JP3868032B2 - Conveyor belt unit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a transport belt unit that is provided in an automatic document feeder used in, for example, a copying machine and includes a transport belt that transports a document.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, for example, in a copying machine, an automatic document feeder that is mounted on a copying machine body and automatically supplies a document to a predetermined position on the copying machine body and discharges the document from the copying machine body is known. There are various types and shapes of automatic document feeders, and an example is the type shown in FIG.
[0003]
Referring to FIG. 9, automatic document feeder 1 is mounted on the upper part of copying machine 2. The originals are collectively placed on the placement plate 5 of the original placement unit 4. When the original is placed, the moving unit 14 moves along the direction of the arrow 13 in accordance with the original size, and the setting of the original is completed. Each document is drawn into the document supply unit 6 one by one, sent along the paper feed path 7, and placed on the contact glass 9 of the copier body 3 by the transport belt 8. The copying machine main body 3 performs a predetermined image forming operation on the original. Thereafter, the document is sent to the document discharge unit 10 by the conveyance belt 8 and is discharged again to the document placement unit 4 through the discharge path 11. The moving unit 14 moves forward and backward with respect to the document discharge unit 10.
[0004]
By the way, the conveyance belt 8 is attached to the frame 15 and is driven by a motor (not shown). The conveyor belt 8 needs to be replaced with a new one depending on the degree of dirt or abrasion, and conventionally, the replacement operation has been performed as follows. 10 to 14 show the replacement work of the conveyor belt 8.
Referring to FIG. 10, first, when the set screw 16 is removed, the frame 15 (see FIG. 9) rotates in the direction of the arrow 17 to be in a state as shown in FIG. 10 (so-called cantilever state). Then, when the tension member 18 provided on the frame 15 is rotated (folded) in the direction of the arrow 19, the conveying belt 8 to which tension is applied while being stretched by the tension member 18 is as shown in FIG. To relax.
[0005]
More specifically, referring to FIG. 12, the tension member 18 is provided with a support shaft 20 that is elastically biased to the right side in the drawing by a tension coil spring 23, and the support shaft 20 is attached to the frame 15. The slide groove 21 is provided. Thereby, the tension member 18 is rotatably supported by the frame 15 and is slidable along the direction of the arrow 22. On the other hand, a locking projection piece 24 projects from the frame 15 side. As a result of the tension member 18 being slid to the right side in the drawing by the tension coil spring 23, the locking protrusion 24 engages with the locking groove 25 provided in the tension member 18. Thereby, the conveyor belt 8 is mounted in a pulled state.
[0006]
In order to remove the transport belt 8, as shown in FIG. 13, the tension member 18 is slid to the left in the drawing, that is, against the elastic force of the tension coil spring 23. In this state, no tension is generated in the transport belt 8, so that the tension member 18 can be easily rotated in the direction of the arrow 26, resulting in the state shown in FIG. Then, the conveyance belt 8 is pulled out toward the front side in the direction perpendicular to the paper surface as it is, and then replaced with a new conveyance belt. The new conveyor belt can be attached by performing the reverse operation of the above-described removal operation.
[0007]
[Problems to be solved by the invention]
Although the replacement operation of the conveyor belt 8 is performed as described above, there have been the following problems.
To attach a new transport belt, first, the transport belt is put on the frame 15 so as to be in the state shown in FIG. And, from this state, the tension member 18 is rotated to mount the conveyor belt, but the tension member 18 is always elastically biased by the tension coil spring 23 in the direction of applying tension to the conveyor belt. The tension member 18 is once slid to the left in the drawing against the elastic force of the tension coil spring 23, and the conveyor belt must be attached in this state. For this reason, there was a problem that it was very difficult for the operator to work.
[0008]
SUMMARY OF THE INVENTION An object of the present invention is to provide a conveyor belt unit that can easily perform a conveyor belt replacement operation.
