Image formation control method and image forming device

Abstract

To appropriately adjust an electrification voltage or a developing bias voltage on the basis of the detection result of a current flowing in a developing bias voltage transmission path.SOLUTION: A control device 8 executes non-output control for causing voltage output circuits 71, 72 not to output an electrification voltage and a developing bias voltage. The control device 8 stores a dark current detected by a current detection circuit 73 when the non-output control is being executed. The control device 8 executes output control for causing the voltage output circuits 71, 72 to output the electrification voltage and the developing bias voltage (S3, S4, S10). The control device 8 derives an estimate leak current in response to the detected humidity of a humidity detection unit 74 and the developing bias voltage. The control device 8 adjusts one or both of the electrification voltage and the developing bias voltage so that the dark current, the estimate leak current, and a total current detected when the output control is being executed satisfy a target condition (S6-S9).SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an image formation control method and an image formation control device that executes a process for adjusting a charging voltage or a developing bias voltage. [Background technology]

[0002] In an electrophotographic image forming apparatus, in order to obtain a good output image, it is necessary to adjust the surface potential of the photosensitive member and the developing bias voltage in an appropriate balance.

[0003] If the balance between the surface potential of the photoconductor and the developing bias voltage is not appropriate, a developing current corresponding to the potential difference between the two flows between a circuit that outputs the developing bias voltage and a developing body such as a developing roller. Therefore, it is possible to specify the surface potential of the photoconductor based on the developing current and the developing bias voltage.

[0004] For example, it is known to determine the surface potential of a photosensitive body by detecting the current flowing from the developing roller to the photosensitive body when a predetermined image pattern is formed on the surface of the photosensitive body (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-295540 Summary of the Invention [Problem to be solved by the invention]

[0006] However, since the developing bias voltage is high, a leakage current occurs in the transmission path of the developing bias voltage, and therefore the current detected in the transmission path of the developing bias voltage includes currents other than the developing current, such as the leakage current.

[0007] Current other than the development current flowing through the transmission path of the development bias voltage adversely affects the adjustment of the charging voltage or the development bias voltage.

[0008] An object of the present invention is to provide an image formation control method and an image forming apparatus that can appropriately adjust the charging voltage or the developing bias voltage based on the detection result of the current flowing in the transmission path of the developing bias voltage. [Means for solving the problem]

[0009] An image formation control method according to one aspect of the present invention is a method for controlling an image forming apparatus. The image formation control method is executed when the image forming apparatus includes a photoconductor, a charging device, a developing device, a voltage output board, and a humidity detection unit. The charging device charges the surface of the photoconductor. The developing device has a developer that is disposed opposite the surface of the photoconductor and carries toner, and supplies the toner from the developer to the photoconductor. The voltage output board includes a voltage output circuit that outputs a charging voltage to the charging device and a developing bias voltage to the developer, and a current detection circuit that detects a current flowing in a developing bias transmission path that transmits the developing bias voltage. The humidity detection unit detects humidity within the image forming apparatus. The image formation control method includes a control device executing non-output control that prevents the voltage output circuit from outputting the charging voltage and the developing bias voltage. The image formation control method further includes the control device storing a dark current, which is a current detected by the current detection circuit when the non-output control is being executed. The image formation control method further includes the control device executing output control to cause the voltage output circuit to output the charging voltage and the developing bias voltage. The image formation control method further includes the control device acquiring the humidity detected by the humidity detection unit when the output control is being executed. The image formation control method further includes the control device deriving an estimated leakage current based on the detected humidity and the developing bias voltage when the output control is being executed. The image formation control method further includes the control device adjusting one or both of the charging voltage and the developing bias voltage in the output control so that the dark current, the estimated leakage current, and a total current, which is a current detected by the current detection circuit when the output control is being executed, satisfy target conditions.

