JP2006171522A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a linear encoder which will not impair image, and which will not damage reading accuracy, and to provide a color image forming apparatus of high image quality using the linear encoder, and that is capable of performing the feedback control of a transfer apparatus. <P>SOLUTION: By additionally installing a belt fixing member 103 (with a hole formed in only a reading part) on the side of a scale arranged on the rear side of a belt body 10, the scale position is stabilized, and scale-reading is accurately performed by a scale reading sensor 101. Further, by installing a belt pressure member 102 on the rear side of the scale, pressurizing the scale part from the belt surface side and preventing the waving of the scale, the position of the scale is further stabilized. Further, by arranging a cleaning member 104 on the upstream side of the fixing member 102, soil on the scale surface is scraped into a gap between the members 104 and 103, and then dust is prevented from sticking to the scale and the sensor. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrophotographic image forming apparatus used for a copying machine, a facsimile machine, a printer, and the like, and more particularly to a transfer apparatus having an intermediate transfer unit.

Today, with the demand from the market, many electrophotographic apparatuses, such as color copiers and color printers, output color images.
A color electrophotographic apparatus is provided with a developing device of a plurality of colors around one photoconductor, and a toner is attached by these developing devices to form a composite toner image on the photoconductor, and the toner image is transferred. A so-called one-drum type that records a color image on a sheet, and a plurality of photoconductors provided side by side are each provided with a developing device, and a single-color toner image is formed on each photoconductor. There is a so-called tandem type that sequentially transfers and records a composite color image on a sheet.

Comparing the 1-drum type and the tandem type, the former has only one photoconductor, so that there is an advantage that it can be relatively downsized and cost can be reduced. (4 times) Since image formation is repeated to form a full-color image, it is difficult to speed up image formation. The latter, on the contrary, has the disadvantage of increasing the size and cost, but it is easy to speed up image formation. There is an advantage that is.
Recently, tandem type has been attracting attention because the demand for full-color monochrome speed is desired.

As shown in FIG. 5, the tandem type electrophotographic apparatus includes a direct transfer type that sequentially transfers an image on each photoconductor 40 onto a sheet S conveyed by a sheet conveying belt 12 by a transfer roller 11. As shown in FIG. 1, the images on the photosensitive members 1 are sequentially transferred to the intermediate transfer member 10 by the primary transfer device 62, and then the images on the intermediate transfer member 10 are transferred to the sheet S by the secondary transfer device 22. There are indirect transfer systems that perform batch transfer. The secondary transfer device 22 is a transfer conveyance belt, but there is also a roller-shaped method.
In any of the methods, the function of superimposing and transferring the images of each color without color misregistration is a big problem, and various devices are made to drive at a constant speed.
Further, the tandem type has a problem that color shift is more likely to occur than the one-drum type.

In the case of a one-drum type image forming apparatus, there is only one position on the sheet where the image is transferred, one color image is transferred on one sheet, and one color is transferred on the next. I will go. In this case, the uneven speed component (generated due to belt thickness, curling, etc.) in one cycle of the sheet is not manifested as color misregistration.
However, in the case of the tandem type, since there are a plurality of transfer positions, speed irregularities in one cycle of the sheet also occur as color misregistration. For the tandem type, it is necessary to drive the belt at a constant speed more severely.
One of the countermeasures for the problem is measurement of surface velocity using a linear encoder.
From the output, the belt can be moved at a constant speed by applying feedback to the drive source. Further, it is a means that can be used for correction of the write timing and the like and can be a source of alignment technology.

Japanese Patent Application Laid-Open No. 2004-228561 describes a method of directly detecting the amount of movement of the rotational movement portion of the transfer belt by reading a scale formed on the inner peripheral surface of the transfer belt. However, the present invention stabilizes the scale by fixing the corrugation of the belt and can read the scale with high accuracy. The cleaning member is arranged upstream of the fixed member to prevent dust from adhering to the scale and sensor. The difference is that stable reading is possible over time.
JP 11-24507 A

The present invention provides a linear encoder that does not affect the image and does not impair the reading accuracy, and provides a high-quality color image forming apparatus that can be used for feedback control of the transfer device. Let it be an issue.

As means for solving the above problems, the present invention has the following features.
2. The image forming apparatus according to claim 1, further comprising a belt body and a driving means for driving the belt body, a scale for detecting a moving direction speed of the belt body, and detection for detecting the scale. In the image forming apparatus having means, a position fixing member for pressing the belt body from the back side of the scale detection position is disposed, and a fixing member for pressing the belt body by the sensor detecting the scale from the front side of the scale is disposed. And a cleaning member for cleaning the scale in the upstream direction of the fixing member.
According to a second aspect of the present invention, the image forming apparatus further uses a brush-like member for the position fixing member and the cleaning member.
4. The image forming apparatus according to claim 3, further comprising: a cleaning member and a fixing member which are integrally formed, a hole is formed in a part of the cleaning member, and a direction width perpendicular to a moving direction of the hole. Is made larger than the scale width.

