Patent Application
20240425311
The present invention relates to a sheet feeding apparatus that performs a blowing operation for separating sheets from each other by blowing air on the sheets, and to an image forming apparatus.
An image forming apparatus, such as a copying machine, a facsimile, or a printer, includes a sheet feeding apparatus, such as a feeding cassette or a feeding deck, that sets a bundle of sheets to be supplied to an image forming portion that forms images. In recent years, it has been desired to form images on a variety of types of sheets, and there is a case in which sheets, such as coated paper sheets, that have a smooth surface property are used as a recording material. However, if a bundle of such sheets having smooth surfaces is set in a sheet feeding apparatus, the feeding of the sheets may become difficult because the close contact force between the sheets has a higher value. As countermeasures, Japanese Patent Application Publication No. 2006-256819 proposes a configuration in which sheets are lifted and floated by blowing air on the sheet bundle for separating the sheets from each other.
In the configuration of the image forming apparatus as described in Japanese Patent Application Publication No. 2006-256819 and having the mechanism for blowing air on the sheet bundle, the sheets are generally fed from the sheet feeding apparatus during the air blowing operation. However, if the sheets are fed while the air is blown on the sheets, an edge portion of each sheet bends easily because the sheets are floated. Thus, even if the position of the sheets in the sheet width direction is regulated by regulation plates or the like, an edge portion of each sheet bends if the force that pivots the sheet is applied to the sheet, so that the sheet skews easily.
According to one aspect of the present invention, a sheet feeding apparatus includes a sheet supporting portion configured to support sheets, a sheet feeding portion including a rotary feeding member and a driving portion configured to drive the rotary feeding member and configured to perform a feeding operation that feeds the sheets supported by the sheet supporting portion, by driving the driving portion, the rotary feeding member being configured to move between an abutment position and a separation position, the abutment position being a position at which the rotary feeding member abuts against the sheets supported by the sheet supporting portion, the separation position being a position at which the rotary feeding member is separated from the sheets supported by the sheet supporting portion, an air separating portion configured to perform a blowing operation that blows air on a side surface of the sheets supported by the sheet supporting portion, and a control portion configured to control movement of the rotary feeding member between the abutment position and the separation position, the feeding operation by the sheet feeding portion, and the blowing operation by the air separating portion. In a case where a job for feeding sheets is started, the control portion is configured to move the rotary feeding member from the separation position to the abutment position, causes the air separating portion to perform the blowing operation in a state where the rotary feeding member is positioned at the abutment position, and after the blowing operation, causes the sheet feeding portion to feed a plurality of sheets in a state where the control portion stops the blowing operation, by driving the driving portion.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Hereinafter, a first embodiment of the present invention will be described in detail with reference to the accompanying drawings. First, an image forming apparatus 201 of the present embodiment will be described with reference to
As illustrated in
The image forming portion 201B that serves as an image forming portion has a four-drum full-color system. The image forming portion 201B includes a laser scanner 210 that serves as an exposure portion, and four process cartridges 211Y, 211M, 211C, and 211K which form four-color toner images of yellow (Y), magenta (M), cyan (C), and black (K). Each of the process cartridges 211 includes a photosensitive drum 212 that serves as an image bearing member, a charger 213 that serves as a charging portion, and a development unit 214 that serves as a developing portion. In addition, the image forming portion 201B includes an intermediate transfer unit 201C and a fixing portion 201E, which are disposed above the process cartridges 211. Note that toner cartridges 215 supply toner to the development units 214.
The intermediate transfer unit 201C includes an intermediate transfer belt 216 wound around a driving roller 216a and a tension roller 216b. Note that inside the intermediate transfer belt 216, primary transfer rollers 219 are each disposed in contact with the intermediate transfer belt 216 at a position facing a corresponding photosensitive drum 212. The intermediate transfer belt 216 is rotated by the driving roller 216a, which is driven by a driving portion (not illustrated), in a direction indicated by an arrow.
