Patent US3733441A successfully refreshed from Google Patents.
US3733441A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ambipolar microphone unit
Assignee: MARINE MIDLAND BANK NA A NATIONAL BANKING ASSOCIATION AS AGENT
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Filing: 1971-06-14
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Granted: 1973-05-15
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Expires: 1991-06-14
Abstract
Abstract A microphone unit for incorporation in a telephone headset or the like including a low signal output transducer, and a polarity independent current control amplifier circuit for amplifying the transducer signals and having a pair of substantially identical parallel oppositely connected main current control devices, such as transistors, each having their load terminals arranged for controlling current flowing in a normal forward direction which is opposite to that of the other so that there will always be one fully conductive and one partially conductive or nonconductive path across the microphone unit terminals independently of the polarity of the D.C. current to be modulated by the microphone unit. Drive circuit means energized by the voltage on the telephone lines applied to the microphone unit terminals are provided to receive the transducer signals and amplify the same before being applied to the control terminals of the current control devices regardless of the polarity of the energizing voltage.
Inventors
- 👤 D Mccorkle
- 👤 L Hagey
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 17:45
CPC Classifications
H; H04; H04M; H04M1/00; H04M1/60; H04M1/6008; H04M1/02; H04M1/03
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
330 words
A microphone unit to be connected across a pair of communication lines through which D.C. current flows in either direction, which current is to be modulated by said microphone unit, said microphone unit comprising: a low signal level generating microphone transducer for generating low level electrical signals from sound waves impinging thereon, and an amplifier circuit energizable by D.C. current flowing in either direction through said communication lines and responsive to said transducer signals, said amplifier circuit comprising: a pair of energizing current input terminals to be connected across said pair of communication lines; a pair of main current control devices each having load terminals between which current flows more readily in one direction therethrough and a control terminal for rendering said load terminals readily conductive when driven by a current or Voltage of a given direction or polarity, said load terminals of said main current control devices being connected across said energizing current input terminals so more current will flow through one main current control device when the voltage on the communication lines is of one polarity and more current will flow in the other current control device when the voltage on the communication lines is of the other polarity; and a driver current control device means used in common with said main current control devices and having load terminals between which current flows more readily in one direction therethrough and a control terminal connected to the output of said transducer for varying the current through the latter load terminals in response to said transducer signals; and circuitforming means establishing a circuit with the load terminals of said driver current control device and the control terminals of said main current control devices to form a path for driving the control terminal of the main current control device which has its load terminals connected to a voltage on said input terminals of a polarity to effect conduction between the load terminals in the direction where current flow is a maximum.
Claim 2
Dependent Claim
330 words
A microphone unit to be connected across a pair of communication lines through which D.C. current flows in either direction, which current is to be modulated by said microphone unit, said microphone unit comprising: a low signal level generating microphone transducer for generating low level electrical signals from sound waves impinging thereon, and an amplifier circuit energizable by D.C. current flowing in either direction through said communication lines and responsive to said transducer signals, said amplifier circuit comprising: a pair of energizing current input terminals to be connected across said pair of communication lines; a pair of main current control devices each having load terminals between which current flows more readily in one direction therethrough and a control terminal for rendering said load terminals readily conductive when driven by a current or Voltage of a given direction or polarity, said load terminals of said main current control devices being connected across said energizing current input terminals so more current will flow through one main current control device when the voltage on the communication lines is of one polarity and more current will flow in the other current control device when the voltage on the communication lines is of the other polarity; and a driver current control device means used in common with said main current control devices and having load terminals between which current flows more readily in one direction therethrough and a control terminal connected to the output of said transducer for varying the current through the latter load terminals in response to said transducer signals; and circuitforming means establishing a circuit with the load terminals of said driver current control device and the control terminals of said main current control devices to form a path for driving the control terminal of the main current control device which has its load terminals connected to a voltage on said input terminals of a polarity to effect conduction between the load terminals in the direction where current flow is a maximum.
Claim 3
Dependent Claim
30 words
The microphone unit of claim 1 wherein said main current control devices are junction power transistors of the same type, and said driver current control device is a junction transistor.
Claim 4
Dependent Claim
66 words
The microphone unit of claim 1 wherein said main current control devices are respectively PNP and NPN junction power transistors each having their emitters connected to the same one of said input terminals and their collectors connected to the other input terminal of the microphone unit, the connections between said emitters, collectors and input terminals being free of electrical components having any significant voltage dropping resistance.
Claim 5
Dependent Claim
93 words
The microphone unit of claim 3 wherein the driver current control device means is a transistor whose emitter and collector are coupled between the bases of the power transistors in a direction to carry the emitter to base drive current of the power transistor having its emitter and collector coupled between the input terminal having the proper relative polarity for maximum collector current, whereby the base to collector junction of the other power transistor acts as a steering rectifier to provide circuit continuity to one of the input terminals of the microphone unit.
Claim 6
Dependent Claim
99 words
The microphone unit of claim 4 wherein there is provided a bias voltage developing capacitor, said low signal level generating microphone transducer is connected between the base of said driver transistor and one plate of said capacitor whose other plate is connected to the emitter of the driver transistor, and there is provided a bias voltage coupling resistor connected between the junction of said low signal level generating microphone transducer, and said capacitor and the collector of the driver transistor, whereby a bias voltage is developed across said capacitor which set the proper operating condition of said driver transistor.
Claim 7
Dependent Claim
75 words
The microphone unit of claim 1 wherein said driver current control device means comprises a driver current control device used in common by said main current control devices and having one of its load terminals coupled to the control terminals of both of said main current control devices and the other load terminal coupled to the juncture of a pair of rectifiers which are connected in series in an opposite sense across said input terminals.
