JP2012123158A - Fixing device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device capable of preventing occurrence of waviness on a recording sheet even if the air amount is increased corresponding to a higher speed or the like when air is sprayed to separate recording sheets.SOLUTION: A fixing device, which fixes a toner image at a nip part formed by a fixing member and a pressure member, comprises: air discharging means for spraying air to a recording material to separate the recording material from the fixing member; a first guide member for guiding the recording material disposed on the fixing surface side of the recording material; a second guide member which guides the recording material disposed on the non-fixing surface side of the recording material and has a predetermined gap to the pressure member; suction means which is disposed on the opposite side of the first guide member to the second guide member and suctions air from the gap; and a rotating member which is disposed on the side of the first guide member in the second guide member and is contacted with the non-fixing surface of the recording material discharged from the nip part to rotate in the discharge direction of the recording material.

Description

  The present invention relates to a fixing device that fixes a toner image on a recording material at a nip formed by a fixing member and a pressure member, and an image forming apparatus including the fixing device.

  In an electrophotographic image forming apparatus such as a copying machine, a printer, a facsimile machine, or a multifunction machine having these functions, a latent image corresponding to an original is formed on a photosensitive member, and toner is applied to the latent image. Then, the visualized toner image is transferred onto the recording paper, and then the toner image transferred onto the recording paper is fixed and discharged.

  As a fixing device for fixing a toner image in this manner, a recording sheet onto which a toner image is transferred is sandwiched between a fixing roller having a built-in halogen heater and a pressure roller that presses the fixing roller. There is a fixing device of a heat roller fixing system that heats and pressurizes while conveying, and such a fixing device is widely used because of its simple configuration.

  In addition, an endless fixing belt is stretched between a heating roller having a halogen heater and the like and a fixing roller, and has a pressure roller that presses the fixing roller through the fixing belt. There is a belt-fixing type fixing device that heats and pressurizes while sandwiching and transporting the recording paper onto which the toner image is transferred at the nip formed by the above-mentioned fixing device, and since the fixing belt has a small heat capacity, This has the advantage of shortening the warm-up time and saving energy.

  Here, since the toner of the toner image on the recording paper is heated when passing through the nip portion, the toner has adhesive force, and the recording paper passing through the nip portion adheres to the surface of the fixing roller or the fixing belt. There is a risk of jamming due to wrapping and separation. In particular, when a small amount of paper (thin paper), especially a coated paper for printing with a small amount of paper is used as the recording paper, the separation performance is further deteriorated.

  On the other hand, the speed of image forming apparatuses is increasing, and if the fixing roller is made large to ensure a sufficiently long nip width, the roller curvature at the fixing nip outlet becomes small, so the separation performance Decreases.

  In order to make it easier to separate the recording paper from the fixing member, a heat-resistant resin having high releasability is used on the surface of the fixing member, a release agent such as silicone oil is applied, or the toner is melted by heating in the toner. Various measures have been taken, such as the inclusion of waxes that function as However, there are an increasing number of factors that decrease the separation performance, such as the image formation on the coated paper described above and the increase in the toner adhesive force due to the increase in the toner amount due to the addition of the toners of a plurality of colors forming the color image. Separation means for separating is essential.

  Separation means is provided with a separation claw coated with fluororesin having good releasability on the paper discharge side of the recording paper with respect to the nip portion, and its tip is brought into contact with the outer surface of the fixing roller or fixing belt, and the recording paper is There is a method of separating from a fixing roller or the like.

  However, since the tip of the separation claw is in contact with the surface of the fixing roller or the like, the surface layer formed of a fluororesin or the like covering the surface of the fixing roller or the like is rubbed and the wrinkle is also transferred to the image. There is a problem of end. In particular, in the case of a color image, since a glossy image is required, it tends to be noticeable.

  In order to cope with such a problem, a technique has been developed in which air is blown to the outlet side of the nip portion to separate the recording paper from a fixing roller or the like.

  As an example of this, there is known a fixing device that separates recording paper from a fixing roller by jetting compressed air generated by a compressor into a nip portion in a pulse shape (see Patent Document 1).

  In addition, a fixing device is known in which a separation claw is provided and air blown by a fan is blown to a nip portion to separate a recording sheet from a fixing roller (see Patent Document 2).

  There is also known a fixing device in which a suction fan is installed inside the belt and the recording paper after fixing is conveyed while being sucked from a hole formed in the belt (see Patent Document 3).

JP 2005-202033 A Japanese Utility Model Publication No. 63-140571 JP 2010-96953 A

  In recent years, image forming apparatuses have been increased in speed to increase the number of prints per unit time, and in order to separate recording paper corresponding to the speed increase, it is necessary to increase the amount of air to be discharged. Further, when the recording paper is thin paper, it is difficult to separate the recording paper as compared with the plain paper, so it is necessary to increase the amount of air to be discharged.

  On the other hand, air is blown toward the fixing roller in the vicinity of the nip to separate the recording paper, so that the air bounces toward the pressure roller that presses the fixing roller, and further bounces at the pressure roller. An air vortex is generated on the side. When air eddy current is generated, the behavior of the recording paper becomes unstable, and the recording paper discharged after fixing may be sucked up from the non-fixing surface side to the fixing surface side.

  The fixing surface of the recording paper means the paper surface on which the toner image is fixed by the immediately preceding fixing device, and the non-fixing surface means the back surface thereof.