In addition, toner images formed on the photosensitive drums and having respective colors and negative polarity are multiple-transferred sequentially onto the intermediate transfer belt 216 by the primary transfer rollers 219. At a position facing the driving roller 216a of the intermediate transfer unit 201C, a secondary transfer roller 217 is disposed for transferring a color image formed on the intermediate transfer belt 216, onto the sheet S. A secondary transfer portion 201D is formed between the intermediate transfer belt 216 and the secondary transfer roller 217. In addition, the fixing portion 201E is disposed above the secondary transfer roller 217, and includes a pressing roller 220a and a heating roller 220b. In the upper left with respect to the fixing portion 201E, a first discharging roller pair 225a, a second discharging roller pair 225b, and a both-sides reversing portion 201F are disposed. The both-sides reversing portion 201F includes a reversing roller pair 222 that can rotate in a forward or reverse direction, and a re-conveyance path R. The re-conveyance path R is used to re-convey a sheet having an image formed on one side of the sheet, to the image forming portion 201B.
In a lower portion of the image forming apparatus body 201A, a sheet feeding unit 230 is disposed for feeding sheets S, which are set in the sheet feeding unit 230, to the image forming portion 201B. The sheet feeding unit 230 includes a feeding cassette 1 that stores sheets, and a sheet feeding portion 5 that feeds the sheets S stored in the feeding cassette 1. The sheet feeding portion 5 includes a pickup roller 2, a feed roller 3, and a retard roller 4. The feed roller 3 and the retard roller 4 serve as a separation portion that separates a multi-fed sheet S, sent from the pickup roller 2, from the other.
In addition, in a side face of the image forming apparatus body 201A on the right side in
Next, an image forming operation of the image forming apparatus 201 will be described. First, the image forming apparatus 201 obtains the image information of a document. The image information of the document is obtained by the image reading apparatus 202 reading the image information. In another case, the image information of the document is obtained by receiving print image data outputted from a host apparatus 900 (see
The image information obtained by the image forming apparatus 201 is subjected to image processing, then converted to an electrical signal, and then transmitted to the laser scanner 210 of the image forming portion 201B. In the image forming portion 201B, the surface of the photosensitive drum 212, uniformly charged by the charger 213 so as to have a predetermined polarity and electric potential, is sequentially exposed by a laser beam. With this operation, electrostatic latent images of yellow, magenta, cyan, and black are sequentially formed on the photosensitive drums of the process cartridges 211.
After that, the electrostatic latent images are visualized by developing the electrostatic latent images by using toners of respective colors, and the toner images having respective colors and formed on the photosensitive drums are transferred onto the intermediate transfer belt 216 by a primary transfer bias applied to the primary transfer rollers 219 such that one toner image is superposed on another. With this operation, the toner images are formed on the intermediate transfer belt 216.
On the other hand, the sheet S fed by the feed roller 3 of the sheet feeding unit 230 is conveyed to a registration roller pair 240 (which is hereinafter referred to as a registration roller pair) constituted by a driving roller and a driven roller. When the sheet S is conveyed to the registration roller pair 240, the registration roller pair 240 is in a stop state, and the leading edge of the sheet S is abutted against the registration roller pair 240 that is in the stop state. With this operation, the leading edge of the sheet S is aligned with the registration roller pair 240. After that, since the conveyance of the sheet S is continued by the feed roller 3, a bending (loop) is formed in the sheet S. When the amount of loop of the sheet S reaches a predetermined amount, the registration roller pair 240 is driven. With this operation, the skew of the sheet S is corrected by the registration roller pair 240, and the sheet S whose skew has been corrected is conveyed to the secondary transfer portion 201D by the registration roller pair 240. In the secondary transfer portion 201D, the toner images are collectively transferred onto the sheet S by a secondary transfer bias applied to the secondary transfer roller 217. The sheet S onto which the toner images have been transferred is conveyed to the fixing portion 201E. In the fixing portion 201E, the sheet S is heated and pressed, so that the toners having respective colors are melted and mixed with each other and the toner images are fixed to the sheet S as a color image.
After that, the sheet S, to which the images are fixed, is discharged to the discharging space V by the first discharging roller pair 225a and the second discharging roller pair 225b disposed downstream of the fixing portion 201E, and is stacked on a stacking portion 223 formed in the bottom surface of the discharging space V. In a case where images are formed on both sides of the sheet S, after an image is fixed to the sheet S, the sheet S is conveyed to the re-conveyance path R by the reversing roller pair 222, and conveyed to the image forming portion 201B again.
