JP3311671B2 - Magnetic detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a magnetic detection device. More specifically, the present invention relates to a magnetic detection device that detects an object based on a change in magnetic flux according to the magnetic permeability of the object.

[0002]

2. Description of the Related Art In recent years, a magnetic recording medium such as a magnetic card is made to have a high coercive force in order to improve the recording density in magnetic recording, the S / N ratio of a signal, and the reliability of a signal with respect to an external magnetic field. There is a tendency. However, it is difficult to increase the coercive force of all the recording media used at once, and recording media having different coercive forces are used transiently or in the future in a mixed state. For this reason, the magnetic recording device is required to be compatible so that recording media having different coercive forces can be handled.

To cope with such diversification of the coercive force of the recording medium, a magnetic recording apparatus has a magnetic head according to the coercive force of the recording medium in order to obtain the maximum output and the S / N ratio when recording on the recording medium. It is required to change the recording current of the data. For this reason, the magnetic recording device must first identify the coercive force of the recording medium before recording on the recording medium.

By the way, in a cassette tape or the like,
The case or the like is provided with a coercive force identification marking (the presence or absence of a hole in the case, the position of the hole, etc.). Therefore, in a magnetic recording device that handles a cassette tape or the like,
By identifying the coercive force of the cassette tape based on the marking when the medium is inserted, an appropriate recording current can be determined. However, a marking for recognizing a coercive force of a medium is not provided for a magnetic card or the like. For this reason, in the related art, first, a recording current value at which the output is maximized by repeatedly performing recording and reproduction several times with a recording current value corresponding to a coercive force that may be used first, and thereafter, the recording current value is determined. The data is updated with the value. That is, when a recording medium such as a magnetic card which is not provided with a coercive force identification marking is used, the coercive force cannot be immediately identified from the magnetic layer of the recording medium, and the recording and reproducing attempts are repeated several times. This is performed to determine the coercive force of the magnetic medium.

[0005]

However, in the above-described card reader which handles the magnetic card, the coercive force of the magnetic medium is determined by repeating the trial several times, so that the processing time becomes longer and the card transaction becomes longer. It takes a long time. For this reason, there has been a demand for the development of a device capable of detecting the coercive force of a recording medium without repeating several trials.

On the other hand, even when a recording medium having a marking for identifying the coercive force is used, the difference is caused by the difference in the coercive force of the medium, the difference in the thickness of the protective film layer provided on the medium, and the like. The optimum recording current value is slightly different.
Therefore, when the coercive force is identified based on the marking, it is not possible to adjust to such a delicate difference in the value of the optimum recording current, and even in this case, the coercive force of the recording medium is increased by another means. It would be convenient if it could be detected quickly.

Further, even if a magnetic detection device is developed according to the above-mentioned request, if it is not clear whether the output is due to the detection of the recording medium or an error of the device itself, the coercive force of the recording medium is eventually reached. Since detection becomes difficult, it is preferable to provide an adjusting unit for electrically canceling an error caused by the device itself.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a magnetic detector capable of quickly detecting the coercive force of a recording medium and electrically correcting an output signal error.

[0009]

In order to achieve the above object, in the magnetic detecting device according to the present invention, an exciting coil is wound around two main magnetic poles juxtaposed to have a gap on at least one side. In addition, the magnetic flux passing through one of the main magnetic poles of the main magnetic pole is changed by the object to be detected with respect to the other main magnetic pole. An adjusting means for adjusting the magnetic flux is connected, and a change in the differential output of the magnetic flux of the two main magnetic poles is detected by a detection coil.

Due to variations in the winding of the excitation coil around each main pole, variations may occur in the magnetic flux generated at each main pole even when the object to be detected is not detected. However, by adjusting the exciting current and the phase by adjusting means connected to each exciting coil, the magnetic flux generated in each main magnetic pole can be balanced, and the differential of the detecting coil when the object to be detected is not detected. Prevent output.

Further, the magnetic detecting device according to the second aspect of the present invention has the following features.
An excitation coil is wound around each of the main magnetic poles, and the excitation coil is configured so that a closed-loop magnetic flux flows through the main magnetic poles. The adjusting means has at least one of a variable resistor and a variable capacitor.

Therefore, when a variable resistor is provided as the adjusting means, the exciting current applied to the exciting coil can be adjusted by changing the resistance value of the variable resistor. In the case where a variable capacitor is provided as the adjusting means, the phase of the excitation signal applied to the excitation coil can be adjusted by changing the capacitance of the variable capacitor. By adjusting the current or phase of one or both of the excitation signals applied to each excitation coil, the magnetic fluxes generated by the respective excitation coils at the main magnetic pole can be balanced.

[0013] The magnetic detecting device according to the third aspect is characterized in that
The excitation signal applied to each excitation coil of the two main magnetic poles is amplified by one common amplifier, and the amplified excitation signal is supplied to each excitation coil via a separate adjustment circuit having a variable resistor and a variable capacitor. To be applied.

