JPS61294657A - Magnetic tape reproducing device - Google Patents

Abstract

PURPOSE:To perform speedy high-speed reproduction by using a servo-control signal consisting of the difference between a reference voltage signal and a voltage signal generated by detecting the envelope of the playback signal of a tape which is outputted from each head, and converting the detection signal into a voltage. CONSTITUTION:The playback signal of the tape is applied with enveloped detection by an envelope detecting circuit 9, and the frequency of the detection signal of the detecting circuit 9 is converted by a converting circuit 10 into a voltage to generate a voltage signal proportional to the running speed of the tape. The servo-control signal is generated on the basis of the difference between the output voltage signal and the reference voltage signal of a reference signal output circuit 15 and a reel motor is driven with the servo signal to perform servo-control over the running speed of the tape. Consequently, the running of the tape in fast reproduction is brought under the servo-control of the simple, inexpensive constitution regardless of the kind of the tape, thus carrying out the speedy high-speed reproduction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a rotary head helical scan type magnetic tape reproducing apparatus such as a rotary head type digital audio chip recorder or an 8 mm video table recorder.

[Conventional technology]

Conventionally, rotary head digital audio tape recorders (hereinafter referred to as R-DAT) and 8mm video tape recorders (hereinafter referred to as 8mm VTR) are magnetic tapes on which azimuthally recorded tracks are formed diagonally in the running direction. and two rotary heads with different azimuth angles, and the tape is generally played back by normal playback with the tape running speed set to the standard speed, that is, the same speed as during recording.

During normal playback, the tape runs at a standard speed, so both heads alternately play the tape along each track. At this time, the tape running speed is determined based on the pilot signal for the tracking side recorded on each track. is servo-controlled to the tilting speed to ensure stable playback.

On the other hand, when adding high-speed playback functions such as a high-speed search function to an R-DAT or 8mm VTR, it is necessary to set the standard tape speed higher than the standard speed to perform high-speed playback. For example, on February 26, 1985, Sony Corporation published “Program Number High-Speed After-Recording Invention (PROPO8)”.
AL OF PROGRAMN (JMBERQUIC
As described above, it has been considered to set the tape running speed during high-speed playback to 200 to 300 times the standard speed.

During high-speed playback, the running speed of the tape and the rotational speed of both heads are faster than during normal playback, so both heads alternately play the tape diagonally across several tracks.In this case, the pilot signal The servo control based on this is no longer possible, and at this time the tape running speed is controlled by the rotation of the rolling motor on the supply side and the take-up side.

By the way, the various standards for the recording format of R-DAT are as follows.
A technology study group (DAT CONFERENCEWG-B
) is currently working on determining various standards.

At the technical review committee, each track of the R-DAT tape was divided into 22 blocks of subcode areas (A) and (B), and 11 blocks of ATF areas (C) and (D), as shown in Figure 6. , 130 block PCM area (E)
The pilot signal is divided into 5 areas of ATF area (
C), (D) While recording the VC, the PCM signal of the audio signal is recorded in the PCM area (E) [and the PCM signal of time information, 9 track number information, 2 cue information, and high-speed access reference information is recorded in the subcode area. (A), CB) and PCM area (E).

Moreover, the audio signal and the PCM signal of each information are 1.
176~4-74-7O4(7) P with fundamental wave component
It has been proposed that the signal be formed using a CM signal.

Therefore, when reproducing the recorded audio signal and each information by reproducing the tape, based on the PLL control of the reproduced PCM signal, the
It is necessary to form a reproduced clock of -49-4O8 and to control reproduction and decoding of the PCM signal based on the reproduced clock.

The lock range of the PLL control is set based on the frequency of the PCM signal reproduced during normal reproduction, and if the frequency of the PCM signal reproduced during high-speed reproduction is significantly different from the frequency during normal reproduction, the reproduction clock is The track reading linear velocity, which consists of the velocity component in the direction along each track of the PCM signal, must be controlled to the standard velocity during normal playback.
In AT, it is necessary to servo control the tape running speed to a predetermined constant speed even during high-speed reproduction, and to control the track reading linear speed to a standard speed.

It should be noted that even with an 8 mm VTR, it is necessary to servo control the fixed speed of the tape during high-speed playback to prevent stable playback.

