JP3052685B2 - Tape speed fluctuation measurement method and recording track inspection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring a tape speed fluctuation of a magnetic tape on which a signal is recorded by a magnetic recording / reproducing apparatus and a method for inspecting a recording track.

[0002]

2. Description of the Related Art In recent years, the size of audiovisual equipment, such as portable audio tape reproducing apparatuses and movies, has been reduced. On the other hand, especially movies and stationary V
Long-term recording is required for video recording media such as TRs. An important technique for satisfying such demands is high-density recording of video and audio signals. Magnetic recording / reproducing devices such as VTRs and DATs have also been used to achieve narrower tracks, thinner tapes, and shorter recording wavelengths in order to achieve high-density recording.

[0003] In order to realize such high-density recording while maintaining compatibility between recording / reproducing equipment for each standard such as VHS system VTR and DAT, recording of a track with high linearity is performed. Is important. For that purpose, a high-precision head scanning mechanism and a magnetic tape drive mechanism are required. In order to develop such a mechanism, it is important to understand what kind of recording position error can occur when performing high-density recording.
That is, a method of inspecting the linearity of the recording track is important. The following is an example of a conventional recording track inspection method.

FIG. 7 is a diagram showing a traversing method which is the most basic method of the recording track inspection method. In FIG. 7, 1 is a magnetic tape, and 2 is a pattern of a recording track visualized by developing using a magnetic powder. L3 is a measurement line for reading the track position in the width direction of the tape. The position of recording track 2 is determined by measuring line L
The data is read by a microscope (not shown) along the line 2, one virtual track 13 is reproduced from the obtained data, and the linearity of the recording track is measured.

There are the following three problems with the crossing method. The first point is that the transverse method only measures the position of the recording track 2 in the width direction of the magnetic tape 1, and the measured value includes a change in the recording track interval caused by a tape speed fluctuation. Therefore, it is not possible to measure only the linearity of the recording track, which depends on the accuracy of the vertical axis of the cylinder or the lead for regulating the magnetic tape. 2
First, in the crossing method, the linearity of one virtual track is measured using several tracks. Therefore, the measurement result is time-averaged, and it is not possible to measure a temporal variation in track linearity. Third, when measurement is performed at each measurement point using a microscope or the like, it is extremely troublesome and there is a possibility that a measurement error by a measurer may occur.

Therefore, as a conventional method for solving the first problem, the evaluation of the recording track linearity mainly by eliminating the influence of the tape speed deviation (fluctuation of the average tape speed) has been performed. For example, in JP-A-57-122307 and JP-A-57-122308, measurement errors due to fluctuations in tape speed and expansion and contraction of a magnetic tape are suppressed by using two or more measurement lines, and the track tilt angle is reduced. And a method for measuring linearity.

Japanese Patent Application Laid-Open No. 59-14102 discloses that a track position is measured along a measurement line in a width direction of a magnetic tape by a transverse method, a CTL pulse position is read, and a tape average speed at each measurement point is measured. By asking
A method is described for performing track linearity measurement that eliminates the effects of tape speed variations.

The one described in JP-A-62-172505 is as follows. First, the track position is measured in the width direction of the magnetic tape. One virtual track is considered from the obtained data, and a regression line for the virtual track is obtained. The tape speed deviation is obtained by obtaining the inclination, and the correction when measuring the linearity of the track is performed based on the tape speed deviation.

As a method for dealing with the second and third problems, Japanese Patent Laid-Open No. 3-222102 discloses a method in which a recording track is regarded as a lattice and the track is bent instead of a crossing method using a microscope or the like as described above. A method of measuring track linearity by adopting a technique of stripe / grid image analysis by considering such as a deformation of a grid is described. In this method, two-dimensional data can be captured using an imaging device such as a CCD camera. For data analysis, a computing device such as a workstation can be used. Therefore, it is possible to detect a temporal change in the linearity of the track with high accuracy in a relatively short time without a measurement error by a measurer.

