JPS59201177A - Paper sheet recognizer - Google Patents

Abstract

PURPOSE:To eliminate effectively the rubbing noise of a paper sheet and to improve the discriminating accuracy for the type of a bank note with the use of a magnetic detecting means by counting a pulse given from a duty ratio discriminating means and comparing the counter output with the data on a comparison dictionary provided within a memory means. CONSTITUTION:A paper sheet 3 on a base 1 is slided toward an arrow A-A and carried to the position of a magnetic detecting means 4, and a sliding scan is given to the width and lengthwise directions of the paper sheet 3. The means 4 delivers an analog signal in which a detection pulse MP having a comparatively regular cycle is mixed with a detection noise PN. Then only a prescribed frequency component is extracted out of said analog signal by an amplifying circuit 5 including a BPF and applied to a comparator 6. The comparator 6 compares the frequency component with the prescribed function 7 to deliver the pulse MP and the noise PN having a level higher than a threshold value. This output is applied to a duty ratio discriminating circuit 8, and the output of the circuit 8 is counted by a counter circuit 9. Then the count value of the circuit 9 is compared with the comparison dictionary data 11 within an ROM through a count value comparator 10. Thus the discriminating accuracy is increased for the types of money.

Description

Detailed Description of the Invention (1) Technical Field of the Invention The present invention relates to a recognition device for magnetically printed paper sheets, particularly the sliding that occurs when magnetically printed paper sheets are detected by a magnetic detection means. This invention relates to a recognition device that removes the influence of noise.

(2) Background of the technology Conventional recognition devices for distinguishing between paper sheets as objects to be recognized, such as banknotes of different denominations, detect magnetically printed patterns using magnetic detection means such as magnetic heads. , the analog detection output detected by the magnetic detection means is passed through a bandpass filter including amplification for a predetermined band frequency, and then the reference slice level is set to a predetermined darkness value and the bandpass filter A serial pulse train is obtained, which is added to a counter circuit, and the count value is compared with dictionary data, etc., and the part of the banknote is discriminated based on its size. Another discrimination method is to divide a predetermined width of a banknote into a plurality of zones by scanning it with a magnetic detection means, and compare the distribution of the pulse appearance positions within the zone division with a reference value. It discriminates whether the banknote has magnetic printing or not, or whether the denomination of the banknote is 14.

However, such conventional denomination discrimination or magnetic printing presence/absence discrimination has the following problems and has the disadvantage that the discrimination sensitivity cannot be increased.

(i) Since the pattern is drawn on a single banknote by intaglio printing, when a magnetic head, etc., which is a magnetic detection means, is slid along the paper surface of the banknote to detect the pattern of the magnetically printed part, the pattern is created by intaglio printing. The detection pulse (sliding noise) and the detection pulse of the magnetic printing part are mixed, reducing detection accuracy.

(11) Since the frequency of sliding noise is spread over a wide range, it cannot be completely removed using only a bandpass filter.

When we consider banknotes as sheets of paper, some have magnetic printing and some do not, depending on the denomination, but some banknotes that do not contain magnetism have a large amount of sliding noise.

Figure 1 (al) shows the magnetic sensor output at the same location on the same banknotes with and without conventional magnetic printing, with the width of the banknote on the horizontal axis and the output level on the vertical axis. Yes, pulse noise detected at a predetermined slice level S L or higher (I) N means sliding noise mainly detected by the D2 magnetic detection stage (magnetic nozzle) that slides on the intaglio-printed banknote surface Although it is unclear whether this is the case or why it is detected by the magnetic head, the unevenness of intaglio-printed banknotes is generally about 70 μm at maximum, and the vibrations caused by these unevenness can cause the magnetic detection means to detect the unevenness. The explanation has been that it is a shock noise that occurs when the installation is moved.

When viewed as a pulse train, the pulse noise PN at the slice level S I- or higher shown in Fig. 1 (a) (bl) is randomly distributed in the scanning direction of the banknote width, and its period is large, at least about 1 mm. It has a cycle of more than

(3) Purpose of the Invention The present invention takes into account the above-mentioned drawbacks and focuses on the fact that the detection pulses of a magnetically printed pattern partially have periodicity and the sliding noise does not have periodicity. It is an object of the present invention to provide a paper sheet recognition device that improves the accuracy of banknote denomination discrimination using a θ magnetic detection means by efficiently removing sliding noise of paper sheets. It is something.

(4) Structure of the invention and the above-mentioned object according to the present invention include the above-mentioned detecting means for discriminating the authenticity of the paper Tffi≦ that is generally fed by the general feeding means, and the output of the magnetic detecting means being predetermined. Comparing means for comparing the output with the dark value, extracting a value less than the dark value, converting it into a binary value and outputting it; duty ratio discriminating means for extracting only pulses having a predetermined tute ratio or more from the output of the comparing means; This is achieved by providing a paper sheet recognition device characterized by comprising a comparison means for comparing the output of the counting means for counting pulses from the ratio discrimination means with comparison dictionary data in the storage means.

