JP3636275B2 - Belt position detection device for belt conveyor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a belt position detecting device used for meandering control in a belt conveying device in which a belt is circulated, and more particularly to a so-called belt nip type fixing device used in an image forming apparatus such as an electrophotographic copying machine. The present invention relates to an improvement in a belt position detection device for a belt conveying device that is effective.
[0002]
[Prior art]
Conventionally, as this type of belt conveying device, for example, there is a belt nip type fixing device (fixing device that can be used for color fixing with high speed and high image quality) that is disposed in pressure contact with a heat fixing roll.
This is because a plurality of support roll groups are arranged in parallel, an endless heat-resistant belt is stretched over these support roll groups, and the belt is circulated and conveyed, whereby unfixed toner is provided between the heat fixing roll and the belt. A sheet carrying an image or the like is conveyed (for example, see Japanese Patent Laid-Open No. 5-150678).
[0003]
By the way, in the belt nip type fixing device using this kind of endless belt, the deviation (meandering) of the belt is an important technical problem. Usually, one of the supporting rolls on which the belt is stretched is used. A technique is adopted in which a tiltable steering roll is used, and the belt is offset by adjusting the alignment of the steering roll.
In order to perform such belt misalignment correction, it is indispensable to install a belt position detecting device at a position facing the end position of the belt in order to detect the belt misalignment.
[0004]
Conventionally, as this type of belt position detecting device, for example, one using an optical sensor can be considered, but it is not preferable in terms of reliability in an environment where the surroundings are at a high temperature like a fixing device, and polyimide resin or the like. In the embodiment using the resin belt, since it is difficult in production to uniformly coat the light-shielding coat layer up to the belt end portion, for example, as shown in FIG. Due to variations in the end position of the layer 102, there is a concern that the end position of the belt 100 cannot be reliably detected by the optical sensor 110. Even if the end position can be detected, chattering may occur due to processing accuracy of the end of the belt 100. It is necessary to control the deviation of the belt 100, and the deviation control of the belt 100 becomes very troublesome. In FIG. 17, reference numeral 103 denotes a heat fixing roll.
[0005]
For this reason, as a means for solving the problems of this type of conventional belt position detection device, for example, a mechanical microswitch as described in JP-A-5-341673 and JP-A-8-22213 Those using 120 are disclosed.
For example, as shown in FIG. 18, a wire actuator (swing detection arm) 121 made of a single wire that touches the end of the belt 100 and swings in accordance with the movement of the end position of the belt 100 is provided. And the position of the belt 100 is detected based on the swing position of the wire actuator 121.
According to this type, the end position of the belt 100 can be reliably detected by the wire actuator 121, and the swing range of the wire actuator 121 required for the on / off operation of the microswitch 120 can be arbitrarily set. Thus, since the sensitivity can be adjusted so as not to become sensitive, unlike the case of the optical sensor 110, it is preferable in that the deviation control of the belt 100 is simplified.
[0006]
[Problems to be solved by the invention]
However, in this type of microswitch-type belt position detecting device, as shown in FIG. 18, the wire actuator 121 always slides in contact with the end of the belt 100, so that the end of the belt 100 is reached. When a coat layer (for example, an elastic layer and a release layer) is coated, there is a concern that the coat layer 100a at the end of the belt 100 may be damaged or peeled off. Further, in such a state, there is a concern that the edge of the belt 100 directly contacts the heat fixing roll 103 and the coat layer 103a on the surface of the heat fixing roll 103 may be scratched or peeled off.
For this reason, conventionally, in order to prevent the coating layer coated on the belt 100 from being scratched or peeled off, it is necessary to mask the belt base end portion so that the coating layer is not provided on the belt 100 end portion. This leads to a technical problem that the manufacturing cost of the belt 100 increases accordingly.
[0007]
In addition, as shown in FIG. 19, a hard roller (in other words, a hard roller) 122 made of hard plastic is provided at the tip of the leaf spring 123 to reduce the wear of the belt 100 end and the contact portion of the hard roller 122. Have already been provided (see, for example, JP-A-5-341673).
