JP2016157011A - Image forming system, image forming method, and charge adjusting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming system, image forming method, and charge adjusting device that can stably suppress adhesion between sheets on which images are formed.SOLUTION: An image forming system comprises: an image forming part 240 that forms images on sheets P; charge control units 320 and 330 that charge the sheets P on which images are formed by the image forming part 240 in order to suppress adhesion between the sheets; a sheet temperature detection part 350 for detecting the temperature of the sheets P; and an applied current control part 360 that controls a current to be supplied to the charge control units on the basis of the temperature of the sheets P.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an image forming system, an image forming method, and a charge adjusting device.

  When sheets on which images are formed using an electrophotographic process to which toner is applied are stacked in a post-processing device or a stacker device, the sheets may stick to each other due to electrostatic force between the sheets. . Therefore, before the sheets are stacked, the sheets are charged by the charge control unit to suppress sticking between the sheets (for example, see Patent Document 1).

JP 2012-140223 A

  However, since the sheet is conveyed to the charge control unit after pressure and heat are applied and the toner image is melted and fixed, the temperature of the sheet when the sheet is charged by the charge control unit is not constant and varies. Produce. For this reason, even if the current (applied current) supplied to the charge control unit is the same, there is a difference in charging effect (charging performance for suppressing sticking between sheets). Therefore, it is difficult to stably suppress the sticking between sheets.

  The present invention has been made in order to solve the problems associated with the above-described prior art, and provides an image forming system, an image forming method, and a charge adjusting device capable of stably suppressing sticking between sheets on which images are formed. The purpose is to provide.

  The above object of the present invention is achieved by the following means.

An image forming unit for forming an image on paper;
A charge control unit for charging the paper on which an image is formed by the image forming unit in order to suppress sticking between the papers;
A paper temperature detector for detecting the temperature of the paper;
An applied current control unit that controls a current supplied to the charge control unit based on the temperature of the paper;
An image forming system comprising:

  (2) The image forming system according to (1), wherein the sheet temperature detecting unit includes a sheet temperature sensor that measures a temperature of the sheet.

(3) The paper has a first surface on which an image is initially formed, and a second surface on which an image is formed after the image is formed on the first surface,
The image forming system according to (2), wherein the sheet temperature sensor measures a temperature of the first surface of the sheet after an image is formed on the second surface.

(4) A fixing unit that is disposed between the image forming unit and the charge control unit and fixes the toner image by applying pressure and heat to the toner image forming the image on the sheet. ,
A temperature adjusting unit for adjusting the temperature of the paper at the time of fixing,
The fixing unit includes a fixing roller located on a side where a toner image to be fixed on the paper is disposed, and a pressure roller located on the opposite side of the fixing roller through the paper,
The image forming apparatus according to any one of (1) to (3), wherein the temperature adjusting unit includes a heater that heats the pressure roller and a fan that cools the pressure roller. system.

(5) a fixing unit that is disposed between the image forming unit and the charge control unit and fixes the toner image by applying pressure and heat to the toner image forming the image on the paper. And further,
The fixing unit includes a fixing roller located on a side where a toner image to be fixed on the paper is disposed, and a pressure roller located on the opposite side of the fixing roller through the paper,
The paper temperature detection unit has a temperature sensor that measures the temperature of the pressure roller,
The image forming system according to (1), wherein the temperature of the sheet is estimated based on a temperature of the pressure roller.

(6) A fixing unit that is disposed between the image forming unit and the charge control unit and fixes the toner image by applying pressure and heat to the toner image forming the image on the paper. And further,
The fixing unit includes a fixing roller located on a side where a toner image to be fixed on the paper is disposed, and a pressure roller located on the opposite side of the fixing roller through the paper,
The paper temperature detection unit includes a temperature sensor that measures the temperature of the fixing roller and a temperature sensor that measures the temperature of the pressure roller,
The image forming system according to (1), wherein the temperature of the sheet is estimated based on a temperature of the fixing roller and a temperature of the pressure roller.

(7) It further has a temperature adjustment unit for adjusting the temperature of the paper at the time of fixing,
The image forming system according to (5) or (6), wherein the temperature adjustment unit includes a heater that heats the pressure roller and a fan that cools the pressure roller.

  (8) The image forming system according to any one of (1) to (7), wherein the charge control unit includes a charging roller that charges the paper.

(9) It further has a temperature detection unit for detecting the temperature of the charging roller,
The image forming system according to (8), wherein the applied current control unit controls a current supplied to the charge control unit based on a temperature of the sheet and a temperature of the charging roller.

(10) further including a potential detection unit for detecting the surface potential of the paper;
In any one of (1) to (8), the applied current control unit controls a current supplied to the charge control unit based on a temperature of the sheet and the surface potential. The image forming system described.

(11) a paper basis weight detection unit for detecting the basis weight of the paper;
A toner adhesion amount detection unit for detecting the adhesion amount of the toner forming the image,
The applied current control unit controls the current supplied to the charge control unit based on the temperature of the paper, the basis weight, and the adhesion amount of the toner. The image forming system according to any one of the above.

  (12) The image forming apparatus including the image forming unit, the charge control unit, the paper temperature detection unit, and the applied current control unit, wherein any of (1) to (11) is provided The image forming system according to claim 1.

(13) an image forming apparatus including the image forming unit and the paper temperature detecting unit;
A charge adjusting device including the charge control unit and the applied current control unit,
The image forming system according to any one of (1) to (11), wherein the charge adjusting device is connected to the image forming apparatus on a downstream side in a conveyance direction of the sheet. .

(14) When charging the sheet on which the image is formed by the image forming unit by the charge control unit for suppressing the sticking between the sheets on which the image is formed by the image forming unit,
An image forming method, wherein an applied current control unit controls a current supplied to the charge control unit based on a temperature of the sheet.