[0010]

However, according to the above-described method for inspecting the recording pattern of a magnetic tape, Japanese Patent Application Laid-Open No. 57-122307 and Japanese Patent Application Laid-Open No.
In the case of Japanese Patent Application Publication No. 08-08, the influence of tape speed fluctuation and the like is canceled by taking the difference between two measurement points, so that it is not possible to measure the temporal fluctuation of track linearity. The problem of trouble and measurement error still remains.

Japanese Patent Application Laid-Open No. 59-14102 discloses that
Since the tape speed is obtained using the CTL signal recorded along the longitudinal direction of the magnetic tape as in the VHS system or the β system of the VTR, the magnetic tape recorded in a format having no CTL signal such as DAT Not applicable to

Japanese Patent Application Laid-Open No. Sho 62-172505 discloses that a tape speed deviation is obtained by calculating an average inclination angle of a track by fitting a regression line to the track. Because of the influence, there is a possibility that an accurate tape speed deviation value cannot be obtained.

In Japanese Patent Application Laid-Open No. 3-222102,
No consideration is given to eliminating the effect of recording track width variation due to tape speed variation when measuring recording track linearity.

The present invention has been made in view of the above-described problems, and it is possible to measure a tape speed variation with time even when there is no CTL signal or when there is a steady bending of a track. By correcting the measurement result of the track displacement distribution in the width direction of the magnetic tape by the tape speed fluctuation obtained by the above, a recording track inspection method of the magnetic tape which can evaluate the track linearity excluding the influence of the tape speed fluctuation. The purpose is to provide.

[0015]

According to the present invention, there is provided a tape speed fluctuation measuring method for solving the above-mentioned problems, which comprises: a method for visualizing and inspecting tracks on a magnetic tape recorded by a magnetic recording / reproducing apparatus; The longitudinal track displacement distribution of the track is measured along at least one measurement line in the longitudinal direction of the tape, and a regression curve is calculated based on the longitudinal track displacement distribution. It is characterized in that a speed fluctuation amount is obtained.

Further, the recording track inspection method of the present invention comprises:
In a method of visualizing and inspecting a track on a magnetic tape recorded by a magnetic recording / reproducing apparatus, a width-direction track displacement distribution of the track is measured along at least one measurement line in a width direction of the magnetic tape, and the magnetic field is measured. Along the at least one measurement line in the longitudinal direction of the tape, the longitudinal track displacement distribution of the track is measured in a range longer than the longitudinal component of the magnetic tape of the recording track. Or calculating a tape speed variation from a regression curve obtained by applying a polynomial approximation to the longitudinal track displacement distribution, and correcting the width direction track displacement distribution using the obtained tape speed variation. It is a feature.

According to another aspect of the present invention, there is provided a method for inspecting a track on a magnetic tape recorded by a magnetic recording / reproducing apparatus by visualizing the recorded track formed on the magnetic tape as an image. The captured image is held by a data holding unit, and the image held by the data holding unit is subjected to a Fourier transform in each of a longitudinal direction and a width direction of the magnetic tape. The frequency component is extracted, and the Fourier transform is performed on the frequency component to detect the recording track position. By comparing the recording track position with the reference track position, the longitudinal track displacement distribution and the width track displacement distribution of the magnetic tape are calculated. And calculating the tape speed fluctuation amount from the longitudinal track displacement distribution. It is characterized in that to correct the width direction track displacement distribution were using tape speed variation.

[0018]

According to the tape speed fluctuation measuring method of the present invention, the position of a recording track is measured along a measuring line in the longitudinal direction of a magnetic tape, a displacement distribution with respect to an ideal track is obtained, and a regression curve thereof is obtained. By calculating the tape speed fluctuation from the slope of this regression curve and the normal tape speed,
Even if there is no CTL signal and the track has a steady bend, it is possible to measure the tape speed variation over time.

