JP3382455B2 - Sheet conveying device and sheet processing device - Google Patents

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 (sheet conveying device).

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 unit is transported in the image forming apparatus main body with one side edge in the width direction abutted against the transport reference of the regulation unit.

The conventional restricting section is adapted to change the position in the sheet width direction according to the width size of the sheet conveyed by switchback. As a result, the conveyance reference is set at a position corresponding to the width size of the sheet.

[0006]

However, in the case of the above-mentioned conventional example, there is a problem that the apparatus becomes complicated and the cost becomes high because a means for moving the regulating portion in the sheet width direction is required.

Therefore, the present invention has been made in view of the above-mentioned circumstances, and even if the regulating portion is fixed at a fixed position without moving in the sheet width direction, sheets having different width sizes are used as the conveyance reference. It is an object of the present invention to provide a sheet conveying device capable of conveying in accordance with the above.

[0008]

According to the present invention, there is provided a sheet carrying means having a carrying roller for carrying a sheet, and a regulating section for setting a sheet carrying reference position at a downstream portion of the sheet carrying means. The regulating unit relates to a sheet conveying apparatus having a guide surface fixed at a position that regulates the position of one side end of the sheet to a conveyance reference position, and an oblique feeding roller that brings the sheet to the guide surface.

In order to achieve the above-mentioned object, the present invention provides a first mode in which a sheet is conveyed by the sheet conveying means toward the regulating portion without substantially changing the position in the width direction of the sheet, and the conveyance. A second mode in which the roller is moved in the width direction of the sheet to move the sheet by a predetermined amount to the conveyance reference position side of the regulation unit by the sheet conveyance unit and convey the sheet toward the regulation unit;
It is characterized in that the first mode or the second mode is selected according to the width size of the sheet.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

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

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 image forming apparatus main body 101.
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 sequentially fed out from the uppermost sheet by a half-moon shaped feeding roller 120 that 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 reaches the registration roller pair 122 whose rotation is stopped through the path P1. At this time, the conveying roller pair 121
Conveys the recording sheet S.

The conveying roller pair 121 temporarily stops its rotation when the leading 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 a 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 which has been subjected to the fixing process of the toner image 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 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 that opens and closes the paths P5 and P6 automatically changes its set position in conjunction with the opening and 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 sheet conveying device 200 for double-sided printing of the present invention is mounted at a predetermined position of 1. Here, the sheet conveying apparatus main body 20
1 is a part of the fixing device 150 of the image forming apparatus main body 101.
1 formed between the sheet and the sheet cassette 110
01b (see FIG. 4). As described above, 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 is automatically locked with respect to the image forming apparatus main body 101. When the double-sided printing conveyance device 200 is pulled out with a constant force, the locked state is released.

When the sheet conveying apparatus 200 for double-sided printing according to the present invention 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 that is in a state where double-sided printing is possible, the recording sheet S cannot be discharged onto the discharge tray 102 for face-up discharge, and all the recording sheets S after printing are face down. The paper is discharged onto the paper discharge tray 101a for paper discharge.

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

The sheet conveying apparatus 200 for double-sided printing 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 extends 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 turned and conveyed into the image forming apparatus main body 101. Switchback conveying means (sheet conveying means) 260, 261 for the above. This switchback transport means 260, 261
After the first-side printed sheet S is normally conveyed, it is switched back to be reversed so that the front and back surfaces are reversed. 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 the conveyance roller 26.
It is a transport roller that comes into contact with 0 and rotates following it. The sheet S on which the first surface is printed is conveyed by the conveyance roller 260 and the conveyance roller 261. The transport roller 261
Is in contact with the conveying roller 260 with a predetermined pressure by the urging force of the spring 262. Further, the conveyance roller 260 is attached to the sheet conveyance device body 201 side, and the conveyance roller 2
Reference numeral 61 is attached to the opening / closing 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.

