Image forming apparatus

Abstract

To suppress decrease in the number of sheets that can be printed by a photoreceptor.SOLUTION: An image forming apparatus comprises: image forming means having a photoreceptor and a driving source which rotationally drives the photoreceptor; control means to control the driving source; and feeding means. When executing a job to form images on more sheets than a prescribed number of sheets, the control means stops feeding operation by the feeding means after the prescribed number of sheets have been fed, executes adjustment operation to adjust conditions relating to feeding of the sheets, and resumes the feeding operation after executing the adjustment operation. When executing the adjustment operation, the control means stops the rotation of the photoreceptor or executes a mode in which it changes a rotational speed of the photoreceptor from a first speed, which is used while the image forming means forms the image on the sheet, to a second speed which is slower than the first speed.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus for forming an image on a sheet. [Background technology]

[0002] Patent Document 1 describes a paper feeder equipped with a side guide plate that determines the position of one side of the paper and a small blower that is attached to the side guide plate and blows air into the edge of the paper. Patent Document 2 describes a blowing operation performed by an air handling unit, and after the blowing operation is stopped, a feeding operation is performed by a sheet feeding unit with the blowing operation stopped. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 04-023747 [Patent Document 2] JP 2023-102814 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the configuration of Patent Document 2, if the photosensitive drum continues to rotate during a period in which a job for forming an image on multiple sheets is being executed and the feeding operation is stopped for the spraying operation, the amount of wear on the photosensitive drum increases relative to the cumulative number of printed sheets. As a result, the number of printable sheets on the photosensitive drum may decrease. In other words, in an image forming device that performs an adjustment operation during the execution of a job, it is required to suppress the decrease in the number of printable sheets on the photosensitive drum.

[0005] SUMMARY OF THE PRESENT DISCLOSURE In view of the above, an object of the present invention is to provide an image forming apparatus capable of suppressing a decrease in the number of printable sheets per photoconductor. [Means for solving the problem]

[0006] One aspect of the present invention is an image forming apparatus comprising: an image forming means having a photosensitive member and a drive source for rotating the photosensitive member and forming an image on a sheet using the photosensitive member; a control means for controlling the drive source; and a feeding means for performing a feeding operation to feed one sheet toward the image forming means, wherein the control means is configured to, when executing a job for forming images on more than a predetermined number of sheets, stop the feeding operation after the predetermined number of sheets have been fed by the feeding means, perform an adjustment operation to adjust conditions related to the feeding of the sheets, and resume the feeding operation after performing the adjustment operation, and wherein, when performing the adjustment operation, the control means stops the rotation of the photosensitive member or executes a mode in which the rotation speed of the photosensitive member is changed from a first speed, which is the rotation speed of the photosensitive member when the image forming means forms an image on a sheet, to a second speed slower than the first speed.

[0007] One aspect of the present invention is an image forming apparatus comprising: a photosensitive member, a charging means for charging the surface of the photosensitive member, and a voltage application means for applying a voltage to the charging means, and an image forming means for forming an image on a sheet using the photosensitive member; a control means for controlling the voltage application means; and a feeding means for performing a feeding operation to feed one sheet toward the image forming means, wherein the control means is configured to, when executing a job for forming images on more than a predetermined number of sheets, stop the feeding operation after the predetermined number of sheets have been fed by the feeding means, perform an adjustment operation to adjust conditions related to the feeding of the sheets, and resume the feeding operation after performing the adjustment operation, and when executing the adjustment operation, the control means stops the application of voltage to the charging means by the voltage application means, or executes a mode in which the voltage applied by the voltage application means to the charging means is changed from a first voltage value, which is the value of the voltage applied by the voltage application means to the charging means when the image forming means forms an image on the sheet, to a second voltage value lower than the first voltage value. Effect of the Invention

[0008] According to the present invention, it is possible to provide an image forming apparatus capable of suppressing a decrease in the number of printable sheets of a photoconductor. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic diagram of an image forming apparatus according to an embodiment. [Diagram 2] FIG. 2 is a block diagram showing a control system of the image forming apparatus according to the embodiment. [Diagram 3] FIG. 2 is a schematic diagram showing an extended feeding device according to an embodiment. [Figure 4] FIG. 2 is a schematic diagram showing an extended feeding device according to an embodiment. [Diagram 5] 4 is a flowchart showing a print job control method according to the embodiment. [Figure 6] FIG. 4 is a diagram showing the relationship between environmental conditions and air blowing time in Example 1. [Figure 7] 5 is a flowchart showing a method for controlling a print job in the first embodiment. [Figure 8] 4 is a sequence chart showing an operation state of the image forming apparatus in the first embodiment. [Figure 9] 5 is a flowchart showing a method for controlling a print job in the first embodiment. [Figure 10] 4 is a sequence chart showing an operation state of the image forming apparatus in the first embodiment. [Figure 11] Graph (a) shows the relationship between the length of air blowing time and the rate of decline in the number of printable sheets on a photosensitive drum, and graph (b) shows the relationship between the length of air blowing time and the rate of decline in productivity of an image forming apparatus. [Figure 12] 10 is a flowchart showing a print job control method in the second embodiment. [Figure 13] 10 is a sequence chart showing an operation state of an image forming apparatus according to a second embodiment. [Figure 14] 11 is a flowchart showing a print job control method according to the third embodiment. [Figure 15] 10 is a sequence chart showing an operation state of an image forming apparatus according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0011] Fig. 1 is a diagram showing a schematic configuration of an image forming apparatus 200 according to an embodiment. The image forming apparatus 200 includes a printer 201 as a main body of the image forming apparatus, and an extended feeding device 500 connected to the printer 201. The extended feeding device 500 is connected to the right side of the printer 201 in Fig. 1, and is configured to be able to feed a sheet S to the printer 201.

[0012] Image forming apparatus 200 is a system (image forming system) including printer 201 that can be used alone as an image forming apparatus, and extended feeding device 500 as an optional device connected to printer 201. Image forming apparatus 200 may include optional devices other than extended feeding device 500. Examples of such optional devices include a sheet processing device (finisher) that performs processing such as binding on sheets on which images have been formed by printer 201, and a large-capacity stacker that can stack a large amount of printed products.

[0013] (Image forming device) As shown in FIG. 1, the printer 201 includes a printer body 201A, an image reading device 202, and an operation unit 730. The printer body 201A has an image forming unit 201B as an image forming means. The image reading device 202 is installed above the printer body 201A in a substantially horizontal position. An ejection space V for ejecting sheets is formed between the image reading device 202 and the printer body 201A. The operation unit 730 is disposed above the printer body 201A and on the front side of the image reading device 202. The operation unit 730 is a user interface of the image forming device 200, and has a display unit such as a touch panel capable of displaying a screen, and an input unit such as a numeric keypad and a print execution button.

[0014] The image forming section 201B of this embodiment is an intermediate transfer type tandem type electrophotographic mechanism. In other words, the image forming section 201B is of a four-drum full-color type. The image forming section 201B includes an exposure device 210 and four process cartridges 211Y, 211M, 211C, and 211K that form toner images of four colors, yellow (Y), magenta (M), cyan (C), and black (K). The image forming section 201B also includes an intermediate transfer unit 201C, a secondary transfer roller 217, and a fixing section 201E. The image forming section 201B also includes various motors (drum drive motor 610, belt drive motor 611, development drive motor 612, etc.) and various high voltage power supplies (charging power supply 600, development power supply 601, primary transfer power supply 602, etc.) (FIG. 2).

[0015] Each of the process cartridges 211Y, 211M, 211C, and 211K has a photosensitive drum 212 as a photosensitive member (image carrier), and is a process unit for forming a toner image on the surface of the photosensitive drum 212 by an electrophotographic process. Each of the process cartridges 211Y, 211M, 211C, and 211K is detachably mountable to a cartridge mounting portion provided in the printer main body 201A.

[0016] Each of the process cartridges 211Y, 211M, 211C, and 211K includes a photosensitive drum 212, a charger 213 as a charging means, a developing unit 214 as a developing unit, and a cleaning blade 231 as a cleaning unit. The photosensitive drum 212 is a photosensitive body molded into a drum shape (cylindrical shape) and has a photosensitive layer made of a photosensitive material such as an organic photosensitive material. The charger 213 is, for example, a charging roller that is arranged in contact with or in close proximity to the surface (outer circumferential surface) of the photosensitive drum 212 and charges the surface of the photosensitive drum 212 by proximity discharge. The charger 213 is not limited to a charging roller, and may be, for example, a corona charger that charges the surface of the photosensitive drum 212 by corona discharge from a wire. The developing unit 214 includes a container (developing container) that contains a developer containing toner, and a developing roller 214a (developer carrier) that carries the developer and supplies it to the photosensitive drum 212.

[0017] The cleaning blade 231 is a plate-like member having appropriate elasticity and elongated in the direction of the rotation axis of the photosensitive drum 212. The tip of the cleaning blade 231 abuts against the surface of the photosensitive drum 212 with a predetermined abutment pressure. In this embodiment, the cleaning blade 231 is arranged so that the direction toward the tip of the cleaning blade 231 is opposite to the rotation direction of the photosensitive drum 212 (counter direction). Note that the cleaning blade 231 may be arranged so that the direction toward the tip of the cleaning blade 231 is along the rotation direction of the photosensitive drum 212 (with direction).

[0018] The printer main body 201A further includes a toner cartridge 215 for supplying toner to the developing devices 214 of the process cartridges 211Y, 211M, 211C, and 211K.

[0019] The intermediate transfer unit 201C is disposed above the four process cartridges 211Y to 211K. The intermediate transfer unit 201C includes an intermediate transfer belt 216 as an intermediate transfer body, a drive roller 216a, a tension roller 216b, and four primary transfer rollers 219. The intermediate transfer belt 216 is an endless belt wound around the drive roller 216a and the tension roller 216b. The primary transfer rollers 219 are disposed on the inside of the intermediate transfer belt 216 so as to come into contact with the intermediate transfer belt 216 at a position facing the photosensitive drum 212. When the drive roller 216a is driven by a drive unit (not shown), the intermediate transfer belt 216 rotates in the direction of the arrow in the figure.

[0020] The secondary transfer roller 217 is disposed in a position facing the drive roller 216a so as to be in contact with the outer surface of the intermediate transfer belt 216. The secondary transfer roller 217 is an example of a transfer means (secondary transfer means) that transfers an image formed on the intermediate transfer belt 216 to the sheet S. A secondary transfer portion 201D is formed as a nip portion between the intermediate transfer belt 216 and the secondary transfer roller 217.

