JP2008112102A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To cool paper after fixing efficiently and without having it curl. <P>SOLUTION: An image forming apparatus has the paper 18 closely held between belts 66 provided in a pair of cooling parts 62 and 64. Furthermore, metal members 70 are installed on inner sides of the belts to speedily absorb heat received by the belt 66 from the paper 18 and discharge it. In addition, the belts 66 holding the paper 18 is conveyed on a plane. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus.

In Patent Document 1, it is proposed that a belt is wound around a drum, a sheet is sandwiched between the winding portions, and cooling is performed.
Japanese Patent No. 3682982

  An object of the present invention is to obtain an image forming apparatus that can efficiently cool a sheet after fixing in consideration of the above facts.

  According to the first aspect of the present invention, there is provided a fixing unit that fixes a developer by heating the recording medium on which the developer is transferred, and a recording medium on which the developer is fixed by the fixing unit. It has a conveying means for conveying at least one surface in surface contact, and a cooling means for cooling the conveying means.

  According to a second aspect of the present invention, in the first aspect of the present invention, the conveying means has an endless annular member and is arcuate or planar.

  According to a third aspect of the present invention, in the first aspect of the invention, the cooling means includes an endless annular member that circulates while being in surface contact with the recording medium, and a rear surface side of the surface where the recording medium is in surface contact. And a cooling member that cools in contact with each other.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the cooling means closely contacts the upper surface in the vertical direction of the recording medium being conveyed to the endless annular member. It is characterized by having a close contact member.

  According to a fifth aspect of the invention, in the invention of the fourth aspect, the storage medium is normally in a non-contact state facing the lower surface in the vertical direction of the recording medium that is in close contact with the endless annular member. A guide plate is arranged.

  A sixth aspect of the invention is characterized in that, in the invention of the fourth or fifth aspect, air for cooling is blown from the lower surface in the extending direction of the recording medium in close contact with the endless annular member. It is said.

  A seventh aspect of the invention is characterized in that, in the sixth aspect of the invention, a direction in which the cooling air flows is an acute angle with respect to a conveyance direction of the recording medium.

  According to the first aspect of the present invention, it is possible to cool the recording medium after the fixing so as not to cause curl wrinkles more efficiently than when the present invention is not provided.

  According to the second aspect of the present invention, good adhesion between the recording medium and the endless annular member can be realized.

  According to the invention described in claim 3, since the cooling is performed on the back surface side where the recording medium of the endless annular member comes into surface contact, the cooling can be performed more efficiently.

  According to the fourth aspect of the present invention, since the upper surface of the recording medium is brought into close contact with the endless annular member and the lower surface of the recording medium becomes a space, the cooling effect can be increased or decreased.

  According to the fifth aspect of the present invention, there is a possibility that the recording medium may fall off only with the holding force when the recording medium is brought into close contact with the contact means. Therefore, a guide plate that is normally in a non-contact state with respect to the paper can be prepared for unexpected situations such as dropping of the paper during the cooling process.

  According to the sixth aspect of the present invention, the upper surface of the recording medium is cooled by bringing an endless annular member into close contact, and at the same time, cooling air is blown from the lower surface of the recording medium, thereby further effectively cooling. be able to.

  According to the seventh aspect of the present invention, the cooling air does not become a resistance for conveying the recording medium.

  FIG. 1 shows an image forming apparatus 10 according to the present exemplary embodiment.

  In the image forming apparatus 10, the image processing unit 12 is arranged at the center. A paper feed unit 14 is provided on the left side of the image processing unit 12 in FIG. Further, a post-processing unit 16 is provided on the right side of the image processing unit 12 in FIG.

  Between the image processing unit 12 and the paper supply unit 14, a guide unit 20 that guides the conveyance of the paper 18 that is an example of a recording medium is interposed. Other examples of the recording medium include an OHP sheet and a coated paper.

  On the upper part of the guide unit 20, a display and operation unit 22 is provided that can display information and indicate the displayed content by touching the information display area with a finger or the like. The display / operation unit 22 is generally referred to as a “touch panel” and serves as a user interface that mediates the exchange of information between the user and the image forming apparatus 10.

  The image processing unit 12 includes image forming units 24Y, 24M, 24C, and 24K for image formation of Y (yellow), M (magenta), C (cyan), and K (black) colors. They are arranged in a horizontal row in FIG. The image forming units 24Y, 24M, 24C, and 24K have the same configuration, 26 is an optical scanning device that outputs a light beam according to image data, 28 is a photosensitive drum on which an electrostatic latent image is formed by the light beam, 30 Is a transfer roller constituting the first transfer section 32. In addition, a charging unit, a developing unit, and a cleaning unit (not shown) are provided around the photosensitive drum 28. The charging unit uniformly charges the photosensitive drum 28. The developing unit supplies a two-component developer (toner and carrier) to the electrostatic latent image. The cleaning unit removes residual toner.

  A lower portion of the photosensitive drum 28 is a first transfer unit 32 and faces an endless intermediate transfer belt 34.