As described above, the image forming apparatus of the present invention uses the means for solving the above problem.
The scale on the belt body is fixed when it is read by the sensor, and angle and distance fluctuations can be reduced, and toner scattering to the sensor and sensor contamination can be prevented.
Further, in the image forming apparatus of the present invention, it is possible to prevent the belt body from being worn. In addition, since the position fixing member and the cleaning member can be configured and manufactured as one body, the function can be achieved with a simple configuration.
Furthermore, in the image forming apparatus of the present invention, the toner scraped off by the cleaning member can be dropped before the sensor is detected, and contamination of the sensor and scale and toner adhesion can be prevented. In addition, by integrating the configuration, the configuration can be simplified and the cost can be reduced.

FIG. 1 shows an image forming apparatus configuration according to claims 1 to 3 of the present invention, and an operation configuration will be described.
In the figure, reference numeral 100 is a copying machine main body, 200 is a paper feed table on which it is placed, 300 is a scanner mounted on the copying machine main body 100, and 400 is an automatic document feeder (ADF) further mounted thereon.
The copying machine main body 100 is provided with an endless belt-shaped intermediate transfer member 10 in the center. The intermediate transfer member 10 corresponds to the belt member in claims 1 to 3. As shown in FIG. 1, in the illustrated example, it is wound around three support rollers 14, 15, and 16 so that it can be rotated and conveyed clockwise in the figure.
In this illustrated example, an intermediate transfer body cleaning device 17 that removes residual toner remaining on the intermediate transfer body 10 after image transfer is provided to the left of the second support roller 15 among the three.

Further, four images of black, cyan, magenta, and yellow are formed on the intermediate transfer member 10 stretched between the first support roller 14 and the second support roller 15 among the three along the conveyance direction. The tandem image forming apparatus 20 is configured by arranging the forming units 18 side by side.
An exposure device 21 is further provided on the tandem image forming apparatus 20 as shown in FIG.
On the other hand, a secondary transfer device 22 is provided on the side opposite to the tandem image forming apparatus 20 with the intermediate transfer body 10 interposed therebetween. In the illustrated example, the secondary transfer device 22 is configured by spanning a secondary transfer belt 24, which is an endless belt, between two rollers 23, and is pressed against the third support roller 16 via the intermediate transfer body 10. The image on the intermediate transfer body 10 is transferred to a sheet.
A fixing device 25 for fixing the transfer image on the sheet is provided beside the secondary transfer device 22. The fixing device 25 is configured by pressing a pressure roller 27 against a fixing belt 26 that is an endless belt.
The secondary transfer device 22 described above is also provided with a sheet transport function for transporting the image-transferred sheet to the fixing device 25. Of course, a non-contact charger may be arranged as the secondary transfer device 22, and in such a case, it is difficult to provide this sheet conveyance function together.

In the illustrated example, under such a secondary transfer device 22 and a fixing device 25, a sheet reversing device 28 for reversing the sheet so as to record images on both sides of the sheet in parallel with the tandem image forming device 20 described above. Is provided.
Now, when making a copy using this color copying machine, a document is set on the document table 30 of the automatic document feeder 400. Alternatively, the automatic document feeder 400 is opened, a document is set on the contact glass 32 of the scanner 300, and the automatic document feeder 400 is closed and pressed by it.
When a start switch (not shown) is pressed, when the document is set on the automatic document feeder 400, the document is transported and moved onto the contact glass 32, and then the document is set on the other contact glass 32. At that time, the scanner 300 is immediately driven to travel the first traveling body 33 and the second traveling body 34. Then, the first traveling body 33 emits light from the light source and further reflects the reflected light from the document surface toward the second traveling body 34, and is reflected by the mirror of the second traveling body 34 and passes through the imaging lens 35. The document is placed in the reading sensor 36 and the original content is read.

When a start switch (not shown) is pressed, one of the support rollers 14, 15, and 16 is driven to rotate by a drive motor (not shown), and the other two support rollers are driven to rotate to convey the intermediate transfer member 10. To do. At the same time, the individual image forming means 18 rotates the photosensitive member 40 to form black, yellow, magenta, and cyan single-color images on each photosensitive member 40, respectively. Then, along with the conveyance of the intermediate transfer member 10, the single color images are sequentially transferred to form a composite color image on the intermediate transfer member 10.
On the other hand, when a start switch (not shown) is pressed, one of the paper feed rollers 42 of the paper feed table 200 is selectively rotated, and the sheet is fed out from one of the paper feed cassettes 44 provided in multiple stages in the paper bank 43, and the separation roller 45. Then, the sheets are separated one by one into the paper feed path 46, transported by the transport roller 47, guided to the paper feed path 48 in the copying machine main body 100, and abutted against the registration roller 49 and stopped.
Alternatively, the sheet feed roller 50 is rotated to feed out the sheets on the manual feed tray 51, separated one by one by the separation roller 52, put into the manual feed path 53, and abutted against the registration roller 49 and stopped.