[0021] The fixing unit 201E is disposed above the secondary transfer unit 201D. The fixing unit 201E includes a heating roller 220b as a heating member (fixing member), a pressure roller 220a as a pressure member, and a heating unit for heating the heating roller 220b. A fixing nip is formed between the heating roller 220b and the pressure roller 220a. The heating unit is, for example, a halogen lamp or a coil unit for induction heating.

[0022] The printer main body 201A further includes a cassette feed section 230, a manual feed section 235, and a registration roller pair (hereinafter, referred to as a registration roller pair 240). The printer main body 201A also includes a first discharge roller pair 225a, a second discharge roller pair 225b, a double-sided reversing section 201F, and a stacking section 223 (discharge tray).

[0023] The cassette feeding section 230 is provided at the bottom of the printer body 201A. In this embodiment, the printer body 201A includes four cassette feeding sections 230 arranged vertically. The cassette feeding section 230 feeds the sheets S stacked in the cassette 1 one by one by the feeding unit 5 toward the image forming section 201B.

[0024] Each cassette feeding section 230 has a cassette 1 (storage section, storage, feeding tray) that stores sheets S, and a feeding unit 5 as a feeding means that feeds the sheets S. A support plate (middle plate) is provided in the cassette 1 as a sheet support section that supports a sheet stack. The feeding unit 5 has a pickup roller 2 that feeds the sheets S from the cassette 1, and a separation roller pair as a separation means that separates the sheets S when the pickup roller 2 feeds out multiple sheets S. The separation roller pair includes a feed roller 3 that rotates along the sheet feeding direction, and a retard roller to which a driving force in a direction opposite to the sheet feeding direction is input via a torque limiter. The roller pair including the retard roller is an example of a separation means, and the sheets S may be separated by, for example, a pad-shaped elastic member (friction pad) that contacts the feed roller 3. Further, the feeding unit 5 consisting of three rollers is an example of a feeding means, and may be configured such that a separating member such as a friction pad is in contact with a roller member that feeds out the sheet S from the cassette 1, for example.

[0025] The manual feed section 235 (multipurpose feed section) is provided on the right side of the printer body 201A. The manual feed section 235 has a manual tray 6 as a sheet support section (sheet placement section) that supports the sheets S, and a feeding unit as a feeding means that feeds the sheets S. The configuration of the feeding unit may be the same as the feeding unit 5 of the cassette feeding section 230. The manual feed section 235 feeds the sheets S placed by the user on the manual tray 6 that protrudes to the right side of the printer body 201A, one by one, toward the image forming section 201B by the feeding unit 5.

[0026] The cassette feeding section 230, the manual feeding section 235, and the extended feeding device 500 are all examples of a sheet feeding section that feeds the sheets S in the image forming apparatus 200. The extended feeding device 500 will be described in detail later.

[0027] The first discharge roller pair 225a, the second discharge roller pair 225b, and a part of the duplex inversion unit 201F are disposed above the fixing unit 201E. The first discharge roller pair 225a and the second discharge roller pair 225b are discharge means for discharging the sheet S on which an image has been formed. The duplex inversion unit 201F includes a reversible reversible roller pair 222 and a re-conveyance path R. In the case of an image forming operation (duplex printing) in which images are formed on both sides of the sheet S, the duplex inversion unit 201F is configured to reverse the sheet S on which an image has been formed on the first side by the reversal roller pair 222 and convey it again toward the image forming unit 201B via the re-conveyance path R.

[0028] (Image formation operation) Next, a description will be given of an image forming operation of the printer 201. Here, a case will be described in which an image is formed on a sheet S based on image information read from an original by the image reading device 202.

[0029] First, when image information of an original is read by the image reading device 202, the image information is subjected to image processing and then transmitted as a video signal to the exposure device 210 of the image forming unit 201B. In the image forming unit 201B, the photosensitive drum 212 is rotated at a predetermined peripheral speed in each of the process cartridges 211Y to 211K. The charger 213 applies a charging bias (charging voltage) to uniformly charge the surface of the photosensitive drum 212 to a predetermined polarity and potential. The exposure device 210 irradiates light toward each photosensitive drum 212 based on the video signal to expose the photosensitive drum 212. As a result, an electrostatic latent image corresponding to a monochrome image of yellow, magenta, cyan, and black is formed on each photosensitive drum 212. The developing device 214 supplies a developer containing toner to the photosensitive drum 212 to develop the electrostatic latent image into a monochrome toner image. Specifically, when a developing bias (developing voltage) is applied to the developing roller 214a, the potential difference between the surface of the photosensitive drum 212 and the developing roller 214a causes the toner to be transferred from the developing roller 214a to the photosensitive drum 212. As a result, the toner adheres to the surface of the photosensitive drum 212 in accordance with the potential distribution, and the electrostatic latent image is visualized as a toner image.

[0030] Thereafter, a transfer bias (primary transfer voltage) is applied to each primary transfer roller 219, whereby a single-color toner image is primarily transferred from each photosensitive drum 212 to the intermediate transfer belt 216. During the primary transfer, multiple transfer is performed such that the four single-color toner images are superimposed on each other, thereby forming a full-color toner image on the intermediate transfer belt 216. Foreign matter such as residual toner that remains on the photosensitive drum 212 without being transferred to the intermediate transfer belt 216 is scraped off by a cleaning blade 231 and removed from the surface of the photosensitive drum 212.

[0031] In parallel with the formation of a toner image by the image forming unit 201B, sheets S are fed one by one toward the image forming unit 201B from any one of the cassette feeding unit 230, the manual feeding unit 235, and the extended feeding device 500. For example, when a sheet S is fed from the cassette feeding unit 230, the sheet S is picked up from the cassette 1 by the pickup roller 2, and the sheet S is conveyed toward the pair of registration rollers 240 by the feed roller 3.

[0032] The leading edge of the sheet S abuts against the nip portion of the registration roller pair 240, which is in the stopped state, and a bend (loop) is formed in the sheet S. This causes the leading edge of the sheet S to rotate so as to follow the nip portion of the registration roller pair 240, and a relatively minor skew of the sheet S is corrected. Thereafter, the registration roller pair 240 starts to be driven, and the sheet S is transported to the secondary transfer unit 201D.

[0033] In the secondary transfer section 201D, a transfer bias (secondary transfer voltage) is applied to the secondary transfer roller 217, whereby an image (full-color toner image) is secondarily transferred from the intermediate transfer belt 216 to the sheet S. The sheet S that has passed through the secondary transfer section 201D is transported to the fixing section 201E, where the image is fixed. The fixing section 201E fixes the image on the sheet S by heating and pressurizing the toner on the sheet S while nipping and transporting the sheet S at a fixing nip.

[0034] In the case of single-sided printing in which an image is formed only on the first side of the sheet S, the sheet S that has passed through the fixing unit 201E is discharged to the discharge space V by the first discharge roller pair 225a or the second discharge roller pair 225b, and is stacked on the stacking unit 223 provided at the bottom of the discharge space V. In the case of double-sided printing in which images are formed on the first and second sides of the sheet S, the sheet S that has an image transferred to the first side and has passed through the fixing unit 201E is sent to the reversing roller pair 222. The sheet S is reversed and conveyed by the reversing roller pair 222, and conveyed again to the registration roller pair 240 via the re-conveyance path R, where skew is corrected. Then, the sheet S passes through the secondary transfer unit 201D and the fixing unit 201E again, and an image is formed on the second side of the sheet S. The sheet S with the images formed on the first and second sides is discharged to the discharge space V by the first discharge roller pair 225a or the second discharge roller pair 225b, and is stacked on the stacking unit 223.

[0035] (Extended Feeding Device) Next, the details of the extended feeding device 500 will be described with reference to Fig. 1, Fig. 3, and Fig. 4. Fig. 3 is a schematic diagram showing the configuration of the extended feeding device 500 according to this embodiment. Fig. 4 is a schematic diagram showing a cross section of the extended feeding device 500 according to this embodiment cut in the sheet width direction.

[0036] The extended feeding device 500 is a large-capacity sheet feeding device capable of storing and continuously feeding more sheets S than the cassette feeding unit 230 in the printer 201. As shown in Fig. 1, the extended feeding device 500 has a storage case 510 (storage deck) as a sheet storage unit, a feeding unit 506 as a feeding means for feeding the sheets, a pair of pull-out rollers 504, and a feeding sensor 505.

[0037] The feeding unit 506 has a pickup roller 501 that picks up a sheet S from a storage 510, and a pair of separation rollers as a separation means that separates the sheets S when the pickup roller 501 picks up a plurality of sheets S. The pair of separation rollers includes a feed roller 502 that rotates along the sheet feeding direction, and a retard roller 503 to which a driving force in a direction opposite to the sheet feeding direction is input via a torque limiter.

[0038] The pull-out roller pair 504 is disposed downstream of the feed roller 502 in the sheet feeding direction. The pull-out roller pair 504 conveys the sheet S toward the printer 201 so as to pull the sheet S from the separation roller pair. The feed sensor 505 detects the sheet S at a detection position between the feed roller 502 and the pull-out roller pair 504 in the sheet feeding direction. The feed sensor 505 outputs a detection signal according to the presence or absence of the sheet S at the detection position. The control unit of the extended feed device 500 or the printer 201 can detect the passage of the sheet S based on the detection signal of the feed sensor 505 and monitor the feeding operation.

[0039] As shown in FIG. 3, storage 510 includes a lifter plate 514, side end regulating plates 511 and 512, a rear end regulating plate 513, and air blowing portions 511A and 512A.

[0040] The lifter plate 514 is a sheet support portion (stacking portion) on which a plurality of sheets S (sheet stack) are stacked and which supports the stacked sheet stack. The lifter plate 514 can be raised and lowered relative to the housing of the storage 510 by a lifting mechanism (hanging wire and wire winding mechanism) (not shown). The position of the lifter plate 514 is controlled according to the amount of the stack of sheets so that, for example, the topmost sheet S is at a height at which it can be fed by the feeding unit 506.

[0041] The side end regulating plates 511 and 512 regulate the position of the end (side end of the sheet S) in the sheet width direction perpendicular to the sheet feeding direction of the sheet S stacked on the lifter plate 514. The rear end regulating plate 513 regulates the position of the upstream end (rear end of the sheet) of the sheet S in the sheet feeding direction.

