Multi-output Level Keyboard Switch Assembly With Improved Operator And Contact Structure

Abstract

A structure which includes a circuit board having a conductive pattern thereon and supporting a resilient conductive layer by way of an insulator layer having a plurality of windows therethrough in alignment with portions of the conductive pattern, the resilient layer divided into at least two sections held electrically apart by pins coupled to a frame member in which the board and layers are packaged.

Description

STATEMENT OF THE DISCLOSURE

This invention is directed to a new and improved key-board structure and is more particularly directed to a keyboard structure which is constructed to provide more than one output voltage level.

This invention is an improvement over the keyboard structure shown copending in U.S. Pat. application Ser. No. 154,752 filed June 12, 1971 by Richard E. Seeger,Jr., and William J. Lynn now U.S. Pat. No. 3,721,778.

In the past i.e., as disclosed in the aforementioned application, each of the keyboard output terminals provided the same output voltage level to represent respective key depression or switch closure. This was quite adequate as long as a single output level was all that was needed to drive digital logic circuitry or the like. But as time went on there grew the need for a keyboard to supply not only the signals for logic circuits but also some signals at much higher voltage levels to control operative or analog devices such as a servomechanism.

While there are undoubtedly many ways of converting one voltage level to another voltage level using circuitry, this would have been quite expensive. Accordingly, there developed a need for the above to be accomplished using the basics of the keyboard structure shown in the above mentioned application without substantially raising the cost of keyboard construction.

The present invention accomplishes the above multiple voltage level output requirement in a novel manner while using the basics of the prior keyboard structure with a minimum of costly modifications.

BRIEF DESCRIPTION OF THE DISCLOSURE

The keyboard of the present invention provides multiple voltage level outputs from different terminals thereof by using a multi-segment conductive layer or pad positioned on an insulator layer having a plurality of windows therethrough in alignment with portions of a conductive pattern, the segments of the conductive layer being electrically separated from each other by retaining means and in the preferred embodiment being coupled to different input or supply signal terminals. Key or switch-like members of the keyboard are depressible to force the conductive segments through selected ones of the windows of the insulator layer against portions of the conductive pattern in order to provide output signals at keyboard output terminals coupled to different portions of the conductive pattern.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of a keyboard of the present invention;

FIG. 2 is a bottom view with the parts cut away of the keyboard;

FIG. 3 is a sectional view broken at the center and taken along line 3--3 of FIG. 1; and

FIG. 4 is a sectional view taken along line 4--4 of FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Reference should now be had to FIGS. 1 to 4 for a description of the preferred embodiment of the disclosure.

The keyboard comprises a frame 10 preferably of insulator material more preferably of plastic such as A.B.S a high impact polystyrene or may be constructed of other type plastics such as polypropylene. The frame is provided with a plurality of divider members 11 which form the walls of windows 12 extending through frame.

The underside of the divider members 12 includes a plurality of rods 13 (preferably formed at the same time as the frame i.e., by molding [see FIG.2]) which extend downwardly as shown in FIG. 4. The rods 13 are preferably of the same plastic material as the frame 10 and preferably may be softened by heat to form the head 13a to hold the keyboard assembly together as shown in FIG. 4. Alternatively the rods may be threaded and nuts may then be used to hold the keyboard assembly together.

Positioned directly below the frame member 11 is a thin plastic insulator layer 14 e.g., of Mylar which has indicia applied thereto. The indicia may be marked thereon using inks or may be applied thereto using other conventional techniques.

The layer 14 is provided with a plurality of holes 14a through which the rods 13 extend to locate it within the confines of the frame.

Positioned directly below the layer 14 is a conductive plastic layer 15 which is divided into at least two segments 15a and 15b. The conductive layer is preferably of a resilient material such as plastic e.g., silicone rubber filled with 10 to 80 percent by volume of silver flakes. Rubber is defined as a plastic for the purposes of this invention.

The segments 15a and 15b are electrically isolated from each other, lie in substantially the same plane, and are preferably held isolated by at least two of the rods 13 extending through holes 15aa formed in each of the segments 15a and 15b.

