JPH0524931Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Technical Field> The present invention relates to a toner image fixing device applied to an electrostatic copying device or the like.

<Prior Art> Conventionally, for example, in electrostatic copying machines,
A toner image fixing device that includes a driven fixing roller that is rotated in a predetermined direction and a driven fixing roller that is pressed against the driven fixing roller in order to fix the toner image formed on the sheet member on the surface of the sheet member. The device is in practical use. The driven fixing roller and the driven fixing roller are arranged in such a way as to prevent deformation of both rollers due to pressure contact, or to facilitate removal of the jammed sheet member when the sheet member is jammed between the two rollers. The rollers are configured to be selectively brought into an operative state in which the rollers are pressed against each other and a non-operative state in which the pressed state of both rollers is released. In such a toner image fixing device, a sheet member having a toner image is conveyed between an active driven fixing roller and a driven fixing roller, and the toner image is fixed on the surface of the sheet member during such conveyance.

Such a toner image fixing device further includes an upper separation mechanism disposed in association with the driven fixing roller to guide the sheet member sent out from the driven fixing roller and the driven fixing roller to the downstream side in a predetermined manner. A lower separation mechanism is provided associated with the driven fuser roller. The upper separating mechanism has an upper separating claw that acts on the surface of the driven fixing roller, and the action of the upper separating claw prevents the sheet member from being wrapped around the driven fixing roller, and the lower separating mechanism has a driven fixing roller. It has a lower separating claw that acts on the surface of the fixing roller, and the action of the lower separating claw prevents the sheet member from being wrapped around the driven fixing roller.

However, in conventional toner image fixing devices of this kind, the driven fixing roller and the upper separating mechanism are generally installed between the supporting side walls of the fixing device in a predetermined relationship, so there is a problem with the upper separating mechanism. However, on the other hand, the driven fixing roller is supported so as to be movable toward and away from the driven fixing roller, and the lower separation mechanism is a part that is substantially unrelated to the movement of the driven fixing roller (for example, Because the lower separation mechanism is located between the support side walls or between the vertical substrates of an electrostatographic apparatus, the following problems exist with respect to the lower separation mechanism. That is, at the time of design, the rotation center axis of the driven fixing roller in the operating state and the rotation center axis of the lower separation claw are set to have a predetermined relationship, but after the device is assembled,
Due to manufacturing errors, assembly errors, variations in hardness of the driven fixing roller, etc., the distance between the rotational center axis and the turning center axis in the operating state varies.
Thus, the contact angle of the lower separation claw (the angle between the common tangent at the contact point of the separation claw and the driven fixing roller and the straight line connecting the contact point and the rotation center axis)
If the contact angle changes and the contact angle cannot be maintained at a predetermined set value, and the contact angle increases beyond the allowable range, the tip of the lower separation claw will bite into the surface of the driven fixing roller relatively largely. The surface of the driven fusing roller will be damaged in a short period of time.
If the contact angle becomes smaller than the allowable range, the separation effect of the lower separation claw will be reduced, and the separation effect of the lower separation claw will not be sufficiently exerted.

On the other hand, in Japanese Utility Model Application Publication No. 52-101447, a support plate is rotatably supported on a frame that supports the shaft of the fixing roller, and a separation claw (separation claw) is provided on the side edge of the fixing roll of this support plate. A fixing device is disclosed. In this fixing device, there is little possibility that the distance between the center axis of rotation of the fixing roll and the center axis of rotation of the separation claw will change between the time of design and the time of assembly.
The contact angle of the separation claw is maintained at a predetermined value.

However, although the support plate can rotate away from the fuser roll, the downstream side of the support plate cannot move upward. Generally, there is a conveyance roller downstream of the support plate, so if a jam occurs between the conveyance roller and the support plate, it is difficult to remove the jam. Furthermore, inspection and repair of the separation claws is not easy.