[0042] The air blowing units 511A and 512A are mechanisms for handling the sheets S by blowing air onto the end faces of the sheet stack stacked on the lifter plate 514. "Handling" the sheets S means weakening the adhesion between overlapping sheets so that the sheets S are more likely to be separated when fed by the feeding unit 506 (making it difficult for double feeding to occur).

[0043] As shown in FIGS. 3 and 4, air blowing units 511A and 512A of this embodiment are built into side end regulating plates 511 and 512, respectively.

[0044] The air blowing unit 511A has a fan 511b and a blowing nozzle 511a. The fan 511b is a unit in which a rotary blade that generates an air flow and a motor that rotates the rotary blade are integrated. The blowing nozzle 511a is formed to guide air from the fan 511b and blow the air to the side end of the sheet stack on the lifter plate 514. The blowing nozzle 511a opens at the regulating surface of the side end regulating plate 511 (the surface facing the side end of the sheet stack).

[0045] Similarly, the air blowing unit 512A has a fan 512b and a blowing nozzle 512a. The fan 512b is a unit that integrates a rotary blade that generates an airflow and a fan motor that rotates the rotary blade. The blowing nozzle 512a is formed to guide the air from the fan 512b and blow the air against the side end of the sheet stack on the lifter plate 514. The blowing nozzle 512a opens at the regulating surface of the side end regulating plate 512 (the surface facing the side end of the sheet stack).

[0046] In addition, the side end regulating plates 511, 512 are provided with holding plates 511c, 512c near the openings of the blowing nozzles 511a, 512a to prevent the sheet S, upon which air is blown, from floating up and climbing over the side end regulating plates 511, 512.

[0047] The fans 511b and 512b may be, for example, a sirocco fan or a propeller fan (axial flow fan). The air blowing units 511A and 512A may be disposed as separate units that are not built into the side end regulating plates 511 and 512.

[0048] (Image forming system control system) Next, the configuration of a control system in the image forming apparatus 200 will be described with reference to Fig. 2. Fig. 2 is a block diagram showing the control system of the image forming apparatus according to this embodiment.

[0049] The control unit 100 according to this embodiment is provided in, for example, a printer 201. The control unit 100 is a control circuit including a CPU 101 that executes a program used to control the image forming apparatus, and a ROM 102 and a RAM 103 that serve as storage units that store the program and data used to control the image forming apparatus. The control unit 100 is a control unit that controls the operation of the entire image forming apparatus 200 including the extended feeding device 500. The image forming apparatus 200 may have a sub-control unit mounted on the extended feeding device 500 to control each unit of the extended feeding device 500 based on a command from the control unit 100.

[0050] The control unit 100 is connected to a host device 900 and an operation unit 730, and performs signal processing and sequence control for various process devices while exchanging information with them. The host device 900 is an external device such as a personal computer, an image scanner, or a facsimile.

[0051] The control unit 100 is also electrically connected to the above-mentioned fans 511b and 512b, the feed sensor 505, various motors (520, 521, 610, 611, 612), various high voltage power supplies (600, 601, 602), and an environment sensor 620.

[0052] The feed motor 520 is a drive source that drives the feed unit 506. The transport motor 521 is a drive source that drives the pull-out roller pair 504. The charging power supply 600 is a circuit that generates a charging voltage to be applied to the charger 213 (FIG. 1). The development power supply 601 is a circuit that generates a development voltage to be applied to the development roller 214a (FIG. 1). The primary transfer power supply 602 is a circuit that generates a primary transfer voltage to be applied to each primary transfer roller 219 (FIG. 1). The drum drive motor 610 is a drive source that rotates and drives each photosensitive drum 212. The belt drive motor 611 is a drive source that rotates and drives the drive roller 216a (FIG. 1) that drives the intermediate transfer belt 216. The development drive motor 612 is a drive source that rotates and drives the development roller 214a (FIG. 1). The environmental sensor 620 is an example of an environmental detection unit that detects the environmental conditions of the environment in which the image forming apparatus 200 is installed, and detects, for example, the temperature and humidity of the air taken into the housing of the image forming apparatus 200.

[0053] During the image forming operation, the drum drive motor 610 and the belt drive motor 611 rotate the photosensitive drums 212 and the intermediate transfer belt 216 at a predetermined rotation speed (circumferential speed). The predetermined rotation speed is the length of a toner image formed by the image forming unit 201B per unit time in the sub-scanning direction, and is called the process speed.

[0054] (Operation when blowing air) Next, the state of the sheets S when air is blown onto the sheet stack by the air blowing units 511A and 512A will be described with reference to Fig. 4. Fig. 4 illustrates the state of the extended feeding device 500 according to this embodiment when the air blowing units 511A and 512A are blowing air onto the sheet stack (hereinafter referred to as "air blowing operation").

[0055] 4, air blown from fans 511b, 512b of air blowing units 511A, 512A flows along blowing nozzles 511a, 512a as indicated by arrows A1, A2, and is blown onto the sides of the sheet stack. Then, the air enters the gaps between several to several tens of sheets located at the top of the sheet stack, causing sheets S to float up. Pressing plates 511c, 512c prevent sheets S from floating up excessively.

[0056] By floating the sheets S with air, the adhesive force between the sheets is reduced (the sheet stack is loosened), making it easier to feed the sheets S. For example, in the case of sheets S having a smooth surface such as coated paper, the adhesive force between the sheets is strong, and therefore there is a possibility that the pickup roller 501 will not properly dispense the sheets S. Specifically, even if the pickup roller 501 applies a conveying force to the top sheet S, the top sheet S may not move while being in adhesive contact with the sheets S below it. By loosening the sheet stack by blowing air, the adhesive force between the sheets is reduced, making it easier for the pickup roller 501 to dispense the top sheet S.

[0057] Hereinafter, blowing air onto the sheet stack by driving the fans 511b and 512b is referred to as an "air blowing operation" or an air handling operation. The air blowing operation is an example of an adjustment operation for adjusting the conditions related to the sheet feeding. The air blowing operation in this embodiment is performed to weaken (reduce) the adhesion force between the sheets, which is a condition related to the sheet feeding, to a level at which stable feeding by the feeding unit 506 is possible.

[0058] The air handling units 511A and 512A described in this embodiment are an example of an air handling mechanism that uses air to handle sheets, and an air handling mechanism having another configuration may be used. For example, instead of or in addition to the air blowing units 511A and 512A that blow air to the side ends (ends in the sheet width direction) of the sheet stack, an air handling mechanism that blows air to the leading end of the sheet stack (downstream end in the sheet feeding direction) may be used.

[0059] (Basic flow of a print job) Next, a basic flow of a print job according to this embodiment will be described with reference to Fig. 5. Fig. 5 is a flow chart showing an example of control related to control of a print job when a sheet S is fed from the extended feeding device 500. The control content shown in Fig. 5 is the basis of control in each embodiment described below.

[0060] When a print job (also simply referred to as a "job") is input, the control unit 100 starts the following process (S201). A print job or an image forming job is a series of tasks for forming an image on each sheet S while conveying the sheets S one by one in the image forming apparatus and outputting a product. The number of sheets S on which images are formed in the print job (requested number) is designated in advance by a user when inputting the print job through an operation of the operation unit 730 (FIG. 1) or a screen operation in the host apparatus. The print job includes the above-mentioned image forming operation, a preparatory operation before starting the image forming operation, and a post-processing operation after accommodating the image forming operation. The image forming operation includes a feeding operation in which the sheet feeding unit feeds one sheet S, and an operation in which the image forming unit 201B forms an image on the sheet S. As described below, the air blowing operation may be performed as part of a preparatory operation before starting the image forming operation for the first sheet of the print job, or may be performed after the image forming operation for the first sheet is started.

[0061] When the execution of a print job is started, the control unit 100 executes an air blowing operation (Sα). Specifically, in the extended feeding device 500, the driving of the fans 511b, 512b of the air blowing units 511A, 512A is started (S202) based on a command from the control unit 100, and the air blowing operation is started. When a predetermined time has elapsed since the driving of the fans 511b, 512b was started (Yes in S203), the driving of the fans 511b, 512b is stopped (S204), and the air blowing operation is ended. The sheet stack is separated by the execution of the air blowing operation. That is, several to several tens of sheets S located at the top of the sheet stack on the lifter plate 514 are lifted, and the adhesion force between the sheets is reduced.

[0062] The above-mentioned predetermined time is the length of time for which air is blown onto the sheet stack by the air blowing operation (hereinafter, referred to as the air blowing time). The air blowing time is the length of time for the air blowing operation, which is an example of an adjustment operation. In this embodiment, the air blowing time is the length of time from when the fans 511b, 511b start to be driven (when the fan motor starts to be energized) to when the fans 511b, 512b stop to be driven (when the fan motor is deenergized). Since the fans 511b, 512b start to be driven from a rotation stop state, it is desirable to consider the time until the number of rotations (rotation speed) of the fans 511b, 512 reaches a desired number of rotations and the time until the floating of the sheet S becomes stable, as the air blowing time. The predetermined time is set to, for example, 10 seconds. The predetermined time may be set to a different value depending on the material of the sheet S (particularly, whether the material is highly smooth, such as coated paper) and / or the size.

[0063] After the air blowing operation, a feeding operation is executed (S205). The feeding operation is a series of operations in which one sheet S is fed toward the image forming section 201B by the feeding unit 506 as a feeding means. In this embodiment, a series of operations from when the feeding motor 520 starts driving the feeding unit 506 while the pickup roller 501 is in contact with the uppermost sheet S, until the feeding sensor 505 detects the rear end of the sheet S, is called the "feeding operation."

[0064] Specifically, in the extended feeding device 500, based on a command (S205) to start the feeding operation from the control unit 100, the feeding motor 520 drives the feeding unit 506 with the pickup roller 501 in contact with the uppermost sheet S. As a result, the pickup roller 501 picks up the sheet S from the storage 510, and the sheet S is further separated by the feed roller 502 and the retard roller 503. The sheet S that has passed through the separation nip between the feed roller 502 and the retard roller 503 is further conveyed by the pull-out roller pair 504 driven by the conveying motor 521, and is delivered to the printer body 201A. In addition, in the process in which the sheet S is conveyed from the separation nip to the pull-out roller pair 504, the leading and trailing ends of the sheet S are detected by the feeding sensor 505.

[0065] The feeding operation is repeated for each sheet S until the number of sheets S fed by the feeding operation (S205) from the start of the print job (hereinafter referred to as the number of sheets fed after the start of the job) reaches the number of sheets required for the print job (i.e., while S206 is No). When the number of sheets S fed from the extended feeding device 500 reaches the number of sheets required for the print job (Yes in S206), the control unit 100 ends the process (S207).

