JPH08188302A - Copying machine - Google Patents

Abstract

PURPOSE: To properly carry a large size copying sheet by rotating a register roller at a circumferential speed slower than that of a carrying roller when the end of the copying sheet being carried on a carrying path is not detected and increasing the speed to a high circumferntial speed when the end is detected. CONSTITUTION: When the end of a copying sheet being carried on a carrying path D4 is not detected, a register roller 39 is rotated at a circumferential speed slower than that of a carrying roller 33 so as to always apply a specified tension to the copying sheet between the carrying roller 33 and the register roller 39. When the end of the copying sheet is detected, the register roller 39 is rotated at a circumferential speed faster by a specified amount than that of the carrying roller 33 so as to make smooth the tension applied to the copying sheet between the carrying roller 33 and the register roller 39. Thus, when an image is formed on a large size copying sheet, especially long copying sheet, skew shifting of the copying sheet is prevented without deformation the image formed thereon.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying machine capable of copying a large-sized original.

[0002]

2. Description of the Related Art An original is illuminated and scanned, an electrostatic latent image is formed on a photosensitive member by reflected light from the original, the electrostatic latent image is visualized as a toner image, and the toner image is formed on a copy sheet. 2. Description of the Related Art Electrophotographic copying machines that are heat-fixed are widely used. As such a copying machine, there is provided a copying machine capable of copying a large-sized original such as Japanese Industrial Standard A line No. 0 (hereinafter referred to as "A0 version").

A copying machine capable of copying a large-sized original document has a reading mechanism capable of reading a large-sized original document, and also has a transport mechanism for transporting a large-sized copy sheet corresponding to the original document. I have it.

[0004]

By the way, when a copy sheet of a large size is conveyed, the copy sheet is slanted during the conveyance, or is copied when it is moved from one conveyance roller to the next conveyance roller. The image may be distorted. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a copying machine which can favorably convey a large size copy sheet.

[0005]

SUMMARY OF THE INVENTION The present invention, in one aspect, comprises an image which comprises a photoreceptor and which is electrophotographically formed on the photoreceptor to be imaged and which is then transferred to a given copy sheet. A forming section, a conveying path for guiding the copy sheet to the image forming section, and a conveying path provided near the image forming section in the conveying path for supplying the copy sheet to the image forming section at a predetermined conveying speed. A roller, a registration roller provided upstream of the position where the transport roller is arranged in the transport path in the transport direction of the copy sheet, and a registration roller viewed in the transport direction of the copy sheet in the transport path. And a sheet end detecting unit provided on the upstream side of the arrangement position, and when the image starts to be transferred to the leading end of the copy sheet in the image forming unit, the trailing end of the copy sheet is the sheet end detecting unit. Than carry In a copying machine for copying a long copy sheet existing on the upstream side in the direction, further, in a state where the sheet edge detecting means does not detect the edge of the copy sheet being conveyed in the conveying path, The registration roller is rotated at a first peripheral speed that is lower than the peripheral speed of the transfer roller by a predetermined peripheral speed so that a predetermined tension is always applied to the copy sheet between the transfer roller and the registration roller, and the sheet edge detecting means is provided. In response to detecting the end portion of the copy sheet being conveyed on the conveyance path, the registration roller is moved to the first position so that the tension applied to the copy sheet between the conveyance roller and the registration roller is smoothly released. Registration driving control means for increasing the peripheral speed from the peripheral speed to the second peripheral speed which is higher than the peripheral speed of the conveying roller by a predetermined speed.

