JPH0940245A - Copying machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a copying machine which can surely prevent a jam that may result from the setting of the end of a roll sheet in a slanted position at the time of replacement of a roll. SOLUTION: When replacement of the roll 4C1 of a roll sheet 4C is complete and a safety switch is turned off with a front door closed, a supply reel is driven correspondingly to move the roll sheet 4C back and forth plural times along its feed direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying machine for recording an image on a roll sheet pulled out from a roll body.

[0002]

2. Description of the Related Art In recent years, an electrostatic copying machine has been provided which is capable of copying a large-sized original such as Japanese Industrial Standard A-row No. 0 (hereinafter referred to as "A0 size"). Has reached. "A0 size" here is one of the finished dimensions of paper according to Japanese Industrial Standards,
It refers to the size of 841 (mm) x 1189 (mm).

Since it is difficult to handle large copy sheets such as the A0 size one by one, it is usual to roll a continuous strip-shaped copy sheet around a core rod. The roll sheet accommodated in the main body of the copying machine is applied in the state where the sheet is formed. The above roll body is set by the user in the main body of the copying machine in a state where a predetermined amount of roll sheet is pulled out from the roll body.

By the way, the leading end of the pulled-out roll sheet must be accurately set at a predetermined setting position on the conveying path. Therefore, when the roll body is set, the roll sheet is once sent out from the roll body to be fed, the leading edge of the roll sheet reaches the sheet leading edge detection switch, and then the roll sheet is rewound by a predetermined amount (for example, 10 mm), The tip is accurately aligned with the set position.

[0005]

By the way, there are cases where the user sets the roll sheet pulled out from the roll body in a state of being bent in the conveying path. In this case, the leading end of the roll sheet is orthogonal to the conveying direction. They are not aligned on the line and are diagonal. If the sheet is fed with the tip thereof being slanted in this manner, the roll sheet is slantedly conveyed, which may cause a jam.

On the other hand, as described above, after the roll body is set, the inclined state of the leading edge is caused by a series of operations for feeding out and rewinding the leading edge of the roll sheet, which is performed for aligning the leading edge of the roll sheet. May be alleviated, but I couldn't expect much. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a copying machine that can reliably prevent the occurrence of a jam due to the tip of a roll sheet being displaced obliquely when being set.

[0007]

In order to solve the above-mentioned problems, 1) the invention according to claim 1 forms an image by an electrophotographic method and pulls it out from a roll body formed by winding a long sheet. Image forming part to transfer to a rolled roll sheet,
In a copying machine having a conveyance path for guiding the pulled-out roll sheet to an image forming unit, and the leading end of the pulled-out roll sheet is set at a predetermined setting position in the conveyance path, the roll body is integrally rotated. A supply reel capable of sending the roll sheet from the roll body and rewinding the roll sheet by being normally and reversely rotated, a drive system for driving the supply reel so as to be capable of forward and reverse rotation, and a roll. In accordance with the input of a predetermined signal related to the completion of body exchange, a control means for operating the drive system to move the roll sheet back and forth a plurality of times in the transport direction. is there.

According to the above construction, when a predetermined signal related to the completion of the exchange of the roll body is input, the supply reel is driven in response to this, and the feeding and rewinding of the roll sheet are repeated a plurality of times. Thus, the skew correction is performed so that the leading edge of the roll sheet is aligned with the line orthogonal to the transport direction. Here, the predetermined signal related to the completion of the roll body exchange may be a signal from a switch operated by an operator, or a signal that detects an operation necessarily performed when the roll body is exchanged, for example, a door. It may be a signal from a switch that detects the opening and closing of. 2) The invention according to claim 2 is the copier according to claim 1, further comprising a door for opening at least a part of the inside of the copier for roll replacement, and a predetermined unit related to completion of the roll replacement. The signal is a signal related to opening and closing of the door.

According to the above construction, when the roll body is replaced and the door is closed, the skew correction is automatically performed.

