JP4701993B2 - Curling straightener - Google Patents

Description

  The present invention relates to a curl correction apparatus.

In an image forming apparatus using an electrophotographic technology, an electrostatic latent image formed on an image carrier is developed with a developer, and a toner image obtained by the development is transferred onto a sheet, and then passed through a fixing heating roll or the like. It is well known that an image is formed by fixing a toner image, and the paper curls when the toner image is fixed. There are two directions for curling. The phenomenon of curling upward is called "upper curl", and the phenomenon of curling downward is called "down curl". Whether the curl generated on the paper becomes an upper curl or a down curl depends on various conditions such as the paper quality of the paper and the density of the toner image.
As a mechanism for correcting the curl generated at the fixing stage, the techniques of Patent Documents 1 and 2 have been devised. Many of this type of mechanism, like the curl correction apparatus described in Patent Document 1, are provided with two separate conveyance paths: a correction conveyance path that corrects upper curl of paper and a correction conveyance path that corrects down curl. In addition, a sheet on which the toner image has been fixed is supplied to one of the correction conveyance paths selected according to the type of the sheet. On the other hand, Patent Document 2 also discloses a mechanism for performing upper curl correction and down curl correction using one correction conveyance path. The curl correction apparatus described in this document overlaps two belts facing each other as a correction conveyance path, and further sandwiches the two overlapped belts by two variable rolls movable in the vertical direction. When the upper roll is corrected, the belt is bent downward by moving the variable roll downward. On the other hand, when the down roll is corrected, the belt is bent upward by moving the variable roll upward. Yes.
JP-A-6-156852 Japanese Patent Laid-Open No. 6-165049

However, the proposed mechanism has the following problems. First, the curl correction apparatus of the type described in Patent Document 1 has to have two correction conveying paths for upper curl and down curl, so the apparatus configuration has to be large. . On the other hand, the curl correction apparatus described in Patent Document 2 requires only one correction conveyance path, so that the apparatus configuration can be made relatively small. The driving load on the belt was inevitably increased.
The present invention has been devised under such a background, and an object of the present invention is to provide a mechanism capable of correcting paper curl with a space-saving, low-noise and low-load configuration.

A curl correction device according to a preferred aspect of the present invention is a curl that is interposed between a toner fixing mechanism and a paper discharge port, corrects the curl of the paper after the toner image is fixed by the toner fixing mechanism, and supplies the curl to the paper discharge port. a correction apparatus, a housing, a movable roll to move by the amount specified in the first direction and a second direction opposite, wound fixed roll and wound which is fixed to the housing a belt, a first belt and curl correction conveyance path formed by the combined I heavy driving surfaces of the second belt, for each of the first and second belts, winding one belt The curled correction conveying path in which the movable roll is opposed to the driving surface of the other belt at a position away from both ends in the driving direction of the belt by a predetermined amount, and the paper unloaded from the toner fixing mechanism. Entrance leading to the entrance of the straightening conveyance path A guide chute, and the outlet side guide chute for guiding the sheet fed out from the outlet to the outlet through the curl correction conveyance path, towards the movable roll of the first which has wound the first belt with curving the driving surface of the second belt to the moving direction by moving by a predetermined amount to the direction, it is moved by a predetermined amount movable roll by winding the second belt to said first direction the first by moving a predetermined amount of the movable roll to the second direction turning the first correction mode and, winding said second belt substantially linearly driving surface of the first belt by the driving surface of one of the belt with curving to the moving direction, the driving of the second belt by said first movable roll belt is wound to be moved by a predetermined amount in the second direction The and a straightening mode switching control means for switching a second correction mode in which substantially linearly.

  According to the present invention, it is possible to provide a mechanism that can correct paper curl with a space-saving, low-noise, and low-load configuration.

