Sheet feeding device and image forming device

Abstract

To enable the feeding of even sheets having high inter-sheet adhesion, while reducing sheet skewing.SOLUTION: A sheet feeding device comprises: a sheet feeding part for performing feeding operation to feed an uppermost sheet of a sheet bundle supported by a sheet support part; an air separating part for performing a blowing operation to separate the sheets by blowing air to the side of the sheet bundle supported by the sheet support part; and a control part. The control part, during execution of a job for feeding the sheets, makes the air separating part perform the blowing operation in a state where a feeding rotor is brought into contact with the uppermost sheet of the sheet bundle supported by the sheet support part (S1, S2). After the blowing operation by the air separating part is performed, feeding processes (S1-S5) are executed in which a drive part is driven in a state where the blowing operation is stopped and the feeding operation by the sheet feeding part is performed.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a sheet feeding device and an image forming apparatus that perform a blowing operation for blowing air to separate sheets. [Background technology]

[0002] For example, image forming devices such as copiers, facsimiles, and printers are provided with sheet feeding devices such as a feeding cassette and a feeding deck for setting a stack of sheets to be supplied to an image forming section where an image is formed. In recent years, there has been an increasing demand for forming images on various types of sheets, and sheets with smooth surfaces such as coated paper are sometimes used as recording materials. When such a stack of sheets with a smooth surface is set in a sheet feeding device, the sheets may adhere closely to each other, making it difficult to feed the sheets. For this reason, a device has been proposed that blows air onto the stack of sheets to lift them up and handle the sheets (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-256819 A Summary of the Invention [Problem to be solved by the invention]

[0004] In a configuration that includes a mechanism for blowing air onto a sheet stack, such as the image forming apparatus described in Patent Document 1, a sheet is generally fed from a sheet feeding device while the air is being blown onto the sheet. However, when the sheet is fed while air is being blown onto the sheet, the sheet is raised, and the edge of the sheet is likely to bend. For this reason, even if the position of the sheet in the width direction is restricted by, for example, a restricting plate, the sheet is likely to bend and become skewed when a force is generated to rotate the sheet.

[0005] Therefore, an object of the present invention is to provide a sheet feeding device and an image forming apparatus that are capable of feeding even sheets having high adhesion to each other while reducing sheet skew. [Means for solving the problem]

[0006] One aspect of the present invention is a sheet feeding device comprising: a sheet supporting section that supports a sheet stack; a feeding rotor that is movable between an abutment position where it abuts against the top sheet of the sheet stack supported by the sheet supporting section and a separation position where it is separated from the top sheet of the sheet stack supported by the sheet supporting section; and a drive section that drives the feeding rotor, and the sheet feeding section drives the drive section to perform a feeding operation to feed the top sheet of the sheet stack supported by the sheet supporting section; an air handling section that performs a blowing operation to blow air against the sides of the sheet stack supported by the sheet supporting section to separate the sheets; and a control section that performs a feeding process in which, during the execution of a job to feed sheets, the air handling section performs the blowing operation with the feeding rotor abutting the top sheet of the sheet stack supported by the sheet supporting section, and then drives the drive section with the blowing operation stopped to perform the feeding operation by the sheet feeding section. Effect of the Invention

[0007] According to the present invention, it is possible to feed sheets even when the sheets are closely adhered to each other, and it is also possible to reduce skew of the sheets. [Brief description of the drawings]

[0008] [Figure 1] 1 is a diagram showing a schematic configuration of an image forming apparatus according to a first embodiment. [Diagram 2] 2 is a block diagram showing a control system of the image forming apparatus according to the first embodiment. FIG. [Diagram 3] FIG. 2 is a schematic diagram showing a configuration of a manual feed section according to the first embodiment. [Figure 4]1A is a schematic side view illustrating the position of the pickup roller in a state in which the manual feed section according to the first embodiment is not transporting a sheet placed on a feed tray; FIG. 1B is a schematic side view illustrating a state in which the pickup roller comes into contact with the sheet as feeding of the sheet placed on the feed tray begins; FIG. 1C is a schematic side view illustrating a state in which the air blowing section is driven to blow air onto the sheet stack when the pickup roller comes into contact with the sheet; and FIG. 1D is a schematic side view illustrating a state in which the pickup roller and the feed roller are driven to rotate and feeding of the sheet begins. [Diagram 5] 5 is a flowchart showing a sheet feeding control according to the first embodiment. [Figure 6] 10 is a flowchart showing a sheet feeding control according to the second embodiment. [Figure 7] FIG. 11 is a diagram illustrating a part of a control sequence of an image forming apparatus according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] <First embodiment> A first embodiment of the present invention will be described in detail below with reference to the drawings. First, an image forming apparatus 201 according to the present invention will be described with reference to Fig. 1. Fig. 1 is a cross-sectional view showing a schematic configuration of the image forming apparatus 201 according to the first embodiment.

[0010] [General configuration of image forming device] As shown in Fig. 1, the image forming apparatus 201 of the first embodiment is a tandem type intermediate transfer type laser beam printer that utilizes an electrophotographic process. In Fig. 1, 201 is an image forming apparatus, 201A is an image forming apparatus main body, and 201B is an image forming section that forms an image on a sheet. 202 is an image reading device that is installed substantially horizontally above the image forming apparatus main body 201A, and a discharge space V for discharging sheets is formed between this image reading device 202 and the image forming apparatus main body 201A. An operation unit 730 composed of a touch panel or the like capable of displaying a screen is disposed above the image forming apparatus main body 201A.

