JPS62283440A - Automatic tracking device for magnetic recording medium - Google Patents

Abstract

PURPOSE:To stabilize the tracking with an optional quantity of offset by deciding the offset quantity of a pilot signal by only the amplification factor with respect to the summation of adjacent pilot signals, to apply simple and accurate decision. CONSTITUTION:A recording and reproducing head 3 is traced along a track recorded in a magnetic recording medium, respective pilot signals P1, P2 are outputted from an LPF 14 from preceding and succeeding tracks adjacent to the both sides of the track during tracing, and the signals P1, P2 are subject to 1st sample-holding 16. The signals P1, P2 are added by an adder section 17, the added signals P1+P2 is fed to an amplifier 18, where the signal is subject to amplification processing by 1/(alpha+1) time. The amplified signal 1/ (alpha+1)(P1+P2) are fed to a differential section 21, an error signal from the differential section 21 is fed to a capstan motor 24 via a 2nd sample and holding circuit 22 to control the motor 24, thereby stabilizing the tracking at an optional offset.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention, such as a rotary head type digital audio recorder, traces a head along a track of a magnetic recording medium on which image or audio data is recorded as PCM, and the ATF signal area of the track is During after-recording, in which a new data signal is recorded over the area where the PCM data signal was recorded, the head traces the ATF area of the track and reproduces the ATF signal, while simultaneously recording the ATF area of two adjacent tracks. Pilot signal components P1 and P2 are obtained from the signal domain, and their level difference (P, -
This relates to ATF tracking that performs tracking control based on P2).

Conventionally, when signal tracks are recorded diagonally on a magnetic tape using a helical scan type rotary head device, and the recording/reproducing head is traced along the track to reproduce the recorded signal, it is necessary to align the head correctly with the l/rack. In order to trace the
In addition to the data signal area (1) where signals are recorded, low frequency ATF signal areas (2H2) are provided before and after the data signal area (1), and when the head is tracing, pilot signals are received from two adjacent tracks, leading and trailing. A racking method (ATF) is known that picks up pilot signals P1 and P2 and controls the drive of the capstan motor so that the strengths of both pilot signals P and 22 are equal (Japanese Patent Application Laid-Open No. 112406/1983).

In this ATF tracking, the track width is 20μ
m, whereas the head gap of the recording/reproducing head is 26μ...For example, in Fig. 2, head (3) is 8μ.
When tracing the 0 track, simultaneously trace the leading and trailing tracks A adjacent on both sides. and A, also from, ATF
It can pick up signals.

The ATF signal area includes a synchronization signal recording section S, an erasure signal recording section e, and a pilot signal recording section p, and when the head receives a synchronization signal from track B0, it starts recording the following track A. The pilot signal P2 is picked up from the previous track A, then the preceding track P is picked up, and the phase of the tape is controlled so that the levels of the two pilot signals P+ and P2 are made equal.

Two recording/reproducing heads are symmetrically installed on the cylinder, and each head has a different azimuth angle to separate data signals for each track to prevent data signals from being mixed in from adjacent tracks. In this case, since the frequency is in the low range, no azimuth effect occurs, and it is possible to sample the ATF signal from both tracks at the same time as tracing.

According to the above device, when reproducing a data signal,
ATF tracking allows the head to accurately trace the center of the track.

However, when performing after-recording on a track where a data signal has already been recorded, leaving the ATF signal area where it is, overlapping it with the PCM data signal in the data recording area, or rewriting the subcode recording area, the center of the head There is a problem in that the data signal is traced off the center of the existing track, and the after-recorded data signal is recorded off the traced track. The reason for this is as shown in FIG. 5. Assuming that the head (3) correctly traces the center of the data recording area of the first track B0, the data recording area tli(
1) is recorded.

Next, when tracing the second track 80, head (3)
Since the signal is recorded with a width of 26μ steel across the 1st and 31st tracks B0 and B, the signal is recorded with a width of 26μ steel.
In this case, the track width is narrowed by 3 μm on one side, and the center of the track is shifted by 1.5 μm.

(Prior art) Various methods have been proposed for offset tracking during after-recording.
~ Adding a constant DC bias (offset voltage △e) to the trailing side of the Byrond signal sampled from the rack, an error voltage is formed by e = P + (Pz + Δe), and the pilot voltage P1 on the leading side increases P, = When the P2 model Δe is e・0, the tracking center of the head coincides with the center of the existing track (Japanese Patent Application No. 6O-76976), and the pilot signal P2 on the trailing side is multiplied by α (α 〉1), an error signal is formed by e=PI-αP2, and when the pilot signal P of the preceding track increases until P+=αP2, e=o.
There is a method of aligning the center of head tracking with the existing track.

