JPH0376044A - Video recording and reproducing device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a device for reproducing video signals recorded on a magnetic tape using a rotary head, in which cylinder speed control during reproduction is performed using a synchronization signal of the reproduced video signal. This invention relates to a video recording and reproducing device that can perform the following functions.

BACKGROUND OF THE INVENTION In recent years, video recording and reproducing devices (hereinafter abbreviated as VTR) have become widespread, and opportunities to play back soft tapes have increased, creating a demand for reducing jitter caused by compatible tapes.

Figure 2 is a block diagram of cylinder speed control during video signal reproduction of a conventional VTR, and 21 is cylinder FG2.
2 is an F/V conversion circuit that converts the FG frequency into voltage, 23
24 is a speed comparison circuit, 24 is a ripple filter, 26 is a V/I conversion circuit that converts an error voltage into a current, and 26 is a cylinder motor.

The conventional cylinder speed control circuit configured as described above during video signal reproduction of a VTR controls the number of revolutions of the cylinder to 21
The F/V conversion circuit 22 converts the frequency into a frequency, and the F/V conversion circuit 22 converts the frequency into a voltage for comparison with a speed reference.
The error with respect to the speed reference is detected, and the ripple filter 24 removes this error signal ripple. Since the cylinder motor 26 is generally current-driven, the V/I conversion circuit 26
converts the voltage into current and feeds it back to the cylinder motor 26.

Problems to be Solved by the Invention However, in the above configuration, there is a limit to the accuracy of the FG, and the accuracy directly affects the time axis fluctuation of the video signal.

In view of the above-mentioned problems, the technical object of the present invention is to prevent time axis fluctuations from occurring regardless of the accuracy of the FG.

Means for Solving the Problems The video recording and reproducing apparatus of the present invention includes: a reproducing head for reproducing signals recorded on a magnetic tape; a cylinder equipped with the reproducing head; a motor for rotating the cylinder;
a sampling circuit that samples a synchronization signal from the video signal reproduced by the playback head; a first F/V conversion circuit that converts the frequency of the synchronization signal sampled by the sampling circuit into a voltage; an FG circuit that generates a frequency signal, and the FG circuit that generates a frequency signal;
A 20th F/V conversion circuit converts a signal obtained by the circuit into a voltage opposite to its frequency, and a synchronization signal obtained by the sampling circuit is included. Second F
A switch for switching the output of the /V conversion circuit, a speed comparison circuit for comparing the voltage output of the switch with a voltage to be used as a speed reference, and a voltage for converting the error signal detected by the comparison circuit into a current. The present invention is characterized by comprising a current conversion circuit.

According to the above-described configuration, the present invention samples a synchronization signal of a reproduced video signal using a sampling circuit, converts the frequency of the sampled synchronization signal into a voltage, and compares the converted voltage with a reference voltage to detect a speed error. The rotational speed of the motor that drives the cylinder is then controlled based on the error signal.

Embodiments Hereinafter, VTRs according to embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a block diagram of cylinder speed control during video signal reproduction according to an embodiment of the present invention. In Figure 1, 1 is a playback head that outputs a video signal from the magnetic tape, 2 is a playback amplifier that amplifies the output of the playback head 1 to an appropriate level, and 3 is FM demodulation of the video signal amplified by the playback amplifier 2. 4 is a sampling circuit that samples a horizontal synchronizing signal (hereinafter referred to as Hs y, nq) from the FM demodulated signal; 5 is a sampled II
The first F converts the frequency of s 7E1.0 into voltage.
/V conversion circuit, 6 is an input/unmanned power discrimination circuit that determines the presence or absence of Hsync in the reproduction signal, 7 is FGl that detects the rotation speed of the cylinder, s is a second F/V that converts the frequency of the FG output into voltage Conversion circuit, 9 is input/unmanned power discrimination circuit 6
a switch that switches the F/V conversion circuits 5 and 8 by;
1o is a speed comparison circuit that compares the speed signal obtained from switch 9 with a reference signal and detects a speed error; 11 is an error signal ripple filter; 12 is a voltage-current conversion circuit;
3 is a motor that drives the cylinder.

The operation of the VTR configured as described above will be explained.

A video signal recorded on a magnetic tape is reproduced by a reproduction head 1, the reproduced signal is amplified to an appropriate level by a reproduction amplifier 2, and demodulated by an FM demodulation circuit 3. The video signal demodulated by the FM demodulation circuit 3 is converted to Hsy by the sampling circuit 4.
na is sampled and sampled Hsyn
The frequency of a is converted into a voltage by the F/V conversion circuit 6. Also, at the same time, it is attached to the cylinder and 9FG7
The number of rotations of the cylinder is converted to frequency, and F/V
The conversion circuit 8 converts the voltage signal into a voltage signal corresponding to the rotation speed. The switch 9 connects the sampling circuit 4 to
Under control from the input/unmanned power discriminating circuit 6 which determines whether or not c is being input, the output is switched to the F/V conversion circuit 5 when the signal is input, and to the F/V converting circuit 8 when the signal is unmanned. The error of the signal switched by the switch 9 with respect to the speed standard is detected by the speed comparison circuit 10, the ripple is removed by the ripple filter 11, and then converted into a current by the voltage-current conversion circuit 12, which rotates the cylinder. Feedback is applied to the cylinder motor 13.

As mentioned above, the H of the video signal reproduced during video signal reproduction is
By controlling the speed of the cylinder that feeds back the error signal between the syna frequency and the reference frequency, time-axis fluctuations in the video signal are reduced.

Effects of the Invention As described above, according to the present invention, since the speed of the cylinder is controlled by the synchronization signal of the reproduced video signal, it is possible to reduce the time axis fluctuation of the reproduced video signal, and it is possible to produce beautiful reproduced images without horizontal shaking. The effect is that it can be provided.

[Brief explanation of drawings]

FIG. 1 is a block diagram of cylinder speed control during reproduction in a magnetic recording and reproducing apparatus according to an embodiment of the present invention, and FIG.
FIG. 3 is a block diagram of cylinder speed control during regeneration of TR. 1... Playback head, 2... Playback amplifier, 3... FM demodulation circuit, 4... Sampling circuit, 6... Frequency - Voltage conversion circuit 0>
, 6... A circuit for determining the presence or absence of a reproduced video signal, 7...
...FG circuit, 8... Frequency-voltage conversion circuit (2), 9... Changeover switch, 10...
...Speed comparison circuit, 11...Ripple filter, 12...Voltage-current conversion circuit, 13...
・Cylinder motor

Claims (1)

[Claims] A playback head for playing back signals recorded on a magnetic tape, a cylinder equipped with the playback head, a motor for rotating the cylinder, and a sampling circuit for sampling a synchronization signal from the video signal played back by the playback head. A first F/V conversion circuit converts the frequency of the synchronization signal sampled by the sampling circuit into a voltage, an FG circuit generates a signal with a frequency corresponding to the rotation of the cylinder, and a signal obtained from the FG circuit is converted into a voltage. a second F/V conversion circuit that converts into a voltage opposite to the frequency; a switch that switches outputs of the first and second F/V conversion circuits depending on the presence or absence of a synchronization signal obtained from the sampling circuit; A video recorder comprising: a speed comparison circuit that compares the voltage output of a switch with a voltage that should serve as a speed reference; and a voltage-current conversion circuit that converts an error signal detected by the comparison circuit into a current. playback device.