JP7171329B2 - Sheet conveying device and image forming device - Google Patents

Description

The present invention relates to a sheet conveying device for conveying sheets and an image forming apparatus having the same.

Conventionally, there has been proposed a medium printing apparatus that has a drive roller and a pinch roller that rotates following the drive roller, and that conveys a sheet to a medium conveyance path formed by a pair of guide plates (Patent Document 1). The pinch roller is rotatably supported by a pinch roller support, and the pinch roller support is rotatably supported about a fulcrum shaft. A guide portion protruding into the medium transport path is formed in the pinch roller support portion, and the sheet guided by the pair of guide plates is guided by the guide portion to the nip portion formed by the driving roller and the pinch roller. be done.

JP 2005-88216 A

However, the pinch roller support portion described in Patent Document 1 rotates around the fulcrum shaft in accordance with the thickness of the sheet, wear of the roller, etc., and the rotation of the pinch roller support portion causes the guide portion and the guide plate to rotate. The relative position with changes. In particular, when viewed in the axial direction of the pinch roller, the angle formed by the guide portion and the guide plate changes.

In general, the closer the angle between the guide portion and the guide plate is to 180 degrees, the less the sheet conveying resistance and the smoother the leading end of the sheet is guided to the nip portion. When the pinch roller supporting portion rotates and the angle formed by the guide portion and the guide plate becomes smaller, the impact when the leading edge of the sheet collides with the guide portion increases, and there is a risk of generating a large impact noise. be.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a sheet conveying device and an image forming apparatus in which a second guide surface is provided on a sliding member that slides integrally with a second rotating body, thereby solving the above-described problems.

According to the present invention, in a sheet conveying apparatus, a rotatable first rotating body and a second rotating body forming a nip portion for conveying a sheet together with the first rotating body and being driven to rotate with respect to the first rotating body. a slide member slidably movable integrally with the second rotor to contact and separate from the first rotor; a biasing member biasing the slide member toward the first rotor; A first guide surface arranged upstream of the nip portion in the sheet conveying direction to guide the sheet toward the nip portion; and a second guide surface provided on the slide member to guide the sheet toward the nip portion. and an upstream rotator pair arranged upstream of the first guide surface in the sheet conveying direction for conveying the sheet, and when viewed in the axial direction of the second rotator, the first guide surface and the The outer peripheral surface of the second rotating body intersects at a first intersection, and the second guide surface guides the sheet transferred from the first guide surface to the nip portion without guiding the sheet to the first intersection. When viewed in the axial direction, the first guide surface and the second guide surface intersect at a second intersection, the second intersection is positioned upstream of the first intersection in the sheet conveying direction, and the The first guide surface is curved and intersects the nip line of the pair of upstream rotors upstream of the second intersection point in the sheet conveying direction.

According to the present invention, it is possible to reduce the impact noise when the leading edge of the sheet collides with the outer peripheral surface of the driven roller.

1 is an overall schematic diagram showing a printer according to a first embodiment; FIG. FIG. 2 is a perspective view showing a skew correction device; FIG. 4 is a side view showing a shutter cam and a shutter member; The perspective view which shows a slide member. Sectional drawing which shows a slide member. FIG. 10A is a side view showing the skew correction device according to Comparative Example 1, in which (a) shows a state in which the guide arm is in a normal position, and (b) shows a state in which the guide arm is rotated upward; (a) is a side view showing the skew correction device according to Comparative Example 2, and (b) is a side view showing the skew correction device according to the present embodiment. 10A and 10B are cross-sectional views showing a skew correction device according to Comparative Example 2, where (a) shows a state in which the leading edge of the sheet collides with the driven roller to form a loop, and (b) shows a state in which the loop of the sheet is released; indicates FIG. 4 is a side view showing the arrangement of the second guide surface of the slide member according to the first embodiment; 9 is a graph showing impulsive sounds in Comparative Example 2 and the first embodiment; FIG. 11 is a perspective view showing a sheet conveying device according to a second embodiment; FIG. 5 is a side view showing the arrangement of the second guide surface of the slider member; The perspective view which shows the slider member which concerns on 3rd Embodiment.

