JP4308550B2 - Sensing seal, sensing system, and sensing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  This invention is a foodofSensing stickers, sensing systems, and freshness detectionSEIt relates to the sensing method.
[0002]
[Prior art]
Conventionally, with respect to freshness sensing, freshness is detected using reactions of enzymes, dyes, pigments, and the like.
For example, according to Japanese Patent Laid-Open No. 3-282248 (see Patent Document 1), in order to examine the freshness of meat, the subject meat is processed by a heat extraction method or a solvent extraction method, and the resulting gravy is On the one hand, inosinic acid, inosine and hypoxanthine are decomposed by the enzyme, and on the other hand, inosine and hypoxanthine are decomposed by the enzyme, each amount being consumed during the reaction in the reaction tube. A value obtained by measuring the amount of oxygen with an oxygen electrode (enzyme sensor) and dividing the latter by the former becomes the freshness index K value, and the freshness of the subject is determined.
In addition, a management label that displays an environmental temperature that affects freshness has been proposed. That is, according to Japanese Patent Laid-Open No. 2001-41830 (see Patent Document 2), in order to control the temperature of fruits and vegetables and fresh products, it is a temperature indicating material that changes color depending on the temperature, and this color changes depending on the temperature. It can be judged visually. Among these color-changing materials, the irreversible type leaves a thermal history and is suitable for temperature management. This temperature indicating material comprises a basic system composed of an electron donating compound (for example, a leuco dye), an electron accepting compound (for example, a developer) and a reversible material, and a temperature characteristic control agent and a binder resin added thereto. In these color development mechanisms, first, the mixture is heated, and when the reversible material and the temperature characteristic control agent are heated to the melting point or higher, the mixture enters a fluid state, takes in the developer, is rapidly cooled and solidifies. The solidified state is an amorphous state (decolored state) and unstable, and when placed in a measurement environment, phase separation proceeds to a crystalline state. When it becomes the place of reaction with the colorant, and the glass transition temperature becomes higher than the glass transition temperature when exposed to high temperature, the developer separates and begins to diffuse and binds to the leuco dye to form a colored state. In this way, temperature management can be achieved by visually recognizing color development.
[0003]
[Patent Document 1]
JP-A-3-282248
[0004]
[Patent Document 2]
JP 2001-41830 A
[0005]
[Problems to be solved by the invention]
In the above enzyme sensor (oxygen electrode), there are problems that it is necessary to sample from the subject itself, the enzyme is expensive, and the storage management of the enzyme is complicated. Even when the temperature is below the temperature, the developer diffuses little by little, and the color development gradually progresses.For this reason, it is necessary to heat and decolorize it using a device such as a thermal head before use. However, there was a problem that it was difficult to erase completely. In order to solve these problems, it is important that the sensor, the processing device, and the measuring device are easy to handle and inexpensive.
[0006]
  Therefore, the main purpose of this invention isFoodfreshnessTheSensing seals, sensing systems, and low-cost, high-sensitivity and easy-to-detectSEIs to provide a sensing method.
[0007]
[Means for Solving the Problems]
  A sensing seal according to the present invention is a sensing seal having a sealing base material and a magnetic body that generates a magnetic field in the surroundings.Be oxidized inThe magnetic field strength at the seal surfaceDecreaseTo doThe protective layer is temporarily attached to the surface of the sealing substrate to protect the magnetic material and to be peeled off during use.TheDetection of food oxidation by reduction of magnetic field strength by magnetic materialSensing seal.
  In such a sensing seal, the magnetic material may be applied to the surface of the seal substrate.
  Moreover, the magnetic body may be mixed in the inside of a sealing base material.
  These sensing stickers,It is preferable that an adhesive layer is formed on the back surface of the seal substrate.
  Moreover, the sensing system according to the present invention includes the sensing seal according to any of the above,SEAnd a sensing means for sensing a change in magnetic field strength on the surface of the sealing seal.
  In this sensing system,SEThe sensing means is a magnetic impedance sensorWhencan do.
  Also according to the present inventionSEThe sensing method includes a step of attaching the sensing seal according to any of the above to a subject directly or a package containing the subject, or a case containing the subject;SESensing the magnetic field strength of the surface of the sealing seal,SEMethod.