<Purpose of the invention> The invention was made based on the above facts.
The purpose is to provide an improved toner image fixing device that can maintain the contact angle of the separation claw of the separation mechanism at a predetermined value, and also allows jam removal and inspection and repair of the separation claw to be performed extremely easily. be.

<Summary of the invention> In order to achieve the above object, the invention provides: a driven fixing roller that is rotationally driven in a predetermined direction, a driven fixing roller that is driven by the driven fixing roller, and a mechanism that corresponds to the driven fixing roller. a separation mechanism disposed as a separation mechanism; and an upper conveyance roller and a lower conveyance roller disposed downstream of the driven fixing roller and the driven fixing roller in the sheet member conveyance direction; The rollers are configured to be selectively brought into an operating state in which they are pressed against each other by a lower support mechanism, and a non-operating state in which the pressure contact is released, and the lower support mechanism is a pair of rotatably supported rollers. The shaft portion of the driven fixing roller is supported by a receiving portion formed to open upwardly at one end of each of the lower support members, and the other end of each of the lower support members includes a receiving portion that is formed to open upwardly. In a toner image fixing device configured such that a spring acts to urge the driven fixing roller upward through the receiving portion, the separation mechanism is attached to a support shaft portion that constitutes a rotation center axis of the driven fixing roller. The support member includes a rotatably mounted support member and a separation claw rotatably mounted on the support member so as to act on the circumferential surface of the driven fixing roller, and the support member rotates in the rotation center axis direction of the driven fixing roller. It has a pair of side walls arranged at an interval and a connecting wall extending between the pair of side walls, and the upper surface of the connecting wall is configured to cover the sheet fed out from the driven fixing roller and the driven fixing roller. A guide surface is defined for guiding the member to the nip portion of the upper conveyance roller and the lower conveyance roller, and a receiving recess that is open downward is formed at one end of the side wall portion of the supporting member, and the receiving recess is configured to The driven fixing roller is rotatably and removably received and supported by the support shaft portion of the driven fixing roller, and the other end of the side wall portion is formed with a downwardly open elongated hole receiving portion,
The elongated hole receiving portion is rotatably and detachably received and supported by the shaft portion of the lower conveyance roller, and movably along the longitudinal direction of the elongated hole receiving portion, and the driven fixing roller and the driven fixing roller When the fixing roller is in the non-operating state, the other end of the elongated hole receiving portion is positioned at a distance from the shaft portion of the lower conveyance roller, and the driven fixing roller and the driven fixing roller Provided is a toner image fixing device, characterized in that, when in operation, the elongated hole receiving portion is positioned such that the other end is in contact with the shaft portion of the lower conveyance roller. .

<Preferred Specific Example of the Invention> Hereinafter, a preferred specific example of the toner image fixing device constructed according to the present invention will be described with reference to the accompanying drawings.

In FIG. 1 showing the main parts of a toner image fixing device, the illustrated toner image fixing device includes a pair of fixing rollers that cooperate with each other, namely a driven fixing roller 2 and a driven fixing roller 4. The driven fixing roller 2 located above includes a hollow cylindrical body 6 made of a suitable metal material such as an aluminum-based alloy, and an electric heating element 8 such as a resistance heater disposed within the hollow cylindrical body 6. It consists of a hollow cylindrical body 6
A surface coating of Teflon (trade name) 10 is applied to the peripheral surface to effectively prevent the adhesion of toner particles.
is applied. Further, the driven fixing roller 4 located below is composed of a shaft member 12 and a hollow roller body 14 rotatably attached to the shaft member 12 via a bearing member (therefore, the shaft member 12
The portions projecting outward from both end surfaces of the roller body 14 constitute support shaft portions 12a and 12b of the driven fixing roller 4). The peripheral surface of this roller body 14 is coated with a surface coating 16 of silicone rubber.

In a specific example, the toner image fixing device having the above-mentioned configuration includes a lower support frame and an upper support frame attached to the lower support frame so as to be rotatable between an open position and a closed position, although not shown in the drawings. The present invention is applied to an electrostatic copying apparatus having a so-called shell-type support structure. The driven fixing roller 2 and the driven fixing roller 4 are supported as required, for example, as disclosed in Japanese Utility Model Application Publication No. 60-19050.
That is, the toner image fixing device includes an upper support member (not shown) that supports the driven fixing roller 2 and a lower support mechanism 18 that supports the driven fixing roller 4. The upper support member (not shown) has a pair of upper support members, and the upper support member on one side is pivotally connected to the rear surface of a vertical front substrate (not shown) of the lower support frame (not shown); The other upper support member is rotatably connected to the front surface of the vertical rear substrate (not shown) of the lower support frame, and a shaft portion (not shown) of the driven fixing roller 2 is connected between the pair of upper support members. is rotatably mounted. A transmission member (not shown) such as a gear is fixed to the rear shaft portion of the driven fixing roller 2 . The lower support mechanism 18 has a pair of lower support members 20a and 20b, and one of the lower support members 20a is connected to the vertical front substrate (not shown) of the lower support frame (not shown) via a pin member 22a. ) is rotatably mounted on the rear surface of the other lower support member 2.
0b is rotatably attached to the front surface of the vertical rear substrate (not shown) of the lower support frame via a pin member 22b. Lower support members 20a and 20b
Approximately semicircular receiving portions 24a and 24b formed to open upward are defined at one end, respectively, and one piece of the driven fixing roller 4 is provided in the receiving portion 24a of the lower support member 20a. The support shaft portion 12a is supported, and the other support shaft portion 12b of the driven fixing roller 4 is supported by the receiving portion 24b of the lower support member 20b. Further, one end side of coil springs 26a and 26b is connected to the other end portions of the lower support members 20a and 20b, respectively, and the other end side of the coil springs 26a and 26b is connected to a connection mounted on the vertical front board, respectively. It is connected to a member 28a and a connecting member 28b attached to the vertical rear board.

As it is structured as shown,
Substantially similar to that disclosed in the '19050 publication, a portion of the upper support frame (not shown) acts on the upper support (not shown) when the upper support frame is in the closed position. The driven fixing roller 2 is thus held in the position shown in FIG. 1 and shown in solid line in FIG. When the driven fixing roller 2 is in the above position, a transmission member (not shown) attached to the shaft of the driven fixing roller 2 is drivingly connected to a drive source (not shown) of the copying device, and the driven fixing roller 2 is connected to the drive source (not shown) of the copying device. The roller 2 moves in the direction of the arrow 30 (second
It is rotated in the direction shown in the figure. At this time, the pair of coil springs 26a and 26b act to bias the lower support members 20a and 20b in the counterclockwise direction in FIG. The roller 4 is pressed against the driven fixing roller 2,
It is held in the position shown in FIG. 1 and shown in solid line in FIG. Therefore, when the upper support frame (not shown) is in the closed position, the driven fixing roller 2 and the driven fixing roller 4 are maintained in a working state in which they are pressed against each other, and the roller body 14 of the driven fixing roller 4 arrow 3 due to the action of the driven fixing roller 2
It is driven in the direction shown by 2.

On the other hand, when the upper support frame (not shown) is rotated as required to bring it to the open position, the contact between the upper support frame and the upper support (not shown) is released, and the driven fixing roller 2 and The driven fixing roller 4 is held at the position shown by the two-dot chain line in FIG. 2 by the action of the coil springs 26a and 26b. In this state, the driven fixing roller 2 comes into contact with the driven fixing roller 4 due to its own weight, and the driven fixing roller 2 and the driven fixing roller 4 are held in a non-operating state in which the pressure contact between both rollers is released. In addition, the driven fixing roller 2
When is in the position shown by the two-dot chain line in Figure 2,
The drive connection between the transmission member (not shown) provided on the driven fixing roller 2 and the drive source is released.