[0066] In this embodiment, the air blowing operation (Sα) is not performed while the feeding operation (S205) is being performed. This is to reduce the possibility that the sheet S will be skewed due to the simultaneous execution of the feeding operation and the air blowing operation. Specifically, when the sheet S floats due to the air, the sheet S may bend and the side edge of the sheet S may separate from the side edge regulating plates 511 and 512. In this case, the side edge regulating plates 511 and 512 may not be able to suppress the skew of the sheet S, and as a result, the sheet S may be skewed. If the amount of skew of the fed sheet S (the skew of the leading edge of the sheet relative to the sheet width direction) is large, the skew cannot be sufficiently corrected by the registration roller pair 240, and the image may be skewed. Therefore, in this embodiment, the air blowing operation is not performed while the feeding operation is being performed.

[0067] While the feeding operation (S205) is repeatedly performed, the sheets S floated by the air blowing operation (Sα) descend due to gravity, and the air between the sheets gradually escapes. In other words, the sheet stack gradually tries to return to the state before the air blowing operation was performed (state in which the adhesion between the sheets is strong). Also, when the number of sheets in the sheet stack stacked on the lifter plate 514 is large, it is difficult to separate all the sheets S in the sheet stack with one air blowing operation.

[0068] Therefore, in this embodiment, each time the number of sheets S fed by the feeding operation (S205) since the start of a print job (number of sheets fed after the start of a job) increases by a predetermined number, the feeding operation is temporarily stopped and an air blowing operation (Sα) is performed. That is, the control unit 100 performs the air blowing operation before the number of sheets fed after the start of a job reaches the number of sheets requested by the print job (No in S206) and if the number of sheets fed after the start of a job has increased by a predetermined number since the end of the previous air blowing operation (Yes in S208). The control unit 100 does not perform the air blowing operation until the number of sheets fed after the start of a job has increased by a predetermined number from the end of the previous air blowing operation (No in S208).

[0069] The above-mentioned "predetermined number" is set as the number of sheets S that can be handled by one air blowing operation. In other words, the "predetermined number" represents the number of sheets S that can be fed after the air blowing operation is performed without performing another air blowing operation.

[0070] The predetermined number is set to, for example, 10 sheets. In this case, when the number of sheets requested by the print job is 10 or less, after the air blowing operation (Sα) is performed before the first sheet S is fed, the 10 sheets S are fed without performing the air blowing operation again. On the other hand, when the number of sheets requested by the print job is 50, after the air blowing operation (Sα) is performed before the first sheet S is fed, one air blowing operation (Sα) is performed every time the number of sheets fed after the start of the job increases by 10. Therefore, a total of five air blowing operations (Sα) are performed until the print job is completed.

[0071] When the feeding operation is repeated without performing the air blowing operation (Sα) (No in S208), the feeding operation of the next sheet is started after a predetermined interval (paper interval) from the completion of the feeding operation of the preceding sheet. When the air blowing operation (Sα) is performed (Yes in S208), the time from the completion of the feeding operation of the preceding sheet to the start of the feeding operation of the next sheet (the sheet that is fed first after the air blowing operation) may be longer than the predetermined interval.

[0072] In this manner, in this embodiment, when a print job with a requested number of sheets greater than a predetermined number is executed, the feeding operation is temporarily stopped, an air blowing operation (Sα) is executed, and the feeding operation is resumed after the air blowing operation (Sα) is executed. In other words, when a job for forming images on a number of sheets greater than a predetermined number is executed, the control means is configured to stop the feeding operation after the predetermined number of sheets have been fed by the feeding means, execute an adjustment operation for adjusting conditions related to sheet feeding, and resume the feeding operation after the adjustment operation is executed.

[0073] During execution of a print job, the image forming unit 201B is normally driven continuously. However, if the image forming unit 201B is driven continuously when the feeding operation is temporarily stopped and the air blowing operation is performed, the amount of wear of the photosensitive drum 212 relative to the cumulative number of printed sheets of the image forming apparatus 200 may increase.

[0074] That is, while the feeding operation is interrupted to perform the air blowing operation, the sheet S is not fed to the image forming unit 201B, and therefore the creation of the toner image to be formed on the sheet S in the image forming unit 201B is also stopped. In this way, the time during which the image forming unit 201B is driven without creating a toner image is extended, and the amount of wear of the photosensitive drum 212 relative to the cumulative number of printed sheets increases. That is, the amount of wear of the photosensitive drum 212 relative to the cumulative number of printed sheets of the image forming apparatus 200 increases compared to when the air blowing operation is not performed or when the air blowing operation is performed simultaneously with the feeding operation without stopping the feeding operation. As a result, the number of printable sheets of the photosensitive drum 212 (the cumulative number of printed sheets that requires cartridge replacement) may be smaller compared to when the air blowing operation is not performed. Also, when the photosensitive drum 212 is part of the process cartridges 211Y to 211K, the number of printable sheets of the process cartridges (the cumulative number of printed sheets that requires cartridge replacement) may be smaller compared to when the air blowing operation is not performed.

[0075] The wear rate of the photosensitive drum 212 varies depending on a number of factors. For example, the photosensitive drum 212 wears due to rubbing against the cleaning blade 231 (FIG. 1). When a charging voltage is applied to the charger 213, the surface of the photosensitive drum 212 deteriorates due to discharge between the charger 213 and the photosensitive drum 212, accelerating the wear of the photosensitive drum 212. Although the factors that wear the photosensitive drum 212 differ depending on the specific configuration of the image forming unit 201B, basically, the wear of the photosensitive drum 212 progresses while the image forming unit 201B is being driven. Note that even in a configuration in which the cleaning blade 231 is not provided, the photosensitive drum 212 can wear due to rubbing against the intermediate transfer belt 216, etc.

[0076] Therefore, in each example of this embodiment described below, when an air blowing operation is performed during execution of a print job, a process such as temporarily stopping the driving of the image forming unit 201B is performed, which makes it possible to suppress the progress of wear on the photosensitive drum 212 while the feeding operation is interrupted to perform the air blowing operation.

[0077] Example 1 The control of the image forming apparatus 200 according to the first embodiment will be described. In the first embodiment, when the feeding operation is temporarily stopped during the execution of a print job and the air blowing operation is executed, the operation of the image forming unit 201B is temporarily stopped. Furthermore, whether or not the air blowing operation can be executed and the execution time (air blowing time) are changed according to the type of the sheet S to be fed and the environmental conditions of the installation location of the image forming apparatus 200.

[0078] First, a description will be given of whether or not the air blowing operation can be performed depending on the type of sheet S. The type of sheet S is set in advance by the user through screen operations on the operation unit 730 or the like when a print job is input.

[0079] In the first embodiment, if the type of sheet S used in the print job is one in which the adhesion between sheets is weak, the air blowing operation is not performed. An example of a sheet with weak adhesion between sheets is plain paper. For sheets with weak adhesion between sheets, that is, sheets that are relatively easy to separate without performing an air blowing operation, productivity can be improved by not performing an air blowing operation. On the other hand, in the first embodiment, if the type of sheet S used in the print job is one in which the adhesion between sheets is strong, the air blowing operation is performed. An example of a type of sheet with strong adhesion between sheets is coated paper and waterproof paper.

[0080] Next, the setting of the air blowing time according to the environmental conditions will be described. In the first embodiment, the control means changes the time length of the air blowing operation according to the environmental conditions detected by the environmental detection means. In the first embodiment, the air blowing time is determined based on the temperature and humidity detected by the environmental sensor 620. That is, the environmental conditions in the first embodiment are a combination of temperature and humidity (hereinafter collectively referred to as temperature and humidity information). Note that only one of temperature or humidity may be used as the environmental condition. Humidity may be either relative humidity or absolute humidity (absolute water content).

[0081] FIG. 6 shows an example of a setting standard for the air blowing time according to the temperature and humidity information. In the first embodiment, as shown in FIG. 6, the environmental conditions are divided into three sections, (1) to (3), according to the temperature and humidity values, and different air blowing times are set between sections (1) to (3). Section (3) is an environment with a large amount of moisture in the air, and the adhesion between sheets is likely to be strong due to moisture. For this reason, when the temperature and humidity information corresponds to section (3), it is preferable to set the air blowing time long to more reliably separate the sheet stack. On the other hand, section (1) is an environment with a small amount of moisture in the air, and the adhesion between sheets is unlikely to be strong. For this reason, when the temperature and humidity information corresponds to section (1), it is preferable to set the air blowing time short to increase the productivity of the image forming apparatus 200. Section (2) is an environment with a medium amount of moisture in the air. For this reason, when the temperature and humidity information corresponds to section (2), it is preferable to set the air blowing time to a value between sections (1) and (3) to balance the separability and productivity.

[0082] In the first embodiment, when the temperature and humidity information corresponds to category (1), the air blowing time is set to 5 seconds, when the temperature and humidity information corresponds to category (2), the air blowing time is set to 10 seconds, and when the temperature and humidity information corresponds to category (3), the air blowing time is set to 30 seconds.

[0083] The above is merely an example, and it is possible to appropriately change the number of environmental condition divisions, boundary positions, etc. Also, for example, a setting may be made such that the air blowing operation is not performed in an environment with a low moisture content in the air.

[0084] (Print job control method in the first embodiment) When a print job is input, the control unit 100 starts the following process (S301). When the execution of the print job is started, the control unit 100 determines the air blowing time based on the temperature and humidity information and executes the air blowing operation (Sα). Specifically, in the extended feeding device 500, the driving of the fans 511b and 512b of the air blowing units 511A and 512A is started based on a command from the control unit 100 (S302), thereby starting the air blowing operation. When a predetermined time has elapsed since the driving of the fans 511b and 512b started (Yes in S303), the driving of the fans 511b and 512b is stopped (S304), and the air blowing operation ends. The predetermined time in S303 is the air blowing time determined based on the temperature and humidity information. The sheet stack is handled by executing the air blowing operation.

[0085] After the air blowing operation, the control unit 100 starts the operation of the image forming unit 201B (S305). In this embodiment, "the operation of the image forming unit 201B" refers to rotating the photosensitive drum 212 and the intermediate transfer belt 216 at the process speed, and applying the charging voltage, the developing voltage, and the primary transfer voltage at the voltage values ​​during image formation. In other words, in this embodiment, "the operation of the image forming unit 201B" refers to an operating state in which various motors and various high-voltage power supplies are ramped up to a predetermined rotation speed or output voltage, and a toner image can be created when exposure by the exposure device 210 is started based on a video signal.

