JP2012098477A - Image forming system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To match processing conditions for the preceding image forming apparatus and the subsequent image forming apparatus, in a tandem image forming system in which a plurality of image forming apparatuses are connected in series.SOLUTION: The ambient temperature T0 of the image forming system is obtained (S100), and also the temperature T2 of paper before a fixing process, which is fed from a paper feeding part of the preceding image forming apparatus, is obtained (S110). The ambient temperature T0 and the paper temperature T2 are compared, and the lower one is set as a target temperature T (S120 and so on). The paper temperature T2 after fixing is obtained (S140) and the determination is made whether the paper temperature T2 is almost equal to the target temperature T or not (S150). If the paper temperature T2 is higher than the target temperature T, the conveyance of the paper is temporarily stopped by an intermediate conveyance device and the paper is cooled by a cooling part (S200 and S210). After the paper is cooled, the determination is made whether the paper temperature T2 is almost equal to the target temperature T or not (S220). If the paper temperature T2 is almost equal to the target temperature, the paper is fed to a subsequent image forming apparatus 300 (S160).

Description

  The present invention relates to a tandem image forming system in which a plurality of image forming apparatuses are connected in series to perform duplex printing or the like.

  In recent years, a tandem type image forming system in which a plurality of image forming apparatuses are connected in series to perform double-sided printing or the like has been put into practical use. For example, in a tandem type image forming system in which two image forming apparatuses are connected, an image is formed on the surface of a sheet by a preceding image forming apparatus, and an intermediate conveying device provided between the preceding and succeeding image forming apparatuses. The paper is turned upside down, and an image is formed on the back side of the paper by a subsequent image forming apparatus. According to such an image forming system, the time loss at the time of switchback conveyance can be eliminated as compared with the case where double-sided printing is performed with one image forming apparatus, so that the printing speed can be improved.

  In Patent Document 1, when two-sided printing is performed with a plurality of printing apparatuses configured in tandem, images of the front and back surfaces of a sheet printed on both sides are measured by a sensor, and the front and back sides are measured based on the measurement result of the sensor. There has been proposed a printing apparatus that performs feedback control for optimally maintaining color reproducibility in both of the subsequent printing apparatuses. Japanese Patent Laid-Open No. 2004-228688 prints both inspection charts of the two printing units on the same surface of the paper in the inspection mode, and reads these inspection charts with a reading unit, so that color reproducibility between both print engines is obtained. There has been proposed a printing apparatus that determines whether or not the two match.

JP 2009-300703 A JP 2007-137010 A

  By the way, in the image forming apparatuses disclosed in Patent Documents 1 and 2, the sheet heated and pressurized (fixed) by the fixing unit of the preceding image forming apparatus is conveyed to the succeeding image forming apparatus. In some cases, the image forming apparatus in the preceding stage and the image forming apparatus in the succeeding stage may greatly differ in the sheet temperature during image formation. To solve this problem, the subsequent image forming apparatus changes process conditions such as chargeability, developability, toner density, and correction conditions based on the temperature of the paper carried from the previous image forming apparatus. It is conceivable to perform correction processing.

  However, as the process conditions of the subsequent image forming apparatus are changed, the process conditions of the previous image forming apparatus are different, so that there is a difference between the image formed in the previous stage and the image formed in the subsequent stage. There is a problem of end. Further, in the latter-stage image forming apparatus, the internal temperature rises higher than the internal temperature of the preceding-stage image forming apparatus due to the carry-in of the fixed sheet, so that the number of corrections for the process conditions and the like increases, and the productivity is increased. There is a problem that will decrease.

  The above-described problems are not only when duplex printing is performed in a tandem image forming system, but also when different images and colors are continuously printed on the same surface of a sheet by the former and subsequent image forming apparatuses. Problems occur.

  Therefore, the present invention has been made in view of the above problems, and in a tandem type image forming system in which a plurality of image forming apparatuses are connected in series, the processes of the image forming apparatus at the preceding stage and the image forming apparatus at the subsequent stage. An object of the present invention is to provide an image forming system capable of automatically adjusting conditions.

  In order to solve the above-described problems, an image forming system according to the present invention includes a first image forming unit that forms an image on a sheet and a fixing unit that fixes the image formed by the image forming unit on the sheet. An image forming apparatus and a second image forming apparatus that is connected in series to the downstream side of the first image forming apparatus and has an image forming unit that forms an image on a sheet discharged from the first image forming apparatus. A tandem type image forming system provided in a conveyance path between a fixing unit of a first image forming apparatus and a second image forming apparatus, and adjusting a paper temperature of a sheet discharged from the fixing unit. A fixing sheet measuring unit for measuring, a cooling unit provided in a conveyance path between the fixing unit of the first image forming apparatus and the second image forming apparatus, for cooling the sheet discharged from the fixing unit, Provided in the first image forming apparatus or the second image forming apparatus. A control unit that controls the cooling unit based on the paper temperature measured by the paper measurement unit so that the paper temperature of the paper reaches a preset target temperature before the paper is carried into the second image forming apparatus. It is equipped with.

