JP2013145293A - Image formation apparatus - Google Patents

Abstract

The present invention provides a technique capable of appropriately removing paper dust.
An image forming apparatus detects a quantity of paper dust adhering to a conveyance unit that conveys a recording medium (S130, S160), and a cleaning unit that removes paper dust. A changing unit that changes the cleaning time for removing paper dust by the cleaning unit according to the amount of paper dust detected by the paper dust detecting unit (S170, S180). By changing the cleaning time for removing paper dust according to the detected amount of paper dust, paper dust is appropriately removed.
[Selection] Figure 3

Description

  The present invention relates to an image forming apparatus, and more particularly to a cleaning technique for removing unnecessary toner or the like in the image forming apparatus.

  Conventionally, as a cleaning technique for removing unnecessary toner or the like in an image forming apparatus, for example, a technique described in Patent Document 1 is known. The prior art document discloses a technique for determining the cleaning time of the transfer roller in accordance with the count number of a dot number counter that counts the number of dots during image formation when the exposure means performs image exposure.

JP 2001-142323 A

However, the influence of paper dust other than toner cannot be ignored as an object to be removed, and when removing unnecessary paper dust from the paper, the amount of paper dust attached varies depending on the type of paper. Therefore, even if the number of dots counted by the dot number counter is small, if the amount of paper dust is large, there is a possibility that the paper dust cannot be removed properly by the method as described in the above prior art document.
The present invention provides a technique capable of appropriately removing paper dust.

  An image forming apparatus disclosed in this specification includes a conveyance unit that conveys a recording medium, a paper dust detection unit that detects an amount of paper dust attached to the conveyance unit, and a cleaning unit that removes the paper dust. And a changing unit that changes a cleaning time for removing the paper dust by the cleaning unit in accordance with the amount of paper dust detected by the paper dust detecting unit.

  In the image forming apparatus, the transport unit includes a photoconductor, the cleaning unit removes the paper dust by cleaning the photoconductor, and the change unit has the paper dust amount larger than a predetermined amount. When the number of rotations is large, the cleaning time may be changed by changing the number of rotations of the photoconductor during cleaning to a number of rotations greater than a predetermined number of rotations.

  In the image forming apparatus, the cleaning unit removes the paper dust using a cleaning bias, and the changing unit sets the cleaning bias higher than a reference value when the amount of paper dust is larger than a predetermined amount. The cleaning time may be changed by setting.

  In the image forming apparatus, a photosensitive member is provided as the transport unit, and the cleaning unit removes the developer attached to the photosensitive member, and after the first cleaning is completed, the photosensitive member. And performing the second cleaning for removing the paper dust adhering to the sheet, and the changing unit lowers the cleaning bias below the reference value at least for a period of one rotation of the photosensitive member after the second cleaning is completed. You may make it set.

  In the image forming apparatus, the paper dust detecting unit detects a first paper dust amount before forming an image on the recording medium and a second paper dust amount after forming the image on the recording medium. The changing unit may change the cleaning time based on a difference between the first paper dust amount and the second paper dust amount.

  In the image forming apparatus, the cleaning unit performs a first cleaning to remove the developer attached to the transport unit, and the paper dust detection unit performs the paper dust amount after the first cleaning is completed. May be detected. At that time, the transport unit is provided with a photoconductor, the cleaning unit removes the developer attached to the photoconductor in the first cleaning, and the paper dust detection unit is configured to perform the process after the first cleaning is completed. You may make it detect the said paper dust amount adhering to a photoconductor.

  In the image forming apparatus, the paper dust detection unit includes a photosensor including a light emitting element and a light receiving element, irradiates light from the light emitting element to the transport unit, and the light receiving element emits light from the transport unit. The paper dust amount may be detected based on the amount of received light.

  In the image forming apparatus, the paper dust detection unit includes a voltage generation unit that generates a predetermined detection voltage, applies the detection voltage to the transport unit, and a current value obtained by applying the detection voltage. The amount of paper dust may be estimated based on the above.

  According to the present invention, the changing unit changes the cleaning time for removing the paper dust by the cleaning unit according to the amount of paper dust detected by the paper dust detecting unit. Therefore, paper dust can be removed appropriately.