Referring to FIG. 2 in conjunction with FIG. 1, arrow 3
A pair of conveyance rollers 36 and 38 for conveying the sheet member further downstream are disposed on the downstream side thereof when viewed in the sheet member conveyance direction indicated by 4 (FIG. 2) (in FIG. 1, (The conveyance roller 38 is omitted from the illustration). Lower conveyance roller 36 located on the lower side
A shaft member 40 (configuring the shaft portion of the lower conveyance roller 36) is rotatably mounted via a bearing member 41 between a vertical front substrate and a vertical rear substrate (none of which are shown) of the lower support frame. A plurality of them are arranged at intervals in the axial direction, and are rotationally driven in the direction shown by an arrow 42 by the action of the drive source (not shown).
Further, the upper conveying roller 38 located on the upper side is attached to a shaft member 44 rotatably mounted between a pair of upper support members (not shown) of the upper support body on which the driven fixing roller 2 is mounted. A plurality of rollers are provided corresponding to the conveyance rollers 36. The upper conveyance roller 38 is held at the position shown in FIG. 2 when the upper support frame is in the closed position, and cooperates with the lower conveyance roller 36 to convey the sheet member downstream, so that the upper support frame is When in the open position, it is positioned above the lower conveyance roller 36 at a distance.

In the specific example, a separation mechanism 46 is further provided in association with the driven fixing roller 4. The illustrated separation mechanism 46 includes a support member 48 and a support member 4.
8 and includes a separation claw 50 attached to support member 48.
is arranged between the driven fixing roller 4 and the lower conveyance roller 36. To explain further, the illustrated support member 4
8 is the width direction of the driven fixing roller 4, that is, the shaft member 1
A pair of side walls 52 spaced apart from each other in the axial direction of FIG.
a and 52b, and a pair of side wall portions 52a and 52b.
It has a connecting wall portion 54 extending in the width direction between them. Approximately semicircular receiving recesses 56 are provided at one end portions of the side wall portions 52a and 52b (in other words, the upstream end portions when viewed in the sheet member conveyance direction indicated by the arrow 34).
a and 56b are formed, and receiving recesses 56a and 5
6b is open downward. At one end side of the support member 48, as shown in FIG.
One end portions a and 52b are attached to the support shaft portions 12a and 12b of the driven fixing roller 4, one support shaft portion 12a is rotatably received in the receiving recess 56a of the side wall portion 52a, and the other support shaft portion 12b is rotatably received in the receiving recess 56b of the side wall 52b. In other words, the receiving recess 56a
is rotatably and detachably received and supported by the support shaft portion 12a, and the receiving recess 56b is rotatably and detachably received and supported by the support shaft portion 12b. In addition, side wall portions 52a and 52b
Elongated hole receiving portions 58a and 58b are formed at the other end (in other words, the downstream end when viewed in the sheet member conveying direction indicated by the arrow 34), and the elongated hole receiving portion 58a
and one end portion (the right end portion in FIG. 2) of 58b is open downward. Then, the support member 4
8, as shown in FIG.
is attached to the shaft portion 40 of the shaft member 40, and one end side of the shaft portion 40 (i.e., one end portion of the shaft member 40) can freely turn into the elongated hole receiving portion 58a of the side wall portion 52a and freely move along the elongated hole receiving portion 58a. The other end side of the shaft portion 40 (that is, the other end portion of the shaft member 40) is received in the elongated hole 58b of the side wall portion 52b so as to be freely pivotable and movable along the elongated hole receiving portion 58b. There is. In other words, the long hole receiving portion 58a is connected to the shaft portion 4 of the lower conveyance roller 36.
The elongated hole receiving portion 58b is rotatably and detachably received and supported at one end of the shaft portion 40 of the lower conveying roller 36 so as to be movable along the longitudinal direction of the elongated hole receiving portion 58b. It is received and supported so as to be rotatable, detachable, and movable along the longitudinal direction of the elongated hole receiving portion 58b. In the specific example, as shown in FIG. 1, bearing members 41 are mounted on both ends of the shaft member 40 and received therein. The support member 48 mounted in this way is attached to the connecting wall portion 5, as can be understood from FIGS. 1 and 2.
The upper surface of 4 defines a guide surface for guiding the sheet member to the nip portion of the lower conveying roller 36 and the upper conveying roller 38. Further, a support shaft 60 extending substantially parallel to the shaft member 12 of the driven fixing roller 4 is fixed between the side wall portions 52a and 52b of the support member 48 described above, and a support shaft 60 is provided with an interval in the axial direction. A plurality of separation claws 50 (four in the specific example) are rotatably attached to the separation claws 50 . The illustrated separation claw 50 has a substantially triangular shape, and one corner thereof is rotatably attached to the support shaft 60. Each separation claw 50 and support shaft 6
Although not shown, a spring member such as a torsion coil spring is interposed between each of the separation claws 50 in the clockwise direction in FIG. 2 by the action of the spring member. One corner close to the driven fixing roller 4 is elastically pressed against the circumferential surface of the driven fixing roller 4 . Note that the sheet member sent out from the driven fixing roller 2 and the driven fixing roller 4 is separated from the connecting wall portion 5 of the support member 48 by the action of the separating claw 50.
4, it is necessary to make one corner of the separation claw 50 that acts on the driven fixing roller 4 project upward beyond the top surface of the connecting wall 54.
In a specific example, the connecting wall portion 54 of the support member 48
A plurality of openings 62 are formed at intervals in the width direction of the driven fixing roller 4, and the separating claws 50 are arranged within predetermined openings 62.

