Image forming device

Abstract

To provide a technique to avoid a reduction in quality of image formation due to attachment of foreign substances to photoreceptor drums.SOLUTION: An image forming apparatus 1 comprises: a drum cartridge 20; a main body memory 513; and a control unit 51. The drum cartridge 20 has photoreceptor drums 21 rotatable about a rotation axis. The main body memory 513 stores the number of rotations of the photoreceptor drums 21. The control unit 51 calculates the attachment amount Y of foreign substances attached to the photoreceptor drums 21 based on the number of rotations of the photoreceptor drums 21 stored by the main body memory 513 and parameters A, B indicating how easily foreign substances are attached to the photoreceptor drums 21. The control unit 51 determines if the calculated attachment amount Y exceeds a predetermined threshold Th_5 or Th_5e.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to an image forming apparatus. [Background technology]

[0002] Conventionally, electrophotographic image forming devices such as laser printers and LED printers are known. A drum cartridge is used in the image forming device. The drum cartridge has a photosensitive drum equipped with a photosensitive layer. The photosensitive drum has a photosensitive layer. An electrostatic latent image is formed by exposing the charged photosensitive layer to light. Then, the electrostatic latent image is developed with toner and then transferred to a medium such as paper. A conventional image forming device is described in, for example, Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-54058 A Summary of the Invention [Problem to be solved by the invention]

[0004] Foreign matter may adhere to the surface of the photoconductor drum. For example, the foreign matter may be silica contained in toner. If the amount of foreign matter adhering to the photoconductor drum increases, the quality of image formation may be significantly reduced.

[0005] An object of the present disclosure is to provide a technique for preventing degradation of image formation quality due to adhesion of foreign matter to a photosensitive drum. [Means for solving the problem]

[0006] In order to solve the above problem, a first aspect is an image forming device comprising: a drum cartridge having a photosensitive drum rotatable about a rotation axis; a memory that stores the rotation speed of the photosensitive drum; and a control unit, wherein the control unit is capable of executing an adhesion amount calculation process that calculates an amount of foreign matter adhering to the photosensitive drum based on the rotation speed of the photosensitive drum stored in the memory and a parameter that indicates the ease with which foreign matter adheres to the photosensitive drum; and a threshold determination process that determines whether the adhesion amount calculated by the adhesion amount calculation process exceeds a predetermined threshold.

[0007] A second aspect is an image forming apparatus of the first aspect, wherein the adhesion amount calculation process includes a process in which the control unit calculates an increase in the amount of foreign matter adhering to the photosensitive drum, the increase corresponding to the rotation speed of the photosensitive drum stored in the memory, and a process in which the control unit calculates the adhesion amount by accumulating the increase.

[0008] A third aspect is an image forming apparatus of the first or second aspect, further comprising a developing roller, and the parameters include a first parameter indicating the tendency of foreign matter to adhere from the developing roller to the photosensitive drum.

[0009] A fourth aspect is the image forming apparatus of the third aspect, further comprising a drive unit that moves the developing roller between a contact position where the developing roller is in contact with the photosensitive drum and a spaced position where the developing roller is spaced from the photosensitive drum, and the first parameter is a parameter that makes it easier for foreign matter to adhere to the photosensitive drum when the developing roller is in the contact position than when the developing roller is in the spaced position.

[0010] A fifth aspect is an image forming apparatus of the third or fourth aspect, further comprising a drive unit that moves the developing roller between a contact position where the developing roller is in contact with the photosensitive drum and a separated position where the developing roller is separated from the photosensitive drum, and the first parameter is a parameter that makes the increase amount calculated by the control unit in accordance with the rotation speed of the photosensitive drum when the developing roller is in the separated position smaller than the increase amount calculated by the control unit in accordance with the rotation speed of the photosensitive drum when the developing roller is in the contact position.

[0011] A sixth aspect is an image forming device of any one of the first to fifth aspects, wherein the drum cartridge further includes a cleaning member for cleaning the surface of the photosensitive drum, and the parameters include a second parameter indicating the ease with which foreign matter adheres from the cleaning member to the photosensitive drum.

[0012] A seventh aspect is an image forming device according to any one of the third to fifth aspects, wherein the drum cartridge further includes a cleaning member for cleaning the surface of the photosensitive drum, and the parameters further include a second parameter indicating the tendency of foreign matter to adhere from the cleaning member to the photosensitive drum, and the adhesion amount calculation process calculates the amount of foreign matter adhering to the photosensitive drum based on the rotation speed of the photosensitive drum stored in the memory, the first parameter, and the second parameter.

[0013] An eighth aspect is the image forming apparatus of the sixth or seventh aspect, wherein the second parameter is a parameter that increases or decreases the amount of adhesion calculated by the control unit.

[0014] A ninth aspect is an image forming apparatus according to any one of the first to eighth aspects, further comprising an erase lamp that discharges electricity from the surface of the photosensitive drum by irradiating light onto the surface of the photosensitive drum, wherein the control unit is capable of executing an illumination determination process that determines whether the erase lamp is lit, and the parameter is a parameter that increases the amount of foreign matter adhering to the photosensitive drum when it is determined in the illumination determination process that the erase lamp is lit compared to the amount of foreign matter adhering to the photosensitive drum when it is determined in the illumination determination process that the erase lamp is not lit.

[0015] A tenth aspect is an image forming apparatus according to any one of the first to ninth aspects, further comprising a developing roller, and the parameter is a parameter that varies the amount of adhesion based on at least one of the rotational speed of the photosensitive drum or the rotational speed of the developing roller.

[0016] An eleventh aspect is an image forming apparatus according to any one of the first to tenth aspects, further comprising a developing roller, wherein the control unit is capable of executing a storage process for storing a cumulative number of rotations of the developing roller in the memory, and the parameter is a parameter for varying the amount of adhesion based on the cumulative number of rotations of the developing roller stored in the memory.

[0017] A twelfth aspect is an image forming apparatus according to any one of the first to eleventh aspects, further comprising a charger that charges the photosensitive drum, and the parameter is a parameter that increases the amount of adhesion calculated by the control unit more significantly the greater the magnitude of the voltage that the charger applies to the photosensitive drum.

[0018] A thirteenth aspect is an image forming apparatus according to any one of the first to twelfth aspects, further comprising a temperature detector for detecting temperature, the parameter being a parameter for varying the amount of adhesion based on the temperature detected by the temperature detector.

[0019] A 14th aspect is an image forming apparatus according to any one of the first to 13th aspects, further comprising a humidity detector for detecting humidity, the parameter being a parameter for varying the amount of adhesion based on the humidity detected by the humidity detector.

[0020] A 15th aspect is an image forming apparatus according to any one of the first to fourteenth aspects, further comprising a developing roller and a drive unit which moves the developing roller between a contact position in contact with the photosensitive drum and a separated position away from the photosensitive drum, and the adhesion amount calculation process includes a process in which the control unit calculates the adhesion amount based on at least one of the number of times the developing roller moves from the separated position to the contact position or the number of times the developing roller moves from the contact position to the separated position, the number of rotations of the photosensitive drum, and the parameters.

[0021] A 16th aspect is an image forming apparatus of the 15th aspect, in which the adhesion amount calculation process includes a process in which the control unit calculates the adhesion amount based on the number of times the developing roller moves from the separation position to the contact position, the number of times the developing roller moves from the contact position to the separation position, the rotation speed of the photosensitive drum, and the parameters.

[0022] A 17th aspect is an image forming device according to any one of the 1st to 16th aspects, wherein the threshold determination process includes a process in which the control unit determines whether the amount of adhesion exceeds a first threshold, and when the control unit determines through the threshold determination process that the amount of adhesion exceeds the first threshold, the control unit is capable of executing a usage restriction process that restricts use of the drum cartridge.

[0023] An 18th aspect is an image forming apparatus according to any one of the 1st to 17th aspects, further comprising a display, wherein the threshold determination process includes a process in which the control unit determines whether the amount of adhesion exceeds a first threshold, and when the threshold determination process determines that the amount of adhesion exceeds the first threshold, the control unit executes a display process in which the display displays information encouraging replacement of the drum cartridge.

[0024] A 19th aspect is an image forming apparatus according to any one of the 1st to 18th aspects, further comprising a communication interface for the control unit to communicate with a communication device via a network, and the control unit is capable of executing a transmission process for transmitting information for ordering a new drum cartridge to the communication device via the communication interface based on the amount of adhesion. Effect of the Invention

[0025] According to the image forming apparatuses of the first to nineteenth aspects, since the photosensitive drum rotates while contacting other members, the amount of foreign matter adhering to the photosensitive drum may vary depending on the number of rotations of the photosensitive drum. Therefore, the amount of foreign matter adhering to the photosensitive drum can be appropriately calculated based on the number of rotations of the photosensitive drum. In addition, by comparing the amount of foreign matter with a threshold value, an abnormality in the drum cartridge due to the adhesion of foreign matter can be detected.

[0026] According to the image forming apparatus of the second aspect, the amount of attached foreign matter can be appropriately calculated by accumulating the increase in the amount of foreign matter.

[0027] According to the image forming apparatus of the third aspect, the amount of foreign matter adhering to the photosensitive drum by the developing roller can be calculated based on the first parameter.

[0028] According to the fourth aspect of the image forming apparatus, the first parameter is used to estimate the increase in the amount of foreign matter adhering to the photosensitive drum when the developing roller is in contact with the photosensitive drum as greater than the increase in the amount of foreign matter adhering to the photosensitive drum when the developing roller is separated from the photosensitive drum. This allows the amount of foreign matter adhering to the photosensitive drum to be calculated appropriately.

[0029] According to the image forming apparatus of the ninth aspect, when the erase lamp is on, foreign matter may adhere more easily than when the erase lamp is off. Therefore, by making the increase amount when the erase lamp is on larger than the increase amount when the erase lamp is off, the amount of adhered foreign matter can be calculated appropriately.

[0030] According to the image forming apparatus of the tenth aspect, the likelihood of foreign matter adhering to the photosensitive drum may depend on the rotation speed of the photosensitive drum or the rotation speed of the developing roller, and therefore the amount of foreign matter adhering can be appropriately calculated based on the rotation speed of the photosensitive drum or the rotation speed of the developing roller.

[0031] According to the image forming apparatus of the eleventh aspect, the tendency of foreign matter to adhere to the photosensitive drum may depend on the deterioration of the toner. In addition, since the cumulative number of rotations of the developing roller increases as the printing process is performed, the deterioration of the toner may be correlated with the cumulative number of rotations of the developing roller. Therefore, the amount of foreign matter adhering due to the deterioration of the toner can be appropriately calculated based on the cumulative number of rotations of the developing roller.

[0032] According to the image forming apparatus of the twelfth aspect, the tendency of foreign matter to adhere to the photosensitive drum may depend on the magnitude of the voltage applied to the photosensitive drum, and therefore the amount of foreign matter adhered can be appropriately calculated based on the magnitude of the voltage applied to the photosensitive drum.

[0033] According to the image forming apparatus of the thirteenth aspect, the amount of attached foreign matter can be appropriately calculated based on the temperature.

[0034] According to the image forming apparatus of the fourteenth aspect, the amount of attached foreign matter can be appropriately calculated based on the humidity.

[0035] According to the image forming apparatus of the fifteenth aspect, when the developing roller comes into contact with the photosensitive drum or when the developing roller separates from the photosensitive drum, the force that the photosensitive drum receives from the developing roller changes, which can cause foreign matter to adhere to the photosensitive drum. Therefore, the amount of foreign matter adhered can be appropriately calculated based on the number of times that the developing roller comes into contact with the photosensitive drum or the number of times that the developing roller separates from the photosensitive drum.

[0036] According to the image forming apparatus of the sixteenth aspect, the amount of attached foreign matter can be appropriately calculated based on the number of times the developing roller comes into contact with the photosensitive drum and the number of times the developing roller separates from the photosensitive drum.

[0037] According to the seventeenth aspect of the image forming apparatus, when the calculated amount of foreign matter adhesion exceeds a predetermined threshold, the use of the drum cartridge is restricted, thereby making it possible to prevent the use of a drum cartridge in which an abnormality has occurred due to the adhesion of foreign matter.

[0038] According to the image forming apparatus of the 18th aspect, when the amount of foreign matter adhesion exceeds the first threshold, information encouraging the user to replace the drum cartridge is displayed on the display, thereby encouraging the user to replace the drum cartridge with severe foreign matter adhesion.