However, although this type is effective for a metal belt having high rigidity and high frictional force, for example, a metallic belt is used as a belt of a belt conveyance device (for example, a heat fixing device) that circulates and conveys the belt. When using, there is a big problem in the safety of the metal belt wear powder and the belt end when removing the jam.
On the other hand, if it is used for a low-rigidity belt such as polyimide resin with low rigidity, it is necessary to reduce the contact pressure, and the frictional force at the belt end is low. ) Does not provide stable rotation, and eventually slides with the hard roller in contact with the belt end, it is still insufficient to effectively avoid scratching or peeling off the belt end.
[0008]
The present invention has been made to solve the above technical problem, and reliably damages the belt end portion due to the contact between the swing detection arm and the belt end portion without affecting the type of the belt. It is an object of the present invention to provide a belt position detecting device for a belt conveying device that can be prevented.
[0009]
[Means for Solving the Problems]
  That is, according to the present invention, as shown in FIG. 1, a plurality of roll groups 2 including at least a tiltable steering roll 2 a for adjusting meandering are arranged in parallel, and an endless belt 1 is attached to these roll groups 2. A belt position detection device 3 used for a belt conveyance device that circulates and conveys the belt 1, and swings according to the movement of the end position of the belt 1 to detect the position of the belt 1.Wire shapeAn elastic roller 5 having an oscillation layer 4 having at least a surface portion is provided at a position corresponding to a contact portion with the belt 1 end of the oscillation detection arm 4.Using the swing detection arm itself as the axisIt is characterized by being mounted rotatably.
  1 illustrates a belt conveying device in a belt nip type fixing device. In FIG. 1, reference numeral 7 denotes a heat fixing roll, and 8 denotes a fixing nip region by sandwiching the belt 1 with the heat fixing roll 7. Assist members 9 and 9 are recording materials such as paper.
[0010]
In such technical means,Belt position detector 3Is widely applied to belt conveyors, but in particular, it is easy to adjust the sensitivity by arbitrarily setting the point of high reliability in a high-temperature environment and the swing range of the swing detection arm 4 From a point of view, this is effective for a belt conveying device used in a belt nip type fixing device.
In addition, the layout of the belt position detecting device 3 of the present application may be installed at one end of the belt 1 of the belt conveying device, or may be installed opposite to both end portions of the belt 1. Also good.
Furthermore, the belt 1 which is the subject of the present application can be applied to any belt 1 (metal belt, rubber or resin belt), and in particular, low rigidity such as polyimide resin having low rigidity.Belt 1This is effective for the aspect in which the belt substrate 1a is covered with the coat layer 1b up to the end.
[0011]
Further, the swing range of the swing detection arm 4 may be set in consideration of the meandering allowable width necessary for performing the meandering control of the belt 1, and the ON contact and the OFF contact of the belt position detection device 3 are set. What is necessary is just to set suitably in the rocking | fluctuation position of this rocking | fluctuation detection arm 4.
[0012]
Further, the layout of the belt position detecting device 3 may be arbitrarily set if it is installed corresponding to the end portion of the belt 1, but the end of the belt 1 region where the relative position changes according to the tilting of the steering roll 2a. In the case where the swing detection arm 4 is arranged facing the portion, it is necessary to set the length dimension of the elastic roller 5 to be larger than the relative movement amount of the belt 1.
[0013]
  Furthermore, when the elastic roller 5 is attached to the swing detection arm 4, the elastic roller 5 is not moved unnecessarily.Preferably mounted in a positioned stateFor example, the lower position of the elastic roller 5 is positioned by the positioning member 6 fixed to the swing detection arm 4.An embodiment is mentioned.
  Here, the positioning member 6 may be appropriately selected from an abacus bead, a sphere, an ellipsoid, and the like, and the positioning member 6 may be mounted on the positioning member 6 with the swing detection arm 4. A through-hole having the same diameter as the above-described diameter may be provided, and the rocking detection arm 4 may be passed through the through-hole, and the positioning member 6 may be fixed with an adhesive or the like at a predetermined position.
