US2235505A - Microphone support - Google Patents

Description

` B. vF. RYAN MICROPHONE SUPPORT -Filed 0cm 5, 1938 Mach 1s, 1941.

Patented Mar. 18, 1941 PATENT OFFICE IVIICRO'PHONE SUPPORT Byron F. Ryan, L'os Angeles, Calif., assigner to Warner Brothers Pictures, Inc., a corporation of Delaware Application October 3, 1938, Serial No. 232,989

4 Claims.

'This invention relates to sound-wave detecting apparatus such as microphones and parti-cularly to a mounting for such apparatus. This mounting has been designed for use on the end of .a boom used on motion picture sets wherein the microphone is suspend-ed above, or proximate to, the source of sound and moved by the boom to follow ythe sound source.

In the use of a sensitive microphone o-n the end of a boom it becomes a problem to prevent extraneous sounds, caused by the vmovement of the microphone, from being detected and Itransmitted to the sound record. Generally, the boom ann is quite long and flexible, and vibrations are sometimes introduced therein broth vertically and horizontally, caused by movement of the boom or microphone at the end thereof.

.The mounting is in the form of a mechanical lter which is adjustable so that it may be tuned to eliminate certain frequencies, and is of a .shape so as not to interfere with proper functioning of .the microphone. The mount is a `combination filter system which eliminates both high and low frequencies.-

An object ofthe present invention, therefore, is to minimize the effects of moving a boom with a microphone .suspended .thereon during the sound pick-up operation.

Another object of the invention is to mount a microphone so that it may be .spatially adjusted without its being electrical-1y affected.

A fur-ther object of the invention is to provide a mechanical filter mounting for eliminating mechanical vibrations .of different frequencies introduced by movement of the microphone.

A YfurtherA .object of the invention is to enable a mechanical lter mounting to be tuned -fior different loads.

Although the novel features which are believed to be characteristic of this invention are pointed out with particularity in the claims appended herewith, the manner of its organization and the mode of its operation will be better understood by referring .to the following description read in conjunction with the accompanying drawing forming a part thereof, in which Figur-e 1 is .a partial cross-sectional View of the microphone mounting as attached to Ia microphone boom;

Figure 2 is a cross-sectional view of t-he low frequency filter portion of the mounting taken Ialong the 'line 2-2 of Fig. 1; and

Figure 3 is a plan view of the high frequency portion of .the filter mounting .taken along the line 3-3 of Fig. 1.

Referring now to the drawing, in which the same numerals indicate identical element-s, the end `5 of a microphone boom has connected thereto, by .an 'adjustable coupling 6, a rod 'I having -a flanged lower endi 8. The element 5 may be .the extendible end oi the adjustable {crossarm of the boom shown in W. A. Mueller Patent 2,122,778 of July.5, 1938. Rotatably mounted on the rod 'I is a cap or ycover lll having la groot/ed 'or pulley portion I.I, .around which is a cable `I3, one end of which is attached in an eye-bolt I5 on the portion I'I. Fastened tothe upper side of the pulley section by screws I6 isa cylindrical housing IB to which is also fastened one end of a coil spring I9 at point 20. The other end of the coil spring I9 is attached to a collar 2`2 at 23, .the collar 22 being pinned to the rod I by a vpin 24. This arrangement permits the cover .,IIl .to be rotated in one direction about the rod 'I when the cable I3 is pulled, and to be rotated in the other direction by the tension of spring I9 when .the cab-le I3 is released. This mechanism permits 'the rotation of the microphone by the boom operator.

Attached to .the cover` Ill by screws 26 is a conical-shaped shell 2l in which are elongated slots 28, `the purpose of which will be explained. hereinafter. Within the shell 2l is a fine-grained sponged .rubber conforming to the shape :of the shell and made up of .two `sections. 30 and 3|. C

Section 30 of the rubber has a hole therein to accommodate the shaft end 33 off a yoke member y32.l The shatt 33 has a stud 4l] threaded therein. In the upper end of :the shaft 33 there are threaded' three radially extending bronze arms v.34, 35 and 36 (see Fig. 2), in the .slotted ends of 'which are inserted iin members 3l, 38 and 39, respectively. 'That is, the arms 34, 35 and '35 are cylindrical with threaded ends to be inserted in tapped holes at .the upper end of the shaft 33. .'Ihe iin members wedged into the slots at the other ends of the radial arms are of sheet bronze.

