JPS6040073B2 - Abnormal transfer detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an abnormal transfer detection device for detecting abnormal transfer of paper sheets, and more particularly to a multi-feed detection device in which a plurality of paper sheets are transferred in an overlapping manner.

In currently known printing machines and copying machines, most of the paper for printing (paper sheets) is supplied using cut paper, but due to the quality of the paper or the overlap of the paper in the paper feeding device. Due to various reasons, it is currently impossible to avoid double feeding of paper (meaning that sheets of paper that should normally be fed one by one are fed one after the other).

Double feeding is not a problem for low-speed printers and copiers with a small number of copies, but paper feeding in high-speed and unmanned output devices, such as high-speed printing devices used as computer output terminals, is a problem. Double feeding, such as the above, causes misalignment or omission of printed characters, which deteriorates the operating efficiency of the device and causes a lot of waste. Especially if the printing device works online,
It is extremely difficult to detect misaligned or omitted characters, and they can be fatal defects. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to overcome the drawbacks of the prior art described above and to provide an abnormal transfer detection device for detecting abnormal transfer of recording paper, particularly double feeding, in a printing machine or a copying machine.

The abnormal transfer detection device of the present invention will be explained in more detail below with reference to the drawings. FIG. 1 is a schematic block diagram of an abnormal transfer detection device according to an embodiment of the present invention.

Reference numeral 1 in FIG. 1 is a detection circuit that combines a light-emitting element and a light-receiving element, and outputs a voltage level change caused by the passage of paper between the light-emitting element and the light-receiving element.

2 is a differentiating circuit that detects the voltage change time obtained from the detection circuit 1, and 3 is a shaping circuit that shapes the differential pulse of the output 2 of the differentiating circuit.

4 is a reference signal generation circuit for forming a reference signal generated for each sheet of paper to be transferred in order to command paper feeding;
A determination circuit 5 determines the paper detection signal derived from the shaping circuit using this reference signal as a reference, thereby determining whether or not double feeding has occurred.

6 is a warning circuit that warns that double feeding has occurred.

FIG. 2 shows in more detail the case where the abnormal transfer detection device shown in FIG. 1 is applied to an electronic copying machine.

7 is a picture paper cassette, and this paper feed cassette 7 has a bottom plate 9 pressed vertically by a spring 8, and papers (paper sheets) 10 stacked on the bottom plate 9. This is what we are doing.

Above the paper feed cassette 7 is a roller 11 which is constantly rotating in the direction of the arrow 5 and which can be pressed onto the paper 10 by a plunger 12 or pulled away from the paper 10 as shown by the solid line. 13.

By pressing the paper 10-1 at the upper end of the paper feed cassette with the roller 11, the paper 10-1 is transferred to the right in FIG. 2, passing between the guide plates 14 and 15. , a pair of timing rollers 16 that normally do not rotate,
The tip is inserted into 17. Paper manipulated like this 1
After the paper 10-1 is inserted between the timing rollers 16 and 17, by driving the plunger 12 and pulling up the roller 11, the paper 10-1 can be directly transferred to the right by driving the timing rollers 16 and 17. It becomes a state.

In addition, after the paper 10-1 reaches a predetermined position by moving the roller 11,
To pull up the paper 10-1, a timer is used to move the roller 11 up and down the paper 10-1 for the time required for the paper 10-1 to reach the state shown in the figure.
The timing rollers 16 and 1 may be pressed together.
It may be configured such that the insertion of the paper 10-1 into the paper 10-1 is detected by a light emitter and a light receiver (not shown), and the roller 11 is pulled up. In this state, the timing roller 16
, 17 in the direction of the arrow, the paper 10-1 passes between the guide plates 18 and 19 and reaches the top of the photosensitive drum 20, and is then moved onto the photosensitive drum 20 by a developing device 20-1 of a known electrophotographic apparatus. The toner adhering to the paper 10-1 is transferred onto the paper 10-1 by a known transfer device 20-2.

It goes without saying that the paper 10-2 to which the toner has been transferred in this manner is fixed by a fixing device (not shown). On such a photosensitive drum 20, in order to form a static crab latent image, a switch is turned on with recording information.
Since the laser beam 21 is irradiated with -OFF modulation, certain information can be written by this laser beam 21 (assuming that this laser beam is deflected at a constant period in a direction perpendicular to the plane of the paper). The commotion of the timing rollers 16 and 17 must be started in correlation with the start of compression.

(The photosensitive drum 20 is driven at a constant speed.) That is,
Assuming that the feeding speed of the paper 10-1 by the timing rollers 16 and 17 is equal to the circumferential speed of the photosensitive drum 20, the leading edge of the paper sent between the guide plates 18 and 19 by the timing rollers 16 and 17 in the direction of the photosensitive drum When the information reaches the photosensitive drum 20, the leading edge of the information recorded by the laser beam 21 must reach the location indicated by arrow A.

At this time, the area between arrows A and B will form the top margin formed at the top of the paper. In this embodiment, the length of the paper path between the timing rollers 16 and 17 and the point indicated by arrow 8 on the photosensitive drum 20 is equal to the distance between arrows A and C on the photosensitive drum 20, so that
At the same time as the laser beam 21 starts recording a page on the photosensitive drum 20, the driving of the timing rollers 16 and 17 starts. Furthermore, this timing roller 1
The timing rollers 6 and 17 are controlled so that their driving is stopped when there is no longer any paper between the timing rollers 16 and 17, and the plunger 2 of the feeding roller 13 causes the timing rollers 6 and 17 to start driving. Then, after a certain period of time, the roller 11 is pushed down to transport the sheet of paper to the right in the figure. Through holes 24 and 25 are provided in the opposing positions of the guide plates 18 and 19 as described above, and a light emitter 22 and a light receiver 23 are provided in each of the through holes.

The light emitter 22 and the light receiver 23 are provided as shown in FIG. 3, and the paper 10-1 travels in the direction of the arrow P between them. Reference numeral 26 indicates a resistor, and the light emitter 22, light receiver 23, and resistor 26 constitute the detection circuit 1 shown in FIG.

The capacitor 27 and the resistor 28 are the differentiator circuit 2 in FIG.
By differentiating the signal at point a,
This is to obtain a differential output to be applied to the transistor 29 constituting the shaping circuit 3.

The output of such transistor 29 is a flip-flop 30.
The output of the flip-flop 30 is applied to an AND gate 31 as well as a monostable multipipelator 32, and the output of this monostable multipipelator is also applied to the AND gate 31.

The output of the band gate 31 is applied to a warning device 33-1, and is also output on a line 33-2 as a drive signal to a mechanism to be driven (for example, a paper removal mechanism) when double feeding occurs. .

Note that the clear terminal 34 of the flip-flop 30 has the following:
Reference signal generation circuit 3 that should serve as a reference for paper feed timing
Apply the reference signal from 5.

In the embodiment, the reference signal generator 35 consists of a command signal generator that instructs the laser beam 21 to start recording information on a certain page; however, the reference signal generator 36 is not necessarily required. The command signal is not limited to such a command signal, and may be a signal that notifies that a certain point on the photosensitive drum 20 has reached a specific position, for example. However, in such a case, the start of recording on the photosensitive drum by the laser beam is controlled by the notification signal,
Furthermore, the start of driving of the timing rollers 16 and 17 is also controlled by the notification signal.

The output of the reference signal generator 35 is applied to the clear terminal as described above and also applied to the set terminal of the flip-flop 36, and this set output is applied to the timing roller 6.
, 17 drive circuits (not shown).

The flip-flop 36 is reset by a detection signal that detects that no paper is present between the timing rollers 16 and 17.

The operation of the abnormal transfer detection device having the above-mentioned configuration is explained in the fourth section.
This will be explained in more detail with reference to the drawings.

In FIG. 4, n indicates a state in which the sheets of paper (nl, n2, . . . ) are being fed at equal intervals by the timing rollers 16, 17.

When paper is being fed normally one by one, nl, n2, n4
However, in the case of double feeding, it will be sent as shown in n3. The cause of such transport is that the two sheets of paper are fed between the guide plates 14 and 15 by the roller 1. Now, as shown in Figure 4n, when the paper is being transported, the signal waveform at point a in Figure 3 is the 4th waveform.
As shown in Figure a, when the light receiver 23 is blocked by a sheet of paper, it outputs an output at the AL level, and when it is not blocked, it outputs an output at the A2 level, but double feeding occurs. Since the light is blocked by two sheets of paper in the area where the light is displayed, an A3 level output is derived.

By introducing such output a into a differentiating circuit and detecting the point of change in the output level by the optical receiver, at point b of the differentiating circuit, a signal waveform as shown in Fig. 4b is obtained, and such a signal is By applying the voltage to the transistor 29 and shaping the waveform, it is possible to obtain a signal waveform with only a component changing in one direction from point c as shown in FIG. 4c.

4d shows the reference signal derived from point d in FIG. This is derived prior to paper detection by .

As is clear from the figure, when paper is being fed normally, there is only one detection signal for one reference signal, but when paper is fed multiple times, there is only one detection signal for one reference signal. 2
Therefore, there are two detection signals.

Therefore, by counting the number of detection signals with respect to the reference signal, it is possible to know whether double feeding has occurred or not.