In the specific example, the connecting wall portion 5 of the support member 48
Although the upper surface of 4 defines a guide, if a separate guide plate is provided between the driven fixing roller 4 and the lower conveyance roller 36, the connecting wall portion 54 may be omitted and a pair of supporting walls may be used. be able to. In such a case, as described above, one end of the pair of support walls is rotatably attached to the support shafts 12a and 12b of the driven fixing roller 4, and the other end thereof is attached to the shaft of the lower conveyance roller 36. 40 so as to be rotatable and movable over a predetermined range, and one end of the pair of support walls may be rotatably attached to the support shaft portions 12a and 12b of the driven fixing roller 4. The other end of the lower conveyor roller 3
It may be made to abut on a part of the lower support frame (not shown) without being attached to the shaft portion 40 of No. 6,
Further, one end of the pair of support walls is connected to the driven fixing roller 4.
It may be fixed to the support shaft portions 12a and 12b.

Although not shown, an upper separation mechanism, which is known per se, is also provided in association with the driven fixing roller 2.

Next, the effects of the toner image fixing device having the above-described configuration will be explained.

When the driven fixing roller 2 and the driven fixing roller 4 are in the operating state shown by solid lines in FIG.
When the sheet member having the toner image is conveyed in the direction shown by the arrow 34, the sheet member is conveyed between the driven fixing roller 2 and the driven fixing roller 4, and the toner image is transferred onto the sheet member while passing between both rollers. will be established. The sheet member with the toner image fixed on it is
It is sent out through between both rollers, guided to the upper surface of the connecting wall portion 54 of the support member 48 by the action of the separating claw 50, and guided by the upper surface of the connecting wall portion 54 to the lower conveying roller 36 and the upper conveying roller 38. It is transported towards the nip site. When the leading edge of the sheet member is sent out from the driven fixing roller 2 and the driven fixing roller 4, one corner of each separation claw 50 is moved around the driven fixing roller 4 by the action of a spring member (not shown). Since the sheet member is in elastic pressure contact with the surface, even if the sheet member tends to wrap around the circumferential surface of the driven fixing roller 4, the above-mentioned one corner of the separation claw 50 acts on the tip end of the sheet member and the driven fixing roller 4, thereby preventing the sheet member from being wrapped around the driven fixing roller 4.

