JP5365784B2 - Fixing apparatus and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device where oil sticking on a recording medium caused by oil retention in a separation pawl positioning member disposed at the end portion of a fixing belt is prevented, and to provide an image forming apparatus using the fixing device. <P>SOLUTION: The fixing device includes: a fixing member; a pressure member coming in press contact with the fixing member and forming a nip portion therebetween; and an oil applying means for applying the oil to the fixing member; a separation device 16 including the separation pawl 16a for separating the recording medium which has been discharged from the nip portion from the fixing member, the positioning member 16c that comes in contact with the fixing member and separates the separation pawl 16a from the fixing member only by a predetermined distance, and an oil guidance part 16d disposed adjacent to the positioning member 16c, for guiding and discharging the oil sticking to the positioning member 16c outside the recording medium conveying area. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a fixing device and an image forming apparatus including the fixing device, and more specifically, a fixing device that heats and fixes toner on a transported recording medium and a toner image formed using an electrophotographic method on the recording medium. The present invention relates to an image forming apparatus provided with the fixing device such as a copying machine, a printer, a facsimile machine, or a complex machine for fixing an image after transfer.

  In a fixing device in an electrophotographic image forming apparatus such as a copying machine or a printer, fixing performance is maintained while oil is used for a fixing member or the like to improve releasability from toner. In particular, in a full-color electrophotographic apparatus, a lot of oil is used in the fixing device.

  In recent years, the use of an endless fixing belt as a fixing member of a fixing device is often employed because of shortening of the warm-up time. For example, as shown in FIG. 1, a fixing belt 92 that is stretched over a fixing roller 84 and a heating roller 83 with a certain tension, and a pressure rotatively contacting the fixing belt 92 to form a fixing nip portion A. There is a fixing device configured to include a pressure roller 85 (see, for example, Patent Document 1).

Here, an oil application roller R1 is provided as an oil application device for applying oil to the fixing belt 92, and the oil supplied from an oil supply unit (not shown) is rotated by the rotating oil application roller R1. The abutment point 95 is applied.
Then, the oil-coated portion of the fixing belt 92 moves to the fixing nip portion A by the rotation of the fixing belt 92, and contributes to releasability from the recording medium (transfer paper) onto which the toner image is transferred.
Next, in the fixing nip portion A, a part of the oil of the fixing belt 92 has moved to the surface of the pressure roller 85, and the releasability of the pressure roller 85 is also improved. The excess oil in the pressure roller 85 flows into the oil pan 96 below the pressure roller 85 and is collected.

  Further, a separation claw 81 is disposed at the transfer paper exit of the fixing nip portion A in order to mechanically peel off the recording medium that winds around the fixing roller 84 (fixing belt 92).

  FIG. 2 shows a schematic diagram of a main part of the separation claw in the fixing device. A plurality of separation claws 81 are provided as separation claw units (separation devices) at appropriate intervals in the width direction of the fixing belt 92. When the separation claws 81 are in direct contact with the fixing belt 92 and repeatedly used, the fixing belt 92 of the separation claw contact portion is used. Therefore, the fixing belt 92 and the separation claw 81 are arranged so as to have a minute gap M (FIG. 2A). The minute gap M is close to the fixing belt 92 so that when the recording medium is fed out from the fixing nip portion A, the leading end of the separation claw 81 is sufficient to enter the leading end of the recording medium slightly separated from the fixing belt 92. It is a gap.

  Further, in order to ensure a minute gap M even when the fixing roller 84 is thermally expanded, a positioning member 82 that contacts the end surface of the fixing belt 92 outside the recording medium conveyance range and positions the separation claw 81 is provided with a separation claw. It is provided at both ends of the unit (FIG. 2B). Thereby, a constant minute gap is always secured between the fixing belt 92 and the separation claw 81.

  However, in the conventional fixing device having such a configuration, the oil applied to the fixing belt may stay in the positioning member 82 that is always in contact (FIG. 3), and the oil staying in the positioning member is intermittently generated. In other words, a large amount of the toner drops on the recording medium conveyance area of the fixing belt or the pressure roller, so that the oil adheres to the recording medium and the image quality is adversely affected.

  The present invention has been made in view of the above-described problems in the prior art, and a fixing device that prevents oil adhesion of a recording medium due to oil retention at a separation claw positioning member provided at an end portion of a fixing belt, and An object of the present invention is to provide an image forming apparatus using the fixing device.

The present invention provided to solve the above problems is as follows.
[1] A rotatable fixing member, a pressure member that presses against the fixing member to form a nip portion, an oil application unit that applies oil to the fixing member, and oil that is applied to the pressure member An oil tank to be applied, a separation claw for separating the recording medium discharged from the nip portion from the fixing member, and the separation claw abutting the fixing member at a predetermined distance from the fixing member outside the recording medium conveyance area A separation member having an oil guiding part that is provided adjacent to the positioning member and that guides and discharges the oil adhering to the positioning member to the outside of the recording medium conveyance region, And a projecting portion for guiding oil protruding from the positioning member side to the oil discharge side, and the oil is dripped from the tip of the projecting portion, so that the pressure member or the oil tank A fixing device characterized by being dropped to
[2] The oil guide portion protrudes from the positioning member side to the oil discharge side, and is formed from an end portion of the positioning member in the width direction of the fixing member to the projection portion along the width direction of the fixing member, A flange that guides oil to the protrusion, and the flange is formed by a width direction of the fixing member and a direction orthogonal to the width direction and the projecting direction of the positioning member. The planar shape has a protruding width on the oil discharge side that increases from the end of the positioning member in the width direction of the fixing member toward the protrusion. The fixing device according to [1], which is characterized in that
[3] The fixing device according to [1] or [2], wherein a surface of the oil guiding portion is made of a material having oil repellency with respect to the oil.
[4] The fixing device according to any one of [1] to [3], wherein the oil guide portion is formed integrally with the positioning member.
[5] An image forming apparatus comprising the fixing device according to any one of [1] to [4].

