Patent Grant
10384893
The present invention relates to a sheet conveying apparatus configured to convey a sheet, and to an image reading apparatus and an image forming apparatus which include such a sheet conveying apparatus.
As a sheet conveying apparatus, there has been proposed, as disclosed in Japanese Patent Application Laid-Open No. H05-201587, an apparatus which corrects skew feed of a sheet by setting a conveyance speed difference to a pair of conveyance rollers arranged apart from each other by a predetermined interval in a width direction of a sheet orthogonal to a conveyance direction of a sheet.
However, when the conveyance speed difference is set to the pair of conveyance rollers as disclosed in Japanese Patent Application Laid-Open No. H05-201587, there is a fear in that wrinkles are formed in a sheet between the pair of conveyance rollers and a roller arranged upstream of the pair of conveyance rollers.
The present invention provides a sheet conveying apparatus which is less liable to cause formation of wrinkles in a sheet during sheet conveyance.
According to one embodiment of the present invention, a sheet conveying apparatus, comprises:
a separation-conveyance portion configured to separate and convey a sheet;
a first conveyance rotary member, which is provided downstream of the separation-conveyance portion in a sheet conveyance direction and is configured to further convey the sheet at a predetermined conveyance speed in contact with the sheet being conveyed by the separation-conveyance portion;
a second conveyance rotary member, which is provided downstream of the separation-conveyance portion in the sheet conveyance direction, is arranged apart from the first conveyance rotary member by a predetermined interval in a width direction orthogonal to the sheet conveyance direction, and is configured to convey the sheet being conveyed by the separation-conveyance portion in cooperation with the first conveyance rotary member; and
a third conveyance rotary member, which is arranged at a position between a position at a most downstream end of the separation-conveyance portion and a position at a most downstream end of the first conveyance rotary member or the second conveyance rotary member in the sheet conveyance direction and is configured to convey the sheet being conveyed by the separation-conveyance portion,
wherein a conveyance speed of the sheet by the second conveyance rotary member is changeable to a first conveyance speed which is the same as a conveyance speed of the sheet by the first conveyance rotary member and a second conveyance speed which is different from the first conveyance speed, and
wherein, when the conveyance speed of the sheet by the first conveyance rotary member is set to the first conveyance speed and the conveyance speed of the sheet by the second conveyance rotary member is set to the second conveyance speed, a conveyance speed of the sheet by the third conveyance rotary member is set to a third conveyance speed which is a speed between the first conveyance speed and the second conveyance speed.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Now, with reference to the attached drawings, embodiments of the present invention will be described in detail.
A first embodiment of the present invention will be described with reference to
(Image Reading Apparatus)
As illustrated in
The original conveying apparatus 120 is turnable with respect to the image reading unit 110 by an opening and closing support mechanism (not shown) using a hinge (not shown), and is capable of opening and closing an upper side of the image reading unit 110. On the upper side of the image reading unit 110, there are arranged an original glass plate 10 and a flow reading glass plate 20. In the image reading unit 110, there is arranged a read-scanning unit 50.
The read-scanning unit 50 radiates light to a lower surface of the original D from a light source (not shown) arranged in a main scanning direction and allows reflected light to be projected on an image pickup element (not shown), to thereby read an image. The read-scanning unit 50 is fixed to a drive belt 54, and a drive force of a drive motor 53 is transmitted through the drive belt 54 so that the read-scanning unit 50 moves along a guide shaft 56 in an arrow C direction. For example, a stepping motor or a DC motor is used as the drive motor 53. A moving direction (arrow C direction) of the read-scanning unit 50 is referred to as a sub-scanning direction, and a direction orthogonal to the sub-scanning direction is referred to as a main scanning direction.
As modes of reading an original, the image reading apparatus 100 is capable of performing reading in a fixed-reading mode and a flow-reading mode, which are to be selected by a user. In the fixed-reading mode, the image reading unit 110 reads an original D1 placed on the original glass plate 10. A user opens the original conveying apparatus 120, places the original D1 on the original glass plate 10, closes the original conveying apparatus 120, and operates a control panel (135 in
In the flow-reading mode, the image reading unit 110 reads the original D conveyed by the original conveying apparatus 120 to the flow reading glass plate 20. A user places the original D on the original placement unit 30 and operates the control panel (135 in
(Original Conveying Apparatus)
As illustrated in
The separation portion E includes a conveyance roller (conveyance member) 32, which rotates so as to convey the original in an original conveyance direction (sheet conveyance direction) G, and a retard roller (separation member) 33, which forms a separation nip with the conveyance roller 32, thereby being capable of separating and conveying a sheet. The retard roller 33 is driven in a direction of conveying the original in a direction opposite to the original conveyance direction G of the conveyance roller 32, and is capable of being driven by the conveyance roller 32. At such separation portion E, while the conveyance roller 32 conveys an uppermost original D to a skew feed correction portion F provided downstream of the separation portion E in the original conveyance direction G, the retard roller 33 pushes back a multi-fed original, which is fed together with the original D, to the original placement unit 30. Further, when one original is conveyed to the separation portion E, the retard roller 33 is driven by the conveyance roller 32 to rotate, thereby conveying the original D to the skew feed correction portion F.
