JPH06319101A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To attain the search reproduction at a higher speed by which a stable reproduced picture is obtained with simple configuration. CONSTITUTION:A reproduced video signal from a magnetic tape 26 running at a high speed is fed to a memory 12 and a synchronizing signal HS is separated from the video signal by a synchronizing signal detection circuit 5 and a write clock phiw synchronously with the synchronizing signal HS is obtained from an oscillator 8 being a component of a PLL. An oscillated frequency of the oscillator 8 is suitably equivalent to a running speed of the magnetic tape 26 based on speed information representing the running speed of the magnetic tape 26 from a tape speed arithmetic circuit 29. The write in the memory 12 is executed based on the write clock phiw and the read from the memory 12 is executed based on a read clock phir having a predetermined frequency from an oscillator 15. Moreover, the magnetic tape 26 is subject to reel drive from a drive source 21 in the high speed search reproduction mode and controlled by a reel control circuit 17 so that its running speed is made constant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a helical scan type magnetic recording / reproducing apparatus, and more particularly to a magnetic recording / reproducing apparatus capable of performing high speed search / reproduction such as tens or hundreds of times the tape speed during recording. .

[0002]

2. Description of the Related Art As an example of a conventional magnetic recording / reproducing apparatus by a helical scan system which enables search reproduction for reproduction at a tape traveling speed higher than that at the time of recording, Japanese Patent Publication No. 63-51592 of the present inventors. Some of them are described in the gazette. This is because when the magnetic tape is run at a speed different from that at the time of recording, the relative speed deviation with the rotary head is large, so noise bars may flow on the screen and color misregistration may occur. By changing the rotation speed of the rotary head, the relative speed between the magnetic tape and the rotary head is made to match that at the time of recording. Further, as another example, Japanese Patent Laid-Open No. 1-21010
As described in Japanese Patent Laid-Open No. 75-75, although the field cycle changes in the reproduced video signal in the high speed variable speed reproduction mode,
This is to try to match the field cycle with a correct one by performing line interpolation or line thinning processing on the reproduced video signal using a one-field memory.

FIG. 21 shows tracks on the magnetic tape and scanning loci of the rotary head when the magnetic tape is stopped. As shown in the figure, tracks TR1 and TR2 formed on the magnetic tape 26 are , Along the track ST0 of the rotary head at the time of recording, is formed in an oblique direction with respect to the running direction of the magnetic tape 26.
A difference (shift) ΔST occurs between 1 and TR2. When the magnetic tape 26 on which such a track pattern is formed is stopped and scanned by the rotary head, when the rotary head is rotated at the same speed during recording, the scanning trace ST1 of the rotary head shows two tracks as shown in the figure. TR1,
It extends over TR2, and in this case, the scanning portion by this rotary head is increased by the portion of the difference ΔST.

FIG. 22 shows a track on the magnetic tape and a scanning locus of the rotary head when the magnetic tape is run at a high speed. As shown in the figure, the rotary head has the same speed during recording. 21 is rotated, the scanning locus ST2 of the rotary head extends over the two tracks TR1 and TR2 in the opposite direction to the case of FIG. 21, as shown in FIG. Will be reduced by the difference 6.

Here, in FIGS. 21 and 22, when the difference ΔST is expressed as α with the length of one horizontal scanning period of the video signal as a unit, it is reproduced at a double speed number N (N times the tape speed at the time of recording). The difference at that time is indicated by α × (N−1). The above Japanese Patent Publication No. 63-5159 tries to change the rotational speed of the rotary head so as to cancel this portion.
The method described in Japanese Patent Laid-Open No. 221075/1990 is a method described in Japanese Patent Laid-Open No. 221075/1990, in which line interpolation or thinning is performed after the data is once stored in a field memory. By the way,
NTS with L = 262.5 scanning lines in one field
In the C signal, the speed change of the rotary head is α × (N-1)
It becomes /262.5.

[0006]

When the high speed search is performed by the above conventional technique, the following problems occur.

1) Since a field memory is required,
Very expensive.

2) In order to easily perform the interpolation process, for example, it is conceivable to put a monochromatic signal or the like at the top and bottom of the screen.
The screen is crushed.

3) Performing line interpolation and thinning-out processing by arithmetic processing requires a very large-scale circuit.

4) When only the horizontal synchronizing frequency is adjusted without performing line interpolation and thinning processing, the vertical synchronizing frequency changes, so that the fast-viewing reproduction is about 20 times at the maximum depending on the performance of the television receiver. Can only speed up.

5) If the horizontal synchronizing signal is used for controlling the rotary head, the drive motor of the rotary head may run away or the rotation may become unstable unless complicated protection is applied.

6) In order to drive the magnetic tape at a high speed by the capstan control method, it is necessary to apply a high voltage to the capstan motor or to thicken the capstan shaft.

7) When shifting from the standard reproduction to the high speed search reproduction, a switching operation is required.

8) Furthermore, the current VHS type VTR has a plurality of recording modes such as standard speed and triple speed, and even if the magnetic tape is run at the same tape speed, if the recording mode is different, The playback speed is different. Therefore, when the tape is played back at a tape speed 100 times that of the standard mode, the portion recorded in the standard mode is 100 times faster, but the portion recorded in the triple mode is
The image is reproduced 300 times, and an image that can be recognized by human eyes is not reproduced.

An object of the present invention is to solve the above problems and to provide a magnetic recording / reproducing apparatus having a simple structure and capable of excellent image reproduction even at higher speed search / reproduction.

[0016]

To achieve the above object, the present invention relates to a memory means for storing a reproduced video signal for each one line, and a frequency of a writing clock of the memory means according to a tape running speed. And changing means, a means for generating a read clock having a constant frequency of the memory means, and a means for selecting a capstan driving method or a reel driving method as a tape driving method.

[0017]

Here, the memory is time-axis converted every time the memory is updated according to the frequency ratio of the write and read clocks, so it is also possible to fix the write side, change the read side, or both. However, it goes without saying that they all have the same effect.

Now, the above-mentioned memory means stores the video signal in units of one scanning line. At this time, when the signal is compressed on the time axis by the tape traveling speed, the signal is stored in synchronization with the clock signal of high frequency, and in the opposite case, the signal is stored in synchronization with the clock signal of low frequency, and the reading is performed with the clock of constant frequency. In sync with. Thus, even if the cycle of the sync signal due to the change in the relative speed is a reproduction signal far from the sync pull-in range of the television receiver, the cycle of the sync signal becomes a predetermined period within the sync pull-in range,
The time axis of the reproduction signal is restored. By this action,
The conversion of the sync signal into a signal within the sync pull-in range of the television receiver is performed, and the recorded contents can be viewed even when the tape is running at high speed.

Here, it is necessary that the write clock generating means has a wide operating area so as to be able to cope with running of the magnetic tape at an extremely high speed, and can obtain stable oscillation. However, the memory means may have a small capacity, and since the horizontal synchronizing signal is irrelevant to the control of the rotary head, the cylinder motor does not run away. Further, since the magnetic tape is run by the reel drive system and the driving force of the motor is directly transmitted to the reel stand, high-speed search reproduction at a tape speed 60 times or more that of standard reproduction becomes possible. In addition, by using the jog shuttle ring, etc., through a series of one operation, from standard playback to several times faster than the conventional fast-view playback, the drive control system of the magnetic tape is changed in the middle to change to the conventional fast-forward and wind. It is possible to run and reproduce the magnetic tape at a speed several tens of times faster than the case of the return. In addition to this, by discriminating the recording mode based on the correspondence between the tape running speed and the cycle of the reproduction control signal, it is possible to prevent the high-speed search speed from being abnormally increased due to the difference in the recording modes.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a magnetic recording / reproducing apparatus according to the present invention, in which 1 is a rotary head, 2 is a rotary cylinder, 3 is a reproducing amplifier, 4 is a switch, 5 is a sync signal detector, and 6 is a synchronizing signal detector. Phase comparator, 7 frequency divider, 8 voltage controlled oscillator, 9 adder, 10 filter, 11 A / D (analog / digital) converter, 12 memory, 13 write control circuit, 14 Is a D / A (digital / analog) converter, 15 is a fixed oscillator, 16 is a read control circuit, 17
Is a reel control circuit, 18 is a capstan control circuit, 19
Is a drive control switcher, 20 is a shuttle ring, 21 is a drive source, 22 is a reel drive switching mechanism, 23 is a capstan,
24 is a pinch roller, 25 is a control head, 26
Is a magnetic tape, 27 is a supply reel, 28 is a take-up reel,
Reference numeral 29 is a tape speed calculation circuit, 30 is a recording mode determination circuit, 31 is a voltage generation circuit, 32 is a signal processing circuit, and 33 is a television receiver (hereinafter referred to as a TV receiver).

