JP7497256B2 - Sheet conveying device and image forming apparatus - Google Patents

Description

The present invention relates to a sheet conveying device that conveys a sheet and an image forming apparatus equipped with the same.

Conventionally, sheet transport devices that transport sheets to an image forming section in a copier, printer, etc. have a rotating member that rotates around a rotation axis when pressed by a sheet, and are known to detect the passage of a sheet or the full load of sheets on an output tray by detecting the rotation of this rotating member.

The rotating member used in this type of sheet conveying device has a protrusion that protrudes from the outer circumferential surface of the rotating shaft, and the protrusion abuts against a restricting portion that is provided separately from the rotating member, thereby restricting the movement of the rotating shaft in the axial direction (thrust direction) (Patent Document 1).

JP 2017-81717 A

With regard to such a rotating member, there was a risk that a user might accidentally touch the rotating member, causing the protruding portion of the rotating member to be pressed against the restricting portion, placing a load on the protruding portion and causing the protruding portion to be damaged.

The present invention aims to prevent damage to the protrusion that restricts the axial movement of the rotating member when a load is applied to the protrusion.

One aspect of the present invention is a sheet conveying device that includes a conveying means for conveying a sheet, a rotating member having a rotating shaft and rotating when the sheet comes into contact with the rotating member, a detection means for detecting the rotation of the rotating member, and a regulating portion for regulating the axial movement of the rotating member, the rotating member having a contact portion for contacting the sheet and a plate-shaped protruding portion protruding from the outer circumferential surface of the rotating shaft and having a first surface that abuts against the regulating portion, the protruding portion having a rib on a second surface that is the surface opposite to the first surface.

The present invention provides a sheet conveying device that can prevent damage to a protrusion that restricts axial movement of a rotating member when a load is applied to the protrusion.

1 is a schematic diagram of an image forming apparatus according to an embodiment of the present invention. FIG. FIG. 4 is an enlarged view showing a protruding portion of the full load detection flag. FIG. FIG. FIG. FIG. 13 is a perspective view showing a state in which the fully loaded detection flag is bent.

Below, an image forming apparatus including a sheet conveying device according to this embodiment will be described with reference to the drawings. Note that the dimensions, materials, shapes, and relative positions of the components described in the following embodiments are not intended to limit the scope of application of this technology to those unless otherwise specified.

<General Configuration of Image Forming Apparatus>
A schematic configuration of an image forming apparatus 100 according to the present embodiment will be described with reference to Fig. 1. Fig. 1 is a cross-sectional view of an intermediate transfer tandem type image forming apparatus 100 in which four-color image forming units 140 using an electrophotographic method are arranged side by side on an intermediate transfer belt 145.

The image forming apparatus 100 has a sheet storage section 109 in which sheets S are stored as recording media. The sheets S stored in the sheet storage section 109 are fed by a pair of feed rollers 110 in accordance with the image formation timing of the image forming apparatus 100. The sheets S fed by the pair of feed rollers 110 pass through a conveying path and are conveyed to a pair of registration rollers 120. After the pair of registration rollers 120 corrects the skew and timing of the sheets S, the sheets S are sent to a secondary transfer section 130. The secondary transfer section 130 is composed of an inner secondary transfer roller 131 and an outer secondary transfer roller 132 that are substantially opposed to each other, and transfers a toner image onto the sheets S by applying a predetermined pressure force and an electrostatic load bias.

The image forming unit 140 as an image forming means includes a photoconductor 141, an exposure device 142, a developing device 143, and a primary transfer device 144. The exposure device 142 irradiates light based on the image information to be printed onto the photoconductor 141, the surface of which is uniformly charged by a charging device (not shown). This exposes the surface of the photoconductor 141, and an electrostatic latent image is formed on the surface of the photoconductor 141. The developing device 143 develops the electrostatic latent image thus formed on the photoconductor 141 with toner, and a toner image is formed on the photoconductor 141. Thereafter, a predetermined pressure force and an electrostatic load bias are applied by the primary transfer device 144, and the toner image is transferred onto the intermediate transfer belt 145. In this embodiment, the image forming apparatus 100 includes four sets of the image forming units 140 described above, for yellow Y, magenta M, cyan C, and black Bk.

Next, the intermediate transfer belt 145 will be described. The intermediate transfer belt 145 is driven to be transported in the direction of arrow A in FIG. 1. The image forming process by the image forming unit 140 for each color described above is performed at a timing when the image is superimposed on the upstream toner image that has been primarily transferred onto the intermediate transfer belt 145. As a result, a full-color toner image is finally formed on the intermediate transfer belt 145 and transported to the secondary transfer unit 130.

In the secondary transfer section 130, a full-color toner image is secondarily transferred from the intermediate transfer belt 145 onto the sheet S transported from the sheet storage section 109. The sheet S is then transported to the fixing device 150. The fixing device 150 has a heat source section 151 and a pressure section 152. The fixing device 150 melts and fixes the toner on the sheet S by a predetermined pressure force from the heat source section 151 and pressure section 152, which are approximately opposed to each other, and by heat from the heat source section 151. The heat source section 151 that heats the sheet S is disposed on the same side as the image forming surface of the sheet S, and the pressure section 152 that applies pressure to the sheet S is disposed on the opposite side.

In the case of single-sided printing, the sheet S on which the image has been fixed by the fixing unit 150 is discharged onto the discharge tray 170 as a stacking unit by the discharge rollers 161 as a conveying means. In the case of double-sided printing, the sheet S on which the image has been fixed on one side is branched off by the first switching flapper 153 and conveyed toward the reversing rollers 162.

Here, the sheet S conveyed to the reversing roller 162 is conveyed to the double-sided conveying path 180 by the reversing operation of the reversing roller 162 after the rear end of the sheet S passes the second switching flapper 154. The sheet S that temporarily jumps out of the machine during this reversing operation is supported by the reversing guide 171. The sheet S conveyed to the double-sided conveying path 180 is again subjected to skew correction and timing correction by the registration roller pair 120, and then sent to the secondary transfer section 130 where the image on the second side is transferred, and the transferred image is fixed by the fixing device 150. Then, the sheet S is discharged onto the discharge tray 170 by the discharge roller 161, and double-sided printing is completed. The discharge tray 170 on which the discharged sheet S is stacked has an upward slope from the upstream to the downstream in the discharge direction of the sheet S, so the discharged sheet S is aligned upstream in the discharge direction by the weight of the sheet S itself.

The image forming apparatus 100 has a control unit 190, which controls the sheet transport and image formation described above. In addition, a signal from the full-load detection sensor 165, which will be described later, is sent to the control unit 190.

<Configuration of full load detection flag>
Next, the configuration of the full-load detection flag will be described with reference to Figs. 2 to 7. Fig. 2 is a perspective view of the sheet discharge section B shown in Fig. 1. In this embodiment, the full-load state refers to a state in which the height of the sheets S stacked on the discharge tray 170 is equal to or greater than a predetermined height h. When the discharge tray 170 is fully loaded with the sheets S, there is a risk that the sheets S may fall off the discharge tray 170 or a jam may occur.

As shown in FIG. 2, the sheet discharge section B is provided with a full load detection flag 202, which is a rotating member, and a full load detection sensor (photointerrupter) 165, which is a detection means for detecting the rotation of the full load detection flag 202.

The full-load detection flag 202 has a contact portion 202a that contacts the sheet S, a light-shielding portion 202b that blocks the light of the full-load detection sensor 165, and a rotating shaft 202c. The contact portion 202a contacts the top sheet of the sheets S stacked on the discharge tray 170. Both ends of the rotating shaft 202c are rotatably supported by the first support portion 172 and the second support portion 173 provided on the main body side of the image forming apparatus 100. In addition, the rotating shaft 202c is positioned in the axial direction between the first support portion 172 and the second support portion 173 by the third support portion 174 as a regulating portion provided on the main body side of the image forming apparatus 100. In this embodiment, the axial direction is the direction in which the rotating shaft 202c extends. When the contact portion 202a of the full-load detection flag 202 is pressed by the sheet S, the rotating shaft 202c and the light-shielding portion 202b rotate together with the contact portion 202a. In other words, the more sheets S are stacked on the discharge tray 170 and the higher the height of the sheets S, the more the contact portion 202a is pushed upward by the topmost sheet S, and the more the full-load detection sensor 202 rotates.

When the sheets S stacked on the discharge tray 170 are not fully loaded (the height of the sheets S is less than h), the light-shielding portion 202b of the full-load detection flag 202 is in a position that blocks light from the light-emitting portion to the light-receiving portion of the full-load detection sensor 165. On the other hand, when the sheets S stacked on the discharge tray 170 are fully loaded (the height of the sheets S is h or more), the contact portion 202a is pressed by the top sheet S, and the full-load detection flag 202 is in a largely rotated state. Then, as a result of the rotation of the light-shielding portion 202b of the full-load detection flag 202, the light-shielding portion 202b moves to a position where it does not block the light of the full-load detection sensor 165, and the full-load detection sensor 165 can detect that the full-load detection flag 202 has rotated largely. Here, the control unit 190 can detect that the height of the sheets S is h or more based on the signal sent from the full-load detection sensor 165.

3 is an enlarged view of the vicinity of the first support portion 172, and FIG. 4 is a top view of the vicinity of the first support portion 172. FIG. 5 is a perspective view showing only the full load detection flag 202. The full load detection flag 202 has a plate-shaped first protrusion 202d and a second protrusion 202e protruding outward from the outer circumferential surface of the rotating shaft 202c. The first protrusion 202d is a flange-shaped protrusion with a large protrusion in one portion, and has a first abutment surface 202d1 (first surface) perpendicular to the axial direction. Furthermore, the first protrusion 202d is provided with a rib 202d2 protruding from a surface 202d3 (second surface) opposite to the first abutment surface 202d1. The rib 202d2 has a thin planar shape parallel to the axial direction of the rotating shaft 202c. In this embodiment, a rib is a protrusion provided to reinforce a member.

The rib 202d2 is provided in a region including the base of the first protrusion 202d. Here, the base of the first protrusion 202d is the boundary between the first protrusion 202d and the rotating shaft 202c. In other words, the rib 202d2 protruding from the first protrusion 202d is connected to the outer circumferential surface of the rotating shaft 202c.

The second protrusion 202e is a protrusion that protrudes from a part of the outer circumference of the rotating shaft 202c and has a second abutment surface 202e1 (first surface). A rib 202e2 is provided on a surface 202e3 (second surface) opposite to the second abutment surface 202e1 of the second protrusion 202e.

The third support portion 174 provided on the main body side of the image forming apparatus 100 has a notch portion 174a as a recess. The rotating shaft 202c fits into the notch portion 174a of the third support portion 174. As shown in FIG. 3 and FIG. 4, when the rotating shaft 202c is fitted into the notch portion 174a, the first protrusion portion 202d and the second protrusion portion 202e are located in positions sandwiching the third support portion 174 from both sides in the axial direction. As a result, the first abutment surface 202d1 of the first protrusion portion 202d and the second abutment surface 202e1 of the second protrusion portion 202e abut against the third support portion 174, thereby restricting the axial movement of the full load detection flag 202.

As shown in FIG. 3, the first support portion 172 has a round hole (hole portion) 172a, and the end of the rotating shaft 202c on the light-shielding portion 202b side is inserted into the round hole 172a of the first support portion 172. FIG. 6 is an enlarged view of the vicinity of the second support portion 173. As shown in FIG. 6, the second support portion 173 has a round hole (hole portion) 173a, and the end of the rotating shaft 202c on the contact portion 202a side is inserted into the round hole 173a of the second support portion 173. In other words, both ends of the rotating shaft 202c are inserted into two round holes 172a, 173a provided on the main body side of the image forming apparatus 100, and are supported so as to be freely rotatable.

<How to install the full load detection flag>
Next, a method of attaching the full-load detection flag 202 will be described. As described above, in this embodiment, both ends of the rotating shaft 202c are supported by being inserted into two round holes 172a, 173a provided on the main body of the image forming apparatus 100. Therefore, when attaching the full-load detection flag 202 to the first support portion 172 and the second support portion 173, one end of the rotating shaft 202c is inserted into the round hole 172a, and then the other end of the rotating shaft 202c is inserted into the round hole 173a while bending the rotating shaft 202c.

In FIG. 4, arrow C indicates the width of the notch 174a, and in FIG. 5, arrow D indicates the width of the second protrusion 202e. In this embodiment, the width C of the notch 174a is greater than the width D of the second protrusion 202e. Therefore, it is possible to attach the full-load detection flag 202 to the first support portion 172 and the second support portion 173 by aligning the phase of the second protrusion 202e with the phase of the notch 174a so that the second protrusion 202e passes through the notch 174a. This prevents the second protrusion 202e from contacting the third support portion when attaching the full-load detection flag 202 to the main body of the image forming device 100, making it easier to attach the full-load detection flag 202.

<About the deflection of the full load detection flag>
7 is a diagram showing the displacement of the rotation shaft 202c when the full-load detection flag 202 is bent. As shown in FIG. 1, the full-load detection flag 202 is provided on the upper part of the discharge tray 170. Therefore, when a user takes out a sheet S stacked on the discharge tray 170, the user may accidentally touch the contact portion 202a, or when the user returns the taken-out sheet S to the discharge tray 170, the sheet S may contact the contact portion 202a from the side. In such a case, a load is applied to the contact portion 202a in the direction of the arrow P, and the rotation shaft 202c is deformed into a shape shown by a dashed line in FIG. 7. At this time, the first abutment surface 202d1 of the first protrusion 202d is pressed against the third support portion 174, so that a load is applied to the first protrusion 202d in the opposite direction to the arrow P. However, in this embodiment, a rib 202d2 is provided on the surface 202d3 opposite the first abutment surface 202d1 of the first protrusion 202d, so that damage to the first protrusion 202d can be prevented even when a load is applied to the first protrusion 202d.

