JPH0629097B2 - Paper feeder - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding device in a copying machine, a printing machine or the like, and more particularly to a drive control mechanism for a relay roller provided at an intermediate position according to the length of a conveyance path.

2. Description of the Related Art When the length of the conveyance path from the paper feed section to the registration rollers is long, it is common practice to provide a relay roller on the way.

In this case, the paper is fed one by one from the paper feed unit by the paper feed roller, the leading edge of the paper is gripped by the relay roller, and the relay roller conveys the paper to the nip portion of the registration roller, and bends to stop the drive. To do.

Conventionally, even when the registration roller is driven in synchronization with the image on the photoconductor, the relay roller stops driving, and the trailing edge of the paper is conveyed while slipping on the relay roller. . Therefore, the driving load of the registration rollers becomes large, which hinders the stabilization of roller conveyance. In addition, no consideration was given to the image forming system process speed when driving the relay roller.

OBJECT The present invention is intended to provide a sheet feeding device that can eliminate the above-mentioned drawbacks of the conventional example and stabilize the roller conveyance.

Structure For this purpose, the present invention is provided with a relay roller having a drive system for feeding the paper at substantially the same speed as the paper feed section and a drive system for feeding the paper at the same speed as the image forming process speed. Is.

Next, the present invention will be described based on an example.

FIG. 1 is a schematic configuration diagram of a paper feeding unit, which is 1, 2, 3, 4
Is a paper feed unit arranged vertically, and 5, 6, 7, and 8 are paper feed rollers. The paper feed rollers 5, 6, 7 and 8 feed the paper one by one from the top of each paper bundle 9.

Further, the buffers 13 and 14 as the bending portion of the paper are formed by the guide plates indicated by 10, 11, 12 and 15, 20, 21, respectively. The relay roller 16 is located between the registration roller 18 and the paper feed roller 7, and the relay roller 17 is similarly located between the relay roller 16 and the paper feed roller 8. Paper size detection is performed in each paper feed unit (not shown). A paper detection sensor 19 is installed near the upstream side of the registration roller 18.

Next, the operation will be described according to the flow of paper.

In the paper feeding unit 1, one paper is fed by the paper feeding roller 5. When the leading edge of the paper is detected by the paper detection sensor 19, it is driven for a certain period of time (by a pulse signal or the like), and the driving of the paper feed roller 5 is stopped. At this time, the registration roller 18 is stopped, the leading edge of the paper hits the nip of the registration roller 18, and a predetermined amount of deflection is formed in the buffer 13 to correct the paper such as skew, and the leading end of the paper is placed in the nip of the roller. Hold it completely to improve the transportability of the registration rollers.

Next, the registration roller 18 is driven in synchronization with the image forming system, and sends the paper to the image forming system so that the image is placed at a predetermined position. The paper feeding unit 2 is similar to the paper feeding unit 1. In the paper feeding unit 3, the paper feeding roller 7 and the relay roller 16 are driven by the paper feeding command, the paper is fed until it is bent as described above, and the driving is temporarily stopped.

Next, while the registration roller 18 feeds the paper, the relay roller 16 is rotated at a constant speed for each paper size by a separate drive for a fixed time for each paper size so that the deflection of the paper formed in the buffer 13 is not eliminated. . In the paper feeding unit 4, the paper feeding roller 8 and the relay rollers 17 and 16 are sequentially driven, and as described above,
A buffer is made in the buffer 13 and the paper is temporarily stopped. At this time, similarly in the paper feeding unit 4, the paper feeding rollers 7 and 8 have a time (including a time delay such as a slip) that the leading edge of the paper reaches the nearest downstream relay rollers 16 and 17. Stop the driving of the paper feed rollers 7 and 8 (to prevent the next paper from being continuously fed out if it is a small size paper). Next, while the registration roller 18 feeds the paper, the relay rollers 16 and 17 are moved to the registration roller 18 depending on the paper size.
Rotate at a constant speed so that an appropriate amount of deflection is formed in the buffer 13.

In this way, it is possible to prevent the load on the registration rollers 18 from largely changing depending on the conveyance path, and to equalize the registration roller driving load for each sheet feeding unit. As a result, the transportability of the registration roller 18 is stabilized (slip is constant), and the vertical magnifications of the respective sheet feeding units are averaged.