The skew feed correction portion F corrects skew feed of the original D conveyed from the separation portion E, feeds the original D to a conveyance path PS1, and gives the original D to a read roller 36. The read roller 36 is arranged upstream of a platen roller 35. The read roller 36 conveys the original D having been subjected to the skew feed correction by the skew feed correction portion F to the flow reading glass plate 20, and gives the original D to the read roller 37. A read sensor S2 detects a reading start timing for the original D. The read-scanning unit 50 reads an image of the original D at the reading timing detected by the read sensor S2.
The platen roller 35 regulates a rise-up amount of the original D from the upper surface of the flow reading glass plate 20 to retain the lower surface of the original D at a focal point position of the read-scanning unit 50. An image of the original D is read by the read-scanning unit 50 while the original D is conveyed under a state in which the rise-up amount of the original D from the upper surface of the flow reading glass plate 20 is regulated by the platen roller 35 rotating at a predetermined rotation speed.
The read rollers 36 and 37 rotate at a predetermined rotation speed to allow the original D to pass above the flow reading glass plate 20 and move at a constant speed. The read roller 37 is arranged downstream of the platen roller 35, and gives the original D, which has passed above the upper surface of the flow reading glass plate 20, to a delivery roller 38.
When only an image on one side of the original D is to be read, the original D whose image has been read is delivered by the delivery roller 38 to the original delivery portion 39 and stacked thereon. When images on both sides of the original D are to be read, the original D whose image on a first side is read is brought by the delivery roller 38 to a position of protruding toward the original delivery portion 39, and the delivery roller 38 then stops and rotate in a reverse direction so that a leading edge and a trailing edge of the original D is switched to be brought back into the apparatus. At this time, a flapper 40 is switched to a reverse conveyance passage PS2. As a result, the original D having been brought back is fed again to the conveyance path PS1 under a state in which the front and back sides of the original D are reversed as compared to the time of reading the first side. The original D is conveyed above the flow reading glass plate 20 by the read rollers 36 and 37, and an image on a second side of the original D is read by the read-scanning unit 50. After that, the original D is allowed to pass through the reverse conveyance path PS2 and the conveyance path PS1 to set up the page order, and then is delivered by the delivery roller 38 to the original delivery portion 39 and stacked thereon.
(Skew Feed Correction Portion)
As illustrated in
As illustrated in
As illustrated in
The correction roller 34c is capable of conveying the original D in cooperation with the correction roller 34a, and a peripheral speed (hereinafter referred to as “conveyance speed”) of the correction roller 34c can be changed to a conveyance speed which is different from a conveyance speed of the correction roller 34a. With this configuration, in the skew feed correction portion F, different conveyance speeds are set to the correction rollers 34a and 34c based on the skew feed amount of the original D′ determined in accordance with detection results of the skew feed detection sensors S1a and S1b. With this configuration, the original D′ is rotated within a conveyance plane so that, as illustrated with the original D indicated by solid lines, the skew feed of the original D′ is corrected. After the skew feed of the original D′ is corrected, in the skew feed correction portion F, the same conveyance speed is set to the correction rollers 34a and 34c, and the original having been subjected to skew feed correction is conveyed as it is.
(Comparative Example)
Therefore, in the case of the configuration including the skew feed correction portion F′ in the comparative example, there is a fear in that wrinkles are formed in the original D to be conveyed. For example, the separation portion E is arranged upstream of the correction rollers 34a and 34c in the original conveyance direction G, and conveyance resistance such as friction resistance or pull-out resistance by the separation portion E acts on a center portion of the original D in the width direction H. Thus, both sides of the original D are conveyed by the correction rollers 34a and 34c under a state in which the center portion of the original D is pulled by the separation portion E, with the result that warpage as illustrated in
A more specific description will be provided. For example, when a plurality of originals are conveyed in a superposed state (multi-fed), in the separation portion E, while the conveyance roller 32 rotates in a forward direction to feed the uppermost original D to the skew feed correction portion F, the retard roller 33 rotates in a reverse direction to push back the multi-fed original to an upstream side. Then, at the moment at which the multi-fed original is pushed out toward the upstream side, the retard roller 33 having been rotating in the reverse direction applies a significant amount of friction to the lower surface of the uppermost original D to pull the original D toward the upstream side. As a result, the original D is pulled between the correction rollers 34a and 34c arranged apart in the width direction and the separation portion E arranged on the upstream side, and the original D is twisted thereby. Accordingly, as illustrated in
Thus, with the configuration disclosed in Japanese Patent Application Laid-Open No. H05-201587 mentioned above, between the separation portion and the rollers configured to correct the skew feed, a conveyance roller configured to convey a sheet is provided at a position substantially the same as the rollers configured to correct the skew feed in the width direction orthogonal to the original conveyance direction. Therefore, the conveyance passage for conveying the sheet is extended, and downsizing of the apparatus is hindered.
(Skew Feed Correction Portion in First Embodiment)
Therefore, in the first embodiment, as illustrated in
As illustrated in
Thus, the correction roller 34b conveys the original (sheet) D at an intermediate position between the correction roller 34a and the correction roller 34c so as to overcome the conveyance resistance generated in the separation portion E. With this action, the correction roller 34b pulls the original D toward the downstream side while overcoming the conveyance resistance generated in the separation portion E, thereby alleviating the warpage W which occurs between the correction rollers 34a and 34c and the separation portion E.
The correction rollers 34a, 34b, and 34c are arranged so that, as illustrated in
Further, in the first embodiment, the skew feed detection sensors S1a and S1b which are capable of detecting a leading edge of the original D to be conveyed are arranged upstream of the correction rollers 34a, 34b, and 34c in the original conveyance direction G. The skew feed detection sensors S1a and S1b are arranged apart from each other by a predetermined interval in the width direction H so that respective detection positions for detecting the original D are positioned on the same straight line parallel to the width direction H orthogonal to the original conveyance direction G. Therefore, the leading edge of the original D fed by the separation portion E is detected by the skew feed detection sensors S1a and S1b at timings depending on the skew feed amount of the original D. The skew feed detection sensors S1a and S1b are each a reflected light sensor configured to detect reflected light of infrared light emitted from a light source (LED) with a photodiode.
Now, it is assumed that, in order to correct the skew feed of the original D to be conveyed, the correction roller 34a is set to a first conveyance speed, and the correction roller 34c is set to a second conveyance speed different from the first conveyance speed. In this case, the conveyance speed of the correction roller 34b is set to a third conveyance speed between the first conveyance speed and the second conveyance speed. That is, through control by a controller 150, the stepping motor M3 drives the correction roller 34b so that the correction roller 34b conveys the original D at an intermediate conveyance speed between the conveyance speed of the correction roller 34a and the conveyance speed of the correction roller 34c. For example, a rotation speed of the stepping motor M3 is controlled so that the correction roller 34b conveys the original D at a conveyance speed which is an average between the conveyance speed of the correction roller 34a and the conveyance speed of the correction roller 34c.
The stepping motor M3 drives the correction roller 34b without involvement to drive of the correction rollers 34a and 34c. Therefore, any complicated mechanism such as planetary gears is not required, and hence reduction in number of components of the mechanism and downsizing are achieved. In the first embodiment, the correction roller 34b is driven by the stepping motor M3 through intermediation of toothed pulleys 25 and 26 and a toothed belt 27.
As illustrated in
A feed motor M4 drives the pickup roller 31 and the separation portion E. The controller 150 engages the feed clutch 59 to transmit drive of the feed motor M4 to the pickup roller 31, and disengages the feed clutch 59 to cut transmission of the drive of the feed motor M4. The controller 150 controls the stepping motors M1, M2, and M3 to drive the correction rollers 34a, 34b, and 34c. The controller 150 sets conveyance speeds of the correction rollers 34a and 34c based on detection results of the skew feed detection sensors S1a and S1b.
Specifically, the controller 150 calculates a skew feed amount of the original D based on a difference in timings at which the skew feed detection sensors S1a and S1b detect the leading edge of the original D. Based on the calculated skew feed amount, the controller 150 controls the stepping motors M1 and M2 to drive the correction rollers 34a and 34c to rotate, and sets a conveyance speed difference corresponding to the skew feed amount between the correction roller 34a and the correction roller 34c. Then, the controller 150, while maintaining the conveyance speed difference, drives the correction rollers 34a and 34c for a time period corresponding to the skew feed amount. With this action, the original D is rotated within the conveyance plane, thereby correcting the skew feed of the original D.
In accordance with detection of the trailing edge of the original D by the skew feed detection sensors S1a and S1b, the controller 150 determines a feed timing of a next original by the pickup roller 31. Further, the controller 150 performs size determination for the original D in accordance with detection timings for the leading edge and the trailing edge of the original D by the skew feed detection sensors S1a and S1b.
Next, a specific example of control of the skew feed correction will be described with reference to
ΔT=d/X
The controller 150 calculates the distance d based on a measurement value of the time period ΔT and the known conveyance speed X, and determines the skew feed amount of the original D based on the distance d and the arrangement interval of the skew feed detection sensors S1a and S1b. Then, based on the skew feed amount, the controller 150 determines a conveyance speed difference between the correction rollers 34a and 34c for correction of the skew feed. Then, for example, the controller 150 increases the conveyance speed of the correction roller 34c to be higher than an initial conveyance speed given before the skew feed correction. In this case, the conveyance speed of the correction roller 34a may be maintained at the initial conveyance speed without any change, or the conveyance speed of the correction roller 34a may be reduced to be lower than the initial conveyance speed. Further, both the changes in conveyance speeds of the correction roller 34a and the correction roller 34c may be performed simultaneously.
In any case, the conveyance speed of the correction roller 34b at the center is set to a conveyance speed between the conveyance speed of the correction roller 34a and the conveyance speed of the correction roller 34c. In particular, the conveyance speed of the correction roller 34b is set to a median value. When one roller of the correction rollers 34a and 34c is increased in speed, and another roller is reduced in speed at a rate which is the same as that of the rate of increase in speed of the one roller, the conveyance speed of the correction roller 34b remains at the initial conveyance speed.
