JP5471762B2 - Transfer device and image forming apparatus - Google Patents

Description

  The present invention relates to a transfer device that transfers toner on an image carrier onto a sheet and an image forming apparatus including the transfer device.

  In recent years, low-melting point offset preventive agent (tentatively referred to as wax) is contained in a large amount of toner to create a vivid color image or reduce the temperature of the heating roller or the like to reduce the power consumption of the image forming apparatus. I am trying. Therefore, when the paper is discharged from the fixing device in the image forming apparatus, the toner image on the paper is covered with melted wax, and various members located on the downstream side of the fixing device are removed from the toner image on the paper. Gradually contaminated with transferred wax. Then, the contaminated wax from various members is transferred onto the paper.

  During double-sided recording, a large wax lump reaches the transfer device through a single-side printed paper surface, and there is a cleaning problem that residual toner on the transfer member cannot be removed due to mixing of the wax lump. That is, when a large lump of wax is transferred onto a roller-shaped or belt-shaped transfer member and finally captured by a blade that removes residual toner on the transfer member, the portion of the wax where the wax is captured has a cleaning blade. The tip is curled and the remaining toner cannot be cleaned at all.

  On the other hand, Patent Documents 1 and 2 disclose a cleaning apparatus having a foreign matter removing member that removes foreign matter mixed in through a sheet from a cleaning target.

  The cleaning device described in Patent Document 1 is provided with a foreign matter removing member composed of a brush roller that rotates upstream in the moving direction of the intermediate transfer member with respect to the cleaning blade, and also collects toner at the same time as paper dust removal. This makes it possible to reduce the load on the cleaning blade and extend the life of the cleaning blade.

  Further, in the cleaning device described in Patent Document 2, as in Patent Document 1, a foreign matter removing member of the brush roller is disposed on the upstream side with respect to the cleaning blade to prevent craning failure due to paper dust. Further, a roller-like application brush for applying a lubricant on the intermediate transfer member is provided downstream of the cleaning blade to prevent a craning failure due to a change in the friction coefficient on the intermediate transfer member.

JP 2003-215938 A JP 2007-121965 A

  However, the cleaning devices described in Patent Documents 1 and 2 use a brush roller as a foreign matter removing member and cannot effectively remove wax. In addition, if a brush roller mechanism (high density brush, high speed rotation, large size) that can prevent poor cleaning due to wax lumps is used, the lubricant applied on the intermediate transfer member will be lost excessively, and the cleaning blade may become swollen. Create new problems.

  The present invention provides a cleaning device and an image forming apparatus that can prevent a defective cleaning due to a lump of wax on a transfer member and blade curl due to a decrease in lubricity on the transfer member.

  Said subject is achieved by implement | achieving the following invention.

1. The paper transfer unit formed with the image carrier rotates while abutting against the surface opposite to the transfer surface of the paper, and the toner image developed with the toner containing the wax on the image carrier is transferred to the paper. A transfer member;
A first blade that presses against the transfer member with a first pressure contact strength to remove toner remaining on the transfer member;
A wax disposed on the upstream side in the rotation direction of the transfer member with respect to the first blade, and pressed against the transfer member with a second pressure contact strength smaller than the first pressure contact strength. A second blade for removing lumps;
I have a,
The transfer apparatus according to claim 2, wherein the second pressure contact strength is a strength within a range in which the toner remaining on the transfer member is not removed by the second blade and passes through .

2 . 2. The transfer apparatus according to 1 above, wherein the second pressure contact strength is in a range in which a wax lump larger than an average particle diameter of toner can be removed by the second blade.

3 . 3. The transfer apparatus according to claim 1 or 2 , further comprising a lubricant application unit that is located downstream of the first blade in the rotation direction of the transfer member and applies the lubricant evenly onto the transfer member. .

4 . When the length of the first blade in the width direction orthogonal to the rotation direction is W1, the length of the second blade in the width direction is W2, and the length of the lubricant application means is W3, W1 , transfer apparatus according to 3, wherein the following relationship is satisfied in the W2 and W3.
W3> W 1> W 2
5 . 5. The transfer apparatus according to any one of 1 to 4 ,
A fixing device for fixing a toner image formed on a sheet;
A double-sided conveyance path for reversing a sheet processed with the fixing device and having a toner image formed on the surface thereof, and conveying it to the sheet transfer unit;
An image forming apparatus comprising:

  The present invention makes it possible to provide a transfer device and an image forming apparatus that can prevent a cleaning failure due to the inclusion of a wax lump.

1 is a configuration diagram showing an image forming apparatus using a cleaning device according to the present invention. FIG. 2 is an enlarged cross-sectional view showing an outline of a secondary transfer apparatus 90 according to the first embodiment of the present invention. FIG. 4 is a schematic diagram showing the transition of toner and wax lump W transferred on the transfer belt 91. These are the expanded sectional views which show the outline | summary of the secondary transfer apparatus 90 which concerns on 2nd Embodiment of this invention. FIG. 4 is a schematic diagram showing the transition of the toner and wax lump W transferred onto the transfer belt 91 and the lubricant applied by the lubricant applying means 95. These are schematic views showing the positional relationship in the width direction perpendicular to the rotation direction of the transfer belt 91 with respect to the main members of the secondary transfer device. These are the schematic diagrams which show the contact conditions (an example) of the 1st braid | blade 94, the 2nd braid | blade 93, and the 3rd braid | blade 955 in 1st and 2nd embodiment which concern on this invention.

  Embodiments of the present invention will be described below. The description in this column does not limit the technical scope of the claims or the meaning of terms.

<Electrophotographic image forming apparatus>
FIG. 1 is a block diagram showing an image forming apparatus A provided with a cleaning device according to the present invention.

  The image forming apparatus A includes an image reading apparatus B placed on the upper part of the apparatus main body.

  The image forming apparatus A is called a tandem type color image forming apparatus, and has an image forming unit having a plurality of sets of image forming units 10Y, 10M, 10C, and 10K and an intermediate transfer member 6 as an image carrier according to the present invention. 100, a sheet feeding / conveying unit 20, a fixing device 30, and the like.

  Above the image forming apparatus A, an image reading apparatus B including an automatic document feeder DF and an original image scanning exposure apparatus SC is installed. A document d placed on the document table of the automatic document feeder DF is transported by a transport means, and an image on one or both sides of the document is scanned and exposed by the optical system of the document image scanning exposure device SC. Is read.

  The signal formed by photoelectric conversion by the line image sensor CCD is subjected to analog processing, A / D conversion, shading correction, image compression processing, and the like in the image processing unit, and then exposure means 3Y, 3M, 3C, 3K. Sent to.

  In the image forming unit 10Y that forms a yellow (Y) toner image, a charging unit 2Y, an exposure unit 3Y, a developing unit 4Y, and a cleaning unit 5Y are arranged around the photoreceptor 1Y. In the image forming unit 10M that forms a magenta (M) toner image, a charging unit 2M, an exposing unit 3M, a developing unit 4M, and a cleaning unit 5M are arranged around the photoreceptor 1M. In the image forming unit 10C for forming a cyan (C) toner image, a charging unit 2C, an exposure unit 3C, a developing unit 4C, and a cleaning unit 5C are arranged around the photoreceptor 1C. In the image forming unit 10K that forms a black (K) toner image, a charging unit 2K, an exposure unit 3K, a developing unit 4K, and a cleaning unit 5K are arranged around the photoreceptor 1K. The charging unit 2Y and the exposure unit 3Y, the charging unit 2M and the exposure unit 3M, the charging unit 2C and the exposure unit 3C, and the charging unit 2K and the exposure unit 3K constitute a latent image forming unit.

  The developing units 4Y, 4M, 4C, and 4K include a two-component developer including yellow (Y), magenta (M), cyan (C), and black (K) toner having a small particle diameter and a carrier.

  The intermediate transfer member 6 is wound around a plurality of rollers and is rotatably supported by a driving unit (not shown).

  The fixing device 30 fixes an unfixed toner image on the paper P by heating and pressing at a fixing nip portion formed between a heated fixing member (also referred to as a fixing belt) 31 and a pressure belt 32. .

