JP2019120784A - Image forming device and image forming system - Google Patents

Abstract

To suppress poor images attributable to the unevenness in resistance of an intermediate transfer belt and suppress the replacement period of the intermediate transfer belt from being delayed or unnecessarily quickened, even when the amount of use per day of the device is different.SOLUTION: The image forming device comprises: an image carrier; an intermediate transfer belt having an elastic layer, to which a toner image is transferred from the image carrier; an electricity conduction part capable of sending electricity to the intermediate transfer belt; and an output part for outputting replacement information for prompting the replacement of the intermediate transfer belt. The number of images formed from when the first use of the intermediate transfer belt started to when replacement information is outputted (steps S71-S77) is a first number when electricity is sent every day under a first operating condition in which case the amount of electricity sent from the electricity conduction part to the intermediate transfer belt in a day is greater than or equal to a prescribed quantity, and a second number, which is larger than the first number, when electricity is sent every day under a second operating condition in which case the amount of electricity sent from the electricity conduction part to the intermediate transfer belt in a day is less than a prescribed quantity.SELECTED DRAWING: Figure 16

Description

  The present invention relates to an image forming apparatus and an image forming system for forming an image on a recording material by an electrophotographic method, an electrostatic recording method, or the like.

  Conventionally, an electrophotographic image forming apparatus has been widely applied as a copying machine, a printer, a plotter, a facsimile, a multifunction machine having a plurality of functions of these, and the like. In this type of image forming apparatus, it is known that a toner image formed on a photosensitive drum as an image carrier is primarily transferred onto an intermediate transfer belt as an intermediate transfer member, and then secondarily transferred onto a recording material (sheet). ing. As this intermediate transfer belt, for example, one having a plurality of layers such as a substrate, an elastic layer, and a surface layer, and having a conductive agent added to the elastic layer to adjust it to a desired electric resistance value has become widespread.

  In such an image forming apparatus, the electrical resistance of the intermediate transfer belt or the transfer roller, the film thickness of the surface layer of the photosensitive drum, or the like changes with changes in the atmosphere environment such as temperature and humidity, or with prolonged use There is. For this reason, for example, an image forming apparatus has been developed in which a transfer voltage capable of providing an optimum transfer current is applied at a secondary transfer portion for performing secondary transfer from an intermediate transfer belt to a sheet (Patent Document 1) 1). As such a voltage determination method, ATVC control (Active Transfer Voltage Control) is known, and a secondary transfer voltage capable of providing an optimum secondary transfer current is set.

  However, in the intermediate transfer belt, it is known that the electrical resistance value increases with long-term use. Further, it is known that, with the increase of the resistance value, resistance unevenness in a minute area is generated. For this reason, even if the transfer voltage is corrected so that the optimum transfer current flows as in the above-described image forming apparatus, the transfer current is changed due to the uneven resistance in a minute area, so the pattern of uneven resistance is generated. There is a possibility that an image failure which causes a transfer failure occurs. Therefore, the image formation in which the minimum number of image formations in the range of the number of image formations in which image defects due to uneven resistance may occur is uniformly set as the number of life of the intermediate transfer belt which is the same product as that. An apparatus has been developed (see Patent Document 2). According to this image forming apparatus, when performing image formation for the set number of lifespans, occurrence of image defects is prevented by prompting the user that the intermediate transfer belt has reached the replacement time due to the lifespan. Can.

JP, 2015-222407, A JP 2007-304144 A

  Here, the inventor of the present application has investigated the number of image forming sheets on which image defects actually occur due to uneven resistance for the intermediate transfer belt for which the number of lifetimes described above is set. It was found that the number of sheets greatly changed depending on the amount (the amount of energization). For example, it has been found that a user who uses a large amount per day may have a smaller number of image formation sheets until the occurrence of an image failure caused by the above-mentioned uneven resistance compared to a user who does not use it a lot. On the other hand, in the image forming apparatus described in Patent Document 2 mentioned above, the life count of the intermediate transfer belt is uniformly set based on the total number of sheets for image formation without considering the usage amount per day, and the replacement is urged. The For this reason, for a user who uses a small amount per day, the intermediate transfer belt is uniformly replaced because the number of sheets for image formation has reached the end of the life despite the fact that there is a sufficient margin until an image failure actually occurs. It had been done. In addition, the exchange timing may be delayed for a user whose usage per day is extremely large.

  The present invention suppresses image defects caused by uneven resistance of the intermediate transfer belt even when the daily usage amount of the apparatus is different, and also delays the replacement time of the intermediate transfer belt or unnecessarily accelerates it. The purpose is to suppress.

  An image forming apparatus according to the present invention includes an image carrier, an intermediate transfer belt having an elastic layer, to which a toner image is transferred from the image carrier, a conductive portion capable of energizing the intermediate transfer belt, and the intermediate And an output unit for outputting replacement information for promoting replacement of the transfer belt, wherein the number of sheets for image formation from the time of first use of the intermediate transfer belt to the time of output of the replacement information is the current-carrying unit on one day The first number is the number of sheets when power is supplied continuously under the first operating condition in which the amount of power supplied to the intermediate transfer belt is equal to or greater than the predetermined amount, the first number of sheets. In the case where the current is supplied on a daily basis under the second operation condition in which the amount of current to be supplied is less than the predetermined amount, the second number is larger than the first number.

  Further, the image forming apparatus of the present invention includes an image carrier, an intermediate transfer belt having an elastic layer, to which a toner image is transferred from the image carrier, and a conducting portion capable of energizing the intermediate transfer belt. And an output unit for outputting replacement information for prompting replacement of the intermediate transfer belt, and the number of image forming sheets from the start of the first use of the intermediate transfer belt to the output of the replacement information is one day. This is the first number when images are formed daily under the first operation condition where the number of image formations to be performed is equal to or greater than a predetermined number, and the second number of images formed per day is less than the predetermined number. When images are formed daily under the operating conditions, the second number is larger than the first number.

  Further, the image forming system of the present invention includes an image carrier, an intermediate transfer belt having an elastic layer, to which a toner image is transferred from the image carrier, and a conducting portion capable of energizing the intermediate transfer belt. An image forming apparatus having a transmitting unit that transmits a value related to the amount of current supplied to the intermediate transfer belt from the conductive unit; and a value related to the amount of current transmitted by the transmitting unit that is communicable with the transmitting unit An information transmitting apparatus having a receiving unit for receiving and an output unit for outputting replacement information for prompting replacement of the intermediate transfer belt, and the exchange information from the time when the first use of the intermediate transfer belt is started The number of image formation up to the time of output is the first number when the current is supplied on a continuous basis under the first operating condition that the amount of current supplied to the intermediate transfer belt from the power supply part per day is equal to or greater than a predetermined amount. Yes, 1 day ago The second number of sheets, which is larger than the first number, is the number of sheets that are continuously supplied under the second operation condition in which the amount of current supplied to the intermediate transfer belt from the power supply unit is less than the predetermined amount. I assume.

  According to the present invention, even when the daily usage amount of the apparatus is different, it is possible to suppress the image defect caused by the uneven resistance of the intermediate transfer belt and to delay the replacement time of the intermediate transfer belt or to accelerate unnecessaryly. Can be suppressed.

FIG. 1 is a cross-sectional view showing a schematic configuration of an image forming apparatus according to a first embodiment. FIG. 2 is a block diagram showing a schematic configuration of a control system of the image forming apparatus according to the first embodiment. 5 is a flowchart showing a control procedure of a primary transfer voltage in the image forming apparatus according to the first embodiment. FIG. 2 is an explanatory view showing a schematic configuration of a belt cleaning device of the image forming apparatus according to the first embodiment. 5 is a graph showing the relationship between the number of sheets on which an image is formed and the volume resistivity of the intermediate transfer belt in the image forming apparatus according to the first embodiment. 5 is a graph showing the relationship between the number of sheets for image formation and the primary transfer voltage in the image forming apparatus according to the first embodiment, wherein (a) is a voltage value of each color, and (b) is a voltage difference between black and yellow. 7 is a flowchart showing a display procedure of a replacement alarm immediately after power on in the image forming apparatus according to the first embodiment. 5 is a flowchart showing a display procedure of a replacement alarm after inter-sheet ATVC control in the image forming apparatus according to the first embodiment. In the image forming apparatus according to the first embodiment, it is a graph showing the relationship between the date of one week and the voltage difference between black and yellow. It is a flowchart which shows the display procedure of the replacement | exchange alarm in monochrome mode in the image forming apparatus which concerns on 2nd Embodiment. 14 is a graph showing the relationship between the number of sheets on which an image is formed, the voltage difference between black and yellow, and the voltage difference between cyan and yellow in the image forming apparatus according to the third embodiment. It is a flowchart which shows the display procedure of the exchange alarm immediately after the power supply ON in the image forming apparatus which concerns on 3rd Embodiment. It is a graph which shows the relationship of the number of image formations and cleaning voltage in the image forming apparatus which concerns on 4th Embodiment, (a) is each cleaning voltage, (b) is a voltage difference of each cleaning voltage. It is a flowchart which shows the display procedure of the replacement | exchange alarm after the image formation completion in the image forming apparatus which concerns on 4th Embodiment. In the image forming apparatus according to the fifth embodiment, (a) shows the relationship between the number of image formation and the voltage difference between black and yellow, and (b) shows the relationship between the number of image formation per day and the voltage difference between black and yellow. Is a graph showing It is a flowchart which shows the display procedure of the replacement | exchange alarm after the image formation completion in the image forming apparatus which concerns on 5th Embodiment. It is a flowchart which shows the display procedure of the replacement | exchange alarm after the completion of image formation in the image forming apparatus which concerns on 6th Embodiment. It is a flow chart which shows the display procedure of the exchange alarm after the end of image formation in the image forming device concerning a 7th embodiment. It is a flow chart which shows the display procedure of the exchange alarm after the end of image formation in the image forming device concerning an 8th embodiment. It is a flow chart which shows the display procedure of the exchange alarm after the end of image formation in the image forming device concerning a 9th embodiment. It is a flow chart which shows the display procedure of the exchange alarm after the end of image formation in the image forming device concerning a 10th embodiment. It is a flow chart which shows the display procedure of the exchange alarm after the end of image formation in the image forming device concerning an 11th embodiment. It is a flow chart which shows the display procedure of the exchange alarm after the end of image formation in the image forming device concerning a 12th embodiment. It is a system configuration | structure figure which shows the structure of the image forming system in the image forming system which concerns on 13th Embodiment.

First Embodiment
Hereinafter, a first embodiment of the present invention will be described in detail with reference to FIGS. 1 to 9. In the present embodiment, a tandem-type full-color printer is described as an example of the image forming apparatus 1. However, the present invention is not limited to the tandem-type image forming apparatus 1, and may be another type of image forming apparatus, and is not limited to full-color, and may be monochrome or mono-color. Alternatively, the present invention can be implemented in various applications such as printers, various printing machines, copying machines, fax machines, multifunction machines and the like.

  As shown in FIG. 1, the image forming apparatus 1 includes an apparatus main body 10, a sheet feeding unit (not shown), an image forming unit 40, a sheet discharging unit (not shown), a control unit 30, and an operation unit 70 See FIG. 2). Inside the device main body 10, a temperature sensor 71 (see FIG. 2) capable of detecting the temperature inside the device and a humidity sensor 72 (see FIG. 2) capable of detecting the humidity inside the device are provided. The image forming apparatus 1 can form a full-color image of four colors on a recording material according to an image signal from an unshown original reading device or a host device such as a personal computer, or an external device such as a digital camera or a smartphone. . The sheet S as a recording material is a sheet on which a toner image is formed, and specific examples thereof include a plain paper, a synthetic resin sheet which is a substitute for the plain paper, a thick sheet, a sheet for an overhead projector, and the like.

  The image forming unit 40 can form an image on the sheet S fed from the sheet feeding unit based on the image information. The image forming unit 40 includes image forming units 50y, 50m, 50c and 50k, toner bottles 41y, 41m, 41c and 41k, exposure devices 42y, 42m, 42c and 42k, an intermediate transfer unit 44, and a secondary transfer device. 45 and a fixing unit 46. The image forming apparatus 1 of the present embodiment corresponds to full color, and the image forming units 50y, 50m, 50c and 50k are yellow (y), magenta (m), cyan (c) and black (k). Each of the four colors is separately provided in the same configuration. For this reason, although a color identifier is attached after the same sign for each configuration of four colors in FIG. 1, the description may be made using only the code without a color identifier in the specification. The image forming apparatus 1 can also form a single-color or multi-color image using an image forming unit 50 for a desired single color or some of four colors, such as a black single-color image. It is.

  The image forming unit 50 includes a photosensitive drum (image carrier) 51 that carries and moves a toner image, a charging roller 52, a developing device 20, a pre-exposure device 54, and a cleaning blade 55. . The image forming unit 50 is integrally united as a process cartridge, configured to be detachable from the apparatus main body 10, and forms a toner image on an intermediate transfer belt 44b described later.

  The photosensitive drum 51 is rotatable and carries an electrostatic image used for image formation. In the present embodiment, the photosensitive drum 51 is a negatively chargeable organic photosensitive member (OPC) with an outer diameter of 30 mm, and is rotationally driven by a motor (not shown) in the arrow direction at a predetermined process speed (peripheral speed). The photosensitive drum 51 has an aluminum cylinder as a base, and has three layers of an undercoat layer, a photocharge generation layer, and a charge transport layer, which are sequentially applied and laminated on the surface as a surface layer. In the present embodiment, the yellow photosensitive drum 51y carries the toner image and moves, and contacts the intermediate transfer belt 44b to form a first primary transfer portion 48y with the intermediate transfer belt 44b. The first image carrier is used. The black photosensitive drum 51k is disposed at a different position along the rotational direction of the intermediate transfer belt 44b with respect to the yellow photosensitive drum 51y. A second image carrier which moves the black photosensitive drum 51k to carry a toner image and abuts against the intermediate transfer belt 44b to form a second primary transfer portion 48k with the intermediate transfer belt 44b. And In the present embodiment, the plurality of photosensitive drums 51 including the black photosensitive drum 51k and the yellow photosensitive drum 51y are provided at different positions along the rotation direction of the intermediate transfer belt 44b. The photosensitive drums 51k for black and the photosensitive drums 51y for yellow are two photosensitive drums 51 disposed among the plurality of photosensitive drums 51 most distantly along the rotational direction.