The initial conveyance speeds of the correction rollers 34a, 34b, and 34c are equal. Further, when the original D involves skew feed in a direction opposite to that illustrated in
With reference to
At this time, the pickup roller 31, the conveyance roller 32, and the retard roller 33 operate, and the correction rollers 34a, 34b, and 34c rotate at the same speed to wait for the original D. After elapse of a predetermined time period, when none of the skew feed detection sensors S1a and S1b detects the leading edge of the original D (NO in Step S12), the CPU 153 stops all the motors (Step S17), determines that conveyance abnormality due to jamming of the original D has occurred, and informs a user of the jamming of the original (sheet) (Step S19).
When at least one of the skew feed detection sensors S1a and S1b detects the leading edge of the original D before elapse of a predetermined time period (YES in Step S12), the CPU 153 determines whether or not there is a time difference between detections by the skew feed detection sensors S1a and S1b (Step S13). When there is the time difference (YES in Step S13), the CPU 153 calculates a skew feed amount of the original D based on the detection results, and changes rotation speeds of the stepping motors M1 and M2 in accordance with the skew feed amount (Step S18). At this time, the changes in rotation speed of the stepping motors M1 and M2 are maintained for a time period corresponding to the skew feed amount (time difference in Step S13). After elapse of this time period, the rotation speeds of the stepping motors M1 and M2 are set back to speeds which cause the correction rollers 34a and 34c to rotate at the same speed (Step S14).
When there is no time difference between the detections by the skew feed detection sensors S1a and S1b in Step S13, that is, when the skew feed detection sensors S1a and S1b detect the leading edge of the original D at the same time (NO in Step S13), the CPU 153 determines that no skew feed occurs, and continues the rotation of the stepping motors M1 and M2 at the same speed (Step S14).
When the skew feed detection sensors S1a and S1b are not turned off after elapse of the predetermined time period (NO in Step S15), the CPU 153 determines that conveyance abnormality due to jamming of the original D has occurred, and informs a user of the sheet jam (Step S19). At this time, the CPU 153 disengages the feed clutch 59 and turns off supply of power to the stepping motor M1, M2, and M3 to stop conveyance of the original D.
Meanwhile, when the skew feed detection sensors S1a and S1b are turned off before elapse of the predetermined time period (YES in Step S15), the CPU 153 gives the original D to the read rollers 36 and 37. Then, image reading is performed, and thereafter the original D is delivered to the original delivery portion 39 by the delivery roller 38. When there is a next original (YES in Step S16), the CPU 153 continues feeding of the original (Step S11). When there is no next original (NO in Step S16), the feeding is ended.
In the first embodiment, the separation portion E stops conveyance at the timing at which the skew feed detection sensors S1a and S1b detect the original D, and restarts conveyance at the time of starting conveyance of the next original D. During correction of the skew feed by the skew feed correction portion F, the separation portion E is driven to rotate by the original D. Therefore, the separation portion E does not hinder the skew feed correction operation for the original D by the skew feed correction portion F. As long as there is adopted the configuration of not hindering the skew feed correction operation for the original D by the skew feed correction portion F as described above, there may also be adopted a configuration of separating the separation portion E apart to release nipping of the sheet.
In the first embodiment, the correction roller 34b is provided at the intermediate position between the correction rollers 34a and 34c to convey the sheet by the correction roller 34b. Therefore, while the skew feed of the original D is corrected by setting the conveyance speed difference to the correction rollers 34a and 34c, formation of the wrinkles in the original D due to the conveyance resistance or pull-out resistance of the separation portion E can be reduced. In particular, in the first embodiment, the correction roller 34b and the separation portion E are provided at the same position in the width direction orthogonal to the original conveyance direction G. Therefore, a conveyance force resisting against the resistance of the separation portion E can be generated efficiently by the correction roller 34b, and hence the wrinkles are less liable to be formed in the original. Further, the correction roller 34b is positioned at the center between the correction roller 34a and the correction roller 34c. Therefore, conveyance by the correction roller 34b can be performed with less influence on the change in conveyance speed of the correction rollers 34a and 34c for the skew feed correction.
As described above, in the first embodiment, even with the configuration in which the correction rollers 34a and 34c are closely arranged downstream of the separation portion E, pulling of the original by the separation portion E and the skew feed correction portion F can be reduced by the correction roller 34b arranged between the correction rollers 34a and 34c, and hence formation of the wrinkles in the original D is less likely to occur. Therefore, the correction rollers 34a and 34c can be arranged close downstream of the separation portion E, thereby being capable of achieving downsizing of the original conveying apparatus 120.
Further, in the first embodiment, stepping motors, which are excellent in speed responsiveness, are employed as drive sources for the correction rollers 34a, 34b, and 34c. Therefore, detection information of the skew feed detection sensors S1a and S1b can be promptly reflected to a pulse rate change in motor drive pulse. However, the drive sources for the correction rollers 34a, 34b, and 34c are not limited to the stepping motors, and may be other motors such as DC motors.
A second embodiment of the present invention will be described with reference to
In the second embodiment, the skew feed detection sensors S1a and S1b are arranged downstream of the correction rollers 34a, 34b, and 34c in the original conveyance direction G. The skew feed detection sensors S1a and S1b are arranged apart from each other by a predetermined interval in the width direction H so that respective detection positions for detecting the leading edge of the original are positioned on the same straight line parallel to the width direction H orthogonal to the original conveyance direction G.
