JP2008039542A - Magnetic tape film thickness measuring device and film thickness measuring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a film thickness measuring device and a film thickness measuring method which accurately measures the film thickness of a magnetic film even when a magnetic tape running among rolls wobbles. <P>SOLUTION: Primary X-rays x<SB>1</SB>are irradiated with a predetermined incident angle from an X-ray tube 4 arranged on the surface side of the magnetic tape T, and the intensity of fluorescence X-rays f<SB>1</SB>generated from a target element in the magnetic film 3 is detected by a semiconductor detector 11 arranged in the reflection angle corresponding to the incident angle. Primary X-rays x<SB>2</SB>are irradiated with an X-ray tube 5 opposing the X-ray tube 4 on the surface side being arranged on the rear side of the magnetic tape T, and the intensity of fluorescence X-rays f<SB>2</SB>generated from the target element is detected by a semiconductor detector 12 arranged opposing the semiconductor detector 11 on the surface side. Even when the magnetic tape T wobbles, the total value of a count value of the intensity of the fluorescence X-ray f<SB>1</SB>detected by the semiconductor detector 11 and a count value of the intensity of the fluorescence X-ray f<SB>2</SB>detected by the semiconductor detector 12, provides the exact film thickness of the magnetic layer 3. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a film thickness measuring apparatus and a film thickness measuring method for a magnetic tape, and more specifically, a film thickness measurement for accurately measuring the film thickness of a coating film on a magnetic tape while the magnetic tape is running in the manufacturing process. The present invention relates to an apparatus and a film thickness measuring method.

  The magnetic layer in LTO (Linear Tape Open Standard) etc. for high-density information recording magnetic tape has a multilayer structure as shown in FIG. 6, for example, on the base film B of PET (polyethylene terephthalate). Two layers consisting of the lower nonmagnetic layer 2 and the upper magnetic layer 3 are formed, or more layers are formed. When a magnetic tape capable of high-density recording with the above two-layer structure is used, the thickness of the upper magnetic layer 3 tends to be a thin film on the order of several tens of nm. If the film thickness of the magnetic layer 3 is not uniform, the recording characteristics are greatly deteriorated, so it is important how to accurately measure the film thickness of the magnetic layer 3 and how to make the film thickness uniform. It has become.

  As a method for measuring the film thickness, there are a method for obtaining transmittance using a laser beam and the like, and an X-ray diffraction method. Besides these, as shown in FIG. 7, a target element is added to the magnetic layer 3 to be measured. The primary X-ray x is incident on the magnetic tape T from the X-ray tube 4, the intensity of the fluorescent X-ray f generated from the target element is detected by the semiconductor detector 11, and the thickness of the magnetic layer 3 There is a way to measure. This target element may be added to the nonmagnetic layer 2 to measure the film thickness of the nonmagnetic layer, or by adding different types of target elements to a plurality of arbitrary layers having a multilayer structure, It has the advantage that the film thickness of each of the multiple layers to which the element is added can be measured simultaneously (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 02-013803

  When measuring the film thickness of the magnetic layer in-line using the X-ray fluorescence analysis method, that is, while the magnetic tape is running in the manufacturing process, in addition to increasing the measurement accuracy, it is also important how to reduce the measurement time. is there. The fluorescent X-ray detectors used in the fluorescent X-ray analysis include a wavelength dispersion type and an energy dispersion type. Although the energy dispersive detector is inferior in wavelength resolution, it is preferable in that it can detect many kinds of elements simultaneously in a short time, and is widely used.

  The magnetic tape T has a coating film made of a magnetic material such as iron or cobalt on a base film B such as PET having a thickness of several meters, and a binding material mainly composed of a vinyl chloride copolymer resin for binding them. The magnetic layer 3 is formed extremely thin and dried. Therefore, as shown in FIG. 8, the primary X-ray x incident from the X-ray tube 4 passes through the magnetic tape T and penetrates to the back surface side. When present, in addition to the fluorescent X-rays f from the magnetic tape T, a large amount of fluorescent X-rays f ′ from the constituent elements of the guide roll 20 are generated. In order to avoid this, as shown in FIG. 9, the film thickness of the magnetic film 3 is measured in a state where nothing exists on the back side of the incident point of the primary X-ray x on the magnetic tape T.

  However, in the process of applying and drying the magnetic coating on the magnetic tape T, the base film B or the magnetic tape T travels while being guided by a plurality of traveling rolls 20, and the traveling base film B or the magnetic tape T has a traveling speed or A slight fluctuation in tension causes a flutter between the traveling rolls 20 and 20. This fluttering naturally occurs when measuring the film thickness of the magnetic layer 3 in the magnetic tape T shown in FIG. 9, and as shown in FIG. 10, the film comprising the X-ray tube 4 and the semiconductor detector 11 is used. The distance g between the thickness measuring unit 10 and the magnetic tape T is changed. FIG. 11 is a diagram showing the relationship between the distance g between the magnetic tape T and the film thickness measurement unit 10 obtained by experiment and the intensity of the detected fluorescent X-ray f, and when the distance g is 1 mm away, the fluorescent X-ray The intensity of f decreases from about 4450 cps to about 4100 cps in terms of count value. The decrease in the count value corresponds to a decrease of about 20% in the film thickness according to the calibration curve indicating the relationship with the film thickness of the magnetic layer 3. The fluttering of the magnetic tape T becomes more severe as the width of the base film B becomes larger, and there is a problem that it is difficult to measure the film thickness of the magnetic layer 3 with high accuracy.

