JPH08194924A - Method of measuring head attachment height - Google Patents

Abstract

PURPOSE: To obtain a head attachment height highly accurately and quantitative ly by a method wherein, when a tape is reproduced, the height of a recording track when an error rate exceeds a specified value is measured. CONSTITUTION: In a 1-inch open-reel type frame Hi-Vision digital VTR, if an ordinary magnetic tape 1 is reproduced, a voice reproducing head 5, for instance, whose track width is 190μm scans the inside of a voice track 2 whose width is 360μm to obtain a reproduced digital signal. The signal is amplified by a voice amplifier 6 and decoded and a voice error rate is displayed on an error rate meter 8. If the attachment position of the voice reproducing head is shifted and juts out of the voice track 2, the voice error rate displayed on the error rate meter 8 is degraded. By utilizing this phenomenon, a tape 1 in which the voice recording tracks 2a and 2b are recorded so as to be intentionally shifted from each other to form a step is prepared. An error rate when this tape 1 is reproduced is measured by the error rate meter 8 and the attachment height of a reproducing head 5 can be obtained from the height of the recording track 2a whose error rate is acceptable and the height of the recording track 2b whose error rate is unacceptable.

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 head mounting height in a magnetic recording / reproducing apparatus in which recording and reproduction are performed by separate heads.

[0002]

2. Description of the Related Art In a magnetic recording / reproducing apparatus, if the mounting height of a head is deviated, a recording track on a magnetic tape cannot be reproduced normally, resulting in poor compatibility.

Therefore, as a method for confirming that the mounting height of the head is within the standard value, in the case of a recording head, it can be confirmed by developing a tape pattern and measuring the recording track height. In the case of, the method of mechanically measuring the mounting height of the head with a device using a microscope and the playback output while holding the tape end by hand while playing the tape recorded with the same track width as the playback head track width There is a method of judging the quality of the mounting height of the reproducing head based on the level change amount.

[0004]

However, in the head mounting height measurement by a device using a microscope, it is not possible to measure while actually reproducing the tape. Therefore, the head mounted on the tape and the magnetic recording / reproducing device. I don't know the relative height with. Further, in the measurement of the mounting height of the head using a tape recorded with the same track width as the reproducing head, the mounting height of the head is standard because the reproduction output level is measured by pressing the tape end while reproducing the tape. It is not possible to quantitatively know how much it is more than the value. Furthermore, the problem of damaging the tape also occurs.

It is an object of the present invention to provide a head mounting height measuring method which can solve the above problems.

[0006]

A head mounting height measuring method according to the present invention comprises a tape on which recording tracks are staggered at several heights and recorded, and means for measuring an error rate. Has been done.

[0007]

The error rate during reproduction is measured by the error rate measuring means. The head mounting height can be measured from the error rate measurement result and the recording track height on the tape at that time. The error rate is based on the fact that the error rate during reproduction is extremely deteriorated when the reproducing head is slightly off the recording track.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows a positional relationship between a tape pattern of a magnetic tape and an enlarged portion of an audio recording track recorded on the magnetic tape of this embodiment and an audio reproducing head. Audio tracks 2a and 2b are audio recording tracks, 3 are video tracks, 4 are control tracks, 5 is an audio reproducing head, 6 is a reproducing amplifier, 7
Is a decoder, and 8 is an error rate meter.

Here, a 1-inch open reel high-definition digital VTR (hereinafter referred to as HD-DVTR)
The tape format and the audio playback head are described as examples.

In the HD-DVTR, the audio track 2 is recorded under the magnetic tape 1 in the longitudinal direction. As shown in FIG. 2, the audio recording head 9 for digitally recording on the audio track 2 and the audio reproducing head 5 are separate fixed heads. The track width of the audio reproducing head 5 is 190 μm, and the track width of the audio recording head 9 is The width is 360 μm, and the track width of the audio reproducing head 5 is narrower.

