JPH10208004A - Data storage tag - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the reliability of data write/read of a data storage tag that utilizes magnetostriction vibrating reeds. SOLUTION: Magnetostriction vibration reeds 5a to 5d and a separator 6 are hermetically sealed between a case body 3 and a cover sheet 4. A ferromagnetic layer 7 is formed on an inner side of the sheet 4 by coating. A magnetic head is accessed to the layer 7 from the surface side of the sheet 4, and a magnetic pattern which separately gives a bias magnetic field to each reed 5a to 5d is written. Sheet material that has fluff is used for the separator 6, and it prevents the reeds 5a to 5d from coming into direct contact with the layer 7 and also makes them mechanically and freely vibrate. The layer 7 has 25 to 150μ film thickness and has >=2.5Mx/cm residual magnetization.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data storage tag for storing data by appropriately setting a resonance frequency when a magnetostrictive vibrating piece mechanically vibrates.

[0002]

2. Description of the Related Art According to Japanese Patent Publication No. 7-503061 or U.S. Pat. No. 5,420,569, mechanical vibration generated when a magnetostrictive strip (magnetostrictive vibrating reed) is placed in an alternating magnetic field is electrically encoded. There is known a system for detecting an image. The thin-ribbon-shaped magnetostrictive vibrating reed is uniformly magnetized in the width direction, and has a unique vibration frequency according to its length. When an alternating magnetic field acts on such a magnetostrictive vibrating piece, the magnetostrictive vibrating piece resonates with the alternating magnetic field at its own vibration frequency and mechanically vibrates at the resonance frequency.

[0003] Since the mechanical vibration of the magnetostrictive vibrating reed can be electrically detected by an induction coil, for example, a tag incorporating such a magnetostrictive vibrating reed is attached to each product. By installing a gate in which the generator of the alternating magnetic field and the induction coil are opposed to each other and installed, it is possible to prevent unpaid products from being taken out of the store.

Further, the above publication discloses data storage in a plastic case in which a plurality of magnetostrictive vibrating pieces having different lengths and a bias element for applying a magnetic bias to each magnetostrictive vibrating piece are combined. Tag is described. When an alternating magnetic field is applied to the data storage tag, the frequency is swept from a low frequency side to a high frequency side, for example. The resonator element vibrates at the respective fundamental resonance frequencies and higher-order resonance frequencies. Therefore, information can be reproduced by a combination of spectral frequencies at which vibration peaks appear, and the content of the information can be variously rewritten by a combination of the length of the magnetostrictive vibrating reed and the bias magnetic field pattern given by the bias element.

When a data storage tag is used for such a purpose, each magnetostrictive vibrating reed is housed in a case so as not to be taken out, so that data is rewritten by rewriting a bias magnetic field pattern applied to a bias element. Will be For this reason, a ferromagnetic metal such as magnetic stainless steel, nickel, ferrite, or mild steel is used for the bias element, and this is formed in a strip shape and sealed in a case in a state in which it is close to and almost overlaps the magnetostrictive vibrating reed. I have. The bias element is accessed from outside the case by a magnetic head to change the magnetization pattern so that data can be rewritten.

[0006]

However, in the case of using a bias element in the form of a thin metal plate as described above, even if the magnetic head is accessed from outside the case and its magnetization pattern is rewritten, an alternating magnetic field is applied thereto. It was found that when data was read out, the resonance frequency was liable to fluctuate. If the resonance frequency fluctuates, a reduction in vibration output cannot be avoided under the original resonance frequency set at the time of data writing, and accurate data reproduction becomes difficult.

[0007] The above-mentioned disadvantage is considered to be caused by the fact that it is difficult to completely maintain the parallel flatness in the case because a thin metal plate is used as the bias element. If the parallel flatness of the bias element is not maintained in the case, when the bias element is accessed from outside the case and the magnetization is performed, the gap between the bias element and the magnetic head becomes non-uniform, and the magnetization pattern is weak. The bias magnetic field is unevenly applied to the magnetostrictive resonator element.

