Justia Federal District Court Opinions

Renishaw PLC ("Renishaw") is the owner of U.S. Patent Nos. 4,153,998 (the '998 patent) and 4,270,275 (the '275 patent), both directed to "touch-trigger" probes used in coordinate measuring machines. Renishaw appeals the judgment of the United States District Court for the Southern District of New York, entered after a bench trial in consolidated declaratory judgment and infringement actions, in favor of Carl Zeiss Stiftung and Carl Zeiss, Inc. (collectively, "Zeiss"), holding that Zeiss' products do not infringe claims 2 or 15 of the '998 patent or claim 1 of the '275 patent, and also holding that claim 3 of Renishaw's '275 patent is invalid as lacking utility under 35 U.S.C. § 101 and claim definiteness under § 112, and as obvious under § 103. Carl Zeiss Stiftung v. Renishaw PLC, 740 F.Supp. 1038, 18 USPQ2d 1817 (S.D.N.Y.1990). Because the court's alternative grounds for holding claim 3 invalid are erroneous, and because the court misconstrued claim 2 in such a way that its finding of no infringement is clearly erroneous, we reverse. The case is remanded for determination of damages as to claim 2, and for adjudication of any other issues properly raised by the parties that are not moot.

BACKGROUND

The patents in suit relate to the technology of coordinate measuring machines ("CMMs"), devices for measuring the dimensions of objects to extremely fine precision. In a typical CMM, a probe containing a stylus is mounted to a movable arm above a table which supports an object to be measured. A control means in the CMM continuously monitors movement of the probe in the three coordinate directions, so that the precise location in space of the stylus tip is at all times determined to great accuracy. To make a measurement, an object is mounted on the CMM table, and the probe is moved towards the object until the stylus attached to the probe makes contact with the object. The coordinates of the stylus tip at the point of contact are recorded, thus giving a measurement of the position of one point on the surface of the object. The probe is then repositioned and moved towards another point on the object, this procedure being repeated a number of times until all such measurements as are necessary have been made. From the coordinates of the various points at which the stylus tip contacted different surfaces of the object, the dimensions of the object can be calculated by a computer. A CMM may be operated manually, or the features described may be automated for ease of use.

Accurate measurement by a CMM requires an accurate means to determine the precise point in space at which the stylus tip makes contact with the object to be measured. In addition, in an automated CMM the probe movement must be halted as quickly as possible upon contact with the object so that the stylus does not "overtravel," i.e., continue moving against the object, potentially damaging the object and/or probe, before the computer controlling the CMM can stop movement. For both of these reasons, it is crucial that the probe signals the CMM's computer as quickly as possible when the stylus makes contact with the object to be measured.

Formerly, CMMs were operated by hand and used "hard probes," with a stylus rigidly mounted on the probe. Though inexpensive and satisfactory on manually operated CMMs, hard probes proved not to be as well-suited for use in the automated CMMs that were eventually developed because their rigid styli can easily cause damage to the probe or to the object being measured when the probe arm overtravels (as it always does). The development of automated CMMs thus created a need for a different type of probe.

In the early 1970s, David McMurtry invented the device which is the subject of the patents at issue here. McMurtry's "touch-trigger" probe solved many of the problems associated with hard probes, satisfied a long-felt need in the precision measuring industry, and has been an enormous commercial success. The company that McMurtry founded to commercialize his invention, Renishaw, sells large numbers of its touch-trigger probes to CMM manufacturers throughout the world.

McMurtry's touch-trigger probe utilizes a stylus which can move slightly within its mount, allowing for deflection upon contact with an object. Convergent surfaces, which fit together precisely when the stylus is in its rest position, establish a "kinematic mount": deflection of the stylus away from the rest position disturbs the seating of the convergent surfaces, sending a signal to the CMM that contact has been made.

In one embodiment of the McMurtry invention, depicted below in Fig. 1 (Fig. 1 of the '998 patent specification, with descriptive labels added), the stylus is mounted on a movable member which is urged into place against a fixed member by means of a spring. When the movable member is thus seated against the fixed member, an electrical circuit is completed at the convergent surfaces, allowing a current to flow. When the stylus makes contact with an object being measured, the movable member deflects against the force of the spring, breaking the electrical circuit at the convergent surfaces and sending a signal to the CMM indicating that contact has occurred. The coordinates of that contact point are then sent to the CMM's computer and recorded. Upon cessation of contact, the movable member is precisely and repeatably urged back to its rest position so that the convergent surfaces are again properly seated and the electric circuit is completed, ready for the probe to make another contact.

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