The rib 202d2 shown in this embodiment has a thin, planar shape parallel to the axial direction of the rotation shaft 202c, but the shape of the rib 202d2 is not limited to a thin, planar shape parallel to the axial direction of the rotation shaft 202c. For example, the rib 202d2 may be a protrusion having an arc-shaped cross section. In addition, the rib 202d2 may be a rib that does not extend parallel to the axial direction but is tilted relative to the axial direction.

In addition, although the rib 202d2 shown in this embodiment is provided in a region including the root of the first protrusion 202d, the rib 202d2 may be provided in a region that does not include the base of the first protrusion 202d. However, by providing the rib 202d2 in a region including the base of the first protrusion 202d as shown in this embodiment, it is possible to prevent the first protrusion 202d from breaking at the base. For this reason, it is desirable that the rib 202d2 be provided in a region including the base of the first protrusion 202d.

The first protrusion 202d protrudes significantly in the direction opposite to the deflection direction shown in FIG. 7, and the first contact surface 202d1 is larger than the notch 174a of the third support portion 174. Therefore, even if the rotation shaft 202c is deformed to the shape shown by the dashed line in FIG. 7, it is possible to prevent the rotation shaft 202c from coming off the third support portion 174. This configuration allows the rotation shaft 202c to deflect significantly, and therefore it is possible to prevent the full load detection flag 202 from being damaged when a load is applied to the full load detection flag 202.

In this embodiment, the full load detection flag 202 has two protrusions, a first protrusion 202d and a second protrusion 202e, and the first protrusion 202d and the second protrusion 202e are positioned to sandwich the third support portion 174, thereby restricting the axial movement of the full load detection flag 202. However, the rotating member may have one protrusion, and the protrusion may be configured to restrict the movement of the rotating member in only one direction.

In this embodiment, the protruding portion of the full stack detection flag 202 is exemplified, but the present invention can also be applied to a rotating member for detecting the passage of a sheet midway along the sheet transport path. Also, in this embodiment, an electrophotographic image forming unit is exemplified as an example of an image forming unit that forms an image on a sheet, but the image forming unit may be of an inkjet type.

100 Image forming apparatus 165 Full-load detection sensor 202 Full-load detection flag 202a Contact portion 202b Light shielding portion 202c Rotation shaft 202d First protrusion 202d1 First contact surface 202d2 Rib 202e Second protrusion 202e1 Second contact surface 202e2 Rib

Claims (10)

A conveying means for conveying a sheet;
A rotating member having a rotating shaft and rotated by contact with the sheet;
A detection means for detecting the rotation of the rotating member;
a restricting portion that restricts the rotation member from moving in an axial direction;
Equipped with
The rotating member is
A contact portion that contacts the sheet;
a plate-shaped protruding portion protruding from an outer circumferential surface of the rotating shaft, the plate-shaped protruding portion having a first surface that comes into contact with the restricting portion;
having
The sheet conveying device according to claim 1, wherein the protrusion has a rib on a second surface opposite to the first surface. The sheet conveying device according to claim 1, characterized in that the rib has a planar shape parallel to the axial direction. The sheet conveying device according to claim 1 or 2, characterized in that the rib is provided in an area that includes the base of the protrusion. The restricting portion has a recess,
4. The sheet conveying device according to claim 1, wherein the rotation shaft is fitted into the recess. The sheet conveying device according to claim 4, characterized in that the first surface is larger than the recess. The rotary shaft has a hole into which an end portion of the rotary shaft is inserted, and a support portion that rotatably supports the rotary shaft.
6. The sheet transport device according to claim 1, wherein the sheet transport device is a sheet conveying device. the rotating member has another protruding portion protruding from the rotating shaft,
7. The sheet conveying device according to claim 1, wherein the protruding portion and the another protruding portion are provided at positions sandwiching the regulating portion from both sides in the axial direction. a stacking section on which the sheets conveyed by the conveying means are stacked,
8. The sheet transport device according to claim 1, wherein the rotating member is provided such that the contact portion comes into contact with the sheets stacked on the stacking portion. The sheet conveying device according to claim 8, characterized in that the detection means is a full load detection sensor for detecting the full load of sheets in the stacking section by detecting the rotation of the rotating member. A sheet conveying device according to any one of claims 1 to 9,
an image forming means for forming an image on a sheet;
An image forming apparatus comprising:

Images