JPS63247946A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To control a high tape speed with high accuracy under a condition where influences of various fluctuation are not exercised, by correcting a reference value in accordance with tape speed detecting information reproduced from a tape and controlling a reel motor. CONSTITUTION:Rotational cycles of a feeding reel 1 and winding reel 2 are respectively detected by means of cycle detectors 3 and 4 and a tape speed is calculated by square multipliers 5 and 6 and an adder 7. The tape speed is compared with a reference value set by an up-down counter 19 in which a preset reference value from a reference value generator 8' is set at a subtractor 9 and the tape speed is controlled to a desired value through a reel motor 10. This reference value is corrected by means of a counter, whose up- counting or down-counting value is controlled in accordance with the deviation between the reference value and a value corresponding to the actual tape speed supplied from a control pulse cycle detector 17 upon receiving the reproduced output of the control pulse recorded on the tape by means of a control head 12. As a result, the high tape speed is controlled with high accuracy irrespectively of the thickness and total length of the tape, uneven winding of the tape, and the variance of diameter of reel hubs.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic recording/reproducing device (hereinafter referred to as a VTR), and in particular controls the rotational speed of a reel motor on the take-up side to record a tape at a predetermined tape running speed. The present invention relates to a tape running control system for running the tape.

Conventional technology There is a method to keep the tape speed constant by sandwiching the tape between a capstan and a pinch roller and keeping the capstan's rotational speed constant. This is extremely difficult due to the mechanism of the drive device, and there is also the possibility of tape damage, so a method is used in which the tape speed is kept constant without a capstan.

A conventional capstanless tape running control system is disclosed in, for example, Japanese Patent Laid-Open No. 102007/1983.

FIG. 9 is a block diagram showing an embodiment of this conventional tape running control system, in which 1 is a supply reel (hereinafter referred to as 51 J-le) with a knob radius of Rh and a reel radius of R8; 2 has a hub radius of Rhs! A take-up reel whose J-le radius is R1 (hereinafter referred to as 'l' IJ-le), 3 an S reel period detector that detects the rotation period of the S reel, 4
is a 'l' IJ-le period detector that detects the rotation period of the T reel, 5 is a first square calculator that receives the S reel rotation period Ts as input, and 6 receives the T IJ-le rotation period Tt as input. 7 is an adder that adds the outputs Ts' and Tt2 of the first and second secondary calculators; 8 is a reference value generator that generates a reference value stone 2; 9 is a reference value. 1o is T IJ-
A reel motor rotates the reel in the direction of the arrow and drives the tape. 11 is a motor control circuit that drives and controls the reel motor o.

Here, Tt=T reel rotation period Ts=S///l Δ=Tape thickness L=Tape total length■ -Tape speed, Ts+Tt-o2 ・・・・・・・・・・・・・・・
・Represented by 0).

In equation (2), Δ, L, and Rh are all constants, and the value of ΔL and Rh2 are constants, so it can be seen that if the left side of equation (1) is held constant, the tape speed V will also be constant. . That is, by measuring the rotation periods Ts and Tt of both reels and controlling the speed of the tape winding motor according to the above equation, the desired tape speed V can be achieved. For example, if Ts+Tt)-., the motor may be controlled to increase the rotational speed of the T reel and speed up correspondence.

FIG. 9 is an example of the method described above, in which the S IJ-le period detector 3 and the T-reel period detector 4 detect both reel periods "S".
#Tt is detected. first and second square calculators 6;
6, "s r Tt is input, Ts' r Tt2
is output to the adder 7. The adder 7 outputs T8+Tt2, and the subtracter 9 uses the reference value generator 8 to drive the reel motor 10 and send an error signal, thereby controlling the tape speed V to be constant.

Problems to be Solved by the Invention However, in the above configuration, the tape thickness Δ and the total tape length 1. Although it is possible to control the tape speed V to a constant value when the IJ-ruhub radius Rh changes (when there are multiple types), there is a problem in that the tape speed V does not match the desired tape speed. . Furthermore, when winding a tape, there are always variations in tape tension and tape winding irregularities such as winding strongly and weakly during the process of starting and stopping tape transport.
) Even if the tape speed was controlled by setting the reference value shown on the right side of the equation, there was a deviation in the desired tape speed.

In general, tape running control in a VTR requires the tape to be transferred at a predetermined tape running speed in order to record and reproduce video and audio signals on the tape. Therefore, even in special playback modes such as fast-forward playback, the tape is transported by capstan drive.