  (15) The image forming method according to (14), wherein the temperature of the paper is measured by a paper temperature sensor.

(16) The paper has a first surface on which an image is first formed, and a second surface on which an image is formed after the image is formed on the first surface,
The image forming method according to (15), wherein the temperature of the first surface of the paper after the image formation on the second surface is measured by the paper temperature sensor.

(17) A fixing unit that is disposed between the image forming unit and the charge control unit and fixes the toner image by applying pressure and heat to the toner image forming the image on the sheet. A fixing roller located on a side where a toner image to be fixed on the paper is disposed, and a pressure roller located on the opposite side of the fixing roller via the paper,
Any of (14) to (16) above, wherein the temperature of the paper at the time of fixing is adjusted by a temperature adjustment unit having a heater for heating the pressure roller and a fan for cooling the pressure roller. 2. The image forming method according to item 1.

(18) A fixing unit that is arranged between the image forming unit and the charge control unit and fixes the toner image by applying pressure and heat to the toner image forming the image on the paper. A fixing roller located on a side where a toner image to be fixed on the paper is disposed, and a pressure roller located on the opposite side of the fixing roller via the paper,
The image forming method according to (14), wherein the temperature of the sheet is estimated based on a temperature of the pressure roller.

(19) A fixing unit that is arranged between the image forming unit and the charge control unit and fixes the toner image by applying pressure and heat to the toner image forming the image on the paper. A fixing roller located on a side where a toner image to be fixed on the paper is disposed, and a pressure roller located on the opposite side of the fixing roller via the paper,
The image forming method according to (14), wherein the temperature of the sheet is estimated based on a temperature of the fixing roller and a temperature of the pressure roller.

  (20) The temperature of the paper at the time of fixing is adjusted by a temperature adjusting unit having a heater for heating the pressure roller and a fan for cooling the pressure roller. ) Image forming method.

(21) The charge control unit includes a charging roller for charging the paper,
Any one of the above (14) to (20), wherein the applied current control unit controls the current supplied to the charge control unit based on the temperature of the paper and the temperature of the charging roller. The image forming method according to item.

  (22) The applied current control unit controls the current supplied to the charge control unit based on the temperature of the paper and the surface potential of the paper. The image forming method according to any one of the above.

  (23) The applied current control unit controls the current supplied to the charge control unit based on the temperature of the paper, the basis weight of the paper, and the amount of toner that forms the image. The image forming method according to any one of (14) to (20), wherein:

(24) A charge adjusting device connected to the downstream side in the paper transport direction with respect to an image forming apparatus having an image forming unit for forming an image on a paper,
A charge control unit for charging the paper on which an image is formed by the image forming unit in order to suppress sticking between the papers;
A paper temperature detector for detecting the temperature of the paper;
An applied current control unit that controls a current supplied to the charge control unit based on the temperature of the paper;
A charge control device comprising:

  According to the present invention, when the paper is charged by the charge control unit, the current (applied current) supplied to the charge control unit is controlled based on the temperature of the paper, so the temperature of the paper is not constant and varies. Even if this occurs, by supplying an appropriate current to the charge control unit and obtaining a good charging effect (charging performance for suppressing sticking between papers), sticking between papers is stable. Can be suppressed. That is, it is possible to provide an image forming system, an image forming method, and a charge adjusting device that can stably suppress sticking between sheets on which images are formed.

1 is a cross-sectional view for explaining an image forming system according to Embodiment 1. FIG. FIG. 2 is a conceptual diagram for explaining electric charges of a sheet on which an image is formed in the image forming apparatus shown in FIG. 1. It is a conceptual diagram for demonstrating sticking of the paper in which the image was formed. It is a conceptual diagram for demonstrating the electric charge adjustment in the electric charge adjustment apparatus shown by FIG. It is the schematic for demonstrating an electric charge adjustment apparatus. 3 is a flowchart for explaining an image forming method according to the first embodiment. FIG. 10 is a schematic diagram for explaining a first modification of the first embodiment. FIG. 10 is a schematic diagram for explaining a second modification of the first embodiment. FIG. 10 is a schematic diagram for explaining a third modification of the first embodiment. FIG. 10 is a schematic diagram for illustrating a fourth modification of the first embodiment. FIG. 10 is a schematic diagram for illustrating a fifth modification of the first embodiment. FIG. 10 is a schematic diagram for illustrating a sixth modification of the first embodiment. FIG. 6 is a conceptual diagram for explaining an influence of a sheet temperature on a sheet charge. FIG. 5 is a schematic diagram for explaining a charge adjusting device of an image forming system according to a second embodiment. 5 is a flowchart for explaining an image forming method according to a second embodiment. FIG. 10 is a schematic diagram for explaining a first modification of the second embodiment. FIG. 10 is a schematic diagram for explaining a second modification of the second embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the dimension ratio of drawing is exaggerated on account of description, and may differ from an actual ratio.

  FIG. 1 is a cross-sectional view for explaining the image forming system according to the first embodiment, and FIG. 2 is a conceptual diagram for explaining electric charges of a sheet on which an image is formed in the image forming apparatus shown in FIG. FIG. 3 is a conceptual diagram for explaining sticking between sheets on which images are formed, and FIG. 4 is a conceptual diagram for explaining charge adjustment in the charge adjusting device shown in FIG.

  As shown in FIG. 1, the image forming system 100 according to the first embodiment includes an image forming apparatus 200, a charge adjustment apparatus 300, and a stacker apparatus 400 along the paper conveyance direction D.

  The image forming apparatus 200 is used to form an image on a sheet P that is a recording medium, using an electrophotographic process. The electrophotographic process is applied with toner and includes charging, exposure, development, transfer and fixing steps. For example, when images are formed on both sides of the paper P, as shown in FIG. 2, the paper P is charged (charged) by the transfer of toner to the first surface and the transfer of toner to the second surface. . Therefore, as shown in FIG. 3, when the sheets P are stacked, the sheets are attached to each other. The first surface is a surface on which an image is first formed, and the second surface is a surface on which an image is formed after the image is formed on the first surface.

