JP6135212B2 - Fixing apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a fixing device that fixes a toner image on a recording medium, and an image forming apparatus including the fixing device.

  Conventionally, in the above-described image forming apparatus, first, an unfixed toner image is transferred to a recording material sheet, printing paper, photosensitive paper, electrostatic recording paper, and the like by an image forming process such as electrophotographic recording, electrostatic recording, and magnetic recording. Formed on the recording medium. After that, the toner image on the recording medium is fixed by conveying the recording medium between the fixing roller and the pressure roller constituting the fixing device. As this fixing device, a contact heating method such as a heat roller method, a film heating method, and an electromagnetic induction heating method is widely adopted (Patent Documents 1 to 3).

  The fixing device described above may be conveyed downstream (including the fixing device itself in the case of double-sided conveyance) in an incorrect posture, such as curling of the recording medium, which may cause problems in conveyance of the recording medium. Also, due to the surface pressure deviation in the rotation axis direction of the fixing nip formed by the fixing roller and the pressure roller, the recording medium cannot maintain the correct posture, and the recording medium is wrinkled or the recording medium is There is also a risk that the unfixed toner image may be disturbed by floating. These problems are listed as examples.

  These problems are designed such that the conveyance speed of the recording medium 2 does not occur in general usage. However, the environment in which the image forming apparatus is placed is bad or the recording medium 2 with poor quality may be conveyed. In this case, it was very difficult to ensure that no problem occurred.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a fixing device and an image forming apparatus capable of transporting a recording medium in a correct posture and improving image quality and transportability. To do.

The invention according to claim 1, which has been made to solve the above-described problem, includes a fixing roller to be heated and a pressure roller that presses the fixing roller, and is provided between the fixing roller and the pressure roller. A fixing device comprising: a fixing unit that fixes a toner image on the recording medium by conveying the recording medium between the fixing unit; and a conveying unit that conveys the recording medium to the fixing unit. Posture detecting means for detecting the posture of the recording medium upstream of the means in the conveying direction, and conveyance of the recording medium by the fixing means or the conveying means according to the attitude detected by the posture detecting means, or , and a control means for controlling the pressure of the pressure roller, the posture detection means, the recording medium occurring at the tip of the recording medium before the recording medium is conveyed to the fixing unit The control unit detects a first posture abnormality that is floating in the thickness direction of the recording medium, and the control unit continuously conveys the recording when the posture detection unit detects the first posture abnormality. In the fixing device, the conveyance of the recording medium by the fixing unit or the conveyance unit is controlled so as to widen the interval between the medium and the recording medium .

  According to the fixing device of the first aspect, the control unit controls the conveyance of the recording medium by the fixing unit or the conveyance unit or the pressure of the pressure roller according to the posture of the recording medium detected by the posture detection unit. Since the control is performed, the recording medium can be transported in a correct posture, and the image quality and transportability can be improved.

1 is a schematic configuration diagram of a fixing device according to an embodiment of the present invention. FIG. 2 is a view taken in the direction of arrow Y1 in FIG. 1. It is explanatory drawing for demonstrating operation | movement of the thermal fixing apparatus shown in FIG. It is explanatory drawing for demonstrating operation | movement of the thermal fixing apparatus shown in FIG. It is a figure which shows the detail of the attitude | position detection mechanism shown in FIG.3 and FIG.4. It is an electrical block diagram of the heat fixing apparatus shown in FIG. It is a figure for demonstrating other embodiment of the attitude | position detection mechanism shown in FIG. 1 is a schematic configuration diagram of a tandem type color copier that is an image forming apparatus according to an embodiment of the present invention.

(Embodiment of fixing device)
A fixing device and an image forming apparatus according to the present invention will be described with reference to FIGS.

