JP2005164895A - Fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device and an image forming apparatus, provided with the fixing device by which defective separation of sheets or the like can be quickly detected and the defective carrying of sheets can be prevented. <P>SOLUTION: The fixing device for carrying a sheet on which an unfixed image is formed, while nipping the sheet by a pair of rollers 50, 60, heating the sheet and fixing the unfixed image is provided with a fixing separation claw 54 for abutting against at least one of the rollers 50, 60 and a jam detection sensor lever 55, integrally formed with the fixing separation claw 54 to detect the defective carrying of the sheet. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fixing device for fixing an unfixed image by conveying and heating a sheet on which an unfixed image is formed by a nip pair of rotating bodies in an electrophotographic copying machine, a laser printer, or the like. And an image forming apparatus including the same.

  Conventionally, an image forming apparatus such as a laser beam printer forms a latent image with a laser beam on the surface of a photosensitive drum, and develops the latent image with a developing device to transfer a visible toner image onto a recording material. Form an image. Since the transferred toner image is in an unfixed state, the recording material is conveyed to a fixing device and fixed by heating.

  Various types of fixing devices have been developed today, and heat and pressure are applied while the recording material is conveyed through the nip by a pair of rotating rollers composed of a fixing roller and a pressure roller having a heater built therein. There is a heat roller system that fixes by doing so.

  FIG. 13 is a cross-sectional explanatory view showing an example of a heat roller type fixing device. In FIG. 13, reference numeral 31 denotes a fixing inlet guide, which is provided to guide the recording material after transfer to the fixing nip.

  Reference numeral 50 denotes a fixing roller. As an example, a releasable resin layer 52 such as PFA or PTFE is provided on a core metal 51 such as aluminum or iron, and the inside is heated by a heater 53. The temperature of the fixing roller 50 is detected as the surface temperature of the fixing roller 50 by the temperature detecting element 34 in contact with the fixing roller 50, and the surface temperature is determined by intermittently operating the heater 53 by the temperature control circuit. It is controlled to a predetermined temperature. Reference numeral 54 denotes a fixing separation claw, which is in contact with the fixing roller with a predetermined pressing force. A plurality of fixing separation claws 54 are provided in the longitudinal direction so as to correspond to various recording material sizes, and serve to prevent the recording material from being wound around the fixing roller.

  On the other hand, 60 is a pressure roller that presses and rotates against the fixing roller 50. As an example, an elastic material such as silicon rubber or silicon sponge having heat resistance and low hardness on a metal core 61 such as aluminum or iron. A layer 62 is provided, and a structure having a coating layer 63 made of a conductive PFA resin added with carbon on the surface thereof is formed. A pressure separation guide 64 plays a role of preventing the recording material from being wound around the pressure roller 60.

  With this pair of rollers, the recording material on which fixing has been completed is conveyed by the fixing discharge roller 70. At this time, as shown in FIG. 14, the discharge sensor lever 32 installed at the center of the sheet conveyance area records the recording material. The discharge sensor 33 is cut off by being pushed in the direction of the arrow by the material P and shielded between the discharge sensors 33 by a lever installed in the non-sheet conveyance area interlocked by the drive transmission shaft. Conventionally, the ON / OFF timing of the discharge sensor is measured according to the length of the recording material and the distance between the sheets, and the occurrence of fixing jam (sheet jam) is detected.

  That is, if the discharge sensor 33 does not turn ON or OFF at a predetermined timing, it is assumed that the recording material remains in the fixing device, and the rotation of the roller is immediately stopped by a control unit (not shown), and the jam is detected. Inform the user of the occurrence. As this fixing jam, there is mainly a poor separation from a roller when a recording material with weak stiffness is conveyed. If the recording material adheres to the fixing roller 50 or the pressure roller 60 and the separation is delayed, the recording material cannot cut the discharge sensor at a predetermined timing, resulting in a fixing delay jam. The discharge sensor 33 detects a jam due to such a poor separation of the recording material from the roller.

JP 2000-344395 A

  However, the fixing device having the above configuration has the following problems.

