JP2011126685A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device capable of preferably performing correction of skew (oblique paper-feeding) of a paper. <P>SOLUTION: The image forming device includes a pair of resist rollers 80 for feeding out a material T to be transferred to an image formation part GK after a leading end part T1 of the material T to be transferred is abutted on the pair of resist rollers 80 once in the stopping state to curve the material T to be transferred; a conveying roller 90 for conveying the material T to be transferred in a conveying direction D1; a guide member 130 capable of varying length in the conveying direction D1 to first guide length L1 that a projection of a curved shape in the curved material T to be transferred is formed at an upstream side in the conveying direction D1 of the guide member 130 and second guide length L2 longer than the first guide length L1 such that it is abutted on the curved material T to be transferred so as to press a projection side of the curved shape; a guide length changing part 140 for changing the length of the guide member 130; and a guide length change control part 210 for controlling the guide length changing part 140 so as to change the length of the guide member 130 after the material T to be transferred is abutted on the guide member 130. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copier, a printer, a facsimile, or a complex machine of these.

  Conventionally, as an apparatus for printing (forming) an image on a sheet as a transfer material, an image forming apparatus such as a copier, a printer, or a complex machine of these is known. Generally, in an image forming apparatus, a pair of registration rollers is provided on the upstream side in the sheet transport direction in an image forming unit that forms an image on a sheet. The registration roller pair is a pair of rollers for correcting skew of the paper (oblique feeding) and adjusting timing with the toner image before sending the paper to the image forming unit.

In a stopped state, the registration roller pair temporarily contacts the leading end of the sheet to bend the sheet, and then rotates to send the sheet to the image forming unit.
Specifically, the sheet that is in contact with the stopped registration roller pair is sent out to the registration roller pair side by a conveyance roller disposed on the upstream side of the registration roller pair in the sheet conveyance direction. As a result, the sheet is curved in a state in which the leading end is pressed toward the registration nip formed in the registration roller pair. Here, a reaction force is generated on the sheet in contact with the registration roller pair in a direction opposite to the sheet conveyance direction. Due to the reaction force of the paper, a force is generated on the paper to press the front end portion toward the registration nip. The registration roller pair performs paper skew (oblique feeding) correction before the paper is sent to the image forming unit by pressing the front end of the paper toward the registration nip.

  In the skew (diagonal feeding) correction using the registration roller pair, if the force with which the leading edge of the paper is pressed against the registration roller pair is weak, the paper skew (oblique feeding) correction may not be suitably performed. is there. In addition, when the force with which the leading edge of the paper is pressed against the registration roller pair is strong, the paper enters the registration nip, and thus the paper skew (oblique paper feeding) correction may not be suitably performed.

  Incidentally, the force with which the leading edge of the paper is pressed against the registration roller pair is caused by the size and shape of the curve formed on the paper. Further, the size and shape of the curve formed on the paper are adjusted by the amount of paper fed by the transport roller.

  As a technique for adjusting the paper feed amount, an image forming apparatus that includes a guide member that guides the paper to the registration nip and adjusts the paper feed amount by the conveyance roller according to the thickness and rigidity (stretch strength) of the paper. Has been proposed (see, for example, Patent Document 1).

In the image forming apparatus described in Patent Document 1, the guide member abuts on the sheet so as to press down the curved convex side of the curved sheet, and guides the sheet to the registration nip.
In the image forming apparatus described in Patent Document 1, the guide member is provided with a sheet in order to ensure a space in which the curved shape is formed when the curved shape formed on the paper comes into contact with and is applied with a predetermined force. It swings so as to be expanded in the direction in which the curved shape formed becomes larger. Thereby, the image forming apparatus described in Patent Document 1 secures a space in which a curved shape is formed on the sheet.

Japanese Patent Laid-Open No. 7-172639

  However, the image forming apparatus described in Patent Document 1 swings so that the guide member is pushed and spread in a direction in which the curved shape formed on the paper increases, thereby creating a space where the curved shape is formed on the paper. It is configured to ensure. For this reason, in the image forming apparatus described in Patent Document 1, no further contrivance has been made regarding the force with which the leading edge of the sheet is pressed against the pair of registration rollers.

  The present invention suitably performs paper skew (oblique paper feeding) correction in an image forming apparatus including a registration roller pair that feeds paper to an image forming unit and a guide member that guides the paper to a registration nip of the registration roller pair. An object of the present invention is to provide an image forming apparatus that can perform the above-described process.

  The present invention relates to an image forming unit that forms an image on a sheet-like transfer material and a registration roller pair that forms a registration nip, and in a stopped state, the tip of the transfer material is once applied to the registration roller pair. After the contacted material is bent and curved, the registration roller pair that rotationally drives the transfer material to the image forming unit and the upstream of the registration roller pair in the conveyance direction of the transfer material A conveying roller capable of conveying the transferred material in the conveying direction and stopping the transferred material by holding the transferred material in contact with a pair of registration rollers while holding the transferred material; and the resist A guide member disposed between a pair of rollers and the transport roller, for guiding the material to be transferred to the registration nip, and having a length in the transport direction that is curved in the material to be transferred. The curved convex portion is pressed against the transferred material that is curved longer than the first guide length and has a first guide length formed on the upstream side in the conveying direction of the guide member. A guide member that is variable to a second guide length that abuts the guide member, a guide length changing portion that changes the length of the guide member to the first guide length and the second guide length, and the registration roller pair is stopped. An image forming apparatus comprising: a guide length change control unit configured to control the guide length change unit so as to change a length of the guide member after the transfer material comes into contact with the guide member. About.

  The guide member is configured by a plurality of plate members, and is configured to be variable in length in the transport direction by sliding at least one of the plurality of plate members in the transport direction, The guide length changing unit preferably changes the length of the guide member in the transport direction by sliding at least one of the plurality of plate members in the transport direction.

  In addition, the guide length change control unit may be configured to change the curvature of the material to be transferred based on type information including thickness information about the thickness of the material to be transferred and / or stiffness information about the rigidity of the material to be transferred. When the curved convex portion is formed on the upstream side in the conveyance direction of the guide member, the guide length changing portion is controlled to be curved so that the length of the guide member is the first guide length. In addition, after the curved convex portion of the transfer material is formed on the upstream side in the conveyance direction of the guide member, the guide length changing portion is set so that the length of the guide member is the second guide length. It is preferable to control.

  Further, the guide length change control unit is configured to determine a curved shape of the material to be transferred based on type information including thickness information about the thickness of the material to be transferred and / or stiffness information about the rigidity of the material to be transferred. When the convex side abuts on the guide member, the guide length changing unit is controlled so that the length of the guide member is the second guide length, and the curved convex side of the transfer material is the guide side. After the contact with the member, it is preferable to control the guide length changing unit so that the length of the guide member becomes the first guide length.

  According to the present invention, in an image forming apparatus including a registration roller pair that feeds paper to an image forming unit and a guide member that guides the paper to a registration nip of the registration roller pair, correction of paper skew (oblique feeding) is preferable. An image forming apparatus that can be used in the present invention can be provided.

FIG. 3 is a diagram for explaining an arrangement of each component in the copier 1 of the present embodiment. FIG. 7 is a side view showing a detailed configuration of a registration mechanism unit RK including a registration roller pair 80 in the copying machine 1 of the present embodiment, and is a view when the length of a registration guide member 130 is a first guide length L1. . FIG. 6 is a side view showing a detailed configuration of a registration mechanism unit RK including a registration roller pair 80 in the copying machine 1 of the present embodiment, and is a view when the length of a registration guide member 130 is a second guide length L2. . FIG. 6 is a perspective view showing a configuration when the length of a resist guide member 130 is a first guide length L1 and a configuration of a guide length changing unit 140. FIG. 6 is a perspective view showing a configuration when the length of a resist guide member 130 is a second guide length L2 and a configuration of a guide length changing unit 140. 10 is a flowchart illustrating an operation flow of skew correction when the length of a resist guide member is changed from a first guide length L1 to a second guide length L2. 10 is a flowchart showing an operation flow of skew correction when the length of a resist guide member is changed from a second guide length L2 to a first guide length L1.

Hereinafter, embodiments of an image forming apparatus of the present invention will be described with reference to the drawings.
With reference to FIG. 1, the overall structure of a copier 1 as an image forming apparatus in the embodiment will be described. FIG. 1 is a diagram for explaining the arrangement of each component in the copier 1 of this embodiment.

