Appeal No. 2000-1085
Application No. 08/980,349
The dispositive question is whether it would have been
obvious to one of ordinary skill in the art to employ tin oxide
doped with phosphorus as the conductive layer material of the
conductive pigment described in either Bruckner or Stahlecker.
On this record, we answer this question in the affirmative.
Although both Bruckner and Stahlecker teach that any
conventional conductive metal oxide or mixtures of metal oxides
can be used as the conductive layer material of their conductive
pigment, they indicate a preference for tin dioxide doped with
antimony as the conductive layer material. See Bruckner, column
2, line 65 to column 3, line 10 and Stahlecker, column 2, line 64
to column 3, line 25. However, Okuda teaches (page 2, lines 6-
11) that:
As an electroconductive powder, carbon black has
been known, but its use is highly restricted because of
its black colour, poor dispersibility in vehicles, of
containing carcinogenic substances, and like
limitations. Recently, tin oxide powder doped with
antimony, or titanium dioxide powder coated with a
layer of tin oxide doped with antimony have been
developed and used.
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