JPS59108644A - Double-feed detecting system for sheet rotary press - Google Patents

Abstract

PURPOSE:To make the double-feed of paper detectable without fail, by setting the subtractive value between an almost mean value of a transmittable light quantity in both cases of one piece and two pieces and the transmittable light quantity in case of one piece, while finding a reference value in a way of subtracting this value from the transmittable light quantity, and comparing it with the existing paper transmittable light quantity. CONSTITUTION:An output circuit is turned to ON with a signal out of a paper detecting circuit PD, while a transmittable light quantity Dn of paper by a light receiver LR is outputted from a processor part PRS and if the first paper is the case, a subtractive value Ln is generated out of a subtractive value generator SNG. This subtractive value Ln is set with an almost mean value of a transmittable light quantity transmitting one and two sheets of paper as a reference value, which becomes a value showing a difference in both cases between one and two pieces and one piece alone in the transmittable light quantity. Then, the value of Dn-Ln is found with an operator OP, and if the Dn is within the specified range at a selector SEL, it is set down to the reference value and stored in a memory MM and from the second one downward are renewed likewise. Comparing this value with the transmittable light quantity transmitting the existing paper, whether the present quantity of light is double feed or not is judged. Thus the influence of a variation in transmittivity of the paper can be eliminated and a state of double feeding can be detected without fail.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a two-sheet difference detection method used in a sheet-fed rotary printing press to detect that two or more sheets are fed simultaneously.

In a sheet-fed rotary printing press, if two or more sheets of paper are fed at the same time and a two-sheet discrepancy occurs, this is detected and the operation of the printing press is stopped. The means whose principles are shown in FIGS. 3 to 3 have generally been adopted.

That is, Figures 1 to 3 show the relationship between the light transmittance α of paper and the amount of transmitted light, and when there is only one sheet of paper, the relationship of fiD = α with straight line A is established. In contrast,
If there are two sheets of paper, the relationship between the direction of curve B and D = α2 will be established. Focusing on the change in the amount of light, 2 will be calculated according to this value.
It is designed to detect the sheet difference.

However, in Fig. 1, the detection level Ld, which is semi-fixed according to the thickness and quality of the paper, is used as a reference, and the difference between two sheets is detected based on this.
The detectable range DE is small, the detection level Ld must be adjusted each time the type of paper is changed, and it is not possible to respond to changes in conditions over time.

In addition, in Fig. 2, processing such as averaging is performed on the amount of transmitted light up to the previous time, and after memorizing the result, the detection level Ld is set. Although the DE is large, it has a drawback that it is impossible to detect the difference between two sheets in a range of transmittance α close to 100 degrees and a range close to 0%.

In addition, in FIG. 3, the υ detection level Ld is set at a constant ratio to the stored value in the same way as described above.
Although the detectable range DE is expanded in FIG. 2, there is a drawback that it is impossible to detect the difference between two sheets in a range where the transmittance α is close to 100 degrees.

The present invention has the purpose of fundamentally eliminating the drawbacks of the conventional methods, and aims to reduce the amount of transmitted light that passes through one sheet of paper to a value that is approximately intermediate between the amount of transmitted light that passes through two sheets of paper. In addition to determining a reference value to indicate the amount of light transmitted through one sheet of paper, a subtraction value is determined to indicate the difference between this reference value and the amount of transmitted light transmitted through one sheet of paper, and this subtraction value is subtracted from the amount of transmitted light transmitted through the paper to calculate the actual value. This extremely effective sheet-feed system calculates the reference value of Rotary printing press 2
This provides a sheet difference detection method.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to figures showing embodiments, but the present invention will be described in detail without further ado.

Fig. 4 is a diagram similar to Figs.
The reference value Mn is set on the curve showing D-α-t, which is an intermediate value between the curve B showing the amount of transmitted light transmitted through a sheet of paper, and the value of the straight line A and the reference value Mn are A subtraction value n is determined that indicates the difference between ing.

Therefore, the subtraction value Ln is set according to the light MD, and the reference value Mn is successively determined by calculating Dn-Ln-=Mn, and this and the amount of light transmitted through the current paper are calculated. Dn+
1, and if it is determined that the condition Mr+≧Dn→1 has been met, the detectable range DE is approximately 0% of the transmittance α.
Expanded to 100 inches.

However, as shown by the dotted line p, almost the same result can be obtained even if the reference value Mn is approximated by a straight line depending on the range of the transmittance α.

In addition, as shown in Fig. 5, which shows an enlarged range of low transmittance α, for paper with low transmittance α, when there is a difference between two sheets, the curve B based on the theoretical value is
Since the curve Br based on the actually measured values shows a low value, it is preferable to change the reference value Mn to Mnr and set the subtraction value Ln accordingly for paper with a low transmittance α.

In addition, in the figure, Ad, Mnd, Bd, etc. indicate changes when quantized by digital conversion.

From FIG. 6 onwards, examples will be shown based on the above principle.
Fig. 1 is a mechanical configuration diagram, in which the paper 2 sent out from the paper feed table 1 is fed onto the difference plate 3, the head is captured by the swing claw 4, and the paper is moved between the blanket cylinder 5 and the impression cylinder 6. In addition to being supplied to the blanket cylinder 5, the plate cylinder 7 receives the printing of the image transferred from the plate cylinder 7 to the blanket cylinder 5.
is perforated, and a floodlight LG is provided on the bottom side of the difference plate 3.
The emitted light passes through the paper 2 and is received by the light receiver LR,
It is converted into an electrical signal.

Further, the impression cylinder 6 is provided with a driving body such as a protrusion not shown in the figure, and the rotation of the impression cylinder 6 is detected by a detector TD such as a proximity switch installed opposite to this, and the rotation of the printing press is detected. A synchronized pulse signal is obtained.

Fig. 7 is a block diagram showing the electrical configuration.
The output of R is given to a processing unit PR8, where it is converted into a digital signal indicating the amount of transmitted light, and is also processed by a selector SEL using a decoder etc., a comparator CP, an arithmetic unit OP using a subtracter etc. And a subtraction value generator S using memory etc.
Given to NG.

1, the arithmetic unit OP subtracts the output of the subtraction value generator SNG from the output of the processing unit PR8, and gives the subtraction result to a memory unit MM such as a latch circuit, and the memory output of this is sent to the comparator CP.
It is compared with the output of the processing unit PR8, and the comparison output is sent out as the detection output Do of the difference between the two sheets via an output circuit OC such as an AND gate.

Note that the selector SEL generates an output when the output of the processing unit PR8 is outside a predetermined range, and this output is given to the memory unit MM via a memory controller MC such as an OR gate.
In addition to blocking the storage operation of the output of the arithmetic unit OP by M, the comparison output of the comparator cp is also given to the storage device MM via the storage controller MC, thereby preventing the storage operation in the same way.

On the other hand, a paper detection circuit P using a Schmitt trigger circuit etc.
The output of the light receiver LR is also given to D, and when this output becomes below a predetermined level, the paper detection circuit PD generates an output, which is given to the output circuit OC, and the output is sent to the detector TD.
The timing signal generated by the timing signal generator TSG in synchronization with the output of cp is also given to the output circuit OC, and when the two match, the output circuit OC is turned on, and the comparator cp
The comparison output is sent out.

However, the timing signal generator TSG generates various glue/timing signals and supplies these to the processing unit PR8, the subtraction value generator SNG, the memory MM, etc., and thereby regulates the operation timing of each part. In addition, a changeover switch SW is provided that is operated according to the type of paper 2, and controls the light source surrounding power supply LPS to vary the luminous intensity of the light source LG, as well as a selector SEL and a subtraction value generator. a predetermined range in the output of the processing unit PR8, which controls the selector SNG and is monitored by the selector SEL;
The range of the subtraction value Ln indicated by the output of the subtraction value generator SNG is varied.

FIG. 8 is a block diagram showing the details of the processing unit PR8, in which the output of the photoreceiver LR is amplified to a predetermined level by the amplifier AMP after noise components are removed by the transducer FIL, and the output from the receiver LR is amplified to a predetermined level by the amplifier AMP. It is averaged by an averaging circuit AVR using an analog-to-digital converter (hereinafter referred to as
ADC) A/D": 9, timing signal generator rsG
>) and are converted into digital signals in accordance with the timing signals.

Figure 9 shows the operation of ADC-A/D and the subtraction value generator SNG.
This is a timing chart showing the relationship between the ADO-A/D conversion operation (b) and the timing signal (al) being applied for the nth and (n+1)th time. Correspondingly, the subtraction values Ln and Ln
The generation of +1 (e) is repeated.

