JPH0749649Y2 - Magnetic recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a magnetic recording / reproducing apparatus for recording a PCM signal while forming an oblique track on a recording medium by a rotary head every unit time and reproducing the same.

(Prior Art) Conventionally, a method of recording an audio signal converted into PCM on a magnetic tape by a rotary head of a helical scan type has been considered. The device based on this method is a magnetic recording and reproducing device generally called a digital audio tape recorder (DAT).

The PCM signal used in this device is a discrete value and can be easily compressed and expanded on the time axis. Therefore, unlike an analog signal, it is not necessary to record and reproduce while always maintaining temporal continuity.

FIG. 3 is a diagram for explaining a recording track pattern recorded on the magnetic tape.

The PCM signal is compressed on the time axis and is recorded by forming tracks diagonally on the recording medium in a state in which multiple rotary heads do not form a guard band. , A pilot signal f ₁ , independent of the PCM signal, timing signals f ₂ and f ₃ having different frequencies in adjacent tracks and different recording lengths, and an erase signal f ₄ are repeatedly recorded in a predetermined track pattern.

During reproduction, when the rotary head scans on the track pattern, a sampling pulse for sampling the pilot signal f ₁ of the adjacent track is formed based on the start ends of the timing signals f ₂ and f ₃ , and this pulse is generated. During this period, the crosstalk component of the pilot signal f ₁ from the adjacent track is detected, and the phase control of the capstan that transfers the magnetic tape by a predetermined amount is performed based on the tracking error detection signal which is the detection output. .

FIG. 4 is a block diagram of a conventional magnetic recording / reproducing apparatus.

As shown in the figure, in the conventional magnetic recording / reproducing apparatus, 1a and 1b are rotary heads, 2 are capstans, 3 are capstan motors, 4 are pinch rollers, 5 are drum motors, 6 and 15 are switching circuits, and 7 are switching circuits. Is a reproduction amplifier, 8 is a low-pass filter, 9 and 10 are band-pass filters, 11 is an envelope detection circuit, and 12 and 1
4 sample and hold circuit, 13 is a differential amplifier, 16 a comparator, the sampling pulse generation circuit 17, a head switching signal generation circuit 19, 20 to 23 f ₁ ~f ₄ recording timing signal generator circuit, 24 to 27 is the f _{1 to} f ₄ signal generation circuit, 28 is the OR
A circuit, 29 is a recording amplifier having a control terminal capable of controlling the gain of an output signal, 30, 31 are phase servo circuits, 32 is a frequency generator, and T is a magnetic tape. The first and second timing signal generating circuits are f ₁ and f ₄ recording timing signal generating circuits 20, and the first and second signal generating circuits are f ₁ and f ₄ signal generating circuits.
24,27.

FIGS. 5 (A) to 5 (H) are diagrams showing timing signals of respective parts of the block configuration shown in FIG.

Next, the recording / reproducing operation of this apparatus will be described.

During recording The positions of the rotary heads 1a and 1b are output from the head switching signal generating circuit 19 by a drum rotation phase servo system including a frequency generator 32, a head switching signal generating circuit 19, a phase servo circuit 30 and a drum motor 5. Head switching signal RF
It is synchronized with SWP (shown in FIG. 5 (A)). Further, based on the signal RFSWP, are generated timing signals TP1~TP4 from the timing generating circuit 20 to 23, according to these timing signals, the signal f ₁ ~f ₄ from the signal generating circuit 24 to 27 is generated, these After being amplified by the recording amplifier 29 via the OR circuit 28, it is supplied to the rotary heads 1a and 1b via the switching circuit 6 and recorded on the magnetic tape T. The first and second timing signals are timing signals TP1 and TP4.