  According to the present invention, the oil staying in the positioning member of the separating means that comes into contact with the fixing member can be continuously discharged out of the recording medium conveyance area, so that oil adhesion to the recording medium can be suppressed. It becomes.

FIG. 10 is a cross-sectional view illustrating a configuration of a conventional fixing device. FIG. 2 is a cross-sectional view showing the arrangement of separation claws and positioning members in the fixing device of FIG. 1. FIG. 2 is a cross-sectional view showing an oil adhesion state on a positioning member in the fixing device of FIG. 1. FIG. 2 is a cross-sectional view illustrating a configuration of a fixing device according to the present invention. It is sectional drawing which shows the structure of the 1st oil application apparatus in the fixing device which concerns on this invention. It is a perspective view which shows the principal part structure of the 1st oil application apparatus used by this invention. It is sectional drawing which shows the structure of the 2nd oil application | coating apparatus in the fixing device which concerns on this invention. FIG. 3 is a top view illustrating a configuration of a separation device in the fixing device according to the present invention. FIG. 3 is a perspective view illustrating a configuration of a separation device in the fixing device according to the present invention. It is a perspective view which shows the structure (1) of the positioning member and oil guide part in the separation apparatus of FIG. It is sectional drawing which shows the oil induction | guidance | derivation / discharge | emission state in the positioning member and oil guide part of FIG. It is a perspective view which shows the structure (2) of the positioning member and oil guide part in the separation apparatus of FIG. FIG. 6 is a cross-sectional view showing another configuration example of a pressure member and a fixing member in the fixing device according to the present invention. 1 is a cross-sectional view illustrating a configuration of an image forming apparatus according to the present invention. It is the schematic which shows the structure of the oil circulation mechanism in the image forming apparatus of FIG.

The configurations of the fixing device and the image forming apparatus according to the present invention will be described below.
First, the configuration of an embodiment of a fixing device used in the present invention will be described.
As shown in FIG. 4, the fixing device 100 used in the present invention includes a fixing member (fixing member) that is a first nip forming member that is stretched around the fixing roller 11 and the heating roller 14 inside the fixing cover 100c with a constant tension. A pressure member (pressing member) that is a second nip forming member that forms a fixing nip portion (also simply referred to as a nip portion) N by being pressed against the fixing member (fixing belt 12) in a rotatable manner on the lower side. A pressure roller 13) and a recording medium discharge side of the fixing nip portion N, and a tip thereof is disposed in the vicinity of the fixing member (fixing belt 12) so that the recording medium P is wound around the fixing member (fixing belt 12). A separation claw 16a having a fluorine coating on the surface to be prevented, and a recording medium discharge side of the fixing nip portion N, the tip of which is disposed in contact with a pressure member (pressure roller 13). Addition Comprises a separation pawl 16b on the surface to prevent the winding of the recording medium P to the rollers 13) is a fluorine coating has been subjected, a cleaning mechanism 17 for cleaning the fixing belt 12 is pressed against the cleaning web, the.

  Here, the fixing belt 12 is an endless belt and has a two-layer structure in which an elastic layer such as a silicon rubber layer is formed on a base material such as nickel, stainless steel, or polyimide. The fixing roller 11 has a metal core and silicon rubber. In order to shorten the warm-up time, foamed silicon rubber may be used so that the heat of the fixing belt 12 is not easily absorbed. The heating roller 14 is an aluminum or iron hollow roller and has a heat source including a heater 14h such as a halogen heater. The heat source may be an induction heating mechanism (IH). A plurality of hollow pipes are formed in the thick portion of the hollow roller of the heating roller 14 so that the longitudinal direction thereof is the width direction of the heating roller 14, and a heat pipe 14a embedded uniformly in the circumferential direction of the heating roller 14 is provided. Have. The heat pipe 14a improves the heat transfer from the heater 14h to the roller surface, and the fixing belt 12 is heated quickly and uniformly.

  When the fixing device 100 is driven, for example, the fixing belt 12 is driven to rotate in the clockwise direction in the drawing, and the fixing belt 12 ejects the recording medium P in a state where an appropriate tension is applied by pressing the tension roller 15. It rotates in the clockwise direction in FIG. 4 and the pressure roller 13 rotates. The roller to be driven is not limited to the fixing roller 11 but may be a pressure roller 13 or a heating roller 14. Further, at the time of fixing, the fixing belt 12 is heated to a predetermined temperature (for example, a temperature suitable for toner fixing) detected by a thermistor (not shown) due to heat generated by a heater 14 h disposed inside the heating roller 14. Is done. In the present invention, the fixing belt 12 (endless belt) shown in FIG. 4 is shown as the fixing member. However, the fixing member is not limited to this and may be a hollow cylindrical roller (fixing roller).

