JPS5975369A - Recognizing method of paper sheet or the like - Google Patents

Abstract

PURPOSE:To make a slice level correspond to magnetic powder content in magnetic ink by determining the slice level of a pulse signal obtained by scanning a pattern formed by magnetic ink, in accordance with the quantity of light of infrared rays which transmits the pattern. CONSTITUTION:Paper sheet, etc. to be inspected 1 run in the direction X, a pattern 4 formed in magnetic ink on the paper sheet etc. 1 is detected as to transmission infrared rays by a transmission infrared ray sensor 2, and its output is amplified and is inputted to a binary-coding circuit 9 through a delaying circuit 6. Subsequently, the pattern 4 passes through on a magnetic sensor 3, and a pulse corresponding to passing of the magnetic powder material particles of the pattern 4 is outputted from the sensor 3, is amplified 7, and is inputted to the circuit 9 through a BPF 8. The circuit 9 slices the output pulse of the BPF8 by a reference level corresponding to the output level of the circuit 6, binary- codes a pulse exceeding the reference level and inputs it to a CPU10. The CPU10 compares an input binary signal with a reference data of a dictionary memory 11, and verifies the validity of the pattern 4.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to a paper sheet recognition method, and more particularly to a magnetic paper sheet recognition method performed by analyzing a pattern formed using magnetic ink.

(b) Background of the Technology In recent years, automatic teller machines and automatic ticket vending machines have become widespread, and with this, automatic banknote discrimination devices have come into widespread use. In these cases, in order to determine whether the inserted banknote is of a predetermined amount and whether it is a legitimately issued banknote, it is necessary to distinguish the denomination and authenticity.

On the other hand, with advances in copying and printing technology, it has become easier to produce counterfeit banknotes that cannot be identified with the naked eye. Therefore, in order to eliminate such counterfeit banknotes, advanced techniques have been introduced in coinage technology to ensure accuracy of identification.

(c) Prior art and problems As a method for identifying paper sheets such as banknotes and other cash vouchers,
It is well known to use minute patterns that are difficult to detect with the naked eye, but there are also other methods that use magnetic patterns or special inks to form optical patterns that cannot be detected with visible light. methods are beginning to be used.

When analyzing a pattern formed using magnetic ink, a magnetic sensor is scanned relative to the pattern surface, and the obtained pulse signal is sliced at a predetermined level to obtain a binary signal. The binary signal is compared with reference data stored in a dictionary to determine the authenticity or denomination of the paper sheet.

However, the content of magnetic powder in the magnetic ink used in this case varies, and the slice level is fixed, especially for patterns formed using magnetic ink with a low content of magnetic powder. If the
There is a risk that low-level pulse signals will continue to be dropped, leading to erroneous identification or discrimination.

Conventionally, in order to prevent such errors, the reference data for the dictionary was created with a high degree of redundancy, but this method made the creation of the dictionary complicated and It had the disadvantage of requiring extra memory functionality.

On the other hand, a so-called floating slice method has been proposed in which the slice level is determined based on the magnitude of the signal pulse, but this method has the disadvantage that the electric circuit system is complicated and expensive.

(d) Object of the Invention In order to solve the above-mentioned conventional drawbacks, the present invention provides a novel method for automatically setting the slice level in accordance with the content of magnetic powder in magnetic ink. purpose.

(e) Structure of the Invention The present invention provides a paper sheet recognition method that is performed by analyzing a pulse signal obtained by scanning a pattern formed using magnetic ink. It is characterized in that it is determined in accordance with the amount of transmitted infrared light.

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

FIG. 1 is a diagram showing the relationship between the intensity of infrared light transmitted through a pattern formed using magnetic ink (horizontal axis) and the output of a magnetic sensor scanned over the pattern (vertical axis),
It can be seen that there is a relatively simple negative correlation between the infrared transmitted light intensity and the magnetic sensor output. That is, as the magnetic powder content in the magnetic ink increases, the magnetic sensor output increases, but the infrared transmitted light intensity decreases.

FIG. 2 is a diagram showing the positional relationship between the paper sheet 1 to be tested, the transmitted infrared light sensor 2, and the magnetic sensor 3. The pattern 4 formed on the leaf 1 using magnetic ink first passes over the transmitted infrared light sensor 2 . At this time, the pattern 4 is irradiated by an infrared light source (not shown), and the infrared light transmitted therethrough is incident on the transmitted infrared light sensor 2.

Thereafter, the pattern 4 passes over the magnetic sensor 3, and a pulse signal is output from the magnetic sensor 3 in response to the passage of the magnetic powder particles forming the pattern 4.

FIG. 3 is a block diagram of a processing circuit for processing the output signal of the magnetic ink transmission infrared light sensor 2 and the output signal of the magnetic sensor 3.

In the figure, the output signal of the transmitted infrared light sensor 2 is amplified by a preamplifier 5 and then input to a delay circuit 6, where a pattern 4 passes through the transmitted infrared light sensor 2 and then reaches the magnetic sensor 3. will be delayed by the amount of time until This corrects the positional deviation of the measurement location due to external light from both doors.

On the other hand, the output signal pulse of the magnetic sensor 3 is
After being amplified, the signal is input to the bandpass filter circuit 8, where it receives low frequency components (such as the excitation DC component flowing to the magnetic sensor 3) and high frequency components (such as noise generated independently of the magnetic powder forming the pattern). is removed, waveform shaped, and input to the binarization circuit 9. The binarization circuit 9 uses the bandpass filter circuit 8 at a reference level corresponding to the output level of the delay circuit 6.
The output signal pulses are sliced, and the signal pulses above the reference level are converted into binary signals.

This binary signal is input to the central processing unit 10 and compared with reference data for each scanning position stored in the dictionary memory 11 to verify the validity of the pattern 4.

In the above embodiment, a case was shown in which pattern 4 is recognized only on one scanning line, but another scanning line passing over the same pattern or a scanning line passing over another pattern is provided, and these scanning lines are recognized. The accuracy of recognition is increased by arranging an infrared transmitted light sensor and a magnetic sensor on the line in the same manner as above, and processing the output of the sensor on each scanning line using the signal processing circuit shown in Figure 3. Needless to say, it can be done.

(g) Effects of the Invention According to the present invention, the reliability of paper sheet recognition can be improved because it is not affected by variations in the magnetic powder content in the magnetic ink.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the relationship between infrared transmitted light intensity and magnetic sensor output for a pattern formed using magnetic ink, and FIGS. 2 and 3 are one implementation of the paper sheet recognition method according to the present invention. FIG. 2 is a diagram illustrating an example, showing a relationship between a test pattern and a sensor arrangement, and a block diagram of a processing circuit for a sensor output signal. FIG. In the figure, 1 is the paper sheet to be tested, 2 is the transmitted infrared light sensor, 3 is the magnetic sensor, 4 is the pattern, 5 and 7 are the preamplifiers, 6 is the delay circuit, 8 is the bandpass filter circuit, and 9 is the binarization The circuit includes a central processing unit 1o and a dictionary memory 11.

Claims (1)

[Claims] In a paper sheet recognition method performed by analyzing a pulse signal obtained by scanning a pattern formed using magnetic ink, the level at which the pulse signal is sliced is determined by the amount of infrared light transmitted through the pattern. Paper sheet recognition method characterized by corresponding determination