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 path state switching device 74 selectively switches a specific path part leading from a current detection circuit 73 to a development body 431 in a developing bias transmission path to one of a connected state and an insulated state. A control device 8 executes first control for placing the specific path part in the insulated state and causing a voltage output circuit to output the developing bias voltage. The control unit 8 sets leak characteristic information on the basis of the current detected by the current detection circuit 73 when the first control is being executed. The control device 8 derives an estimate leak current in accordance with the developing bias voltage and the leak characteristic information. The control unit 8 adjusts one or both of the electrification voltage and the developing bias voltage so that a dark current, the estimate leak current, and a total current satisfy a target condition.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 first method for controlling an image forming apparatus. The image forming apparatus to which the first method is applied includes a photoconductor, a charging device, a developing device, a voltage output board, and a path state switching device. 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 path state switching device selectively switches a specific path portion in the developing bias transmission path from the current detection circuit to the developer between a connected state that electrically connects the specific path portion and an insulated state that electrically insulates the specific path portion. The first method includes a control device executing a first control that sets the specific path portion to the insulated state and causes the voltage output circuit to output the developing bias voltage. The first method further includes the control device setting leakage characteristic information representing a correspondence relationship between the developing bias voltage and the leakage current in the power output board based on the current detected by the current detection circuit when the first control is being executed. The first method further includes the control device executing a second control in which the voltage output circuit does not output the charging voltage and the developing bias voltage and the specific path section is connected. The first method further includes the control device storing a dark current, which is a current detected by the current detection circuit when the second control is being executed. The first method further includes the control device executing a third control in which the specific path section is connected and the voltage output circuit is caused to output the charging voltage and the developing bias voltage. The first method further includes the control device deriving an estimated leakage current, which is an estimate of the leakage current, based on the developing bias voltage and the leakage characteristic information when the third control is being executed.The first method further includes the control device adjusting one or both of the charging voltage and the developing bias voltage in the third control so that the dark current, the estimated leakage current, and the total current, which is the current detected by the current detection circuit when the third control is being executed, satisfy target conditions.

[0010] According to another aspect of the present invention, there is provided a second method for controlling an image forming apparatus. The image forming apparatus to which the second method is applied includes a rotating photoconductor, a charging device, a developing device having a rotating developer, and the voltage output board. The second method includes a control device executing a first control that stops the rotation of the photoconductor and the developer and causes the voltage output circuit to output the developing bias voltage. The second method further includes the control device setting leakage characteristic information representing a correspondence relationship between the developing bias voltage and a leakage current in the power output board based on a current detected by the current detection circuit when the first control is being executed. The second method further includes the control device executing a second control that rotates the photoconductor and the developer and does not cause the voltage output circuit to output the charging voltage and the developing bias voltage. The second method further includes the control device storing a dark current, which is a current detected by the current detection circuit when the second control is being executed. The second method further includes the control device executing a third control in which the specific path portion is connected and the voltage output circuit is caused to output the charging voltage and the developing bias voltage. The second method further includes the control device deriving an estimated leakage current that is an estimate of the leakage current based on the developing bias voltage and the leakage characteristic information when the third control is being executed. The second method further includes the control device adjusting one or both of the charging voltage and the developing bias voltage in the third control so that the dark current, the estimated leakage current, and a total current that is a current detected by the current detection circuit when the third control is being executed satisfy target conditions.

[0011] A first device, which is 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 path state switching device, and the control device that realizes the first method.

[0012] A second device, which is an image forming apparatus according to another aspect of the present invention, includes the photosensitive member that rotates, the charging device, the developing device having the developing body that rotates, the voltage output board, and the control device that realizes the second method. [Effects of the Invention]

[0013] 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]

