JP2018169453A - Image forming apparatus - Google Patents

Abstract

To provide an image forming apparatus that can reduce insufficient or excessive elimination of static electricity on a medium after transfer, compared with a configuration where only a non-contact static eliminating member is provided downstream of a transfer area, and a configuration where a static eliminating member in contact with a medium is added to a portion immediately downstream of a non-contact static eliminating member.SOLUTION: An image forming apparatus comprises: a transfer member Rt that transfers an image held on an image holding body PR to a medium; a first static eliminating member 6 that is arranged downstream of the transfer member Rt in the medium conveyance direction and eliminates static electricity on the medium; a second static eliminating member 37 that is arranged downstream of the first static eliminating member 6 in the medium conveyance direction and eliminates static electricity on the medium; and a third static eliminating member 21 that is arranged between the first static eliminating member 6 and second static eliminating member 37 in the medium conveyance direction and has the same potential as that of the first static eliminating member 6.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an image forming apparatus.

  In the electrophotographic image forming apparatus, the techniques described in the following Patent Documents 1 to 3 are conventionally known as a technique for discharging the medium after the image is transferred and peeling the medium from the image carrier.

  In JP-A-2006-90630 as Patent Document 1, a sawtooth-shaped detack saw (6) is arranged on the downstream side of the transfer region (Q3) to neutralize the sheet (S) in a non-contact manner, and immediately downstream thereof. A configuration is described in which the conductive hair bundle (19) disposed on the surface of the sheet contacts or approaches the sheet (S).

  In Japanese Patent Application Laid-Open No. 2014-119706 as Patent Document 2, a serrated static elimination needle (21) is disposed downstream of the secondary transfer nip portion (200) and detected by a charge amount detection sensor (24). A configuration is described in which the charge on the paper (P) is neutralized by applying a variable neutralization bias to the non-contact static elimination needle (21) according to the charge amount of the paper (P).

  In JP 2009-42304 A as Patent Document 3, a transfer static elimination needle (11) is disposed on the downstream side of the transfer roller (5), and a pressure roller static elimination needle (14) is provided on the transfer static elimination needle (11). A technique for connecting and charging the pressure roller (24) with the pressure roller neutralization needle (14) using the charge neutralized from the recording material (P) with the non-contact transfer neutralization needle (11) is described. Has been.

JP, 2006-90630, A ("0034"-"0051", FIGS. 3-6) JP, 2014-119706, A ("0033"-"0036", FIG. 2, FIG. 3) JP 2009-42304 A (“0054” to “0060”, FIG. 4)

  In the present invention, compared to a configuration in which only a non-contact neutralization member is provided on the downstream side of the transfer region, or a configuration in which a neutralization member in contact with the medium is added immediately downstream of the non-contact neutralization member, It is a technical subject to reduce shortage or excessive charge removal.

In order to solve the technical problem, an image forming apparatus according to claim 1 is provided.
A transfer member for transferring the image held on the image carrier to a medium;
A first charge removal member disposed on the downstream side of the transfer member with respect to the medium conveyance direction, and for removing charge from the medium;
A second static elimination member disposed on the downstream side of the first static elimination member with respect to the conveyance direction of the medium and neutralizing the medium;
A third charge removal member disposed between the first charge removal member and the second charge removal member with respect to a medium transport direction, and having the same potential as the first charge removal member;
It is provided with.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect,
The third static elimination member composed of a nonwoven fabric having conductive fibers;
It is provided with.

According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect,
The third static elimination member is characterized in that an area of the facing surface facing the medium is smaller than an area of a surface perpendicular to the facing surface.

According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects,
A conducting member in contact with the first charge removal member and in contact with the third charge removal member;
It is provided with.

The invention according to claim 5 is the image forming apparatus according to any one of claims 1 to 3,
The third charge removal member in contact with the first charge removal member;
A conducting member for grounding the first charge eliminating member;
It is provided with.

According to a sixth aspect of the present invention, in the image forming apparatus according to the fifth aspect,
The third charge removal member which is brought into contact with the first charge removal member by folding back the connecting portion formed by cutting;
It is provided with.

According to a seventh aspect of the present invention, in the image forming apparatus according to any one of the first to sixth aspects,
A conducting member that is grounded via a preset resistance element between the first static elimination member;
It is provided with.