[0010] An image forming apparatus according to another aspect of the present invention includes the photosensitive member, the charging device, the developing device, the voltage output board, the humidity detection unit, and the control device that realizes the image formation control method. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide an image formation control method and an image forming apparatus that can appropriately adjust the charging voltage or the developing bias voltage based on the detection results of the current flowing in the transmission path of the developing bias voltage. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram illustrating the configuration of an image forming apparatus according to an embodiment. [Figure 2] FIG. 2 is a block diagram showing the configuration of a control device in the image forming apparatus according to the embodiment. [Figure 3] FIG. 3 is a configuration diagram of a voltage output board in the image forming apparatus according to the embodiment. [Figure 4] FIG. 4 is a flowchart showing an example of a procedure for voltage adjustment processing in the image forming apparatus according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the following embodiment is an example of the present invention, and does not limit the technical scope of the present invention.

[0014] The image forming apparatus 10 according to the embodiment is an apparatus that performs a printing process using an electrophotographic method. The printing process is a process of forming an image on a sheet 9. The sheet 9 is an image forming medium such as paper or a sheet-like resin member.

[0015] [Configuration of image forming apparatus 10] 1, the image forming apparatus 10 includes a sheet storage unit 2, a sheet transport path 30, a sheet transport device 3, and a printing device 4. The image forming apparatus 10 further includes an operation device 801, a display device 802, and a control device 8.

[0016] The sheet transport path 30, the sheet transport device 3, the printing device 4, and the control device 8 are housed in a housing 1.

[0017] The sheet conveying device 3 sends out the sheet 9 stored in the sheet storage unit 2 to the sheet conveying path 30 , and further conveys the sheet 9 along the sheet conveying path 30 .

[0018] Furthermore, the sheet conveying device 3 discharges the sheet 9 on which the image has been formed from the sheet conveying path 30 onto the discharge tray 101.

[0019] The printing device 4 performs the printing process on the sheet 9 conveyed along the sheet conveying path 30. The printing device 4 forms a toner image on the sheet 9 conveyed along the sheet conveying path 30.

[0020] The toner image is an image formed using toner as a developer, and the toner is an example of the granular developer.

[0021] The printing device 4 includes one or more image forming units 4x, an optical scanning device 40, a transfer device 44, and a fixing device 46. In this embodiment, the printing device 4 is a tandem color printing device, and therefore includes multiple image forming units 4x corresponding to multiple development colors.

[0022] In this embodiment, the plurality of developing colors are four colors: yellow, cyan, magenta, and black, and therefore the printing device 4 includes four image forming units 4x.

[0023] Each image forming unit 4x includes a drum-shaped photosensitive member 41, a charging device 42, a developing device 43, a drum cleaning device 45, and the like.

[0024] In each image forming unit 4x, a photoconductor 41 rotates, and a charging device 42 charges the surface of the photoconductor 41. The charging device 42 is disposed opposite the photoconductor 41 and includes a charging member 421 that rotates.

[0025] In this embodiment, the charged member 421 is a charging roller that comes into contact with the surface of the photoconductor 41. The charged member 421 charges the surface of the photoconductor 41 by applying a charging voltage VC1.

[0026] The optical scanning device 40 scans the surface of the charged photoreceptor 41 with laser light to form an electrostatic latent image on the surface of the photoreceptor 41. The optical scanning device 40 is an example of an exposure device that exposes the surface of the charged photoreceptor 41 to light.

[0027] The developing device 43 develops the electrostatic latent image into a toner image by supplying the toner to the surface of the photoreceptor 41. The developing device 43 is disposed opposite the photoreceptor 41 and includes a developing body 431 that carries the toner and rotates.

[0028] In this embodiment, the developing body 431 is a developing roller arranged with a small gap between it and the surface of the photosensitive body 41. A developing bias voltage VD1 is applied to the developing body 431, and the developing body 431 rotates while carrying the toner.

[0029] The toner carried on the developing body 431 is transferred to the surface of the photoreceptor 41 due to the potential difference between the electrostatic latent image on the surface of the photoreceptor 41 and the surface of the developing body 431 .

[0030] For example, the developing device 43 charges the toner by stirring a two-component developer containing the toner and a carrier. Furthermore, the developing device 43 supplies the charged toner from the developing body 431 to the photoconductor 41.

[0031] The carrier is a granular material having magnetic properties. For example, the carrier is a granular magnetic material having a surface coating. The coating is made of a synthetic resin such as an epoxy resin.

