DE102012111824B4 - Illuminated flat input keypad - Google Patents

Abstract

Flat input keyboard, comprising a front panel (10) forming a plurality of keypads (12), a light-guiding film (14), a spacer layer (16) and at least one light source (24) for coupling light into the light-guiding film (14), wherein the spacer layer (14) 16) under each keypad (12) has a recess in which a contact device (20) is arranged,
wherein the light-guiding film (14) comprises a plurality of tongues (26), wherein a tongue (26) arranged in the region of a respective keypad (12) in a frame (30) surrounding the tongue (26) passes through at least one slot (28) in the light-guiding foil (14), the slot (28) surrounding the tongue (26) on three sides, the tongue (26) being movable relative to the frame (30),
wherein below the respective tongue (26) in each case by pressing the tongue (26) operable contact means (20) in the recess of the spacer layer (16) is arranged, and
wherein the respective tongue (26) has at least one Lichtauskoppelstruktur (34) for coupling out by the light source (24) in the Lichtleitfolie (14) coupled light.

Description

The invention relates to a flat-input keyboard with a front panel forming at least one keypad.

Such flat-input keyboards are known for example in the form of membrane keyboards, in which the front sheet is depressed in the region of a keypad for the operation of a key to make an electrical contact. In this case, an electrical contact between interconnects on a carrier substrate is produced via a snap disk in the form of a curved metal plate. At the same time, the snap disc gives tactile feedback when the button is pressed.

There are also known flat input keyboards in which individual buttons are arranged behind a front foil, which are actuated by depressing the front foil in the region of the tactile surfaces.

DE 20 2007 006 647 U1 describes an illuminable membrane keyboard with a light-emitting diode formed from an organic light-emitting diode (OLED), which is arranged between a snap disc of a switching layer and a transparent region having an outer layer. An OLED element is applied to a flexible film which moves when a button is operated.

DE 20 2004 007 474 U1 describes a lighted, foil-covered, click-based keyboard. A front foil has elevations, which are arranged via snap discs. An insert segmented into segments with opaque partition is integrated on the underside of an elevation. The segments have different colors and are laterally irradiated by LEDs.

DE 20 2007 016 762 U1 describes a membrane keypad with luminous keys, in which an illuminable surface is formed from a cutout in a spacer film, in which a key body and a side surrounding the key body scattering body is arranged. The key body is arranged over a snap disk as areal radiator. The key body is laterally enclosed by the diffuser, is irradiated in the light of a LED. The key body is roughened on one or both sides for uniform light distribution. A printing of a front foil is transparent in the area of the key body and opaque outside.

DE 20 2011 105 529 U1 describes a light guide structure having a keypad structure in which the light guide structure is formed with a protruding light condensing structure having a vertical surface and a curved slope surface. The vertical surface serves as a receiving surface to receive light from an LED. Light reaching the curved slope surface may be reflected in the light guide layer. A microstructure region for reflecting or diffracting the light propagated from the photoconductive layer and a bulb disposed over a conductive dome are cast together with the photoconductive layer and the light condensing structure.

US 2009/0129049 A1 describes a slot-segmented optical fiber for illuminating a keyboard. The slots can be generated for example by laser cutting. A segment comprises several buttons. Different segments are illuminated by arranged in sections, different light emitting diodes.

US 2009/0173610 A1 describes a keyboard with a light guiding layer in which rectilinear slits delimit a region illuminated by a light emitting diode.

US 2009/0194401 A1 describes a keyboard in which a pattern of a light guide film with increasing distance from light sources has an increasing density to cause a uniform light-emitting surface.

US 2008/0257699 A1 describes a keyboard with a light guide plate which extends as a continuous plate over all contacts.

DE 10 2008 061 499 A1 describes a foil-shaped optical fiber component in which a slot is provided for subdivision into light exit zones. In each light exit zone, a plurality of switching elements are provided.

The object of the invention is to provide a novel illuminated keyboard that is as flat as possible and yet easy to use.