An image forming apparatus according to the present disclosure will be described below with reference to the drawings. 2. Description of the Related Art Image forming apparatuses include printers, copiers, facsimiles, and multifunction machines, and form images on sheets used as recording media based on image information input from an external PC or image information read from a document. Sheets used as recording media include paper such as paper and envelopes, plastic film for overhead projectors, and cloth.

<First Embodiment>
〔overall structure〕
First, a first embodiment of the present invention will be described. A printer 100 as an image forming apparatus according to the first embodiment is an electrophotographic full-color laser beam printer. As shown in FIG. 1, the printer 100 includes a feeding unit 200 that feeds a sheet, a skew correction device 300 that conveys the sheet fed by the feeding unit 200, and an image forming device that forms an image on the sheet. and a part 400 . The printer 100 also has a fixing device 12 that fixes an image formed by the image forming section 400 onto a sheet, and a pair of discharge rollers 11 that discharges the sheet to the outside. As an option, a document reading device for reading an image of a document may be provided above the printer 100 .

When an image forming command is output to the printer 100 , the image forming process by the image forming unit 400 is started based on image information input from an external computer connected to the document reading device or the printer 100 . The image forming section 400 includes a scanner unit 2 and four process cartridges 7Y, 7M, 7C, and 7Bk for forming four-color images of yellow (Y), magenta (M), cyan (C), and black (Bk). , is equipped with The four process cartridges 7Y, 7M, 7C, and 7Bk have the same configuration except that the colors of the images formed are different, so only the image forming process of the process cartridge 7Y will be described, and the processes of the process cartridges 7M, 7C, and 7Bk will be described. Description is omitted.

The scanner unit 2 irradiates the photosensitive drum 1 of the process cartridge 7Y with laser light based on the input image information. At this time, the photosensitive drum 1 is charged in advance by a charging roller (not shown), and an electrostatic latent image is formed on the photosensitive drum 1 by being irradiated with the laser light L from the scanner unit 2 . Thereafter, the electrostatic latent image is developed by a developing roller (not shown) to form a yellow (Y) toner image on the photosensitive drum 1 .

Similarly, toner images of magenta (M), cyan (C) and black (Bk) are also formed on the photosensitive drums of the process cartridges 7M, 7C and 7Bk. The toner images of respective colors formed on the respective photosensitive drums are transferred onto the intermediate transfer belt 9 by the primary transfer rollers 5Y, 5M, 5C and 5Bk, and transferred to the secondary transfer roller 6 by the intermediate transfer belt 9 rotated by the belt drive roller 8. transported to. The image forming process for each color is performed at the timing of superimposing the upstream toner image that has been primarily transferred onto the intermediate transfer belt 9 .

In parallel with the image forming process described above, the sheet S is fed by the feeding section 200 . The feeding section 200 has a cassette 10 that can be pulled out from and mounted on the printer main body 100A, and a middle plate 22 that is vertically supported by the cassette 10 and on which sheets S are stacked. The sheets S stacked on the intermediate plate 22 are fed by the pickup roller 15 and separated one by one by the feed roller 16 and the separation roller 17 . A torque limiter (not shown) is connected to the separation roller 17, and the torque limiter applies a rotational load to the separation roller 17, thereby separating the sheets one by one.

The sheet S fed by the feeding unit 200 is conveyed toward the skew correction device 300 by the pair of conveying rollers 18 as the pair of upstream rotating bodies. The skew of the sheet S is corrected by the leading edge of the sheet abutting against the skew correcting device 300 as a sheet conveying device. Then, the sheet S is conveyed at the timing when it is aligned with the toner image on the intermediate transfer belt 9 by the skew correction device 300 .

A full-color toner image on the intermediate transfer belt 9 is transferred onto the sheet S by the secondary transfer roller 6 . The fixing device 12 applies predetermined heat and pressure to the sheet S onto which the toner image has been transferred, thereby melting and fixing the toner. After passing through the fixing device 12 , the sheet S is discharged onto a discharge tray 13 formed on the upper surface of the printer 100 by a discharge roller pair 11 .

