JP2003176045A - Paper conveying device, and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve productivity by reducing paper intervals without increasing conveying speed. <P>SOLUTION: In feeding paper sheets P from any paper feeding tray 14 of a paper feeding means 11, a paper feeding operation of a paper sheet is started before the terminal end of the previous paper sheet goes out of a paper feeding roller 16, thereby feeding the paper sheets in a continuous state having no paper interval. A conveying clutch is turned off before the terminal end of the previous paper sheet goes out of a resist sensor 21, thereby forming an interval between the adjacent paper sheets. A predetermined interval is formed and then the conveying clutch is turned on. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet conveying device for feeding sheets one by one, a copying machine having the sheet conveying device,
The present invention relates to an image forming apparatus such as a printer, a facsimile, and a printing machine.

[0002]

2. Description of the Related Art As shown in FIG. 5, for example, a sheet conveying apparatus of this type supplies a sheet feeding means 11 for feeding the stacked sheets one by one in order from the top sheet, and a sheet feeding means 11 for feeding the sheets. Conveying means 12 for conveying the printed paper, and the conveying means 12
A registration roller pair 13 is provided on the downstream side of the sheet conveyance direction as a registration unit that conveys the sheet to the image transfer portion at a predetermined timing. The sheet P is temporarily stopped by the pair of registration rollers 13, the skew displacement is corrected, and then the sheet P is sent to the image transfer portion at a predetermined timing. Paper feeding means 1
1 is a paper feed tray 14a, 14b, 1 provided in three stages
4c, and these paper feed trays are provided with feed rollers 15a, 15b, 15c and a paper feed roller 16 respectively.
a, 16b, 16c, separation rollers 17a, 17b, 17
c is provided correspondingly. The feed roller 15 and the paper feed roller 16 are synchronously driven, and the driving is turned on / off by a paper feed clutch (not shown).

The transport means 12 is a transport path 1 extending substantially vertically.
8, and a pair of conveying rollers 19a, 19b, 19c are provided in the conveying path 18 corresponding to each sheet feeding tray 14. The interval between each pair of transport rollers 19a, 19b, 19c is set to be equal to or less than the feed length of the minimum cut sheet. Transport sensors 20a, 20b, and 20c are provided near the downstream side of each transport roller pair 19 in the sheet transport direction as transport unit sheet detection means for detecting the leading edge and the trailing edge of the sheet P. These transport sensors 20a, 20b, 20c
Is provided to monitor the size of the sheet P being conveyed and the state of conveyance, and it is also possible to confirm the sheet position when a jam occurs. In front of the registration roller pair 13 (in the vicinity of the upstream side in the paper transport direction), a registration sensor 21 as a pre-registration paper detection unit that detects the leading edge and the trailing edge of the paper P is provided. The paper feeding means 11 and the transport means 12 are driven by a drive motor (not shown), and these drives are collectively turned on / off by a transport clutch (not shown).

The feeding roller 15 is retracted upward by spring pressure, and is lowered by a suction (ON) operation of a solenoid (not shown) to come into contact with the uppermost surface of the paper P. Immediately after the solenoid operates, an operation signal is input to the paper feed clutch.
Generally, the operation time of the solenoid is 100 msec from the input signal until it is completely operated, and it is 10 to 50 msec until the transport clutch and the sheet feeding clutch are completely connected from the input signal. The transport clutch and the paper feed clutch are connected to each other, and the rotation of the drive motor is driven by the paper feed roller 1.
6 and the delivery roller 15, the delivery roller 1
The uppermost sheet P1 that has abutted against the sheet 5 is sent to the sheet feeding roller 16. At that time, the lower sheet P2 of the uppermost sheet P1 is dragged by the uppermost sheet P1 and the sheet feeding roller 16
Often sent to. When not fed, the lower sheet P2 does not move 1 mm from the original position. The uppermost sheet P1 sent to the sheet feeding roller 16 by the delivery roller 15 and the lower sheet P2 are separated by the separation roller 17, and only the uppermost sheet P1 is the downstream transport roller pair 1.
Sent to 9. The lower sheet P2 is stopped in the sheet feeding unit 11 so that it is not conveyed downstream by the separation roller 17.
That is, the separation method of the paper feeding in the paper feeding means 11 is FRR.
(Return) Separation method.

