JP7115919B2 - MAGNETIC DETECTION DEVICE AND MAGNETIC DETECTION METHOD - Google Patents

Description

The present invention relates to a magnetic detection device and a magnetic detection method. More specifically, the present invention relates to a magnetic detection device and a magnetic detection method suitable for detecting the magnetism of printed matter held on the peripheral surface of a rotating metal drum.

2. Description of the Related Art Conventionally, an inspection machine is known that, when printing paper sheets such as bills, arranges a plurality of small pieces and prints them on a large sheet, and inspects the printed large sheet.

In addition, paper sheets such as banknotes are printed with magnetic information using magnetic ink containing magnetic materials to prevent counterfeiting. need to inspect.

Since the magnetic information printed on the printed matter cannot be seen with the naked eye, a magnetic sensor that detects magnetism is generally used for the inspection, and the magnetic information is acquired by the magnetic sensor. In order to stably and accurately inspect magnetic information, it is necessary to reduce noise in magnetic detection by a magnetic sensor.

A first embodiment of Patent Document 1 discloses a magnetic information detection device for detecting magnetic information of a medium, and stores magnetic information about a conveying belt as a noise component in a state in which the medium is not conveyed in advance. A technique is disclosed for reducing noise in magnetic information by subtracting stored noise components from the magnetic information of a medium being conveyed by a conveying belt.

Japanese Patent Application Laid-Open No. 2001-266205

However, since drum bodies such as transport cylinders of printing presses for printing large sheets are formed using conductive materials (electrical conductors, usually metals), magnetic information printed by the printing press is detected by magnetic sensors. An eddy current is generated at the time of inspection, and a magnetic field caused by the eddy current, that is, an induced magnetic field is generated as noise, and a stable magnetic inspection cannot be performed. Further, since the intensity of the induced magnetic field increases as the rotation speed of the drum increases, scratches on the drum itself and scratches on the surface of the drum, such as dents, are clearly detected. Resin drums have poor processing accuracy and a large thermal expansion coefficient, so they are not suitable for large sheet inspection drum bodies that require dimensional accuracy.

In addition, it is preferable that the inspection of magnetic ink printing on large sheets is carried out in-line by incorporating it into the printing press for large sheets. Since the conveying speed is increased according to the situation, the magnetic inspection of large sheets requires a means that can cope with changes in the printing speed, that is, the conveying speed of the large sheet.

On the other hand, in the magnetic information detection device described in the first embodiment of Patent Document 1, only the magnetic information related to the magnetic dust adhering to the conveying belt can be deleted from the stored noise components. In other words, information that is not synchronized with medium transportation (belt movement) cannot be deleted. As described above, in the case of magnetic inspection of large sheets, since a drum containing a conductive material is used, induced magnetic field noise is detected. becomes asynchronous background noise. Therefore, the technique described in the first embodiment of Patent Document 1 cannot deal with induced magnetic field noise caused by the drum body.

The present invention has been made in view of the above-mentioned current situation, and provides a magnetic detection device and a magnetic detection method capable of stably and highly accurately detecting magnetic information on a printed matter conveyed by a metal drum. It is intended to provide

The present invention is a magnetic detection device for detecting the magnetism of printed matter, comprising: a metal drum body that holds the printed matter on its peripheral surface and rotates; and an output of the magnetic sensor in a state in which the drum body rotates at the first rotation speed and no printed material is held on the peripheral surface of the drum body is used for the first difference calculation processing. a storage unit for storing reference data; and a first detection of an output of the magnetic sensor in a state in which the drum rotates at the first rotation speed and a printed matter is held on the peripheral surface of the drum. A control unit for calculating magnetic data related to the printed matter held on the drum body by subtracting the first reference data for difference arithmetic processing stored in the storage unit from the first detection data. and.

Further, according to the present invention, in the above-described invention, the storage unit stores the output of the magnetic sensor in a state where the printed material is not held on the peripheral surface of the drum each time the rotation speed of the drum changes. It is characterized in that it is stored as the first difference calculation processing reference data.

Further, according to the present invention, in the above invention, the magnetic sensor detects the induced magnetic field of the drum body together with the magnetism of the printed matter.

Further, according to the present invention, in the above invention, the first reference data for difference calculation processing includes magnetic data relating to the drum body.

Further, according to the present invention, in the above-described invention, the storage unit stores the magnetic field in a state in which the drum body, which does not hold printed matter on its peripheral surface, rotates at a plurality of rotation speeds different from the first rotation speed. A function of the output of the magnetic sensor corresponding to the rotation speed of the drum body calculated based on reference data, which is the output of the sensor, is stored, and the control unit holds the printed material on the peripheral surface based on the function. The output of the magnetic sensor when the drum body that is not rotated at the second rotation speed is calculated as the second difference calculation processing reference data, and the drum body that rotates at the second rotation speed is calculated. The output of the magnetic sensor in a state in which the printed matter is held on the peripheral surface is obtained as second detection data, and the second reference data for difference calculation processing is subtracted from the second detection data, thereby obtaining the drum body. and calculating magnetic data related to the printed matter held in the .

Further, according to the present invention, in the above invention, the storage section stores the reference data.

Further, according to the present invention, in the above invention, the control unit determines whether or not the printed matter has magnetism by comparing the calculated magnetic data relating to the printed matter with the determination reference data.

