JPH09290941A - Sheet carrying device and sheet treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize a sheet carrying device and a sheet treatment device by setting the distance between a first sheet carrying means and a second sheet carrying means, and the distance between the second sheet carrying means and a third sheet carrying means to be smaller than the length in the carrying direction of a sheet in which the size in the carrying direction is minimum to control the distance between the first sheet carrying means and the third sheet carrying means to a minimum value. SOLUTION: Switch-back carrying means 260, 261 to switch-back carry a first surface printed sheet discharged from an image forming device body 101 after the normal carriage, diagonally carrying means 272-1,273-1 to diagonally carry the switch-back carried sheet and butt it against a carriage reference, and a carry-in/carry-out means 121 to carry the sheet carried by the diagonally carrying means 272-1,273-l to resist roller pairs 122 are arranged on an approximately same plane. The distance between the switch-back carrying means 260, 261 and the carry-in/carry-out means 121 is larger than the length in the carrying direction of' the sheet whose size in the carrying direction is maximum. The distance between the switch-back carrying means 260, 261 and the diagonal carrying means 272-1, 273-1, and the distance between the diagonally carrying means 272-1, 273-1 and the carry-in/carry-out means 121 are smaller than the length in the carrying direction of the sheet whose size in the carrying direction is minimum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet conveying apparatus provided in a sheet processing apparatus such as a printer, a copying machine, a facsimile, a scanner and the like. It should be noted that the sheet processing apparatus referred to here is a generic term for an apparatus having a sheet processing unit that performs predetermined processing (for example, image formation, image reading, etc.) on sheets fed one by one. ing.

[0002]

2. Description of the Related Art Some image forming apparatuses (sheet processing apparatuses) such as printers, copiers, and facsimiles have a single-sided print specification image forming apparatus having only a sheet conveying path for single-sided printing. Some devices are capable of double-sided printing by mounting an optional sheet conveying device for double-sided printing.

Here, the sheet conveying device for double-sided printing, which is detachably attached to the main body of the image forming apparatus, reverses the front and back surfaces of the first-side printed sheet discharged from the main body of the image forming apparatus. Performs the function of transporting into the body. Usually, the reverse of the front and back surfaces of the sheet on which the first side is printed is performed by a switchback transport unit (a pair of rollers capable of rotating in the normal and reverse directions) that changes the transport state from normal transport to switchback transport. The front side and the back side of the sheet on which the first side is printed are reversed during switchback conveyance.

The sheet conveying device for double-sided printing is
In order to print on the second surface of the sheet at the correct position, the sheet also has a function of conveying the sheet in the sheet width direction to the correct position (conveyance reference) into the main body of the image forming apparatus. This function is performed by a restriction unit provided downstream of the switchback transport means. The first-side printed sheet that has been switchback-transported by the switchback transport means is transported into the image forming apparatus main body with one side edge in the width direction abutted by the transport reference of the regulation section by the skew transport transport means. .

In general, the switchback transport means, the oblique transport means, and the carry-in transport means on the image forming apparatus main body side are arranged on substantially the same plane.

[0006]

However, it is difficult to reduce the size of the apparatus when the switchback conveying means, the oblique conveying means and the carry-in conveying means are arranged on substantially the same plane as described above. . Therefore, the present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a sheet conveying apparatus that can be downsized.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a sheet conveying device including at least first, second and second sheet conveying means for nipping a sheet and conveying the sheet in order.

In the present invention, in order to achieve the above object, the distance L between the first sheet conveying means and the third sheet conveying means is set to be larger than the length in the conveying direction of the sheet having the maximum conveying direction size. The distance L1 between the first sheet conveying stage and the second sheet conveying means, and the second sheet conveying means.
The sheet conveying means is characterized in that the distance L2 between the third sheet conveying means is smaller than the length in the sheet conveying direction of which the size in the conveying direction is the smallest.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the overall structure of an image forming apparatus (laser beam printer) equipped with a sheet conveying device for double-sided printing. Further, FIG. 4 shows the configuration of a sheet conveying device for double-sided printing.

The image forming apparatus 100 shown in FIG. 1 has a single-sided printing specification in which a sheet conveying path P1, P3, P4, P5, P6 for single-sided printing is provided in an image forming apparatus main body 101. However, as shown in the figure, double-sided printing is possible by mounting the optional double-sided printing sheet conveying device 200 at a predetermined position of the image forming apparatus main body 101.