Also, the recording track inspection method of the present invention
According to the above-described method, even when there is no CTL signal or when there is a steady bending of the track, it is possible to measure the amount of fluctuation in the tape speed with the passage of time. By correcting the measurement result of the displacement distribution, it is possible to evaluate the track linearity excluding the influence of the tape speed fluctuation.

In another recording track inspection method according to the present invention, by using image processing by the above-described method, the displacement distribution of a recording track with respect to an ideal track can be measured over the entire image of the obtained recording track pattern by using a magnetic tape. Measure with high accuracy in the width direction and longitudinal direction.
By performing a differential operation on the track displacement distribution in the longitudinal direction of the magnetic tape, the tape speed ratio can be determined over the entire image. By using this to correct the track displacement distribution in the width direction of the magnetic tape, the tracing method is not used, the CTL signal is not required, and even if the track has a steady curve, the entire captured image can be obtained. ,
It is possible to obtain a tape speed variation with time and a track displacement distribution in the width direction of the magnetic tape with time, which is not affected by a measurement error by a measurer, with high accuracy, in a short time and easily. Further, by correcting the track displacement distribution in the width direction using the obtained tape speed fluctuation amount, it becomes possible to evaluate the track linearity according to the passage of time excluding the influence of the tape speed fluctuation.

[0021]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a principle diagram for explaining a tape speed fluctuation measuring method and a recording track inspection method according to the present invention. An example of a recording track pattern is indicated by a solid line, and an ideal track pattern serving as a reference according to a format is indicated by a broken line. In FIG. 1, 1 is a magnetic tape, 2 is a recording track (solid line) visualized by a development process, and 3 is an ideal track (broken line). L1 and L2 are measurement lines in the magnetic tape longitudinal direction and the magnetic tape width direction, respectively. The tape running direction is the X direction.

FIG. 2 is a schematic configuration diagram of a measuring device used in the present embodiment. Reference numeral 4 denotes a microscope for enlarging and observing the magnetic tape 1. Reference numeral 5 denotes an XY stage provided as an observation table in the microscope 4 for mounting the magnetic tape 1 and moving the magnetic tape 1 in the X and Y directions. Reference numeral 6 denotes a movement distance counter that counts and displays the amount of movement of the XY stage 5 in each of the X and Y directions. An arithmetic unit 7 calculates a regression curve and a tape speed variation from the measurement data obtained by the moving distance counter 6.

FIG. 3 shows an example of the track displacement distribution 8 (indicated by +) in the longitudinal direction of the magnetic tape and the regression curve 9 obtained from the track displacement distribution 8 in the longitudinal direction of the magnetic tape obtained by the present embodiment.

Hereinafter, the method of measuring tape speed fluctuation according to the present invention will be described. First, in order to obtain the track displacement distribution in the longitudinal direction of the magnetic tape, a plurality of track displacement amounts in the longitudinal direction of the magnetic tape from the ideal track 3 of the recording track 2 are obtained. Specifically, the position of the intersection P _n (n = 0, 1, 2,...) Between the boundary line of the recording track 2 and the measurement line L1 along a certain measurement line L1 in the longitudinal direction of the magnetic tape is set to an arbitrary value. to measure the intersection P ₀ as the origin. At this time,
As a measuring method, a method using an apparatus having a configuration as shown in FIG. 2 can be considered. In this method, the measurer sets the visualized magnetic tape 1 serving as a sample so that the longitudinal direction thereof completely matches the X direction of the XY stage 5. The focus is adjusted so that the magnetic tape 1 can be clearly seen through the eyepiece of the microscope. Measurement origin P ₀
The XY stage 5 is moved so that the position coincides with a line provided in the field of view of the microscope, and the moving distance counter 6 is reset to 0 when the position coincides. Next, X
The Y table 5 is moved in the X direction, and the value of the movement distance counter 6 when the line in the field of view of the microscope coincides with the next intersection is read into the arithmetic unit 7. Then, the XY table 5 is set to X
The value of the movement distance counter 6 when the line in the microscope field of view coincides with the next intersection is read into the arithmetic unit 7. Hereinafter, by repeating this operation, P
The position distribution of _n (n = 0, 1, 2,...) is obtained.

Next, the following operation is performed inside the arithmetic unit 7. The intersection between the boundary line of the ideal track 3 and the measurement line L1 corresponding to P _n (n = 0, 1, 2,...) Is defined as P _0n (n = 0, 1, 2,...). P
The origin of _0n (n = 0, 1, 2,...) _Is P _00, and P ₀
, P _0n (n = 0, 1, 2,...)
The position distribution in ()) can be calculated from a format that defines an ideal track. Therefore, the track displacement distribution in the longitudinal direction of the magnetic tape is P _n −P, which is the difference between P _n and P _0n.
By calculating _0n (n = 0, 1, 2,...)
A distribution diagram as shown in FIG. 3 is obtained.

The regression curve 9 as shown in FIG. 3 is obtained by applying a polynomial approximation to the obtained track displacement distribution in the longitudinal direction of the magnetic tape. Slope α at each point of this regression curve 9
Indicates the ratio of the tape speed at each point to the normal tape speed, that is, the tape speed ratio. Here, α is a dimensionless quantity. Assuming that the normal tape speed is V _th , the tape speed fluctuation can be obtained by inputting the regression curve 9 to the differentiating circuit and multiplying the difference by V _th .

When measuring the tape speed fluctuation amount using the method of this embodiment, there is no problem even if the recording track has a bend as long as it is stationary. This is because, if the bending of the recording track is stationary and does not depend on time, the interval between the recording tracks in the longitudinal direction of the magnetic tape depends on the tape speed and is not affected by the bending of the recording track.

As described above, in this embodiment, even if there is no CTL signal and there is a steady curve of the track, it is possible to measure the tape speed variation with time. Also, by making it possible to observe the time fluctuation of the tape speed, it becomes possible to detect tape slip and jitter with respect to the capstan while the tape is running.
Feedback to the improvement of tape running accuracy becomes possible.

Hereinafter, a first embodiment of the recording track inspection method of the present invention will be described. In this embodiment, a track displacement distribution in the longitudinal direction of the magnetic tape is obtained in the same manner as in the above embodiment. The measurement range at this time is a length that at least one track completely enters. Next, the same operation as in the case of the magnetic tape longitudinal direction is performed in the magnetic tape width direction,
The track displacement distribution in the width direction of the magnetic tape is obtained. Specifically, as shown in FIG. 1, along a certain measurement line L2 in the magnetic tape width direction, an intersection P _Wn (n = 0, 1, 2,...) Between the boundary line of the recording track 2 and the measurement line L2. _Is determined by the method using the microscope 4 as shown in the first embodiment after the origin P _W0 is determined. Next, P _Wn (n =
0, 1, 2,...), The intersection P _W0n (n = 0, 1, 2, 2, 3) of the boundary line of the ideal track 3 and the measurement line L2.
_{..) Are} calculated using the point P _W00 that coincides with P _W0 as the origin. Using these, P _Wn −P _W0n (n = 0,
By calculating (1, 2,...), The track displacement distribution in the magnetic tape width direction is obtained.

Next, the track displacement distribution in the width direction of the magnetic tape obtained as described above is corrected. First, among the measurement points on the measurement lines L1 and L2 in the longitudinal and width directions of the magnetic tape shown in FIG. 1, the boundary between both ends of an arbitrary track in the measurement area and the intersection of L1 and L2 is set. Note the three measurement points. Here, as an example, FIG.
Intersection P between boundary lines at both ends of middle track T and L1 and L2
_Two measurement points, ₂ , P ₃ , P _W3 , and P _W4 are taken up. The tape speed when this track T is formed on the magnetic tape is approximately the track displacement distribution in the longitudinal direction of the magnetic tape, considering that the time required to record one track T is very small. It considered the average of the slope between the P ₂ and P _3. That is, α in FIG. Here, α indicates the ratio of the tape speed to the normal tape speed, and is a dimensionless amount. The tape speed is the original value of α
By increasing the distance, the distance between P ₂ and P ₃ becomes α times, and the distance between P _W3 and P _W4 also becomes α times. Therefore,
If the distance between P _W3 and P _{W4 is} multiplied by 1 / α, a track displacement distribution in the magnetic tape width direction in which the influence of the tape speed fluctuation is canceled can be obtained.

