JP2637720B2 - Magnetic recording / reproducing device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a magnetic recording / reproducing apparatus for recording / reproducing information with a rotating magnetic head such as a video tape recorder.

[Summary of the Invention]

According to the present invention, a first portion and a second portion are formed on a track inclined with respect to the longitudinal direction of a magnetic tape by a rotating magnetic head rotated at a first speed, and at least the first portion is further provided with a clock signal. Is recorded, a part b where data such as PCM audio signals are recorded, a margin part c for after recording, and a video overlap part d where the video signal of the immediately preceding field is continuously recorded. And the first part or the second part is PC
In a magnetic recording / reproducing apparatus for recording or reproducing an M audio signal or a video signal by frequency-multiplexing with a tracking pilot signal, a magnetic recording / reproducing apparatus rotates a magnetic tape longitudinally at a second speed higher than a first speed. A third portion for recording a first code signal, a fourth portion for recording a control signal for tracking, and a fifth portion for recording a PCM audio signal on a track inclined with respect to the direction.
, A sixth part for recording the control signal for tracking, and a seventh part for recording the second code signal, and the third to seventh parts each include a predetermined number of blocks. An eighth part for recording a third code signal having the same number of blocks as in the third part, and a PCM audio signal having the same number of blocks as in the fifth part, corresponding to the method of recording and reproducing data. And a fourth block having the same number of blocks as in the seventh section.
And a tenth portion for recording the code signal of the first and second portions, the rotating magnetic head is switched from the first speed to the second speed and rotated, and the inclined track including the first portion and the second portion is formed. It is divided into four areas, and information composed of the eighth, ninth and tenth parts is recorded and reproduced in each of the four areas, so that a higher-quality audio signal is recorded and reproduced in a so-called 8 mm video tape recorder. It is something that can be done.

[Conventional technology]

Recently, a so-called 8 mm video tape recorder has been standardized and commercialized. In this 8 mm video tape recorder, the rotating diameter of the rotating magnetic head (the diameter of the rotating drum) is 40 mm, and the winding angle of the magnetic tape on the rotating drum is 221.
It is a degree. A video signal is recorded in a portion corresponding to a winding angle of 180 degrees, and a PCM audio signal is recorded in a portion corresponding to a winding angle of 36 degrees (the remaining 5 degrees). Is the remainder). When the 36-degree portion is further subdivided, a portion a where a clock signal is recorded, a portion b where data such as a PCM audio signal is recorded, a margin portion c for after-recording, and a video portion of the immediately preceding field. The signal is divided into a video overlap portion d where signals are continuously recorded. Then, tracking pilot signals f ₁ , f ₂ , f ₃ , f ₄ are sequentially recorded for each track over the entire portion corresponding to the winding angle of 221 degrees. These pilot signals f ₁ , f ₂ ,
f ₃ and f ₄ are each, for example, f _H / 58, f _H / 50, f _H / 36, f _H / 40
(F _H is a horizontal synchronization signal). A tracking error signal is generated from crosstalk components from left and right tracks of a pilot signal continuously recorded on each track. The number of rotations of the rotating magnetic head is set to 1800 rpm in the NTSC system and 1500 rpm in the PAL system because a video signal is recorded. A plurality of (five) portions corresponding to a winding angle of 36 degrees are formed in a portion corresponding to a winding angle of 180 degrees, so that only an audio signal can be recorded.

Audio signals recorded on 36-degree portion, the sampling frequency is 2f _H (approximately 31.5k Hz), the number of quantization bits is converted records 10 bits of data to 8 bits on 10 bits (although the magnetic tape ), And the number of channels is two.

On the other hand, R-DAT has recently been standardized to record and reproduce audio signals on a magnetic tape with higher quality.
In R-DAT, the winding angle of the magnetic tape is 90 degrees, the diameter of the rotating drum is 30 mm, the sampling frequency is 48 kHz,
Either 44.1 kHz or 32 kHz, the number of quantization hits is 16 bits, and the number of channels is 2.

The track corresponding to the winding angle of 90 degrees is divided into 16 parts as shown in FIG. 4, and data is recorded in each part as shown in Table 1.

Note that fch is a clock signal having a frequency of 9.408 MHz.