In the second embodiment, under a state in which the original D is nipped by the correction rollers 34a, 34b, and 34c and being conveyed, the skew feed amount of the original D is detected by the skew feed detection sensors S1a and S1b. Therefore, the skew feed amount of the original D can be detected under a state in which the conveyance state is more stable than that in the first embodiment in which the skew feed amount of the original D being conveyed by the separation portion E is detected, thereby being capable of performing more accurate skew feed correction.
In the second embodiment, the skew feed detection sensors S1a and S1b detect the skew feed amount of the sheet being conveyed by at least the correction roller 34b. Therefore, the skew feed amount can be detected under a state in which an edge having been alleviated in warpage through conveyance by the correction roller 34b is linear, thereby being capable of controlling the skew feed correction by the correction roller 34a and the correction roller 34c based on output from the stable skew feed detection sensors S1a and S1b.
In the second embodiment, a conveyance distance from passage of the leading edge of the original D through the skew feed detection sensors S1a and S1b to passage of the trailing edge of the original D through the correction rollers 34a, 34b, and 34c is short. Therefore, when the skew feed amount of the original D having a small length in the original conveyance direction G is to be corrected, there is a fear in that the skew feed correction is not completed before the trailing edge of the original D passes through the correction rollers 34a, 34b, and 34c. Therefore, in the case of the original D having a small length in the original conveyance direction G, it is preferred that nip time required for the skew feed correction be secured by reducing the conveyance speed.
A third embodiment of the present invention will be described with reference to
In the third embodiment, the skew feed detection sensors S1a and S1b are arranged upstream of the correction rollers 34a, 34b, and 34c in the original conveyance direction G. The skew feed detection sensors S1a and S1b are arranged apart from each other by a predetermined interval in the width direction H so that respective detection positions for detecting the leading edge of the original D are positioned on the same straight line parallel to the width direction H orthogonal to the original conveyance direction G.
As illustrated in
The first drive transmission portion 71 transmits drive from the stepping motor M11 to the planetary gear mechanisms 60a and 60c. Specifically, the drive transmission portion 71 includes a pulley 25e fixed to a rotary shaft of the stepping motor M11, pulleys 25c and 25a fixed to shafts of the planetary gear mechanisms 60a and 60c on drive input side, respectively, and a belt 27e stretched around the pulleys 25e, 25c, and 25a.
The second drive transmission portion 72 also transmits drive from the stepping motor M12 to the planetary gear mechanisms 60a and 60c. Specifically, the second drive transmission portion 72 includes a gear 26 fixed to a rotary shaft of the stepping motor M12, and the gear 26 is in mesh with an outer gear portion 64, which will be described later and is formed on an outer peripheral surface of a ring gear 66a of the planetary gear mechanism 60a described later. The outer gear portion 64a of the ring gear 66a is in mesh with an outer gear portion 64c, which is adjacent to the outer gear 64a and is formed on an outer peripheral surface of a ring gear 66c of the planetary gear mechanism 60c.
(Planetary Gear Mechanism)
A description will be provided of the above-mentioned planetary gear mechanisms 60a and 60c with reference to
The sun gear 61 is fixed to each of the rotary shafts 610a and 610c. As illustrated in
The ring gear 66 is a cylindrical gear which is arranged so as to be coaxial with the sun gear 61 and surround a periphery of the sun gear 61, and has an inner gear portion 65 on an inner peripheral surface and the outer gear portion 64 on an outer peripheral surface. As described above, the outer gear portion 64a of the planetary gear mechanism 60a and the outer gear portion 64c of the planetary gear mechanism 60c are in mesh with each other.
In a space formed between the sun gear 61 and the ring gear 66, a plurality of (two in the illustrated example) planetary gears 62 are arranged so as to be in mesh with the sun gear 61 and the inner gear portion 65. Respective rotary shafts of the plurality of planetary gears 62 are supported by the carrier 63. Therefore, the planetary gears 62 are rotatable about respective axes, and are revolvable together with the carrier 63 around the sun gear 61. A rotation center shaft 630 of the carrier 63 is coaxial with a rotation center shaft of the sun gear 61, and is connected to the first drive transmission portion 71. That is, a rotation center shaft 630a of the planetary gear mechanism 60a is fixed to the pulley 25a of the first drive transmission portion 71. A rotation center shaft 630c of the planetary gear mechanism 60c is fixed to the pulley 25c of the first drive transmission portion 71.
The third drive transmission portion 80 is capable of transmitting the drive of the stepping motor M11 to the correction roller 34b being the third conveyance rotary member without intermediation of the speed-changing portion 70. Specifically, the third drive transmission portion 80 includes a pulley 25b around which the belt 27e is stretched, a pulley 25f connected to the pulley 25b through intermediation of the rotary shaft 81, a pulley 25g fixed to the rotary shaft of the correction roller 34b, and a belt 27f stretched around the pulleys 25f and 25g. Thus, the drive of the stepping motor M11 is transmitted to the correction roller 34b through intermediation of the pulley 25e, the belt 27e, the pulley 25b, the rotary shaft 81, the pulley 25f, the belt 27f, and the pulley 25g.
