JPH02312051A - Rotary head system pcm recording and reproducing device - Google Patents

Abstract

PURPOSE:To promote the data read accuracy by changing the delay time of a monostable multivibrator circuit in accordance with a variation of a rotary cylinder in r.p.m. in order to correct its reproducing position on a magnetic tape to be approximately constant. CONSTITUTION:The magnetic tape 1 is controlled in its traveling speed by a magnetic tape driving means 13 in accordance with a target value of a travel ing speed of a mode to be outputted from a controller 12. Then, a revolving speed of the cylinder 3 is detected by an FG generating circuit 8 and a revolving speed detecting circuit 9, and is controlled by a cylinder control circuit 10 to be a speed corresponding to a target value of the revolving speed from the controller 12. Similarly, a rotary phase of the cylinder 3 is detected by a PG generator 5, the monostable multivibrator 6 and a rotary phase detecting circuit 7, and is controlled by the circuit 10 to be a phase corresponding to a target value of the rotary phase from the controller 12. By this method, a timing signal error can be minute, and the controllability of the cylinder can be en sured.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application In recent years, rotary head type recording and reproducing devices such as video tape recorders (VTRs) and digital audio tape recorders (DATs) have been improved in functionality and run magnetic tapes at high speeds. A search function that reads information recorded on magnetic tape while moving the screen, and fast-forward playback are both demonstrated.

The present invention relates to a control system for a rotary cylinder during search control of a rotary head type PCM recording/reproducing apparatus which uses a rotary head to reproduce information on tracks formed diagonally on a magnetic tape such as a VTR or DAT.

2. Description of the Related Art An example of the above-mentioned conventional rotary head type PcM recording and reproducing apparatus will be described with reference to the drawings.

FIG. 5 shows the configuration of a conventional rotary head type PGM recording/reproducing apparatus. 1 is a magnetic tape. 21L
, 2b is a head. 3 is a cylinder, and two heads are attached symmetrically to the rotation axis. Reference numeral 13 denotes a magnetic tape drive means for stably driving the magnetic tape 1 at a variable speed. Reference numeral 8 denotes an FG generator, which generates and detects a frequency signal proportional to the rotational speed of the cylinder 3 together with the rotational speed detection means 9. 6 is a pc generator and 2
The cylinder rotational position (phase) signal is extracted by a magnet or the like attached to a rotational position several degrees before the rotational position of the 1L head. 6 is a monomulti, and by adjusting the pulse width generated by this circuit, 21
It is possible to accurately define the phase of the L head during reproduction. 7 is a cylinder rotational position detection circuit. A cylinder control circuit 1o controls the rotation speed and phase of the cylinder 3. 11 is a cylinder motor drive circuit. 12 is a magnetic tape drive means 13 according to the running mode.
This is a controller that provides a target value for the running speed of the magnetic tape 10 to the cylinder control circuit 10 and a target value for the rotational speed of the cylinder 3 to the cylinder control circuit 10.

The operation of the rotating head type PCM recording and reproducing apparatus configured as described above will be explained below.

In FIG. 6, the magnetic tape drive means 13 controls the running speed of the magnetic tape 1 in accordance with the target value of the running speed of the mode output from the controller 12. In FIG. Also, the rotational speed of the cylinder 3 is determined by the FC of 8 and the rotational speed detection circuit 9.
detected by.

The cylinder control circuit 10 controls the rotational speed of the controller 12 to a speed corresponding to a target value.

Similarly, the cylinder 30 rotation phase is 60PG, monomulti 6
and is detected by the rotational phase detection circuit 7, and controlled by the cylinder control circuit 1o to a phase corresponding to the target value of the rotational phase of the controller 12.

By the way, the relative speed V between the magnetic tape 1 and heads 2&, 2b
□ is expressed by the following formula.

V) IR= (Vat, CO8a-N-Vt)2+ (
V, DSINθ) 2N = Magnetic tape running speed value at the time of search V, ,: Cylinder rotation speed θ at N times speed Nistil angle vt: Magnetic tape running speed at the time of recording The relative speed deviates from that at the time of recording, the playback output signal If the data rate of the magnetic tape is out of the lock range of the reproduction PLL circuit, it becomes impossible to read the recorded information on the magnetic tape. Therefore, when searching, the frequency of the reproduced output signal should be made equal to the frequency at the time of recording.

The rotation speed of the cylinder 3 is set by the controller 12 so as to keep the relative speed between the magnetic tape 1 and the heads 21L and 2b constant.

FIG. 8 shows the traveling locus of the head during high-speed search. As can be seen from the figure, each head runs across multiple tracks, including reverse tracks. The data required during high-speed search is data in the 5UB1.5UB2 area, and data in the extra area will inevitably be output as noise. Data reliability is improved by extracting only the 5UB2 area as valid data. This timing pulse is generated from the cylinder rotational phase signal detected by the rotational position detection circuit 7 by delaying the 60PG signal by a monomultiply for a certain period of time.

Problem to be Solved by the Invention However, in the above configuration, the delay time due to the monomulti 6 is constant, so if the rotational speed of the cylinder changes during high-speed search such as during FF or RKW, the rotational position detection circuit The rotational phase signal output from 7 generates an error.

FIG. 6 shows how this error occurs. Figure 6 (&)
is during normal playback. What is an envelope?Head 21L
, 2b. head switch (
H2N) is a head switching signal that is generated from a cylinder phase signal and serves as a reference for various timing pulses. The entry point is the correct switching position of H2N. During playback, adjustments are made so that there is no deviation as shown in the diagram.

T0 is the time it takes for the cylinder to make 1/2 revolution.

T1 is the amount of time shift in the position of the PG multiplied signal head. T
2 is a mono-multi delay pulse, and 1 is equal to T1 during normal reproduction. T3 is a delay time for switching H2N by delaying by a predetermined phase angle.

That is, the reproduction position on the magnetic tape by the heads 21L and 2b and the phase accuracy of H2N are influenced by the timing of the falling edge of the monomulti delay pulse.

) in FIG. 6 is at FF. TOf is 1/2 cylinder
The rotation time is shorter than T0 because the cylinder rotation speed is faster.

Tlf is the time shift amount of the position of the PG multiplied signal head, T3f
is the delay time of H2N, which is decreasing at a similar rate.

τ2f is a monomulti delay pulse, and the pulse width is fixed, so it is equal to 2. Therefore, the switching timing of H2N is equal to the difference between Tlf and τ2f, that is, ΔT
An error of f occurs.

It is slower than the correct switching position of H2N at 8 points.

Naturally, the reproduction position on the magnetic tape by the heads 2tL and 2b is delayed by ΔTf.

FIG. 6(0) is at RKW. Tor has 1 cylinder
/2 rotation time, which is longer than To because the cylinder rotation speed is slow.

Tlr is the time shift amount of the position of the pc multiplied signal head, T3r
is the delay time of H2N, which is increasing at a similar rate.

τ2r is a mono-multi delay pulse.

Since the pulse width is fixed, it is equal to T1. But?
Therefore, the switching timing of H2N is earlier than the correct switching position of H2N at point C due to the difference between Tlr and T2r, that is, an error of ΔTr. Also, of course, head 2
The reproduction position on the magnetic tape by 1L and 2b is advanced by ΔTr.

In order to reduce this time error, the length of T1 must be shortened. That is, it is necessary to attach the head mounted on the cylinder and the PG generator with strict precision. However, even if the accuracy of normal installation is strict, the limit for cylinder assembly is an angular error of about ±5 degrees, and it is extremely difficult to achieve the desired accuracy of 0.6 degrees to 2 degrees during high-speed searches. Other alternatives to mechanical precision improvements were expected.

In view of the above-mentioned problems, the present invention has been developed so that even when the cylinder rotation speed changes during a high-speed search, the playback position on the magnetic tape by the heads 2a and 2b can be adjusted without relying on mechanical accuracy.
The aim is to minimize errors in timing signals such as the above, ensure cylinder controllability, and improve data reading accuracy.

Means for Solving the Problems In order to solve the above problems, the rotating head type PGM recording/reproducing apparatus of the present invention includes a head, a rotating cylinder on which the head is mounted, and a magnetic tape drive that runs the magnetic tape at a variable speed. means, a phase signal detection means for defining the head position of the rotary cylinder, and a monomulti circuit for generating a delay pulse for correcting and matching the signal from the phase detection means with the recording/reproducing position on the magnetic tape. The apparatus is equipped with a configuration in which the delay time of the monomulti circuit is changed in accordance with the amount of change in the rotational speed of the rotary cylinder so as to correct the reproduction position on the magnetic tape to a substantially constant value.

Effect of the Invention With the above-described configuration, the present invention allows the width of the mono-multi time delay pulse to be varied under control from the controller even when the cylinder rotation speed changes during high-speed search, and the playback position on the magnetic tape by the heads 2L and 2bVc. YaH2N
It is possible to reduce the error in the timing signal to a minute value below a certain value, ensure cylinder controllability, and improve data reading accuracy.

Embodiment Hereinafter, a rotating head type PCM recording and reproducing apparatus according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a rotating head type PCM according to one embodiment of the present invention.
This shows the configuration of a recording/reproducing device.

In FIG. 1, 1 is a magnetic tape. 2a.

2b is a head. 3 is a cylinder, and two heads are attached symmetrically to the rotation axis. Reference numeral 13 denotes a magnetic tape drive means for stably driving the magnetic tape 1 at a variable speed. Reference numeral 8 denotes an FG generator, which, together with the rotational speed detection means 9, generates and detects a frequency signal proportional to the rotational speed of the cylinder 30. 6 is PG generator and 21
The rotational position (phase) of the cylinder is determined by a magnet installed at a rotational position several degrees before the rotational position of the head.
This is to detect. Reference numeral 6 is a monomulti, and by adjusting the pulse width generated by this circuit, the phase during reproduction of the head 2a1 can be accurately defined. 7
is a cylinder rotational position detection circuit. A cylinder control circuit 1o controls the rotation speed and phase of the cylinder 3. 11 is a cylinder motor drive circuit. 1
A controller 2 provides a target value for the running speed of the magnetic tape 1 to the magnetic tape drive means 13 according to the running mode, and also provides a target value for the rotational speed of the cylinder 3 to the cylinder control circuit 1o. Reference numeral 14 denotes a pulse width control circuit which changes the pulse width of the monomulti in response to changes in the rotational speed of the cylinder in response to a signal from the controller 12.

Regarding the rotating head type PGM recording and reproducing apparatus configured as above, the following will be explained using FIGS. 1, 2, and 3.
Let's explain its operation.

In FIG. 1, the magnetic tape driving means 13 controls the running speed of the magnetic tape 1 in accordance with the target value of the running speed of the mode output from the controller 12. Also, the rotation speed of the cylinder 30 is determined by the FG of 8 and the rotation speed detection circuit 9.
The rotational speed of the controller 12 is controlled by the cylinder control circuit 1o to a speed corresponding to the target value of the rotational speed of the controller 12. Similarly, the rotational phase of the cylinder 3 is detected by the PG 5, the monomulti 6, and the rotational phase detection circuit 7, and is controlled by the cylinder control circuit 10 to a phase corresponding to the target value of the rotational phase of the controller 120.

In addition, during high-speed search, the frequency of the playback output signal is set to be equal to the frequency at the time of recording in order to prevent the data rate of the playback output signal from going out of the lock range of the playback PLL circuit due to deviation of the pair speed from the time of recording. , magnetic tape 1 and head 2a.

The rotational speed of the cylinder 3 is set by the controller 12 so as to keep the relative speed of the cylinder 2b constant.

FIG. 8 shows the traveling locus of the head during high-speed search. As shown in the figure, each head runs across multiple tracks including reverse tracks. FIG. 7 shows a schematic diagram of a typical R-DAT track format. As you can see from this figure, the data required for high-speed search is 5UB1,5
The data in the area of UB2 is necessary, and since the data in the extra area will inevitably be output as noise, the data in the area of 5UB1 is
, 5UB2 as valid data, the reliability of the data is improved. This timing pulse delays 60PG for a certain period of time by a pulse created by the monomulti 6 controlled by the pulse width control circuit 14,
This is generated from the cylinder rotational phase signal detected by the rotational position detection circuit 7.

FIG. 2 shows a corrected timing chart of the cylinder rotational phase signal according to the present invention. FIG. 2 (IL) is during normal playback. The envelope is a reproduction output signal from the heads 2a and 2b. A head switch (abbreviated as H2N) is a head switching signal that is generated from a cylinder phase signal and serves as a reference for various timing pulses. Mermaid is the correct switching position for H2N. It has been adjusted so that there is no shift during playback as shown in the diagram. T.

is the time it takes for the cylinder to make 1/2 revolution. T1 is the amount of time shift in the position of the PG multiplied signal head.

T2 is a monomulti delay pulse, which is adjusted to be equal to T1 during normal reproduction. T3 is a delay time for switching H2N by delaying by a predetermined phase angle.

FIG. 2(b) shows the state at FF. Tar has a cylinder of 1/
The time required for two rotations is shorter than To because the cylinder rotation speed is faster.

Tlf is the time shift amount of the position of the PG multiplied signal head, Tar
" is the delay time of H2N, which is shortened at the same rate. τ2f is a monomulti delay pulse, and the pulse width is shortened by the ratio of TO and TOf under control from the controller, changing from T2 to T2f'. However, is equal to Tlf. Therefore, there is almost no error in the switching timing of H2N, and H2N also almost coincides with the correct switching position point B, and of course the playback position on the magnetic tape by heads 2 & 2b is also almost the same. The location is accurate.

FIG. 2 (0) is the time of REW. Tor has 1 cylinder
/2 rotation time, which is longer than To because the cylinder rotation speed is slow.

τ1r is the time shift amount of the position of the PG multiplied signal head, T3r
is the delay time of H2N, which is longer by a similar proportion.

It has become. T2r is a mono-multi delay pulse, and the pulse width is T by the control from the controller.

It is stretched at the rate of and TOr, and changes from T2 to 2r,
is approximately equal to τ1r. Therefore, there is almost no error in the switching timing of H2N, and H2N almost coincides with the correct switching position, point B. Naturally, heads 2a and 2
The playback position on the magnetic tape indicated by b is also approximately accurate.

FIG. 3 shows an embodiment of the pulse width control circuit of the present invention.

1, 2.3 are analog switches.

6 is a mono-multiple cylinder phase control circuit.

4 is a pulse width control circuit that operates upon receiving instructions from the controller. R1, R2, R3, and C are time constant circuits that determine the width of the delay pulse of the monomulti circuit. In this circuit, the time constant is set to the ratio shown in the following equation.

R1:R2:H3N;T2f:T2:T2r(==TO
f:τo:Tor) (T2f, T2.T2r, TOf, To, TOr are the second
This is the time width shown in the figure. ) Turn on analog switch 1 during high-speed search in the FF direction.
When analog switch 2 is turned on during playback and analog switch 3 is turned on during high-speed search in the RICW direction, monomulti delay pulses are generated according to the rotation speed of each cylinder, ensuring accurate cylinder phase control. This is done at the correct timing, H2N also almost coincides with the correct switching position, and naturally the reproduction position on the magnetic tape by the heads 2a and 2b also becomes an almost accurate position.

FIG. 4 shows another embodiment of the pulse width control circuit of the present invention. Reference numerals 1, 2, and 3 are analog switches, and 6 is a mono-multi switch for the cylinder phase control circuit.

4 is a pulse width control circuit that operates upon receiving instructions from the controller. R, 01, (32, C10 is a time constant circuit that determines the width of the delayed pulse of the monomulti circuit. In this circuit, the time constant is set to the ratio shown in the following equation.

cl:C2:C3'=, T2f:T2:T2r(=τo
f:To:Tor) (T2f, T2.T2r, TOf, To, TOr is the second
This is the time width shown in the figure. ) 1 analog switch is OW during high-speed search in the FF direction.
When analog switches L and 2 are turned on during playback, and analog switch 3 is turned on during high-speed search in the RKW direction, monomulti delay pulses are generated according to the rotation speed of each cylinder, ensuring accurate cylinder phase control. The switching is performed at the correct timing, the HEW also almost coincides with the correct switching position, and naturally the reproduction position on the magnetic tape by the heads 21L and 2b also becomes an almost accurate position.

In addition, in the embodiment, the time constant was switched in three stages, but even if it is two or four stages or more, the effect is only the difference in the accuracy of the time timing of phase control due to changes in the cylinder rotation speed, and it depends on the configuration. The effect is the same.

In addition, in the example, the time constant was switched using an analog switch, but if a continuously variable method using an impedance conversion element was used, it would be possible to follow continuous changes in the rotational speed of the cylinder and control the phase. The accuracy of the time timing is further improved, but the basic configuration is the same and the same effect can be obtained.

Further, although the control signal corresponding to the cylinder rotation speed given to the pulse width control circuit is created in the controller 12, it may be created in the cylinder control circuit 1° or another circuit.

Effects of the Invention As described above, the present invention comprises a head, a rotating cylinder on which the head is mounted, a magnetic tape driving means for running a magnetic tape at a variable speed, and a phase signal detecting means for defining the head position of the rotating cylinder. , a mono-multi circuit for generating a delay pulse for correcting and matching the recording/reproducing position on the magnetic tape with the signal from the phase detecting means, and detects the magnetic tape according to the amount of change in the rotational speed of the rotary cylinder. By adopting a configuration in which the delay time of the mono multi-circuit is changed so as to correct the above playback position to a substantially constant value, even if the cylinder rotation speed changes during high-speed search, the cylinder speed due to the delay time of the mono multi-circuit can be changed. The amount of phase error in phase control does not become excessive, the head and PG generator do not need to be mounted with high precision, and errors in the playback position on the magnetic tape by the head and timing signals such as H2N can be corrected. It is possible to make it minute, ensure cylinder controllability, and improve data reading accuracy.

[Brief explanation of the drawing]

FIG. 1 shows a rotary head type PGM in an embodiment of the present invention.
Block configuration diagram of the recording/reproducing device, FIG. 2 (IL),
(b) and (0) are the time of playback of Fig. 1 and FF, HEW
A timing chart showing the operation during high-speed service, Figures 3 and 4 are circuit diagrams showing the configuration of the monomulti circuit in Figure 1, and Figure 5 is a block diagram of a conventional rotary head type POM recording/reproducing device. , FIG. 6 (IL) t (b). (0) is a timing chart showing the operation during playback, FF, and RKW high-speed search in Figure 6, Figure 7 is a schematic front view of the R-DAT track format, and Figure 8 is a magnetic tape during high-speed search. FIG. 3 is a schematic front view showing the trajectory of the head with respect to the upper track. 1...Magnetic tape, 21L, 2b...
Head, 3...Cylinder, 4...Cylinder motor, 6...PG generator, 6...
・Mono multi circuit, 7...Rotational position detection circuit,
8...FG generator, 9...Rotation speed detection means, 1o...Cylinder control circuit, 11
......Cylinder motor drive circuit, 12...
- Controller, 13... Magnetic tape drive means, 14... Pulse width control circuit. Name of agent Patent attorney Shigetaka Awano and 1 other person = Kumi Mushi No. 2 Figure H3N - Figure 3 Figure 4 u++ -++ -++ ---J Figure 6 Figure 7 Figure 8

Claims (1)

[Claims] A device for recording and reproducing information on tracks formed diagonally on a tape-shaped recording medium (hereinafter referred to as magnetic tape), which includes a head, a rotating cylinder equipped with the head, and a magnet that runs the magnetic tape at a variable speed. a tape drive means, a phase signal detection means for defining the head position of the rotary cylinder, and a monomulti circuit for generating a delay pulse for correcting and matching the signal from the phase detection means with the recording/reproducing position on the magnetic tape. A rotary head type PCM recording characterized in that the delay time of the monomulti circuit is changed in accordance with the amount of change in the rotational speed of the rotary cylinder so as to correct the playback position on the magnetic tape to a substantially constant value. playback device.