JPH0633557Y2 - Rotary head type digital signal recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a rotary head type digital signal recording / reproducing apparatus.

(Prior Art) A rotary head type digital audio tape recorder (DAT) according to the present invention includes a PCM audio data for a certain period obtained by pulse code modulation of an audio signal and a PCM audio data before and after a predetermined period. Tracking detection signal (Automatic Tr
ACK Finding, ATF signal) has a recording function of recording tracks by sequentially forming tracks one by one on a magnetic tape by a rotary head, and a reproducing function of reproducing the recorded multiple signals.

The magnetization pattern recorded on the magnetic tape by the DAT is such that A and B track patterns are alternately and closely adjacent to each other, as shown in FIG. Subcode areas SUB1, SUB2 and ATF signals ATF1, AF2 are recorded in the subcode area and PCM signal area, respectively, in the part and the fixed period immediately before the end. Audio data is recorded in a predetermined signal format.

By the way, there are at least two types of PCM audio data, a sampling frequency of 48 kHz standard mode and a sampling frequency of 32 kHz long time mode (or also called half speed mode).
There is. Half speed mode is 2 modes,
A mode in which the rotation speed of the rotating drum and the tape running speed are ½ times those of the standard mode to enable double time recording of the standard mode, and the rotating speed of the rotating drum and the tape running speed are standard during recording. A mode in which recording can be performed twice as long as that in the standard mode by reproducing the magnetic tape running speed that is equal to the rotation speed of the rotary head in the standard mode at 1/2 times that of the standard mode during reproduction. , There is a mode using so-called double scanning.

A DAT that performs signal recording / reproduction for a long time using this double scanning is known, and during reproduction in double scanning, the rotary head scans at a rate of four times for adjacent A and B tracks.

When reproducing the signal recorded by scanning the rotary heads 1a and 1b, a track convenient for detecting the ATF signal is the A track reproduced by the first scan by the rotary head 1a and the track 1 reproduced by the rotary head 1b. The B track reproduced by the first scanning is used, and ATF2 on the end side of the A track reproduced by the first scanning by the rotary head 1a and the start end of the B track reproduced by the first scanning by the rotary head 1b. AT based on signals obtained by sampling ATF1 and
It has a configuration for generating an F signal.

(Problems to be solved by the invention) However, in the above-mentioned conventional DAT, even if the pseudo lock state where the tracking error becomes stable during the reproduction in the double scanning, the means for releasing the lock state is provided. Or the S / N of the reproduced sound deteriorates,
There is a problem that a state in which no reproduced sound is produced may last for a long time.

That is, when the tracking error does not occur, the rotary head 1A in the ATF2 of the A track at the time of the first scanning by the rotary head 1a is on the phase advance side (as shown in FIG. 2, the rotary head 1a is in the traveling direction of the magnetic tape T). The second sample and hold circuit 13A, which will be described later, outputs a sample and hold signal having a "-" polarity. Immediately after this, the rotary head 1b in the ATF1 of the B track of the first scan by the rotary head 1b is displaced toward the phase delay side (the rotary head 1b is in the direction opposite to the running direction of the magnetic tape T), and as a result, it will be described later. The third sample hold circuit 13B outputs a sample hold signal of "+" polarity. The second and third sample and hold circuits 12, 13B
The levels of the sample and hold signals are substantially the same, and the ATF signal is output based on the levels.

Then, when a tracking error occurs,
The rotary head 1a is displaced in the direction opposite to the running direction of the magnetic tape T (because the phase is delayed), the ratio of the B track adjacent to the right side of the A track is increased, and the ATF2 on the trailing side of the A track The signal level obtained by sampling is smaller than that in the normal state, and complementarily to this, the rotary head 1b shifts in the same direction as the running direction of the magnetic tape T (the phase advances), and the rotary head In 1b, the ratio of the above B track adjacent to the A track increases,
The signal level obtained by sampling ATF1 on the starting end side of the B track is higher than that under normal conditions, and the ATF signal output based on this is compared with the ATF signal in the state where no tracking error occurs. , ATF1 (ATF2) is the same, except that the signal obtained by sampling has the opposite phase. As a result, the scanning of the rotary heads 1a and 1b becomes stable in the state where the tracking error continues (pseudo lock state), and the ATF signal in the state where the tracking error does not occur despite the tracking error state is generated. It will continue to be output.

