Headphone type FM stereo receiver

• US 3,906,160 A
• Filed: 07/13/1973
• Issued: 09/16/1975
• Est. Priority Date: 03/19/1968
• Status: Expired due to Term

• Current Assignee: Eizo Mori, Shoichi Nakamura, Tsuneo Okubo, Yoshiteru Onaka
• Original Assignee: Eizo Mori, Shoichi Nakamura, Tsuneo Okubo, Yoshiteru Onaka
• Inventors: Nakamura, Shoichi, Mori, Eizo, Onaka, Yoshiteru, Okubo, Tsuneo
• Primary Examiner(s): Claffy, Kathleen H.
• Assistant Examiner(s): Chin, Tommy P.
• Application Number:
  US05/378,822
• Time in Patent Office: 795 Days
• Field of Search: 179/15BT,1G 325/361,36 333/3,4 350/20
• US Class Current: 381/9
• CPC Class Codes: H04B 1/1646 adapted for the reception of stereophonic signals
• CPC Class Codes: H04R 1/1008 Earpieces of the supra-aural or circum-aural type
• CPC Class Codes: H04R 1/1025 Accumulators or arrangements for charging secondary cells per se H01M10/00; charging in general H02J7/00
• CPC Class Codes: H04R 1/1041 Mechanical or electronic switches, or control elements switches in general H01H
• CPC Class Codes: H04R 2420/07 Applications of wireless loudspeakers or wireless microphones
• CPC Class Codes: H04R 5/033 Headphones for stereophonic communication details thereof, e.g. relating to batteries, cables or control elements H04R1/10

Abstract

A FM stereo receiver in the form of a headphone comprising two phone cases and a head belt bridging said two phone cases, said head belt having accommodated therein a tuner including an antenna for receiving FM stereophonic broadcasting, IF amplifier, a discriminator, a FM stereo signal demodulator, a left and a right audio frequency amplifier and power source means for supplying an electric power to said respective elements, so that FM stereophonic broadcasting may be received solely by said receiver without connecting the receiver with external apparatus.

Claims

1. An FM stereo signal demodulator for FM stereo receivers comprising a first transistor having its base connected to receive an FM stereo signal from said discriminator, a 19 KC tuning coil connected to the collector of said first transistor, frequency multiplying diodes connected to the secondary winding of said tuning coil, a direct coupled amplifier consisting of second and third transistors, the emitter of said third transistor being connected to the base of said second transistor through more than one resistor so as to obtain the bias of said second transistor, and to obtain the negative feedback loop for the amplifier composed of said second and third transistors, and a switchng circuit consisting of four diodes connected in the shape of a ring, the arrangement being such that a signal received by the 19 KC tuning coil is multiplied to a 38 KC signal by the frequency multiplying diodes, the resultant 38 KC signal being impressed on the direct-coupled amplifier to obtain 38 KC outputs of opposite polarities from the emitter and collector of the third transistor, and said 38 KC output being coupled with a stereophonic signal supplied from the first transistor and then impressed on a pair of connections located at opposite ends of one of the diagonal lines of the switching circuit, whereby separated left and right signals are taken out from opposite ends of another diagonal line of said switching circuit.

2. A headphone type FM stereo receiver accommodating a tuner including an antenna for receiving FM stereophonic broadcasting, an IF amplifier, a discriminator, an FM stereo signal demodulator, a left and right audio frequency amplifier and power source means for supplying electric power to said respective elements in a headphone composed of a left and a right phone case and a head belt bridging said phone cases with each other, said receiver being capable of receiving FM stereophonic broadcasting without being connected to an external apparatus, wherein said FM stereo signal demodulator comprises a first transistor having its base connected to receive an FM stereo signal from said discriminator, a 19 KC tuning coil connected to the collector of said first transistor, frequency multiplying diodes connected to the secondary winding of said tuning coil, a direct-coupled amplifier consisting of second and third transistors, the emitter of said third transistor beIng connected to the base of said second transistor through more than one resistor so as to obtain the bias of said second transistor, and to obtain the negative feedback loop for the amplifier composed of said second and third transistors, and a switching circuit consisting of four diodes connected in the shape of a ring, the arrangement being such that a signal received by the 19 KC tuning coil is multiplied to a 38 KC signal by the frequency multiplying diodes, the resultant 38 KC signal being impressed on the direct-coupled amplifier to obtain 38 KC outputs of opposite polarities from the emitter and collector of the third transistor, and said 38 KC outputs being coupled with a stereophonic signal supplied from the first transistor and then impressed on a pair of connections located at opposite ends of one of the diagonal lines of the switching circuit, whereby separated left and right signals are taken out from opposite ends of another diagonal line of said switching circuit.