WO2012172167A1 - User input arrangement and related method of manufacture - Google Patents

Abstract

A free space light propagation-based user input arrangement (202, 502), such as a user input arrangement of a touchscreen or a touch-pad, comprises a number of light emitters (204, 204a, 302b) and corresponding detectors (204, 204b, 302b) configured to transmit light and detect the transmitted light, respectively, the light to be transmitted and detected optionally being or at least including infrared or ultraviolet region light, at least one transmissive element (208, 308) comprising optically substantially transmissive material such as optically substantially transparent material, wherein said at least one transmissive element is to be arranged substantially along or around the edge such as the perimeter of a touch area (212c) on which a touch is to be detected, and wherein the emitters and detectors of said number have been at least partially embedded in the transmissive material of the at least one transmissive element such that, when in use, the light couples from each emitter to the transmissive material of the at least one transmissive element, enters the free space therefrom, propagates in the free space on the touch area and reaches, upon no touch action (212) in the free space interrupting the light propagation, the transmissive material and couples therefrom to the corresponding detector. A corresponding method of manufacture is presented.

Description

USER INPUT ARRANGEMENT AND RELATED METHOD OF MANUFACTURE

FIELD OF THE INVENTION

Generally the present invention relates to optics and electronics. Particularly, however not exclusively, the invention pertains to UIs (user interface) comprising a touch input arrangement such as a touchscreen arrangement. BACKGROUND

Touchscreens may apply of a number of varying technologies for obtaining the touch-sensitive functionality. Among various other potential options e.g. capacitive, resistive, infrared or generally 'free space', optical imaging (camera-based), acous- tic, and hybrid solutions are feasible.

With reference to scenario 102 of Figure la, many contemporary free space, or 'free air', touch displays implement an unrestricted optical connection 104 between a number of light emitters 108 and light detectors 1 10 over a display surface 106.

In some slightly different free space solutions, the emitters 108 and detectors 1 10 have been actually placed below the display level, e.g. directly onto a PCB (printed circuit board) together with other electronics residing within the display device, whereupon various additional elements such as waveguides and/or reflective ele- ments, typically mirror elements, have been applied to couple the light from the emitters to propagate over the display and be redirected back therefrom to the detectors on the PCB.

Generally in conjunction with the aforementioned solutions and with particular ref- erence to scenario 109 of Figure la, a finger or a stylus may directly interrupt the free space light beam(s) 104 and prevent or at least reduce light reception at the corresponding detector(s) 1 10. In the illustrated case, a fingertip 1 12 is placed on the top surface of the display structure 106 so that at least part of the emitted light 104 is absorbed (in the finger), diffusively reflected, and/or refracted 1 14 at the particu- lar location of contact in different directions, and possibly only a portion of the original ray, having thus reduced energy, ultimately reaches the far-end detector 1 10 as in the upper sketch 102. The amount and distribution of light reaching the detectors 1 10 is thus dependent on the disturbance introduced to the light path by e.g. a fingertip or a stylus applied for control input purposes.

Figure lb discloses a free space touchscreen arrangement with multiple emitters 120, 122 and multiple detectors 1 18, 124 disposed on the edges of a display 106. The broken lines 1 16 denote the beams that cover a predetermined touch area on the display 106 and conceptually form a two-dimensional light beam grid or 'matrix' that enables determining the touch location on the basis of detecting the locations of interrupted beams in said two dimensions. The emitters 120, 122 and detectors 1 18, 124 may be covered by a display border structure not shown in the figure for clarity reasons.

Without any intention to deny the advantages and benefits offered by currently available touchscreen or corresponding solutions in providing more sophisticated UI means over more conventional options such as keyboards and mouses, certain problems still exist therewith naturally depending on each particular use case. For example, rather commonly the traditional touchscreens are often somewhat pricey to implement and manufacture. Relatively complex light funneling optics or emitter/detector placement arrangements, which are potentially also space consuming and add to the thickness of the UI, may be necessary. Further, the required extra components induce additional weight and cause optical coupling losses, i.e. efficiency losses, as the number of components such as waveguides, prisms, lenses, mirrors, and/or gratings on the optical transmission path between the emitters and detectors increases. Such components also require some more design work. The re- suiting touchscreens may actually consume a surprising amount of power in the context of power consumption -sensitive mobile devices.

