APPLICATION OF MERGNER

• Decision Date: 03 July 1968
• Docket Number: Patent Appeal No. 7971.
• Citation: 399 F.2d 231
• Parties: Application of Fritz L. MERGNER.
• Court: U.S. Court of Customs and Patent Appeals (CCPA)

399 F.2d 231 (1968)

Application of Fritz L. MERGNER.

Patent Appeal No. 7971.

United States Court of Customs and Patent Appeals.

July 3, 1968.

Henry L. Burkitt, New York City, for appellant.

Joseph Schimmel, Washington, D. C. (Jere W. Sears, Washington, D. C., of counsel), for the Commissioner of Patents.

Before WORLEY, Chief Judge, and Judges RICH, SMITH, ALMOND, and KIRKPATRICK.^*

ARTHUR M. SMITH, Judge.

When tested according to the statutory requirements of 35 U.S.C. § 103, appellant's claimed subject matter¹ here appealed would not, in our opinion, have been obvious at the time the invention was made. Thus, the decision of the Patent Office Board of Appeals² is reversed.

The invention relates to recording systems for recording and reproducing electrical signals. An object of the invention is to reduce materially the number of amplifying circuits, filter and network components used in a magnetic recording and reproducing system.

In accordance with the invention, a magnetic tape recording system is provided with an internal switching and control circuit which permits amplifiers, networks, filters and control circuits located ahead of the recording head to be used also in the playback mode by switching into the circuit a feedback circuit located between the playback head and a signal source selector for the recorder. Fig. 1 is reproduced below:

That figure depicts a recorder system 1 having its internal switches set for the recording mode with the source selector switch 10 in the "tuner" position. In a recorder³ a tape 19 moves between recording head 3 and tape playback head 4. Each head has its own amplifier, shown at 16 and 17. The selected source signal 5 from a tuner is amplified by audio amplifier 6 and passed to recorder 2 either along path A-A when filters 7 and 8 are bypassed, or, alternatively, along path B-B via high-pass filter 7 and low-pass filter 8. With the setting shown in Fig. 1, switches 9 and 9' are set to bypass the filters. The signal from a tuner 5 by switch 10 may thus be recorded on the tape 19.

The recorded signals may be nearly immediately monitored by the tape playback head 4 and amplifier 17, through monitor jack 22 and tape monitor switch 15 to be reproduced from loudspeaker 20, characterized in the claims as a transducer. A tone control circuit 11, volume control circuit 12 and power amplifier 13 are disposed intermediate the loudspeaker 20 and tape monitor 15.

When in the playback mode, switch 10 is connected to the "tape play" terminal inserting the feedback loop 21 and filter 23 into the circuit. The tape monitor switch 15 is switched to its "off" position so that the signals intercepted on tape 9 by the tape playback head are passed via amplifier 17, monitor jack 22, feedback loop 21, filter 23, either circuit A-A or circuit B-B, as desired, including audio amplifier 6 and the output circuit, i. e., tone control circuit 11, volume control circuit 12, power amplifier 13, for reproduction by loudspeaker 20. Thus, during recording, amplifiers 6 and 16 are used; during monitoring, amplifiers 17 and 13 are used; and for playback, amplifiers 17, 6 and 13 are used.

Claims 12 and 18 are representative of the appealed claims:

12. The combination with a tape recorder including a recording head, a playback head, means for moving a tape past the heads, each of the heads having its own amplifier, means for supplying a signal to the recording head, and a transducer; of a secondary circuit including filter and amplifying means, means associated with the secondary circuit for determining the effectiveness of the filter means, a feedback circuit, means operative when the tape recorder is set for recording to connect the signal supplying means to feed its signal through the secondary circuit and the recording head amplifier to the recording head while making the feedback circuit ineffective, means for passing a signal derived by means of the playback head from the moving tape through the playback head amplifier to the transducer, and means operative when the tape recorder is set for playback to feed the derived signal through the playback amplifier, the feedback circuit and the secondary circuit to the transducer. (Emphasis added.)

18. The combination with a tape recorder including a recording head, a playback head, means for moving a tape past the heads, means for supplying a signal for the recording head, and a transducer; of a secondary circuit including amplitude and frequency control means and amplifying means, means associated with the secondary circuit for determining the effectiveness of the secondary circuit, a feedback circuit, means operative when the tape recorder is set for recording to connect the signal supplying means to feed its signal through the secondary circuit and the recording head while making the feedback circuit ineffective, and means operative when the tape recorder is set for playback for feeding the signal obtained from a tape moving past the playback head through the feedback circuit and the secondary circuit to the transducer. (Emphasis added.)

Claim 11 is comparable in scope to claim 12, while claim 19 most nearly resembles claim 18 in scope.

The appealed claims were rejected under 35 U.S.C. § 103 as "unpatentable over" a reference patent to Bobb.⁴ The Bobb patent also relates to magnetic recording and reproducing circuits. Fig. 1 of the reference depicts a block diagram of that invention:

The examiner's description of the Bobb reference is generally adequate for our purposes; thus we quote it at some length:

Figure 1 of Bobb shows a block diagram of the magnetic recording and reproducing apparatus. A selector switch A is provided to alternatively connect one of the three external signal sources (in the recording mode) or the magnetic head (in the playback mode) to the preamplifier and frequency compensation section of circuit B.

* * * * * *

In the recording mode, the signal is passed from circuits B to network E, which may have the characteristics of passing the audio frequencies and blocking other frequencies. The signal is then passed through a phase inverter F, amplifier tubes V1, V2, network L (which has a rising transmission characteristic with frequency), a bleeder network M, switch M (sic), switch N, and then to magnetic head O which records the signal on a magnetic tape (not shown).

* * * * * *

* * * To change to the playback mode, switch A is switched to connect conductor P to preamplifier B and switch N is changed so that the magnetic head O is connected to conductor P and acts as a playback head.

In the playback mode, the recorded signal is sensed by the

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