Baldwin-Lima-Hamilton Corp. v. Tatnall Measuring Systems Co.

169 F. Supp. 1, 120 U.S.P.Q. (BNA) 34, 1958 U.S. Dist. LEXIS 3009, 1958 Trade Cas. (CCH) 69,358
District Court, E.D. Pennsylvania·Decided December 1, 1958·No. Civ. A. 23505·Published·Cited by 48 cases

Opinion

*6 STEEL, District Judge.

Simmons, a patentee, and his licensee, Baldwin-Lima-Hamilton Corporation (hereinafter “Baldwin”) have sued The Budd Company (hereinafter “Budd”) and its wholly owned subsidiary, Tatnall Measuring Systems Company (hereinafter “Tatnall”), for infringement of Claims 1, 2, 3, 4, 5, 7, 8 and 9 of Patent No. 2,292,549 (hereinafter “Simmons patent”). The patent relates to a gage for measuring strain in materials.

Baldwin has marketed “bonded wire strain gages” under the Simmons patent since 1940. Without license from plaintiffs, Tatnall has manufactured, used and sold “foil type” strain gages and Budd has used “foil type” strain gages manufactured by Tatnall. The ■“foil gages”, plaintiffs charge, infringe the Simmons patent.

In defense the defendants have pleaded (a) noninfringement; (b) invalidity because of (i) anticipation, (ii) lack of invention and obviousness, (iii) inadequacy of patent description, and (iv) inclusion of new matter in amendment to application; and. (c) unclean hands because of (i) fraud on the Patent Office, and (ii) patent misuse.

Jurisdiction exists under 28 U.S.C. § 1338(a).

Subject Matter of Simmons Patent

The load or force which is applied to a body is known as “stress”. It may be expressed in terms of pounds per square inch. When a body is subjected to stress, it is deformed to some extent. The deformation is known as “strain”. It may be expressed in terms of inches of strain per inch of length.

In any material used for engineering purposes, the stress must be kept within safe limits to prevent failure. Well-known and determinable relationships exist between stress and strain in engineering materials. Where the strain in a material is known at a given point, the stress at that point can be ascertained.

The purpose of the Simmons gage is to measure strain. The gage employs the principle discovered by Lord Kelvin more than a century ago that the electrical resistance of materials which are electrically conductive varies with the strain thereof. If the material is stretched, its resistance will increase; if it is compressed, its resistance will decrease. This property is referred to in the Simmons patent as “electrical strain sensitivity”.

Claim 5 contains three elements: (i) a test body whose strain is to be measured, (ii) a continuous metallic filament of solid electrical conducting material whose electrical resistance varies in accordance with changes in strain in the filament, and (iii) a means for adhesively bonding the filament in an untaut condition throughout its effective length to the body to be tested so that the filament forms a completely unitary part of the test body 1 . When a filament described by Simmons is bonded to a test body as Simmons has directed, any deformation of the test body will cause a corresponding deformation in the filament (for instance, a lengthening of the test body will cause a commensurate lengthening of the filament) and the electrical resistance of the filament will vary as deformation changes occur. By an appropriate electrical circuit (not subject to the Simmons patent) the variance in the *7 electrical resistance of the filament can be recorded. By comparing such resistance changes with the predetermined electrical strain sensitivity of the filament, the strain in the test body can be ascertained.

Infringement

35 U.S.C. § 271(a) defines infringement as the unauthorized making, using or selling of a “patented invention”. The critical question, therefore, is what the Simmons patented invention is, and whether the foil gages manufactured by Tatnall embody it.

The sketches below have been agreed upon by counsel as magnified versions of the Baldwin gage (wire type) and the Tatnall gage:

In the Simmons bonded wire gage the electrical current flows from one end of the wire to the other, and the entire length of the wire, wound back and forth, is the gage. In the foil gage of defendants the current flows from one lead connection tab through the first straight length of foil, then across the enlarged connecting portion of foil, then down through the next straight length of foil, then across the next enlarged connecting portion of foil, and so on, to the other lead connection tab. As in the Simmons gage, the foil gage is bonded to the specimen to be tested, thereby becoming a slave, as it were, of the test body, and deforming precisely as the test body deforms. With the occurrence of deformations in the foil measurable variations take place in the electrical resistance of the foil. The Simmons wire strain gage operates on this same principle.

Defendants contend that the invention of Simmons is limited to a “filament” in the form of a wire, that the foil of defendants’ gage is neither a wire nor a filament, and that therefore the foil gage does not embody Simmons’ invention. Plaintiffs assert that Simmons did not limit his invention to a filament which was a wire but intended filament to have a connotation sufficiently broad to comprehend the foil conducting elements of the defendants’ gage.

Claim 5 is not in words restricted to a filament in the form of a wire. But the claims of a patent need not be read in a vacuum. For purposes of determining whether an accused device is an infringement, the claims of a patent are to be interpreted not only in the light of the specification but also with reference to the file wrapper history. Mas v. Owens-Illinois Glass Co., D.C.D.N.J. 1954, 122 F.Supp. 582, 583; affirmed, 3 Cir., 1955, 222 F.2d 889; certiorari denied 350 U.S. 1016, 76 S.Ct. 661, 100 L.Ed. 875; rehearing denied, 1946, 351 U.S. 943, 76 S.Ct. 838, 100 L.Ed. 1470. Here, both the specifications and the representations which Simmons made to the Patent Office during the patent prosecution establish that the filament which Simmons claimed as an element of his invention was a filament in the form of a wire.

Thus, Simmons says in his specification, “To determine the strain * * * I employ my improved strain sensitive electrical means consisting of a filament of very fine metallic wire” 2 . At other places in the specification the word “filament” is used in conjunction with “wire”; as for example, “wire filament” 3 and “wire forming a filament” 4 .

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Baldwin-Lima-Hamilton Corp. v. Tatnall Measuring Systems Co., 169 F. Supp. 1, 120 U.S.P.Q. (BNA) 34, 1958 U.S. Dist. LEXIS 3009, 1958 Trade Cas. (CCH) 69,358 (E.D. Pa. 1958).

169 F. Supp. 1 (Baldwin-Lima-Hamilton Corp. v. Tatnall Measuring Systems Co.) — published by Counsel Stack Legal Research, free access to 12M+ legal documents.

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