[0011] The image forming section 201B, which is an image forming means, is of a four-drum full-color type. The image forming section 201B includes a laser scanner 210 as an exposure means, 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). Here, each process cartridge 211 includes a photosensitive drum 212 as an image carrier, a charger 213 as a charging means, and a developer 214 as a developing means. In addition, the image forming section 201B includes an intermediate transfer unit 201C arranged above the process cartridge 211, and a fixing section 201E. Incidentally, 215 is a toner cartridge for supplying toner to the developer 214.

[0012] The intermediate transfer unit 201C includes an intermediate transfer belt 216 wound around a drive roller 216a and a tension roller 216b. A primary transfer roller 219 is provided on the inner side of the intermediate transfer belt 216, and contacts the intermediate transfer belt 216 at a position facing the photosensitive drum 212. The intermediate transfer belt 216 is rotated in the direction of the arrow by a drive roller 216a driven by a drive unit (not shown).

[0013] Then, the negative color toner images on the photosensitive drums are sequentially transferred onto the intermediate transfer belt 216 by the primary transfer roller 219. A secondary transfer roller 217 that transfers the color image formed on the intermediate transfer belt 216 onto the sheet P is provided at a position facing the driving roller 216a of the intermediate transfer unit 201C. A secondary transfer section 201D is formed between the intermediate transfer belt 216 and the secondary transfer roller 217. Furthermore, a fixing section 201E having a pressure roller 220a and a heating roller 220b is provided above the secondary transfer roller 217. A first discharge roller pair 225a, a second discharge roller pair 225b, and a double-sided reversing section 201F are provided at the upper left of the fixing section 201E. The double-sided reversing section 201F is provided with a reversing roller pair 222 that can rotate forward and backward, a re-conveying path R that conveys the sheet with an image formed on one side to the image forming section 201B again, and the like.

[0014] A sheet feeding unit 230 that feeds the set sheets S to the image forming section 201B is provided at the bottom of the image forming apparatus main body 201A. The sheet feeding unit 230 includes a feeding cassette 1 that stores sheets, and a sheet feeding section 5 that feeds the sheets S stored in the feeding cassette 1. The sheet feeding section 5 includes a pickup roller 2, and a feed roller 3 and a retard roller as a separation means that separates the sheets S that have been fed from the pickup roller 2 and fed in a multi-feed state.

[0015] 1 of the image forming apparatus main body 201A is provided with a manual feed section 235 that feeds the set sheet S to the image forming section 201B. The manual feed section 235 has a feed tray 6 that supports the sheet S. Similarly to the sheet feeding unit 230, the manual feed section 235 has a pickup roller 502 that is a sheet feeding means. The manual feed section 235 also has a feed roller 503 and a retard roller 504 that are separation means for separating the sheet S fed from the pickup roller 502.

[0016] Next, a description will be given of the image forming operation of the image forming apparatus 201. First, the image forming apparatus 201 acquires image information of an original. The image information of the original is acquired by reading it with the image reading apparatus 202 or by receiving print image data output from a host device 900 (see FIG. 2) connected to the control unit 100 (see FIG. 2) of the image forming apparatus 201.

[0017] The image information acquired by the image forming apparatus 201 is subjected to image processing, converted into an electric signal, and transmitted to a laser scanner 210 of the image forming section 201B. In the image forming section 201B, the surface of the photosensitive drum 212, the surface of which is uniformly charged to a predetermined polarity and potential by a charger 213, is sequentially exposed to laser light. As a result, electrostatic latent images of yellow, magenta, cyan, and black are sequentially formed on the photosensitive drum of each process cartridge 211, respectively.

[0018] Thereafter, the electrostatic latent images are developed and visualized with toner of each color, and the toner images of each color on each photoconductor drum are transferred in order onto the intermediate transfer belt 216 in a superimposed manner by a primary transfer bias applied to the primary transfer roller 219. As a result, a toner image is formed on the intermediate transfer belt 216.

[0019] On the other hand, the sheet S fed by the feed roller 3 of the sheet feeding unit 230 is conveyed to a pair of registration rollers (hereinafter referred to as the registration roller pair) 240 consisting of a drive roller and a driven roller. At this time, the driving of the registration roller pair 240 is stopped, and the leading edge of the sheet S is abutted against the registration roller pair 240. As a result, the leading edge of the sheet S is made to follow the registration roller pair 240. Thereafter, as the sheet S continues to be conveyed by the feed roller 3, a flexure (loop) is formed in the sheet S, and when a predetermined loop amount is reached, the registration roller pair 240 is driven. As a result, the skew of the sheet S is corrected by the registration roller pair 240, and the sheet S with the skew corrected is conveyed to the secondary transfer portion 201D by the registration roller pair 240. Subsequently, in the secondary transfer portion 201D, the toner images are transferred collectively onto the sheet S by a secondary transfer bias applied to the secondary transfer roller 217. The sheet S onto which the toner image has been transferred is then conveyed to a fixing section 201E, where the toner of each color is melted and mixed by heat and pressure, and is fixed onto the sheet S as a color image.

[0020] Thereafter, the sheet S on which the image has been fixed is discharged to the discharge space V by a first discharge roller pair 225a and a second discharge roller pair 225b provided downstream of the fixing section 201E, and is stacked on a stacking section 223 formed on the bottom surface of the discharge space V. When images are formed on both sides of the sheet S, after the images are fixed, the sheet S is transported to a re-conveying path R by a reversing roller pair 222, and is transported again to the image forming section 201B.