[0032] The transfer device 44 transfers the toner image on the surface of each photoreceptor 41 onto the sheet 9 being transported along the sheet transport path 30 .

[0033] In this embodiment, the transfer device 44 includes an intermediate transfer belt 441, four primary transfer devices 442 corresponding to the four image forming units 4x, a secondary transfer device 443, and a belt cleaning device 444.

[0034] The intermediate transfer belt 441 is supported by a plurality of support rollers 440. One of the plurality of support rollers 440 is rotated by power received from a motor (not shown), thereby causing the intermediate transfer belt 441 to rotate.

[0035] In the transfer device 44 , the four primary transfer devices 442 transfer the toner images formed on the surfaces of the four photosensitive members 41 onto the surface of the intermediate transfer belt 441 .

[0036] The secondary transfer device 443 transfers the toner image formed on the surface of the intermediate transfer belt 441 onto the sheet 9 being transported along the sheet transport path 30 .

[0037] The drum cleaning device 45 removes waste toner remaining on the surface of the photosensitive member 41. The belt cleaning device 444 removes the waste toner remaining on the intermediate transfer belt 441. The waste toner is generated in the printing device 4 as the toner image is formed.

[0038] The fixing device 46 applies heat and pressure to the toner image on the sheet 9. In this way, the fixing device 46 fixes the toner image to the sheet 9.

[0039] The operation device 801 is a device that accepts operations by a person, and includes, for example, operation buttons and a touch panel.

[0040] The display device 802 is a device that displays information, and includes, for example, a panel display device such as a liquid crystal display unit.

[0041] [Configuration of control device 8] As shown in FIG. 2, the control device 8 includes a central processing unit (CPU) 81, a random access memory (RAM) 82, a secondary storage device 83, a signal interface 84, a communication device 85, and the like.

[0042] The secondary storage device 83 is a computer-readable non-volatile storage device. The secondary storage device 83 can store and update computer programs and various data. For example, a flash memory or a hard disk drive, or both, may be used as the secondary storage device 83.

[0043] The signal interface 84 converts signals output by various sensors into digital data and transmits the converted digital data to the CPU 81. Furthermore, the signal interface 84 converts control commands output by the CPU 81 into control signals and transmits the control signals to the devices to be controlled.

[0044] The communication device 85 executes communication with other devices such as a host device (not shown). The CPU 81 communicates with the other devices through the communication device 85.

[0045] The CPU 81 is a processor that executes the computer program to perform various data processing and control operations. The control device 8 including the CPU 81 controls the sheet transport device 3, the printing device 4, the display device 802, the communication device 85, etc.

[0046] The RAM 82 is a computer-readable volatile storage device that temporarily stores the computer programs executed by the CPU 81 and data that is output and referenced by the CPU 81 during the execution of various processes.

[0047] The CPU 81 executes the computer programs to perform various data processing and control operations.

[0048] The control device 8 further includes a voltage output board 86 including circuits for generating and outputting the charging voltage VC1 and the developing bias voltage VD1. The CPU 81 controls the voltage output board 86 through the signal interface 84 to adjust the levels of the charging voltage VC1 and the developing bias voltage VD1.

[0049] The voltage output board 86 also includes a circuit that outputs a transfer voltage to each of the primary transfer devices 442 and the secondary transfer device 443 .

[0050] [Configuration of voltage output board 86] As shown in FIG. 3, the voltage output board 86 has a charging voltage output circuit 71, a developing voltage output circuit 72, and a current detection circuit 73 mounted thereon.

[0051] The charging voltage output circuit 71 generates a charging voltage VC1 and outputs the charging voltage VC1 to the charged body 421 of the charging device 42. Furthermore, the charging voltage output circuit 71 turns on or off the output of the charging voltage VC1 to the charged body 421 in accordance with a charging voltage command SC1 received from the CPU 81.

[0052] Furthermore, when the charging voltage command SC1 indicates a voltage level, the charging voltage output circuit 71 can also change the level of the charging voltage VC1 in accordance with the charging voltage command SC1.

