JPS6038777A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To prevent a blank part from being generated on a tape when the second signal is recorded in an insertion recording mode, by controlling non-operations of an erasing head and a rotary recording head with a counter 9 which counts the prescribed length of the tape. CONSTITUTION:The running length of the tape after the insertion recording start due to a rotary head 6 is detected by a rotation detector 7, and contents of the counter 9 which is set to a prescribed value are counted down through a detection signal amplifier 8. When the count value of the counter 9 becomes 0, the operation of a full-width erasing head is stopped through a full-width erasing head operating circuit 11 by a control circuit 10. Next, counting of the counter 9 is switched to up-counting; and when the count value reaches a prescribed set value, a rotary magnetic head operating circuit 12 is controlled by the circuit 10, and the recording operation due to the head 6 is stopped. As the result, the blank part where no signals are recorded is not generated on the tape when the second signal is recorded in the insertion recording mode, and a reproduced video signal is prevented from being bad.

Description

[Detailed Description of the Invention] Technique 14/i Field> The present invention relates to a magnetic recording/reproducing device, and in particular, to a magnetic recording/reproducing device that controls the operating state of a magnetic head according to the output of a counter that counts the running length of a magnetic tape. Regarding things.

<Prior art> A first video signal (referred to as a first signal) is generated using a magnetic recording/reproducing device, for example, a VTR (video tape recorder).
A second video signal (referred to as a second signal) may be recorded on a portion of a magnetic tape on which a second video signal has already been recorded. In such a case, the conventional VTR records the second signal on the magnetic tape as follows.

First, the VTR is set to the interleaved recording mode for the second signal.

In this mode, a magnetic tape on which a first signal is recorded is run, a part of the first signal on the magnetic tape is erased by a full-width erase head, and a second signal is transferred to the erased portion by a rotating magnetic field. It is inserted and recorded by the head.

- After this recording, both the full-width erase head and the rotating magnetic head become inactive, and the insertion recording mode ends.

Incidentally, in a VTR, a full-width erasing head and a rotating magnetic head are arranged at a predetermined interval. Therefore, the first signal is erased by the full-width erasing head at a predetermined interval between the full-width erasing head and the rotating magnetic head on the magnetic tape.

On the other hand, the rotating magnetic head is placed at a position where signals cannot be recorded in this portion. Therefore, this predetermined interval portion becomes a blank (non-recorded) portion where no signal is recorded. Therefore, when a magnetic tape with such blank areas is run during playback and a playback screen is displayed on a CRT, the resulting reproduced image becomes unsightly due to the blank areas, causing discomfort to the viewer. Sometimes.

<Purpose> An object of the present invention is to prevent the above-mentioned blank area from occurring when a second signal is recorded in the insertion recording mode, and to make the reproduced image easier to see.

<Example> Hereinafter, the present invention will be described in detail based on an example shown in the drawings.

FIG. 1 shows the magnetic equipment of a VTR to which this embodiment is applied, where 1 is a supply reel, 2 is a take-up reel, 3 is a magnetic tape,
4 is a magnetic tape drive unit, 5 is a fixed full-width erase head, 6 is a magnetic tape drive unit;
is a rotating magnetic head that is attached to both ends of a head par 15 within a tea cylinder-shaped cylinder 14 and is exposed to the outside through a slit in the cylinder 14. Magnetic tape 3 is supply reel 1
The winding is carried out through the guide rollers 16 on one side so as to be wound around the cylinder 14 in an Ω-shape and obliquely, and the winding is carried out through the guide rollers 17 on the other side.
2. 7 is a rotation detector for detecting the running length of the magnetic tape 3; 8 is a detection signal amplifier for amplifying the detection signal from the rotation detector 7; 9 is a counting operation in response to the detection signal from the detection signal amplifier 8. 10 is a control circuit that generates a control signal, which will be described later, in response to the count output from the counter 9;
12 is a full-width erase head operating circuit that drives the full-width erase head 5 in response to an erase head drive control signal from the control circuit 10; -'6 is a rotating magnetic spatula 1q operation circuit; 13 is a servo control unit that servo-controls the rotational speed of a DC motor in the magnetic tape running system in response to the output from the detection signal amplifier 8;

The magnetic tape drive unit 4 includes a flywheel 4a rotated by the DC motor, and a capstan 4b that rotates integrally with the flywheel 4a to run the magnetic tape 3.
, a pinch roller 4C for pressing the magnetic tape 3 against the capstan 4b, and a DC motor 4d for rotating the flywheel 4a.

