JP2023078553A - Fixing device and image forming apparatus - Google Patents

Abstract

To easily remove a medium that has caused paper jam in a fixing device.SOLUTION: A fixing device 1 has: a fixing roller 11 that is used for heating a medium P; a pressure roller 12 that is brought into pressure contact with the fixing roller 11 and forms, with the fixing member 11, a nip part N through which the medium P to be conveyed passes; and a rear guide 22 that is provided on the downstream side of the nip part N in a conveyance direction of the medium P, and is movable between a guide position where it guides the medium P to be conveyed and a retracted position where it is retreated from the guide position. The rear guide 22 has ribs 23, 24 as locking parts each having at least one of a projection A and a recess B in the conveyance direction of the medium P. With the movement of the rear guide 22 from the guide position to the retracted position, the locking parts move to the downstream side in the conveyance direction.SELECTED DRAWING: Figure 12

Description

The present disclosure relates to a fixing device that fixes an image on a medium, and an image forming apparatus that includes the fixing device.

An image forming apparatus using an electrophotographic process includes a fixing device that applies heat and pressure to an image (toner image) transferred onto a medium to fix the image onto the medium. A fixing device forms a nip portion with a fixing member and a pressure member, applies heat and pressure to a medium passing through the nip portion, and fixes an image to the medium.

Japanese Patent Application Laid-Open No. 2002-200002 discloses a fixing device that includes a rotatable guide member downstream of the nip portion in the medium conveying direction. The guide member is rotatable between a guide position for guiding the medium and a retracted position retracted from the guide position. When a medium jam occurs, the guide member is moved to the retracted position, and the jammed medium is removed while the fixing member is exposed.

JP 2017-156486 A (paragraphs 0065 to 0067, see FIGS. 7 and 8)

However, the conventional fixing device has a problem that the work of removing the jammed medium from the fixing device is complicated.

The present disclosure has been made to solve the above problems, and aims to make it easier to remove jammed media.

A fixing device according to the present disclosure includes: a fixing member used for heating a medium; a pressing member that is pressed against the fixing member and forms a nip portion between the fixing member and the fixing member through which the medium to be conveyed passes; It has a guide member that is provided on the downstream side of the nip portion in the direction and is movable between a guide position that guides the conveyed medium and a retracted position that retracts from the guide position. The guide member has an engaging portion that has at least one of a convex portion and a concave portion in the medium transport direction. As the guide member moves from the guide position to the retracted position, the engaging portion moves downstream in the transport direction.

According to the present disclosure, when the guide member is moved from the guide position to the retracted position, the locking portion of the guide member moves downstream in the conveying direction. pushed downstream. Therefore, it is possible to easily remove the medium from the fixing device.

1 illustrates the configuration of an image forming apparatus according to a first embodiment; FIG. 2 is a cross-sectional view showing the structure of the fixing device according to the first embodiment; FIG. 1 is a perspective view showing the appearance of a fixing device according to a first embodiment; FIG. 1 is a perspective view showing the appearance of a fixing device according to a first embodiment; FIG. It is a perspective view showing the guide member of the first embodiment. It is a figure which shows the guide member of 1st Embodiment, and its periphery. FIG. 4 is a cross-sectional view showing a state in which a guide member of the fixing device according to the first embodiment is rotated to a retracted position; 4 is a cross-sectional view showing a state in which the guide member of the fixing device according to the first embodiment is slightly rotated from the guide position; FIG. 3 is a cross-sectional view showing a state in which the nip portion of the fixing device of the first embodiment is opened; FIG. 2 is a block diagram showing a control system of the image forming apparatus according to the first embodiment; FIG. 4A and 4B are schematic diagrams for explaining a jammed medium removing operation in the fixing device according to the first embodiment; FIG. 4A and 4B are schematic diagrams for explaining a jammed medium removing operation in the fixing device according to the first embodiment; FIG. 4A and 4B are diagrams showing the relationship between the guide member and the reference transport surface of the medium according to the first embodiment; FIG. FIG. 10 is a diagram illustrating the configuration of a fixing device according to a second embodiment; FIG. 11 is a perspective view showing a guide member and holding ribs of a second embodiment; FIG. 10 is a schematic diagram showing a configuration example for positioning the sandwiching ribs of the second embodiment; 10A and 10B are schematic diagrams showing the jammed medium removing operation in the fixing device of the second embodiment; FIG. FIG. 10 is a diagram illustrating the configuration of a fixing device according to a third embodiment; FIG. 10 is a diagram illustrating the configuration of a fixing device according to a third embodiment; FIG. 11 is a schematic diagram showing a configuration example of a transmission mechanism according to a third embodiment; 10A and 10B are schematic diagrams showing the jammed medium removing operation in the fixing device of the third embodiment; FIG. FIG. 10 is a diagram illustrating the configuration of a fixing device according to a fourth embodiment; FIG. 10 is a diagram illustrating the configuration of a fixing device according to a fourth embodiment; FIG. 10 is a diagram illustrating the configuration of a fixing device according to a fifth embodiment; FIG. FIG. 10 is a diagram illustrating the configuration of a fixing device according to a fifth embodiment; FIG.

First embodiment.
<Image forming apparatus>
First, the image forming apparatus 2 of the first embodiment will be described. FIG. 1 is a diagram showing an image forming apparatus 2. As shown in FIG. The image forming apparatus 2 is a printer that forms an image using an electrophotographic process.

The image forming apparatus 2 includes a medium supply unit 6 that supplies a medium P such as printing paper, an image forming unit 5 that forms an image on the medium P, a fixing device 1 that fixes an image on the medium P, and a medium P that is ejected. and a medium ejection unit 7 for carrying out. These components are housed in the housing 2A.

The medium supply section 6 has a medium cassette 60 , a pickup roller 61 , a feed roller 62 , a retard roller 63 , registration rollers 65 and transport rollers 66 .

The medium cassette 60 is a cassette that accommodates a medium P such as printing paper, and has a holding plate 60a on which the medium P is placed. The pickup roller 61 feeds out the media P in the media cassette 60 one by one. The feed roller 62 and the retard roller 63 separate the fed medium P one by one and send it out to the transport path 64 . The registration rollers 65 correct the skew of the medium P sent to the transport path 64 and further transport the medium. The transport roller 66 transports the medium P to the image forming unit 5 .

The image forming unit 5 has a photosensitive drum 51 as an image carrier. An exposure head 53 as an exposure device is arranged so as to face the photosensitive drum 51 . The exposure head 53 has an LED array in which LEDs (light emitting diodes) as light emitting elements are arranged and a lens array, and irradiates the surface of the photosensitive drum 51 with light. The exposure head 53 is suspended and supported by a top cover 2B that covers the upper portion of the housing 2A.

The image forming unit 5 includes the photosensitive drum 51, a charging roller 52 as a charging member, a developing roller 54 as a developer carrier, a supply roller 55 as a supply member, and a toner container as a developer container. a cartridge 56;

The photoreceptor drum 51 is a cylindrical member having a photosensitive layer formed on the surface of a conductive support, and rotates clockwise in the figure. The photosensitive drum 51 carries an electrostatic latent image on its surface.

The charging roller 52 is arranged to contact the surface of the photoreceptor drum 51 and rotates following the photoreceptor drum 51 . The charging roller 52 is applied with a charging voltage from a charging voltage power source 111 (FIG. 10) to uniformly charge the surface of the photosensitive drum 51 .

The developing roller 54 is arranged so as to be in contact with the surface of the photoreceptor drum 51, and rotates in a direction opposite to that of the photoreceptor drum 51 (a direction in which the movement direction of the surface at the contact portion is the forward direction). The developing roller 54 is applied with a developing voltage from a developing voltage power source 112 (FIG. 10), and develops the electrostatic latent image on the surface of the photosensitive drum 51 with toner (developer).

The supply roller 55 is arranged so as to be in contact with the surface of the developing roller 54 and rotates in the same direction as the developing roller 54 (in the direction opposite to the moving direction of the surface at the contact portion). The supply roller 55 receives a supply voltage from a supply voltage power source 113 (FIG. 10) and supplies toner to the developing roller 54 .

The toner cartridge 56 is a detachable container containing toner as a developer. The toner is, for example, black toner, but is not limited to this. The toner cartridge 56 supplies toner to the developing roller 54 and the supply roller 55 .

The image forming unit 5 is also called an image drum unit (ID unit) or a process unit.

A transfer roller 57 as a transfer unit is arranged so as to contact the surface of the photosensitive drum 51 . A transfer voltage is applied to the transfer roller 57 from a transfer voltage power supply 114 (FIG. 10). Due to this transfer voltage, the toner image on the surface of the photosensitive drum 51 is transferred onto the medium P passing between the photosensitive drum 51 and the transfer roller 57 .

The image forming apparatus 2 is configured to form a monochrome image by the image forming unit 5, but is not limited to such a configuration. For example, a plurality of image forming units for yellow, magenta, cyan, black, etc. may be arranged in the conveying direction of the medium P to form a color image.

The fixing device 1 has a fixing roller 11 and a pressure roller 12 . The fixing roller 11 incorporates heaters 13 and 14 such as halogen lamps. The pressure roller 12 is pressed against the fixing roller 11 to form a nip portion N. As shown in FIG. The fixing roller 11 and pressure roller 12 apply heat and pressure to the medium P passing through the nip portion N to fix the toner image onto the medium P. As shown in FIG. A configuration of the fixing device 1 will be described later.

A jam detection sensor S1 is arranged downstream of the fixing device 1 in the direction in which the medium P is conveyed. The jam detection sensor S<b>1 is used to detect a jam of the medium P in the fixing device 1 .

The medium ejection section 7 has an ejection roller 71 that feeds the medium P that has passed through the fixing device 1 into an ejection transportation path 70 and an ejection roller 72 that ejects the medium P that has been transported along the ejection transportation path 70 . A stacker 73 on which the ejected medium P is placed is formed on the top cover 2B.

The image forming apparatus 2 also includes a reversing conveying section 8 that reverses the medium P having the toner image fixed on its surface and conveys it to the registration rollers 65 via the return conveying path 86 for double-sided printing. Further, a guide 75 is provided for selectively guiding the medium P that has passed through the fixing device 1 to the ejection conveying path 70 or the evacuation path 80 .

The reversing conveying section 8 has two pairs of conveying rollers 81 and 82 along the evacuation path 80 and three pairs of conveying rollers 83 , 84 and 85 along the return conveying path 86 . The conveying rollers 81 , 82 rotate in both forward and reverse directions, pull the medium P into the evacuation path 80 , reverse the front and back, and send it out to the return conveying path 86 .

The transport rollers 83 , 84 , 85 transport the medium P along the return transport path 86 . The return transport path 86 merges with the transport path 64 upstream of the registration rollers 65 . If the image forming apparatus 2 does not have a double-sided printing function, the reversing/conveying section 8 may not be provided.

In FIG. 1, the axial direction of the photosensitive drum 51 is defined as the X direction. The X direction is the axial direction of each roller in the image forming apparatus 2, and is also the width direction of the medium P to be conveyed. The moving direction of the medium P when the medium P passes through the image forming unit 5 is defined as the Y direction. A direction perpendicular to the X direction and the Y direction is defined as the Z direction. Here, the Z direction is the vertical direction.

Regarding the Y direction, the +Y direction is the transport direction when the medium P passes through the image forming unit 5, and the -Y direction is the opposite direction. Regarding the X direction, the +Y direction is the right-hand direction, and the left-hand direction is the -X direction. As for the Z direction, the upward direction in FIG. 1 is the +Z direction, and the downward direction is the −Z direction. Note that these directions do not limit the orientation of the image forming apparatus 2 .

<Structure of Fixing Device 1>
Next, the configuration of the fixing device 1 will be described. FIG. 2 is a cross-sectional view showing the configuration of the fixing device 1. As shown in FIG. 3 is a perspective view of the fixing device 1 viewed from the -Y direction, and FIG. 4 is a perspective view of the fixing device 1 viewed from the +Y direction.

As shown in FIG. 2, the fixing device 1 has a fixing roller 11 as a fixing member, a pressure roller 12 as a pressure member, and a housing 20 that houses them. Both the fixing roller 11 and the pressure roller 12 have their longitudinal directions set in the X direction.

As shown in FIGS. 3 and 4, the housing 20 includes a front cover 20a on the front (−Y direction), a rear cover 20b on the rear (+Y direction), and side covers on both left and right sides (−X direction and +X direction). 20c and 20d, a lower (-Z direction) lower cover 20e, and an upper (+Z direction) top cover 20f.

Components of the fixing device 1 such as the fixing roller 11 and the pressure roller 12 are arranged in a space surrounded by these covers 20a to 20f. An inlet 18 is formed in the front cover 20a, and an outlet 19 is formed in the rear cover 20b.

As shown in FIG. 2, a nip portion N (also referred to as a fixing nip) is formed between the fixing roller 11 and the pressure roller 12, and the medium P introduced into the housing 20 from the introduction port 18 passes through the nip portion. Pass N. The toner image on the medium P adheres to the medium P with a weak electrostatic force, but is melted by the heat of the fixing roller 11 and fixed on the medium P by the pressure of the pressure roller 12 .

The fixing roller 11 has a substantially cylindrical substrate 11a, an elastic layer 11b covering the surface of the substrate 11a, and a surface layer 11c covering the surface of the elastic layer 11b. The base material 11a is made of metal such as aluminum or stainless steel. The elastic layer 11b is made of resin such as silicone rubber. The surface layer 11c is made of fluororesin such as PTFE (polytetrafluoroethylene) or PFA (perfluoroalkoxyalkane).

Shafts are formed at both ends of the fixing roller 11 in the X direction. Both shaft portions of the fixing roller 11 are rotatably supported by bearings attached to side covers 20c and 20d (FIGS. 3 and 4) of the housing 20. As shown in FIG.

The fixing roller 11 has a hollow structure inside which heaters 13 and 14 are arranged. The heaters 13 and 14 are long in the X direction and arranged side by side in the Y direction. The heaters 13 and 14 are halogen heaters, for example.

However, the heaters 13 and 14 are not limited to halogen heaters, and may be other types of heaters such as planar heaters. Also, although the two heaters 13 and 14 are arranged side by side in the Y direction here, the number of heaters in the fixing roller 11 may be one.

The pressure roller 12 has a substantially cylindrical substrate 12a and an elastic layer 12b formed on the surface of the substrate 12a. The base material 12a is made of metal such as aluminum or stainless steel. The elastic layer 12b is made of resin such as foamed silicone rubber or silicone rubber. The surface of the elastic layer 12b may be covered with a surface layer made of PFA, PTFE, or the like.

Axial portions are formed at both ends of the pressure roller 12 in the X direction. Both shaft portions of the pressure roller 12 are attached to the swing frame 45 respectively. The swing frame 45 is swingably supported around a support shaft 46 provided inside the side covers 20c and 20d (FIGS. 3 and 4) of the housing 20, and the pressure roller 12 is supported by a spring member (not shown). It is urged in the direction of pressing against the fixing roller 11 .