SUMMARY OF THE INVENTION The objective of the embodiments of the present invention is to at least alleviate one or more of the aforesaid drawbacks evident in the prior art arrangements in the context of UI arrangements utilizing a free space touch input device such as a touchscreen. The objective is generally achieved with an arrangement for obtaining user input, wherein a number of emitters and/or detectors may be at least partially embedded, preferably by molding or lamination, within an optically transmissive element such as a waveguide element. Indeed, in accordance with one aspect of the present invention a free space light propagation -based user input device, such as a touchscreen or a touchpad, comprises a number of light emitters and corresponding detectors for transmitting light and detecting the transmitted light, respectively, the light optionally being infrared or ultraviolet region light, at least one transmissive element, optionally exactly one transmissive element such as a frame, said at least one transmissive element comprising optically substantially transmissive material such as optically substantially transparent material, wherein said at least one transmissive element is to be arranged substantially along or around the edge such as the perimeter of a touch area on which a touch is to be detected, wherein the emitters and detectors of said number have been at least partially embedded in the transmissive material of the at least one transmissive element such that, when in use, the light couples from each emitter to the transmissive material of the at least one transmissive element, enters the free space therefrom, propagates in the free space on the touch area and reaches, upon no touch action in the free space interrupting the light propagation, the transmissive material and couples therefrom to the corresponding detector.

Preferably at least the light emitting or receiving, i.e. light-sensitive, portion of the optoelectronic component such as an emitter or a photodetector is embedded within the transmissive material so that the optical and physical coupling of light between these two (component vs. transmissive material of transmissive element) may be properly achieved without additional coupling elements or structures. The transmissive element hosting at least part of an emitter acts as a carrier for the light and funnels it from the emitter to the free space over the touch area, where the light propa- gates along a detection plane towards e.g. a dedicated receiving side transmissive element or the receiving portion of the very same transmissive element that also hosts the emitter, whereupon the light, if not disturbed by a touch action and related finger, stylus, or other actuation element, enters the transmissive material and reaches the light-sensitive portion of the detector.

In one embodiment, at least one of such transmissive elements is molded. The transmissive element may be over-molded onto at least one aforesaid optoelectronic component such as emitter(s) and or detector(s). Injection molding may be applied, for instance. A number of optoelectronic components and optionally support electronics such as conductors and/or connectors, may be thus at least partially embedded in the transmissive element. The support electronics may be generally configured to provide power, control and/or communications connection to further elec- tronic components such as the optoelectronic components.

In another, either supplementary or alternative embodiment, at least one of such transmissive elements is laminated onto at least one aforesaid optoelectronic component and optionally onto support electronics.

In a further, either supplementary or alternative embodiment, a substrate element has been initially provided with at least one optoelectronic component such as the aforesaid emitter(s) and or detector(s), optionally also support electronics. For example, techniques of printed electronics such as inkjet printing may have been ap- plied for the purpose regarding at least one or more of the components. A number of emitters and/or detectors may be thus provided utilizing printed electronics technology. The transmissive element has been then provided such as molded or laminated onto the at least one optoelectronic component and optionally on the support electronics. The applied substrate may include a film of plastic, such as a flex film, or of other desired material.

In some embodiments, the transmissive element(s) and the related, at least partially embedded emitters and detectors may be located such that the light may enter and exit the detection plane on the touch area directly substantially without reflections within the sending or receiving side transmissive material and optionally during the free space leg. Thus, a zero-order path with no reflections may be configured. Accordingly, the emission axis of the emitter or the reception axis of the receiver may be directly matched with the detection plane. In some embodiments, the transmissive element may form or at least include a waveguide, i.e. a lightguide, which may be optionally configured to enable TIR- based (total internal reflection) light propagation between a predetermined incou- pling or outcoupling surface thereof and the embedded optoelectronic component such as detector or emitter, respectively. The transmissive element may be at least partially bendable. It may include at least one curved portion. It may include a number of layers or portions with different refractive indexes, wherein the portion for guiding and transmitting light may have a higher refractive index than the surrounding layers or portions to the total internal reflection to occur. Thus, the em- bedded optoelectronic components may be located remote or at least their emission direction/axis or detection direction/axis thereof be aligned different from the actual detection plane. In some embodiments, external medium, such as gaseous medium like air of the free space, may be utilized as at least one layer of lower refractive in- dex relative to the light-conveying material of the transmissive element. Also in that case, the transmissive element acting as a lightguide still includes at least one optically feasible material layer, i.e. the layer in which the light is supposed to propagate. The properties of the lightguide including the refractive index of the lightguide material(s) are preferably selected and the emitters and detectors configured so as to enable, when in use, total internal reflection (TI ) -type propagation of light.

