JPS62167652A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To attain an accurate assemble edition by using a phase comparison means generating an error voltage representing a phase difference between a reference signal and a comparison signal and a means controlling a motor in response to the error voltage so as to apply phase lock between the reference signal and the comparison signal. CONSTITUTION:When a mode switching signal E reaches an L level at a point b', switches 8, 17 are switched to the position (a), a capstan servo is selected to the recording mode, the reference signal A is amplified by an amplifier circuit 18 and a magnetic tape 1 is recorded by a control head 4. Further, an internal reference signal C is inputted as the input signal F of a trapezoidal wave generating circuit 9 to form a trapezoidal wave G. Further, a frequency- division output I is given as a comparison signal J, a sampling signal K is outputted to sample the trapezoidal wave G at the leading edge. The delay amount T2 is decided so that the phase relation between a delay signal at the reproduction mode and a reproducing control signal H is the same as the phase relation between the internal reference signal C in the recording mode and the frequency division output I. Thus, the accurate assemble edition is attained with a simple circuit constitution.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention is a magnetic tape that enables assembly editing without causing capstan servo disturbance when newly recording a video signal on a video signal recorded on a magnetic tape. The present invention relates to a recording/reproducing device.

Conventional technology In a magnetic recording/reproducing device (hereinafter referred to as VTR), when a new video signal is continuously inserted and recorded on a video signal recorded on a magnetic tape, during the transition period from the playback mode to the recording mode, the cap The phase lock of the stun servo is disturbed,
A phase shift occurs between the control signal already recorded on the magnetic tape and the newly recorded control signal.
Correct assemble editing is not performed.

Therefore, phase control is performed between the period reference signal in the reproduction mode and the control signal reproduced from the magnetic tape, and the frequency of the period reference signal in the recording mode and the frequency generator (hereinafter referred to as FG) of the capstan motor is divided. In conventional VTRs that perform phase control with the circuit output, the FGO frequency divider circuit is reset by the control signal during playback mode to maintain the phase lock state, and the frequency divider circuit is reset when switching to record mode. By canceling this, continuity between the control signal and the frequency divider circuit output is maintained, allowing accurate assemble editing.

An example of the conventional capstan servo mentioned above will be described below with reference to the drawings.

FIG. 3 is a block diagram of a conventional capstan servo, and FIG. 4 shows its timing. In Figure 3, 1 is the magnetic tape, 2 is the capstan motor, 3 is the control signal, 4U control head, 5 is the FG, 9
1 is a trapezoidal wave generating circuit, 1o is a sample/hold circuit (hereinafter referred to as S/H circuit), 16 is a frequency dividing circuit, 1 is a reference signal, and 2 is a mode switching signal.

The operation of the conventional capstan servo configured as described above will be described below.

In the reproduction mode, the mode switching signal E is at H level, and the switches 8 and 16 are connected to the b side. The reference signal is a reference signal for the capstan servo, and is usually a 30 Hz square wave generated from a video signal to be recorded, as shown in FIG. The reference signal is delayed by a delay circuit 13, and tracking adjustment is performed by changing the delay amount T) by a variable resistor 12.

The delayed signal B is supplied to the trapezoidal wave generating circuit 9, and a trapezoidal wave G is formed at the falling edge. The trapezoidal wave 0 is sampled by the sampling signal K in the S/H circuit 10, controls the drive circuit 11, drives the capstan motor 2, and runs the magnetic tape 1. magnetic tape 1
The control signal 3 recorded in the control head 4
The reproduction control signal H is obtained by the amplifier circuit 17 through the switch 16, and is supplied to the delay circuit 14 through the switch 8. The trapezoidal wave G is sampled at the rising edge of the sampling signal having a delay amount T2.

Through the series of operations described above, the capstan motor 2 is controlled, and the reference signal and the reproduction control signal H are brought into a phase-locked synchronous state.

Furthermore, in order to maintain the phase lock of the capstan servo when editing the complete sample, the frequency dividing circuit 16 is reset with the playback control signal H during the playback mode to obtain the frequency division ratio, and it is switched using the mode switching signal E. The continuity of the comparison signal J is maintained during the transition period from the reproduction mode to the recording mode.

