JPS5935489B2 - key switch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a key switch used in a keyboard device or the like, and is particularly characterized by a rubber spring that performs a key action function of the key switch.

In general, various key switches used in keyboard devices used as input devices for computers and cash registers, etc., are durable for long-term use, provide a comfortable feeling to the operator, and are inexpensive enough to be mass-produced. The realization of this is largely due to the spring member responsible for the key action action.

However, metal springs, which are the most commonly used spring members at present, suffer from a lot of wear from a material standpoint when used continuously and frequently, and are susceptible to rust and corrosion caused by the environment in which they are used. This has the drawback that it is easy to cause accidents such as changes in spring characteristics and breakage, and it is inevitably expensive to obtain high quality products.In addition to these, in recent years, key switches for calculators, etc. Rubber springs made of rubber or polymer materials have become popular as so-called low-grade products that solve the above-mentioned cost disadvantages, but these are not designed for cost-effectiveness. Wow, there is a strong tendency that the aspects necessary for comfortable key operation, such as the proper key stroke and constant pressing force that are originally required for key switches, are completely neglected, and there is a strong tendency for cost and durability to be neglected. The reality is that we have not yet achieved a high quality product that takes full advantage of its superiority over metal springs in terms of materials, such as its rich spring properties.

Under these circumstances, the present invention aims to achieve advantages in cost and durability similar to so-called low-grade products used in conventional electric music by using rubber or an elastic polymer material. The present invention aims to create a rubber spring that is superior to metal springs in terms of comfortable key operation by devising its structure while maintaining the same characteristics, and to provide a key switch using such a rubber spring.

Hereinafter, the present invention will be explained in detail with reference to the drawings. FIG. 1 shows a longitudinal sectional view of a key switch according to the present invention, in which 1 is a key button that is directly pressed by a finger, 2 is a key stem attached to the lower part of the key button, and these key buttons 1 and the key stem are shown in FIG. 2 and an operating member are constructed.

3 is a key guide placed on a substrate 4 to guide and support the vertical movement of the key stem 2; 5 is this key guide 3;
Accommodated in the lower space of? The protrusion 5a on the upper surface is an inverted cup-shaped rubber spring that is fitted into the hole 2a formed in the lower part of the key stem 2, and is made of rubber or an elastic polymeric material. It is responsible for the action.

Reference numeral 6 denotes a layered soft elastic material such as a sponge attached to the inner upper surface of the inverted cup shape of the rubber spring 5, and a conductive film 7 as a movable contact is attached to the lower surface of the rubber spring 5. The conductive film 7 is coated with an electrically insulating material and electrostatically faces the two fixed contacts 8, 8 arranged on the substrate 4, and the conductive film 7 is at a distance from the two fixed contacts 8, 8. By changing the capacitance between the two fixed contacts 8, 8, the key switch having the above configuration is a so-called non-contact type capacitor switch.

FIG. 2 is a sectional view for explaining in detail the shapes and mounting positions of the rubber spring 5, layered soft elastic body 6, and conductive film 7, which are the main parts of the key switch shown in FIG.

As is clear from the figure, the rubber spring 5 has a relatively thick film thickness at the upper pressing operation part 51 where the projection 5a is provided, and it remains flat even when a predetermined amount of pressing load is applied. The upper surface thereof is flat except for the protruding portion 5a, and corresponds to the lower surface of the key stem, and is continuous with the outer surface of the wall portion 52 at an obtuse angle. has a planar shape at a position that protrudes further downward than the connecting portion of the wall portion 52, and the layered soft elastic body 6 is adhered thereto. The wall portion 52 has a thickness of approximately 0.3 mm or less so as to be easily bent (by the pressing load applied to the pressing operation portion 51), and each portion thereof will be described in more detail. The outer surface has a spherical shape with a lower diameter larger than the upper part and protrudes outward, and the inner surface has a conical hole shape (straight cross section) at the upper part and a sphere whose lower part is in contact with this conical hole. As a result, this wall portion 5 is formed so as to have a face hole shape (arc shape in cross section).
The upper part 52a of 2 has a somewhat thicker film thickness at the middle part,
the slope is substantially smaller than the slope of the lower portion 52b;
The connection portion 52c between these two parts, that is, the position where the conical hole portion and the spherical hole portion mentioned above are in contact, is relatively thinnest, approximately 0.150]01, and is located at the lower center of the wall portion 52. A conductive film 7 is attached to the lower surface of the pressing operation part 51 via a layered soft elastic body 6 so as to be located at
It is set to be somewhat higher than the current position. 5
Reference numeral 3 denotes a base part that is connected to the lower part 52b of the wall part 52 and supports the entire rubber spring 5 on the substrate 4. A notch 53a for adjustment is provided.

