JPS6023238A - Sheet feeder - Google Patents

Abstract

PURPOSE:To fix the transport start position and to keep the sheet feed interval constant by advancing a sheet from a loading portion in the transport direction and once stopping the sheet at a transport start position to start transporting the sheet in a fixing timing. CONSTITUTION:A sheet feeder includes sheet feeding means 2 for feeding sheets sheet by sheet and a pair of transport rollers 6, 7 which are disposed at a fixed distance from the sheet feeding means and always rotated in the sheet translower than the sheet transport speed of the sheet feeding speed. The feeder further includes sheet detectors 13, 14 for detecting the sheet fed out by the sheet feeding means 2. At a point of time when the sheet detector detects the trailing edge of the preceding sheet, the sheet feeding means 2 starts to feed out the succeeding sheet, and at a point of time when the sheet detector detects the leading edge of the succeeding sheet, the sheet feeding means 2 is temporarily stopped. After a fixed time from the point of time of stopping, which is set in such a manner that at least the succeeding sheet does not catch up with the preceding sheet, the sheet feeding means is again operated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a paper feeding device, and particularly to a paper feeding device that can shorten the paper feeding interval.

[Prior Art] In recent years, the processing speed of devices that form hard copies using cut sheets, such as copying machines and printers, has improved, and their work efficiency has improved. Along with this, it is necessary to increase the paper feeding speed of the paper feeding device that supplies cut sheets to the recording section in these devices, and therefore there is a demand to shorten the paper feeding interval as much as possible.

However, in order to make the paper feeding interval extremely short (for example, 30+ nm or less), there are problems as in the conventional method.

■Normally, in a paper feeding device, the paper (cut paper) loaded on a paper feeding table etc. is separated one by one by a paper feeding mechanism consisting of a paper feeding roller and a separating and conveying means, and the device rotates at a constant speed at all times. The paper is conveyed to an intermediate roller pair, and then further conveyed to a next-stage conveyance roller pair (for example, a register I roller pair in a copying machine).

Therefore, when multiple sheets of paper are fed by the paper feed roller, the paper feed start position is different for the first sheet and subsequent sheets, and as a result, paper feed control cannot be performed under the same conditions.
The spacing between the sheets may vary, and there may even be a situation where the sheets partially overlap between the pair of conveying rollers.

■ The separating and conveying means uses the frictional force generated between the separating roller and the paper and the difference in the frictional force acting between the papers to separate the paper sheet by sheet, and as a result, the separation between the separating roller and the paper A slip phenomenon always occurs.

The amount of slip that occurs between the separation roller and the paper due to this phenomenon is due to factors such as differences in the surface friction coefficient and material depending on the type of paper, stiffness, pressure on the separation roller, etc. It varies significantly, such as ~40%.

Therefore, the time required to move from the transport means to the pair of intermediate rollers changes, causing a problem in that the intervals between the bound sheets vary.

[Objective] The present invention solves the above-mentioned problems, and by setting the position of the paper at the time when the paper is separated one by one by the paper feeding means as the starting position of paper feeding control, the paper interval can be kept constant, and the paper feeding It is an object of the present invention to provide a paper feeding device that can shorten the interval.

[Description] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic diagram showing a main part of an embodiment of the present invention, which constitutes a paper feeding section of a copying machine.

In the figure, 1 is a paper contact plate that aligns the leading edges of the stacked papers PA, 2 is a paper feed roller that sends out the papers PA sequentially from the top, and 3 and 4 are separating and conveying means that separate the papers PA one by one. These are a non-separable roller and a non-separable roller, and the non-separable roller 3 is interlocked with the paper feed roller 2, and the non-separable roller 4 is stopped.

5 is a guide plate that guides the paper PA sent out by the paper feed roller 2 to the separation roller pair, 6 and 7 are intermediate rollers that are constantly rotating in the direction of the arrow, and 8 is a guide plate that guides the paper PA from the separation roller pair to the intermediate roller pair. A guiding plate 9 and IO are registration rollers 11 that send the paper PA to a transfer section (not shown).
12 is a guide plate that guides the paper PA from the pair of intermediate rollers to the pair of registration rollers, and 12 is a guide plate that guides the paper PA to the transfer section.

Paper sensors 13 and 14 for detecting the paper PA are arranged immediately after the pair of separation rollers and immediately before the pair of intermediate rollers, respectively. Note that this paper sensor x3. x4 consists of an optical sensor or a microswitch whose detection signal has high-speed rising and falling characteristics. In addition, the circumferential speed of the separation roller pair is
It is set faster than the circumferential speed of the intermediate roller pair.

FIG. 2 shows the control system of this embodiment. As described above, this embodiment constitutes the paper feeding section of the copying machine, and is therefore controlled together with other parts 21 of the copying machine by the main body control section 20 of the copying machine. Further, 22 is an operation display section of this copying machine, which includes various operation keys such as a number key, start key, mode selection key, etc., and various indicators such as a number display, a jam indicator, a paper out indicator, etc. It is provided.

The main body control unit 20 controls a paper feed clutch 23 that applies power to the paper feed roller 2 and the bisecting roller 3 based on the states of detection signals Sl and S2 applied from the paper sensors 13 and 14.
And the logic level of the control signals SC and S] of the registration clutch 24 that powers the registration rollers 9 and 10 is changed.

