JP4449922B2 - Fixing device - Google Patents

Description

  The present invention relates to a fixing device that fixes a toner to the recording medium by introducing the sheet-shaped recording medium onto which the toner has been transferred between two rollers. The present invention also transfers toner onto a sheet-like recording medium and introduces the recording medium onto which the toner has been transferred between two rollers to fix the toner onto the recording medium. The present invention relates to an image forming apparatus for forming an image using the toner.

  2. Description of the Related Art Conventionally, there is known a fixing device that fixes a toner to the recording medium by heating and pressing a sheet-like recording medium such as paper to which the toner is transferred. One of such fixing devices includes a heating roller and a pressure roller that presses the heating roller (see, for example, Patent Document 1). This fixing device heats and presses the recording medium by inserting the recording medium into a portion (contact portion) where the two rollers of the heating roller and the pressure roller contact each other. The fixing device further includes a guide member for guiding the recording medium in order to smoothly introduce the recording medium into the contact portion.

  By the way, when the recording medium is thick, the leading end of the guided recording medium may not smoothly enter between the two rollers. In such a case, the advance of the recording medium stops. Therefore, when a part of the rear side of the recording medium is located in a transfer device that transfers toner to the recording medium, the recording medium is not transferred into the transfer device even if the transfer device tries to convey the recording medium. Therefore, there is a problem that the actual transfer position on the recording medium is deviated from the planned position.

Therefore, in the above-described conventional fixing device, when the guide member is pushed from above (the surface side in contact with the recording medium), the guide member is close to the roller by rotating around the end portion far from the roller as the central axis of rotation. The end on the side far from the roller is rotatably supported so that the end on the side moves downward, and the lower surface of the guide member is supported by the coil spring. According to such a configuration, even when the leading edge of the recording medium stops (the recording medium is held), the recording medium bends while pushing down the guide member. Can be prevented. As a result, the recording medium can be moved as planned in the transfer device, and the actual transfer position can be prevented from deviating from the planned position.
JP 2002-278329 A

  However, according to the conventional fixing device, as the guide member is pushed down, the distance between the end of the guide member closer to the roller and the peripheral surface of the roller located below becomes smaller. Therefore, when the guide member is greatly pushed down due to a large deflection of the recording medium, the end of the guide member may come into contact with the peripheral surface of the roller, which may damage the roller or the guide member. there were. Further, in order to prevent an unfixed image due to the transferred toner from being disturbed by electrostatic force, the roller potential and the guide member potential can be reduced by grounding the roller and the guide member or applying a bias. May be at different potentials. In this case, the insulation state between the roller and the guide member may be destroyed.

  SUMMARY An advantage of some aspects of the invention is to provide a fixing device that is less likely to be damaged.

  In order to achieve such an object, the fixing device according to the present invention includes two rollers whose rotation center axes are parallel and whose peripheral surfaces are in contact with each other, and toner is transferred to a contact portion where the two rollers contact each other. The apparatus fixes the toner onto the recording medium by introducing the sheet-shaped recording medium.

One of the fixing devices according to the present invention is:
A guide member that has a contact surface in contact with the recording medium and guides the recording medium to the contact portion by the contact surface;
A displacement mechanism capable of moving the guide member in a pressing direction that is a direction from the recording medium toward the contact surface in a state where the contact surface is in contact with the recording medium;
As the guide member moves in the pressing direction, between the guide member and a proximity roller that is one of the two rollers and has a central axis of rotation closer to the pressing direction than the contact portion. distance guide member roller spacing is such that the a constant, a restriction mechanism for restricting the change of the guide member roller distance with the movement of the guide member by the displacement mechanism,
Equipped with a,
The arm member is rotatably supported by the shaft portion of the proximity roller at one end of the arm member so as to rotate with the rotation center axis of the proximity roller as a rotation center axis, and
The arm member is an end portion of the guide member in the central axis direction of rotation of the proximity roller at the other end of the arm member so that the guide member does not move relative to the arm member. It is fixed to the side surface of this .

  According to this, even if the guide member is pushed by bending of the recording medium, the distance between the guide member rollers does not become shorter than when the guide member is not pushed. Therefore, when the guide member is pushed, it can be avoided that the end of the guide member comes into contact with the peripheral surface of the proximity roller. As a result, it is possible to provide a fixing device that is less likely to be damaged.

  In addition, when the guide roller is pushed when the proximity roller and the guide member are different in potential by grounding the proximity roller or the guide member or by applying a bias, the distance between the guide member rollers By shortening, it is possible to prevent the insulation state between the proximity roller and the guide member from being broken. As a result, it is possible to provide a fixing device that is less likely to break the insulation state.

Another one of the fixing devices according to the present invention includes a regulation mechanism including a flat arm member that regulates the movement of the guide member when the guide member moves in the pressing direction.
  The arm member is one of the two rollers, and is rotated so that the rotation center axis of a proximity roller having a center axis of rotation closer to the pressing direction side than the contact portion is the center axis of rotation. At one end of the arm member, it is rotatably supported by the shaft portion of the proximity roller, and
  In the arm member, the guide member is the same around the central axis provided at the end of the guide roller on the side of the proximity roller which is parallel to the center axis of rotation of the proximity roller. The other end of the arm member is engaged with the side surface of the guide member, which is the end of the guide member in the direction of the central axis of rotation of the proximity roller, so that the relative rotation is possible.
  When the guide member moves in the pressing direction, the central shaft provided at the end of the guide member engaged with the other end of the arm member on the side of the proximity roller, the proximity roller, It is comprised so that the distance between may become constant.

According to this, when the guide member is pushed by the recording medium, the arm member rotates. At this time, the distance between the central shaft provided at the end on the proximity roller side of the guide member engaged with the other end of the arm member and the proximity roller is kept constant. The Therefore, according to the said structure, the said control mechanism can be simply provided only by providing an arm member .

Another one of the fixing devices according to the present invention is that, as the guide member moves in the pressing direction, one of the guide member and the two rollers and closer to the pressing direction side than the contact portion. Regulation that regulates the change in the distance between the guide member rollers due to the movement of the guide member by the displacement mechanism so that the distance between the guide member rollers, which is the distance between the adjacent roller having the center axis of rotation, is longer Equipped with a mechanism
Before SL restricting mechanism is a plate-like arm member,
The arm member has an end on the proximity roller side that is an end on the side of the proximity roller of the guide member when the guide member is not moved in the pressing direction at one end of the arm member. And the proximity roller at a predetermined position on a straight line (A1) passing through the rotation center axis of the proximity roller and away from the proximity roller side end from the rotation axis of the proximity roller It is configured to have a central axis of the central axis and parallel to the rotation of the rotary, and,
The arm member is an end portion of the guide member in the central axis direction of rotation of the proximity roller at the other end of the arm member so that the guide member does not move relative to the arm member. It is fixed to the side.

As the above-described configuration, by disposing the center axis of rotation of the arm member, and the proximity roller side end of the guide member, and the circumferential surface of the proximity rollers, the distance (guide member inter-roller distance) between the guide member Can be lengthened as it is pushed .

