Electrostatic eliminator device and image formation device

Abstract

To suppress a gas including ozone, generated at the center part of a corona discharge electrode extending in a crossing direction crossing a conveyance direction of a recording medium, from being stagnant on a surface of the recording medium as compared with a case in which the gas including the ozone is discharged from both ends of the recording medium in the crossing direction.SOLUTION: An electrostatic eliminator device comprises: a corona discharge electrode which is opposed to a recording medium being conveyed, and extends in a crossing direction crossing the conveyance direction of the recording medium; an air current generation device which lets a gas, blown to the corona discharge electrode, flow toward the recording medium; and a suction duct which is arranged upstream or downstream from the corona discharge electrode in the conveyance direction, and extends in the crossing direction and sucks in the gas made to flow to the recording medium by the air current generation device.SELECTED DRAWING: Figure 8

Description

[Technical Field]

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

[0002] The static elimination device described in Patent Document 1 has a static elimination member that contacts the transported charged medium and has a contact-type static elimination means that eliminates the majority of the charge on the charged medium, and a non-contact static elimination means that is located downstream of the contact-type static elimination means in the transport direction of the charged medium and eliminates the remaining charge on the charged medium in a non-contact manner after it has been neutralized by the contact-type static elimination means. [Prior art documents] [Patent documents]

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

[0004] The object of the present disclosure is to prevent ozone-containing gas generated in the central portion of a corona discharge electrode extending in the intersecting direction from stagnating on the surface of the recording medium, compared to when ozone-containing gas is discharged only from both ends of the recording medium in the intersecting direction that intersects the conveying direction of the recording medium. [Means for solving the problem]

[0005] The static elimination device according to a first aspect of the present disclosure is characterized by comprising: a corona discharge electrode that faces a recording medium being transported and extends in a direction intersecting the transport direction of the recording medium; an airflow generating device that causes gas around the corona discharge electrode to flow toward the recording medium; and an intake duct that is arranged upstream or downstream of the corona discharge electrode in the transport direction, extends in the intersecting direction, and sucks in the gas that has been caused to flow toward the recording medium by the airflow generating device.

[0006] A static eliminator according to a second aspect of the present disclosure is characterized in that, in the static eliminator described in the first aspect, the suction duct is arranged downstream of the corona discharge electrode in the transport direction, and a suppression member is provided upstream of the corona discharge electrode in the transport direction, extending in the intersecting direction and suppressing gas flowing toward the recording medium from flowing upstream of the corona discharge electrode in the transport direction.

[0007] A static eliminator according to a third aspect of the present disclosure is the static eliminator according to the second aspect, characterized in that the suppression member includes a discharge duct that extends in the intersecting direction and discharges gas toward the recording medium upstream of the corona discharge electrode in the transport direction.

[0008] A static eliminator according to a fourth aspect of the present disclosure is the static eliminator according to the third aspect, characterized in that the airflow generating device discharges gas from the discharge duct.

[0009] A static eliminator according to a fifth aspect of the present disclosure is characterized in that, in the static eliminator described in the third or fourth aspect, the discharge duct and the suction duct extend in the intersecting direction and protrude toward the corona discharge electrode on both sides of the intersecting direction.

[0010] A static eliminator according to a sixth aspect of the present disclosure is characterized in that, in the static eliminator described in the first aspect, the corona discharge electrode comprises a box-shaped shield case that opens toward the recording medium and extends in the intersecting direction, and a discharge wire that is disposed inside the shield case and extends in the intersecting direction, and a through hole is formed in the bottom plate of the shield case through which gas passes by the gas flow generated by the airflow generating device.

[0011] A static eliminator according to a seventh aspect of the present disclosure is the static eliminator according to the sixth aspect, characterized in that the suction duct is arranged downstream of the corona discharge electrode in the transport direction, extends in the intersecting direction, and has a discharge duct that discharges gas toward the recording medium upstream of the corona discharge electrode in the transport direction by a gas flow generated by the airflow generating device, and the flow path area of ​​the discharge duct and the opening area of ​​the through hole are determined so that the speed of the gas discharged from the discharge duct upstream of the corona discharge electrode is faster than the speed of the gas flowing from the corona discharge electrode toward the recording medium.

[0012] An image forming apparatus according to an eighth aspect of the present disclosure is characterized by comprising: a conveying unit that conveys a recording medium; an image forming unit that forms an image on the recording medium conveyed by the conveying unit; and a static elimination device according to any one of the first to seventh aspects that eliminates static electricity from the charged recording medium that is conveyed while the image is being formed. [Effects of the Invention]

[0013] The static elimination device according to the first aspect of the present disclosure can prevent ozone-containing gas generated in the central portion of the corona discharge electrode extending in the intersecting direction from stagnating on the surface of the recording medium, compared to when ozone-containing gas is discharged only from both ends of the recording medium in the intersecting direction that intersects the conveying direction of the recording medium.

[0014] The static eliminator according to the second aspect of the present disclosure can suppress an increase in the transport resistance imposed on the recording medium, compared to when a gas flow occurs from the downstream side to the upstream side in the transport direction.

[0015] The static eliminator according to the third aspect of the present disclosure can prevent the recording medium being transported from coming into contact with the resin plate and being damaged, compared to when a resin plate is used to suppress the flow of gas upstream.

[0016] The static eliminator according to the fourth aspect of the present disclosure can reduce the number of parts compared to when separate airflow generating devices are used, by discharging gas from the discharge duct and flowing gas with a high ozone concentration around the corona discharge electrode toward the recording medium.

