JP2012047770A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of surely heating and fixing an image on a paper having a large heat quantity necessary for heating and fixing, without decreasing productivity for printing processing for the paper.SOLUTION: In the image forming apparatus 1, when a target paper is fed from an A tray 310a to an F tray 110f, to perform one-side printing processing, a tandem system management part heats and fixes the target paper by a first fixing part 122, then, conveys the target paper to a second image forming unit 200 and heats and fixes the target paper by a second fixing part 222.

Description

  The present invention relates to an image forming apparatus.

2. Description of the Related Art Conventionally, image forming apparatuses such as printers and copiers that perform printing processing on one side or both sides of a sheet are known.
The image forming apparatus includes not only a single-sided printing process or a double-sided printing process (hereinafter referred to as a single-sided image forming apparatus) but also a configuration that can perform the printing process as an image forming unit. Some have a tandem configuration in which a plurality of units are connected (hereinafter, an image forming apparatus having a tandem configuration).

  As an example of the image forming apparatus having the tandem configuration, the print processing speed when the print processing is performed in the tandem configuration state and the print processing when the print processing is performed using one image forming unit included in the tandem configuration. It is known that the print processing speed can be switched by setting the speed (see Patent Document 1).

  By the way, the fixing unit provided in a single image forming apparatus or an image forming apparatus having a tandem configuration must add a larger amount of heat than that of plain paper or the like when heating and fixing, when the amount of paper is large compared to plain paper such as cardboard. In this case, it is impossible to reliably heat and fix the image on the paper.

  Therefore, for example, the conveyance speed of the paper and the speed of the fixing roller can be sequentially switched, and when performing heat fixing of paper made of special paper such as thick paper, the above-mentioned conveyance speed and fixing speed are reduced to There is a single image forming apparatus that reliably heats and fixes an image (see Patent Document 2).

JP-A-8-50429 JP-A-2-53085

  However, the image forming apparatus described in Patent Document 2 can reliably heat and fix an image even on a sheet of paper having a large amount of heat necessary for heat fixing such as cardboard, while reducing the sheet conveyance speed and the fixing roller speed. Therefore, there has been a problem that productivity for the printing process of the paper is lowered.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus capable of reliably heat-fixing an image on a sheet without deteriorating productivity with respect to a printing process for a sheet having a large amount of heat necessary for heat-fixing.

  In order to solve the above problems, an invention according to claim 1 is an image forming apparatus in which a plurality of image forming units are connected in series, and each of the plurality of image forming units has a predetermined fixing heat quantity. Is formed on one of the plurality of image forming units, and an image is formed by one of the plurality of image forming units. After fixing the image formed on the sheet by the fixing unit of the unit, the sheet is transported to a subsequent image forming unit connected to the subsequent stage rather than the one image forming unit, and the subsequent image forming is performed. The image forming apparatus includes a control unit that performs control to execute heat fixing by a fixing unit included in the unit.

  Therefore, the present invention can provide an image forming apparatus that can reliably heat-fix an image on a sheet without deteriorating the productivity with respect to the printing process of the sheet having a large amount of heat necessary for heat-fixing.

1 is a diagram illustrating a schematic configuration of an image forming apparatus according to the present invention. FIG. 2 is a diagram schematically showing an internal structure of a first image forming unit, a second image forming unit, and a paper feeding unit provided in the image forming apparatus of FIG. 1. FIG. 3 is a diagram schematically illustrating a first image forming unit provided in the first image forming unit of FIG. 2 and a second image forming unit provided in the second image forming unit. 1 is a block diagram of an image forming apparatus according to the present invention. FIG. 6 is a diagram illustrating a path followed by a target sheet when single-sided printing processing is performed on the target sheet fed from a G tray to an I tray. FIG. 6 is a diagram illustrating a path followed by a target sheet when a single-sided printing process is performed on a target sheet that is fed from an A tray to an F tray and whose haze amount is less than a predetermined value. The path followed by the target sheet when performing single-sided printing processing on the target sheet fed from the A tray to the F tray and having a glazing amount of a predetermined value or more, or the path followed by the target sheet when performing double-sided printing processing on the target sheet FIG. When single-sided printing processing is performed on the target paper with the fixing paper passing speed and the fixing temperature set in the first image forming unit 100 and the second image forming unit 200 according to the amount of the target paper fed from each tray. FIG. 6 is a diagram illustrating a case where a double-sided printing process is performed. It is a figure which shows the standard screen displayed on a display operation part. FIG. 10 is a diagram illustrating a tray amount setting screen displayed on the display operation unit when a user sets the amount of paper stored in each tray. 6 is a flowchart for explaining print processing executed by the image forming apparatus according to the present invention. 6 is a flowchart for explaining print processing executed by the image forming apparatus according to the present invention. 6 is a flowchart for explaining print processing executed by the image forming apparatus according to the present invention.

  Hereinafter, the image forming apparatus according to the present embodiment will be described with reference to FIGS.

As shown in FIGS. 1 and 2, the image forming apparatus 1 according to the present embodiment includes a paper feeding unit 300, a first image forming unit 100 (one image forming unit), and a second image forming unit 200 (following stage). An image forming unit) and a post-processing unit 400 are arranged in a tandem configuration in series.
The image forming apparatus 1 applies the first image forming unit 100 and the second image forming unit 100 to the sheet fed from the sheet feeding unit 300 or the sheet feeding tray provided in the first image forming unit 100 or the second image forming unit 200. The image forming unit 200 performs printing processing, the post-processing unit 400 performs predetermined post-processing, and outputs (discharges) paper. Here, it is assumed that the first image forming unit 100 and the second image forming unit 200 each execute a printing process on one side of the paper. That is, when executing printing processing on both sides of a sheet, the first image forming unit 100 executes printing processing on one side of the sheet, and the second image forming unit 200 executes printing processing on the opposite side of the sheet. And

As shown in FIG. 2, the paper feed unit 300 includes a paper feed unit tray 310 (first paper feed unit) and a transport path T1.
The sheet feeding unit tray 310 includes a plurality of trays (A tray 310a to C tray 310c), and stores sheets identified on the basis of the amount, size, etc., in each tray for each preset type. Then, the paper stored in the paper supply unit tray 310 is supplied to the first image forming unit 100 via the transport path T1 by the transport roller.

  As shown in FIG. 2, the first image forming unit 100 includes a first paper feed tray 110 (first paper feed unit), a first print processing unit 120, transport path switching units 130 and 131, and ADF (Auto (Document Feeder) 140, scanner 150, display operation unit 160 (notification unit), and conveyance paths T2, T3, T4, and T5.

  The first paper feed tray 110 includes a plurality of trays (D tray 110d to F tray 110f), and accommodates the paper identified based on the amount, size, etc., in each tray for each type set by the user. The paper stored in the first paper feed tray 110 is transported by the transport roller to the transport path T3 via the transport path T2.