[0021] [Configuration of the control system of the image forming device] Next, the configuration of a control system in the image forming apparatus 201 will be described with reference to Fig. 2. Fig. 2 is a block diagram showing the control system of the image forming apparatus 201 according to the first embodiment.

[0022] The control unit 100 according to the first embodiment is provided in, for example, an image forming apparatus 201, and is configured to include a CPU 101, a ROM 102, and a RAM 103. The control unit 100 is a control means for controlling the image forming apparatus 201. The control unit 100 is connected to a host device 900 and an operation unit 730, and transmits and receives information therebetween. The control unit 100 also performs signal processing and sequence control for various process devices. Here, the host device 900 is an external device such as a personal computer, an image scanner, or a facsimile machine.

[0023] The control unit 100 is connected to fan motors 15a and 15b (described later), a sheet presence / absence detection sensor 17, a drive unit and motor for driving the pickup roller 502 and the feed roller 503, and a paper feed motor 520 serving as a first motor, etc. The control unit 100 is also connected to a conveying motor 521 serving as a second motor for driving the pull-out roller 506, etc.

[0024] The paper feed motor 520 is driven to rotate in a CW direction (first direction) to drive and rotate the pickup roller 502 and the feed roller 503. The paper feed motor 520 is also driven to rotate in a CCW direction (second direction) opposite to the CW direction to move the pickup roller 502 between two positions: a contact position where the pickup roller 502 contacts the sheet S, and a separated position where the pickup roller 502 and the sheet S do not contact each other.

[0025] The paper feed motor 520 is connected to the pickup roller 502 and the feed roller 503 via a drive mechanism 520a. The drive mechanism 520a has a drive gear that transmits a drive force to rotate the pickup roller 502 and the feed roller 503 in a sheet feeding direction. The drive mechanism 520a also has a movement mechanism that moves (raises and lowers) the pickup roller 502 between two positions, the contact position and the separation position. The drive mechanism 520a also has a one-way clutch that transmits a drive force to the drive gear and transmits power to the movement mechanism when the paper feed motor 520 drives forward in the CW direction. The drive mechanism 520a also has a one-way clutch that transmits a drive force to the movement mechanism and transmits power to the drive gear when the paper feed motor 520 drives reversely in the CCW direction.

[0026] In the manual feed section 235, the feed motor 520 is driven in the forward direction CW to transmit a driving force to the pickup roller 502 and the feed roller 503 to rotate in the direction of feeding the sheet. Also, in the manual feed section 235, the feed motor 520 is driven in the reverse direction CCW to move the pickup roller 502 between the two positions, the contact position and the separation position.

[0027] CPU 101 of control unit 100 detects that pickup roller 502 is located at the contact position from a signal output when a home position detection sensor provided in the movement mechanism turns ON. CPU 101 also drives paper feed motor 520 in the reverse direction until a sufficient time has elapsed since the home position detection sensor turned ON for pickup roller 502 to move to the separated position, thereby moving pickup roller 502 to the separated position. This will be described in more detail later.

[0028] [Manual feed section configuration] Next, the manual feed unit 235 as a sheet feeding device will be described in detail with reference to Figures 1, 3, and 4. Figure 3 is a schematic top view of the manual feed unit 235 of the first embodiment.

[0029] 3, the manual feed section 235 includes a feed tray 6 serving as a sheet support section and a manual feed tray, and a first sheet feed section 500 that performs a feeding operation. The first sheet feed section 500 includes a pickup roller 502 serving as a feeding rotor, and a feed roller 503 and a retard roller 504 that are separation means for separating the sheet S fed from the pickup roller 502.

[0030] In the manual feed section 235, a pull-out roller 506 is disposed downstream of the feed roller 503 and the retard roller 504 in the conveying direction Y1 of the sheet S as a second sheet feed section.

[0031] The manual feed section 235 is provided with a sheet presence / absence detection sensor 17 which is disposed on the feed tray 6 and detects whether or not a sheet S is placed on the feed tray 6. The manual feed section 235 is provided with a feed detection sensor 505 which is disposed at a position between the feed roller 503 and the retard roller 504, and the pull-out roller 506 in the conveying direction Y1 of the sheet S and detects the passage of the sheet S.

[0032] The feeding tray 6 is provided with side end regulating plates 14a and 14b as regulating parts for regulating the position in a direction (sheet width direction) perpendicular to the conveying direction Y1 of the sheet S. The side end regulating plates 14a and 14b are provided with air blowing parts 150a and 150b as air handling parts, respectively.

[0033] The air blowing section 150a of the side end regulating plate 14a has a fan 151a driven by a fan motor 15a (see FIG. 2) and a blowing nozzle 16a that guides the air blown from the fan 151a and blows it from the side of the sheet stack. The blowing nozzle 16a has an outlet 160a through which the air blown from the fan 151a blows out on a contact surface 140a of the side end regulating plate 14a that contacts the sheet stack.

[0034] Similarly, the air blowing section 150b of the side end regulating plate 14b has a fan 151b driven by a fan motor 15b (see FIG. 2) and a blowing nozzle 16b that guides the air blown from the fan 151b and blows it from the side of the sheet stack. The blowing nozzle 16b has an outlet 160b through which the air blown from the fan 151b blows out on a contact surface 140b of the side end regulating plate 14b that contacts the sheet stack.

