Gordon1 appeals from the decision of the Board of Patent Interferences which awarded priority of invention of the subject matter set forth in the following count to the senior party, Hubbard and Fosdick:2

1. A potentiometric device comprising a casing having a support block, a resistance element and a conductor bar in parallel spaced relationship and fixed to said support block, a travel block having means directly slidable upon said support block, a contact element secured to said travel block and slidably engaging said resistance element and said conductor bar, and means engaging said travel block for imparting linear motion thereto.

The nature of the screw-actuated potentiometric device is indicated by a drawing taken from the Hubbard patent:

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As illustrated, the potentiometer includes a U-shaped base member 1 having a support block 4 disposed between the upright ends 6. The block 4 has parallel, spaced-apart shoulders 20 and 21 on each side, and parallel resistance and conductor elements 13 and 14 mounted in parallel, spaced-apart relation between and alongside the shoulders. A travel block 22 has depending shoulders which ride on the support block shoulders. A contact brush 24 is affixed to the travel block's lower side to slidably engage both the resistance and conductor elements. A lead screw 27 rotatably supported by the upright ends of the base is threaded through the travel block to move it and the contact element along the resistance and conductor elements. The inside surfaces of a U-shaped cover 2 act as guides for the travel block as it is moved linearly by rotation of the lead screw.

Gordon's device is reflected in the following drawings:

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It, too, is a linear potentiometer having a U-shaped body 10 with parallel resistance and conductor elements 20 and 21 supported on a central support portion 11. A travel block 17 is engaged by an adjustment shaft 16, which is rotatably supported between the ends of the body 10. The travel block carries contact element 28 which slidably engages both the resistance and conductor elements. The block 17 has downwardly extending runners 33 and 34 on opposite edges which slidably engage the edges of the support block portion 11 outwardly of the resistance and conductor elements. An open-ended case 68 slides into position enclosing the potentiometer. The device is said to have over-all dimensions less than 5/16" by 5/16" by 1¼".

Appellant asserts that the invention in issue constitutes an improvement in potentiometric devices which were well known in the art prior to filing of either of the present applications. The record seems to support appellant's contention that the particular novelty of the article of the count lies in the recitation "a travel block having means directly slidable upon said support block," corresponding to runners 32 and 33 in the illustrated device of Gordon, and the depending shoulders in Hubbard's device. It is those shoulders or runners which are said to secure the travel block against transverse or rotational movement as the lead screw is turned, thus insuring freedom from vibrational distortion as well as providing good electrical contact between the brush and the resistance and conductor elements.

Hubbard relies primarily on his filing date of February 3, 1956, for constructive reduction to practice. Gordon makes no claim of diligence from a date prior to Hubbard's filing date until any later actual reduction to practice or his own filing date of May 10, 1956. The principle issue before us is whether Gordon has proved by a preponderance of the evidence that he reduced the invention to practice prior to Hubbard's filing date.

The board, in considering the testimony of Gordon's witnesses3 and related exhibits, found the record

* * * clearly establishes that at least by the period of time in November-December of 1955, several potentiometric devices meeting the terms of the count in issue had been assembled by Borbor or by Borbor in collaboration with Waldron. * * *

The board, however, found the record on behalf of Gordon

* * * so devoid of proof with respect to tests of a completed potentiometer, including one having a "casing" as required by the count in issue, "as part of some practical apparatus" under "conditions normally encountered in at least one such use" * * * that it fails to establish actual reduction to practice.

citing Elmore v. Schmitt, 278 F.2d 510, 47 CCPA 960, to support its holding.

In reaching that conclusion, the board noted that the count in issue does not set forth any particular purpose or use of the potentiometric device, and it turned to the Gordon specification for statements4 which shed light on that matter. See Landon v. Ginzton, 214 F.2d 160, 41 CCPA 950. There it found:

This invention relates to potentiometers or variable resistors for use in electrical circuits and in particular to potentiometers which are adapted for use in miniaturized equipment.