  The first print processing unit 120 forms an electrophotographic image on a sheet, and heat-fixes the formed image to perform a printing process. The first print processing unit 120 includes a first image forming unit 121 including a photosensitive drum, a laser unit, and the like, a first fixing unit 122 including a fixing roller (a heating roller and a pressure roller), and the like. including.

  As shown in FIG. 3, the first image forming unit 121 includes a toner image generating unit 1211, an intermediate transfer belt 1212, a registration roller 1213, a guide plate 1214, and a secondary transfer belt 1215. The

The toner image generation unit 1211 generates an electrostatic latent image composed of each color of C (cyan), M (magenta), Y (yellow), and K (black) based on the input image data. To form on the photosensitive drum provided for each color. The toner image generation unit 1211 forms a toner image from the electrostatic latent image on the photosensitive drum by a developing device or the like.
Further, the toner image generation unit 1211 can switch between a state in which the toner image generation unit 1211 is in close contact with the intermediate transfer belt 1212 and a state in which the toner image generation unit 1211 is separated from the intermediate transfer belt 1212 by applying a driving force from a motor or the like (not shown). Of course, it is possible to provide a configuration that can switch between a state of being in close contact with the toner image generation unit 1211 and a state of being separated from the intermediate transfer belt 1212 side.

The intermediate transfer belt 1212 is configured to be rotatable in the direction of the arrow in FIG. The intermediate transfer belt 1212 rotates while being in close contact with the toner image generation unit 1211 (photosensitive drum of each color), thereby intermediate transfer of the toner image formed by the toner image generation unit 1211. The intermediate transfer belt 1212, together with the secondary transfer belt 1215, transfers a toner image onto a sheet, and carries the sheet toward the first fixing unit 122.
The guide plate 1214 guides the sheet fed from the sheet feeding unit 300 or the first sheet feeding tray 110 so as to be conveyed toward the registration roller 1213 or the intermediate transfer belt 1212. The registration roller 1213 aligns the leading edge of the sheet conveyed by the guide plate 1214. Then, the registration roller 1213 carries the sheet toward the intermediate transfer belt 1212 at a timing when the intermediate transfer belt 1212 transfers the toner image onto the sheet. The secondary transfer belt 1215 presses the intermediate transfer belt 1212 to transfer the toner image on the intermediate transfer belt 1212 to a sheet.

  The first fixing unit 122 includes a plurality of fixing rollers that rotate in the forward direction with respect to the sheet conveyance direction and a fixing belt that winds the fixing rollers. The first fixing unit 122 heats and fixes the toner image on the sheet by heating / pressing the fixing surface of the sheet at a fixing temperature and a fixing sheet passing speed set by a tandem system management unit 190 described later. Here, the fixing temperature of the first image forming unit 100 is a temperature at which the first fixing unit 122 heats the paper, and the fixing paper passing speed of the first image forming unit 100 is when passing through the first fixing unit 122. This is the sheet conveyance speed. That is, the amount of heat (hereinafter referred to as fixing heat amount) applied to the sheet by the first fixing unit 122 is determined according to the fixing sheet passing speed (and fixing temperature). That is, the amount of fixing heat of the first fixing unit 122 increases as the fixing temperature is constant and the fixing sheet passing speed is slow, because the time for the first fixing unit 122 to heat and fix the sheet becomes longer. The faster the speed, the shorter the time for the first fixing unit 122 to heat and fix the paper, and the smaller the speed. The fixing temperature / fixing sheet passing speed of the second image forming unit 200 described later is the temperature at which the second fixing unit 222 heats the sheet / the conveyance speed of the sheet when passing through the second fixing unit 122.

The conveyance path switching unit 130 is either a sheet that is carried into the conveyance path switching unit 130 via the conveyance path T1 or a sheet that is carried into the conveyance path switching unit 130 via the conveyance path T2. The transport path is switched so that the sheet of paper is transported to the transport path T3.
The transport path switching unit 131 transports the paper carried into the transport path switching unit 131 via the transport path T3 to the transport path T5 via the transport path T4 or without passing through the transport path T4. Whether to transport to the transport path T5 is switched. Here, when the sheet passes through the conveyance path T4, the sheet is conveyed to the conveyance path T5 in a state where the front surface and the back surface of the sheet are turned upside down.

The ADF 140 automatically conveys the originals stacked on the original placement tray to the scanner 150 in order from the top.
The scanner 150 performs a reading process of the document conveyed by the ADF 140. Specifically, the scanner 150 scans an original with light emitted from a light source, forms an image of reflected light with a CCD (Charge Coupled Device), and performs photoelectric conversion. Then, the scanner 150 acquires a document image from a document read by photoelectric conversion.

  The display operation unit 160 includes an LCD (Liquid Crystal Display), a touch panel provided so as to cover the LCD, an operation key group such as various operation keys and operation buttons, and the like. The display operation unit 160 displays various operation screens and various processing results on the LCD according to instructions from the tandem system management unit 190 described later. Further, when the user operates the touch panel or the operation key group, the display operation unit 160 outputs various operation signals corresponding to the operation content to the tandem system management unit 190.

  As shown in FIG. 2, the second image forming unit 200 includes a second paper feed tray 210 (second paper feed unit), a second print processing unit 220, transport path switching units 230 and 231 and a transport path T6. , T7, T8, and T9.

  The second paper feed tray 210 includes a plurality of trays (G tray 210g to I tray 210i), and accommodates the paper identified based on the amount, size, etc., in each tray for each type set by the user. The paper stored in the second paper feed tray 210 is transported from the transport path T6 to the transport path T7 by the transport rollers.

  The second print processing unit 220 forms an electrophotographic image on a sheet, and heat-fixes the formed image to perform a printing process. The second print processing unit 220 includes a second image forming unit 221 configured with a photosensitive drum, a laser unit, and the like, and a second fixing unit 222 configured with a fixing roller and the like.

  As shown in FIG. 3, the second image forming unit 221 includes a toner image generating unit 2211, an intermediate transfer belt 2212, a registration roller 2213, a guide plate 2214, and a secondary transfer belt 2215. The

The toner image generation unit 2211 forms an electrostatic latent image composed of each color of C, M, Y, and K on a photosensitive drum provided for each color by a charging device or an exposure device based on the input image data. To do. The toner image generation unit 2211 forms a toner image from the electrostatic latent image on the photosensitive drum using a developing device or the like.
Further, the toner image generation unit 2211 can switch between a state in which the toner image generation unit 2211 is in close contact with the intermediate transfer belt 2212 and a state in which the toner image generation unit 2211 is separated from the intermediate transfer belt 2212 by a driving force applied from a motor or the like (not shown). Of course, it is possible to provide a structure that can switch between a state of being in close contact with the toner image generation unit 2211 and a state of being separated from the intermediate transfer belt 2212.