The sheet feeding / transporting operation after the transporting means 12 will be described below by taking the sheet feeding from the lowermost sheet feeding tray 14c as an example. The sheet P1 sent from the paper feed roller 16 is sent to the pair of transport rollers 19c, and the leading edge is detected by the transport sensor 20c immediately after the pair of transport rollers 19c. When the feeding is further continued, the rear end is also detected by the transport sensor 20c. The size of the sheet P1 can be grasped by detecting the leading edge and the trailing edge by the transport sensor 20c, and the sheet size accommodated in the sheet feed tray 14c and the input sheet size can be checked.

Therefore, if the paper size that is actually accommodated is different from the input paper size, the operation of the apparatus is immediately stopped and an erroneous set is displayed, thereby making a wasteful copy. You don't have to. Conveyor roller pair 1
The paper P1 sent to 9c is further fed with a pair of transport rollers 19b,
The registration roller pair 13 is reached via 19c. At this time, the registration roller pair 13 is not driven,
It has stopped. When the leading edge of the sheet P1 is detected by the registration sensor 21 immediately before the registration roller pair 13, the control unit (not shown) calculates the timing at which the leading edge abuts the nip of the registration roller pair 13 and a bend of several millimeters is formed. , Disconnect the transport clutch. By disconnecting the transport clutch, the feed roller 15, the paper feed roller 16, and the transport roller pairs 19a, 19b, and 19c are stopped, and the registration standby state is entered.

The time required from the start of feeding to the waiting for registration up to this point is as follows: (1) The uppermost sheet P1 of the sheet feed tray 14 is at a predetermined position or is brought along with the preceding sheet and the sheet feed roller 16
Has been sent to the site? (2) Whether the paper feed clutch is immediately engaged or delayed. (3) Are the outer diameters of the feed roller 15, the paper feed roller 16, and the conveying roller pairs 19 delicately large or small due to deterioration? (4) Is the coefficient of friction of the feed roller 15, the paper feed roller 16, and the pair of transport rollers 19 high or is it deteriorated due to deterioration? (5) Is the rotation speed of the drive motor fast or slow? Etc., a difference occurs, and in (1), a difference of 30 mm is usually
A difference of about 40 msec in (2), a difference of about 5% in (3), a difference of up to 15% in (4), and a maximum of 2 in (5).
% Difference occurs, and in general, when delivered the fastest,
When it is placed the latest, there is a time lag corresponding to 60 mm conveyance. Since the paper P sent from the paper feed tray 14c must match the timing of the image formed by the image transfer unit, the image formation start timing is set when the paper P is most delayed, and the paper P is conveyed quickly. When this is done, the resist waiting time is made longer.

The feeding start timing of the second sheet P2 is 2 times as long as the trailing edge of the first sheet P1 and never catches up even if the first sheet P1 is delayed and the second sheet P2 is accelerated. A space is formed at the leading edge of the second sheet P2. Therefore, contrary to the above, when the first sheet P1 is fast and the second sheet P2 is slow, the distance between the trailing edge of the first sheet P1 and the leading edge of the second sheet P2. Grows. In general, 1 even when the space between sheets is smallest
Since 5 mm is ensured, it means that 75 mm is opened when the maximum interval is opened at that timing. Further, about 5 mm is added as a waiting time for the registration roller pair 13 to send the image-formed image at a timing, so that the sheet interval after the registration roller pair 13 is about 80 mm or more. That is, even if there is a sheet interval of 15 mm in front of the registration roller pair 13, if the sheet delays to the maximum, it is 80
Since the difference is 65 mm, the difference of 65 mm is the amount of waiting and stopping for a long time as the resist waiting time. The sheet feeding timing for the third and subsequent sheets is the same as the timing for the second sheet.