  The charge adjusting device 300 is used to adjust the charge (charged state) of the paper P conveyed from the image forming apparatus 200 and suppress sticking between the papers. For example, as shown in FIG. 4, the charge adjustment device 300 applies a charge opposite in polarity to the charges on the first and second surfaces of the sheet P every other sheet P on which images are formed on both sides. By supplying, the polarities of the charges on the first side and the second side of the paper P are reversed. As a result, when the sheets P are stacked, the electrostatic forces in the repulsive direction act between the sheets P adjacent in the stacking direction, so that the sheets are positively separated from each other. The method of adjusting the charge (charged state) of the paper P is not limited to the above embodiment.

  The stacker device 400 is a post-processing device having a control unit 410 and a paper storage unit 420. The control unit 410 is configured to control the sheet storage unit 420 in accordance with an instruction from the image forming apparatus 200 and to sequentially stack the sheets P conveyed from the charge adjustment apparatus 300.

  Since the charge of the first and second surfaces of the paper P is adjusted by the charge adjusting device 300 every other sheet, and the electrostatic force in the repulsive direction works, sticking between the papers is suppressed, The stacking of the sheets P in the sheet storage unit 420 is executed smoothly. The post-processing apparatus is not limited to a form configured only from the stacker apparatus 400.

  Next, the image forming apparatus 200 will be described in detail.

  The image forming apparatus 200 includes a control unit 210, an operation panel unit 220, an image reading unit 230, an image forming unit 240, a fixing unit 250, a sheet feeding unit 260, a sheet conveyance path 270, a reverse sheet conveyance path 280, and a communication interface 290. .

  The control unit 210 is used to control the entire image forming system 100 and includes a CPU 212 and a storage unit 214.

  The CPU 212 is a control circuit composed of a microprocessor and the like that executes control of each unit and various arithmetic processes according to a program. Each function of the image forming system 100 is exhibited by the CPU 212 executing a corresponding program. Is done.

  The storage unit 214 is used to store various programs and various data, and includes ROM (read only memory), RAM (random access memory), rewritable nonvolatile semiconductor memory (for example, flash memory), a hard disk drive device, and the like. Are appropriately combined. For example, a program stored in the ROM is read by the CPU 212 as necessary, and is executed using the RAM as a work area for temporarily storing the program and data necessary for executing the program.

  The operation panel 220 also serves as a display unit and an input unit, and includes a display unit 222 and a keyboard unit 224. The display unit 222 is used to display a device configuration, a print job progress status, an error occurrence status, a setting that can be changed at present, a warning for alerting the user, and the like. The keyboard unit 224 includes a plurality of keys including a selection key for specifying a paper size, a numeric keypad for setting the number of copies, a start key for instructing start of operation, a stop key for instructing stop of operation, a keyboard for inputting characters, and the like. Have a key. The display unit 222 may be a touch panel configured to be able to input an instruction depending on the position of a finger or pen that has touched.

  The image reading unit 230 includes a scanner having an automatic document feeder (ADF) and a CCD (Charge Coupled Device) image sensor, and is used to read an image of a document and generate image data. The

  The image forming unit 240 is used to print print data stored in the storage unit 214 according to an instruction from the CPU 212 using an electrophotographic process. The image forming unit 240 includes an image forming unit 242, an intermediate transfer belt 244, a primary transfer roller 246, and a secondary transfer roller 248.

  The image forming unit 242 is provided corresponding to each color of yellow (Y), magenta (M), cyan (C), and black (K), and each includes a photosensitive drum, a charger, an exposure device, and a developing device. Has a vessel. The photosensitive drum is an image carrier having a photosensitive layer made of a resin such as polycarbonate including an organic photoconductor (OPC). The charger charges the surface of the photosensitive drum uniformly. The exposure apparatus forms an electrostatic latent image corresponding to the image data on the surface of the uniformly charged photosensitive drum. The developing device develops the electrostatic latent image into a toner image.

  The intermediate transfer belt 244 is an endless belt, is wound around a plurality of rollers, and is supported so as to be able to run. The primary transfer roller 246 is disposed at a position facing the photosensitive drum (image forming unit 242) with the intermediate transfer belt 244 interposed therebetween, and electrostatically attracts the toner image formed on the surface of the photosensitive drum to intermediate transfer belt 246. Used to transfer to 244. Therefore, the toner images of the respective colors formed on the photosensitive drum are sequentially transferred onto the intermediate transfer belt 244, and the toner images (color) in which the layers of the respective colors (Y), (M), (C), and (K) are superimposed. Image) is formed on the intermediate transfer belt 244.

  The secondary transfer roller 248 is used to transfer the toner image formed on the intermediate transfer belt 244 to the paper P. In transferring the toner image, a high positive voltage is applied to the secondary transfer roller 248, so that the negatively charged toner image is electrostatically attracted to the sheet.

  The fixing unit 250 includes a fixing roller 251 and a pressure roller 256. The fixing roller 251 is positioned on the side where the toner image to be fixed on the paper P is disposed, and has a heater 252 for applying heat to the paper P. The pressure roller 256 is positioned on the opposite side of the fixing roller 251 via the paper P, and is elastically biased to apply pressure to the paper P. When the toner image transferred onto the paper P passes between the fixing roller 251 and the pressure roller 256, pressure and heat are applied to melt and fix the toner image. The fixing roller 251 can also be configured by a plurality of rollers having a roller having a heater and a roller not having a heater.

  The paper feeding unit 260 is used to store paper P on which an image is formed. For example, the paper feeding cassettes 262 and 266 having two detachable configurations and the papers stored in the paper feeding cassettes 262 and 266 are used. And rolling rollers 264 and 268 for taking out P one by one.