In FIG. 1, a magnetic tape 26 runs spirally in contact with a rotary cylinder 2 over a predetermined angle range, and two rotary heads 1 mounted on the rotary cylinder 2 alternately rotate the magnetic tape 26. The reproduction video signal is reproduced by performing reproduction scanning. The reproduced video signals from these two rotary heads 1 are amplified by the reproduction amplifier 3 and then supplied to the switch 4 controlled by the switching control means (not shown) to become continuous reproduced video signals.

The reproduced video signal output from the switch 4 is supplied to the sync signal detector 5 to extract the sync signal HS on the one hand, and is converted to a digital video signal by the A / D converter 11 on the other hand. Are supplied to the memory 12.
In this memory 12, the digital video signal is time-axis converted as described later.

The sync signal HS from the sync signal detector 5 is
It serves as a reference signal of a PLL (Phase Lock Loop) including a phase comparator 6, a frequency divider 7, a voltage controlled oscillator 8, a filter 10 and the like. That is, a high frequency write clock φw is output from the voltage controlled oscillator 8, and this write clock φw is frequency-divided by the frequency divider 7 and supplied to the phase comparator 6 to synchronize with the synchronization signal detector 5. The phase is compared with the signal HS. The phase difference signal from the phase comparator 6 is the filter 1
The band is limited to 0, and the adder 9 adds the voltage signal vq from the voltage generating circuit 31 and supplies it to the voltage controlled oscillator 8 as the control voltage V. As a result, the oscillation frequency and the oscillation phase of the voltage controlled oscillator 8 are controlled so that the output signal φh of the frequency divider 7 and the synchronization signal HS from the synchronization signal detector 5 have a constant phase. Therefore, the frequency of the write clock φw output from the voltage controlled oscillator 8 changes when the frequency of the sync signal HS from the sync signal detector 5 changes.

Writing of the digital video signal from the A / D converter 11 to the memory 12 is performed in synchronization with the write clock φw from the voltage controlled oscillator 8, and one scanning scanning line ( The timing of accessing the head address of the memory 12 is required for each head of the line. This access is also made in synchronization with the reproduced sync signal. Therefore, the write control circuit 13 receives the synchronizing signal HS from the synchronizing signal detector 5 and generates this timing pulse from this and the writing clock φw, whereby the beginning of each line of the reproduced video signal leads to the beginning of the memory 12. Try to access the street address. Therefore,
The memory 12 may have a capacity of approximately 1H (1H is one horizontal scanning period).

Further, in the memory 12, the reading is performed in synchronization with the read clock φr having a constant frequency output from the fixed oscillator 15, but the read position of the memory 12 is returned to the head address at the read start timing for one line. There is a need. Therefore, the timing signal is generated by the read control circuit 16 counting the read clock φr.

The digital video signal read out from the memory 12 after time-axis conversion is converted into an analog video signal by the D / A converter 14 and then converted by the signal processing circuit 32 to produce an RF signal or a baseband signal. Is supplied to the TV receiver 33 as a video signal of

As will be described later, the tape speed calculating circuit 29 detects the tape speed and outputs the speed information indicating the tape speed. The voltage vq corresponding to this speed information is output from the voltage generating circuit 31 to adder. 9 is supplied. Therefore,
Write clock φw output from voltage controlled oscillator 8
Also changes in accordance with the output voltage vq of the voltage generation circuit 31, but the oscillation frequency of the voltage-controlled oscillator 8 has a very wide change range, and the output voltage vq of the voltage generation circuit 31 causes the same frequency as the tape running speed. It changes with the magnification. Therefore, even if the frequency of the reproduction synchronizing signal becomes N times, the frequency of the write clock φw also becomes N times. Therefore, the time axis is converted to 1 / N times by the memory 12, and the reproduced image accompanying the change of the tape running speed is generated. The change in the time axis of the signal is canceled out, and the video signal of the original frequency is obtained. This is also the case when the reproduction is performed at an extremely high tape running speed because the oscillation frequency change range of the voltage controlled oscillator 8 is very wide, and the memory 12 performs a very wide time axis conversion operation. become.

Next, the tape drive system of this embodiment will be described. As a tape drive system, a magnetic tape is held between a pinch roller and a capstan, and a capstan drive system in which the capstan is rotationally driven to run the magnetic tape, and a reel base is rotationally driven to run the magnetic tape. There is a reel drive system.

In FIG. 1, the capstan drive system is
Attach the magnetic tape 26 to the capstan 23 and the pinch roller 24.
The magnetic tape 26 is run by rotating the capstan 23 with a drive source 21 such as a capstan motor, thereby ensuring the tape tension. Therefore, the rotary head of the magnetic tape 26 can be secured. The hit to 1 (head touch) is also good, and it is suitable for low speed and constant speed tape running such as reproduction and recording. Although the capstan drive system is used in the conventional tape speed in the quick-play (search) reproduction, the capstan drive system causes the magnetic tape 26 to run at an unprecedentedly high search speed as in this embodiment. In this case, it is necessary to apply a high voltage to the drive source 21 to rotate it at a high speed.

In the reel drive system, since the supply reel base 27 or the take-up reel base 28 is directly or separately driven by a single motor to drive the magnetic tape 26, the driving force is strong. In particular, it is suitable for running the magnetic tape 26 at high speed such as rewinding and fast-forwarding. In this embodiment, a single drive motor is used, which is why the supply reel base 2
A reel drive switching mechanism 22 for selectively transmitting a driving force is provided to either one of the winding reel base 28 and the winding reel base 28.

As described above, while the supply reel base 27 and the take-up reel base 28 are selectively driven by the single drive source 21, it is often adopted to provide a drive source for each reel base. However, also in this embodiment, a drive source may be provided for each reel stand. As will be described later, due to a mechanical problem, the control at the time of shifting from the normal reproduction to the search reproduction is different between the case of using the single motor and the case of using the motor for each reel stand. However, in any case, what is needed is a faster search speed than ever before.
Any control system capable of obtaining a stable head touch at a relatively high speed in order to view the playback screen on the screen is acceptable. Such an example already exists as a known technique (for example, “Technical Report of the Television Society”, 1990, August).
Moon, VOL. 14, No 41, pp. 7 to 12, "Tape drive system for composite digital VTR (D2)" and the like).

By the way, in this embodiment, the magnetic tape 2 is used.
The drive control switching device 19 selects whether the traveling drive of 6 is the reel drive system or the capstan drive system according to a command from the shuttle ring 20. The drive system and its switching are performed by the reel control circuit 1
7. Capstan control circuit 18 and drive control switching device 19
However, this may be performed by a microprocessor.

In this embodiment, the above-mentioned two driving methods are used together to drive the magnetic tape 26, but the conventional search reproduction (this is a search reproduction of several times the standard reproduction. It is called low-speed search playback.
In the following, search reproduction of about several tens of times of standard reproduction is referred to as high-speed search reproduction). In the case of high-speed search reproduction, the magnetic tape 26 is run by the capstan drive system.
The magnetic tape 26 is made to run by a reel drive system. As a result, conventional low-speed search reproduction and unprecedented high-speed search reproduction can be realized without newly applying a high voltage to the capstan motor or changing the capstan shaft to be thick.

