Static eliminating device, image forming system, and electric charge adjustment device

Abstract

To provide a static eliminating device, an image forming system, and an electric charge adjustment device that can apply a voltage to a static eliminating member in an appropriate method.SOLUTION: A static eliminating device comprises: a static eliminating member that is in contact with a sheet to eliminate static electricity from the sheet; voltage application means that applies a voltage to the static eliminating member; input means for inputting the value of the voltage applied by the voltage application means to the static eliminating member; control means that can execute a plurality of modes including a first mode for automatically changing the value of the voltage that the control means causes the voltage application means to output during execution of a job, and a second mode for causing the voltage application means to output the voltage on the basis of the value input through the input means without automatically changing the value of the voltage that the control means causes the voltage application means to output during execution of the job; and selection means for selecting a mode to be executed by the control means from the plurality of modes.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present invention relates to a static eliminator that eliminates static electricity from a sheet, an image forming system that forms an image on a sheet, and a charge adjusting device that adjusts the charge on the sheet. [Background technology]

[0002] Patent Document 1 describes a static elimination device that includes a static elimination roll, which is a contact-type static eliminator that comes into contact with paper, and a corotron-type static eliminator, which is a non-contact static eliminator that does not come into contact with paper. This document describes that the static elimination voltage to be applied to the static elimination roll is determined based on the surface potential of the paper that is actually measured using a surface potential meter (potential probe). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-167169 Summary of the Invention [Problem to be solved by the invention]

[0004] Since the task of measuring the surface potential of a sheet and adjusting the neutralization voltage can be a burden for the user, consideration was given to adding a function to automatically correct the neutralization voltage while a job is being executed. However, it is anticipated that there may be cases where the user does not want the neutralization voltage to be automatically corrected, or where the automatically corrected neutralization voltage value deviates from the appropriate value.

[0005] SUMMARY OF THE INVENTION An object of the present invention is to provide a static eliminator, an image forming system, and a charge adjusting device that are capable of applying a voltage to a static eliminator member in an appropriate manner. [Means for solving the problem]

[0006] One aspect of the present invention is a static elimination device comprising: a static elimination member that contacts a sheet and eliminates static electricity from the sheet; a voltage application means that applies a voltage to the static elimination member; an input means for inputting the value of the voltage that the voltage application means applies to the static elimination member; a control means that controls the voltage application means, the control means being capable of executing multiple modes including a first mode that automatically changes the value of the voltage that the voltage application means outputs during execution of a job in which the sheet is neutralized by the static elimination member while the sheet is being transported; and a second mode that outputs a voltage based on the value input via the input means without automatically changing the value of the voltage that the voltage application means outputs during execution of the job; and a selection means for selecting the mode that the control means is to execute from the multiple modes.

[0007] Another aspect of the present invention is a charge adjustment device comprising: a charge supply member that contacts a sheet and supplies a charge to the sheet; a voltage application means that applies a voltage to the charge supply member; an input means for inputting a value of the voltage that the voltage application means applies to the charge supply member; a control means that controls the voltage application means, the control means being capable of executing a plurality of modes including a first mode that automatically changes the value of the voltage that the voltage application means outputs during execution of a job in which the charge state of the sheet is adjusted by the charge supply member while the sheet is being transported; and a second mode that outputs a voltage based on a value input via the input means without automatically changing the value of the voltage that the voltage application means outputs during execution of the job; and a selection means for selecting a mode to be executed by the control means from the plurality of modes. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a static eliminator, an image forming system, and a charge adjusting device that are capable of applying a voltage to a static eliminator member in an appropriate manner. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram of an image forming system according to a first embodiment. [Figure 2] 1 is a schematic diagram of a static eliminator according to a first embodiment. [Figure 3] FIG. 2 is a schematic view of a conveying guide according to the first embodiment. [Figure 4] FIG. 2 is a diagram showing a static elimination operation unit according to the first embodiment. [Figure 5] FIG. 2 is a block diagram of a control system according to the first embodiment. [Figure 6] 4 is a flowchart showing a control method (automatic adjustment) according to the first embodiment. [Figure 7] FIG. 4 is a diagram showing an example of changes in static elimination current and static elimination voltage in Example 1. [Figure 8] 4 is a flowchart showing a control method (manual adjustment) according to the first embodiment. [Figure 9] FIG. 4 is an explanatory diagram for measuring the surface potential of a sample sheet. [Figure 10] 10A to 10D are diagrams showing examples of screen displays of the operation unit according to Example 1. FIG. [Figure 11] FIG. 10 is an explanatory diagram of control according to the environmental moisture content in the second embodiment. [Figure 12] FIG. 10 is an explanatory diagram of control according to the number of continuously fed sheets in the second embodiment. [Figure 13] FIG. 10 is a diagram showing an example of a screen display of an operation unit according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0011] Example 1 FIG. 1 shows a schematic diagram of an image forming system 400 according to a first embodiment. The image forming system 400 includes an image forming apparatus 100 (printer) and a static eliminator 300 connected to the image forming apparatus 100. The image forming system 400 forms an image on a sheet S and discharges it as a finished product (printed product). The sheet S, which is a recording material (recording medium), can be a variety of sheet materials of different sizes and materials, such as paper such as plain paper and cardboard, surface-treated sheet materials such as coated paper, specially shaped sheet materials such as envelopes and index paper, plastic sheet materials, cloth, etc. Examples of plastic sheet materials include synthetic paper made primarily of synthetic resin and overhead projector sheets (OHT).

[0012] The static eliminator 300 is a device (static eliminator) equipped with a static elimination function that removes (reduces) the charge on the sheet S discharged from the image forming system 400. The static eliminator 300 can also be considered a charge adjustment device that adjusts the charge state of the sheet S discharged from the image forming system 400. The static eliminator 300 may also be equipped with a function other than the static elimination function (for example, a decurler function that corrects curling of the sheet S). Furthermore, although the static eliminator 300 in this embodiment is disposed as a device independent of the image forming apparatus 100, the static eliminator 300 may also be incorporated into the housing of the image forming apparatus 100.

[0013] The image forming system 400 may include optional devices other than the static eliminator 300. Examples of the optional devices include a large-capacity feeding device (optional feeder) that supplies sheets S to the image forming apparatus 100, and a sheet processing device (finisher) that performs processing such as binding on sheets S on which images are formed by the image forming apparatus 100.

[0014] <Image forming device> 1 shows a schematic configuration of an image forming apparatus 100. The image forming apparatus 100 includes an image forming section 101, which is an intermediate transfer type electrophotographic mechanism. The image forming section 101 includes four process units 11Y, 11M, 11C, and 11K, each having a photosensitive drum 1Y, 1M, 1C, and 1K, and a transfer unit 15 having an intermediate transfer belt 6 and a secondary transfer roller 9.

[0015] Each process unit includes a photosensitive drum as an image carrier (latent image carrier) and a charging device, an exposure device, and a developing device as process units that act on the photosensitive drum to perform each step of the electrophotographic process. Specifically, process unit 11Y includes photosensitive drum 1Y, charging device 2Y, exposure device 3Y, and developing device 4Y. Process unit 11M includes photosensitive drum 1M, charging device 2M, exposure device 3M, and developing device 4M. Process unit 11C includes photosensitive drum 1C, charging device 2C, exposure device 3C, and developing device 4C. Process unit 11K includes photosensitive drum 1K, charging device 2K, exposure device 3K, and developing device 4K.

[0016] Each of the photosensitive drums 1Y, 1M, 1C, and 1K is rotated in a predetermined rotation direction A. The process units 11Y, 11M, 11C, and 11K have substantially the same configuration, except that the toners contained as developers in the developing devices 4Y, 4M, 4C, and 4K are different.

[0017] The transfer unit 15 includes an intermediate transfer belt 6 as an intermediate transfer body, a secondary transfer roller 9 as a transfer means (secondary transfer means), primary transfer rollers 5Y, 5M, 5C, and 5K, multiple rollers 20, 21, 22, 23, 24, and 25, and a belt cleaner 12. The intermediate transfer belt 6 is stretched over the multiple rollers 20, 21, 22, 23, 24, and 25. The primary transfer rollers 5Y, 5M, 5C, and 5K are disposed on the inner surface of the intermediate transfer belt 6 at positions corresponding to the photosensitive drums 1Y, 1M, 1C, and 1K, respectively. A primary transfer portion is formed between the primary transfer rollers 5Y, 5M, 5C, and 5K and the corresponding photosensitive drums 1Y, 1M, and 1C. Roller 20 is a tension roller that applies an appropriate tension to the intermediate transfer belt 6. Roller 22 is a drive roller that rotates the intermediate transfer belt 6 in a predetermined rotation direction G. The secondary transfer roller 9 is in contact with the outer surface of the intermediate transfer belt 6 and is disposed so as to sandwich the intermediate transfer belt 6 together with an opposing roller 21 (secondary transfer opposing roller). A secondary transfer portion T2 is formed as a nip portion between the secondary transfer roller 9 and the intermediate transfer belt 6, where a toner image is transferred onto the sheet S.

[0018] The image forming apparatus 100 includes a transfer power supply 10 as a voltage application means for forming a bias electric field at the secondary transfer portion T2 for transferring a toner image. In this embodiment, the secondary transfer roller 9, which is the outer roller of the secondary transfer portion T2, is electrically connected to the transfer power supply 10, and a predetermined transfer voltage is applied from the transfer power supply 10. The transfer voltage is a voltage of a polarity opposite to the normal charging polarity of the toner used in image formation. Meanwhile, the counter roller 21, which is the inner roller of the secondary transfer portion T2, is electrically connected to the ground potential (metal frame, etc.) of the image forming apparatus 100. Alternatively, the inner roller of the secondary transfer portion T2 may be connected to the transfer power supply 10, and the outer roller of the secondary transfer portion T2 may be connected to the ground potential GND. In this case, a transfer voltage of the same polarity as the normal charging polarity of the toner is applied to the inner roller.