Further, in order to always apply a bias magnetic field of a constant pattern to the magnetostrictive vibrating reed using a thin metal plate-like bias element, the bias element is punched into a fixed shape so as not to be displaced in the case. Must be bent or bent. However, as described in, for example, Japanese Patent Publication No. 5-19196, SAE1095 steel, Vicaloy, Lemalloy, Arnochrome, and Krovac provided as a magnetic alloy by Vacuum Schmelz are available as such a bias element. A thin metal plate such as a semi-back (all trade names) is used. However, punching such a hard metal significantly shortens the life of the punching blade, which increases the manufacturing cost.

In order to solve the above-mentioned difficulties, a method of applying a magnetic coating such as ferrite of slurry to a non-magnetic substrate whose flatness is easily controlled and using it as a bias element is also conceivable. However, just applying a magnetic coating with a thickness of about several μm, as is done for example with normal magnetic tapes and magnetic disks, cannot provide a sufficient bias magnetic field to the magnetostrictive vibrating reed,
The fact is that the magnetostrictive vibration output cannot be detected under the set resonance frequency.

As another type of bias element, as described in US Pat. No. 4,727,668, a plastic part serving as a case of a data storage tag is formed by mixing barium ferrite powder and integrally forming the same. . When this method is used, a large amount of barium ferrite powder needs to be mixed with plastic in order to give a bias magnetic field of sufficient strength to the magnetostrictive resonator element.
Then, the fluidity of the plastic is greatly reduced, so that efficient injection molding cannot be performed, which not only increases the cost but also deteriorates the mechanical strength of the case.

SUMMARY OF THE INVENTION The present invention has been made in view of the above background, and has been made to solve the drawbacks of the conventional bias element so that data can be written and read with high reliability.
Moreover, it is an object of the present invention to provide a data storage tag that is advantageous in reducing manufacturing costs.

[0012]

According to the present invention, in order to achieve the above object, in a case comprising a non-magnetic case main body and a cover sheet, a strip-shaped magnetostrictive vibrating piece and a predetermined magnetostrictive vibrating piece are provided. In forming a data storage tag in which a bias element for applying a bias magnetic field of a pattern is sealed, a ferromagnetic layer is applied and formed on an inner surface of a cover sheet, and the ferromagnetic layer is used as a bias element. is there. As the ferromagnetic material layer, a material obtained by mixing a ferromagnetic material powder with a binder is used, and in order to ensure the reliability of data writing / reading, the thickness is preferably in the range of 25 μm to 150 μm. The residual magnetization is preferably set to 2.5 Mx (Maxwell) / cm or more.

The magnetic head is accessed from outside the cover sheet to write and update data on the ferromagnetic layer serving as a bias element. To secure magnetic recording performance at this time, the thickness of the cover sheet is required. From 30μ to 500
In order to obtain sufficient physical strength with this thickness, the cover sheet must be made of polyethylene naphthalate, polyethylene terephthalate, polyaramid, polycarbonate, polyimide, or cellulose triacetate. Good to use. further,
It is convenient to use ultrasonic welding for fixing to the case main body, but it is also possible to fix both using an adhesive instead of ultrasonic welding.

When an alternating magnetic field is applied to mechanically vibrate the thin strip-shaped magnetostrictive vibrating reed, the magnetostrictive vibrating reed enters a gap inside the case and its free vibration is hindered, or the magnetic force is applied to the bias element. It is preferable to use a sheet-like separator made of a non-magnetic material whose surface facing at least the magnetostrictive vibrating piece is between the magnetostrictive vibrating piece and the bias element in order to avoid being attracted to the magnetic head. is there. As the separator, a sheet material having fluff on its surface is advantageous, and the thickness is 10 μm to 10 μm.
When the range is set to 0 μm, it is effective without adversely affecting the magnetic correlation between the bias element and the magnetostrictive resonator element. Alternatively, a flexible sponge-like sheet may be used as a whole.

[0015]

FIG. 1 shows an exploded view of a data storage tag using the present invention. The data storage tag 2 includes a case body 3, a cover sheet 4, four strip-shaped magnetostrictive vibrating reeds 5a to 5d, a separator 6, and a ferromagnetic layer 7 applied on the inner surface side of the cover sheet 4. Have been. The case body 3 is manufactured by injection-molding a plastic material such as polystyrene, for example. As shown in FIG.
And the separator 6 are sealed and accommodated.

The case body 3 may be made of other materials such as polycarbonate, polypropylene, polyolefin, acrylonitrile / butadiene / styrene resin, methacrylic resin, acetal resin, acrylonitrile / styrene resin, polyetherimide, nylon, and chloride. Plastics such as vinylidene resin, ethylene vinyl acetate copolymer, polysulfone, polyvinyl chloride, polyethersulfone, polyethylene, polyamide, polyamideimide, polyphenylene sulfide, polyarylate, polybutylene terephthalate, etc. can be used, and non-magnetic materials can be used. If it is, it is not necessarily limited to only plastic.

A step 9 is formed on the inner surface of the case body 3, and the step 9 is further formed with four recesses 10a to 10d. Magnetostrictive vibrating reed 5 is provided in four recesses 10a to 10d.
After accommodating a to 5d, a sheet-like separator 6 is put thereon, and the cover sheet 4 is fixed with the ferromagnetic layer 7 facing the separator 6. The separator 6 is loosely sandwiched between the step 9 and the cover sheet 4 and can be made of paper having fluff on both sides, for example, Japanese paper, but if it is too soft, it leans against the magnetostrictive vibrating piece. A certain amount of stiffness is required because it can interfere with free vibration.

The separator 6 is made of a non-magnetic material and prevents the magnetostrictive vibrating reeds 5a to 5d from jumping out of the respective recesses 10a to 10d and moving.
5d is prevented from coming into direct contact with the ferromagnetic layer 7. As a result, the magnetostrictive vibrating reeds 5a to 5d are accommodated in the recesses 10a to 10d without being mechanically restrained, and can mechanically vibrate freely.

As a material of the separator 6 having such a function, there is a non-woven fabric or a velvet having a fluff (however, a material which is used for a nap fiber having a certain stiffness). When the separator 6 having fluff is used, the overall thickness is 10 μm to 100 μm and the length of fluff is 1 μm to 100 μm.
A size of about μ is preferred. If the entire thickness is too large, the distance between the magnetostrictive vibrating reeds 5a to 5d and the ferromagnetic layer 7 serving as a bias element becomes too wide, and the ferromagnetic layer 7
, The bias magnetic field does not easily act on the magnetostrictive vibrating pieces 5a to 5d.

When the fluffy separator 6 is used,
It is sufficient that at least the surface facing the magnetostrictive vibrating reeds 5a to 5d has fluff, and the other surface does not necessarily have fluff. In addition, if the magnetostrictive vibrating reeds 5a to 5d are flexible enough not to hinder the vibration, it is possible to use a flexible material as a whole such as a sponge for the separator 6, and of course, it is flexible as a whole and It may have fluff. In addition, a flexible polymer film whose surface is embossed can be used.

As the magnetostrictive vibrating reeds 5a to 5d, known materials having high magnetic permeability can be used. For example, there is an amorphous spin-melt ribbon provided by Allied Signal under the trade name "METGLAS 2826MB" or a crystalline silicon transformer steel. In addition, a magnetostrictive resonator element used for such a purpose is required to have a high electric (magnetic) mechanical coupling coefficient as its magnetic property. The magneto-mechanical coupling coefficient indicates the conversion efficiency between the change in the magnetic field and the magnetostrictive vibration. The larger the magnetostriction constant and the magnetic permeability, the larger the value.

In order to improve the magnetic characteristics of the magnetostrictive resonator element,
For example, an appropriate heat treatment including a magnetic field heat treatment as proposed in Japanese Patent Application No. 8-285463 is added as needed. In the illustrated example, four magnetostrictive vibrating reeds 5a to 5d having different lengths are used, but the number may be three or less or five or more.