[Skew correction device]
Next, the skew correction device 300 will be described in detail. As shown in FIG. 2, the skew correction device 300 includes a drive shaft 3a that rotatably supports a plurality of (five in this embodiment) drive rollers 3, and a shutter shaft 27 that extends parallel to the drive shaft 3a. ,have. A driving force is input to the driving shaft 3a from a motor (not shown), and the plurality of driving rollers 3 are driven by the driving force of the motor. The skew correcting device 300 has the same number of driven rollers 4 as the driving rollers 3. Each driven roller 4 forms a nip portion N for conveying the sheet together with the driving rollers 3. 3 is driven to rotate. A driving roller 3 as a first rotating body and a driven roller 4 as a second rotating body constitute a registration roller pair 23 .

A plurality of (four in this embodiment) shutter members 24 are fixed to the shutter shaft 27 in the same phase. are placed between 4. A shutter cam 28 is fixed to one axial end of the shutter shaft 27, and the shutter shaft 27, the shutter member 24 and the shutter cam 28 rotate together.

As shown in FIG. 3, the shutter member 24 has three abutment surfaces 24a, and the shutter cam 28 has three recesses 28a. The skew correcting device 300 has a pressing member 29 that can swing about a swing shaft 29a, and a cam follower 31 is rotatably supported at the tip of the pressing member 29. As shown in FIG. The pressing member 29 is urged by the shutter spring 30 in the direction in which the cam follower 31 approaches the shutter cam 28 .

The shutter cam 28 is held in a state in which the cam follower 31 is pressed against one of the recesses 28a, and at this time, one of the three abutment surfaces 24a protrudes into the conveying path through which the sheet passes. The abutment surface 24a protruding into the conveying path is located upstream of the nip portion N in the sheet conveying direction.

Therefore, the sheet S conveyed by the conveying roller pair 18 collides with the abutment surface 24a of the shutter member 24 protruding into the conveying path before entering the nip portion N of the registration roller pair 23 . The leading edge of the sheet S abuts against the abutment surfaces 24a of the shutter members 24, thereby correcting the skew of the sheet S. As shown in FIG. The rotation of the shutter member 24 is regulated by the biasing force of the shutter spring 30, and the sheet S forms a loop with the leading edge abutting against the abutment surface 24a. Further, when the sheet S is conveyed by the conveying roller pair 18, the pressing force of the sheet S exceeds the biasing force of the shutter spring 30, and the shutter member 24 rotates.

The sheet S enters the nip portion N of the registration roller pair 23 in a state where the skew is corrected, and the registration roller pair 23 conveys the sheet S at the timing when it is aligned with the toner image on the intermediate transfer belt 9. do. The shutter member 24 waits in contact with the surface of the sheet S being conveyed, and when the trailing edge of the sheet S passes through the shutter member 24, the cam follower 31 enters the next concave portion 28a and stops rotating. In this state, the shutter member 24 has the next abutment surface 24a protruding into the conveying path and prepares for the succeeding sheet. Thus, the shutter member 24 and the shutter cam 28 rotate by 120 degrees each time one sheet S passes.

[Peripheral Configuration of Driven Roller]
As shown in FIGS. 4 and 5, the driven roller 4 has a hollow shaft portion 4a through which the shutter shaft 27 passes. The shaft portion 4a protrudes outward from the outer peripheral surface 4b of the driven roller 4 that contacts the sheet S in the axial direction. A feed frame 25 as a frame member is fixed to the printer body 100A (see FIG. 1). The feeding frame 25 is provided with a curved first guide surface 25a for guiding the sheet S and a guide groove 25b for slidably supporting the shaft portion 4a of the driven roller 4. As shown in FIG. The driven roller 4 is moved by the guide groove 25b in the direction in which the straight line connecting the drive shaft 3a and the shutter shaft 27 extends (the direction of the arrow CD in FIG. 5), that is, in the direction in which the driven roller 4 comes into contact with and separates from the drive roller 3. It is possible to slide to

