US2152915A - Telephone instrument - Google Patents

Description

April 4, 1939. H. c. PYE

TELERHONE IIIS'IRUMEIIT File d Feb. 6, 1937 Sheets-Sheet 1 INVENTOR. HAROLD C. PYE

' 'ATTCRNEYGV.

April 4, 1939. l-L'c. PYE 2,152,915

TELEPHONE INSTRUMENT Filed Feb. 6, 1937 s Sheets-Shea. 2

, INVENTOR: HAROLD C. PYE

. gal g. W V I ATTORNEYS.

H. C- PYE ELEPHONE INSTRUMENT Filed Feb. 6, 1937 April 4, 1939.

3 Sheets-Sheet 3 FIG. 8

FIG. 6

FIG. 9

FIG. 7

INVENTOR. HAROLD C. PYE

ATTORNEYS.

Patented Apr. 4, 1939.

PATENT OFFICE r 2,152,915 rnmrnona msrammn'r Hal-old C. Pye, Oak Park, 111., assignor to Associated Electric Laboratories, Inc., Chicago, 111., a corporation of Delaware 9 Application February a, 1931, Serial No. 124,425

6 Claims. (01. 179-403) The present invention relates to telephone instruments and more particularly to the hand set;

type of instrument employed with the cradle type of telephone.

Various forms of instruments of the general type noted are commercially available, all of which operate in a more or less satisfactory manner insofar as their electrical and acoustical characteristics are concerned. In at least one conventional form of hand set now widely used, all of the exposed parts, comprising the handle, the mouth piece and the ear piece, are constructed of moulded insulating material such as that sold under the trade-name "Bakelite", the various terminal members and the conductors interconnecting the same being embedded in the moulded compound. This form ofinstrument, while desirable from the viewpoint of insulating the user from the electrical circuits of theset, possesses various structural defects and presents certain definite manufacturing diillculties. Thus, in the usual instrument of the specific type mentioned, the cord terminal terminates at one end of the set and the conductors .extending therefrom to the instrument cell at the other end are bare conductors embedded in the moulded handle, which conductors are susceptible of becoming entangled and electrically interconnected during the moulding process, whereby the finished product is necessarily defective and must be rejected. A further structural deficiency resides in the insubstantial supporting of the transmitter and receiver assemblies or cells, thereby detracting from the ruggedness of the instrument. Another characteristic feature which further detracts from the ruggedness pertains to the Bakelite screw threads by which the ear and mouth pieces are conventionally secured to the cups individually housingthe receiver and transmitter cells. This method of attaching the ear and mouth pieces to the respectively associated cups also lends itself to ready disassembly of the instrument thus enabling unskilled persons to take the instrument apart and expose the delicate working parts to dirt, moisture, and improper handling. Dirt and moisture, more specifically the latter, also have ready access to the transmitter cell diaphragm through the sound transmission holes normally provided in the mouth piece and in other parts interposed between this piece and the transmitter cell diaphragm. The resulting accumulation of. dirt and, moisture on the transmitter diaphragm may adversely ailect theire- I quency response of the latter'to the acoustical vibrations causing its operation, thereby detracting from the transmission fidelity.

It is an object of the present invention, therefore, to provide a telephone hand set comprising transmitter and receiver cups, self-contained transmitter and receiver cells arranged in the corresponding cups, mouth and ear pieces associated with the corresponding cups, and improved arrangements for securing each of the cells in its corresponding cup independently of the mouth 10 or ear piece associated therewith.

It is-another object ofthe invention to provide an improved telephone instrument of the general type noted which is of simple and economical construction and is free of the various mechanical 16 deficiencies outlinedabove.

More specifically, it-is' an object of the invention to provide an improved telephone hand set which may easily be manufactured in production quantities .with a minimum number of defective 2o instruments "and which has one or more of the following characteristics: rugged construction, protection against dirt and moisture, and protection against unauthorized disassembly by unskilled persons. 26

In brief, the objects as generally set forth above are attained in accordancewith the present invention by providing various structural improvements for an instrument of the general type noted and comprising transmitter and receiver cups 30 onstructed of insulating material and individually including contact members, together with self-contained transmitter and receiver cells including contact members for individually engaging the corresponding contact members of the 85 corresponding cup. The usual ear and mouth pieces or members are also provided which similarly are constructed oi insulating material.