In order to apply a predetermined bias magnetic field to each of the magnetostrictive vibrating reeds 5a to 5d, a ferromagnetic layer 7 applied to the inner surface of a non-magnetic cover sheet 4 with a uniform thickness is used. Therefore, the ferromagnetic layer 7 is conceptually shown in FIG.
The writing of the magnetization pattern is performed by the magnetic recording device shown in FIG. When writing the magnetization pattern, the magnetic head 15 is brought into contact with or close to the outer surface of the cover sheet 4, and the magnetic head 15 and the data storage tag 2 are relatively moved in the X and Y directions.

The data storage tag 2 is set on the stage 16 with the cover sheet 4 facing upward. A positioning piece is fixed on the upper surface of the stage 16 so that the set position of the data storage tag 2 does not vary. The stage 16 is moved in the Y direction in the figure via a motor 17 and a lead screw 18 by a well-known guide mechanism. The magnetic head 15 is driven by a well-known guide mechanism.
It moves in the X direction in the figure via the motor 20 and the lead screw 21.

The magnetic head 1 via the head driver 22
5 and a motor driver 2
A microcomputer 25 is used to drive the motors 17 and 20 via 3 and 24. Magnetostrictive vibrating reed 5a
A predetermined magnetic pattern is written on the ferromagnetic layer 7 applied to the inner surface of the cover sheet 4 so that a predetermined magnetic field pattern can be given to each of the layers 5d to 5d.

The magnetization pattern written in the ferromagnetic layer 7 is
As described in Japanese Unexamined Patent Publication No. 7-503061, the length of each of the magnetostrictive vibrating pieces 5a to 5d, the number of harmonics of the fundamental frequency of the magnetostrictive vibration to be detected, or the number of types Can be set appropriately according to the combination of the higher harmonics. For example, a magnetization pattern (corresponding to a waveform pattern in which the three types of harmonics are added with reference to the time axis) so as to resonate by designating any three types of harmonics from nine types of harmonics is set. In this case, even if the orders of the three types of harmonics are the same, if the lengths of the magnetostrictive vibrating reeds 5a to 5d are different, the fundamental frequencies are different, so that the magnetization patterns are naturally different.

In this way, four types of magnetization patterns A to D are set for each of the magnetostrictive vibrating reeds 5a to 5d, and in order to apply a bias magnetic field to each magnetostrictive vibrating reed according to these magnetic patterns, it is necessary to use a strong magnetic field. Of the magnetic layer 7,
The strip-shaped region facing each of the strip-shaped magnetostrictive vibrating reeds 5a to 5d may be magnetized by the A pattern to the D pattern.
After the magnetic head 15 and the stage 16 are set in the standby position at the initial position, when data corresponding to these A patterns to D patterns is inputted by a keyboard, the microcomputer 25 drives the motor 17 via the motor driver 23, and the stage 16 Moves in the Y direction.

In synchronization with the movement of the stage 16 in the Y direction, the microcomputer 25 sends a write signal for magnetizing in the A pattern to the head driver 22, thereby sending the write signal to the magnetostrictive vibrating reed 5 a of the ferromagnetic layer 7. The A-pattern magnetic recording is performed on the facing strip-shaped area. When the magnetic recording of the pattern A is completed, the stage 16 is returned to the initial position, and the magnetic head 15 is moved by one step in the X direction via the motor driver 24 and the motor 20 and is sent to a position facing the magnetostrictive vibrating piece 5b. Can be

Subsequently, the magnetic recording of the B pattern is performed while the stage 16 is moved in the Y direction, whereby the magnetic recording of the B pattern is performed in the band-shaped area of the ferromagnetic layer 7 facing the magnetostrictive vibrating piece 5b. Will be Similarly, the magnetic recording of the C pattern and the D pattern is performed, and the magnetic recording for applying the bias magnetic fields of the A to D patterns to the magnetostrictive vibrating reeds 5 a to 5 d is completed in the ferromagnetic layer 7. Note that these magnetic recording patterns correspond to the magnetostrictive vibrating pieces 5a to 5a.
Various changes can be made in accordance with the length of 5d, the order of harmonics to be detected, or the manner of combination and the number of combinations.

As described above, since the magnetic recording is performed on the ferromagnetic layer 7 by accessing the magnetic head 15 from the outside of the cover sheet 4, the cover sheet 4 is too thick and the magnetic head 15 and the ferromagnetic layer 7 If the distance between them increases, sufficient magnetic recording cannot be performed. If the recording current of the magnetic head 15 is increased in order to cope with this, the ferromagnetic layer 7 needs magnetic recording independently of the A pattern to the D pattern at a small interval, whereas the B pattern has Since the recorded A-pattern is disturbed during magnetic recording, the recording current cannot be made too large. Under these circumstances, the data storage tag 2 of the present invention is specially designed for the cover sheet 4 and the ferromagnetic layer 7.

Since the cover sheet 4 is used not only as a support for the ferromagnetic layer 7 but also as an exterior of the data storage tag 2, it needs to have a mechanical strength. Therefore, the material is polyethylene terephthalate (PET),
A sheet or film of cellulose triacetate (TAC), polyethylene naphthalate (PEN), polyaramid, polycarbonate, polyimide or the like is suitable, and its thickness is desirably 30 μ or more. In addition,
If the thickness is less than 30 μm, the mechanical strength is insufficient, and in addition, curling is likely to occur when the ferromagnetic layer 7 is formed by coating, and handling during the manufacturing process is troublesome. There are some negative effects.

As described above, when magnetic recording is performed on the ferromagnetic layer 7 applied to the inner surface of the cover sheet 4, at least the cover sheet 4 is interposed between the magnetic head and the ferromagnetic layer 7. A gap corresponding to the thickness (spacing loss) occurs, which is not preferable from the viewpoint of general magnetic recording technology. However, in the case of the data storage tag 2 of the present invention, since the magnetization pattern required for the ferromagnetic layer 7 has a relatively long wavelength, if the thickness of the cover sheet 4 is set to 500 μm or less, Magnetic recording without problems is possible. Therefore, when the above-mentioned mechanical strength is also taken into consideration, the thickness of the cover sheet 4 is 30 μm to 500 μm.
And more preferably in the range of 40 μm to 300 μm.

In order to add well-known uses and functions to the plastic material used for the cover sheet 4, silica, alumina, titanium oxide, zinc oxide,
It is also possible to add and mix a fine powder such as antimony oxide, kaolin, carbon black, and graphite as a filler. In addition, by using such a filler together, fine irregularities can be given to the surface of the cover sheet 4, and the handleability of the cover sheet 4 in the application step of the ferromagnetic layer 7 and the like can be improved. it can.

Further, in order to reduce the friction between the magnetic head 15 and the surface of the cover sheet 4 in the magnetic recording step, it is also effective to coat a small amount of a known lubricant on the surface of the cover sheet 4. . In the process of applying the ferromagnetic layer 7 to the cover sheet 4, when the cover sheet 4 is handled in a long roll form, a lubricant may be added to the ferromagnetic layer 7. Good. When the ferromagnetic material layer 7 is wound into a roll after coating, a small amount of the lubricant moves from the ferromagnetic material layer 7 to the surface side of the cover sheet 4, and the same effect is obtained.

The magnetic material suitable for the ferromagnetic layer 7 is γ-Fe
_TwoO_Three, Co-FeO_x, Fe_ThreeO _Four, Metal powder, Ba
-Powdered ferromagnetic materials such as ferrite and chromium dioxide
is there. The size of the magnetic material is 0.05μ to 5μ, especially
Preferably it is 0.3 μm to 2 μm. Multi-magnetic when over 2μ
The number of particles having a domain structure increases and the coercive force decreases. 0.0
If the size becomes smaller than 5μ, productivity will decrease and
In addition, the number of particles exhibiting superparamagnetism increases, and
Down. In addition, two or more of the above six ferromagnetic materials are mixed.
You may use it.

To apply the ferromagnetic layer 7 to the cover sheet 4, the ferromagnetic powder is used in a state of being dispersed in a binder. Examples of the binder include nitrocellulose, polyvinyl chloride resin, modified vinyl chloride resin, phenoxy resin, polyurethane resin, vinyl chloride-vinylidene chloride copolymer, and the like, and these may be used as appropriate. Furthermore, if necessary, a polyisocyanate compound is added,
The solvent resistance and mechanical strength of the ferromagnetic layer 7 can be increased.