Further, according to the present invention, in the above invention, the printed matter held by the drum body is a large-sized sheet on which a plurality of small cut surfaces are arranged over a plurality of rows and a plurality of columns, and the control unit controls the calculated large-sized sheet It is characterized in that whether or not one or more small cut surfaces have magnetism is determined by comparing the magnetic data regarding the sheet with the reference data for judgment in units of the small cut surfaces.

Further, according to the present invention, in the above invention, the control unit compares the calculated magnetic data regarding the large sheet with the reference data for determination in units of the small cut surfaces, thereby determining whether each of the small cut surfaces has magnetism. It is characterized by determining whether or not the large sheet has magnetism by comparing the number of small cut surfaces determined to have magnetism with a predetermined threshold value.

Further, according to the present invention, in the above invention, the printed matter held by the drum body is a large-sized sheet on which a plurality of small cut surfaces are arranged over a plurality of rows and a plurality of columns, and the control unit controls the calculated large-sized sheet The magnetic data on the sheet is divided into the small cut surfaces, and the magnetic data on two or more small cut surfaces are averaged.

Further, according to the present invention, in the above invention, the control unit averages magnetic data relating to a plurality of small cut surfaces for the entire large sheet, for each row, or for each column. .

Further, according to the present invention, in the above invention, the control unit determines whether or not the two or more small cut surfaces have magnetism by comparing the averaged magnetic data with reference data for determination. and

The present invention also provides a magnetic detection method for detecting the magnetism of printed matter by means of a magnetic sensor provided opposite to the peripheral surface of a drum body, wherein the drum body rotates at a predetermined rotational speed and the drum body rotates at a predetermined rotational speed. a difference calculation processing reference data storing step of storing an output of a magnetic sensor in a state in which no printed material is held on the peripheral surface as difference calculation processing reference data; a detection data acquisition step of acquiring, as detection data, the output of the magnetic sensor in a state where the printed material is held on the peripheral surface of the drum body; and a difference calculation processing step of calculating magnetic data relating to the printed matter held by the body.

Further, according to the present invention, in the above-described invention, the difference calculation processing reference data storing step stores the output detected by the magnetic sensor each time the rotation speed of the drum body changes as the difference calculation processing reference data. and the step of:

According to the magnetic detection device and the magnetic detection method of the present invention, the magnetic information of printed matter conveyed by a metal drum can be stably and highly accurately detected.

FIG. 2 is a schematic plan view showing an example of a large banknote magnetically detected by the magnetic detection device according to Embodiment 1; It is a cross-sectional schematic diagram of the test stand with which the experimental apparatus produced by the present inventors. Fig. 2 shows the result of magnetic detection by a magnetic line sensor unit with a magnetic printing medium placed on the test table shown in Fig. 2. The detected image obtained on the left side and the channel waveform on the broken line in the detected image on the right side. , respectively. FIG. 3 shows how induced magnetic field noise is removed when a magnetic print medium is placed on the test table shown in FIG. 2 and magnetism is detected. 1 is a schematic diagram of a magnetic detection device according to Embodiment 1. FIG. 2 is a schematic plan view of the magnetic line sensor unit according to Embodiment 1. FIG. 1 is a block diagram showing the configuration of a magnetic detection device according to Embodiment 1; FIG. FIG. 4 is a diagram showing an example of control of the rotation speed of the drum body in Embodiment 1; FIG. 10 is a block diagram showing the configuration of a magnetic detection device according to Embodiment 2; FIG. 11 is a block diagram showing the configuration of a magnetic detection device according to Embodiment 3; FIG. 10 is a schematic diagram showing an overview of a magnetic detection method (without determination processing) according to Embodiment 3; FIG. 11 is a block diagram showing another configuration of the magnetic detection device according to Embodiment 3; FIG. 11 is a schematic diagram showing an overview of a magnetic detection method (with determination processing) according to Embodiment 3; 1 is a schematic perspective view of a large banknote printing apparatus; FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of a magnetic detection device and a magnetic detection method according to the present invention will be described below with reference to the drawings.

The printed matter to be the subject of the present invention includes printed matter such as bills (banknotes), checks, gift certificates, bills, forms, securities, card-like media (hereinafter also referred to as small pieces), and small pieces of these. A large-sized printed matter (hereinafter also referred to as a large-sized sheet) on which a plurality of is printed can be applied. In addition, the base material used for the printed matter that is the subject of the present invention is generally paper made from plant fibers, but for the purpose of improving durability, water resistance, security, etc., synthetic fibers are used as materials. A paper sheet or a polymer sheet, which is a synthetic resin sheet, may be used. Banknotes made from polymer sheets are called polymer banknotes. In the following, the invention will be described by taking the apparatus and method for banknotes as an example.

Banknotes are generally printed on large sheets on which multiple banknotes can be printed simultaneously. Before banknotes are completed, there are a process of printing a common pattern on multiple banknotes, a process of inspecting the print quality of the pattern, a process of printing a different serial number for each banknote, and an inspection of the print quality of the serial number. a step of cutting the large-sized sheet into banknotes; and a step of inspecting the cut banknotes (small pieces). The magnetic detection of banknotes according to the present invention will be described below. can be applied to both the process of inspecting the

Further, the pattern printing process and the banknote magnetic detection process according to the present invention may be performed by the same device or may be performed by different devices. Similarly, the serial number printing process and the banknote magnetic detection process according to the present invention may be performed by the same device or may be performed by different devices. For example, it may be performed by a device having a printing unit for printing the pattern or the serial number and a magnetic detection device for detecting the magnetism of the pattern or the serial number. On the other hand, a magnetic detection device without a printing unit may be used.