[0017] The static eliminator according to the fifth aspect of the present disclosure can suppress leakage of ozone in the intersecting direction compared to a case in which the corona discharge electrodes protrude toward the discharge duct and the suction duct on both sides of the intersecting direction.

[0018] The static eliminator according to the sixth aspect of the present disclosure has a simpler configuration in which gas with a high ozone concentration around the corona discharge electrode flows toward the recording medium, compared to when no through-holes are formed in the bottom plate of the shield case.

[0019] The static eliminator according to the seventh aspect of the present disclosure can prevent gas flowing from the corona discharge electrode to the recording medium from flowing upstream in the transport direction of the recording medium, compared to when the speed of gas discharged from the discharge duct toward the recording medium is slower than the speed of gas flowing from the corona discharge electrode toward the recording medium.

[0020] The image forming apparatus according to the eighth aspect of the present disclosure can prevent ozone-containing gas from stagnating inside the apparatus, compared to an apparatus equipped with a static elimination device that discharges ozone-containing gas only from both ends of the recording medium in a direction intersecting the conveying direction of the recording medium. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a schematic configuration diagram showing an image forming apparatus according to a first embodiment of the present disclosure. [Figure 2] 1 is a schematic configuration diagram illustrating a toner image forming unit of an image forming apparatus according to a first embodiment of the present disclosure. [Figure 3] FIG. 2 is a perspective view showing a chain gripper of the image forming apparatus according to the first embodiment of the present disclosure. [Figure 4]FIG. 2 is a perspective view showing a secondary transfer roll and the like of the transfer device according to the first embodiment of the present disclosure. [Figure 5] FIG. 2 is a perspective view showing a heating roll, a pressure roll, and the like of the image forming apparatus according to the first embodiment of the present disclosure. [Figure 6] FIG. 2 is a cross-sectional view showing a heating roll, a pressure roll, and the like of the image forming apparatus according to the embodiment of the present disclosure. [Figure 7] 1 is an overall perspective view showing a static eliminator according to a first embodiment of the present disclosure. [Figure 8] 1 is a cross-sectional view of a static eliminator according to a first embodiment of the present disclosure, taken along a plane perpendicular to the depth direction. [Figure 9] 2 is an enlarged perspective view showing a corotron provided in the static eliminator according to the first embodiment of the present disclosure. FIG. [Figure 10] 1 is a cross-sectional view of a static eliminator according to a first embodiment of the present disclosure, taken along a plane perpendicular to the up-down direction. [Figure 11] 3A and 3B are perspective views showing the discharge port of the discharge duct and the suction port of the suction duct in the static eliminator according to the first embodiment of the present disclosure. [Figure 12] FIG. 2 is a front view showing a static eliminator according to a comparative example to the first embodiment of the present disclosure. [Figure 13] FIG. 5 is a cross-sectional view of a static eliminator according to a second embodiment of the present disclosure, taken along a plane perpendicular to the depth direction. DETAILED DESCRIPTION OF THE INVENTION

[0022] First Embodiment An example of a static eliminator and an image forming apparatus according to a first embodiment of the present disclosure will be described with reference to Figures 1 to 12. Note that arrow H shown in each figure indicates the vertical direction, i.e., the up-down direction of the apparatus, arrow W is perpendicular to arrow H and is horizontal, i.e., the width direction of the apparatus, and arrow D is perpendicular to arrows H and W and is horizontal, i.e., the depth direction of the apparatus.

[0023] The image forming apparatus 10 according to this embodiment is an electrophotographic image forming apparatus that forms a toner image on a sheet member P as a recording medium. As shown in FIG. 1, the image forming apparatus 10 includes a storage unit 50, an image forming unit 12, and a control unit 18 that controls each unit.

[0024] (Storage section 50) As shown in FIG. 1, the storage section 50 includes a stacking section 78 on which sheet members P are stacked, and a delivery roll 58 that delivers the topmost sheet member P stacked on the stacking section 78 to the supply path 40.

[0025] (Image forming unit 12) 1, image forming unit 12 is disposed above storage unit 50. Image forming unit 12 includes a toner image forming unit 20 that forms a toner image, a transfer device 30 that transfers the toner image formed in toner image forming unit 20 onto sheet material P, a fixing device 100 that fixes the toner image onto sheet material P, and a static eliminator 150 that eliminates static electricity charged on sheet material P.

[0026] [Toner image forming unit 20] As shown in Fig. 1, a plurality of toner image forming units 20 are provided to form toner images for each color. The image forming unit 12 is provided with toner image forming units 20 for a total of four colors: yellow (Y), magenta (M), cyan (C), and black (K). Y, M, C, and K shown in Fig. 1 indicate components corresponding to the above colors.

[0027] The toner image forming units 20Y, 20M, 20C, and 20K are basically configured in the same manner except for the toners they use.

[0028] 1, toner image forming units 20Y, 20M, 20C, and 20K are arranged along the horizontal portion of transfer belt 31 provided in transfer device 30. In the following description, when there is no need to particularly distinguish between toner image forming units 20Y, 20M, 20C, and 20K, the alphabet at the end of the name will be omitted.

[0029] 2, the toner image forming unit 20 includes an image carrier 21 that rotates in the direction of arrow A01 in the figure, and a charger 22 that charges the image carrier 21. The toner image forming unit 20 further includes an exposure device 23 that exposes the image carrier 21 charged by the charger 22 to light to form an electrostatic latent image, and a developing device 24 that develops the electrostatic latent image with toner to form a toner image.

[0030] [Transfer device 30] As shown in FIG. 1, the transfer device 30 includes a transfer belt 31 as an intermediate transfer member, a plurality of rolls 32, a primary transfer roll 33, a transfer cylinder , and a scraping member .