[0019] The image forming apparatus 100 further has a storage section 63 (storage cabinet, cassette) that stores the sheet S, a feeding unit 64 that feeds the sheet S, and a registration roller 8 that registers (aligns) the sheet S. The image forming apparatus 100 also has a pre-fixing conveying device 41 that conveys the sheet S that has passed through the secondary transfer section T2, a fixing device 40 that fixes the toner image on the sheet S, and a pair of discharge rollers 42 as a discharge unit that discharges the sheet S to the outside of the image forming apparatus 100.

[0020] The feeding unit 64 includes, for example, a pickup roller 65 that feeds the top sheet S from the storage section 63 in the sheet feeding direction, and a separation roller pair 66 that separates and conveys the fed sheets S one by one. The separation roller pair includes a conveying roller that feeds the top sheet S in the sheet feeding direction, and a separation roller that abuts against the conveying roller and forms a separation nip together with the conveying roller. The separation roller applies friction to the sheet S at the separation nip, thereby preventing sheets S other than the top sheet S from passing through the separation nip, thereby preventing double feeding of sheets S. The separation roller is an example of a separating member that separates the sheets S, and a pad-shaped elastic member (rubber pad), for example, may be used as the separating member.

[0021] The fixing device 40 is a thermal fixing device that has a fixing nip and heats the toner image on the sheet S while sandwiching and transporting the sheet S in the fixing nip. The fixing device 40 has a heating member that contacts the surface of the sheet S on which the toner image is formed, a pressure member that forms the fixing nip together with the heating member, and a heat source that heats the heating member. The heating member and pressure member can be, for example, a belt member stretched over multiple rollers or a rigid roller member. The heat source can be, for example, a halogen lamp or an induction heating mechanism.

[0022] The image forming apparatus 100 also includes a user operation unit 102, which is a user interface for the image forming system 400. The user operation unit 102 has a display unit 102a, such as a liquid crystal panel, that displays information to the user, and an input unit, such as physical buttons and a touch panel function of the liquid crystal panel, that receives information input from the user. By operating the user operation unit 102, the user can set setting information and execution conditions for the image forming operation for the image forming system 400. The setting information is, for example, attribute information such as the size, material, and brand of the sheets S stored in the storage unit 63. The execution conditions for the image forming operation are, for example, the value of the transfer voltage.

[0023] When a user inputs an instruction to perform image formation, the control unit of the image forming apparatus 100 starts an image formation job, which is a series of tasks for forming an image on the sheets S while transporting them one by one and outputting a product. Hereinafter, a series of operations for forming an image on one sheet S by the image forming apparatus 100 will be referred to as an image forming operation. The image forming job includes an image forming operation on at least one sheet S.

[0024] During image formation, process units 11Y, 11M, 11C, and 11K create toner images of each color. Specifically, photosensitive drums 1Y, 1M, 1C, and 1K are rotated, and charging devices 2Y, 2M, 2C, and 2K uniformly charge the surfaces of photosensitive drums 1Y, 1M, 1C, and 1K. Exposure devices 3Y, 3M, 3C, and 3K expose photosensitive drums 1Y, 1M, 1C, and 1K to light based on image information input along with execution instructions, forming electrostatic latent images on the surfaces of photosensitive drums 1Y, 1M, 1C, and 1K. Developing devices 4Y, 4M, 4C, and 4K supply yellow, magenta, cyan, and black toner to photosensitive drums 1Y, 1M, 1C, and 1K, respectively, to develop the electrostatic latent images into toner images of each color.

[0025] In this embodiment, a reverse development method is used, in which the charging device charges the surface of the photosensitive drum to the same polarity as the normal charging polarity of the toner, and then the potential of the exposed area exposed by the exposure device is attenuated, and the toner adheres to the exposed area during development.

[0026] The toner images created in the process units 11Y, 11M, 11C, and 11K are primarily transferred from the photosensitive drums 1Y, 1M, 1C, and 1K to the intermediate transfer belt 6 in the primary transfer section. A transfer voltage of a polarity opposite to the normal charging polarity of the toner is applied to the primary transfer rollers 5Y, 5M, 5C, and 5K by constant voltage control.

[0027] In this embodiment, the primary transfer rollers 5Y, 5M, 5C, and 5K are conductive rollers having a core and a conductive elastic layer formed on the outer periphery of the core. The elastic layer is formed of, for example, ion-conductive foam rubber. Ion-conductive foam rubber is a foam rubber material in which a conductive agent that exhibits ion conductivity is dispersed. The conductive agent and the foam rubber material may be materials known for transfer rollers. Each primary transfer roller has, for example, an outer diameter of 15 to 20 mm, and a resistance of 1×10 when a voltage of 2 kV is applied under environmental conditions of 23°C and 50% RH. 5 ~1×10 8 Those having an Ω value can be preferably used.

[0028] The intermediate transfer belt 6 is rotated at a predetermined peripheral speed (process speed) equal to the peripheral speed of the photosensitive drums 1Y, 1M, 1C, and 1K. In this embodiment, the peripheral speed is 150 to 470 mm / sec. As the intermediate transfer belt 6 rotates, toner images of other colors are transferred onto the toner image transferred at the upstream primary transfer unit, thereby forming a full-color toner image on the intermediate transfer belt 6. The full-color toner image is carried on the intermediate transfer belt 6 and transported toward the secondary transfer unit T2.

[0029] In parallel with the creation of the toner image in the image forming unit 101, the feeding unit 64 feeds the sheets S one by one toward the image forming unit 101. The fed sheets S are transported to the secondary transfer unit T2 by the registration rollers 8 in synchronization with the timing at which the toner image on the intermediate transfer belt 6 is transported to the secondary transfer unit T2. Then, at the secondary transfer unit T2, the toner image is transferred (secondary transfer) from the intermediate transfer belt 6 to the sheet S.

[0030] In this embodiment, the secondary transfer roller 9 is a conductive roller having a core and a conductive elastic layer formed on the outer periphery of the core. The elastic layer is formed of, for example, ion-conductive foam rubber. The ion-conductive foam rubber is a foam rubber material in which a conductive agent that exhibits ion conductivity is dispersed. The conductive agent and the foam rubber material may be materials known for transfer rollers. The secondary transfer roller 9 has, for example, an outer diameter of 20 to 25 mm, and a resistance of 1×10 when a voltage of 2 kV is applied under environmental conditions of 23°C and 50% RH. 5 ~1×10 8 Those having an Ω value can be preferably used.

[0031] The opposing roller 21 is a conductive roller having a core and an elastic layer of electronically conductive foamed rubber formed on the outer periphery of the core. The electronically conductive foamed rubber is a foamed rubber material in which a conductive agent that exhibits electronic conductivity is dispersed. The conductive agent and the foamed rubber material may be materials known for transfer rollers. The opposing roller 21 may have an outer diameter of 20 to 22 mm, for example, and a resistance of 1×10 when a voltage of 50 V is applied under environmental conditions of 23°C and 50% RH. 5 ~1× 8 Those having an Ω value can be preferably used.

[0032] During secondary transfer, a transfer voltage of opposite polarity to the normal charging polarity of the toner is applied to the secondary transfer roller 9 from a transfer power supply 10 under constant voltage control. The transfer voltage is, for example, +1 to +7 kV, and is automatically adjusted so that a current of +40 to +120 μA flows from the secondary transfer roller 9 to the opposing roller 21. The application of the transfer voltage forms a bias electric field at the secondary transfer portion T2, such that the potential of the secondary transfer roller 9 has a polarity opposite to the normal charging polarity of the toner relative to the intermediate transfer belt 6. This bias electric field acts on the toner on the intermediate transfer belt 6 with an electrostatic force in a direction that draws it closer to the secondary transfer roller 9. The toner is then transferred from the intermediate transfer belt 6 to the sheet S passing through the secondary transfer portion T2, thereby transferring a toner image onto the sheet S.

[0033] Incidentally, a conveying guide 11 is provided immediately before the secondary transfer portion T2 to improve the positional accuracy of the sheet S with respect to the intermediate transfer belt 6. Furthermore, residual toner that is not transferred to the sheet S and remains on the intermediate transfer belt 6 is collected by a belt cleaner 12 and reused for image formation.

[0034] After passing through the secondary transfer portion T2, the sheet S is transported to the fixing device 40 by the pre-fixing conveying device 41, where the toner image is fixed by the fixing device 40. The fixing process involves heating and pressurizing the toner image on the sheet S while the sheet S is nipped and transported in the nip of the fixing device 40. The pre-fixing conveying device 41 transports the sheet S, for example, on an endless rubber belt. The rubber belt may be made of ethylene propylene diene rubber (EPDM) and have a width of 100 to 110 mm and a thickness of 1 to 3 mm. The rubber belt has holes with a diameter of 3 to 7 mm, and a fan is used to generate negative pressure inside the rubber belt, allowing the sheet S to be stably supported on the rubber belt.

[0035] The sheet S that has passed through the fixing device 40 is discharged toward the static eliminator 300 by a pair of discharge rollers 42.

[0036] The intermediate transfer type image forming unit 101 described above is an example of an image forming means that forms an image on a sheet S, and the image forming means may be, for example, a direct transfer type electrophotographic unit. In this case, a toner image formed on a photosensitive drum serving as an image carrier is directly transferred from the photosensitive drum to the sheet S at a transfer nip (transfer portion) where the photosensitive drum and a transfer roller face each other. At the transfer nip, a bias electric field is formed in which the potential of the transfer roller has a polarity opposite to the normal charging polarity of the toner relative to the photosensitive drum.

