US2223926A - Automatic reset switch - Google Patents

Description

'Dem 3; 1940. H; R WARNKE 2,223,926

AUTOMATIC RESET SWITCH Filed May 23, 1939 2 Sheets-Sheet 2 i @MMM Patented Dec. 3, 1940 UNITED STATES AUTOMATIC RESET SWITCH Herbert R. Warnke, East Orange, N. J., assignor to United States Instrument Corporation, East Orange, N. J., a corporation of New Jersey Application May'23, 1933, Serial No. 275,281 claims. (ci. 179-38)l This invention relates to telephone systems of the direct connected type, i. e., systems in which no central switchboard is employed, connection between the calling station and the desired sta- 5 tion being made by means of a switching mechanism located at the calling station. More particularly, the present invention relates to an improvement in the circuits and mechanism employed in such systems, and especially those l0 adapted for selective ringing and selective talking, rather than those systems in which the ringing circuits and/or talking circuits of all stations on the system are constantly interconnected.

In the usual selective ringing and talking system of the type in question, each station is provided with a manually operated selective switch-4 ing device, usually in the form of a ro-tary dial switch. According to the common mode of installing such systems, the talking circuit between any two stations necessarily includes the selector switch at each station, so that the selector switch at each station must be turned to its home position in order to close the talking circuit between the two stations. In order to be in condition to receive incoming calls, therefore, it is necessary that the selector switch at each station be returned to its home position after each outgoing call. This is usually accomplished by providing a selector switch of the spring return type,

in which spring means are employed for returning the switch to its home position after each outgoing call. i

The system just described possesses several important disadvantages. One such disadvantage is the excessive cost of the spring return type of selector switch,` which mustbe of a very precise and expensive construction. Another disadvantage lies in the fact that the switch points of such selector switchesare subjected to excessive wear, due to the fact that the switch must be returned toits home position after each outgoing call, wiping all of the intervening contact points in the course of its travel. A fur-ther disadvantage lies in the fact that the rotating switch arms of such a selector switch can make only a light contact with the station-ary points, in'order that a return spring of convenient size may have sufcient power to perform its function.

These disadvantages may be overcome byl using, in place of the spring return selector switch, a selector switch which is manually operated in both directions but, unless the features of the present invention are employed inconnection with such manually `operated selector switch, the latter must be returned to the home position, by hand, after each outgoing. call, which is inconvenient and undesirable. x

This disadvantage of the manual return selector switch may in turn be overcome by providing conductors, which may be called home 5 lines, by-passingthe 4selector switch for the purpose of `establishing a talking circuit for incoming calls. By this arrangement the station is enabled to receiveincoming calls while the selector switch is set for connection to 10 another station, but in this case such other station is also connected in the talking circuit, which is undesirable for obvious reasons. Because of the foregoing disadvantages of the manual return selector switch, therefore, it has 15 been the usual practice to provide the spring return selector switchesrst described above.

It is the general object of the present invention to overcome the objections and disadvantages set forthabove and to provide means whereby a :20 manual selector 'switchmay be emp1oyed,with out provision for automatic return to home position, while at the same time avoiding the necessity of manually returning the selector switch to homeposition in order to receive incoming calls, ,25 the talking circuit between the home station and the station for which the selector switch is set being Y automatically maintained open except when it is `closed at the desire of a Vperson calling fromthe particular station which is regarded, for this purpose, as the home station. HA 4furtl'ierobject is the provision of means whereby, when the calling party has established a talking circuit between his home station and the called station, such talking circuit is auto- 35 matically vbroken when the call is completed, without the necessity of actuating the selector switch for this/purpose, and whereby said talking circuit is'maintained open until it is again closed at the desire of a person making a call. 40

Other and further objects, features and advantages of the present invention will be apparent to one skilled in the art from the following description taken in connection with the accompanying drawings in which: *45 `Figure 1 is a front elevation of a telephone instrument constructed in accordance with the present invention;

Figure 2 is a partial view of the instrument of Figur-e 1, withA the front oi the base portion cut 50 away to illustrate the internal mechanism;

Figure 3 is a'view` similar to Figure 2 but with aportion of the internal `mechanism cut away to better illustra-te the novel mechanism of the present invention; 55

Figure 4 is a View similar to Figure 3 illustrating the contact device in ringing position;

Figure 5 is a view similar to Figures 3 and 4 illustrating the contact device in talking position;

Figure 6 is a bottom view of the contact device of Figures 2-5.

Figure 7 is an end elevation of the contact device; and

Figure 8 is a circuit diagram showing the connections between two stations of the intercommunicating system, and illustrating diagrammatically the selector switch and contact mechanism associated with each station.

In order to facilitate an understanding of the invention, reference is made to the embodiment thereof shown in the accompanying drawings and detailed descriptive language is employed. It will nevertheless be understood that no limitation of the invention is thereby intended and that various changes and alterations are contemplated such as would ordinarily occur to one skilled in the art to which the invention relates.

Referring to Figure 1 it will be seen that the telephone instrument proper comprises a base I0 and a hand set which latter comprises a transmitter l2 and receiver I3 connected by a handle portion I4. The upper portion of the base l0 is provided with upstanding projections I5 forming a cradle for the reception of the handle portion of the hand set when the latter is not in use. In the present embodiment, the instrument illustrated is -of the modern design now in common use, but it will be understood that the present invention is capable of application to other types of instruments, in which a hand set of the present type is supported by a wall box or in which a separate receiver is supported on or from a base containing a transmitter. In the appended claims, the expression hand set is not intended to define a set comprising both receiver and transmitter, but refers broadly to that portion of the instrument which is lifted from the base when a call is made. I

The base III is provided with a selector switch comprising a dial I6, pointer I1 and bi-polar rotary contacting mechanism of conventional character (not illustrated) which latter lies within the base. In the present instance, the system is adapted to include 11 stations, and each numeral on the dial I6 indicates the position to which the pointer I1 should be set in order to connect the home station with on-e of the stations numbered in accordance with the dial. In Figure l the position of the pointer I1 indicates that the selector switch has been set so as to place the home station into communication with station No. 3. For the purposes of the following description, station I will be considered the home station, but it will be understood that each of the eleven stations is a home station from the standpoint of the person using the instrument at that station, and the -equipment'at each station is the same.

Figure 8 illustrates diagrammatically the circuits and connections between station |r and station 3, it being understood that the remaining stations are connected into the system in the same manner In interconnecting 'the eleven stations, for selective talking and ringing, it is necessary to employ twelve pairs of conductors, the eleven pairs of talking conductors being identiiied by the reference character I',

|"|I, Il", inclusive, each pair of such conductors being connected to like numbered terminals of each selector switch. The twelfth pair of conductors I8', I8" are connected to the respective terminals of a dry cell I9 or other suitable source of power for ringing purposes, the conductor I8" being connected by conductors 20, 20', etc., tothe bells or annunciators at the respective stations, and the conductor I8 being connected by conductors 2|, 2|', etc., to the contact blade 49 at each station. Since the equipment at each station is the same, only one station (station I) will be dealt with in the following description.

Referring to the left hand portion of Figure 8, it will be seen that the respective arms 23, 24 of the selector switch have been rotated to a position establishing contact with conductors 25 and 26 respectively, which in turn connect with conductors 3" and 3' respectively, and it is assumed that a person at station I desires to communicate with station 3, represented in the right hand portion of Figure 8. Before describing how such communication is effected, however, it will be desirable to describe in detail the contacting mechanism illustrated in Figures 2 7, and shown diagrammatically near the top of Figure 8.

Within the upper portion of the hollow base I0, and secured thereto in any suitable manner, there is provided a switch plate 30 which serves as a support for the contacting mechanism to be described. A bridge member 3| spaced from the switch plate 3!) by posts 32 and 33, lies against the upper inner surface of the base IIJ. The switch plate 38, bridge member 3l and upper horizontal portion 34 of the base I0 are suitably apertured to receive and guide the buttons or plungers 35 and 36, which are slidably mounted in said members, and are retained in place by means of pins 31 and 38, which also serve to limit the downward movements of the plungers 35 and 35. The plunger 3S is cylindrical throughout except for a projecting flange 39 formed at the lower -end thereof to limit the upward movement of the plunger. The plunger 35 as best seen in Figures 3-5 is somewhat longer than the plunger 36, and is formed with a collar 48, reduced neck portion 4|, and head portion 42, the collar 40 and the head portion 42 defining the sides of an annular recess therebetween.

Secured to the underside of the switch plate 3l) are two sets of contact members, seen in plan in Figure 6. One set, comprising the Contact blades 43, 44 and 45 is adapted to be controlled by the plunger 35 (Figure 2), and are suitably spaced from each other and from the switch plate 30 by insulating washers 46. The upper blade 43 of this set is provided with a contact point 43 which is adapted under certain circumstances to contact with a corresponding point 44 on the blade 44. A contact point 44 is adapted to engage a contact point 45 on the blade 45. The several blades are formed of resilient material, and the blade 44 is initially biased toward the blade 43, and constantly urges the plunger 36 upwardly.

The other set of contact blades, comprising the blades 41, 48 and 49 (Figure 3) is similarly but oppositely mounted under the switch plate 35, and is adapted to be controlled by the plunger 35. Contact point 41' on blade 41 is adapted to engage contact point 48' on blade 48,'while Contact point 48 on the underside of blade 48 is adapted to engage contact point ,49" on blade 49. Blade 48 is biased toward blade 41 and urges the plunger 35 upwardly at all` times.

The plungers 35 and 36 are so arrangedl and proportioned that When the hand set is resting in the cradle, it engages the upper'ends of the plungers and maintains them in the position illustrated in Figures 2 and 3, wherein contact points 44" and 45' are engaged, the contact blade 44 being somewhat depressed for this purpose. The corresponding blade 48' of the other set, however, is maintained in intermediate position so that none of the contact points in this set are engaged.i The several contact blades of each set are connected into the system asillus trated diagrammatically in Figure 8.

A bracket 59 is secured to the underside of the switch plate 30 adjacent the plunger 35 and carries a pivotally mounted latch member 5| which latter is provided with a nose 52 for engaging the annular recess between the collar 40 and head 42 of the plunger 35.' The counter clockwise movement of the latch member 5| is limited by engagement between the shoulder 53 formed thereon, and the underside of the switch plate 30, but the latch member 5| is free to make a considerable movement in theclockwise direction. The latch member 5| may be considered as generally triangular in shape, with the apex 54 pointing downwardly. Secured to the underside of the bracket 50 is a flat spring 55 having a button or protuberance 56 arranged thereon so as to engage the latch member 5| on one side or the other of the apex 54 and resist movement of the latch member. A small plunger 51 rests upon the end of the latch member opposite the nose 52, and extends upwardly through a suitable aperture in the top of the base I0, the plunger 51 being so arranged and proportioned that, when the hand set is resting in the cradle, the plunger 51 is depressed as shown in Figures 2 and 3, causing the latch member 5| to occupy the position shown inthose iigures.

When the hand set is lifted from the cradle, the plunger 36 is free to rise, breaking the engagement between the Contact points 44" and 45', and establishing contact between the points 43' and 44'. The plunger 35, however, cannot rise because of the engagement between its head portion 42 and the nose 52 of the latch member 5|. If the plunger 35 is now depressed, manually, to close the ringing circuit as hereinafter described, the apex of the latch member is forced past the protuberance 56 on the spring 55, and the latch assumes the position shown in Figure 4. raising the plunger 51 and disengaging the nose 52 of the latch member from the annular recess of the plunger 35. The plunger 35 is then free to rise to the position illustrated in Figure 5, in which contact points 41' and 48' are engaged, establishing a talking circuit. When the hand set is again replaced in the cradle, the plungers 35 and 36 will be depressed to the position shown in Figures 2 and 3, and the plunger 51 will also be depressed, forcing the apex 54 of the latch member past the protuberance 56 and bringing the latch member into the position shown in Figures 2 and 3.

Referring now to Figure 8 and assuming that station at the left side of the figure, desires to call station 3, at the right side of the figure, the hand set 4 is lifted from the cradle which permits the plunger 36 to rise and the contact point 44 to engage point 43. Plunger 35 is then depressed manually to bring contact point 48" into engagement withpoint 49'; The selector switch having previously been set in the position illustrated, it will be seen that a circuit has now been established from contact point 48'. through contact point 49', contact blade 49, conductor 2|, conductor I8', dry cell I9, conductors I8" and 26' to the bell 60 of station 3. Since the hand set at station 3 is resting inthe cradle, the contact points 44" and 45' of that station are in engagement, and the `ringing circuit is thus completed through conductors 6|', contact blade 45 of station 3, contact points and 44", contact `blade 44, conductors 62', 25", 3", 25, switch arm 23 of station conductor 63 and contact blade 48 to contact point 49". Accordingly, thebell 6|] at station 3 is energized.

When the pressure is removed from the plunger 35, the contact blade 48.1noves upwardly bringing the contact points 48 and 41 together. Similarly, when the hand set of station 3 is lifted the contact points 44"and 43' are engaged, and a talking circuit is established from the hand set I4 of station through conductor 64, contact blade 41, contact points 41', 48', conductor 63, switch arm 23, conductors 25, 3", 25', 62', contact blade 44, contact points 43', v44', contact blade 43, conductors 65', 64',-hand set |4' of station 3, conductors 65', 61', 26', 3', and 26, switch arm 24 and conductor 65 back to hand set I4 of station No. It will be noted that the aforesaid talking circuit has been completed irrespective of the position of the switch arms 23', 24 of station 43v` by virtue ofthe conductor 61', which is constantly connected between the rst terminal #3 of the selector switch and the common terminal thereof, and the conductor 62' which is constantly connected between the other terminal #3 of the selector switch and the contact blade 44.

The conductors 61 and 62' may be designated as home lines, since they permit the reception of incoming calls regardless of the positionof the switch arms of the selector switch at the called station.

When the callis completed, the hand sets of the respective stations are simply replaced in their cradles, and when this is done, the contact blade 48 at each station assumes an intermediate position, breaking the talking circuit through the selector switch at the calling station, and also at the called station if a talking circuit has been established through the selector switch at such station. At the same time, the latch 5| is forced into engagement with the plunger 35 at each station, and serves to maintain the contact blade 48 in intermediate position until another call originates at the particular station, necessitating the depression of the plunger 35 for ringing purposes. Thus, if the selector switch at station remains in the position to which it was set for calling station 3, and another station calls station I, the call can be received over the home lines 61 and 62, and station 3 will not be connected into the talking circuit for the reason that the circuit to that station is interrupted at 48", 49'.

From the foregoing description it will be apparent that the present invention overcomes the disadvantages and achieves the objects set forth above, and provides a simple, economical and efiicient instrument and system for the purposes set forth.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. In a telephone system of the direct connected selective ringing and talking type, a plurality of stations directly connected by conductors, a telephone instrument at each said station, said instrument comprising a hand set and a base, a manually operated selector switch at each station for selecting Ithe station to be communicated with, said selector switch being adapted to establish both a ringing and a talking circuit between said stations, manually operable means apart from said selector switch for closing said ringing circuit through said selector switch at the calling station, automatic means for closing said talking circuit through said select-or switch at the calling station when said ringing circuit is interrupted, conductors by-passing said selector switch at each station for establishing a talking circuit with a calling' station, ir-respective of the position of said selector switch, when said hand set is lifted at the called station, and automatic means at each station for maintaining the talking circuit through said selector switch open except during a call which has been instituted from the particular station, whereby a private two-way conversation rnay be had between two stations regardless of the position of the selector switch at the called station.

2. The combination defined in claim 1, said means for closing said circuits through said selector switch at the calling station comprising a resilient contact member adapted alternatively to close said circuits and biased so as to tend to close said talking circuit, and said last named means in claim 1 comprising -a latch member adapted normally to maintain said resilient member in an intermediate position, means for holding said latch member out of operation after said ringing circuit has been forcibly closed, and means for vautomatically resetting said latch member when the hand set is replaced on its base. I

3. A telephone instrument comprising a hand set and a base, said base having a cradle for receiving said hand set when the latter is not in use, a plurality of conductors within said base comprising portions of a ringing circuit and a ltalking circuit, a resilient contact member adapted alternatively to move upwardly to close said talking circuit Iand downwardly to close said ringing circuit and biased so as to tend to close said talking circuit, a plunger adapted to be actuated when said hand set is replaced in said cradle, said plunger being arranged and proportioned to restrain said resilient member in an intermediate `position, whereby both said circuits are open,

when said hand set is resting in said cradle, a movable latch member normally engaging said plunger and preventing upward movement thereof when said hand set is lifted, said latch member being adapted to permit downward movement of said plunger and to move to a disengaged position when said plunger is depressed, means for holding said latch member in disengaged position during a conversation, and means for resetting said latch member in engagement with said plunger when the hand set is replaced in the cradle.

4. The device defined in claim 3, said latch member being supported for swinging movement into and out of engagement with said plunger and said resetting means comprising a second plunger engaging said latch member and adapted to be actuated when said hand set is replaced in said cradle.

5. A telephone instrument comprising a hand set and a base, said base having a cradle for receiving said hand setwhen the latter is not in use, a plurality of conductors within said base comprising portions of a ringing circuit and a talking circuit, a contact member adapted alternatively to close said circuits, means for holding said contact member in intermediate position when said hand set is in said cradle, means for moving said contact member to close said ringing circuit, latch means normally preventing said ycontact member from closing said .talking circuit, rsaid latch means being adapted to permit such movement after the hand set has been lifted and the ringing circuit once closed, and means for resetting said latch in position to prevent closing of said talking circuit.

HERBERT R. WARNKE.

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