Next, the operation of each part of the rubber spring 5 having such a structure will be explained with reference to the operation state diagram shown in FIG. 3.

FIG. 3a shows the state when no pressure is applied, and FIG. 3b shows the state immediately after the start of the pressing operation. Comparison of both figures 9. Immediately after the start of pressing, the rubber spring 5 has the connection portion 52 which has the thinnest thickness among the wall portions 52 that receive the pressing load.
c is deformed so as to bulge outward, and
When the upper part 52a and the lower part 52b have a substantially linear cross-section (as in the state shown in FIG. 3b), and the load is slightly increased in the state shown in FIG. The phenomenon of inward deflection of the upper portion 52a and the lower portion 52b progresses, and immediately after this, a so-called click point is reached where the load condition is reversed. That is, when the load increases continuously from the state shown in FIG. 3b to the state shown in FIG. 3c, the upper portion 52a acts to press the lower portion 52b laterally via the connecting portion 52c. On the other hand, the lower part 52b receives a lateral elastic resistance and receives a force that causes it to bend inward, and in connection with this, the connecting part 52c bulges outward. As a result, the mechanical balance between the upper portion 52a and the lower portion 52b collapses, and most of the pressing load is directed to the object for bending the upper portion 52a and the connecting portion 52c. This click point is necessary to give the key switch a suitable operating feel. . The state immediately after this click point is as shown in FIG. 3d, and as is clear from the figure, the connecting portion 52c bulges outward (and the lower portion 52b bends inward).
has returned from the extreme state, and is now in a state where only the bending phenomenon of the upper portion 52a and the connecting portion 52c is allowed to proceed, and furthermore, the conductive film 7 on the lower surface of the layered soft elastic body 6 has reached the height of the lower surface of the base portion 53, i.e. It has reached the position where it contacts the fixed electrodes 8, 8 of the substrate 4. FIG. 3e shows a pressing operation limit state in which the pressing operation part 51 is further pressed in this state, and in this state, each bending state of the connecting portion 52c and the upper portion 52a progresses, and the upper portion The part 52a is completely buried between the lower part 52b and the pressing operation part 51 (9, and the lower part 52b is in a substantially vertical state), and the layered soft elastic body 6 is further compressed, and the conductive film 7 is It comes into close contact with the fixed electrodes 8, 8 through the coated insulating material. When the pressing load is released in the state shown in FIG. 3e, the rubber spring 5 returns to its original state in the completely reverse order due to its own elastic restoring force. In addition, to provide a supplementary explanation of the action of each part of the rubber spring 5 during the above-mentioned operation, since the lower part 52b has a larger inclination than the upper part 52a, the lower part 52b deforms extremely in response to the pressing load. The fact that the upper part 52a can be supported via the connecting part 52c without any distortion, that the corresponding slope of the upper part 52a is small, and that the thickness of the film in the middle part is relatively thick prevents deformation due to load. It is effective in that it is easy to receive damage and increases resilience.

Furthermore, since the upper portion 52a is bent and has flexibility, it can be easily deformed when the key button 1 is pressed. Since it is also distributed to 52a, the rubber spring 5
The fatigue resistance of the key button 1 can be improved and its lifespan can be extended.In addition, since the upper portion 52a can accumulate stress within its deformable limit when the key button 1 is pressed, the key button 1 can be deformed accordingly. The stroke amount can be increased to improve operability. Furthermore, the reason why the film thickness of the connecting part is made the thinnest and its position is at the lower center of the wall part 52 is that the click point to realize a smooth key action is fixed at a predetermined position, that is, the conductive film 7 is fixed. Contact 8
. The film thickness is 0.31n or 0.151n, which is used to connect each part as a whole.
These values are the limit values for producing the same quality in large quantities.
The load-stroke characteristic curve diagram for the pressing operation of the rubber spring 5 as described above is shown in FIG.