[0053] The developing voltage output circuit 72 generates a developing bias voltage VD1 and outputs the developing bias voltage VD1 to the developing body 431 of the developing device 43. Furthermore, the developing voltage output circuit 72 turns on or off the output of the developing bias voltage VD1 to the developing body 431 in accordance with a developing voltage command SC2 received from the CPU 81.

[0054] Furthermore, when the development voltage command SC2 indicates a voltage level, the development voltage output circuit 72 can also change the level of the development bias voltage VD1 in accordance with the development voltage command SC2.

[0055] The charging voltage output circuit 71 and the developing voltage output circuit 72 are examples of voltage output circuits that output the charging voltage VC1 and the developing bias voltage VD1.

[0056] The current detection circuit 73 detects the current flowing through the development bias transmission path that transmits the development bias voltage VD1.

[0057] Furthermore, a temperature and humidity sensor 74 is mounted on the voltage output board 86. The temperature and humidity sensor 74 detects the temperature and humidity around the voltage output board 86 inside the image forming apparatus 10. The temperature and humidity sensor 74 is an example of a temperature detection unit and an example of a humidity detection unit.

[0058] The temperature T1 and humidity H1 detected by the temperature and humidity sensor 74 are transmitted to the CPU 81 through the signal interface 84.

[0059] The CPU 81 includes a plurality of processing modules that are realized by executing the computer programs, including a main processing unit 8a and a job control unit 8b.

[0060] The main processing unit 8a executes processes to start various processes in response to operations on the operation device 801, controls the display device 802, and the like.

[0061] The job control unit 8b controls the sheet conveying device 3. As a result, the job control unit 8b controls the feeding of the sheet 9 from the sheet storage unit 2 and the conveyance of the sheet 9 in the sheet conveying path 30.

[0062] Furthermore, the job control unit 8b controls the printing device 4. In synchronization with the conveyance of the sheet 9 by the sheet conveying device 3, the job control unit 8b causes the printing device 4 to execute the printing process.

[0063] The job control unit 8b generates print data based on the image data of the print target. Furthermore, the job control unit 8b causes the optical scanning device 40 to execute a process of exposing the surface of the photosensitive member 41 in accordance with the print data. As a result, the optical scanning device 40 forms the electrostatic latent image on the surface of the photosensitive member 41.

[0064] Furthermore, the job control section 8b can also control the charging voltage VC1, the developing bias voltage VD1, and the transfer voltage.

[0065] In the image forming apparatus 10, in order to obtain a good output image, it is necessary to adjust the surface potential of the photosensitive member 41 and the developing bias voltage VD1 in an appropriate balance.

[0066] As described above, the voltage output board 86 includes the current detection circuit 73 that detects the current flowing through the transmission path of the development bias voltage VD1 (see FIG. 3).

[0067] If the balance between the surface potential of the photoconductor 41 and the developing bias voltage VD1 is not appropriate, a developing current Id3 corresponding to the potential difference between the two flows between the developing voltage output circuit 72 and the developing body 431. Therefore, it is possible to determine the surface potential of the photoconductor 41 based on the developing current Id3 and the developing bias voltage VD1.

[0068] In the image forming apparatus 10, the plurality of processing modules of the CPU 81 include an adjusting unit 8c. The adjusting unit 8c adjusts the charging voltage VC1 or the developing bias voltage VD1 in accordance with the detection result of the current detection circuit 73.

[0069] However, because the development bias voltage VD1 is a high voltage, a leakage current Id2 occurs in the transmission path of the development bias voltage VD1 (see FIG. 3). Therefore, the current detected in the transmission path of the development bias voltage VD1 includes currents other than the development current Id3, such as the leakage current Id2.

[0070] Currents other than the development current Id3 flowing through the transmission path of the development bias voltage VD1 have an adverse effect on the adjustment of the charging voltage VC1 or the development bias voltage VD1. The adjustment unit 8c adjusts one or both of the charging voltage VC1 and the development bias voltage VD1 by performing a voltage adjustment process described below.

[0071] [Voltage regulation processing] An example of the procedure for the voltage adjustment process will be described below with reference to the flowchart shown in FIG.