Therefore, the exciting current applied to each exciting coil is adjusted by the variable resistor of the adjusting circuit, and the phase is adjusted by the variable capacitor. Adjustment circuits are individual for each excitation coil, so adjust the variable resistor or variable capacitor for each adjustment circuit or for one of the adjustment circuits, and adjust each variable so that balanced magnetic flux is generated at each main pole. Adjust the excitation signal to the excitation coil. Also, since the excitation signal applied to each excitation coil is amplified by one common amplifier, the number of parts can be reduced as compared with a case where each excitation coil is driven by an individual amplifier.

Further, the magnetic detecting device according to the fourth aspect is characterized in that:
The two exciting coils are connected in series, while the variable resistor and the variable capacitor are respectively connected in parallel to the exciting coils. Since the excitation coils are connected in series, a common excitation signal is applied. Also, since the variable resistor and the variable capacitor are connected in parallel to the excitation coils, the current and phase of the excitation signal applied to each excitation coil can be individually adjusted for each coil, and each excitation coil has its own main pole. Can be balanced.

Further, the magnetic detecting device according to the fifth aspect is characterized in that:
Auxiliary cores are formed at the ends of the two main magnetic poles to assist the formation of a magnetic path by the object to be detected. A detection coil is wound around each of the two main magnetic poles, and a differential output is extracted from the detection coils. It is configured as follows. Therefore, when the object to be detected approaches one of the main magnetic poles, a magnetic flux leaks from the one of the main magnetic poles to the object to be detected through the auxiliary core portion, and the magnetic flux passing through each of the main magnetic poles is disrupted. There is a difference in output.

According to a sixth aspect of the present invention, in the magnetic detecting device, the main magnetic pole and the auxiliary core are made of a high-permeability magnetic material, and the two main magnetic poles are connected on the other side by a connecting part. The auxiliary core portion provided in the portion is formed so as to protrude in a direction opposite to the connecting portion, and a portion between the protruding auxiliary core portions is a winding portion of the excitation coil or the detection coil.

Accordingly, the two main magnetic poles, the connecting portion, and the respective auxiliary core portions have a substantially π shape as a whole. And
When the magnetic flux passing through each main pole forms a closed loop as a whole, the magnetic flux is applied in the order of one main pole → the air gap → the other main pole → the connection part → the one main pole or in the reverse order. Construct a loop. Since the main pole and the auxiliary core are made of a high-permeability magnetic material, the leakage of magnetic flux from the closed loop hardly occurs. By making the portion between each auxiliary core portion of each main pole the winding portion of the excitation coil or the detection coil, it becomes possible to symmetrically wind each coil with respect to both main poles, It becomes easy to balance the magnetic flux that passes.

Further, as in the magnetic detecting device according to the present invention, the object to be detected is a magnetic card, and the magnetic stripe provided on the magnetic card passes through a position where one of the two main magnetic poles acts on one of the main magnetic poles. In this manner, the one main magnetic pole may be attached.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail based on the best mode shown in the drawings.

FIGS. 1 to 3 show a first embodiment of a magnetic detector to which the present invention is applied. In this magnetic detection device, an excitation coil 3 and a detection coil 4 are wound around two main magnetic poles 2 juxtaposed so as to have a gap 1 on at least one side, and a magnetic sensor unit 5 is formed. The magnetic flux passing through one main magnetic pole 2 of the main magnetic poles 2 is transferred to the magnetic detection position of a magnetic recording device such as a card reader by a detection target (magnetic layer such as a magnetic stripe of a magnetic medium such as a magnetic card) 6. And the detection coil 4 detects a change in the differential output of the magnetic flux passing through the two main magnetic poles 2. In the present embodiment, the gap 1 is provided only at one end of each main pole 2, and the other end of each main pole 2 is connected by the connecting portion 8.

At least one end of each of the two main magnetic poles 2 has
An auxiliary core part 7 is formed to assist the formation of a magnetic path by the detection target 6. In the present embodiment, the auxiliary core portions 7 are formed at both ends of the two main magnetic poles 2. Each auxiliary core portion 7 is formed so as to protrude to the opposite side from the connecting portion 8. And
Each of the main magnetic poles 2 and each of the auxiliary core portions 7 are integrally formed of a high-permeability magnetic material.
And the winding part 9 around which the detection coil 4 is wound.

The exciting coil 3 is wound around the winding portions 9 of the respective main magnetic poles 2. The exciting coils 3 are wound in opposite directions, and the magnetic fluxes passing through the main magnetic poles 2 are opposite to each other, so that a closed-loop magnetic flux Φ1 is generated as a whole.