[0035] In the first embodiment, the fan motors 15a and 15b are controlled by PWM control, and φ97 mm blower fans are used for the fans 151a and 151b. In the manual feed section 235, during the air blowing operation, the fan motors 15a and 15b are PWM controlled at a predetermined duty ratio (for example, 40%) as the PWM duty ratio to blow air.

[0036] In the feeding tray 6, air from fan motors 15a and 15b is blown toward the ends of the sheets S as indicated by arrows A1 and A2, so that the upper sheets of the sheet stack are lifted, and the adhesion between the sheets is reduced.

[0037] Fig. 4(a) is a schematic side view illustrating the position of the pickup roller 502 in a state in which the manual feed section 235 is not conveying the sheet S placed on the feed tray 6. As shown in Fig. 4(a), in the manual feed section 235, when the sheet S is not being conveyed, the pickup roller 502 is separated from the feed tray 6 and the pickup roller 502 and the sheet S are not in contact with each other. This allows the manual feed section 235 to smoothly load a sheet stack onto the feed tray 6.

[0038] 4B is a schematic side view showing a state in which the pickup roller 502 comes into contact with the sheet S placed on the feed tray 6 as a result of the start of conveyance of the sheet S. As shown in FIG. 4B, in the manual feed section 235, the pickup roller 502 is rotated around the axis of the feed roller 503, and the pickup roller 502 comes into contact with the sheet S placed on the feed tray 6.

[0039] As described above, the movement operation to the contact position where the pickup roller 502 contacts the sheet S is performed using the driving force of the sheet feed motor 520 (see FIG. 2). In the manual feed section 235, the sheet feed motor 520 is driven to rotate forward in the CW direction (first direction), so that the pickup roller 502 and the feed roller 503 are rotated via the drive mechanism 520a in a direction capable of conveying the sheet S in the conveying direction Y1. In the manual feed section 235, the sheet feed motor 520 is driven to rotate reversely in the CCW direction (second direction), so that the pickup roller 502 is lifted and lowered in the Z direction via the drive mechanism 520a. When the sheet feed motor 520 is driven reversely, the pickup roller 502 is lifted and lowered in the Z direction between two positions, a contact position where the pickup roller 502 contacts the sheet S, and a separated position where the pickup roller 502 does not contact the sheet S.

[0040] Fig. 4(c) is a schematic side view showing a state in which fan motors 15a and 15b are driven to blow air onto the sheet stack with pickup roller 502 in contact with sheets S. As shown in Fig. 4(c), in manual feed section 235, air is blown by air blowing sections 150a and 150b with the end of sheets S being sandwiched between pickup roller 502 and feed tray 6.

[0041] As a result, in the manual feed section 235, the adhesion force between the sheets can be reduced while minimizing the variation caused to the sheets by the air blowing.

[0042] Fig. 4(d) is a schematic side view showing a case where pickup roller 502 and feed roller 503 are rotationally driven and conveyance of sheet S is started. As shown in Fig. 4(d), in manual feed section 235, after air blowing by air blowing sections 150a and 150b stops, conveyance of sheet S is started by rotationally driving pickup roller 502. In manual feed section 235, sheet S sent out from pickup roller 502 is sandwiched and conveyed by feed roller 503 and retard roller 504, so that sheet S is separated from the sheet stack and conveyed.

[0043] This makes it possible for the manual feed section 235 to suppress a situation in which the sheet S is deflected by the air blowing sections 150a and 150b, and the sheet S is turned and skewed when being conveyed.

[0044] [Control flow of manual feed section] 5 is a flowchart showing a control process executed by the CPU 101 of the control unit 100 when feeding sheets S from the manual feeding unit 235 in the image forming apparatus 201 of the first embodiment. The control process shown in FIG. 5 is started when the CPU 101 issues a command to start a job to feed a required number of sheets S as a predetermined number from a sheet stack supported on the feeding tray 6.

[0045] First, CPU 101 lowers pickup roller 502 to the contact position and brings pickup roller 502 into contact with sheet S (S1). In this process, CPU 101 drives paper feed motor 520 in the reverse direction until a home position detection sensor provided in the moving mechanism of drive mechanism 520a is turned ON, and lowers pickup roller 502 from the separated position to the contact position where it comes into contact with sheet S. By executing the process of step S1, manual feed unit 235 changes from the state shown in FIG. 4(a) to the state shown in FIG. 4(b).

[0046] Next, CPU 101 causes air blowing units 150a and 150b to blow air (S2). In this process, CPU 101 drives fan motors 15a and 15b to blow air using air blowing units 150a and 150b. When air blowing units 150a and 150b blow air while pickup roller 502 is in the contact position, manual feed unit 235 changes from the state shown in FIG. 4(b) to the state shown in FIG. 4(c).

[0047] Next, CPU 101 determines whether or not the blowing time has elapsed since air blowing units 150a and 150b started blowing air (S3). If CPU 101 determines that the blowing time has not elapsed (No) in this process, CPU 101 returns to step S2 and repeats the processes of steps S2 and S3 until the blowing time has elapsed.

[0048] The spraying time is determined in advance by the CPU 101 as an appropriate time based on media characteristics such as the basis weight and surface properties of the sheet S being fed, and environmental information such as room temperature and humidity in the environment in which the image forming apparatus 201 operates.

