Rca Inc.

Honeywell G.m.b.h.

David W Luz

Donald Henry Willis

John Charles Peer

Hugh F Sutherland, Ii

Peter E Haferl

Lawrence A Booth

Ronald E Fernsler

Jeffery B Lendaro

Alan Anderson Hoover

James E Hicks

James K Rinehart

Robert J Vitello

George C Waybright

Leslie N Thibodeau

James A McDonald

Roger E Wiegel

A processor controlled fluorescent lamp dimmer circuit is shown for use in an aircraft display system utilizing a fluorescent lamp in the backlight system of individual LCD display devices. By use of a processor control dimming circuit in control over each LCD display, greater flexibility, e.g., as by adjustment in software parameters, is made possible in the operation of a dimmer control circuit. The dimmer control circuit reacts to such conditions as ambient light within the aircraft cockpit, fluorescent lamp light energy output, and fluorescent lamp temperature to provide substantially consistent actual and perceived luminance on the LCD display as a function of such detected conditions. Furthermore, the processor control achieves the desired luminance without over-driving, and therefore deteriorating, the lamps. As a result, the pilot of the aircraft enjoys a more reliable and consistent LCD display and need not be distracted by variation in luminance of the LCD display in operation of the aircraft.

Processor controlled fluorescent lamp dimmer for aircraft liquid crystal

Line and field deflection circuits generate line and field deflection currents in respective line and field deflection windings to scan a raster on the phosphor screen of a square-planar picture tube having an aspherical faceplate. The asphericity of the faceplate subjects the scanned raster to gullwing distortion. A gullwing distortion correction circuit is responsive to signals repeating at line and field rates, respectively, for modulating the field deflection current during a line deflection period within the field deflection trace interval in a manner that corrects gullwing distortion of a corresponding raster scan line.

Gullwing distortion corrected deflection circuitry for a square-planar

A television deflection apparatus includes a deflection winding coupled to a retrace capacitance to form a retrace resonant circuit. A power transistor switch is coupled to the retrace resonant circuit for generating alternating current in the retrace resonant circuit. The power transistor switch energizes a primary winding of a flyback transformer that supplies a first voltage across a secondary winding of the flyback transformer. The first voltage is coupled to an inductance for forming an upramping current in the inductance. The upramping current in the inductance is coupled to the base electrode of the power transistor switch, causing the power transistor switch to be conductive during the second half of trace. A second switch, that is responsive to a deflection rate input signal, couples to the base electrode of the power transistor switch a negative supply voltage that turns off the power transistor to initiate the retrace interval.

Power switch control circuit for television apparatus

A high voltage generator develops an ultor voltage to accelerate an electron beam of a picture tube. The high voltage generator draws a resupply current in accordance with beam current loading by the picture tube. The deflection circuitry generates line and field deflection currents in respective line and field deflection windings to enable the electron beam to scan a raster. A diode modulator, including a differential amplifier input stage and an emitter-follower output stage, modulates the amplitude of the line deflection current to provide side pincushion correction. The voltage at a high voltage resupply current terminal of the high voltage generator is coupled in a nonlinear manner to the differential amplifier for nonlinearly modulating the amplitude of the line deflection current in accordance with beam current loading.

Diode modulator with raster width regulation

A television apparatus, for generating a deflection rate parabolic auxiliary deflection current that corrects convergence distortions, includes a deflection generator output stage coupled to a deflection winding. The deflection generator output stage generates a trace scanning current during a trace interval. The primary winding of a transformer is coupled in a current path of the trace current. A parabolic voltage developing capacitance is coupled across a first secondary winding of the transformer. The trace scanning current in the primary winding of the transformer causes a deflection rate parabolic voltage to develop across a second secondary winding of the transformer. The parabolic voltage across a second secondary winding of the transformer is used for generating the convergence distortion correction current.

Deflection rate parabolic waveform generating circuit

An S-correction circuit for a video display apparatus provides switchable amounts of correction in a given line deflection interval in order to satisfy the requirements of cathode ray tubes having large deflection angles or complex curvature faceplates. A second S-shaping capacitor is coupled in parallel with the main S-shaping capacitor by action of a switching transistor. The time at which the transistor is switched may be controlled, for example, by modulating the switching point at a vertical rate, in order to increase the flexibility of the correction circuit.

