JPH05193786A - Ultrasonic type two-sheet detecting method - Google Patents

Abstract

PURPOSE:To eliminate a need for a manual head paper sheet memory work by a worker and to prevent the occurrence of unevenness in a threshold by previously calculating a threshold common to all paper sheets, automatically setting the threshold during the start of a paper sheet feed part, and deciding whether the paper sheets are two or not in its number. CONSTITUTION:A two-sheet detector 21 sets a threshold common to all paper sheets by a CPU based on an approximately constant wave receiving voltage obtained from one paper sheet. When a paper sheet feed part is started after the start of a system, a set threshold is automatically set in the CPU in 'threshold automatic preset' of a process H. Thereafter, when paper sheets, which are decided as yes, in 'threshold <a wave receiving level' of process E pass the ultrasonic two-sheet detector 21 successively, a threshold by an average value of obtained wave receiving voltages, is decided by the CPU whether updating to 'wave receiving level * K a new threshold' is necessary or not. When there is a need for variation, updating to a new threshold is effected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic type two-sheet detecting method applied to a pre-printing apparatus of a sheet-fed printing press.

[0002]

2. Description of the Related Art A conventional offset sheet-fed printing press is shown in FIGS.
2, the offset sheet-fed printing machine has a paper feed unit 1, two printing units 2 and a paper ejection unit 3 as shown in FIG. The sheet is conveyed to the front hit device 6 by the endless tape 5 on the feeder board 4, and the front hit 7 (FIG.
The position in the advancing direction is regulated by the horizontal needle 8 (see FIG. 3).

Then, the tip of the swing gripper 11 is bitten and sent to the printing unit 2 which is a post-processing section.
It is printed and discharged through the paper discharge unit 3. As shown in FIG. 3, the detector holder 10 attached to the front contact plate 9 includes a register detector 12, a lateral needle detector 13, and an ultrasonic two-sheet detector 21a.
21c, the overtravel detector 15 and the like are attached.

FIG. 4 shows an ultrasonic type two-sheet detector 21a-21.
The details of c are shown. Reference numeral 20 is a control device, and ultrasonic waves (200 kHz) transmitted from a transmission circuit 27 of the control device 20 are transmitted via a cord 22 to a wave transmission sensor 23 attached to a detector bracket 19, and from the wave transmission sensor 23. It is sent to the wave receiving sensor 24 attached to the detector holder 18.

When one sheet is fed to this ultrasonic conveying path (see the solid line) and when two sheets are fed (see the alternate long and short dash line), the ultrasonic wave from the wave transmission sensor 23 is emitted. The state when received by the wave receiving sensor 24 is a solid line waveform and a one-dot chain line waveform, respectively, and the wave height of the one-dot chain line waveform is lower than the wave height of the solid line wave type. This state is sent to the determination device 26 of the control device 20 by the code 25, and it is determined here whether or not the number of sheets is two (if necessary, the actual application is 0).
1-036574)).

In order to set the detection wave height level of the wave reception sensor 24, which is the judgment reference, that is, the reception wave voltage serving as the threshold value, to the detection wave height level setting circuit 28 of the control device 20,
The sheet to be detected is manually transmitted / received by the wave transmission / reception sensor 23,
24, and the threshold value is obtained from the received voltage at this time. This operation is referred to as a manual top sheet storage operation.

FIG. 5 shows this manual leading paper storage operation. After the system is started, this "manual top sheet storage work" is performed in process A to set the threshold value (for the threshold value setting method, refer to Japanese Patent Application No. 03-022163.
See the specification). Next, the paper feed unit 1 is operated by the "feeder start" of the process B. When the process C receives the "two-sheet detection timing ON" signal, the "wave reception level detection" of the process D is performed. In the "threshold value (threshold value) <reception level" of the process E, the threshold value of A and the reception level of D are compared, and if the reception level is high, it is determined to be one (yes). ), Otherwise, it is determined to be two (no), and the process F is “fader stop”.
The paper feed unit 1 is stopped by.

Then, the two sheets (two sheets in which the sheet feeding unit 1 is stopped) are removed by G's "illegal paper removal work", and then the operation returns to "B feeder start" and restarts the operation.

[0009]

However, the above-described manual front sheet storage method has the following problems. That is, (1) Before the "feeder start" of the process B, the worker must always manually perform the manual top sheet storage operation (see FIG. 5). (2) When the worker performs the work described in (1) above, the thickness of the air layer between the two sheets caused by the stacking of the two sheets, and the two waves from the wave transmission sensor 23. The threshold value is likely to vary due to individual differences in the distance to the sheet. (3) The threshold value initially set as described above is used for a long time. On the other hand, the received voltage fluctuates even with the same paper due to environmental changes such as humidity and room temperature and fluctuations in the sheet density, so it is necessary to update the threshold value by following the fluctuations in the received voltage. Yes, but I cannot do this while driving.

The present invention has been proposed in view of the above problems, and its object is to eliminate the need for manual front paper storage work performed by a worker before a feeder start. Further, it is possible to eliminate variations in threshold value. Furthermore, an ultrasonic wave type 2 that can update the threshold value by following changes in the received voltage
The point is to provide a sheet detection method.

