Static elimination apparatus and image forming apparatus

Abstract

To provide a static elimination apparatus which enables reduction of transport failure when a sheet passes through a non-contact static elimination unit, and to provide an image forming apparatus.SOLUTION: A static elimination apparatus 300 includes a non-contact static elimination unit 61 to eliminate static from a sheet transported in a transport passage T while making no contact with the sheet. An upper guide member 64 forming a part of the transport passage T has: a plurality of ribs 640 which are disposed arranged in a width direction; and a plurality of openings 641 which expose the non-contact static elimination unit 61 to the transport passage T. The plurality of ribs 640 incline relative to a transport direction so that a distance from a transport center C becomes larger toward the downstream side in the transport direction.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a static eliminator that eliminates static electricity from a sheet and an image forming apparatus including the static eliminator. [Background technology]

[0002] In image forming apparatuses such as copying machines and facsimile machines, sheets may become charged during image formation, and discharged sheets may stick together due to the electrostatic force between the sheets. In response to this, an image forming apparatus equipped with a static elimination device that eliminates static electricity from sheets has been proposed. For example, Patent Document 1 describes a static elimination device equipped with a contact type static elimination unit (static elimination roller) that eliminates static electricity while in contact with the conveyed sheet, and a non-contact type static elimination unit (discharge wire) that eliminates static electricity without contacting the sheet.

[0003] In addition, in the static elimination device of Patent Document 1, a portion of the transport path along which the sheet is transported where the non-contact static elimination unit is arranged is formed by a guide member (shielding member) having a plurality of openings. The non-contact static elimination unit is exposed to the transport path through the plurality of openings provided in the guide member, so that the non-contact static elimination unit can eliminate static electricity from the sheet being transported. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2021-111527 A Summary of the Invention [Problem to be solved by the invention]

[0005] When the transport path in the non-contact static electricity removing section is formed by a guide member having an opening, the corners of the leading edge of the transported sheet may enter the opening, causing wrinkles in the sheet and resulting in transport failure.

[0006] SUMMARY OF THE PRESENT EMBODIMENTS In view of the above, an object of the present invention is to provide a static eliminator and an image forming apparatus capable of reducing transport defects when a sheet passes through a non-contact static eliminator. [Means for solving the problem]

[0007] One aspect of the present invention is a static elimination device comprising: a conveying section that conveys a sheet along a conveying path; a non-contact static elimination section that eliminates static electricity from the sheet conveyed by the conveying section without coming into contact with the sheet conveyed by the conveying section; a guide section that contacts the sheet conveyed by the conveying section to guide the sheet; and a plurality of openings arranged side by side in a sheet width direction perpendicular to the sheet conveying direction and exposing the non-contact static elimination section to the conveying path, the first guide member forming a part of the conveying path; and a second guide member arranged opposite the first guide member and forming a part of the conveying path together with the first guide member, wherein the guide section includes a plurality of first ribs arranged on one side of a conveying center in the sheet width direction and a plurality of second ribs arranged on the other side of the conveying center in the sheet width direction, and the plurality of first ribs and the plurality of second ribs are shaped so that the distance from the conveying center increases toward the downstream side in the sheet conveying direction. Effect of the Invention

[0008] According to the present invention, it is possible to provide a static eliminator and an image forming apparatus capable of reducing transport defects when a sheet passes through a non-contact static eliminator. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is an overall view of an image forming apparatus. [Diagram 2] FIG. [Diagram 3] FIG. [Figure 4] FIG. [Diagram 5] FIG. [Figure 6] FIG. 4 is an enlarged view showing the rear side of the upper guide member of the apparatus. [Figure 7] FIG. 4 is a perspective view of the upper guide member as viewed from the transport path side. [Figure 8] FIG. 4 is an enlarged view showing a rib of the upper guide member. [Figure 9] FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The dimensions, materials, shapes, relative positions, and the like of the components described in the following embodiments are not intended to limit the scope of application of the present technology, unless otherwise specified.

[0011] <Image forming device> FIG. 1 is an overall view of the hardware configuration of an image forming apparatus 1000 according to the present embodiment. The image forming apparatus 1000 includes a printing apparatus 100, an inserter 200, a static eliminator 300, and a large-capacity stacker 400. The printing apparatus 100 forms an image on a sheet based on an instruction from an external device (not shown). The inserter 200 conveys a sheet conveyed from the printing apparatus 100 to the static eliminator 300. The inserter 200 also feeds an insertion sheet from a feed tray 201, and is capable of inserting the insertion sheet between a plurality of sheets conveyed from the printing apparatus 100. The static eliminator 300 neutralizes the sheet conveyed from the printing apparatus 100 via the inserter 200. The large-capacity stacker 400 is a large-capacity stacker that stacks sheets conveyed from the static eliminator 300. The sheet conveyed from the printing device 100 through the inserter 200 and the static eliminator 300 is discharged onto a discharge tray 401 of a large-capacity stacker 400 .