[0039] According to the image forming apparatus of the nineteenth aspect, when it is determined that the drum cartridge is abnormal based on the amount of foreign matter adhering thereto, a new drum can be ordered. [Brief description of the drawings]

[0040] [Figure 1] FIG. 1 illustrates an image forming system according to an embodiment. [Diagram 2] 1 is a schematic diagram illustrating an image forming apparatus according to an embodiment of the present invention; [Diagram 3] 2 is a schematic cross-sectional view showing a photoconductor drum and peripheral elements of the photoconductor drum according to the embodiment. FIG. [Figure 4] 2 is a diagram showing electrical connections between a control unit and other elements in the image forming apparatus according to the embodiment; [Diagram 5]5A and 5B are diagrams illustrating a contract process and a cancellation process executed in the image forming system according to the embodiment. [Figure 6] 6 is a diagram showing a flow of a drum check process executed by a control unit of the image forming apparatus; [Figure 7] FIG. 11 is a diagram showing a detailed flow of a drum information latch process. [Figure 8] 5 is a diagram showing the correspondence between types of drum cartridges and operation modes of a control unit. FIG. [Figure 9] FIG. 7 is a diagram showing details of the drum life check process S37 shown in FIG. 6. [Figure 10] 11 is a diagram showing the flow of a first periodic implementation process executed by a control unit. FIG. [Figure 11] 13 is a diagram showing the flow of a second periodic implementation process executed by the control unit. FIG. [Figure 12] 13 is a diagram showing the flow of a third periodic implementation process executed by the control unit. FIG. [Figure 13] 13 is a diagram showing the flow of a fourth periodic implementation process executed by the control unit. FIG. [Figure 14] FIG. 13 is a diagram showing the flow of a fifth periodic implementation process executed by the control unit. [Figure 15] FIG. 13 is a diagram showing the flow of a sixth periodic implementation process executed by the control unit. [Figure 16] FIG. 13 is a diagram showing the flow of a seventh periodic implementation process executed by the control unit. [Figure 17] FIG. 13 is a diagram showing the flow of a seventh periodic implementation process executed by the control unit. [Figure 18] FIG. 13 is a diagram showing the flow of an eighth periodic implementation process executed by the control unit. [Figure 19] FIG. 13 is a diagram showing the flow of an eighth periodic implementation process executed by the control unit. [Figure 20] FIG. 13 is a diagram showing the flow of an eighth periodic implementation process executed by the control unit. [Figure 21] 6 is a diagram showing a procedure of adhesion amount update processing executed by a control unit. FIG. [Figure 22] FIG. 13 is a schematic diagram showing a modified image forming apparatus. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0041] Hereinafter, an embodiment of the present disclosure will be described with reference to the accompanying drawings. Note that the components described in the embodiment are merely examples, and are not intended to limit the scope of the present disclosure. In the drawings, the dimensions and numbers of each part may be simplified as necessary for ease of understanding.

[0042] Figure 1 shows

[0043] <1. Embodiment> Fig. 1 is a diagram showing an image forming system 100 according to an embodiment. The image forming system 100 includes an image forming apparatus 1, a server 7, and a registration apparatus 8. The image forming apparatus 1 and the server 7 are connected to each other so as to be able to communicate with each other via the Internet. As shown in Fig. 1, the server 7 is capable of communicating with a plurality of image forming apparatuses 1 via the Internet. Furthermore, the server 7 and the registration apparatus 8 are connected to each other so as to be able to communicate with each other via the Internet.

[0044] In the image forming system 100, a contract is concluded between a user of the image forming device 1 and a supplier of the image forming device 1 or the supplies (toner cartridge 30 and drum cartridge 20 described later) used in the image forming device 1. In the contract, for example, a charge amount is set for the user to print a page using the supplies. Specifically, the charge amount can be appropriately set according to the number of printed pages, the amount of each color toner used, the print mode such as monochrome printing or color printing, the print resolution, or the size of the print paper. The charge amount may be, for example, a flat rate system in which a certain number of printed pages are charged for a certain period (for example, one month), or a pay-per-use system in which a certain amount of printed pages is charged. In addition, the charge amount may be a fixed amount up to a certain amount of printed pages, and an additional charge may be made for the amount of printed pages exceeding the certain amount. Hereinafter, a user who has concluded a contract with a supplier may be referred to as a "contract user," and a user who has not concluded a contract may be referred to as a "normal user."

[0045] The server 7 is a device for managing information related to contracted users, managing charges and payments, and providing various services to contracted users. Services provided to contracted users include, for example, the service of shipping supplies to contracted users. The server 7 has a control unit 71, a storage unit 73, and a communication interface 75. The control unit 71 is electrically connected to the storage unit 73 and the communication interface 75 by bus wiring.

[0046] The control unit 71 has a CPU 711 and a memory 713. The memory 713 is a storage medium capable of reading and writing information, specifically a flash ROM or EEPROM, and stores a program 715. The control unit 71 executes various processes by the CPU 711 operating in accordance with the program 715. The memory unit 73 is specifically a storage such as a hard disk drive. The memory unit 73 stores registration information 731. The registration information 731 specifically includes information on the contracted user, information on the image forming device 1 registered by the contracted user, payment information (credit card information, bank account information, etc.), etc.

[0047] The registration device 8 is an information terminal used to register various information in the server 7. Specifically, the registration device 8 is a mobile terminal such as a smartphone or tablet owned by a user who wishes to enter into a contract, a computer connected to the image forming apparatus 1 via a cable or the like, or an information terminal operated by a supplier or the like.

[0048] The registration device 8 has a control unit 81 and a network interface 83. The control unit 81 and the network interface are connected via a bus wiring or the like. The control unit 81 has a CPU 811 and a memory 813. The memory 813 is a storage medium capable of reading and writing information, specifically, a flash ROM or an EEPROM. The memory 831 stores a program 815. The CPU 811 operates according to the program 815, whereby the control unit 81 executes various processes. The program 815 includes application software for causing the control unit 81 to execute processes for transmitting and receiving each piece of information to and from the server 7.

[0049] <Configuration of Image Forming Apparatus> Fig. 2 is a schematic diagram showing the configuration of the image forming apparatus 1 of the embodiment. Fig. 3 is a schematic cross-sectional view showing the photoconductor drum 21 and peripheral elements of the photoconductor drum 21 of the embodiment. Fig. 4 is a diagram showing electrical connections between a control unit 51 and other elements in the image forming apparatus 1 of the embodiment.

[0050] As shown in FIG. 2, the image forming apparatus 1 includes a main body housing 10, a cover 11, a drum cartridge 20, four toner cartridges 30, four light source units (not shown), a transfer unit 40, a control unit 51, and a display 55.

[0051] The main body housing 10 is in the shape of a rectangular box. The drum cartridge 20, the four toner cartridges 30, the transfer unit 40, and the control unit 51 are housed in the main body housing 10. The drum cartridge 20, the four toner cartridges 30, and the transfer unit 40 are removable and replaceable with respect to the main body housing 10. The display 55 is located on the outer surface of the main body housing 10. The main body housing 10 has a frame that holds the drum cartridge 20.

[0052] 2, the cover 11 can rotate about a rotation axis 11a extending in a first direction between an open position indicated by a solid line and a closed position indicated by a two-dot chain line. When the cover 11 is disposed in the open position, the opening of the main body housing 10 is opened. When the cover 11 is disposed in the closed position, the opening of the main body housing 10 is covered by the cover 11. Opening and closing of the cover 11 is detected by an opening / closing sensor 12 electrically connected to the control unit 51.

[0053] The drum cartridge 20 has four slots SL. One toner cartridge 30 is removably mounted in each slot SL. The drum cartridge 20 holding the four toner cartridges 30 is mounted in the main body housing 10 as a process cartridge.

[0054] The drum cartridge 20 has four photosensitive drums 21. The photosensitive drums 21 are cylindrical members extending in a first direction and are rotatable about a drum axis (rotation axis) extending in the first direction. As shown in Fig. 3, the photosensitive drum 21 specifically has a cylindrical aluminum tube 211 extending in the first direction and a photosensitive layer 213 covering the outer periphery of the aluminum tube 211. The photosensitive layer 213 is made of a photosensitive material.

[0055] The drum cartridge 20 has a drum memory 22. The drum memory 22 is, for example, a flash ROM or an EEPROM. The drum memory 22 stores information about the drum cartridge 20 in which the drum memory 22 is attached.

[0056] The drum cartridge 20 includes four chargers 23. Each charger 23 charges the corresponding photoconductor drum 21. As shown in FIG. 3, the chargers 23 are so-called scorotron chargers including a charging wire 231 extending in a first direction and a grid 233. The charging wire 231 and the grid 233 are electrically connected to a voltage application circuit 15 provided in the main body housing 10. The voltage application circuit 15 applies a predetermined bias (voltage) to the charging wire 231 and the grid 233 under the control of the control unit 51. The voltage application circuit 15 includes, for example, a transformer.

[0057] When the charger 23 is used for a long period of time, for example, a toner component (e.g., silica) adheres to the charging wire 231, and the impedance of the charging wire 231 increases. When the impedance increases, the current flowing through the grid 233 decreases. For this reason, when the current of the grid 233 is controlled to be constant current, the voltage value of the charging wire 231 increases. When the voltage value of the charging wire 231 exceeds a predetermined value, an abnormal discharge occurs between the charging wire 231 and the grid 233, and a large amount of current flows. Note that an abnormal discharge may also occur between the charging wire 231 and the surface of the photosensitive drum, and a large amount of current may flow. When an abnormal discharge occurs, the photosensitive drum 21 cannot be uniformly charged, and image quality may deteriorate.

[0058] The image forming apparatus 1 includes a detector for detecting abnormal discharge. When the control unit 51 controls the voltage application circuit 15 to apply a predetermined bias to the charged wire 231 and the grid 233, if abnormal discharge occurs, an overcurrent occurs in the transformer provided in the voltage application circuit 15. The detector detects an overcurrent of a predetermined threshold or more that flows in the voltage application circuit 15. The control unit 51 is electrically connected to the detector, and detects abnormal discharge in the charger 23 based on an output from the detector. The control unit 51 is electrically connected to the charged wire 231 and the grid 233, and can read the voltage values ​​applied to the charged wire 231 and the grid 233.

[0059] The drum cartridge 20 includes four cleaning rollers 25. Each cleaning roller 25 cleans the outer surface of the corresponding photosensitive drum 25. More specifically, the cleaning roller 25 removes toner and paper powder remaining on the outer surface of the photosensitive drum 21. The cleaning roller 25 is an example of a cleaning member. The cleaning roller 25 has a cylindrical shape extending in a first direction. The cleaning roller 25 is rotatable about an axis extending in the first direction. The cleaning roller 25 contacts the outer surface of the photosensitive drum 21.

[0060] As shown in Fig. 3, the drum cartridge 20 includes an erase lamp 26. The erase lamp 26 discharges electricity from the outer surface of the photoconductor drum 21 by irradiating the outer surface of the photoconductor drum 21 with light. More specifically, an electric charge is generated in the photosensitive layer 27 of the photoconductor drum 21 by the illumination of the erase lamp 26, and the generated negative electric charge cancels out the positive electric charge on the surface of the photoconductor drum 21. This reduces the electric potential of the surface of the photoconductor drum 21. The on / off switching of the light irradiation by the erase lamp 26 is controlled by the control unit 51.

[0061] As shown in FIG. 2, the toner cartridge 30 includes a developing roller 31, a toner memory 32, and a casing 33. The developing roller 31 is a cylindrical member extending in a first direction. The developing roller 31 is rotatable about a developing axis extending in the first direction. The toner memory 32 is a storage medium from which information can be read and written, specifically, a flash ROM or an EEPROM. The toner memory 32 stores information about the toner cartridge 30 to which the toner memory 32 is attached. The casings 33 of the four toner cartridges 30 contain toner of different colors (for example, any one of cyan, magenta, yellow, and black).

[0062] The drum cartridge 20 with the toner cartridge 30 attached is attached to the main body housing 10 with the cover 11 in the open position. The drum cartridge 20 with the toner cartridge 30 attached passes through an opening of the main body housing 10 and is attached to a cartridge holder in the main body housing 10.

[0063] The four light source units are attached to the inner surface of the main body housing 10. When the drum cartridge 20 is attached to the main body housing 10 and the cover 11 is in the closed position, each light source unit faces the outer surface of the photosensitive drum 21. In addition, each light source unit can irradiate light onto the outer circumferential surface of the photosensitive drum 21. The light source is a laser or an LED (light emitting diode).

[0064] As shown in Fig. 2, the image forming apparatus 1 includes a temperature sensor 17 and a humidity sensor 18. As shown in Fig. 4, the temperature sensor 17 and the humidity sensor 18 are electrically connected to the control unit 51. The temperature sensor 17 detects the temperature inside the main body housing 10 and outputs the detected temperature to the control unit 51. The humidity sensor 18 detects the humidity inside the main body housing 10 and outputs the detected humidity to the control unit 51. The temperature sensor 17 and the humidity sensor 18 are installed, for example, inside the main body housing 10.

