Abstract: An test cell is adapted for both making and testing samples. The cell includes a bottom plate and a top plate having concentric apertures defining a central test cavity. A post attached to the bottom plate closes off the bottom of the test cavity. A slide closes off the top of the test cavity. The top of the post is spaced slightly from the underside of the slide to define a test cavity of substantially uniform thickness. The test cavity is filled with phosphor suspended in uncured resin, closed, and the resin is cured. Once cured, the sample is stable, although delicate, and can be re-measured several times with reproducible results. The measurement takes place in the cell, using a thin film of oil for wetting surfaces.

Abstract: An inverter is coupled to an EL lamp by a high pass filter including a series capacitor and a shunt resistor. The resistor is coupled in parallel with the EL lamp. The high pass filter has a time constant greater than 0.005 seconds and the capacitor has a capacitance at least ten times the capacitance of the EL lamp.

Abstract: An test cell is adapted for both making and testing samples. The cell includes a bottom plate and a top plate having concentric apertures defining a central test cavity. A post attached to the bottom plate closes off the bottom of the test cavity. A slide closes off the top of the test cavity. The top of the post is spaced slightly from the underside of the slide to define a test cavity of substantially uniform thickness. The test cavity is filled with phosphor suspended in uncured resin, closed, and the resin is cured. Once cured, the sample is stable, although delicate, and can be re-measured several times with reproducible results. The measurement takes place in the cell, using a thin film of oil for wetting surfaces.

Abstract: A display is back lit by reflection of light from at least one point source of light, such as an LED. The reflecting surface can be far, near, or a coating on a package containing the point source of light. The point source of light faces rearwardly, i.e. emitting light away from a viewer, obscuring the source without creating an easily perceptible shadow.

Abstract: An inverter is coupled to an EL lamp by a high pass filter including a series capacitor and a shunt resistor. The resistor is coupled in parallel with the EL lamp. The high pass filter has a time constant greater than 0.005 seconds and the capacitor has a capacitance at least ten times the capacitance of the EL lamp.

Abstract: Brightness is improved, without decreasing lamp life, by driving an EL lamp at higher voltage and less current, by increasing phosphor loading, by low loss dielectric, and by depositing the phosphor layer in two passes.

Abstract: Brightness is improved, without decreasing lamp life, by driving an EL lamp at higher voltage and less current, by increasing phosphor loading, by low loss dielectric, and by depositing the phosphor layer in two passes.

Abstract: An electroluminescent lamp includes two electrodes and at least three connectors, a first connector coupled to a first electrode and a second connector and a third connector coupled to the second electrode. A first electric current flows through the lamp between the first connector and the second connector, causing the lamp to emit light. A second electric current flows through the second electrode between the second connector and the third connector, whereby the second electrode increases in temperature in response to the second electric current. When backlighting a liquid crystal display, the second electrode provides heat to warm the display for proper operation. Either electrode can be used as a heater.

Abstract: A light guide directs some light from an EL lamp into a display and absorbs or redirects the remaining light in a direction different from the preferred viewing angle for the display, thereby preserving the contrast of the display. The display includes a substantially transparent light guide having a first major surface and a second, opposed major surface and at least two opposed edges. An EL lamp is optically coupled to the light guide along a first of the opposed edges and the light guide includes grooves in one of the major surfaces for re-directing light from the EL lamp out of the one of the major surfaces.

Abstract: An EL lamp is powered by bursts of high frequency signal repeated at low frequency, i.e. having a low duty cycle envelope, in order to shift the color of light emitted by the phosphor in the lamp without degrading the life of the lamp. The bursts include one or more consecutive cycles of a high frequency signal or several closely spaced cycles of a high frequency signal.