  The intermediate transfer belt 34 moves while being in contact with the photosensitive drums 28 of the image forming units 24Y, 24M, 24C, and 24K. Note that the intermediate transfer belt 34 is actually wound around the photosensitive drum 28 by the elastic force of the intermediate transfer belt 34 itself, the tension applied to the intermediate transfer belt 34, the pressure from the transfer roller 30, and the like. It touches with a width.

  The intermediate transfer belt 34 is wound around four rollers 36, circulates in the opposite direction in the order of the image forming units 24Y, 24M, 24C, and 24K, and the image is formed in the order of the image forming units 24Y, 24M, 24C, and 24K. Are superimposed and transferred. As a result, a so-called full-color image in which four color images are superimposed is transferred onto the intermediate transfer belt 34. In addition to a full-color image, it is possible to transfer a single color or an image of two or more colors, but in the present embodiment, the transfer image is hereinafter referred to as a “full-color image”.

  In this embodiment, the image forming units 24Y → 24M → 24C → 24K are sequentially arranged from the upstream side in the conveyance direction of the intermediate transfer belt 34 (the right side in FIG. 1). However, this order is not limited.

  The full color image on the intermediate transfer belt 34 is transferred to the paper 18 in the second transfer unit 38.

  The paper 18 is selectively taken out from a plurality of trays 40 (two in FIG. 1) provided in the paper supply unit 14, and a plurality of conveying roller pairs 42 and a plurality of belt conveyors are guided via the guide unit 20. 44 is guided to the conveyance path of the image processing unit 12. The end of the transport roller pair 42, which is the first half of the transport path, is the second transfer section 38, the paper 18 is brought into close contact with the intermediate transfer belt 34, and the full color image is transferred.

  The sheet 18 on which the full-color image has been transferred is sent out to the fixing unit 46 by the belt conveyor 44 which is the latter half of the conveyance path.

  The fixing unit 46 includes a heating roller 48 and a pressure roller 50, and the sheet 18 is guided between the heating roller 48 and the pressure roller 50, and a predetermined heat is applied under a predetermined pressure. Then, the toner that is a developer of the full-color image is fixed on the paper 18.

  The paper 18 fixed by the fixing unit 46 is sent to the post-processing unit 16.

  The post-processing unit 16 includes a cooling device 52, a sheet reversing mechanism unit 54, and a discharge tray 56.

  The sheet 18 discharged from the fixing unit 46 is first removed from the heat applied by the fixing unit 46 by the cooling device 52.

  The sheet 18 discharged from the cooling device 52 is discharged to the discharge tray 56 as it is when an image is formed on only one side.

  On the other hand, when the paper 18 discharged from the cooling device 52 forms an image on both sides, it is reversed by the paper reversing mechanism 54 and conveyed along the reverse conveying path 58 provided below the image processing unit 12. Returned to the guide unit 20 and sent again to the conveyance path of the image processing unit 12.

  As shown in FIG. 2, the cooling device 52 includes a receiving guide portion 60 that receives the paper 18 discharged from the fixing portion 46. By this receiving guide part 60, the paper 18 is fed between the cooling parts 62 and 64 facing the front and back surfaces of the paper, respectively.

  The belt 66 may be made of a material having excellent heat conductivity, and may be any other material that can form a thin plate such as a polyimide film, a nickel electroformed film, or a polyethylene film.

  Each of the cooling units 62 and 64 includes an endless belt 66, four rollers 68 that rotate the belt 66 in a substantially trapezoidal shape, and a metal member 70 that is a cooling unit disposed in an inner space of the belt 66. ing.

  For this reason, when the belts 66 of the upper and lower cooling units 62 and 64 are in planar contact with each other and the paper 18 is fed, the paper 18 is sandwiched between the belts 66 in contact with the flat surface, Both the front surface and the back surface of the paper 18 are conveyed in surface contact with the belt 66. Due to this surface contact, the heat of the paper 18 is transmitted to the belt 66 and is radiated through the metal member 70.

  That is, the metal member 70 is formed with a plurality of narrow grooves, and has a surface area larger than that of a normal box. As a result, the heat dissipation effect is increased. The metal member 70 has a role similar to that of a member normally called “heat sink” that absorbs and dissipates heat generated from electronic components such as ICs and transistors.

  The operation of this embodiment will be described below.

  When an image formation instruction is operated from the display / operation unit 22, the image processing unit 12 obtains image data, and based on this image data, from the optical scanning devices 26 of the image forming units 24Y, 24M, 24C, and 24K. The photosensitive drum 28 is irradiated with a light beam to form an electrostatic latent image, and toner development is performed by supplying a two-component developer from the developing unit.

  The toner image is transferred to the intermediate transfer belt 34 by the first transfer unit 32 so that the respective colors overlap each other, thereby forming a full-color image.

  The full color image is sent to the second transfer unit 38 as the intermediate transfer belt 34 is driven.

  On the other hand, in the paper feeding unit 14, the corresponding tray 40 is selected based on the size instructed by the display / operation unit 22, the paper 18 is taken out, and the conveyance path of the image processing unit 12 through the guide unit 20. Sent to.