  The charging roller 52 is in contact with the surface of the photosensitive drum 51 and uses a rubber roller that rotates in a driven manner, and uniformly charges the surface of the photosensitive drum 51. A charging bias power supply 73 (see FIG. 2) is connected to the charging roller 52. The charging bias power supply 73 applies a DC voltage as a charging bias to the charging roller 52 and charges the photosensitive drum 51 via the charging roller 52. The exposure device 42 is a laser scanner, and emits laser light according to the image information of the separated color output from the control unit 30.

  The developing device 20 develops the electrostatic image formed on the photosensitive drum 51 with toner by applying a developing bias. The developing device 20 has a developing sleeve 24. The developing device 20 stores the developer supplied from the toner bottle 41 and develops the electrostatic image formed on the photosensitive drum 51. The developing sleeve 24 is made of, for example, a nonmagnetic material such as aluminum or nonmagnetic stainless steel, and is made of aluminum in the present embodiment. Inside the developing sleeve 24, a roller-shaped magnet roller is fixedly installed in a non-rotating state with respect to the developing container. The developing sleeve 24 carries a developer having nonmagnetic toner and magnetic carrier, and conveys it to a developing area facing the photosensitive drum 51. A developing bias power supply 74 (see FIG. 2) is connected to the developing sleeve 24. The developing bias power supply 74 applies a DC voltage as a developing bias to the developing sleeve 24 and develops the electrostatic image formed on the photosensitive drum 51.

  The toner image developed on the photosensitive drum 51 is primarily transferred to the intermediate transfer unit 44. The surface of the photosensitive drum 51 after the primary transfer is neutralized by the pre-exposure device 54. The cleaning blade 55 is a counter blade type, and is in contact with the photosensitive drum 51 with a predetermined pressing force. After the primary transfer, the toner remaining on the photosensitive drum 51 without being transferred to the intermediate transfer unit 44 is removed by the cleaning blade 55 provided in contact with the photosensitive drum 51 to prepare for the next image forming process.

  The intermediate transfer unit 44 includes a plurality of rollers such as a drive roller 44a, a driven roller 44d, and primary transfer rollers 47y, 47m, 47c, and 47k, and an intermediate transfer belt which is wound around these rollers and carries a toner image. And 44b. The driven roller 44d is a tension roller adapted to control the tension of the intermediate transfer belt 44b constant. The driven roller 44d is applied with a force that pushes the intermediate transfer belt 44b to the surface side by the biasing force of a biasing spring (not shown), and this force causes a tension of about 2 to 5 kg in the conveyance direction of the intermediate transfer belt 44b. It is hung.

Primary transfer rollers (primary transfer means) 47y, 47m, 47c and 47k are disposed to face the photosensitive drums 51y, 51m, 51c and 51k, respectively. The primary transfer roller 47 is disposed to sandwich the intermediate transfer belt 44 b with the photosensitive drum 51, and a toner image formed on the surface of the photosensitive drum 51 at the primary transfer portion 48 by applying a primary transfer voltage. Primary transfer to the intermediate transfer belt 44b. A primary transfer power supply 75 (see FIG. 2) is connected to the primary transfer roller 47. Connected to the primary transfer power supply 75 are a voltage detection sensor 75a for detecting an output voltage and a current detection sensor 75b for detecting an output current (see FIG. 2). The primary transfer power sources 75y, 75m, 75c and 75k are provided on the primary transfer rollers 47y, 47m, 47c and 47k, respectively, and the primary transfer voltage applied to the primary transfer rollers 47y, 47m, 47c and 47k is It is individually controllable. The primary transfer roller 47 has, for example, an outer diameter of 15 to 20 mm, and has an elastic layer of ion conductive foam rubber (NBR rubber) and a core metal. As the primary transfer roller 47, a roller having a resistance value of 1 × 10 ⁵ to 1 × 10 ⁸ Ω (N / N (23 ° C., 50% RH) measurement, 2 kV applied) is used. In the present embodiment, the yellow primary transfer power supply 75y is a first energizing unit, and the black primary transfer power supply 75k is a second energizing unit. The yellow primary transfer power supply 75y applies a first primary transfer voltage to the yellow primary transfer portion 48y. The black primary transfer power supply 75k applies a second primary transfer voltage to the black primary transfer portion 48k.

  The intermediate transfer belt 44 b is rotatable, and rotates at a predetermined speed in the direction of the arrow. The intermediate transfer belt 44 b contacts the photosensitive drum 51 to form a primary transfer portion 48 with the photosensitive drum 51. The primary transfer voltage is applied from the primary transfer power source 75 (see FIG. 2) to the primary transfer portion 48, whereby the toner image formed on the photosensitive drum 51 is primarily transferred by the primary transfer portion 48. By applying a primary transfer voltage of positive polarity to the intermediate transfer belt 44b by the primary transfer roller 47, toner images having respective negative polarities on the photosensitive drum 51 are sequentially multiple-transferred onto the intermediate transfer belt 44b.

The intermediate transfer belt 44 b is an endless belt having a three-layer structure of a base layer, an elastic layer, and a surface layer from the back surface side. That is, the intermediate transfer belt 44 b has an elastic layer, and the toner image is transferred from the photosensitive drum 51. As the resin material constituting the base layer, a material such as a resin such as polyimide or polycarbonate, or various rubbers containing an appropriate amount of carbon black as an antistatic agent is used, and the thickness of the base layer is 0.05-0. It is 15 [mm]. As an elastic material constituting the elastic layer, a material in which an appropriate amount of an ion conductive agent is contained in various rubbers such as urethane rubber and silicone rubber is used, and the thickness of the elastic layer is 0.1 to 0.500 [ mm]. The material constituting the surface layer is a resin such as fluorocarbon resin, and the adhesion of the toner to the surface of the intermediate transfer belt 44b is reduced to facilitate transfer of the toner to the sheet S at the secondary transfer nip N. The thickness is 0.0002 to 0.020 mm. In the present embodiment, the surface layer uses, for example, one type of resin material such as polyurethane, polyester, epoxy resin, or two or more types of elastic materials such as elastic rubber, elastomer, butyl rubber, etc. . Then, as a material for reducing surface energy and enhancing lubricity with respect to this base material, for example, powder or particles of fluorine resin or the like are dispersed by dispersing one or more kinds of particles or particles, or different particle sizes, Form a surface. In the intermediate transfer belt 44b of this embodiment, the volume resistivity is 5 × 10 ⁸ to 1 × 10 ¹⁴ [Ω · cm] (23 ° C., 50% RH), and the hardness is 60 to 85 ° (23 ° in MD1 hardness). ° C, 50% RH). The static friction coefficient is 0.15 to 0.6 (23 ° C., 50% RH, type 94i manufactured by HEIDON).

  The secondary transfer device 45 includes a secondary transfer inner roller 45a and a secondary transfer outer roller (secondary transfer means) 45b. The secondary transfer inner roller 45a is disposed to face the secondary transfer outer roller 45b via the intermediate transfer belt 44b. A secondary transfer power supply 76 (see FIG. 2) is connected to the secondary transfer outer roller 45b. Connected to the secondary transfer power supply 76 are a voltage detection sensor 76a for detecting an output voltage and a current detection sensor 76b for detecting an output current (see FIG. 2).

  The secondary transfer power supply 76 applies a DC voltage as a secondary transfer voltage to the secondary transfer outer roller 45b. The secondary transfer outer roller 45b abuts against the intermediate transfer belt 44b to form a nip portion (secondary transfer portion) N with the intermediate transfer belt 44b. When a secondary transfer voltage having a polarity opposite to that of the toner is applied to the nip portion N, the secondary transfer outer roller 45b supplies the toner image, which has been primarily transferred and carried on the intermediate transfer belt 44b, to the nip portion N. The sheet is secondarily transferred onto the sheet S at once. The core of the secondary transfer inner roller 45a is connected to the ground potential. When the sheet S is supplied to the secondary transfer device 45, a constant voltage controlled secondary transfer voltage of reverse polarity to the toner image is applied to the secondary transfer outer roller 45b. In the present embodiment, for example, a secondary transfer voltage of 1 to 7 kV is applied, a current of 40 to 120 μA is applied, and the toner image on the intermediate transfer belt 44 b is secondarily transferred to the sheet S. In the present embodiment, the secondary transfer power supply 76 applies the DC voltage to the secondary transfer outer roller 45b to apply the secondary transfer voltage to the nip N. Is not limited. For example, the secondary transfer voltage may be applied to the nip portion N by applying a DC voltage to the secondary transfer inner roller 45a.

The secondary transfer outer roller 45b has, for example, an outer diameter of 20 to 25 mm, and includes an elastic layer of ion conductive foam rubber (NBR rubber) and a core metal. As the secondary transfer outer roller 45b, a roller having a resistance value of 1 × 10 ⁵ to 1 × 10 ⁸ Ω (N / N (23 ° C., 50% RH) measurement, 2 kV applied) is used.

  Further, the intermediate transfer unit 44 has a belt cleaning device 60. The belt cleaning device 60 removes deposits such as toner remaining on the intermediate transfer belt 44b after the secondary transfer process. The detailed configuration of the belt cleaning device 60 will be described later. Further, in the present embodiment, the primary transfer power supply 75, the secondary transfer power supply 76, and the cleaning power supplies 61e and 62e to be described later constitute an energizing unit capable of energizing the intermediate transfer belt 44b.

  The fixing unit 46 includes a fixing roller 46 a and a pressure roller 46 b. The sheet S is nipped and conveyed between the fixing roller 46 a and the pressure roller 46 b, whereby the toner image transferred to the sheet S is heated and pressed, and is fixed to the sheet S. The temperature of the fixing roller 46a is detected by a fixing temperature sensor 77 (see FIG. 2). The sheet discharge unit feeds the sheet S conveyed from the discharge path after fixing, for example, discharges it from the discharge port and stacks it on the discharge tray. Further, between the fixing unit 46 and the discharge port, a reverse conveying path (not shown) capable of passing the secondary transfer device 45 again by turning over the sheet after fixing is provided. By the operation of the reverse conveyance path, image formation can be realized on both sides of one sheet.

  As shown in FIG. 2, the control unit 30 is constituted by a computer, and for example, a CPU 31, a ROM 32 for storing programs for controlling the respective units, a RAM 33 for temporarily storing data, and an input / output for inputting / outputting signals to / from outside. And a circuit (I / F) 34. The CPU 31 is a microprocessor that controls the entire control of the image forming apparatus 1 and is a main body of a system controller. The CPU 31 is connected to the sheet feeding unit, the image forming unit 40, the sheet discharging unit, and the operation unit 70 via the input / output circuit 34, exchanges signals with each unit, and controls the operation. The ROM 32 stores an image formation control sequence and the like for forming an image on the sheet S. The control unit 30 is connected to a charge bias power supply 73, a development bias power supply 74, a primary transfer power supply 75, and a secondary transfer power supply 76, and is controlled by signals from the control unit 30, respectively. The control unit 30 also includes a temperature sensor 71, a humidity sensor 72, a voltage detection sensor 75a and a current detection sensor 75b of the primary transfer power supply 75, a voltage detection sensor 76a and a current detection sensor 76b of the secondary transfer power supply 76, and a fixing temperature sensor. 77 are connected. Furthermore, the control unit 30 includes cleaning power supplies 61e and 62e of the belt cleaning device 60 described later, a first voltage detection sensor 61f and a first current detection sensor 61g, a second voltage detection sensor 62f and a second The current detection sensor 62g is connected. A signal detected by each sensor is input to the control unit 30.

  The operation unit 70 includes an operation button and a display unit 70 a including a liquid crystal panel or the like. The user can execute a print job by operating the operation unit 70, and the control unit 30 operates various devices of the image forming apparatus 1 in response to a signal from the operation unit 70. The display unit 70a can display various settings and states, and also receives exchange information for prompting replacement of the intermediate transfer belt 44b output from the control unit 30, and information on replacement of the intermediate transfer belt 44b. Display the replacement alarm as.

  In the present embodiment, the control unit 30 includes an image formation preparation process unit 31a, an ATVC control process unit 31b, and an image formation process unit 31c. Further, the control unit 30 includes a primary transfer voltage storage unit / operation unit 31d, a cleaning voltage storage unit / operation unit 31e, a secondary transfer voltage storage unit / operation unit 31f, and an image formation counter storage unit / operation unit 31g. , Timer storage unit / operation unit 31 h. The respective process units and the storage unit / arithmetic unit may be provided as part of the CPU 31 or the RAM 33. The control unit 30 applies a primary transfer voltage to the plurality of primary transfer portions 48 to form an image in a plurality of colors, and the primary transfer voltage only to one primary transfer portion 48 of the plurality of primary transfer portions 48. Can be switched between the single-color mode in which an image is formed in a single color by applying In the present embodiment, the control unit 30 can execute a full color mode (a plurality of color modes) in which a primary transfer voltage is applied to the four primary transfer portions 48 to form an image in full color (a plurality of colors). Further, the control unit 30 can execute the black and white mode (monochrome mode) in which the primary transfer voltage is applied only to the black primary transfer portion 48k to form an image in black (monochrome).

  The control unit 30 can also execute ATVC control (setting mode) for setting the first primary transfer voltage and the second primary transfer voltage. Details of ATVC control will be described later. Furthermore, in the control unit 30, the first cleaning power supply 61e applies a first cleaning voltage to the upstream device 61 (see FIG. 1), and the second cleaning power supply 62e is a downstream device 62 (see FIG. 1). It is possible to implement a cleaning mode in which a second cleaning voltage is applied. Details of the cleaning mode will be described later.