FIG. 6 is a time-series flow chart of conventional paper conveyance. When the leading edge of the first sheet is detected by the transport sensor 20c, the sheet feeding clutch is turned on, but the sheet feeding clutch is delayed in connection (d). x is the tip detection, y
Indicates the trailing edge detection. The first and second sheets are sent out from the paper feed tray 14c, but the third sheet is brought to the position of the paper feed roller 16 along with the second sheet, and the third sheet is sent out from here, so the distance from the second sheet Is short and the waiting time is short. The ON interval of the registration roller pair 13 (ON interval of the registration clutch) is constant for all the sheets P. FIG. 7 is a timing chart of a conventional operation. The arrows in the figure show the relationship of the reference positions of control. When the leading edge of the previous sheet is detected by the conveyance sensor 20c, the solenoid is turned on after t time to start the next sheet (). That is, it is the front end rear end reference paper feed method. When waiting for registration, the waiting time is added to the time t (). Paper feed roller 1
Since it has moved forward to 6, the conveyance sensor 20c detects it immediately after the operation of the paper feed clutch (). Similarly to the third sheet, the fourth sheet was also moved forward to the sheet feeding roller 16 along with the third sheet. Therefore, the conveyance sensor 20c immediately after the operation of the sheet feeding clutch.
Detected by (). The idling of the transport clutch indicates a standby in front of the registration roller pair 13, and there are variations in time. If it is sent to the registration roller pair 13 quickly, the waiting time becomes long ().

[0010]

In order to increase the amount and number of copied sheets produced in the image forming apparatus, that is, to improve productivity, the operating speed in the apparatus is increased, or the sheet-to-sheet type is increased. Therefore, it is necessary to take measures such as shortening the interval of 2 as much as possible to reduce the time of non-image formation. When the operating speed in the equipment is increased, the parts that compose the equipment are consumed faster, the life of the equipment is shortened, the maintenance cycle is shortened, or the operating noise of the equipment is increased and the noise becomes loud. Or Costs are required for these measures, and eventually the device cost is increased. In order to shorten the sheet interval, it is necessary to strictly control the feeding control of each sheet, but the time required for one sheet to reach the image transfer section from the paper feed tray depends on the paper type, the paper thickness, the roller Due to changes over time and the performance of individual electrical parts, the transport conditions for each sheet are not stable, so that the time from the paper feed tray to the image transfer unit varies. In the conventional transport control method, the variation is taken into consideration, and the sheet interval is set in accordance with the maximum delay time, so that it is possible to reduce the interval until no problem occurs.

Therefore, it is an object of the present invention to provide a sheet conveying apparatus which can increase the productivity by reducing the sheet interval without increasing the conveying speed, and an image forming apparatus having the sheet conveying apparatus.

[0012]

In view of the fact that a complicated control cannot be avoided due to the existence of a paper interval, the present invention intentionally reduces the load on the transport control without providing the paper interval, and the necessary control is required. It was decided to provide a paper interval only at the location. Specifically, according to the first aspect of the invention, a sheet feeding unit that separates and feeds the sheets stacked and accommodated in the sheet feeding tray one by one from the uppermost sheet, and the sheet feeding unit feeds the sheets. And a registration unit that is provided on the downstream side of the conveyance unit in the sheet conveyance direction to convey the sheet to an image transfer portion at a predetermined timing, and a paper feed that turns on / off the driving of the paper feed unit. A clutch, a conveyance clutch for turning on / off the driving of the conveyance means, a conveyance section paper detection means for detecting the paper fed by the paper feeding means, and a paper provided near the upstream of the registration means. In a paper conveyance device having a pre-registration paper detection means, a conveyance section paper detection means, and a control means for managing the position of the paper based on the detection information of the pre-registration paper detection means, in the continuous paper feeding, the paper feeding means From above After feeding the paper to the feeding means, the paper feeding clutch is turned off, and the trailing end of the paper being fed is fed out of the paper feeding means by the control means based on the detection signal from the paper detecting means of the transport section. The configuration is such that the time just before reaching the position is calculated, the paper feed clutch is turned on at the calculated timing, and paper is fed in the continuous feed state.

According to a second aspect of the present invention, in the sheet conveying apparatus according to the first aspect, the rear end of the first sheet is set to the delivery position when the first sheet is continuously fed. Even if it reaches, the paper feed clutch is not turned on, and after a lapse of a predetermined time, the paper feed clutch is turned on to provide a predetermined space between the first sheet and the second sheet, and the second sheet and thereafter. The paper is fed in a continuous feed state.

According to the invention of claim 3, claim 1 or 2
In the paper transporting apparatus described above, the control means calculates the timing before the trailing edge of the second and subsequent sheets of paper passes through the most downstream part of the transporting means and reaches the pre-registration sheet detecting means. At this timing, the transport clutch is temporarily turned off, and the transport clutch is turned on after the opening from the leading edge of the next sheet reaches a predetermined amount.

According to a fourth aspect of the present invention, in the sheet conveying apparatus according to the third aspect, a conveying section downstream sheet detecting means for detecting a sheet is provided in the vicinity of the most downstream portion of the conveying means, and the conveying section downstream sheet is provided. Based on the detection information of the detection means, the control means calculates the distance between the second and subsequent sheets,
A configuration is adopted in which the time for temporarily stopping the transport clutch is shortened by the already formed sheet interval.

According to the invention of claim 5, claim 3 or 4
In the above-described sheet conveying device, the predetermined amount of opening is set to a size such that the pre-registration sheet detecting unit can detect the sheet interval.

According to a sixth aspect of the present invention, in the image forming apparatus for feeding the sheets one by one by the sheet conveying device and transferring the image to the fed sheets, the sheet conveying device comprises:
The configuration is as described in any one of claims 1 to 5.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to FIG.
It will be described with reference to FIG. Note that the same parts as those of the conventional example are denoted by the same reference numerals, and the description of the already-explained configuration and function is omitted unless particularly necessary. First, a schematic configuration of a copying machine 1 as an image forming apparatus according to this embodiment will be described with reference to FIG. The copying machine 1 has an image forming unit centered on the photosensitive drum 2 as an image carrier, in addition to the above-described components. Around the photosensitive drum 2, a charging unit 3 and a writing unit 4 are arranged in the order of the rotation directions indicated by arrows.
Developing means 5, transfer means 6, and cleaning means 7
Etc. are arranged. Between the charging unit 3 and the developing unit 5, the exposure unit on the photosensitive drum 2 is irradiated with the exposure light from the writing unit 4 and scanned.

The image forming operation in the copying machine 1 is performed in the same manner as the conventional one. That is, when the photoconductor drum 2 starts to rotate, the surface of the photoconductor drum 2 is uniformly charged by the charging means 3, and the exposure light is irradiated and examined on the exposure portion based on the image information from the reading means (not shown). An electrostatic latent image corresponding to the image to be created is formed. This electrostatic latent image is moved to the developing means 5 by the rotation of the photosensitive drum 2, and the toner is supplied there to be visualized, and a toner image is formed. The toner image formed on the photosensitive drum 2 is transferred onto the paper P entering the image transfer portion at a predetermined timing by applying a transfer bias by the transfer unit 6.

The sheet P carrying the toner image is conveyed toward the fixing means 9 by the belt conveying means 8 and fixed by heat and pressure by the fixing means 9, and then is ejected to a paper ejection tray (not shown) by the paper ejection roller pair 10. Ejected and stacked. The residual toner remaining on the photosensitive drum 2 without being transferred by the image transfer portion reaches the cleaning means 7 as the photosensitive drum 2 rotates, and is scraped off by the cleaning blade while passing through the cleaning means 7. Be cleaned. After that, the residual potential on the photoconductor drum 2 is removed by a discharging unit (not shown), and the apparatus is prepared for the next image forming step.

Next, the drive structure of the sheet feeding means 11 and the conveying means 12 will be described with reference to FIG. As a whole, the driving force of the drive motor 22 is transmitted via the timing belt 27 to the conveying roller pairs 19 a, 19 b, 19 c, and the paper feeding roller 16.
a, 16b, 16c. A gear 23 is attached to the output shaft of the drive motor 22, and a gear clutch 24 meshing with the gear 23 is connected to a transport clutch 25. A gear 26 is attached to the shaft of the gear 24, and the timing belt 27 is driven by the gear 26. A gear 28c that meshes with the timing belt 27 is provided, a gear 29c meshes with the gear 28c, and a gear 31c meshes with the gear 29c. Gear 2
A sheet feeding clutch 30c is provided at 9c. Gear 2
A gear 35c and a paper feed roller 16c are attached to the shaft of 9c. A gear 36c meshes with the gear 35c, and a gear 37c mounted on the shaft of the feed roller 15c meshes with the gear 36c. With this configuration,
The feed roller 15c and the paper feed roller 16c rotate synchronously.

A gear 32c meshes with the shaft of the gear 31c, and a gear 33c attached to the shaft of the separation roller 17c meshes with the gear 32c. A torque limiter 34c is provided on the shaft of the separation roller 17c. Therefore, the paper feeding method of the paper feeding means 11 in the present embodiment is such that the feeding roller 15c, the paper feeding roller 16c,
This is an FRR paper feeding system using a combination of a separation roller 17c and a torque limiter 34c whose rotation direction can be switched. The separation method is not particularly limited as long as it is a friction separation method using the paper feed roller 16 and a roller or a separation member of the separation pad. Although the drive structure corresponding to the lower paper feed tray 14c has been described, the same applies to the middle and upper tiers only with the addition of the Latin letters added. Although not shown, the pair of conveying rollers 19a, 19b, 19c are also driven by the driving force of the drive motor 22, and the operation of the conveying clutch 25 arranged immediately after the drive motor 22 causes the feeding roller 15, the sheet feeding roller 16, the conveying roller. The pairs 19a, 19b, 19c are collectively turned on / off.

The drive motor 22 sends out a roller 15,
Paper feed roller 16, separation roller 17, transport roller pair 19
After distributing the driving force to a, 19b, and 19c, a clutch is arranged to control the driving of each roller by a plurality of clutches, or a driving source such as a stepping motor is directly connected to each roller to turn on the driving source. The rotation may be controlled by the off operation. In the present embodiment, as described above, the configuration is such that one transport clutch 25 is used to turn on / off at once, so that the cost can be kept low and the power consumption can be reduced compared to the case where many expensive clutches are used. have. The registration roller pair 13 is
A driving force is transmitted from a driving source (not shown) via a registration clutch (not shown). It may be driven directly by the drive source without using the registration clutch.

Next, the sheet feeding / conveying operation and its timing in this embodiment will be described with reference to FIGS. 3 and 4.
Note that, as in the conventional case, the case of feeding from the lowermost sheet feed tray 14c will be described. The operation / timing of feeding the first sheet P1 and the second sheet P2 is the same as the conventional one. Therefore, the leading edge and the trailing edge of the sheet can be detected by the transport sensor 20c immediately after the sheet feeding, and it is possible to prevent wasteful copying by stopping the apparatus when the actual sheet size is different from the input size. Third sheet P3
As for the delivery timing, the delivery operation is started from the state where the trailing edge of the second sheet P2 remains on the side of the sheet feeding tray 14c by about 50 mm before the trailing edge of the second sheet P2 comes out of the feeding roller 16c (in FIG. 4). The breakdown of 50 mm is a numerical value in which the time required until the solenoid completes the suction operation and the paper feed clutch 30c is engaged is multiplied by the transport speed to allow for a margin. In other words, after the sheet P2 is fed from the sheet feeding unit 11 to the transporting unit 12, the sheet feeding clutch 10c is turned off, and the leading end from the transport sensor 20c is controlled by the control unit (not shown) (which can also serve as the main controller of the copying machine). Based on the detection signal, the trailing edge of the sheet P2 being fed is the feeding position of the feeding means 11 (position of the feeding roller 15).
Is calculated, and the paper feed clutch 10c is turned on at the calculated timing to feed paper in the continuous feed state. As described above, when the trailing edge of the second sheet P2 comes out of the sheet feeding tray 14c and comes out of the sheet feeding roller 16c, the leading edge of the third sheet P3 immediately follows.

