JP2024010975A - image forming system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming system that can prevent the occurrence of tacking while maintaining energy saving/high productivity.

SOLUTION: An image forming system comprises: a conveying unit that conveys a sheet; an image forming unit that has an image carrier carrying toner, and prints a toner image formed through exposure and development processing on the image carrier on the sheet; a fixing unit that fixes the toner image formed on the sheet onto a surface of the sheet through application of heat and pressure using a fixing nip; a cooling unit that is disposed on the downstream side of the fixing unit in a conveyance direction, and cools the sheet; a plurality of sheet mounting units that are disposed branched individually from a conveyance path of the conveying unit as ejection destinations of the sheet in the conveying unit, and have printed sheets mounted thereon; and a control unit that controls the operating state of the cooling unit so that as a conveyance time becomes longer, which is from when the sheet passes through the fixing unit until when the sheet reaches an ejection destination mounting part of the plurality of sheet mounting units, output from the cooling unit becomes smaller.

SELECTED DRAWING: Figure 5

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present disclosure relates to an image forming system.

Conventionally, a latent image is formed on an image bearing member, toner is attached to the latent image to form a toner image, the toner image is transferred to paper and fixed by heating with a fixing device, and the toner image is fixed on the paper. An image forming apparatus is known in which the paper is then conveyed to a paper discharge tray and stacked thereon.

The sheets on which the toner images have been fixed come into contact with other members or rub against each other during transportation, and are finally deposited on the sheet discharge tray. Immediately after being fixed on the paper, the toner is in a high temperature and unstable welded state, and gradually cools and hardens over time.

However, in recent years, the development of image forming apparatuses that can handle high-speed and high-volume processing has progressed, and due to the high temperature after heat fixing, there are cases where paper loaded with toner that is not completely hardened and is in a welded state is deposited on the paper output tray. is increasing.

In such an image forming apparatus, the fused toner loaded on the paper is pressed by the mass of a large amount of paper deposited on top of it, causing the toners to adhere to each other/paper to paper, and to adhere to adjacent paper. This has caused problems such as tacking (toner peeling).

Japanese Patent Application Publication No. 2006-350244 Japanese Patent Application Publication No. 2006-16193 Japanese Patent Application Publication No. 2002-268305

Conventionally, as a countermeasure against the above-mentioned tacking, a method has been adopted in which the toner is quickly cooled and solidified by cooling the paper with air blown by a cooling fan (the air volume is changed depending on the paper conditions) (for example, see Patent Document 1 and Patent Document 2). ).

However, constantly operating the cooling fan at high output in order to reliably prevent tacking causes problems such as increased power consumption and worsened noise. In addition, if the air volume of the cooling fan is increased to blow a large amount of air onto the paper on the conveyance path, there is a problem in that the paper is likely to fold or cause poor conveyance due to frictional resistance between the conveyance path and the paper.

Other countermeasures against tacking include methods such as temporarily stopping the paper in the transport path or lengthening the transport path to wait until the paper cools down, but these methods have the problem of reduced productivity. (For example, see Patent Document 3).

The present invention has been made in view of the above problems, and an object of the present invention is to provide an image forming system that can suppress the occurrence of tacking while maintaining energy saving and high productivity.

The main invention that solves the above-mentioned problems is as follows:
a transport unit that transports paper;
an image forming unit that has an image carrier that carries toner and prints a toner image formed by exposing and developing the image carrier on the paper;
a fixing unit that fixes the toner image formed on the paper onto the paper surface of the paper by applying heat and pressure using a fixing nip;
a cooling unit that is disposed downstream of the fixing unit in the conveying direction and cools the paper;
a plurality of paper stacking units each branching from a transport path of the transporting unit as a discharge destination of the paper in the transporting unit and stacking the printed paper;
The cooling unit is configured such that the longer the conveyance time from when the paper passes through the fixing unit until it reaches the discharge destination stacking unit of the plurality of paper stacking units, the smaller the output of the cooling unit becomes. a control unit that controls the operating state of the
This is an image forming system equipped with

According to the image forming system according to the present invention, it is possible to suppress the occurrence of tacking while maintaining energy saving/high productivity.

A diagram showing the overall configuration of an image forming system according to the first embodiment A diagram showing a configuration example of a post-processing device of an image forming system according to a first embodiment. A diagram showing the configuration of a control system of an image forming system according to the first embodiment A diagram showing an example of a data structure of an air volume setting table referenced by the control unit according to the first embodiment Flowchart showing a cooling fan control procedure by the control unit of the image forming system according to the first embodiment A diagram showing an example of an adjustment amount setting table for adjusting the output of the cooling fan, which is referred to by the control unit according to the second embodiment. A diagram showing a configuration example of a post-processing device of an image forming system according to a third embodiment. A diagram showing an example of an adjustment amount setting table for adjusting the output of the cooling fan, which is referred to by the control unit according to the third embodiment. A diagram showing an example of an adjustment amount setting table for adjusting the output of the cooling fan, which is referred to by the control unit according to the fourth embodiment. A diagram showing an example of an adjustment amount setting table for adjusting the output of the cooling fan, which is referred to by the control unit according to the fifth embodiment. A diagram illustrating another example of an adjustment amount setting table for adjusting the output of the cooling fan, which is referred to by the control unit according to the fifth embodiment. A diagram showing an example of an adjustment amount setting table for adjusting the output of the cooling fan, which is referred to by the control unit according to the sixth embodiment.

Preferred embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. Note that in this specification and the drawings, components having substantially the same functions are designated by the same reference numerals and redundant explanation will be omitted.

(First embodiment)
[Example of configuration of image forming apparatus]
First, the overall configuration of an image forming system (hereinafter referred to as "image forming system U") according to an embodiment of the present invention will be described with reference to FIGS. 1 to 3.

FIG. 1 is a diagram showing the overall configuration of an image forming system U.

The image forming apparatus system U includes an image forming apparatus 1 and a post-processing apparatus 200 connected to a downstream stage of the image forming apparatus 1.