The intermediate transfer belt 2212 is configured to be rotatable in the direction of the arrow in FIG. 3, and the intermediate transfer belt 2212 rotates while being in close contact with the toner image generation unit 2211, thereby forming the toner image generation unit 2211. The toner image to be transferred is intermediately transferred to the paper. The intermediate transfer belt 2212, together with the secondary transfer belt 2215, transfers a toner image onto a sheet and carries the sheet toward the fixing unit 222.
The guide plate 2214 guides the paper carried from the first image forming unit 100 and the paper fed from the second paper feed tray 210 to be conveyed toward the registration roller 2213 and the intermediate transfer belt 2212. The registration roller 2213 aligns the leading edge of the paper conveyed by the guide plate 2214. Then, the registration roller 2213 carries the sheet toward the intermediate transfer belt 2212 at a timing when the intermediate transfer belt 2212 transfers the toner image onto the sheet. The secondary transfer belt 2215 presses the intermediate transfer belt 2212 to transfer the toner image on the intermediate transfer belt 2212 to a sheet.

  The second fixing unit 222 includes a plurality of fixing rollers that rotate in the forward direction with respect to the sheet conveyance direction and a fixing belt that winds the fixing rollers. The second fixing unit 222 heats and fixes the toner image on the paper by heating / pressing the fixing surface of the paper at a fixing temperature and a fixing paper passing speed set by a tandem system management unit 190 described later.

The conveyance path switching unit 230 is either a sheet that is carried into the conveyance path switching unit 230 via the conveyance path T5 or a sheet that is carried into the conveyance path switching unit 230 via the conveyance path T6. The transport path is switched so that the sheet is transported to the transport path T7 or T8.
Whether the transport path switching unit 231 transports the paper carried into the transport path switching unit 231 via the transport path T7 to the transport path T9 via the transport path T8 with the front and back surfaces of the paper reversed. Then, whether to transport to the transport path T9 without passing through the transport path T8 is switched.

  The post-processing unit 400 performs predetermined post-processing on the paper that is carried in via the transport path T9. Examples of post-processing performed by the post-processing unit 400 include sort processing, cutting processing, punching processing, and stapling processing. One or a plurality of the post-processing units 400 are arranged in series according to the processing content desired by the user. The paper that has been post-processed by the post-processing unit 400 is discharged via the paper discharge trays 411 and 412 provided in the post-processing unit 400.

  Next, the functional configuration of the image forming apparatus 1 will be described with reference to the block diagram shown in FIG.

  As shown in FIG. 4, the image forming apparatus 1 includes a paper feeding unit 300, a first image forming unit 100, a second image forming unit 200, and a post-processing unit 400. The units from the first image forming unit 100 to the post-processing unit 400 are connected so that data can be transmitted and received by serial communication or the like.

  The first image forming unit 100 includes an ADF control unit 141, a scanner control unit 151, a first print processing unit 120, a first paper transport unit 132, a first paper feed tray control unit 111, and a first control unit. 170, a first state management unit 171, a paper feed unit control unit 172, a first image processing unit 180, and a tandem system management unit 190.

The ADF control unit 141 performs drive control of the ADF 140 when a document is placed on the ADF 140. The scanner control unit 151 performs reading control of a document image by the scanner 150. The first paper feed tray control unit 111 performs control to feed paper from one of the D trays 110d to 110f provided in the first paper feed tray 110.
The first paper transport unit 132 is configured to feed paper fed from the first paper feed tray 110 via the transport path switching unit 130 (paper passing through the transport path T2) or paper carried from the paper feed unit 300 (conveyance). Control is performed to transport any one of the sheets passing through the path T1 to the transport path T3. In addition, the first paper transport unit 132 passes the transported paper via the transport path switching unit 131 to the transport path switching unit 131 via the transport path T3 and the front and back surfaces of the paper via the transport path T4. Is controlled so as to switch between transporting to the transport path T5 and transporting to the transport path T5 without passing through the transport path T4.

  The first control unit 170 follows the instruction signal transmitted from the tandem system management unit 190, the ADF control unit 141, the scanner control unit 151, the first paper feed tray control unit 111, the first print processing unit 120, the first paper transport The drive of the unit 132, etc. is controlled.

  The first state management unit 171 manages (controls) the entire operation of the first image forming unit 100 based on an instruction from the tandem system management unit 190. Specifically, the first state management unit 171 transmits an instruction signal to the first image processing unit 180 to perform control for generating an image for printing.

  The paper feed unit control unit 172 sends an instruction signal to the paper feed unit 300 and feeds paper from one of the A trays 310 a to 310 c of the paper feed unit 300 to the first image forming unit 100. Let

  The first image processing unit 180 performs various image processing according to the instruction signal transmitted from the first state management unit 171 and generates an image for printing. For example, the first image processing unit 180 performs RIP processing or the like on a print job transmitted from a PC (Personal Computer) connected to the first image forming unit 100 via a LAN (Local Area Network) or the like. Generate an image for printing. Further, the first image processing unit 180 generates an image for printing based on the original image read by the scanner 150. The image generated by the first image processing unit 180 is formed on a sheet by the first image forming unit 121.

The tandem system management unit 190 includes a CPU (Central Processing Unit), a RAM (Random Access Memory), and a ROM (Read Only Memory). The tandem system management unit 190 reads various programs stored in the ROM and develops them in the RAM. Then, the tandem system management unit 190 controls the overall operation of the first image forming unit 100 by executing the developed various programs and outputting various instruction signals to the first state management unit 171. The tandem system management unit 190 also controls the operation of the second image forming unit 200 via the second state management unit 271 by outputting an instruction signal to the second state management unit 271 described later by serial communication. That is, the tandem system management unit 190 functions as a control unit.
Specifically, when the tandem system management unit 190 acquires a print job or receives a print instruction from the user via the display operation unit 160, the tandem system management unit 190 forms the first image based on the print job or the print instruction. It is determined which unit of the unit 100 and the second image forming unit 200 is to execute the printing process. Then, the tandem system management unit 190 generates a print request to be described later based on the determination result.
The first control unit 170 and the tandem system management unit 190 are configured to include a CPU, a RAM, and a ROM, and the functions of the tandem system management unit 190 are realized by the first control unit 170 and the first state management unit 171. Of course it is good.

  The second image forming unit 200 includes a second paper feed tray control unit 211, a second print processing unit 220, a second paper transport unit 232, a second control unit 270, a second state management unit 271, and a rear A processing unit control unit 272 and a second image processing unit 280 are included.

