75 F.3d 1558 (Fed. Cir. 1996), 95-1222, PPG Industries, Inc. v. Guardian Industries Corp.

Docket Nº:95-1222.
Citation:75 F.3d 1558
Party Name:37 U.S.P.Q.2d 1618 PPG INDUSTRIES, INC., Plaintiff-Appellee, v. GUARDIAN INDUSTRIES CORPORATION, Defendant-Appellant.
Case Date:February 06, 1996
Court:United States Courts of Appeals, Court of Appeals for the Federal Circuit

Page 1558

75 F.3d 1558 (Fed. Cir. 1996)

37 U.S.P.Q.2d 1618

PPG INDUSTRIES, INC., Plaintiff-Appellee,



No. 95-1222.

United States Court of Appeals, Federal Circuit

February 6, 1996

Page 1559

[Copyrighted Material Omitted]

Page 1560

Appealed from: United States District Court Western District of Pennsylvania, Judge Lancaster.

Arland T. Stein, Reed Smith Shaw & McClay, of Pittsburgh, Pennsylvania, argued for plaintiff-appellee. With him on the brief was Stanley D. Ference III. Of counsel was Cynthia E. Kernick. Also on the brief was Mark Levin, PPG Industries, Inc., of Pittsburgh, Pennsylvania.

Daniel W. Vittum, Jr., P.C., Kirkland & Ellis, of Chicago, Illinois, argued for defendant-appellant. With him on the brief was Jeffrey D. Mills.

Before MICHEL, SCHALL, and BRYSON, Circuit Judges.

BRYSON, Circuit Judge.

This case concerns a dispute between two major manufacturers of automotive glass; the dispute revolves around glass compositions known as "solar control glass," which have the highly desirable characteristics of filtering out most of the sun's ultraviolet and infrared radiation while transmitting most of the light in the visible part of the spectrum. Appellee PPG Industries, Inc., which holds a patent on a composition of solar control glass, sued appellant Guardian Industries Corporation for patent infringement and obtained a preliminary injunction from the United States District Court for the Western District of Pennsylvania. The injunction prohibits Guardian from making, using, or selling its own composition of solar control glass. We conclude that the district court did not abuse its discretion in granting preliminary injunctive relief to PPG, and we therefore affirm the order of the district court.


On August 31, 1993, the Patent and Trademark Office issued U.S. Patent No. 5,240,886 (the '886 patent), which was assigned to PPG. Shortly after obtaining the patent, PPG advised Guardian that it believed Guardian's solar control glass, known as "Solar Management Glass" (SMG), infringed PPG's rights under the patent. Litigation followed, and after a five-day hearing the district court granted PPG's motion for a preliminary injunction.

The district court found that PPG had established a likelihood of success on the merits by making a strong showing that SMG infringed PPG's rights under the patent and that the patent was not invalid. In light of PPG's showing on the merits, the court held that PPG was entitled to a presumption that it would suffer irreparable harm from Guardian's continued infringement. The court also found that the balance of hardships and the public interest weighed in favor of granting PPG's request for preliminary injunctive relief. Guardian brought this appeal, contesting the district court's ruling on each of those points.



The issue to which the parties devote the most attention is whether Guardian infringed claim 1 of the '886 patent and dependent claims 3 and 4. Claim 1 of the '886 patent defines a glass composition consisting of soda-lime-silica glass to which is added a set of ingredients that have the effect of selectively filtering out most of the sun's ultraviolet radiation. The filtering ingredients are identified in the claim as cerium (in the form of cerium oxide (CeO sub2 ) and iron (in the ferric (Fe sub2 O sub3 ) state). The claim requires that the composition have a total iron content of at least 0.85 percent by weight, and that the ratio of iron in the ferrous (FeO) state to total iron (known as the redox ratio) be no greater than 0.275. In full text, the claim reads as follows:

1. A green tinted, ultraviolet absorbing glass having a base glass composition consisting essentially of:

SiO sub2 68"75 weight % Na sub2 O 10 20 CaO 5"15 MgO 0"5 Al sub2 O sub3 0"5 K sub2 O 0"5 Page 1561

and a colorant portion consisting essentially of:

CeO sub2 Less than 0.5 weight % Total Iron Greater than 0.85 weight % (as Fe sub2 O sub 3 ) FeO/total iron Less than 0.275. exhibiting ultraviolet transmittance no greater than 31 percent (300 to 390 nanometers) and luminous transmittance (illuminant A) of at least 70 percent, both at a reference thickness of 3.9 millimeters.

Dependent claim 3 adds the limitation that the dominant wavelength of the light transmitted by the glass must be between 495 and 535 nanometers (the green color range of the spectrum), and dependent claim 4 adds the requirement that the glass must exhibit a total solar energy transmittance (including ultraviolet, visible, and infrared radiation) of less than 45 percent at a reference thickness of 3.9 millimeters.

The ultraviolet and visible light transmission requirements set forth in the claims are those established by the automotive industry as the minimum standards for acceptable solar control glass. Prior to the '886 invention (and Guardian's SMG glass), solar control glass was often made with a significant amount of cerium, a rare earth element, in the form of cerium oxide. The principal benefit of the invention claimed in the '886 patent, as explained in the specification, is that it permits a manufacturer of solar control glass to meet industry standards while adding either no cerium or relatively little cerium to the glass. Minimizing the amount of cerium used in the glass is valuable because cerium is expensive and because it has the undesirable effect, after long-term exposure to ultraviolet radiation, of darkening the glass in which it is present.

The specification of the '886 patent contains a set of examples of compositions falling within the scope of claim 1 of the patent. The examples include several compositions containing relatively small amounts of cerium (between 0.27 and 0.31 percent cerium by weight) and one composition containing essentially no cerium. Each of the examples satisfies the transmittance requirements of the claim for visible light and ultraviolet radiation. The example that contains no cerium, however, shows a particularly low redox ratio. A low redox ratio, together with a relatively large amount of iron, has the effect of compensating for the absence of cerium in filtering out ultraviolet radiation. With respect to the no-cerium example, the specification further states that

the very low ferrous to total iron ratio required when no cerium is used may be difficult to attain in some melting furnaces. Therefore, it is preferred that a small amount of cerium be used to yield the desired reduction in ultraviolet transmittance without requiring an unduly low ferrous to total iron ratio.

While the '886 patent application was pending before the PTO, PPG obtained a sample of Guardian's SMG glass and tested it. When PPG's tests showed that the SMG sample did not meet the automobile manufacturers' standards for ultraviolet transmittance, PPG advised Guardian of those results. Guardian responded that under its tests SMG met the 31 percent ultraviolet transmittance requirement for the 300 to 390 nanometer range. When PPG re-examined its testing procedures, it discovered that the software it was using in its testing equipment was flawed and that as a result the testing equipment had made an error in calculating not only the ultraviolet transmittance of the SMG sample, but also the ultraviolet transmittance of each of the examples set forth in the '886 patent specification. Because of the software error, the ultraviolet transmittance reported in each...

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