Here, the correction coefficient β_nThink of the coefficient
You. This correction coefficient β_nIs the measurement point P_Wn(N = 0,1,
2, ...) for P_Wn, P_{W (n-1)}Tape speed between
Is a constant value α _n-1When approximated by
And

Β _n = (P _Wn P _{W (n−1)} ) · (1-1 /
α _n-1 ) + β _n-1 (n = 1, 2,...) where β ₀ = 0 P _Wn P _{W (n-1)} : Distance between P _Wn and P _{W (n-1)} , (P _Wn −P _W0n ) −β _n , (n = 0, 1, 2 _,.
By calculating (..), an accurate track displacement distribution in the width direction of the magnetic tape from which the influence of the tape speed fluctuation is removed is obtained.

As described above, even when there is no CTL signal or when there is a steady bending of the track, the track displacement distribution in the width direction of the magnetic tape can be obtained by using the measurement result of the tape speed variation with time. By correcting the measurement result, it is possible to evaluate the track linearity excluding the influence of the tape speed fluctuation.

In this embodiment, the measurement points P _Wn , P
P _Wn , P of the track displacement distribution in the longitudinal direction of the magnetic tape as the tape speed between _{W (n-1)} (n = 1, 2,...)
The average of the slope between _{W (n-1)} was used, but the regression curve of the track displacement distribution in the longitudinal direction of the magnetic tape was determined, and its P _Wn , P
_The tape speed α may be the slope of the tangent at the center of _{W (n-1)} or P _Wn and P _{W (n-1)} .

Hereinafter, a description will be given of a second embodiment of the recording track inspection method according to the present invention. In this embodiment, the first embodiment of the above-described recording track inspection method of the present invention is implemented by using image processing in measuring the track position.

FIG. 4 is a schematic configuration diagram of a measuring apparatus used in this embodiment. Reference numeral 1 denotes a magnetic tape to be measured, and 4 denotes a microscope for forming an image of the magnetic tape 1 on an image pickup device (not shown) of the CCD camera 10. Reference numeral 5 denotes the magnetic tape 1 provided on the microscope 4 as an observation table.
This is an XY stage for moving in the X and Y directions. Reference numeral 10 denotes a CCD camera for capturing an image of the magnetic tape 1 formed by the microscope 4 as an image. 11
Reference numeral denotes an image memory for storing an image captured by the CCD camera 10. Reference numeral 12 denotes an image calculation device that reads an image from the image memory 11 and performs a calculation process to calculate a tape speed variation and track linearity.

FIG. 5 is an example of the waveform of the luminance distribution of one line in the X direction or the Y direction of the image captured by the CCD camera 10. FIG. 6 is a schematic diagram of a power spectrum which is a sum of squares of a real part and an imaginary part of a frequency spectrum obtained when Fourier transform is performed on the luminance distribution of FIG.