[0031] Transfer belt 31 is endless and is wound around multiple rolls 32 so as to assume an inverted triangular shape. Toner image forming units 20Y, 20M, 20C, and 20K are aligned along the upper horizontal portion of transfer belt 31. Transfer belt 31 rotates in the direction of arrow B when at least one of the multiple rolls 32 is driven to rotate.

[0032] In the following description, among the multiple rolls 32, the roll 32 arranged so as to push out the inclined portion on one side in the width direction of the transfer belt 31 (left side in the drawing) will be referred to as roll 32a, and the roll 32 around which the portion on one side in the width direction of the transfer belt 31 is wound will be referred to as roll 32b. Furthermore, the roll 32 arranged upstream of roll 32a in the rotation direction of the transfer belt 31 will be referred to as roll 32c.

[0033] Roll 32b functions as a drive roll that is rotationally driven by a driving force applied from drive source 34. Roll 32c presses transfer belt 31 from the rear surface thereof and functions as a tension applying roll that applies tension to transfer belt 31.

[0034] The primary transfer roll 33 is disposed on the opposite side of the image carrier 21 of each color across the transfer belt 31. The primary transfer roll 33 transfers the toner image formed on the image carrier 21 to the transfer belt 31 at a primary transfer position T between the image carrier 21 and the primary transfer roll 33.

[0035] The transfer cylinder 36 is disposed on the opposite side of the transfer belt 31 from the roll 32a and is driven to rotate. The transfer cylinder 36 transfers the toner image transferred onto the transfer belt 31 onto the sheet material P at a secondary transfer position NT between the transfer belt 31 and the transfer cylinder 36.

[0036] The scraping member 38 is disposed between the roll 32 a and the roll 32 b in the rotation direction of the transfer belt 31 , and scrapes off any deposits adhering to the surface of the transfer belt 31 from the transfer belt 31 .

[0037] [Fixing device 100] As shown in FIG. 1, the fixing device 100 includes a chain gripper 66 and a main heating section 120 that comes into contact with the sheet member P to heat the toner image.

[0038] -Chain Gripper 66- The chain gripper 66 includes a pair of chains 72, a leading end holding portion 68 that holds the leading end of the sheet material P, and sprockets 71, 73, 82, 84, and 86.

[0039] The pair of chains 72 are arranged at a distance from each other in the depth direction, as shown in Fig. 3, and are formed endlessly. The pair of chains 72 are wound around a pair of sprockets 73 that are arranged on both axial ends of the transfer cylinder 36 and whose axial direction is the depth direction, as shown in Fig. 4.

[0040] The pair of chains 72 are wound around a pair of sprockets 71 (see FIG. 5) that are arranged on one and the other axial ends of a pressure cylinder 140 (described later) and whose axial direction is the depth direction. The pair of chains 72 are also wound around a pair of sprockets 82, a pair of sprockets 84, and a pair of sprockets 86 that are arranged at an interval in the depth direction.

[0041] In addition, as shown in FIG. 1, the sprockets 71 arranged on both ends of the pressure cylinder 140 are arranged on one side in the width direction (the left side in the figure) and above the sprockets 73 arranged on both ends of the transfer cylinder 36.

[0042] Additionally, when viewed from the depth direction, the pair of sprockets 82 are disposed below the sprocket 71. Furthermore, the pair of sprockets 86 are disposed below the sprockets 73 and 82, on one side of the width direction of the sprocket 73, and on the other side of the width direction of the sprocket 82. Additionally, the pair of sprockets 84 are disposed so as to lift the portion of the chain 72 between the sprockets 82 and 86 from below to above.

[0043] As shown in Figure 3, the tip holding portion 68 has an attachment member 75 extending in the depth direction and a gripper 76 attached to the attachment member 75, and both sides of the tip holding portion 68 in the depth direction are respectively attached to a pair of chains 72.

[0044] A plurality of tip holders 68 are provided and are arranged at predetermined intervals along the circumferential direction (circumferential direction) of the chain 72 (see FIG. 1).

[0045] A plurality of grippers 76 are provided and attached to the attachment member 75 at predetermined intervals along the depth direction. The grippers 76 have a function of holding the leading edge of the sheet material P. Specifically, the grippers 76 have claws 76a. The attachment member 75 is also formed with contact portions 75a (see FIG. 6) with which the claws 76a come into contact.

[0046] The gripper 76 is configured to hold the sheet material P by pinching the leading end of the sheet material P between the claw 76a and the contact portion 75a. Note that the gripper 76 has the claw 76a pressed against the contact portion 75a by a spring or the like, and the claw 76a is moved toward and away from the contact portion 75a by the action of a cam or the like, for example.

[0047] In this configuration, when a rotational force is transmitted to sprockets 71 and 73 out of the plurality of sprockets 71, 73, 82, 84, and 86 shown in FIG. 1, the pair of chains 72 rotates in the direction of arrow C in the figure.

[0048] Furthermore, when the leading edge holding portions 68 attached to the pair of chains 72 reach the sprockets 73, the grippers 76 of the leading edge holding portions 68 pinch the leading edge of the sheet material P conveyed along the supply path 40 to hold and receive the sheet material P. Then, the chains 72, which rotate in the direction of arrow C, convey the sheet material P held by the leading edge holding portions 68 toward the secondary transfer position NT. The rotating chains 72 further convey the sheet material P toward the main heating unit 120. Furthermore, when the leading edge of the sheet material P passes through the main heating unit 120, the leading edge holding portions 68 release their hold on the leading edge of the sheet material P, and the chain grippers 66 send the sheet material P to the discharge path 42. The sheet material P sent to the discharge path 42 is then discharged to the outside of the device main body 10a.