The second paper feed tray control unit 211 performs control to feed paper from one of the G trays 210g to 210i included in the second paper feed tray 210.
The second paper transport unit 232 is a paper fed from the second paper feed tray 210 (a paper passing through the transport path T6) or a paper carried in from the first image forming unit 100 via the transport path switching unit 230. Control is performed to convey any one of the sheets (the sheet passing through the conveyance path T5) to the conveyance path T7 or T8. Further, the second paper transport unit 232 transports the paper that has been carried into the transport path switching unit 231 via the transport path T7 via the transport path switching unit 231 to the transport path T9 via the transport path T8. Or a control for switching between transport to the transport path T9 without passing through the transport path T8.

  The second control unit 270 controls the driving of the second paper feed tray control unit 211, the second print processing unit 220, the second paper transport unit 232, and the like according to the instruction signal transmitted from the second state management unit 271. .

  The second state management unit 271 manages (controls) the entire operation of the second image forming unit 200 based on an instruction from the tandem system management unit 190. Specifically, the second state management unit 271 transmits an instruction signal to the second image processing unit 280, and controls generation of an image for printing.

  The post-processing unit control unit 272 transmits an instruction signal to the post-processing unit 400 to perform necessary post-processing on the paper that is carried out through the transport path T9.

  The second image processing unit 280 performs various image processing according to the instruction signal transmitted from the second state management unit 271 and generates an image for printing. The image generated by the second image processing unit 280 is formed on the paper by the second image forming unit 221.

About print processing
Next, print processing executed by the tandem system management unit 190 will be described. Here, when the tandem system management unit 190 acquires a print job or receives a print instruction from the user via the display operation unit 160, the tandem system management unit 190 prints a print request for each sheet to be printed (hereinafter referred to as a target sheet). Is generated and stored in a RAM or the like. The print request includes setting information regarding various print processes set by the user for the target paper. Specifically, the print request includes print processing information regarding whether single-sided printing processing or double-sided printing processing is performed on the target paper, tray information about a tray that feeds the target paper, and the amount of paper stored in each tray. Information on the volume.

(When feeding target paper from G tray to I tray and performing single-sided printing)
A case will be described in which the tandem system management unit 190 acquires print processing information from a print request for a target paper and performs single-sided printing processing on the target paper.

First, the tandem system management unit 190 acquires tray information from a print request, and specifies a tray for feeding the target paper.
It is assumed that the tray specified by the tandem system management unit 190 is one of the G tray 210g to the I tray 210i included in the second paper feed tray 210. In this case, the tandem system management unit 190 executes the printing process so that the target sheet follows a route as indicated by an arrow in FIG.
Specifically, the tandem system management unit 190 feeds the target paper from any one of the G tray 210g to the I tray 210i via the second paper feed tray control unit 211. Next, the tandem system management unit 190 carries the fed target paper into the transport path T7 via the transport path T6 via the second paper transport section 232. Next, the tandem system management unit 190 forms an image (toner image) generated by the second image processing unit 280 on the target sheet via the second image forming unit 221. Next, the tandem system management unit 190 heat-fixes the image on the target sheet via the second fixing unit 222. Then, the tandem system management unit 190 transports the target paper to the transport path T9 via the second paper transport unit 232, and transports the target paper to the post-processing unit 400. The post-processing unit 400 performs predetermined post-processing. Eject paper.

By the way, the tandem system management unit 190 acquires the amount information from the print request for the target paper, and sets the fixing sheet passing speed of the second image forming unit 200 according to the amount of the target paper when performing the above-described print processing. This is because when the target paper is a paper having a large amount of paper as compared with plain paper, such as a thick paper, a necessary heat amount representing a heat amount necessary for fixing an image on the target paper is increased.
That is, as the amount of wrinkles on the target sheet increases, the necessary heat amount also increases. Therefore, unless the fixing sheet passing speed of the second image forming unit 200 is decreased, the fixing heat amount of the second fixing unit 222 is less than the necessary heat amount. Therefore, as shown in FIG. 8, the tandem system management unit 190 increases the fixing paper passing speed of the second image forming unit 200 to 400 as the amount of the target paper increases as 64-130, 131-230, 231-330. (Mm / s), 300 (mm / s), and 200 (mm / s).

(When the target paper is fed from A tray to F tray and single-sided printing is performed)
Next, the tray specified by the tandem system management unit 190 is one of the A trays 310a to C310c included in the sheet feeding unit 300 or the D tray 110d to F tray 110f included in the first sheet feeding tray 110. And
In this case, the tandem system management unit 190 determines whether the target sheet is a sheet having a large amount of paper as compared with plain paper or the like, such as cardboard. Specifically, the amount information of the target paper is acquired from the print request of the target paper, and the amount of the target paper (set in the paper stored in the specified tray) is a predetermined value (for example, 131 g / m ² ) or more. Judge whether or not.

When the tandem system management unit 190 determines that the amount of the target paper is less than the predetermined value, the tandem system management unit 190 executes a printing process in which the target paper follows the path indicated by the arrow in FIG. If it is determined that the value is equal to or greater than the predetermined value, a printing process is performed in which the target sheet follows a route as indicated by an arrow in FIG.
That is, the tandem system management unit 190, when the amount of the target paper is less than the predetermined value, does not reduce the fixing paper passing speed of the first image forming unit 100, and the fixing heat amount of the first image forming unit 100 sets the necessary heat amount. In order to satisfy this condition, the target sheet is heated and fixed only by the first fixing unit 122. On the other hand, the tandem system management unit 190 performs heat fixing of the target paper by using both the first fixing unit 122 and the second fixing unit 222 when the amount of the target paper is greater than or equal to a predetermined value, so that the target paper The amount of heat to be applied to the first image forming unit 100 is dispersed to maintain the fixing paper passing speed of the first image forming unit 100.
In FIG. 6, the tandem system management unit 190 uses the second sheet transport unit 232 to unify the front and back surfaces of the target sheet in order to unify the front and back directions of each sheet at the time of sheet output (discharge). Is reversed by the transport path T8. However, the tandem system management unit 190 may of course be configured so that the front and back surfaces of the target paper are reversed by the transport path T4 via the first paper transport unit 132. However, in the configuration of the image forming apparatus 1, when the conveyance time is shorter when the sheet is conveyed to the conveyance path T8 than when the sheet is conveyed to the conveyance path T7, (1) from the single-sided printing process of the target sheet whose dredging amount is lower than the predetermined value. A case where the printing process is switched to the double-sided printing process of the target paper, and (2) a case where the printing process is switched from the single-sided printing process of the target paper whose dredging amount is lower than a predetermined value to the single-sided printing process of the target paper whose dredging amount is a predetermined value or more, In this case, since the gap between sheets at the time of switching is narrowed, it is more advantageous to reverse the direction by the transport path T8.

  Below, the tandem system management unit 190 determines that the amount of wrinkles of the target paper is below a predetermined value (when it is determined that the fixing heat amount of the first image forming unit 100 satisfies the required heat amount), and determines that the amount is greater than the predetermined value. A specific print processing procedure executed in each case (determined that the required heat amount is larger than the fixing heat amount of the first image forming unit 100) will be described.

