JP2003006826A - Servo signal-testing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a servo signal-testing device which can conduct quality evaluation, analysis, investigation of defects and so on concerning a servo signal more properly and in more detail since it can test a specific location of a servo signal in the direction of the width of a magnetic tape. SOLUTION: The above purpose is achieved by having a reproducing means which reproduces the servo signal, a detecting means which detects the location on the servo signal of the reproducing means in the direction of the width of the magnetic tape from the result of the reproduction of the servo signal by the reproducing means, an extracting means which extracts a low-frequency component from the location detected by the detecting means of the reproducing means and a moving means which moves the reproducing means in the direction of the width of the magnetic tape so that the low-frequency component may take a prescribed value in accordance with the low-frequency component extracted by the extracting means.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of inspection of servo signals recorded on a magnetic tape.
The present invention relates to a servo signal inspection apparatus capable of inspecting a desired position of a servo signal in the width direction of a magnetic tape. 2. Description of the Related Art In the field of information recording using magnetic tape, a magnetic head for recording / reproducing information (hereinafter referred to as a recording / reproducing head) is used for recording / reproducing appropriate information.
However, it is necessary to accurately track the recording track of the magnetic tape. On the other hand, in recent years, there has been a strong demand for an increase in the storage capacity of magnetic tape, and in response to this, the width of the recording track tends to become narrower, making it difficult to accurately track the recording track by the recording / playback head. It has become to. Therefore, a servo signal is recorded on a magnetic tape, and the magnetic tape device reproduces the servo signal by a servo signal reproducing means (hereinafter referred to as a servo head) when recording / reproducing information. Depending on the playback result,
The recording / reproducing head tracking accuracy is ensured by moving the recording / reproducing head in the width direction of the magnetic tape. As a matter of course, in order for the magnetic tape to have a predetermined quality, the servo signal needs to be recorded with high accuracy. However, due to various factors, such as movement of the magnetic tape in the width direction (conveyance blur) due to magnetic tape conveyance accuracy at the time of servo signal recording, and lack of a magnetic head for recording servo signals, the servo signal may become positional. May have a defect such as an error, chipping, missing, or distortion. If the servo signal has such a problem, a magnetic tape having a predetermined performance cannot be manufactured.
Therefore, in manufacturing a magnetic tape, in order to manage the quality of the servo signal, the servo signal is inspected (verified) after the servo signal is recorded. The inspection of the servo signal is as follows.
Usually, the servo signal recorded on the magnetic tape is reproduced by using a dedicated inspection device. For example, when the servo signal is magnetically recorded on the magnetic tape, the servo signal is reproduced by the magnetic head (inspection head) of the inspection apparatus, and the position on the servo signal tracked by the inspection head is determined from the reproduction result. (Position in the magnetic tape width direction)
The quality of the servo signal is evaluated based on this information. Here, in a magnetic tape having a high recording density, the servo signal is very important, so that the entire servo signal is required to be of high quality. For example,
If the magnetic head for recording the servo signal is defective, a large number of servo signals (all in a severe case) may have a defect such as distortion or chipping in a part of the signal such as near the end in the width direction. As mentioned above, in the magnetic tape device,
The position of the recording / playback head is controlled by reproducing the servo signal. However, in the magnetic tape device, since the magnetic tape transport blur occurs, the servo head cannot always track the predetermined position of the servo signal. In some cases, the vicinity of a part is tracked. At this time, if there are defects near the ends of a large number of servo signals, the servo signals are not reproduced properly, so the position of the recording / playback head cannot be controlled properly. The servo signal is lost. In addition, when a defect occurs in the magnetic tape coating process, a magnetic defect extending in the longitudinal direction may occur in a part of the width direction. If the position of the magnetic defect is the servo signal recording position, the servo signal is defective, and the same problem occurs. When such an inconvenience occurs, it is necessary to inspect and analyze a defective portion of the servo signal, that is, a specific position of the servo signal, to quickly isolate and investigate the cause. However, in the servo signal inspection apparatus, since the position of the inspection head is fixed, a desired specific position of the servo signal cannot be inspected. An object of the present invention is to solve the above-mentioned problems of the prior art, and in an inspection apparatus for inspecting a servo signal recorded on a magnetic tape, inspects a specific position of the servo signal in the width direction of the magnetic tape. Can and therefore
Provided is a servo signal inspection apparatus capable of performing quality evaluation and analysis of a servo signal, investigation of a defect cause, and the like more suitably and in detail. In order to achieve the above object, the present invention is a servo signal inspection apparatus for inspecting a servo signal recorded on a long magnetic tape, and reproducing the servo signal. Reproducing means, a detecting means for detecting the position of the reproducing means in the width direction of the magnetic tape on the servo signal from the reproduction result of the servo signal by the reproducing means, and a low frequency component from the position of the reproducing means detected by the detecting means And a moving means for moving the reproducing means in the width direction of the magnetic tape so that the low frequency component becomes a predetermined value according to the low frequency component extracted by the extracting means. A servo signal inspection apparatus is provided. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A servo signal inspection apparatus according to the present invention will be described below in detail with reference to preferred embodiments shown in the accompanying drawings. In the following description, the position is the position in the width direction of the tape T (the direction of the arrow b in the figure) unless otherwise specified. FIG. 1 is a conceptual diagram showing an example of a servo signal inspection apparatus according to the present invention. A servo signal inspection device 10 (hereinafter referred to as inspection device 10) shown in FIG.
A device for inspecting (verifying) a servo signal S recorded on the tape T (hereinafter referred to as a tape T), and basically a magnetic head 12 for reproducing the servo signal S (hereinafter referred to as an inspection head 12). The head unit 14 arranged, a position control unit 16 for controlling the position of the inspection head 12, and the tape T is conveyed in the longitudinal direction indicated by the arrow a in FIG. Conveying means (not shown)
And have. In the illustrated example, the tape T on which the servo signal S is recorded has a plurality of recording tracks (data tracks) extending in the longitudinal direction in the width direction, and each recording track is sandwiched in the width direction. A servo track Tr is formed by recording a predetermined pattern of servo signals S in the longitudinal direction. Therefore, for example, when the tape T has four recording tracks, five servo tracks Tr are formed. In the example shown in the figure, three servo signals S tilted at a predetermined angle and three servo signals S tilted at the same angle in the opposite direction to this signal are formed as one pattern, and the servo track is obtained by repeating this pattern. Tr
Is formed. As apparent from FIG. 1, in this tape T, the output timing of the reproduction signal, that is, the output timing of the reproduction signal, that is, the position of the servo signal S (servo track Tr) that the magnetic head reproducing the servo signal S tracks. The output pulse is different. The output pulse is uniquely determined according to the transport speed of the tape T and the tracking position in the servo signal S. Therefore, it is possible to detect which position of the servo signal S the magnetic head is tracking from this pulse signal. In the magnetic tape apparatus for recording / reproducing information on the tape T, the servo of the magnetic head (hereinafter referred to as recording / reproducing head) for recording / reproducing information (hereinafter referred to as recording / reproducing head) is used. For example, the center of the servo signal S is set as a reference position of a magnetic head for servo signal reproduction (hereinafter referred to as a servo head), and the servo head and the recording / reproducing head are configured so as to be integrated or linked, and the servo head is used as a reference. The recording / reproducing head properly tracks the recording track while tracking the position. Under such a configuration, when recording / reproducing information by the recording / reproducing head, a pulse signal obtained by reproducing the servo signal S by the servo head is used to detect which position the servo head is tracking. , Adjust the position so that the servo head always tracks the reference position,