  The paper transport path 270 is used to transport the paper P stored in the paper feed cassettes 262 and 266 to the charge adjustment device 300 via the inside of the image forming apparatus 200, and includes a registration roller 272 and an intermediate transport roller. 274 and a paper discharge roller 276.

  The registration roller 272 and the intermediate transport roller 274 are disposed between the paper feed cassettes 262 and 266 and the image forming unit 240, transport the paper P taken out from the paper feed cassettes 262 and 266 one by one, and the intermediate transfer belt. It is configured to pass between 244 and the secondary transfer roller 248. The paper discharge roller 276 is disposed downstream of the fixing unit 250 in the paper conveyance direction D, and is configured to discharge the paper P that has passed through the fixing unit 250 from the image forming apparatus 200 and to convey it to the charge adjustment apparatus 300. ing.

  The reverse paper conveyance path 280 communicates between the paper conveyance path 270 between the paper discharge roller 276 and the fixing unit 250 and the paper conveyance path 270 between the registration roller 272 and the intermediate conveyance roller 274. The sheet P is configured to be used for reversing and discharging the sheet P or forming images on both sides of the sheet P. The reverse paper conveyance path 280 includes a switching gate 282, a reverse roller 284, a re-introducing roller 286, and a reverse conveyance roller 288.

  The switching gate 282 is disposed between the paper discharge roller 276 and the fixing unit 250 and is used to branch the reverse paper conveyance path 280 from the paper conveyance path 270. The reversing roller 284 is used for reversing and temporarily holding the front and back of the sheet P conveyed via the switching gate 282. The re-introducing roller 286 is configured to transport the held paper P whose front and back are reversed to a paper transport path 270 between the registration roller 272 and the intermediate transport roller 274. The reverse conveyance roller 288 is disposed between the switching gate 282 and the reverse roller 284 and conveys the held paper P whose front and back are reversed to the paper discharge roller 276 side via the switching gate 282. Used for.

  The communication interface 290 is an expansion device including a so-called LAN board, and is used to add a communication function for executing data transmission / reception via the network to the image forming apparatus 200. The received data is, for example, a print job. The network is a local area network (LAN) that connects computers and network devices according to standards such as Ethernet (registered trademark), token ring, and FDDI (Fiber-Distributed Data Interface), and LANs are dedicated to each other. It consists of various networks such as a wide area information communication network (WAN) connected by a line, the Internet, and combinations thereof. The network protocol is, for example, TCP / IP (Transmission Control Protocol / Internet Protocol).

  When the image forming apparatus 200 is dedicated to printing, the image reading unit 230 can be omitted as appropriate. The image forming unit 240 is not limited to a tandem type having a plurality of image forming units 242, and a rotary type using a single image forming unit can also be applied.

  Next, the charge adjusting device 300 will be described in detail.

  FIG. 5 is a side view for explaining the charge adjusting device.

  As shown in FIGS. 1 and 5, the charge adjustment device 300 includes a control unit 310, charge control units 320 and 330, a sheet temperature sensor 350, a charge adjustment power supply 360, and a paper discharge roller 390. The paper discharge roller 390 is configured to discharge the paper P from the charge adjustment device 300 and transport it to the stacker device 400 (see FIG. 1).

  The control unit 310 is used to control each unit of the charge adjustment device 300 in accordance with an instruction from the control unit 210 of the image forming apparatus 200 (see FIG. 1), and based on the temperature of the paper P, as will be described later, An applied current control unit that controls the current supplied to the control units 320 and 330 is configured.

  The charge control units 320 and 330 are used to charge the paper P on which an image is formed by the image forming unit 240 in order to suppress sticking between the papers, and from the first charging roller 320 and the second charging roller 330. Composed.

  The first charging roller 320 is made of a conductive rubber roller and is driven to rotate by a motor (not shown). Both ends of the rotation shaft 322 of the first charging roller 320 are rotatably supported by the bearing portion 326, and the bearing portion 326 is in contact therewith. The bearing portion 326 has conductivity.

  The second charging roller 330 is composed of a conductive rubber roller, and is disposed to face the first charging roller 320 and is configured to be rotatable. Both ends of the rotation shaft 332 of the second charging roller 330 are rotatably supported by the bearing portion 336, and the bearing portion 336 is in contact therewith. The bearing portion 336 has conductivity. The second charging roller 330 is elastically biased so that the paper P can pass through the nip 340 between the first charging roller 320 and the second charging roller 330.

  The paper temperature sensor 350 is a paper temperature detection unit for detecting the temperature of the paper P, and is disposed in the vicinity of the second charging roller 330, measures the temperature of the back surface of the paper P, and sends the result to the control unit 310. Configured to send. Note that the back surface of the paper P is the surface (first surface) on which the image is first formed when images are formed on both surfaces of the paper P. When the image is formed on only one surface of the paper P, the image is formed. It is an unfinished surface.

  If necessary, the paper temperature sensor 350 may be arranged in the vicinity of the first charging roller 320 instead of being arranged in the vicinity of the second charging roller 330 to measure the temperature of the surface of the paper P. In addition to being arranged in the vicinity of the charging roller 330, it may be arranged in the vicinity of the first charging roller 320, and the temperature of both surfaces of the paper P may be measured. The surface of the paper P is the surface (second surface) on which the image is formed after forming the image on the first surface when forming images on both sides of the paper P, and the image is formed only on one side of the paper P. In this case, it is a surface (first surface) on which an image is first formed.

  The charge adjustment power supply 360 is a direct current (DC) power supply, and is electrically connected to the charge control units 320 and 330 via the bearing portion 326 and the bearing portion 336, and a current (applied to the charge control units 320 and 330 is applied. It is possible to apply a voltage by supplying a current. Accordingly, the charge control units 320 and 330 can adjust the charge by charging the paper P passing through the nip 340.