Next, a configuration of a control system of the image forming apparatus 201 will be described with reference to
For example, the control portion 100 of the first embodiment is included in the image forming apparatus 201, and includes a CPU 101, a ROM 102, and a RAM 103. The control portion 100 is a control portion that controls the image forming apparatus 201. The control portion 100 is connected to the host apparatus 900 and the operation portion 730, and sends/receives information to/from the host apparatus 900 and the operation portion 730. In addition, the control portion 100 processes signals to be sent to various types of process apparatuses, and performs sequence control. Note that the host apparatus 900 is an external apparatus, such as a personal computer, an image scanner, or a facsimile.
The control portion 100 is connected to below-described fan motors 15a and 15b, a sheet detection sensor 17, and a sheet feeding motor 520. The sheet feeding motor 520 serves as a driving portion, a motor, or a first motor that drives the pickup roller 502 and the feed roller 503. In addition, the control portion 100 is connected to a conveyance motor 521 that serves as a second motor that drives a drawing roller 506.
The sheet feeding motor 520 rotates the pickup roller 502 and the feed roller 503 by rotating in a CW direction (i.e., a first direction). In addition, the sheet feeding motor 520 moves the pickup roller 502 between two positions: an abutment position and a separation position, by rotating in a CCW direction (i.e., a second direction) opposite to the CW direction. The abutment position is a position at which the pickup roller 502 is abutted against the sheet S, and the separation position is a position at which the pickup roller 502 is not abutted against the sheet S.
The sheet feeding motor 520 is linked to the pickup roller 502 and the feed roller 503, via a driving mechanism 520a. The driving mechanism 520a includes a driving gear that transmits the driving force to the pickup roller 502 and the feed roller 503. The driving force causes the pickup roller 502 and the feed roller 503 to rotate in a direction in which the sheet is fed. In addition, the driving mechanism 520a includes a moving mechanism that moves (lifts and lowers) the pickup roller 502 between the two positions: the abutment position and the separation position. In addition, the driving mechanism 520a includes one-way clutches. When the sheet feeding motor 520 rotates in the CW direction (i.e., a forward direction), the one-way clutch transmits the driving force to the driving gear, and does not transmit the power to the moving mechanism. When the sheet feeding motor 520 rotates in the CCW direction (i.e., a reverse direction), the one-way clutch transmits the driving force to the moving mechanism, and does not transmit the power to the driving gear.
In the manual feeding portion 235, if the sheet feeding motor 520 is rotated in the CW direction (i.e., a forward direction), the driving force is transmitted to the pickup roller 502 and the feed roller 503. The driving force causes the pickup roller 502 and the feed roller 503 to rotate in a direction in which the sheet is fed. In addition, in the manual feeding portion 235, if the sheet feeding motor 520 is rotated in the CCW direction (i.e., a reverse direction), the pickup roller 502 is moved between the two positions: the abutment position and the separation position.
The CPU 101 of the control portion 100 detects the pickup roller 502 located at the abutment position, depending on a signal outputted when the state of a home-position detection sensor, disposed in the moving mechanism, becomes an ON state. In addition, the CPU 101 moves the pickup roller 502 to the separation position by rotating the sheet feeding motor 520 in a reverse direction until a time sufficient to move the pickup roller 502 to the separation position has elapsed since the state of the home-position detection sensor was in the ON state. The detailed description thereof will be made below.
Next, the detailed description of the manual feeding portion 235, which serves as a sheet feeding apparatus, will be made with reference to
As illustrated in
In addition, in the manual feeding portion 235, the drawing roller 506 that serves as a second sheet-feeding portion is disposed at a position positioned downstream of the feed roller 503 and the retard roller 504 in a conveyance direction Y1 of the sheet S.
In addition, the manual feeding portion 235 includes the sheet detection sensor 17 that is disposed in the feeding tray 6, and that detects the sheet S placed on the feeding tray 6. In addition, the manual feeding portion 235 includes a feeding detection sensor 505 that is disposed between the rollers (i.e., the feed roller 503 and the retard roller 504) and the drawing roller 506 in the conveyance direction Y1 of the sheet S, and that detects the passage of the sheet S.
The feeding tray 6 includes side-edge regulation plates, 14a and 14b, that serve as a regulation portion for regulating the position of the sheet S in a direction (i.e., a sheet width direction) orthogonal to the conveyance direction Y1 of the sheet S. The side-edge regulation plates 14a and 14b respectively include air blowing portions 150a and 150b that serve as an air separating portion.
