JPH0777073B2 - Digital magnetic recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a digital apparatus for performing reproduction by progressive scanning of at least two rotary magnetic heads having different azimuth angles, such as a rotary head type digital audio tape recorder. The present invention relates to a magnetic recording / reproducing device.

[Prior Art] FIG. 4 is a schematic view of a main part of a conventional rotary head type digital magnetic recording / reproducing apparatus. In FIG. 4, (1) is a tape-shaped recording medium, and (2) is a rotary magnetic head. Then,
It is composed of two heads (HA) and (HB) having different azimuth angles, and records and reproduces a main signal such as a video signal in the case of a video tape recorder on the recording medium (1). (3) is an erase head for recording a search code such as a cue signal. (4) is a queue for reproducing the search code such as a cue signal.

Next, the operation of the digital magnetic recording / reproducing apparatus having the above configuration will be described.

At the time of recording, the recording medium (1) has a rotating magnetic head (2).
Simultaneously with the recording of the main signal by, the erase head (3) deep-records a search code such as a cue signal at a frequency sufficiently lower than the main signal (generally several 10 HZ) in the form of frequency multiplexing.

When reproducing the medium (1) recorded in such a state,
In the normal reproduction, the search code is reproduced together with the main signal by the rotating magnetic head (2), but the frequency of the search code is very low and is less than the processing band of the main signal. There is almost no adverse effect on reproduction.

On the other hand, at the time of high-speed reproduction such as cueing, the search code is reproduced at the cu-head (4) at a speed several tens of times faster than the normal reproduction in a traveling state in which the recording medium (1) is not in contact with the rotating magnetic head (2). .

[Problems to be Solved by the Invention] Since the conventional rotary head type magnetic recording / reproducing apparatus is configured as described above, in order to realize high-speed reproduction such as high-speed cueing, a fixed head dedicated thereto is provided. Is required, and the overall configuration becomes complicated.

Further, the conventional device does not have a function of reproducing the main signal recorded by the rotary magnetic head at the time of high-speed reproduction, and search information is recorded only by the rotary magnetic head like a digital audio tape recorder. There was a problem such as not being able to support the tape specifications that were in place.

The present invention has been made to solve the above-mentioned problems, and it is possible to perform high-speed search by reading search information such as a head search recorded in a main signal by a rotary magnetic head without using a dedicated head. Moreover, it is an object of the present invention to provide a digital magnetic recording / reproducing apparatus capable of accurately reproducing only a search code recorded in an area division together with an audio signal as a main signal as an effective signal during the high speed search.

[Means for Solving Problems] A digital magnetic recording / reproducing apparatus according to the present invention has at least two rotating magnetic disks having different azimuth angles with respect to a recording medium in which a search code is recorded in a predetermined area. Playback is performed by sequentially scanning the head, and PL
In a digital magnetic recording / reproducing apparatus that generates a reproduction clock synchronized with the reproduction signal by the L circuit and demodulates the reproduction signal into the original data by using the reproduction clock by the demodulation circuit, from the rotating magnetic head during high-speed reproduction. Of the reproduction signal of (1) is envelope-detected and the waveform is shaped through a low-pass filter to detect the recording area of the same azimuth as the reproducing head being scanned, and a rotary drum to which the rotary magnetic head is attached. And a search code area detecting means for detecting an area in which a search code is recorded as a wind pulse using the drum PG pulse synchronized with the rotation of the reference signal, and a recording area of the same azimuth as the reproducing head being scanned, and , Except for the area where the search code is recorded, the demodulation is performed by the gate circuit. The clock or reproducing data transfer of the PLL circuit to the road is obtained by so and a gate means for inhibiting.