[0008]
  Sensing seal, sensing system andSEIn the sensing method, the magnetic field strength of the seal surface, which varies depending on the environment in which it is placed, is detected, so that the time in which it is placed in that environment is detected.ButMonitored. Therefore, it was placed in that environment,FoodGoodsofFreshness can be easily detected.
[0009]
The above object, other objects, features, and advantages of the present invention will become more apparent from the following detailed description of the embodiments of the present invention with reference to the drawings.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a cross-sectional view showing an example of a freshness sensing seal according to the present invention. A freshness sensing seal 10 shown in FIG. 1 detects the freshness of a fresh food product such as fish, and includes a rectangular seal substrate 12 having a width of 5 mm and a length of 15 mm, for example. The seal substrate 12 is made of, for example, synthetic resin or paper.
[0011]
A magnetic layer 14 is formed on the surface of the seal substrate 12. The magnetic layer 14 is formed by mixing magnetic powder that causes a change in magnetic properties in an environment in which it is placed with the binder and coating the surface of the seal substrate 12.
Examples of the magnetic powder include hard magnetic Sm.₂Fe₁₇N_ThreeMagnet powder and Nd₂Fe₁₄B-based rare earth magnet powder is used. When this magnetic powder comes into contact with oxygen or water, it begins to oxidize and decompose, and the oxidized or decomposed portion is non-magnetic Sm.₂O_ThreeOr Nd₂O_ThreeAnd hard magnetic properties such as saturation magnetization are degraded.
As the binder, for example, a urethane resin is used.
[0012]
On the surface of the magnetic layer 14, a protective sheet 16 that hardly allows oxygen or water to pass through is temporarily attached. As the protective sheet 16, for example, aluminum foil, PVDC (polyvinylidene chloride), MXD-6 (metaxylylene diamine / azibic acid), PVA coated with vinylidene chloride, OPP, PET, ONY, and aluminum are vapor-deposited. A resin sheet such as CPP, PET, ONY, or PET on which silica is vapor-deposited is used. The protective sheet 16 peels the surface of the magnetic layer 14 and is temporarily attached to the peeled surface of the magnetic layer 14 with a re-peelable adhesive.
The protective sheet 16 is for preventing the magnetic powder in the magnetic layer 14 from being oxidized by oxygen in the atmosphere.
[0013]
An adhesive layer 18 is formed on the back surface of the sheet substrate 12. The pressure-sensitive adhesive layer 18 is for bonding the freshness sensing seal 10 to a packaging material or the like of a fresh food product whose freshness is to be detected. In addition, the well-known peeling mount 20 for temporarily protecting the surface of the adhesive layer 18 is temporarily attached.
[0014]
When the freshness sensing seal 10 shown in FIG. 1 is placed in the atmosphere with the protective sheet 16 peeled off, the magnetic powder in the magnetic layer 14 is gradually oxidized. Therefore, the freshness sensing seal 10 shown in FIG. 1 shows the relationship between the time (time) placed in the atmosphere and the amount of decrease in magnetic field strength (%) when the protective sheet 16 is peeled off, as in the graph of FIG. The magnetic field strength decreases with time.
[0015]
Therefore, the freshness sensing seal 10 can monitor the time spent in the environment by detecting the change in the magnetic properties of the magnetic material due to the environment placed.
Therefore, the freshness sensing seal 10 can detect the freshness of, for example, fresh food items placed in the environment.
[0016]
Next, an example in which the freshness of a fish is detected or measured by the freshness sensing system 100 using the freshness sensing seal 10 and the magnetic impedance sensor (Aichi Steel MI chip) 30 will be described with reference to FIG.
[0017]
First, the freshness sensing seal 10 is affixed to the inside of the case C containing fresh food, for example, fish, so that the freshness sensing seal 10 receives the same environmental change as the fish. In this freshness sensing seal 10, magnetic powder is applied to the surface of the seal substrate 12 to form a magnetic layer 14, and the freshness sensing seal 10 is applied to the magnetic powder and the protective sheet 16 is peeled off. At the same time, it starts to come into contact with air and the magnetic powder gradually begins to oxidize.
An adhesive layer 18 is formed on the back surface of the sheet substrate 12. The pressure-sensitive adhesive layer 18 is for bonding the freshness sensing seal 10 to a packaging material or the like of a fresh food product whose freshness is to be detected. In addition, although the well-known peeling mount 20 for protecting the surface is temporarily attached to the surface of the adhesive layer 18, the peeling mount 20 is removed before sticking the freshness sensing seal 10, and an adhesive layer is attached to a subject. Adhere at 18.
The magnetic powder is wrapped in the magnetic layer material (binder), but oxygen gradually passes through the magnetic layer material (binder), so that the oxygen that reaches the magnetic powder contacts the magnetic powder and oxidizes. Begins.
Hard magnetic Sm as magnetic powder₂Fe₁₇N_ThreeRare earth magnet powder and Nd₂Fe₁₄B-based rare earth magnet powder is oxidized from the surface portion of the powder, but the oxidized portion is non-magnetic Sm.₂O_ThreeOr Nd₂O_ThreeAnd the hard magnetic properties are degraded.
[0018]
In detecting or measuring freshness, the strength of the magnetic field appearing on the surface of the freshness sensing seal 10 is measured before applying the freshness sensing seal 10. That is, the detector 32 of the freshness sensing system 100 is put on the surface of the freshness sensing seal 10 and measured with the magnetic impedance sensor 30 to be an initial value.
Thereafter, the freshness sensing seal 10 is affixed, the protective sheet 16 is peeled off, and the magnetic powder is oxidized. However, when it is necessary to know the freshness at a certain time, the magnetic field strength of the surface of the freshness sensing seal 10 is magnetized. By measuring with the impedance sensor 30, the amount of change in the magnetic field intensity based on the change in magnetic characteristics from the initial value can be found. Since the amount of change is proportional to the logarithm of the elapsed time, the elapsed time can be known from the data obtained in advance.
If the magnetic powder of the freshness sensing seal 10 is previously magnetized or magnetized before being measured by the magnetic impedance sensor 30, for example, hard magnetic Sm₂Fe₁₇N_ThreeSince the magnetic field is generated from the powder, the magnetic field intensity can be measured by the magnetic impedance sensor 30.
The magnetic impedance sensor 30 has a detection sensitivity that is 1/1000 of the magnetic field strength (several gauss) equivalent to geomagnetism, and can measure even a weak magnetic field strength. It is a magnetic sensor that can be measured with sensitivity.
[0019]
As described above, the magnetic powder of the freshness sensing seal 10 gradually changes (decreases) in magnetic field strength due to oxidation, which starts by applying the freshness sensing seal 10 and peeling off the protective sheet. This minute magnetic field strengthchangeCan be measured with a highly sensitive magnetic impedance sensor to know the length of time in the atmosphere. That elapsed time directly represents freshness.
[0020]
As a simple sensing system, a system in which a magnetic fluid film seal is attached to the front surface of the seal and the magnetic flux (magnetic field strength) generated from the sensing seal is visually recognized by a change in the aggregation form of the magnetic fluid can be used.
Furthermore, various magnetic sensors such as a magnetoresistive sensor that detects a change in magnetic field intensity as a change in magnetic resistance can be used instead of the magnetic impedance sensor.
The measurement result detected by the magnetic sensor can be displayed on a recorder or a cathode ray tube. MaTheIt can also be visually recognized as a form (aggregation) of magnetic fluids.
[0021]
[Example 1]
On the surface of the seal substrate made of cast-coated paper, urethane resin as a binder and hard magnetic Sm₂Fe₁₇N_ThreeThe magnetic magnet powder is mixed so that the mixing amount of the system magnet powder is 50% by mass, and the material is applied to form a magnetic layer. Furthermore, an acrylic pressure-sensitive adhesive is applied to the back surface of the seal substrate. The thickness of the sensing seal is 0.1 mm, the width is 5 mm, and the length is 15 mm. After application, it was magnetized with a magnetizer in the vertical direction of the seal.
