JPH01209616A - Keyboard switch - Google Patents

Abstract

PURPOSE: To improve a venting method of a keyboard by letting air in a dome move into a channel when the dome is pressed. CONSTITUTION: When a dome is pushed down by finger pressure, a conductive layer 22 on the back side of the dome makes contact with a switch area of fingers 17 and 17A to be coupled together on a printed circuit. At the same time, air present under the dome is let pass through an opening 14A to enter a cannel 14, and hence the air can be dispersed through a channel system. Then a spacer seat 18 is provided to increase a travelling distance when the dome is crushed. This creates a good 'feeling' in n user who operates a key.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a keyboard system. More particularly, the present invention relates to a keyboard system for an electronic device such as a computer.

BACKGROUND OF THE INVENTION Many keyboard systems exist for use in various types of electronic devices, such as computers. Some of these keyboards that are included in some portable calculators are
A dome sheet is used on the printed circuit. This printed circuit is mounted on a relatively rigid 15a.

The dome sheet includes a plurality of domes in a predetermined pattern that matches the pattern of switch placement on the printed circuit. When the dome is pressed down (squashed) with finger pressure, a corresponding connection is made to the switch below the printed circuit.

This can be done by direct finger pressure on the dome or by applying finger pressure to a key button located on the dome.

Air is trapped under each dome as the parts are clamped or glued together during manufacturing. This air pushes down (crushes) the dome when you hit the key.
It must be removed in such a way that it can be done. This venting is also necessary to equalize air pressure (inside and outside the dome). This is necessary when the atmospheric pressure changes due to changes in altitude, such as when used in an airplane, for example. Venting prevents mushininess and improves the tactile feel when pressing keys.

Conventional keyboards of this type had a spacer sheet between the dome sheet and the printed circuit.

A series of holes were die cut into the spacer sheet to allow air to exit from under the dome when it was crushed.

However, on large multi-key keyboards, the presence of many holes makes the spacer sheet brittle and difficult to handle and assemble with other components.

Another type of keyboard used is the fl
Includes a membrane switch that includes spaced apart parallel conductors.

An electrical connection is made when the top conductor is deflected downward into contact with the bottom conductor. Any air present between the two conductors must be evacuated to prevent failure of the key operation.

(Problems to be Solved and Means for Solving) The present invention:
For example, the purpose is to propose a system that improves the keyboard venting method used in computers.

In order to achieve the above object, the following improved keyboard is provided in an embodiment of the present invention.

(a) a rigid base member having an upper surface and a plurality of channels; (b) an electrical conductor on a support carried by the upper surface of the base member defining a plurality of open switches in a predetermined pattern of switch areas; circuitry; (C) a keyboard comprising flexible, resilient domes covering said circuitry and matching switch areas of said pattern, the underside of each dome being deflected downwardly relative to said circuitry; Said keyboard including a conductive surface capable of completing an electrical connection at the switch.

Each switch region connects to at least one channel such that when the dome is deflected downwardly, air beneath the dome is admitted to one of the channels.

By providing channels in the lower surface of the base member, there is no need to sharply cut the spacer sheet. The spacer sheet can also be omitted if desired. Even if a spacer sheet is used, there is no need to drill holes in it.

In another embodiment, the electrical circuit includes a membrane switch consisting of spaced parallel conductors in each switch region. When the upper conductor is deflected into contact with the lower conductor, air present between the two conductors is forced through the apertures and into the channels of the base member.

If desired, key buttons may be placed on each switch area. In this case, acupressure is applied to the key button.

Other advantages of the venting system of the invention will become apparent from the following description of an exemplary embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The drawings illustrate an embodiment of a keyboard of the type useful in, for example, a portable calculator or any electronic device that includes a switch or keyboard.

The keyboard has a rigid base 8 material 12 made of metal, plastic, etc., for example.

It is constant in size but may vary in thickness as long as it retains its shape and provides a solid support.

Base member 12 includes a pattern of channels 14 that are all interconnectable to provide a path for air movement when the dome is collapsed as described in detail below. Each switch position on the printed circuit communicates with at least one such channel. All channels may be interconnected if desired. The channels may vary in cross-sectional shape as long as air can flow through them when the dome is collapsed.

When there is no venting to the atmosphere, it is desirable to have at least three switch areas in communication with a single channel in the base member so that when the dome is pushed down to actuate the switch, one of the switch areas It becomes possible to scatter the air appropriately. Of course, by increasing the volume of each channel, it is easier to vary the degree of air compression when a single switch is actuated.

As another alternative, the base member may include a chamber into which air is admitted when the switch is actuated.

However, this is not satisfactory if the pace member is thin.

As shown, channels are provided on the upper surface of the base member. The channels can also be located below the top surface as long as there is a suitable opening communicating between each switch region and the channel.

The printed circuit includes a thin dielectric layer 16 in which the necessary conductive paths are placed. The thickness of layer 16 may vary, but is preferably thin and flexible. Each switch area has
There may be a plurality of interdigitated spaced fingers (fingers>17.17A) as shown in FIG.

The width of each such finger may vary, but typically
It is approximately 0.005 to 0.020 inches (1 inch is 2.54 centimeters). Similarly, the spacing between adjacent fingers may vary, but is typically on the order of 0.005 to 0.020 inches.

