JPH083521B2 - Magnetic thin film magnetization characteristic measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a magnetic property for accurately measuring the magnetic property of a magnetic thin film such as a magnetic stripe of a magnetic tape or a magnetic card, or a magnetic disk. Regarding measuring device.

(Prior Art) With the progress of the information society, magnetic cards, magnetic tapes and magnetic disks as data recording media have already become a large market, but it is easy to predict that they will further develop in the future. . In order for these media to be produced in large quantities, stably, and at low cost, further progress in research and development and improvement in quality level are required. Media is one of the means to support these A device is used to measure the magnetization characteristics of. For example, as a device for recording the magnetization characteristic of a magnetic thin film such as a magnetic tape, there is currently a 3257 type DC magnetization characteristic automatic recording device manufactured by Yokogawa Electric Co., Ltd.
Riken Denshi Co., Ltd. BHS-40, BHH-50, BHU-60 type DC magnetization BH characteristic automatic recording device and the like have been commercialized.

Here, as an example of the detection method in the above device,
First, a general method for detecting the magnetization characteristic of the annular material will be described. When the magnetic field H is applied to the magnetic body to be measured, the amount of magnetic flux Φ generated in the magnetic body changes depending on this magnitude. A graph in which the magnetic field H is plotted on the horizontal axis and the magnetic flux Φ is plotted on the vertical axis is called a magnetization curve (hysteresis loop). This magnetization curve is generally obtained by the configuration shown in FIG. . That is, the annular magnetic body 100
The magnetizing coil 101 is wound around the primary side of the
N ₁ ) The detection coil 102 is wound around the secondary side (the number of turns N
₂ ). Then, a low-frequency sine wave is applied to the magnetizing coil 101 from the low-frequency oscillator 103, and the resistor R ₁ is inserted in series.

Here, since the magnetic field H in the magnetic body 100 can be considered to be proportional to the current I ₁ flowing in the magnetizing coil 101, let the magnetic path length of the magnetic body 100 be l. Becomes On the other hand, the generated magnetic flux Φ is obtained by integrating the output voltage V ₂ of the detection coil 102. That is, the output voltage V _C is Because Becomes A magnetization curve (Φ-H curve) is obtained by measuring such voltages V ₁ and V _C. Further, when the voltage V ₂ is plotted on the vertical axis, an output proportional to magnetic permeability can be obtained.

The operation of the magnetic substance measuring device based on such a principle is 19
It is described on pages 49 to 72 of "Yokogawa Technical Report Vol.17 No.2" published in 1973.

(Problems to be Solved by the Invention) Although the above-mentioned measuring device has versatility for measuring high magnetic permeability materials, plates such as permanent magnets, block materials, magnetic powders, magnetic thin films, etc., it has functions and operability. ， There is a difficulty in price. Further, in the above measuring device, for example, a magnetic stripe formed by thermal transfer or application to a paper card, a card or passbook to which a magnetic tape is attached, the measurement of the magnetization characteristics of a magnetic card having a surface coated, It was very troublesome to cut out the magnetic thin film from a card or the like and prepare for a certain size in terms of the structure of the device, and to use a sample 110 having a thickness of about 10 sheets as shown in FIG. Further, it has been impossible to measure the magnetization characteristics of a magnetic stripe of a magnetic card or the like in a state in which the magnetic card is layered. Further, in order to judge the quality of the magnetization characteristic, the user visually checks the magnetization characteristic values such as saturation magnetic flux, residual magnetism and coercive force from the hysteresis curve once drawn on the paper surface with an XY recorder equipped with the device. It was very time-consuming to read and calculate and make decisions. In addition, there is a problem that there is no measuring instrument capable of analyzing the process capability of the magnetization characteristic value. Further, in the currently commercialized device, for example, the excitation amplification section, the signal processing integrator, the XY recorder and the like are combined as individual devices, and there is a drawback that the device itself becomes extremely large. is there.

Japanese Patent Publication No. 46-3143 discloses an apparatus for measuring the magnetic characteristics of a magnetic sheet having a large area without cutting the sheet or cutting the sheet. This device uses the differential output of two magnetic heads, but it is practically impossible to completely match the characteristics of these two magnetic heads, that is, the detection head and the cancel head, so the sample There is a drawback that an unbalanced component is added in addition to the signal. In addition, there is a drawback that the data includes leakage magnetic flux from the periphery of the gap portion, resulting in data that apparently does not saturate the hysteresis loop of the sample.

The present invention has been made in view of the above problems, and an object of the present invention is to physically destroy the magnetization characteristics of a magnetic thin film such as a magnetic tape, a magnetic stripe, and a magnetic disk by cutting off a magnetic tape of a sample. An object of the present invention is to provide a magnetization characteristic measuring device capable of performing measurement without bending or deformation. Moreover, it is an object of the present invention to provide a measuring device capable of accurately measuring the magnetization characteristic value by correcting the leakage magnetic flux in the gap portion.