When the third sheet P3 is fed, the second sheet P is fed.
The third sheet P3 even if it starts before the feeding of the second sheet is completed
The leading edge of the second sheet P2 is not conveyed to the sheet feeding roller 16c by being prevented from being conveyed by the separation roller 17c.
The trailing edge is not conveyed until immediately after the trailing edge of the trailing edge of the trailing edge of the sheet feeding roller 16c. By feeding the fourth sheet P4 and subsequent sheets in the same manner as the third sheet P3, as shown in the time-series flow chart of the sheet conveyance in FIG. 3, the fourth sheet P3 is placed at the rear end of the fourth sheet P3. The leading edge of the sheet P4 continues and the fourth sheet P4
A so-called continuous feed state in which the leading edge of the fifth sheet of paper P continues to the trailing edge is possible. 1 by registration roller pair 13
The second sheet of paper P1 is sent, and the registration roller pair 13 is in the middle of transporting the second sheet of paper P2, and the trailing edge of the second sheet of paper P2 has passed the downstreammost transport roller pair 19a and past the transport sensor 20a. By the way, the transport clutch 25 is temporarily turned off. As a result, the second sheet of paper P2 being conveyed by the registration roller pair 13 continues to be conveyed as it is, but the conveyance of the third and subsequent sheets of paper P3 is stopped by the conveyance clutch 25 being turned off. Be stopped. As a result, a gap is formed between the trailing edge of the second sheet P2 and the leading edge of the third sheet P3 fed in the continuous feeding state.

The trailing edge of the second sheet P2 and the third sheet P
When a certain amount of space is opened between the leading end of No. 3 and the leading end of No. 3, the transport clutch 25 is engaged (turned on). As a result, the registration roller pair 13 after the registration sensor 21 can be kept open. The timing for stopping the transport clutch 25 is determined by the control means based on the length of the sheet P being transported and the start of driving the registration roller pair 13. Similarly, the timing at which the transport clutch 25 is re-engaged is determined from the registration start timing of the second sheet P2, which is the front sheet. The sheet interval created in front of the registration roller pair 13 is safe even if the trailing edge of the sheet is completely removed from the registration roller pair 13 and the registration clutch (not shown) is stopped, and about 10 mm at which the registration sensor 21 can detect the sheet interval. Good. If the timing of disengaging the registration clutch is too early, when a control problem occurs, the trailing edge of the front sheet that is being conveyed is disengaged before the end of the registration roller pair 13, and the image being transferred is disturbed.
Further, the registration sensor 21 fails to detect the sheet interval, and it is recognized that the sheet is not open in the control although the interval of 3.4 mm is actually provided between the rear edge of the front sheet and the front edge of the rear sheet. Since there are many cases, 10 mm as described above
It is good for obtaining stable transport quality.

It is sufficient that the sheet groups P2, P3, P4 and P5 sent from the sheet feeding means 11 in a continuous feeding state are spaced apart in front of the conveying roller pair 19a before the registration roller pair 13. is expected. When the transport linear velocity of the downstream transport roller pair 19a near the registration roller pair 13 is slightly higher than the transport linear velocity of the upstream transport roller pair 19c near the paper feed tray 14c, the downstream transport roller pair 19 is slightly faster.
At the beginning, the delicate interval gradually widens as the paper P conveyed by a is fed. Therefore, the amount of spread (interval amount) between the sheets is determined by the conveyance sensor 20a arranged immediately after the conveyance roller pair 19a closest to the registration roller pair 13.
To detect. In this case, the transport sensor 20a functions as a transport unit downstream sheet detection unit. After that, the above interval amount is subtracted from the stop time from when the transport clutch 25 is stopped to when the transport clutch 25 is re-engaged so that it becomes the same as the interval (10 mm) at the time of stop / redrive after the continuous feed state is maintained. To control. That is, the re-engagement of the transport clutch 25 is advanced by the distance between the sheets. As shown in FIG. 4, when the paper interval is not detected by the carry sensor 20a, the carry clutch 25 is disengaged for a predetermined time (t seconds) to obtain the space of 10 mm. The paper interval is t1 by the conveyance sensor 20a.
Alternatively, when detecting for t1 ′, the transport clutch 25 is disengaged for t2 or t2 ′ (t1 + t2ort1 ′ + t2 ′ = t).

For example, when the conveyance sensor 20a determines that the distance between the trailing edge of the second sheet P2 and the leading edge of the third sheet P3 is 4 mm, the stop time of the third sheet P3 is set to 6 mm. By doing so, the actual paper interval when the transport clutch 25 is re-engaged becomes 10 mm. By controlling the sheet interval before the second registration roller pair 13 to be 10 mm, the sheet interval after the registration roller pair 13 is 15 m.
The more the number of continuous copies is reduced to about m, the higher the productivity becomes. Even if the A4 size paper is horizontally fed, the paper interval is 100 mm, even if the conveyance speed is the same, compared to the conventional 80 mm. However, 100% more than before
-{(Paper length + 15mm) / (paper length + 80mm)}
= 22.4% of the time, copying was completed earlier than the time taken by the conventional method, {(paper length + 80 mm) /
(Paper length +15 mm)}-100% = 28.9 More copies can be made.

