JPH0256713B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for determining the authenticity of magnetic printed matter such as banknotes and checks, and particularly to a method for determining the authenticity of magnetic printed matter such as banknotes and checks, and in particular,
The present invention relates to a method for determining the authenticity of magnetic printed matter used to determine the authenticity of banknotes in vending machines, etc., or to determine the authenticity of checks printed with magnetic ink.

Traditionally, the authenticity of banknotes has been determined using magnetic sensors and optical sensors that detect magnetic patterns (strength of magnetism) and optical patterns (colors) on arbitrary scanning lines (separate scanning lines or the same scanning line) of banknotes. , optical shading due to brightness and darkness), and converts the read output into a bit pattern of "0" and "1" by determining the read output using predetermined magnetic and optical threshold levels. Magnetism stored in memory in advance,
The optical reference pattern and the read magnetic and optical patterns are compared for each bit to determine whether they match or do not match. In this case, even if not all of the constituent bits of the pattern match, it may be determined that the patterns match if, for example, 90% or more of the bits match.
In this way, it is determined whether the magnetic and optical patterns match or do not match, and when both the magnetic pattern and the optical pattern are determined to be true, the banknote is determined to be genuine.

However, in the conventional authenticity determination method, which judges whether a pattern is "0" or "1" as described above, and independently performs the determination of the magnetic pattern and the optical pattern, There is a possibility that the copied banknotes cannot be identified. In other words, when the magnetic density of a color-copied genuine or fake banknote is close to the above-mentioned magnetic threshold level, there is a risk that the copied banknote will be mistakenly identified as a genuine banknote. If the above bits) match, it is considered true, which has the disadvantage that the possibility of misjudgment is even higher.

SUMMARY OF THE INVENTION In view of the above-mentioned problems with the conventional methods, it is an object of the present invention to distinguish magnetic printed matter such as banknotes and checks from counterfeit printed matter such as counterfeit banknotes produced by color copying.

In order to achieve the above object, the present inventors have conducted intensive research on methods for determining the authenticity of magnetic printed matter, and have found that magnetism is not detected in counterfeit printed matter, especially in color copy banknotes, regardless of the shade of color, etc., or While the intensity of the magnetic field is proportional to the intensity of the magnetic field,
In genuine printed matter such as genuine banknotes, there are parts where the magnetism becomes stronger as the color becomes darker, and parts where the magnetism becomes weaker even when the color becomes darker. The present invention was completed based on the knowledge that there are always parts where the strength and weakness do not correspond to the specific relationship as in the above-mentioned fake printed matter.

The present invention reads a magnetic pattern and an optical pattern on the same scanning line using a magnetic sensor and an optical sensor, superimposes the magnetic pattern and optical pattern on each other at the same detection point, and determines the level fluctuation. It is used to determine the authenticity of magnetic printed matter such as banknotes.

By doing this, in the case of counterfeit banknotes magnetically printed by color copying, the magnetic density and optical density are proportional, so when the magnetic pattern and the optical pattern are superimposed, the level of output of both patterns changes. will cancel each other out, and the first discriminating means will determine that the level fluctuations are minute, thereby distinguishing it from a counterfeit banknote.On the other hand, if it is a genuine banknote, even if the optical density is high, the magnetic field will be Since there is a weak portion, when the magnetic pattern and the optical pattern are superimposed, there is a portion where the level fluctuations of the outputs of both patterns do not cancel each other out, and in this case, the first determining means determines that a large level fluctuation is output. It is possible to identify genuine banknotes by checking this.

Furthermore, by combining the discrimination result of the first discrimination means and the discrimination result of the second discrimination means for discriminating the level fluctuation of the magnetic pattern, It is also possible to identify counterfeit banknotes.

Embodiments of the present invention will be described below with reference to the drawings.
In a method according to an embodiment of the present invention, as shown in FIG. 1, a printed matter 100 such as a banknote is moved at a constant speed in the direction of an arrow A, and is caused to pass a magneto-optical sensor 200 provided at a predetermined position. By detecting magnetic and optical patterns on the same track (scan line).

As shown in FIG. 2, the magneto-optical sensor 200 includes a magnetic sensor 201, an optical sensor composed of a light receiving sensor 202, and a light emitter 203.
The magnetic sensor 201 detects a magnetic field from a magnet (not shown) by passing it through the printed material 100, and outputs a signal corresponding to the concentration of magnetic components on the printed material. Further, although a transmissive type optical sensor is shown, a reflective type optical sensor may be used. However, when using a reflective optical sensor, the two reflective optical sensors read the front and back patterns, respectively.
The combination of the front pattern and the back pattern is an optical pattern. This is to match the magnetic pattern, which is always read by the magnetic sensor as both front and back sides. Furthermore, although the detection points of the magnetic and optical patterns of the printed matter are the same in FIG. 2, the detection points may be different as long as they are on a straight line with respect to the traveling direction of the printed matter. In this case, a delay line or a rotary encoder that outputs pulses synchronized with the conveyance of the printed matter (for example, one pulse for every 1 mm of conveyance of the printed matter) is used, and the output of the sensor in front in the direction of travel is transferred to both sensors. By delaying the detection points by the distance between them (by counting the output of the rotary encoder, etc.), the same effect as when the detection points are made the same can be obtained.