  Further, guide plates for guiding the recording paper are arranged on the fixing surface side and the non-fixing surface side of the recording paper. For this reason, when the recording paper is sucked up, it is violently pressed against the guide plate on the fixing surface side, bent there, further pressed against the guide plate on the non-fixing surface side by gravity, and sucked again and pressed against the guide plate on the fixing surface side. Repeat the state. That is, a phenomenon occurs in which the recording paper undulates up and down.

  As described above, when the fixing surface of the recording paper is violently pressed against the guide plate, the toner image after fixing may be wrinkled, resulting in an image defect. In some cases, the recording paper may be deformed due to a crease in the coating layer.

  SUMMARY OF THE INVENTION The present invention has been made in view of such a problem. When recording paper is separated by blowing air, the recording paper discharged after fixing is used even if the air speed is increased or the amount of air is increased in response to thin paper. An object of the present invention is to propose an image forming apparatus provided with a fixing device configured so as not to cause an image defect due to undulations.

  In Patent Documents 1 and 2, separation is performed by blowing air, but the problem of generation of air vortex is not described, and further, the solution is not described.

  In Patent Document 3, the suction fan cools the recording paper while curling the recording paper, and does not prevent the recording paper from wavy.

  The above object is achieved by the invention described below.

1. In a fixing device that fixes a toner image on a recording material at a nip formed by a heated fixing member and a pressure member that pressurizes the fixing member.
Air discharge means for discharging air and spraying the recording material to separate the recording material from the fixing member;
A first guide member that is provided on a fixing surface side of the recording material discharged from the nip portion and guides the recording material;
A second guide member that is provided on the non-fixing surface side of the recording material discharged from the nip portion, guides the recording material, and has a predetermined gap with respect to the pressure member;
An intake means provided on the opposite side of the first guide member with respect to the second guide member, for sucking air from the gap;
A rotating member that is provided on the first guide member side of the second guide member, contacts a non-fixing surface of the recording material discharged from the nip portion, and rotates in the recording material discharge direction;
A fixing device comprising:

  2. 2. The fixing device according to 1, wherein the rotating member is an endless belt.

  3. 2. The fixing device according to 1, wherein the rotating member is a disc-shaped spur having a plurality of protrusions on an outer periphery, and the plurality of spurs are arranged in parallel.

  4). 2. The fixing device according to claim 1, wherein the rotating member is a roller, and a plurality of the rollers are arranged in parallel.

  5). The fixing device according to any one of claims 1 to 4, wherein the intake means includes an intake fan that sucks air through the gap, and an intake duct that communicates the intake fan with the gap. .

  6). 6. The fixing device according to claim 1, wherein the air discharge unit discharges air blown by a fan.

  7). Any one of the above 1 to 6, further comprising second air discharge means for discharging air generated at a high pressure by a compressor at a position opposite to the second guide member with respect to the air discharge means. The fixing device according to Item 1.

  8). The fixing device according to any one of 1 to 7, wherein the first guide member is a side wall of an exhaust duct of the air discharge unit.

  9. The fixing device according to any one of 1 to 8, wherein the second guide member is a side wall of the intake duct.

  10. The fixing device according to any one of 1 to 9, further comprising a separation claw for separating the recording material from the pressure member.

  11. An image forming apparatus comprising the fixing device according to any one of 1 to 10 above.

  According to the image forming apparatus of the present invention, when the recording paper is separated by blowing air, the recording paper is sucked from the non-fixing surface of the recording paper discharged after fixing. Will not occur. In addition, the recording paper discharged after fixing by sucking from the non-fixing surface is securely discharged without sticking to the guide member.

1 is a configuration diagram of an image forming apparatus. It is sectional drawing of a belt fixing apparatus. It is a top view of the intake duct 132 and the like in the first embodiment. It is a top view of the intake duct 132 and the like in the second form. FIG. It is an upper surface figure of the intake duct 132 etc. in a 3rd form. It is a perspective view, such as a 1st air nozzle and a solenoid valve. It is a perspective view of the 2nd air nozzle. It is a block diagram which controls a compressor and a fan.

  Embodiments relating to the present invention will be described below with reference to the drawings.

  First, an example of an image forming apparatus using the present invention will be described with reference to the block diagram of FIG.

  The image forming apparatus includes an image forming apparatus main body GH and an image reading apparatus YS.

  The image forming apparatus main body GH is called a tandem type color image forming apparatus. A plurality of sets of image forming units 10Y, 10M, 10C, and 10K, a belt-like intermediate transfer belt 5, a sheet feeding and conveying unit, a fixing device 8, and the like. Consists of.

  An image reading device YS including an automatic document feeder 201 and a document image scanning exposure device 202 is installed on the upper part of the image forming apparatus main body GH. The document d placed on the document table of the automatic document feeder 201 is transported by a transport unit, and one or both images of the document are scanned and exposed by the optical system of the document image scanning exposure device 202 and read into the line image sensor CCD. It is.

  A 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 an image processing unit, and then exposure means 3Y, 3M, 3C, 3K. Sent to.

  In the image forming unit 10Y that forms a yellow (Y) image, a charging unit 2Y, an exposure unit 3Y, a developing unit 4Y, and a cleaning unit 7Y are arranged around the photosensitive drum 1Y. In the image forming unit 10M that forms a magenta (M) color image, a charging unit 2M, an exposure unit 3M, a developing unit 4M, and a cleaning unit 7M are arranged around the photosensitive drum 1M. In the image forming unit 10C that forms a cyan (C) color image, a charging unit 2C, an exposure unit 3C, a developing unit 4C, and a cleaning unit 7C are arranged around the photosensitive drum 1C. In the image forming unit 10K that forms a black (K) image, a charging unit 2K, an exposure unit 3K, a developing unit 4K, and a cleaning unit 7K are arranged around the photosensitive drum 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 device 3C, and the charging unit 2K and the exposure device 3K constitute a latent image forming unit.