Furthermore, in order to prevent oxidation, it is covered with a resin sheet (polyvinylidene chloride) that constitutes a protective layer that is difficult to pass oxygen, and when the fish is put in the case, the freshness sensing seal is peeled off and the resin sheet is peeled off. Affixed inside.
The relationship between the retention time in the atmosphere of the freshness sensing seal and the amount of decrease in magnetic field strength is measured in advance. The relationship between the holding time in the atmosphere (hours) and the amount of decrease in magnetic field strength (%) in the case of the freshness sensing seal used in the present example is shown by a straight line 1 in FIG.
After a certain period of time, a magnetic impedance sensor (Aichi Steel MI chip) detector 32 was adhered to the seal surface, and the magnetic field strength was measured.
The result was a decrease of 7.4% compared to the initial value. This amount of decrease indicates that the elapsed time is 80 hours from the straight line 1 in FIG. 2, while the elapsed time was measured with a clock, which almost coincided with the result. In Example 1, the magnetic layer is formed on the surface of the seal substrate, but may be formed on the back surface of the seal substrate, for example, between the seal substrate and the pressure-sensitive adhesive layer.
[0022]
FIG. 4 is a sectional view showing another example of the freshness sensing seal according to the present invention.
Compared to the freshness sensing seal 10 shown in FIG. 1, the freshness sensing seal 110 shown in FIG. 4 has magnetic material powder on the seal base material 112 instead of the magnetic base material layer 14 being formed on the surface of the seal base material 112. It is mixed.
Examples of the magnetic powder include hard magnetic Sm.₂Fe₁₇N_ThreeRare earth magnet powder and Nd₂Fe₁₄B-based rare earth magnet powder is used. When this magnetic powder comes into contact with oxygen, oxidation begins, and the oxidized portion is non-magnetic Sm.₂O_ThreeOr Nd₂O_ThreeAnd soft magnetic αFe, which degrades the hard magnetic properties.
In this case, hard magnetic Sm is added to the polyethylene resin as the material of the seal substrate 112.₂Fe₁₇N_ThreeThe rare earth magnet powder is mixed and kneaded, and is formed into a sheet by a known sheet forming apparatus, whereby the seal substrate 12 is formed.
The seal substrate 112 is formed to have a thickness of 0.5 mm, a width of 5 mm, and a length of 15 mm.
[0023]
A protective sheet 116 that is difficult to pass oxygen as a protective layer is temporarily attached to the surface of the seal substrate 112. As the protective sheet 116, aluminum foil, PVDC (polyvinylidene chloride), MXD-6 (metaxylylene diamine / azibic acid), PVA coated with vinylidene chloride, OPP, PET, ONY, aluminum-deposited CPP, A resin sheet such as PET on which PET, ONY, or silica is deposited is used. The protective sheet 116 is peeled off from the surface of the seal substrate 112 and temporarily attached to the surface of the peeled seal substrate 112 with a re-peelable adhesive.
The protective sheet 116 is for preventing the magnetic powder in the magnetic layer 14 from being oxidized by oxygen in the atmosphere.
[0024]
An adhesive layer 118 is formed on the back surface of the seal substrate 112. The pressure-sensitive adhesive layer 118 is for bonding the freshness sensing seal 110 to a packaging material or the like for a fresh food product whose freshness is to be detected. A known release mount 120 for temporarily protecting the surface of the pressure-sensitive adhesive layer 118 is temporarily attached.
[0025]
When the freshness sensing seal 110 shown in FIG. 4 is placed in the atmosphere with the protective sheet 116 peeled off, the magnetic powder in the seal substrate 112 is gradually oxidized. Therefore, the freshness sensing seal 110 shown in FIG. 4 shows the relationship between the time (time) placed in the atmosphere and the amount of decrease in magnetic field strength (%) when the protective sheet 116 is peeled off, as shown by the straight line 2 in FIG. In addition, the magnetic field strength decreases with time.
[0026]
Therefore, the freshness sensing seal 110 can monitor the time spent in the environment by detecting the change in the magnetic properties of the magnetic material due to the environment.
Therefore, the freshness sensing seal 110 can detect the freshness of, for example, fresh food items placed in the environment.