  As shown in FIG. 1, a copier 1 as an image forming apparatus is disposed on an upper side in the vertical direction Z of the copier 1 and on a lower side of the copier 1 in the vertical direction Z. An apparatus main body M that forms a toner image on a sheet T as a sheet-like transfer material based on image information read by the image reading apparatus 300.

  In the description of the copying machine 1, the rotation axis direction of various rotating bodies (rollers, belts, etc.) in the photosensitive drum 2, the fixing unit 9, etc. is referred to as “Y direction” (direction passing through FIG. 1). The Y direction is also a direction orthogonal to the transport direction D1 of the paper T as a transfer material (see FIGS. 2A to 3B). In the Y direction, the front side in FIG. 1 is also referred to as “+ (plus) side”, and the rear side in FIG. 1 is also referred to as “− (minus) side”. The direction that is horizontal and orthogonal to the Y direction is referred to as the “X direction”. The vertical direction Z of the copier 1 is orthogonal to the X direction and the Y direction. A direction perpendicular to the transport direction D1 of the paper T and perpendicular to the Y direction is referred to as a “second direction D2” (see FIGS. 2A to 3B). In the second direction D2, a registration guide member 130 side described later is also referred to as a “+ (plus) side”, and a conveyance guide member 120 side described later is also referred to as a “− (minus) side” (see FIGS. 2A to 3B).

First, the image reading apparatus 300 will be described.
As shown in FIG. 1, the image reading apparatus 300 includes a lid member 70 and a reading unit 301 that reads an image of a document G.
The lid member 70 is connected to the reading unit 301 so as to be opened and closed by a connecting unit (not shown). The lid member 70 has a function of protecting a reading surface 302A described later.

Next, the apparatus main body M will be described.
The apparatus body M includes an image forming unit GK that forms a predetermined toner image on the paper T based on predetermined image information, and a fixing unit that fixes the toner image formed on the paper T in the image forming unit GK to the paper T. 9 and a paper supply / discharge unit KH that supplies the paper T to the image forming unit GK and discharges the paper T on which the toner image is formed.

As shown in FIG. 1, the image forming unit GK includes a photosensitive drum 2, a charging unit 10, a laser scanner unit 4 as an exposure device, a developing device 16, a toner cartridge 5, a toner supply device 6, A drum cleaning device 11 and a transfer roller 8 are provided.
The paper supply / discharge unit includes a paper feed cassette 52, a registration roller pair 80, a transport path L for paper T, a paper discharge unit 50, and a manual paper feed unit 64.

  The photosensitive drum 2 is made of a cylindrical member and functions as a photosensitive member or an image carrier. The photosensitive drum 2 is disposed so as to be rotatable in the direction of an arrow about an axis extending in a direction orthogonal to the conveyance direction of the paper T in the conveyance path L. An electrostatic latent image can be formed on the surface of the photosensitive drum 2.

  The charging unit 10 is disposed to face the surface of the photosensitive drum 2. The charging unit 10 uniformly charges the surface of the photosensitive drum 2 to be negative (minus polarity) or positive (plus polarity).

  The laser scanner unit 4 functions as an exposure unit, and is disposed away from the surface of the photosensitive drum 2. The laser scanner unit 4 includes a laser light source (not shown), a polygon mirror, a polygon mirror driving motor, and the like.

  The laser scanner unit 4 scans and exposes the surface of the photosensitive drum 2 based on image information input from a CCD substrate (not shown). By scanning exposure with the laser scanner unit 4, the charge on the exposed portion of the surface of the photosensitive drum 2 is removed. As a result, an electrostatic latent image is formed on the surface of the photosensitive drum 2.

  The developing device 16 is provided corresponding to the photosensitive drum 2 and is disposed to face the surface of the photosensitive drum 2. The developing device 16 attaches a single color (usually black) toner to the electrostatic latent image formed on the photoconductive drum 2 to form a single color toner image on the surface of the photoconductive drum 2. The developing device 16 includes a developing roller 17 disposed opposite to the surface of the photosensitive drum 2, a stirring roller 18 for stirring the toner, and the like.

  The toner cartridge 5 is provided corresponding to the developing device 16 and stores toner supplied to the developing device 16.

  The toner supply device 6 is provided corresponding to the toner cartridge 5 and the developing device 16, and supplies the toner stored in the toner cartridge 5 to the developing device 16. The toner supply device 6 and the developing device 16 are connected by a toner supply path (not shown).

  The transfer roller 8 transfers the toner image developed on the surface of the photosensitive drum 2 to the paper T. A transfer bias for transferring the toner image formed on the photosensitive drum 2 to the paper T is applied to the transfer roller 8 by a transfer bias applying unit (not shown). The transfer roller 8 is configured to be rotatable while being in contact with the photosensitive drum 2.

  A sheet T conveyed on the conveyance path L is sandwiched between the photosensitive drum 2 and the transfer roller 8. The sandwiched paper T is pressed against the surface of the photosensitive drum 2. A transfer nip N is formed between the photosensitive drum 2 and the transfer roller 8. In the transfer nip N, the toner image developed on the photosensitive drum 2 is transferred onto the paper T.

  The drum cleaning device 11 is disposed to face the surface of the photosensitive drum 2. The drum cleaning device 11 removes toner and deposits remaining on the surface of the photosensitive drum 2 and conveys the removed toner and the like to a predetermined collection mechanism for collection.

  The fixing unit 9 melts and presses the toner constituting the toner image transferred to the paper T and fixes the toner on the paper T. The fixing unit 9 includes a heating rotator 9a heated by a heater and a pressure rotator 9b pressed against the heating rotator 9a. The heating rotator 9a and the pressure rotator 9b sandwich and pressurize the paper T on which the toner image has been transferred, and convey the paper T. By transporting the paper T while being sandwiched between the heating rotator 9a and the pressure rotator 9b, the toner transferred onto the paper T is melted and pressurized, and is fixed to the paper T.

Next, the paper supply / discharge unit KH will be described.
As shown in FIG. 1, the paper supply / discharge unit KH includes a cassette paper supply unit 51, a paper supply cassette 52, a manual paper supply unit 64, a transport path L of paper T, a registration roller pair 80, and paper discharge. Part 50. As will be described later, the transport path L includes the first transport path L1, the second transport path L2, the third transport path L3, the fourth transport path L4, the fifth transport path L5, and the sixth transport. This is an assembly of the path L6 and the return transport path LB.

  As shown in FIG. 1, in the lower part of the apparatus main body M, two paper feed cassettes 52 that store paper T are arranged in the left and right (X direction). The paper feed cassette 52 is configured to be drawable in the horizontal direction from the front side (the front side in FIG. 1) of the apparatus main body M. The paper feed cassette 52 includes a placement plate 60 on which the paper T is placed, and is accommodated in a state where the paper T is stacked on the placement plate 60. When an image is formed on the paper T, the paper T placed on the placement plate 60 is placed at the paper feed side end of the paper feed cassette 52 (right end in FIG. 1). 51 is sent out to the conveyance path L. The cassette paper feed unit 51 includes a forward feed roller 61 for taking out the paper T on the placement plate 60 and a paper feed roller pair 63 for feeding the paper T one by one to the first transport path L1 of the transport path L. A double feed prevention mechanism.

  A manual paper feed unit 64 is provided on the right side of the apparatus main body M (on the right side in FIG. 1) and above the paper feed cassette 52. The manual paper feed unit 64 is provided mainly for supplying the apparatus main body M with a paper T of a size and type different from the paper T set in the paper feed cassette 52. The manual paper feed unit 64 includes a manual feed tray 65 that forms a part of the front surface of the apparatus main body M in the closed state, and a paper feed roller 66. The lower end of the manual feed tray 65 is attached to the vicinity of the paper feed roller 66 so as to be rotatable (openable and closable). The paper T is placed on the open manual feed tray 65. The paper feed roller 66 feeds the paper T placed on the open manual feed tray 65 to the first transport path L1.

