Importance

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Abstract

A circuit for providing AC power to an electroluminescent lamp powered by a battery comprises a high frequency oscillator through a control to drive a fly back voltage regulator comprising an inductor powered by a relatively low battery voltage and coupled to ground through a switching transistor. A capacitor coupled to the inductor through a diode is charged by the repetitive charge and discharge of the inductor when the transistor is switched ON and OFF at high frequency by the high frequency oscillator. The charge in the capacitor is dithered about a high DC voltage, such as 100 VDC, by sensing the charged voltage for periodically turning the transistor ON and OFF accordingly. A bridge circuit receives two pairs of like lower frequency square wave pulse signals of opposite polarity from a low frequency oscillator. Each signal is applied to a different one of two series connected legs of two opposite like branches, each branch coupled between the high DC voltage and ground, each leg containing two switching FET transistors and a current source. An electroluminescent lamp is connected between the legs in each branch. One of the legs in each branch is alternately turned ON and the other leg turned OFF by the square wave signals to provide the equivalent of an AC signal to the electroluminescent lamp in opposing directions, thus doubling the value of the peak stepped up DC voltage.

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First Claim