In the following, the present invention will be described by taking, as an example, a design or serial number printing device for large banknotes, particularly a magnetic detection device for detecting the magnetism of large banknotes, which includes a printing unit and a magnetic detection device.

<Embodiment 1>
The magnetic detection device according to the present embodiment is a magnetic detection device for large banknotes on which a plurality of small pieces (banknotes) are printed vertically and horizontally, and is installed in a device for printing patterns or serial numbers of large banknotes. Then, the magnetic image of the large banknote held on the peripheral surface of the drum body of the design or serial number printing device is acquired and compared with the reference image.

As shown in FIG. 1, the large banknote 110 whose magnetism is detected by the magnetism detecting device according to the present embodiment is a large printed matter (large sheet) on which a plurality of small cut surfaces (banknote surfaces) 111 are printed vertically and horizontally. A design and/or a serial number printed with magnetic ink is printed on each cut surface 111 by a printing device. The serial number is a unique serial number for distinguishing each banknote, and is composed of symbols such as letters and numbers. Each bill is distinguished by this information.

When a visible light image of the large banknote 110 is captured, the visible light image contains a pattern and/or a serial number printed with visible light absorbing ink, and the visible light image allows the misalignment and blurring of the printing. Quality can be checked. However, magnetism cannot be detected in visible light images. Therefore, the magnetic detection device according to this embodiment is configured to be able to acquire a magnetic image of the large banknote 110 .

In this specification, the term "magnetic image" means magnetic data obtained from a medium to be detected by a magnetic sensor, that is, an image based on the output of the magnetic sensor. Further, the term "output of the magnetic sensor" includes not only the output (magnetic data) of the magnetic sensor itself, but also general data (preferably image data) based on the output.

Here, first, the points of this embodiment will be described.

The strength of the induced magnetic field generated between the magnetic sensor and the metal (e.g., aluminum) drum increases as the rotation speed of the drum increases, and becomes steeper at the edge of the groove formed in the drum. Increase. Also, dents and scratches on the surface of the drum body are clearly detected. These are more than 100 times the magnetic signal of the large banknote 110, and have been a problem in the magnetic inspection of the large banknote 110.

The points of this embodiment for solving such problems are as follows.
(1) When the rotation speed of the drum body becomes constant, a magnetic image (offset image) is acquired by the magnetic sensor as reference data for difference calculation processing without conveying the large banknotes 110, and is stored in the storage unit. After that, the large bill 110 is conveyed by the drum rotating at that rotational speed, a magnetic image (detection image) is acquired as detection data by the magnetic sensor, and the difference between this detection image and the previous offset image is calculated. Magnetic data (target image) for the oversize banknote 110 is obtained by processing.
(2) The processing of (1) above is performed for each rotational speed of the drum body (every time the rotational speed changes).
(3) The offset image may be taken in advance if the rotation speed of the drum body is the same.

In the process of (1) above,
Target image (data from which unnecessary background noise has been removed)=Detected image−Offset image Detected image=Magnetic detection signal of large banknote 110+Inductive magnetic field detection signal of drum+Magnetic dust detection signal attached to drum Offset image= The induced magnetic field detection signal of the drum + the magnetic dust detection signal adhering to the drum.

Next, with reference to FIGS. 2 and 3, how the induced magnetic field is generated in the experimental apparatus prepared by the present inventors will be described.

As shown in FIG. 2, the test table 120 used is an aluminum plate 121 (thickness 10 mm) to which an iron screw 122 is fixed, and is placed on the aluminum plate 121, and the two aluminum plates are welded to each other. An aluminum plate 123 (thickness 10 mm) joined at a portion 124 , and a magnetic print medium 125 was placed on the aluminum plate 123 .

The magnetic printing medium 125 used was an experimental sample in which two large and small letters "500" were printed on a piece of paper with magnetic ink. Magnetism was detected by the magnetic line sensor unit while moving horizontally, and a magnetic image was created from the output and used as the detected image.

As a result, as shown in FIG. 3, in the detected image (with the magnetic printing medium), the induced magnetic field noise 126 caused by the edge portion of the aluminum plate 123 is large and clearly detected. The detection signal 127 of the iron screw 122 is also detected. Furthermore, the detection signal 128 of the welded portion 124 of the aluminum plate 123 is also detected, albeit slightly. On the other hand, the detection signal 129 of the character "500" of the magnetic printing medium 125 is also detected, but it is very weak.

Next, FIG. 4 shows how induced magnetic field noise is removed when the magnetic printing medium 125 is placed on the test table 120 and detected.

First, without placing the magnetic printing medium 125 on the test table 120, magnetic detection is performed by the magnetic line sensor while moving the test table 120 horizontally under the magnetic line sensor at the same speed as in the case of the detection image. A magnetic image was created from the output and used as an offset image.

As a result, as shown in FIG. 4, the induced magnetic field noise 126 caused by the edge portion of the aluminum plate 123 is clearly detected in the offset image (without the magnetic printing medium) as in the detection image (with the magnetic printing medium). At the same time, a detection signal 127 of the iron screw 122 was detected, and a detection signal 128 of the welded portion 124 of the aluminum plate 123 was also detected, albeit slightly.