[Problem that the invention seeks to solve]

By the way, as mentioned above, R-DAT and 8mm VTR
In this case, since servo control using pilot signals does not work well during high-speed playback, the running speed of the tape must be servo-controlled by some method that does not use pilot signals during high-speed playback, but R-DAT and 8mm VT
In the R, nothing has been invented that servo-controls the running speed of the tape during high-speed playback.

On the other hand, in the case of conventional audio tape recorders that record and play analog audio signals on magnetic tape, when feeding the tape at high speed during high-speed playback, for example,
As described in Publication No. 9-8155, the rotation period of the reel morph on the tape supply side and the rotation period of the reel motor on the take-up side are measured, and the rotation period is constant at the larger or smaller of the measured re-rotation periods. Weighted with
Further, by controlling the running speed of the tape so that the sum of the weighted rotation period and the unweighted rotation period is always constant, servo control of the tape speed is performed.

Therefore, also in the case of R-DAT and 8 mm VTR, it is possible to apply the method described in the above publication to servo control the tape running speed during high-speed playback, and in this case, measurement of the surface rotation period If such operations are to be performed by a microcomputer, it is conceivable that the tape running control circuit be constructed in blocks as shown in FIG.

To explain the operation shown in Figure @7, the rotation of the tape supply side reel motor (1), 2 take-up side reel motor (2), supply side director (3) consisting of a Hall element, etc., 9 take-up side detector ( 4), and the detection signal of the rain detector (3) m (4) is input to the microcomputer (5) K, and the computer (5) detects the detection signal of the rain detector (3) e (4). Measures the rotation period of both reel motors (1) and (2) based on the count of each signal, digitally performs arithmetic processing such as weighting, and outputs a digital signal for servo control of the reel motor (2). do.

Further, the digital signal for servo control of the reel motor (2) outputted from the computer (5) is converted into analog by an analog converter (6), and is sent from the converter (6) to the reel motor via the drive amplifier (7). (2) An analog drive signal based on the digital signal is supplied.

Then, based on the drive signal, the reel motor (2) is controlled and servo-controlled so that the sum of the weighted rotation period and the unweighted rotation period is always constant, and the track reading linear speed is controlled to the standard speed. becomes possible.

However, in the case of Fig. 7, the reel motor (1), (
Detectors (3) and (4) to detect the rotation period of 2)
It is necessary to provide such things in the mechanism part, and it is also necessary to perform complicated arithmetic processing using the computer (5).
There is a problem that it becomes complicated and expensive.

In addition, the method disclosed in the above publication can only be applied when the maximum winding radius of the tape is known in advance, so it cannot be used when playing many types of magnetic tapes (including cassette tapes) with different lengths and thicknesses. requires preprocessing such as calculating the maximum winding radius of each tape when playing back each tape, and in fact, R-DAT and 8mm VTR
Since it is envisaged that many types of cassette tapes will be played back, it is necessary to carry out the pre-processing described above unless, for example, a cassette half of each cassette tape is equipped with an isdicator with a maximum winding radius. There is a problem that high-speed playback becomes impossible and the process becomes even more complicated.

The present invention provides a magnetic tape playback device using a rotating head helical scan method, such as an R-DAT and an 8mm video tape recorder, without having to perform complex arithmetic processing during high-speed playback. The technical problem is to servo control the running speed of the tape to perform rapid high-speed playback regardless of the type of tape.

[Means for solving problems]

This invention was made with the above points in mind,
A magnetic tape in which each azimuth-recorded track is formed diagonally in the running direction, and a plurality of rotary heads for playing back the tape, and during normal playback when the tape runs at a standard speed, each of the heads is connected to the The tape is sequentially played back along the tracks, and during high-speed playback when the tape runs at a higher speed than the standard speed, the tape is controlled to run by the rotation of the reel motor, and the head moves diagonally across each track. A rotating head helical scan type magnetic tape playback device that sequentially plays back the tape across the tape, comprising: a detection circuit for envelope-detecting playback signals of the tape output from each head during high-speed playback; A frequency/voltage conversion circuit that converts the frequency of the detection signal output from the circuit into a voltage, and a servo control signal output that forms and outputs a servo control signal consisting of the difference between the output voltage signal of the conversion circuit and a reference voltage signal. and a reel motor drive section that drives the reel motor using the servo control signal.

[Effect]

During high-speed playback, each rotary head diagonally crosses each track on the tape, so the tape playback signal output from each head during high-speed playback has fluctuations in amplitude due to azimuth matching and misalignment. The frequency of the waviness changes in proportion to the running speed of the tape.

Therefore, by performing envelope detection on the tape playback signal output from each head, the frequency of the detected signal obtained by the detection changes at a ratio Fl t to the tape running speed, and the detected signal is converted into a voltage. By servo-controlling the reel motor using a servo control signal consisting of the difference between the voltage signal formed by the servo control signal and the reference (pressure signal), the running speed of the tape is servo-controlled to a predetermined speed based on the reference voltage signal.

〔Example〕

Next, the present invention will be explained in detail with reference to FIG. 1 showing one embodiment thereof and FIGS.

Figure 1 shows the case where the R-DAT rc is applied [c] In the figure, (8) is the restocking signal input terminal into which the high frequency reproduction signal of each rotary head is input, (9) is the input terminal (8). αQ is a frequency/voltage conversion circuit connected to the detection circuit (9).

αη is a sample bold circuit connected to the conversion circuit αQTIC, @ is a head switching signal input terminal into which a head switching pulse signal is input, and 0 is a running direction signal whose level varies depending on the fixed direction of the tape. The input terminal α4 is a gate signal output circuit that outputs a gate signal for sample and hold to the sample and hold circuit aυ based on the head switching pulse signal and the running direction signal.

(to) is a reference voltage signal output circuit that selectively outputs two types of reference voltage signals based on the traveling direction signal, and αQ is the inverting input terminal (to) for the output signal of the sample and hold circuit αυ.
The reference voltage signal output from the output circuit αG is input to the non-inverting input terminal (→.aη is the phase compensation circuit connected to the differential amplifier a0,
(to) is a limiter circuit connected to the phase compensation circuit α, which outputs a servo control signal to a reel motor drive unit (not shown) via a servo control signal output terminal 09. (1) is a servo control signal output section having a structure shown by a broken line.

By the way, as shown in Fig. 2, R-DAT is a magnetic tape (rT) which has an even or odd track (ta) recorded at a positive azimuth angle and an odd or even track (tb) recorded at a negative azimuth angle. is formed obliquely in the dorsal direction, and has a rotation head with a positive azimuth angle and a rotation head with a negative azimuth angle.

During normal playback, the tape (T) runs at standard speed,
At this time, the track (ta) is helically scanned by the rotary head with a positive azimuth angle, and the track (tb) is helically scanned by the l1Tl motor≠≠kid head with a negative azimuth angle, and the head trajectories of both heads are the second. As shown by the solid line HXVc in the figure, each track (ta),
(tb) The trajectory follows each.

On the other hand, during high-speed playback, the tape (T') is at the standard speed of 200
The rotational speed of both heads becomes faster than that during normal playback, and in this case, the head trajectory of the side head becomes several tracks (ta) as shown by the solid line Hy in Fig. 2.
It becomes a locus that occupies L (tb) diagonally.

Therefore, during high-speed playback, a rotating head with a positive azimuth angle traces not only the track (ta) but also the track (tb), and at this time, since the azimuth angle of the track (tb) is a negative azimuth angle, the track (tb) During tracing, almost no reproduced signal can be obtained.

Similarly, when @Jden≠≠kihetmo with a negative azimuth angle, during high-speed playback, not only the track (tb) but also the +-rack (t
a), and at this time, during the tracing of the track (ta), the reproduced signal is hardly obtained.

Therefore, during high-speed reproduction, the reproduced signal input to the detection circuit (9) via the input terminal (8) has an amplitude fluctuation as shown in FIG. 3(a). At this time, the envelope line detection signal 1c of the detection circuit (9) outputs the detection signal shown in FIG. 3(b) to the conversion circuit αQ.

Then, the conversion circuit αQ converts the frequency of the input detection signal into a voltage, and generates a voltage signal proportional to the frequency of the waviness,
That is, a voltage signal proportional to the running speed of the tape is output from the sample and hold circuit α])vc ratio.

In addition, the "Real results of R-DAT format (EXPERIMENTAL 5PECIFICATI
As described in ON0FR-DAT FORMAT)J, the frequency of the reproduced signal when reproducing the PCM signal in the PCM area (E) of FIG. 6 is 1M or more.

Further, the frequency of the pilot signal recorded in the ATF areas (C) and (D) in FIG. 6 is set to about 130 KHz.

Since the frequency of the undulation is about several KHz, especially each track (t a ) # (tb )
(F) P Changes only in proportion to each time CMx.

Therefore, by controlling the voltage signal based on the PCM main rear (E) reproduction signal of each track (ta)*(tb) to be constant, the running speed of the tape (T) can be servo controlled.

On the other hand, the running speed vector of the tape (T) during normal playback,
If the rotation speed vectors of both heads p are Vtx and Vhx, then the relative running speed vector of both heads with respect to the tape (T) VC is the running speed vector along track (1) as shown in Figure 1.4. , that is, the traveling speed vector Vo vc of the standard speed.

And the running speed vector of the tape (T) during high-speed playback,
Since the rotational speed vectors Vty and Vhy of the heads are in the same direction as the vectors Vtx and Vhx, by adjusting the magnitude of the vector Vty through servo control as shown in Figure 134, the relative position of both heads to the tape (T) can be adjusted. Truck (1) IF- with running speed vector vy
The component vector in the direction along the line can be set as the traveling speed vector vO, and the head reading linear speed during high-speed playback can be set to the same standard speed as during normal playback.

By the way, if the tape (T) runs at a nearly constant speed during high-speed playback, the timing at which the PCC clear E) of each track (ta) and (tb) is traced is determined by the timing at which the input terminal (to ) for a certain period of time after a predetermined period from the rise and fall of the head switching pulse (No. 3).

And in R-DAT, the tape is attached to the head cylinder at 90°.
The track (t a ) e ( t b
) is traced only during approximately 9o from the rise and fall of the head switching pulse signal, and at this time the input terminal (8
) The input reproduction signal becomes tc as shown in Fig. 5), and the period Z in Fig. 5(b) corresponds to each trough (ta), (t
b) o) PCMx7 (E) Indicates the playback period.

Therefore, the gate signal shown in FIG. 5(C) formed by the output circuit α4Vc based on the head switching pulse signal and the running direction signal is input to the sample and hold circuit αη, and based on the gate signal, the sample and hold circuit αη is The voltage signal of period Z is sampled and held.

In addition, in fast-forward playback and rewind playback, the frequency and P of the detection signal when the head reading linear speed becomes the standard speed.
If the tracing timing of the CM area (E) is different, for example, when playing at high speed 200 times the standard speed, sample 23 cycles of the playback signal using the 1 gate signal during fast forward playback, and then rewind the playback. Since it is sufficient to sample 64 cycles of the reproduced signal using one gate signal, the output circuit α→ varies the output timing of the gate signal based on the traveling direction signal.

Then, the voltage signal output from the sample and hold circuit αυ, that is, the voltage signal of the reproduction signal of the PCM area (E) of each track (ta) and (tb), is input to the inverting input terminal (to) of the differential amplifier αQ. In addition, the output circuit αυ
The reference voltage signal output from the differential amplifier α is inputted to the non-inverting input terminal (+) of the differential amplifier α, and is sent from the differential amplifier Q to the phase compensation circuit aη, and then sent to the output of the conversion circuit αq via the sample-and-hold circuit αυ. A differential signal proportional to the difference between the output voltage signal and the reference voltage signal of the output circuit QG is output.

By the way, in fast-forward playback and rewind playback, when the head reading linear velocity becomes the standard speed, that is, when the component vector of the velocity vector Vty in the direction along track (1) in FIG. 4 becomes the velocity vector vO, the conversion circuit Since the voltage signals output from αQ are different, there are two types of output circuits (to) that are equal to the voltage signals output from conversion circuit a0 when the head reading linear speed of each of fast forward playback and rewind playback reaches the standard speed. It forms a reference voltage signal, and selectively outputs both layer quasi-voltage signals based on the traveling direction signal.

Therefore, the output from the differential amplifier αQ is: F1. The 1-minute signal is a signal proportional to the difference between the detected tape (T) running speed and a predetermined reference speed at which the head reading linear speed becomes the standard speed.

Then, the differential signal output from the differential amplifier α0 is averaged and phase compensated by the phase compensation circuit αη, and the output signal of the phase compensation circuit αη is input to the limiter circuit (to), and from the limiter circuit Q8 to the output terminal. A servo control signal consisting of the difference signal is output to the reel motor drive unit VC via α.

The limiter circuit αQ is provided to prevent an abnormal rise in the level of the servo control signal when there is no reproduction signal, and sets the upper limit level of the servo control signal.

By the way, the reel motor drive section is formed of, for example, the drive amplifier (7) I/C shown in FIG. 7, and drives the take-up side reel motor based on the input servo control signal.

Then, the rotation of the reel motor on the take-up side is servo-controlled by the servo control signal, so that the short sound speed of the tape (T) is set to a predetermined short sound speed at which the head reading linear speed becomes the standard speed during normal playback, i.e. It is servo-controlled to a constant speed based on a reference voltage signal.

Therefore, according to the above embodiment, during high-speed playback such as fast-forward playback and rewind playback, the running speed of the tape (T) changes the head reading linear speed to the standard speed during normal playback based on the envelope detection signal of the playback signal. Servo 1 is sub-controlled to a predetermined running speed, allowing high-speed reproduction of R-DAT.

In addition, there is no need to install a detector etc. in the mechanism section that ejects the rotation of the reel motor, and there is no need to use arithmetic processing for ':Jt miscellaneous data, so there is no need to use an expensive and complicated arithmetic processing device such as a microcomputer. Servo control can be performed with a simple and inexpensive configuration.

Further, since the length, thickness, etc. of the tape (rT) do not affect servo control, various magnetic tapes can be used without preprocessing, and rapid high-speed reproduction can be performed.

Furthermore, the number of periods of the reproduced signal sampled by gate No. 1 is relatively large, and the phase compensation circuit α''7)
Since the difference signal is averaged by VC, the servo control signal does not fluctuate even if, for example, an erroneous conversion occurs in the conversion circuit σQ, and stable servo control can be performed.

Note that in place of the limiter circuit (g) of the embodiment described above, a speed control circuit may be used that outputs the lower level of the output signal of the phase compensation circuit αη and the internally set upper limit level signal.

Further, in the above embodiment, a sample hold circuit αη and an output circuit α4 are provided in order to perform accurate servo control using only the reproduction signal of the PCM area (E) of each track (ta) and (tb). However, both circuits 01) and α→ may be omitted.

Furthermore, it can be applied to high-speed playback of 8mm VTRs, and of course can be applied to various magnetic tape playback devices such as VH8 and β video tape recorders.

〔Effect of the invention〕

As described above, according to the magnetic tape playback device of the present invention, the detection circuit (9) performs envelope detection of the tape playback signal, and the frequency of the detection signal of the detection circuit (9) is converted into a voltage by the conversion circuit αq. By using the servo control signal to drive the reel motor and servo control the tape running speed, the tape can be played back at high speed regardless of the type of tape with a simple and inexpensive configuration. It is possible to perform rapid high-speed playback by controlling the running of the rotary head, especially for rotary head helical head type digital audio recorders and 8mm video tape recorders where servo control signals cannot be obtained during high-speed playback. It has achieved remarkable results when applied to high-speed playback in scan-type magnetic tape playback devices.

[Brief explanation of drawings]

1 to 5 show an embodiment of the magnetic tape playback device of the present invention, FIG. 1 is a block diagram, and FIG. 2 is an explanatory diagram of head traces during normal playback and high-speed playback, @3
Figures (a) and (b) are waveform diagrams of the playback signal and detection signal during high-speed playback, Figure 4 is an explanatory diagram of the tape and head velocity vectors during normal playback and high-speed playback, and Figure 5 (a).
) to (C) are diagrams explaining the operation of Figure @1, and Figure @7 is a block diagram of a servo control section of a conventional tape recorder. (9)...detection circuit, αQ...frequency/! positive conversion circuit, (1)...servo control signal output section, (T)...
-Magnetic tape, (ta), (tb), (t)...track.

Claims (1)

[Claims] (1) A magnetic tape in which each azimuthally recorded track is formed diagonally in the running direction, and a plurality of rotary heads for playing back the tape, and each of the heads during normal playback when the tape runs at a standard speed. plays the tape sequentially along each of the tracks, and during high-speed playback when the tape runs at a higher speed than the standard speed, the tape is controlled to run by the rotation of the reel motor, and the head moves along each of the tracks. In a magnetic tape playback device using a rotating head helical scan method that sequentially plays back the tape diagonally across a track, a detection circuit detects an envelope of a playback signal of the tape output from each head during high-speed playback; , a frequency/voltage conversion circuit that converts the frequency of the detection signal output from the detection circuit into a voltage, and a servo that forms and outputs a servo control signal consisting of a difference between the output voltage signal of the conversion circuit and a reference voltage signal. A magnetic tape playback device comprising: a control signal output section; and a reel motor drive section that drives the reel motor using the servo control signal.