  The present invention has been made in view of the above problems, and when measuring the film thickness of a magnetic film or nonmagnetic layer of a magnetic tape running between rolls, even if the magnetic tape flickers, the magnetic film or nonmagnetic layer It is an object of the present invention to provide a film thickness measuring apparatus and a film thickness measuring method capable of accurately measuring a film thickness.

  The above problem can be solved by the structure of the first or sixth aspect. The means for solving the problem will be described as follows.

The apparatus for measuring a thickness of a magnetic tape according to claim 1 applies the coating of the non-magnetic layer to the surface of the traveling plastic film, applies the coating of the magnetic layer thereon without drying, and then dries both. In a magnetic tape film thickness measuring apparatus that measures the film thickness of a magnetic layer or a nonmagnetic layer of a magnetic tape formed in-line immediately after drying, a predetermined incident angle toward the magnetic tape on the surface side of the magnetic tape a first 1X-ray tube which enters the primary X-ray x ₁ in, receives a primary X-ray x _1, to detect the fluorescent X-ray f ₁ generated from the target element that is previously added to the magnetic layer or nonmagnetic layer A second X-ray tube in which the first semiconductor detector is disposed in the direction of the reflection angle corresponding to the incident angle, and the primary X-ray x ₂ is incident on the back surface side of the magnetic tape at a predetermined incident angle toward the magnetic tape. Sphere and primary x-ray x ₂ The second semiconductor detector for detecting the fluorescent X-ray f ₂ generated from the get element is an apparatus arranged in the direction of the reflection angle corresponding to the incident angle.

Such a magnetic tape film thickness measuring device detects the intensity of the fluorescent X-ray f ₁ detected by the first semiconductor detector on the front side of the magnetic tape and the second semiconductor detector on the back side of the magnetic tape. By calculating the film thickness based on the intensity of the fluorescent X-ray f ₂ , the running magnetic tape flickers, for example, the magnetic tape approaches the first X-ray tube and the first semiconductor detector side, When the intensity of the fluorescent X-ray f ₁ detected by the first semiconductor detector increases, the magnetic tape moves away from the second X-ray tube and the second semiconductor detector, and the fluorescent X-ray detected by the second semiconductor detector. Since the intensity of f ₂ decreases, the sum of the intensity detected by the first semiconductor detector and the intensity detected by the second semiconductor detector is the same as the sum of the intensity when the magnetic tape is not fluttered. Is equivalent to

The apparatus for measuring a thickness of a magnetic tape according to claim 2 is such that the primary X-ray x ₁ incident from the first X-ray tube and the primary X-ray x ₂ incident from the second X-ray tube are coaxial. The first X-ray tube and the second X-ray tube are arranged to face each other via a magnetic tape. Similarly, the first semiconductor detector and the second semiconductor detector are arranged to face each other via a magnetic tape. It is a device.

Such an apparatus for measuring the thickness of a magnetic tape has a structure in which a magnetic tape of primary X-ray x ₁ from the first X-ray tube enters the second semiconductor detector, and from the second X-ray tube. Counting ability in the portion that counts the intensity of the fluorescent X-ray f ₁ detected by the first semiconductor detector is prevented from being transmitted through the magnetic tape of the primary X-ray x ₂ to the first semiconductor detector. Is not saturated, and the counting capability in the portion for counting the intensity of the fluorescent X-ray f ₂ detected by the second semiconductor detector is not saturated.

According to a third aspect of the present invention, there is provided the magnetic tape film thickness measuring apparatus according to the first semiconductor detector, which is detected by the first semiconductor detector according to the thickness of the magnetic layer or the nonmagnetic layer to which the target element is added. count value of the intensity of the fluorescent X-ray f ₁ counted by the counting circuit, and a fluorescent X-ray f ₂ counted by the second counting circuit connected to the detected second semiconductor detector by the second semiconductor detector A measuring device that calculates the total value of the intensity count value and compares the total value with a previously prepared calibration curve to measure the film thickness of the magnetic layer or the nonmagnetic layer is provided in the first counting circuit and the second counting circuit. It is a connected device.

In such a magnetic tape film thickness measuring device, the count value of the fluorescent X-ray f ₁ by the first counting circuit and the count value of the fluorescent X-ray f ₂ by the second counting circuit are summed in the measuring device, and the sum is obtained. Since the value is compared with the calibration curve and the film thickness of the magnetic layer or the non-magnetic layer of the magnetic tape is measured, a highly accurate film thickness is provided even if the magnetic tape flickers.

According to a fourth aspect of the present invention, there is provided a magnetic tape film thickness measuring apparatus in which the counting of the fluorescent X-ray f ₁ by the first counting circuit and the counting of the fluorescent X-ray f ₂ by the second counting circuit are synchronously counted.

In such a magnetic tape film thickness measuring apparatus, the counting of the fluorescent X-ray f ₁ by the first counting circuit and the counting of the fluorescent X-ray f ₂ by the second counting circuit are simultaneously performed on the front and back of the same part of the magnetic tape. .