Reference may be had to U.S. Pat Nos. 3, 140, 342 and 3, 576, 387 for a description of other material compositions suitable for use as the layer comprising segments 15a and 15b.

The segments 15a and 15b are positioned over an insulator plastic layer 16 e.g., of Mylar having a plurality of windows extending therethrough in line with windows 12. The rods 13 also extend through holes 16b in layer 16 to locate the layer 16 within the frame 10.

Below the layer 16 is a typical circuit board 17 e.g., of Bakelite having a plurality of conductive electrical contacts or pathways 18 formed thereon. See the aforementioned application for typical circuit patterns or pathways.

The circuit pattern may be formed conventionally from copper which is etched or by the spraying of conductive paint.

The electrical pathways are at least in part aligned with the windows 16a so that the application of a presence (by a finger) to the force applying layer 14 can push portions of the conductive layer segments through the windows 16a against the pathways 18. In this manner electrical contact is made between the conductive segments and the pathways 18. When the force is withdrawn, the resiliency of the conductive layer causes it to withdraw and spring back from the conductive layer and break contact. The rods 13 extend through holes 17a in the board to hold the assembly together.

In order to make electrical contact with the conductive segments 15a and 15b as well as the pathways 18, there are provided pins 20-30 supported in connector supports 20a-23a mounted to the board 17.

Electrical conductor pins 20 and 23 are electrically coupled directly to segments 15a and 15b respectively so that different input voltage levels may be applied to the segments e.g., + 6v to pin 23 and segment 15b and + 30v to pin 20 and segment 15a. The pins 20 and 23 are preferably enbedded in the segments 15a and 15b and extend through holes 16b formed in the layer 16.

Electrical contact is made to the pathways 18 via pins 21 and 22 as shown. The left side of FIG. 3 represents the keyboard under the indicia marking X and the right side of FIG. 3 represents the keyboard under the indicia marking O with the parts below the other indicia broken away.

Claims

What is claimed

1. In a keyboard or the like which includes an insulator board having circuit pathways thereon, insulator means having a plurality of windows therethrough in alignment with selected portions of said pathways, a resilient electrically conductive layer means positioned on said insulator and divided into at least two segments that are spaced apart and electrically isolated from each other and lie in part in substantially the same plane, each of said segments covering at least one of said windows of said insulator layer, first means for positioning and holding said segments in electrical isolation from each other, second means for applying force to push portions of said segments through said windows they overlie in order to make contact with said pathways, third means for providing electrical input signals to generate output signals represent of a force applied to said segments, a plurality of electrical signal output pins coupled to different ones of said pathways and in which the third means comprises electrical signal input pins, a different one of which is electrically coupled to each of said segments.

2. In a keyboard as called for in claim 1 in which said first means comprises a frame which has a plurality of rods extending therefrom, at least two of said rods extending through each of said segments to locate said segments with respect to each other.

3. In a keyboard according to claim 2 in which said rods extend through each of said layers and board to make a sandwich thereof.

4. In a keyboard according to claim 3 in which said frame is formed with a plurality of divider members defining windows in at least partial alignment with said windows of said insulator layer and in which said second means comprises an indicia layer of insulator material positioned between said frame and said segments, said indicia layer having a plurality of markings thereon which may be seen through said windows in said frame.

5. In a keyboard or the like comprising electrical conductive layer means divided into at least two segments electrically isolated from each other,

a plurality of electrical pathways isolated from each other,

means for retaining said segments electrically isolated from each other, insulator means for maintaining said segments electrically isolated from said electrical pathways and having windows in alignment to permit selected portions of said electrical pathways to make electrical contact with each of said segments, means for relatively moving said segments and said pathways with respect to each other in order for selected segments to make electrical contact with selected pathways through said windows, and first electrical signal pins, a different one of which is electrically coupled to each of said segments.

6. In a keyboard according to claim 5 in which second electrical signal pins are coupled to different ones of said pathways.