Static elimination device, image formation device and image formation system

Abstract

To obtain excellent handleability even for a high-resistance medium.SOLUTION: There is provided a static elimination device which eliminates electric charges from a recording medium where the electric charges are generated, and the static elimination device comprises: a first static elimination part, which applies a first static elimination bias having the opposite polarity from electric charges generated on one surface of the recording medium, on the one surface; and a second static elimination part, which applies a second static elimination bias having the opposite polarity from electric charges generated on the other surface of the recording medium, on the other surface.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a static eliminator, an image forming apparatus, and an image forming system. [Background technology]

[0002] Patent document 1 describes an image forming system having an image forming device and a charge removal device, in which the image forming device has a fixing section that heats and pressurizes a recording sheet onto which a toner image has been transferred, thereby fixing the toner image to the recording sheet, and the charge removal device has a charge control section that applies a voltage to the recording sheet onto which a toner image has been fixed on both sides, and collects charge on the second of the two sides of the recording sheet onto which the toner image has been fixed later, and a charge removal section that is provided downstream of the charge control section in the transport direction of the recording sheet, and removes the charge collected on the second side. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2018-084622 Summary of the Invention [Problem to be solved by the invention]

[0004] The configuration described in Patent Document 1 cannot sufficiently remove static electricity from a recording medium such as a resin film that has a higher volume resistance than paper (hereinafter also referred to as a high resistance medium).As a result, there are problems with poor handling of the high resistance medium, such as the charged high resistance medium sticking to the transport path, the high resistance medium discharged to the discharge tray not being aligned, and the high resistance medium sticking to itself on the discharge tray. [Means for solving the problem]

[0005] The present invention provides a discharge device that removes electric charge from a recording medium on which electric charge has been generated, and is characterized in that it comprises a first discharge unit that applies a first discharge bias of opposite polarity to the electric charge generated on one side of the recording medium, and a second discharge unit that applies a second discharge bias of opposite polarity to the electric charge generated on the other side of the recording medium, to the other side of the recording medium. Effect of the Invention

[0006] According to the present invention, good handling properties can be achieved even in the case of a high resistance medium. [Brief description of the drawings]

[0007] [Figure 1] FIG. [Diagram 2] FIG. 1 is a schematic diagram of an image forming apparatus. [Diagram 3] FIG. 11 is an explanatory diagram showing the charge potential distribution of a recording medium discharged without neutralization. [Figure 4] FIG. 6 is an explanatory diagram showing an example of a charge potential distribution on a recording medium discharged after static electricity is removed. [Diagram 5] FIG. 11 is an explanatory diagram showing another example of the charge potential distribution of the recording medium discharged after static elimination. [Figure 6] FIG. 1 is a schematic diagram illustrating an example of an image forming system. [Figure 7] FIG. 13 is a schematic configuration diagram showing another example of an image forming system. [Figure 8] 1 is a block diagram showing an example of a hardware configuration of an image forming apparatus according to an embodiment of the present invention; [Figure 9] FIG. 2 is a hardware block diagram of the static eliminator. [Figure 10] 4 is a flowchart of control executed by a CPU for the static eliminator. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of the invention will be described with reference to the drawings. In the description of the drawings, the same elements are given the same reference numerals, and duplicated explanations will be omitted.

[0009] <Configuration of the static eliminator> First, the configuration of the static eliminator according to the embodiment will be described with reference to Fig. 1. Fig. 1 is a schematic diagram of the static eliminator.

[0010] The static eliminator 6 includes a static eliminator 61 and a static eliminator 62. The static eliminator 61 includes, for example, a pair of static eliminator rollers 61a and 61b that transport the recording medium S. From the viewpoint of achieving both the transport performance of the recording medium S and the static eliminator performance, it is desirable that the static eliminator rollers 61a and 61b are conductive rollers having an elastic layer made of conductive rubber or conductive sponge formed on the surface of the core metal of the roller.

[0011] Of the static electricity removing rollers 61a and 61b, the core metal 61a1 of the static electricity removing roller 61a is connected to a high-voltage power supply 61c. The high-voltage power supply 61c applies a voltage V1 of opposite polarity to the charge (negative charge in this example) generated on one side of the recording medium S to the static electricity removing roller 61a. The static electricity removing roller 61a comes into contact with one side of the recording medium S, thereby applying the voltage V1 of opposite polarity to the charge generated on that surface to the one side of the recording medium S. Here, the voltage V1 is an example of a "first static electricity removing bias," and the static electricity removing unit 61 is an example of a "first static electricity removing unit."

