JP2012163433A - Magnetic field reflective sensor, inspection device of presence/absence of attached document in packing box, and conductive film thickness measuring instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact magnetic field reflective sensor, when measuring a distance, exerting a high precision in a long detection distance and, when measuring the thickness of a conductive film, having a high output voltage.SOLUTION: A magnetic filed reflective sensor 1 includes: an exciter 10 that emits a primary magnetic field, or an alternate magnetic field, and causes a conductive object to generate an eddy current; a receiver 20 that detects a secondary magnetic field generated by the eddy current and generates a receiving signal; and a case 40 made of a nonconductive material and retaining the exciter 10 and the receiver 20. The exciter 10 includes: a portal exciting core 11 comprising a first leg part 111, a second leg part 112, and a beam part 113 connecting the two leg parts; and an exciting coil 16 wound around the beam part 113; and is disposed with the end face sides of the two leg parts facing the detecting direction. The receiver 20 comprises; a rod-like receiving core 21; and a receiving coil 26 wound around the receiving core 21; and is disposed at such a position and an angle as being close to the first leg part 111 and scarcely detecting the primary magnetic field emitted by the exciter 10.

Description

  The present invention provides a magnetic field reflection comprising an exciter that generates an eddy current in a conductive object by transmitting an alternating magnetic field, and a receiver that generates a received signal by detecting a secondary magnetic field generated by the eddy current. The present invention relates to a mold sensor, and further relates to an attached document presence / absence inspection device in a packaging box using the sensor and a conductive film thickness measuring device.

  Conventionally, in the pharmaceutical industry, aluminum blister sheets (also called PTP packaging) are widely used for packaging tablets and capsules. An aluminum blister sheet is obtained by placing tablets or capsules in a hard plastic that is dented into a tablet or capsule form and sealing with an aluminum film. And in the marketed medicine, it is common to be packaged and sold with an attached document in which precautions are described. By the way, pharmaceuticals are strictly required to be taken on the basis of precautions for use, and there has been a strong demand for a method for inspecting the presence of an attached document describing precautions for use after sealing a packaging box.

  For this reason, in some pharmaceutical manufacturing factories, in the final process before shipment, a method for inspecting the presence or absence of an attached document by measuring the mass of the sealed packaging box is performed. However, since the mass of the packaging box and the attached document changes due to moisture absorption, it is not easy to accurately check the presence of the attached document by measuring the mass.

  Therefore, the present inventor pays attention to the fact that the attached document in the packaging box is arranged so as to sandwich the aluminum blister sheet as shown in FIG. 10, and accurately determines the distance from the bottom of the packaging box to the aluminum blister sheet. If we could measure it, we thought that we could inspect the attached document.

  In order to measure this distance, an exciter that generates an alternating magnetic field toward the aluminum blister sheet to generate an eddy current in the aluminum blister sheet, and a received signal by detecting a secondary magnetic field generated by the eddy current. We thought that it would be sufficient to use a magnetic field reflection type sensor equipped with a receiver that generates According to this method, it is not necessary to consider moisture absorption of the packaging box and the attached document.

  However, since this sensor is attached to an existing production line, it must be small. In addition, the distance from the sensor to the aluminum blister sheet in the packaging box is about 20 mm at the maximum as shown in FIG. 10. For example, the conventional small magnetic field reflection type sensor as described in Patent Document 1 has such a long distance. The distance could not be measured with high accuracy.

  Moreover, although the object is different, various apparatuses for measuring the thickness of the conductive film have been proposed as those using a magnetic field reflection type sensor (for example, Patent Document 2). However, the technique described in Patent Document 2 does not calculate the thickness of the conductive film from the output voltage of the receiver, but also calculates the thickness of the conductive film from the phase angle of the output voltage. As described above, in the conventional magnetic field reflection type sensor, the output voltage of the receiver is not sufficient for the conductive film, and it is difficult to accurately measure the thickness of the conductive film.

JP 2002-90105 A JP 2001-209930 A

  The present invention has been made in view of such circumstances, and is a small magnetic field reflection device that is highly accurate at a long detection distance when measuring a distance and has a high output voltage when measuring the thickness of a conductive film. It is to provide a type sensor. Still another object of the present invention is to provide an attached document presence / absence inspection apparatus in a packaging box and a conductive film thickness measurement apparatus using the magnetic field reflection type sensor.

  In order to solve the above-mentioned problem, in the invention according to claim 1, an exciter that transmits a primary magnetic field that is an alternating magnetic field to generate an eddy current in a conductive object, and a secondary magnetic field generated by the eddy current A magnetic field reflection type sensor including a receiver that detects a signal and generates a reception signal, and a case made of a non-conductive material that holds the exciter and the receiver. The exciter includes: a first leg portion; It consists of a gate-shaped excitation core composed of a second leg and a beam connecting the two legs, and an excitation coil wound around the beam, and the end faces of the two legs are detected in the direction of detection. The receiver is composed of a rod-shaped receiving core and a receiving coil wound around the receiving core, and a primary magnetic field transmitted from the exciter in the vicinity of the first leg of the exciter. It is characterized by being arranged at a position and angle that are hardly detected.

  According to a second aspect of the present invention, in the magnetic field reflection type sensor according to the first aspect, the excitation core has a width of the second leg portion that is less than or equal to one half of the width of the first leg portion. . Note that the width of the leg here refers to the distance from the left end to the right end of each leg when the portal core is viewed from the front.