  The control unit 30 is an output unit and outputs replacement information for promoting replacement of the intermediate transfer belt 44b. In the present embodiment, for the reason to be described later, from the initial use of the intermediate transfer belt 44b to the output time of the exchange information prompting replacement by the daily usage amount (the number of images formed and the energization amount) of the image forming apparatus 1. The total number of image formations has been changed. For example, since the first use start when the intermediate transfer belt 44b is not in use, the first operation condition is such that the amount of current supplied from the power supply unit to the intermediate transfer belt 44b is 1 day or more. Consider the case where the image forming apparatus 1 is operated to make it possible. In this case, the control unit 30 is the first number of sheets on which images have been formed until the output of the exchange information for prompting replacement of the intermediate transfer belt 44b. On the other hand, the image forming apparatus 1 is energized continuously under a second operating condition in which the amount of energization of the intermediate transfer belt 44b from the energizing unit on one day is less than a predetermined amount from a state where the intermediate transfer belt 44b is not used. Consider the case of operation. In this case, the control unit 30 has the second number, which is larger than the first number, as the number of times of image formation until the output of the exchange information for prompting replacement of the intermediate transfer belt 44b.

  In other words, when images are formed continuously on the first day under the first operating condition that the number of image formation formed on one day is equal to or more than the predetermined number, the image formation up to the time of outputting exchange information prompting replacement of intermediate transfer belt 44b. The number is the first number. When images are formed continuously on the second day under the second operating condition that the number of image formations formed per day is less than the predetermined number, the number of image formations up to the time of outputting the exchange information prompting replacement of the intermediate transfer belt 44b is , And a second number more than the first number.

  Next, an image forming operation in the image forming apparatus 1 configured as described above will be described.

  When the image forming operation is started, first, the photosensitive drum 51 is rotated and the surface is charged by the charging roller 52. Then, laser light is emitted to the photosensitive drum 51 based on the image information by the exposure device 42, and an electrostatic latent image is formed on the surface of the photosensitive drum 51. By attaching toner to this electrostatic latent image, it is developed to be visualized as a toner image, and is transferred to the intermediate transfer belt 44b.

  On the other hand, the sheet S is supplied in parallel with the toner image forming operation, and the sheet S is conveyed to the secondary transfer device 45 through the conveyance path in synchronization with the toner image of the intermediate transfer belt 44 b. . Further, the image is transferred from the intermediate transfer belt 44b to the sheet S, and the sheet S is conveyed to the fixing unit 46, where the unfixed toner image is heated and pressed to be fixed on the surface of the sheet S. Discharged from

  Next, control of the primary transfer voltage will be described in detail with reference to FIGS. 2 and 3. Generally, control of the primary transfer voltage includes constant voltage control and constant current control. In the present embodiment, constant voltage control is used. Depending on the installation environment of the apparatus main body 10, a table of transfer current for each color is stored in the primary transfer voltage storage unit / calculation unit 31d. In this embodiment, the target current is 55 μA for all colors. At the primary transfer portion 48, a current flows from the primary transfer roller 47 in the thickness direction of the intermediate transfer belt 44b (direction from the primary transfer roller 47 to the photosensitive drum 51), so the resistance change of the primary transfer roller 47 and the intermediate transfer belt 44b The desired current does not flow if there is In order to correct this resistance change, a predetermined current is supplied at the time of power-on or before the image formation, and ATVC control is performed to measure the voltage.

  As shown in FIG. 3, when the power is turned on (step S1), the CPU 31 acquires the detection value of the fixing temperature sensor 77 and determines whether the fixing temperature is at least TL and not more than TU (step S1). S2). In the present embodiment, for example, TL = 160 ° C. and TU = 180 ° C. However, of course it is not limited to this. If the CPU 31 determines that the fixing temperature is not less than TL and not less than TU, an execution signal is input from the CPU 31 to the image formation preparation processing unit 31a, and preparation for image formation is performed (step S3). If the CPU 31 determines that the fixing temperature is equal to or higher than TL and equal to or lower than TU, the CPU 31 determines that the fixing temperature adjustment condition is satisfied (so-called during pre-rotation), and ATVC control (setting mode) is performed (a setting mode). Step S4).

  In the ATVC control, a signal is input from the CPU 31 to the ATVC control process unit 31b to charge the photosensitive drum 51 in the same manner as in the image forming process, apply multiple levels of voltages to each primary transfer roller 47, and Is detected by the current detection sensor 75b. From the relationship between the applied voltage and current, the transfer voltage Vtr is determined to be the target current to be output. In ATVC control, for example, a voltage of 2000 V is first applied to the primary transfer roller 47, and the current at that time is measured. If the current is smaller than the target current, next, apply a predetermined voltage higher than 2000 V, for example, 3000 V, and measure the current at that time. Then, the measurement results of the current at 2000 V and 3000 V are linearly approximated, and then a voltage value is obtained such that the target current, here 55 μA. The primary transfer voltage obtained here is used at the time of image formation. The voltage applied at this time is not limited to two levels, and three or more different voltages may be applied for measurement.

  Here, for example, it is assumed that the ATVC control process unit 31 b performs ATVC control of the yellow primary transfer unit 48 y. Then, it is assumed that the ATVC control process unit 31 b is set to apply the first primary transfer voltage so that the target current 55 μA flows from the primary transfer power supply 75 y. In this case, the voltage value of the set first primary transfer voltage is acquired and stored in the primary transfer voltage storage unit / calculation unit 31 d. That is, in the ATVC control, the control unit 30 sets a first primary transfer voltage to be applied so that the primary transfer power supply 75y causes the target current (first predetermined current) to flow to the yellow primary transfer portion 48y.

  Similarly, in the ATVC control process unit 31b, for example, it is assumed that ATVC control of the black primary transfer unit 48k is performed. In this case, when the primary transfer power supply 75y is energized, the energized area, which is the area of the intermediate transfer belt 44b that has passed the yellow primary transfer portion (first position) 48y, passes the black primary transfer portion (second position) 48k. At this time, the primary transfer power supply 75k energizes the intermediate transfer belt 44b. The control unit 30 obtains a first voltage and a first current of the yellow primary transfer power supply 75y when the yellow primary transfer unit 48y is energized. Further, the control unit 30 obtains the second voltage and the second current of the primary transfer power supply 75k at the time of energization when the energization region of the intermediate transfer belt 44b passes through the black primary transfer portion 48k. Then, the control unit 30 outputs exchange information based on the first voltage and the first current and the second voltage and the second current. Then, it is assumed that the ATVC control process unit 31 b is set to apply the second primary transfer voltage so that the target current 55 μA flows from the primary transfer power supply 75 k. In this case, the voltage value of the set second primary transfer voltage is acquired and stored in the primary transfer voltage storage unit / calculation unit 31 d. That is, in the ATVC control, the control unit 30 sets a second primary transfer voltage to be applied so that the primary transfer power supply 75k flows a target current (second predetermined current) to the black primary transfer portion 48k. Here, each primary transfer voltage is acquired from the ATVC control process unit 31b to the primary transfer voltage storage unit / calculation unit 31d, but the invention is not limited thereto, and the voltage detection sensor 75a may be used.

  Next, the CPU 31 determines whether there is a job signal (step S5). If the CPU 31 determines that there is no job signal, it becomes standby and waits for a job signal (step S6). If the CPU 31 determines that there is a job signal, it determines whether the elapsed time since the previous ATVC control has been performed is smaller than a predetermined elapsed time Δt (step S7). In this embodiment, Δt = 30 minutes, but it is not limited to this. The CPU 31 executes ATVC control (setting mode) when determining that the elapsed time since the previous execution of ATVC is not smaller than the predetermined elapsed time Δt (step S8). If the CPU 31 determines that the elapsed time since the previous ATVC control was performed is smaller than the predetermined elapsed time Δt, or after performing the ATVC control in step S8, a signal is input to the image forming process unit 31c. , Image formation is started (step S9).

  When the image formation is started, the CPU 31 determines whether the number of formed images is M or more (step S10). In this embodiment, M = 28 × N + 1 (N = 1, 2, 3,...). If the number of image formation is not M or more, the image formation is continued. If the number of sheets for image formation is M or more, voltage correction is performed between the sheets (step S11). That is, in the present embodiment, the current between the sheets is calculated every 28 sheets of image formation, and voltage correction is performed by adding or subtracting ΔV to the transfer voltage Vtr so far at the time of the subsequent image formation. In the present embodiment, the primary transfer current is a full environment, a full color, and a target current of 55 μA. However, the present invention is not limited to this, and the target current may be changed depending on the installation environment of the apparatus main body 10 or may be changed for each color. Moreover, the primary transfer voltage is used at 0.5 to 7.0 kV.

  Next, control of the secondary transfer voltage will be described with reference to FIG. Control of the secondary transfer voltage is similar to control of the primary transfer voltage. In general, control of the secondary transfer voltage includes constant voltage control and constant current control, but in the present embodiment, constant voltage control is used. A table of the secondary transfer current is stored in the secondary transfer voltage storage unit / calculation unit 31 f depending on the installation environment of the apparatus main body 10. In the secondary transfer device 45, current flows from the secondary transfer inner roller 45a to the intermediate transfer belt 44b and the secondary transfer outer roller 45b. ATVC control is performed to correct resistance change. The timing at which ATVC control is performed is performed after ATVC control of primary transfer shown in the flowchart of FIG.

  In the ATVC control, a signal is input from the CPU 31 to the ATVC control process unit 31 b to charge the photosensitive drum 51 in the same manner as in the image forming process. Next, as with the primary transfer voltage, a plurality of levels of voltages are applied to the secondary transfer outer roller 45b, and the current at that time is detected by the current detection sensor 76b. The secondary transfer voltage obtained by this calculation result is used as Vb and applied voltage at the time of secondary transfer. In the secondary transfer, since the secondary transfer is performed on the secondary transfer device 45 by sandwiching the sheet S, the impedance becomes higher by the amount of the sheet S than when ATVC control is performed, and the desired secondary transfer current is Vb. Can not flow. Therefore, in consideration of the rise in impedance when a certain sheet S is selected, the voltage Vp (the shared voltage of the sheet) necessary to flow the desired secondary transfer current is added to Vb obtained by ATVC control. Apply. That is, Vb + Vp is applied as a setting voltage for secondary transfer. The shared voltage of the sheet S is previously stored in a table according to the type of sheet S, basis weight, and installation environment of the apparatus main body 10, and is selected by the user selecting the sheet type.

  Next, the belt cleaning device 60 will be described in detail with reference to FIG. In general, the belt cleaning device 60 electrostatically collects and cleans the secondary transfer residual toner on the intermediate transfer belt 44b. The cleaned intermediate transfer belt 44b is repeatedly used in the image forming and imaging steps. The belt cleaning device 60 is disposed at an upstream device (first electrostatic cleaning means) 61 disposed on the upstream side in the rotational direction of the intermediate transfer belt 44 b and at different positions downstream of the upstream device 61. And a downstream device (second electrostatic cleaning means) 62.

  The upstream device 61 includes an inner roller 61a, a fur brush 61b, a recovery roller 61c, a cleaning blade 61d, a first cleaning power source 61e, a first voltage detection sensor 61f, and a first current detection sensor 61g See FIG. 2). The downstream device 62 includes an inner roller 62a, a fur brush 62b, a recovery roller 62c, a cleaning blade 62d, a second cleaning power source 62e, a second voltage detection sensor 62f, and a second current detection sensor 62g See FIG. 2). The upstream device 61 and the downstream device 62 have opposite polarities of the applied voltage, but the other configurations are the same.

  In the upstream device 61, the toner is transferred from the intermediate transfer belt 44b to the fur brush 61b by the negative bias applied to the collection roller 61c. Then, the toner of the fur brush 61b is transferred to the collection roller 61c, and is cleaned by the cleaning blade 61d installed on the collection roller 61c. From the intermediate transfer belt 44b, the toner that has not been cleaned by the fur brush 61b is a tribo of the same polarity as the developing toner, in which the toner charged to the minus side slips through. The control unit 30 applies a first cleaning voltage so that the first cleaning power source 61 e flows a first cleaning current (for example, −55 μA) to the upstream device 61 in the cleaning mode. That is, the control unit 30 detects the current value flowing into the collection roller 61c at any time by the current detection sensor 61g, and outputs the first cleaning power source 61e so that the detected current value matches the first cleaning current. Perform constant current control to control voltage. In the present embodiment, the first cleaning current is −55 μA, but it is not limited to this. Thus, the upstream device 61 electrostatically cleans the intermediate transfer belt 44b by applying the first cleaning voltage.

  Subsequently, in the downstream side device 62, the fur brush 62b is positively biased and the minus toner is cleaned so that both the plus toner and the minus toner of the intermediate transfer belt 44b can be cleaned. In the cleaning mode, the control unit 30 performs the second cleaning with the opposite polarity to the first cleaning voltage so that the second cleaning power supply 62e supplies the second cleaning current (for example, +55 μA) to the downstream device 62. Apply a voltage. That is, the cleaning voltage storage unit / calculation unit 31e of the control unit 30 detects the current value flowing into the collection roller 62c at any time by the current detection sensor 62g, and matches the detected current value with the second cleaning current. A constant current control is performed to control the output voltage from the second cleaning power source 62e. In the present embodiment, the second cleaning current is +55 μA, but it is not limited to this. Thus, the downstream device 62 electrostatically cleans the intermediate transfer belt 44b by applying the second cleaning voltage.

  The cleaning voltage storage unit / calculation unit 31e of the control unit 30 calculates the first cleaning voltage and the second cleaning voltage. Based on the calculation result, output signals are sent to the cleaning power sources 61e and 62e, and cleaning voltages are applied during image formation. Since the belt cleaning device 60 may always receive toner while the intermediate transfer belt 44b is rotating, the cleaning voltage is applied in synchronization with the rotation and stop of the intermediate transfer belt 44b.