The leads 3a, 3a of the coils 3, 4
The reference numerals 4a are arranged so as to have an equal positional relationship with each main pole 2 so that the magnetic flux passing through each main pole 2 is easily balanced. That is, the main poles 2 are equidistant across the virtual intermediate axis L so as to have a plane-symmetric positional relationship based on a virtual intermediate plane existing equidistant from each main pole 2 or as shown in FIG. When the coils 3 are considered to be disposed in the same direction, the respective coils 3 have a point-symmetrical positional relationship based on the virtual intermediate axis L when viewed from the direction of FIG. 3A (the direction of arrow A in FIG. 3B). ,
Four lead lines 3a and 4a are arranged. By arranging the leads 3a and 4a of the coils 3 and 4 in this manner, the magnetic flux passing through the main magnetic poles 2 can be balanced. However, not necessarily in such a positional relationship,
It is not necessary to arrange the four lead wires 3a, 4a, and the magnetic flux passing through each main magnetic pole 2 may be balanced by a circuit electrically connected to each coil 3, 4. The exciting coil 3 is supplied with an exciting current sufficient to detect the magnetic permeability of the detection target 6 in a region where the high magnetic permeability core members of the main magnetic poles 2 and the auxiliary core portions 7 are not magnetically saturated. Have been.

This magnetic detection device is arranged so that each main magnetic pole 2 is parallel to the plane A through which the object 6 passes.

As shown in FIG. 2, for example, an excitation circuit having adjusting means 41 for adjusting at least one of the excitation current and the excitation phase is connected to each excitation coil 3. That is, the adjusting means 41 has at least one of the variable resistor 42 and the variable capacitor 43. In the present embodiment, both the variable resistor 42 and the variable capacitor 43 are provided. Each excitation coil 3 is connected to an AC signal source 10, and generates an magnetic flux in the two main magnetic poles 2 by applying an excitation signal from the AC signal source 10. The excitation signal is applied to each excitation coil 3 via the amplifier 44 and the adjustment circuit 45. That is, the excitation signal output from the AC signal source 10 is amplified by one common amplifier 44, and the amplified excitation signal is supplied to each excitation coil 3 by an individual adjustment circuit 45 having a variable resistor 42 and a variable capacitor 43. Is applied via the Each excitation coil 3 is connected in series. Further, the variable resistor 42 and the variable capacitor 43 are connected in parallel to the corresponding exciting coils 3 respectively.

Each variable resistor 42 and variable capacitor 43
Is adjusted, for example, so that the magnetic flux generated in each main pole 2 at the final stage of the manufacturing process of the magnetic detection device is balanced.
Now, as shown in FIG. 2, the adjustment circuit 45 on the one excitation coil 3 side is 45 A, and the adjustment circuit 4 on the other excitation coil 3 side is 45 A.
5 is assumed to be 45B, and a case is considered in which the resistance value of the variable resistor 42B of the adjustment circuit 45B is adjusted to decrease. In this case, the current flowing through the variable resistor 42B in the adjustment circuit 45B relatively increases, and the current flowing through the other exciting coil 3 to which the adjustment circuit 45B is connected relatively decreases.
On the other hand, when the adjustment is made so as to increase the resistance value of the variable resistor 42B of the adjustment circuit 45B, the current flowing through the variable resistor 42B in the adjustment circuit 45B relatively decreases, and the current flowing through the other exciting coil 3 becomes relatively small. Increase. Similarly, when the resistance value of the variable resistor 42A of the adjustment circuit 45A on the one excitation coil 3 side is adjusted to decrease, the excitation current applied to the one excitation coil 3 decreases, and the resistance of the variable resistor 42A decreases. When the value is adjusted to increase, the exciting current applied to one exciting coil 3 increases. Further, when the electric capacitance of the variable capacitor 43B of the adjustment circuit 45B was changed, the phase of the excitation signal applied to the other excitation coil 3 was changed, and the electric capacitance of the variable capacitor 43A of the adjustment circuit 45A was changed. In this case, the phase of the excitation signal applied to the other excitation coil 3 changes. Each variable resistor 42A, 42B and variable capacitor 43
The worker who adjusts A and 43B balances the magnetic flux generated by each excitation coil 3 in each main pole 2 so that the output of the detection coil 4 is canceled, in other words, the detection target 6 is detected. The resistances of the variable resistors 42A and 42B and the capacitances of the variable capacitors 43A and 43B are adjusted so that the output of the detection coil 4 does not occur in a state where there is no output.