(Embodiment of the Invention)
An embodiment of the present invention will be described.
FIG. 1 is a diagram illustrating a configuration of a curl correction apparatus according to the present embodiment and an image forming apparatus that carries out printed paper to the correction apparatus. The image forming apparatus 10 shown in the figure forms a toner image on an image carrier such as a photosensitive drum and transfers the toner image onto a sheet, and then passes the fixing unit 11 to fix the toner image on the sheet. The curl correction device 20 is interposed between the fixing unit 11 of the image forming apparatus 10 and the paper discharge tray for printed paper, corrects curl generated on the paper passing through the fixing unit 11, and then discharges itself. The paper is discharged from the paper slot 95. The curl correction apparatus 20 is configured to set a curl of a sheet supplied from the image forming apparatus 10 according to a belt nip method, and a setting unit 30 that is an operator for setting whether the type of curl to be corrected is an upper curl or a down curl. A box-shaped casing 91 is provided with a curl correction unit 40 for correction and a correction mode switching control unit 90 for controlling the operation of the curl correction unit 40 according to the setting of the setting unit 30. Here, “upper curl” means to curl in a concave shape so that both ends of the paper that has undergone toner image fixing are raised upward, and “down curl” means that the center of the paper that has undergone toner image fixing is upward. It means curling in a convex shape to lift.

  The configuration of the curl correction unit 40 will be described in detail with reference to FIG. As shown in the figure, this unit 40 has a belt nip 41 serving as a conveying path for correcting curl by partially overlapping a lower belt 51 and an upper belt 71, each of which is swiveled by two rolls. Formed. In the following description, the surfaces of both belts forming the belt nip 41 are appropriately referred to as “drive surfaces”.

  First, the lower belt 51 and its drive system will be described in detail. The lower belt 51 is moved up and down under the control of the drive roll 52 fixed to the housing 91 and the correction mode switching control unit 90 shown in FIG. It is wound between driven rolls 53 that move in both directions. The drive roll 52 receives the rotational force of the motor 54 and rotates clockwise, thereby driving the lower belt 51 that is turned by itself. Further, a driven roll 53 obtained by turning the lower belt 51 together with the drive roll 52 is formed by connecting one end of a link member 56 and an inlet side guide chute 57 to an axis 55 thereof.

  The link member 56 is a member for interlocking the driven roll 53 with a displacement mechanism 58 that moves the position up and down. The displacement mechanism 58 is fixed downward at a predetermined distance from a cam member 59 pivotally supported on the other end of the link member 56, a motor 60 that rotates the cam member 59, and a cam shaft 62 of the cam member 59. And a cam driven member 61. When the cam member 59 of the displacement mechanism 58 is rotated by receiving the rotational force of the motor 60 and the distance between the cam shaft 62 and the cam driven member 61 in the cam member 59 increases, the link member 56 winds the lower belt 51. It is pushed upward together with the driven roller 53. On the other hand, when the distance between the cam shaft 62 and the cam driven member 61 in the cam member 59 becomes smaller, the link member 56 is pushed down together with the driven roll 53.

  The entrance-side guide chute 57 is a member that guides the sheet transported from the fixing unit 11 of the image forming apparatus 10 to the entrance of the belt nip 41, and has a plate shape whose vertical width is slightly smaller than the diameter of the driven roll 53. Is made. As described above, one end of the guide chute 57 is connected to the shaft center 55 of the driven roll 53, and the other end is provided with a long hole 64 through which the guide support bar 63 is inserted. . The guide support bar 63 is a rod-shaped member whose both ends are fixed to the housing 91 in order to support the guide chute 57. Further, the guide support bar 63 is urged toward the inside of the chute 57 by a spring 65. The entrance-side guide chute 57 having such a structure is interlocked with the vertical movement of the driven roll 53 and supports the support bar 63 while sliding the contact portion with the guide support bar 63 back and forth appropriately against the force of the spring 65. Swings up and down around the fulcrum. By this swinging, the sheet conveyed from the fixing unit 11 regardless of the position of the driven roll 53 is guided to the entrance of the belt nip 41.