The skew correcting device 300 also has the same number of slide members 21 as the driven rollers 4, which are bearing members that rotatably support the shaft portions 4a of the driven rollers. It has a slide portion 21b that is movably supported. That is, a plurality of driving rollers 3, driven rollers 4, and slide members 21 are arranged side by side in the axial direction. A spring 26 as an urging member is stretched between the slide member 21 and the feeding frame 25 , and the driven roller 4 is moved through the slide member 21 by the urging force of the spring 26 to move the drive roller 4 . 3 is biased. Thus, the slide member 21 can slide in the direction of the arrow CD with respect to the drive roller 3 together with the driven roller 4 .

The driven roller 4 slides in the direction of the arrow CD depending on the thickness of the sheet S passing through the nip portion N and wear of the registration roller pair 23 . At this time, a sufficient clearance is ensured between the shaft portion 4a of the driven roller 4 having a hollow portion and the shutter shaft 27, and the biasing force of the spring 26 acts on the shutter shaft 27 from the driven roller 4. never. As a result, the biasing force of the spring 26 does not hinder the rotation of the shutter members 24 integrally fixed to the shutter shaft 27 . The slide member 21 also has a second guide surface 21a, which will be described later.

[Comparative Example 1]
Here, a skew correction device 300A according to Comparative Example 1 will be described with reference to FIG. As shown in FIGS. 6A and 6B, the skew correction device 300A includes a conveying guide 61 having a first guide surface 61a for guiding a sheet, and a rotating shaft 62b that rotates with respect to the conveying guide 61. and a movably supported guide arm 62 . The skew correcting device 300A also has a registration roller pair 65 consisting of a driving roller 63 and a driven roller 64. The driven roller 64 is rotatably supported by the guide arm 62. As shown in FIG. The guide arm 62 is urged by a torsion spring 66 screwed onto the rotary shaft 62b so that the driven roller 64 contacts the driving roller 63. As shown in FIG. The drive roller 63 and the driven roller 64 form a nip portion 65a that nips and conveys the sheet.

The guide arm 62 is formed with a second guide surface 62a that guides the sheet guided by the first guide surface 61a to the nip portion 65a. As shown in FIG. 6A, the angle θ1 is the angle formed by the first guide surface 61a and the second guide surface 62a. On the other hand, when the drive roller 63 is pressed by the driven roller 64 and the shaft of the drive roller 63 bends upward, as shown in FIG. It rotates upward compared to a). Therefore, the angle θ2 formed by the first guide surface 61a and the second guide surface 62a is smaller than the angle θ1 (θ2<θ1).

In general, the closer the angle between the first guide surface 61a and the second guide surface 62a is to 180 degrees, the less the sheet conveying resistance on the second guide surface 62a and the smoother the leading edge of the sheet is guided to the nip portion 65a. . As the angle formed by the first guide surface 61a and the second guide surface 62a becomes smaller, the impact when the leading end of the sheet collides with the second guide surface 62a becomes larger, causing an impact noise and causing the sheet to move. Posture is easily disturbed. In particular, this tendency is strong in cardboard with high rigidity. Further, due to the demand for miniaturization of the device and the purpose of cost reduction, there is a tendency for the components of the skew correction device 300A to be small. Become.

[Comparative Example 2]
Next, a skew correction device 300B according to Comparative Example 2 will be described with reference to FIGS. A skew correction device 300B according to Comparative Example 2 has a slide member 121 that slides integrally with the driven roller 4, as shown in FIG. 7A. It does not have the second guide surface 21a (see FIG. 7(b)). A skew correcting device 300B according to Comparative Example 2 differs from the skew correcting device 300 according to the present embodiment only in the shape of the slide member 121. Therefore, illustration of the same configuration as that of the present embodiment is omitted. , or will be described with the same reference numerals attached to the drawings.

