JP3943996B2 - Sheet conveying apparatus and image forming apparatus provided with the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sheet conveying apparatus and an image forming apparatus provided with the sheet conveying apparatus, and in particular, after reversing a sheet having an image formed on the surface thereof by an image forming unit, the sheet is formed again to form an image on the back surface of the sheet. The present invention relates to what is conveyed to the forming unit.
[0002]
[Prior art]
In a conventional image forming apparatus such as a copying machine or a printer, a double-sided image in which an image is formed on the first surface (front surface) of the sheet and then the sheet is reversed to form an image on the second surface (back surface) of the sheet. There is an image forming apparatus capable of forming.
[0003]
Such an image forming apparatus includes a sheet conveying device that reverses the sheet on which the image is formed on the first surface in the image forming unit and conveys the sheet again to the image forming unit. In the sheet conveying apparatus, for example, the reversal of the sheet on which the image is formed on the first surface is performed by switching back the sheet by the switchback conveying unit.
[0004]
By the way, in such a sheet conveying apparatus, in order to accurately form an image on the second surface of the switchback conveyed sheet, for example, the position in the direction orthogonal to the sheet conveying direction (hereinafter referred to as the width direction) is regulated. The position of the sheet in the width direction is restricted by moving the restricting means in the width direction in accordance with the size of the sheet to be switched back.
[0005]
As another method, the sheet that has been transported in the switchback is obliquely fed toward the reference wall while being sandwiched between the conveyance roller and the oblique feeding roller in the oblique feeding unit, and one end of the sheet is pressed against the reference wall. There is a method of regulating the position in the width direction of the sheet by one-side reference conveyance while conveying.
[0006]
[Problems to be solved by the invention]
However, in the conventional sheet conveying apparatus and the image forming apparatus including the conventional sheet conveying apparatus that regulate the position in the width direction of the sheet by such a method, the position in the width direction of the regulating unit is moved by a predetermined amount according to the sheet size. Since the driving method requires a driving means, the structure is complicated and the cost is increased as compared with the method of regulating the sheet position by one-side reference conveyance.
[0007]
Also in the method of regulating the sheet position by one-side reference conveyance, for example, the re-conveyance passage for re-conveying the sheet toward the image forming unit is in the vertical direction, and the sheet conveyance speed at the time of switchback is obliquely fed. When it is faster than the sheet conveying speed of the conveying unit, the end of the sheet not nipped by the conveying roller and the oblique feeding roller is lower than the nipped sheet due to its own weight and the conveying speed difference, and the sheet moves to the reference wall side. It will tilt.
[0008]
When the sheet is tilted in this way, when the position in the width direction of the sheet is restricted, the tilted sheet must be pressed against the reference wall, and in this case, the sheet is surely pressed against the reference wall. In this case, it is necessary to increase the skew feeding force as compared with the case of pressing a non-tilted sheet.
[0009]
Here, since the oblique feeding force varies depending on the friction coefficient between the conveyed sheet and the conveying roller, in order to be able to press any type of sheet against the reference wall, the friction coefficient with the conveying roller is the largest. The skew feeding force must be determined based on a small sheet.
[0010]
However, when the skew feeding force is determined based on the sheet having the smallest friction coefficient with the conveyance roller as described above, a sheet having a large friction coefficient with the conveyance roller or a sheet having a light weight is placed on the reference wall in the width direction. Since the sheet is strongly pressed, the sheet buckles and wrinkles occur.
[0011]
Next, such a problem will be specifically described with reference to FIG.
[0012]
In the figure, reference numeral 16a denotes a skew feeding roller, and 16d denotes a skew feeding roller that sandwiches the sheet together with the skew feeding roller 16a. The sheet S on which an image is formed on the first surface discharged by a discharge roller (not shown) It contacts the inclined feeding roller 16a. Here, since the sheet conveying speed of the discharge roller is faster than the sheet conveying speed of the skew feeding roller 16a, the sheet S is placed on the side (right side) of the sheet S at the moment when the sheet S is sandwiched between the skew feeding roller 16a and the skew feeding roller 16d. The brake is applied.