  The toner used in the above embodiment contains 10 parts by mass of an offset preventive agent with respect to 100 parts by mass of the resin.

  The anti-offset agent has a low molecular weight and a low melting point compared to the main resin of the toner, so that it becomes a molten state unlike the main resin that remains in a viscoelastic state when passing through the fixing nip of the fixing device. It expands so as to cover the surface and occupies the interface between the surface layer of the fixing member 31 and the toner layer, and the releasability of the toner layer with respect to the surface layer of the fixing member 31 can be dramatically improved.

  Here, a low molecular weight polypropylene wax is used as an anti-offset agent (hereinafter referred to as wax), but the following waxes can be used.

  Specific examples include olefin waxes such as low molecular weight polyethylene and copolymer polyethylene, paraffin wax; ester waxes having a long-chain aliphatic group such as behenic acid ester, montanic acid ester, and stearic acid ester. .

  By the primary transfer units 7Y, 7M, 7C, and 7K, the toner images of the respective colors formed by the image forming units 10Y, 10M, 10C, and 10K are sequentially transferred onto the intermediate transfer body 6 as the image carrier according to the present invention. A toner image composed of each color toner is formed on the intermediate transfer body 6 (primary transfer).

  On the other hand, the paper P is fed from the paper feeding cassette 21 of the paper feeding / conveying section 20 by the paper feeding means 22 and conveyed to the secondary transfer device 90 through the paper feeding rollers 23, 24, 25, 26, the registration rollers 27, and the like. The The toner image formed on the intermediate transfer member 6 by the secondary transfer device 90 is transferred onto the paper P.

  The sheet P on which the toner image has been transferred is separated from the intermediate transfer member 6 by curvature separation and conveyed to the fixing device 30. The toner image on the paper P is heated and pressed by the fixing device 30 and fixed on the paper P. Thereafter, the paper P is sandwiched between the paper discharge rollers 24 and placed on a paper discharge tray 29 outside the apparatus.

  On the other hand, the intermediate transfer member 6 reaches the cleaning unit 8 after the toner image is transferred onto the paper P by the secondary transfer device 90, and the residual toner on the intermediate transfer member 6 is removed by the cleaning unit 8. Are cleaned so that image formation is possible again.

  In the case of reversely discharging the fixed paper P, the paper P passes through a conveyance path on the right side of the branch plate 28A disposed between the fixing device 30 and the paper discharge roller 28, and the first conveyance below. After being transported to the path Sa, it is transported in the reverse direction, passes through the second transport path Sb on the left side of the branch plate 28B, and is discharged out of the apparatus by the paper discharge roller 28.

  When images are formed on both sides of the paper P, the paper P with the toner image formed on the surface is processed by the fixing device 90, and then the first transport path Sa, the fourth transport path Sd, and the third transport path. The paper is transferred to the paper transfer portion Pt via the double-sided conveyance path S constituted by Sc. Then, the sheet P is transported reversely while passing through the double-sided transport path SS. This will be described in detail below.

  After fixing the image formed on the first surface of the paper P, the paper P is introduced into the first transport path Sa, and further into the fourth transport path Sd below the branch plate 28B, and then transported in the reverse direction and turned upside down. . The sheet P that is turned upside down passes through the conveyance path on the right side of the branch plate 28B, is conveyed to the third conveyance path Sc, detours upward, and is conveyed to the sheet transfer portion Pt by the sheet feeding roller 26.

  Then, the color image on the intermediate transfer body 6 is transferred to the second surface of the paper P in the paper transfer portion Pt, and a color image is formed on the second surface of the paper P. Further, the paper P is heated and fixed by the fixing device 30 and is discharged out of the device by the paper discharge roller 28.

  In the embodiment of the present invention, toner to which wax is added is used, and a member such as a roller constituting a conveyance path from the first conveyance path Sa on the downstream side of the fixing device 30 to the fourth conveyance path Sd is formed on the sheet P. Contaminated by transfer of wax from Wax contamination becomes more severe as it is closer to the fixing device 30, and the state of the first transport path Sa and the second transport path Sb is more severe than the third transport path Sc and the fourth transport path Sd. In particular, a member such as a roller disposed in the double-sided conveyance path S near the fixing device is more severely contaminated.