[0014]
Further, the elastic roller 5 may be one in which the elastic layer 5a is formed on the surface of the roller base material 5b, or may be one in which the whole is constituted by an elastic body.
here,Roller substrate 5bAs an aspect of forming the elastic layer 5a on the surface, for example, an aspect in which the surface of the roller base 5b is coated with an elastic material in a layered manner, an elastic tube is fitted to the roller base 5b, orRoller substrate 5bThe aspect which comprises itself with an elastic tube, or the aspect which coat | covers the roller base material 5b with a heat-shrinkable tube is mentioned.
On the other hand, as an aspect in which the elastic roller 5 is constituted by an elastic body, an aspect in which the roller base material 5b itself is formed of an elastic material, an aspect in which the roller base material 5b itself is constituted by an elastic tube, and the roller base material 5b itself is a heat-shrinkable tube. The thing of the aspect comprised by is mentioned. In this case, the longRoller substrate 5bIf the manufacturing method of covering the heat shrinkable tube in advance or cutting the length of each elastic roller 5 after shrinking the long heat shrinkable tube is adopted, the manufacturing process of the elastic roller 5 is simplified. It is preferable in that it can be made.
[0015]
Also,Elastic roller 5In the embodiment in which the elastic roller 5 is formed only from the viewpoint of protecting the shape of the elastic roller 5, it is preferable to cover both ends of the elastic roller 5 with protective members fixed to the swing detection arm 4. .
[0016]
Next, the operation of the technical means described above will be described.
In FIG. 1, the swing detection arm 4 of the belt position detection device 3 swings according to the movement of the end position of the belt 1 and detects the belt position.
At this time, the elastic roller 5 rotatably attached to the swing detection arm 4 is in contact with the end portion of the belt 1.
In such a state, even if the contact pressure or contact area of the swing detection arm 4 to the end of the belt 1 is small, or a release material (silicon oil or the like) between the elastic roller 5 and the end of the belt 1 Is applied, the frictional force between the elastic roller 5 and the end of the belt 1 increases due to the presence of the elastic layer 5a of the elastic roller 5, and the elastic roller 5 rotates stably and the end of the belt 1 Follows the rotation of the elastic roller 5.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
2 and 3 show an embodiment of a belt nip type fixing device to which the present invention is applied.
In the figure, the fixing device is placed on a heat fixing roll 20 having a built-in heater 21 and a plurality of support rolls 31 to 33 so as to be pressed against the heat fixing roll 20 in a predetermined fixing nip region. A belt module 30 having an endless belt 34 is provided.
[0018]
In the present embodiment, the heat fixing roll 20 has an elastic layer, and an oil supply for supplying oil as a toner release agent, for example, to the upstream side of the fixing nip region around the heat fixing roll 20. A device 22 is provided, and a web cleaning device 23 for cleaning the transfer toner on the heat fixing roll 20 is provided downstream of the fixing nip region.
[0019]
On the other hand, as the endless belt 34 of the belt module 30, for example, a belt base material 34a made of a low-rigid polyimide resin is covered with a coating layer 34b made of an elastic layer and a release layer (see FIG. 6).
The support roll 31 is pressed against the heat fixing roll 20 at the downstream end of the fixing nip region of the endless belt 34, and the sheet 15 is obtained by elastically deforming the heat fixing roll 20 corresponding to the support roll 31. Self-stripping function is ensured.
Further, an assist pad 35 is disposed inside the front end of the support roll 31 in the fixing nip region of the endless belt 34, and the endless belt 34 is sandwiched between the heat fixing roll 20, so that the self-stripping portion is located. The speed-up of the endless belt 34 is suppressed and image disturbance is suppressed.