[0014] [Figure 1] FIG. 1 is a diagram showing the configuration of an image forming apparatus according to the first embodiment. [Figure 2] FIG. 2 is a block diagram showing the configuration of a control device in the image forming apparatus according to the first embodiment. [Figure 3] FIG. 3 is a configuration diagram of a voltage output board in the image forming apparatus according to the first embodiment. [Figure 4] FIG. 4 is a flowchart showing an example of a procedure for pre-print processing in the image forming apparatus according to the first embodiment. [Figure 5] FIG. 5 is a flowchart showing an example of a procedure for setting leakage characteristics in the image forming apparatus according to the first embodiment. [Figure 6] FIG. 6 is a flowchart showing an example of a procedure for voltage adjustment processing in the image forming apparatus according to the first embodiment. [Figure 7] FIG. 7 is a configuration diagram of a voltage output board and a contact portion moving mechanism in an image forming apparatus according to the second embodiment. [Figure 8]FIG. 8 is a flowchart showing an example of a procedure for print pre-processing in the image forming apparatus according to the second embodiment. [Figure 9] FIG. 9 is a flowchart showing an example of a procedure for setting leakage characteristics in the image forming apparatus according to the second embodiment. [Figure 10] FIG. 10 is a configuration diagram of a voltage output board in an image forming apparatus according to the third embodiment. [Figure 11] FIG. 11 is a flowchart showing an example of a procedure for print pre-processing in the image forming apparatus according to the third embodiment. [Figure 12] FIG. 12 is a flowchart showing an example of a procedure for setting leakage characteristics in the image forming apparatus according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0015] 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.

[0016] [First embodiment] The image forming apparatus 10 according to the first 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.

[0017] [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.

[0018] 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.

[0019] 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 .

[0020] 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.

[0021] 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.

[0022] The toner image is an image formed using toner as a developer, and the toner is an example of the granular developer.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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 .

[0032] 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.

[0033] 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.

[0034] 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 .

[0035] 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.

[0036] 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.

[0037] 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 .

[0038] 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 .

[0039] 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.

[0040] 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.

[0041] The operation device 801 is a device that accepts operations by a person, and includes, for example, operation buttons and a touch panel.

[0042] 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.

[0043] [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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] The CPU 81 executes the computer programs to perform various data processing and control operations.

[0050] 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.

[0051] 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 .

[0052] [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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] The current detection circuit 73 detects the current flowing through the development bias transmission path that transmits the development bias voltage VD1.

[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 pre-print process described below.

[0071] [Switch circuit 74] The image forming apparatus 10 further includes a switch circuit 74 mounted on the voltage output board 86 (see FIG. 3). The switch circuit 74 electrically connects or insulates a specific path portion. The specific path portion is a portion of the development bias transmission path extending from the current detection circuit 73 to the developing body 431.

[0072] In the following description, a state in which the specific path portion is electrically connected by the switch circuit 74 is referred to as a connected state. Also, a state in which the specific path portion is electrically insulated by the switch circuit 74 is referred to as an insulated state.

[0073] The switch circuit 74 selectively switches the specific path portion between the connected state and the insulated state in accordance with a switch command SW1 received from the CPU 81.

[0074] For example, the switch circuit 74 is a relay that electrically cuts off the specific path portion when the switch command SW1 is an active signal. In this case, the specific path portion is connected to the b-contact of the relay.

[0075] The switch circuit 74 is used in the leakage characteristic setting process and is an example of a path state switching device that switches the state of the specific path portion.

[0076] The switch circuit 74 may be, for example, a circuit including a transistor instead of a relay.

[0077] [Print pre-processing] An example of the procedure for the pre-printing process will be described below with reference to the flowchart shown in FIG.

[0078] For example, every time a request for the printing process is made, the adjustment unit 8c executes the pre-printing process before the printing process is started.

[0079] The print pre-processing 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.

[0080] In the following description, S101, S102, ... represent identification codes of a plurality of steps in the pre-printing process. In the pre-printing process, the process of step S101 is executed first.

[0081] <Process S101> In step S101, the adjusting unit 8c executes a leakage characteristic setting process (see FIG. 5) to be described later. The leakage characteristic setting process is a process for setting leakage characteristic information that indicates the correspondence relationship between the development bias voltage VD1 and the leakage current Id2.

[0082] After performing the process of step S101, the adjuster 8c performs the process of step S102.

[0083] <Process S102> In step S102, 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.

[0084] 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.

[0085] After performing the process of step S102, the adjuster 8c performs the process of step S103.

