JPS62118683A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To prevent the disturbance of a pattern by using the 1st control signal and a signal obtained by the phase comparison of a reference signal as a variable speed reproduction. CONSTITUTION:When a variable speed reproduction command signal SH from a terminal 21 is inputted to a head control circuit 18, a rotary head pair 10 of the normal reproduction is changed over into a rotary head pair 11 exclusive for variable speed reproduction, a switch 17 is switched from a contact (a) to (b) and a reproduced video signal is extracted. Since a head switching control signal RF1 is fed to a trapezoidal wave generation circuit 15 even at the variable speed reproduction, the head servo system comprised of circuits 15, 16, 19 is controlled by the same signal at the normal reproduction. Since the relation of phase between head switching control signals RF1, RF2 is constant and no phase comparison is required, a phase error signal CV1 of the head servo system at the transition has no change, the head servo is made stable and no disturbance due to the changeover is caused as the head rotation.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a helical scan type magnetic recording and reproducing device having a first pair of rotary heads for normal reproduction and a second pair of rotary heads for variable speed reproduction. In particular, when switching from the first rotating head pair to the second rotating head pair when transitioning from normal playback to variable speed playback, it prevents disturbances in the reproduced image caused by sudden changes in the control voltage of the rotating head surf system. Regarding equipment.

[Prior Art] In this type of magnetic recording and reproducing device, for example, a video tape recorder (VTR), during variable speed playback, a second rotating head used during variable speed playback is rotated from a first rotating head used during normal playback to a second rotating head used during variable speed playback. In order to prevent sudden changes in the control voltage of the servo system of the rotating head when switching between pairs, for example, in Japanese Patent Application Laid-Open No. 60-55777, a PC signal is used as a control signal for normal playback and variable speed playback. creating a first control signal and a second control signal, respectively, and creating a first reference signal synchronized with the first control signal and a second reference signal synchronized with the second control signal, each first
．． A second control voltage is obtained. In the transition from normal playback to variable speed playback, a changeover switch is used to shift from the first control voltage to the second control voltage without any sudden change, thereby eliminating disturbances in the reproduced image.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional technology, the control signal SPI during normal playback and the control signal SP2 during variable speed playback are used separately as control signals for the servo system of the rotating head. Therefore, in order to prevent sudden changes in the servo voltage, it is necessary to generate two types of reference signals, RP1 and RP2, to determine the phase of the head, which complicates the circuit configuration and causes screen disturbances when switching to variable speed playback. There were some problems, such as not being able to completely prevent this.

Therefore, this invention prevents sudden changes in the servo voltage even when switching between normal playback and variable speed playback.
Therefore, it is an object of the present invention to provide a magnetic recording/reproducing device that has a simple configuration that does not require changing the reference signal in response to sudden changes in the servo control signal as in the past, and that can effectively prevent screen disturbances. .

[Means for Solving the Problems] In order to achieve the above-mentioned object, the magnetic recording and reproducing apparatus of the present invention rotates a first pair of rotary heads for normal reproduction and a second pair of rotary heads for variable speed reproduction. It has a rotating head structure attached to a rotating body at mutually different angles in the direction, and when the pair of rotating heads rotates, the first and second pairs of rotating heads representing the rotational phases of the first pair of rotating heads and the second pair of rotating heads are rotated. In a helical scan type magnetic recording and reproducing apparatus, the rotation phase of the rotary head pairs is synchronized with the reference signal by obtaining a second control signal and generating a reference signal corresponding to the control signal for each of the rotary head pairs. The first control signal is applied to the video system during normal playback, and the second control signal is applied during variable speed playback, while the signal supplied to the rotary rad servo system is applied during normal playback and variable speed playback. In some cases, a signal obtained by phase comparison of the first control signal and the reference signal and a signal obtained by phase comparison of the reference signal are used.