[0037] <Static eliminator> 2 is a schematic diagram of a static eliminator 300 in the first embodiment. In this embodiment, the static eliminator 300 is connected downstream of the image forming apparatus 100. The static eliminator 300 receives the sheet S on which an image has been formed by the image forming apparatus 100 and conveys the sheet S in the sheet conveying direction Cv while eliminating static from the sheet S (reducing static charge on the sheet surface). By eliminating static from the sheet S, it is possible to prevent stacked sheets discharged from the image forming system 400 from sticking to each other due to electrostatic attraction, and to prevent deterioration in the integrity of the sheets S due to the sheets sticking to each other. The static eliminator 300 includes a pair of static eliminators 51 as a contact static eliminator and an ionizer unit 52 as a non-contact static eliminator.

[0038] The discharge roller pair 51 includes a discharge opposing roller 51a that contacts the first surface Sa of the sheet S, and a discharge roller 51b that contacts the second surface Sb of the sheet S opposite the first surface Sa. The discharge roller 51b is a contact-type discharge member that contacts the sheet S being conveyed and discharges the sheet S. The discharge opposing roller 51a abuts against the discharge roller 51b, and a discharge nip is formed as a nip portion between the discharge roller 51b and the discharge opposing roller 51a. The discharge roller pair 51 discharges the sheet S while nipping the sheet S in the discharge nip and conveying it.

[0039] The discharge opposing roller 51a is connected to the ground potential GND. The discharge opposing roller 51a is electrically connected to, for example, a metal frame of the discharge device 300 and is electrically grounded. The discharge roller 51b is connected to a high-voltage power supply 55. The high-voltage power supply 55 is a voltage application means that applies a voltage (discharge voltage) to the discharge roller 51b to discharge the sheet S.

[0040] The discharge roller 51b may be disposed so as to contact the first surface Sa of the sheet S, and the discharge opposing roller 51a may be disposed so as to contact the second surface Sb of the sheet S. In this case, the voltage applied to the discharge roller 51b has a polarity opposite to that of the voltage applied to the discharge roller 51b in this embodiment.

[0041] In this embodiment, the static elimination roller 51b is a conductive roller having a core and a conductive elastic layer formed on the outer periphery of the core. The elastic layer is made of, for example, ion-conductive foam rubber. The ion-conductive foam rubber is a foam rubber material in which a conductive agent that exhibits ion conductivity is dispersed. Known materials can be used for the conductive agent and the foam rubber material. The static elimination roller 51b has, for example, an outer diameter of 20 to 25 mm and a resistance of 1×10 when a voltage of 2 kV is applied under environmental conditions of 23°C and 50% RH. 5 ~1×10 8 An Ω-type roller can be suitably used. The counter static elimination roller 51a is made of stainless steel (SUS) and has an outer diameter of 20 to 25 mm. Note that the static elimination roller 51b may also be a roller made of a metal such as stainless steel.

[0042] The ionizer unit 52 includes a first ionizer 52a facing the first surface of the sheet S and a second ionizer 52b facing the second surface of the sheet S. Each of the first ionizer 52a and the second ionizer 52b has an electrode needle, and by applying a voltage to the electrode needle, a corona discharge is generated from the tip of the needle, ionizing the air around the tip of the needle. The generated ions then neutralize the charge on the surface of the sheet S, thereby de-electrifying the sheet S.

[0043] In this embodiment, the ionizer unit 52 is configured with bar-type ionizers IZS40 (manufactured by SMC Corporation) as the first ionizer 52a and the second ionizer 52b, which are arranged above and below the sheet transport path. The transport guides 53a and 53b that form the sheet transport path of the ionizer unit 52 are made of a resin obtained by compounding PC (polycarbonate) and ABS (acrylonitrile-butadiene-styrene), for example. The volume resistivity of the transport guides 53a and 53b is, for example, 1×10 14 3, each of the conveying guides 53a and 53b has a plurality of holes 530 formed therein to prevent the ions emitted from the first ionizer 52a and the second ionizer 52b from being physically blocked. The holes 530 are arranged in a line in the sheet width direction perpendicular to the sheet conveying direction Cv.

[0044] The first ionizer 52a and the second ionizer 52b described above are examples of non-contact static eliminators, and other non-contact static eliminators may be used. For example, a corotron or scorotron static eliminator that eliminates static electricity from a sheet by corona discharge from a discharge wire may be used. Furthermore, the non-contact static eliminators do not necessarily need to be provided on both sides of the conveyance path. For example, the static eliminator 300 may be configured to have only the first ionizer 52a as a non-contact static eliminator. Furthermore, if the static eliminator roller 51b can sufficiently eliminate static electricity from the sheet S, the non-contact static eliminator may be omitted.

[0045] The sheet S conveyed from the image forming apparatus 100 to the static eliminator 300 first has most of the charge removed (roughly removed) in the static elimination nip of the static elimination roller pair 51. Specifically, the static elimination voltage is set to have the opposite polarity to the transfer voltage applied to the secondary transfer roller 9. The value of the static elimination voltage is set in the range of -1 kV to -6 kV.

[0046] At the secondary transfer portion T2 (FIG. 1), the sheet S is typically charged so that the first side Sa of the sheet S, which has been in contact with the intermediate transfer belt 6, becomes negatively charged and the second side Sb of the sheet S, which has been in contact with the secondary transfer roller 9, becomes positively charged. When a discharge voltage of a polarity opposite to the transfer voltage is applied to the discharge roller 51b, a current flows between the discharge roller 51b and the discharge opposing roller 51a so that a positive charge is supplied to the first side Sa of the sheet S and a positive charge is supplied to the second side Sb of the sheet S. In this way, the application of a discharge voltage to the discharge roller 51b causes a current to flow through the sheet S at the discharge nip, thereby reducing the amount of charge carried on the first side Sa and the second side Sb of the sheet S.

[0047] The sheet S that has passed through the pair of charge-removing rollers 51 is further neutralized in the ionizer unit 52. Specifically, the charges remaining on the first surface Sa and the second surface Sb of the sheet S are neutralized by ions emitted from the first ionizer 52a and the second ionizer 52b, thereby further reducing the amount of charge on the sheet S. The sheet S that has passed through the ionizer unit 52 is discharged outside the charge removal device 300.

[0048] The amount of charge on the sheet S is usually proportional to the surface potential of the sheet S. The amount of charge on the sheet S may be expressed as the amount of charge per unit area of the sheet surface (surface charge density). Therefore, the "amount of charge" on the sheet S in the following description may be replaced with the surface potential or the surface charge density of the sheet S.

[0049] <Static elimination voltage adjustment switch> The static eliminator 300 is provided with a static elimination operation unit 54 that can be operated to change the operating conditions of the static eliminator 300. An enlarged view of the static elimination operation unit 54 is shown in Fig. 4. The static elimination operation unit 54 is an example of input means that allows a user to input the value of the voltage that the high-voltage power supply 55 (voltage application means) applies to the static elimination roller 51b (static elimination member).

[0050] The static elimination operation unit 54 includes a changeover switch 54a and a voltage adjustment switch 54b. By operating the changeover switch 54a, the user can switch between outputting (ON) and stopping (OFF) the static elimination voltage from a high-voltage power supply 55 (FIG. 2) that applies the static elimination voltage to the static elimination roller 51b. The voltage adjustment switch 54b allows the user to adjust the value of the static elimination voltage.

[0051] The value of the neutralization voltage can also be fixed at a value that is preset according to the category of the sheet S. For example, it is known that plastic film or synthetic paper undergoes stronger dielectric polarization at the secondary transfer unit than plain paper, and the amount of electrostatic charge on the sheet S is likely to be large. Therefore, when using plastic film or synthetic paper as the sheet S, it is possible to set the neutralization voltage value in advance according to the category of the sheet S so that the neutralization voltage is higher (the absolute value is larger) than when using plain paper as the sheet S. However, even for sheets S of the same category, there are cases where the appropriate neutralization voltage value varies due to differences in electrical resistance caused by differences in the specific materials, differences in thickness, differences in usage environment, etc. Therefore, in this embodiment, the neutralization voltage value is configured to be adjustable.

[0052] The voltage adjustment switch 54b of this embodiment includes a display unit that displays the value of the static elimination voltage in two digits, and buttons (+ button and - button) for increasing or decreasing the value of the static elimination voltage. Pressing the + button increases the number in the corresponding digit, and pressing the - button decreases the number in the corresponding digit.

[0053] The value displayed on the display is the absolute value of the static elimination voltage, displayed as a two-digit number in 0.1 kV increments. In other words, the set value of the static elimination voltage is obtained by multiplying the value displayed on the display of the voltage adjustment switch 54b by -0.1 kV. For example, if "45" is displayed on the display of the voltage adjustment switch 54b, the set value of the static elimination voltage is -4.5 kV. From this state, if the - button for the tens digit is pressed once and the + button for the ones digit is pressed twice, the display will change to "37" and the value of the static elimination voltage will be set to -3.7 kV.

[0054] When the voltage adjustment switch 54b is set to "00," the set value of the static elimination voltage becomes 0V (0.0 kV). In this case, the state of the high-voltage power supply 55 becomes the same as when the selector switch 54a is turned OFF. This state can also be said to be a state in which the first high-voltage power supply 55 applies 0V to the static elimination roller 51b.

[0055] The display and input methods for the value of the static elimination voltage are not limited to those described above. Instead of displaying the first two digits of the value of the static elimination voltage, the value itself may be displayed, or a numerical value representing the level of the static elimination voltage, for example, in ten stages, may be displayed. The value of the static elimination voltage may be displayed, for example, on the user operation unit 102 or on the screen of an external computer communicatively connected to the image forming system 400. The static elimination voltage value may be input by providing a numeric keypad on the static elimination operation unit 54 for inputting numerical values, by operating a touch panel on the user operation unit 102, or by receiving input via an external computer. The user operation unit 102, which can display a screen for inputting the static elimination voltage, is another example of an input unit for a user to input the value of the voltage to be applied by the high-voltage power supply 55 (voltage application means) to the static elimination roller 51b (static elimination member).