Here, the overall configuration of the image forming apparatus 100 will be described along the flow of recording sheets in the single-sided print mode when the optional double-sided printing sheet conveying apparatus 200 is not mounted.

A paper feed cassette 110 is installed at the bottom of the main body 101 of the image forming apparatus.
The recording sheets S stacked and accommodated in the sheet 10 are fed one by one toward the transfer unit.

The recording sheets S stacked and stored in the paper feed cassette 110 are fed out in order from the uppermost sheet by a half-moon shaped feeding roller 120 which makes one rotation counterclockwise in the figure. Then, of the recording sheets S fed by the feeding roller 120, only the uppermost sheet is separated by the separation claw 114.

The recording sheet S fed by the feeding roller 120 passes through the path P1 and reaches the registration roller pair 122 whose rotation is stopped. At this time, the conveying roller pair 121
Conveys the recording sheet S.

The conveying roller pair 121 temporarily stops its rotation when the front end of the recording sheet S hits the nip of the registration roller pair 122 and a predetermined amount of loop is formed on the recording sheet S. By forming this loop, the skewed state of the recording sheet S is corrected.

The recording sheet S after the correction of the skewed state is
In the process unit 140, the photosensitive drum 141 is rotated by the registration roller pair 122 that starts rotating at the timing of aligning the position of the sheet image with the toner image on the photosensitive drum 141 rotating clockwise in the figure.
And the transfer roller 123. This time,
The recording sheet S passes through the path P3. The toner image on the photosensitive drum 141 rotating in the clockwise direction is sequentially transferred to the sheet surface of the recording sheet S sent to the transfer section.

The photosensitive drum 141 rotating in the clockwise direction is irradiated with the laser light L emitted from the laser scanner unit 130. As a result, electrostatic latent images are sequentially formed on the photosensitive drum 141,
The latent image is visualized by toner supplied from a developing device (not shown).

The toner image transferred sheet S conveyed by the photosensitive drum 141 and the transfer roller 123 is sent to the fixing device 150 through the path P4. The transferred toner image is fixed on the sheet surface by being heated and pressed while passing through the nip between the fixing roller 151 and the pressure roller 152.

The recording sheet S on which the fixing process of the toner image has been completed by the fixing device 150 is discharged to the outside of the machine. In the case of the image forming apparatus 100, two kinds of paper discharge modes can be selected. Has become. One is face-down paper ejection, in which the printing surface is ejected downward, and the other is face-up ejection, in which the printing surface is ejected upward.

For example, when face-down sheet discharge is performed, the sheet discharge tray 102 that can be opened and closed in the vertical direction about the support shaft 103 is closed as shown by the solid line, and the flapper 160 passes the path P5. Set it to the position shown by the solid line. By doing so, the recording sheet S conveyed by the paper discharge roller pair 153, 154 passes through the path P5, is discharged outside the machine by the paper discharge roller pair 170, and is formed on the upper surface of the image forming apparatus main body 101. The sheet is stacked on the discharge tray 101a.

When face-up sheet discharge is performed, the discharge tray 102 is opened as shown by the dotted line, and the flapper 160 is set at the position shown by the dotted line to open the path P6. By doing so, the recording sheet S conveyed by the pair of discharge rollers 153 and 154 is discharged to the outside of the machine through the path P6 and the discharge port 104.
The sheets are stacked on the opened sheet ejection tray 102.

The flapper 106, which opens and closes the paths P5 and P6, automatically changes its set position in conjunction with the opening / closing operation of the paper discharge tray 102. That is, when the closed discharge tray 102 is opened to the position shown by the dotted line, the flapper 1 set at the position shown by the solid line is shown.
60 rotates counterclockwise around the support shaft 161 and is set at the position shown by the dotted line. In this case, the flapper 160 is always biased in the clockwise direction by a spring or the like (not shown). Further, when the opened sheet discharge tray 102 is closed as shown by the solid line, the flapper 160 set at the position shown by the dotted line is rotated clockwise by the urging force of the spring or the like and set at the position shown by the solid line. It

When performing double-sided printing with the image forming apparatus 100, as shown in FIG.
The double-sided printing sheet conveying device 200 is mounted at a predetermined position of 1. Here, a part of the sheet conveying apparatus main body 201 is inserted into the space 101b formed between the fixing device 150 of the image forming apparatus main body 101 and the sheet feeding cassette 110 (see FIG. 4). In this way, when a part of the sheet conveying apparatus main body 201 is inserted into the space 101b, the double-sided printing sheet conveying apparatus 200 becomes the image forming apparatus main body 1
01 will be locked automatically. When the double-sided printing conveyance device 200 is pulled out with a constant force, the locked state is released.

When the sheet conveying device 200 for double-sided printing is mounted on the image forming apparatus main body 101, the paper discharge tray 102 must be closed. Therefore,
In the image forming apparatus 100 which is in a state where double-sided printing can be performed, the recording sheets S cannot be discharged onto the discharge tray 102 for face-up discharging, and all the recording sheets S after printing are face-down discharging. The paper is discharged onto the paper discharge tray 101a for paper.

Next, with reference to FIGS. 1 and 4, the structure of the double-sided printing sheet conveying device 200 will be described.

The double-sided printing sheet conveying device 200 is provided with flapper switching means capable of automatically changing the set position of the flapper 160 in the image forming apparatus main body 101. The flapper switching means is a lever member 280 which is rotatable in the up and down directions about the support shaft 281.
And a solenoid 282 whose plunger 282a contracts in the direction of the arrow when the solenoid is turned on. One end (cam follower) 280 a of the lever member 280 has a cam member 162 fixed on the support shaft 161 of the flapper 160.
Is in contact with Also, the other end 280 of the lever member 280
The link b is linked to the tip of the plunger 282a by a link shaft 283.

When the solenoid 28 is turned on and the plunger 282a is contracted, the lever member 280 rotates in the clockwise direction around the support shaft 281 and the cam follower 280 is rotated.
a presses the cam member 162. As a result, the cam member 162 rotates counterclockwise, and the flapper 160 is set to the position where the path P6 is opened, as shown in FIG. When performing double-sided printing, the flapper 160 is first set at this position so that the first-side printed sheet S can be inserted into the full-sided double-sided printing sheet conveying device 200.

When the plunger 282a is extended with the solenoid off, the lever member 280 rotates counterclockwise about the support shaft 281 and the cam follower 28 is rotated.
The pressing force of 0a is released. Thereby, the cam member 16
2 rotates in the clockwise direction, and the flapper 160 is set to the position where the path P5 is opened, as shown by the solid line in FIG. The flapper 160 is set at this position so that the second-side printed sheet S can pass through the path P5 after the first-side printed sheet S passes through the path P6 during double-sided printing. Also, the flapper 160 is always set at this position during single-sided printing.

In the sheet conveying apparatus 200 for double-sided printing, the front and back surfaces of the first-side printed sheet S discharged from the discharge port 104 of the image forming apparatus main body 101 are reversed and conveyed into the image forming apparatus main body 101. Switchback transport means (first sheet transport means) 260, 261
Is provided. This switchback transport means 26
In Nos. 0 and 261, the front surface and the back surface are reversed by normally carrying the first-side printed sheet S and then carrying it by switchback. Here, 260 is a conveyance roller that is driven by the motor M1 and can rotate in the forward and reverse directions, and 261 is a conveyance roller that contacts the conveyance roller 260 and is driven to rotate. The sheet S on which the first surface is printed is conveyed by the conveyance roller 260 and the conveyance roller 261. It should be noted that the conveying roller 261 is moved by the urging force of the spring 262 to the conveying roller 26.
0 is contacted with a predetermined pressure. Further, the conveyance roller 260 is attached to the sheet conveyance device main body 201 side, and the conveyance roller 261 is attached to the openable / closable cover 212 side.

The first-side printed sheet S discharged from the discharge port 104 of the image forming apparatus main body 101 passes through the path P7.
After passing through, the sheet reaches the conveying roller 260, and the leading edge of the sheet enters the nip between the conveying roller 260 and the conveying roller 261.

A reversing flapper 251 is installed upstream of the conveying roller 260. This flapper 251
Normally closes the downstream portion of the path P7 as shown in FIG. In this case, the flapper 251 rotates clockwise around the support shaft 250 due to its own weight and contacts the positioning member 215 provided on the cover member 212. Then, when the side surface 251a is pressed against the front end of the first-side printed sheet S moving toward the downstream side, as shown in FIG. 7 is opened and the sheet S is passed through.

As shown in FIG. 5, when the flapper 251 opens the path 7, the light blocking member 252 interlocked with the rotation of the flapper 251 is on the optical path of the photo interrupter 240 (between the light emitting portion 241 and the light receiving portion 242). Then, the photo interrupter 240 is turned on. When the photo interrupter 240 is turned on, it can be detected that the first-side printed sheet S is passing through the flapper 251 portion. Further, when the flapper 251 changes from the state where the path P7 is opened to the state where the path P7 is closed, the light blocking member 2
Reference numeral 52 blocks the optical path of the photo interrupter 240. As a result, the photo interrupter 240 is turned off. When the photo interrupter 240 is turned off, it can be detected that the trailing edge of the first-side printed sheet S has passed the flapper 251.

The transport roller 260 rotates counterclockwise to normally transport the sheet S on which the first side is printed.
The first-side printed sheet S moving downstream due to this conveyance enters into the path P8. In this case, the transport speed of the transport roller 260 is the same as the transport speed of the paper discharge roller pair 153, 154. FIG. 5 shows the first-side printed sheet S that is normally conveyed by the conveying roller 260.

Immediately after the trailing edge of the sheet passes through the flapper 251, the photointerrupter 240 is turned off at this point, and the flapper 251 closes the path P7. The sheet S on which the surface has been printed is switched back. FIG. 6 shows the first-side printed sheet S on which switchback conveyance is started. The first-side printed sheet S that has been switched back enters the reversing path P9 while being guided by the side surface 251b of the flapper 251 that closes the path P7, and proceeds downstream. By passing through this path P9, the front and back surfaces of the first-side printed sheet S are reversed.

The first-side printed sheet S that has switched back and passed through the path P9 passes through the path P10 in the main body 271 of the regulating device 270 (detected by the photo interrupter 290) as shown in FIGS. Subsequently, as shown in FIG. 9 and FIG. 10, the path P2 is passed, the path P1 is merged, and a pair of carry-in and carry rollers (third sheet carrying means) 121
Is sent to the pair of registration rollers 122 whose rotation is stopped. Hereinafter, the first-side printed sheet S whose front and back surfaces are reversed by the double-sided printing sheet conveying device 200 is
After being conveyed in the same manner as when printing on the first side, and after passing through the steps of printing on the second side and fixing the toner image, the sheet is discharged onto the discharge tray 101a outside the apparatus by the discharge roller pair 170.

The structure and function of the regulating device 270 will be described with reference to FIGS.

The regulating device 270 is for moving the first-side printed sheet S moving in the path P9 along the one-sided conveyance reference. While the first-side printed sheet S is moving in the path P10, the entire one side end in the width direction (front side end in FIG. 2) comes into contact with the conveyance reference surface. Then, the sheet S is an oblique feeding conveyance means (second and fourth sheet conveying means installed upstream and downstream of the main body 271 and includes a conveyance roller 272-1, an oblique feed roller 273-1, and a conveyance roller 272. -2 and skew feeding 273-2).

In the path P10, a vertical guide surface (one side conveyance reference surface) 271c and an inclined guide surface 271f are formed.

The sheet S that has passed the path P9 has a guide surface 2
While being guided by the guide 71f, it enters the path P10, and the one side end in the width direction is guided to the guide surface 2371 by the above-mentioned oblique transporting means.
c.

Next, the structure of the skew feeding and conveying means for skew feeding and feeding the first-side printed sheet S moving in the path P10 will be described.

The skew feeding and conveying means is constituted by the conveying rollers 272-1 and 272-1.
272-2 and skew feed rollers 273-1 and 273-2. The transport rollers 271-1 and 271-2 are roller shafts 272 that are oriented in a direction orthogonal to the sheet transport direction.
It is fixed on a and 272b. Roller shaft 272a,
The 272b is rotatably attached to the main body 271 via bearings 275 and 276. Both roller shafts 272
The a and 272b are connected by an endless belt 279 wound around pulleys 277 and 278. The drive of the motor M2 drives the roller shaft 27 through the gears 281 and 280.
2a and 272b, the transport rollers 272-
1, 272-2 rotate clockwise in FIG.