Since the shaped detection signal and reference signal are applied as input signals and clear signals to the flip-flop 30, a signal waveform as shown in FIG. e is obtained from the output of the flip-flop 30.

Furthermore, since the shaped paper detection signal is applied to the monostable multipipe plate 32 which generates a pulse with a pulse width T4, a pulse as shown by f can be obtained from this multipipe plate plate 32. be. However, the above T4
is made smaller than the interval T3 between the shaped detection pulse and the subsequent reference pulse when making continuous copies in the copying apparatus shown in FIG.

Therefore, by applying the outputs of the flip-flop 30 and the monostable multipipulator 32 to the AND gate 31, the output from the AND gate is as shown in FIG. 4g.
It is possible to derive a notification signal to notify that multi-feeding has started.

The notification signal obtained in this manner may be applied to a warning device 32 consisting of a lamp or a buzzer, or may be applied to a discharge mechanism (not shown) for discharging double-fed sheets. It is also good to derive it as a drive signal for driving. According to the above embodiment, if the two sheets of paper that are double-fed are shifted considerably, the double-feed may not be detected, but experiments have shown that in double-feed, the two sheets of paper are In most cases, the misalignment occurs, and if there is a large misalignment, the paper will overlap with the next paper, so this is a paper feeding error rather than a double feed, and this paper feeding error can be detected using a general-purpose paper. Since it is installed in a copying machine or the like, it can be detected by such a device.

Note that the period indicated by r4 is the period for detecting double feeding, but T
4=T2, and if the relationship T2<T3<TI is maintained, all double feeds that do not overlap with the next paper to be fed will be detected.

However, TI is the time it takes the paper to pass through the detection circuit, and T2
is the time between sheets being fed.

FIG. 5 shows still another embodiment of the present invention, in which the output of the shaped paper detection pulse at point c in FIG. 3 is applied to the terminal 37, and this detection signal is When a predetermined number of pulses are counted after being input to the terminal 39, the pulses are introduced into a counter 38 (in the embodiment, the pulse output is derived from two pulse inputs) which derives the pulse output. The output of this counter 38 is applied to four latch circuits, and this latch circuit 401 is directly applied with a reference signal from a reference signal generator 41 similar to the reference signal generator 35 as a clear signal. At the same time, the reference signal is also applied to the counter 38 as a load pulse. The output of the latch circuit 40 is sent to the warning device 42 as a signal to notify that there is a double feed as shown in FIG.
It is applied to To explain in more detail with reference to the signal waveform in FIG. 6, as explained in FIG. As a pulse, Fig. 6k
Since a reference signal as shown in FIG. 6 is applied, a pulse signal can be obtained as an input to the latch circuit 40 only at the position where double feeding starts as shown in FIG. 6i.

Therefore, as the output of the latch circuit 40, it is possible to obtain a signal i that rises at the pulse i and falls at the reference pulse k1.

Therefore, the pulse output i can be used as a drive signal for the warning device 42 or a double-feed elimination device (not shown). As described above, according to the present invention, the first level change of the detection signal from the detection means for detecting the paper hollyhock body is detected and the first signal is outputted, and the second level change is detected and the second signal is outputted. double feeding determining means for determining that a paper collection has been double fed when the signal generating means outputs a first signal due to the first level change and a second signal due to the second level change; Therefore, it is possible to detect double feeding that cannot be detected by a sheet jam detector, and furthermore, it is possible to detect double feeding extremely accurately.

[Brief explanation of the drawing]

FIG. 1 is a block diagram schematically showing the abnormal transfer detection device according to the present invention, FIG. 2 is a partially sectional side view of a copying machine to which the present invention is applied, and FIG. 3 further illustrates the abnormal transfer detection device according to the present invention. A concrete block diagram, FIG. 4 is a signal waveform diagram in each part of the device shown in FIG. 3, FIG. 5 is a block diagram showing still another embodiment of the present invention, and FIG. is the fifth
FIG. 3 is a signal waveform diagram at each part of the device shown in the figure. Here, 1 is a detection circuit, 2 is a differentiation circuit, 3 is a shaping circuit,
4 is a reference signal generation circuit, 5 is a determination circuit, and 6 is a warning circuit. Figure 2 Figure 3 Figure 4 Younger brother Figure 5 Figure 6

Claims (1)

[Claims] 1. A detection means for detecting a sheet of paper; and a first signal formed by a first level generated by the detection operation of one sheet of paper by the detection means; a signal generating means for outputting a second signal formed by a generated second level different from the first level;
1. An abnormal transfer detection device comprising double feeding determining means for determining double feeding of paper sheets when a signal is output within a predetermined time.