To generate the subtraction value, store the subtraction value corresponding to the light intensity in each address of the memory, specify the high-order bit of the address number with the changeover switch SW to determine the range of the subtraction value, and then use the ADC-A. This is done by specifying the lower bits of the address number by outputting /D and reading out the stored contents.

FIG. 10 is a flowchart showing the operating status of FIG. YES), 'output circuit ON'
is carried out, and the amount pn of the transmitted light transmitted through the operation paper 2 is sent out from the processing unit PR8 for "ADC operation".
Is paper 2 the first sheet? ', then the subtraction value generator SN
1 subtraction value is generated from G, and the light amount Dn is sent to the arithmetic unit OP.
and the subtraction value Ln are given, so here Dn-
1 calculation of Ln is performed, and the selector SEL determines whether the light amount Dn is within a predetermined range. The reference value Mn indicated by is stored in the memory MM.

Also, if paper 2 is the second or subsequent sheet, is it '1st sheet? " is N
If (No), a 2-subtraction value is generated in the same way as described above, and at this time, since the light amount Dn-) 1 and the subtraction value Ln+1 are given to the arithmetic unit OP, the reference value Mn+1 is given from the arithmetic unit OP. The output shown is generated, ゞMn≧Dn+1'','
The contents of the memory device MM are updated and stored by "Storage" after passing through "Do sending" and "Y of "Storage possible?".

However, prior to this, the light amount 1)n+1 and the reference value Mn indicated by the contents of the memory MM are given to the comparator CP, so a comparison is made that ゞMn≧pn+1'', and the result of this is Y. If so, through the output circuit OC in the on state,
Detection output ``DO transmission'' is performed.

Furthermore, can you remember? The comparison output of the comparator CP is also involved in the determination of ``.

Ushibu ζ-15 paper available? At N of "and detection timing?", (ζ) is 1, "output circuit OFF" is performed, and transmission of unnecessary signals is prevented.

By repeating the above operation across L, the optimal reference value Mn is automatically determined according to the light transmitted through the paper 2 from diMI to iD, and the current light is determined based on this. A judgment is made as to whether or not 1) indicates a two-sheet difference, and the result shown in FIG. 4 is realized.

Alternatively, a rotary encoder or the like may be used as the detector TD, and the subtraction value generator SNG in FIG.

Arithmetic unit op, memory unit MM, comparator cp, selector SEL
, 4C equal to 12, microprocessor, memory, etc. to the storage controller -\↑N may be replaced, and it is also optional to realize the function equivalent to that in Fig. 7 with an analog circuit, and the present invention is a divine modification. is free.

As is clear from the above explanation, according to the present invention, the optimal reference value is automatically determined, so that hl due to changes in light transmittance of paper and change due to changes in various conditions over time are eliminated. The difference between two sheets can always be detected reliably, and a remarkable effect can be obtained in various sheet-fed rotary printing presses.

[Brief explanation of the drawing]

Figures 1 to 3 are diagrams showing the principle of the conventional example, Figures 4 and 5 are diagrams showing the principle of the present invention, Figures 6 and after show examples of the present invention, and Figure 6 is a machine 7 is a block diagram showing the electrical configuration, FIG. 8 is a block diagram showing details of the processing section, and FIG. 9 is a timing chart showing the relationship between the operation of the ADC and the operation of the subtraction value generator. FIG. 1o is a flowchart showing the operating status of FIG. 2...Paper, 3a...Through hole, LG...° Emitter, LR...Receiver, PR8...Processing unit, SN
G: Subtraction value generator, op: Arithmetic unit, M
M...Memory device, CP...・Comparator, A/D...ADC (appogog digital converter). Figure 1 □ Be I%J Figure 2 → O/[%] Figure 3 → Be [%J 412'1

Claims (1)

[Claims] The amount of transmitted light transmitted through one sheet of paper and the amount of transmitted light transmitted through two sheets of paper are the difference between the reference value indicating the value between the values and the amount of transmitted light transmitted through one sheet of paper. Determine a subtraction value that indicates the value, subtract the subtraction value from the amount of transmitted light that has passed through the paper to obtain the actual reference value, and compare the induced reference value with the current amount of transmitted light that has passed through the paper. A two-sheet difference detection method for a sheet-fed rotary printing press, characterized in that a difference between two sheets of paper is detected.