JPS6366118B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a magnetic recording/playback device having special playback functions such as cue, review, still, and fine throw, and also has a color signal recording/playback function.

Conventional configuration and its problems In ordinary magnetic recording and playback devices, the discrimination sensitivity of the so-called color killer circuit that discriminates the presence or absence of color signals always remains constant, even during special playback such as cue, review, and still. Not changed.

Here, a conventional general color killer circuit will be explained using FIG. 1. The horizontal synchronizing signal B is delayed through a delay circuit 5, and a burst signal is extracted from the chroma signal A in a burst gate circuit 1. The burst signal passes through the amplifier circuit 2 and is supplied to the phase detection circuit 3. The output of the oscillator 4 using a crystal oscillator or the like is also supplied to the phase detection circuit 3, and the detected output is input to the killer switch circuit 6 and output as the killer output C.

Further, a conventional SECAM type color killer circuit will be explained using FIG. 2. Horizontal synchronization signal B
passes through the delay circuit 5 and enters the burst gate circuit 1. The color signal A enters the burst gate circuit 1,
Only the burst signal is extracted, passes through the amplifier circuit 2, and then passes through the filter 7. The burst signal that has passed through the tuned amplifier circuit 8 having a frequency of 1/2 of the horizontal synchronizing signal frequency passes through the slicer 9 and enters the detector 10. The output of the detector 10 enters a killer switch circuit 6, from which a killer output C is output.

However, during special playback, noise is generated due to track deviation, and noise is also generated in the reproduced video signal. As mentioned above, the color killer circuit uses a burst gate signal that delays the horizontal synchronization signal of the video signal by a certain phase to extract the burst of the chroma signal, and uses this burst signal to determine the presence or absence of a color signal. During special playback, the burst gate signal and chroma burst signal may become abnormal due to track deviation noise.
Color killer sensitivity changes more than normal playback. In addition, the relative speed changes during queue and review playback, but if this is not corrected by changing the rotational speed of the rotating video head, the burst signal that passes through the delay line will not be able to be extracted, resulting in color killer sensitivity. changes. Moreover, especially in the case of the SECAM method, since discrimination from the PAL method is performed based on the frequency difference every 1H, the color killer determination will change even more if the relative speed changes. Therefore, in the conventional apparatus, there was a problem in that the color killer did not operate normally during special reproduction, making it impossible to obtain a stable reproduction signal.

Purpose of the Invention The purpose of the present invention is to solve the above-mentioned conventional drawbacks, and an object of the present invention is to provide a magnetic recording/playback device that can operate the color killer normally even when performing special playback of queues, reviews, stills, etc. do.

Structure of the Invention In order to achieve the above object, the magnetic recording and reproducing apparatus of the present invention is a two-head helical scan type magnetized recording and reproducing apparatus, and includes cue, review, still, etc.
The configuration includes a sensitivity switching means for switching the sensitivity of a discrimination circuit that discriminates the presence or absence of a color signal when performing special reproduction such as slow motion.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on the drawings.

FIG. 3 is a circuit block diagram of a color killer circuit, in which the same components as those shown in FIG. 1 are given the same reference numerals and their explanations will be omitted. In FIG. 3, 11 to 13 are sensitivity switching switch circuits for switching the killer sensitivity during special playback,
The switch circuit 11 changes the width of the burst gate, the switch circuit 12 changes the level of the burst signal, and the switch circuit 13 changes the set point of the killer switch. Any one of these sensitivity changeover switch circuits 11 to 13 may be used, or any combination of a plurality of them may be used.

FIG. 4 is a circuit block diagram of a color killer circuit in the case of the SECAM system, and the same components as those shown in FIG. 2 are given the same reference numerals and their explanations will be omitted. In this embodiment as well, sensitivity changeover switch circuits 11 to 13 are used, and their operation is similar to that of the circuit shown in FIG.

In this way, during special playback, the sensitivity of the color killer is switched by the sensitivity changeover switch circuits 11 to 13, so that no matter what mode is played back, a stable playback signal can be obtained without color fading.

Effects of the Invention As explained above, according to the present invention, the sensitivity of the color killer is switched during special playback, so that no matter what mode the playback mode is used, a stable playback signal can be obtained without color fading. I can do it.

[Brief explanation of drawings]

Fig. 1 is a circuit block diagram of a conventional general color killer circuit, Fig. 2 is a circuit block diagram of a conventional SECAM type color killer circuit, and Fig. 3 is a circuit block diagram of a magnetic recording/reproducing device according to an embodiment of the present invention. Circuit Block Diagram of Color Killer Circuit FIG. 4 is a circuit block diagram of a color killer circuit of a SECAM type magnetic recording/reproducing apparatus in another embodiment of the present invention. 11, 12, 13... Sensitivity changeover switch circuit.

Claims (1)

[Claims] 1. A two-head helical scan type magnetic recording and playback device, which is equipped with a sensitivity switching means for switching the sensitivity of a discrimination circuit that discriminates the presence or absence of a color signal when performing special playback such as cue, review, still, and slow. Magnetic recording and playback device.