  The pressure roller 13 is a cylindrical roller in which an elastic layer such as silicon rubber is usually provided on a core metal such as aluminum or iron. Further, the pressure roller 13 can be moved to the fixing belt 12 side by a pressure / pressure releasing means (not shown) and pressed, and the pressure roller 13 can be moved away from the fixing belt 12 to release the pressure. When 100 is driven, the pressing / depressurizing means presses the pressing roller 13 against the fixing belt 12 by pressing it toward the fixing belt 12 with a constant pressure. Further, when necessary, such as during fixing, the pressure roller 13 is heated to a predetermined temperature by the heat generated by the heater 13h disposed therein. In the present invention, the form of the pressure roller 13 (roller type) shown in FIG. 4 is shown as the pressure member. However, the present invention is not limited to this, and an endless belt shape spanning two rollers is used. It is good also as a pressurizing member (belt type).

  In the fixing device 100, the surface of the fixing belt 12 is heated to a predetermined temperature while the fixing belt 12 and the pressure roller 13 are rotationally driven, and the recording in which the unfixed toner T is formed in the fixing nip portion N is performed. The medium P is passed (paper passing from the right side to the left side in the drawing), and fixing is performed by thermally fusing unfixed toner onto the recording medium P by pressurization and heating at the fixing nip N.

  Next, the toner-fixed recording medium P is discharged from the fixing nip portion N. At this time, the recording medium P may come out while being wound around the fixing belt 12 or the pressure roller 13. As countermeasures, the oil applying device 21 which is a first oil applying device (oil applying means) for applying oil to the fixing belt 12 to improve the releasability and the releasability by applying oil to the pressure roller 13. An oil application device 22 which is a second oil application device for improving the above is provided. The oil used here is preferably a heat-resistant and non-volatile oil, such as silicone oil. In addition, the recording medium P is separated from the fixing belt 12 or the pressure roller 13 by the tips of the separation claws 16 a and 16 b coming into contact with the leading end of the recording medium P. The recording medium P discharged from the fixing nip N passes through a predetermined discharge path and is sent out from the fixing device 100.

Here, a configuration example of the first oil application device used in the fixing device 100 will be described.
FIG. 5 is a schematic view of the main part of the first oil application device in the fixing device used in the present invention. That is, the fixing device 100 used in the present invention includes a fixing member (fixing belt 12) that is rotatably provided, and a pressure member (pressure application) that contacts the fixing member and forms a fixing nip portion (fixing nip portion N). Roller 13), an oil application part (application roller 23) for applying oil to a predetermined width of the fixing member or pressure member, and an oil supply part (oil input port 21a, oil reservoir part) for supplying oil to the oil application part 21b, a support plate 21c, a supply felt 21d, a supply roller 21e, and a metering blade 21f), a first oil application device (oil supply device 21), and the oil supply unit is an oil supply device (described later). Is a bowl-shaped depression for storing oil supplied from an oil inlet and having a longitudinal direction parallel to the width direction of the oil application part. The oil reservoir portion (oil reservoir portion 21b) is provided above the adjacent oil supply member (supply felt 21d), and the oil overflows from the upper portion of the oil reservoir portion when oil is poured into the oil reservoir portion. And is configured to be supplied to the adjacent oil supply member.

FIG. 6 is a perspective view showing the configuration of the oil reservoir 21b, the support plate 21c, and the supply felt 21d, which are the main parts of the oil supply unit.
The oil reservoir 21b is a bowl-shaped depression formed of a flange 21b2 having a V-shaped cross section and a side plate 21b3 provided in a manner to block the groove of the flange at both longitudinal ends of the flange 21b2. At this time, the support plate 21c is above the supply roller 21e and the longitudinal direction of the flange portion 21b2 is parallel to the width direction of the supply roller 21e (that is, the width direction of the application roller 23 and the width direction of the fixing belt 12). It is supported by. In FIG. 6, the oil reservoir portion 21b is formed with a flange portion 21b2 by a folded end portion of the support plate 21c and a band plate fixed to the folded portion, and side plates at both longitudinal ends of the flange portion 21b2. Although the configuration in which 21b3 is fixed is shown, the present invention is not limited to this, and the flange portion 21b2 may be formed by sheet metal and the side plate 21b3 is attached, or the flange portion 21b2 and the side plate 21b3 may be integrally formed. . The oil reservoir 21b may be made of a heat-resistant metal material or plastic that does not react with the oil used.

  In addition, the end facing the adjacent oil supply member (supply felt 21d) is the other end (the other end of the flange 21b2 and the end of the side plate 21b3) of the open end of the oil reservoir 21b. It becomes a mouth cut part (mouth cut part 21b1) whose height position is lower than that. When the fixing device 100 is driven, oil is introduced into the center of the oil reservoir 21b in the width direction until the oil overflows from the oil reservoir 21b (injected from the arrow position in the figure). Oil preferentially overflows from 21b1 and is supplied to the oil application part (application roller 23) via the adjacent oil supply member (supply felt 21d) and supply roller 21e. At this time, since oil overflows from the entire width of the mouth cut portion 21b1, oil is supplied to a predetermined width (for example, full width) of the supply roller 21e and the application roller 23 via the supply felt 21d, and then the predetermined width of the fixing belt 12 is reached. The oil is applied to (for example, full width).

