Abstract: Output signal samples provided from a solid-state imager, responsive to dark current accumulated in its CCD registers, are supplied to circuitry for measuring dark current noise level. The measured level is compared to a reference value for generating an error signal controlling the application of power to a thermoelectric cooler cooling the solid-state imager. The imager is cooled sufficiently to reduce dark current generation. A servomechanism for keeping dark current level acceptably low with minimal power consumption by the thermoelectric cooler is thus provided.

Abstract: Low frequency streaking noise which is effected by modulating the black reference with high frequency noise is eliminated from the displayed picture in a television system by switching the signal during the horizontal blanking interval to a noise-free black reference. A CCD or other imagers where a pixel-by-pixel reference is available provide a unique opportunity to eliminate low frequency streaking in the video display. Each pixel of a solid state imager includes a black level reference. In accordance with the invention, a switch circuit is added to a correlated double sampling system used in conjunction with a CCD imager. During the horizontal blanking interval the switch is rendered conductive to substitute a noise-free reference derived from the pixel clamp.

Abstract: Output signal samples from a solid-state imager, responsive to dark currents accumulated therein, are applied to slope responsive circuitry for generating a signal which can be used, for example, for field shading correction or imager temperature control. Dark current slope responsive measuring circuitry is particularly advantageous over prior dark current measuring circuitry since it is uneffected by DC offset of the dark current signal which results from imager mask misregistration or carrier diffusion when receiving radiant energy.

Abstract: In a plural-level gate metallization CCD shift register the clocking voltages applied to the levels are automatically supplied differential offset biases to cause the potential wells to have uniform depth. The differential offset biases are developed responsive to the differences in the threshold voltages of insulated-gate field effect transistors integrated on the same semiconductor substrate as the CCD shift register so as to have their gate electrodes in the different levels of gate metallization.

Abstract: At low light levels, the floating diffusion output stage of a CCD imager has the peaks of the reset pulses applied to its reset gate reduced. This introduces spatial integration in the direction of line scan that improves the signal-to-noise ratio of the video samples supplied as imager output.

Abstract: A video signal originating from a field-transfer CCD imager exhibits field shading attributable to integrated dark currents. A compensating waveform is generated and linearly combined with the video signal to suppress that field shading.

Abstract: Three embodiments of an improved smear reduction technique, for reducing substantially all the smear in a CCD field-transfer imager system due to the presence of a bright spot in the projected image, regardless of whether the bright spot remains fixed or whether the bright spot moves between successive field periods. Prior smear reduction techniques were not effective with respect to a moving bright spot. Structurally the improved system employs a CCD field-transfer imager including a line register, in addition to conventional A and B, for collecting smear charge produced in the A register during each successive field period. The smear line register cooperates with associated circuitry to provide the improved smear reduction. In a first and second of the three embodiments, the imager includes a conventional C line register for deriving a smeared video output applied as an input to the associated circuitry, and the smear line register is an additional line register, known as the D register.

Abstract: A CCD imager is made to have an internal drift field tending to force further into the bulk any charge carriers outside the potential wells induced adjacent to integrating electrodes, so those charge carriers recombine in the bulk. This reduces background striations, reduces crosstalk, can be used for improving blooming control, and can be exploited to control the wavelengths of light to which the imager is responsive.

Abstract: Color signal samples generated by CCD imagers used with a color stripe filter normally exhibit hue errors owing to cross-color components in the samples arising from misalignment of the color striped imager on the imager elements. These cross-color components are suppressed in the invention, by re-sampling the color signals.

Abstract: Output signals are derived from two portions of a CCD imager. The first output signal is derived from a drain diffusion in the form of a signal current and applied to an amplifier with poor high frequency S/N due to needed high frequency peaking. The second output signal is derived from a floating diffusion (or floating gate) through an on-chip MOSFET amplifier which has a poor low frequency S/N due to 1/f noise. The first and second output signals are filtered through complementary LPF and HPF respectively and then combined together.

Abstract: CCD devices, such as imagers, typically have built in MOSFET output amplifiers with a large amount of l/f noise. Instead of using the baseband video output signal, the present invention uses video signal sidebands centered about the C-register clock frequency or a harmonic thereof for improved S/N. An integrator and a gate are used to still further improve the S/N.