[0049] When it is determined in the process of step S3 that the blowing time has elapsed (Yes), CPU 101 stops the air blowing by air blowing units 150a and 150b (S4). Next, CPU 101 performs a feeding operation of sheet S by driving paper feed motor 520 to rotate in the normal direction and rotating pickup roller 502 and feed roller 503 in a direction that allows sheet S to be conveyed in conveyance direction Y1 (S5). By performing the feeding operation of sheet S after air blowing by air blowing units 150a and 150b is completed, manual feed unit 235 changes from the state shown in FIG. 4(c) to the state shown in FIG. 4(d).

[0050] By executing the processes of steps S4 and S5, in the manual feed section 235, after the air blowing is stopped, the sheets S that were in a floating state return to the state of a stack before floating as the air between the sheets is released. At this time, the adhesion between the sheets remains reduced by the air blowing operation. Therefore, in the manual feed section 235, it is possible to prevent, for example, the pickup roller 502 from slipping and making it impossible to convey the sheets, and it is possible to feed even sheets that have a high adhesion between them. The processes of steps S1 to S5 constitute the feeding process in the first embodiment.

[0051] Next, CPU 101 determines whether or not the required number of sheets has been fed (S6). In this process, CPU 101 determines whether or not the required number of sheets has been fed based on the number of sheets detected to have passed by feed detection sensor 505. If CPU 101 determines in the process of step S6 that the required number of sheets has not been fed (No), CPU 101 returns the process to step S5 and repeats the processes of steps S5 and S6 until the required number of sheets has been fed.

[0052] When it is determined in the process of step S6 that the required number of sheets have been fed (Yes), CPU 101 determines that the job of feeding the required number of sheets S has ended and the job is no longer being executed (not being executed). CPU 101 reversely drives paper feed motor 520 to raise pickup roller 502 from the contact position where it contacts sheets S to a separated position where it does not contact sheets S (S7). Then, CPU 101 completes the feeding operation of sheets S by manual feed unit 235.

[0053] In this way, the manual feed unit 235 of the first embodiment is configured to maintain the pickup roller 502 at the abutment position during execution of a job. As a result, the manual feed unit 235 can feed sheets sequentially from the sheet stack by maintaining the pickup roller 502 at the abutment position and rotating it until the required number of sheets are fed and the job is completed.

[0054] In addition, by positioning the pickup roller 502 at the separated position during non-execution when a job is not being executed, the manual feed section 235 can prevent the pickup roller 502 from interfering when placing a sheet on the feed tray 6.

[0055] As described above, the manual feed unit 235 of the first embodiment can feed sheets having a smooth surface such as coated paper by separating the top several to several tens of sheets in a sheet stack using an air blowing operation to reduce adhesion. Also, when performing the air blowing operation, the manual feed unit 235 brings the pickup roller 502 into contact with the leading edge of the sheet.

[0056] This makes it possible for the manual feed section 235 to suppress a situation in which the sheet S is deflected by the air blowing sections 150a and 150b, and the sheet S is turned and skewed when being conveyed.

[0057] Then, since the sheet feeding operation is performed after the air blowing operation is stopped, the amount of skew of the sheet fed from the manual feeding unit 235 can be improved compared to the case where the feeding operation is performed while the air blowing operation is being performed. Therefore, when correcting the skew of the sheet at the registration roller pair 240, the amount of skew correction required is small, so that the variation in the position of the sheet conveyed to the secondary transfer unit 201D can be reduced and the printing precision (quality) can be improved.

[0058] <Second embodiment> Next, an image forming apparatus 201 according to a second embodiment will be described. The image forming apparatus 201 according to the second embodiment is configured to be able to move the pickup roller 502 to a separated position during execution of a job for feeding a required number of sheets S from a sheet stack supported by a feeding tray 6. In this respect, the image forming apparatus 201 according to the second embodiment differs from the first embodiment described above. Since the other configurations are similar to those of the first embodiment, the same reference numerals are used for components common to the first embodiment, and the same step numbers are used for control processes common to the first embodiment, and description thereof will be omitted.

[0059] [Control flow of manual feed section] 6 is a flowchart showing a control process executed by the CPU 101 of the control unit 100 when feeding sheets S from the manual feeding unit 235 in the image forming apparatus 201 of the second embodiment. The control process shown in FIG. 6 is started when the CPU 101 issues a command to start a job to feed a required number of sheets S from a sheet stack supported on the feeding tray 6.

[0060] After executing the process of step S5, CPU 101 judges whether the leading edge of sheet S has been fed to a first position (S11). In the second embodiment, the first position is a position that is a first distance (e.g., 10 mm) downstream in the conveying direction of sheet S from pull-out roller 506 located downstream of feed roller 503 in the conveying direction of sheet S. CPU 101 determines whether the leading edge of sheet S has reached the first position based on a calculation based on the speed at which sheet S is fed and the time that has elapsed since feed detection sensor 505 located between feed roller 503 and pull-out roller 506 detected the leading edge of sheet S.

[0061] In the process of step S11, if it is determined that the leading edge of the sheet S has not been fed to the first position (No), the CPU 101 returns the process to step S5. On the other hand, in the process of step S11, if it is determined that the leading edge of the sheet S has been fed to the first position (Yes), the CPU 101 advances the process to step S12.

[0062] In the process of step S12, CPU 101 drives paper feed motor 520 in the reverse direction to raise pickup roller 502 from the contact position where it contacts sheet S to the separated position where it does not contact sheet S (S12). As described above, in manual feed section 235, paper feed motor 520 is driven in the reverse direction to move pickup roller 502 between the contact position and the separated position via the drive train section. Furthermore, pickup roller 502 and feed roller 503 are configured to be rotated in a direction in which sheet S can be conveyed in conveyance direction Y1 by paper feed motor 520 being driven in the forward direction.

[0063] Therefore, in the manual feed unit 235, the process of step S12 is executed and the feed motor 520 is driven in the reverse direction, so that the pickup roller 502 moves to the separated position and separates from the sheet S. Also, in the manual feed unit 235, the feed motor 520 is driven in the reverse direction, so that the feed roller 503 is not rotated in a direction capable of conveying the sheet S in the conveying direction Y1.

[0064] However, in the manual feed section 235, the sheet S has already reached the pull-out roller 506, and the pull-out roller 506 is rotated by a conveyance motor 521 separate from the feed motor 520. Therefore, in the manual feed section 235, the process of step S12 is executed, and even in a state in which the feed motor 520 is driven in the reverse direction, the conveyance of the sheet S can be continued by the pull-out roller 506.

[0065] Next, CPU 101 determines whether the trailing end of sheet S has been fed to a second position (S13). In the second embodiment, the second position is a position that is a second distance (e.g., 10 mm) downstream in the conveying direction of sheet S from feed roller 503. CPU 101 determines whether the trailing end of sheet S has reached the second position based on the time that has elapsed since the start of feeding of sheet S and the length of sheet S in the conveying direction Y1.

[0066] In the process of step S13, if it is determined that the trailing end of the sheet S has not been fed to the second position (No), the CPU 101 repeats the process of step S13 while continuing the feeding operation until the trailing end of the sheet S reaches the second position. On the other hand, in the process of step S13, if it is determined that the trailing end of the sheet S has been fed to the second position (Yes), the CPU 101 advances the process to step S14.

[0067] In the process of step S14, CPU 101 determines whether or not the feeding of the required number of sheets has been completed (S14). In this process, CPU 101 determines whether or not the feeding of the required number of sheets has been completed based on the number of sheets detected to have passed by feeding detection sensor 505.

[0068] When it is determined in the process of step S14 that the feeding of the required number of sheets has not been completed (No), CPU 101 determines that the job of feeding the required number of sheets S has ended, and completes the feeding operation of sheets S by manual feed unit 235. In manual feed unit 235, by executing the process of step S12, pickup roller 502 is positioned at the separated position at the time the job is completed. In other words, in manual feed unit 235 of the second embodiment, pickup roller 502 is positioned at the separated position when a job is not being executed (when not being executed).

[0069] On the other hand, if it is determined in the process of step S14 that the required number of sheets has not been fed (No), CPU 101 lowers pickup roller 502 to the contact position and contacts pickup roller 502 with the uppermost sheet of the sheet stack (S15). Then, CPU 101 returns the process to step S5.

[0070] By CPU 101 returning the process to step S5 after executing the process of step S15, manual feed unit 235 repeats the processes of steps S5 to S15 until the required number of sheets S set in the job is fed. That is, manual feed unit 235 moves pickup roller 502 from the contact position to the separated position each time a sheet becomes ready for feeding by pull-out roller 506 until the required number of sheets S is fed from the sheet stack supported by feed tray 6. Also, manual feed unit 235 moves pickup roller 502, which is located at the separated position, to the contact position before starting to feed a new sheet from the sheet stack.

[0071] As a result, the manual feed section 235 can prevent the pickup roller 502 from leaving marks on the sheets by keeping the pickup roller 502 in contact with the sheet stack supported by the feed tray 6 until the required number of sheets specified in the job is fed.

[0072] [Control sequence] FIG. 7 is a diagram illustrating a part of a control sequence in the image forming apparatus 201 according to the second embodiment.

[0073] 7, in manual feed unit 235, at time t0 when a job is started, sheet feed motor 520 starts reverse driving at voltage V2, and pickup roller 502 starts moving from the separated position toward the contact position. In manual feed unit 235, pickup roller 502 reaches the contact position at time t1. CPU 101 detects that pickup roller 502 has contacted the contact position using a signal output from a home position detection sensor provided in the moving mechanism of drive mechanism 520a. When CPU 101 detects that pickup roller 502 has contacted the contact position, it stops reverse driving of sheet feed motor 520.

[0074] In the manual feed section 235, at time t2 when time T10 has elapsed since time t1 when the pickup roller 502 abuts on the abutment position, the fan motors 15a and 15b are driven to start the air blowing operation by the air blowing sections 150a and 150b. In the manual feed section 235, during the air blowing operation, the fan motors 15a and 15b are PWM-controlled at a predetermined ratio (e.g., 40%) as the PWM duty ratio to blow air. The air blowing operation is performed until time T11 (e.g., 10 seconds) has elapsed as the blowing time.

[0075] In the manual feed section 235, the air blowing operation by the air blowing sections 150a and 150b is started at time t2, and the air blowing operation by the air blowing sections 150a and 150b is ended at time t3 when time T11 has elapsed. In the manual feed section 235, at time t5 when time T12 has elapsed from time t3 when the air blowing operation is ended, the uppermost sheet S of the sheet stack supported by the feed tray 6 is started to be fed. At time t5, in the manual feed section 235, the feed motor 520 is started to be driven in the forward direction by the voltage V1, and the conveyance motor 521 is also started to be driven to rotate by the voltage V1. As a result, in the manual feed section 235, the pickup roller 502 of the first sheet feed section 500 starts to feed the uppermost sheet S of the sheet stack supported by the feed tray 6.