  The apparatus for measuring a thickness of a magnetic tape according to claim 5 is such that the first X-ray tube and the first semiconductor detector, and the second X-ray tube and the second semiconductor detector are integrated with the traveling magnetic tape. Is a device installed so as to be able to reciprocate in the width direction of a perpendicular magnetic tape.

Such a magnetic tape film thickness measuring device, since the primary X-ray x ₁ and the primary X-ray x ₂ is incident in a spot shape, a line shape along the running direction of the magnetic tape in the case of not moving the measurement spot However, the film thickness over the entire surface of the magnetic tape can be measured by reciprocating the measurement spot in the width direction.

The method for measuring a film thickness of a magnetic tape according to claim 6, wherein the coating of the nonmagnetic layer is applied to the surface of the traveling plastic film, and the coating of the magnetic layer is applied on the surface without drying. In the magnetic tape film thickness measuring method for measuring the film thickness of the magnetic layer or nonmagnetic layer of the magnetic tape formed in-line immediately after drying, the magnetic tape from the first X-ray tube disposed on the surface side of the magnetic tape to toward by the incidence of the primary X-ray x ₁ at a predetermined incident angle, receives the primary X-ray x _1, magnetic tape fluorescent X-ray f ₁ generated from the pre-added target element in the magnetic layer or nonmagnetic layer Detected by a first semiconductor detector arranged in the direction of the reflection angle corresponding to the incident angle on the surface side of
At the same time, a primary X-ray x ₂ is incident at a predetermined incident angle from a second X-ray tube disposed on the back side of the magnetic tape toward the magnetic tape, and the primary X-ray x ₂ is received and generated from the target element. Fluorescent X-ray f ₂ is detected by a second semiconductor detector disposed in the direction of the reflection angle corresponding to the incident angle on the back side of the magnetic tape,
The film thickness of the magnetic layer or the nonmagnetic layer is measured based on the intensity of the fluorescent X-ray f ₁ detected by the first semiconductor detector and the intensity of the fluorescent X-ray f ₂ detected by the second semiconductor detector. Is the method.

Such a method of measuring the thickness of the magnetic tape is based on the intensity of the fluorescent X-ray f ₁ detected by the first semiconductor detector on the front side of the magnetic tape and the second semiconductor detector on the back side of the magnetic tape. Since the film thickness is determined based on the intensity of the fluorescent X-ray f ₂ , the running magnetic tape flutters. For example, the magnetic tape moves away from the first X-ray tube and the first semiconductor detector, and the first semiconductor When the intensity of the fluorescent X-ray f ₁ detected by the detector decreases, the magnetic tape approaches the second X-ray tube and the second semiconductor detector, and the fluorescent X-ray detected by the second semiconductor detector. Since the intensity of f ₂ increases, the sum of the intensity detected by the first semiconductor detector and the intensity detected by the second semiconductor detector is the same as the sum of the intensity when the magnetic tape is not fluttered. Is equivalent to

According to a seventh aspect of the present invention, the primary X-ray x ₁ incident from the first X-ray tube and the primary X-ray x ₂ incident from the second X-ray tube are coaxial. By arranging the first X-ray tube and the second X-ray tube so as to face each other via a magnetic tape, and similarly, arranging the first semiconductor detector and the second semiconductor detector so as to face each other via a magnetic tape, , measured in the manner as the primary X-ray x ₁ is not incident to the second semiconductor detector passes through the magnetic tape, also the primary X-ray x ₂ is not incident to the first semiconductor detector passes through the magnetic tape Is the method.

Film thickness measuring method of the magnetic tape, the ones that has been transmitted through the magnetic tape of the primary X-ray x ₁ from the 1X-ray tube is incident on the second semiconductor detector, and from the 2X-ray tube Since the primary X-ray x ₂ that has passed through the magnetic tape is prevented from entering the first semiconductor detector, the counting capability in the portion that counts the intensity of the fluorescent X-ray f ₁ detected by the first semiconductor detector is increased. It does not saturate, and does not saturate the counting capability in the portion that counts the intensity of the fluorescent X-ray f ₂ detected by the second semiconductor detector.

According to the method of measuring the thickness of the magnetic tape of claim 8, the intensity of the fluorescent X-ray f ₁ generated according to the thickness of the magnetic layer or the nonmagnetic layer to which the target element is added is detected by the first semiconductor detector. The intensity of the fluorescent X-ray f ₁ is counted by a first counting circuit connected to the first semiconductor detector, and the intensity of the fluorescent X-ray f ₂ generated in the same way is detected by the second semiconductor detector. The intensity of the line f ₂ is counted by a second counting circuit connected to the second semiconductor detector, and in the measuring device to which the first counting circuit and the second counting circuit are connected, the count value of the fluorescent X-ray f ₁ In this method, a total value with the count value of the fluorescent X-ray f ₂ is obtained, and the thickness of the magnetic layer or the nonmagnetic layer is measured by comparing the total value with a calibration curve prepared in advance.

In such a magnetic tape film thickness measuring method, the total value of the count value of the fluorescent X-ray f ₁ by the first counting circuit and the count value of the fluorescent X-ray f ₂ by the second counting circuit is compared with the calibration curve. Thus, even if the magnetic tape fluctuates during running, the thickness of the magnetic layer of the magnetic tape can be accurately measured.