It is an object of the invention to provide a miniature potentiometer which is small in size and stable in operation under extremes of vibration, shock, atmospheric pressure, temperature and humidity. A further object of the invention is to provide such a potentiometer which is simple in design and inexpensive to produce and test and which is well adapted to automatic methods of manufacture.

It is another object of the invention to provide a miniature potentiometer which is completely assembled and tested before being placed in its case and which may be mounted with a plurality of similar potentiometers in horizontal and/or vertical rows, either with or without the cases for the individual potentiometers. Another object of the invention is to provide a miniature potentiometer in which the moving element is translated by means of a rotating threaded shaft with the shaft being manually operable from the end of the potentiometer by a screw driver or the like.

It is a further object of the invention to provide a miniature potentiometer which may be sealed in its case to minimize the entrance of dust and moisture with the openings for the electrical terminals being closed by solder and with the opening for the adjusting shaft being sealed by a labyrinth bearing structure. Another object of the invention is to provide a miniature potentiometer suitable for use with resistance elements which are fired on ceramic bases as well as with wound or molded resistance elements.

* * * * * *

Means are carried on the contact block 17 for electrically connecting a point on the resistance element 20 with the conducting element 21. A preferred form for this connecting means which provides positive interconnection under extreme conditions of vibration and shock without requiring a complicated structure or precision contact surfaces is illustrated in Figs. 2 and 3. * * * [Emphasis supplied].

The board then reviewed in extenso the testimony of the witnesses which, in its opinion, related to testing of the device. It found

* * * no evidence of any tests at all wherein the potentiometers were subjected to vibrations, shock, high temperature or low temperature either with or without the required casing. At most the evidence shows that tests were made on potentiometers though it is not clear whether they had casings or not, in which the adjusting screw was run back and forth by hand or by motor drive; the bearings were inspected for breaking loose from the support; and the travel block was watched for movement. The sole test that was performed which related to the electrical properties and capabilities of the device was the connection of the potentiometer in an apparently conventional ohmeter, the indicator variations being observed as the adjusting screw and travel block were manipulated. Clearly, the potentiometers were not installed in their intended environment. * * *

In its view, the record failed to show that any of the tests employed accurately reproduced the operating conditions which would be encountered in any practical use of the invention.

Before discussing other aspects of this case, it is necessary to dispose of an initial argument advanced by Gordon. He urges that the board, in construing the count, failed to appreciate the essence of the common invention in issue and that, in holding that the common invention necessarily includes an enclosing cover or "casing," it misapprehended the invention that Gordon must reduce to practice. He contends that the term "casing" in the count is fully met by body 10 and central portion 11 of his device, as well as by base member 1 and support block 4 of Hubbard's device. We think Gordon is in error in his contentions. Hubbard's patent defines his "casing" as "composed of a male base member 1 * * * and a female cover member 2." Gordon's application refers to element 68, shown in the above drawings, as "an open-ended case," and Borbor identified an identical element in Gordon's record exhibit J as "the case, or as it is called here, cover of the instrument." In our view, the term "casing," which is part of the potentiometer recited in the count, necessarily includes a "cover."

In all of the cases in which this court has reviewed whether sufficient and proper testing had occurred to establish reduction to practice, we have taken pains to point out that the nature of the testing required depends on the particular facts of each case. A certain amount of "common sense" must be applied in determining the extent of testing required. Depending on its nature, the invention may be tested under actual conditions of use, or may be tested under "bench" or laboratory conditions which fully duplicate each and every condition of actual use, or, in some cases, may be tested under laboratory conditions which do not duplicate all of the conditions of actual use. In instances where the invention is sufficiently simple, mere construction or synthesis of the subject matter may be sufficient to show that it will operate satisfactorily. In all such cases, the evidence must establish a relationship between the subject matter involved, the test conditions and the intended functional setting of the invention. White v. Lemmerman, 341 F.2d 110, 52 CCPA 968; Paivinen v. Sands, 339 F.2d 217, 52 CCPA 906.

