ELECTROENCEPHALOPHONE AND FEEDBACK SYSTEM

• US 3,753,433 A
• Filed: 01/18/1971
• Issued: 08/21/1973
• Est. Priority Date: 01/18/1971
• Status: Expired due to Term

• Current Assignee: Frank Bakerich, Robert T. Scully
• Original Assignee: Frank Bakerich, Robert T. Scully
• Inventors: Bakerich, Frank, Scully, Robert T.
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US05/107,215
• Time in Patent Office: 946 Days
• Field of Search: 128/2.1A,2.1B,2.1R,2.6R,1C,422
• US Class Current: 600/545
• CPC Class Codes: A61B 5/301 providing electrical separation, e.g. by using isolating transformers or optocouplers
• CPC Class Codes: A61B 5/332 Portable devices specially adapted therefor
• CPC Class Codes: A61B 5/369 Electroencephalography [EEG] devices for psychotechnics A61B5/16
• CPC Class Codes: A61B 5/374 Detecting the frequency distribution of signals, e.g. detecting delta, theta, alpha, beta or gamma waves
• CPC Class Codes: A61B 5/7415 Sound rendering of measured values, e.g. by pitch or volume variation A61B5/741 takes precedence

Abstract

An electroencephalophone which is battery operated and completely self-contained in a headset to be worn by the user and having a plurality of scalp electrodes carried on flexible leads permitting placement of the electrodes on the user'"'"''"'"'s head when the headset is mounted thereon and having an electronic circuit and transducer for converting brain wave signals picked up by the electrodes into recognizable audio tones enabling the user to listen to his own brain wave generation. The scalp electrode signals are amplified and chopped by an audible oscillator signal the frequency of which is controlled by the scalp electrode signals. The resulting combined amplitude and frequency modulation of the audible generator tone provides a distinctive sound for brain wave recognition.

Claims

1. An electroencephalophone feedback system comprising:

scalp electrodes;

an amplifier having an input connected to said electrodes and having an output;

an output circuit connected to said amplifier output and including a voltage actuated chopper device and a series load impedance connected thereto;

a transducer connected to said load impedance;

a relaxation oscillator generating an audible frequency connected to and driving said chopper device, said oscillator having a timing capacitor controlling its said frequency; and

means connected to said amplifier output and capacitor for charging said capacitor at a rate dependent upon the potential at said amplifier output.

2. A system as defined in claim 1:

a voltage supply and common;

said oscillator comprising a uni-junction transistor having its emitter connected to said capacitor and its bases connected to said voltage supply and common to fire when its emitter is raised to a predetermined voltage, said means being connected to said emitter to periodically raise the voltage thereat to said predetermined value.

3. A system as defined in claim 2, said means comprising a field effect transistor connected to said output, emitter, capacitor and voltage supply.

4. A system as defined in claim 3, said field effect transistor having its drain terminal connected to said output, its gate terminal connected to said voltage supply and its source terminal connected to said emitter and capacitor.

5. A system as defined in claim 2;

an impedance connected in series in the connection between common and said uni-junction base connected to common; and

output terminals connected to said impedance for providing a frequency modulated brain wave signal.

6. A system as defined in claim 1 and having a common, and said chopper device comprIsing a bipolar transistor having its emitter connected to said common, its base connected to said oscillator, and its collector connected through said load impedance to said output.

7. A system as defined in claim 1 wherein said transducer is connected across said load impedance;

and a pair of parallel reversely connected diodes connected in series with said transducer and impedance.

8. A system as defined in claim 1, and manually controlled means for adjusting the magnitude of said output potential thereby setting the range of amplitude and frequency modulation.

9. A system as defined in claim 8 said transducer being connected across said load impedance;

and a pair of parallel reversely connected diodes connected in series with said transducer and impedance providing a squelch action below a predetermined signal level, said signal level being controlled by said manually controlled means.

10. A system as defined in claim 1, said amplifier comprising a narrow band-pass amplifier having peak sensitivity in the range of about 4 to 13 cycles per second and a sharp roll-off outside of said range.

11. A system as defined in claim 10, said amplifier comprising a dual operational amplifier.

12. A system as defined in claim 1, said amplifier having an input impedance substantially higher than the scalp contact resistance of said electrodes to minimize generation of artifactual signals.

13. A system as defined in claim 12 wherein said amplifier comprises a pair of source follower field effect transistor pre-amplifiers connected to said electrodes;

and a dual operational amplifier having a balanced input connected to the outputs of said pre-amplifiers.

14. A system as defined in claim 13 wherein said operational amplifier has common mode rejection thereby eliminating common mode noise originating at said electrodes and the requirement for system operation in a shielded room.

15. A self-contained electroencephalophone comprising:

a headset having an earphone housing and a headband connected thereto for mounting on the head of a user;

a plurality of scalp electrodes adapted for mounting on the user'"'"''"'"'s head to provide an electric signal pickup of brain waves;

flexible leads carried by said housing and connected to said electrodes for permitting placement of the latter on the user'"'"''"'"'s head when the housing is mounted thereon; and

an electronic circuit carried by said housing and comprising an amplifier having an input connected to said electrodes and having an output;

an output circuit connected to said amplifier output and including a voltage actuated chopper device and a series load impedance connected thereto;

an oscillator generating an audible frequency connected to and driving said chopper device; and

means connected to said amplifier output and said oscillator for controlling said oscillator frequency as a function of the potential at said amplifier output; and

a transducer carried by said housing and connected to said load impedance.

16. An electroencephalophone as defined in claim 15, carried by said housing said electronic circuit including a voltage supply and common;

said oscillator having a timing capacitor controlling its frequency and comprising a uni-junction transistor having its emitter connected to said capacitor and its bases connected to said voltage supply and common to fire when its emitter is raised to a predetermined voltage; and

said means comprising a field effect transistor having its drain terminal connected to said amplifier output, its gate terminal connected to said voltage supply and its source terminal connected to said emitter and capacitor.

17. An electroencephalophone as defined in claim 16:

said chopper device comprising a bipolar transistor having its emitter connected to said common, its base connected to said oscillator, and its collector connected through said load impedance to said output.

18. An electroencephalophone as defined in claim 17, anD a pair of parallel reversely connected diodes carried by said housing connected in series with said transducer and impedance.

19. An electroencephalophone as defined in claim 15;

a resistor connected to said output;

an EEG output terminal;

a voltage supply carried by said housing;

a transistor having its base connected to said resistor, its collector connected to said voltage supply, and its emitter connected to said terminal;

a light source connected to said terminal; and

a light detector electrically insulated from said headset and optically coupled to said light source for providing an electrical brain wave signal.