JP2009229943A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus in which the charge of a sheet is surely removed so that the sheet is excellently separated from an image carrier by facilitating the assembling work of a separate needle with a contact part and stabilizing the contact state of the separate needle with the contact part. <P>SOLUTION: The cylindrical outer surface of a first contact spring (compression coil spring) 28 comes into contact with the separate needle substrate 24 of a separate electrode 25 in the generatrix direction of the cylindrical outer surface. Thus, in the assembling work of the separate needle substrate 24 with the first contact spring 28, the separate needle substrate 24 and the first contact spring 28 are hardly damaged, so that the assembling work of the separate needle substrate 24 with the first contact spring 28 is facilitated. Further, the contact of the first contact spring 28 with the separate needle substrate 24 is stabilized to surely remove the charge of the sheet 12. As a result, the sheet 12 is excellently separated from a photoreceptor drum 2, to reduce the occurrence of a jam (paper jam) caused by the separation failure between the sheet 12 and the photoreceptor drum 2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile, and the like. The present invention relates to an image forming apparatus.

  In general, in an image forming apparatus such as an electrophotographic copying machine, a printer, or a facsimile, a toner image is formed or transferred on the surface of an image carrier such as a photosensitive drum or an intermediate transfer member, and the surface of the image carrier. After the formed or transferred toner image is transferred to a sheet (copy paper, plastic film, etc.), the sheet is separated from the surface of the image carrier by a separating means, and the separated sheet is sent to the fixing means. After fixing the toner image on the sheet by the fixing means, the fixed sheet is conveyed to a discharge tray, an intermediate tray for double-sided printing, or the like.

  As the separation means of such an image forming apparatus, for example, a neutralization separation system as shown in FIG. 9 (see Patent Document 1), a neutralization separation system as shown in FIG. 10 (see Patent Document 2), The thing of the static elimination separation system shown in FIG. 11 (refer patent document 3) is known. Among them, the separating means 100 and 101 shown in FIGS. 9 and 10 have the upstream side wall portions 104 and 105 positioned on the upstream side in the sheet conveying direction and the downstream side wall portion 106 positioned on the downstream side in the sheet conveying direction. , 107, and a plurality of separation needles 102, 103 are arranged in a direction orthogonal to the sheet conveying direction (hereinafter, abbreviated as a paper passing width direction). Further, the separating means 108 shown in FIG. 11 has a plurality of predetermined intervals along the longitudinal direction of the image carrier 114 on the downstream side in the sheet conveying direction of the transfer charger 109 arranged to face the image carrier 114. When the separation needle 110 having the discharge tip portion 110 a is arranged and a voltage is applied to the separation needle 110, a discharge current flows from the separation needle 110 and the sheet 112 is separated from the image carrier 114. ing.

  Among the separating units 100, 101, and 108 of such an image forming apparatus, the separating unit 100 disclosed in Patent Document 1 is configured such that the separation voltage is applied to the separating needle 102 at a predetermined timing after the toner image is transferred to the sheet 111. Is applied, a corona discharge is generated between the separation needle 102 and the image carrier 113, and static electricity charged on the sheet 111 in the transfer operation by the transfer roller 117 is removed, and the sheet 111 is removed from its own waist. The image carrier 113 is separated from the image carrier 113 by strength, dead weight, or the like.

  Further, the separation unit 101 disclosed in Patent Document 2 discharges excessive charges from the back surface side of the sheet 115 to the grounded separation needle 103 side, and eliminates static electricity charged on the sheet 115 by the transfer operation by the transfer roller 120. It is supposed to be. Even when the separation unit 101 disclosed in Patent Document 2 that has been conventionally known is used, if the sheet 115 itself is strong, the charge removal between the sheet 115 and the image carrier 116 is performed. It was possible to perform the separation well.

  Further, the separation means 108 disclosed in Patent Document 3 separates the sheet 112 from the image carrier 114 after the toner image on the image carrier 114 is transferred onto the sheet 112. The separation conditions at this time When a predetermined voltage is applied to the separation needle 110 and the distance between the separation needle 110 and the image carrier 114 is set to a predetermined value, when the transfer corona is generated by the transfer charger 109, the surrounding impedance fluctuates and is separated. A discharge current is observed from the needle 110 and the sheet 112 is well separated from the image carrier 114.

