US2157720A - Microphone - Google Patents

Description

May 9, 1939.

E. SEVERIN MICROPHONE 4 Filed Aug. 4, 1954 INVENTOR SEVERIN ATTORNEY aten'ted May 9, 1939 NITED STATES "PATENT OFFICE 2,157,720 MICROPHONE Edwin Severin, Berlin, Germany, assignor to Teleiunken Gesellschaft fiir Drahtlose Telegraphic m. b. 11., Berlin, Germany, a corporation of Germany Application August 4, 1934, Serial No. 738,460 In Germany August 26, 19 33 6 Claims.

5 stance, of airplane cabins, engine rooms, or the like, it is a general custom to use the so-called laryngophone for electric voice transmission, particularly in radio intelligence transmission. However, the rendition of the voice is rather faulty inasmuch as sibilants and explosive articulations, which are essential for proper'intelligibleness, are not picked up by the larynx type of microphone. Also with the cheek-type of microphone it is impossible to obtain a favorable pick- 5 -up of articuled sounds for the reason that the sound is subject to great damping by the flesh of the cheek so that the diaphragm of the microphoneis no longer excited suflicientlyi This is particularly ..d.isadvantageous in regard to the 2 high-frequencies whose acoustic energy is inherently low anyway.

Acoustic pick-up devices of this kind are preferably carbon microphones capable of a relatively high voltage provided that the natural 25 period of the diaphragm has been chosen sufli- 0 of the diaphragm are practically not transmitted at all by the microphone.

Microphones in which the oscillatory dia phragmconstitutespart of a magnetic circuit, sim-' ilarly as in headsets, possess only -a narrow frequency band so that sibilants are rendered by them only improperly.

' Microphones of this kind are-acoustic pick-ups which are sensitive or responsive to direct. airpressure variations so that they will easily respond to these. Indeed, the diaphragms are excited not only by the sound waves emanating from a person talking to the microphone, but also by waves arising at more or less great proximity so that they will be caused to oscillate also by 45 these vibrations. In other words, acoustic stray noises will be included in the transmission and thus impair the reproduction to a considerable extent inasmuchas the stray noise level lies considerably above the voice level.

50 Now, according to this invention these draw- 55 positive mechanical actions, is fitted on top of an oscillable structure or system. Magneto-electric systems offer this advantage over the electrostatic ones that it is easier to establish a connection between the oscillating part of the system and the 60 coupling links. The vibrating masses of the system as well as their surface are so small and are so shaped that, with suitable arrangement they can practically not be set in motion by direct airpressure. This diaphragmless system will thus not respond to acoustic disturbing noises so that these latter will be kept out of the transmission.

Such a system together with a suitable coupling link is fitted on top of the skull at a point which is set in movement by the vibrations the frequency and amplitude distribution of which corresponds as closely as feasible to the acoustic voice. Inasmuch as the source or seat of sibilants and of explosive sounds is in the neighborhood of the upper jaw (incisors, palate), preferably a place is chosen in the vicinity of the upper jaw at which the bone is covered only by a thin and therefore but slightly damping or sound-deadening skin. Excellent pick-up points are the nasal bone, the cheek bone, the forehead and the teeth. When speaking the sound waves are transmitted by virtue of bone conduction through the coupling means to the oscillatory system. The transmissible frequency band of such microphones,- especially within the higher frequency ranges, is essentially enlarged in contrast with other microphone constructions.

In the drawing a .number of embodiments of the basic idea of the invention are illustrated. Fig. 1 shows in two views the microphone l,

which in this instance is strapped by ribbons 2 onto the head 3. The microphone is furnished with a permanent magnet 4 upon which the poleshoes 5 and 6 are fitted. In the air-gaps I, between the pole-shoes, the keeper 9 oscillates about the pivot 8, the said keeper 9 being surrounded by a coil Ill. The voltages induced in the coil by the movements of the keeper are fed to an amplifier. Attached to the keeper 9 is'the coupling means or link i i which is likewise pivotable about 8. At its free ends it has a suitably formed or molded piece I2, the latter being fitted upon the nasal bone or bridge of the nose. When speaking, the sound waves are transmitted by virtue of bone conduction nothat the bone of the nose experiences vibrations which are transmitted to the molded piece 12. The result is that the keeper or armature 9 is caused to move through the intermediary of the coupling links. Instead of two coupling-links ll, only one may suffice. The microphone i is enveloped by the case i3.

In Figs. 2, 3, 4, and 6 parts are shown which are designated by the same reference numerals as in Fig. 1.

Referring more especially to Fig. 2, the coupling link ii is shown arranged with the same magnetic field disposition as in Fig. 1, except that in Figure 1 the link H is fastened on the outside of easing l3 to the pivot point, whereas in Figure 2 the upper portion of the coupling'link ll forms the armature.

