JPS635322Y2 - - Google Patents

Description

[Detailed explanation of the idea]

This invention relates to a video playback device, particularly a video playback device that distinguishes between an NTSC signal, a PAL signal, and a SECAM signal and outputs a system discrimination signal in a video recorder/player (VTR). For example, in a video recording/playback device that can record and play back signals of two or more formats, such as NTSC and PAL formats, a receiver that can process signals of both formats is required depending on the difference in format. . For example, in order to obtain both NTSC and PAL signals on a cathode ray tube as a normal screen, vertical width correction, color processing circuit switching, video signal band correction, etc. must be performed manually or automatically depending on the differences between the two systems. It is necessary. Also, NTSC system and
Even in a video recording/playback machine that can record and play back signals of two or more systems, such as the PAL system, or both, due to differences in running tape speed, drum rotation speed, or video signal recording/playback system, these can be corrected or switched depending on the system. It is necessary to do this. This invention provides a video reproducing apparatus that can automatically perform corrections caused by the difference in the above-mentioned systems. This invention will be explained in detail below using an embodiment of this invention shown in FIG. In Figure 1, 1
is a system discrimination device that focuses on the difference in the period of the vertical synchronization signal between, for example, the NTSC system and the PAL system,
The reference frequencies within the synchronization signal period are counted and discriminated, and as a result of the discrimination, a high level (H level) signal is output to terminal 2 for, for example, the NTSC system, and a low level (L level) signal for other systems. do. Reference numeral 3 denotes a video signal processing device which superimposes the H level or L level signal outputted by the system discriminator 1 on the video signal applied to the video signal input terminal 4 and outputs it to the video signal output terminal 5. Both the system discrimination device 1 and the video signal processing device 3 are included in the video recording/playback device 6. A concrete example of the system discrimination device 1 and the video signal processing device 3 is shown in FIG. In Figure 2,
The same parts as in FIG. 1 are given the same reference numerals. First, the method discriminator 1 will be explained. In FIG. 2, a tape speed detector 7 has an FG coil 7a for detecting pulses accompanying rotation of the capstan shaft for tape speed control. The means for detecting the pulses accompanying the rotation of the capstan shaft is not limited to the embodiment of this method, but it is also possible to use a method in which a disk having an optical slit around the circumference is attached to the capstan shaft and the transmitted light is photoelectrically converted. 9 is a frequency dividing circuit that divides the detection output of the FG coil 7a, 10 is a control signal amplification device that amplifies the control signal recorded on the tape, and 11 is a frequency of the output signal of the frequency dividing circuit 9 and a control signal amplification device. This is a comparator that compares the frequency of the output signal of the width filter 10 and makes a determination. In this configuration, the first tape speed is now
The characteristics when the PAL recording system and the second tape speed are the NTSC recording system, that is, the vertical frequency, control signal frequency, and recording tape speed, are
Shown in the table.

[Table] Focusing on the control signals recorded on the tape, the tape recorded at the first tape speed (PAL system) is changed to the first tape speed of 23.39 mm/
If you play it at a speed of s, you will get a 25Hz control signal as per the method. However, if a tape recorded in PAL format is used at a second tape speed (NTSC format)
When playing at 33.35mm/s, the frequency of the control signal is 25 (Hz) x 33.35 (mm/s) / 23.39 (mm/s) ≒ 35
.6Hz. Then the second tape speed (NTSC system) 33.35
When a tape recorded at mm/s is played back at the second tape speed, a control signal of 29.97 Hz is obtained as per the method. However, when playing back a tape recorded in the NTSC format at the first tape speed (PAL format), the frequency of the control signal is 29.97 (Hz) x 23.39 (mm/s) / 33.35 (mm/s).
≒21.0 (Hz). On the other hand, the FG coil 7a detects pulses from a gear attached to the capstan shaft.
The FG coil output generates a frequency proportional to the capstan tape feed speed. If the frequency detected by the FG coil 7a at the first tape speed is 401.4Hz, the frequency detected by the FG coil 7a at the second tape speed is 572.4Hz. Therefore, when the frequency is divided by 1√18, the frequencies obtained from the frequency dividing circuit 9 are 22.3 (Hz) and 31.8 (Hz) depending on the first and second tape speeds, respectively. This relationship is shown in Table 2.

