JP4046993B2 - Sheet feeding apparatus and image forming apparatus provided with the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sheet feeding apparatus and an image forming apparatus including the sheet feeding apparatus, and more particularly to control for maintaining a predetermined interval between sheets.
[0002]
[Prior art]
The conventional image forming apparatus includes a sheet feeding device that feeds the sheet stored in the sheet storage unit by the sheet feeding unit and then transports the sheet to the image forming unit by the sheet transport unit. As such a sheet feeding device, there is one provided with means for adjusting the interval between continuously conveyed sheets to a predetermined interval.
[0003]
Here, as such a sheet interval adjusting means, an adjusting unit for adjusting the sheet interval is provided, and after the preceding sheet passes through the adjusting unit, the succeeding sheet is passed through the adjusting unit at an interval narrower than a predetermined interval. In addition to feeding, the leading edge of the succeeding sheet is detected by a sensor provided on the conveyance path, and the succeeding sheet is stopped for a predetermined time using the detection timing to adjust the interval with the preceding sheet.
[0004]
[Problems to be solved by the invention]
However, in the conventional sheet feeding apparatus using such a sheet interval adjusting method, the succeeding sheet is fed to the preceding sheet, and the interval between the downstream preceding sheet and the upstream succeeding sheet is extremely small. If it becomes narrower or a double feed occurs in which the trailing edge of the preceding sheet and the leading edge of the succeeding sheet are overlapped, the sensor cannot detect the leading edge of the upstream succeeding sheet. .
[0005]
If it becomes impossible to detect the leading edge of the succeeding sheet in this way, it becomes impossible to calculate the stop time of the succeeding sheet, and it becomes impossible to adjust the sheet interval.
[0006]
Further, as a means for adjusting the sheet interval to a predetermined interval as described above, when a configuration is adopted in which the succeeding sheet is fed in advance so as to be shorter than the predetermined interval upstream from the adjustment unit, it is too short. If the succeeding sheets are fed at intervals, the sheet interval detection becomes more difficult, and there is a practical limit.
[0007]
Therefore, the present invention has been made in view of such a current situation, and a sheet feeding apparatus capable of performing proper sheet interval adjustment even when double feeding or the like occurs in a sheet, and an image including the sheet feeding apparatus. An object of the present invention is to provide a forming apparatus.
[0008]
[Means for Solving the Problems]
The present invention includes a sheet feeding unit that feeds out a sheet stored in a sheet storage unit, a sheet conveying unit that can forward / reverse the sheet fed by the sheet feeding unit, and a sheet conveying unit that can perform forward / reverse rotation. And a detection signal for detecting the next sheet after the detection signal for detecting the sheet is input from the sheet detection means. If input earlier than the predetermined timing, the aforementioned backhaul to was reverse rotation by said next sheet reversible sheet conveying means is adjusted to increase the distance of the sheet and the next sheet sheet And an interval adjusting means.
[0010]
In the invention, it is also possible that the sheet interval adjusting unit is capable of rotating the sheet forward and backward at a timing at which the sheet interval becomes a predetermined interval when the sheet detecting unit detects the leading edge of the next reversely fed sheet. It is characterized by resuming normal rotation of.
[0011]
Further, the present invention is characterized in that the timing of detecting the leading edge of the next reversely fed sheet by the sheet detecting means is limited to a predetermined error range.
[0013]
In the present invention, at least one of a sheet conveyance speed at the time of forward rotation and a sheet conveyance speed at the time of reverse rotation of the sheet conveyance means capable of forward / reverse rotation is variable, and the sheet interval adjustment means When the distance between the sheet and the next sheet cannot be adjusted due to the reverse rotation, the ratio of the sheet conveyance speed during the forward rotation and the reverse rotation is changed.
[0014]
In the invention, it is preferable that the sheet interval adjusting unit is based on a conveyance direction length of the sheet, a sheet conveyance speed during normal rotation of the sheet conveyance unit capable of forward / reverse rotation, and a predetermined interval between the sheet and the next sheet. The sheet conveying speed at the time of reverse rotation is determined.
[0015]
The present invention includes a sheet feeding means for feeding the sheets stored in the sheet storage portion, a sheet conveying means for conveying the sheet fed by said sheet feeding means, the sheet fed by said sheet feeding means A reverse feed unit configured to rotate in a direction to return to the sheet storage unit, and to rotate with the rotation of the sheet conveyance unit, and provided downstream of the sheet conveyance unit and conveyed by the sheet conveyance unit a sheet detecting means for detecting the sheet, after the detection signal detected the sheet from said sheet detecting means is inputted, when a detection signal obtained by detecting the next sheet is input earlier than the predetermined timing, the to backhaul the next sheet by the backhaul means stops the rotation of the sheet conveying means, to adjust to widen the distance between the sheet and the next sheet It is characterized in that it comprises a sheet interval adjusting means.
