US1931236A - Art of sound reproduction and distribution - Google Patents

Description

Oct. .17, 1933. A. McL. NICOLSON 1,931,236

ART OF SOUND REPRODUCTIOD AND DISTRIBUTION Original Filed Jime '20, 1927 3 Sheets-Sheet l A/zxander Mqean N/bo/son.

dfbusu Oct. 17, 1933.

A M L. NICOLSON ART OF SOUND REPRODUCTION AND DISTRIBUTION Original Filed June- 20. 1927 3 Sheets-Sheet 2 A/emrx/er M 'lean Nico/son.

O Oct. 17,1933.

A. M I... NICOLSON All! OF SOUND REPRODUCTION AND DISTRIBUTION 3 Sheets-Sheet 3 Original Filed June 20, 1927 4 L 3 n w a m w RI AMPLIFIER fVexanaer M lean Mica/son.

Patented Oct. 17, 1933 c I 1,931,236

UNITED, STATES PATENT "OFFICE ART OF SOUND REPRODUCTION AND DISTRIBUTION Alexander McLean Nicolson, New York, N. Y.,.

assignor to Communication Patents, Inc., New I a v York, N. Y., a. corporation of Delaware .4."

Original application June 20, 1927, Serial No. 199,895. Divided and this application October 30, 1930. Serial No. 492,108

Claims. (Cl. 250-20) This invention is a division of my application It is an object of the invention to provide Serial Number 199,895, filed June 20, 1927, ensuch apparatus which will allow the approach of titled The art of sound reproduction, and parthe ear or ears in intimate and comfortable ticularly relates to the retransmission of electriproximity thereto, and including, if desired,

5 cal signals at the same frequency as received, or means whereby the operator or listener may reat a different frequency to secondary receivers duce the volume to a point such that the sounds in proximity to the listener. produced are clearly and comfortably audible to The general object of the inventionis to make him with his ear or ears in proximity to the the reception of sound signals more'convenient sound reproducing apparatus, but of insufiicient 16 for the listener. intensity to be heard at any substantial distance One of the difficulties of radio reception inthe therefrom. g past has been that of providing comfortable It is still a further object of my invention to audition of radio signals for one who desires 'to provide radio receiving and sound radiating aphear them without disturbing others in the paratus which may be enclosed within a'soft revicinity who may not wish to listen: for example, silient comfortable covering having minimum 70;

one may desire to listen to incoming" radio sig sound absorbing properties, whereby the apparanals at a late hour when persons are sleeping in tus may be used' as a pillow, cushion or the like, adjoining rooms, or in the case of sickness where to permit of the comfortable observation by the quiet is essential. Under such circumstances in listener of the desired sounds clearly audible to the past, it has been necessary for the person him but inaudible to others in proximity to him,

listening to such signals to utilize the so-called without the necessity of wearing head telee head telephones, if quality of reproduction was phones, which covering may include within itself desired. As is well known, head telephones are all apparatus necessary for the reception, selecuncornfortable if worn for any considerable petion, amplification, detection and reproduction of riod: and it is usually the case that if one memradio or like signals at the'desired volume, or

ber of a household desires quiet it becomes necesany desired partof such apparatus. 7 sary to dispense with radio reception during such It is a further object of this invention to properiod. It has been attempted by listeners under 'vide apparatus of the class described and which I such circumstances to obtainloud speaker remay be enclosed within an article of furniture to production by the use of a volume control to render it inconspicuous to permit of such ap-- decrease the intensity of sound radiated to such paratus being disposed in rooms and other places value that it might be comfortably heard by the where such apparatus in its now available form listener but without disturbing others. Howmight be out of place. Still other objects and ever, as is well known, it is not possible under advantages of my invention will be apparent such circumstances to obtain satisfactory quality from the specification. V of reproduction of speech or music, for the rea- The features of novelty which I believe to be son that when the volume is turned down to characteristic of my invention are setforth with such a point that it is inaudible to those in the particularity in the appended claims. My invicinity who do not wish to listen, it is usually vention itself, however, both as to its fundamental 40 inaudibile to the person desiring to listen, or if principles and'asto its practical application will not inaudible the low frequency response is largebest be understood by reference to the specificaly lost and the quality of the sound is distorted, tion and accompanying drawings, in which: the reason apparently being that the low fre- Figures 1, 2 and 3' are diagrammatic views in quency sound waves require a large amplitude partial section of various forms of soundrepro- 15 of motion of the loud speaker diaphragm in ducing apparatus enclosed within a soft resilient order to be propagated any distance from the covering in accordance with my invention, and loud speaker, and such amplitudesare not obincluding sound reproducing apparatus and tainable when the volume is decreased to a point means for controlling the volume of sound resuch that the high frequencies are audible for produced, and Figure 1a isa detail diagrammatic 50 only a' short distance. It results, therefore, that View of a suitable volume control. in order to hear music or speech of good quality, Figure 4 illustrates a slightly different form of the listener must place his ear or ears in ex supporting frame for the resilient and yielding U tremely close proximity to the speaker, and this envelope. close proximity is not obtainable. comfortably Figure 5a is a top plan view partly broken away 55 with the present types of speakers. of an arrangement in which the framework is,

