JPS6130393Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a video signal recording/playback device.
More specifically, the present invention relates to a device for reducing unnecessary signals such as ghosts present in television signals in such devices.

This invention proposes a method for recording a television signal containing ghosts on a video tape recorder (VTR) and playing it back by inputting it to the television receiver from the RF terminal rather than taking it out from the VTR's video out terminal. Based on a self-viewing experiment, it was found that ghosts were more visible. The present invention aims to improve this.

Generally, television receivers use an aperture correction circuit to visually improve the frequency characteristics, and this circuit makes the outline of the image clear by creating orthogonal components of the high-frequency components of the signal. When a television signal is recorded and played back on a VTR, the phase characteristics during recording and playback are matched, so the playback signal is essentially equivalent to the input television signal, and the television signal is received at the video out terminal. When applying it to a receiver, there is not much difference from directly monitoring the input television reception signal. However, when converting the VTR playback output to single-band RF and detecting and processing it again in the television receiver, the VSB in the band filter of the RF modulator and the intermediate frequency stage of the television receiver
The orthogonal components of the high-frequency components are increased by a filter, etc., and are further emphasized by an aperture correction circuit, etc., resulting in a glaring image, and in particular, ghost components are emphasized.

The figure is a circuit diagram of an embodiment of the present invention that solves the above-mentioned problems. The video signal reproduced from tape 10 and containing unnecessary components such as ghosts is separated into a luminance signal path 18 and a chrominance signal path 20 by filters 14 and 16, respectively. Luminance signal path 18 is FM
The color signal path 20 includes a demodulation circuit 22, a de-emphasis circuit 24, and a noise canceller circuit 26.
The luminance and chrominance signals of each signal path, which includes a frequency converter 28, a comb filter 30, and a delay circuit 32, are summed by an adder 24 to form the original video signal.
Such a configuration is well known as a chroma low frequency conversion reproduction method. The signal from adder 34 is applied to RF out terminal 40 via video out terminal 36 or RF modulator 38. This terminal 40 has RF
A monitor receiver 42 is connected in an input/output connected state.

According to the present invention, the noise canceling level of the noise canceling circuit 26 is changed in order to reduce the effect that unnecessary signals such as ghosts are emphasized and appear conspicuous on the image receiver 42 as described above.

As is well known, the noise canceller circuit 26 passes a video signal (demodulated luminance signal) containing noise through a high-pass filter, clips the obtained high-frequency signal component, and inverts the phase of the noise component. Noise is removed from the video signal by mixing it into the original video signal. Therefore,
The noise canceller circuit 26 sets the level at which high frequency signal components are clipped. For example, a potentiometer 44 as shown is provided. In the present invention, this clip level is controlled by detecting the connection of the RF out terminal. That is, the high-frequency level of the signal above a predetermined level is lowered in advance to cope with the enhancement effect within the image receptor 42. Therefore, unnecessary signals such as ghosts are eliminated.
There is no noticeable effect on the RF-connected monitor receiver 42. The control circuit 46 is for detecting the RF interface and controlling the noise canceling level of the noise canceling circuit 26, and its detailed design is easy for those skilled in the art.

[Brief explanation of drawings]

The figure is a circuit diagram of an embodiment of the present invention. In the figure, 26 is a noise canceller circuit, 44 is a clamp level setting means, and 46 is a control circuit.

Claims (1)

[Scope of utility model registration request] When recording and playing back video signals that include unnecessary signals such as ghosts, the noise canceling level of the playback side noise canceller circuit is increased depending on the connection of the television receiver to the RF out terminal. A device for reducing unnecessary signals such as ghosts in a video recording/playback device, characterized by attenuating the range level.