Another one of the fixing devices according to the present invention includes a regulation mechanism including a flat arm member that regulates the movement of the guide member when the guide member moves in the pressing direction.
The arm member is parallel to the rotation center axis of the proximity roller at a predetermined position on the straight line (A1) and at a predetermined position on the side away from the rotation roller axis end of the proximity roller. Having a central axis of rotation, and
Said arm member, the arm member and the guide member around "the proximity roller central axis parallel to the central axis at a by central shaft provided at an end portion of the adjacent roller side of the guide member of the rotation of the" The other end of the arm member may be engaged with the side surface of the guide member that is the end of the guide member in the direction of the central axis of rotation of the proximity roller. . According to this, when the guide member moves in the pressing direction, the central shaft provided at the end on the proximity roller side of the guide member engaged with the other end of the arm member; The distance between the proximity rollers is increased.

  As described above, when the guide member is pushed by the recording medium, the arm member rotates. Therefore, if the angle formed between the contact surface of the guide member and the arm member does not change, the angle formed by the contact surface with respect to the recording medium increases with the rotation of the arm member, and the recording medium moves to the corner (contact) of the guide member. Press the edge of the surface strongly. Thereby, the surface (back surface) on the guide member side of the recording medium is damaged. Therefore, when printing on the back side (when performing double-sided printing), the quality of the image formed on the back side may be deteriorated.

  In contrast, according to the above configuration, the contact surface of the guide member and the arm member form as the arm member rotates so that the recording medium does not strongly press the corner of the guide member even when the arm member rotates. The angle can be changed. As a result, the back surface can be prevented from being damaged, and the quality of the image formed on the back surface can be prevented from deteriorating.

  Further, when the guide member is grounded or a bias is applied to the guide member, the magnitude of the electric field is relatively large in the vicinity of the corner of the guide member. Therefore, in such a case, when the corner portion of the guide member comes into contact with the recording medium, an unfixed image by the toner transferred onto the recording medium may be disturbed by an electric field in the vicinity of the end portion.

  On the other hand, according to the above configuration, the contact surface of the guide member and the arm member are formed in accordance with the rotation of the arm member so that the corner portion of the guide member does not contact the recording medium even when the arm member rotates. The angle can be changed. Therefore, it is possible to suppress the unfixed image due to the toner transferred onto the recording medium from being disturbed by the electric field in the vicinity of the corner of the guide member.

On the other hand, in another embodiment of the fixing device according to the present invention, the guide member is formed in each of both side surfaces of the guide members is both end portions of the guide member in the direction of the central axis of rotation of the proximity rollers two Two convex portions (101a, 101a) ,
Before SL regulating mechanism, the double of the guide member to provide the two protrusions (101a, 101a) slidably contacts each guide surfaces formed on each of both side surfaces of the guide member when moving in the pressing direction It can be set as a regulating member provided with one guide long hole .
In this case, each of the guide surfaces provided by the two guide elongated holes is arranged such that the distance between the guide member rollers is constant when the guide member moves in the pressing direction . It is preferable to have an arc shape centered on the central axis of rotation .
Alternatively, the two guide elongated holes may be configured to have a linear shape parallel to each other and a shape that separates from the central axis of the proximity roller as the guide member moves in the pressing direction .

  According to this, when the guide member moves (pushes) in the pressing direction, the guide member comes into sliding contact with the guide surface. Thereby, the distance between guide member rollers when a guide member is pushed can be controlled. Therefore, according to the said structure, the said control mechanism can be simply provided only by providing a guide surface. Moreover, according to the said structure, the distance between guide member rollers with respect to the position of a guide member can be set freely.

  In these cases, it is preferable that the guide member is made of a conductive material, and a bias is applied so that the potential of the guide member is different from the polarity of the charge of the toner.

  According to this, when the recording medium is in contact with the guide member, the toner on the recording medium in the contacted portion is drawn toward the guide member. Therefore, the toner is difficult to move from the position transferred on the recording medium. As a result, it is possible to prevent the unfixed image from being transferred by the toner transferred onto the recording medium from being disturbed.

  In this case, it is preferable that the proximity roller is made of a conductive material and is grounded.

  The proximity roller is likely to be charged due to friction with the recording medium. If the proximity roller is charged and the potential of the proximity roller changes, an unfixed image by the toner transferred onto the recording medium may be disturbed. Accordingly, when the proximity roller is grounded (grounded) as in the above configuration, it is possible to prevent the proximity roller from being charged, so that an unfixed image due to the toner transferred onto the recording medium is disturbed. Can be suppressed.

<First Embodiment>
Hereinafter, a fixing device according to each embodiment of the present invention will be described with reference to the drawings. This fixing device is applied to a laser printer (image forming apparatus) 10 capable of performing color printing whose schematic cross section is shown in FIG.

  The laser printer 10 has a substantially rectangular parallelepiped shape. The laser printer 10 includes a main frame (not shown) that supports a driving force transmission mechanism including a motor that generates a driving force and a gear that transmits the driving force. Further, the laser printer 10 includes a main body casing 20 formed so as to cover the main frame, a paper feeding unit 30, a process cartridge unit 40, a scanner unit unit 50, a transfer unit 60, a fixing unit 70, A paper discharge unit 80 and a control unit 90 are included. Hereinafter, in the present specification, the right side in FIG. 1 is referred to as the “front side” of the laser printer 10, and the left side in FIG. 1 is referred to as the “back side” of the laser printer 10. Further, the upper side in FIG. 1 is called the “upper surface” side of the laser printer 10, and the lower side in FIG. 1 is called the “lower surface” side of the laser printer 10.

<< Main body casing >>
At the top of the main casing 20, a paper discharge opening 20 a is formed at a predetermined position (paper discharge position) near the end on the back side. At the top of the main casing 20, a recess 20 b is formed for holding the sheets P as sheet-like recording media discharged from the discharge opening 20 a in a stacked state.

<< Paper Feeder >>
The paper feed unit 30 includes a paper feed tray 31 and a paper transport unit 32.
The sheet feed tray 31 is a substantially rectangular parallelepiped tray that accommodates stacked sheets P. The paper feed tray 31 is open at the top. The paper feed tray 31 is detachably mounted on the bottom portion (the bottom surface portion) on the front side of the main frame. The paper feed tray 31 is provided with a paper pressing plate 31a and a separation pad 31b.

  The sheet pressing plate 31 a is a flat plate-like member having a slightly smaller area than the bottom surface of the sheet feeding tray 31. The sheet pressing plate 31 a is disposed on the bottom surface in the sheet feeding tray 31. The paper pressing plate 31a is rotatably supported by the paper feed tray 31 with the end on the back side as the central axis of rotation. The sheet pressing plate 31a is biased toward the upper side (the upper surface side of the laser printer 10) by the coil spring 31a1 at the front end.

  The separation pad 31b is a flat member. The upper surface of the separation pad 31b is made of a material that has a higher friction coefficient between the upper surface and the paper P than the friction coefficient between the paper P (in this example, a rubber material, such as polyurethane) It is also good). The separation pad 31b is disposed near the front end of the paper feed tray 31 and on the downstream side of the paper pressing plate 31a in the paper transport direction. The separation pad 31b is urged upward by a pressing spring 31c.

  The paper transport unit 32 includes a pickup roller 32a, a paper feed roller 32b, a paper transport roller 32c, a registration roller 32d, and a paper guide 32e.

  The pickup roller 32a is rotatably supported by the main frame. The pickup roller 32a is rotated by the driving force transmitted by the driving force transmission mechanism. The pickup roller 32a is located above the front end of the sheet pressing plate 31a (on the upper side of the sheet pressing plate 31a) so that the sheet P is in contact with the sheet P with a predetermined pressure when the sheet P is disposed on the sheet pressing plate 31a. ).

