Interference No. 103,036
nonconductive layers is a conductive layer 64 which
has a reduced cross sectional area 65 in a sealed
chamber or indicator zone 66. In contact with the
conductive layer is either a color indicating heat
sensitive material 70, a pyrotechnic chemical 68, or
the color indicating heat sensitive material in
combination with the pyrotechnic chemical. When this
embodiment of the battery strength indicator is
electrically connected across the terminals of the
battery, current flows through the conductive layer
64. Because the conductive layer is reduced to a
small cross section 65 in the indicator zone 66, the
resistance of which is selected such that current
flow at a minimum predetermined voltage will raise
the area 65 to a predetermined temperature, the heat
generated by the conductive layer raises the temper-
ature of the color indicating heat sensitive material
to a predetermined temperature for color change to
indicate the voltage or strength of the battery.
17. The insulative or nonconductive layers
described in the Burroughs '544 patent are present to
shield components of the strength indicator which
transmit heat and/or electricity, and are indicated
as doing so. For example, in the indicator device
10D shown in Fig. 10, nonconductive layers 30 and 32
(attached to the side of the battery housing)
surround the "color indicating, heat sensitive
material 70 which undergoes a visible color change
when the material is heated to at least a
predetermined temperature" (column 8, lines 37-41).
In order for this embodiment to be operable when
applied to the side of a dry cell battery, the
construction of the battery strength indicator,
including the nonconductive layers, must be such to
permit sufficient heat generated by the reduced cross
section conductive area 65 to flow to the color
indicator material to cause a color change. Heat
generated by the reduced section conductive area 65
is within the sealed chamber or zone 66 adjacent to
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Last modified: November 3, 2007