  The invention according to claim 3 generates a reception signal by transmitting a primary magnetic field that is an alternating magnetic field, generating an eddy current in a conductive object, and detecting a secondary magnetic field generated by the eddy current. The magnetic field reflection type sensor includes a receiver and a case made of a non-conductive material that holds the exciter and the receiver. The exciter is connected to the first leg and the upper part of the leg. An L-shaped excitation core composed of a beam part and an excitation coil wound around the beam part, arranged so that the end surface side of the first leg part faces the detection direction, It is composed of a rod-shaped receiving core and a receiving coil wound around the receiving core, and is arranged at a position and an angle where the primary magnetic field transmitted from the exciter is hardly detected in the vicinity of the first leg of the exciter. It is characterized by that.

  According to a fourth aspect of the present invention, in the magnetic field reflection type sensor according to any one of the first to third aspects, the receiving core has a circular or rounded rectangular cross-sectional shape. In the case of a rectangle, the length in the short direction is less than half of the length in the axial direction, and the receiving coil has a length in the axial direction that is less than half of the length in the axial direction of the receiving core. Is also wound around the detection direction side.

  The invention according to claim 5 is characterized in that, in the magnetic field reflection type sensor according to claim 4, the receiving coil is wound as close as possible to the end of the receiving core on the detection direction side.

  According to a sixth aspect of the present invention, in the magnetic field reflection type sensor according to any one of the first to fifth aspects, the end of the receiving core in the axial direction extends from the end of the exciting core toward the target. It is characterized in that the line to the end on the opposite side to the object side is within the range translated in the same direction as the longitudinal direction of the beam portion.

  The invention according to claim 7 is the magnetic field reflection type sensor according to any one of claims 1 to 6, further comprising a wedge-shaped receiver back plate made of a ceramic material having a thermal expansion coefficient equivalent to that of the excitation core. The receiver and the back plate of the receiver, the receiver back plate and the excitation core are fixed, and the position and inclination angle of the receiver with respect to the exciter are maintained.

  In the invention according to claim 8, in the magnetic field reflection type sensor according to claim 7, after the receiver and the exciter are fixed via the receiver back plate, the inclination angle of the excitation coil with respect to the beam portion of the excitation core And the receiver is in a state of hardly detecting the primary magnetic field transmitted from the exciter.

  In the invention according to claim 9, in the magnetic field reflection type sensor according to claim 8, after adjusting and fixing the inclination angle of the excitation coil with respect to the beam portion of the excitation core, the excitation core is made of the same material as the excitation core. A small piece is attached so that the receiver hardly detects the primary magnetic field transmitted from the exciter.

  According to a tenth aspect of the present invention, in the magnetic field reflection type sensor according to any one of the seventh to ninth aspects, a dent is provided on the receiver side surface of the case. A small piece of the same material is attached so that the receiver hardly detects the primary magnetic field transmitted from the exciter.

  In the attached document presence / absence inspection device in the packaging box of the invention according to claim 11, when the aluminum blister sheet and the attached document are transported by the transport device in a state packed in the packaging box, the presence or absence of the attached document in the packaging box And determining whether or not there is an attached document in the packaging box on the basis of a change in the reception signal generated by the magnetic field reflection sensor according to claim 1 and the receiver. The magnetic field reflection type sensor is arranged below the packaging box with the detection direction facing upward. In addition, the aluminum blister sheet referred to here is not only a tablet or capsule encased in a hard plastic dented into a tablet or capsule form, which is sealed with an aluminum film, but the entire surface of the powder or the like is also an aluminum film. The one covered with is also included.

  The invention according to claim 12 is an apparatus for measuring a thickness of a conductive film, wherein the magnetic field reflection sensor according to any one of claims 1 to 10 and a change in a reception signal generated by a receiver, And a calculation means for calculating the thickness of the conductive film, wherein the distance between the magnetic field reflection type sensor and the conductive film is made constant.

  The magnetic field reflection type sensor of the invention according to claim 1 has the following characteristics. First, the direction of the exciting coil is arranged substantially perpendicular to the detection direction. In general, in the magnetic field reflection type sensor, there are a method in which the direction of the exciting coil is arranged in parallel to the detection direction, and a method in which the direction is perpendicular to the detection direction. However, as shown in FIG. It is a method to do. In the present invention, the direction of the exciting coil is arranged substantially perpendicular to the detection direction, so that the primary magnetic field can be further extended as compared with the case where the exciting coil is arranged in parallel.

  Secondly, the exciter has a portal-type excitation core composed of a first leg part, a second leg part, and a beam part connecting the two leg parts. By winding the exciting coil around the beam portion, the primary magnetic field can be generated more strongly. Further, since the core shape is a gate shape, as shown in FIG. 3A, the magnetic flux density of the primary magnetic field in the detection direction is increased, and the magnetic field can be exerted farther. In general, the sensor is attached to the surrounding metal. However, the second leg portion can reduce the influence of the secondary magnetic field generated from the surrounding metal behind the sensor. The effect of the first leg will be described later.

  Third, the receiver is placed at a position and angle that hardly detects the primary magnetic field. That the receiver does not detect the primary magnetic field is a state in which the magnetic flux of the primary magnetic field is not linked to the receiving coil wound around the receiving core. In the magnetic field reflection type sensor, it is difficult to detect a slight change in the secondary magnetic field in a state where a large amount of the magnetic flux of the primary magnetic field is linked to the receiving coil. Due to the superposition of the waves, a slight change in the secondary magnetic field having a different phase is replaced by the phase difference of the strong primary magnetic field. In such a state, no matter how strong the primary magnetic field is, the interlinkage component of the primary magnetic field increases beyond the secondary magnetic field, and the sensitivity of the receiver does not increase. Further, in such a state, even if the reception gain is increased by the amplifier, the sensitivity to the strong primary magnetic field increases, and the sensitivity to the weak secondary magnetic field cannot be increased greatly. In the present invention, since the receiver is arranged at a position and an angle at which the magnetic flux of the primary magnetic field hardly interlinks, it can receive only the secondary magnetic field while being in the primary magnetic field. Changes can be detected.

