US2890297A

US2890297A - Transducer assembly

Info

Publication number: US2890297A
Application number: US615107A
Authority: US
Inventors: Philip N Lehr
Original assignee: DICTOGRAPH PRODUCTS CO Inc
Current assignee: DICTOGRAPH PRODUCTS CO Inc; DICTOGRAPH PRODUCTS COMPANY Inc
Priority date: 1956-10-10
Filing date: 1956-10-10
Publication date: 1959-06-09
Anticipated expiration: 1976-06-09

Description

June 9,1959 P. N. LEHR TRANSDUCER ASSEMBLY 2 Sheets-Sheet l Filed Oct. 10, 1956 m T w W.

PHILIP N. LEHR his ATTOR r am NEYS

June 9,1959 P, NLEHR 2,890,297

TRANSDUCER ASSEMBLY Filed Oct. 10, 1956 2 Sheets-Sheet 2 INVENTOR. PHILIP N. LEHR r ATTORNEYS United States Patent TRANSDUCER ASSEMBLY Philip N. Lehr, Huntington, N.Y., assignor to Dictograph Products Company, Inc., Jamaica, N.Y., a corporation of Delaware Application October 10,1956, Serial No. 615,107

4 Claims. 01. 119-119 This invention relates to transducer assemblies for reproducing or responding to acoustic energy. More particularly, it relates to small transducer assemblies for operating rather close to the user under difficult conditions such asmight be encountered, for example, in the case of a. hospital patient speaking through orlistening to the transducer while it is supported on or near the bed.

Portable transducer assemblies for use in or about beds tend to be limited in their performance characteristics due to such factors as size limitation, the necessity of withstanding abuse, and the likelihood of mufiling by the bedding. Thus the assemblies must be compact and preferably of light weight; they must the robust in cou' structio-n; and, if they are to be wholly useful, must be capable of reproducing or responding to a reasonable range of frequencies even when partially smothered in the bedding. Preferably, they should be capable of operation both to reproduce sounds for the patient to hear, 'such as music or instructions, and, selectively, to reproduce the sounds by the patient for the ears of a centrally located nurse, for example. In the latter case, the trans: ducer assemblies should be capable of achieving at least someresponse to sounds, no matter how theassemblies mightbe oriented with respect to' the sound source.

In accordance with the present-invention, therefore, there is provided a transducer assembly including a pair of companion housing parts each of generally dished conrelatively soft compliant surface such as a pillow with relatively little possibility of all ports being blocked. Furthermore, the sizes and numbers of the ports communicating with the closed chamber and the front of the speaker can be so arranged that reinforcement occurs in: the bass frequency range of the speaker, thereby to extend its range, while at the same time presenting access to the cone from all directions.

The speaker can be mounted within the chamber defined by the companion housing parts with its mouth portion engaging the insideface of the front part and with its magnet or driver portion engaging the inside face of the back part, thereby bridging the distance therebetween. Also, complementary recesses can be provided in the margins of the companion housing pieces to receive fixedly the end sleeve or molding of an electrical cord.

. 'A' representative embodiment of the invention from figuration and formed of a tough durable material. The

parts are brought together with their respective concave surfaces in opposition to define-a shallowfully enclosed chamber for receiving the transducer, commonly called the speaker, across its depth. The front housing part-includes a central gently rounded portion pierced by a cluster of ports or openings which pass acoustic energy directly to or from the speaker cone. Beyondthis' central area and beyond the mouth of thecone, radially speaking, are another series of ports which communicate with the chamber and hence with the back surface of the cone in the manner of bass reflex enclosures.

The back housing part is formed with a'flat central supporting surface on which the assembly can rest, as

ports in larger speaker on a pillow, for example, with the portions beyond the 1 supporting surface tapering rather steeply toward the edges which abut the front housing part. Formed in the tapering portion well spaced from the flat surface, are a series of ports which also communicate with the closed chamber and hence the back surface of the speaker cone.

which, the above and other features will be readily understood by those skilled in the art is described below having reference to the accompanying drawings in which:

, Figure 1 is a front view of a transducer assembly;

' Figure 2 is a view in vertical section taken on the line 2-2 of Figure 1 looking in the direction of the arrows; Figure 3 is a back View of the assembly of Figure l; and

Figure 4 is a view in transverse section taken on the line i 4 of Figure 3, looking in the direction of the arrows.

Referring to the drawings, the invention is illustrated as embodied in a transducer assembly indicated generally by the numeral 10 and comprised of a pair of companion housing parts including a front part 11 of generally dished configuration with its convex surface facing outwardly and, edgewise abutted thereto and secured as by cementing or detachable fasteners (not shown) a back part '12 also of dished configuration and having its convex surface facing outwardly. The housing parts 11 and 12 are preferably formed from a tough, durable material such as plastic, all exposed surfaces being free of pronounced irregularities or projections which might become fouled in the bedding or cause discomfort or injury to the user.

The 'abutting edges of the two housing parts are preferably held to close tolerances during fabrication to insure a tight fit, and suitable shoulders are included to prevent relative lateral displacement.

The mated housing parts 11 and 12 define a closed chamber 13 across the maximum depth of which extends atransduce'r in the form of a loud speaker 14 having its mouth ring 14a abutting or, if desired, secured to the inside surface 11a of the front housing part 11 and its rear-most frame part, the latter taking the form of a magnet 14b, attached as by screws 15 to the inside face 12a of the backhousing part 12. The diameter of the speaker 14 at its largest point is smaller than the diameter of the front housing part 11 so that the chamber 13 extends radially beyond the limits of the speaker 14.

The face of the front housing part 11 is formed with a dense cluster of ports or openings 16 all disposed within the area circumscribed by the mouth 14a of the speaker 14. Thus, acoustic energy from or to the front of the speaker cone or diaphragm 14c, nested within a spider or frame 14a, passes only through the openings 16. Also formed in the front face of the housing part 11 are a 5 series of openings 17 communicating with that portion of the chamber 13 which is outside the confines of the speaker mouth 14a, the openings 1'! in the illustrated embodiment being arranged circumferentially-about the 3 speaker axis on a radius larger than that of the speaker mouth.

The back or rear housing part 12, as best seen in Figure 3, is formed with a generally flattened surface 12a on which the speaker can rest and to which, as described, magnet 14b can be bolted. So arranged, it will be seen that the mated housing parts 11 and 12, being secured to the front and back, respectively, of the speaker, augment the framework of the speaker, including the spider, for example, thereby reducing resonances. If desired, a name plate or other suitable indicating means can be affixed to the flat back surface of the back housing part 12, this surface serving also as a support on which the transducer assembly can be rested. Surrounding the flat center portion of the back housing part 12 is a curving portion 12b tapering toward the outside perimeter of the housing assembly. Formed in the tapering portion 12b at points close to the outermost extremes of the chamber 13 radially speaking are a series of ports or openings 18. Both the openings 17 in the front housing part 11 and the openings 18 in the back housing part 12 are arranged to pass acoustic energy to or from the back of the cone 14c of the speaker 14. It will be observed that the number of openings 16 accommodating acoustic energy to or from the front of the cone 14c greatly exceed the number which accommodate energy to or from the back of the cone. The relative areas of the

openings

16, 17 and 18, the inherent performance characteristics of the speaker 14, the size of the chamber 13, and the natural resonances of the housing parts 11 and 12 are such that a reflex principle obtains which greatly improves the base response of the assembly. In view of the over-all size of the assembly, which can be approximately five inches in diameter and two inches in thickness, the frequency range, particularly in the lower limits, has been found to exceed that normally obtainable with assemblies of commensurate size.

The assembly is adapted to be operated without any appreciable loss in efiiciency when resting on very compliant surfaces such as pillows. At the most, some or all of the openings 18 might become blocked by the pillow. In these circumstances, both the direct radiation openings 18 and the reflex openings 17 can operate. In other positions 'in the bedding, larger percentages of the

openings

16, 17 and 18 might become blocked. Regardless of how the assembly is disposed among the bedding, however, it is unlikely that all of the openings16, 17 and 18 will become fully blocked, so that at least some energy can pass to or from the speaker. Also, because the speaker unit 14 is rigidly secured between the mated housing parts, the housing itself can be utilized to radiate limited amounts of acoustic energy.

Because so-called pillow speakers are often used to convey messages to patients in hospital beds through an intramural communication system, as well as to transmit sounds from the patient back to a nurses desk, for example, it is important that the speaker assembly not be rendered completely inoperative by the bedding. A speaker closure formed in accordance with the present invention can conveniently be hung at the bedside, as on the bed head, for example, or it can be rested front face up on the pillow beside the patient, with good acoustic effects.

The front and back housing parts 11 and 12 can be formed with

opposing recesses

19 and 20 to receive a molded plug member 21 at the terminal end of anelectrical cord 22. Preferably, plug 21 is tightly secured to the housing as by set screw 23, for example, to prevent inadvertent detachment in the event of rough handling.

While the invention has been described above having reference to a preferred embodiment thereof as illustrated in the drawings, it will be understood that it can take various forms and shapes without departing from the spirit of the invention. The invention should not, there- 4 fore, be regarded as limited, except as defined by the accompanying claims.

Iclaim:

1. In a small, portable transducer assembly, a housing having a transducer chamber therein, a first port means in the front face of the housing, a second port means in the front face of the housing arrayed about the first port means, means to mount a transducer in the cavity facing the first port means, said second port means communicating with the cavity beyond the front face of the transducer, third port means in the back face of the housing communicating with the cavity, said second and third port means having a total port area which is considerably less than the port area of the first port means, said housing being generally convexly rounded with the marginal portions of the back face converging toward the marginal portions of the front face, and said third port means being formed in the marginal portions of the back face.

2. A small portable transducer housing assembly particularly adapted for use in and about beds, comprising a generally convexly rounded housing flattened in profile, and generally circular in full face projection, said housing having an internal cavity defined by a pair of generally flattened opposing inner surface portions flanked by convergent wall portions which meet near the periphery of the housing, a transducer centrallymounted in the cavity to bridge the distance between said flattened inner surface portions and being supported at its opposite ends, said transducer including a diaphragm facing the inside of the front face of the housing and a base portion facing the inside of the back face of the housing, a cluster of first ports piercing the front face of the housing and communicating exclusively with the forwardly facing surface of the diaphragm, a series of second ports piercing the front face of the housing and communicating with the cavity, thereby communicating with the back surface of the diaphragm when the housing is in use, a series of third ports piercing the back surface of the housing and communicating with the cavity and the back surface of the diaphragm, and said third ports being formed in the convergent wall portions of the housing, whereby the assembly can be rested on a supporting surface, back face down, without blocking the third ports.

3. A small portable transducer housing assembly particularly adapted for use in and about beds, comprising a generally convexly rounded housing circular in full face projection and flattened in profile, said housing comprising dished front and rear housing portions of generally the same size and configuration joined at their peripheries with their concave surfaces opposing one another to define an internal cavity, said opposing inner surfaces including generally flattened central portions and converging marginal portions, a transducer mounted in the cavity and including a vibratable conical diaphragm abutted against the flattened portion of the inner surface of the front housing portion and an electromagnetic driver coupled to the diaphragm and secured at its back portion to the flattened inner surface of the rear housing portion, a cluster of first ports piercing the flattened portion of the front housing portion and communicating with the forwardly facing surface of the conical diaphragm, a series of second ports piercing the front surface of the housing portion and circumferentially arrayed about the cluster of first ports and communicating with the cavity outside the peripheral limits of the conical diaphragm, thereby communicating with the backsurface of the diaphragm within the cavity, and a series of third ports piercing the converging marginal portions of said rear housing and communicating with the cavity and hence the back surface of the diaphragm, said second and third ports having a total port area which is considerably less than the total port area of the first ports.

4. A transducer assembly as set forth in claim 2, said transducer including a spider frame supporting the conical diaphragm, the spider frame being supported at its forward portion by the front housing portion and at its rearward portion by the base of the transducer and by the back housing portion, whereby the housing reinforces the spider frame to suppress resonances.

References Cited in the file of this patent UNITED STATES PATENTS Kettler July 15, 1952