JPS589988B2 - Device for determining whether printed matter is correct or incorrect - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for determining whether a printed matter is good or bad, or whether it is genuine or false.

There are various methods to determine whether a printed matter is correct or not, but the method involves detecting physical quantities such as transmitted light, reflected light, or magnetic content of the target printed matter, and comparing this detected physical quantity with a preset threshold for determining whether the printed matter is genuine. There are many methods for determining whether a target printed matter is correct or not.

This conventional example will be explained in more detail and its problems will be clarified.

FIG. 1 is a block diagram of a conventional method for determining whether a printed matter is correct or not.

In this figure, B is a printed matter to be determined, and these specific parts, for example, Pl, P2, P3, . A spot from a light source is applied to P4, and the transmitted light or reflected light is received by a photoelectric body (not shown).

Dl, D2. D3 is a comparison circuit such as a differential amplifier, and the signal voltage e1 from the photoelectric body corresponding to the specific portion P1 is applied to one of the comparison input terminals of each comparison circuit, and the signal voltage e1 from the photoelectric body corresponding to the specific portion P1 is applied to the other input terminal. P3. Similar signal voltages e2+e31e4 from P4 are applied respectively.

Sl, S2°S3 are comparison circuits D1. D2. A discrimination circuit that receives the output signal of D3 as input, and an upper limit discrimination circuit S11 individually.
．． S21°S31 and lower limit discrimination circuit S12. S22. S3
It is equipped with 2.

A is an AND circuit which inputs the outputs of the upper and lower limit discriminating circuits and outputs an identification signal.

The operating criteria for each discrimination circuit is determined as follows.

When the target printed material is a predetermined reference printed material, the signal e of each specific portion is el<e2<e3<e4 as shown in FIG.
Assuming that, the output of the comparison circuit Di +D2 +D3 is e2e1゜e3-el as shown in Fig. 3a-c.
, indicates the level based on e4-el.

Furthermore, el depends on factors such as whether the reference printed material is new or old.

Since e2 + e3 + e4 varies to some extent, in consideration of this, the discrimination level is provided with a width as shown by diagonal lines in FIG. 3.

That is, the upper limit of each level is determined by an upper limit discriminating circuit so that a pass signal is not issued above this level, and the lower limit discriminating circuit of each level is determined and a pass signal is not issued below this level.

This method is described in detail in Japanese Patent Publication No. 41-20245.

We have described typical conventional examples of determining whether a printed matter is correct or not, but there are the following problems with devices that detect some physical quantity from the target printed matter and compare it with a predetermined discrimination level to determine the correctness. There is a point.

■ As mentioned in the explanation of the conventional example above, there are variations in the detected amount, so it is necessary to have a range in the discrimination level, but what value this discrimination level should be set to is conventionally generally based on experience and intuition. The decision was made by trial and error.

Therefore, a lot of time is required for adjustment, and variations occur in the adjustment results, leading to serious maintenance problems.

■ Discrimination level width of the discrimination device (the shaded area in Figure 3 is extremely important in determining the performance of the discrimination device; if the discrimination level width is too narrow, the rate of rejecting genuine printed matter (rejection rate) will increase; On the other hand, if the discrimination level width is too wide, the rate at which unauthentic printed matter is erroneously determined as genuine (misjudgment rate) increases.

Although in principle there is an optimum value for the discrimination level value, it is very difficult to set the discrimination level to this optimum value using conventional devices.

■ In order to improve the pass/fail discrimination performance, the width of the discrimination level (shaded area in Figure 3) is improved while keeping the rejection rate within the allowable range.
must be set as narrow as possible.

On the other hand, variations in the detected physical quantity occur due to the adhesion of dust or dirt to the photoelectric part of the device or changes over time in the light source or light receiver, but in this case, this directly leads to an increase in the rejection rate and the misclassification rate.

In other words, with conventional equipment, it is difficult to achieve both high performance and high stability, and attempting to achieve high performance requires frequent cleaning and readjustment of the equipment, which causes many operational problems.

This invention has been made to solve the problems of the conventional printed matter discriminating devices as described above, and the object thereof is to provide a printed matter discriminating device with good operability and high reliability.

According to the present invention, the first operation mode includes a means for detecting the statistical characteristics of the detected physical quantity of printed matter, and automatically sets the discrimination level based on the above-mentioned statistical value, and By providing a second operation mode that automatically corrects the discrimination level by estimating it from the value, we aim to improve operability and reliability.

The details of the present invention will be described below based on examples.

FIG. 4 is a diagram showing an embodiment of the printed matter discrimination device of the present invention.

In this figure, 1 is a printed matter to be discriminated, and 2 is a detection device, which detects the amount of three-color separated reflected light (R, G, B) of a specific portion on the printed matter in this embodiment.

