a sub-scanning bending amount of an image when transferred to the recording material by calculating rigidity of the roller or the endless belt. 4. A method for producing a transfer unit according to any one of items 1 to 3. The amount of increase in the diameter of the central portion of the roller is determined by measuring the amount of deformation of the roller or the endless belt and estimating the amount of sub-scanning bending of the image when transferred to the recording material. The method for manufacturing a transfer unit according to claim 1. The amount of increase in the diameter of the central portion of the roller is determined by measuring the peripheral speed of the endless belt and estimating the amount of sub-scanning bending of the image when transferred to the recording material. 4. A method for producing a transfer unit according to any one of items 1 to 3. The method for manufacturing a transfer unit according to claim 1, wherein the image carrier is a drum-shaped image carrier. 9. The transfer unit manufacturing method according to claim 1, wherein the image carrier is a belt-like image carrier. The method of manufacturing a transfer unit according to any one of claims 1 to 10, wherein the transfer unit includes an intermediate transfer body onto which an image visualized by a developer is transferred. The method of manufacturing a transfer unit according to claim 1, wherein the transfer unit includes a conveyance belt that conveys a recording material.

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