Application of Nygard

• Decision Date: 04 March 1965
• Docket Number: Patent Appeal No. 7324.
• Citation: 341 F.2d 924
• Parties: Application of John C. NYGARD.
• Court: U.S. Court of Customs and Patent Appeals (CCPA)

341 F.2d 924 (1965)

Application of John C. NYGARD.

Patent Appeal No. 7324.

United States Court of Customs and Patent Appeals.

March 4, 1965.

Henry C. Nields, Burlington, Mass., Dos T. Hatfield, Washington, D. C., for appellant.

Clarence W. Moore, Washington, D. C. (Jere W. Sears, Washington, D. C., of counsel), for Commissioner of Patents.

Before WORLEY, Chief Judge, and RICH, MARTIN, SMITH and ALMOND, Judges.

RICH, Judge.

This is an appeal from the decision of the Board of Appeals rejecting all claims, 1-5, of appellant's application serial No. 782,708, filed December 24, 1958, entitled "Non-Linear Inductance."

The Invention

The invention is in the field of electronics and, notwithstanding the title of the application, is claimed as "A charging circuit for a pulse-forming network." The "inductance" referred to in the title is part of that charging circuit. The specification does not disclose the use of the pulses produced by the network which is charged by the charging circuit nor does appellant's brief enlighten us in that regard, but one use would appear to be in radar.

The pulse-forming and charging circuit is schematically represented in the specification in highly simplified form in Fig. 1, thus:

This shows a pulse-forming network 1 comprising a series of capacitors 2 arranged in parallel between load 3 and various points on an inductance 4. A thyratron, which is a gas-filled three-element electron tube, is schematically represented as a switch 6 connected between the high-voltage end of network 1 and ground so that when the thyratron 6 is triggered it grounds the network. whereupon the capacitors discharge through the inductance 4, providing a current pulse through the load 3 which may be a square wave current pulse.

The charging circuit for the pulse-forming network comprises a d. c. voltage source 5 connected to the network 4 through an inductance 7 and a diode or rectifier 8. It is said to operate according to the principles of resonance charging, which appears to be a known phenomenon which is thus described in appellant's brief:

"* * * The unidirectional property of the diode 8 and the characteristics of the reactor 7 which oppose any change in current flow combine to effect charging of the capacitors to a voltage equal to twice the voltage of the direct current source. * * *"

All of the foregoing appears to have been known in the art. However, a problem existed which is described in appellant's brief as follows:

"* * * Reliable switching in such a system becomes a problem, however. In order for a thyraton switch to change from a conducting to a non-conducting state, its plate current must fall below a given threshold value; a condition which does not necessarily exist after each switching operation of the prior art pulse forming network. * * *"

The reason for the lack of reliability is described in the specification as follows:

"* * * It will be apparent that as soon as the pulse-forming network is fully discharged the valve tube 8 will act to initiate the charging from the d. c. voltage source, and frequently the result is that the pulse-forming network will start to be charged before the thyratron 6 switch mechanism has returned to the necessary original state. * *"

Appellant's invention is a change in the characteristics of inductance 7, which is also known as the "charging reactor," whereby the charging of the pulse-forming network 1 is delayed sufficiently to assure that the thyratron 6 has returned to its stable or open-circuit state before charging starts, presumably so that the charging circuit will not be connected to ground through the thyratron in a conducting state.

One way of doing this is described in the specification and drawing thus:

"In accordance with the invention a non-linearity is introduced into the inductance 7 as shown in Fig. 3."

"For example, said inductance 7 may comprise an iron core 9 including as a part of its magnetic circuit a saturable material 10, such as ferrite or some similar product. As a result, at low currents the iron core 9 has a high inductance, but as higher currents are reached, so that the ferrite or other material saturates, the iron core acts as though it had an air gap in it, since the ferrite is no longer acting as part of the low-reluctance magnetic circuit. The inductance at these higher-current values would then be inversely proportional to the length of the high-reluctance `gap\'. The effect of providing such a saturable material in the iron core 9 of the inductance 7 is shown by the broken line in the graph of Fig. 2 which shows a time delay in the rise of charging voltage. At first the inductance in the iron core 9 is relatively high, thereby opposing the flow of current so that the current remains low. However, when the saturable material 10 becomes saturated, the inductance is decreased by an amount which is proportional to the thickness of the saturable material 10. As a result of this reduction in inductance, the current flow is permitted to increase in the normal manner. The overall effect of the addition of the nonlinear inductance is to delay the charging of the pulse-forming network 1, thereby permitting the thyratron switch 6 to return to its stable state."

Appellant discloses a second embodiment of his invention wherein he uses, instead of the Fig. 3 core with ferrite insert, an inductance with two coils in series each having its own core, one core reaching saturation at an early point in the cycle while the other does not, thus producing the same effect with different means.

The Rejections

The examiner rejected the claims for reasons unknown to us, citing as references three prior United States patents which are not in the record before us and which we need not consider because the board disagreed with the examiner and refused to sustain his rejection. For this reason the record contains no examiner's actions and no examiner's answer; the appellant prevailed before the board in having the examiner reversed.

In his brief before the board, appellant called attention to "page 12 of Vol. 5 of the Radiation Laboratory Series concerning resonance charging of pulse forming networks," as stated in the board's opinion. The board cited a new reference as follows:

Reference cited by the Board of Appeals:

Pulse Generators, Vol. 5, Radiation Laboratory Series, page 341 and pages 364, 365 and 366

This is the only prior art of record before us — four pages of what appears to be a book of several hundred pages. That book, as such, is not of record nor have we been furnished a copy.

After citing and discussing the four pages above mentioned, the board made the following rejection:

"* * * Therefore, under the provisions of Rule 196(b) we hold that claims 1 to 5, inclusive are unpatentable over the disclosure in Vol. 5 of the Radiation Laboratory Series.

"The decision of the Examiner is reversed.

"A new rejection of claims 1 to 5, inclusive, under the provisions of Rule 196(b) is made."

Appellant filed a request for reconsideration and argument but the board fully adhered to its position.

The Claims

Claim 1 reads:

"1. A charging circuit for a pulse-forming network, comprising, in combination with a pulse-forming network: a source of d. c. voltage and an inductor linking magnetic material comprising two components which saturate at mutually different applied magnetomotive forces x connected in series between said d. c. voltage and said pulse-forming network y, the

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