Appeal No. 95-4678
Application 08/097,572
mountable on the exit sign housing when the emergency
illumination means is not mounted within the exit sign housing
enclosure.
Duncan discloses a “lighting unit embodying a secondary
lighting system which will function to maintain illumination in
the event of a break down [sic] in the main lighting system due
either to a failure in the supply current or to failure of the
lamp itself” (page 1, lines 12 through 17). As described by
Duncan,
[r]eferring first to Fig. 1, there is shown a
sign 1 of general box-like form and having a removable
front panel 2 which has the words [e.g. EXIT] or matter
to be displayed cut out or stencilled [sic] thereon.
An angle section strip 3 is fixed within the casing as
shown to provide a supporting surface 4 for the lamps,
said strip also defining a rear compartment 5 which
houses the relay and associated mechanism. A dry
battery 6 for operating the secondary lighting system
is shown supported on the platform 4 but it will be
understood that the battery also may be accommodated in
the rear compartment, if desired, or the several
components may be arranged in any other convenient
manner within the casing.
Referring now to Fig. 2, the primary lighting
system is shown as comprising a lamp 7 connected to an
A.C. “mains” supply 8 for operation at the mains
voltage and, in association therewith, there is
provided a low voltage secondary lighting system.
. . . The secondary system in this instance comprises
two lamps 13, although the number of these lamps may of
course vary according to requirements, and to feed
these lamps a suitably reduced voltage is taken from
the mains through a step-down transformer 14 or, if
desired, by a direct drop through a resistance or a
5
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Last modified: November 3, 2007