  Fourth, the core of the exciter has a first leg. In order to reduce the size of the sensor, the receiver must be placed close to the excitation coil. However, if the receiver is arranged near the exciting coil in the absence of the first leg, in order to prevent the receiving coil wound around the receiving core from interlinking with the primary magnetic field, The inclination angle of the receiver is increased. And that is probably the cause, but the following inconvenience occurs. First, as shown in FIG. 4, the detection center is located at a position protruding from the sensor on the side opposite to the receiver. This is uncomfortable in use. Also, as shown in FIG. 6, the output voltage is low when the aluminum plate is brought closer from a distance along the detection center. Further, the output voltage when the aluminum plate is moved from the receiver side to the exciter side at a certain distance is not desirable as a sensor because three peaks are generated as shown in FIG.

  However, having the first leg solves these problems. The detection center is located in the vicinity of the receiver in the sensor as shown in FIG. Further, as shown in FIG. 6, the output voltage is high when the aluminum plate is brought closer from a distance along the detection center. In addition, the output voltage when the aluminum plate is moved from the receiver side to the exciter side at a certain distance is one peak as shown in FIG. Become. Along with the beam part, the first leg part has a function of weakening the primary magnetic field strength of the lateral outer space of the first leg part and changing the vector direction of the primary magnetic field leaking from the first leg part. This reduces the tilt angle of the receiver with respect to the detection direction.

  Fifth, the receiver has a rod-shaped receiving core. By having the rod-shaped receiving core, the secondary magnetic flux can be collected and the flux linkage density can be increased.

  Thus, according to the magnetic field reflection type sensor of the first aspect of the present invention, it is possible to increase the accuracy with a long detection distance when measuring the distance. Further, the output voltage can be increased when measuring the thickness of the conductive film. Further, the sensor itself can be reduced in size.

  According to the magnetic field reflection type sensor of the second aspect of the present invention, the excitation core has a width of the second leg portion equal to or less than half of the width of the first leg portion. In order for the first leg to exhibit the effect of blocking the primary magnetic field, a certain amount of width is required. However, the role of the second leg is to reduce the influence from the surrounding metal behind the sensor and to increase the magnetic flux density of the primary magnetic field in the detection direction, and does not require as much width as the first leg. . Therefore, there is no problem even if the width of the second leg portion is set to half or less of the width of the first leg portion. Thereby, a sensor can be reduced in size.

  The magnetic field reflection type sensor of the invention according to claim 3 is substantially the same as the structure of claim 1, but the excitation core is not a gate type but an L shape. As a result, although slightly susceptible to the influence of surrounding metal, as shown in FIG. 3 (b), the magnetic field can be expanded further as compared with the magnetic field reflection type sensor of claim 1. Other effects are the same as those of the first aspect.

  The magnetic field reflection type sensor of the invention according to claim 4 has the following characteristics. First, the receiving core has a circular or rounded rectangular cross-sectional shape. If the cross-sectional shape is circular, the diameter is round, and in the case of a rounded rectangular shape, the short-side length is less than half the axial length. It is a stick. Since the demagnetizing factor can be reduced by elongating the core shape, the sensitivity of receiving the secondary magnetic field can be increased.

  Second, the receiving coil wound around the receiving core has an axial length that is less than half of the axial length of the receiving core and is wound closer to the detection direction than the center of the receiving core. It is. The higher the frequency of the primary magnetic field generated from the exciting coil, the higher the electromotive force applied to the object. If the electromotive force is high, the eddy current density flowing through the object is high. If the eddy current density is high, the secondary magnetic field strength is strong. In order to measure the distance to a far object with high accuracy, a high operating frequency at which the returned secondary magnetic field is strong is advantageous. Moreover, the higher the frequency, the shallower the primary magnetic field that penetrates into the object due to the skin effect. A high operating frequency is also advantageous for measuring the thickness of very thin conductive films. On the other hand, when the frequency of the coil increases, the coil changes from inductive to capacitive and the impedance also increases. In the present invention, the number of turns is reduced by shortening the axial length of the receiving coil, the line capacitance is reduced, and the parallel resonant frequency is increased. Thereby, the inductivity can be maintained up to a high operating frequency and the impedance can be kept low.

  Thirdly, the receiving coil is wound closer to the end side than the center of the receiving core. This has the effect of reducing the inductance, and the impedance can be further reduced. Also, the receiving coil causes self-oscillation due to self-inductivity and stray capacitance, which appears as self-generated noise. The self-generated noise that adversely affects the measurement is preferably as small as possible. In the present invention, since the receiving coil is wound closer to the end side than the center of the receiving core, self-generated noise can be reduced as compared with the case where the receiving coil is wound at the center. This is presumed to be due to the fact that the equilibrium state, which is a necessary condition for oscillation, collapses when the center is shifted and wound, and as a result, self-oscillation is suppressed. Thereby, stable measurement can be performed.

  Thus, according to the magnetic field reflection type sensor of the invention of claim 4, it is possible to increase the accuracy with a longer detection distance when measuring the distance. Further, the output voltage can be increased by measuring the thickness of the conductive film.

  According to the magnetic field inverted sensor of the fifth aspect of the invention, the receiving coil is wound as close as possible to the end of the receiving core on the detection direction side. The magnetic flux of the secondary magnetic field that reaches the sensor from the far side in the detection direction is collected in the receiving core, but the magnetic flux density is highest at the end in the detection direction and lowest at the opposite end. By winding the receiving coil around the end portion on the detection axis direction side where the magnetic flux density is highest, the received electromotive force can be increased with a small number of turns.