[0011]

In order to achieve the above object, the ultrasonic two-sheet detecting method of the present invention calculates a threshold value common to all sheets in advance and feeds it. It is characterized in that it is automatically set in the detection wave height level setting circuit of the control device at the time of starting the unit and whether or not the number of sheets from the paper feeding unit is two according to the threshold value.

In the ultrasonic two-sheet detecting method according to the present invention, the threshold value is changed for each sheet fed successively from the leading sheet from the sheet feeding unit. It is characterized by updating automatically following the.

[0013]

The ultrasonic two-sheet detecting method of the present invention precalculates a threshold value common to all sheets as described above, and this threshold value is set to the detection wave height level setting circuit of the control device at the start of the paper feeding unit. Is automatically set to determine whether or not there are two sheets from the sheet feeding unit based on the threshold value. Then, the threshold value is automatically updated in accordance with the fluctuation of the received voltage for each sheet that is successively sent out after the first sheet from the sheet feeding unit.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the ultrasonic type two-sheet detecting method of the present invention will be explained concretely with reference to FIG. This ultrasonic two-sheet detection method is a two-sheet detector 21 shown in FIG. 4 as an ultrasonic two-sheet detector.
To use. Since this two-sheet detector 21 can obtain a substantially constant received voltage for one sheet of paper regardless of the thickness, mass, color, etc. of the paper, all of them are preliminarily calculated based on this received voltage. The CPU calculates a threshold value (set threshold value) common to the sheets of paper.

In the "threshold automatic presetting" of the process H shown in FIG. 1 after the system is started, the set threshold is automatically set in the CPU when the paper feeding unit 1 is started. Then, the "feeder start" of the process B operates the sheet feeding unit 1. Process C
In response to the "2 sheet detection timing ON" signal, the "wave reception level detection" of the process D is performed.

Next, in process E, "threshold (threshold) <
"Reception level" is performed. That is, the leading sheet receiving level D sent from the sheet feeding section 1 is compared with the set threshold value H, and if the receiving level is high, it is judged as one sheet (yes).
s), the paper feed unit 1 is stopped by the F dust trap. Then, according to the process G “illegal paper removal work”, 2
The sheet of paper is removed, and then the process B is returned to the “feeder start”, and the operation of the paper feeding unit 1 is restarted.

The above processes B to G to B are the same as the process shown in FIG. The difference is that in the "threshold value (threshold value) <reception level" of the process E, when the sheets determined as yes sequentially pass through the ultrasonic two-sheet detector 21, the obtained reception wave is obtained. The level, that is, the received voltage is stored, and the threshold value based on the average value of these received voltages is updated by the CPU to “received level * k → new threshold value” of process I to obtain a new threshold value. The value I is compared with the set threshold value H or the threshold value based on the received voltage for each sheet due to environmental changes, and it is determined whether it is necessary to change,
If it needs to be changed, update to the new threshold.

The updated threshold value is returned to the entry side of the process C "two-sheet detection timing ON", and becomes a new detection level.

[0019]

As described above, the ultrasonic two-sheet detecting method according to the present invention calculates the threshold value common to all sheets in advance, and the threshold value is detected by the control unit when the sheet feeding unit is started. It is automatically set in the setting circuit, and it is determined whether or not the number of sheets from the sheet feeding unit is two according to the threshold value. Then, since the threshold value is automatically updated following the fluctuation of the received voltage for each sheet that is successively sent out after the first sheet from the paper feeding unit, before the start of the feeder. It is possible to eliminate the manual front paper storage work performed by the worker.

Further, as described above, the threshold value common to all the sheets is calculated in advance, and this is automatically set in the detection wave height level setting circuit of the control device at the start of the paper feeding section, so that it is manually performed. It is possible to eliminate the threshold setting by eliminating the threshold setting. Further, as described above, since the threshold value is automatically updated following the fluctuation of the received voltage for each sheet that is successively sent out after the first sheet from the paper feeding unit, The threshold value can be updated by following the fluctuation of the wave voltage.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of an ultrasonic type two-sheet detecting method of the present invention.

FIG. 2 is a side view showing an outline of an ultrasonic type two-sheet detecting device installed in a front printing device of a sheet-fed printing press.

FIG. 3 is a side view showing each detector installed in the front device.

FIG. 4 is an explanatory diagram showing an ultrasonic two-sheet detecting device.

FIG. 5 is an explanatory diagram showing a conventional ultrasonic two-sheet detection method.

[Explanation of symbols]

B Process of “Feeder Start” C Process of “Two-sheet Detection Timing ON” D Process of “Received Wave Level” E Process of “Threshold (Threshold) <Received Level” F Process of “Feeder Stop” G “ Process of “Unauthorized paper removal work” H Process of “Threshold (Threshold) automatic preset” I Process of “Reception level * k → New threshold” J Process of “Update threshold to new threshold (automatic storage of top paper)”

Claims (2)

[Claims] 1. A threshold value common to all sheets is calculated in advance, and this is automatically set in a detection wave height level setting circuit of a control device at the time of starting the paper feeding section, and the threshold value is set according to the threshold value. An ultrasonic type two-sheet detection method, characterized in that it is determined whether or not there are two sheets from the sheet feeding section. 2. The threshold value is automatically updated following the fluctuation of the received voltage for each sheet that is successively sent out after the first sheet from the sheet feeding section. The ultrasonic type two-sheet detecting method according to claim 1.