Appeal No. 2001-2019
Application No. 08/996,567 Page 7
alarm are being controlled by a change in voltage on the power
lines.
We find that Berry, III is directed to an emergency alarm
system with both audible and visual signal devices (col. 1, lines
14-16). A master control panel 10 connects to a plurality of
alarm units 308 through a two conductor transmission line 304,
306 (col. 16, line 67 through col. 17, line 1). Control panel 10
supplies DC power on lines 20 (C,D) (col. 17, lines 39-42) and
supervisory and alarm functions on lines 22 (E,F)(col. 5, lines
64-68; col. 6, lines 7-11, and figure 1). An interface module 34
(figure 2) is connected control panel 10 (col. 6, lines 42-45)
and alarm units 308. As shown in figure 6, each alarm unit 308
includes an electrical lamp 310 and a loud speaker 312. The
alarm units operate in one of three alarm modes: (1) solely an
audible alarm mode from the units; (2) solely a visual alarm mode
from the units, and (3) a combination of both audible and visual
alarm modes from the units (col. 17, lines 4-8). In the absence
of an alarm condition, control panel 10 provides a negative d.c.
voltage on terminal E with respect to terminal F. With the coil
of relay K8 deenergized, contacts K8A and K8B are in the position
shown in figure 6. Line 304 is negative with respect to line 306
which causes reverse bias to be applied to diodes 318. Blocking
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Last modified: November 3, 2007