[0012] Although the image forming apparatus 1000 in this embodiment includes the printing apparatus 100, the inserter 200, the static eliminator 300, and the large-capacity stacker 400, the configuration of the image forming apparatus 1000 is not limited to this. For example, the image forming apparatus 1000 may be configured to further include another finisher downstream of the large-capacity stacker 400. The image forming apparatus 1000 may be configured such that the static eliminator 300 is directly connected to the printing apparatus 100, and does not include the inserter 200 or the large-capacity stacker 400. The image forming apparatus 1000 may be configured such that the static eliminator 300 is integrally provided inside the housing 110 (FIG. 2) of the printing apparatus 100.

[0013] <Printing device> 2 is a schematic cross-sectional view of the printing device 100. The printing device 100 in this embodiment is a tandem type multifunction device (having the functions of a copier, printer, and facsimile machine) that employs an intermediate transfer method. The printing device 100 can form a full-color image on a sheet (transfer material, sheet material, recording medium, media) P such as paper using an electrophotographic method in response to an image signal transmitted from an external device, for example.

[0014] The printing device 100 has, as a plurality of image forming units (stations), four image forming units 10Y, 10M, 10C, and 10K that form images of yellow (Y), magenta (M), cyan (C), and black (K), respectively. These image forming units 10Y, 10M, 10C, and 10K are arranged in a row along the moving direction of an image transfer surface that is arranged substantially horizontally of an intermediate transfer belt 7, which will be described later. Elements in each of the image forming units 10Y, 10M, 10C, and 10K that have the same or corresponding functions or configurations may be generally described by omitting the suffixes Y, M, C, and K that indicate that the element is for one of the colors. The image forming unit 10 has photosensitive drums 1 (1Y, 1M, 1C, 1K), chargers 2 (2Y, 2M, 2C, 2K), exposure devices 3 (3Y, 3M, 3C, 3K), developing devices 4 (4Y, 4M, 4C, 4K), primary transfer rollers 5 (5Y, 5M, 5C, 5K), and cleaning devices 6 (6Y, 6M, 6C, 6K).

[0015] The photosensitive drum 1, which is a rotatable drum-type (cylindrical) photosensitive body serving as a first image carrier that carries a toner image, receives a driving force from a drum drive motor (not shown) and is driven to rotate in the direction of arrow R1 (counterclockwise) in FIG. 2. The surface of the rotating photosensitive drum 1 is uniformly charged to a predetermined potential of a predetermined polarity (negative polarity in this embodiment) by a charger 2 serving as a charging means. During charging, a predetermined charging voltage is applied to the charger 2 by a charging power source (not shown). The surface of the charged photosensitive drum 1 is scanned and exposed by an exposure device 3 serving as an exposure means in accordance with an image signal, and an electrostatic latent image is formed on the photosensitive drum 1. In this embodiment, the exposure device 3 is configured as a laser scanner device that irradiates the photosensitive drum 1 with a laser beam modulated in accordance with image information. The electrostatic image formed on the photosensitive drum 1 is developed by a developer 4 serving as a developing means that supplies toner as a developer, and a toner image is formed on the photosensitive drum 1. In this embodiment, toner charged with the same polarity as the charge polarity of the photosensitive drum 1 adheres to an exposed portion on the photosensitive drum 1, which has been uniformly charged and then exposed to light to reduce the absolute value of the potential. The developing unit 4 has a developing roller, which is a rotatable developer carrier that carries the developer and transports it to a developing position facing the photosensitive drum 1. The developing roller is rotated by, for example, a driving force transmitted from a drive system of the photosensitive drum 1. During development, a predetermined developing voltage is applied to the developing roller by a developing power source (not shown).

[0016] An intermediate transfer belt 7, which is a rotatable intermediate transfer body formed of an endless belt as a second image carrier that carries a toner image, is disposed so as to face the four photosensitive drums 1Y, 1M, 1C, and 1K. The intermediate transfer belt 7 is stretched around a plurality of tension rollers, including a drive roller 22, an upstream auxiliary roller 23a, a downstream auxiliary roller 23b, a tension roller 25, a secondary transfer pre-roller 24, and an inner roller 21, and stretched with a predetermined tension (tension). The drive roller 22 transmits a driving force to the intermediate transfer belt 7. The tension roller 25 applies a predetermined tension to the intermediate transfer belt 7 and controls the tension of the intermediate transfer belt 7 to be constant. The secondary transfer pre-roller 24 forms a surface of the intermediate transfer belt 7 in the vicinity of the upstream of the secondary transfer nip N2 with respect to the rotation direction of the intermediate transfer belt 7. The inner roller 21 functions as an opposing member of the outer roller 9. The upstream auxiliary roller 23a and the downstream auxiliary roller 23b form a substantially horizontal image transfer surface. The driving roller 22 is driven to rotate by a driving force transmitted from a belt driving motor (not shown). As a result, the intermediate transfer belt 7 receives a driving force from the driving roller 22 and rotates in the direction of the arrow R2 in FIG. 2 (clockwise). In this embodiment, the intermediate transfer belt 7 is driven to rotate at a peripheral speed of 150 to 470 mm / sec. The tension rollers other than the driving roller 22 among the plurality of tension rollers are rotated in accordance with the rotation of the intermediate transfer belt 7. Primary transfer rollers 5Y, 5M, 5C, and 5K, which are roller-shaped primary transfer members as primary transfer means, are arranged on the inner peripheral surface side of the intermediate transfer belt 7 in correspondence with each of the photosensitive drums 1Y, 1M, 1C, and 1K. The primary transfer roller 5 presses the intermediate transfer belt 7 toward the photosensitive drum 1 to form a primary transfer nip N1 as a primary transfer portion, which is a contact portion between the photosensitive drum 1 and the intermediate transfer belt 7. Further, on the inner peripheral surface side of the intermediate transfer belt 7, a pressing member 26 is provided upstream of the inner roller 21 and downstream of the pre-secondary transfer roller 24 in the rotation direction of the intermediate transfer belt 7. The pressing member 26 comes into contact with the inner peripheral surface of the intermediate transfer belt 7 and presses the intermediate transfer belt 7 from the inner peripheral surface side to the outer peripheral surface side.