According to a ninth aspect of the present invention, there is provided a method for measuring the film thickness of the magnetic tape by synchronizing the counting of the fluorescent X-ray f ₁ in the first counting circuit and the counting of the fluorescent X-ray f ₂ in the second counting circuit.

Such a method for measuring the thickness of a magnetic tape causes the fluorescent X-ray f ₁ to be counted by the first counting circuit and the fluorescent X-ray f ₂ to be simultaneously counted by the second counting circuit on both sides of the same part of the magnetic tape. .

  The method for measuring the thickness of a magnetic tape according to claim 10 is characterized in that the first X-ray tube and the first semiconductor detector, and the second X-ray tube and the second semiconductor detector are integrated with the traveling magnetic tape. This is a method of reciprocating in the width direction.

In such a method of measuring the thickness of the magnetic tape, the primary X-ray x ₁ and the primary X-ray x ₂ are incident in a spot shape, so that the first X-ray tube and the second X-ray tube are not moved. Although the film thickness can be measured only at the linear portion in the running direction of the magnetic tape, the first X-ray tube and the first semiconductor detector, and the second X-ray tube and the second semiconductor detector are reciprocated in the width direction of the magnetic tape. Thus, the film thickness over the entire surface of the magnetic tape can be measured.

According to the film thickness measuring apparatus of the _{first aspect} , the intensity of the fluorescent X-ray f ₁ generated by the primary X-ray x ₁ from the first X-ray tube on the surface side of the magnetic tape can be detected by the first semiconductor detector. The intensity of the fluorescent X-ray f ₂ generated by the primary X-ray x ₂ from the second X-ray tube on the back side of the magnetic tape can be detected by the second semiconductor detector, and the running magnetic tape flutters. If, for example, the magnetic tape approaches the first X-ray tube and the first semiconductor detector and the intensity of the fluorescent X-ray f ₁ detected by the first semiconductor detector increases, the magnetic tape is away from the 2X-ray tube and the second semiconductor detector, the intensity of the fluorescent X-ray f ₂ detected by the second semiconductor detector is reduced, the fluorescent X-ray f ₁ detected by the first semiconductor detector According to strength and second semiconductor detector The sum of the intensities of the fluorescent X-ray f ₂ detected Te, the intensity of the fluorescent X-ray f ₁ of the first semiconductor detector when the magnetic tape does not occur flapping and fluorescent X-ray f by the second semiconductor detector _Since it is equivalent to the sum of the strengths of ₁ , it gives an accurate film thickness regardless of the flapping while the magnetic tape is running.

According to the film thickness measuring apparatus according to claim 2, prevents that passes through the magnetic tape of the primary X-ray x ₁ from the 1X-ray tube is incident on the second semiconductor detector, from the 2X-ray tube Of the primary X-ray x ₂ that has passed through the magnetic tape is prevented from entering the first semiconductor detector, so that the counting capability in the portion that counts the intensity of the fluorescent X-ray f ₁ detected by the first semiconductor detector Is not saturated, and the counting capability in the portion that counts the intensity of the fluorescent X-ray f ₂ detected by the second semiconductor detector is not saturated, so that it is not possible to accurately measure the film thickness. .

According to the film thickness measuring apparatus of the third aspect, the count value of the intensity of the fluorescent X-ray f ₁ by the first counting circuit and the count value of the intensity of the fluorescent X-ray f ₂ by the second counting circuit in the measuring apparatus. Since the total value is compared with the calibration curve prepared in advance, even if the magnetic tape flickers, it can be measured as the film thickness of the magnetic layer of the magnetic tape in a state where there is no flickering. .

  According to the film thickness measuring apparatus of claim 4, the counting by the first counting circuit and the counting by the second counting circuit are performed in synchronization, and the front and back of the same part of the magnetic tape are counted simultaneously. Even if the position of the film fluctuates, a highly accurate film thickness is always provided regardless of the position.

According to the film thickness measuring apparatus according to claim 5, since it is possible to reciprocate the incident spot of the primary X-ray x ₁ and primary X-ray x ₂ in the width direction of the magnetic tape traveling, over the entire surface of the magnetic tape film The thickness can be measured, and the film thickness distribution on the entire surface of the magnetic tape can be accurately known.

According to the film thickness measuring method according to claim 6, the intensity of the fluorescent X-ray f ₁ detected by the first semiconductor detector surface side of the magnetic tape is detected by the second semiconductor detector of the back side of the magnetic tape The film thickness can be obtained based on the intensity of the fluorescent X-ray f ₂ , and the running magnetic tape flickers. For example, the magnetic tape moves away from the first X-ray tube and the first semiconductor detector, and the first When the intensity of the fluorescent X-ray f ₁ detected by the semiconductor detector decreases, the magnetic tape approaches the second X-ray tube and the second semiconductor detector, and the fluorescent X-ray f ₂ generated by the second semiconductor detector. The intensity of the fluorescent X-ray f ₁ detected by the first semiconductor detector and the intensity of the fluorescent X-ray f ₂ detected by the second semiconductor detector cause the magnetic tape to flutter. the intensity and the fluorescence of the fluorescent X-ray f ₁ of the time and not It is equivalent to the sum of the intensities of the lines f _2, giving independent accurate thickness and fluttering in the magnetic tape running.