FIG. 3 shows a circuit for implementing the method of the invention. The circuit in the figure includes an amplifier 300 connected to a magnetic sensor 201 such as a magnetoresistive element or a Hall element, an amplifier 301 connected to a light receiving sensor 202, comparators 302 and 303 as first and second discrimination means, respectively; flipflop 30
4,305, summing amplifier 306, light source power supply 307 that supplies power to the projector 203, AND gate 3
08 etc.

In the circuit shown in FIG. 3, the output of the magnetic sensor 201 is amplified by the amplifier 300 to produce a magnetic pattern output 403, and the transmitted light of the printed matter from the emitter 203 is detected by the light receiving sensor 202 and amplified by the amplifier 301. Optical pattern output 40
4 is made.

The magnetic pattern output 403 is first input alone to the comparator 302 and is constantly compared with the threshold voltage THI, and when the magnetic pattern output 403 changes to become higher than the threshold voltage (threshold level) THI. Detection signal 4 becomes high level when
05 is made.

Magnetic pattern output 403 and optical pattern output 4
04 in the adder 306.
That is, these outputs 403 and 404 are input to an adder 306, and after each gain is adjusted, they are added together to produce an addition output 409. This gain adjustment is performed based on the fluctuation of the magnetic pattern output 403 of the amplifier 300 and the change in the magnetic pattern output 403 of the amplifier 300 when the detection point read by the magnetic sensor and optical sensor moves from a light-colored, weakly magnetic area to a dark-colored, strongly magnetic area. The gain of the adder 306 is adjusted so that the fluctuations in the optical pattern output 404 cancel each other out, that is, so that the output of the adder 306 does not fluctuate from a predetermined output level when the color is light and the magnetism is weak. The addition output 409 is input to the comparator 303,
A detection signal 40 that is compared with a constant threshold voltage TH2 and becomes high level when this addition output 409 changes to be lower than the threshold voltage TH2.
6 is created.

Note that the gain adjustment described above may be performed by adjusting the gains of the amplifiers 300 and 301 instead of adjusting the gain of the adder 306, or in combination with this. Furthermore, in this embodiment, since the variation polarity (convex) of the magnetic pattern output 403 of the amplifier 300 and the variation polarity (concave) of the optical pattern output 404 of the amplifier 301 are opposite polarities (the direction of change is opposite),
An adder 306 is used to superimpose these magnetic patterns and optical patterns.
If the fluctuation polarities of both pattern outputs are the same polarity (the direction of change is the same), they can be superimposed by taking out differential outputs using a differential amplifier.

Each of the detection signals 405 and 406 is sent to the flip-flops 304 and 305, which are reset at an appropriate timing, for example, after pattern reading is completed or immediately before the next banknote pattern is read.
The output 40 of each of these flip-flops 304 and 305 is stored by an AND gate 308.
7 and 408 and determine output signal 41
Get 0. This output signal 410 becomes "1", that is, a high level, only when the bill or the like is true, and becomes "0", that is, a low level, when it is false.

Next, the operation of the circuit shown in FIG. 3 will be specifically explained using examples shown in FIGS. 4 to 6. In these figures, a shows an example of a printed matter pattern, and the reading track is shown by a dash-dotted line. b is the magnetic pattern output 403, c is the optical pattern output 4
04 and d indicate the addition output 409, respectively.

In FIG. 4, a is an example of a genuine banknote, and 112 of the printed portions is a portion containing a large amount of magnetic ink sufficient to fluctuate to exceed the threshold voltage TH1;
Portions 111 and 113 do not contain magnetic ink, or contain only a small amount of magnetic ink below the threshold voltage TH1. That is, 111 and 113 are dark colored but magnetically weak parts, and 112 is a dark colored and magnetically strong part. Note that the other white areas are pale (bright) in color and have very weak magnetism. Therefore, the level of the magnetic pattern output of b increases by a portion of 112. The output of the optical pattern c corresponds to the brightness and darkness of printing, with bright areas having a high level of output, and the output decreasing as it gets darker. Therefore, when the outputs of b and c are combined, the part 112 is canceled as shown in d.

In FIG. 5, a indicates a magnetic copy of the printed matter shown in FIG. 4 a, and 121,1
Both parts 22 and 123 have magnetism. Therefore, the level of the magnetic pattern output increases in all parts as shown in b, and has a waveform that is opposite to the optical pattern output shown in c. Therefore,
The added output becomes a substantially flat, high-level value, although there is some waviness, as shown in d.