The tape drive system switching mechanism and its operation will be described below. FIG. 2 is an explanatory diagram of the shuttle ring 20 in FIG. In the figure, when the shuttle ring 20 is set to the neutral position,
Directs normal (normal) playback. When the shuttle ring 20 is turned to the right, for example, a fast-forward search reproduction is commanded. At this time, the tape running speed changes according to the rotation angle of the shuttle ring 20 and the search speed changes. However, at the preset rotation angle a, the low speed search reproduction mode (conventional search mode) is commanded. Then, the magnetic tape 26 is held by the pinch roller 24 and the capstan 23 and runs. At this time, the drive control switching device 19
Selects the capstan control circuit 18, whereby the capstan drive system in which the drive source 21 is controlled is performed.

In the rotation angle region b exceeding the rotation angle region a, the high speed search reproduction mode is commanded and the magnetic tape 26
Is released from being pinched by the pinch roller 24 and the capstan 23, and the mechanical section enters a state similar to the conventional fast-forward mode in which the take-up reel base 28 is drive-controlled to run the magnetic tape 26 at high speed. Therefore, at this time, the drive source 2
The driving force of 1 is transmitted to the take-up reel base 28 via the reel drive switching mechanism 22, and the drive control switching device 19 switches from the capstan control circuit 18 to the reel control circuit 17 to control the drive source 21. Thus, the traveling control of the magnetic tape 26 is switched to the reel drive system. In this way, the magnetic tape 26 runs at high speed by the reel drive system.

In the prior art, the reel drive mode is simply a fast-forward mode in which the magnetic tape 26 is wound at high speed, but in this embodiment, reel control is performed based on tape speed information from the tape speed calculation circuit 29. The circuit 17 controls the drive source 21 so that the traveling speed of the magnetic tape 26 is constant, so that the magnetic tape 26 is stably run at high speed. Moreover, the recording mode discriminating circuit 30 discriminates whether the recording mode is, for example, the standard mode or the triple mode, and according to the discrimination result, the magnetic tapes 26 recorded in different modes are recorded again. The traveling speed of the magnetic tape 26 is controlled for each part of the same magnetic tape 26 where the recording mode is different so that the double speed of the search speed in the high speed search reproduction is made equal in any recording mode. That is, the shuttle ring 20
When a 0x speed high speed search / playback is instructed, a recording mode determination circuit is provided so that 100x speed high speed search / playback can be performed even if the recording mode is the standard mode or the 3x mode. The reel control circuit 17 controls the drive source 21 based on the determination result of 30.

In the case of a magnetic recording / reproducing apparatus which can set only one recording mode (standard mode), this recording mode discrimination circuit 30 is not necessary. When the shuttle ring 20 is turned to the left from the neutral position, the rewinding search is performed, but the operation is exactly the same as above.

An example of the reel drive switching mechanism 22 is described in detail in, for example, Japanese Unexamined Patent Publication No. 2-49252, and the description thereof is omitted here, but a mechanism system of a VTR equipped with this example is illustrated. 4 shows. However, the same figure (a)
Is a top view thereof, and FIG. 7B is a bottom view thereof. In this example, the drive source for driving the reel is a capstan motor.

By the way, as in this embodiment, V for consumer use is used.
In the case of TR, there is often a single drive source due to cost and other reasons, and as in the above example, the drive force of the capstan motor is transmitted mechanically by switching to two reel stands. There is. For this reason, only one of the capstan drive and the reel drive can be controlled. If the capstan drive system is directly switched to the reel drive system, the magnetic tape 26 is burdened.

Therefore, in this embodiment, when the capstan drive system is changed to the reel drive system, or vice versa, the mechanism is once put in the stop mode to mechanically switch the transmission of the driving force. , So that the next tape drive method is entered. In this way, since the tape drive system is switched through the temporary stop mode, the magnetic tape 26 is not burdened. As a result, the tape drive system can be switched by simply rotating the shuttle ring 20 without pressing the operation button again, and the tape running speed during normal reproduction can be changed to the tape during conventional fast forward or rewind. It is possible to change the traveling speed of the magnetic tape 26 up to the traveling speed (for example, 60 times the standard reproduction) without imposing a burden on the magnetic tape 26,
In addition, even if the tape running speed is changed to such an extremely high speed as described above, the image can be always reproduced.

The high-speed search reproduction using both the capstan drive system and reel drive control has been described above.
The search reproduction may be performed only by the reel drive system. However, in this case, the shuttle ring 20
You can switch from the standard playback mode to the high-speed search playback mode directly by operating. Even in this case, needless to say, it is possible to take a method such as not applying a load to the magnetic tape 26 at the time of switching the tape driving method as described above. When performing high-speed search reproduction only with the capstan drive system, mechanical switching from normal reproduction is of course unnecessary.

FIG. 3 shows the tape speed calculation circuit 2 in FIG.
9 is a block diagram showing a specific example of 9, in which 34 is a speed calculation unit based on a control signal CTL, and 35 is FG (Fr
A speed calculator based on an "equency Generator" pulse, and 36 is a speed information addition circuit.

In the figure, the tape speed calculation circuit 29
Is a circuit for calculating the speed at which the magnetic tape 26 is actually running. Magnetic tape 26
As a method of actually measuring the traveling speed of (1) the magnetic tape 26 by the control head 25
Method of measuring and calculating the cycle of the control signal CTL reproduced from (2) FG pulse generated when the capstan 23 and the reel stands 27, 28 rotate (in FIG. 1, the capstan 2
The FG pulse generated by the rotation of 3 is CFG, the FG pulse generated by the rotation of take-up reel table 28 is TFG, and the FG pulse generated by the rotation of supply reel table 27 is SFG). Stand 27,2
There is a method of calculating the rotation speed of No. 8 and calculating from these, but in this embodiment, these methods are used together.

That is, in FIG. 3, the speed calculator 34 obtains the tape speed and the running direction from the reproduced control signal CTL by the method (1), and the speed calculator 35.
Determines the tape speed and running direction from the FG pulses CFG, TFG, SFG by the method (2). The obtained speed information is supplied to the speed information addition circuit 36 and added at a predetermined addition ratio. As this addition ratio,
For example, a predetermined weighting such as 1: 1 may be performed to obtain the arithmetic average of these, and when the control signal CTL is reproduced, the speed information from the speed calculator 34 is reproduced by the control signal CTL. If not, the speed information from the speed calculator 35 may be selected and output by the speed information addition circuit 36, respectively. The speed information output from the speed information adding circuit 36 indicates the actual running speed and running direction of the magnetic tape 26, and is supplied to the reel control circuit 17 and the capstan control circuit 18 of FIG. It is supplied to the circuit 31.

When the speed information from the speed calculators 34 and 35 is arithmetically averaged as described above, the tape running speed is obtained from the speed information obtained by different methods.
Improves tape speed measurement accuracy. Further, in this case, when the control signal CTL is not recorded or cannot be reproduced for some reason, by changing the addition ratio of the speed information addition circuit 36, the speed information from the speed calculation unit 35 remains that value. The speed information adder circuit 36 outputs it.

The recording mode discrimination circuit 30 in FIG. 1 will be described. For example, in the case of the VHS system VTR, there are a standard mode and a triple mode as recording modes, but during high speed search reproduction, the recording mode is 1 in the standard mode part.
When the tape reproduction speed is the same as that of the 00-times speed search reproduction and the reproduction is performed in the recording mode of the 3-times mode, the search reproduction becomes 300 times and the image cannot be recognized by human eyes. Therefore, even when the recording mode is the triple mode, it is necessary to slow down the running speed of the magnetic tape 26 so that the search reproduction is 100 times as in the standard mode. That is, in the case where the portions having different recording modes are sequentially reproduced and scanned, the shuttle ring 20
If the rotation angle in (Fig. 1) cannot be changed, it is necessary to perform search reproduction at the same double speed. For this purpose, the tape traveling speed at the time of reproduction must be different depending on the recording mode. Need to be made.

