Appeal No. 1999-1080
Application No. 08/681,022
piston movable in a single direction as the upper
piston was retracted and sub-atmospheric conditions
were created within the chamber. The lower,
independent piston typically was provided with teeth
or other types of gripping means to prevent backward
motion, although it was found that the teeth
presented certain problems during manufacture.
Col. 1, ll. 20-29. In order to avoid the problems associated
with the earlier single chamber pump dispensers, Moore
discloses a dual chamber pump dispenser having a reservoir
chamber [14] as well as a holding chamber [26] which contains
the pump piston [68]. A check valve [28] located along a
passageway between the reservoir chamber [14] and the holding
chamber substantially
prevents pressure from the pump piston [68] to be directed
into the larger reservoir chamber [14] and toward the
independent piston [16] at the bottom of the same. Id. at 30-
38. Further, Moore shows a disc [64] yieldable in an upward
direction, as viewed in Figure 4, as the piston [68] moves
downwardly within the holding chamber [26] to admit a product
from the chamber [26] and into a passage [70]. A compression
spring [72] engages a lower horizontal wall of the valve body
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