US2123442A - Loud speaker - Google Patents

Description

July 12, 1938; J. M w. STONE v21212354142 LOUD SPEAKER Filed July 24, 1936 2 Sheets-Sheet 1 July 12, 1938. J. Mew. STONE 2,123,442

LOUD SPEAKER Filed July 24, 1936 2 Sheets-Sheet 2 FREQUENCY IN C.P.5.

Patented July 12, 1938 UNiTE STATES F'EENT @FFHQE LOUD SPEAKER linois Application July 24, 1936, Serial No. 92,350

5 Claims.

The invention relates to loud speakers and has among its other objects the provision of a loud speaker which has improved means whereby it may be adjusted with fidelity or to emphasize the desired range of tones.

Another object of the invention is to provide a loud speaker having improved means whereby it may be adjusted in relation to the acoustics of a room so that it reproduces sound in a desired manner.

Still another object of the invention is to provide improved means whereby a loud speaker may be quickly and easily adjusted to reproduce sound in a desired manner.

Other objects and advantages will become apparent as the following detailed description progresses, reference being had to the accompanying drawings, wherein- Fig. 1 is a longitudinal section taken through a loud speaker which embodies the invention.

Fig. 2 is an enlarged fragmentary section taken on the same line as Fig. 1.

Fig. 3 is a section taken on line 33 of Fig. 1, and

Fig. 4 is a diagram illustrating the manner in which the improved loud speaker operates when it is adjusted to operate in two diiTerent Ways.

Referring for the present to Figs. 1 to 3, inclusive, wherein a preferred embodiment of the invention is illustrated, the reference character it designates the front wall of a cabinet of the type commonly employed to house radio receivers. It will be readily understood that the wall Ill functions as a bafile. A loud speaker designated generally by the reference character II is in registry with an opening l2 provided in the wall it. The loud speaker ll comprises a diaphragm or cone i3 formed of any suitable substance such as paper or fabric. Secured to the cone it at the smaller end thereof is a sleeve i5 which carries the voice coil it. The sleeve i5 and the voice coil 58 reciprocate longitudinally of the loud speaker and longitudinally with respect to a central pole piece H which is secured at its rear end to a U-shaped member it forming part of an electro-magnet. The winding of the electromagnet is not shown. Secured to the U-shaped member i8 is an outer pole piece or plate which co-operates with the central pole piece ll to form the annular magnetic gap in which the voice coil 56 reciprocates. The memher is and the outer pole piece 28 are secured to each other and to a metallic basket 22 by a plurality of bolts 24, the basket 22 being provided with the usual apertures 25 so as to reduce the amount it will damp the action of the cone l3.

The basket 22 terminates at its periphery in an annular flange 26, the construction being such that an annular shoulder 21] is formed against which the periphery of the cone i3 abuts. In- 5 terposed between the periphery or marginal portion of the cone l3 and the inner surface of the wall l are a plurality of cardboard rings 28, or the equivalent, which are glued to each other and to the periphery of the cone. The cone IS, the 10 basket and the cardboard rings 28 are secured to the wall it by means comprising a plurality of screws and a plurality of posts 32 which are screw-threaded upon shanks of the screws 38 (Fig. 2). It will be noted that the screws 3%? oo- 15 operate with the posts 32 to clamp the cardboard rings 28 and the marginal portions of the cone i3 and the basket 22 between the posts and the wall it. The inner ends of the posts 32 have screws 33 screw-threaded therein. The screws 33 secure washers 34 to the inner ends of the posts 32.

Slidably journalled upon the posts 32 are grommets 36 which are preferably formed from rubber and are provided with annular grooves 37 whereby they are secured to a housing member or shell 43. It will be noted that when the shell 49 is in the position wherein it is shown in full lines in Fig. 1, it provides a relatively large chamber in back of the basket 22 and it will also be noted that the back end of the shell 59 is spaced a relatively large distance from the magnet structure which comprises the central and outer poles H and 2c, respectively, and the member i8. Secured to the back wall of the shell is a rod or plunger ll, the plunger ii being provided with a knob 42 in back of the shell 46 and being provided with a knob 13 within the cone 53 so that it is accessible tln-ough the hole i2 provided in the wall ill. The back wall of the shell 4B is clamped between the knob 32 and a washer 4 a nut 5 screw-threaded upon the plun er being provided to secure these parts together. The knob 43 is screw-threaded upon the plunger.

The plunger ll projects through a bore 53 extending longitudinally and centrally through the central or inner core ill, the bore being lined with felt 52 so that the metallic plunger 4! will not contact the metal of the inner core ii and thereby affect the reproducing characteristics of 5.0 the loud speaker.

It will be readily understood that one may grasp the knob 42 and draw the shell 4-8 and the plunger ll into positions wherein they are shown in dotted lines in Fig. 1. Such displacement of 55 the shell 50 and the plunger M is permitted by the grommets 36 which slide upon the posts 32.

The marginal portions at the forward end of the shell 40 preferably comprise a cylindrical internal flange and an outwardly extending annular flange 5'5. When the shell 40 is in the position wherein it is shown in dotted lines in Fig. 1, the cylindrical flange 55 encircles the flange 26 of the basket member 22.

Glued or otherwise secured to the smaller end of the basket 22, is a felt ring 58. A damping member 68 which is preferably formed from cardboard and is preferably in the shape of a truncated cone, has its base portion secured to the forward end of the shell M by glue or other suitable means. The inner or smaller end of the damping member 68 terminates in a bead 63 so that the inner edge of the clamping member 68) may engage the felt ring 58 yieldingly.

When the shell 69 is displaced from the position wherein it is shown in Fig. 1 to the position wherein it is shown in dotted lines in the same figure, or to any intermediate position, the damping member 68 is adjusted into a corresponding position as indicated by dotted lines in Fig. 1. Of course, such adjustment may be made by pulling or pushing, as the case may be, on the knob 32 or the knob 33.

When the damping member 65 is in the position wherein it is shown in full lines in Fig. 1, it exercises the'maximum of damping effect upon the cone !3 and when the damping member is in the position wherein it is shown in dotted lines in Fig. 1, it exercises the minimum of damping effect upon the cone is. Obviously, the damping member may be moved to an intermediate position, if desired, to obtain a desired damping effect upon the cone I3.

In Fig. 4 a diagram is shown comprising two graphs W and H. Frequencies in cycles per second are plotted along the base line 12 of the diagram. The decibel variation in intensity of vibration or sound is plotted along the vertical line 13. The graph 70 indicates the action of the loud speaker I I when the shell 48 and the damping member are displaced into the positions wherein they are shown in dotted lines in Fig. 1, it being understood that when the damping member 6E1 is inthe position wherein it is shown in dotted lines in Fig. 1, it has a minimum of damping effect upon the cone E3. The graph 11 rep-resents the action of the loud speaker or cone when the shell 4!! and the damping member 50 are in the positions wherein they are shown in full lines in Fig. 1.

It will be noted that when the damping member is'displaced toward the cone IS, the intensity of the vibrations of the cone l3 at low frequencies is diminished while the intensity of the vibrations of the cone I3 is increased in the higher frequencies. Of course, when the damping member 60 is displaced into positions intermediate the full and dotted line positions of Fig. 1, the action of the cone 13 may be represented by graphs which will lie mainly between the graphs it] and 1 I. In other words, the closer the damping member 60 is brought to the cone IS, the more the low frequencies will be damped and the more the intensity of the high frequencies will be increased.

It will be noted that in graph ii! there is a peak 15 in the lower frequencies. This peak corresponds to the natural mechanical period of the moving system of the loud speaker. When the damping member 60 is displaced toward the cone l3 the peak 15 is diminished more and more. It will be noted that the peak has disappeared entirely in the graph H.

It may be mentioned that the energy which is taken from the lower frequencies is returned substantially entirely to the higher frequencies. It maybe said that the energy represented between the graphs H and 15 at the lower frequencies is substantially equal to the energy represented between these graphs at the higher frequencies.

While certain embodiments of the invention have been shown and described, it is to be understood that it is capable of many modifications. Changes, therefore, in the construction and arrangement may be made without departing from the spirit and scope of the invention as disclosed in the appended claims in which it is the intention to claim all novelty inherent in the invention as broadly as possible in View of the prior art.

Having thus described the invention, what I claim as new and desire to secure by Letters Patent is:

l. A loud speaker comprising an apertured bafiie, a diaphragm mounted on said baffle in registry with the aperturetherein, means for actuating said diaphragm, a housing member providing a chamber in back of said diaphragm, means mounted on said baffle for adjustably mounting said housing member thereon and means disposed in said housing member and movable therewith for damping the diaphragm.

2. A loud speaker comprising an apertured bafiie, a diaphragm mounted on said baflle in registry with the aperture therein, means for actuating said diaphragm, a housing member providing a chamber in back of said diaphragm,

means mounted on said baffle for adjustably mounting said housing member thereon, and an apertured member disposed in said housing member and movable therewith for damping the dia phragm.

3. A loud speaker comprising an aperture-d baflie, a diaphragm mounted on said bafiie in registry with the aperture therein, means for actuating said diaphragm, a housing member providing a chamber in back of said diaphragm, means mounted on said baifle for adjustably mounting said housing member thereon, and a damping member extending transversely of said housing and having a central aperture in registry with the central portion of said diaphragm, said damping member being movable with said housing to control the sound reproduction of said diaphragm.

4. Means for damping a substantially conical diaphragm, said .means comprising a housing member disposed'in back of said diaphragm, means adjustably mounting said housing member,

and a frustro-conical member disposed in said.

housing and movable therewith for controlling the sound reproduction of the diaphragm.

5. Means for damping a substantially conical diaphragm, said means comprising a housing disposed in back of said diaphragm, means adjustably mounting said housing, andafrustro-conical mem ber disposed in said housing and movable therewith for controlling the sound reproduction of the diaphragm, the axes of said conical diaphragm and said frustro-conical member being coincident and said frustro-conical member having a central opening. 77

JOHN MCWILLIAMS STONE.

Images