[0056] <Factors that affect the appropriate static elimination voltage> However, when voltage is continuously applied to the static elimination roller 51b, the resistance value of the static elimination roller 51b may change. For example, if a conductive roller containing an ionically conductive agent is used as the static elimination roller 51b as in this embodiment, the distribution of the conductive agent within the roller may become uneven due to continuous current application, causing the resistance value to change. In this case, if the static elimination voltage set via the static elimination operation unit 54 continues to be used at a value before the resistance value of the static elimination roller 51b changed, the change in the resistance value of the static elimination roller 51b may prevent the static elimination roller 51b from properly eliminating static electricity from the sheet S. In other words, the change in the resistance value of the static elimination roller 51b affects the charge supply capacity of the static elimination roller 51b to the sheet S, which may result in an excess or deficiency of the amount of charge actually supplied compared to the amount of charge required to eliminate static electricity from the sheet S.

[0057] Furthermore, the value of the transfer voltage applied to the secondary transfer portion T2 and the resistance value (ease of charge accumulation on the sheet surface) of the sheet S change depending on the environmental conditions (particularly temperature and humidity) of the environment in which the static elimination device 300 is installed. For this reason, the amount of charge actually supplied may be either excessive or insufficient compared to the amount of charge required to eliminate static electricity from the sheet S.

[0058] <Automatic correction of static elimination voltage> In this embodiment, in order to deal with the possibility that the neutralization capacity of the neutralization roller 51b may be insufficient or excessive due to factors such as those described above, a feedback control function (automatic correction function) is provided to automatically correct the neutralization voltage during job execution.

[0059] 5 shows a block diagram of the control circuit 200 related to the control of the static elimination voltage. The control circuit 200 is an example of a control means for controlling the operation of the static eliminator 300. The control circuit 200 may be mounted in the main body of the static eliminator 300, or some or all of the functions of the control circuit 200 may be mounted in the image forming apparatus 100.

[0060] As shown in FIG. 5, the control circuit 200 includes a CPU 201, a RAM 210, and a ROM 220. The CPU 201 is an execution unit that reads and executes a control program. The RAM 210 serves as a workspace for the CPU 201 when executing the control program. The ROM 220 is an example of a storage unit that stores various information, such as setting information related to the control of the static eliminator 300. The control circuit 200 is also connected to the user operation unit 102, the static elimination operation unit 54, the high-voltage power supply 55, and the transfer power supply 10. The high-voltage power supply 55 includes a current detection circuit 55a that detects the current supplied from the high-voltage power supply 55 to the static elimination roller 51b. The current detection circuit 55a functions as a current detection unit that detects the current flowing through the static elimination roller 51b (static elimination member).

[0061] The CPU 201 acquires information related to the image forming job (job information), the set value of the static elimination voltage, the value of the current (called static elimination current) that flows through the static elimination roller 51b when the static elimination voltage is applied, the value of the transfer voltage output by the transfer power supply 10, and other information, and stores the information in the RAM 210. Here, the job information refers to, for example, attribute information of the sheet S input by the user via the user operation unit 102, i.e., the attribute information of the sheet S used in the current image forming job. The set value of the static elimination voltage is a value set by the user through the static elimination operation unit 54. The value of the static elimination current is a value detected by the current detection circuit 55a. While the sheet S is passing through the static elimination nip (during paper passage), the value of the static elimination current corresponds to the amount of charge supplied from the static elimination roller 51b to the sheet S per unit time. The CPU 201 calculates a corrected static elimination voltage based on the information stored in the RAM 210 and control conditions (described later) stored in the ROM 220, and performs feedback control to control the output of the high-voltage power supply 55 based on the corrected static elimination voltage.

[0062] The control circuit 200 is also connected to an environment sensor 13 for detecting the environmental conditions of the installation environment (the space surrounding the installation of the static elimination device 300 (image forming system 400). Control using the environment sensor 13 will be described in Example 2. The ROM 220 also stores control parameters and various tables used to control the static elimination voltage.

[0063] The procedure for controlling the static elimination voltage performed by the control circuit 200 will be described with reference to the flowchart of Fig. 6. Hereinafter, the CPU 201 executes each step of this flow unless otherwise specified.

[0064] The process of this flow starts when an image formation job is input to the image forming system 400. First, the CPU 201 checks whether the setting method of the static elimination voltage is one of the three modes (automatic correction, manual setting, or media setting) that can be executed by the image forming apparatus 100 of this embodiment (S0).

[0065] The automatic correction mode is an example of a first mode in which the value of the voltage output by the high-voltage power supply 55 (voltage application means) is automatically changed during execution of a job. The manual setting mode and the media setting mode are both examples of a second mode in which the value of the voltage output by the high-voltage power supply 55 (voltage application means) is not automatically changed during execution of a job, but a voltage is output based on a value input via the static elimination operation unit 54 or the user operation unit 102 (input means).

[0066] As described above, in this embodiment, two control modes are provided as the second mode: a control mode in which the static elimination voltage is determined regardless of the sheet type (manual setting mode), and a control mode in which the static elimination voltage is determined based on the sheet type (media setting mode). However, the control circuit 200 may be configured to be able to execute one of a plurality of control modes, including at least one of the manual setting mode and the media setting mode.

[0067] (Manual setting mode) In the manual setting mode, the CPU 201 acquires the set value of the static elimination voltage that has been adjusted in advance by the user (Sa1). An example of the flow of adjusting the static elimination voltage by the user will be described later, but it is assumed that the adjusted set value has been stored in advance in a storage unit such as the RAM 210. In the manual setting mode, the static elimination voltage value that was set by the static elimination operation unit 54 before the start of the job is applied regardless of the type of sheet used in the job. The CPU 201 causes the high-voltage power supply 55 to output the static elimination voltage at the set value acquired in Sa1, and causes the static elimination roller 51b to neutralize the sheet S (Sa2).

[0068] The set value of the static elimination voltage can also be changed while a job is being executed. That is, if a user operates the voltage adjustment switch 54b of the static elimination operation unit 54 to change the set value of the static elimination voltage or switches the selector switch 54a ON / OFF while a job (continuous print job) is being executed to continuously form images on multiple sheets S, the CPU 201 continues the job based on the changed setting. In other words, in the manual setting mode, which is an example of the second mode, if the static elimination operation unit 54 (input means) is operated after the start of a job, the CPU 201 changes the value of the voltage to be output by the high-voltage power supply 55 (voltage application means) from the value input via the static elimination operation unit 54 before the start of the job to the value input via the static elimination operation unit 54 after the start of the job.

[0069] In Sa3, the CPU 201 determines whether the current sheet S is the final sheet in the image forming job, and if it is not the final sheet (Sa3N), the CPU 201 returns to Sa1 and repeats the same process for the subsequent sheet S. If the current sheet S is the final sheet (Sa3Y), the CPU 201 ends the process.

[0070] (Media setting mode) In the media setting mode, the CPU 201 acquires job information and confirms the type of sheet S to be used in the current job (Sb1). The CPU 201 then acquires a static elimination voltage setting value corresponding to the sheet S to be used in the current job from setting information (media information) preset for each sheet type (Sb2). While the user's setting of media information will be described later, it is assumed that media information, including the static elimination voltage setting value for each sheet type, is pre-stored in the RAM 210. The RAM 210 is an example of a storage unit that stores voltage values preset for each sheet type via the user operation unit 102 (input unit). The CPU 201 then causes the high-voltage power supply 55 to output a static elimination voltage based on the setting value acquired in Sb2, causing the static elimination roller 51b to neutralize the sheet S (Sb3). In other words, in the media setting mode, which is an example of the second mode, the CPU 201 determines the voltage value to be output by the high-voltage power supply 55 (voltage application unit) based on the type of sheet to be used in the job, by referring to information stored in the storage unit.

[0071] In Sb4, the CPU 201 determines whether the current sheet S is the final sheet in the image forming job, and if it is not the final sheet (Sb4N), the CPU 201 returns to Sb3 and repeats the same process for the subsequent sheets S. If the current sheet S is the final sheet (Sb4Y), the CPU 201 ends the process.

[0072] (Automatic correction mode) In the automatic correction mode, the CPU 201 changes the neutralization voltage based on the detection result of the current detection circuit 55a when the sheet S passes through the neutralization nip. In other words, in the automatic correction mode (first mode), the CPU 201 changes the value of the voltage output from the high-voltage power supply 55 (voltage application means) based on the detection result of the current detection circuit 55a (current detection means) when the sheet S passes through the neutralization roller 51b. Specific control aspects of the automatic correction mode in this embodiment will be described below.

[0073] First, the CPU 201 acquires job information (Sc1). The image forming apparatus 100 starts an image forming operation based on the job information. Meanwhile, the CPU 201 acquires a set value of the static elimination voltage in preparation for the static elimination process in the static elimination device 300 (Sc2). The set value of the static elimination voltage acquired in Sc2 is, for example, a value input in advance by the user via the static elimination operation unit 54 (voltage adjustment switch 54b). The CPU 201 determines the set value of the static elimination voltage acquired in Sc2 as the value of the static elimination voltage (initial static elimination voltage) to be output by the high-voltage power supply 55 in the period immediately after the start of the image formation job (Sc3).