[0027]
Even when the freshness sensing seal 10 shown in FIG. 4 is used, the freshness of food, for example, can be detected or measured as in the case of using the freshness sensing seal 10 shown in FIG.
Next, an example in which the freshness of fish is detected or measured by the freshness sensing system 100 using the freshness sensing seal 110 and the magnetic impedance sensor (Aichi Steel MI chip) 30 will be described with reference to FIG.
[0028]
First, the freshness sensing seal 110 is attached to the inside of the case C containing fresh food, for example, fish, so that the same environmental change as the fish is peeled off from the peeling mount. In this freshness sensing seal 110, magnetic powder is mixed in the seal substrate 112, and the magnetic powder is pasted with the freshness sensing seal 110, and at the same time as the protective sheet 116 is peeled off, it starts to contact air. The magnetic powder gradually begins to oxidize.
The magnetic powder is wrapped in the base material of the seal, but oxygen gradually permeates the material of the seal base, so that the oxygen that reaches the magnetic powder contacts the magnetic powder and starts to oxidize.
Hard magnetic Sm as magnetic powder₂Fe₁₇N_ThreeRare earth magnet powder and Nd₂Fe₁₄B-based rare earth magnet powder is oxidized from the surface portion of the powder, but the oxidized portion is non-magnetic Sm.₂O_ThreeOr Nd₂O_ThreeAnd the hard magnetic properties are degraded.
[0029]
In detecting or measuring the freshness, the strength of the magnetic field appearing on the surface of the freshness sensing seal 110 is measured before applying the freshness sensing seal 110. That is, the detector 32 of the freshness sensing system 100 is put on the surface of the freshness sensing seal 110 and measured by the magnetic impedance sensor 30 to be an initial value.
Thereafter, the freshness sensing seal 110 is affixed, and the magnetic powder is oxidized. However, when it is necessary to know the freshness at a certain time, the magnetic field strength of the surface of the freshness sensing seal 110 is measured by the magnetic impedance sensor 30. Thus, the amount of change from the initial value is known. Since the amount of change is proportional to the logarithm of the elapsed time, the elapsed time can be known from the data obtained in advance.
If the magnetic powder of the freshness sensing seal 10 is previously magnetized or magnetized before being measured by the magnetic impedance sensor 30, for example, hard magnetic Sm₂Fe₁₇N_ThreeSince the magnetic field is generated from the powder, the magnetic field intensity can be measured by the magnetic impedance sensor 30.
The magnetic impedance sensor 30 has a detection sensitivity that is 1/1000 of the magnetic field strength (several gauss) equivalent to geomagnetism, and can measure even a weak magnetic field strength. It is a magnetic sensor that can be measured with sensitivity.
[0030]
As described above, the magnetic powder strength of the freshness sensing seal 110 gradually changes (decreases) due to oxidation starting from the application of the freshness sensing seal 110. By measuring this minute change in magnetic field intensity with a highly sensitive magnetic impedance sensor, the length of time in the atmosphere can be known. That elapsed time directly represents freshness.
[0031]
[Example 2]
Hard magnetic Sm on polyethylene resin as sealing material₂Fe₁₇N_ThreeThe mixture is mixed and kneaded so that the content of the rare earth magnet powder is 20% by mass, and is formed into a sheet with a known melt extrusion molding machine (manufactured by SHI Modern Machinery) to form a sheet substrate.
Next, an acrylic pressure-sensitive adhesive is applied to the back surface of the sheet base material.
The thickness of the sealing substrate is 0.5 mm, the width is 5 mm, and the length is 15 mm.
Furthermore, in order to prevent oxidation, it is covered with a resin sheet (aluminum foil), which is a protective layer that is difficult to pass oxygen, and when the fish is put in the case, this freshness sensing seal is peeled off and attached to the inside of the case. It was.
The relationship between the retention time in the atmosphere of the freshness sensing seal and the amount of decrease in magnetic field strength is measured in advance. The relationship between the retention time in the atmosphere (hours) and the amount of decrease in magnetic field strength (%) in the case of the freshness sensing seal used in this example is shown by line 2 in FIG.
After a certain period of time, a magnetic impedance sensor (Aichi Steel MI chip) detector 32 was adhered to the seal surface, and the magnetic field strength was measured.
The result was a 6.1% decrease compared to the initial value. This amount of decrease shows that the elapsed time is 90 hours from the straight line 2 in FIG. 2, while the elapsed time was measured with a clock, which almost coincided with the result.
[0032]
  Next, deformation of the freshness sensing seal shown in FIG.referenceAn example will be described mainly with reference to FIG.
  In this freshness sensing seal 210, as a magnetic powder, a ferrite oxide magnetic material Co that is a soft magnetic material is used._1-XZn_XFe₂O₄The magnetic layer 214 was formed on the surface of the sealing base material 212 using the above powder. This ferrite oxide has a magnetic disappearance temperature (Curie point) near room temperature. The Curie point can be changed by changing the Zn amount (X).
  The temperature that is important for freshness depends on the nature of the subject. In this embodiment, in the case of meat that is almost refrigerated and transported, the freshness sensing sticker that is pasted to know the maximum temperature at which the meat itself has been heated is moved from one refrigerator to the next. Formed.
  An adhesive layer 218 is formed on the back surface of the magnetic layer 214, and a release mount 220 is temporarily attached to the surface of the adhesive layer 218.
[0033]
[Reference example]
  First, the above Co_1-XZn_XFe₂O₄Four types of magnetism in which the composition X is changed to 0.700, 0.693, 0.686, and 0.679, and the Curie point becomes 0 ° C, 5 ° C, 10 ° C, and 15 ° C with cobalt ferrite made of powder. A body paint was prepared, and a magnetic paint was prepared by mixing urethane resin so that the content of each cobalt ferrite powder was 50% by mass. As shown in FIG. 5, the magnetic coating material was applied to a cast-coated paper as a sealing substrate with a width of 5 mm to form a magnetic layer. The sheet is formed with a thickness of 0.1 mm, a width of 45 mm, and a length of 55 mm.
  In the fluid powder used here, there is almost no irreversible change due to oxidation or the like at a temperature around room temperature.
  Here, the belt-like magnetic layer having four types of Curie points is referred to as a temperature detection unit.
[0034]
Before sticking this freshness sensing sticker to the meat pack of the subject, the freshness sensing sticker is magnetized in a vertical direction with a magnetizer, and then the atomized freshness sensing sticker is sprinkled with iron atomized powder in four types. Adsorbed to the temperature detector. Since the magnetic field is weak except for the temperature detector, the iron atomized powder is shaken off by shaking the freshness sensing seal. At this time, it is necessary to cool the freshness sensing sticker to below zero degree and finish the above-mentioned operation before raising the temperature to 0 ° C. After that, it is confirmed that the iron atomized powder is adsorbed on the four types of temperature detectors, and is affixed to the surface of the meat pack of the subject.
After this, the meat containing the sample pack was delivered in a refrigerated state, but when it arrived at the final meat store, the freshness sensing seal was checked. At this point in time, the iron atomized powder remained adsorbed on the four temperature detectors, and it was found that the temperature was kept below zero during delivery. Then, when the pack with the freshness sensing seal was taken out and left as it was at room temperature, the iron atomized powder at the 0 ° C and 5 ° C temperature detection portions of the freshness sensing seal had dropped. From this, it was found that the temperature rose to 5 ° C. or more and less than 10 ° C.
[0035]
The principle of the operation of this freshness sensing seal is that the cobalt ferrite of the temperature detection part is ferromagnetic when the temperature is below the Curie point, and the magnetic field emitted from the cobalt ferrite adsorbs the iron atomized powder. When the temperature rises and the cobalt ferrite in the temperature detector becomes above the Curie point, the magnetic field from the ferromagnetic ferrite is changed from ferromagnetism to paramagnetism, so there is no magnetic field on the surface of this temperature detector and the iron atomized powder is adsorbed. It cannot be kept and falls.
Even if the temperature drops again and this part becomes ferromagnetic again, the magnetization direction of each cobalt ferrite powder is different, so the magnetic field appearing on the surface is substantially 0, and the iron atomized powder that has fallen off and separated Is not adsorbed. In this case, the temperature detection unit not only detects the temperature but also has a display function.
This will memorize the highest temperature.
[0036]
In the freshness sensing seal 10 shown in FIG. 1, the magnetic layer 14 is formed on the entire surface of the seal substrate 12, but the magnetic layer 14 may be partially formed on the surface of the seal substrate 12. Good. In addition, a plurality of magnetic layers having different magnetic characteristics may be separately formed in a plurality of regions on the surface of the seal substrate 12.
[0037]
Further, in the freshness sensing seal 110 shown in FIG. 4, the magnetic powder is mixed in the entire seal base material 112, but the magnetic powder may be partially mixed in the seal base material 112. In addition, a plurality of magnetic layers having different magnetic characteristics may be divided into a plurality of regions and mixed separately into the seal substrate 112.
[0038]
Furthermore, in the freshness sensing seal 10 shown in FIG. 1 and each freshness sensing seal 110 shown in FIG. 4, for example, hard magnetic Sm is used as the magnetic material.₂Fe₁₇N_ThreeRare earth magnets and Nd₂Fe₁₄In the present invention, ferrite such as cobalt ferrite, barium ferrite, or strontium ferrite may be used as the magnetic material.
[0039]
Further, in the freshness sensing seal 10 shown in FIG. 1 and each freshness sensing seal 110 shown in FIG. 4, magnetic powder is used as the magnetic material, but in the present invention, the magnetic material is linear, foil-shaped or block-shaped. The magnetic material may be used.
[0040]
【The invention's effect】
  As described above, the sensing seal is attached to the subject according to the present invention.Food that isApply directly to the container or place it in its container.Food that isWhen you want to know the time that has been in the atmosphere, you can immediately measure, you can know immediately. This allows the subjectFood that isYou can know the freshness of the foodofTime management is easy.
  Since the sensing seal contains only a small amount of magnetic powder, the sealing price is low, and a magnetic sensing device using a magnetic impedance sensor includes, for example, a minute sensor head, a display panel, and a power supply of about several volts. Since it is a simple meter constructed from the above, it is an inexpensive, compact and portable device. As a result, the conventional problems of high cost and complexity can be solved.
[Brief description of the drawings]
FIG. 1 is an illustrative sectional view showing an example of a freshness sensing seal according to the present invention.
FIG. 2 is a graph showing the relationship between the time (time) placed in the atmosphere and the amount of decrease in magnetic field strength (%) in the freshness sensing seal shown in FIGS. 1 and 4;
FIG. 3 is an illustrative view showing a freshness sensing system using the freshness sensing seal and the magnetic impedance sensor shown in FIG. 1;
FIG. 4 is a cross-sectional view showing another example of a freshness sensing seal according to the present invention.
FIG. 5 shows a modification of the freshness sensing seal shown in FIG.referenceIt is a perspective view solution figure of an example.

Claims (7)

A sealing substrate, a sensing seal having a magnetic body for generating a magnetic field around the magnetic body state, and are not field intensity decreases in the sealing surface by oxidation in place environment, wherein the surface of the sealing base material to protect the magnetic protective layer is peeled off during use Ru are temporarily stuck, sensing seals for detecting the oxidation of the food by a decrease in field strength due to the magnetic body.   The sensing seal according to claim 1, wherein the magnetic body is coated on a surface of the seal substrate.   The sensing seal according to claim 1, wherein the magnetic body is mixed in the seal base material. The sensing seal according to any one of claims 1 to 3, wherein an adhesive layer is formed on a back surface of the seal substrate. A sensing system, comprising: the sensing seal according to any one of claims 1 to 4; and sensing means for sensing a magnetic field intensity on a surface of the sensing seal. It said sensing means is a magnetic impedance sensor, sensing system of claim 5. Attaching a sensing seal according to any one of claims 1 to 4 in cases where the food is accommodated a food directly, or package, or subject food housed a subject a subject and step includes the steps of sensing a magnetic field strength of the surface of the sensing seal, Se Nshingu method.

Images