[0065] The transfer unit 40 has a transfer belt 41, a drive roller 43, a driven roller 45, and four transfer rollers 47. The transfer belt 41 is annular (endless belt). The outer peripheral surface of the photosensitive drum 21 can come into contact with the outer peripheral surface of the transfer belt 41. The transfer belt 41 is stretched between the drive roller 43 and the driven roller 45. The control unit 51 drives the drive roller 43 to rotate the transfer belt 41. The driven roller 45 rotates in accordance with the movement of the transfer belt 41 driven by the drive roller 43.

[0066] The four transfer rollers 47 are located inside the transfer belt 41. The transfer rollers 47 are cylindrical and extend in a first direction, and are rotatable about a rotation axis that extends in the first direction. The outer surface of the transfer rollers 47 is made of, for example, conductive rubber. The transfer rollers 47 are electrically connected to the voltage application circuit 15, and a transfer bias (voltage) is applied to them when necessary.

[0067] The transfer roller 47 is located below the photoconductor drum 21. The transfer belt 41 is sandwiched between the photoconductor drum 21 and the transfer roller 47. When a transfer bias is applied to the outer surface of the transfer roller 47, the toner adhering to the outer surface of the photoconductor drum 21 moves toward the transfer belt 41. As a result, the toner moves to the printing paper on the transfer belt 41 and is transferred to the printing paper.

[0068] When performing printing processing in the image forming apparatus 1, the charger 23 uniformly charges the entire surface of the photoconductor drum 21. Then, the light source unit irradiates the photoconductor drum 21 with laser light or LED light corresponding to the image to be printed. Then, the developing roller 31 adheres to the exposed surface of the photoconductor drum 21. Furthermore, the transfer unit 40 transfers the toner adhered to the photoconductor drum 21 to the printing paper. The toner transferred to the printing paper is heated by a thermal fixing unit (not shown) and fixed to the printing paper. Furthermore, the toner remaining on the photoconductor drum 21 is removed from the photoconductor drum 21 by the cleaning roller 25.

[0069] 4, image forming apparatus 1 has control unit 51, operation unit 53, display 55, and communication interface 57. Control unit 51 has CPU 511 and main memory 513. Main memory 513 stores program 515. CPU 511 operates according to program 515, causing control unit 51 to execute various processes. Note that control unit 51 may include a dedicated circuit such as an ASIC (application specific semiconductor integrated circuit).

[0070] The control unit 51 is set to either the "contract mode" or the "normal mode" and executes processing according to the set operation mode. As will be described later, the operation mode of the image forming device 1 is set to the contract mode or the normal mode based on a setting command sent from the server 7. The processing contents according to the contract mode and the normal mode are defined in the program 515.

[0071] The operation unit 53 is a button that accepts user operations. The display 55 displays images showing various information. The display 55 may function as the operation unit 53 by being configured as a so-called touch panel.

[0072] The communication interface 57 is a device that enables the control unit 51 to communicate with the server 7 (communication device) via a network.

[0073] 4, when the drum cartridge 20 and the four toner cartridges 30 are attached to the main body housing 10, the drum memory 22 and the four toner memories 32 are electrically connected to the control unit 51. This enables the control unit 51 to communicate data with the drum memory 22 and each toner memory 32.

[0074] The drum memory 22 stores a drum ID, drum life information, drum type information, drum history information, an order flag, threshold information, and adhesion amount information. The drum ID is identification information for identifying each drum cartridge 20, and is specifically a serial number. The drum life information includes, for example, the cumulative number of rotations of the photosensitive drum 21 and the cumulative number of printed sheets using the photosensitive drum 21. The cumulative number of rotations of the photosensitive drum 21 is the number of rotations calculated by incrementing or decrementing each time printing (job) is performed in the drum cartridge 20 identified by the drum identification information. The cumulative number of printed sheets using the photosensitive drum 21 is the number of printed sheets calculated by incrementing or decrementing each time printing (job) is performed in the drum cartridge 20 identified by the drum identification information.

[0075] The drum type information is information that indicates the type of drum cartridge 20. Specifically, the drum type information is information that indicates either the "normal type" or the "contract type". In the following, a drum cartridge 20 whose drum type information indicates the "normal type" may be referred to as a "normal drum cartridge 20", and a drum cartridge 20 whose drum type information indicates the "contract type" may be referred to as a "contract drum cartridge 20".

[0076] The contract drum cartridge 20 may be less expensive than the normal drum cartridge 20. The contract drum cartridge 20 may also be less durable than the normal drum cartridge 20. Specifically, the price or durability of the drum cartridge 20 can be changed by changing at least one of the material of the photosensitive layer 213, the thickness of the photosensitive layer 213, and the material of the cleaning roller 25. The contract drum cartridge 20 may also be more expensive than the normal drum cartridge 20. The durability of the contract drum cartridge 20 may also be higher than that of the normal drum cartridge 20.

[0077] The drum history information is information indicating that an abnormality has been detected in the drum cartridge 20. When the control unit 51 detects an abnormality in the drum cartridge 20, it records the abnormality in the drum memory 22 as drum history information. The drum history information specifically includes discharge history information indicating that an abnormality has been detected in the charger 23 of the drum cartridge 20. The discharge history information specifically includes the number of pre-discharge detections and the number of discharge detections.

[0078] Note that, when the number of abnormal discharges occurring in the charger 23 within a predetermined time period exceeds a threshold value representing a discharge abnormality, the control unit 51 may count the number of occurrences as a detection of a discharge abnormality. Specifically, the number of occurrences of abnormal discharge may be the number of times that the current value of the charging wire 231 becomes equal to or greater than the threshold value representing an abnormal discharge. For example, when abnormal discharge (overcurrent) occurs three or more times within 50 msec, the control unit 51 may count it as one occurrence as a detection of a discharge abnormality.

[0079] The pre-discharge detection count is the number of pre-discharge abnormalities detected in the discharge check process. The pre-discharge abnormality refers to a state in which abnormal discharge is likely to occur. Specifically, when a voltage value of the charging wire 231 becomes equal to or greater than a predetermined threshold value when a predetermined bias is applied to the charger 23, the control unit 51 determines that a pre-discharge abnormality has been detected and starts counting.

[0080] The ordered flag is information indicating whether or not an order for a new drum cartridge 20 has been placed. In the image forming apparatus 1, before the remaining life of the drum cartridge 20 runs out or when an abnormality is detected in the drum cartridge 20, the control unit 51 executes a transmission process to transmit order information for ordering a new drum cartridge 20 to the server 7. When the control unit 51 executes the transmission process, it updates the ordered flag in the drum memory 22 attached to the main body housing 10, assuming that an order for a new drum cartridge 20 has been placed. Updating the ordered flag makes it possible to prevent a new drum cartridge 20 from being ordered twice.

[0081] The threshold information is information that indicates thresholds used in various determination processes that the control unit 51 executes for the drum cartridge 20. The threshold information includes, for example, a threshold for determining whether the drum cartridge 20 has a remaining life, a threshold for determining an abnormality in the drum cartridge 20, and the like.

[0082] The drum memory 22 may store information such as compatible models for the drum cartridge 20, specifications for the drum cartridge 20, information indicating whether the cartridge is new or not, information indicating whether the cartridge is genuine or not, and error history.

[0083] As shown in FIG. 4, the toner memory 32 stores a toner ID, toner life information, and toner type information. The toner ID is identification information for identifying each toner cartridge 30, and specifically, is a serial number. The toner life information is at least one of the cumulative number of rotations of the developing roller 31, the cumulative number of printed sheets using the developing roller 31, and the cumulative number of dots. The cumulative number of rotations of the developing roller 31 is the number of rotations calculated by incrementing or decrementing each time printing (job) is performed in one toner cartridge 30 identified by the toner ID. The cumulative number of printed sheets using the developing roller 31 is the number of printed sheets calculated by incrementing or decrementing each time printing (job) is performed in one toner cartridge 30 identified by the toner ID. The cumulative number of dots using the developing roller 31 is the number of dots calculated by incrementing or decrementing each time printing (job) is performed in one toner cartridge 30 identified by the toner identification information. The toner memory 32 may store information indicating the remaining amount of toner contained in the casing 33 instead of the cumulative dot number.

[0084] The toner type information is information that indicates the type of the toner cartridge 30, and specifically, is information that indicates either a "contract type" or a "normal type". Hereinafter, a toner cartridge 30 whose toner type information is "contract type" may be referred to as a "contract type toner cartridge 30", and a toner cartridge 30 whose toner type information is "normal type" may be referred to as a "normal type toner cartridge 30". As will be described later, the toner type information is information for controlling the use of the toner cartridge 30 in the image forming apparatus 1.

[0085] The toner memory 32 may store information such as the model of the image forming apparatus 1 compatible with the toner cartridge 30, the specifications of the toner cartridge 30, information indicating whether it is a new product or not, information indicating whether it is a genuine product or not, and the like.

[0086] The control unit 51 permits the use of the normal toner cartridge 30 regardless of the normal mode or the contract mode. In other words, the normal toner cartridge 30 can be printed regardless of whether the control unit 51 is set to the normal mode or the contract mode. In contrast, the control unit 51 prohibits the print process of the contract toner cartridge 30 when the normal mode is set, and permits the print process when the contract mode is set. Note that in the normal mode, it is not essential for the control unit 51 to prohibit the use of the contract toner cartridge 30, and the contract toner cartridge 30 may be allowed to be used under certain restrictions. For example, the control unit 51 may display on the display 55 a screen encouraging replacement or a warning screen indicating a violation of the regulations.

[0087] The main body memory 513 stores drum information and toner information. The drum information is information about the drum cartridge 20 attached to the main body housing 10, and specifically includes a drum ID, drum life information, drum type information, drum history information, an order completion flag, threshold information, and adhesion amount information. The toner information is information about each toner cartridge 30 attached to the main body housing 10, and specifically includes a toner ID, toner type information, and toner life information.

[0088] The control unit 51 stores various pieces of information read from the drum memory 22 in the main body memory 513 as drum information. The control unit 51 also stores various pieces of information read from each toner memory 32 in the main body memory 513 as toner information. The control unit 51 also updates the drum information and toner information as necessary. The control unit 51 also updates various pieces of information stored in the corresponding drum memory 22 or each toner memory 32 based on the updated drum information or toner information.

[0089] As shown in FIG. 4, the main body housing 10 includes a drive unit 19. The drive unit 19 moves the developing roller 31 between a contact position (position indicated by a solid line in FIG. 3) where the developing roller 31 is in contact with the photosensitive drum 21 and a spaced position (position indicated by a dashed line in FIG. 3) where the developing roller 31 is spaced from the photosensitive drum 21. For example, when monochrome printing is performed in the image forming apparatus 1, the control unit 51 controls the drive unit 19 to move the black developing roller 31 to the contact position and the cyan, magenta, and yellow developing rollers 31 to the spaced positions. This allows black toner to be supplied only to the black photosensitive drum 21. Note that the black developing roller 31 may be disposed at the spaced position.

[0090] <Calculating the amount of foreign matter attached> Foreign matter may adhere to the surface of the photoconductor drum 21. The foreign matter may include, for example, an external additive of the toner. Specifically, the toner particles are composed of toner base particles and an external additive. The toner base particles may have, for example, a spherical shape. The toner base particles may include, for example, a binder resin, a colorant, a release agent (wax), and a charge control agent. The external additive may be, for example, silica. Silica adheres to the surface of the toner base particles and is added to control the chargeability, fluidity, or antiblocking property of the toner. In the following description, a case where the foreign matter is silica of the toner. Note that silica is an example of a foreign matter, and the foreign matter is not limited to silica.

[0091] If a large amount of silica in the toner adheres to the surface of the photoconductor drum 21 as foreign matter, the printing quality may be significantly reduced due to defects in the formation of a latent image on the photoconductor drum 21 and defects in the transfer of toner. Therefore, in the image forming apparatus 1, the occurrence of an abnormality in the drum cartridge 20 is predicted by calculating the amount of adhesion of such foreign matter.