First, the configuration of the image forming apparatus 1 will be explained.

The image forming apparatus 1 forms images on paper using an electrophotographic method, and uses five colors: yellow (Y), magenta (M), cyan (C), black (K), and special color (here, white). This is a tandem-type color image forming device that overlaps colored toners.

The image forming apparatus 1 includes a document transport section 10, a paper storage section 20, an image reading section 30, an image forming section 40, an intermediate transfer unit 50, a secondary transfer section 60, a fixing section 80, and a cooling section. 90 and a control section 100.

The document conveyance unit 10 includes a document feed table 11 on which a document is set, a plurality of rollers 12, a conveyance drum 13, a conveyance guide 14, a document discharge roller 15, and a document discharge tray 16. The originals G set on the original paper feed table 11 are transported one by one to the reading position of the image reading section 30 by a plurality of rollers 12 and a transport drum 13. The conveyance guide 14 and the document discharge roller 15 discharge the document G conveyed by the plurality of rollers 12 and the conveyance drum 13 onto the document discharge tray 16 .

The paper storage section 20 is arranged at the lower part of the main body of the apparatus, and a plurality of paper storage sections 20 are provided depending on the size and type of paper P. This paper P is fed by the paper feed section 21 and sent to the conveyance section 23, and then conveyed by the conveyance section 23 to the secondary transfer section 60, which is a transfer position. Further, a manual feed section 22 is provided near the paper storage section 20. From this manual feed section 22, paper of a size not stored in the paper storage section 20, tag paper with a tag, special paper such as an OHP sheet is sent to the transfer position.

The image reading unit 30 reads the image of the original G transported by the original transport unit 10 or the original placed on the original platen 31, and generates image data. Specifically, the image of the document G is irradiated by the lamp L. The reflected light from the original G is guided to the first mirror unit 32 , the second mirror unit 33 , and the lens unit 34 in this order, and is imaged on the light receiving surface of the image sensor 35 . The image sensor 35 photoelectrically converts the incident light and outputs a predetermined image signal. The output image signal is A/D converted to create image data.

The image reading section 30 also includes an image reading control section 36. The image reading control unit 36 performs processing such as shading correction, dither processing, and compression on the image data created by A/D conversion, and stores the data in the RAM 103 (see FIG. 3) of the control unit 100. Note that the image data is not limited to data output from the image reading section 30, but may be data received from an external device such as a personal computer or another image forming apparatus connected to the image forming apparatus 1.

An image forming section 40 and an intermediate transfer unit 50 are arranged between the image reading section 30 and the paper storage section 20. The image forming section 40 includes five image forming units to form toner images of each color of yellow (Y), magenta (M), cyan (C), black (K), and special color (here, clear toner). It has 40Y, 40M, 40C, 40K, and 40Z.

The first image forming unit 40Y forms a yellow toner image, and the second image forming unit 40M forms a magenta toner image. Further, the third image forming unit 40C forms a cyan toner image, the fourth image forming unit 40K forms a black toner image, and the fifth image forming unit 40Z forms a white toner image. Form. Since these five image forming units 40Y, 40M, 40C, 40K, and 40Z each have the same configuration, the first image forming unit 40Y will be described here.

The first image forming unit 40Y includes a drum-shaped photoreceptor 41, a charging section 42 arranged around the photoreceptor 41, an exposing section 43, a developing section 44, and a cleaning section 45. The photoreceptor 41 is rotated by a drive motor (not shown). The charging unit 42 charges the photoreceptor 41 to uniformly charge the surface of the photoreceptor 41. The exposure unit 43 forms an electrostatic latent image on the photoreceptor 41 by performing an exposure operation on the surface of the photoreceptor 41 based on image data read from the document G or image data transmitted from an external device. Form.

The developing section 44 develops the electrostatic latent image formed on the photoreceptor 41 using toner. The developing section 44 attaches yellow toner to the electrostatic latent image formed on the photoreceptor 41. As a result, a yellow toner image is formed on the surface of the photoreceptor 41.

Note that the developing section 44 of the second image forming unit 40M attaches magenta toner to the photoreceptor 41, and the developing section 44 of the third image forming unit 40C attaches cyan toner to the photoreceptor 41. Then, the developing section 44 of the fourth image forming unit 40K attaches black toner to the photoreceptor 41. Then, the developing section 44 of the fifth image forming unit 40Z attaches white toner to the photoreceptor 41.

The cleaning section 45 removes toner remaining on the surface of the photoreceptor 41.

The intermediate transfer unit 50 includes an intermediate transfer belt 51 and a plurality of rollers around which the intermediate transfer belt 51 is stretched.

Further, a primary transfer roller 52 is provided on the intermediate transfer belt 51 at a position facing the photoreceptor 41 of each image forming unit 40Y, 40M, 40C, 40K, and 40Z. The primary transfer roller 52 transfers the toner adhering to the photoreceptor 41 to the intermediate transfer belt 51 by applying a voltage of opposite polarity to the toner to the intermediate transfer belt 51 .

By rotationally driving the intermediate transfer belt 51, toner images formed by the five image forming units 40Y, 40M, 40C, 40K, and 40Z are sequentially transferred onto the surface of the intermediate transfer belt 51. As a result, yellow, magenta, cyan, black, and special color toner images are superimposed on the surface of the intermediate transfer belt 51 to form a color image.

A secondary transfer section 60 is arranged near the intermediate transfer belt 51 and downstream of the conveyance section 23 in the sheet conveyance direction. The secondary transfer unit 60 brings the paper P sent by the transport unit 23 into contact with the intermediate transfer belt 51 and transfers the toner image formed on the outer peripheral surface of the intermediate transfer belt 51 onto the paper P.