When the mode switching signal E changes to the L level at point a', the switches 8 and 16 are switched to the a side, and the capstan servo enters the recording mode.The reference signal is amplified by the amplifier circuit 18 and recorded from the control head 4 to the magnetic tape 1. be done.

Since the reproduction control signal H and the basic signal are kept in phase-lock synchronization in the reproduction mode and the recording mode, the continuity of the control signal 3 is maintained. Furthermore, in the recording mode, the reset of the frequency divider circuit 16 is released, and the frequency division ratio becomes a sampling signal that is at the L level for a period of delay amount T2 in the delay circuit 14. Since the trapezoidal wave G is sampled at the rising edge, the comparison signal J and With the trapezoidal wave G, the phase lock synchronization state is maintained in the reproduction mode and the recording mode, so no disturbance of the capstan motor occurs.

Accurate assemble editing can be achieved through the above series of operations.

Problems to be Solved by the Invention However, in the above configuration, a VT of a format in which the control signal 3 does not exist (for example, 8m/mVTR)
In R, the continuity of the comparison signal J cannot be guaranteed, so accurate assembly editing cannot be guaranteed.

The present invention provides a magnetic recording/reproducing apparatus that enables accurate assembling/editing even in a format in which the control signal 3 does not exist.

Means for Solving the Problems In order to solve the above-mentioned problems, the magnetic recording and reproducing apparatus of the present invention includes a tape feeding means for running a magnetic tape at a predetermined speed, and a tape capstan for driving the magnetic tape. a frequency generator that generates electrical pulses representing the speed of the motor in response to the rotation of the motor; a first frequency divider circuit that divides a pulse train of a predetermined frequency to generate a reference signal; a second frequency dividing circuit that obtains a comparison signal having the same frequency as the reference signal from the electric pulse obtained from the magnetic tape at a predetermined speed of the magnetic tape, and controlling the first frequency dividing circuit with the reproduction operation period comparison signal; The reference signal and the comparison signal are phase-locked, and the transition period from the reproduction operation to the recording operation, the first
The reference signal and the comparison signal are phase-locked by a phase comparison means that releases the control of the frequency dividing circuit and generates an error voltage representing the phase difference between the reference signal and the comparison signal, and a means that controls the motor according to the error voltage. It is equipped with a configuration that allows

According to the present invention, the reference signal is controlled by the comparison signal obtained by dividing the frequency of the FG of the capstan motor during the playback operation period with the above-described configuration, and the phase difference is controlled, so that the reference signal after the transition to the recording operation is When control is released, the reference signal and comparison signal are phase-compared and the capstan motor is controlled so as to achieve phase lock. By setting the reference signal and comparison signal to have the same phase relationship in the reproducing operation and the recording operation, accurate assemble editing without phase holes becomes possible.

EXAMPLES Hereinafter, examples of the present invention will be described with reference to the drawings.

Figure 1 is a block diagram of the capstan servo, and Figure 2 is a block diagram of the capstan servo.
The figure shows the timing.

In Figure 1, 1 is a magnetic tape, 2 is a capstan motor,
3 is control (l, 4 is control head, 5 is FC, 6 is oscillation circuit, 7 is frequency dividing circuit, 9 is trapezoidal wave generation circuit, 1o is S/H circuit, 16 is frequency dividing circuit, person is reference The signal E is a mode switching signal.

The operation of the capstan servo in this embodiment configured as described above will be explained below with reference to FIGS. 1 and 2.

In the reproduction mode, the mode switching signal E is at H level, and the switches 8 and 16 are connected to the b side. The reference signal is a reference signal for the capstan servo, and is usually a 30H2 square wave made from a video signal to be recorded, as shown in FIG.

