JP2008112103A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prolong the cooling time, without having to make the length of a conveyance path for cooling larger, while maintaining a conveying speed up to fixing processing. <P>SOLUTION: Upper and lower two-stage structure cooling devices 52 and 53 are arranged, and a movable guide section 60A to alternatively guide a paper 18 is provided. When the first paper 18 is discharged from a fixing section 46, the first paper 18 is guided to the upper cooling device 52. After that, when the second paper 18 is discharged from the fixing section 46, the movable guide section 60A is switched, to guide the second paper 18 to the lower cooling device 53. Since the first paper 18 can be held in the upper cooling device 52 for the time of guiding the second paper 18 to the lower cooling device 53, the cooling time can be secured. <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 recording medium is sandwiched between the wound portions, and cooling is performed.
Japanese Patent No. 3682982

  In consideration of the above-described facts, the present invention provides a cooling device and an image forming apparatus capable of extending the cooling time while maintaining the conveyance speed until the fixing process and without increasing the conveyance path length for cooling. Is the purpose.

  According to the first aspect of the present invention, there is provided fixing means for fixing the developer by heating the recording medium to which the developer has been transferred, and the recording medium on which the developer has been fixed by the fixing means to a plurality of conveyance paths. The distribution unit and the recording medium distributed to the plurality of conveyance paths by the distribution unit are cooled in a time that remains on the plurality of conveyance paths.

  According to a second aspect of the present invention, there is provided fixing means for fixing the developer by heating the recording medium to which the developer has been transferred, and the recording medium on which the developer has been fixed by the fixing means to a plurality of conveyance paths. The distribution unit includes a distribution unit, and a cooling unit that cools the recording medium in a conveyance path distributed by the distribution unit.

  The invention described in claim 3 is the invention described in claim 2, characterized in that the cooling means is provided in each of the transport paths distributed by the distribution means.

  According to a fourth aspect of the present invention, in the invention of the second or third aspect, the cooling means contacts an endless annular member that circulates while being in surface contact with the recording medium, and the endless annular member. And a cooling member for cooling.

  The invention according to claim 5 is the invention according to claim 2 or claim 3, wherein the cooling means is in surface contact with the endless annular member that circulates while making surface contact with the recording medium. And a cooling member that contacts and cools on the back side of the surface.

  The invention according to claim 6 is the invention according to any one of claims 1 to 5, wherein the order of the recording media discharged from the fixing unit is a plurality of conveying paths by the distributing unit. It is characterized by the same order after being sorted and cooled.

  The invention according to claim 7 is the invention according to any one of claims 1 to 6, wherein the number of use of a plurality of transport paths is determined by the thickness or material of the recording medium. It is said.

  According to the first aspect of the present invention, the recording medium after fixing can be cooled more efficiently than in the case where the present invention is not adopted because it remains on the conveyance path.

  According to the second aspect of the present invention, compared to the first aspect of the invention, the recording medium after fixing can be efficiently cooled by employing the cooling means.

  According to the third aspect of the present invention, it is possible to cool the recording medium after fixing more efficiently by adopting the cooling means for each of the conveyance paths as compared with the case where the present invention is not adopted.

  According to the fourth aspect of the present invention, compared to the case where the present invention is not adopted, the cooling means is in contact with the endless annular member and efficiently dissipates heat from the endless annular member, so that the recording medium after fixing is cooled. be able to.

  According to the invention described in claim 5, compared with the case where the present invention is not adopted, the cooling means is provided inside the endless annular member, which can contribute to space saving and efficiently cool the recording medium after fixing. Can do.

  According to the sixth aspect of the present invention, the order of the recording media output from the fixing means is the same as that in the case where the present invention is not employed, compared to the case where the present invention is not employed.

  According to the seventh aspect of the present invention, an appropriate cooling time can be ensured by increasing or decreasing the number of conveyance paths as compared with the case where the present invention is not adopted.

  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 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 two-stage cooling devices 52 and 53, 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 or the cooling device 53.

  The sheet 18 discharged from the cooling device 52 or the cooling device 53 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 or the cooling device 53 forms an image on both sides, the paper is reversed by the paper reversing mechanism 54, and along the reverse conveyance path 58 provided below the image processing unit 12. And then returned to the guide unit 20 and sent again to the conveyance path of the image processing unit 12.

  In FIG. 1, the cooling device 52 and the cooling device 53 are configured by two pairs of transport rollers 68.

  As shown in FIG. 2, the cooling devices 52, 53 having a two-stage upper and lower structure are provided with a guide unit 60 between the fixing unit 46. The guide unit 60 includes a movable guide unit 60 </ b> A as a distribution unit that selectively distributes to any one of the cooling devices 52 and 53.

  That is, the guide portion 60 has a bifurcated structure starting from the fixing portion 46, and one end of the movable guide portion 60A is rotatably attached to the bifurcated portion via the shaft 61.

  Here, when the movable guide portion 60A rotates about the shaft 61 in the counterclockwise direction of FIG. 2 and is in the position of the solid line in FIG. 2, the sheet 18 discharged from the fixing portion 46 is sent to the upper cooling portion 52. invite.

  Further, when the movable guide 60A rotates about the shaft 61 in the clockwise direction in FIG. 2 and is in the chain line position in FIG. .

  The upper cooling device 52 includes a belt 66 that is an example of a pair of endless annular members, two rollers 68 that circulate around the pair of belts 66, and a pair of metal disposed in the inner space of the pair of belts 66, respectively. Member 70.

  In addition, the belt should just be a material excellent in heat conductivity, and what is necessary is just to be able to form thin plates, such as a polyimide film, a nickel electroformed film, and a polyethylene film.

  Therefore, when the belts 66 of the cooling device 52 contact each other in a plane and the sheet 18 is fed, the sheet 18 is sandwiched between the belts 66 in contact with the plane and the surface of the sheet 18 is Both the back surface and the back surface 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.

  In the metal member 70, in order to create a flow of wind from the front side to the back side in FIG. 1, a blower (not shown) (usually referred to as “fan”) is provided on the front side or the back side in FIG. ) Is preferably provided.

  Since the lower cooling device 53 has the same structure, the same reference numerals are given and description of the structure is omitted.

  The sheet 18 cooled by the two-stage cooling devices 52 and 53 is guided by a movable guide portion 63A provided in the discharge guide portion 63 having a symmetrical structure with the guide portion 60, via a common conveyance path. It is sent to the tray 56 or the reversing mechanism 54 described above.

  As shown in FIG. 4, the cooling devices 52 and 53 may be configured to have only the two pairs of rollers 68 without the belt 66 and the metal member 70, and may be naturally cooled.

  Further, in this case, in order to equalize the conveying distances of both, the tangential extension line of the contact position of the heating roller 48 and the pressure roller 50 of the fixing unit 46 (see the one-dot chain line in FIG. 4) is used as a boundary vertically. A conveyance path may be formed. This uniform conveyance path length can also be applied to the structures shown in FIGS. 1 and 2 (the cooling devices 52 and 53 in which the belt 66 and the metal member 70 exist).

  Further, as shown in FIG. 5, a three-stage sorting structure may be used, and four or more stages may be used.

  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 fixing unit 46, the paper 18 is sent between the heating roller 48 and the pressure roller 50, and predetermined heat is applied under a predetermined pressure, so that the toner is fixed to the paper 18.

  Here, the fixed sheets 18 are not normally transferred to a sheet on which toner is superimposed even if they are sequentially stacked, but the image forming process is executed at a predetermined speed or more, and a predetermined number of sheets overlap each other. When stacked on the tray 56, pressure is applied before sufficient heat escapes from the paper 18, and the toner is not completely fixed, and may transfer between the overlapping paper.

  In the present embodiment, the cooling devices 52 and 53 having a two-stage upper and lower structure are arranged, and the movable guide portion 60A is provided to guide the paper 18 alternately.

  More specifically, as shown in FIG. 3, when the first sheet 18 is discharged from the fixing unit 46, it is guided to the upper cooling device 52. After that, when the second sheet 18 is subsequently discharged from the fixing unit 46, the movable guide unit 60A is switched and guided to the lower cooling device 53. The first sheet 18 is held in the upper cooling device 52 for the time required to guide the second sheet 18 to the lower cooling device 53.

  When the second sheet 18 is guided to the lower cooling device 53, the first sheet 18 is discharged from the upper cooling device 52, and the third sheet 18 is guided to the upper cooling device 52. .

  The fourth sheet, fifth sheet,..., N-th sheet 18 are alternately guided from the upper stage to the lower stage to the upper stage to.

  The sheets 18 follow the so-called first-in first-out principle at each stage and are discharged in the same order as the order of the sheets 18 sent from the fixing unit 46.

  Further, in each of the cooling devices 52 and 53, since the paper 18 is sandwiched and adhered between the pair of belts 66, the thermal conductivity is better than that of the cooling air.

  Further, a metal member 70 is arranged 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-described 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 having a predetermined radius of curvature or less so as not to cause curling wrinkles (also referred to as curl wrinkles). This circular conveyance is intended to improve the adhesion between the paper 18 and the belt 66.

  Furthermore, in the above embodiment, the cooling devices 52 and 53 having the upper and lower two-stage structures are provided. However, by providing three or more stages, the cooling time can be increased according to the number of stages. In this case, the simplest sorting may be performed by repeatedly feeding the sheets 18 in order to the cooling devices at each stage.

  On the other hand, for example, when a three-stage cooling device is used (see FIG. 5), the cooling capacity is changed or the number of stages to be applied is determined based on the type of paper 18 and the thickness dimension (convertible to paper weight). It may be.

  That is, in Table 1, plain paper and coated paper are listed as the types of paper 18. In addition, there are thin paper, medium thick paper, and thick paper for each type.

  Since plain thin paper is the easiest to cool, the cooling device is not distributed (only one stage is used) and the cooling capacity is the lowest.

  On the other hand, since the coated paper is the hardest to cool, the cooling device is used in all stages (using three stages) and the cooling capacity is the highest.

  The cooling capacity may be changed depending on, for example, the amount and intensity of cooling air blown by a fan or the like.

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. FIG. 10 is a characteristic diagram showing a transition of the leading end position of a sheet when the sheet is alternately distributed to a cooling device having a two-stage upper and lower structure. It is an enlarged view of the cooling device of the natural cooling structure which concerns on a modification. It is an enlarged view of the cooling device of the three-stage distribution structure which concerns on a modification.

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 (fixing means)
48 Heating roller 50 Pressure roller 52, 53 Cooling device 54 Paper reversing mechanism 56 Discharge tray 58 Reverse transport path 60 Guide 60A Movable guide (sorting means)
61 Axis 63 Guide part 63 Movable guide part 66 Belt (cooling means)
68 Roller 70 Metal member (cooling means)

Claims (7)

Fixing means for fixing the developer by heating the recording medium to which the developer has been transferred;
A distribution unit that distributes the recording medium on which the developer is fixed by the fixing unit to a plurality of conveyance paths;
The image forming apparatus, wherein the recording medium distributed to the plurality of conveyance paths by the distribution unit is cooled in a time that remains on the plurality of conveyance paths. Fixing means for fixing the developer by heating the recording medium to which the developer has been transferred;
A distribution unit that distributes the recording medium on which the developer is fixed by the fixing unit to a plurality of conveyance paths;
An image forming apparatus comprising: a cooling unit configured to cool the recording medium on a conveyance path distributed by the distribution unit.   The image forming apparatus according to claim 2, wherein the cooling unit is provided in each of the conveyance paths distributed by the distribution unit.   4. The cooling unit according to claim 2, wherein the cooling unit includes an endless annular member that circulates while being in surface contact with the recording medium, and a cooling member that cools in contact with the endless annular member. Image forming apparatus.   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 claim 2 or 3.   The order of the recording media discharged from the fixing unit is the same order after being sorted into a plurality of transport paths by the sorting unit and cooled. The image forming apparatus according to claim 1.   The image forming apparatus according to any one of claims 1 to 6, wherein the number of use of a plurality of transport paths is determined according to a thickness or a material of the recording medium.

Images