Abbott Laboratories Corporation

Arie Ravid

Robert G Poli

A voltage converter and a method for converting AC to DC. A MOSFET (42, 118) conveys current from a full wave rectifier to charge a capacitor (60) that supplies current to a load (64). In a first embodiment, two transistors (32, 34) are connected as a differential pair to control the voltage applied to the gate of the MOSFET, referenced to a zener voltage developed across zener diode (36) that is connected to the emitters of the two transistors. In a second embodiment, a single transistor controls the voltage applied to the gate of the MOSFET, relative to a zener voltage of a zener diode (132). The MOSFET charges the capacitor while the voltage applied to its gate from the rectified signal is greater than the voltage across the capacitor.

High efficiency voltage converter and regulator circuit

Redundant segment display characters are used to provide a fail-safe indication of critical parameters. In one preferred form of the invention, selected segments of a redundant segment character include pairs of segments that are arranged proximate to each other and extend generally parallel to each other. The pairs of redundant segments are activated simultaneously in response to multiplexed fore plane and back plane drive signals applied to conductive regions of a liquid crystal display. The remaining portions of the redundant segment character each comprise single activated regions. The portions of the display character that include redundant segments are selected to minimize errors in reading a numeric value indicated by the character in the event that one of the segments fails to operate properly. In another preferred form of the invention, all of the portions of the character are pairs of redundant segments. In yet another embodiment, the pairs of redundant segments are arranged serially, end-to-end. In the event that one of the redundant segments fails to activate or always remains activated, such failure is visually apparent to an operator by comparison to the other segment of the redundant pair.

Display having redundant segments

A power supply that converts an unregulated DC voltage source to a regulated AC power source suitable for energizing an electroluminescent panel. The DC voltage source powers a DC-to-AC inverter to generate an AC output. A feedback circuit monitors the AC output and compensates for any changes in amplitude that arise due to fluctuations in the DC input voltage. A single reference voltage is used to both selectively energize and deenergize the circuit and to control the amplitude of the AC output.

Regulated electroluminescent panel power supply

A character display in which failures are evident. Selected segments of a seven-segment LCD are activated by control signals supplied through selected fore plane and back plane traces. By coupling specific ones of the fore plane and back plane control signals to selected segments, any failure in the control signal or circuitry providing the signal to the segments of the display character becomes immediately evident to an operator when the character represented by the display is not one of a predefined set of characters.

Growing community of inventors

Palo Alto, CA, United States of America

Arie Ravid