With the following configuration, when the operator presses the start key on the operation display section 22, the main body control section 20 controls each section 21 of the copying machine.
After completing the initial processing, start copying process control,
Synchronizing with this, the logic level of the signal SC is set to ``old'' at time 1 (see Fig. 3 (a)).As a result, the paper feed clutch 23 is turned on, and the paper feed roller 2 and the non-separable roller 3 are turned on. The paper rotates, and the top paper PAL is fed out and separated.

Then, as shown in FIG. 4(a), the paper PAI is detected by the paper sensor 13 and its output signal S1 (FIG. 5(b)
When the logic level of (reference) becomes "■", at this point L2, the main body side a11 section 20 sets the logic level of S to "L" and stops the paper PAI. As a result, the paper PA1 is positioned at the transport start position. be done.

Thereafter, at a predetermined time point 3 synchronized with the copying process, the main body control section 20 again sets the logic level of the signal S to [Old] and starts transporting the paper FAI.

When the paper PAI is detected by the paper sensor 14, the output signal S2 becomes the logic level "old" (see FIG. 3(c)), and the output signal S2 changes from this point L4 until the paper PAI is nipped by the intermediate rollers 6.7. 1 main body control unit 20 at time L5 when time has elapsed
sets the logic level of signal SC to rLJ. After this, the paper 1) AI is moved to the intermediate roller 6°7 as shown in FIG. 4(b).
When the registration timing tr is reached,
The main body control section 20 sets the logic level of the signal SR (see FIG. 3(d)) to "old" and operates the registration rollers 9.lO, thereby transporting the paper PAL to the transfer section by the registration rollers 9 and 10. be done.

As shown in FIG. 4(c), at the point 6 when the trailing edge of the paper PAL passes through the paper sensor 13, the main body control unit 20 sets the logic level of the signal SC to "old" and starts the next paper PA2. When the leading edge of the paper PA2 is detected by the paper sensor 13 at 7, the logic level of the signal SC is set to rlJ and the paper PA2 is positioned at the conveyance starting position in the same way as for the paper FAI.

Then, at time 8, when a predetermined time Td has elapsed from time 7, the main body control unit 20 sets the logic level of the signal SC to [old] and starts transporting the paper PA2 (see FIG. 4(e)).
.

The subsequent paper PA2 is conveyed under control in the same manner as the paper PAL.

As with this paper PA2, the paper that follows this paper PA2 starts feeding when the trailing edge of the preceding paper passes the paper sensor 13, is once stopped at the conveyance start position, and then starts from this stopping point. When the time Td has elapsed, the sheet is conveyed again to the intermediate roller 6.7 by the sheet feed roller 2 and the upper separation roller 3. After that, it is conveyed to registration rollers 9 and 10 by intermediate rollers 6.7,
It is conveyed to the transfer section by registration rollers 9 and 10.

Note that the time Td is set so that the circumferential speed of the separation roller pair is higher than the circumferential speed of the intermediate roller pair, so that the following paper does not catch up with the preceding paper, and the paper interval is kept at a predetermined size. is set to

In the embodiment described above, the paper sensor 14 is provided to detect the off timing of the paper feed clutch 23, but the paper sensor 14 can also be made unnecessary by managing the on time of the paper feed clutch 23. . Note that the paper sensor 14 may be used for jam detection.

[Effects] As explained above, in the present invention, after the paper is stopped at the transport start position which is advanced in the transport direction from the stacking position,
Since the conveyance is started at a predetermined timing, the conveyance start position is constant, and the paper feeding interval can be kept constant. Further, since the conveyance path accompanied by the slip phenomenon is shortened, the influence of slip rate fluctuations can be reduced, and errors in paper feeding intervals can be suppressed to a small level. For these reasons, there are advantages in that the paper feeding speed can be increased and the paper feeding interval can be shortened.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing one embodiment of the present invention, FIG. 2 is a block diagram illustrating a control system, and FIGS.
Waveform diagram 4 to explain the operation of the control system shown in the figure.
Figures (a) to (e) are schematic diagrams showing how each part is controlled. 2...Paper feed roller, 3...Upper separation roller, 4...
Lower roller, 6, 7...Middle roller, 9, 10...
・ Toji roller, 13.14...paper sensor, 20
...Body control unit, 22...Paper feed clutch, 23...
・Resist clutch.

Claims (1)

[Scope of Claims] (1) A paper feeding means that feeds stacked sheets one by one, and a paper feeding means disposed at a predetermined distance from the paper feeding means, and conveying the paper at a peripheral speed slower than the paper transporting speed of the paper feeding means. a pair of transport rollers that constantly rotate in the direction of the feeder, and a paper detector that detects the paper fed by the paper feeder, and from the time when the paper detector detects the trailing edge of the preceding paper, the paper feeder detects the trailing edge of the paper fed by the paper feeder. At the same time, when the leading edge of the following paper is detected by the paper detector, the paper feed means is stopped, and the paper is fed again after a predetermined period of time. A paper feeding device characterized by operating paper means. (2. Scope of the Claims In claim 1, the paper feeding device is characterized in that the predetermined time is set so that at least the following paper does not catch up with the preceding paper. (3) Scope of the Claims 2. The paper feeding device according to claim 1, wherein the pair of conveying rollers is an intermediate roller pair provided between the paper feeding means and the next stage conveying means.