[0086] <Process S103> In step S103, the adjuster 8c returns the specific path section to the connected state.

[0087] The processing in steps S102 and S103 is an example of second control in which the charging voltage output circuit 71 and the developing voltage output circuit 72 are not caused to output the charging voltage VC1 and the developing bias voltage VD1, and the specific path section is brought into the connected state.

[0088] After performing the process of step S103, the adjuster 8c performs the process of step S104.

[0089] <Process S104> In step S104, 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.

[0090] After performing the process of step S104, the adjuster 8c performs the process of step S105.

[0091] <Process S105> In step S105, the adjusting section 8c sets the levels of the charging voltage VC1 and the developing bias voltage VD1 to preset reference levels.

[0092] 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.

[0093] After performing the process of step S105, the adjuster 8c performs the process of step S106.

[0094] <Process S106> In step S106, 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.

[0095] By executing the process of step S105, charging voltage VC1 and developing bias voltage VD1 at the levels set in step S104 are output to charging member 421 and developing member 431, respectively.

[0096] After performing the process of step S106, the adjuster 8c performs the process of step S107.

[0097] <Process S107> In step S107, the adjusting unit 8c executes a voltage adjusting process (see FIG. 6) to be described later. The voltage adjusting process is a process for setting the level of the charging voltage VC1 and the level of the developing bias voltage VD1 employed in the printing process.

[0098] After executing the process of step S107, the adjustment unit 8c ends the pre-printing process.

[0099] 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 S106.

[0100] [Leakage characteristics setting process] Next, an example of the procedure for the leakage characteristic setting process will be described with reference to the flowchart shown in FIG.

[0101] In the following description, S201, S202, ... represent identification symbols of a plurality of steps in the leakage characteristic setting process. In the leakage characteristic setting process, step S201 is executed first.

[0102] <Process S201> In step S201, the adjustment unit 8c puts the specific path portion into the insulating state.

[0103] After performing the process of step S201, the adjuster 8c performs the process of step S202.

[0104] <Process S202> In step S202, the adjusting unit 8c sets the level of the charging voltage VC1 to the reference level. After performing the process of step S202, the adjusting unit 8c performs the process of step S203.

[0105] <Process S203> In step S203, the adjusting section 8c sets the level of the developing bias voltage VD1 to a predetermined first level.

[0106] After executing the process of step S203, the adjuster 8c executes the process of step S204.

[0107] <Process S204> In step S204, 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.

[0108] By executing the process of step S204, the charging voltage VC1 of the reference level and the developing bias voltage VD1 of the first level are output to the charging member 421 and the developing member 431, respectively.

[0109] The processing of steps S201 to S204 is an example of a first control for putting the specific path portion into the insulating state and causing the developing voltage output circuit 72 to output the developing bias voltage VD1.

[0110] In the following description, a state in which the charging voltage VC1 of the reference level and the developing bias voltage VD1 of the first level are output to the charged body 421 and the developing body 431, respectively, is referred to as a first voltage output state. After performing the process of step S204, the adjustment unit 8c performs the process of step S205.

[0111] <Process S205> In step S205, the adjuster 8c acquires the first leakage current Id21, which is the current detected by the current detection circuit 73 in the first voltage output state.

[0112] After executing the process of step S205, the adjuster 8c executes the process of step S206.

[0113] <Process S206> In step S206, the adjusting unit 8c changes the level of the developing bias voltage VD1 to a predetermined second level, whereby the developing bias voltage VD1 of the second level is output to the developing body 431.

[0114] In the following description, a state in which the charging voltage VC1 of the reference level and the developing bias voltage VD1 of the second level are output to the charged body 421 and the developing body 431, respectively, is referred to as a second voltage output state. After performing the process of step S206, the adjustment unit 8c performs the process of step S207.

[0115] After executing the process of step S206, the adjuster 8c executes the process of step S207.

[0116] <Process S207> In step S207, the adjusting unit 8c acquires the second leakage current Id22, which is the current detected by the current detecting circuit 73 in the second voltage output state.

[0117] The first leakage current Id21 and the second leakage current Id22 are currents detected by the current detection circuit 73 when the first control is being executed.