In the present embodiment, a heater (not shown) is built in the support roll 32 located on the front side of the fixing nip region of the endless belt 34, and the endless belt 34 heading toward the fixing nip region is preheated. It is supposed to be.
[0020]
Further, in the present embodiment, the support roll 33 is configured as a tiltable steering roll, and a belt position detecting device 40 is provided at the end of the endless belt 34 located between the steering roll 33 and the support roll 32. And a detection signal from the belt position detection device 40 is input to the controller 50. The control signal from the controller 50 controls the alignment adjustment device 60 to tilt the steering roll 33 to a predetermined position. Yes.
In the present embodiment, the alignment adjusting device 60 is connected to a steering motor 61 that is rotatable in a predetermined direction and a shaft 61a of the steering motor 61, and is connected to the shaft 61a of the steering motor 61. An eccentric cam 62 in which an eccentric locking portion 62a is formed at a portion eccentric to the eccentric cam 62, and a link that restrains the eccentric locking portion 62a of the eccentric cam 62 and a rotation shaft support portion (not shown) of the steering roll 33. The mechanism 64 is provided.
[0021]
In particular, in the present embodiment, the belt position detecting device 40 is of a mechanical microswitch type as shown in FIG. 4, and has a swingable wire actuator 45 that functions as a switch contact piece with respect to the switch body 41. doing. In FIG. 4, reference numeral 42 indicates a connection terminal from the switch body 41.
As shown in FIGS. 5 (a) and 5 (b), this wire actuator 45 is made of, for example, a stainless steel outer diameter d (φ0.6) as used in model number 014-0028N manufactured by Hirose Cherry Precision Co., Ltd. A circular wire is used, and a base end is pivotably supported on a swing fulcrum 451 of the switch body 41, and a tip is bent as a hook-shaped bent portion 452.
The swinging direction of the wire actuator 45 is set in a direction corresponding to the meandering direction of the endless belt 34, and the swinging range is within the allowable meandering range of the endless belt 34 and the ON contact and the OFF contact in the switch body 41. And are set to switch.
[0022]
An elastic roller 46 is rotatably attached to the wire actuator 45.
Here, the elastic roller 46 opens a wire insertion hole 462 having a hole diameter slightly larger than the outer diameter d of the wire actuator 45 at the center of the cylindrical roller base 461, while the side periphery of the roller base 461. The surface is covered with an elastic layer 463, and the wire actuator 45 is inserted through the wire insertion hole 462.
In particular, in the present embodiment, since the end position of the endless belt 34 corresponding to the belt position detecting device 40 is displaced by tilting the steering roll 33, the length dimension h of the elastic roller 46 is set to the steering roll. The elastic roller 46 and the end position of the endless belt 34 are selected so that the end position of the endless belt 34 is displaced even when the end position of the endless belt 34 is displaced due to the tilting of 33.
[0023]
Further, for example, an abacus bead-like positioning bead 47 is attached to a position corresponding to the lower restriction position of the elastic roller 46 of the wire actuator 45.
The positioning rod 47 has a through hole 471 having a hole diameter equivalent to that of the wire actuator 45 at the center, and the wire actuator 45 is passed through the through hole 471 and fixed with an adhesive or the like.
[0024]
Next, the operation of the belt position detection device 40 according to the present embodiment will be described.
In this embodiment, as shown in FIG. 6, the elastic roller 46 of the wire actuator 45 is disposed in contact with the end of the endless belt 34. When the endless belt 34 meanders, the wire actuator 45 follows the meandering. Swings.
When the swinging amount of the wire actuator 45 reaches a predetermined amount, the ON contact or OFF contact of the switch body 41 is closed and a predetermined detection signal is sent to the controller 50.
Then, the controller 50 controls the alignment adjustment device 60, tilts the steering roll 33 as appropriate, and controls the meandering of the endless belt 34.