[0017] The toner image formed on the photosensitive drum 1 as described above is primarily transferred onto the rotating intermediate transfer belt 7 at the primary transfer nip N1 by the action of the primary transfer roller 5. During the primary transfer, a primary transfer voltage, which is a DC voltage of a polarity opposite to the normal charging polarity of the toner (positive polarity in this embodiment) is applied to the primary transfer roller 5 by a primary transfer power source (not shown). For example, when a full-color image is formed, the toner images of each color of yellow, magenta, cyan, and black formed on each photosensitive drum 1 are primarily transferred in sequence so as to be superimposed on the same image forming area on the intermediate transfer belt 7. In this embodiment, the primary transfer nip N1 is an image forming position where a toner image is formed on the intermediate transfer belt 7. The intermediate transfer belt 7 is an example of a rotatable endless belt that transports the toner image carried at the image forming position.

[0018] An outer roller 9, which is a roller-shaped secondary transfer member serving as a secondary transfer means, is disposed at a position facing the inner roller 21 on the outer peripheral surface side of the intermediate transfer belt 7. The outer roller 9 is pressed against the inner roller 21 via the intermediate transfer belt 7 to form a secondary transfer nip N2, which is a contact portion between the intermediate transfer belt 7 and the outer roller 9, as a secondary transfer portion. The toner image formed on the intermediate transfer belt 7 as described above is secondarily transferred onto the sheet P, which is sandwiched and conveyed between the intermediate transfer belt 7 and the outer roller 9, by the action of the outer roller 9 in the secondary transfer nip N2. During the secondary transfer, a secondary transfer voltage, which is a constant-voltage controlled DC voltage of a polarity opposite to the normal charging polarity of the toner (positive polarity in this embodiment), is applied to the outer roller 9 by the secondary transfer power source 18. In this embodiment, for example, a secondary transfer voltage of +1 to +7 KV is applied, and a secondary transfer current of +40 to +120 μA is caused to flow, so that the toner image on the intermediate transfer belt 7 is secondarily transferred onto the sheet P. In this embodiment, the inner roller 21 is electrically grounded (connected to ground). Alternatively, the inner roller 21 may be used as a secondary transfer member, to which a secondary transfer voltage having the same polarity as the normal charging polarity of the toner is applied, and the outer roller 9 may be used as a counter electrode, which is electrically grounded.

[0019] The sheet P is conveyed to the secondary transfer nip N2 in synchronization with the toner image on the intermediate transfer belt 7. That is, the sheet P stored in a recording material cassette 11 serving as a recording material storage section is conveyed to the registration rollers 8 by a feed roller or the like and stopped there. The sheet P is then sent to the secondary transfer nip N2 by the registration rollers 8 being rotationally driven so that the toner image on the intermediate transfer belt 7 coincides with a desired image forming area on the sheet P at the secondary transfer nip N2. In terms of the sheet conveying direction of the sheet P (hereinafter simply referred to as the conveying direction), a conveying guide 14 for guiding the sheet P to the secondary transfer nip N2 is provided downstream of the registration rollers 8 and upstream of the secondary transfer nip N2.

[0020] The sheet P onto which the toner image has been transferred is conveyed by the pre-fixing conveying section 41 to the fixing section 40 as a fixing means. The pre-fixing conveying section 41 has a rotatable belt body made of a rubber material such as EPDM, having a width of 100 to 110 mm and a thickness of 1 to 3 mm, at the center in the sheet width direction (hereinafter simply referred to as the width direction) perpendicular to the conveying direction of the sheet P. The pre-fixing conveying section 41 conveys the sheet P on the belt body. The belt body has holes with a diameter of 3 to 7 mm, and the sheet P is supported by the belt body. The belt body has holes with a diameter of 3 to 7 mm, and the sheet P is supported by the belt body. The belt body is provided with holes for sucking air from the inner peripheral surface side, thereby increasing the support force of the sheet P and stabilizing the conveyance of the sheet P. The fixing section 40 applies heat and pressure to the sheet P carrying the unfixed toner image during the process of sandwiching the sheet P carrying the unfixed toner image between the pair of fixing rotors and conveying the sheet P, thereby fixing (melting and fixing) the toner image to the surface of the sheet P. The sheet P on which the toner image has been fixed is then conveyed to the inserter 200 by the pair of exit rollers 42.