As can be seen from Table 1, this data mainly consists of part 2,
3 and 4, and a sub-code signal recording unit composed of
7, a PCM audio signal recording section including portions 8 and 9, a tracking signal recording portion including portions 10, 11 and 12, and a subcode signal recording portion including portions 13, 14 and 15. It is configured.

[Problems to be Solved by the Invention] As described above, there are two methods for recording and reproducing a digital audio signal on a magnetic tape using a rotating magnetic head. However, an 8 mm video tape recorder originally records a video signal. Therefore, the sampling frequency of the audio signal is low, and the sound quality is inferior to that of the R-DAT. On the other hand, the R-DAT has a drawback that only an audio signal can be recorded and reproduced, and a video signal cannot be recorded and reproduced.

[Means for solving the problem]

FIG. 1 is a block diagram of a magnetic recording / reproducing apparatus (8 mm video tape recorder) of the present invention. In FIG. 1, reference numeral 1 denotes two rotating magnetic heads attached to a rotating drum (not shown) at a distance of 180 degrees from each other. A signal is supplied to the rotating magnetic head 1 from a recording amplifier 4 via switches 2 and 3. While being supplied alternately, a signal from the rotating magnetic head 1 is output to the reproducing amplifier 5 via the switches 2 and 3. The amplifier 4 is supplied with the signals from the video modulator 8 and the PCM encoder 9 via the switch 6 and the pilot signal output from the pilot signal generator 35. The signal from the regenerative amplifier 5 is connected to the video demodulator 10 via the switch 7.
It is output to the PCM decoder 11. Reference numerals 12 and 13 denote a PCM decoder and a PCM encoder corresponding to the R-DAT format.
The output is supplied to the decoder 12, and the output of the PCM encoder 13 is supplied to the recording amplifier 4 via the switch 6. Reference numeral 14 denotes an oscillator that generates a clock signal f′ch and outputs it to the PCM encoder 13.

Reference numeral 15 denotes a motor for rotating the rotary drum, which includes a frequency generator 16 and a pulse generator 17, and is driven by a drive circuit 18. The output of the frequency generator 16 is input to the frequency control circuit 19, is compared with a predetermined reference signal output by the built-in oscillation circuit, and outputs an error signal. 20
Is a phase control circuit, a vertical synchronization signal included in the video signal to be recorded separated by the synchronization separation circuit 22, a reference signal output by the oscillator 23, a reference signal output by the PCM decoder 12, or an output by the PCM encoder 13. One of the reference signals to be input as a reference signal via the switch 21 and the phase is compared with the pulse output from the pulse generator 17,
A signal corresponding to the error is output. The output of the frequency control circuit 19 and the output of the phase control circuit 20 are added by the adding circuit 24 and supplied to the drive circuit 18.

Reference numeral 25 denotes a motor for rotating a capstan (not shown), and includes a frequency generator 26. Frequency generator 26
Is supplied to a frequency control circuit 27 and a frequency dividing circuit 28. The frequency control circuit 27 compares a predetermined reference signal output from the built-in oscillation circuit with the output of the frequency generator 26, and outputs an error signal to the addition circuit 30. The frequency dividing circuit 28 divides the output of the frequency generator 26 and outputs it to the phase control circuit 29. The phase control circuit 29 compares the signal from the switch 21 with the signal from the frequency dividing circuit 28, and compares the error signal
The signal is output to the addition circuit 30 via 34. The addition circuit 30 adds the output of the frequency control circuit 27 and the output of the phase control circuit 29, and outputs the result to the drive circuit 31. The drive circuit 31 is a motor 25
Is to be driven. A tracking control circuit 32 separates and extracts a pilot signal from the output of the reproduction amplifier 5, generates a tracking error signal, and
The signal is output to the addition circuit 30 via 34. Reference numeral 33 denotes a central processing unit (CPU) such as a microcomputer, which controls each circuit, means, switches, etc. in connection with a main central processing unit (not shown).