1 is a schematic cross-sectional view illustrating an internal configuration of a printer according to a first embodiment. 1 is a schematic block diagram of a high-voltage power supply device for a printer. The flowchart which shows the paper dust removal process in Embodiment 1 The flowchart which shows the paper dust removal process in Embodiment 2

<Embodiment 1>
The first embodiment will be described with reference to FIGS.

1. Overall Configuration of Printer FIG. 1 is a schematic sectional view showing an internal configuration of a color printer 1 (an example of an “image forming apparatus”) according to a first embodiment. In the following description, when distinguishing each component for each color, subscripts of Y (yellow), M (magenta), C (cyan), and K (black) are added to the reference numerals of the respective parts, and they are not distinguished. Omits subscripts. The image forming apparatus is not limited to a color printer, and may be, for example, a multifunction machine having a FAX and a copy function, or a monochrome printer.

  A color printer (hereinafter simply referred to as “printer”) 1 includes a paper feed unit 3, an image forming unit 5, a transport mechanism 7, a fixing unit 9, a belt cleaning unit 20, and a high-voltage power supply device 50. For example, the printer 1 generates a toner image composed of toner (developer) of one or a plurality of colors (four colors of yellow, magenta, cyan, and black in this embodiment) corresponding to image data input from the outside. Paper, OHP sheet, etc.).

  The sheet feeding unit 3 is provided at the lowermost part of the printer 1 and includes a tray 17 that accommodates sheets (an example of “recording medium”) 15 and a pickup roller 19. The sheets 15 accommodated in the tray 17 are taken out one by one by a pickup roller 19 and are sent to the transport mechanism 7 via the transport roller 11 and the registration roller 12.

  A conveyance mechanism (an example of a “conveyance unit”) 7 is for conveying the sheet 15, and is detachably attached to a predetermined attachment part (not shown) formed in the printer 1, for example. The transport mechanism 7 includes a driving roller 31, a driven roller 32, and a belt 34, and the belt 34 is bridged between the driving roller 31 and the driven roller 32. When the driving roller 31 rotates, the surface of the belt 34 facing the photosensitive drum 42 moves from the right direction to the left direction in FIG. As a result, the sheet 15 sent from the registration roller 12 is conveyed below the image forming unit 5. The transport mechanism 7 includes four transfer rollers 33.

  The image forming unit 5 includes four process units 40Y, 40M, 40C, and 40K and four exposure apparatuses 43. Each process unit 40 includes a charger 41, a photosensitive drum (an example of a “photosensitive member” and a “conveying unit”) 42, a drum cleaner roller (an example of a “cleaning unit”) 44, a paper dust removing roller (an “cleaning unit”). An example) 45, a unit case 46, a developing roller 47, and a supply roller 48 are included. Each process unit 40Y, 40M, 40C, 40K is detachably attached to a predetermined attachment portion (not shown) formed in the printer 1.

  For example, the photosensitive drum 42 is formed by forming a positively chargeable photosensitive layer on an aluminum substrate, and the aluminum substrate is grounded to the ground line of the printer 1 (see FIG. 2). . The charger 41 is, for example, a scorotron charger, and includes a discharge wire 41A and a grid 41B. The charging voltage CHG is applied to the discharge wire 41A, and the grid voltage GRID of the grid 41B is controlled so that the surface of the photosensitive drum 42 has substantially the same potential (for example, + 700V).

  The exposure device 43 includes, for example, a plurality of light emitting elements (for example, LEDs) arranged in a line along the rotational axis direction of the photosensitive drum 42, and the plurality of light emitting elements are selected according to image data input from the outside. By controlling the light emission, an electrostatic latent image is formed on the surface of the photosensitive drum 42. The exposure device 43 is fixedly installed in the printer 1. The exposure device 43 may use a laser.

  The unit case 46 stores toner of each color (in this embodiment, for example, a positively chargeable non-magnetic one-component toner), and includes a developing roller 47 and a supply roller 48. The toner is supplied to the developing roller 47 by the rotation of the supply roller 48 and is positively frictionally charged between the supply roller 48 and the developing roller 47. Further, the developing roller 47 supplies the toner as a uniform thin layer onto the photosensitive drum 42 to develop the electrostatic latent image, thereby forming a toner image on the photosensitive drum 42.