In some embodiments, the material of the at least one transmissive element is selected durable enough to act as a protective cover for the embedded electronics. In some embodiments, the at least one transmissive element is configured to form at least part of a bezel structure surrounding the touch area. The at least one transmissive element and optionally the related bezel may border the touch area immediately with no intermediate other areas or elements in between, or be remote, with some distance therefrom as to be described in more detail hereinafter.

In the various embodiments of the present invention, recognition of a touch may be based on low signal or signal level, such as level indicative of light intensity, drop as detected by at least one detector according to predetermined, optionally adaptive, criterion or criteria when the associated emitter(s) is active and the emitted signal should reach, in the absence of touch, the at least one detector with a predetermined, strong signal level.

In one embodiment, a touchpad structure comprises or is at least associated with the arrangement of the present invention. Optionally the touchpad comprises an ele- ment, such as a number of LEDs, OLEDs or other light sources, located so as to be capable of emitting visible light substantially towards the user of the touchpad. For instance, the element may be located, in view of the touchpad user, under the touch- sensitive surface area of the touchpad. By controlling the light emission by the element (e.g. independent light sources such as LEDs thereof) and/or optional one or more intermediate elements of the optical path, such as a (black) foil with a desired design (e.g. shapes, patterns etc., which may be attained by perforation, for example), a number of icons or other symbols (graphics, letters, etc.) may be formed and displayed to the user. The icons or other symbols may thus be dynamic, e.g. activat- ed/deactivated and/or changed dynamically by activation/deactivation of the associated light source(s) and optionally the intermediate elements. By pressing a corresponding location on the touch-sensitive area, the action associated with the displayed icon or other symbol, such as activation of e-mail software, may be triggered in the host device accommodating or being at least functionally connected to the touchpad and the arrangement.

In other embodiment, a system comprising a display and the arrangement is provided to implement a touchscreen. The display for providing a touch (surface) area and the arrangement for providing the touch feature thereto may be optionally integrated according to desired degree. For instance, a number of common parts and/or housing may be utilized.

Alternatively, an embodiment of the arrangement in accordance with the present in- vention may be originally manufactured separately and be then factory- or retrofitted to an existing display, for example.

In the above or some other embodiments, at least portion of the support electronics, such as conductors, may include printed electronics constructed on a substrate. Al- ternatively or additionally, non-printed electronics may be applied.

Likewise, in the above or some other embodiments at least portion of the remaining electronics, such as the emitters, detectors, and/or other elements, may be printed on a substrate by utilizing a selected printing technique, or attached as ready-made en- tities, e.g. SMT (surface-mount technology) and/or flip chip entities, to the substrate by e.g. glue or other adhesive. The optoelectronic components such as SMT components utilized may contain an integrated package. The package may include optically transmissive material. For example, a LED package may comprise optically transmissive resin material or other optically transmissive material as encapsulant. Alternatively, an optoelectronic component to be utilized in an embodiment of the present arrangement may omit own package and/or optically transmissive encapsulant material. E.g. a bare die, or 'chip', may be applied or an OLED structure be printed on the substrate and then be covered by a transmissive element. The die may be emissive or photosensitive.

In various embodiments of the present invention the touch action may refer to placing an actuation element such as a finger or a stylus substantially into physical contact with or at least vicinity of the predetermined touch area of the touch input de- vice, such as a touchscreen or touch pad, such that at least one light ray of the detection plane spanned by the aforesaid number of emitters and detectors is interrupted and the related signal level change, typically loss, is experienced at the corresponding detector.

The touch is typically initiated for control input purposes, such as triggering an action, at a target device that is at least functionally coupled to the touchscreen arrangement. The detection levels for recognizing a sufficient drop in the signal transmission performance between at least one predetermined emitter and at least one predetermined detector when the at least one predetermined emitter is active, which indicates a deliberate touch, may be determined by testing the response and/or change thereof at the detector a) when the emitter is constantly on and b) when a predetermined ac- tuation element or range of elements, such as a fingertip (skin), is placed on the touch area thus interrupting the emitted beam(s). The detection threshold may be fixed or adaptive. In one embodiment, adaptive threshold analyzer logic may be configured to determine the change in the detected intensity of light relative to an adaptive basic intensity level, instead of absolute values, for recognizing a touch. The basic level may be measured with a longer time window either constantly or in a timed manner, e.g. at intervals. For example, ambient light reaching the detectors may affect the basic level setting.