  As shown in FIG. 1, the fixing device 1 includes a fixing unit 3 that fixes a toner image T on a recording medium 2, a conveyance sensor 4, a conveyance tank 5 that conveys the recording medium 2 to the fixing unit 3, and an entrance guide plate. 6 and an attitude detection mechanism 7. The fixing unit 3 corresponds to the fixing unit in the claims, the transport tank 5 corresponds to the transport unit in the claims, and the posture detection mechanism 7 corresponds to the posture detection unit in the claims.

  The recording medium 2 is a recording material sheet, printing paper, photosensitive paper, electrostatic recording paper, OHP film, or the like. The fixing unit 3 includes a fixing roller 8, a heating roller 9 that heats the fixing roller 8, a fixing belt 10 that is stretched over the fixing roller 8 and the heating roller 9, and a pressure roller 11 that presses the fixing roller 8. It is equipped with. In the fixing unit 3, the toner image T on the recording medium 2 is fixed by conveying the recording medium 2 between the fixing roller 8 and the pressure roller 11.

  The fixing roller 8 is provided with an elastic layer 8b such as silicone rubber on a metal core 8a such as aluminum or iron (including respective alloys). For the elastic layer 8b of the fixing roller 8, foamed silicone rubber may be used so that the heat of the fixing belt 10 is not easily absorbed in order to shorten the warm-up time.

  The heating roller 9 is a hollow roller made of aluminum or iron, and is opposed to the fixing roller 8 with an interval so that the shafts are parallel to each other. The heating roller 9 has a heat source (not shown) such as a halogen heater or an electromagnetic induction heating mechanism (IH) inside or outside thereof. The heating roller 9 has a negligible thermal expansion compared to the fixing roller 8 having the elastic layer 8b.

  The fixing belt 10 is an endless belt and has a two-layer structure in which an elastic layer such as a silicone rubber layer is formed on a base material such as nickel, stainless steel, or polyimide. The fixing belt 10 is wound around the fixing roller 8 and the heating roller 9 with a constant tension. The inner peripheral surface of the fixing belt 10 and the outer peripheral surfaces of the fixing roller 8 and the heating roller 9 are set in a frictional relationship that does not cause slip. Therefore, when the fixing roller 8 rotates, the fixing belt 10 rotates and the heating roller 9 is rotated by the rotation movement of the fixing belt 10.

  The pressure roller 11 is a cylindrical roller in which an elastic layer 11b such as silicone rubber is provided on a metal core 11a made of aluminum or iron. The pressure roller 11 is rotatably arranged on the lower side in the figure with respect to the fixing belt 10, and its outer peripheral surface is pressed against the outer peripheral surface of the fixing roller 8 via the fixing belt 10. A portion where the fixing roller 8 and the pressure roller 11 are pressed through the fixing belt 10 is referred to as a fixing nip portion N.

  The conveyance sensor 4 is disposed downstream of the fixing nip portion N in the conveyance direction. The conveyance sensor 4 includes an optical sensor and the like, detects the leading end and the trailing end of the recording medium 2, and transmits a detection signal corresponding to the detection to a posture control unit 12 described later and a controller unit 16 as a control unit. . The controller unit 16 can detect the passage of the leading end and the trailing end of the recording medium 2 based on the detection signal from the transport sensor 4 and can measure the speed of the recording medium 2 based on the passing time of the leading end and the trailing end. ing. The conveyance sensor 4 is provided downstream of the fixing nip N in the conveyance direction, that is, at the outlet of the fixing unit 3. However, a sensor provided at the inlet of the fixing unit 3 or the conveyance tank 5 may be used. Good.

  The transport tank 5 is provided upstream of the fixing unit 3 in the transport direction of the recording medium 2. The transport tank 5 includes, for example, a plurality of transport rollers 5a and a transport belt 5b that is stretched over the plurality of transport rollers 5a and rotates by the rotation of the transport rollers 5a. The recording medium 2 on which the unfixed toner image T is formed is placed on the conveying belt 5b and conveyed to the fixing unit 3.