  Each transfer roller 33 is disposed at a position where the belt 34 is sandwiched between each transfer drum 33. Each transfer roller 33 receives a toner image formed on the photosensitive drum 42 by applying a transfer bias TRCC having a polarity opposite to the toner charging polarity (here, negative polarity) to the photosensitive drum 42. Transfer to the sheet 15. Thereafter, the sheet 15 is conveyed to the fixing unit 9 by the conveying mechanism 7, and the toner image is thermally fixed by the fixing unit 9 and is discharged onto the upper surface of the printer 1.

  A drum cleaning mechanism (corresponding to a “cleaning unit”) constituted by the drum cleaner roller 44 and the paper dust removing roller 45 removes the adhering matter (toner and paper dust) on the photosensitive drum 42 by electrostatic force. . The drum cleaning mechanism has two operation times for removing toner having positive polarity and paper powder having negative polarity. In the two operations, there are a toner suction executed at the time of printing (paper passing) and a toner discharge / paper dust suction executed after the print job is completed or after a predetermined number of sheets are printed (when paper is not passed). Including. Here, the paper dust removing roller 45 is provided only in the process unit 40K, for example.

  At the time of toner suction, toner is sucked from the photosensitive drum 42 to the drum cleaner roller 44. On the other hand, at the time of toner discharge and paper dust suction, the toner once sucked by the drum cleaner roller 44 is discharged to the photosensitive drum 42 and paper dust is removed from the photosensitive drum 42 via the drum cleaner roller 44. 45 is aspirated. For example, the toner discharged onto the photosensitive drum 42 is further discharged onto the belt 34 and is sucked and collected by the belt cleaning unit 20.

  The belt cleaning unit 20 is provided below the transport mechanism 7 and is detachably attached to a predetermined attachment portion (not shown). The belt cleaning unit 20 includes a belt cleaning roller 21, a deposit collection roller 22, and a collection box 23, and collects deposits (mainly toner remaining on the belt 34) on the belt 34.

  A photosensor (an example of a paper dust detection unit) 13 including a light emitting element and a light receiving element (not shown) is provided at a position facing the photosensitive drum 42 in the printer 1. The photosensor 13 emits light from the light emitting element to the photosensitive drum 42, and generates a light reception signal Sd based on the amount of light received from the photosensitive drum 42 (the amount of reflected light) by the light receiving element.

2. Configuration of High Voltage Power Supply Device Next, an electrical configuration related to the present invention of the printer 1 will be described with reference to FIG. FIG. 2 shows a schematic block diagram of a high-voltage power supply device 50 mounted on a circuit board (not shown) and a connection configuration related to the high-voltage power supply device 50. The high-voltage power supply device 50 includes voltage generation circuits corresponding to the process units 40Y, 40M, 40C, and 40K, but the configuration corresponding to each process unit is almost the same. Only the voltage generation circuit associated with 40K is shown.

  The high-voltage power supply device 50 includes a CPU 60, a plurality of voltage generation circuits connected to the CPU 60, a motor drive circuit 58, a ROM 61, and a RAM 62. The CPU 60 controls the entire printer in addition to controlling the voltage generation circuit. The ROM 61 stores an operation program for the entire printer, and the RAM 62 stores image data used for printing processing.

  The CPU 60 controls the photosensor 13 and detects the amount of paper dust adhering to the photosensitive drum 42 based on the light reception signal Sd from the photosensor 13. Then, the CPU 60 changes the cleaning time for removing the paper dust by the cleaning unit according to the detected amount of paper dust. That is, the CPU 60 is an example of a paper dust detection unit and a change unit.

  For example, as shown in FIG. 2, the plurality of voltage generation circuits include a charging voltage generation circuit 51, a paper dust removal bias / drum cleaner bias generation circuit 52, a transfer bias generation circuit 53, a development bias generation circuit 54, and a supply roller bias. A generation circuit 55, a belt cleaner bias generation circuit 56, and a deposit recovery bias generation circuit 57 are included.

  The charging voltage generation circuit 51 generates a charging voltage CHG applied to the discharge wire 41A of the charger 41 and a grid voltage GRID applied to the grid 41B of the charger 41. Here, the charging voltage CHG is, for example, 5.5 kV to 8 kV (positive polarity), and the grid voltage GRID is, for example, about 700 V (positive polarity). Here, the grid voltage GRID is a distribution of the charging voltage CHG by, for example, a discharge resistance during discharge between the discharge wire 41A and the grid 41B and a voltage dividing resistor provided in the charging voltage generation circuit 51. Generated by pressure.