The air blowing portion 150a of the side-edge regulation plate 14a includes a fan 151a that is driven by the fan motor 15a (see
Similarly, the air blowing portion 150b of the side-edge regulation plate 14b includes a fan 151b that is driven by the fan motor 15b (see
In the first embodiment, each of the fan motors 15a and 15b is PWM-controlled, and each of the fans 151a and 151b is a blower fan having a diameter φ of 97 mm. In the manual feeding portion 235, in the air blowing operation, each of the fan motors 15a and 15b is PWM-controlled at a predetermined duty ratio (e.g., 40%), as the PWM duty ratio, for blowing the air.
In the feeding tray 6, the air is blown from the fan motors 15a 15b toward the edge portions of the sheet S as indicated by arrows A1 and A2, so that upper sheets of the sheet bundle are lifted and floated and the close contact force between sheets is reduced.
As described above, the operation for moving the pickup roller 502 to the abutment position, at which the pickup roller 502 is abutted against the sheet S, is performed by using the driving force of the sheet feeding motor 520 (see
Thus, in the manual feeding portion 235, since the air is blown, the close contact force between sheets can be reduced while variations in position of the sheets is kept to a minimum.
If the sheet S is bent by the air blown by the air blowing portions 150a and 150b, the sheet S will pivot and skew when conveyed. However, the pivot and skew of the sheet S can be suppressed by the manual feeding portion 235 in the above-described manner.
First, the CPU 101 lowers the pickup roller 502 to the abutment position, and causes the pickup roller 502 to abut against the sheet S (S1). In this process, the CPU 101 rotates the sheet feeding motor 520 in a reverse direction until the state of the home-position detection sensor, disposed in the moving mechanism of the driving mechanism 520a, becomes an ON state; and thereby lowers the pickup roller 502 from the separation position to the abutment position, at which the pickup roller 502 abuts against the sheet S. By executing Step S1, the state illustrated in
Then the CPU 101 causes the air blowing portions 150a and 150b to blow air (S2). In this process, the CPU 101 causes the air blowing portions 150a and 150b to blow air by driving the fan motors 15a and 15b. Since the air is blown by the air blowing portions 150a and 150b in a state where the pickup roller 502 is positioned at the abutment position, the state illustrated in
Then the CPU 101 determines whether a blowing time has elapsed since the air blowing portions 150a and 150b started to blow the air (S3). In this process, if the CPU 101 determines that the blowing time has not elapsed (No), then the CPU 101 returns to Step S2, and repeats the process of the steps S2 and S3 until the blowing time has elapsed.
The blowing time is set in advance by the CPU 101, so as to have an appropriate value, based on a media property such as the grammage or surface property of the sheet S to be fed, and the environment information, such as room temperature and humidity, on the environment in which the image forming apparatus 201 is operated.
If the CPU 101 determines in the process of Step S3 that the blowing time has elapsed (Yes), then the CPU 101 causes the air blowing portions 150a and 150b to stop blowing the air (S4). Then the CPU 101 executes the feeding operation for the Sheet S by rotating the pickup roller 502 and the feed roller 503 in a direction in which the pickup roller 502 and the feed roller 503 can convey the sheet S in the conveyance direction Y1, by rotating the sheet feeding motor 520 in a forward direction (S5). By executing the feeding operation for the sheet S after the air blowing portions 150a and 150b stop blowing the air, the state illustrated in
In the manual feeding portion 235, after the stop of blowing the air, the state of the sheet S that was floated is returned to the state of the sheet S that is of the bundle (the state is a state before the sheet is lifted and floated) by executing the processes of the steps S4 and S5 (the state of the sheet S that was floated is returned to the state of the sheet S that is of the bundle while the air between sheets is removed from between the sheets). When the state of the sheet S that was floated is returned to the state of the sheet S that is of the bundle, the close contact force between sheets remains to have a smaller value, to which the close contact force was decreased by the air blowing operation. Thus, in the manual feeding portion 235, the pickup roller 502 can be prevented from slipping on a sheet and becoming unable to convey the sheet, for example. That is, even if the sheets have strong close-contact force, the manual feeding portion 235 can feed the sheets. The processes of the steps SI to S5 serve as the feeding process of the first embodiment.
Then the CPU 101 determines whether the feeding of the necessary number of sheets has been completed (S6). In this process, the CPU 101 determines whether the feeding of the necessary number of sheets has been completed, based on the number of sheets whose passage was detected by the feeding detection sensor 505. If the CPU 101 determines in the process of Step S6 that the feeding of the necessary number of sheets has not been completed (No), then the CPU 101 returns to Step S5, and repeats the processes of the steps S5 and S6 until the feeding of the necessary number of sheets is completed.
If the CPU 101 determines in the process of Step S6 that the feeding of the necessary number of sheets S has been completed (Yes), then the CPU 101 determines that the job for feeding the necessary number of sheets has been completed, and that the CPU 101 is in a state where the CPU 101 is not executing the job (non-operation state). Then the CPU 101 lifts the pickup roller 502 from the abutment position, at which the pickup roller 502 is abutted against the sheet S, to the separation position, at which the pickup roller 502 is not abutted against the sheet S, by rotating the sheet feeding motor 520 in a reverse direction (S7). Then the CPU 101 causes the manual feeding portion 235 to end the feeding operation for the sheet S.
Thus, in the manual feeding portion 235 of the first embodiment, the pickup roller 502 is kept at the abutment position while a job is executed. With this operation, the manual feeding portion 235 can feed sheets sequentially from a sheet bundle, until a necessary number of sheets is fed and the job is completed, by keeping the pickup roller 502 at the abutment position and rotating the pickup roller 502.
In addition, since the pickup roller 502 is positioned at the separation position in the non-operation state where the job is not executed, the manual feeding portion 235 can prevent the pickup roller 502 from interfering with sheets when the sheets are placed on the feeding tray 6.
As described above, even if sheets, such as coated paper sheets, have a smooth surface property, the manual feeding portion 235 of the first embodiment can feed the sheets by reducing the close contact force of the sheets, by separating a few to dozens of upper sheets of the sheet bundle from each other by performing the air blowing operation. In addition, when the manual feeding portion 235 performs the air blowing operation, the manual feeding portion 235 causes the pickup roller 502 to abut against the leading edge of the sheets.
If the sheet S is bent by the air blown by the air blowing portions 150a and 150b, the sheet S will pivot and skew when conveyed. However, the pivot and skew of the sheet S can be suppressed by the manual feeding portion 235 in the above-described manner.
In addition, the feeding operation for the sheets is performed after the air blowing operation is stopped. Thus, the amount of skew of sheets fed from the manual feeding portion 235 can be improved, compared with the amount of skew of sheets in a configuration in which the feeding operation is performed while the air blowing operation is performed. Thus, the amount of skew correction required for the registration roller pair 240 to perform can be made smaller. As a result, the variations in position of sheets conveyed to the secondary transfer portion 201D can be deceased, so that the print precision (quality) can be improved.
Next, an image forming apparatus 201 of a second embodiment will be described. The image forming apparatus 201 of the second embodiment can move the pickup roller 502 to the separation position during a job for feeding a necessary number of sheets S from a sheet bundle supported by the feeding tray 6. In this point, the image forming apparatus 201 of the second embodiment differs from the above-described first embodiment. Since the other configuration of the second embodiment is the same as that of the first embodiment, a component identical to that of the first embodiment is given an identical symbol, a control process identical to that of the first embodiment is given an identical step number, and the description thereof will be omitted.
After executing the process of Step S5, the CPU 101 determines whether the CPU 101 has fed the leading edge of the sheet S to a first position (S11). In the second embodiment, the first position is a position separated from the drawing roller 506, which is positioned downstream of the feed roller 503 in the conveyance direction of the sheet S, by a first distance (e.g., 10 mm) in the conveyance direction of the sheet S and positioned downstream of the drawing roller 506. The CPU 101 determines whether the leading edge of the sheet S has reached the first position, by performing computation by using the speed at which the sheet S is fed and the time which has elapsed since the feeding detection sensor 505, positioned between the feed roller 503 and the drawing roller 506, detected the leading edge of the sheet S.
If the CPU 101 determines in the process of Step S11 that the CPU 101 has not fed the leading edge of the sheet S to the first position (No), then the CPU 101 returns to Step S5. On the other hand, if the CPU 101 determines in the process of Step S11 that the CPU 101 has fed the leading edge of the sheet S to the first position (Yes), then the CPU 101 proceeds to Step S12.