On the other hand, in the target image (difference image) obtained by subtracting the offset image from the detection image and performing amplification processing, the induced magnetic field noise 126 caused by the edge portion of the aluminum plate 123, the detection signal 127 of the iron screw 122, and the detection signal 127 of the aluminum plate 123 However, only the detection signal 129 of the characters "500" on the magnetic printing medium 125 could be clearly detected.

As described above, according to the present embodiment, it is possible to obtain magnetic data related to the large banknotes 110 from which unnecessary back noise (induction magnetic field noise) generated by the rotation of the metal drum body is eliminated, and to Magnetic information can be stably and accurately detected.

The configuration of the magnetic detection device 101 according to this embodiment will be described below.

As shown in FIG. 5, a magnetic detection device 101 according to the present embodiment is arranged to face metallic drum bodies (hereinafter simply referred to as drums) 10, 11 and 12 for conveying large banknotes 110 on the circumferential surface of the drum 11. a trigger 13 arranged at a position inside the drum 11 and facing the magnetic line sensor unit 20 for detecting the head position of the large-sized banknote 110 conveyed by the drum 11; and a rotary encoder 14 connected to.

Each drum 10, 11, 12 has a cylindrical portion made of metal (for example, aluminum), and the surface of the cylindrical portion, that is, the peripheral surface (outer peripheral surface) is formed. A portion of the cylindrical portion in the circumferential direction may be missing. Each of the drums 10, 11 and 12 is provided with a holding mechanism (not shown) for holding the large banknotes 110 on the peripheral surface thereof, and is configured to be able to hold the large banknotes 110 at a predetermined position on the peripheral surface. ing. Each drum 10, 11, 12 is controlled by a magnetic detector 101 so as to rotate at an arbitrary speed.

As shown in FIG. 6, the magnetic line sensor unit 20 includes a plurality of magnetic line sensors 21 arranged in a staggered manner in the main scanning direction (the direction orthogonal to the conveying direction of the large banknotes 110) and a plurality of magnetic line sensors 21. A housing 22 to which the sensor 21 is fixed and a control board 23 provided in the housing 22 for controlling the magnetic line sensor 21 are provided, and the magnetism of the large bill 110 is detected.

The magnetic line sensor units 20 are arranged in a line in the axial direction of the drum 11 . The detection width of the magnetic line sensor unit 20 in the main scanning direction is longer than the width of the peripheral surface of the drum 11 , and detects magnetic information from the magnetic ink printed on the large banknote 110 over the entire surface of the large banknote 110 .

Each magnetic line sensor 21 is a multi-channel sensor having a plurality of magnetic sensor elements arranged in a line in the main scanning direction, and outputs magnetic data acquired by each magnetic sensor element. The magnetic sensor elements included in all the magnetic line sensors 21 are arranged at equal pitches in the main scanning direction.

As shown in FIG. 7, the magnetic detection device 101 includes a magnetic line sensor unit 20 having a plurality of magnetic line sensors 21, a personal computer 40 and a control circuit 50 as a control unit 30, a rotary encoder 14, and a trigger 13. , is equipped with

The control circuit 50 includes a logic device such as an FPGA (Field Programmable Gate Array) and includes a data aggregation circuit 51 .

The data aggregation circuit 51 converts the outputs (magnetic data) of the magnetic line sensors 21 into digital data, aggregates them into one piece of image data for each large banknote 110 , and outputs the image data to the personal computer 40 .

The personal computer 40 includes a speed monitor 41 that monitors the rotation speed of the drum 11 based on the pulse signal from the rotary encoder 14, the pulse signal from the rotary encoder 14, the trigger signal from the trigger 13, and the output from the speed monitor 41. A data acquisition control unit 42 that controls the timing at which each magnetic line sensor 21 acquires magnetic data based on the rotation speed of the drum 11 that has been detected, and an offset image that will be described later as image data output from the data aggregation circuit 51. and a difference calculation unit 44 for performing difference calculation processing and generating a target image.

The storage unit 43 stores data generated from the outputs (magnetic data) of the magnetic line sensors 21 when the drum 11 rotates at a predetermined rotational speed and no large banknotes 110 are held on the peripheral surface of the drum 11. A magnetic image, ie, an offset image, is stored as reference data for difference arithmetic processing. The offset image stored in the storage unit 43 is created based on the magnetic data detected from the reference large-sized banknote appropriately printed with magnetic ink. This reference image is created based on the magnetic data detected by each magnetic line sensor 21 of the magnetic detection device 101 from the viewpoint of effective removal of induced magnetic field noise and efficiency, but is generated by other magnetic sensors. It may be created based on detected magnetic data.

The difference calculation unit 44 generates data generated from the outputs (magnetic data) of the magnetic line sensors 21 when the drum 11 rotates at the predetermined rotational speed and the large banknotes 110 are held on the peripheral surface of the drum 11. The magnetic image, that is, the detected image is input from the data aggregation circuit 51 as detected data. Then, the difference calculation unit 44 performs difference calculation processing for subtracting the offset image stored in the storage unit 43 from the detection image input from the data aggregation circuit 51, and generates and outputs a target image. As described above, the target image is free of unnecessary back noise such as induced magnetic field noise due to the rotation of the drum 11, and is composed of magnetic data relating to the large banknote 110 (almost only the large banknote 110).

Next, the operation of the magnetic detection device 101 according to this embodiment and the processing flow of the magnetic detection method according to this embodiment will be described with reference to FIG.

