Donaldson Co., Inc., In re, 91-1386

• Citation: 16 F.3d 1189,29 USPQ2d 1845
• Decision Date: 14 February 1994
• Docket Number: No. 91-1386,91-1386
• Parties: In re DONALDSON COMPANY, INC.
• Court: U.S. Court of Appeals — Federal Circuit

Page 1189

16 F.3d 1189

29 U.S.P.Q.2d 1845

In re DONALDSON COMPANY, INC.

No. 91-1386.

United States Court of Appeals,

Federal Circuit.

Feb. 14, 1994.

R. Carl Moy, Merchant, Gould, Smith, Edell, Welter & Schmidt, P.A., of Minneapolis, Minnesota, argued for appellant.

Fred E. McKelvey, Solicitor, Office of the Solicitor, of Arlington, Virginia, argued for appellee. With him on the brief were Richard E. Schafer, Associate Solicitor and James T. Carmichael, Assistant Solicitor. Of counsel was Albin F. Drost.

Herbert I. Cantor, Wegner, Cantor, Mueller & Player, of Washington, D.C., was on the brief for Amicus Curiae, Bar Association of the District of Columbia. With him on the William L. LaFuze, Vinson & Elkins, of Houston, Texas, was on the brief for Amicus Curiae, American Intellectual Property Law Association. With him on the brief were Nancy J. Linck, Cushman, Darby & Cushman, Washington, D.C., Harold C. Wegner, Wegner, Cantor, Mueller & Player, Washington, D.C. and H. Ross Workman, Workman, Nydegger & Jensen, of Salt Lake City, Utah, of counsel.

brief were John W. Schneller, Chair, Patent, Trademark and Copyright Section and Anthony W. Shaw, Chair, Amicus Committee.

Before NIES, Chief Judge, and RICH, NEWMAN, ARCHER, MAYER, MICHEL, PLAGER, LOURIE, CLEVENGER, RADER, and SCHALL, Circuit Judges.

RICH, Circuit Judge.

The Donaldson Company (Donaldson) appeals from the January 30, 1991 decision of the Board of Patent Appeals and Interferences (Board) of the United States Patent and Trademark Office (PTO), reaffirmed on reconsideration on April 17, 1991, sustaining the Examiner's rejection of claim 1 of reexamination application Serial No. 90/001,776 ¹ (Schuler application) under 35 U.S.C. Sec. 103. We reverse.

I. BACKGROUND

A. The Invention

The present invention relates to industrial air-filtering devices often referred to as "dust collectors." Fig. 2 of the Schuler application is reproduced below.

NOTE: OPINION CONTAINS TABLE OR OTHER DATA THAT IS NOT VIEWABLE

In operation, dust-laden air enters dirty-air chamber (22) through air inlet (20) at the top, passes through filters (32), and then exits through clean-air outlet (64) at the left. During this process, dust is collected on the outside of the filters. To periodically dislodge accumulated dust from the filters, the Schuler collector includes valve and nozzle assemblies (65), which direct jets of compressed air into the hollow interior of each filter. In doing so, the normal direction of air flow is reversed, thus dislodging a substantial portion of the dust accumulated on the outside of each filter. The dislodged dust then falls through the dirty-air chamber and accumulates at the bottom of the chamber in hopper (25), where it is removed by auger screw (68).

One problem with conventional collectors is that the dust accumulated in the hopper tends to harden or cake, thus interfering with the free movement of the accumulated dust downward to the auger screw. To overcome this problem, the Schuler collector takes advantage of the fact that every pulse of air from the nozzles causes the pressure within the dirty-air chamber to increase momentarily. At least one wall of the hopper of the Schuler collector (24) is made from a flexible material which in essence transforms the hopper into a diaphragm-like structure which expands outward in response to the temporary pressure increases. This movement breaks up any dust that may have hardened or caked onto the hopper. This flexible-wall, diaphragm-like structure also provides the additional advantages of deadening the sounds of the cleaning pulses and expanding the volume of the dirty-air chamber, thus allowing the air pulses to act more vigorously on the filters.

Claim 1, the only claim on appeal, reads, with insertion of reference numerals in brackets, as follows:

An air filter assembly for filtering air laden with particulate matter, said assembly comprising:

a housing having a clean air chamber and a filtering chamber , said housing having an upper wall , a closed bottom , and a plurality of side walls [17, 62] depending from said upper wall ;

a clean air outlet from said clean air chamber in one of said side walls ;

a dirty air inlet to said filtering chamber positioned in a wall of said housing in a location generally above said clean air outlet ;

means separating said clean air chamber from said filtering chamber including means mounting a plurality of spaced-apart filter elements within said filtering chamber , with each of said elements being in fluid communication with said air outlet ;

pulse-jet cleaning means , intermediate said outlet and said filter elements , for cleaning each of said filter elements ; and

a lowermost portion in said filtering chamber arranged and constructed for the collection of particulate matter, said portion having means , responsive to pressure increases in said chamber caused by said cleaning means , for moving particulate matter in a downward direction to a bottommost point in said portion for subsequent transfer to a location exterior to said assembly . [Emphasis ours.]