A temperature sensor 28 is provided so as to be in contact with the surface of the fixing roller 11 . The temperature sensor 28 detects the temperature of the surface of the fixing roller 11 and outputs it to the fixing control section 118 (FIG. 10) described later. The temperature sensor 28 is a contact-type thermistor here, but may be a non-contact-type sensor such as a thermopile.

A front guide 21 is arranged upstream of the fixing roller 11 and the pressure roller 12 in the direction in which the medium P is transported (hereinafter referred to as the “medium transport direction”), that is, in the −Y direction. A medium P sent from the image forming unit 5 is introduced into the housing 20 through the introduction port 18 of the front cover 20 a and guided to the nip portion N by the front guide 21 .

The front guide 21 has a plurality of ribs 21a extending in the Y direction, as shown in FIG. The ribs 21a are arranged at intervals in the X direction. The rib 21 a guides the medium P to the nip portion N by contacting the medium P. As shown in FIG.

The front guide 21, as shown in FIG. 2, has an inclination such that the height increases in the +Y direction. However, the front guide 21 does not necessarily have to have such an inclination.

A separation claw 15 is provided on the downstream side of the fixing roller 11 in the medium conveying direction (that is, in the +Y direction) so as to contact the surface of the fixing roller 11 . The separation claw 15 separates the medium P adhering to the surface of the fixing roller 11 from the surface of the fixing roller 11 .

A guide roller 16 and a guide surface 17 are provided on the downstream side of the separation claw 15 in the medium conveying direction. The guide roller 16 guides the medium P separated from the fixing roller 11 by the separation claw 15 to the guide surface 17 . The guide surface 17 guides the medium P that has passed through the nip portion N from above (+Z direction).

Further, a rear guide 22 as a guide member is arranged downstream of the fixing roller 11 and the pressure roller 12 in the medium conveying direction. The rear guide 22 guides the medium P that has passed through the nip portion N from below (-Z direction).

The rear guide 22 is made of heat-resistant resin. More specifically, it is made of a composite material in which PET (polybutylene terephthalate) is reinforced with glass fibers. It is desirable that the front guide 21 is also made of the same material. The rear guide 22 is configured to be rotatable about the rotation axis Ax in the X direction so that the discharge port 19 can be opened when a jam of the medium P occurs.

FIG. 5 is a perspective view showing the rear guide 22. FIG. Here, each direction will be described assuming that the rear guide 22 is at a position for guiding the medium P (a guide position to be described later: FIG. 2). The rear guide 22 has an upper surface portion 22a substantially parallel to the XY plane and a panel portion 22b substantially parallel to the XZ plane.

The upper surface portion 22a and the panel portion 22b of the rear guide 22 are both plate-shaped elongated in the X direction. The panel portion 22b extends downward (−Z direction) from the rear end (+Y direction end) of the upper surface portion 22a. Support shafts 22c serving as the center of rotation of the rear guide 22 are provided at the lower ends (ends in the -Z direction) of both ends in the X direction of the panel portion 22b. A rotation axis Ax of the rear guide 22 is defined by the support shaft 22c.

A plurality of rib pairs consisting of ribs 23 and 24 are arranged in the X direction on the upper surface portion 22a of the rear guide 22 . Both ribs 23 and 24 extend in the Y direction and have a thickness in the X direction. Also, the ribs 23 and 24 are arranged side by side in the Y direction. More specifically, the rib 23 is positioned upstream (-Y direction) in the medium transport direction, and the rib 24 is positioned downstream (+Y direction) in the medium transport direction. The ribs 23, 24 are also called locking portions.

At the -X direction end of the panel portion 22b of the rear guide 22, a gripping portion 26 is formed to be gripped by the user when the rear guide 22 is rotated. The grip portion 26 protrudes from the housing 20 in the -X direction so that the user can easily grip it (see FIG. 4).

FIG. 6 is a diagram showing the rear guide 22 and its surroundings when it is in a position for guiding the medium P (referred to as a guide position). The ribs 23 and 24 of the rear guide 22 are arranged at positions through which the medium P passes through the nip portion N between the fixing roller 11 and the pressure roller 12 .

The rib 23 has a tip portion 23d facing the nip portion N substantially in the Y direction. The rib 23 also has an inclined portion 23b as a facing portion extending in the +Y direction from the tip portion 23d. The inclined portion 23b is inclined so that its height (Z-direction position) increases as it progresses in the +Y direction. The rib 23 also has a falling portion 23a extending in the -Z direction from the terminal end (the end in the +Y direction) of the inclined portion 23b. A top portion 23c as a contact portion is formed between the inclined portion 23b and the falling portion 23a.

The rib 24 has an inclined portion 24b as a facing portion extending from the lower end of the falling portion 23a of the rib 23 in the +Y direction. The inclined portion 24b is inclined so that its height (Z-direction position) increases as it progresses in the +Y direction. The rib 24 also has a falling portion 24a extending in the -Z direction from the terminal end (the end in the +Y direction) of the inclined portion 24b. A top portion 24c as a contact portion is formed between the inclined portion 24b and the falling portion 24a.

With this configuration, the medium P that has passed through the nip portion N contacts the top portions 23c and 24c of the ribs 23 and 24 and is transported in the +Y direction while facing the inclined portions 23b and 24b of the ribs 23 and 24. be done. That is, the tops 23c and 24c of the ribs 23 and 24 form a transport path (transport reference plane) for the medium P. As shown in FIG.

A claw-like convex portion A is formed by the falling portion 23a, the inclined portion 23b, and the top portion 23c of the rib 23. As shown in FIG. A concave portion B is formed between the falling portion 23 a of the rib 23 and the inclined portion 24 b of the rib 24 . As a result, as will be described later, the jammed medium P can be removed from the fixing device 1 by hooking it on the protrusions A of the ribs 23 .

Although the falling portion 24a of the rib 24 is flush with the panel portion 22b of the rear guide 22 here, it may be located away from the panel portion 22b of the rear guide 22 in the -Y direction. However, it is desirable that the ribs 24 do not protrude outward from the housing 20 when the rear guide 22 is at the guide position.

Further, the rear guide 22 shown in FIG. 5 has a shape in which the center of the panel portion 22b in the X direction is retracted in the -Y direction, but such a retraction portion may not necessarily be provided.

FIG. 7 is a cross-sectional view showing a state in which the rear guide 22 is rotated about the rotation axis Ax. The position of the rear guide 22 shown in FIG. 7 is called a retracted position (open position). When a media P jam occurs, the user rotates the rear guide 22 in the direction indicated by the arrow R by gripping the grip portion 26 (FIG. 5) and pulling it in the +Y direction.

When the rear guide 22 is at the retracted position, most of the rear guide 22 including the ribs 23 and 24 projects in the +Y direction of the housing 20, and the discharge port 19 of the housing 20 is opened. The rear guide 22 is urged to rotate toward the guide position shown in FIGS. 2 and 6 by a torsion spring 29 as an urging member.

FIG. 8 shows the initial state of rotation of the rear guide 22 from the guide position (FIG. 2) to the retracted position (FIG. 7). In FIG. 8, reference symbol L1 indicates a conveyance reference plane defined by tops 23c and 24c of ribs 23 and 24 when rear guide 22 is at the guide position (FIG. 2). Reference L2 denotes a guide surface defined by the guide surface 17. FIG. A transport area for the medium P is defined between the transport reference surface L1 and the guide surface L2.

In the course of the rear guide 22 rotating from the guide position (FIG. 2) toward the retracted position (FIG. 7), the rib 23 (in particular, the top portion 23c) crosses the conveyance reference plane L1 to reach the guide plane, as shown in FIG. Get closer to 17. In other words, part of the convex portion A of the rib 23 rides over the transport reference plane L1 toward the guide surface 17 . As a result, when removing a jammed medium P, as will be described later, the medium P can be removed by holding it between the rib 23 and the guide surface 17 .

FIG. 9 is a sectional view showing a state in which the nip portion N between the fixing roller 11 and the pressure roller 12 is opened. As described above, the pressure roller 12 is held by the swing frame 45 that swings around the support shafts 46 provided on the side covers 20c and 20d (FIGS. 3 and 4) of the housing 20. As shown in FIG.

A release cam 41 for swinging the swing frame 45 is provided inside the housing 20 . The release cam 41 is an eccentric cam whose distance from the center of rotation to the outer circumference varies depending on the rotational position (angle), and is rotationally driven by the cam motor 123 (FIG. 10). A contact lever 44 connected to a swing frame 45 is arranged at a position where it can contact the release cam 41 . This contact lever 44 is omitted in FIGS.

When the release cam 41 rotates and biases the contact lever 44 , the swing frame 45 swings in such a manner that the pressure roller 12 separates from the fixing roller 11 . When the release cam 41 rotates further and the contact with the contact lever 44 is released, the swing frame 45 swings in the direction in which the pressure roller 12 is pressed against the fixing roller 11 . As a result, the nip portion N between the fixing roller 11 and the pressure roller 12 is opened and closed.

Although the nip portion N between the fixing roller 11 and the pressure roller 12 is opened and closed by the release cam 41 here, the release cam 41 is not provided, and the fixing roller 11 and the pressure roller 12 are always pressed against each other. It is also possible to keep it.

<Control System of Image Forming Apparatus>
Next, a control system of the image forming apparatus 2 will be described. FIG. 10 is a block diagram showing the control system of the image forming apparatus 2. As shown in FIG. The image forming apparatus 2 includes a print control unit 101, an I/F (interface) control unit 102, a reception memory 103, an image data editing memory 104, an operation unit 105, a sensor group 106, and a power supply control unit 110. , a head control unit 115 , a drive control unit 116 , a fixing drive control unit 117 , a fixing control unit 118 , a cam control unit 119 , and a paper feed/conveyance control unit 120 . These control units and memories can be mounted on the same control board, except for the power supply control unit 110. FIG.

The print control unit 101 includes a microprocessor, a ROM (Read Only Memory), a RAM (Random Access Memory), an input/output port, a timer, and the like. The print control unit 101 receives print data and control commands from a host device via the I/F control unit 102 and controls the printing operation of the image forming apparatus 2 .

A reception memory 103 temporarily stores print data input from a host device via the I/F control unit 102 . The image data editing memory 104 receives the print data stored in the reception memory 103 and records image data formed by editing the print data, that is, image data.

The operation unit 105 is an operation panel including a display unit (for example, LED) for displaying the state of the image forming apparatus 2 and an operation unit (for example, switch) for the operator to input instructions. The sensor group 106 includes various sensors for monitoring the operating state of the image forming apparatus 2, such as the jam detection sensor S1, the temperature/humidity sensor, and the density sensor.

The power control unit 110 includes a charging voltage power supply 111 that applies a charging voltage to the charging roller 52 , a development voltage power supply 112 that applies a development voltage to the developing roller 54 , and a supply voltage power supply 113 that applies a supply voltage to the supply roller 55 . , and a transfer voltage power source 114 that applies a transfer voltage to the transfer roller 57 .

The head controller 115 controls light emission of the exposure head 53 based on the image data. The drive control unit 116 performs control to drive the drive motor 121 that rotates the photosensitive drum 51 of the image forming unit 5 .

A fixing drive control unit 117 controls driving of a fixing motor 122 that rotates the fixing roller 11 . Note that the discharge rollers 71 and 72 are rotated by rotation transmission from the fixing motor 122 . A fixing control unit 118 has a temperature control circuit and controls the heaters 13 and 14 based on the output signal of the temperature sensor 28 .

The cam control unit 119 controls driving the cam motor 123 that rotates the release cam 41 . The sheet feeding/conveying control unit 120 controls the driving of the sheet feeding motor 124 that rotates the pickup roller 61 and the feed roller 62 and the conveying motor 125 that rotates the registration roller 65 and the conveying roller 66 .

<Printing operation of image forming apparatus>
Next, a printing operation (image forming operation) of the image forming apparatus 2 will be described with reference to FIGS. 1 and 10. FIG. When the print control unit 101 of the image forming apparatus 2 receives a print command and print data from the host device via the I/F control unit 102, the print operation is started. The print control unit 101 temporarily records the print data in the reception memory 103 , edits the recorded print data to generate image data, and records the image data in the image data edit memory 104 .

In the medium supply unit 6, the pickup roller 61 is rotated by the paper feed motor 124, and the feed roller 62 is rotated to feed the medium P in the medium cassette 60 one by one to the transport path. Further, the registration rollers 65 and the transport rollers 66 are rotated by the transport motor 125 to correct the skew of the medium P and transport it to the image forming unit 5 .

In the image forming unit 5, charging voltage, developing voltage and supply voltage are applied to the charging roller 52, the developing roller 54 and the supply roller 55 from the charging voltage power supply 111, the developing voltage power supply 112 and the supply voltage power supply 113, respectively.

Further, the photosensitive drum 51 is rotated by the drive motor 121 . As the photosensitive drum 51 rotates, the charging roller 52, the developing roller 54, and the supply roller 55 also rotate. The charging roller 52 uniformly charges the surface of the photosensitive drum 51 with its charging voltage.

The print control unit 101 also transmits the image data recorded in the image data editing memory 104 to the head control unit 115, and the head control unit 115 drives the exposure head 53 to expose the surface of the photosensitive drum 51. , forming an electrostatic latent image.

The electrostatic latent image formed on the surface of photoreceptor drum 51 is developed with toner adhering to developing roller 54 to form a toner image on the surface of photoreceptor drum 51 . When the toner image approaches the transfer roller 57 due to the rotation of the photosensitive drum 51 , a transfer voltage is applied to the transfer roller 57 from the transfer voltage power source 114 . As a result, the toner image formed on the photosensitive drum 51 is transferred onto the medium P. As shown in FIG.

The medium P onto which the toner image has been transferred in this way is further conveyed by the rotation of the photosensitive drum 51 and reaches the fixing device 1 .

In the fixing device 1 , the cam control section 119 drives the cam motor 123 at the start of the printing operation, thereby operating the release cam 41 to press the pressure roller 12 against the fixing roller 11 to form the nip portion N. Further, the fixing drive control section 117 drives the fixing motor 122, thereby rotating the pressure roller 12. FIG. Further, the heaters 13 and 14 are heated to a predetermined fixing temperature by the fixing control section 118 .

The medium P conveyed from the image forming unit 5 to the fixing device 1 is guided by the front guide 21 to the nip portion N between the fixing roller 11 and the pressure roller 12, and is subjected to heat and pressure at the nip portion N to be toner. The image is fixed on the medium P. The medium P on which the toner image has been fixed is conveyed by the discharge rollers 71 and 72 of the medium discharge section 7 and discharged to the outside of the image forming apparatus 2 . The ejected media P are stacked on the stacker 73 . Thus, the printing operation on the medium P is completed.

In the case of double-sided printing, the medium P having the toner image fixed on the surface thereof by the fixing device 1 is introduced into the evacuation path 80 by the switching guide 75 . After that, the transport rollers 81 and 82 are rotated forward by the transport motor 125 to draw the medium P into the evacuation path 80 , and the transport rollers 81 and 82 are reversed to send the medium P out of the evacuation path 80 .