[0072] For example, the adjusting unit 8c executes the voltage adjusting process before the start of the printing process every time a request for the printing process is made. The voltage adjusting process is a process for setting one or both of the level of the charging voltage VC1 and the level of the developing bias voltage VD1 employed in the printing process.

[0073] The voltage adjustment process is an example of a process that realizes an image formation control method for controlling the image forming apparatus 10. In this embodiment, the adjustment unit 8c of the control device 8 realizes the image formation control method.

[0074] In the following description, S1, S2, ... represent identification codes of a plurality of steps in the voltage adjustment process. In the voltage adjustment process, step S1 is executed first.

[0075] <Process S1> In step S1, the adjusting section 8c controls the charging voltage output circuit 71 and the developing voltage output circuit 72 to turn off the outputs of the charging voltage VC1 and the developing bias voltage VD1.

[0076] The process of step S1 is an example of non-output control that prevents the charging voltage output circuit 71 and the developing voltage output circuit 72 from outputting the charging voltage VC1 and the developing bias voltage VD1.

[0077] In the following description, the state in which the output of the charging voltage VC1 and the developing bias voltage VD1 is turned off is referred to as the voltage-off state, and the state in which the output of the charging voltage VC1 and the developing bias voltage VD1 is turned on is referred to as the voltage-on state.

[0078] After performing the process of step S1, the adjuster 8c performs the process of step S2.

[0079] <Process S2> In step S2, the adjuster 8c acquires the dark current Id1, which is the current detected by the current detection circuit 73 in the voltage-off state, and stores the dark current Id1. For example, the adjuster 8c records the dark current Id1 acquired from the current detection circuit 73 in the secondary storage device 83.

[0080] After performing the process of step S2, the adjuster 8c performs the process of step S3.

[0081] <Process S3> In step S3, the adjusting section 8c sets the levels of the charging voltage VC1 and the developing bias voltage VD1 to preset reference levels.

[0082] The set levels of the charging voltage VC1 and the developing bias voltage VD1 are reflected the next time the output of the charging voltage VC1 and the developing bias voltage VD1 is turned ON.

[0083] After performing the process of step S3, the adjuster 8c performs the process of step S4.

[0084] <Process S4> In step S4, the adjusting section 8c controls the charging voltage output circuit 71 and the developing voltage output circuit 72 to turn on the output of the charging voltage VC1 and the developing bias voltage VD1.

[0085] By performing the process of step S4, the charging voltage VC1 and the developing bias voltage VD1 at the levels set in step S3 are output to the charging body 421 and the developing body 431, respectively. That is, the state in the steps after step S4 is the voltage ON state.

[0086] After performing the process of step S4, the adjuster 8c performs the process of step S5.

[0087] <Process S5> In step S5, the adjustment unit 8c acquires the temperature T1 and humidity H1 detected by the temperature and humidity sensor 74 in the voltage-on state.

[0088] After performing the process of step S5, the adjuster 8c performs the process of step S6.

[0089] <Process S6> In step S6, the adjusting section 8c derives the estimated leakage current Id20 according to the detected temperature T1, the detected humidity H1, and the current developing bias voltage VD1 in the voltage-on state.

[0090] In the voltage output board 86, a leakage current Id2 corresponding to the level of the developing bias voltage VD1 and the impedance of the voltage output board 86 flows.

[0091] The impedance of the voltage output board 86 changes depending on the amount of moisture around the voltage output board 86. Specifically, the greater the amount of moisture around the voltage output board 86, the lower the impedance of the voltage output board 86.

[0092] For example, in step S6, the adjuster 8c executes a moisture content derivation process, an impedance derivation process, and a current derivation process.

[0093] The moisture amount derivation process is a process for deriving the surrounding moisture amount, which is the amount of moisture around the voltage output board 86, in accordance with the detected humidity H1 and the detected temperature T1.

[0094] The impedance derivation process is a process for deriving an estimated impedance based on preset impedance characteristic information and the surrounding moisture amount. The impedance characteristic information represents the correspondence relationship between the surrounding moisture amount and the impedance of the voltage output board 86.

