JP2018155926A - Image formation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress blade turn up by controlling toner supply to a blade contact part under a condition that even a reverse polarity bias is applied.SOLUTION: The image formation apparatus includes: an image holding body; a transfer member which transfers an image on the image holding body to the surface of itself or the surface of a recording material conveyed by itself with application of voltage to a gap between the image holding body and itself; a removal member which removes an unnecessary object from the surface of the transfer member with rubbing with the surface of the transfer member; a drive machine which drives the transfer member so that at least the peripheral surface of the transfer member circularly moves; a detector which detects a load of a drive in the drive machine; and a reverse polarity controller which temporarily switches the voltage applied to the gap between the image holding body and the transfer member to the voltage in the reverse polarity with respect to the voltage at the time when the image is transferred, and uses the second voltage smaller than the first voltage in the first case as the voltage in the reverse polarity in the second case where the load detected by the detector is larger than the load in the first case.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an image forming apparatus.

  2. Description of the Related Art Conventionally, as an image forming apparatus, an image forming apparatus in which a transfer member for transferring an image by applying a voltage to an image holding member is known, and has a means for cleaning the transfer member. Is also known.

  For example, Patent Document 1 has a sensor for detecting the surface potential of the toner layer on the intermediate transfer member, a sensor for detecting the toner adhesion amount on the image carrier, and a control unit for controlling the bias applied to the cleaning unit. A technique for controlling the applied bias in accordance with the toner layer surface potential and the amount of toner adhesion is disclosed.

  Further, for example, in Patent Document 2, a developing bias voltage is applied between the image carrier and the developing means, a controlling means for controlling the developing bias voltage, a developing current detecting means for detecting the current value of the developing means, And a technique for controlling the cleaning bias voltage in accordance with the value of the detected developing current.

JP 2006-259103 A JP 2006-259305 A

  When the transfer member is provided with a removal member that comes into contact with the transfer member and cleans the transfer residual toner from its surface, the removal member other than the cleaning member is applied between the image carrier and the transfer member. It is conceivable to reversely transfer the residual toner on the transfer member to the image carrier by temporarily changing the bias voltage to be applied to the reverse polarity bias. Since the remaining toner is transferred back to the image carrier, the amount of toner supplied to the blade contact portion is reduced, so that the frictional force between the cleaning member and the transfer member is reduced with the aging of the cleaning member and the transfer member. If the size is increased, the blade member may turn over, so-called blade turning.

  An object of the present invention is to suppress blade turning by controlling toner supply to a blade contact portion even under a condition where a reverse polarity bias is applied.

An image forming apparatus according to claim 1 is provided.
An image carrier that holds an image formed on the surface;
A transfer member on which an image on the image carrier is transferred to the surface of the image carrier or the surface of the recording material carried by the device by applying a voltage between the image carrier and the image carrier;
A removal member that rubs against the surface of the transfer member to remove unnecessary materials such as transfer residual toner and paper dust from the surface;
A drive unit that drives the transfer member so that at least the peripheral surface of the transfer member circulates;
A detector for detecting a driving load in the driving machine;
The voltage applied between the image carrier and the transfer member is temporarily switched to a voltage having a polarity opposite to the voltage when the image is transferred, and the load detected by the detector is a first voltage. A reverse polarity controller that uses a second voltage lower than the first voltage in the first case as the reverse polarity voltage in the second case that is larger than the load in the first case;
It is provided with.

The image forming apparatus according to claim 2 is the image forming apparatus according to claim 1,
The transfer member is movable within a moving range including a contact position in contact with the image carrier and a separated position separated from the image carrier;
When the transfer member is in the contact position and the transfer member is in the separated position, the reverse pole controller distinguishes between the first case and the second case as the load threshold. A different threshold value is used depending on the case.

The image forming apparatus according to claim 3 is the image forming apparatus according to claim 1 or 2,
In response to the use of the second voltage as the reverse polarity voltage, the reverse polarity controller includes a warning indicator that displays a warning prompting replacement of the removal member.

The image forming apparatus according to claim 4 is the image forming apparatus according to claim 1 or 2,
In response to the use of the second voltage as the reverse polarity voltage, the reverse polarity controller includes a voltage notification display for displaying a voltage notification indicating that the second voltage has been used. And

The image forming apparatus according to claim 5 is the image forming apparatus according to claim 1 or 2,
In response to the use of the second voltage as the reverse polarity voltage, the reverse polarity controller includes a load notification display for displaying a load notification indicating that the second case has occurred. And

  According to the image forming apparatus of the first aspect, the blade turning can be suppressed as compared with the case where the reverse bias is not controlled and the reverse bias of only a constant output is applied.