A circuit shown in FIG. 3, for example, is connected to the detection coil 4 of the magnetic sensor unit 5 of the magnetic detection device. When the detected object 6 does not exist in the vicinity of the magnetic sensor unit 5 and the magnetic fluxes passing through the main magnetic poles 2 are equal by the adjustment of the adjusting means 41, the magnetic fluxes passing through the main magnetic poles 2 are balanced and the detection coil 4 The output does not change. When the detected object 6 approaches the magnetic sensor unit 5 from this state, the magnetic flux Φ2 leaking from one main magnetic pole 2 to the detected object 6 through each auxiliary core unit 7.
Occurs, and the balance of the magnetic flux passing through each main pole 2 is broken.
Since the degree of leakage of the magnetic flux Φ2 changes depending on the magnetic permeability of the detection target 6, the output of the detection coil 4 changes according to the magnitude of the magnetic permeability. After the output of the detection coil 4 is amplified by the amplifier circuit 11, it is half-wave rectified by the detection circuit 12 and the peak hold circuit 13 and subjected to envelope detection. Become. In this case, the order of amplification and detection may be reversed. Since there is a fixed relationship between the magnetic permeability of the detection target 6 and the magnitude of the coercive force of the detection target 6, the output value of the detection coil 4 corresponding to the magnitude of the coercive force should be checked in advance. Thus, the coercive force of the detection target 6 can be identified based on the output of the detection coil 4.

That is, in this magnetic detection device, each excitation coil 3 is wound around a substantially π-shaped high permeability core member so that the magnetic flux Φ1 forms a closed loop, and the detection coil 4 becomes a differential type. It is wound. For this reason, when the detection target 6 approaches the magnetic sensor unit 5, most of the magnetic flux Φ1 forms a closed loop, but the minimum magnetic flux Φ2 depending on the medium permeability of the detection target 6 acts on the detection target 6. . Therefore, a magnetic flux that is large enough to impair the recording data does not act on the detected object 6, and the magnetic sensor unit 5 can be operated even in the data storage area of the detected object 6. That is, the detected object 6
Is the magnetic stripe 1 of the magnetic card 14 shown in FIG.
In the case of 5, the magnetic sensor unit 5 may be opposed to a free area (guard band) 17 between the tracks 16 which are storage areas in the magnetic stripe 15, but may be opposed to the track 16. . Therefore, the degree of freedom of installation of the magnetic sensor unit 5 is improved, and attachment to a card reader or the like becomes easy.

In this magnetic detection device, the magnetic sensor unit 5 is provided at a magnetic detection position where the magnetic sensor unit 5 can face the object 6 to be detected. For example, as shown in FIG.
In the case where the present invention is applied to a card reader 18 that handles the card 4, the magnetic sensor unit 5 is attached to, for example, a magnetic detection position 19 of a card insertion slot of the card reader 18. By attaching the magnetic sensor unit 5 to the magnetic detection position 19 of the card insertion slot, the magnetic stripe 15 of the magnetic card 14 passes through the position where one of the main magnetic poles 2 acts on one of the main magnetic poles 2. Can be detected at the time of insertion, and the subsequent processing such as data updating can be performed quickly.

The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the gist of the present invention. For example, in the above description, the operator manually adjusts the variable resistor 42 and the variable capacitor 43 of the adjustment circuit 45. However, as shown in FIG. 7, for example, a digital potentiometer 51 and a variable capacitance diode (between terminals) are used. Varicap whose capacitance changes by changing the voltage of
The digital potentiometer 51 and the variable capacitance diode 52 may be automatically adjusted by the controller 46 composed of a microcomputer. That is, after the output of the detection coil 4 is amplified by the amplifier 47, the output is sent to the AD converter 49 via the detection diode 48, and the analog signal is converted into a digital signal and supplied to the controller 46. The controller 46 adjusts the digital potentiometer 51 based on the digital signal from the AD converter 49, and adjusts the variable capacitance diode 52 by converting the digital signal into an analog signal by the DA converter 50. The controller 46 executes a predetermined program when, for example, the power supply of the magnetic detection device is turned on, and executes the digital potentiometer 51 and the variable capacitance diode 5.
Adjust 2. That is, since it is considered that the magnetic sensor unit 5 has not detected the detection target 6 immediately after the power supply of the magnetic detection device is turned on, the controller 46 is configured to cancel the output of the detection coil 4 in this case. Each digital potentiometer 51 and variable capacitance diode 52
Control. Thus, the output of the detection coil 4 can be canceled periodically and automatically, and the output of the detection coil 4 can be canceled even when the main magnetic pole 2 and the like are worn.

In the above description, the excitation signal applied to each excitation coil 3 is amplified by one common amplifier 44. However, as shown in FIG. May be amplified by the amplifier 44. That is, an excitation signal is applied to one excitation coil 3 via a variable resistor 42 and an amplifier 44, and an excitation signal is applied to the other excitation coil 3 via a phase adjustment circuit 53 in addition to the variable resistor 42 and the amplifier 44. You may make it apply. The level of the excitation signal can be changed by the variable resistor 42, and the phase of the excitation signal can be changed by the phase adjustment circuit 53. In FIG. 8, the phase adjustment circuit 53 is provided only on the other excitation coil 3 side, but the phase adjustment between the excitation signals is sufficient by changing the phase of the excitation signal on one side, and the increase in the number of parts is suppressed. Can be.