[0017]
In the invention, it is preferable that the sheet interval adjusting unit restarts the rotation of the sheet conveying unit when the sheet detecting unit detects the leading edge of the next sheet that has been reversely fed.
[0018]
Further, the present invention is characterized in that the timing of detecting the leading edge of the next reversely fed sheet by the sheet detecting means is limited to a predetermined error range.
[0020]
In the present invention, at least one of a sheet conveying speed of the sheet conveying means and a reverse speed of the reverse feeding means is variable, and the sheet interval adjusting means is configured to perform the reverse feeding by the reverse feeding means and the sheet and the next sheet. When the interval cannot be adjusted, the ratio of the sheet conveying speed of the sheet conveying means and the reverse speed of the reverse feeding means is changed.
[0021]
In the invention, it is preferable that the sheet interval adjusting unit is configured to reversely feed the reverse unit based on a length of the sheet in the conveyance direction, a sheet conveyance speed of the sheet conveyance unit, and a predetermined interval between the sheet and the next sheet. It is characterized by determining the speed.
[0022]
According to the present invention, an image forming apparatus includes the image forming unit and the sheet feeding device according to any one of the above that feeds the sheet to the image forming unit.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0024]
FIG. 1 is a diagram illustrating a configuration of a sheet feeding apparatus according to a first embodiment of the present invention. The sheet feeding apparatus includes a cassette 8 that is a sheet storage unit that stores sheets P such as cut sheets, and the like. A pickup roller 7 that is a sheet feeding means for feeding the sheet P from the cassette 8, a pickup roller vertical movement drive source 12 that moves the pickup roller 7 up and down, and a first transport roller that feeds out the sheet P picked up by the pickup roller 7. 2 and a second transport roller 11 provided downstream of the first transport roller 2. Reference numeral 1 denotes a roller that contacts the first conveying roller 2.
[0025]
Further, the sheet feeding apparatus includes a control unit 50 for controlling the sheet feeding operation. When the sheet feeding operation is started by the control of the control unit 50, first, the pickup roller vertical movement drive source 12 is operated. As a result, the pickup roller 7 located above the cassette 8 is lowered and pressed onto the sheet P. Then, when the pickup roller 7 rotates in this state, the sheet P is sent out to the first conveying roller 2.
[0026]
Next, the sheet P sent to the first conveying roller 2 which is a sheet conveying means capable of forward and reverse rotation provided in the conveying path 4 by the pickup roller 7 in this way is the first sheet positioned downstream by the first conveying roller 2. 2 is conveyed to the conveyance roller 11. Then, when the sheet P is provided by the second conveying roller 11, for example, when the sheet feeding apparatus is provided in an image forming apparatus that forms an image by an electrophotographic method, the sheet P is not shown. It is conveyed to the image forming unit.
[0027]
Here, the pickup roller 7 is selectively rotated by the first drive source 6 and the clutch 10, and the first transport roller 2 is rotated by the second drive source 5. Further, the second transport roller 11 is rotated by the third drive source 9. Note that the first transport roller 2 normally rotates in the direction in which the sheet P is transported to the second transport roller 11 at the same rotational speed as the pickup roller 7.
[0028]
Further, stepping motors are used for the first to third drive sources 5, 6, and 9. In the present embodiment, the first to third drive sources 5, 6, and 9 are independent of each other. However, the configuration is not particularly limited.
[0029]
By the way, the sheet feeding apparatus includes a sheet feeding sensor 3 which is a sheet detecting unit downstream of the first conveying roller 2 as shown in FIG. In the present embodiment, the paper feed sensor 3 detects that the sheet P is present at the detection position when the light shielding plate (not shown) shields the photo interrupter (not shown) by contacting the sheet P, for example. The thing of the structure to use is used.
[0030]
The paper feed sensor 3 is arranged so as to detect the presence or absence of a sheet in the vicinity of the downstream side of the first conveying roller 2, and the sheet detection information is input to the control device 50 which is a sheet interval adjusting means. Like to do.