In the HD-DVTR, when the magnetic tape 1 is usually reproduced, the audio reproducing head 5 having the track width of 190 μm scans the inside of the audio track 2 having the track width of 360 μm, and the reproduced digital signal obtained is amplified by the audio amplifier 6. After being decoded by the decoder 7, the audio error rate at the time of reproduction can be displayed on the error rate meter 8. At this time, if the mounting position of the audio reproducing head 5 is deviated and reproduction is performed out of the audio track 2, the recording signal of the audio track 2 and other noises are also reproduced, and errors increase and the error rate deteriorates. .

Utilizing this phenomenon, a magnetic tape 1 is created by recording the audio track 2 by intentionally shifting the audio recording tracks 2a and 2b in a stepwise manner like an enlarged portion, and the error rate when the magnetic tape 1 is reproduced is produced. Sound recording track 2a having a good error rate by measuring
And the height of the sound recording track 2b at the point of deterioration, the mounting height of the sound reproducing head 5 can be measured.

In this example, the tape is produced with the amount of deviation between the audio recording track 2a and the audio recording track 2b being 10 μm each.

FIG. 3 shows a graph of the height from the lower end of the tape to the lower end of the audio recording track at this time versus the error rate.

As for the height of the audio recording track, the data of the height of the audio recording track corresponding to each of the audio recording tracks recorded stepwise in a one-to-one manner is recorded on the tape, and the HD- The display panel of the DVTR can be confirmed in real time.

The height of the audio recording track 2a in FIG.
00 μm, the height of the audio recording track 2b is 1010 μm
When the magnetic tape 1 is reproduced by the audio reproducing head 5, the height of the audio recording track gradually increases stepwise, but the audio reproducing head 5 reaches the audio recording track 2a.
Has a good error rate because it scans the inside of the audio recording track, but the audio reproducing head 5 extends beyond the audio recording track from the audio recording track 2b, and the error rate suddenly deteriorates.

It can be seen from the graph of FIG. 3 that the error rate is good up to 1000 μm, so that the mounting height of the audio reproducing head 5 at this time is 1000 μm or more and less than 1010 μm.

The measurement accuracy at this time is 10 μm, but the accuracy is improved as the deviation amount of the audio recording track is made finer when the tape is produced.

Further, in this example, the audio recording track is recorded in a step-like manner rising to the right and the lower end of the audio reproducing head is measured. However, it is recorded in a step-like manner descending to the right and the upper end of the audio reproducing head is also measured. The height of the midpoint between the lower end and the upper end of the reproducing head may be obtained from the average value.

[0021]

According to the present invention, the mounting height can be easily and accurately quantitatively measured simply by reproducing with the magnetic recording / reproducing apparatus.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a magnetic recording / reproducing apparatus of the present invention.

FIG. 3 is an explanatory diagram of an error rate change of the present invention.

[Explanation of symbols]

 1 ... Magnetic tape, 2 ... Audio track, 2a, 2b ... Audio recording track, 5 ... Audio reproducing head, 8 ... Error rate meter.

Claims (2)

[Claims] 1. A method of measuring a mounting height of a head for reproducing a recording track recorded on a magnetic tape in a longitudinal direction as a digital signal, wherein the recording track is preliminarily set to a plurality of predetermined heights and the track width of the reproducing head is set. A head mounting height measuring method, characterized in that a tape recorded by shifting with a narrower amount is reproduced, and a mounting height of the reproducing head is measured from a change point of an error rate during reproduction. 2. A method for measuring the mounting height of a head for reproducing a recording track recorded with a digital signal in the longitudinal direction on a magnetic tape, wherein the height of the recording track is continuously stepwise to 1 / the head track width. A reproducing head that reproduces a tape recorded by shifting it by N widths (N is an integer of 2 or more), and from the height of the recording track recorded on the tape when the error rate during reproduction exceeds a specified value. A measuring method characterized by measuring the mounting height of the.