US3560687A

US3560687A - Cross-string telephone employing pushbuttons

Info

Publication number: US3560687A
Application number: US724574A
Authority: US
Inventors: Josef Hofer; Guenter Haage
Original assignee: International Standard Electric Corp
Current assignee: Alcatel Lucent NV
Priority date: 1967-04-28
Filing date: 1968-04-26
Publication date: 1971-02-02
Anticipated expiration: 1988-02-02
Also published as: CH477752A; SE331118B; DK123447B; DE1762199A1; AT266970B; NL6805935A; ES353274A1; NO121287B

Abstract

A pushbutton is provided for use with cross-string conductors supported on a base plate. The elements of the pushbutton are made so that they may be assembled and attached to the board without the use of separate fasteners. Contact is completed between cross-string conductors on the base plate when a part of the push button, i.e., a V-shaped spring, touches them. The pushbutton incorporates a spring which biases it to a neutral position when it is not pressed against the conductors.

Description

United States Patent Inventors Josef l-loier;

(iuenter Haage, Wien, Austria Appl, No. 724,574 Filed Apr. 26, 1968 Patented Feb. 2, 1971 Assignee International Standard Electric Corporation New York, N.Y. a corporation of Delaware Priority Apr. 28, 1967 Austria 4065/67 CROSS-STRING TELEPHONE EMPLOYING PUSHBUTTONS 7 Claims, 1 Drawing Fig.

U.S. Cl 200/166, 179/158 Int. Cl H0lh 3/12 Field of Search 200/ 1 75,

[56] References Cited UNITED STATES PATENTS 2,587,458 2/1952 Fritts 200/l66( 1) 2,747,144 5/1956 Beers ...200/166(. 1 )(X) 3,051,799 8/1962 Paul et a1. ..200/166(.1)(X) 3,060,784 10/1962 Holt i ..200/166(.1)(X) 3,330,916 7/1967 Bauer ...200/l66(.1)(X) 3,392,250 7/1968 Ziegler et a1 ..200/166(. 1 )(X) Primary Examiner-H. 0. Jones AttorneysC. Cornell Remsen, Jr., Rayson P. Morris, Walter J. Baum, Percy P. Lantzy, 1. Warren Whitesel and Delbert P. Warner ABSTRACT: A pushbutton is provided for use with crossstring conductors supported on a base plate. The elements of the pushbutton are made so that they may be assembled and attached to the board without the use of separate fasteners. Contact is completed between cross-string conductors on the base plate when a part of the push button, i.e., a V-shaped spring, touches them. The pushbutton incorporates a spring which biases it to a neutral position when it is not pressed against the conductors.

PATENTEU FEB 215m I nuenlors Illa/"ER 6. #19065 YdQ W A tlorney CROSS-STRING TELEPHONE EMPLOYING PUSHBUTTONS The invention relates to a resilient electrical contacting device, such as is used in signalling installations, domestic bell systems and domestic telephone systems.

The resilient electric contacting device according to the invention consists of a movable contact carrier and a stationary contact carrier, which comprises at least two conductors; and is characterized in that the movable contact carrier comprises a flat base of plastics material, which has on one end a detachable key cap and on the other end a V-shaped wire spring, which is round or angular in cross section and has a tip adapted to snap into an aperture of the flat base whereas its limb is guided by ribs of the base, the base is provided at the other end with noses, which extend beyond the width of the flat base, the stationary contact carrier consists of a cup, which is countersunk in a plate and has slots for guiding the flat base, which slots have a window to the outside at the bottom of the cup, the resilient noses of the flat base snap into the window and are freely movable between the stops, a cylindrical compression spring is provided, which bears on the bottom of the cup and on shoulders of the flat base, and at least two wire springs are provided, which are round or angular in cross section and cross the V-shaped wire spring at right angles and are guided in grooves against yielding laterally, and in noses against lifting from the baseplate and yielding to one side, said wire spring terminating directly in clamping means.