[0010]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. 1 is a schematic cross-sectional view of the internal structure of a copying machine according to an embodiment of the present invention, FIG. 2 is a perspective view showing the external structure, and FIG. 3 is a perspective view showing the external appearance of the copying machine during copying. It is a figure. This copying machine is for obtaining a copied image of a large-sized original such as A0 size. In this copying machine, while a document is being conveyed, the surface of the document is illuminated and scanned by an optical system fixedly arranged, and an image is formed based on this illumination and scanning.

Referring to FIG. 1, the main body 1 of the copying machine is provided with caster wheels 2 at its bottom portion so that it can be moved freely. 1 to 3, the copying machine main body 1
A document transport unit 10 for transporting a document 9 along a document transport path 41 formed on the upper surface of the copying machine body 1 is provided above the document transport unit 10.
Is provided. The front surface 1a of the copying machine main body 1 is provided with a discharge port 54 for discharging the sheet on which the toner image is transferred. The sheet discharged from the discharge port 54 is
As shown in FIG. 3, while being guided by the guide member 91, it is dropped with its front end facing downward and is sequentially accommodated in the pocket 92 formed by the front cover 5 along the front surface 1a of the copying machine body 1 through the introduction opening 93. It is like this.
Further, at the end of the upper surface of the copying machine main body 1, there is provided an operation unit 100 having switches, keys and the like for making various settings related to copying.

With reference to FIG. 1, a roll body 4A1, 4B1 and 4C1 is wound around a winding core in a roll shape in a portion below a central portion in a height direction inside the copying machine main body 1. Roll sheets 4A, 4 of upper, middle, and lower three stages, which are respectively configured
B and 4C are housed. Each roll body 4A1, 4B
1 and 4C1 are supply reels 51, 52 and 5, respectively.
3 is rotatably supported integrally with the roll sheet 4 by being driven by a sheet feeding motor DM described later.
A, 4B and 4C can be fed and wound respectively. These roll sheets 4A, 4
Examples of types of B and 4C include plain paper, film, tracing paper, and the like.

In addition, a cut sheet of A0 size to A4 size or the like, which is cut in advance to a predetermined length, is supplied to the central portion of the copying machine main body 1 through a manual paper feeding section 30 on the front surface 1a of the copying machine main body 1. A bypass sheet feeding path D4 is provided for this purpose. Referring to FIG. 11, at least a part of the front surface 1a of the copying machine main body 1 is configured as a front door 1b which can be opened when the rolls of the roll sheets 4A, 4B and 4C are exchanged. A front door opening / closing sensor 110 for detecting opening / closing of the front door 1b is arranged in the main body 1. In FIG. 11, the illustration of the front cover 5 for forming the pocket 92 is omitted.

The roll sheet 4A on the upper stage is composed of the supply reel 51, the paper feed roller 61, and the roll sheet 4A to be conveyed.
A first leading edge detection switch 71 for detecting the leading edge of the sheet, a conveyance roller 62, a cutter mechanism 80, a registration roller 63, a second leading edge detection switch 72 for detecting the leading edge of each of the conveyed sheets 4A, 4B, 4C, 4D, Then, the sheet is conveyed along the first sheet feeding path D1 reaching the photoconductor drum 20 through the conveying roller 33 in sequence.

The roll sheet 4B in the middle stage is provided with the supply reel 5
2, a paper feed roller 64, a third leading edge detection switch 73 for detecting the leading edge of the conveyed roll sheet 4B, a conveyance roller 62, a cutter mechanism 80, a registration roller 63, a second leading edge detection switch 72, and a conveyance roller 33. Is sequentially conveyed along the second paper feed path D2 to the photoconductor drum 20. The path after the transport roller 62 is common to the first paper feed path D1.

The lower roll sheet 4C is the supply reel 5
3, the paper feed roller 65, a fourth leading edge detection switch 74 for detecting the leading edge of the rolled roll sheet 4C, the feeding roller 62, the cutter mechanism 80, the registration roller 63, the second leading edge detection switch 72, and the feeding roller 33. Is sequentially conveyed along the third sheet feeding path D3 to the photosensitive drum 20. The path after the transport roller 62 is common to the first paper feed path D1.

The bypass sheet feeding path D4 is provided with a fifth leading edge detection switch 75 for detecting the leading edge of the cut sheet 4D introduced from the manual sheet feeding section 30 and a sliding contact plate (not shown). Separation roller 3 for separating cut sheets (separating them one by one) by sliding them against each other
2. A path leading to the photosensitive drum 20 through the sixth leading edge detection switch 76 for detecting the leading edge of the conveyed cut sheet, the registration roller 39, the second leading edge detection switch 72, and the conveyance roller 33 in this order. is there. The path of the bypass paper feed path D4 after the second leading edge detection switch 72 is common to the first paper feed path D1.

The first to third sheet feeding paths D1 to D3 and a transportation path 34 described later constitute a transportation path for the roll sheet 4. In addition, the supply reels 51 to 5
3, the transport rollers 61, 62, 64, 65, the registration roller 63, the transport roller 33, the fixing heat roller 37 and the pressure roller 38, and the discharge roller 36 constitute transport means.

Further, the cutter mechanism 80 has a long fixed blade 81 extending in a direction orthogonal to the conveying direction of the roll sheet 4A, 4B or 4C in the casing 80A, and between the fixed blade 81. , The roll sheets 4A, 4 being conveyed
And a rotary blade 82 for cutting B or 4C. Each roll sheet 4A, 4 when being conveyed through the cutter mechanism 80
The transport directions of B and 4C are upward. The rotary blade 82 stands by at the home position in the rotation direction shown in FIG. 1, rotates and cuts when necessary, and then returns to the home position again. The home position detection switch 503 for detecting the home position of the rotary blade 82 is
It is provided on the rotary blade 82.

The original document transport unit 10 switches the transport direction to the forward direction R1 or the reverse direction R2 and transports the original document 9. The image forming operation is performed when the document is conveyed in the forward direction R1. When a plurality of sheets are copied from the same original document, the original document transporting unit 10 transports the original document 9 by alternately switching the transport direction between the forward direction R1 and the reverse direction R2. Further, on the upper surface of the copying machine body 1, the forward direction R1
With respect to the document transport section 10, the above-described document transport path 41 is formed up to a position where it projects from the upper surface of the copying machine body 1.

The above-described document conveying section 10 has a first document edge detecting switch 11, a first conveying roller 12, a second document edge detecting switch 16, a second conveying roller 14 along the forward direction R1. And the third conveying roller 15 are sequentially arranged. The first transport roller 12 is started to be driven when the first document end detection switch 11 is switched from OFF to ON and detects the leading end of the document 9 (the end on the downstream side in the forward direction R1). The second transport roller 14 is provided at a position facing the transparent plate 13 for slit exposure of the document 9, and brings the document 9 into close contact with the transparent plate 13. The third transport roller 15 discharges the exposed original document 9.

The second document edge detection switch 16 is also provided.
Is switched from OFF to ON when the document 9 is conveyed in the forward direction R1, and thus the document 9 in the forward direction R1 is
Detect the tip of. This second document edge detection switch 16
Depending on that the roll sheet is turned on, the roll sheet 4A, 4B or 4C (hereinafter, the roll sheet A, 4B or 4C conveyed for transfer is simply referred to as "roll sheet 4").
Is started, and as a result, the original and the roll sheet 4 are synchronized.

