US3739127A

US3739127A - Keyboard pulse switch

Info

Publication number: US3739127A
Application number: US00227058A
Authority: US
Inventors: E Long; W Cherry
Original assignee: Cherry Electrical Products Corp
Current assignee: Cherry Corp
Priority date: 1972-02-17
Filing date: 1972-02-17
Publication date: 1973-06-12
Anticipated expiration: 1990-06-12
Also published as: FR2172069B3; IT960987B; JPS4889363A; FR2172069A1; GB1345309A; DE2230193A1

Abstract

An electric switch having a momentary pulse-like action embodied in a housing through which an actuator is adapted to be reciprocally moved, with the switch associated with a so-called keyboard assembly utilized in electronic equipment such as computers, data processing machines, and electric typewriters. A trip member is mounted on the actuator with limited pivotal movement relative thereto. A spring contact is stressed by the trip member, and when released springs into momentary contact with a stationary contact with a stationary terminal. The spring contact may be coated with lead, tin, or other dense material to absorb and restrain bounce of the contact.

Description

United States Patent 1 Long et al. June 12, 1973 KEYBOARD PULSE SWITCH 3,530,269 9/1970 Lucas et al. 200/166 11 x Inventors: Eric L. g Walter L. y 789,814 5/1905 McGrath 200/166 H UX both ofwaukegan Primary ExaminerHerman J. Hohauser Assistant ExaminerRobert A. Vanderhye [73] Assignee: Cherry Electrical Products Att0rneyEdward C. Threedy Corporation, Waukegan, 111. 22 Filed: Feb. 17, 1972 [57] @STRACT An electnc switch having a momentary pulse-like ac- 1 PP N05 227,058 tion embodied in a housing through which an actuator is adapted to be reciprocally moved, with the switch as- 152 U.S. c1. 200/160, 200/166 H Sociated with a Called keYbOaFd assembly utilized in 511 1m. (:1 110111 13/50, HOlh 1/50 electmnic equipment Such as mputers, data process' [58] Field of Search 200 160, 166 H, 73, machine-51a electric YP A trip member ZOO/67 DA is mounted on the actuator with limited pivotal movement relative thereto. A spring contact is stressed by [56] References Cited the trip member, and when released springs into m0- UNITED STATES PATENTS mentary contact with a stationary contact with a sta- Y tionary terminal. The spring contact may be coated gz g zf with lead, tin, or other dense material to absorb and re- 3:662:l38 5 1972 111111155151. 200 160 bmmce of the Contact 2,004,610 6/1935 Jones 200/166 H UX 7 Claims, 7 Drawing Figures PMENTE l] 21975 KEYBOARD PULSE swrrcu SUMMARY OF THE INVENTION An electric switch adapted to be associated with a keyboard type switch assembly and having a momentary circuit-making pulse. The switch includes a reciprocal movable elongated actuator, a stationary terminal, and a second terminal biased in a predetermined spaced position relative to the fixed terminal, with the second terminal being physically moved against its bias and farther away from the fixed terminal by a pivotal trip member carried by and moved with the actuator.

The trip lever has one end in contact with one of the circuit-making contacts at a point below its centerline as well as beneath the point of pivotal connection to the actuator. This arrangement results in a line of forced movement between the lever and the circuit-making contact which increases as the actuator is moved in one direction and the point of pivotal connection between the lever and the actuator approaches the line of contact between the lever and the circuit-making contact.

By a prescribed degree of travel, the actuator member moves the trip member over a cam surface provided by the second terminal to a point of forced reactance where the trip member is uncontrollably pivoted free of contact with the second terminal, permitting it to overreact through the kinetic energy developed therein by an increased biased loading of the trip member as it moves over the cam surface of the second terminal, such that when the second terminal is freed from the trip member, it will strike momentarily the fixed contact, establishing a single electrical pulse therebetween.