[0074] Hereinafter, the current value detected by the current detection circuit 55a from the time when the leading edge of the sheet S in the sheet conveyance direction Cv enters the discharge nip until the trailing edge of the sheet S exits the discharge nip is referred to as the discharge current for the sheet S during paper passage. For the first few sheets S in an image formation job, applying an initial discharge voltage (a predetermined voltage value) to the discharge roller 51b is considered to be a value that allows the discharge current during paper passage to properly discharge the sheets S. However, for example, during an image formation job that outputs a large number of sheets S, the discharge roller 51b may not be able to properly discharge the sheets S due to resistance fluctuations or the like caused by the reasons described above. In this embodiment, discharge is also performed by the ionizer unit 52 disposed downstream of the discharge roller 51b, but the amount of charge that the ionizer unit 52 can discharge is smaller than that of the discharge roller 51b. Therefore, if the discharge roller 51b cannot properly discharge the sheets S, the sheets S may not be properly discharged before they are discharged from the discharger 300.

[0075] Therefore, in this embodiment, the measured value of the discharge current for the first predetermined number N of sheets S in the image forming job is stored as the initial discharge current, and control is performed to correct the value of the subsequent discharge voltage based on the initial discharge current.

[0076] The number of sheets S (predetermined number N) for measuring the initial static elimination current is preferably two or more to reduce the influence of variations among the sheets S. In this embodiment, the predetermined number N is set to 3, but it may be set to another value.

[0077] The CPU 201 counts the number of sheets S currently conveyed to the static eliminator 300, counting the first sheet S conveyed to the static eliminator 300 since the start of the image forming job as the first sheet, and acquires the static elimination current for each sheet S while it is being conveyed (Sc4). If the current sheet S is a predetermined number of sheets since the start of the job (Sc5Y), the CPU 201 calculates an initial static elimination current I0 based on the values of the static elimination currents of the first to predetermined number of sheets S (Sc6). In this embodiment, the average value of the values of the static elimination currents of the first to predetermined number of sheets S is set as the initial static elimination current I0.

[0078] The initial discharge current I0 is a target value (target current value) of the discharge current (controlled variable, controlled amount) during execution of an image forming job. That is, in this embodiment, the target value of the discharge current is determined based on the detection result of the current detection circuit 55a when the sheet S passes through the discharge roller 51b (discharge member) after the start of the job while the high-voltage power supply 55 is applying a voltage of a predetermined voltage value to the discharge roller 51b.

[0079] Furthermore, following the calculation of the initial static elimination current I0, the CPU 201 calculates a threshold value Ith for determining whether or not to correct the static elimination voltage (Sc7). The threshold value Ith is an amount (unit: μA) that determines how much the static elimination current during paper passage must deviate from the initial static elimination current I0 before the static elimination voltage is corrected.

[0080] In this embodiment, the value of the threshold value Ith is determined by the following method. The set value of the static elimination voltage set via the static elimination operation unit 54 is set to V0 (kV). The initial static elimination current is set to I0. The fluctuation range of the static elimination voltage when the ones digit is changed by 1 using the voltage adjustment switch 54b is set to ΔV (kV). In this case, the threshold value Ith is calculated by the following formula. Ith = | I0 / V0 ×ΔV |

[0081] In other words, the threshold value Ith in this embodiment is defined as the absolute value of the product of the initial static elimination current I0 divided by the set value V0 of the static elimination voltage and the resulting product by the fluctuation width ΔV of the static elimination voltage corresponding to the minimum adjustment unit of the voltage adjustment switch 54 b. For example, when the initial static elimination current I0 is −40 μA, the set value V0 of the initial voltage is −4.0 kV, and the fluctuation width ΔV of the static elimination voltage is −0.1 kV, the threshold value Ith is 1.0 μA.

[0082] If the current sheet S is a sheet that is more than a predetermined number of sheets after the start of the job, the CPU 201 acquires the neutralization current I of the current sheet S during sheet passage (Sc8). Then, the CPU 201 compares the absolute value of the difference between the neutralization current I during sheet passage and the initial neutralization current I0 with the aforementioned threshold value Ith (Sc9). If the absolute value of the difference between I and I0 is greater than the threshold value Ith (Sc9Y), the CPU 201 determines that the value of the neutralization voltage needs to be corrected, and corrects the value of the neutralization voltage so that the neutralization current approaches the target value (I0) (Sc10). If the absolute value of the difference between I and I0 is equal to or less than the threshold value Ith (Sc9N), the CPU 201 determines that the value of the neutralization voltage does not need to be corrected, and maintains the value of the neutralization voltage.

[0083] For example, consider a case where the initial neutralization current I0 is -40 μA, the initial voltage setting value V0 is -4.0 kV, the neutralization voltage fluctuation width ΔV is -0.1 kV, and the threshold value Ith is 1.0 μA. In this case, if the neutralization current I during the passage of the current sheet S is smaller than -41 μA or larger than -39 μA, the neutralization voltage is corrected (Sc10). If the neutralization current I for the fourth sheet S is -42 μA, the absolute value of the difference from the initial neutralization current I0 is 2 (μA), which is larger than the threshold value Ith, and therefore the neutralization voltage is corrected so that the absolute value of the neutralization current I becomes smaller. The correction width of the neutralization voltage is set to, for example, the neutralization voltage fluctuation width ΔV corresponding to the minimum adjustment unit of the voltage adjustment switch 54b. That is, the value of the neutralization voltage applied to the neutralization roller 51b by the high-voltage power supply 55 is corrected by 0.1 kV from the initial voltage setting value V0 of −4.0 kV to −3.9 kV, which is a lower voltage.

[0084] In this embodiment, the correction width of the static elimination voltage is set to a fixed value (0.1 kV) regardless of the magnitude of the absolute value of the difference between the detected static elimination current I and the initial static elimination current I0, but the correction width may be changed depending on the absolute value of the difference between I and I0.

[0085] Thereafter, the CPU 201 determines whether the current sheet S is the final sheet in the image forming job, and if it is not the final sheet (Sc11N), returns to Sc8 and repeats the same process for the subsequent sheet S. If the current sheet S is the final sheet (Sc11Y), the CPU 201 ends the process.

[0086] (Example of changes in static elimination voltage and static elimination current) An example of the transition of the static elimination voltage and static elimination current when the above control is performed is shown in Figure 7. For several sheets S immediately after the start of an image formation job, an initial static elimination voltage is applied at the static elimination voltage setting value V0, and the static elimination current during sheet passage is the initial static elimination current I0. However, as time passes, the value of the static elimination current deviates from the initial static elimination current I0.

[0087] In the example of FIG. 7, for the mth sheet S from the start of the job, the absolute value of the static elimination current I_m during sheet passage becomes greater than the absolute value of the initial static elimination current I0, and the difference becomes greater than the threshold value Ith. In this case, after the mth sheet S leaves the static elimination nip and before the (m+1)th sheet S enters the static elimination nip, the static elimination voltage is corrected (Sc10 in FIG. 6). The static elimination voltage is corrected to a voltage value lower than the initial static elimination voltage (V0) so that the static elimination current approaches the initial static elimination current I0, that is, in this case, so that the absolute value of the static elimination current becomes smaller. As a result, the static elimination current I_m+1 of the (m+1)th sheet S becomes a value close to the initial static elimination current I0.

[0088] In this embodiment, the neutralization voltage is corrected based on a comparison between the detection result of the neutralization current during paper passage and the target value of the neutralization current during paper passage. This is because the neutralization current during paper passage can be used to uniquely determine the current value required to properly neutralize the charged sheet S. The magnitude of the current flowing through the neutralization nip when the sheet S is not passing through the neutralization nip (when paper is not passing through) does not take into account the electromotive force generated by the charge on the sheet S. Therefore, it may be difficult to properly correct the neutralization voltage, especially when using a high-resistance sheet S such as plastic film or synthetic paper. In response to this, feedback control based on the detection result of the neutralization current during paper passage can correct the neutralization voltage according to the resistance value of the neutralization roller 51b and the amount of charge on the sheet S.

[0089] In this way, in the automatic correction mode, feedback control is performed to change the set value of the static elimination voltage for the subsequent sheet that passes through the static elimination nip after the preceding sheet during the job, based on the detection result of the static elimination current when the preceding sheet during the job passes through the static elimination nip. This makes it possible to maintain the static elimination voltage at an appropriate value during continuous print jobs, making it more difficult for sheets to stick together.

[0090] Furthermore, the automatic correction mode can reduce the workload on the user compared to when the user manually adjusts the static elimination voltage.

[0091] <Manual setting of static elimination voltage> An example of a method for manually setting the set value of the static elimination voltage in the manual setting mode will be described below. In the manual setting mode, the user operates the user operation unit 102 or the static elimination operation unit 54 to input the set value of the static elimination voltage to the static elimination device 300, and the control circuit 200 causes the high-voltage power supply 55 to output the static elimination voltage based on the input set value.

[0092] Manually adjusting the static elimination voltage has the following advantages. First, it allows for fine adjustments to suit various media. The manual setting mode can be used appropriately when it is expected that the static elimination voltage value set in the automatic correction mode will deviate from the appropriate value, such as for a sheet S made up of multiple materials with different properties, such as label paper or laminated paper, or a sheet S with different physical properties on the front and back sides. Furthermore, it is expected that the static elimination voltage value set in the automatic correction mode will deviate from the appropriate value depending on the content of the image formed on the sheet S (for example, when an extreme image such as a solid image is repeatedly formed on the entire surface), but the manual setting mode can be used appropriately even in such cases.

[0093] Second, it can accommodate the fact that the target values for the output results (use of the finished product) vary from user to user. The general advantage of neutralizing the sheets S is that it prevents the sheets S from sticking together and makes it easier to handle the sheets S in the subsequent post-processing process. On the other hand, neutralizing the sheets S also has the advantage of making it easier to turn the pages and reducing the noise when the sheets S are peeled off in the final finished product, for example, after they have been bound. The way in which static electricity should be neutralized from the sheets S may differ depending on the use of the finished sheets S. In such cases, the manual setting mode allows the user to adjust the neutralization voltage to suit the application.