[0118] After executing the process of step S207, the adjuster 8c executes the process of step S208.

[0119] <Process S208> In step S208, the adjusting section 8c sets and stores the leakage characteristic information based on the first and second levels of the developing bias voltage VD1 and the first and second leakage currents Id21 and Id22.

[0120] For example, the adjusting unit 8c sets a linear equation or a lookup table for deriving the leakage current Id2 from the developing bias voltage VD1 as the leakage characteristics information. The adjusting unit 8c records the set leakage characteristics information in the secondary storage device 83.

[0121] After executing the process of step S208, the adjuster 8c ends the leakage characteristic setting process. The leakage characteristic information is used in the voltage adjustment process.

[0122] [Voltage regulation processing] Next, an example of the procedure of the voltage adjustment process will be described with reference to the flowchart shown in Fig. 6. The voltage adjustment process is executed in the voltage ON state (see steps S105 and S106 in Fig. 4).

[0123] In the following description, S301, S302, ... represent identification symbols of a plurality of steps in the voltage adjustment process. In the voltage adjustment process, step S301 is executed first.

[0124] <Process S301> In step S301, the adjusting unit 8c derives an estimated leakage current Id20 corresponding to the level of the developing bias voltage VD1 in the current voltage-ON state based on the leakage characteristic information.

[0125] After executing the process of step S301, the adjuster 8c executes the process of step S302.

[0126] <Process S302> In step S302, 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.

[0127] After executing the process of step S302, the adjuster 8c executes the process of step S303.

[0128] <Process S303> In step S303, the adjuster 8c determines whether the dark current Id1, the estimated leakage current Id20, and the total current Id4 satisfy the target conditions.

[0129] 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.

[0130] 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.

[0131] 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 S304.

[0132] 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 S305.

[0133] <Process S304> In step S304, 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.

[0134] 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.

[0135] 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.

[0136] 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.

[0137] The processing of steps S105, S103, S106 and S304 is an example of a third control that places the specific path section in the connected state and 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.

[0138] After executing the process of step S304, the adjuster 8c executes the processes of steps S301 to S303 again.

[0139] 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 S301 to S304).

[0140] <Process S305> In step S305, 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.

[0141] After executing the process of step S305, the adjusting unit 8c ends the voltage adjusting process.

[0142] By performing the pre-printing process, the adjusting 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.

[0143] [Second embodiment] Next, an image forming apparatus 10A according to a second embodiment will be described with reference to Figures 7 to 9. In Figure 7, the same components as those shown in Figure 3 are denoted by the same reference numerals.

[0144] The following describes the differences between image forming apparatus 10A and image forming apparatus 10.

[0145] The image forming apparatus 10A has a configuration in which the switch circuit 74 in the image forming apparatus 10 is replaced with a contact moving device 6 (see FIG. 7).

[0146] The contact moving device 6 selectively moves a contact portion 70, which forms part of the developing bias transmission path, to either a contact position or a separated position. The contact position is a position where the contact portion 70 contacts the developing body 431, and the separated position is a position where the contact portion 70 is separated from the developing body 431.

[0147] The contact moving device 6 selectively moves the contact portion 70 to one of the contact position and the separated position in accordance with a control command CT1 received from the CPU 81. The contact moving device 6 is an example of the path state switching device.

[0148] For example, a solenoid having an arm portion that supports the contact portion 70 is employed as the contact moving device 6.

[0149] [Print pre-processing] The print pre-processing in the image forming apparatus 10A is performed in a procedure in which step S103 in the print pre-processing shown in FIG. 4 is replaced with step S103a.

[0150] The processing of step S102 and steps S104 to S107 shown in Fig. 8 is the same as the processing of the same steps shown in Fig. 4. After performing the processing of steps S101 and S102, adjustment unit 8c of image forming apparatus 10A performs the processing of step S103a.

[0151] <Process S103a> In step S103a, the adjustment unit 8c causes the contact moving device 6 to perform a process of moving the contact portion 70 from the contact position to the separated position.

[0152] After performing the process of step S103a, the adjuster 8c performs the processes of steps S104 to S107.