  Next, the upper belt 71 and its drive system will be described in detail. The upper belt 71 and its drive system are substantially the same as the lower belt 51 and its drive system, except that the positional relationship between the upper and lower sides and the front and rear is reversed. That is, the upper belt 71 is swung between the drive roll 72 and the driven roll 73, and the drive roll 72 receives the rotational force of the motor 74 and rotates clockwise, while the shaft center 75 of the driven roll 73 is a cam member. 79, a link mechanism 76 and a displacement mechanism 78 including a motor 80 and a cam driven member 81, and further, a curled sheet that is unloaded from the exit via the belt nip 41 is guided to the discharge port 95. The outlet side guide chute 77 is also connected.

The operation of this embodiment will be described.
The operation of this embodiment can be divided into an operation in the upper curl correction mode and an operation in the down curl correction mode. When the setting unit 30 sets the upper curl correction mode, the correction mode switching control unit 90 controls the operation of each part of the curl correction unit 40 according to the procedure according to the upper curl correction mode. Is set, the operation of each part is controlled in accordance with the procedure according to the down-roll correction mode.

  FIG. 3 is a diagram illustrating an operation in the upper curl correction mode. In the upper curl correction mode, the correction mode switching control unit 90 moves the driven rolls 53 and 73 upward by a predetermined amount through the rotation of the motors 60 and 80, respectively, thereby driving the driven roll 53. Curving upward the driving surface of the upper belt 71 that is in contact with the lower belt 51 and the driving surface of the lower belt 51 in which the driven roll 73 is in contact with the upper belt 71 in between. To. The amount of movement of the driven roll 73 for making the drive surface of the lower belt 51 substantially linear is optimized according to the distance between the two driven rolls 53 and 73 and the amount of movement of the driven roll 53. For example, when the driven roll 73 is just in contact with the driving surface of the lower belt 51 with the upper belt 71 in between, the movement amount of the driven roll 73 is reduced to half the movement amount of the driven roll 53. The belt 51 can be made substantially linear. When the upper curled paper is carried into the belt nip 41 where the upper belt 71 is curved upward and the lower belt 51 is substantially linear, the belt nip 41 is an overlapping portion of both belts. After passing through the curved portion near the entrance, it is corrected downward and then guided to the exit side guide chute 77 and carried out to the discharge port 95.

  FIG. 4 is a diagram illustrating an operation in the down curl correction mode. In the down curl correction mode, the correction mode switching control unit 90 moves the driven rolls 53 and 73 downward by a predetermined amount through rotation of the motors 60 and 80, respectively, so that the driven roll 73 sandwiches the upper belt 71. The driving surface of the lower belt 51 in contact is curved downward, and the driving surface of the upper belt 71 in contact with the driven roll 53 with the lower belt 51 in between is made substantially linear. When the down-curled paper is carried into the belt nip 41 where the lower belt 51 is curved downward and the upper belt 71 is substantially linear, the paper is placed in the belt nip 41. After being corrected upward when passing through a curved portion near the outlet, the lead is guided to the outlet guide chute 77 and carried to the discharge port 95.

  According to the present embodiment described above, in the upper curl correction mode, the driving surface of the upper belt 71 with which the driven roll 53 is in contact with the lower belt 51 is curved upward, so that the upper curled paper is used. A flat state can be corrected by passing through the curved portion. Furthermore, since the lower belt 51 with which the driven roll 73 is in contact with the upper belt 71 is made substantially linear, it is possible to prevent the corrected paper from returning to the curled state again. On the other hand, in the down curl correction mode, the drive surface of the lower belt 51 with which the driven roll 73 is in contact with the upper belt 71 is curved downward, so that the down curled paper is flattened by passing through the curved portion. Can be corrected. Further, since the upper belt 71 with which the driven roll 53 is in contact with the lower belt 51 is made substantially linear, it is possible to prevent a situation where a stronger curl is applied before correction is made. .