However, when transporting a tape at a high speed such as 50x playback, it is difficult to transport the tape using a capstan and a pinch roller, resulting in the problems described above.

In view of this point, the present invention provides the following advantages even when the tape thickness Δ, the total length of the tape, and the reel hub radius Rh are different.
To provide a VTR capable of high-speed running control at a desired tape speed even if uneven tape winding exists.

Means for Solving the Problems The present invention provides a detection means for detecting information related to the rotation period of the supply reel and the rotation period of the take-up reel, and the information detected by the detection means and the tape to be controlled. A calculation processing means for calculating a reference value set corresponding to the speed, a tape transfer control means for controlling tape transfer based on the output result of the calculation processing means, and a tape transfer control device for controlling tape transfer during tape transfer control. A magnetic recording and reproducing device comprising: a tape speed detecting means for detecting the speed by reproducing a signal already recorded on the tape; and a correcting means for correcting the reference value based on the information detected by the tape speed detecting means. It is.

Effect: With the above-described configuration, the present invention corrects the reference value so as to eliminate deviations between the actual tape speed and the control target speed caused by variations in tape thickness, overall tape length, reel hub diameter, etc., or uneven tape winding. Rudame,
Tape transport is precisely controlled to the desired tape speed.

Embodiment FIG. 1 shows a block diagram of a VTR according to a first embodiment of the present invention, especially for VHS system and β system VT.
A control signal (hereinafter referred to as
This is applied to VTRs on which CTL signals (referred to as CTL signals) are recorded. In FIG. 1, 12 is a CTL head, 13
14 is a regenerative amplifier; 14 is a waveform shaping circuit; 16 is a retriggerable monostable multivibrator (hereinafter referred to as M, M) that is triggered by the rising edge of the output pulse of the waveform shaping circuit; 16 is the output of M, M, 15; A first switch circuit (hereinafter referred to as SW) in which the signal is turned on when the signal is set to HighO, 17 is a reproduction OTL signal period detector, and 18 is a CTL period detector 1.
A comparator 19 compares the reproduced CTL signal period TOTL obtained at 7 and the output T of the reference value generator 8'.A comparator 19 compares the output T of the reference value generator 8' after the reference value 1σ output from the reference value generator 8' is preset. an up/down counter (hereinafter referred to as a U/D counter) whose counter value increases or decreases depending on the output of 18;
o is a cylinder with a built-in rotating magnetic head (not shown);
211L~. is a post that regulates tape travel, and the tape is being transported in the direction of the arrow.

Note that blocks having the same configuration as in FIG. 6 are given the same numbers.

FIG. 2 shows the waveforms of the main parts of FIG. The converted signal, C, is the output signal of 1jM, 16.

The operation of the first embodiment will be explained below based on FIGS. 1 and 2.

In a VH5 system or a β system VTR, a CTL signal is recorded at 5 oz during recording. Therefore, the tape speed can be determined by detecting the cycle of the reproduced CTL signal. for example,
It can be seen that if the reproduction CTL signal period is 1500H2, the tape is being transported at a speed 60 times faster.

In the first embodiment, when the tape is transferred at high speed, tape transfer is controlled in blocks 1 to 11 so that the sum of the squares of both reel cycles is constant, as described in the conventional example. When high-speed tape transport is started, the output value -♂ from the reference value generator 8' is preset in the U/D counter 19. Then, the sum of squares of the U/D counter reel period T, ” + Ti2
The difference C1("s2+Tt) is supplied to the motor control circuit 11, and the reel motor 1o is controlled so that this difference becomes zero. When the tape is being transported at high speed, the CTL head 12 outputs the reproduction CTL signal to the motor control circuit 11. The signal obtained as shown in Fig. 2a is pulsed through the regenerative amplifier 13 and the waveform shaping circuit 14, and then input to the MIM, 16 and the CTL period detector 17.The regenerated CTI signal is detected by CTL period detection. The period TOTL is detected by the device 17 and outputted to the comparator 18. On the other hand, the comparator 18 detects the reference value TN input from the reference value generator 8' and the period signal input from the CTL period detector 17. The TOTL is compared, and if the first 5W16 is ON depending on the size, the counter value of the IT/D counter 19 is counted up or down.In other words, due to variations in tape thickness, uneven winding, etc. If you plan to transfer the tape speed, but the tape is actually being transferred faster than the target speed,
'ratc becomes smaller than TN, and the output of the comparator 18 increases the value C1 of the U/D counter and operates to slow down the rotational speed of the reel motor 10.