[0021] Meanwhile, the toner remaining on the photosensitive drum 1 after the primary transfer is removed from the photosensitive drum 1 and collected by a cleaning device 6 serving as a cleaning means. Also, the toner remaining on the intermediate transfer belt 7 after the secondary transfer and the adhering matter such as paper powder adhering from the sheet P are removed from the intermediate transfer belt 7 and collected by a belt cleaning device 12 serving as an intermediate transfer body cleaning means. In this embodiment, the belt cleaning device 12 electrostatically collects and cleans the adhering matter such as the secondary transfer residual toner on the intermediate transfer belt 7.

[0022] In this embodiment, an intermediate transfer belt unit 20 serving as a belt conveying device is configured by including the intermediate transfer belt 7 stretched over a plurality of tension rollers, the primary transfer rollers 5, the belt cleaning device 12, and a frame supporting these. The intermediate transfer belt unit 20 is supported detachably on the housing 110 of the printing device 100 for maintenance or replacement. Here, the intermediate transfer belt 7 may be one made of a resin-based material having a single layer or multi-layer structure, or one having a multi-layer structure with an elastic layer made of an elastic material.

[0023] In this embodiment, the primary transfer roller 5 is configured by providing an elastic layer made of ion-conductive foamed rubber on the outer periphery of a metal core material. In this embodiment, the primary transfer roller 5 has an outer diameter of 15 to 20 mm, and an electrical resistance of 1×10 when measured by applying a voltage of 2 kV in an environment of 23° C. and 50% RH. 5 ~1×10 8 It is Omega.

[0024] In this embodiment, the outer roller 9 is configured by providing an elastic layer of ion-conductive foamed rubber on the outer periphery of a metal core material. In this embodiment, the outer roller 9 has an outer diameter of 20 to 25 mm, and an electrical resistance of 1×10 when measured by applying a voltage of 2 kV in an environment of 23° C. and 50% RH. 5 ~1×10 8 The outer roller 9 is in contact with the inner roller 21 with a predetermined pressure across the intermediate transfer belt 7, forming a secondary transfer nip N2.

[0025] In this embodiment, the inner roller 21 is configured by providing an elastic layer of electronically conductive rubber on the outer periphery of a metal core material. In this embodiment, the inner roller 21 has an outer diameter of 20 to 22 mm, and an electrical resistance of 1×10 when measured by applying a voltage of 50 V in an environment of 23° C. and 50% RH. 5 ~1×10 8 Ω. The secondary transfer pre-roller 24 can have a configuration similar to that of the inner roller 21. In this embodiment, the rotation axes of the tension rollers of the intermediate transfer belt 7 including the inner roller 21 and the outer roller 9 are substantially parallel to each other.

[0026] <Static eliminator> Next, the static eliminator 300 according to this embodiment will be described with reference to FIG. 3. FIG. 3 is a schematic cross-sectional view of the static eliminator 300. In the image forming apparatus 1000, the static eliminator 300 is disposed downstream of the printing device 100 and the inserter 200. The sheet P may become charged by the image forming process of the printing device 100 described above. When the sheet P becomes charged, multiple sheets P discharged onto the discharge tray 401 may stick together due to electrostatic force, which may lead to stacking failure. Therefore, in this embodiment, the static eliminator 300 performs a static elimination process on the sheet P on which an image is formed by the printing device 100.

[0027] The static eliminator 300 has a static elimination roller pair 50 as a contact static elimination section that eliminates static electricity from a sheet in a state of contact with the sheet (contact state), and a non-contact static elimination section 60 that eliminates static electricity from a sheet without contacting the sheet (non-contact state). The static elimination device 300 also has an entrance roller pair 43 that receives the sheet from the inserter 200 and conveys it along the conveying path T, and an exit roller pair 44 that discharges the sheet, which has been neutralized by the static elimination roller pair 50 and the non-contact static elimination section 60, to the large-capacity stacker 400. The entrance roller pair 43 and the exit roller pair 44 are an example of a conveying section in this embodiment.

[0028] The pair of static elimination rollers 50 is composed of a static elimination roller 51 which rotates in contact with the lower surface of the sheet, and a static elimination counter roller 52 which rotates in contact with the upper surface of the sheet. The static elimination roller 51 is composed of an elastic layer of ion conductive foamed rubber provided on the outer periphery of a metal core material. In this embodiment, the static elimination roller 51 has an outer diameter of 20 to 25 mm, and an electrical resistance of 1×10 when measured by applying a voltage of 2 kV in an environment of 23° C. and 50% RH. 5 ~1×10 8 For example, the charge removing roller 51 can be made of the same material as the above-mentioned outer roller 9. The charge removing opposing roller 52 has an outer diameter of 20 to 25 mm, and together with the charge removing roller 51 forms a charge removing nip portion N3.