The reference signal is delayed by a delay circuit 13 and connected to a variable resistor 12.
Tracking adjustment is performed by changing the delay amount T1. The delayed signal B is supplied to the trapezoidal wave generating circuit 9, and a trapezoidal wave G is formed at the falling edge. The trapezoidal wave G is sampled by the S/H circuit 1o using the sampling signal K, and the magnetic tape 1 is caused to run by controlling the drive circuit 11 and driving the capstan motor 2. The control signal 3 recorded on the magnetic tape 1 is reproduced from the control head 4, passes through a switch 16, and an amplifier circuit 17 obtains a reproduction control signal H, which is then supplied to a delay circuit 14 through a switch 8. The trapezoidal wave G is sampled at the rising edge of the sampling signal with a delay @T2. Through the series of operations described above, the capstan motor 2 is controlled, and the reference signal and the reproduction control signal H become phase-locked and synchronous. Furthermore, in order to maintain the phase lock of the capstan servo during assembly editing, during the playback mode, the pulse train having a higher frequency than the base signal signal produced by the oscillation circuit 6 is divided to create an internal signal with the same frequency as the base signal signal. The frequency divider circuit 7 that generates the reference signal C is divided and output and I
By resetting with , the internal reference signal C and the frequency dividing ratio are kept in a phase-locked synchronized state.

When the mode switching signal E changes to the L level at point b', the switches 8 and 16 are switched to the λ side, and the capstan servo is in the recording mode.The reference signal is amplified by the amplifier circuit 18 and sent from the control head 4 to the magnetic tape 1. recorded in

Furthermore, an internal reference signal C is input to the input signal F of the trapezoidal wave generating circuit 9, and a trapezoidal wave G as shown in FIG. 2 is formed. Furthermore, the comparison signal J is supplied with a frequency division ratio, and a sampling signal K as shown in FIG. 2 is output, and the trapezoidal wave G is sampled at the rising edge. The delay amount T2 is set so that the phase relationship between the delayed signal B and the reproduction control signal H in the phase locked state in the playback mode is the same as the phase relationship between the internal reference signal C and the frequency division ratio crab in the phase locked state in the recording mode. If you have decided on this, there will be no disturbance of the cab stan motor during assembly editing.

In addition, in this embodiment, in order to facilitate comparison with the conventional example, the capstan servo in the regeneration mode was explained using the regeneration control signal as a comparison signal. The delay amount T2 is set so that the error voltage from the S/H circuit and the error voltage in the phase lock state of the recording mode are the same.
It is clear that a similar effect can be obtained by setting .

Effects of the Invention As described above, according to the present invention, even in a format such as 8m/mVTH where no control signal exists,
Excellent effects such as accurate assembly editing can be achieved with a simple circuit configuration.

[Brief explanation of drawings]

Figure 1 is a block diagram of a capstan servo system in an embodiment of the present invention, Figure 2 is a timing diagram explaining the operation of Figure 1, Figure 3 is a block diagram of a conventional capstan servo system, and Figure 4. 3 is a typing diagram explaining the operation of FIG. 3. FIG. 6... Oscillation circuit, 7... Frequency dividing circuit, 9
..... Trapezoidal wave generation circuit, 10 .... S/H circuit, 14 .... delay circuit, 16 .... frequency dividing circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure (C) (R) Figure 4 (F-)

Claims (1)

[Claims] tape feeding means for running the magnetic tape at a predetermined speed;
an electric motor coupled to a tape capstan that drives the magnetic tape; a frequency generator that generates electrical pulses representing the speed of the electric motor in response to rotation of the electric motor; and a reference signal obtained by dividing a pulse train of a predetermined frequency. and a second frequency dividing circuit that generates a comparison signal having the same frequency as the reference signal from the electric pulse obtained from the frequency generator at a predetermined speed of the magnetic tape, During a reproduction operation period, the first frequency division circuit is controlled by the comparison signal to phase-lock the reference signal and the comparison signal, and during a transition period from reproduction operation to recording operation, the first frequency division circuit is controlled. and phase-locks the reference signal and the comparison signal by phase comparison means for generating an error voltage representing a phase difference between the reference signal and the comparison signal and means for controlling the electric motor according to the error voltage. A magnetic recording/reproducing device characterized by: