Abstract: A liquid crystal display (LCD) system having LED backlight luminance sensing is disclosed. An array of LEDs in a backlighting position includes a plurality of LED strings. At least one LED from at least one string is identified as a sampling LED. The light emitted from the sampling LED is detected via an optical path using a light sensor. The reading from the sensor is contrast with a command, which results in a power compensation to the array accordingly. In one embodiment, the system includes a sampling enclosure encasing the sampling LED and light sensor. The sampling LED's direction of emission is altered from the string and reflected from the inside of the enclosure. In another embodiment, the system includes a direct sensing optical path between the light sensor and the sampling LED.

Abstract: A liquid crystal display (LCD) system having LED backlight luminance sensing is disclosed. An array of LEDs in a backlighting position includes a plurality of LED strings. At least one LED from at least one string is identified as a sampling LED. The light emitted from the sampling LED is detected via an optical path using a light sensor. The reading from the sensor is contrast with a command, which results in a power compensation to the array accordingly. In one embodiment, the system includes a sampling enclosure encasing the sampling LED and light sensor. The sampling LED's direction of emission is altered from the string and reflected from the inside of the enclosure. In another embodiment, the system includes a direct sensing optical path between the light sensor and the sampling LED.

Abstract: An apparatus for use in dimming florescent lamps by alternating cathodes operated with pulsating unidirectional arc currents for a duration that is long relative to the filament thermal time constant, but short in relation to the mercury migration time constant of the florescent lamp. The invention provides apparatus using full bridge switching and full bridge clamping topology in a trigger driver as well as a power driver to prevent low voltage power supply "ride up". The invention further provides means for sensing cathode heater current to detect a failed cathode and to control the phase switching to a good cathode if a cathode failure occurs. The invention further provides apparatus for a balanced-to-group ground lamp drive voltage for improved ignition of the lamp plasma and better lamp luminance uniformity when the lamp is operated dimly. A logarithmic amplifier is provided in a closed loop operation for analog compression and also to provide a logarithmic dimming response.

Abstract: A fluorescent lamp dimmer, for use with one or more fluorescent lamps where large ratios of luminous differences are required, which includes apparatus for powering the arc current for the fluorescent lamps from a source of pulsating voltage of variable pulse width and variable frequency both of which can be changed by relatively small amounts and still produce very large changes (15,000:1) in luminescence.

Abstract: An electromagnetic deflection display system is operative for bi-directional raster and stroke deflection and provides minimum power dissipation in raster mode during a segmented or patch raster display. Energy stored in the deflection yoke during one direction of the raster scan is returned to an energizing power supply during the subsequent return scan in a manner that conserves power while avoiding an over-voltage condition of the associated power supply. A transformer is coupled to receive a portion of the energy stored in the yoke and return it to a designated raster mode power supply. The raster mode return voltage may be determined independently of stroke mode power requirements so as to optimize raster power savings and ampifier raster performance independent of the optimum stroke voltages.

Abstract: Apparatus for reducing the effects of beat frequencies in systems having multiple oscillators wherein a wide band frequency modulator operates to alter the frequency supplied by one of the oscillators at a rate high enough that any beat frequencies occur at rates undetectable to the human eye.

Abstract: An apparatus for applying convergence corrections to correct positional and misconvergence errors in a CRT employing a self-converging deflection yoke for magnetic deflection of an inline color gun assembly. Convergence correction coil windings are coupled to the deflection windings with the inductances and resistances of the convergence windings selected to match the time constants of the associated deflection windings. The applied deflection current signals are thereby apportioned between the deflection and convergence coils to modify the beam deflection and provide a beam deflecting flux proportional to the commanded deflection signals and a beam deflection center that is independent of the pattern written on the screen. The resulting currents in the deflection coils and convergence coils are a substantial replica of the commanded deflection current signal waveforms.

Abstract: A pneumatic control valve of the flapper type for controlling the resultant pneumatic pressure within a chamber from two sources of pressure in proportion to an electrical control signal is disclosed, wherein two flappers, one associated with a nozzle connected with one of said sources and the other associated with a nozzle connected with the other thereof, are resiliently coupled to a common electrically actuated armature such that at least at extreme controlled pressure rates, the resilient coupling permits one flapper to close its nozzle while permitting the other to continue to control the pressure rate from the other nozzle whereby to permit reducing the flapper-nozzle gap and to enlarge the nozzle area resulting in a very high valve gain and at the same time reducing quiescent pneumatic mass flow and increasing the transient pneumatic mass flow capability through said valve.

Abstract: A dual closed loop, precision pneumatic pressure selection, control and display system for use in testing pneumatic apparatus provides precision digital high response analog control of a precision pneumatic valve for establishing, maintaining, and displaying selected reference pressures and rates of change thereof as a ratio between a regulated pressure and a vacuum, the resultant pressure being sensed by a precision pressure sensor of the vibrating diaphragm type. The first closed loop is a digital loop, the desired reference pressure or pressure rate being commanded in any desired pneumatic unit of measure as a binary coded decimal signal and converted to a common unit of measure. The output of the pressure sensor responsive to valve operation is converted to a binary coded decimal signal in said common units, these two signals being digitally compared and the difference between them being converted to an analog signal for adjusting the valve, thereby maintaining the selected pressure.