US1633186A - Arrangement for converting acoustic energy into electrical energy - Google Patents

Description

June 21 1927 A. MEI5$NER1-:-

ARRANGEMENT FOR CONVERTING ACOUSTIC ENERGY INTO ELECTRICAL ENERGY Filed May 29, 1924 lNVENTOR ALEXANDER MHSSN ER 59 &%

ATTORNEY Patented June 21; 1 927.

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Application filed Kay 29, 1e24, Serial n.

My inventionrelates to arrangements for converting acoustic energy into electrical energy by meansof piezo-electric crystals.

An ob ect of the invention is to provide a device which will convert sound wavesinto electric waves without distortion. v p

Another object is to provide an arrangement whereby the individuabefi'ectsof sepa rate sources of sound'may be combined to operate any sound receiving device,'the relative intensities of the separate sources being separately controlled in their effects on the sound receiving device.

Other objects will be app rent fronr the following description and claims when considered with the accompanying drawing, in which: Y

Fig. 1 shows a circuit embodying. one form of my invention.

Fig. 2 shows a circuit embodying a modification; I

The so-called piezo-electric crystals have, as known, the property of reacting upon mechanical shocks by freeing electric charges and thereby generating an (M. F.

According to the" present invention this phenomenon is used in such-a way that when the crystal is fastened to a sound-board of a musical instrument, the charges becoming ,free in the rhythm of the acoustic vibrations are directly led to the input (grid-cathode) of an incandescent cathode tube. The platefilament current of this vacuum tube then fluctuates in the same sense as the grid volta c. This arrangement represents a means 0 converting acoustic energy into electrical energy. A great advantage of this or stal-- microphoneas compared with the usua carbon microphone is that the sounds are re produced without distortion. Fig. 1 of the annexed drawing shows an exam le ofthe new arrangements is a sound board, for instance of a violin. K- is the crystal .provided'with two metal coatings, V is an amplifying vacuum tube WhlCll, for instance, contains the primary of a transformer C in the plate-filament circuit. Connected to the secondary of transformer C is telephone T. p p

In order to reproduce orchestral music, one or more crystals may be fastened to the different musical instruments and the separate amplifications can be regulated iii 1 3. and; In, scra -y m 2 1925.

a waythat themusic is correctly reproduced. A clrcult for accomplishing this result'is illustrated in. Fig. 2. R B R and R are v the sound boards or sound responsive 'portions of the different musical instruments. Mounted on each of the sound boards'B R R isa crystal K K and K respectively.

In order to increase the effect of one sound board, several crystals may be fastened to the same sound board. Sound board R has two crystals K', and'K fastened to it.

Eac nected to'the-inpu't circuit of aseparate' am. pl1fiei tube V V V,, -,V and V .respectively and the output of each ofthese tubes;

connected'to the 'rimary of a separat'e'transformer' C (3,, C and (3 respectively, Thesecondaries, of: these transformers are connected in series with a telepholie T, so that their joint effects will be impressed-on the telephone T. Care should 'be'taken that the transformers are connectedfso that or sta'ls K and K mounted on the add in their effects. If instead of the sound board a suitable membrane is used, tliis arrangement canbe employed for the same microphone is taken. 4

Having described my invention, what I claim is:

1. A device for converting sound waves into electricalv impulse undulations, which comprlses a plurality of piezo-electric bodies purposes as ordinary crystal K K K,,,'K,, and K isfcon? 7 same sound card adapted to produce electrical impulse undu- 5 latio'ns, in accordance-with the variation in: pressure exerted thereon, means associated f with certain of said bodies adapted to produce ,YfllllltlODS in pressure on certain of said bodles in; response to sound waves, means associated with certain others of the said piezo-electr'ic bodies adapted to produce vw r'iations in,p'ressureon said last mentioned bodies, am jlifyin means associated with said lezo-e ectricio v der t e'se arate outputs of the several amfilifiers a itive."

2. A device for converting sound'fwaves;

into electrical undulations comprising in combination, a luralit ments; a; piezo-e ectric ody associated with each of said instruments and be a d to generate electrical undulations inaccorddies, and meansto re'nof musical .instru- 5 ance with the output of said instruments,

separate amplifying means connected to each of said piezoectric bodies, and a reproducer adapted tobe actuated by said, ampli struments adapted to produce mechanical vibrations, a

iezo-electric body connected to each of said instruments and adapted to be vibrated by said mechanical vibrations and being also adapted to generate electrical undulations in accordance with the vibrations of the piezo-electric bodies, means to amplify said electrical undulations and means to combine said amplified undulations.

4. In a device for converting acoustical impulses into electrical undulations the combination, of a musical instrument adapted to produce mechanical vibrations, a plurality of piezo-electric bodies connected to said instrument and adapted to be vibrated by the vibrations of said instrument, to produce electrical undulations connected to a separate amplifier each of said bodies adapted to amplify the electrical undulations produced thereby, and means whereby said amplified impulses may be added together.

5. In a devicelfor converting acoustical impulses into electrical undu1ations,'the combination of a sound producing member having a vibratorye'lement, a plurality of piezoelectric bodies connected to said element and adapted to be vibrated by said element to produce electrical undulations, a separate amplifier connected With each of said bodies, adapted to amplify said electrical undulations and means whereby said amplifiedundulations may be added together.

6. A device for converting sound waves into electrical undulations comprising in combination, a plurality of sound producing members each having a vibratoryele ment, a piezo electric body associated with each of said elements and being adapted to generate electrical undulations in accordance with the vibration of said elements, separate amplifying means connected to each of said piezo-electric bodies, and a reproducer adapted to be actuated by said amplifiers.

ALEXANDER MEISSNER.

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