JPS61115220A - Magnetic head characteristic measuring device - Google Patents

Abstract

PURPOSE:To measure the electromagnetic characteristics of head and tape systems without overlapping with a high accuracy by a simple method by interrupting a recording signal supplied to each magnetic head for the prescribed period and insuring adjacent tracks from overlapping. CONSTITUTION:In the measuring device of a magnetic recording and reproducing device which detects a signal level from adjacent tracks and executes tracking servo, first the magnetic head 5 of a CH1 records the track of a track width W1 on a magnetic tape 7. Here, since the recording signal supplied to the magnetic head 5 is interrupted by a recording signal interrupting circuit 12 for the period T2, the recording signal is omitted in some area of the 1st track 1. Then the magnetic head 6 of a CH2 records the track of a track width W2 at the position where a recording track pitch goes to TP. Also in this case, since the signal supplied to the magnetic head 6 is interrupted by a recording signal interrupting circuit 13 for the periods T3 and T5, the recording signal is omitted in some area of the 2nd track 2. Accordingly signal recorded parts of these tracks will no overlap.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic head characteristic measuring device for measuring electromagnetic conversion characteristics of a magnetic head and magnetic tape.

[Conventional technology]

FIG. 5 is a diagram showing a recording pattern according to the conventional magnetic recording and reproducing method disclosed in Japanese Patent Application Laid-Open No. 53-1) 6120. In the figure, 5 is a magnetic head of channel (hereinafter abbreviated as CH) 1. , 6 is the magnetic head of CH2, 7 is the magnetic tape, 1 to 4 are the first to fourth recording tracks, and the first to fourth recording tracks are the first to fourth recording tracks. The third recording track 1.3 receives a recording signal from the CHI magnetic helad 5, and the second recording track 1. Fourth recording track 2
．． 4, a recording signal by the magnetic herad 6 of CH2 is recorded.

In such a system, one of the magnetic heads 5, for example, CHI, is used to record fl and third tracks on the first track 1.
Track 3 has the pilot signal of [3, and also CH2
f2. The pilot signal of f4 is mixed with the video signal and recorded on the fourth track 4. During playback, the signals on each track are read out using the same head used during recording, but since the track width of the head is larger than the track width of the recording track, adjacent signals on both sides are also read out at the same time. Third track 3 with magnetic head 5
When playing T2. from the second track 2. The pilot signal T4 is simultaneously read out from the fourth track 4, and the pilot signal f2. CH due to the level difference of f4
The positional deviation of the magnetic head 5 of I on the track 3 is detected.

Similarly, when reproducing the second track 2 with the magnetic head 6 of CH2, the biloft signals fl and f3 of the adjacent tracks 1.3 are read out, and due to the level difference, the biloft signals fl and f3 of the adjacent tracks 1.3 are read out. Detect positional deviation. In this way, positional deviations in each track are detected, and tracking servo is applied based on the detection results.

[Problem that the invention seeks to solve]

However, such conventional magnetic recording and reproducing systems have a drawback in that it is not possible to measure the electromagnetic conversion characteristics of the head and tape system when the recording tracks do not overlap.

This invention was made to solve the above-mentioned problems, and its purpose is to provide a magnetic head characteristic measuring device that can measure the electromagnetic conversion characteristics of a head and tape system when adjacent recording tracks do not overlap. do.

[Means for solving problems]

The magnetic head characteristic measuring device according to the present invention forms recording tracks by cutting off recording signals supplied to each magnetic head for a predetermined period so that adjacent recording tracks do not overlap.

[Effect]

In this invention, the recording signal of each magnetic head is cut off for a predetermined period of time, tracks are formed so that adjacent recording tracks do not overlap, and the pilot signal of the adjacent recording track is read out during reproduction, and the tracking servo for reproduction is applied. It also makes it possible.

〔Example〕

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

FIG. 1 is a block diagram of a signal E green circuit of a magnetic head characteristic measuring device according to an embodiment of the present invention.
．． 6 is a pair of magnetic heads attached to a rotating drum 8; 9 and 10 are terminals to which a recording current processed by the recording system of the VTR (not shown) is input when this device is built into a VTR; 1) is a rotating drum; Terminals 14.15 and 12.13 respectively receive the synchronous pulses from the rotary drum 8 and generate control pulses, and 12.13 and 12.13 respectively are the pulse generating circuits 14.1.
a recording signal cutoff circuit that cuts off the recording signal supplied to the magnetic heads 5 and 6 for a predetermined time by control pulses from 7;
is magnetic tape. Note that the reproduction system of the apparatus is completely the same as the conventional one and is well known, so a description thereof will be omitted here.

FIG. 2 shows a timing chart during recording. In the figure, f1 to r4 are biloft signals, each of which is mixed with a video signal, and these signals are interrupted twice during the contact period between the magnetic head and the magnetic tape. That is, signals are recorded in the CHI magnetic head 5 during the period T1, and the signal is recorded during the period T1.
The signal is cut off for a period of 2. Also CH2 magnetic herad 6
The signals are recorded in the period T4° and T6, and the signal is recorded in the period T3. T
The signal is cut off for a period of 5.

Here, the pitch of the recording track is Tp, the angle between the end of the recording track and the tape running direction is θ (see Figure 3), the relative speed between the magnetic head and the magnetic tape is vh, and the period T3~ T6 is T3-Tl+ΔT.