We turn, then, to a consideration of the nature of the tests required to establish reduction to practice of the present device. While we are inclined to agree with Gordon that the potentiometers defined by the count are not so complex as to require actual field tests, we cannot subscribe to his view that the present subject matter is of such relative simplicity that mere construction of it is sufficient to establish reduction to practice. Although we do not doubt that potentiometers are useful in the abstract, we think, contrary to Gordon's argument, that the board was correct in not assuming the potentiometers constructed by Gordon are obviously useful simply because they correspond to the terms of the count, for that is not the question in issue. We think the question is whether the bench tests and other evidence demonstrate that Gordon's device, as constructed, was capable of successfully achieving at least one contemplated use so it may be regarded as reduced to practice.

It is, of course, well settled that when an interference count does not specify any particular use, evidence proving substantial utility for any purpose is sufficient to establish reduction to practice. Blicke v. Treves, 241 F.2d 718, 44 CCPA 753. Like the board, however, we regard the present record to be substantially incomplete with respect to evidence of successful testing of a potentiometer, particularly with the "casing" required by the count, under conditions normally encountered in at least one contemplated use. As a minimum, we think the tests performed should demonstrate that the Gordon potentiometers, as a result of the particular novel construction of the travel block, were in fact free from vibrational distortion and brush contact "bounce," i. e. loss of position and poor electrical contact. We have examined all of the testimony,5 particularly that of Borbor, Waldron and Gordon which is included in Gordon's brief. In our view, that testimony as a whole simply relates that tests were performed, and gives no definite indication or suggestion what results were attained or that the results were satisfactory. We have searched the record in vain for clear, unequivocal testimony that tests on the device showed that the shoulders or runners on the travel block did in fact render the potentiometer vibration or shock resistant so as to provide uniform contact between the brushes and the resistance or conductor elements of the device throughout the range of adjustment.

Moreover, when we consider whether the evidence of record has established that the tests actually performed were of a character sufficient to show that the Gordon potentiometers would be successful in the intended functional setting or environment, we think the record again compels a negative conclusion. In addition to the objects and intended uses of the potentiometers set out by each party in the respective applications, we note, as did the board, that Waldron testified that a certain plastic-encased model worked on in December, January and February of 1955 and 1956 "was made for a high temperature, be able to use it in high and low temperature." He acknowledged that those plastic-encased potentiometers, which apparently exemplified the initial models built by Gordon, Borbor and Waldron, would not "hold up very well at all out in the field." Waldron stated that low temperatures would make the plastic "brittle, cold, and if it had to go through any sort of a shock test or vibration test it could crack and expose the elements to salt spray." By the same token, Waldron noted that "this particular model was to be used in high temperature" and, since "plastics at that time would not withstand 400 degrees Fahrenheit" and "get up into the high temperature range," they would "just melt and run." Consequently, the plastic-encased model "was cast aside."

As a result of those problems, Gordon contemplated enclosing the potentiometer with a metal casing or cover. We agree with the board that the record does not show whether such a completed device was tested at all. Gordon argues that it was unnecessary to test a potentiometer having a "cover" of any sort. Apart from our view that the device of the count requires a "cover" as part of the "casing," we think that testing of the device with a cover was necessary here, particularly in view of problems which apparently developed when a metal casing was employed to enclose the potentiometer.6 Although it appears that models using a "Mylar" polyester insulating tape inside the casing were later built or tested, the record does not establish a date therefor.

It would unduly lengthen this opinion to analyze in detail all the testimony of the witnesses which the board and appellant have reviewed at length. Our study of the record with due regard for Gordon's arguments convinces us that the board did not err in awarding Hubbard priority of invention of the subject matter of the count.

The decision is affirmed.

Affirmed.