[0029]

According to the invention described in claim 1 or 6, the sheets stacked and accommodated in the sheet feeding tray are arranged in order from the top sheet.
A sheet feeding unit that separates and feeds the sheets one by one, a conveying unit that conveys the sheet fed from the sheet feeding unit, and an image transfer at a predetermined timing provided on the downstream side of the conveying unit in the sheet conveying direction. Detecting the sheet fed by the sheet feeding means, the sheet feeding clutch for turning on / off the driving of the sheet feeding means, the feeding clutch for turning the driving of the sheet feeding means on / off, Transport section paper detection means, pre-registration paper detection means provided near the upstream of the registration means for detecting paper, and paper position based on the detection information of the conveyance section paper detection means and pre-registration paper detection means In a paper transporting apparatus having a control means for managing the above, during continuous paper feeding, after feeding the paper from the paper feeding means to the transporting means, the paper feed clutch is turned off, and the control means controls the paper feeding section of the transporting section. The time when the trailing edge of the sheet being fed reaches the delivery position of the sheet feeding means is calculated based on the detection signal from the sheet feeding means, and the sheet feeding clutch is turned on at the calculated timing to continuously feed the sheet. Since it is decided to feed the paper, the paper feeding operation is not started by aiming at the leading edge of the next paper but by the trailing edge of the front paper being conveyed. The productivity can be improved without shortening the machine life and maintenance intervals, and without increasing noise and cost. In addition, since the paper interval is not provided, it is possible to reduce the burden on the transport control.

According to the invention described in claim 2 or 6, in the paper conveying apparatus according to claim 1, when the first sheet of continuous paper is fed, the trailing edge of the first sheet is Even when the paper feed position is reached, the paper feed clutch is not turned on and the paper feed clutch is turned on after a lapse of a predetermined time so that the first sheet of paper
Since a predetermined interval is provided between the first and second sheets, the second and subsequent sheets are fed in a continuous feed state, so that even if wrong size sheets are erroneously set, this can be detected, and wasteful copying can be performed. It can be prevented from being done.

According to the invention of claim 3 or 6, in the paper transporting device of claim 1 or 2, the trailing edge of the second and subsequent sheets of paper passes through the most downstream portion of the transporting means before the registration. The timing before reaching the sheet detecting means is calculated by the control means, the conveying clutch is temporarily turned off at the calculated timing, and the conveying clutch is opened after the opening with the leading edge of the next sheet reaches a predetermined amount. Since it is turned on, it is possible to reduce the processing amount related to the conveyance control, and it is possible to prevent a problem caused by a delay in the control processing that suddenly occurs when the processing amount increases.

According to the invention of claim 4 or 6, in the paper transporting device of claim 3, a transporting section downstream sheet detecting means for detecting a sheet is provided in the vicinity of the most downstream portion of the transporting means. The interval between the second and subsequent sheets is calculated by the control unit based on the detection information from the sheet downstream sheet detecting unit, and the time for temporarily stopping the conveying clutch is shortened by the already formed sheet interval. Therefore, it is possible to make the sheet interval after the registration means constant and always improve the productivity.

According to the fifth or sixth aspect of the invention, in the sheet conveying apparatus according to the third or fourth aspect, the predetermined amount of opening is set to a size such that the pre-registration sheet detecting means can detect the sheet interval. Since it is determined that the image is transferred, it is possible to prevent the image being transferred from being disturbed.

[Brief description of drawings]

FIG. 1 is a schematic front view of a copying machine as an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic perspective view of a drive configuration of a sheet feeding unit.

FIG. 3 is a time-series flow chart of sheet conveyance.

FIG. 4 is a timing chart of the operation.

FIG. 5 is a schematic front view of a sheet feeding / conveying configuration in a conventional example.

FIG. 6 is a time-series flow chart in sheet conveyance of a conventional example.

FIG. 7 is a timing chart of the operation of the conventional example.