The first document edge detection switch 11 is also provided.
Is switched from ON to OFF when the document 9 is conveyed in the forward direction R1, so that the document 9 in the forward direction R1
Detect the rear edge of. The cutter mechanism 80 is driven and the roll sheet 4 is cut at a predetermined timing after a predetermined time has elapsed from the timing of this detection. In the present embodiment, the length of the sheet feeding path of the roll sheet 4 from the cutter mechanism 80 to the transfer position 20b of the transfer corona discharger 24 is set so that the document feed position from the first document edge detection switch 11 to the document exposure position 44 is increased. It is set to be longer than the length of the paper path by the length from the exposure position 20a of the photoconductor drum 20 to the transfer position 20b. As a result, an image corresponding to the trailing edge of the original 9 can be formed on the trailing edge of the roll sheet 4 obtained by cutting at the above timing.

The second document edge detection switch 16 is also provided.
When the document 9 is conveyed in the reverse direction R2, the document 9 is switched from ON to OFF, so that the document 9 in the reverse direction R2 is
Detect the trailing edge of. This second document edge detection switch 16
Is turned off, the transport rollers 12, 14, 1
5 is stopped. At this time, the leading edge of the original 9 is nipped by the conveying roller 12 and is ready for the next copying operation. Reference numeral 8 denotes a reversing member that reverses the direction of the document to prevent the document 9 from falling behind the copying machine body 1.

In relation to the transparent plate 13, a light source 17 as a document scanning means for illuminating the document surface of the document 9 is fixedly arranged. The light from the light source 17 is applied to the document surface through the transparent plate 13. Then, the reflected light from the surface of the original 9 is transmitted by the SELFOC lens 18 to the copying machine body
Is guided to the surface of the photoconductor drum 20 provided in the substantially central portion of. The surface of the photosensitive drum 20 before being exposed by the light from the SELFOC lens 18 is uniformly charged by the charging corona discharger 21. Therefore, an electrostatic latent image corresponding to the original image is formed on the surface of the photosensitive drum 20 after exposure. This electrostatic latent image is visualized as a toner image by the developing device 22. The toner image is guided to the vicinity of the transfer corona discharger 24 as the photosensitive drum 20 rotates in the direction of arrow 23.

On the other hand, the roll sheet 4 guided to the photoconductor drum 20 from each sheet feeding path D1, D2 or D3 is further guided to the vicinity of the transfer corona discharger 24, and the corona discharge of the transfer discharger 24 is performed. Thus, the toner image on the surface of the photoconductor drum 20 is transferred to the roll sheet 4. The roll sheet 4 onto which the toner image is transferred is a corona discharger 2 for peeling.
It is separated from the surface of the photoconductor drum 20 by the corona discharge at 5, and further guided to the fixing device 35 through the conveyance path 34. In the fixing device 35, the toner is fixed on the surface of the roll sheet 4 by heating and pressing the roll sheet 4 between the heat roller 37 and the pressure roller 38. The roll sheet 4 on which the toner is fixed is discharged from the discharge roller 36 to the outside of the copying machine main body 1 via the discharge detection switch 55, and is accommodated in the pocket 92 via the guide member 91 as described above. On the other hand, the toner remaining on the surface of the photoconductor drum 20 after the transfer of the toner image is removed by the cleaning device 26, and preparation for forming the next electrostatic latent image is made. Similarly, the toner image is transferred and fixed on the cut sheet 4D guided from the bypass sheet feeding path D4 to the photoconductor drum 20, and the cut sheet 4D is discharged to the pocket 92.

A guide auxiliary plate 94 is arranged above the guide member 91. This guide auxiliary plate 94
Is a stay 9 attached to the front surface 1a of the copying machine body 1.
The roll sheet 4 is rotatably supported by 5 and is rotated to guide the roll sheet 4 that hangs down in front of the guide member 91 and is discharged to the pocket 92 together with the guide member 91 (indicated by a chain line in FIG. 1). (Shown) and the storage posture held by the stay 95 (shown by the solid line in FIG. 1)
It can be displaced to and.