[0012] The static elimination unit 62 is provided downstream of the static elimination unit 61 in the transport direction of the recording medium S, and has, for example, a pair of static elimination rollers 62a, 62b that transport the recording medium S. From the viewpoint of achieving both transport performance and static elimination performance for the recording medium S, the static elimination rollers 62a, 62b are also desirably conductive rollers having an elastic layer made of conductive rubber or conductive sponge formed on the surface of the roller core metal.

[0013] Of the static electricity removing rollers 62a and 62b, the core metal 62b1 of the static electricity removing roller 62b is connected to a high-voltage power supply 62c. The high-voltage power supply 62c applies a voltage V2 of the opposite polarity to the charge (positive charge in this example) generated on the other side of the recording medium S to the static electricity removing roller 62b. The static electricity removing roller 62b contacts the other side of the recording medium S, that is, the side opposite to the side in contact with the static electricity removing roller 61a, thereby applying a voltage V2 of the opposite polarity to the charge generated on that side to the other side of the recording medium S. Here, the voltage V2 is an example of a "second static electricity removing bias," and the static electricity removing unit 62 is an example of a "second static electricity removing unit."

[0014] The negative and positive charges on the recording medium S are generated by a process (for example, a toner image transfer) performed by a processing device (for example, an image forming device) provided upstream of the charge removing device 6 in the conveying direction of the recording medium S.

[0015] If the recording medium is plain paper, the volume resistance is low and charges flow easily through the paper. Therefore, the charge-eliminating bias also easily passes through the paper, and charge elimination on one side of the paper can be performed from either one side of the paper or the other side of the paper. In other words, charge can be eliminated from one side of the paper by applying a voltage of the opposite polarity to the charge generated on that side to that side, and charge can also be eliminated from one side of the paper by applying a voltage of the same polarity to the other side of the paper with the same polarity as the charge generated on the opposite side (one side of the paper).

[0016] On the other hand, when the recording medium is a recording medium (high resistance medium) with a higher volume resistance than paper, such as a resin film, it does not work like plain paper, and the latter method (applying a voltage of the same polarity from the opposite side of one side) may not be able to fully neutralize one side of the high resistance medium. For this reason, the former method (applying a voltage of the opposite polarity directly to one side) is easier to handle various recording media.

[0017] The recording medium S has one side (e.g., the front side) thereof neutralized by the neutralization section 61, and then the other side (e.g., the back side) of the recording medium S is neutralized by the neutralization section 62, and the recording medium S is sent out from the neutralization device 6 in a state in which most of the electric charge has been removed.

[0018] The order of neutralization of the recording medium S is not limited to the configuration in which the front surface is neutralized first and then the back surface is neutralized. For example, the neutralization units 61 and 62 may be interchanged so that the neutralization unit 61 is located downstream of the neutralization unit 62 in the conveying direction of the recording medium S, and the neutralization unit 61 may be configured to neutralize the back surface of the recording medium S and then the front surface.

[0019] As described above, this embodiment is a static elimination device 6 that removes electric charge from a recording medium S on which electric charge has been generated, and includes a static elimination unit 61 that applies a voltage V1 of opposite polarity to the charge (negative charge in this example) generated on one side of the recording medium S, and a static elimination unit 62 that applies a voltage V2 of opposite polarity to the charge (positive charge in this example) generated on the other side of the recording medium S.

[0020] As described above, the charge eliminating section 61 is provided on the upstream side or downstream side of the charge eliminating section 62 in the transport direction of the recording medium S.

[0021] These features make it possible to effectively remove electric charges even when a high resistance medium is used, and reduce sticking of the high resistance medium to the transport path, unevenness in the position when discharged onto the discharge tray, sticking of recording media to each other on the discharge tray, etc. As a result, good handling properties can be achieved even with high resistance media.

[0022] Moreover, the voltage V1 applied to the charge removing roller 61a and the voltage V2 applied to the charge removing roller 62b are preferably DC biases that are subjected to constant current control.

[0023] For example, when the static eliminator 6 is used in an image forming apparatus described later, it is provided after a fixing device for fixing a toner image onto a recording medium S. Since a recording medium heated to a high temperature by the fixing device is fed into the static eliminator 6, when the image forming apparatus is operated continuously, the temperature of the static eliminator rollers 61a, 62b increases through the recording medium, and the resistance of the static eliminator rollers 61a, 62b tends to decrease.