T4-T2-2ΔT, T5=T1+2ΔT, T6-T2
-ΔT is determined.

Next, the effects will be explained. FIG. 3 shows a recording track pattern when measuring magnetic head characteristics according to this embodiment.

First, a track having a track width W1 is recorded on the magnetic tape 7 by the CHI magnetic head 5. In this embodiment, since the recording signal supplied to the magnetic head 5 is cut off for the period T2 by the recording signal cutoff circuit 12 (see FIG. 2), as shown in FIG.
Recorded signals are missing in some areas. Next, a track with a track width W2 is recorded by the CH2 magnetic head 6 at a position where the recording track pitch is Tp. Here, in this case as well, since the signal supplied to the magnetic head 6 is cut off by the recording signal cutoff circuit 13 during the T3 and T5 periods (see FIG. 2) in the same manner as described above, a partial area of the second track 2 The recorded signal is lost. Therefore, the signal recording portions of these tracks do not overlap as shown in Fig. 3, and if the reproduced signals of such recorded tracks are input to the reproduction system of a conventional magnetic head characteristic measuring device, it will be possible to detect when there is no overlap. It is possible to measure the electromagnetic conversion characteristics of heads and tape systems.

Furthermore, when a recording track as described above is reproduced, a reproduced signal as shown in FIG. 4 is obtained. That is, for example, CHI
When the third track 3 is reproduced by the magnetic head 5, a signal of the track width Wl is obtained in the first period T1, and a signal of the track width Wl is obtained in the next period T2. Biloft signal f2. of fourth track 2, 4. Reads f4, but
The viroft signal read out in time is different and T2
The first 2ΔT period of the period is the pilot signal f4 from the fourth track 4, and the next (T2-4ΔT) period is the second . The biloft signal [2, T4 from the fourth track 2.4, and the biloft signal f2· from the second track 2 are sequentially reproduced during the final period of 2ΔT. In the next T1 period, a signal with track width W1 is obtained again, and in the next T2 period, the first 2ΔT period, the pilot signal f4 from the fourth track 4 is obtained, and the next (T2-
3ΔT) is the second period. Pilot signal f2. from fourth track 2.4. f4 and the final ΔT period, the biloft signal f2 from the second track 2 is sequentially reproduced. In this way, the pilot signal f2. from the adjacent track 2.4. The time that f4 is played is (2T
2-4ΔT) and (2T2-3ΔT).

On the other hand, the second track 2 is read by the magnetic head 6 of CH2.
When reproducing T3. 2T1. in each period of T5. It is reproduced for a period of (2T1-ΔT).

Here, the pilot signal pair to be compared f2. f4 and f
l and T3 each have a period difference of ΔT as described above, but for example, in the case of an 8 mm video tape recorder, ΔT-
62 μsec, and this period is T 1+ 72 (!
5m5ec). In this way, ΔT is T1. It can be made much smaller than T2, and therefore, this difference in ΔT does not affect tracking servo, and tracking servo can be applied based on the level difference of the pilot signals.

If you want to measure the head characteristics when there is no overlap using a conventional device that does not perform tracking servo, you must cut off the recording signal of one of the pair of magnetic heads and measure the head characteristics one by one. However, such a measurement method cannot be used in a VTR that performs tracking servo using pilot pulse signals from both adjacent tracks. Head characteristics can be measured easily and in a short period of time, and tracking servo can also be performed.

In the above embodiment, the recording current is cut off twice for each track, but it may be cut off three or more times, and the same effect as in the above embodiment can be obtained.

Alternatively, the period for recording and interrupting the recording signal of the pair of magnetic heads may be set to ΔT, and the recording signal may be interrupted by repeating recording and interrupting with the pair of heads at the same timing.
The same effects as in the above embodiment are achieved.

〔Effect of the invention〕

As described above, according to the present invention, in a magnetic recording and reproducing apparatus that performs tracking servo using signals from adjacent left and right tracks, when measuring magnetic head characteristics,
The recording signal supplied to each magnetic head is cut off for a predetermined period to prevent adjacent tracks from overlapping.
The electromagnetic conversion characteristics of the head and tape system when there is no overlap can be measured with high precision and with a simple method.
This has the effect of facilitating the maintenance and inspection work of the magnetic head and shortening the time.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a signal recording circuit of a magnetic head characteristic measuring device according to an embodiment of the present invention, FIG. 2 is a timing chart of recording signals of the device, and FIG. 3 is a diagram of a recording track pattern by the device. FIG. 4 is a timing chart of reproduction signals of the apparatus, and FIG. 5 is a diagram showing a recording track pattern according to a conventional magnetic recording/reproduction method. 1-4... Recording track, 5.6... -CHl, 2 magnetic head, 12.13... Recording signal cutoff circuit, 14.
15...Pulse generation circuit. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] (1) In a magnetic head characteristic measuring device for a magnetic recording/reproducing device in which a recording track is formed by overlapping a pair of magnetic heads during recording, and tracking servo is performed by detecting signal levels from adjacent left and right tracks during reproduction. . A magnetic head characteristic measuring device, characterized in that, when measuring the magnetic head characteristics, each of the recording signals by the pair of magnetic heads is recorded with a portion omitted so that adjacent recording tracks do not overlap.