The fur brush 61 b and the fur brush 62 b have a yarn resistance value of 3.0 × 10 ^{5 to} 1.0 × 10 ¹³ (Ω / cm). And it is formed by flocking a carbon dispersion type nylon fiber, acrylic fiber or polyester fiber of 2-15 denier of fiber thickness on the metal roller at the ratio of its flocked density 50,000 to 500,000 / inch ² . The respective fur brushes 61b and 62b are disposed in sliding contact with the intermediate transfer belt 44b while maintaining an intrusion amount of about 1.0 to 2.0 mm, and the conveyance speed of the intermediate transfer belt 44b is 20 to 20 by a drive motor (not shown). It is formed to rotate at a speed of 80%. The collection rollers 61c and 62c are disposed with an infiltration amount of 1.5 to 2.5 mm with respect to the fur brushes 61b and 62b, and are arranged to be rotated at the same speed as the fur brushes 61b and 62b. . The cleaning blades 61d and 62d are plate-like rubbers such as urethane, and have a thickness of 1.6 to 2.2 mm and an IRHD hardness of 70 to 78 ° (23 ° C., 50% RH). It is arrange | positioned keeping 0.5-2.0 mm.

  In the above configuration, the replacement time of the intermediate transfer belt 44b will be described in detail. The intermediate transfer belt 44 b is applied with the respective primary transfer voltages, the secondary transfer voltages, and the respective cleaning voltages from the energizing unit. It is known that the resistance value (volume resistivity) is increased by this energization. The mechanism of the rise in resistance is considered to be a mechanism in which the conductor in the elastic layer moves out, and a mechanism in which the dielectric is polarized.

For example, it is assumed that the initial volume resistivity of the intermediate transfer belt 44b starts long-term use at about 1.0 × 10 ¹¹ Ω · cm (23 ° C., 50% RH). Changes in volume resistivity of the intermediate transfer belt 44b in this case are shown in FIG. As shown in FIG. 5, when about 500,000 sheets of image are formed on A4 size sheet S, the resistance is up to 2.4 × 10 ¹² [Ω · cm] (23 ° C., 50% RH) To rise. At this time, the rise in resistance becomes uneven and resistance unevenness can be made, so that the primary transfer current becomes uneven, thereby becoming primary transfer unevenness, becoming an image unevenness of several mm pitch on the image, and causing an image defect. There is a risk of causing it. In the image forming apparatus 1 according to the present embodiment, when the volume resistivity exceeds about 8.0 × 10 ¹¹ [Ω · cm], the possibility of the occurrence of the image defect increases. It has been found.

  Next, among the currents flowing to the intermediate transfer belt 44b, it is considered which current is the cause of the increase in resistance. The increase in resistance due to the current flowing from the inside to the outside of the intermediate transfer belt 44b is canceled by the current flowing from the outside to the inside of the intermediate transfer belt 44b. The bias applied to the intermediate transfer belt 44b is supplied from the respective power supplies of the primary transfer power supply 75, the secondary transfer power supply 76, and the cleaning power supplies 61e and 62e. Among them, from the primary transfer power supply 75, a total current of 220 μA flows from the inside to the outside of the intermediate transfer belt 44b because 55 μA for each color, for a total of four colors. A current of 70 μA flows from the outer side of the intermediate transfer belt 44b to the inner side from the secondary transfer outer roller 45b. The cleaning power supplies 61e and 62e of the belt cleaning device 60 cancel each other because they have the same current value and opposite polarity. That is, since the secondary transfer current is 70 μA and the primary transfer current is 150 μA higher than the primary transfer current 220 μA, the resistance increase of the intermediate transfer belt 44 b occurs due to the primary transfer current. However, in the black and white mode, the primary transfer current of colors other than black is turned off, and 55 μA of black alone is supplied. Since the secondary transfer current is still 70 μA, the secondary transfer current is higher by 15 μA, and the rise in resistance is alleviated although slightly as compared with the full color mode.

  On the other hand, it was found that as the change in volume resistivity increases, the larger the number of image formation per day, the larger the increase in resistance. That is, it has been found that when the number of image formation per day is small, the above-described image defects do not occur even after long-term use. The mechanism is considered to be that the electric dipole polarized by energization by image formation is subjected to dielectric relaxation at the time of stopping to return to the original resistance value. Therefore, when the number of image formation per day is small, the volume resistivity of the intermediate transfer belt 44b is relatively maintained while repeating the resistance increase and the resistance decrease.

  Therefore, if it is possible to predict the change in volume resistivity of the intermediate transfer belt 44b, it is not necessary to replace the intermediate transfer belt 44b with a fixed uniform number of image formations, and unnecessary replacement of the intermediate transfer belt 44b is eliminated. The average life of the belt 44b can be extended. In order to predict changes in volume resistivity of the intermediate transfer belt 44b, first, attention is paid to changes in long-term use of each voltage value of the primary transfer voltage, the secondary transfer voltage, and the cleaning voltage. The long-term change in the voltage value of the voltage output from each power supply includes the resistance change of not only the intermediate transfer belt 44b but also the primary transfer roller 47, the secondary transfer outer roller 45b, and the fur brushes 61b and 62b. . For this reason, it is difficult to predict the change in volume resistivity of the intermediate transfer belt 44b only by the long-term use change of the voltage value of the voltage output from the single power supply. Therefore, we considered calculating and predicting from a plurality of bias outputs.

  For example, it is assumed that the primary transfer current 55 μA applied by the yellow primary transfer roller 47 y charges the intermediate transfer belt 44 b and attenuates before the primary transfer current is applied by the primary transfer roller 47 m of the next magenta station. . In this case, if the impedance is the same even at the next magenta station, the voltage required to flow the primary transfer current of 55 μA in the same current-carrying region does not differ greatly from the voltage applied to the yellow primary transfer roller 47y. However, when the volume resistivity of the intermediate transfer belt 44b increases, the charge does not attenuate at a distance of 250 mm from the primary transfer roller 47y to the primary transfer roller 47m, and the impedance at the magenta primary transfer roller 47m in the same conduction region Will change. For this reason, the voltage required to cause the primary transfer current 55 μA to flow to the magenta primary transfer roller 47 m is higher than that of the yellow primary transfer roller 47 y. That is, focusing on the primary transfer voltage, as the volume resistivity of the intermediate transfer belt 44b increases, the voltage necessary for the primary transfer in the same energized region increases as it goes to the downstream station. This is referred to as charge-up because it is a voltage increase due to the charge of the intermediate transfer belt 44b not decaying.

  FIG. 6A shows the change in the primary transfer voltage of the image forming apparatus 1 of the present embodiment for each color. As described above, it is assumed that the difference between the respective colors is correlated with the impedance due to the change in volume resistivity of the intermediate transfer belt 44b. Therefore, based on the result shown in FIG. 6A, for example, the first primary transfer voltage of yellow is subtracted from the second primary transfer voltage of black, and the absolute value of the obtained voltage difference is shown in FIG. shown in b). In the present specification, the voltage difference indicates an absolute value (absolute voltage difference) of the voltage difference. From the voltage difference between the primary transfer voltages of black and yellow shown in FIG. 6B and the change of the image during long-term use, the image failure is caused by the voltage of the primary transfer voltage of black and yellow. It turned out that it was when the difference became 2000 V or more. Therefore, in consideration of a margin such as variation in occurrence, when the voltage becomes 1800 V, which is 10% smaller than 2000 V, an exchange alarm is displayed on the display unit 70a of the operation unit 70 as information on the exchange of the intermediate transfer belt 44b.

  The display procedure of the replacement alarm will be described in detail along the flowcharts shown in FIGS. 7 and 8. The timing for performing the ATVC control is when the predetermined fixing temperature is reached before the start of image formation (so-called, during pre-rotation) after power on and every time when the number of image formation reaches the predetermined number after the start of image formation. ing. With regard to ATVC control when a predetermined fixing temperature is reached after power on and before the start of image formation, as shown in FIG. 7, it is determined whether a replacement alarm is displayed each time ATVC control is performed. When ATVC control is performed (step S20), the primary transfer voltage storage unit / arithmetic unit 31d calculates the absolute value (absolute voltage difference) of the voltage difference between the primary transfer voltages of black and yellow based on the result. The CPU 31 determines whether the voltage difference between the primary transfer voltages of black and yellow is equal to or greater than 1800 V (step S21). If the CPU 31 determines that the voltage difference between the primary transfer voltages of black and yellow is equal to or greater than 1800 V, it displays an exchange alarm on the display unit 70a (step S22). When the CPU 31 determines that the voltage difference between the primary transfer voltages of black and yellow is not 1800 V or more, the CPU 31 prepares for the next ATVC control without displaying the replacement alarm on the display unit 70a (step S23).

  As shown in FIG. 8, for ATVC control every time when the number of sheets for image formation reaches a predetermined number of sheets after the start of image formation, it is determined whether a replacement alarm is to be displayed after inter-sheet ATVC control. The inter-sheet ATVC control performs control during continuous image formation. When image formation is started (step S30), the CPU 31 determines whether the number of image formation is M or more (step S31). As described above, M = 28 × N + 1, (N = 1, 2, 3,...). If the number of formed images is not M or more, the image formation is continued (step S30). If the number of sheets for image formation is M or more, voltage correction is performed between the sheets (step S32). That is, in the present embodiment, the current is detected between the sheets every 28 sheets as the predetermined number of sheets, and when the current value changes, the predetermined voltage ΔV is applied and applied as the primary transfer voltage.

  Also for the voltage after the inter-sheet ATVC control, the primary transfer voltage storage unit / calculation unit 31 d calculates the voltage difference between the primary transfer voltages of black and yellow. The CPU 31 determines whether the voltage difference between the primary transfer voltages of black and yellow is equal to or greater than 1800 V (step S33). If the CPU 31 determines that the voltage difference between the primary transfer voltages of black and yellow is equal to or greater than 1800 V, it displays a replacement alarm on the display unit 70a (step S34). When the CPU 31 determines that the voltage difference between the primary transfer voltages of black and yellow is not 1800 V or more, the CPU 31 prepares for the next ATVC control without displaying the replacement alarm on the display unit 70a (step S35).

  As shown in FIG. 7 and FIG. 8, after ATVC control, the control unit 30 is an absolute voltage difference which is an absolute value of a voltage difference between the voltage value of the black primary transfer voltage and the voltage value of the yellow primary transfer voltage. When the voltage V is equal to or greater than 1800 V, information on the replacement of the intermediate transfer belt 44b is output. That is, based on the relationship between the first primary transfer voltage and the second primary transfer voltage set in the ATVC control, the control unit 30 outputs a replacement alarm of the intermediate transfer belt 44b to display the replacement alarm on the display unit 70a. Display on Further, in the present embodiment, the control unit 30 obtains voltage values of two primary transfer voltages to calculate a voltage difference, and uses the result as a value related to the volume resistivity of the intermediate transfer belt 44 b.

  FIG. 9 is a graph showing the voltage difference between the primary transfer voltages of black and yellow for a week. The horizontal axis is the time of day. Each day, the use starts from the morning, and as the operation time increases, the voltage difference increases. The blanks formed during each day are non-use at night and indicate that when the use is finished and the device shuts down, the voltage difference will drop in the morning of the next day. In addition, on the sixth and seventh days, it is assumed that a two-day stop on Saturday and Sunday is assumed, and it can be seen that when the image forming operation is stopped for two days, the voltage value drops more. That is, the above-described increase in resistance and the decrease in resistance due to dielectric relaxation were supported.

  Although the timing of the ATVC control is set to the timing of the pre-rotation and the sheet interval for each predetermined number of sheets as described above, the timing is not limited to such timing. Further, depending on the use conditions of the user, the exchange alarm may not be displayed on the display unit 70a without reaching the threshold of 1800 V or more. That is, depending on the method of use, there is a possibility that the image failure due to the uneven resistance of the intermediate transfer belt 44b does not occur. However, the life of the intermediate transfer belt 44b is not determined only by the increase in volume resistivity, and in the case where no image failure occurs, another reason for determining the life arises and the life is reached.

  Therefore, in the present embodiment, the image formation counter storage unit / calculation unit 31g (see FIG. 2) of the control unit 30 stores the number of image formations. The image formation counter storage unit / calculation unit 31g is used as a counter for acquiring the number of image formations after the start of use of the intermediate transfer belt 44b. The start of use of the intermediate transfer belt 44b means the time of purchase of the image forming apparatus or when the intermediate transfer belt 44b is replaced with a new one. Then, the control unit 30 determines whether the number of image formations obtained by the counter has reached a predetermined number, for example, three million even if the calculation result of the ATVC control does not reach 1800 V or more. When the number of image formations obtained by the counter reaches 3 million, the control unit 30 causes the display unit 70a to display an alarm for replacing the intermediate transfer belt 44b. As a result, it is possible to prevent the intermediate transfer belt 44b from continuing to be used even if it reaches the end of life for reasons other than the increase in volume resistivity.

  As described above, according to the image forming apparatus 1 of the present embodiment, when the voltage difference between the primary transfer voltage of black and the primary transfer voltage of yellow is 1800 V or more, the control unit 30 The replacement alarm is displayed on the display unit 70a. Therefore, it is possible to prevent image defects caused by the uneven resistance of the intermediate transfer belt 44b in advance, and to separately determine the original replacement timing slightly before the life of the intermediate transfer belt 44b. The average replacement time of 44b can be extended.

  Further, according to the image forming apparatus 1 of the present embodiment, the two primary transfer voltages for calculating the voltage difference are the primary transfer voltages of black and yellow. The black photosensitive drums 51k and the yellow photosensitive drums 51y are two photosensitive drums 51 disposed among the plurality of photosensitive drums 51 most distantly along the rotational direction. Therefore, among the four primary transfer voltages, the voltage difference between black and yellow is the largest, so that the detection error can be reduced.

Second Embodiment
Next, a second embodiment of the present invention will be described in detail with reference to FIG. The present embodiment differs from the first embodiment in that the image formation is performed in the black and white mode. However, since the other configuration is the same as that of the first embodiment, the reference numerals are the same, and the detailed description will be omitted.

  First, the black and white mode (monochrome mode) will be described. In the black and white mode, image formation of yellow, magenta, and cyan is not performed, and image formation is performed using only black. At this time, since the primary transfer is stopped except for black, the primary transfer current does not flow, and the increase in the resistance of the intermediate transfer belt 44 b is smaller than that in the full color. However, since only the primary transfer current of black flows, the increase in the resistance of the primary transfer roller 47k of black proceeds.

