Momentary Contact, Non-bounce Switch

Abstract

A novel switch, particularly useful for achieving reliable, reproducible, momentary contact, as is desirable in the operation of electronic keyboard actuators. The switch is characterized by a spring means carrying a weighted contact which, on being biased by a cam in a first direction away from a contact, is allowed to snap back, with a predetermined and inherent momentum, beyond its normal position to make a momentary electrical connection with a stationary contact and thereby make a temporary circuit through the switch.

Description

BACKGROUND OF THE INVENTION

A great deal of development work has been directed toward the manufacture of improved impulse switches. By "impulse switch" is meant a switch which on being actuated, as by finger pressure, will deliver a single contact having a duration not dependent upon a manual de-activation of the switch, for example not dependent on the release of finger pressure from a switch activating button. Such switches are much in demand for use in operating fast electronic apparatus and particularly in demand for so-called electronic keyboards wherein a large number of such switches are assembled. One of the desirable characteristics of these is that they deliver reproducible signals which are as little dependent as is possible upon the touch of the operator. And, of course, since so many of these switches are assembled onto a switchboard, it is important to achieve such desirable operating characteristics at as low a cost as possible.

Among switches known in the art, most have an "on time" which is dependent in part upon the speed at which the operator depresses or otherwise manipulates the switch-actuating button. For example, see such switches as are described in U. S. Pat. Nos. 2,616,009, 3,142,743, and 3,375,340, to Roeser, Borges and Wright, respectively. Switches which do not have this feature are usually of relatively expensive or complex design or have some other limiting feature. For example, see U. S. Pat. No. 3,073,935 to Smusz which relies upon a permanent magnet to restrain motion and position of the contact members.

SUMMARY OF THE INVENTION

Therefore, it is an object of the invention to provide an improved impulse switch.

It is a further object of the invention to provide an inexpensive impulse switch adapted to yield a constantly reproducible output signal despite operating habits of the switch operator.

Another object of the invention is the provision of an improved switch, the operation of which is free of spurious signals caused by "bounce" of a contact element.

It is still another object of the invention to provide a switch having the advantages described in the foregoing paragraphs and which, on being actuated, responds to the touch in such a manner as to confirm actuation by a tactile feeling to the switch operator.

Other objects of the invention will be obvious to those skilled in the art on reading this application.

The above objects have been substantially achieved by construction of a switch wherein a pendular mass and a contact making member are mounted for biased movement on a deflectable member. As the switch is actuated, the pendular mass is initially biased, on its deflectable carrying member, away from a stationary contact. As the actuation stroke reaches a predetermined position, the pendular mass is released; thereupon it carries the deflectable member back beyond its normal pre-actuation position and causes it to strike the stationary contact with an exactly reproducible stroke related to the mass of the pendular member and resiliency of its carrier, and then to spring away from the stationary contact.

ILLUSTRATIVE EMBODIMENT OF THE INVENTION

In this application and accompanying drawings, there is shown and described a preferred embodiment of the invention and suggested various alternatives and modifications thereof, but it is to be understood that these are not intended to be exhaustive and that other changes and modifications can be made within the scope of the invention. These suggestions are selected and included for purposes of illustration in order that others skilled in the art will more fully understand the invention and the principles thereof and will be able to modify it in a variety of forms, each as may be best suited in the condition of a particular case.

IN THE DRAWINGS

FIG. 1 is a plan view of a non-bounce switch constructed according to the invention;

FIG. 2 is a side elevation, in section, taken along lines 2--2 of FIG. 1;

FIGS. 3, 4, and 5 are similar to FIG. 2, but show the sequence of operation of the switch;

FIG. 6 is a side elevation, in section, on lines 6--6 of FIG. 1.

Referring to FIG. 1, it is seen that an impulse switch 10 comprises a housing 12 which forms an electrically insulating support and within which are positioned two fixed electrical contact elements 14 and 15 and two movable electrical contact elements 16 and 17. Movable contacts 16 and 17 are each carried on deflectable conductive rods 18 or 19. Each of rods 18 or 19 has one end 20 free to move in housing 12; the other end 22 is attached to a fixed electrical terminal 24 or 25 which is partially embedded within housing 12.

As seen in FIG. 2, cam assembly 26 is preferably centrally mounted in housing 12 and is connected to an operating rod 28 which, in the usual practice, will be attached to a push-button, or key, 30. As seen in FIG. 3, integrally molded into housing 12 are stationary cam surfaces 32 and 33. Surfaces 32 and 33, as will be seen, form means to guide rods 18 or 19 to their normal position when the cam assembly 26 is pushed upwardly by return spring 34 which is mounted between the operating rod 28 and the bottom of housing 12.

Cam assembly 26 comprises an operating head 36 which not only carries primary cam surfaces 38 and 39 (as shown in FIG. 2 to be in contact with rods 18 or 19), but also carries an upper surface 40 and 41 which acts with stationary cam surface 32 or 33 to position rods 18 or 19 on the upper stroke thereof and a restraining surface 42 or 43 which is adapted to restrain rods 18 or 19 in snug position after each switching sequence, as will be disclosed more fully below.