The skew feeding rollers 273-1 and 273-2 are in contact with the conveying rollers 272-1 and 272-2 with a predetermined pressure. These rollers 273-1 and 273-2 are the main body 2
It is supported by a leaf spring 274 attached to 71 and is biased by the leaf spring 274. As a result, the rollers 273-1 and 273-2 move to the rollers 272-1 and 272-1.
It rotates following the rotation of 272-2. Also, roller 273-
The nip lines of 1,273-2 are rollers 272-1,272
-It is in a state of being inclined with respect to the nip line. As a result, the rollers 272-1 and 272-2 and the roller 27 are
3-1 sandwiched by 3-1 and 273-2 and conveyed
The surface-printed sheet S is brought closer to the guide surface 271c.

Here, referring to FIG. 3, switchback conveying means 260, 261 arranged on substantially the same plane.
The positional relationship between the skew feeding and conveying means 272-1 and 273-1 and the carry-in and conveying means 121 will be described.

The distance L between the switchback transport means 260, 261 and the carry-in transport means 121 is larger than the transport direction length L _{max of the} maximum size SL (LGL) in the transport direction. In addition, the switchback transport means 2
60, 261, the distance L1 between the oblique conveying means 272-1, 273-1, and the oblique conveying means 271-1, 273-
The distance L2 between 1 and the carry-in / convey unit 121 is the length L _min in the conveyance direction of the sheet SS (SB) having the smallest size in the conveyance direction.
Is smaller than. Oblique transport means 272-1, 272-1
Between the 73-1 and the carry-in / conveying means 121, another skew feeding / conveying means 272-2, 273-2 is arranged.

The length of the LGL size sheet in the carrying direction is about 355.6 mm, and the length of the B5 size sheet in the carrying direction is 257 mm.

As shown in FIG. 8, the sheet S that has been switchback-transported by the switchback transporting means 260, 261 is upstream of the oblique transporting means 272-1, 273.
After being pinched by -1, it will be conveyed obliquely,
After the trailing edge of the sheet passes through the nip of the switchback transporting means 260, 261, it becomes easy to move in the sheet width direction, so that the skew feeding transport is performed at high speed. In this case, the distance L1 should be as long as possible.

As shown in FIG. 9, the preceding sheet S which has completed the conveyance reference adjustment in the regulation device 270 is detected by the photo interrupter 290 at a timing, and the switchback conveyance means 260, 261 and the carry-in conveyance means 121.
Temporarily stop moving between. In this way, the succeeding sheet can be carried into the path P7, so that the throughput does not decrease.

As shown in FIG. 10, the sheet S conveyed by the two skew feeding and conveying means 272-1, 273-1 and 272-2, 273-2 is conveyed by two skew feeding until it reaches the carry-in and conveying means 121. Since it is sandwiched by the conveying means, it does not skew even if the path P2 has a curved portion.

As shown in FIG. 11, when a plurality of wear preventing metal rods 300 are provided on the guide surface 271c, the plurality of metal rods 300 are abutted against the plurality of metal rods 300 until the sheet S is nipped by the carry-in / convey unit 121. It is preferable that they are in contact with each other.

The path P7 is a guide member 224, 213, 2
01a, the path P8 is formed by the guide member 21.
4, 201c, 201d, and the path P9 is formed by guide members 201a, 201b. The guide member 224 is attached to the cover member 220. The guide members 213 and 214 are the cover members 21.
It is attached to 2. Guide members 201a, 201
b and 201c are attached to the main body 201. The guide member 201d is a bottom plate of the main body 201.

In the present specification, the first sheet conveying means, the second sheet conveying means, and the third sheet conveying means are the sheet conveying apparatus 200 for double-sided printing and the image forming apparatus (sheet processing apparatus) 100. Although the sheet conveying device extending over the sheet conveying device has been described, the sheet conveying device in which the first sheet conveying device, the second sheet conveying device, and the third sheet conveying device exist only on the image forming device (sheet processing device) 100 side. Also, the present invention is applicable.

