JP4530956B2 - Sheet conveying apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a conveyance device that conveys a thin object such as a sheet member using a conveyance member such as a roller, and an image forming apparatus such as a copying machine, a laser printer, a facsimile, and a scanner using the conveyance device.

  In an image forming apparatus such as a copying machine, a conveyance device that conveys a thin object such as a sheet or other recording medium or a sheet member using a conveyance member such as a roller is often used. Many technical proposals have been made.

  For example, Patent Document 1 discloses that in an automatic document feeder, when a document is discharged from an exposure unit, the conveyance force when the document trailing edge passes through the roller is reduced stepwise, and the abrupt feeding when the document trailing edge is removed. In order to minimize the unevenness of the conveyance speed by distributing the force change in the axial direction and to prevent the copy image distortion caused by the variation of the document speed, the conveyance roller and the pressure roller that convey the document to the exposure unit A technique is disclosed that suppresses a sudden change in feed force and prevents copy image distortion by differentiating the distance to each exposure position for the pressure roller group closest to the exposure position. In this technique, the pressure members that generate the conveying force are at different positions. Further, a difference is caused in the conveying force by each pressing member.

Further, for example, in Patent Document 2, in order to provide a stable and inexpensive conveying device that does not cause a difference in conveying force and surface pressure between rollers and that does not apply stress to the paper, the diameter of the driven roller at the center is set. When Dt is set, Dr is the diameter of the driven roller 2b at both ends, and δ is the amount of deflection generated at the center of the driven roller holding shaft when the driven roller comes into contact with the drive roller, the relationship between Dt and Dr is , Dt = Dr + 2 × δ
Thus, the nip width of the driven roller that contacts the drive roller is made equal, the conveying force of the driven roller at the center and the driven roller at both ends is equalized, and the contact pressure per unit contact area is reduced. A technique for making it constant is disclosed. This technology expects the driven roller to bend to eliminate the difference in conveying force between the rollers, but this may cause an increase in the load on the drive system and damage over time in a physically loaded state. is there.
JP 2001-066682 A JP 2002-173249 A

  1 and 2, there are several rollers 31... On the shaft 30, and a drive roller 32 whose both ends are rotatable and whose shaft center is fixed, and pressure is generated at the opposing positions of the rollers 31. The driven rollers 33 are in contact with each other, and these driven rollers 33 are configured to generate the pressure by an elastic member such as a spring 34.

  FIG. 1 shows that the rollers 31 of the driving roller 32 when used in the image forming apparatus are not arranged in a uniform manner with respect to the center line between the front plate (frame) 35 and the rear plate (frame) 36, for example. The case of arrangement biased to 36 is shown. The front side plate 35 and the rear side plate 36 are indicated by triangular figures in the figure as supporting points. At this time, the roller 31 of the driving roller 32 located at a position opposite to the biasing force of the spring 34 against the driven roller 33 closest to the rear side plate 36 is pushed, and the driving roller 32 bends as illustrated. Along with this, the contact position between the other roller 31 of the driving roller 32 and the driven roller 33 moves in the direction in which the spring 34 extends, and the urging force of the spring 34 against them decreases the load at the time of attachment, and the sheet member conveying force decreases. To do. Therefore, a difference in conveying force with the roller closest to the rear plate 36 is increased.

  FIG. 2 shows a case where the rollers 31 of the drive roller 32 are evenly arranged with respect to the center line between the front side plate 35 and the rear side plate 36. At this time, the roller 31 of the driving roller 32 located at the opposite position is pushed by the urging force of the spring 34 of the driven roller 33 close to the front side plate 35 and the rear side plate 36, and the driving roller 32 is also bent. Along with this, the contact position between the other roller 31 in the central portion of the drive roller 32 and the driven roller 33 moves in the direction in which the spring 34 extends, and the urging force of the spring 34 against them decreases the load when attached, and the sheet member is conveyed. The power drops. Therefore, the difference in conveying force with the rollers 31 at positions close to the side plates 35 and 36 increases.