  The inlet guide plate 6 is a guide plate that guides the recording medium 2 conveyed by the conveyance tank 5 to the fixing unit 3. The inlet guide plate 6 is provided between the end of the conveying tank 5 on the fixing unit 3 side and the inlet of the fixing nip N, and guides the recording medium 2 conveyed by the conveying tank 5 to the inlet of the fixing nip N. .

  The posture detection mechanism 7 detects the posture of the recording medium 2 upstream of the fixing unit 3 in the transport direction, that is, detects the lifting of the recording medium 2 in the thickness direction as a posture abnormality. The posture detection mechanism 7 is disposed above the transfer tank 5 and the inlet guide plate 6 and between the transfer tank 5 and the inlet guide plate 6. As shown in FIG. 2, a plurality of posture detection mechanisms 7 are arranged side by side along the width direction orthogonal to the conveyance direction of the recording medium 2.

  As shown in FIGS. 3 to 5, the posture detection mechanism 7 includes a spur 7 a and a spur rise detection sensor 7 b that detects the rise of the spur 7 a. As illustrated in FIG. 5 and the like, the spur 7a includes a rotation shaft 7a1, a spur body 7a2, and a spring 7a3. The rotation shaft 7a1 is provided along the width direction. The spur body 7a2 is rotatably attached to the rotation shaft 7a1. The spring 7a3 is attached to the rotating shaft 7a1, and supports the rotating shaft 7a1 and the spur body 7a2 so as to be movable in the vertical direction.

  The spur rise detection sensor 7b is composed of, for example, a transmission type sensor. As shown in FIG. 5, when the spur 7a is not pushed up by the recording medium 2, the spur rise detection sensor 7b is configured such that the rotation shaft 7a1 is positioned outside the gap 7b1. Further, the spur rise detection sensor 7b is configured such that when the spur 7a is pushed up to the recording medium 2, the rotating shaft 7a1 is inserted into the gap 7b1 as shown in FIGS. The spur rise detection sensor 7b detects the insertion of the rotation shaft 7a1 as the rise of the spur 7a by using an optical sensor or the like to insert the rotation shaft 7a1 into the gap 7b1, and transmits the detection signal to the attitude control unit 12 described later. To do.

  As the spur rise detection sensor 7b, not only whether or not the spur 7a has risen, but also the spring rate of the spring 7a3 may be adjusted as appropriate so that the degree of rise can be detected. In this case, as the spur rise detection sensor 7b, it is possible to use a plurality of transmission sensors or a pressure sensor that detects the pressure of the spring 7a3.

  In the example shown in FIG. 5, the spur rise detection sensor 7b is provided only on one side (the right side of the drawing) of the rotation shaft 7a1, but the present invention is not limited to this. The spur rise detection sensor 7b may be provided at both ends of the rotating shaft 7a1 so that the upward movement of the spur 7a can be detected, and the posture of the recording medium 2 can be detected in more detail.

  Further, as the posture detection mechanism 7, instead of the spur 7a and the spur rise detection sensor 7b, an optical sensor 7c may be used as shown in FIG.

  As shown in FIG. 6, the fixing device 1 includes an attitude control unit 12, a fixing roller rotation motor 13, a conveyance roller rotation motor 14, a pressure roller drive unit 15, and a controller unit 16. It is equipped with.

  As described above, the detection signal from the attitude detection mechanism 7 is input to the attitude control unit 12. When the floating of the recording medium 2 is detected, the posture control unit 12 determines whether the floating is a first posture abnormality as shown in FIG. 4 or a second posture abnormality as shown in FIG. The first posture abnormality is a posture abnormality (curl abnormality) occurring at the leading end of the recording medium 2 before the recording medium 2 is conveyed to the fixing unit 3 as shown in FIG.

