JPH07165347A - Sheet carrier device of image forming device - Google Patents

Abstract

PURPOSE:To prevent a sheet from making a skew by displaying carrier work by rotation of a bar type roller member even against a small size sheet in a device constituting a carrier roller device of a drive roller and a bar type pinch roller. CONSTITUTION:A carrier roller device 10 arranged on a sheet carrier passage is constituted of a drive roller 11 provided with roller members 15-19 in a skewered form on a drive shaft 12 and a bar type roller member 20 provided with a round bar type member free to rotate through a bearing which are arranged to face against each other. A friction member 25 constituted by winding rubber, etc., around it is arranged on the bar type roller member 20 by corresponding with a carrier standard line K of the sheet carrier passage and the roller member 19 on the opposite side, and rotation of the roller members is transmitted to the bar type roller member through the friction member 25. Consequently, in the case where nip pressure is low against the standard line of a small size sheet and the side part on the opposite side, precise carrier work is imparted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conveying roller device arranged in a sheet conveying path of an image forming apparatus such as an electrophotographic copying machine, and more particularly, when a pinch roller is formed of a round bar member, The present invention relates to a device that rotates a pinch roller in accordance with rotation so that a paper conveying action can be performed in a good condition even when a nip pressure on the paper is not uniformly set between the roller members.

[0002]

2. Description of the Related Art In an image forming apparatus such as an electrophotographic copying machine or a printer, a sheet is fed from a sheet feeding member such as a sheet feeding tray arranged in a sheet feeding section and a conveying roller device provided in a sheet conveying path is used. It constitutes a means for conveying toward the image recording unit. Examples of the conveying roller device arranged in the sheet conveying path of the image forming apparatus include, for example, the actual developing machine 64-430.
As disclosed in Japanese Laid-Open Patent Publication No. 38-38135 and Japanese Utility Model Laid-Open No. 3-23135, two pinch rollers and a driving roller, which are arranged to face each other, are provided in a skewered manner on a shaft. Things are used. As shown in the above-mentioned conventional example, when the nip pressure is to be set between both roller members by supporting with bearings on both sides in the width direction of the sheet conveying path and providing biasing means on the shaft of the pinch roller. However, there is a problem that the nip pressure is different between the central portion and the side portion of the sheet conveying path due to the curved shaft.

In view of this, in the above-mentioned conventional example, a means is provided for enabling the sheet to be effectively conveyed even when the shaft of the conveying roller device is curved and the nip pressure of the roller member at the central portion is reduced. ing. For example, in the example disclosed in Japanese Utility Model Application Laid-Open No. 64-43038, two roller members, a drive roller and a pinch roller, have a large diameter at the center of the paper transport path and a small diameter at the side of the paper transport path. In addition, even when the shaft is curved, it is possible to favorably feed the paper. In the example disclosed in Japanese Utility Model Laid-Open No. 3-23135, the roller member located at the center of the paper transport path is made of a material having a high hardness, and the roller members located at the sides of the paper transport path have a low hardness. It is disclosed to use a member constituted by members. By using the roller member having the above-described configuration, when the pinch roller is pressed against the drive roller, even if the roller shaft of the pinch roller is curved, the nip pressure in the width direction of the paper is kept constant. The value can be maintained, and the sheet is prevented from being skewed (diagonal feed).

Further, as shown in the above-mentioned conventional example, instead of providing two roller devices arranged to face each other in a skewered manner with respect to the axis of the pinch roller, the pinch roller has a round bar shape. It has been proposed to use a member to simplify the structure of the transport roller device. The transport roller device is configured, for example, as shown in FIG. 4, and the paper transport device 5 provided for the paper transport path 1 is provided.
Is used by arranging a conveyance roller device at a predetermined interval in the paper conveyance direction. In the paper transport device, each transport roller device 6, 7,
A driving roller 10 having a roller member skewered with respect to the driving shaft and a pinch roller having a round bar shape are arranged so as to face each other, and a mechanism for carrying a sheet is sandwiched between the two members. ing. Further, in the sheet conveying device 5, particularly in the conveying roller device 10 that strongly exerts a sheet conveying action, the drive roller 11 and the rod-shaped roller member 2 are used.
The nip pressure between 0 is set strongly so that the paper feeding operation can be performed in a good state. In order to set the nip pressure in the carrying roller device, a spring or the like is arranged at the shaft end portion of the rod-shaped roller member so that the rod-shaped roller member is the roller member of the drive roller, as in the case of the conventional carrying roller device. Means can be provided for pressing against.

[0005]

However, as shown in FIG. 4, when the means for urging the pinch roller against the driving roller is constructed, the rod-shaped roller member 20 is arranged so as to face the driving roller. Then, due to the bending of the shaft, there arises a problem that the nip pressure of the corresponding portion of the rod-shaped roller member is not uniform with respect to each of the roller members 15 to 19 of the drive roller. For example, as shown in FIG. 5, when the drive roller 11 is provided as a plurality of roller members 15 to 19 with respect to the drive shaft 12, the rod-shaped roller member 20 is biased by a spring or the like at the end of the shaft. When the means (not shown) is provided and the means for pressing the drive roller is configured, the rod-shaped roller member 20 is in a curved state as illustrated. Further, with respect to the roller member provided on the drive roller, in the portion corresponding to the roller member of the rod-shaped roller member, the portions on both sides of the sheet conveying path exert a large nip pressure, but in the central portion of the sheet conveying path, the rod-shaped member is rod-shaped. The roller member separates from the roller member, and the sheet cannot be nipped.

Therefore, in the above-described sheet conveying device, when the reference line K is set on one side of the sheet conveying path to form a side registration type sheet conveying device, the maximum size of A3 size which can be conveyed is set. Since the sheet is conveyed by the roller members 15 and 19 on both sides in the width direction of the sheet conveying path in a state where a large nip pressure is applied, an accurate conveying action is given even when the sheet is hardly nipped in the central portion of the sheet. The paper does not skew. On the other hand, in the case of a small size sheet such as A4 size, the roller member 15 on the reference line K side sets a large nip pressure between the roller member 15 and the pinch roller, but the roller member 17 where the other end portion of the sheet is located. Then, the sheet only contacts the roller member, which makes it difficult for the roller member to carry the sheet. In particular, since the pinch roller is made of a metal rod-shaped member, it is difficult to rotate the rod-shaped roller member accurately even if it comes into contact with the roller member if the surface of the rod-shaped roller member is configured to be a smooth surface. There are many cases. Therefore, a small-sized sheet has a problem that the rate of occurrence of skew becomes high because the conveying action is performed only on the side portion on the reference line side. Further, in the conveyance roller device using the rod-shaped roller member, it may be difficult to rotate the pinch roller even if the rotation of the roller member is made to follow, so that a small-sized sheet may be formed between the drive roller and the rod-shaped roller member. In the nipped state, only the roller member of the driving roller exerts the conveying action on the sheet, and the rod-shaped roller member does not rotate, which causes a problem that the sheet conveying action is not performed well.

In order to solve the above problems,
For example, as shown in the publication of the above-mentioned conventional example, the roller member arranged in a skewered shape on the shaft of the drive roller is made of a material having a large hardness in the central portion and a material having a small hardness at both end portions. be able to. Further, it is possible to deal with the problem that the nip pressure in the width direction of the paper is different by forming the roller member with a large diameter in the central portion and with a small diameter in both end portions. However, by configuring the roller members provided on the drive shaft to have different properties, it is necessary to prepare roller members of different sizes and types at the time of manufacturing the drive roller and fix the roller members to their corresponding positions with respect to the shaft. Therefore, there is a problem that the manufacturing cost of the drive roller is increased. Providing the drive roller as described above also has a great influence on the manufacturing cost of the image forming apparatus. Further, when using a rod-shaped roller member having a round rod shape in correspondence with the drive roller in which the roller member is arranged in a skewered shape, the pinch roller is a rigid body. It is required to develop a roller member having a property different from that of the constructed device, and there are many problems that need to be solved before being incorporated into an actual image forming apparatus.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to solve the problem of the sheet conveying action in a conveying roller device constituted by arranging a pin-shaped pinch roller in a round bar so as to face a driving roller provided with a roller member in a skewered shape on a driving shaft. By arranging a means for increasing the frictional force of the drive roller against the roller member with respect to the pinch roller, by rotating the pinch roller following the drive roller even when conveying a small size sheet. An object of the present invention is to provide a sheet conveying device of an image forming apparatus that can exert a conveying action on a sheet in a good state.