Switched capacitor S-correction circuit

A scan synchronized push-pull power supply for a television receiver has a source of direct voltage coupled to the primary winding of a power transformer. A first controllable switch of the power supply includes a main current path and a control terminal for controlling conduction in the main path. A second switch of the power supply includes a main current path with first and second terminals thereof. The main paths of the two switches are coupled to the primary winding in a push-pull arrangement. A deflection rate signal that is synchronized with scanning current generation is applied to the control terminal of the first switch to alternately switch conduction of its main current path between conductive and nonconductive states during each deflection cycle in synchronism with the scanning current generation. The switching of the main current path of the first switch to either the conductive or nonconductive state produces a change of voltage between two main path terminals of the second switch so as to switch the conduction state of the second switch to the one that is opposite that of the first switch. The switching action of the two switches results in the development of alternating polarity voltages across the primary and secondary windings of the power transformer.

Single controllable switch, push-pull inverter for a television receiver

An inverter coupled to a source of DC input voltage is operated at the horizontal deflection frequency for developing a horizontal rate square-wave supply voltage. A power transformer having a first winding excited by the square-wave supply voltage develops a horizontal rate alternating polarity output voltage across a linearity correction winding. A phase control circuit phases the alternating polarity output voltage relative to the phasing of the horizontal scanning current so as to apply a greater magnitude voltage across the horizontal deflection winding during the last half of the trace interval of each deflection cycle than during the first half of the trace interval. In this manner, linearity correction of the horizontal scanning current is obtained. The linearity correction winding is electrically disconnected from the circuit during the horizontal retrace interval in order to control the amount of power introduced into the deflection circuit via the linearity correction winding.

Deflection circuit with linearity correction

In a horizontal deflection circuit, a horizontal oscillator, energized by a supply voltage, develops a horizontal frequency switching signal. A deflection outputs stage is responsive to the switching signal and generates scanning current in a horizontal deflection winding. After commencement of oscillator operation, the voltage developed across a secondary winding of a flyback transformer is rectified and filtered and applied to the horizontal oscillator as the oscillator energizing supply voltage. A start-up supply for developing the oscillator supply voltage during an initial interval includes a source of voltage that is available for use prior to the commencement of oscillator operation, a capacitor, a charging circuit for charging the capacitor from the available voltage source, and a controllable switch coupled to the capacitor and to the oscillator. After the charging circuit has charged the capacitor to a predetermined threshold voltage level, the controllable switch is made conductive to apply the capacitor voltage to the oscillator to commence oscillator operation. The switch is arranged with the capacitor as a relaxation oscillator to begin discharging the capacitor by the load current drawn by the horizontal oscillator. Should the capacitor discharge to a lower threshold level before the flyback-derived supply voltage is developed, the relaxation oscillator changes states to disconnect the horizontal oscillator from the capacitor to initiate a capacitor recharging cycle.

Horizontal deflection circuit with a start-up power supply

In a television receiver with a regulated power supply that is responsive to the state of a remote on/off command signal, a power oscillator is coupled to an unregulated direct voltage source for developing an alternating input voltage of a frequency determined by the frequency of operation of the oscillator. The oscillator is provided with a frequency control terminal that controls the oscillator frequency, depending upon a control signal applied to the terminal. A ferroresonant or self-regulating circuit is energized by the alternating input voltage to produce a regulated supply voltage that in turn energizes a load circuit within the television receiver. A remote control circuit responsive to the on/off command signal applies a control signal to the frequency control terminal of the oscillator such that during the on-state of the command signal the oscillator operates at a frequency that permits normal, ferroresonant operation of the self-regulating circuit and that during the off-state of the command signal, changes the oscillator frequency to a different one that is high enough to disable the ferroresonant operation of the self-regulating circuit. The power supply is thereby placed in the standby condition wherein the television display load circuit is substantially deenergized.