  The support plate 21c has a U-shaped cross section and supports the oil reservoir 21b and the supply felt 21d. At this time, the supply felt 21d can be brought into contact with the supply roller 21e with a constant pressing force if an appropriate spring characteristic is given, such as a metal material processed by sheet metal.

  The supply felt 21d is disposed adjacent to the oil reservoir 21b, and supplies oil from the upper portion of the oil reservoir 21b to the oil application part (application roll 23) side. Specifically, the supply felt 21d is between the oil reservoir 21b and the supply roller 21e and protrudes at the same height as or above the end of the mouth cut portion 21b1 of the oil reservoir 21b. It arrange | positions in contact with the oil reservoir part 21b. Further, the supply felt 21d is a compressed sheet made of, for example, a fiber that does not react with heat-resistant oil (for example, a meta-aramid fiber), and allows the oil to pass between the fibers while holding the oil inside. Is. Therefore, the fiber basis weight (mesh) of the supply felt 21d may be coarser than that for the purpose of filtering impurities. Thereby, the supply felt 21d can receive the oil overflowing from the mouth cut portion 21b1, and can flow the oil along the supply felt 21d. Here, oil flows from the upper part of the oil reservoir 21b to the supply roller 21e by the action of gravity (free fall), and the supply felt 21d supplies oil to the supply roller 21e at the contact portion with the supply roller 21e.

  In addition, the oil supply unit includes a supply roller 21e that receives oil from the supply felt 21d, and a metering blade 21f that adjusts the oil adhesion amount (holding amount) of the supply roller 21e. Among these, the supply roller 21e is made of a material corresponding to the oil used on the surface, and is made of, for example, silicon rubber. The metering blade 21f is a blade made of a material that does not damage the surface of the supply roller 21e while restricting the amount of oil adhering to the supply roller 21e, and is preferably formed of, for example, fluororubber.

With the above configuration, oil is supplied from the oil supply unit to the oil application unit as follows.
(S11) When the driving of the fixing device 100 is started, the rotation of the supply roller 21e starts with the rotation of the fixing belt 12, and the rotation of the application roller 23 in contact with the fixing belt 12 and the supply roller 21e is also started.
(S12) At the same time, oil starts to be supplied from the oil input port 21a to the oil reservoir 21b, and the oil is stored in the oil reservoir 21b.
(S13) The oil is continuously supplied, and the oil overflows from the oil reservoir 21b. At this time, the oil overflows from the full width of the mouth cut portion 21b1 and is supplied to the supply felt 21d (full width).
(S14) In the supply felt 21d, the oil passes through the inside from the upper side (upper side) of the oil reservoir 21b to the lower side, and the oil is supplied to a predetermined width of the supply roller 21e at the contact portion of the supply roller 21e.
(S15) The portion of the supply roller 21e to which the oil is supplied moves by the rotation of the supply roller 21e, and then the amount of oil adhering to the supply roller 21e is regulated by the contact of the metering blade 21f.
(S16) The oil of the supply roller 21e is supplied to a predetermined width of the application roller 23 at the contact portion with the application roller 23. Finally, the oil adhering to the application roller 23 is applied to a predetermined width of the fixing belt 12.

  As described above, in the oil application device 21, in the course of oil supply from the oil supply unit to the oil application unit, the oil flows from the upper side to the lower side using the action of gravity from the oil reservoir 21b to the supply roller 21e. Since it is configured to drop, a sufficient amount of oil can be stably supplied.

Next, a configuration example of the second oil application device used in the fixing device 100 will be described.
FIG. 7 is a schematic view of the main part related to the second oil application device in the fixing device 100 used in the present invention.
That is, the fixing device 100 according to the present invention includes a first nip forming member (fixing member (fixing belt 12)) that is rotatably provided and a second nip that is rotatably provided below the first nip forming member. A nip forming member (pressure member (pressure roller 13)) is in contact with the nip forming member (pressing roller 13) so as to form a fixing nip portion (fixing nip portion N), and holds the second oil (oil O) while holding the oil (oil O). An oil tank (oil tank 22a (sub oil pan 22a1)) provided below the nip forming member and in which a part of the second nip forming member is immersed, and the second nip forming member rotating downstream of the oil tank. And a second oil application device (oil application device 22) that is provided in front of the fixing nip portion and has an oil restriction member (blade 22b) that restricts the amount of oil adhering to the second nip forming member.

  Here, the oil tank 22a holds the oil O and a sub oil pan 22a1 that is an immersion tank in which a part of the pressure roller 13 is immersed, and a main oil pan that is an oil receiver in which the entire sub oil pan 22a1 is stored. 22 a 2, which has a two-tank structure and is fixedly arranged in the cover 100 c of the fixing device 100. At this time, the oil O applied to the pressure roller 13 is supplied to the sub oil pan 22a1 from the outside of the oil applying device 22 (oil receiver that collects excess oil of the oil applying device 21), and the oil O is supplied to the sub oil pan 22a1. It has a structure that can be stored in. The sub oil pan 22a1 is a rectangular oil pan, and its length in the longitudinal direction is at least equal to the width of the roller portion of the pressure roller 13.