  The paper feed roller 32b is rotatably supported by the main frame. The paper feed roller 32b is rotated by the driving force transmitted by the driving force transmission mechanism. The paper feed roller 32b is disposed so as to face the separation pad 31b and have a peripheral surface in contact with the separation pad 31b with a predetermined pressure.

  The paper transport rollers 32c are a pair of rollers for adjusting the direction in which the paper P is transported. The paper transport rollers 32c are arranged to face each other. The paper transport roller 32c is rotatably supported by the main frame and the paper feed tray 31 on the downstream side (front side) in the paper transport direction from the separation pad 31b. One of the paper transport rollers 32c is rotated by the driving force transmitted by the driving force transmission mechanism. The other of the paper transport rollers 32c is rotated by the rotation of one of the paper transport rollers 32c.

  The registration rollers 32d are a pair of rollers similar to the paper transport rollers 32c. The registration roller 32d is rotatably supported by the main frame on the downstream side in the paper transport direction from the paper transport roller 32c. The registration roller 32d adjusts the direction in which the paper P is transported and the timing at which the paper P is transported.

  The paper guide 32e guides the paper P so that the paper P conveyed by the registration rollers 32d is conveyed toward the image forming unit (process cartridge unit 40, scanner unit unit 50, and transfer unit 60). It is a member.

  With the above-described configuration, the sheet feeding unit 30 conveys the sheet P (one sheet P at a time) toward the image forming unit in a state where the sheet P is separated from the other sheets P.

<< Process cartridge section >>
The process cartridge unit 40 includes a plurality (four in this example) of process cartridges 40Y, 40M, 40C, and 40K. Each of the process cartridges 40Y, 40M, 40C, and 40K is detachably attached to the upper part (the uppermost part) of the main frame. In this example, the process cartridges 40Y, 40M, 40C, and 40K are arranged in this order from the front side to the back side of the laser printer 10.

  The process cartridge 40Y has a substantially rectangular parallelepiped shape. The process cartridge 40Y has a toner storage space (toner box) 41 for storing toner (developer) therein. The toner storage space 41 is filled with a yellow toner that is a positively charged toner (in this example, a non-magnetic one-component toner).

  Further, a photosensitive drum 44 described later is exposed to a transfer unit 60 described later at a lower end portion (lower end portion) of the process cartridge 40Y in a state where the process cartridge 40Y is mounted on the main frame. The drum opening is formed. Further, on the back side surface of the process cartridge 40Y in the same state, an optical path for irradiating a laser beam LB output from the scanner unit 50 described later to the upper peripheral surface of the photosensitive drum 44 described later. An opening is formed.

  The process cartridge 40Y includes a supply roller 42, a developing roller 43, a photosensitive drum 44, and a charger 45. Inside the process cartridge 40Y, a supply roller 42, a developing roller 43, and a photosensitive drum 44 are rotatably supported.

  In the supply roller 42, the shaft portion of the supply roller 42 is made of a metal material, and the peripheral portion of the supply roller 42 is made of a conductive foam material. The supply roller 42 is disposed so as to face the toner storage space 41 below the toner storage space 41 (a position on the lower surface side of the toner storage space 41) when the process cartridge 40Y is mounted on the main frame. . In a state where the process cartridge 40Y is mounted on the main frame (cartridge mounted state), the supply roller 42 is rotated counterclockwise in FIG. 1 by the driving force transmitted by the driving force transmission mechanism. .

  In the developing roller 43, the shaft portion of the developing roller 43 is made of a metal material, and the peripheral portion of the developing roller 43 is made of a conductive rubber material. The developing roller 43 is disposed below the supply roller 42 so that the peripheral surface of the developing roller 43 is in contact with the peripheral surface of the supply roller 42 with a predetermined pressure. In the cartridge mounted state, the developing roller 43 is rotated counterclockwise in FIG. 1 by the driving force transmitted by the driving force transmitting mechanism. A bias is applied to the shaft portion of the developing roller 43 by being connected to a bias circuit (not shown) so that the surface potential becomes a predetermined potential for appropriately attaching toner to the peripheral surface of the photosensitive drum 44. It has become so.

  With such a configuration, toner is supplied from the toner storage space 41 onto the peripheral surface of the supply roller 42 as the supply roller 42 rotates and the development roller 43 rotates. Further, the supplied toner is positively frictionally charged between the supply roller 42 and the developing roller 43, and is held (carried) on the peripheral surface by being supplied to the peripheral surface of the developing roller 43. .

  The photosensitive drum 44 includes a cylindrical drum body and a photosensitive layer formed on the surface of the drum body. The photosensitive layer is made of a positively charged photoreceptor (in this example, polycarbonate). A part of the circumferential surface of the photosensitive drum 44 is exposed to the outside of the process cartridge 40Y from the drum opening, and a laser beam LB from the scanner unit 50, which will be described later, passes through the opening for the optical path. 1 is disposed at the lower end (the lower end of the process cartridge 40Y in a state where the process cartridge 40Y is mounted on the main frame) in FIG. Further, the photosensitive drum 44 is disposed so as to contact the developing roller 43. In the cartridge mounted state, the photosensitive drum 44 is rotated in the clockwise direction in FIG. 1 by the driving force transmitted by the driving force transmission mechanism.

  The charger 45 is a charger for positive charging (in this example, a scorotron charger). The charger 45 is connected to a bias circuit (not shown) so that a bias is applied. The charger 45 is disposed at a position upstream of the contact portion with the developing roller 43 in the rotation direction of the photosensitive drum 44 (clockwise in FIG. 1) and facing the peripheral surface of the photosensitive drum 44. ing. With this configuration, the charger 45 uniformly charges the peripheral surface of the photosensitive drum 44 positively by applying a bias.

  The process cartridges 40M, 40C, and 40K have the same configuration as the process cartridge 40Y except that the process cartridges 40M, 40C, and 40K contain toners of magenta, cyan, and black, respectively.

<< Scanner unit section >>
The scanner unit 50 includes four scanner units 50Y, 50M, 50C, and 50K corresponding to the process cartridges 40Y, 40M, 40C, and 40K, respectively.

  The scanner unit 50Y is disposed on the back side of the process cartridge 40Y so as to face the process cartridge 40Y. The scanner unit 50Y includes a polygon mirror 51, an fθ lens 52, and a reflecting mirror 53.

  The polygon mirror 51 has a polygonal column shape (in this example, a regular hexagonal column shape), and its side surface is a mirror. The polygon mirror 51 includes a polygon motor 51a. The polygon motor 51a is rotationally driven by the polygon motor 51a with the central axis of the polygon mirror 51 as a rotation central axis at a predetermined rotational speed. A side surface of the polygon mirror 51 is irradiated with a laser beam LB for yellow generated based on image data by a laser light emitting unit (not shown).

  The fθ lens 52 is coupled on a plane separated by a predetermined distance when the laser beam LB reflected by the polygon mirror 51 rotating at the predetermined rotation speed (equal angular velocity) passes through the fθ lens 52. In addition to image formation, the image formation position on the same plane moves at a constant speed.

  The reflecting mirror 53 is arranged so that the laser beam LB having passed through the fθ lens 52 is reflected so that the reflected laser beam LB is irradiated to the photosensitive drum 44 through the optical path opening.