In the case of Fig. 3, with a magnetic system comprising the permanent magnet 4, pole-shoes in the magnetic shunt IS. The coupling link ll with the molded or fashioned piece l2 engages the keeper 9 directly outside the pivot thereof.

Fig. 4 shows another embodiment of the electromagnetic oscillation system in which the keeper 9 inside the two pole-shoes 5 and 6 is pivoted about the axis 8. At the axis 8 engages the coupling link with the molded piece i2.

By virtue of the movements of the keeper, also in the embodiment shown'in Figs. 2-4, voltages are induced. The oscillation system could consist also of a system furnished with a keeper oscillating anteriorly of the poles.

Fig {5 shows an oscillatory system predicated upon the dynamic principle. The magnetic field is excited by the permanent magnet I! with which are associated the additional iron paths I8 and -l 9. These form the annular air-gap 20 in which the winding 2i oi the movable coil is able to move.

The latter is guided, in turn, by the fixed coil former 22 and the movable coil centering means 23.. At the centering means movable coil 2i engages the coupling link 24 with the former or molded piece 25 which is generally similar to member I2 mentioned above except for the omission of the coupling link ll.

The molded pieces in these embodiments could also be given other suitable shapes than that to be applied to the nose, the latter to be chosen in accordance with'the pick-up point. For example, one may substitute for the nose attachment another shaped molded piece for attaching to or application'for another shaped piece for attaching to the cheek bones.

An embodiment of the object of this invention for picking up the sound on the teeth is shown in Fig. 6. The oscillation system 26 could be of a kind as hereinbefore illustrated rather than the one here shown. The system is encased-by I3, the latter having a tubular attachment or ex-. tension 21 in which the coupling link i I with the shaped or molded piece l2 moves. The latter projects through the opening 28 in the extension 21. Contacting between keeper 9 and the poleshoes 5 and 6 is prevented by the rubber buirers 29 which at the same time insure proper. dampa smokers pipe between the teeth.

I claim: 4 1. A microphone especially adapted for the transmission of voice subjected to acoustical disturbances comprising a casing containing a per manent magnet and an electro-magnet located.

within the field of said permanent magnet, an armature. arranged within said electro-magnet, said armature having a pivot within and passing through the walls of said casing to provide an oscillating part which acts as a pickup point, said pivot being secured to a pair of links connected with a fashioned piece which adapts ,itself to contact with the bone structure of the human body, saidppair of links located on each side of said casing and joined together at a junction point adjacent said fashioned piece.

2. A microphone especially adapted for the transmission of voice subjected to acoustical disturbances comprising an oblong casing having a tubular extension member, said casing containing a permanent magnet and an electro-magnet within the field of said permanent magnet, an armature arranged within said electro-magnet, a coupling link secured to said armature and located within said tubular extension member, said armature having a pivot within said casing to provide 'an oscillating part which acts as a pickup point, said pickup point consisting of a fashioned piece which adapts itself to contact with the teeth of the human body.

3. A microphone especially adapted for the transmission of voice subjected to acoustical disturbances comprising a casing containing a permanent magnet and an electro-magnet located within the field of said permanent magnet, an armature arranged within said electro-magnet, said armature having a pivot within and passing through the walls of said casing to provide an oscillating part which acts as a pickup point, said pivot being secured outside of said casing to a pair of links joined together at its free end with a fashioned piece which adapts itself to contact armature being connected to a movable shaft acting as a pivot within said casing passing through the walls of said casing, and an outside linkage system connected outside of said casing to the ends of said movable shaft, the free ends joined together at a junction point and joining a fashioned piece which is in contact with the bone structure of the human nose.

5. A microphone especially adapted for the transmission of voice subjected to acoustical disturbances comprising an oblong casing containing a permanent magnet and an electro-magnet located within the field of said permanent magnet, means for retaining said microphone to the head of the human body, an armature arranged within said electro-magnet, said armature being connected to a movable shaft acting as a pivot within said casing and passing through both walls of said casing to provide an oscillating part which acts as a pickup point, said pivotibeing secured to a pair of coupling link members connected with a fashioned piece which adjusts itself to contact the cheek bone of the human body, said pair of links located on each side of said casing and joined together at a iunctionpoint adjacent said fashioned piece.

6. A microphone especially adapted for the transmission of voice subjected to acoustical disturbances comprising a casing, a permanent magnet and an electro-magnet located within the field of said permanent magnet, an armature located within said electro-magnet, said armature being connected to a movable shaft acting as a pivot located within said casing and passing through both walls of said casing to provide an oscillating part which acts as a pickup point, a pair of links being connected outside of the casing to the ends of said movable shaft, the lower end of said links being connected with a fashioned piece which adapts itself to contact with the human skull, said pair of links located on each side of said casing and joined together at a junction point adjacent said fashioned piece.

EDWIN SEVERIN.

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