  Further, the pressure roller 13 has the entire width of the roller, and a part of the roller radial direction is always immersed in the sub oil pan 22a1 without any trouble as a device. That is, the oil level of the sub oil pan 2a1 is sufficiently higher than the lower end of the pressure roller 13 in the pressurized state, and the lower end of the pressure roller 13 is in a state where the pressure roller 13 is released. The bottom surface of the sub oil pan 22a1 is not in contact. Note that the oil O only needs to be applied before the recording medium P passes through the fixing nip portion N. Therefore, the pressure roller 13 does not necessarily need to be immersed in the sub oil pan 22a1, for example, the pressure roller 13 When the rotation is started, the pressure roller 13 may be immersed in the sub oil pan 22a1.

  The main oil pan 22a2 is an oil receiver that receives the oil O overflowing from the sub oil pan 22a1. Further, an oil discharge port to an oil tank (described later) for collecting the oil O is provided at the lower part of the main oil pan 22a2.

  Note that it is preferable to use a metal material, plastic, or the like that does not react to the oil used and is heat resistant for both the sub oil pan 22a1 and the main oil pan 22a2.

  The blade 22b is a spatula-like elastic member having a width at least equal to or greater than the width of the pressure roller 13, and its longitudinal direction is always in contact with the surface of the pressure roller 13 in the width direction. The oil adhering amount at 13 is regulated to be a predetermined amount while being uniform in the width direction. The blade 22b is made of a material that does not damage the surface of the supply roller 21e, and is formed of, for example, fluororubber.

  Here, the pressure roller 13 is made of a material corresponding to the oil O used on the surface. For example, when the oil O is silicone oil, the pressure roller 13 is formed of silicone rubber. Therefore, when the pressure roller 13 is immersed in the oil O in the oil tank 22a, the silicon rubber swells and holds the oil O, but the blade 22b pressurizes the surface of the pressure roller 13 in this state. The abutment is made at the lower position of the roller 13 so that the oil O is scraped off from the pressure roller 13. Specifically, the blade 22b is disposed so that the angle θ formed between the tip of the blade 22b and the tangent line of the pressure roller 13 is an acute angle of less than 90 degrees, and the tip is opposed to the rotation direction of the pressure roller 13. It functions to scrape off excess oil O on the surface of the pressure roller 13 toward the oil tank 22a. As a result, the surface of the pressure roller 13 is in a state where a sufficient amount of oil is uniform in the width direction to ensure releasability. In addition, surplus oil in the pressure roller 13 is collected in the oil tank 22a, and a circulation system that is used for oil application to the pressure roller 13 again is configured.

  Further, the oil application device 22 preferably has a cleaning felt 22c, which is a cleaning member that contacts the pressure roller 13 and cleans the surface of the pressure roller 13 between the oil tank 22a and the blade 22b. The cleaning felt 22c is a compressed sheet made of, for example, a fiber that does not react with heat-resistant oil (for example, a meta-aramid fiber), and permeates the oil while capturing fine solid impurities inside. It is. Thereby, it is possible to remove fine solid impurities (for example, dust or calcium carbonate derived from the recording medium P) in the oil O while leaving the oil O on the surface of the pressure roller 13.

  The cleaning felt 22c is supported by an appropriate support member so as to come into contact with the pressure roller 13. However, the support member should be provided with appropriate spring characteristics, such as a metal material processed by sheet metal. For example, the cleaning felt 22c can be brought into contact with the pressure roller 13 with a constant pressing force to adjust the oil adhesion amount.

With the above configuration, oil application from the oil application unit 22 to the pressure roller 13 is performed as follows.
(S21) First, when the driving of the fixing device 100 is started, the rotation of the fixing belt 12 is started, and then the pressure roller 13 is brought into contact with the fixing belt 12 with a certain pressure by the pressure depressurizing means. N is formed. At the same time, the pressure roller 13 starts to rotate around the fixing belt 12 by rotating. The pressure roller 13 may be driven and rotated (S22) When the pressure roller 13 starts rotating, the roller surface of the pressure roller 13 immersed in the oil tank 22a (sub oil pan 22a1). However, it is pulled up in the direction of the fixing nip N with the oil O attached.
(S23) Next, the oil O adhering to the surface of the pressure roller 13 passes through the cleaning felt 22c, and solid impurities are removed.
(S24) Next, the adhesion of the oil O on the surface of the pressure roller 13 is regulated by the blade 22b so as to be uniform in the width direction, and in this state, the oil moves to the fixing nip portion N.

  As described above, in the present invention, the oil application is performed by the dipping method using the space below the pressure roller 13 with respect to the pressure roller 13 below the fixing nip portion N. It is possible to supply a stable amount of oil.

Next, the separating means that is the main configuration of the present invention will be described.
The fixing device 100 of the present invention includes a separation claw (separation claw 16a) that separates the recording medium P discharged from the fixing nip portion N from the fixing member (fixing belt 12), and abuts the separation claw by contacting the fixing member. A positioning member (positioning member 16c) that is spaced apart from the fixing member by a predetermined distance, and an oil guiding portion (oil) that guides and discharges the oil adhering to the positioning member to the outside of the recording medium conveyance area. Separating means (separating device 16) having a guiding portion 16d) is provided.

