Dimming circuit for dual display aircraft instruments
US5049869A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 19, 1989 |
| Grant date | Sep 17, 1991 |
| Priority date | — |
| Expiry date | Jun 19, 2009 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB60Q3/18
- WIPO fieldTransport
- WIPO sectorMechanical engineering
Abstract
A dimming circuit (10) for use with an illuminated dual display (12) of an aircraft instrument is provided. A voltage divider (14) divides a variable supply voltage, V.sub.S, produces an input voltage, V.sub.IN, and applies V.sub.IN to one input of a switch (16). A threshold voltage circuit (15) receives the V.sub.S voltage and produces a reference voltage, V.sub.REF, and a lower magnitude supply voltage, V'.sub.S. A reference comparator (OA3) compares the V.sub.REF and V'.sub.S voltages and produces a threshold voltage, V.sub.T. The V.sub.T voltage is applied to a second input of the switch (16). A first comparator (OA1) in the switch (16) produces a low output voltage when the V.sub.T voltage exceeds the V.sub.IN voltage and causes a first lamp (L1) to brightly illuminate a first indicia (24). A second comparator (OA2) in the switch (16) produces a low output voltage when the V.sub.T voltage is less than the V.sub.IN voltage, which causes a second lamp (L2) to dimly illuminate a second indicia (26). The illuminated first indicia (24) provides daytime illumination of the dual display (12) and the illuminated second indicia (26) provides nighttime illumination. A night vision goggl…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.