Structure of the Invention: (Means for Solving the Problems) The present invention relates to a highly accurate magnetization characteristic measuring device, and the above object of the present invention is to provide a differential magnetic head and a triangular wave signal for the differential magnetic head. From the side surface of the head outside the gap part of the differential magnetic head, the triangular wave signal generating means for exciting the differential magnetic head, the measurement data converting means for sampling the differential output voltage of the differential magnetic head and converting it into a digital value. Storage means for storing the correction coefficient α for correcting the influence of the leakage flux of the magnetic field, and the digital value for the magnetic thin film to be measured are sequentially input, and the measurement is performed based on the correction coefficient α stored in the storage means. This is achieved by including measurement data analysis means for correcting and calculating the magnetization characteristic value of the magnetic thin film to be formed. Further, the correction coefficient α stored in the storage means in advance is obtained as follows. When the difference Δμ (i) between the magnetic field H and the magnetic susceptibility μ characteristic is obtained between the normal sample and the band-shaped sample of the magnetic thin film, and the integrated average value of all the sampling points of Δμ (i) is μL, μL / μm
Is the correction coefficient α. Further, regarding the magnetization characteristics of the magnetic thin film to be measured, when the positive and negative peak values of the magnetic field H vs. magnetic susceptibility μ characteristics are set to ▲ μ ⁺ _m ▼, ▲ μ ⁻ _m ▼, μ _m = (▲ μ ⁺
as _m ▼ _{-μ m)} / 2, when the μ ≧ 0 μ '= μ- α ·
When μ _m and μ <0, the correction coefficient α is corrected by μ ′ = μ + α · μ _m , and the correction coefficient α is set to the sharpness Q of the magnetic field H versus magnetic susceptibility μ characteristic of the normal sample. gamma, as [delta], alpha = or corrected by γQ-δ, and the boundary of the peak position H _m α ₁ · _{μ m,} are modified as α ₂ · μ _m.

(Operation) According to the present invention, the differential magnetic head of the magnetic measuring unit is moved to a position on or near the magnetic thin film, and then a triangular wave signal is applied, and the differential output voltage of the differential magnetic head is applied to the data converting unit. It is converted into digital signal data, and the measured data analysis unit calculates the magnetization characteristic value by software integration based on this data. Furthermore, based on this magnetization characteristic calculation result, the quality of the magnetization characteristic of the magnetic thin film is determined. I am trying to judge. Further, since the leakage magnetic flux is corrected and measured at the time of actually measuring the magnetization characteristic, it is possible to measure the magnetization characteristic with high accuracy.

(Embodiment) FIG. 1 shows an external configuration of a magnetization characteristic measuring apparatus 80 according to an embodiment of the present invention. In this magnetization characteristic measuring device (hereinafter, simply referred to as a measuring device) 80, a magnetic card or the like on which a magnetic thin film is layered, or a table 82 on which a belt-like sample described below is inserted and placed is placed on the left side of the front panel. A marker 83 for positioning the measuring portion of the magnetic thin film such as a magnetic card is provided above the table 82 so as to be movable back and forth. Further, above the marker 83, a vertically movable holding arm 81 for fixing a magnetic card or the like placed on the table 82 and the magnetic head 1 for reading magnetic characteristics are provided. When a separate operation button is pressed when the positioning of the magnetic card or the like is completed, the holding arm 81 descends in the direction of arrow N to fix the magnetic card or the like. After reconfirming the position of the measuring section with the marker 83, when the operation button is pressed separately, the marker 83 is taken in and housed in the direction of the arrow M, the magnetic head 1 moves in a predetermined direction, and the vertical line of the marker 83 moves. It is located in the measuring portion of the magnetic thin film shown by (4) and measures the magnetization characteristics of the magnetic thin film. A keyboard 29 having a numeric keypad for inputting operation procedures and necessary data is provided on the right side of the panel, and measurement items of the magnetization characteristics of the magnetic thin film are displayed on the upper left side of the panel surface. A display 68 is provided. Furthermore, the measuring device
A power switch 84 is provided below the right side panel of 80.

FIG. 2 shows a circuit system of the measuring device 80 in a block configuration. This circuit system includes a magnetic measuring unit 20 for measuring the magnetization characteristics of a magnetic thin film such as a magnetic tape and a voltage measured by the magnetic measuring unit 20. The measurement data conversion unit 21 that converts the signal V _D into a digital signal or generates the triangular wave signal SD2 that drives the magnetic measurement unit 20, and the digital signal converted by the measurement data conversion unit 21 as computer processing are used as magnetization characteristic values. And a measurement data analysis unit 60 having functions of determining whether the magnetization characteristic is good or not, self-diagnosis, and the like.

The magnetic measurement unit 20 is provided with a vertically and horizontally symmetrical H-shaped magnetic head 1, and the magnetic core of the magnetic head 1 has primary coils 2 and 3 connected in series with a winding number N _1. Is wound, and the secondary coils 4 and 5 having the number of turns N ₂ are separately wound. A low-frequency triangular wave signal SD2 of about 1 to 10 Hz is input from the measurement data converter 21 to the primary coils 2 and 3 via an amplifier 19. The frequency of the triangular wave signal SD2 can be up to several MHz. A gap portion 1A on the detection side is provided below the magnetic core 1, and a gap portion 1B on the non-detection side is provided above the magnetic core 1. Two
The output voltage V _S of the secondary coil 4 is obtained via the amplifier 10 and
The output voltage V _SC of the secondary coil 5 is obtained via the amplifier 11,
The output voltages V _S and V _SC are input to the differential amplifier 12.
Here, each gain of the amplifiers 10 to 12 is set to "1" for convenience.

Here, the measurement principle of the magnetic head will be described. First, the cross-sectional area of the magnetic core 1 of the coil portion is S, the magnetic core cross-sectional area of the gap portion 1A is S _g , the core magnetic path length is l, the gap length is l _g , the magnetic permeability of the magnetic core is μ, and the air permeability is Let the magnetic susceptibility be μ _o .