The recording mode discriminating circuit 30 discriminates the recording mode not only during normal reproduction but also during search reproduction from the relationship between the cycle of the reproduced control signal CTL and the tape running speed. By supplying the recording mode information to the tape speed calculation circuit 29,
In each recording mode, the recording mode is constantly monitored so that the tape traveling speed does not become abnormal. As a result, even if the recording mode is different, the search speed corresponding to the rotation angle of the shuttle ring 20 can be obtained.

In FIG. 1, the capstan control circuit 18, reel control circuit 17, tape speed calculation circuit 2
9. A series of operations by the recording mode discriminating circuit 30 and the voltage generating circuit 31 can be easily realized by a system controller, a dedicated microprocessor, or the like.

Next, the time axis conversion operation of the memory 12 of FIG. 1 will be described. Taking the NTSC system as an example, the frequency of the horizontal synchronizing signal of the video signal is 15.75 kHz and its period is 63.5 μsec. Therefore, in FIG. 1, during normal reproduction in which reproduction is performed at the same tape running speed as during recording, as shown in FIG. 5A, the cycle of the synchronization signal HS detected by the synchronization signal detector 5 is 63.5 μsec. Is. Here, the oscillation frequency of the voltage-controlled oscillator 8 during normal reproduction, that is, the frequency of the write clock φw is set to 20M.
If the frequency is Hz, the A / D converter 11 sets the band of the video signal to 1
It is possible to secure up to about 0 MHz. The cycle of the write clock φw at this time is 50 nsec. The frequency divider 7 divides this write clock φw by 1270 to obtain almost 1
The frequency-divided signal φh of 5.75 kHz is output. The oscillation phase of the voltage controlled oscillator 8 is controlled by the output of the phase comparator 6 so that, for example, the rising edges of the divided signal φh and the write clock φw are in phase synchronization.

Next, the high speed search reproduction will be described by taking the 60 × speed search reproduction as an example. In the case of forward high-speed search reproduction (+60 double speed search reproduction) in which the magnetic tape 26 is run in the forward direction, the double speed number is N (= 60) and the number of lines α of the difference ΔST is 1 as described with reference to FIG. Assuming that the number of lines in the field is L, the frequency change amount of the synchronization signal HS output from the synchronization signal detector 5 in N times high speed search reproduction is Δv = −α × (N−1) / L (1 ) And α = 1.5 (standard mode), N = 60, L = 2
62.5, Δv = −0.337, and the frequency of the synchronization signal HS is 33.
7% lower. Therefore, as shown in FIG. 5B, the cycle of the synchronization signal HS is about 85 μsec.

Further, in the case of reverse high-speed search reproduction (-60 × speed search reproduction) in which the magnetic tape 26 is run in the reverse direction, N = -60, Δv = 0.339, and the frequency of the synchronizing signal HS is changed. About 34% increase. Therefore, as shown in FIG. 5C, the period of the synchronization signal HS is about 42 μsec.

As described above, when the high-speed search reproduction of 60 times speed is performed, the frequency of the reproduction synchronizing signal largely changes, and in this embodiment, the rotational speed of the rotary head 1 does not change (even if it changes. In the narrow range such as the pull-in range of the synchronizing circuit of the television receiver 45, for example, the change is about 10%), and the frequency of the synchronizing signal is 15.75 kHz by the small-capacity memory 12.
The digital video signal is time-axis converted so that
This will be described below. However, in this embodiment, the number of rotations of the rotary head 1 is not changed during high-speed search reproduction.

As described above, the frequency of the reproduction synchronizing signal HS is reduced by 33.7% in the +60 times high speed search reproduction. In response to this, the voltage generation circuit 31 outputs a voltage vq lower than that during normal reproduction, based on the speed information from the tape speed calculation circuit 29. As a result, the output control voltage V of the adder 29 is lowered, and the oscillation frequency of the voltage controlled oscillator circuit 28 is lowered. Further, in the high-speed search reproduction of -60 times speed, the frequency of the reproduction synchronization signal HS is increased by about 34%. Therefore, the voltage generation circuit 31 normally reproduces the speed information from the tape speed calculation circuit 29 so as to follow this. It outputs a voltage vq higher than the time. As a result, the adder 29
Output control voltage V becomes high and the oscillation frequency of the voltage controlled oscillator circuit 28 becomes high.

In this way, the ratio between the frequency of the synchronizing signal HS and the frequency of the write clock φw is always kept constant regardless of the search speed. In the +60 times high speed search reproduction, the period of the write clock φw becomes 67 μsec as shown in FIG. 5B, and in the −60 times high speed search reproduction, as shown in FIG. The cycle becomes 33 μsec. That is, regardless of the search speed, the write clock φ in one cycle of the synchronization signal HS
The wave number of w is always constant (1270, which is equal to the frequency division ratio of the frequency divider 7 in this embodiment).

Therefore, the number of samples per line of the video signal digitized by the A / D converter 11 is always 12.
The write clock φw is always 70 in phase with the synchronizing signal HS, and the number of samples written in the memory 12 in synchronization with the write clock φw is constant at 1270 for one line. By reading this with the read clock φr of 20 MHz, a constant digital video signal with a frequency of the synchronizing signal HS of 15.75 kHz can be obtained regardless of the search speed.

Here, assuming that the voltage controlled oscillator 8 is a general varicap diode oscillator, the control voltage V of the voltage controlled oscillator 8 supplied from the adder 9 and the oscillation frequency (the frequency of the write clock φw). ) The relationship with f is
As shown in FIG. If the relationship between the search speed B and the required frequency f of the write clock φw is shown in FIG. 7, the frequency output characteristic of the adder 9 with respect to the search speed B is as shown in FIG. . As shown in FIG. 9, the control voltage V is composed of a phase control voltage vp output from the filter 10 in the PLL circuit and an output voltage vq of the voltage generating circuit 31. This voltage vq
Is constant once the playback mode is determined.

In FIGS. 6 to 9, f ₀ , V ₀ , B
₀ is for normal reproduction, and f ₁ , V ₁ , and B ₁ are +
F ₂ , V ₂ , and B ₂ at 60 × speed are for high-speed search reproduction at −60 × speed, respectively.

By the way, in the case of a home VTR, in order to increase the information recording density, it is general to use an azimuth recording system in which recording is performed on adjacent tracks without a guard band by rotating heads having different azimuth angles. However, when a color video signal is recorded and reproduced, the luminance signal is FM-modulated and the color signal is converted into the low frequency range. Since the low frequency conversion is performed, the recording frequency is low. This azimuth recording method is not effective, and interference components from adjacent tracks are mixed during reproduction.

For this reason, the color signal is recorded with the phase of the color subcarrier shifted or inverted by 90 degrees for each line, and during reproduction, by adding the color signals of adjacent lines, The disturbing component from the adjacent track is removed.

Further, in order to stabilize the color demodulation in the subsequent stage, when frequency conversion is performed on the reproduction color signal which has been low-pass converted to the original band, the time axis fluctuation of the color signal caused by recording and reproduction is removed. A color phase stabilizer is provided so that the color burst signal serving as the phase reference of the reproduced color signal is automatically locked to a constant reference (subcarrier) signal.

FIG. 10 illustrates the color processing of a general VHS type VTR. See, for example, Minoru Inazu, "Recording and Reproduction of Images", published by Corona Publishing Co., pp. 408 to 411 and the like. Here, 26 is a magnetic tape, C
TR is a control track, A / TR is an audio track, TR1 and TR2 are video tracks adjacent to each other, and L
S is a recording section of one line, 37 is a phase shift circuit, 38
Is a 1H (1H is one line period) delay circuit, and 39 is an adder. The arrows in the circles shown in the recording sections LS of the video tracks TR1 and TR2 indicate the phases of the recorded color signals.