According to the first aspect of the present invention, compared to a configuration in which only a non-contact static elimination member is provided on the downstream side of the transfer region, or a configuration in which a static elimination member that contacts the medium is added immediately downstream of the non-contact static elimination member. Thus, it is possible to reduce insufficient or excessive charge removal of the medium after transfer.
According to invention of Claim 2, compared with the case where it does not comprise with a nonwoven fabric, manufacturing cost can be suppressed.
According to the third aspect of the present invention, the charge removal capability of the third charge removal member can be improved as compared with the case where the area of the facing surface is larger than the area of the surface perpendicular to the facing surface.

According to invention of Claim 4, the 1st static elimination member and 3rd static elimination member which contact a conduction member can be made into the same electric potential.
According to the fifth aspect of the present invention, the third charge removal member can be brought into contact with the first charge removal member so as to have the same potential.
According to the sixth aspect of the present invention, the third charge removal member can be brought into contact with the first charge removal member at the same potential by the folded connection portion.
According to the seventh aspect of the present invention, the neutralization capability of the first neutralization member and the third neutralization member can be adjusted by the resistance element.

FIG. 1 is an overall explanatory view of an image forming apparatus according to a first embodiment. FIG. 2 is an enlarged view of a main part of the toner image forming apparatus portion of FIG. FIG. 3 is an enlarged view of a transfer area portion of the first embodiment. FIG. 4 is an enlarged view of the transfer region of Example 1, and is a cross-sectional view at a position different from that in FIG. 3 in the front-rear direction. FIG. 5 is a cross-sectional view of a main part of the transfer unit according to the first embodiment. FIG. 6 is an explanatory diagram of a portion that performs electrical connection between the first static elimination member and the third static elimination member according to the first embodiment. FIG. 6A illustrates the third static elimination member according to the first embodiment. FIG. 6B is an explanatory view of a first alternative form, and FIG. 6C is an explanatory view of still another form different from FIG. 6B.

Next, specific examples of embodiments of the present invention (hereinafter referred to as examples) will be described with reference to the drawings, but the present invention is not limited to the following examples.
In order to facilitate understanding of the following description, in the drawings, the front-rear direction is the X-axis direction, the left-right direction is the Y-axis direction, the up-down direction is the Z-axis direction, and arrows X, -X, Y, -Y, The direction indicated by Z and -Z or the indicated side is defined as the front side, the rear side, the right side, the left side, the upper side, the lower side, or the front side, the rear side, the right side, the left side, the upper side, and the lower side, respectively.
In the figure, “•” in “○” means an arrow heading from the back of the page to the front, and “×” in “○” is the front of the page. It means an arrow pointing from the back to the back.
In the following description using the drawings, illustrations other than members necessary for the description are omitted as appropriate for easy understanding.

FIG. 1 is an overall explanatory view of an image forming apparatus according to a first embodiment.
In FIG. 1, a printer U as an example of the image forming apparatus according to the first exemplary embodiment includes a printer main body U1 as an example of an apparatus main body. A first discharge tray TRh as an example of a first medium discharge unit is provided on the upper surface of the printer body U1. An operation unit UI is provided on the upper surface of the right part of the printer main body U1. The operation unit UI includes a display unit (not shown). The operation unit UI is configured so that a user can perform an input operation.
A personal computer PC as an example of an image information transmission device is electrically connected to the printer U of the first embodiment.

The printer U includes a controller C as an example of a control unit. The controller C can receive electrical signals such as image information and control signals transmitted from the personal computer PC. The controller C is configured to be able to output a control signal to the operation unit UI and the electric circuit E. Further, the controller C is electrically connected to the write circuit DL.
The writing circuit DL outputs a drive signal to an exposure device ROS as an example of a writing device in accordance with the input information. The exposure machine ROS is configured to be able to output a laser beam L as an example of writing light in accordance with an input signal.

FIG. 2 is an enlarged view of a main part of the toner image forming apparatus portion of FIG.
1 and 2, a photoconductor PR as an example of an image carrier is disposed on the left side of the exposure machine ROS. The photoconductor PR of Example 1 is supported so as to be rotatable in the direction of the arrow about the rotation axis PRa. The photoconductor PR is irradiated with laser light L in the writing area Q1.
Around the photoconductor PR, along the rotational direction of the photoconductor PR, a charging roll CR as an example of a charging member, a developing device G, and a photoconductor cleaner CL as an example of a cleaner for an image carrier. Is arranged.
In the printer U according to the first exemplary embodiment, the photosensitive member PR, the charging roll CR, the developing device G, and the photosensitive member cleaner CL are integrated into a unit that can be attached and detached. That is, the photoconductor PR, the charging roll CR, the developing device G, and the photoconductor cleaner CL are configured to be detachable from the printer body U1 as a process unit U2.