B. The Board Decision

In its initial January 30, 1991 decision, the Board relied solely upon the dust collector disclosed in U.S. Patent No. 3,421,295 (Swift patent) to affirm the Examiner's rejection of claim 1. The Board did not find the secondary references relied upon by the Examiner ² necessary to sustain the rejection. Swift's dust collector, illustrated below by Fig. 2 of the Swift patent, uses pulses of compressed, high-energy gas to counteract normal filter flow. These pulses of compressed gas dislodge particulate matter from spaced-apart filter elements (14), and the dislodged particulate matter moves towards the bottom of the hopper (16).

NOTE: OPINION CONTAINS TABLE OR OTHER DATA THAT IS NOT VIEWABLE

At page 5 of its initial decision, the Board noted Donaldson's arguments that Swift fails to disclose the use in its dust collector of a flexible surface which flexes in response to the gas pulses therein, but stated that:

while such a flexible sloping surface is a recited feature of the apparatus of claims 2, 3, and 5, this is not the case as to the apparatus of claim 1. Thus, [Donaldson's] argument is of no moment to claim 1. Moreover, we are convinced that hopper 16 of the gas filtering apparatus of Swift is "responsive" to pressure increases in the apparatus caused by the jet-cleaning means whereby filtered particulate matter is caused to move in a downward direction. Thus, we agree with the examiner that there is no apparent distinction between the "lowermost portion" of the apparatus recited in claim 1 and the corresponding portion of the apparatus of Swift.

Thus, the Board did not interpret the "means, responsive to pressure increases in said chamber caused by said cleaning means, for moving particulate matter in a downward direction" language recited in the last paragraph of claim 1 as limited to the flexible wall, diaphragm-like structure disclosed in Schuler's specification, and equivalents thereof. Indeed, the Board specifically stated at page 2 of its decision on reconsideration mailed April 17, 1991:

It is axiomatic that particular features or limitations appearing in the specification are not to be read into the claims of an application. [citations omitted] Thus, contrary to [Donaldson's] argument, a flexible sloping surface is not a feature of the air filtering apparatus of claim 1 which distinguishes it over the air filtering apparatus of Swift.

C. Donaldson's Assertions

For purposes of this appeal, Donaldson effectively concedes that Swift teaches or suggests each and every element of the apparatus recited in Schuler's claim 1 except for the "means, responsive to pressure increases in said chamber caused by said cleaning means, for moving particulate matter in a downward direction" recited in the last segment of claim 1. As to this limitation, Donaldson argues that the Board erred in holding that Swift teaches or suggests such a means as it is described in Schuler's specification. Donaldson further argues that the Board's error in this regard is the result of a fundamental legal error by the Board, namely the Board's failure to obey the statutory mandate of 35 U.S.C. Sec. 112, paragraph six, in construing this claim.

II. DISCUSSION

A. Standard of Review

Obviousness under section 103 is a question of law that this court reviews de novo. In re Woodruff, 919 F.2d 1575, 1577, 16 USPQ2d 1934, 1935 (Fed.Cir.1990). Similarly, our precedent is that claim construction, when, as here, there are no underlying factual issues, is also a question of law that we review de novo. Kalman v. Kimberly-Clark Corp., 713 F.2d 760, 771, 218 USPQ 781, 789 (Fed.Cir.), cert. denied, 465 U.S. 1026, 104 S.Ct. 1284, 79 L.Ed.2d 687 (1984). In this case, the PTO erred in its construction of the "means-plus-function" language recited in the last segment of Schuler's claim 1, and this error consequently led the PTO to impose an improper obviousness rejection.

B. 35 U.S.C. Sec. 112, Paragraph Six

When statutory interpretation is at issue, the plain and unambiguous meaning of a statute prevails in the absence of clearly An element in a claim for a combination may be expressed as a means or step for performing a specified function without the recital of structure, material, or acts in support thereof, and such claim shall be construed to cover the corresponding structure, material, or acts described in the specification and equivalents thereof. [Emphasis ours.]

expressed legislative intent to the contrary. See Mansell v. Mansell, 490 U.S. 581, 592, 109 S.Ct. 2023, 2030, 104 L.Ed.2d 675 (1989); Hoechst Aktiengesellschaft v. Quigg, 917 F.2d 522, 526, 16 USPQ2d 1549, 1552 (Fed.Cir.1990). The statutory language at issue in this case reads:

35 U.S.C. Sec. 112, paragraph 6 (1988).

The plain and unambiguous meaning of paragraph six is that one construing means-plus-function language in a claim must...