In various embodiments, the emitters may be or include optoelectronic components such as LEDs (light emitting diode) or OLEDs (organic LED), for example. As mentioned hereinbefore, one or more of the components may have been manufactured by the techniques of printed electronics.

In various embodiments, the photosensitive detectors may be or include optoelec- tronic components such as photodiodes or phototransistors, for example. In addition or alternatively, image sensors such as CCD (charge coupled device), MOS (metal- oxide semiconductor), or other types of sensors may be applied. Again, techniques of printed electronics may be applied for production. In various embodiments, the transmissive material of the transmissive element may include glass or plastics, for example. It may include e.g. PC (polycarbonate), PMMA (polymethyl methacrylate). PA (polyamide, nylon), COC (cyclo olefin copolymer), and/or COP (cyclo olefin polymer). The piece may optionally contain a number of recesses, cavities, or holes for accommodating at least part of elements such as emitters, detectors and/or support electronics disposed on the substrate.

In various embodiments, a substrate for the electronics and/or the transmissive ele- ment may include corresponding material, e.g. PET (polyethylene terephthalate), PC, PEN (polyethylene naphthalate), PI (polyimide), LCP (liquid crystal polymer), PE (polyethylene), and/or PP (polypropylene). Alternatively, different material may be utilized. In various embodiments, the number of emitters and detectors may be, but does not have to be, equal. In one embodiment the emitters and detectors are organized in pairs, whereupon one pair may, in one activation option, be arranged to be active at a time. In a minimum case, there is a single emitter and detector in the arrangement. In another aspect of the present invention, a method for manufacturing an arrangement for a user input device, such as a touchscreen or a touchpad, comprises:

-obtaining a number of light emitters and corresponding detectors for transmitting light and detecting the transmitted light, respectively, the light optionally being in- frared or ultraviolet region light, and

-embedding, optionally by molding or lamination, said emitters and detectors in substantially optically transmissive material applied in forming at least one transmissive element, wherein said at least one transmissive element is to be arranged substantially along or around the border such as the perimeter of a touch area on which a touch is to be detected, so that when in use, the light couples from each emitter to the transmissive material of the at least one transmissive element, enters the free space therefrom, propagates in the free space on the touch area and reaches, upon absence of touch action interrupting the light propagation, the transmissive material and couples therefrom to the corresponding detector.

In one embodiment, the at least one transmissive element includes exactly one transmissive element that hosts multiple optoelectronic elements such as emitters and/or detectors.

In one, either supplementary or alternative embodiment, the electrical wiring, such as conductors, may be printed or otherwise formed on a flex film substrate or other type of flex or rigid substrate. The optoelectrical components such as the emitters and detectors may be then attached to the film or other type of substrate.

Alternatively, the electrical components, such as the support electronics, emitters, and/or detectors, may be laminated into a multi-layer film structure, for instance.

Finally, the transmissive material of the transmissive element, such as plastic, may be molded, laminated or otherwise arranged onto the film, film structure or other type of a substrate. E.g. in connection with lamination, one or more recesses, cavi- ties, or holes may have been first arranged on the surface of the transmissive element facing the components for accommodating at least the optically active portion of the components to facilitate lossless optical coupling therewith.

Optionally, the transmissive element may be further provided with coating and/or a covering element such as a housing element, which may have been assigned with a number of functions such as protective, concealing and/or aesthetic functions.

In some embodiments, a substrate, e.g. the flex film, may be provided with electronics thereon, said electronics including the support electronics and/or further elec- tronic components like the optoelectronic emitters and detectors, and used as an insert in the injection moulding process during which the transmissive material of the transmissive element is over-molded onto the electronics and the related substrate surface. Advantageously one or more coupling entities, such as connectors or contacts, which may have been already provided on the substrate to connect the ar- rangement to external elements, such as a main board of the host device, are not completely over- molded, or are at least cleared afterwards.

As alluded hereinbefore, the utility of the different aspects of the present invention arises from a plurality of issues depending on each particular embodiment. The manufacturing costs for producing the touch screen arrangement in accordance with the present invention may be kept low due to rather extensive use of affordable and easily obtainable materials, components, and process technology. The feasible process technology also enables rapid industrial scale manufacturing of the arrangement in addition to mere prototyping scenarios. The arrangement may be kept thin, light, and energy conserving in order to suit most use scenarios with little modifications to the surrounding elements and designs. The coupling losses between the emitters and the detectors may be minimized as separate, typically lossy light fun- neling or coupling means such as gratings are not necessary. Indeed, optoelectronic components such as light emitters and detectors may be "immersed" in, i.e. positioned within, the transmissive material by molding or lamination, for example. The components may thus directly optically couple to the transmissive material and vice versa. Thus, in many cases the use of reflective structures and lenses for redirecting and coupling light may be avoided.