Remote responsive television receiver ferroresonant power supply

A primary winding of a power transformer is coupled to a source of DC voltage. First and second controllable switches are coupled to the primary winding in a push-pull arrangement. A control circuit responsive to a deflection rate input signal that is synchronized with deflection circuit scanning applies a turn-off switching signal alternately to the two controllable switches during each deflection cycle. In response to the turnoff of each one of the two controllable switches, a turn-on switching signal is applied to the other switch to develop a deflection rate alternating polarity output voltage across an output winding of the power transformer. The output voltage is rectified and applied to a deflection generator to thereby energize the generator into developing scanning current in a deflection winding.

Television receiver, push-pull inverter, ferroresonant transformer power

In an inverter power supply, the main current paths of first and second transistors are coupled in a push-pull arrangement to a source of direct voltage and to the primary winding of a power transformer. The on-off switching of the conduction in the main current paths develops an alternating polarity voltage across the primary winding to develop a supply voltage across a secondary winding of the power transformer. A control circuit for the two transistors produces the on-off switching at a nominal fifty percent duty cycle. A signal representative of the current in the main paths of the two transistors is developed. In response to this signal, the duty cycle of the on-off switching is adjusted so as to oppose changes in the amplitude of the current in the main current paths and so as to oppose changes in the duty-cycle switching away from the nominal fifty percent.

Duty-cycle controlled inverter power supply for a television receiver

A retrace pulse voltage is applied to a first flyback transformer winding of a horizontal deflection circuit to develop retrace pulse voltages across other flyback transformer windings. Second and third windings of the flyback transformer are coupled in a series arrangement with a controllable switch across a source of input voltage. A regulator control circuit turns on the SCR at a controllable instant within the trace interval of each deflection cycle to generate input current in the series arrangement. When the retrace pulse voltage is applied to the flyback transformer first winding, the input current begins to decrease in magnitude, commutating off the SCR within the retrace interval. The leakage inductance associated with the series arrangement of flyback transformer second and third windings and the total reflected retrace pulse voltage developed by the two windings determine the instant within retrace that the SCR is commutated off. The third winding is loosely coupled with the first winding, whereas the second winding is tightly coupled with the first winding. By varying the second to third winding turns ratio, the amount of leakage inductance in the series arrangement may be varied without significantly altering the magnitude of the total reflected retrace pulse voltage.

Commutated SCR regulator for a horizontal deflection circuit

A deflection generator periodically applies a trace voltage to a deflection winding to produce scanning current and periodically generates a retrace pulse voltage across the deflection winding. A supply voltage source develops the trace voltage and also provides energy to circuits, such as a high voltage circuit, coupled to windings of a flyback transformer. The high voltage circuit develops an ultor accelerating potential from the retrace pulse voltage developed across the high voltage winding of the flyback transformer. A controllable switch such as an SCR is coupled to the source and to a secondary winding of the flyback transformer. The trace voltage and energy transfer is regulated by controlling the conduction time of the SCR. The high voltage and other load circuits draw load current from the source through the flyback transformer secondary winding during retrace, resulting in high voltage retrace pulse duration and amplitude variation with variations in load current. To maintain a constant raster width, the conduction time of the SCR is varied such that the trace voltage magnitude varies in the same sense as the retrace pulse voltage amplitude variations.

Power supply and deflection circuit with raster size compensation

In a remote controlled television receiver, the regulator circuit of the main television receiver power supply is made responsive to a remote on/off command signal in order to turn the receiver on and off. A deflection flyback transformer provides operating voltages to the ultor supply and other auxiliary supplies which power such load circuits as audio and vertical deflection. A horizontal output transistor is coupled to a B+ operating voltage terminal of the main power supply through a flyback transformer primary winding. After initiation of the on-state of the command signal, the regulator ciruit rapidly develops a B+ operating voltage. The initially uncharged filter capacitors of the auxiliary supplies act as a low impedance shunt across the flyback transformer primary winding during the start-up interval. To limit the horizontal output transistor collector current and power dissipated during start-up, the horizontal driver stage holds the forward base current supplied to the horizontal output transistor each deflection cycle during start-up below the steady-state value.

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Indianapolis, IN, United States of America

David W Luz