[0094] 8 is a flowchart showing a method for setting the static elimination voltage in the manual setting mode. Note that this flowchart is merely an example, and in practice, the method determined by each user may be used, and the criteria and timing for determining the values are not limited to those shown in the figure.

[0095] First, in S201, a sample output is performed. This may be performed by instructing the image forming system 400 to execute a mode (adjustment mode) in which a sheet S for adjustment is output as a sample, or by extracting a portion of the sheet S discharged as a product during execution of a normal job as a sample. Also, a measurement unit that measures the surface potential of the sheet S may be provided on the transport path of the sheet S in the image forming system 400.

[0096] In S202, the surface potential of the sample sheet S is measured. To measure the surface potential, for example, a measuring device (surface potential meter) shown in Fig. 9 is used. In this case, the sheet S is placed on a reference earth plate 71, and the surface potential of the opposing portion 72 is measured, thereby measuring the potential difference between the front and back of the sheet S.

[0097] Here, Vs is the threshold value of the potential difference between the front and back surfaces that satisfies the quality of the deliverable. If the measurement result of S202 shows that the potential of the first surface Sa relative to the second surface Sb (FIG. 2) is equal to or higher than +Vs, it is determined that the static elimination voltage is excessive (S203Y), and the static elimination voltage setting is lowered (S204). That is, the user operates the user operation unit 102 or the static elimination operation unit 54 to input a value whose absolute value is smaller than the current setting value as the static elimination voltage setting. Then, a sample is output again (S205), and the process returns to S202 to perform measurement.

[0098] Conversely, if the measurement result in S202 shows that the potential of the first surface Sa relative to the second surface Sb (FIG. 2) is -Vs or less, it is determined that the static elimination voltage is insufficient (S206Y), and the static elimination voltage setting is increased (S207). That is, the user operates the user operation unit 102 or the static elimination operation unit 54 to input a value with an absolute value greater than the current setting as the static elimination voltage setting. Then, sample output is performed again (S208), and the process returns to S202 to perform measurement.

[0099] The above adjustment is repeated until the potential difference between the front and back sides falls within the range of ±Vs in the measurement result of S202, and when the potential difference between the front and back sides falls within the range (S203N, S206N), the adjustment is terminated (S209).

[0100] <Selecting the static elimination voltage setting mode> 10(a) to 10(d) will be used to explain a configuration that allows the user to select the setting mode of the static elimination voltage. Figures 10(a) to 10(d) are examples of screens displayed on the display unit 102a (FIG. 1) of the user operation unit 102.

[0101] The screen of FIG. 10(a) is displayed, for example, when the home screen is displayed on the display unit 102a, by opening a setting screen (user mode) for setting the functions of the image forming system 400 and then selecting an item related to adjusting the static elimination voltage. In this embodiment, the user can select the static elimination voltage setting method from among automatic correction mode, manual setting mode, and media setting mode by pressing any of buttons B1 to B3 displayed on the screen of FIG. 10(a). Pressing the "adjustment switch" button B1 selects the manual setting mode. Pressing the "media setting" button B2 selects the media setting mode. Pressing the "automatic correction" button B3 selects the automatic correction mode.

[0102] In this way, the display unit 102a that displays a screen for allowing the user to select a method for setting the static elimination voltage is an example of a selection means for selecting the mode to be executed by the control circuit 200 (control means) from among a plurality of modes.

[0103] When the manual setting mode is selected (FIG. 10(b)), the static elimination voltage setting value is, for example, the static elimination voltage value adjusted according to the above-mentioned flowchart (FIG. 8) (Sa1 to Sa3 in FIG. 6). In the flowchart of FIG. 8, the static elimination voltage is adjusted based on the potential difference between the front and back of the sheet S measured by a surface electrometer, but for example, the user may touch the sheets S to check the degree of adhesion to each other and adjust the static elimination voltage value in stages so as to reduce the adhesion force.

[0104] One advantage of the manual setting mode is that it is easy for the user to grasp the set value of the static elimination voltage. If the environment in which the image forming system 400 is installed and the environmental conditions for job execution are stable and the job content is standardized, fixing the set value of the static elimination voltage can reduce the possibility of problems occurring due to the static elimination voltage unintentionally deviating from the appropriate value.

[0105] In the manual setting mode, the set value of the static elimination voltage may be changed dynamically (i.e., during execution of a job). For example, during execution of a continuous print job, a sample sheet S may be extracted and measured with a surface electrometer, and the set value of the static elimination voltage may be changed or output / stop of output of the static elimination voltage may be switched based on the measurement results. Also, the set value of the static elimination voltage may be changed in accordance with the timing when the operation mode of the image forming system 400 is switched during the job.

[0106] When the media setting mode is selected (FIG. 10(c)), the setting screen for configuring settings for each sheet type allows the user to input the static elimination voltage setting value as well as the basis weight and surface properties of the sheet S, and the input value is reflected when the job is executed (Sb1 to Sb4 in FIG. 6). In this case, for example, by determining and setting an appropriate static elimination voltage value for each sheet type in advance according to the flowchart in FIG. 9, it is possible to perform appropriate static elimination even when the same type of sheet S is used over multiple days.

[0107] When the automatic correction mode is selected (FIG. 10(d)), as described above, the set value of the neutralization voltage is automatically determined by feedback control based on the detection results of the neutralization current while the paper is passing (Sc1 to Sc11 in FIG. 6). This mode has the advantage of reducing the burden on the user when adjusting the neutralization voltage. In addition, the neutralization voltage can be automatically corrected in response to changes in environmental conditions, etc., without outputting a sample sheet S in addition to the final sheet S. For this reason, the automatic correction mode may be suitable, for example, when running continuous print jobs over a long period of time using the same type of synthetic paper (high-resistance sheet).

[0108] (Variation) In this embodiment, a configuration in which three modes, namely, an automatic correction mode, a manual setting mode, and a media setting mode, can be selected as a method for setting the static elimination voltage is exemplified. However, the static elimination device 300 and the image forming system 400 may be configured to select only two of the above three modes as a method for setting the static elimination voltage. For example, the static elimination device 300 and the image forming system 400 may be configured to select either the automatic correction mode or the manual setting mode as a method for setting the static elimination voltage. Furthermore, the static elimination device 300 and the image forming system 400 may be configured to select one of one or more of the above three modes and a mode other than the above three modes as a method for setting the static elimination voltage.

[0109] In this embodiment, the function of the static elimination device 300 automatically correcting the static elimination voltage during a job (the static elimination voltage automatic correction function) is enabled only when the “Automatic Correction” button B3 is selected on the screen of FIG. 10(a). The automatic static elimination voltage correction function is disabled when any of the other buttons B1 and B2 is selected on the screen of FIG. 10(a). That is, the automatic static elimination voltage correction function is enabled / disabled in response to an operation to select a mode for setting the static elimination voltage. Alternatively, for example, the display unit 102a of the user operation unit 102 may display a screen including a form (such as a check box or button) that allows the automatic static elimination voltage correction function to be enabled / disabled. In this case, for example, when a check box is checked, the automatic correction mode is set, and when the check box is unchecked, the manual setting mode or the media setting mode is set, depending on the user's selection. Furthermore, when a check box is checked (the automatic correction function is enabled), the first mode is selected, and when the check box is unchecked (the automatic correction function is disabled), the second mode is selected.

[0110] The user operation unit 102, which is configured to allow the mode of the static elimination voltage setting method to be selected via a screen display, is an example of a selection means, and the selection means is not limited to this. For example, the mode of the static elimination voltage setting method may be changed by operating an external computer that is communicatively connected to the image forming system 400. In this case, the control circuit 200, which is configured to receive instructions regarding mode selection from the external computer, functions as the selection means.

[0111] In the automatic correction mode, the set value of the static elimination voltage (Sc2 in FIG. 6) acquired at the start of a job may be automatically acquired based on the detection results of the current or voltage when a test sheet S, separate from the final sheet S, is passed through the static elimination nip. For example, after a test image is formed on the test sheet S using an operation similar to a normal image formation operation, the voltage applied to the static elimination roller 51b is controlled at a constant current, and the change in the voltage applied to the static elimination roller 51b is measured when the test sheet S passes through the static elimination nip. Because the charge on the surface of the sheet S acts as an electromotive force in the static elimination nip, the amount of charge on the sheet S can be observed as a change in the applied voltage. The set value of the static elimination voltage is then determined based on the relationship between the amount of charge and the change in the applied voltage, which are previously calculated and stored in ROM 220, and the relationship between the amount of charge and the appropriate value of the static elimination voltage.

[0112] Example 2 Hereinafter, a description will be given of Example 2. The static eliminator 300 of this example has a function of automatically correcting the static elimination voltage in a control mode different from the automatic correction mode of Example 1. Hereinafter, elements with the same reference symbols as those of Example 1 will be considered to have basically the same configurations and functions as those described in Example 1 unless otherwise specified, and differences from Example 1 will be mainly described.

[0113] As will be described below, in this embodiment, three modes can be selected as modes for automatically correcting the neutralization voltage: a current detection mode, a paper feed count mode, and an environmental condition mode. The current detection mode, the paper feed count mode, and the environmental condition mode are all examples of a first mode that automatically changes the value of the voltage output from the high-voltage power supply 55 (voltage application means) during job execution.

[0114] As described above, in this embodiment, three control modes are prepared as the first mode: the current detection mode, the number of sheets passed mode, and the environmental condition mode. However, the present invention is not limited to these, and the control circuit 200 may be configured to be able to execute one of a plurality of control modes including at least one of the current detection mode, the number of sheets passed mode, and the environmental condition mode.