[0095] The current derivation process is a process for deriving an estimated leakage current Id20 in accordance with the development bias voltage VD1 in the current voltage-on state and the estimated impedance.

[0096] Note that leakage current characteristic information indicating the correspondence relationship between the development bias voltage VD1 and the estimated leakage current Id20 for each of the plurality of ranges of the peripheral moisture content may be set in advance. In this case, the adjuster 8c derives the estimated leakage current Id20 based on the derivation result of the peripheral moisture content and the leakage current characteristic information.

[0097] After performing the process of step S6, the adjuster 8c performs the process of step S7.

[0098] <Process S7> In step S7, the adjuster 8c acquires the total current Id4, which is the current detected by the current detection circuit 73 in the current voltage ON state.

[0099] After performing the process of step S7, the adjuster 8c performs the process of step S8.

[0100] <Process S8> In step S8, the adjuster 8c determines whether the dark current Id1, the estimated leakage current Id20, and the total current Id4 satisfy the target conditions.

[0101] In this embodiment, the target condition is that the sum of the dark current Id1 and the estimated leakage current Id20 matches the total current Id4 within the tolerance range.

[0102] The target condition indicates that the surface potential of the photosensitive member 41 is approximately equal to the developing bias voltage VD1. When the target condition is met, the toner image having an appropriate density is formed on the surface of the photosensitive member 41.

[0103] If it is determined that the dark current Id1, the estimated leakage current Id20, and the total current Id4 do not satisfy the target conditions, the adjuster 8c executes the process of step S9.

[0104] On the other hand, when it is determined that the dark current Id1, the estimated leakage current Id20, and the total current Id4 satisfy the target conditions, the adjuster 8c executes the process of step S10.

[0105] <Process S9> In step S9, the adjusting section 8c changes one or both of the developing bias voltage VD1 and the charging voltage VC1 according to the difference between the total current Id4 and the sum of the dark current Id1 and the estimated leakage current Id20.

[0106] Here, the sum of the dark current Id1 and the estimated leakage current Id20 is referred to as the total current. When the total current Id4 is greater than the total current, the adjustment unit 8c decreases the developing bias voltage VD1. On the other hand, when the total current Id4 is smaller than the total current, the adjustment unit 8c increases the developing bias voltage VD1.

[0107] The adjuster 8c may change the charging voltage VC1 in step S304. In this case, when the total current Id4 is greater than the total current, the adjuster 8c increases the charging voltage VC1. On the other hand, when the total current Id4 is smaller than the total current, the adjuster 8c decreases the charging voltage VC1.

[0108] The adjusting section 8c may also change the developing bias voltage VD1 within an allowable adjustment range, and change the charging voltage VC1 when the developing bias voltage VD1 is at the upper limit level or the lower limit level of the allowable adjustment range.

[0109] The processing in steps S3 to S4 and step S9 is an example of output control that causes the charging voltage output circuit 71 and the developing voltage output circuit 72 to output the charging voltage VC1 and the developing bias voltage VD1.

[0110] After performing the process of step S9, the adjuster 8c performs the processes of steps S5 to S8 again.

[0111] That is, the adjusting unit 8c adjusts one or both of the developing bias voltage VD1 and the charging voltage VC1 so that the dark current Id1, the estimated leakage current Id20, and the total current Id4 satisfy the target conditions (steps S3 to S9).

[0112] <Process S10> In step S10, the adjusting section 8c sets the levels of the developing bias voltage VD1 and the charging voltage VC1 when the target conditions are met as the adjusted reference levels, respectively.

[0113] After executing the process of step S10, the adjusting unit 8c ends the voltage adjusting process.

[0114] By performing the voltage adjustment process, the adjustment section 8c can appropriately adjust the charging voltage VC1 or the developing bias voltage VD1 based on the detection result of the current flowing through the transmission path of the developing bias voltage VD1.

[0115] When the job control unit 8b causes the printing device 4 to execute the printing process, it causes the charging voltage output circuit 71 and the developing voltage output circuit 72 to output the charging voltage VC1 and the developing bias voltage VD1 at the levels set in step S10.