[0092] When the developing roller 31 is in contact with the photosensitive drum 21, the developing roller 31 may apply pressure to the photosensitive drum 21, causing the developing roller 31 to rub the silica on the developing roller 31 against the photosensitive drum 21. More specifically, when the developing roller 31 moves from a separated position to a contact position with respect to the photosensitive drum 21 (when pressed), when the developing roller 31 moves from a contact position to a separated position with respect to the photosensitive drum 21 (when separated), and when the developing roller 31 rotates with a peripheral speed difference with respect to the photosensitive drum 21 (when rotating normally), the silica on the developing roller 31 may adhere to the photosensitive drum 21. The pressure applied from the developing roller 31 to the photosensitive drum 21 becomes weaker in the order of when pressed, when separated, and when rotating normally. Therefore, the amount of silica adhering to the photosensitive drum 21 from the photosensitive drum 31 and the adhesive force become smaller in the order of when pressed, when separated, and when rotating normally.

[0093] <Silica adhesion caused by cleaning roller 25> The cleaning roller 25, which comes into contact with the photosensitive drum 21, is basically capable of removing silica from the photosensitive drum 21. However, under certain conditions, the cleaning roller 25 can act in a direction that promotes adhesion of silica to the photosensitive drum 21. Specifically, when the developing roller 31 is separated from the photosensitive drum 21 and the cleaning roller 25 and the photosensitive drum 21 rotate with a difference in peripheral speed, silica is likely to move from the cleaning roller 25 to the photosensitive drum 21.

[0094] When the developing roller 31 is in pressure contact with the photosensitive drum 21, the cleaning roller 25 uses the silica supplied from the developing roller 31 to the photosensitive drum 21 as a cleanser to scrape off the photosensitive layer 213 of the photosensitive drum 21. In some cases, the cleaning roller 25 removes only the silica that has adhered to the surface of the photosensitive drum 21 as foreign matter. For this reason, when the developing roller 31 is in pressure contact with the photosensitive drum 21, the cleaning roller 25 can act in a direction to reduce the silica that adheres to the photosensitive drum 21.

[0095] The control unit 51 calculates the amount of silica adhering to the photoconductor drum 21 based on the following formulas (1) and (2).

[0096] Y = ΣΔY (1) ΔY=(A+B)×ΔX+(C×Tr+D×Tp)...(2)

[0097] In formula (1), "Y" is the amount of silica adhering to the photoconductor drum 21. Also, "ΔY" is the increased amount of silica adhering to the photoconductor drum 21. As shown in formula (1), the control unit 51 calculates the amount of adhesion Y by accumulating the increased amount ΔY.

[0098] In formula (2), "A" is a parameter (first parameter) indicating how easily foreign matter adheres from the developing roller 31 to the photoconductor drum 21. "B" is a parameter (second parameter) indicating how easily silica adheres from the cleaning roller 25 to the photoconductor drum 21. ΔX is the rotation speed of the photoconductor drum 21.

[0099] In formula (2), "Tr" is the number of times that the developing roller 31 moves from the separated position to the contact position. In other words, "Tr" is the number of times (number of times of pressure contact) that the developing roller 31 transitions from a state in which it is separated from the photosensitive drum 21 to a state in which it is in pressure contact with the photosensitive drum 21. "Tp" is the number of times that the developing roller 31 moves from the contact position to the separated position. In other words, "Tp" is the number of times that the developing roller 31 transitions from a state in which it is in pressure contact with the photosensitive drum 21 to a state in which it is separated from the photosensitive drum 21.

[0100] In formula (2), "C" is a parameter indicating how easily silica adheres from the developing roller 31 to the photoconductor drum 21 when the developing roller 31 moves from the separate position to the contact position. "D" is a parameter indicating how easily foreign matter adheres from the developing roller 31 to the photoconductor drum 21 when the developing roller 31 moves from the contact position to the separated position.

[0101] The values ​​of parameters A and B change depending on the operating conditions and environment of image forming apparatus 1. Parameters C and D may also be changed depending on the operating conditions and environment of image forming apparatus 1. Controller 51 calculates the increase amount ΔY at an appropriate timing, such as when parameters A and B change. Controller 51 then calculates the adhesion amount Y by accumulating the calculated increase amount ΔY.

[0102] As shown in the formula (2), the increase amount ΔY includes a value obtained by multiplying the sum of the parameter A and the parameter B by the rotation speed ΔX. That is, the control unit 51 calculates the increase amount according to the rotation speed of the photoconductor drum 21.

[0103] As shown in formula (2), the increase amount ΔY includes a value obtained by multiplying parameter C by the number of times of contact Tr and a value obtained by multiplying parameter D by the number of times of separation Tp. That is, the control unit 51 calculates the adhesion amount Y based on the number of times that the developing roller 31 moves from the separated position to the contact position (number of times of contact Tr), the number of times that the developing roller 31 moves from the contact position to the separated position (number of times of separation Tp), and parameters C and D. Note that the control unit 51 may calculate the adhesion amount Y using only one of the number of times of contact Tr or the number of times of separation Tp.

[0104] The ease with which silica adheres to the photoconductor drum 21 may vary depending on the temperature and humidity around the photoconductor drum 21. For this reason, the values ​​of parameters A, B, C, and D may be varied depending on the temperature output by the temperature sensor 17 and the humidity output by the humidity sensor 18.

[0105] The ease with which silica adheres to the photoconductor drum 21 may vary depending on whether the erase lamp 26 is on or off. Therefore, the values ​​of the parameters A, B, C, and D may be varied depending on whether the erase lamp 26 is on or off.

[0106] The greater the voltage that the charger 23 applies to the photoconductor drum 21, the more easily silica adheres to the photoconductor drum 21. For this reason, the parameters A, B, C, and D may be parameters whose increment ΔY increases as the voltage that the charger 23 applies to the photoconductor drum 21 increases.

[0107] When the toner contained in the casing 33 deteriorates over time, silica may easily adhere to the photoconductor drum 21. In the image forming apparatus 1, the cumulative number of rotations of the developing roller 31 increases as the printing process is executed. Therefore, the deterioration of the toner over time may have a positive correlation with the cumulative number of rotations of the developing roller 31. Therefore, the values ​​of the parameters A, B, C, and D may be varied according to the cumulative number of rotations of the developing roller 31. Specifically, the values ​​of the parameters A, B, C, and D may be increased as the cumulative number of rotations of the developing roller 31 increases. This allows the amount of silica adhering to the photoconductor drum 21 to be appropriately calculated according to the degree of deterioration of the toner.

[0108] <Example of image formation system operation> FIG. 5 is a diagram showing a contract process S1 and a cancellation process S2 executed in the image forming system 100 of the embodiment. The contract process S1 is a process performed when a normal user concludes a contract with a supplier. The contract process S1 includes a process of changing the operation mode of the image forming device 1 of the contracted user from the normal mode to the contracted mode. The cancellation process S2 is a process performed when the contracted user cancels the contract. The cancellation process S2 includes a process of changing the operation mode of the image forming device 1 of the contracted user from the contracted mode to the normal mode. The contract process S1 and the cancellation process S2 will be described in order below.

[0109] <Contract Processing> In the contract process S1, first, the registration device 8 transmits a contract request Rq1 to the server 7 (contract request transmission process S11). The contract request Rq1 may include information about the user who desires to enter into a contract (including the user's name, address, etc.) and information about the contract, such as the amount charged. The contract request Rq1 may also include information about payment and device information (device ID) for identifying the image forming device 1 used by the user. It is not essential that the registration device 8 performs the contract request transmission process S11. For example, the image forming device 1 may transmit the contract request Rq1 to the server 7 by the user performing a predetermined operation on the image forming device 1.

[0110] The server 7 transmits a change command Rs1 to the image forming apparatus 1 for which a contract has been requested based on the received contract request Rq1 (change command transmission process S12). The change command Rs1 is a command to the control unit 51 included in the target image forming apparatus 1, and is a command to set the operation mode of the control unit 51 to the contract mode. Upon receiving the change command Rs1, the control unit 51 sets the operation mode to the contract mode (operation mode setting process S13).

[0111] <Cancellation process> In the cancellation process S2, first, the registration device 8 transmits a cancellation request Rq2 to the server 7 (cancellation request transmission process S21). The cancellation request Rq2 may include information about the user who wishes to cancel. It is not essential that the registration device 8 performs the cancellation request transmission process S21. For example, the image forming device 1 may transmit the cancellation request Rq2 to the server 7 by a user performing a predetermined operation on the image forming device 1.

[0112] Based on the received cancellation request Rq2, the server 7 transmits a change command Rs2 to the image forming apparatus 1 for which cancellation has been requested (change command transmission process S22). The change command Rs2 is a command to the control unit 51 included in the target image forming apparatus 1, and is a command to set the operation mode of the control unit 51 to the normal mode. Upon receiving the change command Rs2, the control unit 51 sets the operation mode to the normal mode (operation mode setting process S23).

[0113] 6 is a diagram showing the flow of the drum check process executed by the control unit 51 of the image forming apparatus 1. The drum check process is a process that is executed when the drum cartridge 20 is replaced.

[0114] When the control unit 51 starts the drum check process, it determines whether the drum cartridge 20 has been replaced (replacement determination process S31). In the replacement determination process S31, when the power supply of the image forming apparatus 1 is switched from ON to OFF, or when the open / close sensor 12 detects that the cover 11 has moved from the open position to the closed position, the control unit 51 compares the drum ID of the drum cartridge 20 with the drum ID previously stored in the main body memory 513. When the drum IDs match, the control unit 51 determines that the drum cartridge 20 has not been replaced. When the drum IDs do not match, the control unit 51 determines that the drum cartridge 20 has been replaced.

[0115] When the control unit 51 determines that the drum cartridge 20 has been replaced by the replacement determination process S31 (Yes), the control unit 51 executes a drum information latch process S32. In the drum information latch process S32, the control unit 51 reads out various pieces of information stored in the drum memory 22 and writes them to the main body memory 513.

[0116] Fig. 7 is a diagram showing a detailed flow of the drum information latch process S32. As shown in Fig. 7, the drum information latch process S32 includes reading and writing drum life information (read and write process S41), reading and writing drum type information (read and write process S42), reading and writing drum history information (read and write process S43), reading and writing an order completion flag (read and write process S44), and reading and writing adhesion amount information (read and write process S45).

[0117] In a read / write process S41, the control unit 51 stores the cumulative number of printed sheets and the cumulative number of drum rotations represented by the drum life information read from the drum memory 22 in the main body memory 513 as drum information. In a read / write process S42, the control unit 51 stores the drum type information read from the drum memory 22 in the main body memory 513 as drum information. In a read / write process S43, the control unit 51 stores the pre-discharge detection count and the discharge detection count represented by the drum history information read from the drum memory 22 in the main body memory 513 as drum information. In a read / write process S45, the control unit 51 reads the adhesion amount information from the drum memory 22 and stores it in the main body memory 513 as drum information. The adhesion amount information is information representing the adhesion amount Y of silica to the photosensitive drum 21.

[0118] 6, after executing the drum information latch process S32, the control unit 51 determines whether the drum cartridge 20 is usable (determination process S33). Depending on the result of the determination process S33, the control unit 51 executes an error process S36 or a drum life check process S37.

[0119] Fig. 8 is a diagram showing the correspondence between the types of drum cartridges 20 and the operation modes of the control unit 51. As shown in Fig. 8, when the operation mode of the control unit 51 is the normal mode, the control unit 51 permits the use of normal drum cartridges 20 but restricts the use of contract drum cartridges 20. When the operation mode of the control unit 51 is the contract mode, the control unit 51 permits the use of both normal drum cartridges 20 and contract drum cartridges 20.

[0120] Returning to Fig. 6, when the control unit 51 determines in the determination process S33 that the use of the drum cartridge 20 cannot be permitted (No), it executes the error process S36. In the error process S36, the control unit 51 may store an unusable flag indicating that the use of the drum cartridge 20 is prohibited in the main body memory 513. In the error process S36, the control unit 51 may also cause the display 55 to display information requesting replacement with a normal drum cartridge 20. After executing the error process S36, the control unit 51 ends the drum check process.

[0121] When the control unit 51 determines in the determination process S33 that the use of the drum cartridge 20 is permitted (Yes), the control unit 51 executes a drum life check process S37. In the drum life check process S37, the control unit 51 checks the drum history information, drum life information, and adhesion amount information stored in the main body memory 513 in the drum information latch process S32.

[0122] <Drum life check process> 9 is a diagram showing details of the drum life check process S37 shown in FIG. 6. When the control unit 51 starts the drum life check process S37, it judges whether the drum cartridge 20 is in a state where it should be replaced (hereinafter referred to as a "replacement required state") based on the drum history information stored in the main body memory 513 (judgment process S51). In the judgment process S51, the control unit 51 judges whether the "pre-discharge detection count" represented by the drum history information exceeds a threshold value Th_1e indicating a replacement required state, and judges whether the "discharge detection count" represented by the drum history information exceeds a threshold value Th_2e indicating a replacement required state. In the judgment process S51, it is sufficient for the control unit 51 to at least judge whether the "discharge detection count" represented by the drum history information exceeds a threshold value Th_2e indicating a replacement required state. Alternatively, in the judgment process S51, the control unit 51 may determine whether the "number of pre-discharge detections" represented by the drum history information exceeds a threshold value Th_1e indicating a state requiring replacement, or whether the "number of discharge detections" represented by the drum history information exceeds a threshold value Th_2e indicating a state requiring replacement.

[0123] When the control unit 51 performs a judgment using a threshold value for certain numerical data, the control unit 51 may judge whether the numerical data is equal to or greater than the threshold value. For example, in the judgment process S51, the control unit 51 may judge whether the number of pre-discharge detections represented by the drum history information is equal to or greater than a predetermined threshold value. Also, in the judgment process S51, the control unit 51 may judge whether the number of discharge detections represented by the drum history information is equal to or greater than a predetermined threshold value.

[0124] When the control unit 51 determines in the determination process S51 that the pre-discharge detection count exceeds the threshold value Th_1e or when the control unit 51 determines that the discharge detection count exceeds the threshold value Th_2e (Yes in the determination process S51), the control unit 51 determines that the drum cartridge 20 needs to be replaced, and executes the display process S54 described later. Note that the control unit 51 may further measure the voltage value of the charged wire 231 after determining in the determination process S51 that the discharge detection count exceeds the threshold value Th_2e. Then, when the control unit 51 determines that the measured voltage value of the charged wire 231 is lower than a predetermined voltage value (or that the measured voltage value of the charged wire 231 is an abnormal value), the control unit 51 may execute the display process S54. When the control unit 51 determines in the determination process S51 that the pre-discharge detection count does not exceed the threshold value Th_1e and that the discharge detection count does not exceed the threshold value Th_2e (No in the determination process S51), the control unit 51 executes the determination process S52.

[0125] In the determination process S52, the control unit 51 determines whether the drum cartridge 20 needs to be replaced based on the drum life information stored in the main body memory 513. In the determination process S52, the control unit 51 determines whether the "cumulative number of printed sheets" in the drum life information exceeds a threshold value Th_3e indicating a replacement-needed state, and determines whether the "cumulative drum rotation count" in the drum life information exceeds a threshold value Th_4e indicating a replacement-needed state. If the control unit 51 determines in the determination process S52 that the cumulative number of printed sheets exceeds the threshold value Th_3e, or if the control unit 51 determines that the cumulative drum rotation count exceeds the threshold value Th_4e (Yes in the determination process S52), the control unit 51 executes the display process S54. If the control unit 51 determines in the determination process S52 that the cumulative number of printed sheets does not exceed the threshold value Th_3e and that the cumulative drum rotation count does not exceed the threshold value Th_4e (No in the determination process S52), the control unit 51 executes the determination process S53.

[0126] In a determination process S53, the control unit 51 determines whether the drum cartridge 20 needs to be replaced based on the adhesion amount information stored in the main body memory 513. In the determination process S53, the control unit 51 determines whether the "adhesion amount Y" of the adhesion amount information exceeds a threshold value Th_5e (first threshold value) indicating a replacement required state. When the control unit 51 determines in the determination process S53 that the adhesion amount Y exceeds the threshold value Th_5e (Yes), the control unit 51 executes a display process S54.

[0127] In display processing S54, the control unit 51 causes the display 55 to display an image (for example, an image including the characters "Replace Drum") that prompts the user to replace the drum cartridge 20. After executing the display processing S54, the control unit 51 ends the drum life check processing.

[0128] The display process S54 is an example of a usage restriction process that restricts the use of the drum cartridge 20. Note that, when the control unit 51 determines in the determination process S53 that the amount Y of silica adhesion exceeds the threshold value Th_5e, the control unit 51 may prohibit the use of the drum cartridge 20 in the image forming apparatus 1.

[0129] When the control unit 51 determines in the determination process S53 that the adhesion amount Y does not exceed the threshold value Th_5e (No), the control unit 51 determines whether the drum cartridge 20 is in an order-required state based on the drum life information (determination process S55). The order-required state refers to a state before the drum cartridge 20 becomes in a state requiring replacement, and a state in which a new drum cartridge 20 should be ordered. The order-required state is specifically a state in which the remaining life is short, or a state in which a problem such as a breakdown is likely to occur.

[0130] In the determination process S55, the control unit 51 determines whether the "cumulative number of printed sheets" of the drum life information exceeds a predetermined threshold Th_3 indicating an order required state, and whether the "cumulative number of drum rotations" of the drum life information exceeds a threshold Th_4 indicating an order required state. If the control unit 51 determines that the cumulative number of printed sheets does not exceed the threshold Th_3 and that the cumulative number of drum rotations does not exceed the threshold Th_4 (No in the determination process S55), the control unit 51 executes the determination process S56. If the control unit 51 determines that the cumulative number of printed sheets exceeds the threshold Th_3 or that the cumulative number of drum rotations exceeds the threshold Th_4 (Yes in the determination process S55), the control unit 51 executes the display process S57 described later.

[0131] In the determination process S56, the control unit 51 determines whether the drum cartridge 20 is in an order-required state based on the adhesion amount information. Specifically, the control unit 51 determines whether the "adhesion amount Y" of the adhesion amount information exceeds a threshold value Th_5 indicating an order-required state. If the control unit 51 determines that the adhesion amount Y exceeds the threshold value Th_5 (Yes in the determination process S56), the control unit 51 executes a display process S57. If the control unit 51 determines that the adhesion amount Y does not exceed the threshold value Th_5 (No in the determination process S56), the control unit 51 ends the drum life check process.

[0132] In the display process S57, the control unit 51 causes the display 55 to display a screen indicating that the drum cartridge 20 is in an order-required state (for example, an image including the text "Drum End Soon"). After executing the display process S57, the control unit 51 determines whether the drum type information of the drum cartridge 20 attached to the main body housing 10 is a contract type (determination process S571). When the control unit 51 determines that the drum type information is not a contract type (No in the determination process S571), it ends the drum life check process.

[0133] When the control unit 51 determines that the drum type information is a contract type (Yes in the determination process S571), it determines whether a new contract drum cartridge 20 has not been ordered. Specifically, the control unit 51 makes this determination based on the order flag stored in the main body memory 513 (order determination process S58). The order flag is information indicating whether an order has been placed, and is information stored in the main body memory 513 as drum information. When the control unit 51 determines that an order has not been placed through the order determination process S58, it executes the order information transmission process S59. When the control unit 51 determines that an order has been placed through the order determination process S58, it ends the drum life check process.

[0134] The order information transmission process S59 is a process in which the control unit 51 transmits order information for ordering a new contract drum cartridge 20 to the server 7. The order information includes, for example, information indicating that a new contract drum cartridge 20 is requested and device information of the image forming apparatus 1. As shown in FIG. 5, when the server 7 receives the order information, it transmits the order information to the server 9 of the shipping company (order processing S751). The order information specifically includes information such as the name and address of the contract user corresponding to the order information. The shipping company ships the contract drum cartridge 20 to the contract user based on the order information (shipping processing S752). This allows the contract user to receive the contract drum cartridge 20, so that when the drum cartridge 20 attached to the main body housing 10 needs to be replaced, it can be replaced with the contract drum cartridge 20.

[0135] The order information transmission process S59 may include an approval determination process in which the control unit 51 determines whether approval to transmit the order information has been received. Specifically, the control unit 51 may request the user to input approval by displaying an image requesting approval on the display 55. Then, when the control unit 51 receives an input of approval from the user, it may determine that approval has been received and transmit the order information. This makes it possible to prevent the order information from being automatically transmitted to the server 7 without the user's approval.

[0136] 9, after executing the order information transmission process S59, the control unit 51 executes the flag process S591. The flag process S591 is a process for saving an order completion flag in the main body memory 513 and the drum memory 22. After executing the flag process S591, the control unit 51 ends the drum life check process.

[0137] In the example shown in FIG. 9, the control unit 51 of the image forming apparatus 1 determines whether the drum cartridge 20 is in an order-required state by executing the determination process S55 or the determination process S56. Then, when the control unit 51 determines that the drum cartridge 20 is in an order-required state, a new drum cartridge 20 is ordered from the server 7. However, the server 7 may determine whether to order a new drum cartridge 20 by executing the determination process S55 or the determination process S56. For example, the image forming apparatus 1 may transmit drum life information or adhesion amount information to the server 7. Then, the server 7 may determine whether to order a new drum cartridge 20 by performing a process of comparing the drum life information with threshold values ​​Th_3 and Th_4 (processing corresponding to the determination process S55) or a process of comparing the adhesion amount information with a threshold value Th_5 (processing corresponding to the determination process S56).

[0138] 6, after executing the drum life check process S37, the control unit 51 executes the operation request waiting process S38. The operation request waiting process S38 is a process for putting the image forming apparatus 1 into a "Ready" (waiting for an operation request) state. That is, the control unit 51 puts the image forming apparatus 1 into a print request waiting state and makes the image forming apparatus 1 stand by.

[0139] 10 to 20, image forming apparatus 1 executes first to eighth periodic execution processes. The first to eighth periodic execution processes are executed by control unit 51 periodically or whenever a predetermined event occurs. The first to eighth periodic execution processes will be described below in order.

[0140] <First periodic implementation process> 10 is a diagram showing the flow of the first periodic execution process executed by the control unit 51. The first periodic execution process is a process in which the control unit 51 updates the drum life information stored in the drum memory 22 based on the drum life information stored in the main body memory 513. When the control unit 51 starts the first periodic execution process, it determines whether the cumulative number of printed sheets has increased from the drum life information stored in the main body memory 513 (determination process S61). When the control unit 51 determines that the cumulative number of printed sheets has increased (Yes in the determination process S61), it writes the cumulative number of printed sheets stored in the main body memory 513 to the drum memory 22 (write process S62).

[0141] After executing the determination process S61, the control unit 51 determines whether the cumulative drum rotation number has increased from the drum life information stored in the main body memory 513 (determination process S63). When the control unit 51 determines that the cumulative drum rotation number has increased (Yes in the determination process S63), it writes the cumulative drum rotation number stored in the main body memory 513 to the drum memory 22 (write process S64). After executing the determination process S63, the control unit 51 ends the first periodic implementation process.

[0142] <Second regular implementation process> FIG. 11 is a diagram showing the flow of the second periodic implementation process executed by the control unit 51. The second periodic process is a process for updating the temperature Tmep_now and humidity Hum_now stored in the main body memory 513. The temperature Temp_now represents the current temperature inside the main body housing 10. The humidity Hum_now represents the current humidity inside the main body housing 10. When the control unit 51 starts the second periodic implementation process, it updates the temperature Temp_now stored in the main body memory 513 based on the output of the temperature sensor 17 (temperature update process S65). After executing the temperature update process S65, the control unit 51 also updates the humidity Hum_now (humidity update process S66). After executing the humidity update process S66, the control unit 51 ends the second periodic update process.

[0143] <Third regular implementation process> 12 is a diagram showing the flow of the third regular execution process executed by the control unit 51. The third regular execution process is a process for updating the grid bias value GBias_now stored in the main body memory 513. The grid bias value GBias_now is information representing the magnitude of the voltage currently applied by the charger 23 to the photoconductor drum 21, and specifically, is the voltage value applied to the grid 233. When the control unit 51 starts the third regular execution process, it updates the grid bias value GBias_now stored in the main body memory 513 (update process S67). After executing the update process S67, the control unit 51 ends the third regular execution process.

[0144] <Fourth regular implementation process> FIG. 13 is a diagram showing the flow of the fourth periodic execution process executed by the control unit 51. The fourth periodic execution process is a process for updating the erase lamp state Elamp_now stored in the main body memory 513. The erase lamp state Elamp_now is information that indicates the current lighting state of the erase lamp 26, and is information that indicates whether the erase lamp 26 is on or off. When the control unit 51 starts the fourth periodic execution process, it updates the erase lamp state Elamp_now stored in the main body memory 513 (update process S68). After executing the update process S68, the control unit 51 ends the fourth periodic execution process.