  According to the magnetic field reflection type sensor of the invention according to claim 6, the height of the receiving core is within the range of the height of the exciting core. If the height of the receiving core exceeds the height of the excitation core, the receiving core absorbs the primary magnetic field, which greatly changes the spatial distribution of the primary magnetic field. As a result, the receiver is greatly affected by the primary magnetic field. According to the present invention, the receiver is not greatly affected by the primary magnetic field.

  According to the magnetic field reflection type sensor of the invention of claim 7, the receiver back plate made of a ceramic material having a thermal expansion coefficient equivalent to that of the exciting core is further provided. In the configuration in which the excitation coil is wound around the collar portion of the portal-type excitation core, the primary magnetic field strength of the lateral outer space of the first leg where the receiver is disposed is weakened by the first leg. The setting of the tilt angle of the receiver that makes the interlinkage magnetic flux of the primary magnetic field almost zero becomes delicate. The inclination angle of the receiver with respect to the first leg of the exciting core causes a large output change with a slight angle variation. Therefore, in the manufacturing process, when the receiver and the exciter are bonded and fixed, it is necessary to prevent the position and angle between the receiver and the exciter from fluctuating due to curing shrinkage. Further, even after manufacture, the receiver must be completely fixed at a position and an angle at which the primary magnetic field transmitted by the exciter is hardly detected. In the present invention, this is realized by bonding the receiver and the exciter through a wedge-shaped receiver back plate. In addition, the material of the receiver back plate is made of ceramic having a thermal expansion coefficient equivalent to that of the excitation core, so that the inclination angle of the receiver with respect to the first leg portion of the excitation core is suppressed as much as possible.

  According to the magnetic field reflection type sensor of the invention according to claim 8, after the receiver and the exciter are fixed via the receiver back plate, the inclination angle of the exciting coil with respect to the beam portion of the exciting core is adjusted. . The receiver tilt results in large output variations with small angular variations. For this reason, in order to make the receiver hardly detect the primary magnetic field transmitted from the exciter, fine angle setting and fixing are required. However, it is practically not easy to achieve both setting and fixing in the manufacturing process. By the way, the inclination adjustment of the excitation coil has a narrower adjustment range than the inclination adjustment of the receiver, but the output fluctuation for each angle is small and suitable for fine adjustment. For this reason, in the manufacturing process, after fixing the receiver and exciter through the receiver back plate, the primary magnetic field transmitted from the exciter can be reduced by adjusting the tilt angle of the exciting coil. The state where it is not detected is realized.

  According to the magnetic field reflection type sensor of the invention of claim 9, after adjusting and fixing the inclination angle of the exciting coil with respect to the beam portion of the exciting core, a small piece of the same material as that of the exciting core is further attached around the exciter. . Even when the inclination angle of the exciting coil is adjusted and fixed as described above, the positional relationship between the receiver and the exciting coil may be slightly shifted due to curing shrinkage of the adhesive, and further fine adjustment may be necessary. is there. For this reason, a small piece of the same material as the exciting core is attached around the exciter, and the spatial distribution of the primary magnetic field is slightly changed by adjusting the size and mounting position of the small piece, and the receiver is transmitted from the exciter. A state in which the primary magnetic field is hardly detected is realized.

  According to the magnetic field reflection type sensor of the invention according to claim 10, the case is provided with a recess on the side surface on the receiver side, and after the case is completed, a small piece of the same material as the excitation core is attached in the recess. When resin-casing the receiver and the exciter, the positional relationship between the receiver and the exciting coil may be slightly shifted due to curing shrinkage of the casting resin or the filling resin, and further fine adjustment may be required. For this reason, a space distribution of the primary magnetic field is provided by providing a recess on the side of the receiver outside the case, mounting a small piece of the same material as the excitation core in the recess, and adjusting the size of the small piece and the mounting position inside the recess. Is slightly changed so that the receiver hardly detects the primary magnetic field transmitted from the exciter.

  According to the attached document presence / absence inspection apparatus in the packaging box of the invention according to claim 11, a highly sensitive magnetic field reflection type sensor is used, and the sensor is arranged below the packaging box with the detection direction facing upward. Thereby, the difference in the distance between the bottom surface of the packaging box and the lowermost aluminum blister sheet can be detected with high accuracy, and as a result, the presence or absence of the attached document in the packaging box can be accurately inspected.

  According to the conductive film thickness measuring apparatus of the invention of claim 12, a highly sensitive magnetic field reflection type sensor is used, and the distance between the sensor and the conductive film is made constant. Accordingly, the thickness of the conductive film can be accurately measured based on the change in the reception signal generated by the receiver.

It is the schematic which showed the magnetic field reflection type sensor (Example 1). It is the figure which showed the breadth of the magnetic field when arrange | positioning perpendicularly | vertically when the direction of an exciting coil is arrange | positioned in parallel with respect to a detection direction. It is the figure which showed the breadth of the primary magnetic field at the time of employ | adopting a portal core and an L-shaped core. It is the figure which showed the detection center when there is no 1st leg part. It is the figure which showed the detection center in case there exists a 1st leg part. It is the figure which showed the output voltage when an aluminum plate was brought close from a distance along a detection center. It is the figure which showed the output voltage when moving an aluminum plate from the receiver side to the exciter side at a fixed distance. It is the schematic which showed the receiver. It is the schematic which showed the magnetic field reflection type sensor (Example 2). It is the schematic which showed the attached document presence / absence inspection apparatus (Example 3) in a packaging box. It is the figure which showed the output characteristic of the receiver of the attached document presence / absence inspection apparatus in a packaging box. It is the schematic which showed the thickness measuring apparatus (Example 4) of the electroconductive film.

