JPH0463443B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field This invention provides information signals such as audio signals.
Regarding how to play back what was recorded as PCM,
In particular, it relates to a variable speed playback method.

Background Art and Problems When recording and reproducing information signals such as audio signals, high-quality recording and reproducing can be achieved by converting the audio signals into PCM.

Possible methods for recording and reproducing such PCM signals include using a fixed head and recording by sequentially forming diagonal tracks on a tape using a rotating head. When a rotating head is used, the PCM signal is recorded by sequentially forming tracks diagonal to the longitudinal direction of the tape, rather than one continuous track as in the fixed head method. PCM signals can be easily compressed on the time axis and recorded without wasting tape. By compressing the time axis, it is possible to create a period in which the rotary head does not come into contact with the tape, and a device that uses this period in which the rotating head does not come into contact with the tape can be used to process signals using hardware. realizable.

FIGS. 1 to 4 are diagrams for explaining the apparatus and an example thereof.

This uses a plurality of rotating heads. For example, in the case of two rotating heads, a rotating head device as shown in FIG. 1 is used.

The rotating magnetic heads 1A and 1B are equiangularly spaced, i.e.
They are arranged with an angular spacing of 180°. On the other hand, the magnetic tape 2 is wound around the circumferential surface of the tape guide drum 3 over an angular range, for example, 90°, which is narrower than the 180° angular range. The rotary heads 1A and 1B are rotated at a rate of 30 revolutions per second in the direction of arrow 5H, and the tape 2 is run at a predetermined speed in the direction of arrow 5T. 2, diagonal magnetic tracks 4A and 4B are formed, for example, in a so-called overlapping state, as shown in FIG.
The signal is made to be recorded. In this case, the width directions of the gaps of the heads 1A and 1B are set in different directions with respect to the direction orthogonal to the scanning direction. In other words, the so-called azimuth angles are made different.

According to the above rotary head device, there is a period (in this example, a period corresponding to an angular range of 90°) during which the two rotary heads 1A and 1B do not come into contact with the tape 2. The apparatus can be simplified by adding redundant data during recording and performing correction processing during reproduction.

Next, a recording and reproducing system using this rotary head device will be explained.

FIG. 3 shows an example of the recording system.

This example is for recording an audio signal.

In FIG. 3, audio signal S _A is supplied to A/D converter 12 via input signal 11. In FIG.

The A/D converter 12 samples the signal at a sampling frequency of, for example, 44.1kHz, and the sampled signal is, for example,
Converted to 16-bit PCM signal. FIG. 5A shows the output signal S _O of this A/D converter 12.

The output S _O of this A/D converter 12 is supplied to a recording encoder 13 . This recording encoder 1
3 has two memory circuits, for example RAM14,1
5 and a parity word and CRC code addition circuit 16 are connected. In this recording encoder 13, the two RAMs 14 and 15 are activated for 1/60 seconds (head 1A,
The signal S _O is switched every 1/60 second period (corresponding to the time of 1B and a half rotation), and the two RAMs are switched every 1/60 second period.
14 and 15 as shown in FIG. 5B and C. In other words, a data word is written to the RAM 14 during the high level period T _B in the first half of one cycle of the signal RSW, and during the second half period when the signal RSW is at the low level.
At T _A , a data word is written to RAM 15.

Then, the data written to the RAM 14 in the period T _B will be stored in the next time T _A and in the period T _A.
The data written to _RAM15 will be parity words P, Q and
A CRC code is added and read.

That is, the 60Hz signal CP (Fig. 5E) from the control signal generation circuit 17 is transmitted to the PIT and CRC.
The code is supplied to the additional circuit 16 for generating the code, and
This signal CP in the first half of T _A and T _B periods P _AP and P _BP
becomes _high level, the generation/addition circuit 16 is activated, and the first half of the period P _AP
Then, for the data written in the RAM 14, parity words P, Q and CRC codes are formed for the data written in the RAM 15 in the first half of the period P _BP of the period T _B. Added RAM14 and 15
will be written again. And each period T _A
In the latter half of periods P _AR and P _BR of P and T _B , the data to which the parity words P, Q and CRC code are added is read out at approximately twice the writing speed.