[0009]
[Means for Solving the Problems]
  In order to achieve the object of the present invention, a conveyor belt unit according to claim 1 is a conveyor belt unit that wraps an endless conveyor belt between a first roller and a second roller, and conveys an original by the conveyor belt. The first roller is provided at one end, and is attached to the main frame extending in the direction in which the belt is hung and slidable along the extending direction of the main frame. It is rotatable with respect to the main frame in a state where it is slid in the anti-extension direction against the urging force, and the second roller is attached to the end portion in the extension direction and is rotated with respect to the main frame. A sub-frame in which the second roller is configured to deviate from the extending direction of the main frame;With,A longitudinal slide groove is formed in the other end portion of the main frame along the extension direction, and a pin is protruded from the end portion on the side opposite to the extension direction of the sub frame, and both are engaged. The sub frame is slidable with respect to the main frame,Lock the sub-frame to the main frame while sliding the sub-frame in the opposite direction.forLocking mechanismThe locking mechanism includes an extending groove extending in a direction intersecting with the extending direction continuously on the anti-extending direction side of the slide groove, and the sub-frame is bent in the extending groove. A recess is formed to hold the pin at a predetermined position of the extending groove so as to lock the end of the subframe in the extending direction side while being slid in the extending direction. In order to maintain the state in which the pin is held in the recess, a spring is provided that applies a force to the pin in the extending direction of the extending groove and elastically biases the subframe in the extending direction at all times. Has beenIt is characterized by this.
[0010]
  According to this configuration, the sub-frame can be locked with respect to the main frame in a state where the distance between the first roller and the second roller is reduced by sliding the sub-frame when the transport belt is replaced..
[0011]
SThe distance between the rollers can be changed by moving a pin provided on the frame along a slide groove formed on the main frame. When the pin is inserted into the extended groove extending in the slide groove, the extended groove is formed in the crossing direction with respect to the slide groove, so that the pin can be held in the extended groove. it can.
[0013]
AdditionIf the pin is inserted into the extended groove extending in the slide groove, the pin can be held in the extended groove by the recess. Therefore, the sub-frame can be securely locked to the main frame in a state where the distance between the first roller and the second roller is reduced.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a cross-sectional view showing the structure of a copying machine A employing a conveyor belt unit 600 according to an embodiment of the present invention. Referring to FIG. 1, this copying machine A is mounted on a copying machine main body 50 and an upper portion of the copying machine main body 50, and an air-fed circulating document conveying apparatus (hereinafter referred to as an automatic feeding apparatus) that automatically supplies a document to the copying machine body 50 side. The RDH 100 is rotatably attached to the copying machine main body 50 and covers the upper part of the copying machine main body 50 (the state shown in the figure). And can be displaced to an open state.
[0015]
The present invention relates to the RDH 100, and the conveyor belt unit 600 is attached to the RDH 100. Hereinafter, a schematic configuration and functions of the RDH 100 will be described.
The RDH 100 includes a document placement unit 200 for placing a document, a moving unit 300 for positioning and placing the placed document, and a document for supplying the placed document to the copier body 50. In order to feed the originals one by one to the supply unit 400, the original separation mechanism 500 for separating the set originals, and the original supplied to the copier main body 50 side in the supply direction or the reverse direction. A conveyance belt unit 600 for moving in the supply direction and a document discharge unit 700 for discharging a document from the copying machine main body 50 side are provided.
[0016]
Next, the function of each part of the RDH 100 will be generally described. First, a document (not shown) is placed on the placement plate 210 of the document placement unit 200. The RDH 100 according to the present embodiment can set a B5-A3 size document. Therefore, the positioning plate 250 arranged to face the reference plate 230 is moved (moved in the direction perpendicular to the paper surface in the drawing) according to the document size. Thus, each size document can be positioned between the reference plate 230 and the positioning plate 250 in the direction perpendicular to the paper surface in the drawing.
[0017]
On the other hand, when a document is placed, this is detected by a document presence / absence sensor 295 installed below the placement plate 210, and based on this and the aforementioned document size information, the moving unit 300 moves in the direction of the arrow P1 in the figure. Moving. As a result, the document can be positioned in the horizontal direction in the figure. Further, the moving unit 300 is provided with a document pressing mechanism 310, and the pressing bar 311 is temporarily turned up in the direction of the arrow P3 and then laid down, whereby the trailing end portion of the document is pressed. Thus, the document setting is completed with the document positioned in two directions.
[0018]
The document set on the document placement unit 200 is guided to the document supply unit 400 and sent along the sheet feed path 402 by the pair of sheet feed rollers 401, and then placed on the contact glass 51 of the copier body 50. The
Reference numeral 403 indicates a registration roller pair. The registration roller pair 403 is for temporarily stopping the document fed along the paper feed path 402 and feeding it onto the contact glass 51 in the paper feed path 402. Reference numeral 404 indicates a reversing roller pair. The reversing roller pair 404 is for reversing a so-called double-sided original, and pulls back the original once placed on the contact glass 51 and sends it along the reverse path 405. The inverted document is fed again onto the contact glass 51 through the registration roller pair 403.