Magnetic flux Φ with no medium in contact with the gap 1A
Is the magnetic resistance of the magnetic core 1 R (= l / μS) , the magnetic resistance of the gap portion 1A and _{R g (= l g / μ} o S g), And the magnetic field Hg of the gap 1A is Is. here, Then, the relationship between the magnetic field Hg and the current I is Becomes

Next, due to the relationship of the magnetic resistance R << R _g , the magnetic flux Φ has a spread in the gap portion 1A as shown in FIG. 3, and a part of the magnetic flux apparently has a gap length l in the magnetic thin film 200.
_{It is almost} parallel to the direction of _g . If the magnetic flux when the magnetic thin film 200 is connected to the gap 1A is Φ ₁ , the electromotive voltage V _S of the secondary coil 4 is , And the electromotive voltage V _SC of the secondary coil 5 of the non-detection side when the magnetic flux and [Phi _C, Becomes Therefore, the output voltage V _D of the differential amplifier 12 is (7)-
From equation (9), when there is no magnetic thin film 200, And when there is a magnetic thin film 200, Becomes The magnetic flux Φ monotonically increases or decreases monotonically because the low frequency triangular wave SD2 is applied to the primary coils 2 and 3 from the measurement data converter 21. Such a differential amplifier 12
Output voltages V _D and V _D1 of the RAM 62 and 63 are converted by the measurement data conversion unit 21 and taken into the measurement data analysis unit 60 and stored in the RAMs 62 and 63 of the memory unit 61. , 63
By reading the data and taking the difference between the expressions (10) and (11), the output voltage V _D ′ based on the increment of the magnetic flux Φ due to the setting of the magnetic thin film 200 can be calculated.

Then, assuming that the cross-sectional area of the magnetic thin film 200 is S ₁ (= thickness d × width W), the magnetic flux density B _{1 at} this portion is Φ ₁ −Φ = Φ ′ = B ₁ · S ₁ ……… (13 ), And from equation (12) Is.

The magnetic permeability μ ₁ of the magnetic thin film 200 (accurately, the magnetic susceptibility is x, and μ ₁ = x = μ ₁ ′ −1, μ ₁ ′ is the true magnetic permeability) is Becomes Software integration is performed by adding the data at each magnetic field strength in equation (12). That is, Because Becomes Here, Δt is a sampling cycle, and the addition is for one cycle of the applied magnetic field H.

Here, the above software integration will be explained. The characteristic I of FIG. 4 is that the voltage V _D ′ according to the equation (12) with respect to the magnetic field H is obtained.
Of the characteristic I, and an arbitrary point in the characteristic I is represented by v _i . Next, the following integral value Ψ is obtained from this initial value v _i using the data sampling period ΔH.

Therefore, the value Ψ _{i + n} corresponding to the magnetic flux Φ _{i + 1} is an integrated value with respect to the horizontal axis H (magnetic field). This characteristic is indicated by II in FIG. That is, when the characteristic I of FIG. 4 is integrated from v _i , the curve of the characteristic II is obtained. The magnetic flux Φ ′ can be obtained by making the following corrections.

Here, Ψ _i and Ψ _{i + a} are values symmetrical with respect to the center of gravity of the magnetization curve. Note that Ψ _i does not necessarily have to be an initial value of integration, and may be a symmetric value of the center of gravity. Here, n represents an integer counted from the initial value i for each sampling period ΔH.

When a magnetization curve is drawn with the magnetic field H and the magnetic flux Φ'obtained as described above, a curve obtained by shifting the characteristic II in the vertical axis direction is obtained as shown in FIG.

Here, in the H-Φ ′ characteristic of the magnetic thin film as shown in FIG. 3, that is, the magnetic thin film (normal sample) having a detection region wider than the gap length l _g of the tip of the magnetic head 1,
The magnetic flux .PHI. 'Tends not to be saturated with respect to the magnetic field H as shown in FIG. On the other hand, as shown in Fig. 6, the gap length lg
In the case of the magnetic thin film 200A (hereinafter, referred to as a band-shaped sample) having a width w that is almost the same as the above, saturation is likely to occur as shown by the characteristic A in FIG. This is because in the case of a normal sample, it is considered that the leakage magnetic flux LF is generated from the side surface of the gap portion as shown in FIG. That is, the magnetic field H at the position x in the magnetic thin film 200 in the model diagram of FIG. 7 has a distribution as shown in FIG. 8 when normalized by the magnetic field H _o at the center of the gap. Here, the magnetic field H converted from the above-mentioned primary side current I is the magnetic field at the center of the gap.
Although H _o is shown, in the case of a normal sample, magnetic fields HL and HL ₂ much smaller than the magnetic field H _o are applied in places other than the gap as shown in FIG. This is the magnetic field H
When expressed by the magnetic susceptibility μ, the characteristics shown in FIG. 9 are obtained (the value V _D ′ before integration for obtaining Φ in the equation (17) is the magnetic susceptibility μ ₁ as is clear from the equation (15). The magnetic susceptibility μ is used instead of V _D ′ for convenience sake below). The characteristic is the response to the magnetic field H _o , and the characteristic is the magnetic field HL
_The response to ₁ and the characteristic to the magnetic field HL ₂ are shown. That is, the magnetic susceptibility μ due to the regular magnetic field H _o
Magnetic field HL ₁ , HL even in the region (current value) where is almost zero
_The magnetic thin film 200 continues to be magnetized by ₂ etc., and the response (increased amount of magnetic flux) of that amount is detected from the secondary coil 4 of the magnetic head 1. In the case of the band-shaped sample 200A, the data of only the characteristics shown in FIG. 9 is obtained, but in the case of the normal sample, the data in which the characteristics and the like are superposed are obtained.

In order in the Figure 9 for clarity of explanation, although a peak of the substantially HL _1, HL ₂ is ,, the peak much smaller than in the H _o in FIG When mu> 0 Far to the right, far to the left when μ <0, and such a peak does not appear within the normal measurement range. further,
To mention, the amount of leakage magnetic flux superposed, such as, is the form in which the characteristic near H≈0 in the figure (marked with a circle in the figure) is expanded to the full range in the horizontal direction and reduced in the vertical direction, Therefore, from equation (15), V _D ′ corresponding to HL ₁ and HL ₂ is H _o
It is considered that the response component due to these leakage magnetic fluxes is substantially constant regardless of the magnetic field H, with a slight upward-sloping slope, because it is much smaller than that due to.

According to the present invention, the influence of the leakage magnetic flux is removed so that the magnetization characteristic of a normal sample can be accurately measured. In the present invention, the normal sample 200A and the band-shaped sample 200A are
The μ-H characteristic shown in FIG. 10 is obtained. In FIG.
The characteristic of the normal sample 200 is the curve B, and the characteristic of the band-shaped sample 200A is the curve C. If the difference Δμ (i) = B−C between them is taken, it is almost independent of the magnetic field H as shown by the characteristic D in FIG. Becomes a constant value μL. That is, the magnetic susceptibility μ of the normal sample 200 is obtained by offsetting μL from the band-shaped sample 200A, and μL corresponds to the leakage magnetic flux LF from other than the gap portion. Then, when the μL / μm value of various samples having different materials and thicknesses is calculated with respect to the peak value μm of the measurement data,
As shown in Table 1 below, the value is almost constant regardless of the material and thickness, that is, about 0.04 for the magnetic material γ-Fe ₂ O ₃ and about 0.06 for the magnetic material CrO ₂ .

However, μm = (▲ μ ⁺ _m ▼ − ▲ μ ⁻ _m ▼) / 2 μL is the integrated average value of all sampling points of Δμ (i).

From the above results, in order to correct the leakage magnetic flux LF, if the corrected data is μ ′ with respect to the uncorrected raw data μ, the offset μL may be added or subtracted, so μL / μm = α is used as the correction coefficient μ When ≧ 0 μ ′ = μ−α · μm (20) (However, if μ ′ <0, μ ′ = 0) When μ <0 μ ′ = μ + α · μm …… (21 ) (However, if μ ′> 0, μ ′ = 0). Here, taking the ▲ mu ⁺ _m ▼ and ▲ [mu] m _^▼ mean value in order to improve the accuracy of the peak value [mu] m, may be used either peak values, at (20) μm
Various values can be used as the peak value μm, such as ▲ μ ⁺ _m ▼ instead of, and − ▲ μ ⁻ _m ▼ instead of μm in the equation (21). From the above consideration, it is desirable that the value for correction is proportional to μ _o (value of magnetic susceptibility μ when magnetic field H = 0). However, in reality, this area is S / N of data. The peak value μm is used because the ratio is poor and it is difficult to determine the correct value. Of course, as described later, if μ _o can be accurately obtained by a means such as a moving average method, it is possible to determine the correction amount by using μ _o instead of μm.

If the correction coefficient α obtained as described above is stored in the ROM 69 and the correction coefficient α is read for each measurement of a normal sample and the measurement data is corrected, an accurate magnetization characteristic value that compensates for leakage flux can be obtained. You can

When the measurement data of the normal sample is corrected by using the fixed correction coefficient α in this way, some error will occur depending on the material of the normal sample and the like. Further, in order to reduce the error, for example, as shown in FIG. 12, the correction coefficient α is corrected by α = γQ−δ (22) according to the sharpness Q of the peak of the measurement data. As a result, the variations among the materials shown in Table 1 are corrected. Where γ and δ are experimentally obtained correction constants, the peak position is H _m , and the half width is H (1 /
2), the sharpness Q is Q = H (1/2) / H _m .
Further, as shown in FIG. 13, the correction coefficient α may be changed to α ₁ · μ _m , α ₂ · μ _m (α ₁ and α ₂ are constants) with the peak position H _m as a boundary. . Further, if the correction coefficient when H = 0 is α _o , β is the slope coefficient, α = α _o + β · H (23) As shown in FIG. 14, even if the correction coefficient α has a slope, good. In either case, the correction accuracy is improved. On the other hand, as shown in FIG. 15, H =
The correction amount may be obtained by multiplying the value μ _o when 0 by a constant multiple α · μ _o .

When μ ≧ 0, μ ′ = μ−α · μ _o (where μ ′ <0, μ ′ = 0) When μ <0, μ ′ = μ + α · μ _o (where μ ′> 0 However, μ '= 0. However, μ _o = (▲ μ ⁺ _o ▼-▲ μ ^- _o ▼) / 2 ▲ μ ⁺ _o ▼; value of μ when H = 0 on μ> 0 side ▲ μ ^- _o ▼; μ value of mu when the <0 side of the H = 0 Further, in place of the mu _o, when the μ _o ≧ 0 ▲ μ
⁺ _O ▼ used, μ <0 is to come later ^- ▲ μ - _o ▼ may be used. However, in this case, μ _o , ▲ μ ⁺ _o ▼,
▲ mu ^- _o ▼ To determine the "waveform data processing for scientific measurement" averaging means (Shigeo Minami ed such translation method P.86
~ P90 April 1986 QC publication) is preferable.

Although FIGS. 12 to 15 show only the positive side of μ, the same applies to the negative side.

The measurement data conversion unit 21 is provided with a parallel input / output interface 17 for exchanging data with the measurement data analysis unit 60, and the control signal SD1 from the parallel input / output interface 17 is sent to the triangular wave generation circuit 18. The triangular wave signal SD2 is generated and input to the magnetic measurement unit 20 via the amplifier 19. Further, a sample hold circuit 14 is provided, and the sample hold circuit 14 has a voltage V _D1 (when there is a magnetic thin film) or a voltage V _D (when there is no magnetic thin film) amplified by the amplifier 13 from the magnetic measurement unit 20. Has been entered. The sample hold circuit 14 is a triangular wave generation circuit 18
The timing signal SH from, the voltage V _D1 or voltage V
_D is sampled and the sampling data SD3 is input to the A / D converter 15. The A / D converter 15 converts the sampling data SD3 into a digital signal DS1 according to the timing signal STC from the triangular wave generating circuit 18, and transmits it to the measurement data analyzing section 60 via the parallel input / output interface 17.

Here, a method of generating the triangular wave signal SD2 in the measurement data converter 21 will be described. FIG. 16 is a diagram showing the details of the triangular wave generation circuit 18 and the amplifier 19, and in the triangular wave generation circuit 18, a clock oscillator 120 for generating a clock signal PS1,
Clock signal PS1 based on the setting value N of the magnetizing force setting signal GS1
N-ary counter 99 that counts and outputs pulse signal PS2
, A counter 98 that counts the pulse signal PS2 and outputs a count value PS3, and a ROM 96 (in which the voltage values (amplitude values) PS4 and PS5 for forming a triangular waveform based on the count value PS3 are stored in advance. Upper bits) and ROM97 (lower bits) are provided. Also, the output voltage value PS4,
D / A converter 95 that converts PS5 to triangular wave PS6 of analog signal, converter 94 that changes the polarity of triangular wave PS6 to generate triangular wave PS7, and switches triangular waves PS6 and PS7 based on timing signal PS7 from counter 98 And a switch circuit 121 that outputs a triangular wave signal SD2. Further, the one-shot circuits 122 to 125 for converting the waveform of the timing signal PS8 from the counter 98 to generate the timing signals STC and SH.
Is provided.

On the other hand, in the amplifier 19, an amplitude control circuit 93 composed of resistors R to 8R for varying the amplitude of the triangular wave signal SD2 by the magnetizing force setting signal GS2 and outputting the triangular wave signal SD3, and amplifying the triangular wave signal SD3 to measure magnetism. Amplifiers 91, 92 are provided for the section 20. Although the magnitude of the magnetizing force is proportional to the period of the generated triangular wave, if the period of the triangular wave is 1.024 [S] at 10000 [Oe], the magnetizing force is 1000 [O].
When set to [e], the triangular wave cycle is 0.1024 [S]
I am trying to become. This is to keep dΦ / dt constant.

In such a configuration, the triangular wave generation circuit 18 is
As shown in FIG. 17 (A), the waveform of one cycle of the triangular wave TR generated within the time T is set as the sampling number 8192, and the voltage values PS4 and PS5 (PS4 and PS5 are combined to 1 in advance for each sampling value). The two voltage values are stored in ROM96,97. Here, the pulse t ₁ is t ₁ = T / 8192, and the width of t ₁ is equal to the period of the pulse signal PS2. The voltage value is read from the ROMs 96 and 97 corresponding to the count value of the pulse signal PS2, a stepwise waveform is generated as shown in the figure, and the D / A converter 95 and the converter 94 are generated.
Is converted into an analog triangular wave signal SD2 and output via the amplifier 19. In addition, FIG. 17 (B) shows the above pulse width.
The relationship between t1 and the timing signals SH, STC is shown. For example, one timing signal SH and one timing signal SH8 are obtained by the pulse signal PS8 obtained every time the counter 98 counts eight pulse signals PS2.
Each timing signal STC is obtained. A time difference t3 is generated between the timing signal SH and the timing signal STC. That is, as shown in FIG. 17 (C), the timing signals SH and STC are obtained every t8, and the magnetic measuring unit 20
The voltage V _D1 or the voltage V _{D from} is digitally converted. The amplifier 19 is feedback-controlled so as to have a constant current, and the amplitude of the output triangular wave current I can be known from the set resistance value of the gain amplitude control circuit 93 of the amplifier 19. The number of samples taken by the A / D converter 15 is fixed at (8192/8) = 1024, for example, and in the CPU, from the amplitude of the excitation triangular wave and the order of the data converted and taken in by the A / D converter 15, Value of excitation current I and voltage V _D1 ,
Corresponding to V _D.

The measurement data analysis unit 60 includes a control unit for each unit and a memory unit 61
A CPU 73 that reads data from the RAMs 62 and 63 and performs calculations,
A ROM 62 that stores a control program and the like, and a RAM 62 that stores differential output voltage data of the magnetic head 1 when the magnetic thin film 200 is on the magnetic head 1.
And a RAM 63 for storing differential output voltage data of the magnetic head 1 when the magnetic thin film 200 is not provided, and a memory unit 61 for storing other various input data. Furthermore,
Clock for displaying date and time on display 68
64 is provided, and the GP-IB interface 22 and the parallel input / output interfaces 24 and 70 are provided as interfaces. The GP-IB interface 22 is connected to the GP-IB output connector 23, and the parallel input / output is provided. The interface 24 has a marker movement motor for moving the marker 83.
26, a holding arm moving motor 27 for moving the holding arm 81, and a magnetic head moving motor 25 as magnetic head moving means for moving the magnetic head 1 are connected. Further, the parallel input / output interface 70 is connected with a buzzer 72 for notifying by sound whether the magnetization characteristic is good or bad, and a printer output connector 71 for outputting the magnetization characteristic value by the printer. Further, a display controller 67 for driving the display 68 and a key controller 28 for controlling input data from the keyboard 29 are provided as controllers, and the display controller 67 has a video RAM 65 for storing images of two screens. , 66 are connected.

The operation of the measuring apparatus 80 having such a configuration will be described with reference to the flowchart of FIG.