Abstract: Color signal samples generated by CCD imagers used with a color stripe filter normally exhibit hue errors associated with misalignment of the color striped imager on the imager elements, which errors are obtrusive to the viewer of a TV display based on those color signal samples. These hue errors are converted to less-obtrusive color saturation and luminance errors in accordance with the invention, by re-sampling the color signals.

Abstract: A gradient in the impurity concentration of the semiconductor material in a CCD imager, normal to the surface in which the charge-accumulation wells are induced, speeds the collection of charge carriers formed further from the surface by photon interaction with the semiconductor lattice. This reduces the chance for crosstalk between charge-accumulation wells owing to sideways diffusion.

Abstract: The present circuit is applicable to buried channel charge coupled devices (CCD's) of the type having an input circuit which employs a "skimming" technique for producing a charge representing an input signal. A given amount of charge initially is present in an input potential well of the CCD and an amount of charge representing an input signal is skimmed therefrom for propagation down the CCD, leaving behind a residual charge which continuously remains in the input potential well. The gain of the input circuit of the CCD is controlled by controlling the amount of this residual charge either in open loop fashion or by means of feedback. A comb filter suitable for separating the luminance and chrominance components of a television signal which includes this circuit is also described.

Abstract: Real time detection of defective picture sampling elements of a high resolution imager may be achieved by (1) imaging a scene by means of low resoluting power imaging optics to produce an image resolution limit spot size on the imager which is large relative to the center-to-center pitch distance of the picture sampling elements, and (2) indicating as spurious each single picture sample of the serial output from the imager that exhibits certain discriminating contrast characteristics with respect to its neighboring picture samples. This permits a spurious sample to be corrected by replacement with an interpolated value derived from its neighboring samples.

Abstract: In a CCD imager of the single-layer electrode type wherein the gate electrodes are of one conductivity and the "gaps" between electrodes are of opposite conductivity type, sparkle and mottling are reduced by controlling the conductivity of the gaps. Such control is achieved by employing an overlying control electrode which is insulated from the gaps and gate electrodes, to which an adjustable control voltage is applied. The latter can be derived in open-loop fashion; however, in a preferred form of the invention, the leakage current between a pair of adjacent electrodes is sensed and employed to control a voltage which is fed back to the control electrode.

Abstract: The present invention is applicable to a CCD imager of the field transfer type employing a single layer electrode structure comprising gate electrodes formed of semiconductor material of one conductivity type separated from one another by semiconductor material of opposite conductivity type. Sparkle is reduced by DC biasing the electrodes in the B register driven by at least one of the multiple phase voltages.

Abstract: A "fill and spill" charge coupled device (CCD) input circuit in which the source electrode is clamped to a voltage level (V.sub.T +.DELTA.V) lower than that of the input gate electrode during the fill operation, where (V.sub.T +.DELTA.V) is the gate-to-source voltage of a field effect transistor during conduction. The field effect transistor and input gate electrode are integrated onto the same semiconductor substrate and therefore exhibit the same threshold voltage V.sub.T so that the difference between the surface potential at the source electrode and the surface potential beneath the input gate electrode is independent of V.sub.T.

Abstract: A "fill and spill" charge coupled device (CCD) input circuit which includes a drain region separated from the input storage region by a potential barrier. The barrier height is held at a level at least as high as that of the potential barrier beneath the first gate electrode and lower than that of the first transfer electrode to insure that carriers injected by the source electrode during the fill operation which might otherwise flow down the CCD channel pass instead to the drain region.

Abstract: Comb filter which includes a first CCD delay line for imparting a delay equal to one horizontal line time plus the delay inserted by N additional stages and second and third CCD delay lines, each having N stages. Video signal is applied to the first and second delay lines and its complement to the third delay line. The gains of the second and third CCD delay lines are controlled to make them equal to that of the first CCD delay line to control the depth of the rejection notches of the filter to desired levels. In one embodiment, feedback from the output of the first and second lines is employed to control the gain of the second line and feedback from the output of the first and third lines is employed to control the gain of the third line. In another embodiment, the respective gains are controlled in open loop fashion by controlling the residual charge in the input storage well of CCD's operated in the skimming mode.