An image forming section is constituted by the photosensitive drum 20, the developing device 22, the transfer corona discharger 24 and the like. In the present embodiment, a main motor MM for driving the image forming unit and a sheet feeding motor D for driving a roller group for feeding the sheets 4A to 4D.
M, a fixing motor FM as a driving unit for driving the heat roller 37, the pressure roller 38, and the like of the fixing device 35.
And a document feeding motor OM for driving the document feeding unit 10.

FIG. 4 is a block diagram showing a configuration of a control circuit which is a feature of this embodiment, and FIG. 5 is an operation timing chart of the control circuit. First, referring to FIGS. 1 and 4, a feature of this copying machine is that roll bodies 4A1 to 4C are provided.
1 is exchanged, the roll sheet 4 is sent out from the roll bodies 4A1 to 4C1 and the roll sheet 4 is rewound by repeating a series of operations a plurality of times to correct the skew deviation of the front end of the roll sheet and convey it. That is, they are aligned on a line orthogonal to the direction.

More specifically, referring to FIG. 4,
A control circuit 500 for controlling the main motor MM, the paper feeding motor DM, and the fixing motor FM is provided. The control circuit 500 may be a dedicated control circuit or may be configured by a control circuit for controlling the operation of the entire copying machine, for example, a part of a CPU or the like. The control circuit 500 includes a safety switch 501 that outputs an ON signal when the front door 1b is opened, leading edge detection switches 71, 73 and 74 corresponding to the roll sheets 4A to 4C, a registration switch 502, and a rotary blade 82 of the cutter mechanism 80. Home position detection switch 50 for detecting the home position
3. A signal from the transport switch 504 is input. The control circuit 500 controls the rotations of the main motor MM, the paper feeding motor DM, and the fixing motor FM based on these signals, and the rewinding clutch 520.
And the paper feed clutch 521 to control the rewinding / feeding of the supply reels 51, 52 and 53, and the registration clutch 523 to control the rotation / stop of the registration roller 63, and the transport clutch 52.
4 controls the rotation / stop of the transport roller 62, and controls the cutter clutch 525 to control the cutting / stop by the rotary blade 82.

Next, referring to the timing chart shown in FIG. 5, the paper feed motor D controlled by the control circuit 500.
The operations of M, the supply reel 53, the registration roller 63, the conveyance roller 62, and the rotary blade 82 will be described. In the following description, the case where the lower roll sheet 4C is replaced will be described. First, when the setting of the roll body 4C1 is completed and the front door 1b is closed, the front door 1b is closed.
Thus, the safety switch 501 is turned off.

The control circuit 500 rotates the main motor MM, the fixing motor FM, and the paper feed motor DM according to the turning off of the safety switch 501, and the paper feed clutch 521.
Is turned on to rotate the supply reel 53 in the paper feeding direction.
During this paper feeding process, the leading edge 4C2 of the roll sheet 4C is moved to the fourth position.
It is detected by the tip detection switch 74 of the. At a timing after a predetermined time T1, for example, 0.4 seconds has elapsed from the timing of this detection, the sheet feeding clutch 521 is turned off and the rewinding clutch 520 is turned on, so that the roll sheet 4C is turned into a roll body 4C1 by a predetermined length. Rewind.

During this rewinding process, the roll sheet 4C
4C2 passes through the fourth tip detection switch 74. Rewinding clutch 520 at the timing of this passage
Is turned off and the paper feed clutch 521 is turned on to switch to paper feed again. The leading end 4C2 of the roll sheet 4C is stopped at a position where it is slightly rewound from the fourth leading end detection switch 74, and the sheet is fed again.

In this way, a series of operations such as sheet feeding and rewinding as shown in FIG.
Roll sheet 4
The main motor MM, the fixing motor FM, and the paper feed motor DM are stopped and the paper feed clutch 521 is turned on at a timing 0.4 seconds after the leading edge 4C2 of C is detected by the fourth tip detection switch 74. By turning off, the leading end 4C2 of the roll sheet 4C is moved to the fourth
The tip end detection switch 74 is stopped in a state in which it protrudes by a predetermined amount (for example, 30 mm) in the transport direction.