In the figure, each video track TR1, T
In R2, the phase of the color signal is shifted by 90 degrees for each recording section LS, and the phase shift directions of the adjacent video tracks TR1 and TR2 are opposite to each other. At the time of reproduction, the phase of the color signal reproduced from the video tracks TR1 and TR2 is shifted by 90 degrees for each line in the direction opposite to that at the time of recording, and is added to the color signal obtained 1H time ago from the 1H delay circuit 38. Add with the device 39. As a result, the color signal from which the interfering components from the adjacent tracks are removed can be obtained.

However, if the reproduced color signal has a time axis fluctuation due to fluctuations in the running speed of the magnetic tape, the time length of one line deviates from the regular 63.5 μsec, and the color signal processing cannot be performed. For this purpose, the color phase stabilizer described below is used.

FIG. 11 is a pp. 1 of "Recording and Reproducing Image" issued by Corona. It is a block diagram which shows the color phase stabilizer described in 205, 40 and 41 are frequency oscillators, 42 is a filter, 43 is a color burst signal extractor, 44 is a phase comparator, 45 is a voltage controlled oscillator, 46 Is a reference (subcarrier) signal generator.

This is provided in the preceding stage of the phase shift circuit 37 in FIG. 10, is phase-synchronized with the reproduced color signal with many time axis fluctuation components, and obtains a stable color reference (color subcarrier) signal. is there.

In FIG. 11, the reproduction color signal which has been converted into the low frequency band is supplied to the frequency converter 40, and is multiplied by the output signal of the frequency converter 41 containing the same time axis fluctuation component as the reproduction color signal. As a result, the reproduced color signal is converted into the original frequency domain in which the subcarrier frequency is 3.58 MHz, and the time axis fluctuation component is removed. The output signal of the frequency converter 40 is supplied to the filter 42, a color signal having no time-axis fluctuation component is extracted, and the processing described with reference to FIG. The color signal output from the filter 42 is supplied to the color burst signal extractor 43 to extract the color burst signal, and the color burst signal is extracted by the phase comparator 44 from the reference signal generator 46.
The phase is compared with the reference signal of 58 MHZ, and the time axis fluctuation component included in the input reproduction signal is detected as the phase error voltage. The oscillation frequency of the voltage-controlled oscillator 45 is controlled by this phase error voltage, whereby a signal including the same time-axis fluctuation component is output at a frequency equal to the subcarrier frequency of the input reproduction color signal. The output signal of the voltage-controlled oscillator 45 is frequency-converted by the frequency converter 41 by the reference signal having the frequency of 3.58 MHz from the reference signal generator 46, and this is supplied to the frequency converter 40.

However, in the case of high-speed search reproduction, the time length of one line largely deviates from the regular 63.5 μsec, and since it varies depending on the search speed, the color signal processing described in FIG. 10 cannot be performed. According to the above-mentioned color phase stabilizer, the time base fluctuation of the color signal due to the fluctuation of the running speed of the magnetic tape can be removed to some extent, but this can be removed only for about 1 μsec, which is the case in the high speed search reproduction. The time length of one line is 63.5μs
If it deviates significantly from ec, even if the color signal is processed by the color phase stabilizer, the processing described in FIG. 10 cannot be performed.

Further, since the color phase stabilizer performs feedback control, it takes some time before its effect is exhibited. For example, once control is disturbed by a disturbance, 7-10 lines (7-1
It takes about 0 H), and in the case of a very low-speed search playback like the conventional one, the interval from the noise bar to the next noise bar is secured and the recovery is possible.
In the case of the high speed search reproduction as described above, the effect cannot be obtained.

Therefore, in FIG. 1, when recording and reproducing a color video signal as described above, for example, such a color phase stabilizer is provided in the preceding stage of the A / D converter 11 and frequency conversion of the color signal and up to about 1 μsec. The time-axis fluctuation component is removed, and the signal processing circuit 32 removes the interference component in the color signal shown in FIG. According to this, the time length of one line becomes the regular 1H period length by the memory 12 even during high-speed search reproduction.
The process described in 0 can effectively remove the interference component from the adjacent track.

However, during high-speed search reproduction, since the rotary head frequently scans across tracks (track jump), the above-mentioned color signal processing is not satisfactory, and a desired color may not be reproduced. May cause fading. The cause and the measures against this in this embodiment will be described below.

FIG. 12 shows a pattern of track jumps and a phase shift of color signals at the same time during high-speed search reproduction. TR represents a track (actually, it is necessary to consider azimuth recording or the like. , ST is a simplified trace), ST is a scanning trace of the rotary head during high-speed search reproduction, A and B are track jump points, and HD is a recording position of a synchronization signal.

As shown in the figure, during high speed search reproduction,
Track jumps occur frequently (positions A and B) and in a short time. At this time, the continuity of the phase of the color signal is impaired, and in particular, if there is a track jump during line scanning such as the track jump point B, a color error will occur.

In order to solve this, as one of the methods, the write timing of the memory 12 is controlled. That is, the track jump point is uniquely determined from the relationship between the tape running direction, the tape running speed, and the deviation of the scanning track of the rotary head with respect to the track at the start of scanning by the rotary head, and thus the line including the track jump point Is to prevent writing to memory.
In FIG. 1, the tape running direction and the tape running speed can be detected by the tape speed calculation circuit 29, and the deviation of the scanning locus of the rotary head with respect to the track at the start of the scan of the rotary head is controlled by the rotational phase of the rotary head 1 and the control. Since it can be detected from the phase relationship with the control signal CTL reproduced by the head 25, the write control circuit 13 may be controlled so as not to write the line including the track jump point in the memory 12 according to these detection results.

Furthermore, in the case of high speed search reproduction,
In a memory that performs time-axis conversion such as the memory 12, since the writing speed and the reading speed are different, the writing phase in the memory overtakes the reading phase, and conversely, the reading phase overtakes the writing phase. There is a problem that writing and reading are simultaneously performed at the same address. This will be described below with reference to FIGS. 13 and 14 by taking a high-speed search reproduction of forward / reverse 60 times speed as an example.

First, in the case of reverse high-speed search reproduction, the writing phase and the reading phase of the memory are respectively as shown in FIG.
It is shown by (b). However, these numbers indicate line numbers. In this case, since the frequency of the reproduction signal becomes high, the cycle of the horizontal synchronizing signal becomes short. Since this is read from the memory so as to have the same frequency as that at the time of recording, the write phase is faster than the read phase, and the write phase overtakes the read phase. This overtaking timing is shown as tp. For example, if the write phase exceeds the read phase at the stage of reading to the middle of the second line (time point tp), the information of the third line starts to be written in the memory during the reading of the second line.
At the time point tp at which all the information of the line is not read, the write phase exceeds the read phase, and the information of the third line is read from the middle of the second line. Therefore, the information of the second line and the information of the third line are joined in the middle of the line.

This not only impairs the continuity of the phase of the color signal described above, but is also not preferable in the control of the memory. This is because writing and reading are simultaneously performed at the same address of the memory at the time point tp, and the operation in this case may not be guaranteed depending on the memory.

In order to avoid this, the write control circuit 13 in FIG. 1 controls the memory write so that the line in which this overtaking occurs is not written in the memory.

That is, as shown in FIGS. 13A and 13B, assuming that the above-mentioned overtaking occurs during the writing of the lines 3, 5, and 8, the write control circuit of the memory is shown in FIG.
The write stop signal shown in FIG. 13C is generated so that the lines 3, 5 and 8 are not written in the memory as shown in FIG. As a result, as shown in FIG.
From this memory, each line is read as 1, 2, 4, 6, 7, ... With a regular period length of 63.5 μsec and without switching to information of other lines in the middle of the line. .