[Operation] The operation will now be described. When a command for recording a normal video signal and an accompanying PCM audio signal is input, the CPU 33 transmits the frequency control circuits 19 and 27 and the drive circuit 1
A control signal is issued to 8, 31, etc., and the rotating drum is driven to the motor 15 at the standard speed (1800 rpm for NTSC system, 1500 for PAL system).
rpm), and the motor 25 rotates the capstan so that the speed of the magnetic tape (not shown) becomes a standard speed. At this time, the frequency control circuit 19
The servo is applied so that the frequency of the signal output by the controller becomes equal to the frequency of the built-in reference signal. At this time, the switch 21 is switched so as to select the output of the sync separation circuit 22, and the rotating drum is rotated so as to synchronize with the phase of the vertical sync signal in the video signal to be recorded. The phase control circuit 20 generates a head switching pulse (HSWP) as a reference for switching between the two rotating magnetic heads and outputs the pulse to each circuit.

Similarly, the frequency control circuit 27 and the phase control circuit 29 apply frequency servo and phase servo to the motor 25. At this time, the phase control circuit 29 supplies an error signal with the output of the frequency dividing circuit 28 to the adding circuit 30 via the switch 34 with reference to the output of the synchronization separating circuit 22 output from the switch 21. Therefore, the specified speed (14.345m / s for NTSC system, 2 for PAL system)
The speed of the magnetic tape is controlled to be 0.051 m / s).

The video signal to be recorded is input to a video modulator 8,
Frequency modulated. The audio signal to be recorded is PC
It is input to the M encoder 9 and digitized (PCM). These signals are transmitted through the switch 6 to the recording amplifier 4,
Further, it is supplied to the rotating magnetic head 1 via the switches 2 and 3 and recorded on the magnetic tape. With reference to the head switching pulse output from the phase control circuit 20, a video signal is recorded in the video signal recording section at 180 degrees, and an audio signal is recorded in the audio signal recording section at 36 degrees.
At this time, the tracking pilot signal generated by the pilot signal generator 35 is frequency-multiplexed and recorded on the video signal and the PCM audio signal. The frequency can be the same as the pilot signal in the case of the PAL system. This makes it easy to divide and generate the pilot signal from the clock signal f'ch.

When a video signal is reproduced, an output signal of the oscillator 23 (a signal corresponding to a vertical synchronization signal) is supplied to the phase control circuit 20 via the switch 21 as a reference signal. Further, the switch 34 is switched to the tracking control circuit 32 side, and the phase servo of the motor 25 is performed in accordance with the tracking error signal generated from the crosstalk component of the pilot signal recorded on the right and left adjacent tracks. The reproduced signal from the rotating magnetic head 1 is transmitted to the video demodulator 10 and the PCM decoder 1 via the switches 2 and 3, the reproducing amplifier 5 and the switch 7.
Entered into 1. Therefore, the video signal recorded in the 180-degree video signal recording unit and the audio signal recorded in the 36-degree audio signal recording unit are demodulated and output.

Next, when recording only a high-quality audio signal, the audio signal is input to the PCM encoder 13 and digitized. The PCM encoder 13 is a PC in a so-called R-DAT.
The same one as the M encoder can be used. Where P
The CM encoder 13 is controlled at a different timing by a different clock from that in the R-DAT.

That is, in the present invention, one track having a length corresponding to a winding angle of 221 degrees is divided into four regions having a length of 54 degrees as shown in FIG. A margin of 2.956 degrees is provided. The areas A to D having a length of 54 degrees are further divided into nine parts as shown in FIG. 3, and data is recorded in each part as shown in Table 2.

As is apparent from Table 2, in the present invention, the data recording sections 5, 6, 7, and 1 for tracking in Table 1 are used.
The format is such that 0, 11, 12, and the last margin part 16 are removed. The clock f
'ch is set to, for example, 12.864 MHz (= 0.048 MHz + 268). This frequency is the sampling frequency of the audio signal
This is an integer multiple of 48 kHz (= 0.048 MHz) and is appropriately selected from values near the highest recording frequency. Of course, the combination can be changed within a range where the winding angle is 54 degrees and the recording time is 4500 μs. For example, two blocks
Eliminate the PLL (PCM) clock recording section and set the margin section to 8.8
Can be changed to 10.8 blocks. Further, the remaining portions at both ends can be arbitrarily selected.

In this way, the already standardized R-DA
It is possible to record and reproduce information only by changing the timing without changing the coding of the T format.