In another aspect of the present invention, a roll sheet drawn out from a roll body formed by winding a long sheet or a cut sheet cut into a predetermined size is used as a copy sheet. In a copying machine, an image forming unit including a photoconductor, an image to be copied is formed on the photoconductor by an electrophotographic method, and the formed image is transferred to a given copy sheet; and a roll sheet is guided to the image forming unit. Of the roll sheet conveyance path, a conveyance roller provided in the vicinity of the front side of the image forming unit of the roll sheet conveyance path, for supplying the sheet to the image forming unit at a predetermined conveyance speed, and cut into a predetermined size. For guiding the cut sheet, the leading end of the path is joined to the roll sheet conveying path so as to guide the cut sheet to the conveying roller. A cut sheet conveyance path having a cut sheet insertion port at the rear end of the path, a registration roller provided in the cut sheet conveyance path, and a registration roller when viewed in the cut sheet conveyance direction in the cut sheet conveyance path. In the state where the sheet edge detecting means provided on the upstream side of the arrangement position and the sheet edge detecting means do not detect the edge of the cut sheet being conveyed in the cut sheet conveying path, the conveying roller and the registration roller In order that a predetermined tension is always applied to the cut sheet between the rollers, the registration roller is moved by a predetermined speed lower than the peripheral speed of the conveying roller.
And was added to the cut sheet between the conveying roller and the registration roller in response to the sheet end detecting means detecting the end of the cut sheet being conveyed through the cut sheet conveying path. Registration drive control means for increasing the speed of the registration roller from a first peripheral speed to a second peripheral speed that is higher than the peripheral speed of the conveying roller by a predetermined speed so that the tension is smoothly released. And

[0007]

According to the present invention, it is possible to prevent the skew of the copy sheet supplied from the registration roller to the transport roller (shift of the copy sheet obliquely with respect to the transport direction). Further, it is possible to eliminate a sudden load change that occurs in the transport roller due to a change in the tension of the copy sheet that occurs when the trailing edge of the copy sheet leaves the registration roller. As a result, it is possible to prevent the image transferred to the copy sheet from being disturbed.

That is, while the copy sheet is being conveyed from the registration roller to the conveying roller, a predetermined tension is applied to prevent the skew feeding. If this tension is still applied, the copy sheet will suddenly lose tension as the trailing edge of the copy sheet leaves the registration rollers. As a result, the load on the transport roller changes, and at that time, the image being transferred onto the copy sheet may be disturbed.

Therefore, when the trailing edge of the copy sheet leaves the registration roller, the peripheral speed of the registration roller is increased so that the tension applied to the copy sheet is smoothly eliminated. As a result, when the trailing edge of the copy sheet leaves the registration roller, the load on the transport roller does not fluctuate, and the formed image is not disturbed.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments 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.

Referring to FIG. 1, upper and lower three rolls of roll sheets 4A, 4B and 4C wound in a roll shape are provided in the lower portion from the center in the height direction inside the main body 1 of the copying machine. Is housed. These roll sheets 4A, 4B and 4C are
They are wound around supply reels 51, 52 and 53, respectively. Examples of the types of the roll sheets 4A, 4B and 4C include plain paper, film and tracing paper. Also, at the center of the copying machine body 1,
For example, a bypass conveyance path D4 for supplying a cut sheet of A0 size to A4 size, which has been cut in advance to a predetermined length, through the manual paper feeding section 30 of the front surface 1a of the copying machine main body 1 is provided.

The upper roll sheet 4A includes the supply reel 51, the paper feed roller 61, and the roll sheet 4A to be conveyed.
A leading edge detecting switch 71 for detecting the leading edge of the sheet, a conveying roller 62, a cutter mechanism 80, a conveying roller 63, a second edge detecting switch 72 for detecting the leading edge of each of the conveyed sheets 4A, 4B, 4C, 4D, And the first transport path D1 to the photosensitive drum 20 through the transport roller 33 in sequence.
Is transported along.

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 that detects the leading edge of the conveyed roll sheet 4B, a feeding roller 62, a cutter mechanism 80, a feeding roller 63, a second leading edge detection switch 72, and a feeding roller 33. Through the
The sheet is conveyed along the second conveying path D2 that reaches the photosensitive drum 20. The path after the carrying roller 62 is common to the first carrying path D1.

The lower roll sheet 4C is a supply reel 5
3, the paper feed roller 65, a fourth leading edge detection switch 74 that detects the leading edge of the conveyed roll sheet 4B, the feeding roller 62, the cutter mechanism 80, the feeding roller 63, the second leading edge detection switch 72, and the feeding roller 33. Through the
The sheet is conveyed along the third conveying path D3 that reaches the photosensitive drum 20. The path after the carrying roller 62 is common to the first carrying path D1.

The bypass conveyance 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 that separates cut sheets (separates one by one) by sliding contact
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 route of the bypass transport route D4 after the second leading edge detection switch 72 is common to the first transport route D1.