First, the power switch 84 of the measuring device 80 is turned on, and the numeric keypad of the keyboard 29 is used to pass the magnetization characteristic value of the magnetic thin film 200 and the magnetizing force range setting value (1000 [Oe] to 10000 [O].
10 steps up to [e] are input (step S1), the data of the pass range is stored in the memory unit 61 of the measurement data analysis unit 60. The data of this pass range are the lower limit and the upper limit of saturation magnetic flux Φm (saturation magnetic flux density Bm), residual magnetic flux Φr (residual magnetic flux density Br), coercive force HC, squareness ratio D (= Φr / Φm = Br / Bm), etc. Enter the value as appropriate. Next, a mode is selected with the keyboard 29 (step S2). When the measurement mode is selected, a normal sample such as a magnetic card to be measured is inserted and placed on the table 82, and the magnetic thin film 200 is measured. The part is aligned with the marker 83 (step S3). Usually, the measurement data of the sample is digitized and stored in the memory unit 61, and the correction arithmetic expression of the expression (20) or the expression (21) is executed.
In this case, the characteristics of the band-shaped sample 200A are separately obtained in advance and the correction coefficient α is stored in the ROM 69, and the stored correction coefficient α is read out during the measurement of the normal sample to perform the correction calculation. The correction coefficient α may be corrected as shown in FIGS. 12 to 15. When the key operation is performed, the holding arm motor 27 is driven to lower the holding arm 81 in the N direction, and the sample such as the mounted magnetic card is pressed and fixed. After that, reconfirm that the measurement part of the magnetic thin film 200 is not misaligned and perform key operation.
26 is driven, the marker 83 is retracted in the direction M in FIG. 1 and is housed in the apparatus, and the magnetic head moving motor 25 is driven to set the magnetic head 1 on the magnetic thin film 200 such as a magnetic card. The measurement data analysis unit 60 transmits a control signal to the measurement data conversion unit 21 to start measurement of the magnetization characteristic (step S4). The triangular wave signal SD2 output from the triangular wave generation circuit 18 of the measurement data conversion unit 21 passes through the amplifier 19 and the primary coil 2 of the magnetic head 1 of the magnetic measurement unit 20,
3 is applied to the magnetic field H between the gaps 1A and 1B of the magnetic head 1.
Generate. A voltage proportional to the time change of the magnetic flux flowing in the magnetic core 1 is generated from the secondary coils 4 and 5, and the voltage signal V _D1 is generated via the amplifiers 10 and 11 and the differential amplifier 12 as described above.
Is obtained, and this V _D1 is input to the sample hold circuit 14 in the measurement data converter 21. Then, the sampled sampling data SD3 is converted into a digital signal DS1 by the A / D converter 15, and the parallel input / output interface 1
It is input to the measurement data analysis unit 60 via 7. Triangular wave 1
When all the voltage signals VD1 are stored in the RAM 62 for each cycle at time t8, the magnetic head moving motor 25 is driven, the magnetic head 1 is separated from the magnetic thin film 200, and the triangular wave 1 is similarly generated.
All the voltage signals VD are stored in the RAM 63 every time t8 for the period, and then the signals corresponding to the RAMs 62 and 63 are subtracted. The hysteresis curve and the magnetization characteristic values Φr, Φm, Hc, D calculated by the CPU 73 as described above are stored in the memory unit 61 as measured values (step S5). In this case, in the present invention, the measurement is repeated N times to obtain the parallelism. Therefore, even if there is noise in one sampling as shown in FIG. 19, the noise is obtained by obtaining the average value (broken line). To be removed. When the magnetic head 1 is on the magnetic thin film 200, the data for N cycles of the triangular wave is added and stored in the RAM 62. After that, the magnetic head 1 is separated from the magnetic thin film 200 and the data for N cycles of the triangular wave is added. Then, it may be stored in the RAM 63. Further, although the correction amount alpha · mu _m so that if it becomes larger than the original data mu a value mu '= 0 after the correction in the present invention, in the data mu As shown in FIG. 20 If noise is included, φ-H
The residual noise component left by the correction during integration during the calculation of the characteristics is integrated (RN in the figure), the value of the magnetic flux Φ becomes larger than it actually is, and the squareness ratio D = Φ _r / Φ _m becomes smaller. However, in the present invention, such inconvenience is solved because the data is averaged to remove the noise.

The CPU 73 compares the pass range set in advance with the above-mentioned measured value, and judges whether the result is acceptable or not with the letters “OK” and “NG”.
As shown in the figure, the hysteresis curve, the measured value and the like are displayed on the display 68 and stored in the video RAMs 65 and 66 as an image memory via the display controller 67. In addition, the buzzer 72 is driven via the parallel input / output interface 70.
And a continuous sound are generated (steps S6 and S7), and in the case of the above-mentioned "NG", an intermittent sound such as "beep ..." is generated (steps S6 and S8). All of these magnetization characteristic values are stored in the memory unit 61 (step S9). The memory area of the memory unit 61 is secured in the RAM for 100 data, and the data is sequentially logged in time series together with the measurement time data from the clock 64. The return of the marker 83 to the initial position is performed at the same time when the magnetic head 1 is separated from the magnetic thin film 200, and the upward movement of the holding arm 81 is performed after all the voltage signals V _D are sampled.

On the other hand, when the mode conversion is not designated by the key input, the next magnetic card or the like waits for measurement, and when the data processing mode I is selected by the key input (step S1
0, S2), the CPU 73 calculates the logging data of the memory unit 61, and displays the X-R control chart of the selected specific magnetization characteristic value (eg Φr) as shown in FIGS. 22 (A) and (B). Display 68.

Here, the procedure for creating an X-R control chart will be described. First, as prerequisites, N: total number of data, n: group size, k:
Set the number of groups. Then, N automatically counts the data in the memory, and n is a user input (n = 3, 4, 5). Further, k is a quotient obtained by k = N / n, and the remaining data is not used. For example, when N = 98 and n = 3, k =
Set to 32 and do not use the 97th and subsequent data. The average value for each group is And the total average of the averages for each group Is (= CL) And the upper and lower control limit lines UCL and LCL are Is. However, A ₂ and D ₄ are calculated according to the following Table 2.

When the above data is displayed in a graph, a graph as shown in FIG. 22 (A) is obtained. However, the horizontal axis shows the group number, and when n = 3, it is a scale of "5" in increments of "33".
When = 4 and n = 5, the scale is "5" each up to "25". Also, the vertical axis represents x, and the number of dots between LCL and UCL is fixed, and the numerical values represent LCL, CL, and UCL. Then, the variation R for each group is R _j = x _max −x _min (28), and the total average value of the variation R for each group is The upper and lower control limit line UCL is UCL = D ₄ ……… (30). However, D ₄ is obtained from Table 2 above. When the above data is displayed in a graph, a graph as shown in FIG. 22 (B) is obtained. However, the number of dots is fixed between 0 and UCL (the line of CL is automatically calculated and displayed), the numerical values are displayed as CL and UCL, and the solid line and the broken line are used properly as shown in the figure.

When the data processing mode II is selected by the key input (step S2), the CPU 73 calculates the logging data of the memory unit 61 (step S13) and displays the histogram of the selected specific magnetization characteristic value (for example, Φr). display
It is displayed on 68 (step S14). In this case, first, as a precondition, the maximum number of classes on the horizontal axis is set to "10", and the range on the vertical axis is automatically set to three types of 80, 40, and 20. Furthermore, the scale on the horizontal axis displays the values of x _max and x _min . And the number of classes k As the step size H _M , the average value, and the standard deviation σ Ask in. By substituting the data into the above equations (31) to (34) and displaying them in a graph, the graph shown in FIG. 23 is obtained.
However, the number of data N automatically counts the data stored in the memory unit 61, and the maximum number of data is "100".

In addition, the measurement data analysis unit 60, display check,
Buzzer check, motor check, ROM / RAM check,
Since it has a self-diagnosis function such as printer check, maintenance can be performed by key input.

(Modification) The winding of the magnetic core, the primary coil, and the secondary coil of the magnetic head used in the present invention is not limited to that shown in FIG. 2, and the magnetic core 1 shown in FIG. Alternatively, the structure may be bent at the center of the horizontal axis, and the primary coil 30 may be wound around the connecting arm 1C of the magnetic core 1 as shown in FIG. Further, as shown in FIG. 25, the primary coils 31 to 34 may be wound in series on each arm of the magnetic core 1, and, for example, the secondary coils may be wound so as to overlap the primary coils 31 and 34. 26th
As shown in the figure, the magnetic cores 40 and 41 are separated and magnetically shielded by the shield material 42, and the primary coil 43 and the secondary coil 44 are wound around the magnetic core 40, and the primary coil 45 and the secondary coil are wound around the magnetic core 41. The coil 46 may be wound. The magnetic cores 50 and 51 may be completely separated as shown in FIG. 27, and a primary coil and a secondary coil may be wound around the magnetic cores 50 and 51, respectively. Further, as shown in FIG. 28, a plate-shaped magnetic core 60
The primary coil 61 is wound around the magnetic core 60 and the secondary magnetic cores 62 and 63 connected to both ends of the magnetic core 60 are respectively provided with two coils.
Next coils 64 and 65 may be wound. Furthermore, although the constant frequency triangular wave is applied to the primary coil in the above description, a sine wave or the like may be used. Further, the differential output voltage V _D1 may be integrated by the CR integrating circuit without adopting the software integration method. In this case, when the differential output voltage V _D without the magnetic thin film 200 cannot be ignored, the integrated value of the differential output voltage V _{D1 with} the magnetic thin film 200 and the differential output voltage without Take the integrated value of V _D into the computer, synchronize with the applied magnetic field,
It is also possible to improve accuracy by taking the difference.

As described above, according to the magnetization characteristic measuring device of the present invention,
By simply setting the magnetic thin film portion such as magnetic printing, magnetic tape, magnetic disk, magnetic card, etc. in the device, it is possible to accurately measure the magnetic characteristic of the magnetic thin film by correcting the leakage flux, and to determine whether the magnetic characteristic is acceptable or not. Since the determination is displayed on a display screen or a buzzer sound, there is an advantage that the inspection process is labor-saving. Further, since the quality is displayed according to a preset standard, there is an advantage that it is easy to standardize the quality standard. Further, since it has a built-in clock function, it is possible to hold, calculate, analyze, and print out the measurement data corresponding to the time data, and there is an advantage that data processing is easy. Further, it is easy to carry because it is not large like the conventional device and is integrated, and operability is good because guidance is given from the display screen. Further, since it has a self-diagnosis function, it has an advantage of being excellent in maintainability.

[Brief description of drawings]

FIG. 1 is a diagram showing an external configuration of a magnetization characteristic measuring apparatus according to an embodiment of the present invention, and FIG. 2 is a circuit block configuration diagram thereof.
FIG. 3 is a diagram showing a state of magnetic flux in a gap portion of a magnetic head, FIGS. 4 and 5 are characteristic diagrams of magnetic fields, FIG. 6 is a diagram for explaining magnetic flux with respect to a band-shaped sample, and FIGS. 9
The figure is a diagram for explaining the magnetic field change of the normal sample, FIGS. 10 and 11 are diagrams for explaining the characteristic difference and the offset between the normal sample and the band-shaped sample, and FIGS. 12 to 15 are the correction factors, respectively. FIG. 16 is a detailed diagram of a triangular wave generating circuit, FIGS. 17 (A) to (C) are diagrams for explaining a method of generating a triangular wave, and FIG. 18 is an operation flowchart of the magnetization characteristic measuring device. 19 and 20 are diagrams for explaining the effect of noise removal according to the present invention, FIGS. 21 to 23 are diagrams showing the states of graphs displayed on the display, and FIGS. 24 to 28 are FIG. 29 is a diagram showing another example of the structure of the magnetic head, FIG. 29 is a diagram for explaining a general method for detecting the magnetization characteristic, and FIG. 30 is a diagram showing a state of the magnetic tape. 1 ... Magnetic head, 2,3 ... primary coil, 4,5 ... secondary coil, 10,11,13,19 ... amplifier, 12 ... differential amplifier, 14
...... Sample and hold circuit, 15 …… A / D converter, 17
...... Parallel input / output interface, 18 …… Triangular wave generation circuit, 20 …… Magnetic measurement unit, 21 …… Measured data conversion unit, 29
...... Keyboard, 60 …… Measurement data analysis unit, 68 …… Display, 80 …… Magnetic characteristic measuring device, 81 …… Presser arm, 82 …… Table, 83 …… Marker, 84 …… Power switch.

Claims (8)

[Claims] 1. A differential magnetic head, a triangular wave signal generating means for exciting the differential magnetic head with a triangular wave signal, and a differential output voltage of the differential magnetic head is sampled and converted into a digital value. Measurement data conversion means, storage means for storing a correction coefficient α for correcting the influence of leakage magnetic flux from the head side surface outside the gap of the differential magnetic head, and the digital value for the magnetic thin film to be measured. And a measurement data analysis means for correcting and calculating the magnetization characteristic value of the magnetic thin film to be measured based on the correction coefficient α stored in the storage means. Characteristic measuring device. 2. The magnetization characteristic value of the magnetic thin film to be measured is
When the peak value of the magnetic field H vs. magnetic susceptibility μ characteristic is μm, μ
When ≧ 0 μ ′ = μ−α · μm, When μ <0 μ ′ =
2. The magnetic thin film magnetization characteristic measuring device according to claim 1, wherein the correction is performed with .mu. +. alpha..mu.m, and the correction result is integrated to obtain a magnetic field H vs. magnetic flux Φ characteristic or a magnetic field H vs. magnetic flux density B characteristic. 3. The magnetization characteristic value of the magnetic thin film to be measured is
The positive / negative peak value of the magnetic field H vs. magnetic susceptibility μ characteristic is ▲ μ ⁺ _m ▼, ▲
When μ ⁻ _m ▼, μm = (▲ μ ⁺ _m ▼ − ▲ μ
⁻ _M ▼) / 2, when μ ≧ 0, μ ′ = μ−α · μ
When m and μ <0, the correction is made by μ ′ = μ + α · μm, and the correction result is integrated to obtain the magnetic field H vs. magnetic flux Φ characteristic or the magnetic field H vs. magnetic flux density B characteristic. A magnetic thin film magnetization characteristic measuring device as described above. 4. The magnetization characteristic value of the magnetic thin film to be measured is
The positive / negative peak value of the magnetic field H vs. magnetic susceptibility μ characteristic is ▲ μ ⁺ _m ▼, ▲
μ ^- _m ▼, and if μ ≥ 0, then μ '= μ-α ・ ▲
When μ ⁺ _m ▼, μ <0, the correction is made by μ ′ = μ−α · ▲ μ ⁻ _m ▼, and the correction result is integrated to obtain the magnetic field H vs. magnetic flux Φ characteristic or the magnetic field H vs. magnetic flux density B characteristic. The magnetic thin film magnetization characteristic measuring device according to claim 1, wherein: 5. The magnetization characteristic value of the magnetic thin film to be measured is
The value when the positive / negative H = 0 of the magnetic field H vs. magnetic susceptibility μ characteristic is ▲ μ ⁺
_{When o} ▼ and ▲ μ ⁻ _o ▼, μ _o = (▲ μ ⁺ _o ▼ − ▲
μ ⁻ _o ▼) / 2 and μ ≧ 0, μ ′ = μ−α · μ
When o and μ <0, the correction is made by μ ′ = μ + α · μo, and the correction result is integrated to obtain the magnetic field H vs. magnetic flux Φ characteristic or the magnetic field H vs. magnetic flux density B characteristic. A magnetic thin film magnetization characteristic measuring device as described above. 6. The magnetization characteristic value of the magnetic thin film to be measured is
The value when the positive / negative H = 0 of the magnetic field H vs. magnetic susceptibility μ characteristic is ▲ μ ⁺
_o ▼, ▲ μ ⁻ _o ▼, and if μ ≧ 0, μ ′ = μ
-Α ・ ▲ μ ⁺ _o ▼, when μ <0 μ '= μ-α ・ ▲ μ
^- _o ▼ be corrected by this correction result by integrating a magnetic field H versus flux Φ characteristics or magnetization characteristics measuring device of the magnetic thin film according to claim 1 which is to obtain the magnetic field H versus flux density B characteristic. 7. The correction coefficient α is corrected to α = γQ−δ, where γ and δ are the coefficients with respect to the sharpness Q of the magnetic field H versus magnetic susceptibility μ characteristic of the magnetic thin film to be measured. The magnetic thin film magnetization characteristic measuring device according to claim 1, wherein 8. The correction coefficient α, with the peak position of the magnetic field H vs. magnetic susceptibility μ characteristic of the magnetic thin film to be measured as a boundary, with α ₁ and α ₂ as constants α ₁ .μm, α ₂ .multidot. The magnetic thin film magnetization characteristic measuring device according to claim 7, wherein the magnetic thin film has a thickness of μm.