[0029] The sheet conveyed from the printing apparatus 100 is first roughly removed of electrostatic charge by the discharge nip portion N3 of the discharge roller pair 50. A discharge voltage, which is a constant voltage controlled DC voltage of opposite polarity (negative polarity in this embodiment) to the secondary transfer member (outer roller 9) is applied to the discharge roller 51 by a discharge power source 53. In this embodiment, for example, a discharge voltage of -1 to -7 KV is applied. The discharge device 300 is provided with a switch 54, and an operator can use the switch 54 to switch ON / OFF of the application of voltage to the discharge roller pair 50. The discharge opposing roller 52 is electrically grounded (connected to ground).

[0030] The sheet that has passed through the pair of discharging rollers 50 is then discharged by a non-contact discharger 60 provided downstream of the pair of discharging rollers 50. The non-contact discharger 60 removes the charge of the sheet that has not been completely discharged by the pair of discharging rollers 50. The non-contact discharger 60 is composed of a non-contact discharge unit 61 (first non-contact discharge unit, upper discharge unit) provided above the conveying path T, and a non-contact discharge unit 62 (second non-contact discharge unit, lower discharge unit) provided below the conveying path T. That is, in this embodiment, the non-contact discharge units 61 and 62 are arranged on both the upper and lower sides of the conveying path T in the non-contact discharger 60. In this embodiment, the non-contact discharge units 61 and 62 are ionizers that include discharge needles 61a and 62a that generate ions for discharging the sheet, and irradiate ions toward the sheet conveyed through the discharge region 60a to discharge the sheet. The static elimination needle 61a is an example of a first ion emitting portion, and the static elimination needle 62a is an example of a second ion emitting portion. However, as the non-contact static elimination units 61 and 62, for example, a non-contact static elimination unit equipped with a discharge wire may be used.

[0031] Furthermore, the non-contact static electricity eliminating section 60 is provided with a guide unit 63 that forms a part (static electricity eliminating region 60a) of the transport path T. The guide unit 63 is disposed below the non-contact static electricity eliminating unit 61 and above the non-contact static electricity eliminating unit 62 in the vertical direction. That is, the guide unit 63 is disposed between the non-contact static electricity eliminating unit 61 and the non-contact static electricity eliminating unit 62. In the non-contact static electricity eliminating section 60, when the sheet passes through the guide unit 63, static electricity is eliminated by the non-contact static electricity eliminating units 61 and 62. In this embodiment, the sheet is delivered from the static electricity eliminating roller pair 50 to the guide unit 63.

[0032] <Guide unit> 4 is a perspective view of the guide unit 63. The guide unit 63 is composed of an upper guide member 64 (first guide member) that faces the upper surface of the sheet to guide the sheet, and a lower guide member 65 (second guide member) that faces the lower surface of the sheet to guide the sheet. The lower guide member 65 forms a charge removal area 60a of the conveying path T together with the upper guide member 64, and the sheet that has passed through the charge removal roller pair 50 is conveyed between the upper guide member 64 and the lower guide member 65. In this embodiment, the upper guide member 64 and the lower guide member 65 are made of an insulating resin material and have a volume resistivity of 1×10 14 The upper guide member 64 and the lower guide member 65 are fixed to each other by a plurality of screws 66 provided at both ends in the width direction, and form a single guide unit 63.

[0033] The upper guide member 64 is provided with a plurality of ribs 640 arranged in the width direction and a plurality of openings 641 formed between the plurality of ribs 640. The plurality of ribs 640 provided on the upper guide member 64 are upper surface guide parts that contact and guide the upper surface of the sheet. The plurality of ribs 640 are formed extending in a direction inclined with respect to the conveying direction. For example, the angle (the angle formed) of the ribs 640 with respect to the conveying direction is in the range of 20° to 50°. The plurality of openings 641 expose the static electricity elimination needles 61a of the non-contact static electricity elimination unit 61 to the conveying path T. Similarly to the upper guide member 64, the lower guide member 65 is provided with a plurality of ribs 650 arranged in the width direction and a plurality of openings 651 formed between the plurality of ribs 650. The plurality of ribs 650 provided on the lower guide member 65 are lower surface guide parts that contact and guide the lower surface of the sheet. 4, in order to prevent the drawing from becoming complicated, only some of the ribs 640, 650 and the openings 641, 651 are labeled with reference numerals. In this embodiment, the upper guide member 64 and the lower guide member 65 have the same shape.

[0034] The ribs 640 of the upper guide member 64 contact the upper surface of the sheet to guide the sheet, and the ribs 650 of the lower guide member 65 contact the lower surface of the sheet to guide the sheet. Ions emitted from the non-contact static electricity eliminating unit 61 pass through the opening 641 of the upper guide member 64 and are irradiated onto the upper surface of the sheet. Ions emitted from the non-contact static electricity eliminating unit 62 pass through the opening 651 of the lower guide member 65 and are irradiated onto the lower surface of the sheet. In this way, since the openings 641, 651 are formed in the guide unit 63, the ions emitted from the non-contact static electricity eliminating units 61, 62 are not physically blocked, and therefore the non-contact static electricity eliminating section 60 can eliminate static electricity from the sheet.