  In the present invention, a predetermined image is formed on a sheet by the image forming unit of the first image forming apparatus. The sheet is supplied from, for example, a sheet feeding unit provided inside the first image forming apparatus or a large-capacity sheet feeding device connected to the first image forming apparatus. The sheet on which the predetermined image is formed by the image forming unit is discharged from the first image forming apparatus after being subjected to a heating / pressurizing process (fixing process) by the fixing unit of the first image forming apparatus.

  The paper temperature of the paper discharged from the first image forming apparatus is measured by a fixing paper measuring unit provided downstream of the fixing unit. The control unit controls driving of the cooling unit so that the paper temperature of the paper measured by the fixing paper measurement unit becomes a preset target temperature. As a result, the paper temperature of the paper heated by the fixing unit is lowered to the target temperature and fed to the second image forming apparatus. The target temperature is a temperature that is set so that image forming conditions (process conditions) such as charging, exposure, and development of the second image forming apparatus match the image forming conditions of the first image forming apparatus. . The sheet lowered to the target temperature by the cooling unit is fed to the second image forming apparatus, and a predetermined image is formed by the image forming unit of the second image forming apparatus.

  The image forming apparatus according to the present invention performs double-sided printing by forming a predetermined image on the front surface of the sheet with the first image forming apparatus and forming a predetermined image on the back surface of the sheet with the second image forming apparatus. Or, when the first image forming apparatus and the second image forming apparatus continuously print different colors and images on the same surface of the paper.

  According to the present invention, the operation of the cooling unit is controlled so that the sheet temperature of the sheet fixed by the fixing unit of the first image forming apparatus becomes the target temperature, and the sheet is conveyed to the second image forming apparatus. Therefore, the process conditions of the second image forming apparatus can be matched with the process conditions of the first image forming apparatus. Thereby, variation in image quality between an image formed by the first image forming apparatus and an image formed by the second image forming apparatus can be prevented, and image quality can be improved.

  In addition, according to the present invention, since the increase in the internal temperature of the second image forming apparatus due to the carry-in of paper from the first image forming apparatus can be mitigated, the number of corrections of the second image forming apparatus can be suppressed, As a result, productivity can be improved.

1 is a diagram illustrating a configuration example of an image forming system according to a first embodiment of the present invention. 1 is a diagram illustrating a block configuration example of an image forming system. 3 is a flowchart illustrating an operation example of the image forming system. It is a figure which shows the structural example of the image forming system which concerns on the 2nd Embodiment of this invention.

Hereinafter, the best mode for carrying out the invention (hereinafter referred to as an embodiment) will be described.
<1. First Embodiment>
[Configuration example of image forming system]
FIG. 1 shows an example of the configuration of an image forming system 500A according to the present invention. As shown in FIG. 1, the image forming system 500 </ b> A includes a front-stage image forming apparatus 100, an intermediate conveyance apparatus 200, a rear-stage image forming apparatus 300, and a large-capacity paper feeding apparatus 400. The front-stage image forming apparatus 100 and the rear-stage image forming apparatus 300 are apparatuses having the same configuration and function, and are connected in series via the intermediate conveyance apparatus 200.

  The front-stage image forming apparatus 100 is an example of a first image forming apparatus, forms a predetermined image on the surface (first surface) of the paper P, performs a fixing process, and then transports it to the intermediate transport apparatus 200. . The intermediate transport apparatus 200 is an example of a transport apparatus, and includes a switchback mechanism unit. The intermediate transport apparatus 200 reverses the front and back of the paper P transported from the preceding image forming apparatus 100 and transports it to the subsequent image forming apparatus 300. The latter-stage image forming apparatus 300 is an example of a second image forming apparatus, and forms a predetermined image on the back surface (second surface) of the paper P and discharges it from the discharge unit 380 to the outside. As described above, by performing two-sided printing with the two image forming apparatuses 100 and 300 as a tandem configuration, it is possible to increase the printing speed.

(Configuration example of image forming apparatus)
As shown in FIG. 1, the image forming apparatus 100 in the previous stage includes an automatic document feeder 160, an image reading unit (not shown), an image forming unit 110, a fixing unit 120, a paper feeding unit 130, a temperature sensor unit 140, and a discharge unit 180. It has.

  The automatic document feeder 160 transports the document M placed on the document table to the image reading unit by the transport mechanism. The image reading unit scans and exposes an image on one side or both sides of the original M to read an image on the original M, supplies the read image data to the image forming unit 110 after performing analog processing, shading correction, image compression processing, and the like. To do.

  The image forming unit 110 includes a photosensitive drum 112 and a developing unit 114. The developing unit 114 includes, for example, a charging unit, an exposure unit, a developing unit, and a cleaning unit. The charging unit uniformly charges the peripheral surface of the photosensitive drum 112. The exposure unit irradiates the photosensitive drum 112 with laser light to form an electrostatic latent image on the surface thereof. The developing unit reveals the latent image formed on the surface of the photosensitive drum 112 as a toner image. In this example, a toner image is formed on the photosensitive drum 112 by an electrophotographic process, but the present invention is not limited to this.

  The paper feed unit 130 is composed of a plurality of paper feed trays. Each paper feed tray stores paper P of A4 size, B5 size, etc., and the paper P selected by the user is transported to the image forming unit 110 by transport rollers. The paper P conveyed from the paper supply unit 130 is synchronized with the toner image by a registration roller, and the transfer unit transfers the toner image (image) to the surface of the paper P, and the fixing unit 120 provided on the downstream side. It is conveyed to.

  The fixing unit 120 includes a heating roller and a pressure roller. A heat source (not shown) is built in the heating roller, and the heating roller is controlled to a constant temperature. The fixing unit 120 heats and pressurizes the toner image transferred to the surface of the paper P, thereby melting the toner image and fixing the toner image on the paper P. The sheet P on which the fixing process has been performed by the fixing unit 120 is conveyed from the discharge unit 180 to the adjacent intermediate conveyance device 200.

  The temperature sensor unit 140 is provided in a conveyance path between the paper feeding unit 130 and the image forming unit 110, and measures the paper temperature T1 of the paper P fed from the paper feeding unit 130 to the image forming unit 110. The paper temperature T <b> 1 indicates the temperature of the paper P before the fixing process is performed by the fixing unit 120. The temperature sensor unit 140 may be installed for each paper feed tray. The temperature sensor unit 140 constitutes an example of a paper feed sheet measuring unit, and a non-contact temperature sensor such as an infrared sensor or a thermopile is used.

  The front-stage image forming apparatus 100 includes a switchback mechanism for reversing the front and back of the paper P, and a refeed path for refeeding the paper P with the front and back reversed to the image forming unit 110. Here, when double-sided printing is performed by the preceding image forming apparatus 100 using the switchback mechanism or the like, the next paper P can be fed until the paper P is reversed and fed again. Therefore, a time loss occurs. Therefore, in this example, the image forming apparatus 100 in the previous stage is connected in series with the image forming apparatus 300 in the subsequent stage to perform double-sided printing, thereby improving productivity by increasing the printing speed.

(Configuration example of intermediate transfer device)
As shown in FIG. 1, the intermediate conveyance device 200 is arranged between the front-stage image forming apparatus 100 and the rear-stage image forming apparatus 300, and reverses the front and back of the paper P carried out from the front-stage image forming apparatus 100. (Switched back) and then fed to the subsequent image forming apparatus 300. The intermediate conveyance device 200 includes a paper carry-in unit 210, a stacking unit 220, a paper carry-out unit 212, a bypass conveyance unit 214, a temperature sensor unit 240, and a cooling unit 230.

  The paper carry-in unit 210 includes a conveyance roller and a guide plate, and sequentially carries the paper P discharged from the discharge unit 180 of the preceding image forming apparatus 100 into the intermediate conveyance device 200 and conveys it to the stacking unit 220.

  The stacking unit 220 includes two guide plates arranged in parallel in the vertical direction, a stop member, a vertical / horizontal alignment member, a carry-in drive roller, and a carry-out drive roller, and covers the front and back of the paper P carried from the paper carry-in unit 210. The paper is reversed and conveyed to the upper paper carry-out unit 212. Therefore, the stacking unit 220 functions as a switchback mechanism unit. Further, the stacking unit 220 stacks the paper P discharged from the fixing unit 120 for a predetermined time, that is, stops the conveyance of the paper P for a certain period, and the paper temperature T2 of the paper P reaches the predetermined temperature (target temperature T). Adjust so that it falls. Further, after stacking and aligning a plurality of sheets P carried from the sheet carry-in section 210, the stacking section 220 reverses the sheets P and carries them out to the upper sheet carry-out section 212.

  The paper carry-out unit 212 includes an intermediate conveyance roller, a paper discharge roller, and a guide plate, and conveys the paper P one by one to the subsequent image forming apparatus 300.

  The bypass conveyance unit 214 is a conveyance path extending in the horizontal direction from the paper carry-in unit 210. For example, the image forming apparatus 300 or a post-processing device (not shown) is not connected to the subsequent stage of the intermediate conveyance device 200, and post-processing is performed. This is used when it is unnecessary, or when it is not necessary to reverse the front and back of the paper P.

  The temperature sensor unit 240 is provided, for example, in the periphery of the stacking unit 220, and measures the paper temperature T2 of the paper P fixed by the fixing unit 120 of the preceding image forming apparatus 100. The installation location of the temperature sensor unit 240 is not limited to the peripheral portion of the stacking unit 220 as long as it can detect the paper temperature T2 of the paper P after fixing. The temperature sensor unit 240 constitutes an example of a fixing sheet measuring unit.

  The cooling unit 230 is provided, for example, in the periphery of the stacking unit 220, and includes a cooling fan or the like. When the paper temperature T2 of the paper P after the fixing process exceeds a normal range (target temperature T) as will be described later, the cooling unit 230 blows air on the paper P stacked in the stacking unit 220. It has a function of lowering the paper temperature of the paper P to a constant temperature. It should be noted that by adding a humidifying function to the cooling unit 230, the paper P curled by the fixing process in the preceding image forming apparatus 100 can be decurled. In this case, when the paper P is stacked on the stacking unit 220, the paper P is decurled by releasing moisture into the air.

(Configuration example of image forming apparatus in the latter stage)
As shown in FIG. 1, the latter-stage image forming apparatus 300 is disposed on the left side surface of the intermediate conveying apparatus 200 (on the downstream side of the former-stage image forming apparatus 100), and includes an automatic document conveying apparatus 360, an image reading unit (not shown), and an image. A forming unit 310, a fixing unit 320, a paper feeding unit 330, and a temperature sensor unit 370 are provided. The subsequent image forming apparatus 300 has the same configuration and function as the previous image forming apparatus 100, and thus detailed description thereof is omitted.

  The automatic document conveying device 360 conveys the document M placed on the document table to the image reading unit by the conveyance mechanism. The image reading unit scans and exposes an image on one side or both sides of the document M to read the image of the document M, and supplies the read image data to the image forming unit 310.

  The paper feed unit 330 is composed of a plurality of paper feed trays. Each paper feed tray accommodates paper P of A4 size, B5 size or the like. The paper feed unit 330 carries out the paper P selected by the user from the paper feed tray and transports it to the image forming unit 310 by the transport rollers.

  The image forming unit 310 includes a photosensitive drum 312 and a developing unit 314. The developing unit 314 includes, for example, a charging unit, an exposure unit, a developing unit, a cleaning unit, and the like. The paper P conveyed from the preceding image forming apparatus 100 is synchronized with the toner image by the registration roller, and the toner image (image) is transferred to the back surface of the paper P in the transfer unit.

  The fixing unit 320 includes a heating roller and a pressure roller, and heats and pressurizes the toner image transferred to the back surface of the paper P to melt the toner image and fix the toner image on the paper P. The paper P on which the fixing process has been performed by the fixing unit 320 is discharged from the discharge unit 380 to the outside.

  The temperature sensor unit 370 is installed outside the image forming system 500A and measures the outside air temperature T0 around the image forming system 500A. The temperature sensor unit 370 constitutes an example of an ambient temperature measurement unit.

(Configuration example of large capacity paper feeder)
As shown in FIG. 1, the large-capacity paper feeding device 400 is a device that stores and accommodates a large amount of paper P, and is disposed on the right side surface of the image forming apparatus 100 in the previous stage. The large-capacity paper feeding device 400 includes a paper feeding unit 430 and a temperature sensor unit 440. The paper feed unit 430 is configured by a plurality of paper feed trays, for example, containing a plurality of sizes of paper P, and transports the paper P one by one to the preceding image forming apparatus 100 based on the user's paper selection. . The temperature sensor unit 440 is provided, for example, in the vicinity of the discharge unit of the paper P, and measures the paper temperature T1 of the paper P fed from the paper feed unit 430 to the image forming apparatus 100.
[Example of block configuration of image forming system]
FIG. 2 shows an example of a block configuration of the image forming system 500A. As shown in FIG. 2, the image forming system 500 </ b> A includes a front-stage image forming apparatus 100, an intermediate conveyance apparatus 200, a rear-stage image forming apparatus 300, and a large-capacity paper feeding apparatus 400.

  The former image forming apparatus 100 includes a control unit 102 that controls the overall operation of the image forming apparatus 100. The control unit 102 includes a CPU (Central Processing Unit) 104, a ROM (Read Only Memory) 106, and a RAM (Random Access Memory) 108. The CPU 104 develops the program and data read from the ROM 106 on the RAM 108 and activates the program to control each unit of the image forming apparatus 100.

  The control unit 102 is connected to each of the image forming unit 110, the fixing unit 120, the paper feeding unit 130, the temperature sensor unit 140, and the communication unit 150. The image forming unit 110 executes an electrophotographic process such as charging, development, and exposure based on a control signal supplied from the control unit 102 and forms a predetermined image on the paper P conveyed from the paper supply unit 130.

  The fixing unit 120 heats and pressurizes the sheet P on which a predetermined image is transferred by the image forming unit 110 based on a control signal supplied from the control unit 102, and conveys the sheet P to the intermediate conveyance device 200.

  The paper feed unit 130 drives a conveyance roller or the like based on a control signal supplied from the control unit 102, and carries out the paper P selected by the user from the paper feed tray and feeds it to the image forming unit 110.

  The temperature sensor unit 140 measures the paper temperature T1 of the paper P before passing through the fixing unit 120 fed from the paper feeding unit 130 to the image forming unit 110 (before image formation), and measurement information obtained by the measurement. DT1 is supplied to the control unit 102.

  The communication unit 150 is connected to each of the communication units 250 and 450 of the intermediate conveyance device 200 and the large-capacity paper feeding device 400. The communication unit 150 functions as an input / output unit that establishes communication with the intermediate conveyance device 200 and the large-capacity paper feeding device 400. In this example, when a plurality of image forming apparatuses are connected in tandem, the rear stage control unit 302 of the rear stage image forming apparatus 300 mainly performs cooling control of the paper P and the like. The measured information DT1 is supplied to the subsequent control unit 302 of the subsequent image forming apparatus 300 via the communication units 150 and 250.

  The intermediate transport apparatus 200 includes a control unit 202 that controls the overall operation of the intermediate transport apparatus 200. The control unit 202 includes a CPU 204, a ROM 206, and a RAM 208. The control unit 202 is connected to each of the stacking unit 220, the temperature sensor unit 240, the cooling unit 230, and the communication unit 250.

  The stacking unit 220 stacks the sheets P conveyed from the preceding image forming apparatus 100 based on the control signal supplied from the control unit 202, and stops the conveyance of the sheets P for a certain period. Accordingly, since the cooling unit 230 is provided in the peripheral portion of the stacking unit 220, the cooling time by the cooling unit 230 can be secured for a long time by stacking the sheets P.