Further, the transport rollers 83 , 84 , 85 are rotated by the transport motor 125 to transport the medium P along the return transport path 86 . The medium P conveyed along the return conveying path 86 reaches the conveying path 64 before the registration roller 65, and then a toner image is formed on the back surface of the medium P. FIG.

<Action>
Next, the operation of this embodiment will be described. FIG. 11 shows a state in which a jam of the medium P occurs inside the fixing device 1 and the medium P remains in a bellows shape. The rear guide 22 is in the guide position. In the above printing operation, the print control unit 101 determines that a jam of the medium P has occurred and starts the printing operation when the detection signal of the jam detection sensor S1 is not received after a predetermined time has passed since the start of transportation of the medium P. Stop. Also, a message notifying the occurrence of a jam is displayed on the display section of the operation section 105 .

When the user finds the occurrence of the jam through the operation unit 105 , the user removes the fixing device 1 from the image forming apparatus 2 and removes the medium P from the fixing device 1 .

When the adhesive force between the medium P and the fixing roller 11 is strong, the medium P is not smoothly separated from the fixing roller 11 by the separation claw 15, and as a result, the downstream side of the nip portion N in the medium conveying direction (+Y direction). In some cases, the medium P remains in a bellows shape.

If the leading end of the medium P protrudes from the fixing device 1 , the user can remove the medium P from the fixing device 1 by grasping the leading end of the medium P with fingers. However, when the jammed medium P is accumulated inside the fixing device 1 as shown in FIG. 11, it is difficult for the user to grasp and remove the medium P. As shown in FIG.

In the fixing device 1 of the first embodiment, the jammed accordion-shaped media P accumulate along the inclined portions 23 b and 24 b of the ribs 23 and 24 of the rear guide 22 . At this time, part of the medium P is caught by the protrusion A on the claw of the rib 23 , in other words, part of the medium P is fitted in the recess B of the rib 23 .

FIG. 12 is a diagram showing a state in which the rear guide 22 is rotated from the guide position to the retracted position. The rotation of the rear guide 22 is performed by the user holding the grip portion 26 of the rear guide 22 and rotating it, as described above.

The rotation of the rear guide 22 causes the rib 23 of the rear guide 22 to move substantially in the +Y direction, and the medium P is pulled out of the fixing device 1 while being hooked on the claw-shaped protrusion A. In other words, the medium P is pushed out in the +Y direction by the falling portions 23a of the ribs 23. As shown in FIG. In other words, the medium P is pulled out of the fixing device 1 while a part of the medium P is fitted in the concave portion B of the rib 23 .

Therefore, the user can remove the jammed medium P from the fixing device 1 simply by rotating the rear guide 22 from the guide position toward the retracted position.

Generally, when the medium P jams in the fixing device 1, most of the medium P is conveyed from the nip portion N in the +Y direction by the rotation of the fixing roller 11 until the printing operation is stopped. Even if the rear end portion of the medium P is sandwiched by the nip portion N, the medium P can be pulled out from the nip portion N by rotating the rear guide 22 to pull out the medium P.

Further, if the release cam 41 (FIG. 9) is driven to open the nip portion N at the end of the printing operation after jam detection, the medium P can be pulled out with less force.

As described with reference to FIG. 8, when the rear guide 22 is at the guide position and the plane defined by the tops 23c and 24c of the ribs 23 and 24 is defined as the transfer reference plane P1, the rear guide 22 is positioned at the guide position. When rotating toward the retracted position, the top portion 23c of the rib 23 once moves toward the guide surface 17. As shown in FIG.

Therefore, when the rear guide 22 rotates, the medium P can be held between the rib 23 and the guide surface 17 and pulled out. As a result, the medium P can be easily caught by the projections A of the ribs 23, and the medium P can be pulled out more effectively.

FIG. 13A is a schematic diagram showing the ribs 23 and 24 when the rear guide 22 is at the guide position. FIG. 13B is a schematic diagram showing the ribs 23 and 24 at the beginning of the rotation of the rear guide 22 from the guide position to the retracted position.

As shown in FIG. 13A, when the rear guide 22 is at the guide position, the trailing portion 23a of the rib 23 is substantially perpendicular to the conveying reference plane L1 defined by the top portions 23c and 24c of the ribs 23 and 24. is making

On the other hand, as shown in FIG. 13B, in the initial state of rotation of the rear guide 22, the angle α of the trailing portion 23a of the rib 23 with respect to the transfer reference plane L1 is an obtuse angle. Therefore, the bellows-shaped medium P is easily caught on the protrusions A of the ribs 23 .

Here, the rear guide 22 has a convex portion A including a falling portion 23a, an inclined portion 23b and a top portion 23c of the rib 23, and a concave portion B between the falling portion 23a of the rib 23 and the inclined portion 23b of the rib 24. have. However, the rear guide 22 may have only one of the convex portion and the concave portion. In other words, the rear guide 22 may have at least one of the convex portion and the concave portion.

Although the rear guide 22 is rotatably supported around the rotation axis Ax here, the configuration is not limited to this. For example, the rear guide 22 may move straight between the guide position and the retracted position.

<Effect of Embodiment>
As described above, the fixing device 1 according to the first embodiment includes the fixing roller 11 as a fixing member used for heating the medium P, and the fixing roller 11 which is pressed against the fixing roller 11 (conveyance). a pressure roller 12 as a pressure member forming a nip portion N through which the medium P passes through; and a guide position provided downstream of the nip portion N in the medium transport direction to guide the transported medium P , and a rear guide 22 as a guide member movable between a retracted position (open position) retracted from the guide position. The rear guide 22 includes ribs 23 and 24 as locking portions having at least one of a convex portion A and a concave portion B in the medium P transport direction. As the rear guide 22 moves from the guide position to the retracted position, the ribs 23 and 24 of the rear guide 22 move downstream in the transport direction (+Y direction).

Because of this configuration, when the rear guide 22 is moved from the guide position to the retracted position, the jammed medium P is caught in the protrusion A (or partly fitted in the recess B). It is pulled out from the fixing device 1 . Therefore, by moving the rear guide 22 , the jammed medium P can be easily removed from the fixing device 1 .

Further, the rear guide 22 has a falling portion 23a (first surface) extending in a direction in which the distance from the transportation reference plane L1 increases, on the downstream side of the convex portion A in the medium transportation direction. Therefore, when the rear guide 22 is moved toward the retracted position, the falling portion 23a contacts the medium P and pushes it out. As a result, the medium P can be reliably pulled out.

Further, the rib 23 of the rear guide 22 intersects the conveyance reference plane L1 of the medium P while the rear guide 22 moves from the guide position to the retracted position. Therefore, by moving the rear guide 22 , the medium P can be held and pulled out between the rib 23 and the guide surface 17 .

Further, in the process of moving the rear guide 22 from the guide position to the retracted position, the angle α of the falling portion 23a with respect to the transport reference plane L1 becomes an obtuse angle. The medium P can be pulled out more reliably.

Further, a guide surface 17 (opposing surface) is provided so as to face the rear guide 22 and defines the transport area of the medium P between itself and the rear guide 22 . It has a top portion 23c (contact portion) that contacts and guides the medium P in the guide position. The top portion 23 c approaches the guide surface 17 while the rear guide 22 moves from the guide position to the retracted position. Therefore, the medium P can be pulled out while holding it between the rib 23 and the guide surface 17 .

Further, since the rear guide 22 is rotatable around the support shaft 22c orthogonal to the medium conveying direction, the structure for removing the jammed medium P becomes simpler and the space occupied can be reduced. can be done.

Second embodiment.
Next, a second embodiment will be described. FIG. 14 is a schematic diagram showing a fixing device 1A according to the second embodiment. The fixing device 1A of the second embodiment includes a holding member 31 that holds the medium P between itself and the rear guide 22A when the medium P is removed. In FIG. 14 , illustration of components other than the rear guide 22A, the holding member 31, the fixing roller 11, the pressure roller 12 and the housing 20 of the fixing device 1A is omitted.

The rear guide 22A has a rib 25 as a locking portion instead of the ribs 23, 24 (Fig. 2). The rib 25 has an inclined portion 25b extending in the +Y direction from the tip of the rear guide 22 on the nip portion N side. The inclined portion 25b is inclined so that its height (Z-direction position) increases as it progresses in the +Y direction. The rib 25 also has a falling portion 25a extending in the -Z direction from the terminal end (the end in the +Y direction) of the inclined portion 25b.

15 is a perspective view showing the rear guide 22A and the holding member 31. FIG. The holding member 31 is an elongated member that is long in the X direction, and is arranged to face the +Z side of the rear guide 22A. Here, each direction will be described assuming that the rear guide 22A is at the guide position.

The holding member 31 has a facing surface 31a on the side facing the rear guide 22A. The facing surface 31 a has a shape along the inclined portion 25 b of the rib 25 . Protrusions 31c as engaging portions (guided portions) are formed on both end faces 31b of the clamping member 31 in the X direction.

Guide rails 32 elongated in the Z direction are integrally formed at both ends of the rear guide 22A in the X direction. The guide rail 32 is arranged at a position sandwiching the holding member 31 in the X direction. A guide groove 32a extending in the Z direction is formed on the surface of the guide rail 32 on the holding member 31 side. The protrusion 31c of the holding member 31 is slidably engaged with the guide groove 32a. The holding member 31 is supported by a guide rail 32 so as to be movable in the Z direction.

A gripping portion 33 projecting in the +Y direction is formed in the central portion of the gripping member 31 in the X direction. The grip part 33 is formed in a flat plate shape parallel to the XY plane, for example. The grip portion 33 is a portion that a user grips when moving the holding member 31 . By gripping the grip portion 33 and moving the holding member 31 in the Z direction, the projection 31c slides in the guide groove 32a, and the holding member 31 moves along the guide rail 32 in the Z direction.

The rear guide 22A may be provided with a gripping portion 27 at the center in the X direction instead of the gripping portion 26 (FIG. 5) of the first embodiment. The grip part 27 is formed in a flat plate shape parallel to the XY plane, for example. By arranging the gripping portion 33 to overlap the gripping portion 27 of the rear guide 22A when the gripping member 31 is at the lower end of the movement range, the user can grip the gripping portion 33 and the gripping portion 27 together.

FIG. 16 is a schematic diagram showing an example of a configuration for holding the holding member 31 at a position separated from the rear guide 22A in the +Z direction. In the guide groove 32a of the guide rail 32, a depression 32c that engages with the protrusion 31c of the holding member 31 is formed at a predetermined position in the Z direction. The holding member 31 is held with the projection 31c engaged with the recess 32c.

In FIG. 16, for convenience of illustration, the depth of the recess 32c in the guide groove 32a is shown to be deep. Any depth that allows engagement (and disengagement) with the . In FIG. 15 described above, the recess 32c is omitted.

When the protrusion 31c is engaged with the recess 32c, the clamping member 31 is separated from the rear guide 22A by a predetermined distance in the +Z direction. A transport area for the medium P is formed between the holding member 31 and the rear guide 22A. The position of the holding member 31 at this time is called the separated position. When the holding member 31 is at the separated position, the facing surface 31a of the holding member 31 has the same function as the guide surface 17 (FIG. 2) described in the first embodiment.

17A and 17B are schematic diagrams showing a method of removing the medium P in the fixing device 1A. As shown in FIG. 14 described above, when a jam of the medium P occurs in the fixing device 1A, the user grips the grip portion 33 and moves the nipping member 31 in the -Z direction (that is, toward the rear guide 22A). reduce.

As a result, as shown in FIG. 17A, the holding member 31 moves along the guide rail 32 in the -Z direction, and the medium P is held between the rib 25 of the rear guide 22A and the holding member 31. . The position of the holding member 31 at this time is also called a holding position.

When the user pulls the grip part 33 in the +Y direction, the rear guide 22A and the holding member 31 rotate in the direction indicated by the arrow R around the rotation axis Ax as shown in FIG. 17(B). That is, the rear guide 22A rotates together with the holding member 31 toward the retracted position (open position).

At this time, the medium P sandwiched between the sandwiching member 31 and the rib 25 of the rear guide 22A is pulled out from the fixing device 1 . That is, the user can remove the medium P from the fixing device 1A by gripping the grip portion 33, pulling down the gripping member 31 in the -Z direction, and then pulling it in the +Y direction.

After removing the medium P from the fixing device 1A, the user grips the grip portion 33, rotates the rear guide 22A together with the holding member 31 to the guide position, and further raises the holding member 31 in the +Z direction. When the protrusion 31c of the holding member 31 engages with the recess 32c (FIG. 16) of the guide rail 32, the holding member 31 is held at a position separated from the rear guide 22A in the +Z direction.

A fixing device 1A of the second embodiment is configured in the same manner as the fixing device 1 of the first embodiment except for the points described above. The ribs 23 and 24 described in the first embodiment may be provided instead of the rib 25 of the rear guide 22A.

As described above, the fixing device 1A of the second embodiment includes the holding member 31 that holds the medium P between itself and the rear guide 22A. can be moved to the retracted position while holding the . Therefore, the jammed medium P can be easily removed from the fixing device 1A.

Third embodiment.
Next, a third embodiment will be described. 18 and 19 are schematic diagrams showing a fixing device 1B according to the third embodiment. The fixing device 1B of the third embodiment includes a transmission mechanism 34 as a first transmission mechanism for transmitting the rotation of the rear guide 22A to the fixing roller 11. As shown in FIG.

The fixing device 1B has the rear guide 22A described in the second embodiment. A release cam 41 (FIG. 9) for separating and contacting the fixing roller 11 and the pressure roller 12 is not provided. In FIG. 18, illustration of components other than the rear guide 22A, the transmission mechanism 34, the fixing roller 11, the pressure roller 12 and the housing 20 is omitted.

The transmission mechanism 34 has a rear guide gear 22g, a transmission gear 35, an intermediate gear 36, and a fixing roller gear 11g. These gears are arranged outside in the -X direction with respect to the transport area of the medium P, and are indicated by dashed lines in FIGS.

The rear guide gear 22g is fixed to the rear guide 22A and is rotatable around the rotation axis Ax. The transmission gear 35 meshes with the rear guide gear 22g and is supported so as to revolve around the rotation axis Ax around the rear guide gear 22g.

The intermediate gear 36 meshes with the transmission gear 35 when the transmission gear 35 reaches a predetermined revolution position (FIG. 19). The fixing roller gear 11g is fixed to one end of the fixing roller 11 in the X direction and meshes with the intermediate gear 36. As shown in FIG.

The position of the transmission gear 35 shown in FIG. 18 is called the first position. The position of the transmission gear 35 shown in FIG. 19 is called the second position.

FIG. 20 is a schematic diagram showing a configuration example of the transmission mechanism 34. As shown in FIG. A lever 22e rotatable about the rotation axis Ax is attached to the rear guide gear 22g. A shaft portion 35a of a transmission gear 35 is supported by the lever 22e.

A torque limiter 22f is provided between the rear guide gear 22g and the lever 22e. The rear guide gear 22g and the lever 22e rotate together due to friction, but when a load above a certain level is applied between them, a slip occurs due to the action of the torque limiter 22f. It will not rotate.

A shaft portion 35a of the transmission gear 35 is supported by a lever 22e and guided by an arcuate guide groove 37 provided in the housing 20 (FIG. 18).

The guide groove 37 regulates the revolution range of the transmission gear 35 between a first position (indicated by a solid line) and a second position (indicated by a broken line). The first position is located on the upstream side in the rotation direction of the lever 22e indicated by the bold arrow in FIG. 20, and the second position is located on the downstream side in the rotation direction.

When the rear guide 22A is at the guide position, the transmission gear 35 is at the first position as shown in FIG. At this time, the transmission gear 35 is not in mesh with the intermediate gear 36 .

When the rear guide 22A is rotated from the guide position toward the retracted position in the direction indicated by the arrow R, the rear guide gear 22g fixed to the rear guide 22A rotates in the same direction as the arrow R as shown in FIG.

The rotation of the rear guide gear 22g causes the lever 22e to rotate in the same direction, and the transmission gear 35 to revolve around the rear guide gear 22g. When the shaft portion 35 a of the transmission gear 35 reaches the second position, the transmission gear 35 meshes with the intermediate gear 36 .

When the transmission gear 35 reaches the second position (FIG. 19), the shaft portion 35a contacts the end of the guide groove 37, and the torque limiter 22f acts to move the rear guide gear 22g and the lever 22e. Therefore, even if the rear guide gear 22g rotates, the lever 22e does not rotate.

In this state, the rotation of the rear guide gear 22g can be transmitted to the fixing roller gear 11g via the transmission gear 35 and the intermediate gear . At this point, the rear guide 22A has not yet reached the retracted position.

When the rear guide 22A further rotates toward the retracted position in the direction indicated by the arrow R, the rotation of the rear guide gear 22g is transmitted to the fixing roller gear 11g via the transmission gear 35 and the intermediate gear 36, and the fixing roller 11 moves toward the arrow C. Rotate in the direction indicated by . That is, rotation of the rear guide 22A is converted into rotation of the fixing roller 11. FIG.

21A and 21B are diagrams showing the operation of the fixing device 1B of the third embodiment. As shown in FIG. 21A, when a jam of the medium P occurs inside the fixing device 1B, the trailing edge portion of the medium P is between the fixing roller 11 and the pressure roller 12 when the printing operation is stopped. It may be sandwiched in the nip portion N between them.

At this time, as shown in FIG. 21(B), when the user rotates the rear guide 22A toward the retracted position in the direction indicated by the arrow R, the transmission mechanism 34 (FIG. 20) causes the fixing roller 11 to rotate. Rotate in the direction indicated by C. Therefore, even if the trailing edge portion of the medium P is sandwiched between the nips N, the rotation of the fixing roller 11 allows the entire medium P to be sent out to the downstream side of the nips N in the medium conveying direction.

The user can remove the medium P from the fixing device 1B by grasping the leading edge of the medium P protruding outside the fixing device 1B.

It should be noted that the fixing roller 11 does not need to be rotated greatly, and may be rotated by an angle necessary for the trailing edge portion of the medium P to escape from the nip portion N. FIG. The rotation angle of the fixing roller 11 can be appropriately set according to the number of teeth of each gear of the transmission mechanism 34 and the like.

A fixing device 1B according to the third embodiment is configured in the same manner as the fixing device 1A according to the second embodiment except for the points described above. The ribs 23 and 24 described in the first embodiment may be provided instead of the rib 25 of the rear guide 22A. Also, the holding member 31 described in the second embodiment may be provided.

As described above, the fixing device 1B of the third embodiment includes the transmission mechanism 34 that transmits the rotation of the rear guide 22A to the fixing roller 11, and rotates the rear guide 22A from the guide position to the retracted position. Then, the fixing roller 11 is rotated by the transmission mechanism 34 to feed the medium P downstream in the transport direction. Therefore, the user can completely remove the medium P from the nip portion N by rotating the rear guide 22A. That is, the medium P can be easily removed from the fixing device 1B.

Fourth embodiment.
Next, a fourth embodiment will be described. 22 and 23 are schematic diagrams showing a fixing device 1C according to the fourth embodiment. A fixing device 1C of the fourth embodiment includes the transmission mechanism 34 described in the third embodiment, and further includes the release cam 41 described in the first embodiment.

The release cam 41 is rotated by a cam motor 123 (FIG. 10). The release cam 41 and the cam motor 123 constitute a contact/separation mechanism for contacting or separating the fixing roller 11 and the pressure roller 12 .

At the start of the printing operation, the print control unit 101 (FIG. 10) drives the cam motor 123 by the cam control unit 119 to rotate the release cam 41 and press the pressure roller 12 against the fixing roller 11 as shown in FIG. Then, a nip portion N is formed. A printing operation is performed in this state.

When the jam detection sensor S1 (FIG. 1) detects a jam in the fixing device 1C, the print control unit 101 stops the printing operation, and the cam control unit 119 drives the cam motor 123 to rotate the release cam 41. Then, the pressure roller 12 is separated from the fixing roller 11 as indicated by an arrow D, and the nip portion N is opened.

In this state, the user rotates the rear guide 22A in the direction indicated by the arrow R as shown in FIG. As described in the third embodiment, when the rear guide 22A rotates from the guide position toward the retracted position as indicated by the arrow R, the transmission mechanism 34 causes the fixing roller 11 to rotate in the direction indicated by the arrow C. do.

Therefore, even if the trailing edge portion of the medium P remains in the nip portion N, the entire medium P can be sent out to the downstream side of the nip portion N by the rotation of the fixing roller 11 . The user can remove the medium P from the fixing device 1C by grasping the leading edge of the medium P that has protruded outside the fixing device 1B.

In the fourth embodiment, since the medium P is removed while the fixing roller 11 and the pressure roller 12 are separated from each other, the medium P can be pulled out with a lighter force. That is, the force required by the user to rotate the rear guide 22A is small.

A fixing device 1C according to the fourth embodiment is configured in the same manner as the fixing device 1B according to the third embodiment except for the points described above. The ribs 23 and 24 described in the first embodiment may be provided instead of the rib 25 of the rear guide 22A. Also, the holding member 31 described in the second embodiment may be provided.

As described above, the fixing device 1C of the fourth embodiment includes the transmission mechanism 34 for transmitting the rotation of the rear guide 22A to the fixing roller 11, and the fixing roller 11 and the pressure roller 12 are brought into contact or A release cam 41 is provided as a separation/contact mechanism for separating. By moving the rear guide 22A from the guide position to the retracted position while the fixing roller 11 and the pressure roller 12 are separated from each other, the fixing roller 11 rotates and feeds the medium P downstream in the medium conveying direction. Since the nip portion N is opened, the medium P can be pulled out with less force, and the force for rotating the rear guide 22A can be reduced.

Fifth embodiment.
Next, a fifth embodiment will be described. 24 and 25 are schematic diagrams showing a fixing device 1D according to the fifth embodiment. A fixing device 1D according to the fifth embodiment adds a transmission mechanism 40 as a second transmission mechanism for transmitting the rotation of the rear guide 22 to the release cam 41 to the fixing device 1 described in the first embodiment. It is a thing.

The fixing device 1D has the rear guide 22 described in the first embodiment. Components other than the rear guide 22, the transmission mechanism 40, the fixing roller 11, the pressure roller 12 and the housing 20 are omitted from FIGS.

The transmission mechanism 40 of the fixing device 1D has a rear guide gear 22g, a first intermediate gear 42, a second intermediate gear 43, and a release cam gear 41g. These gears are arranged outside in the -X direction with respect to the transport area of the medium P, and are indicated by dashed lines in FIGS.

The rear guide gear 22g is fixed to the rear guide 22 and is rotatable around the rotation axis Ax. The first intermediate gear 42 meshes with the rear guide gear 22g. The second intermediate gear 43 meshes with the first intermediate gear 42 . The release cam gear 41 g is fixed to the release cam 41 and meshes with the second intermediate gear 43 .

As shown in FIG. 25, when the rear guide 22 is rotated from the guide position toward the retracted position (open position) in the direction indicated by the arrow R, the rear guide gear 22g fixed to the rear guide 22 rotates in the same direction. .

The rotation of the rear guide gear 22g rotates the first intermediate gear 42 that meshes with the rear guide gear 22g, rotates the second intermediate gear 43 that meshes with the first intermediate gear 42, and rotates the release cam gear 41g that meshes with the second intermediate gear 43. Rotate. As a result, the release cam 41 rotates, and the pressure roller 12 is separated from the fixing roller 11 as indicated by an arrow D.

The method for removing the jammed medium P is as described in the first embodiment. That is, when the rear guide 22 is rotated toward the retracted position, the medium P is caught by the projections A of the ribs 23 of the rear guide 22 and pulled out from the fixing device 1D. At this time, the release cam 41 is rotated by the action of the transmission mechanism 40, the pressure roller 12 is separated from the fixing roller 11, and the nip portion N is opened. Therefore, even if the rear end portion of the medium P is sandwiched by the nip portion N, the medium P can be easily pulled out.

After removing the medium P, when the rear guide 22 is rotated toward the guide position, the release cam 41 is rotated by the action of the transmission mechanism 40, and the pressure roller 12 is pressed against the fixing roller 11 to form the nip portion N. be done.

Note that the cam motor 123 (FIG. 10) is not provided in the fifth embodiment, and the release cam 41 rotates only when interlocked with the rear guide 22 . However, the cam motor 123 may also be used in combination. In that case, a mechanism for switching rotation transmission may be provided so that the rotation of the release cam 41 at the start and end of the printing operation is not transmitted to the rear guide gear 22g. .

A fixing device 1D according to the fifth embodiment is configured in the same manner as the fixing device 1 according to the first embodiment except for the points described above. Instead of the ribs 22 and 23 of the rear guide 22, the rib 25 described in the second embodiment may be provided, and the holding member 31 may be provided. Also, as described in the third embodiment, the rotation of the rear guide 22 and the rotation of the fixing roller 11 may be interlocked.

As described above, the fixing device 1D of the fifth embodiment includes the transmission mechanism 40 that transmits the rotation of the rear guide 22 to the release cam 41, and rotates the rear guide 22 from the guide position toward the retracted position. As a result, the release cam 41 is rotated by the transmission mechanism 40 and the nip portion N is opened. Therefore, the medium P can be pulled out with less force, and the force for rotating the rear guide 22 can be small. Also, the release cam 41 can be rotated without using the power of the image forming apparatus 2 .

Although the preferred embodiments have been specifically described above, the present disclosure is not limited to the above embodiments, and various improvements and modifications can be made. Each of the above embodiments can be combined as appropriate.

The image forming apparatus of each embodiment can be used for, for example, LED printers, laser beam printers, copiers, facsimiles, MFPs (MultiFunction Peripherals), and the like.

REFERENCE SIGNS LIST 1 fixing device 2 image forming device 5 image forming unit 6 medium supply section 7 medium ejection section 11 fixing roller (fixing member) 12 pressure roller (pressure member) 13, 14 heater 15 separation claw , 16 guide roller, 17 guide surface (facing surface), 20 housing, 21 front guide, 22 rear guide (guide member), 23 rib (locking portion), 23a falling portion (first surface), 23b inclination Portion (facing portion) 23c Top portion (contacting portion) 24 Rib (locking portion) 24a Falling portion 24b Inclined portion (facing portion) 24c Top (contacting portion) 25 Rib (locking portion) 26 , 27 gripping portion 31 clamping member 32 guide rail 33 gripping portion 34 transmission mechanism (first transmission mechanism) 40 transmission mechanism (second transmission mechanism) 41 release cam (separation/contact mechanism) 45 rocking Moving frame 51 Photoreceptor drum (image carrier) 52 Charging roller (charging member) 53 Exposure head (exposure device) 54 Development roller (developer carrier) 55 Supply roller (supply member) 56 Toner cartridge (developer container) 57 transfer roller (transfer member) 101 print control unit A convex portion B concave portion.

Claims (12)

a fuser member used to heat the media;
a pressing member that is in pressure contact with the fixing member and forms a nip portion with the fixing member through which the conveyed medium passes;
a guide member provided on the downstream side of the nip portion in the medium transport direction and movable between a guide position for guiding the transported medium and a retracted position for retracting from the guide position;
the guide member has a locking portion having at least one of a convex portion and a concave portion in the medium transport direction;
The fixing device, wherein the engaging portion moves downstream in the conveying direction as the guide member moves from the guide position to the retracted position. A conveyance reference plane for the medium is defined by the guide member at the guide position,
The locking portion has a convex portion, and has a first surface extending in a direction in which a distance from the conveyance reference surface increases on a downstream side of the convex portion in the conveying direction. Item 2. The fixing device according to item 1. 3. The fixing device according to claim 2, wherein the first surface forms an obtuse angle with respect to the conveyance reference surface while the guide member moves from the guide position to the retracted position. the locking portion of the guide member is a rib extending in the conveying direction,
4. The fixing device according to claim 2, wherein the rib intersects the conveyance reference plane while the guide member moves from the guide position to the retracted position. having a facing surface that faces the guide member and defines a transport area for the medium between the guide member and the guide member;
the convex portion of the guide member has a contact portion that contacts and guides the medium when the guide member is at the guide position;
The fixing device according to any one of claims 2 to 4, wherein the contact portion approaches the facing surface while the guide member moves from the guide position to the retracted position. When a jam of the medium occurs downstream of the nip portion in the conveying direction,
3. When the guide member is moved from the guide position toward the retracted position, the first surface comes into contact with the medium and pushes the medium downstream in the transport direction. 5. The fixing device according to any one of items 1 to 5. 7. Any one of claims 1 to 6, wherein the guide member moves between the guide position and the retracted position by rotating around a spindle perpendicular to the conveying direction. The fixing device according to . further comprising a first transmission mechanism for transmitting rotation of the guide member to the fixing member;
3. The fixing member rotates so as to feed the medium downstream in the conveying direction by the first transmission mechanism when the guide member is rotated from the guide position to the retracted position. 7. The fixing device according to 7. 9. The fixing device according to claim 7, further comprising a contact/separation mechanism that causes the fixing member and the pressure member to contact or separate from each other. a second transmission mechanism for transmitting rotation of the guide member to the contact/separation mechanism;
10. When the guide member is rotated from the guide position to the retracted position, the separation and contact mechanism separates the fixing member and the pressure member from each other by the second transmission mechanism. The fixing device according to . 11. The medium according to any one of claims 1 to 10, further comprising a holding member movable between a holding position holding the medium with the guide member and a spaced position spaced apart from the guide member. 2. The fixing device according to item 1. a medium supply unit that supplies the medium;
an image forming unit that forms an image on the medium;
An image forming apparatus, comprising: the fixing device according to any one of claims 1 to 11, which fixes the image to the medium.

Images