  The charging voltage generation circuit 51 generates the charging voltage CHG in accordance with, for example, a PWM signal from the PWM1 port of the CPU 60, and the charging voltage CHG is feedback controlled via the A / D1 port.

  A paper dust removing bias / drum cleaner bias generating circuit (corresponding to a “cleaning unit”) 52 is configured to apply a paper dust removing bias DCLNB applied to the paper dust removing roller 45 and a drum cleaner bias (“cleaning”) to the drum cleaner roller 44. DCLNA (corresponding to “bias”) is generated. Here, the paper dust removal bias DCLNB is, for example, about 100 V (positive polarity) during toner suction, and is, for example, about 800 V (positive polarity) during toner discharge / paper powder suction.

  The drum cleaner bias DCLNA is, for example, about −100 V (negative polarity) at the time of toner suction, and is about 600 V (positive polarity) at the time of toner discharge / paper powder suction. In this embodiment, the paper dust removal bias / drum cleaner bias generation circuit 52 generates a paper dust removal bias DCLNB in accordance with the PWM signal from the PWM2 port of the CPU 60, and the drum cleaner bias DCLNA is based on the paper dust removal bias DCLNB. Is generated. The paper dust removal bias DCLNB is feedback controlled via the A / D2 port. The drum cleaner bias DCLNA and the paper dust removal bias DCLNB may be individually generated by individual voltage generation circuits.

  The transfer bias generation circuit 53 generates a transfer bias TRCC to be applied to the transfer roller 33. Here, the transfer bias TRCC is, for example, about −7 kV (negative polarity). The transfer bias generation circuit 53 generates a transfer bias TRCC in accordance with, for example, a PWM signal from the PWM3 port of the CPU 60, and the transfer bias TRCC is feedback controlled via the A / D3 port.

  The development bias generation circuit 54 generates a development bias DEV to be applied to the development roller 47. Here, the developing bias DEV is, for example, about 400 to 550 V (positive polarity). For example, the development bias generation circuit 54 generates a development bias DEV in accordance with a PWM signal from the PWM4 port of the CPU 60, and the development bias DEV is feedback-controlled through the A / D4 port.

  The supply roller bias generation circuit 55 generates a supply roller bias SR to be applied to the supply roller 48. Here, the supply roller bias SR is, for example, about 500 to 650 V (positive polarity). The supply roller bias generation circuit 55 generates the supply roller bias SR according to, for example, a PWM signal from the PWM5 port of the CPU 60, and the supply roller bias SR is feedback controlled via the A / D5 port.

  The belt cleaner bias generation circuit 56 generates a belt cleaner bias BCLNA to be applied to the belt cleaner roller 21. Here, the belt cleaner bias BCLNA is, for example, about −1200 V (negative polarity). The belt cleaner bias generation circuit 56 generates a belt cleaner bias BCLNA according to, for example, a PWM signal from the PWM6 port of the CPU 60, and the belt cleaner bias BCLNA is feedback-controlled through the A / D6 port.

  The deposit collection bias generation circuit 57 generates a deposit collection bias BCLNB to be applied to the deposit collection roller 22. Here, the deposit recovery bias BCLNB is, for example, about −1600 V (negative polarity). For example, the deposit collection bias generation circuit 57 generates the deposit collection bias BCLNB according to a PWM signal from the PWM7 port of the CPU 60, and the deposit collection bias BCLNB is feedback-controlled through the A / D7 port.

  The motor drive circuit 58 drives the main motor 14 according to the control of the CPU 60. Each roller is controlled to rotate in accordance with the rotation control of the main motor 14.

3. Paper Powder Removal Process Next, the paper powder removal process in the first embodiment will be described with reference to FIG. FIG. 3 is a flowchart showing the paper dust removal process. The paper dust removal process is executed by the CPU 60 according to a predetermined program, for example. In the paper dust removal process, for example, in accordance with a printing instruction from the user, cleaning before printing (corresponding to “first cleaning”) for removing the developer attached to the photosensitive drum 42 is performed, and then printing is performed. It is executed after the end of printing.