Therefore, the above-mentioned conventional DAT cannot release the pseudo lock state, so that there is a possibility that the S / N of the reproduction signal based on the PCM audio data may be deteriorated or that the reproduction sound may not be output for a long time. There was a problem.

(Means for Solving Problems) In order to solve the above problems, the present invention provides a rotary head type digital signal recording / reproducing apparatus having the following configuration.

In the first mode, the PCM audio data obtained by pulse-code modulating the audio signal and the multiplex signal having the tracking detection signal before and after the PCM audio data for a predetermined period sequentially form tracks on the magnetic tape by the rotary head. When the data is recorded or the amount of data per unit time is 1/2 times that of the first mode, and the rotation speed of the rotary head and the running speed of the magnetic tape are in the first mode. 1
A rotary head type digital signal recording / reproducing apparatus for reproducing a signal recorded in a second mode, which is / 2 times, wherein a magnetic tape traveling speed is set when reproducing a signal recorded in the second mode. The rotational speed of the rotary head is the same as that of the second mode, the rotational speed of the rotary head is the same as that of the first mode, and the rotary head makes four rotations for every two adjacent tracks of the magnetic tape. A first sample-hold circuit for sampling and holding a reproduction signal obtained by scanning the rotary head with a first sampling signal output at a predetermined timing; and an output signal of the first sample-hold circuit from the reproduction signal. A subtraction circuit for performing subtraction, a second sample-hold circuit for sampling and holding an output signal of the subtraction circuit with a second sampling signal, and an output of the subtraction circuit A third sample-and-hold circuit for sampling and holding a signal with a third sampling signal; a first adder circuit for adding output signals of the second and third sample-and-hold circuits; A comparison circuit that compares the output signals of the third sample-hold circuit and outputs a kick signal when the output signal of the third sample-hold circuit is greater than the output signal of the second sample-hold circuit; A second adder circuit for adding the output signal of the adder circuit 1 and the kick signal to output a tracking detection signal; and an ATF signal on the trailing side of one track reproduced by the first scanning of the rotary head. At the timing of detecting the first sampling signal and the second sampling signal delayed for a predetermined time and outputting the second sampling signal.
Of the start side of the other track reproduced by the second scan
A sampling signal generating circuit that outputs the first sampling signal and the third sampling signal delayed by a predetermined time at a timing of detecting an ATF signal, and a cap that transfers a magnetic tape based on the tracking detection signal. A rotary head type digital signal recording / reproducing apparatus having a structure for controlling a rotational phase of a stun.

(Embodiment) FIG. 1 is a block diagram showing a first embodiment of the present invention, FIG. 2 is an explanatory view for explaining a reproduction state using double scanning, and FIGS. 3 (A) to 3 (F). FIG. 3 is a timing chart for explaining the operation of the block configuration shown in FIG.

As shown in FIG. 1, a rotary head 1a and another rotary head 1b, which faces the rotary head 1a, are fixedly attached to the rotary surface of the rotary drum 1. The magnetic tape T is obliquely wound around the rotary drum 1 over an angle range of 90 °.
It is pinched by the capstan 2 and the pinch roller 3 and runs in the direction of the arrow.

The rotary heads 1a and 1b have gaps whose azimuth angles are opposite to each other, are wider than the tracks (for example, 1.5 times), and are rotated integrally with the rotary drum 1. The rotary shaft 4a of the drum motor 4 is fixed to the central portion of the rotary drum 1.

Next, the recording / reproducing operation in the double scanning of this rotary head type digital signal recording / reproducing apparatus will be described.

Revolving heads 1a and 1b that have the same rotational speed as the standard playback mode
The RF signal obtained from the above is amplified by the reproduction amplifier 6 and then supplied to the reproduction system (not shown) and also to the ATF block 25.