This object is achieved by a flat-input keypad, with a front panel forming several keypads, a light-guiding foil and at least one light source for coupling light into the light-guiding foil, wherein the spacer layer under each keypad has a recess in which a contact device is arranged Lichtleitfoli comprises a plurality of tongues, wherein a tongue arranged in the region of a respective tongue in a frame surrounding the tongue is defined by at least one slot in the Lichtleitfolie, the slot surrounding the tongue on three sides, wherein the tongue is movable relative to the frame, wherein below the respective tongue in each case an actuatable by depressing the tongue contact device is arranged in a recess of the spacer layer, and wherein the respective Tongue has at least one Lichtauskoppelstruktur for coupling out of the light source in the Lichtleitfolie coupled tem light.

By virtue of the slot defining a tongue surrounding at least three sides of the frame, good mobility of the respective tongue is achieved upon depression of the front foil in the region of a keypad arranged above the tongue. At the same time, the slot effectively limits light scattering into the tongue from a region of the light-guiding foil that is locally separated by the slit and scattering light in the opposite direction from the tongue into the frame of the light guiding foil which is locally separated by the slit. Through this limitation of the light pipe, an individual lighting of the keypads can be made possible with a light guide foil comprising several keypads. For example, the tongues may be assigned different light sources.

Preferably, the Lichtleitfolie has at least one recess and / or at least one opening, which comprise the at least one slot and optionally the at least one Lichtauskoppelstruktur and outside of which the Lichtleitfolie is uniformly flat. For example, depressions and / or openings can be produced by processing a uniformly flat light-guiding film. The at least one slot can then be produced, for example, by laser cutting, and the at least one light extraction structure can be produced for example by laser engraving. This allows a high-precision production of a plate-shaped base material. There may thus be additional, additional depressions or openings, but no elevations. The light extraction structure may be formed at least in part by depressions and / or openings. It can also be produced at least in part by laser engraving in the form of an interior engraving in which light-scattering structures are produced in the interior of the light-guiding film.

For example, the light-guiding film may have at least one slot which defines a tongue and a frame surrounding the tongue, and at least one Lichteinkoppelstruktur for laterally coupling light into the Lichtleitfolie towards a tongue, and the tongue may have at least one Lichtauskoppelstruktur for coupling over the Lichteinkoppelstruktur have coupled light in a direction transverse to the surface of the light guide.

• - Bereitstellen einer lichtleitenden Folie;
• - Herstellen wenigstens einer Lichtauskoppelstruktur der Lichtleitfolie durch Lasergravieren und /oder Laserschneiden von Lichtstreustrukturen in die Lichtleitfolie;
• - Laserschneiden wenigstens eines Schlitzes, der eine die Lichtauskoppelstruktur umfassende Zunge und einen die Zunge umgebenden Rahmen definiert.

A method for producing the light-guiding film may include, for example, the steps:

• - Providing a photoconductive film;
• - Producing at least one Lichtauskoppelstruktur the Lichtleitfolie by laser engraving and / or laser cutting of light scattering structures in the Lichtleitfolie;
• Laser cutting at least one slit defining a tongue comprising the light extraction structure and a frame surrounding the tongue.

Advantageous embodiments of the invention will become apparent from the dependent claims.

Preferred embodiments are explained below with reference to the drawing.

• 1 eine schematische Querschnittsansicht einer Flacheingabe-Tastatur mit einer Zunge einer Lichtleitfolie unter einen Tastenfeld;
• 2 eine Draufsicht auf eine Lichtleitfolie mit Zungen;
• 3 eine vergrößerte Teilansicht eines weiteren Beispiels einer Zunge einer Lichtleitfolie mit umgebendem Rahmen; und
• 4 eine vergrößerte Teilansicht einer Variante der Flacheingabe-Tastatur aus 1.

Show it:

• 1 a schematic cross-sectional view of a flat-input keyboard with a tongue of a light guide under a keypad;
• 2 a plan view of a Lichtleitfolie with tongues;
• 3 an enlarged partial view of another example of a tongue of a light-guiding film with surrounding frame; and
• 4 an enlarged partial view of a variant of the flat input keyboard 1 ,

1 shows a partial view of a flat input keyboard in the form of a membrane keyboard with a front foil 10 that have multiple keypads 12 forms the keyboard operation, and with a light guide foil arranged behind it 14 , Below the light-guiding foil 14 is a distance layer 16 , also referred to as spacer, arranged. The membrane keyboard further comprises a substrate 18 with tracks and contact areas for keyboard operation. At the substrate 18 it may be, for example, a printed circuit board or a film substrate.