  The temperature sensor unit 240 measures the paper temperature T2 of the paper P that has been subjected to the fixing process by the fixing unit 120 of the preceding image forming apparatus 100, and supplies the measurement information DT2 obtained by the measurement to the control unit 202. Further, the temperature sensor unit 240 measures the paper temperature T2 of the paper P after being cooled by the cooling unit 230, and supplies the measurement information DT2 obtained by the measurement to the control unit 202.

  The cooling unit 230 drives the cooling fan based on the drive signal supplied from the control unit 202 and blows a predetermined amount of wind on the paper P conveyed to the stacking unit 220. As will be described later, the air blowing amount is determined based on the paper temperature T2 of the paper P after fixing. By the cooling unit 230, the paper temperature T1 of the paper P that has been raised by the heating process (fixing process) of the preceding fixing unit 120 can be lowered to the target temperature T.

  The subsequent image forming apparatus 300 includes a control unit 302 that controls the overall operation of the image forming apparatus 300. The control unit 302 includes a CPU 304, a ROM 306, and a RAM 308. The CPU 304 expands the program and data read from the ROM 306 on the RAM 308 and activates the program to control each unit of the image forming apparatus 300. The ROM 306 stores a target temperature T used for cooling control of the paper P.

  The control unit 302 is connected to each of an image forming unit 310, a fixing unit 320, a paper feeding unit 330, a temperature sensor unit 370, and a communication unit 350. The image forming unit 310 executes an electrophotographic process such as charging, development, and exposure based on a control signal supplied from the control unit 302, and forms a predetermined image on the paper P conveyed from the paper supply unit 330.

  The fixing unit 320 heats and pressurizes the paper P on which a predetermined image is transferred by the image forming unit 310 based on a control signal supplied from the control unit 302, and the double-side printed paper P from the discharge unit 380. Paper is discharged to the outside.

  The temperature sensor unit 370 is provided outside (around) the image forming system 500A, measures the outside air temperature T0 of the image forming system 500A, and supplies measurement information DT0 obtained by the measurement to the control unit 302.

  The post-stage control unit 302 includes a paper temperature T2 of the paper P after the fixing process measured by the temperature sensor unit 240 of the intermediate conveyance device 200 and a post-feeding unit measured by the temperature sensor unit 140 of the image forming apparatus 100 of the pre-stage. The paper temperature T1 or the outside air temperature T0 of the paper P is compared, and the air flow rate of the cooling unit 230 of the intermediate conveyance device 200 is controlled based on the comparison result (temperature difference).

  The communication unit 250 is connected to the communication unit 250 of the intermediate transfer device 200. The communication unit 350 functions as an input / output unit that establishes communication with the intermediate conveyance device 200 and the preceding image forming apparatus 100. In this example, as described above, since the post-stage control unit 302 performs the cooling control of the paper P, etc., the measurement information DT1, DT2 obtained by the measurement of the temperature sensor units 140, 240 is used for the communication units 150, 250. To the subsequent control unit 302 of the subsequent image forming apparatus 300.

  The large-capacity paper feeder 400 has a control unit 402 that controls the overall operation of the large-capacity paper feeder 400. The control unit 402 includes a CPU 404, a ROM 406, and a RAM 408. The CPU 404 develops the program and data read from the ROM 406 on the RAM 408 and activates the program to control each unit of the large capacity sheet feeding device 400.

  The control unit 402 is connected to each of a paper feed unit 430, a temperature sensor unit 440, and a communication unit 450. The paper feeding unit 430 drives a conveyance roller or the like based on a control signal supplied from the control unit 402, carries out the paper P selected by the user from the paper feeding tray, and feeds it to the preceding image forming apparatus 100. To do.

  The temperature sensor unit 440 measures the paper temperature T5 of the paper P conveyed from the paper supply unit 430 and supplies the measurement information DT5 obtained by the measurement to the control unit 402. The communication unit 450 is connected to the communication unit 150 of the preceding image forming apparatus 100. The communication unit 450 functions as an input / output unit that establishes communication with the image forming apparatus 100 in the previous stage, and transmits, for example, measurement information DT5 obtained by measurement of the temperature sensor unit 440 to the image forming apparatus 100 in the previous stage.

[Operation example of image forming system]
FIG. 3 is a flowchart illustrating an example of the operation of the image forming system 500A. In the following, a description will be given of a case where the latter control unit 302 of the latter image forming apparatus 300 is the main body and performs overall control of the image forming system 500A. Further, a case where the paper P is fed from the paper feeding unit 130 of the preceding image forming apparatus 100 will be described. In order to simplify the description, the control contents for each sheet are shown in this flow. However, when image formation is performed on a sheet by continuously feeding, the control in this flow is performed in parallel for each sheet. Done.

  As illustrated in FIG. 3, in step S100, the post-stage control unit 302 obtains the outside air temperature T0 around the image forming system 500A measured by the temperature sensor unit 370 installed outside the image forming system 500A. If outside temperature T0 is acquired, it will progress to Step S110.

  In step S <b> 110, the rear control unit 302 calculates the paper temperature T <b> 1 of the paper P before the fixing process fed from the paper feeding unit 130 to the image forming unit 110, measured by the temperature sensor unit 140 of the front image forming apparatus 100. get. If the paper temperature T1 of the paper P of the previous image forming apparatus 100 is acquired, the process proceeds to step S120.

  In step S120, the rear control unit 302 compares the outside air temperature T0 around the image forming system 500A with the paper temperature T1 of the paper P fed by the front image forming apparatus 100, and the outside air temperature T0 is greater than the paper temperature T1. Determine whether it is low. The post-stage control unit 302 proceeds to step S130 when determining that the outside air temperature T0 is lower than the paper temperature T1, and proceeds to step S190 when determining that the outside air temperature T0 is higher than the paper temperature T1.

  When the outside air temperature T0 is lower than the paper temperature T1, in step S130, the rear control unit 302 sets the target temperature T to the outside air temperature T0. On the other hand, when the outside air temperature T0 exceeds the paper temperature T1, the post-stage control unit 302 sets the target temperature T to the paper temperature T1 in step S190. The target temperature T is set to the lower temperature of the outside air temperature T0 or the paper temperature T1 in this way. When the paper temperature T1 is higher than the outside air temperature T0, the image forming system is adjusted to the outside air temperature T0. This is because the internal temperature of 500A can be kept low, and the number of corrections of process conditions can be reduced. Of course, the target temperature T can be set to the higher one of the outside air temperature T0 and the paper temperature T1.

  Here, the target temperature T is used to match the paper temperature T2 of the paper P conveyed to the subsequent image forming apparatus 300 with the paper temperature T1 of the paper P before being fixed by the previous image forming apparatus 100. This is the set temperature. That is, the temperature is set to match the process condition of the subsequent image forming apparatus 300 with the process condition of the preceding image forming apparatus 100.

  In step S140, the post-stage control unit 302 acquires the paper temperature T2 of the paper P measured by the temperature sensor unit 240 of the intermediate transport apparatus 200. The sheet P is a sheet that has been subjected to fixing processing by the fixing unit 120 of the preceding image forming apparatus 100 and then carried into the intermediate conveyance device 200. When the paper temperature T2 is acquired, the process proceeds to step S150.

  In step S150, the post-stage control unit 302 determines whether or not the preset target temperature T and the paper temperature T2 of the fixed paper P are substantially equal. That is, it is determined whether or not the paper temperature T2 of the paper P after the fixing process is within the allowable temperature range based on the preset target temperature T. When the post-stage control unit 302 determines that the target temperature T and the post-fixing paper temperature T2 are substantially equal, the post-control unit 302 proceeds to step S160 assuming that the paper temperature T2 of the paper P is within the normal range, and the post-fixing paper P If it is determined that the paper temperature T2 exceeds the allowable temperature range of the target temperature T, the process proceeds to step S200.

  When it is determined that the paper temperature T2 exceeds the target temperature T, in step S200, the post-stage control unit 302 controls the conveyance so that the conveyance of the paper P after the fixing process is temporarily stopped in the conveyance path to cool the paper P. . For example, the paper P after the fixing process is transported to the stacking unit 220 of the intermediate transport device 200, and the transport of the paper P is temporarily stopped by the stacking unit 220. Accordingly, it is possible to leave time until the paper P is fed to the image forming unit 310 of the subsequent image forming apparatus 300, and during that time, the temperature of the paper P is set to the target temperature T in combination with cooling by the cooling unit 230 described later. Can be lowered. The stop time of the paper P can be set in advance according to the temperature difference between the target temperature T and the paper temperature T2, and a correspondence table between the stop time and the temperature difference can be stored in the ROM 306, for example. The stop time is preferably set in consideration of the cooling effect by the cooling unit 230.

  Subsequently, in step S210, the post-stage control unit 302 turns on the cooling unit 230 and cools the sheet P that is temporarily stopped in the transport path by applying a predetermined amount of wind. Specifically, the sheet P is cooled by setting the air volume of the cooling unit 230 so that the sheet temperature T2 of the sheet P becomes substantially equal to the target temperature T. When the cooling process of the paper P is completed in step S210, the process proceeds to step S220.

  In step S220, the post-stage control unit 302 acquires the paper temperature T2 of the cooled paper P from the temperature sensor unit 240, and determines again whether or not the paper temperature T2 of the paper P is substantially equal to the target temperature T. If it is determined that the paper temperature T2 of the paper P is substantially equal to the target temperature T, the process proceeds to step S230. On the other hand, when it is determined that the paper temperature T2 of the paper P is still higher than the target temperature T, the conveyance of the paper P is temporarily stopped and the cooling unit is set so that the paper temperature T2 of the paper P becomes substantially equal to the target temperature T. The ventilation by 230 is continuously executed.

  When the paper temperature T2 of the paper P is lower than the target temperature T, the post-stage control unit 302 turns off the cooling unit 230 and stops blowing air to the paper P in step S230. After the cooling unit 230 is turned off, the post-stage control unit 302 proceeds to step S160.

  In step S <b> 160, the rear-stage control unit 302 feeds the paper P to the rear-stage image forming apparatus 300 by reversing the paper P with the stacking unit 220 of the intermediate conveyance device 200. The paper P includes paper (S150) in which the paper temperature T2 satisfies the target temperature T without being subjected to cooling processing, or paper (S200 to S230) in which the target temperature T is satisfied by cooling processing. When paper feeding to the subsequent image forming apparatus 300 of the paper P is completed, the process proceeds to step S170.

  In step S <b> 170, the rear control unit 302 forms a predetermined image on the back surface of the paper P fed from the intermediate conveyance device 200. Since the paper temperature T2 of the paper P fed to the subsequent image forming apparatus 300 is substantially the same as the paper temperature T1 at the time of image formation of the previous image forming apparatus 100, the rear control unit 302 performs image formation. The image on the back surface of the paper P is formed without changing the process to the image forming process of the image forming apparatus 100 at the preceding stage.

  If the post-stage control unit 302 determines in step S180 that the printing process (for example, all jobs) has ended, the series of processes ends. On the other hand, if it is determined that the printing process has not been completed, the process returns to step S100, and the above-described temperature control of the paper P is repeatedly executed for the next paper P to be fed. In the temperature control of the next sheet P, when the outside air temperature T0 is used as it is, the process may return to step S110. When the outside air temperature T0, the paper temperature T1, and the target temperature T are used as they are, the step S140 is performed. You may return to

  As described above, in the first embodiment, the paper temperature T2 of the paper P fixed by the fixing unit 120 of the preceding image forming apparatus 100 is driven to the target temperature T2 by driving the cooling fan of the cooling unit 230. And is conveyed to the subsequent image forming apparatus 300. For this reason, the paper temperature of the paper P at the time of image formation by the subsequent image forming apparatus 300 and the paper temperature of the paper P at the time of image formation by the previous image forming apparatus 100 can be substantially matched. The process conditions of the image forming apparatus 300 can be matched with the process conditions of the preceding image forming apparatus 100. As a result, a difference in image quality between an image formed by the preceding image forming apparatus 100 and an image formed by the subsequent image forming apparatus 300 can be prevented, and image quality can be improved.

Further, according to the first embodiment, the increase in the internal temperature of the subsequent image forming apparatus 300 due to the carry-in of the paper P from the previous image forming apparatus 100 can be mitigated. As a result, productivity can be improved.
<2. Second Embodiment>
In the second embodiment, the cooling control of the paper P is performed based on the paper temperature T3 of the paper P conveyed to the subsequent image forming apparatus 300 and the internal temperature T4 of the image forming apparatus 300 after the paper P is conveyed. This is different from the first embodiment in that it is performed. Since the configuration of the other image forming system 500B is the same as that of the first embodiment, common components are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 4 shows an example of the configuration of an image forming system 500B according to the second embodiment of the present invention. As illustrated in FIG. 4, the subsequent image forming apparatus 300 includes a control unit 302, an image forming unit 310, a fixing unit 320, a paper feeding unit 330, a temperature sensor unit 340, and a communication unit 350.

  The temperature sensor unit 340 measures the paper temperature T3 of the paper P conveyed from the preceding image forming apparatus 100 to the subsequent image forming apparatus 300 via the intermediate conveying apparatus 200, and uses measurement information DT3 obtained by the measurement. This is supplied to the control unit 302. Assume that the paper P is, for example, a paper that has been fixed by the image forming apparatus 100 in the previous stage and then cooled. The temperature sensor unit 340 constitutes an example of a temperature measurement unit.

  The post-stage control unit 302 acquires the paper temperature T3 of the paper P measured by the temperature sensor unit 340. Then, it is determined whether or not the paper temperature T3 of the paper P is substantially equal to or lower than the target temperature T. When the post-stage control unit 302 determines that the paper temperature T3 of the paper P is substantially equal to the target temperature T, the paper temperature T3 is the paper temperature of the paper P when the image forming apparatus 100 in the front stage is fed. It is determined that the normal range is almost equal to T1. Therefore, in this case, feedback processing to the cooling unit 230 of the intermediate transfer device 200 is not performed.

  On the other hand, when it is determined that the paper temperature T3 of the paper P is higher than the target temperature T despite the cooling process being performed in the intermediate conveyance device 200, the post-stage control unit 302 determines the paper temperature T3 and the target temperature T. In accordance with the temperature difference between them, the stop time for temporarily stopping the paper P in the stacking unit 220 of the intermediate conveyance device 200 is adjusted slightly longer, or the cooling unit 230 is adjusted so that the air blowing amount of the cooling unit 230 becomes slightly stronger. .

  In the above-described example, the feedback process to the cooling unit 230 or the like is performed based on the paper temperature T3 of the paper P conveyed to the subsequent image forming apparatus 300, but the present invention is not limited to this, and the subsequent process is not limited thereto. The internal temperature T4 in the gantry of the image forming apparatus 300 can be measured by the temperature sensor unit 340, and the cooling control of the paper P can be performed based on the internal temperature T4. This is because the internal temperature may change due to the carry-in of the subsequent image forming apparatus 300 of the paper P. In this case as well, the above-described feedback processing can be similarly applied. That is, when the internal temperature T4 is higher than the target temperature T, the sheet temperature T3 of the sheet P fed to the subsequent image forming apparatus 300 is adjusted by adjusting the stacking unit 220 and the cooling unit 230 of the intermediate conveyance device. The target temperature T is set to the target temperature T (paper temperature T1 when the image forming apparatus 100 in the preceding stage is fed).