[0153] [Leakage characteristics setting process] The leakage characteristics setting process in the image forming apparatus 10A is executed in a procedure in which step S201 in the leakage characteristics setting process shown in FIG. 5 is replaced with step S201a.

[0154] The processing in steps S202 to S208 shown in FIG. 9 is the same as the processing in the same steps shown in FIG.

[0155] <Process S201a> In step S201a, the adjustment unit 8c causes the contact moving device 6 to perform a process of moving the contact portion 70 from the contact position to the separated position.

[0156] After performing the process of step S201a, the adjuster 8c performs the processes of steps S202 to S208.

[0157] In the image forming apparatus 10A, the leakage characteristic information is set based on the first leakage current Id21 and the second leakage current Id22 obtained when the contact portion 70 is located at the separated position (steps S202 to S208).

[0158] The processing of steps S201a to S204 is an example of a first control for putting the specific path portion into the insulating state and causing the developing voltage output circuit 72 to output the developing bias voltage VD1.

[0159] The processing in steps S102 and S103a is an example of second control in which the charging voltage output circuit 71 and the developing voltage output circuit 72 are not caused to output the charging voltage VC1 and the developing bias voltage VD1, and the specific path portion is brought into the connected state.

[0160] When the image forming apparatus 10A is employed, the same effects as when the image forming apparatus 10 is employed can be obtained.

[0161] In the image forming apparatus 10A, the leakage characteristic information is set based on the first leakage current Id21 and the second leakage current Id22 obtained when the contact portion 70 is located at the separated position (steps S202 to S208).

[0162] [Third embodiment] Next, an image forming apparatus 10B according to a third embodiment will be described with reference to Figures 10 to 12. In Figure 10, the same components as those shown in Figure 3 are denoted by the same reference numerals.

[0163] The following describes the differences between image forming apparatus 10B and image forming apparatus 10.

[0164] Image forming apparatus 10B has a configuration in which switch circuit 74 is removed from image forming apparatus 10 (see FIG. 10).

[0165] [Print pre-processing] The print pre-processing in the image forming apparatus 10B is performed in a procedure in which step S103 in the print pre-processing shown in FIG. 4 is replaced with step S103b.

[0166] The processing of step S102 and steps S104 to S107 shown in Fig. 11 is the same as the processing of the same steps shown in Fig. 4. After performing the processing of steps S101 and S102, adjustment unit 8c of image forming apparatus 10B performs the processing of step S103b.

[0167] <Process S103b> In step S103b, the adjustment unit 8c rotates the photosensitive member 41 and the developing member 431.

[0168] After performing the process of step S103a, the adjuster 8c performs the processes of steps S104 to S107.

[0169] [Leakage characteristics setting process] The leakage characteristics setting process in the image forming apparatus 10B is executed in a procedure in which step S201 in the leakage characteristics setting process shown in FIG. 5 is replaced with step S201b.

[0170] The processing in steps S202 to S208 shown in FIG. 12 is the same as the processing in the same steps shown in FIG.

[0171] <Process S201b> In step S201b, the adjustment unit 8c stops the rotation of the photosensitive member 41 and the developing member 431.

[0172] After performing the process of step S201b, the adjuster 8c performs the processes of steps S202 to S208.

[0173] In the image forming apparatus 10B, the leakage characteristic information is set based on the first leakage current Id21 and the second leakage current Id22 obtained when the photoconductor 41 and the developing body 431 stop rotating (steps S202 to S208).

[0174] When the rotation of the photoconductor 41 and the developing body 431 is stopped, the toner is unlikely to act as a medium for current in the gap between the photoconductor 41 and the developing body 431. Therefore, when the rotation of the photoconductor 41 and the developing body 431 is stopped, the specific path portion is in a state close to the insulating state.

[0175] The processing of steps S201b to S204 is an example of a first control in which the rotation of photoconductor 41 and developing body 431 is stopped and developing voltage output circuit 72 is caused to output developing bias voltage VD1.

[0176] The processing in steps S102 and S103b is an example of second control in which the photosensitive member 41 and the developing member 431 are rotated, and the charging voltage output circuit 71 and the developing voltage output circuit 72 are not caused to output the charging voltage VC1 and the developing bias voltage VD1.