  By the way, in recent years, printing is frequently performed on both sides of a sheet from the viewpoint of effectively using resources and protecting the environment. When printing on both sides of such a sheet, there is a possibility that the separation means 101 as disclosed in the conventional patent document 2 cannot satisfactorily separate the sheet 115 from the image carrier 116. Here, as a mode of printing on both sides of the sheet 115, after printing on one side of the sheet 115, a double-sided printing unit or the like is used, and the single-side printed sheet 115 is reversed so that the sheet 115 is printed. In addition to double-sided printing that continuously prints on the other side, the copy paper after single-sided printing is reused as the sheet 115, and printing is performed on the unprinted side of the reused sheet 115. There is also an aspect which performs.

  That is, when performing such double-sided printing, the curl (curvature deformation) of the sheet 115 such as copy paper tends to be larger than the curl of the sheet 115 only for single-sided printing, and the curl of the sheet 115 is the photosensitive member. When it is easy to wind around the image carrier 116 side such as a drum (when curled toward the image carrier 116 side), it becomes difficult to separate from the image carrier 116 as the curl increases, There is a possibility that the sheet 115 is wound up to the image carrier 116 side and causes a problem such as a jam (paper jam).

In order to solve such a problem, for example, in the separation means 100 and 108 of Patent Document 1 and Patent Document 3, a voltage having a polarity opposite to the transfer current is applied to the separation needles 102 and 110 to separate the separation needles 102 and 110. It is effective to discharge the sheets 111 and 112 by corona discharge between the image carriers 113 and 114 and to increase the separation efficiency of the sheets 111 and 112 from the image carriers 113 and 114.
Japanese Patent Laid-Open No. 9-218623 JP-A-8-137358 Japanese Patent Publication No. 7-40158

  In the conventional image forming apparatus as shown in FIGS. 9 to 11, as shown in FIG. 12, the leaf spring 131 is used at the contact portion with the separation needle 130, and the separation needle 130 is connected to the leaf spring 131. It was connected to the voltage supply unit 133 or the grounding unit 134 of the apparatus main body via the conducting wire 132.

  However, when the cantilever-shaped leaf spring 131 as shown in FIG. 12 is used as a contact portion with the separation needle 130, when the separation needle 130 and the leaf spring 131 are assembled, the leaf spring 131 is elastically deformed. Both (the separation needle 130 and the leaf spring 131) must be assembled while maintaining the state of being held, and there is a problem that the assembling work of the separation needle 130 and the leaf spring 131 is difficult.

  Further, as described above, since the assembling work of the separation needle 130 and the leaf spring 131 is difficult, the contact portion of the leaf spring 131 or the separation needle 130 is damaged (the shape is changed to a shape different from the design shape). Further, the contact state between the leaf spring 131 and the separation needle 130 becomes unstable, and there is a possibility that the charge removal failure of the sheet 135 may occur.

  Therefore, the present invention facilitates the assembly operation of the separation needle and the contact portion, stabilizes the contact state between the separation needle and the contact portion, and ensures the neutralization of the sheet, so that the sheet can be removed from the image carrier. Provided is an image forming apparatus which can be satisfactorily separated from the image forming apparatus.

  According to the first aspect of the present invention, a transfer current is applied to a sheet as a recording medium that passes between (1) an image carrier that carries and rotates a toner image, and (2) the toner image. And (3) along a sheet passing width direction that is positioned so as to be exposed to the sheet conveying path downstream of the transfer means and orthogonal to the sheet conveying direction. When a separation voltage is applied to a plurality of separation needles, the sheet is discharged between the image carrier and the separation needle, and the sheet charged by the transfer means is discharged to separate from the image carrier. And an image forming apparatus including the separating unit. In the present invention, the separating means includes a conductive separation electrode part integrally formed with the plurality of separation needles, and a conductive part electrically connecting the separation electrode part and the separation voltage supply part. Have. In addition, at least a portion of the conductive portion that contacts the separation electrode portion is constituted by a compression coil spring. The compression coil spring is accommodated in the spring receiving space of the separation means accommodating portion that accommodates the separation electrode portion in a compressed state and with its center line extending along the sheet passing width direction. The outer surface is pressed against the separation electrode portion.