[0145] <5th regular implementation process> FIG. 14 is a diagram showing the flow of the fifth regular execution process executed by the control unit 51. The fifth regular execution process is a process for updating the drum rotation speed D_spd_now stored in the main body memory 513. The drum rotation speed D_spd_now is information representing the current rotation speed of the photoconductor drum 21. When the control unit 51 starts the fifth regular process, it judges whether the photoconductor drum 21 is rotating (judgment process S71). When the control unit 51 judges that the photoconductor drum 21 is not rotating (No in the judgment process S71), it sets the drum rotation speed D_spd_now stored in the main body memory 513 to 0. When the control unit 51 judges that the photoconductor drum 21 is rotating (Yes in the judgment process S71), it judges whether the rotation speed of the photoconductor drum 21 has changed (judgment process S73). In the determination process S73, if the current rotation speed of the photoconductor drum 21 is different from the drum rotation speed D_spd_now stored in the main body memory 513, the control unit 51 determines that the rotation speed of the photoconductor drum 21 has changed. If the control unit 51 determines that the drum rotation speed D_spd_now has not changed (No in the determination process S73), the control unit 51 ends the fifth regular implementation process. If the control unit 51 determines that the drum rotation speed D_spd_now has changed (Yes in the determination process S73), the photoconductor drum 21 updates the rotation speed D_spd_now (update process S74). After executing the determination process S73, the control unit 51 ends the fifth regular implementation process.

[0146] <6th regular implementation process> 15 is a diagram showing the flow of the sixth regular execution process executed by the control unit 51. The sixth regular execution process is a process for updating the number of times of contact Dev_P_cnt and the number of times of separation Dev_R_cnt stored in the main body memory 513. The number of times of contact Dev_P_cnt is information indicating the number of times that the developing roller 31 has been pressed against the photosensitive drum 21. The number of times of contact Dev_P_cnt corresponds to the number of times Tr that the developing roller 31 has moved from the separated position to the contact position. The number of times of separation Dev_R_cnt is data indicating the number of times that the developing roller 31 has been separated from the photosensitive drum 21. The number of times of separation corresponds to the number of times Tp that the developing roller 31 has moved from the contact position to the separated position.

[0147] When the sixth regular execution process is started, the control unit 51 judges whether the developing roller 31 is in pressure contact with the photosensitive drum 21 (judgment process S81). When the control unit 51 judges that the developing roller 31 is in pressure contact with the photosensitive drum 21 (Yes in the judgment process S81), the control unit 51 judges whether the developing roller state S_dev_now stored in the main memory 513 is different from the pressure contact state (judgment process S82). The developing roller state S_dev_now is information indicating whether the developing roller 31 is in the pressure contact state (i.e., whether the developing roller 31 is in the contact position) or the separated state (i.e., whether the developing roller 31 is in the separated position). When the control unit 51 judges that the developing roller state S_dev_now is different from the pressure contact state (Yes in the judgment process S82), the control unit 51 updates the developing roller state S_dev_now stored in the main memory 513 to the pressure contact state (update process S83). After executing the update process S83, the control unit 51 increments the number of pressure contacts Dev_P_cnt stored in the main body memory 513 by one (addition process S84).

[0148] When the control unit 51 determines in the determination process S81 that the developing roller 31 is in a position separated from the photosensitive drum 21 (separated position) (No), the control unit 51 determines whether the developing roller state S_dev_now stored in the main body memory 513 is a pressure contact state (determination process S85). Note that when the control unit 51 determines in the determination process S82 that the developing roller state S_dev_now is a pressure contact state (No), it executes the determination process S85. Moreover, the control unit 51 executes the addition process S84 and then executes the determination process S85.

[0149] When the control unit 51 determines that the developing roller state S_dev_now is the pressed state (Yes in the determination process S85), it sets the developing roller state S_dev_now to the separated state (update process S86). After executing the update process S86, the control unit 51 increments the number of separation times Dev_R_cnt stored in the main body memory 513 by one (addition process S87).

[0150] When the control unit 51 determines in the determination process S85 that the developing roller state S_dev_now is not in the pressure contact state (No), the control unit 51 ends the sixth periodic execution process. After executing the addition process S87, the control unit 51 ends the sixth periodic execution process.

[0151] <7th regular implementation process> 16 and 17 are diagrams showing the flow of the seventh regular execution process executed by the control unit 51. The seventh regular execution process is a process for updating the parameter A for calculating the increase amount ΔY. When the control unit 51 starts the seventh regular execution process, it judges whether the developing roller state S_dev_now stored in the main body memory 513 is a pressed state (FIG. 16: judgment process S8a). When it is judged that the developing roller state S_dev_now is not a pressed state (i.e., the developing roller state S_dev_now is a separated state) (No in the judgment process S8a), the control unit 51 sets the parameter A stored in the main body memory 513 to zero (FIG. 16: update process S8b). After executing the update process S8b, the control unit 51 ends the seventh regular execution process.

[0152] When the control unit 51 determines in the determination process S8a that the developing roller state S_dev_now stored in the main body memory 513 is in the pressure contact state (Yes), it determines whether the erase lamp state Elamp_now stored in the main body memory 513 is in the on state (FIG. 16: determination process S8c). When the control unit 51 determines that the erase lamp state Elamp_now is in the on state (Yes in the determination process S8c), it determines whether the erase lamp state Elamp_now has been updated since the previous seventh regular execution process (FIG. 16: determination process S8d). Specifically, the control unit 51 refers to the previous erase lamp state S_el stored in the main body memory 513 and determines whether the previous erase lamp state S_el is different from the on state. The previous erase lamp state S_el is information that indicates the on state Elamp_now of the erase lamp 26 at the time of the previous seventh regular execution process.

[0153] When the control unit 51 determines through the determination process S8d that the erase lamp state Elamp_now has been updated (i.e., the previous erase lamp state S_el is different from the on state) (Yes), it updates the parameter A(1) stored in the main body memory 513 (FIG. 16: update process S8e). The parameter A(1) is a component that the parameter A has, and is a component that varies according to the erase lamp state Elamp_now. After executing the update process S8e, the control unit 51 updates the previous erase lamp state S_el stored in the main body memory 513 to the on state (FIG. 16: update process S8f).

[0154] When the control unit 51 determines that the erase lamp state Elamp_now is not in the on state by the determination process S8c (No), it determines whether the erase lamp state Elamp_now has been updated since the previous time (FIG. 16: determination process S8g). Specifically, the control unit 51 determines whether the previous erase lamp state S_el stored in the main body memory 513 is in the on state. When the control unit 51 determines that the erase lamp state Elamp_now has been updated (i.e., the previous erase lamp state S_el is in the on state) (Yes in the determination process S8g), it updates the parameter A(1) (FIG. 16: update process S8h). After executing the update process S8h, the control unit 51 updates the previous erase lamp state S_el to the off state (FIG. 16: update process S8i).

[0155] When the erase lamp 26 is on, silica of the developing roller 31 may adhere to the photoconductor drum 21 more easily than when the erase lamp 26 is off. In this case, the control unit 51 may set the parameter A(1) to be larger in the update process S8e when the erase lamp 26 is on than in the update process S8h when the erase lamp 26 is off. This allows the increase ΔY per rotation of the photoconductor drum 21 when the erase lamp 26 is on to be calculated to be larger than the increase ΔY per rotation of the photoconductor drum 21 when the erase lamp 26 is off. Therefore, the adhesion amount Y can be calculated appropriately.

[0156] After executing the update process S8f or after executing the update process S8i, the control unit 51 executes the determination process S8j (FIG. 17). If the control unit 51 determines in the determination process S8d that the erase lamp state Elamp_now has not been updated, or if the control unit 51 determines in the determination process S8g that the erase lamp state Elamp_now has not been updated, the control unit 51 skips the update process S8e and executes the determination process S8j.

[0157] In the determination process S8j, the control unit 51 determines whether the rotation speed of the photosensitive drum 21 has changed since the time of the previous seventh regular execution process. Specifically, the control unit 51 compares the drum rotation speed D_spd_now stored in the main memory 513 with the previous drum rotation speed D_spd_last. The previous drum rotation speed D_spd_last is information stored in the main memory 513 and is information representing the drum rotation speed D_spd_now at the time of the previous seventh regular execution process. When the control unit 51 determines that the drum rotation speed D_spd_now has changed (Yes in the determination process S8j), it updates the parameter A(2) stored in the main memory 513 to a value corresponding to the magnitude of the drum rotation speed D_spd_now (FIG. 17: update process S8k). The parameter A(2) is a component of the parameter A and is a component that varies according to the drum rotation speed D_spd_now. After executing the update process S8k, the control unit 51 updates the previous drum rotation speed D_spd_last stored in the main body memory 513 to the drum rotation speed D_spd_now (FIG. 17: update process S8l).

[0158] There are cases where the adhesion of silica to the photoconductor drum 21 increases as the rotation speed of the photoconductor drum 21 decreases. In this case, in the update process S8k, the control unit 51 may increase the parameter A(2) as the drum rotation speed D_spd_now decreases. This allows the control unit 51 to appropriately calculate the amount Y of silica adhesion.

[0159] When the control unit 51 determines in the determination process S8j that the drum rotation speed D_spd_now has not changed (No), it executes the determination process S8m. After executing the update process S8l, the control unit 51 executes the determination process S8m. In the determination process S8m, the control unit 51 determines whether the grid bias value GBias_now stored in the main body memory 513 has changed from the previous grid bias value GBias_last by exceeding a predetermined threshold value Th_gb. The previous grid bias value GBias_last is information stored in the main body memory 513, and is information representing the grid bias value GBias_now at the time of the previous seventh periodic execution process. The threshold value Th_gb may be, for example, 50 volts.

[0160] When the control unit 51 determines that the grid bias value GBias_now has changed from the previous grid bias value GBias_last by more than the threshold value Th_gb (Yes in the determination process S8m), it updates the parameter A(3) stored in the main body memory 513 (FIG. 17: update process S8n). The parameter A(3) is a component that the parameter A has, and is a component that varies according to the grid bias value GBias_now. After executing the update process S8n, the control unit 51 updates the previous grid bias value GBias_last stored in the main body memory 513 to the grid bias value GBias_now (FIG. 17: update process S8o).

[0161] When the control unit 51 determines in the determination process S8m that the grid bias value has not changed beyond the threshold (No), it executes the determination process S8p. After executing the update process S8o, the control unit 51 executes the determination process S8p. In the determination process S8p, the control unit 51 determines whether the humidity Hum_now stored in the main body memory 513 has changed from the previous humidity Hum_last beyond a predetermined threshold Th_Hum. The previous humidity Hum_last is information stored in the main body memory 513, and is information representing the humidity Hum_now at the time of the previous seventh periodic implementation process. The threshold Th_Hum may be a constant or may be a variable such as 10% of the previous humidity Hum_last.

[0162] When the control unit 51 determines in the determination process S8p that the humidity Hum_now has changed beyond the threshold value Th_Hum (Yes), the control unit 51 updates the parameter A(4) stored in the main body memory 513 to a value corresponding to the humidity Hum_now (update process S8q). The parameter A(4) is a component that the parameter A has and varies according to the humidity Hum_now. After executing the update process S8q, the control unit 51 updates the previous humidity Hum_last stored in the main body memory 513 to the humidity Hum_now (update process S8r).

[0163] The higher the humidity Hum_now, the greater the adhesion of silica to the photoconductor drum 21. For this reason, in the update process S8q, the control unit 51 may set the parameter A(4) to a larger value as the humidity Hum_now increases. As a result, the control unit 51 calculates the increase amount ΔY to be greater as the humidity Hum_now increases. For this reason, the adhesion amount Y can be appropriately calculated in accordance with the change in the humidity Hum_now.

[0164] The control unit 51 calculates parameter A by adding up parameters A(1) to A(4) stored in the main body memory 513 (calculation process S8s). After storing the calculated parameter A in the main body memory 513, the control unit 51 ends the seventh regular implementation process.

[0165] When the developing roller 31 is not in a pressure contact state (i.e., when the developing roller 31 is in the separated position), the parameter A is set to zero by the update process S8b. On the other hand, when the developing roller 31 is in a pressure contact state (i.e., when the developing roller 31 is in the contact position), the parameter A is calculated as a value greater than zero by the calculation process S8s. Also, as shown in equation (2), the larger the parameter A, the larger the increase amount ΔY. Therefore, the parameter A is a parameter that makes it easier for foreign matter to adhere to the photosensitive drum 21 when the developing roller 31 is in the contact position than when it is in the separated position.

[0166] <8th regular implementation process> 18, 19, and 20 are diagrams showing the flow of the eighth regular execution process executed by the control unit 51. The eighth regular execution process is a process for updating the parameter B for obtaining the increase amount ΔY. When the control unit 51 starts the eighth regular execution process, it determines whether the developing drum state S_dev_now stored in the main body memory 513 is the pressure contact state (FIG. 18: determination process S9a).