[0177] When the image forming apparatus 10B is employed, the same effects as when the image forming apparatus 10 is employed can be obtained.

[0178] [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.

[0179] <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; and a path state switching device that selectively switches between a connection state in which a specific path portion in the developing bias transmission path from the current detection circuit to the developing body is electrically connected and an insulation state in which the specific path portion is electrically insulated, a control device executing a first control for putting the specific path portion into the insulating state and causing the voltage output circuit to output the developing bias voltage; the control device sets leakage characteristic information that indicates a correspondence relationship between the developing bias voltage and the leakage current in the power output board based on the current detected by the current detection circuit when the first control is being executed; the control device executes second control to prevent the voltage output circuit from outputting the charging voltage and the developing bias voltage and to bring the specific path portion into the connected state; the control device stores a dark current that is a current detected by the current detection circuit when the second control is being executed; the control device executes a third control in which the specific path portion is connected and the voltage output circuit is caused to output the charging voltage and the developing bias voltage; the control device deriving an estimated leakage current that is an estimated value of the leakage current according to the developing bias voltage and the leakage characteristic information when the third control is being executed; and the control device adjusts one or both of the charging voltage and the developing bias voltage in the third 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 third control is being executed, satisfy target conditions.

[0180] <Appendix 2> An image formation control method for controlling an image forming apparatus, comprising: the image forming apparatus, A rotating photoreceptor; a charging device that charges the surface of the photoreceptor; a developing device having a developing body that is disposed opposite the surface of the photosensitive body and rotates while carrying toner, and that supplies the toner from the developing body to the charged surface of the photosensitive body; and 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 control device executing a first control to stop the rotation of the photosensitive member and the developing member and to cause the voltage output circuit to output the developing bias voltage; the control device sets leakage characteristic information that indicates a correspondence relationship between the developing bias voltage and the leakage current in the power output board based on the current detected by the current detection circuit when the first control is being executed; the control device executes second control to rotate the photosensitive member and the developing member and not to cause the voltage output circuit 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 second control is being executed; the control device executes a third control in which the specific path portion is connected and the voltage output circuit is caused to output the charging voltage and the developing bias voltage; the control device deriving an estimated leakage current that is an estimated value of the leakage current according to the developing bias voltage and the leakage characteristic information when the third control is being executed; and the control device adjusts one or both of the charging voltage and the developing bias voltage in the third 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 third control is being executed, satisfy target conditions.

[0181] <Appendix 3> The image formation control method according to claim 1 or 2, wherein the target condition is a condition that the sum of the dark current and the estimated leakage current matches the total current within a range of an allowable error.

[0182] <Appendix 4> A photoreceptor; a charging device that charges the surface of the photoreceptor; a developing device having a developer carrying toner disposed opposite the surface of the photosensitive member, the developer supplying the toner from the developer to the charged surface of 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 path state switching device that selectively switches between a connection state in which the specific path portion in the development bias transmission path from the current detection circuit to the developer is electrically connected and an insulation state in which the specific path portion is electrically insulated; An image forming apparatus comprising: a control device that realizes the image forming control method described in Supplementary Note 1.

[0183] <Appendix 5> 5. The image forming apparatus according to claim 4, wherein the path state switching device is a switch circuit mounted on the voltage output board and electrically connects or insulates the developing bias transmission path.

[0184] <Appendix 6> The image forming apparatus described in Appendix 4, wherein the path state switching device is a contact moving device that selectively moves a contact portion that forms part of the development bias transmission path to either a position in contact with the developing body or a position spaced apart from the developing body.