The rotation detector 7 includes a light emitting section 7a that emits light to the flywheel 4a, and a light emitting section 7a that emits light from the flywheel 4a.
and a detection signal forming section 7 (that forms a detection signal corresponding to the rotational speed of the flywheel 4a based on the light received by the light receiving section 7b).

The magnetic tape drive section 4 is set to a mode for rewinding and reproducing the magnetic tape 3 during the insertion recording mode, that is, when recording the second signal on the magnetic tape 3 on which the first signal has been recorded. While the magnetic tape 3 is being rewound and played back,
It is checked whether the magnetic tape 3 has been run to a point where the operator wants to insert the second signal and start recording.

This confirmation causes the magnetic tape 3 to stop running when it has been rewound to the point where the second signal is inserted and recorded. When the magnetic tape 3 is stopped in this way, the push-in recording mode command signal is transmitted to the VTR.
is given to enter insert recording mode. At this time, a counter value corresponding to the tape running length by which the tape has been returned by rewinding and playback is stored in memory.

Next, insertion recording of the second signal in the insertion recording mode will be explained with reference to FIG. First, in FIG. 2, arrow 18 represents the direction in which the magnetic tape 3 travels. T1
T2 is a period set for adjusting the phase of each signal from the insertion recording mode command as described later (the operation mode of the VTR during this period is set to phase adjustment mode), and T2 is the period during which the second signal is inserted and recorded. This is the insertion recording period. This insertion recording period T2 is a period T2+ when both the full-width erase head 5 and the rotary magnetic head 6 are driven, and the period T2+ when the full-width erase head 5 and the rotary magnetic head 6 are driven.
There is a period T22 in which the rotary magnetic head 6 is in a non-operating state and the rotary magnetic head 6 is in a driving state. In addition, (1 is the start time of period T21,
[2 is the period T2+ during which the counter 9 output becomes the first predetermined value
and the start time of the period T22, L3 is the same (the end time of the period T22 when the output of the counter 9 reaches the second predetermined value, and the time when the magnetic tape 3 stops running).

Next, the control of the full-width erase head 5 and the rotating magnetic head 6 in the insertion recording mode performed by the system centered on the control circuit 10 will be explained.

First, in order to record the second signal on the magnetic tape 3, the rotational speed of the flywheel 4a, that is, the running length of the magnetic tape 3 is detected by the rotation detector 7.

The detection signal output from the rotation detector 7 is amplified by the detection signal amplifier 8 and then sent to the counter 9 and the servo controller 13.
given to. The counter 9 starts the count subtraction operation at the same time as the time [1: insertion recording mode starts] after the end of the phase adjustment mode period TI, which will be described later. This period T
2, the counter 9 is greater than or equal to the first predetermined value during the period T21, so the control circuit 10 controls both head operation circuits 1!1.
A head drive control signal is given to 2. As a result, both heads 56 are driven, and the second signal is recorded in the same way as normal signal recording. This period T21 passes. Time [2
Then, a period T22 is entered in which the output of the counter 9 reaches the first predetermined value. Then, the control circuit 10 continues to supply the head drive control signal to the rotary magnetic head operation circuit 12 to operate the rotary magnetic head 6, but the full-width erase head operation circuit 11 receives full-width erase head drive control. Stop signal output. As a result, the rotating magnetic head 6 is in a driven state, but the full width erase head 5 is in an inactive state. After the period T22 has elapsed and the count value of the counter 9 reaches the second predetermined value at time L3, the control circuit 10 outputs a rotary magnetic head control signal to the rotary magnetic head operating circuit 12 at the end time of the signal insertion mode. stop. As a result, the rotating magnetic head operating circuit 12 puts the rotating magnetic head 6 into a non-operating state. This causes recording of the second signal to stop. Since the magnetic tape 3 is made to travel a predetermined length between times L3 and [2], at time t2, the part of the magnetic tape 3 that was in contact with the full-width erase head 5 just reaches the rotating magnetic head 6 at time [3]. reach. In other words, the portion of the magnetic tape 3 where erasure of the first signal was stopped at time [2] and the portion where insertion of the second signal was stopped at time [3] are the same location.

Therefore, the portion of the magnetic tape 3 where erasing of the first signal is stopped and the portion where recording of the second signal is stopped coincide with each other, and it is possible to prevent blank (also recorded) portions from occurring.

FIG. 3 shows a specific turn i1 of the servo control unit 13 shown in FIG.
．． ! '1 figure. Here, the servo control section 1 shown in FIG.
Before explaining Section 3, insertion recording of the second signal by a conventional VTR will be briefly explained. That is, in the conventional VTR,
The insertion recording of the second signal is performed at a timing that is temporally unrelated to the first signal.