[0167] When the control unit 51 determines that the developing drum state S_dev_now is in a pressure contact state (Yes in the determination process S9a), it determines whether the drum rotation speed D_spd_now stored in the main memory 513 has changed from the previous drum rotation speed D_spd_last2 (FIG. 19: determination process S9b). The previous drum rotation speed D_spd_last2 is information stored in the main memory 513, and is information representing the drum rotation speed D_spd_now at the time of the previous eighth regular execution process. When the control unit 51 determines in the determination process S9b that the drum rotation speed D_spd_now has changed (Yes), it updates the parameter B(1) stored in the main memory 513 to a value corresponding to the drum rotation speed D_spd_now (FIG. 19: update process S9c). The parameter B(1) is a component that the parameter B has, and is a component that varies according to the drum rotation speed D_spd_now. After executing the update process S9c, the control unit 51 updates the previous drum rotation speed D_spd_last2 stored in the main body memory 513 to the value of the drum rotation speed D_spd_now (FIG. 19: update process S9d).

[0168] When the developing roller 31 is in pressure contact with the photosensitive drum 21, the cleaning roller 25 acts in a direction polishing the photosensitive drum 21 due to silica of the toner supplied by the developing roller 31 to the photosensitive drum 21. For this reason, the control unit 51 may set the parameter B(1) to a negative value in the update process S9c. This allows the adhesion amount Y calculated by the control unit 51 to be reduced. Also, the higher the rotation speed of the photosensitive drum 21, the greater the polishing force of the cleaning roller 25. For this reason, the control unit 51 may set the parameter B(1) to a negative value with a larger absolute value as the drum rotation speed D_spd_now increases in the update process S9c.

[0169] When the control unit 51 determines in the determination process S9b that the drum rotation speed D_spd_now has not changed (No), it executes the determination process S9e (FIG. 19). After executing the update process S9d, the control unit 51 executes the determination process S9e. In the determination process S9e, the control unit 51 determines whether the temperature Temp_now stored in the main memory 513 has changed from the previous temperature Temp_last by exceeding the threshold value Th_Temp. The previous humidity Temp_last is information stored in the main memory 513, and is information representing the temperature Temp_now at the time of the previous eighth periodic execution process. When the control unit 51 determines in the determination process S9e that the temperature Temp_now has changed from the previous time by exceeding the threshold value Th_Temp (Yes), it updates the parameter B(2) stored in the main memory 513 to a value corresponding to the temperature Temp_now (FIG. 19: update process S9f). After executing the update process S9f, the control unit 51 updates the previous temperature Temp_last (FIG. 19: update process S9g).

[0170] When the developing roller 31 is in pressure contact with the photosensitive drum 21, the silica of the toner supplied by the developing roller 31 to the photosensitive drum 21 causes the cleaning roller 25 to act in a direction polishing the photosensitive drum 21. For this reason, the control unit 51 may set the parameter B(2) to a negative value in the update process S9c. This allows the control unit 51 to reduce the adhesion amount Y calculated by the control unit 51 based on the above formulas (1) and (2). Also, the higher the temperature Temp_now, the smaller the polishing force of the cleaning roller 25 may become. In this case, the control unit 51 may set the parameter B(2) to a negative value with a smaller absolute value in the update process S9f, as the temperature Temp_now becomes higher.

[0171] After executing the update process S9g, the control unit 51 calculates the parameter B (calculation process S9z). When the control unit 51 determines in the determination process S9e that the temperature Tmep_now has not changed beyond the threshold value Th_Temp since the previous time (No), the control unit 51 executes the calculation process S9z. In the calculation process S9z, the control unit 51 calculates the parameter B by adding together the parameters B(1) and B(2) stored in the main body memory 513. When the parameters B(1) and B(2) are negative values, the parameter B also becomes a negative value. The control unit 51 stores the calculated parameter B in the main body memory 513, and ends the eighth periodic implementation process.

[0172] Returning to FIG. 18, when the control unit 51 determines that the development drum state S_dev_now is different from the pressure contact state (No) by the determination process S9a, it determines whether the erase lamp state Elamp_now is in the on state (FIG. 18: determination process S9h). When the control unit 51 determines that the erase lamp state Elamp_now is in the on state (Yes in the determination process S9h), it determines whether the erase lamp state Elamp_now has been updated (FIG. 18: determination process S9i). Specifically, the control unit 51 determines whether the previous erase lamp state S_el2 stored in the main body memory 513 is different from the on state. The previous erase lamp state S_el2 is information that represents the erase lamp state Elamp_now at the time of the previous eighth periodic execution process. When the control unit 51 determines that the erase lamp state Elamp_now has been updated by the determination process S9i (Yes), it updates the parameter B(3) stored in the main body memory 513 (update process S9j). Parameter B(3) is a component that parameter B has, and is a component that varies according to the erase lamp state Elamp_now. After executing the update process S9j, the control unit 51 updates the previous erase lamp state S_el2 stored in the main body memory 513 to the on state (update process S9k).

[0173] When the control unit 51 determines in the determination process S9h that the erase lamp state Elamp_now is not in the on state (No), it determines whether the erase lamp state Elamp_now has been updated (determination process S9l). Specifically, the control unit 51 determines whether the previous erase lamp state S_el2 is in the on state. When the control unit 51 determines that the erase lamp state Elamp_now has been updated (Yes in the determination process S9l), it updates the parameter B(3) (FIG. 18: update process S9m). After executing the update process S9m, the control unit 51 updates the previous erase lamp state S_el2 to the off state (FIG. 18: update process S9n).

[0174] When the developing roller 31 is separated from the photosensitive drum 21, the cleaning roller 25 may cause silica to adhere to the photosensitive drum 21. For this reason, the control unit 51 may set the parameter B(3) to a positive value in the updating process S9j and the updating process S9m. This allows the increase in silica ΔY caused by the cleaning roller 25 to be calculated as a positive value when the developing roller 31 is separated from the photosensitive drum 21. Therefore, the adhesion amount Y can be calculated appropriately.

[0175] Furthermore, when the erase lamp 26 is on, silica may adhere to the photoconductor drum 21 more easily than when the erase lamp 26 is off. For this reason, the control unit 51 may set the value of parameter B(3) to be larger in the update process S9j than in the update process S9m. In this case, the control unit 51 can calculate the increase amount ΔY to be larger when the erase lamp 26 is on than when the erase lamp 26 is off. Therefore, the amount Y of silica adhering to the photoconductor drum 21 can be appropriately calculated.

[0176] When the developing roller 31 is separated from the photoconductor drum 21, silica may adhere from the cleaning roller 25 to the photoconductor drum 21. For this reason, the control unit 51 may set the parameter B(5) to a positive value.

[0177] After executing the determination process S9i, the control unit 51 executes the determination process S9o (FIG. 20). Moreover, after executing the update processes S9k and S9n, the control unit 51 executes the determination process S9o. In the determination process S9o, the control unit 51 determines whether the drum rotation speed D_spd_now stored in the main memory 513 has changed from the previous drum rotation speed D_spd_last2. When the control unit 51 determines that the drum rotation speed D_spd_now has changed, the control unit 51 updates the parameter B(4) stored in the main memory 513 to a value corresponding to the drum rotation speed D_spd_now (FIG. 20: update process S9p). After executing the update process S9p, the control unit 51 updates the previous drum rotation speed D_spd_last2 stored in the main memory 513 to the drum rotation speed D_spd_now (FIG. 20: update process S9q).

[0178] When the developing roller 31 is separated from the photosensitive drum 21, silica may adhere from the cleaning roller 25 to the photosensitive drum 21. For this reason, the control unit 51 may set the parameter B(4) to a positive value. Also, the amount of silica adhering from the cleaning roller 25 to the photosensitive drum 21 may increase as the rotation speed of the photosensitive drum 21 decreases. For this reason, the control unit 51 may set the parameter (1) to a larger value as the drum rotation speed D_spd_now decreases.

[0179] When the control unit 51 determines in the determination process S9o that the drum rotation speed D_spd_now has not changed (No), it executes the determination process S9r. After executing the update process S9q, the control unit 51 executes the determination process S9r. In the determination process S9r, the control unit 51 determines whether the grid bias value GBias_now has changed from the previous grid bias value GBias_last2 by exceeding a predetermined threshold value Th_gb2. The previous grid bias value GBias_last2 is information stored in the main body memory 513, and is information representing the grid bias value GBias_now at the time of the previous eighth periodic execution process. When the control unit 51 determines in the determination process S9r that the grid bias value GBias_now has changed from the previous time by exceeding the threshold value Th_gb2 (Yes), it updates the parameter B(5) stored in the main body memory 513 to a value corresponding to the magnitude of the grid bias value GBias_now (FIG. 20: update process S9s). Parameter B(5) is a component of parameter B, and is a component that varies according to the grid bias value GBias_now. After executing the update process S9s, the control unit 51 updates the previous grid bias value GBias_last2 stored in the main body memory 513 to the grid bias value GBias_now (FIG. 20: update process S9t).

[0180] When the developing roller 31 is separated from the photoconductor drum 21, silica may adhere from the cleaning roller 25 to the photoconductor drum 21. For this reason, the control unit 51 may set the parameter B(5) to a positive value. Also, the amount of silica adhering from the cleaning roller 25 to the photoconductor drum 21 may decrease as the voltage applied by the charger 23 to the photoconductor drum 21 increases. For this reason, the control unit 51 may set the parameter B(5) to a smaller value in the update process S9s as the grid bias value GBias_now increases. This allows the adhesion amount Y to be calculated appropriately in accordance with changes in the grid bias value.

[0181] When the control unit 51 determines by the determination process S9r that the grid bias value GBias_now has not changed beyond the threshold value Th_gb2 since the previous time (No), it executes the determination process S9u. After executing the update process S9t, the control unit 51 executes the determination process S9u. In the determination process S9u, the control unit 51 determines whether the humidity Hum_now stored in the main memory 513 has changed from the previous humidity Hum_now2 by exceeding a predetermined threshold value Th_Hum2. The previous humidity Hum_last2 is information stored in the main memory 513, and is information representing the humidity Hum_now at the time of the previous eighth periodic implementation process. When the control unit 51 determines by the determination process S9u that the humidity Hum_now has changed from the previous time by exceeding the threshold value Th_Hum2 (Yes), it updates the parameter B(6) stored in the main memory 513 to a value corresponding to the level of the humidity Hum_now (FIG. 20: update process S9v). Parameter B(6) is a component of parameter B, and is a component that varies according to humidity Hum_now. After executing the update process S9v, the control unit 51 updates the previous humidity Hum_last2 stored in the main body memory 513 to the humidity Hum_now (FIG. 20: update process S9w).

[0182] When the developing roller 31 is separated from the photoconductor drum 21, silica may adhere from the cleaning roller 25 to the photoconductor drum 21. For this reason, the control unit 51 may set the parameter B(6) to a positive value. Also, the higher the humidity, the stronger the adhesion of silica to the photoconductor drum 21. For this reason, in the update process S9v, the control unit 51 may set the parameter B(6) to a larger value as the humidity Hum_now increases. This allows the control unit 51 to appropriately calculate the adhesion amount Y in accordance with changes in the humidity Hum_now.

[0183] After executing the update process S9w, the control unit 51 calculates the parameter B (calculation process S9x). When the control unit 51 determines in the determination process S9u that the humidity Hum_now has not changed beyond the threshold value Th_Hum2 since the previous time (No), the control unit 51 executes the calculation process S9x. In the calculation process S9x, the control unit 51 calculates the parameter B by adding together the parameters B(3), B(4), B(5), and B(6) stored in the main body memory 513. When the parameters B(3) to B(6) are positive values, the parameter B is also a positive value. The control unit 51 stores the calculated parameter B in the main body memory 513, and ends the eighth periodic implementation process.

[0184] <Adhesion amount renewal process> FIG. 21 is a diagram showing the flow of the adhesion amount update process executed by the control unit 51. The adhesion amount update process is a process for updating the adhesion amount Y stored in the main memory 513. The control unit 51 may execute the adhesion amount update process periodically or whenever a predetermined event occurs. When the control unit 51 starts the adhesion amount update process, it judges whether the parameter A stored in the main memory 513 is different from the previous parameter A' (judgment process S10a). The previous parameter A' is information stored in the main memory 513 and represents the parameter A at the time of the previous adhesion amount update process. When the control unit 51 judges that the parameter A is the same as the previous parameter A' (No in the judgment process S10a), it judges whether the parameter B stored in the main memory 513 is different from the previous parameter B' (judgment process S10b). The previous parameter B' is information stored in the main memory 513 and represents the parameter B at the time of the previous adhesion amount update process. When the control unit 51 determines that the parameter B is the same as the previous parameter B' (No in the determination process S10b), it determines whether the drum rotation speed Dr_R stored in the main body memory 513 has exceeded a predetermined threshold value Th_Dr_r (determination process S10c). The drum rotation speed Dr_R is information that represents the rotation speed (ΔX) of the photosensitive drum 21. When the control unit 51 determines that the drum rotation speed Dr_R has not exceeded the threshold value Th_Dr_r (No in the determination process S10c), it ends the adhesion amount calculation process.