8 and 9 show a configuration example of the separation device (separation means) used in the present invention. FIG. 8 is a schematic view of the separation device 16 as viewed from above, and FIG. 9 is a perspective view of the separation device 16.
The separating device 16 has a plurality of separating claws 16a (five in FIG. 8 and seven in FIG. 9) arranged in the width direction of the fixing belt 12 (or the roller axis direction in the case of a fixing roller) and attached to the support frame 16f. It is fixed. Although an example in which a plurality of separation claws 16a are provided is shown here, the present invention is not limited to this, and a configuration having one separation claw 16a may be used. However, it is desirable to arrange a plurality of separation claws 16a so that the gap with the fixing member (fixing roller / fixing belt) can be individually adjusted, since the separation performance can be further improved.

  Here, the separation claw 16a includes a plate-like base 16a1 made of a material harder than the fluororesin, and a body portion composed of a fluororesin layer 16a2 provided on at least a main surface of the base 16a1 facing the recording medium discharge path, This is a fluororesin injection-molded product made of only resin and having a tip 16a3 having a width along the width direction of the fixing belt 12 and having a sharp tip in cross section, and using the base 16a1 as an insert member. As a result, the body portion has rigidity based on the base 16a1, and a good shape is maintained without being deformed even when the recording medium P collides. Further, since the tip end portion 16a3 is made of only a fluororesin, the fixing belt 12 is not damaged even if it contacts the fixing belt 12. Further, the recording medium discharge path side of the body part and the front end part 16a3 are made of fluororesin, so that the toner releasability is also excellent.

  Further, the separating device 16 has positioning members 16 c that are abutted against both ends in the width direction of the fixing belt 12. The positioning member 16c is disposed with the frame of the fixing device 100 as a reference via a support frame 16f, and the leading end of the positioning member 16c is abutted against both ends in the width direction of the fixing belt 12 with a constant pressure by a spring or the like. . As a result, a basic interval between the plurality of separation claws 16a and the fixing belt 12 is set. Since the positioning member 16c is installed outside the maximum sheet passing width of the fixing device 100, that is, the recording medium conveyance area, it does not adversely affect the conveyance of the recording medium P.

  Further, in the separation device 16, the interval between the tip of the leading end portion 16 a 3 and the fixing belt 12 can be adjusted as appropriate for each separation claw 16 a by a predetermined adjustment mechanism, and the leading ends of all the separation claws 16 a and the fixing belt 12. Is contactless.

  Further, the separating device 16 includes an oil guiding portion 16d that is provided adjacent to the positioning member 16c and guides and discharges the oil attached to the positioning member 16c to the outside of the recording medium conveyance area. The detailed configuration is shown in FIG.

  In FIG. 10, the oil guiding portion 16d is fixed to the support frame 16f as a separate member on the back side, that is, the lower side of the positioning member 16c. The oil guiding portion 16d does not come into contact with the fixing belt 12, and there is a space where oil flows down below the tip portion of the positioning member 16c that comes into contact with the fixing belt 12.

  The oil guiding portion 16d has a protrusion 16d2 that protrudes from the positioning member 16c side to the oil discharge side (downward in FIG. 10). The base of the protrusion 16d2 is adjacent to the positioning member 16c, and the tip of the protrusion 16d2 is located outside the recording medium conveyance area. The oil guiding portion 16d has a blade-shaped flange portion 16d1 that is adjacent to the tip portion of the positioning member 16c that contacts the fixing belt 12 and extends in the width direction of the fixing belt 12 and is connected to the protruding portion 16d2. ing. The flange portion 16d1 also has a blade whose width increases from both ends in the width direction of the oil guide portion 16d toward the projection portion 16d2, and the end portion thereof is inclined downward toward the projection portion 16d2. ing.

The function at the time of use of the oil guidance part 16d is demonstrated according to the arrow in FIG. 10, FIG.
First, the oil adhering to the positioning member 16c from the fixing belt 12 falls to the flange portion 16d1 on the oil guiding portion 16d side from the end portion of the positioning member 16c in contact with the fixing belt 12 by the action of gravity (arrow (1)). ). Then, the oil gathers at the protrusion 16d2 along the end of the flange 16d1 (arrow (2)). Next, the protrusion 16d2 guides the oil gathered on the surface from the root to the tip portion (arrow (3)), and drops the oil from the tip portion downward to discharge (arrow ( 4)).
In this way, the oil adhering to the positioning member 16c from the fixing belt 12 is sequentially discharged out of the recording medium conveyance area without staying there, so that the oil adhering to the recording medium is prevented and image quality defects are suppressed. Can do.

  The surface of the oil guiding portion 16d is preferably made of a material having oil repellency with respect to the oil in order to improve the flow of oil. The material having oil repellency with respect to oil is, for example, a fluorine-based resin that repels silicone oil to some extent, and such a material is used as a predetermined portion of the oil guiding portion 16d (for example, the oil of the flange portion 16d1 or the protrusion portion 16d2). It is better to coat the part where the light is transmitted.

  The oil guiding portion 16d preferably discharges oil in a recoverable manner. For example, it is preferable to arrange the tip portion of the protrusion 16d2 so as to be positioned above the pressure roller 13 or the oil tank 22a provided on the lower side of the pressure roller 13. As a result, the oil falling downward from the tip of the protrusion 16d2 flows through the pressure roller 13 or directly into the oil tank 22a and can be collected.

  The oil guiding portion 16d may be a positioning / oil guiding member 16e formed integrally with the positioning member 16c, as shown in FIG. This also has the same function as the oil guiding portion 16d in FIG. 10, and can guide and discharge the oil adhered to the positioning member 16c (arrows (1) to (4) in the figure).