First, if the tandem system management unit 190 determines that the amount of the target paper is less than the predetermined value, the tandem system management unit 190 receives the A via the first paper feed tray control unit 111 or the paper feed unit control unit 172 as shown in FIG. The target paper is fed from any of the trays 310a to 110f. Next, the tandem system management unit 190 carries the fed target paper into the transport path T3 via the transport path T1 or T2 via the first paper transport section 132. Next, the tandem system management unit 190 forms an image (toner image) generated by the first image processing unit 180 on the target sheet via the first image forming unit 121. Next, the tandem system management unit 190 heat-fixes the image on the target sheet via the first fixing unit 122.
Next, the tandem system management unit 190 carries the target paper into the second image forming unit 200 via the first paper transport unit 132 via the transport path T5. Next, the tandem system management unit 190 passes the second paper transport unit 232 via the transport path T8 as a bypass transport path so that the target paper does not follow the second print processing unit 220. Then, the tandem system management unit 190 carries in the post-processing unit 400 via the transport path T9, performs predetermined post-processing in the post-processing unit 400, and discharges the paper.
In this case, as shown in FIG. 8, the tandem system management unit 190 has the amount of paper of the target sheet equal to or less than a predetermined value (64 to 130), and thus the heat fixing by the second image forming unit 200 (second fixing unit 222). It can be seen that the fixing paper passing speed of the first image forming unit 100 can be maintained at a high speed of 400 (mm / s) without performing the above.

  Next, when the tandem system management unit 190 determines that the amount of the target paper is larger than the predetermined value, as illustrated in FIG. 7, the first tandem system management unit 190 passes the first paper feed tray control unit 111 or the paper feed unit control unit 172. The target paper is fed from any one of the A tray 310a to the F tray 110f. Next, the tandem system management unit 190 carries the fed target paper into the transport path T3 via the transport path T1 or T2 via the first paper transport section 132. Next, the tandem system management unit 190 forms an image (toner image) generated by the first image processing unit 180 on the target sheet via the first image forming unit 121.

  Next, the tandem system management unit 190 heat-fixes the image on the target sheet via the first fixing unit 122. Here, in order to keep the fixing paper passing speed of the first image forming unit 100 high, the fixing heat amount of the first image forming unit 100 is assumed to be lower than the necessary heat amount. Therefore, the first fixing unit 122 does not completely heat and fix the image on the target paper.

  Next, the tandem system management unit 190 reverses the front and back surfaces of the target paper via the first paper transport unit 132 via the transport path T4. Here, when the target paper is carried into the second image forming unit 200 without inverting the front and back surfaces, the first fixing unit 122 and the second fixing unit 222 press the same surface of the target paper with the fixing roller. The curled state is easily excited on the target paper. Therefore, as described above, the tandem system management unit 190 prevents the curling state from being excited by bringing the target paper with the front and back surfaces reversed into the second image forming unit 200.

  Next, the tandem system management unit 190 carries the target paper into the second image forming unit 200 via the first paper transport unit 132 via the transport path T5. Next, the tandem system management unit 190 transports the target paper to the transport path T7 via the second paper transport unit 232. Here, the tandem system management unit 190 controls the second image forming unit 221 not to form an image on the target paper when the target paper is passed through the second image forming unit 221. Specifically, the tandem system management unit 190 stops driving after separating the toner image generation unit 2211 from the intermediate transfer belt 2212. However, the intermediate transfer belt 2212 is maintained in a drivable state. That is, the tandem system management unit 190 stops the toner image generation unit 2211, thereby improving the lifetime of each component such as the photosensitive drum provided in the toner image generation unit 2211 and reducing the power consumption of the image forming apparatus 1. Thus, the target sheet can be reliably conveyed to the second fixing unit 222 by driving the intermediate transfer belt 2212.

Next, the tandem system management unit 190 heat-fixes the image formed by the first image forming unit 121 on the target sheet via the second fixing unit 222. That is, an amount obtained by subtracting the amount of heat of heating of the first image forming unit 100 from the amount of necessary heat is supplemented by the second fixing unit 222. The second fixing unit 222 completely heats and fixes the image on the target paper.
Then, the tandem system management unit 190 carries the target paper into the post-processing unit 400 via the transport path T9 via the second paper transport unit 232, and performs a predetermined post-processing by the post-processing unit 400. Eject paper.

The fixing sheet passing speed and fixing temperature of the first image forming unit 100 and the second image forming unit 200 in this case are shown in FIG. As shown in FIG. 8, the tandem system management unit 190 supplies the target paper from any one of the G tray 210g to the I tray 210i even when the amount of the target paper is greater than or equal to a predetermined value (131 to 230, 231 to 330). The fixing paper passing speed can be set faster than the single-sided printing process for paper. This is because the tandem system management unit 190 distributes the necessary heat amount between the fixing heat amount of the first image forming unit 100 and the fixing heat amount of the second image forming unit 200.
Note that when the amount of the target paper is 231 to 330, the tandem system management unit 190 sets the fixing sheet passing speed of the second image forming unit 200 to be higher than the fixing sheet passing speed of the first image forming unit 100. This is because the target paper is kept warm to some extent by the amount of heat applied to the first fixing unit 122 when the target paper is carried into the second image forming unit 200.

(When performing duplex printing)
Next, a case where the tandem system management unit 190 acquires print processing information from the print request for the target paper and performs double-sided print processing on the target paper will be described.
First, the tandem system management unit 190 acquires tray information from the print request, and specifies the tray that feeds the target paper from any one of the A tray 310a to the F tray 110f.
Then, the tandem system management unit 190 displays the target paper as shown in FIG. 7 in the same manner as in the single-sided printing process when the target paper has a predetermined amount or more and the target paper is fed from any one of the A tray 310a to the F tray 110f. The printing process is executed so as to follow the route indicated by the arrow. However, unlike the single-sided printing process, the tandem system management unit 190 performs control so that the image generated by the second image forming unit 280 is formed on the target paper when the target paper is passed through the second image forming unit 221. . Specifically, the tandem system management unit 190 brings the toner image generation unit 2211 into a driving state by bringing the toner image generation unit 2211 into close contact with the intermediate transfer belt 2212.
The fixing sheet passing speed and fixing temperature of the first image forming unit 100 and the second image forming unit 200 in this case are shown in FIG. As shown in FIG. 8, since the required heat amount increases as the amount of the target paper increases as 64-130, 131-230, 231-330, the tandem system management unit 190 fixes the sheet passing speed of each image forming unit. It can be seen that the values are set as low as 400, 420 (mm / s), 300, 315 (mm / s), and 200, 215 (mm / s).
The reason why the tandem system management unit 190 sets the fixing sheet passing speed of the second image forming unit 200 to be higher than the fixing sheet passing speed of the first image forming unit 100 is that the target sheet is in the second image forming unit 200. This is because the target sheet is kept warm to some extent by the amount of heat applied to the first fixing unit 122 when it is carried in.