Such a sheet member conveying apparatus has the following problems.
(1) Each roller of the driving roller is pushed by the pressure from the driven roller, and the driving roller is bent. As a result, the length of the spring that applies pressure to each roller varies depending on the roller, and when the spring is the same product (one type), the pressure at each roller is different and the conveying force of the sheet member such as paper is uniform. This causes a transport failure such as skew.
(2) It is possible to change the type of spring for each roller, assuming separate bending of the drive roller, and make it a separate part. However, the number of parts increases and the labor of parts management in the production area increases. Incorrect manufacturing of the spring in the manufacturing process is likely to occur.
(3) Although it is possible to make the roller shaft thicker in order to prevent the driving roller from being bent, there are concerns such as an increase in component weight, an increase in power consumption due to an increase in load torque, and a decrease in durability over time.

SUMMARY OF THE INVENTION An object of the present invention is to provide a sheet conveying apparatus that is a thin object that can solve such conventional problems, and an image forming apparatus using the sheet conveying apparatus.

A sheet conveying apparatus according to claim 1 of the present invention includes a driving roller that is rotatably supported at both ends of a rotating shaft;
A plurality of driven rollers that rotate with the rotation of the drive roller , all have the same shape and the same size, and are evenly arranged corresponding to the drive roller ;
A plurality of driven roller support members for rotatably supporting the driven roller ;
In the sheet conveying apparatus and a plurality of biasing members the driven roller respectively biasing the front Ki従 dynamic roller supporting member so as to press the drive roller,
The bracket is a common plate-like member that is assembled to the guide plate frame that supports the biasing member and conveys the sheet member on the surface thereof,
The biasing member has one end engaged with the driven roller support member and the other end engaged with the bracket.
In order to reduce the amount of bending of the rotating shaft caused by the driven roller being pressed against the driving roller, a plurality of opposed portions that respectively support the biasing means of the bracket and face the biasing means are provided in the axial direction. A concave portion in which the bracket is dented in a direction farther from the driving roller as the opposing portion is closer to the opposing portion located at the center of the driving roller.
Sheet conveying force by the slave moving roller and the drive roller is characterized by substantially equal in the longitudinal direction of the rotary shaft.

Those according to the second aspect, the sheet transporting device according to claim 1, wherein the plurality of slave moving roller support member is characterized Rukoto such a wear resistant material.

Those according to the third aspect, the sheet transporting device according to claim 1 or 2, wherein the biasing member and wherein the compression spring der Rukoto.

The image forming apparatus according to the claim 4, characterized Rukoto including a sheet conveying device according to any one of claims 1 to 3.

The present invention is capable of preventing the above-described conventional problems and suppressing the bending of the driving roller due to the spring force of the driven roller close to the support site without increasing the type of spring and without increasing the shaft diameter of the driving roller. , It is possible to suppress a decrease or decrease in the conveyance force between the driving member and the driven member that are separated from the support site, and the difference in the conveyance force at each contact site between the driving member and the driven member is eliminated or reduced, and there is no skew or the like. Stable sheet conveyance is possible.

  The best mode for carrying out the present invention will be described below with reference to the embodiments shown in the drawings.

FIG. 9 shows an image forming apparatus that can be provided with a sheet conveying apparatus according to the present invention, and is an explanatory diagram showing a conveying path of a transfer material that is a sheet-like member such as a sheet that is an example of a thin object. is there. In this image forming apparatus, two-stage sheet cassettes 1a and 1b are arranged in the lower part of the apparatus body, and when a sheet feed command is issued, a sheet as a recording medium is separated and fed from one sheet cassette 1 Are fed one by one. The fed paper passes through the grip roller pair 3 and reaches the registration roller pair 5 through the intermediate roller pair 4 at the junction with the refeed conveyance path. The separating / feeding means 2, the grip roller pair 3, the intermediate roller pair 4 and the registration roller pair 5 are each configured to be independently driven by a clutch, a stepping motor or the like.

  Reference numeral 6 in the drawing denotes a photosensitive drum as an image carrier. A toner image is formed on the photosensitive drum 6 by a known electrophotographic process. The toner image is transferred to the transfer position of the photosensitive drum 6 in synchronization with the image. After the transfer, the sheet is conveyed to the fixing device 7 where the toner image is fixed on the sheet.

  When the paper on which image formation has been completed is not reversed, it is conveyed straight to the paper discharge roller 9 and discharged outside the apparatus. When reverse paper discharge or double-sided copy is selected, the paper is conveyed to the reverse device 10 by switching the branching claw 8.

  The reversing device 10 includes a reversing forward path 11 that communicates with the intermediate tray 12 and a reversing backward path 13 that communicates from the intermediate tray 12 to the paper discharge roller 9. The sheet fed into the reverse path 11 is sandwiched between the reverse roller pairs 15 and 16 via the transport roller pair 14 and is sent to the intermediate tray 12 by the transport action. The intermediate tray 12 is provided with switchback roller pairs 20 and 21. The upper switchback roller 20 can be brought into and out of contact with the lower switchback roller 21 by using a solenoid (not shown) as a drive source.

  The reverse path 11 is provided with an inlet sensor 22 on the upstream side of the pair of reverse rollers 15 and 16, and when the inlet sensor 22 detects the leading edge of the paper, the switchback roller rotates to receive the paper with the detection as a trigger. Driving is stopped when the trailing edge of the paper reaches a predetermined paper stop position. Thereafter, the pair of switchback rollers 20 and 21 are driven in the reverse direction, and the sheet is conveyed in the direction opposite to the entering direction with the trailing edge as the leading edge.

  The sheet sandwiched between the reversing roller pairs 16 and 17 is conveyed by its conveying action, and the upper switchback roller 20 is driven by a solenoid (not shown) to move to the chain line position, whereby the next sheet is fed to the intermediate tray 12. Can enter. In addition, a switching claw 23 provided subsequent to the intermediate tray 12 switches the transport direction between reverse discharge and double-sided copying. The sheet to be switched back is conveyed on the reverse return path 13 by the upper switchback roller 20, the lower switchback roller 21, and the reversing rollers 16 and 17, and is conveyed to the paper discharge roller 9 through the conveying roller pairs 24 and 14, and then to the machine. The sheet is discharged to the outside or sent along the reversing roller 17 and sent to the registration roller pair 5 through the refeed conveyance path 25 and the intermediate roller pair 4 provided below the intermediate tray 12, When image formation is completed on the back side, the paper is discharged out of the machine.

3 and 4 are perspective views showing the configuration of the first embodiment of the present invention. In the figure, reference numeral 51 denotes a driving roller. Although illustration of the vicinity of the both ends is omitted, it is supported by a bearing or the like on a component such as a side plate of the image forming apparatus, and can freely rotate at a fixed position. In the figure, reference numeral 52 denotes a shaft of the driving roller 51, and 53 denotes a roller of the driving roller 51. These are assembled to the shaft 52 and rotate at the same rotational speed as the shaft 52 rotates. In the figure, 54 indicates a driven roller, and 55 indicates an arm that supports the driven roller. As shown in FIG. 4, the driven roller 54 is assembled to the arm 55 so as to be freely rotatable. In the figure, reference numeral 56 denotes a guide plate frame. The guide plate frame 56 is a guide for conveying the sheet member on the surface thereof, and is a support member for assembling the arm 55. In the figure, reference numeral 57 denotes a bracket, which is assembled to the guide plate frame 56. In the figure, reference numeral 59 denotes a nip portion where the roller 53 of the driving roller and the driven roller 54 are in contact with each other. Also, each driven roller 53 of the drive roller 51 has the same diameter, and all the driven rollers 54 have the same diameter. The arm 55, created in耐磨耗材 fee. For example, polyacetal which is an engineering plastic is suitable as a resin material.

  FIG. 5 is a perspective view of the unit shown in FIG. 3 as viewed from the lower side of FIG. In the figure, reference numeral 58 denotes a compression spring as an example of an elastic member. One end of the compression spring 58 is assembled to the arm 55, and the other end is assembled to the bracket 57.

