North American Philips Consumer Electronics Corp.

Magnavox Consumer Electronics Company

James E Hitchcock

Kenneth R Skinner

Patrick M Rafter

A conventional peaking signal derived by delaying the incoming video or luminance signal first by one horizontal line delay and then by a second horizontal line delay is modified by multiplication with an adaptive factor. The adaptive factor is derived by first taking the difference between the incoming signal and the twice delayed signal, then deriving the magnitude or the square of this difference and multiplying this by a factor K empirically derived for the particular display device. The resultant signal is then subtracted from unity. This yields the factor by which the conventional peaking signal is multiplied. The conventional signal multiplied by this factor constitutes the final peaking signal which is added to the 1H delayed luminance signal to yield the desired peaked luminance signal.

Method and apparatus for generating an adaptive peaking signal

The edges of an incoming video signal are sharpened by switching the output furnishing the sharpened signal in sequence first to receive a signal delayed by a greater amount, i.e. a signal which has not as yet undergone transition, and, secondly, to receive a signal delayed by a lesser amount, i.e. one that has already completed the transition. The rise time of the affected edge thus depends only on the time required to switch from one terminal to the next. The same switching sequence is carried out regardless of whether the transition is a negative going or positive going transition.

Method and apparatus for improving the rise and fall time of a video

A nonlinear edge peaking system (10) is provided which reduces the rise and fall times of input signal transitions and prevents the introduction of excessive preshoot and overshoot. The system (10) includes a first circuit (76) which delays the input signal. A second circuit (48) which is connected in parallel with the first circuit produces an output which is the approximation of the absolute value of the widened second derivative having a preselected offset bias. A third circuit (42) connected in parallel with the first and second circuit produces at its output a delayed first derivative of the input signal. The combination of the output of the second and third circuit is differentiated, amplified, inverted and added to the delayed input signal producing a peaked or enhanced signal with reduced rise and fall times.

Nonlinear edge peaking system and method

An improved tuning system for a color television receiver embodying a varactor tuner having a controller functioning as a potentiometer to provide a preselected tuning voltage for channel selection. The system includes a tuning voltage supply having a low impedance drive which is serially connected at its output with the controller. The voltage supply applies a preselected source voltage to the controller which is substantially independent of changes in the resistive value of the controller. The tuning voltage supply is combined with automatic fine tuning correction circuitry connected between the automatic fine tuning system and the varactor tuner. The automatic fine tuning correction circuitry applies a correction voltage to the varactor tuner for temperature compensation, fine tuning errors of 500 KHZ or less, etc.

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Knoxville, TN, United States of America

James E Hitchcock