[0086] Specifically, the control unit 100 starts up various motors (drum drive motor 610, belt drive motor 611, development drive motor 612) and various high voltage power supplies (charging power supply 600, development power supply 601, primary transfer power supply 602). When the start-up of each element of the image forming unit 201B is completed, the control unit 100 feeds one sheet S by a feeding operation (S306). Thereafter, an image is formed on the fed sheet S by the image forming unit 201B.

[0087] The control unit 100 repeatedly executes the feeding operation (S306) until the number of sheets fed after the start of the job reaches the number of sheets required for the print job (i.e., while S307 is No). When the number of sheets fed after the start of the job reaches the number of sheets required for the print job (Yes in S306), the control unit 100 ends the process (S314).

[0088] While repeatedly executing the feeding operation (S306), the control unit 100 temporarily stops the feeding operation and executes the air blowing operation (Sα) each time the number of sheets fed after the start of the job increases by a predetermined number. That is, the control unit 100 executes the air blowing operation before the number of sheets fed after the start of the job reaches the number of sheets required for the print job (No in S307) and if the number of sheets fed after the start of the job has increased by a predetermined number since the end of the previous air blowing operation (Yes in S308). The control unit 100 does not execute the air blowing operation until the number of sheets fed after the start of the job has increased by a predetermined number since the end of the previous air blowing operation (No in S308). The predetermined number is, for example, 10 sheets, but may be set to a different value depending on the type of sheet S.

[0089] The control content when performing air blowing operation in the middle of a print job, rather than the air blowing operation at the start of a print job (S302 to S304), differs depending on the length of the air blowing time determined based on the temperature and humidity information. "In the middle of a print job" refers to the period after at least one sheet S has been fed after the start of a print job. In other words, if the answer is Yes in S308 in FIG. 7, the process branches depending on the length of the air blowing time.

[0090] When an air blowing operation is performed during a print job, if the air blowing time is long (Yes in S309), the procedure of S310 to S313 in Fig. 7 is executed. Specifically, if the air blowing time value is equal to or greater than a predetermined threshold, the air blowing time is determined to be long. The threshold is, for example, 10 seconds. In this case, if the temperature and humidity information is in category (2) (air blowing time is 10 seconds) or category (3) (air blowing time is 30 seconds), the air blowing time is determined to be long.

[0091] That is, when the air blowing time is long, the control unit 100 stops the operation of the image forming unit 201B (S310) and then executes the air blowing operation (Sα). Specifically, the control unit 100 stops various motors (drum drive motor 610, belt drive motor 611, development drive motor 612), various high voltage power supplies (charging power supply 600, development power supply 601, primary transfer power supply 602), and the exposure device 210 in a predetermined order. In the extended feeding device 500, the driving of the fans 511b and 512b of the air blowing units 511A and 512A is started (S311) based on a command from the control unit 100, and the air blowing operation is started. When a predetermined time has passed since the driving of the fans 511b and 512b was started (Yes in S312), the driving of the fans 511b and 512b is stopped (S313), and the air blowing operation is ended. The predetermined time in S312 is an air blowing time that is determined based on the temperature and humidity information. By performing the air blowing operation, the sheet stack is sorted again.

[0092] When the air blowing operation is completed, the control unit 100 resumes the operation of the image forming unit 201B (S305). That is, the control unit 100 starts up various motors (drum drive motor 610, belt drive motor 611, development drive motor 612), various high voltage power supplies (charging power supply 600, development power supply 601, primary transfer power supply 602), and the exposure device 210. When the start-up of each element of the image forming unit 201B is completed, the control unit 100 resumes the feeding operation (S306). The processing from S306 onwards is the same as that described above.

[0093] On the other hand, when an air blowing operation is performed during a print job, if the air blowing time is short (No in S309), the procedure of S411 to S413 in FIG. 9 is executed. In the first embodiment, if the air blowing time value is less than a predetermined threshold, the air blowing time is determined to be short. The threshold is, for example, 10 seconds. In this case, if the temperature and humidity information is in category (1) (air blowing time is 5 seconds), the air blowing time is determined to be short.

[0094] That is, when the air blowing time is short, the control unit 100 executes the air blowing operation (Sα) without stopping the operation of the image forming unit 201B. Specifically, the control unit 100 executes the air blowing operation (Sα) while operating various motors (drum drive motor 610, belt drive motor 611, development drive motor 612) and various high voltage power supplies (charging power supply 600, development power supply 601, primary transfer power supply 602). In the extended feeding device 500, the driving of the fans 511b, 512b of the air blowing units 511A, 512A is started (S411) based on a command from the control unit 100, thereby starting the air blowing operation. When a predetermined time has elapsed since the driving of the fans 511b, 512b started (Yes in S412), the driving of the fans 511b, 512b is stopped (S413), and the air blowing operation ends. The predetermined time in S412 is an air blowing time that is determined based on the temperature and humidity information. By performing the air blowing operation, the sheet stack is sorted again.

[0095] When the air blowing operation is completed, the control unit 100 resumes the feeding operation (S306 in FIG. 7). In other words, unlike the case where the air blowing time is long (S310 to S313), the operation of the image forming unit 201B is not stopped, so the control unit 100 can resume the feeding operation immediately after the air blowing operation is completed. The process from S306 onwards is the same as that described above.

[0096] (Operation state of image forming unit) The operating state of image forming unit 201B when the air blowing time is long will be described using the sequence chart of FIG. 8 and the flow of FIG.

[0097] When the execution of a print job is started (S301), an air blowing operation (Sα, S302 to S304) is performed for a predetermined air blowing time. After the air blowing operation is performed, the operation of the image forming unit 201B is started (S305). First, the drum drive motor 610 is started (OFF → ON), and after the drum drive motor 610 is started up (that is, after the rotation speed of the photosensitive drum 212 is stabilized at the process speed), various high-voltage power supplies and the development drive motor 612 are sequentially started up (OFF → ON). Specifically, the application of voltage or the driving of the motor is started in the order of the charging power supply 600, the development power supply 601, the development drive motor 612, and the primary transfer power supply 602. After the output voltage of the various high-voltage power supplies and the rotation speed of the development drive motor 612 are stabilized, exposure by the exposure device 210 is started. The ON / OFF of the belt drive motor 611 is synchronized with the ON / OFF of the drum drive motor 610. On the other hand, after the image forming unit 201B starts operating, the feeding motor 520 starts to be driven (OFF→ON), thereby starting the feeding operation and feeding the sheets S one by one (S306). The image forming unit 201B forms an image on the fed sheets S.

[0098] The start timing of the feeding operation (the start of driving the feeding motor 520) may be before or after the start timing of exposure by the exposure device 210. The start timing of the feeding operation and the start timing of exposure vary depending on the length of the sheet transport path from the feeding unit 506 to the secondary transfer section 201D and the path length from the exposure position in the image forming section 201B to the secondary transfer section 201D. For example, when the former length is longer than the latter path length, the schedule may be such that exposure by the exposure device 210 starts after the start of the feeding operation. The path length from the exposure position to the secondary transfer section 201D is the sum of the outer circumferential length of the photosensitive drum 212 from the exposure position to the primary transfer section and the outer circumferential length of the intermediate transfer belt 216 from the primary transfer section to the secondary transfer section 201D.

[0099] When a predetermined number of sheets S counting from the start of a print job are fed and an exposure operation for forming an image on the sheet S is completed, the operations of various high voltage power supplies and various motors are stopped in sequence (S310). In addition, when the last sheet S of the predetermined number is fed, the feed motor 520 is stopped to perform an air blowing operation.

[0100] Then, with the image forming unit 201B and the feed motor 520 stopped, an air blowing operation is performed for a predetermined air blowing time (Sα, S311 to S313). After the air blowing operation is performed, the operation of the image forming unit 201B is resumed (S305), and the feeding operation is resumed (S306). After this, every time a predetermined number of sheets S are fed counting from the end of the previous air blowing operation, the operation of the image forming unit 201B and the feeding operation are stopped, the air blowing operation is performed, and then the operation of the image forming unit 201B and the feeding operation are resumed. This process is repeated.

[0101] In this way, in the first embodiment, when the air blowing operation is performed, the rotation of the photosensitive drum 212 is stopped. In other words, in the first embodiment, when the air blowing operation is performed, the rotation speed of the photosensitive drum 212 is decelerated to 0 mm / sec. As a result, even when the air blowing operation is performed, an increase in the cumulative rotation amount of the photosensitive drum 212 relative to the cumulative number of printed sheets of the image forming apparatus 200 is suppressed compared to a case in which the photosensitive drum 212 is continuously rotated at the process speed. Therefore, it is possible to reduce wear of the photosensitive drum 212 due to friction with the cleaning blade 231, etc. In other words, according to this embodiment, it is possible to provide an image forming apparatus that can suppress a decrease in the number of printable sheets of the photosensitive member.

[0102] As will be described in Example 2 below, when performing the air blowing operation, the same advantage can be obtained even if the rotation of the photosensitive drum 212 is not stopped but is changed to a predetermined speed (second speed) slower than the process speed (first speed). In other words, when performing the adjustment operation, the control means executes a mode in which the rotation of the photosensitive member is stopped or the rotation speed of the photosensitive member is changed from a first speed, which is the rotation speed of the photosensitive member when the image forming means forms an image on a sheet, to a second speed slower than the first speed. This makes it possible to provide an image forming apparatus capable of suppressing a decrease in the number of printable sheets of the photosensitive member.

[0103] In addition, in the first embodiment, when the air blowing operation is performed, the application of the charging voltage is stopped. In other words, in the first embodiment, when the air blowing operation is performed, the voltage applied by the charging power source 600 to the charger 213 is dropped to 0V. As a result, even when the air blowing operation is performed, the charger 213 is continuously applied with the same charging voltage as during image formation, and the increase in the cumulative time during which the charging voltage is applied to the charger 213 is reduced relative to the cumulative number of printed sheets of the image forming apparatus 200. As a result, the deterioration of the surface of the photosensitive drum 212 due to discharge can be suppressed, and the promotion of wear of the photosensitive drum 212 due to the deterioration of the surface can be suppressed. In other words, according to this embodiment, an image forming apparatus capable of suppressing a decrease in the number of printable sheets of the photosensitive member can be provided.