GENERAL DESCRIPTION The objects of the invention are best achieved through the preferred form of embodiment as disclosed in the accompanying drawings, wherein:

FIG. 1 is a perspective view of the keyboard pulse switch;

FIG. 2 is a detailed side elevational view of the pulse switch of this invention in its normal or raised position;

FIG. 3 is a fragmentary detailed sectional view similar to FIG. 2, but showing the parts in an intermediate actuated position;

FIG. 4 is a fragmentary sectional detailed view similar to FIG. 3, showing the parts in yet another actuated position;

FIG. 5 is a fragmentary sectional detailed view similar to FIG. 4, showing the parts thereof in a position during the return of the switch actuator and trip lever;

FIG. 6 is an enlarged perspective view of the components of the invention in an exploded relation; and

FIG. 7 is a detailed sectional view showing the interior of the housing for such switch.

This invention relates to a push-button type switch which may be readily used in what is known as keyboard equipment utilized in computers, data processing machines, calculators, and electric typewriters.

The object of this invention is to provide in such a switch assembly a means whereby a single electrically energized pulse is established between current conductive terminals, with the switch providing by its structural and component arrangements a teaseproof yet positive switching action as desired.

Referring to FIG. 1, the keyboard pulse switch 10 of this invention is shown as including a hollow housing 11, the normally open base thereof being closed by a base plate 12.

The top wall 13 of the housing 11 provides a central rectangularly shaped opening 14 through which the stem 15 of an actuator 37 is adapted to be reciprocally moved. The free or exposed end of the actuator stem carries a cap 16 having a configuration as required by the environment in which the switch 10 is placed.

Referring to FIG. 6, it is shown that the base plate 12 on one face thereof provides a raised platform 17 which includes adjacent to one side edge,

parallel grooves

18 and 19 which have a portion thereof extending through the base 12 so that certain hereinafter defined terminal ends may be journalled so as to be positioned exteriorly of the switch housing 10. A center recess 20 is formed in the platform 17 and is positioned between the

grooves

18 and 19 and a raised generally rectangularly shaped lug 21.

Adapted to be mounted on the base plate 12 is a fixed terminal plate 22 which provides on its bottom edge 23 a depending terminal 24 adapted to project through the groove 18 so as to be disposed beneath the base 12 as shown in FIGS. 1 and 2 through 5.

The upper edge of the fixed terminal 22 provides a head 25 which is adapted to be projected into a retaining recess 26 formed on the inner wall surface 27 of the top wall 13 of the housing 11.

Mounted in the groove 19 is a second terminal 28. This terminal 28 provides an enlarged base portion 29 which is received in the groove 19 and from which depends a terminal 30 adapted to be projected through the base 12 so as to be exposed therefrom as shown in FIGS. 1 and 2 through 5.

Extending laterally from one longitudinal edge 31 of the terminal 28 is an arm 32 which is preformed to provide a cam surface which consists of a flat face 33 that extends obliquely with respect to the longitudinal plane of the terminal 28 and which terminates at its lower edge into an angularly reversely bent face 34.

It should be noted that when the second terminal 28 is mounted upon the base 12, the portion thereof which extends vertically from its enlarged base 29 is biased out of the normal longitudinal plane of the terminal 28 in the direction of the fixed terminal 22, but not to the degree that its contact head 35 touches the contact head 36 of the stationary terminal 22, for the purpose hereinafter made apparent.

The switch includes as an operative component the actuator 37, which actuator comprises a generally rectangularly shaped body 38 at the lower end of the stem 15 and also providing a frictional insert 39 adapted to be pressfitted into the hollow internal shank 40 of the cap 16 of the switch. The bottom edge of the body 38 of the actuator 37 is notched as at 41 to provide a longitudinally extending center stud 42.

Extending laterally from each longitudinal side edge of the body 38, adjacent to either side of the center stud 42 are guide lugs 43 which are adapted to project into opposing channels 44 formed on the inner wall surfaces of the side walls of the housing 11, as shown in FIG. 7.

Also formed on the opposite longitudinal side edges of the body 38 of the actuator 37 at a point approximately in the middle line thereof, are a pair of laterally extending

shoulders

45 and 46. These shoulders, like the lugs 43, are adapted to project into and move through the channels 44.

Reference is made to the shoulder 46 which is formed so as to have one corner thereof notched out as at 47 so as to provide a small stop piece 48.

Between the shoulder 46 and the lug 43 and mounted upon a pin 49, is a trip lever 50. This trip lever 50 provides a reduced cam face 51 at one end thereof, with the cam face 51 lying below the plane of a centerline drawn through the trip lever 50 as well as beneath the aperture 52 formed in the trip lever 50 which receives the pivot pin 49.

Adjacent the opposite end of the trip lever 50 and formed on the upper longitudinal edge thereof, is a stop flange 53. This stop flange 53 is of a height equal to the thickness of the stop piece 48, so that when the trip lever 50 is mounted on the actuator 37 and the switch is in its normal position, the stop piece 48 will engage the upper longitudinal edge 54 of the trip lever 50, while the stop flange 53 will engage the under wall surface of the top 13 of the switch housing 11, as seen in FIG. 2.

The actuator is maintained in its normal position as shown in FIG. 2 by a coil spring 55 which has one end disposed within the center recess of the base 12, while its opposite end embraces the stud 42 provided adjacent the bottom edge of the actuator 37.

In its normal or rest position and with the parts related to one another as depicted in FIG. 2, the cam face 51 will be in engagement with the flat face 33 of the arm 32 provided by the terminal 28. In this position the

contact heads

35 and 36 of the

terminals

22 and 28 are spaced apart and out of contact with each other. As the plunger or actuator 37 is depressed by an external force applied against the cap 16, the actuator 37 together with the trip lever 50 will move inwardly of the housing 11 in the direction of the base 12 against the tension of the spring 55. During such movement, the cam face 51 of the trip lever 50 will ride upon the flat face 33 of the arm 32 of the terminal 28 and because of its formation a camming effect will take place, causing the terminal 28 to be spring-loaded in a direction away from the fixed terminal 22. Because of the relation between the pivotal connection of the trip finger 50 with the pivot pin 49 and the cam face 51 thereof, the trip lever 50 will remain in its generally transverse plane with respect to the longitudinal axis of the actuator 37 during this initial movement as shown in FIG. 3.

As the actuator 37 and the trip lever 50 continue downward movement, the bottom edge of the trip lever 50 will engage the upwardly projecting lug 21 provided by the base 12, causing the trip lever 50 to pivot in an anti-clockwise direction as shown in FIG. 4, causing the cam face 51 thereof to ride off the flat face cam surface 33 of the arm 32 and to extend beneath the reversely bent face 34 thereof. Because the terminal 28 is positioned relative to the fixed terminal 22 in a pre-biased condition, and it is further spring-loaded against that biased position by the trip lever 50, when the latter is pivoted out of contact with the arm 32 of the terminal 28 as hereinbefore described, the reaction of the terminal 28 will be such that it effects an almost uncontrollable pivoting of the trip lever 50 out of contact with the arm 32 of the terminal 28, as shown in FIG. 4. The freed spring-loaded terminal will then move with a sufficient reaction beyond its original biased position, such that its contact head 35 will strike the contact 36 of the terminal 22, causing a momentary electrical tioned terminal 28 is principally one of action and reac-.

tion, that is, first being forcibly moved farther away from its predetermined biased position with respect to terminal 22, and secondly permitted to have a free reaction movement beyond its original biased position into striking contact with the terminal 22, with a return therefrom to its original position, care must be provided to prevent what is commonly known as contact bounce, i.e., the repeated vibrational striking of the

contacts

35 and 36 of the

terminals

22 and 28, which establish more than a single current conductivity or poles therebetween. To reduce this condition, it has been found that by plating the terminal 28 with a lead, tin, or alloy thereof, a thickness on each side of the terminal in the range of not less than 4 percent of the base thickness of the terminal, such plating because of the density and weight of the material thereof will absorb and restrain bounce in the free end of the terminal due to the action and reaction created therein.

From the foregoing, it is apparent that by the relationship of the components of the switch as described and at the moment that the cam face 51 moves off the cam surface of the arm 32, there is an uncontrollable movement of the terminal 28 into a switch-closing position.

As the actuator 37 is allowed to return to its original position under the force of the spring 55, the trip lever 50 will move upwardly with the actuator 37, and the cam face 51 thereof will be restrained by its engagement with the face 34 of the cam surface of the arm 32 until the uppermost corner of the stop flange 53 engages the under side of the top wall 13 of the housing 11, as seen in FIG. 5, so as to act as a pivot point for the trip lever 50 as it is caused to move upwardly with the actuator 37 until it resumes its original position as seen in FIG. 2.

However, it should be noted that during this return movement and by reason of the frictional restraint between the face 34 of the cam surface of the arm 32, that the switch cannot be reactivated by a commencing downward stroke of the actuator 37 before it returns to its original position as shown in FIG. 2this by reason of the fact that before the trip lever 50 is pivoted into such original position, it will not act to additionally spring-load the terminal 28 to such a degree that the kinetic energy developed therein would be sufficient to cause it to move with a reaction sufficient to have it strike the contact 36 of the fixed terminal 22.

While we have illustrated and described the preferred form of construction for carrying our invention into effect, this is capable of variation and modification without departing from the spirit of the invention. We, therefore, do not wish to be limited to the precise details of construction set forth, but desire to avail ourselves of such variations and modifications as come within the scope of the appended claims.

Having thus described my invention, what I claim as new and desire to protect by Letters Patent is:

1. An electrical push-button pulse switch having a hollow housing for a stationary contact-bearing terminal, a second contact-bearing terminal having a free end biased in the direction of but spaced from the stationary terminal, and an elongated actuator reciprocally movable in the housing, wherein the improvement comprises a. a trip member carried by the actuator and being of a length so as to extend beyond the longitudinal edges of the actuator and reciprocally movable therewith through the housing,

b. means connecting said trip member to the actuator for free limited pivotal movement relative thereto,

0. said trip member providing a pre-shaped end portion extending beyond one face of the actuator in the direction of and in contact with the second terminal to resiliently bend the free end of said terminal against its bias,

d. means on the second terminal extending in the direction of and in the path of movement of said preshaped end portion of said trip member for increasing the bending of said second terminal against its bias by movement of said preshaped end portion thereover,

e. means on the actuator and in contact with said trip member for preventing pivotal movement of said trip member in a direction opposite to that of the movement of the actuator when the same is moved in one direction through the housing, and means within said housing and in the path of travel of said trip member to initially pivot said trip member in the direction of movement of the actuator to move said preshaped end portion out of contact with the means on the second terminal to permit the trip member to freely pivot with a snap action in the direction of movement of the actuator to permit the second terminal to snap in the direction of its bias into momentary contact with the fixed terminal.

2. An electrical push-button pulse switch as defined by claim 1 wherein said means on the free end of the second terminal comprises an arm extending laterally from one longitudinal edge of the second terminal adjacent to its free end and providing a surface angled downwardly and in the direction of the actuator and in the path of movement of said one end of said trip member.

3. An electrical push-button pulse switch as defined by claim 1 wherein said means within said housing and within the path of travel of said trip member that pivots the same in one direction, comprises a lug extending in a spaced parallel relation to the actuator and in the path of movement of the other end of said trip member so as to contact the same and cause said trip member to pivot about its pivotal connection with said actuator in one direction so as to move said one end of said trip member out of contact with said angled surface of said second terminal.

4. An electrical push-button pulse switch as defined by claim 3 wherein said means on the free end of said second terminal providing an angled surface, comprises an arm extending laterally from one longitudinal edge of the second terminal adjacent to its free end and providing a surface angled downwardly and in the direction of the actuator and in the path of movement of said one end of said trip member.

5. An electrical push-button switch as defined in claim 4, wherein said trip member comprises a generally rectangularly shaped substantially fiat plate extending transveersely to either side of the actuator, said pre-shaped end portion of said trip member being tapered to a point below the centerline thereof and said means for pivotally connecting said trip member to the actuator so as to maintain a forced contact between said tapered end of said trip member and said means on the second terminal until said trip member is initially pivoted in the direction of movement of the actuator, permitting said forced contact to freely pivot with a snap action said tapered end of said trip member out of contact with the second terminal.

6. An electrical push-button pulse switch as defined by claim 1, wherein said second terminal, is plated with an electrically conductive metallic material on each side thereof to a thickness in the range of not less than four per cent of the base thickness of said second terminal, whereby the movement of said second terminal will be dampened so as to restrict such movement to a single current-conducting contact between said second terminal and said stationary terminal when said trip member is disengaged from the free end of said second terminal.

7. An electrical push button pulse switch as defined by claim 1, wherein said trip member comprises a generally rectangularly shaped substantially flat plate extending transversely to either side of the actuator, said pre-shaped end portion of said trip member being tapered to a point below the centerline thereof, and said means for pivotally connecting said trip member to the actuator so as to maintain a forced contact between said tapered end of said trip member and said means on the second terminal until said trip member is initially pivoted in the direction of movement of the actuator, permitting said forced contact to freely pivot with a snap action said tapered end of said trip member out of contact with the second terminal.

Claims

1. An electrical push-button pulse switch having a hollow housing for a stationary contact-bearing terminal, a second contact-bearing terminal having a free end biased in the direction of but spaced from the stationary terminal, and an elongated actuator reciprocally movable in the housing, wherein the improvement comprises a. a trip member carried by the actuator and being of a length so as to extend beyond the longitudinal edges of the actuator and reciprocally movable therewith through the housing, b. means connecting said trip member to the actuator for free limited pivotal movement relative thereto, c. said trip member providing a pre-shaped end portion extending beyond one face of the actuator in the direction of and in contact with the second terminal to resiliently bend the free end of said terminal against its bias, d. means on the second terminal extending in the direction of and in the path of movement of said pre-shaped end portion of said trip member for increasing the bending of said second terminal against its bias by movement of said preshaped end portion thereover, e. means on the actuator and in contact with said trip member for preventing pivotal movement of said trip member in a direction opposite to that of the movement of the actuator when tHe same is moved in one direction through the housing, and f. means within said housing and in the path of travel of said trip member to initially pivot said trip member in the direction of movement of the actuator to move said preshaped end portion out of contact with the means on the second terminal to permit the trip member to freely pivot with a snap action in the direction of movement of the actuator to permit the second terminal to snap in the direction of its bias into momentary contact with the fixed terminal.

5. An electrical push-button switch as defined in claim 4, wherein said trip member comprises a generally rectangularly shaped substantially flat plate extending transveersely to either side of the actuator, said pre-shaped end portion of said trip member being tapered to a point below the centerline thereof and said means for pivotally connecting said trip member to the actuator so as to maintain a forced contact between said tapered end of said trip member and said means on the second terminal until said trip member is initially pivoted in the direction of movement of the actuator, permitting said forced contact to freely pivot with a snap action said tapered end of said trip member out of contact with the second terminal.

6. An electrical push-button pulse switch as defined by claim 1, wherein said second terminal is plated with an electrically conductive metallic material on each side thereof to a thickness in the range of not less than four per cent of the base thickness of said second terminal, whereby the movement of said second terminal will be dampened so as to restrict such movement to a single current-conducting contact between said second terminal and said stationary terminal when said trip member is disengaged from the free end of said second terminal.