In the toner image fixing device described above, when the upper support frame of the copying device is placed in the open position, the driven fixing roller 2 and the driven fixing roller 4 are moved by the action of the coil springs 26a and 26b, as described above. It is located at the position indicated by the two-dot chain line in FIG. At this time, as understood from Figure 2,
Due to the action of the coil springs 26a and 26b, the lower support members 20a and 20b are rotated somewhat counterclockwise in FIG. 2, and the driven fixing roller 4 is moved upward. The support member 48 of the separation mechanism 46 is then moved to the left in FIG. Therefore, when the upper support frame (not shown) is in the closed position, the shaft portion 40 of the lower conveyance roller 36 is formed on the side walls 52a and 52b of the support member 48, as shown by solid lines in FIG. The support members 48 are located at the other ends of the elongated hole receiving portions 58a and 58b, and are reliably prevented from coming off, but when the upper support frame is placed in the open position, as shown by the two-dot chain line in FIG. , the shaft portion 40 of the lower conveyance roller 36 is connected to the elongated hole receiving portion 5 of the side wall portions 52a and 52b.
8a and 58b,
Thus, by lifting the support member 48 upward in such a state, the support member 48 can be removed as required, and the separation claw 50 can be inspected.
Repairs can be easily performed. In other words, when the driven fixing roller 2 and the driven fixing roller 4 are in the non-operating state (the two-dot chain line position in FIG. 2),
The other ends (left end in FIG. 2) of the elongated hole receiving parts 58a and 58b are positioned at a distance from the shaft part 40 of the lower conveyance roller 36, and the driven fixing roller 2 and the driven fixing roller 4 are in the operating state ( When in the solid line position in FIG. 2), the elongated hole receiving parts 58a and 58b are
The other end is positioned in contact with the shaft portion 40 of the lower conveyance roller 36 . Further, as is easily understood from the above description, even when the driven fixing roller 4 is moved upward, one end side of the support member 48 is rotatably connected to the support shaft portions 12a and 12b of the driven fixing roller 4. Therefore, the axes of the support shaft portions 12a and 12b of the driven fixing roller 4 (as is easily understood, these axes constitute the rotation center axis of the driven fixing roller 4) and the support shaft fixed to the support member 48. 60 (as is easily understood, this axis constitutes the pivot axis of each separation claw 50) does not change, and the contact angle of each separation claw 50 (the distance between the separation claw 50 and the driven fixing roller 4
The angle between the common tangent at the contact point and the straight line connecting the contact point and the axis of the support shaft 60) and the contact pressure are always maintained at predetermined values, thus preventing the separation claw 50 from digging in as the driven fixing roller 4 moves. is also prevented. Furthermore, in relation to the above, even if the state of pressure contact between the driven fixing roller 2 and the driven fixing roller 4 changes due to variations in the hardness of the driven fixing roller 4, the contact angle of the separating claw 50 does not substantially change. Thus, the inconveniences associated with fluctuations in the contact angle, which conventionally existed, are reliably eliminated.

Although a specific example of a toner image fixing device configured according to the present invention has been described above, the present invention is not limited to this specific example, and various modifications and variations can be made without departing from the scope of the present invention. Modification is possible.

For example, in the specific example, the driven fixing roller 2 and the driven fixing roller 4 are movable, which is suitable for a shell-type copying machine.
Without being limited thereto, the driven fixing roller 2
The present invention can also be applied to a configuration in which the driven fixing roller 4 is moved relative to the driven fixing roller 2 so as to be selectively brought into an operating state or a non-operating state.

Further, in a specific example, a predetermined separation mechanism 46
are arranged corresponding to the driven fixing roller 4,
Without being limited to this, the driven fixing roller 2
Alternatively, they may be provided corresponding to both fixing rollers 2 and 4.

<Effects of the invention> According to the toner image fixing device improved according to the invention, the following effects are achieved.

(1) The separation mechanism includes a support member that is rotatably attached to a support shaft that constitutes the rotation center axis of the driven fixing roller, and a separation claw that is rotatably attached to the support member so as to act on the peripheral surface of the driven fixer roller. It is configured to include. That is, the separation claw is rotatably attached to a support member that is rotatably attached to the support shaft.

As a result, the distance between the rotational center axis of the driven fixing roller and the rotational center axis of the separation claw does not change between the design time and the assembly time, and the contact angle of the separation claw is maintained at a predetermined value.

(2) A receiving recess that is open downward is formed at one end of the side wall of the support member, and the receiving recess is rotatably and removably received and supported by the support shaft of the driven fixing roller, and the side wall Each of the other ends is formed with a downwardly open elongated hole receiving portion, and the elongated hole receiving portion is rotatably attached to and detachable from the shaft portion of the lower conveyance roller, and is movable along the longitudinal direction of the elongated hole receiving portion. be freely accepted and supported, and
When the driven fixing roller and the driven fixing roller are in a non-operating state, the elongated hole receiving portion is configured such that the other end thereof is positioned at a distance from the shaft portion of the lower conveyance roller.

As a result, when the driven fixing roller and the driven fixing roller are in the non-operating state, the supporting member can be separated from the supporting shaft of the driven fixing roller and the shaft of the lower conveyance roller, so that the lower part of the supporting member is large. This makes jam disposal much easier than in the past. Furthermore, since the separating claw is attached to the detached support member, the separating claw can be inspected and repaired very easily.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a main part of a specific example of a toner image fixing device constructed according to the present invention. 2 is a side view showing essential parts of the toner image fixing device shown in FIG. 1; FIG. 2... Driven fixing roller, 4... Driven fixing roller, 12... Shaft member, 18... Lower support mechanism, 46
... separation mechanism, 48 ... support member, 50 ... separation claw, 60 ... support shaft.

Claims (1)

[Claims for Utility Model Registration] A driven fixing roller that is rotationally driven in a predetermined direction, a driven fixing roller that is driven by the driven fixing roller, and a separation mechanism disposed corresponding to the driven fixing roller; The driven fixing roller and the driven fixing roller are provided with an upper conveying roller and a lower conveying roller that are arranged downstream of the driven fixing roller in the sheet member conveying direction, and the driven fixing roller and the driven fixing roller are mutually supported by a lower support mechanism. The lower support mechanism includes a pair of rotatably supported lower support members, and the lower support mechanism is configured to be selectively brought into an operative state in which the pressure contact is made and a non-operation state in which the pressure contact is released. The shaft portion of the driven fixing roller is supported by a receiving portion formed to open upward at one end of each of the members, and a spring acts on the other end of each of the lower supporting members to support the receiving portion. In the toner image fixing device configured to urge the driven fixing roller upward through the toner image fixing device, the separation mechanism includes a support member rotatably mounted on a support shaft portion that constitutes a rotation center axis of the driven fixation roller. The supporting member includes a separating claw rotatably attached to the supporting member so as to act on the circumferential surface of the driven fixing roller, and the supporting member includes a pair of separating claws spaced apart from each other in the rotation center axis direction of the driven fixing roller. It has a side wall portion and a connecting wall portion extending between the pair of side wall portions, and the upper surface of the connecting wall portion connects the sheet member sent out from the driven fixing roller and the driven fixing roller to the upper conveying roller and the lower conveying roller. A guide surface leading to the nip portion of the conveyance roller is defined, and receiving recesses each opening downward are formed at one end of the side wall portion of the support member, and the receiving recesses are connected to the support shaft portion of the driven fixing roller. The side wall portion is rotatably and detachably received and supported, and the other end of the side wall portion is formed with a downwardly open elongated hole receiving portion,
The elongated hole receiving portion is rotatably and detachably received and supported by the shaft portion of the lower conveyance roller, and movably along the longitudinal direction of the elongated hole receiving portion, and the driven fixing roller and the driven fixing roller When the fixing roller is in the non-operating state, the other end of the elongated hole receiving portion is positioned at a distance from the shaft portion of the lower conveyance roller, and the driven fixing roller and the driven fixing roller A toner image fixing device characterized in that, when in operation, the other end of the elongated hole receiving portion is positioned so as to abut against the shaft portion of the lower conveyance roller.