Magnetic recording/reproducing apparatus

Claim 2

1 . A magnetic recording/reproducing apparatus for recording a video signal onto a recording medium and reproducing the recorded video signal from the recording medium, comprising: a recording and a reproducing magnetic head (10,11); means (22) for processing a recording luminance signal ; means (24) for processing a reproduced luminance signal; means (23,26) for processing a recording chrominance signal; and means (25,27) for processing a reproduced chrominance signal; said recording chrominance signal processing means (23,26) including: continuous oscillation signal generating means (32,33) for generating a continuous oscillation signal having the same gain and phase as those of the color burst signal of the chrominance signal; switch means (35) normally passing the chrominance signal and, during a period including the color burst signal and longer than the duration of the color burst signal, passing said continuous oscillation signal; and timing pulse generating means (34) for generating a timing pulse of the same width as said period for controlling said switch means, thereby obtaining at an output of said switch means a chrominance signal with a duration expanded color burst signal.

Claim 3

Apparatus according to claim 1, wherein said continuous oscillation signal generating means comprises a phase-lock loop circuit (33) synchronised with frequency of the color burst signal.

Claim 4

Apparatus according to claim 2, wherein said continuous oscillation signal generating means further comprises a phase adjusting circuit (32) for adjusting the phase of the continuous oscillation signal.

Claim 5

Apparatus according to claim 2, wherein said phase-lock loop (33) is synchronised with the color subcarrier frequency.

Claim 6

Apparatus according to claim 2, wherein said phase-lock loop (33) is synchronised with the frequency of the low-frequency converted color burst signal.

Claim 7

Apparatus according to any one of the preceding claims, wherein the duration of the expanded color burst signal begins at the leading edge of the horizontal synchronising signal and ends at the end of the original color burst signal.

Claim 8

Apparatus according to claim 1, wherein the timing pulse generating means (34) is responsive to a horizontal synchronising signal for producing a first and second timing pulses; and the apparatus further includes a further switch (31) for passing a normal color burst signal in response to the first timing pulse; a phase adjusting circuit (32) for adjusting the phase of the normal color burst signal passed through said further switch (31); and a phase lock-loop circuit (33) coupled to said phase adjusting circuit for producing a continuous oscillation signal having the same frequency and phase as those of the normal color burst signal; the first-mentioned switch (35) normally passing the chrominance signal and, at a period including the normal color burst signal and longer than the duration of the normal color burst signal, passing the continuous oscillation signal from said phase-lock loop in response to said second timing pulse, thereby obtaining a chrominance signal with a duration expanded color burst signal.

Claim 9

Apparatus according to claim 7, wherein the timing and duration of said first timing pulse is the same as those of the normal color burst signal and said second timing pulse starts at the leading edge of the horizontal sychronising signal and ends at the end of the normal color burst signal.

Claim 10

Apparatus according to any one of the preceding claims, wherein said recording chrominance signal processing means further comprises a gain adjusting circuit (39) for adjusting the gain of the continuous oscillation signal from said phase-lock loop.

Claim 11

Apparatus according to claim 9, wherein said recording chrominance signal processing means further comprises an automatic color control circuit (40) for-keeping constant the level of the chrominance signal.

Claim 12

A magnetic recording/reproducing apparatus for recording a video signal onto a recording medium and reproducing the recorded video signal from the recording medium, comprising: a recording and reproducing magnetic head (10,11); means (22) for processing a recording luminance signal; means (24) for processing a reproducing luminance signal; means (23,26) for processing a recording chrominance signal; and means (25,27) for processing a reproduced chrominance signal; said recording chrominance signal processing means including a balanced modulator (7) for converting the chrominance signal to a low frequency chrominance signal; means (60) for producing a continuous oscillating signal having the same frequency as that of a color burst signal of the low-frequency converted chrominance signal; means (32,39) for adjusting the gain and phase of the continuous oscillating signal to be the same as those of the color burst signal of the low-frequency converted chrominance signal; a timing pulse generator (34) responsive to the horizontal synchronising signal for generating a timing pulse corresponding to a period including and longer than the duration of the burst signal of the low-frequency converted chrominance signal; and switch means (35) normally passing the low-frequency converted chrominance signal and, in response to said timing pulse, passing said continuous oscillation signal having the same gain and phase as those of the color burst signal of the low-frequency converted chrominance signal, thereby obtaining a low-frequency converted chrominance signal with a duration expanded color burst signal.

Claim 13

A magnetic recording/reproducing apparatus for recording a video signal onto a recording medium and reproducing the recorded video signal from the recording medium, comprising: a recording and reproducing magnetic head (10,11); means (22) for processing a recording luminance signal; means (24) for processing a reproducing luminance signal; means (23,26) for processing a recording chrominance signal; and means (25,27) for processing a reproduced chrominance signal; said recording chrominance signal processing means including a balanced modulator (7) for converting the chrominance signal to a low frequency chrominance signal; means (60) for producing a continuous oscillating signal having the same frequency as that of a color burst signal of the low-frequency converted chrominance signal; means (32,39) for adjusting the gain and phase of the continuous oscillating signal to be the same as those of the color burst signal of the low-frequency converted chrominance signal; a timing pulse generator (34) responsive to the horizontal synchronising signal for generating a timing pulse corresponding to a period including and longer than the duration of the burst signal of the low-frequency converted chrominance signal; and switch means (35) normally passing the low-frequency converted chrominance signal and, in response to said timing pulse, passing said continuous oscillation signal having the same gain and phase as those of the color burst signal of the low-frequency converted chrominance signal, thereby obtaining a low-frequency converted chrominance signal with a duration expanded color burst signal.

Claim 14

Apparatus according to claim 13, wherein said continuous oscillation signal producing means extracts the continuous oscillation signal from said balance modulator (7).

Claim 15

Apparatus according to any one of the preceding claims, wherein said reproduced chrominance signal processing means includes a muting circuit (27) for eliminating the expanded portion of the expanded color burst signal so as to obtain the normal color burst signal.

Claim 16

Apparatus according to any one of the preceding claims, wherein said recording luminance signal processing means (22) includes a filter circuit for limiting the frequency band of the luminance signal (50,51), and switch means (53,54) for allowing the luminance signal to pass said filter circuit (50,51) during a period corresponding to the duration of the expanded color burst signal.