Even if the path between the paper feed roller and the registration roller is long, by increasing the linear speed of the paper feed roller and the relay roller, the same first copy time as that of the paper feed unit with a short path can be realized.

2, 3, and 4 show a paper feed unit 1 (2), a paper feed unit 3,
FIG. 6 is a diagram showing a state of feeding paper from a paper feeding unit 4 (a).
The flexure is provided, and (b) shows the driving state of the registration roller. Further, FIG. 5 is a timing chart in the sheet feeding section 4.

Next, the drive system of the relay rollers 16 and 17 will be described with reference to FIG.

Electromagnetic clutches 22, 23 and 24 having gears are mounted on the registration roller 18 and the relay rollers 16 and 17, respectively. Each clutch is connected to a main body drive system (not shown), and the registration roller 18 conveys the paper at the same speed as the speed of the image forming system process. Further, the relay rollers 16 and 17 convey the paper at the same speed as the paper feeding mechanism (paper feeding roller). When the registration roller 18 rotates, the electromagnetic clutch 22 is turned on,
The gear 22a rotates in the direction of the arrow. At this time, the relay roller 1
Gears 26 and 2 with one-way clutches built in 6 and 17
8 receives the drive of the gear 22a by the idle gears 25 and 27, and the relay rollers 16 and 17 are respectively the registration rollers 1
Rotate in the direction of the arrow at the same speed as 8.

FIG. 7 is a schematic diagram of the one-way clutch of the gears 26 and 28. As can be seen from this figure, when the electromagnetic clutch 23 or 24 is turned on, the shaft rotates in the direction of the dotted arrow, and the relay roller rotates. At this time, since the one-way clutch 29 is in the disengagement direction, the gear 26 or 28 is not driven and the registration roller 18 can maintain the standby state. Next, when the registration roller 18 starts to rotate by the electromagnetic clutch 22, the relay rollers 16 and 17 pass through their respective gears,
The gears 26 and 28 rotate in the direction of the solid line arrow in FIG. 7, the one-way clutch locks with the shaft, and the relay rollers 16 and 17 rotate. At this time, since the electromagnetic clutches 23 and 24 are in the off state, the relay rollers 16 and 17 carry the paper at the same speed as the registration rollers, that is, at the same speed as the image forming system process speed.

There are various driving methods. In the embodiment, the registration roller is driven, but the main body may be driven.
The relay roller may be driven by another motor.

Effect As described above, the present invention controls the drive of the registration roller and the relay roller, so that the conveyance performance is stable and the vertical magnification error of copy does not change for each sheet feeding unit. There is also an effect that there is no difference in the first copy time due to the length of the path between the paper feed roller and the registration roller.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of a sheet feeding section according to an embodiment of the present invention, FIG.
FIG. 3, FIG. 3 and FIG. 4 are views showing the paper conveyance states of different paper feed sections, respectively, (a) shows a bent state of the paper, and (b) shows
FIG. 5 is a diagram showing a driving state of the registration rollers, FIG. 5 is a diagram showing driving timing of each member in the sheet feeding unit 4, FIG. 6 is a diagram showing a drive system of the relay roller, and FIG. 7 is a one-way clutch of a gear. FIG. 1, 2, 3, 4 ... Feeding unit, 16, 17 ... Relay roller, 18 ... Registration roller

Claims (1)

[Claims] 1. A paper feeding device in a copying machine, a printing machine or the like, which is intermittently fed in order to align an image position with a paper position and to correct a leading end position and a bend of the paper in synchronization with an image forming system process. Registration roller, a paper detection sensor located in the vicinity of the upstream side of the registration roller, a paper feed unit that feeds paper from the paper stack at a speed faster than the process speed, and a conveyance length between the registration roller and the paper feed unit. Depending on the size, a drive system that is installed in the middle and that feeds paper at almost the same speed as the paper feed unit and a drive system that feeds paper at the same speed as the image forming system process speed are combined 1
A paper feeding device having one or more relay rollers and a paper guide unit having a space for escaping the deflection of the paper near the upstream side of the registration rollers.