Video tape recorder having picture-in-picture function

Claim 1

A video tape recorder capable of producing sub-picture of video signals to be edited, comprising: means for reproducing video signals recorded on a tape; means for recording video signals on said tape; video signal input means for receiving input video signals and supplying the input video signals to said recording means; switch means for selecting video signals from said reproducing means and said video signal input means, respectively; analog-to-digital converter means for converting video signals selected by said switch means to digital video signals; first and second memory means each capable of storing a predetermined quantity of said digital video signals selected from a field and a frame thereof; digital-to-analog converter means for converting signals read from each of said first and second memory means to analog video signals; monitor means having a screen; address control means for controlling writing and reading addresses of said memory means so as to read from said memory means sub-picture signals which are to be supplied to said monitor means for display on said screen; key means actuable for establishing an editing mode of said video tape recorder and for selecting an operation mode of said video tape recorder from among playback, playback-pause, recording and recording-pause modes thereof; and system control means for controlling said reproducing means, said recording means, said switch means and said address control means, said system control means being programmed as follows; with said video tape recorder in said editing mode, a) When said key means is actuated to selected one of said playback and playback-pause modes, said switch means selects video signals from said video signal reproducing means, and said address control means causes reproduced video signals from said tape to be written in said first memory means and then read from said first memory means so that said sub-picture signals correspond to said reproduced video signals; b) When said key means is actuated to selected said recording-pause mode, said switch means selects the video signals from said video signal input means, and said address control means causes said video signals from said video signal input means to be written in said second memory means and then read from said second memory means so that said sub-picture signals correspond to said video signals from said input means; and c) When said key means is actuated to select said recording mode, said switch means selects the video signals from said video signal input means, and said address control means causes said video signals from said video signal input means to be written alternately in one of said first and second memory means and then causes reading from said first and second memory means so that sub-picture signals corresponding to said video signals from said input means are obtained from said first and second memory means, respectively.