Admiral Corporation

Other

Dennis W Rhee

Gopal Krishna Srivastava

A television receiver is disclosed including a varactor-type tuner selectively coupled to a synthesizer. Illustratively, the synthesizer includes a keyboard for selecting the desired channel within the UHF or VHF band, a channel memory for receiving and storing the selected channel and a programmable divider which divides selectively the output of the tuner's local oscillator in accordance with the selected channel to generate and apply its output to a phase comparator. The output of a reference oscillator also is applied to the phase comparator, whereby the output of the programmable divider is mixed therewith to obtain a tuning voltage to be applied to the tuner, which is associated with an automatic fine-tuning circuit (AFT); the AFT is adapted to be detuned selectively to increase the amplitude of the picture carrier signal and therefore, enhance the quality of the displayed images for weak signals, such as received from distant stations.

Selectively coupled synthesizer for tuner of TV receiver

A single, combined contrast/brightness control is disclosed herein for a television receiver. A contrast control in the form of a variable potentiometer, is coupled to the output, driver transistor of the video amplifier, which serves to amplify and apply the video signal to the cathode ray tube (CRT) and including AC/DC coupling in the form of a resistor and a capacitor. The DC coupling resistor sets the DC bias level to the output transistor and in particular to its base at a level dependent upon the DC level established across the constrast/brightness control potentiometer. Further, the AC coupling capacitor is selectively charged to further adjust the DC bias of the output transistor to a level with the DC coupling resistor whereby the black level of the output signal applied to the cathode ray tube is maintained relatively constant with regard to a predetermined level. In a preferred embodiment of this invention, the predetermined level is the sync tip and back porch voltages and the charging of the AC coupling capacitor is carried out during the horizontal retrace cycle, at which time a charging circuit is formed through the capacitor whereby it is charged to a potential dependent upon the setting of the contrast control potentiometer, and thus, the bias level to the base of the output transistor is adjusted to set the black level to a predetermined level. In this manner, it is only necessary to use the single contrast/brightness control to set both the contrast and the brightness level of the displayed image upon the CRT.

Combination contrast/brightness control for a television receiver

An automatic hue control circuit is disclosed for a color television receiver, wherein the flesh-tone signals of the reproduced image are enhanced by spreading the phase angle between the R-Y and the B-Y reference signals before applying them to their respective demodulators. In one aspect of the invention, the flesh-tone enhancement by phase-shifting the R-Y and B-Y signals occurs only for positive values of the flesh-tone signals. In a further aspect of this invention, a simplified automatic hue control circuit is disclosed as comprising a matrix for receiving, respectively, the R-Y, the G-Y and the B-Y color signals to obtain a DC quiescent voltage with which the flesh-tone signal, as indicated by the sum of the R-Y and the G-Y signals, is compared to render conductive a switch, illustratively in the form of a diode, whereby the phase-shift is imparted to the R-Y and B-Y reference signals. In particular, the desired phase shift between the R-Y and B-Y signals is effected only when the flesh-tone signals are of a positive value, whereby a more accurate color reproduction is provided.

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Palatine, IL, United States of America

Dennis W Rhee