Nodally operated push-button switch

Abstract

A snap-action operable push-button switch has a metal contact of rectangular shape having a pair of rectangular holes at both sides of a central stripe integrally formed therewith, the central stripe being bent toward one side thereof and the metal contact also having a pair of rectangular resilient contact pieces integrally extended therefrom in a size smaller than the size of the rectangular holes.

Description

BACKGROUND OF THE INVENTION

This invention relates to a snap-action (nodally) operable push-button switch used for terminal equipment of electronic device.

It is an objective of the present invention to provide a snap-action operable push-button switch having improved electric characteristics; improved contacting sensitivity, and permitting rapid assembly for high productivity of the siwtch.

It is another objective of the present invention to provide a snap-action operable push-button switch which makes point contact with stationary contacts on a printed circuit substrate and may also positively separate therefrom.

It is a further objective of the present invention to provide a snap-action operable push-button switch which may make contact softly and may also provide sufficient play for knob (push-button) movement.

It is still another objective of the present invention to provide a snap-action operable push-button switch which may simplify the assembling process, reduce the number of wiring parts, and to simplify the wiring process so as to economically assemble small electronic computers such as desk or hand electronic calculators.

It is still another objective of the present invention to provide an operable push-button switch which is advantageous for producing the push-buttons in relatively small numbers and with various types of buttons.

SUMMARY OF THE INVENTION

According to the present invention, the operable push-button switch, as one aspect, comprises a plurality of operating units mounted in a frame. Each unit has a sliding lever (not a pivoting lever), a flexible conductive contacting plate with resilient contact pieces, an insulating plate, a coil spring, and a case for enclosing the aforesaid parts to form a multi-key push-button assembly. The contacting plate includes a bent potion (a center strip) formed at the center and bent reversely upon depression and also including resilient contact pieces formed integrally with the bent portion thereby providing a snap action or toggle like (nodal) operation.

These and other objects, features, and advantages of the push-button switch according to the present invention will become more fully apparent from the following description taken in conjunction with the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a top plane view of the assembly of the snap-action push-button switch of the invention;

FIG. 1B is an enlarged sectional view of the switch taken along the line IB--IB in FIG. 1A.

FIG. 2 is a perspective exploded view of the essential parts of the switch of the invention;

FIG. 3A is a perspective view, partly broken away, of the back of the frame;

FIG. 3B is a perspective view of the back of the case of the switch, partly cut out;

FIG. 3C is a perspective view of the back of the lever, partly cut out of the switch;

FIG. 4 is a side sectional view of the operating unit of the switch of the present invention;

FIG. 5 is an enlarged side sectional view, in the engaged state, of the knob and the lever of the switch of the present invention;

FIGS. 6A and 6B are enlarged perspective views of the flexible contacting plate, in two steps of its manufacture;

FIGS. 7A to 7C are explanatory views of the operation of the flexible contacting plate which deforms at the central stripe thereof upon depression. Wherein FIG. 7A shows the state of the contacting plate before it has been deformed, FIG. 7B shows the state of the contacting plate deforming upon the switch is closed, and FIG. 7C shows the state of the contacting plate mostly deformed; and

FIG. 8 is a side sectional view of the essential part of another embodiment of the switch using a rubber resilient spring instead of the coil spring of the prior embodiment.

Referring now to the drawings, numeral 1 indicates knobs (push-buttons), 2 a frame and 3 an operating unit. The operating unit 3 includes a case 4, a sliding lever 5, a coil spring 6, a flexible conductive contacting plate 7, and an insulating plate 8. Numeral 9 is a printed circuit substrate, and 10 are screws for mounting the printed circuit substrate 9 to the frame 2.

The snap-action nodally operable push-button of the present invention comprises one frame 2, one printed circuit substrate, and plurality of operating units 3 (composed as above) and a plurality of knobs to form a multi-key push-button assembly.

The knobs (push-buttons) 1 are made of synthetic plastic resin, and, as shown in FIG. 5, have an integral cylindrical mounting shaft 11 engaged into a hole 24 of the lever 5 at the lower center thereof. Each shaft 11 has integral projections 12, 12 which oppositely project from both sides of the end of the shaft 11 so that the knob 1 and the lever 5 are held together. The root portion 13 of the shaft 11 is tapered.

As shown in FIG. 2, the frame 2 is made of synthetic plastic resin, and has plural rectangular holes 14 aligned in a manner crossing at right angles for slidably engaging the levers 5. The frame 2 also has corresponding rectangular holes 15 (see FIG. 3A) formed stepwise to the holes 14 on the back of the frame 2 for engaging the rectangular cases 4. Each of the cases 4 (see FIG. 4) includes a small-sized rectangular portion 18 and large-sized rectangular portion 19. The frame 2 has a plurality of thread holes 17 to receive the screws 10 for mounting the printed circuit to the frame 2, at its peripheral edge and intermediate portion.