However, in the former case where a constant DC bias voltage is applied, the strength of the recording current of the existing track, the recording/reproducing ability of the head,
Or, even though magnetic tape characteristics vary in each case, -
It was found that if a regular DC bias voltage Δe was applied, there would be a problem in correct tracking.

In the latter method, which amplifies the trailing pilot signal, as the error amount increases, as shown in Figure 4, when the head moves to an adjacent track, the state becomes closer to a stable state, so the error voltage decreases and the error is reduced. The proportional relationship between the amount and the error voltage no longer holds, and the ATF tracking control becomes unstable.

Also, the tracking is shifted and the fluctuation of the pilot voltage becomes Δe.
Then, the error voltage is e=(P,+Δe)-α(P2-Δe); (α+1)
80 (', 'P, = αp2), and the actual error voltage is 2△e, so as the offset becomes larger and the value of α is set higher, the error voltage e becomes an inaccurate value. The proportional relationship between the error amount and the error voltage does not hold, and the tracking differs from normal reproduction side tracking.

(Means for Solving the Problems) In the present invention, the error voltage is formed according to the relationship (where α>l), that is, two pilot signals P1 and P2 are input to the adder, and the added pilot signal P2 and was input to the differential section, and the error signal output from the differential section was input to the magnetic recording medium drive device to control the track signal of the magnetic recording medium to the recording/reproducing head.

(Made by Kawa) The relational expression for the above error signal can be summarized as follows.

Among the two pilot signals P1 and P2, when P increases α times higher than P2 and reaches the magnitude of P, = αP2, e・
0, and tracking is performed stably.

Further, when the tracking is deviated and the pilot voltage fluctuates by Δe as shown by the broken line in FIG. 3a, the error voltage becomes as follows.

When P, reaches α times the size of P2, P, = αP2
Therefore, the above equation becomes e=Δe, and the error voltage is proportional to the amount of tracking deviation.

(effect) In the present invention, the offset amount of the pilot signal is P.

Any offset amount α can be set, as long as it is easy to implement, and is within the error amount of the straight line part of the graph in Figure 4.
Tracking is possible without instability.

<Example> In this example, as an example of a recording medium, signal tracks are recorded diagonally on a magnetic tape, and helical scanning is performed using a pair of magnetic heads (3) installed at symmetrical positions on a cylinder rotating at high speed. It traces the track.

A pulse generator (7) is provided for the motor (6) that drives the head (3), and a pulse generator (8) sends a signal indicating the reference cylinder phase every half rotation of the motor.
), and as shown in Figure 3 a and b, the first period T, , T
, a sampling pulse is emitted to the first, which will be described later.
It is added to the second sample and hold circuits (16) and (22). A pair of heads switch alternately to perform the same function,
Since signals are continuously recorded and reproduced, only one head will be explained.

The head (3) sends and receives signals via a rotary transformer, and data signals such as audio and images are converted into PCM by a recording signal processing circuit (10) and sent to an amplifier circuit (11).
), and is input to the first switch (9). The first switch (9) is switched by the computer, and the head (3) is conducted to the A side during recording, and to the B side during playback. conducts to.

When the first switch (9) is conducting to the b side, the reproduced signal from the head (3) is input to the amplifier circuit (12) and the reproduced signal processing circuit (13) in order, and the PCM signal is converted to analog. be done.

In the case of after-recording according to the present invention, while the head is tracing the ATF signal area (2) of the track, the first switch (9) conducts l, (II!l/\\ and AT
F tracking is performed and the head is in the data signal area (1
) is made conductive to the a side during tracing, and signals are overwritten in the data signal area of the tape track.

Head (3) is B. While tracing the ATF signal area of the track, the playback signal from the head is amplified by the amplifier circuit (12), passes through the low-pass filter (14) to separate the ATF signal, and then passes through the rectifier circuit (15). envelope detection is performed.

The output from the rectifier circuit (15) is input to the first sample and hold circuit (16), and at the same time the output is input to the pulse generator (7).
After emitting the reference pulse, the sampling pulse T2 is emitted during the T2 period shown in FIG.
16).

At that point, the head is picking up the ATF signal from the trailing track, and the rectifier circuit outputs a pilot signal P2, which is sampled and input to the adder (17).

During the next period T, the head picks up the ATF' signal from the preceding track, and the rectifier circuit 1 (15) outputs the pilot signal P, which is input to the adder (17) and the first sample bold circuit ( 16) to form the (PI+P2) signal.

The output signals P and +P2 of the adder (17) are sent to the amplifier (18)
It can be any value above, but a range of 1 to 9 is desirable.

(19) and the tip f! - Branched in parallel with the installed resistor (20) and inputted to the differential section (21), compared with the pilot signal P2 from the first sample and hold circuit (16), and outputs a difference signal. The difference signal is input to the second sample hold circuit (22), and the pulse forming circuit (8) is inputted to the second sample hold circuit (22).
It is sampled by the T1 pulse emitted during one period and output as an error signal e, )(・Sofa amplifier (
23), the capstan motor (24) is controlled.

Next, the other head is A. When tracing the trunk, as shown in FIG. 3C and d, during the period T0, the pilot signal P is sent from A to the t-rack. and then period 1f
When il T , , T , the samples (
Rus T2. T, from the adjacent truck) Kuiro・
point signal P2. PL is obtained, and from these, an error signal e is generated using the circuit configuration described above.

The error signal may be formed by using values obtained by amplifying the relational signals P + and P 2 with the same amplification factor.

Summer -1z7+ and λ1. ) P = + (Pl-P
7), resulting in normal ATF tracking.

By making the value of α variable, the offset amount can be adjusted to an optimal value.

Furthermore, the signal input to the differential section (21>) is replaced with 22!
By setting the output P of the first current circuit (15), the error signal can be set to P, and the Byrond signal to be subtracted can be selected depending on the polarity of the error voltage required for the system.

In the above embodiment, the magnetic tape is traced by a pair of heads, and while the head is tracing the ATF signal area, the first switch (6) f! :This is an example of switching to the b side for reproduction, and when tracing a data signal area, switching to the a side for signal recording, but the present invention is not limited to the above embodiments, and as shown in FIG. The read-only head (26) is installed in advance of the recording/playback head (3), and while the read-only head (26) is tracing the ATF signal area of the track,
Detects the pilot signal and forms error No. 13, controls the cab stan motor, and then controls the recording/reproducing head (
3) When tracing a track, the head can be aligned with the center of the original track on which the signal has been recorded correctly so that recording is performed in the data signal recording area of the track (Japanese Patent Application No. 6O-160906).

In this case, the circuit configuration is as shown in FIG. 7, and the portion downstream from the low-pass filter (14) is the same as the embodiment shown in FIG.

The present invention is not limited to the configurations shown in the drawings and description;
Naturally, many modifications can be made within the scope of the claims.

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration diagram of an embodiment of the present invention, FIG. 2 is an explanatory diagram of the signal area of a magnetic tape track, and FIGS. 3 a to 3 d are explanatory diagrams of a pilot signal and sample timing pulse output from the head. FIG. 4 is a graph showing the relationship between the amount of tracking error and the error voltage at that time. FIG. A plan view showing the structure of the cylinder and head of the embodiment, and FIG. 7 is a circuit configuration diagram of the embodiment of FIG. 6. (1)...Data signal recording area (2)...ATF signal recording area (3)...Record/playback head (16)...First sample and hold circuit <17)...
-Addition section (18)...Amplification section (21)...Differential section (22)...Second sample bold circuit (24)...
・Capstan motor applicant Sanyo Electric Co., Ltd. Head° B, A, BoA, B. Figure 2 2 Da Figure 6 Figure 4 Procedure "FFn Original [Method] September 2/1, 1985 1, Incident Display n Lighting 61 1.267172, Title of Invention Automatic Trunking of Magnetic Recording Media device 3,
Person making the amendment Applicant (188) Sanyo Electric Co., Ltd. Column 6 for a brief explanation of the drawings in the Mei IvII document Date of procedural amendment order August 26, 1985 (shipping date) or later

Claims (3)

[Claims] (1) A recording/reproducing head is traced along a track recorded on a magnetic recording medium, and pilot signals P_1 and P_2 are sampled from the preceding and following tracks, respectively, which are adjacent to both sides of the track being traced. Two pilot signals P_1 and P_2 are input to the adder, and the added signal P_1+P_2 is added to the amplifier and 1/(α+1
) times the amplification process and the amplified signal 1/(α+1)(
P_1+P_2) and one pilot signal P_1 or P
_2 is input to a differential section, and an error signal output from the differential section is input to a magnetic recording medium drive device to control the track position of the magnetic recording medium with respect to the recording/reproducing head. automatic tracking device. (2) The recording/reproducing head moves to A of the track to be traced.
2. The apparatus according to claim 1, wherein in a TF signal area, pilot signals are sampled from adjacent preceding and following tracks to form an error signal, and in a PCM signal area of a track, a new switch is made to record a PCM signal. (3) The recording/reproducing head is composed of a recording/reproducing head placed on a cylinder that rotates at high speed, and a read-only head placed slightly ahead of the recording/reproducing head, and the read-only heads are on both sides of the track being traced. pilot signals P from the leading and trailing trucks adjacent to the
2. The apparatus according to claim 1, wherein the recording/reproducing head samples the signals P_1 and P_2, and traces the center of the original track on which the signal has been recorded, with the tracing position of the recording/reproducing head being controlled by an error signal.