Here, although the lines 3, 5, 8 and the like are missing, the time length of the line to be read is regular and the rotation speed of the rotary head 1 is the same at the time of recording. The number of lines in the field period is a regular 262.5.

In the case of the forward high speed search reproduction, the writing phase and the reading phase of the memory are shown in FIGS. 14 (a) and 14 (b), respectively.
Indicated by. In this case, since the frequency of the reproduction signal becomes low, the cycle of the horizontal synchronizing signal becomes long. Since this is read from the memory so as to have the same frequency as that at the time of recording, the read phase is faster than the write phase, and the read phase overtakes the write phase. This overtaking timing is shown as tq. For example, if the read phase overtakes the write phase at the stage of writing to the middle of the third line (time point tp), as shown in FIG. 14B, the information of the second line will be present in the middle of the third line to be read. It has been inserted.

In order to prevent this, two memories are used, and writing and reading are controlled respectively. This will be described with reference to FIGS.

Here, assuming that the read phase is overtaken as shown in FIG. 14A, lines 1 and 2 are written in the first memory as shown in FIG. 14C. Then, from the next line 3 to the line where the next overtaking occurs, as shown in FIG. 14 (e), the data is written in the second memory. Then, as shown in FIG. 14D, lines 1 and 2 are read from the first memory, the same line 2 is read from the first memory, and then the second line is read. From memory line 3,4
Read as 5. In this case, if the line 3 of the second memory is immediately read after the first read of the line 2 from the above-mentioned first line, FIG.
The same read phase overtaking as described in (a) and (b) occurs, but the second read of line 2 from the first memory results in sufficient write of line 3 in the second memory. , And then the third read,
The read phase overtaking as described above does not occur.

FIG. 14 (g) shows the write control timing of the first and second memories. When the write control timing is "L", the first memory is shown, and when it is "H", the second memory is shown. The write mode is entered and this switching occurs at time t ₁ .
Further, FIG. 14 (h) shows the read control timing of the first and second memories. When this is "L", the first memory is read, and when it is "H", the second memory is read. The mode is entered and this switching occurs at time t ₂ .

FIG. 15 shows an embodiment of a magnetic recording / reproducing apparatus according to the present invention which can prevent the read phase from overtaking the write phase in this way. However, 12A, 12B
Is a memory, 47 is a read / write activation control circuit, 48, 4
9 is a reset signal generation circuit, 50 is a switch circuit, 5
Reference numerals 1 and 52 denote drive sources, and parts corresponding to those in FIG.

In FIG. 12, drive sources 51 and 52 are provided for each of the supply reel base 27 and the take-up reel base 28 in this embodiment, and the drive sources 51 or 5 are provided during high speed search reproduction.
It is assumed that the reel is driven by 2. Therefore,
The drive source 21 is a drive source dedicated to the capstan 23. Of course, as in the embodiment shown in FIG.
The drive sources of 7, 28 and the capstan 23 may be common.

In this embodiment, as described above, 2
One memory 12A, 12B is used, and FIG.
In the operation described in (f), two memories 12 are
A and 12B operate simultaneously. In addition, FIG.
In the operation described in (e), the memories 12A, 12
Either one of B is operated.

Similar to the embodiment shown in FIG. 1, the write clock φw from the voltage controlled oscillator 8 and the synchronizing signal HS from the synchronizing signal detecting circuit 5 are supplied to the reset signal generating circuit 48, and the writing reset signal RSW. Is generated. By this write reset signal RSW, the memories 12A, 1
2B is simultaneously reset every time the line of the digital video signal from the A / D conversion circuit 11 is started, and the writing address becomes the leading address. Similarly, the read clock φr from the fixed oscillator 15 is counted by the reset signal generation circuit to generate the read reset signal RSR, and the read address of the memories 12A and 12B is reset to the leading address by the read reset signal RSR. It

The tape speed calculation circuit 29 generates and outputs the speed information VI and the traveling direction information DI of the magnetic tape 26 in the same manner as the embodiment shown in FIG. The information and the write reset signal RSW and the read reset signal RSR are supplied from the reset signal generation circuits 48 and 49 to the read / write activation control circuit 47, and based on these information, the write activation signal WE1 of the memory 12A. The read activation signal RE1, the write activation signal WE2 and the read activation signal RE2 of the memory 12B are generated.

The memories 12A and 12B perform the write operation when the write activation signals WE1 and WE2 are "L",
When the read activation signals RE1 and RE2 are "L", the read operation is performed. This "L" write activation signal WE
1, WE2 and read activation signals RE1, RE2 are appropriately set to perform the operation shown in FIGS. However, in the case of the operation shown in FIG. 13 for the reverse direction high speed search reproduction, the write activation signal WE1 and the read activation signal RE1, or the write activation signal WE2 and the read activation signal RE2 are set to "H". As a result, only one of the memories 12A and 12B is operated.

The conditions for the write phase to overtake the read phase in the case of reverse high speed search reproduction will now be described.

In this case, in the memories 12A and 12B, the line length to be written is shorter than the line length to be read, and the writing speed is faster than the reading speed. Therefore, in FIG. Assuming that the line that is formed is line N, as shown in FIG.
The writing start time point tb of the line N must be before the reading start time point tb "of the line N shown in FIG. 16C. In this case, by the time the reading end time point te" of the line N is reached. Since the writing of the line N is completed (time point te), the line N is continuously read to the end.

When such a condition is satisfied, the line length to be written is shorter than the line length to be read, so writing of the next line (N + 1) is started during the reading period of the line N. 16), if the time t e ′ at which the last sample of this line (N + 1) is written is later than the read time t e ″ of the last sample of the line N shown in FIG. 16C, then the line (N +
The write phase of 1) does not overtake the read phase of line N.

As described above, from the reading start time tb "of the line N shown in FIG. 16 (c) to the time t shown in FIG. 16 (b).
If the writing of the line is not started within the period Ta up to b ′, that is, the period T that starts at the time of the read reset signal RSR from the reset signal generation circuit 49 (FIG. 15).
If the write reset signal RSW is not generated from the reset signal generation circuit 48 (FIG. 15) in a, the write phase does not overtake the read phase of the line N. here,
Since the time length of one line depends on the search speed, and the time length of this period Ta is determined by the line length, this period Ta is the search speed, and therefore the speed information VI from the tape speed calculation circuit 29 of FIG. Will be uniquely determined by

From the above, FIG. 17 determines whether or not the write phase is overtaken and determines whether the write activation signal WE1 or WE
FIG. 14 is a block diagram showing a specific example of means for generating the write stop signal shown in FIG.
Is a monostable multi, 54 is a D-type flip-flop, 55 is a resistor, 56 is a transistor, 57 is a capacitor, and 58 is a D / A conversion circuit. This means is included in the read / write activation circuit 47 of FIG.

In the figure, the digital speed information VI from the tape speed calculation circuit 29 is the D / A conversion circuit 58.
And a pulse having a constant time length is formed with a voltage according to the speed information VI. The transistor 56 is turned on during this pulse, and a current having a magnitude corresponding to the pulse voltage during this period flows through the resistor 55 and the transistor 56 to charge the capacitor 57. This charging voltage determines the time constant of the monostable multi 53.

Therefore, with reference to FIG. 18, the monostable multi 53 is triggered by the read reset signal RSR from the reset signal generating circuit 49 of FIG. 14, rises at the timing of the read reset signal RSR, and the capacitor 57 is charged. A pulse MM having a time width determined by a time constant corresponding to the voltage is generated. The "H" period of the pulse MM is the period Ta shown in FIG. This pulse MM is
The write reset signal RSW from the reset signal generation circuit 48 of FIG. 15 is supplied as a data input to the D-type flip-flop 54 that uses the trigger pulse. The Q output of the D-type flip-flop 54 is the write stop signal WDE shown in FIG. 13C, but as shown in FIG. 18, the write reset signal R is generated within the period Ta of "H" of the pulse MM.
When there is a SW, the write stop signal WDE becomes "H" from the timing of the write reset signal RSW, and writing of the line following the write reset signal RSW to the memory 12A or 12B is prohibited.