The cutter mechanism 80 cuts the roll sheets 4A to 4C between the fixed blade 81 and a long fixed blade 81 extending in a direction orthogonal to the conveying direction of the roll sheets 4A to 4C. And a rotary blade 82 for rotating. The document transport unit 10 has a transport direction of forward direction R1 or reverse direction R.
The original 9 is conveyed by switching to 2. The image forming operation is performed when the document is conveyed in the forward direction R1. When multiple copies are made from the same original,
The document transport unit 10 transports the 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 main body 1, the above-described original document conveying path 41 is formed on the upstream side of the original document conveying section 10 in the forward direction R1 to a position where it is pushed out from the upper surface of the copying machine main body 1.

The above-described document transport unit 10 has a first document edge detection switch 11, a first transport roller 12, a second document edge detection switch 16, a second transport 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
Is turned on, conveyance of the roll sheet 4A, 4B or 4C (hereinafter, the roll sheet 4A, 4B or 4C conveyed for copying is simply referred to as "roll sheet 4") is started, and As a result, the conveyance of the original and the roll sheet 4 are synchronized.

Further, the first document edge detecting 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 this embodiment, the transfer corona discharger 2 from the cutter mechanism 80 is transferred.
4 (transfer position 20b) is longer than the length of the original conveyance path from the first original end detection switch 11 to the original exposure position 44 to the exposure position 20a of the photosensitive drum 20. It is set longer by the length from the transfer position 20b 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.
Detects the trailing edge of the document 9 transported in the reverse direction R2 by switching from on to off when the document 9 is transported in the reverse direction R2. When the leading edge detection switch 16 is turned off, the driving of the transport rollers 12, 14, 15 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.

A light source 17 for illuminating the original surface of the original 9 is fixedly arranged in relation to the transparent plate 13. 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 guided by the SELFOC lens 18 to the surface of the photoconductor drum 20 provided in the substantially central portion of the copying machine main body 1. Photoreceptor drum 2 before being exposed by light from SELFOC lens 18
The surface of 0 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 transport paths D1, D2, D3 or D
The sheet 4 guided from the photosensitive drum 20 to the photosensitive drum 20 is guided to the vicinity of the transfer corona discharger 24 while being in contact with the surface of the photosensitive drum 20, and by the corona discharge of the transfer discharger 24, The toner image on the surface of the drum 20 is transferred to the sheet 4. The sheet 4 on which the toner image is transferred is
It is peeled from the surface of the photoconductor drum 20 by the corona discharge in the peeling corona discharger 25, and is further guided to the fixing device 35 through the conveyance path 34. In this fixing device 35, the toner is fixed on the surface of the sheet 4 by heating and pressing the sheet 4 between the heat roller 37 and the pressure roller 38. The 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.

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.
5 is rotatably supported, and when rotated, guides a sheet that hangs down in front of the guide member 91 and is discharged to the pocket 92 together with the guide member 91 (shown by a chain line in FIG. 1). , And the storage posture held by the stay 95 (shown by the solid line in FIG. 1).

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

FIG. 4 is a block diagram showing a configuration of a control circuit which is a feature of the copying machine according to this embodiment, and FIG. 5 is an operation timing chart of the control circuit. First, referring to FIGS. 1 and 4, one of the features of this copying machine is
The cut sheet conveyed on the bypass conveyance path D4 is improved so as not to be obliquely displaced from the conveyance direction in the bypass conveyance path D4, that is, not to be skewed. The skew feeding prevention of the cut sheet is realized by making the rotational peripheral speed of the registration roller 39 slightly slower than the rotational peripheral speed of the transport roller 33, as described later.

Another feature of this embodiment is that when a cut sheet is conveyed through the bypass conveyance path D4 and the trailing edge of the cut sheet is separated from the registration roller 39, the tension applied to the cut sheet suddenly increases. This is to prevent the load on the transport roller 33 from fluctuating, which causes vibrations and the like on the cut sheet to prevent the toner image transferred from being displaced. In this way, the process for preventing the image misalignment on the cut sheet is also performed by the registration roller 3
It is realized by controlling the rotation peripheral speed of 9.

More specifically, referring to FIG. 4,
A control circuit 220 for controlling the main motor MM and the paper feeding motor DM is provided. This control circuit 2
20 may be a dedicated control circuit or 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 220 is supplied with signals from the fifth tip detection switch 75, the sixth tip detection switch 76, and the second tip detection switch 72. Based on these signals, the control circuit 220 controls the rotations of the main motor MM and the paper feeding motor DM, and also controls the clutches 221, 222, 223 to control the transport roller 33, the registration roller 39, and the separation roller 32. Control rotation / stop.

Next, with reference to the timing chart shown in FIG. 5, the rotation of the photoconductor drum 20, the conveying roller 33, the registration roller 39 and the separation roller 32 controlled by the control circuit 220 will be described. First, the main motor MM is driven and the rotation of the photosensitive drum 20 is started. In this state, the cut sheet is inserted from the manual feed unit 30. Then, the fifth leading edge detection switch 75 is first turned on by the leading edge of the cut sheet.

The control circuit 220 responds to the ON signal of the fifth leading edge detection switch 75 to rotate the paper feeding motor DM and turn on the clutch 223 to cause the separation roller 3 to rotate.
Rotate 2. As a result, the cut sheet inserted from the manual feed unit 30 is taken in and the registration roller 3
Sent to 9. In this case, when there are a plurality of cut sheets inserted from the manual sheet feeding unit 30, one sheet is cut by the separation roller 32.

When the cut sheet is taken in by the separating roller 32, the leading end of the taken cut sheet turns on the sixth leading edge detection switch 76. The ON signal of the sixth tip detection switch 76 is given to the control circuit 220.
In the control circuit 220, the clutch 223 is turned off and the rotation of the separation roller 32 is stopped after a lapse of a predetermined time after receiving the ON signal. The clutch 223 is turned on a predetermined time after the ON signal of the sixth leading edge detection switch 76 is given, so that the leading edge of the cut sheet taken in surely contacts the registration roller 39 and stops. is there. That is, when the cut sheet inserted from the manual feed unit 30 is slightly distorted with respect to the bypass transport path D4, only a part of the front end of the cut sheet hits the registration roller 39. In this state, when the sheet is further fed by the separation roller 32, the distorted cut sheet is corrected so as to be straight to the bypass conveyance path D4. Then, the entire leading edge of the cut sheet is brought into contact with the registration roller 39. That is, the leading ends of the cut sheets are aligned with the line extending in the direction orthogonal to the transport direction.

After that, the clutch 222 is turned on at a predetermined timing, and the registration roller 39 is rotated by the paper feeding motor DM. Due to the rotation of the registration rollers 39, the cut sheet is conveyed along the bypass conveyance path D4, and the leading end of the cut sheet reaches the conveyance roller 33. Since the second leading edge detection switch 72 is provided immediately before the transport roller 33, when the leading edge of the cut sheet reaches the transport roller 33, the second leading edge detection switch 72 is provided.
Turns on.

When the ON signal of the second leading edge detection switch 72 is given, the control circuit 220 turns off the clutch 222 and stops the registration roller 39. In this state,
The timing of the conveyance of the document conveyed by the document conveying section 10 is matched, and the clutch 221 and the clutch 222 are turned on at a predetermined timing corresponding to the conveyance of the document. As a result, the transport roller 33 and the registration roller 3
9 is rotated and the cut sheet is conveyed.

In this case, the peripheral speed of rotation of the conveyance roller 33 and the peripheral speed of rotation of the registration roller 39 are different from each other. Specifically, the rotational peripheral speed of the registration roller 39 is slowed by about 1 to 2% with respect to the rotational peripheral speed of the transport roller 33. As a result, the cut sheet transported by the transport roller and the registration roller 39 is relatively quickly transported by the transport roller 33, and the cut sheet is transported by the registration roller 39
Then it is sent relatively late. As a result, a constant tension is always applied to the cut sheet from the registration roller 39 toward the conveying roller 33. When such tension is applied to the cut sheet conveyed through the conveyance path, the conveyed cut sheet is displaced obliquely with respect to the conveyance path between the registration roller 39 and the conveyance roller 33, that is, the cut sheet. Can be prevented from skewing.

As described above, the copying machine according to this embodiment is a copying machine capable of copying a large-sized original such as A0 size. For example, when copying a document of A0 size, the copy sheet inserted from the manual feed unit 30
It is a large size called A0 version. Even if the leading edge of the large-sized copy sheet is being fed from the transport roller 33 to the photosensitive drum 20, the trailing edge of the large-sized copy sheet still hangs down from the entrance of the manual sheet feeding unit 30. Thereafter, when the conveyance of the copy sheet progresses, the trailing edge of the copy sheet passes through the fifth leading edge detection switch 75 before long.
When the trailing edge of the copy sheet passes the fifth leading edge detecting switch 75, the fifth leading edge detecting switch 75 is turned off.

In the control circuit 220, in response to the off signal of the fifth leading edge detection switch 75, the rotation speed of the paper feeding motor DM is increased. The peripheral speed of rotation of the registration roller 39 is increased by increasing the rotational speed of the paper feeding motor DM. As a specific example, the peripheral speed of rotation of the registration roller 39 is increased by about 5 to 7%. Registration roller 39
Since the rotational peripheral speed is increased not by switching the clutch or the like, but by increasing the rotational speed of the paper feeding motor DM,
The peripheral speed is smoothly increased. Therefore, the transport roller 33
Also, the cut sheet conveyed by the registration roller 39 is not subjected to impact or the like, and the registration roller 3
The tension applied to the cut sheet sent from the conveyance roller 33 from 9 is smoothly removed.

Thereafter, the trailing edge of the cut sheet passes through the sixth leading edge detecting switch 76, and the sixth leading edge detecting switch 7
6 is turned off, and then the trailing edge of the cut sheet separates from the registration roller 39. When the trailing edge of the cut sheet is separated from the registration roller 39, the tension applied to the cut sheet between the registration roller 39 and the transport roller 33 is removed as described above, so that the trailing edge of the cut sheet is At the moment of leaving the registration roller 39,
There is no change in the load of the transport roller 33, and vibration or the like is not applied to the cut sheet.

The registration roller 39 is stopped by turning off the clutch 222 a predetermined time, for example, about 1 second after the sixth leading edge detection switch 76 is turned off. afterwards,
The rear end of the conveyed cut sheet passes through the second front end detection switch 72, and the second front end detection switch 72 is turned off. Then, the trailing edge of the cut sheet is sent out from the conveying roller 33 to the photosensitive drum 20. After the trailing edge of the cut sheet leaves the conveyance roller 33, that is, after a predetermined time after the second detection switch 72 is turned off, the clutch 221 is turned off and the conveyance roller 33 is stopped.

In this embodiment, as described above, the registration rollers 39 provided in the bypass transport path D4 first align the leading ends of the cut sheets inserted in the bypass transport path D4 on a line orthogonal to the transport direction. To be done.
In that state, the conveyance of the cut sheet is started, and a predetermined tension is constantly applied to the cut sheet conveyed from the registration roller 39 to the conveyance roller 33. As a result, the cut sheet being conveyed does not shift obliquely with respect to the conveyance path.

Further, tension is constantly applied to the cut sheet conveyed from the registration roller 39 to the conveyance roller 33, and when the trailing edge of the cut sheet conveyed as it is is separated from the registration roller 39, the cut sheet is cut from the registration roller 39. At the moment the trailing edge of the sheet separates, the tension applied to the cut sheet suddenly disappears.
There is a risk that load fluctuation will occur in No. 3 and vibration or the like will occur in the cut sheet.

Therefore, in this embodiment, when the trailing edge of the conveyed cut sheet is near the registration roller 39, the peripheral speed of rotation of the registration roller 39 is increased and the cut sheet is conveyed from the registration roller 39 to the conveyance roller 33. The tension applied to the cut sheet was smoothly removed. As a result, it is possible to prevent skew and image misalignment with respect to a large-sized cut sheet that is conveyed on the bypass conveyance path D4.

In the copying machine according to this embodiment, a roll sheet is normally used as a copy sheet, and a cut sheet can be manually inserted as a copy sheet from the manual feed section 30. Thus, the configuration of the present invention can be applied to a copying machine in which a cut sheet is always used as a copy sheet.

[0043]

According to the present invention, when an image is formed on a copy sheet having a large size, particularly a long length, skewing of the copy sheet during conveyance can be prevented, and the formed image is distorted. It is possible to provide a copying machine improved so as not to exist.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an internal configuration of a copying machine according to an embodiment of the present invention.

FIG. 2 is a perspective view showing an external configuration of a copying machine according to an embodiment of the present invention.

FIG. 3 is a perspective view showing an external appearance of a copying machine according to an embodiment of the present invention during copying.

FIG. 4 is a block diagram showing a configuration of a control circuit of a conveyance path for conveying cut sheets of the copying machine according to the embodiment of the present invention.

5 is a timing chart showing an operation timing of carrying control of the control circuit in FIG.

[Explanation of symbols]

 20 Photoreceptor Drum 22 Developing Device 24 Corona Discharger for Transfer 30 Manual Feeding Section 32 Separation Roller 33 Conveying Roller 39 Registration Roller 72 Second Tip Detection Switch 75 Fifth Tip Detection Switch 76 Sixth Tip Detection Switch 220 Control Circuits 221, 222, 223 Clutch D4 Bypass transport path MM Main motor DM Paper feed motor

Claims (2)

[Claims] 1. An image forming unit including a photoconductor, which forms an image to be copied on the photoconductor by an electrophotographic method and transfers the formed image to a given copy sheet, and the copy sheet to the image forming unit. A transport path for guiding, a transport roller provided near the image forming unit in the transport path for supplying the copy sheet to the image forming unit at a predetermined transport speed, and a transport of the copy sheet in the transport path. The registration roller provided upstream of the position where the conveyance roller is arranged, and the sheet provided upstream of the position where the registration roller is arranged, as seen in the conveyance direction of the copy sheet in the conveyance path. And a trailing edge of the copy sheet located upstream of the sheet edge detecting means in the conveyance direction when the image is started to be transferred to the leading edge of the copy sheet in the image forming section. Sheet A copying machine that makes a copy against a copy sheet between the transport roller and the registration roller when the sheet edge detecting means does not detect the edge of the copy sheet being transported in the transport path. The registration roller is rotated at a first peripheral speed that is lower than the peripheral speed of the conveying roller by a predetermined speed so that a predetermined tension is applied, and the sheet edge detecting unit conveys the end of the copy sheet being conveyed on the conveying path. In response to the detection of the portion, the registration rollers are moved from the first peripheral speed to the peripheral speed of the transportation rollers so that the tension applied to the copy sheet between the transportation rollers and the registration rollers is smoothly released. A copying machine characterized by further comprising registration drive control means for increasing the speed to a second peripheral speed which is faster by a predetermined speed. 2. A copying machine using a roll sheet drawn from a roll body formed by winding a long sheet or a cut sheet cut to a predetermined size as a copy sheet, including a photoconductor. An image forming section for forming an image to be copied on a photoconductor by an electrophotographic method and transferring the formed image onto a given copy sheet; a roll sheet conveying path for guiding the roll sheet to the image forming section; It is provided in a position near the image forming unit on the sheet conveying path, and is for conveying a sheet to the image forming unit at a predetermined conveying speed, and for guiding a cut sheet cut into a predetermined size. The leading edge of the path is joined to the roll sheet transport path so as to guide the cut sheet to the transport roller, and the trailing edge of the path is cut. A cut sheet transport path having a sheet insertion port, a registration roller provided in the cut sheet transport path, and a cut roller in the cut sheet transport path, which is provided upstream of the registration roller arrangement position when viewed in the cut sheet transport direction. In the state where the end portion of the cut sheet which is being conveyed through the cut sheet conveying path is not detected by the sheet end portion detecting means and the sheet end portion detecting means, the cut sheet between the conveying roller and the registration roller always has a predetermined length. The registration roller is rotated at a first peripheral speed, which is lower than the peripheral speed of the conveying roller by a predetermined speed so that tension is applied, and the sheet edge detecting unit conveys the edge of the cut sheet being conveyed through the cut sheet conveying path. In response to the detection of the portion, the tension applied to the cut sheet between the transport roller and the registration roller is smoothly removed as described above. The Jisutorora, characterized in that the first circumferential speed; and a registration drive control means for increased to a predetermined speed faster second peripheral speed than the peripheral speed of the conveying roller, a copier.