摘要:
A composite video signal each line of which comprises a line synchronising pulse, a front and a back porch and a vision portion, the synchronising pulse of which may contain a burst of pulsed additional information is applied to an input terminal (1) which is connected to the input of a first signal path (T1, T2) whose output is connected to a current source (I1) and to an output terminal (8). A second signal path (T3, T4) has its input connected to a reference voltage input (5) and its output connected to the current source (I1) and the output terminal (8). A switching circuit (T5, T6) alternately enables the first and second signal paths (T1, T2; T3, T4) under the control of a switching signal at a connection (10) such that the output terminal (8) produces a composite video signal in which the synchronising pulse at the input terminal is replaced by a pulse or level. The replacement does not contain the burst of pulsed additional information when present in the applied signal.
摘要:
The present invention provides a direct current restorer applied to a pedestal clamp circuit of a television receiver or the like, in which an input video signal is compared with a pedestal level setting reference signal for every pedestal period, and, based on difference between the pedestal level of the input video signal and the level of the reference signal, the direct current level of the input video signal is shifted. In this direct current restorer, a direct current according to the level variation of the reference signal may be superposed on the input video signal so that the direct current level of the input video signal is corrected according to the level variation of the reference signal. Accordingly, when adjusting the pedestal level or achieving a liquid crystal display in which the polarity of the input video signal is periodically inverted, a direct current according to the level variation of the reference signal may be superposed on the input video signal. Thus, the pedestal level of the input video signal may quickly follow the level variation of the reference signal and may be controlled to the level of the reference signal with no influence exerted onto the comparison in level of the input video signal with the reference signal. Accordingly, when this direct current restorer is applied to, for example, a drive circuit for a liquid crystal panel such as a liquid crystal television receiver or the like in which the input video signal is periodically changed in polarity, a stable direct current restoration may be achieved.
摘要:
Zur Wiederherstellung des Gleichspannungswertes bei Videosignalen wurde bisher eine Signalabtastung und eine Aufintegration vorgenommen. Während der Video-Klemmperiode wurde der Referenzwert gehalten. Zur Wiederherstellung des Gleichspannungswertes von Videosignalen wird nun ein Transkonduktanzverstärker (TCA) verwendet, dessen Spannung zur Arbeitspunkteinstellung (Bias) im Takt von Video-Klemmimpulsen (KL) umgeschaltet wird. Das Ausgangssignal des Transkonduktanzverstärkers (TCA) wird einem Haltekondensator (HC) zugeführt, aufintegriert (IG) und als Gegenkopplungssignal für den Transkonduktanzverstärker (TCA) verwendet. Die Trägerverwischung von Videosignalen läßt sich um mehr als 55 dB, und niederfrequente Störsignale wie Brummanteile in der Grundfrequenz lassen sich um mehr als 40 dB unterdrücken.
摘要:
Bei der Satellitenübertragung von Fernsehsignalen wird dem zu übertragenden Signal vor der Frequenzmodulation ein sog. Verwischungssignal überlagert. Dieses Verwischungssignal verursacht im Satelliten-Fernsehempfänger unerwünschte Helligkeitsänderungen und Störungen bei der Synchronisierung. Diese werden nach der vorliegenden Erfindung vermieden, indem aus den Synchronsignalspitzen des demodulierten Satelliten-Fernsehsignals eine analoge Regelspannung gewonnen und dem störbehafteten Signal hinzuaddiert wird. Die Abtastung der Synchronsignalspitzen erfolgt in einem Zeitintervall, dessen Dauer höchstens gleich der Dauer der Vor- bzw. Nachtrabanten des Videosignals ist. Damit können auch während der vertikalen Austastlücke korrekte, die Amplitude des Verwischungssignals kennzeichnende Abtastwerte gewonnen werden.
摘要:
In a wideband video signal processing system, a video signal is capacitively (18) coupled to a kinescope via a signal path. A video signal clamping diode (22) is coupled from the video signal path to a low impedance point (B) in a feedback path of a keyed switching transistor (31). Parasitic capacitances (CP, CP1, CP2) associated with the clamping diode (22) and/or with the output of the switching transistor (31) are decoupled from the video signal path by means of a first decoupling resistor (24), and/or a second decoupling resistor (37) included in the feedback path, respectively.
摘要:
A wideband video signal processing system includes a blanking interval signal conditioning circuit (14) with reduced parasitic capacitance. The circuit comprises an AC coupling capacitor (17) between the input and output of a video signal path, preferably between an input buffer amplifier (15) and an output buffer amplifier (19). A first keyed electronic switch (16) of the single pole, single throw type is coupled in series with the capacitor. A second keyed electronic switch (18) of the single pole, single throw type is coupled between the output of the capacitor and a reference voltage. The first and second switches are keyed to establi sh a fixed video signal reference value during image blanking intervals.
摘要:
@ Die Erfindung betrifft eine Schaltungsanordnung zur Erzeugung von Klemmimpulsen für eine Klemmschaltung zur Wiedergewinnung der mittleren Bildhelligkeit eines Videosignals. Hierzu werden mittels einer Abschneidestufe (6) die Synchronimpulse vom Videoignal getrennt und zwei Monoflops (71, 72) zugeführt. Aus den Videosignalimpulsen werden zeilenfrequente Taktimpulse erzeugt und mittels einer von den Monoflops (71, 72) angesteuerten Zählschaltung (9) wird die vertikale Austastlücke erkannt. Diese Zählschaltung (9) wählt jeweils einen von zwei Ausgängen einer weiteren Zählschaltung (8) an, an denen zu unterschiedlichen Zeiten Klemmimpulssignale abgegeben werden.
摘要:
The invention relates to an image sensor system which includes an image sensor (CCD). The image from the image sensor is read out as a video signal. In addition to image values, the video signal also contains electrical and optical black noise. Black noise removal from the video signal is based on read out additional pixels that do not directly originate from image pixels to avoid clipping during clamping and analogue-to digital conversion. Furthermore, the image sensor system performs power control for the image sensor output amplifier to reduce unnecessary image sensor heating during image exposure. Particularly during long exposure unwanted sensor heating results in increased and unequally distributed black noise that can be lowered by reducing power consumption of the sensor output amplifier which is only used during reading out pixels but not needed during image exposure. To reduce amplifier power consumption during image exposure periods the system performs current control of the amplifier output stage.