According to the film thickness measuring method according to claim 7, prevents that passes through the magnetic tape of the primary X-ray x ₁ from the 1X-ray tube is incident on the second semiconductor detector, from the 2X-ray tube Of the primary X-ray x ₂ that has passed through the magnetic tape is prevented from entering the first semiconductor detector, so that the counting capability in the portion that counts the intensity of the fluorescent X-ray f ₁ detected by the first semiconductor detector The film thickness can be measured with high accuracy without saturating the counter, and without saturating the counting capability in the portion for counting the intensity of the fluorescent X-ray f ₂ detected by the second semiconductor detector.

According to the film thickness measuring method according to claim 8, the count value of the fluorescent X-ray f ₁ by the first counting circuit and a count value of the fluorescent X-ray f ₂ according to the second counting circuit sums, create their sum in advance Therefore, even if the magnetic tape is fluttered, it can be measured as the film thickness of the magnetic layer of the magnetic tape in a state where there is no flutter.

According to the film thickness measuring method of the ninth aspect, the count of the fluorescent X-ray f ₁ by the first counting circuit and the count of the fluorescent X-ray f ₂ by the second counting circuit are synchronized, and the front and back of the same part of the magnetic tape are simultaneously Since counting is performed, even if the position of the magnetic tape fluctuates due to fluttering, a highly accurate film thickness is always provided regardless of the position.

According to the film thickness measuring method of the tenth aspect, since the incident spots of the primary X-ray x ₁ and the primary X-ray x ₂ are reciprocated in the width direction of the running magnetic tape, the film thickness can be measured on the entire surface of the magnetic tape. It is possible to know the state of film thickness distribution over the entire surface of the magnetic tape.

  FIG. 1 shows an X-ray tube and a semiconductor detector arranged on both sides of the front side and the back side of the magnetic tape T for measuring the film thickness of the magnetic layer 3 of the magnetic tape T shown in FIG. That is, it is a figure which shows the film thickness measurement part 10, 10 '. The nonmagnetic layer 2 of the magnetic tape T is mainly composed of fine powder of a nonmagnetic material such as α iron oxide, titanium oxide, carbon black and a binder, and the magnetic layer 3 is made of, for example, iron (Fe). It is mainly composed of a magnetic material and a binder added with a small amount of a target element that generates fluorescent X-rays specific to the ferromagnetic metal powder as a main component. As the target element, chromium, aluminum, titanium, silicon oxide, silicon nitride, silicon carbide, and others are generally used. As the binder, generally, a vinyl chloride copolymer resin is mainly used and a crosslinkable polyurethane resin is mixed with this.

The primary X-ray x ₁ from the X-ray tube 4 is incident on the magnetic tape T at a predetermined incident angle on the surface side of such a magnetic tape T, and the target element contained in the magnetic layer 3 forms the magnetic layer 3. The intensity of the fluorescent X-ray f ₁ generated according to the film thickness is detected by the semiconductor detector 11 arranged in the direction of the reflection angle corresponding to the incident angle of the primary X-ray x ₁ and connected to the semiconductor detector 11. At the same time that the intensity of the fluorescent X-ray f ₁ is counted by the counting circuit 13, an X-ray tube 5 is arranged on the back side of the magnetic tape T so as to face the X-ray tube 4 on the front side, and the X-ray tube a primary X-ray x ₂ from 5 to magnetic tape T is incident at a predetermined incident angle, the intensity of the fluorescent X-ray f ₂ generated in response from the target element contained in the magnetic layer 3 in the thickness of the magnetic layer 3 in the semiconductor detector 12 which is arranged in the direction of the reflection angle corresponding to the angle of incidence of the primary X-ray x ₂ Out by counting the intensity of the fluorescent X-ray f ₂ by the counting circuit 14 connected to the semiconductor detector 12 is a device which is to obtain the thickness of the magnetic layer 3.

  That is, when the distance g between the magnetic tape T and the film thickness measuring unit 10 decreases, the intensity of the detected fluorescent X-ray f increases, and when the distance g increases, the detected intensity of the fluorescent X-ray f decreases. Therefore, by arranging the X-ray tube 4 and the semiconductor detector 11 on the front surface side of the magnetic tape T, and the X-ray tube 5 and the semiconductor detector 12 on the back surface side, fluorescence due to fluttering of the traveling magnetic tape T is obtained. This is an apparatus that can offset fluctuations in the intensity of X-rays f on the front and back sides, and can accurately measure the film thickness of the magnetic layer 3 regardless of the flutter of the magnetic tape T.

As shown in FIG. 1, the X-ray tube 4 and the X-ray tube 5, and the semiconductor detector 11 and the semiconductor detector 12 are arranged to face each other from the X-ray tube 4 on the surface side. This is to prevent the transmission of the next X-ray x ₁ magnetic tape T from entering the semiconductor detector 12 on the back side and saturating the ability of the counting circuit 14 connected to the semiconductor detector 12. The transmission of the primary X-ray x ₂ magnetic tape T from the X-ray tube 5 enters the semiconductor detector 11 on the surface side, and the capacity of the counting circuit 13 connected to the semiconductor detector 11 is saturated. This is to prevent this.