[Secondary transfer device]
FIG. 2 is an enlarged sectional view showing an outline of the secondary transfer apparatus 90 according to the first embodiment of the present invention.

  The secondary transfer device 90 includes a transfer belt 91, a first blade 94, and a second blade 93 as transfer members.

  The transfer belt 91 is suspended by a driving roller 92A and a transfer roller 92B and is rotated in the direction of arrow a. The transfer belt 91 is rotated in the direction of arrow a while being in contact with the back surface of the paper P. It is in contact with the intermediate transfer member 6. The transfer roller 92B is urged against the support roller 61 that suspends the intermediate transfer member 6 at the paper transfer portion Pt, brings the transfer belt 91 into contact with the intermediate transfer member 6, and is further connected to a high voltage power source E1 to apply a bias voltage Vt. It is possible. At least when the paper P passes through the paper transfer portion Pt, a bias voltage Vt is output, and the toner image on the intermediate transfer body 6 is transferred onto the paper P.

  The first blade 94 is disposed on the downstream side (position indicated by Pc in the figure) in the moving direction of the transfer belt 91 with respect to the sheet transfer portion Pt, and scrapes the toner remaining on the transfer belt 91 at its tip. It is to be collected.

  The first blade 94 is made of urethane rubber and is heat-welded to the blade support member 94a. The blade support member 94a is rotatably supported by a support shaft 94b fixed to the casing of the secondary transfer device 90. A compression spring 94d is biased to the other end 94c of the blade support member 94a, and the other end 94c of the blade support member 94a is biased in the direction of arrow c.

  As a result, the first blade 94 is pressed against the transfer belt with a predetermined strength F1. Here, F1 = 40 N / m, and F1 is a normal direction pressing force (N) per unit meter (m) in the width direction of the first blade 94. The normal direction pressing force is a normal direction component of the pressing force against the rotating transfer belt 91.

  The second blade 93 is disposed on the upstream side (position indicated by Pw in the drawing) of the first blade 94 in the moving direction of the transfer belt 91, and removes toner remaining on the transfer belt 91, thereby removing the toner from the paper P. The second pressure strength F2 at which the second blade 93 presses against the transfer belt 91 is intended to remove the wax lump W transferred on the transfer belt 91 from the transfer belt 91. The first blade 94 has a second pressure contact strength F2. Is set to be smaller than the first pressure contact strength F 1 that is pressed against the transfer belt 91.

  The second blade 93 is made of a polyethylene terephthalanol resin sheet having a thickness of 0.1 mm, and the leading end of the second blade 93 is positioned by a driven roller that is in contact with the inner peripheral surface of the transfer belt 91. The other end of the second blade 93 is thermally welded to the support member 93a. The second blade 93 bends, and its tip has a nip length Ln that is substantially parallel to the transfer belt 91 in the rotational direction of the transfer belt 91.

  The nip length Ln corresponding to the pressure contact strength F2 of the second blade 93 can be appropriately set by adjusting the fixing position of the support member 93a up and down as indicated by the arrow f. Here, Ln = 1 mm.

  By adjusting the fixing position of the support member 93a, when the paper P is not passed, the majority of the toner half of the toner transferred from the intermediate transfer body 6 to the transfer belt 91 slips through and a large wax lump W larger than the toner particle size is removed. By setting the pressure contact strength F2 of the second blade 93 so that it can be removed, a secondary transfer apparatus having the following advantages can be realized.

  The toner has characteristics as a solid lubricant. When the second pressure contact strength F2 is within the above range, the wax related to the cleaning failure can be removed, and at the tip of the first blade 94, a predetermined amount or more can be obtained. The toner is always retained to prevent the first blade 94 from curling. In addition, since the lubricity on the transfer belt 91 is maintained for a long time, the first blade 94 and the transfer belt 91 can be extended in life, and the secondary transfer device 90 itself can be extended in life.

  Next, how the appropriate setting of the pressure contact strength F2 of the second blade 93 is obtained will be described.

