Julie Research Laboratories, Inc. v. Guildline Instruments, Inc.

• Decision Date: 22 July 1974
• Docket Number: D,No. 471,471
• Citation: 183 USPQ 1,501 F.2d 1131
• Parties: JULIE RESEARCH LABORATORIES, INC., Plaintiff-Appellee, v. GUILDLINE INSTRUMENTS, INC., Defendant-Appellant, and Hallmark Standards, Inc., Defendant. ocket 73-2116.
• Court: U.S. Court of Appeals — Second Circuit

Page 1131

501 F.2d 1131

183 U.S.P.Q. 1

JULIE RESEARCH LABORATORIES, INC., Plaintiff-Appellee, v. GUILDLINE INSTRUMENTS, INC., Defendant-Appellant, and Hallmark Standards, Inc., Defendant.

No. 471, Docket 73-2116.

United States Court of Appeals, Second Circuit.

Argued March 11, 1974.

Decided July 22, 1974.

Lawrence Rosenthal, New York City (Harold I. Kaplan and Blum, Moscovitz, Friedman & Kaplan, New York City, of counsel), for defendant-appellant.

Eliot Gerber, New York City (Wyatt, Gerber & Shoup, New York City, of counsel), for plaintiff-appellee.

Before MANSFIELD and TIMBERS, Circuit Judges, and DAVIS, Judge. ^*

DAVIS, Judge:

After a bench trial in this patent infringement action, the District Court upheld the validity of Patent No. 3,454.877 (issued in July 1969 to Loebe Julie), and ruled that defendant-appellant Guildline Instruments, Inc., had infringed claims 1, 5, 8 and 9. The patent relates to a potentiometer, a device for measuring an unknown voltage by producing a known voltage for comparison with the unknown voltage, and covers 'Potentiometer Means for Providing a Standardized Precision Low Voltage.' Plaintiff-appellee Julie Research Laboratories, Inc., owner of the patent by assignment, manufactures and sells precision measurement devices, including a potentiometer embodying the invention set forth in the patent. Guildline Instruments markets potentiometers (and other precision instruments) made in Canada and imported into this country. ¹ The challenge on appeal is levied against both the holding of validity and the finding of infringement. We reach only the issue of validity.

The technique of potentiometry goes back for well over a century, and has had a number of applications and uses. In the usual classification, potentiometers fall into two modes. In the first a constant current is applied to a variable resistor; changing the resistance permits production of varying known voltages for comparison with the unknown voltage which it is desired to gauge. The second mode reverses the process by calling for application of a variable current to a constant resistor; changing the current permits production of varying known voltages to compare with the unknown voltage. An accepted method of comparison between the known and the unknown voltages is to use a sensitive meter which will read 'zero', or indicate a 'null' condition, when the known voltage equals the unknown. That is because, in that condition, no current flows in the circuit. As the trial judge put it: 'In effect, the known voltage produced by the potentiometer and the voltage of the unknown source cancel each other.'

One consistent effort over many years has been to develop ever greater accuracy in these instruments, and in relatively recent times there has been keen competition to achieve accuracy up to very small fractions of a microvolt. Precise measurements of direct current at this very low level are needed in several activities, including the space program, some other aspects of electronics, and parts of the chemical industry. The Julie patent before us concerns such a microvolt potentiometer for measuring direct current. It exemplifies the first mode described above-- a constant current source applied to a variable resistor.

Very generally, the four claims in issue use a 'feedback' type of constant current source supply presenting an essentially infinite impedance, ² and a transfer means such as a voltage-divider or possibly a series of resistors, permitting the operator, by using fixed input impedance and variable output impedance, to pass varying (but known) amounts of voltage through a constant resistor; the unknown voltage to be measured is connected to the point where the known voltage is introduced to the constant resistor; the transfer device's variable output impedance can be employed to vary the known voltage until it matches the unknown voltage on the 'null' dial and thus reveals the latter's measurement.