  For example, every other sheet of paper P on which images are formed on both sides by the charge adjustment power supply 360 (charge control units 320 and 330), the charge having the opposite polarity to the charges on the first and second sides of the sheet P , And when reversing the polarities of the charges on the first and second surfaces of the paper P, when the paper P is stacked, electrostatic forces in a direction repelling each other between the adjacent papers P in the stacking direction work. The sheets are actively separated from each other (see FIG. 4). Note that the charge adjustment power supply 360 can be configured to superimpose alternating current (AC) as necessary.

  On the other hand, the sheet P is conveyed to the nip 340 of the charge control units 320 and 330 after the toner image is melted and fixed in the fixing unit 250 by applying pressure and heat. The temperature of the paper P when charging the paper P is not constant and varies.

  Since the electric resistance of the toner layer varies depending on the temperature of the paper P, when a constant current is supplied to the charge control units 320 and 330, there is a difference in charging effect (charging performance for suppressing sticking between papers). It is difficult to stably suppress the occurrence of sticking between sheets.

  Therefore, the control unit 310 controls the charge adjustment power source 360 based on the temperature of the paper P measured by the paper temperature sensor 350 and has a good charging effect (charging performance for suppressing sticking between papers). Is supplied to the charge control units 320 and 330. For example, the current (applied current) is controlled to decrease when the temperature of the paper P is high, and is controlled to increase when the temperature of the paper P is low.

  In the image forming system 100, as described above, even when the temperature of the paper P is not constant and varies, an appropriate current is supplied to the charge control units 320 and 330, and a good charging effect (paper) By obtaining the charging performance for suppressing sticking between the sheets, sticking between the sheets can be stably suppressed.

  Next, an image forming method according to Embodiment 1 will be described.

  FIG. 6 is a flowchart for explaining the image forming method according to the first embodiment. Note that the algorithm shown in the flowchart shown in FIG. 6 is stored as a program in the storage unit 214 of the control unit 210 of the image forming apparatus 200 and is executed by the CPU 212.

  First, it is determined whether there is an instruction to start a print job (step S10). When it is determined that the start of the print job has been instructed (step S10: YES), the sheets P on which images are to be formed are taken out from the sheet feeding unit 260 one by one, and the image forming unit passes through the sheet conveyance path 270. It is conveyed toward 240 (step S11). The toner image is transferred by the image forming unit 240 to the first surface located on the surface of the paper P (step S12), and the toner image is melted and fixed by the fixing unit 250 (step S13).

  Then, it is determined whether or not the sheet P is printed on both sides (whether an image is formed on the second side located on the back side of the sheet P) (step S14). When it is determined that the paper P is not printed on both sides (step S14: NO), the process proceeds to step S23.

  If it is determined that the paper P is printed on both sides (step S14: YES), the front and back of the paper P are reversed in the reverse paper conveyance path 280 (step S15). Thus, the first surface of the paper P becomes the back surface, and the second surface of the paper P becomes the front surface. Thereafter, the paper is transported and introduced into the paper transport path 270 (step S16). The introduction position is a sheet conveyance path 270 between the registration roller 272 adjacent to the fixing unit 250 and the intermediate conveyance roller 274.

  The toner image is transferred by the image forming unit 240 to the second surface located on the surface of the paper P (step S17), and the toner image is melted and fixed by the fixing unit 250 (step S18).

  When the paper P is conveyed from the image forming apparatus 200 to the charge adjustment device 300, the temperature of the first surface located on the back surface of the paper P is measured by a paper temperature sensor 350 disposed in the vicinity of the second charging roller 330. (Step S19). Based on the measured temperature of the paper P, an appropriate current (applied current) that provides a good charging effect (charging performance for suppressing sticking between papers) is determined (step S20). Then, the determined current is supplied (applied) to the charge control units 320 and 330 from the charge adjustment power supply 360 controlled by the control unit 310 (step S21), thereby the nip 340 of the charge control units 320 and 330. The sheet P passing through is charged (step S22), and the process proceeds to step S23.

  In step S <b> 23, the paper P is discharged from the charge adjustment device 300 toward the stacker device 400 by the paper discharge roller 390. Then, the paper P is sequentially stacked on the paper storage unit 420 of the stacker device 400 (step S24). Since the paper P is adjusted in electric charge and has a good charging effect (charging performance for suppressing sticking between papers), sticking between the papers is suppressed, and the paper P in the paper storage unit 420 is suppressed. Stacking is performed smoothly.

  Thereafter, it is determined whether or not the print job is completed (step S25). If it is determined that the print job is complete (step S25: YES), the process ends. If it is determined that the print job is incomplete (step S25: NO), the process proceeds to step S11.

  In this image forming method, as described above, even when the temperature of the paper P is not constant and variation occurs, an appropriate current is supplied to the charge control units 320 and 330, and a good charging effect (paper) By obtaining the charging performance for suppressing sticking between the sheets, sticking between the sheets can be stably suppressed.

  Next, modified examples 1 to 6 of the first embodiment will be sequentially described.

  FIG. 7 is a schematic diagram for explaining a first modification of the first embodiment.

  The charge control unit is not limited to the form in contact with the paper P, and may be configured by the first electrode 320A and the second electrode 330A that are not in contact with the paper P, as shown in FIG. In this case, the first electrode 320A and the second electrode 330A are disposed so as to form a gap 340A through which the paper P can pass, and current (applied current) is supplied from the charge adjustment power supply 360. Is configured to discharge. Therefore, the first electrode 320A and the second electrode 330A can adjust the charge by charging the paper P passing through the gap 340A.

  FIG. 8 is a schematic diagram for explaining a second modification of the first embodiment.