The audio signal input to the PCM encoder 13 is digitized in accordance with the clock signal f'ch input from the oscillator 14, and its timing is controlled by the CPU 33 to be converted into a signal having a format as shown in Table 2. Is done. This signal is supplied to the rotary magnetic head 1 via the switch 6, the recording amplifier 4, and the switches 2, 3, and is recorded on the magnetic tape. At this time, an area pulse corresponding to at least one of the areas A to D is generated based on the head switching pulse output from the phase control circuit 20, and a signal is recorded in the area corresponding to the area pulse.

At this time, the frequency control circuit 19 and the drive circuit 18 are controlled by the CPU 33 so that the rotating drum rotates at 2000 rpm. The switch 21 is connected to the clock f output from the PCM encoder 13.
A signal synchronized with the 'ch is supplied to the phase control circuit 20 as a reference signal. Further, the frequency control circuit 27 and the drive circuit 31 are controlled in the same manner, and the speed of the magnetic tape is set to 10.025 m / s, which is half the standard speed of the PAL system of 20.51 m / s. When this speed is set, the track pitch becomes 13.3 μm, and NT
The width of the rotating magnetic head for the standard speed of the SC system or the rotating magnetic head for 1/2 speed thereof, and the width of the rotating magnetic head for the 1/2 speed of the standard speed of the PAL system are equal to the track pitch (13.3 μm).
m) is 1.5 to 2 times. Therefore, the recording and reproduction of the audio signal and the pilot signal can be performed without using the rotating magnetic head having a special width, and the tracking control by the crosstalk component of the pilot signal can be performed.

When reproducing the audio signal recorded in this way, a signal from the rotary magnetic head 1 is input to the reproduction amplifier 5 via the switches 2 and 3, and further supplied to the PCM decoder 12 via the switch 7. PCM decoder 12 is CPU3
3 to extract the clock f'ch from the reproduced signal,
The data of each part is read based on the reference. The audio signal is converted into an analog signal and output. A tracking pilot signal included in the reproduction signal is input to the tracking control circuit 32, and a tracking error signal is generated. This tracking error signal is output to the addition circuit 30 via the switch 34, and tracking control is performed. That is, in the R-DAT, as is clear from Table 1, a tracking signal (ATF) is recorded before and after the PCM audio signal recording unit, and a crosstalk component from that part of the left and right tracks is determined. The sample and hold is performed at the timing of, and a tracking error signal is generated from the difference signal. In the present invention, as in the case of a normal 8 mm video tape recorder, recording is continuously performed on each track. A tracking error signal is generated from a difference signal of crosstalk components from left and right tracks of the pilot signal.

In the same manner as in the case of the R-DAT, 16-bit audio signals of left and right two channels are recorded in one track in each of the four areas A to D. Therefore, for example, the running direction of the magnetic tape is reversed for each area, and areas A and C
Is the forward and backward recording, and the areas B and D are the recording and reproducing areas in the case of the backward feeding, it is possible to continuously record and reproduce on the tracks formed every four areas.

Also, for example, regions A and C are for the left channel, and regions B and D
For the right channel, the left and right channels can be recorded and reproduced independently.

If the sampling frequency is doubled (96 kHz) and data of the upper 8 bits and lower 8 bits or data of the left and right channels is recorded and reproduced for each area, a higher quality audio signal can be recorded and reproduced. Further, the sampling frequency can be quadrupled, and data of 4 bits can be recorded and reproduced in each area. In addition, it is also possible to use four channels, one set of two areas, six channels, one set of three areas, and eight channels, one set of four areas.

〔effect〕

As described above, the present invention forms the first portion and the second portion on the track inclined with respect to the longitudinal direction of the magnetic tape by the rotating magnetic head rotated at the first speed, and forms at least the first portion. Further, a portion where a clock signal is recorded
And a part b where data such as a PCM audio signal is recorded
And a margin c for after-recording,
The video signal is divided into a video overlap portion d in which the video signal of the immediately preceding field is continuously recorded, and a first portion or a second portion.
In a magnetic recording / reproducing apparatus which records or reproduces a PCM audio signal or a video signal by frequency multiplexing with a tracking pilot signal in a portion, a rotating magnetic head rotated at a second speed higher than a first speed. A third portion for recording a first code signal, a fourth portion for recording a control signal for tracking, and a fifth portion for recording a PCM audio signal on a track inclined with respect to the longitudinal direction of the tape. And a sixth part for recording a control signal for tracking and a seventh part for recording a second code signal. Data of a predetermined number of blocks are respectively stored in the third to seventh parts. According to the recording / reproducing method, the third
An eighth part for recording the same number of blocks of the third code signal as in the case of the fifth part, a ninth part for recording the PCM audio signal of the same number of blocks as in the fifth part, and a seventh part And a tenth portion for recording a fourth code signal of the same number of blocks as in the case of the above. The rotating magnetic head is switched from the first speed to the second speed and rotated, and the first portion and the tenth portion are rotated. Since the inclined track consisting of the second part is divided into four areas and the information consisting of the eighth, ninth and tenth parts is recorded and reproduced in each of the four areas, a so-called 8 mm video tape recorder is used. In addition to video signals, high-quality (high fidelity) audio signals can be recorded and reproduced.