In addition, in the upstream portion of the conveying roller 260,
An inversion flapper 251 is installed. The 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. And the first moving downstream
When the side surface 251a is pressed against the front end of the surface-printed sheet S, as shown in FIG. 5, it rotates counterclockwise around the support shaft 250 to open the path 7 and allow the sheet S to pass 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 carrying roller 260 rotates counterclockwise and normally carries the first-side printed sheet S. 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 transport roller 260
2 shows the first-side printed sheet S that is normally conveyed by.

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 transport roller 260 rotates clockwise and the first 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 restricting device (restricting portion) 270 (detected by the photo interrupter 290) as shown in FIG. Then, it passes through the path P2, merges with the path P1, and is sent to the registration roller pair 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 conveyed in the same manner as during the first-side printing, and is printed on the second side and the toner image fixing process is performed. After the above step, the sheet is discharged onto the sheet discharge tray 101a outside the apparatus by the sheet discharge roller pair 170.

FIG. 2 shows a detailed structure of the switchback conveying means (conveying roller 260, conveying roller 261). 2 is a front view seen from the left side of FIG.

The conveying roller 260 is composed of a plurality of rollers 260-1 to 260-1 arranged at predetermined intervals in the sheet width direction.
It consists of 260-4. Each of the rollers 260-1 to 260-1
The rollers 261-1 to 261-4 are provided with springs 262 in 260-4.
The contact points are urged by -1 to 262-4. Roll 26
The shafts 261 a of 1-1 to 261-4 are the cover members 212.
Is rotatably attached to (fixed position) support plates 263 and 264.

The shaft 260 of the rollers 260-1 to 260-4
a is a bearing 266 with respect to the support members 265a and 265b.
It is mounted so as to be rotatable and slidable via a and 266b. The drive of the motor M1 is transmitted to the shaft 260a via the helical gear 267. The helical gear 267 is non-rotatably fitted to the shaft 260a, and cannot be slid on the shaft 260a by the restricting members 268a and 268b.

FIG. 2 shows the roller 260-in the normal carrying operation.
The set positions of 1-260-4 are shown. At this time, the rollers 260-1 to 260-4 are connected to the rollers 261-1 to 261.
-4, and the regulating member 268c is located at a position separated from the bearing 266b by a distance H. This position is the home position of the rollers 260-1 to 260-4.

Next, the operation and function of the switchback conveying means 260, 261 will be described with reference to FIGS.

Here, it is assumed that the image forming apparatus 100 uses two types of width-size sheets (LTR, A4).

Switchback transport means 260, 261
Operates in the order shown in FIGS. 8 to 12 when an LTR sheet having a large width is conveyed.

As shown in FIG. 8, when the tapered portion of the sheet S comes into contact with the nip portion, the sheet S is nipped and conveyed by the switchback conveying means 260, 261 as shown in FIG.
At this time, the roller shaft 260a moves in the arrow direction (leftward direction) by the action of the twist angle of the gear 267. Therefore,
The sheet S nipped by the switchback conveying means 260, 261 also moves in the arrow direction (left direction) while passing through the path P.
8 is transported.

As shown in FIG. 10, the rear end of the sheet S is detected by the photo interrupter 240, and the motor M
The roller shaft 260a waits in a state in which the regulating member 268c is in contact with the bearing 266b before the driving of the No. 1 is stopped.
At this time, the transport roller 260 moves the distance H from the home position together with the sheet S transported into the path P8.

When the drive of the motor M1 rotates in the reverse direction and the sheet S is switchback conveyed as shown in FIG. 11, the roller shaft 260a moves in the direction of the arrow (rightward) due to the action of the twist angle of the gear 267. Direction). Further, in the roller shaft 260a, the leading end of the sheet S that is switchback-conveyed is the re-feeding means 272-1 on the upstream side of the regulating device 270.
By the time it is sandwiched by 273-1, the restriction member 268b is in contact with the bearing 266a as shown in FIG. At this time, the transport roller 260 is at the same position as the home position (FIG. 2) together with the sheet S transported into the path P9. That is, the position in the width direction when discharged from the image forming apparatus main body 101 on the upstream side and the position in the width direction when entering the re-feeding unit on the downstream side are almost the same. This is the first mode.

