Magnetic recording/reproducing apparatus with skew correction

Claim 2

A magnetic recording/reproducing apparatus, comprising: a plurality of magnetic means attached on the circumference of a rotary drum for recording video signals on a magnetic tape and picking up the video signals recorded on the magnetic tape by scanning the magnetic tape; means for driving said rotary drum and said magnetic tape so that the relative speed of said magnetic means and said magnetic tape is substantially constant; switching means for producing one video signal by switching the video signals picked up by said plurality of magnetic means; means for processing the one video signal produced by said switching means; switching point control means for controlling said switching means so that the switching point of said magnetic means by said switching means is included in a horizontal blanking period of said processed video signal; drop out detection means for outputting a drop out detection pulse by detecting the drop out of said video signal reproduced from said magnetic tape, compensation means responsive to said drop out detection signal for compensating for a part of said video signal utilizing said video signal preceding and succeeding the period, pseudo drop out signal output means for outputting a pseudo drop out signal similar to said drop out detection signal in synchronization with the switching of said magnetic means by said switching means; and gate means for finding a logical product of said drop out detection signal and said pseudo drop out signal and applying it to said compensation means.

Claim 3

The magnetic recording/reproducing apparatus according to claim 1, further comprising time base correction means for correcting the time base shifts included in outputs of said video signals and said gate means.

Claim 4

The magnetic recording/reproducing apparatus according to claim 2, wherein said time base correction means comprises: burst flag pulse generation means for detecting the burst signals of said video signal and generating a burst flag pulse; PLL means responsive to said burst flag pulse for outputting a first clock signal including a time base shift identical with said time base shift of said video signals; means responsive to changes in the values of said reference switching signal for temporarily restricting said PLL means to follow the time base shift of said video signals; and storage means for storing said video signal in synchronization with said first clock signal.

Claim 5

The magnetic recording/reproducing apparatus according to claim 3, further comprising: write start pulse generation means responsive to said burst flag pulse and said first clock signal for generating a write start pulse for defining the start timing of writing said video signals into said write means; pseudo start pulse generation mean responsive to said first clock signals for generating a pseudo start pulse in a prescribed relation with said first clock signal; switching means for usually selecting the output of said write start pulse generation means, selecting the output of said pseudo start pulse only in a predetermined period of time in response to a change in the value of said reference switching signal, and applying the output to said storage means as a signals defining the write start timing of said video signal.

Claim 6

A magnetic recording/reproducing apparatus, comprising: a plurality of magnetic means attached on the circumference of a rotary drum for recording video signals on a magnetic tape and picking up the video signals recorded on the magnetic tape by scanning the magnetic tape; means for driving said rotary drum and said magnetic tape so that the relative speed of said magnetic means and said magnetic tape is substantially constant; switching means for producing one video signal by switching the video signals picked up by said plurality of magnetic means; means for processing the one video signal produced by said switching means; switching point control means for controlling said switching means so that the switching point of said magnetic means by said switching means is included in a horizontal blanking period of said processed video signal; said switching point control means comprises: reference switching signal output means for outputting a reference switching signal which takes a first and a second values alternately in a cycle identical with that of the switching of said magnetic means in synchronization with the rotation of said rotary drum; means for outputting a first signal with a frequency and a phase identical with a frequency and phase of a horizontal synchronizing signal included in said one video signal; and means for latching the value of said reference switching signal in a timing determined based on said first signal, wherein said means for outputting the first signal comprises: horizontal synchronizing signal detection means for detecting the horizontal synchronizing signal included in said video signals; an AFC-H circuit for outputting a signal of a stable frequency having a phase identical to the phase of the horizontal synchronizing signal detected by said horizontal synchronizing signal detection means and having a frequency identical to the frequency of the horizontal synchronizing signal detected by said horizontal synchronizing signal detection circuit.

Claim 7

A magnetic recording/reproducing apparatus, comprising: a plurality of magnetic means attached on the circumference of a rotary drum for recording video signals on a magnetic tape and picking up the video signals recorded on the magnetic tape by scanning the magnetic tape; means for driving said rotary drum and said magnetic tape so that the relative speed of said magnetic means and said magnetic tape is substantially constant; switching means for producing one video signal by switching the video signals picked up by said plurality of magnetic means; means for processing the one video signal produced by said switching means; switching point control means for controlling said switching means so that the switching point of said magnetic means by said switching means is included in a horizontal blanking period of said processed video signal; said switching point control means comprises: reference switching signal output means for outputting a reference switching signal which takes a first and a second values alternately in a cycle identical with that of the switching of said magnetic means in synchronization with the rotation of said rotary drum; means for outputting a first signal with a frequency and a phase identical with a frequency and phase of a horizontal synchronizing signal included in said one video signal; and means for latching the value of said reference switching signal in a timing determined based on said first signal, wherein said means for outputting the first signal comprises: horizontal synchronizing signal detection means for detecting the horizontal synchronizing signal included in said video signals; an AFC-H circuit for outputting a signal of a stable frequency having a phase identical to the phase of the horizontal synchronizing signal detected by said horizontal synchronizing signal detection means and having a frequency identical to the frequency of the horizontal synchronizing signal detected by said horizontal synchronizing signal detection circuit.