[0024] In the case of a DC bias controlled to a constant voltage, an excessive current flows when the resistance of the charge removing rollers 61a, 62b decreases as described above. In contrast, in the case of a DC bias controlled to a constant current, the current value is maintained regardless of the temperature change of the charge removing rollers 61a, 62b, so that charge can be removed appropriately even if the resistance changes.

[0025] As described above, in this embodiment, the voltages V1 and V2 are DC biases that are constant current controlled, which makes it possible to maintain good static elimination performance even if the resistance of the static elimination rollers 61a and 62b changes.

[0026] <Configuration of Image Forming Apparatus> Next, the configuration of the image forming apparatus according to the embodiment will be described with reference to Fig. 2. Fig. 2 is a schematic diagram of the image forming apparatus.

[0027] In this example, the description will be based on the configuration of an image forming apparatus that transfers a toner image developed on a photoconductor to an intermediate transfer belt, and then secondarily transfers the toner image from the intermediate transfer belt to a recording medium such as paper or film, but the configuration of the image forming apparatus is not limited to this. For example, the image forming apparatus may not include an intermediate transfer belt, and may directly transfer a toner image developed on a photoconductor to a recording medium.

[0028] The image forming apparatus 100 includes a transfer device 1, a high-voltage power supply 2, a fixing device 3, an image forming section 4, and a static eliminator 6.

[0029] The image forming unit 4 has tandem imaging units (yellow (Y), magenta (M), cyan (C), black (K)) 41, an intermediate transfer belt 42, etc. The image forming unit 4 forms an image written by an optical writing device as a toner image on the intermediate transfer belt 42 through an image creation process by the imaging units 41.

[0030] Specifically, the imaging unit (Y, M, C, K) 41 has four rotatable photosensitive drums (Y, M, C, K), and is provided with imaging elements around each photosensitive drum, including a charging roller, a developing machine, a primary transfer roller, a cleaner unit, and a static eliminator.

[0031] An image forming element functions in each photosensitive drum, and the image on the photosensitive drum is transferred onto intermediate transfer belt 42 by each primary transfer roller 43. Intermediate transfer belt 42 is disposed in the nip between each photosensitive drum and each primary transfer roller 43, stretched by drive roller 44 and driven roller 45.

[0032] The transfer device 1 includes a pair of repulsive rollers 1a and a secondary transfer roller 1b. The transfer device 1 transfers a toner image on an intermediate transfer belt 42 to a recording medium S that is conveyed in a conveying direction along a conveying path indicated by a dashed line in the figure. The transfer device 1 transfers the toner images (yellow (Y), magenta (M), cyan (C), and black (K)) on the intermediate transfer belt 42 to the recording medium S by contact pressure and an electrical repulsive force due to a voltage of the same polarity applied from a high-voltage power source 2 to the repulsive roller 1a.

[0033] The high-voltage power supply 2 applies a voltage V3 having the same polarity as the charge of the toner image transferred to the intermediate transfer belt 42 to the repulsive roller 1a of the transfer device 1. Here, the voltage V3 is an example of a "secondary transfer bias."

[0034] The recording medium S after the secondary transfer is transported to the fixing device 3, and the toner image is fixed onto the recording medium S by the fixing device 3. The fixing device 3 is, for example, a fixing device of a thermal fixing type, and has a fixing roller 31 and a pressure roller 32 that come into contact with each other to form a nip. The recording medium S to which the toner image has been transferred is transported to the nip between the fixing roller 31 and the pressure roller 32, whereby the recording medium S is heated and pressurized. As a result, the toner on the recording medium S melts, and the toner image is fixed onto the recording medium S.

[0035] The recording medium S on which the toner image has been fixed is conveyed to the static eliminator 6. The recording medium S used in the image forming apparatus 100 is not limited to paper such as plain paper or coated paper, but may also be a resin film or the like as long as the material has heat resistance sufficient to withstand the heat of fixing and affinity with the toner.