  In the above-described example, the sheet P conveyed to the subsequent image forming apparatus 300 has been subjected to the cooling process in steps S190 to S230 illustrated in FIG. The paper temperature T3 or the internal temperature T4 of the processed paper P may be measured first, and the conveyance may be temporarily stopped and the cooling control of the cooling unit 230 may be performed based on the paper temperature T3 or the internal temperature T4.

  As described above, according to the second embodiment, based on the paper temperature T3 and the internal temperature T4 of the paper P fed to the subsequent image forming apparatus 300, Since the cooling unit 230 is adjusted by feedback control, the paper temperature of the paper P fed to the subsequent image forming apparatus 300 can be made closer to the target temperature T. As a result, the image quality of the image printed on both sides of the paper P can be improved, and the number of corrections of the subsequent image forming apparatus 300 can be reduced.

  It should be noted that the technical scope of the present invention is not limited to the above-described embodiments, and includes those in which various modifications are made to the above-described embodiments without departing from the spirit of the present invention. In the above-described embodiment, the point that the post-stage control unit 302 controls the temperature of the paper P has been described. However, the present invention is not limited to this, and the pre-stage control unit 102 may control the temperature of the paper P. good. In the above embodiment, the case where the paper P is fed from the paper feeding unit 130 of the preceding image forming apparatus 100 has been described. However, the paper P is fed from the paper feeding unit 430 of the large-capacity paper feeding device 400 to the previous stage. The image forming apparatus 100 may be fed. In this case, the above-described cooling control of the paper P is performed using the paper temperature T5 instead of the paper temperatures T1 and T3 of the paper P. Furthermore, when the paper P is cooled, the cooling of the paper P is performed by the cooling unit 230 after the transport of the paper P is temporarily stopped. However, the cooling unit 230 is being transported without stopping the transport of the paper P. Thus, the sheet P can be cooled.

100 Image forming apparatus 110, 310 in the previous stage Image forming part 120 Fixing part 140, 240, 340, 370 Temperature sensor part 200 Intermediate transport apparatus 240 Cooling part 300 Image forming apparatus 302 in the subsequent stage Image forming system in the subsequent stage 500A, 500B

Claims (9)

A first image forming apparatus comprising: an image forming unit that forms an image on a sheet; and a fixing unit that fixes the image formed by the image forming unit on the sheet;
A tandem including a second image forming apparatus connected in series downstream of the first image forming apparatus and having an image forming unit that forms an image on a sheet discharged from the first image forming apparatus. An image forming system of the type,
A fixing sheet measuring unit that is provided in a conveyance path between the fixing unit of the first image forming apparatus and the second image forming apparatus, and that measures a paper temperature of the sheet discharged from the fixing unit; ,
A cooling unit that is provided in a conveyance path between the fixing unit of the first image forming apparatus and the second image forming apparatus and that cools the sheet discharged from the fixing unit;
Before the paper is carried into the second image forming apparatus based on the paper temperature provided in the first image forming apparatus or the second image forming apparatus and measured by the fixing paper measuring unit. And a control unit that controls the cooling unit so that the paper temperature of the paper becomes a preset target temperature. The first image forming apparatus includes a paper feed unit that feeds paper, and a paper feed paper measurement unit that measures the temperature of the paper fed from the paper feed unit and before passing through the fixing unit,
The control unit sets the paper temperature of the paper measured by the paper feeding paper measurement unit to the target temperature, and the paper temperature of the paper discharged from the fixing unit becomes the target temperature. The image forming system according to claim 1, wherein the cooling unit is controlled. A transport device having a switchback mechanism that reverses the front and back of the paper fixed by the fixing unit of the first image forming apparatus and transports the paper to the second image forming apparatus;
The image forming system according to claim 2, wherein the cooling unit is provided in the switchback mechanism unit of the transport device. The control unit temporarily stops the conveyance of the paper in the switchback mechanism when the paper temperature of the paper measured by the fixing paper measurement unit is higher than the target temperature. Item 4. The image forming system according to Item 3. An ambient temperature measuring unit for measuring ambient temperatures of the first and second image forming apparatuses;
The control unit sets the ambient temperature measured by the ambient temperature measurement unit to the target temperature, and the cooling unit so that the paper temperature of the paper discharged from the fixing unit becomes the target temperature. The image forming system according to any one of claims 1 to 4, wherein the image forming system is controlled. The second image forming apparatus includes a temperature measuring unit that measures a paper temperature of the paper conveyed from the first image forming apparatus or an internal temperature of the second image forming apparatus.
The said control part controls the said cooling part based on the comparison result with the said paper temperature or the said internal temperature of the said sheet | seat of the said temperature measurement part, and the said target temperature. The Claims 1 thru | or 5 characterized by the above-mentioned. The image forming system according to any one of the above. The transport device includes a stack unit that stacks the sheets discharged from the first image forming apparatus,
The image forming system according to claim 3, wherein the cooling unit is provided in the stack unit. The image forming system according to any one of claims 1 to 7, wherein the cooling unit has a decurling function for decurling the paper. The control unit transfers the sheet to the second image forming apparatus when the sheet temperature of the sheet discharged from the fixing unit of the first image forming apparatus becomes equal to or lower than the target temperature. The image forming system according to any one of claims 1 to 8, wherein paper is fed.

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