EP1962315A2

EP1962315A2 - A keyboard structure

Info

Publication number: EP1962315A2
Application number: EP08151258A
Authority: EP
Inventors: Michele Carlet
Original assignee: Check up SpA
Current assignee: Check up SpA
Priority date: 2007-02-21
Filing date: 2008-02-11
Publication date: 2008-08-27
Also published as: ITTV20070028A1; EP1962315A3

Abstract

A keyboard structure for electrical and electronic devices for civil and/or industrial uses, comprising a main body, substantially monolithic, and an actuator element positioned in a housing cavity, produced in said main body. The housing cavity is defined at least partly by a relatively flexible wall of said main body. This flexible wall is operatively associated with the actuator element so that bending thereof causes activation of said actuator element.

Description

The present invention refers to a keyboard structure for electrical and/or electronic devices for civil and/or industrial use.
As it is known, in numerous electrical and/or electronic devices a keyboard is used as peripheral unit to send control signals and/or data signals.
The market proposes different types of keyboards, very different to one another according to use and user requirements.
In "mechanical" type keyboards, a front panel made of plastic, generally polycarbonate, is fitted on a containment casing. One or more control buttons are defined on the front panel. The containment casing is fastened to a base, on which there is mounted a series of keys or movable contacts, associated with an appropriate printed electronic circuit.
The user can therefore exert pressure on each button on the front panel to activate the corresponding key or movable contact, so that it interacts with the electronic circuit, causing generation of an electronic control signal or of a data signal.
Although keyboards of this type are relatively easy to manufacture on an industrial scale, they are relatively bulky and have considerable limits of an aesthetic nature.
"Membrane" keyboards comprise a pair of sheets made of polymer material, superposed and relatively movable in relation to each other. Conductive materials are deposited on each of these sheets to produce appropriate electronic circuits, comprising one or more activation contacts. Pressure of a button of the keyboard produces a short circuit between a pair of activation contacts of two superposed sheets. This allows the aforesaid electronic circuits to generate a control signal or a data signal.
Unfortunately, membrane keyboards are characterized by the presence of a low "tactile effect" for the user. This is due to the fact that the buttons of the keyboard are activated through a very low actuation force.
Moreover, membrane keyboards are often subject to wear, particularly in the areas in which pressure is applied by the finger of the user.
In other types of keyboards, utilized in general in the domestic appliance sector, a first layer of material is thermoformed according to a certain desired shape and then inserted in a mould, into which thermoplastic material is injected to produce an injection co-moulding or overmoulding process.
With this process, also called "i-moulding", a keyboard structure is obtained comprising a containment casing having externally a series of raised domes, obtained from the first thermoformed layer, and a series of internal layers made of thermoplastic material. This casing is associated with a base on which the keys or movable contacts are mounted, each of which is positioned to correspond with a dome of the casing.
In this way, by pressing on each dome, the user causes activation of the corresponding key.
It has been found in practice that although having the undoubted advantage of providing a certain tactile effect for the user, these keyboards are relatively complex and costly to manufacture on an industrial scale. Moreover, these keyboards often also present problems of wear, above all of the aforesaid raised domes.
Other keyboards, known as "capacitive", have a much simpler structure in which there are no movable parts.
On a supporting base, there is positioned at least one sheet of plastic material, on which conductive materials are deposited to form an appropriate electronic circuit, comprising one or more electrodes. The pile of conductive sheets is covered by an outer panel.
By pressing on the outer panel, in the position corresponding to an electrode, the user causes transfer of a small electrical charge to the electrode. This transfer of charge is sufficient to cause generation of an electronic control signal or a data signal by the electronic circuit.
Capacitive keyboards have considerable advantages in terms of cost, simplicity of use and reduction in dimensions. They also have undoubted advantages of an aesthetic nature. Unfortunately, these keyboards have noteworthy drawbacks in terms of sturdiness and immunity to external environmental factors such as humidity, vapour, sudden changes in temperature, etc.
Moreover, capacitive keyboards are completely devoid of any type of tactile effect, when the user presses a button.
It has been found that these keyboards also have some drawbacks in terms of operating reliability (i.e. false activations), in particular when the keyboard is provided with only one control button.
In the practical embodiment of capacitive keyboards, it is also somewhat difficult to produce selective backlighting, in order to avoid undesirable effects of light diffusion affecting several buttons.
Finally, it is known that capacitive keyboards are relatively costly, above all if provided with only one control button. In practice, they are economically attractive only in the case in which the presence of a certain number of control buttons is required.
Patent application WO2004/088692 describes a switching unit comprising a flexible membrane and a sensor device positioned inside a measurement cavity.
The sensor supplies a signal indicative of the pressure exerted on the membrane to an electronic control unit, outside the aforesaid measurement cavity. When the pressure exceeds a predetermined threshold value, the electronic control unit generates an appropriate switching signal.
Patent application DE10103563 describes a keyboard in which a sensor, for example piezoelectric or resistive, is operatively associated with a membrane.
The sensor detects any pressure exerted on the membrane by the user. An electronic control unit generates a switching signal, if the detection signal generated by the sensor exceeds a predetermined threshold.
Simultaneously, the electronic control unit also generates an activation signal for an actuator, operatively associated with the membrane. This actuator causes vibration of the membrane, generating a tactile effect for the user.
The devices described in the aforesaid patents have relatively complex and costly structures to be manufactured on an industrial scale. Moreover, their structural complexity causes non-negligible problems of sturdiness and reliability.
Therefore, the main aim of the present invention is to provide a keyboard structure that allows the aforesaid drawbacks to be overcome.
This aim and these objects, as well as other objects that will be apparent from the description below and from the accompanying drawings, are achieved, according to the invention, by a keyboard structure according to claim 1, proposed below.
The keyboard structure according to the present invention comprises a main body, substantially monolithic, provided with a housing cavity in which at least an actuator element is positioned.
The housing cavity is defined by at least a flexible wall, which is operatively associated with the actuator element, so that bending of said wall, towards the inside of the cavity, causes activation of said actuator element.
In this way, the keyboard structure, according to the present invention, has considerable sturdiness, constructional simplicity and high immunity to external environmental factors. Moreover, it is particularly suitable for manufacture on an industrial scale, at particularly competitive costs, regardless of the number of control buttons.
Further characteristics and advantages of the present invention can be better perceived with reference to the description provided below and to the accompanying figures, provided purely by way of a non-limiting example, wherein:

Figures 1A-1B show a schematic sectional view and a schematic top view of the keyboard structure, according to the present invention; and
Figure 2 shows a more detailed sectional view of the keyboard structure, according to the present invention; and
Figure 3 shows a schematic top view of another embodiment of the keyboard structure, according to the present invention; and
Figure 4 shows a schematic top view of a further embodiment of the keyboard structure, according to the present invention.

With reference to the aforesaid figures, the keyboard structure 1, according to the present invention, comprises a main body 2, substantially monolithic.
Preferably, the main body 2 is produced from a portion of plastic material, preferably at least partly transparent, comprising a single layer of polymer material, such as polycarbonate, polyurethane or polyethylene. A layer of plastic material loaded with metal components or granules can also be utilized.
The structure 1 also comprises at least an actuator element 3, activatable by the user. The actuator element 3 can advantageously be constituted by a key or by a movable contact, or more generally by any device capable of activating an electrical circuit, following application of pressure or force.
The actuator element 3 is positioned in a housing cavity 4, produced in the main body 2 and, preferably, sealed with respect to the external environment.
The cavity 4 is defined at least partly by a wall 5 of the main body 2, which advantageously has a relatively low thickness with respect to the thickness of the main body 2, in particular with respect to the thickness of the layer of plastic material from which the main body 2 is produced.
The wall 5 is therefore relatively flexible with respect to the main body 2 and is operatively associated with the actuator element 3, so that bending thereof 100 causes activation of this element.
Preferably, the wall 5 is produced in proximity to an outer surface 21 of the main body 2. During use, this surface 21 is the one effectively accessible by the user to press the control button of the keyboard 1.
In particular, the wall 5 is positioned so that a surface thereof 51 constitutes a portion of the outer surface 21 of the main body 2.
On this surface portion 51 there is defined the pressure area relative to at least a control button 50 of the keyboard 1.
The other surface 52 of the wall 5 instead delimits at least a portion of the cavity 4.
In this way, when the user exerts pressure on the outer surface 51 (i.e. on the control button 50) the wall 5 bends towards the inside of the cavity 4, in the direction of the arrow 100, substantially orthogonal with respect to the plane of extension of the surface 21.
The surface 21 can be substantially flat, as shown in Figure 1A or, as shown in Figure 2, have a certain curvature so as to be outwardly convex, at least on the outer surface 51, in particular on the pressure area defining the control button 50.
Preferably, as shown in greater detail in Figure 2, the wall 5 has non-uniform thickness. In the peripheral regions 54, the wall 5 may be relatively thin, so as to increase the flexibility and the elastic response thereof when pressure on the surface 51 is released. This determines a greater resistance to bending of the wall 5 and allows an improved tactile effect for the user to be obtained.
It is evident how, in practice, the wall 5 behaves like a body with shape memory, capable of returning to the initial shape/position after deformation/movement to which it is subjected following pressure by the user.
Instead, on the inner surface 52 the wall 5 preferably has a ridge 55, facing the inside of the cavity 4.
The ridge 55 is advantageously positioned in the pressure area defining the control button 50, above the actuator element 3, so as to allow activation thereof with minimum bending of the wall 5.
In practice, the ridge 55 constitutes a stop element suitable to limit downward bending D of the wall 5 and to allow, at the same time, a more reliable activation of the actuator element 3.
Advantageously, the actuator element 3 is electrically connected to at least an electronic circuit 6 suitable to generate at least an electrical control signal or a data signal 62, following activation of the actuator element 3.
The signal 62 (electrical and/or RF and/or infrared) can be sent conventionally or by wireless transmission to an electrical and electronic device (not shown) connected to the keyboard 1.
The electronic circuit 6 can advantageously comprise a logic control circuit and/or a microprocessor device. The electronic circuit 6 is preferably produced as a printed circuit on a suitable supporting base 61.
The electronic circuit 6 and the relative base 61 are housed inside the cavity 4, so as to ensure greater compactness of the structure 1.
To obtain backlighting of the control button 50, corresponding to the actuator element 3, the housing cavity 4 preferably houses electronic lighting means 7, 7A, 7B, which are preferably controlled by the electronic circuit 6.
Preferably, as shown in Figure 2, the electronic lighting means comprise at least a first electronic lighting device 7A, such as a LED (Light Emitting Diode) device, fastened to the base 61 of the electronic circuit 6, so as to direct the light radiation substantially upwards, in the direction of the wall 51 (arrow 71).
Preferably, the electronic lighting means comprise also at least a second electronic lighting device 7B, for example a LED device, fastened to the base 61 of the electronic circuit 6, so as to direct the light radiation sideways, towards the outside, substantially parallel with respect to the wall 51 (arrow 72).
In this way, differentiated lighting of the control button 50 and of the peripheral side regions of the main body 2 can be ensured.
In Figures 1-2, the main body 2 of the structure 1 comprises a single housing cavity 4 suitable to house a single actuator element 3. In this case, therefore, the keyboard structure 1 is produced so as to comprise a single control button 50.
The cavity 4 could however comprise several actuator elements 3. In this case, the keyboard structure 1 could comprise, obviously, one or more control buttons 50, each of which usable by the user to activate one or more actuator elements 3. Figure 3 shows the case in which several actuator elements 3, housed in a single cavity 4, correspond to a single control button 50, of the joystick type.
Alternatively, the main body 2 could comprise several housing cavities 4, each of which is suitable to house one or more actuator elements 3 (figure 4). According to this embodiment, the keyboard structure comprises, obviously, a plurality of control buttons 50.
In other words, therefore, the keyboard 1 can comprise one or more housing cavities 4, each of which can comprise one or more actuator elements 3 and/or one or more printed circuits 6 and/or one or more electronic lighting devices 7. One or more actuator elements 3 can correspond to each control button 50 of the keyboard.
The keyboard structure 1, according to the present invention, is easy and practical to manufacture on an industrial scale, regardless of the number of control buttons provided.
A preferred process for manufacturing the structure 1 can comprise a first step to produce a main body 2 from a single-layer portion of plastic material, optionally loaded with metal components or granules.
This is advantageously followed by a second step to produce at least a housing cavity 4 in the main body 2, defined at least partly by a relatively flexible wall 5, which is produced in proximity to an outer surface 21 of the main body 2.
The steps described above can be implemented practically through simple injection moulding and/or turning operations of plastic materials.
A third step of this preferred process involves positioning at least an actuator element 3 in the housing cavity 4, so that bending 100 of the wall 5 towards the inside of the housing cavity 4 causes activation of the actuator element 3.
Preferably, there are also provided a fourth step to position, in the cavity 4, at least an electronic circuit 6, operatively associated with the actuator element 3, and a fifth step to position, again in the same cavity 4, the LED devices 7A-7B, oriented so as to direct the light radiation according to the directions described above.
It has been seen in practice that the keyboard structure 1, according to the present invention, allows the proposed aim and the objects to be fully achieved.
The keyboard structure 1 is particularly sturdy and constructionally simple. This makes it particularly suitable for any access control system, above all for outdoor and/or vandal-proof use.
Incorporation of the actuator element 3 inside the main body 2, substantially monolithic, ensures high immunity of the structure 1 to external environmental factors, such as the presence of high levels of humidity or vapours.
The structure 1 is substantially immune to false activations, also in the case of complete immersion in a liquid.
This makes it particularly suitable to control electronic devices in a domestic environment, such as electronic suction devices, to regulate the operation of showers, whirlpool baths or other appliances for use in the bathroom.
The constructional simplicity of the structure 1 also allows easy integration thereof in control panels, with considerable reduction of dimensions and a pleasing external appearance. For example, the structure 1 can easily be associated with the surface of a control panel or, preferably, be housed in a cavity thereof, to offer the user a substantially smooth surface, without connecting edges between different layers of material.
This makes the structure 1 particularly suitable for use in control units integrated in furnishing accessories, or in control units of electronic devices for light and sound diffusion. The main body 2 intrinsically ensures efficient electrical insulation of any live parts, given that the user cannot access the inside of the cavity 4.
The structure 1 is therefore particularly suitable for use in electrical switches, above all in a domestic environment, to replace the conventional mechanical switch. Moreover, due to the presence of the actuator element 3, substantially of mechanical type such as a key or movable contact, the structure 1 has a noteworthy tactile effect, easily perceptible by the user, when a button 50 is pressed.
This fact makes the structure 1 particularly suitable for use in electrical or electronic devices in noisy or industrial environments, in which it is necessary for the user to be aware that a control button has been activated.

Claims

A keyboard structure (1) for electrical and electronic devices for civil and/or industrial uses characterized in that it comprises a main body (2), substantially monolithic, and at least an actuator element (3) positioned in a housing cavity (4), which is obtained in said main body, said housing cavity (4) being defined at least partly by a relatively flexible wall (5) of said main body, said flexible wall being operatively associated with said actuator element so that bending (100) of said flexible wall causes activation of said actuator element (3).
A keyboard structure according to claim 1, characterized in that said flexible wall is produced in proximity to an outer surface (21) of said main body, so that a surface (51) of said flexible wall (5) constitutes a portion of said outer surface (21).
A keyboard structure according to claim 2, characterized in that bending of said flexible wall takes place substantially in a direction (100) orthogonal with respect to the plane of extension of said outer surface (21), towards the inside of said housing cavity (4).
A keyboard structure according to one or more of the preceding claims, characterized in that said actuator element (3) is operatively connected to at least an electronic circuit (6) suitable to generate at least an electrical control signal (62) following activation of said actuator element, said electronic circuit being housed in said housing cavity.
A keyboard structure according to one or more of the preceding claims, characterized in that said housing cavity houses, at least partly, electronic lighting means (7) said electronic lighting means comprising at least a first electronic lighting device (7A) suitable to direct light radiation substantially in the direction (71) of said flexible wall and at least a second electronic lighting device (7B) suitable to direct light radiation outwards, substantially in a direction (72) parallel with respect to said flexible wall.
A keyboard structure according to one or more of the preceding claims, characterized in that said main body comprises a plurality of said housing cavities (4), each of which is suitable to house one or more of said actuator elements (3).
A keyboard structure according to one or more of the preceding claims, characterized in that said flexible wall has non-uniform thickness.
A keyboard structure according to one or more of the preceding claims, characterized in that said main body is produced of a plastic material, at least partially transparent.