JP2016099485A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent, when an abnormal lateral movement occurs in an intermediate transfer belt in an image forming apparatus, damage to the belt due to the lateral movement and suppress consumption of carrier at the subsequent start-up.SOLUTION: An image forming apparatus primarily transfers toner images formed on respective photoreceptors 11 onto an intermediate transfer belt 31 that is driven to rotate in one direction to compose the images. The image forming apparatus includes: belt abnormality detection means 37 for detecting a movement in the axial direction of the intermediate transfer belt 31; a normal stop sequence after printing processing is completed in a normal state; an abnormal stop sequence of stopping the rotation of the intermediate transfer belt 31 by removing only a charging history on the upstream side of a developing part with respect to the photoreceptors 11; and control means. When detecting an abnormal movement in the axial direction of the intermediate transfer belt 31 on the basis of information from the belt abnormality detection means 37, the control means performs the abnormal stop sequence to stop the rotation of the intermediate transfer belt 31.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an image forming apparatus, and more particularly, to an image forming apparatus for primarily transferring and synthesizing toner images formed on respective photoreceptors onto an intermediate transfer belt that is rotationally driven in one direction.

  In an image forming apparatus such as a tandem type copier or printer in which a plurality of photoconductors are juxtaposed, a toner image formed on each photoconductor is primarily transferred, and further is an intermediate for secondary transfer to a recording material. A transfer belt is provided. When the intermediate transfer belt is driven to rotate, the intermediate transfer belt tends to be offset or meander to one end side in the rotation axis direction.

  For this reason, in large machines, steering control is performed to detect the position of the side of the belt and adjust the shaft of a tension roller or the like. However, this type of steering control increases the cost due to the complexity and size of the belt support mechanism. In small machines, a system is mainly used in which guide ribs are provided on both sides of the belt to restrict the meandering of the belt. Further, there is also used a system in which a belt side regulating member is provided on one of the stretching rollers to regulate the belt from causing a certain amount of lateral movement. However, the method of directly regulating the side portion of the belt cannot cope with the sudden lateral movement of the belt, and has problems such as damage to the belt.

  Patent Documents 1 and 2 describe that when abnormal lateral movement of the intermediate transfer belt is detected, damage to the side portions of the belt is prevented by immediately stopping the rotation of the belt. However, in such stop control, the belt stops with the charge remaining on the photosensitive member, so when the apparatus is started up after correcting the lateral movement of the belt, the charge is developed to the charge remaining on the photosensitive member. The carrier in the agent will adhere. When such carrier consumption occurs and the carrier is transferred to the intermediate transfer belt, there is a problem that the surface of the belt is damaged at the cleaning blade portion or the edge of the cleaning blade is broken.

JP-A-9-16051 JP 2006-343629 A

  The object of the present invention is to prevent the belt from being damaged due to the lateral movement in the event of an abnormal (exceeding a threshold value) lateral movement of the intermediate transfer belt, and to suppress the consumption of the carrier at the next start-up. An object of the present invention is to provide an image forming apparatus capable of performing the above.

An image forming apparatus according to an aspect of the present invention is
In an image forming apparatus for primarily transferring and synthesizing a toner image formed on each photoconductor onto an intermediate transfer belt that is rotationally driven in one direction.
Belt abnormality detecting means for detecting axial movement of the intermediate transfer belt;
A normal stop sequence after the printing process is completed in a normal state;
An abnormal stop sequence for removing only the charging history upstream of the developing unit with respect to the photosensitive member and stopping the rotation of the intermediate transfer belt;
Control means;
With
When the control unit detects an abnormal axial movement of the intermediate transfer belt based on information from the belt abnormality detection unit, the control unit executes the abnormal stop sequence to stop the rotation of the intermediate transfer belt. Letting
It is characterized by.

  In the image forming apparatus, when an abnormal axial movement of the intermediate transfer belt is detected based on information from the belt abnormality detecting unit, only the charging history upstream of the developing unit with respect to the photosensitive member is removed. To stop the rotation of the intermediate transfer belt. Therefore, unnecessary charges do not remain on the photosensitive member, and the carrier in the developer is not consumed when the apparatus is started up after correcting the lateral movement of the belt. The transfer of the carrier is prevented, and as a result, the belt and the cleaning blade are prevented from being damaged. Further, when the intermediate transfer belt undergoes an abnormal lateral movement, the belt only moves a short distance corresponding to the rotation of the photosensitive member from the charging unit to the developing unit, resulting in a heavy burden on the belt. In addition, the belt can be prevented from being damaged.

  According to the present invention, the belt can be prevented from being damaged due to the lateral movement of the intermediate transfer belt, and the consumption of the carrier can be suppressed at the next startup.

1 is a schematic configuration diagram illustrating a color image forming apparatus according to an embodiment. It is a schematic block diagram around a photoconductor. It is a block diagram which shows a control part. FIG. 6 is a flowchart illustrating stop control of an intermediate transfer belt during printing processing. It is a flowchart figure which shows a normal stop sequence. It is a flowchart figure which shows an abnormal stop sequence.

  Embodiments of an image forming apparatus according to the present invention will be described below with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected to the same member and part in each figure, and the overlapping description is abbreviate | omitted.

(Summary of color image forming apparatus, see FIGS. 1 and 2)
First, a schematic configuration of an electrophotographic color image forming apparatus 1 according to an embodiment will be described with reference to FIG. This image forming apparatus 1 is provided with an image reading unit 80 in the upper part, and forms a color image by a tandem method. That is, four image forming units 10 (an image forming unit 10y for forming a yellow image, an image forming unit 10m for forming a magenta image, an image forming unit 10c for forming a cyan image, and a black image are formed. Image forming units 10k) are juxtaposed, and the toner images of the respective colors formed on the respective photoconductors 11 are transferred / synthesized by the electric field applied from the transfer roller 32 onto the intermediate transfer belt 31 (primary transfer). To do. Thereafter, the composite toner image is secondarily transferred onto the recording material by the electric field applied from the transfer roller 35.

  As shown in FIG. 2, a charging roller 12, a developing device 13 including a developing roller 13 a, an all-electric charge eraser lamp 14, and a residual toner cleaning blade 15 are disposed around each photoconductor 11. Furthermore, a laser scanning optical unit 20 is arranged. A process in which a toner image is formed on the photoreceptor 11 by electrophotography using this type of image forming unit 10, is primarily transferred onto the intermediate transfer belt 31, and is further transferred onto the recording material is well known. The detailed explanation is omitted.

  The recording materials are stacked and accommodated in a paper feed cassette 50 and are fed one by one by a paper feed roller 51. The fed recording material is conveyed to the secondary transfer section via the registration roller pair 52, and the toner image is secondarily transferred. Thereafter, the recording material is heated and fixed with toner by the fixing device 60, and is discharged from the discharge roller pair 56 to the discharge portion 57.

  The intermediate transfer belt 31 is stretched endlessly by a driving roller 33 and a holding roller 34 and is driven to rotate in the direction of arrow A. A cleaning blade 36 is in contact with the belt 31 at a portion facing the holding roller 34 with a predetermined pressure, and residual toner on the belt 31 is removed. Further, the belt 31 tends to shift or meander in the direction of the rotation axis as it is driven to rotate. If such a lateral movement exceeds a predetermined threshold, the side portion of the belt 31 is seriously damaged. Therefore, in this embodiment, the belt abnormality detecting means 37 for detecting the lateral movement of the belt 31 is disposed at a position facing both sides of the belt 31. The belt abnormality detection unit 37 may be, for example, a position sensor that detects the amount of movement of the belt 31 in the axial direction, or may be a pressure sensor that detects a pressure value of the belt 31 in the axial direction.

(Control unit, see FIG. 3)
As shown in FIG. 3, the control unit of the image forming apparatus 1 is configured around a CPU 70. As a part related to the present embodiment, detection information from the belt abnormality detection means 37 (position sensor, pressure sensor) is input to the CPU 70. Further, the CPU 70 controls operations of various devices constituting the image forming unit 10 and voltage output values. Further, the CPU 70 detects, as a control program, an abnormal axial movement of the intermediate transfer belt 31 based on a normal stop sequence after the normal printing process is completed and detection information from the belt abnormality detection means 37. And an abnormal stop sequence to be executed at the time.

  The normal stop sequence is a control for removing all the bias application history to the photoconductor 11 and stopping the rotation of the belt 31, which will be described later. The abnormal stop sequence is a control for stopping the rotation of the belt 31 by removing only the charging history upstream of the developing unit with respect to the photoconductor 11, and will be described later.

(Control procedure, see FIGS. 4 to 6)
Here, a control procedure relating to the stop of the intermediate transfer belt 31 in the image forming apparatus will be described.

  Regarding the stop control of the intermediate transfer belt 31 during the printing process, as shown in FIG. 4, when the end of the printing process is confirmed (YES in step S1), a normal stop sequence is executed (step S2). If an abnormal axial movement exceeding the threshold value of the belt 31 is detected based on information from the detection means 37 until the end of the printing process is confirmed (YES in step S3), an abnormal stop sequence is executed (step S3). Step S4). Exceeding the threshold value is detected by the position sensor. If the lateral movement of the belt 31 from the set value exceeds 3.0 mm, for example, if the pressure sensor detects it, the belt 31 is detected. When the pressure on the side of the head exceeds 8.0 N, for example.

  In the normal stop sequence, as shown in FIG. 5, first, the driving of the developing device 13 (rotation of the roller 13a and the like) is stopped, and the primary transfer output from the transfer roller 32 is turned off (step S11). Next, when the final transfer portion (final contact portion with the transfer roller 32) of the photoconductor 11 passes through the charging portion (contact portion with the charging roller 12) (YES in step S12), charging from the charging roller 12 is performed. The output is turned off (step S13). Further, when the final charging portion passes through the developing portion (the portion facing the developing roller 13a) (YES in step S14), the developing bias output is turned off (step S15). Next, when the final charging portion passes through the erase portion (the portion facing the erase lamp 14) (YES in step S16), the driving of the intermediate transfer belt 31 and the photoconductor 11 is stopped (step S17).

  According to the above normal stop sequence, the charge on the photoconductor 11 is completely erased, and there is no possibility that problems such as carrier adhesion to the photoconductor 11 occur when the next printing process is started. In this sequence, after the printing process is completed, the photoconductor 11 is driven one or more times until the final transfer portion passes through the charging portion and the developing portion and passes through the erase portion, and the intermediate transfer belt 13 is also driven to rotate during this period. Will be. However, when abnormal lateral movement of the intermediate transfer belt 31 is detected, it is necessary to urgently stop the driving of the belt 31 in order to avoid damage to the belt 31, and there is room for executing such a normal stop sequence. Absent. On the other hand, it is conceivable to stop the driving of the belt 31 immediately when an abnormal lateral movement of the intermediate transfer belt 31 is detected. However, in this case, when the apparatus is started up after correcting the lateral movement, the photosensitive member is stopped. 11, the carrier in the developer adheres to the already charged portion.

  Therefore, in this embodiment, the photosensitive member 11 (belt 31) is continuously driven for a short period of time to remove only the charging history upstream from the developing portion so that carrier consumption does not occur. That is, in the abnormal stop sequence, as shown in FIG. 6, first, the driving of the developing device 13 (rotation of the roller 13a and the like) is stopped and the charging output from the charging roller 12 is turned off (step S21). Next, when the final charging portion (final contact portion with the charging roller 12) of the photoconductor 11 passes the developing portion (the portion facing the developing roller 13a) (YES in step S22), the developing bias output is turned off. The primary transfer output from the transfer roller 32 is turned off, and the driving of the intermediate transfer belt 31 and the photoconductor 11 is stopped (step S23).

  According to the above abnormal stop sequence, when a lateral movement exceeding the threshold value of the intermediate transfer belt 31 is detected, the belt 31 is driven to rotate for a period of about ３ rotation from the charging unit to the developing unit. . With such a short rotation, there is no possibility that the belt 31 moving laterally will be damaged. Further, since the charged charge on the photoconductor 11 is completely erased, the carrier does not adhere to the photoconductor 11 when the apparatus is started up by correcting the lateral movement of the belt.

(Other examples)
The image forming apparatus according to the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the gist thereof.

  In particular, the image forming apparatus may be a multifunction machine having a communication function, a facsimile function, and the like in addition to a printer having only a print function. The detailed configuration of the image forming unit is arbitrary. The means for detecting the lateral movement of the intermediate transfer belt may be a sensor other than a position sensor or a pressure sensor.

  As described above, the present invention is useful for an image forming apparatus, and in particular, prevents damage to the belt due to abnormal lateral movement of the intermediate transfer belt, and suppresses carrier consumption at the next startup. It is excellent in that it can be done.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus 10 ... Image forming unit 11 ... Photoconductor 12 ... Charging roller 13 ... Developing device 14 ... Eraser lamp 31 ... Intermediate transfer belt 32 ... Primary transfer roller 37 ... Belt abnormality detection means 70 ... CPU

Claims (4)

In an image forming apparatus for primarily transferring and synthesizing a toner image formed on each photoconductor onto an intermediate transfer belt that is rotationally driven in one direction.
Belt abnormality detecting means for detecting axial movement of the intermediate transfer belt;
A normal stop sequence after the printing process is completed in a normal state;
An abnormal stop sequence for removing only the charging history upstream of the developing unit with respect to the photosensitive member and stopping the rotation of the intermediate transfer belt;
Control means;
With
When the control unit detects an abnormal axial movement of the intermediate transfer belt based on information from the belt abnormality detection unit, the control unit executes the abnormal stop sequence to stop the rotation of the intermediate transfer belt. Letting
An image forming apparatus.   The image forming apparatus according to claim 1, wherein the belt abnormality detecting unit detects an axial movement of the intermediate transfer belt.   The image forming apparatus according to claim 1, wherein the belt abnormality detection unit detects an axial pressure of the intermediate transfer belt.   4. The normal stop sequence is a control for removing the entire bias application history to the photosensitive member and stopping the rotation of the intermediate transfer belt. Image forming apparatus.

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