  Here, a configuration example is shown in which a fixing member (fixing belt 12) is disposed as the first nip forming member on the upper side of the fixing device, and a pressure member (pressure roller 13) is disposed as the second nip forming member on the lower side. However, the present invention is not limited to this, and a roller type fixing member may be disposed as the first nip forming member on the upper side, and a belt type pressing member may be disposed below the second nip forming member. FIG. 13 shows an example of the configuration. Here, the fixing roller 12a, which is a first nip forming member that is rotatably arranged on the upper side, and the second nip forming member that is rotatably supported by rollers R11, R14, and R15 below the roller 12a. The fixing nip portion N can be formed by a backup member 13b which is a pressure pad on the back surface of the pressure belt 13a in contact with the pressure belt 13a. In this case, the oil application device 21 applies oil to the upper fixing member (fixing roller 12a), and the oil application device 22 applies oil to the lower pressure member (pressure belt 13a). . The separating device 16 is provided on the exit side of the fixing nip N of the fixing roller 12a.

Next, the image forming apparatus according to the present invention will be described.
FIG. 14 shows a configuration of a tandem type color copying machine which is an image forming apparatus according to the present invention.
A color copying machine 200, which is an image forming apparatus of the present invention, includes an image forming unit 200A positioned at the center of the apparatus main body, a paper feeding unit 200B positioned below the image forming unit 200A, and an upper side of the image forming unit 200A. The image forming unit is a high-speed machine having an image reading unit (not shown), and the fixing device 100 of the present invention is incorporated in the image forming unit 200A.

  The image forming unit 200A is provided with a transfer belt 210 having a transfer surface extending in the horizontal direction, and a configuration for forming an image of a color complementary to the color separation color on the upper surface of the transfer belt 210. Is provided. That is, photoconductors 205Y, 205M, 205C, and 205K as image carriers that can carry images of toners of complementary colors (yellow, magenta, cyan, and black) are juxtaposed along the transfer surface of the transfer belt 210. ing.

  Each of the photoconductors 205Y, 205M, 205C, and 205K is configured by a drum that can rotate in the same direction (counterclockwise direction), and around the optical writing device 201 that performs image forming processing in the rotation process, Charging devices 202Y, 202M, 202C and 202K, developing devices 203Y, 203M, 203C and 203K, primary transfer devices 204Y, 204M, 204C and 204K and a cleaning device are arranged. Each developing device 203Y, 203M, 203C, 203K contains a respective color toner.

  The transfer belt 210 is configured to be able to move in the same direction at a position facing the photoconductors 205Y, 205M, 205C, and 205K by being wound around a driving roller and a driven roller. Further, a transfer roller 212 is provided at a position facing a roller 211 that is one of the driven rollers. Further, the conveyance path of the recording medium P from the transfer roller 212 to the fixing device 100 is a horizontal path.

  The paper feed unit 200B separates the paper feed tray 220 on which the recording medium P as a recording medium is stacked and the recording medium P in the paper feed tray 220 from the top one by one in order from the transfer roller 212. It has a transport mechanism that transports it to a position.

  In image formation in the image forming apparatus 200 of the present invention, the surface of the photoreceptor 205Y is uniformly charged by the charging device 202Y, and an electrostatic latent image is formed on the photoreceptor 205Y based on image information from the image reading unit. Is done. The electrostatic latent image is visualized as a toner image by a developing device 203Y containing yellow toner, and the toner image is primarily transferred onto the transfer belt 210 by a primary transfer device 204Y to which a predetermined bias is applied. Is done. The other photoconductors 205M, 205C, and 205K also form similar images only with different toner colors, and the toner images of the respective colors are sequentially transferred onto the transfer belt 210 by the electrostatic force and superimposed.

Next, the toner image T primarily transferred from the photoconductors 205Y, 205M, 205C, and 205K onto the transfer belt 210 is transferred to the recording medium P conveyed by the roller 211 and the transfer roller 212. The recording medium P onto which the toner image T has been transferred is further conveyed to the fixing device 100 and is fixed at a fixing nip N between the fixing belt 12 and the pressure roller 13. Appropriate amounts of oil are applied to the fixing belt 12 and the pressure roller 13 by the oil applying devices 21 and 22, respectively, and if necessary, separation claws 16a and 16b arranged on the exit side of the fixing nip N Since it functions, the recording medium P is discharged to the exit side of the fixing nip N without being wound around the fixing belt 12 and the pressure roller 13.
Next, the recording medium P discharged from the fixing nip N is sent out to the stacker 215 along the discharge path.

  As described above, in the present invention, the image forming apparatus having the fixing device 100 can provide a more advanced fixing separation function, and can reduce various paper types (from thin paper to thick paper) and images (image leading margin). Possible).

  In the image forming apparatus 200, an oil tank 251 that collects oil for improving the releasability of the recording medium P used in the fixing apparatus 100 attached to the fixing apparatus 100, and the oil in the oil tank 251 is again used. An oil circulation mechanism such as an oil pump 252 that supplies the fixing device 100 is provided.