The conveyance path L includes a first conveyance path L1 from the cassette paper feeding unit 51 to the registration roller pair 80, a second conveyance path L2 from the registration roller pair 80 to the transfer roller 8, and a transfer roller 8 to the fixing unit 9. The third transport path L3, the fourth transport path L4 from the fixing unit 9 to the first branching section Q1, the fifth transport path L5 from the first branching section Q1 to the paper discharge section 50, and the fourth transport path L4 A return transport path LB for transporting the paper T transported from the upstream side to the downstream side from the first branching portion Q1 to the second joining portion P2, and a sixth transport for transporting the paper T reversed upside down to the paper discharge portion 50. And a road L6.
Details of the registration mechanism RK including the registration roller pair 80 will be described later.

  A first junction P1, a second junction P2, and a third junction P3 are disposed in the first transport path L1. The first merging portion P1 is a merging portion from the cassette sheet feeding portion 51 of the two sheet feeding cassettes 52 to the first transport path L1. The second junction P2 is a junction from the return conveyance path LB to the first conveyance path L1. The third merging portion P3 is a merging portion from the manual sheet feeding portion 64 to the first transport path L1.

  The return conveyance path LB includes a bent conveyance path La that conveys the sheet T branched at the first branching portion Q1 while being bent obliquely downward, and a sheet T that is turned upside down by the bending conveyance through the second branching portion Q2. After that, the horizontal receiving portion Lb received in a horizontal posture, and the paper T that is once received by the horizontal receiving portion Lb and then fed in the reverse direction are branched at the third branching portion Q3, and again are reversed upside down. And a horizontal return transport path Lc for transporting toward the second junction P2. A roller pair 28 that forcibly conveys the paper T that is turned upside down to the horizontal return conveyance path Lc or the sixth conveyance path L6 through the third branching section Q3 is provided at the delivery end of the horizontal receiving section Lb. Yes. Further, the first branch part Q1, the second branch part Q2, and the third branch part Q3 are provided with transport path switching members 30, 31, and 32, respectively.

  When the double-sided printing of the paper T is performed, the return transport path LB reverses the front and back and the front and back of the paper T after being fixed by the fixing unit 9, thereby reversing the surface that has been printed (non-printing). This is a transport path for transporting so that the surface) faces the photosensitive drum 2. Further, the sixth transport path L6 passes through the bent transport path La in the return transport path LB, and is discharged in a state where the paper T once received by the horizontal receiving portion Lb is turned upside down (in a state where the printing surface is down). This is a conveyance path for carrying out to the paper unit 50.

  A paper discharge unit 50 is provided above the left side (left side in FIG. 1) of the apparatus main body M. The paper discharge unit 50 opens toward the left side of the apparatus main body M. The paper discharge unit 50 discharges the paper T transported through the fifth transport path L5 or the paper T transported through the sixth transport path L6 onto a paper discharge tray 54 outside the apparatus main body M by the roller pair 53.

  Hereinafter, a configuration related to the registration mechanism unit RK, which is a characteristic part of the copier 1 of the present embodiment, will be described with reference to the drawings. FIG. 2A is a side view showing a detailed configuration of the registration mechanism unit RK including the registration roller pair 80 in the copier 1 of the present embodiment, and the length of the registration guide member 130 is the first guide length L1. FIG. FIG. 2B is a side view showing a detailed configuration of the registration mechanism unit RK including the registration roller pair 80 in the copying machine 1 of the present embodiment, and the length of the registration guide member 130 is the second guide length L2. FIG. FIG. 3A is a perspective view showing the configuration when the length of the resist guide member 130 is the first guide length L1 and the configuration of the guide length changing unit 140. FIG. FIG. 3B is a perspective view showing the configuration when the length of the resist guide member 130 is the second guide length L2 and the configuration of the guide length changing unit 140.

  As shown in FIGS. 2A and 2B, the registration mechanism portion RK of the present embodiment includes a registration roller pair 80, a first conveyance roller pair 90 as a conveyance roller, a conveyance guide member 120, and a registration guide as a guide member. A member 130, a pre-registration sensor S, and a guide length changing unit 140 are provided.

The registration roller pair 80 is disposed on the upstream side in the transport direction D1 of the paper T in the transfer nip N of the image forming unit GK (see FIG. 1).
The registration roller pair 80 is composed of two roller members facing each other. The two roller members in the registration roller pair 80 are configured to be rotatable around a rotation axis parallel to the Y direction. A motor (not shown) is connected to the registration roller pair 80. The registration roller pair 80 rotates or stops by driving a motor.

A registration nip RN is formed between the two roller members in the registration roller pair 80. The paper T conveyed on the first conveyance path L1 is conveyed toward the registration nip RN.
The leading end T1 of the paper T that is transported through the first transport path L1 contacts the registration roller pair 80 that is stopped. The sheet in contact with the registration roller pair 80 is sent out in the conveyance direction D1 by a first conveyance roller pair 90 described later, and in the second direction on the upstream side of the conveyance direction D1 of the registration nip RN in the first conveyance path L1. Curved convexly on the plus side in D2.
In this way, when the registration roller pair 80 is in the stopped state, the registration roller pair 80 bends the paper T by once contacting the leading end T1 of the paper T conveyed on the first conveyance path L1. .

  After the leading end T1 of the paper T once comes into contact with the registration roller pair 80, the registration roller pair 80 is driven to rotate. Thereby, the paper T is introduced into the registration nip RN. The paper T introduced into the registration nip RN is sent out to the second conveyance path L2 by the registration roller pair 80 while being sandwiched between two roller members in the registration roller pair 80. As described above, the registration roller pair 80 sends the paper T toward the transfer nip N in the image forming unit GK.

  As shown in FIGS. 2A and 2B, the first transport roller pair 90 is disposed on the upstream side in the transport direction D1 of the paper T in the registration roller pair 80. Specifically, the first conveyance roller pair 90 is a conveyance roller pair that is positioned closest to the registration roller pair 80 among a plurality of conveyance roller pairs that convey the paper T toward the image forming unit GK.

  The first transport roller pair 90 is composed of two roller members facing each other. The two roller members in the first conveying roller pair 90 are configured to be rotatable around a rotation axis parallel to the rotation axis direction of the registration roller pair 80. A conveyance roller driving unit 910 configured by a motor or the like is connected to the first conveyance roller pair 90. The first conveyance roller pair 90 rotates or stops by driving the conveyance roller driving unit 910. As a result, the first transport roller pair 90 feeds the paper T toward the registration roller pair 80 in a state where the paper T is sandwiched between the two roller members.

The first transport roller pair 90 transports the paper T in the transport direction D1, and brings the leading end T1 of the paper T into contact with the registration roller pair 80 in a state where the paper T is sandwiched. The first transport roller pair 90 feeds the paper T in a state where the paper T is sandwiched by driving of the transport roller driving unit 910, and causes the leading end T 1 of the paper T to contact the registration roller pair 80. The first conveying roller pair 90 bends the paper T by feeding the paper T in contact with the registration roller pair 80 further to the registration roller pair 80 side. The first transport roller pair 90 sends out the paper T, whose tip T1 is in contact with the registration roller pair 80, so as to bend in a convex shape in the second direction D2.
The first conveying roller pair 90 stops rotating after the paper T is sent out for a predetermined length.

The delivery length of the paper T in the first conveying roller pair 90 is set for each apparatus according to various design conditions. In the present embodiment, the first transport roller pair 90 is based on a passage signal of the paper T output by a pre-registration sensor S (described later) disposed on the upstream side of the registration roller pair 80 in the transport direction D1 of the paper T. Then, it is driven to rotate for a predetermined time by the transport roller driving unit 910. Thereby, the paper T is sent out for a predetermined length in the transport direction D1. Further, the first transport path L1 is convexly curved toward the plus side in the second direction D2. As a result, the paper T is curved in a convex shape on the plus side in the second direction D2.
As described above, the first conveying roller pair 90 presses the leading end T1 of the paper T against the registration roller pair 80, thereby correcting the skew (oblique feeding) of the paper T before sending the paper T to the image forming unit GK. Is going.

  As shown in FIGS. 2A and 2B, the conveyance guide member 120 and the registration guide member 130 are arranged so that the distance between them becomes narrower as it approaches the position immediately before the registration roller pair 80 in the first conveyance path L1. As a result, the paper T sent out from the first conveyance roller pair 90 is guided by the conveyance guide member 120 and the registration guide member 130 and conveyed toward the registration nip RN.