[Brief description of the drawings]

FIG. 1 is a block diagram of a magnetic recording / reproducing apparatus according to the present invention.
FIG. 3 is a schematic plan view of the tracking, FIG. 3 is a schematic plan view of the area, and FIG. 4 is a schematic plan view of a track in the conventional magnetic recording / reproducing apparatus. 1 Rotary magnetic head 2,3,6,7,21,34 Switch 4 Recording amplifier 5 Reproduction amplifier 8 Video modulator 9,13 PCM encoder 10 Video demodulator 11, 12 PCM decoder 14, 23 ... Oscillator 15, 25 ... Motor 16, 26 ... Frequency generator 17 ... Pulse generator 18, 31 ... Driving circuit 19, 27 ... Frequency control circuit 20, 29 ... Phase control circuit 22 ... Sync separation circuit 24, 30 ... Addition circuit 28 ... Division circuit 32 ... Tracking control circuit 33 ... Central processing unit 35 ... Pilot signal generator

Claims (6)

(57) [Claims] A first portion and a second portion formed on a track inclined with respect to a longitudinal direction of a magnetic tape by a rotating magnetic head rotated at a first speed;
And a part a where a clock signal is further recorded and a PC
M is divided into a portion b where data such as an audio signal is recorded, a margin portion c for after-recording, and a video overlap portion d where the video signal of the immediately preceding field is continuously recorded. A magnetic recording / reproducing apparatus for recording or reproducing a frequency-multiplexed PCM audio signal or video signal on a portion or the second portion with a tracking pilot signal, wherein the second portion rotates at a second speed higher than the first speed. A third portion for recording a first code signal on a track inclined with respect to the longitudinal direction of the magnetic tape by the rotating magnetic head to be driven;
A fourth part for recording a control signal for tracking, and a PC
A fifth part for recording an M audio signal, a sixth part for recording a control signal for tracking, and a seventh part for recording a second code signal are formed.
Corresponding to a method of recording and reproducing a predetermined number of blocks of data in each of the portions, an eighth portion for recording a third code signal having the same number of blocks as in the third portion, PC with the same number of blocks as in the part
Forming a ninth part for recording M audio signals and a tenth part for recording a fourth code signal of the same number of blocks as in the seventh part; Switching from a speed to the second speed and rotating, and dividing the inclined track including the first portion and the second portion into four regions;
A magnetic recording / reproducing apparatus characterized in that information comprising the eighth, ninth, and tenth portions is frequency-multiplexed with the pilot signal for tracking in each of the four areas and recorded / reproduced. 2. The running speed of the magnetic tape is 1/2 of a standard speed when recording and reproducing the PCM audio signal and the video signal in the first portion and the second portion by the PAL system. 2. The magnetic recording / reproducing apparatus according to claim 1, wherein: 3. The audio signal having a sampling frequency twice as high as the sampling frequency of the audio signal recorded in the fifth portion is recorded and reproduced in two areas. 3. The magnetic recording / reproducing apparatus according to claim 1 or 2. 4. The audio signal having a sampling frequency four times the sampling frequency of the audio signal recorded in the fifth portion is recorded and reproduced in four areas. 3. The magnetic recording / reproducing apparatus according to claim 1 or 2. 5. The magnetic device according to claim 1, wherein only one audio signal of the left or right channel is recorded / reproduced in one area. Recording and playback device. 6. The pilot signal has the same frequency as the pilot signal when recording and reproducing the PCM audio signal and the video signal in the first part and the second part in the PAL system. A magnetic recording / reproducing apparatus according to any one of claims 1 to 5, characterized in that: