US2066133A

US2066133A - Wave translating device

Info

Publication number: US2066133A
Application number: US668335A
Authority: US
Inventors: Alexander I Abrahams
Original assignee: Individual
Current assignee: Individual
Priority date: 1933-04-28
Filing date: 1933-04-28
Publication date: 1936-12-29
Anticipated expiration: 1953-12-29

Description

Dec. 29, 1936. A. l. ABRAHAMS 2,066,133 4 4 WAVE TRANSLATING' DEVICE Filed April 28, 1933 1 5- F a. E a6 23 it 2% L 22 I I [T 4- 14 i4 k 22 21 ml 16 5 5? 1:

I v v INVENTOR v 1 v j Alzxanderz' qb .BY I.

ATTORNEY Patented Dec. 29, 1936 UNITED ES "PATENT OFFICE.

WAVE TRANSLATING DEVICE Alexander I. Abrahams, New York, N. Y.

Application April 28, 1933, Serial No. 668,335

6 Claims. (01. 1i9 138) v This invention relates to wave translating devices, and with particularity to a device for translating sound waves into electric waves and vice versa.

The invention has for its principal object to provide an improved form of wave translating device employing a ribbon like vibratory translating element.

A feature of the invention relates to an improved type of microphone.

A further feature relates to an improved form of wave vibratory element suitable for use in wave translating devices such as microphones, reproducers or the like.

A still further feature relates to the novel organization, arrangement and relative location of parts which go to make upa simple and highly efficient wave translating device.

Other features and advantages not specifically enumerated will be apparent after a consideration of the following detail descriptions and the appended claims.

Referring to the drawing,

Fig. 1 is a front view of a device according to the invention;

Fig. 2 is a right hand elevational view, partly I in section of the device of Fig. 1;

Fig. 3 is a partial top plan View of the device of Fig. 1 with the cover and housing removed;

Fig. 4 is a partial sectional view of Fig. 2 taken along the line 4--4 thereof Y Fig; 5 is a sectional view of Fig. 3 taken along the line 5-5 thereof; and

-Figs. 6 and '7 show modified formed in the vibratory member.

Referring more particularly to the drawing there is shown a rectangular frame member I having

flanges

2 and 3. Each of the

flanges

2 and 3 is provided with a recess 4 to receive an insulating strip 5. The-strips 5 are attached to the

flanges

2 and 3 by suitable screws 6. Mounted on each of the insulator strips 5 is a metallic strip 1 which is fastened thereto by means of screws 8. The metallic strips I serve to clamp the ends of the vibratory member 9 against the associated insulator members 5. As shown in the drawing, the member 9 is preferably in the form of a metallic ribbon of thin material such as aluminum, dur-alumin or the like. In order to stiffen the member 9 longitudinally to enable it to vibrate in a piston like manner the said strip is provided with a longitudinal embossed rib I 0. To further facilitate the vibration of the member 9 in a piston like manner the ends of said member may be provided with transverse embossings H. While the drawing shows the member I0 consisting of a single recess, it will be understood that the invention contemplates the provision of a series of separate longitudinal recesses as desired. It is of course apparent that forms of ribs the rib I!) need not be straight but can have other configurations as shown at H] and Win Figs. 6 and 7. Similarly, while the drawing shows a single transverse recess, at each end of the ribbon member, it will be understood that a plurality of these ribs may be provided at each end to increase the flexibility of the said member, as shown in Fig. 6. In addition the transverse ribs whether used singly or in multiple may extend to the edges of member 9 as shown in Figs. 6 and '7 at H It will also be understood that other'well known expedients for rendering the ends of the ribbon flexible may be employed. If desired the member 9 may have its opposite ends clamped be; tween the

members

5 and 1, so as to maintain the said member 9 ma state of tension, although this is not absolutely necessary so long as the said member 9 is actively moving throughout the greater portion of its length'in a piston like manner, that is with its substantial entire area moving uniformly for a given unit of force impressed thereon. For the purpose of conducting current through the member 9 there is provided a lead-in wire l2 which is fastened by means of screw 8 and therefore contacts with the lower end of the member 9. Another lead-in wirel3 connects with the upper end of the member 9. By means of these wires I2 and I3 therefore external connections can be made to the ribbon member 9. p

Attached to the front face of the member l are a pair of ple pieces l4, I5. As shown more clearly in Figs. 2 and 4 these pole pieces arein the form of flat meta-l members of iron or other magnetic material, and are held in place by means of screws 16 soas' to define a longitudinal magnetic gap between their opposed edges, in which gap is situated the member 9. It'will be understood of course that the member] I carrying, the pole pieces l4 and I5 is of non-magnetic material such as aluminum or the like. 7

As will be apparent from the drawing the gap defined by the pole pieces is slightly wider than the widt'h of the member 9 so as to enablethe said member 9 to vibrate without contacting with the surface of the poles. Situated in the rear of the member 9 is a rigidstrip ll of non-magnetic material such as brass or the like. The strip i1 is carried by a pair of screws l8 and I9 which are threaded into the flange portions 2 of the member I. By means of the screws [8 therely in Fig. 4. The magnets and 2| may be held firmly in position by means of screws 22 passing through the wall of the member I. Preferably,

although not necessarily, the space defined by the U-shaped magnets is provided with a filling of a non-resonant material such as cotton, wool or the like, as indicated by the numeral 23. As

Will be apparent from Fig. 4, the damping plate I1 is of slightly less Width than the member 9 so as to allow egress of air from theback of the member 9 into the space defined by the magnets. However, because of the filling material 23 the air in this space is prevented from resonating at any frequency within the useful range of the device.

For the purpose of enclosing the above as- V sembly there isprovided acylindrical cup shaped .spondingly threaded cap member 26.

out its effective length.

housing 24 of metal or other suitable material having a threaded flange 25 to receive a corre- The cap member 26 is provided with a series of four locks Zlwhich engage the respective corners 28 of the member I to clamp the above described assembly firmly in position between the cap and the flange 25. If desired theannular opening in the cap as a microphone the sounds or other waves to be translated into corresponding currerits'impinge upon the member 9, causing it to vibratethrough- Sincethis member is situated in an intense and concentrated magnetic field defined by the pole pieces l4 and I5,

there are enerated currents corresponding to the Waves affecting the member 9. These cur- 'rents may be taken off by means of the lead wires l2 and I3 and connected to suitable amplifying and/or current transmitting devices. On

the other hand, when the device is to be used as a sound reproducer the soundcurrents are applied to the lead-wires I2 and I3 causing corresponding electric fields to beset ;up in and around the member 9, and resulting incorresponding vibrations of this member.

It has'been found that by means of the'damping plate H the response of the device may be varied as desired. For example the elastic restoring force of the vibratory system is a function 'ofthe'area of the member l1 and its spacing relative tothe member 9. Secondly, by varying this latter spacing theinherent restoring force of the system, and consequently the resistance thereof may be accurately varied.

It will be understood of course that the invention is not limited to the use of this air damping to control the response of the device. For example, the member 9 may be subjected to any desired tension so as to control its actual period of vibration. However, as above described preferably the member 9 is designed and maintained so as to vibrate in a substantially piston like manner. The restoring forces or elasticity of the vibrating system being substantially entirely provided by the air space between the member 9 and the member ll. It is to be noted that since the member i! isof less width than the vibratory 'member 9 the impinging sound waves strike the latter member directly, and thereis no reflection response in any portion of the useful range of the device.

It will be understood that various changes and modifications may be made herein without departingfrom the spirit and. scope of the invention,.and while particular materials have been specified the inventionis not limited thereto. For example, the member 9 may be treated or formed to impart to it the necessary or required elasticity and/orrigidity. Likewise, this member instead of being made in the form of a continuous strip maybe perforated or otherwise formed to control its actual period of vibration. Likewise, the packing strip I1 may be formed or perforated to control the responseof the device, and if desired the member I! may be adjusted not only to vary the distance between it andthe it and the pole pieces I4 and l5.

. It will be understood of course that instead of employing permanent magnets for magnetically energizing the device, any well known form of;

and a backing plate mounted in spaced relation 4. A device of the character described comprising a pair of pole pieces defining a magnetic gap in the form of a rectangularslit, a rectangular strip of conductive, material mounted in 7 said gap with the edges of the strip in spaced I relation to the opposing edges of said pole pieces, a. backing strip, and means for adjusting the spacing between said ribbon member and said backing strip. I

5. A device according to claim 4 in which the backing strip is substantially co-extensive in length with the ribbon member, butis of. lesser width to provide deferent passages for the air in back of said ribbon member. I

6. In a device of the character described the diaphragm, a damping plate mounted in spaced relation to said diaphragm and to said pole pieces, and means for avoiding undesired resonance in the air space in back of said diaphragm and damping plate.

ALEXANDER I. ABRAHAMS.