"Notification process when tray weight is set"
Next, notification processing performed by the tandem system management unit 190 when the user sets the amount of paper stored in each tray (A tray 310a to I tray 210i) will be described.
The tandem system management unit 190 displays the standard screen 500 shown in FIG. 9 via the display operation unit 160 in a state where the first image forming unit 100 is activated. The standard screen 500 includes a tray setting button 510 in which the name of the tray, the paper size of the paper to be stored, and the amount of paper are described for each tray. For example, when the user presses the tray setting button 510h of the H tray 210h in the tray setting button 510, the tandem system management unit 190 displays a tray amount setting screen 520 shown in FIG. In the tray amount setting screen 520, a plurality of amount categories 521 to be set for the tray corresponding to the pressed tray setting button 510 are displayed. The user can set the amount of paper to be stored in each tray by selecting / determining one amount of weight category from the weight amount category 521. Here, a notification column 522 is provided on the tray amount setting screen 520. Then, via the notification column 522, a sheet whose amount of paper is greater than or equal to a predetermined value (131 g / m ² ) is accommodated in any one of the A tray 310a to the F tray 110f, so that the paper exceeding the amount of paper is printed on one side. The user is notified that the productivity in the case of processing is improved. Therefore, the user can appropriately set the amount of paper stored in each tray by referring to the notification column 522.
Note that the amount set by the user via the tray amount setting screen 520 is output to the tandem system management unit 190 as the amount information.

(Printing process)
Next, the printing process executed by the image forming apparatus 1 according to the present invention will be described with reference to the flowcharts of FIGS.

First, when the tandem system management unit 190 acquires a print job or reads an original image from the scanner 150, the tandem system management unit 190 acquires a print request for the target paper (step S1).
Next, the tandem system management unit 190 determines whether to perform single-sided printing processing on the target paper based on the print processing information of the print request (step S2).
If the tandem system management unit 190 determines in step S2 that single-sided printing processing is to be performed (step S2; Yes), the tray that feeds the target paper is based on the tray information of the print request. It is determined whether the tray is one of the F trays 110f (step S3).

  Next, when the tandem system management unit 190 determines in step S3 that the tray is one of the A tray 310a to the F tray 110f (step S3; Yes), the tandem system management unit 190 determines the target sheet based on the amount information of the print request. The amount of dredging is specified (step S4).

When the tandem system management unit 190 determines in step S4 that the amount of curling of the target sheet is 64 to 130 (step S4; 1.64 to 130), the fixing sheet passing speed of the first image forming unit 100 is set. 400 (mm / s) is set (step S5). Next, the tandem system management unit 190 sets the fixing temperature of the first image forming unit 100 to 180 (° C.) (step S6).
Next, the tandem system management unit 190 passes the second paper transport unit 232 from the transport path T7 to the transport path so that the target paper carried into the second image forming unit 200 does not follow the second print processing unit 220. A switching process to the T8 side is performed (step S7). Then, the tandem system management unit 190 performs a single-sided printing process on the target paper and ends this process.

  On the other hand, when the tandem system management unit 190 determines in step S4 that the amount of the target paper is 131 to 230 (step S4; 2.131 to 230), the fixing paper passing speed of the first image forming unit 100 is determined. Is set to 400 (mm / s) (step S8). Next, the tandem system management unit 190 sets the fixing temperature of the first image forming unit 100 to 185 (° C.) (step S9). Next, the tandem system management unit 190 sets the fixing sheet passing speed of the second image forming unit 200 to 400 (mm / s) (step S10). Next, the tandem system management unit 190 sets the fixing temperature of the second image forming unit 200 to 185 (° C.) (step S11), and proceeds to the process of step S16.

  Further, when the tandem system management unit 190 determines in step S4 that the amount of curling of the target paper is 231 to 330 (step S4; 3.231 to 330), the fixing paper passing speed of the first image forming unit 100 is set. 300 (mm / s) is set (step S12). Next, the tandem system management unit 190 sets the fixing temperature of the first image forming unit 100 to 190 (° C.) (step S13). Next, the tandem system management unit 190 sets the fixing sheet passing speed of the second image forming unit 200 to 400 (mm / s) (step S14). Next, the tandem system management unit 190 sets the fixing temperature of the second image forming unit 200 to 190 (° C.) (step S15).

Next, the tandem system management unit 190 performs reversal setting of the target paper in the first image forming unit 100 (step S16). That is, the tandem system management unit 190 switches the conveyance path so as to invert the front and back surfaces of the target sheet via the conveyance path T4.
Next, the tandem system management unit 190 passes the second paper transport unit 232 from the transport path T8 to the transport path T7 so that the target paper carried into the second image forming unit 200 follows the second print processing unit 220. Switching to the side is performed (step S17).
Next, the tandem system management unit 190 separates the toner image generation unit 2211 from the intermediate transfer belt 2212 and stops driving (step S18). At this time, the tandem system management unit 190 maintains the intermediate transfer belt 2212 in a drivable state.
Then, the tandem system management unit 190 executes a single-sided printing process in which the target sheet is heated and fixed using both the first fixing unit 122 and the second fixing unit 222, and ends this process.

  Next, when the tandem system management unit 190 determines in step S2 that the single-sided printing process is not performed (that is, the double-sided printing process is performed) (step S2; No), as illustrated in FIG. Based on this, the amount of wrinkle of the target paper is specified (step S21). Here, since the tray for feeding the target paper is duplex printing, it is one of the A tray 310a to the F tray 110f.

  When the tandem system management unit 190 determines in step S21 that the amount of the target paper is 64 to 130 (step S21; 1.64 to 130), the tandem system management unit 190 determines the fixing paper passing speed of the first image forming unit 100. 400 (mm / s) is set (step S22). Next, the tandem system management unit 190 sets the fixing temperature of the first image forming unit 100 to 180 (° C.) (step S23). Next, the tandem system management unit 190 sets the fixing sheet passing speed of the second image forming unit 200 to 420 (mm / s) (step S24). Next, the tandem system management unit 190 sets the fixing temperature of the second image forming unit 200 to 180 (° C.) (step S25), and proceeds to the process of step S34.

  On the other hand, when the tandem system management unit 190 determines in step S21 that the amount of the target paper is 131 to 230 (step S21; 2.131 to 230), the fixing sheet passing speed of the first image forming unit 100 is determined. Is set to 300 (mm / s) (step S26). Next, the tandem system management unit 190 sets the fixing temperature of the first image forming unit 100 to 185 (° C.) (step S27). Next, the tandem system management unit 190 sets the fixing sheet passing speed of the second image forming unit 200 to 315 (mm / s) (step S28). Next, the tandem system management unit 190 sets the fixing temperature of the second image forming unit 200 to 185 (° C.) (step S29), and proceeds to the process of step S34.