  The scanner units 50M, 50C, and 50K have the same configuration as the scanner unit 50Y. Each of the scanner units 50M, 50C, and 50K is disposed on one back side of the corresponding process cartridge 40M, 40C, and 40K.

<< Transfer section >>
The transfer unit 60 is disposed on the lower surface side of the process cartridge unit 40 and the scanner unit unit 50. The transfer unit 60 includes a belt 61 and a transfer roller 62.

  The belt 61 is made of an elastomer. In this example, the elastomer is a synthetic rubber, and may be a synthetic resin such as polycarbonate or polyimide. The belt 61 is a seamless (endless) annular belt. The upper surface of the upper portion (upper portion) of the belt 61 that is stretched in the paper conveyance direction is in contact with the photosensitive drum 44 provided in each of the process cartridges 40Y, 40M, 40C, and 40K. Further, the inner surface of the belt 61 is supported by a belt driving roller 61a and a belt supporting roller 61b.

  The belt driving roller 61a is disposed in the vicinity of the process cartridge 40K located on the rearmost side among the plurality of process cartridges 40Y, 40M, 40C, and 40K. The belt driving roller 61a is rotatably supported by the main frame. The belt driving roller 61a is rotated by the driving force transmitted by the driving force transmission mechanism.

  The belt support roller 61b is disposed in the vicinity of the process cartridge 40Y positioned on the foremost side among the plurality of process cartridges 40Y, 40M, 40C, and 40K. The belt support roller 61b is rotatably supported by the main frame. The belt support roller 61b is configured to rotate following the circumferential movement of the belt 61 by the rotation of the belt driving roller 61a.

  The transfer roller 62 is four rollers corresponding to each of the four process cartridges 40Y, 40M, 40C, and 40K. In each transfer roller 62, the shaft portion of each transfer roller 62 is made of a metal material, and the peripheral portion of each transfer roller 62 is made of a conductive rubber material. Each transfer roller 62 is rotatably supported by the main frame. Each transfer roller 62 is rotated by the driving force transmitted by the driving force transmission mechanism. The transfer rollers 62 are arranged so as to abut each of the photosensitive drums 44 provided in the process cartridges 40Y, 40M, 40C, and 40K one by one through the upper portion of the belt 61.

  The shaft portion of each transfer roller 62 has a surface potential, and the peripheral surface of each photoconductive drum 44 in a state where the paper P carried on the belt 61 is sandwiched between the transfer roller 62 and the photoconductive drum 44. A bias is applied by connecting to a bias circuit (not shown) so that the upper toner has a predetermined potential transferred onto the surface of the paper P.

<< Fixing part >>
The fixing unit 70 is disposed on the downstream side of the transfer unit 60 in the sheet conveyance direction. The fixing unit 70 is shown in FIG. 1, FIG. 2 which is a perspective view from above the fixing unit 70, FIG. 3 which is a side view of the fixing unit 70, and FIG. 4 which is a perspective view from below the fixing unit 70. In addition, a heating roller 71, a pressure roller 72, a guide member 73, an arm member 74, and a cleaning roller 75 are provided.

  The heating roller 71 has a hollow cylindrical shape. The heating roller 71 is made of metal. The peripheral surface of the heating roller 71 is subjected to mold release processing (in this example, coating with a fluororesin). The heating roller 71 accommodates a halogen lamp (not shown) therein. The halogen lamp generates heat when connected to a power supply circuit (not shown). The heating roller 71 is rotatably supported by the main frame. The heating roller 71 rotates in the clockwise direction in FIG. 1 by the driving force transmitted by the driving force transmission mechanism. The heating roller 71 is grounded (grounded) via a grounding conductor (not shown).

  In the pressure roller 72, the shaft portion of the pressure roller 72 is made of a metal material, and the peripheral portion of the pressure roller 72 is made of a conductive rubber material. The peripheral surface of the pressure roller 72 is subjected to mold release processing (in this example, coating with a fluororesin). The pressure roller 72 is disposed below the heating roller 71 so as to be pressed against the heating roller 71 with a predetermined pressure. That is, the peripheral surface of the pressure roller 72 and the peripheral surface of the heating roller 71 are in contact with each other.

  The pressure roller 72 is rotatably supported by the main frame so that the central axis of rotation of the pressure roller 72 is parallel to the central axis of rotation of the heating roller 71. The pressure roller 72 is rotated counterclockwise in FIG. 1 following the rotation of the heating roller 71. The shaft portion of the pressure roller 72 is grounded (grounded) via a grounding conductor (not shown).

  The guide member 73 is a flat member. The guide member 73 is made of metal. The upper surface of the guide member 73 supports the peripheral surface of the heating roller 71 and the peripheral surface of the pressure roller 72 while supporting the paper P from the back surface side opposite to the surface on which the toner is transferred (in contact with the back surface of the paper P). The sheet P is formed so as to guide the sheet P to a contact portion (nip portion) where the surfaces contact each other. That is, the upper surface of the guide member 73 constitutes a contact surface in contact with the paper P (recording medium). The lower surface of the guide member 73 is supported by a coil spring SP.

With such a configuration, the guide member 73 is pushed in a pressing direction (downward) that is a direction from the paper P toward the contact surface in a state where the upper surface (contact surface) of the guide member 73 is in contact with the paper P ( When pressed down, the coil spring SP is compressed. In this way, the coil spring SP can move the guide member 73 in the pressing direction. That is, the coil spring SP constitutes a displacement mechanism.
The guide member 73 is biased by being connected to a bias circuit (not shown) so that the potential becomes a negative polarity potential (-1000 V in this example) different from the polarity of the charge (that is, positive polarity) of the toner. Is applied.

  Further, hereinafter, in this specification, the pressure roller 72 which is one of the two rollers of the heating roller 71 and the pressure roller 72 and has a central axis of rotation on the pressing direction side with respect to the contact portion is referred to as a proximity roller. Call it.

  The arm member 74 is a pair of flat members. The arm member 74 is made of metal. The pair of arm members 74 are disposed so as to face each other. The base end side portion (base end portion, one end portion) of each arm member 74 can be rotated by the shaft portion of the pressure roller 72 one by one at both ends in the central axis direction of the pressure roller 72. It is supported by. A sheet-like insulator is interposed at a portion where the arm member 74 and the shaft portion of the pressure roller 72 are in contact with each other. The central axis of rotation of each arm member 74 is coaxial with the central axis of rotation of the proximity roller (pressure roller 72). The front end portion (the front end portion and the other end portion) of each arm member 74 is fixed to the side surfaces constituting both ends of the guide member 73 in the central axis direction (paper width direction) of the rotation of the pressure roller 72. . That is, the distal end portion of each arm member 74 and the end portion on the proximity roller side (proximity roller side end portion) of the guide member 73 are fixed to each other so as not to move relative to each other.

  With this configuration, when the guide member 73 moves in the pressing direction, the distance between the guide member 73 and the proximity roller (pressure roller 72) (distance between the guide member rollers) is maintained constant. That is, the arm member 74 constitutes a regulation mechanism that regulates a change in the distance between the guide member rollers accompanying the movement of the guide member 73 by the displacement mechanism.