It is unnecessary to canvass separately each of the claim components because it is clear, and in effect admitted, that several of them are old, not new. It can also be agreed, at least for purposes of this decision, that the patent device was not wholly anticipated in the prior art. The real struggle is over non-obviousness, and that tussle relates only to two of the elements. Julie Research, representing the patentee, urges non-obviousness on the basis of the combination of (a) use of the feedback source of current, connected with (b) a transfer means using fixed input impedance and variable output impedance. ³ Guildline, the alleged infringer, says that both of these elements are obvious in view of the prior art, that their combination with each other and the other components is also obvious, and therefore that the claims are all invalid under 35 U.S.C. 103.

On the first aspect-- the feedback current source-- the record shows conclusively that a feedback-type source of constant current was predicted, known, and actually used in potentiometry well before Julie's patent application in July 1965. Feedback-type constant source generators have been available for at least twenty years, but only in the early 1960's were they developed sufficiently for use in microvolt potentiometers. In 1961-62, Dr. Dauphinee, a recognized potentiometry expert, expressed the need for better constant sources and specifically referred to the probable use of feedback systems 'for stabilizing potentiometer currents.' In 1963 Julie Research and Guildline both offered feedback sources (with essentially infinite impedance) for use in potentiometry. ⁴ The record also suggests that in the same year Minneapolis-Honeywell marketed such a source for one of its potentiometers. In an article prepared in 1964 and published early in March 1965, Dr. Dauphinee wrote that the problem of current stability needed reevaluation 'now that current controllers capable of six-figure regulation for substantial periods and seven-figures over limited periods of time are starting to come on the market.' It seems to us obvious that in 1964 and 1965 it would have been obvious to one skilled in the art of potentiometry to use such feedback-type generators, instead of batteries (with adjusters) or other constant current sources, in an instrument designed as a microvolt potentiometer. The District Court's findings do not expressly touch on the obviousness of the use of a feedback source, but if they are read to find implicitly that such use was non-obvious in 1964 or 1965 they are clearly erroneous on this record.

The rub of the case comes with the second alleged novel-unobvious feature of the claims-- a transfer means using fixed input impedance and variable output impedance. To show that this too was obvious in the light of the prior art, Guildline has proffered a reference not considered by the Patent Office, the potentiometer element or ring proposed by Diesselhorst in Germany in 1906. This ring, like the Julie patent, teaches a constant current source, output terminals of a device acting as a voltage divider, a constant or fixed resistor, and input terminals of the voltage divider.

The court below accepted the views of the patentee's witnesses that Diesselhorst discloses a transfer means having a variable input impedance and fixed output impedance, rather than Guildline's witnesses' contrary position. The court considered the issue purely one of 'credibility', citing only factors of demeanor and comparative qualifications; the findings contain no discussion of the substantive or scientific merits of the issue. We do not take that stance. The question should not turn simply on the external indicia of 'credibility'-- as if some ordinary fact like the date of a telephone conversation were involved-- but on analysis of the drawings and documents in the light of the help of the expert testimony.

On that basis, Guildline seems to us clearly right. Everyone agrees as to the physical structure of the Diesselhorst ring-- including an inner ring of resistors, nine divider resistors of the outer ring, and a tenth load resistor of the outer ring. The experts' difference lies solely in their characterization of the various resistors in the process of determining whether the input impedance of the transfer means is fixed or variable. Julie Research's witnesses counted as part of the transfer means the inner ring of resistors, along with the nine divider resistors and the additional load resistor, in coming to the conclusion that the input impedance was variable. Guildline's experts excluded the inner ring resistors and the load resistor, basing their calculations on the nine resistors of the outer ring as constituting the transfer means.

This latter position is correct because it is plain that the inner ring of resistors is not part of the transfer means and has an entirely different function having to do with maintenance of a constant source of current. Since Diesselhorst contemplated batteries as the source and a battery's current production varies with load conditions, it was necessary to provide a compensating device; the inner ring resistors fulfilled this purpose, adjusting the current supplied by the battery to the transfer means of the potentiometer so that the current would be maintained at a constant level. ⁵ The Julie patent, having its own constant feedback source, does not need such compensators; Prof. Abramowitz, the leading expert for ...