The secondary transfer section 60 has a secondary transfer lower roller 61. The lower secondary transfer roller 61 is in pressure contact with the upper secondary transfer roller 56, which is one of the plurality of rollers (the plurality of rollers around which the intermediate transfer belt 51 is stretched) of the intermediate transfer unit 50. The lower secondary transfer roller 61 and the upper secondary transfer roller 56 constitute a secondary transfer nip portion 62 . The secondary transfer nip portion 62 is a transfer position where the toner image formed on the outer peripheral surface of the intermediate transfer belt 51 is transferred to the paper P.

A fixing section 80 is provided on the paper P discharge side of the secondary transfer section 60 . The fixing unit 80 applies pressure and heat to the paper P to fix the transferred toner image onto the paper P. The fixing unit 80 includes, for example, a pair of fixing members, an upper fixing roller 81 and a lower fixing roller 82. The upper fixing roller 81 and the lower fixing roller 82 are arranged in pressure contact with each other, and a fixing nip portion is formed as a pressure contact portion between the upper fixing roller 81 and the lower fixing roller 82.

A heating section is provided inside the upper fixing roller 81 . The roller portion of the upper fixing roller 81 is warmed by the radiant heat from this heating portion. Then, the heat of the roller portion of the upper fixing roller 81 is transferred to the paper P, so that the toner image on the paper P is thermally fixed.

The paper P is conveyed so that the surface onto which the toner image has been transferred by the secondary transfer section 60 (the surface to be fixed) faces the upper fixing roller 81, and passes through the fixing nip section. Therefore, the paper P passing through the fixing nip is pressurized by the upper fixing roller 81 and the lower fixing roller 82 and heated by the roller portion of the upper fixing roller 81.

A switching gate 24 is arranged downstream of the fixing section 80 in the paper conveyance direction. The switching gate 24 switches the conveyance path of the paper P that has passed through the fixing section 80. That is, the switching gate 24 causes the paper P to advance straight in the single-sided image forming mode. Thereby, the paper P is ejected by the pair of paper ejection rollers 25. On the other hand, the switching gate 24 guides the paper P downward in the double-sided image forming mode. In the case of the double-sided image forming mode, the conveyance section 23 conveys the paper P guided downward by the switching gate 24 to the paper reversal conveyance section 26 . As a result, the paper P is subjected to a front-back reversal process in the paper reversing conveyance section 26, and then sent to the transfer position of the image forming section 40 again via the paper refeeding path 27.

The cooling unit 90 is disposed, for example, on the downstream side of the fixing unit 80 in the conveyance direction along the conveyance path of the conveyance unit 23, and cools the paper P after the image forming process and the fixing process have been performed. Cooling. The cooling unit 90 is configured by, for example, a cooling fan (hereinafter also referred to as "cooling fan 90"). The cooling fan 90 is configured to have a variable air volume (i.e., output) under the control of the control unit 100, for example, by changing the rotational speed of the motor, thereby making the cooling capacity for the paper P variable.

Note that the cooling unit 90 may include a pair of cooling rollers arranged to cool the paper P while it is being conveyed to the conveyance unit 23 instead of/or in addition to the cooling fan. Such a pair of rollers can make the cooling capacity for the paper P variable by adjusting the temperature of the outer circumferential surface (that is, the contact surface with the paper P) or the pressure with which the paper P is held.

A post-processing device 200 (see FIG. 2) is arranged downstream of the paper discharge roller 25 in the conveyance direction. The paper P cooled by the cooling fan 90 is introduced into the post-processing device 200 via the paper ejection roller 25, and is subjected to the post-processing set for the print job in the post-processing device 200. The paper is discharged to one of five paper discharge trays H1, H2, H3, HM, and H20 provided in the processing device 200.

FIG. 2 is a diagram showing a configuration example of the post-processing device 200.

The post-processing device 200 includes a first post-processing unit 210, a second post-processing unit 220, and a third post-processing unit 230. The units 230 are connected in this order along the conveyance direction of the paper P. Then, the post-processing device 200 uses the first to third post-processing units 210, 220, and 230 to perform post-processing on the paper P according to the job settings, and then transfers the paper P to five outputs. The paper is discharged to one of the paper trays H1, H2, H3, HM, and H20 (corresponding to the "paper stacking section" of the present invention).

Note that the paper discharge tray H1 is provided in the first post-processing unit 210, the paper discharge tray H2 and paper discharge tray H20 are provided in the second post-processing unit 220, and the paper discharge tray H3 and paper discharge tray HM are provided in the second post-processing unit 220. It is provided in the third post-processing unit 230. Here, the five paper ejection trays H1, H2, H3, HM, and H20 are arranged separately branching from the transport path as paper P output destinations in the transport unit in the post-processing device 200, and are arranged continuously in the print job. It is configured such that sheets P to be printed on can be stacked thereon.

The post-processing device 200 has a transport unit that configures transport paths indicated by arrows a, b, c, d, e, f, g, h, r, t, u, v, and w in FIG. The image forming apparatus 1 receives the image-formed paper P transported by the transport section 23 of the image forming apparatus 1, and transports the paper P along the transport path indicated by these arrows. Conveyance control of the post-processing device 200 is performed according to a post-processing mode set in advance for the job.

The first post-processing unit 210 includes a punching means 211 and a center folding means 212. The paper P sent from the conveyance section 23 (discharge roller 25) of the image forming apparatus 1 enters the first post-processing unit 210 from the direction of arrow a, and is set in the post-processing mode set in advance for the job. , and are transported to one of the three routes indicated by b, c, and d in FIG.

Route b is a route that guides the paper P to the paper discharge tray H1 without performing post-processing.

Path c is used when the punching means 211 punches a hole in the end of the paper P and sends it to the second post-processing unit 220, or when the paper P is sent as is to the second post-processing unit 220 without being subjected to post-processing. It is a career path.

The path d is a path in which the sheets P sent from the image forming apparatus 1 are subjected to a center-folding process one by one or a plurality of sheets at once by the center-folding means 212, and the sheet P that has been subjected to the center-folding process passes through the path e. and sent to the second post-processing unit 220.

The second post-processing unit 220 includes a stapler 221 and a center folding means 222. The paper P sent from the first post-processing unit 210 is conveyed to one of the three routes indicated by f, g, and h in FIG. 2 so that the post-processing mode is set in advance for the job. .

The path f is a path that guides the paper P to the paper discharge tray H2 without being subjected to post-processing by the second post-processing unit 220.

The path g is a path that guides the paper P to the third post-processing unit 230 without being subjected to post-processing by the second post-processing unit 220.

The path h is a path that guides the sheets P to the stapler 221. The stapler 221 stacks a plurality of sheets P to form a sheet bundle, and performs a binding process using staples at the ends or center line of the sheet bundle. The stack of sheets that has been bound along the center line proceeds along the path indicated by arrow r, is subjected to a center-folding process by the center-folding means 222, and is ejected to the paper ejection tray H20. The bundle of sheets whose ends have been bound is sent along a path indicated by an arrow t, and proceeds to the third post-processing unit 230.

The third post-processing unit 230 includes a bookbinding unit 231 that performs a binding process using glue.

The paper P sent from the second post-processing unit 220 is conveyed to one of the three routes indicated by u, v, and w in FIG. 2 so that the post-processing mode is set in advance for the job.

The path u is a path that guides the paper P to the paper discharge tray H3 without being subjected to post-processing by the third post-processing unit 230.

The path v is a path that guides the paper P to the paper discharge tray HM without being subjected to post-processing by the third post-processing unit 230.

The path w is a path for subjecting the paper P to bookbinding processing. The bookbinding means 231 applies hot-melt glue to the edges of the sheets P using the coating means 232, stacks a predetermined number of these sheets P on the mounting table 233, and presses the ends. The binding process is performed by heating. Then, the bookbinding unit 231 sends out the bound paper P to the paper discharge tray HM.

FIG. 3 is a diagram showing the configuration of the control system of the image forming system U.

The control unit 100 centrally controls each unit of the image forming system U. The control unit 100 includes, for example, a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, and the like. Then, in the control unit 100, the CPU 101 reads out a program corresponding to the processing content from the ROM 102, develops it in the RAM 103, and centrally controls the operation of each block of the image forming system U in cooperation with the developed program.

The control unit 100 controls each unit of the image forming system U (image reading unit 30, image forming unit 40, paper feeding unit 21, fixing unit 80, cooling unit 90, and post-processing unit) described with reference to FIGS. device 200), a storage unit 104 that stores outputted image data, etc., an operation display unit 105 that is a touch panel such as a liquid crystal display (LCD), and a PC (personal computer) Ua that is an external information processing device. It is connected via a system bus 107 to a communication unit 108 and the like that are communicatively connected to the system bus 107 . still. The storage unit 104 also stores an air volume setting table and the like that the control unit 100 refers to when setting the air volume of the cooling unit 90 (cooling fan 90).

The control unit 100 sends and receives various data to and from an external device (for example, a personal computer) Ua connected to a communication network such as a LAN (Local Area Network) or a WAN (Wide Area Network) via the communication unit 108. I do. For example, the control unit 100 receives image data transmitted from an external device Ua, and causes the image forming apparatus 1 to form a toner image on the paper P based on this image data (input image data).

<Detailed configuration of control unit 100>
Next, the detailed configuration of the control unit 100 according to this embodiment will be described with reference to FIGS. 4 and 5.

As described above, the control unit 100 according to the present embodiment has a special feature in the control method of the cooling fan 90 from the viewpoint of suppressing the occurrence of tacking while maintaining energy saving/high productivity.

Specifically, the control unit 100 controls the conveyance time ( The operating state of the cooling fan 90 is controlled such that the longer the transport time after image formation (hereinafter referred to as "transport time after image formation"), the smaller the output (that is, the air volume) of the cooling fan 90 becomes. This is because the longer the transportation time after image formation, the more the toner fixed on the paper P solidifies, and the more tacking becomes less likely to occur when the paper P is placed on the paper ejection tray. That is, during printing, the transportation time after image formation is long, and the toner fixed on the paper P solidifies due to natural cooling until it is placed (that is, deposited) on the paper output tray. Regarding this, the problem of tacking does not occur even if the output (i.e., air volume) of the cooling fan 90 is reduced, and from the viewpoint of energy saving, it is more useful to reduce the output (i.e., air volume) of the cooling fan 90. It is.

The control unit 100 controls the output of the cooling fan 90 based on, for example, the position of the paper P output tray specified from the job settings. That is, the control unit 100 according to the present embodiment estimates the conveyance time after image formation from the position of the destination tray of the paper P, and controls the output of the cooling fan 90.

However, the control unit 100 may specify the post-image-forming transport time using a paper detection sensor (not shown) provided in the fixing unit 80 and the destination tray. In that case, for example, the control unit 100 may control the output of the cooling fan 90 based on the post-image-forming conveyance time detected for the first sheet at the start of the job.

FIG. 4 is a diagram showing an example of the data structure of the air volume setting table. This table is referred to by the control unit 100 of the image forming system 1 when specifying the air volume of the cooling fan. This air volume setting table stores information indicating the air volume of the air cooling fan (the size of the air volume is level 1 < level 2 < level 3; the same applies hereinafter) in association with the output tray of the paper P. do.

The image forming system U according to the present embodiment has five paper ejection trays H1, H2, H3, HM, and H20, and the paper P is ejected to any of the five paper ejection trays H1, H2, H3, HM, and H20. The transportation time after image formation differs depending on whether the image is formed or not. Specifically, the distances of the five paper ejection trays H1, H2, H3, HM, and H20 from the paper inlet of the post-processing device 200 (that is, the distance from the fixing unit 80) are as follows: Tray H2, paper ejection tray H20, paper ejection tray H3, and paper ejection tray HM are further away in this order, and depending on the distance, the transport time after image formation is longer than that of paper ejection tray H1, paper ejection tray H2, and paper ejection tray. H20, paper ejection tray H3, and paper ejection tray HM are longer in this order (here, the conveyance time is described ignoring the time required for post-processing, but more preferably, the time required for post-processing is taken into account (the second See embodiments of )).