Conversely, if the actual tape speed is slow and the transfer control is being performed, the LT/D counter value C1 is decreased and the rotational speed of the reel motor 11 is increased.

The output signal TN of the reference value generator 8' is calculated from the CTL cycle, and when the control target speed is N times the tape speed during recording, TN has a value corresponding to 30 x N (Hz). , is output to the comparator 18.

In this way, the actual tape speed is detected by the reproduction CTL cycle, the reference value for tape speed control is corrected (increased or decreased), and the tape speed is controlled so as to eliminate the deviation from the target speed described in the conventional example.

If a reproduced CTL signal cannot be obtained due to a tape section where no CTL signal is recorded, a dropout, or even tape damage, 'reτL will become very large, and if the actual tape speed is faster than the target speed. However, it is determined that the tape speed is slow, and the value C1 of the U/D counter is decreased, resulting in an operation in which the tape speed is further increased. Therefore, in order to prevent such malfunctions, the first SW1 6 is turned off if the reproduced CTL signal is not detected for a certain period of time. ljM, 15 is triggered by the rising edge of the pulsed reproduction CTL signal and outputs High for a certain time TMM. Therefore, TMM is set to be larger than the period of TCTL (with a margin of 'r
ctt), the playback CTL
If the signal cannot be obtained midway, the output C of M, M, 15 becomes Low and the first SWl 6 turns OFF.0 Therefore, if the first SW1e is 0FFI, the output C1 of the υ/D counter 19 changes. Instead, the value immediately before the first SWl 6 was turned off is maintained, and tape transfer control is performed using this C1 and the sum of squares of both reel cycles Ts+Tj.

As described above, even when a reproduced CTL signal cannot be obtained midway, malfunction of tape speed control can be prevented.

Microcomputer / Managed various calculations for 1 hour in the evening.

It is widely used in electronic equipment because it can easily handle measurement and data input/output control. Therefore, it is possible to construct the first embodiment of the present invention using a microcomputer, and the processing procedure is shown in an example in which the block 39 surrounded by the dashed line in FIG. 1 is constructed using a microcomputer. The operation will be explained based on the flowchart shown in FIG.

When N-times-speed tape high-speed transfer control is started, the reference value -♂ calculated from the above-mentioned equations (1) and (2) is loaded into (C1) of the microcomputer RAM. Then, both reel periods Ts + ”t are read and (C1
) ("s' + Tt)2 and outputs the result of this calculation as error data to the motor control circuit 11. Next, the cycle 'rcth of the pulsed reproduction CTL signal is read and Check whether Tcyt is larger than TMM.If Tcyt, ≧TMM,
Since it is recognized as an unrecorded section, the following process (reference value correction process) is not executed, and the process returns to reading the cycle of both reels. (If Tayh < TMM, the actual tape speed is the target It is checked whether the speed is faster than the specified speed, and the reference value is corrected depending on the state.

TOfL "In the case of a τ blade, the actual tape speed is equal to the target speed, and no processing is performed on the reference value (G1), and the process returns to reading both reel cycles. Tayt, < TN In the case of , the actual tape speed is faster than the target speed, and the reference value (C1) is increased. (In this example, (C1) is increased by +1.)
(If +TL > T, the actual tape speed is slower than the target speed, and the reference value (C1) is decreased. (In this example, (C1) is decreased by -1.)
When the correction of the reference value (C1) is completed, both reel periods are read again and the process returns.

It is also possible to replace block 39 in FIG. 1 with a microcomputer using the processing procedure described above.

In addition, both reel periods Ts * Tt, CTI, period TOT
L can be easily detected by using the well-known timer interrupt processing of a microcomputer.

FIG. 3 is a block diagram showing the main parts of a second embodiment of the present invention, which is particularly applied to an 8 mm VTR, and blocks 12 to 18 in FIG. 1 are the blocks shown in FIG. 3. Replaced.

As is well known, the 8mm VTR format is a system that performs tracking based on a pilot signal reproduced by the rotating head itself.In a system that does not use a conventional control signal in the longitudinal direction of the tape, the first embodiment The method shown cannot be used.

Figure 4 is a diagram showing the recording magnetization locus of an a-mm VTR and the head scanning locus during high-speed tape transport (in this example, 10x speed). The four types of pilot signals are sequentially repeated for each field and superimposed on the TV program signal, and during reproduction, the level of the stroke signal of the pilot signal reproduced from the recording tracks adjacent to the front and back of the track to be reproduced. This is a system that performs tracking using a tracking error signal according to the difference. Therefore, in the second embodiment, attention is paid to one type of frequency (hereinafter described as f'jP) among four types of pilot signals. , f'
The actual tape speed is detected at the playback frequency of +p. In other words, one field is 60H2 in the NTSC system.
In an 8ξIJ VTR in which pilot signals of four different frequencies exist, fjF can be obtained at 1 sHz at the normal reproduction speed.

