Abstract: A segmented squeegee blade is provided for optimizing the flow of a depositable material such as viscous liquid or flowable medium such as solder paste, adhesive, or the like through a stepped stencil onto a substrate. The blade has a plurality of segments adapted for substantially independent deflection with respect to each other. The blade segments deflect and conform to a stepped surface or stencil to provide for more consistent deposition of flowable material. The squeegee blade also is adapted for use with stencils having more than two step levels. The segmented squeegee blade enables component density to be increased as compared to conventional methods.

Abstract: Galvanic corrosion of the fuel sender immersed in the corrosive fuel mixture is minimized by supplying the sender with current that periodically switches polarity. The switching rate is selected to prevent or greatly minimize irreversible oxidation buildup. The vehicle body computer responds to current flow through the sender without regard to the alternating polarity drive signal. The switched polarity sender module can thus be employed without necessitating modification of the sender or body computer components.

Abstract: The motor drive circuit has an instrumentation amplifier with a programmable gain set by selectively blowing fuses during initial circuit calibration. The quasi-sawtooth waveform of a relaxation oscillator is compared with the amplified and conditioned signal produced by a pressure responsive Wheatstone bridge circuit. The result of this comparison is a drive signal which controls the pump motor speed. Radio frequency interference is minimized by storing the motor drive current in a capacitor located near the motor. Further interference is minimized by a reactive matching circuit which combines with the motor impedance to result in a purely resistive load.

Abstract: Corrosion of the fuel tank float device by electrolysis is minimized by driving the fuel level sender with short duty cycle pulses instead of a continuous current. While the fuel level sender is energized by a pulse, the analog sample and hold circuit obtains a reading from which fuel level can be determined. A synchronizing circuit controls the sequence in which the fuel level sender is energized and the reading taken, to insure that readings are taken during steady state conditions. An impedance matching circuit compensates for nonlinearities of the fuel level gauge. The impedance matching circuit includes a pair of precision resistors and a voltage multiplier circuit. The impedance matching circuit allows the moving coil fuel level gauge to be energized in a fashion which simulates a continuous current flowing between fuel level sender and gauge.

Abstract: The circuit senses abrupt change in motion of an electromotively-driven part such as the onset of valve seating in a solenoid-operated valve. A constant current source supplies power to the solenoid coil and a pulse detector circuit monitors the voltage across the coil and determines the time rate of change of that voltage. A change in the algebraic sign of the time rate of change in voltage indicates that valve seating has occurred.

Abstract: The power door lock interlock circuit senses the presence of an ignition key in the ignition and also senses when a door is open. When these conditions are met, the power door lock is placed in an interlock condition whereby pressing the power door lock button causes the horn to sound instead of locking the doors. The circuit is thus useful in preventing the driver from accidentally leaving the ignition key in the ignition and accidentally locking all doors. All doors may be unlocked in the usual fashion and all doors may be locked in the usual fashion provided the interlock condition has not been met.

Abstract: The airflow sensor uses a flow sensing bridge having a thermal element which senses airflow as a function of electrical energy applied to the bridge. Energy is applied to the bridge to maintain the thermal element at a constant temperature and constant resistance. A differential amplifier monitors the balanced and unbalanced state of the bridge and controls the application of energy to the bridge to maintain a balanced state. A microcomputer with analog to digital converter senses the level of energy applied to the bridge and converts this energy level to a digital signal indicative of airflow. The raw digital signal is corrected using calibration lookup tables and thermal compensation correction tables in the microcomputer memory circuits. The microcomputer outputs a variable frequency signal indicative of the measured mass airflow. In the alternative to the differential amplifier, the bridge may be balanced using the microcomputer in a sample and hold voltage to current converter configuration.

Abstract: The power door lock interlock circuit senses the presence of an ignition key in the ignition and also senses when a door is open. When these conditions are met, the power door lock is placed in an interlock condition whereby pressing the power door lock button causes the horn to sound instead of locking the doors. The circuit is thus useful in preventing the driver from accidentally leaving the ignition key in the ignition and accidentally locking all doors. All doors may be unlocked in the usual fashion and all doors may be locked in the usual fashion provided the interlock condition has not been met.

Abstract: The programmable telephone screening device routes an incoming call to a selected telephone device, depending on preestablished device priorities and upon access codes dialed by the caller. The device provides call hold, call forwarding and automatic dialing and is capable of testing the telephone utility network to determine DTMF and pulse dialing compatability. The device generates ringer signals for directly energizing the ringer circuits of standard telephone devices.