JP5471542B2 - Detection apparatus and program - Google Patents

Description

  The present invention relates to a detection device and a program.

  Patent Document 1 describes a copying machine including a magnetic body detection unit that detects whether or not a magnetic material indicating that copying cannot be performed on a document placed on a platen glass and outputs a detection result as a signal. When the magnetic material detection unit detects a magnetic material attached to the document, the copying operation of the copying machine is prohibited and a message such as an alarm or a copy impossible message is output by voice, an alarm lamp, etc. Has been.

JP 2006-85453 A

  An object of this invention is to provide the detection apparatus and program which can improve the detection precision of the magnetic body which does not change a position with respect to a detection apparatus.

  According to the first aspect of the present invention, when the magnetic field that causes the magnetization reversal occurs when a magnetic field having a strength greater than the positive and negative strengths is applied, the alternating device generates the alternating magnetic field. Three or more detection coils each of which an electric signal is induced by a magnetic field and the magnetization reversal, and switching means for switching the connection relationship between the three or more detection coils, and the same number of alternating currents induced by the alternating magnetic field Based on a control means for controlling the switching means so that two sets of detection coils having opposite phases are connected in series, and an electric signal flowing in a series circuit in which the two sets of detection coils are connected in series, Detecting means for detecting magnetization reversal of the magnetic material.

  A detection device according to a second aspect of the present invention is the detection device according to the first aspect, wherein the combination of the two sets of detection coils is a timing at which one of the timings at which the intensity of the alternating magnetic field is maximum and minimum. Change with.

  A detection device according to a third aspect of the present invention is the detection device according to the first or second aspect, further comprising a magnetic field generating coil provided corresponding to the detection coil, each of which generates the alternating magnetic field. ing.

  According to a fourth aspect of the present invention, there is provided a program that causes a computer to generate an alternating magnetic field that causes the magnetization reversal in a magnetic material that undergoes magnetic reversal when a magnetic field having a magnitude greater than a predetermined positive and negative is applied. The same number of switching means for switching the connection relationship between the alternating magnetic field and the three or more detection coils, each of which induces an electrical signal by the magnetization reversal, and the alternating currents induced in the alternating magnetic field are in opposite phases to each other It functions as a control means for controlling so that two sets of detection coils are connected in series.

  According to the first and fourth aspects of the present invention, compared with a case where there is no switching means for switching the connection relationship between three or more detection coils, the magnetic body that does not change its position with respect to the detection device. Detection accuracy can be improved.

According to the second aspect of the present invention, two sets of detections are performed as compared with the case where the combination of the two sets of detection coils is changed at a timing closer to the timing at which the polarity of the alternating magnetic field is reversed to the maximum and minimum. when performing the detection of the magnetization reversal of a magnetic material based on the electric signals flowing in the series circuit connected to the coil in series, it is easy to avoid the entry of switching noise when changing the combination of the sensing coil to the electrical signal .

  According to the invention of claim 3, the strength of the alternating magnetic field applied to each detection coil can be individually adjusted as compared with the case where an alternating magnetic field is applied to each detection coil with one magnetic field generating coil.

It is a perspective view which shows the schematic structure of the detection apparatus which concerns on embodiment. It is a perspective view which shows an example of a structure of the printed wiring board which concerns on embodiment. It is a perspective view which shows the connection state of the one end and other end of the exciting coil and receiving coil which concern on embodiment. It is a block diagram which shows the detailed structure of the detection apparatus which concerns on embodiment. It is a figure for demonstrating the large Barkhausen effect. It is a wave form diagram which shows an example of the pulse current generate | occur | produced by the magnetic body in an alternating magnetic field. It is a wave form diagram which shows an example in the state where the pulse current which generate | occur | produces with the magnetic body in an alternating magnetic field attenuate | damped. It is a circuit diagram which shows the connection relation (1st state) of the four receiving coils which concern on embodiment. It is a circuit diagram which shows the connection relationship (2nd state) of the four receiving coils which concern on embodiment. It is a flowchart which shows the flow of a process of the detection process program which concerns on embodiment. It is a circuit diagram which shows the connection relationship (1st state) of the six receiving coils which concern on another form. It is a circuit diagram which shows the connection relationship (2nd state) of the six receiving coils which concern on another form. It is a circuit diagram which shows the connection relationship (3rd state) of the six receiving coils which concern on another form.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In the following, a case where the image forming apparatus is used for preventing unauthorized copying will be described as an example, but the present invention is not limited to this.