  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying a magnetic field reflection type sensor, an attached document presence / absence inspection device in a packaging box, and a conductive film thickness measuring device according to the present invention will be described below with reference to the drawings.

(Magnetic reflection sensor 1)
First, the configuration of the magnetic field reflection sensor 1 according to the first embodiment will be described mainly with reference to FIG. The magnetic field reflection sensor 1 mainly includes an exciter 10, a receiver 20, a receiver back plate 30, and a case 40.

  The exciter 10 includes an excitation core 11 and an excitation coil 16. The excitation core 11 is configured by integrating a first leg 111, a second leg 112, and a beam 113 that connect the first leg 111 and the second leg 112, which face each other in parallel. A gate-type core. The width L2 of the second leg 112 is one third of the width L1 of the first leg 111. The material of the exciting core 11 preferably has an initial permeability of 1500 or more, and more preferably about 2300. Moreover, what has a high frequency characteristic with which initial permeability maintains the same numerical value to 150 kHz or more is preferable. Furthermore, the resistivity of the exciting core 11 is preferably 6.0 Ω · m or more, and more preferably about 13 Ω · m. In this embodiment, the material of the exciting core 11 is soft magnetic ferrite that satisfies the above conditions.

  The exciting coil 16 is wound around the flange 113 so that the inclination angle α can be adjusted in the manufacturing stage. That is, the exciting coil 16 is not directly wound around the flange portion 113 but is pre-molded and attached to the flange portion 113 from the second leg portion 112 side. The exciter 10 is disposed with the end surface of the first leg 111 and the second leg 112 opposite to the side where the flange 113 is connected facing the detection direction. The exciter 10 is connected to an external AC power source (not shown) via an excitation cable 17 and transmits an alternating magnetic field by an input signal from the external AC power source to generate an eddy current in a conductive object.

  The receiver 20 includes a reception core 21 and a reception coil 26. As shown in FIG. 8A, the receiving core 21 is a rod having a rounded rectangular cross section, and the length L3 in the short direction of the rounded rectangle is less than or equal to half of the axial length L4. In addition, the cross section of a core may be circular and two may be sufficient as shown in FIG.8 (b), for example. From the end of the receiving core 21 to the end in the axial direction, the line extending from the object-side end of the exciting core 11 to the end of the eaves 113 is within the range of E1 translated in the longitudinal direction of the eaves 113. It is in the range. The material of the receiving core 21 is soft magnetic ferrite similar to that of the exciting core 11.

  As shown in FIG. 8A, the receiving coil 26 is wound in a single layer in the vicinity of the end 21 a of the receiving core 21 on the detection direction side. The reason why the wire is wound around a single layer is to reduce the capacitance between the lines. The length L5 in the axial direction of the receiving coil 26 is not more than half of the length L4 in the axial direction of the receiving core 21.

  The receiver 20 is disposed in the vicinity of the first leg 111 of the excitation core 11 at a position and an angle at which the primary magnetic field transmitted from the exciter 10 is hardly detected. Specifically, the reception coil 26 side is directed in the detection direction, and the side opposite to the reception coil 26 is inclined in a direction away from the first leg portion 111 from a state in which the reception coil 26 side is substantially in close contact with the outside of the first leg portion 111. It is fixed to the excitation core 11 via the instrument back plate 30. The receiver 20 detects a secondary magnetic field generated by an eddy current generated in the object and generates a reception signal. The receiver 20 is connected to an arithmetic device or the like (not shown) via the reception cable 27.

  The receiver back plate 30 has a wedge shape at the tip in accordance with an angle at which the receiver 20 hardly detects the primary magnetic field transmitted from the exciter 10. The receiver back plate 30 is flat on the side of the exciter 10 and is joined to the outer surface of the first leg 111 of the excitation core 11. The receiver 20 and the receiver back plate 30, and the receiver back plate 30 and the excitation core 11 are fixed with an adhesive having low viscosity and high permeability. The receiver back plate 30 has a length equivalent to or slightly exceeding the height of the excitation core 11. The junction between the reception cable 27 and the reception coil 26 and the junction between the excitation cable 17 and the excitation coil 16 are fixed at positions away from the receiver 20 and the exciter 10. This is to reduce the influence on detection even if a positional shift occurs in the loop formed by each joint due to deformation of the case 40 due to heat or stress. The reception cable 27 and the excitation cable 17 are twisted two-core shielded cables. The receiver back plate 30 is made of a ceramic material having a thermal expansion coefficient equivalent to that of the excitation core 11. The receiver back plate 30 reliably holds the position and inclination angle of the receiver 20 with respect to the excitation core 11.

  The exciter 10, the receiver 20, and the receiver back plate 30 are placed on the detection face plate 31 and fixed by bonding. All of these on the detection face plate 31 are covered with a non-conductive resin, and this resin forms the case 40. The case 40 has a substantially rectangular parallelepiped shape, and a pocket 41 (corresponding to a dent in claim 10) is provided on the side surface of the receiver 20 side.

  Next, a manufacturing process of the magnetic field reflection type sensor 1 will be described. Since the inclination of the receiver 20 causes a large output fluctuation with a slight angle fluctuation, fine angle setting and fixing are required. However, it is not easy to achieve both setting and fixing. Therefore, the receiver 20 is manufactured as follows in order to obtain a state in which the primary magnetic field transmitted from the exciter 10 is hardly detected (hereinafter referred to as a primary magnetic field insensitive state).

  First, the receiver 20 is fixed to the receiver back plate 30, and the receiver back plate 30 is fixed to the excitation core 11. The receiver back plate 30 tilts the receiver 20 by a wedge-shaped angle, but the angle cannot be finely adjusted.