[0009]

SUMMARY OF THE INVENTION According to the present invention, there is provided a paper transporting device in which a transport roller device for pressing a pinch roller against a drive roller to transport a paper is arranged at a predetermined interval along a paper transport path. Regarding the device. In the present invention, the drive roller is configured by providing a roller member in a skewered shape with respect to the drive shaft, the pinch roller is configured by a rod-shaped member having a circular cross section, and the pinch roller is pressed against the drive roller. The pinch roller is provided with a means for increasing frictional force at a position corresponding to the roller member of the drive roller on the outer side portion of the sheet of the smallest size to be conveyed, and pinch the rotation of the drive roller. It constitutes a means for transmitting to the roller. Further, in the present invention, the frictional force increasing means provided on the pinch roller can be configured by integrally providing rubber or the like on the outer peripheral portion of the roller member.

[0010]

As described above, when the conveying roller device is constructed by combining the means for pressing the pinch roller against the drive roller, the same roller member is attached to the drive shaft of the drive roller in a skewered shape and pinched. A means for urging the roller with a spring or the like is arranged at the end of the shaft so that a nip pressure of a predetermined value can be set between both roller members. Further, when the sheet conveying path is configured as a side registration type device, a pinch is provided with means for increasing the frictional force with respect to the rod-shaped roller member in correspondence with the roller member at the end where small size sheets are not nipped. The roller is configured to rotate following the driving roller. As the frictional force increasing means provided on the rod-shaped roller member, a member such as a rubber ring is wound around the rod-shaped roller member, or means for roughening the surface of the rod-shaped roller member is used. be able to.
Further, in the case where the paper transport path is a center registration type device, by providing means for increasing the frictional force on the surface of the rod-shaped roller member in correspondence with the roller members located at both ends of the paper transport path, Even when a small-sized sheet is conveyed in the central portion of the sheet conveying path, the rod-shaped roller member can be rotated by following the rotation of the drive roller, and the sheet conveying operation can be performed in a good state.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A sheet conveying device of an image forming apparatus of the present invention will be described with reference to the illustrated example. The example shown in FIG.
Similar to the paper transporting device of FIG. 4, a device for transporting paper along the paper transporting path 1 is configured, and the paper transporting path 1 is used in an image forming apparatus such as an electrophotographic copying machine or a printer. It can be configured as a paper transport path. In the paper conveyance path 1, a reference line K for positioning the paper at the time of conveyance is set on one side, and the conveyed paper may be a small size paper such as A4 size or an A3 size. Even a large size sheet or the like is configured as a side registration type apparatus that conveys one side surface on the reference line K in a state of being positioned. In the paper transport path 1, a plurality of transport roller devices 6, 7, 10 are arranged at predetermined intervals, and in each transport roller device, a drive roller in which roller members are arranged in a skewered shape with respect to a drive shaft, Round bar pinch roller 20
Are arranged so as to face each other, and constitute a mechanism for carrying the paper sheet while sandwiching the paper between the roller members.

Of the plurality of carrying roller devices arranged in the paper carrying path, the carrying roller devices 6 and 7 are constructed by providing driving rollers 6a and 7a with a driving shaft as a roller member. Further, as the other rod-shaped roller members 6b and 7b,
For example, a round rod-shaped member is provided in a state in which it is allowed to freely rotate via bearings arranged at both ends, and the rod-shaped roller member rotates in accordance with the rotation of the drive roller to form a conveying unit. The transport roller device 10 arranged between the transport roller devices 6 and 7 is configured to exert a strong transport force on a sheet, and is a roller that constitutes a drive roller as compared with the transport roller devices 6 and 7. This makes it possible to accurately perform the conveying operation of the members and prevent skew or the like from occurring. As shown in FIG. 2, the transport roller device 10 includes frames 2 and 3 on both sides that define a paper transport path.
On the other hand, the bearings for the drive roller 11 and the rod-shaped roller member 20 are supported via bearings, but the bearings 14 and 14a for supporting the shaft of the drive roller 11 are arranged at fixed positions. Further, bearings 21 and 21a for supporting the rod-shaped roller member 20.
Via an urging means such as a spring (not shown),
A means for pressing the rod-shaped roller member toward the drive roller is provided so that the rod-shaped roller member is allowed to move slightly in the bearing direction of the drive roller.