  If an image with a high printing rate is formed on the leading edge of the recording material, or if the recording material with weak stiffness absorbs moisture in a high humidity environment and the curl amount is particularly large, the fixing separation claw 54 or the pressure separation guide 64 is used. Even if the recording material is provided, the recording material digs under the roller contact member and is wound around the fixing roller 50 shown in FIG.15 (a) and wound around the pressure roller 60 shown in FIG.15 (b). May occur. Then, as the amount of the recording material that is squeezed under the roller contact member increases, the jam processing becomes more difficult for the user.

  Also, if the leading edge of the recording material is wound around the roller, the trailing edge of the recording material is only slightly out of the fixing device, so that the user remains in the image forming apparatus even if a jam is notified. It is difficult to find the recording material that is being used. For this reason, even when the user opens the exterior member of the image forming apparatus, the roller winding jam may not be noticed, and the exterior member may be closed again or the image forming apparatus may be turned on again.

  If the exterior member of the image forming apparatus is closed or the power is turned on again with the leading edge of the recording material wrapped around the roller, the fixing / ejection sensor lever 32 is not pressed by the recording material, so that a fixing jam can be detected. Can not. Accordingly, it is considered that there is no remaining sheet in the fixing device, and warming up of the fixing device before printing is started. That is, after the heater is turned on, the roller is driven to rotate until the fixing roller 50 reaches a predetermined temperature. Due to the rotational driving of the roller, the recording material is caught in the pressure roller 60 shown in FIG. 16A, and the recording material does not come out of the fixing device, so that the user cannot find it. If the apparatus continues to be used in this state, not only the printed recording material will be wrinkled, but also the fixability will deteriorate, and the inside of the fixing apparatus will be contaminated by the offset toner.

  Even when the recording material is caught by the central portion of the fixing separation claw 54, it is determined that there is no remaining sheet in the fixing device because the central portion of the recording material does not press the discharge sensor lever 32. Therefore, after the heater is turned on, the roller is driven to rotate, and the recording material is discharged from the fixing nip, but both ends of the recording material are transported first, and the leading edge of the recording material does not bite into the discharge roller 70. As shown in FIG. 16 (b), the recording material stays in a folded state in the gap immediately after the fixing nip. In such a state, the recording material blocks the conveyance path between the fixing nip and the fixing discharge roller 70, and jamming occurs again in the next recording material printing. There is also a risk that the roller contact member such as the fixing separation claw is strongly pressed by the recording material staying in a folded state, and the roller surface is damaged.

  Further, with the conventional configuration, the fixing discharge sensor lever 32 is attached as a separate component from the fixing separation claw 54, which increases the cost.

  SUMMARY An advantage of some aspects of the invention is that it provides a fixing device that quickly detects a sheet separation failure and the like and does not have a conveyance failure, and an image forming apparatus including the fixing device. Specifically, it is possible to quickly detect a separation failure such as the leading edge of the recording material getting under the roller contact member. In addition, it is detected that the recording material is caught in the pressure roller and caught in the center of the fixing separation claw, and the recording material is wrinkled, the fixing property is deteriorated, the contamination in the fixing device and the roller damage are removed. The purpose is to prevent. Furthermore, it aims at reducing cost by reducing the number of parts of a jam detection mechanism.

  The first means in the present invention for solving the above-described problems is a fixing device for fixing the unfixed image by conveying the sheet on which the unfixed image is formed in a nipped state by a pair of rotating bodies and heating the sheet. And a contact member that is in contact with at least one of the rotating bodies of the pair of rotating bodies, and a detection member that is integrally formed with the contact member and that detects a sheet conveyance failure. To do.

  According to a second means, in the first means, the detection member operates in accordance with a conveyance state of the sheet, and detects a conveyance failure of the sheet by detecting an operation state of the detection member by a detection sensor. It is characterized by.

  According to a third means, in the second means, the detection member integrally includes a first protrusion located in the sheet conveyance region and a second protrusion located outside the sheet conveyance region, The second protrusion is detected by the detection sensor.

  The fourth means operates in the second or third means when the detection member is pushed by the leading edge of the conveyed sheet and when the trailing edge of the sheet passes the detection member, and the detection sensor A sheet conveyance failure is detected by measuring a timing at which the detection member is detected.

  A fifth means is that, in the second or third means, the detection member is operated by being pushed by a conveyed sheet, and the detection sensor detects the operated detection member for a predetermined time or more. It is characterized in that it is determined that the sheet conveyance is defective.

  A sixth means is characterized in that, in the first means, the contact member is a separation claw for separating the sheet conveyed by the rotating body from the rotating body.