[0185] When the control unit 51 determines in the determination process S10a that the parameter A is different from the previous parameter A' (Yes), it calculates the increase amount ΔY based on the formula (2) (calculation process S10d). When the control unit 51 determines in the determination process S10b that the parameter B is different from the previous parameter B' (Yes), it executes the calculation process S10d. In the calculation process S10d, the control unit 51 substitutes the drum rotation number Dr_R, the number of pressure contacts Dev_R_cnt, and the number of separations Dev_P_cnt for ΔX, Tr, and Tp in the formula (2), respectively. The control unit 51 also substitutes the parameters A, B, C, and D stored in the main body memory 513 into the formula (2). In this way, the control unit 51 calculates the increase amount ΔY.

[0186] When parameters A and B change, the rate of increase or decrease of the silica adhesion amount Y may change. Therefore, by calculating the increase amount ΔY at the time when at least one of parameters A and B changes, the adhesion amount Y can be appropriately obtained.

[0187] When the control unit 51 determines in the determination process S10c that the drum rotation speed Dr_R exceeds the threshold value Th_Dr_r (Yes), it executes the calculation process S10d. This allows the control unit 51 to calculate the increase amount ΔY when the drum rotation speed reaches a certain level. This makes it possible to prevent the increase amount ΔY from being omitted when calculating the adhesion amount Y.

[0188] The control unit 51 adds the increase ΔY calculated by the calculation process S10d to the adhesion amount Y stored in the main memory 513 (addition process S10e). After executing the addition process S10e, the control unit 51 updates the previous parameter A' stored in the main memory 513 to parameter A, and updates the previous parameter B' stored in the main memory 513 to parameter B (update process S10f). Note that in the update process S10f, the control unit 51 may update only the updated parameter out of parameters A and B.

[0189] After calculating the increase ΔY by the calculation process S10d, the control unit 51 clears the number of pressure contacts Dev_R_cnt and the number of separations Dev_P_cnt (clearing process S10g). After calculating the increase ΔY by the calculation process S10d, the control unit 51 clears the drum rotation number count Dr_R (clearing process S10h).

[0190] After calculating the adhesion amount Y by the addition process S10e, the control unit 51 writes the calculated adhesion amount Y into the main body memory 513 (writing process S10i). After executing the writing process S10i, the control unit 51 ends the adhesion amount calculation process.

[0191] As described above, in the image forming apparatus 1, the photoconductor drum 21 rotates while being in contact with the developing roller 31 or the cleaning roller 25, so the amount of silica adhering to the photoconductor drum 21 can change depending on the rotation speed of the photoconductor drum 21. Therefore, the amount Y of silica adhering to the photoconductor drum 21 can be appropriately calculated based on the rotation speed of the photoconductor drum 21 and parameters A and B indicating the ease with which silica adheres to the photoconductor drum 21.

[0192] 9, by comparing the calculated amount Y of silica adhesion with the thresholds Th_5e and Th_5, it is possible to detect an abnormality in the drum cartridge 20 due to adhesion of silica. This makes it possible to predict the occurrence of an abnormality in the drum cartridge 20, thereby preventing a decrease in print quality.

[0193] <2. Modification> Although the embodiments have been described above, the present disclosure is not limited to the above, and various modifications are possible.

[0194] For example, the charger 23 does not necessarily have to be a scorotron type, but may be of another type such as a charging roller.

[0195] The server 7 is an example of a communication device, and the communication device is not limited to the server 7. The communication device may be an information terminal such as a PC, a smartphone, or a tablet. The control unit 51 of the image forming apparatus 1 may transmit order information (including drum information in the second embodiment) to the information terminal. In this case, the information terminal may transmit the order information to the server 7. E-mail may also be used for data communication between the devices.

[0196] The image forming apparatus 1 is configured as a color printer equipped with toner cartridges 30 of multiple colors, but may be a monochrome printer. When the image forming apparatus is a monochrome printer, a drum cartridge having one photosensitive drum 21 may be provided for one toner cartridge 30. In addition, it is not essential that the drum cartridge 20 is configured to hold four toner cartridges 30 at the same time. FIG. 22 is a schematic diagram showing an image forming apparatus 1a of a modified example. The image forming apparatus 1a has a main body housing 10a, and four drum cartridges 20a are replaceably mounted in the main body housing 10a. Each drum cartridge 20a has one photosensitive drum 21 and a drum memory 22. One toner cartridge 30 is replaceably mounted in each drum cartridge 20a. The image forming apparatus 1a may be applied to the image forming system 100 shown in FIG. 1.

[0197] Although the toner cartridge 30 includes the developing roller 31, it is not essential that the toner cartridge 30 includes the developing roller 31. For example, the drum cartridge 20 may include the developing roller 31. The image processing device 1 may also include a three-component cartridge. The three-component cartridge includes a toner cartridge 30 that does not have a developing roller, a drum cartridge 20, and a developing cartridge that includes the developing roller 31. In this case, the developing cartridge may be mountable to the drum cartridge 20, and the toner cartridge 30 may be mountable to the drum cartridge 20.

[0198] Although the present disclosure has been described in detail, the above description is illustrative in all respects, and the present disclosure is not limited thereto. It is understood that countless variations not illustrated can be envisioned without departing from the scope of this disclosure. The configurations described in the above embodiments and variations may be combined or omitted as long as they are not mutually inconsistent. [Explanation of symbols]

[0199] 1,1a Image forming device 7 Server (communication device) 17 Temperature Sensor 18 Humidity Sensor 19 Drive unit 20,20a drum cartridge 21 Photoconductor drum 22 Drum Memory 23 Charger 25 Cleaning roller 26 Erase Lamp 30 Toner Cartridge 31 Developing roller 31 Photoconductor drum 51 Control section 55 Display 57 Communication Interface

Claims

1. An image forming apparatus, a drum cartridge having a photosensitive drum rotatable about a rotation shaft; A memory that stores the number of rotations of the photosensitive drum; A control unit; A developing roller; Equipped with The control unit is an adhesion amount calculation process for calculating an adhesion amount of foreign matter adhered to the photosensitive drum based on the rotation speed of the photosensitive drum stored in the memory and a parameter indicating the ease with which foreign matter adheres to the photosensitive drum; a threshold determination process for determining whether the adhesion amount calculated by the adhesion amount calculation process exceeds a predetermined threshold; It is possible to execute The image forming apparatus, wherein the parameters include a first parameter indicating the tendency of foreign matter to adhere from the developing roller to the photosensitive drum.

2. 2. The image forming apparatus according to claim 1, The adhesion amount calculation process includes: a process in which the control unit calculates an increase in the amount of foreign matter adhering to the photosensitive drum, the increase corresponding to the number of rotations of the photosensitive drum stored in the memory; a process in which the control unit calculates the adhesion amount by accumulating the increased amount; An image forming apparatus comprising:

3. 3. The image forming apparatus according to claim 1, a drive unit that moves the developing roller between a contact position where the developing roller is in contact with the photosensitive drum and a separation position where the developing roller is separated from the photosensitive drum; Further equipped with An image forming apparatus characterized in that the first parameter is a parameter that makes it easier for foreign matter to adhere to the photosensitive drum when the developing roller is in the contact position than when the developing roller is in the separated position.

4. 3. The image forming apparatus according to claim 2, a drive unit that moves the developing roller between a contact position where the developing roller is in contact with the photosensitive drum and a separation position where the developing roller is separated from the photosensitive drum; Further equipped with an image forming apparatus characterized in that the first parameter is a parameter that makes the increase amount calculated by the control unit in accordance with the rotation speed of the photosensitive drum when the developing roller is in the separated position smaller than the increase amount calculated by the control unit in accordance with the rotation speed of the photosensitive drum when the developing roller is in the contact position.

5. 5. The image forming apparatus according to claim 1, The drum cartridge further includes a cleaning member for cleaning the surface of the photosensitive drum, The image forming apparatus according to claim 1, wherein the parameters include a second parameter indicating a tendency of foreign matter to adhere from the cleaning member to the photosensitive drum.

6. 5. The image forming apparatus according to claim 1, The drum cartridge further includes a cleaning member for cleaning the surface of the photosensitive drum, the parameters further include a second parameter indicating the tendency of foreign matter to adhere from the cleaning member to the photosensitive drum, The image forming apparatus is characterized in that the adhesion amount calculation process calculates the amount of foreign matter adhering to the photosensitive drum based on the rotation speed of the photosensitive drum stored in the memory, the first parameter, and the second parameter.

7. 7. The image forming apparatus according to claim 5, The image forming apparatus according to claim 1, wherein the second parameter is a parameter for increasing or decreasing the amount of toner adhesion calculated by the control unit.

8. The image forming apparatus according to any one of claims 1 to 7, an erase lamp that discharges electricity from the surface of the photosensitive drum by irradiating the surface of the photosensitive drum with light; Further equipped with The control unit is a lighting determination process for determining whether the erase lamp is lit; It is possible to execute The image forming apparatus is characterized in that the parameter is a parameter that increases the amount of foreign matter adhering to the photosensitive drum when it is determined in the lighting determination process that the erase lamp is on, compared to the amount of foreign matter adhering to the photosensitive drum when it is determined in the lighting determination process that the erase lamp is not on.

9. 9. The image forming apparatus according to claim 1, Further comprising a developing roller, The image forming apparatus, wherein the parameter is a parameter for varying the amount of toner adhesion based on a rotation speed of the photosensitive drum.

10. 10. The image forming apparatus according to claim 1, Further comprising a developing roller, The control unit is a storage process for storing the cumulative number of rotations of the developing roller in the memory; It is possible to execute The image forming apparatus according to claim 1, wherein the parameter is a parameter for varying the amount of toner adhesion based on a cumulative number of rotations of the developing roller stored in the memory.

11. The image forming apparatus according to any one of claims 1 to 10, a charger for charging the photosensitive drum; Further equipped with The image forming apparatus is characterized in that the parameter is a parameter that increases the adhesion amount calculated by the control unit to a greater extent as the magnitude of the voltage applied by the charger to the photosensitive drum increases.

12. The image forming apparatus according to any one of claims 1 to 11, A temperature detector for detecting temperature, Further equipped with The image forming apparatus according to claim 1, wherein the parameter is a parameter for varying the amount of toner adhesion based on a temperature detected by the temperature detector.

13. 13. The image forming apparatus according to claim 1, A humidity detector that detects humidity, Further equipped with The image forming apparatus according to claim 1, wherein the parameter is a parameter for varying the amount of toner adhesion based on the humidity detected by the humidity detector.

14. The image forming apparatus according to any one of claims 1 to 13, A developing roller; a drive unit that moves the developing roller between a contact position where the developing roller is in contact with the photosensitive drum and a separation position where the developing roller is separated from the photosensitive drum; Further equipped with an image forming apparatus, characterized in that the adhesion amount calculation process includes a process in which the control unit calculates the adhesion amount based on at least one of the number of times the developing roller moves from the separation position to the contact position or the number of times the developing roller moves from the contact position to the separation position, the rotation speed of the photosensitive drum, and the parameters.

15. 15. The image forming apparatus according to claim 14, an image forming apparatus, characterized in that the adhesion amount calculation process includes a process in which the control unit calculates the adhesion amount based on the number of times the developing roller moves from the separation position to the contact position, the number of times the developing roller moves from the contact position to the separation position, the rotation speed of the photosensitive drum, and the parameters.

16. 16. The image forming apparatus according to claim 1, The threshold determination process includes a process in which the control unit determines whether the adhesion amount exceeds a first threshold, The control unit is a usage restriction process for restricting usage of the drum cartridge when it is determined that the amount of toner adhesion exceeds a first threshold by the threshold determination process; 13. An image forming apparatus comprising:

17. 17. The image forming apparatus according to claim 1, display, Further equipped with The threshold determination process includes a process in which the control unit determines whether the adhesion amount exceeds a first threshold, When the threshold determination process determines that the amount of toner adhesion has exceeded a first threshold, the control unit executes a display process to display information on the display encouraging replacement of the drum cartridge.

18. 18. The image forming apparatus according to claim 1, The control unit further includes a communication interface for communicating with a communication device via a network, The control unit is a transmission process of transmitting information for ordering a new drum cartridge to the communication device via the communication interface based on the amount of adhesion; 13. An image forming apparatus comprising:

Images