[0115] The static eliminator 300 of this embodiment can execute a current detection mode, a paper feed count mode, and an environmental condition mode in addition to the manual setting mode and media setting mode of Embodiment 1. However, the static eliminator 300 may be configured to execute only the current detection mode, the paper feed count mode, and the environmental condition mode (or even only some of them).

[0116] <Adjusting the static elimination voltage according to the number of sheets passed> In this embodiment, the resistance value of the discharge roller 51b varies depending on the number of sheets S passed (number of sheets passed continuously) from the start of the job. This is mainly because the temperature of the discharge roller 51b, which was at room temperature before the job started, gradually rises during the job as the sheet S heated by the fixing device 40 comes into contact with the discharge roller 51b. When the temperature of the discharge roller 51b rises, the resistance value of the discharge roller 51b decreases, and the current that flows when the same discharge voltage is applied tends to increase.

[0117] For this reason, the control circuit 200 (FIG. 5) of this embodiment can select a mode (passed sheet number mode) in which the set value of the static elimination voltage is gradually reduced according to the number of sheets continuously passed during a job. That is, in the passed sheet number mode, which is an example of the first mode, the control circuit 200 (control means) changes the value of the voltage output from the high-voltage power supply 55 (voltage application means) based on the number of sheets conveyed during execution of the job.

[0118] FIG. 12 is a graph showing an example of the relationship between the number of continuously fed sheets and the setting ratio of the static elimination voltage. The setting ratio of the static elimination voltage is expressed by taking the value of the static elimination voltage suitable for eliminating static electricity from the sheet S (optimal value of the static elimination voltage) as the standard value of the optimal static elimination voltage at the start of the job (100%). Data corresponding to FIG. 12 (table or conversion formula parameters) is assumed to be stored in advance in the ROM 220 of the control circuit 200. Furthermore, since this relationship may differ depending on the type of sheet S, it is preferable to prepare multiple sets of data for each sheet type (or for each classification into which sheet types are classified). However, regardless of the physical properties of the sheet S, the setting ratio of the static elimination voltage usually gradually decreases with the number of continuously fed sheets.

[0119] For example, if the relationship between the number of continuously passed sheets and the setting ratio of the static elimination voltage is as shown in Fig. 12, when the number of continuously passed sheets reaches 100, the setting value of the static elimination voltage is changed to 80% of the initial static elimination voltage. For example, if the static elimination voltage is set to 4.0 kV in the static elimination operation unit 54 and a continuous print job is started in the paper passing history mode (button B5 in Fig. 13, which will be described later) selected, a static elimination voltage of 3.2 kV is applied to sheets S from the 100th sheet onwards.

[0120] When the period during which the image forming system 400 is not performing a job (the period during which the sheet S is not conveyed to the static elimination device 300, the standby period) becomes longer, the temperature of the static elimination roller 51b gradually approaches room temperature. Therefore, after the previous job is completed, the value of the static elimination voltage at the start of the next job is set to a value close to a set ratio of 100% according to the length of the standby period. In other words, when the next job is started immediately after the previous job is completed, the value of the static elimination voltage at the start of the next job is applied based on a set ratio according to the number of continuously fed sheets of the previous job. On the other hand, when the next job is started after a sufficient amount of time has passed since the previous job was completed, the value of the static elimination voltage at the start of the next job is applied, for example, to the value of the initial static elimination voltage (a value with a set ratio of 100%) set by the static elimination operation unit 54, regardless of the number of continuously fed sheets of the previous job.

[0121] <Adjusting the static elimination voltage according to environmental conditions> Furthermore, even if the type of sheet S is the same, the resistance value of the sheet S may change depending on the environmental conditions (particularly the amount of moisture in the environment) in which the static eliminator 300 is installed, and this may cause the optimum value of the static elimination voltage to fluctuate.

[0122] In this embodiment, when the automatic correction function is enabled, it is possible to select an environmental condition mode (button B4 in FIG. 13) that automatically determines the set value of the static elimination voltage based on the environmental conditions. That is, in the paper feed number mode, which is an example of the first mode, the control circuit 200 (control means) changes the value of the voltage that is output from the high-voltage power supply 55 (voltage application means) based on the detection result of the environmental sensor 13 (environment detection means).

[0123] In the environmental condition mode of this embodiment, a preset value based on the amount of moisture in the environment is simply applied as the setting value for the neutralization voltage, and control is not performed based on the paper passing history or the detection results of the neutralization current during the job.

[0124] 11 is a graph showing the relationship between the environmental moisture content (weight absolute humidity, unit: g / kg) and the set value of the static elimination voltage. Data (table or conversion formula parameters) corresponding to FIG. 11 are assumed to be stored in advance in the ROM 220 of the control circuit 200. When executing a job in the environmental condition mode, the control circuit 200 determines the set value of the static elimination voltage by referring to the data in the ROM 220 based on the environmental information detected by the environmental sensor 13. If the environmental information changes during the job, the set value of the static elimination voltage is changed as needed based on the detected environmental information.

[0125] In this way, by automatically correcting the set value of the static elimination voltage based on the detection result of the environment sensor 13, static elimination of the sheet S can be performed with a static elimination voltage appropriate for the environmental conditions.

[0126] <Selecting the static elimination voltage setting method> In this embodiment, the user can select the method of setting the static elimination voltage from the three modes described above. Fig. 13 shows an example of a selection screen for selecting the method of setting the static elimination voltage. The user can select one of three modes, namely, the environmental condition mode, the number of sheets passed mode, and the current detection mode, by operating the screen shown in Fig. 13 displayed on the display unit 102a (Fig. 1) of the user operation unit 102.

[0127] The selection screen in Fig. 13 is displayed when, for example, the "Automatic Correction" button B3 is selected on the setting screen (Fig. 10(a)) for the static elimination voltage setting method described in Example 1. If the static eliminator 300 does not have the functions of the manual setting mode and the media setting mode, the screen in Fig. 13 may be displayed instead of the setting screen in Fig. 10(a).

[0128] When the "Environmental Temperature and Humidity" button B4 is pressed, the aforementioned environmental condition mode is selected, in which a static elimination voltage value according to the environmental conditions is applied. For example, even if the image forming system 400 starts a continuous print job early in the morning (when the device is cold) and the temperature and humidity gradually increase during the job, a static elimination voltage according to the environmental moisture content is applied as needed. This reduces the possibility that the static elimination voltage will become excessive or insufficient due to changes in the environmental conditions during the job.

[0129] When the "Paper Pass History" button B5 is pressed, the aforementioned paper pass number mode is selected, which corrects the neutralization voltage according to the number of sheets passed continuously during the job. For example, when a large number of sheets S are passed intermittently in batches of several dozen sheets, the change in the appropriate value of the neutralization voltage while the several dozen sheets S that make up one batch are passed continuously can be considered to follow a certain pattern (such as the pattern in Figure 12). In such cases, the paper pass number mode may be appropriate. On the other hand, in the current detection mode described below, errors may occur in the first few sheets S before neutralization voltage correction begins or in the latter half of the continuous paper pass.

[0130] When the "Current Detection" button B6 is pressed, a current detection mode is selected, which automatically corrects the neutralization voltage based on the detection results of the neutralization current during the job. The control content in the current detection mode is the same as the automatic correction mode in the first embodiment (Sc1 to Sc11 in FIG. 6). For example, in continuous print jobs using the same type of synthetic paper, the current detection mode may be able to more appropriately respond to changes in the resistance of the neutralization roller 51b during the job or changes in the resistance of the synthetic paper due to environmental conditions.

[0131] In this embodiment, the user can select the mode for automatic correction of the static elimination voltage. This allows the user to select the mode that they deem most appropriate for the specific usage situation, improving usability and reducing sheet sticking by performing static elimination with a more appropriate static elimination voltage. This also reduces the amount of manual handling work required to eliminate sheet sticking and improves handling in post-processing processes, making it easier to handle a variety of sheet materials, including synthetic paper, film paper, and label paper.

[0132] Example 3 In the first and second embodiments, whether to enable the automatic correction function of the static elimination voltage and which of a plurality of modes to select when performing the automatic correction (hereinafter collectively referred to as static elimination voltage mode selection) are determined by user selection. The static elimination voltage mode selection may be performed automatically (i.e., independently of user selection) based on the type of sheet S or other conditions.

[0133] In this embodiment, information (media information) regarding the physical properties of the sheet S is input in advance for each type of sheet S via the user operation unit 102 and stored in a storage unit such as the ROM 220 or the RAM 210. The media information includes at least information indicating the volume resistivity of the sheet S or information related to the volume resistivity of the sheet S (such as material and thickness).

[0134] The method of inputting media information via the user operation unit 102 is not limited to this, but a media sensor capable of automatically determining the physical properties of the sheet S may be disposed in the static elimination device 300 or the image forming system 400, and the media information may be acquired based on the detection results of the media sensor. The media sensor may be, for example, an ultrasonic type that uses ultrasonic waves to determine the thickness (basis weight) of the sheet S, an optical type that irradiates light and determines the surface properties of the sheet S from the amount of reflected light, or a combination of an ultrasonic type and an optical type.

[0135] The control circuit 200 acquires media information corresponding to the type of sheet S to be used in the current job. Condition data indicating whether or not to enable the automatic correction function for the static elimination voltage and which of multiple modes to select when performing automatic correction for the media information is stored in advance in, for example, the ROM 220. The control circuit 200 references the condition data, selects the static elimination voltage mode, and applies one of the static elimination voltage setting methods described in the first and second embodiments.

