Keyboard of a home communication system

Abstract

Backlit keyboard (2, 10) of a home communication system, with a piezo-sensitive key sensor (8), with at least one at least partially transparent key body (9), with a light distribution plate (4) which is arranged between the key sensor (8) and the key bodies (9), with a diffuser film which is arranged in front of the light distribution plate (4) and behind the key bodies (9), wherein the diffuser film (7) has a first area (T1) of first translucency and a second area (T2) of second translucency.

Description

AREA OF INVENTION

[0001] The present invention relates to a backlit keyboard for a home communication system. TECHNICAL BACKGROUND

[0002] A keyboard is an input device that uses a number of keys to be pressed with the fingers. Keyboards for home communication systems come in a wide variety of designs. Illuminated keyboards for home communication systems are a particularly visually appealing option. These illuminated keyboards can be implemented in many different ways, depending on the operating principles they are based on.

[0003] One known design of such a keyboard is based on piezo-sensitive keys. An illuminated light diffuser plate is positioned in front of this piezo-sensitive keyboard, facing the key surface. The individual keys of the keyboard are thus backlit, which is particularly appealing due to the uniform light distribution. However, this arrangement has the disadvantage that the pressure applied to a particular key must be relatively high to cause sufficient deflection of the light diffuser plate and thus trigger a defined response from the piezoelectric sensor located behind the light diffuser plate, specifically assigned to that particular key. This creates the risk of so-called crosstalk. Crosstalk refers to the activation of a piezoelectric sensor adjacent to the pressed key, i.e., another key that has not been pressed and therefore should not be responding.This can result in incorrect keystrokes. This is a situation that needs to be improved.

[0004] German patent DE 20 2011 105 529 U1 describes a box structure comprising a substrate, a light guide structure, and a key structure. The light guide structure is positioned between the box structure and the substrate and has a microstructured area on its substrate-facing side, which serves to reflect or diffract the light in order to emit it from the light guide structure.

[0005] EP 0 749 138 A1 describes various types of touch panels, mentioning that a touch panel can also be of a piezoelectric type, without providing a specific embodiment in EP 0 749 138 A1.

[0006] US 2010 / 0 052 880 A1 describes a keyboard for a mobile phone with a capacitive touch sensor.

[0007] US 2012 / 0 020 045 A1 describes a portable electronic device with a waterproof keyboard. In one embodiment, the keyboard assembly comprises an embossed keyboard with a top and a bottom surface, wherein the embossed keyboard has a plurality of embossed keys on the top surface; a capacitive sensor layer located beneath the bottom surface of the embossed keyboard; and an actuator located beneath the capacitive sensor layer, movable between a first position in an unactuated state and a second position in an actuated state. SUMMARY OF THE INVENTION

[0008] Against this background, the present invention aims to provide a backlit keyboard for a home communication system, in which the risk of crosstalk between the sensors is avoided in particular.

[0009] According to the invention, this problem is solved by an illuminated button with the features of claim 1.

[0010] Accordingly, a backlit keypad for a home communication system is provided, with a piezo-sensitive key sensor, with at least one at least partially transparent key body, with a light distribution plate arranged between the key sensor and the key bodies, with a diffuser film arranged in front of the light distribution plate and behind the key bodies, wherein the diffuser film has a first area of ​​first translucency and a second area of ​​second translucency.

[0011] The underlying idea of ​​the present invention is to provide a light distribution plate with recesses and to compensate for the resulting areas of differing light scattering by means of a diffuser film with areas of varying translucency. These recesses make it possible to apply only light pressure to the buttons, since the piezoelectric sensor can be activated through the recess without having to deform the light guide plate. This greatly improves ease of use and significantly reduces crosstalk sensitivity, ideally eliminating it entirely.

[0012] However, the recess creates a different refraction of light compared to the surrounding areas of the light distribution plate. Without a diffuser film according to the invention, the areas of an illuminated key located in the region of differing refraction are backlit more brightly or darkly than the remaining areas of the key. According to the invention, the diffuser film neutralizes this difference in refraction, making it imperceptible from the outside. Advantageously, the translucency of the diffuser film is lower in brighter areas and higher in darker areas to create a brightness balance and thus homogeneous illumination or backlighting of the key. Therefore, the present invention provides a keyboard with high-quality optics, high operational reliability, and high user comfort.

[0013] Advantageous designs and further developments result from the further sub-claims as well as from the description with reference to the figures in the drawing.

