DC Coupled, wide band width high voltage modulator
AssigneeMotorola, Inc.
InventorsRobert H. Bickley, Michael J. Dewey
Life of this patent
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Abstract
Apparatus for controlling the intensity of a display on a cathode ray tube wherein the control signals are DC through several megahertz and a control loop maintains the average value of the control signal on the grid of a cathode ray tube relatively constant. Low frequency and high frequency signals are applied to the tube through separate circuits which are coupled together to provide coincident high pass and low pass -3 db crossover points so that all control signals applied to the tube are substantially equal over the entire bandwidth.
Claims13
A modulator for controlling the intensity of a display on a cathode ray tube by means of signals including a DC intensity level component and AC components, said modulator comprising:
- (a) monitoring means associated with the cathode ray tube for sensing control voltages applied to the cathode ray tube;
- (b) optical isolator means having a relatively low voltage, control input signal and a relatively high voltage control output signal coupled to the cathode ray tube for producing a desired intensity;
- and
- (c) a control loop including comparator means coupled to said monitoring means and said optical isolator means for comparing the DC intensity level component and relatively low frequency AC components to the sensed control voltage applied to the cathode ray tube and supplying the control input signal to said optical isolator means maintaining the intensity of the cathode ray tube at the desired level.
A modulator for controlling the intensity of a display on a cathode ray tube by means of signals including a DC intensity level component and AC components, said modulator comprising:
- (a) a high frequency circuit for coupling the AC components to the cathode ray tube;
- (b) a DC/low frequency circuit for coupling the DC intensity level component to the cathode ray tube;
- and
- (c) apparatus common to both circuits and coupling said circuits so that the corner frequency in the DC/low frequency circuit and the corner frequency in the high frequency circuit are substantially equal.
Apparatus for controlling the high voltage on a cathode ray tube by means of signals including a DC level component, said apparatus comprising:
- (a) monitoring means associated with the cathode ray tube for sensing control voltages applied to the cathode ray tube;
- (b) optical isolator means having a relatively low voltage, control input signal and a relatively high voltage control output signal coupled to the cathode ray tube for producing a desired high voltage;
- and
- (c) a control loop including comparator means coupled to said monitoring means and said optical isolator means for comparing the DC level component to the sensed control voltage applied to the cathode ray tube and supplying the control input signal to said optical isolator means maintaining the high voltage applied to the cathode ray tube at the desired level.
Dependencies are inferred from the claim text.