' These improvements relate in part to the method and means whereby the instrument is assembled. 40 Thus, each of the transmitter and receiver cells is provided withmeans for securing it to the corresponding cup independently of the corresponding ear or mouth piece, additional means being employed for securing the corresponding pieces 46 to their associated cells. The arrangement is such that each cup, in cooperation with its associated ear or mouth piece completely surrounds the associated cell and these two elements are locked against relative movement therebetween so when fully assembled. Each of the two means for respectively securing the ear and mouth pieces to their associated cells is constructed so that it alone-can be actuated to remove the piece or; member secured thereby. 'Ihese securing means ll working parts of the transmitter, and particularly the transmitter diaphragm, against moisture and dirt which normally enter through the sound transmission holes on apertures of the mouth. piece.

the holes in the mouth piece with respect to the holes in the front supporting member of thetransmitter cell so that no direct path exists between the mouth piece opening and the trans- -mitter diaphragm. The means for interconnect v ing the contact members ofthe 'two cups comprises conductors embedde'd in'the moulded handie, at least a portion ofwhich have insulating material thereon so that during the process of manufacture there is no possibility of electrical interconnection of these conductors.

The novel features believed to be characteristic of the invention are set forth with particularity in the appended claims. The invention itself, however; both as to its organization and method of operation, together with further objects and advantages thereof will best be understoodby reference to the specification taken in connection with the accompanying drawings, in which: Figure 1 is a cross-sectional view illustrating a telephone instrument of the hand set type having embodied therein the features of the present invention; Fig. 2 is a schematic view illustrating the manner of electrically interconnecting the various elements of the instrument;

Fig. 3 is an exploded view illustrating the details 'of the receiver and the mode of assembling the various elements thereof; Fig. 4 illustrates the details of the locking means embodied in the receiver assembly; Fig. 5 is an exploded view illustrating the elements of'the transmitter and their mode of assembly; and Figs. 6 to 9, inclusive, are bottom, top, and cross-sectional views respectively, illustrating the details of the receiver cell construction.

the drawings, there is shown a telephone instru- 'rnent of the hand set type havingembodied therein the various features of the invention as outlined above. In brief, the instrument comprises a handle Ill, having integral therewith the receiver and transmitter cups H and 12-, respectively, which partially house the receiver and transmittercells l3 and I4, respectively. Cooperating with the cups II and I2 completely to surround the cells l3 and I4 are ear and mouth pieces l5 and I3, respectively. The ear and mouth pieces or members l5 and I3 and the integral handle l0 and cups H and 12 are constructed of insulating material, preferably consisting of a phenol plastic compound such as Bakelitef. The

month piece or member It comprises a cupshaped portion which is adapted to engage at its outer edge the edge of the cup I 2, and is provided with spaced apart, sound transmission holes I! arranged to form a circle in the bottom portion of the 'cup in the manner illustrated.

The transmitter cell l4 may be of any desired type although preferably the moving parts there: of are constructed and arranged in the manner illustrated and described inapplicants co-pending application Serial No. 40,738, filed September 15, 1935. In brief, the cell comprises a pair of supporting members l8 and I9 preferably consisting of a light weight aluminum alloy, and are provided with interengaging threads 20 and 2| This is accomplished by offsetting Referring now more particularly to Fig. 1 of for assembling the cell. The member i8 is provided with spaced apart sound transmission holes or openings 22 which are arranged on a circle of smaller diameter than the circle of the holes H in the mouth piece It, the adjacent surfaces 23 and 24 of the members I8 and the mouth piece 16 being spaced apart by means of a thin washer 25- of softrubber or other suitable material, to

permit sound waves to travel through the two sets of openings l1 and 22 to the diaphragm of the 'cell. By offsetting the two sets of holes l1 and 22 in the manner described, dirt and moisture,

more particularly the latter passing through the outer set of openings II, are intercepted by the solid outer surface 23 of the member I8 and do not enter the openings 22 leading to the trans,- mitter diaphragm. Thus, the delicate-parts of the transmitters moving system are protected from foreign matter. As described in the above referred to co-pending application, the moving system of the transmitter cell ll comprises a conically-shaped main diaphragm 26 having a relatively wide flange around its outer edge which is clamped between adjacent surfaces of the supporting members 18 and I9 in the manner shown, and a secondary diaphragm 21 in the form of a conical ring having an opening in the center thereof. A dome-shaped cup "extends through this opening and is provided with a flange which overlaps the edge of the opening in. the secondary diaphragm 21 and, in conjunction with a rivet 29, holds the diaphragm assembly together. A ring-shaped electrode 30 constructed of carbon is fastened to the flanged portion of the cup 28 in any suitable manner to move therewith, and opposite this moving electrode there is provideda second carebon electrode 3| of the same shape which is rigidly mounted on a second dome-shaped cup 32. The latter cup is, in turn, rigidly fastened to the housing or supporting member I9 by means of a threaded ring as, being electrically insulated therefrom by means of ring-shaped insulating washers 34 and an insulating cylindrical ring 35. Between the adjacent. edges of the carbon ring electrodes 30 and 3| there is cemented a flexiblepaper bellows 36 of circular shape which ilar construction. However, the cell has certain operating advantages, resulting from the features described, which are designed to improve the frequency response characteristic and thereby to enhance the fidelity of transmission over the range of frequencies ordinarily encountered in audible conversation. Since the general mode of operation of a transmitter cell of-the general a type shown is well understood and the details of the moving system and-the operating features thereof form no part of the present invention,

a detailed description thereof is omitted in the interests of simplicity.

' In accordance with conventional practice, the contact members for terminating the cord conductors of the instrument are located at the transmitter end of the hand set and comprise metal inserts, two of which are shown at 38 and 38, partially embedded in the moulded Bakelite forming the cup l2. The insert 38 is connected by means of a spring contact piece- 40 to the contact member 31 which forms the plug for the cup 32. A third contact member in the form of an annular ring 4| threaded along its outer surface is partially embedded in the Bakelite forming the mouth of the cup I2 and is of such a diameter that the threads of the exposed portion thereof engage the threads 20 along the inner surface of the member l8 to secure the cell l4 in its mounted position.

The last-mentioned annular contact member 4| is connected by means of an insulated conductor 42 embedded in the handle I to a contact member 43 at the receiver end of the set, which member is connected through a contact spring 44 to one of the terminals of the receiver cell l3. The contact member 43, together with a second contact member 45 in the form of a cylindrical ring, are partially embedded in the Bakelite forming the bottom of the receiver cup II and the latter contact member is arranged to be connected to a second terminal of the receiver cell l3 by-means of a contact spring 46 mounted on'the bottom of the cell. A i

The receiver cell l3 comprises, in general, a pair of supporting members 41 and 48 preferably of a light weight non-magnetic conducting material such as an aluminum alloy, the former of which is provided with a cylindrical flange 49 threaded along its inner surface and the lat- .ter of which is in the form of a flanged cup having threads along the outer surface of the flange which are adapted to engage with the inner threads of the flange 49 to assemble ,the cell. Supported within the cup-shaped member 48 on the bottom thereof is the magnetic field structure indicated generally at 50. This structure includes field windings 53 and 54 individually wound on corresponding pole pieces in the manner described more in detail hereinafter. A thin diaphragm 5| is provided which is rigidly clamped to the upper edge of the flanged cupshaped member 48 by means comprising the member 41 and.a 'dished spring member 86, in the manner illustrated, and described in greater detail in a later portion of the specification. It will be noted that the threads along the inner surface of the flange 48 in addition to engaging the threads of the member 48 to-clamp the diaphragm 5| in place and complete the assembly of the cell I 3, engage the exposed threaded portion of an annular contact member 52 which is partially embedded in the Bakelite forming the mouth of the receiver cup H, thereby to secure the receiver cell in position within the cup independently of the ear piece l5.

Referring now more particularly to Fig. 2 of the drawings, there is illustrated in partially schematic form the manner of connecting the various contact members and circuit elements of the receiver and transmitter cells to form the complete hand set network of a substation circuit. The circuit corresponds to the antisidetone arrangement completely disclosed and described in the United States patent to Pye, No. 1,687,695, granted October 16, 1928. In coniormance with the arrangement disclosed in this patent, the two field windings 53 and 54 have a common terminal, comprising the contact member 43,-whlch is connected to one terminal of the transmitter through the conductor 42 and sulate the conductors one from the other.

the contact member 4|; and independent terminals connected to the contactmembers 45 and 52, respectively, which are 'terminated at the corresponding cord terminal contact members by means comprising a pair of conductors 55 and 56, respectively. As described in thepatent referred to above, the windings 53 and 54 are so proportioned relative to each other that they perform the functions of a receiver and an induction coil during the" reception and transmission of signals andalso form an artificial line and provide the necessary balance to secure the desired antiside-tone effect during the transmission intervals. The other contact members mounted within the transmitter cup l2 are properly connected to the terminals of the transmitter cell l4 and the various conductors of the hand set cord indicated at 51 in the manner illustrated.

As indicated above, the 'conventional method of interconnecting the various contact members is that of embedding or moulding the conductors such as 42, 55, and 56, in the handle l0 during the process of manufacture, bare conductors being used and the moulded insulating material of the handle alone being depended upon to in- This method is not entirely satisfactory for the reason that it is diflicult to maintain the conductors separated during the moulding operation and, consequently, there results a high percentage of failures or defective instruments.

In accordance with one feature of the present invention this difliculty is entirely obviated by temperatures necessarily involved in the mould-.

ing process. Although preferably all of the conductors are insulated in the manner shown, ade

quate protection against short-circuiting may be obtained if only a' portion thereof are so insulat-' ed. Thus, perfectly satisfactory insulation may be obtained if only two of the three enumerated conductors 42, 55 and 56 are insulated.

Referring now more particularly to Figs. 3 and 4 of the drawings, there is illustrated the method of assembling the various elements of the receiver, whereby the desirable feature of protecting this element of the hand set against unauthorized disassembly is obtained. This method comprises clamping the diaphragm 5| to the upper edge of the cupped supporting or housing member 48 by meansof the supporting member 41 and the dished spring 86, thereby to complete the, receiver cell assembly. Following this, the member 41 is screwed onto the'threaded ring 52 to secure the cell l3 in place within the receiver cup H and to bring the associated contact mem--* bers mounted on thecell and within the cup ll into flrm engagement. It is pointed out here l that the inner threads of the flange 49 engage the threaded portion of the member 48 and also in the manner described, the ear piece I5 is placed in position over the cell so that in cooperation with the cup II it completely surrounds the cell. This piece is mounted on the cell I3, and more particularly on the member 41 by means of a flanged cap 58 having threads 58 along the shank thereof which engage threads 60 provided along the edge or a circular opening cut in the member 41. This cap is also provided with a small hexagonal sound transmission opening 82 through which the sound produced by vibration of the diaphragm 5| may be transmitted 'to the ear of a listener. The flange provided on the cap 58 is adapted to rest against the bottom of a groove 6| out along the top edge of an opening in the ear piece I5 so that, when the cap is screwed into the member 41, the ear piece is firmly mounted on the cell l3.

As pointed out above, it is extremely desirable to provide an instrument wherein the transmitter and receiver elements cannot readily be disassembled by curious'and unskilled persons. Theconstruction 'of the cap 58 contributes to this result in that the top thereof is flush with the face of the ear piece I5 and the element can only be unscrewed from the member 41 to remove the ear piece by employing a special tool having a hexagonal end of the proper size snugly to engage the sides of the hexagonal opening 82. It is pointed out, however, that this arrangement is alone not totally effective to prevent removal or the ear piece I5 due to the fact that sufilcient friction exists between the engaging surfaces of this piece and the cap 58 to enable the cap 58 to be unscrewed suificiently to permit its removal without the use of a special tool of the form noted when the ear piece I5 is rotated relative to the receiver cup II. y

In accordance with a further feature of the present invention the dimculty as outlined in the preceding paragraph is obviated by providing means, in the form oi! inter-engaging locking means along the adjacent edges of the two' enumerated elements, for preventing such relative movement between the member I5 and the cup II. As shown more particularly in Fig. 4, this locldng means comprises spaced apart projections 83 interposed between grooves 84 along the inner edge of the ear piece I5 which cooperate with similar grooves 85 and projections 88 alternately spaced around the outer edge of the cup II. The interlocking action between the projections 63 and the grooves 85 prevents any substantial relative movement between the cup I I and the ear piece I5and thus positively pre-x vents the cap 58 from being loosened without using a tool of the special form described.=

As shown in Fig; 5, the method of assembling the elements of the transmitter is substantially similar to that described above in connection with the receiver assembly. Thus, the inner threads of the supporting member-l8 cooperate with the threads of both the supporting member I9 and theexposed threaded portion of the contact member 4| to perform the double function of completing the transmitter cell assembly and securely mounting this cell within the transmitter cup I! in such a position that each pair of associated contact members. of the cell and the cup are in firm engagement. As in the, case of the receiver assembly, the mouth piece I8 is provided with spacedapart grooves indicated at 81 cated at 68, along the upper edge of the cup I2, to prevent relative rotational movement between the mouth piece or member I8 and the cup I2. A slightly different means is provided, however, for mounting the mouth piece I8 on the transmitter cell I4. This means comprises a threaded stud 69 projecting outwardly from the supporting member l8, which stud is adapted to pass through an opening I0 in the bottom of the cupped portion of the mouth piece l6 and to have screwed thereon a cap H having a metal insert 12 provided with tapped threadsfor engaging the threads of the stud 69. This cap ll is of a diameter not greater than the diameter of the circle tangent to the sound transmission holes or openings I1 and, with the exception of grooves 13 provided at diametrically opposite points along its sides, is of a smooth rounded contour. The grooves 13 are adapted to be engaged by the prongs of a special tool employed for the purpose of screwing the cap tightly against the outer adjacent surface of the mouth piece I6. By this method of assembly the transmitter cannot readily be taken apart except by using a specialtool oi the form described and consequently this portion of the hand set is also protected against unauthorized disassembly.

From the foregoing description of the transmitter and receiver assemblies it will be apparent thatthe individual telephone instrumentcells, namely, the transmitter and the receiver cells, are mounted independently of the associated ear or mouth piece. Moreover the. mounting arrangement is of an extremely rugged character. It is pointed out further that the method of asseniibly obviates the use of Bakelite to Bakelite threads between the individual transmitter and receiver cups and their respective associated mouth and-ear pieces. Also, the latter pieces receive considerable support from the cells which they individually surround. Thus, the member 41 embodied in the receiver cell I3 fits snugly within the ear piece l5 so that the shock incident to a severe blow on the ear piece is largely absorbed-by the sturdier metal parts of the cell.

l3. For the same reason the supporting member I8 of the transmitter cell is constructed to fit snugly within the cup portion of the mouth piece l6. This additional-support for the walls of the pieces l5 and I8 permits the walls thereof to be made much thinner than is possible in these arrangements typical of the prior art.

Referring now to Figs. 6 to 9, inclusive, of the drawings, and more particularly to Figs. '7 and 8, there are illustrated the details of the receiver cell generally described above. As shown, the magnetic field structure comprises a pair of pole pieces 14 and 15 having pole faces 16 and II, respectively, adjacent to but separated from the diaphragms 5! by an air gap of suitable length. Individually mounted on the pole pieces 14 and 15 are the windings 53 ,and 54,'having terminiis (not shown) commonly connected to the contact spring 44 and individual terminals not shown individually connected to the member 48 and the contact spring 46. The enumerated contact members are insulated from each other by insulating washers l8 and 19. Each of the pole pieces 14 and 15 includes an outwardly extending fiang which is provided with a portion 80 ofi'set with respect to the plane passing through the axial centers of windings 53 and 54. Mounted on these ofiset portions 88 and included in the magnetic circuit of the field structure is a polarizing permanent magnet 8|. a

the cup-shaped supporting member 48 by means comprising a pair of screws 84 and 85 which extend through openings in the brackets 82 and 83 and in the pole pieces 14 and 15 and are threaded into the bottom portion of the mem-' ber 48.

It is advantageous to clamp rigidly with uniform force all points of the receiver cell diaphragm periphery and to stretch the diaphragm during the clamping operation, thereby to secure greater stiffness thereof. These results are attained by providing spring means in the form of a dished spring 86 which cooperates with the two members 48 and 41 to clamp the diaphragm 5| at its outer periphery against the upper edge of the cup-shaped member 48. This spring 86 rests in an outwardly tapering groove provided in the bottom of the cupped clamping member 41 and is so arranged that its outer edge projects beyond the outer edge of the groove to engage resiliently the adjacent surface of the diaphragm 5| during the clamping operation. Thus, as the member 41 is screwed onto the member 48 the extreme outer edge of the spring 86 comes in contact with the adjacent surface of the diaphragm 5| to exert a substantially uniform clamping pressure, on the periphery of the diaphragm at all points thereof.- Additional clamping pressure causes the outer peripheral edge of the dished spring to flatten with the result that it expands slightly in a radial direction and exerts a decided stretching forceon the diaphragm 5|. This force artificially enhances the stillness of the diaphragm with the resulting advantage of improving its frequency response character'- istic.

The arrangement for clamping uniformly the diaphragm to the associated supporting member and for stretching the diaphragm described above is disclosed and claimed in applicant's copending application, Serial No. 165,257,- filed September 23, 1937, which is a division of this application.

While there has been described what is at present considered to be the preferred embodiment of the invention it will be understood that various modifications may be made therein without departing from the invention audit is conof said. pieces associated therewith and in a position such that the associated contact members This difliculty is obviated by emare in firm engagement, and means for securing each of said pieces to its corresponding cup.

2. A telephone hand set comprising transmitter and receiver cups each including contact members, self-contained transmitter and receiver cells each including contact members for individually engaging the corresponding contact members of the corresponding cup, ear and mouth pieces associated with corresponding ones of said cells, means for securing each of said cells in assembled relation and in its corresponding cup independently of the corresponding one of said pieces associated therewith and in a position such that the associated contact members are in firm engagement, means for securing each of said pieces to its corresponding cup, said last-named means each including a member requiring a special tool to actuate the same to remove the corresponding piece but being incidentally actuatable when the corresponding piece is moved in one direction relative to the corresponding cup, and locking means for preventing such relative movement.

3. A telephone hand set comprising a cup constructed of insulating material, an annular member rigidly secured to said cup and having a por-- tion threaded along one of its peripheral edges, a telephone instrument cell comprising a pair of supporting members provided with interengaging threads for assembling said. cell, the threads of one of said last-named members engaging with the threads of said annular member to secure said cell to said cup, 2. member constructed of insulating material and provided with a cupped portion for surrounding the portion of said cell extending outside said cup, and means for securing said last-named member to said cell, said means comprising a threaded portion of one of-the supporting members of said cell and an additional member provided with threads engaging the threaded portion of said one of said cell members, said additional member being so constructed as to require a special tool for unscrewing the same to remove said member constructed of insulating material from the hand set assembly.

4. A telephone hand set comprising a cup constructed of insulating material, an annular member rigidly secured to said cup and having a portion threaded along one of its peripheral edges, a telephone instrument cell comprising a pair of supporting members provided with interengaging threads for assembling said cell, the threads of one of saidlast-named members engaging with the threads of said annular member to secure said cell to said cup, a member constructed of insulating material and provided with a cupped portion for surrounding the portion of said cell extending I outside said cup, means for securing said lastnamed member to said cell, said means comprisinga threaded portion of one of said supporting members of said cell and an additional member provided with threads engaging the threaded portion of said one of said cell members, said additional member being so constructed as to require a special tool for unscrewing the same to re move said member constructed of insulating ma terial from the hand set assembly, and means for preventing relative rotary movement between said cupand the member of insulating material,whereby said additional member is prevented from being unscrewed except through the use of said special tool.

' 5. A telephone instrument assembly compris l ing a cup constructed of insulating material, a

special tool for unscrewing the same to removesaid member constructed of insulating material from the telephone instrument assembly. I

6. ,A telephone instrument assembly comprising a cup constructed of insulating material, a tele-.

phone instrument c'ell rigidly mounted partially within said cup, a member constructed of insulating material and having a cupped portion surrounding-the portion of said cell extending outside said cup, means for securing said member to said cell, said means comprising a threaded portion of said cell and an additional member provided with threads engaging the threaded portion of said cell, said additional member being so constructed as to require a special tool for unscrewing the same to remove said member constructed of insulating material from the telephone instrument assembly, and means comprising interlocking portions of said cup and said member constructed of insulating material for preventing relative rotary movement between said cup and said member constructed of insulating material,

whereby said additional member is prevented from being unscrewed except through the use oi. said special tool.

mom 0. PYE.

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