As shown in FIG. 8, first, the rotational speeds of the drums 10 to 12 are gradually increased to a predetermined rotational speed n1 in a state in which the drums 10 to 12 do not convey the large banknotes 110 (drum acceleration step).

Next, in a state in which no large banknotes 110 are conveyed to the drums 10 to 12 rotating at the rotational speed n1, the magnetic line sensor unit faces the full width of the peripheral surface of the drum 11 in synchronization with the timing of the output pulse of the rotary encoder 14. 20 detects a predetermined number of lines of magnetic data, generates an offset image A based on the output, and stores it in the storage unit 43 (difference calculation processing reference data storage step).

Next, a plurality of large banknotes 110 are sequentially conveyed by the drums 10 to 12 rotating at the rotational speed n1. Each large banknote 110 is conveyed at a predetermined position on the peripheral surface of each drum 10 , 11 , 12 by the holding mechanism of each drum 10 , 11 , 12 . Then, the following processing is performed for each of the large banknotes 110 that are sequentially conveyed. That is, the magnetic line sensor unit 20 outputs predetermined magnetic data in accordance with the timing of the output pulse of the rotary encoder 14 from the timing when the leading position of the large banknote 110 reaches the trigger 13 and the trigger signal from the trigger 13 is received. are detected, and a detection image A is generated based on the output (detection data acquisition step). As a result, the detected image A is always acquired at the same position on the drum 11 . After that, by subtracting the offset image A from the detection image A, a target image A of the large bill 110 held on the drum 11 is generated (difference calculation processing step).

Next, the rotational speeds of the drums 10 to 12 are gradually increased to a predetermined rotational speed n2 while the large banknotes 110 are not conveyed by the drums 10 to 12 (drum acceleration step).

Next, while the drums 10 to 12 rotating at the rotational speed n2 do not convey the large banknotes 110, the magnetic line sensor unit 20 scans the magnetic data for a predetermined number of lines in synchronization with the timing of the output pulse of the rotary encoder 14. is detected, and based on the output, an offset image B is generated and stored in the storage unit 43 (difference calculation processing reference data storage step).

Next, a plurality of large banknotes 110 are sequentially conveyed by the drums 10 to 12 rotating at a rotational speed n2. Each large banknote 110 is conveyed at a predetermined position on the peripheral surface of each drum 10 , 11 , 12 by the holding mechanism of each drum 10 , 11 , 12 . Then, in the same manner as in the case of the rotation speed n1, the following processing is performed for each large banknote 110 that is sequentially conveyed. That is, the magnetic line sensor unit 20 outputs predetermined magnetic data in accordance with the timing of the output pulse of the rotary encoder 14 from the timing when the leading position of the large banknote 110 reaches the trigger 13 and the trigger signal from the trigger 13 is received. are detected, and a detection image B is generated based on the output (detection data acquisition step). After that, by subtracting the offset image B from the detection image B, a target image B of the large bill 110 held on the drum 11 is generated (difference calculation processing step).

After that, the drum acceleration step, the reference data storage step for difference calculation processing, the detection data acquisition step, and the difference calculation processing step are repeated as necessary.

As described above, according to the magnetic detection device 101 and the magnetic detection method according to the present embodiment, unnecessary back noise such as induced magnetic field noise due to the rotation of the drum 11 is detected regardless of the rotation speed of the drum 11. Since the target image from which the .

In addition, the storage unit 43 (difference calculation processing reference data storage step) stores the magnetic line sensor unit 20 in a state where the large banknotes 110 are not held on the peripheral surface of the drum 11 each time the rotational speed of the drum 11 changes. Since the magnetic image (offset image) based on the output of 1 is stored as the reference data for difference calculation processing, the magnetic information printed on the large banknote 110 is stably and at a high level every time the rotation speed of the drum 11 changes. can be detected with precision. In addition, since a more accurate offset image can be obtained than when the offset image is acquired in advance, the magnetic information printed on the large banknote 110 can be detected more stably and with higher accuracy. be able to.

In this way, from the viewpoint of improving the accuracy of the offset image, a plurality of offset images are obtained while the drum 11 is rotating at a constant rotational speed, and an image obtained by averaging these offset images can be used. good.

In the second embodiment of Patent Document 1, in addition to the sensor for magnetic detection of the medium, a noise sensor for detecting only the noise component on the conveyor belt is separately provided along the conveyor belt. describes a magnetic information detection device that removes noise components detected by a noise sensor from magnetic information on a medium containing noise components detected by the sensor. However, with this device, there are cases where noise cannot be removed accurately due to performance discrepancies such as variations in output between the magnetism detection sensor and the noise sensor.

On the other hand, in the present embodiment, the same magnetic line sensor unit 20 performs magnetic data acquisition for offset image creation and magnetic data acquisition for detection image creation. unnecessary background noise can be effectively removed.

<Embodiment 2>
In the present embodiment, features unique to the present embodiment will be mainly described, and detailed descriptions of content that overlaps with the first embodiment will be omitted. Also, in the present embodiment and the first embodiment, members having the same or similar functions are denoted by the same reference numerals, and detailed descriptions of the members are omitted in the present embodiment.

Magnetic ink is effective as a means of preventing counterfeiting of paper sheets such as banknotes, but on the other hand, it is easy for ink to be inserted incorrectly in the process of printing large-sized banknotes, and it is necessary to inspect this. However, large banknotes that use magnetic ink cannot be inspected for print quality with the naked eye under room light, so a special method is required to detect mis-insertion of ink during the manufacturing process. becomes. The present embodiment and a third embodiment described later are suitable for detecting mis-insertion of ink in the manufacturing process of such large banknotes.

As shown in FIG. 9, in the magnetism detection device 102 according to the present embodiment, the personal computer 40 as the control unit 30 further includes a determination processing unit 45 that determines whether or not the large bill 110 is magnetized based on the target image. ing. Further, the storage unit 43 stores a template image as determination reference data representing appropriate patterns and serial numbers to be printed with magnetic ink. The determination processing unit 45 determines whether the large banknote 110 has magnetism by comparing the target image of the large banknote 110 calculated by the difference calculation unit 44 with the template image. As a result, the presence or absence of magnetic printing on the large banknote 110 can be inspected by the magnetic detection device 102 . Specifically, the target image and the template image are matched using a template matching technique, and if there is an area in the target image whose degree of similarity with the template image exceeds a predetermined threshold, the large banknote 110 If it is determined that the magnetic ink has been printed (normal), and there is no area in the target image whose degree of similarity to the template image exceeds a predetermined threshold, the large banknote 110 is not printed with magnetic ink (abnormal). ).

Here, the determination processing unit 45 compares the target image of the large banknote 110 calculated by the difference calculation unit 44 with the template image for each small cut surface 111 (preferably one large banknote). It may be determined whether or not all the small cut surfaces 111) of the bill 110 have magnetism. As a result, the magnetic detection device 102 can inspect whether or not the large banknote 110 is magnetically printed in units of the small cut surfaces 111 .

Further, the determination processing unit 45 determines whether or not each small cut surface 111 has magnetism by comparing the target image of the large banknote 110 calculated by the difference calculation unit 44 with the template image for each small cut surface 111 . In addition, it may be determined whether or not the large banknote 110 has magnetism by comparing the number of small cut surfaces 111 determined to have magnetism with a predetermined threshold value. As a result, when the large banknote 110 is wavy, the distance to the magnetic sensor element differs for each small cut surface 111, and areas where the output level from the magnetic line sensor unit 20 is high and areas where the output level is low coexist within the large banknote 110. Even so, the presence or absence of magnetic printing on the large-sized banknote 110 can be inspected by the magnetic detection device 102 . Specifically, the determination processing unit 45 compares the target image of the large banknote 110 calculated by the difference calculation unit 44 with the template image for each small cut surface 111 by the template matching method described above. It is determined whether or not (large banknotes 110) have magnetism, and the number of small cut surfaces 111 determined to have magnetism is counted. Then, the determination processing unit 45 compares the total number of small cut surfaces 111 determined to have magnetism in one large banknote 110 with a predetermined threshold value, and if the total number exceeds the predetermined threshold value, the large banknote 110 is determined to have been printed with magnetic ink (normal), and if the total number of bills is equal to or less than a predetermined threshold value, it is determined that the large bill 110 has not been printed with magnetic ink (abnormal).

<Embodiment 3>
In the present embodiment, features specific to the present embodiment will be mainly described, and detailed descriptions of the contents overlapping those of the first and second embodiments will be omitted. Further, in the present embodiment and the first and second embodiments, members having the same or similar functions are denoted by the same reference numerals, and detailed descriptions of the members are omitted in the present embodiment.

As shown in FIG. 10, in the magnetic detection device 103 according to this embodiment, the personal computer 40 as the control section 30 has a division processing section 46a and an averaging processing section 46b.

As shown in FIG. 11, the division processing unit 46a divides the target image of the entire large banknote 110 generated by the difference calculation unit 44 into units of small cut surfaces 111, and a magnetic image (hereinafter referred to as a small image) of each small cut surface 111. image).

The averaging processor 46b averages two or more sliced images. As a result, the signal portion caused by the magnetic ink remains mainly, and the noise is reduced. Therefore, the presence or absence of the magnetic printing on the two or more small cut surfaces 111 is inspected more accurately using the averaged image. be able to. Specifically, the averaging processing unit 46b averages two or more small pieces of images generated by the division processing unit 46a to generate and output one magnetic image (hereinafter referred to as the average image).

The averaging processing unit 46b may average a plurality of small cut images for the entire large banknote 110 . As a result, noise is further reduced, so that the presence or absence of magnetic printing on the large banknote 110 can be inspected with higher accuracy using the averaged image. Specifically, the averaging processing unit 46b averages all the small cut images (all small cut images related to one large banknote 110) generated by the division processing unit 46a, and creates one magnetic image (average image ) may be generated and output.

As shown in FIG. 12, in this embodiment, the personal computer 40 as the control unit 30 may further include a determination processing unit 46c. Further, the storage unit 43 may store a template image as determination reference data representing appropriate patterns and serial numbers to be printed with magnetic ink.

As shown in FIG. 13, the determination processing unit 46c compares the average image generated by the averaging processing unit 46b with the template image stored in the storage unit 43 to obtain two or more small cut surfaces 111 (all small cut surfaces). When the cut images are averaged, it is determined whether or not the large banknote 110) has magnetism. As a result, the presence or absence of magnetic printing on two or more small cut surfaces 111 (large banknotes 110 when all the small cut images are averaged) can be inspected more accurately by the magnetic detection device 103 . Specifically, the average image and the template image are matched using a template matching technique, and if there is an area in the average image whose degree of similarity with the template image exceeds a predetermined threshold, two or more small pieces The side 111 (the large banknote 110 when all the small cut images are averaged) is determined to be printed with magnetic ink (normal), and the area whose degree of similarity with the template image exceeds a predetermined threshold is included in the average image. If not, it is determined that two or more small cut surfaces (large banknote 110 when all small cut images are averaged) are not printed with magnetic ink (abnormal).