[0013]
As a result, the sheet S rotates counterclockwise in FIG. Further, since the left side of the sheet S is not held, the left side tends to hang down due to the weight of the sheet S at the moment when the trailing edge of the sheet S is removed from the discharge roller.
[0014]
Then, the sheet S conveyed in the state of lower left like S1 shown in the second from the top is obliquely fed in the direction of the lateral registration reference member 16c by the skew roller 16d and the oblique feeding roller 16a. However, when the sheet is conveyed in such a slanted state, even if the sheet S is fed obliquely, the states of S2 and S3 shown in the third and fourth from the top depending on the type of the sheet Thus, it is impossible to completely abut against the lateral resist reference member 16c and the lateral resist guide 16b.
[0015]
Here, in order to completely abut all types of sheets against the lateral registration reference member 16c and the lateral registration guide 16b, the oblique feeding force by the skew roller 16d and the oblique feeding roller 16a may be increased. If the sheet S is too strong, for example, when the sheet S is a sheet having a small coefficient of friction with the skew feeding roller 16a, a sheet having a small sag due to its own weight, such as a thin sheet or a small sheet, the sheet S is directed to the lateral resist reference member 16c. The paper is strongly pressed, and paper wrinkles due to buckling occur.
[0016]
As described above, when the oblique feeding force is increased, the sheet S can be completely abutted against the lateral resist reference member 16c. However, depending on the type of the sheet S, paper wrinkles due to buckling may occur.
[0017]
Note that, when the oblique feeding force is lowered in order to avoid the buckling of the sheet, the sheet S cannot be reliably pressed against the lateral registration reference member 16c depending on the type of the sheet. Problems such as skewing occur.
[0018]
Further, in order to eliminate the brake on the right side of the sheet S, if the sheet conveyance speed of the skew feeding roller 16a is made faster than the sheet conveyance speed of the discharge roller, the fixing unit has a conveyance force of the sheet S more than the skew feeding roller 16a. Therefore, the skew feeding force required for abutting against the lateral resist reference member 16c cannot be obtained, and problems such as misalignment of the second image and skewing occur.
[0019]
Therefore, the present invention has been made in view of such a current situation, and a sheet conveying apparatus capable of preventing sheet buckling, misalignment, and skew when refeeding, and an image including the sheet conveying apparatus. An object of the present invention is to provide a forming apparatus.
[0020]
[Means for Solving the Problems]
The present invention is for conveying a sheet. Formed vertically A conveying path, a skew feeding means provided in the conveying path for obliquely feeding a sheet passing through the conveying path, and a side edge of the sheet provided in the conveying path and obliquely fed by the skew feeding means. A reference member that contacts and positions in a direction perpendicular to the conveyance direction of the sheet, and is provided in the conveyance path; When the sheet is obliquely fed by the skew feeding means, the drooping of the side end portion opposite to the one side end of the sheet is regulated. A regulating member that presses a side end opposite to one side end of the sheet. The regulating member is driven and rotated by the sheet passing through the conveyance path and is movably provided in the thickness direction of the sheet, and presses the sheet with a force that does not hinder the oblique feeding of the sheet by the skew feeding means. It is characterized by this.
[0021]
The present invention also provides a conveyance path formed in the vertical direction for conveying a sheet, a skew feeding means provided in the conveyance path for obliquely feeding a sheet passing through the conveyance path, and provided in the conveyance path. A reference member that contacts one side edge of the sheet that has been obliquely fed by the skew feeding means and that is positioned in a direction perpendicular to the conveyance direction of the sheet, and is provided in the conveyance path. A regulating member that presses the side end opposite to the one side end of the sheet so as to regulate the sagging of the side end opposite to the one side end of the sheet when being obliquely fed; The regulating member is formed of a plate-like elastic member that is movable in the thickness direction of the sheet and that presses a sheet passing through the conveyance path to a conveyance guide constituting the conveyance path, and the skew feeding unit With a force that does not prevent the sheet from being It is characterized in that for pressing the door. In the invention, it is preferable that the conveyance path is a re-conveyance path that conveys the sheet to the image forming unit again so as to form an image on the back surface of the sheet having an image formed on the front surface by the image forming unit. It is what.