[0031]
Here, after the preceding sheet has passed, the control device 50 samples (takes in) the signal from the paper feed sensor 3 at a predetermined timing, so that the sheet P is conveyed, for example, (a) in FIG. The preceding sheet P1 and the succeeding sheet P2 which is the next sheet are normally conveyed, the succeeding sheet P2 shown in (b) is pushed in, and the preceding sheet P1 and succeeding shown in (c) It is possible to detect three states: a state in which double feeding occurs in the sheet P2.
[0032]
In the present embodiment, the controller 50 detects the conveyance delay of the preceding sheet P1 at the timing T0 when the trailing edge of the preceding sheet P1 passes through the sheet feeding sensor 3 after the sheet feeding sensor 3 detects the leading edge of the preceding sheet P1. From the point of time when α is added, the signal from the paper feed sensor 3 is sampled at a predetermined period t1.
[0033]
Here, when the sheets P1 and P2 are being conveyed normally, after the paper feed sensor 3 detects the trailing edge of the preceding sheet P1, the interval between the preceding sheet P1 and the succeeding sheet P2 is a predetermined interval. When the control device 50 operates the clutch 10 at a timing such that the interval becomes narrower, the leading edge of the succeeding sheet P2 is detected at a predetermined timing T1 when the succeeding sheet P2 is normally conveyed. Become.
[0034]
On the other hand, as shown in FIG. 2B, when the trailing sheet P2 is plunged, the leading edge of the trailing sheet P2 is at a predetermined timing T1 when the trailing sheet P2 is normally conveyed. Until the sheet feed sensor 3 detects the leading edge of the succeeding sheet P2. Also, as shown in FIG. 2C, when double feeding occurs, the paper feed sensor 3 detects the succeeding sheet P2 at the time T0 + α.
[0035]
Here, when the thrust of the succeeding sheet P2 or the double feeding is detected by the detection timing of the succeeding sheet P2 by the sheet feeding sensor 3, the control device 50 reverses the second drive source 5 and reverses it. The row sheet P2 is reversely fed, and the subsequent sheet P2 is separated or separated from the preceding sheet P1 conveyed downstream by the second conveyance roller 11.
[0036]
If the detection signal from the paper feed sensor 3 sampled at the cycle t1 is not input after the backward sheet P2 is thus reversely fed, the reverse feeding is terminated at this point. Then, after the reverse feeding is completed in this way, the second drive source 5 is rotated forward at a predetermined timing, so that the succeeding sheet P2 is positioned at a desired predetermined interval with respect to the preceding sheet P1. Can be transported again.
[0037]
3 and 4 are diagrams showing a flow from detection of double feeding to adjustment to a desired predetermined sheet interval. As shown in FIG. 3A, the succeeding sheet P1 is followed by a succeeding sheet. When P2 is double fed and detected by a signal from the paper feed sensor 3, the control device 50 reversely feeds the succeeding sheet P2 by reversing the second drive source 5 as shown in FIG. .
[0038]
Then, when the succeeding sheet P2 that has been reversely fed passes through the paper feed sensor 3 and is detected by a signal from the paper feed sensor 3, the second drive source 5 as shown in FIG. Thereafter, as shown in FIG. 4B, the second drive source is driven at such a timing that the distance between the trailing edge of the preceding sheet P1 and the leading edge of the succeeding sheet P2 becomes a desired predetermined distance. 5 is driven and the first conveying roller 2 is restarted. Thereby, the succeeding sheet P2 is conveyed while forming a predetermined interval with respect to the preceding sheet P1.
[0039]
Thus, based on the timing at which the succeeding sheet detection signal from the sheet feeding sensor 3 is input, by selectively reversely rotating the first conveying roller 2 that can be rotated forward and backward, the succeeding sheet P2 is reversely fed. Even when double feeding or the like occurs, appropriate sheet interval adjustment can be performed.
[0040]
By the way, since the second drive source 5 does not stop immediately after the passage of the succeeding sheet P1 to which the paper feed sensor 3 is reversely fed is actually detected, the subsequent drive is continued until the second drive source 5 stops. The sheet P2 is fed backward. Further, as described above, since the paper feed sensor 3 is sampled at the cycle t1, the succeeding sheet P2 may pass through the paper feed sensor 3 immediately after the sampling is completed.
[0041]
In this case, since the succeeding sheet P2 is not detected until the next sampling is performed, it is assumed that the feed sensor 3 detects the passage of the succeeding sheet P2 based on the reverse feed speed p of the succeeding sheet P2. As shown in FIG. 5, the position is separated from the detection position of the paper feed sensor 3 by p * t1.