When the front door 1b is closed after the replacement of the roll body 4C1 is completed in this manner, the roll sheet 4 is correspondingly closed.
Since the feeding and rewinding of C are repeated a plurality of times, the leading edge 4C2 of the roll sheet 4C in the oblique state can be automatically and reliably corrected to the straight state. Therefore, it is possible to reliably prevent the occurrence of a jam due to the oblique conveyance of the roll sheet 4C.

Next, when the user presses the tip cut key 530 arranged on the operation unit 100, the main motor MM, the fixing motor FM and the paper feeding motor DM are correspondingly pressed.
Is rotated, and the supply clutch 521 and the registration clutch 52 are rotated.
3 and the transport clutch 524 are turned on, whereby the supply reel 53, the registration roller 63, and the transport roller 62.
Is rotationally driven, and the roll sheet 4C fed from the roll body 4C2 is conveyed to the cutter mechanism 80 side.

The leading edge 4C2 of the conveyed roll sheet 4C
When the paper sheet passes through the registration switch 502, the paper feed clutch 521 and the registration clutch 5 at a timing after a predetermined time T2, for example, 0.38 seconds, from this passage timing
23 and the conveying clutch 524 are turned off to supply the supply reel 53, the registration roller 63, and the conveying roller 62.
Is stopped, and the front end 4C2 of the roll sheet 4C is abutted against the registration roller 63 and is made to stand by (see FIG. 7).

When the cutter clutch 525 is turned on at the timing after the lapse of T2 time (0.38 seconds), the rotary blade 82 is rotated and the home position detection switch 503 detects the home position, the cutter clutch 525 is turned off and the rotary blade 82 is made to stand by at the home position. Further, in response to the detection of the home position, the paper feed clutch 521, the registration clutch 523, and the conveyance clutch 524 are turned on to start the conveyance of the roll sheet 4C again, and during this conveyance, the registration switch 502 is turned on. After a predetermined time T3 has elapsed, the cutter clutch 52
5 is turned on to rotate the rotary blade 82, and roll sheet 4C
Is cut (see FIG. 8).

The above predetermined time T3 is set as follows. First, in the present embodiment, the roll sheet piece that is cut off after cutting is discharged to the outside of the machine through the conveyance path 34 in the same manner as in normal copying. However, in order to discharge in this way, It is necessary that the roll sheet piece has a transport distance between the transport roller 33 and the heat roller 37 and the pressure roller 38 for fixing, for example, a length of 279 mm or more. Here, when the length of the roll sheet piece is set to 279 mm, it suffices to cut the roll sheet 4C by 279 mm from the cutter mechanism 80 when the leading end 4C2 of the roll sheet 4C is conveyed in the conveying direction.
However, when the leading edge 4C2 passes the registration switch 502, the leading edge 4C2 of the roll sheet 4C abuts and is stopped by the registration roller 63 located 50 mm away from the cutter mechanism 80 in the transport direction. Therefore, from the timing when the front end 4C2 passes through the registration switch 502, it is sufficient to carry by 279-50 = 229 mm, and when this is divided by the carrying speed of 80 mm / sec, it becomes 2.86 sec.

When the cutting is completed and the home position detecting switch 503 detects that the rotary blade 82 has reached the home position again, the paper feed clutch 521 and the transport clutch 524 are turned off and the winding is performed accordingly. The return clutch 520 is turned on, and the roll sheet 4C is rewound as shown in FIG. When the leading edge 4C2 of the roll sheet 4C is detected by the fourth leading edge detection switch 74, the rewinding clutch 52 is correspondingly detected.
0 is turned off, the rewinding is stopped, and the cut leading end 4C2 of the roll sheet 4C is set at a predetermined position where the fourth leading end detection switch 74 has rewound a predetermined amount.

