Appeal No. 98-0584
Application 08/238,948
having a table 6 defining a working surface, a cutting tool 12
and a guard 8 wherein the safety device comprises a contact-
type detector in the form of a tang 108 on a stationary micro
switch 98 which detects the presence or absence of dog 24, an
interlock system 80 which inherently includes a starting
circuit and a bypass circuit 74, 78 having a bypass switch 74
(see Figs. 10 and 11). Although the detector of Hewitt is of
the contact type, Lieber discloses a safety guard 12 and
interlock system (Fig. 1) for a power tool 11 wherein, with
respect to the detector 10, it is stated that this detector
can be
a limit switch, contact switch, magnetic
proximity switch, or any other arrangement
of switches and sensors . . . . [Column 4,
lines 22-24]
Accordingly, Lieber teaches that in the art of providing a
safety guards and interlocks for power tools, contact switches
and magnetic proximity switches are art-recognized
alternatives and the artisan would have been well aware of the
advantages and disadvantages of each. See, e.g., In re
Heinrich, 268 F.2d 753, 756, 122 USPQ 388, 390 (CCPA 1959).
In our view, the above-noted statement by Lieber would have
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