Although not shown in the figure, the printed matter 1 passes in front of a detection device 2 that is successively conveyed by a conveyor belt.

Among the printed matter that passes one after another in this way, the figure shows the i-th printed matter, and the detected amount from this first printed matter 1 is xll,
1. Shown as X31.

3 is a photoelectric switch that detects the shadow of the printed material 1 being conveyed and generates a printed material edge signal T.

Output. 4 is a counter for the number of printed matter to be determined, and outputs a count value N.

5 is a timing control circuit, which outputs control timing signals T1.5 for controlling various circuits in subsequent stages. T2.
Output T3.

6 is a 3-channel multiplexer, 7 is a 10-bit A/D converter, and the multiplexer 6 outputs the 3-channel detection signal X1 under the control of the timing signal T1.
8. X21. X31 is converted into a time series signal y, and the A/D converter 7 converts the signal y into 1 under the control of the timing signal T1.
Convert to digital signal 2 of 0 bits and 3 words.

Reference numeral 8 denotes an arithmetic control unit, whose arithmetic control details will be described later, but it calculates the statistical value of the detected amount according to the specified operation mode, calculates the discrimination level, sets it in the discrimination level storage device, and calculates the discrimination level correction. and changes the contents of the discrimination level storage device.

Reference numeral 9 denotes a discrimination level storage device, which is a 16-bit, 6-word random access memory.

The contents of the memo l)-Ml, M2...M6 are the detected amount X1. X2. These are the upper and lower limit discrimination levels for Xs.

Reference numeral 10 denotes a 16-bit D/A converter, which converts the stored contents of the storage device 9 into analog quantities and converts them into Ll, Hl; L, respectively.
2. H2:L3. Output H3.

L and H are the lower limit discrimination level for the detection amount X, respectively;
This is the upper limit discrimination level.

11 is a statistics storage device, which stores the average value X1 of each detected amount.
, X2, and X3 are stored.

This is a 16-bit 3-word RAM.

12 is a designation switch 12-1 that designates two operation modes (first operation mode and second operation mode) of this device;
and a command switch 12-2 that instructs the arithmetic and control unit to operate.

The meaning of each switch will be explained later.

13. 14 and 15 are comparison/discrimination circuits, and the detection amount x3
(j=1.2.3) and upper/lower limit discrimination levels Hj and Lj, and outputs a comparison discrimination output W.

When L1≦X,≦Hj, the discrimination output Wj=1, and in other cases, Wj=O.

16 is an AND circuit which synthesizes the outputs of the three comparison circuits 13 to 15 and outputs a comprehensive discrimination output (2) of the printed matter 1.

That is, when all three detected values are within the lower/lower limit level, the overall discrimination output ■=1; otherwise, it is V-O.

The main parts of FIG. 4 will be explained in more detail below.

Operation mode designation switch 12-1 in switch mechanism 12
is a switch that specifies two operating modes (a first operating mode and a second operating mode) of the device, and is, for example, a two-contact rotary switch.

In the first operation mode, the arithmetic and control device 8 calculates the average value (xj) and variance (σ) of each detected amount (Xj, i) of N printed matter.
, the maximum value (rTlaXJ), and the minimum value (minj), and from these values, the upper/lower limit discrimination level H for each detection amount is determined.
Hj, Lj are determined and stored in the discrimination level storage device 9.
is set, and the average value is set in the statistics storage device 11.

The memorized contents are HOJ・L OJ y x
It will be O.J.

In the second operation mode, the arithmetic and control device 8 calculates the average value (xj) of each detected amount (Xji) of N sheets (1000 sheets in the example) of printed matter, and stores the value X0j in the statistics storage device 11
If there is a difference, the storage contents of the discrimination level storage device 9 are corrected according to the value of the difference.

In this second operation mode, the content of the discrimination level storage device 9 and the detected amount of each printed matter are compared and discriminated by the discrimination circuits 13, 14, and 15, and a comprehensive discrimination output (■) is output. Printed matter with V=O) are excluded from the above average value calculation.

Control command switch 12-2 in switch mechanism 12
is a switch for externally instructing the start of the arithmetic control operation in the first operation mode and the second operation mode, and is, for example, a single-point bushing switch.

Until this command switch is pressed, the arithmetic and control unit 8 records the amount of printed matter detected, and when the data recording is completed and the command switch is pressed, the arithmetic and control unit 8 receives a signal from the command switch. The above-described discrimination level setting process or discrimination level correction process is started.

The start of such discrimination level setting processing or discrimination level correction processing is automatically started when the number of recorded data reaches a predetermined number N0, that is, N-No (for example, No. 1000), without using an external command or switch. Even if the arithmetic processing unit 8 is configured to start the above processing automatically, the same effect can be obtained.

In the second operation mode, the discrimination levels Li, Hl (i=
1 to 4) have already been set in the discrimination level storage device 9, the correctness discrimination output V can be obtained for each printed matter through the comparison discrimination circuits 13, 14, 15 and the AND circuit 16.

Next, the operation of the arithmetic and control unit 8 will be described in detail.

If the first operation mode is specified, the arithmetic and control unit 8
When a calculation start command is sent from the control command switch 12-2 at the stage when the printed matter (detected amount from printed matter that is sequentially passed through) has been passed through, the arithmetic control unit 8 starts the calculation process, and first calculates the average value 71 and The standard deviation σi is determined by the following relationship.

This calculation result x1. x2. x3. σ1. σ2. Discrimination levels 71, 12, 13 and hl, h2 of each detection amount from σ3
Determine ゜h3 from the following relationship.

In this formula, nl, n2, n3 and ml, m2. m
3 is a preset value, and in the example, n1=n
2=n3=m1=m2=m3=40.

The arithmetic and control unit 8 includes the above-mentioned 11, 12, 13. hl, h2
．． h3 is set in the discrimination level storage device 9, and the average value
．． X2. X3 Statistics 5 Set in storage device 11.

For convenience of explanation, the values set in each storage device are
ol, lo2. lo3゜hol, ho2. ho3 and x
It is represented by the symbols ol, XO2, and x03.

The above is the operation of the arithmetic unit 11 control device 8 when the first operation mode is specified, and the arithmetic control device 8 having such a function can be easily realized using a known microprocessor.

If the second operation mode is specified, the arithmetic and control unit 8
The detected amount from printed matter that is passed through sequentially is output as a judgment result of whether it is correct or not (V-O), so if it is judged as negative (V-O), the detected value of that printed material is calculated from the above simple sum. exclude.

When M prints (1000 sheets in the example) are passed through, when a calculation start command is input, the calculation and control unit 8 starts the following calculation and control units.

First, the average value X1 is determined using the following relationship.

If the number of samples M is large enough, around 1000 sheets, the average value Xi is considered to be a value unique to printed matter, and if fluctuations appear in this average value, it is likely due to fluctuations in the detection device (discoloration or stains on the standard white board, etc.). Responsible.

This average value and the past average value x01 stored in the statistics storage device 11. x02. x03, and if there is a difference, the discrimination level is newly revised using the following formula.

11=lo1. (Ma Q = B 1)/k, h, -hol,
(X, 7x,, 1:)zk4=102. (X2 Xo2
)/k, 112=)1o2. (Xz−諷ｚ)／に１
3=llos, (Xs-s)/'k, h3-
Instigation, (Y3 two circles, the above calculated IJ 1, l
2, 13: Set h 1 r h 2 and h 3 in the discrimination level storage device 9, and newly write l.

1°102 +103' hol 1h021h03
shall be.

Regarding the average value, the corrected average value a1, 32T is calculated using the following formula.
Find 33.

al-ma.

1+(Ma]X.,)/ka2-Yo2+(Ma2
X02)/k a3 = ”03, (”3-ma03)/and a
l, a2. Set a3 in the statistics storage device 11 and enter Y again.

1. father. 2. Ma. Set it to 3. Here, k is a damping factor for correction, and in the example, it was set to =5.

In general, if the number of samples M is large enough, around 1000 sheets, the average value of the detected amount will be almost the same for any group of 1000 sheets, but there is a certain amount of variation, and the dispersion of the average value of these samples will cause the discrimination level to change rapidly. It is necessary to provide a damping factor to prevent this from being modified.

The above is the operation of the arithmetic and control unit 8 in the second operation mode.
Repeatedly execute one after another (in units of 0 sheets).

A device having the above functions can be easily realized using a known microprocessor.

In the example, in the first operation mode, the average value of the detected amount Y
and standard deviation σi, discrimination level 11. Although hl has been determined, the maximum value maXi or the second maximum value maxX of the detected amount
2j, and the minimum value In + 111 or the second minimum value m1n21, etc., and from these values, l + ""
mlni=σi/ahi=max;
The effects of the present invention can be sufficiently obtained even if the discrimination level is determined as a i/a or by a combination of both.

The effects of the present invention will be explained below using an operation example.

When paying attention to the detected amount X1 in the embodiment of FIG.
The frequency distribution of the detection amount X1 of 00 genuine samples is the 5th
The result is as shown by curve 50 in the figure.

The average value found by the arithmetic and control unit 8 in the first operation mode for such 1000 samples is x1=11
75, and the standard deviation is σ1-46.

11=x, -4σ1. The lower and upper discrimination levels determined by hl-x1+4σ1 are shown in the figure, and the area between 11 and hl is the discrimination area for genuine printed matter, and all of the detections of the 1000 samples were within the genuine area. It can be seen that there is no extra genuine note area and the discrimination level of 111 hl has been appropriately determined.

