Abstract: A traffic signal display apparatus includes a display surface having a plurality of bicolor bipolar LEDs thereon in an array. When current is fed into the LEDs in a first direction, the bicolor bipolar LEDs display a first color, which may be green. When current is fed in the opposite direction, the bicolor bipolar LEDs display a second color, which may be red. When current is fed into the array alternately in both directions, the bicolor bipolar LEDs display a third color, which may be yellow. The display apparatus may be subdivided into multiple independent zones, allowing arrows to be displayed. The single display apparatus can therefore be used to replace the three to five stacked conventional traffic light display units.

Abstract: A traffic signal display apparatus includes a display surface having a plurality of bicolor bipolar LEDs thereon in an array. When current is fed into the array in a first direction, the bicolor bipolar LEDs display a first color, which may be green. When current is fed into the array in a second direction, the bicolor bipolar LEDs display a second color, which may be yellow or amber. When current is fed into the array alternately in the first and second directions, the bicolor bipolar LEDs display a third color, which may be red. The display apparatus may be subdivided into multiple independent zones, allowing arrows to be displayed. The single display apparatus can therefore be used to replace the three to five stacked conventional traffic light display units.

Abstract: In a displacement measurement system using waves in the sonic to ultrasonic range, a constant wavelength of the sonic or ultrasonic wave is established by driving the wave transmitter by a variable frequency oscillator whose frequency is varied as a function of a control voltage. The control voltage is varied as a function of the phase differential between the wave transmitted by the transmitter and the wave received by reference receiver to maintain both waves in phase.

Abstract: A bridge type pneumatic circuit, for pneumatic gauging, having an inlet and two branch passageways through which flow of compressed air from an inlet to an outlet of each branch passageway is controlled by an adjustable orifice. One of the outlets is connected to the nozzle, or nozzles, of an air gauge head, such that the pressure of the air flowing past the corresponding adjustable orifice varies as a function of the distance separating the nozzle from the surface, while the other branch passageway is vented to atmosphere through a calibrated orifice to establish a zero reference. The differential pressure between the passageways downstream of the adjustable control orifices is monitored by a differential pressure transducer to provide a control signal to a measurement display instrument. In the alternative, the outlet of the second branch passageway is also connected to the nozzle, or nozzles of an air gauge head, to effectuate differential measurements.