That is, the application voltage of black is VBk, the application voltage of yellow is Vy, and the application voltage by the charge-up of the intermediate transfer belt 44b is VITB. Assuming that the voltage due to the resistance of the black primary transfer roller 47k to increase more than the yellow primary transfer roller 47y due to the current in the black and white mode is V1, the voltage difference between black and yellow is calculated as It will be.
VBk-Vy = VITB + V1 ... (Equation 1)

Calculate V1 to determine VITB. When the increase in the resistance of the primary transfer roller 47 k was examined, the resistance of the A4 size sheet S increased by 1000 V with one million sheets. Therefore, the black-and-white mode is calculated by predicting that the voltage applied to the primary transfer roller 47k by 0.001 V will increase when an image is formed in A4 conversion. In order to calculate the number of times of image formation, a counter CNTk of the number of times of image formation in monochrome mode is prepared in the image formation counter storage unit / calculation unit 31g (see FIG. 2). In this case, the voltage V1 applied to the primary transfer roller 47k is expressed by Formula 2.
V1 = 0.001 × (CNTk) (Equation 2)
However, (CNTk) is the number of image formations in the black and white mode.

From Equation 1 and Equation 2, VITB is obtained by Equation 3 below. As in the first embodiment, the magnitude of this VITB is determined with a threshold of 1800 V to issue an alarm for replacing the intermediate transfer belt 44b. That is, when executing the black and white mode, the control unit 30 corrects the absolute voltage difference between the primary transfer voltages of black and yellow by the number of image formations using the black primary transfer roller 47k. That is, the control unit 30 sets the intermediate transfer belt 44b replacement alarm based on the first primary transfer voltage and the second primary transfer voltage set in the ATVC control, and the value regarding the number of sheets formed in the black and white mode. Output
VITB = VBk−Vy−0.001 × (CNTk) (Equation 3)

  The display procedure of the replacement alarm will be described in detail along the flowchart shown in FIG. Here, the process of reading and calculating the number of image formations in the black and white mode is added to the flowchart of the first embodiment (see FIG. 7). The timing at which ATVC control is performed is the same as in the first embodiment. When ATVC control is performed (step S40), the primary transfer voltage storage unit / arithmetic unit 31d calculates a voltage difference between the primary transfer voltages of black and yellow based on the result. Furthermore, the CPU 31 reads the counter CNTk of the number of image formations in the black and white mode from the image formation counter storage unit / calculation unit 31g, and calculates VITB (step S41). The CPU 31 determines whether VITB is equal to or greater than 1800 V (step S42). If the CPU 31 determines that the VITB is equal to or greater than 1800 V, it displays a replacement alarm on the display unit 70a (step S43). If it is determined that the VITB is not at least 1800 V, the exchange alarm is not displayed on the display unit 70a, and the next ATVC control is prepared (step S44). This makes it possible to correct the increase in the resistance of the black primary transfer roller 47k in the black and white mode, and to determine the replacement timing of the intermediate transfer belt 44b more accurately.

  As described above, according to the image forming apparatus 1 of the present embodiment, the control unit 30 displays an intermediate transfer belt 44 b replacement alarm on the display unit 70 a when the VITB is equal to or greater than 1800V. Therefore, it is possible to prevent image defects caused by the uneven resistance of the intermediate transfer belt 44b in advance, and to separately determine the original replacement timing slightly before the life of the intermediate transfer belt 44b. The average replacement time of 44b can be extended.

  Further, according to the image forming apparatus 1 of the present embodiment, the image forming apparatus 1 is executed in the black and white mode. Therefore, even in the single color mode as well as in the full color mode, the average replacement time of the intermediate transfer belt 44b can be determined by individually determining the original replacement time that is slightly before the life of the intermediate transfer belt 44b. It can be extended.

Third Embodiment
Next, a third embodiment of the present invention will be described in detail with reference to FIGS. 11 and 12. The present embodiment differs from the first embodiment in that the voltage difference between the primary transfer voltages of cyan and yellow is used. However, since the other configuration is the same as that of the first embodiment, the reference numerals are the same, and the detailed description will be omitted.

  In this embodiment, the voltage difference between the primary transfer voltages of yellow and cyan is used to avoid the influence of the increase in the resistance of only the black primary transfer roller 47k due to the black and white mode. Based on the temporal change of the primary transfer voltage shown in FIG. 6A, the voltage difference between the black and yellow primary transfer voltages and the voltage difference between the cyan and yellow primary transfer voltages are calculated, and the results are shown in FIG. Show. Although the chargeup is smaller at the primary transfer voltage of cyan than the primary transfer voltage of black, the occurrence of an image defect can be determined. As a result of further investigations and finding the threshold value for the occurrence of the image defect in the voltage difference between the primary transfer voltages of cyan and yellow, it was found that the optimum value is 1600 V. In this case, the photosensitive drum 51c of cyan corresponds to the second image carrier, and the primary transfer power source 75c of cyan corresponds to the second primary transfer power source.

  The display procedure of the replacement alarm will be described in detail along the flowchart shown in FIG. The general flow is the same as the flow chart shown in FIG. 7 of the first embodiment. That is, when ATVC control is performed (step S50), the primary transfer voltage storage unit / arithmetic unit 31d calculates the voltage difference between the primary transfer voltages of cyan and yellow based on the result. The CPU 31 determines whether the voltage difference between the primary transfer voltages of cyan and yellow is 1600 V or more (step S51). If the CPU 31 determines that the voltage difference between the primary transfer voltages of cyan and yellow is 1600 V or more, it displays a replacement alarm on the display unit 70a (step S52). When the CPU 31 determines that the voltage difference between the primary transfer voltages of cyan and yellow is not 1600 V or more, the CPU 31 prepares for the next ATVC control without displaying the replacement alarm on the display unit 70a (step S53). Also in the present embodiment, it is possible to accurately determine the replacement time of the intermediate transfer belt 44b.

  As described above, according to the image forming apparatus 1 of the present embodiment, when the voltage difference between the cyan and yellow primary transfer voltages is 1600 V or more, the control unit 30 issues an alarm for replacing the intermediate transfer belt 44 b. Display on the display unit 70a. Therefore, for example, even when the increase in resistance of the black primary transfer roller 47k is larger than that of the other primary transfer rollers in the primary transfer roller 47, it is possible to accurately determine the replacement time of the intermediate transfer belt 44b. . Therefore, it is possible to prevent image defects caused by the uneven resistance of the intermediate transfer belt 44b in advance, and to separately determine the original replacement timing slightly before the life of the intermediate transfer belt 44b. The average replacement time of 44b can be extended.

Fourth Embodiment
Next, a fourth embodiment of the present invention will be described in detail with reference to FIG. 13 and FIG. The present embodiment differs from the first embodiment in that the voltage difference of the cleaning voltage of the belt cleaning device 60 is used. However, since the other configuration is the same as that of the first embodiment, the reference numerals are the same, and the detailed description will be omitted.

  In the first embodiment, the replacement time of the intermediate transfer belt 44b is predicted from the voltage value applied to the primary transfer roller 47, but in the present embodiment, it is predicted by the cleaning voltage of the belt cleaning device 60. That is, based on the relationship between the first cleaning voltage and the second cleaning voltage applied in the cleaning mode, the control unit 30 outputs an alarm for replacing the intermediate transfer belt 44b and displays it on the display unit 70a. In the present embodiment, the first cleaning power source 61e is a first energizing unit, and the second cleaning power source 62e is a second energizing unit.

  The belt cleaning device 60 is under constant current control. That is, the control unit 30 detects current values flowing into the collection rollers 61c and 62c as needed by the current detection sensors 61g and 62g, and makes the detected current values coincide with the respective cleaning currents from the cleaning power supplies 61e and 62e. Control the output voltage of At this time, at the timing when the area of the intermediate transfer belt 44b to which the first cleaning voltage is applied from the upstream fur brush 61b passes while contacting the downstream fur brush 62b, the second downstream fur brush 62b Control the cleaning voltage of the The impedance of the intermediate transfer belt 44b and the fur brushes 61b and 62b (see FIG. 4) is obtained by reading out and acquiring the applied voltage value at the time of constant current control during image formation from the cleaning voltage storage / calculation unit 31e after image formation is completed. Change can be obtained. In the present embodiment, the belt cleaning device 60 is controlled by constant current control. However, the present invention is not limited to this and constant voltage control may be used.

  FIG. 13A shows temporal changes in the first cleaning voltage applied to the upstream collecting roller 61c under constant current control and the second cleaning voltage applied to the downstream collecting roller 62c. It is. From this result, it is difficult to understand the resistance change of the intermediate transfer belt 44b. Therefore, as shown in FIG. 13B, the first cleaning voltage applied to the collection roller 62c on the upstream side is subtracted from the second cleaning voltage applied to the collection roller 61c on the downstream side, and the absolute difference in voltage is obtained. The value was calculated. By calculating the voltage difference in this manner, the resistance variation of the fur brushes 61b and 62b is removed, and the change in volume resistivity of the intermediate transfer belt 44b can be predicted. Here, since the image defect occurs when the calculation result of subtracting the first cleaning voltage from the second cleaning voltage is smaller than 4800 V, when it becomes 4900 V or less, the display unit of the operation unit 70 An intermediate transfer belt 44b replacement alarm is displayed on 70a.

  The display procedure of the replacement alarm will be described in detail along the flowchart shown in FIG. In the present embodiment, at the time of rotation after the image formation is completed, the cleaning voltage is obtained to calculate the voltage difference. When the image formation is completed (step S60), the cleaning voltage output at the time of the last image formation is read out and acquired from the cleaning voltage storage unit / calculation unit 31e (step S61). The cleaning voltage storage unit / calculation unit 31e calculates a voltage difference between the downstream second cleaning voltage and the upstream first cleaning voltage (step S62). The CPU 31 determines whether the voltage difference between the downstream second cleaning voltage and the upstream first cleaning voltage is 4900 V or less (step S63). When the CPU 31 determines that the voltage difference between the downstream second cleaning voltage and the upstream first cleaning voltage is 4900 V or less, the CPU 31 displays a replacement alarm on the display unit 70a (step S64). When the CPU 31 determines that the voltage difference between the downstream second cleaning voltage and the upstream first cleaning voltage is not 4900 V or less, the next image is displayed without displaying the replacement alarm on the display unit 70a. Prepare for the end of formation (step S65). By using the image forming apparatus 1 having such a configuration, it is possible to accurately determine the replacement time of the intermediate transfer belt 44b.

  As described above, according to the image forming apparatus 1 of the present embodiment, the control unit 30 sets the voltage difference between the downstream second cleaning voltage and the upstream first cleaning voltage to a predetermined voltage, for example, 4900 V or less In this case, the intermediate transfer belt 44b replacement alarm is displayed on the display unit 70a. Therefore, it is possible to prevent image defects caused by the uneven resistance of the intermediate transfer belt 44b in advance, and to separately determine the original replacement timing slightly before the life of the intermediate transfer belt 44b. The average replacement time of 44b can be extended.

Fifth Embodiment
Next, a fifth embodiment of the present invention will be described in detail with reference to FIG. 15 and FIG. The present embodiment differs from the first embodiment in that the replacement time of the intermediate transfer belt 44b is determined based on the average number of image formations per day after long-term use. However, since the other configuration is the same as that of the first embodiment, the reference numerals are the same, and the detailed description will be omitted. Further, in the present embodiment, the image formation is performed in the full color mode, and the target current in each of the primary transfer portions 48 is 55 μA.

  In the present embodiment, the increase in the resistance of the intermediate transfer belt 44b, that is, the increase in volume resistivity is predicted from the average number of image formation per day after long-term use, and the replacement time of the intermediate transfer belt 44b is predicted. The number of image formations is converted to A4 size. That is, when the size in the moving direction of the sheet S is B4 size (364 mm) or less, it is counted as one sheet, and when it exceeds 364 mm longer than B4 size, it is counted as two sheets. FIG. 15 (a) shows the primary of yellow and black for the case of image formation of 30,000 sheets a day for long-term use and the case of image formation of 10,000 sheets a day for long-term use It is a graph which shows the voltage difference of a transfer voltage. As described in the first embodiment, when the voltage difference between the primary transfer voltages of yellow and black reaches 2000 V, an image failure occurs. Here, in the case of long-term use (for example, 20 days) in the image formation of 10,000 sheets a day, the voltage difference is about 1500 V at the maximum, so that the image defect due to the uneven resistance of the intermediate transfer belt 44b does not occur.

  FIG. 15B shows the relationship between the number of images formed on one day, the voltage difference between the primary transfer voltages of black and yellow, and the presence or absence of an image defect when the number of images formed on one day is changed and used for a long time Indicates As can be seen from FIG. 15 (b), it is possible to predict that image defects will occur if 15,000 or more images are formed per day and used for a long time. On the other hand, although not shown in FIG. 15B, in the case of relatively short-term use where the number of image formation from the start of use of the intermediate transfer belt 44b is 300,000 or less, 15,000 or more per day. Even when image formation is performed, no image defect usually occurs. Therefore, in the present embodiment, after the integrated value of the number of image formations from the start of use of the intermediate transfer belt 44b exceeds 300,000, the control unit 30 controls the number of image formations per day from the start of use to 15,000. If there are more than one, issue a replacement alarm. That is, the first condition is that the integrated value of the number of image formations after the start of use of the intermediate transfer belt 44b exceeds 300,000 sheets (first predetermined value). The second value is that the value per day obtained by dividing the integrated value of the number of formed images after the start of use of the intermediate transfer belt 44b by the number of days elapsed after the start of use is 15000 or more (more than the second predetermined value). It is a condition. Then, when the first condition and the second condition are satisfied, the control unit 30 sends an alarm for replacing the intermediate transfer belt 44b and displays it on the display unit 70a. Here, 300,000 sheets correspond to the first predetermined value, and 15,000 sheets correspond to the second predetermined value, but it goes without saying that the present invention is not limited thereto.

  Here, the amount of increase in the volume resistivity of the intermediate transfer belt 44b depends on the number of images formed and the transfer current to the intermediate transfer belt 44b. That is, in the present embodiment, since the target current in each primary transfer portion 48 is fixed at 55 μA, the amount of increase in volume resistivity is dependent on the number of image formations, but the number of image formations is the same. Also, the amount of increase in volume resistivity changes as the transfer current changes. For example, in the present embodiment, the target current is 55 μA, and the number of image formations to be integrated in one image formation is one sheet (first value Pa), but when the transfer current is different, the image formation is integrated. It is necessary to convert the number of sheets based on (transfer current / 55 μA). Specifically, for example, when the transfer current is set from 55 μA (first current value) to 110 μA (second current value) which is twice, the increase amount of the volume resistivity is approximately doubled. Therefore, the number of image formations to be integrated in one image formation is converted to two (second value Pb = 110/55). The first predetermined value 300,000 sheets and the second predetermined value 15000 sheets are used as they are. That is, when the current value supplied to the intermediate transfer belt 44b from each primary transfer power source 75 is 55 μA, the control unit 30 integrates the number of sheets for image formation integrated in one image formation as one sheet. In addition, when the absolute value of the current value is 110 μA, which is larger than 55 μA, the control unit 30 sets two sheets larger than one in one image formation even if the actual number of image formation is one. Accumulate.

  The display procedure of the replacement alarm will be described in detail based on the flowchart shown in FIG. Storage and calculation of the number of image formations are performed by the image formation counter storage unit / calculation unit (counter) 31g (see FIG. 2) of the control unit 30. In the present embodiment, the image formation counter storage unit / calculation unit 31g also functions as a counter that counts the number of image formation sheets as a value related to the amount of current. The storage and calculation of the application time to which the primary transfer voltage is applied and the stop time not to be applied are performed by the timer storage unit / operation unit 31h (see FIG. 2) of the control unit 30. When the image formation is completed (step S70), the number of times of image formation (integrated value) P1 from the start of use of the intermediate transfer belt 44b is acquired from the image formation counter storage unit / calculation unit 31g (step S71). When the image formation counter storage unit / calculation unit 31g integrates the image formation number P1 after the start of use, the image formation number converted based on (transfer current / 55 μA) for each image formation Is accumulated. Then, the application time and stop time of the primary transfer voltage from the start of use of the intermediate transfer belt 44b are obtained from the timer storage unit / calculation unit 31h (step S72). The CPU 31 adds the acquired application time and stop time to calculate the number of days elapsed from the start of use of the intermediate transfer belt 44b (step S73).

  The CPU 31 divides the number of formed images P1 after the start of use of the intermediate transfer belt 44b by the number of days elapsed after the start of use to calculate the number of formed images P2 per day (step S74). The CPU 31 determines whether the number P1 of formed images after the start of use of the intermediate transfer belt 44b exceeds 300,000 (step S75). If the CPU 31 determines that the number P1 of image formation after the start of use of the intermediate transfer belt 44b exceeds 300,000, whether the number P2 of image formation per day calculated in step S74 is 15,000 or more It judges (step S76).

  If the CPU 31 determines that the number of image formations P2 per day is 15000 or more, it displays a replacement alarm on the display unit 70a (step S77). If the CPU 31 determines that the number of times of image formation P2 per day is not 15000 or more, the exchange alarm is not displayed on the display unit 70a (step S78) to prepare for the end of the next image formation. Similarly, when the CPU 31 determines that the number P1 of formed images after the start of use of the intermediate transfer belt 44b does not exceed 300,000, the replacement alarm is not displayed on the display unit 70a (step S78). Prepare for the end of image formation.

  Here, also in the present embodiment, the total image formation from the initial use of the intermediate transfer belt 44b to the output time of the exchange information for prompting replacement according to the daily usage amount (the number of images formed and the electrification amount) of the image forming apparatus 1 The number has been changed. That is, when images are formed continuously under the first operation condition where the number of image formation P2 formed on one day is 15,000 sheets (predetermined number) or more, image formation up to the time of outputting the exchange information of the intermediate transfer belt 44b The number is 3001 (first number). On the other hand, when images are formed continuously on the second day under the second operating condition that the number of image formation formed per day is less than 15000, the exchange information of the intermediate transfer belt 44b is not output (step S78). The number of times of image formation until time is a second number which is larger than the first number.

  As described above, according to the image forming apparatus 1 of the present embodiment, the control unit 30 causes the number of image formation P1 after the start of use to reach 300,000, and the number of image formation P2 per day is 15,000 or more. In this case, the intermediate transfer belt 44b replacement alarm is displayed on the display unit 70a. By using the image forming apparatus 1 having such a configuration, it is possible to accurately determine the replacement time of the intermediate transfer belt 44b. Therefore, it is possible to prevent image defects caused by the uneven resistance of the intermediate transfer belt 44b in advance, and to separately determine the original replacement timing slightly before the life of the intermediate transfer belt 44b. The average replacement time of 44b can be extended.

Sixth Embodiment
Next, a sixth embodiment of the present invention will be described in detail with reference to FIG. The present embodiment differs from the fifth embodiment in that the image formation is performed in the black and white mode. However, since the other configuration is the same as that of the fifth embodiment, the reference numerals are the same and the detailed description will be omitted.

  The display procedure of the replacement alarm will be described in detail based on the flowchart shown in FIG. First, the image formation ends (step S80). All image formation sheet numbers (integrated value) P1 from the start of use of the intermediate transfer belt 44b and image formation sheet numbers (integrated value) P3 in the monochrome mode from the use start are acquired from the image formation counter storage unit / calculation unit 31g (Step S81). Here, in the black-and-white mode, as described above, a current of a magnitude that allows the resistance rise of the intermediate transfer belt 44b to be slightly relaxed flows compared to the full-color mode. Therefore, assuming that the volume resistivity of the intermediate transfer belt 44b hardly changes even when an image is formed in the black and white mode, the number P3 of image formations in the black and white mode is excluded from all the numbers P1 of image formation. That is, the value relating to the amount of energization in this case, that is, the number P4 of image formations means the number P4 of images formed in the full color mode excluding the number P3 of images formed in the black and white mode from the number P1 of all image formations. Therefore, the CPU 31 subtracts the number of image formations P3 in the monochrome mode from all the number of image formations P1 from the start of use (step S82). Since the procedure of subsequent step S72-step S78 is the same as that of 5th Embodiment, it carries out the code | symbol same and abbreviate | omits detailed description.

  As described above, according to the image forming apparatus 1 of the present embodiment, the control unit 30 calculates an image in the full color mode calculated by subtracting the number of image formation P3 in the black and white mode from the total number of image formation P1 from the start of use. The formation number P4 is used. Then, after the image formation number P4 in the full color mode after the start of use reaches 300,000, when the image formation number P2 per day is 15000 or more, the replacement alarm of the intermediate transfer belt 44b is displayed on the display unit 70a. indicate. By using the image forming apparatus 1 having such a configuration, it is possible to accurately determine the replacement timing of the intermediate transfer belt 44b even when the black and white mode is used.

Seventh Embodiment
Next, a seventh embodiment of the present invention will be described in detail with reference to FIG. The present embodiment is different from the fifth embodiment in that the time to replace the intermediate transfer belt 44 b is determined based on the operation rate of the primary transfer power supply 75. The operation rate here is a rate obtained by dividing the integrated value of the application time of the primary transfer voltage after the start of use of the intermediate transfer belt 44b by the elapsed time after the start of use. The other configuration is the same as that of the fifth embodiment, so the reference numerals are the same and detailed description will be omitted. Further, in the present embodiment, the image formation is performed in the full color mode, and the target current in each of the primary transfer portions 48 is 55 μA.

  In the present embodiment, the average number of image formation per day after long-term use according to the fifth embodiment is converted into the operation rate of the primary transfer power supply 75. In the image forming apparatus 1 of the present embodiment, for example, when it is possible to form an image of 100 sheets per minute, it takes 150 minutes to output 15000 sheets. At this time, the ratio of the application time of the primary transfer voltage is 150 minutes / 24 hours = about 10%. Therefore, when the operation rate R1 of the primary transfer power source 75 from the start of use of the intermediate transfer belt 44b is 10% or more (a second predetermined value or more), image defects due to uneven resistance of the intermediate transfer belt 44b occur. Make a replacement alarm as a thing. In addition, 300,000 sheets, which is the minimum number of sheets in which the possibility of image defects in the fifth embodiment appears, is 50 hours (first predetermined value) when converted to the application time of the primary transfer voltage. Although the 50 hours here correspond to the first predetermined value and 10% to the second predetermined value, it is of course that the present invention is not limited thereto. Further, in the present embodiment, it is determined whether or not the operation rate R1 of the primary transfer power source 75 from the start of use of the intermediate transfer belt 44b is 10% or more. For example, the application time of the primary transfer voltage from the start of use is divided by the number of days elapsed after the start of use to calculate the application time of the primary transfer voltage per day, and it is determined whether this is 150 minutes or more. Even the same thing.

  Here, the amount of increase in volume resistivity of the intermediate transfer belt 44b depends on the application time (operating rate) of the primary transfer voltage and the transfer current to the intermediate transfer belt 44b. That is, in the present embodiment, the target current in each primary transfer portion 48 is fixed at 55 μA. Thus, although the increase amount of the volume resistivity depends on the application time (operating rate) of the primary transfer voltage, the transfer current changes even if the application time (operating rate) of the primary transfer voltage is the same. The amount of increase in volume resistivity changes. For example, in the present embodiment, the target current is 55 μA, and the application time to be integrated with respect to the voltage application for 1 hour is 1 hour (first value Ta). However, when the transfer current is different, the application to be integrated is performed. The time needs to be converted based on (transfer current / 55 μA). Specifically, for example, when the transfer current is set from 55 μA (first current value) to 110 μA (second current value) which is twice, the increase amount of the volume resistivity is approximately doubled. For this reason, the application time integrated in the voltage application for one hour is converted to two hours (second value Tb = 110/55). The first predetermined value 50 hours and the second predetermined value 10% are used as they are. That is, when the current value supplied to the intermediate transfer belt 44b from each primary transfer power supply 75 is 55 μA, the control unit 30 integrates the application time to be integrated in voltage application for one hour as one hour. In addition, when the absolute value of the current value is 110 μA, which is larger than 55 μA, the control unit 30 integrates the voltage application for 1 hour as 2 hours larger than 1 hour even if the actual voltage application is 1 hour. Do.

  The display procedure of the replacement alarm will be described in detail based on the flowchart shown in FIG. Storage and calculation of the application time and stop time of the primary transfer voltage are performed by the timer storage unit / arithmetic unit (timer) 31h (see FIG. 2) of the control unit 30. In the present embodiment, the timer storage unit / calculation unit 31h also functions as a timer that measures the application time of the primary transfer voltage as a value related to the amount of energization. Here, as a value related to the amount of energization, an operation rate R1 obtained by dividing the integrated value of the energization times after the start of use of the intermediate transfer belt 44b measured by the timer by the elapsed time after the start of use is also used. There is. When the image formation is completed (step S90), the application time T1 of the primary transfer voltage from the start of use of the intermediate transfer belt 44b and the non-application stop time T2 are acquired from the timer storage unit / operation unit 31h (step S91). The CPU 31 performs conversion based on (transfer current / 55 μA) when acquiring the application time T1 and the stop time T2. The CPU 31 adds the acquired application time T1 and stop time T2 to calculate an elapsed time (total period) T0 after the start of use of the intermediate transfer belt 44b (step S92).

  The CPU 31 divides the application time T1 after the start of use of the intermediate transfer belt 44b by the elapsed time T0 after the start of use to calculate the operation rate R1 of the primary transfer power supply 75 (step S93). Here, although the CPU 31 calculates the operating rate R1, the application time of the primary transfer voltage from the start of use is divided by the number of days elapsed after the start of use to calculate the application time of the primary transfer voltage per day, It may be used for subsequent judgments. The CPU 31 determines whether the application time T1 of the primary transfer voltage after the start of use of the intermediate transfer belt 44b has exceeded 50 hours (step S94). When the CPU 31 determines that the application time T1 of the primary transfer voltage after the start of use of the intermediate transfer belt 44b exceeds 50 hours, the operation rate R1 of the primary transfer power supply 75 after the start of use of the intermediate transfer belt 44b is 10%. It is determined whether it is above or not (step S95).

  If the CPU 31 determines that the operation rate R1 of the primary transfer power supply 75 after the start of use is 10% or more, it displays a replacement alarm on the display unit 70a (step S96). If the CPU 31 determines that the operation rate R1 of the primary transfer power supply 75 is not 10% or more, the CPU 31 does not display the replacement alarm on the display unit 70a (step S97), and prepares for the next image formation. Similarly, when the CPU 31 determines that the application time T1 of the primary transfer voltage from the start of use of the intermediate transfer belt 44b does not exceed 50 hours, the replacement alarm is not displayed on the display unit 70a (step S97) , Prepare for the end of the next image formation.

  As described above, according to the image forming apparatus 1 of the present embodiment, after the application time T1 of the primary transfer voltage reaches 50 hours, the control unit 30 sets the operation rate R1 of the primary transfer power supply 75 at 10% or more. If the intermediate transfer belt 44b has been replaced, the display unit 70a displays an intermediate transfer belt 44b replacement alarm. By using the image forming apparatus 1 having such a configuration, it is possible to accurately determine the replacement time of the intermediate transfer belt 44b. Therefore, it is possible to prevent image defects caused by the uneven resistance of the intermediate transfer belt 44b in advance, and to separately determine the original replacement timing slightly before the life of the intermediate transfer belt 44b. The average replacement time of 44b can be extended.

Eighth Embodiment
Next, an eighth embodiment of the present invention will be described in detail with reference to FIG. The present embodiment differs from the seventh embodiment in that the image formation is performed in the black and white mode. However, since the other configuration is the same as that of the seventh embodiment, the reference numerals are the same, and the detailed description will be omitted.

  The display procedure of the replacement alarm will be described in detail based on the flowchart shown in FIG. First, image formation ends (step S100). The application time T1 and stop time T2 of the primary transfer voltage from the start of use of the intermediate transfer belt 44b and the operation time T3 of the black and white mode from the start of use of the intermediate transfer belt 44b are obtained from the timer storage unit / operation unit 31h (Step S101). As in the sixth embodiment, the volume resistivity of the intermediate transfer belt 44b hardly changes even when an image is formed in the black and white mode, and the operation time T3 of the black and white mode is treated as the stop time. That is, the value regarding the amount of energization here, that is, the application time T4 of the primary transfer voltage is the application of the primary transfer voltage in the full color mode excluding the operation time T3 of the primary transfer voltage in the black and white mode from the total application time T1 of the primary transfer voltage. It means time T4. Therefore, the CPU 31 subtracts the operation time T3 of the black and white mode from the total application time T1 after the start of use (step S102). Since the procedure of subsequent step S92-step S97 is the same as that of 7th Embodiment, it carries out the code | symbol same and abbreviate | omits detailed description.

  As described above, according to the image forming apparatus 1 of the present embodiment, the control unit 30 applies the primary transfer voltage in the full color mode calculated by subtracting the operation time T3 of the black and white mode from the application time T1 after the start of use. I'm using time T4. Then, after the application time T4 of the primary transfer voltage in full color mode reaches 50 hours, when the operation rate R1 of the primary transfer power source 75 is 10% or more, the display unit 70a displays an alarm for replacing the intermediate transfer belt 44b. Do. By using the image forming apparatus 1 having such a configuration, it is possible to accurately determine the replacement timing of the intermediate transfer belt 44b even when the black and white mode is used.

  In the image forming apparatuses 1 according to the seventh and eighth embodiments described above, the operating rate R1 of the primary transfer power source 75 is used, but the invention is not limited to this. For example, it is only necessary to calculate the amount of charge to be applied to the intermediate transfer belt 44b and the duration of the application.

The ninth embodiment
Next, a ninth embodiment of the present invention will be described in detail with reference to FIG. In the present embodiment, the number of image formation on a day when the number of image formation per day exceeds a predetermined value is integrated, and the replacement timing of the intermediate transfer belt 44b is determined based on the integration value. And the configuration is different. However, since the other configuration is the same as that of the first embodiment, the reference numerals are the same, and the detailed description will be omitted. Further, in the present embodiment, the image formation is performed in the full color mode, and the target current in each of the primary transfer portions 48 is 55 μA.

  In the present embodiment, the control unit 30 integrates the number of image formations P5 when the number of image formations P5 acquired every day is larger than 10,000 (first threshold). Then, when the integrated value reaches 500,000 sheets (second threshold), the control unit 30 issues an alarm for replacing the intermediate transfer belt 44b and displays it on the display unit 70a. Here, 10,000 sheets correspond to the first threshold value, and 500,000 sheets correspond to the second threshold value, but it goes without saying that the present invention is not limited thereto.

  Here, the amount of increase in the volume resistivity of the intermediate transfer belt 44b depends on the number of images formed and the transfer current to the intermediate transfer belt 44b. That is, in the present embodiment, since the target current in each primary transfer portion 48 is fixed at 55 μA, the amount of increase in volume resistivity is dependent on the number of image formations, but the number of image formations is the same. Also, the amount of increase in volume resistivity changes as the transfer current changes. For example, in the present embodiment, the target current is 55 μA, and the number of image formations to be integrated in one image formation is one sheet (first value Pa), but when the transfer current is different, the image formation is integrated. It is necessary to convert the number of sheets based on (transfer current / 55 μA). Specifically, for example, when the transfer current is set from 55 μA (first current value) to 110 μA (second current value) which is twice, the increase amount of the volume resistivity is approximately doubled. Therefore, the number of image formations to be integrated in one image formation is converted to two (second value Pb = 110/55). The first threshold of 10,000 sheets and the second threshold of 500,000 sheets are used as they are. That is, when the current value supplied to the intermediate transfer belt 44b from each primary transfer power source 75 is 55 μA, the control unit 30 integrates the number of sheets for image formation integrated in one image formation as one sheet. In addition, when the absolute value of the current value is 110 μA, which is larger than 55 μA, the control unit 30 sets two sheets larger than one in one image formation even if the actual number of image formation is one. Accumulate.

  The display procedure of the replacement alarm will be described in detail based on the flowchart shown in FIG. Storage and calculation of the number of image formations are performed by the image formation counter storage unit / calculation unit (counter) 31g (see FIG. 2) of the control unit 30. In the present embodiment, the image formation counter storage unit / calculation unit 31g also functions as a counter that counts the number of image formation sheets as a value related to the amount of current. When the image formation is completed (step S110), the number P5 of image formation on that day is acquired from the image formation counter storage unit / calculation unit 31g (step S111). When the image formation counter storage unit / calculation unit 31g integrates the number of image formations P5 of the day, the number of image formations converted based on (transfer current / 55 μA) is integrated for each image formation. doing. The CPU 31 determines whether the number of image formations P5 on that day exceeds 10,000 (step S112). If the CPU 31 determines that the number P5 of image formation on that day exceeds 10,000, the number P5 of image formation is integrated in the image formation counter storage unit / calculation unit 31g (step S113). Subsequently, the CPU 31 determines whether the number of image formations accumulated in the counter is 500,000 or more (step S114).

  If the CPU 31 determines that the number of times of image formation accumulated in the counter is 500,000 or more, it displays an exchange alarm on the display unit 70a (step S115). If the CPU 31 determines that the number of times of image formation accumulated in the counter is not 500,000 or more, it does not display the replacement alarm on the display unit 70a, and prepares for the end of the next image formation (step S116). Similarly, when the CPU 31 determines that the number of formed images P5 of the day does not exceed 10,000, the exchange alarm is not displayed on the display unit 70a, and integration is not performed in the image formation counter storage unit / calculation unit 31g. In preparation for the end of the next image formation (step S116).

  Here, also in the present embodiment, the total image formation from the initial use of the intermediate transfer belt 44b to the output time of the exchange information for prompting replacement according to the daily usage amount (the number of images formed and the electrification amount) of the image forming apparatus 1 The number has been changed. That is, when the image formation is performed continuously under the first operation condition where the number of image formation P5 formed on one day is 10,000 sheets (predetermined number) or more, for example, 20,000 sheets, the exchange information of the intermediate transfer belt 44b is The number of formed images up to the time of output is 500,000 (the first number). On the other hand, when images are formed continuously on the second day under the second operation condition that the number of image formation formed on one day is less than 10,000, replacement information on the intermediate transfer belt 44b is not output (step S116), The number of times of image formation until the time of output is the second number which is larger than the first number.

  As described above, according to the image forming apparatus 1 of the present embodiment, the control unit 30 integrates the number of image formations P5 when the number of image formations P5 of the day is larger than 10,000 and the integration value is 50. If the number of sheets has reached ten thousand, the intermediate transfer belt 44b replacement alarm is displayed on the display 70a. By using the image forming apparatus 1 having such a configuration, it is possible to accurately determine the replacement time of the intermediate transfer belt 44b. Therefore, it is possible to prevent image defects caused by the uneven resistance of the intermediate transfer belt 44b in advance, and to separately determine the original replacement timing slightly before the life of the intermediate transfer belt 44b. The average replacement time of 44b can be extended.

Tenth Embodiment
Next, a tenth embodiment of the present invention will be described in detail with reference to FIG. The present embodiment differs from the ninth embodiment in that the image formation is performed in the black and white mode. However, since the other configuration is the same as that of the ninth embodiment, the same reference numerals are used and the detailed description is omitted.

  The display procedure of the replacement alarm will be described in detail based on the flowchart shown in FIG. First, image formation ends (step S120). The image formation number P4 of the day and the image formation number P5 in the monochrome mode of the day are acquired from the image formation counter storage unit / calculation unit 31g (step S121). Similar to the sixth embodiment, assuming that the volume resistivity of the intermediate transfer belt 44b hardly changes even when the image is formed in the black and white mode, the number P6 of images formed in the black and white mode of the day is excluded from the number P5 of images formed on that day. To do. That is, the value relating to the amount of energization here, that is, the number of image formations P7, means the number of images formed in the full color mode P7 excluding the number of images formed in the black and white mode P6 from the total number of images formed P5. Therefore, the CPU 31 subtracts the number of formed images P6 in the monochrome mode of that day from the number of formed images P5 of that day (step S122). Since the procedure of subsequent step S112-step S116 is the same as that of 9th Embodiment, it carries out the code | symbol same and abbreviate | omits detailed description.

  As described above, according to the image forming apparatus 1 of the present embodiment, the control unit 30 calculates the number of image formations in the full color mode calculated by subtracting the number of image formations P6 in the monochrome mode of that day from the number of image formations P5 of that day. I am using P7. Then, when the image formation number P7 in the full color mode is larger than 10,000, the image formation number P7 is integrated, and when the integration value reaches 500,000, the intermediate transfer belt 44b replacement alarm is displayed on the display unit 70a. Display on By using the image forming apparatus 1 having such a configuration, it is possible to accurately determine the replacement timing of the intermediate transfer belt 44b even when the black and white mode is used.

Eleventh Embodiment
Next, an eleventh embodiment of the present invention will be described in detail with reference to FIG. The present embodiment differs from the ninth embodiment in that the time to replace the intermediate transfer belt 44 b is determined based on the operation rate of the primary transfer power supply 75. However, since the other configuration is the same as that of the ninth embodiment, the same reference numerals are used and the detailed description is omitted. Further, in the present embodiment, the image formation is performed in the full color mode, and the target current in each of the primary transfer portions 48 is 55 μA.

  In the present embodiment, the number of image forming sheets of 10,000 sheets / day in the ninth embodiment is converted to the operation rate of the primary transfer power supply 75. In the image forming apparatus 1 of the present embodiment, for example, when it is possible to form an image of 100 sheets per minute, it takes 100 minutes to output 10,000 sheets. At this time, the ratio of the application time of the primary transfer voltage is 100 minutes / 24 hours = about 7%. Therefore, when the operation rate R2 of the primary transfer power supply 75 on that day exceeds 7% (first threshold), the application time of the primary transfer voltage is integrated. Further, 500,000 sheets in the ninth embodiment are 80 hours (second threshold) in terms of application time of the primary transfer voltage. Here, 7% corresponds to the first threshold, and 80 hours corresponds to the second threshold, but it goes without saying that the present invention is not limited thereto. Further, in the present embodiment, it is determined whether or not the operation rate R2 of the primary transfer power supply 75 on that day exceeds 7%, but it is not limited thereto. For example, the same is true even if the application time of the primary transfer voltage on that day is calculated and it is determined whether or not it exceeds 100 minutes.

  Here, the amount of increase in volume resistivity of the intermediate transfer belt 44b depends on the application time (operating rate) of the primary transfer voltage and the transfer current to the intermediate transfer belt 44b. That is, in the present embodiment, the target current in each primary transfer portion 48 is fixed at 55 μA. Thus, although the increase amount of the volume resistivity depends on the application time (operating rate) of the primary transfer voltage, the transfer current changes even if the application time (operating rate) of the primary transfer voltage is the same. The amount of increase in volume resistivity changes. For example, in the present embodiment, the target current is 55 μA, and the application time to be integrated with respect to the voltage application for 1 hour is 1 hour (first value Ta). However, when the transfer current is different, the application to be integrated is performed. The time needs to be converted based on (transfer current / 55 μA). Specifically, for example, when the transfer current is set from 55 μA (first current value) to 110 μA (second current value) which is twice, the increase amount of the volume resistivity is approximately doubled. For this reason, the application time integrated in the voltage application for one hour is converted to two hours (second value Tb = 110/55). The first threshold 7% and the second threshold 80 hours are used as they are. That is, when the current value supplied to the intermediate transfer belt 44b from each primary transfer power supply 75 is 55 μA, the control unit 30 integrates the application time to be integrated in voltage application for one hour as one hour. In addition, when the absolute value of the current value is 110 μA, which is larger than 55 μA, the control unit 30 integrates the voltage application for 1 hour as 2 hours larger than 1 hour even if the actual voltage application is 1 hour. Do.

  The display procedure of the replacement alarm will be described in detail based on the flowchart shown in FIG. Storage and calculation of the application time and stop time of the primary transfer voltage are performed by the timer storage unit / arithmetic unit (timer) 31h (see FIG. 2) of the control unit 30. In the present embodiment, the timer storage unit / calculation unit 31h also functions as a timer that measures the application time of the primary transfer voltage as a value related to the amount of energization. Here, as a value related to the amount of energization, an operation rate R2 obtained by dividing the integrated value of the energization times after the start of use of the intermediate transfer belt 44b measured by the timer by the elapsed time after the start of use is also used. There is. When the image formation is completed (step S130), the application time T5 and the stop time T6 of the primary transfer voltage of the day are acquired from the timer storage unit / calculation unit 31h (step S131). The CPU 31 performs conversion based on (transfer current / 55 μA) when acquiring the application time T5 and the stop time T6. The CPU 31 adds the acquired application time T5 and stop time T6 to calculate the elapsed time (total period) T7 of that day (step S132).

  The CPU 31 divides the application time T5 of the day by the elapsed time T7 of the day to calculate the operation rate R2 of the primary transfer power supply 75 of the day (step S133). Here, although the CPU 31 calculates the operating rate R2, the application time of the primary transfer voltage from the start of use is divided by the number of days elapsed after the start of use to calculate the application time of the primary transfer voltage per day, It may be used for subsequent judgments. The CPU 31 determines whether the operation rate R2 of the primary transfer power supply 75 on that day exceeds 7% (step S134). If the CPU 31 determines that the operation rate R2 of the primary transfer power supply 75 on that day exceeds 7%, it integrates the application time T5 of the primary transfer voltage on that day in the image formation counter storage unit / calculation unit 31g (step S135). . Subsequently, the CPU 31 determines whether the application time of the primary transfer voltage accumulated in the image formation counter storage unit / calculation unit 31g is 80 hours or more (step S136).