In the conveying roller device 10, the driving roller 11 has a driving gear 13 arranged at the end of the driving shaft 12 and constitutes a means driven by a driving mechanism arranged in the sheet conveying path. Roller members 15 to 19 are provided on the drive shaft 12 at predetermined intervals in a skewered shape, and these roller members are the same as those of a conveying roller device arranged in a sheet conveying path of a general image forming apparatus. , Made of relatively hard rubber or the like. Further, the rod-shaped roller member 20 arranged so as to face the drive roller is made of a metal round rod having a diameter of about 7 to 10 mm, but a round pipe-shaped member having a relatively large rigidity may be used. it can. The rod-shaped roller member 20 is provided with a friction member 25 at a position corresponding to the roller member 19 on the side opposite to the reference line so that the rod-shaped roller member can be accurately driven by the roller member of the driving roller. is doing. The friction member 25 provided on the rod-shaped roller member 20 can be constituted by, for example, a means for winding a rubber ring. In addition, a member having a large friction coefficient such as rubber is attached to the surface of the rod-shaped roller member integrally. It can also be configured by Further, the friction member is constituted by any means such as forming a rough surface on the surface of a metal rod-shaped roller member by knurling or forming shallow grooves in the axial direction at predetermined intervals. be able to.

When the friction member 25 is arranged at the position corresponding to the roller member on the side opposite to the reference line with respect to the rod-shaped roller member 20 as described above, the friction member 2
The portion where the roller 5 and the roller member 19 are located is, for example, a portion through which the end of a large size A3 sheet passes. In the portion where the friction member is located, a large-sized sheet is nipped between the roller member 19 and the friction member 25, and the rotation of the driving roller is transmitted to the rod-shaped roller member through the sheet, so that the conveyance roller device is configured. The conveying action on the paper is accurately exhibited. On the other hand, in the case of A4 size paper or smaller size paper, at the end portion on the reference line K side of the paper, between the roller member 15 and the bar-shaped roller member, and between the roller member 19 and the bar-shaped roller member. In the interval, the nip action is accurately exhibited even when the rod-shaped roller member is curved, but the roller member 17 is provided at the central portion in the width direction of the paper transport path.
At the position, the nip pressure has the smallest value due to the bending of the rod-shaped roller member, and at the positions corresponding to the roller members 16 and 18, the nip pressure has a relatively small value. On the other hand, if the rod-shaped roller member is made of a thick rod-shaped material, it is possible to prevent the rod-shaped roller member from bending, but in practice, if the rod-shaped roller member is not curved enough, We cannot deal with the weight of the transfer device and the driving force.

As described above, in the transport roller device of the present invention, the ability of the rotation of the roller member to be transmitted to the rod-shaped roller member via the paper is reduced, but the roller member 19 at the end is reduced.
Between the friction member 25 provided on the rod roller member 20 and
It exerts an effect of transmitting the rotation of the roller member to the rod-shaped roller member, and the rod-shaped roller member constitutes a mechanism that is driven following the rotation of the drive roller. Then, even if the nip pressure between the rod-shaped roller member 20 and the roller member 17 becomes small on the side portion of the small-sized paper opposite to the reference line,
Since the drive roller and the rod-shaped roller member are rotated in conjunction with each other, any one of the roller members with which the paper is in contact carries the paper. Therefore, even for a small size sheet, the driving roller and the rod-shaped roller member apply a uniform driving action in the width direction of the sheet. The carrying action will be imparted.

Further, the interlocking means of the rod-shaped roller member used in the conveying roller device of the present invention can be applied to a center registration type sheet conveying path. In the example shown in FIG. 3, the reference line K for transporting the paper in the paper transport path is set at the center in the width direction of the paper transport path, and both the small-sized paper and the large-sized paper have the same width. The sheet is conveyed with the center of the direction aligned with the reference line K. Therefore, a small size sheet such as an A4 size sheet is nipped between the roller members 16 and 18 on both sides of the central roller member 17 and the rod-shaped roller member, and a conveying action is given. It becomes a state. Therefore, the transport roller device 10 shown in FIG.
Then, the friction members 25 and the rod-shaped roller members 20 are made to correspond to the roller members 15 and 19 at both ends of the drive roller.
26 is provided to configure a means for causing the rod-shaped roller member to follow the rotation of the drive roller. The rod-shaped roller member 20
Like the friction members shown in FIG. 2, the friction members 25 and 26 provided in the above are provided by winding rubber or the like integrally, or by using any means such as roughening the surface of the rod-shaped roller member. Can be configured. In the transport roller device 10 shown in FIG. 3, the drive roller and the rod-shaped roller member 20 and the bearings and the drive means have the same configurations as those in FIG.
It is also set in the same manner that the sheet is placed in the sheet feeding path to carry out the sheet feeding operation.

In the example shown in FIG. 3, since a large size A3 sheet or the like passing through the sheet conveying path is subjected to the conveying action at the positions corresponding to all the roller members 15 to 19 of the driving roller, it is normal. Transport action is performed. On the other hand, a small size sheet such as A4 size is subjected to the conveying action at the roller member portion where the nip pressure is weak, but the rod-shaped roller member rotates the drive roller through the friction member portion. Since the sheet is accurately followed, the sheet does not slip with respect to the rod-shaped roller member, and the sheet-conveying action is uniformly exerted in the width direction by the roller member of the drive roller and the rod-shaped roller member. Therefore, even when the friction member is provided on the rod-shaped roller member so as to correspond to both ends of the roller member of the drive roller, the conveyance force biased in the width direction is given to the conveyed sheet. Therefore, it is possible to convey the sheet without skew or the like.

In the embodiment of the present invention, the large size paper is represented by A3 and the small size paper is represented by A4. However, the size of the paper can be any size usable in the image forming apparatus. The size can be targeted. Further, with respect to the size of the paper used in the image forming apparatus, the maximum size is set to a large size, and the minimum usable size or B5 size paper is set to a small size. Corresponding to the above, a friction member can be provided on the rod-shaped roller member. Further, as the metal material forming the rod-shaped roller member and the elastic member forming the roller member of the driving roller, the same members as those of the conveying roller device arranged in the sheet conveying path of the conventional image forming apparatus may be used. it can. The transport roller device having the above-described configuration can be applied to any transport roller device arranged in the paper transport path, and can be incorporated in any device that transports paper in addition to the image forming apparatus. You can

[0019]

As described above, the sheet conveying device of the image forming apparatus of the present invention is configured as a conveying roller device by combining means for pressing the rod-shaped roller member against the driving roller. A means for urging the driving roller by a spring or the like arranged at the shaft end of the rod-shaped roller member is arranged so that a nip pressure of a predetermined value can be set between both roller members. Further, when the sheet conveying path is configured as a side registration type device, means for increasing the frictional force with respect to the rod-shaped roller member is provided so as to correspond to the roller member at the end where the smallest size sheet is not nipped. The rod-shaped roller member can be rotated following the drive roller. Even if there is a portion where the nip pressure is weak between the roller member and the rod-shaped roller member of the drive roller, the roller member carries the action of transporting the paper that contacts either the roller member or the rod-shaped roller member. Therefore, the sheet does not slip with respect to the driving means, and the conveying action can be excellently exhibited. Therefore, the sheet conveyed in the sheet conveying path is not skewed, and the accurate conveying operation can be performed.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration of a sheet conveying device of the present invention.

FIG. 2 is an explanatory diagram showing a configuration of a transport roller device of the present invention.

FIG. 3 is an explanatory diagram of a second embodiment of the present invention.

FIG. 4 is a perspective view showing a configuration of a prior art example targeted by the present invention.

5 is an explanatory diagram showing a configuration of a transport roller device of FIG.

[Explanation of symbols]

1 paper transport path, 5 paper transport device, 6/7/1
0 transport roller device, 11 drive roller, 12
Drive shaft, 15 to 19 roller members, 20 rod-shaped roller members, 25 and 26 friction members.

Claims (2)

[Claims] 1. A paper carrying device comprising a carrying roller device for pressing a pinch roller against a driving roller and carrying out a carrying operation of a paper, arranged at a predetermined interval along a paper carrying path. A roller member is provided on the drive shaft in a skewered shape, the pinch roller is a rod-shaped member having a circular cross section, and means for pressing the pinch roller against the drive roller is formed. Is a means for increasing the frictional force at a position corresponding to the roller member of the drive roller on the outer side of the smallest size sheet to be conveyed, and constitutes a means for transmitting the rotation of the drive roller to the pinch roller. A sheet conveying device of an image forming apparatus characterized by the above. 2. The sheet of the image forming apparatus according to claim 1, wherein the frictional force increasing means provided on the pinch roller is constituted by a friction member integrally provided with rubber or the like on an outer peripheral portion of the roller member. Transport device.