The reproduction signal supplied to the ATF block 25 is the ATF block 25.
Is supplied to an equalizer (EQ) 7 that composes the filter and an envelope detection circuit 9 through a low pass filter (LPF) 8.
Is supplied to.

The reproduction signal supplied to the equalizer 7 is supplied to the ATF signal detection circuit (SYNC detection circuit) 11, which is a sampling signal generation circuit, via the comparator 10, and after the ATF signal is detected here, as shown in FIG. Sampling pulse SP1 (first sampling signal), sampling pulse SP2A (second sampling signal), sampling pulse SP2B (third sampling signal) (FIG. 3 (D)-
(Illustrated in (F)) is output. The sampling pulse SP1 is supplied to the first sample hold circuit (S / H1) 12,
The sampling pulse SP2A is supplied to the second sample hold circuit (S / H2A) 13A, and the sampling pulse SP2B is supplied to the third sample hold circuit (S / H2B) 13B.

3A is a waveform showing the rotation cycle of the rotary drum 1, FIG. 3B is a waveform showing the timing when the rotary heads 1a and 1b scan the A and B tracks, and FIG. 3C is a pilot signal f1.
Is a reproduced waveform of.

As shown in FIG. 3, the sampling pulse SP1 samples the ATF2 on the trailing end side of the A track reproduced by the first scanning by the rotary head 1a, and also the rotary head 1b.
Of the beginning side of the B track reproduced by the first scanning by
It is output at the timing of sampling ATF1.

The sampling pulse SP2A is output at the timing of sampling the ATF2 on the trailing end side of the A track reproduced in the first scan by the rotary head 1a, and the sampling pulse SP2B is output in the first scan by the rotary head 1b. It is output at the timing of sampling ATF1 on the starting end side of the reproduced B track. Sampling pulse SP
2A and SP2B are output with a predetermined delay after the sampling pulse SP1 is generated.

The low-pass filtered signal by the low-pass filter 8 is supplied to the envelope detection circuit 9, where it is envelope-detected and then supplied to the sample hold circuit 12 and the + input terminal of the subtracter 15A. The detection signal applied to the sample hold circuit 12 is sampled and held here at the timing of the sampling pulse SP1 and then supplied to the-input terminal of the subtractor 15A.

The subtractor 15A outputs a subtraction signal obtained by subtracting the level of the signal sampled and held by the sample and hold circuit 12 from the level of the detection signal supplied from the envelope detection circuit 9. This subtraction signal is supplied to the sample hold circuit 13A and the sample hold circuit 13B. The sample-hold circuit 13A samples and holds the subtraction signal at the timing of the sampling SP2A, and then supplies the output to one + input terminal of the adder 25 and the + input terminal of the comparator 28. The sample hold circuit 13B samples and holds the subtraction signal at the timing of the sampling pulse SP2B, and then supplies the output to the other + input terminal of the first adder 25 and the-input terminal of the comparator 28. Adder
25 is an ATF signal (tracking detection signal) via a device 26 after adding signals from the sample hold circuits 13A and 13B.
Is output, and this signal is supplied to one input terminal of the second adder 27.

The comparator 28 detects the magnitude of the signal level of the 2-sine pull pulse obtained from the sample hold circuits 13A and 13B, and supplies the detection result to the other input terminal of the adder 27.

When the tracking error does not occur, as described above, the second sample hold circuit 13A outputs the "-" polarity sample hold signal, and the third sample hold circuit 13B outputs the "+" polarity sample hold signal. Then, since the levels of the sample and hold signals are substantially the same, the output of the comparator 28 becomes "L" level. At this time, the rotary head 1a scans the A track in the same direction as the running direction of the magnetic tape T (direction in which the phase advances),
Further, complementarily to this, the rotary head 1b is tracking-controlled so as to scan the B track in the direction opposite to the running direction of the magnetic tape T (direction in which the phase is delayed).

When a tracking error occurs, the output signal of the sample hold circuit 13B becomes larger than the output signal of the sample hold circuit 13A, so the output of the comparator 28 is "H".
It becomes a level. At this time, the rotary head 1a is attached to the magnetic tape T.
The track A is scanned in the direction opposite to the running direction (direction in which the phase is delayed), and complementarily to this, the rotary head 1b moves in the same direction as the running direction of the magnetic tape T (direction in which the phase advances) B.
The tracking is controlled so that the track is scanned.

As a result, when a tracking error occurs, the other + input terminal 2 “H” level kick signal of the adder 27 is applied from the comparator 28. The adder 27 adds the signal obtained by adding the signals of the sample and hold circuits 13A and 13B supplied from the amplifier 26 and this kick signal to the AT.
Output as F signal.

The level of the ATF signal generated in the pseudo lock state at the time of tracking error is higher than that in the normal state.

The ATF signal output from the adder 27 is supplied to the PB input terminal of the changeover switch 14 and the movable contact 14 connected to this contact.
It is applied to one + input terminal of the adder 15 via a, and is added to the output voltage from the frequency-voltage conversion circuit (F-V) 16 applied to the other + input terminal here. Adder 15B
The added voltage from is supplied to the capstan motor drive circuit 17, amplified here, and then supplied to the capstan motor 18 to control the rotation phase of the capstan 3 for transferring the magnetic tape T, and The rotary head 1a is adjusted so that the tracking error is removed by adjusting the phase of the tape T.
Scans the A track in the same direction as the running direction of the magnetic tape T (direction in which the phase advances), and complementarily to this, the rotary head 1b moves in the opposite direction to the running direction of the magnetic tape T (direction in which the phase lags). ), The capstan servo for forcibly controlling the rotation phase of the capstan 2 and adjusting the transfer of the magnetic tape t is performed so that the B track is scanned.

The drum motor 4 that rotates the rotary drum 1 at a predetermined speed is connected to the drum servo circuit 22.

The drum servo circuit 22 is connected to a sensor 23 provided in the vicinity of the rotary drum 1, and a frequency signal corresponding to the rotation speed of the rotary drum 1 is supplied from the sensor 23 and a reference signal is externally supplied. Then, the drum servo circuit 22 performs a drum servo for controlling the rotation speed of the drum motor 4 so that the phase difference between the reference signal and the signal supplied from the sensor 23 is eliminated.

Further, a frequency generator (FG) 19 is provided close to the capstan motor 18, and the frequency generator 19 outputs a frequency signal according to the rotation of the capstan 3. This frequency signal is supplied to the frequency dividing circuit (1 / n) 20, where 1
/ N, then frequency generator 16 and frequency divider circuit (1
/ M) 21 is supplied.

The frequency generator 16 outputs a voltage according to the frequency signal supplied from the frequency dividing circuit 20, and this voltage is applied to the other + input terminal of the adder 15B.

In this way, when the tracking error state disappears, the kick signal is not output from the output of the comparator, so that the ATF signal from the adder 27 returns to the normal signal level, so that the information recorded on the magnetic tape T is reproduced. The ATF signal obtained by the above is added to the voltage generated according to the rotation of the capstan 3 for running the magnetic tape T, and the addition signal output from the adder B15 is used to move the capstan motor 18 to a predetermined position. The normal capstan servo that rotates at speed is performed.

The movable contact 14a of the selector switch 14 to which the ATF signal is applied during recording is PB
Switch from the terminal to the REC terminal. As a result, the reference signal and the frequency dividing circuit (1
/ M) 21 is supplied with the frequency-divided signal and outputs a phase difference signal corresponding to the phase difference between the two signals.

The phase comparator (PC) 24 outputs a phase difference signal to one + terminal of the adder 15B via the REC terminal of the changeover switch 14 and the movable contact 14a, and outputs it. This phase difference signal is applied by the adder 15B to the other + terminal of the frequency-voltage conversion circuit (FV) 16
After being added to the voltage generated in response to the rotation of the capstan 2 from the
The magnetic tape T is supplied to the motor 17, amplified here, and then supplied to the capstan motor 18 to control the rotation speed of the capstan 2 so that the magnetic tape T runs in synchronization with the reference signal.

In this way, the capstan servo that constantly rotates the capstan motor 18 at a predetermined transfer speed is performed.

The drum servo circuit 22 controls the number of rotations of the drum motor 4 so that the rotation of the rotary drum 1 eliminates the phase difference between the frequency signal supplied from the sensor 23 and the reference signal in the drum servo circuit 22. Drum servo is performed to maintain the rotation of the rotary drum 1 at a predetermined level.

Although not described in detail here, in the case of the pseudo lock described above, the output of the adjacent track picked up as crosstalk is larger than the output of the pilot signal f1 of the home track (track to be scanned). A talk signal can be detected and an ATF signal can be generated to unlock the pseudo lock.

(Effects of the Invention) As described above, the rotary head type digital signal recording / reproducing apparatus according to the present invention cancels this state even if a pseudo lock state in which a tracking error continues to occur during reproduction in double scanning. Since it is possible to immediately avoid the tracking error condition, always,
It is possible to output a reproduced sound having a good S / N, and it is possible to eliminate the possibility that a state in which the reproduced sound is not output continues for a long time.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention, FIG. 2 is an explanatory view for explaining a reproduction state in double scanning, and FIGS. 3 (A) to 3 (F) are shown in FIG. 6 is a timing chart for explaining the operation of the block configuration. It is a figure which shows a part. 1a, 1b ... Rotary head, 11 ... Sampling signal generation circuit (SYNC detection circuit) 12A, 13A, 13B ... First to third sample hold circuit, 15A ... Subtraction circuit, 18 ... Capstan motor, 15, 27 ... 1, second adder circuit, 28 ... comparison circuit, A, B ... track, ATF1, ATF2 ... first and second tracking signals, SP1, SP2A, SP2B ... first to third sampling signals, T ... magnetic tape.

Claims (1)

[Scope of utility model registration request] 1. A PCM audio data obtained by pulse-code modulating an audio signal and a multiple signal having a tracking detection signal before and after the PCM audio data for a predetermined period form a track on a magnetic tape sequentially by a rotary head. Data is recorded in the first mode, or the amount of data per unit time is 1/2 times that in the first mode, and the rotational speed of the rotary head and the running speed of the magnetic tape are the first. A rotary head type digital signal recording / reproducing apparatus for reproducing a signal recorded in a second mode which is 1/2 times as large as that in the mode, wherein the signal recorded in the second mode is reproduced. The running speed of the magnetic tape is set to be the same as that in the second mode, the rotating speed of the rotary head is set to be the same as that in the first mode, and the two adjacent magnetic tapes are moved by the rotary head. A first sample-hold circuit for sample-holding a reproduction signal obtained by scanning the rotary head at a rate of four times per rack with a first sampling signal output at a predetermined timing; A subtraction circuit for subtracting the output signal of the sample and hold circuit, a second sample and hold circuit for sampling and holding the output signal of the subtraction circuit with a second sampling signal, and an output signal of the subtraction circuit for a third sampling signal A third sample-hold circuit for sample-holding, a first adder circuit for adding output signals of the second and third sample-hold circuits, and a second sample-hold circuit for the second and third sample-hold circuits The output signals are compared, and the output signal of the third sample and hold circuit is compared with the output signal of the second sample and hold circuit. A comparing circuit that outputs a kick signal when the value is larger, a second adding circuit that adds the output signal of the first adding circuit and the kick signal to output a tracking detection signal, and 1 of the rotary head. The first sampling signal and the second sampling signal delayed by a predetermined time are output at the timing of detecting the ATF signal on the terminal end side of one track reproduced by the second scanning, and the second sampling signal of the rotary head is output.
Of the start side of the other track reproduced by the second scan
A sampling signal generating circuit that outputs the first sampling signal and the third sampling signal delayed by a predetermined time at a timing of detecting an ATF signal, and a cap that transfers a magnetic tape based on the tracking detection signal. A rotary head type digital signal recording / reproducing apparatus having a structure for controlling a rotational phase of a stun.