Therefore, on the air volume setting table in FIG. 4, when the paper P output destination tray is the paper output tray H1, air volume level 3 is applied, and when the paper P output destination tray is the paper output tray H2, the air volume level 3 is applied. 2 is applied, and when the output tray of paper P is output tray H3, air volume level 1 is applied, and when the output tray of paper P is output tray HM, air volume level 1 is applied. It is configured.

Note that when the paper P output destination tray is the paper output tray H20, air volume level 3 is applied, and when the paper P output destination tray is the paper output tray H2, a higher air volume level is applied. The reason for this is that the paper output tray H20 exists in a closed space inside the post-processing device 200, and due to the influence of the residual heat of the printed paper P (that is, the heat radiation is trapped), the area around the paper output tray H20 is This is because the environment is placed in a situation where the ambient temperature tends to increase. That is, when the paper P is placed (that is, stacked) on the paper output tray H20, the paper P is compared with the other four paper output trays H1, H2, H3, and HM, which are placed exposed to the outside air. Therefore, it will take time for the temperature to drop. When a large amount of paper P is stacked on the destination tray, the weight of the paper P presses the paper P/toner together and sticks to each other, making it easy for tacking to occur.

From this point of view, the control unit 100 according to the present embodiment is configured such that when the paper P output tray is in a closed space, the paper P output tray is exposed to the outside air under the same transportation time after image formation. The operating state of the cooling fan 90 is controlled so that the output of the cooling fan 90 is greater than that under the exposed situation.

Although not specified in the air volume setting table of FIG. 4, the control unit 100 according to the present embodiment increases the output of the cooling fan 90 only when printing on the paper P is double-sided printing. (i.e., air volume level 2 or air volume level 3), and when printing on paper P is one-sided printing, the output of the cooling fan 90 is reduced (i.e., air volume level 1) (see the flowchart in FIG. 5). This is because when the printing on the paper P is one-sided printing, the toner images of the paper P overlapped on the paper ejection tray do not come into contact with each other, so there is no possibility of tacking occurring.

Note that when determining whether or not printing on paper P in a print job is double-sided printing, it is possible to refer to whether double-sided printing is set in the print job, or to determine whether or not double-sided printing is set in the print job. A method may be used in which it is determined whether the coverage of even pages of the image to be printed is equal to or higher than a predetermined reference value (for example, 5%).

FIG. 5 is a flowchart showing a procedure for controlling the cooling fan 90 by the control unit 100. The processing in this flowchart is executed, for example, when a print command is received from a user.

In step S1, the control unit 100 acquires data related to print conditions of a print job for which a print command has been received. Data related to printing conditions include, for example, the print mode indicating either single-sided printing or double-sided printing, the type of paper P (e.g., size and physical properties), the manner of post-processing for paper P, and the discharge destination of paper P. Such as a tray.

Note that among the five paper output trays H1, H2, H3, HM, and H20, the destination tray for paper P is set by the user, but the destination tray is set in the print job. The settings may be automatically set based on the type of post-processing performed and/or the type of paper P (for example, size and physical properties). For example, if the post-processing device 200 is set to perform binding processing (bookbinding processing), the control unit 100 may automatically set the paper discharge tray HM as the paper P discharge destination tray. Further, when the size of the paper P is A4 size, the control unit 100 automatically sets the paper output tray H2 as the output destination tray for the paper P, and when the size of the paper P is B4 size, the control unit 100 automatically sets the paper output tray H2 as the output destination tray for the paper P. The paper output tray H3 may be automatically set as the paper output tray.

In step S2, the control unit 100 determines whether the print mode of the print job is double-sided printing. Then, if the print mode of the print job is double-sided printing (S2: YES), the control unit 100 advances the process to step S3, and if the print mode of the print job is not double-sided printing (S2: NO), the control unit 100 advances to step S5. Proceed with the process.

In step S3, the control unit 100 determines whether the coverage of the image of the even-numbered page to be printed in the print job is equal to or higher than a predetermined reference value (for example, 5%). Then, if the coverage of the even-numbered page image to be printed in the print job is equal to or higher than a predetermined reference value (for example, 5%) (S3: YES), the control unit 100 advances the process to step S4, and If the coverage of the even-numbered page image to be printed is less than a predetermined reference value (for example, 5%) (S3: NO), the process advances to step S5.

This step S3 is a process for determining whether the print job is substantially double-sided printing. In other words, if the coverage of the even-numbered page image to be printed in the print job is less than a predetermined standard value (for example, 5%), the ejected paper is This is because the possibility that the toner images of the sheets P stacked on the tray will come into contact with each other is low, so the possibility that tacking will occur is also low.

In step S4, the control unit 100 determines which of the five paper ejection trays H1, H2, H3, HM, and H20 is set as the ejection destination tray of the paper P based on the data related to the print conditions, and Depending on the destination tray, the process proceeds to step S5, step S6, or step S7. Here, the control unit 100 advances the process to step S5 if the paper P output destination tray is the paper output tray H3 or HM, and if the paper P output destination tray is the paper output tray H2, the control unit 100 advances the process to step S6. If the paper P is discharged to the paper discharge tray H1 or H20, the process advances to step S7.

In step S5, the control unit 100 sets the output of the cooling fan 90 to air volume level 1, and starts operating the cooling fan 90.

In step S6, the control unit 100 sets the output of the cooling fan 90 to air volume level 2, and starts operating the cooling fan 90.

In step S7, the control unit 100 sets the output of the cooling fan 90 to air volume level 3, and starts operating the cooling fan 90.

In step S8, the control unit 100 starts the print job for which the print command has been received.

Through the above-described series of flows, the control unit 100 executes the print job while appropriately controlling the output of the cooling fan 90.

[effect]
As described above, the control unit 100 according to the present embodiment stores information regarding the output tray of the paper P (for example, if the output tray is one of the five output trays H1, H2, H3, HM, and H20) during printing. cooling unit 90 so that the longer it takes for the paper P to reach the output tray after it passes through the fixing unit 80, the lower the output of the cooling unit 90 is. The operating state of the section 90 is controlled (for example, the air volume of the cooling fan 90 is controlled).

Thereby, in the image forming apparatus 1, it is possible to suppress the operation state of the cooling fan 90 to the necessary minimum while suppressing the occurrence of tacking. That is, thereby, the power consumption of the cooling fan 90 can be suppressed, and the generation of noise due to the operation of the cooling fan 90 can also be suppressed. Further, since there is no need for the image forming apparatus 1 to temporarily stop the paper P in the middle of the conveyance path, high productivity can be maintained. Moreover, this also makes it possible to suppress the frequency of occurrence of transport failure accidents that occur when the air volume of the cooling fan 90 is excessively increased.

(Second embodiment)
In the embodiment described above, the control unit 100 determines the output of the cooling fan 90 without considering the post-processing mode in the post-processing device 200. However, the transport time (transport time after image formation) from when the paper P passes through the fixing unit 80 until it reaches the destination tray of the plurality of paper ejection trays H1, H2, H3, HM, and H20 is Even if the destination trays are the same, much depends on the post-processing mode in the post-processing device 200. At this time, as described above, if the conveyance time after image formation becomes longer, the temperature of the paper P decreases due to natural cooling during the conveyance time, so that the risk of tacking is reduced.

From this point of view, the control unit 100 according to the present embodiment adjusts the output of the cooling fan 90 based on the information regarding the position of the output tray of the paper P specified from the job settings and the post-processing mode in the post-processing device 200. (i.e., air volume). The image forming system U according to this embodiment differs from the first embodiment only in the process in which the control unit 100 determines the output of the cooling fan 90. Descriptions of configurations common to the first embodiment will be omitted (hereinafter, the same applies to other embodiments).

FIG. 6 is a diagram showing an example of an adjustment amount setting table for adjusting the output of the cooling fan 90, which is referred to by the control unit 100 according to the present embodiment. The table data in FIG. 6 includes the output adjustment amount (-ΔVs1) of the cooling fan 90 when post-processing by the first post-processing unit 210 (that is, center-folding processing by the center-folding means 212), The output adjustment amount (-ΔVs2) of the cooling fan 90 when post-processing by the processing unit 220 (i.e., binding processing by the stapler 221) is performed, and the post-processing by the third post-processing unit 230 (i.e., the binding unit 231) The output adjustment amount (-ΔVs3) of the cooling fan 90 when the bookbinding process is performed is stored. These output adjustment amounts are applied so as to be subtracted from the output of the air volume level of the cooling fan 90 determined in FIG. 4, for example.

Specifically, when the post-processing process in the post-processing device 200 is included, the control unit 100 according to the present embodiment takes into consideration the lengthening of the transportation time after image formation due to the post-processing process. Adjustment of the output of the cooling fan 90 determined according to the table data of FIG. 6 from the output of the cooling fan 90 determined according to the table data of FIG. 4 (that is, the output determined in steps S5, S6, and S7 of FIG. 5) The value obtained by subtracting the amount is determined as the final output of the cooling fan 90.

As described above, the image forming apparatus 1 according to the present embodiment can adjust the output of the cooling unit 90 in consideration of the post-processing mode in the post-processing device 200, thereby further promoting energy saving. It is useful in that it can be done.

(Third embodiment)
FIG. 7 is a diagram showing a configuration example of the post-processing device 200 of the image forming system U according to the present embodiment. The image forming system U according to this embodiment includes temperature sensors S-H1, S-H2, S-H3, S-HM, and S-H1, S-H2, S-H3, S-HM and - Contains H20.

As mentioned above, whether or not tacking occurs on the paper P when placed on the output tray depends on whether the toner on the paper P solidifies before other paper P is stacked on top of the paper P. It depends on the extent to which it is done. This is because when a large amount of paper P is stacked on the destination tray, the weight of the paper P presses the paper P/toner together and sticks to each other, making it easy for tacking to occur.

That is, the degree to which tacking occurs in the paper P also depends on the ambient ambient temperature of the destination tray, which affects the rate at which the temperature of the paper P decreases. The ambient temperature around the paper output tray may increase due to the situation where the paper output tray is in a closed space, the situation where the outside air temperature is high, the type of paper P, and the print settings. Examples include a situation where the temperature of the printed paper P itself is high (that is, the surrounding atmosphere temperature is high due to the paper P accumulated on the paper ejection tray).

From this point of view, the control unit 100 according to the present embodiment, in addition to the information regarding the position of the paper P output destination tray specified from the job settings, further provides information regarding the ambient ambient temperature of the detected paper P output destination tray. Based on this, the output of the cooling fan 90 is controlled. Then, the control unit 100 controls the output of the cooling fan 90 such that the higher the atmospheric temperature around the destination tray, the greater the output of the cooling fan 90.

FIG. 8 is a diagram showing an example of an adjustment amount setting table for adjusting the output of the cooling fan 90, which is referred to by the control unit 100 according to the present embodiment. The table data in Figure 8 includes the output adjustment amount (no adjustment amount) when the ambient ambient temperature of the paper output tray (here, the output tray) is below the reference temperature, the output adjustment amount (no adjustment amount), and the output adjustment amount when the ambient ambient temperature of the paper output tray (here, the output tray) Output adjustment amount (+ΔVt) when the ambient ambient temperature is between the reference temperature or more and less than the reference temperature + 3°C, and the output adjustment amount (+ΔVt) when the ambient ambient temperature of the paper output tray (here, the destination tray) is the reference temperature + 3°C or more. The output adjustment amount (+2ΔVt) is stored.

