Pedestal And Spring Member For Key Actuator Of Diaphragm Switch

Abstract

A keyboard actuator which includes a first member adapted to be supported over a circuit board having a conductive pattern thereon and supporting a resilient conductive layer by way of an insulator layer having a window therethrough in line with at least a portion of the conductive pattern, a second member snapable into the first member and slidable while held therein, first and second resilient biasing means, the first biasing means separating the members and the second biasing means extending between the second member and the conductive layer.

Description

STATEMENT OF THE DISCLOSURE

This invention is directed to a new and improved keyboard actuator particularly adapted for use with a keyboard of the type utilizing a resilient conductive layer to make electrical contact with an electrical conductive contact.

In particular, the present invention is directed to a new and improved keyboard construction in which two parts, one movable and the other fixed in place are snaped together and two resilient biasing means are provided one of which is used to bias the movable part away from the fixed in place part and the other resilient biasing means is positioned between the movable part and the conductive layer in order to apply a force thereto to cause the conductive layer to contact the contact when a force is applied to the movable part.

The present invention is usable in place of the switch actuating means disclosed in copending U.S. Pat. applications Ser. No. 145,212 filed May 20, 1971 by Richard E. Seeger, Jr. and George T. Hodgson, Jr. and Ser. No. 154,752 filed June 12, 1971 by Richard E. Seeger, Jr. and William J. Lynn. The entire disclosure of these patent applications are incorporated herein by reference hereto.

The present invention permits a keyboard to be constructed with a minimum of parts, with a reduction in fabrication and assembly costs. The major parts (those not resilient in nature) used herein may be constructed of plastic moldable in a conventional manner thus providing significant cost savings.

BRIEF DESCRIPTION OF THE DISCLOSURE

The keyboard actuator of the disclosure includes a fixed in place member for mounting on a circuit board over a resilient conductive layer, the fixed in place member having means for retaining a movable member snapable therein and adapted for slidable movement therein and first and second resilient biasing or spring means, the first spring means separating the members and the other positioned to be forced against the conductive layer upon movement of the movable member towards the conductive layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view with the parts removed of a keyboard utilizing the actuator of the invention;

FIG. 2 is a sectional view taken along line 2--2 in FIG. 1 illustrating the key in position when at rest;

FIG. 3 is a sectional view similar to FIG. 2 illustrating the actuator when a force is applied thereto;

FIG. 4 is a sectional view taken along line 4--4 in FIG. 2; and

FIG. 5 is a sectional view taken along line 5--5 in FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Reference should now be had to FIGS. 1-5 for a description of the preferred embodiment of the disclosure. At 6 there is shown a keyboard which comprises an outer decorative frame 7 in which there is mounted the working parts of the invention. The frame may be mounted to the working parts as shown in the aforementioned U.S. Pat. application Ser. No. 145,122 or any other conventional manner. The operating parts of the invention include an insulator board 8 (e.g., Bakelite, Formica) of the conventional type used in printed circuit applications and having holes 8a formed therethrough.

At 9 there is provided an electrical contact means or electrical pathway which may be formed on the board using conventional printed circuit etching techniques i.e., where copper sheet is etched away or may be formed using conventional screening techniques where an electrically conductive coating is laid down.

Various circuit patterns are shown in the aforementioned patent applications which are incorporated herein by reference hereto.

At 10 there is shown an insulator layer for example, of plastic such as sold under the trademark Mylar and having a window 10a extending therethrough in line with at least a portion of the electrical contact means and mounting holes 10b. Positioned on the layer 10 is a resilient conductive layer or sheet 11 having mounting holes 11a. The layer 11 is selected of a material which may be forced through the window 10a into contact with the contact means 9 (see FIG. 3) and then springs back to its at rest position shown in FIG. 2 when a force applied thereto is removed.

Various materials may be used as the conductive layer as set forth in the aforementioned referred to applications with the preferred material being a conductive plastic formed of silicone rubber (rubber is defined as a plastic in the context used herein) filled with silver flakes e.g., between 10 to 80 percent by volume.

At 12 in the drawing there is shown the actuator of the invention which includes a fixed in place or base member 13 having a hollow cavity 13a with a lip 13aa formed along the top thereof. The cavity 13a is provided with two guide channels or slots 13b within the sidewall thereof and has a pedestal 13c extending upwardly therefrom. The pedestal is provided with a bore 13d as shown.