In a development of the invention regarding the key head, one end of the flat base consists of crossing tabs, which are received in the cavity of the detachable key cap when the same is mounted, the flat base is guided in grooves in the cavity of the key cap, and noses of the flat base snap into recesses of the grooves in the cavity of the key cap and enable the key cap to snap in and to be held in position.

In a further embodiment of the regarding the key head, each key is provided with a digit or a symbol so that the wiring expenditure can be optimized by a free selection of the sequence of keys.

In a particularly advantageous, further development of the invention, the symbols consist of different colored keys.

According to the invention, the limbs of the V-shaped springs include a smaller angle at the apex of the V than at the ends of the limbs and the angle is changed continuously or in a step, e.g., approximately in the middle of the limbs.

In a further embodiment of the invention regarding the clamping device for holding the stationary contact members in position, the clamping device for directly holding the stationary contact spring wires at least at one end consists of rectangular insulating walls, which are at right angles to the base plate and are closed on three sides and serve for receiving a square nut, said walls have a through aperture for receiving the stationary contact wire springs, through apertures for the connecting bolts and apertures for receiving the lugs of the cover plate and a bolt are provided, and the ends of the fixed contact spring wires are bent, preferably curved, and are clamped by the screw between the cover plate and the nut and held in the base plate by the lugs.

Further according to the invention, the through aperture for the connecting bolts and the apertures for receiving the lugs of the cover plate form a single aperture.

Further according to the invention, the assembling opera tion can be facilitated in that the clamping devices are arranged in rows one beside the other and in steps on different levels. To facilitate the connection of plug joints, it is a feature of the invention that the cover plate has a short lug, which is to be passed through a corresponding aperture and to be reversely bent or pivotally moved, and an extended lug, which is to be passed through another aperture and for reverse by bent and passed out through a window in the step, and a plug joint is adapted to be connected to the extended lug.

In a preferred embodiment of the invention, the assembling of the flat base in the grooves of the cup is facilitated in that the ends of the grooves are beveled in the form of a roof.

Finally, the ribs provided in the flat base and serving to guide the V-shaped spring, may, in accordance with the invention, be extended substantially in the longitudinal direction of the flat base and form reinforcing ribs.

An illustrative embodil'nent of the invention will now be explained more fully with reference to the FIG.

The

limbs

53 and 54 of the V-shaped wire spring 3 serve to electrically connect the two conducting

wires

20 and 21 when the key cap 2 is depressed, where the cap 2 has been fitted on top of the flat base 1. The V-shaped wire spring 3 is snapped into the hole 4 with the apex of the spring directed toward the base plate 9. The spring 3 is guided against lateral movement by the

ribs

5 and ,6. The V-shaped wire spring 3 can move between the ribs Sand 6 at right angles to the flat base 1 and to the ribs. in position of rest, the V-shaped wire spring cannot contact either of the

conductors

20 and 21.

The base plate 9 contains the cup 10 having

slots

11 and 12. The spring 19 is first inserted into the cup 10, then the conductor 20 into the groove 22 and the nose 25, and the conduc' tor 21 into the

noses

24 and 26 and the groove 23.

The conductor ends 55 and 56 are gripped by the clamping device 27, 28 and the clamping device 38, respectively. The other ends are freely movable.

Provided with the V-shaped spring 3 and the key cap 2, the flat base 1 is now inserted into the space between the conducting

wires

20 and 21 with its

noses

7 and 8 entering

grooves

11 and 12. This operation is performed against the pressure of the spring bearing on the

shoulders

17 and 18, and is facilitated by the

rooflike bevels

57 and 58. The

noses

7 and 8 are bent inwardly toward the V-shaped wire spring and are then depressed into the

windows

13 and 14 and snap into the same.

The lower and

upper edges

15 and 16 of the window 13 and the corresponding edges of the window 14 cooperate with the

noses

7 and 8 to control the freedom of movement of the flat base 1. In a position of rest, the stress of the cylindrical compression spring 19 holds the base 1 in its upper position. When depressed, the base 1 is in its lower position against the stress of the cylindrical compression spring 19 but only as long as pressure is applied to the key cap 2.