  In this example, the cleaning roller 75 is four rollers as shown in FIG. Each cleaning roller 75 is made of resin (in this example, polyphenylene sulfide (PPS) resin). A plurality of spiral grooves coaxial with the central axis of the cleaning roller 75 are formed on the peripheral surface of each cleaning roller 75. The cleaning roller 75 is disposed so as to be in contact with the pressure roller 72 with a predetermined pressure and so that the interval between them is substantially equal in the paper width direction. Each cleaning roller 75 is rotatably supported by the main frame (a member fixed to the main frame). Each cleaning roller 75 rotates in the clockwise direction in FIG. 1 following the rotation of the pressure roller 72.

  The cleaning roller 75 having such a configuration removes toner from the peripheral surface of the pressure roller 72 by scraping the toner adhering to the peripheral surface of the pressure roller 72 while being accommodated in the groove. At this time, since the spiral groove is formed on the peripheral surface of the cleaning roller 75, it is difficult to prevent the rotation of the pressure roller 72. Therefore, the possibility of damaging the pressure roller 72 can be reduced as compared with the case where a linear groove having a longitudinal axis parallel to the central axis of the cleaning roller 75 is formed.

<< Output section >>
Continuing the description with reference to FIG. 1 again, the paper discharge unit 80 is disposed on the rearmost side of the laser printer 10. The paper discharge unit 80 includes a paper discharge guide 81 and a paper discharge roller 82.

The paper discharge guide 81 is a member that guides (guides) the paper P conveyed by the fixing unit 70 toward the paper discharge roller 82.
The paper discharge rollers 82 are a pair of rollers for discharging the paper P to the upper surface of the laser printer 10. The paper discharge rollers 82 are disposed to face each other in the vicinity of the paper discharge opening 20a. The paper discharge roller 82 is rotatably supported by the main frame. One of the paper discharge rollers 82 is rotated by the driving force transmitted by the driving force transmission mechanism. The other of the paper discharge rollers 82 is rotated by the rotation of one of the paper discharge rollers 82.

<< Control part >>
The control unit 90 is disposed at the bottom side of the main frame and on the back side of the sheet feeding unit 30. The control unit 90 includes various motors, actuators, and sensors provided in the main frame for driving the movable units of the laser printer 10, laser emission units and polygon motors 51a provided in the scanner unit 50, and the like. Various bias circuits and various power supply circuits are electrically connected to each other, and an instruction signal is sent to them at a predetermined timing.

<Operation>
Next, the operation of the laser printer 10 configured as described above will be described from the time when the user sends a print instruction signal including image data to the laser printer 10.

  When the control unit 90 receives the print instruction signal, the control unit 90 supplies the process cartridges 40Y, 40M, 40C, and 40K with the supply roller 42, the developing roller 43, and the photosensitive drum 44, and the scanner units 50Y, 50M, and 50C. The polygon mirror 51 of 50K, the belt drive roller 61a of the transfer unit 60, the heating roller 71 of the fixing unit 70, and the paper discharge roller 82 of the paper discharge unit 80 are controlled to be in a rotating state (rotation state). .

  Further, the control unit 90 controls the chargers 45 of the process cartridges 40Y, 40M, 40C, and 40K to a state where a bias is applied (bias application state). As a result, the peripheral surface of the photoconductive drum 44 starts to be positively (positively charged). Then, after a predetermined time has elapsed, the peripheral surface of the photoconductive drum 44 is positively and uniformly charged. That is, the potential on the peripheral surface of the photosensitive drum 44 is a positive potential.

  Further, the control unit 90 controls each roller of the paper transport unit 32 of the paper feeding unit 30 to be in a rotating state. Thus, the paper P is conveyed toward the image forming unit in a state of being separated from the other paper P (one by one).

  When the leading edge of the paper P reaches a predetermined position in the paper guide 32e, the control unit 90 can output the laser beam LB from the laser light emitting units of the scanner units 50Y, 50M, 50C, and 50K (light emission). Control to ready state.

  Further, the control unit 90 controls the developing roller 43, the transfer roller 62, and the guide member 73 of the fixing unit 70 to a bias application state. In addition, the control unit 90 controls the halogen lamp to generate heat (heat generation state). Thereby, the surface of the heating roller 71 becomes a high temperature state.

  Thereafter, the control unit 90 causes the laser light emitting units of the scanner units 50Y, 50M, 50C, and 50K to move the position on the peripheral surface of the photosensitive drum 44 scanned by the laser beam LB from the current position to the transfer processing position (photosensitive). Time until the body drum 44 and the transfer roller 62 abut each other via the belt 61) and the transfer position on the paper P to which a part of the image corresponding to the scanning is to be transferred is the current position. The laser beam LB is output on the basis of the image data at a timing when the time from the transfer to the transfer processing position coincides.

  The output laser beam LB is reflected by the side surface of the rotating polygon mirror 51, passes through the fθ lens 52 and is reflected by the reflecting mirror 53, and forms an image on the peripheral surface of the photosensitive drum 44. Thereby, the peripheral surface is exposed at a position where the laser beam LB forms an image. As a result, the surface potential is lowered at the same exposed position, and an electrostatic latent image is formed on the circumferential surface.

  When the electrostatic latent image formed on the peripheral surface of the photosensitive drum 44 comes into contact with the peripheral surface of the developing roller 43, the toner held on the peripheral surface of the developing roller 43 is transferred to the photosensitive drum 44. Move towards the circumference. The moved toner adheres only to a position on the peripheral surface of the photosensitive drum 44 and exposed (exposed) by the laser beam LB. In this manner, the electrostatic latent images formed on the peripheral surfaces of the photosensitive drums 44 of the process cartridges 40Y, 40M, 40C, and 40K are developed with toner.

  On the other hand, when the paper P reaches the belt 61, the paper P is conveyed while being supported by the belt 61. When the paper P reaches the transfer processing position (between the photosensitive drum 44 and the transfer roller 62 via the belt 61), the circumferential surface of the photosensitive drum 44 at the transfer processing position. The toner adhering to the top moves onto the paper P and adheres to the paper P. In this way, the toner image developed on the peripheral surface of the photosensitive drum 44 is transferred onto the paper P. At this time, images of the respective color toners are sequentially superimposed and transferred by the process cartridges 40Y, 40M, 40C, and 40K.

  Next, when the sheet P reaches the guide member 73, the sheet P moves toward the contact portion (nip portion) where the peripheral surface of the heating roller 71 and the peripheral surface of the pressure roller 72 contact each other. Guided by the contact surface.

  Incidentally, the toner is positively charged, while the potential of the guide member 73 is a negative potential. Therefore, when the paper P is supported by the guide member 73 (in contact with the guide member 73), the toner on the paper P in the supported (contacted) portion is attracted toward the guide member 73. . This makes it difficult for the toner to move from the position transferred onto the paper P. As a result, it is possible to prevent the unfixed image from being transferred by the toner transferred onto the paper P from being disturbed.

  Then, when the paper P is introduced into the contact portion and sandwiched between the peripheral surface of the heating roller 71 and the peripheral surface of the pressure roller 72, the toner transferred onto the paper P is heated and pressed. Is done. As a result, the toner transferred onto the paper P is fixed on the paper P.

  Further, as described above, the heating roller 71 and the pressure roller 72 are each grounded. Therefore, it is possible to prevent the heating roller 71 and the pressure roller 72 from being charged due to friction with the paper P or the like. As a result, it is possible to suppress the unfixed image due to the toner transferred onto the paper P due to the charging of the heating roller 71 and the pressure roller 72 from being disturbed (occurrence of color misregistration).