[Table] As is clear from Table 2, if the output frequency of the frequency divider circuit is set as above, the control signal frequency during playback of a tape recorded in the PAL system will be at the first or second tape speed. When reproduced, the frequency always becomes higher than the output frequency of the frequency dividing circuit 9. Conversely, the control signal frequency during playback of a tape recorded at the second tape speed (NTSC system) is always lower than the output frequency of the frequency divider circuit 9 when played back at the first or second tape speed. Become. Therefore, the comparator 11 determines by which system the reproduced tape is recorded depending on whether the frequency of the reproduced control signal is higher or lower than the frequency of the frequency dividing circuit. or L
A level signal is output to terminal 2. Next, the video signal processing device 3 will be explained. In FIG. 2, 12 to 16 are resistors, 17 is a transistor, and 18 is a capacitor. The H level or L level output of the system discriminator 1 is applied from terminal 2 to dividing resistors 15 and 16, and the video signal is applied from terminal 4 to the base of transistor 17 via dividing resistors 12 and 13. As a result, an output in which the output of the system discriminator 1 and the video signal are superimposed is obtained at the terminal 5 as the output of the video recording/reproducing device 6, and is applied to the input terminal 20 of the television receiver 19, for example. The receiver 19 detects the H level or L level signal sent superimposed on the video signal from the video recording/playback device 6, and performs NTSC operation if it is H level, and if it is L level. If so, use a system other than NTSC (PAL,
SECAM system and other systems), and performs vertical width correction, color processing circuit switching, video signal band correction, etc. As a result of the discrimination in the system discriminator 1, instead of outputting the H level or the L level, a different code signal or a different frequency signal may be output. Furthermore, the discrimination signal of the system discriminator 1 may be superimposed on an audio signal instead of being superimposed on a video signal, and a signal generated depending on the playback state of the video recording/playback device 6 may be superimposed on the video signal. It may be superimposed on a signal other than the signal to be transmitted to the receiver 19, or it may be transmitted to the receiver 19 independently from the various signals transmitted to the receiver 19. As described above, according to this invention, in a video recording/playback device, NTSC system signals, PAL system signals,
It is possible to discriminate at least two or more scheme signals among the SECAM signal and other scheme signals, and output a scheme discrimination signal according to the result of the discrimination. Furthermore, in a passive device such as a television receiver, the method can be automatically selected by detecting the method discrimination signal, thereby eliminating the need for special manual operations on the receiver.

[Brief explanation of the drawing]

FIG. 1 is a block diagram for explaining one embodiment of this invention, and FIG. 2 is a block diagram for explaining a part of FIG. 1 in detail. In the figure, 1 is a system discrimination device, 3 is a video signal processing device, 4 is a video signal input terminal, 5 is a video signal output terminal, and 6 is a video recording and reproducing device (VTR). Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A tape speed detector that emits an output corresponding to the rotational speed of the capstan shaft, a control signal amplifier that detects and amplifies the control signal recorded on the recording tape, and the tape speed detection described above. A video playback device comprising a comparator that compares each frequency of the detection output of the control signal amplifier and the output of the control signal amplifier, and generates a system discrimination signal corresponding to the recording system of the recording tape based on the comparison result. (2) The video playback device according to claim 1, wherein the system discrimination signal is a different level signal. (3) The video playback device according to claim 1, which is characterized in that a different code signal or frequency signal is used as the system discrimination signal. (4) The video playback device according to any one of claims 1 to 3 of the utility model registration claim, characterized in that the system discrimination signal is superimposed on the video signal and output. (5) The video playback device according to any one of claims 1 to 3 of the utility model registration claim, characterized in that the system discrimination signal is superimposed on the audio signal and output.