[0035] <Guide member shape> Next, the shape of the upper guide member 64 will be described. In this embodiment, the lower guide member 65 has the same shape as the upper guide member 64, so the description of the lower guide member 65 will be omitted. FIG. 5 is a top view of the upper guide member 64. In FIG. 5, the conveying center C is the center position of the area in the width direction where the sheet is conveyed. The upper guide member 64 includes a plurality of ribs 640 (640a to 640l), a plurality of openings 641 (641a to 641m), and a frame portion 642 that configures the outer periphery of the upper guide member 64. The ribs 640a to 640f are an example of a first rib arranged on the device inner side (one side) from the conveying center C, and the ribs 640g to 640l are an example of a second rib arranged on the device front side (the other side) from the conveying center C.

[0036] FIG. 6 is an enlarged view of the upper guide member 64 on the rear side of the device. In the upper guide member 64, the interval between two adjacent ribs 640 at a position close to the conveying center C is larger than the interval between two adjacent ribs 640 at a position far from the conveying center C. Specifically, the width of the opening 641f between the ribs 640e and 640f close to the conveying center C is larger than the opening 641b between the ribs 640a and 640b far from the conveying center C. In this embodiment, the openings 641d, 641e, and 641f are equal in size. In this embodiment, the ribs 640a to 640f arranged on the rear side of the device and the ribs 640g to 640l arranged on the front side of the device are arranged symmetrically with respect to the conveying center C. In other words, the upper guide member 64 has a shape that is symmetrical in the width direction. Therefore, the width of the opening 641h between the rib 640g and the rib 640h close to the conveying center C is larger than the width of the opening 641l between the rib 640k and the rib 640l far from the conveying center C. In this way, since the multiple ribs 640 are arranged symmetrically in the width direction with respect to the conveying center C, the conveying resistance applied to the conveyed sheet becomes approximately the same on the left and right, and skewing of the sheet is suppressed.

[0037] The region W in FIG. 5 is a region with a width of 250 mm centered on the conveying center C. In the region W of the upper guide member 64, the multiple ribs 640 are arranged so that only one rib 640 abuts against the end of the sheet in the width direction. That is, in the region W, the multiple ribs 640 (640c to 640j) are arranged so that they do not overlap each other when viewed in the conveying direction. On the other hand, outside the region W, the multiple ribs 640 are arranged so that two ribs 640 abut against the end of the sheet. That is, outside the region W, the multiple ribs 640 (640a, 640b, 640k, 640l) are arranged so that they overlap each other when viewed in the conveying direction. By arranging the multiple ribs 640 in this manner, the width of the opening 641 is increased in the region W at the center in the width direction, so that the charge removal efficiency by the non-contact charge removal unit 60 can be improved. Furthermore, outside the region W in the width direction, the two ribs 640 come into contact with the edge of the sheet, so that the conveying performance for a wide sheet can be improved.

[0038] When the upper guide member 64 is viewed from above, the ratio (opening ratio) of the total area of ​​the multiple openings 641 to the entire area (frame portion 642) of the upper guide member 64 is 60% or more. The upper guide member 64 is shaped such that the ratio of the openings 641 to the entire area (frame portion 642) of the upper guide member 64 is 60% or more regardless of the position in the width direction. Since the opening ratio of the upper guide member 64 is 60% or more, the ions generated from the non-contact static electricity removing unit 61 are efficiently irradiated onto the sheet.

[0039] 5, the ribs 640 of the upper guide member 64 are inclined with respect to the transport direction so that the distance from the transport center C increases toward the downstream side in the transport direction. In other words, the ribs 640 are inclined with respect to the transport direction so that they move toward the outside in the width direction toward the downstream side in the transport direction. Specifically, the ribs 640a to 640f arranged on the rear side of the device are inclined toward the rear side of the device, and the ribs 640g to 640l arranged on the front side of the device are inclined toward the front side of the device. For example, the rib 640a arranged on one side of the transport center C and the rib 640l arranged on the other side of the transport center C are inclined in directions away from each other toward the downstream side in the transport direction.

[0040] Next, the shape of the rib 640 will be described in detail. Fig. 7 is a perspective view of the upper guide member 64 viewed from the transport path T side. Fig. 8 is an enlarged view of the rib 640 (640g). Fig. 9 is a side view of the rib 640 of the upper guide member 64 and the rib 650 of the lower guide member 65 viewed from the width direction. In this embodiment, the ribs 640h to 640l have the same shape as the rib 640g, and the ribs 640a to 640f have shapes symmetrical to the rib 640g with respect to the transport center C.