[0025]
Looking at the behavior of the belt position detecting device 40, the wire actuator 45 has a very small contact pressure with respect to the end of the endless belt 34 (in this example, made by Hirose Cherry Precision Co., Ltd., light torque operation). And the silicon oil 70 (see FIG. 8) as a release material from the heat fixing roll 20 is indirectly applied to the surface of the endless belt 34. It was confirmed that the elastic roller 46 in contact with the end portion of the endless belt 34 was stably rotated even under the condition of application, and the end portion of the endless belt 34 was driven by the elastic roller 46.
[0026]
For this reason, the situation where the elastic roller 46 does not rotate and slides on the end of the endless belt 34 does not occur.34bThere were no signs of damage or peeling.
Further, since the contact pressure of the wire actuator 45 to the end of the endless belt 34 is very small, the end of the endless belt 34 is not turned up by contact without unnecessarily increasing the tension of the endless belt 34. I couldn't.
Furthermore, in the present embodiment, the end of the endless belt 34 is covered with the coating layer 34b, and the end of the endless belt 34 is not damaged. The situation where the end of the belt 34 directly contacts does not occur, and the surface of the heat fixing roll 20 is not damaged.
[0027]
Further, in the present embodiment, as shown in FIG. 6, since the elastic roller 46 is disposed in contact with the end of the endless belt 34, depending on the axial position of the wire actuator 45, FIG. ) As shown in (b), the elastic roller 46 comes into contact with the end of the endless belt 34 in an inclined state.
However, even if the elastic roller 46 is inclined with respect to the end of the endless belt 34, the end of the endless belt 34 is not damaged by the presence of the elastic layer 463 (see FIG. 6) of the elastic roller 46. .
Accordingly, the contact surface of the elastic roller 46 does not necessarily have to be arranged in parallel with the end portion of the endless belt 34, and accordingly, the degree of freedom of the attachment position of the belt position detection device 40 increases.
[0028]
Further, in the present embodiment, when the paper 15 passes through the fixing device, the silicon oil 70 as a release material on the surface of the heat fixing roll 20 is almost impregnated in the paper 15, but the width of the endless belt 34 is usually set to the paper 15. Since it is wider than the width, as shown in FIG. 8, the silicon oil 70 on the heat fixing roll 20 is indirectly applied to the end surface of the endless belt 34 and always maintained.
At this time, the silicone oil 70 adhering from the end of the endless belt 34 is temporarily stored in the positioning rod 47 positioned below the elastic roller 46, and continuously, the rotating shaft portion (wire actuator 45 of the elastic roller 46). And the wire insertion hole 462 are equivalent to the engagement portion).
For this reason, wear of the rotating shaft portion of the elastic roller 46 is prevented, and the rotation of the elastic roller 46 is stably maintained.
[0029]
Next, the manufacturing method of the wire actuator peripheral part which concerns on this Embodiment is demonstrated based on FIG. 9, FIG.
In FIG. 9, first, the roller base 461 of the elastic roller 46 and the positioning rod 47 are assembled to the wire actuator 45, while the heat shrinkable tube 464 having an inner diameter larger than that of the roller base 461 is used for forming the elastic layer of the elastic roller 46. And the surface of the roller base material 461 may be covered with the heat shrinkable tube 464 by performing a heating process using hot air in a state where the heat shrinkable tube 464 is loosely fitted around the roller base material 461. .
Also, as shown in FIG. 10, a heat shrinkable tube 466 is coated around a long roller base 465, and then cut into predetermined dimensions to cut elastic rollers 46 (end size roller base 461, heat shrinkable tube). The elastic layer 463) may be formed by 464, and on the other hand, the positioning rod 47 may be assembled to the wire actuator 45 in advance, and the elastic roller 46 may be assembled thereto.
According to the latter manufacturing method, since the coating process with the heat-shrinkable tube 464 can be collectively performed on the roller base material 465, the manufacturing process is further simplified as compared with the former manufacturing method which is performed individually.