dispensed with, and Figure 5b is an elevation view partly in section thereof.

Figure 6 illustrates a similar arrangement but enclosing within the covering a simple form or radio receiving and detecting apparatus.

' further modified arrangement which may be used in accordance with my invention.

In. accordance with my invention, I provide sound reproducing and radiating apparatus such as a cone,-horn, or sounding board, or a plurality of such devices, adapted to be driven by any suitable mechanism, such for example, as an electromagnetic or electro-static receiver or a piezo-electric device such as a crystal of Rochelle salt, and I enclose this sound radiatingapparatuswithin a covering adaptedto support on its outer surface 'a layer of resilient and flexible material. The layer of resilient and flexible material is preferably made up of a substance or substances having minimum acoustic damping properties, and supported in a suitable manner by an open grille, mesh or similar structure, so as to interfere as little as possible with the radiation of sound, while affording sufficient rigidity to protect the apparatus enclosed-within it. 1

. I also provide a volume control which may be in the form of a variable resistance shunted across the reproducing apparatus whereby the listener may control the volume of sound reproduced, at will.

In accordance with one aspect of my invention, a connection may be provided in the conventional manner to enable the sound reproducing apparatus to be plugged into any suitable radio receiver, electric phonograph, telephone line or the like. In accordance with another aspect of .my invention, such connections may be dispensed with if desired, and a pick-up device may be comprised within or attached to the covering. Under certain conditions, this pick up device may I be in the form of a closed or open circuit adapted to be coupled inductively or capacitively with similar circuits carrying currents of acoustic frequency, and supplied by the output circuit of the radio receiving apparatus, electric. phonoprise a simple t ning system, a crystal o'r other detector, and sound reproducing apparatus as previously described.

In another form of my'invention, such pick 'be given the appropriate shape.

up device may comprise a radio frequency amplifying system, either tuned or untuned, and the desired detecting and audio (frequency amplify-,

ing apparatus as well as the sound radiating apparatus.

Referring now more particularly to Fig. 1, I have shown an arrangement of sound reproducing apparatus in the form of a pillow: in this arrangement, 1 represents a main frame ring of metal, metal tubing, wood, or the like, having the basic shape of the pillow: if a round pillow is desired, the frame or ring may be circular: if a rectangular pillow is desired, the ring 1 may Mounted within this frame or ring 1 is provided, in this instance, a conical diaphragm 2 of suitable material, such as paper, reinforced fibre, or the like, secured to the ring 1 at its periphery by means of an annular hinge 3 of flexible material, such as cloth, paper, leather, or the like. Suitable brackets,'braces or cross arms 4, may extend inwardly from the ring 1 to some interior point such as the center for the purpose of supporting a suitable driving mechanism 5 for operating the diaphragm by means of a connection 6. driving mechanism 5 may be an electro-magnet of the usual type, or it may comprise an electrostatic driving mechanism, or a piezo-electro crystal device of the types known in the art.