The second posture abnormality is a posture abnormality on the upstream side in the transport direction from the fixing unit 3 of the recording medium 2 while the recording medium 2 passes through the fixing unit 3 as shown in FIG. Whether or not the recording medium 2 is passing through the fixing unit 3 can be identified by the conveyance sensor 4. For this reason, the posture control unit 12 determines that the second posture abnormality is detected when floating is detected while the recording medium 2 passes through the fixing unit 3, and determines that the first posture abnormality is detected if elevation is detected before passing. . As is clear from the above, the posture detection mechanism 7 and the posture control unit 12 correspond to the posture detection means in the claims.

  The fixing roller rotating motor 13 is a motor that rotates the fixing roller 8. The transport roller rotating motor 14 is a motor that rotates the transport roller 5a. The pressure roller drive unit 15 adjusts the pressure applied to the fixing roller 8 by moving the pressure roller 11 toward and away from the fixing roller 8. When the pressure roller driving unit 15 moves the pressure roller 11 in a direction to approach the fixing roller 8, the pressure is increased. On the other hand, when the pressure roller 11 is moved away from the fixing roller 8, the applied pressure is weakened.

  The controller unit 16 is configured by a computer or the like, and controls the fixing roller rotating motor 13, the conveying roller rotating motor 14, and the pressure roller driving unit 15. In the present embodiment, the controller unit 16 detects the first posture abnormality and the second posture abnormality detected by the posture control unit 12, the fixing roller rotation motor 13, the conveyance roller rotation motor 14, and the pressure roller drive unit 15. Change the control.

  Next, an example of a fixing operation in the fixing device 1 will be described.

  In the fixing device 1, during the fixing operation, the transport roller rotating motor 14 drives the transport roller 5 a to rotate counterclockwise in the drawing based on a control signal from the controller unit 16. Further, based on a control signal from the controller unit 16, the fixing roller rotating motor 13 drives the fixing roller 8 to rotate in the clockwise direction in the drawing. Then, the recording medium 2 is transported toward the fixing unit 3 in a state where an appropriate tension is applied to the transport belt 5b. Further, the fixing belt 10 is rotated and moved in the direction of discharging the recording medium 2 (clockwise direction in the drawing) in a state where an appropriate tension is applied, and the pressure roller 11 and the heating roller 9 are rotated. Further, the fixing belt 10 is heated to a predetermined temperature (for example, a temperature suitable for toner fixing) by a heat generating unit (not shown) disposed inside and outside the heating roller 9.

  In this manner, in the fixing device 1, the fixing belt 10 is rotated and the pressure roller 11 and the heating roller 9 are rotated, and the surface of the fixing belt 10 is heated to a predetermined temperature. In this state, when the recording medium 2 on which the unfixed toner image T is formed is passed through the fixing nip portion N (paper passing from the right side to the left side in the drawing), the fixing nip portion N is pressed and heated. The unfixed toner image T is thermally fused on the recording medium 2 and fixed on the recording medium 2. Then, the recording medium 2 on which the toner image T is fixed is discharged from the fixing nip N, and then sent out from the fixing device 1 through a predetermined discharge path.

  Next, an example of the operation of the controller unit 16 in the fixing device 1 will be described.

  The controller unit 16 normally obtains the conveyance speed of the recording medium 2 from the detection signal from the conveyance sensor 4 and controls the rotation speeds of the fixing roller 8 and the conveyance roller 5a so that the recording medium 2 is conveyed at a predetermined speed. To do. When the first posture abnormality (curl abnormality) is detected by the posture control unit 12, the controller unit 16 widens the interval between the recording medium 2 and the recording medium 2 that are continuously conveyed to the fixing unit 3 than usual. In this way, the conveyance of the recording medium 2 is controlled. The controller unit 16 controls the conveyance of the recording medium 2 by controlling the fixing roller rotation motor 13 and the conveyance roller rotation motor 14.

  By widening the interval between the recording medium 2 and the recording medium 2 in this way, the time from when the recording medium 2 is discharged from the fixing nip N until the next recording medium 2 is inserted becomes longer. As a result, the amount of heat of the fixing roller 8 is moved to the pressure roller 11, and the temperature difference between the fixing roller 8 and the pressure roller 11 is reduced. Usually, the fixing roller 8 has a higher temperature than the pressure roller 11 and therefore tends to curl toward the fixing unit 3. In the present embodiment, when the recording medium 2 that has already been curled has been conveyed, the recording medium 2 reduces the temperature difference between the fixing roller 8 and the pressure roller 11, thereby passing the fixing nip N. The curl amount of the recording medium 2 can be reduced and discharged to the downstream side.

  When the second posture abnormality is detected by the posture control unit 12, the controller unit 16 controls the pressure roller driving unit 15 to lower the pressure applied to the pressure roller 11. Further, the controller unit 16 controls the fixing roller rotating motor 13 and the conveying roller rotating motor 14 to reduce the conveying speed of the recording medium 2 by the fixing unit 3.

  The detection of the second posture abnormality can be determined that wrinkles are generated on the recording medium 2 due to the surface pressure deviation in the width direction of the fixing nip portion N or that wrinkles are likely to occur. Further, since the central nip and the surface pressure are insufficient with respect to the width direction end portion of the fixing nip portion N, a force that excessively pulls the recording medium 2 to both ends is generated, and finally the rear end portion of the recording medium 2 is formed. It can be determined that is in a state of jumping up.

  Therefore, by reducing the pressure applied by the pressure roller 11 as described above, it is possible to reduce the surface pressure of the fixing nip portion N and reduce wrinkles and jumping of the recording medium 2 caused by the surface pressure deviation. Further, by reducing the conveyance speed of the recording medium 2, it is possible to compensate for the shortage of heat accompanying the decrease in the applied pressure.

  According to the above-described embodiment, the controller unit 16 conveys the recording medium 2 by the fixing unit 3 or the conveyance tank 5 according to the attitude of the recording medium 2 detected by the attitude detection mechanism 7 or the pressure roller 11. To control the pressure. As a result, the recording medium 2 can be transported in the correct posture, and the image quality and transportability can be improved.

  According to the above-described embodiment, the posture control unit 12 is configured to detect the first posture abnormality at the leading end of the recording medium 2 before the recording medium 2 is conveyed to the fixing unit 3, and the recording medium 2 is passing through the fixing unit 3. And a second posture abnormality upstream of the fixing unit 3 of the recording medium 2 in the transport direction. When the controller unit 16 detects the first posture abnormality or the second posture abnormality by the posture control unit 12, the controller unit 16 transports the recording medium 2 by the fixing unit 3 or the transport tank 5 or applies pressure to the pressure roller 11. change. Thereby, effective countermeasures can be taken according to the location where the lift (posture abnormality) occurs.

  According to the embodiment described above, the posture control unit 12 detects the first posture abnormality of the leading end portion of the recording medium 2 before the recording medium 2 is conveyed to the fixing unit 3. When the posture control unit 12 detects the first posture abnormality, the controller unit 16 may fix the fixing unit 3 or the conveyance unit so that the interval between the recording medium 2 and the recording medium 2 conveyed continuously to the fixing unit 3 is widened. The conveyance of the recording medium 2 by the tank 5 is controlled. Thus, even if an abnormality in the curl amount at the front end of the recording medium 2 occurs, the recording medium 2 can be conveyed in a correct posture.

  According to the above-described embodiment, the posture control unit 12 detects the second posture abnormality on the upstream side in the transport direction from the fixing unit 3 of the recording medium 2 while the recording medium 2 passes through the fixing unit 3. When the second posture abnormality is detected by the posture control unit 12, the controller unit 16 reduces the pressure applied by the pressure roller 11 and decreases the conveyance speed of the recording medium 2 by the fixing unit 3. Thereby, even if the recording medium 2 is lifted while passing through the fixing unit 3, the recording medium 2 can be conveyed in a correct posture.

  According to the embodiment described above, a plurality of posture detection mechanisms 7 are arranged side by side along the width direction orthogonal to the conveyance direction of the recording medium 2. Accordingly, any posture abnormality can be detected, for example, the end in the width direction when the curl is abnormal and the center when the recording medium 2 is bounced up.

  According to the embodiment described above, the posture detection mechanism 7 includes the spur 7a that is pushed up when the recording medium 2 is lifted and the spur rise detection sensor 7b that detects the rise of the spur 7a. Thereby, cheap and reliable detection becomes possible. Further, by using the spur 7a, it is possible to eliminate the influence on the image or to reduce it as much as possible even though it is detected by the contact method. Furthermore, image blurring to other parts located further away from the spur 7a can be prevented even for a sudden large posture abnormality.

  According to the embodiment described above, the posture detection mechanism 7 may be configured by the optical sensor 7c. In this case, the abnormality of the recording medium 2 can be detected without touching the recording medium 2 at all. Further, if the distance to the posture detection mechanism 7 can be detected, the degree of abnormality can be determined based on the distance, so that it is possible to cope with an appropriate level more quickly. Further, if a plurality of width direction array sensors are used as the optical sensor 7c, a more detailed posture of the recording medium 2 such as a one-side rise of the recording medium 2 can be detected.

(Embodiment of Image Forming Apparatus)
Hereinafter, an image forming apparatus according to an embodiment of the present invention will be described with reference to FIG.

  FIG. 8 shows the configuration of a tandem type color copier that is an image forming apparatus according to an embodiment of the present invention.

  As shown in FIG. 8, the color copying machine 200 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. And a high-speed machine having an image reading unit (not shown). In the color copying machine 200, the above-described fixing device 1 is incorporated between the image forming unit 200A and the paper feeding unit 200B and downstream of the image forming unit 200A in the sheet conveying direction.

  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, photosensitive members 205Y, 205M, 205C, and 205K as image carriers capable of carrying an image of complementary color toners (yellow Y, magenta M, cyan C, and black K) are formed on the transfer surface of the transfer belt 210. Are juxtaposed along.

  Each of the photoconductors 205Y, 205M, 205C, and 205K includes a drum that can rotate in the same direction (counterclockwise direction in the figure). For example, an optical writing device 201, a charging device 202Y, a developing device 203Y, a primary transfer device 204Y, and a cleaning device (not shown) that perform image forming processing in the rotation process are disposed around the photosensitive member 205Y. For each of the photoconductors 205M, 205C, and 205K, each device is arranged around the photoconductor 205Y.

  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 which is one of the driven rollers. The conveyance path of the recording medium 2 from the transfer roller 212 to the fixing device 1 is a horizontal path.

  The paper feed unit 200 </ b> B separates the paper feed tray 220 on which the recording medium 2 is stacked and the recording medium 2 in the paper feed tray 220 one by one in order from the top, and conveys it to the position of the transfer roller 212. A transport mechanism 221 is included.

  In forming an image in the color copying machine 200, 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. The electrostatic latent image is visualized as a toner image T by a developing device 203Y containing yellow toner, and the toner image T is transferred onto the transfer belt 210 by a primary transfer device 204Y to which a predetermined bias is applied. Next transferred. The other photoconductors 205M, 205C, and 205K also form similar images only with different toner colors, and the toner images T of the respective colors are sequentially transferred and superimposed on the transfer belt 210 by electrostatic force.

  Next, the toner image T primarily transferred onto the transfer belt 210 from the photoconductors 205Y, 205M, 205C, and 205K is transferred to the recording medium 2 conveyed by the roller 211 and the transfer roller 212. The recording medium 2 onto which the toner image T has been transferred is further conveyed to the fixing device 1 and fixed at a fixing nip N between the fixing belt 10 and the pressure roller 11. The recording medium 2 that has passed through the fixing nip N is sent out to the stacker 213 along a predetermined discharge path.

  While the present invention has been described with reference to the preferred embodiment, the present invention is not limited to the configuration of the above embodiment.

  For example, in the fixing device 1 of the above-described embodiment, when the second posture abnormality is detected, the pressing force of the pressure roller 11 is decreased and the conveyance speed of the recording medium 2 by the fixing unit 3 is decreased. It is not limited to this. For example, when the second posture abnormality is detected, the pressure applied by the pressure roller 11 may be lowered.

  In the color copying machine 200 of the above-described embodiment, a full-color tandem image forming apparatus in which a plurality of photoconductors are arranged in a row has been described. However, the present invention is not limited to this. . For example, the image forming apparatus may be a monochrome image forming apparatus having only one photoconductor or a revolver type image forming apparatus, and as long as it includes at least an image forming unit and a fixing device, as long as the object of the present invention is not violated. The configuration of the image forming apparatus is arbitrary.

  The above-described embodiments are merely representative examples of the present invention, and the present invention is not limited to the embodiments. That is, those skilled in the art can implement various modifications in accordance with conventionally known knowledge without departing from the scope of the present invention. Of course, such modifications are included in the scope of the present invention as long as the configurations of the fixing device and the image forming apparatus of the present invention are provided.

DESCRIPTION OF SYMBOLS 1 Fixing device 2 Recording medium 3 Fixing part (an example of fixing means)
5 Transport tank (an example of transport means)
7 Attitude detection mechanism (an example of attitude detection means)
7a Spur 7b Spur rise detection sensor 7c Optical sensor 8 Fixing roller 11 Pressure roller 12 Attitude control unit (an example of attitude detection means)
16 Controller (an example of control means)
200 Image forming apparatus 200A Image forming unit T Toner image

JP-A-63-313182 Japanese Patent Laid-Open No. 1-263679 Japanese Utility Model Publication No. 51-109739 JP-A-5-297863

Claims (6)

A toner image on the recording medium having a fixing roller to be heated and a pressure roller for pressing the fixing roller, and conveying the recording medium between the fixing roller and the pressure roller. A fixing device comprising: fixing means for fixing the recording medium; and conveying means for conveying the recording medium to the fixing means,
Attitude detection means for detecting the attitude of the recording medium upstream of the fixing means in the transport direction;
Control means for controlling the conveyance of the recording medium by the fixing means or the conveying means or the pressure applied by the pressure roller according to the attitude detected by the attitude detecting means ,
The posture detection means detects a first posture abnormality that is a lift in the thickness direction of the recording medium that occurs at the leading end of the recording medium before the recording medium is transported to the fixing means;
When the first attitude abnormality is detected by the attitude detection means, the control means increases the interval between the recording medium and the recording medium conveyed continuously to the fixing means. A fixing device that controls conveyance of the recording medium by the conveyance unit. The posture detection unit detects a second posture abnormality that is a lift in the thickness direction of the recording medium upstream of the fixing unit of the recording medium while the recording medium passes through the fixing unit;
When the second posture abnormality is detected by the posture detection unit, the control unit lowers the pressing force of the pressure roller and decreases the conveyance speed of the recording medium by the fixing unit. The fixing device according to claim 1 . It said posture detecting means, the fixing device according to claim 1 or 2, characterized in that it is arranged more along the width direction perpendicular to the conveying direction of the recording medium. It said posture detecting means, the fixing device according to any one of claim 1 to 3, wherein the composed spur rise sensor for detecting the rise of the spur and the spur pushed up and the recording medium from floating. It said posture detecting means, the fixing device according to any one of claim 1 to 4, characterized in that and an optical sensor. An image forming unit for forming a toner image on a recording medium;
A fixing device according to any one of claim 1 to 5 for fixing the toner image formed on the recording medium by said image forming unit on the recording medium,
An image forming apparatus comprising:

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