In FIG. 6, a indicates a copy of the printed matter shown by a in FIG. 4 by copying without general magnetic ink, and the portions 131, 132, and 133 also have no magnetism. Therefore, as shown in b, there is no magnetic pattern output, and the optical pattern output c and the addition output d show the same waveform.

Therefore, in the case of FIG. 6, the magnetic pattern output does not become higher than the threshold value TH1, so the flip-flop 304 of FIG. 3 is not set. In addition, in the case of FIG. 5, since the addition output does not become lower than the threshold value TH2, the flip-flop 3 of FIG.
05 is not set. In addition, in the case of the printed matter shown by a in FIG. 5, if the magnetic density is quite high, the addition output becomes quite high as shown in d in FIG. 7, so the flip-flop 3
05 is not set, and conversely, if the magnetic density is quite low, the magnetic pattern output will be lower than the threshold value TH1 and the flip-flop 304 will not be set, or the addition output d will not be set as shown in FIG.
Each threshold value TH is set so that flip-flop 305 is not set due to
By setting 1 and TH2, it is possible to prevent both flip-flops 304 and 305 from being set at the same time. Therefore, only in the case of FIG. 4, both flip-flops are set and the discrimination output signal 410 becomes "1".

In the circuit of FIG. 3, instead of the flip-flops 304 and 305 and the AND gate 308, there is a program memory (ROM) that stores a program, a microprocessor (CPU) that operates according to the program stored in the ROM, and a data A control means consisting of a data memory (RAM) for storing the comparator 30 is provided.
The output of 2,303 is checked, and when each comparator becomes high level, the corresponding flag (placed in RAM) is set, and if both flags are set at the end of reading, it is a genuine print. It may also be determined.

Alternatively, the outputs of the amplifier 300 and the adder 306 may be sampled, AD converted, input to the control means, and sequentially stored in the RAM. In this way, comparators 302 and 303 are not required.

Of course, the present invention can be implemented alone, but it may also be used in conjunction with the determination of "0" and "1" of the bit pattern described in the prior art example. This allows for a more accurate determination of authenticity. in this case,
The denomination can be determined by determining whether the bit pattern is "0" or "1". Note that “0” in the bit pattern
When implementing the present invention alone without using the determination of "1" in combination, the denomination can be determined by inspecting the length of the banknote.

When applying the present invention to checks, bills, etc. that have a clear band printed with magnetic ink, the amount field, payer's address, and name field that do not include magnetism must be written in black (dark color). Authenticity can be determined by detecting the presence of a clear band containing magnetic ink and printed in a dark color.

As described above, according to the present invention, a magnetic sensor and an optical sensor are arranged on the same scanning line to read the magnetic pattern and the optical pattern on the same scanning line, and the magnetic pattern and the optical pattern are placed on the same detection point. Since the two images are superimposed on each other and their level fluctuations are determined by the first determining means, it is possible to identify false printed matter that has been color-copied with magnetic printing as shown in FIG.

Furthermore, by providing a second discriminating means for discriminating the level fluctuation of the magnetic pattern, and discriminating authenticity based on the discrimination results of the first discriminating means and the second discriminating means, magnetic printing as shown in FIG. It is also possible to identify fake printed color copies.

[Brief explanation of the drawing]

FIGS. 1 and 2 are explanatory diagrams showing the positional relationship between each sensor and a printed matter for carrying out a method according to an embodiment of the present invention, and FIG. FIGS. 4 to 8 are waveform diagrams for explaining the operation of the apparatus shown in FIG. 3. 100... Printed matter, 200... Magneto-optical sensor, 201... Magnetic sensor, 202... Light receiving element, 203... Emitter, 300, 301... Amplifier, 302, 303... Comparator, 304, 305
...Flip-flop, 306...Summing amplifier,
307...Power source for floodlight, 308...And gate.

Claims (1)

[Claims] 1. A magnetic sensor and an optical sensor are provided on the same scanning line for a magnetic printed matter, and the magnetic sensor and the optical sensor read a magnetic pattern and an optical pattern on the same scanning line, and the magnetic pattern and the optical pattern are read. A method for determining the authenticity of a magnetic printed matter, wherein the authenticity of the magnetic printed matter is determined by superimposing optical patterns on the same detection point and determining the level fluctuations thereof using a first determining means. 2. A magnetic sensor and an optical sensor are provided on the same scanning line for a magnetic printed matter, the magnetic sensor and the optical sensor read a magnetic pattern and an optical pattern on the same scanning line, and the magnetic pattern and the optical pattern are made to be the same as each other. The magnetic patterns are superimposed on a detection point and their level fluctuations are determined by a first determining means, and the level fluctuations of the magnetic patterns are determined by a second determining means, based on the determination results of the first determining means and the second determining means. A method for determining the authenticity of magnetic printed matter by using a method of determining authenticity of magnetic printed matter.