Claim Construction – Interpretation to Determine Obviousness

The present case relates to reexamination (Reexamination No. 90/008,482) of US Patent No. 5, 236, 503, referred to as ‘503 hereinafter. The concerned Applicant GLATT AIR TECHNIQUES, INC. (referred to as Glatt hereinafter) appealed against the order of the Board of Patent Appeals and Interferences, which was decided on 5’th Jan 2011.

As an introduction, a third party requested ex parte reexamination of the patent. The U.S. Patent and Trademark Office (“PTO”) granted reexamination as to claims 5-8 and 10 of the ’503 patent. During reexamination, Glatt canceled claims 6, 7, and 9-11, limiting the reexamination to un-amended claim 5 and amended claim 8. The examiner rejected claim 5, but allowed amended claim 8. Glatt appealed the examiner’s rejection of claim 5 to the Board, which affirmed the examiner’s rejection.

The invention relates to a coating apparatus known as a “Wurster Coater” used to coat particles, e.g., pharmaceutical ingredients. Wurster coaters work by spraying the desired coating material onto particles circulating within the apparatus. The existing coating apparatus suffer from particle agglomeration, which increases the amount of time it takes to coat the particles. This agglomeration occurs because the circulating particles prematurely enter the stream of coating spray before the spray pattern has fully developed. This premature entry causes the particles to become overly wet and to stick together thereby causing blockages in the apparatus.

Glatt’s solution to this problem involves shielding the coating spray nozzle to prevent the particles from entering the spray prematurely. Glatt does this by creating a cylindrical partition that surrounds the coating spray nozzle and acts as a physical shield to prevent premature entry of the circulating particles. Col 5 Lines 3-12 of the Specification of Glatt’s patent additionally notes that “other shielding arrangements may be utilized. For example, shielding of the spray nozzle may be accomplished by formation of an air wall or stream that surrounds the nozzle and prevents particles from prematurely entering into the spray pattern.”

Following is the contested claim 5 of Glatt:

5. In a fluidized bed coater having a product container opening upwardly into an expansion chamber and downwardly into a lower plenum chamber through an air distribution plate/screen having openings formed therethrough for upward air flow from said lower plenum chamber into said product container, said product container including a substantially cylindrical partition spaced above said air distribution plate/screen for defining an inner upbed area and an outer downbed area, and an upwardly discharging spray nozzle mounted substantially centrally within said cylindrical partition,

the improvement comprising

shielding means positioned adjacent said spray nozzle for shielding the initial spray pattern developed by said nozzle against the entrance of particles moving upwardly through the upbed.

As can be seen, Claim 5 of the Glatt is written as a Jepson Claim, wherein the preamble is rendered as the prior art and the invention is the improvement. i.e., a shield used in the Wurster coater. Improvement portion of claim 5 also has a means-plus-function limitation—a “shielding means.”, wherein in a means-plus-function claim, scope of the claim is limited to the embodiments listed in the specification of the patent.

As the proposed novel part of the claim was considered as “shielding means positioned adjacent said spray nozzle”, during the re-examination procedure, the examiner identified DE 3323418 (“Naunapper”) and rendered Claim 5 (Jepson Claim) as obvious keeping in mind the embodiment put across in the specification of ‘503 Patent, which stated “shielding means” to include “formation of an air wall or stream that surrounds the nozzle and prevents particles from prematurely entering into the spray pattern”. The examiner contended that Naunapper discloses “an air wall, or air jacket, surrounding said spray nozzle” thereby rendering the Applicant’s invention obvious. After an appeal to the  board, the board of appeals too affirmed with the examiner and contended that the claimed subject matter was obvious as an air wall that surrounds the nozzle as disclosed by Naunapper would render all possible physical or air wall based shielding mechanisms of Glatt obvious.

When the matter was appealed to the US Court of Appeals, the Circuit Judges held that as Glatt does not contest that the preamble to claim 5 is admitted prior art, the inquiry is limited to whether Glatt’s invention as a whole would have been obvious to a person of ordinary skill in the art in view of the prior art Wurster coaters described in the claim and the Naunapper reference. It was understood that both Glatt’s invention and Naunapper’s coating apparatus contain coating spray nozzles and that both also include an air source located below the coating spray nozzle. Further, the air is used to circulate the particles in the apparatus into the spray of coating material.

However, additionally, Glatt’s invention includes an element that reduces particle agglomeration, described and claimed as “a shielding means that prevents the circulating particles from prematurely entering the initial spray pattern”. Naunapper, on the other hand, contains no such element and the PTO argues that the air source itself can be used to generate an air wall that shields the particles from the initial spray pattern. It was further held that the PTO indicates that Naunapper combats the particle agglomeration problem by temporarily increasing the airflow from the air source. The modulated “burst” of air/gas flow generated by this technique clears blockages by blowing through the agglomeration and dispersing the particles.

It was finally held that, that the proposed technique of Naunapper does not shield circulating particles from entering the initial spray pattern and rather merely teaches to remedy the blockage caused by particle agglomeration using bursts of air. In contrast, Glatt’s invention prevents the agglomeration from occurring in the first place. This led to the decision that the Board’s finding that Naunapper teaches shielding the nozzle to prevent particles from prematurely entering into the initial spray pattern is not supported by substantial evidence because Naunapper does not teach shielding but instead discloses the prevention technique of using airflow for combating and clearing of blockages by blowing through the agglomeration. Because Naunapper does not teach shielding, the federal circuit concluded that the Board has failed to make a proper prima facie case of obviousness.

Key Take Away’s:

1.      Determination of scope of protection of a means plus function claim should take into consideration all embodiments disclosed in the specification of the patent application and specifically the preferred embodiments as illustrated/described in the specification.

2.      Disclosing a potentially similar structure but a completely different purpose (an air wall of Naunapper vs.  formation of an air wall or stream of Glatt) does not objectively render the concerned application obvious. The intended purpose too plays a crucial role in determining the teaching or suggestion of the claimed subject matter by the prior art.

About the Author: Mr. Tarun Khurana, Partner and Patent Attorney in Institute of Intellectual Property Research & Development (IIPRD) and can be reached: Tarun@iiprd.com.

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