First, the visualized track on the magnetic tape is captured as an image using the CCD camera 10. At this time, the longitudinal direction of the tape and the lateral direction (X direction) of the image are made to match. The capture range in the vertical direction (Y direction) of the image is the range in which tracks are recorded. Further, if tracks recorded by magnetic heads having different azimuths from each other are alternately arranged on a magnetic tape, the brightness of an image obtained by irradiating one azimuth with parallel light vertically becomes X In both the direction and the Y direction, the waveform becomes a waveform in which a bright portion and a dark portion are repeated, which is similar to that shown in FIG. On the other hand, when the Fourier transform is performed, a frequency spectrum as shown in FIG. 6 is obtained. Only the primary frequency component (corresponding to the hatched portion in FIG. 6) representing the primary harmonic component of the original waveform is extracted from this frequency spectrum, and the original waveform is smoothed to the real part by subjecting it to inverse Fourier transform. In the imaginary part, a waveform which is shifted by a half wavelength of the real part waveform is obtained. Taking the inverse tangent of the ratio of the real part to the imaginary part, the phase value of the primary harmonic wave of the original waveform at each pixel is obtained. The point on the ideal track 3 having the same phase value as the phase value at each pixel point of the recording track 2 obtained in this way, that is, the position of the point on the ideal track 3 corresponding to each pixel point of the recording track 2 is It is possible to calculate the actual distance per unit phase by knowing what μm one pixel of the captured image actually corresponds to. Therefore, displacement is obtained for all pixels in the obtained image.

Of the track displacement distributions obtained by the above process, those viewed in the longitudinal direction of the magnetic tape represent the tape speed fluctuations. The tape speed ratio at each pixel point can be obtained by performing a differential operation such as a difference or a smoothing differentiation.

Using the thus obtained tape speed ratio for each pixel, the track displacement distribution in the magnetic tape width direction is corrected for each pixel. Here, similarly to the first embodiment, the distribution of the correction coefficient β _mn at all pixel points is considered. _Here , m of β _mn represents the number of the column in the tape longitudinal direction, and n represents the number of pixels corresponding to the pixel in the tape width direction. β _mn is obtained by the following equation.

Β _mn = LEN · (1-1 / α _mn ) + β _{m (n−1)} where β _m0 = 0 m = 0,1,2,... N = 1,2,3,. LEN represents the actual length per pixel, and α _mn represents the tape speed of the m-th pixel in the magnetic tape longitudinal direction and the n-th pixel in the magnetic tape width direction.

Therefore, β _mn (m, n = 0, 1, 2, _{...) Is obtained} from the track displacement distribution in the magnetic tape width direction for all the pixels.
..) is subtracted to obtain the track displacement distribution in the magnetic tape width direction excluding the influence of the tape speed fluctuation.

Thus, without using the traversal method,
Even if there is no need for a CTL signal and there is a steady curve in the track, the entire captured image can be processed with high accuracy, in a short time, easily and without the influence of measurement errors by the operator. A track displacement distribution in the width direction of the magnetic tape according to the tape speed fluctuation amount and the passage of time according to the time is obtained. Further, by correcting the track displacement distribution in the width direction based on the obtained tape speed fluctuation amount, it is possible to evaluate the track linearity with time, excluding the influence of the tape speed fluctuation.

Although the above three embodiments show examples in which the present invention is applied to a recording medium recorded by a helical scan type magnetic recording device, the present invention measures only a track recorded by a helical scan type. The target is not limited, and for example, it can be applied to a case where recording is performed while moving a head for recording on a magnetic tape in a direction perpendicular to the longitudinal direction of the magnetic tape, and the same effect can be obtained. it can.

[0046]

As described above, according to the tape speed fluctuation measuring method of the present invention, the track displacement distribution is measured in the longitudinal direction of the magnetic tape, and the regression curve thereof is calculated. Even if there is a steady bending of the tape speed, it is possible to measure the tape speed variation with time.

Also, the recording track inspection method of the present invention
By measuring the track displacement distribution in the width direction of the magnetic tape and correcting it using the tape speed fluctuation amount obtained by the tape speed fluctuation measuring method of the present invention, even if there is no CTL signal, it is possible to obtain a steady track. Even if there is a bend, it is possible to measure the tape speed fluctuation amount with the passage of time, and by using the measurement result to correct the measurement result of the track displacement distribution in the width direction of the magnetic tape, the influence of the tape speed fluctuation is eliminated. Track linearity can be evaluated.