FIG. 15 shows a schematic configuration of an oil circulation mechanism provided in the image forming apparatus 200.
The oil circulation mechanism 250 includes an oil tank 251 that holds oil to be used, an oil pump 252 that uses a piezoelectric element, a conveyance path 253 that connects the oil pump 252 to the oil application device 21 of the fixing device 100, and an oil application device. 21, an oil receiver 254 that receives excess oil, a tube 255 that conveys the oil in the oil receiver 254 to the oil application device 22, and a conveyance path 256 that connects the oil application device 22 to the oil tank 251. The oil tank 251, the oil pump 252, the transport paths 253 and 256 are outside the fixing device 100, and the oil receiver 254 and the tube 255 are inside the fixing device 100. The oil tank 251 has an oil near-end sensor 251a that detects the remaining amount of oil inside. As a result, the first oil application device (oil application device 21) that applies oil O to the first nip forming member (fixing belt 12) and the second oil oil that is applied to the second nip formation member (pressure roller 13). 2 Assuming an oil application device (oil application device 22), an oil receiver (oil receiver 254) that collects excess oil O in the oil application device 21 and a supply path for supplying oil O from the oil receiver to the oil application device 22 ( Tube 255), an oil recovery unit (conveying path 256, oil tank 251) for recovering oil O from the oil application device 22, and an oil supply device for supplying the oil O recovered in the oil recovery unit to the oil application device 21 (An oil pump 252 and a conveyance path 253), and an oil circulation mechanism 250 is configured. As described above, the oil discharged by the oil guiding portion 16d in the separation device 16 is also recovered in the oil recovery portion (conveyance path 256, oil tank 251) via the oil tank 22a of the oil application device 22.

  In the image forming apparatus 200, the oil circulation mechanism 250 circulates and uses oil in the above-described path, and the oil application apparatuses 21 and 22 can continuously apply the oil to the fixing belt 12 and the pressure roller 13. .

  Although the present invention has been described with the embodiments shown in the drawings, the present invention is not limited to the embodiments shown in the drawings, and other embodiments, additions, modifications, deletions, etc. Can be changed within the range that can be conceived, and any embodiment is included in the scope of the present invention as long as the effects and advantages of the present invention are exhibited.

11, 12a, 84 Fixing roller 12, 92 Fixing belt 13, 85 Pressing roller 13a Pressing belt 13b Backup member 13h, 14h, 86, 87 Heater 14, 83 Heating roller 14a Heat pipe 15 Tension roller 16 Separating devices 16a, 16b , 81 Separation claw 16a1 Base 16a2 Fluororesin layer 16a3 Tip 16c, 82 Positioning member 16d Oil guiding part 16d1 Ridge part 16d2 Protruding part 16e Positioning / oil guiding member 16f Support frame 17 Cleaning mechanism 21, 22 Oil application device 21a Oil inlet 21b Oil reservoir 21b1 Opening portion 21b2 Gutter 21b3 Side plate 21c Support plate 21d Supply felt 21e Supply roller 21f Metering blade 22a Oil tank 22a1 Sub oil pad (Dip tank)
22a2 Main oil pan (oil receiver)
22b Blade 22c Cleaning felt 23, R1 Application roller 96 Oil pan 100 Fixing device 100c Fixing cover 200 Image forming apparatus (color copying machine)
200A Image forming unit 200B Paper feeding unit 201 Optical writing device 202Y, 202C, 202M, 202K Charging device 203Y, 203M, 203C, 203K Developing device 204Y, 204M, 204C, 204K Primary transfer device 205Y, 205C, 205M, 205K Photoconductor 210 transfer belt 211 driven roller 212 transfer roller 215 stacker 220 paper feed tray 250 oil circulation mechanism 251 oil tank 251a oil near end sensor 252 oil pump 253, 256 transport path 254 oil receiver 255 tube N fixing nip O oil P recording medium R11, R14, R15 Roller T Toner

JP 2003-302857 A

Claims (5)

A fixing member that is rotatably provided;
A pressure member that presses against the fixing member to form a nip portion;
An oil applying means for applying oil to the fixing member;
An oil tank for applying oil to the pressure member;
A separation claw for separating the recording medium discharged from the nip portion from the fixing member; a positioning member for contacting the fixing member outside the recording medium conveyance area and separating the separation claw from the fixing member by a predetermined distance; Separating means having an oil guiding portion that is provided adjacent to the positioning member and guides and discharges the oil adhering to the positioning member outside the recording medium conveyance area;
The oil guiding portion has a protruding portion for guiding oil protruding from the positioning member side to the oil discharging side, and the oil is dripped from the tip of the protruding portion to the pressure member or the oil tank. A fixing device that drops. The oil guiding part is
A protrusion that protrudes from the positioning member side to the oil discharge side, is formed from an end portion of the positioning member in the width direction of the fixing member to the protrusion portion along the width direction of the fixing member, and guides oil to the protrusion portion. Part
The flange has a planar shape formed by a width direction of the fixing member and a direction orthogonal to two directions of the width direction and the protruding direction of the positioning member,
2. The projecting width on the oil discharge side increases as the planar shape increases from the end of the positioning member in the width direction of the fixing member toward the protrusion . Fixing device.   The fixing device according to claim 1, wherein a surface of the oil guiding portion is made of a material having oil repellency with respect to the oil.   The fixing device according to claim 1, wherein the oil guiding portion is formed integrally with the positioning member. An image forming apparatus comprising the fixing device according to claim 1.

Images