That is, the servo head is caused to follow the reference position. Thereby, the recording / reproducing head can accurately track the recording track. The present invention is not limited to the inspection of the servo signal of the tape T of the system that performs servo (timing-based servo) using the pulse signal obtained by reproducing such a servo signal. It can be used for servo signal inspection of servo magnetic tape. For example, a servo tape that is magnetically recorded is reproduced by a servo head, the position of the servo head is detected using the output signal intensity, and the servo tape can be used for servo tape. As described above, the inspection head 12 is disposed in the head unit 14. In the illustrated example, the inspection head 12 is arranged corresponding to all the servo tracks Tr of the tape T. For example, when the tape T has five servo tracks Tr, the head unit 14 is provided with five inspection heads 12a, 12b. The present invention is not limited to this. The inspection head 12 may be the same as the servo head mounted on the magnetic tape device corresponding to the tape T as long as it is properly calibrated. In the inspection apparatus 10 of the illustrated example,
Although the reproduction signal of the servo signal from the inspection head 12 is output only to the position control unit 16, the reproduction signal from the inspection head 12 is also output to an inspection unit (not shown). The inspection unit analyzes the reproduction signal of the servo signal S sent from the inspection head 12 and compares, for example, the proper reproduction signal at the inspection position of the servo signal with the reproduction signal of the servo signal actually output. As a result, servo signal defects such as missing, missing, or distorted servo signals are detected and output as hard copies or display displays. In addition,
The inspection of the servo signal is not limited to this example, and various inspections performed in the servo signal inspection of the magnetic tape such as the reproduction output intensity can be used. As described above, although not shown, the inspection apparatus 10 has a conveying means for conveying the tape T in the longitudinal direction for inspection of the servo signal. There is no particular limitation on the conveying means, and a known conveying means using a capstan, a pinch roller, a guide member or the like may be used. Also,
Conveyance speed, device configuration, required inspection accuracy, and type of tape T (ie, corresponding magnetic tape device)
What is necessary is just to determine suitably according to etc. The reproduced signal of the servo signal S from the inspection head 12 is sent to the inspection unit and position control unit 16 described above. The position control unit 16 receives an arbitrarily set servo signal S.
In order to properly inspect a specific position of the inspection head 12
The head unit 14 (that is, the inspection head 12) is fed back according to the servo signal reproduction result.
Is adjusted in the width direction (arrow b direction).
In the illustrated example, the position control unit 16 includes an A / D (analog / digital) converter 18 and a digital signal processing unit 20.
(Hereinafter, referred to as a signal processing unit 20), a drive control unit 22, and a drive unit 24 that moves the head unit 14 are configured. Hereinafter, the operation of the inspection apparatus 10 will be described in detail for the position controller 16 and the servo signal inspection apparatus of the present invention. In the following description, one servo track and the corresponding inspection head 1
However, the present invention is not limited to this, and the servo signal S may be simultaneously inspected for a plurality of servo tracks Tr. The inspection apparatus 10 of the present invention is an apparatus capable of performing inspection while following a specific position of the servo signal S. In addition to this, like the normal servo signal inspection apparatus, The servo signal may be inspected by fixing the inspection head 12 (head unit 14) at a predetermined position and reproducing the servo signal. These include, for example, a follow-up inspection mode for inspecting following a specific position,
As in the normal inspection mode in which the inspection head 12 is fixed, the inspection head 12 may be set as a mode, and one of them may be selected so that the inspection can be performed. When the inspection apparatus 10 inspects a specific position of the servo signal S recorded on the tape T, first, using an input means (not shown) may be used. Enter the position. The input of the inspection position is sent to the driving unit 24 of the position control unit 16, and the driving unit 24 moves the position of the head unit 14 in the width direction according to the instructed inspection position and designates the inspection head 12. Placed at the inspection position. In the illustrated example, as an example, the vicinity of the end of the servo signal S in the upper part (right side in the transport direction of the tape T) in the figure is inspected. When the movement of the head unit 14 is completed, the servo signal S is reproduced by the inspection head 12 while the tape T is conveyed in the longitudinal direction (in the direction of arrow a in the figure) by the conveying means. A reproduction signal from the inspection head 12 is output to the A / D converter 18 of the position controller 16. The A / D converter 18 performs A / D conversion on the reproduction signal and sends it to the signal processing unit 20 as a digital signal. The signal processing unit 20 binarizes a digital signal obtained by reproducing the servo signal S using, for example, a threshold value to obtain a pulse signal, and the inspection head 12 tracks which position of the servo signal S from this pulse signal. Position signal (Position Signal or less,