In the process of Step S12, the CPU 101 lifts the pickup roller 502 from the abutment position, at which the pickup roller 502 is abutted against the sheet S, to the separation position, at which the pickup roller 502 is not abutted against the sheet S, by rotating the sheet feeding motor 520 in a reverse direction (S12). As described above, in the manual feeding portion 235, if the sheet feeding motor 520 is rotated in the reverse direction, the pickup roller 502 is moved between the abutment position and the separation position, via a drive train portion. In addition, if the sheet feeding motor 520 is rotated in a forward direction, the pickup roller 502 and the feed roller 503 are rotated in a direction in which the pickup roller 502 and the feed roller 503 can convey the sheet S in the conveyance direction Y1.
Thus, in the manual feeding portion 235, the process of Step S12 is executed and the sheet feeding motor 520 is rotated in the reverse direction, so that the pickup roller 502 is moved to the separation position and separated from the sheet S. In addition, in the manual feeding portion 235, when the sheet feeding motor 520 is rotated in the reverse direction, the feed roller 503 is also not rotated in the direction in which the feed roller 503 can convey the sheet S in the conveyance direction Y1.
In the manual feeding portion 235, however, the sheet S has already reached the drawing roller 506, and the drawing roller 506 is being rotated by the conveyance motor 521 that is different from the sheet feeding motor 520. Thus, in the manual feeding portion 235, even in a case where the process of Step S12 is executed and the sheet feeding motor 520 is being rotated in the reverse direction, the conveyance of the sheet S can be continued by the drawing roller 506.
Then the CPU 101 determines whether the CPU 101 has fed the trailing edge of the sheet S to a second position (S13). In the second embodiment, the second position is a position separated from the feed roller 503 by a second distance (e.g., 10 mm) in the conveyance direction of the sheet S and positioned downstream of the feed roller 503. The CPU 101 determines whether the trailing edge of the sheet S has reached the second position, based on the time which has elapsed since the feeding of the sheet S was started, and the length of the sheet S in the conveyance direction Y1.
If the CPU 101 determines in the process of Step S13 that the CPU 101 has not fed the trailing edge of the sheet S to the second position (No), then the CPU 101 repeats the process of Step S13, while continuing the feeding operation, until the trailing edge of the sheet S reaches the second position. On the other hand, if the CPU 101 determines in the process of Step S13 that the CPU 101 has fed the trailing edge of the sheet S to the second position (Yes), then the CPU 101 proceeds to Step S14.
In the process of Step S14, the CPU 101 determines whether the feeding of the necessary number of sheets has been completed (S14). In this process, the CPU 101 determines whether the feeding of the necessary number of sheets has been completed, based on the number of sheets whose passage was detected by the feeding detection sensor 505.
If the CPU 101 determines in the process of Step S14 that the CPU 101 has completed the feeding of the necessary number of sheets S (Yes), then the CPU 101 determines that the job for feeding the necessary number of sheets has been completed, and causes the manual feeding portion 235 to end the feeding operation of the sheet S. In the manual feeding portion 235, at a point of time at which the job is completed, the pickup roller 502 is in a state where the pickup roller 502 is positioned at the separation position by executing the process of Step S12. In other words, in the manual feeding portion 235 of the second embodiment, in a state (i.e., a non-operation state) where the job is not being executed, the pickup roller 502 is positioned at the separation position.
On the other hand, if the CPU 101 determines in the process of Step S14 that the CPU 101 has not completed the feeding of the necessary number of sheets (No), then the CPU 101 lowers the pickup roller 502 to the abutment position, and causes the pickup roller 502 to abut against the uppermost sheet of the sheet bundle (S15). Then the CPU 101 returns to Step S5.
Since the CPU 101 returns to Step S5 after executing the process of Step S15, the processes of the steps S5 to S15 are repeated in the manual feeding portion 235 until the necessary number (which is set in the job) of sheets S are fed. That is, the manual feeding portion 235 moves the pickup roller 502 from the abutment position to the separation position every time the drawing roller 506 is allowed to feed a sheet, until a necessary number of sheets S is fed from a sheet bundle supported by the feeding tray 6. In addition, the manual feeding portion 235 moves the pickup roller 502 positioned at the separation position, to the abutment position before the feeding of a new sheet from the sheet bundle is started.
If the pickup roller 502 is continuously in contact with the sheet bundle (supported by the feeding tray 6) until the necessary number (which is specified in the job) of sheets is fed, a mark of the pickup roller 502 will be left on sheets. In the present embodiment, however, the manual feeding portion 235 can suppress the mark from being left on the sheets.