Claim 8
Dependent Claim
109 words
The microphone unit of claim 6 wherein there is provided a biasing circuit for said main current control device driver means including a bias voltage developing capacitor coupled in series with said transducer between the control terminals and the other load terminal of said current control driver device coupled to said rectifiers, the plate of said capacitor nearest the control terminal of said current control drive device being coupled through separate voltage isoLating elements to said input terminals wherein said capacitor is charged to the same voltage through one of said rectifiers and the non-corresponding voltage isolating element independently of the polarity of the voltage on said input terminals.
Claim 9
Dependent Claim
16 words
The microphone unit of claim 7 wherein each of said current control devices is a transistor.
Claim 10
Dependent Claim
37 words
The microphone unit of claim 1 wherein the connection of said load terminals of said main current control devices to said input terminals is a direct connection free of eletrical components having any significant voltage dropping resistance.
Claim 11
Dependent Claim
38 words
The microphone unit of claim 1 further including a biasing voltage circuit for said current control device driver means connected across said input terminals and coupled to the control terminal means of said driver current control device means.
Claim 12
Dependent Claim
39 words
The microphone unit of claim 1 sized and shaped to be mounted within the mouthpiece portion of a telephone handset for connection to the terminating ends of a pair of communication lines to be connected to said input terminals.
Claim 13
Dependent Claim
39 words
The microphone unit of claim 3 sized and shaped to be mounted within the mouthpiece portion of a telephone handset for connection to the terminating ends of a pair of communication lines to be connected to said input terminals.
Claim 14
Dependent Claim
308 words
A telephone handset having a mouthpiece housing, a microphone unit mounted within said mouthpiece housing, said microphone unit including: a microphone transducer in the front of said mouthpiece housing for generating a low signal level voltage; a printed circuit board assembly mounted behind said transducer and forming a polarity insensitive amplifier circuit, said printed circuit board assembly having energizing current input terminals for connection to a pair of telephone communication lines and including a pair of main current control devices each having load terminals between which current flows more readily in one direction therethrough and a control terminal for rendering said load terminals readily conductive when driven by a current or voltage of a given direction or polarity, said load terminals of said main current control devices being connected across said energizing current input terminals so more current will flow through one main current control device when the voltage on the communication lines is of one polarity and more current will flow in the other current control device when the voltage on the telephone lines is of the other polarity, a driver current control device used in common with said main current control devices and having load terminals between which current flow more readily in one direction therethrough, and a control terminal means connected to the output of said transducer for varying the current through the latter load terminals in response to said transducer signals, and circuit-forming means establishing a circuit with the load terminals of said driver current control device and the control terminals of said main current control devices to form a path for driving the control terminal of the main current control device which has its load terminals connected to a voltage on said input terminals of a polarity to effect conduction between the load terminals in the direction where current flow is a maximum.
Claim 15
Dependent Claim
308 words
A telephone handset having a mouthpiece housing, a microphone unit mounted within said mouthpiece housing, said microphone unit including: a microphone transducer in the front of said mouthpiece housing for generating a low signal level voltage; a printed circuit board assembly mounted behind said transducer and forming a polarity insensitive amplifier circuit, said printed circuit board assembly having energizing current input terminals for connection to a pair of telephone communication lines and including a pair of main current control devices each having load terminals between which current flows more readily in one direction therethrough and a control terminal for rendering said load terminals readily conductive when driven by a current or voltage of a given direction or polarity, said load terminals of said main current control devices being connected across said energizing current input terminals so more current will flow through one main current control device when the voltage on the communication lines is of one polarity and more current will flow in the other current control device when the voltage on the telephone lines is of the other polarity, a driver current control device used in common with said main current control devices and having load terminals between which current flow more readily in one direction therethrough, and a control terminal means connected to the output of said transducer for varying the current through the latter load terminals in response to said transducer signals, and circuit-forming means establishing a circuit with the load terminals of said driver current control device and the control terminals of said main current control devices to form a path for driving the control terminal of the main current control device which has its load terminals connected to a voltage on said input terminals of a polarity to effect conduction between the load terminals in the direction where current flow is a maximum.
Claim 16
Dependent Claim
97 words
The telephone handset of claim 13 wherein said microphone transducer is a background noise eliminating microphone having a movable diaphragm mounted at its periphery to a microphone support frame, said support frame having apertures formed therein to allow remotely generated sound waves to enter the support frame and reach the rear of said diaphragm to the same extent as such sound waves are present at the front of said diaphragm to cancel the effects of such remotely generated sound waves, sound waves coming substantially immediately from the front of said microphone being effective to move said diaphragm.
Claim 17
Dependent Claim
58 words
The telephone handset of claim 13 wherein said driver current control device has one of its load terminals coupled to the control terminals of both of said main current control devices and the other load terminal coupled to the junctures of a pair of rectifiers which are connected in series in an opposite sense across said input terminals.
Claim 18
Dependent Claim
66 words
The telephone handset of claim 13 wherein said main current control devices are respectively PNP and NPN junction power transistors each having their emitters connected to the same one of said input terminals and their collectors connected to the other input terminal of the microphone unit, the connections between said emitters, collectors and input terminals being free of electrical components having any significant voltage dropping resistance.
References Cited (Backward Citations)
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US3300585A
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US3378649A
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-05-14 | 1976-11-13 | 1977-05-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-05-14 | 1980-11-13 | 1981-05-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-05-14 | 1984-11-13 | 1985-05-15 | $7700.00 | Window Closed / Lapsed |