[0014] According to an advantageous embodiment, the light distribution plate has recesses in which key plungers are provided. Each key plunger is arranged and designed such that it is operatively connected to the key body and the key sensor and that it transmits a mechanical actuation of the key body to a predetermined area of ​​the key sensor. Advantageously, the key plunger is adapted to the geometry of the recess so that it is guided by the recess. For example, the recess is designed as a bore and the key plunger is bolt-like, in particular with a plunger adapted to a sensor of the key sensor.

[0015] According to another embodiment, the transition between the first and second areas of the diffuser film is smooth and features a continuously changing translucency. Alternatively, the transition can also be sharp, particularly if the light edge to be masked is also sharp. The transition between the areas is thus always adapted to the characteristics of the light source to be masked.

[0016] In preferred embodiments, the diffuser film is designed as a printed film. The different translucencies in the first and second areas are achieved by different printing on the diffuser film. Optionally or additionally, the printing can also have different reflectivity or transmittance values. Thus, the light that is not transmitted through the less translucent areas of the diffuser film can be backscattered and therefore still used to backlight the key.

[0017] According to a particularly advantageous embodiment, the key plunger is at least partially transparent, and in particular completely transparent or crystal clear. Thus, it has a predetermined translucency, thereby preventing the formation of a dark spot.

[0018] In some embodiments of the invention, the translucency of the key plunger and / or the light guide properties, as well as the translucency properties of the light diffuser plate, are achieved by manufacturing the key plunger and / or the light diffuser plate from a plastic, in particular polymethyl methacrylate (PMMA). This material is also known as acrylic or Plexiglas. Especially in its "crystal clear" or "completely transparent" form, PMMA provides the desired optical properties. Furthermore, due to its thermoplastic properties, it is easy and inexpensive to manufacture.

[0019] In preferred embodiments, the second area has a lower translucency than the first area and is located in the region of the recess and / or the key plunger. This is particularly advantageous if, due to the refractive index of the material used and / or the arrangement of the recess and / or the key plunger, a bright spot would result in the area of ​​the recess without a diffuser film according to the invention. This bright spot is masked or compensated for by the lower translucency in the second area of ​​the diffuser film, resulting in a more homogeneous backlighting of the key surface.

[0020] In further preferred embodiments, a labeling film is provided between the diffuser film and the key body. The labeling film has an opaque and / or semi-transparent inscription. This allows a key to be labelled with minimal effort. For example, a number from a numeric keypad can be displayed on the key.

[0021] In advantageous embodiments, the key body is recessed into a decorative cover with cutouts corresponding to the key shape. This advantageously separates each key, for example, from other keys on a keyboard. This ensures that it is always pressed individually. Furthermore, the decorative cover creates an attractive appearance for the home communication system. The cover is either painted and / or made of a visually appealing material, such as stainless steel.

[0022] In preferred embodiments, the key sensor assembly comprises at least one piezoelectric sensor and preferably a number of piezoelectric sensors corresponding to the number of keys. In particular, one piezoelectric sensor is provided for each key. Piezoelectric sensors enable a particularly compact design of the key sensor assembly and are especially reliable.

[0023] In advantageous embodiments, light sources, in particular side-LEDs, are provided on the sides of the light distribution plate. Side-LEDs are preferably LEDs (light-emitting diodes) characterized by the fact that they direct light onto a side surface of the light distribution plate. Preferably, two such side-LEDs are provided on each side of the light distribution plate.

[0024] In one embodiment, light-emitting structures are particularly preferred on the light distribution plate, preferably designed as laser-generated structures. These contribute to homogeneous illumination of the key. The light-emitting structures can be produced, for example, by laser ablation, i.e., by local surface removal through vaporization (sublimation) of material at the focus of a laser beam directed onto the material surface. Alternatively or additionally, by focusing the laser beam within the solid material, which is essentially transparent, light-scattering structures can also be selectively introduced within the material.

[0025] In preferred embodiments, a reflective film, preferably containing polyethylene terephthalate (PET), is provided on the back of the light distribution plate. This is advantageously provided in addition to the light-emitting structures on the back of the light distribution plate. The reflective film advantageously reflects light scattered or backscattered from the rear to the front. In doing so, the light is also advantageously scattered again. Overall, this results in even more homogeneous illumination through multiple scattering and brighter illumination of the key through reflection.