As shown in FIG. 7A , the first guide surface 25 a and the outer peripheral surface 4 b of the driven roller 4 intersect at a first intersection 34 when viewed in the axial direction of the driven roller 4 . Further, the nip line L1 at the nip portion 18a of the conveying roller pair 18 intersects the first guide surface 25a upstream of a second intersection point 41, which will be described later, in the sheet conveying direction. Therefore, the leading edge of the sheet S transported by the transport roller pair 18 contacts the first guide surface 25a and is guided to the first intersection point 34 while sliding on the first guide surface 25a.

Then, as shown in FIG. 8A, the leading edge of the sheet S collides with the outer peripheral surface 4b of the driven roller 4 at the first intersection 34. As shown in FIG. At this time, a large impact sound is first generated. In a very short time after the leading edge of the sheet S collides with the outer peripheral surface 4b, the sheet S forms a small loop while the leading edge of the sheet S hits the outer peripheral surface 4b. Then, as shown in FIG. 8B, the moment the loop is released, the energy stored in the loop may cause the leading edge of the sheet S to vigorously collide with the abutment surface 24a of the shutter member 24. As shown in FIG. As a result, a loud impact noise may be generated and the posture of the seat S may be disturbed.

[Arrangement of second guide surface]
Therefore, in the present embodiment, the second guide surface 21a provided on the slide member 21 smoothly guides the leading edge of the sheet S to the nip portion N of the registration roller pair 23, thereby reducing the impact noise and reducing the sheet pressure. It suppresses the disturbance of the posture of S. As shown in FIG. 7B, at least a part of the second guide surface 21a in the present embodiment has a first intersection point 34 with respect to the rotation center 32 of the driven roller 4 when viewed in the axial direction of the driven roller 4. As shown in FIG. placed farther away than

More specifically, as shown in FIG. 9, when viewed in the axial direction of the driven roller 4, the first guide surface 25a and the second guide surface 21a intersect at the second intersection 41, and the second guide surface 21a and the driven roller 4 intersect each other. The outer peripheral surfaces 4 b of the rollers 4 intersect at a third intersection 42 . The second intersection point 41 is located upstream of the first intersection point 34 and the third intersection point 42 is located downstream of the first intersection point 34 in the sheet conveying direction. In this way, the second guide surface 21a is positioned between the second intersection point 41 and the third intersection point 42 more than the first intersection point 34, so that the conveyance between the conveyance roller pair 18 and the registration roller pair 23 at the nip portion N is greater than at the first intersection 34. It protrudes on the road CP side. Accordingly, the second guide surface 21 a can guide the sheet S transferred from the first guide surface 25 a to the nip portion N without guiding the sheet S to the first intersection 34 .

Further, the angle θ3 formed between the first guide surface 25a and the second guide surface 21a at the second intersection 41 is larger than the angle θ4 formed between the first guide surface 25a and the outer peripheral surface 4b of the driven roller 4 at the first intersection 34. is also big. Therefore, the leading edge of the sheet S is not stopped by the outer peripheral surface 4b of the driven roller 4 as described in Comparative Example 2, but is scooped up by the second guide surface 21a and smoothly guided to the nip portion N. As a result, it is possible to prevent the sheet S from generating a large impact sound in the vicinity of the driven roller 4, and to reduce the disturbance of the posture of the sheet S.

4, the second guide surface 21a of the slide member 21 includes a first guide portion 51 arranged on one side of the outer peripheral surface 4b of the driven roller 4 in the axial direction and a second guide portion 51 arranged on the other side of the outer peripheral surface 4b of the driven roller 4. and a second guide portion 52 arranged in the . The shaft portion 4a of the driven roller 4 and the first guide portion 51 and the second guide portion 52 partially overlap in the axial direction. As described above, since the first guide portion 51 and the second guide portion 52 are arranged on both sides of the outer peripheral surface 4b in the axial direction, the sheet S is stably nipped by the first guide portion 51 and the second guide portion 52. You can guide to Department N.

Further, in the present embodiment, the slide member 21 having the second guide surface 21a is configured so as to be slidably movable together with the driven roller 4, unlike the first comparative example. Thereby, there can exist the following effects.