  The developing units 4Y, 4M, 4C, and 4K include a two-component developer composed of a toner having a small particle size of yellow (Y), magenta (M), cyan (C), and black (K) and a carrier. The toner is composed of a pigment or dye serving as a color former, a wax that helps the toner peel from the fixing member after fixing, and a binder resin that holds these.

  The intermediate transfer belt 5 is wound around a plurality of rollers and is rotatably supported.

  The fixing device 8 heats and pressurizes the toner image on the recording paper (recording material) P at a nip portion formed between the heated fixing belt 81 and the pressure roller 83 to fix the toner image.

  Thus, each color image formed by the image forming units 10Y, 10M, 10C, and 10K is sequentially transferred to the rotating intermediate transfer belt 5 by the transfer means 6Y, 6M, 6C, and 6K (primary transfer), and color. A combined toner image is formed. The recording paper P stored in the paper feeding cassette 20 is fed by the paper feeding means 21 and is conveyed to the transfer means 6A through the paper feeding rollers 22A, 22B, 22C, 22D, the registration rollers 23, etc. A color image is transferred to P (secondary transfer). The recording paper P to which the color image has been transferred is heated and pressurized by the fixing device 8 and the color toner image on the recording paper P is fixed. Thereafter, the sheet is sandwiched between the sheet discharge rollers 24 and placed on the sheet discharge tray 25 outside the apparatus.

  On the other hand, after the color image is transferred to the recording paper P by the transfer unit 6A, the residual toner is removed by the cleaning unit 7A from the intermediate transfer belt 5 from which the recording paper P is separated by curvature.

  The image forming apparatus for forming a color image has been described above. However, an image forming apparatus for forming a monochrome image may be used, or an intermediate transfer belt may or may not be used.

  Next, the fixing device 8 according to the present invention will be described based on the sectional view of the belt fixing device of FIG.

  The fixing belt 81 (fixing member) is formed in an endless shape. For example, PI (polyimide) having a thickness of 70 μm is used as a base, and a heat-resistant silicon rubber (hardness JIS) having a thickness of 200 μm is used with an outer peripheral surface of the base as an elastic layer. -A15 °) and further covered with a tube of PFA (perfluoroalkoxy), which is a heat-resistant resin having a thickness of 30 μm. The outer diameter is, for example, 168 mm. As other configurations, a metal substrate such as nickel electroforming may be used for the substrate, a fluorine rubber may be used for the elastic layer, or the surface release layer may be coated with PFA, PTFE (polytetrafluoroethylene), or the like.

  The heating roller 82 incorporates a halogen heater 82A as a heating means for heating the fixing belt 81. For example, the outer peripheral surface of a cylindrical metal core 82B having a thickness of 4 mm formed of aluminum or the like is formed on PTFE having a thickness of 30 μm. The resin layer 82C coated with The outer diameter is 90 mm, for example. The halogen heater 82A is composed of, for example, two of 1200 W, two of 750 W, and one of 500 W in order to cope with different paper widths, and generates different heat in the axial direction corresponding to different paper widths of the recording paper. They are arranged so that they are distributed.

  The fixing roller 83 is a solid core metal 83A formed of a metal such as iron, which is covered with a heat-resistant silicon rubber (hardness JIS-A 10 °) having a thickness of 17 mm as an elastic layer 83B, and further having a thickness of 30 μm. The resin layer 83C is coated with PTFE, which is a low friction and heat resistant resin. The outer diameter is 90 mm, for example.

  The pressure roller 84 (pressure member) incorporates a halogen heater 84A to shorten the temperature rising time immediately after the power supply to the image output apparatus is turned on, and is a cylindrical cored bar 84B having a thickness of 4 mm formed of aluminum or the like. The outer peripheral surface is covered with a heat-resistant silicone rubber having a thickness of 2 mm (hardness JIS-A 10 °) as an elastic layer 84C, and further covered with a resin layer 84D of a PFA tube having a thickness of 30 μm. The outer diameter is 90 mm, for example. The halogen heater 84A is 700 W, for example.

  The fixing belt 81 is stretched between the heating roller 82 and the fixing roller 83, and the pressure roller 84 presses the fixing roller 83 through the fixing belt 81 by an urging means (not shown).

  In the above configuration, when the pressure roller 84 is rotated counterclockwise by a driving unit (not shown), the fixing belt 81 and the heating roller 82 are rotated clockwise, and the fixing roller 83 is also rotated clockwise. Note that the fixing roller 83 may be driven. In addition, the fixing belt 81 is heated by the halogen heater 82A through the heating roller 82 that abuts, and the pressure roller 84 is also heated by the halogen heater 84A. Since the pressure roller 84 is biased toward the fixing roller 83, the fed recording material P is formed between the fixing belt 81 wound around the fixing roller 83 and the pressure roller 84. The toner image on the recording material P is fixed by being heated and pressurized at the nip portion N.

  The fixing conditions are, for example, as follows.

Fixing load: 2500N
Fixing belt tension: 250N
Fixing belt control temperature: 160-200 ° C
Pressure roller control temperature: 80-120 ° C
Recording paper transport speed: 500 mm / s
Further, any heating means may be used as the heating means for heating the fixing belt 81. For example, an induction heating heating element using an excitation coil may be used. The position where the heating means is provided is not necessarily limited to the heating roller 82.

