摘要:
A clamp circuit includes a coupling capacitor (C1) connected between signal input (10) and signal output (12) terminals. A constant current sink (18) and a controlled current source (16) are connected to the output terminal. A comparator (14), coupled to the output terminal via a lowpass filter (R1, C2). generates signals for conditioning the controlled current source (16) to source current whenever the output terminal exhibits a potential which differs from a predetermined reference in a predetermined polarity sense.
摘要:
A digital D.C. control system includes a multiplexer (22), a digital-to-analog converter (24), a capacitor (30), offset generating circuitry (26,27,28) and clamping circuitry (33,34 or 42,44,46). A digital signal (from 20) to be D.C. controlled and a digital brightness control signal (from 16) are alternatively coupled by the multiplexer to the input of the digital-to-analog converter. The output from the digital-to-analog converter is coupled to a system output terminal via the capacitor. When the signal is applied to the digital-to-analog converter a fixed D.C. offset is applied to the interconnection of the converter and capacitor. During preselected intervals the D.C. control value is coupled to the digital-to-analog converter concurrently with the system output terminal being clamped (through 33 or 44) to a fixed reference and the D.C. offset circuitry being disabled (at 27). This combination of apparatus permits controlling the D.C. level of a digitally processed signal without affecting the dynamic range of the digital signal.
摘要:
A clamping circuit suitable for an image processing is disclosed. This clamping circuit includes a differential output circuit (13) to which an input signal is applied, series-connected two MOS type gate circuits (14,15) respectively having gate electrodes to which an output signal from the differential output circuit to be clamped and a reference voltage (V REF ) of a target value are applied, and reset circuit (18) including a holding capacitor (17) connected to the drain electrode side of either of the MOS type gate circuits (14,15) to discharge charge in the holding capacitor (17) at the time of beginning of clamping operation. The clamping circuit further includes a current source (16) connected to the junction between the MOS type gate circuits (14,15), charge current flow control circuit (19) for accumulating charge in the holding capacitor (17), and feedback circuit (20) for feeding back a potential of the holding capacitor (17) to the differential output circuit (13). Thus, a small-sized clamping circuit which can perform stable operation is provided.
摘要:
An image sensing apparatus having a conversion member for converting a radiation wave into visual light, an image sensing area having a plurality of pixels for converting the visual light converted by the converting member into an electric signal, and a shielding member mounted in a partial area of the image sensing apparatus for shielding the radiation wave.
摘要:
A clamp (18) combines a video signal, which may be a digitzed video signal, with a DC offset to clamp the back porch portion of the video signal to a predetermined level, for example, an IRE level. A divider responsive to the clamp generates a reference signal (BACK PORCH REF) having values indicative of IRE levels of the back porch portion prior to being clamped. In an adaptive sync slicer (20), a summer generates slice level values indicative of a numerical relationship, for example, an average, of the reference signal values and a fixed value; and, a comparator generates a composite synchronizing signal by comparing the video signal to the slice level values. A limiter may be used to restrict the range of the slice levels. The clamp, summer, comparator and limiter may be digital circuits.
摘要:
La présente invention concerne un circuit d'asservissement d'un signal analogique (Vc) sur une valeur de référence, comprenant un convertisseur analogique/numérique (12) recevant le signal analogique modifié par la charge stockée dans une capacité (C). Un comparateur numérique (14') reçoit la sortie du convertisseur et une valeur numérique de référence (Nref), et commande des sources de charge (Ic) et de décharge (Id) de la capacité. Un point mémoire représente un drapeau de condition de stabilité pour inhiber la charge et la décharge de la capacité. Un circuit (14', 16) d'analyse de la sortie du convertisseur active le drapeau lorsque les valeurs successives (N) de la sortie du convertisseur satisfont à une condition de stabilité prédéterminée, et désactive le drapeau lorsque les valeurs successives de la sortie du convertisseur satisfont à une condition de divergence prédéterminée.