For the purpose of protecting the diaphragm and the mechanism contained within the pillow, and also for the purpose of providing a firm foundation upon which may be built a yielding and resilient surface, I provide a pair of cover members 7 and 8 adapted to be secured in position on opposite sides of the ring 1. The cover members? and 8 are preferably constructed in a manner to provide the necessary or desired mechanical rigidity while at the same time interfering as little as possible with the radiation of the sound from diaphragm 2, For this purpose, these members may be built up of wire mesh of sufficient strength, perforated metal plates, wicker .work, or the like, affording relatively large mechanical strength while at the same time presenting minimum impedanceto the passage of sound waves therethrough. In order to provide for a resilient and yielding surface, the members 7 and 8 may be covered with a layer of cloth 10a such as cheese cloth, muslin, or the like,

affording a bed upon which may be built a layer of resilient and sound conducting material 9.

In order to obtainthe best results, the layer of material 9 should be sufiiciently thick to provide a yielding and resilient surface against which the ears or other members of the body of the listener may be reposed in comfort, while at the same time, this layer of material should not introduce any considerable damping upon the sound waves, at any acoustic frequency. Various materials may be used for this purpose, but I have found that the most satisfactory material is evergreen foliage, such as balsam, hemlock or arbor vitae, pine needles, and the like. planation of the superior results obtained from this material in comparison with other materials, is not entirely clear, but is probably, due to the fact that evergreen foliage in quantity between The The theoretical exspaced surfaces of cloth or similar material, provides a relatively resilient and yielding structure,

in free air,'whereas in the case of materials in which the air spaces are relatively smaller'and are more completely filled with material, free movement of air pressure therethrough is thereby hindered or prevented. At any rate, whatever the theoretical explanation may be, I wish to note the fact that best results are obtained with the materials specified. After a layer of the desired depth of such material has been built up, for example 1 or 2" in thickness, an outer covering 10b may be attached,

and finally if desired, an ornamental or decorative cover may be applied over all, the ornamentation or decoration being chosen to suit the taste and to harmonize with the setting in which'the apparatus is to be used, without interfering with the free passage of sound.

For the purpose of controlling the operation of the device, leads 11 and 12, through which currents of audio frequency are supplied to cause operation of the device, may be provided with a suitable by pass 13, herein diagrammatically shown as resistance, but it will be understood that an inductance and capacity or any combination of those, may be provided. A suitable control for the by-pass 13 is extended to the exterior of the pillow, for example in the manner shownin Figure 1a, wherein there is provided a resistance suitably mounted in the form of an arc and adapted to be' traversed by a contact arm 14 mounted upon a suitable shaft 15, in'turn carrying a disc 16, to which cords or chains 1'7 are attached. Said cords or chains may pass through suitable openings in the members 7 and 8 and the resilient covering therefor and may terminate in knobs, tassels, or thelike, such as 18 and 19. In the operation of the device, the leads 11 and 12 are suitably connected to a source of audio frequency currents such as the output of a radio receiver, a telephone line, an electric phonograph, or the like, which as will be readily understood, causes vibration of the diaphragm 2, thereby propagating sound waves through the resilient and yielding cover into the open air. If a relatively large volume of sound is desired, as may be the case when several people wish to listen, impedance of the by-pass 13 will be made a maximum by operation of the controls: if, on the other hand, one desires to listen without disturbing others, the impedance of the by-pass may be adjusted to such value that the intensity of the sound is diminished to the point. desired: and it may be decreased to such a point that the operator may place his ear or ears in intimate and comfortable proximity to the diaphragm 2 simply by reclining his head against the pillow in the ordinary manner, and under such conditions the quality of sound radiated to the ear of the listener will be substantially the same as that radiated to the ear of thelistener in the usual manner.

Referring now more particularly to Figure 2, I have shown a horn type of reproducer 25 in place ofthe cone 2., By coiling the horn upon itself, it is possible to obtain a horn of relatively great length and wide frequency response, with consequent improvement in quality, as is known in the art: in this instance, braces 26 may maintain the horn and operating mechanism in the desired position. As in the arrangement shown in Figure 1, a pair of supporting members 7 and 8 are provided over which is formed a layer of resilient material andthe outside coverings, as already described. In addition, a suitable volume control may be provided having its controls extending outwardly through the outer covering as is also the case for leads 11 and 12. v a

Referring now more particularly to Figure 3, I have shown a similar arrangement except that in this instance the sound radiating element com-1 prises a relatively large -plain diaphragm 27, which may be a true diaphragm operating as such and constructed of anydesired material such as metal, balsa wood, or the like, or may be sufliciently thick and so arranged asto constitute a sounding board.

Referring now to Figure 4, I have shown an arrangement in which, instead of a framework of wire mesh, or thelike, I have utilized apressed or formed member for example, of fibre, composition or the like, made in sections '7 and .8 as before, but provided in this instance with a depression on one side '71 adapted to receive the head of the listener and also provided with a plurality of perforations 70 to permit free transmissions of sound waves therethrough.

While Ihave shown a large diaphragm as the sound radiator in this figure, it will be understood that other radiators such asthose previously referred to may be used in this arrangement if desired.

Under certain conditions, it may be desired to dispense with the supporting envelope, and such an arrangement is shown in Figures 5a and 5b. In'this instance, I provide a horn 80, attached to the speaker unit, which horn may be mutilated to provide a dished portion 81 which may be so constructed as to act as a sounding board, and also as a support for the flexible envelope. The horn 80 may be provided with a plurality of'holes or openings 82 of any desired shape and disposition for the purpose of modifying the quality of the sounds reproduced, and of 1 allowing free distribution thereof to the atmosphere. For the purpose of preventing the filling of the envelope from clogging the horn, the horn may be enclosed in a covering 83 of relatively thin and porous cloth such as cheese cloth, muslin or the like. A vol-v ume control will preferably beprovided as 'here elements of asimple radio, receiving set, such for example as inductance 31, capacity 32 and a crystal or other detector 33 which may be con nected in the circuit shown in Figurev 7a: antenna and counterpoise or ground'conductors may be attached to the pillow in the form of ribbons, streamers'and the like, or a suitable loop antenna may be formed within the covering .or otherwise attached thereto. In Figures 7a, 7b, and 7c, 35'represents anantenna connected at one end of the coil. 31; 37, a counterpoise connected at the other end of said coil; 32,. a condenser in shunt'therewith; 33, a suitable detector such as a crystal; 38, a by-pass condenser, utilized if desired; and 5 and 27,respectively represent the driving mechanism and sounding board as shown in Figures 3 and 6. It will be understood that the arrangements shown in Figures 1 and 2, 4, 7a and 712 may be utilized, or other adapted to be connected selectively in circuit by a suitable contact 40 secured to disc 41, and opconnected in circuit by means of a similar contact 40, the position of which is controlled by pull chains 42 and 43: similarly, snap switches may be substituted for the arrangement shown, or a continuously variable condenser may be utilized. 1

The arrangement of Figure 6 will provide satisfactory reproduction of signals, from nearby broadcasting stations, particularly when it is not.

desiredto produce a large volume of sound. In case it is desired to effect loud speakerreproduction from distant stations, the arrangements shown in Figures 8 and 9 may be utilized.

Referring now more particularly to Figure 8, I have shown radio receiving apparatus of the conventional type comprising antenna 35 including coil 31 forming the primary of a suitable input transformer leading to a radio frequency amplifier 61, the output of which is supplied to a detector 62 and the detector currents from which are amplified by a suitable audio amplifier 63: instead ofphysically connecting the sound reproducing device to the output of the audio frequency amplifier, the output currents may be supplied to a suitable open or closed circuit 47 which may be in the form of. wires leading to any desired point, and to which similar wires included within the pillow may be inductively or capacitively coupled. This permits the movement of thepillow as desired without restriction due to length of connecting leads, and also permits the use of a plurality of speakers operated by the same receiver. 7 i

It may be desired to provide one or more stages of audio frequency amplification within the pillow for the purpose of overcoming the losses in the transfer of energy from the output of the audio amplifier to the pick-up system of the pillow: and in'this instance, such apparatus may be mounted within the pillow in substantially the manner shown in Figure 6.

Under certain conditions it may be desired to utilize a plurality of such-pillows, each receiving and responding to a different transmitter; in

such case, there may be provided a radio frequency amplifying system 64 adapted to receive and radiate signals at radio frequency, either on the same frequencies as received, or on different frequencies. For this purpose, there may be provided a radiating circuit 48 attached to the output of the amplifier: the amplifier itself may comprise aituned system selectively amplifying at one frequency, or an aperiodic amplifying system amplifying all incoming frequencies: or it may be in the form'of a heterodyne which may increase or decrease the frequency'ofall incoming signals by any desired amountwhich new frequencies amplified if desired, may be radiated through the radiating circuit 48. The receiver in such case will preferably comprise a pick-up system with or without radio frequency amplification, a selecting system, a detector, and if desired an audio frequency farnplifying apparatus. Su'ch receiver may be utilized also to reproduce signals received from a radio phonograph as shown in Figure 9, which may conveniently comprise a thermionic vacuum tube oscillator 50' having an input circuit comprising coil 51 and a condenser 52 provided if desired, with. antenna 53 and counterpoise 54 of relatively small size. The input circuit may be connected between the cathode 53 and the control. electrode 56, and an output circuit is connected between anode57 and extends'through a suitable feedback coil 58 and a microphone or magnetic pick-up 59 provided with a stylus adapted to .be driven by a suitablerecord. The plate circuit. is completed through a suitable source of potential for feeding space current and heating the current'to the oscillator 60. As will be understood, the microphone or magnetic pickup 59 serves to modulate at audio frequencies the radio frequency oscillations generated by the oscillator 50 which are radiated by the radiating system comprising antenna 53 and counterpoise 5e and the radiated oscillations are picked up by the receiver, detected, amplified if desired, and converted into sound of the desired volume.

Under certain conditions, it may be desired to mount the entire apparatus comprising radio frequency amplifier 66, detector 67, and audio frequency amplifier 68 within the pillow as shown in Figure 10, in which case a suitable loop may be attached to the fabric, or similarly secured to the pillowor an open antenna and counterpoise circuit or ground may be provided in'the form of streamers, having metallic conductors provided therein attached to the pillow: in any event, the controls for volume and selectivity will preferably be provided in the form of chains, cords or the like, extending out of the pillow, and either sufficiently inconspicuous asto be unnoticeable, or decorated in a manner to harmonize with the decorative effects thereupon.

While I have shown and described the devices herein as a pillow,.it should be understood that my invention is not limited thereto but contemplates the provision of an upholstered envelope of any sort, which may be an article of furniture, such as a chair, and which includes in a recess therein, an acoustic radiating system; and also if desired, means for controlling the volume within any desired range; and also, any necessary or desired audio frequency amplifying apparatus, detecting device and a radio or carrier frequency amplifying apparatus, together with the neces-' a portable head pillow having a soft resilient covering over a framework, an antenna within said framework, a signal detector and amplifierof said local signals attached to the interior of said framework; means for tuning said, receiver, and a sound reproducer located within said pillow for reproducing said signals for anobserver lying upon said pillow.

2. In a signal distributing system buildings and the like, an antenna for receiving broadcas.

signals, means for detecting and amplifying said signals, mean's'for locally broadcasting said signais electromagnetically to local receiving points, a portable head pillow having a soft resilient covering over a framework, an antenna within said framework, a signal detector and amplifier of said local signals attached to the interior of said framework, a sound reproducer connected to said amplifier and located within said pillow for reproducing said signals for an observer lying upon said pillow, a volume control located within said pillow, and means connected to said volume control and extending externally of said pillow for adjusting the volume of said reproducer while in use.

3. In a signal reproducing system for a plurality of listeners in different rooms of a building, the combination of a plurality of portable pillows having soft resilient coverings and interior frameworks to form spaces therein, an antenna, signal detector and amplifier attached to said framework in eachof said pillows, a sound reproducer in each of said pillows, a master signal receiver in said building having means for broadcasting the output of said receiver to the antennae in said pillows, and means external of each pillow connected to respective volume controls for adjusting the outputs of each reproducer in accordance with the distance of each pillow from said master receiver while said pillows are in use.

4. In a signal distributing system for local areas, an antenna for receiving broadcast signals, means for detecting and amplifying said signals, means for locally broadcasting said signals to local receiving points, a portable head pillow having a soft resilient covering, means located within said pillow for detecting and amplifying said local signals, means for tuning said receiver, and

a sound reproducer located within said pillow for reproducing said signals. V

5. In a signal distributing system for local areas, an antenna for receiving broadcast signals,

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