In the figure, the solid line indicates the characteristic curve of only the rubber spring 5, the dotted line indicates the characteristic curve when the layered soft elastic body 6 is included, and a-e indicate the characteristic curve for each operating state in FIG. handle. Moreover, the one shown by the one-dot chain line is an example of a key spring member which is not preferable because the lowest load point Min is formed before the pressing operation limit position Max, so the return speed is slow. Note that even in the case where the layered soft elastic body 6 of this embodiment shown by the dotted line is included, the lowest load point is formed just before the pressing operation limit position, but this is because the load itself is large and therefore Since the resistance against the load is large, the return speed does not decrease. As detailed above, in the key switch according to the present invention, the rubber spring is made of rubber or an elastic polymer material, which makes it superior to metal springs in terms of cost and durability. In terms of shape, the outer surface of the wall has a spherical shape with a larger diameter from the top to the bottom and protrudes outward, and the inner surface of the wall has a conical hole shape in the upper part and a spherical shape in the lower part. The wall portion is formed in a planar hole shape so that the lower portion thereof has a substantially larger inclination than the upper portion of the wall body, and furthermore, the connecting portion between the upper portion and the lower portion has the thinnest thickness, and It is located at the lower center of the wall, providing a highly durable and comfortable key operation feeling that has not been seen in conventional rubber springs. If the thickness of the film is 0.3m or less, and if the film thickness is about 0.1501 in the part where the film thickness is particularly thin and the bending is large, then the life expectancy of this type of rubber spring can be extended to 20 to 30 million cycles, which was previously thought to be the lifespan of this type of rubber spring. This is a major update to the test, and this film thickness value is sufficient for manufacturing high-quality products in large quantities. A conductive film is pasted through the body, and the position of the conductive film is correlated with the height of the thinnest part of the wall part that determines the click point, so that the layered soft elastic body forms a layer with the click point as the boundary. If the switch is rapidly compressed, the key action will be smooth and the chattering phenomenon of a capacitor switch can be prevented, and the industrial effect of the present invention is extremely large.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of a condenser switch according to the present invention, FIG. 2 is an enlarged vertical cross-sectional view of its rubber spring, and FIG.
The figures are diagrams showing each pressing operation state of the rubber spring, and FIG. 4 is a load-stroke characteristic curve diagram of the rubber spring. In the figure, 1 is the key button, 2 is the key stem, 3 is the key guide,
4 is a substrate, 5 is a rubber spring, 7 is a conductive film,
8 is a fixed contact, 51 is a pressing operation part, 52 is a wall part, 52
52b is the lower part, 52c is the connecting part, and 53 is the base part.

Claims (1)

[Scope of Claims] 1. A rubber spring having a fixed contact formed on a substrate, a movable contact arranged opposite to the fixed contact, and a rubber spring placed on the rubber spring and guided and supported in the vertical direction by a key guide. an inverted cup-shaped spring having a thin film-like wall portion between an upper pressing operation portion and a lower base portion, the rubber spring being made of rubber or an elastic polymeric material; The outer surface of the wall has a spherical shape with a lower diameter larger than the upper part and protrudes outward, and the inner surface of the wall has a conical hole shape in the upper part and a conical hole shape in the lower part. A spherical hole in contact with the conical hole is formed so that the lower portion of the wall portion has a substantially larger inclination than the upper portion, and the upper portion of the conical hole shape is further provided with flexibility. At the same time, the thickness of the connecting part between the upper part and the spherical lower part is formed to be the thinnest, and that part is located at the lower center of the wall part, so that the pressing operation part is pressed. A key switch characterized in that the conical hole-shaped upper portion is bent to relieve stress concentration on the connecting portion. 2 The rubber spring has a wall thickness of approximately 0.
．． 3mm or less, and the film thickness of the connecting part is 0.15
The key switch according to claim 1, characterized in that the key switch has a diameter of about mm.