[0076] In image forming apparatus 201, exposure of the surface of photoconductor drum 212 by laser scanner 210 starts at time t4 from time t3 when the air blowing operation ends until time t5 when the feeding operation by first sheet feeding unit 500 starts. In other words, image forming apparatus 201 performs air blowing operation by air blowing units 150a and 150b before exposure of the surface of photoconductor drum 212 by laser scanner 210 at which image forming unit 201B starts image formation from acquired image information.

[0077] With this configuration, the manual feed section 235 of the second embodiment can prevent defects in image formation by the image forming section 201B caused by vibrations of the feed tray 6 generated by the air blowing operations of the air blowing sections 150a and 150b.

[0078] In the manual feed section 235, at time t7 when time T13 has elapsed since time t6 when the feed detection sensor 505 detects the leading edge of the sheet S, the leading edge of the sheet S reaches a first position downstream of the pull-out roller 506 in the conveying direction. In the manual feed section 235, the forward rotation drive of the sheet feed motor 520 at voltage V1 is stopped, and at time t8 when time T14 has elapsed since time t7, reverse drive is started at voltage V2, and the pickup roller 502 starts to move from the contact position to the separation position. In the manual feed section 235, at time t9 when time T15 has elapsed since time t8, the CPU 101 determines that the pickup roller 502 has reached the separation position based on the elapsed time, and the reverse drive of the sheet feed motor 520 is stopped.

[0079] In the manual feed section 235, the conveying motor 521 continues to be rotated at the voltage V1 from time t7 to time t9. Therefore, in the manual feed section 235, even after time t7 when the forward rotation of the feed motor 520 stops, the sheet S continues to be fed by the pull-out roller 506 which is rotated by the conveying motor 521.

[0080] As described above, the manual feed unit 235 of the second embodiment can feed sheets having a smooth surface such as coated paper by separating the top several to several tens of sheets in a sheet stack using an air blowing operation to reduce adhesion. Also, when performing the air blowing operation, the manual feed unit 235 brings the pickup roller 502 into contact with the leading edge of the sheet.

[0081] This makes it possible for the manual feed section 235 to suppress a situation in which the sheet S is deflected by the air blowing sections 150a and 150b, and the sheet S is turned and skewed when being conveyed.

[0082] In addition, since the sheet feeding operation is performed after the air blowing operation is stopped, the amount of skew of the sheet fed from the manual feeding unit 235 can be improved compared to the case where the feeding operation is performed while the air blowing operation is being performed. Therefore, when correcting the skew of the sheet at the registration roller pair 240, the amount of skew correction required is small, so that the variation in the position of the sheet conveyed to the secondary transfer unit 201D can be reduced and the printing precision (quality) can be improved.

[0083] Then, the manual feed section 235 of the second embodiment moves the pickup roller 502 from the contact position to the separated position when the sheet S to be fed reaches the pull-out roller 506 located downstream in the conveying direction from the first sheet feeding section 500. As a result, the manual feed section 235 can prevent the pickup roller 502 from leaving a mark on the sheet by keeping the pickup roller 502 in contact with the sheet stack supported by the feeding tray 6 until the required number of sheets specified in the job are fed.

[0084] <Other embodiments> In the above-described first and second embodiments, the sheet feeding control in the manual feeding section 235 having the air blowing sections 150a and 150b has been described. However, the present invention is not limited to this, and the sheet feeding control according to the first and second embodiments may be performed in a sheet feeding unit 230 having a feeding cassette 1, or in a feeding deck connectable to the image forming apparatus 201 having an air blowing section, or the like. In addition, when the sheet feeding control according to the first and second embodiments is performed in the sheet feeding unit 230, the sheet feeding control may be performed in any stage in the vertical direction. In other words, the sheet supporting section that supports the sheet stack may have any configuration.

[0085] In the first and second embodiments, the first sheet feeding unit 500 moves the pickup roller 502 up and down by driving the feed motor 520, which rotates the pickup roller 502 and the feed roller 503, in the reverse direction, but is not limited to this. The first sheet feeding unit 500 may be configured to move the pickup roller 502 between the contact position and the separated position using a different actuator such as a motor or a solenoid as a drive unit separate from the feed motor 520.

[0086] In the first and second embodiments, the manual feed unit 235 moves the pickup roller 502 to the contact position when a job start command for feeding a required number of sheets S from a sheet stack supported on the feed tray 6 is issued from the CPU 101, but is not limited to this. The manual feed unit 235 may be configured to move the pickup roller 502 to the contact position when the sheet presence / absence detection sensor 17, which detects whether or not the sheets S are placed on the feed tray 6, detects the placement of the sheets.

[0087] In this configuration, it is preferable that manual feed unit 235 is configured to move pickup roller 502 from the contact position to the separated position when a job is not started and a feeding operation is not performed before a predetermined time has elapsed. This allows manual feed unit 235 to prevent pickup roller 502 from continuing to contact a sheet placed on feed tray 6 and leaving a mark on the sheet by pickup roller 502 when a sheet is placed on feed tray 6 and a feeding operation is not performed.