[0104] As will be described in Example 3 below, when performing the air blowing operation, the application of the charging voltage is not stopped, and the charging voltage is changed to a predetermined voltage value (second voltage value) lower than the charging voltage value during image formation (first voltage value), and similar advantages can be obtained. In other words, when performing the adjustment operation, the control means executes a mode in which the voltage applied to the charging means by the voltage application means is changed from a first voltage value, which is the value of the voltage applied to the charging means by the voltage application means when the image forming means forms an image on a sheet, to a second voltage value lower than the first voltage value. This makes it possible to provide an image forming apparatus capable of suppressing a decrease in the number of printable sheets of the photoconductor.

[0105] In the first embodiment, when the air blowing operation is performed, the rotation of the photosensitive drum 212 is stopped and the application of the charging voltage is stopped. This makes it possible to provide an image forming apparatus that can further suppress a decrease in the number of printable sheets of the photosensitive drum.

[0106] Next, the operating state of the image forming unit 201B when the air blowing time is short will be described using the sequence chart of Fig. 10 with reference to the flows of Fig. 7 and Fig. 9. The operation from the start of a print job (S301) to the feeding of a predetermined number of sheets S is the same as that of the sequence chart of Fig. 8, except that the air blowing time is different.

[0107] When a predetermined number of sheets S counted from the start of a print job are fed, an air blowing operation is performed for a predetermined air blowing time (Sα, S411 to S413). Unlike when the air blowing time is long (FIG. 8), the air blowing operation is performed in a state where the operation of the image forming unit 201B is not stopped.

[0108] Then, after the air blowing operation is performed, the feeding operation (S306) is resumed. Also, exposure by the exposure device 210 is resumed, and an image is formed on each fed sheet S. After this, every time a predetermined number of sheets S are fed counting from the previous air blowing operation, the feeding operation is stopped, the air blowing operation is performed, and then the feeding operation is resumed. This process is repeated.

[0109] In this manner, in this embodiment, when the air blowing time is short, the air blowing operation is performed without stopping the operation of the image forming unit 201B, which can reduce the impact of stopping the operation of the image forming unit 201B when there is little benefit to stopping the operation of the image forming unit 201B.

[0110] (Relationship between length of air blowing time and stoppage of image forming unit) The detailed reasons for performing the air blowing operation without stopping the operation of the image forming unit 201B when the air blowing time is short, and the criteria for the air blowing time for determining whether or not to stop the operation of the image forming unit 201B will be described with reference to Figures 11(a) and (b).

[0111] FIG. 11(a) is a graph showing the relationship between the length of air blowing time (horizontal axis) and the rate of decrease in the number of printable sheets of the photosensitive drum 212 (vertical axis). FIG. 11(b) is a graph showing the relationship between the length of air blowing time (horizontal axis) and the rate of decrease in productivity of the image forming apparatus 200 (vertical axis). The horizontal axis of each figure is the time length of one air blowing operation. The vertical axis of FIG. 11(a) shows the degree of decrease in the number of printable sheets of the photosensitive drum 212 when the air blowing operation is performed, with the number of printable sheets of the photosensitive drum 212 when the air blowing operation is not performed being taken as the reference (100%). The "number of printable sheets of the photosensitive drum 212" refers to the cumulative number of printable sheets that can be output without image defects caused by wear of the photosensitive drum 212 when a durability test is performed in which an image forming operation is repeatedly performed to form a predetermined test image on a sheet S from a state in which the photosensitive drum 212 is new. The vertical axis of Figure 11 (b) represents the amount of reduction in productivity when air blowing operation is performed, with the productivity of image forming device 200 (number of printed sheets per unit time in continuous print jobs) when air blowing operation is not performed as the standard (100%).

[0112] 11(a) and (b) are based on the results of a print job in which coated paper is used as sheet S, an air blowing operation is performed once every time 10 sheets of coated paper are fed, and images are formed on a total of 500 sheets of coated paper. The solid lines in Fig. 11(a) and (b) represent the results when the operation of image forming unit 201B is stopped when the air blowing operation is performed, and the dashed lines represent the results when the operation of image forming unit 201B is not stopped when the air blowing operation is performed.

[0113] 11(a) and 11(b), if the operation of image forming unit 201B is not stopped during the air blowing operation, the longer the air blowing time, the greater the decrease in both the number of printable sheets and the rate of decrease in productivity. The reason why the decrease in the number of printable sheets increases according to the length of the air blowing time is that, as described above, the period during which image forming unit 201B is driven without creating a toner image becomes longer, which increases the amount of wear on photosensitive drum 212 relative to the cumulative number of printed sheets. The reason why the decrease in productivity increases according to the length of the air blowing time is because, since the feeding operation is stopped when the air blowing operation is performed, the sheet feeding interval (paper interval) becomes longer compared to the case where the feeding operation is repeated without performing the air blowing operation.

[0114] As shown by the solid line in FIG. 11(a), when the operation of the image forming unit 201B is stopped during the air blowing operation, the rate of decrease in the printable number of sheets is approximately constant regardless of the length of the air blowing time. This is because the rotation of the photosensitive drum 212 is stopped during the air blowing operation, so even if the air blowing time is long, the period during which the image forming unit 201B is driven without creating a toner image does not become long. On the other hand, the reason why the printable number of sheets is decreased compared to the case where the air blowing operation is not performed is because the air blowing operation causes a period during which the photosensitive drum 212 is driven to rotate without creating a toner image. In other words, when the operation of the image forming unit 201B is stopped before the start of the air blowing operation, and when the operation of the image forming unit 201B is resumed after the end of the air blowing operation, a period during which the photosensitive drum 212 is driven to rotate without creating a toner image occurs.

[0115] 11(a), in the region where the air blowing time is 10 seconds or more, it can be seen that stopping the operation of the image forming unit 201B when the air blowing operation is being performed (solid line) is more advantageous. In other words, when the air blowing time is 10 seconds or more, stopping the operation of the image forming unit 201B when the air blowing operation is being performed (solid line) results in a smaller decrease in the number of printable sheets of the photosensitive drum 212 than when the operation of the image forming unit 201B is not stopped (dashed line). This means that if the air blowing time is long, the amount of rotation of the photosensitive drum 212 during the air blowing operation exceeds the increase in the amount of rotation of the photosensitive drum 212 caused by stopping and restarting the operation of the image forming unit 201B.

[0116] On the other hand, when the air blowing time is less than 10 seconds, the rate of decrease in the number of printable sheets on the photosensitive drum 212 is greater when the operation of the image forming unit 201B is stopped during the air blowing operation (solid line) than when the operation of the image forming unit 201B is not stopped (dashed line). This means that when the air blowing time is short, the amount of rotation of the photosensitive drum 212 during the air blowing operation is less than the increase in the amount of rotation of the photosensitive drum 212 that accompanies the stopping and restarting of the operation of the image forming unit 201B.

[0117] As shown in FIG. 11(b), regardless of the length of the air blowing time, the productivity (solid line) when the operation of the image forming unit 201B is stopped during the air blowing operation is lower than the productivity (dashed line) when the operation of the image forming unit 201B is not stopped during the air blowing operation. However, the ratio (X / Y) of the productivity reduction rate X shown by the solid line to the productivity reduction rate Y shown by the dashed line becomes more significant as the air blowing time becomes shorter. This is because a period for the operation of the image forming unit 201B to be stopped and resumed before and after the start and end of the air blowing operation is required. Also, the shorter the air blowing time, the greater the proportion of the period for the operation of the image forming unit 201B to be stopped and resumed in the period from when the feeding operation is stopped to when the feeding operation is resumed after the air blowing operation is performed.

[0118] From the above results, when the air blowing time is long, it is preferable to stop the operation of the image forming unit 201B when the air blowing operation is performed, from the viewpoint of suppressing a decrease in the number of printable sheets on the photosensitive drum 212. Furthermore, when the air blowing time is long, even if the operation of the image forming unit 201B is stopped when the air blowing operation is performed, the impact on the decrease in productivity of the image forming apparatus 200 is relatively small.

[0119] On the other hand, if the air blowing time is long, it is preferable not to stop the operation of the image forming unit 201B when the air blowing operation is being performed, in order to prevent a decrease in the number of printable sheets on the photosensitive drum 212 and a decrease in the productivity of the image forming apparatus 200.

[0120] Therefore, in the first embodiment, if the air blowing time is less than 10 seconds, the operation of the image forming unit 201B is not stopped when the air blowing operation is performed, and if the air blowing time is 10 seconds or more, the operation of the image forming unit 201B is stopped when the air blowing operation is performed. This makes it possible to achieve a high level of printable number and productivity in a configuration in which the length of the air blowing time can be changed according to environmental conditions, etc.

[0121] The air blowing time threshold for determining whether or not to stop the operation of the image forming unit 201B when the air blowing operation is being performed is not limited to the above value (10 seconds). In addition, in this embodiment, a configuration in which the air blowing time is changed based on temperature and humidity information as an example of environmental conditions has been exemplified, but the above-mentioned control can also be applied to cases in which the air blowing time is changed depending on other conditions (for example, the material and size of the sheet S).

[0122] In this way, in the first embodiment, whether or not to stop or slow down the rotation of the photosensitive drum 212 when the air blowing operation is performed is changed depending on the length of the air blowing time. In other words, the mode is a first mode, and the control means executes the first mode when the time length of the adjustment operation is a first length, and executes a second mode in which the rotation speed of the photosensitive drum is maintained at the first speed when the adjustment operation is performed when the time length of the adjustment operation is a second length shorter than the first length. The case where the time length of the adjustment operation is the first length is, for example, when the air blowing time is 30 seconds. The case where the time length of the adjustment operation is the second length is, for example, when the air blowing time is 5 seconds. This makes it possible to achieve a high level of printable number and productivity.

[0123] In the first embodiment, the application of the charging voltage is stopped or the voltage value is lowered during the air blowing operation depending on the length of the air blowing time. In other words, the mode is a first mode, and the control means executes the first mode when the adjustment operation is performed if the time length of the adjustment operation is a first length, and executes the second mode in which the voltage application means maintains the voltage applied to the charging means at the first voltage value when the adjustment operation is performed if the time length of the adjustment operation is a second length shorter than the first length. This makes it possible to achieve a high level of printable number and productivity.

[0124] (Modification) In the first embodiment, the method of stopping the rotation of the photosensitive drum 212 and stopping the application of the charging voltage when the air blowing operation is performed has been described, but only either the rotation of the photosensitive drum 212 or the application of the charging voltage may be stopped. This makes it possible to reduce wear on the photosensitive drum 212, at least compared to a configuration in which the photosensitive drum 212 is continuously rotated at the process speed even during the air blowing operation and a charging voltage of the same voltage value as during image formation is applied.