Note that this reference temperature is set, for example, to about the outside temperature (for example, 25° C.) when the image forming system U is normally used. That is, when the ambient ambient temperature of the destination tray is higher than the reference temperature, the control unit 100 performs cooling in accordance with the table data of FIG. Output adjustment is performed to increase the output of the fan 90. As a result, the output of the cooling unit can be adjusted as necessary to provide an output suitable for suppressing the occurrence of tacking while considering energy saving.

Specifically, the control unit 100 according to the present embodiment, for example, after the processing of steps S5, S6, and S7 in FIG. -In H20, the detection signal of the temperature sensor that detects the ambient ambient temperature of the destination tray specified from the job settings is acquired, and the ambient ambient temperature of the destination tray is specified. Then, the control unit 100 adjusts the output of the cooling fan 90 determined based on the ambient ambient temperature of the discharge destination tray and the table data of FIG. 8 from the output of the cooling fan 90 determined according to the table data of FIG. The value obtained by adding the amount is determined as the final output of the cooling fan 90, and after the operation of the cooling fan 90 is started, printing is executed (step S8).

As described above, the image forming apparatus 1 according to the present embodiment can adjust the output of the cooling fan 90 in consideration of the delay in the temperature drop of the paper P on the destination tray. This is useful in that it is possible to reliably save energy while suppressing the occurrence of tacking.

(Fourth embodiment)
According to the findings of the present inventors, when the paper surface of the paper P is smooth, the contact area between the paper sheets/toner particles on the destination tray increases, and tacking is likely to occur. In other words, when the smoothness of the paper P is low, the adhesion between papers/toners when stacking papers is low, and heat is easily dissipated. That is, from the viewpoint of reliably suppressing tacking while suppressing the output of the cooling fan 90, it is preferable to consider the smoothness of the paper P.

From this point of view, the control unit 100 according to the present embodiment performs cooling based on the physical properties related to the smoothness of the paper P in addition to the information related to the position of the output tray of the paper P specified from the job settings. Controls the output of the fan 90. Then, the control unit 100 controls the output of the cooling fan 90 such that the higher the smoothness of the paper P, the greater the output of the cooling fan 90.

The physical properties related to the smoothness of the paper P can be determined by, for example, the detection results of a media sensor (not shown) that detects the physical properties related to the smoothness of the paper P, which is provided in the transport path of the transport unit 23 of the image forming apparatus 1. It is preferable to use In addition to physical properties related to the smoothness of the paper P, the smoothness of the paper P can be indirectly recognized, such as the density of the paper P and the air permeability of the paper P, in addition to the smoothness of the paper P itself. The detection results may be used.

On the other hand, the physical properties related to the smoothness of the paper P may be specified from information related to printing conditions set in a print job. In that case, for example, information related to the type of paper P set in the print job may be used, or the user himself/herself may be configured to input physical properties related to the smoothness of the paper P.

FIG. 9 is a diagram illustrating an example of an adjustment amount setting table for adjusting the output of the cooling fan 90, which is referred to by the control unit 100 according to the present embodiment. The table data in FIG. 9 includes the amount of output adjustment (no adjustment amount) when the smoothness of paper P corresponds to a predetermined medium level, and the amount of output adjustment when the smoothness of paper P corresponds to a predetermined high smoothness state. The output adjustment amount (+ΔVu) and the output adjustment amount (−ΔVu) when the smoothness of the paper P corresponds to a predetermined low smoothness state are stored.

That is, the control unit 100 according to the present embodiment takes into consideration that when the paper surface of the paper P is smooth, the contact area between the paper sheets and the toners increases on the discharge destination tray, and tacking is likely to occur. , adjust the output of the cooling fan 90 in the direction of increasing the output, and check that if the paper surface of the paper P is rough, the contact area between the paper sheets/toner particles on the destination tray is small and tacking is less likely to occur. Taking this into account, the output of the cooling fan 90 is adjusted in the direction of decreasing it. As a result, the output of the cooling unit 90 can be adjusted as necessary while considering energy saving so that the output is suitable for suppressing the occurrence of tacking.

As described above, the image forming apparatus 1 according to the present embodiment can adjust the output of the cooling fan 90 in consideration of the smoothness of the paper P, so that it is possible to more reliably save energy while , is useful in that it can suppress the occurrence of tacking.

(Fifth embodiment)
According to the findings of the present inventors, when a large amount of paper P is stacked on the destination tray, the weight of the paper P presses the papers/toner together and causes them to stick together, which tends to cause tacking. That is, from the viewpoint of reliably suppressing tacking while suppressing the output of the cooling fan 90, it is preferable to consider the weight of the sheets P loaded on the destination tray during the print job.

From this point of view, the control unit 100 according to the present embodiment, in addition to the information regarding the position of the output tray of the paper P specified from the job settings, also determines the position of the paper stacked on the output tray during the print job. The output of the cooling fan 90 is controlled based on the total number of sheets loaded or the total weight of the sheets P loaded.

FIG. 10 is a diagram showing an example of an adjustment amount setting table for adjusting the output of the cooling fan 90, which is referred to by the control unit 100 according to the present embodiment. The table data in FIG. 10 stores the output adjustment amount (+ΔVk) when the total number of sheets P loaded on the output tray during a print job is equal to or greater than a predetermined threshold (here, 1000 sheets). has been done. Note that the total number of sheets P to be loaded on the destination tray can be determined from the number of sheets P scheduled to be printed in the print job.

FIG. 11 is a diagram illustrating another example of an adjustment amount setting table for adjusting the output of the cooling fan 90, which is referred to by the control unit 100 according to the present embodiment. The table data in FIG. 11 stores the output adjustment amount (+ΔVm) when the total weight of the paper P loaded on the destination tray during a print job is equal to or greater than a predetermined threshold (here, 1000 g). ing. Note that the total weight of the sheets P loaded on the destination tray during a print job can be calculated from the scheduled number of sheets P to be printed in the print job and the type of the sheets P.