  According to the image forming apparatus of the second aspect, even if the transfer member is in contact with or separated from the image carrier, the blade turning can be suppressed. .

  According to the image forming apparatus of the third aspect, replacement of the deteriorated member is prompted.

  According to the image forming apparatus of the fourth aspect, replacement of the deteriorated member is prompted.

  According to the image forming apparatus of the fifth aspect, replacement of the deteriorated member is prompted.

1 is a schematic configuration diagram showing an embodiment of an image forming apparatus of the present invention. It is a figure which shows the detail in the transfer roll periphery of a transfer apparatus. It is a figure which shows the 1st example of a warning. It is a figure which shows the 2nd example of a warning. It is a figure which shows the 3rd example of a warning. It is a table | surface which shows the operation result in an Example and a comparative example.

  Embodiments of the present invention will be described below.

  FIG. 1 is a schematic configuration diagram showing an image forming apparatus according to an embodiment of the present invention.

  The image forming apparatus 1 is a so-called direct transfer type monochrome printer.

  The image forming apparatus 1 includes a photosensitive drum 10. The photosensitive drum 10 is rotatably supported by the drum support frame 10A and is driven by the photosensitive motor 16 to rotate in the direction of arrow A. Around the photosensitive drum 10, a charger 11, an exposure device 12, and a developing device 13 are provided. A toner image is formed on the surface of the photosensitive drum 10 through processes of charging by the charger 11, exposure by the exposure device 12, and development by the developing device 13, and the toner image is formed on the photosensitive drum 10. Retained. Here, the exposure device 12 exposes the photosensitive drum 10 in accordance with image data sent from the outside of the image forming apparatus 1, and an image represented by the image data is formed on the photosensitive drum 10 as a toner image. In order to ensure such exposure accuracy, the photosensitive drum 10 is driven by the photosensitive motor 16 at a stable rotational speed. The photosensitive drum 10 corresponds to an example of an image carrier according to the present invention.

  On the other hand, a sheet P (so-called cut sheet), which is a kind of recording material, is conveyed in the direction of arrow X by a sheet conveyer (not shown), and a transfer region T sandwiched between the photosensitive drum 10 and a transfer device 20 described later is formed. pass. The toner image on the photosensitive drum 10 is transferred onto the paper P while passing through the transfer region T. The remaining toner on the photosensitive drum 10 after the toner image is transferred in the transfer region T is removed from the photosensitive drum 10 by the cleaner 14.

  The paper P that has received the transfer of the toner image in the transfer region T is further conveyed in the direction of the arrow Y and sent to the fixing device 30. The fixing device 30 includes a heating roll 31 that rotates in the direction of arrow D, and a pressure roll 32 that rotates in the direction of arrow E. The heating roll 31 and the pressure roll 32 are in contact with each other to form a fixing region S. The paper P that has traveled in the direction of the arrow Y enters the fixing area S, and while passing through the fixing area S, the toner image on the paper P is fixed on the paper P by being heated and pressurized. As a result of this fixing, an image composed of a fixed toner image is formed on the paper P. The paper P on which the image is formed is sent out of the image forming apparatus 1 by a paper feeder (not shown).

  The transfer device 20 includes a transfer roll 21, a pressure contact roll 22, a peeling roll 23, and an endless transfer belt 24 that is wound around these rolls. The transfer roll 21, the pressure contact roll 22, and the peeling roll 23 are rotatably supported by the transfer device support frame 20A.

  The transfer roll 21 is driven by the transfer motor 26 to rotate in the direction of arrow B, and drives the transfer belt 24. The transfer belt 24 is a resin belt with low stretchability, and circulates and moves in the direction of arrow C in response to the driving force from the transfer roll 21. The transfer belt 24 corresponds to an example of a transfer member according to the present invention, and the transfer motor 26 corresponds to an example of a driving machine according to the present invention. In the present embodiment, the image is transferred not to the surface of the transfer belt 24 itself, which is an example of a transfer member, but to the surface of the paper P conveyed by the transfer belt 24.

  The transfer roll 21 is positioned on the upstream side in the sheet running direction from the rotation center axis of the photosensitive drum 10, and presses the transfer belt 24 against the photosensitive drum 10 from the inside of the transfer belt 24. The transfer roll 21 defines an upstream edge of the transfer region T where the photosensitive drum 10 and the transfer belt 24 are in contact with each other.