[0036] However, as mentioned above, resin film and the like have a higher volume resistivity than paper, so the charge generated by the transfer device 1 when the toner image is transferred remains on the resin film. In other words, in the case of plain paper, the generated charge quickly dissipates, so the plain paper is hardly charged after fixing, whereas in the case of resin film, the transfer history remains and the resin film is charged after fixing. As a result, problems occur such as the charged resin film sticking to the transport path, the orientation of the resin film discharged onto the discharge tray being misaligned, and resin films sticking to each other on the discharge tray.

[0037] Therefore, in the image forming apparatus 100 of the embodiment, a static eliminator 6 is provided after the fixing device 3, and static eliminator 6 eliminates static electricity from both the front and back sides of the recording medium S. Note that the configuration of static eliminator 6 is omitted because it is the same as the configuration described in FIG.

[0038] As described above, the present embodiment is an image forming apparatus having a transfer device 1 that applies a voltage V3 to the recording medium S to transfer a toner image to the recording medium S, a fixing device 3 that fixes the toner image transferred to the recording medium S to the recording medium S, and a static eliminator that removes electric charges generated by the transfer device 1 from the recording medium S on which the toner image is fixed, and is an image forming apparatus 100 that includes the static eliminator 6 described above. This makes it possible to provide an image forming apparatus that can achieve good handling even with a high resistance medium such as a resin film.

[0039] <Hardware configuration of image forming device> Next, the hardware configuration of the image forming apparatus 100 according to this embodiment will be described with reference to Fig. 8. Fig. 8 is a block diagram showing an example of the hardware configuration of the image forming apparatus 100 according to one embodiment of the present invention.

[0040] The control unit 80 has a CPU (Center Processing Unit) 81, a ROM (Read Only Memory) 82, a RAM (Random Access Memory) 83, an NVRAM (Non Volatile Random Access Memory) 84, an input / output device (I / O port) 85, a communication I / F (Interface) 86, etc., each of which is connected by a bus 87.

[0041] The CPU 81 is a calculation unit and controls the operation of the entire image forming apparatus 100. The ROM 82 is a read-only non-volatile storage medium and stores programs such as firmware. The RAM 83 is a volatile storage medium capable of reading and writing information at high speed and is used as a working area when the CPU 81 processes information. The NVRAM 84 is a non-volatile storage medium capable of reading and writing information and stores setting values ​​required for controlling each part of the image forming apparatus 100, such as a voltage value output from the static eliminator 6 according to the paper type. The program stored in the ROM 82 is read into the RAM 83, and the CPU 81 controls each part of the image forming apparatus 100 by performing calculations according to the program loaded into the RAM 83. In addition, the setting values ​​stored in the NVRAM 84 are used at that time.

[0042] The I / O port 85 is connected to the transfer device 1, high voltage power supply 2, fixing device 3, image forming unit 4, static electricity removal device 6, etc. of the image forming apparatus 100, receives the outputs of sensors provided in each of these units, and outputs signals for controlling the transfer device 1, high voltage power supply 2, fixing device 3, image forming unit 4, and static electricity removal device 6 based on the state of the input sensor signals. For example, in the case of the fixing device 3, an output signal from a thermistor, which is a temperature detection element not shown, is input to the I / O port 85, and the CPU 81 controls the fixing operation of the fixing device 3 by controlling the on / off of a heater not shown via the I / O port 85 based on the temperature indicated by the thermistor.

[0043] The communication I / F 86 is connected to the operation unit of the image forming apparatus 100, and the current (or voltage) value applied by the static eliminator 6 set on the operation unit is stored in the NVRAM 84. This current (or voltage) value is determined with reference to the secondary transfer bias. In the first static eliminator, the value is set to a value with an opposite polarity to the secondary transfer bias and an absolute value of about 90%, while in the second static eliminator, the value is set to a value with the same polarity as the secondary transfer bias and an absolute value of about 10%. Different values ​​may also be stored as correction values ​​according to the type of film paper used.

[0044] <Hardware configuration of static eliminator> FIG. 9 shows a hardware block diagram of the static eliminator 6.

[0045] The static eliminator 6 includes high-voltage power supplies 61c and 62c, each of which includes a DC high-voltage power supply 61c1 and an AC high-voltage power supply 61c2, and a DC high-voltage power supply 62c1 and an AC high-voltage power supply 62c2. The high-voltage power supplies 61c and 62c are controlled by a constant current method or a constant voltage method, but this embodiment shows an embodiment in which the high-voltage power supplies 61c and 62c are controlled by constant current control. The DC high-voltage power supply 61c1 receives an ON signal via an I / O port 85 and a current setting signal set by the CPU 81 based on a current value stored in the NVRAM 84. The DC high-voltage power supply 61c1 controls the voltage by performing feedback control based on a value detected by a current detection means (not shown) so that the current value is based on the received current setting signal, and stably outputs a voltage controlled based on the received ON signal. The AC high-voltage power supply 61c2 and the DC high-voltage power supply 62c1 and AC high-voltage power supply 62c2 on the high-voltage power supply 62c side operate in the same manner. The high voltage power supply 61c adds the output voltages of the DC high voltage power supply 61c1 and the AC high voltage power supply 61c2 and outputs the sum. Similarly, the high voltage power supply 62c adds the output voltages of the DC high voltage power supply 62c1 and the AC high voltage power supply 62c2 and outputs the sum.

[0046] <Control of static eliminator> FIG. 10 is a flowchart showing the control executed by the CPU 81 for the static eliminator 6. In FIG.

[0047] First, in step S101 (hereinafter referred to as S101), the CPU 81 receives information about the recording medium on which an image is to be formed via the communication I / F 86. In S102, it is determined whether the recording medium is film paper or not based on the received information about the recording medium. If it is determined to be film paper, the current value stored in the NVRAM 84 is read out in S103, and the current value to be set in the high-voltage power supplies 61c and 62c of the static eliminator 6 is confirmed. If it is determined not to be film paper, the current value to be set in the high-voltage power supplies 61c and 62c is set to 0A in S104. Thereafter, in S105, the image forming unit 4, the transfer device 1, the high-voltage power supply 2, the fixing device 3, etc. are controlled to perform the image forming operation. Then, in S106, the static eliminator 6 is controlled based on the current value set in S103 or S104. In the case of film paper, the current value set in S103 is set in the high-voltage power supplies 61c and 62c, and by turning them on, a voltage controlled to a predetermined current value is applied to the recording medium after fixing, thereby eliminating static electricity.

[0048] In this flowchart, 0A is set for anything other than film paper, but the static eliminator may be left off. Also, if necessary, a lower current may be set for anything other than film paper than that for film paper. Also, since there are various types of film paper, the set value may be adjusted according to each type.

[0049] <Comparison of charging conditions of recording media> Next, the charged state of the recording medium will be described with reference to Fig. 3 to Fig. 5. Fig. 3 is an explanatory diagram showing the charged potential distribution of a recording medium discharged without neutralization. Fig. 4 is an explanatory diagram showing an example of the charged potential distribution of a recording medium discharged after neutralization, and Fig. 5 is an explanatory diagram showing another example of the charged potential distribution of a recording medium discharged after neutralization.

[0050] In the image forming apparatus 100 as described above, the recording medium S that is discharged from the fixing device 3 without being subjected to static elimination exhibits the charge potential distribution as shown in Fig. 3, and the surface of the recording medium S is charged to approximately -550 V. The recording medium used was waterproof paper with PET (polyethylene terephthalate) films attached to both sides of the paper, and the discharged waterproof paper was placed on a grounded stainless steel flat plate, and the surface of the waterproof paper was scanned with the probe of the surface potential meter for measurement.

[0051] When the back side of the recording medium (waterproof paper) is measured, the absolute value is almost the same as that of the front side, and it is charged with the opposite polarity. When the recording medium is discharged in this charged state, the negative charge on the front side of the recording medium discharged first and the positive charge on the back side of the recording medium discharged second are electrostatically attracted to each other. Due to the effect of this electrostatic attraction, the recording medium discharged first is pushed out by the recording medium discharged second, causing problems such as not being neatly stacked on the discharge tray or the recording media sticking to each other on the discharge tray.

[0052] In the static elimination device 6 of the embodiment, a constant current controlled DC bias is applied to the static elimination roller 61a and the static elimination roller 62b. As an example, FIG. 4 shows a case where static elimination is performed using constant current control, with the secondary transfer bias being -72 μA, the first static elimination bias being 65 μA, and the second static elimination bias being -7 μA. As a result, as shown in FIG. 4, 50% or more of the charge potential distribution can be set to 0 V, and the sticking of the recording medium is also reduced. Note that an unused recording medium shows a charge potential distribution where 0 V is 100%, so it is ideal to obtain a sharp charge potential distribution near 0 V.

[0053] 5, a superimposed bias in which an AC component is superimposed on a DC component is applied to the static elimination roller 61a and the static elimination roller 62b. Specifically, a superimposed bias in which a sinusoidal AC bias with a frequency of 3 kHz and Vpp (peak-to-peak value) of 3 kV is superimposed on the above-mentioned DC bias is applied to the static elimination roller 61a and the static elimination roller 62b.

[0054] By using the superimposed bias, the charge potential distribution became sharper than when only the DC bias was applied as shown in Figure 4, and the sticking of the recording medium was further reduced. This is thought to be because, while only the DC bias generates discharge of one polarity, the superimposed bias also generates discharge of the opposite polarity, resulting in a sharper charge potential distribution. The appropriate conditions for the AC bias are a sine wave with a frequency of 1 to 4 kHz and a Vpp of 2 to 4 kV, and these may be changed as appropriate depending on the specifications.

[0055] As a method of adjusting the bias, for example, first, a bias is applied only to the charge removing roller 61a, and the absolute value is set to 100 V or less within a range in which the peak charge polarity of the charge potential distribution does not invert. Next, the charge removing roller 62b is also operated, and the peak of the charge potential distribution is set to be close to 0 V, thereby obtaining good results.

[0056] As described above, in this embodiment, the charge removal biases (voltages V1 and V2) applied to the charge removal rollers 61a and 62b are superimposed biases in which an AC component is superimposed on a DC component. This makes the charge potential distribution after charge removal sharper, improving charge removal performance.

[0057] <Image forming system configuration> FIG. 6 is a schematic diagram showing an example of an image forming system.

[0058] The image forming system 200 includes an image forming apparatus 100 and a static eliminator 6. In other words, the static eliminator 6 is not limited to being mounted in the image forming apparatus 100 as shown in Fig. 2, but may be provided as a device separate from the image forming apparatus 100 and connected to the rear stage of the image forming apparatus 100 as shown in Fig. 6. The configuration of each member is the same as that of Fig. 2, and therefore description thereof will be omitted.

[0059] As described above, the present embodiment provides an image forming apparatus 100 having a transfer device 1 that applies a transfer bias to a recording medium to transfer a toner image onto the recording medium, a fixing device 3 that fixes the toner image transferred onto the recording medium onto the recording medium, and an electrostatic elimination device that removes electric charges generated by the transfer device 1 from the recording medium onto which the toner image has been fixed, and the image forming system 200 includes the electrostatic elimination device 6 described above as the electrostatic elimination device. This makes it possible to provide an image forming system that can achieve good handling even with a high resistance medium.

[0060] FIG. 7 is a schematic diagram showing another example of the image forming system.

[0061] In addition to the configuration shown in FIG. 6, the image forming system 200 may be configured to include a post-processing device 5 that performs a predetermined process on the recording medium S downstream of the static elimination device 6 (downstream in the transport direction of the recording medium S from the static elimination device 6).

[0062] By providing the static eliminator 6, stacking problems of recording media, sticking to the transport path, and sticking of recording media to each other caused by static electricity are reduced, so by connecting a post-processing device 5 such as a finisher or stacker, it becomes possible to efficiently process recording media such as waterproof paper.

[0063] As described above, in this embodiment, the post-processing device 5 that performs a predetermined process on the recording medium is provided downstream in the recording medium transport direction from the static eliminator 6. This makes it possible to stably output a large amount of recording media to the post-processing device and stably process the recording media in the post-processing device, even when a high-resistance recording medium such as waterproof paper is used.

[0064] What has been described above is one example, and other embodiments, additions, modifications, deletions, and other changes can be made within the scope of what a person skilled in the art can imagine. As long as the effects of the present invention are achieved in any of the following aspects, they are included in the scope of the present invention.

[0065] [Aspect 1] Aspect 1 is a static elimination device (e.g., static elimination device 6) that removes electric charge from a recording medium on which electric charge has been generated, and is characterized by comprising a first static elimination unit (e.g., static elimination unit 61) that applies a first static elimination bias (e.g., voltage V1) of opposite polarity to the electric charge generated on one side of the recording medium, and a second static elimination unit (e.g., static elimination unit 62) that applies a second static elimination bias (e.g., voltage V2) of opposite polarity to the electric charge generated on the other side of the recording medium, to the other side of the recording medium.

[0066] [Aspect 2] A second aspect of the present invention is characterized in that in the first aspect, the first static electricity removing unit is provided on the upstream side or downstream side of the second static electricity removing unit in the transport direction of the recording medium.