In FIG. 3, 22L and 22b are rotary magnetic heads built into the cylinder 2°, 231L and 23b are regenerative amplifiers, 24 is a second switch circuit (hereinafter referred to as SW2),
25 is a terminal to which a head switch signal is supplied; 26 is a filter (hereinafter referred to as LPF) for obtaining only a specific frequency flP signal from the television signal reproduced from the rotary heads 22&, 22b'; 27 is r, p 28 is a tuning circuit 27 that can obtain an output signal by tuning only to
29 is a pulse shaping circuit for converting the output of the detection rectifier circuit 28 into pulses, and the above configuration replaces blocks 12 to 14 in FIG. .

In FIG. 4, symbols 1sBl+, . . . indicate respective recording magnetization trajectories on the magnetic tape, arrows 36 indicate the tape transport direction, and arrows 36 indicate the scanning direction of the rotary head. '
1p-f4p indicates a pilot signal for tracking control. That is, the pilot signal f'1p is sent to the truck driver 1.
is recorded. Arrows 37 and 38 indicate head scanning trajectories when the tape transport speed is 10 times the speed. When the tape is transported at a tape speed 10 times the tape speed during recording, the rotary head scans from the start end of track person 1 (lower end on the paper) to the end of track B5. That is, the trajectory shown by the arrow 37 is taken. In a two-head helical scan type VTR, when Muherad is located at the end of track B5, head B is located at the beginning of track B5. Therefore, the B head follows the trajectory indicated by the arrow 38. FIG. 6 shows the waveforms of each main part in FIG. 3.

The operation of the second embodiment configured as described above will be described below.

Head switching signal (d) supplied through terminal 25
In other words, SW2 is the rotating head 22a.

The signals regenerated from the LPF 22b and passed through the regenerative amplifiers 23& and 23b are sequentially switched and supplied to the LPF 26. L
A signal having only the frequency of f'IP is supplied by the PF 26 to the tuning circuit 27, and a signal (15) is obtained.

The detection rectifier circuit 28 processes the signal e into a signal f, which is then pulsed into a signal g in the pulse shaping circuit 29.

Therefore, as explained in the first embodiment, this signal g
The period T11 of is detected by the pilot period detector 17',
The reference value TN at N times the speed is supplied from the terminal 30 to the comparator 18', which compares the periods of T)l and Tf+, and
is ON, the output C1 of the U/D counter is increased or decreased via the terminal 31.

In addition, in the second embodiment, M, M, 15' (Q pulse width T MM' is the same as that of the CTL signal in the first embodiment.
As is clear from the fact that the pilot signal f+P is recorded at 16Hz while it is recorded at 0H2,
It is desirable to set the pulse width to twice the pulse width set in the first embodiment. Furthermore, the reference value T supplied from the terminal 30
N needs to be set to a value corresponding to 15XN (Hz).

As described above, as shown in the second embodiment, even in an 8mm VTR that does not use a control track, the first
Similarly to the embodiment, it is possible to eliminate deviations from the target speed caused by tape thickness or uneven winding.

FIG. 6 is a block diagram showing the main parts of the third embodiment of the present invention, and the blocks from 12 to 1 in FIG. 1 are replaced with the blocks shown in FIG.

Generally, in a two-head helical scan type VTR, recording and reproduction are performed by alternately switching two rotating heads B with different azimuth angles to increase the recording density. Therefore, in high-speed playback mode, the rotating head scans across the track, so the track recorded by the recording head is
When playing back with a head, the playback envelope level decreases, and the playback envelope waveform has a level that increases or decreases at a cycle depending on the tape transport speed.

Therefore, in the third embodiment, the actual tape speed is detected by paying attention to the period of this reproduction envelope level fluctuation. FIG. 7 shows the waveforms of each important part in FIG. 6, and the operation thereof will be described below, taking as an example the case of 10 times the speed explained in FIG.

In response to the head switching signal d supplied from the terminal 26, SW2 is regenerated from the rotary head 22J'22b, and the signals via the regenerative amplifiers 232L and 23b are sequentially switched and supplied to the regenerative envelope level detector 33. The level of this envelope signal (h) fluctuates at regular intervals for the reason mentioned above, and its reproduction level is detected and passed through the pulse shaping circuit 34 to obtain a pulsed signal like signal i.