The drive of the stepping motor M11 is transmitted also to carriers 63a and 63c of the planetary gear mechanisms 60a and 60c through intermediation of the pulley 25e, the belt 27e, and the pulleys 25a and 25c. The planetary gears 62a and 62c revolve together with the carriers 63a and 63c so that the sun gears 61a and 61c rotate. The rotation of the sun gear 61a is transmitted to the correction roller 34a through intermediation of the rotary shaft 610a, the pulley 25h, the belt 27h, and the pulley 25i. The rotation of the sun gear 61c is transmitted to the correction roller 34c through intermediation of the rotary shaft 610c, the pulley 25j, the belt 27j, and the pulley 25k.
As described above, the drive of the stepping motor M12 is transmitted to the outer gear portion 64a of the ring gear 66a of the planetary gear mechanism 60a through intermediation of the gear 26. Further, the drive of the stepping motor M12 is transmitted from the outer gear portion 64a to the outer gear portion 64c of the ring gear 66c of the planetary gear mechanism 60c. The outer gear portions 64a and 64c are directly in mesh with each other, and hence rotation directions of the ring gears 66a and 66c are opposite to each other.
Thus, when the stepping motor M12 rotates, due to different rotation directions of the ring gears 66a and 66c, the drive transmitted to the sun gears 61a and 61c through intermediation of the inner gear portions 65a and 65c and the planetary gears 62a and 62c acts so as to increase one of the sun gears 61a and 61c in speed and reduce another of the sun gears 61a and 61c in speed in accordance with the rotation direction of the stepping motor M12. Therefore, through transmission of the drive of the stepping motor M12 in superposition with the drive of the stepping motor M11, the speed-changing portion 70 is capable of changing the rotation speeds of the sun gears 61a and 61c. As described above, the sun gears 61a and 61c are connected to the correction rollers 34a and 34c, respectively. Therefore, through changes in rotation speed of the sun gears 61a and 61c, a speed difference can be set between the correction roller 34a and the correction roller 34c.
Specifically, when the stepping motor M12 is stopped, the drive of the stepping motor M11 causes a rotation speed equal to the rotation speeds of the carriers 63a and 63c to be output to the sun gears 61a and 61c. With this action, the correction rollers 34a and 34c rotate at the same speed in the same direction.
When the stepping motor M12 rotates, for example, a rotation speed which is obtained by adding the rotation speed of the ring gear 66a to the rotation speed of the carrier 63a is output to the sun gear 61a. Meanwhile, a rotation speed which is obtained by subtracting the rotation speed of the ring gear 66c from the rotation speed of the carrier 63c is output to the sun gear 61c. With those actions, a speed difference is set to the conveyance speeds of the correction rollers 34a and 34c.
The conveyance speed of the correction roller 34b is set so as to be equal to the conveyance speeds of the correction rollers 34a and 34c given when the stepping motor M12 is stopped. Further, when the speed difference is set to the correction rollers 34a and 34c by rotation of the stepping motor M12, the conveyance speed of the correction roller 34b is set to a conveyance speed between the conveyance speed of the correction roller 34a and the conveyance speed of the correction roller 34c. In particular, in the third embodiment, the conveyance speed of the correction roller 34b is set to a median value.
(Skew Feed Correction Control)
With reference to
At this time, the pickup roller 31, the conveyance roller 32, and the retard roller 33 operate, and the correction rollers 34a, 34b, and 34c rotate at the same speed to wait for the original D. After elapse of a predetermined time period, when none of the skew feed detection sensors S1a and S1b detects the leading edge of the original D (NO in Step S22), the CPU 153 determines that conveyance abnormality due to jamming of the original D has occurred, stops the stepping motor M11 (Step S26), and informs a user of the jamming of the original (sheet) (Step S28).
When at least one of the skew feed detection sensors S1a and S1b detects the leading edge of the original D before elapse of a predetermined time period (YES in Step S22), the CPU 153 determines whether or not there is a time difference between detections by the skew feed detection sensors S1a and S1b (Step S23). When there is the time difference (YES in Step S23), the CPU 153 calculates a skew feed amount of the original D based on the detection results, and rotates the stepping motor M12 in accordance with the skew feed amount (Step S27). At this time, the rotation of the stepping motor M12 is maintained for a time period corresponding to the skew feed amount (time difference in Step S23). After elapse of this time period, the rotation of the stepping motor M12 is stopped.
When there is no time difference between the detections by the skew feed detection sensors S1a and S1b, that is, when the skew feed detection sensors S1a and S1b detect the leading edge of the original D at the same time (NO in Step S23), the CPU 153 determines that no skew feed occurs, and continues the rotation of the stepping motor M11 at the same speed and stops the stepping motor M12.
When the skew feed detection sensors S1a and S1b are not turned off after elapse of the predetermined time period (NO in Step S24), the CPU 153 determines that conveyance abnormality due to jamming of the original D has occurred, and informs a user of the sheet jam (Step S28). At this time, the CPU 153 disengages the feed clutch 59 and turns off supply of power to the stepping motor M11 to stop conveyance of the original D.
When the skew feed detection sensors S1a and S1b are turned off before elapse of the predetermined time period (YES in Step S24), the CPU 153 gives the original D to the read rollers 36 and 37. Then, image reading is performed, and thereafter the original D is delivered to the original delivery portion 39 by the delivery roller 38. When there is a next original (YES in Step S25), the CPU 153 continues feeding (Step S21). When there is no next original (NO in Step S25), the feeding is ended.