The distance layer 16 points under each keypad 12 the front foil 10 a recess in which a metallic snap-action disc 20 in an intermediate space of the light-guiding film 14 and the substrate 18 on the substrate 18 is arranged. In known manner is the upward convex domed snap disc 20 adapted to depress contact between traces on the substrate 18 produce and when releasing back to the original position.

Im in 1 example shown is an optional retaining film 22 provided the snap disc 20 in the respective recesses of the spacer layer 16 holds. The holding foil 22 limits the space for the snap disk 20 topside. The wrap 22 runs outside of the recesses for the snap disk 20 for example, between the spacer layer 16 and the light-guiding film 14 ,

1 further shows that the light guide 14 next to the keypad 12 a recess in which a light source in the form of an LED 24 is arranged. For example, the LED 24 on the substrate 18 arranged and connected to tracks for power. For example, the LED 24 in one the distance layer 16 and the light-guiding film 14 arranged penetrating recess. The LED 24 For example, is a sideways radiating LED, which is adapted to light sideways in an end face of the light guide 14 in the recess of the light-guiding film 14 towards the keypad 12 couple.

The structure of the light-guiding film 14 will be explained below by means of 1 . 2 and 3 explained in more detail, wherein 2 and 3 show different embodiments.

The light-guiding foil 14 includes in a respective keypad 12 assigned area a tongue 26 on three sides through a slot 28 from a surrounding frame 30 the light guide film 14 is disconnected. The frame 30 surrounds the tongue 26 at least 270 ° of its circumference. The tongue 26 is opposite the frame 30 movable. The tongue 26 comprises a square in the example shown Lichtabstrahlbereich 32 , which approximates the extent of the overlying keypad 12 the front foil 10 equivalent. In the light emission area 32 is the tongue 26 with top and / or bottom recesses 34 provided with a Lichtauskoppelstruktur for coupling in the Lichtleitfolie 14 form guided light. In the example shown is in 1 a top recess 34 represented by a dashed line. The light extraction structure is produced for example by laser engraving. The light-guiding foil 14 is for example made of transparent polymethyl methacrylate (PMMA). For example, it can be made with a high precision carbon dioxide laser. Through the depressions 34 results in a light from the Lichtleitfolie 14 decoupling surface. The slot 28 can be produced for example by laser cutting, for example also with a carbon dioxide laser.

In the example shown, the section for the recording of the LED is located 24 in the area of the base of the tongue 26 , ie in the connecting area of the tongue 26 with the surrounding frame 30 , The arranged in the cutout LED 24 essentially radiates into the tongue 26 one, so every keypad 12 from an associated LED 24 can be individually illuminated. As in 2 In the case of multiple keypads arranged in rows and / or columns, the light guiding foil can be shown 12 a common framework 30 for several tongues 26 form, with adjacent tongues 26 each through a section of the frame 30 are separated from each other. The LED 24 facing end face of the light guide 14 in the recess forms a Lichteinkoppelstruktur 35 for lateral coupling of light of the LED 24 in the light guide foil 14 in the direction of the tongue 26 , The Lichteinkoppelstruktur 35 can be made by laser cutting.

As in 2 and 3 is indicated, the Lichtauskoppelstruktur a with increasing distance from the Lichteinkoppelstruktur 35 have increasing light extraction efficiency. In the example shown, this is due to an increasing density of the depressions 34 with increasing distance from the front side of the recess for the LED 24 reached. Thus, the uniformity of the illumination of the surface of the Lichtabstrahlbereichs 32 be improved because in the more distant areas of the tongue 20 less light is available and this can be at least partially offset by the higher light extraction efficiency.

The wells 34 represent light scattering structures caused by a scattering of the over the Lichtleitfolie 14 light directed towards them in directions transverse to the light guide foil 14 cause the light from a surface of the light guide 14 is decoupled. Light can be both to the top of the Lichtleitfolie 14 are scattered, especially in the case of upper-side light scattering structures directly from the Lichtleitfolie 14 be coupled out, as well as to the bottom of the light guide 14 be scattered. Downscattered and / or decoupled light, for example, by the holding film 22 scattered or reflected back. From the holding foil 22 Backscattered or reflected light can be, for example, the light guide 14 penetrate and on the top side of the light guide 14 escape. The holding foil 22 forms, for example, a reflector and / or a surface spreader. The holding foil 22 includes, for example, a light-reflecting and / or reflective layer. The holding foil 22 has, for example, a white surface. You can, for example, be printed white. However, a light-reflecting and / or reflecting layer can also be directly on the underside of the light-guiding film 14 be arranged. Thus, for example, all over under the light guide 14 an optional reflector foil 36 be arranged as in 4 is shown. The holding foil 22 is when you depress a tongue 26 moved. The holding foil 22 has, for example, a certain elasticity.

3 shows an embodiment of a Lichtleitfolie 14 similar to the one in 2 represented Lichtleitfolie in a partial view, wherein a tongue 26 assigned LED 24 also shown is. 3 shows schematically a course of a slot 28 with two parallel, longitudinally of a tongue 26 extending sections at the free end of the tongue 26 are connected by a transverse section. The individual sections of the slot 28 are by a rounded course of the slot 28 connected. Through rounded corners of the slot and the tongue 28 and rounded ends of the slot 28 is the light-guiding foil 14 particularly well protected against tearing.

3 further shows an example of an optional recess 38 as part of 30 the light guide film 14 , The recess 38 For example, another LED 39 record, in particular an upwardly emitting LED. In the field of LED 39 is the front foil 10 preferably translucent. Thus, the LED allows 24 a lighting of the keypad 12 while the extra LED 39 allows the output of a status signal.

4 schematically shows the layer structure of the membrane keyboard based on another example, in which the holding film 22 also between the light guide foil 14 and the distance layer 16 is arranged. On the substrate 18 are the distance layer 16 and, in a recess of the spacer layer 16 , the snap-disk 20 arranged. The snap-disk 20 is through the holding film arranged above 22 held.

The front foil 10 includes, for example, translucent protective layer 10A and a colorant-containing decorative layer 10B and optionally a translucent support layer 10C , The decorative layer 10B forms, for example, a key symbol of the respective keypad 12 , The decorative layer 10B is, for example, translucent in some areas. The decor of the layer 10B can through the Lichtabstrahlbereich arranged behind it 32 the tongue 26 be illuminated.

Over the distance layer 16 and the holding foil 22 is the light-guiding foil 14 arranged, for example, outside of the area of the tongue 26 over an adhesive layer 40 with the retaining foil 22 or the distance layer 16 can be connected. The adhesive layer 40 represents, for example, a spacer layer. In the example shown, the adhesive layer is 40 or spacer layer only in the area of the frame 30 provided, but not at the bottom of the tongue 26 , The layer 40 However, it can also be on the bottom of the tongue 26 be provided. For example, the Lichtleitfolie 14 with the adhesive layer 40 be provided, and the slot 28 can in the light guide 14 and the layer 40 get cut.

In the example shown, the light guide is 14 also on the top side over another adhesive layer 42 or spacer layer with the front foil 10 or an optional, underside of the front foil 10 arranged Lichtdiffusorschicht 44 connected. The layer 42 For example, it is only in the area of the frame 30 intended. If the adhesive layer 42 not on the top of the tongue 26 This can increase the flexibility of the tongue 26 improve.

The optional light diffuser layer 44 is designed to diffuse diffuse light. This allows the uniformity of the illumination of a keypad 12 be improved. The light diffuser layer 44 is in particular a translucent, translucent Lichtdiffusorschicht. In the light diffuser layer 44 For example, it can be a white glaze print on the front foil 10 act. The diffuser layer 44 For example, you can access the areas of the respective keypads 12 be limited, or applied over the entire surface.

As in 4 is shown schematically, the Lichtleitfolie 14 optionally a bottom reflector foil or reflector layer 36 have, for example, a light diffusely reflecting, white reflector foil.