[0030]
Further, according to the present embodiment, the wire actuator 45 is supported so as to be able to swing freely with the swinging fulcrum 451 as a fulcrum. However, the present invention is not limited to this. For example, as shown in FIG. A bent portion 453 is provided in a part of the wire actuator 45 supported by the swing fulcrum 451, and the mounting surface of the switch body 41 of the belt position detecting device 40 is disposed in parallel with the tangential direction of the endless belt 34, and is elastic. The contact surface of the roller 46 may be always parallel to the end of the endless belt 34.
In this case, it is preferable in that the elastic roller 46 hardly comes into contact with the surface coat layer 34b of the endless belt 34, and the abrasion of the surface coat layer 34b by the elastic roller 46 does not occur at all.
[0031]
Furthermore, in the present embodiment, the abacus bead-shaped positioning bead 47 is used. However, the present invention is not limited to this. For example, as shown in FIG. There is no problem.
[0032]
Further, the elastic roller 46 is not limited to the one shown in the embodiment, and may be configured in a modified form as shown in FIGS.
13 shows an embodiment in which the length h2 of the heat shrinkable tube 464 (which constitutes the elastic layer 463) is shorter than the length h1 of the roller base 461, and FIG. 14 shows the length of the roller base 461. In this embodiment, the length h2 of the heat shrinkable tube 464 (for forming the elastic layer 463) is set to be longer than the size h1, and the heat shrinkable tube 464 is hardly pulled out by the both-ends reduced diameter portions 467 of the heat shrinkable tube 464.
Further, FIG. 15 shows that the roller base 461 has a bobbin shape, large diameter portions 468 are formed at both ends of the roller base 461, and the heat shrinkable tube 464 is formed on the peripheral surface of the roller base 461 sandwiched between the large diameter portions 468. An embodiment in which the heat-shrinkable tube 464 is difficult to be removed by covering (for the elastic layer 463 configuration) is shown.
Further, FIG. 16 shows an aspect in which the elastic roller 46 is configured by only the heat shrinkable tube 464 without using the hard roller base material 461.
In such an embodiment, since the hard roller base material 461 is not used, the shape collapse at both ends of the elastic roller 46 is likely to occur.
For this reason, for example, it is preferable to fix the washer 48 to the wire actuator 45 corresponding to both ends of the elastic roller 46 to avoid the shape collapse of both ends of the elastic roller 46.
[0033]
In the embodiment and the modification, the elastic roller 46 is exemplified by using the heat-shrinkable tube 464, but it is needless to say that the elastic roller 46 is not limited to this.
[0034]
【The invention's effect】
  As described above, according to the present invention, in the mechanical microswitch type belt position detecting device, the belt swings in accordance with the movement of the belt end.Wire shapeSwing detection armUsing itself as an axisSince the elastic roller is rotatably mounted and this elastic roller is arranged in contact with the belt end, even if the contact pressure to the belt end of the oscillation detection arm or the contact area is small, the elastic roller Even if a release material (silicone oil, etc.) is applied between the belt and the belt end, the elastic layer of the elastic roller increases the frictional force between the elastic roller and the belt end to stabilize the elastic roller. And the belt end can be driven by the rotation of the elastic roller.
  For this reason, even with a weak contact pressure, the swing detection arm does not slide with respect to the belt end, and damage to the belt end can be reliably prevented.
[0035]
Therefore, even when a low-rigidity belt is used, the belt can be prevented from being turned up due to contact without increasing the belt tension, and the reliability of the belt can be ensured over a long period of time.
Furthermore, even if the coating layer is covered up to the belt base end, it is possible to prevent the belt end from being scratched or peeled off due to the presence of the elastic roller. This eliminates the troublesome manufacturing process of not providing the belt at the end portion of the belt, thereby reducing the belt manufacturing cost.
In addition, the belt position detection device according to the present invention can be simply manufactured by diverting the existing belt position detection device because it only needs to add an elastic roller to the existing microswitch system. .
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing an outline of a belt position detection device of a belt conveyance device to which the present invention is applied.
FIG. 2 is an explanatory diagram showing an outline of a belt nip type fixing device to which the present invention is applied.
3 is an arrow view seen from the direction III in FIG. 2. FIG.
FIG. 4 is an explanatory diagram showing an outline of a belt position detection device used in the embodiment.
5A is an explanatory view showing a configuration of a wire actuator peripheral portion (V portion in FIG. 4) of the belt position detecting device of FIG. 4, and FIG. 5B is a cross-sectional explanatory view thereof.
6 is a detailed cross-sectional view of the IV part of FIG. 3. FIG.
FIGS. 7A and 7B are explanatory views showing a mounting posture of the belt position detecting device according to the embodiment. FIGS.
FIG. 8 is an explanatory diagram showing the influence of silicon oil on the belt on the belt position detecting device according to the embodiment.
FIG. 9 is an explanatory view showing an example of a method for manufacturing the peripheral portion of the wire actuator of the belt position detection device according to the embodiment.
FIG. 10 is an explanatory view showing another example of the method for manufacturing the peripheral portion of the wire actuator of the belt position detecting device according to the embodiment.
FIG. 11 is an explanatory view showing a modified form of the support structure of the wire actuator according to the embodiment.
FIG. 12 is an explanatory view showing a modification of the elastic roller positioning structure according to the embodiment.
13A is an explanatory view showing another modified form of the elastic roller according to the embodiment, and FIG. 13B is a cross-sectional explanatory view thereof.
14A is an explanatory view showing still another modified form of the elastic roller according to the embodiment, and FIG. 14B is a cross-sectional explanatory view thereof.
FIG. 15A is an explanatory view showing still another modified form of the elastic roller according to the embodiment, and FIG. 15B is a cross-sectional explanatory view thereof.
FIG. 16A is an explanatory view showing still another modified form of the elastic roller according to the embodiment, and FIG. 16B is a cross-sectional explanatory view thereof.
FIG. 17 is an explanatory diagram showing an example of a belt position detection device used in a conventional belt nip type fixing device.
FIG. 18 is an explanatory view showing another example of a belt position detecting device used in a conventional belt nip type fixing device.
FIG. 19 is an explanatory view showing still another example of a belt position detecting device used in a conventional belt nip type fixing device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Belt, 1a ... Belt base material, 1b ... Coat layer, 2 ... Roll group, 2a ... Steering roll, 3 ... Belt position detection apparatus, 4 ... Swing detection arm, 5 ... Elastic roller, 5a ... Elastic layer, 5b ... roller base material, 6 ... positioning member, 7 ... heat fixing roll, 8 ... assist member, 9 ... recording material

Claims (7)

In a belt conveyance device that arranges a plurality of roll groups including at least tiltable steering rolls for meander adjustment in parallel, spans an endless belt around these roll groups, and circulates and conveys the belts.
It has a wire-like swing detection arm that swings according to the movement of the belt end position and detects the belt position, and at least a surface is provided at a position corresponding to the contact portion with the belt end of the swing detection arm. A belt position detecting device for a belt conveying device, wherein an elastic roller having an elastic layer as a part is rotatably mounted around a swing detecting arm itself . In claim 1,
The swing detection arm is placed opposite the end of the belt area where the relative position changes according to the tilting of the steering roll, and the length of the elastic roller is set larger than the relative movement of the belt. A belt position detecting device for a belt conveying device. In claim 1,
  The belt position detecting device of the belt conveying device, wherein the elastic roller is mounted in a state of being positioned on the swing detecting arm. In claim 3 ,
The elastic roller is positioned by a positioning member fixed to the swing detection arm. In claim 1,
A belt position detecting device for a belt conveying device, wherein the elastic layer of the elastic roller is a heat shrinkable tube. In the aspect in which the elastic roller is composed only of an elastic body among the ones according to claim 1,
A belt position detecting device for a belt conveying device, wherein both ends of the elastic roller are covered with a protective member fixed to a swing detecting arm. In claim 4 ,
The positioning member includes a through hole having a diameter equal to that of the swing detection arm.

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