×

Field-transfer CCD imagers with reference-black-level generation capability

  • US 4,498,105 A
  • Filed: 05/27/1982
  • Issued: 02/05/1985
  • Est. Priority Date: 05/27/1982
  • Status: Expired due to Term
First Claim
Patent Images

1. In a charge-coupled-device imager of the field transfer type, having an A recister of parallel charge transfer channels for accumulating packets of charge at pixel sites responsive to the illumination of the charge transfer channels in said A register during integration times, having a B register of parallel charge transfer channels preceded in cascade connection by respective ones of the parallel charge transfer channels in said A register, to which charge transfer channels in the B register said packets of accumulated charge are transferred from said A register during field transfer times between said integration times, and from which charge transfer channels in said B register successive lines of those charge packets are clocked forward a line at a time during said integration times, having a C register functioning as a parallel to serial converter for successive lines of each field as they are clocked forward from the B register, thereby to form a video signal;

  • and having means for shielding the B and C registers from illumination, the improvement for generating a reference-black-level sample in each line of said video signal responsive primarily to integrated dark currents alone and not appreciably to charges generated by photoconversion, comprising;

    at least one further charge transfer channel being shielded from illumination, being of equal length with each of the charge transfer channels in said B register, being clocked in synchronism with the charge transfer channels in said B register and having a final stage connected to supply to said C register charge packets representative of said reference-black-level samples which charge packets are generated at least in part by accumulation of dark current in said at least one further charge transfer channel,

View all claims
  • 1 Assignment
Timeline View
Assignment View
    ×
    ×