A movable or key member is shown at 14 on which indicia e.g., numbers or letters may be mounted thereon as shown in FIG. 1.

The movable member 14 is positioned for slidable up and down movement with respect to the member 13 and has a portion thereof positioned within the confines of the cavity 13a. The member 14 is provided with projections 14a which are positionable in the slots 13b for travel therein.

The projections 14a as well as the member 14 forming a part thereof are preferably formed of a plastic material which is sufficiently flexible and resilient e.g., polypropylene, polyethelene, etc., so that it may snap past the lip 13aa into the cavity 13a and the slots 13b. Alternatively the base member or both members may be selected of a resilient type of material to allow the members to snap together.

The member 14 is also provided with first and second bores 14b and 14c. The bore 14c is constructed so that it is positionable over the pedestal 13c and is slidably guided thereby.

In order to urge the key member upwardly as shown in FIG. 2 there is provided a resilient biasing means such as a spring 16. The spring 16 is positioned about the pedestal 13c and at one end is located in the bore 14b.

A second resilient biasing means such as a spring is shown at 16 and performs the function of urging the conductive layer 11 against the contact means 9 upon application of a force to member 14 (see FIG. 3). Each of the springs may be coil springs as shown.

The spring 16 is selected such that when it is in the position shown in FIG. 2 it applies little or no force to the layer 11 and when it is forced downwardly by the member 14 it remains virtually uncompressed (see FIG. 3) and distorts the layer 11 so that it engages the contact means 9. The spring 16 is also preferably selected such that when the layer 11 bottoms against the contact means 9, it then slightly compresses so as not to substantially injure the layer 14 surface by penetrating into it. A protective cover layer e.g., of plastic may be positioned between the spring 16 and the layer 11 to provide further protection.

The actuator 12 is preferably mounted to the board 8 by the provision of rods 13e extending from the member 13. The rods extend through the holes 8a, 10b, and 11a to join them together in a sandwich.

The rods are preferably constructed of a plastic material e.g., polypropylene, nylon which may be softened with heat to form the heads 13f. Alternatively the rods may be threaded and nuts may then be used to hold the sandwich together.

As shown in the aforementioned patent application or disclosed in the aforementioned patent applications, the contact means may be segmented and thus the layer 11 may be used to close a circuit between the segments or alternatively the layer 11 may be grounded and the contact means made high (+) so as to complete a circuit. Connector pins as shown in the aforementioned patent applications may be used to make contact with the layer 11 and the contact means 9.

Claims

We claim

1. In a keyboard or the like which includes an insulator board having electrical contact means thereon, insulator means having a window therethrough in alignment with at least a portion of the contact means and a resilient electrically conductive sheet means positioned on the insulator layer which has the property of being deformable by a force applied thereto to make electrical contact with the contact means by extending through the insulator means window and then springing back to a position out of electrical contact with the contact means, the improvement comprising a base member positioned over the conductive layer and having a portion of a movable member slidably positioned therein, first resilient biasing means positioned between the base member and the movable member to urge the movable member and the base member apart, a lip forming a part of the base member to maintain at least a portion of the movable member within the confines of the base member by entrapping projections attached to the movable member, a second resilient biasing means positioned in contact with the movable member and positioned to apply a force to the conductive sheet means to deform it in order to make electrical contact with the contact means, said base member having guide slots along the inner wall thereof in which the projections are slidably movable, in which the base member includes a pedestal and in which the movable member includes a first bore, the first bore of the movable member positioned about at least a portion of the pedestal.

2. In a keyboard as claimed in claim 1 in which the pedestal has a bore in which the second resilient biasing is positioned, said second resilient biasing means extending into the bore beyond the pedestal to engage the movable member.

3. In a keyboard as claimed in claim 2 in which the spring is of the type which will compress once bottoming the conductive layer against the contact means.

4. In a keyboard according to claim 3 in which the first resilient biasing means surrounds the pedestal.

5. In a keyboard according to claim 4 in which the second resilient biasing means rests directly on the conductive layer.

6. In a keyboard according to claim 5 in which the resilient biasing means are coil springs.

7. In a keyboard according to claim 6 in which the base member includes rods which extend through holes in the board, the conductive layer and the insulator layer to form a sandwich.