The flat base can easily be removed. It is sufficient to hold the base in a somewhat oblique position and to urge the

resilient nose

7 or 8 through the window so that the base can be pulled out upwardly. In this condition the cylindrical spring 19 contacts preferably the

conductors

20 and 21.

The invention is not restricted to the use of only one resilient contacting device. A plurality of contacting devices can be arranged in the same plane as the flat base 1. ln such a case, the

conductors

20 and 21 must be correspondingly bent laterally. The conductor 20 may be the common return con ductor from all these contacting devices to a source of current.

The

clamping devices

27, 28 and 38 are an essential part of the device according to the invention. They are held in position due to the special fonn of the

ends

55 and 56 of the conducting

wires

20 and 21.

Each clamping device for locating the stationary contact members of the contacting device according to the invention consists of two rectangular insulating walls such as 27 and 28. These walls are at right angles to the base plate 9 and closed on three sides and serve to receive a square nut 33. These walls have a through opening 29 for the fixed contact spring wire 20 and a hole 30 is provided for receiving a connecting bolt 35. The square nut 33 is received in the rectangular space defined by the sidewall. Above the nut, there is the U-shaped end 55 of the conducting wire 20 and above the same the cover plate 34, which has

lugs

36 and 37, which are inserted into the

holes

31 and 32 and are held in position on the under side of the base plate 9 by being laterally bent or bonded. The bolt 35 urges the cover plate 34 and the nut 33 against each As the end 55 is clamped, the conductor 20 is inserted under the nose 25, the conductor 20 is inserted in the groove 22, and the resilient conducting wire is held in position. During the movement of the V-shaped contact spring 3, the conductor 20 can yield resiliently to some extent within the limits defined by the nose 25 and the groove 22.

ln a preferred embodiment of the invention, the clamping devices are arranged one beside the other. In a further preferred embodiment of the invention, such rows are arranged in steps so that the connection to equipment and leads outside the equipment can be established easily and in a clear arrangement.

The drawing shows the clamping device 38, which is disposed on a level below the clamping device 27, 28. The end of the conductor 21 is correspondingly offset and is guided, e.g., in a separate groove on the left on the sidewall 27 (not shown). The sidewall 27 may be a part of this groove. The components of the clamping device 38 are the same as those of the clamping device 27, 28.

In a further embodiment of the invention, one lug of the cover plate is extended, such as the lug 61 in the drawing. The lug 61 is inserted through the slot 63 and moved out at the forward edge of the parallel to the base plate 9. A plug may be fitted on this extended lug to receive a detachable connection.

When the conducting wire 21 has been installed, it can also yield resiliently to the outside when the keys are depressed. This yielding is limited by the groove 23 and the

noses

24 and 26.

The grooves and 6 may be extended to form

ribs

64 and 65 in order to improve the stiffness of the flat base 1.

The key caps 2 are removable,

Ribs

43, 44, 45, 46 inside the key cap cooperate with recesses 48 and corresponding noses 47 to hold the key caps in position. The

ribs

39 and 40 serve for stiffening and for a straight guidance of the key cap on the flat base 1.

In the previously known contacting devices, such as in domestic telephone systems, stationary key heads, which were connected to the bases of the movable contact carriers, were always used and were provided with consecutive numbers. As a result, four such keys enabled the provision of only four numbers. In such circuit the calling station must be included in those numbers. As there are only numbers 1 to 4 in each station, different telephone directories had to be used for each station as each number was not associated with one and the same station in each station.

An important advance toward unification has been ea established'by the provision of detachable key caps and the supply of one additional number (e.g., the supply of key caps 1 to 5 with four keys). In a modification of this invention, colored key elements rather than digits are used and only one color is associated with each station.

The resilient electrical contacting device according to the invention has the advantage that there is a considerable saving in costs due to the reduction in the number of conventional parts and in assembling time. The tolerances of the components may be very large so that an industrial mass production at low cost is enabled.

The fact that the contact wires are resilient and the arrangement of the crossing wires according to the invention results in a self-cleaning of the contacts. The provision of the crossing points avoids a soiling of the contacts.