FIG. 6 shows a perspective view (A) of the bracket 57 and a side view in the direction of arrow A. FIG. The parts a to d where the compression springs 58 are assembled are not on the same plane and have different positional relationships. That position b and c is in the same position without concave on the surface of the bracket 57 as shown, deeply position d is dented compared to these, a is deeper be recessed further.

FIG. 7 shows a simplified diagram of FIG. 3 corresponding to FIG. The case where the rollers 53 of the driving roller 51 are not arranged in an equal arrangement between the front side plate 35 and the rear side plate 36, but is, for example, an arrangement that is biased toward the rear side plate 36 is shown. Each roller of the driving roller 51 is made 53a, 53b, 53c, 53d from the rear side plate, and the driven roller is similarly made 54a, 54b, 54c, 54d. These positional relationships are as illustrated. The portion of the bracket 57 that receives the other end of the compression spring 58 of the driven roller 54a closest to the rear side plate 36 is recessed and lower than the portion that receives the other ends of the compression springs 58 for the other driven rollers 54b to 54d. is there. The portion of the bracket 57 that receives the compression spring 58 of the driven roller 54d is higher than the portion that receives the compression spring 58 for the driven roller 54a, and is recessed and lower than the compression spring 58 for the driven rollers 54b and 54c.

  With this configuration, the attachment length of the compression springs 58 for the driven rollers 54a and 54d close to the side plates 35 and 36 is longer than that in the state of FIG. 1, and the load when the compression springs 58 are attached becomes weak. The amount of bending of the shaft 52 can be reduced. At this time, the attachment lengths of the respective compression springs 58 of the driven rollers 54a to 54d are substantially the same, and substantially the same spring force is applied to each of the driven rollers 54a to 54d. The difference narrows and becomes almost the same.

  FIG. 8 shows a second embodiment of the present invention. In this embodiment, the rollers 53 of the driving roller 51 are equally arranged with respect to the center line between the front side plate 35 and the rear side plate 36. The rollers of the driving roller 51 are indicated by 53e to 53h from the rear side plate 36, and the driven rollers are similarly indicated by 54e to 54h. These positional relationships are as indicated in the figure. The portion of the bracket 57 that receives the other end of the compression spring 58 of the driven rollers 54e and 54h close to each side plate (frame) is at a lower position than the portion that receives the compression spring 58 for the other driven rollers 54f and 54g.

  With this configuration, the attachment length of the compression springs 58 for the driven rollers 54e and 54h close to the side plates 35 and 36 is longer than that in the example of FIG. 2, and the load when the compression springs 58 are attached becomes weak, and the drive roller 51 is bent. The amount can be reduced. At this time, the attachment lengths of the respective compression springs 58 of the driven rollers 54e to 54h are substantially the same, almost the same spring force is applied to each of the driven rollers 54e to 54h, and the conveying force at each of the nip portions 59 is also substantially the same. It will be the same.

  That is, in the present invention, without increasing the type of spring and without increasing the shaft diameter of the drive roller, the deflection of the drive roller due to the spring force of the driven roller close to each side plate (frame) can be suppressed. It is possible to suppress a decrease or decrease in the conveyance force at the nip part located in the middle of the distance, eliminating or reducing the difference in conveyance force at each nip between each roller of the driving roller and the driven roller, and stable without skew etc. The sheet member can be conveyed.

Also, if one end of each spring that generates pressure is supported by a separate member, the distance between these members and the distance from the driven roller will vary due to the variation in dimensions and assembly. As the dimensions become unstable, the pressure of the driven roller generated by the springs becomes unstable, that is, the conveying force becomes unstable, causing a skew or the like. In the present invention, as shown in FIG. Since it is assembled to the bracket 7 which is a common component, problems can be eliminated.