  Therefore, the inclination angle α of the exciting coil 16 is adjusted next to make the receiver 20 insensitive to the primary magnetic field. The inclination adjustment of the exciting coil 16 is suitable for fine adjustment because the output fluctuation for each angle is small compared to the inclination adjustment of the receiver 20. After the excitation coil 16 is tilted, it is bonded and fixed with a ceramic adhesive or dental glass ionomer cement. These adhesives have thermal expansion coefficients close to those of ceramics and ferrite materials.

  Still, the primary magnetic field insensitive state may collapse due to curing shrinkage of the adhesive or the like. In that case, fine adjustment is performed by adhering a small ferrite piece 50 (corresponding to the small piece in claim 9) smaller than the exciting core 11 to the exciting core 11. Specifically, the primary magnetic field insensitive state is achieved by adjusting the size and mounting position of the ferrite piece 50.

  Thereafter, the case 40 is formed by molding by integral molding so as to cover all of the exciter 10, the receiver 20, and the receiver back plate 30 that are placed on and fixedly bonded to the detection face plate 31. The case 40 may be formed by placing all of the above in a resin outer frame and filling the inside with resin. The case 40 is formed in a substantially rectangular parallelepiped shape, and a pocket 41 (corresponding to a dent in claim 10) is formed on the side surface of the receiver 20 side.

  However, even if the receiver 20 is carefully adjusted so as to be insensitive to the primary magnetic field so far, the primary magnetic field insensitive state collapses due to shrinkage of the casting resin or the filling resin during the curing of the case 40. May end up. In this case, fine adjustment is performed by attaching a ferrite small piece 51 (corresponding to the small piece in claim 10) in the pocket 41. Specifically, the primary magnetic field insensitive state is obtained by adjusting the size of the ferrite piece 51 and the mounting position inside the pocket 41. After adjustment, the pocket 41 is closed with resin.

  In addition, the usage method etc. of the magnetic field reflection type sensor 1 are demonstrated concretely in Example 3. FIG.

(Magnetic reflection sensor 2)
The magnetic field reflection type sensor 2 according to the second embodiment has substantially the same configuration as the magnetic field reflection type sensor 1, and therefore only the differences will be described. In addition, about the same structure, the code | symbol same as the magnetic field reflection type sensor 1 is attached | subjected.

  As shown in FIG. 9, in the magnetic field reflection type sensor 2, the exciting core 12 is L-shaped. As a result, although slightly susceptible to the influence of the secondary magnetic field generated from the surrounding metal, as shown in FIG. The method of using the magnetic field reflection type sensor 2 is the same as that of the magnetic field reflection type sensor 1.

(Inspection device for attached documents in the packaging box)
Next, the configuration of the attached document presence / absence inspection device 3 (hereinafter referred to as the inspection device 3) in the packaging box of Example 3 will be described mainly with reference to FIG. The inspection device 3 is a device that inspects the presence or absence of the attached document 71 in the packaging box 70 when the packaging box 70 is conveyed on the belt 80 by a conveyance device (not shown).

  The attached document 71 is packed in the packaging box 70 so as to sandwich the aluminum blister sheet 72. Accordingly, the lowermost aluminum blister sheet 72 is at a high position when the attached document 71 is present, and is lowered to a low position by the gravity of the earth when the attached document 71 is absent. The inspection device 3 uses this, and inspects the presence or absence of the attached document 71 by the difference in the distance from the bottom surface of the packaging box 70 to the aluminum blister sheet 72.

  The metal used for the aluminum blister sheet 72 is usually aluminum, but the material is not particularly limited as long as it is a metal. The packaging box 70 is usually made of paper, but regardless of the material, the packaging box 70 may be further covered with a plastic film or the like.

  A conveyance device (not shown) moves the packaging box 70 in parallel to the short direction of the packaging box 70 (in FIG. 10, from the back to the front or from the front to the back). Moreover, the passing position of the packaging box 70 is constant at the position where the inspection device 3 is installed.

  The inspection apparatus 3 is mainly configured by the magnetic field reflection type sensor 1 of the first embodiment and a control unit 60 (corresponding to a determination unit in claim 11). The magnetic field reflection type sensor 1 is disposed below the packaging box 70 with the detection direction facing upward. More specifically, the magnetic field reflection type sensor 1 is not located directly under the center of the packaging box 70 but is shifted toward the side where there is an attached document. The magnetic reflection sensor 1 is oriented so that the longitudinal direction of the flange 113 of the exciting core 11 is the longitudinal direction of the packaging box so that the receiver 20 side is the center side of the packaging box 70 and the exciter 10 side is the attached document side. The direction is consistent with. The accurate attachment position of the magnetic field reflection type sensor 1 is such that the center in the short direction, which is the conveyance direction of the packaging box 70, coincides with the detection center of the magnetic field reflection type sensor 1. And the point where the output voltage generated by the receiver 20 is maximized. That is, the alternating magnetic field transmitted from the exciter 10 generates an eddy current in the lowermost aluminum blister sheet 72, and the received signal obtained by detecting the secondary magnetic field generated by the eddy current by the receiver 20 is obtained. It is arranged to be the maximum level.

  The control unit 60 is connected to the exciter 10 via the excitation cable 17. The control unit 60 includes an AC power supply unit, and applies an AC current to the exciter 10. The control unit 60 is connected to the receiver 20 via the reception cable 27. The control unit 60 inputs the signal generated by the receiver 20 and determines the presence or absence of the attached document 71.

  The distance between the magnetic field reflection type sensor 1 and the lowermost aluminum blister sheet 72 is not particularly limited as long as it is within the maximum detection distance, but the distance as close as possible depends on the distance between the magnetic field reflection type sensor 1 and the aluminum blister sheet 72. The difference in output voltage is increased, resulting in a more stable inspection result against vibration and positional deviation due to conveyance.