In addition, by introducing an image processing method into the recording track inspection method of the present invention, the traversing method is not used, the CTL signal is not required, and even if the track has a steady curve, , Over the entire captured image, with high accuracy, in a short time, easily, without being affected by measurement errors by the operator, the tape speed fluctuation amount according to the passage of time and the width direction track of the magnetic tape according to the passage of time. A displacement distribution is obtained. Further, by correcting the track displacement distribution in the width direction using the obtained tape speed fluctuation amount, it becomes possible to evaluate the track linearity according to the passage of time excluding the influence of the tape speed fluctuation.

[Brief description of the drawings]

FIG. 1 is a principle diagram for explaining a tape speed fluctuation measuring method and a recording track inspection method of the present invention.

FIG. 2 is a schematic configuration diagram of a measuring device used in an embodiment of the present invention.

FIG. 3 is a diagram showing an example of a track displacement distribution measurement result in the longitudinal direction of a magnetic tape and a regression curve thereof according to the present invention.

FIG. 4 is a schematic configuration diagram of a measuring apparatus used in an embodiment of the recording track inspection method of the present invention.

FIG. 5 is a diagram showing an example of a luminance distribution of one line in an X direction or a Y direction of an image captured by a recording track in the embodiment of the recording track inspection method of the present invention.

FIG. 6 is a diagram illustrating an example of a power spectrum obtained by performing a Fourier transform on the luminance distribution illustrated in FIG. 5;

FIG. 7 is a schematic diagram showing a conventional method for measuring the linearity of a recording track;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Magnetic tape 2 Recording track 3 Ideal track 4 Microscope 5 XY stage 6 Moving distance counter 7 Arithmetic unit 8 Track displacement distribution 9 Regression curve 10 CCD camera 11 Image memory 12 Image arithmetic unit 13 Virtual track L1 Measurement line in the longitudinal direction of magnetic tape L2 Measurement lines P ₀ , P ₁ , P ₂ ,... In the magnetic tape width direction Intersection points P ₀₀ , P ₀₁ , P ₀₂ ,... Of the measurement lines in the magnetic tape longitudinal direction and the boundaries of the recording tracks Intersection points P _W0 , P _W1 , P _W2 ,... Between the measurement line in the direction and the boundary of the ideal track P _W00 , P _W01 , P _{W02 ,.} ... Intersection between the measurement line in the width direction of the magnetic tape and the boundary of the ideal track

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G11B 15/467

Claims (3)

(57) [Claims] 1. A method for visualizing and inspecting a track on a magnetic tape recorded by a magnetic recording / reproducing apparatus, wherein a track displacement distribution in a longitudinal direction of the track along at least one measurement line in a longitudinal direction of the magnetic tape. And measuring a regression curve based on the longitudinal track displacement distribution, and calculating a tape speed variation using the regression curve. 2. A method for visualizing and inspecting a track on a magnetic tape recorded by a magnetic recording / reproducing apparatus, wherein a track displacement distribution in a track width direction is provided along at least one measurement line in a width direction of the magnetic tape. And measuring the longitudinal track displacement distribution of the track along at least one measurement line in the longitudinal direction of the magnetic tape in a range longer than the longitudinal component of the magnetic tape on the recording track, The tape speed variation is obtained from a direction track displacement distribution or from a regression curve obtained by applying a polynomial approximation to the longitudinal track displacement distribution, and the width direction track displacement distribution is obtained by using the obtained tape speed variation. A recording track inspection method characterized by correcting the following. 3. A method for visualizing and inspecting a track on a magnetic tape recorded by a magnetic recording / reproducing apparatus, wherein a recording track formed on the magnetic tape is captured as an image, and the captured image is held by data holding means. The image held by the data holding means is subjected to a Fourier transform in each of the longitudinal direction and the width direction of the magnetic tape, and a primary frequency component is extracted from a frequency spectrum obtained by the Fourier transform. To calculate the longitudinal track displacement distribution and the width direction track displacement distribution of the magnetic tape by comparing the recording track position with the reference track position. The speed fluctuation amount is obtained, and the width direction toe is used by using the obtained tape speed fluctuation amount. Recording track inspection method characterized by correcting the click displacement distribution.