Other conductor arrangements may be used in each switch region.

There need only be two or more spaced apart conductors that complete electrical contact when contacted with another conductor. For example, the conductors may be in a parallel spaced arrangement, a helical arrangement, etc. If desired, 3
A pole switch may also be used.

Preferably, a spacer member 18 is provided over the printed circuit. The spacer may be in the form of a sheet having a uniform thickness and having apertures or cutouts in a pattern that matches the positions of the switches.

The spacer member is preferably a dielectric material and preferably has a thickness on the order of about 0.005 inches. Typical t;
The spacer material is a polyester film (this can be either rigid or flexible). Also, the spacer 8 material may be electrically conductive as long as it is electrically insulated from the printed circuit.

A dome sheet 20 is placed on the spacer member. This sheet includes a pattern of raised domes 24 that match the switch areas of the printed circuit. When the sheet is a dielectric material, a thin conductive layer (rf!>2
Contains 2. For example, layer 22 is made of polymeric material (polymer
Conductive ink or conductive particles can be included in the merized coat+ng).

When the sheet is plastic, each dome can be formed into a dome sheet, for example by heat and pressure.

The dome sheet is flexible and elastic, and can be crushed with finger pressure from each dome, and when the finger pressure is removed, it returns to its original shape and position 5).

The dimensions of each dome are typically the same. Each dome is preferably circular and approximately 0.25 inches in diameter.

Of course, other dimensions may be used for the misfire.

Using acupressure, the dome was pressed down as shown in Figure 2 (
When collapsed), the conductive layer 22 on the underside of the dome contacts the mating fingers 17.17A on the printed circuit in the switch area. At the same time, air present below the dome is forced through opening 14A and into channel 14. This allows air to dissipate through the channel system. If desired, a vent 14B may be provided to communicate the channel 14 with the atmosphere, as shown in Figure 1g5.

However, this is not essential and moisture can also get into the keyboard.

Spacer sheet 18 is optional. However, it is better to exist because the distance the dome moves when crushed increases. This gives the user a good "feel" of the keys being operated.

The dome may be integral with the seat, as shown, or it may be a separate piece positioned over and consistent with the switch area. The dome sheet may be dielectric (eg, plastic) or a thin metal sheet (eg, cold rolled stainless steel). Another alternative may include strips each having a plurality of domes.

The dome sheet may be glued to the top of the circuit (or to the top of the spacer if present) or clamped in place.

FIG. 6 shows another embodiment of the keyboard of the present invention, which includes spaced apart parallel conductors 34, 35 as membrane switches on the base member 37. A spacer portion 33 is arranged between the conductors 34, 35 except in the switch area. A spacer member 32 is placed between the dome sheet and the upper R conductor 34 except for the switch area, and the dome 31 is
A dome sheet 31 having A may be placed on the structure.

The upper surface of the base member has a lower conductor (opening 36 at t35).
It includes a channel 36 which communicates with the space between the conductors 34, 35 via A. This allows air between the conductors to escape and enter channel 36 when conductor 34 is deflected into contact with conductor 35 to actuate the switch. If desired, conductor 34 may include an opening that allows air underneath the dome to enter the channel when the dome is depressed (collapsed).

Layers 34,35 are thin and may be metal, plastic or other dielectric material with conductive material on opposite sides of the layer.

The dome sheet 31 may be made of metal or plastic. The bottom S of dome 31A need not be conductive since an electrical connection to the switch is made when layer 34 contacts layer 35.

FIG. 7 shows another embodiment of a keyboard 40 of the present invention that includes a membrane switch. One such membrane switch is shown. It comprises spaced parallel layers separated by spacer members 41 except in the switch region. Top B
When layer 42 is pressed down into contact with layer 43, 2
The air present between the two layers is ejected through the layer 430 opening 46A and channels 4 on the upper surface of the base 444.
It can be placed in 6. If desired, the channel may communicate with the atmosphere.

Other variations are possible without departing from the scope of the invention.

(Effects) Since the present invention is configured and operates as described above, it is possible to provide a keyboard switch that can solve the above problems.

[Brief explanation of the drawing]

The drawings relate to an embodiment of the present invention, and FIG. 1 is a cross-sectional view of a keyboard switch according to the embodiment, FIG. 2 is a cross-sectional view showing the keyboard switch in FIG.
V is the plane of contact 17.17A of the switch in Fig. 1, Fig. 4 is a plan view showing the interconnection of air channels in the keyboard switch, and Fig. 5 is a plan view showing the interconnection of the air channels in the keyboard switch. A sectional view of a keyboard switch according to an embodiment, Section 6 and FIG. 7 are sectional views of a keyboard switch according to another embodiment using a membrane switch.

Claims (1)

[Scope of Claims] 1. A base member having a channel provided from the top surface, a circuit board supported by the base member and provided with opening contacts of a plurality of switches, and a circuit board having elasticity located corresponding to the opening contacts. A keyboard switch comprising: a dome made of a material and having an electrically conductive inner surface, such that when the dome is pressed, air within the dome moves into the channel. 2. The keyboard switch according to claim 1, wherein the channel has a ventilation hole communicating with outside air. 3. The keyboard switch of claim 1, wherein the channels are interconnected.