  Also, if the dimensions of the roller of the driving roller and the driven roller are different, that is, the length of the spring mounting portion will naturally change, it will be difficult to maintain the aim of eliminating the difference in conveying force between the rollers. Because the roller roller and the driven roller have the same diameter (same size), the difference in the nip position (layout) between each roller is minimized, and the dimension of the distance to install the spring is the minimum number of parts stacked. The mounting distance of the spring can be further improved, and the load at the time of mounting the spring force of each roller can be made the same or close to the same, the difference in conveying force at each nip can be minimized, and the skew etc. It is possible to stably convey the sheet member.

  Also, when a strong conveying force is required, the spring force is increased and the driven roller is pressed strongly against the drive roller. If the driven roller is composed of a roller and a member that supports the roller, Although a large force is applied and wear progresses and sliding resistance increases, in the present invention, the rollers of the driving roller have the same diameter, and the plurality of driven rollers have the same diameter and the same dimensions. Therefore, the sheet member can be stably conveyed without skew.

In addition, when the spring force is increased due to the strong conveying force, the driven roller is strongly pressed against the drive roller, and the reaction force increases the sliding resistance between the driven roller and the fitting part of the arm, but the arm is highly durable. and suppressing wear and degradation by the use of high wear resistant material, stable operation.

Simplified view of a conventional sheet transport device Simplified view of a conventional sheet transport device The perspective view which shows the structure of 1st Example of this invention. The perspective view which shows the structure of 1st Example of this invention. The perspective view which looked at the unit shown in FIG. 3 from the lower side of FIG. The perspective view (A) of the bracket of the unit shown in FIG. 3, and the side view of the arrow A direction 3 is a simplified diagram corresponding to FIG. Simplified diagram of the second embodiment of the present invention 1 is a diagram illustrating an image forming apparatus that can include a sheet conveying device according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Paper feed cassette 2 Separation paper feed means 3 Grip roller 4 Intermediate roller 5 Registration roller 6 Photosensitive drum 7 Fixing device 8 Branch claw 9 Paper discharge roller 10 Reverse device 11 Reverse forward path 12 Intermediate tray 13 Reverse reverse path 14 Conveying rollers 15 and 17 Reverse roller (drive roller)
16, 16a, 16b Reverse roller (driven roller)
16c Shaft of reverse roller (driven roller) 18 Spring 19 Solenoid 20, 21 Switchback roller 22 Inlet sensor 23 Switching claw 24 Transport roller 25 Refeed transport path 35 Front plate 36 Rear plate 51 Drive roller 52 Drive roller shaft 53, 53a to 53h Roller 54 of driving roller, 54a to 54h Followed roller 55 Arm 56 Guide plate frame 57 Bracket 59 Nip part 58 Compression spring

Claims (4)

A driving roller rotatably supported at both ends of the rotating shaft;
A plurality of driven rollers that rotate with the rotation of the drive roller , all have the same shape and the same size, and are evenly arranged corresponding to the drive roller ;
A plurality of driven roller support members for rotatably supporting the driven roller ;
In the sheet conveying apparatus and a plurality of biasing members the driven roller respectively biasing the front Ki従 dynamic roller supporting member so as to press the drive roller,
The bracket is a common plate-like member that is assembled to the guide plate frame that supports the biasing member and conveys the sheet member on the surface thereof,
The biasing member has one end engaged with the driven roller support member and the other end engaged with the bracket.
In order to reduce the amount of bending of the rotating shaft caused by the driven roller being pressed against the driving roller, a plurality of opposed portions that respectively support the biasing means of the bracket and face the biasing means are provided in the axial direction. A concave portion in which the bracket is recessed in a direction farther from the driving roller as the opposing portion is closer to the opposing portion located at the center portion of the driving roller.
Sheet conveying apparatus a sheet conveying force by the slave moving roller and the drive roller, characterized in that substantially equal in the longitudinal direction of the rotary shaft.
In the sheet conveying apparatus according to claim 1,
Wherein the plurality of slave moving the roller support member sheet conveying apparatus according to claim Rukoto such a wear resistant material. In the sheet conveying apparatus according to claim 1 or 2,
Sheet conveying apparatus wherein the biasing member and wherein the compression spring der Rukoto. An image forming apparatus comprising Rukoto including a sheet conveying device according to any one of claims 1 to 3.