[0042]
Therefore, when the above-described control is performed, an error corresponding to the total of the transport distance p * t1 and the distance L transported until the second drive source 5 shown in FIG. However, this error can be reduced by narrowing the sampling period t1 and suppressing the conveyance distance L during stoppage.
[0043]
Further, by reducing the sheet detection error by the paper feed sensor 3 in this way, the leading edge of the succeeding sheet P2 can be brought close to the detection position of the paper feed sensor 3, and the distance from the preceding sheet P1 can be accurately ensured. It becomes possible to do.
[0044]
If the leading edge of the succeeding sheet P2 cannot detect the passage of the succeeding sheet P2 to be reversely fed until the timing T1 when the succeeding sheet P2 is normally conveyed, the succeeding sheet P2 is further followed. When the sheet P2 is reversely fed, the sheet interval is too wide. Therefore, the device is stopped to prevent this, or the reverse feeding is stopped and the normal conveyance of the subsequent sheet P2 is started, or the conveyance timing is changed and the subsequent sheet is changed. Options such as resuming normal conveyance at the timing when the rear end passage of P2 can be detected can be considered.
[0045]
As in this embodiment, after the succeeding sheet P2 is sent out at a narrower interval than the desired predetermined sheet interval, the succeeding sheet P2 is stopped, or when the double feeding or the like occurs By configuring the row sheet P2 to be fed backward, it is not necessary to use a paper feed sensor 3 having a high detection accuracy, so that the cost can be reduced.
[0046]
FIG. 6 is a flowchart illustrating an example of sheet interval adjustment control according to the present embodiment. As illustrated in FIG. 6, when T0 + α elapses after feeding is started (S101, S102), first, the following process is performed. The paper feed sensor 3 is sampled every cycle t1 until a predetermined timing T1 when the sheet P2 is normally conveyed (S103, S110).
[0047]
Next, when the paper feed sensor 3 detects the passage of the leading edge of the succeeding sheet P2 until the predetermined timing T1 is reached (Y in S111), the second conveying roller 11 is reversely rotated to start reverse feeding (S112). ). After this, when T1 elapses, the second transport roller 11 is rotated forward (Y in S113, S104, S105).
[0048]
Further, if the leading edge of the backward sheet P2 to be reversely fed cannot be detected by the time T1 elapses, if the backward sheet P2 is further fed backward, the sheet interval is excessively widened to prevent this. The device is stopped (S113, S114, S115).
[0049]
Next, a second embodiment of the present invention will be described.
[0050]
FIG. 7 is a diagram illustrating a configuration of the sheet feeding apparatus according to the present embodiment. In the figure, the same reference numerals as those in FIG. 1 denote the same or corresponding parts.
[0051]
In the figure, reference numeral 102 denotes a first conveying roller which is a conveying means for feeding out a sheet picked up by the pickup roller 7, and 101 is arranged so as to contact the first conveying roller 102 and rotates in a direction to return to the cassette 8. On the other hand, a retard roller 104, which is a reverse feeding means configured to rotate with the rotation of the first conveying roller 102, is a torque limiter for controlling the rotation direction of the retard roller 101.
[0052]
Here, the rotation of the first conveying roller 102 is performed by the same first driving source 6, the same clutch 10 and the pickup roller 7. Further, the retard roller 101, pickup roller 7, carried out by the same first drive source 6 and the first conveying roller 102, in this embodiment, the second conveying roller 11 first conveying roller 102 and the pickup roller As in FIG. 7, it is driven by the first drive source 6. With this configuration, it is possible to reduce the number of drive system parts and to reduce costs.
[0053]
Further, in the present embodiment, the retard roller 101 rotates in the sheet conveying direction because it exceeds the limit of the torque limiter 104 when the first conveying roller 102 is driven by the first driving source 6 via the clutch 10. When the first conveying roller 102 is not driven, it is configured to rotate in the reverse direction in order to prevent the trailing sheet P2 from being pushed in or double feeding.
[0054]
In the sheet feeding apparatus having such a configuration, when the sheet feeding operation is started, the pickup roller 7 is first lowered and pressed onto the sheet P. Then, when the pickup roller 7 rotates in this state, the sheet P is sent out to the first conveying roller 102.
[0055]
Next, the sheet P sent out to the first conveyance roller 102 by the pickup roller 7 in this way is conveyed to the second conveyance roller 11 and then conveyed to an image forming unit (not shown).
[0056]
By the way, when the second transport roller 11 is driven by the first drive source 6 as in the present embodiment, the second transport roller 11 must always be normally rotated. Cannot be stopped or reversed. If the first drive source 6 is stopped or reversed, the leading edge of the sheet may vary between the leading edge of the sheet in the cassette and the nip between the retard roller 101 and the first conveying roller 102. is there.
[0057]
Therefore, in the present embodiment, when the double feed and the thrust are detected by the paper feed sensor 3 in the same manner as in the first embodiment described above, the double feed and the thrust are detected in this way. The control device 50 turns off the clutch 10 at the stage where the conveyance of the succeeding sheet is started, and reversely feeds the succeeding sheet by the reverse rotation of the retard roller 101.
[0058]
Thereafter, the paper feed sensor 3 is sampled at intervals of t3, and when the paper feed sensor 3 cannot detect the sheet P, the clutch 10 is turned on again. By repeating this operation until the normal timing T4 when the succeeding sheet comes to the paper feed sensor 3, the leading edge of the succeeding sheet can be held at the sensor detection position.
[0059]
With this configuration, even in a system in which the driving sources 6 cannot be stopped individually, the sheet interval can be adjusted to a desired predetermined interval.
[0060]
In such a configuration, when the forward and reverse conveying speeds of the succeeding sheet are p, and the distance L1 that the succeeding sheet is conveyed during reversal, the succeeding sheet is normal as shown in FIG. It is guaranteed that it is within the range of p * t3 + L1 before and after the newspaper. Therefore, this error can be reduced by narrowing the sampling period t3 and suppressing the stopped conveyance distance L1, so that the leading edge of the succeeding sheet P2 can be brought close to the detection position of the sheet feeding sensor 3, and the preceding sheet P1 It is possible to ensure an accurate interval.
[0061]
FIG. 9 is a flowchart showing an example of sheet interval adjustment control according to the present embodiment. The flow of control shown in the figure is the same as that described above, except that when the paper feed sensor 3 detects the leading edge of the succeeding sheet P2 in S215, the conveyance by the first conveyance roller 102 is resumed. Same as 6.
[0062]
By the way, in the first and second embodiments described above of the sheet, the reverse feeding is not completed until the leading edge of the succeeding sheet is normally conveyed, and the subsequent sheet feeding timing, or The sheet spacing may not be adjusted correctly.
[0063]
Therefore, in such a case, in the first embodiment, at least one of the sheet conveyance speed at the time of forward rotation of the first conveyance roller 2 and the sheet conveyance speed at the time of reverse rotation is made variable so The ratio of the sheet conveyance speed at the time is changed.
[0064]
For example, assuming that the length of the sheet P is PL, the conveyance speed in the forward rotation direction is p, and the scheduled sheet interval is KL, the control device 50 sets the conveyance speed during reverse rotation as P * (PL) / (KL). As a result, all the reverse feeds can be completed within the timing at which the leading edge of the succeeding sheet is normally conveyed, and the normal sheet interval can be corrected even during double feeding.
[0065]
In the second embodiment, at least one of the sheet conveying speed of the first conveying roller 102 and the reverse feeding speed of the retard roller 101 is variable, and the ratio of the sheet conveying speed and the reverse feeding speed of the retard roller 101 is changed. Like that.
[0066]
【The invention's effect】
As described above, as in the present invention, the sheet conveyed by the sheet conveying unit is detected by the sheet detecting unit, and after the detection signal for detecting the sheet is input from the sheet detecting unit, the next sheet is detected. Based on the timing at which the detection signal is input, the next sheet is reversely fed, so that proper sheet interval adjustment can be performed even when double feeding or the like occurs in the sheet.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration of a sheet feeding apparatus according to a first embodiment of the present invention.
2A is a state in which a sheet is normally conveyed, FIG. 2B is a state in which a succeeding sheet is thrust, and FIG. 2C is a state in which double feeding is occurring. FIG.
FIG. 3 is a first diagram illustrating a flow of detecting a double feed of the sheet feeding device and adjusting a desired sheet interval.
FIG. 4 is a second diagram illustrating a flow of detecting a double feed of the sheet feeding device and adjusting a desired sheet interval.
FIG. 5 is a diagram illustrating an error that occurs when adjusting the sheet interval of the sheet feeding apparatus.
FIG. 6 is a flowchart showing sheet interval adjustment control of the sheet feeding apparatus.
FIG. 7 is a diagram illustrating a configuration of a sheet feeding apparatus according to a second embodiment of the present invention.