  Further, the pressure roller 22 is located downstream of the rotation center axis of the photosensitive drum 10 in the paper traveling direction, and pushes the transfer belt 24 from the inner side of the transfer belt 24 toward the photosensitive drum 10. The press roller 22 defines the downstream edge of the transfer region T.

  The peeling roll 23 is a roll having a smaller diameter than the transfer roll 21, and the paper placed on the transfer belt 24 is abruptly bent by the peeling roll 23 in the traveling direction of the transfer belt 24. The tip of P is peeled off from the transfer belt 24. The sheet P peeled from the transfer belt 24 is guided by the guide member 41 and proceeds in the direction of the arrow Y, and is sent to the fixing device 30 as described above.

  The transfer device 20 also includes a cleaner 25 having a rubber blade that rubs against the surface of the transfer belt 24. Unnecessary substances such as toner and paper dust attached to the transfer belt 24 are removed from the transfer belt 24 by the rubber blade of the cleaner 25.

  FIG. 2 is a diagram showing details in the vicinity of the transfer roll 21 of the transfer device 20.

  The transfer roll 21 is connected to a power source 213. The power source 213 includes a transfer bias unit 214 that generates a transfer bias, a reverse bias unit 215 that generates a reverse polarity bias opposite to the transfer bias, and the transfer bias. A changeover switch 216 that switches between the unit 214 and the reverse bias unit 215 is provided.

  When a transfer bias is applied from the power source 213 to the transfer roll 21, the transfer bias is also applied to the transfer belt 24, and while the sheet P passes through the transfer region T due to the action of the transfer bias, the photosensitive drum 10. The upper toner image is transferred onto the paper P. The power source 213 temporarily switches from the transfer bias unit 214 to the reverse polarity bias unit 215 at a timing such as between image formations, and the reverse polarity bias from the power source 213 is temporarily applied to the transfer roll 21 and the transfer belt 24. Applied. When the reverse bias is applied in this way, the unwanted matter on the transfer belt 24 moves onto the photosensitive drum 10 by the action of the reverse bias. Unnecessary materials that have moved onto the photosensitive drum 10 are removed from the photosensitive drum 10 by the cleaner 14 shown in FIG. The temporary application of the reverse bias contributes to the maintenance of the cleaning property in the cleaner 25 of the transfer device 20.

  The transfer roll 21 has a rotation shaft 211, and the rotation shaft 211 is rotatably supported by a shaft support frame 212. The shaft support frame 212 is supported by a transfer device support frame 20A (see FIG. 1) that supports the entire transfer device 20 so as to be movable up and down.

  A push spring 27 is provided between the shaft support frame 212 and the drum support frame 10A (see FIG. 1) to urge the shaft support frame 212 in a direction away from the drum support frame 10A. The transfer device 20 is also provided with a solenoid 28 that is fixed to the transfer device support frame 20 </ b> A and presses the shaft support frame 212 against the urging force of the pressing spring 27 toward the photosensitive drum 10. FIG. 2 shows a state in which the transfer roller 21 presses the transfer belt 24 against the photosensitive drum 10 by pressing the shaft support frame 212 by the solenoid 28.

  The transfer device 20 includes a control unit 29 including a CPU as a calculation unit and a RAM and ROM as a storage unit 29 </ b> A, and the control of the control unit 29 switches the solenoid 28 on and off. When the solenoid 28 is turned off, the shaft support frame 212 is pushed away from the drum support frame 10 </ b> A by the push spring 27, and as a result, the transfer roll 21 and the transfer belt 24 are separated from the photosensitive drum 10.

  The control unit 29 also controls driving of the transfer roll 21 by the transfer motor 26, and the control unit 29 also detects the load of the transfer motor 26 by monitoring the drive current supplied to the transfer motor 26, for example. . The control unit 29 stores the detected load in the storage unit 29A. That is, the control unit 29 functions as an example of the detector according to the present invention. In the present embodiment, the drive load is detected by the drive current, but the detector referred to in the present invention may detect the drive load by another known detection method.

  The control unit 29 also controls the power source 213 to perform transfer control between the transfer bias and the reverse polarity bias in the changeover switch 216 and voltage control of the transfer bias and the reverse polarity bias in the transfer bias unit 214 and the reverse polarity bias unit 215. ing. Among these, in the reverse bias bias voltage control, the control unit 29 performs control based on the detected load of the transfer motor 26.