  The energy dispersive semiconductor detector 11 to be used converts the intensity of fluorescent X-rays energetically by a semiconductor having a PIN junction obtained by diffusing Li (lithium) into P-type Si (silicon) and converts it into a current pulse. The counting circuit 13 counts the pulse height of the current pulse as the intensity of the fluorescent X-ray, and since the scintillation counter tube or the photomultiplier tube is not used, the apparatus becomes small in size and is frequently used. In the present invention, a silicon drift detector (SDD) having excellent detection performance is used among semiconductor detectors. SDD efficiently guides electrons generated from P-type Si to the anode of a concentric electrode structure, and converts a detected current pulse into a voltage pulse by a built-in electric circuit.

  The counting circuits 13 and 14 count the pulse height of the voltage pulse from the SDD as the energy intensity of the fluorescent X-ray, but can count the voltage pulse at a high speed so as not to cause a counting leak. By using a digital signal processing substrate (DSP substrate) having a counting rate that can count at least 100 kcps at a minimum, the film thickness of the magnetic layer 3 can be measured with high accuracy in a short time. Can do.

FIG. 2 is a block diagram showing a configuration of the film thickness measuring apparatus 1 having the X-ray tube 4 and the semiconductor detector 11 and the X-ray tube 5 and the semiconductor detector 12 shown in FIG. Voltages are applied to the X-ray tubes 4 and 5 to which primary X-rays are incident from high-voltage power supplies 6 and 7, respectively. The high-voltage power supplies 6 and 7 are generated by the control device 8 on the X-ray tubes 4 and 5. Controls primary X-ray output. The generated primary X-rays are incident on the magnetic tape T in a spot shape, but the magnetic tape T on which the magnetic film 3 is formed is wide, so that the state of the film thickness distribution over the entire magnetic tape T is known. Therefore, the width direction of the magnetic tape T that travels the incident spot of the primary X-ray x ₁ from the X-ray tube 4 and the incident spot of the primary X-ray x ₂ from the X-ray tube 5 to the magnetic tape T. To reciprocate. For this purpose, the X-ray tube 4 and the semiconductor detector 11 on the front surface side, and the X-ray tube 5 and the semiconductor detector 12 on the back surface side are reciprocated in the width direction as one body, but the same as the motor 10 for the traverse operation. A motor control device 9 is provided.

And the intensity | strength of the fluorescent X-ray detected by the semiconductor detectors 11 and 12 is counted for every energy by the counting circuits 13 and 14 connected to each. The film thickness measuring device 15 takes in the pulse counts at regular intervals in the counting circuits 13 and 14 in synchronism, adds the count values of the counting circuits 13 and 14 as shown in the following equation (1), and calculates the total value. Contrast with the calibration curve prepared in advance and displayed as a film thickness.
Total value of count in film thickness measuring device 15 = count value of counting circuit 13 + count value of counting circuit 14 Equation (1)
At this time, since the counting by the counting circuit 13 and the counting by the counting circuit 14 are synchronized, even if the position of the magnetic tape at the measurement location fluctuates due to the flapping of the magnetic tape, the film thickness of the magnetic layer 3 is independent of the position. Can be measured with high accuracy.

A PET film having a thickness of 12 μm is used as the base film B, and the non-coating paint 22 is first applied to the surface of the traveling base film B by the die 21N, which is conceptually shown in FIG. In the magnetic tape T manufacturing process in which the magnetic coating 24 is applied onto the coating film of the magnetic coating 22 by the die 23M and then dried (wet-on-wet method), the film is formed immediately after the coating is dried. The thickness of the magnetic layer 3 on the nonmagnetic layer 2 was measured. In the above, a powder of α-iron oxide (α-Fe ₂ O ₃ ) is used as the nonmagnetic material, a powder of Fe-based metal ferromagnetic material is used as the magnetic material, and the target element added to the ferromagnetic material is used. Adopted yttrium (Y), which is used to prevent oxidation of Fe-based metal ferromagnetic materials. As the binder, a material mainly composed of the above-described vinyl chloride copolymer resin was used for both the nonmagnetic layer 2 and the magnetic layer 3. The above-mentioned paint is obtained by dispersing fine powder of a nonmagnetic material or fine powder of a magnetic material in a solution obtained by dissolving a binder in an organic solvent.

Four types of magnetic tape samples A, B, C, and D having different thicknesses of the magnetic layer 3 were prepared by the above-described die coating method. The film thickness measuring apparatus 1 shown in FIG. 1 shows the count value [cps] of the intensity of the fluorescent X-ray f ₁ by the semiconductor detector 11 on the front and back of the magnetic tape T and the fluorescent X-ray f ₂ by the semiconductor detector 12. The intensity count value [cps] and the film thickness measured by observing a thin piece obtained by chopping each of the samples A, B, C, and D in the thickness direction with an ultra-microtome with a transmission electron microscope (TEM) Are shown in Table 1 and Table 2. The relationship between them is shown in FIG. As shown in FIG. 4, it was confirmed that there was a correlation that could be converted with a calibration curve between the measured value by TEM and the count value of the intensity of fluorescent X-rays by Y as the target element.

The total value [cps] of the count value of the intensity of the fluorescent X-ray f ₁ by the semiconductor detector 11 on the front and back of the samples A, B, C, and D and the count value of the intensity of the fluorescent X-ray f ₂ by the semiconductor detector 12. Table 3 and FIG. 5 show the relationship between the film thickness measured by TEM and the film thickness. There is a substantial merit that a single calibration curve can be used by measuring the film thickness by the combined value.