In this case, the data every 1/60 second is divided into blocks of 1470 data words in units of 6 data words, as shown on the right side of Figure 5A, and 1470÷6=245
The blocks B ₀ , B ₁ , B ₂ . . . B ₂₄₄ . In addition to these six data words _W0 to _W5 , this one block also includes parity words P, Q, and CRC.
A code is added and a block synchronization signal is added.
It is configured by adding SYNCB and block address signal ADC. In addition, 6 blocks are considered to be 1 block.
The data words are interleaved within the range of data for a unit period of 1/60 seconds to strengthen against burst errors. Furthermore, a preamble signal used to generate a clock for data extraction during reproduction of the unit time data, and a postamble signal indicating the end of the unit time data are added.

In this way, data for each unit period obtained from the recording encoder 13 is supplied via the amplifier 18 to the two rotary heads 1A and 1B.

In this case, heads 1A and 1B are connected to the reference 30Hz pulse CT from the control signal generation circuit 17.
A phase servo is applied to synchronize with the period
In P _AR , head 1A scans tape 2 exactly,
During the period _PBR , the head 1B is just scanning the tape 2. That is, the pulse CT is supplied to the servo circuit 20, while the heads 1A,
A 30 Hz pulse PG from a pulse generator 21 that generates one pulse per rotation of the 1B is supplied to this servo circuit 20, and its output is supplied to a head driving drum motor 22 for phase servoing. .

Therefore, the data read out from the RAK 14 for a unit time is recorded by the head 1A forming one track 4A on the tape, and is stored in the RAM.
The unit time worth of data read from the tape 15 is recorded by the head 1B forming one track 4B on the tape.

Note that the pulse CT from the control signal generation circuit 17 is sent to the magnetic head 2 through the recording amplifier 23.
4, and a track 6 for control pulses during playback is provided at the edge of the tape 2 as shown in
Recorded as C.

The audio signal recorded as a PCM signal is reproduced as follows.

That is, in the reproduction system shown in Fig. 4, head 2
4, a 30Hz pulse CTL is reproduced from track 6C of tape 2, this pulse CTL is supplied to the control signal generation circuit 17, and the signal from this control signal generation circuit 17 is reproduced as the pulse CTL.
and a constant phase relationship. Then, the reference 30 from this control signal generation circuit 17
The Hz signal CT is supplied to the servo circuit 20, and the pulse PG from the pulse generator 21 is supplied to the servo circuit 20, so that the heads 1A and 1B rotate with a constant phase relationship with respect to the signal CT. Servo controlled. Although not shown, the signal CT from the control signal generation circuit 17 and the reproduction control pulse CTL are compared in phase,
The comparison output controls the capstan drive motor to control the transport speed of the tape 2, thereby ensuring that the heads 1A, 1B are correctly aligned with the tracks 4A, 4.
Tracking control is performed to scan B. Therefore, reproduced signals are obtained from heads 1A and 1B as shown in FIGS. 5F and 5G.

Further, pulses from the head 24 are supplied to a control signal generating circuit 17.

The reproduction outputs of the heads 1A and 1B are supplied to a switch circuit 32 through amplifiers 31A and 31B, respectively, and this switch circuit 32 receives the 30Hz signal from the control signal generation circuit 17 and the signal SH.
(FIG. 5H), the signal is alternately switched to one input terminal and the other input terminal, thereby obtaining a signal in which the reproduced outputs of the heads 1A and 1B are alternately obtained. The output of this switch circuit 32 is supplied to a digital signal restoration circuit 33 and restored to a digital signal, which is then supplied to a decoder 34 to restore the original signal.
Restored to PCM signal S ₀ .