  A second aspect of the invention relates to a configuration of the conductive portion in the image forming apparatus according to the first aspect of the invention. In other words, in the present invention, when the compression coil spring is a first compression coil spring, the conductive portion is separated from the end of the wire that forms the first compression coil spring extending from one end of the first compression coil spring. A second compression coil spring that contacts the voltage supply unit is integrally provided. According to the present invention, the separation voltage supply unit and the separation electrode unit are connected to each other through the conductive unit by pressing the end portion in the height direction of the second compression coil spring against the separation voltage supply unit. It is characterized by being electrically connected.

  According to a third aspect of the present invention, a transfer current is applied to a sheet as a recording medium passing between (1) a rotating image bearing member and (2) a toner image. And (3) along a sheet passing width direction that is positioned so as to be exposed to the sheet conveying path downstream of the transfer means and orthogonal to the sheet conveying direction. An image forming apparatus comprising: a plurality of separating needles that are grounded via a grounding unit on the apparatus body side; and a separation unit that neutralizes the sheet charged by the transfer unit and separates the sheet from the image carrier. It is about. In the present invention, the separation means includes a conductive separation electrode portion in which the plurality of separation needles are integrally formed, and a conductive portion that electrically connects the separation electrode portion and the grounding portion on the apparatus body side. ,have. In addition, at least a portion of the conductive portion that contacts the separation electrode portion is constituted by a compression coil spring. The compression coil spring is accommodated in the spring receiving space of the separation means accommodating portion that accommodates the separation electrode portion in a compressed state and with its center line extending along the sheet passing width direction. The outer surface is pressed against the separation electrode portion.

  A fourth aspect of the present invention relates to a configuration of the conductive portion in the image forming apparatus according to the third aspect of the present invention. That is, in the present invention, if the compression coil spring is a first compression coil spring, the conductive portion is connected to the end of the wire rod forming the first compression coil spring extending from one end of the first compression coil spring. A second compression coil spring that is in contact with the conducting wire connected to the grounding portion on the main body side is integrally provided. In the present invention, when the end of the second compression coil spring in the height direction is pressed against the conducting wire, the grounding portion and the separation electrode portion are electrically connected via the conducting wire and the conducting portion. It is characterized by being connected to.

  A fifth aspect of the present invention relates to a configuration of the first compression coil spring in the image forming apparatus according to the second or fourth aspect of the present invention. That is, in the present invention, the first compression coil spring is characterized in that spring stop protrusions that protrude into the spring receiving space are fitted in the internal spaces at both ends thereof.

  According to the present invention, the cylindrical outer surface of the compression coil spring comes into contact with the separation electrode portion along the generatrix direction, and the separation electrode portion and the compression coil spring are damaged during the assembly operation of the separation electrode portion and the compression coil spring. As a result, the assembly operation of the separation electrode portion and the compression coil spring is facilitated, the contact between the compression coil spring and the separation electrode portion is stabilized, and the sheet can be reliably discharged. As a result, according to the present invention, the sheet can be satisfactorily separated from the image carrier, and the occurrence of a jam (paper jam) due to poor separation between the sheet and the image carrier can be reduced.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[First Embodiment]
(Structure of image forming apparatus)
FIG. 1 shows a schematic configuration of an image forming apparatus 1 according to the present embodiment. In FIG. 1, a photosensitive drum (image carrier) 2 rotates in a direction indicated by an arrow A in FIG. 3, the surface is uniformly charged, and laser light is irradiated by the exposure unit 5 that operates based on a control signal from the control unit 4, and an electrostatic latent image is formed on the surface, and then the developing unit 6 is formed on the surface. Thus, toner as a developer is supplied, and the electrostatic latent image is visualized as a toner image.

  A sheet (copy paper, plastic film, or the like) 12 fed from the paper feed tray 7 or the manual feed tray 8 by the paper feed means 10 and 11 is transferred to the photosensitive drum 2 and the transfer roller (transfer means) 14 by the registration roller 13. Is sent to the transfer position P. The transfer roller 14 applies a transfer bias having a polarity opposite to that of the toner to the sheet 12, thereby transferring the toner image attached to the surface of the photosensitive drum 2 (in this embodiment, the photosensitive drum 2 and the transfer roller 14). The nip portion) P is transferred to the sheet 12. Note that the toner remaining on the surface of the photosensitive drum 2 without being transferred to the sheet 12 is removed by the cleaning unit 15. Further, as the photosensitive drum 2, an amorphous silicon type is used.

  A separating unit 16 is disposed adjacent to the transfer roller 14 at a predetermined position downstream of the transfer position P in the sheet conveying direction. The separation means 16 applies a separation voltage to the separation needle (separation electrode portion) 17 to generate a corona discharge between the separation drum 16 and the photosensitive drum 2, and removes the sheet 12 from the photosensitive drum 2. Further, a separation claw 18 is provided around the photosensitive drum 2 and between the separation unit 16 and the cleaning unit 15 to separate and separate the sheet 12 that could not be separated by the separation unit 16 from the surface of the photosensitive drum 2. Is arranged.

  The sheet 12 from which the charge is removed from the photosensitive drum 2 by the separating unit 16 is guided by the conveyance guide 19 and sent to the fixing unit 20, and is heated and pressurized by the fixing unit 20 to fix the toner. Then, the sheet sent out from the fixing unit 20 is discharged to the paper discharge tray 22 by the paper discharge roller 21 and is stacked on the paper discharge tray 22. The conveyance guide 19 is formed of a conductive metal plate, and has substantially the same dimensions as the sheet passing width direction (direction perpendicular to the sheet conveyance direction) of the sheet 12 conveyed through the sheet conveyance path 23. Dimension is formed.

(Structure of separation means)
FIG. 2 shows details of the separating means 16. In FIG. 2, the separating means 16 includes a separation electrode portion 25 (see FIG. 3) in which a plurality of separation needles 17 are formed at the tip of a thin plate-like separation needle substrate 24, and a separation needle 17 of the separation electrode portion 25. A separation voltage supply unit 26 for applying a separation voltage to the gate electrode and a conductive unit 27 that electrically connects the separation voltage supply unit 26 and the separation electrode unit 25 are provided. The separation electrode portion 25 and a part of the conductive portion 27 (first contact spring 28) in contact with the separation electrode portion 25 are accommodated in the separation means accommodation portion 30.

  As shown in FIG. 2, the separating unit accommodating portion 30 formed on the apparatus main body 31 side is a recess opening in the sheet conveyance path 23, and the sheet passing width direction (sheet conveyance) of the sheet 12 passing through the sheet conveyance path 23. In the direction perpendicular to the direction) and to the vicinity of both ends of the sheet conveyance path 23 in the sheet passing width direction. FIG. 4 is a partial plan view of the separating unit accommodating portion 30 as viewed from the sheet conveying path 23 side. In FIG. 4, the separation electrode portion 25 is indicated by a two-dot chain line, and the relationship between the first contact spring 28 and the separation electrode portion 25 is schematically shown.

  As shown in FIGS. 2 and 4, the separating unit accommodation unit 30 is positioned adjacent to the transfer unit accommodation unit 32 that rotatably supports the transfer roller 14, and is more in the sheet conveyance direction than the transfer unit accommodation unit 32. Located downstream. In the separation means accommodating portion 30, a separation needle holder 33 and a conductive portion holder 36 are accommodated and fixed to the apparatus main body 31, respectively. Among them, the separation needle holder 33 is for detachably fixing the separation needle substrate 24, and is an engagement protrusion corresponding to a plurality of attachment holes 34 formed along the longitudinal direction of the separation needle substrate 24. A plurality of 35 are formed, and the engagement protrusions 35 are engaged with the mounting holes 34 of the separation needle substrate 24 (see FIG. 3). The separation electrode unit 25 is fixed to the separation needle holder 33 so that the side surface of the separation needle substrate 24 is in close contact with the side surface of the separation needle holder 33, and is positioned downstream of the separation needle holder 33 in the sheet conveying direction. Is arranged.

  Further, as shown in FIGS. 2 and 4, the conductive portion holder 36 is separated so as to be opposed to the separation needle substrate 24 (so as to be located downstream of the separation needle substrate 24 in the sheet conveying direction). It is accommodated in the means accommodating portion 30. The conductive portion holder 36 is formed with a spring mounting portion 37 for accommodating a first contact spring (compression coil spring) 28 serving as a contact on the separation electrode portion 25 side of the conductive portion 27 in a part in the sheet passing width direction. . The spring attachment portion 37 is formed with a spring receiving space 38 that accommodates the first contact spring 28 in a compressed state, and abuts against both ends of the first contact spring 28 in the height direction, thereby the first contact spring 28. The spring receiving surfaces 40 and 40 that support 28 are formed. The spring mounting portion 37 is formed with a pair of spring stop projections 41, 41 fitted into the internal spaces on both end sides in the height direction of the first contact spring 28. The spring stop protrusions 41 are formed integrally with a pair of spring receiving surfaces 40 and 40 positioned so as to be orthogonal to the paper passing width direction of the spring mounting portion 37, and project into the spring receiving space 38. Here, the first contact spring 28 engaged with the pair of spring stop protrusions 41, 41 has a center line positioned substantially parallel to the sheet passing width direction, and a separation electrode at the generatrix position of the cylindrical outer surface. It comes into contact with the separation needle substrate 24 of the portion 25.

  As shown in FIGS. 2 and 4, the separating means accommodating portion 30 has a spring pressing protrusion 43 that protrudes into the spring receiving space 38 on the side face 42 that faces the separating needle substrate 24. The spring pressing protrusion 43 presses the cylindrical outer surface of the first contact spring 28 accommodated in the spring receiving space 38 toward the separation needle substrate 24, and the first contact spring 28 and the separation needle substrate 24. The first contact spring 28 is reliably brought into contact with the separation needle substrate 24.

  In FIG. 2, the lower end side of the spring mounting portion 37 opens downward in FIG. 2, and the first contact spring 28 can be mounted in the spring receiving space 38 from the opening 44. And the conducting wire 45 which is a spring wire which comprises the 1st contact spring 28 is extended below the opening part 44 of the lower end side of the spring attachment part 37 of FIG. A spring (compression coil spring) 46 is integrally formed. The second contact spring 46 is held in a compressed state in the height direction between the frame 47 on the apparatus main body 31 side and the separation voltage supply unit 26, and the lower end side thereof is pressed against the separation voltage supply unit 26. (See FIG. 2). As a result, the separation voltage supply unit 26 and the separation electrode unit 25 are electrically connected via the conductive unit 27.

  3 is formed of a conductive material (for example, SUS304 or the like), and at least the sheet passing width direction dimension (sheet 12) of the largest sheet 12 of the sheets 12 used for printing. In the direction perpendicular to the conveying direction). A plurality of separation needles 17 project from the edge of the separation electrode portion 30 on the photosensitive drum 2 side in the sheet passing width direction (see FIGS. 2 and 3). The separation needle 17 has a substantially triangular shape when viewed in the paper passing direction (see FIG. 3), and converges toward the photosensitive drum 2 side, and between the tip and the photosensitive drum 2. Discharge occurs. Note that the leading end of the separation needle 17 is disposed at a position where it does not contact the sheet 12 moving along the sheet conveyance path 23.

  According to the present embodiment configured as described above, the first contact spring 28 is a compression coil spring, and the cylindrical outer surface of the first contact spring 28 is in contact with the separation needle substrate 24 along the generatrix direction. Therefore, when the separation electrode unit 25 and the separation needle holder 33 are attached to the separation unit accommodation unit 30 (when the separation electrode unit 25 and the separation needle holder 33 are attached to the separation unit accommodation unit 30 by being lowered from the upper position in FIG. 2), When the separation electrode portion 25 and the separation needle holder 33 are pushed into the space between the first contact spring 28 and the inner wall 48 of the separation means housing portion 30, the separation needle substrate 24 and the separation needle holder 33 of the separation electrode portion 25 cause the first change. The one-contact spring 28 is elastically deformed in the radial direction, and the mounting operation of the separation electrode unit 25 and the separation needle holder 33 to the separation unit housing unit 30 is performed easily and smoothly.

  Further, according to the present embodiment, when the separation electrode portion 25 and the separation needle holder 33 are mounted on the separation means housing portion 30, the cylindrical outer surface of the first contact spring 28 is separated along the generatrix direction. 24, the first contact spring 28 is not easily damaged, and a stable contact state between the first contact spring 28 and the separation needle substrate 24 can be maintained.