First, it is possible to reduce the amount of variation in the protrusion amount d1 of the outer peripheral surface 4b of the driven roller 4 from the second guide surface 21a. That is, the slide member 21 is biased by the spring 26 to constantly press the shaft portion 4 a of the driven roller 4 at the slide portion 45 . Therefore, the dimensional tolerance of the dimension d2 from the sliding portion 45 to the second guide surface 21a can be minimized, and the amount of variation in the amount of protrusion d1 can be managed to a small value.

Second, even if the registration roller pair 23 moves, the angle θ3 can be kept constant. For example, when the driving shaft 3a is flexed by the biasing force of the spring 26, the registration roller pair 23 moves to the left side in FIG. In this case, the slide member 21 also slides leftward together with the registration roller pair 23, so that the projection amount d1 does not change. Therefore, at the intersection 42, the leading edge of the sheet S does not hit the outer peripheral surface 4b and increase the impact noise.

Further, as the slide member 21 moves, the relative positional relationship of the first guide surface 25a with respect to the slide member 21 becomes as indicated by the chain double-dashed line in FIG. Since the slide member 21 slides linearly along the guide groove 25b (see FIG. 5) of the feeding frame 25, even if the slide member 21 moves, the angle .theta.3 hardly changes. On the other hand, as in Comparative Example 1 described with reference to FIG. 6, when the guide arm 62 swings with the movement of the driven roller 64, the angle θ1 changes to the angle θ2 (<θ1). As a result, the collision between the leading edge of the sheet and the second guide surface 62a increases the impact, which tends to generate an impact sound and disturb the posture of the sheet. In contrast, in the present embodiment, the angle .theta.3 does not change regardless of the position of the driven roller 4, so impact noise and disturbance of the sheet posture can be reduced.

FIG. 10 is a graph showing the magnitude of the impact sound near the nip portion N in the present embodiment and Comparative Example 2. In FIG. In FIG. 10, the solid line indicates the magnitude of the impact noise in Comparative Example 2 without the second guide surface 21a, and the dashed line indicates the magnitude of the impact noise in the present embodiment with the second guide surface 21a. The horizontal axis of FIG. 10 indicates the elapsed time [ms] from the start of feeding the sheet S, and the vertical axis indicates the sound pressure level [dB]. At the elapsed time t<b>1 , the leading edge of the sheet S hits the outer peripheral surface 4 b of the driven roller 4 at the first intersection 34 . At the elapsed time t2, the leading edge of the sheet S strikes the abutment surface 24a of the shutter member 24. As shown in FIG.

In the case of Comparative Example 2 (indicated by the solid line), a large impact noise is generated from the moment the leading edge of the sheet S enters the driven roller 4 at the elapsed time t1, that is, at the first intersection point 34 . On the other hand, in the case of the present embodiment (indicated by the dashed line), the impact noise does not occur at the same timing as in Comparative Example 2, and the sheet S moves smoothly without generating a large impact noise at the second intersection 41 as well. It can be seen that the tip is transferred to the second guide surface 21a. Then, at the timing when the leading edge of the sheet S hits the abutment surface 24a of the shutter member 24, that is, at the elapsed time t2, a slight impact sound is generated. That is, it can be seen that the impact noise generated in the vicinity of the driven roller 4 is reduced.

In addition, when the second guide surface 21a is not provided as in Comparative Example 2, the loop formed in the sheet S is released, and the impact noise when the shutter member 24 collides with the abutting surface 24a is also louder. Become. In FIG. 10, before the impact sound generated at the first intersection point 34 is completely attenuated, the impact sound is also generated on the abutment surface 24a. The size of Comparative Example 2 is larger than that of the present embodiment.

<Second Embodiment>
Next, a second embodiment of the present invention will be described. In the second embodiment, a slide member similar to that of the first embodiment can slide integrally with the driven roller 36 of the conveying roller pair 18. It is set so that Therefore, the configuration similar to that of the first embodiment will be omitted from illustration or given the same reference numerals in the drawings.