[0026] In the context of the present invention, a keyboard can also be understood to mean a single key. Preferably, the keyboard has at least two keys. However, the invention is particularly preferred if the keyboard has a keypad, i.e., a plurality of keys arranged side by side and / or one above the other. A keyboard that is particularly common in home communication systems is the so-called standard telephone keypad with a key array of 4 rows and 3 columns.

[0027] In preferred embodiments of a keyboard for home communication systems, a common diffuser film with a plurality of first and second zones is provided for all keys of the keyboard. The plurality of first and second zones corresponds in particular to the number of keys. This allows for particularly simple manufacturing and assembly of the diffuser film. In particular, if the diffuser film is printed, this speeds up the printing process because a plurality of printed zones, especially the second zones, can be applied to a single film.

[0028] In preferred embodiments, a common key sensor and / or reflective film and / or light diffusion plate and / or labeling film and / or decorative cover is provided for all keys of the keyboard. Advantageously, as few individual parts as possible are used. Instead, functionally identical parts preferably extend across the entire keyboard in a single piece. Furthermore, optionally or additionally, several key bodies can be formed together in one piece, for example, by being connected via a bridge or a common center, which in each case represents the corner of a key body. Preferably, two key bodies are formed together as a rocker switch or four key bodies are formed together in a cloverleaf-like configuration. Such embodiments also have the advantage that, due to the rocker-like design, two opposing keys can never be pressed simultaneously.This also advantageously prevents potential malfunctions that might result from the simultaneous, unintended activation of multiple buttons.

[0029] In one embodiment, a sealing plate is provided between the key bodies and the decorative cover, which prevents moisture from penetrating between the key body and the decorative cover.

[0030] The above embodiments and further developments can be combined with one another as appropriate. Further possible embodiments, further developments, and implementations of the invention also include combinations of features of the invention described previously or subsequently with regard to the exemplary embodiments, even if not explicitly mentioned. In particular, the person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the present invention. CONTENT OF THE DRAWING

[0031] The present invention will be explained in more detail below with reference to the exemplary embodiments shown in the schematic figures of the drawing. These figures show: Fig. 1 A top view of a keyboard of a home communication system; Fig. 2 a side view of the keyboard Fig. 1 with a break in the area of ​​the keys, showing a cross-section; Fig. 3 a detailed view of a button for home communication systems; Fig. 4. View the details Fig. 3 showing the areas of different translucency of a diffuser film; Fig. 5 an exploded view of a keyboard according to the invention for a home communication system.

[0032] The accompanying figures are intended to provide a further understanding of the embodiments of the invention. They illustrate embodiments and, in conjunction with the description, serve to explain the principles and concepts of the invention. Other embodiments and many of the advantages mentioned will become apparent with reference to the drawings. The elements of the drawings are not necessarily shown to scale.

[0033] In the figures of the drawing, identical, functionally equivalent and similarly acting elements, features and components - unless otherwise stated - are each provided with the same reference symbols. DESCRIPTION OF EXAMPLES OF EXECUTION

[0034] Fig. Figure 1 shows a top view of a keypad 10 of a home communication system. The keypad 10 shown has 16 keys 2 according to the invention, which are evenly arranged in a 4x4 grid. The keys are embedded in a decorative cover 1. This can be, for example, made of stainless steel or painted.

[0035] In Fig. 2 is a side view of the keyboard 10 from Fig. 1 with a breakout in the area of ​​keys 2.

[0036] Fig. 3 and Fig. Figure 4 shows a detailed view of a button for home communication systems, which is located in Fig. Figure 2 shows a detailed section. This section depicts a piezoelectric sensor 8. Piezoelectric sensors are generally known to those skilled in the art in the field of home communication systems, which is why they will not be discussed further within the scope of the present invention. Alternatively, other push-button sensors can be used instead of a piezoelectric sensor.

[0037] A reflective film is positioned in front of the piezoelectric sensor. In the context of the illustrated embodiments, the orientation "front" is always to be understood as oriented towards the free surface of the button 2. The orientation "back" is the opposite. A light distribution plate 4 is positioned in front of the reflective film 5. A recess is provided in the light distribution plate 4, in which a button plunger 3 is located. A diffuser film 7 and a labeling film 6 are positioned in front of the light distribution plate 4 and the button plunger 3. A button body 9, which is embedded in a decorative cover 1, is located in front of the labeling film 6. A sealing plate 11 is provided between the button body 9 and the decorative cover 1. In this arrangement, pressure, for example from an operator, on the button body 9 is transmitted via the labeling film 6 and the diffuser film 7 to the button plunger 3.This protrudes slightly forward from the light distribution plate 4 and thus receives the button press completely or almost entirely. Furthermore, the button plunger 3 is positioned at its rear end directly against a piezoelectric sensor, thereby transmitting the button pressure precisely to the sensor. This ensures reliable activation of the desired piezoelectric sensor, which is assigned to the respective button 2, by pressing the button body 9.

[0038] The illumination or backlighting of button 2 is achieved by means of side LEDs (not shown), with, for example, two side LEDs provided on each side of the light distribution plate 4. The light distribution plate 4 is designed such that a uniform light distribution is achieved without cutouts 13. This is facilitated by laser-generated light output structures (not shown) located on the back of the light distribution plate 4. These can be produced, for example, by laser abrasion, i.e., by local surface removal through the vaporization of material at the focus of a laser beam directed onto the material surface.

[0039] Alternatively or additionally, by focusing the laser beam within the material, which is essentially transparent, targeted light-scattering structures can also be introduced within the material. Additionally, a reflective film 5 is provided on the back of the light distribution plate 4, which reflects light scattered from the back towards the front. This scatters the light further. Overall, the multiple scattering results in homogeneous illumination of the key 2. However, this homogeneous illumination is disrupted in the area of ​​the recess 13 in the light distribution plate 3.

[0040] To prevent a dark spot from forming in the area of ​​the recess(s) 13 in which the key plunger 3 is located, the key plunger 3 is also designed to be transparent. The transparent design of the key plunger 3 and the light-diffusing plate 4 is advantageously achieved by using a transparent plastic such as polymethyl methacrylate (PMMA). At the interface between the recess(s) 13 and the key plunger 3, the light is refracted. Reflections are also generated at these interfaces. Depending on the refractive properties of the material used, this results in different illumination patterns on the visible key surface at the locations of the recess(s) 13 and the key plunger 3 compared to the otherwise homogeneously backlit surface of the key.

[0041] In the present embodiment, the recess(s) 13 create bright spots on the visible key surface, i.e., light is concentrated at the respective locations of the recess(s) 13 or key plunger 3. This effect is compensated for or masked by a diffuser film 7. For this purpose, the diffuser film 7 has a different translucency in the area T2 of the recess(s) 13 compared to the remaining area T1 of the diffuser film 7.

[0042] In the present example, the translucency in area T2 is lower than in area T1, which forms the remainder of the diffuser film 7 shown. As a result, the key appears homogeneously backlit on the front of the diffuser film 7. This effectively compensates for the negative optical effect of the recess(s) 13, while still allowing the mechanical advantages of the recess(s) 13 for the key 2 to be utilized. The lettering film and the transparent key body are thus backlit in a visually appealing and homogeneous manner.

[0043] Fig. Figure 4 shows the detailed view again. Fig. Figure 3 shows the arrangement of areas T1 and T2 with different translucencies on the diffuser film 7. The diffuser film 7 has a large area of ​​first translucency in area T1, which is relatively high in this embodiment. In area T2 of the diffuser film 7, which is located at the key plunger 3 and at the recess 13 of the light distribution plate 4, the translucency is lower. This conceals the bright spot that results from the different refraction of light at this point compared to the rest of the light distribution plate.

[0044] In the T2 area, in addition to lower translucency, a particularly advantageous feature is the increased reflectivity on the back, allowing any light that is not transmitted to illuminate the remaining area of ​​button 2 through reflection. The different translucency levels are adjusted by a specialist depending on the brightness differences to be compensated for. This is achieved, in particular, by printing the diffuser film in a way that is adapted to the brightness differences.

[0045] In Fig.Figure 5 shows an exploded view of a keyboard 10 according to the invention for a home communication system. A further embodiment of a decorative cover 1 on the front of the keyboard 10 and an alternative embodiment of an illuminated piezoelectric keypad 12, shown in this case pre-assembled, are also shown. This keypad has a fixedly mounted light distribution plate 4 and piezoelectric sensors 8 integrated behind it, which are laminated into a film. Recesses 13 (not shown) are provided in the light distribution plate 4, in which transparent key plungers 3 (also not shown) are arranged. Between the piezoelectric keypad and the decorative cover, the diffuser film 7, the labeling film 6, 16 key bodies 9, and a sealing plate 11 are shown, arranged in this order from back to front.The diffuser film 7, the lettering film 6, the sealing plate 11, and the decorative cover 1 are each formed in one piece. The key bodies 9 are each formed in groups of four, arranged in a cloverleaf pattern, as a single piece.