That is, the control unit 100 according to the present embodiment controls the control unit 100 when the total number of sheets P loaded on the output tray is equal to or more than a threshold value (here, 1000 sheets), or when the total number of sheets P loaded on the output tray is If the total loaded weight is equal to or greater than a predetermined threshold value (here, 1000 g), the output of the cooling fan 90 is adjusted to increase in order to reliably suppress tacking.

As a result, the output of the cooling fan 90 can be adjusted as necessary to provide an output suitable for suppressing the occurrence of tacking while considering energy saving.

(Sixth embodiment)
According to the findings of the present inventors, when the temperature of the external environment of the image forming apparatus 1 is high, it is difficult for the temperature of the paper P to drop on the destination tray, so tacking is likely to occur.

From this point of view, the control unit 100 according to the present embodiment includes a temperature sensor (not shown) that measures the temperature of the external environment, in addition to information regarding the position of the output tray of the paper P specified from the job settings. ), the output of the cooling fan 90 is controlled based on the temperature information indicated by.

FIG. 12 is a diagram showing an example of an adjustment amount setting table for adjusting the output of the cooling fan 90, which is referred to by the control unit 100 according to the present embodiment. The table data in FIG. 12 stores an output adjustment amount (+ΔVo) when the temperature of the external environment is equal to or higher than a threshold value (here, 25° C.). That is, the control unit 100 according to the present embodiment adjusts the output of the cooling fan 90 to increase the output when the temperature of the external environment is high.

As a result, the output of the cooling unit 90 can be adjusted as necessary while considering energy saving so that the output is suitable for suppressing the occurrence of tacking.

Although specific examples of the present invention have been described in detail above, these are merely illustrative and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes to the specific examples illustrated above.

According to the image forming system according to the present invention, it is possible to suppress the occurrence of tacking while maintaining energy saving/high productivity.

U Image forming system 1 Image forming apparatus 10 Original transport section 20 Paper storage section 30 Image reading section 40 Image forming section 50 Intermediate transfer unit 60 Secondary transfer section 80 Fixing section 90 Cooling section (cooling fan)
100 Control unit 200 Post-processing device H1, H2, H3, HM, H20 Paper output tray (paper stacking unit)
S-H1, S-H2, S-H3, S-HM, S-H20 Temperature sensor

Claims (13)

a transport unit that transports paper;
an image forming section that has an image carrier that carries toner and prints a toner image formed by exposing and developing the image carrier on the paper;
a fixing unit that fixes the toner image formed on the paper onto the paper surface of the paper by applying heat and pressure using a fixing nip;
a cooling unit that is disposed downstream of the fixing unit in the conveying direction and cools the paper;
a plurality of paper stacking units each branching from a transport path of the transporting unit as a discharge destination of the paper in the transporting unit and stacking the printed paper;
The cooling unit is configured such that the longer the conveyance time from when the paper passes through the fixing unit until it reaches the discharge destination stacking unit of the plurality of paper stacking units, the smaller the output of the cooling unit becomes. a control unit that controls the operating state of the
An image forming system equipped with The control unit controls the output of the cooling unit based on the position of the destination loading unit specified from job settings.
The image forming system according to claim 1. The apparatus further includes a post-processing device disposed on the downstream side of the fixing unit in the conveyance path, which performs post-processing on the paper according to job settings and then discharges the paper to the discharge destination stacking unit. ,
The control unit controls the output of the cooling unit based on the aspect of the post-processing specified from the job settings.
The image forming system according to claim 1. The control unit is configured to control a situation in which, under the same transport time, the discharge destination stacking portion of the paper is more exposed to the outside air when the paper discharge destination stacking portion is located in a closed space. controlling the output of the cooling unit so that the output of the cooling unit is greater than when the cooling unit is located below;
The image forming system according to claim 1. including a plurality of temperature sensors that detect ambient ambient temperatures of each of the plurality of paper stacking units;
The control unit controls the output of the cooling unit based on the detected ambient temperature of the paper discharge destination stacking unit.
The image forming system according to claim 1. Further comprising a media sensor that detects a physical property related to smoothness of the paper in the transport path of the transport unit,
The control unit controls an output of the cooling unit based on a physical property related to the smoothness of the paper detected by the media sensor.
The image forming system according to claim 1. It further includes a reception section that accepts settings of printing conditions based on user operation input,
The control unit controls the output of the cooling unit based on physical properties of the paper specified from the set printing conditions.
The image forming system according to claim 1. The control unit is configured such that under the same transport time, the output of the cooling unit is greater when printing is performed on both sides of the paper than when printing is performed on only one side of the paper. controlling the output of the cooling unit so that
The image forming system according to claim 1. The control unit specifies the total number of sheets to be loaded on the output destination stacking unit during the print job based on the content of the print job, and under the same transport time, the total number of sheets is controlling the output of the cooling unit so that the output of the cooling unit is greater when the number of stacked sheets is greater than or equal to a predetermined threshold than when the total number of stacked sheets is less than the predetermined threshold;
The image forming system according to claim 1. The control unit calculates the total loaded weight of the sheets loaded on the output destination stacking unit during the print job based on the content of the print job, and under the same conveyance time condition, the total weight of the sheets is calculated based on the content of the print job. controlling the output of the cooling unit so that the output of the cooling unit is greater when the loaded weight is equal to or higher than a predetermined threshold than when the total loaded weight is less than the predetermined threshold;
The image forming system according to claim 1. comprising a temperature sensor that detects the temperature of an external environment in which the image forming system is installed;
The control unit controls the output of the cooling unit based on the detected temperature of the external environment.
The image forming system according to claim 1. The control unit calculates the coverage of the image to be printed set in the print job, and under the condition that the conveyance time is the same, the coverage is greater than the predetermined threshold value. controlling the output of the cooling unit so that the output of the cooling unit is greater than when the output is less than a threshold;
The image forming system according to claim 1. The cooling unit is a fan disposed to cool the paper while the paper is being transported to the transport unit.
The image forming system according to claim 1.

Images