Then, the registration roller 49 is rotated in synchronization with the composite color image on the intermediate transfer body 10, the sheet is fed between the intermediate transfer body 10 and the secondary transfer device 22, and transferred by the secondary transfer device 22. A color image is recorded on the sheet.
The sheet after the image transfer is conveyed by the secondary transfer device 22 and sent to the fixing device 25, and heat and pressure are applied to the fixing device 25 to fix the transferred image. The paper is discharged at 56 and stacked on the paper discharge tray 57. Alternatively, it is switched by the switching claw 55 and put into the sheet reversing device 28, where it is reversed and guided again to the transfer position, and the image is recorded also on the back surface, and then discharged onto the discharge tray 57 by the discharge roller 56.
On the other hand, the intermediate transfer body 10 after the image transfer is removed by the intermediate transfer body cleaning device 17 to remove residual toner remaining on the intermediate transfer body 10 after the image transfer, so that the tandem image forming apparatus 20 can prepare for another image formation.

  Similar to the invention of Patent Document 1, in the present invention, a scale is provided on the belt, and this is read to measure the belt speed. In the present invention, as shown in FIG. 2, a scale is provided at the end of the back surface of the intermediate transfer belt 10, and the belt speed is measured by reading this with an optical sensor. By feeding back the measurement result to the belt drive unit, the belt speed can be driven to be constant, and each color shift on the belt can be prevented.

FIG. 3 shows an example of the invention of claims 1 and 2 of the present invention.
A belt fixing member 103 (having a hole in only the reading portion) is added to the front side of the scale of the belt body 10, whereby the scale position is stabilized, and the scale reading by the scale reading sensor 101 can be performed with high accuracy. Further, a belt pressing member 102 is installed on the back side of the scale, and the scale portion is pressed from the back side. The pressing member 102 presses the scale from the front side to prevent the scale from wavy. Thereby, the position of the scale is further stabilized. In the example of the present invention, the cleaning member 104 is disposed upstream of the fixing member 102. The dirt on the surface of the scale is scraped off by this 104 and dropped in the gap between 104 and 103 to prevent dust from adhering to the scale and sensor.

FIG. 4 shows an example of the invention of claim 3 of the present invention.
A belt fixing member 103 and a cleaning member 104 are added on the front side of the scale of the belt body 10 and a hole larger than the scale is made in front of the sensor so that scratches, foreign matters, etc. are removed. Can be scraped off, and dust can be prevented from adhering to the scale and sensor. The function can be achieved with a simpler configuration than arranging the fixing member and the cleaning member separately.

1 is a schematic configuration diagram of an indirect transfer tandem image forming apparatus showing an embodiment of the present invention. It is an example of a reading structure of the scale on a belt body which shows one Example of this invention. It is the structure schematic which shows one Example of invention in Claim 1, 2 of this case. It is the structure schematic which shows one Example of the invention in this Claim 3. 1 is a schematic configuration diagram of a tandem image forming apparatus of a direct transfer system showing an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Intermediate transfer body 11 Transfer roller 12 Sheet conveyance belt 14,15,16 Support roller 17 Intermediate transfer body cleaning apparatus (cleaning means)
18 Image forming means 20 Tandem image forming apparatus 21 Exposure apparatus 22 Secondary transfer apparatus (secondary transfer section)
23 Roller 24 Secondary transfer belt 25 Fixing device 26 Fixing belt 27 Pressure roller 28 Sheet reversing device 30 Document table 32 Contact glass 33 First traveling member 34 Second traveling member 35 Imaging lens 36 Reading sensor 40 Photosensitive member (image carrier) body)
42 Paper feed roller 43 Paper bank 44 Paper cassette 45 Paper dust separation roller 46 Paper feed path 47 Transport roller 48 Paper feed path 49 Registration roller 50 Paper feed roller 51 Manual tray 52 Separation roller 53 Manual paper feed path 55 Switching claw 56 Ejection Roller 57 Paper discharge tray 70 Paper dust removing brush roller 71 Secondary transfer cleaning blade 72 Flicker member 73 Secondary transfer roller 74 Collection coil 100 Copying device main body 200 Paper feed table,
300 scanner,
400 Automatic Document Feeder (ADF)

Claims (3)

In an image forming apparatus having a belt body and a driving means for driving the belt body, having a scale for detecting the moving direction speed of the belt body, and having a detecting means for detecting the scale,
A position fixing member that presses the belt body from the back side of the detection position of the scale is arranged, and a fixing member that presses the belt body is arranged near the sensor that detects the scale from the front side of the scale, and the fixing member An image forming apparatus having a cleaning member for cleaning a scale in an upstream direction. The image forming apparatus according to claim 1.
The image forming apparatus uses a brush-like member as a position fixing member and a cleaning member. 3. The image forming apparatus according to claim 1, wherein the image forming apparatus includes a cleaning member and a fixing member integrally formed, a hole is formed in a part of the cleaning member, and a direction width perpendicular to a moving direction of the hole is formed. An image forming apparatus characterized in that it is larger than the scale width.

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