Television camera automatic beam alignment

Claim 2

In a television camera of the type having a cathode ray tube including target means for electrical representation of a video image, means for directing a cathode ray beam to said target means, means for producing an electrical representation of a fixed video test image at said target means and including a test card having a predetermined pattern of light and shade which presents an abrupt change in light and shade in the television field direction, beam alignment means for aligning the cathode ray beam of said tube at least in the television field direction, beam focusing means for providing variable beam focusing, means for deflecting said cathode ray beam to scan said target means at predetermined line and field frequencies, and means for producing video output signals representative of said fixed video test image during successive scanning deflections of said cathode ray beam, the combination of: detecting means connected to said means for producing video output signals for producing during different field periods of scanning an output signal when said cathode ray beam first encounters that portion of said electrical representation of the video test image corresponding to said abrupt change in light and shade therein; means for modulating said beam focusing means to vary the beam focusing thereof so that the number of television lines scanned before said detector means produces an output signal may vary in the event of beam misalignment in the field direction; reversible counter means connected to said means for deflecting for counting in opposite directions during a pair of said different field periods and having an output in response to any difference in such counts; control means connected to the output signal of said detecting means for causing said reversible counter means to count the number of television lines scanned before the detector means produces an output signal during said pair of different field periods; and means connected to the output of said reversible counter means for automatically adjusting said beam alignment means to align said beam in the field direction whereby the number of television lines scanned before said detecting means produces an output signal is the same during subsequent different field periods.

Claim 3

In combination with a television camera of the type having a cathode ray tube iNcluding target means for electrical representation of a video image; means for directing a cathode ray beam to said target means; means for producing an electrical representation of a fixed video test image to said target means in which the fixed video test image is a predetermined pattern of light and shade having boundary lines extending in the field and line directions; first beam alignment means for aligning the cathode ray beam in the television field direction; second beam alignment means for aligning the cathode ray beam in the television line direction; means for deflecting said cathode ray beam to scan said target means; beam focusing means for providing variable beam focusing; first pulse output means for producing an output at line frequency and connected to said means for deflecting to control scanning of the target means in the line direction at said line frequency; second pulse output means for producing an output at field frequency and connected to said means for deflecting to control scanning of the target means in the field direction at said field frequency; video output means for producing video output signals during successive scanning deflections of said cathode ray beam; and means connected to said second pulse generator means and said beam focusing means for modulating said beam focusing means to vary the beam focusing during successive field periods; the combination of: reversible counter means for producing beam alignment output signals; gate means connected to said first pulse output means for selectively passing the pulse output thereof to said counter means; frequency divider means connected to said second pulse output means for reversing the direction of count of said counter means during said successive field periods; further frequency divider means connected to the first frequency divider means for resetting said counter means to zero after each reversible count thereby during said successive field periods; level detector means connected to the output of said video output means for producing an output having a first pulse during each field period upon occurrence of said boundary line extending in the line direction and a further pulse during each line period upon the occurrence of said boundary line extending in the field direction; control means connected to the output of said second pulse output means and to the output of said level detector means for controlling said gate means to pass said output of the first pulse output means only during those portions of said successive field periods from the beginnings thereof until said first output pulse appears from said level detector means; and means for applying the output signal of said reversible counter means to said first beam alignment means after the counts thereby during said successive field periods.

Claim 4

In combination with a television camera of the type having a cathode ray tube iNcluding target means for electrical representation of a video image; means for directing a cathode ray beam to said target means; means for producing an electrical representation of a fixed video test image to said target means in which the fixed video test image is a predetermined pattern of light and shade having boundary lines extending in the field and line directions; first beam alignment means for aligning the cathode ray beam in the television field direction; second beam alignment means for aligning the cathode ray beam in the television line direction; means for deflecting said cathode ray beam to scan said target means; beam focusing means for providing variable beam focusing; first pulse output means for producing an output at line frequency and connected to said means for deflecting to control scanning of the target means in the line direction at said line frequency; second pulse output means for producing an output at field frequency and connected to said means for deflecting to control scanning of the target means in the field direction at said field frequency; video output means for producing video output signals during successive scanning deflections of said cathode ray beam; and means connected to said second pulse generator means and said beam focusing means for modulating said beam focusing means to vary the beam focusing during successive field periods; the combination of: reversible counter means for producing beam alignment output signals; gate means connected to said first pulse output means for selectively passing the pulse output thereof to said counter means; frequency divider means connected to said second pulse output means for reversing the direction of count of said counter means during said successive field periods; further frequency divider means connected to the first frequency divider means for resetting said counter means to zero after each reversible count thereby during said successive field periods; level detector means connected to the output of said video output means for producing an output having a first pulse during each field period upon occurrence of said boundary line extending in the line direction and a further pulse during each line period upon the occurrence of said boundary line extending in the field direction; control means connected to the output of said second pulse output means and to the output of said level detector means for controlling said gate means to pass said output of the first pulse output means only during those portions of said successive field periods from the beginnings thereof until said first output pulse appears from said level detector means; and means for applying the output signal of said reversible counter means to said first beam alignment means after the counts thereby during said successive field periods.

Claim 5

In the combination as defined in claim 2 including: pulse generator means for producing a pulse output to said counter means which is of frequency higher than said line frequency; control means connected to the output of said level detector means and to the output of said first pulse output means for controlling said pulse generator means to produce outputs to said counter means only during those portions of successive second field periods other than the first successive field periods from the beginning of successive lines until said further pulses appear from said level detector means; and means for applying the output signal of said reversible counter means to said second beam alignment means after the counts thereby during said second field periods.