[0125] If the application of the charging voltage continues while the photosensitive drum 212 is stopped, the surface of the photosensitive drum 212 may locally deteriorate due to continued discharge from the charger 213, which may cause image defects. Therefore, in order to obtain an image with better image quality, if the application of the charging voltage is not stopped when the air blowing operation is performed, it is preferable to also stop the rotation of the photosensitive drum 212 or to decelerate the rotation of the photosensitive drum 212 as in the second embodiment.

[0126] Example 2 An image forming apparatus according to Example 2 will be described. In Example 1, a method for stopping the rotation of the photosensitive drum 212 when performing the air blowing operation was described, but in Example 2, the rotation of the photosensitive drum 212 is decelerated without being stopped when performing the air blowing operation. Hereinafter, elements with common reference symbols to Example 1 have basically the same configurations and functions as those described in Example 1 unless otherwise specified, and differences from Example 1 will be mainly described.

[0127] A print job control method in the second embodiment will be described with reference to Fig. 12. The contents of S301 to S309, S314, and S411 to S413 in Fig. 12 are the same as those in the first embodiment (Figs. 7 and 9), so the description will be omitted.

[0128] As in the first embodiment, the control unit 100 repeatedly executes the feeding operation (S306), and temporarily stops the feeding operation and executes the air blowing operation (Sα) each time the number of sheets fed after the start of the job increases by a predetermined number. That is, the control unit 100 executes the air blowing operation before the number of sheets fed after the start of the job reaches the number of sheets required for the print job (No in S307) and when the number of sheets fed after the start of the job has increased by a predetermined number since the end of the previous air blowing operation (Yes in S308).

[0129] When performing an air blowing operation during a print job, if the air blowing time is long (Yes in S309), the procedure of S510 to S514 in Fig. 12 is executed. Specifically, if the air blowing time value is equal to or greater than a predetermined threshold, the air blowing time is determined to be long. The threshold is, for example, 10 seconds.

[0130] When the air blowing operation is performed during a print job, if the air blowing time is long, the rotation speed of the photosensitive drum 212 is decelerated to a predetermined speed (referred to as "speed B") slower than the process speed (referred to as "speed A" in Figs. 12 and 13). In other words, when performing the adjustment operation, the control means executes a mode in which the rotation of the photosensitive drum is stopped, or the rotation speed of the photosensitive drum is changed from a first speed, which is the rotation speed of the photosensitive drum when the image forming means forms an image on a sheet, to a second speed slower than the first speed. After the rotation speed of the photosensitive drum 212 is decelerated to speed B, the air blowing operation (Sα, S511 to S513) is performed. After the air blowing operation is completed, the rotation speed of the photosensitive drum 212 is accelerated again to the process speed.

[0131] Specifically, in the case of Yes in S309, the control unit 100 sends a command to the drum drive motor 610 to change the rotation speed (circumferential speed) of the photosensitive drum 212 from the process speed (speed A) to a predetermined speed (speed B) slower than the process speed (S510). The process speed (speed A) and the predetermined speed (speed B) are determined in advance and stored in the storage unit (e.g., ROM 102 in FIG. 2) of the control unit 100. In the extended feeding device 500, the driving of the fans 511b and 512b of the air blowing units 511A and 512A is started (S511) based on a command from the control unit 100, and the air blowing operation is started. When a predetermined time (air blowing time) has elapsed since the driving of the fans 511b and 512b was started (Yes in S512), the driving of the fans 511b and 512b is stopped (S513), and the air blowing operation is ended.

[0132] When the air blowing operation is completed, the control unit 100 sends a command to the drum drive motor 610 to change the rotation speed of the photosensitive drum 212 from the predetermined speed (speed B) to the process speed (speed A) (S514). After the rotation speed of the photosensitive drum 212 is stabilized at the process speed (speed A), the control unit 100 resumes the feeding operation (S306).

[0133] In the second embodiment, the operating state of the image forming unit 201B when the air blowing time is long will be described using the sequence chart of Fig. 13 with reference to the flow of Fig. 12. The operation from the start of a print job (S301) until a predetermined number of sheets S are fed is the same as that of the sequence chart of Fig. 8.

[0134] When a predetermined number of sheets S counted from the start of a print job are fed, the photosensitive drum 212 is decelerated from the process speed (speed A) to a predetermined speed (speed B) in order to perform an air blowing operation (S510). Then, while the photosensitive drum 212 is rotated and driven at the predetermined speed (speed B), the air blowing operation is performed for a predetermined air blowing time (Sα, S511 to S513). After the air blowing operation is performed, the photosensitive drum 212 is accelerated from the predetermined speed (speed B) to the process speed (speed A) (S514). In addition, the feed motor 520 starts to be driven, and the feed operation is resumed (S306). Thereafter, every time a predetermined number of sheets S are fed counted from the end of the previous air blowing operation, the rotation speed of the photosensitive drum 212 is decelerated to the predetermined speed, the air blowing operation is performed, and then the rotation speed of the photosensitive drum 212 is accelerated to the process speed. This is repeated.

[0135] In this way, in the second embodiment, when the air blowing operation is performed, the rotation of the photosensitive drum 212 is decelerated to a predetermined speed slower than the process speed. As a result, an increase in the cumulative rotation amount of the photosensitive drum 212 relative to the cumulative number of printed sheets of the image forming apparatus 200 is suppressed compared to a case where the photosensitive drum 212 is continuously rotated at the process speed even when the air blowing operation is performed. Therefore, it is possible to reduce wear of the photosensitive drum 212 due to friction with the cleaning blade 231, etc. In other words, according to this embodiment, it is possible to provide an image forming apparatus that can suppress a decrease in the number of printable sheets of the photosensitive drum.

[0136] In the second embodiment, when the air blowing operation is performed, the voltage output of the various high voltage power supplies is not stopped (OFF). Therefore, compared to the first embodiment, the downtime of the image forming apparatus 200 due to the execution of the air blowing operation can be shortened, and the productivity of the image forming apparatus 200 can be improved.

[0137] (Modification) In the second embodiment, when the air blowing operation is performed, the application of the charging voltage to the charger 213 may be stopped (OFF). This makes it possible to suppress deterioration of the surface of the photosensitive drum 212 due to discharge of the charger 213 while the air blowing operation is performed, and to suppress the promotion of wear of the photosensitive drum 212 due to surface deterioration. In other words, according to this modification, it is possible to provide an image forming apparatus that can further suppress an increase in the amount of wear of the photosensitive member compared to the second embodiment.

[0138] Example 3 An image forming apparatus according to Example 3 will be described. In Example 1, a method for stopping application of charging voltage to charger 213 when performing air blowing operation was described, but in Example 3, the voltage value is lowered without stopping application of charging voltage when performing air blowing operation. Hereinafter, elements with common reference symbols to Example 1 have basically the same configurations and functions as those described in Example 1 unless otherwise specified, and differences from Example 1 will be mainly described.

[0139] A print job control method in the third embodiment will be described with reference to Fig. 14. The contents of S301 to S309, S314, and S411 to S413 in Fig. 14 are the same as those in the first embodiment (Figs. 7 and 9), and therefore description thereof will be omitted.

[0140] As in the first embodiment, the control unit 100 repeatedly executes the feeding operation (S306), and temporarily stops the feeding operation and executes the air blowing operation (Sα) each time the number of sheets fed after the start of the job increases by a predetermined number. That is, the control unit 100 executes the air blowing operation before the number of sheets fed after the start of the job reaches the number of sheets required for the print job (No in S307) and when the number of sheets fed after the start of the job has increased by a predetermined number since the end of the previous air blowing operation (Yes in S308).

[0141] When performing an air blowing operation during a print job, if the air blowing time is long (Yes in S309), the procedure of S610 to S614 in Fig. 14 is executed. Specifically, if the air blowing time value is equal to or greater than a predetermined threshold, the air blowing time is determined to be long. The threshold is, for example, 10 seconds.

[0142] When performing an air blowing operation during a print job, if the air blowing time is long, the output voltage of the various high-voltage power supplies is set to a predetermined voltage value lower than the voltage value when performing the image forming operation (hereinafter referred to as "setting A"). Hereinafter, the predetermined voltage value lower than the voltage value (setting A) when performing the image forming operation is referred to as "setting B". In other words, when performing the adjustment operation, the control means executes a mode in which the voltage applied by the voltage application means to the charging means is changed from a first voltage value, which is the value of the voltage applied by the voltage application means to the charging means when the image forming means forms an image on a sheet, to a second voltage value lower than the first voltage value. After the output voltage of the various high-voltage power supplies is lowered to a predetermined voltage value (setting B), the air blowing operation (Sα, S611 to S613) is performed. After the air blowing operation is completed, the output voltage of the various high-voltage power supplies is raised to the voltage value (setting A) when performing the image forming operation.

[0143] Specifically, in the case of Yes in S309, the control unit 100 changes the output voltage of each high-voltage power supply from the voltage value (setting A) when performing the image forming operation to a predetermined voltage value (setting B) (S610). As a result, the output voltages (charging voltage, developing voltage, and primary transfer voltage) of the charging power supply 600, the developing power supply 601, and the primary transfer power supply 602 drop to the predetermined voltage value (setting B). The voltage value (setting A) and the predetermined voltage value (setting B) when performing the image forming operation are determined in advance and stored in the storage unit (for example, the ROM 102 in FIG. 2) of the control unit 100. The values ​​of the charging voltage, developing voltage, and primary transfer voltage when performing the image forming operation (setting A) may be different from each other. Also, the values ​​of the charging voltage, developing voltage, and primary transfer voltage when performing the air blowing operation (setting B) may be different from each other.

[0144] In the extended feeding device 500, the air blowing operation is started by starting the driving of the fans 511b, 512b of the air blowing units 511A, 512A (6511) based on a command from the control unit 100. When a predetermined time (air blowing time) has elapsed since the driving of the fans 511b, 512b started (Yes in S612), the driving of the fans 511b, 512b is stopped (S613), and the air blowing operation is ended.

[0145] When the air blowing operation is completed, the control unit 100 changes the output voltage of each high voltage power supply from a predetermined voltage value (setting B) to the voltage value (setting A) when performing the image forming operation. As a result, the charging voltage, developing voltage, and primary transfer voltage each rise to the voltage value (setting A) when performing the image forming operation (S614). After the charging voltage, developing voltage, and primary transfer voltage are stabilized at the voltage value (setting A) when performing the image forming operation, the control unit 100 resumes the feeding operation (S306).