  The sheet 18 is sent to the second transfer unit 38 by the conveyance roller pair 42 which is the first half of the conveyance path, and the intermediate transfer belt 34 is brought into contact with a predetermined pressure, and a transfer bias is applied. The image is transferred from the transfer belt 34 to the paper 18.

  Thereafter, the paper 18 is conveyed by the belt conveyor 44 which is the latter half of the conveyance path and reaches the fixing unit 46.

  In the present embodiment, the paper 18 is sandwiched and adhered between the belts 66 provided in the pair of cooling units 62 and 64.

  Further, a metal member 70 is disposed inside the belt 66, and the heat received by the belt 66 from the paper 18 is quickly absorbed and radiated.

  Further, the belt 66 sandwiching the paper 18 is transported in a plane.

  In the above embodiment, at least the belt 66 in the region sandwiching the paper 18 is transported in a plane, but it may be transported in a circular arc with a predetermined radius of curvature that does not cause wrinkles. This circular conveyance is intended to improve the adhesion between the paper 18 and the belt 66.

  In the above embodiment, in the cooling device 52, the cooling units 62 and 64 are arranged on both the front and back surfaces of the paper 18, and the paper 18 is sandwiched between the pair of belts 66. Since the toner immediately after fixing by the fixing unit 46 does not exist in the lower surface in FIG. 2 (in the case of both surfaces, the lower surface passes through the cooling device 52 as the upper surface in the previous round), and therefore, the upper surface is intensively cooled. A configuration may be adopted.

  The modifications are listed below.

(Modification 1)
As shown in FIG. 3, in the first modification, an adhesion promotion roll 72 is provided at the terminal end (downstream side in the transport direction) of the receiving guide portion 60. The sheet 18 is in close contact with the belt 66 by the adhesion promotion roll 72, so that the sheet 18 itself maintains the contact state. In this case, since the holding force is reduced on the downstream side in the conveyance direction of the region in close contact with the belt 66, a guide plate 74 that is normally not in contact with the paper 18 may be provided.

(Modification 2)
As shown in FIG. 4, in the second modified example, in addition to the first modified example, a guide plate 76 that is not in contact with the paper 18 is arranged in the entire area facing the belt 66 to which the paper 18 is in close contact. In this configuration, a hole is provided in the fan and cooling air is blown by driving the fan 78. Thereby, the back side of the paper 18 can be appropriately cooled.

(Modification 3)
As shown in FIG. 5, Modification 3 is a structure in which the fan 78 is inclined with respect to the structure of Modification 2, and the direction of the cooling air from the fan 78 is an acute angle with respect to the conveyance direction of the paper 18. . As a result, the cooling air is blown so that the paper 18 is unlikely to fall off the belt 66.

(Modification 4)
As shown in FIG. 6, in the fourth modification, the direction of the cooling air is changed with respect to the sheet 18 by the auxiliary guide plate 80 provided on the guide plate 76 without tilting the fan 78 with respect to the configuration of the third modification. It is a configuration with an acute angle.

1 is a schematic configuration diagram of an image forming apparatus according to the present embodiment. It is an enlarged front view of a cooling device. It is a front view of the cooling device concerning modification 1. It is a front view of the cooling device concerning modification 2. It is a front view of the cooling device concerning modification 3. It is a front view of the cooling device concerning modification 4.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 12 Image processing part 14 Paper feed part 16 Post-processing part 18 Paper 20 Guide part 22 Display and operation part 24Y, 24M, 24C, 24K Image forming part 26 Optical scanning device 28 Photosensitive drum 30 Transfer roller 32 1st Transfer section 34 Intermediate transfer belt 36 Roller 38 Second transfer section 40 Tray 42 Conveying roller pair 44 Belt conveyor 46 Fixing section 48 Heating roller 50 Pressure roller 52 Cooling device 54 Paper reversing mechanism section 56 Discharge tray 58 Reverse transport path 60 Accepting guide Part 62, 64 cooling part 66 belt 68 roller 70 metal member

Claims (7)

Fixing means for fixing the developer by heating the recording medium to which the developer has been transferred;
A conveying unit that conveys at least one surface of the recording medium in contact with the recording medium having the developer fixed by the fixing unit;
Cooling means for cooling the conveying means;
An image forming apparatus comprising:   The image forming apparatus according to claim 1, wherein the conveying unit includes an endless annular member and has an arc shape or a planar shape.   The cooling means includes an endless annular member that circulates while being in surface contact with the recording medium, and a cooling member that contacts and cools on the back surface side of the surface with which the recording medium is in surface contact. The image forming apparatus according to 1.   4. The image forming apparatus according to claim 1, wherein the cooling unit includes a contact member that closely contacts an upper surface in a vertical direction of a recording medium conveyed to the endless annular member. 5. .   5. The image forming apparatus according to claim 4, wherein a guide plate is provided so as to face the lower surface in the vertical direction of the recording medium that is in close contact with the endless annular member. apparatus.   6. The image forming apparatus according to claim 4, wherein air for cooling is blown from a lower surface in an extending direction of the recording medium that is in close contact with the endless annular member.   The image forming apparatus according to claim 6, wherein a direction in which the cooling air flows is an acute angle with respect to a conveyance direction of the recording medium.

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