A sheet conveying device 600 according to the second embodiment has a pair of conveying rollers 18 and a slide member 221, as shown in FIGS. The slide member 221 rotatably supports the shaft portion 36a of the driven roller 36 of the conveying roller pair 18, and is biased by a spring 226 as a biasing member so that the driven roller 36 presses the driving roller 35. ing. The slide member 221 has a slide portion 221b slidably supported in a guide groove (not shown) of the transport frame 37 . Thus, the slide member 221 can slide in the direction of the arrow with respect to the drive roller 35 integrally with the driven roller 36 .

[Arrangement of second guide surface]
In the present embodiment, the second guide surface 221a provided on the slide member 221 smoothly guides the leading edge of the sheet S to the nip portion 18a of the pair of conveying rollers 18, thereby reducing impact noise and correcting the posture of the sheet S. suppressing turmoil.

As shown in FIG. 12 , when viewed in the axial direction of the driven roller 36 , the first guide surface 37 a of the transport frame 37 as a frame member and the outer peripheral surface 36 b of the driven roller 36 intersect at a first intersection point 234 . When viewed in the axial direction of the driven roller 36, the first guide surface 37a and the second guide surface 221a intersect at a second intersection point 241, and the second guide surface 221a and the outer peripheral surface 36b of the driven roller 36 intersect at a third intersection point 242. intersect at The second intersection point 241 is located upstream of the first intersection point 234 and the third intersection point 242 is located downstream of the first intersection point 234 in the sheet conveying direction. In this manner, the second guide surface 221a projects further toward the transport path CP than the first intersection point 234 between the second intersection point 241 and the third intersection point 242 . Accordingly, the second guide surface 221 a can guide the sheet S transferred from the first guide surface 37 a to the nip portion 18 a without guiding it to the first intersection 234 .

Furthermore, the angle θ5 formed between the first guide surface 37a and the second guide surface 221a at the second intersection 241 is greater than the angle θ6 formed between the first guide surface 37a and the outer peripheral surface 36b of the driven roller 36 at the first intersection 234. is also big. Therefore, the leading edge of the sheet S is not stopped by the outer peripheral surface 36b of the driven roller 36, but is scooped up by the second guide surface 221a and smoothly guided to the nip portion 18a. As a result, it is possible to prevent the sheet S from generating a large impact sound in the vicinity of the driven roller 36 and to reduce the disturbance of the posture of the sheet S. Other effects of the second guide surface 221a of the slide member 221 are the same as those of the first embodiment, so description thereof will be omitted.

<Third Embodiment>
Next, a third embodiment of the present invention will be described. In the third embodiment, the slide member of the first embodiment is configured in a different shape. Therefore, the configuration similar to that of the first embodiment will be omitted from illustration or given the same reference numerals in the drawings.

As shown in FIG. 13, the slide member 321 that can slide integrally with the driven roller 4 has a second guide surface 321a that guides the sheet S toward the nip portion N. As shown in FIG. The second guide surface 321a includes the first guide portion 51 and the second guide portion 52 described above, and the third guide portion 53 arranged between the first guide portion 51 and the second guide portion 52 in the axial direction. have. The third guide portion 53 is arranged upstream of the outer peripheral surface 4b of the driven roller 4 in the sheet conveying direction. The third guide portion 53 can reliably guide the leading edge of the sheet S even if the leading edge of the sheet S is wavy, for example, and the leading edge of the sheet S does not abut against the outer peripheral surface 4 b of the driven roller 4 . prevent As a result, impact noise can be reduced. A plurality of third guide portions 53 may be provided between the first guide portion 51 and the second guide portion 52 .

In any of the above-described forms, the first guide surface and the second guide surface do not have to intersect when viewed in the axial direction of the driven roller. For example, in the first embodiment, when viewed in the axial direction, the first guide surface 25a and the second guide surface 21a do not have to intersect at the second intersection 41, and the first guide surface 25a and the second guide surface 21a may have a space. Similarly, the second guide surface and the outer peripheral surface of the driven roller do not have to intersect. In any case, the sheet should be transferred from the first guide surface 25 a to the second guide surface 21 a and the leading edge of the sheet should be guided to the nip portion N without being guided to the first intersection 34 .