[0019]
The document separation mechanism 500 separates the document using air before the document is guided to the document supply unit 400, and a method of separating the document using air is known (Japanese Patent Laid-Open No. 61-291339). No. publication). This document separation mechanism 500 is designed to pull the document placed in order from the lowest document among the placed documents, and is sucked by a document suction unit 510 that sucks the lowermost document by air. A document floating unit 550 that floats the document on the upper side of the document with air, and a document drawing unit 570 for drawing the sucked document to the document supply unit 400 side.
[0020]
Specifically, the document suction unit 510 sucks air from the suction port 512 of the suction duct 511 opened on the mounting plate 210 by driving a suction fan (not shown) to suck the lowermost document. It is supposed to be attached. Further, the document levitation unit 550 blows air from the air blowing port 552 of the air duct 551 by driving a blower fan (not shown), so that the document on the upper side of the lowermost document is lifted. Further, the document drawing portion 570 has an endless drawing belt 571. The pull-in belt 571 is placed around the rollers 513 and 514 so as to cover the suction port 512. The drawing belt 571 has a plurality of through holes (not shown). Therefore, when air is sucked from the suction port 512, the lowermost document is sucked into each through hole. It will be in the state adhering to the drawing-in belt 571. The roller 513 is driven by a motor (not shown) and the pull-in belt 571 is driven in the direction of the arrow P2, so that the lowermost document is drawn and guided to the document supply unit 400.
[0021]
The document placed on the contact glass 51 is sent to the document discharge unit 700 by the transport belt unit 600 after a predetermined copying operation is performed by the copying machine body 50. The conveyor belt unit 600 is disposed opposite to the contact glass 51 in the state shown in the figure, and is driven by a motor (not shown). Thereby, the document on the contact glass 51 is sent to the document discharge unit 700 side. When the document is reversed, the conveyance belt unit 600 is rotated in the reverse direction so that the document is fed to the reverse roller pair 404 side.
[0022]
A document sent to the document discharge unit 700 is drawn into a discharge path 702 by a discharge roller pair 701. Thereafter, the original is fed along a paper discharge path 702 by a pair of paper discharge rollers 703 and is again discharged onto the document placement unit 200 by a pair of paper discharge rollers 704 and 705. The moving unit 300 moves forward and backward with respect to the document discharge unit 700, and a part of the paper discharge path 702 (downstream in the paper discharge direction) is between the document discharge unit 700 and the moving unit 300. It is comprised by the clearance gap formed in between. Further, since the moving unit 300 advances and retreats with respect to the document discharge unit 700, the paper discharge roller pair 705 is provided on the moving unit 300 side, and moves as the moving unit 300 moves. Yes.
[0023]
A feature of the present embodiment is that the conveyance belt unit 600 includes a conveyance belt 601 that contacts the document and conveys the document, so that the replacement operation of the conveyance belt 601 can be performed easily and accurately. It is in the point. Hereinafter, the conveyance belt unit 600 will be described in detail.
FIG. 2 is a perspective view of a main part of the frame 602 of the conveyor belt unit 600. Referring to FIGS. 1 and 2, the conveyor belt unit 600 has a frame 602 and a conveyor belt 601 attached to the frame 602. In the state shown in FIGS. The bottom of the casing 115 is rotatably attached.
[0024]
The frame 602 includes a main body 603 (main frame) and a tension member 604 (subframe) that is rotatably attached to the main body 603. Belt support rollers 605 and 606 are provided on one end side of the main body 603 and the tip end side of the tension member 604. By sliding the tension member 604 in the direction of arrow 607 in FIG. The distance between the belts 606 can be extended to apply tension to the conveyor belt 601. In FIG. 2, the distance between the belt support rollers 605 and 606 is extended.
[0025]
The main body 603 can be assembled using, for example, bone members 608 and 609 having a substantially U-shaped cross section. Although only a part of the main body 603 is shown in FIG. 2, a rectangular frame is formed as a whole. A plate member 606 is attached to the inside of the main body 603 so as to improve the rigidity of the main body 603. The plate member 606 is appropriately formed with a cut-out hole 607. Although not shown in the drawing, a roller or the like is disposed inside the cut-out hole 607 to suppress the bending of the wound conveyor belt 601. It has come to be. In addition, the weight of the main body 603 can be reduced by the punched holes 607.
[0026]
In the opposing bone members 608, L-shaped through grooves 610 are formed at positions facing each other. The through groove 610 guides the slide of the tension member 604, and includes a slide groove portion 611 and an extended groove portion 612 that extends upward perpendicularly to the slide groove portion 611. The groove width of the through groove 610 corresponds to the outer diameter of the pin 613 provided in the tension member 604. FIG. 3 is an enlarged view of the through groove 610. With reference to FIG. 3, a recess 614 into which a part of the pin 613 can be fitted is formed in the extending groove 612. The recess 614 can temporarily hold the pin 613 by fitting the pin 613 (see FIG. 7). In addition, it is preferable that the shape of the wall surface constituting the recess 614 corresponds to the outer diameter of the pin 613.
[0027]
Referring to FIG. 2 again, projecting pieces 616 are provided at the other ends of the opposing bone members 608, respectively. The protruding piece 616 is for holding the tension member 604 in the state shown in the figure (a state where the distance between the belt support rollers 605 and 606 is extended) by engaging with the tension member 604.
Next, the tension member 604 has a pair of connection plates 615 connected to the main body 608 of the frame 602, and a belt support roller 606 provided so as to span between the front ends of both connection plates 615. . The belt support roller 606 is rotatably supported by a shaft 617. Referring to FIG. 1, a belt support roller 605 provided on one end side of the main body 603 is also similar to the belt support roller 606, and is rotatable to the main body 603 via a rotation center shaft (not shown). Is attached.
[0028]
Referring to FIG. 2, a pin 613 protrudes from the base end portion of the connecting plate 615. As described above, the pin 613 is inserted into the through groove 610 provided in the main body 603, so that the tension member 604 is rotatable with respect to the main body 603 along the direction of the arrow 619 and the arrow 619. It is slidably attached along the direction of 607.
[0029]
An engaging groove 618 with which the protruding piece 616 can be engaged is formed on the distal end side of each connecting plate 615. The engagement groove 618 is cut downward from the upper edge 620 of the connecting plate 615 in the drawing, and is further extended by a predetermined length to the base end side (side from which the pin 613 protrudes). Therefore, in order for the protruding piece 616 to engage with the engaging groove 618, the connecting plate 616 is rotated to insert the protruding piece 616 from the opening 621 of the engaging groove 618, and then the connecting plate 616 is slid. Accordingly, it is necessary to move the projecting piece 616 along the engaging groove 618.
[0030]
In this embodiment, a tension coil spring (hereinafter referred to as “spring”) 622 is interposed between the bone member 609 of the main body 603 and the pin 613. As a result, the pin 613 is always elastically biased in the direction of the arrow 607. That is, the tension member 604 is always urged in the direction of the arrow 607, and as a result, the distance between the belt support rollers 605 and 606 is always increased.
[0031]
With reference to FIG. 1, the conveyance belt 601 can be configured by coating a soft synthetic resin on a cloth belt, for example. The transport belt 601 is an endless belt, and is mounted so as to be hung between the belt support rollers 605 and 606. When the belt support roller 605 is driven, the conveying belt 601 is sent so as to circulate along the longitudinal direction of the frame 602, and the document is conveyed by the conveying belt 601 sent in this way. Yes.
[0032]
By the way, since the conveyance belt 601 conveys the document while being in contact with the document, it may be soiled or damaged in some cases. For this reason, the conveyance belt 601 is a component that should be periodically replaced. Such replacement parts are preferably easy to replace. In the conveyor belt unit 600 according to the present embodiment, the conveyor belt 601 can be replaced as follows.
[0033]
(1) First, referring to FIG. 4, this figure shows a state in which the conveyor belt 601 is mounted, and the tension member 604 is urged to the right side in the drawing by the elastic force of the spring 622. That is, the distance between the belt support rollers (605) and 606 is increased, and tension is applied to the conveyance belt 601. Therefore, in this state, the conveyor belt 601 cannot be removed.
[0034]
(2) Referring to FIG. 5, when the belt support roller 606 is gripped by hand and the tension member 604 is pressed to the left in the figure against the elastic force of the spring 622, the pin 613 slides along the slide groove 611. To do. As a result, the distance between the belt support rollers (605) and 606 is reduced, and the conveyor belt 601 is slightly loosened (no tension is generated). In addition, the projecting piece 616 moves relative to the engagement groove 618 to the right and is disposed at the position of the opening 621 of the engagement groove 618.