[0049] -Main heating section 120- 1, the main heating section 120 is disposed downstream of the secondary transfer position NT in the conveying direction of the sheet member P (hereinafter referred to as the "sheet conveying direction"). The main heating section 120 also includes a heating roll 130 that comes into contact with the conveyed sheet member P to heat the sheet member P, and a pressure cylinder 140 that presses the sheet member P against the heating roll 130.

[0050] In this configuration, the pressure cylinder 140 presses the sheet member P toward the heating roll 130. Furthermore, the pressure cylinder 140 rotates by receiving a rotational force from a driving member (not shown). The heating roll 130 then rotates in response to the rotation of the pressure cylinder 140. Furthermore, the heating roll 130 and the pressure cylinder 140 sandwich and transport the sheet member P onto which the toner image has been transferred, whereby the toner image is heated and fixed to the sheet member P.

[0051] [Static eliminator 150] 1, the static eliminator 150 is disposed in the discharge path 42 downstream of the fixing device 100 in the conveying direction of the sheet member P. Specifically, the discharge path 42 is provided with a pair of discharge rolls 44 aligned in the width direction, and the static eliminator 150 is disposed between the pair of discharge rolls 44. The discharge rolls 44 are an example of a conveying section. The static eliminator 150 will be described in detail later.

[0052] (Action of image forming device) In the image forming apparatus 10 shown in Fig. 1, a toner image is formed on a sheet member P as follows. First, the charger 22 for each color shown in Fig. 2 uniformly negatively charges the surface of the image carrier 21 for each color to a predetermined potential. Next, based on image data input from the outside, the exposure device 23 irradiates the charged surface of the image carrier 21 for each color with exposure light to form an electrostatic latent image.

[0053] As a result, electrostatic latent images corresponding to the image data are formed on the surfaces of the image carriers 21. The developing devices 24 for each color then develop these electrostatic latent images into visible toner images. Furthermore, the primary transfer rolls 33 of the transfer device 30 shown in FIG. 1 transfer the toner images formed on the surfaces of the image carriers 21 for each color onto the transfer belt 31 at the primary transfer position T.

[0054] Therefore, the sheet material P sent out from the storage section 50 to the supply path 40 by the delivery roll 58 is handed over to the tip holding section 68 (see FIG. 3) of the chain gripper 66 and conveyed. The sheet material P conveyed by the chain gripper 66 is sent out toward the secondary transfer position NT. At the secondary transfer position NT, the sheet material P is sandwiched between the transfer belt 31 and the transfer cylinder 36 and conveyed, so that the toner image on the surface of the transfer belt 31 is transferred to the surface of the sheet material P.

[0055] Furthermore, the fixing device 100 fixes the toner image transferred onto the surface of the sheet material P onto the sheet material P, and the sheet material P transported by the chain gripper 66 is sent out to the discharge path 42. The sheet material P sent out to the discharge path 42 is discharged to the outside of the apparatus main body 10a.

[0056] (Main part configuration) Next, the static eliminator 150 will be described. 1 and 7, the static eliminator 150 is disposed on the opposite side of the discharge path 42 from the paper guide 46 provided along the discharge path 42 through which the sheet material P is discharged. Specifically, the paper guide 46 is disposed below the discharge path 42, and the static eliminator 150 is disposed above the discharge path 42.

[0057] The static eliminator 150 is shaped like a rectangular parallelepiped extending in the depth direction, and as shown in Figure 8, it is equipped with a corotron 160 that eliminates static electricity from the charged sheet member P by corona discharge, and a collection unit 170 that collects ozone generated by the corona discharge.

[0058] [Colotron 160] As shown in Fig. 8, corotron 160 includes a shield case 162, which is a housing, and a discharge wire 164, which is a discharge electrode to which a voltage is applied. Shield case 162 is made of stainless steel, is box-shaped, and is open on the discharge path 42 side, extending in the depth direction. Furthermore, a plurality of circular through holes 166 are formed in a bottom plate 162a of box-shaped shield case 162, arranged vertically and horizontally, as shown in Fig. 9. Corotron 160 is an example of a corona discharge electrode.

[0059] The discharge wire 164 is made of a metal wire such as tungsten, and is disposed inside the shield case 102, extending in the depth direction. Both ends of the discharge wire 164 are attached to a pair of side walls (not shown) of the shield case 162, each of which has a wall surface facing in the depth direction.

[0060] In this configuration, a voltage is applied to the discharge wire 164 from a power source (not shown) to generate a corona discharge, thereby eliminating static electricity from the charged sheet member P. Note that the corona discharge also generates ozone.

[0061] [Collection section 170] As shown in FIGS. 8 and 10, the recovery section 170 is provided so as to cover the corotron 160 from both sides in the width direction, both sides in the depth direction, and from the upper side in the vertical direction.

[0062] The recovery unit 170 includes a discharge unit 172 that discharges air toward the sheet material P being transported along the discharge path 42, and a suction unit 182 that sucks in the air discharged toward the sheet material P. Air is an example of a gas.

[0063] -Discharge section 172- 8, the discharge unit 172 includes a discharge duct 174 and a fan 176 that blows (discharges) air toward the sheet material P being conveyed through the discharge duct 174. Furthermore, the discharge unit 172 includes a guide portion 178 that is provided at a discharge port 174e of the discharge duct 174.

[0064] The discharge duct 174 is box-shaped and opens toward the discharge path 42, extending in the depth direction. The discharge duct 174 includes a ceiling panel 174a whose thickness direction is the up-down direction, a front panel 174b whose thickness direction is the width direction, and a back panel 174c whose thickness direction is the width direction and is located downstream of the front panel 174b in the sheet conveying direction. Furthermore, as shown in FIG. 10, the discharge duct 174 includes a pair of side panels 174d whose thickness direction is the depth direction.

[0065] Corotron 160 is disposed inside discharge duct 174. Specifically, as shown in FIG. 8, corotron 160 is disposed at the opening of discharge duct 174, with gap 180a provided between corotron 160 and front plate 174b when viewed from the depth direction. Furthermore, as shown in FIG. 10, corotron 160 is disposed with gaps 180b provided between corotron 160 and a pair of side plates 174d when viewed from the top-bottom direction. In other words, gaps 180b are formed between corotron 160 and a pair of side plates 174d on both sides of corotron 160 in the depth direction. In other words, discharge duct 174 protrudes from corotron 160 in the depth direction.

[0066] As shown in Fig. 7, a plurality of fans 176 are attached to the ceiling board 174a and are arranged side by side in the depth direction. As shown by the arrows in Fig. 8, the fans 176 are configured to blow (discharge) air toward the sheet material P being conveyed through the discharge duct 174. The fans 176 are an example of an airflow generating device.

[0067] 8 and 11(A), a plurality of guide portions 178 are provided at discharge port 174e of discharge duct 174, and are provided at intervals in the depth direction. Each guide portion 178 is plate-shaped, and an end portion 178a of guide portion 178 on the upstream side in the sheet conveying direction is positioned higher than an end portion 178b on the downstream side in the sheet conveying direction. Furthermore, end portion 178b is positioned lower than the bottom end of shield case 162.

[0068] In this configuration, the operating fan 176 causes the air inside the discharge duct 174 to flow toward the sheet member P (see arrow A in FIG. 8). Here, the air flowing toward the sheet member P is split into three paths before being discharged toward the sheet member P.

[0069] In the first path, air flowing in the direction of arrow A passes through through-holes 166 formed in the bottom plate 162a of shield case 162, flows inside shield case 162, and is discharged toward sheet member P (see arrow B in FIG. 8). In other words, air with a high ozone concentration around discharge wire 164 is discharged toward sheet member P. As a result, ozone generated by corona discharge is discharged toward sheet member P.

[0070] In the second path, air flowing in the direction of arrow A flows through gap 180a between corotron 160 and front plate 174b and is discharged toward sheet member P (see arrow C in FIG. 8). In other words, air flowing in the direction of arrow A is discharged toward sheet member P from discharge port 174e of discharge duct 174 (see arrow C in FIG. 8). The flow path area of ​​discharge duct 174 and the area and number of through holes 166 formed in bottom plate 162a of shield case 162 are determined so that the flow rate of air discharged toward sheet member P from discharge port 174e is faster than the flow rate of air flowing inside shield case 162.

[0071] In the third path, air flowing in the direction of arrow A flows through gaps 180b formed on both sides of corotron 160 in the depth direction and is discharged toward sheet member P (see arrow D in FIG. 10). As described above, the air inside discharge duct 174 flows through the first to third paths and is discharged toward sheet member P.

[0072] -Suction part 182- As shown in FIG. 8, the suction section 182 includes a suction duct 184 and a guide section 188 provided at a suction port 184e of the suction duct 184.

[0073] The suction duct 184 is box-shaped and opens toward the discharge path 42, extending in the depth direction. The suction duct 184 is disposed downstream of the discharge duct 174 in the sheet conveying direction. The suction duct 184 includes a ceiling panel 184a whose thickness direction is the up-down direction, a back panel 174c of the discharge duct 174, and a back panel 184c whose thickness direction is the width direction and is located downstream of the back panel 174c in the sheet conveying direction. Furthermore, as shown in FIG. 10 , the suction duct 184 includes a pair of side panels 184d whose thickness direction is the depth direction. In this way, the back panel 174c is a component that constitutes both the discharge duct 174 and the suction duct 184.

[0074] 8 and 11(B), a plurality of guide portions 188 are provided at suction port 184e of suction duct 184, and are provided at intervals in the depth direction. Each guide portion 188 is plate-shaped, and an end portion 188a on the upstream side in the sheet conveying direction of guide portion 188 is positioned higher than an end portion 188b on the downstream side in the sheet conveying direction. Furthermore, end portion 188b is positioned lower than the lower end of back panel 184c.

[0075] As shown in FIG. 1, one end of an exhaust duct 194 is connected to the ceiling plate 184a of the intake duct 184, and an exhaust fan 196 and an ozone filter 198 are provided at the other end of the exhaust duct 194.

[0076] In this configuration, the air discharged from the discharge duct 174 shown in Figure 8 through the first to third paths described above toward the sheet material P flows downstream in the sheet conveying direction, is sucked into the suction duct 184, and is exhausted.

[0077] (Function of main components) Next, the operation of the static eliminator 150 will be described together with the static eliminator 250 according to a comparative embodiment. First, the configuration of the static eliminator 250 according to the comparative embodiment will be described, focusing mainly on the differences from the static eliminator 150 according to this embodiment.

[0078] [Configuration of static eliminator 250] As shown in Figure 12, the comparative static eliminator 250 includes a corotron 160 and a fan 276 attached to a through hole (numeral omitted) formed in the bottom plate 162a of the shield case 162 of the corotron 160, which blows (exhausts) air through the inside of the shield case 162 toward the sheet member P side.

[0079] [Operation of the static eliminators 150 and 250] 1, the sheet material P transported inside the image forming apparatus 10 is charged with static electricity at the secondary transfer position NT where the toner image is transferred. The electrostatically charged sheet material P is transported along the discharge path 42 and faces the static eliminators 150 and 250.

[0080] A corona discharge occurs when a voltage is applied to the discharge wire 164 of the corotron 160 of the static eliminator 150, 250. This eliminates the static electricity charged on the sheet member P. Here, the corona discharge also generates ozone.

[0081] -Static eliminator 250- 12, in the static eliminator 250 according to the comparative embodiment, the operating fan 276 causes the air inside the shield case 162 to flow toward the sheet member P (see arrow E in FIG. 12). As a result, the air containing ozone generated by the corona discharge is expelled toward the sheet member P.

[0082] At both sides in the depth direction, the air flowing toward the sheet member P passes outside the paper guide 46 in the depth direction, flows below the paper guide 46, and is discharged (arrow F in FIG. 12).

[0083] On the other hand, the air flowing toward the sheet member P in the central portion in the depth direction hits the sheet member P and stagnates on the surface of the sheet member P.

[0084] -Static eliminator 150- In the static eliminator 150 according to this embodiment, as shown in FIG. 8, the operating fan 176 causes the air inside the discharge duct 174 to flow toward the sheet member P (see arrow A in FIG. 8).

[0085] After flowing in the direction of arrow A, the air that flows through the first path passes through through-holes 166 formed in bottom plate 162a of shield case 162, flows inside shield case 162, and is discharged toward sheet member P (see arrow B in FIG. 8). As a result, air containing ozone generated by corona discharge is discharged toward sheet member P.

[0086] Furthermore, the air that flows in the direction of arrow A and then flows through the second path is discharged from discharge port 174e of discharge duct 174 toward the sheet member P (see arrow C in FIG. 8).

[0087] Furthermore, the air that flows in the direction of arrow A and then flows through the third path flows through gaps 180b formed on both sides of corotron 160 in the depth direction and is discharged toward sheet member P (see arrow D in FIG. 10).

[0088] The ozone-containing air that flows from the inside of the discharge duct 174 through the first to third paths and is discharged toward the sheet material P flows downstream in the sheet conveying direction, is sucked into the suction duct 184, and is exhausted.

[0089] Thus, in the static eliminator 150 of this embodiment, unlike the static eliminator 250 of the comparative embodiment, the air containing ozone generated in the central part of the corotron 160 extending in the depth direction is prevented from stagnating on the surface of the sheet member P.

[0090] (summary) As described above, in static eliminator 150, air flowing toward the sheet member P side by operating fan 176 passes through through-holes 166 formed in bottom plate 162a of shield case 162, flows inside shield case 162, and is discharged toward the sheet member P side. Furthermore, the air discharged toward the sheet member P side flows downstream in the sheet conveyance direction, is sucked into suction duct 184, and is exhausted. As a result, compared to when static eliminator 250 according to the comparative embodiment is used, air containing ozone generated in the center portion of corotron 160 extending in the depth direction is prevented from stagnating on the surface of sheet member P.

[0091] Furthermore, in the static eliminator 150, air containing ozone generated by corona discharge is discharged toward the sheet material P, and the discharged air containing ozone flows downstream in the conveyance direction and is sucked into the suction duct 184. This suppresses an increase in the conveyance resistance imposed on the sheet material P, compared to when the air discharged toward the sheet material P flows upstream in the conveyance direction and is sucked into the suction duct.

[0092] Furthermore, in the static eliminator 150, air containing ozone generated by corona discharge is discharged toward the sheet material P, and the discharged air containing ozone is prevented from flowing upstream in the conveyance direction by air discharged from the discharge port 174e of the discharge duct 174 toward the sheet material P. This prevents the conveyed sheet material P from colliding with the resin plate and being damaged, compared to when a resin plate is used to prevent the air from flowing upstream.

[0093] In addition, in the static eliminator 150, the air flowing toward the sheet member P side by the operating fan 176 flows through a flow path that passes through the through-hole 166 formed in the bottom plate 162a of the shield case 162 and is discharged toward the sheet member P side, and also flows through a flow path that is discharged from the discharge port 174e of the discharge duct 174 toward the sheet member P side. In other words, the air flows through two flow paths are generated by the fan 176. In this way, parts are shared.

[0094] Furthermore, in static eliminator 150, air flowing at both ends of gap 180a is sucked into suction duct 184 without flowing below corotron 160 (see FIG. 10). This prevents air that has passed through corotron 160 and been expelled toward sheet member P from leaking to both sides in the depth direction.

[0095] Furthermore, in static eliminator 150, through-holes 166 through which air passes are formed in bottom plate 162a of shield case 162. This allows air to flow from corotron 160 toward sheet member P with a simpler configuration than when no through-holes are formed in the bottom plate of the shield case.

[0096] Furthermore, in static eliminator 150, the flow path area of ​​the air discharged from discharge port 174e of discharge duct 174 toward sheet material P and the opening area of ​​through hole 166 are determined so that the speed of the air discharged from discharge port 174e of discharge duct 174 toward sheet material P is faster than the speed of the air flowing from corotron 160 toward sheet material P. This prevents the air discharged from corotron 160 toward sheet material P from flowing upstream in the sheet conveying direction, compared to when the speed of the air discharged from discharge port 174e of discharge duct 174 toward sheet material P is slower than the speed of the air flowing from the corotron toward sheet material P.

[0097] Furthermore, in the image forming apparatus 10, ozone-containing air is prevented from stagnating inside the apparatus main body 10a, compared to when the image forming apparatus 10 includes the static eliminator 250 according to the comparative embodiment.

