JP2005145707A - Sheet conveying device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive sheet conveying device and an image forming device that allow regulation of positions in the width direction of a plurality of sheets only with a pair of conveying rollers and have high regulation capacity of the positions in the width direction of sheets. <P>SOLUTION: The sheet conveying device comprises a conveying surface forming a sheet conveying route, a reference plate having a reference surface for regulating a sheet-side end part and correcting the sheet to a predetermined position in the width direction, the conveying rollers for conveying the sheet, and obliquely feeding rollers that face and abut on the conveying rollers to form a nip and are disposed with a predetermined oblique feed angle with respect to the reference plate. The sheet conveying device rotates the sheet while applying a conveying force to the sheet with a pair of conveying roller pairs formed of the conveying rollers and the obliquely feeding rollers. Energizing members for energizing the sheet to the conveying surface are disposed on the upstream side of the conveying roller position in the sheet conveying direction and on the reference plate side than the conveying roller position. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a sheet conveying apparatus that conveys sheet materials such as paper, envelopes, and postcards in an image forming apparatus such as a printer or a copying machine.

  Some image forming apparatuses such as electrophotographic printers have a sheet conveyance path for performing automatic printing on both sides of a recording sheet such as paper. In general, such an apparatus is configured to print on the second side by printing on one side of the sheet, then inverting the sheet and transporting it again to the image forming unit. In recent years, there has been an increasing demand for reduction of paper consumption from the viewpoint of environmental protection, and there has been a demand for diversification of sheet types for second-side printing.

  Various image forming apparatuses capable of printing on both sides of a sheet have been proposed. (For example, refer to Patent Document 1). The outline of the double-sided image forming apparatus will be described below with reference to FIG.

  As shown in FIG. 9, the image forming apparatus B emits a laser L based on the obtained image information by the laser scanner 1 and irradiates the photosensitive drum 3 built in the process cartridge 2 with the laser L. Then, a latent image is formed on the photosensitive drum 3, and the latent image is developed with toner by the process cartridge 2.

  On the other hand, the recording sheets S stacked on the recording sheet stacking plate 5 are fed one by one while being separated one by one by the feeding roller 6 and the separation pad 7, and further downstream by the intermediate roller 8 and the conveying roller 9. The toner image formed on the photosensitive drum 3 is transferred by the transfer roller 4 onto the conveyed recording paper.

  Then, the recording paper S on which the unfixed toner image is formed is conveyed further downstream, the toner image is fixed by the fixing device 12 having a heat source therein, and then only one side is printed. The paper is discharged out of the apparatus by the discharge roller 14 through the discharge roller 13a.

  Next, the configuration of the apparatus for printing on both sides of the sheet will be described.

  The discharge roller 14 is configured to be forward / reverse. Here, when the trailing edge of the sheet S ′ passes through the nip formed by the intermediate paper discharge roller 13a and the intermediate paper discharge roller 13b and reaches the position indicated by the solid line in FIG. 9, the discharge roller starts a reverse operation. That is, it rotates in the direction opposite to the direction of the arrow Y that has been rotated so far.

  The sheet passing detection is performed by the sensor arm 19 and a photo interrupter (not shown) that detects the movement of the sensor arm 19. That is, when the sheet passes the sensor arm, the sensor arm is in the position of the solid line in the figure, and otherwise, it is in the position of the broken line. By detecting this difference in position with a photo interrupter, the trailing edge position of the sheet is detected, and the timing for starting the reverse operation of the discharge roller 14 is determined.

  By this reverse operation, the sheet is conveyed downward along the guide 16 and guided to a nip formed by the switch roller 15 and the intermediate paper discharge roller 13a. Thereafter, the sheet is conveyed to the intermediate paper discharge roller 13 a and reaches the intermediate roller 8 through the first conveyance roller 17 and the second conveyance roller 18. When passing through the first conveying roller 17 and the second conveying roller 18, the position of the side edge portion of the sheet is regulated by a position regulating method described later. The sheet that has reached the intermediate conveyance roller is then transferred with the transfer roller 4 in the same manner as the image formation on the first surface, and passes through the fixing roller 12 and the intermediate discharge roller 13a, and is discharged from the machine by the discharge roller 14. To be discharged.

  In such an image forming apparatus, in general, while a sheet is fed by a sheet feeding roller and conveyed by a plurality of rollers such as a transfer roller, the sheet is skewed due to misalignment of roller shafts constituting each roller pair. May be transported. Further, when a user sets a sheet on a tray such as a cassette, the sheet may be set out of the normal position in the paper width direction. If the sheet is conveyed to the image forming unit while being shifted, an image is printed at a position shifted from a desired position.

  In particular, when printing on both sides of a sheet as in the above-described conventional example, such a positional deviation of the image is likely to occur because the transport distance until printing on the second side is long. For this reason, there are many cases where a position restricting means for restricting the position of the side edge of the sheet is provided in the conveyance path in the width direction of the sheet.

  Restricts the position of the side edge of an A4 / LTR / LGL sheet (hereinafter referred to as a large sheet) and the position of the side edge of an A5 sheet (hereinafter referred to as a small sheet) The position restricting means having both methods will be described here.

  FIG. 10 is a cross-sectional view of the vicinity of the double-sided conveying roller of the sheet as viewed from the upper surface side. In FIG. 10, 21 is a guide member having a reference surface for correcting the position of the edge of the sheet and a conveyance surface that forms a conveyance path, 21a is a reference surface for a large sheet, 21b is a reference surface for a small sheet, 21c is a conveyance surface for large sheets, and 21d is a conveyance surface for small sheets. Reference numeral 22 denotes a pair of large sheet conveying rollers that also serves as a refeeding unit, and reference numeral 23 denotes a pair of small sheet conveying rollers. The large sheet conveying roller pair and the small sheet conveying roller pair have substantially the same configuration, and are driven to rotate by being obliquely pressed against the large and large sheet conveying driving roller 22a and the small sheet conveying driving roller 23a that are driven and rotated. A large sheet skew feeding roller 22b and a small sheet skew feeding roller 23b are provided. The large sheet inclined feeding roller 22b and the small sheet inclined feeding roller 23b are configured to be in pressure contact with the large sheet conveying driving roller 22a and the small sheet conveying driving roller 23a by springs (not shown) provided for the respective sheets. Yes. For this reason, the two pairs of conveying rollers have a conveying force for feeding the sheet obliquely in the direction shown in the drawing. Further, the large sheet and small sheet conveying roller pair is disposed at a predetermined distance in the vicinity of the reference surface of the large sheet and the small sheet in order to prevent the sheet from buckling due to an oblique conveying force.

  The large sheet is conveyed so as to be in contact with the reference surface 21a of the large sheet, and the small sheet is conveyed so as to be in contact with the reference surface 21b of the small sheet. The position of is regulated.

  As shown in the conventional example, in order to increase the number of compatible sheet types for second-side printing, the reference surface for position correction for the corresponding sheet type and the vicinity thereof to prevent buckling of the sheet with the feeding force sent obliquely It was necessary to arrange a pair of conveying rollers.

  On the other hand, in order to provide an image forming apparatus capable of forming a double-sided image at a low cost, the sheet is obliquely fed in the direction shown in the drawing by using only the small sheet conveying roller pair 23 as shown in the conventional example, and the large sheet reference A configuration in which the sheet 21 is conveyed so as to be in contact with the surface 21a and the reference surface 21b of the small sheet and the position thereof is regulated is conceivable.

Note that such position regulating means may be provided not only on a printer having automatic duplexing but also on a conveyance roller located between the paper feed roller and the image forming unit. This is mainly to correct a deviation from the normal position of the sheet when the user sets the sheet.
Japanese Patent Laid-Open No. 9-100056 (FIG. 1)

  However, in order to provide an image forming apparatus capable of forming a double-sided image at low cost, the sheet is obliquely fed in the direction shown in the figure with only the small sheet conveying roller pair 23 shown in FIG. If the sheet is conveyed so as to be in contact with the reference surface 21b of the sheet and the position thereof is regulated, there are the following problems.

  1. When trying to correct the position by transporting a large sheet, since the distance from the large sheet reference surface 21a to the pair of small sheet transport rollers 23 is large, the rigidity of the sheet is lost, and the transport force for feeding the sheet in the direction shown in FIG. When the large sheet is conveyed so as to contact the reference surface 21a, the sheet may be buckled and jammed as shown in FIG.

  2. When the sheet is conveyed by only the small sheet conveying roller pair 23 when the positional deviation in the width direction of the sheet is large or when the skew feeding amount is large, as shown in FIG. Due to the frictional resistance with the large sheet, a moment M21e that tries to rotate the leading end of the large sheet away from the reference surface 21a about the sheet pressure contact position of the small sheet conveying roller pair 23 acts, and the upstream end of the reference surface 21a The rear edge of the sheet rotates toward As shown in FIG. 12B, in this rotation operation, the sheet comes into contact with the upstream end portion of the reference surface 21a, and the front end of the sheet rotates reversely by the reaction force to align with the reference surface 21a.

  Since the sheet position is regulated while the sheet trailing edge is rotated toward the upstream side and then the sheet leading edge is rotated, the sheet regulation takes time, and the sheet width direction position may not be sufficiently regulated.

  The present invention has been made to solve the above-described problems of the prior art, and an object of the present invention is to make it possible to regulate the position of a plurality of sheets in the width direction by using only a pair of conveying rollers, and the width of the sheet. An object of the present invention is to provide an inexpensive sheet conveying apparatus and image forming apparatus having a high regulation ability with respect to the direction position.

  In order to achieve the above object, a representative invention according to the present application includes a reference surface having a conveyance surface that forms a sheet conveyance path and a reference surface that regulates the sheet to a predetermined width direction position by regulating a sheet side end. A plate, a conveying roller that conveys the sheet, and a skew feeding roller that is in contact with the conveying roller to form a nip and is disposed at a predetermined oblique feeding angle toward the reference plate. In a sheet conveying apparatus that rotates a sheet while applying a conveying force to the sheet by a pair of rollers composed of a roller and a skew feeding roller, the conveying roller position is upstream of the conveying roller position and in the sheet conveying direction. Further, an urging member for urging the sheet toward the conveying surface is provided on the reference plate side.

  According to the above invention, since the sheet is pressed by the urging member positioned in the vicinity of the reference surface with respect to the conveying roller pair, the sheet is buckled even when the distance from the reference surface of the sheet to the sheet conveying roller pair is large. Therefore, it is possible to regulate the position in the width direction of a plurality of sheets with only a pair of conveying rollers.

  Further, by setting the urging force of the urging member so as to eliminate the moment to rotate the front end of the sheet away from the reference surface, the rear end of the sheet is prevented from rotating toward the upstream side. Even in the configuration with only the conveying roller pair, it is possible to provide an inexpensive sheet conveying apparatus and image forming apparatus having a high regulation ability with respect to the position in the width direction of the sheet.

  As described above, according to the present invention, it is possible to provide an inexpensive sheet conveying apparatus and image forming apparatus having a high regulation ability with respect to the position in the width direction of the sheet.

  Exemplary embodiments of the present invention will be described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. Absent.

(Embodiment 1)
An example in which the sheet conveying apparatus according to the first embodiment of the present invention is used in a laser printer will be described.

  FIG. 1 is a side sectional view of an image forming apparatus using a sheet conveying apparatus according to the first embodiment. 2 is a cross-sectional view of the sheet conveying apparatus according to the first embodiment as viewed from the upper surface side, FIG. 3 is a perspective view of FIG. 2, and FIG. 4 is a diagram illustrating the position restriction of the first embodiment. is there.

  In FIGS. 1, 2, and 3, reference numeral 21 denotes a guide member having a reference surface for correcting the position of the edge of the sheet and a conveying surface that forms a conveying path, 21a being a reference surface for a large sheet, and 21b being a reference for a small sheet. 21c is a large sheet conveying surface, and 21d is a small sheet conveying surface. Reference numeral 31 denotes a pair of conveying rollers for conveying a large sheet and a small sheet that also serve as a refeeding unit. The sheet conveyance driving roller 31a that rotates is driven, and the sheet conveyance roller 31b that is driven to rotate while being obliquely pressed against the sheet conveyance driving roller 31a. The sheet feeding roller 31b is configured to be in pressure contact with the sheet conveyance driving roller 31a by a spring (not shown) provided for each. For this reason, the conveyance roller pair 31 has a conveyance force for feeding a large sheet and a small sheet obliquely in the illustrated direction.

  Reference numeral 32 denotes an urging member that urges the large sheet toward the large sheet conveying surface 21c. The urging member 32 is located on the upstream side in the sheet conveying direction from the position of the conveying roller pair 31 and on the reference surface 21 a side of the large sheet from the position of the conveying roller pair 31. The urging member 32 is made of an elastic material, and applies an urging pressure to the large sheet by elastic bending. A sheet abutting portion 32 a abuts against the large sheet of the urging member 32. The sheet contact portion 32a has a small coefficient of friction and a smooth surface. Therefore, the conveyance resistance generated by the urging force of the urging member 32 is mainly a frictional force generated between the large sheet and the conveyance surface 21c.

  Other reference numerals in FIGS. 1, 2, and 3 are the same as those in the conventional example in FIG.

  As shown in FIG. 2, in the present embodiment, the small sheet is conveyed so as to abut on the reference surface 21b of the small sheet and the position of the small sheet is regulated by the conveyance force that feeds the paper obliquely by the conveyance roller pair 31. Since the conveyance roller pair 31 and the small sheet reference surface 21b are close to each other, the sheet does not buckle.

  Further, as shown in FIG. 4, the large sheet is conveyed by the conveying roller pair 31 so as to abut on the reference surface 21a of the large sheet, and at this time, the large sheet side is provided by the biasing member 32 disposed on the reference surface 21a side of the large sheet. The rigidity of the end portion is maintained and the seat is prevented from buckling.

Since the urging member 32 urges the large sheet, the leading edge of the large sheet is directed toward the reference surface 21a with the frictional force generated between the large sheet and the conveying surface 21c around the sheet pressing position of the conveying roller pair 31. The moment M32 which tries to rotate is applied.
At this time, a moment M21e that acts to rotate the leading end of the large sheet away from the reference surface 21a about the sheet pressing position of the pair of conveying rollers 31 acts due to the sliding resistance between the conveying path 21e and the large sheet.

  Since the urging force of the urging member 32 is set so that moment M32 ≧ moment M21e, the large sheet moves toward the reference surface 21a in the movement direction almost close to parallel movement by the oblique feeding force by the conveying roller pair 31. While being conveyed in the conveying direction. Then, after the side edge of the large sheet is completely along the reference surface 21a (see FIG. 6B), the sheet is conveyed in the conveying direction by the cooperative action of the conveying force of the conveying roller pair 31 and the reaction of the reference surface 21a. It is conveyed straight to.

  As described above, according to this embodiment, since the sheet is pressed by the biasing member positioned near the reference surface with respect to the conveyance roller pair, even when the distance from the sheet reference surface to the sheet conveyance roller pair is large. Sheet buckling does not occur, and the position in the width direction of a plurality of sheets can be regulated with only a pair of conveying rollers.

  Further, by setting the urging force of the urging member so as to eliminate the moment to rotate the front end of the sheet away from the reference surface, the rear end of the sheet is prevented from rotating toward the upstream side. Even in the case of only the pair of conveying rollers, it is possible to increase the sheet width direction position regulating ability.

  As is apparent from the above description, according to the present embodiment, it is possible to provide an inexpensive sheet conveying apparatus and image forming apparatus having high sheet width direction position regulating capability.

(Embodiment 2)
The image forming apparatus according to the second embodiment is applied to the sheet conveying apparatus having the cross section of FIGS. 1 and 2 as in the first embodiment, but a sheet contact portion that contacts the large sheet of the urging member 32. Is different from the first embodiment.

  FIG. 5 shows an enlarged side sectional view of an image forming apparatus using the sheet conveying apparatus according to the second embodiment in the present embodiment, and FIG. 6 shows a perspective view of FIG.

  Reference numeral 32b denotes a sheet contact portion that contacts the large sheet of the urging member 32. The sheet contact portion 32b is formed by extending a substantially linear contact convex shape in which the contact portion of the sheet is reduced in a direction substantially perpendicular to the conveyance direction. It has become. Therefore, on the upper surface of the large sheet, the conveyance resistance increases substantially in the conveyance direction, and the movement resistance decreases in the sheet width direction. For this reason, since the moment 32 can be increased and the movement resistance in the sheet width direction is small, the leading edge of the large sheet tends to rotate toward the reference surface 21a around the sheet pressure contact position of the conveying roller pair 31. For this reason, it is possible to have a higher sheet skew feeding capability.

  In this embodiment, it is possible to provide a sheet conveying apparatus having a higher position regulating capability in the sheet width direction while preventing the sheet from buckling.

(Embodiment 3)
The image forming apparatus according to the third embodiment is applied to the sheet conveying apparatus having the cross section of FIGS. 1 and 2 as in the first embodiment, but the sheet abutting portion that abuts against the large sheet of the urging member 32. Is different from the first and second embodiments.

  FIG. 7 shows an enlarged side sectional view of an image forming apparatus using the sheet conveying apparatus according to the third embodiment in the present embodiment, and FIG. 8 shows a perspective view of FIG.

  A sheet abutting portion 32c abuts against a large sheet of the urging member 32. The sheet abutting portion 32c is a rotatable roller having a substantially cylindrical shape extending in a direction substantially perpendicular to the conveying direction. Therefore, on the upper surface of the large sheet, the conveyance resistance increases substantially in the conveyance direction, and the movement resistance decreases in the sheet width direction. For this reason, since the moment 32 can be increased and the movement resistance in the sheet width direction is small, the leading edge of the large sheet tends to rotate toward the reference surface 21a around the sheet pressure contact position of the conveying roller pair 31. For this reason, it is possible to have a higher sheet skew feeding capability.

  In addition, the introduction of the sheet can be facilitated by the fact that the diameter of the central part in the axial direction is larger than the diameter of the end part in the axial direction.

  In this embodiment, it is possible to provide a sheet conveying apparatus having a higher position regulating capability in the sheet width direction while preventing the sheet from buckling.

1 is a side sectional view of an image forming apparatus using a sheet conveying device according to a first embodiment of the present invention. Sectional drawing seen from the upper surface side about the sheet conveying apparatus which concerns on the 1st Embodiment of this invention. 1 is a perspective view showing a sheet conveying apparatus according to a first embodiment of the present invention. FIG. 3 is an explanatory diagram illustrating a state of sheet conveyance in the first embodiment of the present invention. FIG. 6 is an enlarged side sectional view of an image forming apparatus using a sheet conveying device according to a second embodiment of the present invention. FIG. 6 is a perspective view showing a sheet conveying apparatus according to a second embodiment of the present invention. FIG. 9 is an enlarged side sectional view of an image forming apparatus using a sheet conveying device according to a third embodiment of the present invention. FIG. 10 is a perspective view illustrating a sheet conveying apparatus according to a third embodiment of the present invention. FIG. 6 is a side cross-sectional view of an image forming apparatus using a sheet conveying apparatus according to a conventional sheet conveying apparatus. Sectional drawing seen from the upper surface side about the sheet conveying apparatus which concerns on the conventional sheet conveying apparatus. Explanatory drawing which shows the mode of the conventional sheet conveyance. Explanatory drawing which shows the mode of the conventional sheet conveyance.

Explanation of symbols

21 Guide member 21a Large sheet reference surface 21b Small sheet reference surface 21c, 23e Large sheet conveyance surface 21d Small sheet conveyance surface 31 Conveying roller pair 31a Conveying roller 31b Slope feeding roller 32 Biasing member 32a, 32b, 32c Sheet Contact part

Claims (8)

A conveyance surface that forms a sheet conveyance path, a reference plate that regulates the sheet side edge and corrects the sheet to a predetermined width direction position, a conveyance roller that conveys the sheet, and the conveyance roller A pair of conveying rollers each having a conveying roller and an inclined feeding roller, which has a slant feeding roller disposed in contact with each other to form a nip and a predetermined oblique feeding angle toward the reference plate. In a sheet conveying apparatus that rotates a sheet while applying a conveying force to the sheet,
A sheet conveying apparatus comprising an urging member for urging the sheet toward the conveying surface on the upstream side in the sheet conveying direction from the conveying roller position and on the reference plate side from the conveying roller position.   The sheet conveying apparatus according to claim 1, wherein the sheet conveying apparatus is configured to have a frictional resistance force between the sheet and the conveying surface by the urging force of the urging member.   The sheet conveying apparatus according to claim 1, wherein the friction resistance is configured to be smaller than a conveying force of a pair of conveying rollers constituted by the conveying roller and the obliquely feeding roller.   The sheet conveying apparatus according to claim 1, wherein the biasing member is made of an elastic material.   The sheet conveying apparatus according to claim 1, wherein a friction coefficient of a sheet contact surface portion of the urging member is small and a surface is smooth.   6. The sheet conveying apparatus according to claim 5, wherein a convex shape having a substantially line contact is formed on the sheet in a substantially sheet width direction at a sheet contact surface portion of the urging member.   The sheet conveying apparatus according to claim 5, wherein a roller that is rotatable in a substantially sheet width direction is formed on a sheet contact surface portion of the urging member. The sheet conveying apparatus according to claim 7, wherein a diameter of the central portion in the axial direction of the roller is larger than a diameter of the end portion in the axial direction.

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