[0046] In this embodiment, the keyboard comprises a total of 16 keys 2, corresponding to four such cloverleaf-shaped key body elements, each with four key bodies 9. The sealing plate 11 and the decorative cover 1 each have recesses for the key bodies 9, which are inserted into these recesses during assembly. Thus, in the assembled state, the key bodies 9 are recessed in the decorative cover 1 and the sealing plate 11.

[0047] Although the present invention has been fully described above with reference to preferred embodiments, it is not limited thereto, but can be modified in many ways.

[0048] As an alternative to a piezo sensor, the key sensor system can be designed with any type of key sensor, for example in a mechanical flat design (metal snap disc on a circuit board), a silicone keypad arrangement (conductive contact pill and silicone mat / cap) or other switch sensor systems.

[0049] In alternative applications, the diffuser film can also be used to deliberately create light effects in the keys. Reference symbol list 1 decorative panel 2nd button 3 key plungers 4 light distribution plates 5 reflective foil 6 Labeling film 7 Diffuser film 8 key sensors 9 key bodies 10 keyboard 11 Sealing plate 12 Piezo keypad 13 Exclusion

Claims

[1] Backlit keyboard (2, 10) of a home communication system, with a piezo-sensitive key sensor (8), with at least one at least partially transparent key body (9), with a light distribution plate (4) which is arranged between the key sensor (8) and the key bodies (9), with a diffuser film which is arranged in front of the light distribution plate (4) and behind the key bodies (9), wherein the diffuser film (7) has a first area (T1) of first translucency and a second area (T2) of second translucency. [2] Keyboard according to claim 1, characterized by, that the light distribution plate (4) has recesses in which key plungers (3) are provided, wherein each key plunger (3) is arranged and designed in such a way that it is in operative contact with the key body (9) and the key sensor (8) and that it transmits a mechanical actuation of the key body (9) to a predetermined area of ​​the key sensor (8). [3] Keyboard according to any of the preceding claims, characterized by , that a transition between the first and second areas (T1; T2) of the diffuser film (7) is formed with a continuously changing translucency. [4] Keyboard according to claim 3, characterized by , that the diffuser film (7) is designed as a printed film and the different translucency in the first and second areas (T1; T2) is realized by different printing of the diffuser film (7). [5] Keyboard according to any of the preceding claims, characterized by, that the key plunger (3) is at least partially transparent, in particular completely transparent. [6] Keyboard according to one of the preceding claims, characterized by , that the key plunger and / or the light distribution plate (4) is made of a plastic, in particular of polymethyl methacrylate (PMMA). [7] Keyboard according to one of the preceding claims, characterized by , that the second area (T2) has a lower translucency than the first area (T1) and is located in the area of ​​the recess and / or the key plunger. [8] Keyboard according to any of the preceding claims, characterized by , that a labeling film (6) with an opaque or semi-transparent label is provided between diffuser film (7) and key body (9). [9] Keyboard according to any of the preceding claims, characterized by, that a decorative cover (1) is provided and that the key body (9) is formed to be recessed into a decorative cover (1). [10] Keyboard according to any of the preceding claims, characterized by , that the key sensor system (8) comprises at least one piezo sensor and preferably a number of piezo sensors corresponding to the number of keys. [11] Keyboard according to any of the preceding claims, characterized by , that light sources, in particular side-LEDs, are provided on the side of the light distribution plate (4). [12] Keyboard according to any of the preceding claims, characterized by , that light output structures are provided on the light distribution plate (4), which are designed in particular as laser-generated structures. [13] Keyboard according to any of the preceding claims, characterized by , that a reflective film (5) is provided on the back of the light distribution plate (4). [14] Keyboard according to any of the preceding claims, characterized by , that a keypad with at least two keys (2), in particular a keypad designed as a standardized telephone keypad, is provided. [15] Keyboard according to claim 14, characterized by , that a common diffuser film (7) with a plurality of first and second areas (T1; T2) is provided for all keys (2) of the keyboard (10), wherein the plurality of first and second areas (T1; T2) corresponds in particular to the number of keys (2). [16] Keyboard according to one of claims 14 or 15, characterized by , that a common key sensor (8) and / or reflective film (5) and / or light distribution plate (4) and / or labeling film (6) and / or decorative cover (1) is provided for all keys (2) of the keyboard (10).

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