  The procedure for judging the shortage of attached documents is shown. First, the attached document 71 is removed from the packaging box 70, the packaging box 70 is placed at a position where the detection center of the magnetic field reflection type sensor 1 passes through the center of the packaging box 70 in the short direction, and the output voltage of the receiver 20 is the saturation voltage. The current applied to the exciter 10 is set to be slightly below 10V. The control unit 60 stores the output voltage at this time as an insufficient value. Next, insert the attached document and check the output voltage level. The output value at this time is stored in the control unit 60 as a normal value. Then, the control unit 60 sets the threshold value to a value approximately between the normal value and the deficient value. The above function of the control unit 60 uses a known technique.

  The output voltage of the receiver 20 is at the lowest voltage level when the packaging box 70 is not located above the magnetic field reflection type sensor 1, and the output voltage increases as the packaging box 70 passes. If there is no attached document, the output voltage is high and becomes insufficient. If an attached document is included, the output voltage is low and normal. In actual inspection, since the packaging box 70 is moved on the belt 80 by the conveying device, the output voltage of the receiver 20 changes as shown in FIG. Times t <b> 1 and t <b> 2 are times when the center of the packaging box 70 in the short direction passes through the detection center of the magnetic field reflection type sensor 1. At this time, the output voltage of the receiver 20 becomes the maximum value. Therefore, the control unit 60 determines the presence or absence of the attached document 71 in the packaging box 70 by measuring the maximum value of the output voltage and comparing it with a threshold value. Note that the presence or absence of the attached document can be similarly determined by using the output current instead of the output voltage.

  Specifically, the control unit 60 acquires the output voltage of the receiver 20 and measures the maximum value. Then, the control unit 60 compares the maximum value with the threshold value, and stores the maximum value and the number of times the maximum value appears if the threshold value is within the threshold range. Thereby, it can be grasped how many normal packaging boxes 70 containing the attached document 71 have passed. If the maximum value is outside the threshold range, the control unit 60 sends a signal to a discharge device (not shown) to discharge the abnormal packaging box 70 from the transport device, turns on a lamp (not shown), and sounds a buzzer. . Thereby, it can be confirmed that the packaging box 70 not including the attached document 71 has been removed. The above function of the control unit 60 uses a known technique.

  In the present embodiment, the fact that the distance from the bottom surface of the packaging box 70 to the lowermost aluminum blister sheet 72 changes depending on the presence or absence of the attached document 71 is used. In order to detect the difference in distance with high accuracy, the highly sensitive magnetic field reflection type sensor 1 is used. However, a sensor other than the magnetic field reflection type sensor 1 can be used as long as the sensor has equivalent or better performance.

(Conductive film thickness measuring device)
Next, the configuration of the conductive film thickness measuring device 4 (hereinafter referred to as the measuring device 4) of Example 4 will be described mainly with reference to FIG. The measuring device 4 is a device that measures the thickness of a conductive film formed on a non-conductive substrate.

  In this embodiment, for the sake of convenience, the object will be described as being a conductive ITO film 91 applied on a glass substrate 90. However, the object is an aluminum vapor deposition film other than the ITO film, and its metal vapor deposition. It may be a film, and the substrate may not be glass as long as it is a nonconductor.

  The measuring device 4 includes the magnetic field reflection type sensor 1 according to the first embodiment, a control unit 61 (corresponding to calculation means in claim 12), and a table 81. The magnetic field reflection type sensor 1 is disposed below the cradle 81 with the detection direction facing upward. That is, the alternating magnetic field transmitted from the exciter 10 generates an eddy current in the ITO film 91 on the glass substrate 90 placed on the table 81, and the receiver 20 generates a secondary magnetic field generated by this eddy current. It is configured to detect and generate a received signal.

  The control unit 61 is connected to the exciter 10 via the excitation cable 17. The control unit 61 includes an AC power supply unit capable of changing the frequency for applying an AC current to the exciter 10. The control unit 61 has a permeability, conductivity, and thickness of a conductive film that is an object to be measured. The optimum operating frequency can be selected according to the range. The control unit 61 is connected to the receiver 20 via the reception cable 27. The control unit 61 receives the signal generated by the receiver 20 and calculates the thickness of the ITO film 91.

  The distance between the magnetic field reflection type sensor 1 and the ITO film 91 is not particularly limited as long as it is within the maximum detection distance. However, when the distance is as close as possible, the difference in output voltage due to the thickness of the ITO film 91 increases and the distance is more stable. Bring measurement results.

  When placing the ITO film 91 on the glass substrate 90 on the table 81, the surface of the ITO film 91 may be up or the surface of the glass substrate 90 may be up. In order to keep the distance constant, the same surface must always be up. Further, as long as the distance from the ITO film 91 can be kept constant, the magnetic field reflection type sensor 1 may be disposed above the table 81 with the detection direction of the magnetic field reflection type sensor 1 facing downward.

  Next, a procedure for measuring the thickness of the ITO film 91 will be described. First, a thickness sample with a predetermined interval covering the range to be measured is prepared. Then, the sample with the thickest ITO film 91 is placed on the table 81, and the current applied to the exciting coil 10 is set so that the output voltage of the receiver 20 is slightly below the saturation voltage of 10V. The output voltage at this time is stored in the control unit 61 in association with the thickness. Next, the prepared samples are placed on the placing table 81 one by one, and each output voltage is stored in the control unit 61 in association with the thickness. Then, the control unit 61 calculates an approximate expression for the relationship between the thickness and the output voltage. The above function of the control unit 61 uses a known technique.