On the other hand, when determining the discrimination level by considering a certain variation in the detection value Xa of the standard sample and taking into account the width of ΔX, it is fine if Xa happens to be close to Xl, but m
1nX1 or rna X X ], the determined discrimination level is clearly not optimal.

FIG. 5 shows the case where xa=1250+Δx=225, but in this case, the upper limit discrimination level clearly includes an extra area.

Furthermore, the size of ΔX must be determined entirely by trial and error.

This trial and error process generally takes a considerable amount of time.

FIG. 6 shows the progress of correction of the discrimination level with respect to the detection amount X1.

In this figure, 60 is the upper limit discrimination level h.

1 is the elapsed time, and 61 is the average value stored in the statistics storage device 11.

1 is the elapsed time, 62 is the elapsed time of the average value X1 of the detection amount obtained in units of 1000 sheets, and 63 is the lower limit discrimination level l.

1 represents the passage of time.

In addition, this figure shows the results of setting the discrimination level (first operation mode) at time t=0 and then entering the second operation mode to correct the discrimination level. Approximately 5 times for determining the integrity and authenticity of printed matter
It takes minutes.

Therefore, the detection of the average value of 1000 prints and the accompanying correction of the discrimination level are also performed at approximately 5 minute intervals.

The reason why the average value X1 fluctuates as shown in FIG. 6 is due to the temperature characteristics of the detection system as the temperature of the device increases and the adhesion of dust to the detection device.

If the method of correcting the discrimination level based on the average detection amount is not adopted, the range of the discrimination level that should be set will be the range shown by the dotted line 64 due to various temporal fluctuation factors, but this will be wider than the original true region 65. Since it includes an extra range, there is a high possibility that an object that is negative in terms of correct/incorrect discrimination will fall into the positive discrimination area, and as a result, the correct/incorrect discrimination performance becomes low.

Furthermore, if the range shown in 6-7 is set as the authenticity determination area in order to improve the authenticity determination performance, the rejection rate will increase as time passes from the start of work, making continuous use of the machine impossible.

On the other hand, in the discrimination device according to the present invention, each detected amount (X
Regarding l), the average value for every M sheets (1000 sheets in the example) is calculated, and if there is a difference from the average value stored in advance, the discrimination level is corrected, so time 1 = 0.
The optimal discrimination level determined by is maintained.

In this case, since there is a means for taking the average value of a sufficiently large number of printed matter, it is not affected by variations in individual printed matter.

As described in detail above, according to the present invention, it is possible to achieve a device for determining whether a printed matter is correct or not, which has high correctness judgment performance and high reliability.

In the above-described embodiment, the correct or incorrect determination was made by detecting the color of the printed matter, but it goes without saying that other physical quantities such as magnetic quantity may also be used.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram of a conventional printed matter discrimination device;
3 and 3 are explanatory diagrams of operations in the conventional method, FIG. 4 is a diagram showing an embodiment of the printed matter discrimination device of the present invention, FIG. 5 is a diagram showing a specific example of detection data in the device of the present invention, and FIG.
The figure is a diagram for explaining the process of correcting the discrimination level in the apparatus of the present invention. 1... Printed matter, 2... Detection device, 3... Photoelectric switch, 4
...Number of sheets counter, 5...Timing control circuit, 6...
... multiplexer, 7 ... A/D converter, 8 ... arithmetic control device, 9 ... discrimination level storage device, 10 ... D/A converter, 11 ... statistics storage device, 12 ... switch mechanism, 13 to 15... Comparison/discrimination circuit, 16... AND circuit.

Claims (1)

[Scope of Claims] 1. In a device that detects physical quantities such as the color and magnetic content of a printed matter and compares the quantities with a pre-stored discrimination level to determine whether the printed matter is correct or not, this device enables
Means for determining statistical values such as an average value and standard deviation obtained from the detected amounts of a plurality of printed matter that should be determined as "correct" or determined as "correct," and determining the discrimination level based on the statistical values. What is claimed is: 1. An apparatus for determining whether a printed matter is correct or not. 2. In a device that detects a physical quantity such as the color or magnetic content of a printed matter and compares the amount with a pre-stored discrimination level to determine whether the printed matter is correct or not, the first operation performs initial adjustment of the device. A means for specifying a mode and a second operation mode in which normal discrimination work is performed is provided, and when the first operation mode is specified, the statistical value of the detected amount of multiple printed matter that should be determined as "correct". is determined, this statistical value is stored, and a discrimination level is determined based on this statistical value, and when the second operation mode is specified, the detection of multiple printed materials that are discriminated as "correct" according to the discrimination level is performed. An apparatus for determining whether a printed matter is correct or not, characterized in that a statistical value of a printed matter is obtained, and when a difference between this statistical value and the stored statistical value is equal to or greater than a predetermined value, a predetermined discrimination level is corrected.