Magnavox Government and Industrial Electronics Company

Magnavox Consumer Electronics Company

Ernest F Close

Horizontal and vertical deflection windings in a deflection yoke coil assembly of a CRT (cathode ray tube) having stroke written or raster scan displays are driven by x and y analog deflection signals, respectively. Each of the x and y analog deflection signals are converted to x and y digital signals, respectively, sampled to provide x, y sample sets which are coupled to a digital x correction signal memory and a digital y correction signal memory, respectively. Geometric corrections are stored in the memories for each of a predetermined number of x, y signal set values which correspond, respectively, to a number of point locations over the CRT screen. The x and y corrections that are addressed from the memories are supplied to MDACs (multiplying digital to analog converters) and then to analog delay line filters which supply the x, y analog correction signals for summing with the x, y analog deflection signals, respectively. The x and y digital signals are also coupled to separate astigmatism, dynamic focus, shading and convergence memories which are coupled to DACs (digital to analog converters) and then to respective CRT controls or associated circuitry.

Display control apparatus

The output of a deflection operational amplifier is coupled through a dissipation circuit to a deflection yoke coil of a stroke written cathode ray tube for deflecting an electron beam on the tube screen. A feedback circuit is coupled between the coil and the inverting input of the amplifier to control the current through the coil. The dissipation circuit comprises a dissipative resistor, such as an incandescent lamp, and a shunt connected bypass capacitor. The dissipation circuit dissipates power during coil steady current conditions such as exist during slow movement or hold of the electron beam on the screen when voltage across the coil is low but coil current may be high. Thus the power otherwise dissipated in the amplifier output transistors is dissipated in the dissipation circuit. The bypass capacitor passes high frequency deflection signals to the coil during coil high instantaneous current conditions corresponding to fast movement or slewing of the electron beam on the tube screen.

Amplifier dissipation divertor circuit

The method and apparatus for providing an AM stereo receiver suitable for receiving an AM/PM modulated RF carrier frequency, the receiver uses a standard AM detector to receive said AM/PM modulated intermediate frequency and to provide an 1+r signal. The stereo detector system further provides an 1-r signal and comprises means (104) for receiving and limiting the amplitude of the AM/PM modulated signal to eliminate the amplitude modulation therefrom and for providing a signal having phase modulation only. The limited AM/PM signal from limiter (104) is then provided to an FM quadrature detector (106) for recovering any PM signal. The PM signal detected and provided by said FM quadrature detector (106) is then integrated by an integrator (124) to provide a true PM signal. The output of integrator (124) is provided to a squelch gate (128) and to a means for sampling and determining the presence of a 5 Hz signal. The means for sampling and determining comprises a 5 hz band pass filter (130), a squaring circuit (132) and a missing pulse detector (134). The squelch gate (128) receives a control signal from missing pulse detector (134) along with the 1-r signal from integrator (124). The 1-r signal then passes through squelch gate (128) in response to the presence of the control signal which indicates a stereo broadcast. The output from squelch gate (128) which is the 1-r signal is then combined with the 1+r signal from the standard AM detector by a matrix (102) to provide a true L and a true R signal for a stereo AM broadcast.

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Fort Wayne, IN, United States of America

Ernest F Close