JPS5827594Y2 - magnetic recording and playback device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a magnetic recording and reproducing device (hereinafter referred to as VTR) for recording and reproducing television signals. When the characteristics of the signal processing system are switched depending on whether the signal is a current signal or not, switching noise at the time of the switching force is not displayed on the screen.

Conventionally, whether the television signal to be processed is a color or monochrome signal is detected by the presence or absence of a burst signal, and the characteristics of the signal processing system are switched to be suitable for color or monochrome signals based on the detection signal of this detection means. ing.

However, due to the response characteristics of the detection means, there is a problem in that the detection signal is shifted to the middle part of the screen, and noise accompanying this switching appears in the projected image.

The present invention eliminates this problem and is configured so that the switching is always performed in the vicinity of the vertical synchronization signal that does not appear in the projected image.

One embodiment will be described below with reference to the drawings.

In the drawings, reference numeral 1 denotes an input terminal to which a television signal to be recorded is input, and the luminance is controlled by an input filter 3Vc whose characteristics are switched by the output from a detection signal generating means 2 for discriminating between a color signal and a monochrome signal, which will be described later. The signal components are taken out and recorded by the recording signal processing circuit 4.
After processing such as C, emphasis, white clip, etc., the signal is frequency modulated.

The characteristics of this frequency-modulated signal are switched by the output of the detection signal generating means 2.The characteristics of this frequency-modulated signal are switched by the output of the detection signal generating means 2. The head device 8VC is guided to record on the magnetic tape.

'Jfc, part of the output of the bypass filter 5,
During recording, I/c is guided to a frequency demodulator 11TIC via a bypass filter 10 whose characteristics are switched by the changeover switch 9 connected to the R terminal and the output of the detection signal generating means 2, and is demodulated.

The demodulated signal is led to an output signal processing circuit 13Vc via a bypass filter 12 whose characteristics are switched by the output of the detection signal generating means 2, and is subjected to processing such as de-emphasis and clamping, and then monitored via an output terminal 14. The image is sent to a receiver (not shown) as a monitor image.

During playback vCrt, said selector switch 7, 9II'iP
The reproduction signal from the rotating magnetic head device 8 is guided to the above-mentioned I-pass filter 10 via the changeover switch 7, the reproduction amplifier 15 button, and the changeover switch 9, and the subsequent operation is the same as during recording. is guided to the monitor receiver.

The above is the same as the conventional magnetic recording and reproducing apparatus of this type.

Next, the configuration of the detection signal generating means 2, which is a feature of the present invention, will be explained.

16ri is a head switching switching pulse generation circuit, and the head switching pulse (signal phase synchronized with the vertical synchronization signal of the television signal to be recorded or the reproduced television signal) from this pulse generation circuit 16 (Fig. 2) b) The rt delay circuit 17 generates a pulse signal (FIG. 2C) that is synchronized with the rising or falling edge of the pulse signal and is located in the vertical blacking period of the television signal to be recorded or the reproduced television signal (FIG. 2e). The signal is delay-shaped and guided to the first AND gate circuit 18 and the second AND gate circuit 19.

Reference numeral 20 denotes a signal terminal to which a television signal to be recorded or a reproduced television signal is applied, and is connected to a discrimination circuit 21 which discriminates between a color television signal and a monochrome television signal based on the presence or absence of a conventionally known burst signal. .

The detection signal (FIG. 2a) whose level changes in the color and black and white signals of this discrimination circuit 21 is led to the first AND gate circuit 18 and is also sent to the second AND gate circuit 19 via the inverter 22. It has been entered.

The output of the first AND gate circuit 18 is applied to the set terminal of the flip-flop 23, and the output of the second AND gate circuit 19 is applied to the reset terminal of the flip-flop 23.

That is, the flip-flop 23ri, the discrimination circuit 2
Since it is set and reset by the first pulse of the signal C after the first discrimination output a changes, its output becomes as shown in FIG. 2d.

Therefore, with this output d, each of the above filters 3°5.10
．． If the characteristics of No. 12 are switched, the timing of this switching is carried out during the vertical blanking period of the television signal e, so that the noise generated at the time of switching will not appear on the reproduced image.

As described above, according to the present invention, the switching of the characteristics that is pressed in the signal processing system is performed during or near the vertical blanking period of the television signal, so that noise components at the time of switching appear in the projected image. It is something that never happens.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a waveform diagram illustrating the same operation. 1.20... Input terminal, 3.5.10.12... Filter with switchable characteristics 4... Recording signal processing circuit,
6.15...Amplifier, 11...Frequency demodulator, 13
... Output signal processing circuit, 16... Head switching switching pulse generation circuit, 17... Delay circuit, 18.1
9... AND gate circuit, 21... Discrimination circuit, 21
...Invar 7.23...Flip-flop.

Claims (1)

[Scope of utility model registration request] means for creating a pulse that is phase synchronized with a vertical synchronization signal of a television signal to be recorded or reproduced and located in the vicinity of a vertical blanking interval of the television signal; discriminating means for discriminating whether a television signal is a color television signal; A magnetic recording and reproducing apparatus comprising a processing circuit for the television signal, in which a period filter characteristic at a time point 1 of occurrence is switched.