SUBSTITUTING EQUIVALENTS KNOWN FOR THE SAME PURPOSE - Patent law

As we just learned, combining compounds or materials known in the art to be useful singly for the same purpose can be prima facie obvious. It is also instructive to consider the situation that occurs where one equivalent material or compound is substituted for another in a composition or process. In this context, it is important to not focus solely on the actual equivalence of the material being substituted but also to focus on whether one of ordinary skill in the art would appreciate this equivalency. These points are addressed in the case of Smith v. Hayashi, arising from an interference matter between the listed parties.125 In the course of the interference proceeding, a “phantom count” was constructed from the subject matter corresponding to claim 1of the Hayashi application and claim 25 of the Smith application. The phantom count is as follows:
Count: An electro photographic plate for producing an electrostatic latent image on the top layer thereof which comprises from the bottom up:

  1. a conductive substrate;

  2. a layer of vitreous selenium, a vitreous selenium/tellurium alloy, a vitreous selenium / arsenic alloy or phthalocyanine having a thickness of from 0.05 to 20 microns;

  3. a top layer comprising a member selected from the group consisting of poly-N-vinyl-carbazole, poly-acenaphthylene, poly-9 (4-pentenyl) carbazole, poly-9-(5-hexyl)- carbazole. . . (numerous other chemicals listed) . . . and naphthalene, said to player being substantially visible ray trans missive and substantially non-light sensitive in the visible range in the absence of a sensitizer; the sensitizer for said top layer consisting essentially of vitreous selenium, selenium/ tellurium, selenium/arsenic orphthalocya nine layer b.

During the course of the interference, Hayashi moved to limit the scope of the count. In particular, the inclusion of phthalocyanine (part b of the count) was objected to as being a distinct, separately patentable embodiment of the invention. Hayashi wished to remove phthalocyanine from the count since it originated from only his application. By doing so, Hayashi would not have to subject that embodiment to the outcome of the interference but rather could own an invention that separately claimedphthalocyanine. In other world’s, Hayashi wanted a patent to essentially the same claim as was defined in the count, but where only phthalocyanine was claimed in the layer described by part b of the count. By arguing that phthalocyanine did not belong with the other materials listed in section b of the count, Hayashi was effectively arguing that a claim containing only phthalocyanine in part b would be patentably distinct(novel and non obvious) over the rest of the claim where vitreous selenium, a vitreous selenium/tellurium alloy, and a vitreous selenium/arsenic alloy would then make up the remaining choices for part b.
In support of the separate patentability of a claim directed to having a part b containing phthalocyanine only, Hayashi argued that the material was “not equivalent” to the other selenium-containing materials listed in the Markush (vitreous selenium,a vitreous selenium/tellurium alloy, or a vitreous selenium/arsenic alloy). Hayashi argued that phthalocyanine, a polycyclic hydrocarbon, had a multitude of properties that are different from the element selenium. The Board acknowledged as much, but they pointed out that the patentable distinction between the two materials had to be analyzed within the environment as defined by the patent claim. In other words, one has to focus on the actual function of the material when being used in the material or device that is being claimed. The Board emphasized through numerous examples,including those taught in the actual patent application specifications themselves, that the materials shared the same use in prior art photo semiconductors as comprising their “b” layers. Thus while selenium alloys and phthalocyanine are not viewed as equivalents for every possible purpose, they are equivalents for the purposes of the claimed invention. However, the Board noted that more was needed to deny separate patentability to a phthalocyanine part b layer in view of a selenium-containing part b layer, stating “the mere fact that they may be “equivalent” for this particular purpose does not establish in and of itself that one is obvious in view of the other.” For example, if a material was shown to be equivalent after the invention was made (e.g.,in a later judicial proceeding), this does not mean that the equivalence was obvious at the time that the invention was made. The question always reduces down to what one of ordinary skill in the art would perceive at the time of the invention, not what might be demonstrated later. However, in finally rejecting Hayashi’s attempt to separately claim phthalocyanine in the part b layer, the Board noted that the evidence of equivalence was noted in the prior art, and accordingly, the replacement of one equivalent with another is strong evidence of obviousness.


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