That is, in the decoder 34, the two RAMs 35 and 36 are switched in periods T _C and T _D of 1/60 seconds by the control signal RSW _P (K in FIG. 5) from the control signal generation circuit 17. , 5th
As shown in Figures I and J, the playback output for one track from the head 1A is written to the RAM 35 during the first 1/120 second period of the period T _C , and during the first 1/120 second period of the period _TD . One track's worth of playback output from head 1B is written to RAM 36. And 1 written in these RAM35, 36
Track data is for periods T _C and T _D , respectively.
Error correction is performed during the 1/120th period in the latter half of the period. That is, during this latter half period of 1/120 seconds, the control signal WC (L in FIG. 5) from the control signal generation circuit 17 supplied to the correction circuit 37 is at a high level, and the correction circuit 37 is enabled to operate. Parity P, Q and CRC codes are used to correct errors within their correction capabilities.

In this way, RAM35 and 36 are written,
The error-corrected reproduced data for each track is transferred to the next period T _D as shown in Figures I and J.
and T _C are read out alternately at half the writing speed. In other words, PCM signals expanded on the original time axis are obtained continuously.

Note that this decoder 34 decodes the data word arrangement to return it to the original state of the PCM signal _S0 .
Interleaving is also performed.

The PCM signal from the decoder 34 is corrected in the error correction circuit 38 for data that could not be processed by the correction circuit 37, and the D/A converter 3
9 and is converted back into an analog audio signal. This is the one that is led out to the output terminal 41 via the amplifier 40.

However, the rotary head type apparatus as described above has the following drawbacks when performing variable speed playback in which the speed of the tape during playback is made faster or slower than the speed during recording. That is, for example, if the tape speed is doubled from that during recording, the playback speed will be doubled, but at this time, the inclination angle θ of the scanning locus of the head on the tape with respect to the longitudinal direction of the tape will be The inclination angle θ ₀ with respect to the longitudinal direction of the tape becomes different, and the rotary head cannot correctly scan the recording track, but instead scans over a plurality of tracks. To prevent this, the rotational speed of the head can be increased by a multiple of the tape speed. In other words, if the speed is double, the number of rotations of the head should also be doubled.

However, in that case, the signal transmission rate is also 2
Since the signal processing speed is doubled, the signal processing speed also needs to be doubled, which has the drawback of requiring a very high-speed signal processing device.

Therefore, generally, the rotational speed of the rotary head is kept constant, and the reproduced signal is corrected by interpolation processing or the like to perform variable speed reproduction.

In the case of video signals, even if signals from a plurality of tracks are connected, since the signals of the plurality of tracks have a vertical correlation, a certain degree of reproduced image can be obtained on the screen. However, in the case of audio signals, there is no such correlation at all, so there is a risk that the reproduced sound will be unlistenable.

Furthermore, even if the inclination angle θ of the head scanning locus is corrected by some method during playback to match the inclination angle θ ₀ of the recording track, the widthwise extension direction of the gap of the rotary head is limited due to high-density recording. In the case of devices using a plurality of different rotating heads, the following disadvantages arise. In other words, when using two heads, for example, if the tape speed is increased by an even number, say twice, the number of rotations of the rotary head does not change.
As shown by the arrows in the figure, the scanning positions of the heads are two-track pitch, and when one head is aligned to correctly scan the corresponding recording track, the other head will scan not the corresponding track but a different track. This causes the inconvenience that during the scanning period of the other head, no reproduced signal can be obtained due to serious loss.

Purpose of the Invention This invention uses the above-mentioned rotating head to
It is an object of the present invention to provide a method for reproducing a PCM signal, in particular, to enable variable speed reproduction to be performed satisfactorily without signal deterioration.

SUMMARY OF THE INVENTION In the present invention, the speed of the rotary head is kept constant and does not change from the normal speed even during variable speed playback, and the tape feeding method is devised.

That is, when the rotating head contacts the tape and scans the recording track to extract the playback signal, the tape is fed at normal speed, and during other periods the tape speed is set to a speed different from the normal speed, and the rotating head contacts the tape again. When extracting the playback signal, control it so that it is at normal speed,
When averaged, the desired normal speed N (N=
n/m, where m and n are integers).

In this way, when the rotary head scans the tape and obtains a reproduction signal, the tape is fed at normal speed, so that the rotary head scans the recording track with the correct inclination angle.

Furthermore, even when using multiple rotary heads with different widthwise extension directions of the gap, the tape is fed at normal speed until all of these multiple rotary heads come into contact with the tape, and then these heads are fed at normal speed. The tape is fed at a speed different from the normal speed until it comes into contact with the tape and the playback signal is taken out, and the tape is fed to a position where each rotary head scans the corresponding track at the next scanning position. If this is done, the tape feed speed is normal during the period when the head is in contact with the tape and a playback signal is obtained, so there is no error in the relationship between the rotating head and the recording track, and a good playback signal can be obtained. It is something that can be done.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings, taking as an example a case in which it is applied to the apparatus shown in FIGS. 1 to 5 above.

The example shown in the figure is an example of a playback device having a normal playback mode and a double speed playback mode.

Figure 7 shows an example of the tape running system.
The figure is a time chart for explaining the double speed playback mode.

In FIG. 7, reference numeral 3 denotes a tape guide drum, and rotary heads 1A and 1B are attached so as to face outward and slightly protrude from the gap between the upper drum and the lower drum of this guide drum 3, and the servo circuit 20 The drum is rotated on the circumferential surface of the drum at a constant rotational speed by a motor 7 which is servo-controlled. In this example, the servo circuit 20 is supplied with a frequency signal FD _D from a frequency generator 8 coaxially provided with the motor 7 as a speed information signal, and pulses are supplied as a rotational phase information signal of the rotary heads 1A and 1B. A pulse signal PG from a generator 21 is supplied. Furthermore, a reference signal CT of 30 Hz from the control signal generation circuit 17 is supplied. Then, the output of the servo circuit 20 is supplied to the motor 7, and the rotation of the motor 7 is controlled so that both the rotational frequency and phase are locked to the reference signal CT of 30 Hz. As shown in the figure, the tape 2 is wound obliquely over a 90° corner range of the circumferential surface of the drum 3.

Further, 51 and 52 are a capstan and a pinch roller, and the capstan 51 is rotated by a capstan motor 53. Then, the pinch roller 52 is pressed against the capstan 51, and the capstan 51 is rotated by the motor 53, so that the pinch roller 52 and the capstan 5
The tape 2 held between the tapes 1 and 1 is transported, for example, in the direction of the arrow in the figure.

60 is a capstan servo circuit, and this capstan servo circuit 60 includes a capstan motor 53.
The output FG _C of the frequency generator 54 attached to the control signal fixed head 24 is supplied, and the pulses regenerated by the control signal fixed head 24 are supplied to the flip-flop circuit 55 and shaped into a rectangular wave signal CTL, which is unnecessary as described later. The signal is supplied to the servo circuit 60 via a mask circuit 56 that masks the control signal. Well, rotating head 1A,1
The signal PG indicating the rotational phase of B is sent to this servo circuit 6.
0.

In this servo circuit 60, a frequency signal corresponding to the speed of the motor 53 from the frequency generator 54 is used.
FG _C passes through the amplifier 61 to the frequency voltage converter 62
The voltage is supplied to the comparator circuit 63 to generate a voltage according to the frequency. A reference voltage from a speed reference generation circuit 64 is supplied to this comparison circuit 63. This speed reference generation circuit 64 is supplied with a mode select signal _MSL through an input terminal 65, and also receives pulses from the pulse generator 21.
PG is supplied. In the normal reproduction mode, a constant reference voltage is supplied from the generating circuit 64 to the comparator circuit 63, and the output of the comparator circuit 63 is supplied to the capstan motor 53 through the combining circuit 66 and error amplifier 67. tape 2
is transported at a constant speed. In this normal playback mode, the playback control signal CTL is not masked at all from the mask circuit 56 and is obtained as a 30Hz signal, which is supplied to the phase comparison circuit 68 and the pulse generator 21 The pulse PG from the comparator 63 is supplied, the phases of the two are compared, and this error voltage is supplied to the combining circuit 66 and added to the speed servo signal from the comparator 63. The output of the phase comparison circuit 68 controls the scanning positions of the heads 1A and 1B on the tape 2 so as to correctly scan the recording tracks 4A and 4B. The audio PCM signal is then reproduced as described above.

Next, the case of double speed playback mode will be explained.

At this time, a signal having a predetermined relationship with the signal CT is obtained as a speed reference signal by the mode select signal _MSL from the input terminal 65, and this is supplied to the comparator circuit 63, and the output of the comparator circuit 63 2 is transferred as follows.

In this case, if the point at which the head 1A starts contacting the tape 2 is the beginning phase (0°) of one rotation period, the rotary heads 1A and 1B rotate at a constant speed regardless of the tape speed, so as shown in FIG. As shown by hatching at B, the head 1A abuts the tape 2 during a rotational phase period A from 0° to 90°, and the head 1B abuts the tape 2 during a rotational phase period B from 180° to 270°.

On the other hand, from 0° during each rotation period RT ₁ , RT ₂ ...
During the period up to 270°, the tape 2 is transported at a normal speed, and from 270° to 360° (then one rotation period,
During the period up to 0°), the tape 2 is transported at high speed to a position skipping one track by each of the heads 1A and 1B.

Therefore, heads 1A and 1B scan tape 2 as follows.

FIG. 8A is a diagram for explaining the recording track pattern on _the tape ₂ and the scanning _state of the rotary head. 4
Recording tracks 4B ₁ , 4B ₂ , 4B ₃ recorded by head 1B between A ₁ , 4A ₂ , 4A ₃ ...
...and exist alternately.

In Fig. 8, the first rotation period RT ₁ 0°~
During the 270° period, the tape 2 is being transported at the normal speed, so if the above-mentioned tracking servo is working, the head 1A correctly scans the track _4A1 during the contact period A, and the head 1B
correctly scans track _4B1 during contact period B.

Then, during this one rotation period RT ₁ , the head 1A, 1
The tape 2 is fed at high speed during the period from 270° to 360° in which the heads B do not contact the tape 2 together, and in the next rotation period RT ₂ , the head 1A skips the track 4A ₂ during its contact period A. Track 4A ₃ , head 1B skips track 4B ₂ and tracks 4B ₃ ,
Each of them is scanned.

In the following order, heads 1A and 1B have one rotation period.
In RT ₃ , tracks 4A ₅ and 4B ₅ , in the next one rotation period RT ₄ , tracks 4A ₇ and 4B ₇ , and then in the next one
During rotation period RT ₅ , tracks 4A ₉ and 4B ₉ ...
Scan each. Therefore, the amount of information in the reproduced signal is halved.

Drive voltage of capstan motor 53 in this case
_EDR is shown in Figure 8C. 270°~360° of this voltage E _DR
The duration and level of high voltage supply during this
Between 270° and 360°, heads 1A and 1B each scan the next track position skipped by one track, and the tape speed returns to normal speed at 0° of the next rotation period. Something like that is done. Assuming that the tape speed changes instantaneously, applying a high voltage that is five times the normal speed over the entire period 270° to 360° will yield an average tape speed that is twice the normal speed. It will be done. However, in reality, the feeding speed of the tape 2 does not respond instantaneously, so the high voltage period is not the entire period from 270° to 360°, as shown in Figure 8C, and moreover, its value is 5. The speed is set to be more than double the speed. Therefore, as shown in FIG. 8D, the tape 2 gradually increases from the normal tape speed during the period of 270° to 360°, and when it reaches a predetermined value, gradually decreases to a low speed, and then continues for the next one rotation period. in
At the point of 0°, the state returns to normal tape speed. Then, the high speed tape feeding speed during this 90° rotation angle period of 270° to 360° and the normal tape speed during the other periods are selected so that the average is exactly twice the speed.

At this time, as shown in FIG. 8E, one control signal recorded at the end of the tape in the width direction is always reproduced during the high-speed feeding period. Since the tape speed when correctly tracking the rotary heads 1A and 1B to the recording track is the normal playback speed, the control signal CTR should be 30Hz, and the presence of the signal CTL obtained during this high-speed feeding will disrupt the tracking. . Therefore, the above-mentioned mask circuit 56 removes this extra pulse portion of the signal CTL.

This mask circuit 56 can use, for example, a retrigger type monostable multivibrator. That is, this retrigger type monostable multivibrator is triggered by the fall of the reproduction control pulse CTL (FIG. 8E) from the flip-flop circuit 55. The time constant of this monostable multivibrator is longer than the time from the falling point of the pulse CTL to the falling point of the playback control pulse obtained when directly feeding the tape at high speed, for example, the time constant is equivalent to 1/2 period of the 30 Hz signal. The period is assumed to be τ. Therefore, this monostable multivibrator is always re-triggered by the falling edge of the playback control pulse obtained during high-speed tape feeding, and its output signal is the playback controller pulse during high-speed tape feeding, as shown in Figure 8F. A masked 30Hz signal is obtained.

Therefore, the tracking servo is activated correctly, and the heads 1A and 1B correctly scan the corresponding tracks during each rotation period RT ₁ , RT ₂ , RT ₃ .

The signal processing in this case is exactly the same as the signal processing in the normal reproduction described above, and the modes of the RAMs 35 and 36 are as shown in FIG. 8F and G. However, in this case, in the example of Fig. 8, the tracks 4A ₂ , 4B ₂ , whose suffixes are even numbers,
Since no reproduction signal can be obtained from 4A ₄ , 4B ₄ ..., the reproduction output is from track 4 as shown in Figure 8H.
The reproduced signal S ₁ from A ₁ , the reproduced signal S ₂ from track 4B ₁ , the reproduced signal S ₅ from track 4A ₃ , the reproduced signal S ₆ from track 4B ₃ , and the following sequentially reproduced signals are S ₉ , S ₁₀ , S ₁₃ , S ₁₅ , S ₁₇ , S ₁₈ . . . will continue discontinuously every two tracks.

Such discontinuous signals S ₂ and S ₅ , S ₆ and S ₉ , S ₁₀
At the joint between S 13 and S ₁₃ , pulse noise may be generated because the waveform is not continuous as shown in FIG. 8I. This can be prevented by performing the following processing. That is, the 8th
As shown in Figure J, at the junction of signals where the waveform is discontinuous, the level difference between the signals before and after the junction is detected, and the level difference is taken as the P-P value.The waveform shown in Figure 8J is obtained. The alternating current component of is added to the joint. If this is done, the waveform will not jump in level at this joint, so no pulse noise will occur.

The process for this seam is not limited to the above method, and various other methods can be used.

The above is a case of 2x speed playback, but the present invention is not limited to this, and can be used not only for high speed playback such as 3x speed playback and 4x speed playback, but also for 1/2x speed playback and 1/3x speed playback. It can also be applied to low-speed playback.

Figure 9 shows a time chart for triple speed playback, in which heads 1A and 1B come into contact with tape 2 as shown in Figure 9B during one rotation period.
In the periods 0° to 90° and 180° to 270°, tape 2 is fed at normal speed, and in the periods 90° to 180° and 270° to 360°, when heads 1A and 1B do not contact tape 2, the speed is as described above. The tape 2 is transported two track pitches at high speed in the same manner as in the double speed case. The driving voltage of the capstan motor at this time is shown in FIG. 9C.

Therefore, as shown in FIG. 9A, head 1
After A scans track _4A1 , head 1B scans track _4B2 , then head 1A scans track _4A4 , then head 1B scans track _4B5 , and so on. Scanning is performed every two tracks. In this case, six track pitches are sent during one rotation period, and two of these tracks are played back, resulting in triple speed playback.

The reproduced output signals at this time are audio signals of 1/60 seconds each as S ₁ , S ₄ , S ₇ ,
S ₁₀ ..., it will be obtained intermittently. In this case as well, since the waveform is discontinuous at the joints of signals of 1/60 seconds, the above-mentioned joint processing is performed to prevent the generation of pulse noise.

Note that this triple-speed playback can also be achieved by increasing the amount of high-speed tape feeding to four tracks in the example of FIG.

In short, to perform n-times speed playback (n is an integer greater than or equal to 2), tape 2 is fed by 2n tracks during one rotation period, and one of the tracks is fed to heads 1A and 1B, for a total of 2 tracks. During each contact period of one rotation period, when the tape feed speed is normal speed, the rotary head 1
It is sufficient if A and 1B are scanned.

Next, FIG. 10 shows a time chart for 1/2 speed playback.

In this case, in principle, the tape 2 is fed at normal speed during one rotation period R _M every other rotation,
In the remaining rotation period of every other rotation RT _S , tape 2
is stopped. However, in practice tape 2
Since there is inertia in the transport of the tape 2, after the contact period of the head 1B in the period R _M is over, the feeding speed of the tape 2 is made extremely low, and the tape is fed one track pitch to the 0° phase point of the next period R _M. At the 0° phase point, the tape speed returns to normal speed.

The driving voltage of the capstan motor at that time is shown in FIG. 10C, and the change in tape speed is shown in FIG. 10D, respectively.

In this way, the heads 1A and 1B correctly scan the tracks 4A and 4B with the same inclination angle during the period _RTM every other revolution. During this period _RTM , the reproduced signals from the heads 1A and 1B are demodulated by the decoder 34.
In _RTS , the reproduced signals from heads 1A and 1B are discarded. In other words, heads 1A and 1B
The reproduction signal output is taken out every one rotation period.

Therefore, as shown in FIG. 10A and B,
Heads 1A and 1B are all consecutive tracks 4
A ₁ , 4B ₁ , 4A ₂ , 4B _{2 .} Therefore, the playback time is doubled,
Can be played at 1/2 speed.

In this case _, there will be no signal during the period RT _S in which no signal is extracted, but as shown in _{FIG .} , . . . are read out twice each time, it is possible to obtain temporally continuous reproduction signals. In this case, the same signal S ₁ and
Since the waveforms are often discontinuous at the joints between the signals S ₁ , S ₂ and S ₂ , the above-mentioned joint processing is performed on the discontinuous joints.

In this way, in order to perform 1/m double speed playback (m is an integer of 2 or more), the tape is fed at normal speed during one rotation period out of m rotation periods, and the tape is moved to head 1A,
It is sufficient to take out the playback signal from head 1B, and during the remaining m-1 rotation period, the tape is almost stopped and no playback output is taken out from heads 1A and 1B.

Note that this invention has two rotary heads as described above.
It is easy to understand that it can be applied not only to the case of 1 piece but also to the case of 1 piece or 2 or more pieces.

Effects of the Invention In this invention, as described above, when the rotary head scans the tape and extracts the playback signal, the tape is fed at the normal speed, so that the angle between the scanning locus of the head and the longitudinal direction of the tape is It is equal to the tilt angle of the recording track. Therefore, since the head scans the recording track correctly, the same signal as in normal reproduction with a good S/N ratio can be obtained as a reproduction signal.

Moreover, in the case of high-speed playback, the tape can be fed at high speed by utilizing the period when the head does not contact the tape, so that the processing of the playback signal can be greatly simplified.

Furthermore, this invention not only improves the method of feeding the tape without changing the rotational speed of the rotary head.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of a rotary head device used in an example of an apparatus to which the method of the present invention is applied, FIG. 2 is a diagram showing its recording track pattern, and FIG.
The figure is a block diagram of an example of a recording system of an apparatus to which the method of this invention is applied, FIG. Chart, FIG. 6 is a diagram for explaining the purpose of this invention, FIG. 7 is a diagram showing an example of a device for realizing the method of this invention, and FIG.
Figures 1 to 10 are time charts for explaining the method of this invention. 1A and 1B are rotating heads, 2 is a tape, 3 is a tape guide drum, 51 is a capstan, 53 is a capstan drive motor, and 60 is a capstan servo circuit.

Claims (1)

[Claims] 1 A device for reproducing PCM signals recorded as diagonal recording tracks on a recording medium using a rotating head, the period during which the rotating head is in contact with the recording medium and during which the reproduced signal is extracted from the recording medium. During the period, the recording medium is transported at a normal speed, and during other periods, the tape is transported at a speed different from the normal speed, and when averaged, the tape speed is N times the normal speed (N=nm;
m and n are integers greater than or equal to 1)
How to play PCM signals.