  The sheet temperature sensor 350 is not limited to the form arranged in the charge adjustment device 300, and can be arranged in the image forming apparatus 200. For example, the arrangement position of the paper temperature sensor 350 is in the vicinity of the paper discharge roller 276 of the image forming apparatus 200.

  FIG. 9 is a schematic diagram for explaining a third modification of the first embodiment.

  The determination of the current (applied current) is not limited to the form executed by the control unit 310, and can also be executed by the control unit 210 of the image forming apparatus 200. In this case, for example, as shown in FIG. 9, the measurement result of the paper temperature sensor 350 is transmitted to the control unit 310, and the current (applied current) determined by the control unit 310 is the control unit of the image forming apparatus 200. 210.

  10 and 11 are schematic diagrams for explaining the fourth and fifth modifications of the first embodiment.

  The current (applied current) supplied to the first charging roller 320 and the second charging roller 330 is not limited to the form of controlling based only on the temperature of the paper P.

  For example, as shown in FIG. 10, temperature detection units 370 and 372 that detect the temperatures of the first charging roller 320 and the second charging roller 330 are arranged, the temperature of the paper P, the temperature of the first charging roller 320, and It is also possible to control the current (applied current) based on the temperature of the second charging roller 330. Further, as shown in FIG. 11, it is possible to arrange a potential detection unit 374 that detects the surface potential of the paper P, and to control the current (applied current) based on the temperature and the surface potential of the paper P. .

  It is also preferable to consider the basis weight of the paper P that affects the temperature of the paper P and the amount of toner adhesion that affects the electrical resistance of the toner layer. That is, the current (applied current) can be controlled based on the temperature, basis weight, and toner adhesion amount of the paper P. The basis weight of the paper P is calculated from the specification data of the paper P stored in the paper feed cassettes 262 and 266, for example. For example, the toner adhesion amount is calculated based on image data formed on the paper P.

  FIG. 12 is a conceptual diagram for explaining the sixth modification of the first embodiment, and FIG. 13 is a conceptual diagram for explaining the influence of the sheet temperature on the sheet charge.

  The surface potential of the paper P has a relationship with the temperature of the paper P at the time of fixing. For example, when fixing the second side in double-sided printing, as shown in FIG. 13, when the temperature of the second side of the paper P is high, the electric resistance of the toner layer is low, so that the charge due to transfer is reduced on the second side. When the temperature of the second surface of the paper P is low, canceling with the charge of the toner, the electric resistance of the toner layer on the first surface is lowered, and much of the charge due to the transfer is not canceled and remains. That is, the electrical resistance of the toner varies depending on the temperature of the paper P, and a difference occurs in the surface potential of the paper P after fixing.

  Therefore, it is preferable that the image forming apparatus 200 includes a temperature adjustment unit that adjusts the temperature of the paper P at the time of fixing so that a difference in the surface potential of the paper P after the fixing does not occur. As shown in FIG. 12, the temperature adjustment unit includes a heater 257, a fan 258, and temperature sensors 352 and 354. The heater 257 is used to heat the pressure roller 256. The fan 258 is used to cool the pressure roller 256. The temperature sensors 352 and 354 are used to measure the temperature of the fixing roller 251 and the temperature of the pressure roller 256, respectively.

  The heaters 252 and 257, the fan 258, and the temperature sensors 352 and 354 are connected to the control unit 210 of the image forming apparatus 200. Therefore, the control unit 210 controls the heater 257 for the pressure roller 256 and the fan 258 based on the measurement results of the temperature sensors 352 and 354 so that no difference occurs in the surface potential of the paper P after fixing. The temperature of the paper P can be adjusted.

  As described above, in Embodiment 1, when charging a sheet by the charge control unit, the current (applied current) supplied to the charge control unit is controlled based on the measured temperature of the sheet. Even if the temperature is not constant and varies, by supplying an appropriate current to the charge control unit and obtaining a good charging effect (charging performance for suppressing sticking between sheets), Sticking between sheets can be stably suppressed. That is, it is possible to provide an image forming system, an image forming method, and a charge adjusting device that can stably suppress sticking between sheets on which images are formed.

  Next, a second embodiment will be described. In addition, about the member which has the same function as Embodiment 1, the same code | symbol is used and in order to avoid duplication, the description is abbreviate | omitted suitably.

  FIG. 14 is a schematic diagram for explaining the charge adjusting device of the image forming system according to the second embodiment.

  The image forming system according to the second embodiment is generally different from the image forming system according to the first embodiment regarding the configuration for detecting the temperature of the paper P, and has temperature sensors 356 and 358 as shown in FIG.

  The temperature sensors 356 and 358 are used to measure the temperature of the fixing roller 251 and the temperature of the pressure roller 256, respectively, and are connected to the control unit 310 of the charge adjusting device 300. The control unit 310 is configured to estimate the temperature of the paper P based on the temperature of the fixing roller 251 and the temperature of the pressure roller 256.

  That is, the temperature sensors 356 and 358 constitute a paper temperature detection unit, and the image forming system according to the second embodiment is supplied to the charge control units 320 and 330 based on the estimated temperature of the paper P. Current (applied current) can be controlled.

  Next, an image forming method according to the second embodiment will be described.

  FIG. 15 is a flowchart for explaining the image forming method according to the second embodiment. The algorithm shown in the flowchart shown in FIG. 15 is stored as a program in the storage unit 214 of the control unit 210 of the image forming apparatus 200 and is executed by the CPU 212.

  The image forming method according to the second embodiment is generally different from the image forming method according to the first embodiment with respect to a method for detecting the temperature of the paper P.

  For example, as shown in FIG. 15, the temperature sensors 356 and 358 measure the temperature of the fixing roller 251 and the temperature of the pressure roller 256 in step S59, and based on the estimated temperature of the paper P in step S60. The current (applied current) supplied to the charge control units 320 and 330 is determined.