Therefore, since the insertion recording start portion of the second signal on the magnetic tape 3 is the boundary between the first and second signals, the interval between the vertical synchronizing signals is not constant. Therefore, during playback, vertical synchronization signals with different timings are emitted from these parts, resulting in a distorted image being displayed. This servo control unit 13 is provided to prevent a distorted image from being displayed on the reproducing device even if the signal at the start of the insertion recording mode is reproduced.

Next, the configuration of the servo control section 13 shown in FIG. 3 will be explained. A is the detection signal S1 given by the detection signal amplifier 8
The speed control section-B generates a signal for making the rotation of the DC motor 4d constant in accordance with the rotation speed of the magnetic tape 3, and supplies rotational power to the DC motor 4d for running the magnetic tape 3. A motor drive circuit that controls the rotational speed of the DC motor 4d according to the signal given from the sample hold section ①, where C is the detector 3S given from the detection signal amplifier 8, is frequency-divided, and the result is converted into a frequency-divided signal. This is a frequency divider that outputs as follows. Note that the frequency dividing section C receives a control signal S via a fourth switch SW4, which will be described later.
It is reset when 5 is given. 4th switch SW
4 is opened and the supply of the control signal S5 is stopped, it starts outputting the frequency-divided signal in the same timing relationship as the applied control signal S5. D records the applied vertical synchronization signal as a control pulse on the side edge of the magnetic tape 3 during recording and insertion recording modes, and reads recontrol pulses from the magnetic tape 3 during playback and phase adjustment modes. The control head E that outputs a control signal is a control signal amplifying section that amplifies the control signal S3 given from the control head D.

F is a vertical synchronizing signal section connected to a vertical synchronizing signal separation circuit (not shown), which supplies a vertical synchronizing signal separated from the television radio waves being input to the VTR; G is a vertical synchronizing signal section having the same waveform as the vertical synchronizing signal S4; This is a reference signal generating section that generates a reference signal S5. H is a trapezoidal wave generator that converts the applied signal into a trapezoidal wave S6 and outputs it, and ■ is a trapezoidal wave generator that samples the trapezoidal wave S6 provided by the trapezoidal wave generator H using a signal provided via the first switch SWI, which will be described later. This is a sampling hold section. The sampling hold section (2) provides the motor drive circuit A with a sampling signal indicating the result of sampling. SW1 is a first switch that connects one of the individual contacts Co to the frequency divider section C, the other individual contact CI2 to the control signal amplification section G, and the movable contact CI3 to the sample hold section (2).

In the first switch SW1, in each of the recording and insertion modes, the movable contact C13 is connected to the individual contact C11, and the frequency divided signal S2 output from the frequency dividing section C is applied to the sample and hold section (2). Further, in each of the reproduction and phase adjustment modes, the movable contact CI3 is connected to the individual contact CI2, and the control signal S5 output from the control signal amplification section E is applied to the sample hold section I. SW
2 connects one of the individual contacts C21 to the third switch SW3.
This is a second switch that connects the other individual contact C22 to the control signal amplifying section E and the movable contact C23 to the control head D, respectively. 2nd switch SW2
The movable contact C23 is connected to the individual contact C2+ during each of the recording and insertion recording modes, and by this connection, the vertical synchronizing signal S4 output from the vertical synchronizing signal section F is applied to the control head D. During the playback and phase adjustment modes, the movable contact C23 of the second switch SW2 is connected to the individual contact Q2, thereby controlling the control head D.
A control signal S3 outputted from the control signal amplifying section E is given to the control signal amplifying section E.

One of the individual contacts C31 of SW3 is the vertical synchronization signal section F.
Then, the other individual contact C32 connects the movable contact C23 to the reference signal generator G, and the movable contact C23 connects to the trapezoidal wave generator I and the second switch S.
This is a third switch connected to each individual contact C2 of W2. The movable contact C33 of the third switch SW3 is an individual contact C33 in each mode of recording, insertion recording, and phase adjustment.
31. At this time, the vertical synchronizing signal S4 from the vertical synchronizing signal section F is applied to the trapezoidal wave generating section I and the individual contact C2+ of the second switch SW2.

In the regeneration mode, the movable contact C3 of the third switch SW3
3 is connected to the individual contact C32. At this time, the reference signal S5 output from the reference signal generator G is output from the trapezoidal wave generator I.
given to. SW4 is a normally open fourth switch connected to the frequency dividing section C and the control signal amplifying section F. This fourth switch SW4 is closed only in the phase adjustment mode, and the control signal S5 output from the control signal amplifying section E is applied to the frequency dividing section C.

