PPG Industries, Inc. v. Guardian Industries Corp.

Decision Date06 February 1996
Docket NumberNo. 95-1222,95-1222
Citation75 F.3d 1558,37 USPQ2d 1618
Parties, 37 U.S.P.Q.2d 1618 PPG INDUSTRIES, INC., Plaintiff-Appellee, v. GUARDIAN INDUSTRIES CORPORATION, Defendant-Appellant.
CourtU.S. Court of Appeals — Federal Circuit

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.

I

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.

II
A

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
                

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 example was about three percent too high; thus, the glass tested in each example was actually filtering out about three percent more ultraviolet radiation than the testing equipment indicated. That error had led the inventors to suggest in the specification that a glass meeting the limitations of the patent and containing no cerium at all might be difficult to make commercially, as it would require a redox ratio that would be hard to achieve in some commercial furnaces. In fact, however, the transmittance limitations of the claims for a no-cerium glass are not as difficult to satisfy as the specification suggests, because after an adjustment is made for the three percent calculation error, the redox ratio for the no-cerium embodiment does not have to be as low as the specification indicates.

Based on the three percent calculation error, Guardian argues that the claims of the '886 patent do not cover SMG. If the claims are read in light of the specification, Guardian argues, they cannot be construed to apply to SMG, because the examples in the specification make clear that the inventors did not believe that a glass having the composition of SMG would satisfy the 31 percent ultraviolet transmission requirement.

The problem with Guardian's argument is that the claims simply cannot be construed as Guardian suggests. By their plain terms, the claims read on SMG: the critical limitations require that the glass contain less than 0.5 percent cerium and more than 0.85 percent iron, that the redox ratio of the iron components be less than 0.275, that the ultraviolet transmittance be no greater than 31 percent, and that the visible light transmittance be at least 70 percent. SMG satisfies all of those limitations and thus infringes claim 1 of the '886 patent. Moreover, because the dominant wavelength transmitted by SMG is within the green range (495 to 535 nanometers) and because SMG's total solar energy transmittance at the 3.9 millimeter reference thickness is less than 45 percent, it falls within the limitations of dependent claims 3 and 4 as well.

It is true that if Guardian's SMG glass is tested with the same flawed testing equipment that was used to prepare the examples in the '886 patent specification, SMG's ultraviolet transmittance would appear to be above the 31 percent maximum set forth in the claims. But the '886 patent claims are not qualified in that manner; the claims cover...

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