(Other embodiments)
The present invention can be modified in various ways.
For example, in the above-described embodiment, the user himself / herself has to perform through the setting unit 30 whether to perform the operation in the upper curl correction mode or the operation in the down curl correction mode. On the other hand, the correction mode may be automatically specified according to the type of paper to be corrected. This modification is realized by including a curl type storage memory in which attribute information indicating attributes of various types of paper is associated with curl type information indicating upper curl or down curl. In this modification, when the user sets the type of paper to be corrected via the setting unit 30, the correction mode switching control unit 90 stores the curl type information stored in the memory in association with the type information of the type. The curl correction unit 40 is controlled according to the mode indicated by.

  Further, not only the correction mode but also the correction amount in these modes, that is, the degree of curvature of the belt, may be automatically specified according to the type of paper. This modification is a movement amount storage that stores attribute information indicating attributes of various types of paper and movement amount information indicating the movement amount of the movable roll when correcting the curl of the paper having these attributes in association with each other. This is realized by further providing a memory. In this modification, the correction mode switching control unit 90 associates each movable roll with the movement amount indicated by the movement amount information indicated by the movement amount storage memory in association with the attribute information of the attribute set by the user via the setting unit 30. The degree of curl correction is controlled by moving 55 and 75.

It is a figure which shows the structure of a curl correction apparatus and an image forming apparatus. It is a figure which shows the detailed structure of a curl correction unit. It is a figure which shows the operation | movement at the time of upper curl correction mode. It is a figure which shows the operation | movement at the time of down curl correction mode.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Fixing unit, 20 ... Curl correction apparatus, 30 ... Setting part, 40 ... Curl correction unit, 41 ... Belt nip, 51 ... Lower belt, 52, 72 ... Drive roll, 53, 83 ... Driven roll, 54, 60 , 74, 80 ... motor, 55, 75 ... axial center, 56, 76 ... link member, 57 ... inlet side guide chute, 58, 78 ... displacement mechanism, 59 ... cam member, 61 ... cam follower member, 62 ... cam shaft 63 ... Guide support bar, 63 ... Guide support bar, 64 ... Elongated hole, 65 ... Spring, 71 ... Upper belt, 72 ... Drive roll, 73 ... Driving roll, 77 ... Exit side guide chute, 79 ... Cam member, 81 ... Cam driven member, 90 ... Correction mode switching control unit, 91 ... Housing, 95 ... Paper discharge port

Claims (1)

A curl correction device interposed between the toner fixing mechanism and the paper discharge port, for correcting the curl of the paper after the toner image is fixed by the toner fixing mechanism and supplying the curl to the paper discharge port;
A housing,
A movable roll moves by specified amount to the first direction and the second direction opposite a fixed roll and wound on the belt which is fixed to the housing, first and first belt the driving surfaces of the second belt a curl correcting conveying path formed by mating it heavy, for each of the first and second belts, the movable roll in which is wound one of the belt, the other belt A curl correction conveyance path facing the driving surface at a position away from the both ends in the driving direction of the belt by a predetermined amount ;
An inlet-side guide chute that guides the paper carried out of the toner fixing mechanism to the inlet of the curl correction conveyance path;
An exit-side guide chute that guides the paper carried out from the exit via the curl correction conveyance path to the discharge port;
With curving the driving surface of the second belt to the moving direction by moving a predetermined amount of the movable roll by winding the first belt to the first person direction, the second belt a first correction mode for substantially linearly driving surface of the first belt by causing the movable roll is wound in the first direction is moved by a predetermined amount, winding a second belt the driving surface of the first belt by moving a predetermined amount of the movable roll in the second direction with curving to the movement direction, the first belt wound movable roll the second was A curl straightening device comprising: a straightening mode switching control means for switching between a second straightening mode in which the driving surface of the second belt is made substantially linear by moving in a direction by a predetermined amount.

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