  In the paper dust removal process (corresponding to “second cleaning”), the CPU 60 first sets the number of rotations X of the photosensitive drum 42 to “0” and sets the number N of cleanings of the photosensitive drum 42 to “3”. (Step S110). Here, the number of rotations X is a numerical value indicating how many times the photosensitive drum 42 has rotated. Next, each high voltage (drum cleaner bias DCLNA, charging voltage CHG, developing bias DEV, transfer bias TRCC) is applied at a predetermined timing (step S120). Here, the predetermined charging voltage CHG and the developing bias DEV are applied to prevent the toner (developer) discharged to the photosensitive drum 42 during cleaning from adhering to the photosensitive drum 42. The transfer bias TRCC is applied to collect the toner discharged onto the photosensitive drum 42 during cleaning.

  Next, the CPU 60 causes the light emitting unit of the photosensor 13 to emit light, receives the light reception signal Sd from the photosensor 13, and acquires the amount of paper dust attached to the photosensitive drum 42 based on the light reception signal Sd. It is assumed that the relationship between the light reception signal Sd and the amount of paper dust is obtained in advance through experiments or the like, and a table indicating the relationship between the light reception signal Sd and the amount of paper dust is stored in the ROM 61 or the like. The CPU 60 acquires the amount of paper dust by referring to the table (step S130).

  Next, the CPU 60 determines whether or not the number of rotations X of the photosensitive drum 42 is “N”, that is, smaller than “3” (step S140). When it is determined that the number of rotations X of the photosensitive drum 42 is not smaller than “3” (step S140: NO), that is, when it is determined that the number of rotations X of the photosensitive drum 42 is “3”, the paper dust removal process is performed. Assuming the completion, the output of each high voltage is stopped (step S145).

  On the other hand, if it is determined that the number of rotations X of the photosensitive drum 42 is smaller than “3” (step S140: YES), the CPU 60 controls the motor driving circuit 58 to rotate the main motor 14 and rotate the photosensitive drum 42. . Then, when the cleaning of the photosensitive drum 42 is completed, that is, when the photosensitive drum 42 makes one rotation (step S150: YES), the rotation number X of the photosensitive drum 42 is incremented. That is, the number of rotations X of the photosensitive drum 42 is changed from “0” to “1” (step S155).

  Next, the CPU 60 acquires the amount of paper dust again (step S160). Then, it is determined whether or not the amount of paper dust acquired again, that is, the amount of paper dust remaining that cannot be removed by one cleaning, is greater than a predetermined amount of paper dust (step S170). When it is determined that the remaining paper dust amount is not larger than the predetermined paper dust amount (step S170: NO), the process returns to step S140.

  On the other hand, when it is determined that the remaining paper dust amount is larger than the predetermined paper dust amount (step S170: YES), the cleaning count N is incremented in step S180, that is, the cleaning count N is set to “4” (step S180). ). Then, the process returns to step S140. Here, the predetermined amount of paper dust is, for example, the amount of paper dust that can be removed to the desired amount of paper dust by two subsequent cleanings. Therefore, if the paper dust cannot be removed up to the desired amount of paper dust by the last two cleaning times, that is, a total of three cleanings, the photosensitive drum 42 is rotated four times or more, and the cleaning is performed four times or more. The

  In this embodiment, the initial value of the cleaning count N is set to “3”. However, the initial value is not limited to this, and can be arbitrarily set according to the installation status of the printer 1. In the cleaning before printing, an example is shown in which only the first cleaning for removing the developer is performed. However, the present invention is not limited to this. In the cleaning before printing, the second cleaning for removing paper dust is performed together with the first cleaning. It may be. That is, the paper dust removal process may be performed before printing.

4). Effects of First Embodiment When the amount of paper dust is larger than a predetermined amount, the number of rotations X of the photosensitive drum 42 during cleaning is changed so as to be larger than the predetermined number of rotations. Therefore, even if the amount of paper dust attached to the photosensitive drum 42 is large, the paper dust can be appropriately removed by increasing the number of rotations X of the photosensitive drum 42. That is, by changing the number of rotations X of the photosensitive drum 42, the cleaning time can be changed according to the amount of paper dust, and therefore paper dust can be removed appropriately.

  Further, the amount of paper dust is detected after the pre-printing cleaning (first cleaning) for removing the developer attached to the photosensitive drum 42 is completed. Therefore, the cleaning time for removing the paper dust can be set to a time required for removing only the paper dust that has not been removed by the first cleaning, and as a result, the cleaning time can be shortened.