At the time of reproduction The signals reproduced by the rotary heads 1a and 1b (the signals a and b shown in FIGS. 7B and 7C) are supplied to the reproduction amplifier 7 via the switching circuit 6 and after being amplified here. , Low-pass filter 8 and band-pass filters 9 and 10. In the reproduction signal supplied to the low-pass filter 8, only the pilot signal f ₁ (shown in FIG. 3D) is extracted here, and then the envelope detection circuit 11 detects the reproduced signal. Differential amplifier through
It is applied to the + input terminal of 13 and the detected signal is applied to the-input terminal of the differential amplifier 13. The reproduction signals supplied from the reproduction amplifier 7 to the bandpass filters 9 and 10 are the timing signals f ₂ and f ₃ (shown in (E) and (F) in the figure).
After being taken out only, through the switching circuit 15 that is switched by the signal supplied from the head switching signal generation circuit 19,
Comparator with one input terminal having a predetermined potential
It is supplied to the other 16 input terminals. The comparison output signal from the comparator 16 is supplied to the sampling pulse generating circuits 17 and 18, where the two sampling pulses SP1 and SP2
And supply this signal to the sample and hold circuits 12 and 14. The tracking detection signal output from the sample hold circuit 14 obtained by comparing the detection output of the crosstalk of the pilot signal f ₁ from the adjacent track with the timing signals f ₂ and f ₃ is the phase servo circuit 31 and the capstan. Tracking control during reproduction is performed by controlling the rotational phase of the capstan 2 via the motor 3.

Here, the pilot signal f ₁ is selected to have a low frequency, for example, 130.67 kHz, which can obtain a sufficient reproduction output from adjacent tracks having different azimuth angles, and the timing signals f ₂ and f ₃ can be easily distinguished from the pilot signal f _1. A frequency at which azimuth loss can be expected to some extent, for example, 522.67 kHz, 784 kHz is selected, and the erase signal f ₄ is easy to distinguish from these, and the frequency with a high erase rate when overwritten with the signals f _{1 to} f ₃ , for example, 1.568 MHz. Has been selected.

(Problems to be Solved by the Invention) The conventional magnetic recording / reproducing apparatus described above does not have an independent erasing head like the known VTR, but performs recording while performing overwriting erasing using a rotary head. Therefore, in the case of performing overwrite erasure using a rotary head on a magnetic tape, it is most preferable to erase the pilot signal f ₁ of long wavelength (λ≈24 μm) with the erase signal f ₄ of short wavelength (λ≈2 μm). It is hard to erase, and usually only an erasing rate of 10 to 13 dB can be obtained.

On the other hand, the pilot signal f ₁ picked up by the rotating head during reproduction from the main track on which the rotary head is running and the track adjacent to
As shown in FIGS. 6 (A) and 6 (B), the amount of crosstalk is compared with the pilot signal f ₁ reproduced from the main track by, for example, -7 to -9 dB (determined by the head shape or head width, etc.). Considering that it is a signal of about (value), the above-mentioned erasing rate cannot be said to be a sufficient value.

Furthermore, when the recording depth changes due to the magnetoelectric conversion efficiency of the rotary head or the variation in the recording current, the overwriting side has a deep recording depth, and the overwriting side has a shallow recording depth. There is a problem that a sufficient erasing rate cannot be obtained and tracking control during reproduction is affected.

(Means for Solving Problems) In order to solve the above-mentioned problems, the present invention relates to a magnetic recording / reproducing apparatus, in which PCM data obtained by pulse-code modulating an information signal to be recorded and a predetermined period of time are provided. A recording signal composed of a tracking detection signal including at least a pilot signal and an erasing signal, which is positioned before and after the PCM data, is sequentially recorded on the magnetic recording medium by forming a track on the magnetic recording medium. A magnetic recording / reproducing apparatus for performing tracking control of a capstan for controlling traveling of the magnetic recording medium by scanning on a track and reproducing the recording signal, wherein a switching signal for switching the rotary head during recording is used. First and second timings for generating first and second timing signals for generating the pilot signal and the cancellation signal based on A signal generation circuit, and first and second signal generation for generating the pilot signal and the erase signal based on the first and second timing signals from the first and second timing signal generation circuits A circuit and an amplifier circuit for amplifying at least the pilot signal and the erase signal and adjusting the output gain thereof in accordance with the second timing signal are employed.

(Example) The magnetic recording reproducing apparatus according to the present invention, at the time of recording, particularly by increasing only the write current of the erasing signal f _4, to improve the erasability of the pilot signal f ₁ at the time of overwriting, the tracking during reproduction It is intended to stabilize and improve the control.

FIG. 1 is a block diagram of a magnetic recording / reproducing apparatus according to the present invention.

The same components as those described above are designated by the same reference numerals, and the description thereof will be omitted.

The magnetic recording / reproducing apparatus according to the present invention has the configuration shown in FIG. _{4 with} the output side of the f ₄ recording timing signal generating circuit 23 and the control input terminal of the recording amplifier 29 connected. The other structure is the same as that shown in FIG.

FIGS. 2 (A) to 2 (D) are diagrams showing timing signals of respective parts of the block configuration shown in FIG.