[Operation] In the present invention, not only the above search code area but also the rotary magnetic head is currently scanning at the time of high speed reproduction,
By detecting the reproduction area of the reproduction head and the same azimuth and using it as the data acquisition condition required for high-speed search, only the area of the above-mentioned search code area at which the signal is accurately reproduced is searched. Will be done.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit block diagram of a digital magnetic recording / reproducing apparatus according to an embodiment of the present invention. In FIG.
(1) is a tape-shaped recording medium, and as shown in FIG. 2, a signal track (T) is recorded at a predetermined azimuth angle for each field. Search code areas (SUB-1) and (SUB-2) are formed at predetermined positions in each signal track (T) by area division, and these area (SUB-1) and (SUB-2) are formed. The information such as the beginning signal for a few seconds, the song number, the hour, the minute, and the second is recorded as a digital signal in the. (2) is a rotating magnetic head,
It is composed of two heads (HA) and (HB) having different azimuth angles and is mounted on a rotary drum (9) around which the tape-shaped recording medium (1) is wound. (5) is a reproduction amplifier for amplifying a weak electric signal reproduced by the rotating magnetic head (2), (6) is an envelope detection circuit for AM detecting the envelope waveform output from the reproduction amplifier (5),
(7) is a low-pass filter that removes unnecessary high frequency components, and (8) is a waveform shaping circuit that converts an analog signal into a pulse signal of 1,0. The envelope detection circuit (6) and the low-pass filter (7) ), Wave shaping circuit (8)
Thus, the same azimuth area detection means (18) for detecting the recording area of the same azimuth as the scanning reproducing head is constituted. Also, (10) is the reproduction amplifier (5).
A data detection circuit for converting the analog signal output from the above into a pulse signal of 1,0, (11) amplifies a head switch signal (hereinafter referred to as drum PG signal) reproduced from the rotating drum (9), and outputs a pulse signal. A drum PG sense amplifier for converting into a drum PG sense amplifier, (12) a drum FG signal sense amplifier for amplifying a rotation pulse signal (hereinafter referred to as a drum FG signal) reproduced from the rotating drum (9), and (13) a drum PG signal. A shift register for delaying data as a data by a drum FG signal, (14) is a gate circuit for generating a window by the output from the shift register (13), and the shift register (13) and the gate circuit (14)
Search code area detecting means (19) for detecting, as a window pulse, an area in which a search code is recorded using a drum PG pulse synchronized with the rotation of the rotary drum (9) having the rotary magnetic head (2) as a reference signal. Is configured. Further, (15) is a PLL circuit that generates a clock synchronized with the reproduced data from the data output from the data detection circuit (10), and (16) controls the clock generated by the PLL circuit (15). As a result, it is a recording area of the same azimuth as the reproducing head that is scanning,
And, except the area where the search code is recorded, the gate circuit that prohibits the transfer of the clock of the PLL circuit (15) to the demodulation circuit (17), (17) converts the digitally modulated signal to the original data Demodulation circuit.

The operation of the digital magnetic recording / reproducing apparatus having the above configuration will be described in the second
Description will be made with reference to the track pattern and head locus of the recording medium shown in the figure and the signal waveform diagram of each part shown in FIG.

In the state of FIG. 1, by sequentially scanning the recording medium (1) with two rotating magnetic heads (HA) and (HB) having different azimuth angles, in the normal reproduction mode, (Y) of FIG.
As shown in, the two rotating magnetic heads (HA) and (H
B) alternately scans on each signal track (T) recorded at a predetermined azimuth angle for each field.

Thus, in the normal playback mode, each track (T)
A predetermined azimuth head is selected for each, and information such as the music number can be reliably obtained from the two search code areas (SUB-1) and (SUB-2).

However, in high-speed playback mode, for example, when rewinding,
The rotary heads (HA) and (HB) scan across a plurality of signal tracks (T) as shown by the hatched line (X) in FIG. Therefore, the signal output from the reproduction amplifier (5) has an envelope waveform as shown in FIG. The shaded area in FIG. 3 (a) is the area of the same azimuth as the head currently being scanned, and is the area where a normal signal is reproduced. It is possible to extract only a normal signal area by detecting the shaded portion and applying a gate to the reproduction signal. Therefore, the third
The signal of FIG. 3A is input to the envelope detection circuit 6 and AM-detected, and the low-pass filter 7 outputs the periodic waveform of the cross track shown in FIG. 3B.

The signal (b) is then supplied to the waveform shaping circuit (8), where the threshold level (T) shown in FIG.
H), and as a result, the output side is shown in Fig. 3 (c).
A pulsed signal as shown in can be taken out. As a result, the high level in the pulse signal can be detected as the portion where the normal signal is reproduced.

As described above, only the normal reproduction signal area can be extracted.

On the other hand, in an apparatus for recording / reproducing a signal using the rotating magnetic head (2), in order to read the signal recorded on the track in the high-speed reproducing state, the relative speed of the recording medium (1) and the rotating magnetic head (2) is to be read. Must be kept constant.
For that purpose, for example, when performing high-speed reproduction in the rewinding state, it is necessary to increase the feeding speed of the recording medium (1) and decrease the speed of the rotating magnetic head (2). That is, the rotational speed of the rotary drum (9) to which the rotary magnetic head (2) is attached must be reduced. As a result, the reproduction cycle of the search code areas (SUB-1) and (SUB-2) shown in FIG. 2 becomes proportional to the rotation speed of the rotary drum (9).