  If the tandem system management unit 190 determines in step S21 that the amount of curling of the target sheet is 231 to 330 (step S21; 3.231 to 330), the fixing sheet passing speed of the first image forming unit 100 is set. It is set to 200 (mm / s) (step S30). Next, the tandem system management unit 190 sets the fixing temperature of the first image forming unit 100 to 190 (° C.) (step S31). Next, the tandem system management unit 190 sets the fixing sheet passing speed of the second image forming unit 200 to 210 (mm / s) (step S32). Next, the tandem system management unit 190 sets the fixing temperature of the second image forming unit 200 to 190 (° C.) (step S33).

  Next, the tandem system management unit 190 passes the second paper transport unit 232 from the transport path T8 to the transport path T7 so that the target paper carried into the second image forming unit 200 follows the second print processing unit 220. Switching to the side is performed (step S34). At this time, the tandem system management unit 190 brings the toner image generation unit 2211 into a driving state after bringing the toner image generation unit 2211 into close contact with the intermediate transfer belt 2212. Then, the tandem system management unit 190 performs a double-sided printing process on the target paper and ends this process.

  Next, when the tandem system management unit 190 determines in step S3 that the tray is not one of the A tray 310a to the F tray 110f (that is, any tray of the G tray 210g to the I tray 210i) (step S3). S3; No), as shown in FIG. 13, the amount of the target paper is specified based on the amount information of the print request (step S41).

  When the tandem system management unit 190 determines in step S41 that the amount of the target paper is 64 to 130 (step S41; 1.64 to 130), the tandem system management unit 190 determines the fixing sheet passing speed of the second image forming unit 200. 400 (mm / s) is set (step S42). Next, the tandem system management unit 190 sets the fixing temperature of the second image forming unit 200 to 180 (° C.) (step S43), and proceeds to the process of step S48.

  On the other hand, when the tandem system management unit 190 determines in step S41 that the amount of the target paper is 131 to 230 (step S41; 2.131 to 230), the fixing sheet passing speed of the second image forming unit 200 is determined. Is set to 300 (mm / s) (step S44). Next, the tandem system management unit 190 sets the fixing temperature of the second image forming unit 200 to 185 (° C.) (step S45), and proceeds to the process of step S48.

  If the tandem system management unit 190 determines in step S41 that the amount of wrinkles in the target sheet is 231 to 330 (step S41; 3.231 to 330), the fixing sheet passing speed of the first image forming unit 100 is set. It is set to 200 (mm / s) (step S46). Next, the tandem system management unit 190 sets the fixing temperature of the second image forming unit 200 to 190 (° C.) (step S47).

  Next, the tandem system management unit 190 transports the target sheet fed from the G tray 210g to the I tray 210i from the transport path T8 via the second sheet transport unit 232 so that the target sheet follows the second print processing unit 220. Switching processing to the road T7 side is performed (step S48). At this time, the tandem system management unit 190 brings the toner image generation unit 2211 into a driving state after bringing the toner image generation unit 2211 into close contact with the intermediate transfer belt 2212. Then, the tandem system management unit 190 performs a single-sided printing process on the target paper and ends this process.

As described above, according to the image forming apparatus 1 according to the present embodiment, the tandem system management unit 190 feeds the target paper from the A tray 310a to the F tray 110f and performs single-sided printing processing by the first fixing unit 122. Then, the target sheet is conveyed to the second image forming unit 200, and the target sheet is heated and fixed by the second fixing unit 222.
Therefore, in the image forming apparatus 1, even when the required heat amount of the target paper is larger than that of plain paper such as thick paper, the required heat amount is distributed in both the first image forming unit 100 and the second image forming unit 200. Therefore, the fixing paper passing speed can be maintained at a higher speed than when the necessary heat amount is applied only by the first image forming unit 100 or the second image forming unit 200.
Therefore, the present invention is an image forming apparatus that can reliably heat and fix an image on a sheet without reducing productivity for printing processing of a sheet having a large amount of heat necessary for heat fixing.

Further, when the tandem system management unit 190 feeds the target paper from the A tray to the F tray and performs single-sided printing processing, the second image forming unit 221 causes the second image forming unit 221 to pass the target paper through the second image forming unit 221. Control is performed so that an image is not formed on the target paper.
For this reason, the image forming apparatus 1 can stop the toner image generation unit 2211 to improve the life of each component included in the toner image generation unit 2211 and to reduce the power consumption of the image forming apparatus 1.

In addition, when the tandem system management unit 190 determines that the required heat amount is larger than the fixing heat amount of the first image forming unit 100, the second fixing unit 222 performs heat fixing of the target sheet.
For this reason, the image forming apparatus 1 determines whether or not the fixing sheet passing speed of the first image forming unit 100 is lowered when the fixing heating is performed only by the first image forming unit 100. The target fixing sheet 222 can be heated and fixed by the second fixing unit 222.

Further, the tandem system management unit 190 feeds the target paper from the A tray to the F tray and performs single-sided printing processing. When the amount of the target paper is greater than or equal to a predetermined value (131 g / m ² ), the first image formation is performed. It is determined that the necessary heat amount is larger than the fixing heat amount of the unit 100.
For this reason, the image forming apparatus 1 can suitably specify a case where the amount of heat required inevitably increases because the amount of wrinkles is larger than that of plain paper, such as thick paper.

In addition, the tandem system management unit 190 stores the paper whose amount of paper is a predetermined value or more in any one of the A tray 310a to the F tray 110f via the notification column 522 of the tray amount setting screen 520, so The user is notified that the productivity in the case of single-sided printing of the above paper is improved.
Therefore, the user can appropriately set the amount of paper to be stored in each tray in consideration of the productivity with respect to the print processing of the target paper by referring to the notification column 522.

In addition, when the target sheet is fed from the A tray to the F tray and performs single-sided printing processing, the tandem system management unit 190 keeps the target sheet warm to some extent by the amount of heat applied to the first fixing unit 122. The fixing sheet passing speed of the two image forming unit 200 can be set higher than the fixing sheet passing speed of the first image forming unit 100.
Therefore, the image forming apparatus 1 can more suitably increase the productivity for printing processing of a sheet having a large amount of heat necessary for heat fixing.

Further, the tandem system management unit 190 switches the conveyance path so as to invert the front and back surfaces of the target paper via the conveyance path T4.
Therefore, the image forming apparatus 1 can prevent the curled state from being excited on the target paper.

The description in the above embodiment is an example of a suitable image forming apparatus according to the present invention, and the present invention is not limited to this.
Further, the detailed configuration and detailed operation of each part constituting the image forming apparatus in the above embodiment can be changed as appropriate without departing from the spirit of the present invention.

  Specifically, for example, in the above-described embodiment, the tandem system management unit 190 heats the target sheet using both the first fixing unit 122 and the second fixing unit 222 when the weight of the target sheet is a predetermined value or more. It was configured to fix. However, the tandem system management unit 190 uses both of the above when the target paper type (for example, plain paper, color dedicated paper, coated paper) is a specific paper type in addition to the amount of the target paper. Of course, the sheet may be configured to be heat-fixed. In other words, a paper made of a specific paper type such as coated paper has a low fixability even if the thickness of the paper itself is thin, and may require a large amount of heat in consideration of image quality at the time of paper discharge. Therefore, in such a case, the image forming apparatus 1 is configured to perform the heat fixing of the target paper using both of the above, so that the image forming apparatus 1 can more reliably make the paper without reducing the productivity for the paper printing process. The image can be fixed by heating.

Further, in the image forming apparatus 1, the first image forming unit 100 and the second image forming unit 200 each execute the printing process on one side of the paper, but can execute the printing process on both sides of the paper. You may comprise. With this configuration, when the tandem system management unit 190 executes the double-sided printing process, the first image forming unit 100 executes the printing process on both sides of the target paper whose weight is equal to or greater than a predetermined value, and then performs the second printing process. The image forming unit 200 (second fixing unit 222) can be controlled to heat and fix the target paper.
That is, the tandem system management unit 190 determines that the required heat amount is larger than the fixing heat amount of the first image forming unit 100 even when performing the double-sided printing process on the target paper, and the first fixing unit 122 and the second fixing unit 222. Since both of these are used to heat and fix the target paper, the amount of heat to be applied to the target paper can be dispersed to maintain the fixing paper passing speed of the first print processing unit 120.

In the above embodiment, the tandem system management unit 190 stops driving the toner image generation unit 2211 so that the second image forming unit 221 does not form an image on the target paper when the amount of the target paper is greater than or equal to a predetermined value. On the other hand, control was performed so as to maintain the intermediate transfer belt 2212 in a drivable state.
However, the tandem system management unit 190 compares the distance between the registration roller 2213 and the second fixing unit 222 with the length in the conveyance direction of the target paper, and stops the intermediate transfer belt 2212 from driving and the intermediate transfer belt 2212. It may be configured to switch between the case where the state is maintained in a drivable state. That is, when the length of the target paper in the conveyance direction is sufficiently longer than the distance between the registration roller 2213 and the second fixing unit 222, the target paper carried out from the second image forming unit 221 is transferred to the second fixing unit 222. When transporting, the intermediate transfer belt 2212 can be transported to the second fixing unit 222 by the action of the registration roller 2213 and the guide plate 2214 without driving. Therefore, in the above case, the tandem system management unit 190 can also stop driving of the intermediate transfer belt 2212, thereby improving the life of the intermediate transfer belt 2212 and further reducing the power consumption of the image forming apparatus 1. .

Further, in the image forming apparatus 1, when the amount of paper to be subjected to single-sided printing processing is greater than or equal to a predetermined value, as shown in FIG. 8, the target paper is fed from the A tray 310a to the F tray 110f by the G tray 210g. The fixing paper passing speed can be improved as compared with the case of feeding from the I tray 210i. However, the conveyance distance of the target paper is shorter when the paper is fed from the G tray 210g to the I tray 210i than when the paper is fed from the A tray 310a to the F tray 110f.
Therefore, the tandem system management unit 190 feeds the target paper from each tray in consideration of both the fixing paper passing speed and the transport distance when the amount of paper to be subjected to single-sided printing processing exceeds a predetermined value. Based on the total time from the time point until the paper is discharged via the paper discharge trays 411 and 412, it may be determined which of the trays is fed most to improve productivity.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 100 1st image forming unit 110 1st paper feed tray 110d-110f D tray-F tray 120 1st printing process part 121 1st image forming part 122 1st fixing | fixed part 131 Conveyance path switching part 132 1st paper Transport unit 160 Display operation unit 171 First state management unit 190 Tandem system management unit 200 Second image forming unit 210 Second paper feed trays 210g to 210i G tray to I tray 220 Second print processing unit 221 Second image forming unit 2211 Toner image generation unit 2212 Intermediate transfer belt 222 Second fixing unit 230 Conveyance path switching unit 300 Paper feed unit 310 Paper feed unit trays 310a to 310c A tray to C tray 400 Post-processing unit

Claims (7)

An image forming apparatus in which a plurality of image forming units are connected in series,
Each of the plurality of image forming units includes a fixing unit that applies a predetermined amount of fixing heat to a sheet and executes heat fixing of an image formed on the sheet,
The image is formed by one image forming unit among the plurality of image forming units, and the fixing unit included in the one image forming unit performs heat fixing of the image formed on the sheet, and then the sheet is loaded. An image forming system comprising: a control unit that performs control to carry out heat-fixing by a fixing unit included in the subsequent-stage image forming unit that is transported to a subsequent-stage image forming unit that is connected to the subsequent stage from the one image forming unit. apparatus. The image forming apparatus according to claim 1,
Each of the plurality of image forming units has an image forming unit that forms an image on a sheet,
The control unit heats and fixes the fixing unit included in the subsequent image forming unit without causing the image forming unit included in the subsequent image forming unit to form the image when the sheet is conveyed to the subsequent image forming unit. An image forming apparatus that performs control to be executed. The image forming apparatus according to claim 1, wherein
When the controller determines that the amount of heat necessary for fixing the image on the sheet is larger than the amount of heat of fixing of the fixing unit of the one image forming unit, the fixing of the latter-stage image forming unit is performed. An image forming apparatus that performs control for causing a part to perform heat fixing. The image forming apparatus according to claim 3, wherein
The control unit determines whether or not the amount of paper on which the image is formed is equal to or greater than a predetermined value, and when it is determined to be equal to or greater than the predetermined value, the amount of fixing heat of the fixing unit included in the one image forming unit An image forming apparatus characterized in that it is determined that the required heat quantity is larger than the above. The image forming apparatus according to claim 4,
A first paper feed unit for containing paper to be fed to the one image forming unit;
A second paper feed unit for containing paper to be fed to the subsequent image forming unit;
A notifying unit for notifying a user that the sheet whose amount of paper is greater than or equal to a predetermined value should be accommodated in the first sheet feeding unit;
An image forming apparatus comprising: An image forming apparatus according to any one of claims 1 to 5,
The control unit is configured such that the sheet conveyance speed when passing through the fixing unit included in the latter-stage image forming unit is faster than the sheet conveyance speed when passing through the fixing unit included in the one image forming unit. An image forming apparatus comprising: setting. The image forming apparatus according to any one of claims 1 to 6,
The control unit causes the fixing unit included in the one image forming unit to perform heat fixing and then reverses the front and back surfaces of the sheet, and then conveys the sheet to the fixing unit included in the subsequent image forming unit. An image forming apparatus.

Images