[Embodiment] FIG. 1 is a block diagram showing an embodiment of the JJ cal scan type VTR according to the present invention, in which I represents a magnetic tape;
2 is a capstan motor, 3 is a capstan control circuit,
4 is a sample hold circuit, and 5 is a trapezoidal wave generating circuit. 7 is a control signal detector that detects the control signal on the magnetic tape; 6 is a control signal amplifier; the trapezoidal wave generating circuit 5 and the sample hold circuit 4 constitute a phase comparator; The signals and phases are compared, and the output of the capstan control circuit 3 is controlled based on the comparison result to control the speed of the capstan motor 2 and the running of the magnetic tape 1.

8 is a rotary head drum around which the magnetic tape 1 is wound within a predetermined angle range, and this head drum 8 is rotatably provided with a first pair of heads 10 for normal playback and a second pair of heads 11 for variable speed playback. It is being 1st head vs. 10 and 2nd
The pair of heads 11 is provided with a predetermined chromaticity O of 1 bit to compensate for changes in the anomalous angle due to changes in tape speed.

9 is a head motor that rotates the head pair 10 and II. A first pair of heads 1O reproduces video signals from a magnetic tape 1 running at normal speed, and a second pair of heads II reproduces video signals during variable speed reproduction.

3 heads vs. 10. The phase of II is detected by the rotational phase detector 12 and represents the rotational phase of the head (the signal is sent to the amplifier 13
A signal PG is obtained by amplifying the signal.

The PC signal is input to the head control signal generation circuit 14, and the P
Rectangular wave RF1 with G times signal delay. Get RF2. Head switching control signals RFI and RF'2 are used for rotating head pairs IO and 1.
They are each synchronized with the rotational phase of 1.

17 is a head control signal changeover switch which can be switched depending on whether it is normal playback or variable speed playback, terminal a which is turned on during normal playback receives the head changeover control signal RFI, while terminal a which is turned on during variable speed playback is head switching control signal rj
Take F2. A signal obtained from terminal C of this changeover switch I7 is applied to a head control circuit 18 that controls which head pair is selected.

Head switching control signal RF of head control signal generation circuit 14
The output terminal of 1 is connected to the trapezoidal wave generating circuit +51.

The output signal TR1 of the trapezoidal wave generation circuit 15 is applied to the sample bold circuit 16, and the output of the sample hold circuit 16 is applied to the head drum control circuit 1 that controls the head motor.
9, and these three circuits 15, 16 and 19
These constitute a rotational phase servo control system that servo-controls the rotational phase of the head pair 10 and 11.

As mentioned above, the head switching control signal RFI is activated by the switch 17.
Since the signal is input to the trapezoidal wave generating circuit 15 regardless of the switching position of the signal RF'1, the servo control of the head, normal playback, and variable speed playback are all performed by one signal RF'l.

20 is composed of circuit 3.4.5 (two-phase control system and circuit + 5.16.19 is composed of
This is a reference signal generation circuit that provides an Un pulse SPI to each of the control σ1j systems.

FIG. 2 is a waveform diagram showing each signal in the main part of the circuit of FIG. 1. Next, the operation shown in FIG. 1 will be explained with reference to FIG. 2.

First, normal playback will be explained. At this time, head vs. 1
0 allows the video signal to be played back. On the other hand, a detection signal (PC signal) representing the head rotation phase detected by the counterclockwise phase detector 12 is amplified by the amplifier 13 to obtain a signal PG. PG double signal head control signal generation circuit 1
Rectangular waves RFl and RF input to 4 and delayed from the P and G signals
Get 2. The head switching control signals RPI and RF2 are synchronized with the rotational phase of the rotating head pair 10 and 11, respectively.