[0067] [Aspect 3] A third aspect of the present invention is characterized in that in the first aspect, the first static elimination bias and the second static elimination bias are DC biases controlled under constant current control.

[0068] [Aspect 4] A fourth aspect of the present invention is characterized in that in the first aspect, the first static elimination bias and the second static elimination bias are superimposed biases in which an AC component is superimposed on a DC component.

[0069] [Aspect 5] Aspect 5 is an image forming apparatus having a transfer device (e.g., transfer device 1) that applies a transfer bias (e.g., voltage V3) to a recording medium to transfer a toner image to the recording medium, a fixing device (e.g., fixing device 3) that fixes the toner image transferred to the recording medium to the recording medium, and a charge removal device that removes charge generated by the transfer device from the recording medium on which the toner image is fixed, and is an image forming apparatus (e.g., image forming apparatus 100) that includes a charge removal device of any of aspects 1 to 4 (e.g., charge removal device 6) as the charge removal device.

[0070] [Aspect 6] Aspect 6 is an image forming system (e.g., image forming apparatus 100) having a transfer device (e.g., transfer device 1) that applies a transfer bias (e.g., voltage V3) to a recording medium to transfer a toner image to the recording medium, a fixing device (e.g., fixing device 3) that fixes the toner image transferred to the recording medium to the recording medium, and a charge removal device that removes electric charge generated by the transfer device from the recording medium on which the toner image is fixed, the image forming system (e.g., image forming system 200) having a charge removal device of any of aspects 1 to 4 (e.g., charge removal device 6) as the charge removal device.

[0071] [Aspect 7] A seventh aspect is characterized in that in the sixth aspect, a post-processing device (e.g., post-processing device 5) that performs a predetermined process on the recording medium is provided downstream of the static eliminator in the conveying direction of the recording medium. [Explanation of symbols]

[0072] 1. Transcription device 1a Repulsive roller 1b Secondary transfer roller 2 High voltage power supply 3 Fixing device 4. Image forming section 41 Imaging unit 42 Intermediate transfer belt 5 Aftertreatment Device 6 Static eliminator 61 Static electricity removal unit (first static electricity removal unit) 61a Antistatic roller 61b Antistatic roller 61c High voltage power supply 62 Static electricity removal section (second static electricity removal section) 62a Antistatic roller 62b Antistatic roller 62c High Voltage Power Supply 100 Image forming device 200 Image forming system S Recording medium V1 voltage (first charge removal bias) V2 voltage (second charge removal bias) V3 voltage (transfer bias)

Claims

1. A static elimination device for removing electric charges from a recording medium on which electric charges have been generated, comprising: a first charge removing unit that applies a first charge removing bias having a polarity opposite to that of the charge generated on one surface of the recording medium to one surface of the recording medium; a second charge removing unit that applies a second charge removing bias having a polarity opposite to that of the charge generated on the other surface of the recording medium to the other surface of the recording medium; A static elimination device comprising:

2. The static elimination device according to claim 1 , wherein the first static elimination unit is provided on the upstream side or downstream side of the second static elimination unit in a transport direction of the recording medium.

3. 2. The static elimination device according to claim 1, wherein the first static elimination bias and the second static elimination bias are DC biases controlled under constant current control.

4. 2. The static elimination device according to claim 1, wherein the first static elimination bias and the second static elimination bias are superimposed biases in which an AC component is superimposed on a DC component.

5. a transfer device that applies a transfer bias to a recording medium to transfer a toner image onto the recording medium; a fixing device that fixes the toner image transferred onto the recording medium to the recording medium; a charge removing device that removes electric charges generated by the transfer device from the recording medium on which the toner image is fixed; An image forming apparatus having An image forming apparatus comprising the static eliminator according to claim 1 .

6. a transfer device that applies a transfer bias to a recording medium to transfer a toner image onto the recording medium; an image forming apparatus having a fixing device that fixes the toner image transferred onto the recording medium to the recording medium; a charge removing device that removes electric charges generated by the transfer device from the recording medium on which the toner image is fixed; An image forming system having: An image forming system comprising the static eliminator according to claim 1 .

7. 7. The image forming system according to claim 6, further comprising a post-processing device for performing a predetermined process on the recording medium, the post-processing device being disposed downstream of the static eliminator in a conveying direction of the recording medium.

Images