  In addition, a tension roller that applies tension to the fixing belt 81 or a deviation control roller that controls the meandering of the belt may be provided.

  In the fixing device 8 as described above, if the fixed recording material P is ejected from the nip portion N and then attached to the fixing belt 81 and wound, there is a risk of jamming. It is necessary to ensure separation from

  Therefore, in the present fixing device 8, as the separation means, a first air nozzle 111 (second air discharge means) and a second air nozzle 121 (air discharge means) are provided in the vicinity of the exit side of the nip portion N. The first air nozzle 111 discharges compressed air generated by being compressed by the compressor, and sprays it for a short time to the vicinity of the front end portion of the recording paper P immediately after passing through the nip portion N, and the front end portion of the recording paper P is fixed to the fixing belt. Separate from 81. On the other hand, the second air nozzle 121 continuously discharges the air blown by the blower fan 123 through the exhaust duct 122 and blows it to the recording paper P from which the leading end is separated so as not to adhere to the fixing belt 81.

  The tip of the first air nozzle 111 is located at a position 25 mm from the outlet side of the nip portion N, and air is blown onto the outer peripheral surface of the fixing belt 81 at a position 10 mm from the outlet portion of the nip portion N. The tip of the second air nozzle 121 is also located at a position 25 mm from the outlet side of the nip N, and air is blown onto the outer peripheral surface of the fixing belt 81 at a position 10 mm from the outlet of the nip N. In the vicinity of the exit portion of the nip portion N, an air flow of about 40 m / s is formed from the fixing surface side of the recording paper P on the fixing roller 83 side to the non-fixing surface on the pressure roller 84 side.

  The air discharged from the first air nozzle 111 needs to have a high wind speed because the leading end of the recording paper P is separated from the fixing belt 81. However, since the discharge can be performed in a short time, the air volume may be small. On the other hand, since the air discharged from the second air nozzle 121 is after the leading end of the recording paper P has been separated, the wind speed may be lower than that of the first air nozzle 111, but until the entire recording paper P passes through the nip portion N. Since the discharge is continuously performed, the air volume is required to be larger than that of the first air nozzle 111. Note that the air volume from the first air nozzle 111 may be about 1/10 of the air volume from the second air nozzle 121. Since the first air nozzle 111 and the second air nozzle 121 supplement each other in this manner, the air tank is smaller than the configuration in which only the compressed air is discharged from the first air nozzle 111 without providing the second air nozzle 121. Can be realized, and power can be saved.

  In this manner, the recording paper P separated from the fixing belt 81 is guided from the nip N between the outer wall 122A (first guide member) of the exhaust duct 122 and a discharge guide surface 132C (second guide member) described later. Is discharged.

  Since the separation claw 86 made of heat-resistant resin is in pressure contact with the pressure roller 84, the recording paper P is pressurized even if the recording paper P is pressed downward by the air from the first air nozzle 111 or the second air nozzle 121. The roller 84 is not wound around. Further, for example, the separation claw 86 has a tip width of 12 mm, a tip R of 0.05 mm or less, the tip of the claw is located at 12 mm from the outlet of the nip portion N, and seven are arranged in the axial direction of the pressure roller 84. ing. The base material is coated with PI and PFA and has good lubricity, and is pressed against the pressure roller 84 with a weak pressure of about 1 mN, so that the pressure roller 84 is not wrinkled. In addition, even when the toner image is located on the pressure roller 84 side during double-sided copying, the temperature of the pressure roller 84 is low, so the toner image does not melt and an image defect occurs due to the separation claw 86. There is nothing to do.

  In addition, the separation claw 86 that is used in a conventional fixing device can be applied.

  Although the details will be described later, the first air nozzle 111 blows air so that the front end portion of the recording paper P does not adhere to the surface of the fixing belt 81 stretched around the fixing roller 83, and the front end portion of the recording paper P is separated. After that, the discharge of air by the first air nozzle 111 is stopped so that the recording paper P does not adhere to the surface of the fixing belt 81 stretched around the fixing roller 83 by the discharge of air by the second air nozzle 121.

  At this time, since the air discharged from the second air nozzle 121 bounces on the surface of the fixing belt 81 stretched around the fixing roller 83 and further bounces on the pressure roller 84, an air vortex is generated on the outlet side of the nip portion N. . When an air vortex is generated, the recording paper P receives a force sucked up from the non-fixing surface side to the fixing surface side, and the recording paper P is violently pressed against the side wall 122A of the exhaust duct 122, and is bent there and is bent by gravity. Are repeatedly pressed against a discharge guide surface 132C, which will be described later, and sucked again and pressed against the side wall 122A. That is, since the recording paper P undulates up and down, there is a risk that the image after fixing will be wrinkled and image defects will occur.

  Note that the air discharged from the first air nozzle 111 is intermittent and has a small air volume, so it hardly affects the generation of vortex flow.

  In order to solve such a problem, an intake means is provided. The intake means has an intake fan 130 and an intake duct 132.

  FIG. 3 is a view of the intake duct 132 as viewed from the exhaust duct 122 side. The upper wall 132 </ b> A of the intake duct 132 is disposed with a predetermined gap C with respect to the pressure roller 84. The intake fan 130 sucks air through the gap C. As a result, the recording paper P positioned in the gap C is sucked and attracted to the paper discharge guide surface 132C (second guide member) which is the outer surface of the upper wall 132A. For this reason, even if the eddy current is generated by the air discharged by the second air nozzle 121, the recording paper P does not wave up and down. Accordingly, the recording paper P is guided along the outer wall 122A of the exhaust duct 122 and the discharge guide surface 132C of the intake duct 132, and is tightly attached to the discharge roller 88 and discharged.

  A belt 200 or the like is disposed on the paper discharge guide surface 132C, which will be described later.

  When the air flow discharged from the second nozzle 121 is 40 m / s, the air flow from the gap C by the intake fan 130 is 2 m / s.

  The intake fan 130 is composed of, for example, six 40 mm square axial fans and has a static pressure of 550 Pa.

  The paper discharge roller 88 is composed of two rollers. For example, a roller on the fixing surface side of the recording paper P is formed of SUS303 with a diameter of 15 mm, and a bead coat is applied to the surface thereof. The side roller has a diameter of 15 mm and is made of silicon rubber.

  Further, instead of the plurality of separation claws 86, a separation plate that extends long in the width direction of the recording paper P may be used. Are provided with a plurality of holes.

  However, in the above-described configuration, when the leading end of the recording paper P is discharged from the nip portion formed by the two rollers of the paper discharge roller 88, the intake fan 130 is connected to the recording paper P via the gap C. Since air is sucked from between the paper discharge guide surface 132C, the recording paper P sticks to the paper discharge guide surface 132C and may not be reliably discharged. In particular, in the case of the recording paper P having a small basis weight, since the rigidity is low, the recording paper P tends to stick to the discharge guide surface 132C.

  In order to solve such a problem, it is desirable to reduce the frictional resistance between the recording paper P and the paper discharge guide surface 132C as much as possible so that the recording paper P is discharged smoothly.

  Therefore, if a rotation member that rotates in the sheet discharge direction is provided on the sheet discharge guide surface 132C, and the recording sheet P is brought into contact with the rotation member, the frictional resistance between the recording sheet P and the rotation member is small. P is discharged smoothly.

  Although various forms can be considered as a rotating member, three kinds of forms are shown below.

[First embodiment]
In this embodiment, a belt is used as a rotating member, and is shown in FIG. FIG. 3 is a view of the belt, the discharge guide surface 132C, and the like from the second nozzle 121 side.

  Two endless belts 200 are provided on the paper discharge guide surface 132C, and the belts 200 rotate in the same direction when the recording paper P is discharged in the arrow direction. The material of the belt 200 is preferably rubber such as polyvinyl chloride (PVC), polyurethane (PU), or chloroprene (CR). The diameter of the roller that stretches the belt 200 is about 10 mm, and the belt 200 protrudes from the discharge guide surface 132C by 1 to 5 mm, preferably 1 to 3 mm.

  Further, the number of belts 200 may be one or three or more. The belt 200 is desirably disposed over the entire area of the paper discharge guide surface 132C. However, when the belt 200 cannot be disposed over the entire area of the paper discharge guide surface 132C, the rib 201 is provided at a portion where the belt 200 cannot be disposed. It is desirable to arrange. The rib width is desirably 2 to 15 mm, the height is 0.5 to 1.5 mm, and the rib interval is desirably 5 to 20 mm.

  The belt 200 is rotated by a driving source (not shown).

[Second form]
This embodiment uses a spur as a rotating member, and is shown in FIGS. FIG. 4 is a view of the spur, the paper discharge guide surface 132C, and the like from the second nozzle 121 side. FIG. 5 is a view of a spur, FIG. 5 (a) is a front view of the spur, and FIG. 5 (b) is an AA cross-sectional view of the spur.

  A plurality of spurs 300 are rotatably provided on the discharge guide surface 132C, and the spurs 300 rotate in the same direction when the recording paper P is discharged in the arrow direction.

  As shown in FIG. 5, the spur 300 is formed in a disk shape and has a plurality of protrusions 300A on the outer periphery. The projection 300A comes into contact with the recording paper P to be discharged, and the spur 300 rotates. The diameter of the spur 300 is 3 to 20 mm, and the thickness of the peripheral thin portion is preferably 0.3 to 0.5 mm. If the diameter is larger and the protrusion 300A is larger than this, the leading end of the recording paper P may collide with the protrusion 300A and become wrinkled. The material of the spur 300 is a resin such as polyacetal (POM), polyimide (PI), polyamideimide (PAI) or polycarbonate (PC), or a metal such as stainless steel.

  Such spurs 300 protrude from the paper discharge guide surface 132C, and are arranged in parallel in the discharge direction of the recording paper P and in a direction orthogonal to the direction. Further, it is desirable that the spur 300 is disposed over the entire discharge guide surface 132C. It is desirable that the spur 300 protrude from the discharge guide surface 132C by 1 to 4 mm. However, if the spur 300 protrudes from the nip portion of the discharge roller 88, the leading end of the recording paper P may collide with the protrusion 300A and become wrinkled. is there.

  Moreover, you may provide the rib 301 between each spur 300, The width | variety of the rib of the rib 301 is 2-15 mm, height is 0.5-1.5 mm, and rib interval is 5-20 mm.

  The spur 300 is provided so as to be rotatable independently without being driven to rotate.

[Third embodiment]
In this embodiment, a roller is used as a rotating member, and is shown in FIG. FIG. 6 is a view of the rollers, the discharge guide surface 132C, and the like as viewed from the second nozzle 121 side.

  A plurality of rollers 400 are arranged in the discharge direction of the recording paper P on the discharge guide surface 132C, and the rollers 400 rotate in the same direction when the recording paper P is discharged in the arrow direction. When the recording paper P is discharged, the roller 400 may be rotated by a driving source (not shown) or may be rotated freely without being driven. When the roller 400 is rotated by a drive source, the roller diameter is desirably 5 to 25 mm, and the material is desirably a resin such as polyacetal or urethane, or a metal such as stainless steel. On the other hand, when the roller 400 rotates freely without being driven, the roller diameter is desirably 5 to 10 mm, and the material is desirably polytetrafluoroethylene (PTFE) or polyacetal (POM).

  The roller 400 preferably protrudes from the discharge guide surface 132C by 3 to 5 mm.

Using the belt 200, the spur 300, and the roller 400 as described above, the sheet passing test was performed by changing the thickness of the recording paper to be used.
(1) Experimental conditions: Image forming apparatus and fixing apparatus: configuration shown in FIGS. 1 and 2 Rotating member No rotating member: No coating on paper discharge guide surface 132C Belt: Central part (about width direction) 1/3) only arrangement, 2 types of full arrangement Spur: 4 types of ribs with diameter 5, 10, 15, 20, 25 mm, no ribs, 10 mm diameter with ribs Roller: 3 types of diameters 5, 10, 15 mm, all rotating Without driving.
・ Recording paper Coated paper OK Medium coat L60g ・ ・ ・ ・ ・ ・ P1
Kinto 85g ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ P2
OK top coat 85g ・ ・ P3
OK top coat 128g P4
Plain paper Konica Minolta J paper (64g) P5
The recording paper used is all A3.
-Number of printed sheets 1000 consecutive sheets (2) Experimental results Table 1 shows.

However,
○: Normal discharge of recording paper △: Wrinkle generated at the leading edge of the recording paper ×: Generation of defective recording paper discharge (3) Consideration When belts, spurs and rollers are not used, normal paper can be discharged normally, but thin paper With this coated paper, even when the paper discharge guide surface 132C was coated, a discharge failure occurred.

  When the belt is used, the recording paper discharge failure occurs in the thin coated paper when the belt is disposed only in the center portion, but any recording paper can be normally discharged when the belt is disposed over the entire surface.

  When using a spur, when the diameter increases to 25 mm, the leading edge of the recording paper comes into contact with the spur and wrinkles occur at the leading edge, but any recording paper can be discharged normally regardless of the presence or absence of ribs from 5 mm to 20 mm. It was.

  When a roller was used, when the diameter increased to 15 mm, the leading edge of the recording paper contacted the roller and wrinkles occurred at the leading edge, but any recording paper could be discharged normally at 5 mm and 10 mm.

  Next, a configuration for discharging air from the first air nozzle 111 and the second air nozzle 121 will be described with reference to FIGS. 7 is a perspective view of the first air nozzle 111 and the electromagnetic valve, FIG. 8 is a perspective view of the second air nozzle 121, and FIG. 9 is a block diagram for controlling the compressor and the fan.

  First, the 1st air nozzle 111 and its related structure are demonstrated based on FIG.7 and FIG.9.

  In FIG. 7, five first air nozzles 111 are arranged in the width direction of the recording paper P, and each of the first air nozzles 111 is provided with 13 nozzle holes 111a having a diameter of 1 mm at a pitch of 5 mm. Accordingly, the total number of nozzle holes 111a is 65 with the five first air nozzles 111.

  The five first air nozzles 111 are connected to the two piping parts 113 by the five pipes 112 respectively, and the two piping parts 113 communicate with the two electromagnetic valves 114, respectively. Although the shape of the tip from the solenoid valve 114 is not shown, it is connected to and integrated with the air tank 115 shown in FIG. 12, and the air tank 115 is connected to the compressor 116.

The solenoid valve 114 is a direct acting type, has a capacity of 0.001 m ³ / s (100 kPa), and a response speed of 20 ms.

The capacity of the air tank 115 is 0.05 m ³ .

The compressor 116 is a reciprocating oil-free type, and has an electric power of 0.75 kW, a static pressure of 0.8 MPa, and an air volume of 0.00125 m ³ / s.

  In the image forming apparatus having the above configuration as shown in FIG. 1, the paper feed sensor 102 detects that the recording paper P accommodated in the paper feed cassette 20 has been fed by the paper feed means 21. The time until the conveyed recording paper P passes through the nip portion N from the time of detection by the paper feed sensor 102 is constant and known in advance, and the control means 101 comprising a CPU or the like indicates that the time has been reached by the timer 103. Upon recognition, an open signal is transmitted to the electromagnetic valve 114, and a close signal is transmitted after 50 ms. Since the compressed air compressed by the compressor 116 is stored in the air tank 115 in advance, the compressed air is discharged from the first air nozzle 111 along with the opening of the electromagnetic valve 114 and immediately after passing through the nip portion N. Spray against the tip of the.

At this time, the compressed air of about 0.8 MPa stored in the air tank by the compressor is decompressed by a regulator (not shown) provided between the air tank and the first air nozzle and supplied to the first air nozzle 111. The discharge pressure from the first air nozzle 111 is 0.1 to 0.2 MPa, the discharge speed is 100 to 160 m / s, and the discharge air volume is 0.005 to 0.008 m ³ / s.

  Further, since the electromagnetic valve 114 is fully opened about 20 ms after the opening signal is inputted, the maximum air volume is reached when the recording paper P is conveyed about 10 mm from the nip portion. Since the maximum discharge air volume of compressed air from the first air nozzle 111 is 2 to 3 times the air volume necessary for separating the recording paper P, the recording paper P has to be discharged before the compressed air discharge air volume reaches the maximum, that is, the nip portion. Separation begins before the transport distance from N reaches 10 mm. Thereafter, when a closing signal is input to the electromagnetic valve 114, the discharge air volume of the compressed air discharged from the first air nozzle 111 gradually decreases, and the leading edge of the recording paper P reaches 25 to 30 mm from the nip portion N. Continue to discharge. The amount of air discharged at this time is the amount of air that can peel the recording paper P even if there is a toner image with the maximum adhesion amount.

  In FIG. 10, the three first air nozzles 111b arranged on the inner side are connected to the electromagnetic valve 114a via the piping part 113a, and the two first air nozzles 111c arranged on the outer side are connected via the piping part 113b. Are connected to the electromagnetic valve 114b. The widths of the three first air nozzles 111b correspond to dimensions in the short side direction of A4 size, for example, and the widths of the five first air nozzles 111b and 111c correspond to dimensions in the long side direction of A4 size, for example. Then, based on an input to an operation panel arranged on the upper part of the image reading apparatus, the recording paper size detection unit 104 detects the size of the recording paper on which an image is to be formed and transmits it to the control unit 101.

  In this way, when A4 size recording paper is fed laterally, the control means 101 transmits an open signal to both the electromagnetic valve 114a and the electromagnetic valve 114b. However, when A4 size recording paper is fed vertically, the control means 101 transmits an open signal only to the electromagnetic valve 114a and does not transmit an open signal to the electromagnetic valve 114b. As a result, useless discharge of compressed air can be suppressed and the power consumption of the compressor 116 can be reduced.

  At this time, the halogen heater built in the heating roller also energizes the one corresponding to the paper passing area to suppress power.

  As described above, after the compressed air is discharged from the first air nozzle 111 and the leading end portion of the recording paper P that has passed through the nip portion N is separated from the fixing belt 81, the discharge of the compressed air is stopped, and instead the second air nozzle The air blown by the fan from 121 is continuously discharged and blown onto the recording paper P to prevent the recording paper P from adhering to the fixing belt 81.

  That is, when the separation of the recording paper P proceeds to some extent and the leading end of the recording paper P is opened by 0.2 mm or more from the fixing belt 81, the first air nozzle 111 is used in order to apply a peeling force to all the open areas. Air that blows in a wide range with a large air volume even at low pressure is preferable to air that blows in a narrow range at high pressure, such as compressed air to be discharged. Therefore, the discharge from the first air nozzle 111 is stopped, and the air blown by the fan from the second air nozzle 121 is blown to the leading end of the recording paper P that is opened from the fixing belt 81. As a result, even if there is no spray from the first air nozzle 111, a force is applied to the recording paper P against the adhesive force of the toner, and the recording paper P is reliably separated from the fixing roller 81.

  Below, the 2nd air nozzle 121 and its related structure are demonstrated based on FIG.8 and FIG.9.

  In FIG. 8, five second air nozzles 121 are arranged in the width direction of the recording paper P, and the opening size of each second air nozzle 121 is 60 mm in the width direction of the recording paper P and the thickness direction of the recording paper P. Is formed to 1.6 mm.

  The five second air nozzles 121 communicate with the positions of the five blower fans 123 by the exhaust duct 122 as shown in FIG.

  The blower fan 123 is a 97 mm × 33 mm sirocco fan, with a rated voltage of 24 V and a maximum static pressure of 1280 Pa.

  In the image forming apparatus having the above configuration as shown in FIG. 1, when the paper feed sensor 102 detects that the recording paper P accommodated in the paper feed cassette 20 has been fed by the paper feed means 21, the control means 101. Energizes the fan switch 124. Accordingly, each blower fan 123 starts rotating, and air is discharged from the second air nozzle 121 at, for example, 20 m / s and blown onto the recording paper P, and the recording paper P is separated from the fixing belt 81. When the recording paper P is continuously fixed, the blower fan 123 is kept operating. However, if the responsiveness of the blower fan 123 is sufficiently high as will be described later, it is turned on / off in accordance with the entry of the recording paper P. You may repeat off.

Thus, even a thin coated paper for printing having a thickness of about 80 g / m ² on which a solid image having the maximum adhesion amount is placed can be continuously separated.

  The reason why the fan switch 124 is energized before the recording paper P reaches the fixing device 8 is that there is a time lag from when the blower fan 123 is energized until the maximum rotation speed is reached. If the recording paper conveyance speed is low and the air blowing fan 123 can reach a sufficient wind speed to continue the separation described later before reaching the position where the recording paper P is to be separated, the recording is performed. It may be activated after the paper P reaches the fixing device. Conversely, when a blower or the like that has a high output but takes a long time to start up is used as the blower fan 123, such as when the present invention is applied to a higher-speed image forming apparatus, the image forming apparatus starts feeding and further performs an image forming operation. Prior to the start, the start timing of the blower fan 123 is appropriately selected, such as starting the blower.

The discharge pressure from the second air nozzle 121 is 400 Pa, the discharge air speed is 20 to 30 m / s, and the discharge air amount is 160 × 10 ⁻⁵ m ³ / s.

  Further, the blower fan 123 is not limited to a sirocco fan, and may be an axial fan, a cross flow fan, a blower, or the like. In short, the recording paper P with the leading end separated from the fixing belt 81 is continuously peeled off. What is necessary is just to have the conditions which have a possible air volume. The shape of the exhaust duct 122 is set according to the type of the blower fan 123.

  In FIG. 8, five second air nozzles 121 are arranged in the width direction of the recording paper P. Similarly to the first air nozzle 111, the width of the three second air nozzles 121a arranged on the inner side corresponds to a dimension in the short side direction of A4 size, for example, and is arranged on the outer side with the three second air nozzles 121a. The widths of the two second air nozzles 121b correspond to dimensions in the long side direction of A4 size, for example. The three second air nozzles 121a communicate with the three blower fans 123, respectively, and the two second air nozzles 121b communicate with the two blower fans 123, respectively. When the A4 size recording paper is fed laterally, the control means 101 energizes both the fan switch 124 corresponding to the second air nozzle 211a and the fan switch 124 corresponding to the second air nozzle 211b disposed outside. However, when the A4 size recording paper is fed vertically, the control means 101 energizes only the fan switch 124 corresponding to the second air nozzle 211a. As a result, unnecessary rotation of the blower fan 123 and cooling of the fixing member by wind for separation can be suppressed, and power consumption of the blower fan 123 and the halogen heater 82A can be reduced.

  Further, the control means 101 turns on the suction fan switch 133 by the detection of the paper feed sensor 102 and the like before the leading edge of the recording paper P reaches the fixing device 8 and stably rotates the intake fan 130. Then, after the printing is completed, the suction fan switch 133 is turned off to stop the rotation of the intake fan 130.

  In the fixing device described above, when the recording paper P discharged after fixing is wavy, and the recording paper P is sucked from the back surface (non-fixing surface) side of the recording paper P in order to suppress the wavy, the recording paper P Is likely to stick to the paper discharge guide surface 132C, the greater the smaller the basis weight of the recording paper P, the greater the effect. In general, the recording paper P having a small basis weight has low rigidity, and therefore, if eddy currents are generated, the recording paper P is likely to be wavy and stick to the paper discharge guide surface 132C. On the other hand, the recording paper P having a large basis weight has high rigidity, so that even if eddy currents are generated, it is difficult for undulation to occur and it is difficult to stick to the paper discharge guide surface 132C. Accordingly, the suction force of the intake fan 130 may be reduced as the basis weight of the selected recording paper P increases. That is, unnecessary power consumption can be suppressed by reducing the current flowing through the intake fan 130 to reduce the air volume.

  Further, instead of guiding the non-fixing surface of the recording paper P along the discharge guide surface 132C which is the outer surface of the upper wall 132A of the intake duct 132, a dedicated discharge is provided between the exhaust duct 122 and the intake duct 132. A guide plate may be arranged so that the non-fixing surface of the recording paper P is guided along the discharge guide plate.

  Further, the fixing device 8 includes the first air nozzle 111 that discharges compressed air and the second air nozzle 121 that discharges air blown by a fan. However, only one of the first air nozzle 111 and the second air nozzle 121 is provided. The recording paper P can also be separated as an air discharge means, and eddy currents may be generated by the discharged air. Therefore, the present invention can be applied to such a case.

  In addition, the present invention is not limited to the fixing device shown in FIG. 2 and may be any type of fixing device.

DESCRIPTION OF SYMBOLS 8 Fixing device 81 Fixing belt 82 Heating roller 83 Fixing roller 84 Pressure roller 85 Paper discharge guide plate 86 Separation claw 88 Paper discharge roller 101 Control means 111 1st air nozzle 121 2nd air nozzle 122 Exhaust duct 122A Outer wall 130 Suction fan 132 Suction duct 132C Paper discharge guide surface 200 Belt 201, 301 Rib 300 Spur 400 Roller P Recording material N Nip part C Gap

Claims (11)

In a fixing device that fixes a toner image on a recording material at a nip formed by a heated fixing member and a pressure member that pressurizes the fixing member.
Air discharge means for discharging air and spraying the recording material to separate the recording material from the fixing member;
A first guide member that is provided on a fixing surface side of the recording material discharged from the nip portion and guides the recording material;
A second guide member that is provided on the non-fixing surface side of the recording material discharged from the nip portion, guides the recording material, and has a predetermined gap with respect to the pressure member;
An intake means provided on the opposite side of the first guide member with respect to the second guide member, for sucking air from the gap;
A rotating member that is provided on the first guide member side of the second guide member, contacts a non-fixing surface of the recording material discharged from the nip portion, and rotates in the recording material discharge direction;
A fixing device comprising:   The fixing device according to claim 1, wherein the rotating member is an endless belt.   The fixing device according to claim 1, wherein the rotating member is a disc-shaped spur having a plurality of protrusions on an outer periphery, and the plurality of spurs are arranged in parallel.   The fixing device according to claim 1, wherein the rotating member is a roller, and a plurality of the rollers are arranged in parallel.   5. The fixing according to claim 1, wherein the intake unit includes an intake fan that sucks air through the gap, and an intake duct that communicates the intake fan with the gap. apparatus.   The fixing device according to claim 1, wherein the air discharge unit discharges air blown by a fan.   7. The second air discharge means for discharging air generated at a high pressure by a compressor at a position opposite to the second guide member with respect to the air discharge means. The fixing device according to claim 1.   The fixing device according to claim 1, wherein the first guide member is a side wall of an exhaust duct of the air discharge unit.   The fixing device according to claim 1, wherein the second guide member is a side wall of the intake duct.   The fixing device according to claim 1, further comprising a separation claw for separating the recording material from the pressure member.   An image forming apparatus comprising the fixing device according to claim 1.

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