(5) Examples of the invention Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a system diagram of the present invention, FIG. 3 is a waveform explanatory diagram of FIG. 2, and FIG. 4 is a specific configuration example of the duty ratio discrimination circuit of the present invention. In FIG. 2, reference numeral 1 designates a base on which a paper sheet 3 such as a banknote, which is an object to be recognized, is slid in the direction of the arrow by a conveying means 2 such as a roller or a bell 1, and the (general conveying means 2
For example, it is driven by a conveying means having a driving means such as a morph (not shown). If the magnetic detection means 4 is a magnetic head or a hall element, etc., it is a paper sheet 3. If it is a magnetic head, the magnetic detection means 4 is a paper sheet 3. According to the movement of the sheet holding means 2 in the eight-input direction, the sheet is slidably scanned in the width or length direction of the sheet.

As mentioned above, there is a magnetic printing part on sheet 3, as shown in Figure 3.
As shown in a+, the detection pulse MP has a partially relatively regular period corresponding to the pattern interval of the magnetic printing part, and the detection called sliding noise that occurs when the magnetic detection means 4 slides on the surface of the paper sheet 3. An analog output waveform in which fins PN are mixed can be obtained.

Such a detection output is transmitted to an amplifier circuit 5 including a bandpass filter.
In addition to that, a predetermined frequency component is passed through jffi, and is applied to the comparison circuit 6 after amplification. The comparator circuit receives a dark value symbol SL from a reference level generating circuit 7 set to a predetermined dark value as shown in FIG. 3 (bl), and extracts detection pulses PN and MP that are higher than the dark value level. These five signal components are waveform-shaped by a waveform shaping circuit, etc., and then binarized and converted into a serial pulse train as shown in FIG. The duty ratio discrimination circuit 8 allows only pulses with a specific duty ratio close to a period having a duration determined by the pattern interval of the magnetically printed portion of the paper sheet to pass through.

In this way, a detection pulse MI) corresponding to the magnetically printed portion can be extracted from the output of the duty ratio discrimination circuit 8, as shown in FIG. 3Fdl. The number of detection pulses MP extracted in this way is counted by the counter circuit 9 and stored in a storage means such as a ROM (read only memory) of a computer, which is determined according to the type of banknote.
The count value of 1f'' is compared with the output of the dictionary zone 11 by the count value comparison counter 1-circuit 10 to output a determination output 13 for determining the denomination of the eagle leaf.

Reference numeral 12 denotes a zone division signal generation circuit which determines the banknote width Wo to be scanned by the magnetic detection means from W1 to W as shown in FIG. 3fdl.
Divide 6 into n equal zones and divide the zone into i! Groups corresponding to each iJ zone! The number of pulses (f;) is determined in advance and the number of pulses is counted and compared for each zone WI to W6, and such a comparison may be performed.

Further, as an example of the above-mentioned duty ratio discrimination circuit, the fourth
It can be configured as shown in the figure.

That is, FIG. 4(b) shows the waveforms of each part ■ to ■ of FIG.
A one-shot multi-by-break MB whose output falls after a time τ1 determined by the time constant of the resistor R1 and the capacitor CI when activated is provided at the input stage, and is activated at the falling edge of the multi-high break MB, which is longer than the period t mentioned above. The output of the retrigger one-shot multi-by-flake RMB whose output falls after time τ2 and the input signal are input to an AND circuit AND4, and the output of the tent circuit A N +) becomes the output of the duty ratio discrimination circuit 8. Here, τ is the minimum value of the pulse period passed through, and τ1<τ<τ2.

With this configuration, the output signal shown in ■ is obtained only when an input signal with a period within a certain range arrives, as shown in the first half and the second half of ■ in the fb1 diagram. The component is removed and does not appear as the output signal ■.

Due to the dirt, the detection pulse MP is removed as described above.

As another example, a predetermined reference clock is applied to one input of the ant circuit, and the output shown in FIG. The other detection pulses PN are automatically removed.

(5) Effects of the Invention Since the present invention is constructed and operated as described above, the sliding noise detection pulse and the detection pulse of the magnetic printing part can be completely separated, so that it is possible to completely separate the detection pulse of the magnetic printing part and the presence or absence of the viscosity or magnetic detection output for denomination discrimination. It has a feature that makes it possible to improve the detection accuracy.

[Brief explanation of drawings]

FIG. 1(a) (1) is a diagram of the output waveforms of the magnetic detection means for conventional paper sheets with and without magnetic printing, FIG. 2 is a system diagram of the paper sheet recognition device of the present invention, and FIG. 3 is a waveform explanatory diagram of FIG. 2, FIG. 4 (δ), (bl is a specific configuration diagram of the duty ratio discrimination circuit of FIG. 2. ■... Base 2... Conveying means 3...Paper sheet 4...Magnetic detection means 5...Amplification circuit including a bandpass filter 6...Comparison circuit 8
... Duty ratio discrimination circuit 9 ... Counter circuit 10
・・Karan (・Value comparison circuit 11...Comparison dictionary data I2...Zone division signal generation circuit SI,...
・Threshold level PN...Sliding noise detection pulse
MP...Detection pulse of magnetic printing part Figure 3 Figure 4 Between the fences

Claims (1)

[Claims] Magnetic detection means for discriminating the authenticity of paper sheets conveyed by the conveyance means, and the output of the magnetic detection means is compared with a predetermined darkness value, and values greater than the darkness value are extracted, binarized, and output. a comparison means; a duty ratio discrimination means for not extracting pulses having a predetermined duty ratio from the output of the comparison means;
Paper sheet a, (((
recognition device.