  Therefore, in the image forming method according to the second embodiment, the current (applied current) supplied to the charge control unit can be controlled without directly measuring the temperature of the paper P. Note that steps S50 to 58 and S61 to 65 are substantially the same as steps S10 to 18 and S21 to 25 according to the image forming method according to the first embodiment, and a description thereof will be omitted to avoid duplication.

  Next, Modification 1 and Modification 2 of Embodiment 2 will be described sequentially.

  FIG. 16 is a schematic diagram for explaining a first modification of the second embodiment.

  The estimation of the temperature of the paper P is not limited to the form based on the temperature of the fixing roller 251 and the temperature of the pressure roller 256, and based on only the temperature of the pressure roller 256 as shown in FIG. 16, if necessary. Is also possible.

  FIG. 17 is a schematic diagram for explaining a second modification of the second embodiment.

  Also in the second embodiment, it is preferable to have a temperature adjustment unit that adjusts the temperature of the paper P at the time of fixing so that there is no difference in the surface potential of the paper P after the fixing.

  As shown in FIG. 17, the temperature adjustment unit includes a heater 257, a fan 258, and temperature sensors 356 and 358. The heater 257 is used to heat the pressure roller 256. The fan 258 is used to cool the pressure roller 256. The temperature sensors 356 and 358 are used to measure the temperature of the fixing roller 251 and the temperature of the pressure roller 256, respectively.

  The heaters 252 and 257, the fan 258, and the temperature sensors 356 and 358 are connected to the control unit 210 of the image forming apparatus 200. Therefore, the control unit 210 controls the heater 257 and the fan 258 for the pressure roller 256 based on the measurement results of the temperature sensors 356 and 358 so that no difference occurs in the surface potential of the paper P after fixing. The temperature of the paper P can be adjusted.

  The temperature sensors 356 and 358 are also connected to the control unit 310 of the charge adjustment device 300, and the control unit 310 estimates the temperature of the paper P based on the temperature of the fixing roller 251 and the temperature of the pressure roller 256. Used for. That is, the temperature sensors 356 and 358 also serve as a paper temperature detection unit.

  When the measurement data from the temperature sensors 356 and 358 are transmitted to the control unit 310 of the charge adjustment device 300 via the control unit 210 of the image forming apparatus 200, the temperature sensors 356 and 358 are transmitted to the control unit 310 of the charge adjustment device 300. It is not necessary to connect. In addition, if necessary, the temperature sensors constituting the paper temperature detecting unit can be provided independently without using the temperature sensors 356 and 358 as the paper temperature detecting unit.

  As described above, in the second embodiment, the current (applied current) supplied to the charge control unit can be controlled without directly measuring the sheet temperature.

  It should be noted that Modification 1, Modification 3, Modification 4, and Modification 5 of Embodiment 1 can be appropriately combined with Embodiment 2. Also in the second embodiment, it is possible to consider the basis weight of the paper P that affects the temperature of the paper P, and the amount of toner that affects the electrical resistance of the toner layer.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims. For example, the charge adjustment device is built in the image forming apparatus by arranging the charge adjustment device in the paper conveyance path between the switching gate and the discharge roller, or by combining the discharge roller with the charging roller (integrated) It is also possible to The charge control device can also be configured to operate independently.

  The means, method, and program according to the present invention can also be realized by a dedicated hardware circuit. When the present invention is realized by a program, the program is provided by a computer-readable recording medium such as a USB (Universal Serial Bus) memory or a DVD (Digital Versatile Disc) -ROM (Read Only Memory), or a recording medium. Regardless, it may be provided online via a network such as the Internet. In this case, the program is usually transmitted to and stored in a storage device such as a magnetic disk device. The program can be provided as a single application software, or can be provided as a function incorporated in another software.

100 image forming system,
200 image forming apparatus,
210 control unit,
212 CPU,
214 storage unit,
220 operation panel section,
222 display unit,
224 keyboard part,
230 Image reading unit,
240 image forming unit,
242 Imaging unit,
244 Intermediate transfer belt,
246 primary transfer roller,
248 Secondary transfer roller,
250 fixing section,
251 fixing roller,
252 heater,
256 pressure roller,
257 heater,
258 fans,
260 paper feeder,
262,266 paper feed cassette,
264,268 thatched roller,
270 paper transport path,
272 registration rollers,
274 Intermediate transport roller,
276 paper discharge roller,
280 reverse paper transport path,
282 switching gate,
284 reversing roller,
286 Re-loading roller,
288 reverse conveying roller,
290 communication interface,
300 charge control device,
310 control unit (applied current control unit),
320 first charging roller (charge control unit),
320A first electrode (charge control unit),
322 axis of rotation,
326 bearing,
330 Second charging roller (charge control unit),
330A first electrode (charge control unit),
332 axis of rotation,
336 bearing,
340 nip,
340A gap,
350 Paper temperature sensor (paper temperature detector),
352,354 temperature sensor,
356, 358 Temperature sensor (paper temperature detector),
360 power supply for charge adjustment,
370, 372 temperature detector,
374 potential detector,
390 paper discharge roller,
400 stacker device,
410 control unit,
420 paper container,
D paper transport direction,
P paper.