[0088] Also, in the first and second embodiments, the control unit 100 has been described as being provided in the image forming apparatus 201. However, this is not limiting, and for example, the control unit may be provided in a feeding deck connected to the image forming apparatus 201. In other words, the control unit may be disposed in any device as long as it is electrically connected to the sheet feeding unit and the air blowing unit and the control unit is capable of controlling them.

[0089] The present disclosure can also be realized by a process in which a program for implementing one or more 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. It can also be realized by a circuit (e.g., ASIC) that implements one or more functions. [Explanation of symbols]

[0090] 6...Feed tray (sheet support section, manual feed tray) / 14a, 14b...Side edge regulating plate (regulating section) / 100...Control section / 140a, 140b...Abutment surface / 150a, 150b...Air blowing section (air handling section) / 201...Image forming device / 201B...Image forming section / 210...Laser scanner (exposure means) / 212...Photosensitive drum (image carrier) / 235...Manual feed section (sheet feed device) / 500...First sheet feed section (sheet feed section) / 502...Pickup roller (feed rotating body) / 506...Pulling roller (second sheet feed section) / 520...Feed motor (drive section, motor, first motor) / 520a...Drive mechanism / 521...Transport motor (second motor) / S...Sheet

Claims

1. A seat support section that supports the seat, A sheet feeding unit comprising a feeding rotating body that is movable between a contact position in contact with the sheet supported by the sheet support and a separation position away from the sheet supported by the sheet support, and a drive unit that drives the feeding rotating body, wherein the drive unit drives the sheet feeding unit to feed the sheet supported by the sheet support, An air blowing unit that performs a blowing operation to blow air onto the side surface of the sheet supported by the aforementioned sheet support unit, The system includes a control unit that controls the movement of the feeding rotating body between the contact position and the separated position, the feeding operation by the sheet feeding unit, and the blowing operation by the air handling unit. When a sheet feeding job is started, the control unit moves the feeding rotating body from the separated position to the contact position, and while the feeding rotating body is in the contact position, the air blowing unit performs the blowing operation, and then, with the blowing operation stopped, drives the drive unit to feed multiple sheets using the sheet feeding unit. A sheet feeding device characterized by the following features.

2. The control unit positions the feeding rotating body at the separated position when the job is not being executed. The sheet feeding device according to feature 1.

3. The drive unit is a motor that, by driving and rotating, drives the rotation of the feeding and feeding rotating body and moves the feeding and feeding rotating body between the contact position and the separated position. The sheet feeding device according to feature 2.

4. The motor is driven to rotate in a first direction and a second direction opposite to the first direction. The sheet feeding unit has a drive mechanism that rotates the feeding rotating body when the motor is driven to rotate in the first direction, and moves the feeding rotating body between the contact position and the separated position when the motor is driven to rotate in the second direction. The sheet feeding device according to feature 3.

5. A sheet support portion that supports the sheet, A first sheet feeding unit comprises a feeding rotating body that is movable between a contact position in contact with the sheet supported by the sheet support and a separation position away from the sheet supported by the sheet support, and a drive unit that drives the feeding rotating body, and performs a feeding operation to feed the sheet supported by the sheet support by driving the drive unit, A second sheet feeding unit is provided downstream of the first sheet feeding unit in the sheet transport direction, An air blowing unit that performs a blowing operation to blow air onto the side surface of the sheet supported by the aforementioned sheet support unit, The system includes a control unit that controls the movement of the feeding rotating body between the contact position and the separated position, the feeding operation by the first and second sheet feeding units, and the blowing operation by the air handling unit. The control unit, During the execution of a sheet feeding job, when the first sheet feeding unit starts feeding the sheet, the feeding rotating body is moved to the contact position, and when the sheet fed by the first sheet feeding unit reaches the second sheet feeding unit, the feeding rotating body is moved to the separated position. A sheet feeding device characterized by the following features.

6. The drive unit is a first motor that rotates in a first direction and a second direction opposite to the first direction. The first sheet feeding unit has a drive mechanism that rotates the feeding rotating body when the first motor is rotated in a first direction, and moves the feeding rotating body between the contact position and the separation position when the first motor is rotated in a second direction. The second sheet feeding unit has a second motor that feeds the sheet by rotational drive, The sheet feeding device according to feature 5.

7. The sheet support portion is equipped with a detection means for detecting the sheet supported by the sheet support portion, Based on the detection means detecting the sheet supported by the sheet support portion, the control unit moves the feeding rotating body to the contact position. The sheet feeding device according to feature 1.

8. The control unit moves the feeding rotating body from the contact position to the separated position if the job is not started within a predetermined time after the feeding rotating body has been moved to the contact position. The sheet feeding device according to feature 7.

9. The aforementioned sheet support section is a manual feed tray into which sheets can be inserted by hand. The manual feed tray includes a restricting section that restricts the position of the sheet supported by the tray in the width direction perpendicular to the transport direction, The regulating section has an outlet on the contact surface that contacts the sheet from which air blown out from the air handling section. The sheet feeding device according to feature 1.

10. A sheet feeding device according to claim 1, The system includes an image forming unit that forms an image on a sheet fed from the aforementioned sheet feeding device. An image forming apparatus characterized by the following features.

11. The image forming unit comprises an image carrier that carries and rotates a toner image, and an exposure means for exposing the image carrier. When the control unit executes the job, it performs the blowing operation using the air handling unit before exposing the image carrier to the exposure means. The image forming apparatus according to feature 10.

Images