TECHNICAL FIELD OF THE INVENTION

The invention relates to a button and a keyboard with such button, which are used in electronic equipment for data entry, requiring keyboards.

BACKGROUND OF THE INVENTION

In the currently existing devices for data entry the buttons are usually permanently inscribed or marked with the appropriate character or function of the button. In many cases where the devices for data entry are used is necessary to change the inscription of the button. In the art this has been achieved in different ways. Widespread, for example, is by adding an additional inscription on contact-working surface of the button when it needs to make use of the second alphabet or a new function of the button.

Another known embodiment is the replacement of the entire body of a button with a different inscription which can lead to mechanical damage in the construction of the button itself or the buttons around it. Furthermore, replacement of the entire body of the button is expensive, especially when it is needed to be replaced large number or all of the buttons on the keyboard, and when necessary replacement of buttons in many keyboards.

Another popular variation is to put caps over the body of the button marked with another inscription. Such caps are known for example from patents US 5, 183,346 and US 4,755,072. These caps are pulled onto the body of the button and change its geometry, which can hinder the user when entering data. Moreover, it is more likely that these caps to be detached from the body of the button and fall off during transport or use of the keyboard.

A key for a keyboard is known from US 4100402 A comprising: a main body portion adapted to be contacted by the operator, the end of the body portion remote from the operator formed with a rear wall defining a recess into which the nail of the operator can extend and terminating in a shelf, an indicia holding plate mountable on said shelf having a pocket for accepting and holding a label with indicia thereon and an opening into said pocket to permit the label to be exchanged, the top of said plate being transparent to permit the indicia to be viewed, and mating means on said plate and said shelf for mounting the plate to the shelf. The changing of the label with indicia of this key is complicated and also the lowered position of the label toward the contact-working surface of the key hinders visibility of the label, as the label would be hidden from the user behind the key in several viewing angles.

A button is known from US 3648394 comprising: a transparent cap member having resilient latch elements extending being two oppositely disposed pairs of diverging spring fingers, a removable key identification marker and a base member securable to a keyboard keystem and having a pair of oppositely disposed recesses defined in part by oppositely disposed diverging surfaces constituting keepers, said spring fingers being removably insertable into said apertured recesses and being squeezably displaced by said keepers for releasable retainment therebetween. The construction of this button is complicated so it require complicated separate production of its elements and makes more difficult its assembling, that increases the manufacturing costs.

SUMMARY OF THE INVENTION

Task of the invention is to provide a button for a keyboard that allows in case of need quick, easy and inexpensive change the inscription on the button, which does not change the geometry of the button and does not compromising its construction and visibility of the inscription.

Another task of the invention is to provide a button for a keyboard, which interchangeable element together with the inscription on the button is securely attached to the button in order to prevent unintentional detachinging of the interchangeable element and fall off during operation or transport of the keyboard.

Another object of the invention is to provide a keyboard with the above buttons.

These tasks are achieved by designing a button for a keyboard, comprising a body of a button, a contact element with a contact layer, which contact element is located on underside of the body of a button, an elastic spring element which provides the required working stroke of the button and allowing it to return to its starting position, a detachable cap, which is attached in a demounatble manner to the upper surface of the body of the button, wherein the top surface of the detachable cap forming the contact-working surface of the button has an inscription which indicates the function of the button. According to the invention the detachable cap has a head and at least one coupling element projecting from its lower side, where said at least one coupling element is inserted into its corresponding in shape and position at least one coupling opening, which is provided in the body of the button. The body of the button is made of elastic material.

The detachable cap could be made of elastic material or of rigid material.

Here and in the entire description the term "elastic material" means resilient material capable of recovering its initial size and shape spontaneously after contraction, dilatation, or distortion.

Here and in the entire description the term "rigid material" means firm not flexible material that can not easily change its size and shape in conditions (temperature, humidity and pressure) usual for normal operation of electronic equipment with keyboards.

According to a preferred embodiment the detachable cap has an even number of coupling elements arranged symmetrically with respect to at least one plane of symmetry of the detachable cap, said coupling elements are inserted into their corresponding in shape and position of coupling openings in the body of the button.

According to a modification of the above embodiment, between at least one pair of symmetrically arranged coupling elements there is a vertical reinforcing rib and in the body of the button is provided a corresponding in shape and position groove for receiving of said reinforcing rib.

According to a preferred embodiment at least one of the openings in the body of the button is a through hole, passing from the top surface to the bottom surface of the body of the button and its corresponding oblong coupling element has at least one engaging element at its lower end in order to be engaged with a respective supporting element provided in the body of the button at the lower end of the corresponding through opening.

According to a modification of the above embodiment, the length L _e of said oblong coupling element of the detachable cap is greater than the length L ₀ of said through opening so that the lower end of the coupling element jut out from the underside of the body of the button.

It is possible that on the upper surface of the button's body to be provided a craddle that grips the head of the cap, which is formed with side dimensions and shape corresponding to said craddle.

According to another alternative embodiment the detachable cap has a peripheral edge projecting peripherally downwardly from the lower surface of the head of the cap, and the upper part of the body of the button is provided with a peripheral stepped recess corresponding in shape and size in order to receive the said peripheral edge of the detachable cap.

It is provided a base for buttons, which includes buttons for keyboard according to the present invention, which are joined to the flat main element, wherein the buttons are located on the main element in a predetermined order and joined to it by elastic spring elements. According to a preferred embodiment the main element of the base for buttons, the bodies of the buttons and the elastic spring elements are made of same elastic material as a monolithic body.

It is provided a keyboard for electronic device comprising of base for buttons according to the invention.

The advantage of the button for keyboard according to the invention is that if necessary it is ensured quick, easy, and inexpensive replacement of the inscription on the button by replacing the detachable cap of the button. The construction of the detachable cap provides a tight assembly with the body of the button, which prevents unintentional falling off of the detachable cap. While the size of the detachable cap is adapted to the size of the button, so it does not substantially change its geometry.

BRIEF DESCRIPTIION OF THE DRAWINGS

In more detail, the button for keyboard, the base for buttons and the keyboard according to the invention are illustrated by means of preferred embodiments, given as non-limiting examples of scope of the invention, with reference to the accompanying drawings, wherein:

Figure 1 is a cross-sectional view of a button with the detachable cap according to one embodiment of the invention.

Figure 2 is a perspective view from below of the detachable cap with two symmetrically arranged coupling elements.

Figure 3 is a perspective view from below of the detachable cap for bigger in size button with six symmetrically arranged coupling elements. Four of the coupling elements are provided with engaging elements. Below are shown the reinforcing vertical ribs, which are joining two pairs of coupling elements.

Figure 4 is a view from above of a base for buttons with a plurality of small buttons and one bigger button. The buttons are shown without caps, which allows the coupling openings of the detachable caps to be visible. The dotted lines show the vertical plane of symmetry of the buttons, according to which are symmetrically positioned coupling openings.

Figure 5 is a cross-section through the long side of the button according to another embodiment. The detachable cap has two coupling elements joined with a vertical rib. The coupling elements are oblong and are inserted in through openings. In the upper part of the body of the button is provided a craddle that grips sideways the head of the cap.

Figure 6 is a cross-section through a short side of the button depicted in Fig. 5. The coupling element of the cap is oblong and is inserted into the through opening.

Figure 7 shows the button from Figures 5 and 6 in perspective with detached cap. In the upper part of the body of the button is provided a craddle for the head of the cap and groove for vertical reinforcing rib.

Figure 8 is a cross-sectional view of a button according to another embodiment, with a cap which has a peripheral edge that grips completely the upper part of the body of the button.

Figure 9.1 is an exploded perspective view of the base for buttons according to one embodiment of the invention with dismounted caps. The buttons have craddle for the cap's head.

Figure 9.2 is a perspective view of the assmbled base of the buttons shown in fig. 9.1.

Figure 10.1 is an exploded perspective view of the base for buttons according to another embodiment of the invention with dismounted caps. The detachable caps have a peripheral edge in order to grip the upper part of the body of the button.

Figure 10.2 is a perspective view of assmbled base for buttons shown in Fig. 10.1. EMBODIMENTS OF THE INVENTION

A button for keyboard according to the invention (fig.1) includes: a body of the button 4, a contact element 5 with a contact layer 6, which contact element is positioned on the underside of the body of the button 4, an elastic spring element 3, which provides the necessary working stroke of the button and which allows it to return into starting position, and a detachable cap 8 which is detachably attached to the upper surface 7 of the body of the button 4, wherein on the upper surface of the detachable cap forming the contact- working surface of the button is positioned an inscription 13 indicating the button's function (see. fig. 9 and 10). According to the invention the detachable cap 8 has a head 10 and at least one coupling element 11, which projects from the lower side of the head 10, said at least one coupling element 11 is inserted into a corresponding in shape and position at least one coupling opening 9 provided in the body of the button 4.

The body of the button 4 can be of different shapes in cross section - a square, rectangular or other polygonal shape, circular or elliptical. In the preferred embodiment shown on the figures the shape of the cross section of the button is generally rectangular.

The body of the button 4 and the detachable cap 8 can be made of the same or different suitable materials, such as elastic materials, for example: TPE (thermoplastic elastomer), silicone rubber, rubber-type rubber and the like, or rigid materials, such as: ABS (acrylonitrile-butadiene-styrene), polycarbonate, polypropylene, polyethylene and the like. Preferably the body of the button 4 is made of elastic material.

In one embodiment of the invention, the detachable cap 8 is made of light conductive material, and in this embodiment the keyboard is provided with light sources and light pipes, which are conducting the light from the light source to the coupling elements 11 of the light conductive cap 8. The light conductance through the coupling elements 11 allows the illumination of the cap's head 10 and highlighting the inscription 13 on the detachable cap 8 at reduced or absence of external light.

The spring element 3 is made of an elastic material, for example: TPE (thermoplastic elastomer), silicone rubber, rubber-type rubber and the like.

In the preferred embodiments shown in the drawings, the body of the button 4 and the elastic spring element 3 are formed as one piece of the same elastic material. In this embodiment, the elastic spring element 3 is designed as a flexible membrane in the shape of a truncated pyramid extending downwards from the lower surface of the button. The elastic membrane allows the button to perform reciprocating motion in vertical direction and after removing the force on the button the elastic membrane returns the body to its upper starting position.

It is possible that the spring element is in the form of a cone, double cone, bell, dome, flat dome and others.

In the embodiments shown on the figures the contact element 5 is budlike projection with flat lower surface, which projects from the underside of the body of the button and is monolithic thereto. A contact layer 6 of suitable electrically conductive material, such as carbon black, is applied by a known manner to the lower surface of the contact element 5.

The contact layer 6 may be made of conductive carbon rubber, which joins the contact element 5 through vulcanization.

In preferred embodiments of the invention shown in the figures, the lateral dimensions of the detachable cap 8 correspond to the lateral dimensions of the body of the button 4, wherein the joining of the detachable cap 8 does not change the side geometry of the button.

As shown in figures 1 and 2, the detachable cap 8 has a head 10, and the attachment of the detachable cap 8 to the body of the button 4 is done by coupling elements 1 1 that projects from the lower surface of the cap's head 10. The coupling elements 11 are inserted into corresponding by shape and dimensions coupling openings 9 in the upper surface of the body of the button 4. For example, as shown on the figures, the coupling elements 11 can be designed as cylindrical extensions inserted into the respective cylindrical openings 9 in the body of button 4. The shape of the coupling elements in cross-section may be different, for example, truncated cone, truncated pyramid, square or other polygonal prism. Accordingly, the coupling openings may have a different shape corresponding to the shape of coupling elements.