[Explanation of symbols]

2 Photoconductor drum as latent image carrier 10 Paper feed clutch 11 Paper feeding means 12 Transport means 14 Paper tray 20 Conveyance sensor as conveyance unit paper detection means 20a Conveying unit downstream paper detection means 21 Registration sensor as pre-registration paper detection means 25 Transport clutch P paper

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masataka Shimosako             1-3-3 Nakamagome, Ota-ku, Tokyo, stock             Company Ricoh (72) Inventor Nobutaka Suzuki             1-3-3 Nakamagome, Ota-ku, Tokyo, stock             Company Ricoh (72) Inventor Yasuhiro Kodaira             1-3-3 Nakamagome, Ota-ku, Tokyo, stock             Company Ricoh (72) Inventor Hajime Ota             1-3-3 Nakamagome, Ota-ku, Tokyo, stock             Company Ricoh F-term (reference) 2H072 AA07 AA16 AA24 AB06 BA03                       CA01 JA02 JA08                 3F048 AA02 AA04 AA05 AB01 BA05                       BB02 CA04 CC03 DA06 DB07                       DC00 EB30                 3F049 DA12 EA01 EA23 EA27 LA02                       LA05 LA07 LB03                 3F343 FA02 FB02 FB03 FB04 FC03                       FC14 GA01 GB01 GC01 GD01                       HA36 JA01 LB08 LC03 LC05                       LD30 MA16 MA45 MB14 MB15                       MC06 MC08

Claims (6)

[Claims] 1. A paper feed means for separating and feeding the papers stacked and accommodated in a paper feed tray one by one from the top, and a carrying means for carrying the papers fed from the paper feed means. A registration unit that is provided on the downstream side of the conveyance unit in the sheet conveyance direction and conveys the sheet to an image transfer portion at a predetermined timing;
A paper feed clutch for turning on / off the drive of the paper feed means, a transport clutch for turning on / off the drive of the transport means, and a transport unit paper detection means for detecting the paper fed by the paper feed means, A sheet having a pre-registration sheet detection unit provided near the upstream of the registration unit for detecting a sheet, a conveyance unit sheet detection unit, and a control unit for managing the position of the sheet based on the detection information of the pre-registration sheet detection unit. In the carrying device, during continuous paper feeding, after the paper is fed from the paper feeding means to the carrying means, the paper feeding clutch is turned off, and the control means performs the feeding operation based on the detection signal from the paper feeding section detecting means. It is characterized in that the time just before the trailing edge of the paper being fed reaches the delivery position of the paper feed means is calculated, the paper feed clutch is turned on at the calculated timing, and paper is fed in the continuous feed state. Paper transport Sending device. 2. The sheet conveying apparatus according to claim 1, wherein when the first sheet of the continuous sheet is fed, the sheet is fed even if the trailing edge of the first sheet reaches the delivery position. The paper feed clutch is turned on after a lapse of a predetermined time without turning on the paper clutch to provide a predetermined space between the first sheet and the second sheet,
A sheet conveying device characterized in that the second sheet and subsequent sheets are continuously fed. 3. The sheet conveying apparatus according to claim 1, wherein the timing before the trailing edge of the second and subsequent sheets of paper passes the most downstream portion of the conveying means and reaches the pre-registration sheet detecting means. A sheet conveying apparatus, which is calculated by the control means, temporarily turns off the conveying clutch at the calculated timing, and turns on the conveying clutch after a predetermined amount of opening from the leading edge of the next sheet is reached. . 4. The sheet conveying apparatus according to claim 3, further comprising a conveying section downstream sheet detecting means for detecting a sheet in the vicinity of the most downstream portion of the conveying section, and detecting information of the conveying section downstream sheet detecting means. Based on the above, the control means calculates an interval between the second and subsequent sheets, and shortens the time for temporarily stopping the conveying clutch by the already formed sheet interval. 5. The sheet conveying apparatus according to claim 3 or 4, wherein the predetermined amount of opening is set to a size such that the pre-registration sheet detecting means can detect the sheet interval. apparatus. 6. An image forming apparatus that feeds sheets one by one by a sheet conveying device and transfers an image to the fed sheets, wherein the sheet conveying device is one of claims 1 to 5. An image forming apparatus, characterized in that