The cases 4 of the operating units 3 are made of synthetic plastic resin. Each case 4 has a small-sized hollow rectangular portion 18 and large-sized hollow rectangular portion 19 integrally formed therewith, and step 16 formed between the rectangular portions 18 and 19. As shown in FIG. 4, the lever 5 is slidably engaged with the inner wall of the small-sized hollow rectangular portion 18. The outer walls of the small-sized and large-sized hollow rectangular portions 18 and 19 are engaged with the holes 15 of the frame 2, respectively.

As shown in FIG. 3B a seat 20 is formed at the lower edge of the large-sized hollow rectangular portion 19 for mounting the movable contacting plate 7 to the insulating plate 8. Projections 21 are provided at the respective corners of the seat 20 for fixing the movable contacting plate 7 and the insulating plate 8. Legs 22 are projected at the opposite surfaces of the large-sized hollow rectangular portions 19 for securing the case 4 to the printed circuit substrate 9, and claws 23 are integrally projected from the end of the legs 22, respectively outwardly. The legs 22 are resilient, and when the legs 22 are inserted into the rectangular holes 36 formed at the printed circuit substrate 9 under pressure, the claws 23 of the legs 22 are engaged with the edges of the rectangular holes 36 so that the cases 4 are secured to the printed circuit substrate 9.

As shown in FIG. 3C, the sliding lever 5 is made of synthetic plastic resin and has a hole 24 formed at its upper central portion thereof for engaging the shaft 11 of the knob 1 and the projections 12. Lever 5 has a hole 25 for holding coil spring 6, the hole 25 being of a larger diameter than the hole 24 at the lower portion thereof, and a step 26 being formed between the hole 24 and 25. Stoppers 27 are formed at the lower portion of the lever 5 for preventing the lever 5, after having been inserted into the case 4, from being discharged out. The stoppers 27 are in contact with the step 16 of the case 4. The coil spring 6 is inserted into the hole 25 of the lever 5 in a manner that one end thereof is engaged with the step 26 and the other end thereof is contacted with the center of the movable contacting plate 7 to urge the movable contacting plate 7 and also to return the lever 5. The lever 5 slides within an opening and is not a pivoting lever.

The flexible conductive contacting plate 7 is, for example, made of phosphorus bronze thin metal plate having electroconductivity and resiliency. The plate 7 is punched, in the shape as shown in FIG. 6A, in such a manner that a pair of rectangular holes are formed at both sides of central stripe 28. The stripe 28 is integrally formed with the plate and a pair of rectangular resilient contact pieces 30 are integrally extended from the vicinity of the center of the stripe 28 in a size, and a shape, smaller than the size of the holes. Both side edges 29 of the plate 7 are parallel with the central stripe 28 and are drawn (or formed with any alternative process) into a bump so as to shorten the side edges compared to the central stripe 28 as shown in FIG. 6B. The central stripe 28 is bent with the result that the resilient contact pieces 30 extend from the central stripe 28. The contact pieces change direction relative to the curve of the central stripe 28, i.e. they are tangential to the curve. The contact points 31, provided at the ends of the resilient contact pieces 30 are bent to the other side, (downwardly as seen in FIG. 6B). When the center of the bent portion of central stripe 28 is depressed, the bent portion is reversely bent (see FIG. 7B) and when the depression is released, the bent portion returns to the original bent state by the resiliency of the center stripe 28. There are provided holes 32 at the respective four corners of the movable contacting plate 7 for engaging (fitting upon) with the projections 21 of the case 4.

The insulating plate 8 is made of synthetic plastic resin film, and is sized to meet the size of the seat 20 of the case 4. There are provided holes 33 at the respective corners of the rectangular insulating plate 8 for engaging with the projections 21 of the case 4. There are also formed rectangular holes 34 in the insulating plate 8 for inserting the free ends of the resilient contact pieces 30, respectively. The rectangular holes 34 also enable the contact points 31 (at the ends of the resilient contact pieces 30) to make contact with the stationary contacts 35 of the printed circuit substrate 9. The insulating plate 8 insulates (other than its holes 34) the movable contacting plate 7 from the printed circuit substrate 9.

The desired circuit is formed on the printed circuit substrate 9. The plural stationary contacts 35 are to be contacted with the contact points 31 of the resilient contact pieces 30. The printed circuit substrate 9 also has plural pairs of rectangular holes 36 formed therethrough for inserting the legs 22, which mount the cases 4. Since the oblique surfaces of the claws 23 are contacted with the edges of the rectangular holes 36, when the legs 22 of the cases 4 are inserted into the rectangular holes 36 and the cases 4 strongly depressed, the legs 22 are bent inside so that the ends of the claws 23 pass through the rectangular holes 36. Simultaneously the bent portions of the legs 22 are returned to their original states by their resiliency with the result that the claws 23 are engaged with the edges of the rectangular holes 36 so that the cases 4 are secured to the printed circuit substrate 9. There are also provided plural holes 37 at the printed circuit substrate 9 for inserting the screws 10. The mounting of the printed circuit substrate 9 to the frame 2 may be made by alternative means instead of the screws 10.

Assemblying of the snap-action nodally operable push-button switch of the present invention will now be described.

The sliding lever 5 is inserted into the small-sized hollow rectangular portion 18 of the case 4, the coil spring 6 is then inserted into the hole 25 of the lever 5, the bent portion of the movable contacting plate 7 is placed at the side of the coil spring 6 so that the holes 32 of the four corners are engaged with the projections 21 of the four corners of the case 4, the movable contacting plate 7 is mounted to the case 4, the holes 33 of the four corners of the insulating plate 8 are engaged with the projections 21 of the four corners of the case 4 in the state that the rectangular holes 34 of the insulating plate 8 coincide with the stationary contacts 35 of the printed circuit substrate 9, and the insulating plate 8 is mounted to the case, then the projections 21 of the case 4 are punched, and then the movable contacting plate 7 and the insulating plate 8 are fixed to the case 4, and thus the operating unit 3 is assembled.

As shown in FIG. 4, the assembled operating unit 3 is so constructed that the central stripe of the movable contacting plate 7 is bent upwardly as shown in the drawing, so as to push upwardly the coil spring 6. The coil spring 6 urges upwardly the lever 5 with the result that the stoppers 27 of the lever 5 are contacted with the step 16 of the case 4 so as to prevent the lever 5 from being discharged out. The desired number of the operating units 3 are previously assembled, and then the legs 22 of the case 4 of the operating unit 3 are press-fitted within a pair of rectangular holes 35 of the printed circuit substrate 9, and then the claws 23 of the legs 22 are engaged with the edges of the pair of rectangular holes 36 so that the operating units 3 are secured to the printed circuit substrate. Thus, a desired number of operating units 3 are mounted to the printed circuit substrate 9.

Then, the cases 4 of the respective operating units 3 are engaged with the holes 15 of the frame 2, i.e., the frame 2 is located on plural operating units 3, and then screws 10 are inserted into plural holes 37 of the printed circuit substrate and are screwed with the thread holes 17 of the frame 2 and are then tightened so as to secure the printed circuit substrate 9 to the frame 2, and the operating units 3 are fixed between the printed circuit substrate 9 and the frame 2. Then, the mounting shafts 11 of the respective knobs 1 are engaged so as to press-fit the projections 12 to the holes 24 of the levers 5 presented at the holes 14 of the frame 2 thereon, and then the knobs 1 are turned at 90.degree. so as not to be discharged out from the lever 5 to complete the assembling.

Then, the operation of the nodally operable push-button switch of the present invention will now be described.

The central stripe 28 of the movable contacting plate 7 of the push-button switch, assembled but not yet operated, is bent upwardly as in FIG. 7A. At the side of the lever 5, the free ends of the resilient contact pieces 30 are also directed upwardly. The contact points 31 (at the free ends of the resilient contact pieces 30) are separated from the stationary contacts 35 of the printed circuit substrate 9, and the push-button switch is in its open state. The bent portion of the central stripe 28 of the movable contacting plate 7 pushes the lever 5 and the knobs 1 upwardly, and the stoppers 27 of the lever 5 are contacted with the step 16 of the case 4 to hold the lever 5 in the stopped state.

When the knob 1 is now depressed, the lever 5 compresses the coil spring 6, which spring 6 urges the center of the central stripe 28 of the movable contacting plate 7. When the coil spring 6 is compressed to a certain degree, the central stripe 28 is also started to be in flexure, and when the coil spring 6 is further compressed, the central stripe 28 cannot endure the depression so that the central stripe 28 is abruptly deformed from the state shown in FIG. 7A to that shown in FIG. 7B, with the result that the center of the central stripe 28 is reversely bent and the inclined direction of the resilient contact pieces 30 are also abruptly changed so that the contact points 31 are abruptly moved downwardly. The contact points 31 are then positively contacted with the stationary contacts 35 of the printed circuit substrate 9, and then the circuit is closed. The reversing speed of the central stripe 28 of the movable contacting plate 7 when reversely bent is faster than the moving speed of the knob 1 up to that time, (a type of toggle action), and the depression to the knob 1 when reversely bent is abruptly reduced, and accordingly the knob 1 is nodally moved. When the knob 1 is further depressed even after the circuit is closed, the coil spring 6 and the central stripe 28 of the movable contacting plate 7 are further compressed so that the central stripe 28 of the movable contacting plate 7 becomes as shown in FIG. 7C so as to provide sufficient moving allowance of the knob 1. When the depression is released, the central stripe 28 of the movable contacting plate 7 urges the coil spring 6, by its own resiliency, and returns to its original bent state and the coil spring 6 is also returned to its original state by its resiliency thereof so as to simultaneously return the knob 1.

A resilient member such as spring 38, see FIG. 8, formed of rubber of rubber resilient material as shown in FIG. 8 may be used instead of the coil spring 6.

The following advantages and effects can be provided by the nodally operable push-button switch of the invention:

It should be understood from the foregoing description that since the nodally operable push-button switch of the present invention comprises the movable contacting plate 7 which is shortened at the edges 29 by drawing so that the opening and closing of the switch is nodally conducted and the switch also comprises spherical contact points 31 at the free end of the resilient contact pieces 30 so as to effect point-contact with the stationary contacts 35 on the printed circuit substrate 9, positive separation of the point contacts 35 can be attained so as to improve the electric characteristics.

It should also be understood that since the coil spring 6, such as resilient material made of rubber or rubber substance, is disposed between the movable contacting plate 7 and the lever 5 in the switch of the invention, the contacting sensitivity of the contacts is soft and the play of the moving degree of the knob 1 may be sufficiently provided so as to improve the contacting sensitivity.

It should also be understood that since the nodally operable push-button switch of the invention comprises wiring portion of operational circuit, stationary contacts and circuit portion of push-button switch formed on one printed circuit substrate and said operational circuit mounted at the wiring portion of the operational circuit, operating units mounted at the push-button switch portion as one-touch operation type simply assembled compared with the conventional desk type electronic computer which as separate push-button portion and operational circuit portion and lead wires for connection the former to the latter, the assembling process, wiring parts and the number of wiring processes can be reduced so as to assemble the desk type electronic computer less expensively.

It should also be understood that since the knobs 1 and frame 2 and operation units 3 are combined with the printed circuit substrate 9 in the switch of the present invention, so that when push-button switches for different key numbers are produced, only the designs of printed circuit substrate and the frame 2 may be changed and when different design of the knob 1 is necessary, only the knob 1 of different design may be formed and may be mounted thereto, it is advantageous for producing small numbers and various types of push-button switches.

Claims

What is claimed is:

1. A nodally operable push-button switch comprising a case, and a flexible conducting metal plate, said plate having a normally curved central stripe and a pair of rectangular holes at both sides of said central stripe integrally formed therewith and also having a pair of resilient contact pieces integrally extended therefrom smaller than the size of the holes, and opposite side edges of said metal plate being drawn so that they are shorter than the said central stripe.

2. A nodally operable push-button switch as set forth in claim 1, further comprising a lever mounted slidably into said case, and a resilient means disposed between the said curved central stripe and said lever.

3. A nodally operable push-button switch as set forth in claim 2, further comprising a printed circuit substrate having stationary contacts, and a frame, said case having legs with claws integrally projected therefrom said claws being engaged with holes provided in said printed circuit substrate, said lever being slidably inserted into said case, and an insulating plate provided on said printed circuit substrate and having a pair of rectangular holes formed therethrough for contacting said stationary contacts.

4. A nodally operable push-button switch as set forth in claim 1, further comprising a printed circuit substrate having a plurality of stationary contacts, a frame having a plurality of holes aligned in a manner crossing at right angles with each other, a plurality of cases each having legs, each of said legs having claw portion for engaging with said printed circuit substrate, a lever slidably inserted into said case, a movable contacting plate disposed at the bottom of said case, said contacting plate having a central strip with a bent portion and having a pair of rectangular holes at both sides of central stripe integrally formed therewith and also having a pair of rectangular resilient contact pieces integrally extended therefrom which are smaller than the size of the holes, and opposite side edges of said metal plate being drawn to be shorter than the central stripe of said metal plate, an insulating plate having a pair of rectangular holes for contacting the stationary contacts provided on said printed circuit substrate, said lever having a spring hole, a resilient material inserted between the spring holes of said lever and the bent portion of said movable contacting plate to form an operating unit, a plurality of said operating units mounted to said printed circuit substrate and said frame, and a plurality of knobs with mounting shafts engaged with the holes of said levers, said levers being slidably inserted into the holes of said frame.