  When the CPU 31 determines that the application time of the primary transfer voltage accumulated in the image formation counter storage unit / calculation unit 31g is 80 hours or more, it displays a replacement alarm on the display unit 70a (step S137). If the CPU 31 determines that the number of times of image formation accumulated in the image formation counter storage unit / calculation unit 31g is not 80 hours or more, the CPU 31 prepares for the end of the next image formation without displaying the replacement alarm on the display unit 70a. (Step S138). Similarly, when the CPU 31 determines that the operation rate R2 of the day does not exceed 7%, the exchange alarm is not displayed on the display unit 70a, and is not integrated in the image formation counter storage unit / calculation unit 31g, In preparation for the end of the next image formation (step S138).

  As described above, according to the image forming apparatus 1 of the present embodiment, the control unit 30 integrates the application time T5 of the primary transfer voltage when the operation rate R2 of the primary transfer power supply 75 on that day is larger than 7%. . Then, when the integrated value reaches 80 hours or more, a replacement alarm of the intermediate transfer belt 44b is displayed on the display unit 70a. Therefore, it is possible to prevent image defects caused by the uneven resistance of the intermediate transfer belt 44b in advance, and to separately determine the original replacement timing slightly before the life of the intermediate transfer belt 44b. The average replacement time of 44b can be extended.

Twelfth Embodiment
Next, a twelfth embodiment of the present invention will be described in detail with reference to FIG. The present embodiment is different from the eleventh embodiment in that the image formation is performed in the black and white mode. However, since the other configuration is the same as that of the eleventh embodiment, the same reference numerals are used and the detailed description is omitted.

  The display procedure of the replacement alarm will be described in detail based on the flowchart shown in FIG. First, image formation ends (step S140). The application time T5 and stop time T6 of the primary transfer voltage on that day, and the operation time T8 of the monochrome mode on that day are acquired from the timer storage unit / operation unit 31h (step S141). As in the tenth embodiment, the volume resistivity of the intermediate transfer belt 44b hardly changes even when an image is formed in the black and white mode, and the operation time T8 of the black and white mode is treated as the stop time. That is, the value regarding the amount of energization here, that is, the application time T9 of the primary transfer voltage is the application of the primary transfer voltage in the full color mode excluding the operation time T8 of the primary transfer voltage in the black and white mode from the total application time T5 of the primary transfer voltage. It means time T9. Therefore, the CPU 31 subtracts the operation time T8 of the monochrome mode on that day from the application time T5 on that day (step S142). Since the procedure of subsequent step S132-step S138 is the same as that of 11th Embodiment, it carries out the code | symbol same and abbreviate | omits detailed description.

  As described above, according to the image forming apparatus 1 of the present embodiment, the control unit 30 applies the primary transfer voltage in the full color mode calculated by subtracting the operation time T8 of the black and white mode of that day from the application time T5 of that day. I am using time T9. The application time T9 of the primary transfer voltage is integrated when the availability R2 of the primary transfer power source 75 obtained by the application time T9 of the primary transfer voltage in the full color mode is larger than 7%. Then, when the integrated value reaches 80 hours or more, a replacement alarm of the intermediate transfer belt 44b is displayed on the display unit 70a. By using the image forming apparatus 1 having such a configuration, it is possible to accurately determine the replacement time of the intermediate transfer belt 44b even in the black and white mode.

  Although the operation rate R2 of the primary transfer power supply 75 is used in the image forming apparatus 1 of the eleventh and twelfth embodiments described above, the present invention is not limited to this. For example, it is only necessary to calculate the amount of charge to be applied to the intermediate transfer belt 44b and the duration of the application.

  Further, the display procedure of the exchange alarm shown in each of the image forming apparatuses 1 according to the fifth to twelfth embodiments described above is only an example, and the present invention is not limited to them. You may replace it suitably.

The thirteenth embodiment
Next, a thirteenth embodiment of the present invention will be described in detail with reference to FIG. The present embodiment is different from the first embodiment in that an apparatus different from the control unit 30 of the image forming apparatus 1 displays an intermediate transfer belt 44 b replacement alarm. However, the configuration of the image forming apparatus 1 other than the control unit 30 is the same as that of the first embodiment, so the reference numerals are the same and detailed description will be omitted.

  The present embodiment relates to an image forming system 100, and the image forming system 100 includes an image forming apparatus 1, a server apparatus 110, and an external display apparatus (information transmission apparatus) 120. The image forming apparatus 1 is installed in a user's use environment such as a market, the server apparatus 110 is installed in a management unit of a management company of the image forming system 100, and the external display apparatus 120 is used in a service person's use environment such as a sales company. is set up. The image forming apparatus 1, the server apparatus 110, and the external display apparatus 120 are connected by a network 130.

  The image forming apparatus 1 is provided with a control unit 30 and a transmitting unit 35 which is a module for adding a protocol to communication between the image forming apparatus 1 and the server apparatus 110. For example, the control unit 30 acquires the number of image formations per day and sends the number to the transmission unit 35. The transmission unit 35 transmits the number of image formations for one day sent from the control unit 30 to the server apparatus 110 via the network 130.

  The server apparatus 110 is constituted by, for example, a computer installed in a management unit, and includes a transmission / reception unit 111 that transmits / receives data to / from the network 130, a control unit 112, and a database 113 including an HDD or the like. There is. The transmission / reception unit 111 can communicate with the transmission unit 35 and receives the value regarding the amount of energization transmitted by the transmission unit 35. In the server apparatus 110, the number of sheets of the image formed on one day transmitted from the image forming apparatus 1 is received by the transmission / reception unit 111, and the control unit 112 associates the number with the date, serial number, model, etc. The database 113 can store information, and the control unit 112 can read and write, for example, the number of images formed on one day sent from the image forming apparatus 1. The control unit 112 can also transmit information stored in the database 113 to the transmission / reception unit 121 via the transmission / reception unit 111 when the external display device 120 accesses the control unit 112.

  The external display device 120 is, for example, a terminal device configured by a computer installed at a sales company. The external display device 120 includes a transmission / reception unit (reception unit) 121 that transmits / receives data to / from the network 130, a control unit 122, an operation unit 123, and a display unit 124 formed of a liquid crystal panel or the like. The transmission / reception unit 121 can communicate with the transmission / reception unit 111 and receives the value regarding the amount of energization transmitted by the transmission / reception unit 111. The external display device 120 accesses the database 113 of the server apparatus 110 via the transmission / reception unit 121 and the network 130 by the operation of the operation unit 123 by the serviceman, and stores the number of images formed on a given image forming apparatus 1 per day Get the The control unit 122 determines based on the acquired information whether or not the replacement time of the intermediate transfer belt 44 b of the image forming apparatus 1 has arrived. The determination procedure at that time can be the same as that in any of the first to twelfth embodiments. Further, in the present embodiment, the number of sheets on which images are formed per day is transmitted from the image forming apparatus 1 to the server apparatus 110. However, the present invention is not limited thereto. For example, information such as the application time of the primary transfer voltage You may make it transmit. In any case, based on the information transmitted to the server apparatus 110, it is determined whether the time to replace the intermediate transfer belt 44b has been reached.

  When it is determined that the replacement time of the intermediate transfer belt 44 b of the image forming apparatus 1 has arrived, the control unit 122 of the external display device 120 displays an intermediate transfer belt 44 b replacement alarm on the display unit 124. Thus, the serviceman obtains information that the intermediate transfer belt 44b of the image forming apparatus 1 has reached the replacement time, moves to the installation location of the image forming apparatus 1, and replaces the intermediate transfer belt 44b. Can.

  As described above, according to the image forming system 100 of the present embodiment, it is possible to prevent image defects caused by the uneven resistance of the intermediate transfer belt 44b. At the same time, the average replacement time of the intermediate transfer belt 44b can be extended by individually determining the original replacement time that is slightly before the life of the intermediate transfer belt 44b.

  According to the image forming system 100 of the present embodiment, the external display device 120 determines whether the intermediate transfer belt 44 b has reached the replacement time. Therefore, there is no need to determine the replacement time of the intermediate transfer belt 44b in the control unit 30 of the image forming apparatus 1, and the control unit 30 can be simplified.

  In the image forming system 100 of the present embodiment described above, the external display device 120 determines whether the intermediate transfer belt 44b has reached the replacement time, but the present invention is not limited to this. For example, the control unit 112 of the server apparatus 110 may make a determination based on the information stored in the database 113, and the server apparatus 110 may transmit the result to the external display apparatus 120.

  Alternatively, information such as the number of image formations and the primary transfer voltage may be transmitted directly from the image forming apparatus 1 to the external display device 120 without passing through the server device 110. In this case, the control unit 122 of the external display device 120 determines whether it is time to replace the intermediate transfer belt 44b. According to this, the determination means and the display unit 124 can be realized by the same external display device 120.

Reference Signs List 1 image forming apparatus 30 control unit (output unit) 31 g image formation counter storage unit / calculation unit (counter) 31 h timer storage unit / calculation unit (timer) 35 transmission unit 51 photosensitive drum (Image carrier) 51c: photosensitive drum (image carrier) 51k: photosensitive drum (image carrier) 51m: photosensitive drum (image carrier) 51y: photosensitive drum (image carrier) 44b: intermediate transfer Belt, 47c: primary transfer roller (second energizing unit), 47k: primary transfer roller (second energizing unit), 47y: primary transfer roller (first energizing unit), 61: upstream device (first energizing unit) 61e: first cleaning power source (energization unit) 62: downstream apparatus (second energization unit) 62e: second cleaning power source (energization unit) 75: primary transfer power source (energization unit) 76: secondary Transfer power supply (current-carrying unit), 100: Image formation system Arm, 120 ... external display device (information transmitting apparatus), 121 ... receiving portion (receiving portion).

Claims (11)

An image carrier,
An intermediate transfer belt having an elastic layer, to which a toner image is transferred from the image bearing member;
An energizing unit capable of energizing the intermediate transfer belt;
An output unit that outputs replacement information for prompting replacement of the intermediate transfer belt;
The first image forming number from the start of the first use of the intermediate transfer belt to the output of the exchange information is such that the amount of current supplied from the power supply unit to the intermediate transfer belt from one day is equal to or greater than a predetermined amount. In the case of conducting electricity continuously on operating conditions, it is the first number, and on the second operating condition the energizing amount supplied to the intermediate transfer belt from the energizing unit on the 1st day is less than the predetermined amount. If the second number is larger than the first number,
An image forming apparatus characterized by The output unit is configured such that, after the integrated value of the values relating to the amount of energization from the start of use exceeds a first predetermined value, the value relating to the amount of energization per day from the start of use is a second predetermined value If the above, the exchange information is output,
The image forming apparatus according to claim 1, The output unit integrates values relating to the energization amount on a day when the value regarding the energization amount per day is larger than the first threshold, and when the integrated value reaches the second threshold, the exchange information is output. Output,
The image forming apparatus according to claim 1, It has a counter that counts the number of images formed
The value regarding the amount of energization is the number of image formations counted by the counter.
The image forming apparatus according to claim 2 or 3, wherein A timer for measuring an energization time of the intermediate transfer belt;
The value regarding the amount of energization is the energization time measured by the timer,
The image forming apparatus according to claim 2 or 3, wherein A timer for measuring an energization time of the intermediate transfer belt;
The value related to the amount of energization is an operation rate obtained by dividing the integrated value of energization times after the start of use of the intermediate transfer belt measured by the timer by the elapsed time after the start of use.
The image forming apparatus according to claim 2 or 3, wherein The output unit integrates a value related to the amount of energization as a first value when the current value supplied to the intermediate transfer belt from the energizing unit is a first current value, and the absolute value of the current value When the second current value is larger than the first current value, the second value larger than the first value is used even if the value related to the actual energization amount is the first value. Accumulate,
The image forming apparatus according to any one of claims 2 to 6, wherein The intermediate transfer belt is rotatable,
The energizing unit is a first energizing unit capable of energizing the intermediate transfer belt at a first position, and a second position downstream of the first position in the rotational direction of the intermediate transfer belt. A second energizing unit capable of energizing the intermediate transfer belt;
When the area of the intermediate transfer belt which has passed the first position when the first energizing unit is energized passes the second position, the output unit is configured to connect the intermediate transfer belt to the intermediate transfer belt. When energized, the first voltage and the first current of the first energizing means at the time of energization at the first position, and the second energization at the time of energization when the region passes the second position Outputting the exchange information based on a second voltage and a second current of the means;
The image forming apparatus according to claim 1, A plurality of image carriers are used, and a plurality of color modes in which images are formed in a plurality of colors by the plurality of image carriers, and a single-color image using only the image carrier among the plurality of image carriers It can be executed by switching between the single-color mode to be formed,
The value regarding the amount of energization is a value regarding the amount of energization in the multiple color mode,
The image forming apparatus according to any one of claims 1 to 8, wherein An image carrier,
An intermediate transfer belt having an elastic layer, to which a toner image is transferred from the image bearing member;
An energizing unit capable of energizing the intermediate transfer belt;
An output unit that outputs replacement information for prompting replacement of the intermediate transfer belt;
The number of image formations from the start of the first use of the intermediate transfer belt to the output of the exchange information is continuous image formation under the first operation condition in which the number of image formations formed on one day is a predetermined number or more. In the case of the first number of sheets, when images are formed continuously on the second day under the second operation condition that the number of image formation formed on one day is less than the predetermined number, the second number is larger than the first number. is there,
An image forming apparatus characterized by An intermediate transfer belt having an image carrier, an elastic layer, to which a toner image is transferred from the image carrier, a conducting part capable of energizing the intermediate transfer belt, and a transfer from the conducting part to the intermediate transfer belt An image forming apparatus having a transmitting unit that transmits a value related to the amount of current supplied;
Information that is communicable with the transmission unit and has a reception unit that receives the value regarding the amount of energization transmitted by the transmission unit, and an output unit that outputs replacement information for prompting replacement of the intermediate transfer belt And a transmitting device,
The first image forming number from the start of the first use of the intermediate transfer belt to the output of the exchange information is such that the amount of current supplied from the power supply unit to the intermediate transfer belt from one day is equal to or greater than a predetermined amount. In the case of conducting electricity continuously on operating conditions, it is the first number, and on the second operating condition the energizing amount supplied to the intermediate transfer belt from the energizing unit on the 1st day is less than the predetermined amount. If the second number is larger than the first number,
An image forming system characterized by

Images