[0041] The rib 640 of the upper guide member 64 has an inclined portion 643 (first inclined portion) inclined so that the distance between the rib 640 and the lower guide member 65 becomes smaller toward the downstream side in the conveying direction, and a downstream guide portion 644 extending from the inclined portion 643 to the downstream side in the conveying direction. The inclined portion 643 constitutes the upstream side of the guide surface (top) of the rib 640 that contacts the sheet, and the downstream guide portion 644 constitutes the downstream side of the guide surface (top) of the rib 640. The rib 650 of the lower guide member 65 has an inclined portion 653 (second inclined portion) inclined so that the distance between the rib 640 and the upper guide member 64 becomes smaller toward the downstream side in the conveying direction, and a downstream guide portion 654 extending from the inclined portion 653 to the downstream side in the conveying direction. The downstream guide portion 644 and the downstream guide portion 654 are surfaces extending parallel to the conveying direction. 9, the conveying path T is shaped such that the gap in the thickness direction of the sheet (the space through which the sheet passes) is large on the upstream side in the conveying direction and the space through which the sheet passes becomes narrower toward the downstream side in the conveying direction due to the shapes of the inclined portion 643 and the inclined portion 653. Here, the inclined portion 643 and the inclined portion 653 may have a shape extending in a curved shape when viewed from the width direction.

[0042] Further, the rib 640 has a side inclined portion 645 formed continuously from the inclined portion 643 and the downstream guide portion 644, and a side surface 646 formed continuously from the side inclined portion 645. The side inclined portion 645 is formed continuously from the end portion farther from the conveying center C of the inclined portion 643 and the downstream guide portion 644, and is a surface that is inclined so as to move away from the lower guide member 65 as it moves away from the conveying center C. The side surface 646 is a surface that extends in the conveying direction and in the vertical direction (sheet thickness direction). The side inclined portion 645 is a surface that connects the downstream guide portion 644 and the side surface 646.

[0043] When a sheet is transported from the pair of static electricity removing rollers 50 to the non-contact static electricity removing unit 60, the corners of the leading edge of the sheet may enter the openings 641, 651. In such a case, the above-mentioned side inclined portion 645 scoops up the edge of the sheet and guides it to the inclined portion 643 and the downstream guide portion 644.

[0044] As described above, the rib 640 of the upper guide member 64 has the inclined portion 643 that is inclined so as to approach the lower guide member 65 toward the downstream side in the conveying direction. Therefore, the portion of the inclined portion 643 in the conveying path T has a slope shape in which the space through which the sheet passes is wider toward the upstream side in the conveying direction. This makes it possible to reduce the occurrence of a jam caused by the leading end of the sheet hitting the upper guide member 64, even when a sheet with a curled leading end is conveyed. Furthermore, since the space through which the sheet passes is narrower toward the downstream side in the conveying direction, the behavior of the sheet in the static elimination area 60a is stabilized, and it is possible to reduce conveyance failures when the sheet is neutralized by the non-contact static elimination unit 60.

[0045] Similarly to the ribs 640 of the upper guide member 64, the ribs 650 of the lower guide member 65 have inclined portions 653 that are inclined so as to approach the upper guide member 64 toward the downstream side in the conveying direction. Therefore, it is possible to further reduce the occurrence of jams when the sheet is conveyed to the guide unit 63.

[0046] Moreover, the rib 640 of the upper guide member 64 is provided to extend at an incline with respect to the conveying direction so as to move away from the conveying center C toward the downstream side in the conveying direction. Furthermore, the rib 640 of the upper guide member 64 has a side inclined portion 645 which is a surface that is inclined so as to move away from the lower guide member 65 as it moves away from the conveying center C. As a result, the end of the sheet being conveyed first comes into contact with the side inclined portion 645 and is then handed over to the inclined portion 643 and the downstream guide portion 644, making it possible to reduce the occurrence of a jam caused by the end of the sheet hitting the side surface 646.

[0047] In this embodiment, the lower guide member 65 has the same shape as the upper guide member 64, so that it is possible to further reduce the occurrence of jams, but the lower guide member 65 may have a different shape from the upper guide member 64. For example, the rib 650 of the lower guide member 65 may be configured to guide the sheet only by the downstream guide portion 654 without providing the inclined portion 653.

[0048] In this embodiment, the guide portion of the guide member that guides the sheet is configured by a plurality of ribs 640, 650, but the configuration of the guide portion is not limited to this. For example, the guide portion of the guide member may be configured by a surface on which a plurality of openings aligned in the width direction are formed. In this case, it is preferable that the plurality of openings provided on the guide surface of the guide member are disposed at positions corresponding to the static elimination needles 61a, 62a.

[0049] In addition, in this embodiment, the ribs 640, 650 extend linearly when viewed from above, but the shape of the ribs 640, 650 is not limited to this. For example, the ribs 640, 650 may be provided in a curved shape when viewed from above.