It is generally sufficient to guide the flat base 1 in the

grooves

11 and 12. If a cap having apertures for the key head is disposed over the base plate, these apertures will assist the guidance of the movable contact carrier.

While the principles of the invention have been described above in connection with specific apparatus and applications, it is to be understood that this description is made only by way of example and not as a limitation on the scope of the invention.

We claim:

1. A resilient electrical contacting device comprising a movable contact carrier, a stationary fixed contact carrier, and two conductors, said movable contact carrier including a flat base of plastic material, said flat base having mounted on one end a detachable key cap and on the other end a V-shaped wire spring, said V-shaped wire spring having a tip adapted to snap into an aperture of the flat base and limbs guided by ribs of the flat base, the flat base including at the other end two noses which protrude beyond the width of the flat base. the stationary contact carrier including a cup which is countersunk in a flat plate and has slots for guiding the flat base, said slots having windows toward the outside at the bottom of the cup, the noses of the flat base snapping into said slots and being movable between stops at the ends of said slots, a cylindrical compression spring bearing on the bottom of the cup and on shoulders of the flat base, said two conductors including two wire springs which cross the V-shaped wire spring at right angles and are guided in grooves in the stationary contact carrier against yielding laterally, and noses which guard the two wire springs against lifting from the stationary contact carrier and yielding to one side, said two wire springs terminating directly in clamping devices.

2. A contacting device according to claim 1, in which one end of the flat base consists of crossing tabs, which are received in a cavity of the detachable key cap when the same is mounted, the detachable key cap including ribs forming grooves for guiding the crossing tabs, and noses forming part of the flat base snapping into recesses in the grooves in the cavity of the detachable key cap to enable the detachable key cap to snap in and to be held in position.

3. A contacting device according to claim 1, in which the limbs of the V-shaped wire spring are essentially parallel near the apex of the V and diverge beyond bends near the middle of the limbs.

4. A contacting device according to claim 1, in which the clamping devices for directly holding the two wire springs at one end include rectangular insulating walls at right angles to the stationary contact carrier which are closed on three sides and serve to receive a square nut, apertures in said walls to accept the two wire springs, apertures for receiving connecting bolts, and apertures for receiving lugs of a cover plate, and the ends of the two wire springs are bent and are clamped by the connecting bolts between the cover plate and the nut and held in the flat plate by the lugs.

5. A contacting device according to claim 4, including a cover plate having a short lug which is to be passed through an aperture and reversely bent, and an extended lug which is to be passed through another aperture and reversely bent.

6. A contacting device according to claim 1, in which the assembling of the flat base in the grooves of the cup is facilitated in that the ends of the slots are provided with rooflike bevels.

7. A contacting device according to claim 1, in which the ribs in the flat base are extended substantially in the longitudinal direction of the flat base to guide the V-shapcd wire spring and to form reinforcing ribs.

Claims

1. A resilient electrical contacting device comprising a movable contact carrier, a stationary fixed contact carrier, and two conductors, said movable contact carrier including a flat base of plastic material, said flat base having mounted on one end a detachable key cap and on the other end a V-shaped wire spring, said V-shaped wire spring having a tip adapted to snap into an aperture of the flat base and limbs guided by ribs of the flat base, the flat base including at the other end two noses which protrude beyond the width of the flat base, the stationary contact carrier including a cup which is countersunk in a flat plate and has slots for guiding the flat base, said slots having windows toward the outside at the bottom of the cup, the noses of the flat base snapping into said slots and being movable between stops at the ends of said slots, a cylindrical compression spring bearing on the bottom of the cup and on shoulders of the flat base, said two conductors including two wire springs which cross the V-shaped wire spring at right angles and are guided in grooves in the stationary contact carrier against yielding laterally, and noses which guard the two wire springs against lifting from the stationary contact carrier and yielding to one side, said two wire springs terminating directly in clamping devices.

7. A contacting device according to claim 1, in which the ribs in the flat base are extended substantially in the longitudinal direction of the flat base to guide the V-shaped wire spring and to form reinforcing ribs.