The conveyance guide member 120 is a planar plate member. The conveyance guide member 120 is disposed on one surface side (minus side in the second direction D2) of the sheet T to be conveyed between the first conveyance roller pair 90 and the registration roller pair 80.
The conveyance guide member 120 is directed toward the registration roller pair 80 while guiding the sheet T fed from the first conveyance roller pair 90 on one surface side (the surface opposite to the printing surface) of the sheet T being conveyed. Transport.

The registration guide member 130 is arranged between the registration roller pair 80 and the first conveyance roller pair 90 and is arranged on the other surface side (printing surface side) of the conveyed paper T. The registration guide member 130 is positioned in the vicinity of the registration nip RN at the downstream end in the transport direction D1, and approaches the transport guide member 120 toward the downstream end in the transport direction D1 (second direction D2). (Minus side).
The registration guide member 130 guides the paper T curved in a convex shape to the registration nip RN when the leading end T1 of the paper T abuts the registration roller pair 80.

  As shown in FIGS. 2A to 3B, the resist guide member 130 includes a planar first plate member 130a and a planar second plate member 130b. The first plate member 130a and the second plate member 130b are members that are long in the Y direction. When viewed from the second direction D2, the resist guide member 130 is configured such that a part or all of the first plate member 130a and the second plate member 130b overlap each other. Specifically, the first plate member 130a and the second plate member 130b are arranged so as to overlap in the second direction D2. The first plate member 130a is disposed on the plus side in the second direction D2 with respect to the second plate member 130b.

  The first plate member 130a and the second plate member 130b are arranged at the same angle with respect to the Y-D1 plane (horizontal plane in FIGS. 2A and 2B). Specifically, the first plate member 130a and the second plate member 130b are arranged in an inclined posture having an inclination of, for example, 20 ° to 25 ° with respect to the Y-D1 plane (horizontal plane in FIGS. 2A and 2B). ing.

  The first plate member 130a is disposed on the registration roller pair 80 side in the transport direction D1, and is fixed to the apparatus main body M or the like. The second plate member 130b is arranged on the first conveyance roller pair 90 side in the conveyance direction D1, and is configured to be slidable in the conveyance direction D1 along the first plate member 130a.

  As shown in FIGS. 3A and 3B, first through-holes 133 and 133 having a predetermined length are formed in the vicinity of both ends in the Y direction of the first plate member 130a. The first through holes 133 and 133 are formed so as to be inclined inward from the end side of the first plate member 130a toward the downstream side from the upstream side in the transport direction D1.

  In the vicinity of both ends in the Y direction of the second plate member 130b, second through holes 134, 134 having a predetermined length are formed. The second through holes 134 and 134 are formed along the Y direction so as to go inward from the end side of the second plate member 130b.

  The first plate member 130 a and the second plate member 130 b are connected by two pin members 135 and 135. The pin member 135 is configured to be movable along the first through long hole 133 and the second through long hole 134 while passing through the first through long hole 133 and the second through long hole 134.

  The pin member 135 moves along the first through long hole 133 and the second through long hole 134 when the second plate member 130b is moved along the first plate member 130a. When the pin member 135 moves along the first through long hole 133 and the second through long hole 134, the second plate member 130b is moved along the first plate member 130a.

  By being configured in this way, the resist guide member 130 is configured such that the length in the transport direction D1 is variably set to the first guide length L1 and the second guide length L2. The second guide length L2 is longer than the first guide length L1. The first guide length L1 is, for example, 10 mm to 20 mm. The second guide length L2 is, for example, 25 mm to 35 mm.

  When the registration guide member 130 has the first guide length L1, the curved convex portion of the curved paper T is formed on the upstream side in the conveyance direction D1 of the registration guide member 130. When the registration guide member 130 has the second guide length L2, the registration guide member 130 contacts the curved sheet T so as to press the convex side of the curved shape.

  The pre-registration sensor S is disposed along the first conveyance path L1 between the registration roller pair 80 and the first conveyance roller pair 90. The pre-registration sensor S detects that the paper T has passed and outputs a detection signal to the control unit 200.

3A and 3B, the guide length changing unit 140 includes a pair of projecting members 143 and 143, a pair of rails 141 and 141, a pair of sliding movement members 142 and 142, and a guide length changing drive. Part 149.
The pair of projecting members 143 and 143 are connected to the upstream end of the second plate member 130b in the transport direction D1. The pair of projecting members 143 and 143 are formed to project outward from both end portions in the Y direction of the second plate member 130b on the upstream end side in the transport direction D1 of the second plate member 130b. .

  The pair of rails 141 and 141 are located on the minus side in the second direction D2 on the plus side end side and the minus side end side in the Y direction of the registration guide member 130 along the transport direction D1 of the paper T. Arranged in parallel.

  The pair of sliding movement members 142 and 142 are on the plus side in the second direction D2 with respect to the pair of rails 141 and 141 on the plus side end side and the minus side end side of the registration guide member 130 in the Y direction. Be placed. The pair of sliding movement members 142, 142 are formed to extend in the second direction D2. The pair of sliding movement members 142 and 142 are configured to be engaged with the pair of rails 141 and 141 so as to be movable along the transport direction D1.

  The sliding member 142 has a long hole 142a penetrating from the plus side to the minus side in the Y direction. The long hole 142a is formed long so as to extend in the second direction D2. The protruding member 143 is inserted through the long hole 142a. The protruding member 143 moves along the transport direction D1 and moves along the long hole 142a in the second direction D2 when the sliding member 142 moves along the transport direction D1.

  The sliding movement member 142 is configured to be movable along the conveyance direction D1 by the guide length change driving unit 149. More specifically, the output shaft 149a of the guide length changing drive unit 149 is connected to the side surface of one sliding member 142 arranged on the plus side in the Y direction. The output shaft 149a of the guide length change drive unit 149 reciprocates linearly along the transport direction D1. Thereby, the sliding movement member 142 moves along the conveyance direction D1. The guide length change drive unit 149 is configured by, for example, a solenoid.

The guide length changing unit 140 moves the output shaft 149a of the guide length change driving unit 149 along the conveying direction D1, thereby moving the second plate member 130b in the conveying direction via the sliding member 142 and the protruding member 143. Move along D1.
Thereby, the guide length changing unit 140 changes the length of the registration guide member 130 in the transport direction D1. Specifically, the guide length changing unit 140 changes the length of the resist guide member 130 to be in the range of 10 mm to 30 mm, for example.

Next, a configuration related to the control of the copy machine 1 will be described.
As shown in FIGS. 2A to 3B, the copier 1 includes a control unit 200 and a storage unit 250. The control unit 200 includes a guide length change control unit 210 and a conveyance roller drive control unit 220.
The guide length change control unit 210 changes the length of the resist guide member 130 based on the type information of the paper T including the thickness information about the thickness of the paper T and the rigidity information about the rigidity of the paper T. The guide length changing unit 140 is controlled.

  The guide length change control unit 210 includes paper T type information including thickness information related to the thickness of the paper T selected by a paper type selection button (not shown) of the copier 1 and rigidity information related to the rigidity of the paper T. The movement amount (length change amount) of the guide length changing unit 140 is determined with reference to information stored in the storage unit 250 to be described later, and the determined operation amount is used as the guide length changing unit. Output to 140.

  The guide length change control unit 210 controls the guide length change unit 140 to change the length of the registration guide member 130 after the sheet T abuts the registration guide member 130 when the registration roller pair 80 is stopped. Control.

  For example, the guide length change control unit 210 determines the length of the resist guide member 130 when the curved convex portion of the curved paper T is formed on the upstream side in the transport direction D1 of the resist guide member 130. The guide length changing unit 140 is controlled so as to have one guide length L1 (see FIG. 2A), and the curved convex portion of the curved sheet T is formed on the upstream side in the transport direction D1 of the registration guide member 130. Thereafter, the guide length changing unit 140 is controlled so that the length of the resist guide member 130 is the second guide length L2 (see FIG. 2B).

  Further, when the convex side of the curved shape of the paper T comes into contact with the registration guide member 130, the guide length change control unit 210 sets the length of the registration guide member 130 to the second guide length L2 (see FIG. 2B). After the guide length changing unit 140 is controlled so that the convex side of the curved shape of the paper T comes into contact with the registration guide member 130, the length of the registration guide member 130 is set to the first guide length L1 (see FIG. 2A). ) To control the guide length changing unit 140.