<Embodiment 2>
Next, Embodiment 2 will be described with reference to FIG. FIG. 4 is a flowchart showing the paper dust removal process in the second embodiment. The second embodiment is different from the first embodiment only in the paper dust removing process. Therefore, only the paper dust removing process of the second embodiment will be described here. In that case, the same member number is attached to the same member as that of the first embodiment, and the description thereof is omitted. Further, the description of the same processing as that of the first embodiment is simplified.

  The paper dust removal process of the second embodiment is executed by the CPU 60 according to a predetermined program, for example, as in the first embodiment. Further, in accordance with a printing instruction from the user, pre-printing cleaning (corresponding to “first cleaning”) for removing the developer attached to the photosensitive drum 42 is performed, and then printing is performed. The photo sensor 13 is controlled to detect the amount of paper dust. Then, when the amount of paper dust is larger than the predetermined amount, the paper dust removing process of the second embodiment is executed. If the amount of paper dust is not greater than the predetermined amount, for example, the paper dust removal process of the first embodiment is executed.

  In the paper dust removal process (corresponding to “second cleaning”) of the second embodiment, the CPU 60 first changes the setting of the drum cleaner bias DCLNA to “H_BIAS” that is higher than the normal reference voltage value “N_BIAS” (step). S210). Next, the CPU 60 sets the number of rotations X of the photosensitive drum 42 to “0”, and sets the number N of cleanings of the photosensitive drum 42 to “2” (step S220). Next, each high voltage (drum cleaner bias DCLNA, charging voltage CHG, developing bias DEV, transfer bias TRCC) is applied at a predetermined timing (step S230).

  Next, the CPU 60 determines whether or not the rotation number X of the photosensitive drum 42 is smaller than “N”, that is, “2” (step S240). When it is determined that the number of rotations X of the photosensitive drum 42 is smaller than “2” (step S240: YES), the CPU 60 controls the motor driving circuit 58 to rotate the main motor 14 and rotate the photosensitive drum 42. Then, when the cleaning of the photosensitive drum 42 is completed, that is, when the photosensitive drum 42 makes one rotation (step S250: YES), the rotation number X of the photosensitive drum 42 is incremented. That is, the number of rotations X of the photosensitive drum 42 is changed from “0” to “1” (step S260). Steps S250 and S260 are repeated until the number of rotations X becomes “2”.

  On the other hand, when it is determined that the number of rotations X of the photosensitive drum 42 is not smaller than “2” (step S240: NO), that is, when it is determined that the number of rotations X of the photosensitive drum 42 is “2”, paper dust removal is performed. Assuming that the processing is completed, the drum cleaner bias DCLNA is changed from “H_BIAS” to “L_BIAS” lower than the normal voltage “N_BIAS” (step S270).

  Next, the CPU 60 controls the motor drive circuit 58 to rotate the main motor 14 and rotate the photosensitive drum 42. When the cleaning of the photosensitive drum 42 has been completed, that is, when the photosensitive drum 42 has made one revolution (step S280: YES), the output of each high voltage is stopped (step S290). The period in which the drum cleaner bias DCLNA is set to “L_BIAS” is not limited to the period in which the photosensitive drum 42 makes one revolution, and may be a period in which at least the photosensitive drum 42 makes one revolution.

5. Effect of Embodiment 2 When the amount of paper dust is larger than a predetermined amount, the drum cleaner bias (cleaning bias) DCLNA is set higher than the reference value. When removing paper dust electrically, the suction power of paper dust increases as the cleaning bias increases. Therefore, even if the amount of paper dust is large, the number of rotations X of the photosensitive drum 42 is reduced by increasing the cleaning bias. In other words, paper dust can be appropriately removed by shortening the cleaning time.

  After the paper dust removal process (second cleaning) is completed, the drum cleaner bias DCLNA increased to “H_BIAS” is set to “L_BIAS” lower than the reference value “N_BIAS” for a period of one rotation of the photosensitive drum 42. Therefore, it is possible to prevent the photosensitive drum 42 from being appropriately charged by the drum cleaner bias DCLNA increased for removing paper dust.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.

  (1) In each of the above-described embodiments, the photosensitive drum 42 is used as the transport unit, and the paper dust attached to the photosensitive drum 42 is removed. However, the present invention is not limited to this. For example, the belt 34 may be used as a transport unit and paper dust attached to the belt 34 may be removed.

