JPS62154353A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To attain the automatic identification of a reproduced tape where plural tracking systems mix by measuring the signal length of a tracking pilot signal and identifying the recording state of the tape based on said signal length. CONSTITUTION:A change in a recording track pattern due to a change in the travel speed of the tape mainly appears as the time lengths of tracking signals f1-f4, and a change in the signal length of the pilot signal f1 is the most prominent. After the signal recorded on the magnetic tape is reproduced by a rotating magnetic head 2, and amplified by an amplifier 3, it inputs to a BPF 4 passing only the frequency of the pilot signal f1. While the pilot signal f1 appears, a signal B is outputted from an envelope detection circuit 5. A clock signal C is generated from a clock generator circuit 6. A counter 7 counts said clock signal while the output signal of the envelope detection circuit 5 appears, inputs it as the signal length of the pilot signal f1 to an identification circuit 8, whose output signal controls the travel speed of the magnetic tape.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording/reproducing apparatus, and more particularly to automatic identification of a recorded state during reproduction in a rotary head type magnetic recording/reproducing apparatus.

[Prior Art] As is well known, in a rotary head type magnetic recording/reproducing device, tracking control is performed to ensure that the rotary head correctly scans the recording track of a magnetic tape during reproduction.

Conventionally, as a method for this tracking control, during recording, a control signal recorded on one end of the tape in the width direction by a fixed magnetic head is reproduced by the fixed head, and this reproduction control signal and the rotational phase of the rotary head are kept constant. Control is performed to maintain a phase relationship. Further, the recording state of the magnetic tape is usually identified by measuring the period of the control signal, and the tape running speed and the like are controlled.

However, in the conventional method described above, since a fixed magnetic head must be provided especially for tracking control, a space must be secured for its installation, which poses a problem when it is desired to downsize the magnetic recording/reproducing device. .

Therefore, a method of performing tracking control without using a fixed magnetic head has been proposed, for example, in Japanese Patent Laid-Open No. 59-112406.

This method converts the signal to be recorded into PCM, and when recording and reproducing in a so-called overwritten state, that is, without forming a guard band between tracks, the PCM signal is applied to a part of each diagonal track. Tracking pilot signals are recorded independently from the above, and when the three consecutive tracks are viewed from a direction perpendicular to the scanning direction of the rotary head, the recording positions of the pilot signals of the respective tracks do not overlap with each other. When the recording track is scanned by a rotary head whose gap width is wider than the width of the track during reproduction, the reproduction rotary head is activated by the reproduction output of the pilot signal from the tracks on both sides of the track to be scanned. The system is designed to perform tracking control.

FIG. 4 is a recording pattern diagram in the tracking method disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 59-112406,
In the figure, P T 1. P T2. P T3 indicates a pilot signal region, and STI and Sr1 indicate a PCM region.

FIG. 5 shows P T l, P T2 . shown in FIG. 4. P T
3, P is a pilot signal for tracking, E is a signal for erasing, tp is a track pitch, H is a rotating head, and arrow (1) indicates the scanning direction of the rotating head H.

According to this tracking control, there is no need to specifically provide a fixed magnetic head for tracking control, so there is an advantage that miniaturization can be realized.

[Problems to be Solved by the Invention] However, in the magnetic recording/reproducing device of the above-mentioned Japanese Patent Application Laid-Open No. 59-112406, there is no problem when the recording format of the tracking method is one type, but for example, the running speed of the tape If there are multiple types of recording formats for the tracking method due to differences in the recording formats, etc., there is a problem that the method cannot be applied as is.

This invention was made to solve the above-mentioned problems, and it is possible to automatically identify when playing back a tape in which a plurality of types of tracking methods coexist.

Moreover, it is an object of the present invention to provide a magnetic recording/reproducing device that can realize this automatic identification with a simple circuit.

[Means for Solving the Problems] A magnetic recording and reproducing device according to the present invention includes a rotating magnetic head that reads signals recorded on diagonal tracks on a magnetic tape without forming a guard band, and this rotating magnetic head. means for measuring the signal length of the pilot signal for tracking among the signals read by the measuring means, and an identification circuit for identifying the recording state of the magnetic tape based on the output of the measuring means, It is characterized by controlling the running speed of the magnetic tape.

[Operation] In the present invention, the recording state of the tape is identified by reading the tracking pilot signal recorded on the magnetic tape with a rotating magnetic head and measuring the signal length of the reproduced pilot signal. ing.

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

FIG. 1 is a block circuit diagram showing an embodiment of the present invention. In FIG. 0, (2) is a rotating magnetic head, (3) is an amplifier that amplifies the reproduction output of the rotating magnetic head (2),
) is a bandpass filter that passes only the pilot signal from the output of the amplifier (3), and (5) is a bandpass filter that passes the signal (B in the figure) only during the period when the output (A in the figure) of the bandpass filter (4) appears. Envelope detection circuit to generate (6
) is a clock generation circuit that generates a clock signal (C in the figure) based on the output of the bandpass filter (4); (
7) is a counter that counts the period during which the output of the envelope detection circuit (5) appears (B in the figure) using a clock (C in the figure), and (8) determines the recording state of the tape from the counting result of the counter (7). This is an identification circuit that performs identification.