Switchback transport means 260, 261
When conveying an A4 sheet with a small width,
It operates in the order of FIG. 13 to FIG.

As shown in FIG. 13, at the end of the switchback conveyance, before the next sheet S having the first surface printed thereon comes into contact with the nip portion of the switchback conveyance means 260, 261, the conveyance roller 260 is preliminarily changed during the switchback conveyance. Rotates in the counterclockwise direction, which is the opposite rotation direction, and stands by with the restriction member 268c in contact with the bearing 266b.

As shown in FIG. 14, the front end portion of the sheet S on which the first surface is printed has the switchback conveying means 260, 2.
When the sheet S comes into contact with the nip portion 61, the sheet S is nipped and conveyed by the switchback conveying means 260 and 261 as shown in FIG. However, since the regulating member 268c is already in contact with the bearing 266b, the conveying roller 260 cannot move any further, and the sheet S advances straight and is conveyed into the path P18 as shown in FIG.

As shown in FIG. 17, when the transport roller 260 is rotated in the reverse direction and the sheet S is switchback-transported, the transport roller 260, together with the sandwiched sheet S, gear 26.
By the action of the helix angle of 7, it moves in the arrow direction (to the right). Therefore, as shown in FIG. 18, the sheet S has a sheet front end on the upstream side of the regulating device 270.
It moves a distance H until it is sandwiched by the Nos. 1 and 273-1. That is, the position in the width direction on the side of the regulation device 270 that comes into contact with the conveyance reference is a distance H between when the image forming device main body 101 on the upstream side is discharged and when it enters the re-feeding device on the downstream side.
Only different, is conveyed to a position where the distance H closer only the transport side as compared with the first mode described above. This is the second mode.

The image forming apparatus main body 101 is usually provided with detection means for detecting the size of the sheet S used. The double-sided printing sheet conveying device 200 receives the signal from the size detecting means and selects the first mode for the LTR size, and the second mode for the A4 size.
Select the mode of. Since the distance H is {216 (LTR width) -210 (A4 width)} / 2 = 3, the distance H is set to be about 3 mm.

As shown in FIG. 19, when the sheet SA (LTR size) having a large width is conveyed, it is in the first mode, so that the sheet is discharged from the image forming apparatus main body 101 at substantially the same position. Then, it is carried into the path P10. Then, the sheet SA is conveyed while the position in the width direction of the sheet (direction orthogonal to the sheet conveyance direction) is regulated by the conveyance reference (guide surface 271c) of the regulation device 270.

As shown in FIG. 20, when the sheet SB (A4 size) having a small width size is conveyed, the second mode is set, so that the regulation device is about 3 mm from the position where the sheet is discharged from the image forming apparatus main body 101. It is carried into the path P10 at a position (the same position as the LTR size) approaching the transport reference of 270. In this case, the movement of the sheet SB in the width direction is
It is preferable that the leading end of the sheet is finished before being pinched by the re-feeding means on the upstream side of the regulating device 270.

As described above, even if the width size of the sheet is different and the position where the sheet is discharged from the image forming apparatus main body 101 is different, the position in the sheet width direction on the side contacting the conveyance reference of the regulating device 270 is always the same. In this state, the sheet can be conveyed to the regulation device 270.

The sheet S moving in the regulating device 270
When the trailing edge of the sheet S leaves the nip of the switchback conveying means 260, 261, and the leading edge of the sheet S reaches the photo interrupter 290, the driving of the motors M1 and M2 is temporarily stopped. Then, after a predetermined time has passed and the timing is taken, only the motor M2 is driven to convey the sheet S into the image forming apparatus main body 101. On the other hand, the motor M1 switches the sheet S to the switchback transport unit 2 in case the next sheet S is transported from the image forming apparatus 101.
It waits for driving 60 and 261 and carrying again.