Further, in reproducing the signal recorded on the tape-shaped recording medium (1), detecting it by the data detecting circuit (10) and processing the digital signal, a means for temporarily storing the information in the RAM is used. For that purpose, it is necessary to extract the writing area of the RAM, and the drum PG pulse generated by the sensor element provided in the rotary drum (9) is used to monitor the output timing of the reproduction signal. That is,
This means that the processing timing of the reproduction signal is determined based on the conversion point of the drum PG pulse.

However, as mentioned above, (SUB-
The areas of 1) and (SUB-2) are proportional to the number of rotations of the drum (3). Therefore, those playback areas should be extracted with a fixed clock such as a crystal with the conversion point of the PG pulse as the reference. It is difficult.

The means for accurately extracting the areas of (SUB-1) and (SUB-2) in the above state will be specifically described below.

In FIG. 1, a sensor element such as a Hall element is attached to the rotary drum (9) for the purpose of detecting the rotational phase of the drum (9), and the signal of this sensor element is sent to the drum PG amplifier (11). After being input and amplified, it is output as a pulsed signal as shown in FIG. In order to control the rotation speed of the rotating drum (9), the drum (9) is magnetized with several tens of poles, and the MR element or the like reproduces the magnetized signal.
Drum FG signal is generated. This drum FG signal is a drum
After being input to the FG sense amplifier (12) and amplified, the third
It is converted into a pulse-shaped signal as shown in FIG. As a result, the drum PG pulse and the drum FG pulse are synchronized with the rotation speed of the drum (9).

In other words, the drum PG pulse is used as data and the drum FG pulse is used as the shift clock and is input to the shift register (13), and its outputs (Q1), (Q2), (Q3), (Q4) are output to the third
In the gate circuit (14) as shown in Figure (f), (SUB-1),
By generating the (SUB-2) window pulse, an accurate (SUB-
It is possible to extract areas 1) and (SUB-2).

The pulse shown in FIG. 3 (c) and the window pulse shown in FIG. 3 (f) for detecting the cycle of the cross track obtained as described above are shown in FIG. 3 (g) by the PLL (15).
A gate (16) is used for the clock generated as
By enabling as shown in FIG. 3 (i),
The data transmission after the demodulation circuit (17) is stopped, and only the accurate and necessary search code as information is input to the digital signal processing circuit.

The search code reproduced as described above is transmitted / received to / from the microcomputer controlling the system from the digital signal processing circuit, and its timing is executed in the high area of FIG. 3 (f). As a result, data transmission is performed in accordance with the rotation speed of the drum, that is, the inspection speed.

As described above, according to the above-described embodiment, reproduction is performed by sequentially scanning at least two rotary magnetic heads having different azimuth angles on the recording medium in which the search code is recorded in the predetermined area. In a digital magnetic recording / reproducing apparatus in which a reproduction clock synchronized with the reproduction signal is generated by the PLL circuit, and the reproduction signal is demodulated to the original data by the demodulation circuit, the rotary magnetic head during high-speed reproduction. Envelope-detects the reproduction signal from, and shapes the waveform through a low-pass filter to detect the recording area of the same azimuth as the reproducing head that is scanning, and synchronize with the rotation of the rotary drum with the rotary magnetic head attached. Using the drum PG pulse as a reference signal and the area where the search code is recorded as a window pulse Then, except for the recording area of the same azimuth as the reproducing head that is scanning and the search code is recorded, the clock of the PLL circuit or the reproduction data transfer to the demodulation circuit is performed by the gate circuit. Since it is prohibited, it is possible to perform high-speed search such as cueing using a rotary magnetic head for normal reproduction, and it is possible to eliminate the need for a head dedicated to high-speed search.

It is also possible to process only the high-speed search information that is normally reproduced, so that it is possible to overlook code errors that occur in areas where the SN is low or in audio areas that are unnecessary for search, and error correction code errors. Corrections can be improved, and highly accurate and high-speed search can be realized.

