GB1346012A - Indicator display - Google Patents

Abstract

1346012 Indicating apparatus; compasses ELECTRO MARINE CORP 6 Oct 1972 46198/72 Headings G1F and G1J An indicator display in which the same information is presented in both analogue and digital form comprises a casing 10 having two windows 12, 14 in one wall, a graduated dial 22 having peripheral scale divisions, mounted on a shaft 20 for rotation therewith, with the shaft axis to one side of the window 12 so that only a sector of the dial 22 is visible through the window 12, and a digital display 28 behind the window 14. In the marine compass display shown, the dial 22 is graduated as a compass card which moves relative to a fixed pointer 26, and the display 28 shows the heading in degrees. A heading signal is supplied to a synchro transformer 35, the output of which is amplified to drive a servo motor 36 coupled to the shaft 20 of the dial 22. The rotor of synchro 35 is driven from the shaft 20. To allow for variation correction, a differential synchro (32) Fig. 3, (not shown), controlled by a graduated knob 15 via reduction gearing (34), is provided ahead of the synchro transformer 35. The shaft 20 also drives a digital encoder 40, which may be a rotary switch or an optical encoder having a rotatable input disc carrying alternate opaque and transparent spots which control the light to photo-diodes. Following the encoder 40 is a decoder-driver circuit for the digital display 28. A knob 16 controls the brightness of the display. The display is also applicable to a liquid level gauge, a temperature gauge, a salinity gauge, a cable length measure, or other angular measurement devices.