  The transport roller drive control unit 220 is configured to stop the rotation of the first transport roller pair 90 after a predetermined time based on the information of the detection signal of the paper T detected by the pre-registration sensor S. To control. As a result, the first transport roller pair 90 sends out the paper T having the leading end T1 in contact with the registration roller pair 80 to the registration roller pair 80 side by a predetermined length. As a result, the sheet T is curved in a state where the leading end T1 is in contact with the registration roller pair 80.

The storage unit 250 stores information regarding the operation amount of the guide length changing unit 140 corresponding to the paper type.
In the present embodiment, the storage unit 250 stores information regarding the operation amount of the first guide length L1 and information regarding the operation amount of the second guide length L2. For example, the first guide length L1 is the length of the resist guide member 130 that is shorter than the second guide length L2. In other words, the second guide length L2 is the length of the resist guide member 130 that is longer than the first guide length L1.
Information stored in the storage unit 250 is referred to by the guide length change control unit 210.

Incidentally, the paper T having various thicknesses is used in the copying machine 1. When the thickness of the paper T is different, the rigidity (strength of the waist) is different corresponding to the thickness of the paper T. Further, even for the paper T having the same thickness, various types (stiffness) of paper T are selectively used such that the rigidity (strength) differs depending on the material. .
Then, depending on the type (rigidity) of the paper T to be used, a difference occurs in the force (hereinafter, also referred to as “front end pressing force”) by which the front end T1 of the paper T is pressed against the registration roller pair 80. This difference is one of the factors that prevent skew correction from being performed properly.

  The registration mechanism unit RK in the present embodiment has a function of adjusting the tip pressing force that varies depending on the type (rigidity) of the paper T to be used. Specifically, the registration mechanism unit RK adjusts the tip pressing force by changing the size of the curved shape formed on the paper T using the registration guide member 130.

  In the present embodiment, the length of the resist guide member 130 in the transport direction D1 is changed by sliding the second plate member 130b of the resist guide member 130 upstream in the transport direction D1.

  When the sheet T is the same type, or when the registration guide member 130 is short (for example, the first guide length L1, see FIG. 2A) Since the resist guide member 130 does not restrict the formation of the curve in the plus direction in the second direction D2 on the upstream side in the transport direction D1 of the resist guide member 130, the curved convexity of the curved sheet T is It may be formed on the upstream side in the transport direction D1.

  Specifically, as shown in FIG. 2A, when the length of the resist guide member 130 is the first guide length L1, the curved sheet T is a portion on the downstream side in the transport direction D1 with respect to the curved convex. Is in contact with the upstream end of the registration guide member 130 in the transport direction D1. Further, the convex shape of the curved shape of the paper T is in a state where the formation of the registration guide member 130 on the plus side in the second direction D2 is not sufficiently restricted by the registration guide member 130 on the upstream side in the transport direction D1. Therefore, the curved convex formed on the paper T is formed so as to protrude to the plus side in the second direction D2 from the resist guide member 130.

  On the other hand, the amount of deflection of the paper T when contacting the resist guide member 130 is the same when the paper T is the same type, or when the resist guide member 130 is long (see, for example, the second guide length L2, see FIG. 2B). May contact the curved paper T so as to press the convex side of the curved shape.

  Specifically, as shown in FIG. 2B, when the length of the registration guide member 130 is the second guide length L2, the curved sheet T has a curved convex portion in the conveyance direction in the registration guide member 130. It is in contact with the upstream end of D1. Further, the convex shape of the curved shape of the paper T is in a state where the registration guide member 130 restricts the formation of the registration guide member 130 on the plus side in the second direction D2 on the upstream side in the transport direction D1. Therefore, the curved convex formed on the paper T is formed so as not to protrude to the plus side in the second direction D2 from the resist guide member 130.

  Therefore, when the length of the resist guide member 130 is the first guide length L1, the convex shape of the curved shape of the paper T is large, and when the length of the resist guide member 130 is the second guide length L2, the paper is The convexity of the curved shape of T becomes small.

  The paper T abutted on the registration guide member 130 in the case of the first guide length L1 (the paper T on which the curved convex portion is formed largely) is abutted against the registration guide member 130 in the case of the second guide length L2. The leading edge pressing force of the paper T is smaller than that of the paper T to be contacted (paper T having a curved convex shape formed small). In other words, the paper T abutted on the registration guide member 130 in the case of the second guide length L2 (the paper T on which the convex curve is formed small) is the registration guide member in the case of the first guide length L1. The leading edge pressing force of the paper T is larger than that of the paper T abutted on the paper 130 (the paper T on which the convex curve is formed larger).

  Further, the guide length changing unit 140 changes the size of the curved shape formed on the paper T, so that the leading edge pressing force when the leading edge T1 of the paper T abuts against the registration roller pair 80 is changed to the paper T. Adjust so that it is within the set range without being affected by the type. Specifically, the guide length changing unit 140 changes the length of the registration guide member 130 in the transport direction D1 corresponding to the type (rigidity) of the paper T to be used.

  Further, the guide length change control unit 210 refers to the information stored in the storage unit 250 based on the type information of the paper T to be used, and determines the position change amount of the guide length change unit 140. Then, the guide length change control unit 210 controls the guide length change unit 140.

  Specifically, for example, the guide length change control unit 210 determines that the registration guide member 130 is formed when the curved convex shape of the curved paper T is formed on the upstream side in the conveyance direction D1 of the registration guide member 130. The guide length changing unit 140 is controlled so that the length of the first guide length L1 (see FIG. 2A). Further, the guide length change control unit 210 sets the length of the resist guide member 130 to the second length after the curved convex portion of the curved paper T is formed on the upstream side in the transport direction D1 of the resist guide member 130. The guide length changing unit 140 is controlled so as to have the guide length L2 (see FIG. 2B).

  Therefore, the leading edge pressing force of the sheet T is the leading edge pressing force at the second guide length L2 from the leading edge pressing force at the first guide length L1 in a state where the leading end T1 of the sheet T is pressed toward the registration nip RN. Will be increased. As a result, after the skew correction of the paper T is performed with the leading edge pressing force at the first guide length L1, the skew correction of the paper T can be appropriately performed with the leading edge pressing force at the second guide length L2.

  Further, when the convex side of the curved shape of the paper T comes into contact with the registration guide member 130, the guide length change control unit 210 sets the length of the registration guide member 130 to the second guide length L2 (see FIG. 2B). Thus, the guide length changing unit 140 is controlled. Further, after the convex side of the curved shape of the paper T comes into contact with the registration guide member 130, the guide length change control unit 210 sets the length of the registration guide member 130 to the first guide length L1 (see FIG. 2A). Thus, the guide length changing unit 140 is controlled.

  Therefore, the leading edge pressing force of the sheet T is the leading edge pressing force at the first guide length L1 from the leading edge pressing force at the second guide length L2 in a state where the leading end T1 of the sheet T is pressed toward the registration nip RN. Reduced to Thus, after the skew correction of the paper T is performed with the leading edge pressing force at the second guide length L2, the skew correction of the paper T can be appropriately performed with the leading edge pressing force at the first guide length L1.

Next, with reference to FIG. 1, the operation of the copier 1 of the present embodiment will be briefly described.
First, a case where single-sided printing is performed on the paper T stored in the paper feed cassette 52 will be described.
The paper T accommodated in the paper feed cassette 52 is sent out to the first transport path L1 by the forward feed roller 61 and the paper feed roller pair 63, and then the registration rollers via the first junction P1 and the first transport path L1. Transported to pair 80.
In the registration roller pair 80, skew correction of the paper T and timing adjustment with the toner image are performed. The skew correction operation by the registration mechanism RK including the registration roller pair 80 will be described later.

The paper T discharged from the registration roller pair 80 is introduced into the transfer nip N between the photosensitive drum 2 and the transfer roller 8 via the first conveyance path L1. In the transfer nip N, the toner image developed on the photosensitive drum 2 is transferred onto the paper T.
Thereafter, the sheet T is discharged from the transfer nip N between the photosensitive drum 2 and the transfer roller 8 to the second conveyance path L2, and is added to the heating rotator 9a in the fixing unit 9 via the second conveyance path L2. It is introduced into the fixing nip with the pressure rotating body 9b. Then, in the fixing nip, the toner TN is melted and pressed, and the toner TN is fixed on the paper T.