On the other hand, the sheet piece 5 separated by cutting
By driving the main motor MM and the fixing motor FM, 50 is transported through the transport path 34 in the same manner as in the case of normal copying, and as shown in FIG. Is discharged to. Since the sheet piece 550 cut in this way is discharged to the outside of the machine, it is possible for the user to save the trouble of removing the sheet piece 550, which is left in the machine as in the conventional case. Further, in the past, when the user performed the next copy without removing the sheet piece, the cutting piece caused a jam, but in the present embodiment, this does not occur.

Incidentally, in the middle of discharging the sheet piece 550,
The rear end of the sheet piece 550 in the conveyance direction is the conveyance switch 504.
In response to the turning off, the sheet feeding motor DM is stopped and the registration clutch 523 is turned off to stop the registration roller 63. Also, when the rear end of the sheet piece 550 is detected by the discharge switch 55, the main motor MM and the fixing motor FM are stopped.

The upper and middle roll sheets 4A and 4B have the same structure as that of this embodiment.
The same effect can be achieved. In addition, various changes can be made within the scope of the present invention.

[0044]

According to the first aspect of the present invention, the feeding and rewinding of the roll sheet are repeated a plurality of times in accordance with the replacement of the roll body, so that the leading end of the roll sheet in an oblique state is automatically In addition, it is possible to surely correct the straight state. Therefore, it is possible to reliably prevent the occurrence of a jam due to the oblique conveyance of the roll sheet.

According to the second aspect of the present invention, when the replacement of the roll body is completed and the door is closed, the above-mentioned oblique state is automatically corrected.

[Brief description of drawings]

FIG. 1 is a simplified cross-sectional view showing an internal configuration of a copying machine to which a roll sheet conveying mechanism according to an embodiment of the present invention is applied.

FIG. 2 is a perspective view showing an external configuration of a copying machine.

FIG. 3 is a perspective view of the copying machine in use.

FIG. 4 is a block diagram showing an electrical configuration of the copying machine.

FIG. 5 is a timing chart showing a series of operations for correcting the skew of the leading edge of the roll sheet and cutting the leading edge, which is performed when the roll body of the roll sheet is replaced.

FIG. 6 is a schematic side view of a main part of a sheet feeding mechanism showing an operation of correcting the skew of the leading edge of the roll sheet.

FIG. 7 is a schematic diagram of a transport path showing a state in which the leading edge of the roll sheet is stopped by a registration roller in the leading edge cutting operation.

FIG. 8 is a schematic view of a conveyance path showing a state in which a roll sheet is cut in a leading edge cutting operation.

FIG. 9 is a schematic view of a conveyance path showing a state in which a cut sheet piece is discharged in a leading edge cutting operation.

[Explanation of symbols]

 4C roll sheet 4C1 roll body 4C2 tip D3 third paper feed path 51, 52, 53 supply reels 71, 73, 74 tip detection switch DM paper feed motor 500 control circuit 501 safety switch

Claims (2)

[Claims] 1. An image forming unit for forming an image by an electrophotographic method and transferring the image onto the roll sheet drawn out from a roll body formed by winding a long sheet, and forming an image on the drawn roll sheet. In a copying machine in which the leading end of the pulled-out roll sheet is set at a predetermined set position in the transport path, the roll body is supported so as to rotate integrally and is rotated in the forward and reverse directions. By doing so, a supply reel capable of sending the roll sheet out of the roll body and rewound to the roll body, a drive system for driving the supply reel so as to be able to rotate forward and backward, and a predetermined unit related to completion of the roll body exchange. A copying machine comprising: control means for operating the drive system so as to reciprocally move the roll sheet forward and backward a plurality of times in response to a signal input. 2. The copying machine according to claim 1, further comprising a door for opening at least a part of the inside of the copying machine for roll replacement, wherein the predetermined signal related to completion of the roll replacement is the door. A copying machine characterized in that it is a signal related to opening and closing.