[0136] The selection of the mode of the static elimination voltage according to the type of sheet S is based on, for example, the thickness of the high resistance layer of the sheet S. For a sheet S having a high resistance layer of 100 μm or more, the automatic correction mode of Example 1 is selected. For a sheet S having a high resistance layer of less than 100 μm or a sheet S having no high resistance layer, the media setting mode or manual setting mode is selected. The high resistance layer referred to here is a layer having a volume resistivity of 1×10 12 This is a layer made of a material with a resistivity of Ω·cm or higher, such as a surface treatment layer (coating layer) of PI (polyimide). For example, in the case of a sheet S with a 120 μm pulp layer coated with a 30 μm PI layer, the high resistance layer is less than 100 μm, so the media setting mode or manual setting mode is selected and a preset fixed value of static elimination voltage is applied. In this way, the control circuit 200 of this embodiment functions as a selection means for selecting one of multiple modes based on the type of sheet used for the job.

[0137] (Variation) In the third embodiment, an example was shown in which the mode of the static elimination voltage was automatically selected based on the type of sheet S (particularly the thickness of the high resistance layer), but the mode of the static elimination voltage may also be automatically selected based on other conditions.

[0138] As an example, the mode of the static elimination voltage may be automatically selected based on the environmental conditions (environmental moisture content) detected by the environmental sensor 13 (FIG. 5). For example, in a low-humidity environment, a relatively high static elimination voltage is required, and even a slight change in the moisture content can easily cause the appropriate value of the static elimination voltage to fluctuate, so the automatic correction mode may be selected. Conversely, in a high-humidity environment, the media setting mode or manual setting mode may be selected. In this case, the control circuit 200 functions as a selection means for selecting one of a plurality of modes based on the detection results of the environmental sensor 13 (environment detection means).

[0139] As another example, the mode of the static elimination voltage may be automatically selected based on the measurement value of the current flowing through the static elimination roller 51b or the secondary transfer roller 9. For example, if the measurement value of the current of the static elimination roller 51b is below a certain value, the application of the automatic correction mode may be stopped because there is a possibility that errors in the automatic correction mode will become large. In this case, the control circuit 200 functions as a selection means that selects one of a plurality of modes based on the detection result of the current detection circuit 55a (current detection means) that detects the current flowing through the static elimination roller 51b (static elimination member).

[0140] As yet another example, when the automatic correction function for the neutralization voltage is disabled (second mode), a notification may be issued if the difference between the current setting value of the neutralization voltage and the appropriate value of the neutralization voltage calculated based on the detection results of the neutralization current during paper passage, etc., exceeds a predetermined tolerance range. The notification refers to providing the user with information urging them to reset the neutralization voltage via the neutralization operation unit 54 or the user operation unit 102 in order to properly neutralize the sheet S. The notification may be issued using a screen display or audio on the user operation unit 102, or may be issued using a screen display or audio on an external computer connected to the image forming system 400. This modification has the advantage that, for example, in the case of a user who accurately understands the state of the deliverable, the charged state of the deliverable can be eliminated while reducing the burden on the user.

[0141] Other Examples In the above-described embodiments, the static eliminator 300 that eliminates static electricity from the sheet S has been described. However, the static eliminator 300 also functions as a charge adjustment device that adjusts the charge state of the sheet S by supplying charge to the sheet S via the static eliminator roller 51b as a charge supply member. The charge adjustment device may not necessarily reduce (eliminate) the amount of charge on the sheet S. For example, the charge adjustment device may adjust the amount of charge on each surface of the sheets S so that the opposing surfaces of overlapping sheets S are charged to the same polarity when the sheets S are stacked after processing by the charge adjustment device. Specifically, the charge adjustment device applies a voltage to every other sheet so that the electrostatic polarity of the sheet surface is reversed. In this case, since the opposing surfaces of overlapping sheets are charged to the same polarity, sticking of the sheets due to electrostatic force can be reduced. Furthermore, by applying the control described in each embodiment to the voltage applied to the static eliminator roller 51b as a charge supply member, the charge state of the sheets S can be more appropriately adjusted.

[0142] In addition, in the above-described embodiments, the static elimination roller 51b, which is a roller member, has been described as an example of a contact-type static elimination member that comes into contact with the sheet S. However, the contact-type static elimination member is not limited to this, and may be, for example, a brush member in which conductive fibers or elongated conductive sheet pieces come into contact with the sheet S.

[0143] Furthermore, in the above-described embodiments, the sheet S is mainly charged at a transfer unit in an electrophotographic process. However, this is not limiting, and even in an image forming system other than an electrophotographic system, such as an inkjet system, the sheet S may be charged by frictional charging or peeling charging due to rubbing or peeling against a conveyance guide, a conveyance roller, a conveyance belt, or the like. Therefore, the present technology may be applied to an image forming system other than an electrophotographic system.

[0144] (Other embodiments) The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program.The present invention can also be realized by a circuit (e.g., ASIC) that realizes one or more functions. [Explanation of symbols]

[0145] 51b... static elimination member (static elimination roller) / 54, 102... input means (static elimination operation unit, user operation unit) / 55... voltage application means (high voltage power supply) / 102... selection means (user operation unit) / 200... control means (control circuit)

Claims

1. a static elimination member that comes into contact with the sheet and eliminates static electricity from the sheet; a voltage applying means for applying a voltage to the charge removing member; an input means for inputting a value of a voltage that the voltage application means applies to the static eliminator; a control means for controlling the voltage application means, the control means being capable of executing a plurality of modes including a first mode in which a value of a voltage output by the voltage application means is automatically changed during execution of a job in which the sheet is neutralized by the neutralizing member while being conveyed, and a second mode in which a voltage is output based on a value input via the input means without automatically changing the value of a voltage output by the voltage application means during execution of the job; a selection means for selecting a mode to be executed by the control means from among the plurality of modes; A static eliminator comprising:

2. the selection means includes a display unit that displays a screen for allowing a user to select one of the plurality of modes.

2. The static eliminator according to claim 1.

3. the selection means selects one of the plurality of modes based on the type of sheet used in the job.

2. The static eliminator according to claim 1.

4. The static eliminator further includes an environment detection means for detecting an environmental condition of an environment in which the static eliminator is installed, The selection means selects one of the plurality of modes based on the detection result of the environment detection means.

2. The static eliminator according to claim 1.

5. The device further includes a detection unit that detects a voltage applied to the neutralization member or a current flowing through the neutralization member, The selection means selects one of the plurality of modes based on the detection result of the detection means.

2. The static eliminator according to claim 1.

6. Further, a current detection means for detecting a current flowing through the static eliminator is provided, In the first mode, the control means changes the value of the voltage that the voltage application means outputs based on the detection result of the current detection means when the sheet passes through the static elimination member. The static eliminator according to any one of claims 1 to 5.

7. The static eliminator further includes an environment detection means for detecting an environmental condition of an environment in which the static eliminator is installed, In the first mode, the control unit changes the value of the voltage output by the voltage application unit based on the detection result of the environment detection unit during execution of the job. The static eliminator according to any one of claims 1 to 5.

8. the control unit changes the value of the voltage to be output by the voltage application unit based on the number of sheets conveyed during execution of the job in the first mode. The static eliminator according to any one of claims 1 to 5.

9. The control means is capable of executing a plurality of control modes, including at least one of the following, as the first mode: (1) a control mode in which the value of the voltage to be output by the voltage application means is changed based on the detection result of a current detection means that detects the current flowing through the static eliminator; (2) a control mode in which the value of the voltage to be output by the voltage application means is changed based on the detection result of an environment detection means that detects the environmental conditions of the environment in which the static eliminator is installed; and (3) a control mode in which the value of the voltage to be output by the voltage application means is changed based on the number of sheets that have passed through the static eliminator during execution of the job. The static eliminator according to any one of claims 1 to 5.

10. the control means, in the second mode, causes the voltage application means to output a voltage at a value input via the input means before the start of the job, regardless of the type of sheet used for the job. The static eliminator according to any one of claims 1 to 5.

11. In the second mode, when the input means is operated after the job is started, the control means changes the value of the voltage to be output by the voltage application means from the value input via the input means before the job is started to the value input via the input means after the job is started. The static eliminator according to claim 10 .

12. a storage unit that stores a voltage value preset via the input means for each type of sheet; the control unit, in the second mode, refers to information stored in the storage unit based on the type of sheet used for the job, and determines a value of the voltage to be output by the voltage application unit. The static eliminator according to any one of claims 1 to 5.

13. The control means is capable of executing a plurality of control modes, including at least one of the following as the second mode: (1) a control mode in which a value of a voltage to be output by the voltage application means during execution of the job is determined based on a value input via the input means before the start of the job, regardless of the type of sheet used for the job; and (2) a control mode in which a value of a voltage to be output by the voltage application means during execution of the job is determined based on the type of sheet used for the job. The static eliminator according to any one of claims 1 to 5.

14. In the second mode, when a difference between a value of the voltage output by the voltage application means during execution of the job and a value calculated by the control means during execution of the job as a voltage value suitable for application to the static eliminator exceeds a predetermined allowable range, the control means notifies a user of information urging the user to reset the voltage to be applied to the static eliminator. The static eliminator according to any one of claims 1 to 5.

15. an image forming device that forms an image on a sheet; The static eliminator according to claim 1 , which eliminates static electricity from a sheet on which an image has been formed by the image forming apparatus; An image forming system comprising:

16. a charge supply member that contacts the sheet and supplies an electric charge to the sheet; a voltage applying means for applying a voltage to the charge supply member; input means for inputting the value of the voltage applied by the voltage application means to the charge supply member; a control means for controlling the voltage application means, the control means being capable of executing a plurality of modes including a first mode in which a value of a voltage output by the voltage application means is automatically changed during execution of a job in which a charged state of a sheet is adjusted by the charge supply member while the sheet is being conveyed, and a second mode in which a voltage is output based on a value input via the input means without automatically changing the value of a voltage output by the voltage application means during execution of the job; a selection means for selecting a mode to be executed by the control means from among the plurality of modes; A charge adjustment device comprising:

Images