Next, the paper T is transported to the paper discharge unit 50 through the third transport path L3, and is discharged from the paper discharge unit 50 onto the paper discharge tray 54 outside the apparatus main body M by the roller pair 53.
In this way, single-sided printing of the paper T stored in the paper feed cassette 52 is completed.

  When single-sided printing is performed on the paper T placed on the manual feed tray 65, the paper T placed on the manual feed tray 65 is sent out to the manual feed path L by the paper feed roller 66, and then the third joining portion. It is transported to the first transport path L1 via P3, and transported to the registration roller pair 80 via the first transport path L1. Subsequent operations are the same as the one-side printing operation of the paper T accommodated in the paper feed cassette 52 described above, and a description thereof will be omitted.

Next, the operation of the copier 1 when performing duplex printing will be described.
In the case of single-sided printing, as described above, the paper T on which single-sided printing has been performed is discharged from the paper discharge unit 50 to the outside of the apparatus main body M, and the printing operation is completed.
On the other hand, when performing double-sided printing, the paper T on which single-sided printing has been performed is reversed from the time of single-sided printing and conveyed again to the registration roller pair 80 via the return conveyance path LB. Then, printing is performed on the surface (non-printing surface) opposite to the surface on which the paper T has already been printed, and the double-sided printing is completed.

  Next, a first example of a specific operation of skew correction by the registration mechanism unit RK, which is a characteristic part of the copier 1 of the present embodiment, will be described with reference to FIGS. 2A to 4. FIG. 4 is a flowchart showing an operation flow of skew correction when the length of the resist guide member 130 is changed from the first guide length L1 to the second guide length L2.

  The first embodiment is a specific example of skew correction performed mainly when using a paper T having low rigidity (low stiffness). Specifically, in the first embodiment, the skew correction of the paper T is performed by the registration guide member 130 at the first guide length L1, and then the skew correction of the paper T is performed by the registration guide member 130 at the second guide length L2. I do.

In step ST11, the type of paper T to be used for printing is selected by a paper type selection button (not shown) of the copier 1.
In step ST <b> 12, the guide length change control unit 210 refers to the storage unit 250 based on the type (rigidity) information of the selected paper T, and the operation amount (length change) of the guide length change unit 140. Amount). The guide length change control unit 210 outputs information related to the operation amount of the guide length change unit 140 to the guide length change unit 140.

  In step ST13, as shown in FIG. 2A, the guide length change control unit 210 controls the guide length change unit 140 so that the length of the registration guide member 130 becomes the first guide length L1.

  Based on the information on the operation amount related to the first guide length L1 determined and output by the guide length change control unit 210, the guide length change driving unit 149 drives the sliding movement member 142 in the guide length changing unit 140. I do. Therefore, the second plate member 130b in the resist guide member 130 moves along the transport direction D1. As a result, the length of the resist guide member 130 is changed (maintained) to the first guide length L1.

In step ST <b> 14, the paper T is sent out along the transport direction D <b> 1 of the paper T by the first transport roller pair 90.
The paper T sent to the first conveyance roller pair 90 is detected by a pre-registration sensor S disposed along the first conveyance path L1 between the registration roller pair 80 and the first conveyance roller pair 90. The pre-registration sensor S outputs information on the detection signal of the paper T to the transport roller drive control unit 220. Thereafter, the paper T sent out to the first conveyance roller pair 90 is conveyed from the upstream end side in the conveyance direction D1 of the registration guide member 130 toward the registration roller pair 80.

  In step ST15, the paper T comes into contact with the registration roller pair 80 in which the leading end T1 of the paper T is stopped. Then, a portion (curved portion) Ta following the leading end T1 of the paper T is curved in a convex shape on the plus side in the second direction D2 (see FIG. 2A).

  The curved sheet T has a curved convex portion formed on the upstream side in the conveyance direction D1 of the registration guide member 130, and the registration guide member 130 on the downstream side in the conveyance direction D1 from the apex of the curved convex shape. Abut. The skew correction of the paper T is performed with the leading edge pressing force at the first guide length L1 (the leading edge pressing force smaller than the second guide length L2 described later). The curved sheet T is guided toward the registration nip RN in a state where the downstream side in the transport direction D1 is pressed by the registration guide member 130 from the apex of the curved convex.

  In step ST16, based on the information output from the pre-registration sensor S, the transport roller drive control unit 220 causes the transport roller drive unit 910 to stop the rotation of the first transport roller pair 90 after a predetermined time.

  Here, since the length of the registration guide member 130 is the first guide length L1, the curved sheet T has a portion on the downstream side in the conveyance direction D1 from the convex of the curved shape in the conveyance direction in the registration guide member 130. It is in contact with the upstream end of D1. Further, the convex shape of the curved shape of the paper T is in a state where the formation of the registration guide member 130 on the plus side in the second direction D2 is not sufficiently restricted by the registration guide member 130 on the upstream side in the transport direction D1. Therefore, the curved convex portion of the paper T is formed so as to protrude to the plus side in the second direction D2 from the registration guide member 130 on the upstream side in the transport direction D1 of the registration guide member 130.

  In step ST17, as shown in FIG. 2B, the guide length change control unit 210 controls the guide length change unit 140 to change the guide length from the first guide length L1 to the second guide length L2. To do. The second guide length L2 is the length of the resist guide member 130 that is longer than the first guide length L1.

  By changing the length of the resist guide member 130 from the first guide length L1 to the second guide length L2, the convex shape of the curved shape of the paper T is formed on the plus side in the second direction D2. This is a state regulated by the member 130. Therefore, the curved paper T abuts against the resist guide member 130 so that the convex side of the curved shape is pressed.

  As a result, the curved convex formed on the paper T abutting on the registration guide member 130 at the second guide length L2 is formed on the paper T abutting on the registration guide member 130 at the first guide length L1. It becomes smaller than the convex of the curved shape to be formed.

  Thereby, the leading edge pressing force of the sheet T is smaller than the leading edge pressing force (the second guide length L2) at the first guide length L1 in a state where the leading end T1 of the sheet T is pressed toward the registration nip RN. It is increased from the tip pressing force) to the tip pressing force at the second guide length L2 (tip pressing force larger than the first guide length L1).

  Therefore, after the skew correction of the paper T is performed with the front end pressing force at the first guide length L1 (the front end pressing force smaller than the second guide length L2), the front end pressing force at the second guide length L2 (first The skew correction of the paper T can be properly performed with the leading edge pressing force larger than the guide length L1.

  Thus, by suitably adjusting the tip pressing force, it is possible to prevent the tip pressing force from being insufficient and the skew (oblique feeding) correction from being performed accurately. Therefore, it is difficult to be affected by the type (rigidity) of the paper T, and appropriate skew correction is performed.

  In step ST18, after skew correction of the paper T performed by the leading edge pressing force at the first guide length L1 and the second guide length L2, the registration roller pair 80 is driven to rotate. The paper T is sent out toward the transfer nip N of the image forming unit GK. The skew-corrected sheet T is guided to the registration nip RN with an appropriate leading edge pressing force.

Next, a second embodiment in a specific operation of skew correction by the registration mechanism unit RK will be described with reference to FIGS. 2A to 3B and FIG. FIG. 5 is a flowchart showing a skew correction operation flow when the length of the resist guide member 130 is changed from the second guide length L2 to the first guide length L1.
The second embodiment is a specific example of skew correction performed mainly when a sheet T having a large rigidity (strong stiffness) is used. Specifically, in the second embodiment, the skew correction of the paper T is performed by the registration guide member 130 at the second guide length L2, and then the skew correction of the paper T is performed by the registration guide member 130 at the first guide length L1. This is different from the first embodiment in that

  Since the operations in step ST21 and step ST22 in the second embodiment are the same as the operations in step ST11 and step ST12 in the first embodiment, the description of the operations in step ST11 and step ST12 in the first embodiment is incorporated. The description of the second embodiment is omitted.

  In step ST23, as shown in FIG. 2B, the guide length change control unit 210 controls the guide length change unit 140 so that the length of the resist guide member 130 becomes the second guide length L2.

  Based on the information on the operation amount related to the second guide length L2 determined and output by the guide length change control unit 210, the guide length change drive unit 149 drives the sliding movement member 142 in the guide length change unit 140. I do. Therefore, the second plate member 130b in the resist guide member 130 moves along the transport direction D1. As a result, the length of the resist guide member 130 is changed (maintained) to the second guide length L2.