Therefore, the first. As explained in the second embodiment, the period Tenv of this signal i is detected by the pulse period detector 17', and the reference value TN at N times speed is supplied from the terminal 30'' to the comparator 18''. , TN and T.nv, and if SWl is ON, the output C1 of the U/D counter is increased or decreased via the terminal 31''.

In the third embodiment, when the speed is N times (this differs between tape transport in the forward direction and in the reverse direction, only the case in the forward direction will be explained here), the rotating head crosses (N-1) tracks. Therefore, it is necessary to set the value according to the terminal 30''. (When performing cylinder relative speed correction, the correction factor α
Set to the value multiplied by ) As described above, in the third embodiment, since the level fluctuation of the playback envelope is utilized, the first . The same effects as in the second embodiment can be achieved.

As described in detail, according to the present invention, deviations in tape speed caused by variations in tape thickness, tape total length, reel hub diameter, etc., or uneven tape winding can be eliminated, and transfer control can be performed with high accuracy to a desired tape speed. can,
Its practical effects are enormous.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a VTR according to a first embodiment of the present invention, FIG. 2 is an operation waveform diagram of a main part of the same embodiment, and FIG. 3 is a main part of a VTR according to a second embodiment of the present invention. FIG. 4 is an explanatory diagram showing the recording magnetization locus of the 8mm VTR and head scanning during high-speed reproduction. FIG. 6 is an operational waveform diagram of the main part of the same embodiment. FIG. FIG. 7 is a block diagram of the main parts of the VTR in the third embodiment, FIG. 7 is an operation waveform diagram of the main parts of the same embodiment, FIG. 8 is a flowchart for explaining the operation of the first embodiment, and FIG. 9 is a conventional diagram. FIG. 2 is a block diagram of a tape drive device of FIG. 1... Supply reel, 2... Take-up reel, 12... Control head, 2o...
...Cylinder, 22&. 22b... Rotating head, 231L, 23b.
...Regenerative amplifier. Name of agent: Patent attorney Toshio Nakao and 1 other list
1 Figure Section d A q ^ ^ Hehe Figure 3 Figure 6 To ^ To He-e
l-! ! ,゛- Fig. 8

Claims (4)

[Claims] (1) A detection means for detecting information related to the rotation period of the supply reel and the rotation period of the take-up reel, and standards set in correspondence with the information detected by this detection means and the tape speed to be controlled. a calculation processing means for calculating a value; a tape transport control means for controlling tape transport based on the output result of the calculation processing means; and a tape transport control means for controlling tape transport based on the output result of the calculation processing means; 1. A magnetic recording and reproducing apparatus comprising: a tape speed detecting means for detecting by reproducing; and a correcting means for correcting the reference value based on information detected by the tape speed detecting means. (2) A magnetic recording/reproducing device having a control track in the longitudinal direction of a magnetic tape and recording a control signal of a constant frequency during recording, wherein the tape speed detecting means reproduces the control signal and the control signal is already recorded. A means for determining whether the control signal is recorded or not is provided, and when the determination means determines that the control signal has been recorded,
2. The magnetic recording and reproducing apparatus according to claim 1, wherein the tape transport speed is detected by detecting the period of the pulse obtained by reproducing the control signal. (3) When recording television video signals as a group of inclined, discontinuous recording tracks on a magnetic tape using a rotating magnetic head, pilot signals of four different frequencies are sequentially repeated for each field. A magnetic recording and reproducing device that records in a superimposed manner on a motion signal,
The tape speed detector is provided with a discriminating means for tuning one of the pilot signals and discriminating whether this pilot signal is recorded or unrecorded, and the discriminating means determines whether the pilot signal is recorded or not. 2. The magnetic recording and reproducing apparatus according to claim 1, wherein when it is determined that the tape transport speed is detected by detecting the period of a pulse obtained by tuning the pilot signal. (4) A two-head helical scan type magnetic recording and reproducing device in which recording and reproduction are performed by alternately switching rotary heads having two different azimuth angles, wherein the tape speed detection means is an envelope signal reproduced by the rotary head. A determining means is provided for detecting the playback level of the envelope and determining whether the television signal is recorded or unrecorded, and when the determining means determines that the television signal has been recorded, the level of the envelope is determined. 2. The magnetic recording and reproducing apparatus according to claim 1, wherein the tape transport speed is detected by detecting the period of the detected pulse.