The capacitor 57 is charged only when the backward high speed search reproduction is started, and the capacitor 57 is discharged by means not shown at the end of the backward high speed search reproduction operation.

Further, in the one of the memories 12A and 12B which does not operate, both the write activation signal and the read activation signal are "H".

In the case of high-speed search reproduction in the forward direction, the reading speed is faster than the writing speed in the memories 12A and 12B, and the reverse of the above.

That is, in FIG. 19, the write phase of the memory 12A or 12B is shown in FIG.
It is assumed that (c) shows the read phase, respectively.

If the read start time point tb 'shown in FIG. 19 (b) is slightly advanced with respect to the write phase of the line N shown in FIG. 19 (a), the immediately preceding line (N-1) will be read. However, if the read phase does not pass the write phase, the line N is read out immediately after the line N is written, and the read phase is overtaken. Further, if the end point te ″ of the read period of the line N shown in FIG. 19C is at least delayed from the write end point tb of the line N shown in FIG. 19A, the read phase may not be overtaken. Absent.

Therefore, when there is no read reset signal RSR within the period Tb from the timing of the write reset signal RSW in FIG. 14 to the timing of the read reset signal RSR in the case of the read phase in FIG. 19C, the read phase is written. It does not pass the phase. This period T
b is determined by the tape running speed during forward high speed search playback.

Therefore, in this case, the determination as to whether the read phase exceeds the write phase can be made by the same means as shown in FIG. However, in this case,
The monostable multi-53 is triggered by the write reset signal RSW and the D-type flip-flop 54 is triggered by the read reset signal RSR.

Then, as described with reference to FIGS. 14C to 14H, the read reset signal RS during the period Tb of FIG.
When there is R, the write operation is moved from one of the memories 12A and 12B of FIG. 15 to the other at the timing of the write reset signal RSWRSR (this is the timing of the level inversion shown in FIG. 14G), and still Further, the same one line is read in the memory in which the write and read operations have been performed so far, but the read operation also shifts to the memory in which the write is started at the timing of the next read reset signal RSR. Write reset signal RS
When W and the timing of the read reset signal RSR match, the write and read operations are simultaneously transferred to the other memory.

In this way, in the embodiment shown in FIG. 14, it is possible to prevent the read phase and the write phase of the memories 12A and 12B from overtaking.

As is clear from the above description, the order /
The read / write activation circuit 47 is provided with the above-mentioned phase overtaking determination means for each reverse direction high speed search reproduction mode, and the means is switched according to the running information DI from the tape speed calculation circuit 29.

Since the speed information VI can also be obtained by monitoring the cycle of the read reset signal RSR and the write reset signal RSW, the read / write activation circuit 47 obtains the speed information VI by this. You may do it.

Further, the overtaking judgment of the writing and reading phases may be performed by the microprocessor.

Furthermore, in this embodiment, the search reproduction is explained by the reel drive system, but the capstan drive system is also used, or these two drive systems are used as in the embodiment shown in FIG. The method may be used in combination.

FIG. 20 is a block diagram showing another embodiment of the magnetic recording / reproducing apparatus according to the present invention, in which 59 and 60 are drive sources, and the portions corresponding to those in FIG. The description is omitted.

This embodiment is the same as the embodiment shown in FIG. 1, except that the capstan, the take-up reel base, and the supply reel base are driven by individual drive sources. Different from the embodiment shown in FIG. That is, in FIG. 20, the drive source 21 is a drive source dedicated to the capstan 23, and the drive sources 59 and 60 are the take-up reel stand 28 and the supply reel stand 2 respectively.
7 is a driving source.

Also in this embodiment, the same effect as that of the embodiment shown in FIG. 1 can be obtained, but since the drive source is individually used for each of the capstan 23 and the reel stands 28, 27,
Each can be controlled independently. Therefore, when shifting from the capstan drive system to the reel drive system, or vice versa, each drive source 21, such as a microprocessor, is adjusted so that the rotation speed of the capstan motor and the reel motor is adjusted to the tape running speed. By controlling 59 and 60, the drive control can be smoothly transferred without burdening the magnetic tape without mechanical switching as in the case of using a single drive source.

By the way, in each of the above-mentioned embodiments, the rotational speed of the rotary head is equal to that at the time of recording. However, this makes the vertical synchronizing frequency of the reproduced video signal always constant and secures the vertical synchronizing pull-in of the TV receiver. This is the aim. However, when the search speed is further increased,
This cannot be sufficiently dealt with only by the time axis conversion processing by the memory as in the above embodiment. For example, 10
Considering the 0 × speed high-speed search reproduction, the amount of frequency change accompanying this is approximately Δv = 0.57 from the above equation (1). Therefore, the voltage-controlled oscillator required for time-axis conversion is The oscillation frequency range of 8 is an enormous value of about ± 60%. According to this, for example, the center frequency is 20 during normal reproduction in which reproduction is performed at the same tape traveling speed as during recording.
In the case of the MHz oscillator, it is required that the frequency change up to about 32 MHz must be possible.

Therefore, as still another embodiment of the present invention, in each of the above embodiments, part of the necessary time axis conversion processing is covered by the change in the rotational speed of the rotary head. Of course, such time-axis conversion processing by changing the rotational speed of the rotary head enables vertical synchronization pull-in of the TV receiver.
%. According to this, it is possible to more effectively cope with high-speed search reproduction with a higher speed number than that of the above-described respective embodiments, and the applicable range is widened.

In this case, the structure of this embodiment is the same as that of the above embodiment, but the voltage output from the voltage generating circuit 31 is shown in FIG. In the embodiment, the value of the speed information supplied to the D / A conversion circuit 58 in FIG. 17 is only different from the case where the rotation speed of the rotary head is constant, which means that the tape speed is Arithmetic circuit 29
It can be easily realized by configuring the above with a microprocessor or the like.

[0116]

As described above, according to the present invention,
The following effects can be obtained. That is, 1) By using a very inexpensive line memory for the field memory, it is possible to realize a very fast fast-view reproduction.

2) The image does not look unnatural as if the screen was crushed.

3) It can be realized by a simple circuit without requiring calculation between scanning lines.

4) It is not necessary to change the rotational speed of the rotary head, and motor servo control is simplified.

5) It is not necessary to change the rotary head speed with the cycle data of the reproduced horizontal synchronizing signal, and there is no fear of runaway.

6) From normal reproduction to high-speed search reproduction, even if the tape driving means is changed, it can be performed by a series of one operation.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a magnetic recording / reproducing apparatus according to the present invention.

FIG. 2 is a diagram showing a specific example of the shuttle ring in FIG.

3 is a block diagram showing a specific example of a tape speed calculation circuit in FIG.

FIG. 4 is a diagram showing an example of a reel drive switching mechanism in FIG.

5 is a diagram showing a relationship between a reproduction synchronization signal and a memory write clock in the embodiment shown in FIG.

6 is a characteristic diagram showing the relationship between the frequency of the write clock of the memory and the control voltage of the voltage controlled oscillator in the embodiment shown in FIG.

7 is a characteristic diagram showing the relationship between the frequency of the write clock of the memory and the search speed in the embodiment shown in FIG.

8 is a characteristic diagram showing the control voltage with respect to the search speed of the voltage controlled oscillator in FIG. 1 that satisfies the relationships of FIGS.

9 is a characteristic diagram showing the control voltage shown in FIG. 8 separately for the output voltage of the filter and the output voltage of the voltage generation circuit in FIG.

FIG. 10 is a diagram showing a color signal processing circuit for removing an interference component from an adjacent track in the magnetic recording / reproducing apparatus.

FIG. 11 is a block diagram showing a color phase stabilizer in the magnetic recording / reproducing apparatus.