A charging voltage is applied from the electric circuit E to the charging roll CR.
The developing device G includes a developing container V that accommodates toner as an example of a developer. Inside the developing container V, a developing roll Ga as an example of a developer holding body is rotatably supported. The developing roll Ga is disposed to face the photoreceptor PR in the developing area Q2.
Further, a developing voltage is applied from the power supply circuit E to the developing roll Ga. Further, augers Gb and Gc, which are examples of a developer conveying member, are rotatably supported in the developing container V.

One end of a replenishment path of a toner replenishing device TH1 as an example of a developer replenishing device fixedly supported by the printer U is connected to the developing container V. The other end of the supply path of the toner supply device TH1 is connected to a discharge port TC3 of a toner cartridge TC as an example of a developer container.
In FIG. 1, the toner cartridge TC has a cartridge main body TC1 as an example of a container main body that accommodates toner therein. A toner transport member TC2 as an example of a developer transport member is rotatably supported in the cartridge body TC1. The toner cartridge TC is configured to be detachable by being inserted into and removed from the printer U in the front-rear direction.
The photoconductor PR, the charging roll CR, the exposure machine ROS, the developing device G, and the like constitute a toner image forming apparatus that forms a toner image on the photoconductor PR.

In FIG. 1, paper feed trays TR <b> 1 to TR <b> 4 as examples of a medium storage unit are provided below the printer U. Each of the paper feed trays TR1 to TR4 accommodates a recording sheet S as an example of a medium.
In FIG. 1, rails RL1 as an example of container guide members are arranged on the left and right sides of each of the paper feed trays TR1 to TR4. The rail RL1 movably supports the left and right ends of the paper feed trays TR1 to TR4. Accordingly, the paper feed trays TR1 to TR4 are supported by the pair of left and right rails RL1 so as to be able to enter and exit in the front-rear direction.

In FIG. 1, a paper feeding device K is disposed at the upper left of each of the paper feeding trays TR1 to TR4. The paper feeding device K has a pickup roll Rp as an example of a medium take-out member. On the left side of the pick-up roll Rp, a separating roll Rs as an example of a separating member is disposed. The separating roll Rs includes a feed roll as an example of a medium conveying member and a retard roll as an example of a medium separating member.
On the left side of the sheet feeding device K, a sheet feeding path SH1 as an example of a medium transport path is disposed. The sheet feed path SH1 extends upward. A plurality of transport rolls Ra as an example of a medium transport member are arranged in the paper feed path SH1. A registration roll Rr, which is an example of a medium transport timing adjustment member, is disposed at the upper end, which is the downstream end of the sheet feed path SH1.

A manual feed tray TR0 as an example of a manual feed unit is mounted on the left side of the printer U. The right end of the manual feed tray TR0 is connected to the left end of a manual feed path SH2 as an example of a manual feed path. The right end of the manual feed path SH2 is connected to the paper feed path SH1.
In FIG. 1, a transfer roll Rt as an example of a transfer device is disposed above the registration roll Rr. The transfer roll Rt faces and contacts the photoconductor PR in the transfer region Q3. Accordingly, the transfer roll Rt according to the first exemplary embodiment rotates following the rotation of the photoconductor PR. A transfer voltage is applied from the power supply circuit E to the transfer roll Rt.

The photoreceptor cleaner CL is disposed on the downstream side of the transfer roll Rt with respect to the rotation direction of the photoreceptor PR. The photoreceptor cleaner CL includes a cleaning blade CL1 as an example of a cleaning member. The cleaning blade CL1 is formed in a plate shape. One end of the cleaning blade CL1 is in contact with the photoconductor PR.
Above the cleaning blade CL1, a cleaner container CL2 as an example of a cleaning container is disposed. The cleaning blade CL1 is supported by the cleaner container CL2. A space in which the developer can be stored is formed in the cleaner container CL2. Inside the cleaner container CL2, a collection auger CL3 as an example of a developer conveying member is rotatably supported. A recovery path CL4 as an example of a developer transport path is supported at the front end of the cleaner container CL2. The recovery path CL4 extends from the photoconductor cleaner CL to the developing device G.

In FIG. 1, a fixing device F is supported above the transfer roll Rt. The fixing device F includes a heating roll Fh as an example of a heat fixing member and a pressure roll Fp as an example of a pressure fixing member. The heating roll Fh and the pressure roll Fp are in contact with each other in the fixing region Q4. Driving is transmitted to the heating roll Fh from a driving source (not shown) to rotate. The heating roll Fh is supplied with electric power for heating a heater (not shown) from the electric circuit E.
The process unit U2, the transfer roll Rt, and the fixing device F constitute an image recording unit U2 + Rt + F that records an image on the sheet S.