  A seventh means is characterized in that, in the first means, the detection member is constituted by a plurality of parts.

  In an image forming apparatus that forms an unfixed image on a conveyed sheet and conveys the sheet to a fixing device to fix the unfixed image, the eighth means includes any one of the first to seventh as the fixing device. It is characterized in that a fixing device is provided.

  According to the present invention, by providing the detection member integrally with the contact member that contacts the rotating body, jam detection by the sensor is performed immediately after the sheet passes through the rotating body, and rapid jam detection becomes possible. . Therefore, by immediately detecting the separation failure of the sheet from the rotating body, it is possible to easily prevent the rotating body from being damaged by the contact member and to perform jam processing by the user. Further, by integrating the contact member and the detection member for jam detection, the number of parts can be reduced and the cost can be reduced.

  Next, an embodiment of a fixing device according to the present invention and an image forming apparatus including the fixing device will be specifically described.

[First Embodiment]
FIG. 1 is a schematic cross-sectional explanatory diagram of an image forming apparatus including a fixing device according to a first embodiment of the present invention with reference to FIGS. 1 to 6.

{Image forming device}
First, the overall configuration of an image forming apparatus including a fixing device will be briefly described. FIG. 1 is an explanatory sectional view of the image forming apparatus according to the first embodiment. In the figure, a printer main body (image forming apparatus main body) includes a laser scanner 10, a photosensitive drum 11, a process cartridge 15 including a primary charger 12 and a developing roller 13, a transfer roller 16, a fixing device 30, and a conveying roller pair. 18. A feeding cassette 20 and a feeding roller (including a pickup roller) 21 are installed.

  The sheet-like recording material P stacked and stored in the feeding cassette 20 is fed by a feeding roller 21 that rotates counterclockwise, and is guided to a conveying sheet metal 22 to be sent to the nip portion of the conveying roller pair 18. It is done.

  Next, the recording material P is sent between the photosensitive drum 11 and the transfer roller 16 by the conveying roller pair 18. The photosensitive drum 11 rotates clockwise and is uniformly charged by the primary charger 12. Then, an electrostatic latent image is sequentially formed on the outer peripheral surface by the laser light L of the laser scanner 10, and then the electrostatic latent image is developed by the developing roller 13 to form a toner image. The toner images on the photosensitive drum 11 are sequentially transferred from the transfer roller 16 to the recording material P sent between the photosensitive drum 11 and the transfer roller 16. The recording material P onto which the toner image has been transferred in this manner is sent to the fixing device 30, where it is heated and pressurized to fix the toner image on the recording material P. Thereafter, the recording material P is sent to the discharge roller 81 by the fixing discharge roller 70 and then discharged onto the discharge tray 80 on the upper surface of the printer main body by the discharge roller 81.

{Fusing device}
Next, the fixing device according to this embodiment will be described. FIG. 2 is an explanatory cross-sectional view of the fixing device according to the present embodiment. The fixing device according to the present embodiment is an example of a center reference that transports a recording material P having an A3 size (297 mm) width as a maximum transport size with reference to the recording material transport center of the device. The heater output is symmetrical with respect to the sheet conveyance reference. A fixing inlet guide 31 is provided to guide the recording material P after transfer to the fixing nip. The recording material is nipped and conveyed by a pair of rotating members of a fixing roller 50 and a pressure roller 60, which are rotating members, and an unfixed toner image is fixed by heating and pressing.

  The fixing roller 50 according to the present embodiment is a roller having a diameter of 50 mm and a thickness of 3.0 mm using aluminum as a metal core 51, and a PFA release layer 52 is coated on the surface layer. Reference numeral 54 denotes a fixing separation claw as an abutting member, which promotes the separation of the recording material P from the fixing roller 50 by contacting the fixing roller 50 with a pressing force of 0.1 N at six positions in the longitudinal direction. ing. The temperature of the fixing roller 50 is detected as the surface temperature of the fixing roller 50 by the temperature detecting element 34 in contact with the end of the fixing roller, and the surface temperature is increased by intermittently operating the heater 53 by the temperature control circuit. Is controlled to a predetermined temperature.