[0098] Second Embodiment An example of a static eliminator and an image forming apparatus according to a second embodiment of the present disclosure will be described with reference to Fig. 13. Note that, with regard to the second embodiment, differences from the first embodiment will be mainly described.

[0099] (Configuration of static eliminator 350) As shown in FIG. 13, the static elimination device 350 according to the second embodiment includes a corotron 160 that eliminates static electricity from a charged sheet member P by corona discharge, and a collection section 370 that collects ozone generated by the corona discharge.

[0100] The recovery section 370 includes a discharge section 372 that discharges air toward the sheet material P being transported through the inside of the corotron 160, and a suction section 182 that sucks in the air discharged toward the sheet material P. Air is an example of a gas.

[0101] 13, the discharge section 372 includes a discharge duct 374 and a fan 176 that flows (discharges) air toward the sheet material P being conveyed through the discharge duct 174. Furthermore, the discharge section 372 includes a guide member 378 attached to the lower edge of the discharge duct 374 on the upstream side in the sheet conveyance direction. The guide member 378 is an example of a suppression member.

[0102] The discharge duct 374 is box-shaped and opens toward the discharge path 42, extending in the depth direction. The discharge duct 374 includes a ceiling panel 374a whose thickness direction is the up-down direction, a front panel 374b whose thickness direction is the width direction, and a back panel 174c whose thickness direction is the width direction and is disposed downstream of the front panel 374b in the sheet conveyance direction. The discharge duct 374 also includes a pair of side panels (not shown) whose thickness direction is the depth direction. There is no gap between the front panel 374b and the shield case 162.

[0103] The guide member 378 extends in the depth direction and has an L-shaped cross section. Specifically, a lower end portion 380 of the guide member 378 extends downstream in the sheet conveying direction, and an upstream end 380a of the lower end portion 380 in the sheet conveying direction is positioned higher than a downstream end 380b of the lower end portion 380 in the sheet conveying direction. This suppresses the flow of ozone-containing air discharged toward the sheet member P side toward the upstream side in the sheet conveying direction.

[0104] (Action of the static eliminator 350) 13, in the static eliminator 350, an operating fan 176 causes air inside the discharge duct 374 to flow toward the sheet member P. The air flowing toward the sheet member P passes through the through-holes 166 formed in the bottom plate 162a of the shield case 162, flows inside the shield case 162, and is discharged toward the sheet member P. In this way, air containing ozone generated by corona discharge is discharged toward the sheet member P.

[0105] The ozone-containing air discharged toward the sheet member P flows downstream in the sheet conveying direction, while the flow toward the upstream side in the sheet conveying direction is restricted by the guide member 378. Furthermore, the air that flows downstream in the sheet conveying direction is sucked into the suction duct 184 and exhausted.

[0106] Although the present disclosure has been described in detail with respect to specific embodiments, it will be apparent to those skilled in the art that the present disclosure is not limited to such embodiments and that various other embodiments are possible within the scope of the present disclosure. For example, in the above-described embodiments, the static eliminators 150 and 350 are used in the image forming apparatus 10, but the static eliminators may also be used in post-processing devices connected to the image forming apparatus.

[0107] Furthermore, in the above embodiment, the corotron 160 is used for explanation, but any corona discharge electrode may be used, such as a scorotron.

[0108] In addition, in the above embodiment, the air flows from the upstream side to the downstream side in the sheet conveying direction along the sheet member P, but the air may flow from the downstream side to the upstream side. In this case, the effect achieved by the air flowing from the upstream side to the downstream side is not achieved.

[0109] Furthermore, in the first embodiment, the air flowing toward the sheet member P side by the operating fan 176 flows through a flow path that passes through the through-hole 166 formed in the bottom plate 162a of the shield case 162 and is discharged toward the sheet member P side, and through a flow path that is discharged from the discharge port 174e of the discharge duct 174 toward the sheet member P side. In other words, the air flows through two flow paths generated by the fan 176. However, separate fans may be provided for each flow path. In this case, the effect of sharing a fan will not be achieved.

[0110] (((1))) a corona discharge electrode facing the recording medium being conveyed and extending in a direction intersecting the recording medium conveyance direction; an airflow generating device that causes the gas around the corona discharge electrode to flow toward a recording medium; a suction duct that is disposed upstream or downstream of the corona discharge electrode in the transport direction, extends in the intersecting direction, and sucks in the gas that has been blown onto the recording medium by the airflow generating device; A static eliminator comprising:

[0111] (((2))) the suction duct is disposed downstream of the corona discharge electrode in the conveying direction; a suppression member extending in the intersecting direction and suppressing the gas flowing toward the recording medium from flowing toward the upstream side of the corona discharge electrode in the transport direction; The static eliminator according to (((1))).

[0112] (((3))) the suppression member extends in the intersecting direction and includes a discharge duct that discharges gas toward the recording medium upstream of the corona discharge electrode in the transport direction. The static eliminator according to (((2))).

[0113] (((4))) The airflow generating device discharges gas from the discharge duct. The static eliminator according to (((3))).

[0114] (((5))) The discharge duct and the suction duct extend in the intersecting direction and protrude toward the corona discharge electrode on both sides of the intersecting direction. The static eliminator according to (((3))) or (((4))).

[0115] (((6))) the corona discharge electrode includes a box-shaped shield case that opens toward a recording medium and extends in the intersecting direction, and a discharge wire that is disposed inside the shield case and extends in the intersecting direction, A through hole is formed in the bottom plate of the shield case, through which gas passes due to the gas flow generated by the airflow generating device. The static eliminator according to any one of (((1))) to (((5))).

