1. Field of the Invention
The present invention relates to a color signal reproducing circuit of a magnetic recording and reproducing apparatus, and more particularly to a color signal reproducing circuit to accurately correct phase of reproduced color signal.
2. Description of the Prior Art
In general, a magnetic recording and reproducing apparatus such as a video tape recorder is provided in which a color signal is converted at low range frequency and recorded on magnetic tape or disk, and the color signal is read out on magnetic tape or disk and converted into a chrominance signal before mixing with the luminance signal read by reproducing head.
A conventional color signal reproducing circuit is shown in FIG. 1. Referring to FIG. 1, a video signal from input terminal 1 is read out by the reproducing head in a magnetic recording and reproducing apparatus. The video signal is applied to low pass filter 10 and thus converted into a composite chrominance signal containing 629 kHz.+-.500 kHz.+-.F', whereas F' is phase information of the reproducing head. The composite chrominance signal is applied to an automatic gain controller 20, thus followed up in accordance with the level of the color burst signal and thus controlled in its gain to be converted into a predetermined composite color signal. The gain-controlled composite color signal is applied to a main converter 30 which adopts a difference between the composite color signal and 4.2 MHz.+-.F' frequency signal outputted from a sub-converter 60, and thus produces a 3.5 MHz.+-.500 kHz chrominance signal.
The sub-converter 60 produces a 3.48 MHz.+-.629 kHz.+-.F' frequency signal which includes a 629 kHz.+-.F' frequency signal added phase information signal of the reproducing head to 40 fh reference frequency, whereas fh is horizontal synchronising signal of the video signal, and 3.58 MHz generated by an automatic phase controller 80. The 3.58 MHz.+-.629 kHz.+-.F' frequency signal is outputted through a band pass filter 40 to the main converter 30, then 4.2 MHz.+-.F' of frequency signal is output from the band pass filter 40 and applied to the main converter 30.
Such a color signal reproducing circuit is provided in which color burst signal is detected from output signal of the main converter 30 by burst gate means 70 and applied to the automatic phase controller 80 so as to limit jitter contained within the color burst signal. Further, the automatic phase controller 80 produces gain-controlled 3.5 MHz frequency signal to be applied to the sub-converter 60.
Since the prior art a color signal reproducing circuit, however detects color burst signal after converting video signal into chrominance signal as being color signal, there are problems that the construction is complicate and accurate phase correction of the color burst signal is difficult.