JP2003202788A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inexpensively perform control to form an image on a transfer sheet without causing positional deviation even when the peripheral length of a transfer body is changed. <P>SOLUTION: This image forming apparatus has an image forming means for forming the image based on image data, and a rotating transfer body to which the image is transferred by the image forming means and a means for transferring the image transferred to the transfer body to the transfer sheet, and it is provided with a measuring means for measuring the peripheral length of the transfer body, and image forming timing is set according to the peripheral length of the transfer body measured by the measuring means. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine, etc.
The present invention relates to an image forming apparatus that forms an image by using a transfer body whose peripheral length changes depending on a use environment.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus that visualizes an electrostatic latent image formed on a photoconductor with toner, a transfer body (intermediate transfer body) that temporarily rotates the image visualized on the photoconductor. There is known an image forming apparatus which forms an image on a transfer sheet by transferring the image onto the transfer sheet by transferring the image onto the transfer sheet from the intermediate transfer member. In such an image forming apparatus, an image can be formed at a predetermined position on the transfer sheet by controlling the timing of latent image formation on the photoconductor, the rotational speed of the intermediate transfer body, the feeding timing of the transfer sheet, and the like. I am trying.

However, the circumference of the intermediate transfer member changes depending on the environment in which the image forming apparatus is used and deterioration due to long-term use. For example, the intermediate transfer member contracts when the operating environment is at a low temperature, and expands when the operating temperature is at a high temperature. In addition, for example, when a rubber belt is used as the intermediate transfer member, it gradually expands when it is continuously used. Conventionally, since the above-mentioned timing control is performed using a constant control value, when the circumferential length of the intermediate transfer member changes in this way, the position adjustment between the transfer sheet and the image is not normally performed, and the transfer sheet There was a deviation in the image forming position with respect to.

In order to solve such a problem, it is possible to set a correction value according to environmental factors to correct the timing control, but the peripheral length of the intermediate transfer member changes due to various factors. It is difficult to set a correction value according to all the changes, and a sensor etc. for measuring the values of the factors (temperature, usage period, etc.) are also required,
There was a problem that it would lead to higher costs. In addition to this, JP-A-10-123846 and JP-A-10-13
In Japanese Patent No. 3448, the peripheral length of the intermediate transfer member (image carrier) is measured, and the drive means is controlled so that the rotation cycle of the image carrier becomes constant according to the peripheral length, and in accordance therewith. A color image forming apparatus is disclosed that controls the speed of the image forming process.

[0005]

However, these image forming apparatuses have a problem that the control mechanism for controlling the drive mechanism of the intermediate transfer member is required, resulting in an increase in cost. SUMMARY OF THE INVENTION It is an object of the present invention to solve such a problem and to enable an image forming apparatus to perform control of forming an image on a transfer sheet at a low cost without misalignment even when the peripheral length of a transfer body changes. And

[0006]

In order to achieve the above object, there is provided an image forming means for forming an image on the basis of image data, and the image forming means has a rotating transfer member for transferring the image, and In an image forming apparatus having means for transferring an image transferred on a transfer body to a transfer sheet, a measuring means for measuring the peripheral length of the transfer body, and an image according to the peripheral length of the transfer body measured by the measuring means. Image forming timing setting means for setting the forming timing is provided. In such an image forming apparatus, it is preferable to provide a paper feed timing adjusting means for adjusting the paper feed timing of the transfer sheet according to the peripheral length of the transfer body measured by the measuring means. Alternatively, the paper feed timing adjusting means may be provided instead of the image forming timing setting means.

Further, it is preferable to provide a measurement timing setting means for setting the timing at which the measuring means measures the peripheral length of the transfer member, and a means for selecting whether or not the measurement by the measuring means is performed. Further, if a display means for displaying information such as a message and a means for displaying a message to that effect on the display means when the measurement result of the circumferential length of the transfer member by the measuring means does not fall within a predetermined range, Good.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. First, the configuration of a copying machine, which is an embodiment of the image forming apparatus of the present invention, will be described with reference to FIGS. FIG. 5 is a functional block diagram showing the structure of the copying machine, and FIG. 6 is a schematic sectional view showing the structure of the copying machine. This copying machine is a device that forms an image on a sheet 35, which is a transfer sheet, by the image forming unit 15 based on the image data of the document read by the image reading unit 13. Then, as shown in FIG. 5, the main control unit 11, the operation display unit 12, the image reading unit 13, the image storage unit 1
4, image forming unit 15, perimeter sensor 16, perimeter storage unit 17
It is a configuration provided with.

The main controller 11 includes a CPU, a ROM, and a RAM.
It is a unit that controls the entire copying machine. This control is performed by the CPU executing various control programs stored in the ROM, and processes such as peripheral length measurement, image forming timing setting, and sheet feeding timing adjustment described later are also performed by this control program. The operation display unit 12 is a unit including a liquid crystal display or various lamps that are means for displaying information such as messages, and various keys for the user to perform operations such as setting of modes and numerical values. When an input signal from the keys of the operation display unit 12 is transmitted to the main control unit 11, the main control unit 11 operates each unit of the device according to the input and displays the result on the display means.

The image reading unit 13 is a scanner, which scans the surface of the document with a light source (not shown) and receives the reflected light with an optical sensor such as a phototransistor to read the image data of the document. Further, this scanner is a color scanner capable of reading color image data. The image storage unit 14 is a storage unit that stores the image data read by the image reading unit 13, and is configured by a RAM, a hard disk drive (HDD), or the like. The image data read by the image reading unit 13 is temporarily stored in the image storage unit 14 via the main control unit 11, further subjected to various image processing by the main control unit 11, and output to the image forming unit 15. .

The image forming section 15 is an image forming means for forming an image based on the image data, and here the image data is inputted from the main control section 11. This image forming unit 15
As shown in FIG. 6, the developing unit 22, the photosensitive drum 23, the laser writing unit 24, the belt transfer unit 25,
Intermediate transfer belt 26, registration roller 28, paper transfer unit 2
9, a transport unit 30, and a fixing unit 31. In the image forming unit 15, the photoconductor drum 23 rotates counterclockwise as indicated by an arrow, and drives the photoconductor drum 23 charged by a charging unit (not shown) according to image data and timing signals from the main control unit. An electrostatic latent image is formed on the photoconductor drum 23 by scanning the laser beam by the laser writing unit 24.

The electrostatic latent image is visualized by adhering toner by the developing unit 22, and the belt transfer section 25 transfers the visualized image to the intermediate transfer belt 26 which is a transfer body. The intermediate transfer belt 26 rotates clockwise as indicated by an arrow so that the intermediate transfer belt 26 moves in the same direction as the photosensitive drum 23 in the belt transfer section 25. The intermediate transfer belt 26 can be made of rubber such as silicon rubber or urethane rubber or a flexible film such as polyethylene terephthalate (PET). Here, an example made of rubber will be described. Here, the developing unit 22 is a so-called revolver type developing unit including a developing unit 22a corresponding to each color of yellow (Y), magenta (M), cyan (C), and black (K), and is a photosensitive drum. The latent image formed on 23 is visualized by appropriately selecting the color of the toner to be visualized.
Therefore, a full-color image can be formed on the intermediate transfer belt 26 by sequentially forming images of four colors of YMCK in accordance with the image data of each color, aligning the positions, and transferring the images to the intermediate transfer belt 26. .

On the other hand, the registration roller 28 is a registration unit for adjusting the paper feed timing of the paper 35 fed (fed) from the manual feed tray 33 or the paper feed tray 34 to the paper transfer unit 29. This timing adjustment is performed by a control signal from the main control unit 11. The registration roller 28 feeds the paper 35 to the paper transfer unit 29 at the same timing as the image on the intermediate transfer belt 26, transfers the image to the paper 35 by the paper transfer unit 29, and transfers the paper 35 by the transport unit 30. The image is conveyed to the fixing unit 31, heated and pressed to fix the image, and then discharged to the paper discharge tray 32. By such an operation, the image forming unit 15 can form a full-color image on the paper 35 based on the image data input from the main control unit 11.

The perimeter sensor 16 measures the perimeter of the intermediate transfer belt 26 by detecting a line mark provided on the intermediate transfer belt 26 of the image forming section 15 or a belt mark 27 having a predetermined pattern. It is a sensor and a measuring means. The circumference storage unit 17 is a storage unit for storing the circumference of the intermediate transfer belt 26 measured by the circumference sensor 16. These circumference sensors 1
6 and the operation of the circumference storage unit 17 will be described in detail later.
Although the image storage unit 14 and the circumference storage unit 17 are shown as separate components from the main control unit 11 here, the RAM provided in the main control unit 11 may be used as these storage units. .

Next, the image forming timing setting according to the present invention in the above-mentioned copying machine will be described with reference to FIGS. FIG. 1 is a flow chart showing a process of setting an image forming timing in the copying machine, FIG. 2 is a flow chart showing a process when the power is turned on, FIG. 3 is a flow chart showing a process when the process control is operating, and FIG. 6 is a flowchart showing a process of measuring the circumference of the intermediate transfer belt 26 used for timing measurement. In the copying machine described above, the peripheral length of the intermediate transfer belt 26 changes depending on the usage environment of the copying machine, particularly the temperature, and also gradually increases with continued use. Therefore, in this copying machine, the above-described circumference sensor 16 is provided as a measuring means for measuring the circumference of the intermediate transfer belt 26, and the image forming timing is set according to the circumference of the intermediate transfer belt 26 measured by the circumference sensor 16. Image forming timing setting means for setting the writing timing by the laser writing unit 24 is provided. Further, a paper feed timing adjusting means for adjusting the paper feed timing of the paper 35 from the registration rollers 28 according to the circumference of the intermediate transfer belt 26 measured by the circumference sensor 16 is also provided.

This copying machine has a main controller 11 at the time of image formation.
Executes the process shown in the flow of FIG. First step S
1, the circumference is measured by the circumference sensor 16 and the circumference storage unit 17
The peripheral length of the intermediate transfer belt 26 stored in 1 is compared with the peripheral length stored as a reference value. This peripheral length measurement processing will be described later. Then, in step S2, according to the comparison result in step S1, the writing timing of the laser writing unit 24 to the photosensitive drum 23 is changed as the image forming timing. Since the linear velocity for rotating the intermediate transfer belt 26 is constant, the intermediate transfer belt 26
If the circumference of the image is longer than the reference value, it takes a long time to transfer the image of the first color to the intermediate transfer belt 26 and then return the image to the belt transfer unit 25 again. The writing timing is changed so that the writing interval of the image of each color is lengthened by that time. If the circumference of the intermediate transfer belt 26 is shorter than the reference value, the opposite is true. Here, the main controller 11 functions as an image formation timing setting unit.

Next, in step S3, the paper feed timing of the paper 35 from the registration roller 28 is adjusted according to the comparison result in step S1, and the process ends. If the circumference of the intermediate transfer belt 26 is longer than the reference value, the time from the transfer of the image to the intermediate transfer belt 26 to the arrival of the image at the paper transfer portion 29 becomes long. The writing timing is changed so that the interval from the writing of the image to the feeding of the paper 35 by the registration roller 28 is lengthened by the time. If the circumference of the intermediate transfer belt 26 is shorter than the reference value, the opposite is true. Here, the main control unit 11 functions as a paper feed timing adjusting unit.

By such processing, the intermediate transfer belt 2
Since the image forming timing can be set in accordance with the circumference of No. 6, even if the circumference of the intermediate transfer belt 26 changes, the misregistration between the images of the respective colors can be prevented, and an image with less color misregistration is formed. be able to. Further, since the paper feed timing can be adjusted according to the circumference of the intermediate transfer belt 26, an image can be formed at a fixed position on the paper 35 even when the circumference of the intermediate transfer belt 26 changes. Therefore, the quality of the image formed by this copying machine can be improved. Further, since it is only necessary to adjust the operation timing and there is no need to adjust the operation speed of the drive mechanism, it can be realized at low cost.

Even if only one of the image forming timing and the paper feeding timing is adjusted, the effect by that can be obtained. When the paper feed timing is constant, the interval from writing to paper feeding can be lengthened by, for example, advancing the image forming timing, and conversely, the interval can be shortened by delaying.
With this configuration, the position of the image on the sheet can be kept constant only by adjusting the image forming timing. The above process may be performed only when the timing is set such that the circumference of the intermediate transfer belt 26 is used.

The circumference measurement process used in the above process is performed at a timing set by the user or predetermined as a system set value. The timing may be, for example, power-on, process control operation, etc., but the main control unit 11 functioning as a measurement timing setting unit performs the circumference measurement process at an appropriate time according to the user's setting or the system set value. . Of course, the circumference may be measured at another time.
For example, when the circumference setting process is performed when the power is turned on, the process shown in the flowchart of FIG. 2 is performed instead of the normal initial operation when the power is turned on.

First, in step S11, a normal initial operation process is performed. Next, in step S12, it is determined whether or not execution of the circumference measurement operation is set. Here, since the circumference measurement process requires a certain amount of time, it may be troublesome. Therefore, if there is a designation by the user or if the main control unit 11 determines from the information from various sensors that there is no problem, the circumference measurement process may be set not to be performed. Even in this case, the value of the perimeter already stored in the perimeter storage unit 17 can be used for the timing setting, so that the quality of the image is greatly affected if the period does not change significantly. Never give. Especially when the setting that does not perform the circumference measurement processing is not set,
It is assumed that execution of circumference measurement operation is set. If execution of the circumference measurement operation is set in step S12,
In step S13, the circumference measurement operation shown in FIG. 4 is performed. If not set, the process ends.

As shown in FIG. 4, the circumference measuring operation is on standby until the circumference mark 16 is detected by the circumference sensor 16 in step S31. When the belt mark 27 is detected, the process proceeds to step S32, and it is determined whether or not the detection is the first time. If it is the first time, the process proceeds to step S33 to start the timer, and returns to step S31 to wait for the belt mark 27 to be detected again. Step S3
If the detection is not the first time in 2, that is, the second time or later, the process proceeds to step S34, and it is determined whether the measured value of the time by the timer is within a predetermined range. If it is within the predetermined range, the process proceeds to step S35, and the measured value by the timer is stored in the circumference storage unit 17. In this copying machine, since the rotational linear velocity of the intermediate transfer belt 26 is constant, the circumference can be obtained by dividing the detection interval of the belt mark 27 by the circumference sensor 16 by this speed. Therefore, after the circumference sensor 16 detects the belt mark 27 for the first time,
The time until the second detection can be treated as data indicating the circumference of the intermediate transfer belt 26.

After storing the measured value by the timer in step S35, the process proceeds to step S37, and the process returns to the original process even if the number of belt mark detections is initialized to zero. Step S
If the value measured by the timer at 34 is not within the predetermined range, the intermediate transfer belt 26 may be deteriorated. The request message is displayed on the display unit of the operation display unit 12. Then, in step S37, the number of belt mark detections is initialized to 0, and the process returns to the original process. Here, an example is shown in which the circumference is measured only once and the value is adopted, but if the measurement is performed a plurality of times and the average value is adopted, a more reliable value can be obtained.

When the circumference setting process is performed during the process control operation, the process shown in the flowchart of FIG. 2 is performed instead of the normal process control operation during the process control operation. Here, the process control operation means a decrease in the light amount of an exposure unit (not shown) of the image reading unit 13 due to a cause over time, contamination of optical components forming an optical unit (not shown), and output of a charging unit (not shown) of the image forming unit 15. A sensor detects potential fluctuations of the electrostatic latent image due to fluctuations, fluctuations in the sensitivity of the photosensitive drum 23, fluctuations in the residual potential, etc., and feeds back to the charging, exposure, and development processes to control each characteristic value and stabilize This is an operation for obtaining an image.

First, in step S21, a normal process control operation process is performed. Next, in step S22, it is determined whether or not execution of the circumference measurement operation is set. This setting is as described above in the description of step S12 in FIG. If execution of the circumference measurement operation is set, the process proceeds to step S13 and the circumference measurement operation shown in FIG. 4 is performed. If not set, the process ends.

By the above processing, the intermediate transfer belt 26 is turned on at the time of power-on or process control processing.
Since the perimeter is measured and stored in the perimeter storage unit 17, the image forming timing and the paper feed timing can be appropriately set using this value. Further, when the circumference is abnormal, the fact is displayed, so that the user can know the deterioration of the intermediate transfer belt 26 at an appropriate time,
It is possible to replace the intermediate transfer belt 26 and keep the operating condition of the apparatus in good condition. Further, it is possible to prevent the abnormality in other parts of the apparatus by controlling the image forming timing and the sheet feeding timing based on the abnormal circumference. Although an example of a copying machine capable of reading / forming a color image has been described here, the present invention can be similarly applied to a monochrome image forming apparatus. It can also be applied to other image forming apparatuses such as printers and facsimile machines.

[0027]

As described above, according to the image forming apparatus of the present invention, an image can be formed at a fixed position on the transfer sheet even when the peripheral length of the transfer body is changed. The image quality can be improved. Further, since it is only necessary to adjust the operation timing and there is no need to adjust the operation speed of the drive mechanism, it can be realized at low cost.

[Brief description of drawings]

FIG. 1 is a flowchart showing an image forming timing setting process in a copying machine which is an embodiment of an image forming apparatus of the present invention.

FIG. 2 is a flow chart showing a process when the power is turned on.

FIG. 3 is a flow chart showing a process during the process control operation.

FIG. 4 is a flowchart showing a process of measuring the circumference of the intermediate transfer belt 26 which is also used for measuring the image forming timing.

FIG. 5 is a functional block diagram showing the configuration of the copying machine.

FIG. 6 is a schematic cross-sectional view showing the configuration of the copying machine.

[Explanation of symbols]

11: Main control unit 12: Operation display unit 13: Image reading unit 14: Image storage unit 15: Image forming unit 16: Perimeter sensor 17: Perimeter storage 22: Development unit 23: Photosensitive drum 24: Laser writing unit 25: Belt Transfer Section 26: Intermediate Transfer Belt 27: Belt mark 28: Registration roller 29: Paper transfer unit 30: Conveyance unit 31: Fixing unit 32: Paper ejection tray 33: Manual feed tray 34: Paper feed tray 35: paper

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H027 DA50 DE02 DE07 ED06 ED17                       EE07 GA30 GB07                 2H200 FA04 GA10 GA23 GA34 GA44                       GA47 GB22 GB25 HA02 HB12                       HB22 JA02 JC03 JC15 JC20                       MA03 MA20 PA10 PB25

Claims (5)

[Claims] 1. A transfer member having an image forming unit for forming an image based on image data, the rotating transfer member for transferring the image by the image forming unit, and an image transferred on the transfer member on a transfer sheet. In an image forming apparatus having a transfer unit, a measuring unit for measuring the peripheral length of the transfer member, and an image forming timing setting unit for setting an image forming timing according to the peripheral length of the transfer member measured by the measuring unit. An image forming apparatus characterized by being provided. 2. The image forming apparatus according to claim 1, further comprising a paper feed timing adjusting unit that adjusts a paper feed timing of the transfer sheet according to a circumferential length of the transfer body measured by the measuring unit. A characteristic image forming apparatus. 3. An image forming means for forming an image based on image data, wherein a rotating transfer body for transferring the image by the image forming means, and an image transferred on the transfer body on a transfer sheet. In an image forming apparatus having a transfer unit, a measuring unit for measuring a peripheral length of the transfer member, and a sheet feeding timing for adjusting a sheet feeding timing of the transfer sheet according to the peripheral length of the transfer unit measured by the measuring unit. An image forming apparatus comprising an adjusting unit. 4. The image forming apparatus according to claim 1, wherein the measuring unit sets a timing for measuring the peripheral length of the transfer member by the measuring unit, and the measuring unit. And a means for selecting whether or not to perform measurement by the image forming apparatus. 5. The image forming apparatus according to claim 1, further comprising a display unit that displays information such as a message, and the measurement result of the peripheral length of the transfer member by the measuring unit. An image forming apparatus is provided with means for displaying on the display means when the value does not fall within a predetermined range.