In the above description, the adjusting means 41 is provided with the variable resistor 42 and the variable capacitor 43. However, the adjusting means 41 is provided with only one of the variable resistor 42 and the variable capacitor 43. You may.

In the above description, the adjusting means 41 is connected to each of the two exciting coils 3. However, the adjusting means 41 may be connected to only one of the exciting coils 3.

In the above description, the main magnetic poles 2 are arranged so as to be parallel to the plane A through which the object 6 passes. However, the second embodiment of the magnetic sensor unit 5 shown in FIG. As in the embodiment, each main magnetic pole 2 may be arranged perpendicular to the plane A through which the detection target 6 passes. In this case, the detected object 6 and each main magnetic pole 2
When the respective positional relations are equal, the magnetic flux passing through each main pole 2 is balanced and the output of the detection coil 4 cannot be obtained, and therefore, as shown in FIG.
The magnetic sensor unit 5 is installed at a position that affects only the magnetic flux of
That is, the magnetic sensor unit 5 is installed so that only one main magnetic pole 2 is opposed to the path along which the detection target 6 relatively moves, and when the detection target 6 approaches one main magnetic pole 2, The balance of the magnetic flux passing through each of the main magnetic poles 2 is broken. Alternatively, even when the magnetic sensor unit 5 is installed so that both the main magnetic poles 2 are opposed to the path along which the detection target 6 relatively moves, the detection target 6 that moves relatively does not have one main magnetic pole 2. The magnetic permeability of the detection target 6 is detected at a stage in which only the magnetic flux passing through the main body 2 is affected, that is, in a state where the magnetic fluxes of the two main magnetic poles 2 are not balanced. In this case, the detected object 6 faces both main magnetic poles 2 after the detection of the magnetic permeability. At this time, most of the magnetic flux flowing through each main magnetic pole 2 passes through the detected object 6. Therefore, the magnetic permeability is detected by using a magnetic flux having a strength that does not impair the recorded data, or the magnetic sensor unit 5 is made to face the empty area 17 of the magnetic stripe 15 of the magnetic card 14, for example. You can do it.

In the above description, the auxiliary cores 7 are formed at both ends of each main magnetic pole 2. However, the auxiliary cores 7 need not always be formed at both ends, and one side of each main magnetic pole 2 may be formed. The auxiliary core part 7 may be formed only in the auxiliary core part 7, or the auxiliary core part 7 may be omitted. For example, the third embodiment of the magnetic sensor unit 5 shown in FIG. 10 and the magnetic sensor unit 5 shown in FIG.
As in the fourth embodiment, the auxiliary core portion 7 may be omitted.

Further, in the above description, the exciting coils 3 of the respective main magnetic poles 2 are wound in opposite directions so that the direction of the magnetic flux passing through the respective main magnetic poles 2 is reversed to generate a magnetic flux Φ1 which forms a closed loop. The magnetic sensor unit 5 shown in FIG.
As in the fifth embodiment, the excitation coil 3 of each main magnetic pole 2
May be wound in the same direction so that the magnetic flux passing through each main pole 2 becomes the magnetic flux Φ3 going in one direction. In this case, as the detected object 6 approaches, almost all of the magnetic flux passing through the one main magnetic pole 2 becomes the magnetic flux Φ2 passing through the detected object 6, so that the magnetic flux having a strength that does not impair the recording data is used. The magnetic susceptibility is detected or, for example, the magnetic stripe 1 of the magnetic card 14
5, the magnetic sensor section 5 may be opposed to the empty area 17.

In the above description, one detection coil 4 is wound around two main magnetic poles 2. However, as in the sixth embodiment of the magnetic sensor unit 5 shown in FIG. A detection coil 4 may be wound around each of the magnetic poles 2 to extract a differential output from each detection coil 4.

The seventh sensor of the magnetic sensor unit 5 shown in FIG.
As in the embodiment, the detection coil 4 may be wound so as to include the two main magnetic poles 2.

Further, as in an eighth embodiment shown in FIG. 15, a detection core portion 32 around which a detection coil 4 is wound, and a gap portion 1 sandwiching the detection core portion 32 and having a gap 1 on one side. The magnetic sensor section 5 may be constituted by two excitation core sections 31 which are juxtaposed and each of which is wound with the excitation coil 3. Then, the magnetic sensor unit 5 is installed so that only the magnetic flux passing through one of the two excitation core units 31 of the two excitation core units 31 can be changed by the detection target unit 6.
May be detected by the detection coil 4.

In this case, when the detection target 6 is not inserted, the magnetic fluxes passing through the two excitation cores 31 are balanced and no output is generated in the detection coil 4 wound around the detection core 32. In this state, when the detected object 6 connects the one excitation core part 31 and the detection core part 32 as shown in the figure, a magnetic flux Φ2 flowing from the one excitation core part 31 to the detection core part 32 is generated. For this reason, the balance of the magnetic flux passing through the two excitation core portions 31 is lost, and an output is generated in the detection coil 4. Since the magnitude of the magnetic flux Φ2 leaking from one of the excitation core portions 31 changes according to the magnetic permeability of the detection target 6, the degree of the imbalance in the magnetic flux passing through each of the excitation core portions 31 also changes, and the magnetic permeability and Since there is a certain relationship between holding power,
An output value of the detection coil 4 corresponding to the coercive force of the detection target 6 is obtained. In this embodiment, the magnetic flux Φ2 is generated between the excitation core portions 31 and the core portions 31 and 32 around which the coils 3 and 4 are wound are located on the opposite side to the detection target 6. Since there is a certain amount of mass as a core material, it is difficult to be affected by other external magnetic fields, metal members, magnetic materials, and the like, and the magnetic sensor unit 5 reacts sensitively only to the detection target 6. be able to.

Further, in the above description, one main pole 2
The detection target 6 acts only on the magnetic flux passing through the main magnetic pole 2, but the detection target 6 may operate only on the magnetic flux passing through the other main magnetic pole 2 instead of the one main magnetic pole 2. Of course.

[0043]

EXAMPLE The coercive force of a magnetic card was actually identified by using the magnetic detection device shown in FIG. As magnetic cards, three types of cards having the same coercive force as those actually used in transactions, specifically, coercive forces of 300 and 650
And 2750 (Oe) magnetic card. The output when no magnetic card was detected was also confirmed.
FIG. 16 shows the output of the magnetic sensor unit 5 when no magnetic card is detected, FIG. 17 shows the output of the magnetic sensor unit 5 when a magnetic card having a coercive force of 300 (Oe) is detected, and FIG. FIG. 18 shows the output of the magnetic sensor unit 5 when the (Oe) magnetic card is detected, and the coercive force is 2750 (Oe).
FIG. 19 shows the output of the magnetic sensor unit 5 when the magnetic card shown in e) is detected. 16 to 18, one scale on the vertical axis is 50 mV, whereas FIG.
In 9, one scale on the vertical axis is 20 mV.

As is apparent from FIG.
It was confirmed that by adjusting the excitation signal applied to each of the excitation coils 3 by 1, the differential output in the state where the magnetic card was not detected can be almost canceled. 17 to 19, it was confirmed that the output of the magnetic sensor unit 5 changed according to the coercive force of the magnetic card. That is, it was confirmed that the coercive force of the magnetic card could be identified based on the output of the magnetic sensor unit 5. Although the drive is performed using the excitation current of the sine wave, the drive may be performed using the excitation current of a rectangular wave, a triangular wave, or the like without being limited to the excitation current of the sine wave.

[0045]

As described above, in the magnetic detecting device according to the first aspect, the exciting coil is wound around the two main magnetic poles juxtaposed so as to have a gap on at least one side, and the detection object is used. A magnetic flux passing through one of the main magnetic poles is provided so as to change with respect to the other main magnetic pole.
An adjusting means for adjusting at least one of the exciting current and the exciting phase is connected to each of the exciting coils of the two main magnetic poles, and the differential output change of the magnetic flux of the two main magnetic poles is detected by the detecting coil. When approaching the sensor section, a signal corresponding to the magnetic permeability of the detection target is output from the detection coil. Since the relationship between the output value of the detection coil and the magnetic permeability of the detection target is constant, the magnetic permeability of the detection target can be identified based on the output of the detection coil. That is, the magnetic permeability of the detection target (recording medium) can be quickly detected. For example, when the present magnetic detection device is applied to a magnetic recording device such as a card reader that handles a recording medium having no coercive force identification marking such as a magnetic card such as a credit card, when the recording medium is inserted into the magnetic recording device, The coercive force can be identified. Therefore, data can be recorded immediately with the optimum recording current value, and recording can be updated or the like in a single process, so that the processing time can be greatly reduced. In addition, even when the present magnetic detection device is applied to a magnetic recording device that handles a recording medium having an identification marking in a case or the like, subtle differences such as a difference in media coercive force between manufacturers and a difference in thickness of a protective film layer provided on the medium. Differences can be reflected in the recording current value,
Reliability can be improved. Further, since the main magnetic poles and the core member of the auxiliary core portion can be used in a region where magnetic saturation does not occur, destruction of data already recorded on the recording medium can be prevented, and the installation of the magnetic sensor portion can be prevented. The degree of freedom is improved. In addition, by adjusting the adjusting means, it is possible to perform a correction to balance the magnetic flux generated in each main magnetic pole and cancel the differential output of the detection coil in a state where the detection target is not detected. It is not necessary to dispose of broken products as defective products, which can improve the production yield. Life can be extended.

In the magnetic detecting device according to the second aspect,
An exciting coil is wound around each of the two main magnetic poles, and the exciting coils are configured so that a closed-loop magnetic flux flows through the main magnetic poles. Since only the minimum magnetic flux required for detecting the magnetic permeability acts on the data, it is possible to prevent damage to the already recorded data and maintain the soundness of the data. For this reason, for example, it is possible to install the magnetic sensor unit at a position facing a portion other than the empty region such as the guard band of the magnetic stripe of the magnetic card, and it is possible to further improve the degree of freedom in installing the magnetic sensor unit. I can do it.
Also, since the adjusting means has at least one of a variable resistor and a variable capacitor, when the variable resistor is provided as the adjusting means, the exciting current applied to the exciting coil is adjusted by changing the resistance value of the variable resistor. When a variable capacitor is provided as the adjustment means, the phase of the excitation signal applied to the excitation coil can be adjusted by changing the capacitance of the variable capacitor. As a result, it is possible to balance the magnetic fluxes generated by the respective excitation coils in the main magnetic pole.

In the magnetic detecting device according to the third aspect,
The excitation signal applied to each of the excitation coils of the two main magnetic poles is amplified by one common amplifier, and the amplified excitation signal is supplied to each excitation coil via a separate adjustment circuit having a variable resistor and a variable capacitor. Therefore, the level of the excitation signal applied to each excitation coil can be adjusted by the variable resistor of the adjustment circuit, and the phase can be adjusted by the variable capacitor. Adjustment circuits are individual for each excitation coil, so adjust the variable resistor or variable capacitor for each adjustment circuit or for one of the adjustment circuits, and adjust each variable so that balanced magnetic flux is generated at each main pole. The excitation signal to the excitation coil can be adjusted. Further, since the excitation signal applied to each excitation coil is amplified by one common amplifier, it is possible to suppress an increase in the number of parts.

Further, in the magnetic detecting device according to the fourth aspect,
Since the two excitation coils are connected in series, a common excitation signal can be applied to the two excitation coils. Even if the excitation signal is distorted by the amplifier, this effect is reduced by two.
Can be applied equally to one excitation coil. That is, the influence of the distortion of the amplifier on each excitation coil can be canceled. Therefore, the detection error can be reduced, and the detection accuracy can be improved. Similarly, the change in the operation of the amplifier is also canceled, so that the operation on the detection coil can be suppressed and the operation can be stabilized. In addition, since the variable resistor and the variable capacitor are connected in parallel to the excitation coils, the current and phase of the excitation signal applied to each excitation coil can be individually adjusted for each coil, and each excitation coil has its own main magnetic pole. Can be balanced.

Further, in the magnetic detecting device according to the fifth aspect,
Auxiliary cores are formed at the ends of the two main magnetic poles to assist the formation of a magnetic path by the detected object. A detection coil is wound around each of the two main magnetic poles, and a differential output is output from the detection coil. Since it is configured to be taken out, the magnetic flux for detecting the magnetic permeability of the detection target can be guided to the detection target side by the auxiliary core portion, and the detection sensitivity can be improved.

The main magnetic pole and the auxiliary core are made of a high-permeability magnetic material, the two main magnetic poles are connected on the other side by a connecting part, and both ends of the main magnetic pole are connected. The auxiliary core portion provided in the portion may be formed so as to protrude on the opposite side to the connecting portion, and a portion between the protruding auxiliary core portions may be a winding portion of an excitation coil or a detection coil. The effect can be achieved. In addition, by forming a portion between the auxiliary core portions of the respective main magnetic poles as a winding portion of the excitation coil or the detection coil, it is possible to symmetrically wind each coil with respect to both main magnetic poles. The magnetic flux passing through the magnetic pole can be easily balanced.

Further, in the magnetic detecting device according to the present invention, the object to be detected is a magnetic card, and the magnetic stripe provided on the magnetic card passes through a position acting on one of the two main magnetic poles. Since the one main pole is attached, it is suitable for application to a card reader that handles a magnetic card.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment of a magnetic sensor unit of a magnetic detection device according to the present invention.

FIG. 2 is a circuit diagram showing an excitation circuit connected to an excitation coil of the magnetic detection device according to the present invention.

FIG. 3 is a circuit diagram showing a detection circuit connected to a detection coil of the magnetic detection device of the present invention.

4A and 4B show the arrangement of lead wires of an excitation coil and a detection coil, wherein FIG. 4A is a view of a main pole viewed from a direction along a virtual intermediate axis, and FIG. 4B is a view of a main pole viewed from a direction perpendicular to the virtual intermediate axis. FIG.

FIG. 5 is a plan view showing a magnetic stripe of the magnetic card.

FIG. 6 is a perspective view showing a state in which the magnetic detection device of the present invention is attached to a card reader.