Since the conveying speed of the re-feeding means of the regulating device 270 and the conveying speed of the conveying means on the downstream side thereof are set to be substantially equal, the regulating device 270 regulates the position in the width direction. The sheet S is conveyed into the path P2 of the image forming apparatus main body 101 from the rear end side with the second surface facing upward.

In the case of this example, the sheet SB having a small width size
The position of the second side sheet in the width direction is aligned with the position of the sheet SA having a large width size by the regulating device 270. Therefore, the print position of the second side is displaced, and the left end margin is widened by about 3 mm. In order to eliminate such a case, in the case of the sheet SB having a small width size, by correcting the laser irradiation position on the second surface by that amount,
An image is recorded and formed at the same position as the first surface.

Although the case where two types of width size sheets (LTR, A4) are used has been described here,
When two or more types of width size sheets are used, if a detection unit for detecting the position of the conveyance roller 260 in the sheet width direction is provided, the conveyance roller 260 can be controlled by controlling the rotation or the number of rotations of the motor M1. The stop position (home position) of can be finely controlled. That is, it can be applied to sheets of various width sizes.

Here, the configuration 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 that has moved 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. 3) comes into contact with the conveyance reference surface. Then, the sheet S is re-feeding means (conveying rollers 272) installed upstream and downstream of the main body 271.
−1 and the skew feed roller 273-1, and the transport roller 272-2 and the skew feed 273-2) are carried into the image forming apparatus main body 101.

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

The sheet SA passing through the path P9 enters the path P10 while being guided by the guide surface 271f, and one side end in the width direction is guided to the guide surface 2371 by the re-feeding means.
It moves while being in contact with c.

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

The re-feeding means is composed of the transport rollers 272-1 and 272-1.
72-2 and oblique feeding 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 oblique 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 printed sheet S has guide surfaces 271c and 271d.
You can get closer to the direction.

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.

[0068]

As described above, in the sheet conveying apparatus of the present invention, when the sheet conveying means conveys a sheet having a specific width size (a width size equal to or smaller than the maximum width size), the sheet is controlled by the regulating unit. Since the sheet is conveyed while being moved to the conveyance reference position side by a predetermined amount, even if the regulation portion is fixed at a predetermined position in the sheet width direction, the width direction of sheets of various width sizes is correct as the conveyance reference of the regulation portion. You can hit it in the state.

Therefore, it is only necessary for the sheet conveying means to move the sheet in the sheet width direction, and it is not necessary to move the regulating portion in the sheet width direction. For this reason, the device is simplified and the cost is reduced because the regulation unit is not provided with a moving unit.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view showing the overall configuration of an image forming apparatus (laser beam printer) equipped with a double-sided printing sheet conveying device of the present invention.

FIG. 2 is a front view showing a configuration of a switchback means in the sheet conveying apparatus for double-sided printing.

FIG. 3 is a partially cutaway plan view showing a configuration of a regulating device in the sheet conveying device for double-sided printing.

FIG. 4 is a vertical cross-sectional side view showing the configuration of a sheet conveying device for double-sided printing according to the present invention.

FIG. 5 is a vertical cross-sectional side view showing a state in which a sheet having finished printing on the first side thereof moves in the double-sided printing sheet conveying device.

FIG. 6 is a vertical cross-sectional front view for explaining the configuration, operation and function of the final transport path unit.

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

8A and 8B are a front view (FIG. 8A) and a vertical sectional side view (FIG. 8B) for explaining the operation when the switchback conveying unit conveys an LTR size sheet.

9A and 9B are a front view (FIG. 9A) and a vertical cross-sectional side view (FIG. 9B) for explaining the operation when the switchback transport unit transports an LTR size sheet.

FIG. 10 is a front view for explaining the operation when the switchback transport means transports an LTR size sheet (FIG. 10 (a)).
) And a vertical side view (Fig. 10 (b)).

FIG. 11 is a front view for explaining the operation when the switchback transport unit transports an LTR size sheet (FIG. 11A).
) And a vertical side view (Fig. 11 (b)).