In the third embodiment, the speed difference of the conveyance speeds of the correction rollers 34a and 34c is set through use of the planetary gear mechanisms 60a and 60c, and hence speed control of the correction rollers 34a and 34c can be performed through use of two motors. Further, of the two motors, the stepping motor M11 for driving the correction rollers 34a and 34c can be used also for driving of the correction roller 34b. Therefore, even with the configuration in which three conveyance rotary members are provided, the number of motors being drive sources may be two.
Further, in the third embodiment, while the correction rollers 34a and 34c are rotated by the stepping motor M11, speed adjustment for the skew feed correction can be performed with respect to the correction rollers 34a and 34c through use of the stepping motor M12. Therefore, as compared to the case of the first embodiment in which the correction rollers 34a and 34c are rotated by independent motors, respectively, synchronization of the correction rollers 34a and 34c in rotation, stoppage, acceleration, and deceleration can easily be performed, thereby being capable of suppressing variation in rotation speed of the correction rollers 34a and 34c and in timing of starting and stopping rotation of correction rollers 34a and 34c. For example, stoppage and start of the rotation of the correction rollers 34a and 34c can be performed through stoppage and activation of one stepping motor M11. Therefore, as compared to the case of synchronizing stoppage or activation of a plurality of motors, the operations of the correction rollers 34a and 34c can easily be synchronized, and conveyance control can be performed more accurately.
A fourth embodiment of the present invention will be described with reference to
In the fourth embodiment, the skew feed detection sensors S1a and S1b are arranged downstream of the correction rollers 34a, 34b, and 34c in the original conveyance direction G. The skew feed detection sensors S1a and S1b are arranged apart from each other by a predetermined interval in the width direction H so that respective detection positions for detecting the leading edge of the original D are positioned on the same straight line parallel to the width direction H orthogonal to the original conveyance direction G.
Similarly to the second embodiment, in the fourth embodiment, under a state in which the original D is nipped by the correction rollers 34a, 34b, and 34c and being conveyed, the skew feed amount of the original D is detected by the skew feed detection sensors S1a and S1b. Therefore, the skew feed amount of the original D can be detected under a state in which the conveyance state is more stable than that in the third embodiment in which the skew feed amount of the original D being conveyed by the separation portion E is detected, thereby being capable of performing more accurate skew feed correction. Other actions and effects are the same as those of the second embodiment.
A fifth embodiment of the present invention will be described with reference to
(Image Forming Apparatus)
As illustrated in
The image forming unit 220 includes a charge roller 222, an exposure device 223, a developing device 224, a transfer roller 225, and a drum cleaning device 226, which are arranged around a photosensitive drum 211. The charge roller 222 charges a peripheral surface of the photosensitive drum 221 to a uniform potential. The exposure device 223 scans and exposes the photosensitive drum 221 with use of a laser beam modulated in accordance with information of an image to be formed, to thereby form an electrostatic latent image on the photosensitive drum 221.
The developing device 224 develops an electrostatic latent image on the photosensitive drum 221 with toner (developer), to thereby form a toner image on the photosensitive drum 221. The transfer roller 225 receives a transfer voltage applied thereto, and transfers the toner image on the photosensitive drum 221 to the sheet P having been fed from the feeding unit 210. The drum cleaning device 226 cleans the photosensitive drum 221 after the transfer of the toner image onto the sheet P.
The sheet P having the toner image transferred thereto is conveyed to the fixing device 230 and is heated and pressurized by the fixing device 230 so that the image is fixed thereon. After that, the sheet P is delivered to a predetermined delivery tray.
(Feeding Unit)
The feeding unit 210 picks up the sheets P stacked in a cassette 211 one after another and conveys the sheets P to the image forming unit 220. As described above in relation to the step in which the sheet P is nipped and conveyed in the image forming unit 220, the toner image is transferred to the sheet P.
The pickup roller 212 rotates while being held in abutment against an upper most sheet P stacked in the cassette 211, to thereby feed the sheet P from the cassette 211 and convey the sheet P to the separation portion E1.
The separation portion E1 includes a conveyance roller 32A, which rotates in a sheet conveyance direction, and a retard roller 33A, which forms a separation nip with the conveyance roller 32A. The retard roller 33A is driven in a direction of conveying the sheet in a direction opposite to the sheet conveyance direction of the conveyance roller 32A, and is capable of being driven by the conveyance roller 32A. At such separation portion E1, while the conveyance roller 32A conveys the sheet P on an uppermost surface to the skew feed correction portion F2 downstream of the separation portion E1, the retard roller 33A pushes back a multi-fed sheet, which is fed together with the sheet P, to the cassette 211. Further, when one sheet is conveyed to the separation portion E1, the retard roller 33A is driven by the conveyance roller 32A to rotate, thereby conveying the sheet to the skew feed correction portion F2.
Similarly to
The sheet conveying apparatus according to the present invention is not limited to the specific configurations described in the first to fourth embodiments. The present invention may be implemented with other embodiments in which part or all of the configurations of the first to fourth embodiments are replaced with equivalent members. The first conveyance rotary member, the second conveyance rotary member, and the third conveyance rotary member may be replaced with a conveyance belt stretched around a plurality of conveyance rollers or support rollers.