[0116] (((7))) the suction duct is disposed downstream of the corona discharge electrode in the conveying direction; a discharge duct extending in the intersecting direction is provided, and the discharge duct discharges gas toward the recording medium on the upstream side of the corona discharge electrode in the transport direction by a gas flow generated by the airflow generating device; a flow path area of ​​the discharge duct and an opening area of ​​the through hole are determined so that the speed of the gas discharged from the discharge duct to the upstream side of the corona discharge electrode is faster than the speed of the gas flowing from the corona discharge electrode toward the recording medium; The static eliminator according to (((6))).

[0117] (((8))) a conveying unit that conveys the recording medium; an image forming unit that forms an image on the recording medium conveyed by the conveying unit; The static eliminator according to any one of (((1))) to (((7))) that eliminates static electricity from a charged recording medium that is transported while an image is formed thereon; An image forming apparatus comprising:

[0118] The static elimination device according to (((1))) can prevent ozone-containing gas generated in the central part of the corona discharge electrode extending in the intersecting direction from stagnating on the surface of the recording medium, compared to a case in which ozone-containing gas is discharged only from both ends of the recording medium in the intersecting direction that intersects the conveying direction of the recording medium.

[0119] The static eliminator according to (((2))) can suppress an increase in the transport resistance imposed on the recording medium, compared to when a gas flow occurs from the downstream side to the upstream side in the transport direction.

[0120] The static eliminator according to (((3))) can prevent the recording medium being transported from coming into contact with the resin plate and being damaged, compared to when a resin plate is used to suppress the flow of gas upstream.

[0121] The static eliminator according to (((4))) discharges gas from the discharge duct and flows gas with a high ozone concentration around the corona discharge electrode toward the recording medium, thereby reducing the number of parts compared to when separate airflow generating devices are used.

[0122] The static eliminator according to (((5))) can suppress leakage of ozone in the intersecting direction compared to a case where the corona discharge electrodes protrude toward the discharge duct and the suction duct on both sides of the intersecting direction.

[0123] The static elimination device according to (((6))) has a simple structure in which gas with a high ozone concentration around the corona discharge electrode flows toward the recording medium, compared to when no through holes are formed in the bottom plate of the shield case.

[0124] The static eliminator according to (((7))) can prevent the gas flowing from the corona discharge electrode to the recording medium from flowing upstream in the transport direction of the recording medium, compared to when the speed of the gas discharged from the discharge duct toward the recording medium is slower than the speed of the gas flowing from the corona discharge electrode toward the recording medium.

[0125] The image forming apparatus according to (((8))) can prevent ozone-containing gas from stagnating inside the apparatus, compared to an apparatus equipped with a static eliminator that discharges ozone-containing gas only from both ends of the recording medium in a direction intersecting the conveying direction of the recording medium. [Explanation of symbols]

[0126] 10 Image forming device 12 Image forming unit 44 Discharge roll (an example of a transport section) 150 Static eliminator 160 Corotron (an example of a corona discharge electrode) 162 Shield Case 162a bottom plate 164 Discharge Wire 166 Through Hole 174 Discharge duct 176 Fan (an example of an airflow generating device) 184 Discharge duct 350 Static eliminator 378 Guide member (an example of a restraining member)

Claims

1. a corona discharge electrode facing the recording medium being conveyed and extending in a direction intersecting the recording medium conveyance direction; an airflow generating device that causes the gas around the corona discharge electrode to flow toward a recording medium; a suction duct that is disposed upstream or downstream of the corona discharge electrode in the transport direction, extends in the intersecting direction, and sucks in the gas that has been blown onto the recording medium by the airflow generating device; A static eliminator comprising:

2. the suction duct is disposed downstream of the corona discharge electrode in the conveying direction; a suppression member extending in the intersecting direction and suppressing the gas flowing toward the recording medium from flowing toward the upstream side of the corona discharge electrode in the transport direction; The static eliminator according to claim 1 .

3. the suppression member includes a discharge duct extending in the intersecting direction and discharging gas toward the recording medium upstream of the corona discharge electrode in the transport direction. The static eliminator according to claim 2 .

4. The airflow generating device discharges gas from the discharge duct. The static eliminator according to claim 3 .

5. The discharge duct and the suction duct extend in the intersecting direction and protrude toward the corona discharge electrode on both sides of the intersecting direction. The static eliminator according to claim 3 or 4.

6. the corona discharge electrode includes a box-shaped shield case that opens toward a recording medium and extends in the intersecting direction, and a discharge wire that is disposed inside the shield case and extends in the intersecting direction, A through hole is formed in the bottom plate of the shield case, through which gas passes due to the gas flow generated by the airflow generating device. The static eliminator according to claim 1 .

7. the suction duct is disposed downstream of the corona discharge electrode in the conveying direction; a discharge duct extending in the intersecting direction is provided, and the discharge duct discharges gas toward the recording medium on the upstream side of the corona discharge electrode in the transport direction by a gas flow generated by the airflow generating device; a flow path area of ​​the discharge duct and an opening area of ​​the through hole are determined so that the speed of the gas discharged from the discharge duct to the upstream side of the corona discharge electrode is faster than the speed of the gas flowing from the corona discharge electrode toward the recording medium; The static eliminator according to claim 6.

8. a conveying unit that conveys the recording medium; an image forming unit that forms an image on the recording medium conveyed by the conveying unit; The static eliminator according to any one of claims 1 to 7, which eliminates static electricity from a charged recording medium that is being transported while an image is being formed thereon; An image forming apparatus comprising:

Images