[0116] [Variations] Below, modifications of the image forming apparatus 10 will be described.

[0117] In this modification, the image forming apparatus 10 includes a humidity sensor instead of the temperature and humidity sensor 74. The humidity sensor is an example of a humidity detection unit that detects the humidity inside the image forming apparatus 10.

[0118] <Process S5> The adjustment unit 8c in this application example acquires the detected humidity H1 detected by the humidity sensor in step S5 of the voltage adjustment process.

[0119] <Process S6> In this application example, in step S6 of the voltage adjustment process, the adjustment unit 8c derives the estimated leakage current Id20 according to the detected humidity H1 and the current developing bias voltage VD1 in the voltage ON state.

[0120] In this application example, the adjuster 8c derives the estimated leakage current Id20 by using the detected humidity H1 as an alternative index value for the ambient moisture amount.

[0121] For example, the adjuster 8c derives the estimated impedance in accordance with preset impedance characteristic information and the detected humidity H1. The impedance characteristic information in this application example represents the correspondence relationship between humidity and the impedance of the voltage output board 86.

[0122] Furthermore, the adjusting section 8c derives an estimated leakage current Id20 according to the developing bias voltage VD1 in the current voltage-on state and the estimated impedance.

[0123] Note that leakage current characteristic information indicating the correspondence relationship between the development bias voltage VD1 and the estimated leakage current Id20 for each of a plurality of humidity ranges may be set in advance. In this case, the adjuster 8c derives the estimated leakage current Id20 according to the detected humidity H1 and the leakage current characteristic information.

[0124] When this application example is adopted, the same effects as when the image forming apparatus 10 is adopted can be obtained.

[0125] [Notes on the Invention] The following is a summary of the invention extracted from the above-described embodiment. Note that the configurations and processing functions described in the following supplementary notes can be selected and combined as desired.

[0126] <Appendix 1> An image formation control method for controlling an image forming apparatus, comprising: the image forming apparatus, A photoreceptor; a charging device that charges the surface of the photoreceptor; a developing device having a developer body that is disposed opposite to the surface of the photosensitive member and carries toner, and that supplies the toner from the developer body to the photosensitive member; a voltage output board including a voltage output circuit that outputs a charging voltage to the charging device and a developing bias voltage to the developing body, and a current detection circuit that detects a current flowing in a developing bias transmission path that transmits the developing bias voltage; a humidity detection unit for detecting humidity inside the image forming apparatus, a control device executing non-output control that causes the voltage output circuit not to output the charging voltage and the developing bias voltage; the control device stores a dark current that is a current detected by the current detection circuit when the non-output control is being executed; the control device executes output control to cause the voltage output circuit to output the charging voltage and the developing bias voltage; The control device acquires the humidity detected by the humidity detection unit when the output control is being executed; the control device deriving an estimated leakage current in accordance with the detected humidity and the developing bias voltage when the output control is being executed; and the control device adjusts one or both of the charging voltage and the developing bias voltage in the output control so that the dark current, the estimated leakage current, and a total current, which is a current detected by the current detection circuit when the output control is being executed, satisfy target conditions.

[0127] <Appendix 2> When the image forming apparatus includes a temperature detection unit that detects the temperature inside the image forming apparatus, The control device further includes acquiring a detected temperature of the temperature detection unit when the output control is being executed, The image formation control method according to claim 1, wherein the control device derives the estimated leakage current according to the detected humidity, the detected temperature, and the developing bias voltage when the output control is being executed.

[0128] <Appendix 3> The control device deriving the estimated leakage current comprises: the control device deriving a surrounding moisture amount, which is the amount of moisture around the voltage output board, in accordance with the detected humidity and the detected temperature; the control device deriving an estimated impedance according to the surrounding moisture amount and impedance characteristic information that indicates a correspondence relationship between the surrounding moisture amount and the impedance of the voltage output board; 3. The image formation control method according to claim 2, further comprising: deriving the estimated leakage current according to the developing bias voltage and the estimated impedance when the output control is being executed.