(2) In each of the above embodiments, an example in which the detection of the amount of paper dust is performed using the photosensor 13 (paper dust detection unit) has been described, but the present invention is not limited thereto. For example, the paper dust detection unit includes a voltage generation unit that generates a predetermined detection voltage, applies the detection voltage to the photosensitive drum 42 (conveyance unit), and based on the current value obtained by applying the detection voltage. The amount may be estimated.
When the paper dust increases, the resistance value due to the paper dust increases, so that the value of the current that flows by applying the detection voltage to the photosensitive drum 42 changes, and the current value and the amount of paper dust are correlated. Therefore, the amount of paper dust can be estimated from the current value. As the detection voltage, for example, the amount of paper dust can be easily estimated by using an existing transfer bias TRCC in the image forming apparatus.

  (3) In each of the above embodiments, the CPU 60 (paper dust detection unit) detects the first paper dust amount before image formation on the paper 15 and the second paper dust amount after image formation on the paper 15. The cleaning time may be changed based on the difference between the first paper dust amount and the second paper dust amount. In this case, the cleaning time can be changed to a time required to remove paper dust adhered by forming an image on the paper, and as a result, the cleaning time can be shortened.

(4) In each of the above embodiments, the cleaning unit has an example in which the paper dust removing roller is provided separately from the drum cleaner roller. However, the present invention is not limited to this, and the present invention has an individual paper dust removing roller. In addition, the present invention can be applied to a configuration in which the drum cleaner roller also serves to remove paper dust.

  DESCRIPTION OF SYMBOLS 1 ... Printer, 13 ... Photosensor, 42 ... Photosensitive drum, 44 ... Drum cleaner roller, 45 ... Paper dust removal roller, 52 ... Paper dust removal voltage and drum cleaner bias generation circuit, 60 ... CPU

Claims (9)

A transport unit for transporting a recording medium;
A paper dust detection unit for detecting the amount of paper dust adhering to the transport unit;
A cleaning section for removing the paper dust;
A changing unit that changes a cleaning time for removing the paper dust by the cleaning unit according to the amount of paper dust detected by the paper dust detecting unit;
An image forming apparatus comprising: The image forming apparatus according to claim 1.
A photoconductor is provided as the transport unit,
The cleaning unit removes the paper dust by cleaning the photoreceptor,
The changing unit is configured to change the cleaning time by changing the number of rotations of the photoconductor during cleaning to a number of rotations greater than a predetermined number of rotations when the amount of paper dust is greater than a predetermined amount. The image forming apparatus according to claim 1, wherein:
The cleaning unit removes the paper dust using a cleaning bias,
The changing unit is configured to change the cleaning time by setting the cleaning bias higher than a reference value when the amount of paper dust is larger than a predetermined amount. The image forming apparatus according to claim 3.
A photoconductor is provided as the transport unit,
The cleaning unit performs a first cleaning for removing the developer attached to the photoconductor and a second cleaning for removing the paper dust attached to the photoconductor after the first cleaning is completed.
The image forming apparatus, wherein the changing unit sets the cleaning bias to be lower than the reference value for at least a period in which the photosensitive member makes one round after the second cleaning is completed. The image forming apparatus according to claim 1, wherein:
The paper dust detection unit detects a first paper dust amount before image formation on the recording medium and a second paper dust amount after image formation on the recording medium,
The image forming apparatus, wherein the changing unit changes the cleaning time based on a difference between the first paper dust amount and the second paper dust amount. The image forming apparatus according to claim 1, wherein:
The cleaning unit performs a first cleaning to remove the developer attached to the transport unit;
The paper dust detection unit is an image forming apparatus that detects the amount of paper dust after the first cleaning is completed. The image forming apparatus according to claim 6.
A photoconductor is provided as the transport unit,
The cleaning unit removes the developer attached to the photoconductor in the first cleaning;
The paper dust detection unit is an image forming apparatus that detects the amount of paper dust adhered to the photoconductor after the first cleaning is completed. The image forming apparatus according to any one of claims 1 to 7,
The paper dust detector
A photosensor including a light emitting element and a light receiving element;
An image forming apparatus that irradiates the transport unit with light from the light emitting element and detects the amount of paper dust based on an amount of light received from the transport unit by the light receiving element. The image forming apparatus according to any one of claims 1 to 7,
The paper dust detector
Including a voltage generator for generating a predetermined detection voltage;
An image forming apparatus that applies the detection voltage to the transport unit and estimates the amount of paper dust based on a current value obtained by applying the detection voltage.

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