In a typical operational sequence, switch 10 is first in the position shown in FIGS. 1 and 2. Rods 18 and 19 rest against restraining surfaces 42 and 43 of cam assembly 26, just about where surfaces 42 and 43 and cam surface 38 and 39 join. In this position, as best seen in FIG. 1, there is a substantial gap between electrical contacts 14 and 16 and electrical contacts 15 and 17. The impulse switch, as a consequence, is in its normally open mode. Then, as operating pressure is applied to push-button 30, operating rod 28 is depressed and rods 18 and 19 each slide outwardly along a cam surface 38 or 39. During this depression of the cam operating head 36, spring 34 is compressed, but the resistance of spring 34 is small compared to the total force required to depress operating head 36 against the resistance of rods 18 and 19. As the depression of operating head 36 continues, the free ends 20 of rods 18 and 19 are biased outwardly toward the housing carrying with them movable contact-bearing members 16 and 17. When operating head 36 is depressed to the upper edge of primary cam surfaces 38 and 39 (as seen in FIG. 3), outward biasing pressure on rods 18 and 19 is maximized and then (as seen in FIG. 4) this pressure is suddenly removed as the operating head is depressed still further to allow the inward movement of operating rods 18 and 19, a movement roughly parallel to surface 40 and 41. This movement is not arrested until contacts 16 and 17 have snapped back to contact, and hence close a circuit with, stationary contacts 14 and 15. This contact is temporary and rods 18 and 19 immediately bring the contacts 16 and 17 back to their normal position, i.e. the position shown in FIG. 1.

At the time that rods 18 and 19 are no longer being biased apart by pressure of the operator on push-button 30, a trained operator will sense a sudden release of pressure and remove his finger from the push-button. His release of the button, however, has no effect whatsoever on the time of contact between contacts 16 and 17 and contacts 14 and 15. That time was predetermined by the mass and velocity imparted to contacts 16 and 17 by the energy stored in rods 18 and 19, the elasticity of the contacts themselves, and other such predetermined physical characteristics of the switch. It should also be noted that the rate of speed at which the button was depressed is of no consequence since the rods 18 and 19 are selected so that they remain in contact with cam surfaces 38 and 39 throughout any foreseeable rate of actuating movement.

In any event, after contacts 16 and 17 hit contacts 14 and 15, they return to their original position and, at about the same time, spring 34 compressed by the actuating stroke of the pushbutton, is released and commences the returning of cam assembly 26 to its original position. As the cam 26 moves upwardly, rods 18 and 19 are forced against stationary cam surfaces 32 and 33 by upper surface 40 of cam 36. Consequently, the rods 18 and 19 are again strained outwardly (as shown in FIG. 5); this time, however, they are being pushed outwardly along upper surfaces 40 by cams 32 and 33. When rods 18 and 19 reach the edge formed by the juncture of surfaces 40 and 41 and 38 and 39, they slide downwardly to their starting position at restraining surface 42 and 43. In this position rods 18 and 19, and hence contacts 16 and 17, are held snugly to prevent movement or damage.

It is to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described and all statements of the scope of the invention which might be said to fall therebetween.

Claims

1. In a momentary contact switch comprising an insulating support and at least one pair of electrical contacts mounted in said support, adapted to be contacted momentarily, the improvement wherein:

a first of said pair of contacts is attached to a deflectable member;

a switch actuating member comprises means for deflecting said deflectable member a predetermined distance from its normal position, and means for releasing said deflectable member after said deflection; and

a pendular mass associated with said member and forming means to carry said deflectable member back through its normal position and carry said first contact into said momentary contact with a second of said pair of

2. A switch as defined in claim 1, wherein:

said pendular mass forms the contact surface of the first of said pair of

3. A switch as defined in claim 1, wherein:

said deflectable member is a rod carrying said pendular mass proximate one

4. A switch as defined in claim 1, wherein:

said deflecting means is a cam assembly mounted for relative movement against said deflectable member;

said cam being so shaped that, as it is moved relative to the deflectable member, said member encounters a first cam surface forming means to deflect said member in a first direction away from said stationary contact, and then encounters a sharp recess in said cam forming means to release said member inwardly along a second cam surface toward said stationary contact; and

wherein said second cam surface and a fixed cam member are mounted for relative movement with one another to form means to urge said deflectable

5. A switch as defined in claim 3, wherein:

said deflecting means is a cam assembly mounted for relative movement against said deflectable member;

said cam being so shaped that, as it is moved relative to the deflectable member, said member encounters a first cam surface forming means to deflect said member in a first direction away from said stationary contact, and then encounters a sharp recess in said cam forming means to release said member inwardly along a second cam surface toward said stationary contact; and

wherein said second cam surface and a fixed cam member are mounted for relative movement with one another to form means to urge said deflectable

6. Apparatus as defined in claim 1, wherein:

said switch is free of any contact-making means except that formed by the

7. Apparatus as defined in claim 4, wherein:

said fixed cam is integral with said insulating support member; and

said cam assembly is biased against a return spring, positioned between

8. Apparatus as defined in claim 1, wherein:

9. Apparatus as defined in claim 1, wherein:

the deflectable contact member is fixed to said support proximate one end

10. Apparatus as defined in claim 4, wherein:

said cam assembly is adapted to immobilize said deflectable member when said switch is not in use;

said immobilization being achieved by said deflectable member being in

11. Apparatus as defined in claim 5, wherein:

said switch is free of any contact-making means except that formed by said

12. Apparatus as defined in claim 3, wherein:

said switch is free of any contact-making means except that formed by the

13. A momentary contact, non-bounce switch comprising:

a pair of electric contacts each including a relatively heavy weight carried at the free end of a stiff rod spring, the other ends of each said rod being anchored against movement;

plunger cam means mounted in said switch for reciprocal movement, said means having a pair of inclined cam faces each arranged to flex one of said contacts sidewise and then release the same;

a pair of stationary contacts in said switch, each in the path of one of said movable contacts and arranged to momentarily close a circuit when one of said movable contacts is released by said cam means to flex thereagainst; and

a pair of stationary cam faces in said switch, operatively associated with said plunger cam means, to prevent said electric contacts from striking said stationary contacts more than once.