In the first to fifth embodiments, the correction roller 34b being the third conveyance rotary member is arranged downstream of the separation portion in the sheet conveyance direction. However, the place of arrangement of the correction roller 34b is not limited to downstream of the separation portion. For example, the correction roller 34b may be arranged, for example, at a position far apart to downstream from the separation portion E, a position downstream of a source of generation of the conveyance resistance which is different from the separation portion E, or a position downstream of the conveyance means different from the separation portion E.
In the first to fifth embodiments, a description will be provided of the configuration in which the correction rollers 34a and 34c are arranged on both sides of the sheet in the width direction orthogonal to the conveyance direction, respectively, to correct the skew feed of the sheet. However, the present invention is also applicable to a configuration in which a plurality of (for example, two) correction rollers are arranged on each of both sides in the width direction to correct the skew feed of the sheet. For example, when two correction rollers are arranged on each of both sides in the width direction, the two correction rollers on one side in the width direction may be considered as one first conveyance rotary member, and the two correction rollers on another side in the width direction may be considered as one second conveyance rotary member. Thus, in this case, one or a plurality of correction rollers being the third conveyance rotary member is arranged between the first conveyance rotary member and the second conveyance rotary member.
For example, respective correction rollers arranged upstream of the first conveyance rotary member and the second conveyance rotary member in the sheet conveyance direction are assumed to be a pair of upstream rollers. Similarly, respective correction rollers arranged downstream in the sheet conveyance direction are assumed to be a pair of downstream rollers. In this case, one correction roller being the third conveyance rotary member may be arranged between the pair of upstream rollers and between the pair of downstream rollers. Alternatively, one correction roller being the third conveyance rotary member may be arranged at a center of the pair of upstream rollers and the pair of downstream rollers in the sheet conveyance direction and at a center between the first conveyance rotary member and the second conveyance rotary member.
In the first to fifth embodiments, a description will be provided of the configuration in which the correction roller 34b being the third conveyance rotary member is driven by the motor. However, the correction roller 34b may be driven to rotate along with conveyance of the sheet, rather than being driven by the motor. Even with such configuration, the sheet can be pressed by the correction roller 34b between the correction rollers 34a and 34c. Therefore, as compared to the case in which the correction roller 34b is not provided, wrinkles formed in the sheet which are caused by, for example, the pull-out resistance at the separation portion can be reduced.
In the third and fourth embodiments, the planetary gear mechanism is used to change the conveyance speed difference of the correction rollers 34a and 34c. However, a differential mechanism other than the planetary gear mechanism may be used. For example, a bevel gear differential mechanism may be used.
In the third and fourth embodiments, a description will be provided of the planetary gear which is designed so that the correction rollers 34a and 34c driven by the stepping motor M11 rotate at the same rotation speed under a state in which the stepping motor M12 is stopped. However, the planetary gear mechanism may be designed so that the correction rollers 34a and 34c rotate at the same rotation speed under a state in which the stepping motor M12 rotates at a predetermined rotation speed V. At this time, the planetary gear mechanism can be designed so that the conveyance speed difference is set to the correction roller 34a and 34c by changing the rotation speed V of the stepping motor M12 to ±ΔV. The selection and layout of the drive gear and the planetary gear in the planetary gear mechanism as well as detailed structure thereof can be changed or corrected in design in various manners within the scope of the claims at the time of actual implementation.
The sheet conveying apparatus according to the embodiments may be applied to various portions along the conveyance passage of the sheet in various apparatus other than original conveying apparatus to be mounted to, for example, a copying machine, a scanner, or a facsimile machine. As described in the fifth embodiment, the sheet conveying apparatus may be applied to the feeding unit, which is mounted to the image forming apparatus and is configured to convey an unused sheet. The sheet conveying apparatus may be applied to, for example, a copying machine, a printer, a facsimile, and various printing machines to feed a sheet having been subjected to the skew feed correction to the image forming unit. The sheet conveying apparatus according to the present invention may be applied to a sheet processing apparatus configured to perform sheet processing such as aligning and stacking of sheets, book binding, punching, and stapling to feed a sheet having been subjected to skew feed correction to a sheet processing unit.
In the sheet conveying apparatus according to the embodiments, wrinkles are less liable to be formed in the sheet during sheet conveyance.
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. 2017-056177, filed Mar. 22, 2017, and Japanese Patent Application No. 2018-022280, filed Feb. 9, 2018, which are hereby incorporated by reference herein in their entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2017-056177 | Mar 2017 | JP | national |
| 2018-022280 | Feb 2018 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 4430606 | Otsuki | Feb 1984 | A |
| 5156391 | Roller | Oct 1992 | A |
| 9828200 | Kuwata | Nov 2017 | B2 |
| 20140232055 | Yamagata | Aug 2014 | A1 |
| 20170050812 | Mukai | Feb 2017 | A1 |
| Number | Date | Country |
|---|---|---|
| H05-201587 | Aug 1993 | JP |
| H09-24436 | Jan 1997 | JP |
| 2003-312900 | Nov 2003 | JP |
| 2010-042903 | Feb 2010 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20180273319 A1 | Sep 2018 | US |