  Thereafter, when the paper P is guided by the paper discharge guide 81 and reaches the paper discharge roller 82, the paper P is discharged onto the upper surface of the laser printer 10 by the paper discharge roller 82.

  When the discharge of the paper P is completed, the control unit 90 stops the rotation of each roller and the polygon mirror 51 that are controlled to be rotated. Furthermore, the control unit 90 controls the laser light emitting unit to a state where the laser beam LB is not output (non-light emitting state). In addition, the control unit 90 controls the charger 45, the developing roller 43, and the transfer roller 62 that are controlled to be in a bias application state so that a bias is not applied (a bias non-application state). In addition, the control unit 90 controls the halogen lamp so as not to generate heat (non-heat generation state).

  In this manner, the laser printer 10 forms an image represented by the image data included in the print instruction signal sent by the user on the paper P (prints on the paper P).

  Next, when the paper P is thick and the paper P is not smoothly introduced into the contact portion between the heating roller 71 and the pressure roller 72 (that is, the front end of the paper P advances in the vicinity of the contact portion). The advantages of this embodiment in the case of stopping the operation will be described in comparison with a conventional fixing device.

  As shown in FIGS. 11 and 12, the conventional fixing device (fixing unit) 900 is similar to the fixing device (fixing unit) 70 according to this embodiment, and includes a heating roller 901, a pressure roller 902, and a guide member 903. It has. In the conventional fixing unit 900, the guide member 903 is an end portion of the guide member 903, and an end portion RP far from the pressure roller 902 (proximity roller) can be rotated by a main frame (a member fixed to the main frame). It is supported by. Further, the conventional fixing unit 900 does not include the arm member 74 included in the fixing unit 70 of the present embodiment.

  In the conventional fixing unit 900, when the paper P is not smoothly introduced into the contact portion between the heating roller 901 and the pressure roller 902 as described above, a part of the rear of the paper P is conveyed by the photosensitive drum and the belt. Accordingly, the sheet P bends while pushing down the guide member 903 as shown in FIG.

  At this time, the guide member 903 rotates with the end portion RP far from the proximity roller as the central axis of rotation. Accordingly, as the guide member 903 is largely pushed down, the distance (the distance between the guide member rollers) D between the end portion of the guide member 903 closer to the proximity roller (end portion on the proximity roller side) and the proximity roller becomes shorter. Become.

  Accordingly, when the guide member 903 is largely pushed down due to the large deflection of the paper P, the end portion of the guide member 903 comes into contact with the peripheral surface of the pressure roller 902, so that the pressure roller 902 and the guide member 903 are the same. Could be damaged. In addition, when the distance D between the guide member rollers is shortened, the insulation state between the pressure roller 902 and the guide member 903 may be destroyed.

  On the other hand, in the case of the present embodiment, as shown in FIG. 5, when the sheet P bends while pushing down the guide member 73, the arm member 74 rotates with the central axis of rotation of the pressure roller 72 as the central axis of rotation P <b> 1. To do. Further, as described above, the tip end portion of the arm member 74 and the end portion on the proximity roller side of the guide member 73 are fixed to each other so as not to move relative to each other. Therefore, when the guide member 73 is pushed down, the distance D between the proximity roller side end portion of the guide member 73 and the proximity roller (distance between the guide member rollers) D is maintained constant. That is, even when the guide member 73 is largely pushed down, the guide member roller distance D is not shortened.

  Therefore, when the guide member 73 is pushed down, it can be avoided that the end of the guide member 73 comes into contact with the peripheral surface of the proximity roller. As a result, it is possible to provide the fixing unit 70 in which the pressure roller 72 is less likely to be damaged by the guide member 73. Furthermore, since the distance D between the guide member rollers is shortened, it is possible to prevent the insulation state between the pressure roller 72 (proximity roller) and the guide member 73 from being broken.

  In addition, according to the present embodiment, when the paper P is not smoothly introduced into the contact portion, the paper P can be bent, so that the conveyance of the paper P in the transfer portion 60 is prevented from being hindered. be able to. As a result, the paper P can be moved as planned in the transfer unit 60, and the actual transfer position can be prevented from deviating from the planned position.

  As described above, according to the first embodiment of the fixing device according to the present invention, even if the guide member 73 is pushed down by bending the paper P, the distance D between the guide member rollers can be maintained constant. Therefore, it is possible to provide a fixing device that is less likely to be damaged.

  Further, according to the first embodiment, it is possible to simply provide a restriction mechanism that maintains the distance D between the guide member rollers when the guide member 73 is pushed down by simply providing the arm member 74. Furthermore, according to the first embodiment, since it is not necessary to provide the rotation center axis P1 of the arm member 74 in addition to the rotation center axis of the proximity roller, the configuration of the restriction mechanism can be simplified.

  In the first embodiment, the central axis of rotation of the arm member 74 is arranged so as to be coaxial with the central axis of rotation of the proximity roller. However, as shown in FIG. 3 on the straight line L1 passing through the adjacent roller side end and the central axis of rotation of the adjacent roller, and away from the adjacent roller side end (arrow A1 in FIG. 3). 3) (position on the broken line portion of the straight line L1 in FIG. 3, for example, Px, Py, etc.) and may be arranged in parallel with the central axis of rotation of the proximity roller. .

  According to this, the arm member 74 can easily configure a restricting mechanism that increases the distance D between the guide member rollers as the guide member 73 moves downward (as it is largely pushed down).

  In the first embodiment, the tip of the arm member 74 is fixed so as not to rotate relative to the guide member 73. However, as shown in FIG. The angle formed between the contact surface of the guide member 73 and the arm member 74 is changed by rotating the guide member 73 with respect to the arm member 74 using a straight line parallel to the rotation center axis of the passing roller and the rotation center axis P2. In order to be possible, it may be fixed to the end portion on the side of the adjacent roller so as to be relatively rotatable.

  According to this, when the arm member 74 rotates as the paper P is bent and the guide member 73 is pushed down, the guide member 73 rotates with the central axis P2 as the central axis of rotation as the arm member 74 rotates. It rotates with respect to the arm member 74. As a result, the contact surface of the guide member 73 is substantially parallel to the paper P. As a result, the sheet P is not strongly pressed by the corner portion of the guide member 73 at the end portion on the proximity roller side. Therefore, it is possible to prevent the back surface of the paper P from being damaged, and it is possible to prevent the quality of the image formed on the back surface from deteriorating when printing is performed on the back surface. Further, it is possible to suppress the unfixed image due to the toner transferred on the paper P from being disturbed by a strong electric field that is likely to occur in the vicinity of the same angle portion.

<Second Embodiment>
Next, a fixing device according to a second embodiment of the present invention will be described. The fixing device according to the second embodiment differs from the fixing unit 70 according to the first embodiment only in that a fixing member is provided in place of the arm member 74 of the first embodiment. Hereinafter, this difference will be mainly described.

  7 to 9, the fixing unit 70 includes a guide member 101 that replaces the guide member 73 according to the first embodiment, and a regulating member 102 that replaces the arm member 74 according to the first embodiment. .

  The guide member 101 has the same configuration as the guide member 73 according to the first embodiment. In addition, two columnar convex portions 101a are formed on each side surface of the guide member 101 constituting both ends of the guide member 101 in the paper width direction.