Optionally, a reflector foil 46 on the top side of the light guide foil 14 be provided in non-illuminated areas.

In addition to those described above, further layers may be provided in the construction of the membrane keypad, for example adhesive layers for joining superimposed films or layers.

The structure of the membrane keypad described by means of examples allows a particularly flat design. For example, the membrane keyboard above the surface of the substrate 18 a height in the range up to 1.5 mm to the front of the front foil 10 preferably have a height in the range up to 1.0 mm.

The LEDs 24 can have different colors. For example, there may be several LEDs 24 for scattering light into a tongue 26 be provided. For example, multiple LEDs 24 be provided side by side in a recess, or a plurality of recesses, each with at least one LED 24 , Other light coupling structures for LEDs 24 For example, they may be made by laser engraving and / or laser cutting. Also an outer edge of the light guide 14 can serve as Lichteinkoppelstruktur, for example, if an LED 24 placed in front of the edge so that the light is directed towards a tongue 26 is directed.

In the examples shown, the LEDs emit light 24 sideward light, ie parallel to the component side. There are also conceivable variants in which the LEDs 24 on the upper side, ie opposite the component side, emit light. A reflector layer may be provided above the LED and, optionally, spaced therefrom, to relay, ie to reflect, light below the reflector layer in the direction of the light guide film. The reflector layer can, for example, on the underside of the front sheet 10 be arranged and can be over the LED 24 and additionally over a portion of the light guide 14 extend. The LED 24 can in the recess of the light guide 14 protrude. But it can also end below. An end face of the recess can nevertheless be a Lichteinkoppelstruktur 35 for the LED 24 form.

The use of LEDs to illuminate the membrane keyboard results in addition to a flat design, the other advantages of a long life and reliability of lighting and a simple controllability and low power consumption.

In the examples described, one is by depressing the respective tongue 26 operable snap disc arranged as contact means below the tongue. However, the flat input keyboard may also have other contact devices. For example, a contact element in the form of a contact plate may be provided below the tongue 26 is arranged and set up by depressing the tongue 26 an electrical contact between contact areas on the substrate 18 or between the contact pad and a contact area. The contact regions may be formed meander-shaped, for example, in a manner known per se.

Claims (7)

A flat-input keyboard comprising a front panel (10) forming a plurality of keypads (12), a light-guiding film (14), a spacer layer (16) and at least one light source (24) for coupling light into the light-guiding film (14), wherein the spacer layer (14) 16) under each keypad (12) has a recess in which a contact device (20) is arranged, wherein the Lichtleitfolie (14) comprises a plurality of tongues (26), wherein a tongue (26) arranged in the region of a respective keypad (12) in a surrounding the tongue (26) frame (30) through at least one slot (28) in the Lichtleitfolie (14), the slot (28) surrounding the tongue (26) on three sides, the tongue (26) being movable relative to the frame (30), wherein below the respective tongue (26) in each case by pressing the tongue (26) operable contact means (20) in the recess of the spacer layer (16) is arranged, and wherein the respective tongue (26) has at least one Lichtauskoppelstruktur (34) for coupling out by the light source (24) in the Lichtleitfolie (14) coupled light. Flat input keyboard after Claim 1 in which the light-guiding film (14) has at least one recess for receiving the light source (24). Flat input keyboard according to one of the preceding claims, wherein the light-guiding film (14) has at least one Lichteinkoppelstruktur (35) for side coupling of light of the at least one light source (24). Flat input keyboard after Claim 3 in which a density of light scattering structures of the at least one light extraction structure (34) of a tongue (26) increases with increasing distance from the light coupling-in structure (35). A flat input keyboard according to any one of the preceding claims, wherein a plurality of keypads (12) each having at least one slot (28) associated with the light guide (14) defining a tongue (26) located in the region of the respective keypad (12), and wherein a plurality of keypads (12) are associated with different light sources (24) for illuminating a respective keypad (12). A flat input keyboard as claimed in any preceding claim, wherein the at least one light source (24) comprises at least one light emitting diode (24). A flat input keyboard as claimed in any one of the preceding claims, wherein the at least one light extraction structure (34) comprises diffractive light patterns in the form of recesses.

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