[Second Embodiment]
FIG. 5 shows a schematic configuration of the image forming apparatus 1 according to the present embodiment. FIG. 6 is a diagram showing details of the separating means 51 according to this embodiment. The image forming apparatus 1 according to the present embodiment is the same as the image forming apparatus 1 according to the first embodiment except for a part of the structure of the separating unit 51. Further, the structure of the separating means 51 of this embodiment is the same as the structure of the separating means 16 of the first embodiment except for a part of the configuration of the conductive part 52 and a part of the structure of the separation electrode part 25. It is. Therefore, in the description of the present embodiment, the same components as those of the image forming apparatus 1 and the separation unit 16 of the first embodiment are denoted by the same reference numerals, and the description overlapping with the first embodiment is omitted.

  In the image forming apparatus 1 according to the present embodiment, the separation unit 51 includes the separation needle 17 (separation electrode unit 25) electrically connected to the ground unit 53 of the apparatus main body 31 via the conductive unit 52. Is grounded. Such separation means 51 grounds excess charge accumulated in the sheet (transferred sheet) 12 sent from the nip between the photosensitive drum 2 and the transfer roller 14 to the downstream side in the sheet conveying direction from the back side of the sheet 12. The sheet 12 is discharged to the side of the separation needle 17 to neutralize static electricity charged on the sheet 12, and the sheet 12 is separated from the photosensitive drum 2 by the stiffness and weight of the sheet 12 itself. In the present embodiment, as shown in FIG. 7, the separation electrode unit 25 has a larger number of separation needles 17 than the first embodiment, and the interval between the adjacent separation needles 17 and 17 is the same as that of the first embodiment. The distance between the separation needles 17 and 17 is narrower.

  The conductive part 52 includes a first conductive part 54 extending from the separation electrode part 25 side and a second conductive part 55 extending from the transport guide 19 side. One end of the first conductive portion 54 in the direction along the center line of the second contact spring 46 is pressed against the conducting wire 56 of the second conductive portion 55 extending from the conveyance guide 19, and the grounding portion on the conveyance guide 19 and the apparatus main body 31 side. It is electrically connected to the grounding part 53 on the apparatus main body 31 side through a second conductive part 55 that electrically connects to the terminal 53 (see FIGS. 5, 6, and 8). Here, the second conductive portion 55 is an end portion in a direction along the center line of the conveyance guide side contact spring (compression coil spring) 57 at a portion in contact with the conveyance guide 19, and is connected to the grounding portion 53 on the apparatus main body 31 side. The portion to be connected is one end portion in the direction along the center line of the grounding portion side contact spring (compression coil spring) 58. Here, the contact spring 58 on the grounding portion side of the second conductive portion 55 is in direct contact with the grounding portion 53 on the device body 31 side or on the grounding portion 53 on the device body 31 side through another conductive portion. Electrically connected.

  Even if the sheet 12 is neutralized by the separating means 51, a small amount of static electricity remains. Therefore, when the conveyance guide 19 is grounded as in the present embodiment, the sheet 12 is attracted to the conveyance guide 19 side, and the sheet 12 is easily conveyed along the surface of the conveyance guide 19. The leading end of the sheet 12 can be accurately guided to the nip N between the heating roller 20a and the pressure roller 20b.

  The present invention can be widely applied to an image forming apparatus such as an electrophotographic copying machine, a printer, a facsimile machine, and a multifunction machine of these.