Above the fixing device F, a sheet guide F1 as an example of a medium guiding portion is formed. A sheet discharge roll R1 as an example of a medium discharge member is disposed on the right side of the sheet guide F1. A medium discharge port Ha is formed on the right side of the paper discharge roll R1. A first discharge tray TRh is disposed below the medium discharge port.
In FIG. 1, a connection path SH3 as an example of a medium transport path is disposed above the fixing device F and on the left side of the paper discharge roll R1. The connection path SH3 extends to the left from the discharge port Ha.

A reversing unit U3, which is an example of a medium reversing device, is supported on the left side surface of the printer body U1 above the manual feed tray TR0. A reversing path SH4 as an example of a medium transport path is formed inside the reversing unit U3. The upper end of the inversion path SH4 is connected to the left end of the connection path SH3. The lower end of the reversing path SH4 joins the sheet feeding path SH1 on the upstream side of the registration roll Rr.
A second discharge path SH6 as an example of a medium transport path is formed above the reversing unit U3. The second discharge path SH6 has a right end connected to the connection path SH3 and branches off from the inversion path SH4. The left end of the second discharge path SH6 extends to the left side surface of the reversing unit U3. A face-up tray TRh1 as an example of a second discharge unit is supported on the left side surface of the reversing unit U3. Accordingly, the sheet S that has passed through the second discharge path SH6 is configured to be discharged to the face-up tray TRh1.

(Function of image forming apparatus)
In the printer U of the first embodiment having the above configuration, the image information transmitted from the personal computer PC is input to the controller C. The controller C converts the inputted image information into information for forming a latent image at a preset time and outputs it to the writing circuit DL. The exposure machine ROS outputs a laser beam L based on the signal received by the writing circuit DL. The controller C controls operations of the operation unit UI, the writing circuit DL, the power supply circuit E, and the like.
1 and 2, the surface of the photoreceptor PR is charged by a charging roll CR to which a charging voltage is applied. The surface of the photoconductor PR charged by the charging roll CR is exposed and scanned by the laser beam L of the exposure machine ROS at the writing position Q1 to form an electrostatic latent image. The surface of the photoconductor PR on which the electrostatic latent image is formed sequentially passes through the development area Q2 and the transfer area Q3.

In the developing area Q2, the developing roll Ga faces the photoconductor PR. The developing roll Ga rotates while holding the developer inside the developing container V on the surface. Therefore, the electrostatic latent image on the surface of the photoconductor PR is developed into a toner image as an example of a visible image by the toner image held on the surface of the developing roll Ga. The developer inside the developing container V is circulated while being stirred by the augers Gb and Gc.
When the developer inside the developing container V is consumed with the development by the developing roll Ga, the developer is supplied from the toner cartridge TC. That is, according to the consumption amount of the developer, the toner transport member TC2 is rotationally driven to transport the toner in the cartridge body TC1 to the discharge port TC3. The toner discharged from the discharge port TC3 is transported to the developing container V by a replenishment transport member (not shown) in the replenishment path of the cartridge toner replenishing device TH1.

The sheet feeding trays TR1 to TR4 accommodate sheets S on which images are recorded. The sheets S stored in the sheet feeding trays TR1 to TR4 are taken out by the pickup roll Rp of the sheet feeding device K. The sheets S taken out by the pickup roll Rp are separated one by one by the separating roll Rs. The sheet S separated by the separating roll Rs is fed to the sheet feeding path SH1. The sheet S in the sheet feeding path SH1 is conveyed toward the registration roll Rr by the conveyance roll Ra.
The sheet S fed from the manual feed tray TR0 is conveyed to the registration roll Rr through the manual feed path SH2. The sheet S conveyed to the registration roll Rr is conveyed to the transfer area Q3 by the registration roll Rr in accordance with the timing when the toner image on the surface of the photoconductor PR moves to the transfer area Q3.

In the transfer area Q3, the toner image on the surface of the photoconductor PR is transferred to the sheet S passing through the transfer area Q3 by the transfer roll Rt to which the transfer voltage is applied.
In FIG. 2, the photoreceptor PR after passing through the transfer region Q3 is cleaned by removing the toner adhering to the surface by the cleaning blade CL1. The toner removed by the cleaning blade CL1 is collected in the cleaner container CL2. The toner collected in the cleaner container CL2 is conveyed by the collection auger CL3. The toner conveyed by the collection auger CL3 is returned to the inside of the developing container V through the collection path CL4. That is, the developer collected by the photoreceptor cleaner CL is reused by the developing device G.
The photoconductor PR whose surface is cleaned by the photoconductor cleaner CL is charged again by the charging roll CR.

The sheet S on which the toner image is transferred in the transfer area Q3 is conveyed to the fixing area Q4 of the fixing device F in a state where the toner image is not fixed.
In the fixing region Q4, the sheet S is sandwiched between the heating roll Fh and the pressure roll Fp, and the toner image is heated and fixed.
The sheet S on which the toner image is fixed by the fixing device F is guided by the sheet guide F1 and conveyed to the paper discharge roll R1. When the sheet S is discharged to the first discharge tray TRh, the sheet S sent to the discharge roll R1 is discharged from the discharge port Ha to the first discharge tray TRh.

During double-sided printing, the sheet S on which an image is recorded on the first side rotates the paper discharge roll R1 in a state where the trailing end in the transport direction has passed the sheet guide F1. Accordingly, the sheet S is conveyed to the reversing path SH4 through the connection path SH3. The sheet S conveyed on the reversing path SH4 is conveyed to the registration roll Rr in a state where the front and back sides are reversed. Therefore, the image on the second side is recorded again from the registration roll Rr to the transfer area Q3.
When the sheet S is discharged to the face-up tray TRh1, the sheet S conveyed through the connection path SH3 by the reverse rotation of the discharge roll R1 is carried into the second discharge path SH6. Then, the sheet S conveyed through the second discharge path SH6 is discharged to the face-up tray TRh1.

(Description of peeling device)
FIG. 3 is an enlarged view of a transfer area portion of the first embodiment.
FIG. 4 is an enlarged view of the transfer region of Example 1, and is a cross-sectional view at a position different from that in FIG. 3 in the front-rear direction.
FIG. 5 is a cross-sectional view of a main part of the transfer unit according to the first embodiment.
1 and 3 to 5, in the printer U according to the first embodiment, a transfer unit 1 having a transfer roll Rt is detachably supported with respect to the printer main body U1. The transfer unit 1 has a housing 2 as an example of a frame. The housing 2 rotatably supports both front and rear ends of the transfer roll Rt.
The housing 2 is integrally formed with an upstream guide 3 that extends upstream in the conveyance direction of the sheet S. The upstream guide 3 guides the sheet S conveyed from the registration roll Rr to the transfer area Q3.

3 to 5, a standing wall 4 as an example of a support portion is formed in the housing 2 on the downstream side in the conveyance direction of the sheet S with respect to the transfer roll Rt.
In FIG. 3, a detack saw 6 as an example of a first static elimination member is supported on the upper surface of the standing wall 4, that is, the downstream surface in the conveyance direction of the sheet S. 3 and 6, the detack saw 6 of the first embodiment is configured by a conductive plate extending in the front-rear direction and the left-right direction. As an example, the detack saw 6 of the first embodiment is made of SUS sheet metal. The right end of the detack saw 6, that is, the end 6a on the side of the sheet S to be conveyed is formed in a sawtooth shape. Such a detack saw 6 can employ various conventionally known configurations. For example, since it is described in Patent Document 1, detailed description thereof is omitted.

3 to 5, a downstream cover 11 as an example of a protective member is supported on the housing 2 above the standing wall 4. The downstream cover 11 includes a plate-like main body portion 12 that extends in parallel with the standing wall 4 as an example of a support portion.
In FIG. 3, a cloth penetration port 12 a as an example of a first conductive passage portion is formed through the main body portion 12 in the center portion in the front-rear direction of the main body portion 12. 4 and 5, the main body portion 12 has a ground through-hole 12 b as an example of a second conductive passage portion penetrating the main body portion 12 at a position shifted in the front-rear direction from the cloth through-hole 12 a. Is formed.

A downstream guide 17 as an example of a protection member and an example of a guide member is formed on the right end of the main body 12, that is, on the side of the medium conveyance path. The downstream guide 17 is formed in a shape curved downward. As shown in FIG. 3, the downstream guide 17 according to the first embodiment is formed so as to be disposed on the right side of the right end of the detack saw 6 in a state where the downstream cover 11 is mounted on the housing 2. That is, the downstream guide 17 is configured such that the detack saw 6 is not exposed to the outside, the detack saw 6 is protected, and the sheet S can be guided on the right side of the downstream guide 17, that is, the outer surface.
In the downstream guide 17 of the first embodiment, an opening 17 a is formed at a position corresponding to the protruding end of the detack saw 6.

FIG. 6 is an explanatory diagram of a portion that performs electrical connection between the first static elimination member and the third static elimination member according to the first embodiment. FIG. 6A illustrates the third static elimination member according to the first embodiment. FIG. 6B is an explanatory view of a first alternative form, and FIG. 6C is an explanatory view of still another form different from FIG. 6B.
A neutralizing cloth 21 as an example of a third neutralizing member is supported on the upper surface of the main body 12, that is, on the downstream side in the medium conveyance direction. The static elimination cloth 21 of Example 1 is comprised with the nonwoven fabric created with the electroconductive fiber. In FIG. 3 and FIG. 6A, the neutralizing cloth 21 corresponds to the cloth penetrating part 12 a, and a notch 22 is cut into a part of the cloth, and a part of the neutralizing cloth 21 is a funnel-shaped part as an example of a connection part. 23 is formed, and the funnel-shaped portion 23 is folded back to pass through the cloth through hole 12a. Therefore, the funnel-shaped portion 23 that has passed through the cloth through hole 12 a is in contact with the detack saw 6. Therefore, the neutralizing cloth 21 and the detack saw 6 are set to have the same electric potential.

Further, in the static elimination cloth 21 of Example 1, the area of the facing surface 21a facing the sheet S is set to be smaller than the area of the surface perpendicular to the facing surface (the surface supported by the main body portion 12). In other words, a sheet-like (thin plate-like) non-woven fabric is vertically placed so as to protrude from the sheet S conveyance path.
In addition, the position of the facing surface 21a of the neutralizing cloth 21 according to the first embodiment is set on the left side of the right end of the downstream guide 17 so as not to contact the sheet S.

4 and 5, a torsion spring 26 as an example of a conducting member is disposed corresponding to the ground through hole 12 b. The torsion spring 26 has a contact portion 26a around which a wire is wound spirally. The contact portion 26 a passes through the ground through hole 12 b and contacts the detack saw 6. A spring arm 26b as an example of a connecting portion extends to the left from the contact portion 26a. At the left end of the spring arm 26b, a supported portion 26c in which a wire is wound in a spiral shape is formed. The supported portion 26c is supported in a state where a spring support protrusion 27 as an example of a conduction support portion passes through the center. The spring support protrusion 27 is formed integrally with a spring support plate 28 as an example of a conduction support portion that protrudes leftward from the housing 2.
In the torsion spring 26 according to the first embodiment, an elastic force is applied by the spring arm 26b so that the contact portion 26a contacts the detack saw 6 with a preset pressure.

A conductive contact portion 26d extending downward is formed on the supported portion 26c.
A groove portion 28 a extending from the left end to the right side is formed in the lower portion of the spring support plate 28.
In FIG. 5, a resistance support portion 29 is supported behind the spring support plate 28. In the resistance support portion 29, a groove portion 29a is formed corresponding to the groove portion 28a.
Further, behind the spring support plate 28, a ground metal plate 31 as an example of a conductive member is supported. The ground metal plate 31 is also formed with a clamp portion 31a as an example of a holding portion at a position corresponding to the groove portions 28a and 29a. The ground metal plate 31 of the first embodiment is made of a conductive metal. The ground metal plate 31 is grounded, that is, so-called grounded through a conduction portion (not shown).

A resistance element 32 is supported in each of the groove portions 28a and 29a and the clamp portion 31a. The resistance element 32 includes a resistance main body 32a at the center in the front-rear direction and connection portions 32b and 32c extending from the resistance main body 32a to the front and rear sides. In the first embodiment, as an example, a resistor of 100 MΩ is used as the resistor main body 32a.
The front connection portion 32b is supported so as to be sandwiched between the clamp portions 31a. Therefore, the connection part 32b is connected to the ground.
The rear connection portion 32c extends rearward through the grooves 28a and 29a. And the conduction contact part 26d contacts and is supported by the connection part 32c. The torsion spring 26 is configured such that an elastic force is exerted by the conductive contact portion 26d pushing the connection portion 32c to the right. Therefore, the conduction contact portion 26d is configured to fix and support the connection portion 32c between the groove portions 28a and 29a and to make an electrical reliable contact.

  In FIG. 3, a sheet guide 36 as an example of a medium guide member is disposed downstream of the transfer unit 1 in the conveyance direction of the sheet S. A neutralization sheet 37 as an example of a second neutralization member is supported on the surface of the sheet guide 36 on the conveyance path side. The static elimination sheet 37 of Example 1 is comprised with the nonwoven fabric created with the electroconductive fiber similarly to the static elimination cloth 21. FIG. As for the static elimination sheet 37, the sheet-like nonwoven fabric is arrange | positioned along the conveyance path of the sheet | seat S. FIG. In addition, the static elimination sheet 37 of Example 1 is arrange | positioned in the position which becomes non-contact with respect to the sheet | seat S conveyed. Moreover, the static elimination sheet 37 of Example 1 is not grounded and is electrically in a so-called float state.

(Operation of Example 1)
In the printer U according to the first embodiment having the above-described configuration, the sheet S after transfer is neutralized by the detack saw 6, the neutralizing cloth 21, and the neutralizing sheet 37 disposed on the back side before being conveyed to the fixing region Q4. Is done.
When the voltage applied to the static elimination needle is controlled as in the configurations described in Patent Documents 2 and 3, there is a difference between the voltage detection position and the static elimination needle position. Therefore, the voltage is not appropriate for the amount of charged toner of the unfixed image on the sheet surface, and there are cases where charge removal is insufficient or excessive charge removal. If the charge removal is insufficient, the sheet guide up to the fixing area Q4 may be electrostatically attracted. When the sheet is adsorbed by the paper guide, a paper jam may occur, or when only the right side of the sheet conveyance direction is adsorbed, the sheet enters the fixing device F in a so-called skewed state, and paper wrinkles are generated. There is a problem to do. Paper wrinkles are particularly likely to occur when the sheet S has low rigidity, such as when the direction of paper fibers (horizontal line, vertical line) is vertical, or when vertical lines are likely to enter the sheet S. In addition, when the charge is excessively removed, the ability to electrically hold the charged toner of the unfixed image is weakened. Therefore, unfixed toner can easily move, resulting in poor image quality.

Moreover, in the structure of patent document 2, 3, the structure which applies a voltage to the sensor which detects a voltage, or a static elimination needle is needed, and there also exists a problem which manufacturing cost tends to raise.
Furthermore, if a static elimination member that contacts the sheet is used as described in Patent Document 1, excessive static elimination tends to occur. As a result, image quality defects may occur due to excessive charge removal. In particular, when the amount of developer is large or stacked, as in the case of an image forming apparatus for high-density images or multicolor printing, image quality defects such as color loss may occur when excessive charge removal occurs. It tends to occur.

On the other hand, in Example 1, the sheet S that has passed through the transfer region Q3 is neutralized by non-contact discharge with the grounded detack saw 6. Therefore, compared with the case where a voltage is applied like patent document 2, 3, excessive static elimination is reduced. In particular, in the first embodiment, the detack saw 6 is not directly grounded but is grounded via the resistance element 32. When the voltage is directly grounded, that is, 0 V, excessive static elimination may occur. However, in Example 1, excessive static elimination is further suppressed by the resistance value of the resistance element 32.
In addition, when the detack saw 6 is not sufficient for neutralizing the sheet S, the neutralization cloth 21 on the downstream side performs neutralization. Therefore, the shortage of static elimination is reduced compared to the case where the static elimination cloth 21 is not provided. In addition, when the charge removal is sufficient with the detack saw 6, the discharge hardly occurs between the detack saw 6 and the charge removal cloth 21 having the same potential. Therefore, excessive static elimination with the static elimination cloth 21 is also reduced.

Further, when the static elimination cloth 21 is insufficient in static elimination, the static elimination sheet 37 on the downstream side performs static elimination. The neutralization sheet 37 is not grounded, and its neutralization capability is lower than that of the detack saw 6 or the neutralization cloth 21. Therefore, compared with the case where the static elimination sheet 37 is earth | grounded, the excessive static elimination in the static elimination sheet 37 is also reduced.
Therefore, in the printer U according to the first embodiment, when the voltage is supplied to the non-contact static elimination needle as in the configurations described in Patent Documents 2 and 3, or the configuration including the static eliminating member that is in contact as described in Patent Document 1 Compared to the above, insufficient charge removal or excessive charge removal of the sheet S after transfer is reduced.

Moreover, the static elimination cloth 21 of Example 1 is comprised with the nonwoven fabric instead of sheet metal like the detack saw 6. FIG. Therefore, it is easy to suppress manufacturing costs.
Furthermore, the static elimination cloth 21 of Example 1 is placed vertically. Therefore, compared with the case where the sheet is placed horizontally like the charge removal sheet 37, the facing surface 21a is sharp and discharge is likely to occur. Therefore, the static elimination performance is higher than the horizontal installation.

(Example of change)
As mentioned above, although the Example of this invention was explained in full detail, this invention is not limited to the said Example, A various change is made in the range of the summary of this invention described in the claim. Is possible. Modification examples (H01) to (H07) of the present invention are exemplified below.
(H01) In the above-described embodiment, the printer as an example of the image forming apparatus is illustrated. However, the present invention is not limited to this, and the present invention can be applied to an image forming apparatus such as a copying machine or a FAX. Further, the present invention is not limited to a single color image forming apparatus, and can be applied to a multicolor image forming apparatus. Therefore, although the photoconductor PR as an example of the image carrier is illustrated, the present invention is not limited to this. For example, the present invention can be applied to an image forming apparatus having an intermediate transfer belt, an intermediate transfer drum, or the like as an example of an image carrier.

(H02) In the above-described embodiment, the configuration in which the static elimination cloth 21 is formed of a nonwoven fabric is illustrated, but the present invention is not limited thereto. For example, it is also possible to use a woven fabric, a conductive resin, or a metal similar to the detack saw 6.
(H03) In the above-described embodiments, the specific numerical values illustrated can be changed as appropriate according to design, specifications, and the like. Therefore, any resistance value of the resistance element 32 can be used according to the charge removal performance.
(H04) In the above-described embodiment, it is desirable that the neutralizing cloth 21 be placed vertically, but the length and width of the facing surface 21a of the neutralizing cloth 21 can be appropriately changed according to the necessary neutralizing capability.

(H05) In the above-described embodiment, the configuration in which the antistatic cloth 21 is brought into contact with the detack saw 6 and the torsion spring 26 is brought into contact with the detack saw 6 is exemplified, but the present invention is not limited thereto. As shown in FIG. 6B, it is possible to adopt a configuration in which the static elimination cloth 21 is directly in contact with the torsion spring 26 without being in contact with the detack saw 6. 6C, the torsion spring 26 may be brought into contact with the neutralization cloth 21 instead of the detack saw 6, and the detack saw 6 may be in contact with the torsion spring 26 indirectly via the neutralization cloth 21. is there. Therefore, it is possible to adopt a configuration in which the detack saw 6 and the neutralizing cloth 21 are brought into direct contact to make them electrically the same potential, or a configuration in which they are made to have the same potential through members such as the torsion spring 26.

(H06) In the above embodiment, it is desirable to use the torsion spring 26 to apply an elastic force to ensure conduction with the detack saw 6, but this is not limitative. It is possible to adopt any form capable of establishing conduction with the detack saw 6 without applying an elastic force. For example, it is possible to fasten with a metal screw or use a conductive tape such as a conductive adhesive or aluminum tape. In addition, any change can be made according to design, specifications, and the like, such as providing a plurality of conductive members between the torsion spring 26 and the ground metal plate 31.
(H07) In the above-described embodiment, it is desirable to provide the resistance element 32, but it is also possible to adopt a configuration in which the resistance element 32 is not provided depending on the required static elimination capability.

6 ... 1st static elimination member,
21 ... Third static elimination member,
21a ... opposite surface,
22 ... notches,
23 ... connection part,
26: Conducting member,
32 ... resistance element,
37 ... Second static elimination member,
PR: Image carrier,
Rt: transfer member,
S ... medium
U: Image forming apparatus.

Claims (7)

A transfer member for transferring the image held on the image carrier to a medium;
A first charge removal member disposed on the downstream side of the transfer member with respect to the medium conveyance direction, and for removing charge from the medium;
A second static elimination member disposed on the downstream side of the first static elimination member with respect to the conveyance direction of the medium and neutralizing the medium;
A third charge removal member disposed between the first charge removal member and the second charge removal member with respect to a medium transport direction, and having the same potential as the first charge removal member;
An image forming apparatus comprising: The third static elimination member composed of a nonwoven fabric having conductive fibers;
The image forming apparatus according to claim 1, further comprising: The image forming apparatus according to claim 1, wherein the third static elimination member has an area of a facing surface facing the medium that is smaller than an area of a surface perpendicular to the facing surface. A conducting member in contact with the first charge removal member and in contact with the third charge removal member;
The image forming apparatus according to claim 1, further comprising: The third charge removal member in contact with the first charge removal member;
A conducting member for grounding the first charge eliminating member;
The image forming apparatus according to claim 1, further comprising: The third charge removal member which is brought into contact with the first charge removal member by folding back the connecting portion formed by cutting;
The image forming apparatus according to claim 5, further comprising: A conducting member that is grounded via a preset resistance element between the first static elimination member;
The image forming apparatus according to claim 1, further comprising:

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