[0146] In the third embodiment, the operating state of the image forming unit 201B when the air blowing time is long will be described using the sequence chart of Fig. 15 with reference to the flow of Fig. 14. The operation from the start of a print job (S301) until a predetermined number of sheets S are fed is the same as that of the sequence chart of Fig. 8.

[0147] When a predetermined number of sheets S are fed counting from the start of the print job, the output voltages (charging voltage, developing voltage, and primary transfer voltage) of the various high-voltage power sources are lowered from the voltage value (setting A) when performing the image forming operation to a predetermined voltage value (setting B) (S610). Then, in a state in which the output voltages of the various high-voltage power sources are lowered to the predetermined voltage value (setting B), an air blowing operation is performed for a predetermined air blowing time (Sα, S611 to S613). After the air blowing operation is performed, the output voltages of the various high-voltage power sources are raised again to the voltage value (setting A) when performing the image forming operation (S614). In addition, the feeding motor 520 starts to be driven, and the feeding operation is resumed (S306). Thereafter, every time a predetermined number of sheets S are fed counting from the previous air blowing operation, the output voltages of the various high-voltage power sources are lowered to the predetermined voltage value (setting B), and after the air blowing operation, the output voltages of the various high-voltage power sources are raised to the original voltage value (setting A) repeatedly.

[0148] In this way, in the second embodiment, when the air blowing operation is performed, the voltage value of the charging voltage applied to the charger 213 is lowered compared to the voltage value during image formation. As a result, when the air blowing operation is performed, the charger 213 is continuously applied with the charging voltage of the same voltage value as during image formation, and the increase in the cumulative time during which the charging voltage during image formation is applied to the charger 213 is suppressed relative to the cumulative number of printed sheets of the image forming apparatus. As a result, it is possible to suppress deterioration of the surface of the photosensitive drum 212 due to discharge, and to suppress the promotion of wear of the photosensitive drum 212 due to surface deterioration. In other words, according to this embodiment, it is possible to provide an image forming apparatus that can suppress a decrease in the number of printable sheets of the photosensitive drum.

[0149] In the second embodiment, when the air blowing operation is performed, the rotation of the photosensitive drum 212 is not stopped or decelerated. Therefore, compared to the first embodiment, the downtime of the image forming apparatus 200 due to the execution of the air blowing operation can be shortened, and the productivity of the image forming apparatus 200 can be improved.

[0150] (Modification) In the third embodiment, when the air blowing operation is performed, the rotation of the photosensitive drum 212 may be stopped or the rotation speed of the photosensitive drum 212 may be slowed down. This makes it possible to reduce the amount of rotation of the photosensitive drum 212 while the air blowing operation is performed. In other words, according to this modification, it is possible to provide an image forming apparatus that can further suppress an increase in the amount of wear of the photosensitive member compared to the third embodiment.

[0151] Other Modifications In each of the above-mentioned embodiments, the image forming apparatus 200 capable of performing the air blowing operation has been described as an example of the "adjustment operation", but the "adjustment operation" may be another operation. For example, in an image forming apparatus having a plurality of sheet feeding units, the "adjustment operation" may be an operation of automatically switching the sheet supply source to another sheet feeding unit when the sheets run out in the sheet feeding unit in use during the execution of a print job. In this case, the rotation of the photosensitive drum 212 may be stopped or the charging voltage may be stopped during a waiting time until the sheet feeding unit to which the supply source has been switched is ready to feed. In this case, the predetermined number of sheets is the number of sheets loaded in the sheet feeding unit to be used first. In addition, the "adjustment operation" may be, for example, a cooling period set to prevent overheating of each roller or a feeding motor of the feeding unit.

[0152] In each of the above-described embodiments, a configuration has been exemplified in which the extended feeding device 500 is provided with the air blowing units 511A and 512A as an air handling mechanism. The air handling mechanism is not limited to the extended feeding device 500, and may be provided in another sheet feeding unit (for example, the manual feeding unit 235 or the cassette feeding unit 230 in the image forming apparatus 200 in FIG. 1) provided in the image forming apparatus. In that case, the control described in each embodiment may be applied when the feeding operation is stopped and the air blowing operation is performed during the execution of a print job in which the sheet S is fed from the manual feeding unit 235 or the cassette feeding unit 230 provided with the air handling mechanism.

[0153] In each of the above-described embodiments, a configuration has been described in which a mode in which the photosensitive drum 212 is stopped or the like when the air blowing operation is performed (first mode) and a mode in which the photosensitive drum 212 is not stopped or the like when the air blowing operation is performed (second mode) are selectively performed depending on the length of the air blowing time. However, without being limited to this, for example, the length of the air blowing time may be fixed, and when the air blowing operation is performed, the operation may always be in a mode in which the photosensitive drum 212 is stopped or the like when the air blowing operation is performed.

[0154] In each of the above-described embodiments, the image forming unit 201B, which is an intermediate transfer type tandem type electrophotographic mechanism, has been exemplified as the image forming means. The image forming means is not limited to this, and may be, for example, a direct transfer type in which a toner image formed on a photoconductor is directly transferred to a sheet S without passing through an intermediate transfer body. Also, the image forming means may have only one photoconductor and form a monochrome image using one type of toner.

[0155] (Other embodiments) The present invention can also be realized by a process in which a program for implementing one or more of the functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) that implements one or more of the functions. [Explanation of symbols]

[0156] 100...control means (control unit) / 201B...image forming means (image forming unit) / 212...photosensitive body (photosensitive drum) / 506...feeding means (feeding unit) / 511A, 512A...air handling mechanism (air blowing unit) / 514...sheet support unit (lifter plate) / 610...driving source (drum driving motor)

Claims

1. an image forming unit having a photoreceptor and a drive source for rotating the photoreceptor, and forming an image on a sheet using the photoreceptor; A control means for controlling the driving source; a feeding means for performing a feeding operation of feeding one sheet toward the image forming means; Equipped with the control means is configured to, when executing a job for forming images on a number of sheets greater than a predetermined number, stop the feeding operation after the predetermined number of sheets have been fed by the feeding means, execute an adjustment operation for adjusting conditions related to the feeding of the sheets, and resume the feeding operation after executing the adjustment operation; When the control unit executes the adjustment operation, the control unit executes a mode in which the rotation of the photoconductor is stopped, or the rotation speed of the photoconductor is changed from a first speed, which is the rotation speed of the photoconductor when the image forming unit forms an image on a sheet, to a second speed slower than the first speed.

1. An image forming apparatus comprising:

2. The control unit stops the rotation of the photoconductor when the adjustment operation is performed.

2. The image forming apparatus according to claim 1,

3. When performing the adjusting operation, the control unit changes the rotation speed of the photoconductor from the first speed to the second speed without stopping the rotation of the photoconductor.

2. The image forming apparatus according to claim 1,

4. the mode is a first mode, the control means executes the first mode when the time length of the adjustment operation is a first length, and executes a second mode in which the rotation speed of the photoconductor is maintained at the first speed when executing the adjustment operation when the time length of the adjustment operation is a second length shorter than the first length.

2. The image forming apparatus according to claim 1,

5. the image forming means further includes a charging means for charging the surface of the photoconductor, and a voltage applying means for applying a voltage to the charging means, When performing the adjustment operation, the control means stops application of a voltage to the charging means by the voltage application means, or changes the voltage applied to the charging means by the voltage application means from a first voltage value, which is a value of a voltage applied to the charging means by the voltage application means when the image forming means forms an image on a sheet, to a second voltage value lower than the first voltage value.

2. The image forming apparatus according to claim 1,

6. an image forming means having a photoreceptor, a charging means for charging the surface of the photoreceptor, and a voltage applying means for applying a voltage to the charging means, and forming an image on a sheet using the photoreceptor; A control means for controlling the voltage application means; a feeding means for performing a feeding operation of feeding one sheet toward the image forming means; Equipped with the control means is configured to, when executing a job for forming images on a number of sheets greater than a predetermined number, stop the feeding operation after the predetermined number of sheets have been fed by the feeding means, execute an adjustment operation for adjusting conditions related to the feeding of the sheets, and resume the feeding operation after executing the adjustment operation; When performing the adjustment operation, the control means stops application of a voltage to the charging means by the voltage application means, or executes a mode in which the voltage applied by the voltage application means to the charging means is changed from a first voltage value, which is a value of a voltage applied by the voltage application means to the charging means when the image forming means forms an image on a sheet, to a second voltage value lower than the first voltage value.

1. An image forming apparatus comprising:

7. When the adjustment operation is performed, the control unit stops the application of the voltage to the charging unit by the voltage application unit.

7. The image forming apparatus according to claim 6,

8. When performing the adjusting operation, the control unit changes the voltage applied to the charging unit by the voltage application unit from the first voltage value to the second voltage value.

7. The image forming apparatus according to claim 6,

9. the mode is a first mode, the control means executes the first mode when performing the adjustment operation if the time length of the adjustment operation is a first length, and executes the second mode in which the voltage applied by the voltage application means to the charging means is maintained at the first voltage value when performing the adjustment operation if the time length of the adjustment operation is a second length shorter than the first length.

7. The image forming apparatus according to claim 6,

10. a sheet support portion that supports a sheet fed by the feeding means; an air handling mechanism that performs an air blowing operation of blowing air onto the sheet stack supported by the sheet support section to handle the sheets; Further comprising: The adjustment operation is the air blowing operation.

10. The image forming apparatus according to claim 1, wherein the first and second electrodes are arranged in a first direction.

11. The image forming apparatus further includes an environment detection unit that detects an environmental condition of an environment in which the image forming apparatus is installed, The control means changes the duration of the air blowing operation in response to the environmental conditions detected by the environmental detection means.

11. The image forming apparatus according to claim 10.

12. the environment detection unit detects at least one of a temperature and a humidity of an environment in which the image forming apparatus is installed; 12. The image forming apparatus according to claim 11.

13. the control unit repeats, during execution of the job, performing the air blowing operation once each time the feeding unit feeds the predetermined number of sheets.

11. The image forming apparatus according to claim 10.

14. the image forming unit further includes a cleaning unit disposed in contact with the surface of the photoreceptor, the cleaning unit rubbing the surface as the photoreceptor rotates to remove foreign matter adhering to the surface, 10. The image forming apparatus according to claim 1, wherein the first and second electrodes are arranged in a first direction.

Images