In step ST <b> 24, the paper T is sent out along the transport direction D <b> 1 of the paper T by the first transport roller pair 90.
The paper T sent to the first conveyance roller pair 90 is detected by a pre-registration sensor S disposed along the first conveyance path L1 between the registration roller pair 80 and the first conveyance roller pair 90. The pre-registration sensor S outputs information on the detection signal of the paper T to the transport roller drive control unit 220. Thereafter, the paper T sent out to the first conveyance roller pair 90 is conveyed from the upstream end side in the conveyance direction D1 of the registration guide member 130 toward the registration roller pair 80.

  In step ST25, the paper T comes into contact with the registration roller pair 80 in which the leading end T1 of the paper T is stopped. Then, a portion (curved portion) Ta following the leading end T1 of the paper T is curved in a convex shape on the plus side in the second direction D2 (see FIG. 2B).

  The curved sheet T abuts on the resist guide member 130 having the second guide length L2 so that the convex side of the curved shape is pressed down. The skew correction of the paper T is performed by the leading edge pressing force at the second guide length L2. The curved paper T is guided toward the registration nip RN in a state where the convex side of the curved shape is pressed by the registration guide member 130.

In step ST26, based on the information output from the pre-registration sensor S, the transport roller drive control unit 220 causes the transport roller drive unit 910 to stop the rotation of the first transport roller pair 90 after a predetermined time.
Since the length of the resist guide member 130 is the second guide length L2, the convex shape of the curved shape of the paper T is in a state in which the formation on the plus side in the second direction D2 is restricted by the resist guide member 130. Therefore, the curved paper T abuts against the resist guide member 130 so that the convex side of the curved shape can be pressed.

  Here, when the paper T has high rigidity, if the leading end T1 of the paper T is pressed toward the registration nip RN for a long time, the leading end pressing force is excessive and the leading end T1 of the paper T enters the registration nip RN. May end up. For this reason, after the skew correction of the paper T is performed by the leading edge pressing force at the second guide length L2, the skew correction of the leading edge of the paper T is weakened to perform an appropriate skew correction.

  In step ST27, as shown in FIG. 2A, the guide length change control unit 210 controls the guide length change unit 140 to change the guide length from the second guide length L2 to the first guide length L1. To do. The first guide length L1 is the length of the resist guide member 130 shorter than the second guide length L2.

  When the length of the resist guide member 130 is changed from the second guide length L2 to the first guide length L1, the curved sheet T has a portion on the downstream side in the transport direction D1 with respect to the curved projection. The resist guide member 130 is in contact with the upstream end of the conveyance direction D1. Further, the convex shape of the curved shape of the paper T is in a state where the formation of the registration guide member 130 on the plus side in the second direction D2 is not sufficiently restricted by the registration guide member 130 on the upstream side in the transport direction D1. Therefore, the curved convex portion of the paper T is formed so as to protrude to the plus side in the second direction D2 from the registration guide member 130 on the upstream side in the transport direction D1 of the registration guide member 130.

  The curved convex formed on the paper T that contacts the registration guide member 130 at the first guide length L1 is formed on the paper T that contacts the registration guide member 130 at the second guide length L2. It becomes larger than the convex of the curved shape.

  Thus, the leading edge pressing force of the sheet T is larger than the leading edge pressing force (the first guide length L1) at the second guide length L2 in a state where the leading end T1 of the sheet T is pressed toward the registration nip RN. The tip pressing force is reduced from the tip pressing force at the first guide length L1 (tip pressing force smaller than the second guide length L2).

  Therefore, after the skew correction of the paper T is performed with the front end pressing force at the second guide length L2 (the front end pressing force larger than the first guide length L1), the front end T1 of the paper T enters the registration nip RN. Therefore, the skew correction of the paper T can be appropriately performed with the tip pressing force at the first guide length L1 (tip pressing force smaller than the second guide length L2).

  As described above, the leading edge pressing force is suitably adjusted, so that the leading edge pressing force is excessive and the leading edge T1 of the paper T enters the registration nip RN, so that skew (oblique feeding) cannot be accurately corrected. Is suppressed. Therefore, it is difficult to be affected by the type (rigidity) of the paper T, and appropriate skew correction is performed.

  In step ST28, after skew correction of the paper T performed by the leading edge pressing force at the second guide length L2 and the first guide length L1, the registration roller pair 80 is driven to rotate. The paper T is sent out toward the transfer nip N of the image forming unit GK. The skew-corrected sheet T is guided to the registration nip RN with an appropriate leading edge pressing force.

According to the copying machine 1 of the present embodiment, the following effects are produced.
In the copying machine 1 of the present embodiment, in a stopped state, the leading end T1 of the paper T is once brought into contact with the registration roller pair 80 to bend the paper T, and then rotated to drive the paper T to the image forming unit GK. A pair of registration rollers 80 to be sent out, a conveyance roller 90 that conveys the paper T in the conveyance direction D1, and that can stop by bringing the leading end T1 of the paper T into contact with the registration roller pair 80 in a state where the paper T is sandwiched. The length in the direction D1 is set to be longer than the first guide length L1 and the first guide length L1 formed on the upstream side in the conveyance direction D1 of the registration guide member 130 in the curved paper T. In addition, the resist guide member 130 that is variable to the second guide length L2 that contacts the curved paper T so as to press the convex side of the curved shape, and the length of the resist guide member 130 are changed. Guide length changing unit 140 and guide length changing control for controlling the guide length changing unit 140 to change the length of the resist guide member 130 after the transfer material T comes into contact with the resist guide member 130. Unit 210.

  Therefore, after correcting the skew of the paper T with the front end pressing force at a predetermined length of the registration guide member 130, the front end pressing force is increased or decreased by changing the length of the registration guide member 130, so that the paper T Skew correction can be performed appropriately.

  Specifically, the front end pressing is performed by changing the length of the resist guide member 130 from the first guide length L1 where the front end pressing force of the paper T is small or the second guide length L2 where the front end pressing force is large. The power can be adjusted. Thus, after correcting the skew of the paper T with the leading edge pressing force at the first guide length L1 or the second guide length L2, the sheet is fed with the appropriate leading edge pressing force by changing the length of the resist guide member 130. T skew correction can be performed appropriately.

  For example, in the case of using the paper T with low rigidity (weak waist), the leading edge pressing force formed on the upstream side in the conveyance direction D1 of the registration guide member 130 by the curved convex shape of the paper T is reduced from the leading edge. The shortage of the pressing force can be resolved and the skew correction of the paper T can be suitably performed.

  Further, for example, when using a paper T having a high rigidity (strong stiffness), the leading edge T1 of the paper T is changed from a state in which the leading edge pressing force that contacts the curved convex side of the paper T is large. Is prevented from entering the registration nip RN, and skew correction of the paper T can be suitably performed.

  In the copying machine 1 according to the present embodiment, the registration guide member 130 includes two plate members 130a and 130b and conveys one of the first plate member 130a and the second plate member 130b. By sliding in the direction D1, the length in the transport direction D1 is variably configured. The guide length changing unit 140 changes the length of the registration guide member 130 in the transport direction D1 by sliding at least one of the first plate member 130a and the second plate member 130b in the transport direction D1. .

  Therefore, the length of the registration guide member 130 in the transport direction D1 can be changed with a simple configuration. Thereby, skew correction of the paper T can be suitably performed with a simple configuration.

  In the copying machine 1 according to the present embodiment, the guide length change control unit 210 is curved based on type information including thickness information about the thickness of the paper T and / or rigidity information about the rigidity of the paper T. The guide length is changed so that the length of the resist guide member 130 is set to the first guide length L1 when the convex shape of the curved sheet T is formed on the upstream side in the transport direction D1 of the resist guide member 130. After controlling the portion 140 to form the curved convex on the curved sheet T on the upstream side in the conveyance direction D1 of the registration guide member 130, the length of the registration guide member 130 is set to the second guide length L2. Thus, the guide length changing unit 140 is controlled.

  Therefore, when using a wide variety of sheets T having different thicknesses and rigidity, the length of the registration guide member 130 is changed so that it is not easily affected by the type of the sheet T, and the leading end T1 of the sheet T is a pair of registration rollers. It is possible to suitably adjust the tip pressing force when contacting 80. For example, by performing a button operation for selecting the type of the paper T to be used, the front end pressing force when the front end T1 of the paper T abuts against the registration roller pair 80 is suitably set based on the type information of the paper T. It is possible to adjust.

  The leading edge pressing force of the sheet T is the leading edge pressing force at the first guide length L1 (the leading end smaller than the second guide length L2) in a state where the leading end T1 of the sheet T is pressed toward the registration nip RN. From the pressing force) to the tip pressing force at the second guide length L2 (tip pressing force larger than the first guide length L1).

  Thus, after correcting the skew of the paper T with the leading edge pressing force at the first guide length L1 (the leading edge pressing force smaller than the second guide length L2), the leading edge pressing force at the second guide length L2 (first The skew correction of the paper T can be properly performed with a leading edge pressing force larger than one guide length L1.

  In particular, when the rigidity of the paper T is small, the skew correction of the paper T is performed with the front end pressing force at the first guide length L1 (the front end pressing force smaller than the second guide length L2), and then the second guide. By properly correcting the skew of the paper T with the leading edge pressing force at the length L2 (the leading edge pressing force larger than the first guide length L1), the shortage of the leading edge pressing force is eliminated and the skew correction of the paper T is performed. It can be suitably performed.

  As described above, it is possible to perform skew correction surely and appropriately even when various types (stiffness) of paper T are used by suppressing the skew correction due to insufficient tip pressing force. it can.

  Further, in the copier 1 in the present embodiment, the guide length change control unit 210 is based on the type information including the thickness information about the thickness of the paper T and / or the rigidity information about the rigidity of the paper T. When the convex side of the curved shape in FIG. 4 contacts the registration guide member 130, the guide length changing unit 140 is controlled so that the length of the registration guide member 130 becomes the second guide length L2, and the curved shape of the paper T After the convex side of the guide contacts the registration guide member 130, the guide length changing unit 140 is controlled so that the length of the registration guide member 130 is the first guide length L1.

  Therefore, when using a wide variety of sheets T having different thicknesses and rigidity, the length of the registration guide member 130 is changed so that it is not easily affected by the type of the sheet T, and the leading end T1 of the sheet T is a pair of registration rollers. It is possible to suitably adjust the tip pressing force when contacting 80. For example, by performing a button operation for selecting the type of the paper T to be used, the front end pressing force when the front end T1 of the paper T abuts against the registration roller pair 80 is suitably set based on the type information of the paper T. It is possible to adjust.

  The leading edge pressing force of the sheet T is the leading edge pressing force at the second guide length L2 (the leading end larger than the first guide length L1) in a state where the leading end T1 of the sheet T is pressed toward the registration nip RN. From the pressing force) to the tip pressing force at the first guide length L1 (tip pressing force smaller than the second guide length L2).

  Thus, after correcting the skew of the paper T with the tip pressing force at the second guide length L2 (tip pressing force greater than the first guide length L1), the tip pressing force (first pressing at the first guide length L1) The skew correction of the paper T can be properly performed with the tip pressing force smaller than the two guide lengths L2.

  In particular, when the rigidity of the paper T is large, the skew correction of the paper T is performed with the leading edge pressing force at the second guide length L2 (the leading edge pressing force larger than the first guide length L1), and then the first guide is corrected. By properly correcting the skew of the paper T with the front end pressing force at the length L1 (the front end pressing force smaller than the second guide length L2), the front end portion T1 of the paper T is prevented from entering the registration nip RN. Thus, the skew correction of the paper T can be suitably performed.

  As described above, it is possible to perform skew correction surely and appropriately even when various types (stiffness) of paper T are used by suppressing skew correction due to excessive tip pressing force. it can.

As mentioned above, although preferred embodiment of this invention was described, this invention can be implemented with a various form, without being limited to embodiment mentioned above.
For example, in the above-described embodiment, the guide length changing unit 140 drives the guide length changing driving unit 149 to move the second plate member 130b of the registration guide member 130 in the transport direction D1 to increase the guide length. It has changed, but is not limited to this. For example, the guide length changing unit 140 drives the guide length changing driving unit 149 to move the pin member 135 along the first through long hole 133 and the second through long hole 134 so that the resist guide member 130 The second plate member 130b may be moved in the transport direction D1.

  In the above-described embodiment, the guide length changing drive unit 149 is configured by a solenoid and the second plate member 130b of the registration guide member 130 is moved by the solenoid. However, the present invention is not limited to this. For example, the guide length change drive unit 149 may be configured by a motor, and the second plate member 130b of the resist guide member 130 may be moved by the motor.

  In the above-described embodiment, the guide length change control unit 210 is configured to control the guide length change unit 140 based on information such as the rigidity of the paper T stored in the storage unit 250. This is not a limitation. For example, the guide length change control unit 210 acquires information such as the rigidity of the paper T by detecting the size of the curved shape formed on the paper T with a sensor or the like, and based on this information, the guide length change It is good also as a structure which controls the length change part 140. FIG.

In the above-described embodiment, the resist guide member 130 is configured by the two plate members 130a and 130b. However, the present invention is not limited to this. The resist guide member 130 may be composed of, for example, three or more plate members.
The type of the image forming apparatus of the present invention is not particularly limited, and may be a copier, a printer, a facsimile, or a complex machine thereof.
Further, the sheet-like transfer material is not limited to paper, and may be a film sheet, for example.

  DESCRIPTION OF SYMBOLS 1 ... Copy machine (image forming apparatus), 80 ... Registration roller pair, 90 ... 1st conveyance roller pair (conveyance roller), 130 ... Registration guide member (guide member), 140 ... Guide length change part , 210... Guide length change control unit, T... Paper (transfer material), T1 .. tip end, RN .. registration nip, GK.

Claims (4)

An image forming unit for forming an image on a sheet-like transfer material;
A pair of registration rollers that form a registration nip, and in a stopped state, the tip of the material to be transferred is once brought into contact with the pair of registration rollers to bend the material to be transferred, and then rotated to drive the material to be transferred. A pair of registration rollers for feeding the material to the image forming unit;
The registration roller pair is disposed upstream of the transfer material in the conveyance direction, conveys the transfer material in the conveyance direction, and holds the transfer material in a state where the tip of the transfer material is nipped. A transport roller that can be stopped by contacting the registration roller pair;
A guide member that is disposed between the pair of registration rollers and the conveyance roller and guides the material to be transferred to the registration nip, wherein the length in the conveyance direction is curved in the curved shape of the material to be transferred. A first guide length formed on the upstream side in the conveying direction of the guide member, and a curved convex side pressed against the material to be transferred which is longer than the first guide length and is curved. A guide member that is variable according to the second guide length in contact;
A guide length changing section for changing the length of the guide member to the first guide length and the second guide length;
A guide length change control unit for controlling the guide length changing unit to change the length of the guide member after the transfer material comes into contact with the guide member when the registration roller pair is stopped; ,
An image forming apparatus comprising: The guide member is composed of a plurality of plate members, and is configured to be variable in length in the transport direction by sliding at least one of the plurality of plate members in the transport direction,
The image forming apparatus according to claim 1, wherein the guide length changing unit changes the length of the guide member in the transport direction by sliding at least one of the plurality of plate members in the transport direction. The guide length change control unit is configured to bend the curved shape of the transferred material based on the type information including the thickness information related to the thickness of the transferred material and / or the rigidity information related to the rigidity of the transferred material. When the convex portion is formed on the upstream side in the conveying direction of the guide member, the guide length changing portion is controlled so that the length of the guide member is the first guide length, and the curved portion is curved. After the curved convex portion of the transfer material is formed on the upstream side in the conveying direction of the guide member, the guide length changing unit is controlled so that the length of the guide member is the second guide length. The image forming apparatus according to claim 1. The guide length change control unit is configured to determine whether the convex side of the curved shape of the transfer material is based on type information including thickness information about the thickness of the transfer material and / or rigidity information about the rigidity of the transfer material. When abutting on the guide member, the guide length changing unit is controlled so that the length of the guide member is the second guide length, and the curved convex side of the transfer material is placed on the guide member. 3. The image forming apparatus according to claim 1, wherein after the contact, the guide length changing unit is controlled so that the length of the guide member is the first guide length. 4.

Images