FIG. 12 is a front view for explaining the operation when the switchback transport unit transports an LTR size sheet (FIG. 12 (a)).
) And a vertical side view (Fig. 12 (b)).

FIG. 13 is a front view for explaining the operation when the switchback conveying means conveys an A4 size sheet (FIG. 13 (a)).
And a vertical side view (Fig. 13 (b)).

FIG. 14 is a front view for explaining the operation when the switchback conveying means conveys an A4 size sheet (FIG. 14 (a)).
And a vertical side view (Fig. 14 (b)).

FIG. 15 is a front view for explaining the operation when the switchback conveying means conveys an A4 size sheet (FIG. 15 (a)).
And a vertical side view (Fig. 15 (b)).

FIG. 16 is a front view for explaining the operation when the switchback transport means transports an A4 size sheet (FIG. 16 (a)).
And a vertical side view (Fig. 16 (b)).

FIG. 17 is a front view for explaining the operation when the switchback transport means transports an A4 size sheet (FIG. 17 (a)).
And a vertical side view (Fig. 17 (b)).

FIG. 18 is a front view (FIG. 18 (a)) for explaining the operation when the switchback conveying means conveys an A4 size sheet.
And a vertical side view (Fig. 18 (b)).

FIG. 19 is a plan view showing sheet width direction positions of LTR size sheets before and after switchback conveyance by the switchback conveyance means.

FIG. 20 is a plan view showing positions in the sheet width direction of an A4 size sheet before and after being switchback-conveyed by the switchback conveying means.

[Explanation of symbols]

Reference Signs List 100 image forming apparatus (sheet processing apparatus) 123 transfer roller (sheet processing means) 141 photosensitive drum (sheet processing means) 200 sheet conveying apparatus for double-sided printing (sheet conveying apparatus) 260 conveying rollers (switchback conveying means)
Sheet conveying means) 261 conveying rollers (switchback conveying means, sheet conveying means) 270 regulating device (regulating section) 271c guide surface (conveying reference) S sheet SA LTR size sheet SB A4 size sheet

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Claims (6)

(57) [Claims] 1. A comprising a sheet <br/> over preparative conveying means having a conveying roller for conveying the sheet, and a regulating section for setting a conveyance reference position of the sheet in the downstream portion of the sheet conveying means, the regulating
Is a position that regulates the position of one side edge of the sheet to the transport reference position.
The guide surface fixed in place and the sheet
In a sheet conveying apparatus having a skew feeding roller that moves toward a sheet, the sheet conveying unit conveys a sheet toward the regulating unit with almost no change in the position in the width direction of the sheet.
Mode and by moving the transport roller in the width direction of the sheet.
A second mode in which the sheet is moved toward the regulation reference position side of the regulation section by the sheet conveyance means and is conveyed toward the regulation section, and according to the width size of the sheet, A sheet conveying apparatus, wherein the first mode or the second mode is selected. 2. The sheet carrying means is a switchback carrying means for carrying out a switchback carrying of the sheet after the normal carrying, and during the switchback carrying, the sheet is moved to a carrying reference position side of the regulating section. Item 1
The sheet conveying apparatus according to item 1. 3. A roller pair for nipping and conveying the sheet is used as the sheet conveying means, and one of the rollers of the roller pair moves in the axial direction, whereby the sheet being conveyed by the roller pair. 3. The sheet conveying apparatus according to claim 1, wherein the sheet conveying device moves to the conveying reference position side of the regulation unit. 4. The sheet conveying means, when conveying a sheet having a width size other than a maximum width size sheet, moves the sheet to a conveyance reference position side of the regulation section. The sheet conveying device described. 5. The sheet conveying apparatus according to claim 1, wherein the restriction portion is positionally fixed at a position that restricts a position in the width direction of a sheet having a maximum width size. 6. A sheet carrying device according to claim 1, and a sheet processing means for carrying out a predetermined process on a sheet carried by the sheet carrying device. Sheet processing device.