  At the time of measurement, the ITO film 91 on the glass substrate 90 is placed on the placing table 81, an alternating current is applied to the exciter 10, and the output voltage generated by the receiver 20 is sent to the control unit 61. The control unit 61 applies the output voltage to the approximate expression, calculates the thickness of the ITO film 91, and displays it on a display unit (not shown). The above function of the control unit 61 uses a known technique.

1: Magnetic reflection type sensor 2: Magnetic reflection type sensor 3: Inspection device for attached document in packaging box 4: Thickness measuring device for conductive film 10: Exciter 11: Excitation core 12: Excitation core 16: Excitation coil 17 : Excitation cable 20: Receiver 21: Reception core 26: Reception coil 27: Reception cable 30: Receiver back plate 31: Detection face plate 40: Case 41: Pocket (corresponding to a dent)
50: Ferrite small piece (corresponding to small piece) 51: Ferrite small piece (corresponding to small piece)
60: Control unit (corresponding to determination means) 61: Control unit (corresponding to calculation means)
70: Packaging box 71: Attached document 72: Aluminum blister sheet 80: Belt 81: Stand 90: Glass substrate 91: ITO film 111: First leg 112: Second leg 113: Ridge

Claims (12)

An exciter that generates an eddy current in a conductive object by transmitting a primary magnetic field that is an alternating magnetic field;
A receiver that generates a reception signal by detecting a secondary magnetic field generated by the eddy current;
A magnetic field reflection sensor comprising a case made of a non-conductive material that holds the exciter and the receiver,
The exciter includes a portal-type excitation core composed of a first leg, a second leg, and a beam connecting the two legs, and an excitation coil wound around the beam. , Arranged so that the end face side of the two legs is directed in the detection direction,
The receiver comprises a rod-shaped receiving core and a receiving coil wound around the receiving core,
A magnetic field reflection type sensor, wherein the magnetic field reflection type sensor is disposed in the vicinity of the first leg portion of the exciter at a position and an angle at which a primary magnetic field transmitted from the exciter is hardly detected.   2. The magnetic field reflection sensor according to claim 1, wherein the excitation core has a width of the second leg portion equal to or less than a half of a width of the first leg portion. An exciter that generates an eddy current in a conductive object by transmitting a primary magnetic field that is an alternating magnetic field;
A receiver that generates a reception signal by detecting a secondary magnetic field generated by the eddy current;
A magnetic field reflection sensor comprising a case made of a non-conductive material that holds the exciter and the receiver,
The exciter includes an L-shaped excitation core composed of a first leg and a beam connected to the upper part of the leg, and an excitation coil wound around the beam. It is arranged so that the end face side of one leg portion faces the detection direction,
The receiver includes a rod-shaped receiving core and a receiving coil wound around the receiving core, and a position where the primary magnetic field transmitted from the exciter is hardly detected in the vicinity of the first leg of the exciter. And a magnetic field reflection type sensor arranged at an angle. The receiving core has a circular or rounded rectangular cross section, a diameter when the cross sectional shape is circular, and a short round length when the rounded rectangular shape is less than half of the axial length,
2. The receiving coil has an axial length that is not more than half of an axial length of the receiving core, and is wound closer to a detection direction side than a center of the receiving core. The magnetic field reflection type sensor according to any one of?   The magnetic field reflection sensor according to claim 4, wherein the receiving coil is wound as close as possible to an end of the receiving core on the detection direction side.   From the end in the axial direction of the receiving core, the line from the end on the object side of the exciting core to the end on the opposite side to the object side is the same as the longitudinal direction of the beam section. The magnetic field reflection type sensor according to claim 1, wherein the magnetic field reflection type sensor is within a range translated in parallel.   It further comprises a wedge-shaped receiver back plate made of a ceramic material having a thermal expansion coefficient equivalent to that of the excitation core, and the receiver and the receiver back plate, and the receiver back plate and the excitation core are fixed with an adhesive. The magnetic field reflection type sensor according to claim 1, wherein a position and an inclination angle of the receiver with respect to the exciter are maintained.   After fixing the receiver and the exciter through the receiver back plate, the inclination angle of the excitation coil with respect to the beam portion of the excitation core is adjusted, and the receiver is transmitted from the exciter. 8. The magnetic field reflection type sensor according to claim 7, wherein a primary magnetic field is hardly detected.   After adjusting and fixing the inclination angle of the excitation coil with respect to the beam portion of the excitation core, a small piece of the same material as the excitation core is further attached around the exciter, and the receiver transmits a primary signal from the exciter The magnetic field reflection type sensor according to claim 8, wherein the magnetic field is hardly detected.   A recess is provided on the receiver side surface of the case, and after the case is completed, a small piece of the same material as the excitation core is further attached in the recess, and the receiver transmits a primary signal from the exciter. The magnetic field reflection type sensor according to claim 7, wherein a magnetic field is hardly detected. A device for inspecting the presence or absence of the attached document in the packaging box when the aluminum blister sheet and the attached document are conveyed by the conveying device in a state packed in the packaging box,
Magnetic field reflection type sensor according to any one of claims 1 to 10,
Determination means for determining the presence or absence of the attached document in the packaging box based on a change in a reception signal generated by the receiver;
The attached document presence / absence inspection apparatus in a packaging box, wherein the magnetic field reflection type sensor is arranged below the packaging box with a detection direction facing upward. An apparatus for measuring the thickness of a conductive film,
Magnetic field reflection type sensor according to any one of claims 1 to 10,
Calculating means for calculating the thickness of the conductive film based on a change in the received signal generated by the receiver;
An apparatus for measuring a thickness of a conductive film, wherein a distance between the magnetic field reflection type sensor and the conductive film is constant.

Images