  As shown in FIG. 1, an image forming apparatus 100 includes a platen glass 92 on which a sheet-like article 41 such as a recording sheet to be copied is placed, and a platen cover 94 that covers the platen glass 92 so as to be openable and closable. And.

In the present embodiment, for example, an article 41 that prohibits illegal copying such as important documents is attached with a tag and integrated. The image forming apparatus 100 according to this embodiment, the detection device for detection knowledge the tag attached to the article 41 is provided.

  The detection device includes a printed wiring board 13 on which an excitation coil 11 and a reception coil 12 described later are formed, a control unit 20 that controls the detection operation, a warning lamp 40 that emits light when a tag is detected, It has.

The printed wiring board 13 is fixed to a surface of the platen cover 94 that faces the platen glass 92 . The warning lamp 40 is fixed to the upper surface of the platen cover 94 . The printed wiring board 13 and the warning lamp 40 are connected to the control unit 20. The control unit 20 is connected to an image forming apparatus control unit 96 that controls the operation of the image forming apparatus 100.

  The image forming apparatus control unit 96 controls the operation of the image reading processing unit 98 that performs optical image reading on the article 41 of the sheet material placed on the platen glass 92, and the image reading processing unit 98 reads the image. The operation of the image generation processing unit 99 that prints out the printed image data is controlled.

When copying, in the image forming apparatus 100, an article 41 to be copied is placed on a platen glass 92 , and the article 41 is covered with a platen cover 94 .

The detection device detects whether or not a tag is present on the article 41 placed on the platen glass 92. When the tag is detected, a control signal for prohibiting copying by the image forming apparatus 100 is displayed as an image. While outputting to the forming apparatus control unit 96, the warning lamp 40 is turned on to prevent unauthorized copying.

  FIG. 2 is a diagram showing the configuration of the printed wiring board 13. Note that FIG. 2 shows that the thickness of the printed wiring board 13 is thicker than the actual thickness in order to make it easy to distinguish the surface on which the receiving coil 12 and the exciting coil 11 are formed.

  On the printed wiring board 13, four receiving coils 12 (12A, 12B, 12C, 12D) having the same number of turns and the same winding direction are formed on one surface so as to be adjacent to each other on a plane, and have the same size as the receiving coil 12. At the same position, four exciting coils 11 (11A, 11B, 11C, 11D) are formed on the other surface with the same number of turns and the same winding direction. That is, the receiving coil 12 and the exciting coil 11 are provided in a one-to-one correspondence.

As shown in FIG. 3, the receiving coils 12A, 12B, 12C and 12D have one end (A +, B + , C +, D +) and the other end (A-, B-, C-, D-) of the coil printed on the wiring. It is pulled out of the substrate 13. On the other hand, the exciting coils 11A, 11B, 11C, and 11D have one end and the other end connected in series to other coils in the order of the exciting coils 11A, 11B, 11D, and 11C, and function as one exciting coil 11 as a whole.

  FIG. 4 is a diagram illustrating a detailed configuration of the detection device. In FIG. 4, the excitation coils 11A, 11B, 11C, and 11D are shown as one excitation coil 11 as a whole.

The detection device includes an AC power supply 15 that supplies an AC current for excitation for generating a magnetic field in the excitation coil 11, a switching unit 16 that switches the connection relationship of each reception coil 12, and an analog that is induced in the reception coil 12. A signal processing unit 21 that converts an electrical signal into a digital signal and a controller 22 that detects the presence of a tag based on the converted digital signal are provided.

  The switching unit 16 is provided with two switches 17 and 18 having one circuit and two contacts. The switch 17 includes three contact points 17A, 17B, and 17C, and switches between energization and non-energization between the contact points 17A and 17B and between the contact points 17A and 17C. The switch 18 includes three contacts 18A, 18B, and 18C, and switches between energization and non-energization between the contacts 18A and 18B and between the contacts 18A and 18C.

  Here, the switches 17 and 18 generate noise unnecessary for detection of the magnetic tag such as ringing at the time of switching. In particular, the relay has an infinite open resistance when the switch is open, which causes a large unnecessary noise. For this reason, it is preferable to use a semiconductor switch (analog switch) with less noise than the relay as the switches 17 and 18.

  One end (A +) of the reception coil 12 </ b> A is connected to the signal processing unit 21, and the other end (A−) of the reception coil 12 </ b> A is connected to the contact 17 </ b> A of the switch 17. One end (B +) of the receiving coil 12B is connected in parallel to the contact 17B of the switch 17 and the contact 18B of the switch 18, and the other end (B−) of the receiving coil 12B is connected to the other end (D−) of the receiving coil 12D. The one end (D +) of the receiving coil 12D is connected in parallel to the contact 17C of the switch 17 and the contact 18C of the switch 18. The other end (C−) of the receiving coil 12 </ b> C is connected to the contact 18 </ b> A of the switch 18, and one end (C +) of the receiving coil 12 </ b> C is connected to the signal processing unit 21.

  The AC power supply 15 supplies an AC current to the exciting coil 11 under the control of the controller 22.

  The exciting coil 11 is excited by being supplied with an alternating current from the alternating current power supply 15, and generates an alternating magnetic field in which the magnetic field changes like a sine wave. Thereby, in each receiving coil 12, an alternating current is induced by the alternating magnetic field generated by the exciting coil 11, and when a tag including a magnetic material having a large Barkhausen effect exists in the alternating magnetic field, A pulse current is generated by the inversion.

The signal processing unit 21 amplifies the differential of both-end voltages (signal voltages respectively output from one end of the receiving coil 12A and one end of the receiving coil 12C) and outputs the differential amplification amplifier 31 and the differential amplification amplifier 31. A waveform shaping circuit 32 for shaping the waveform of the output signal, and a band for outputting a signal in a predetermined band corresponding to a pulse current generated by the magnetization reversal of the magnetic material among the signals shaped by the waveform shaping circuit 32 A pass filter (BP F ) 33 and an analog / digital converter (ADC) 34 that converts a signal output from the band pass filter 33 into a digital signal are provided.

  The controller 22 includes a microcomputer, and includes a CPU (Central Processing Unit) 22A, a ROM (Read Only Memory) 22B, a RAM (Random Access Memory) 22C, and a nonvolatile storage unit 22D including a flash memory. The controller 22 determines whether or not the level of the digital signal output from the ADC 34 exceeds a threshold value, or determines whether or not the waveform shape of the digital signal is a waveform shape due to magnetization reversal of the magnetic material by a cross correlation method or the like. The presence / absence of the tag is detected by the determination, and when the tag is detected, the warning lamp 40 is turned on. Further, the controller 22 controls the switching operation of the switches 17 and 18 of the switching unit 16.

  Next, the large Barkhausen effect will be described.

  The large Barkhausen effect is obtained from a BH characteristic shown in FIG. 5A, that is, from a material having a relatively small hysteresis loop and a relatively small coercive force (Hc), for example, Co—Fe—Ni—B—Si. This is a phenomenon in which steep magnetization reversal occurs when an amorphous magnetic material is placed in an alternating magnetic field. A magnetic material having a large Barkhausen effect undergoes magnetization reversal when a magnetic field having a strength greater than the positive and negative strengths is applied. For this reason, when an exciting current is passed through the exciting coil 11 to generate an alternating magnetic field and a tag is placed in the alternating magnetic field, a pulsed current flows through the receiving coil 12 disposed near the tag at the time of magnetization reversal.

  For example, when the alternating magnetic field shown in the upper part of FIG. 5B is generated by the exciting coil, a pulse current as shown in the lower part of FIG.

  However, the current of the receiving coil 12 includes not only this pulse current but also an alternating current induced by an alternating magnetic field. In the present embodiment, in order to cancel the alternating current induced in the receiving coil 12, the receiving coil 12 is connected so that the winding direction is reversed.

As a magnetic material (magnetic material) contained in the tag, generally, a permanent magnet, for example, a rare earth-based neodymium (Nd) -iron (Fe) -boron (B) as a main component, samarium (Sm)- Cobalt (Co) as the main component, Alnico aluminum (Al) -Nickel (Ni) -Cobalt (Co) as the main component, Ferrite-based barium (Ba) or strontium (Sr) and iron oxide There are those mainly composed of (Fe ₂ O ₃ ), soft magnetic materials, oxide soft magnetic materials, and the like. As the magnetic material causing the large Barkhausen effect, it is preferable to use an amorphous magnetic material having a basic composition of Fe—Co—Si or Co—FeNi.

  The shape of the magnetic material is not particularly limited as long as it is suitable for causing the large Barkhausen effect. However, in order to cause the large Barkhausen effect, a length corresponding to the cross-sectional area is required, and thus a linear shape (wire shape) or a strip shape is preferable, and a wire shape is more preferable.

  When the magnetic material is in the form of a wire, it is preferable that the minimum diameter necessary for causing the large Barkhausen effect is 10 μm or more. Further, the maximum diameter is not particularly limited. For example, when a magnetic material is mixed into a recording medium (paper) and integrated with the recording medium (paper), the diameter is suppressed in order to prevent the magnetic material from being exposed on the surface of the recording medium. Depends on the thickness of the recording medium. For example, in the case of a recording medium having a thickness of about 90 μm, it is preferably 60 μm or less, more preferably 50 μm or less.

  The length of the magnetic material is preferably 5 mm or more as the minimum length necessary for causing the large Barkhausen effect. The maximum length of the amorphous magnetic material is not particularly limited so long as it is not exposed from the recording medium when it is contained inside, but is preferably 430 mm or less.

  However, the current of each receiving coil 12 includes not only this pulse current but also an alternating current induced by an alternating magnetic field. Therefore, two of the four receiving coils 12 are differentially connected so that the winding directions are reversed. As a result, the alternating current induced in the receiving coil 12 connected so that the winding direction is reversed has an opposite phase, and the alternating current induced by the alternating magnetic field in the four receiving coils 12 as a whole cancels out.

The detection device supplies AC power to the exciting coil 11 so that the strength of the alternating magnetic field is sufficiently larger than the coercive force (Hc) of the magnetic material in order to reliably cause magnetization reversal in the magnetic material. Therefore, the magnetic body in the alternating magnetic field, as shown in FIG. 6, in relatively close timing to the timing at which the intensity of the alternating magnetic field is positive or negative inversion, the pulse current flows change occurs steep flux density.

  Incidentally, the pulse current generated in the two receiving coils 12 connected in the forward direction in the winding direction and the pulse current generated in the two receiving coils 12 connected in the reverse direction in the winding direction are substantially equal. In this case, as shown in FIG. 7, the pulse current is attenuated by the differential connection, and the tag cannot be detected.

  Therefore, in the detection device according to the present embodiment, the switching unit 16 switches the combination of the reception coils 12 connected to the signal processing unit 21 so that the winding direction is reversed.

  8 and 9 show a combination of the receiving coils 12.

  In FIG. 8, the switch 17 connects the other end (A−) of the receiving coil 12A and one end (B +) of the receiving coil 12B, and the switch 18 connects one end (D +) of the receiving coil 12D and the other end of the receiving coil 12C. (C-) is connected. Thereby, the winding direction of receiving coil 12A, 12B and receiving coil 12C, 12D becomes reverse.

  In FIG. 9, the switch 17 connects the other end (A−) of the receiving coil 12A and one end (D +) of the receiving coil 12D, and the switch 18 connects one end (B +) of the receiving coil 12B and the other end of the receiving coil 12C. (C-) is connected. Thereby, the winding direction of receiving coil 12A, 12D and receiving coil 12B, 12C becomes reverse.

  FIG. 10 shows a flowchart showing a flow of processing of a detection processing program executed by the CPU 22A when the tag 41 is detected by the detection device according to the present embodiment. The program is stored in advance in the ROM 22B.

  In step S10, the AC power supply 15 is controlled to start supplying an alternating current that generates an alternating magnetic field to the exciting coil 11.

  Thereby, the exciting coil 11 generates an alternating magnetic field.

  In the receiving coil 12, an alternating current is induced by the alternating magnetic field generated by the exciting coil 11, and when there is an article 41 with a tag, a pulse current is generated due to the magnetization reversal of the magnetic material.

In step S12, the switching unit 16 is controlled, the switch 17 connects the other end (A−) of the receiving coil 12A and one end (B +) of the receiving coil 12B, and the switch 18 connects one end (D +) of the receiving coil 12D. And the other end (C−) of the receiving coil 12C are switched to the first state. Thereby, each receiving coil 12 becomes a connection relationship as shown in FIG. 8, and the winding directions of the receiving coils 12A and 12B and the receiving coils 12C and 12D are reversed. The alternating currents induced by the alternating magnetic fields in the receiving coils 12A, 12B, 12C, and 12D are canceled out because they are connected so that the winding directions of the receiving coils 12A and 12B and the receiving coils 12C and 12D are reversed. .
In step S14, the presence / absence of a tag is detected based on the digital signal input from the signal processing unit 21, and if a tag is detected, the process proceeds to step S16, and if no tag is detected, the process proceeds to step S18. .

  In step S16, the warning lamp 40 is lit to notify that the tag has been detected.

At step S18, the intensity of the alternating magnetic field is excited by the exciting coil 11 it is determined whether the maximum or minimum, affirmative determination and if it becomes the flow advances to step S20, when a negative determination again The process proceeds to step S14.

In step S20, the switching unit 16 is controlled, the switch 17 connects the other end (A−) of the reception coil 12A and one end (D +) of the reception coil 12D, and the switch 18 connects one end (B +) of the reception coil 12B. ) And the other end (C−) of the receiving coil 12C. As a result, the receiving coils 12 are connected as shown in FIG. 9, and the winding directions of the receiving coils 12A and 12D and the receiving coils 12B and 12C are reversed. The alternating currents induced by the alternating magnetic fields in the receiving coils 12A, 12B, 12C, and 12D are canceled out because they are connected so that the winding directions of the receiving coils 12A and 12D and the receiving coils 12B and 12C are reversed. .
In step S22, the presence / absence of a tag is detected based on the digital signal input from the signal processing unit 21. If a tag is detected, the process proceeds to step S24. If the tag is not detected, the process proceeds to step S26. .

  In step S24, a control signal for prohibiting copying is output, and a warning lamp 40 is lit to notify that a tag has been detected.

  In step S26, it is determined whether or not the intensity of the alternating magnetic field excited from the exciting coil 11 is maximum or minimum. If the determination is affirmative, the process proceeds to step S28. If the determination is negative, the step is performed again. The process proceeds to S22.

  In step S28, it is determined whether or not to end the process. If the determination is affirmative, the process ends. If the determination is negative, the process proceeds to step S12. This detection processing program ends when an operation is received from an operation panel (not shown).

  As a result, in the connection relationship of either FIG. 8 or FIG. 9, the pulse current generated in the two receiving coils 12 connected in the forward direction to the winding direction and the two connected in the reverse direction in the winding direction. Even when the pulse current generated in the receiving coil 12 becomes equal and the tag cannot be detected, the tag can be detected as long as the pulse current does not become equal in the other connection relation.

In the above-described embodiment, the case where the number of receiving coils 12 is four and the winding direction is reversed in a group of two receiving coils 12 is described. However, the present invention is not limited to this. For example, it is assumed that two receiving coils 12 out of four receiving coils 12 are selected and connected to the signal processing unit 21 with the winding directions of the two receiving coils 12 reversed. The combination for selecting one receiving coil 12 may be changed. In this case, it can be realized even when there are three receiving coils 12. Four or more receiving coils 12 may be provided. FIG. 11 to FIG. 13 show an example of a combination when the winding direction of the six receiving coils 12 (12A, 12B, 12C, 12D, 12E, and 12f) is three by three and the winding direction is reversed. Has been.

  Further, the present invention is not limited to the above-described embodiment, and it is needless to say that the present invention can also be applied to a design modified within the scope of the claims.

  In addition, the detection processing program according to the above embodiment may be stored in a storage device such as an HDD or another memory that is stored in advance in the ROM 22B, or a computer-readable storage medium such as a CD-ROM or DVD-ROM. The present invention may be applied to a form provided in a state stored in the network, a form distributed via wired or wireless communication means, and the like.

11 Excitation coil 12 Reception coil 16 Switching unit 17, 18 Switch 22 Controller 22A CPU

Claims (4)

When an alternating magnetic field that causes the magnetization reversal is generated in a magnetic material whose magnetization is reversed when a magnetic field with a magnitude greater than the determined positive and negative is applied, an electrical signal is induced by the alternating magnetic field and the magnetization reversal, respectively. Three or more sensing coils to be
Switching means for switching a connection relationship between the three or more detection coils;
Control means for controlling the switching means so that two sets of detection coils having the same number and alternating currents induced in the alternating magnetic field in opposite phases are connected in series;
Detection means for detecting magnetization reversal of the magnetic material based on an electric signal flowing in a series circuit in which the two sets of detection coils are connected in series;
A detection device comprising: Wherein, the two sets of the combination of the sensing coil, the intensity of the alternating magnetic field is maximum, smallest timing of at least one sensing device of claim 1, wherein the change in timing. The detection device according to claim 1, further comprising a magnetic field generation coil provided corresponding to the detection coil, each generating the alternating magnetic field. Computer
When an alternating magnetic field that causes the magnetization reversal is generated in a magnetic material whose magnetization is reversed when a magnetic field with a magnitude greater than the determined positive and negative is applied, an electrical signal is induced by the alternating magnetic field and the magnetization reversal, respectively. The switching means for switching the connection relationship between the three or more detection coils is configured so that two sets of detection coils having the same number and the alternating currents induced in the alternating magnetic field in opposite phases are connected in series. Control means for controlling,
Program to function as.

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