In a preferred embodiment of the invention the coupling elements 11 are arranged with their long side perpendicular to the head of the cap 10 and, respectively, the openings 9 are arranged with their long side perpendicularly to the upper surface of the body of the button 4. It is also possible that the coupling elements 11 are arranged under a certain angle with respect to the head of the cap 10 and, respectively, the longitudinal axes of the openings 9 are arranged at the same angle relative to the upper surface of the body of the button 4.

The upper surface of the detachable cap may be horizontal, concave, convex, tilted to one side or another form that allows convenient button click.

Different embodiments of the detachable cap are possible according to the material that is made of. The material of the detachable cap could be rigid or elastic. Examples of the types of rigid and elastic materials are mentioned above.

The engaging of the coupling elements to the body of the button may also be implemented in several different ways.

In one embodiment the coupling elements of the detachable cap are designed with cross-sectional dimensions substantially identical to the inside dimension of the coupling openings in the body of the button. This allows when the coupling elements are inserted into the openings of the button's body to ensure cohesion due to frictional forces. Thus the detachable cap cannot be easily detached from the body of the button without corresponding mechanical force is applied. Depending on the material of which the detachable cap and the body of the button are made, the coupling elements size and their respective openings size must be made accordingly.

In another embodiment the coupling elements are made with smaller lateral dimensions from the openings, and the engagement can be carried out with additional engaging elements, which are provided on the coupling element and in the coupling openings, as more fully described below.

The detachable cap 8 may have one or more coupling elements 11 depending on the dimensions of the body of the button 4, which is provided with a corresponding number of openings 9 for reception of the coupling elements 11. The head and the coupling elements of the detachable cap are made of the same material and the detachable cap is one monolith detail.

In a preferred embodiment the detachable cap 8 has an even number of coupling elements 11, symmetrically arranged with respect to at least one plane of symmetry of the detachable cap. Accordingly, in the body of the button 4 are provided a an even number of openings 9 which are also arranged symmetrically with respect to at least one plane of symmetry of the body of the button.

For example, as shown in fig. 2, the detachable cap has two coupling elements 1 1 , which are arranged symmetrically with respect to a vertical plane of symmetry perpendicular to the long side of the detachable cap 8. Accordingly, in the body of the button 4 are provided two openings 9 arranged symmetrically with respect to the vertical plane of symmetry perpendicular to the long side the body of the button 4 (Fig. 4).

In Figure 3 is shown as well an example of a cap 8 for bigger in size button (see Fig. 4) with six coupling elements 11 which are arranged symmetrically with respect to two vertical, perpendicular to each other planes of symmetry. In the body of the button 4 are provided corresponding number of openings 9 also arranged symmetrically to two vertical, perpendicular to each other planes of symmetry (Fig. 4).

Different configurations of the coupling elements 11 are possible depending on the size and shape of the button and the detachable cap.

For reinforcement of the detachable cap 8 in a further preferred embodiment, shown in Figures 3 and 5 is provided a vertical rib 14, which joins the two symmetrically arranged coupling elements 11. In order to insert the reinforcing vertical ribs 14 in the body of the button 4 is provided a corresponding in shape and position groove 15 (Fig. 7).

Figure 3 shows the detachable cap 8 with three pairs of coupling elements 11 , and between the two pairs of coupling elements 11 are arranged, respectively, two vertical reinforcing ribs 14.

Different number of reinforcing vertical ribs 14 are possible with different configuration depending on the number and arrangement of coupling elements 11.

In a preferred embodiment shown in Figures 5 and 6 part of the openings 9 are through holes and pass vertically through the entire body of the button 4. In this embodiment, the respective part of the coupling elements 11.2 are prolonged (Fig. 3) so as to reach to the lower side of the body of the button or to protrude out from the underside of the button. For this purpose the length L _e of the oblonged coupling element 11.2 is equal to or greater than the length L ₀ of its corresponding through opening 9. It is possible that all the coupling elements are oblonged.

In a preferred modification of this embodiment shown in Figures 3, 5 and 6 at the lower end of the oblonged coupling element 11.2 there is at least one engaging element 12 which engages with the corresponding support element 19 provided in the body of the button 4 at the lower end of the corresponding opening 9. The engaging elements may be of different shape. For example, the engaging element 12 may be an annular, semi-spherical or spherical fillet at the end of the oblong coupling element 11.2. Accordingly, the support element 19 can be formed as an annular step or trumpet at the lower end of the through hole opening 9 (see Fig. 5). Also the engaging and the support elements may be designed respectively as a hook and notch. The configuration of the engaging element and the support element are dependent on the material from which are made the detachable cap and the body of the button.

In a preferred embodiment, shown in Figures 5, 6, 7, 9.1 and 9.2, on the upper surface of the body of the button 4 is provided cradle 16 that grips the side of the head of the cap 10. Accordingly, the lateral dimensions and the shape of the cross section of the head of the cap 10 are provided to correspond to the shape and dimensions of the said cradle 16. In this embodiment, the advantage is that during transportation and use the cap cannot be detached undesired and unexpected.

In another embodiment shown in Figures 8, 10.1 and 10.2, the detachable cap 8 has a peripheral edge 17 projecting peripherally downwardly from the lower surface of the head of the cap 10, and in the upper part of the body of the button 4 is provided a stepped recess 18 for receiving the said peripheral edge 17 of the detachable cap 8. In this embodiment, the detachable cap 8 covers the upper part of the body of the button 4, which also contributes to a more secure grip on the detachable cap 8 and prevents undesirable disassembly of the button. In the embodiment shown in Figures 8, 10.1 and 10.2, the size and shape of the lateral periphery of the head of the cap 10 corresponds to the dimensions and the shape of the side periphery of the body of the button 4. In this way, attaching of the detachable cap 8 does not change the side geometry of the button. There is a possible embodiment (not shown) in which the lateral dimensions of the head of the cap 10 is greater than the lateral dimensions of the body of the button 4, in which the head of the cap 10 projects laterally beyond the periphery of the body of the button 4.

According to the invention the base for buttons 1 includes buttons with the above construction which are attached to a main element 2 (figures 1, 4, 9 and 10). The main element can be made of rigid and/or flexible material. Examples of the types of materials were specified above.

The body of the button 4 is joined to the main element 2 by means of an elastic spring element 3 (Figures 1, 5, 6, 7, 8). The spring element may be for example membrane, which is an elastic loop with a certain height, thickness and width, extending from the base for buttons at a certain angle and joining the lower body of a button. Joining the spring element 3 to the main element 2 can be mechanically or chemically defined process - for example vulcanization.

In a preferred embodiment the main element 2, the body of the button 4 and the elastic spring element 3 are made of the same elastic material as a monolithic body, as shown on the figures.

The buttons from the base for buttons are arranged in a particular configuration in accordance with their function.

According to the invention a keyboard for an electronic device comprises of buttons with the above-described construction, arranged in a specific configuration on the said base for buttons 1 , and contact electrodes 20 positioned in the same configuration as the buttons on a carrier of the contact electrodes 21, and housing (Figure 10.1). The contact electrode serves to close the electrical circuit with its corresponding contact element of the button on the keyboard. The carrier of the contact electrode can be, for example, a printed circuit board (PCB - printed circuit board) made of glass fiber. It is possible to be applied additional layer of conductive material on the contact electrode, the same as the one on the contact element from the keyboard, for example, carbon black.

The housing of the keyboard can be independent or part of the housing of an electronic device, which the keyboard is designed for. For example, the keyboard can be a part of a cash register. The reference numbers of the technical features which are given in the claims only for the purpose to increase the understanding of the claims and therefore these reference numbers have no limiting effect in terms of the interpretation of the elements, marked with these reference numbers.