[0035]
(3) Referring to FIG. 6, when the tension member 604 is rotated clockwise in the figure, the conveying belt 601 is hung downward in the figure. In this state, the conveying belt 601 can be easily removed by pulling it out in the direction perpendicular to the paper surface.
(4) Next, a new conveyor belt 601 is attached. Since the tension member 604 is in the state shown in FIG. 6, this attachment can be easily performed by covering the conveyance belt 601 on the frame 602. Then, the tension member 604 is rotated leftward in the drawing.
[0036]
{Circle around (5)} At this time, as shown in FIG. 7, the pin 613 is once inserted into the extending groove 612 and fitted into the recess 614. As a result, the pin 613 is temporarily held in the extending groove 612 by the recess 614. As a result, the proximal end portion of the tension member 604 is locked at the position shown in the drawing, and the belt support rollers (605) and 606 are interposed. The state where the distance is reduced can be maintained. In addition, in this state, no tension is generated in the conveyor belt 601, so that the position of the conveyor belt 601 can be corrected and the belt support rollers (605) and 606 and the frame 602 can be tilted and correctly arranged. .
[0037]
In particular, in the present embodiment, the mounting position of the spring 622 is such that the pin 613 is pulled upward by a predetermined angle a in the state shown in FIG. It is set so that force is applied in the direction of pulling upward. Therefore, the pin 613 is not carelessly removed from the recess 614 during the operation, and the tension member 604 does not slide to the right side, and the state where the distance between the belt support rollers (605) and 606 is reliably reduced is maintained. can do.
[0038]
(6) After correcting the position of the conveyor belt 601, the belt support roller 606 is pushed up. That is, the tension member 604 is rotated in the direction of the arrow 625 with the projecting piece 616 projecting from the main body 603 as a fulcrum. As a result, the pin 613 fitted in the recess 614 is released and enters the slide groove 611 as shown in FIG. Thereafter, since the pin 613 is pulled by the spring 622 and slides along the slide groove 613, the distance between the belt support rollers (605) and 606 increases along the longitudinal direction of the frame 602, and tension is applied to the conveyor belt 601. Is granted.
[0039]
As described above, according to the transport belt unit 600 according to the present embodiment, when the transport belt 601 is replaced, the distance between the belt support rollers 605 and 606 is reduced in advance, and a new transport belt 601 is installed in this state. After being hung along the longitudinal direction of the frame 602, the position thereof is corrected and arranged correctly, and the distance between the belt support rollers 605 and 606 is linearly increased along the longitudinal direction of the frame 602. Since tension is applied to the conveyor belt 601, the conveyor belt 601 can be easily attached to the frame 602. In addition, the transport belt 601 is not displaced at the time of mounting. The spring 622 also prevents the tension member 604 from being inadvertently slid to the right side during the replacement operation of the conveyor belt 601, so that the position correction operation of the conveyor belt 601 can be easily performed. is there.
[0040]
In addition, in the present embodiment, the through grooves 610 and 630 are provided as means for temporarily holding the pin 613 and locking the base end portion of the tension member 604 so that the distance between the two belt support rollers 605 and 606 is reduced. Therefore, there is an advantage that the structure for locking the tension member 604 can be simplified, and the transport belt unit 600 can be manufactured at low cost.
[0041]
In addition, this invention is not limited to the said embodiment, The following design changes can be given. FIG. 8 is a diagram illustrating a design change example of the through groove 610 (see FIG. 3) provided in the main body 603.
Referring to FIG. 8, the through groove 630 according to the present design modification is different from the through groove 610 in that the recess 614 provided in the extended groove 612 of the through groove 610 corresponds to the outer diameter of the pin 613. In contrast to the configuration of the so-called rounded surface, in the present design modification example, the concave portion 632 formed in the extended groove portion 631 has the groove width of the extended groove portion 631 along the extending direction of the extended groove portion 631. It is in the point comprised by the curved inclined surface which expands gradually. Even if the concave portion 632 is formed by such an inclined surface, the pin 613 can be temporarily held in the extending groove portion 631 as shown in the drawing.
[0042]
In this embodiment, the concave portions 614 and 632 are provided to temporarily hold the pin 613. However, by appropriately setting the coefficient of friction between the pin 613 and the extending groove portions 612 and 633, the spring 622 is provided. A predetermined frictional force is generated between the two by the elastic force, and the pin 613 can be temporarily held in the extending groove portions 612 and 631. That is, the recesses 614 and 632 can be eliminated.