The ferromagnetic material powder is kneaded with the above-mentioned binder, solvent and appropriate additive by a known method to form a magnetic material slurry. This magnetic slurry is applied to the cover sheet 4 in the form of a web by a known method,
The ferromagnetic layer 7 is dried if necessary after the magnetic field orientation treatment.
Becomes The magnetic field orientation treatment preferably increases the residual magnetization intensity of the ferromagnetic layer 7. The volume of the ferromagnetic powder contained in the ferromagnetic layer 7 is preferably from 25% by volume to 75% by volume, particularly preferably from 35% by volume to 75% by volume, based on the whole volume including the binder. I understood that.

Further, as can be seen from the examples described later, the residual magnetization of the ferromagnetic layer 7 of the present invention is preferably 2.5 Mx (Maxwell) / cm or more. Γ-Fe ₂ O ₃ was used as the ferromagnetic powder, and its volume ratio was 4
A magnetic slurry of 5% by volume was prepared and applied to the cover sheet 4 so that the film thickness after drying changed in several steps, and the correlation between the film thickness and the remanent magnetization was examined. Was observed. From these results, it was confirmed that the thickness of the ferromagnetic layer 7 was desirably in the range of 25 μm to 150 μm.

The cover sheet 4 coated with the ferromagnetic material layer 7 is cut into a predetermined length, and the outside of the case body 3 is sealed between the cover sheet 4 and the case body 3 so as to seal the magnetostrictive vibrating pieces 5 a to 5 d and the spacer 6. It is fixed to the periphery by ultrasonic welding. At this time, the ferromagnetic layer 7 is interposed between the outer peripheral edge of the case body 3 and the cover sheet 4, but the plastic serving as the binder of the ferromagnetic layer 7 is easily melted by ultrasonic vibration, and Since the outer peripheral edge of the sheet 4 is also melted, these can be firmly integrated.

As described above, when the present invention is used, the cover sheet 4 can be handled as a roll even after the ferromagnetic layer 7 is applied. Then, it becomes possible to manufacture the data storage tag efficiently according to a series of manufacturing lines including a cutting step to a fixed length, a fixing step to the case main body 3 by ultrasonic welding, and a conventional manufacturing cost. It can be suppressed much lower than that.

[0041]

Embodiments Hereinafter, specific embodiments will be described. A 200 μm thick polyethylene terephthalate was used for the cover sheet 4 and a magnetic slurry having the following composition was applied and formed. After the coating, the coating was dried by heating in a DC solenoid, and a magnetic field orientation treatment was performed in the coating direction.

Composition of magnetic slurry 100 parts by weight of γ-Fe ₂ O ₃ (average particle size 0.54 μ, needle ratio 6: 1) Vinyl chloride-vinyl acetate copolymer (copolymerization ratio 9: 1) 14 parts by weight (partially hydrolyzed and contains 2% of vinyl alcohol component) ・ 8 parts by weight of polyurethane resin ・ 5 parts by weight of polyisocyanate compound ・ 0.4 parts by weight of butyl stearate

Using the above magnetic slurry, a sample was prepared in which the thickness of the dried ferromagnetic layer 7 was changed, and the remanent magnetization was measured at the 10th harmonic, which hardly produces an output. It is as shown in Table 1. In the comparative example, a thin metal plate was used as a bias element, and this thin metal plate was manufactured by Vacuum Schmelz Co., Ltd.
0/130 "and the thickness is 50μ.

[0044]

[Table 1]

The other magnetic properties of the sample
The coercive force is 302 Oersted and the squareness ratio of the hysteresis characteristic is 0.77. "10th lowest output value" in Table 1
Uses these samples and comparative examples in combination as a bias element of the shortest magnetostrictive vibrating reed 5d (32 mm), and uses the 10th harmonic output as a relative value (the level at the time of the maximum output of the 2nd harmonic is “ 1000 "and the output level at the time of oscillation" 0 "was set to" 0 ".

As can be seen from the results in Table 1, the remanent magnetization of 2.4 Mx / cm was obtained even in the sample having the smallest film thickness, which is a high value not seen in a general magnetic tape or magnetic disk. is there. However, the 10th-order lowest output value is a small relative value of “49”. Considering that the relative output value fluctuates to about “50” due to the influence of noises such as the environment, the 10th-order minimum output value is preferably “60” or more, and more preferably “70” or more. In this respect, it was found that the sample had a problem in practical use, and an error was likely to occur when writing / reading was repeatedly performed.

On the other hand, it can be seen that the samples 1 to 4 have sufficient performance not only at the value of the residual magnetization but also at the 10th-order lowest output value. In particular, in the sample, the residual magnetization is 8.1 Mx / cm, which is smaller than that of the comparative example, but the 10th lowest output value is “329”, which is larger than that of the comparative example. This indicates that the sample has a higher efficiency in the magnetic recording / reproducing process than the sample using the thin metal plate.

Regarding the data storage tag using the comparative example,
When magnetic recording / reading was repeated 50 times, 1
It was found that the 0th-order lowest output value fluctuated between ± 22 (± 7% of the output). On the other hand, in the sample, the variation of the output value in the same measurement was only ± 13 (± 4% of the output). This is because it is difficult to keep the flatness of the metal sheet completely, and when performing magnetic recording, a plastic lid is interposed between the metal sheet and the magnetic head, and the flatness of the lid and the lid and the metal sheet It is considered that the distance between the magnetic head and the thin metal plate becomes unstable because the gap is not uniform.

Further, using the sample and the comparative example, the latitude (latitude) when the level of the write signal when magnetic recording was performed on each bias element was confirmed. In the comparative example, when recording a magnetization pattern that can be detected for the tenth harmonic with respect to the shortest magnetostrictive resonator element 5d in each bias element, in the comparative example, the optimum recording current level is “265”.
However, if the recording current level fluctuates by about 10% in the higher direction, when the alternating magnetic field is applied for data reproduction, the magnetostrictive vibrating piece 5d A phenomenon that the resonance output of the 10th harmonic is lower than that of other magnetostrictive vibrating reeds appears, and it has been found that the reliability is significantly reduced.

On the other hand, in the case of the sample, the optimum recording current level "300" is -20% to + 50%.
It was confirmed that even if there was a degree of fluctuation, the resonance output of the 10th harmonic of the magnetostrictive vibrating reed 5d could be accurately detected. That is, by applying the present invention, it is possible to secure an appropriate latitude in the recording current level when writing a bias magnetic field into the bias element, which has a great advantage in practical use.

As apparent from the above description, in the data storage tag 2 of the present invention, the ferromagnetic layer 7 in which the bias element for applying the bias magnetic field to the magnetostrictive vibrating reeds 5 a to 5 d is applied to the inner surface of the cover sheet 4. To do it. For this reason, the magnetic head 15 is accessed from the surface side of the cover sheet 4 to the ferromagnetic layer 7, and the occurrence of spacing loss between them is inevitable. However, the gap between the magnetic head 15 and the ferromagnetic layer 7 can be kept constant without variation, and the material and thickness of the cover sheet 4 and the film thickness and remanent magnetization of the ferromagnetic layer 7 are appropriately set. By doing so, an appropriate magnetization pattern can be recorded in the ferromagnetic layer 7, and a stable bias magnetic field can be applied to the magnetostrictive vibrating reeds 5a to 5d.

Further, during the manufacturing process of the data storage tag 2, the cover sheet 4 can be handled in the form of a roll even after the application of the ferromagnetic layer 7, so that the manufacturing process can be easily managed. Further, not only is a bias element unnecessary as a separate component, but also the manufacturing cost of the data storage tag can be significantly reduced by improving the efficiency and automation of the manufacturing process.

Further, by using a sheet having fluff or a sheet having high elasticity for the separator 6 disposed between the magnetostrictive vibrating reeds 5 a to 5 d and the ferromagnetic layer 7, 5d at a predetermined position in the case,
Moreover, it can be stored with little mechanical constraint. According to experiments, as the sheet material used for the separator 6, a nonwoven fabric is most preferable.
Next, Japanese paper (used for lining floppy disks) and ordinary copy paper did not have the expected effect with plastic film.

Although the present invention has been described based on the illustrated embodiment, in practicing the present invention, for example, the number and length of the magnetostrictive vibrating reeds are appropriately determined according to the number of bits of data to be stored. The shape of the main body case 3 and the cover sheet 4 can be changed accordingly.

[0055]

As described above, according to the data storage tag of the present invention, a ferromagnetic material layer is formed on the inner surface side of a cover sheet for enclosing a magnetostrictive vibrating reed between the case body and the cover.
Since the ferromagnetic layer is used as a bias element for applying a predetermined bias magnetic field to the magnetostrictive vibrating reed, during the manufacturing process of the data storage tag, the cover sheet and the bias element must be handled as an integral part. , Which makes it easier to manage the manufacturing process while saving the number of parts.
Significant cost reduction is possible.

Further, as compared with a conventional data storage tag using a thin metal plate as a bias element, the gap between the bias element and the magnetostrictive vibrating reed is kept constant. Can be made constant, and highly reliable data recording and data writing can be performed. And the material and thickness of the cover sheet,
Further, by appropriately setting the thickness of the ferromagnetic layer and the remanent magnetization intensity, the mechanical strength of the data storage tag can be sufficiently ensured, and at the same time, the output level at the time of data reading can be sufficiently increased. .

Further, by using a sheet having a fluff or a sponge-like sheet as a sheet material disposed as a separator between the magnetostrictive vibrating reed and the ferromagnetic layer, free vibration of the magnetostrictive vibrating reed is restrained. This can be stored in a predetermined position in the case without performing, and this is effective in improving the reliability of data reading.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a data storage tag using the present invention.

FIG. 2 is a sectional view of a main part of the data storage tag shown in FIG. 1;

FIG. 3 is a schematic diagram of a magnetic recording device.

[Explanation of symbols]

 2 Data storage tag 3 Case body 4 Cover sheet 5a-5d Magnetostrictive vibrating reed 6 Separator 7 Ferromagnetic layer

Claims (8)

[Claims] 1. A case main body made of a non-magnetic material, a strip-shaped magnetostrictive vibrating reed positioned and housed at a predetermined position of the case main body, and arranged close to the magnetostrictive vibrating reed so as to overlap the magnetostrictive vibrating reed. A data storage tag comprising a bias element for applying a bias magnetic field having a predetermined pattern to the vibrating reed, and a cover sheet made of a non-magnetic material for sealing the magnetostrictive vibrating reed and the bias element between a case body. The data storage tag, wherein the bias element is a ferromagnetic layer applied to an inner surface of the cover sheet. 2. The ferromagnetic layer is a layer obtained by mixing a ferromagnetic powder and a binder, and has a thickness of 25 μm to 150 μm.
2. The data storage tag according to claim 1, wherein the value is μ. 3. The data storage tag according to claim 1, wherein the ferromagnetic layer has a residual magnetization of 2.5 Mx / cm or more. 4. The cover sheet is made of polyethylene terephthalate, polyethylene naphthalate, polyaramid,
4. The data storage tag according to claim 2, wherein the data storage tag is made of any one of polycarbonate, polyimide, and cellulose triacetate, and has a thickness of 30 μm to 500 μm. 5. The data storage tag according to claim 1, wherein the cover sheet is fixed to the case body by ultrasonic welding. 6. Between the magnetostrictive vibrating reed and the ferromagnetic layer,
2. The data storage tag according to claim 1, wherein a sheet-like separator made of a nonmagnetic material whose surface facing at least the magnetostrictive vibrating piece is made of a soft non-magnetic material is enclosed. 7. The separator has a thickness of 10 to 100 μm.
7. The data storage tag according to claim 6, wherein the data storage tag has fluff at least on a surface facing the magnetostrictive vibrating piece. 8. The data storage tag according to claim 6, wherein the separator is a flexible sponge-like sheet as a whole.