POS). The tracking position may be detected by a known method, for example, following the tracking of the servo track Tr by the servo head of the magnetic tape device corresponding to the tape T. Next, the signal processing unit 20
Digital low-pass filter (Low PassFilter)
A low-frequency component is extracted by performing a processing operation, and a low-pass filtered position signal (hereinafter referred to as F-POS) is obtained. The F-POS is sent to the drive control unit 22. The drive control unit 22 stores, for example, an appropriate POS (hereinafter referred to as a reference value) in a table according to each position of the servo signal S. Drive control unit 22
F-POS obtained by servo signal reproduction is
To be the reference value of the indicated inspection position, ie
The drive unit 24 moves the head unit 14 in the width direction (arrow b direction) so that the difference between the reference value and the F-POS obtained by reproducing the servo signal becomes zero. As described above, the inspection apparatus 10 in the illustrated example is
If a specific position of the servo signal S can be inspected and the inspection head 12 can accurately track the designated position, the POS should always be a predetermined value corresponding to the inspection position. However, POS fluctuates due to various factors such as magnetic tape conveyance blur (vibration in the width direction), servo signal S recording position error, and tape T manufacturing error associated with conveyance, and the tape T conveyance speed and servo signal. Depending on the recording density of S, etc.
Includes high frequency components above Hz. Here, F-POS obtained by low-pass filter processing of POS is a low-frequency component of POS, that is, sudden POS fluctuation such as POS fluctuation due to an error of each servo signal S, etc. 3 shows a gentle movement of the tracking position of the inspection head 12 on the servo signal S. Therefore, when inspecting an arbitrary position of the servo signal S, the position on the servo signal is instructed by adjusting the position of the inspection head 12 in the width direction so that the F-POS becomes the reference value. The inspection position is followed by the inspection head 12,
A specific position of the servo signal S can be inspected. As a result, for example, as schematically shown in FIG. 1, when a defect such as distortion near the end portion occurs in a large number of continuous servo signals S, the defect position is inspected, and the servo signal Quality assessment, analysis of the cause of defects, and countermeasures can be quickly performed. Further, since the position adjustment of the inspection head 12 by the F-POS is gentle with a low frequency, the influence of the servo signal S on the inspection result can be ignored. In the present invention, the driving means 24 (the moving means of the inspection head 12 (head unit 14)) is not particularly limited. For example, various actuators can be used as long as sufficient response and moving amount can be ensured. Various known materials such as electromagnetic materials such as piezo elements and magnetostrictive materials can be used. The servo signal inspection apparatus of the present invention has been described in detail above. However, the present invention is not limited to the above-described embodiment, and various improvements and modifications can be made without departing from the spirit of the present invention. Of course it is good. As described above in detail, according to the servo signal inspection apparatus of the present invention, since a specific position of the servo signal can be inspected, continuous defects in the servo signal can be obtained. In the case where the error occurs, the quality evaluation and analysis of the servo signal, the investigation of the cause of the defect, etc. can be performed more suitably and in detail.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a conceptual diagram of an example of a servo signal inspection apparatus of the present invention. [Description of Symbols] 10 (Servo Signal) Inspection Device 12 Inspection Head 14 Head Unit 16 Position Control Unit 18 A / D Converter 20 Signal Processing Unit 22 Drive Control Unit 24 Drive Unit

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Claims (1)

What is claimed is: 1. A servo signal inspection apparatus for inspecting a servo signal recorded on a long magnetic tape, comprising: reproducing means for reproducing a servo signal; and reproduction of a servo signal by the reproducing means. From the results, detection means for detecting the position of the reproducing means in the magnetic tape width direction on the servo signal;
Extracting means for extracting a low frequency component from the position of the reproducing means detected by the detecting means, and in accordance with the low frequency component extracted by the extracting means, the reproducing means is magnetized so that the low frequency component becomes a predetermined value. A servo signal inspection apparatus comprising a moving means for moving in the width direction of the tape.