[0129] <Appendix 4> The image formation control method according to any one of Supplementary Note 1 to Supplementary Note 3, wherein the target condition is a condition that the sum of the dark current and the estimated leakage current matches the total current within an allowable error range.

[0130] <Appendix 5> A photoreceptor; a charging device that charges the surface of the photoreceptor; a developing device having a developer body that is disposed opposite to the surface of the photosensitive member and carries toner, and that supplies the toner from the developer body to the photosensitive member; a voltage output board including a voltage output circuit that outputs a charging voltage to the charging device and a developing bias voltage to the developing body, and a current detection circuit that detects a current flowing in a developing bias transmission path that transmits the developing bias voltage; a humidity detection unit that detects humidity inside the image forming apparatus; An image forming apparatus comprising: a control device that realizes the image formation control method according to any one of Supplementary Note 1 to Supplementary Note 4. [Explanation of symbols]

[0131] 4: Printing device 8: Control device 10: Image forming device 30: Sheet transport path 40: Optical scanning device 41: Photoreceptor 42: Charging device 43: Developing device 44: Transcription device 46: Fixing device 71: Charge voltage output circuit 72: Development voltage output circuit 73: Current detection circuit 74: Temperature and humidity sensor 421: Charged body 431: Developer

Claims

1. An image formation control method for controlling an image forming apparatus, comprising: the image forming apparatus, A photoreceptor; a charging device that charges the surface of the photoreceptor; a developing device having a developer body that is disposed opposite to the surface of the photosensitive member and carries toner, and that supplies the toner from the developer body to the photosensitive member; a voltage output board including a voltage output circuit that outputs a charging voltage to the charging device and a developing bias voltage to the developing body, and a current detection circuit that detects a current flowing in a developing bias transmission path that transmits the developing bias voltage; a humidity detection unit for detecting humidity inside the image forming apparatus, a control device executing non-output control that causes the voltage output circuit not to output the charging voltage and the developing bias voltage; the control device stores a dark current that is a current detected by the current detection circuit when the non-output control is being executed; the control device executes output control to cause the voltage output circuit to output the charging voltage and the developing bias voltage; The control device acquires the humidity detected by the humidity detection unit when the output control is being executed; the control device deriving an estimated leakage current in accordance with the detected humidity and the developing bias voltage when the output control is being executed; and the control device adjusts one or both of the charging voltage and the developing bias voltage during the output control so that the dark current, the estimated leakage current, and a total current, which is a current detected by the current detection circuit when the output control is being executed, satisfy target conditions.

2. When the image forming apparatus includes a temperature detection unit that detects the temperature inside the image forming apparatus, The control device further includes acquiring a detected temperature of the temperature detection unit when the output control is being executed, 2. The image formation control method according to claim 1, wherein the control device derives the estimated leakage current in accordance with the detected humidity, the detected temperature, and the developing bias voltage when the output control is being executed.

3. The control device deriving the estimated leakage current comprises: the control device deriving a surrounding moisture amount, which is the amount of moisture around the voltage output board, in accordance with the detected humidity and the detected temperature; the control device deriving an estimated impedance according to the surrounding moisture amount and impedance characteristic information that indicates a correspondence relationship between the surrounding moisture amount and the impedance of the voltage output board; 3. The image formation control method according to claim 2, further comprising: deriving the estimated leakage current in accordance with the developing bias voltage and the estimated impedance when the output control is being executed.

4. 4. The image formation control method according to claim 1, wherein the target condition is a condition that the sum of the dark current and the estimated leakage current matches the total current within an allowable error range.

5. A photoreceptor; a charging device that charges the surface of the photoreceptor; a developing device having a developer body that is disposed opposite to the surface of the photosensitive member and carries toner, and that supplies the toner from the developer body to the photosensitive member; a voltage output board including a voltage output circuit that outputs a charging voltage to the charging device and a developing bias voltage to the developing body, and a current detection circuit that detects a current flowing in a developing bias transmission path that transmits the developing bias voltage; a humidity detection unit that detects humidity inside the image forming apparatus; An image forming apparatus comprising: a control device that implements the image forming control method according to any one of claims 1 to 3.

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