Furthermore, the area in which the search code is recorded uses the drum PG pulse as data, the drum FG signal synchronized with the drum PG pulse is input to the shift register as the shift clock, and the output of the shift register is input to the gate circuit. The processing to generate and detect a window pulse allows the search code area to be always detected accurately even with respect to the rotating drum fluctuation caused by the constant relative speed control during high-speed search, ensuring a search error. Can be prevented.

In the above embodiment, the means for detecting the reproduction area of the same azimuth as the reproduction head currently being scanned is detected by the reproduction envelope. The same effect can be obtained even if the state is set to the same azimuth area.

Further, as the means for searching the data, the means for stopping the clock of the PLL is shown, but the same effect can be obtained by prohibiting the data transfer as the search information after decoding the reproduced signal.

[Advantages of the Invention] As described above, according to the digital magnetic recording / reproducing apparatus of the present invention, at least two different azimuth angles are recorded on a recording medium in which a search code is recorded in a predetermined area. Digital magnetic recording in which reproduction is performed by sequentially scanning the rotary magnetic head, a reproduction clock synchronized with the reproduction signal is generated by the PLL circuit, and the reproduction signal is demodulated to the original data by the demodulation circuit. In the reproducing device, at the time of high speed reproduction, the reproduction signal from the rotary magnetic head is envelope-detected and the waveform is shaped through a low-pass filter to detect the recording area of the same azimuth as the reproducing head being scanned. The detection means and the drum PG pulse synchronized with the rotation of the rotary drum with the rotary magnetic head attached Search code area detection means for detecting an area in which the search code is recorded as a quasi-signal as a window pulse, and a recording area of the same azimuth as the reproducing head being scanned, and the search code is recorded. Except for the area, the PL to the demodulation circuit is controlled by the gate circuit.
Since the clock of the L circuit or the gate for prohibiting the reproduction data transfer is provided as a means, it is possible to perform high-speed search such as cueing using the rotating magnetic head for normal reproduction, and it is dedicated for high-speed search. The head can be eliminated.
Moreover, since the data acquisition conditions necessary for such high-speed search are determined by the signal obtained from the original reproduction signal, it is necessary to always perform accurate detection of the search code area by following the search speed. Therefore, it is possible to reliably prevent a search error.

[Brief description of drawings]

FIG. 1 is a circuit block diagram of a digital magnetic recording / reproducing apparatus according to an embodiment of the present invention, FIG. 2 is a diagram for explaining a track pattern and a head locus of a recording medium, and FIG. 3 is a signal waveform diagram of each section during operation. FIG. 4 is a schematic view of a main part of a conventional digital magnetic recording device. (1) …… Recording medium, (2) …… Rotary magnetic head,
(5) ... Reproduction amplifier, (6) ... Envelope detection circuit, (7) ... Low pass filter, (8) ... Waveform shaping circuit, (9) ... Rotary drum, (10) ... Data detection circuit , (11) …… Drum PG sense amplifier, (12) …… Drum FG sense amplifier, (13) …… Shift register, (1
4), (16) …… Gate circuit, (15) …… PLL circuit, (1
7) ... Demodulation circuit, (18) ... Same azimuth area detection means, (19) ... Detection code area detection means. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (2)

[Claims] 1. A recording medium in which a search code is recorded in a predetermined area is reproduced by sequentially scanning at least two rotary magnetic heads having different azimuth angles, and is reproduced by a PLL circuit. In a digital magnetic recording / reproducing apparatus that generates a reproduction clock synchronized with a signal and demodulates the reproduction signal to the original data by using the reproduction clock, a reproduction signal from the rotary magnetic head is enveloped during high speed reproduction. By detecting and shaping the waveform through a low-pass filter, the same azimuth area detecting means for detecting the recording area of the same azimuth as the reproducing head being scanned, and the rotation of the rotary drum equipped with the rotary magnetic head are synchronized. The area where the search code is recorded using the drum PG pulse as the reference signal is the window pulse The search code area detecting means for detecting and the recording area of the same azimuth as the reproducing head being scanned, and the PLL circuit to the demodulation circuit by the gate circuit except the area where the search code is recorded. And a transfer prohibiting means for prohibiting the transfer of the clock or the reproduced data. 2. The search code area detecting means processes the output of the shift register and a shift register into which the drum PG pulse is data, and a drum FG signal synchronized with the drum PG pulse is input as a shift clock. A digital magnetic recording / reproducing apparatus according to claim 1, further comprising a gate circuit for generating a wind pulse.