Claims (24)

An image forming unit for forming an image on paper;
A charge control unit for charging the paper on which an image is formed by the image forming unit in order to suppress sticking between the papers;
A paper temperature detector for detecting the temperature of the paper;
An applied current control unit that controls a current supplied to the charge control unit based on the temperature of the paper;
An image forming system comprising:   The image forming system according to claim 1, wherein the sheet temperature detection unit includes a sheet temperature sensor that measures a temperature of the sheet. The paper has a first surface on which an image is first formed, and a second surface on which an image is formed after the image is formed on the first surface;
The image forming system according to claim 2, wherein the paper temperature sensor measures a temperature of the first surface of the paper after an image is formed on the second surface. A fixing unit that is disposed between the image forming unit and the charge control unit and fixes the toner image by applying pressure and heat to the toner image forming the image on the paper;
A temperature adjusting unit for adjusting the temperature of the paper at the time of fixing,
The fixing unit includes a fixing roller located on a side where a toner image to be fixed on the paper is disposed, and a pressure roller located on the opposite side of the fixing roller through the paper,
The image forming system according to claim 1, wherein the temperature adjustment unit includes a heater that heats the pressure roller and a fan that cools the pressure roller. There is further provided a fixing unit that is arranged between the image forming unit and the charge control unit and fixes the toner image by applying pressure and heat to the toner image forming the image on the paper. And
The fixing unit includes a fixing roller located on a side where a toner image to be fixed on the paper is disposed, and a pressure roller located on the opposite side of the fixing roller through the paper,
The paper temperature detection unit has a temperature sensor that measures the temperature of the pressure roller,
The image forming system according to claim 1, wherein the temperature of the sheet is estimated based on a temperature of the pressure roller. There is further provided a fixing unit that is arranged between the image forming unit and the charge control unit and fixes the toner image by applying pressure and heat to the toner image forming the image on the paper. And
The fixing unit includes a fixing roller located on a side where a toner image to be fixed on the paper is disposed, and a pressure roller located on the opposite side of the fixing roller through the paper,
The paper temperature detection unit includes a temperature sensor that measures the temperature of the fixing roller and a temperature sensor that measures the temperature of the pressure roller,
The image forming system according to claim 1, wherein the temperature of the sheet is estimated based on a temperature of the fixing roller and a temperature of the pressure roller. A temperature adjusting unit for adjusting the temperature of the paper at the time of fixing;
The image forming system according to claim 5, wherein the temperature adjustment unit includes a heater that heats the pressure roller and a fan that cools the pressure roller.   The image forming system according to claim 1, wherein the charge control unit includes a charging roller that charges the paper. A temperature detection unit for detecting the temperature of the charging roller;
The image forming system according to claim 8, wherein the applied current control unit controls a current supplied to the charge control unit based on a temperature of the sheet and a temperature of the charging roller. A potential detector for detecting a surface potential of the paper;
The image according to claim 1, wherein the applied current control unit controls a current supplied to the charge control unit based on a temperature of the paper and the surface potential. Forming system.   The applied current control unit controls a current supplied to the charge control unit based on a temperature of the paper, a basis weight of the paper, and an adhesion amount of toner forming the image. The image forming system according to claim 1.   12. The image forming apparatus according to claim 1, further comprising: an image forming apparatus including the image forming unit, the charge control unit, the paper temperature detection unit, and the applied current control unit. Image forming system. An image forming apparatus comprising the image forming unit and the paper temperature detecting unit;
A charge adjusting device including the charge control unit and the applied current control unit,
The image forming system according to claim 1, wherein the charge adjusting device is connected to the image forming apparatus on a downstream side in a conveyance direction of the sheet. When charging the sheet on which the image is formed by the image forming unit by the charge control unit for suppressing the sticking between the sheets on which the image is formed by the image forming unit,
An image forming method, wherein an applied current control unit controls a current supplied to the charge control unit based on a temperature of the sheet.   The image forming method according to claim 14, wherein the temperature of the paper is measured by a paper temperature sensor. The paper has a first surface on which an image is first formed, and a second surface on which an image is formed after the image is formed on the first surface;
The image forming method according to claim 15, wherein the temperature of the first surface of the paper after the image formation on the second surface is measured by the paper temperature sensor. The fixing unit, which is disposed between the image forming unit and the charge control unit and fixes the toner image by applying pressure and heat to the toner image forming the image on the paper, A fixing roller located on the side where the toner image to be fixed is disposed, and a pressure roller located on the opposite side of the fixing roller through the paper,
The temperature of the paper at the time of fixing is adjusted by a temperature adjustment unit having a heater for heating the pressure roller and a fan for cooling the pressure roller. The image forming method according to the description. The fixing unit, which is disposed between the image forming unit and the charge control unit and fixes the toner image by applying pressure and heat to the toner image forming the image on the paper, A fixing roller located on the side where the toner image to be fixed is disposed, and a pressure roller located on the opposite side of the fixing roller through the paper,
The image forming method according to claim 14, wherein the temperature of the sheet is estimated based on a temperature of the pressure roller. The fixing unit, which is disposed between the image forming unit and the charge control unit and fixes the toner image by applying pressure and heat to the toner image forming the image on the paper, A fixing roller located on the side where the toner image to be fixed is disposed, and a pressure roller located on the opposite side of the fixing roller through the paper,
The image forming method according to claim 14, wherein the temperature of the sheet is estimated based on a temperature of the fixing roller and a temperature of the pressure roller.   20. The image according to claim 18, wherein the temperature of the sheet at the time of fixing is adjusted by a temperature adjustment unit having a heater for heating the pressure roller and a fan for cooling the pressure roller. Forming method. The charge control unit has a charging roller for charging the paper,
The current applied to the charge control unit is controlled by the applied current control unit based on the temperature of the paper and the temperature of the charging roller. Image forming method.   21. The current supplied to the charge control unit is controlled by the applied current control unit based on a temperature of the paper and a surface potential of the paper. Image forming method.   The applied current control unit controls a current supplied to the charge control unit based on a temperature of the paper, a basis weight of the paper, and an adhesion amount of toner forming the image. The image forming method according to any one of claims 14 to 20. A charge adjusting device connected to the downstream side in the paper transport direction with respect to an image forming apparatus having an image forming unit for forming an image on paper,
A charge control unit for charging the paper on which an image is formed by the image forming unit in order to suppress sticking between the papers;
A paper temperature detector for detecting the temperature of the paper;
An applied current control unit that controls a current supplied to the charge control unit based on the temperature of the paper;
A charge control device comprising: