US2325424A - Windshield for microphones - Google Patents

Description

July 27, 1943- M. RETTINGER WINDSHIELD FOR MICROPHONES Filed Jan. 29, 1941 INVEN TOR: .M/CHAEZ .Esrrnvsse; BY

A TTORNEYS.

Patented July 27, 1943 WINDSHIELD FOR MICROPHONES Michael Rettinger, Encino, Calif., assignor to Radio Corporation of America, a corporation of Delaware Application January 29, 1941, Serial No. 376,509

(Cl. 179-l88) 8 Claims.

This invention relates to sound pickup apparatus such as microphones, and particularly to Windshields or screens for protecting the microphones responsive element, such as a diaphragm or a ribbon, from the noise of air turbulence around the microphone or adjacent apparatus during operation,

The general use of Windshields or screens for microphones is well known, such a screen being disclosed in U. S. Patent 588,034, of August 10, 1897. Such a windscreen construction, however, is ineificient and not suitable for the modern sensitive type of microphones. A later method of and means for protecting a microphone is disclosed in U. S. Patent 1,987,413, of January 8, 1935, this latter type of screen illustrating the use of a double Wind protector and disclosing the particular relationship between the openings in the screen and the solid portion thereof.

The present invention is a further improvement of the method of and means for protecting a microphone when used outdoors in a strong wind or on motion picture sound stages wherein artificial Winds are produced. The invention utilizes the double windscreen feature to a limited extent, but is primarily concerned in providing a method of and means for automatically pointing the microphone with respect to the direction of the wind whereby the highest efficiency of the screen is obtained.

The principal object of the invention, therefore, is to facilitate the screening or shielding of a microphone or other type of sound pickup apparatus from the effect of air currents.

Another object of the invention is to auto- A further object of the invention is to provide a microphone windshield which is under control of the direction of the air currents for positioning the shield toward the direction of motion of the air currents.

Although the novel features which are believed to be characteristic of this invention will be pointed out with particularity in the appended claims, 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 Figure 1 is an elevational view of the invention;

Figure 2 is a cross-sectional view of the invention; and

Figure 3 is across-sectional detail view taken along the line 3-3 of Figure 2.

Referring now to the drawing in which the same numerals identify like elements, a microphone 5 is shown mounted upon a rod or shaft 6 which is rotatable upon a ball bearing '1. The ball bearing 1 is mounted on a coupling 8 threaded on a supporting rod 9, which, in turn, may be adjustably mounted upon an extension I I such as the end of a boom or other supporting means for the microphone. The microphone 5 has positioned in the front portion thereof a screen 14 of a curvature conforming to the general spherical curvature of the microphone 5.

Surrounding the microphone 5 is a spherical windscreen 15 whose center is substantially concentric with the center of the microphone 5 and which is mounted upon a sleeve IE on the shaft 6. The screen I5 is preferably of perforated metal covered with a thin silk fabric. The sleeve I5 is integral with a windvane l 8 and may be fixedly positioned to the shaft 6 by means of a set screw H! (see Fig. 3), the end of which is inserted within a reduced diameter portion 20 of the shaft 6.

The windscreen l5 has one section thereof cut away, as shown at 22, to facilitate the reception or impression of the air waves upon the actuating element in the microphone 5. Although the screen l5 may be solid Without the opening 22. it has been found that such an opening increases the overall efficiency of the microphone and prevents the normal microphone frequency characteristic from changing. The present invention permits advantage to be taken of the use of such an Opening in the windscreen.

Referring now to Figure 2. it will be observed that the shaft 6 has an enlarged diameter por-- tion at the point 24 for supporting the microphone and associate elements upon the bearing 1. Thus, the microphone 5 and shield l5 may be freely rotated upon the bearing 1 by the windvane l8 when actuated thereby by air currents, and with the set screw 19, as shown in Figure 3, tightened against the shaft 6, the windvane [8 will position both the microphone 5 and the Windscreen 15 into the direction of the wind. However, by loosening the set screw 19 and tightening a set screw 28 bearing against the upper portion of the shaft 6, the microphone shaft may be maintained stationary and the vane [8 will control only the windscreen $5 with respect to the direction of the Wind. Thus, for small variations in wind direction, it is more efficient to adjust on y Windscreen IS with respect to a fixed positiOn of the microphone 5,- while, in cases where there are large variations in wind direction, or in cases where the microphone support H is moved, better results may be obtained by rotating both the microphone and the shield I5 with respect to the air currents.

Although the microphone is generally used in the solid-line position shown in Figure 1, it may also be used in the position shown in the dotted lines in Figure 1, in which case the weight of the microphone 5, screen [5 and vane i8 is supported upon the bearing 1 by the keyed collar 21.

By the use of the above-described windshield or screen, protection is obtained against the whistling noises of the air around the microphone itself, the spherical form of the screen eliminating any square corners or edges which would create air turbulence. Also, by the use of an opening 22 in the screen 15, ther is substantially no reduction at the high frequency end of the audio spectrum caused by the screen interfering with the passage of the high frequency air vibrations through the metal shield and silk fabric. By automatically controlling the position of the opening 22 by the vane l8 with respect to the direction of the air currents, the shield is always positioned at its most efiicient operating position. Although the shield l 5 is shown spherical with an opening, it is to be understood that other shapes of shields may be similarly controlled.

What I claim as my invention is:

1. A windshield for a microphone comprising a rotatable element interposed between the wind and the microphone in the direction from which said wind is blowing, said element having an opening therein to permit sound waves to be impressed upon said microphone without obstruction, and means for maintaining said element in said position regardless of changes in the wind direction.

2. A windshield in accordance with claim 1. in which said element is a perforated screen partially surrounding said microphone.

3. A windshield in accordance with claim 1 in which said last-mentioned means is a windvane attached to said element for rotating said element by wind energy.

4. The method of shielding a microphone from wind varying in direction during the use of said microphone, the shield having an opening therein to permit a substantially unobstructed impingement of sound waves on said microphone, comprising positioning the opening in said shield in line with an opening in said microphone, and utilizing the energy of the wind motion to maintain said openings in a line coincident with the line of the direction of said wind.

5. An automatic system for preventing air turbulence around a sound pickup device having an opening therein comprising a shield partially surrounding said device and positioned on the side of said device toward the direction of air movement, the opening in said shield being adjacent the opening in said pickup device and'means for rotating said device and shield to maintain the relative positions of said device and shield with respect to the direction of air movement as the direction of air movement varies.

6. An automatic system in accordance with claim 5 in which said shield is a perforated screen of a spherical shape.

ically shaped screen covered with a silk fabric,

and said last-mentioned means is a vane attached to said screen, the position of said vane being controlled by the direction of air movement.

8. A device for shielding a microphone having an opening therein from wind varying in direction during the use of said microphone comprising a shield surrounding said microphone and having an opening therein, means for utilizing wind energy to maintain said shield opening away from the direction of the wind, and means for connecting and disconnecting said microphone and shield, said microphone and shield being disconnected during small variations'in wind direction so that said shield opening varies in position with respect to said microphone opening and said microphone and shield being connected during large variations in wind direction to maintain said openings in line with each other.

MICHAEL RETTINGER.

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