[0050] In the present embodiment, the non-contact static electricity removing section 60 of the static electricity removing device 300 is provided with the non-contact static electricity removing units 61, 62 on both the upper and lower sides of the transport path T, but the configuration of the static electricity removing device 300 is not limited to this. For example, the static electricity removing device 300 may be configured such that only the non-contact static electricity removing unit 61 is provided on the upper side of the transport path T. In the present embodiment, the static electricity removing device 300 is provided with both the non-contact static electricity removing section 60 and the static electricity removing roller pair 50, but the static electricity removing device 300 may be configured such that only the non-contact static electricity removing section 60 is provided. [Explanation of symbols]

[0051] 50 Antistatic roller pair 60 Non-contact static elimination unit 61, 62 Non-contact static elimination unit 63 Guide unit 64 Upper guide member 65 Lower guide member 100 Printing equipment 300 Static eliminator 640, 650 Ribs 641, 651 aperture 643, 653 Slope

Claims

1. a conveying unit that conveys the sheet along a conveying path; a non-contact static elimination unit that eliminates static electricity from the sheet conveyed by the conveyance unit in a non-contact state; a first guide member that forms a part of the conveying path and that includes a first rib that contacts the sheet conveyed by the conveying unit to guide the sheet and an opening that exposes the non-contact static eliminating unit to the conveying path; a second guide member disposed opposite the first guide member and forming a part of the transport path together with the first guide member; Equipped with the first rib has an outer side surface formed continuously from the top of the first rib and disposed farther from the conveyance center than the top in a sheet width direction perpendicular to the sheet conveyance direction, The outer side surface is inclined so as to move away from the second guide member as it moves away from the conveyance center. A static eliminator characterized by:

2. The first rib has a shape that is inclined with respect to the sheet conveying direction so that the distance from the conveying center increases as the first rib moves downstream in the sheet conveying direction.

2. The static eliminator according to claim 1.

3. The first guide member is a fifth rib that is disposed on the other side of the conveyance center in the sheet width direction and contacts the sheet to guide the sheet; the fifth rib has a shape inclined with respect to the sheet conveying direction so that a distance from the conveying center increases toward a downstream side in the sheet conveying direction; 3. The static eliminator according to claim 2.

4. The first guide member has a plurality of first ribs arranged on one side of the conveying center in the sheet width direction, and a plurality of fifth ribs arranged on the other side of the conveying center in the sheet width direction.

4. The static eliminator according to claim 3.

5. The first rib has an upstream inclined portion on the upstream side in the sheet conveying direction, which is inclined so that the distance between the first rib and the second guide member becomes smaller as the first rib moves downstream in the sheet conveying direction.

2. The static eliminator according to claim 1.

6. The opening is arranged to overlap the upstream inclined portion in the sheet conveying direction.

6. The static eliminator according to claim 5.

7. The first rib is formed continuously from the top of the first rib and has an inner side surface arranged closer to the conveying center than the top in the sheet width direction, the predetermined direction is a direction perpendicular to the sheet width direction and the sheet conveying direction, extending from the top portion toward the conveying path through which the sheet passes, an angle formed between the outer side surface and the predetermined direction is smaller than an angle formed between the inner side surface and the predetermined direction; 2. The static eliminator according to claim 1.

8. The first guide member is a plurality of ribs including the first rib, which come into contact with the sheet conveyed by the conveying unit and guide the sheet; a sidewall inclined portion disposed on one side of a rib disposed most downstream on one side in the seat width direction among the plurality of ribs; and the sidewall inclined portion is inclined so as to approach the second guide member as it moves away from the conveyance center; 2. The static eliminator according to claim 1.

9. The first rib has a shape that is inclined with respect to the sheet conveying direction so that the distance from the conveying center increases as the first rib moves downstream in the sheet conveying direction, the side wall inclined portion has a shape extending parallel to the sheet conveying direction; 9. The static eliminator according to claim 8.

10. The first guide member has, on one side of the conveying center in the sheet width direction, the first rib, a second rib adjacent to the first rib, a third rib located outside the first rib and the second rib in the sheet width direction, and a fourth rib adjacent to the third rib; the first rib, the second rib, the third rib, and the fourth rib each have the outer side surface; 2. The static eliminator according to claim 1.

11. In the seat width direction, the distance between the third rib and the fourth rib is shorter than the distance between the first rib and the second rib. The static eliminator according to claim 10 .

12. The first guide member has a first opening formed between the first rib and the second rib, a second opening formed between the third rib and the fourth rib, and In the sheet width direction, the width of the first opening is larger than the width of the second opening. The static eliminator according to claim 10 .

13. The first rib and the second rib are arranged so as not to overlap in the sheet width direction, The third rib and the fourth rib are arranged to overlap each other in the seat width direction. The static eliminator according to claim 10 .

14. a pair of static elimination rollers that contact the sheet and eliminate static electricity are provided upstream of the non-contact static elimination unit; 2. The static eliminator according to claim 1.

15. the non-contact static eliminator is a first non-contact static eliminator disposed above the first guide member, a second non-contact static elimination unit disposed below the second guide member and configured to eliminate static electricity from the sheet conveyed by the conveyance unit in a non-contact state; The second guide member has a shape similar to that of the first guide member.

2. The static eliminator according to claim 1.

16. The static eliminator according to any one of claims 1 to 13; an image forming unit having a transfer unit that transfers a toner image onto a sheet, and a fixing unit that applies heat and pressure to the sheet onto which the toner image has been transferred by the transfer unit to fix the toner image onto the sheet; Equipped with the static eliminator is disposed downstream of the image forming unit and eliminates static electricity from a sheet on which an image is formed by the image forming unit; An image forming apparatus characterized by:

Images