  The forced live-action test is continuously performed for 1000 sheets while changing the fixing position of the support member 93a and forcibly generating a state in which wax blocks W of various sizes are applied onto the paper P from the conveyance path. As a result, the “acceptable range at the fixed position of the support member 93 a” in which both the cleaning failure due to the wax block and the blade curl due to toner depletion do not occur in the first blade 94 is acquired.

  The “allowable range at the fixing position of the support member 93a” experimentally obtained as described above corresponds to the “allowable range of the pressure contact strength F2 of the second blade 93”, and the appropriate pressure contact strength F2 Settings can be realized.

  FIG. 3 is a schematic diagram showing the transition of the toner and wax mass W transferred onto the transfer belt 91. The Δ mark is a wax lump W larger than the toner particles, and the ● mark is toner.

  When a large wax lump W such as a triangle mark is captured at the tip of the first blade 94, the wax lump W sequentially takes in the toner staying at the tip of the blade and the newly captured toner, and consists of a large number of toners. It gradually grows as a lump of large toner groups. Then, it is presumed that the leading edge of the first blade 94 is curled by the toner cluster and a cleaning failure occurs.

  As shown in the drawing, the toner and the wax lump W are transferred from the sheet P conveyed in the direction of the arrow g to the transfer belt 91 that rotates in the direction of the arrow a at the sheet transfer portion Pt, and the second blade 93 at the position Pw. A lump of wax W larger than the toner is selectively removed from the transfer belt 91 as indicated by an arrow h. On the other hand, the majority of the toner is not removed by the second blade 93 but is captured by the first blade 94 and is retained at the tip of the first blade 94, and the toner overflowing from the stay at the tip is lowered and collected. Is done.

  Of the wax transferred to the transfer belt 91 at the paper transfer portion Pt, most of the wax having a particle diameter equal to or smaller than the toner particle size is not removed by the second blade 93 but is captured by the first blade 94. The toner does not grow into a large toner cluster, but is collected as a small toner cluster by descending from the contact portion of the first blade 94 or is thinly coated on the transfer belt 91.

  It is presumed that there is no problem even if the wax having a particle diameter equal to or smaller than the toner particle diameter is not removed by the second blade 93.

  FIG. 4 is an enlarged cross-sectional view showing an outline of the secondary transfer apparatus 90 according to the second embodiment of the present invention.

  Unlike the first embodiment, the secondary transfer device 90 is provided with a lubricant application means 95 on the downstream side of the first blade 94 in the moving direction of the transfer belt 91.

  The lubricant application unit 95 applies the lubricant K on the transfer belt 91 and has a lubricant application roller 951 and a third blade 955.

  The lubricant application roller 951 is rotatably attached to a support member 954 fixed to the casing of the secondary transfer device 90. The tip of the lubricant application roller 951 abuts on the transfer belt 91 at a position indicated by Pk in the moving direction of the transfer belt 91 and is rotated in the direction of arrow b by a drive mechanism (not shown). The surface is coated with a lubricant K, and the lubricant K is constantly supplied onto the transfer belt 91.

The lubricant application roller has an outer diameter of 18 mm, in which nylon having a diameter of 6 denier (density 120 kF / (inch) ² , resistance value 1 × 10 ¹¹ to 1 × 10 ¹² Ω) is implanted around a core metal having a diameter of 10 mm. This is a brush roller.

  The lubricant block 952 is a quadrangular prism solid made of the lubricant K, and one surface of the quadrangular prism is brought into contact with the lubricant application roller 951 by the urging force of the compression spring 953 as shown in the figure. The lubricant K is applied onto the lubricant application roller 951 with the above-described configuration.

  Here, a fatty acid metal salt is used as the lubricant K. Examples of the fatty acid metal salt used here include zinc stearate, calcium stearate, and aluminum stearate, but the fatty acid metal salt used in the present invention is not limited thereto.

  The third blade 955 is disposed on the downstream side (position indicated by Pm in the drawing) of the lubricant application roller 951 in the moving direction of the transfer belt 91, and smoothes the excess lubricant K applied on the transfer belt 91. The surface is coated as a thin layer of lubricant K. Therefore, the third blade 955 is in contact with the rotating transfer belt 91 by a trail method in which the blade tip does not penetrate.

