De-electrification device and media processing device

Abstract

The present application provides a device for removing static electricity and a medium processing device. The device for removing static electricity includes a discharge electrode configured in a non-contact state with a medium and removing static electricity from the medium, and a power source that applies a discharge voltage including at least an alternating current component to the discharge electrode. When a conveying speed of the medium is v [mm / sec.] and a frequency of the discharge voltage is f [Hz], the following equation is satisfied: f / v ≥ 0.8 … (Equation 1).

Description

Technical Field

[0001] This disclosure relates to a de-energizing device for removing electricity from a medium and a medium processing apparatus using the de-energizing device. Background Technology

[0002] As such a current-removing device, current-removing devices are known, for example, as described in the following four patent documents.

[0003] Japanese Patent Application Publication No. 2016-157011 discloses an image forming system comprising: a charge control unit that charges the medium on which the image is formed by the image forming section in order to suppress the adhesion of the medium to each other; and an application current control unit that controls the current supplied to the charge control unit according to the temperature of the medium.

[0004] U.S. Patent No. 8,320,817(B2) discloses a static electricity removal device that removes static electricity from the surface of a charged sheet by means of a contact static electricity removal unit and from the back side of the charged sheet by means of a non-contact static electricity removal unit.

[0005] Japanese Patent Application Publication No. 2017-111392 discloses an image forming system comprising: a de-energizing component that de-energizes a medium; a voltage applying unit that applies a de-energizing voltage to the de-energizing component to cause a de-energizing current for de-energizing the medium to flow into the medium; and a control unit that, when the de-energizing voltage is applied to the de-energizing component, changes the transport speed of the medium, and changes the de-energizing voltage according to the change in transport speed, thereby changing the de-energizing current flowing in the medium.

[0006] Japanese Patent No. 6481219 discloses a deionization device comprising: a plurality of first discharge electrodes facing one side of a plate, arranged in a straight line substantially perpendicular to the moving direction of the plate, and subjected to a DC voltage; and a plurality of second discharge electrodes facing the first discharge electrodes across the plate, arranged in a straight line substantially perpendicular to the moving direction of the plate, and subjected to a DC voltage, wherein the first and second discharge electrodes reverse the polarity of their adjacent discharge electrodes, and the opposing first and second discharge electrodes reverse the polarity, thereby forming a structure in which positive and negative ions are mixed between adjacent discharge electrodes. Summary of the Invention

[0007] The technical problem to be solved by this disclosure is to provide a de-energizing device and a medium processing apparatus using the de-energizing device, wherein when de-energizing the medium in a non-contact state, the de-energizing parameters of the discharge voltage, which includes at least an AC component, applied to the discharge electrode are optimized, thereby achieving de-energizing that suppresses uneven discharge.

[0008] According to the first aspect of this disclosure, a current removal device is provided, wherein the current removal device comprises: a discharge electrode, which is configured in a non-contact state with a medium and removes electricity from the medium; and a power source, which applies a discharge voltage containing at least an AC component to the discharge electrode, wherein when the transport speed of the medium is v [mm / sec.] and the frequency of the discharge voltage is f [Hz], the following equation is satisfied: f / v≥0.8……(Equation 1).

[0009] According to the second aspect of this disclosure, in the current removal device, the current removal device satisfies the following formula:

[0010] f / v≥1.5……(Equation 2).

[0011] According to the third aspect of this disclosure, in the electrostatic removal device, the discharge electrode is covered by a housing having an opening in a region opposite to the medium. When the opening width of the housing in the direction of medium transport is L (mm), the following formula is satisfied:

[0012] f / v*L≥30……(Equation 3).

[0013] According to the fourth aspect of this disclosure, in the current removal device, the discharge electrode and the medium are shielded by a shielding member having a through hole, which exposes all or part of the discharge electrode.

[0014] According to the fifth aspect of this disclosure, the discharge electrode has one or more linear electrodes extending in an intersecting direction that intersects the transport direction of the medium, and the one or more linear electrodes are shielded from the medium by a shielding member having a through hole that exposes at least any one of the linear electrodes in any region along the length direction.

[0015] According to the sixth aspect of this disclosure, the discharge electrode has a plurality of linear electrodes extending in an intersecting direction that intersects the transport direction of the medium, the through holes intersect the plurality of linear electrodes in an inclined direction, and a plurality of them are arranged at predetermined intervals toward the length direction of the linear electrodes.

[0016] According to the seventh aspect of this disclosure, the shielding component is made of an insulating material.

[0017] According to the eighth aspect of this disclosure, the de-energizing device includes a control unit that controls the frequency of the discharge voltage according to the conveying speed of the medium.

[0018] According to the ninth aspect of this disclosure, a current removal device is provided, comprising: a non-contact current removal unit having a discharge electrode configured in a non-contact state to remove current from the medium, and a power supply for applying a discharge voltage containing at least an AC component to the discharge electrode, wherein when the transport speed of the medium is v [mm / sec.] and the frequency of the discharge voltage is f [Hz], f / v ≥ 0.8… (Equation 1); and a contact current removal unit disposed upstream of the non-contact current removal unit in the transport direction of the medium, and having a current removal component in contact with the transported medium, wherein the medium is removed from current by applying a voltage to the current removal component.

[0019] According to the tenth aspect of this disclosure, a medium processing apparatus is provided, comprising: a conveying unit for conveying a medium; a charging unit disposed midway along the conveying path of the medium to charge the medium; and a de-energizing device disposed downstream of the charging unit in the conveying direction of the medium to de-energize the medium charged by the charging unit.

[0020] (Effect)

[0021] According to the first scheme, when removing charge from the medium in a non-contact state, the charge removal parameters, which include at least an AC component in the discharge voltage applied to the discharge electrode, can be optimized, thereby achieving charge removal that suppresses discharge unevenness. In particular, compared to the case where the charge removal parameter is f / v < 0.8, charge removal without unevenness can be achieved.

[0022] According to the second scheme, compared with the case where the removal parameter is f / v < 1.5, it is possible to further achieve removal without unevenness.

[0023] According to the third scheme, the desired static electricity removal effect can be obtained regardless of the opening width of the casing.

[0024] According to the fourth scheme, contact between the dielectric and the discharge electrode can be suppressed, while reducing the deterioration of uneven discharge.

[0025] According to the fifth scheme, when the discharge electrode is one or more linear electrodes, it is possible to suppress the contact between the dielectric and the discharge electrode, and at the same time reduce the deterioration of uneven discharge.

[0026] According to the sixth scheme, when the discharge electrode is a plurality of linear electrodes, it is possible to suppress contact between the dielectric and the discharge electrode, and at the same time reduce the deterioration of uneven discharge.

[0027] According to the seventh scheme, current flow in the shielding component can be suppressed, thereby enabling the efficient supply of ions from the discharge electrode to the medium.

[0028] According to the eighth scheme, the electrostatic removal performance of the medium can be ensured, while the generation of unwanted noise or ozone can be suppressed.

[0029] According to the ninth scheme, after the surface charge of the medium is largely removed by the contact-type charge removal unit, the remaining charge can be removed non-contactly.

[0030] According to the 10th embodiment, a dielectric processing apparatus is provided that optimizes the discharge voltage, which includes at least an AC component, applied to the discharge electrode when removing charge from a dielectric in a non-contact state, thereby enabling the removal of charge that suppresses uneven discharge. Attached Figure Description

[0031] Figure 1 (a) is an explanatory diagram showing an outline of an embodiment of a medium processing apparatus using the current removal device of the present disclosure, and (b) is an explanatory diagram showing the main parts of the non-contact current removal unit shown in (a).

[0032] Figure 2 (a) is an explanatory diagram schematically showing an example of the charge distribution of multiple media stacked on the media discharge receiving section without using the charge removal device of the image forming apparatus of Embodiment 1; (b) is an explanatory diagram showing the operation of the charge removal device; and (c) is an explanatory diagram schematically showing an example of the charge distribution of multiple media stacked on the media discharge receiving section with the charge removal device.

[0033] Figure 3 This is an explanatory diagram showing the overall structure of the image forming apparatus according to Embodiment 1.

[0034] Figure 4 This is an explanatory diagram showing an example of the structure around the secondary transfer section and the static removal section of the image forming apparatus according to Embodiment 1.

[0035] Figure 5 (a) is an explanatory diagram showing a structural example of the contact-type eliminator used in Embodiment 1, (b) is an explanatory diagram showing another structural example of the contact-type eliminator used in Embodiment 1, and (c) is an explanatory diagram showing the state when the eliminator operation using the contact-type eliminator shown in (b) is not performed.

[0036] Figure 6 (a) is an explanatory diagram schematically showing the de-energizing operation using a contact-type energizer; (b) is an explanatory diagram showing the tendency of the change in the charged state of the medium accompanying the de-energizing operation using a contact-type energizer; (c) is an explanatory diagram schematically showing the de-energizing operation using a non-contact-type energizer; and (d) is an explanatory diagram showing the tendency of the change in the charged state of the medium accompanying the de-energizing operation using a non-contact-type energizer.

[0037] Figure 7 (a) is an explanatory diagram showing an example of the charged state of a medium, (b) is an explanatory diagram showing the de-energizing operation principle using a contact-type de-energizer, and (c) is an explanatory diagram showing the de-energizing operation principle using a non-contact-type de-energizer.

[0038] Figure 8 This is a flowchart illustrating the image production control processing procedure of the image forming apparatus of Embodiment 1.

[0039] Figure 9 (a) is shown Figure 8 The illustration shown is an example of the "method for determining the method of removing static electricity". (b) is an illustration of an example of measuring the surface resistance of a medium.

[0040] Figure 10 This is an explanatory diagram schematically illustrating the de-energizing operation process using the de-energizing device of Embodiment 1.

[0041] Figure 11 (a) is an explanatory diagram showing the structure of the dual-structure eliminator roller of the contact-type eliminator in Embodiment 1; (b) is an explanatory diagram showing the contact state between the dual-structure eliminator roller in part B of (a) and the medium; and (c) is an explanatory diagram showing the contact state between the dual-structure eliminator roller and the axial medium.

[0042] Figure 12 (a) is an explanatory diagram showing the significance of the contact between the dual-structure electrostatic roller and the medium and its contact pressure, and (b) is an explanatory diagram showing an example of a method for measuring the volume resistivity of the electrostatic roller.

[0043] Figure 13 (a) is an explanatory diagram showing an example of the installation of a surface potentiometer for measuring the surface potential of a medium, and (b) is an explanatory diagram showing the positional relationship between the surface potentiometer and the medium.

[0044] Figure 14 This is a flowchart illustrating an example of the bias control for a contact-type eliminator.

[0045] Figure 15 (a) is an explanatory diagram showing the change in charge of the medium during the de-energizing operation of the contact-type energizer, and (b) is an explanatory diagram schematically showing the charge state of the medium surface before and after de-energizing using the contact-type energizer.

[0046] Figure 16(a) is an explanatory diagram showing an example of the installation of a surface potentiometer for a contact-type eliminator; (b) is an explanatory diagram showing an example of a method for selecting the initial optimal value of the eliminator bias voltage using a surface potentiometer located downstream of the contact-type eliminator in the medium transport direction; and (c) is an explanatory diagram showing an example of a metering line using this method.

[0047] Figure 17 (a) is an illustration schematically showing the movement of charge from the discharge wire accompanying corona discharge using a non-contact eliminator; (b) is an illustration schematically showing an example of the voltage-current characteristics of corona discharge; and (c) is an illustration schematically showing the ion balance of an AC gridless electrode type eliminator (using AC discharge bias).

[0048] Figure 18 (a) is an explanatory diagram schematically showing an example of ion generation by a non-contact ion generator with a counter electrode; (b) is an explanatory diagram schematically showing an example of ion generation without a counter electrode; (c) is an explanatory diagram showing the ion generation process of the surface potential of the medium when using an AC ionization bias; and (d) is an explanatory diagram showing the ionization process of the surface potential of the medium when using a DC ionization bias.

[0049] Figure 19 (a) is a flowchart illustrating an example of the de-bias control of a non-contact de-bias device, and (b) is an explanatory diagram illustrating an example of the method for determining the frequency f of the de-bias Vd2.

[0050] Figure 20 This is an explanatory diagram showing the main parts of the image forming apparatus according to Embodiment 2.

[0051] Figure 21 This is an explanatory diagram showing an example of the structure around the current-removing section of the image forming apparatus in Embodiment 2.

[0052] Figure 22 (a) is an explanatory diagram showing an example of a energizing operation using a contact-type energizer without medium reversal, and (b) is an explanatory diagram showing an example of an energizing operation using a contact-type energizer with medium reversal.

[0053] Figure 23 (a) is an explanatory diagram showing the main parts of the non-contact type electric eliminator of variant 1, (b) is an explanatory diagram showing an example of the shielding member as viewed from direction B in (a), and (c) is an explanatory diagram showing the function of the shielding member.

[0054] Figure 24(a) is an explanatory diagram showing the main parts of the non-contact eliminator in variant 2, (b) is an arrow direction diagram of the non-contact eliminator viewed from direction B in (a), and (c) is an explanatory diagram showing a variant example of the non-contact eliminator shown in (b).

[0055] Figure 25 (a) is an explanatory diagram showing the waterfall development method for visualizing the surface charge distribution of a medium in Example 1, and (b) is an explanatory diagram showing an example of visualizing the surface charge distribution of a medium before de-energization, the surface charge distribution of a medium after passing through a contact-type de-energizer, and the surface charge distribution of a medium after passing through a non-contact-type de-energizer by the waterfall development method.

[0056] Figure 26 (a) is a graph showing the relationship between the applied voltage and the potential after de-energization under constant voltage control of the contact-type eliminator of Example 2, and (b) is a graph showing the relationship between the applied current and the potential after de-energization under constant current control of the contact-type eliminator of Example 2.

[0057] Figure 27 This is an explanatory diagram showing the relationship between the medium engagement variation and the stability of the current removal control of the dual-structure current removal roller in Example 3.

[0058] Figure 28 (a) is an explanatory diagram showing the relationship between the excitation parameter f / v and its evaluation results in the non-contact excitation device of Example 4; (b) is an explanatory diagram showing an example of changing the excitation parameter frequency f; (c) is an explanatory diagram showing an example of changing the excitation parameter f (frequency) / v (medium transport speed); and (d) is an explanatory diagram showing an example of changing the excitation parameter f (frequency) / v (medium transport speed) * L (housing opening width).

[0059] Figure 29 (a) is an explanatory diagram showing the evaluation method of Example 4, and (b) is an explanatory diagram showing the relationship between frequency and tensile load in the evaluation method of (a).

[0060] Figure 30 (a) is an explanatory diagram showing an example of the surface charge distribution of the de-energized medium when the de-energizing parameter f (frequency) / v (medium transport speed) is above a specified value in the non-contact de-energizer of Example 5, and (b) is an explanatory diagram showing an example of the surface charge distribution of the de-energized medium when the de-energizing parameter f / v is less than a specified value.

[0061] Figure 31 This is an explanatory diagram showing the relationship between electrode distance (equivalent to the distance between the discharge wire and the medium) and charge amount (equivalent to the surface charge of the medium) in the non-contact type eliminator of Embodiment 6. Detailed Implementation

[0062] ◎Summary of Implementation Methods

[0063] Figure 1 (a) shows an outline of an embodiment of a media processing apparatus using the current removal device of the present disclosure.

[0064] In this figure, the medium processing apparatus includes a conveying unit 13 for conveying medium S; a charging unit 14 disposed in the middle of the conveying path of medium S and charging medium S; and a de-energizing device 10 disposed downstream of the charging unit 14 in the conveying direction of medium S and de-energizing medium S charged by the charging unit 14.

[0065] Here, the medium processing apparatus is not limited to an image forming apparatus having an image forming section, but also includes those without an image forming section. Furthermore, the charging unit 14 naturally includes a transfer unit that applies a transfer voltage, and also includes a transport unit that is charged by friction during transport of the medium S.

[0066] In this example, such as Figure 1 As shown in (b), the de-energizing device 10 is characterized by comprising: a non-contact de-energizing unit 11, which has a discharge electrode 1 configured in a non-contact state to de-energize the medium S, and a power supply 2 that applies a discharge voltage containing at least an AC component 2a to the discharge electrode 1, wherein when the transport speed of the medium S is v [mm / sec.] and the frequency of the discharge voltage is f [Hz], f / v ≥ 0.8……(Equation 1); and a contact de-energizing unit 12, which has a de-energizing component 16 disposed at a position upstream of the non-contact de-energizing unit 11 in the transport direction of the medium S, and in contact with the transported medium S, and de-energizes the medium S by applying a voltage to the de-energizing component 16.

[0067] In this technical means, the discharge electrode 1 includes linear electrodes such as gridless electrode type electric charge and grid electrode type electric charge, as well as needle electrodes of so-called ion generator.

[0068] Furthermore, when the transport speed of medium S is relatively high, the ion balance deteriorates if the ion generation cycle (ion frequency) is not reduced. In this application, considering this, focusing on the de-energizing parameter f / v, which is the transport speed v of medium S and the frequency f of the discharge voltage containing AC components, and setting "0.8" as the boundary value based on the evaluation method for the adhesion of medium S described later, it is possible to achieve de-energizing without unevenness compared to the case where f / v < 0.8.

[0069] In addition, in this example, a wide-width current removal is performed using the contact-type current removal unit 12, thereby achieving the effect of uniformly balancing the amount of current removed using the non-contact-type current removal unit 11.

[0070] Assuming that the current removal process using the current removal devices (contact-type current removal unit 12 and non-contact-type current removal unit 11) in this example is not implemented, such as... Figure 2 As shown in (a), the surface potential of a high-resistivity dielectric S, such as a resin film, is charged to a - potential, and the back potential of the dielectric S is reversed to a + potential by dielectric polarization. When the dielectric S is stored in this stacked state, there is a concern that the dielectric S may stick to each other due to electrostatic forces.

[0071] However, if the current removal process is performed using the current removal device 10 (contact-type current removal unit 12, non-contact-type current removal unit 11) of this example, then as Figure 2 As shown in (b), even when using a high-resistivity dielectric S, the charge on the surface of the dielectric S passing through the contact-type current-removing unit 12 and the non-contact-type current-removing unit 11 is approximately zero. Consequently, the charge on the back side of the dielectric S is also approximately zero, thus... Figure 2 As shown in (c), even when the media S are stacked, the concern that the media S will stick to each other due to electrostatic forces can be eliminated.

[0072] Next, a representative or preferred embodiment of the current removal device 10 of this embodiment, especially the non-contact current removal unit 11, will be described.

[0073] First, as a preferred method for the removal parameter f / v, an example is given that f / v ≥ 1.5……(Equation 2). In this example, the frequency f of the removal bias voltage Vd2 is increased relative to the transport speed v of the medium S, thereby increasing the amount of ions provided per unit time of the moving area relative to the medium S.

[0074] In addition, while the aforementioned f / v is representative as a parameter for electrostatic removal, it is not limited to this. Other parameters that affect the electrostatic removal effect along with f / v can also be added.

[0075] Generally speaking, as a method of using a linear electrode as the discharge electrode 1, for example, a known corona discharger such as a gridless electrode type charged electrical device, in this method, the discharge electrode 1 is covered by a housing 5 having an opening 5a in the region opposite to the medium S, thereby presuming that the opening width L (mm) in the transport direction of the medium S in the opening 5a of the housing 5 affects the current removal effect.

[0076] In other words, the opening width L of the shell 5 restricts the ion emission region towards the medium S. When the opening width L is narrower, the ion emission region becomes narrower, and conversely, when the opening width L is wider, the ion emission region becomes wider. Therefore, the amount of ions per unit length can be adjusted by the relationship between the amount of ions and the ion emission region. Specifically, when the opening width L is longer, if the ion generation period (ion frequency) is not shortened, the ion balance of the entire region of the opening 5a may deteriorate.

[0077] Considering this, when selecting f / v*L as the power removal parameter, it is found that the following formula is preferred.

[0078] f / v*L≥30……(Equation 3)

[0079] Furthermore, from the viewpoint of preventing interference between the discharge electrode 1 and the dielectric S, it is preferable to... Figure 1 In (b), the discharge electrode 1 is shielded from the dielectric S by a shielding member 6, which has a through-hole 6a that exposes all or part of the discharge electrode 1. The discharge electrode 1 referred to here is not limited to a wire electrode, but also includes a needle electrode. In this example, the shielding member 6 prevents the dielectric S from contacting the discharge electrode 1. Furthermore, the through-hole 6a of the shielding member 6 exposes all or part of the discharge electrode 1 and functions as a pathway for ions generated around the discharge electrode 1 to move towards the dielectric S. However, if the opening area of ​​the through-hole 6a is too wide, the dielectric S can easily contact the discharge electrode 1; therefore, it is preferable to avoid making the opening area of ​​the through-hole 6a unnecessarily wide.

[0080] Here, in the case where the discharge electrode 1 has one or more linear electrodes extending in the cross direction of the medium S, as a preferred embodiment of the shielding member 6, it is exemplified by having a through hole 6a that exposes at least any one of the one or more linear electrodes in any region along the length direction.

[0081] In particular, in the configuration where the discharge electrode 1 has a plurality of linear electrodes extending in the intersecting direction of the dielectric S, it is preferable that the through-hole 6a of the shielding member 6 intersects the plurality of linear electrodes in the inclined direction, and that the plurality of linear electrodes are arranged at predetermined intervals relative to the length direction of the linear electrodes. This example is effective in that it is easy to construct a configuration in which at least any one of the plurality of linear electrodes is exposed in any region of the length direction.

[0082] Furthermore, as a preferred embodiment of the shielding member 6, it is exemplified that it is made of an insulating material. This example is effective in preventing the ions generated by the discharge electrode 1 from unnecessarily leaking onto the shielding member 6 side.

[0083] Furthermore, regarding the electrical parameters, they can be used fixedly, but in situations where the conveying speed v of the medium S varies, such as... Figure 1 As shown in (b), it is preferable to have a control unit 7 that controls the frequency f of the discharge voltage according to the conveying speed v of the medium S. Furthermore, in Figure 1 In (b), label 8 is the speed detection unit for detecting the conveying speed v of the medium S.

[0084] When the transport speed v of medium S is relatively fast, it is necessary to increase the frequency f of the discharge voltage Vd(f). However, when the transport speed v of medium S is relatively slow, the frequency f of the discharge voltage Vd(f) can be reduced, thereby suppressing the generation of noise or ozone accordingly.

[0085] The present disclosure will now be described in more detail with reference to the embodiments shown in the accompanying drawings.

[0086] ◎Implementation Method 1

[0087] Figure 3 The overall structure of the image forming apparatus of Embodiment 1 is shown.

[0088] -Overall structure of the image forming apparatus-

[0089] In this figure, the image forming apparatus 20 includes: an image forming unit 22 (specifically 22a to 22f) that forms multiple color component images (in this embodiment, white #1, yellow, magenta, cyan, black, and white #2) within an image forming apparatus housing 21; a strip-shaped intermediate transfer body 30 that sequentially transfers (first-time transfers) each color component image formed in each image forming unit 22 and holds each color component image; a secondary transfer apparatus 50 that transfers each color component image transferred on the intermediate transfer body 30 to a medium S; a fixing apparatus 70 that fixes the second-transfer image onto the medium S; and a medium transport system 80 that transports the medium S to the secondary transfer area. Furthermore, in this example, white #1 and white #2 use a completely identical white material, but different white materials can be used depending on whether they are located on a lower or higher layer than other color component images on the medium S. Alternatively, transparent materials can be used instead of white #1 and white #2, and other special colors can also be used.

[0090] -Image Formation Unit-

[0091] In this embodiment, each image forming unit 22 (22a to 22f) has a drum-shaped photoreceptor 23. Around each photoreceptor 23, there are charging devices such as gridless electrode type chargers or transfer rollers that charge the photoreceptor 23, light-exposing devices such as laser scanning devices that write electrostatic latent images on the charged photoreceptor 23, developing devices 26 that develop the electrostatic latent images written on the photoreceptor 23 using toners of various color components, primary transfer devices 27 that transfer the toner image on the photoreceptor 23 to an intermediate transfer body 30, and photoreceptor cleaning devices 28 that remove residual toners from the photoreceptor 23.

[0092] Furthermore, the intermediate transfer body 30 is mounted on multiple tension rollers 31 to 33. For example, the tension roller 31 is used as a drive roller driven by a drive motor (not shown in the figure), and the intermediate transfer body 30 is moved cyclically by the drive roller. Moreover, an intermediate transfer body cleaning device 35 is provided between the tension rollers 31 and 33 for removing residual toner from the intermediate transfer body 30 after secondary transfer.

[0093] -Secondary Transfer Device-

[0094] Furthermore, such as Figure 3 and Figure 4 As shown, the secondary transfer device 50 is configured such that the transfer conveyor belt 53 is stretched on multiple stretcher rollers 52 (specifically 52a, 52b) to form a belt transfer module 51, which is in contact with the surface of the intermediate transfer body 30.

[0095] Here, the transfer conveyor belt 53 uses materials such as chloroprene with a volume resistivity of 10. 6 ~10 12 A semi-conductive strip with an Ω·cm is used to configure a tension roller 52a as an elastic transfer roller 55, and the elastic transfer roller 55 is pressed and arranged with the intermediate transfer body 30 in the secondary transfer domain TR via the transfer conveyor belt 53. The tension roller 33 of the intermediate transfer body 30 is arranged opposite to the opposing roller 56 constituting the opposing electrode of the elastic transfer roller 55, thereby forming a transport path of the medium S from the position of one tension roller 52a to the position of the other tension roller 52b.

[0096] Furthermore, in this example, the elastic transfer roller 55 is configured such that an elastic layer formed by foamed polyurethane rubber or EPDM mixed with carbon black is coated around the metal shaft.

[0097] Furthermore, the transfer bias voltage Vt from the transfer power supply 58 is applied to the opposing roller 56 (which also serves as the tension roller 33 in this example) via the conductive power supply roller 57. On the other hand, the elastic transfer roller 55 (one tension roller 52a) is grounded via a metal shaft not shown in the figure, thereby forming a predetermined transfer electric field between the elastic transfer roller 55 and the opposing roller 56. In addition, another tension roller 52b is also grounded to prevent the transfer conveyor belt 53 from becoming charged. Moreover, considering the peelability of the medium S at the downstream end of the transfer conveyor belt 53, it is effective to make the downstream tension roller 52b smaller in diameter than the upstream tension roller 52a.

[0098] -Fixing device-

[0099] The fixing device 70 includes a heated fixing roller 71 that is configured to be in contact with the image holding surface of the medium S and is capable of being driven to rotate, and a pressure fixing roller 72 that is configured to press against the heated fixing roller 71 and rotates in tandem with the heated fixing roller 71. The image held on the medium S is passed through the pressing area between the two fixing rollers 71 and 72, thereby heating and pressing the image for fixing. Furthermore, the fixing method of the fixing device 70 is not limited to the method shown in the embodiment; non-contact fixing methods, laser-based fixing methods, etc., may also be appropriately selected.

[0100] -Media Transport System-

[0101] Furthermore, the media transport system 80 has multiple (two-stage in this example) media supply containers 81 and 82, so that the media S supplied from either of the media supply containers 81 and 82 is transported from the vertical transport path 83 extending in a generally vertical direction to the secondary transfer area TR via the horizontal transport path 84 extending in a generally horizontal direction. Then, the media S holding the transferred image is transported via the conveyor belt 85 to the fixing part of the fixing device 70 and discharged to the media discharge receiving part 86 provided on the side of the image forming apparatus housing 21.

[0102] Furthermore, the media transport system 80 has a reversible branch transport path 87 that branches downward from the downstream side of the fixing device 70 in the media transport direction in the horizontal transport path 84. Media S reversing in this branch transport path 87 returns to the horizontal transport path 84 via the return transport path 88 and then from the vertical transport path 83, thereby transferring an image on the back side of the media S in the secondary transfer area TR, and discharging it to the media discharge receiving unit 86 via the fixing device 70. Moreover, a media reversing mechanism 89 is provided midway through the branch transport path 87 to reverse the media S passing through the horizontal transport path 84 and discharge it to the media discharge receiving unit 86. This media reversing mechanism 89 has a branch return transport path 90 that branches off midway from the branch transport path 87 and transports the reversed media S towards the media discharge receiving unit 86. Switching gates 91 and 92 are respectively provided at the boundary between the horizontal transport path 84 and the branch transport path 87, and at the boundary between the branch transport path 87 and the branch return transport path 90, thereby reversing the media S passing through the horizontal transport path 84 and discharging it to the media discharge receiving unit 86.

[0103] In addition, the media transport system 80 is equipped with an alignment roller 93 for aligning the media S and supplying the media S to the secondary transfer area TR, and also has an appropriate number of transport rollers 94 in each transport path 83, 84, 87, and 88. Furthermore, a manual media feeder 95 is provided on the opposite side of the media discharge receiving section 86 of the image forming apparatus housing 21, which allows for manual supply of media toward the horizontal transport path 84.

[0104] -Basic Structure of Electrostatic Removal Device-

[0105] In this embodiment, a de-energizing device 100 is provided in the horizontal transport path 84 from the fixing device 70 to the medium discharge receiving unit 86, at a position upstream of the transport direction of the medium S compared to the branch transport path 87 of the medium reversal mechanism 89.

[0106] In this example, the de-energizing device 100 includes: a contact-type de-energizer 101 that contacts the medium S to de-energize more than half of the charge carried by the medium S; and a non-contact-type de-energizer 102 that is located downstream of the contact-type de-energizer 101 in the transport direction of the medium S and de-energizes the remaining charge of the medium S after it has been de-energized by the contact-type de-energizer 101 in a non-contact state.

[0107] The following describes the contact-type eliminator 101 and the non-contact-type eliminator 102.

[0108] <Contact-type eliminator>

[0109] like Figure 3 , Figure 4 as well as Figure 5As shown in (a), the contact-type eliminator 101 is configured to contact the dual-structure eliminator rollers 111 and 112. The driving force from the drive motor 113 is transmitted to either eliminator roller via a drive transmission mechanism 114 such as gears. By bringing the eliminator roller 111 into contact with the eliminator roller 112, the eliminator roller 111 follows the eliminator roller 112, thereby clamping and conveying the medium S between the eliminator rollers 111 and 112.

[0110] Furthermore, in this example, one de-energizing roller 111 is connected to a de-energizing power supply 115 and is subjected to a de-energizing bias voltage Vd1 (in this example, a positive DC voltage) from the de-energizing power supply 115, while the other de-energizing roller 112 is grounded.

[0111] In addition, regarding the setting of the power supply 115 for power removal, it can be used on either the front or back side of the medium S. When it is configured on the back side of the medium S, the polarity of the power removal bias voltage or power removal current used is opposite to that used when it is configured on the front side of the medium S.

[0112] In particular, as a different approach from this example, such as Figure 5 As shown in (b) and (c), the contact-type eliminator 101 is provided with a contact / separation mechanism 116 for contacting / separating one eliminator roller 111 from another eliminator roller 112. The contact / separation mechanism 116 used in this example has, for example, a swing arm 117 that swings around a swing fulcrum. The eliminator roller 111 is supported at the front end of the swing fulcrum away from the swing arm 117 so that it can rotate. The swing arm 117 is swung clockwise or counterclockwise by a drive source 118 such as a drive motor, thereby positioning the eliminator roller 111 in a non-contact retracted position or a contact position relative to the eliminator roller 112.

[0113] <Non-contact type electric shock remover>

[0114] In this example, for example, Figure 4 As shown, the non-contact eliminator 102 has an eliminator housing 121 with a channel cross-sectional shape that opens towards the front side of the medium S conveyed along the horizontal conveying path 84. A discharge wire 122 is installed along the length of the eliminator housing 121, and the discharge wire 122 is connected to an eliminator power supply 125. An eliminator bias voltage Vd2 is applied from the eliminator power supply 125 (in this example, an AC power supply 126 with an output AC voltage component and a DC power supply 127 with an output DC voltage component are used). Figure 6 On the other hand, a grounding electrode 123, which is made of a grounded metal plate, is disposed on the back side of the dielectric S.

[0115] Furthermore, in this example, only one discharge wire 122 is used, but it is not limited to this; multiple discharge wires 122 can also be used. Also, in this example, a so-called gridless electrode type charge carrier is used, but it is not limited to this; of course, a grid plate as a control electrode can be added to the opening facing the charge-eliminating housing 121 (a so-called grid electrode type charge carrier). Alternatively, a needle-shaped electrode, described later, can be used instead of the discharge wire 122. Moreover, regarding the placement of the charge-eliminating power supply 125, it can be placed on either the front or back side of the medium S, or it can be placed on both sides.

[0116] <Electricity removal characteristics of various electrostatic precipitators>

[0117] Here, the electrostatic removal characteristics of each electrostatic precipitator 101 and 102 are briefly explained.

[0118] Now, assuming the medium S is a high-resistivity (dielectric) film such as a resin film, for example, the medium S passing through the secondary transfer device 50 is charged by the transfer electric field. In this case, as... Figure 6 (a), (b) and Figure 7 As shown in (a), assuming the surface potential of medium S is negative Vc1(-), then on the back side of medium S, the positive charge e+ is induced to polarize.

[0119] In this state, the contact-type eliminator 101 applies an elimination bias voltage Vd1 to an elimination roller 111, such as Figure 7 As shown in (b), corona discharge occurs before and after the contact area (engagement area) CN between one de-electrostatic roller 111 and another de-electrostatic roller 112. Specifically, in this example, the medium S with a higher surface potential before de-electrostatic discharge enters the gap on the inlet side (corresponding to the upstream side of the conveying direction of the medium S) of the contact area CN of the de-electrostatic rollers 111 and 112, thereby mixing to generate a large current discharge Hb in the region far from the contact area CN and a weak current discharge Hs in the region close to the contact area CN. The medium S with a lower surface potential after de-electrostatic discharge passes through the gap on the outlet side (corresponding to the downstream side of the conveying direction of the medium S) of the contact area CN of the de-electrostatic rollers 111 and 112, thereby generating a weak current discharge Hs in the region close to the contact area CN. As a result, a positive charge is imparted to the surface of the charged medium S by a predetermined amount, and the negative charge e- on the surface of the medium S is de-electrostatically removed with the amount of charge imparted. In this state, as the surface charge of the medium S decreases, the dielectric-polarized positive charge e+ on the back side of the medium S also decreases. Therefore, as... Figure 6As shown in (b), the surface potential of the medium S decreases from Vc1(-) by the absolute value of ΔVc1. The contact-type eliminator 101 can ensure that the absolute value of ΔVc1 is relatively large to a certain extent as the amount of electricity removed. Therefore, the deviation of the surface potential of the medium S after electricity removal is relatively large, and there is a tendency for the electricity removal to be uneven.

[0120] On the other hand, regarding the static elimination characteristics of the non-contact static eliminator 102, such as Figure 6 As shown in (c) and (d), assuming the surface potential of the medium S is negative Vc2(-), the non-contact eliminator 102 applies a eliminator bias voltage Vd2 (an AC voltage component overlapping a DC voltage component) to the discharge wire 122, such as... Figure 7 As shown in (c), an AC corona discharge occurs between the discharge wire 122 and the charge-removing housing 121, thereby generating positive ions (+) and negative ions (-) around the discharge wire 122. As a result, the positive ions (+) and negative ions (-) generated by the corona discharge are drawn to the surface of the charged medium S by the electric field of the medium S. The amount of positive ions (+) provided removes the negative charge e- on the surface of the medium S, and the amount of negative ions (-) provided removes the positive charge e+ on the surface of the medium S. Furthermore, the back side of the medium S becomes 0 potential via the ground electrode 123, so the charge e+ on the dielectrically polarized back side of the medium S easily escapes to the ground electrode 123. Therefore, as... Figure 6 As shown in (d), the surface potential of the medium S decreases from Vc2(-) by the absolute value of ΔVc2. However, even if the non-contact eliminator 102 cannot ensure that the absolute value of ΔVc2 is so large as the amount of electricity removed, the deviation of the surface potential of the medium S after electricity removal is also small, so that electricity removal can be performed uniformly.

[0121] -Electrification Control System-

[0122] In this embodiment, such as Figure 4 As shown, the energizing device 100 (contact energizer 101, non-contact energizer 102) determines whether energization is required via the energization control system 130, and decides on the energization method and energization conditions if energization is required, thereby performing the energization action.

[0123] In this example, such as Figure 4 As shown, the power removal control system 130 includes a control device 131, for example, composed of a microcomputer, which is connected to the operation panel 140 of the image forming apparatus 20 and an environmental sensor 145 that detects environmental conditions (e.g., temperature, humidity). Furthermore, the control device 131 is selectively connected to the power supplies 115 and 125 for power removal of each of the power removal devices 101 and 102 via selector switches 132 and 133.

[0124] Here, the operation panel 140 is provided with a start switch for initiating image production processing using the image forming apparatus 20 (in Figure 4 (In this document, "SW" represents "switch," and the same applies below) 141, a mode selection switch 142 for selecting various image production modes (single-sided / double-sided printing mode, standard / high-definition printing mode, etc.), and a property indication switch 143 for indicating the physical properties (resistance, thickness, basis weight, size, etc.) of the medium S. Furthermore, regarding the physical properties of the medium S, detectors for detecting the physical properties (resistance, thickness, size, etc.) of the medium S can, for example, be installed in the medium supply containers 81, 82, or the transport path, and the physical property information of the medium S can be obtained through these detectors.

[0125] -Image forming apparatus for image production and processing-

[0126] Next, according to Figure 8 The flowchart shown illustrates the image production process of the image forming apparatus of this embodiment.

[0127] First, such as Figure 3 and Figure 4 As shown, when the start switch 141 is turned on, the image forming apparatus 20 begins the printing operation. In this state, the medium S is supplied from the medium supply container 81 or 82 or the manual medium supply device 95. On the other hand, the image forming unit 22 performs image processing to transfer the image to the medium S, and the image is moved to the secondary transfer domain TR via the intermediate transfer body 30.

[0128] Then, the medium S is conveyed to the secondary transfer field TR via the horizontal transport path 84, thereby performing the transfer operation using the secondary transfer device 50. After that, the medium S with the transferred image passes through the fixing device 70, and the image is fixed on the medium S. The medium S with the image fixed then goes to the power removal device 100.

[0129] In this state, the control device 131 reads the physical property information (e.g., medium type) of the medium S based on indication information from the operation panel 140, such as the physical property indicator switch 143, and thus determines whether it is necessary to use the current removal device 100 for current removal. As a method for this determination, for example, it observes whether the surface resistance of the medium S is at a level requiring current removal (e.g., 10) based on the physical property information (e.g., medium type). 11 If the surface resistance of the medium S is Ω / □ or higher, and the medium S is at a level requiring voltage removal, then voltage removal is deemed necessary. However, for internal processing, it is not always necessary to determine the surface resistance of the medium S; voltage removal can be determined solely based on the type of medium.

[0130] In this example, during the aforementioned determination process of whether de-energization is required, if it is determined that de-energization is required, the medium S undergoes de-energization processing using the de-energization device 100 and is transported. If it is determined that de-energization is not required, the medium S does not undergo de-energization processing using the de-energization device 100 and is transported toward the medium discharge receiving unit 86.

[0131] Here, in this embodiment, the contact-type eliminator 101 is in Figure 5 In the manner shown in (a), the de-energizing rollers 111 and 112 remain in contact regardless of whether de-energization is required. However, in this example, a de-energizing bias voltage Vd1 is applied when de-energization is required, and not applied when de-energization is not required.

[0132] On the other hand, the contact-type eliminator 101 in Figure 5 In the manner shown in (b) and (c), the dual-structure electric stripping rollers 111 and 112 are kept in contact when electric stripping is required, and are kept in non-contact state by the contact / separation mechanism 116 when electric stripping is not required.

[0133] Next, the procedures for situations requiring de-energization will be explained.

[0134] In this example, when it is determined that power removal is required, the control device 131 determines the power removal method and the power removal conditions.

[0135] <Decision on the method of static electricity removal>

[0136] In this example, the control device 131 identifies the physical property information (e.g., type of medium) of the medium S based on indication information from the property indicator switch 143, thereby, for example, Figure 9 As shown in (a), determine whether the surface resistance (Ω / □) of dielectric S is low, medium, or high. Here, low resistance is 10. 11 More than or less than 10 13 The resistance is 10. 13 More than or less than 10 15 High resistance is 10 15 More than or less than 10 18 .

[0137] Furthermore, in this example, based on the viewpoint of suppressing power consumption to the minimum required level, the following approach is adopted: when the surface resistance of the medium S is low, both selector switches 132 and 133 are open, and neither the contact-type eliminator 101 nor the non-contact-type eliminator 102 is selected. In addition, when the surface resistance of the medium S is medium, selector switch 132 is open and selector switch 133 is closed, and only the non-contact-type eliminator 102 is selected. Furthermore, when the medium S is high, both selector switches 132 and 133 are closed, and both the contact-type eliminator 101 and the non-contact-type eliminator 102 are selected.

[0138] However, from the viewpoint of improving the current removal accuracy of the current removal device 100, it is of course possible to use both the contact-type current collector 101 and the non-contact-type current collector 102 for any of the following: low resistance, medium resistance, and high resistance. Moreover, in this example, the method of selecting only the contact-type current collector 101 is not provided, but it is also possible to select only the contact-type current collector 101 in the case of, for example, medium resistance.

[0139] In this example, the surface resistance of the medium S is determined based on the indication information from the property indicator switch 143, but it is not limited to this method. For example, it could also use... Figure 9 The resistance measurement circuit 150 shown in (b) is used to determine the surface resistance of the dielectric S. Figure 9 In the resistance measurement circuit 150 shown in (b), dual-structure measuring rollers 151 and 152 are arranged along the conveying direction of the medium S. One of the dual-structure measuring rollers 151 located upstream in the conveying direction of the medium S is connected to the measuring power supply 153, and the other is grounded via a resistor 154. An ammeter 155 is installed between one of the dual-structure measuring rollers 152 located downstream in the conveying direction of the medium S and the ground wire. Alternatively, the conveying component of the medium S (alignment roller 93 or conveying roller 94) can also be used as measuring rollers 151 and 152, or the measuring rollers 151 and 152 can be arranged separately from the conveying component.

[0140] In this example, for instance, assuming that any medium with low resistance, medium resistance, or high resistance is used as medium S, but when medium S is high resistance, even if medium S is configured to span between the measuring rollers 151 and 152 of the dual structure, the measuring current from the measuring power supply 153 flows across the measuring rollers 151 of the dual structure and hardly flows through medium S to reach the ammeter 155 on the measuring roller 152 side.

[0141] In contrast, when the medium S has medium or low resistance, the surface resistance of these media S is smaller compared to that of the high-resistance medium S. Therefore, when the medium S is configured to span between the double-structure measuring rollers 151 and 152, a portion of the measuring current from the measuring power supply 153 flows across the double-structure measuring roller 151, and the remaining current of the measuring current flows through the medium S to the ammeter 155 on the measuring roller 152 side. Thus, the surface resistance of the medium S is calculated by the measuring current measured by the ammeter 155 and the applied voltage of the measuring power supply 153.

[0142] Alternatively, regarding this resistance measurement circuit 150, an ammeter can be positioned between the elastic transfer roller 55 of the secondary transfer device 50 and the ground wire, and the transfer current can be measured by the ammeter. The system resistance of the secondary transfer domain TR can be calculated based on the transfer bias voltage and the transfer current, thereby calculating the surface resistance of the dielectric S.

[0143] <Determination of Electrostatic Conditions>

[0144] Next, the method for determining the de-energization conditions in this example will be explained.

[0145] In this example, such as Figure 4 and Figure 9 As shown, the control device 131 calculates the surface resistance of the medium S based on the transfer conditions of the secondary transfer device 50 (e.g., correcting the transfer bias voltage Vt of the constant voltage control mode based on environmental information from the environmental sensor 145), and further calculates the surface resistance of the medium S based on the indication information (e.g., medium type) from the property indicator switch 143, thereby predicting the charged potential of the medium S passing through the secondary transfer device 50. Alternatively, the surface potential of the medium S charged by the secondary transfer device 50 can be measured using a potential probe (not shown).

[0146] Furthermore, the removal condition for the contact-type eliminator 101 is determined by reducing the absolute value of the predicted or measured surface potential Vc of the medium S by more than half (in this example, the target surface potential is Vc1). Similarly, the removal condition for the non-contact-type eliminator 102 is determined by the removal condition of the contact-type eliminator 101 (the target surface potential Vc1 of the medium S), thereby making the surface potential of the medium S Vc2 (approximately 0 in this example).

[0147] In addition, in this example, the method of making the de-energizing conditions of the non-contact type energizer 102 dependent on the de-energizing conditions of the contact type energizer 101 is adopted, but it is not limited to this. Of course, it is also possible to adopt a method of, for example, pre-determining the de-energizing conditions of the non-contact type energizer 102, so that the de-energizing conditions of the contact type energizer 101 depend on the de-energizing conditions of the non-contact type energizer 102.

[0148] Once the method and conditions for removing static electricity are determined, appropriate static electricity removal treatment is carried out based on the surface resistance of the medium S.

[0149] For example, in the case where the dielectric S is a high-resistivity medium such as a resin film, Figure 9 As shown in (a), the current removal method uses both a contact-type precipitator 101 and a non-contact precipitator 102, as follows: Figure 8 As shown, bias voltages Vd1 and Vd2, which are determined by the de-energizing conditions, are applied respectively.

[0150] In this state, such as Figure 8 and Figure 10 As shown, the surface of the medium S carries a negative charge e- through the secondary transfer device 50, and the back side of the medium S carries a positive charge e+ through dielectric polarization. First, it undergoes a de-energizing process using a contact-type de-energizer 101, reducing the absolute value of the surface potential Vc of the medium S by more than half, thus becoming Vc1. However, at this stage, the deviation of the surface potential Vc1 of the medium S is relatively large.

[0151] Then, the medium S passing through the contact-type eliminator 101 is further subjected to de-energization treatment using the non-contact-type eliminator 102, thereby reducing the surface potential of the medium S from Vc1 to Vc2 (approximately 0). During this stage, the surface potential Vc2 of the medium S is uniformly de-energized.

[0152] In particular, in this example, when the power removal of the contact-type eliminator 101 is enhanced, the deviation of the charged potential of the medium S after the power removal process of the contact-type eliminator 101 is increased. Therefore, it is preferable to enhance the power removal of the non-contact-type eliminator 102.

[0153] Furthermore, when the dielectric S has a medium resistance, such as Figure 9 As shown in (a), the de-energizing method uses only the non-contact type de-energizer 102 and applies a de-energizing bias voltage Vd2 determined as the de-energizing condition, thereby performing de-energizing processing using the non-contact type de-energizer 102. At this time, the surface potential of the medium S is de-energized from Vc to Vc2 (approximately 0). Furthermore, in this example, the contact type de-energizer 101 is not used, therefore, for example in… Figure 5 In the case shown in (b) and (c), the electric rollers 111 and 112 are positioned to retract from the medium S.

[0154] Furthermore, when the dielectric S has low resistance, such as Figure 9 As shown in (a), the current removal method does not apply to either the contact-type current collector 101 or the non-contact-type current collector 102, and no current removal process is performed, but the surface potential of the medium S is naturally removed.

[0155] -Construction of the eliminator roller in a contact-type eliminator-

[0156] like Figure 11 As shown, in this example, the de-energizing rollers 111 and 112 are both configured such that an elastic layer 171, formed by mixing polyurethane foam rubber or EPDM with carbon black, is coated around the metal shaft 170, and the surface of the elastic layer 171 is covered with a protective layer 172, such as fluororesin. Furthermore, a de-energizing bias voltage Vd1 from the de-energizing power supply 115 is applied to the metal shaft 170.

[0157] In this example, from the viewpoint of electrical discharge characteristics, the ASKERC hardness of the elastic layer 171 is preferably 50 to 90 degrees, more preferably 60 to 80 degrees. Here, ASKERC hardness refers to the rebound hardness under a load of 200g, and is measured by the following method: The measurement is performed using an industry-standard ASKERC type hardness tester manufactured by Polymer Instruments Co., Ltd., for measuring the hardness of soft rubber, sponge, etc., according to JIS-K7312 and JIS-S6050.

[0158] According to this embodiment, both the electrostatic removal rollers 111 and 112 have an elastic layer 171, thereby contacting both sides of the medium S along the axial direction through a contact area CN when the medium S is clamped and conveyed. Therefore, even if at least one of the electrostatic removal rollers 111 and 112 is inclined relative to the axial direction, as long as the inclination angle is small, the contact state between the electrostatic removal rollers 111 and 112 and the surface of the medium S is maintained. Therefore, corona discharge is stably implemented between the electrostatic removal rollers 111 and 112 and the surface of the medium S in the gaps CNf and CNr before and after the contact area CN between the two electrostatic removal rollers 111 and 112 and the medium S.

[0159] Furthermore, such as Figure 11 As shown in (c), the destatic rollers 111 and 112 contact both sides of the medium S through the elastic deformation of the elastic layer 171 in a contact area CN along the axial direction. Therefore, there is less concern that a portion of the destatic rollers 111 and 112 will not be in contact with the surface of the medium S in the axial direction. Thus, when the destatic rollers 111 and 112 engage and convey the medium S, no non-contact portion will be generated in a portion of the contact area CN extending along the axial direction. As a result, the contact area CN between the destatic rollers 111 and 112 maintains contact with the medium S in the axial direction, and there is no need to worry about uneven destatic removal in the axial direction.

[0160] <Example of non-contact configuration of electrostatic eliminator roller>

[0161] In addition, in this embodiment, the electric rollers 111 and 112 are also configured to contact when the medium S is not passing through, but this is not necessarily the case; for example, they can also be configured to contact. Figure 12As shown in (a), when the medium S is not passing through, the de-energizing rollers 111 and 112 are configured to be non-contact. However, the gap g between the de-energizing rollers 111 and 112 can be set to be narrower than the thickness ts of the medium S. When the medium S passes between the de-energizing rollers 111 and 112, the de-energizing rollers 111 and 112 contact the two surfaces of the medium S, thereby ensuring the conveying performance of the de-energizing rollers 111 and 112 on the medium S with the contact pressure Fd relative to the medium S in the contact domain CN. Furthermore, the rollers can be appropriately selected as long as it does not impair the range of de-energizing operation for the medium S.

[0162] In this example, the contact pressure Fd of the electrostatic eliminators 111 and 112 relative to the medium S is selected to be lower than the contact pressure of the secondary transfer device 50 in the secondary transfer domain TR. Therefore, when the medium S passes through the contact-type electrostatic eliminator 101, the image formed on the medium S is not unnecessarily damaged, thereby ensuring the transportability and electrostatic eliminator operation of the medium S.

[0163] <Volume resistivity of the elastic layer>

[0164] Furthermore, the volume resistivity of the elastic layer 171 is preferably 10. 4 10 Ω·cm or more 10 Ω·cm or less, more preferably 10 5 10 Ω·cm or more 9 Ω·cm or less, more preferably 10 6 10 Ω·cm or more 8 Below Ω·cm, the most preferred value is within this range even with environmental changes.

[0165] Here, the method for measuring volume resistivity can also be appropriately selected, for example... Figure 12 (b) shows an example.

[0166] In this figure, with one of the electrifying rollers 111 and 112 placed on the metal plate 180, and a predetermined load (e.g., 500g) applied to the ends of the metal shaft 170 (the core mold of the conductive roller) at points A1 and A2, for example, at a temperature of 22°C and a humidity of 55% RH, a predetermined applied voltage (e.g., 1000V) is applied between the metal shaft 170 and the metal plate 180, and the current value I (A) is read after 10 seconds using a current meter 181. The volume resistivity R (Ω) is calculated using the formula "R = V / I". The conductive roller, one of the electrifying rollers 111 and 112, is rotated 90° circumferentially at each of the four locations to perform this measurement and calculation, and the average value is taken as the volume resistivity R of the conductive roller. Then, based on the volume resistivity R of the conductive roller, the volume resistivity ρv (Ω·cm) of the elastic layer 171 is calculated using the following formula.

[0167] Formula ρv=D×W×R / t

[0168] In the above formula, D (cm) represents the axial length of the conductive roller, W (cm) represents the contact (engagement) width between the conductive roller and the electrode (equivalent to metal plate 180), and t (cm) represents the thickness of the elastic layer. The volume resistivity is calculated using the above formula.

[0169] <Discharge bias control for contact-type eliminators>

[0170] In this embodiment, the contact-type eliminator 101 may also use a predetermined eliminator bias voltage Vd1, but since the physical properties or charge of the medium S vary, it is preferable to control the eliminator bias voltage Vd1 according to the surface potential of the medium S.

[0171] In this example, such as Figure 13 As shown in (a), a surface potentiometer 190 can be installed at any point between the conveyor rollers 94 to measure the surface potential of the medium S in a non-contact manner. Here, the surface potentiometer 190 can be, for example, an ESV (electrostatic voltmeter) that utilizes electrostatic measurement. In this example, as... Figure 13 As shown in (a) and (b), a surface potentiometer 190 is positioned at a location corresponding to the center line CL in the width direction intersecting the transport direction of the medium S (equivalent to half the width dimension w of the medium S). A grounded counter electrode 191 is provided at a location opposite the surface potentiometer 190, so that the medium S contacts and passes through the counter electrode 191. Furthermore, in Figure 13 In (a), reference numeral 192 refers to the support bracket of the surface potentiometer 190. Furthermore, the measured value of the surface potentiometer 190 can be, for example, the average of the results measured over a specified time, or the average of the results measured at multiple locations. Alternatively, other calculation methods can be used for measurement.

[0172] Figure 14 This is a flowchart for implementing the voltage bias control of a contact-type eliminator.

[0173] In this figure, it is checked whether the de-energizing condition is that of the contact-type energizer 101 is used. When the contact-type energizer 101 is used, the physical property information of the medium S is read, and then the surface potential of the medium S is measured by the surface potentiometer 190.

[0174] Then, determine the de-energizing bias voltage Vd1 and apply it to the de-energizing roller 111.

[0175] <Layout of Surface Potentiometer>

[0176] Regarding the layout of the surface potentiometer 190, it can be positioned upstream of the contact-type eliminator 101 in the transport direction of the medium S, or it can be positioned downstream. Here, in the arrangement where the surface potentiometer 190 is positioned upstream of the contact-type eliminator 101 in the transport direction of the medium S, the de-energizing bias voltage Vd1 of the contact-type eliminator 101 can be controlled by feedback from the first medium S.

[0177] In contrast, in the configuration where a surface potentiometer 190 is installed downstream of the contact-type eliminator 101 in the transport direction of the medium S, after measuring the surface potential of the first medium S for testing, feedback control of the de-energizing bias voltage Vd1 of the contact-type eliminator 101 can be performed for the second and subsequent mediums S. However, since the surface potential on the medium S after de-energization by the contact-type eliminator 101 is being measured, a large potential does not need to be measured, and consequently, the surface potentiometer 190 needs to be miniaturized.

[0178] Furthermore, in this example, the measurement results of the surface potentiometer 190 are not used to control the excitation bias voltage Vd2 of the non-contact exciter 102. This is because the excitation potential level of the non-contact exciter 102 is lower than that of the contact exciter 101, so it is not necessary to control the excitation bias voltage Vd2 of the non-contact exciter 102.

[0179] <Method for determining the bias voltage Vd1>

[0180] The method for determining the excitation bias voltage Vd1 using the contact-type excitation device 101 can be appropriately selected, but in this example, it is preferable that the dielectric S is excitationd in such a way that the distribution of positive and negative charges on the surface after excitation is more uniform compared to before excitation, thereby selecting the excitation bias voltage Vd1. In particular, in this example, the dielectric S is preferably excitationd in such a way that the distribution of surface charge after excitation is such that the proportion of the charge that was dominant before excitation is greater.

[0181] Now, as Figure 15 As shown in (a), it is assumed that the surface potential of the dielectric S before de-energization is Vc1, and the negative charge dominates before de-energization.

[0182] At this time, Vd1 is used as the de-energizing bias voltage of the contact-type de-energizer 101. Let the surface potential of the de-energized medium S be Vc2. Let |Vc2| decay to a value close to 0. Vd1 can be selected in such a way that Vc2 and Vc1 have the same polarity.

[0183] Thus, after selecting the current-biased voltage Vd1, as follows: Figure 15As shown in (b), before de-electrode charging, the charge distribution of the dielectric S is dominated by negative charges (represented by white circles in the figure) and uniformly distributed compared to positive charges (marked by white circles with an × in the figure), and the surface potential is Vc1. In contrast, after de-electrode charging, the charge distribution of the dielectric S is unevenly distributed with negative charges in a manner where the proportion of negative charges is greater, and de-electrode charging occurs with a surface potential decrease to Vc2, at a rate of |ΔVc1|. Furthermore, regarding the charge distribution of the dielectric S after de-electrode charging, the dashed white circles represent regions of decaying negative charges, and the dashed white circles with an × indicate regions of positive charges.

[0184] The reasons for selecting such a power removal mode are as follows: for example, when the proportion of positive charges that are different from the dominant negative charges in the medium S before power removal is large, the power removal bias voltage Vd1 is too strong, so Vc2 is not a value close to 0, thus avoiding a potential with the opposite polarity to the potential before power removal.

[0185] <Selection of the initial value of the de-energizing bias voltage for contact-type eliminators>

[0186] As mentioned earlier, when controlling the de-energizing bias voltage Vd1 of the contact-type energizer 101, it is preferable to select an initial value of the de-energizing bias voltage Vd1 that is optimal for the surface potential of the medium S. However, in order to select the initial value of the de-energizing bias voltage Vd1, it is necessary to apply multiple candidate de-energizing bias voltages Vd1 to the test medium S in a predetermined charged state, and to measure the degree of attenuation of the surface potential of the medium S caused by each de-energizing bias voltage Vd1 using a surface potentiometer 190.

[0187] Therefore, in this example, as Figure 16 As shown in (a), the surface potentiometer 190 needs to be positioned downstream of the contact-type eliminator 101 in the direction of medium S transport (equivalent to the position shown by the double-dotted line in the figure).

[0188] In this example, such as Figure 16 As shown in (b), after applying different de-energizing bias voltages Vd1 (specifically, Vd1(1) to Vd1(3)) to the test medium S at three locations, such as blocks PT1 to PT3 (all with the same surface potential under the same charging conditions), the surface potential remaining on the medium S is measured. For example, the surface potential remaining on the medium S is set as Vc2 (specifically, Vc2(1) to Vc2(3)) for each de-energizing condition, and this is described as follows: Figure 16 As shown by the measurement line in (c), it can be understood that as the bias voltage Vd1 increases, the surface potential Vc2 remaining on the dielectric S decreases. At this point, according to... Figure 16The linear metering line of (c) approximates the residual surface potential Vc2 to approximately 0 when the voltage-removing bias Vd1 (specifically, Vd1(0)) is reached.

[0189] Thus, for a predetermined surface potential Vc1 of the medium S, the optimal de-energizing bias Vd1 (Vd1(0)) for de-energizing is calculated. This allows for the selection of the optimal de-energizing bias Vd1 based on its initial value for de-energizing any charged surface potential Vc1. However, it is not necessary to approximate a straight line based on the metering line; any method can be used to determine the initial value of the de-energizing bias Vd1 based on the multiple surface potentials remaining on the medium S after applying different de-energizing bias Vd1.

[0190] -About the electrostatic removal parameters of non-contact electrostatic precipitators-

[0191] In this example, such as Figure 17 As shown in (a), the non-contact eliminator 102 is connected to an eliminator power supply 125, which applies an eliminator bias voltage Vd2 consisting of an AC voltage component with overlapping DC voltage components between the discharge wire 122 and the eliminator housing 121.

[0192] In this example, a de-energizing bias voltage Vd2, containing an AC voltage component, is applied between the discharge wire 122 and the de-energizing housing 121, thus generating positive (+) and negative (-) ions due to corona discharge from the vicinity of the discharge wire 122. In this example, positive (+) and negative (-) ions are generated alternately at half-cycles of the frequency f (Hz) of the de-energizing bias voltage Vd2.

[0193] Here, we study the removal parameters of the non-contact eliminator 102. As the frequency f of the removal bias voltage Vd2 increases, the generation cycle of positive ions (+) and negative ions (-) becomes faster, thus suggesting an increase in the amount of ions generated.

[0194] Furthermore, considering the transport speed v of medium S, if the ion generation cycle remains unchanged (the ion frequency remains unchanged) when the transport speed v of medium S is relatively fast, the ion balance will deteriorate.

[0195] In this example, considering this, focusing on the current removal parameter f / v, which uses the conveying speed v of the medium S and the frequency f of the current removal bias voltage Vd2 containing the AC voltage component, it is determined that when selecting the optimal range of the current removal parameter f / v based on the evaluation method of using the medium S as described later, the following formula is preferably satisfied.

[0196] f / v≥0.8……(Equation 1)

[0197] In Equation 1, it is particularly preferred to satisfy the following equation.

[0198] f / v≥1.5……(Equation 2)

[0199] Furthermore, in this example, such as Figure 17 As shown in (a), the opening 128 of the non-electric housing 121 is formed to have a width L in the transport direction of the medium S.

[0200] Here, the opening width L of the opening 128 of the non-electrostatic housing 121 restricts the ion emission region toward the medium S. If the opening width L is narrow, the ion emission region becomes narrower; conversely, if it is wider, the ion emission region becomes wider. Therefore, the amount of ions per unit length can be adjusted by the relationship between the amount of ions and the ion emission region. Specifically, if the opening width L is long, there is a concern that the ion balance in the entire region of the opening 128 may deteriorate if the ion generation cycle (ion frequency) is not shortened.

[0201] Thus, it is inferred that the opening width L of the electrostatic removal housing 121 affects the electrostatic removal effect.

[0202] Considering this, it is determined that when selecting f / v*L as the electrostatic removal parameter, the following formula is preferably satisfied.

[0203] f / v*L≥30……(Equation 3)

[0204] Furthermore, the reasons for adopting Formulas 1 to 3 will be described in detail through Example 4, which will be described later.

[0205] Furthermore, in this example, it is evident that if the opening width L is narrow, insufficient de-energization may occur if the frequency is not at a higher than specified level. This can be presumed to be because the narrower ion emission region results in a reduced amount of ions received per unit length of the medium S passing through the non-contact energizer 102. On the other hand, if the opening width L is larger, the ion emission region becomes wider, thus increasing the amount of ions received per unit length of the medium S passing through the non-contact energizer 102. Therefore, compared to the case with a narrower opening width L, sufficient de-energization can be achieved even at a lower frequency.

[0206] -Utilizing the corona discharge characteristics of non-contact eliminators-

[0207] In this example, such as Figure 17 As shown in (a), the bias voltage Vd2 applied to the discharge wire 122 is an AC voltage component Vac (with peak-to-peak voltage Vpp and frequency f) that overlaps the DC voltage component Vdc (in this example, a positive voltage). At this time, a corona discharge is generated around the discharge wire 122. Figure 17 (b) shows the voltage-current characteristics of corona discharge.

[0208] exist Figure 17In (b), the horizontal axis represents the applied voltage and the vertical axis represents the corona discharge current. The absolute value of the applied voltage generated by negative corona (equivalent to negative ions (-)) is lower than that generated by positive corona (positive ions (+)).

[0209] Here, in this example, the AC voltage component Vac is superimposed on the DC voltage component Vdc in the bias voltage Vd2, thus as follows: Figure 17 As shown in (c), from the solid line to the thin line, it illustrates the change of the AC voltage component Vac toward the + side as the DC voltage component Vdc.

[0210] At this point, for example, assuming Vpp is ±4kV, Vdc is +0.3kV, the positive corona discharge initiation voltage is +2kV, and the negative corona discharge voltage is -1.7kV, Figure 17 The slanted region in (c) represents the ion-generating region. Positive corona (positive ions (+)) is generated in the ion-generating region above +2kV, while negative corona (negative ions (-)) is generated in the ion-generating region below -1.7kV. Therefore, compared to the case where the DC voltage component Vdc is not overlapped, the generation of positive and negative ions is more evenly balanced.

[0211] -Regarding the static eliminator function of non-contact static eliminators-

[0212] In this example, as shown in Figure 18(a), the non-contact eliminator 102 is grounded with a ground electrode 123 as the opposing electrode, positioned opposite the discharge wire 122. By providing such a ground electrode 123, positive ions (+) generated around the discharge wire 122 are drawn towards the ground electrode 123 to remove the surface charge (mainly negative charge e-) of the medium S.

[0213] In contrast, such as Figure 18 As shown in (b), in the case where the ground electrode 123 is not disposed opposite to the discharge wire 122 as the opposing electrode, the ions generated around the discharge wire 122 are not actively pulled toward the surface charge (mainly negative charge e-) side of the medium S for de-energization only by radiating them around the discharge wire 122.

[0214] Comparison of AC bias voltage and DC bias voltage -

[0215] In this example, power supply 125 is used for power removal, such as Figure 18 As shown in (c), the de-energizing bias Vd2 is an AC de-energizing bias composed of overlapping DC voltage components. On the surface of dielectric S, positive ions (+) and negative ions (-) mix to provide de-energizing. Therefore, both the negative charge e- and the positive charge e+ on the surface of dielectric S are de-energized, resulting in the surface potential of dielectric S decaying approximately toward 0.

[0216] In contrast, as a power supply for power removal 125', such as Figure 18 As shown in (d), assuming that the de-biasing voltage Vd2 is a DC de-biasing voltage consisting only of DC voltage components, only positive ions (+) are generated around the discharge wire 122. These positive ions (+) de-electrode the negative polarity charge e- on the surface of the dielectric S, but no negative ions (-) are generated to de-electrode the positive polarity charge e+ in the surface charge of the dielectric S. Thus, the positive polarity charge e+ on the dielectric S is not removed.

[0217] Thus, in this example, by using an AC bias voltage to remove charge, even if the surface charge of the dielectric S is a mixture of positive charge e+ and negative charge e-, it is possible to remove charge from both.

[0218] -Non-contact eliminator bias control-

[0219] In this example, the non-contact eliminator 102 can use fixed eliminator parameters, but in ways where the conveying speed v of the medium S changes, such as... Figure 19 As shown in (b), the frequency f of the non-electric bias voltage Vd2 is preferably controlled according to the conveying speed v of the medium S.

[0220] In other words, in this example, a speed sensor 200 is installed in the middle of the transport path of the medium S to detect the transport speed v of the medium S. The speed information from the speed sensor 200 is taken into the control device 131, which controls the frequency f of the bias voltage Vd2.

[0221] In this example, the control device 131 is equipped with a voltage-stripping control program for the non-contact eliminator 102, which executes... Figure 19 The bias control process shown in (a) is a voltage reduction control process.

[0222] exist Figure 19 In (a), the control device 131 checks whether the non-contact eliminator 102 is in operation and, if the non-contact eliminator 102 is in operation, reads the physical property information of the medium S and then measures the transport speed v of the medium S by the speed sensor 200.

[0223] Then, determine the frequency f of the de-biasing voltage Vd2, and apply the de-biasing voltage Vd2 to the discharge wire 122.

[0224] In this example, such as Figure 19 As shown in (b), for example, when the conveying speed v of medium S is faster than the normal speed, the frequency f can be f (large). Conversely, when the conveying speed v of medium S is slower than the normal speed, the frequency f can be f (small).

[0225] ◎Implementation Method 2

[0226] Figure 20 The overall structure of the image forming apparatus of Embodiment 2 is shown.

[0227] In this figure, the image forming apparatus 20 includes an image forming unit 210 with a built-in image forming section 22 and a de-energizing unit 220 that receives and de-energizes the medium S discharged from the outlet portion of the horizontal transport path 84 of the image forming unit 210. Unlike the image forming apparatus of Embodiment 1, the image forming unit 210 is equipped with all elements other than the de-energizing device 100 (image forming section 22, intermediate transfer body 30, fixing device 70, and media transport system 80), and the de-energizing device 100 is assembled in the de-energizing unit 220.

[0228] In addition, for the same constituent elements as in Embodiment 1, the same reference numerals are used as in Embodiment 1, and their detailed descriptions are omitted here.

[0229] In this example, such as Figure 20 and Figure 21 As shown, the static removal unit 220 has a horizontal transport path 221 for transporting the medium S discharged from the image forming unit 210 in a generally horizontal direction, and an appropriate number of transport rollers 222 to 224 are provided in the horizontal transport path 221. Furthermore, a medium discharge receiving part 86 is provided at the outlet of the horizontal transport path 221. In addition, a contact-type static remover 101 is provided as a static removal device 100 in the area between the transport rollers 222 and 223 in the horizontal transport path 221, and a non-contact-type static remover 102 is provided downstream of the contact-type static remover 101 in the transport direction of the medium S.

[0230] In this example, a control device 240 is also assembled in the current removal unit 220. For example, a surface potentiometer 190 for measuring the surface potential of the medium S is provided in the area between the conveyor rollers 223 and 224, and a speed sensor 200 is provided in the area between the conveyor roller 222 and the contact-type current collector 101 in the horizontal conveying path 221.

[0231] In addition, the basic structure of the contact-type eliminator 101 is roughly the same as that of embodiment 1, but the eliminator power supply 115 has a positive DC power supply 115a and a negative DC power supply 115b arranged in parallel, so that they can be switched by the switching switch 250.

[0232] Then, the control device 240 switches between the positive DC power supply 115a and the negative DC power supply 115b of the power removal power supply 115 via the switching switch 250, depending on whether the medium S of the medium reversal mechanism 89 in the image forming unit 210 is reversed.

[0233] In addition, similar to Embodiment 1, the control device 240 implements the de-energizing bias control of the contact-type energizer 101 (control corresponding to the surface potential of the medium S) and the de-energizing bias control of the non-contact-type energizer 102.

[0234] In this example, the power removal device 100 is located downstream of the medium reversal mechanism 89 in the image forming unit 210 in the transport direction of the medium S, thereby switching between the positive DC power supply 115a and the negative DC power supply 115b of the power removal power supply 115 depending on whether the medium S is reversed.

[0235] For example, Figure 22 As shown in (a), when the dielectric S does not enter the de-energizing unit 220 via the dielectric reversal mechanism 89, the control device 240 switches to select the positive DC power supply 115a as the de-energizing power supply 115. Therefore, the surface charge of the dielectric S is properly de-energized by the de-energizing bias voltage Vd1 generated by the de-energizing power supply 115 (using the positive DC power supply 115a).

[0236] On the other hand, such as Figure 22 As shown in (b), when the dielectric S enters the de-energizing unit 220 in a state where it is reversed via the dielectric reversing mechanism 89, the control device 240 switches to select the negative polarity DC power supply 115b as the de-energizing power supply 115. Therefore, the surface charge of the dielectric S is appropriately de-energized by the de-energizing bias voltage Vd1 generated by the de-energizing power supply 115 (using the negative polarity DC power supply 115b).

[0237] In addition, in this example, the polarity of the power supply 115 for power removal is switched according to the reversal of the medium S, but it is not limited to this. For example, when the medium S is reversed by the medium reversal mechanism 89, power removal using the power removal device 100 can be omitted. In addition, when the medium S is reversed by the medium reversal mechanism 89, it can also be set so that power removal processing using the power removal device 100 cannot be selected on the UI (User Interface).

[0238] ◎Deformation Method 1

[0239] Figure 23 (a) shows a variation of the non-contact eliminator 102.

[0240] In this figure, the basic structure of the non-contact eliminator 102 is as follows: the eliminator housing 121 is divided into two chambers by the partition 260, and discharge wires 122 (122a and 122b in this example) are installed in each chamber. An eliminator bias voltage Vd2 containing an AC voltage component is applied to each discharge wire 122 from the eliminator power supply 125 (which includes an AC power supply 126 and a DC power supply 127).

[0241] Furthermore, in this example, such as Figure 23 As shown in (a) and (b), a plate-shaped shielding member 270 is provided to block the opening 128 of the power-dissipating housing 121, and the shielding member 270 has a through hole 271.

[0242] In particular, in this example, two discharge wires 122 (122a, 122b) extend in a width direction intersecting the transport direction of the medium S, but as... Figure 23 As shown in (b) and (c), the through-hole 271 of the shielding member 270 intersects with the plurality of discharge wires 122a and 122b in an inclined direction, and is arranged at predetermined intervals along the length direction of the plurality of discharge wires 122a and 122b. Here, the through-hole 271 may also extend continuously across two discharge wires 122a and 122b, but in this example, the dividing portion 272 that divides the through-hole 271 into two parts is integrally formed on the shielding member 270 corresponding to the dividing member 260.

[0243] Therefore, in this embodiment, at least any one of the plurality of discharge wires 122a, 122b is exposed in any region along its length. For example, in Figure 23 In (c), for example, one discharge wire 122a is shielded by the shielding member 270 at any part of its length (e.g., region α), while another discharge wire 122b is exposed at any part of its length (e.g., region α) facing the through-hole 271 of the shielding member 270. Furthermore, multiple discharge wires 122a and 122b are arranged such that one discharge wire 122a is exposed at any part of its length (e.g., region β) facing the through-hole 271, while another discharge wire 122b is shielded by the shielding member 270 at any part of its length (e.g., region β).

[0244] Thus, in this example, at least any one of the multiple discharge wires 122a, 122b is exposed in any region along the length direction, so there is no need to worry about the de-energization process between the discharge wire 122 and the dielectric S being cut off midway through the discharge wires 122a, 122b.

[0245] Furthermore, in this example, the shielding member 270 is made of an insulating material, which is preferable in that the ions generated by the discharge wires 122a and 122b will not unnecessarily leak on the shielding member 270 side. As a material for the shielding member 270, a resin such as polycarbonate can be used, for example.

[0246] ◎Deformation Method 2

[0247] Figure 24 (a) shows the non-contact type eliminator 102 in variant mode 2.

[0248] In this figure, the non-contact eliminator 102 uses a needle electrode 300 instead of the discharge wire 122, which is a linear electrode, used in embodiments 1, 2 and modified 1.

[0249] In this example, such as Figure 24 As shown in (a) and (b), the needle-shaped electrode 300 is arranged at predetermined intervals relative to the conductive support member 301 extending along the width direction of the medium S. A de-energizing bias voltage Vd2 from the de-energizing power supply 125 (which includes an AC power supply 126 and a DC power supply 127) is applied to the support member 301, causing positive ions (+) and negative ions (-) to be generated around the needle-shaped electrode 300. A ground electrode 310 is provided on the medium S side as a counter electrode opposite to the needle-shaped electrode 300. The positive and negative ions generated around the needle-shaped electrode 300 are pulled toward the surface charge portion of the medium S, thereby de-energizing the surface charge of the medium S.

[0250] Furthermore, the number of needle electrodes 300 can be appropriately selected in a manner that enables current removal operation across the entire width direction of the dielectric S. Additionally, as... Figure 24 As shown in (c), a shielding member 270 may also be provided between the needle electrode 300 and the dielectric S, and a through hole 271 may be opened only at the location corresponding to the needle electrode 300, thereby preventing the dielectric S from contacting the needle electrode 300 and ensuring the discharge operation of the needle electrode 300.

[0251]

Example

[0252] ◎Example 1

[0253] Example 1 uses the current removal device 100 (contact type current removal device 101 and non-contact type current removal device 102) of Embodiment 1 to visualize and evaluate the current removal state using the contact type current removal device 101 and the non-contact type current removal device 102.

[0254] Figure 25 (a) shows an example of spraying a negatively charged toner (M: magenta toner) and a positively charged toner (C: cyan toner) onto a medium S and visualizing the charge distribution (electrostatic pattern) on the medium S.

[0255] In this figure, label 330 is the spray chamber for the toner. A grounded metal plate 331 is placed inside the spray chamber 330. A medium S, such as a resin film, is placed on the metal plate 331. Air is sprayed towards the toner in the grid container 332 located inside the spray chamber 330, thereby creating a cloud-like state of toner within the spray chamber 300. In this way, the clouded toner is drawn to the surface charge of the medium S, thus adhering to the toner and making it visible.

[0256] Figure 25 (b) shows, from left to right, the following scenarios: visualization of the medium S before de-energization; visualization of the medium S after de-energization using contact-type energizer 101 (after de-energization using 2Roll); visualization of the medium S after de-energization using contact-type energizer 101 and non-contact energizer 102 (de-energization using gridless electrode type, electrode gap 3mm); visualization of the medium S after de-energization using contact-type energizer 101 and non-contact energizer 102 (de-energization using gridless electrode type, electrode gap 0mm).

[0257] according to Figure 25 (b) confirms that before de-electrification, the negative charge was uniformly present on the surface of the medium S. After de-electrification using the contact-type de-electrifier 101, most of the negative charge was de-electrified, but the negative charge remained as a non-uniform mass compared to before de-electrification, and positive charge was generated in a smaller area compared to the negative charge. In contrast, it should be understood that after de-electrification using the non-contact-type de-electrifier 102, the surface charge of the medium S was essentially de-electrified.

[0258] ◎Example 2

[0259] Figure 26 (a) shows the relationship between the applied voltage and the potential after energization when the contact-type energizer 101 is under constant voltage control.

[0260] Figure 26 (b) shows the relationship between the applied current value and the potential after energization when the contact-type energizer 101 is under constant current control.

[0261] The experimental conditions are as follows.

[0262] • Environment: 22 degrees Celsius, 55% humidity

[0263] • Medium: PET film, 100μm, A3 size

[0264] • Media delivery speed: 546 mm / sec.

[0265] Secondary transfer voltage: -3kV

[0266] • Electrostatic eliminator roller on the front side of the medium: ASKERC 65 degrees, diameter 20mm, volume resistivity 10 6.5 Ω·cm

[0267] • Electrostatic eliminator roller on the back side of the medium: ASKERC 75 degrees, diameter 24mm, volume resistivity 10 7 Ω·cm

[0268] exist Figure 26In the constant voltage control of (a), the discharge stops when the voltage drops below the discharge start voltage. Therefore, regardless of the input surface potential, the surface potential after discharge converges to a certain range.

[0269] In contrast, Figure 26 In the constant current control of (b), even if the roller resistance changes due to temperature rise or time, the current value remains unchanged. Therefore, the system resistance fluctuates more strongly, but a certain amount of charge is provided to the medium S, so the surface potential after de-energization may be scattered due to the input surface potential.

[0270] ◎Example 3

[0271] Figure 27 The figure is obtained by investigating the effect of the meshing variation of the dual-structure eliminator rollers 111 and 112 of the contact-type eliminator 101.

[0272] The experimental conditions are as follows:

[0273] • Media delivery speed: 182 mm / sec.

[0274] Constant pressure control

[0275] • Excluding bias voltage: 1500V

[0276] • Electrostatic eliminator roller on the front side of the medium: ASKERC 70 degrees, diameter 20mm, volume resistivity 10 6 Ω·cm

[0277] • Electrostatic eliminator roller on the back side of the medium: ASKERC 75 degrees, diameter 24mm, volume resistivity 10 7 Ω·cm

[0278] exist Figure 27 In the context of the term "In-side intrusion amount", the intrusion amount refers to the amount of intrusion from the center of the metal shaft located near the front side of the electric stripper roller to the opposite side of the electric stripper roller. The intrusion amount refers to the amount of intrusion from the center of the metal shaft located inside the electric stripper roller to the opposite side of the electric stripper roller.

[0279] exist Figure 27 In the diagram, ○ indicates that the medium's transportability, engagement, and de-energizing properties (Δ potential: possible de-energizing potential) are good, while × indicates that all are NG (bad).

[0280] Here, the difference in the amount of intrusion on the In and Out sides of the electrostatic removal roller refers to the fact that the dual-structure electrostatic removal roller is configured with an axial inclination, and it is confirmed that by using an elastomer in the electrostatic removal roller, there is a range of good conveying, engagement, and electrostatic removal performance for the medium.

[0281] ◎Example 4

[0282] Figure 28(a) In the non-contact eliminator, the medium conveying speed v, the frequency f of the eliminator bias voltage Vd2, the value of the eliminator parameter f / v, and the evaluation results of medium adhesion are shown respectively. In addition, in the evaluation results, "○-" indicates a good eliminator result, "○" indicates a better eliminator result than "○-", and "×" indicates an insufficient eliminator result.

[0283] Figure 28 (b) is an explanatory graph showing the relationship between frequency, which is the power removal parameter, and other parameters when good power removal results are obtained. Figure 28 (c) is an explanatory graph showing the relationship between the removal parameter f / v and other parameters when good removal results are obtained. Figure 28 (d) is an explanatory diagram showing the relationship between the current removal parameter f / v*L (where L is the opening width of the current removal housing) and other parameters when good current removal results are obtained.

[0284] In this example, Figure 29 (a) shows an example of a method for evaluating the adhesion of a medium.

[0285] In this figure, five media S made of resin film are stacked. The bottom four are fixed to the metal plate 401. After being placed for 24 hours after being de-energized, the clamp 402 is installed on the top medium S, and the degree of adhesion of the medium S is measured. The measurement value is then used for evaluation.

[0286] Here, by observing the relationship between frequency and tensile load, we obtain... Figure 29 The result shown in (b) is as follows.

[0287] Using media A (OZK100, manufactured by Heiwa Paper) and media B (OZK188, manufactured by Heiwa Paper) instead of the un-electrostatic condition, with frequencies f of 100Hz and 800Hz, the adhesion evaluation of the media was performed under the electrified condition. Measurements could not be taken under the un-electrostatic condition, but when electrification was performed at an appropriately selected frequency, the adhesion evaluation of both media A and B was below the target tensile load, which was satisfactory. Furthermore, the target tensile load was set at 1.4N because it was confirmed that if the target level is below, the media can be easily conveyed to the post-processing device via the usual media conveying rollers after being laminated on the media discharge receiving section 86.

[0288] according to Figure 28 (a) to (d) should be understood as good.

[0289] f / v≥0.8……(Equation 1)

[0290] f / v≥1.5……(Equation 2)

[0291] f / v*L≥30……(Equation 3)

[0292] ◎Example 5

[0293] Figure 30 (a) is an explanatory diagram showing the de-energizing effect of a medium when using a non-contact de-energizer and the de-energizing parameter f / v is above a specified value.

[0294] Figure 30 (b) is an explanatory diagram showing the de-energizing effect of the medium when using a non-contact de-energizer and the de-energizing parameter f / v is less than a specified value.

[0295] In all cases, the charged state of the medium is visualized using the method employed in Example 1.

[0296] according to Figure 30 (b) It should be understood that when the charge removal parameter f / v is less than the specified value, a residual charge remains in each ion generation cycle. Conversely, it should be understood that if the charge removal parameter f / v is above the specified value, the residual charge is almost not left on the medium and has been removed.

[0297] ◎Example 6

[0298] Figure 31 The removal effect of electrode distance (the distance between the discharge wire and the medium) in non-contact eliminators was verified.

[0299] exist Figure 31 The image shows the de-energized state of the medium after passing through a contact-type energizer following 2-Roll de-energization, with a significant amount of charge remaining on each medium sheet.

[0300] Then, when performing static electricity removal using a non-contact static electricity remover by varying the electrode distance, it should be understood that the static electricity removal effect is good when the electrode distance is within 3mm. However, in the example with an electrode distance of 9mm, it should be noted that if the distance between the discharge wire and the dielectric is too wide, the static electricity removal effect of the non-contact static electricity remover will be insufficient.

Claims

1. A device for removing electric charges, wherein, The device for removing electricity comprises: a discharge electrode disposed in a non-contact state with a medium and removing electricity from the medium; a measurement circuit that measures a surface resistance of the medium; and a power source that applies a discharge voltage including an alternating component at least including an overlapping direct current voltage component to the discharge electrode, wherein, when a conveying speed of the medium is v [mm / sec.] and a frequency of the discharge voltage is f [Hz], the following equation is satisfied: f / v ≥ 0.8... (Equation 1), the device for removing electricity further comprises a control unit that controls the frequency of the discharge voltage according to the conveying speed of the medium, the control unit controls on / off of the power source according to the measured surface resistance of the medium, the discharge electrode is shielded from the medium by a shielding member having a through-hole through which all or a part of the discharge electrode is exposed, the discharge electrode has a plurality of linear electrodes extending in a cross direction intersecting a conveying direction of the medium, the through-hole intersects the plurality of linear electrodes in an inclined direction and is provided at a predetermined interval, and each of the through-holes has two edges in a length direction of the linear electrodes.

2. The device for removing electricity according to claim 1, wherein the device for removing electricity satisfies the following equation: f / v ≥ 1.5... (Equation 2).

3. The device for removing electricity according to claim 1 or 2, wherein the discharge electrode is covered by a housing having an opening portion in a region opposite to the medium, wherein, when an opening width in a conveying direction of the medium in the opening portion of the housing is L [mm], the following equation is satisfied: f / v*L ≥ 30... (Equation 3).

4. The device for removing electricity according to claim 1, wherein the plurality of linear electrodes are shielded from the medium by the shielding member, and the through-hole exposes at least any linear electrode of the plurality of linear electrodes in any region in a length direction.

5. The device for removing electricity according to claim 1, wherein the shielding member is composed of an insulating material.

6. A device for removing an electric charge, wherein The device for removing electricity comprises: a non-contact type electricity removing unit having a discharge electrode disposed in a non-contact state with a medium and removing electricity from the medium, a measurement circuit that measures a surface resistance of the medium, and a power source that applies a discharge voltage including an alternating component at least including an overlapping direct current voltage component to the discharge electrode, wherein, when a conveying speed of the medium is v [mm / sec.] and a frequency of the discharge voltage is f [Hz], the following equation is satisfied: f / v ≥ 0.8... (Equation 1); and a contact type electricity removing unit provided at a position on an upstream side in a conveying direction of the medium than the non-contact type electricity removing unit and having an electricity removing member in contact with the conveyed medium, and removing electricity from the medium by applying a voltage to the electricity removing member, the device for removing electricity further comprises a control unit that controls the frequency of the discharge voltage according to the conveying speed of the medium, the control unit controls on / off of the power source according to the measured surface resistance of the medium, the discharge electrode is shielded from the medium by a shielding member having a through-hole through which all or a part of the discharge electrode is exposed, the discharge electrode has a plurality of linear electrodes extending in a cross direction intersecting a conveying direction of the medium, the through-hole intersects the plurality of linear electrodes in an inclined direction and is provided at a predetermined interval, and each of the through-holes has two edges in a length direction of the linear electrodes. The discharge electrode has a plurality of linear electrodes extending in a cross direction intersecting a conveying direction of the medium, The through holes intersect the plurality of linear electrodes in an oblique direction and are arranged at a predetermined interval, each of the through holes having two edges in a length direction of the linear electrodes.

7. A media processing device, wherein, The medium processing apparatus includes: a conveying unit that conveys a medium; a charging unit that is provided midway through a conveying path of the medium and charges the medium; and The destaticizer according to any one of claims 1 to 6 is provided at a position downstream of the charging unit in the conveying direction of the medium and decharges the medium charged by the charging unit.

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