The recording operation is performed as follows.

The positions of the rotary heads 1a and 1b are synchronized with the head switching signal RFSWP (shown in FIG. 2A) by the drum rotary phase servo system described above. With reference to the head switching signal RFSWP, timing signal TP1~TP4 is generated during the time the signal TP1~TP4 is output, the signal f ₁ ~f ₄ is generated, the recording amplifier via the OR circuit 28 Supplied to 29. The reproduced signal reproduced from the rotary heads 1a and 1b is the signal shown in FIG.

The timing TP4 indicating a period for recording the erase signal f ₄
(Shown in (C) of the figure) is directly applied to the control terminal for adjusting the gain of the output signal of the recording amplifier 29, and the recording current of the recording signal (shown in (D) of the figure) is increased during this period.

Therefore, the recording signal output from the recording amplifier 29 has an increased recording signal level only during the period when the erasing signal f ₄ is generated, and this changes through the switching circuit 6 to the rotary heads 1a, 1b.
And is recorded on the magnetic tape T.

In addition, although it will not be described in detail here that the recording signal level increases only when the erase signal of the frequency f ₄ is generated, the PCM area in which the PCM signal shown in FIG. 3 and the signal f ₁ are recorded. , f ₂ and f ₄ are provided with an IBG area having the same frequency as the erase signal f _{4 in} order to give a margin to the positional accuracy when rewriting only the data to be recorded in the PCM area. It is also easy to increase the gain of the recording current output from the recording amplifier 29 only during the period when the IBG area and the erase signal f ₄ are generated.

Since the reproducing operation is the same as that shown in FIG. 4, the description thereof is omitted here.

(Effects of the Invention) As described above, the magnetic recording / reproducing apparatus according to the present invention has a long wavelength when performing overwriting erasure using the rotary head, regardless of the magnetoelectric conversion efficiency of the rotary head and variations in the recording current. The pilot signal f ₁ signal (λ≈24 μm) can be erased by a signal including the erase signal f ₄ having a short wavelength (λ≈2 μm), so that the erasing rate can be improved, so that stable overwriting can be performed. Therefore, there is an effect that the tracking control at the time of reproduction can be always maintained stably.

[Brief description of drawings]

FIG. 1 is a block diagram of a magnetic recording / reproducing apparatus according to the present invention, FIGS. 2 (A) to 2 (D) are diagrams showing timing signals of respective parts of the block configuration shown in FIG. 1, and FIG. For explaining the recording track pattern recorded in FIG. 4, FIG. 4 is a block diagram of a conventional magnetic recording / reproducing apparatus, and FIGS. 5 (A) to 5 (H) are timing charts of various parts of the block shown in FIG. Diagram showing signals, FIGS. 6 (A) and 6 (B)
FIG. 6 is a diagram showing a pilot signal f ₁ reproduced from a main track and an adjacent track. 1a, 1b …… Rotating head, 2 …… Capstan, 20,21,22,
23 …… f _{1 to} f ₄ Recording timing signal generation circuit, 24, 24, 26, 2
7 …… f _{1 to} f ₄ signal generating circuit, 29 …… Recording amplifier (amplifying circuit), T …… Magnetic tape (magnetic recording medium), RFSWP ……
Switching signal, f ₁ ... Pilot signal, f ₄ ... Delete signal.

Claims (1)

[Scope of utility model registration request] 1. Recording comprising PCM data obtained by pulse-code modulating an information signal to be recorded, and a tracking detection signal located before and after the PCM data for a predetermined period and containing at least a pilot signal and an erase signal. A signal is sequentially recorded on a magnetic recording medium by a rotary head to form a track, and at the time of reproduction, scanning of the rotary head over the track to reproduce the recording signal controls the running of the magnetic recording medium. A magnetic recording / reproducing apparatus for performing tracking control of a capstan, wherein during recording, first and second timing signals for generating the pilot signal and the erase signal are generated based on a switching signal for switching the rotary head. First and second timing signal generation circuits, and the first and second timing signal generation circuits from the first and second timing signal generation circuits First and second signal generating circuits for generating the pilot signal and the erasing signal based on the second timing signal; at least amplifying the pilot signal and the erasing signal, and the second timing signal And erasing the pilot signal already recorded on the magnetic recording medium by increasing only the recording current of the erase signal amplified by the amplifier circuit. A magnetic recording / reproducing apparatus characterized by improving the rate.