A timed lighting display adjacent the chart drive area of a polygraph indicating when the examiner and examinee have time to ask and respond to a test examination question before the next question.
A chart recorder apparatus wherein information is indicated by using light emitting devices which are disposed to access the rear surface of a chart on which measured signals of a chart recorder are recorded on a front surface thereof. Various types of information are projected and indicated without otherwise compromising features of a chart recorder and thereby enhancing functionality of a compact chart recorder having a small display area.
A panel having an array of backlighted windows for displaying a change in a process variable from a nominal condition to a changed condition comprising a thin, sealed frame and a circuit board with an array of LEDs interconnected for each window and a binary switch coupled to the LED array that energizes the LEDs on receipt of a binary logic signal. The panel can be operated in a stand-alone unit or be backfitted to an existing data recorder, tapping into the incoming or internal logic variable signals and power supply without disturbing the underlying function of the recorder.