Moreover, although the third embodiment is configured by modifying the first embodiment, the third embodiment and the second embodiment may be combined. Also, the present invention may be applied to any sheet conveying device including a pair of rollers in the printer 100 .

Further, in all of the above-described embodiments, the electrophotographic printer 100 is used in the description, but the present invention is not limited to this. For example, the present invention can also be applied to an inkjet image forming apparatus that forms an image on a sheet by ejecting ink liquid from nozzles.

3, 35: first rotating body (driving roller) / 4, 36: second rotating body (driven roller) / 4b, 36b: outer peripheral surface / 18: upstream rotating body pair (conveyance roller pair) / 18a, N: nip Part/21, 221: Slide member/21a, 221a: Second guide surface/25, 37: Frame member (feeding frame, conveying frame)/25a, 37a: First guide surface/26, 226: Biasing member ( spring)/34, 234: first intersection point/41, 241: second intersection point/42, 242: third intersection point/51: first guide portion/52: second guide portion/53: third guide portion/100: Image forming apparatus (printer)/300, 600: sheet conveying apparatus (skew correction apparatus)/400: image forming section/CP: conveying path/L1: nip line/.theta.3, .theta.4, .theta.5, .theta.6: angle

Claims (9)

a rotatable first rotating body;
a second rotating body that forms a nip portion for conveying a sheet together with the first rotating body and is driven to rotate with respect to the first rotating body;
a sliding member capable of sliding integrally with the second rotating body so as to come into contact with and separate from the first rotating body;
a biasing member that biases the slide member toward the first rotating body;
a first guide surface arranged upstream of the nip portion in the sheet conveying direction and guiding the sheet toward the nip portion;
a second guide surface provided on the slide member for guiding the sheet toward the nip portion;
an upstream rotator pair arranged upstream of the first guide surface in the sheet conveying direction and conveying the sheet ;
When viewed in the axial direction of the second rotating body, the first guide surface and the outer peripheral surface of the second rotating body intersect at a first intersection,
the second guide surface guides the sheet transferred from the first guide surface to the nip portion without guiding the sheet to the first intersection;
When viewed in the axial direction, the first guide surface and the second guide surface intersect at a second intersection;
the second intersection is positioned upstream of the first intersection in the sheet conveying direction;
the first guide surface is curved and intersects the nip line of the upstream rotor pair upstream of the second intersection point in the sheet conveying direction;
A sheet conveying device characterized by: When viewed in the axial direction, the second guide surface and the outer peripheral surface of the second rotating body intersect at a third intersection,
The second guide surface protrudes, between the second intersection point and the third intersection point, toward the conveying path through which the sheet passes from the first intersection point.
2. The sheet conveying apparatus according to claim 1 , wherein: The angle formed by the first guide surface and the second guide surface at the second intersection is greater than the angle formed by the first guide surface and the outer peripheral surface of the second rotating body at the first intersection,
3. The sheet conveying apparatus according to claim 1 , wherein: further comprising a frame member that slidably supports the second rotating body and the slide member, respectively;
4. The sheet conveying device according to any one of claims 1 to 3 , characterized in that: The second guide surface includes a first guide portion arranged on one side of the outer peripheral surface of the second rotating body in the axial direction, and a first guide portion arranged on the other side of the outer peripheral surface of the second rotating body in the axial direction. a second guide portion disposed;
The sheet conveying apparatus according to any one of claims 1 to 4 , characterized in that: The second guide surface is arranged between the first guide portion and the second guide portion in the axial direction, and is arranged upstream of the outer peripheral surface of the second rotating body in the sheet conveying direction. having a guide part,
6. The sheet conveying device according to claim 5 , characterized in that: A plurality of the first rotating body, the second rotating body, and the slide member are arranged side by side in the axial direction,
The sheet conveying device according to any one of claims 1 to 6 , characterized in that: Corrects the skew of the sheet by bumping the leading edge of the sheet.
The sheet conveying device according to any one of claims 1 to 7 , characterized in that: A sheet conveying device according to any one of claims 1 to 8 ;
an image forming unit that forms an image on the sheet;
An image forming apparatus characterized by:

Images