  By providing the lubricant applying means 95, it is not necessary to consider the problem that the lubricity between the transfer belt 91 and the first blade 94 due to the depletion of the toner staying at the tip of the first blade 94 is impaired. However, it is necessary to maintain the lubricant K on the transfer belt 91 at an appropriate thickness. For example, if the lubricant K is too thick, image problems such as transfer unevenness and image blur will occur.

  Accordingly, the third blade 955 is disposed on the downstream side (indicated by Pm) in the rotation direction of the transfer belt 91 with respect to the lubricant application roller 951, and the third blade 955 is placed on the transfer belt 91 by the lubricant application roller 951. The applied excess lubricant K is thinly stretched and leveled.

  The third blade 955 is made of urethane rubber resin (hardness 74 °, free length 6 mm) with a thickness of 1.6 mm, the tip abuts against the transfer belt 91, and the other end is a support fixed to the support member 954. It is heat welded to the plate 956.

  FIG. 5 is a schematic diagram showing the transition of the toner and wax mass W transferred onto the transfer belt 91 and the lubricant K applied by the lubricant applying means 95. A square indicates the lubricant K applied on the transfer belt 91 by the lubricant application roller 951 and Pk.

  The lubricant K on the transfer belt 91 is thinly coated with the third blade 955 to such an extent that uneven transfer and image blur do not occur. The lubricant K coated on the transfer belt 91 is removed together by the first blade 94, and the lubricant application means 95 is supplemented with an appropriate amount of the lubricant K so as to compensate for this. The stability and durability of the secondary transfer device are maintained by the balance between the application and removal of the lubricant K by the first blade 94 and the lubricant application means 95.

  Therefore, in order to prevent cleaning failure due to the large lump of wax W transferred to the transfer belt 91 at the paper transfer portion Pt, the second blade 93 is located upstream of the first blade 94 in the moving direction of the transfer belt 91 (Pw in the drawing). The pressure contact strength F2 at which the second blade 93 presses against the transfer belt 91 is within a range where the balance between the application and removal of the lubricant by the first blade 94 and the lubricant application means 95 is not lost. Must be set.

  Next, an experimental method for easily obtaining an appropriate setting of the pressure contact strength F2 of the second blade 93 in the second embodiment of the present invention will be described.

  A forcible operation test is performed in which the secondary transfer device 90 is continuously idled for 1000 sheets continuously by changing the fixing position of the support member 93a, and the first blade 94 is curled due to a decrease in lubricity on the transfer belt 91. No “first permissible range at the fixed position of the support member 93a” is obtained. Further, the position where the support member 93a is fixed is changed, and a forced live-action test of 1000 continuous sheets is executed while forcibly generating a state in which wax blocks W of various sizes are applied onto the paper P from the conveyance path. Thus, the “second allowable range at the fixed position of the support member 93a” is obtained, in which the cleaning failure due to the wax block does not occur in the first blade 94.

  The “allowable range at the fixed position of the support member 93a” including both the “first allowable range” and the “second allowable range” obtained experimentally as described above is acquired.

  The “allowable range at the fixing position of the support member 93a” experimentally obtained as described above corresponds to the “allowable range of the pressure contact strength F2 of the second blade 93”, and the appropriate pressure contact strength F2 Settings can be realized.

  That is, the secondary transfer device 90 of FIG. 4 always maintains the lubricant K coated on the transfer belt 91 in a range where the first blade 94 does not sag even when toner is not transferred at all for a long time. .

  In the second embodiment of the present invention, the lubricity on the transfer belt 91 is always stably maintained even when a situation where no toner as a solid lubricant exists on the transfer belt 91 continues for a long time. On the other hand, the large wax lump W transferred onto the transfer belt 91 through the paper P is reliably removed from the transfer belt 91, so that it is possible to prevent the cleaning defect and blade curl due to the wax lump W. In addition, a secondary transfer device and an image forming apparatus that are excellent in extending the life of the first blade 94 and the transfer belt 91 can be realized.

  FIG. 6 is a schematic diagram showing the positional relationship in the width direction perpendicular to the rotation direction of the transfer belt 91 with respect to the main members of the secondary transfer device. Wt is the length of the transfer belt 91 in the width direction. W1 is the length in the width direction of the first blade 94, and is equal to the maximum length in the width direction of the paper P passing through the paper transfer portion Pt. W2 is the length of the second blade 93 in the width direction. W3 is the length of the lubricant application roller in the width direction, and the lubricant is applied to the transfer belt 91 over the width of W3. W4 is the length of the third blade 955 in the width direction.

  Wt, W1, W2, W3, and W4 are substantially evenly disposed with respect to the center Lc in the width direction of the transfer belt 91, and the following relationship is preferable.

Wt>W4>W3> W 1 > W 2
In particular, since the relationship of W4> W3 is satisfied and the position in the width direction of the lubricant application roller 951 is always inside the position in the width direction of the third blade 955, the lubricant K applied by the lubricant application roller 951 is in the third blade 955. It is possible to level evenly.

Also, W3> by relation W 1, since the width direction position of the first blade 94 is located always inside the widthwise position of the lubricant coating roller 951, the first blade 94 is also blade curling is reliably prevented in the side edge Is done.

Further, since the position in the width direction of the second blade 93 is always inside the position in the width direction of the first blade 94 due to the relationship of W 1 > W 2 , the toner and the lubricant K are surely attached to the end portion of the first blade 94. Thus, blade curling that occurs at the side end of the first blade 94 can be more reliably prevented.

  FIG. 7 is a schematic diagram showing contact conditions (one example) of the first blade 94, the second blade 93, and the third blade 955 in the first and second embodiments according to the present invention.

  L1 is the length of the free end of the first blade 94, which is 9 mm. L2 is the length of the free end of the second blade 93 and is 7 mm. L3 is the length of the free end of the third blade 955 and is 6 mm.

  Α is the contact angle of the second blade 93 and is 21 °. β is the contact angle of the first blade 94 and is 28 °. θ is the contact angle of the third blade 955 and is 52 °.

  The embodiment of the present invention is an image forming apparatus using an intermediate transfer member. However, the present invention is not limited to this, and the present invention forms an image on a photosensitive member and transfers the image onto a sheet. It is also applicable to the device.

6 Intermediate transfer member (image carrier)
90 Secondary transfer device (transfer device)
91 Transfer belt (transfer member)
93 2nd blade 94 1st blade 95 Lubricant application means 955 3rd blade P Paper A Image forming device K Lubricant W Wax lump Pt Paper transfer section

Claims (5)

The paper transfer unit formed with the image carrier rotates while abutting against the surface opposite to the transfer surface of the paper, and the toner image developed with the toner containing the wax on the image carrier is transferred to the paper. A transfer member;
A first blade that presses against the transfer member with a first pressure contact strength to remove toner remaining on the transfer member;
A wax disposed on the upstream side in the rotation direction of the transfer member with respect to the first blade, and pressed against the transfer member with a second pressure contact strength smaller than the first pressure contact strength. A second blade for removing lumps;
I have a,
The transfer apparatus according to claim 2, wherein the second pressure contact strength is a strength within a range in which the toner remaining on the transfer member is not removed by the second blade and passes through . 2. The transfer device according to claim 1, wherein the second pressure contact strength is within a range in which a wax lump larger than an average particle diameter of toner can be removed by the second blade. 3. The transfer according to claim 1, further comprising a lubricant application unit that is positioned downstream of the first blade in the rotation direction of the transfer member and applies the lubricant uniformly on the transfer member. apparatus. When the length of the first blade in the width direction orthogonal to the rotation direction is W1, the length of the second blade in the width direction is W2, and the length of the lubricant application means is W3, W1 4. The transfer apparatus according to claim 3 , wherein a relationship of the following expression is established between W2, W3 and W3.
W3> W 1> W 2 A transfer device according to any one of claims 1 to 4 ,
A fixing device for fixing a toner image formed on a sheet;
A double-sided conveyance path for reversing a sheet processed with the fixing device and having a toner image formed on the surface thereof, and conveying it to the sheet transfer unit;
An image forming apparatus comprising:

Images