FIG. 12 is a diagram for explaining a track jump during search reproduction in the magnetic recording / reproducing apparatus.

FIG. 13 is a timing chart showing a specific example of passing of a write phase and a read phase in a memory for time-axis conversion during reverse high-speed search reproduction, and a method for preventing this.

FIG. 14 is a timing chart showing a specific example of passing of a write phase and a read phase in a memory for time-axis conversion during forward high-speed search reproduction, and a method for preventing this.

FIG. 15 is a block diagram showing another embodiment of the magnetic recording / reproducing apparatus according to the present invention.

FIG. 16 is a diagram showing conditions under which a writing phase in a memory for time-axis conversion exceeds a reading phase during reverse high-speed search reproduction.

FIG. 17 is a block diagram showing a specific example of means for detecting read phase overtaking of the write phase in the memory for time axis conversion based on the conditions shown in FIG. 16.

18 is a timing chart showing the operation of the specific example shown in FIG.

FIG. 19 is a diagram showing conditions under which a read phase in a memory for time-axis conversion exceeds a write phase during forward high-speed search reproduction.

FIG. 20 is a structural diagram showing still another embodiment of the magnetic recording / reproducing apparatus according to the present invention.

FIG. 21 is a diagram showing a scanning trajectory of the rotary head when the magnetic tape is stopped.

FIG. 22 is a diagram showing a scanning locus of the rotary head when the magnetic tape is running at a high speed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 rotary head 5 sync signal detection circuit 6 phase comparator 7 frequency dividing circuit 8 voltage controlled oscillator 9 adder 12, 12A, 12B memory 13 write control circuit 15 fixed oscillator 16 read control circuit 17 reel control circuit 18 capstan control circuit 20 shuttle ring 21 drive source 22 reel drive switching mechanism 23 capstan 24 pinch roller 25 control head 26 magnetic tape 27 supply reel stand 28 take-up reel stand 29 tape speed calculation circuit 30 recording mode discrimination circuit 31 voltage generation circuit 47 read / write Activation control circuit 48,49 Reset circuit 50 Switch 51,52 Drive source

Front page continued (72) Inventor Takeshi Kitade 292 Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa Pref., Institute of Imaging and Media Research, Hitachi, Ltd. (72) Inventor Toshio Nakamoto 1410 Inada, Katsuta-shi, Ibaraki Hitachi, Ltd. Factory AV Equipment Division

Claims (11)

[Claims] 1. A helical scan type magnetic recording / reproducing apparatus for recording in a direction oblique to a traveling direction of a magnetic tape by a rotary head, wherein a reproduced video signal is time-axis converted line by line during high speed reproduction, and A unit for deleting or adding one line as a unit to make the number of lines of the vertical synchronizing period of the reproduced video signal substantially constant, a capstan driving unit, and a driving unit for driving the driving unit. A means for transmitting a force to the reel base, a reel control means for controlling the rotation of the reel base, a capstan control means for controlling the rotation of the capstan, a reel control means and the capstan control means are selected. And a switching command means for giving a switching command to the switching means. The switching command from the switching command means is provided. Ri, as a tape drive system, the magnetic recording and reproducing apparatus is characterized in that the selectable and reel drive system and the capstan drive system. 2. A helical scan type magnetic recording / reproducing apparatus in which recording is performed in a direction oblique to the traveling direction of the magnetic tape by a rotary head, and a plurality of recording modes for traveling the magnetic tape at different speeds can be selected. A reel base drive source, a capstan drive source, means for discriminating the recording mode of the magnetic tape, and a first drive control unit for controlling the reel base drive source during reproduction according to the discriminated recording mode. Control means, second control means for controlling the drive source of the capstan according to the discriminated recording mode during reproduction, switching means for switching and selecting the first and second control means, and the switching means Switching instruction means for giving a switching instruction to the means, and a reel driving method and a capstan driving method can be selected as a tape driving method by a command from the switching instruction means. Magnetic recording and reproducing apparatus, characterized in that. 3. The switching command means according to claim 1, comprising a ring having a switch whose state changes depending on a rotation angle, and a switching command for the first and second control means depending on a rotation angle of the ring. And a magnetic recording / reproducing apparatus. 4. The magnetic recording / reproducing apparatus according to claim 3, wherein the running speed of the magnetic tape corresponding to the rotation angle of the ring is varied depending on the difference in the recording mode. 5. A helical scan type magnetic recording / reproducing apparatus for recording in a direction oblique to a traveling direction of a magnetic tape by a rotary head, and a control means for controlling a drive source for driving the magnetic tape during reproduction. A first tape speed calculating means for obtaining a traveling speed of the magnetic tape from a control signal reproduced from the magnetic tape, and a traveling speed of the magnetic tape from respective rotational speeds of the capstan, the take-up reel stand and the supply reel stand. The second tape speed calculating means and the adding means for adding the tape running speed information obtained by the first and second tape speed calculating means are provided, and the adding means includes the first and second tapes. The addition ratio of the traveling speed information obtained by the speed calculating means is made variable, and the traveling speed information output from the adding means is supplied to the control means to drive the magnetic tape to the traveling speed. Magnetic recording and reproducing apparatus, characterized in that to travel at a speed corresponding to the information. 6. A magnetic recording / reproducing apparatus according to claim 5, wherein the first and second tape speed calculating means are constituted by a microprocessor. 7. The vertical direction of the reproduced video signal according to claim 2, wherein the reproduced video signal is subjected to time-axis conversion for each line at the time of high-speed reproduction and deleted or added in units of one line. A magnetic recording / reproducing apparatus, characterized in that the number of lines of a synchronization cycle is set to a preset substantially constant number. 8. A memory means for storing a reproduced video signal for N lines (N is an integer of 1 or more and less than the number of lines for 1 field), and a write clock for the memory means according to claim 1, 2, or 5. Write clock generating means, read clock generating means for generating a read clock of a constant frequency of the memory means, and read control means for dividing the read clock to reset the read address of the memory means to a predetermined address. First frequency control means for controlling the frequency of the write clock generated by the write clock generation means in accordance with the tape speed or the tape speed command; and a sync signal detection means for detecting a sync signal of the reproduced video signal. Writing control means for resetting a writing address of the memory means to the predetermined address in synchronization with the detected synchronizing signal, Depending on the synchronizing signal, the magnetic recording and reproducing apparatus characterized in that a second frequency control means for controlling the frequency of 該書 inclusive clock 該書 inclusive clock generating means generates. 9. The write activating means according to claim 8, further comprising a write activating means for stopping the writing of the memory means in synchronization with the synchronizing signal detected by the synchronizing signal detecting means or the reset of the writing address of the memory means. A magnetic recording / reproducing apparatus characterized by the above. 10. The deletion video signal according to claim 1, 2 or 5, wherein the reproduction video signal is divided into N lines (N is an integer of 1 or more and less than 1 field line number) in order to perform deletion or addition on the time axis. ) First and second memory means for storing, write clock generating means for generating write clocks for the first and second memory means, and read clocks of constant frequency for the first and second memories Read clock generating means, read control means for dividing the read clock and resetting the read addresses of the first and second memories to predetermined addresses, and the write operation in response to the tape speed or the tape speed command. First frequency control means for controlling the frequency of the write clock generated from the clock generation means, and synchronization signal detection means for detecting the synchronization signal of the reproduced video signal, Write control means for resetting the write address of the first and second memory means to the predetermined address in synchronization with the sync signal, and generation from the write clock generation means in response to the detected sync signal Second frequency control means for controlling the frequency of the write clock, and writing to the first and second memory means in synchronization with the detected synchronizing signal by the read control means. , Second
Read / write activation control means for activating and deactivating the reading from the first and second memory means in synchronization with the reset of the read address of the memory. Magnetic recording / reproducing device. 11. The magnetic recording / reproducing apparatus according to claim 8, wherein the first frequency control means is composed of a microprocessor that converts tape speed information into a control signal.