During normal playback, the switch 17 is connected to terminal a, and the head switching control signal RFI is input to the head control circuit 18. 2 that constitutes the pair lO
A continuous video signal is obtained by alternately switching the playback output from the two heads. Also, the head switching control signal R
FI is input to the trapezoidal wave generation circuit 15, and a trapezoidal wave signal TRI is obtained which increases in a trapezoidal manner in synchronization with the rising edge of the signal RFl.Furthermore, the reference signal generation circuit 20 outputs the reference signal SPI, which is a trapezoidal wave signal TRI. The reference signal SPi is supplied to a sample-and-hold circuit 16 to obtain a phase error signal CVI representing the phase difference between the trapezoidal wave signal TRl and the reference signal SP[. On the other hand, the cab scan phase control system, like the head drum phase control system, obtains a phase error signal CV2 to control the running speed of the magnetic tape I.

Now, when the variable speed playback command signal SH is manually inputted from the terminal 2I to the head control circuit I8, the output of the head control circuit I8 causes the first pair of rotary heads 10 to move from the second pair of rotary heads 11 exclusively for variable speed reproduction. Switch to. On the other hand, the contact of the switch I7 is switched from a to b, and the two heads forming the head pair 11 are switched to the positive/negative half cycle f+j of the head switching control signal RF2, and the 1 f raw Hideoi No. 11 is removed. be done.

During this variable speed bi-directional operation, the steering wheel switching control signal IN'
Since l is applied to the trapezoidal wave generating circuit I5, the circuit +5
．． The belly button servo system by IG, I9 should be controlled by the same signal as during normal playback. By the way, regarding the servo system, the head switching control signals flFI and It'2
has a constant phase relationship with /b, the head switching control signal (
(There is no need to compare the phase at F2.

Therefore, there is no change in the phase error signal 5ycv+ of the Hesodosar water system when changing from normal 111 playback to variable speed playback.
The head motor is stable, and there is no disturbance in the rotation of the belly button due to the above switching. Therefore, there is little disturbance in the reproduced image when switching between normal speed reproduction and variable speed reproduction.

[Effects of the Invention] As described above in detail, according to the present invention, video signals can be taken out in a helical force Gyan magnetic recording/reproducing apparatus I" which is equipped with a rotary head for variable speed reproduction of 6:2. During normal playback, the first control signal Ill is used to represent the rotational position tll of the first pair of rotary heads, and during variable speed playback, the second control signal RF'2 is used to represent the rotational phase of the second pair of rotary heads. As for the hesodon servo system, the first control signal RF' is used both during normal playback and during variable speed playback.
Since phase control is performed using l and base signal SPI, there is no change in the phase error signal during transition from normal playback to variable speed playback, the head motor is stable, and there is no disturbance in the playback screen.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a waveform diagram of the main part of the circuit shown in FIG. ■...Magnetic tape, 8...Head drum, 9...
・Head motor, IO・・Normal playback head pair (first head pair), II・
...Head pair for variable speed playback (second head pair), 14.
...Head control signal generation circuit, 15.. Trapezoidal wave generation circuit, 16.. Zabur hold circuit, 19.. Head drum control circuit, 20.. Group f4a signal generation circuit, r? F+ ・First control signal, SPI ・Block signal.

Claims (1)

[Claims] (1) It has a rotary head structure in which a first pair of rotary heads for normal reproduction and a second pair of rotary heads for variable speed reproduction are attached to a rotating body at different angles in the rotational direction, and the pair of rotary heads By rotating, first and second control signals representing the rotational phases of the first pair of rotary heads and the second pair of rotary heads are obtained, and a reference signal corresponding to the control signal of each pair of rotary heads is generated. In a helical scan type magnetic recording and reproducing device in which the rotational phase of a pair of rotary heads is synchronized with a reference signal, the first control signal is applied to the video system during normal playback, and variable speed playback is performed. While the second control signal is sometimes applied, the signal supplied to the rotary head servo system is a signal obtained by phase comparison of the first control signal and the reference signal and the reference signal during normal playback and variable speed playback. A magnetic recording/reproducing device characterized in that it uses a signal obtained by phase comparison.