[0053]

As described above, in the sheet conveying apparatus of the present invention, the distance between the first sheet conveying means and the third sheet conveying means is determined by the length in the conveying direction of the sheet having the largest conveying direction size. Also, the distance between the first sheet conveying unit and the second sheet conveying unit and the distance between the second sheet conveying unit and the third sheet conveying unit are set to the minimum sheet size in the conveying direction. Since the length is smaller than the length in the conveyance direction, the distance between the first sheet conveying means and the third sheet conveying means can be suppressed to the minimum length, and the apparatus can be downsized.

Further, by stopping the movement of the preceding sheet between the first sheet conveying means and the second sheet conveying means, the succeeding sheet can be brought closer to the first sheet conveying means, and the apparatus is downsized. Does not reduce the throughput.

[Brief description of drawings]

FIG. 1 The present invention is applied (laser beam printer).
FIG.

FIG. 2 is a partially cutaway plan view showing a configuration of a sheet conveying device for double-sided printing.

FIG. 3 is a side view showing a positional relationship between a switchback transport unit, a skew transport unit, and a carry-in transport unit.

FIG. 4 is a vertical cross-sectional side view showing a state in which the first-side printed sheet enters the sheet conveying device for double-sided printing.

FIG. 5 is a vertical cross-sectional side view showing a state in which the sheet on which the first side is printed moves in the sheet conveying apparatus for double-sided printing.

FIG. 6 is a vertical cross-sectional side view showing a state in which a sheet on which printing has been performed on the first side moves in the sheet conveying apparatus for double-sided printing.

FIG. 7 is a vertical cross-sectional side view showing a state in which the sheet on which the first side is printed moves in the sheet conveying apparatus for double-sided printing.

FIG. 8 is a vertical cross-sectional side view showing a state in which the sheet on which the first side is printed moves in the sheet conveying apparatus for double-sided printing.

FIG. 9 is a vertical cross-sectional side view showing a state in which the sheet on which the first side is printed moves in the sheet conveying apparatus for double-sided printing.

FIG. 10 is a vertical cross-sectional side view showing a state in which the sheet on which the first side is printed moves in the sheet conveying apparatus for double-sided printing.

FIG. 11 is a plan view showing an arrangement relationship of wear preventing metal rods.

[Description of sign]

121 carry-in / conveying means (third sheet conveying device) 123 transfer drum (sheet processing means) 141 photosensitive drum (sheet processing means) 260,261 switchback conveying means (first sheet conveying device) 272-1, 272-2 Oblique feeding / conveying means (second sheet conveying means) 272-2, 273-2 Oblique feeding / conveying means (fourth sheet conveying means) 290 Photo interrupter (sheet detecting means) L, L1, L2 Distances P1 to P10 paths ( Conveyance path) S sheet SL Sheet with the largest size in the conveying direction SS Sheet with the smallest size in the conveying direction

Claims (7)

[Claims] 1. A sheet conveying device comprising at least first, second and third sheet conveying means for nipping and sequentially conveying a sheet, wherein the first sheet conveying means and the third sheet conveying means are provided. The distance L between the means is set larger than the length in the carrying direction of the sheet having the largest carrying direction size, and the distance L1 between the first sheet carrying means and the second sheet carrying means, and the second sheet carrying means.
The sheet conveying apparatus, wherein the distance L2 between the sheet conveying means and the third sheet conveying means is smaller than the length in the conveying direction of the sheet having the smallest conveying direction size. 2. The sheet conveying device according to claim 1, wherein the first, second, and third sheet conveying units are roller pairs. 3. The first sheet conveying means is a means for inverting the front and back surfaces of the sheet, and the second sheet conveying means is a means for obliquely feeding the sheet and abutting it against a conveyance reference. The sheet conveying device according to claim 1, wherein the third sheet conveying means is a means for feeding a sheet to a predetermined position. 4. A fourth sheet conveying means for obliquely feeding the sheet and abutting it on a conveyance reference is arranged between the second sheet conveying means and the third sheet conveying means. The sheet conveying device according to claim 3. 5. The sheet detecting means for providing a timing for stopping a sheet between the first sheet conveying means and the second sheet conveying means, according to claim 1. Sheet transport device. 6. A sheet comprising: the sheet conveying device according to claim 1; and a sheet processing unit that performs a predetermined process on the sheet conveyed by the sheet conveying device. Processing equipment. 7. A sheet processing apparatus comprising the sheet carrying device according to claim 1 on a sheet carrying path connecting an upstream side and a downstream side of a sheet processing means.