JPS63224559A - Video signal recording and reproducing device - Google Patents

Abstract

PURPOSE:To make noise at the time of switching not remarkable on a reproducing screen by applying the switching of a television/video switching circuit during the vertical blanking period of a video signal. CONSTITUTION:When a video recording key of a key input means 14 is operated, a control signal is supplied to switches 9, 12 by a system controller 15 and the recording of a program is started. When a program different from the recorded program is desired for watching at a television receiver 16 after the start of recording, a television/video changeover switch 17 is depressed. The system controller 15 detects the vertical blanking period of a video signal by using the vertical synchronizing signal fed from a vertical synchronizing signal separation means 13 independently of the timing when the switch 17 is depressed. Then a signal switching the changeover circuit 5 is generated during the vertical blanking period and the circuit 5 is switched from the position V to the position T.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a video signal recording and reproducing device.

[Summary of the invention]

In this invention, the switching operation of the television/video switching circuit is performed within the vertical blanking period of the video signal, so that the noise generated due to the switching operation of the television/video switching circuit is eliminated during recording. , to provide a video signal recording/playback device that is not conspicuous on the playback screen.

[Conventional technology]

In a video signal recording and reproducing device such as a video tape recorder (hereinafter referred to as a VTR), the RF multiplied signal from the antenna is either supplied directly to the antenna terminal of the TV, or the RF multiplied signal from the antenna is selected by the VTR's chainer. A television/video switching circuit section is provided which modulates the demodulated signal again, converts it into an RF multiplied signal of an empty channel of the television, and switches whether or not to supply this RF multiplied signal to the antenna terminal of the television. There is.

FIG. 3 is a diagram showing the above-mentioned television/video switching circuit section.

In the same figure, the RF multiplied signal received by the antenna (1) is supplied to and distributed to the distributor [2].
RF multiplied signal from one output terminal (2a) of VTR
A tuner (3) selects a channel, and the selected signal is supplied to a detector (7) via an intermediate frequency amplification circuit (6) and detected. The video signal from this detector (7) is then supplied to a recording system (not shown). Also distribution p5
The RF signal from the other output terminal (2b) of f2) is supplied to the input terminal of the switching circuit (5) on the television side (indicated by T in the figure). The signal from the detector (7) is sent to the input terminal on the V 'I' R side (indicated by ■ in the figure) of this switching circuit (5), and the signal from the detector (7) is sent to the RF of the open channel by the RF modulator (4).
A double signal modulated signal is supplied, and the output of the switching circuit (5) is supplied from the RF output terminal (5t) of this VTR to the antenna terminal of the television. Furthermore, when the VTR is equipped with a video output terminal, the signal from the detector (7) is sent to the video output terminal (7t) of the VTR without passing through the RF modulator (4). Supplied to the input terminal.

In the above TV/video switching circuit section, the switching circuit (
5) is a switching signal that is generated in response to the operation of a changeover button switch (not shown) that can be operated by the user at any time. Can be switched. Conventionally, this switching operation is not performed with particular consideration given to the timing with respect to the video signal.

[Problem that the invention seeks to solve]

By the way, every time a switching operation is performed in the switching circuit (5), the antenna terminal of the TV with a certain value of impedance is connected to the output terminal (2b) of the distributor (2) via the switching circuit (5). Because the output terminal (2b) of the distributor (2) is connected or disconnected, there is a large variation in impedance. When the impedance on the output terminal (2b) side fluctuates, both output terminals (2a
) (2b) is finite, the RF multiplied signal level supplied from the output terminal (2a) of the distributor (2) to the tuner (3) also fluctuates.

In order to suppress this level fluctuation, the tuner (3)
The gain is adjusted by the AGC circuit (i), but it takes some time until the gain is adjusted to an appropriate value, and in the transient state until the gain is adjusted, the tuner (
3) The level of the signal output from 3) fluctuates. This signal level fluctuation becomes noise, and during recording operation,
When this switching circuit (5) performs a switching operation, this noise is recorded in the video signal. Then, if that noise is present in the video section, on the playback screen of the video signal,
This noise appears and the image quality deteriorates.

If the circuit (5) is switched while the program selected by the VTR tuner (3) is being monitored on the dedicated monitor TV,
Noise generated by the switching operation of this circuit (5) may appear on the screen of the monitor-only television, degrading the image quality.

In order to prevent the above-mentioned noise generation, as shown in Fig. 4, the output end (2b) of the distributor (2) and the switching circuit (
An isolation amplifier (2) is connected between the T-side terminal of
2) may be inserted. However, this isolation amplifier (22) is expensive, and its output signal is distorted in response to excessive input. Therefore, it is not appropriate to use an isolation amplifier.

[Means for solving problems]

In this invention, the video signal obtained by demodulating the first RF multiplied signal from the antenna (1) is supplied to the recording system, and the demodulated video signal from the first RF multiplied signal RF modulator (4) is supplied to the recording system. In a video signal recording and reproducing apparatus which supplies a modulated second RF double signal to a monitor via a television/video switching circuit (5), the switching operation of the television/video switching circuit (5) is performed by an antenna (1). ) is configured to be performed within the vertical blanking period of the video signal by the first RF multiplied signal.

(Function) Since the switching operation of the TV/video switching circuit (5) is performed during the vertical blanking period of the video signal by the RF multiplied signal from the antenna (1), the noise during this switching is not noticeable on the playback screen. It disappears.

〔Example〕

FIG. 1 is a block diagram of one embodiment of the present invention. It should be noted that means equivalent to those shown in FIG. 4 are given the same reference numerals.

In FIG. 1, when an RF multiplied signal is received by an antenna (1), this RF signal is sent to a distributor (2), a tuner (3), and a tuner (3).
), which is supplied to a detector (7) via an intermediate frequency amplifier (6). The signal output from the wave detector (7) is supplied to the magnetic head (10) via a recording signal processing circuit (8) and a recording/reproduction changeover switch (9).

The signal from the detector (7) is also sent to the antenna terminal of the television (16) via the normal/regeneration switch (12), RF modulator (4), switching circuit (5), and output terminal (5t). Supplied. Note that the switch (12) is connected to the normal mode side (indicated by N in the figure), that is, the detector (7) side in modes other than the reproduction mode. Therefore, in playback mode, the head (
The reproduced signal from 1O) is supplied to the reproduced signal processing circuit (11) and restored to the original video signal, which is supplied to the RF modulator (4) via the switch (12). When this reproduction mode is entered, the switching circuit (5) is switched to the V side by a switching signal from the system controller (15), for example, and the reproduced image can be monitored on the television (16).

The RF multiplied signal received by the antenna (1) is also supplied to the antenna terminal of the television (16) via the distributor (2) and the switching circuit (5).

(15) is a system controller (hereinafter referred to as system controller) equipped with a micro combinator, and a switch (
9) and (12) are switched by a switching signal from this system controller (15). (13) is a vertical synchronization signal separating means that is supplied with the signal from the detector (7), separates a vertical synchronization signal from this signal, and supplies this vertical synchronization signal to the system controller (15).

When recording television programs, a switching circuit (5) is usually used.
is connected to the V side, and a signal from the RF modulator (4) is supplied to the antenna terminal of the television (16) to perform a recognition of the program to be recorded. After that, key manual means (1
When the recording key 4) is operated, a control signal is supplied from the system controller (15) to the switches (9) and (12), and recording of the program is started. After starting recording, if the user wants to watch a program on the television (16) that is different from the program being recorded, the user presses the television/video changeover button switch (17).

Then, the system controller (15) uses the vertical synchronization signal supplied from the vertical synchronization signal separation means (13) to control the vertical blanking period of the video signal, regardless of the timing at which the switch (17) is pressed. Detect this.

A switching signal for switching the switching circuit (5) is generated within the vertical blanking period. In this case, the switching circuit (5) is switched from the V side to the T side by this switching signal.

As a result, the noise generated with the switching operation of the TV/video switching circuit occurs within the vertical blanking period of the video fH, so even if it is recorded, the
The above-mentioned noise is not noticeable on the playback screen,
Good images can be obtained.

Furthermore, even if the switching circuit (5) is switched while the monitor-only TV (16M) is monitoring a program received by the VTR tuner (3), the Noise associated with switching does not appear.

In this case, the recorded video may be displayed on a monitor-only TV (16
M), the program currently being broadcast on TV (
16), when the switching circuit (5) is switched to the T side, noise at the time of this switching may appear on the screen of the monitor television (16M). To prevent this, the vertical synchronization signal of the playback signal is separated and the system controller (15
) so that the switching operation of the switching circuit (5) is performed within the vertical blanking period of the reproduced signal.
may be configured.

FIG. 2 is a flow chart of the operation of the system controller (15) for performing the above-mentioned switching operation of the television/video switching circuit within the vertical blanking period of the video signal.

In addition, in the example shown in the figure, the system controller (15)
The switching operation of the switching circuit (5) is controlled, and the switching operation control circuit to which the vertical synchronizing signal from the vertical synchronizing signal separating means (13) and the signal from the switch (17) is supplied is a system controller (15). may be provided separately, and the switching operation of the switching circuit (5) may be controlled by this control circuit rather than by the system controller (15), that is, when the switch (17) is pressed by the operator, When the first vertical synchronization signal is supplied to the above-mentioned control circuit after being pressed, a switching signal is sent from the above-mentioned control circuit to the switching circuit (5) within the vertical blanking period of the video signal.
).

〔Effect of the invention〕

According to the present invention, since the switching operation of the television/video switching circuit is performed during the vertical blanking period of the video signal, the switching operation of the television/video switching circuit can be easily performed. It is possible to realize a video recording and reproducing device in which the noise caused by noise does not stand out on a television screen.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a flowchart of an operation for performing a switching operation of a television/video switching circuit within a vertical blanking period of a video signal.
FIG. 3 is a diagram showing a conventional example, and FIG. 4 is an example of a circuit for preventing the generation of noise caused by switching operations. (1) is the antenna, (4) is the RF modulator, (5)
is a TV/video switching circuit.

Claims (1)

[Claims] A video signal obtained by demodulating the first RF signal from the antenna is supplied to the recording system, and the first RF signal and the RF
In a video signal recording and reproducing device that supplies a second RF signal obtained by modulating the demodulated video signal from a modulator to a monitor via a television/video switching circuit, switching by the television/video switching circuit is provided. A video signal recording and reproducing device that operates during a vertical blanking period of the video signal by the first RF signal from the antenna.