  As shown in FIG. 7, the regulating member 102 is a pair of flat members. The restriction member 102 is fixed to the main frame (a member fixed to the main frame). The restricting members 102 are disposed so as to face each other with the guide member 101 interposed therebetween in the sheet width direction.

  As shown in FIG. 8, which is an enlarged perspective view of the regulating member 102, each regulating member 102 is formed with two slit-shaped guide holes 102a and 102b penetrating in the thickness direction. A pair of long hole wall surfaces 102a1 and 102b1 along the longitudinal direction of each of the guide long holes 102a and 102b are wall surfaces parallel to the thickness direction of the regulating member 102. The distance between the pair of wall surfaces of the long hole wall surfaces 102a1 and 102b1 is substantially the same as the diameter of the convex portion 101a.

  As shown in FIG. 9 which is a side view of the fixing unit 70, in the state where the regulating member 102 is fixed to the main frame, the pair of long hole wall surfaces 102a1 is the center of rotation of the pressure roller 72 (proximity roller). They are located on two cylindrical surfaces having radii r1 and r2 with the axis as the central axis. In the same state, the pair of long hole wall surfaces 102b1 have radii r3 and r4 (r4> r3> r2> r1) that are coaxial with the two cylindrical surfaces of the long hole wall surface 102a1 and larger than any cylindrical surface of the long hole wall surface 102a1. Each is located on two cylindrical surfaces. That is, each of the long hole wall surfaces 102a1 and 102b1 has an arc shape centering on the central axis of rotation of the proximity roller in the side view of the fixing unit 70.

  Each regulating member 102 accommodates two convex portions 101a of the guide member 101 one by one in each guide slot 102a, 102b.

  In the fixing unit 70 configured as described above, when the guide member 101 is pushed down, the convex portion 101a of the guide member 101 is in sliding contact (sliding) with the long hole wall surfaces 102a1 and 102b1 (particularly the wall surface on the proximity roller side). Move). Thereby, the guide member 101 moves in the pressing direction while maintaining the distance D between the guide member rollers constant. The long hole wall surfaces 102a1 and 102b1 of the regulating member 102 constitute a guide surface.

  As a result, as in the first embodiment, even if the guide member 101 is pushed down by bending the paper P, the distance D between the guide member rollers can be maintained constant, so that there is little risk of damage. A fixing device can be provided.

  Further, according to the second embodiment, it is possible to simply provide the restriction mechanism simply by including the restriction member 102 having the guide surface.

In the second embodiment, the guide long holes 102a and 102b formed by the long hole wall surfaces 102a1 and 102b1 having an arc shape in the side view of the fixing unit 70 are formed in the regulating member 102. As shown in FIG. 10, the guide long holes 103 a and 103 b configured by the long hole wall surfaces 103 a 1 and 103 b 1 which are linear shapes parallel to each other in a side view of the fixing unit 70 may be formed in the restriction member 103. In this case, the distance D between the guide member rollers becomes longer as the guide member 101 is largely pushed down.
As described above, when the restriction mechanism is configured by the restriction member having the guide surface, the distance D between the guide member rollers with respect to the position of the guide member 101 can be freely set.

  In addition, this invention is not limited to said each embodiment, A various modification can be employ | adopted within the scope of the present invention. For example, the fixing device in each of the above embodiments may be applied to a laser printer that includes one process cartridge and one scanner unit and performs only monochrome printing.

1 is a schematic sectional side view of a laser printer to which a fixing device (fixing unit) according to a first embodiment of the present invention is applied. FIG. 2 is a perspective view from above of the fixing unit illustrated in FIG. 1. FIG. 2 is a side view of the fixing unit illustrated in FIG. 1. FIG. 2 is a perspective view from below of a fixing unit illustrated in FIG. 1. FIG. 2 is a side view of the fixing unit illustrated in FIG. 1. FIG. 9 is a side view of a fixing unit according to a modification of the first embodiment of the present invention. It is a perspective view from the upper part of the fixing part which concerns on 2nd Embodiment of this invention. FIG. 8 is an enlarged perspective view of the regulating member shown in FIG. 7. FIG. 8 is a side view of the fixing unit illustrated in FIG. 7. FIG. 10 is a side view of a fixing unit according to a modification of the second embodiment of the present invention. FIG. 6 is a perspective view from above of a conventional fixing device (fixing unit). FIG. 12 is a side view of the fixing unit illustrated in FIG. 11. FIG. 12 is a side view of the fixing unit illustrated in FIG. 11.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Laser printer, 40 ... Process cartridge part, 40Y, 40M, 40C, 40K ... Process cartridge, 44 ... Photosensitive drum, 50 ... Scanner unit part, 50Y, 50M, 50C, 50K ... Scanner unit, 60 ... Transfer part, DESCRIPTION OF SYMBOLS 61 ... Belt, 62 ... Transfer roller, 70 ... Fixing part, 71 ... Heating roller, 72 ... Pressure roller, 73 ... Guide member, 74 ... Arm member, 75 ... Cleaning roller, 80 ... Paper discharge part, 90 ... Control part , 101 ... Guide member, 101a ... Convex portion, 102 ... Regulator member, 102a, 102b ... Guide slot, 102a1, 102b1 ... Long hole wall surface, 103 ... Regulator member, 103a, 103b ... Guide slot, 103a1, 103b1 ... wall surface of long hole, 900 ... fixing section, 901 ... heating roller, 902 ... pressure roller, 903 ... guide member, B ... laser beam, P ... paper, SP ... coil spring.

Claims (8)

The two toners are provided by introducing a sheet-like recording medium onto which the toner is transferred to a contact portion where the two rollers are in contact with each other, the rotation axes of which are parallel and the peripheral surfaces of which are in contact with each other. A fixing device for fixing the image on the recording medium,
A flat guide member having a contact surface in contact with the recording medium and guiding the recording medium to the contact portion by the contact surface;
A displacement mechanism capable of moving the guide member in a pressing direction that is a direction from the recording medium toward the contact surface in a state where the contact surface is in contact with the recording medium;
When the guide member moves in the pressing direction, between the guide member and a proximity roller that is one of the two rollers and has a central axis of rotation closer to the pressing direction than the contact portion. A regulation mechanism for regulating a change in the distance between the guide member rollers due to the movement of the guide member by the displacement mechanism, so that the distance between the guide member rollers, which is a distance, is constant;
In the fixing device provided with
The restriction mechanism is a flat arm member,
The arm member is rotatably supported by the shaft portion of the proximity roller at one end of the arm member so as to rotate with the rotation center axis of the proximity roller as a rotation center axis, and
The arm member is an end portion of the guide member in the central axis direction of rotation of the proximity roller at the other end of the arm member so that the guide member does not move relative to the arm member. A fixing device characterized in that the fixing device is fixed to a side surface of the fixing device. The two toners are provided by introducing a sheet-like recording medium onto which the toner is transferred to a contact portion where the two rollers are in contact with each other, the rotation axes of which are parallel and the peripheral surfaces of which are in contact with each other. A fixing device for fixing the image on the recording medium,
A flat guide member having a contact surface in contact with the recording medium and guiding the recording medium to the contact portion by the contact surface;
A displacement mechanism capable of moving the guide member in a pressing direction that is a direction from the recording medium toward the contact surface in a state where the contact surface is in contact with the recording medium;
A restriction mechanism for restricting movement of the guide member when the guide member moves in the pressing direction;
In the fixing device provided with
The restriction mechanism is a flat arm member,
The arm member is the same as one of the two rollers, and rotates with a rotation center axis of a proximity roller having a rotation center axis closer to the pressing direction than the contact portion as a rotation center axis. At one end of the arm member, it is rotatably supported by the shaft portion of the proximity roller, and
The arm member has a central axis that is parallel to a central axis of rotation of the proximity roller, and is relatively opposite to the arm member around a central axis provided at an end of the guide member on the proximity roller side. The other end of the arm member is engaged with the side surface of the guide member that is the end of the guide member in the direction of the central axis of rotation of the proximity roller so that the arm member can rotate .
When the guide member moves in the pressing direction, the central shaft provided at the end of the guide member engaged with the other end of the arm member on the side of the proximity roller, the proximity roller, A fixing device characterized in that the distance between the two is constant . The two toners are provided by introducing a sheet-like recording medium onto which the toner is transferred to a contact portion where the two rollers are in contact with each other, the rotation axes of which are parallel and the peripheral surfaces of which are in contact with each other. A fixing device for fixing the image on the recording medium,
A flat guide member having a contact surface in contact with the recording medium and guiding the recording medium to the contact portion by the contact surface;
A displacement mechanism capable of moving the guide member in a pressing direction that is a direction from the recording medium toward the contact surface in a state where the contact surface is in contact with the recording medium;
As the guide member moves in the pressing direction, between the guide member and a proximity roller that is one of the two rollers and has a central axis of rotation closer to the pressing direction than the contact portion. A regulation mechanism for regulating a change in the distance between the guide member rollers due to the movement of the guide member by the displacement mechanism, so that the distance between the guide member rollers, which is a distance, is increased;
In the fixing device provided with
The restriction mechanism is a flat arm member,
The arm member has an end on the proximity roller side that is an end on the side of the proximity roller of the guide member when the guide member is not moved in the pressing direction at one end of the arm member. And a predetermined position on a straight line (A1) passing through the rotation center axis (P1) of the proximity roller and away from the rotation roller central axis. It is configured to have a central axis of rotation parallel to the central axis of rotation of the proximity roller, and
The arm member is an end portion of the guide member in the central axis direction of rotation of the proximity roller at the other end of the arm member so that the guide member does not move relative to the arm member. A fixing device characterized in that the fixing device is fixed to a side surface of the fixing device. The two toners are provided by introducing a sheet-like recording medium onto which the toner is transferred to a contact portion where the two rollers are in contact with each other, the rotation axes of which are parallel and the peripheral surfaces of which are in contact with each other. A fixing device for fixing the image on the recording medium,
A flat guide member having a contact surface in contact with the recording medium and guiding the recording medium to the contact portion by the contact surface;
A displacement mechanism capable of moving the guide member in a pressing direction that is a direction from the recording medium toward the contact surface in a state where the contact surface is in contact with the recording medium;
A restriction mechanism for restricting movement of the guide member when the guide member moves in the pressing direction;
In the fixing device provided with
The restriction mechanism is a flat arm member,
The arm member is a central axis (P1) of rotation of a proximity roller having a central axis of rotation at one end of the arm member, which is one of the two rollers and closer to the pressing direction than the contact portion. ) And a proximity roller side end that is an end on the proximity roller side of the guide member when the guide member is not moved in the pressing direction at a predetermined position on a straight line (A1). A rotation center axis parallel to the rotation center axis of the proximity roller at a predetermined position on the side away from the rotation roller end axis of the proximity roller,
The arm member has a central axis that is parallel to a central axis of rotation of the proximity roller, and is relatively opposite to the arm member around a central axis provided at an end of the guide member on the proximity roller side. The other end of the arm member is engaged with the side surface of the guide member that is the end of the guide member in the direction of the central axis of rotation of the proximity roller so that the arm member can rotate .
When the guide member moves in the pressing direction, the central shaft provided at the end of the guide member engaged with the other end of the arm member on the side of the proximity roller, the proximity roller, A fixing device characterized in that the distance between them is increased . The two toners are provided by introducing a sheet-like recording medium onto which the toner is transferred to a contact portion where the two rollers are in contact with each other, the rotation axes of which are parallel and the peripheral surfaces of which are in contact with each other. A fixing device for fixing the image on the recording medium,
A flat guide member having a contact surface in contact with the recording medium and guiding the recording medium to the contact portion by the contact surface;
A displacement mechanism capable of moving the guide member in a pressing direction that is a direction from the recording medium toward the contact surface in a state where the contact surface is in contact with the recording medium;
When the guide member moves in the pressing direction, between the guide member and a proximity roller that is one of the two rollers and has a central axis of rotation closer to the pressing direction than the contact portion. A regulation mechanism for regulating a change in the distance between the guide member rollers due to the movement of the guide member by the displacement mechanism, so that the distance between the guide member rollers, which is a distance, is constant;
In the fixing device provided with
The guide member has two convex portions formed on each of both side surfaces of the guide members is both end portions of the guide member in the direction of the central axis of rotation of the proximity rollers (101a, 101a),
The restricting mechanism provides two guide surfaces on which the two convex portions (101a, 101a) formed on both side surfaces of the guide member respectively slide in contact with each other when the guide member moves in the pressing direction . It is a regulating member provided with a guide hole (102a, 102b) , and
Each of the guide surfaces provided by the two guide elongated holes has a center of rotation of the proximity roller so that the distance between the guide member rollers is constant when the guide member moves in the pressing direction. A fixing device configured to have an arc shape centered on an axis . The two toners are provided by introducing a sheet-like recording medium onto which the toner is transferred to a contact portion where the two rollers are in contact with each other, the rotation axes of which are parallel and the peripheral surfaces of which are in contact with each other. A fixing device for fixing the image on the recording medium,
A flat guide member having a contact surface in contact with the recording medium and guiding the recording medium to the contact portion by the contact surface;
A displacement mechanism capable of moving the guide member in a pressing direction that is a direction from the recording medium toward the contact surface in a state where the contact surface is in contact with the recording medium;
As the guide member moves in the pressing direction, between the guide member and a proximity roller that is one of the two rollers and has a central axis of rotation closer to the pressing direction than the contact portion. A regulation mechanism for regulating a change in the distance between the guide member rollers due to the movement of the guide member by the displacement mechanism, so that the distance between the guide member rollers, which is a distance, is increased;
In the fixing device provided with
The guide member has two protrusions formed on each of both side surfaces of the guide members is both end portions of the guide member in the direction of the central axis of rotation of the proximity rollers (101a, 101a),
The regulating mechanism, the double of the said two projections formed on each of both side surfaces of the guide member when the guide member is moved in the pressing direction (101a, 101a) is provided by each of the sliding contact guide surface A restricting member having two elongated guide holes (103a, 103b) ;
The guide long hole (103a, 103b), said convex portion when the guide member is moved in the pressing direction (101a, 101a) by the contact of the guide surface and sliding, in the guide member the pressing direction A linear shape parallel to each other so that the distance between the guide member rollers becomes longer as the guide member moves, and a shape that separates from the central axis of the proximity roller as the guide member moves in the pressing direction. A fixing device characterized by being configured. The fixing device according to any one of claims 1 to 6,
The fixing device, wherein the guide member is made of a conductive material, and a bias is applied so that the potential of the guide member is different from the polarity of the charge of the toner. The fixing device according to any one of claims 1 to 7,
The proximity roller is made of a conductive material and is grounded.

Images