Further, as shown in FIG. 14, in the printing apparatus for large banknotes, the magnetic ink is not uniformly coated on the plate cylinder 132 due to uneven coating 131a of the magnetic ink on the ink roller 131. It is also envisioned that only certain columns or rows of small cut sides 111 of a large banknote 110 conveyed are not printed. In order to inspect such coating unevenness 131a, the averaging processing unit 46b may average a plurality of small pieces of images for each same row or same column. Specifically, the averaging processing unit 46b averages the sliced images generated by the division processing unit 46a for each row or each column to generate one magnetic image (average image) for each row or each column. You may The magnetic detection device 103 may output an average image of each row or each column as shown in FIG. may be compared with the template image to determine whether each row or column of the cut surface 111 has magnetism.

In the second embodiment described above, the determination processing unit 45 compares the target image of the large banknote 110 calculated by the difference calculation unit 44 with the template image in units of small cut surfaces 111 without dividing the target image in units of small cut surfaces 111. Although the case of determining whether or not one or more small cut surfaces 111 or each of the small cut surfaces 111 has magnetism by using After dividing, it may be determined whether one or more small cut surfaces 111 or each small cut surface 111 has magnetism. Specifically, in this case, the personal computer 40 as the control unit 30 further includes a division processing unit similar to the division processing unit 46a of the third embodiment. The division processing unit divides the target image of the entire large banknote 110 generated by the difference calculation unit 44 into small cut surfaces 111, and creates one or more small cut surfaces 111 or magnetic images (hereinafter referred to as small image). Then, the determination processing unit 45 compares each of the cut images generated by the division processing unit with the template images stored in the storage unit 43 by the above-described template matching method, thereby determining one or more cut surfaces 111 or It is determined whether or not each small cut surface 111 (large banknote 110) has magnetism.

In the first to third embodiments described above, the case where the rotation speed of the drum 11 when acquiring the offset image is the same as the rotation speed of the drum 11 when acquiring the detection image has been described. You may use the offset image interpolated from the offset image obtained. Specifically, a plurality of magnetic images based on the output of the magnetic line sensor unit 20 (hereinafter referred to as a Reference images) are prepared as reference data, and based on these reference images, a function of the magnetic image by the output of the magnetic line sensor unit 20 corresponding to the rotation speed of the drum 11 is calculated, and the calculated function is stored in the storage unit 43. memorize to Note that these reference images may also be stored in the storage unit 43 . In addition, the control unit 30 rotates the drum 11, which does not hold the large banknotes 110 on its peripheral surface, at a predetermined rotation speed (excluding the plurality of predetermined rotation speeds when the reference image is generated) based on the function. A magnetic image (offset image) based on the output of the magnetic line sensor unit 20 at that time is calculated as the reference data for difference arithmetic processing. Then, the magnetic image (detection image) based on the output of the magnetic line sensor unit 20 in a state where the large banknotes 110 are held on the peripheral surface of the drum 11 rotating at the same rotational speed as when the offset image is calculated is generated by the difference calculation unit 44 . is obtained as detection data, and the magnetic data (target image) relating to the large banknote 110 held on the drum 11 is calculated by subtracting the offset image from the detection image. As a result, an offset image can be obtained without actually acquiring magnetic data by the magnetic line sensor unit 20 at any rotation speed of the drum 11 within the range where the function holds. Time for image acquisition can be omitted, and the magnetic detection devices 101 to 103 can be operated more flexibly and efficiently.

Further, in the first to third embodiments, the case where the printed material is the large banknote 110 having a plurality of small cut surfaces 111 arranged vertically and horizontally has been described. Alternatively, the magnetic detection devices 101 to 103 may detect the magnetism of small pieces one by one.

In this case, the printed material may be cut from the magnetically printed large banknote 110, or may be magnetically printed on a small size base material from the beginning.

Further, in the first to third embodiments, the case of processing the magnetic image obtained by imaging the output of the magnetic line sensor unit 20 has been described, but the output of the magnetic line sensor unit 20 may be processed without being imaged. . For example, difference calculation processing may be performed by acquiring reference data for difference calculation processing and detected data from the peak value of each channel of the magnetic line sensor unit 20 .

Further, in the first to third embodiments, the case of using the multi-channel magnetic line sensor unit 20 having a plurality of magnetic line sensors 21 as the magnetic sensor has been described, but the magnetic sensor is only one magnetic line sensor 21. Alternatively, one channel of magnetic data may be output.

Although the embodiments of the present invention have been described above with reference to the drawings, the present invention is not limited to the above embodiments. Moreover, the configuration of each embodiment may be appropriately combined or changed without departing from the gist of the present invention.

INDUSTRIAL APPLICABILITY As described above, the present invention is a technology useful for detecting magnetic information on printed matter conveyed by a metal drum.

10, 11, 12: drum body (drum)
13: Trigger 14: Rotary Encoder 20: Magnetic Line Sensor Unit 21: Magnetic Line Sensor 22: Housing 23: Control Board 30: Control Unit 40: Personal Computer 41: Speed Monitor 42: Data Acquisition Control Unit 43: Storage Unit 44: Difference calculation units 45, 46c: Judgment processing unit 46a: Division processing unit 46b: Averaging processing unit 50: Control circuit 51: Data aggregation circuits 101, 102, 103: Magnetic detection device 110: Large banknote 111: Small cut surface (banknote surface)
120: Test benches 121, 123: Aluminum plate 122: Iron screw 124: Welded portion 125: Magnetic printing medium 126: Induced magnetic field noise 127: Iron screw detection signal 128: Welded portion detection signal 129: Printed with magnetic ink Character "500" detection signal 131: Ink roller 131a: Uneven coating 132: Plate cylinder 133: Impression cylinder

Claims (14)

A magnetic detection device for detecting the magnetism of printed matter,
a metal drum that rotates while holding printed matter on its peripheral surface;
a magnetic sensor that is provided facing the peripheral surface of the drum body and detects the magnetism of the printed matter;
A storage unit that stores the output of the magnetic sensor in a state in which the drum rotates at a first rotation speed and no printed material is held on the peripheral surface of the drum as first difference calculation processing reference data. When,
Acquiring as first detection data the output of the magnetic sensor in a state in which the drum rotates at the first rotation speed and a printed matter is held on the peripheral surface of the drum, a control unit that calculates magnetic data related to the printed matter held on the drum body by subtracting the first reference data for difference calculation processing stored in the storage unit from the detected data. Magnetic detection device. The storage unit stores the output of the magnetic sensor in a state in which no printed material is held on the peripheral surface of the drum as the first reference data for difference arithmetic processing each time the rotation speed of the drum changes. 2. The magnetic detection device according to claim 1, wherein the magnetic detection device stores the data. 3. The magnetic detector according to claim 1, wherein the magnetic sensor detects the induced magnetic field of the drum together with the magnetism of the printed matter. 4. The magnetic detection device according to claim 1, wherein said first reference data for difference calculation processing includes magnetic data relating to said drum body. Based on the reference data, which is the output of the magnetic sensor in a state in which the drum body, which does not hold printed material on its peripheral surface, rotates at a plurality of rotational speeds different from the first rotational speed, the storage unit stores storing a function of the output of the magnetic sensor corresponding to the calculated rotation speed of the drum body;
Based on the function, the control unit uses the output of the magnetic sensor when the drum body, which does not hold printed material on its peripheral surface, rotates at a second rotation speed as second difference calculation processing reference data. In addition to calculating, the output of the magnetic sensor in a state where the printed material is held on the peripheral surface of the drum rotating at the second rotation speed is acquired as second detection data, and from the second detection data 5. The magnetic detecting device according to claim 1, wherein magnetic data relating to said printed matter held on said drum body is calculated by subtracting said second reference data for difference calculation processing. 6. The magnetic detection device according to claim 5, wherein the storage section stores the reference data. 7. The control unit determines whether or not the printed matter has magnetism by comparing the calculated magnetic data relating to the printed matter with reference data for judgment. Magnetic detection device. The printed material held by the drum body is a large-sized sheet on which a plurality of small cut surfaces are arranged over a plurality of rows and columns,
The control unit compares the calculated magnetic data relating to the large sheet with the judgment reference data for each of the small cut surfaces to determine whether or not one or more of the small cut surfaces has magnetism. 8. The magnetic detection device according to claim 7. The control unit compares the calculated magnetic data relating to the large sheet with the reference data for determination in units of the small cut surfaces to determine whether or not each of the small cut surfaces has magnetism. 9. The magnetic detection device according to claim 8, wherein it is determined whether or not the large-sized sheet has magnetism by comparing the number of small cut surfaces determined as such with a predetermined threshold value. The printed material held by the drum body is a large-sized sheet on which a plurality of small cut surfaces are arranged over a plurality of rows and columns,
7. The controller according to any one of claims 1 to 6, wherein the calculated magnetic data relating to the large sheet is divided into units of the small cut surfaces, and the magnetic data relating to two or more small cut surfaces are averaged. A magnetic detection device as described. 11. The magnetic detection device according to claim 10, wherein the control unit averages magnetic data relating to a plurality of small cut surfaces for the entire large sheet, for each row, or for each column. 12. The magnetism according to claim 10, wherein the control unit determines whether or not the two or more small cut surfaces have magnetism by comparing averaged magnetic data with reference data for determination. detection device. A magnetic detection method for detecting the magnetism of a printed matter by a magnetic sensor provided facing the peripheral surface of a metal drum that rotates while holding the printed matter on the peripheral surface,
Difference calculation processing reference data storage for storing, as difference calculation processing reference data, an output of a magnetic sensor in a state in which the drum rotates at a predetermined rotational speed and no printed material is held on the peripheral surface of the drum. a step;
a detection data acquisition step of acquiring, as detection data, the output of the magnetic sensor in a state in which the drum body rotates at the predetermined rotational speed and a printed material is held on the peripheral surface of the drum body;
and a difference calculation processing step of calculating magnetic data related to the printed matter held on the drum body by subtracting the reference data for difference calculation processing from the detection data. The difference calculation processing reference data storage step includes a step of storing the output detected by the magnetic sensor each time the rotation speed of the drum body changes as the difference calculation processing reference data. Item 14. The magnetic detection method according to item 13.

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