1 is a schematic configuration diagram of an image forming apparatus according to a first embodiment of the present invention. It is a block diagram which shows the relationship with the isolation | separation means based on 1st Embodiment of this invention, a photoreceptor drum, and a transfer roller. It is a front view of the separation electrode part of the separation means. FIG. 5 is a partial plan view of a separating unit accommodating portion as viewed from the sheet conveyance path side. It is a schematic block diagram of the image forming apparatus which concerns on 2nd Embodiment of this invention. It is a block diagram which shows the relationship with the isolation | separation means based on 2nd Embodiment of this invention, a photoreceptor drum, and a transfer roller. It is the perspective view which looked at the separation electrode part of the separation means from diagonally upward. It is a perspective view which shows the structure of the electroconductive part which concerns on 2nd Embodiment of this invention. It is a partial block diagram of an image forming apparatus showing a first conventional example. It is a partial block diagram of an image forming apparatus showing a second conventional example. It is a partial block diagram of the image forming apparatus which shows a 3rd prior art example. It is a block diagram which shows an example of the isolation | separation means in the conventional image forming apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 2 ... Photosensitive drum (image carrier), 12 ... Sheet, 14 ... Transfer roller (transfer means), 16, 51 ... Separation means, 17 ... Separation needle, 23 ... ... Sheet conveying path 25... Separation electrode section 26... Separation voltage supply section 27 and 52... Conductive section 28... First contact spring (compression coil spring) 30. ... Main body, 38 ... Spring receiving space, 41 ... Spring stopper projection, 45 ... Conducting wire (wire), 46 ... Second contact spring (compression coil spring), 53 ... Grounding section, 56 ... Conducting wire

Claims (5)

An image carrier that carries and rotates a toner image;
Transfer means for applying a transfer current to a sheet as a recording medium passing between the image carrier and transferring a toner image to the sheet;
A separation voltage is applied to a plurality of separation needles positioned so as to be exposed in the sheet conveyance path on the downstream side in the sheet conveyance direction with respect to the transfer unit and arranged along the sheet passing width direction orthogonal to the sheet conveyance direction. And separating means for discharging between the image carrier and the separation needle, and discharging the sheet charged by the transfer means to separate it from the image carrier;
In an image forming apparatus comprising:
The separation means includes a conductive separation electrode part in which the plurality of separation needles are integrally formed, and a conductive part that electrically connects the separation electrode part and the separation voltage supply part,
The conductive part is composed of a compression coil spring at least at a part in contact with the separation electrode part,
The compression coil spring is accommodated in the spring receiving space of the separation means accommodating portion that accommodates the separation electrode portion in a compressed state and with its center line extending along the sheet passing width direction. Side surfaces are pressed against the separation electrode part,
An image forming apparatus. When the compression coil spring is a first compression coil spring, the conductive portion is in contact with the separated voltage supply unit at an end of a wire that forms the first compression coil spring extending from one end of the first compression coil spring. Integrally having a second compression coil spring;
When the end of the second compression coil spring in the height direction is pressed against the separation voltage supply unit, the separation voltage supply unit and the separation electrode unit are electrically connected via the conductive unit. ,
The image forming apparatus according to claim 1. An image carrier that carries and rotates a toner image;
Transfer means for applying a transfer current to a sheet as a recording medium passing between the image carrier and transferring a toner image to the sheet;
A grounding portion on the apparatus main body side is provided with a plurality of separation needles positioned so as to be exposed in the sheet conveyance path downstream of the transfer unit and in the sheet conveyance width direction perpendicular to the sheet conveyance direction. Separating means for grounding the sheet, and discharging the sheet charged by the transfer means to separate it from the image carrier;
In an image forming apparatus comprising:
The separation means includes a conductive separation electrode portion in which the plurality of separation needles are integrally formed, and a conductive portion that electrically connects the separation electrode portion and the grounding portion on the apparatus main body side. ,
The conductive part is composed of a compression coil spring at least at a part in contact with the separation electrode part,
The compression coil spring is accommodated in the spring receiving space of the separation means accommodating portion that accommodates the separation electrode portion in a compressed state and with its center line extending along the sheet passing width direction. Side surfaces are pressed against the separation electrode part,
An image forming apparatus. When the compression coil spring is a first compression coil spring, the conductive portion is connected to the end of the wire that forms the first compression coil spring extending from one end of the first compression coil spring, and to the grounding portion on the apparatus main body side. Integrally having a second compression coil spring in contact with the connected conductor;
When the end portion in the height direction of the second compression coil spring is pressed against the conducting wire, the grounding portion and the separation electrode portion are electrically connected via the conducting wire and the conductive portion.
The image forming apparatus according to claim 3. In the first compression coil spring, spring stop protrusions that protrude into the spring receiving space are fitted in internal spaces at both ends thereof.
The image forming apparatus according to claim 2, wherein the image forming apparatus is an image forming apparatus.

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