The bandpass filter (4), envelope detection circuit (5), clock generation circuit (6), and counter (7) constitute the signal length measuring means of the pilot signal in the present invention.

FIG. 2 is an example of a recording track pattern of a tracking method used to explain an embodiment of the present invention.
FIG. 3 is an example of a recording track pattern of a tracking method that can cope with an increase in tape running speed, based on the recording track pattern of FIG. 2.

In the figure, the recording signal is recorded on diagonal tracks on the magnetic tape without forming a guard band.
fl is a pilot signal with a frequency of 130.67K HZ,
f2 is a synchronization signal with a frequency of 522.87KHz, and f3 is a frequency fi? 84. oOK is a synchronization signal of Hz, and f4 is a cancellation signal of frequency 1.588 MHz. Further, arrow (9) indicates the scanning direction of the rotating magnetic head, and arrow (10) indicates the running direction of the magnetic tape.

As can be seen by comparing FIG. 2 and FIG. 3, changes in the recording track pattern due to changes in tape running speed are mainly caused by tracking signals fl and f2.
, f3, and f4, but not in the recording order.

In FIG. 2, the signal length of the pilot signal f1 is, for example, two blocks, while in FIG. 3, it is, for example, three blocks, and it can be seen that the change in the signal length of the pilot signal f1 is remarkable.

Next, regarding a method of identifying the recording state of a signal by keeping the signal length of the pilot signal f1 constant J,
This will be explained with reference to FIG.

In FIG. 1, the signals shown in FIGS. 2 and 3 recorded on a magnetic tape (not shown) are reproduced by a magnetic head (2), amplified by an amplifier (3), and then converted into a pilot signal f1. The signal is input to a bandpass filter (4) that passes only the frequency.

Here, the pilot signal fl (A in the figure) that has passed through the bandpass filter (4) is passed through the envelope detection circuit (
5), and the envelope detection circuit (5) outputs a signal (Fig.
) is output.

The pilot signal fl that has passed through the bandpass filter (4) is also input to the clock generation circuit (6), and this input causes the clock generation circuit (8) to generate a clock signal (C in the figure).

This clock signal is input to a counter (7), and the counter (7) counts the clock signal C while the output signal of the envelope detection circuit (5) is appearing.

This counting result is input to the identification circuit (8) as the signal length of the pilot signal fl, and the identification circuit (8) identifies the recording state of the signal based on the signal length of the pilot signal f1. The running speed of the magnetic tape is controlled by the output signal from this identification circuit (8).

In the above embodiment, the bandpass filter (4) is used to pass the pilot signal fl, but if the pilot signal fl has the lowest frequency among the tracking signals, a lowpass filter may be used.

Further, in the above embodiment, the clock signal is generated based on the pilot (δ number f1), but this is not necessarily necessary, and an external clock signal may be used.

[Effects of the Invention] As described above, according to the present invention, the signal length of the pilot signal for tracking is measured and the recording state of the tape is identified based on this signal length, so that multiple tracking methods can be used. It is possible to automatically identify when playing back a tape containing a mixture of It has the effect of giving you something.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a magnetic recording/reproducing wave according to an embodiment of the present invention, and FIGS. 2 and 3 are recording track patterns of a tracking method used to explain an embodiment of the present invention. FIG. 4 is a diagram showing an example of a recording track pattern in a conventional tracking method, and FIG. 5 is a diagram for explaining details of the recording track pattern of FIG. 4. (2)...Rotating magnetic head, (4)...Band pass filter, (5)...Envelope detection circuit, (8)
... Clock generation circuit, (7) ... Counter 2 (8
)...Identification circuit, fl...Pilot signal. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (2)

[Claims] (1) A rotating magnetic head that reads signals recorded on diagonal tracks on a magnetic tape without forming a guard band, and measuring the signal length of a pilot signal for tracking among the signals read by this rotating magnetic head. means and
A magnetic recording and reproducing apparatus comprising: an identification circuit for identifying the recording state of the magnetic tape based on the output of the measuring means, and controlling the running speed of the magnetic tape based on the output of the identification circuit. (2) The signal length measuring means for the pilot signal includes a filter through which only the pilot signal can pass, an envelope detection circuit that generates an output during the period in which the pilot signal appears based on the output of the filter, and an output of the filter. 2. The magnetic recording and reproducing apparatus according to claim 1, further comprising: a clock generation circuit that generates a clock signal based on the clock signal; and a counter that counts the clock signal during the period of the output signal of the envelope detection circuit.