  As the load of the transfer motor 26, the frictional resistance between the rubber blade of the cleaner 25 and the transfer belt 24 contributes. The load of the transfer motor 26 is detected by the control unit 29. Detected. If there is too little unnecessary material on the transfer belt 24, this frictional resistance will increase excessively, causing so-called blade turning.

  Therefore, in the present embodiment, for example, a threshold for determining an increase in the frictional resistance between the rubber blade and the transfer belt 24 is stored in the storage unit 29a of the control unit 29, and the detected load of the transfer motor 26 is detected. Is compared with the threshold value to determine whether or not the frictional resistance has increased. The threshold value for such determination is a value representing the load of the transfer motor 26 corresponding to a frictional resistance that is lower than the frictional resistance at which the blade is turned over by the rubber blade and higher than the frictional resistance when an appropriate amount of unnecessary material is present. It has become.

  When the frictional resistance increases, the reverse bias voltage is reduced by the control unit 29, thereby suppressing the movement of unnecessary objects from the transfer belt 24 onto the photosensitive drum 10. As a result, the amount of unwanted matter reaching the rubber blade of the cleaner 25 increases, the frictional resistance between the rubber blade and the transfer belt 24 decreases, and the occurrence of blade turning is suppressed. That is, the control unit 29 functions as an example of the reverse polarity controller according to the present invention.

  The transfer roll 21 and the transfer belt 24 are separated from the photosensitive drum 10 by the operation of the solenoid 28, for example, at an image forming interval. Even in such a case, since the driving of the transfer roll 21 and the transfer belt 24 is continued, the frictional resistance between the rubber blade and the transfer belt 24 may increase during the separation. Therefore, in this embodiment, the load of the transfer motor 26 is detected even during the separation, and it is determined whether or not the frictional resistance between the rubber blade and the transfer belt 24 has increased. However, since the contribution of the photosensitive drum 10 to the load of the transfer motor 26 differs between when the transfer roll 21 and the transfer belt 24 are separated from the photosensitive drum 10, the memory of the control unit 29 is stored. In the part 29a, threshold values for determining an increase in frictional resistance are prepared for each of contact and separation.

  The increase in the frictional resistance between the rubber blade and the transfer belt 24 occurs when not only the unwanted matter on the transfer belt 24 is reduced but also the deterioration and wear of the rubber blade and the transfer belt 24 with time. Therefore, in the present embodiment, not only the turning of the blade is suppressed by reducing the reverse bias, but also the replacement of a part that has deteriorated with time or worn is prompted by a warning described below.

  FIG. 3 is a diagram illustrating a first example of a warning.

  The image forming apparatus 1 according to the present exemplary embodiment includes a UI screen 101 that receives a user operation using, for example, a touch panel and displays information to the user using, for example, a liquid surface display. When the reverse bias voltage is reduced as described above, a warning text 102 is displayed on the UI screen 101 in accordance with an instruction from the control unit 29. The warning sentence 102 illustrated here directly prompts replacement of parts, and parts replacement by a user or a service person who sees the warning sentence 102 is prompted. The UI screen 101 shown in FIG. 3 corresponds to an example of a warning display according to the present invention.

  FIG. 4 is a diagram illustrating a second example of the warning.

  In the example illustrated in FIG. 4, a warning sentence 103 indicating a decrease in the reverse polarity bias is displayed on the UI screen 101. Such a warning sentence 103 reminds a serviceman or the like that there is a possibility that a part of the transfer device 20 is deteriorated or worn over time, and prompts inspection or replacement of parts. The UI screen 101 shown in FIG. 4 corresponds to an example of a voltage notification display according to the present invention.

  FIG. 5 is a diagram illustrating a third example of the warning.

  In the example illustrated in FIG. 5, a warning text 104 indicating that the driving load on the transfer motor 26 is high is displayed on the UI screen 101. Such a warning sentence 104 reminds a service man or the like that the friction between the rubber blade and the transfer belt 24 may be strong, and prompts inspection or replacement of parts. A UI screen 101 shown in FIG. 5 corresponds to an example of a load notification display according to the present invention.

  In addition, although these FIGS. 3-5 show the example which displays a warning etc. by a sentence as a warning indicator, a voltage notification indicator, and a load notification indicator said to this invention, it says to this invention. The warning indicator, the voltage notification indicator, and the load notification indicator may be displayed by lighting a warning lamp or the like.

  Next, examples and comparative examples will be described.

  FIG. 6 is a list showing operation results in the example and the comparative example.

  In the example, as threshold values for discriminating an increase in frictional resistance, threshold values of 1.2 μA during separation and 0.5 μA during contact were used. Further, a reverse bias of -1.2 kV was used during normal friction resistance, and a reverse bias of -0.6 kV was used when frictional resistance was increased.

  On the other hand, in the comparative example, an increase in frictional resistance was not discriminated during contact and separation, and a reverse bias of -1.2 kV was always used.

  During the operation of the example, the drive current value in the transfer motor changed from 0.5 μA to 1.5 μA at the time of separation and changed from 0.2 μA to 0.6 μA at the time of contact. When the drive current value is 0.5 μA at the time of separation and when the drive current value is 1.0 μA at the time of separation, a reverse bias of −1.2 kV is used. Was 1.5 μA, the reverse bias was switched to −0.6 kV. In addition, when the drive current value is 0.2 μA at the time of contact and when the drive current value is 0.4 μA at the time of contact, a reverse bias of −1.2 kV is used, and the drive current value is determined at the time of contact. Was 0.6 μA, the reverse bias was switched to −0.6 kV. As a result of such an operation, the blades were not always turned over in the examples, and the cleaning property was good.

  On the other hand, during the operation of the comparative example, the drive current value in the transfer motor changed from 0.5 μA to 1.5 μA at the time of separation, and changed from 0.2 μA to 0.6 μA at the time of contact. A negative bias of -1.2 kV was used both when the current was 1.5 μA and when the drive current value was 0.6 μA at the time of contact. As a result, the cleaning property was good, but the blade turned up.

  As described above, it was confirmed that switching of the reverse pole bias kept the cleaning property and avoided the blade turning.

  In the above description, cut paper is exemplified as the recording material in the present invention, but the recording material in the present invention may be continuous paper.

  In the above description, a monochrome printer is exemplified as an embodiment of the image forming apparatus of the present invention. However, the image forming apparatus of the present invention may be a color printer, a copying machine, a facsimile machine, or a multifunction machine. There may be.

  In the above description, a direct transfer type apparatus is illustrated as an embodiment of the image forming apparatus of the present invention, and a transfer belt is illustrated as a transfer member according to the present invention. Further, an indirect transfer type apparatus in which an image is transferred from the photosensitive member to the recording material via the intermediate transfer member. In such an indirect transfer type apparatus, the transfer member referred to in the present invention is an intermediate transfer type. It may be a transfer body.

  DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 10 ... Photoconductor drum, 11 ... Charger, 12 ... Exposure device, 13 ... Developing device, 16 ... Photoconductor motor, 20 ... Transfer device, 30 ... Fixing device 21 ...... Transfer roll, 22 ... Pressure roll, 23 ... Peeling roll, 24 ... Transfer belt, 25 ... Cleaner, 26 ... Transfer motor, 27 ... Push spring, 28 ... Solenoid, 29 ... Control unit, 29A …… Storage unit, 213 …… Power supply, 101 …… UI screen, 102,103,104 …… Warning text

Claims (5)

An image carrier that holds an image formed on the surface;
A transfer member that transfers an image on the image carrier onto the surface of the image carrier or the surface of the recording material carried by the device by applying a voltage between the image carrier and the image carrier;
A removal member that rubs against the surface of the transfer member to remove unwanted matter from the surface;
A drive unit that drives the transfer member so that at least the peripheral surface of the transfer member circulates;
A detector for detecting a driving load in the driving machine;
The voltage applied between the image carrier and the transfer member is temporarily switched to a voltage having a polarity opposite to the voltage when the image is transferred, and the load detected by the detector is a first voltage. A reverse polarity controller using a second voltage smaller than the first voltage in the first case as the reverse polarity voltage in the second case larger than the load in the first case;
An image forming apparatus comprising: The transfer member is movable within a moving range including a contact position in contact with the image carrier and a separated position separated from the image carrier;
When the transfer member is in the contact position and the transfer member is in the separation position, the reverse pole controller distinguishes between the first case and the second case as the load threshold. The image forming apparatus according to claim 1, wherein different threshold values are used depending on cases.   3. A warning indicator for displaying a warning prompting replacement of the removal member in response to the use of the second voltage as the reverse polarity voltage by the reverse polarity controller. The image forming apparatus described in 1.   In response to the use of the second voltage as the reverse polarity voltage, the reverse polarity controller includes a voltage notification display for displaying a voltage notification indicating that the second voltage has been used. The image forming apparatus according to claim 1 or 2.   In response to the use of the second voltage as the reverse polarity voltage, the reverse polarity controller includes a load notification display for displaying a load notification indicating that the second case has occurred. The image forming apparatus according to claim 1 or 2.

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