As illustrated in
In the manual feeding portion 235, at a time t2 at which a time T6 has elapsed since the time t1 at which the pickup roller 502 abutted against the abutment position, the air blowing operation by the air blowing portions 150a and 150b is started by driving the fan motors 15a and 15b. In the manual feeding portion 235, in the air blowing operation, each of the fan motors 15a and 15b is PWM-controlled at a predetermined ratio (e.g., 40%), as the PWM duty ratio, for blowing the air. The air blowing operation is performed until a time T11 (e.g., 10 seconds), as a blowing time, elapses.
In the manual feeding portion 235, the air blowing operation by the air blowing portions 150a and 150b is started at the time t2, and is ended at a time t3 at which the time T11 has elapsed since the time t2. In the manual feeding portion 235, at a time t5 at which a time T12 has elapsed since the time t3 at which the air blowing operation was ended, the feeding of the uppermost sheet S of the sheet bundle supported by the feeding tray 6 is started. In the manual feeding portion 235, at the time t5, the rotation of the sheet feeding motor 520 in a forward direction is started by a voltage V1, and the conveyance motor 521 is also rotated by the voltage V1. With this operation, in the manual feeding portion 235, the feeding of the uppermost sheet S of the sheet bundle supported by the feeding tray 6 is started by the pickup roller 502 of the first sheet-feeding portion 500.
In the image forming apparatus 201, at a time t4 in a period of time from the time t3 at which the air blowing operation is ended, to the time t5 at which the feeding operation by the first sheet-feeding portion 500 is started, the exposure of the surface of the photosensitive drum 212 by the laser scanner 210 is started. In other words, the image forming apparatus 201 causes the air blowing portions 150a and 150b to perform the air blowing operation before the image forming portion 201B starts the image formation by using the image information obtained by the image forming portion 201B by performing the exposure of the surface of the photosensitive drum 212 by the laser scanner 210.
The air blowing operation by the air blowing portions 150a and 150b causes the feeding tray 6 to vibrate, which causes the failure in image formation performed by the image forming portion 201B. In the above-described configuration, however, the manual feeding portion 235 of the second embodiment can prevent the failure in image formation, which is caused by the vibration of the feeding tray 6.
In the manual feeding portion 235, at a time t7 at which a time T13 has elapsed since a time t6 at which the feeding detection sensor 505 detected the leading edge of the sheet S, the leading edge of the sheet S reaches the first position positioned downstream of the drawing roller 506 in the conveyance direction. In the manual feeding portion 235, the rotation of the sheet feeding motor 520 in the forward direction, made by the voltage V1, is stopped; and at a time t8 at which a time T14 has elapsed since the time t7, the rotation of the sheet feeding motor 520 in the reverse direction is started by the voltage V2, and the movement of the pickup roller 502 from the abutment position toward the separation position is started. In the manual feeding portion 235, at a time t9 at which a time T15 has elapsed since the time t8, the CPU 101 determines, based on the elapsed time, that the pickup roller 502 has reached the separation position, and stops the rotation of the sheet feeding motor 520 in the reverse direction.
In the manual feeding portion 235, in the period of time from the time t7 to the time t9, the rotation of the conveyance motor 521 by the voltage VI is continued. Thus, in the manual feeding portion 235, even after the time t7 at which the rotation of the sheet feeding motor 520 in the forward direction is stopped, the feeding of the sheet S is continued by the drawing roller 506 rotated by the conveyance motor 521.
As described above, even if sheets, such as coated paper sheets, have a smooth surface property, the manual feeding portion 235 of the second embodiment can feed the sheets by reducing the close contact force of the sheets, by separating a few to dozens of upper sheets of the sheet bundle from each other by performing the air blowing operation. In addition, when the manual feeding portion 235 performs the air blowing operation, the manual feeding portion 235 causes the pickup roller 502 to abut against the leading edge of the sheets.
If the sheet S is bent by the air blown by the air blowing portions 150a and 150b, the sheet S will pivot and skew when conveyed. However, the pivot and skew of the sheet S can be suppressed by the manual feeding portion 235 in the above-described manner.
In addition, the feeding operation for the sheets is performed after the air blowing operation is stopped. Thus, the amount of skew of sheets fed from the manual feeding portion 235 can be improved, compared with the amount of skew of sheets in a configuration in which the feeding operation is performed while the air blowing operation is performed. Thus, the amount of skew correction required for the registration roller pair 240 to perform can be made smaller. As a result, the variations in position of sheets conveyed to the secondary transfer portion 201D can be deceased, so that the print precision (quality) can be improved.