The motor drive circuit B gives constant speed to the rotation of the DC motor 4d by the signal given from the speed control part A, and controls the rotational speed of the DC motor 4d more precisely by the sampling signal given from the sampling hold part (■). Add phase control. In addition, the control head D is
The rotating magnetic spatula l' 6 (!: ml) is arranged so that the running length of the magnetic tape 3 between it and the control head D is an integral multiple of the interval between control pulses. The control signal can be written and read at the same timing as the vertical synchronization signal written and read by 6.

Next, the operation of the servo control section 13 when switching from the phase adjustment mode to the insertion recording mode will be explained.

In the phase adjustment mode, the trapezoidal wave generating section H converts the vertical synchronizing signal S4 provided from the vertical synchronizing signal section F via the third switch SW3 into a trapezoidal wave s6. Also, the control signal S3 given by the control head D is given to the sample and hold section (2) via the control signal amplifying section E and the first switch SW1. In the sample hold section I, the trapezoidal wave S6 from the trapezoidal wave generator H is sampled in accordance with the control signal S3. The motor drive circuit B is controlled by the sampling signal S7 indicating the result. The running speed of the magnetic tape 3 is controlled so that the vertical synchronization signal S4 and the control signal S3 coincide in timing. Therefore, by this control, the timings of both signals completely match after a certain period of time has elapsed. Further, the fourth switch SW4 is closed and the control signal S3 is applied to the frequency dividing section C. This resets the frequency dividing section C. After a certain period of time has elapsed since the start of phase adjustment mode, the mode changes to insertion recording mode. Fourth
Switch SW4 is pressed and branch C is released from reset.

The frequency dividing section C starts outputting the frequency divided signal S2 in the same timing relationship as the control signal S3 in the phase adjustment mode. The sample hold section I converts the trapezoidal wave S6 into the frequency-divided signal S2.
, and generates a sampling signal S7.

Therefore, the rotational speed of the DC motor 4d does not suddenly change when switching from the phase adjustment mode to the insertion recording mode. Further, a vertical synchronizing signal S4 outputted via the third switch SW3 is recorded on the magnetic tape 3 by the control head D. In the phase adjustment mode, the vertical synchronizing signal S4 and the control signal S3 obtained by reading the control pulse of the first signal of the magnetic tape 3 are controlled so that they have the same timing relationship. Therefore, at the start of the insertion recording mode, the vertical synchronizing signal S4 of the second signal is recorded on the magnetic tape 3 in a common phase relationship with the control pulse of the first signal. Since the control pulse and the vertical synchronization signal S4 are recorded on the magnetic tape 3 with a common timing relationship, the vertical synchronization signals of both the first and second signals are also recorded with a common timing relationship. Therefore, when the recorded signal is reproduced in row 9, vertical synchronization will not be lost at the beginning of insertion of the second signal.

<Effects> As described above, according to the present invention, the first signal is recorded in a magnetic recording/reproducing apparatus in which an erasing head and a recording head are arranged at a predetermined interval along the running direction of a magnetic tape. means for inserting and recording a second signal on the magnetic tape via the recording head; a counter for counting the recording length of the second signal inserted by the former recording means; The erase head is driven until the output reaches the first predetermined value, and after the output reaches the first predetermined value until it reaches the second predetermined value at the end of insertion of the second signal. Since the erasing head is configured by a control circuit that controls the erasing head to be in an inoperable state, it is possible to prevent a blank unrecorded state between the insertion recording part of the second signal and the recording part of the first signal of the magnetic tape. I can do it. This makes it possible to make the reproduced image of the magnetic tape easier to see.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a block diagram showing a magnetic tape running system, FIG. 2 is a schematic diagram showing a state of insertion and recording of a second signal on the magnetic tape, and FIG. 3 is a servo FIG. 2 is a block diagram showing a control system. 5... Full-width erase head 6... Rotating magnetic head 9.
... Counter 10 ... Control circuit applicant Sharp Corporation agent Patent attorney Kazuhide Okada

Claims (1)

[Claims] (1) In a magnetic recording/reproducing device in which an erasing head and a recording gutter are arranged at a predetermined interval along the running direction of the magnetic tape, the recording is performed on the magnetic tape on which the first signal is recorded. means for inserting and recording a second signal through a slot; a counter for counting the insertion recording length of the second signal by the recording means; The erase throat is driven until the first predetermined value is reached, and after the first predetermined value is reached, the second
a circuit for controlling the erasing head to be inactive until a second predetermined value is reached at the end of insertion of the signal.