[0022]
Further, the invention is characterized in that the sheet fed obliquely by the oblique feeding means passes through the conveyance path downward.
[0024]
Also, the present invention provides the regulating member as the skew feeding means. In the vertical direction It arrange | positions in the same height position, It is characterized by the above-mentioned.
[0028]
According to the present invention, an image forming apparatus includes an image forming unit and any one of the sheet conveying apparatuses described above.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0030]
FIG. 1 is an overall configuration diagram of a color laser printer as an example of an image forming apparatus including a sheet conveying device according to a first embodiment of the present invention.
[0031]
In the figure, reference numeral 50 denotes a color laser printer, and 51 denotes a color laser printer main body (hereinafter referred to as a printer main body). The printer main body 51 has an image forming unit 52 for forming an image on a sheet, and a sheet feeding unit. A paper unit 8, a sheet conveying device 9 that conveys a sheet fed from the paper feeding unit 8 to the image forming unit 52, and a fixing unit 10 that fixes an image formed on the sheet are provided.
[0032]
Here, the image forming unit 52 is arranged in the vertical direction, and each of the photosensitive drums 1a to 1d and the photosensitive drums 1a to 1d, which are image carriers that support toner images of four colors of yellow, magenta, cyan, and black. Charging means 2a to 2d, which are arranged around 1d along the rotation direction and uniformly charge the surface of the photosensitive drum, and irradiate a laser beam based on image information to form an electrostatic latent image on the photosensitive drum. Exposing means 3a to 3d for forming the toner, developing means 4a to 4d for making the toner image adhere to the electrostatic latent image and developing the toner image, and cleaning means 6a to 6a for removing the toner remaining on the surface of the photosensitive drum after transfer. 6d etc. are provided.
[0033]
In this embodiment, the photosensitive drums 1a to 1d, the charging units 2a to 2d, the developing units 4a to 4d, and the cleaning units 6a to 6d are integrally formed as a cartridge to form process cartridges 7a to 7d. Yes.
[0034]
In addition, the photosensitive drums 1a to 1d as image carriers are configured by applying an organic photoconductor layer (OPC) to the outer peripheral surface of an aluminum cylinder. Further, both end portions of the photosensitive drums 1a to 1d are rotatably supported by flanges, and a driving force is transmitted to one end portion from a driving motor (not shown) to counterclockwise (in the direction of the arrow in the figure). ) Is driven to rotate.
[0035]
The charging means 2a to 2d are conductive rollers that abut on the surface of the photosensitive drum and uniformly charge the surface of the photosensitive drum by applying a charging bias voltage by a power source (not shown). It is. The exposure means 3a to 3d have a polygon mirror, and image light corresponding to an image signal is irradiated to the polygon mirror from a laser diode (not shown).
[0036]
The developing means 4a to 4d are adjacent to the toner storage portions 4a1 to 4d1 that store toners of black, cyan, magenta, and yellow, respectively, and are driven to rotate by a driving unit (not shown) and developed (not shown). It is composed of developing rollers 4a2 to 4d2 that perform development by applying a developing bias voltage from a bias power source.
[0037]
In addition, transfer members 5a to 5d that sandwich the transfer conveyance belt 9a are provided together with four photosensitive drums 1a to 1d inside a transfer conveyance belt 9a that conveys a sheet, which will be described later.
[0038]
Here, the transfer members 5a to 5d are connected to a power supply for transfer bias (not shown), and positive charges are applied to the sheet from the transfer members 5a to 5d via the transfer conveyance belt 9a. Yes. By applying the transfer bias in this manner, the negative color toner images on the photosensitive drum 1 are sequentially transferred to the sheet in contact with the photosensitive drum 1 so that a multicolor image is formed. It has become.
[0039]
The paper feed unit 8 includes a paper feed cassette 8a, a multi-feed tray 8b, a multi-feed unit 8c, a registration roller pair 8d, and the like. Here, the paper feed cassette 8a stores a plurality of sheets and is loaded on the bottom of the printer main body, and the multi-feed tray 8b is usually stored in the front of the printer main body, but when used, FIG. It is opened as shown in Fig. 2, and a plurality of sheets are stacked.
[0040]
When forming an image, sheets are separated and fed one by one from the sheet feeding cassette 8a by the pickup roller 8a1, and the sheet conveying device 9 is conveyed by the cassette conveying roller 8a2 and the registration roller pair 8d that conveys the sheet at a predetermined timing. It is designed to be conveyed.
[0041]
When feeding sheets from the multi-feed tray 8b, the sheets stored in the multi-feed tray 8b are separated and fed one by one by the multi-pickup roller 8c1, and the multi-conveying roller 8c2 and the registration roller pair 8d are fed. Is conveyed to the sheet conveying device 9. Note that separation and conveyance of sheets in the paper feed cassette 8a and the multi-feed unit 8c are performed by a feed motor (not shown) provided in the paper feed unit 8 via a gear drive train.
[0042]
The sheet conveying apparatus 9 includes a transfer conveying belt 9a as a sheet carrier that is stretched and supported by a driving roller 9b and driven rollers 9c to 9e, and is disposed to face all the photosensitive drums 1a to 1d. ing. Here, the transfer conveyance belt 9a electrostatically attracts the sheet to the outer peripheral surface facing the photosensitive drums 1a to 1d, and circulates and moves by the driving roller 9b so that the sheet contacts the photosensitive drums 1a to 1d. It is like that. The sheet is conveyed to the transfer position by the transfer conveyance belt 9a by being electrostatically attracted to the transfer conveyance belt 9a that circulates in this way, and the toner image on the photosensitive drum 1 is transferred.
[0043]
Reference numeral 9f denotes an adsorption roller that is disposed at the most upstream position of the transfer conveyance belt 9a, holds the sheet together with the transfer conveyance belt 9a, and adsorbs the sheet to the transfer conveyance belt 9a. By applying a voltage to the roller 9f, an electric field is formed between the opposed driven roller 9c, and dielectric polarization is generated between the transfer conveyance belt 9a and the sheet, thereby electrostatically attracting both. It is supposed to give rise to.
[0044]
Further, in the double-sided image formation described later, the sheet conveying device 9 reverses the sheet on which the image is formed on the front surface by the image forming unit 52, and then again forms the sheet so as to form an image on the back surface of the sheet. The double-sided conveyance path 15 which is a re-feed conveyance path extending in the vertical direction for conveying the inverted sheet to the image forming section 52 and the double-sided conveyance path 15 are directed downward. And a positioning portion for positioning in the width direction of the sheet passing therethrough.
[0045]
Reference numeral 14 denotes a conveyance auxiliary roller as a plurality of auxiliary members arranged so as to be driven and rotated by the surface side of the transfer conveyance belt 9a. When the conveyance auxiliary roller 14 conveys the sheet by the transfer conveyance belt 9a, The sheet is prevented from peeling off from the transfer conveyance belt 9a.
[0046]
The conveyance auxiliary roller 14 is on the side carrying the sheet on the transfer conveyance belt 9a, and is configured to be integrally movable in the left-right direction by a cam mechanism (not shown). With this configuration, it also functions as a moving unit that moves the transfer conveyance belt 9a to the second position.
[0047]
Specifically, when performing multi-color recording, the conveyance auxiliary roller 14 is retracted to the left and separated from the transfer conveyance belt 9a. In this state, the transfer conveyance belt 9a is in contact with the four photosensitive drums 1a to 1d, and an image forming unit is provided while the sheet fed from the sheet feeding unit 8 is adsorbed and conveyed by the transfer conveyance belt 9a. Thus, each color toner image is sequentially transferred to form a multicolor image.
[0048]
On the other hand, when monochrome recording is performed, the cam mechanism operates, whereby the conveyance auxiliary roller 14 moves to the right, contacts the transfer conveyance belt 9a, and pushes it in. As a result, the transfer conveyance belt 9a remains in contact with the black photosensitive drum 1d but is separated from the other photosensitive drums 1a to 1c. As a result, monochrome recording can be performed.
[0049]
The fixing unit 10 applies heat and pressure to the image formed on the sheet to fix the toner image, and includes a fixing belt 10a and an elastic pressure roller 10b. Here, the fixing belt 10a is a cylindrical belt having an electromagnetic induction heat generating layer, and is guided by a belt guide member 10c having a built-in magnetic field generating means including an exciting coil and a T-shaped magnetic core.
[0050]
The elastic pressure roller 10b sandwiches the fixing belt 10a and forms a fixing nip portion N having a predetermined width with a predetermined pressure contact force with the belt guide member 10c. Then, the elastic pressure roller 10b is driven to rotate by a driving means (not shown), and the cylindrical fixing belt 10a is rotated accordingly, and electromagnetic induction heat generation of the fixing belt 10a is performed by feeding power from an excitation circuit (not shown) to the excitation coil. It has become so.
[0051]
Next, an image forming operation of the color laser printer 50 configured as described above will be described.
[0052]
First, when the surfaces of the photosensitive drums 1a to 1d uniformly charged by the chargers 2a to 2d are scanned with laser light corresponding to the image information emitted from the exposure devices 3a to 3d, the surfaces of the photosensitive drums are exposed. A latent image is formed, and the latent images are further developed by the developing devices 4a to 4d, whereby toner images of four colors of yellow, magenta, cyan, and black are formed on the surface of the photosensitive drum.
[0053]
In parallel with this toner image forming operation, the sheet accommodated in the paper feed cassette 8a is picked up by the pickup roller 8a1, or the sheet accommodated in the multi-feed tray 8b is integrated by the multi-pickup roller 8c1. After being separated and fed one by one, after being guided to the registration roller pair 8d, the registration roller pair 8d is attracted to the transfer conveyance belt 9a in synchronism with the image forming operation, and is transferred to the photosensitive drums 1a to 1d. The belt 9a is conveyed to the transfer portion T where it is in pressure contact.
[0054]
Next, on the sheet conveyed to the transfer unit T in this manner, the transfer members 5a to 5d that are arranged in the respective transfer units T and to which a voltage having a polarity opposite to that of the toner is applied act on the photosensitive drums 1a to 1d. The toner images of the respective colors are sequentially transferred on the sheet. The sheet on which the four color toner images are transferred in this way is separated from the transfer conveyance belt 9a and conveyed to the fixing device 10.
[0055]
Next, the sheet on which the unfixed toner image conveyed from the image forming unit 52 is formed is elastic with the fixing belt 10a of the fixing nip N in a state where the temperature of the fixing nip N rises to a predetermined temperature. It is introduced between the pressure roller 10b and the image surface facing upward, that is, facing the fixing belt surface. Thereafter, the image surface is brought into close contact with the outer surface of the fixing belt 10a at the fixing nip portion N and together with the fixing belt 10a. The fixing nip portion N is nipped and conveyed.
[0056]
In the process of being conveyed along the fixing nip N together with the fixing belt 10a in this way, the sheet is heated by electromagnetic induction heat generated by the fixing belt 10a, and the unfixed toner image on the sheet is heated and fixed. As a result, a full-color print image is fixed on the sheet as a permanent image. Next, after the full-color print image is fixed as a permanent image in this way, the sheet is discharged and stacked on the discharge unit 13 by the discharge roller pairs 11 and 12.
[0057]
When forming a double-sided image, as described above, the sheet having the toner image transferred on the surface is fixed by the fixing unit 10 and is discharged to the sheet discharge unit 13 while the sheet discharge sensor 18 is in the middle of being discharged. Detects the passage of the rear end. Then, based on the sheet trailing edge detection timing of the sheet discharge sensor 18, a control unit (not shown) stops the rotation of the discharge rollers 11 and 12 after a predetermined time when the trailing edge of the sheet S reaches the branching portion P.
[0058]
When the discharge rollers 11 and 12 stop in this way, the trailing edge of the sheet branches to the double-sided conveyance path 15 due to the stiffness, and then the sheet S is rotated by reversely rotating the discharge rollers 11 and 12. Is conveyed to a positioning portion 19 that regulates the position in the width direction.
[0059]
Then, after the sheet conveyed to the positioning unit 19 is corrected for skew (inclination) and lateral displacement, it is conveyed vertically downward to the U-turn roller 17, and the U-turn roller 17 and the resist It is again conveyed to the image forming unit 52 by the roller pair 8d. Note that the re-fed sheet has a toner image transferred to the non-image forming surface and the image is recorded on the non-image-formed surface in the same manner as the front surface, and is then fixed by the fixing unit 10 and is discharged to the paper discharge unit 13 by the discharge rollers 11 and 12. The paper is ejected and printing on both sides of the front and back sides is completed.
[0060]
By the way, as shown in FIG. 2, the positioning unit 19 abuts the conveyance guide 15A, which is a guide member constituting the double-sided conveyance path 15, and the sheet S conveyed on the conveyance guide 15A at a predetermined position in the lateral direction. It is comprised by the positioning means 16A which corrects so that it may convey along a direction.
[0061]
Here, the conveyance guide 15A is provided integrally with a frame member constituting the sheet conveyance device 9 and is arranged on the outer peripheral side of the transfer conveyance belt 9a. As shown in FIG. Are provided between the registration roller pair 8d and the discharge roller pairs 11 and 12, which are the start side and the end side.
[0062]
Further, by providing the conveyance guide 15A integrally with the frame of the sheet conveyance device 9 in this way, the positioning unit 16A and the transfer conveyance belt 9a can be aligned with high accuracy. The sheet whose misalignment is corrected is electrostatically attracted and held again by the transfer conveyance belt 9a in a state where the sheet is aligned at the normal lateral position by the registration roller pair 8d, and is conveyed to the transfer portion of each color.
[0063]
The positioning unit 16A is a reference member that performs positioning in a direction orthogonal to the sheet conveyance direction by abutting with a skew feeding roller 16a that is a skew feeding unit and one side edge of the sheet that has been obliquely fed by the skew feeding roller 16a. The horizontal registration guide 16b, the horizontal registration reference member 16c, and a conveyance guide (not shown). In the present embodiment, the lateral registration guide 16b and the lateral registration reference member 16c are positioned, fixed, or integrally formed with a conveyance guide 15A that is integral with the sheet conveyance device 9.
[0064]
Further, a skew roller 16d indicated by a broken line in FIG. 3 is arranged on the side opposite to the skew feeding roller 16a. Further, a side end opposite to the one end that contacts the lateral registration guide 16b of the sheet is pressed at substantially the same height position of the skew feeding roller 16a, and the sheet S is minute so as not to hinder the positioning of the sheet S. A regulating member 16e that is pressed against the conveyance guide 15A by force and is rotated by the sheet S is disposed.
[0065]
When such a regulating member 16e is provided, the sheet S conveyed from the fixing unit 10 first comes into contact with the regulating member 16e as shown in the figure, but the sheet S is brought into contact with the regulating member 16e. The brake is applied to the side (left side), whereby the sheet S rotates clockwise as indicated by S1 shown in the second line from the top in the figure, and as a result, the sheet S is lowered to the right.
[0066]
Next, the sheet S in the state of being lowered to the right as described above is obliquely fed in the direction of the lateral registration reference member 16c by the skew roller 16d and the oblique feeding roller 16a. Here, since the sheet in the state of being lowered to the right is skewed while being rotated counterclockwise by the skew feeding roller 16a and the skew roller 16d, the second sheet from the top in FIG. And like S1 and S2 shown to the 3rd, the one side end (one end) is conveyed abutting against the two horizontal resist reference members 16c. The series of operations corrects the skew (inclination) and lateral displacement of the sheet S, and the sheet S is fed again to the registration roller.
[0067]
Here, a regulating member 16e that presses the end of the sheet S opposite to the abutting end of the sheet S with the lateral registration reference member 16c is provided, and the regulating member 16e is used for the oblique feeding by the oblique feeding roller 16a. By restricting the inclination of the sheet S toward the lateral resist reference member, it is possible to prevent the sheet S from buckling during re-feeding and to prevent the sheet S from being displaced or skewed. Can do. As a result, a good double-sided image can be formed.
[0068]
Note that the position where the regulating member 16e is disposed is a position in contact with the leading edge of the sheet S in the vicinity of the position where the trailing edge of the sheet S comes off from the discharge rollers 11 and 12 in order to prevent inclination due to the weight of the sheet S. The effect is high, and the effect at the position farthest in the lateral direction from the side where the skew feeding roller 16a and the sheet S are in contact is high.
[0069]
For this reason, in the present embodiment, the configuration is such that the leading edge of the sheet S is in contact with the oblique feeding roller 16a immediately before the trailing edge of the shortest sheet S in the longitudinal direction of the sheet S passing through both sides passes through the discharge rollers 11 and 12. Yes. In the experiment for determining the position of the regulating member 16e, when the position of the regulating member 16e is ± 30 mm (vertical direction) with respect to the position just beside the oblique feeding roller 16a (upstream side), the sheet S of the oblique feeding roller 16a The result with the highest feeding ability was obtained.
[0070]
In this embodiment, as shown in FIG. 4, the regulating member 16e is moved in the direction of the arrow by a long hole 16g extending obliquely downward formed in, for example, a paper passing rib 16f provided in a frame (not shown). Held possible.
[0071]
Thereby, even if the positional relationship between the paper passing rib 16f and the double-sided paper passing surface (conveying guide 15A) is slightly deviated, the restricting member 16e moves reliably along the elongated hole 16g in the thickness direction of the sheet S. The sheet S can be pressed against the double-sided sheet passing surface. Further, since the regulating member 16e is rotatably held by the long hole 16g, the regulating member 16e is driven to rotate by the sheet S. Thereby, there is no worry of scratching the sheet S. Further, since the pressing force is determined by the weight of the regulating member 16e, the sheet S can always be pressed with a stable force.
[0072]
By the way, in the description so far, the restriction member 16e is configured to be driven and rotated by the sheet, for example, a roller-shaped one, but the present invention is not limited to this, and the restriction member 16e is a plate. A shaped elastic body may be used.
[0073]
Next, a sheet conveying apparatus according to a second embodiment of the present invention using an elastic body on a plate as such a regulating member 16e will be described.
[0074]
FIG. 5 is a diagram illustrating the configuration of the positioning unit of the sheet conveying apparatus according to the present embodiment.
[0075]
In the drawing, reference numeral 16h denotes a restricting member, and the restricting member 16h is fixed to a frame (not shown) that holds the paper passing rib 16f. In the present embodiment, the material of the regulating member 16h is an elastic body such as a PET film.
[0076]
Further, by configuring the restricting member 16h as a plate-like elastic member in this way, even if the positional relationship between the sheet passing rib 16f and the double-sided sheet passing surface is slightly deviated, the restricting member 16h can reliably transfer the sheet S on both sides. It can be pressed against the sheet passing surface. Further, the pressing force is determined by the deformation amount of the restricting member 16h, and is always a stable pressing force.
[0077]
The present invention is for positioning in a direction perpendicular to the sheet conveyance direction. As described in this embodiment, the image formed sheet is formed in the vertical direction for conveying the sheet again to the image forming unit. The transport path is not limited to the re-transport path, and may be a transport path for transporting a sheet fed from a paper feed cassette or a transport path formed horizontally.
[0078]
【The invention's effect】
As described above, according to the present invention, when the sheet is obliquely fed and one side end of the sheet is brought into contact with the reference member to perform positioning in the direction orthogonal to the sheet conveyance direction, the sheet is provided in the re-conveyance path. By pressing the end on the opposite side of the sheet with the regulating member, it is possible to regulate the inclination of the sheet toward the reference member when the sheet is fed obliquely. Seat buckling, misalignment, and skew can be prevented.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of a color laser printer that is an example of an image forming apparatus including a sheet conveying device according to a first embodiment of the invention.
FIG. 2 is a perspective view illustrating a configuration of a positioning unit of the sheet conveying apparatus.
FIG. 3 is a diagram illustrating a movement of a sheet in the positioning unit.
FIG. 4 is a diagram illustrating a configuration of a regulating member provided in the positioning unit.
FIG. 5 is a diagram illustrating a configuration of a regulating member provided in a positioning unit of a sheet conveying device according to a second embodiment of the present invention.
FIG. 6 is a diagram illustrating sheet movement in a positioning unit of a conventional sheet conveying apparatus.
[Explanation of symbols]
9 Sheet transport device
15 Double-sided conveyance path
15A transport guide
16A positioning means
16a Skew feeding roller
16d Rolling roller
16c Horizontal resist reference member
16e Restriction member
16f Paper passing rib
16g long hole
16h Regulating member
19 Positioning part
50 color laser printer
52 Image forming unit
S sheet

Claims (6)

A conveyance path formed in the vertical direction to convey the sheet;
A skew feeding means that is provided in the conveyance path and obliquely feeds the sheet passing through the conveyance path;
A reference member that is provided in the conveyance path and that is positioned in a direction perpendicular to the conveyance direction of the sheet in contact with one side end of the sheet that is obliquely fed by the skew feeding unit;
What is the one side edge of the sheet so as to restrict the drooping of the side edge opposite to the one side edge of the sheet when the sheet is obliquely fed by the skew feeding means provided in the conveyance path? A regulating member that presses the opposite side end,
Equipped with a,
The regulating member is driven to rotate by a sheet passing through the conveyance path and is movably provided in the thickness direction of the sheet, and presses the sheet with a force that does not prevent the sheet from being obliquely fed by the skew feeding unit. A sheet conveying apparatus characterized by the above. A conveyance path formed in the vertical direction to convey the sheet;
A skew feeding means that is provided in the conveyance path and obliquely feeds the sheet passing through the conveyance path;
A reference member that is provided in the conveyance path and that is positioned in a direction perpendicular to the conveyance direction of the sheet in contact with one side edge of the sheet that is obliquely fed by the skew feeding unit;
What is the one side edge of the sheet so as to restrict the drooping of the side edge opposite to the one side edge of the sheet when the sheet is obliquely fed by the skew feeding means provided in the conveyance path? A regulating member for pressing the opposite side end,
With
The regulating member is formed of a plate-like elastic member that is movable in the thickness direction of the sheet and presses the sheet passing through the conveyance path to a conveyance guide that constitutes the conveyance path, and is formed by the oblique feeding unit. A sheet conveying apparatus, wherein the sheet is pressed with a force that does not prevent the oblique feeding of the sheet. 2. The conveyance path is a re-conveyance path that conveys the sheet to the image forming unit again so that an image is formed on the back surface of the sheet having an image formed on the front surface by the image forming unit. Or the sheet conveying apparatus of 2. The sheet conveying apparatus according to claim 1 or 2 , wherein the sheet fed obliquely by the skew feeding means passes through the conveyance path downward. 5. The sheet conveying apparatus according to claim 1, wherein the regulating member is disposed at the same height position in the vertical direction as the skew feeding unit. An image forming unit, an image forming apparatus characterized by comprising a sheet conveying apparatus according to any one of claims 1 to 5.

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