[0185] <Appendix 7> A rotating photoreceptor; a charging device that charges the surface of the photoreceptor; a developing device having a developing body that is disposed opposite the surface of the photosensitive body and rotates while carrying toner, and that supplies the toner from the developing body to the charged surface of the photosensitive body; 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; An image forming apparatus comprising: a control device that realizes the image forming control method described in Supplementary Note 2. [Explanation of symbols]

[0186] 1: Housing 2: Sheet storage area 3: Sheet transport device 4: Printing device 4x: Image forming section 6: Contact moving device 8: Control device 8a: Main processing section 8b: Job control section 8c: Adjustment part 9: Sheet 10: Image forming device 10A: Image forming device 10B: Image forming device 30: Sheet transport path 40: Optical scanning device 41: Photoreceptor 42: Charging device 43: Developing device 44: Transcription device 45: Drum cleaning device 46: Fixing device 70: Contact point 71: Charge voltage output circuit 72: Development voltage output circuit 73: Current detection circuit 74: Switch circuit 81: CPU 82:RAM 83 :Secondary storage device 84: Signal interface 85: Communication equipment 86: Voltage output board 101: Output tray 103a: Process 103b :Process 201a :Process 201b :Process 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; and a path state switching device that selectively switches between a connection state in which a specific path portion in the developing bias transmission path from the current detection circuit to the developing body is electrically connected and an insulation state in which the specific path portion is electrically insulated, a control device executing a first control for putting the specific path portion into the insulating state and causing the voltage output circuit to output the developing bias voltage; the control device sets leakage characteristic information that indicates a correspondence relationship between the developing bias voltage and a leakage current in the power output board based on a current detected by the current detection circuit when the first control is being executed; the control device executes second control to prevent the voltage output circuit from outputting the charging voltage and the developing bias voltage and to set the specific path portion in the connected state; the control device stores a dark current that is a current detected by the current detection circuit when the second control is being executed; the control device executes third control to set the specific path portion in the connected state and to cause the voltage output circuit to output the charging voltage and the developing bias voltage; the control device deriving an estimated leakage current that is an estimated value of the leakage current in accordance with the developing bias voltage and the leakage characteristic information when the third control is being executed; and the control device adjusts one or both of the charging voltage and the developing bias voltage in the third 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 third control is being executed, satisfy target conditions.

2. An image formation control method for controlling an image forming apparatus, comprising: the image forming apparatus, A rotating photoreceptor; a charging device that charges the surface of the photoreceptor; a developing device having a developing body that is disposed opposite the surface of the photosensitive body and rotates while carrying toner, and that supplies the toner from the developing body to the charged surface of the photosensitive body; and 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 control device executing a first control to stop the rotation of the photosensitive member and the developing member and to cause the voltage output circuit to output the developing bias voltage; the control device sets leakage characteristic information that indicates a correspondence relationship between the developing bias voltage and a leakage current in the power output board based on a current detected by the current detection circuit when the first control is being executed; the control device executes second control to rotate the photosensitive member and the developing member and not to cause the voltage output circuit 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 second control is being executed; the control device executes third control to set the specific path portion in the connected state and to cause the voltage output circuit to output the charging voltage and the developing bias voltage; the control device deriving an estimated leakage current that is an estimated value of the leakage current in accordance with the developing bias voltage and the leakage characteristic information when the third control is being executed; and the control device adjusts one or both of the charging voltage and the developing bias voltage in the third 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 third control is being executed, satisfy target conditions.

3. 3. 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.

4. A photoreceptor; a charging device that charges the surface of the photoreceptor; a developing device having a developer carrying toner disposed opposite the surface of the photosensitive member, the developer supplying the toner from the developer to the charged surface of 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 path state switching device that selectively switches between a connection state in which a specific path portion in the development bias transmission path from the current detection circuit to the developer is electrically connected and an insulation state in which the specific path portion is electrically insulated; An image forming apparatus comprising: a control device that implements the image forming control method according to claim 1.

5. 5. The image forming apparatus according to claim 4, wherein the path state switching device is a switch circuit mounted on the voltage output board and electrically connects or insulates the developing bias transmission path.

6. 5. The image forming apparatus according to claim 4, wherein the path state switching device is a contact moving device that selectively moves a contact portion that forms part of the development bias transmission path to either a position in contact with the developing body or a position spaced apart from the developing body.

7. A rotating photoreceptor; a charging device that charges the surface of the photoreceptor; a developing device having a developing body that is disposed opposite the surface of the photosensitive body and rotates while carrying toner, and that supplies the toner from the developing body to the charged surface of the photosensitive body; 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; An image forming apparatus comprising: a control device that implements the image forming control method according to claim 2.

Images