rlhese elements are assembled by first placing the lower sponged rubber section 3l) in position in the shell 21 with the cover I0 removed, then inserting the shaft end 33 up through the rubber, .then .threading the arms in position and then inserting the fins in the slots of the arms. The upper rubber section 3| is then placed in the shell 21 and the cover I0 is then inserted and screws .2K6 are tightened. To obtain the desired frequency for .the filtering action, the cover I0 is pressed onto the rubber to the proper deg-ree, provision being made for tightening the cover at any desired posi-tion by the elongated slots 28 in the shell 21. The lower sponged rubber portion 30 extends outside the lower rim of the shell, and the lower sides .are cemented to the shell, as well as to the shaft 313. It has been found that by cementing these portions there is no tendency of the shaft 33 to leave the rubber or the rubber to leave the shell when the inertia of the microphone exerts a pressure on the rubber duri-ng movement of the boom.

At the lower portion of the mount is found a yoke 4Z which has a hole in the upper horizontal portion thereof to accommodate a stud d3 on the lower horizont-al portion of the mem- The yoke 42 is held on the stud by a nut 45 threaded .on the stud 40. The lower ends A of the yoke 42 are connected to an outer ring 46 of the high frequency filter portion of the mount and held thereto by wing nut-and-bolt combinations 41. An inner ring 50 is attached to the outer ring 416 by means of a flexible rubber band l interlaced between the two rings.

Extending upwardly from the inner ring are bracket arms 53 :terminating in a split collar 54 having a tightening scr-ew 55. A spherical type microphone 51 having a cur-ved baille 58, as disclosed and .claimed in copending application S. N. 223,237, filed August 5, 1938, is mounted ron the bracket arms 53 by tightening the collar 54 about the connecting plug 59 of the microphone. An electrical cable 60 leads from the microphone to .an amplifier, as is well known in the art.

LErom the above description it will be noted that there are two mechanical filters connected in series between the microphone 51 and 'the rod 1, the sponged rubber sections 30 and 3i and the `weigh-t of the elements suspended from shaft 33 eliminating the low frequency vibrations, land th-e stretched rubber bands 5| and the weight of the inner ring and microphone eliminating the high frequency vibrations. Thus, when the extendible end of the boom has a tendency to vibrate at a slow period, the upper lter will prevent the vibrations from affecting the microphone, while quick and sharp vibrations will be eliminated by `the lower lter. Also, rotation of the microphone by cable I3 vand spring I9 may set up ycertain vibrations which are damped out and prevented from reaching the microphone with sunicient severity to be picked up thereby.

Another feature of lthe support is the conical shape of the lower portion `of the upper filter which .prevents reflections of sound waves and, consequently, reduces echo effects. 'Ilhis support has given improved results over other types of resilient Inountings and even without the high frequency portions, has been found to be superico to the old types. Since lter mounting may be tuned, it is suitable for microphones diameter yportion attached to one end of said extension and its smaller diameter portion in the direction of said microphone, a suspension shaft for supporting said microphone, a resi-lient material within and interposed between said shell and said suspension shaft and ext-ending around said shaft externally of said sheli, and a plurality of arms embedded in said resilient material and att-ached .to said shaft.

2. A microphone support in accordance with claim 1 in which said arms extend radially from said microphone support :and are connected to fln members extending into sai-d resilient material.

3. A microphone support for minimizing vibration effects on said microphone set up by a flexible extension adapted to be moved foi` adjusting the position of said microphone vcornprising a conical-shaped shell having its larger diameter portion attached to one end of said extension and its smaller vdiameter portion in the direction of said microphone, a suspension shaft for supporting said microphone, a. resilient material within and interposed between said shell and said suspension shaft and extending around sai-d shaft externally of said shell, a. plurality of arms embedded in said resilient material and attached to said shaft, and a closure for said shell for varying the pressure `on said resilient material in said shell for changing the resonant period of said resilient material.

4. A mechanical lter for supporting a microphone suspended from a flexible support adapted vto be moved for adjusting the position of said microphone comprising a conical-shaped shell connected to one end 4of said support, resilient material positioned in .the lower conical portion of said shell, a shaft extending through said resilient material at the other end of sai-d shell for supporting said microphone, a. plurality of removable arms connected to the top portion of said shaft and extending over said resilient material, a second portion of resilient material mounted above said arms and within the upper portion of said shell, and means for covering said shellv and exerting a pressure on said resilient material.

BYRON'F. RYAN.

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