[0043]
In the present embodiment, the through grooves 610 and 630 are employed to temporarily hold the pin 613. However, the pin 613 can be locked at a position where the distance between the belt support rollers 605 and 606 is small, and desired. Other mechanisms may be used as long as the mechanism can release the locking state and increase the distance between the belt support rollers 605 and 606.
[0044]
【The invention's effect】
According to the first aspect of the present invention, the distance between the first and second rollers that support the conveyor belt is previously reduced during the replacement operation of the conveyor belt, and the new conveyor belt is extended from the main frame in this state. Since the tension can be applied to the conveyor belt by sliding the sub-frame with respect to the main frame after being hung along the direction, it is very easy to mount the conveyor belt. As a result, it is possible to prevent the transport belt from being displaced and to mount it accurately.
[0045]
According to the invention of claim 2, the same effect as that of the invention of claim 1 is obtained. In addition, in order to keep the distance between the rollers small, a very simple structure is adopted in which the pin provided in the subframe is fitted into the recess of the extension groove provided in the main frame, which greatly increases the cost. There is an advantage that it is not boring.
According to the invention of claim 3, the same effect as that of the invention of claim 2 is obtained. In addition, since the distance between the rollers can be surely reduced by the holding means, the locked state is not inadvertently released during the replacement operation of the conveyor belt, and mounting errors can be suppressed as much as possible. it can.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing the structure of a copying machine according to an embodiment of the present invention.
FIG. 2 is a perspective view of a main part of a main body of a conveyor belt unit according to the present embodiment.
FIG. 3 is an enlarged view of a through groove.
FIG. 4 is a side view of a main part of the transport belt unit in a state where the transport belt is mounted.
FIG. 5 is a side view of a main part of the transport belt unit in a state where a distance between belt support rollers is reduced.
FIG. 6 is a side view of a main part of the transport belt unit in a state where a tension member is rotated.
FIG. 7 is a side view of a main part of the conveyor belt unit in a state where pins are temporarily held.
FIG. 8 is a diagram showing a design change example of a through groove.
FIG. 9 is a schematic diagram illustrating an example of a conventional automatic document feeder.
FIG. 10 is a perspective view of an essential part showing an operation of rotating and raising the automatic document feeder and removing the conveyor belt device.
FIG. 11 is a perspective view of a main part showing an operation of removing the conveyor belt.
FIG. 12 is a side view of the conveyor belt unit in a state where the conveyor belt is attached.
FIG. 13 is a side view of a main part of the conveyor belt unit showing a state in which a tension member is slid in order to remove the conveyor belt.
FIG. 14 is a side view of a main part of the conveyor belt unit showing a state in which a tension member is rotated in order to remove the conveyor belt.
[Explanation of symbols]
100 RDH
600 Conveyor belt unit
601 Conveyor belt
602 frames
603 body
604 Tension member
605 belt support roller
606 Belt support roller
610 Through groove
611 Slide groove
612 Extension groove
613 pin
614 recess
615 connecting plate
616 Projection
618 engaging groove
622 spring
630 Through groove
631 Extension groove
632 recess

Claims (1)

In a transport belt unit that wraps an endless transport belt between the first roller and the second roller and transports the document by the transport belt,
A main frame provided with a first roller at one end and extending in a direction around which the belt is wound;
It is slidably mounted along the extension direction of the main frame, and is always elastically biased in the extension direction, and is rotatable with respect to the main frame in a state of sliding in the anti-extension direction against the elastic biasing force. , and the and the second roller is mounted on the extending direction side end portion, by rotating relative to the main frame, and a subframe the second roller is to deviate from the extension direction of the main frame Prepared ,
A longitudinal slide groove is formed in the other end portion of the main frame along the extension direction, and a pin is protruded from the end portion on the side opposite to the extension direction of the sub frame, and both are engaged. The sub frame is slidable with respect to the main frame,
The sub-frame in a state in which slide the sub-frame to the opposite extension direction a locking mechanism for the for locking relative to the main frame, the locking mechanism is continuously in the counter-extension direction of the slide groove And extending in a direction crossing the extension direction, and the extension groove has an end in the counter-extension direction side of the sub-frame in a state where the sub-frame is slid in the counter-extension direction. A recess is formed to hold the pin at a predetermined position in the extending groove,
In order to maintain the pin of the subframe held in the recess, a force is applied to the pin in the extending direction of the extending groove, and the subframe is always elastically biased in the extending direction. A conveyor belt unit characterized in that a spring is provided .

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