  The method for measuring the thickness of the magnetic tape according to the present invention has been described above by way of example, but the present invention is of course not limited thereto, and various modifications can be made based on the technical idea of the present invention.

  For example, in this embodiment, the target element is added to the magnetic layer 3 and the film thickness of the magnetic layer 3 is obtained based on the intensity of fluorescent X-rays generated by the target element. It is also possible to obtain the film thickness of the nonmagnetic layer 2 by adding elements.

  In the present embodiment, the case where the film thickness of the upper magnetic layer 3 to which the target element of the magnetic tape T having a two-layer structure is added is described. However, as described in Patent Document 1, the target element is used. Thus, the method of measuring the film thickness has the advantage that the film thickness of the multiple layers to which the target element is added can be measured simultaneously by adding different types of target elements to any multiple layers of the multilayer structure. is doing. The film thickness measuring apparatus and film thickness measuring method of the present invention can also be applied when measuring the film thickness of a plurality of layers at the same time for such a multilayer magnetic tape.

In this embodiment, α-iron oxide (α-Fe ₂ O ₃ ) is used as the material of the nonmagnetic layer 2, and an Fe-based metal ferromagnetic material is used as the material of the magnetic layer 3. Since the magnetic layer 3 contains Fe, since the film thickness of the magnetic layer 3 cannot be measured by fluorescent X-rays generated by Fe, the target element Y is added to the magnetic layer 3. When a material that does not contain Fe, for example, titanium oxide or carbon black, is used as the material of the nonmagnetic layer 2, it is generated from the Fe-based metal ferromagnetic material of the magnetic layer 3 without adding a target element to the magnetic layer 3. The film thickness can be measured by fluorescent X-rays. Even in such a case, the film thickness measuring apparatus and the film thickness measuring method of the present invention can be applied.

It is a figure which shows arrangement | positioning with the semiconductor detector for detecting the X-ray tube and fluorescence X-ray in the measuring apparatus used for the film thickness measurement of the magnetic film of the magnetic tape in an Example. It is a block diagram which shows the whole structure of the measuring device. It is a figure which shows notionally the method of the die coating which apply | coats a nonmagnetic coating material and a magnetic coating material to a base film. It is a figure which shows the relationship between the count value of the intensity | strength of the fluorescent X-ray detected by the semiconductor detector of the surface side of a magnetic tape, and the thickness of the magnetic film measured with the transmission electron microscope. It is a figure which shows the relationship between the total value of the count value by the semiconductor detector of the surface side, and the count value by the semiconductor detector of the back surface side, and the thickness of the magnetic film measured with the transmission electron microscope. It is a perspective view which shows the magnetic tape of the two-layer structure which formed the lower nonmagnetic layer and the upper magnetic layer in the base film. The primary X-ray is made incident on the magnetic layer of the magnetic tape from the X-ray tube, and the thickness of the magnetic layer is measured by detecting the intensity of the fluorescent X-ray generated from the target element contained in the magnetic layer with a semiconductor detector. It is a figure which shows a method in model. In the measuring method of FIG. 7, when a roll exists in the back surface of a magnetic tape, it is a figure which shows that the fluorescent X-rays generate | occur | produced from a roll are counted simultaneously. In order to avoid the state as shown in FIG. 8, the measurement of the film thickness by fluorescent X-rays is performed at a place where there are no rolls on the back side of the magnetic tape. As shown in FIG. 9, when the film thickness is measured between the rolls by fluorescent X-rays, the magnetic tape flickers even if there is a slight difference, and the distance between the magnetic layer and the semiconductor detector is determined. It is a figure which shows that it is detected by, but it fluctuates and an accurate measurement cannot be performed. It is a figure which shows the relationship between the fluctuation | variation of the distance between the magnetic layer and semiconductor detector by the flapping of a magnetic tape, and the intensity | strength of the fluorescent X-ray detected by a semiconductor detector.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Film thickness measuring apparatus, 2 ... Nonmagnetic layer, 3 ... Magnetic layer,
4 ... X-ray tube, 5 ... X-ray tube, 10 ... Film thickness measuring part,
DESCRIPTION OF SYMBOLS 11 ... Semiconductor detector, 12 ... Semiconductor detector, 13 ... Counting circuit, 14 ... Counting circuit, 15 ... Measuring device, 21 ... Die N,
22 ... Non-magnetic paint, 23 ... Die M, 24 ... Magnetic paint,
B ... base film, f ... fluorescent X-ray, T ... magnetic tape,
x ... Primary X-ray,

Claims (10)

Applying the coating of the non-magnetic layer on the surface of the traveling plastic film, applying the coating of the magnetic layer thereon without drying, and then drying both of the magnetic layer of the magnetic tape or In the magnetic tape film thickness measurement device that measures the film thickness of the nonmagnetic layer in-line immediately after drying,
A first X-ray tube that enters primary X-ray x ₁ at a predetermined incident angle toward the magnetic tape on the surface side of the magnetic tape, and the primary X-ray x ₁ are received, and the magnetic layer or the non-magnetic layer A first semiconductor detector for detecting fluorescent X-rays f ₁ generated from a target element previously added to the magnetic layer is disposed in a direction of a reflection angle corresponding to the incident angle;
And, on the back side of the magnetic tape, a second X-ray tube that enters the primary X-ray x ₂ at a predetermined incident angle toward the magnetic tape and the primary X-ray x ₂ are received from the target element. A magnetic tape film thickness measuring apparatus, wherein a second semiconductor detector for detecting the generated fluorescent X-ray f ₂ is arranged in a direction of a reflection angle corresponding to the incident angle. The first X-ray tube and the primary X-ray x ₁ incident from the first X-ray tube and the primary X-ray x ₂ incident from the second X-ray tube are coaxial. A second X-ray tube is disposed opposite to the magnetic tape, and similarly, the first semiconductor detector and the second semiconductor detector are disposed opposite to each other via the magnetic tape. The apparatus for measuring a thickness of a magnetic tape according to claim 1. The fluorescence X detected by the first semiconductor detector according to the film thickness of the magnetic layer or the nonmagnetic layer to which the target element is added and counted by a first counter circuit connected to the first semiconductor detector. An intensity count value of the line f _{1, and} an intensity count value of the fluorescent X-ray f ₂ detected by the second semiconductor detector and counted by a second counting circuit connected to the second semiconductor detector. A measuring device that calculates a sum value and measures the film thickness of the magnetic layer or the nonmagnetic layer by comparing the sum value with a calibration curve prepared in advance is connected to the first count circuit and the second count circuit. 3. The film thickness measuring device for a magnetic tape according to claim 1, wherein the thickness measuring device is a magnetic tape. The film thickness of the magnetic tape of claim 3 in which the first counting circuit according to the fluorescent X-ray f ₁ count and the count of the fluorescent X-ray f ₂ of the second counting circuit is characterized in that it is counted in synchronization measuring device.   The width of the magnetic tape perpendicular to the traveling direction, in which the first X-ray tube and the first semiconductor detector, and the second X-ray tube and the second semiconductor detector are integrated with the traveling magnetic tape. The magnetic tape film thickness measuring device according to any one of claims 1 to 4, wherein the magnetic tape film thickness measuring device is installed so as to be capable of reciprocating in a direction. Applying the coating of the non-magnetic layer on the surface of the traveling plastic film, applying the coating of the magnetic layer thereon without drying, and then drying both of the magnetic layer of the magnetic tape or In the method of measuring the thickness of the magnetic tape, measuring the thickness of the nonmagnetic layer in-line immediately after drying,
A primary X-ray x ₁ is incident at a predetermined incident angle from a first X-ray tube disposed on the surface side of the magnetic tape toward the magnetic tape, receives the primary X-ray x _1, and receives the primary X-ray x _1. Fluorescent X-rays f ₁ generated from a target element added in advance to the nonmagnetic layer are detected by a first semiconductor detector disposed in the direction of the reflection angle corresponding to the incident angle on the surface side of the magnetic tape,
At the same time, a primary X-ray x ₂ is incident at a predetermined incident angle from a second X-ray tube disposed on the back side of the magnetic tape toward the magnetic tape, receives the primary X-ray x _2, and receives the target element. Fluorescent X-rays f ₂ generated from the magnetic tape are detected by a second semiconductor detector disposed on the back side of the magnetic tape in the direction of the reflection angle corresponding to the incident angle,
The magnetic layer or the nonmagnetic layer based on the intensity of the fluorescent X-ray f ₁ detected by the first semiconductor detector and the intensity of the fluorescent X-ray f ₂ detected by the second semiconductor detector A method for measuring the thickness of a magnetic tape, comprising measuring the thickness of the magnetic tape. The first X-ray tube and the primary X-ray x ₁ incident from the first X-ray tube and the primary X-ray x ₂ incident from the second X-ray tube are coaxial. By arranging the second X-ray tube so as to face each other through the magnetic tape, and similarly arranging the first semiconductor detector and the second semiconductor detector so as to face each other via the magnetic tape, The primary X-ray x ₁ does not pass through the magnetic tape and enter the second semiconductor detector, and the primary X-ray x ₂ does not pass through the magnetic tape and enter the first semiconductor detector. The method of measuring a film thickness of a magnetic tape according to claim 6, wherein the measurement is performed as follows. The intensity of the fluorescent X-ray f ₁ generated according to the film thickness of the magnetic layer or the nonmagnetic layer to which the target element is added is detected by the first semiconductor detector, and the detected fluorescent X-ray f ₁ The intensity is counted by a first counting circuit connected to the first semiconductor detector, the intensity of the generated fluorescent X-ray f ₂ is detected by the second semiconductor detector, and the detected fluorescent X-ray f ₂ is detected. Is counted by a second counting circuit connected to the second semiconductor detector, and in the measuring device to which the first counting circuit and the second counting circuit are connected, the count value of the fluorescent X-ray f ₁ And the count value of the fluorescent X-ray f ₂ is obtained, and the film thickness of the magnetic layer or the nonmagnetic layer is measured by comparing the total value with a calibration curve prepared in advance. Claim 6 or Claim 7 Care tape thickness measurement method. The magnetic tape of claim 8, wherein the count of the fluorescent X-ray f _1, counting in synchronism with the count of the fluorescent X-ray f ₂ in the second counter circuit in said first counting circuit Film thickness measurement method. The first X-ray tube and the first semiconductor detector, and the second X-ray tube and the second semiconductor detector are integrally reciprocated in the width direction of the magnetic tape with respect to the traveling magnetic tape. A method for measuring a film thickness of a magnetic tape according to any one of claims 6 to 9, wherein:

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