JPS6053997B2 - magnetic recording and reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a video recording and reproducing device, particularly a video recording and reproducing machine (
The present invention relates to a video recording and reproducing apparatus that can discriminate among systems such as an NπC system signal, a PAL system signal, and a SECAM system signal to obtain a regular reproduction signal in a VTR (VTR).

In conventional VTRs, when a cassette is loaded, it is impossible to automatically determine the television system recorded on the tape of the loaded cassette and to obtain a regular reproduction signal.

In view of the above points, the present invention provides a VTR equipped with a discrimination circuit that automatically discriminates between the NTSC system, PAL system, SECAN4 system, etc.

Hereinafter, this invention will be explained in detail using an embodiment of the invention shown in FIG. In FIG. 1, 1 is a reference oscillator, 1a is a tuning fork that is an oscillation source for the first tape speed Vp, 1 is a tuning fork that is an oscillation source for the second tape speed VN, and 2 is a reference oscillator 1. 3 is a frequency dividing circuit that divides the oscillation frequency of the reference oscillator 1;
4 is an amplifier that amplifies the control signal recorded on the tape; 5 is a comparator that compares the frequency of the output of the frequency dividing circuit 3 with the frequency of the output of the control signal amplifier 4 and outputs a discrimination signal; 6 is a comparator 5 is a gate circuit that selects a color signal from the color signal input 7 according to a discrimination signal; 8 is a comparator 5;
NTSC color circuit that operates according to the discrimination signal of 9
10 is a PAL signal phase detector; 10 is a switch circuit that performs switching depending on the presence or absence of the output of the phase detector 9; 11 is a PAL color circuit that operates according to the switch circuit 10;
13 is an FH/2 resonator that resonates with the output of the FM detector 12; 14 is an amplitude detector that amplitude-detects the output of the resonator 13; 15 is the amplitude detector 14; The switch circuit 16 that responds to the output and inhibit signal from the switch circuit 10 is a SECAM color circuit that operates according to the switch circuit 15, and the switch circuit 17 detects that it is a black and white signal according to the output level of the switch circuits 10 and 15. It is an OR circuit.

In this configuration, the first tape speed 9 corresponds to the PAL system (or SECAM system), and the second tape speed VN corresponds to the vC system, and the vertical frequency of both systems is Table 1 shows the relationship between the frequency of the control signal and the tape speed. becomes.

Next, the tape recorded at the second tape speed ■N is
When played at tape speed ■N, it is 29.97Hz according to the method.
control signal.

However, when a tape recorded using the VC system is played back at the first tape speed 9, the control signal becomes .

On the other hand, if the oscillation frequency of the reference oscillator 1 is 1867Hz at the first tape speed Vp and 2663Hz at the second tape speed, then the frequency dividing circuit 3
When the frequency is divided by 1, the frequency obtained from the frequency divider circuit 3 is
23. depending on the first and second tape speeds VP and VN, respectively.
04HZ, 32.87HZ.

This relationship is shown in Table 2. As is clear from Table 2,
If the output frequency of the frequency divider circuit 3 is set as above, the PA
The control signal frequency of the tape recorded in the L method is always reproduced higher than the output frequency of the frequency dividing circuit 3 when reproduced at the first or second tape speed 9 or VN.

Conversely, the control signal frequency of the tape recorded at the second tape speed VN is always reproduced lower than the output frequency of the frequency dividing circuit 3 when reproduced at the first or second tape speed Vp or VN. Ru.

Therefore, depending on whether the frequency of the reproduced control signal is higher or lower than the frequency of the frequency dividing circuit 3, it is possible to determine by which system the reproduced tape is recorded. When this determination result is expressed in a truth table as shown in Table 3, whether the tape speed is the first or the second, the tape being played back is at the first tape speed V.
This means that if the tape was recorded at the second tape speed VN, the output of the comparator 5 will be at the L level, and if it is recorded at the second tape speed VN, the output from the comparator 5 will be at the H level. .

If it is determined that the tape was recorded using the formula,
The N'TSC color circuit 8 is activated via the gate circuit 6.

As a means of activation, for example, when the level is not high, the NTS
The power supply circuit of the C color circuit 8 may be turned off and turned on when it is at H level. Next, when the output of the comparator 5 is at the L level, it is assumed that the recorded television system is the PAL system or the SECAM system, and the color signal from the color signal input 7 is output from the phase detector 9 of PAL and the FM of SECAM. The signal is supplied to the detector 12 via the gate circuit 6. To determine whether the video signal is PAL or SECAM, the phase detector 9 or the FM detector 12 discriminates between the PAL burst signal and the SECAM ident signal included in the video signal. In the case of a PAL signal, a detection output signal is obtained from the phase detector 9, and the PAL side output terminal 10a of the switch circuit 10 is set to H level, the SECAM side output terminal 10b is set to L level, and the PAL circuit 11 is operated.

When it is a SECAM signal, a detection output signal is obtained from the FM detector 12, and an H level signal is obtained from the switch circuit via the resonator 13 and the amplitude detector 14. Then, the SECAM color circuit 16 is operated. Next, the output signals of the switch circuits 10 and 15 are supplied to the OR circuit 17, and the SEC
Only when the signal is not an AM signal, the output of the OR circuit 17 is set to L level, and it is determined that the video signal is black and white broadcasting.

Note that if the inputs of the OR circuit 17 are both at H level at this time, this also indicates that either the PAL discrimination system or the SECAM discrimination system is malfunctioning, so such malfunction can be detected and , the discrimination sensitivity to the input color signal is PAl. Since the phase detector of the discrimination system is several steps superior to the combined type of FM detector and amplitude detector of the SECAM discrimination system, the input signal is PAl. This makes it possible to determine whether the method is a reliable method or not. As explained above, the present invention is a magnetic recording and reproducing device that determines and reproduces the regular television system from the control signal and input signal recorded on the tape, so even if the system is unknown or the set is It is possible to obtain a magnetic recording and reproducing device that can automatically determine the method and obtain a correct image, and can be applied to a wide range of applications.

[Brief explanation of the drawing]

The figure is a block diagram showing an embodiment of the magnetic recording/reproducing apparatus of the present invention. In the figure, 1 is the reference oscillator, 5 is the comparator, and 8 is the NTSC
9 is a phase detector, 11 is a PAL color circuit, 12 is an FM detector, and 16 is a SECAM color circuit.

Claims (1)

[Claims] 1 The first reference oscillation frequency is lower than the frequency of the control signal recorded at the first tape speed obtained when playing back at the first tape speed, and the second reference oscillation frequency is lower than the frequency of the control signal recorded at the first tape speed obtained when playing back at the first tape speed. The second reference oscillation frequency is set higher than the frequency of the control signal recorded at the tape speed, and the second reference oscillation frequency is lower than the frequency of the control signal recorded at the first tape speed obtained when playing back at the second tape speed. a reference oscillator set higher than the frequency of the control signal recorded at the second tape speed obtained when playing back at the second tape speed; The frequency of the recorded control signal is compared with the frequency of the second control signal.
a comparator that compares the second reference oscillation frequency with the frequency of the control signal recorded on the tape to determine whether the tape was recorded using the NTSC system or another system when reproducing the tape at a tape speed of A PAL system determining means for phase-detecting the video signal recorded on the tape and extracting a subcarrier to determine whether or not it is recorded in the PAL system; performing FM detection on the video signal recorded on the tape; S to determine whether or not it was recorded using the SECAM method
A magnetic recording and reproducing device equipped with an ECAM system discrimination means.