  The pressure roller 60 has a silicon sponge elastic layer 62 on a stainless steel core 61 and a PFA release layer 63 on the surface layer. The pressure roller 60 has a diameter of 40 mm and a product hardness of 60 °, and applies a pressure of 500 N. As a result, a nip width of 7.0 mm between the fixing roller 50 and the fixing roller 50 can be formed. Reference numeral 64 denotes a pressure separation guide, which is brought into contact with two places in the longitudinal direction of the pressure roller by its own weight and serves to prevent the recording material P from being wound around the pressure roller 60.

  The recording material P that has been fixed by the pair of rollers is conveyed by the fixing discharge roller 70. The process speed is 240 mm / sec. With this configuration, printing at 50 sheets / min is possible with A4 horizontal feed.

  FIG. 3 shows a schematic diagram in the longitudinal direction of the roller. Fixing separation claws 54 are in contact with the recording material conveyance area at six equal intervals, and a temperature detection element 34 is in contact with the end. In the present embodiment, a jam detection sensor lever 55, which is a detection member for detecting a jam, is provided on the fixing separation claw 54 at the center. When the leading edge of the recording material P passes through the fixing nip and pushes the jam detection sensor lever 55, the fixing separation claw 54 rotates around the fulcrum 56 in the direction of the arrow in FIG.

  At this time, as shown by a broken line in FIG. 2, the sensor lever 55 moves to the position of the optical transmission type jam detection sensor 57 and shields light between the sensors 57, thereby turning off the sensor and recording. It is determined that the leading end of the material is separated by the fixing separation claw 54. Thereafter, the leading edge of the recording material bites into the discharge roller 70, and the recording material P is discharged out of the image forming apparatus. When the trailing end of the recording material passes through the fixing nip and passes the position of the sensor lever 55, the sensor lever 55 is hooked on a fixing separation claw support member (not shown), and the fixing separation claw 54 is fixed to the fixing roller 50 with a pressing force of 0.1N. It returns to its original position by the force of the spring in contact with the. At this time, the jam detection sensor 57 determines that the gap is not shielded by the sensor lever 55, the sensor 57 is turned on again, and the recording material P passes through the discharge roller 70 without staying in the fixing device.

  In this way, the occurrence of fixing jam is detected by measuring the ON / OFF timing of the jam detection sensor 57 in accordance with the length of the recording material and the distance between sheets. If the jam detection sensor 57 does not turn OFF at a predetermined timing, the leading edge of the recording material is poorly separated, and the leading edge of the recording material sinks under the fixing separation claw 54 as shown in FIG. Or the leading edge of the recording material may be wound around the pressure roller 60 as shown in FIG.

  If the jam detection sensor 57 does not turn on at a predetermined timing, as shown in FIG. 5, the sheet is jammed in the fixing device, and the recording material is sent out from the discharge roller 70 to the outside of the fixing device. The case where it was not possible is considered.

  Therefore, when the jam detection sensor 57 does not turn ON or OFF at a predetermined measurement timing, or when the detection sensor 57 detects the jam detection sensor lever 55 for a predetermined time or more (when it is OFF), the inside of the fixing device In this case, it is assumed that the recording material remains, and the rotation of the roller and the energization to the heater 53 are immediately stopped by a control unit (not shown). At the same time, an operator operation panel (not shown) notifies the user that the recording material remains in the fixing device and warns the user to perform appropriate processing.

  Further, the same effect can be obtained by providing a saddle-shaped jam detection sensor lever 55 as shown in FIG.

  Thus, by providing the jam detection sensor lever 55 on the fixing separation claw 54, the fixing separation claw 54 is separated from the fixing roller 50 immediately after the recording material is separated, and the sensor lever cuts the jam detection sensor 57. It is possible to detect jam more quickly than the discharge sensor. In addition, by integrating the fixing separation claw 54 and the jam detection sensor lever 55, the number of parts is reduced, leading to cost reduction.

[Second Embodiment]
In the second embodiment, an example in which a separation lever and a jam detection lever are provided on the fixing separation claw will be described. In the configuration of the fixing device in the present embodiment, the description of the same parts as those in the first embodiment described above is omitted.

  FIG. 7 shows a cross-sectional view of the fixing device according to the present embodiment. In this embodiment, as in the case of the first embodiment, a separation lever 58 as a first protrusion and a jam detection lever 59 as a second protrusion are provided on the fixing separation claw at the center. The separation lever 58 is located in the recording material conveyance area, and the jam detection lever 59 is located outside the recording material conveyance area.

  When the leading edge of the recording material P passes through the fixing nip and pushes the separation lever 58, the fixing separation claw 54 rotates in the direction of the arrow about the fulcrum 56. At the same time, as indicated by a broken line in FIG. 7, the jam detection lever 59 moves to the position of the optical jam detection sensor 57 to shield the light between the sensors 57, so that the sensor 57 is turned OFF and recording is performed. It is determined that the leading end of the material is separated by the fixing separation claw 54.

  Thereafter, the leading edge of the recording material bites into the discharge roller 70, and the recording material is discharged out of the image forming apparatus. When the trailing edge of the recording material passes through the fixing nip and passes the position of the separation lever 58, the separation lever 58 is hooked on a fixing separation claw support member (not shown), and the fixing separation claw is fixed with a pressing force of 0.1 N. It returns to its original position by the force of the spring that is in contact with the roller. At the same time, the jam detecting lever 59 also returns to the original position. The jam detection sensor 57 determines that the gap is not shielded by the jam detection lever 59, the sensor 57 is turned on again, and the recording material P passes through the discharge roller 70 without staying in the fixing device.

  If the jam detection sensor does not turn ON or OFF at a predetermined timing according to the length of the recording material or the distance between the sheets, it is assumed that the recording material remains in the fixing device, and the control unit (not shown) immediately Stop rotating the roller and energize the heater. At the same time, an operator operation panel (not shown) notifies the user that the recording material remains in the fixing device and warns the user to perform appropriate processing.

  Thus, by providing the separation lever 58 and the jam detection lever 59 on the fixing separation claw 54, the separation lever 58 is separated from the fixing roller 50 by the separation lever 58 immediately after the recording material is separated, and at the same time, jam detection is performed. Since the lever 59 cuts the jam detection sensor 57, it is possible to detect the jam more quickly than the conventional discharge sensor. In addition, since the separating lever 58 can be installed at a position where the leading edge of the recording material passes reliably, more accurate jam detection can be performed. Furthermore, by integrating the fixing separation claw 54 and the jam detection lever 59, the number of parts is reduced, leading to a cost reduction. It is also possible to arrange the jam detection sensor 57 outside the recording material conveyance area.

[Third Embodiment]
In 3rd Embodiment, the example in the case of providing a jam detection sensor in a pressurization isolation | separation guide is shown. In the configuration of the fixing device in the present embodiment, the description of the same parts as those in the first embodiment described above is omitted.

  FIG. 8 is a sectional view of the fixing device according to the present embodiment. FIG. 9 shows a schematic diagram in the longitudinal direction of the roller. In the present embodiment, a jam detection lever 65 is provided in the pressure separation guide 64 in addition to the fixing separation claw 54. The effect of the jam detection lever 55 provided on the fixing separation claw 54 is as described in the first embodiment. The recording material remaining in the fixing device that cannot be detected by the jam detection mechanism provided in the fixing separation claw 54 as described in (1) to (2) below is detected by the jam detection lever 65 provided in the pressure separation guide 64. Can do.

  (1) When the recording material is wound on the pressure roller side

  As shown in FIG. 10A, when the rear end of the recording material pushes the pressure separation guide 64, the pressure separation guide 64 is tilted about the fulcrum 66 in the direction of the arrow. At this time, the jam detection lever 65 falls to the position of the optical jam detection sensor 67 as shown in the figure to shield the light between the sensors 67, so that the sensor 67 is turned OFF and the recording material remains in the fixing device. Judge that you are doing.

  (2) When the recording material is caught in the center of the fixing separation claw

  As shown in FIG. 10 (b), when the recording material staying in the folded state presses the pressure separation guide 64, the pressure separation guide 64 falls down in the direction of the arrow about the fulcrum 66. Yes. At this time, the jam detection lever 65 falls to the position of the optical jam detection sensor 67 as shown in the figure to shield the light between the sensors 67, so that the sensor 67 is turned OFF and the recording material remains in the fixing device. Judge that you are doing.

  When the recording material remaining in the fixing device is detected as in the above (1) to (2), the sensor 67 is turned on even if the exterior member of the image forming apparatus is closed or the power is turned on again. Otherwise, that is, unless the user removes the recording material remaining in the fixing device and returns the pressure separation guide 64 in the fixing device to the original position, the roller is not rotated and the heater is not energized.

  At this time, an operator operation panel (not shown) notifies the user that the recording material remains in the fixing device, and instructs the user to remove the recording material and return the pressure separation guide 64 to the original position. After the user performs the above operation, the jam detection sensor 67 determines that the gap is not shielded by the jam detection lever 65, the sensor 67 is turned on, and no recording material remains in the fixing device.

  Thus, by providing a jam detection member in the pressure separation guide 64, it is possible to detect the recording material staying in the fixing device without turning off the sensor provided on the fixing separation claw side. It is possible to prevent the material from being wrinkled, the fixing property from being lowered, the dirt in the fixing device and the roller damage.

[Fourth Embodiment]
In the fourth embodiment, an example in which a jam detection sensor lever is provided in a separation claw holder attached to a fixing separation claw will be described. In the configuration of the fixing device in the present embodiment, the description of the same parts as those in the first embodiment described above is omitted.

  FIG. 11 is a sectional view of the fixing device according to the present embodiment. In the present embodiment, the separation claw holder 35 is provided outside the fixing separation claw 54. As shown in the perspective view of FIG. 12, this separation claw holder 35 is attached to the outside of the fixing separation claw 54, and the recording material remaining in the fixing device presses the fixing separation claw 54 to cause roller damage. Is prevented. That is, even if the fixing separation claw 54 is strongly pressed to the fixing roller side by the recording material, the fixing separation claw 54 is pushed upward by the separation claw holder 35 and the tip of the separation claw 54 is separated from the fixing roller 50. As a result, no pressing force is applied to the fixing roller.

  In the present embodiment, the separation claw holder 35 is attached to all the fixing separation claws 54 that are in contact with the six fixing roller longitudinal directions, and the optical separation is provided at the position of the separation claw holder 35 attached to the fixing separation claw 54 in the center. A type jam detection sensor 57 is provided. When the leading edge of the recording material P passes through the fixing nip and pushes the jam detection sensor lever 36, the separation claw holder 35 rotates around the fulcrum 56 in the direction of the arrow in FIG.

  At this time, the fixing separation claw 54 is also rotated in the same direction by the separation claw holder 35 and separated from the fixing roller 50. At the same time, as indicated by a broken line in FIG. 11, the jam detection sensor lever 36 moves to the position of the jam detection sensor 57 and shields light between the sensors 57, so that the sensor 57 is turned OFF and the leading edge of the recording material is It is determined that the image is separated by the fixing separation claw 54. Thereafter, the leading edge of the recording material bites into the discharge roller 70, and the recording material is discharged out of the image forming apparatus.

  When the trailing edge of the recording material passes through the fixing nip and passes the position of the jam detection sensor lever 36, the sensor lever 36 is caused by the spring force that contacts the fixing roller 50 with a pressing force of 0.1 N on the fixing separation claw 54. It returns to the original position together with the fixing separation claw 54. As a result, the jam detection sensor 57 is not shielded by the jam detection sensor lever 36, the sensor 57 is turned on again, and it is determined that the recording material P has passed through the discharge roller 70 without staying in the fixing device.

  If the jam detection sensor does not turn ON or OFF at a predetermined timing according to the length of the recording material or the distance between the sheets, it is assumed that the recording material remains in the fixing device, and the control unit (not shown) immediately Stop rotating the roller and energize the heater. At the same time, an operator operation panel (not shown) notifies the user that the recording material remains in the fixing device and warns the user to perform appropriate processing.

  In this way, by providing the jam detection sensor lever 36 on the separation claw holder 35 attached to the fixing separation claw 54, the fixing separation claw 54 is prevented from being damaged by the fixing separation claw 54 and immediately after the recording material is separated. Since the sensor lever 36 cuts the jam detection sensor 57 away from the fixing roller 50, it is possible to detect the jam more quickly than the conventional discharge sensor. Further, by integrating the separation claw holder 35 and the jam detection sensor lever 36, the number of parts is reduced, leading to a cost reduction.

[Other Embodiments]
As described above, in the first to fourth embodiments, the jam detection sensor is installed near the fixing separation member. However, since this installation location is a recording material conveyance area near the fixing roller and the pressure roller, the following problems may occur. That is, (1) it may be difficult to secure a sufficient space for installing the sensor. (2) There is a possibility of exceeding the heat resistance temperature of the sensor due to temperature rise. (3) There is a possibility that toner or paper dust adheres to the sensor and erroneously detects.

  When the above problem occurs, the jam detection sensor may be installed away from the roller. For example, as described in the prior art, a drive transmission shaft that interlocks with the jam detection sensor lever of the fixing separation member is provided, and the lever installed in the non-sheet conveyance area turns the jam detection sensor ON / OFF. Configuration etc. can be considered.

1 is a cross-sectional view of an image forming apparatus according to a first embodiment. 1 is a cross-sectional view of a fixing device showing a first embodiment. It is a figure which shows the longitudinal positional relationship of the contact member of the roller in 1st Embodiment. It is a figure which shows the method of detecting the leading end separation defect of the recording material in 1st Embodiment. FIG. 3 is a diagram illustrating a method for detecting a fixing device stay in a recording material in the first embodiment. It is a figure which shows the modification of 1st Embodiment. FIG. 6 is a cross-sectional view of a fixing device showing a second embodiment. FIG. 9 is a cross-sectional view of a fixing device showing a third embodiment. It is a figure which shows the longitudinal positional relationship of the contact member of the roller in 3rd Embodiment. FIG. 10 is a diagram illustrating a method for detecting a remaining sheet in a fixing device according to a third embodiment. FIG. 9 is a cross-sectional view of a fixing device showing a fourth embodiment. It is a perspective view of the separation claw holder in a 4th embodiment. It is sectional drawing of the conventional fixing device. It is a figure explaining the operation | movement method of a discharge sensor. It is a figure which shows the roller winding jam of a recording material. FIG. 6 is a diagram illustrating recording material fixing device retention.

Explanation of symbols

L: Laser beam P: Recording material
10 ... Laser scanner
11… Photoreceptor drum
12… Primary charger
13 ... Developing roller
15 Process cartridge
16 Transfer roller
18… Conveying roller pair
20 ... Feed cassette
21… feed roller
22… Conveyance sheet metal
30… Fixer
31… Fixing entrance guide
32… Discharge sensor lever
33… discharge sensor
34… Temperature sensing element
35… Separation claw holder
36… Jam detection sensor lever
50… Fixing roller
51… Core
52… Releasable resin layer
53… Heater
54… fixing separation nail
55… Jam detection sensor lever
56… fulcrum
57… Jam detection sensor
58… Lever for separation
59… Jam detection lever
60… Pressure roller
61… Metal cored bar
62… Elastic layer
63… Coating layer
64… Pressure separation guide
65… Jam detection lever
66… fulcrum
67… Jam detection sensor
70… Fixing discharge roller
80… discharge tray
81… discharge roller

Claims (8)

In the fixing device for fixing the unfixed image by conveying the sheet on which the unfixed image is formed by being nipped by a pair of rotating bodies and heating the sheet,
A contact member that contacts at least one of the rotating bodies of the pair of rotating bodies;
A detection member that is integrally formed with the contact member and detects a sheet conveyance failure;
A fixing device. The fixing device according to claim 1, wherein the detection member operates according to a conveyance state of the sheet, and detects a conveyance failure of the sheet by detecting an operation state of the detection member by a detection sensor. The detection member integrally includes a first protrusion located in the sheet conveyance area and a second protrusion located outside the sheet conveyance area, and the detection sensor detects the second protrusion. The fixing device according to claim 2, wherein: The detection member operates when the leading edge of the sheet to be conveyed is pressed and when the trailing edge of the sheet passes the detection member, and detects the sheet conveyance failure by measuring the timing at which the detection sensor detects the detection member. The fixing device according to claim 2, wherein the fixing device is detected. The detection member is operated by being pushed by a conveyed sheet, and when the detection sensor detects the operated detection member for a predetermined time or more, it is determined that the sheet conveyance is defective. Item 4. The fixing device according to Item 3. The fixing device according to claim 1, wherein the contact member is a separation claw for separating a sheet conveyed by the rotating body from the rotating body. The fixing device according to claim 1, wherein the detection member includes a plurality of parts. In an image forming apparatus that forms an unfixed image on a conveyed sheet, conveys the sheet to a fixing device, and fixes the unfixed image.
An image forming apparatus comprising the fixing device according to claim 1 as the fixing device.

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