Court Opinion

ID: 6899034
Source: CourtListenerOpinion
Date Created: 2022-07-23 21:53:00.684821+00
Date Added: 2024-06-11T16:06:06.460255
License: Public Domain

MAGRUDER, Circuit Judge
(dissenting).
It is an act of temerity to express disagreement with an opinion by Judge Wood-bury in a patent case. But I can’t see anything in the defendant’s accused magnetic chuck other than a clever adaptation of the principle of the Bower chuck as improved by Bing and Block.
If I understand the record aright, there was really no conflict of evidence below as to what happens when the rotatable central magnet of the Walker chuck is turned from the “on” to “off” position, but only differences in the language used to describe the result. In Exhibit 19, a drawing of the Walker chuck, when the central cylindrical magnet is in the “on” position, the north poles of the three magnets are in upward alignment, and the work-pieces are firmly held by force of flux circuits running from the north poles of the magnets through the upper pole pieces, through the work-pieces, and back to the south poles through the upstanding legs and base portions of the lower pole pieces.' When the central magnet is rotated to “off” position, so that its south pole is now upward, in alignment with the north poles of the two fixed magnets, the work-pieces are released because the flux, with magnetomotive force undiminished, has been diverted from the work-pieces into alternate circuits. That is, the flux from the north pole of the left-hand fixed magnet now passes through the upper pole piece, through the central magnet, thence through the lower pole piece back to the south pole; the flux from the *694north pole of the right-hand fixed magnet follows a corresponding course; the flux from the north pole of the central magnet divides, some of it passing through the pole piece and the left-hand fixed magnet and back again to the south pole of the central magnet, the remainder of its flux following a corresponding course through the right-hand fixed magnet. The foregoing was substantially conceded by defendant’s expert witness.
The court, I think, has attached undue importance' to the words “shunt” and “shunting”, referring to a portion of the testimony of defendant’s expert to the effect that in Walker’s chuck the work-pieces are not released “primarily by shunting, but primarily by balancing opposing magnetomotive forces — by putting balanced magnets in opposition to one another — a wholly different principle of operation from that taught by Bower and Bing and Block.” So far as I am aware, “shunting” is not a word of art, and means no more than shifting or diverting. The claims in issue put no special emphasis on this particular term. Neither “shunt” nor “shunting” appears in claims 1 and 4 of Bing and Block, nor in claim 7 of Bower. In fact, the court, in summarizing all the claims in issue, does not use the word “shunt”, but describes the claims, accurately, I believe, as covering the “release of a work-piece by a relative movement of parts whereby an auxiliary magnetic circuit is created to divert the flux of permanent magnets away from the surface of the chuck and the work-piece thereon through a path or circuit within the chuck itself.” The Walker chuck fits this language like a glove. The correspondence is even more sharply evident by reference to the exact language of Bower’s claim 7:
“A magnetic chuck, comprising means for creating a magnetic field, a work supporting member disposed in said magnetic field and having portions of relatively high and relatively low permeability, and means for selectively adjusting said work supporting member relatively to said magnetic field whereby to cause the magnetic flux to pass through the work on the chuck to hold said work in position to be operated upon, said means being shiftable to establish an auxUicury circuit to cause the magnetic flux to be diverted from the work while the work remains in the normal magnetic work holding zone to release the work from the chuck." [Italics added.]