In addition, when the fed sheet S reaches the drawing roller 506 positioned downstream of the first sheet-feeding portion 500 in the conveyance direction, the manual feeding portion 235 of the second embodiment moves the pickup roller 502 from the abutment position to the separation position. If the pickup roller 502 is continuously in contact with the sheet bundle (supported by the feeding tray 6) until the necessary number (which is specified in the job) of sheets are fed, a mark of the pickup roller 502 will be left on sheets. In the present embodiment, however, the manual feeding portion 235 can suppress the mark from being left on the sheets.
In the above-described first and second embodiments, the description has been made for the sheet feeding control performed by the manual feeding portion 235 that includes the air blowing portions 150a and 150b. However, the present disclosure is not limited to this. For example, the sheet feeding control in the first and the second embodiments may be performed by the sheet feeding unit 230 that includes the feeding cassette 1, or by a feeding deck that can be connected to the image forming apparatus 201 and that includes an air blowing portion. In a case where the sheet feeding control in the first and the second embodiments is performed by the sheet feeding unit 230, any one of the sheet feeding units 230 in the up-down direction may perform the sheet feeding control. That is, the sheet supporting portion that supports the sheet bundle may have any configuration.
In the first and the second embodiments, the first sheet-feeding portion 500 lifts and lowers the pickup roller 502 by rotating the sheet feeding motor 520, which rotates the pickup roller 502 and the feed roller 503, in a reverse direction. However, the present disclosure is not limited to this. For example, the first sheet-feeding portion 500 may move the pickup roller 502 between the abutment position and the separation position by using a different actuator, such as a motor or a solenoid, that is a driving portion different from the sheet feeding motor 520.
The manual feeding portion 235 of the first and the second embodiments moves the pickup roller 502 to the abutment position if a start command of a job is issued from the CPU 101 for feeding a necessary number of sheets from a sheet bundle supported by the feeding tray 6. However, the present disclosure is not limited to this. For example, the manual feeding portion 235 may move the pickup roller 502 to the abutment position when the sheet detection sensor 17 for detecting a sheet S placed on the feeding tray 6 detects the sheet S.
In this case, it is preferable that the manual feeding portion 235 move the pickup roller 502 from the abutment position to the separation position if the job was not started and the feeding operation was not executed by the time when a predetermined time has elapsed. With this operation, in a case where sheets are placed on the feeding tray 6 and the feeding operation is not executed, the manual feeding portion 235 can suppress the pickup roller 502 from being continuously in contact with the sheets, and the mark of the pickup roller 502 from being left on the sheets.
In the first and the second embodiments, the description has been made for the case where the control portion 100 is included in the image forming apparatus 201. However, the present disclosure is not limited to this. For example, the control portion 100 may be included in a feeding deck connected to the image forming apparatus 201. That is, the control portion 100 may be disposed in any apparatus as long as the control portion that can control the sheet feeding portion and the air blowing portion is electrically connected to the sheet feeding portion and the air blowing portion.
Embodiment(s) of the present invention can also be realized by a computer of a system or apparatus that reads out and executes computer executable instructions (e.g., one or more programs) recorded on a storage medium (which may also be referred to more fully as a ‘non-transitory computer-readable storage medium’) to perform the functions of one or more of the above-described embodiment(s) and/or that includes one or more circuits (e.g., application specific integrated circuit (ASIC)) for performing the functions of one or more of the above-described embodiment(s), and by a method performed by the computer of the system or apparatus by, for example, reading out and executing the computer executable instructions from the storage medium to perform the functions of one or more of the above-described embodiment(s) and/or controlling the one or more circuits to perform the functions of one or more of the above-described embodiment(s). The computer may comprise one or more processors (e.g., central processing unit (CPU), micro processing unit (MPU)) and may include a network of separate computers or separate processors to read out and execute the computer executable instructions. The computer executable instructions may be provided to the computer, for example, from a network or the storage medium. The storage medium may include, for example, one or more of a hard disk, a random-access memory (RAM), a read only memory (ROM), a storage of distributed computing systems, an optical disk (such as a compact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™), a flash memory device, a memory card, and the like.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2023-103757, filed Jun. 23, 2023, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2023-103757 | Jun 2023 | JP | national |