FIG. 8 is a diagram illustrating an error that occurs when adjusting the sheet interval of the sheet feeding apparatus.
FIG. 9 is a flowchart illustrating sheet interval adjustment control of the sheet feeding apparatus.
[Explanation of symbols]
2 First transport roller 3 Paper feed sensor 7 Pickup roller 8 Cassette 50 Control device 101 Retard roller 102 First transport roller P Sheet P1 Preceding sheet P2 Subsequent sheet

Claims (11)

Sheet feeding means for feeding out the sheets stored in the sheet storage unit;
Forward and reverse reversible sheet conveying means for conveying the sheet fed by the sheet feeding means;
A sheet detecting means provided downstream of the forward / reversible sheet conveying means for detecting the sheet conveyed by the sheet conveying means;
After the detection signal for detecting the sheet is input from the sheet detection means, when the detection signal for detecting the next sheet is input earlier than a predetermined timing , the sheet conveying means capable of forward / reverse rotation is reversed. A sheet interval adjusting means that reversely feeds the next sheet and adjusts to widen the interval between the sheet and the next sheet;
A sheet feeding apparatus comprising: The sheet interval adjusting unit resumes the normal rotation of the sheet conveying unit capable of forward and reverse rotation at a timing when the sheet interval becomes a predetermined interval when the sheet detecting unit detects the leading edge of the next reversely fed sheet. The sheet feeding apparatus according to claim 1 , wherein the sheet feeding apparatus is a sheet feeding apparatus. Said sheet sensing means, the backhaul has been next sheet sheet feeding apparatus according to claim 1 or 2, characterized in that the timing of detecting to suppress a predetermined error range the tip of. At least one of a sheet conveying speed at the time of forward rotation and a sheet conveying speed at the time of reverse rotation of the sheet conveying means capable of forward / reverse rotation is variable, and the sheet interval adjusting means is configured to reverse the sheet by rotating the sheet conveying means capable of forward / reverse rotation. and when adjustment can not be the next sheet interval, according the any one of claims 1 to 3, characterized in that to vary the ratio of the sheet conveying speed of the reverse rotation and forward rotation Sheet feeding device. The sheet interval adjusting means is configured to determine the length of the sheet during the reverse rotation based on the length of the sheet in the conveyance direction, the sheet conveyance speed during normal rotation of the sheet conveyance means capable of forward and reverse rotation, and a predetermined interval between the sheet and the next sheet. The sheet feeding apparatus according to claim 4, wherein the sheet conveying speed is determined. Sheet feeding means for feeding out the sheets stored in the sheet storage unit;
A sheet conveying means for conveying the sheet fed by said sheet feeding means,
A reverse feeding means configured to rotate in a direction to return the sheet sent out by the sheet feeding means to the sheet storage unit, and to be rotated along with the rotation of the sheet conveying means;
A sheet detecting means provided downstream of the sheet conveying means for detecting the sheet conveyed by the sheet conveying means;
After the detection signal for detecting the sheet is input from the sheet detection unit, when the detection signal for detecting the next sheet is input earlier than a predetermined timing , the rotation of the sheet conveyance unit is stopped. A sheet interval adjusting means for adjusting the width of the next sheet to be increased by reversely feeding the next sheet by the reverse feeding means;
A sheet feeding apparatus comprising: 7. The sheet feeding apparatus according to claim 6, wherein the sheet interval adjusting means restarts the rotation of the sheet conveying means when the sheet detecting means detects the leading edge of the next reversely fed sheet. 8. A sheet feeding apparatus according to claim 6 , wherein the timing of detecting the leading edge of the next reversely fed sheet of the sheet detecting means is kept within a predetermined error range. At least one of the sheet conveying speed of the sheet conveying means and the reverse speed of the reverse feeding means is variable, and the sheet interval adjusting means adjusts the interval between the sheet and the next sheet by reverse feeding by the reverse feeding means. if not possible, the sheet feeding according to any one of claims 6 to 8, characterized in that to vary the backhaul speed ratio of the sheet conveying speed and said backhaul means of said sheet conveying means apparatus. The sheet interval adjusting means determines the reverse feed speed of the reverse feed means based on the length of the sheet in the conveyance direction, the sheet conveyance speed of the sheet conveyance means, and a predetermined interval between the sheet and the next sheet. The sheet feeding device according to claim 9 . An image forming unit, an image forming apparatus comprising the sheet feeding apparatus according to any one of claims 1 to 10 for feeding sheets to the image forming unit.

Images