FIG. 7 is a circuit diagram showing another embodiment of the excitation circuit of the magnetic detection device of the present invention.

FIG. 8 is a circuit diagram showing still another embodiment of the excitation circuit of the magnetic detection device of the present invention.

FIG. 9 is a schematic configuration diagram showing a second embodiment of the magnetic sensor unit of the magnetic detection device according to the present invention.

FIG. 10 shows a third example of the magnetic sensor unit of the magnetic detection device according to the present invention.
It is a schematic structure figure showing an embodiment.

FIG. 11 shows a fourth example of the magnetic sensor unit of the magnetic detection device according to the present invention.
It is a schematic structure figure showing an embodiment.

FIG. 12 shows a fifth example of the magnetic sensor unit of the magnetic detection device according to the present invention.
It is a schematic structure figure showing an embodiment.

FIG. 13 shows a sixth example of the magnetic sensor unit of the magnetic detection device according to the present invention.
It is a schematic structure figure showing an embodiment.

FIG. 14 shows a seventh example of the magnetic sensor unit of the magnetic detection device according to the present invention.
It is a schematic structure figure showing an embodiment.

FIG. 15 shows an eighth embodiment of the magnetic sensor unit of the magnetic detection device according to the present invention.
FIG. 2 is a schematic configuration diagram of the magnetic sensor unit according to the embodiment.

FIG. 16 is a diagram illustrating an example of an output signal of a magnetic sensor unit of the magnetic detection device of the present invention, in a state where nothing is detected.

FIG. 17 is a diagram illustrating an example of an output signal of a magnetic sensor unit of the magnetic detection device according to the present invention, in a case where a magnetic card having a coercive force of 300 (Oe) is detected.

FIG. 18 is a diagram illustrating an example of an output signal of a magnetic sensor unit of the magnetic detection device according to the present invention, in a case where a magnetic card having a coercive force of 650 (Oe) is detected.

FIG. 19 is a diagram illustrating an example of an output signal of a magnetic sensor unit of the magnetic detection device according to the present invention, in a case where a magnetic card having a coercive force of 2750 (Oe) is detected.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Air gap part 2 Main magnetic pole 3 Excitation coil 4 Detection coil 5 Magnetic sensor part 6 Detected object 7 Auxiliary core part 8 Connecting part 9 Winding part 19 Magnetic detection position 41 Adjustment means 42 Variable resistance 43 Variable capacitor 45 Adjustment circuit

────────────────────────────────────────────────── ─── Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) G11B 5/02 G01R 33/00-33/26 G01N 27/72-27/90

Claims (7)

(57) [Claims] An exciting coil is wound around two main magnetic poles juxtaposed so as to have a gap on at least one side, and a magnetic flux passing through one main magnetic pole among the main magnetic poles of the other main magnetic pole is detected by an object to be detected. An adjusting means for adjusting at least one of an exciting current and an exciting phase is connected to an exciting coil of each of the two main magnetic poles so as to change with respect to the main magnetic pole, and a differential output of magnetic flux of the two main magnetic poles is provided. A magnetic detection device, wherein a change is detected by a detection coil. 2. An exciting coil is wound around each of the two main magnetic poles, and the exciting coil is configured so that a closed-loop magnetic flux flows through the main magnetic pole. The adjusting means includes at least a variable resistor and a variable capacitor. The magnetic detection device according to claim 1, wherein the magnetic detection device has one of them. 3. An excitation signal applied to each excitation coil of the two main magnetic poles is amplified by one common amplifier, and the amplified excitation signal is provided with a variable resistor and a variable capacitor in each of the excitation coils. 2. The magnetic detection device according to claim 1, wherein the voltage is applied through a separate adjustment circuit. 4. The variable excitation coil according to claim 3, wherein the two excitation coils are connected in series, and the variable resistor and the variable capacitor are respectively connected in parallel to the excitation coils.
The magnetic detection device according to claim 1. 5. An auxiliary core portion is formed at an end of said two main magnetic poles for assisting formation of a magnetic path by said detected body. A detection coil is wound around each of said two main magnetic poles. 5. The magnetic detection device according to claim 1, wherein a differential output is extracted from the detection coil. 6. The main magnetic pole and the auxiliary core portion are made of a high-permeability magnetic material. The two main magnetic poles are connected on the other side by a connecting portion, and the auxiliary magnetic poles provided at both ends of the main magnetic pole are provided. 6. The magnetic device according to claim 5, wherein the core portion is formed so as to protrude in a direction opposite to the connecting portion, and a space between the protruding auxiliary core portions is a winding portion of the excitation coil or the detection coil. Detection device. 7. The object to be detected is a magnetic card, and the one main magnetic pole is attached so that a magnetic stripe provided on the magnetic card passes through a position acting on one of the two main magnetic poles. 7. The method according to claim 1, wherein
The magnetic detection device according to any one of the above.