The touch detection capability of the various embodiments of the arrangement is good and even multi-touch applications may be constructed. The arrangement may be easily combined with an existing display or device layout, and conveniently con- nected to an external target entity such as a host device mainboard via a flex cable, for example, which also enables easy replacement thereof in the future. The arrangement may further be made robust towards external impacts, depending on the used materials, in which case the arrangement also function as an optionally replaceable screen cover for the underlying display element.

The expression "a number of may herein refer to any positive integer starting from one (1), e.g. one, two, or three. The expression "a plurality of may refer to any positive integer starting from two (2), e.g. two, three, or four. BRIEF DESCRIPTION OF THE RELATED DRAWINGS

Next, the embodiments of the present invention are more closely reviewed with reference to the attached drawings, wherein Fig. 1 illustrates the basic principle of free space touchscreens.

Fig. lb illustrates an example of a free space touchscreen arrangement with multiple emitters and detectors disposed along the sides of a touch area of a display.

Fig. 2a illustrates one embodiment of the present invention.

Fig. 2b illustrates an exemplary cross-section along the line A - A of the embodi- ment type shown in Figure 2a.

Fig. 3a generally illustrates one embodiment for manufacturing the touchscreen arrangement of the present invention.

Fig. 3b is a flow diagram of an embodiment for manufacturing the touchscreen arrangement of the present invention.

Fig. 4 illustrates top and bottom views of one embodiment of the touchscreen arrangement in accordance with the present invention.

Fig. 5a is a block diagram of one embodiment of an apparatus comprising the touchscreen arrangement in accordance with the present invention. Fig. 5b is a block diagram of one embodiment of the touchscreen arrangement according to the present invention.

Fig. 6 shows timing diagrams for two embodiments of sequentially driving the emitters and detectors of the touchscreen arrangement in accordance with the pre- sent invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Figures la and lb were already contemplated hereinbefore in connection with the review of the background of the invention.

Now referring to Figure 2a, a perspective view 202 of one embodiment of the touchscreen arrangement is sketched. It shall be noted that the principles set forth hereinafter may also be clearly applied to other type of touch-based control input devices, such as touch pads, by a skilled person.

The touchscreen arrangement, which may be implemented as a factory- or retrofitted overlay frame for a display, comprises a substrate such as a (flexible) film 206 accommodating electronics 204 such as support electronics like conductors and/or control circuitry, optoelectronic components including light emitter(s) and detectors), and optionally other components. The transmissive element 208 has been provided on the substrate 206. In the illustrated case, the transmissive element 208 defines a rectangular frame shape with a through hole substantially in the middle, and it may accommodate at least a portion of each emitter and detector, for instance. A free space 212b may be thus formed between the frame edges, i.e. in the middle. The free space 212b may be aligned to match the touch area (touch surface) of the underlying display screen (not shown). The light emitters at least partially embedded within the transmissive element 208 are configured to emit light towards the detectors at the opposite edge of the frame through the free space. The light emitted by the emitters to the free space, either simultaneously or sequentially, for instance, defines the detection plane of the touchscreen, i.e. the plane, which in reality does not have to be strictly planar as the light may be emitted and also detected in all three dimensions, and in which the touch actions are recognized. In addition to portions of the transmissive element that are arranged substantially along or around the edge such as the perimeter, or 'border', of the touch area on which a touch is to be detected and are located substantially on the same plane with the touch area and the related detection plane, the transmissive element may bear a number of other portions that may extend below the level of the touch area/detection plane and/or above it, for example.

As an alternative to a single light-transmissive element incorporating all the emitters and detectors, a plurality of transmissive elements could be utilized instead such that at least one emitter or detector is at least partially embedded in and thus optically coupled to each of them, for example. The plurality of elements and embedded electronics may be still arranged along or around the periphery of the touch area to establish a desired configuration such as rectangular, e.g. square, or other formation enabling spanning the detection plane residing over the touch area with the light transmitted by the embedded emitters according to predetermined criteria, not forgetting the associated reception by the detectors.

In the embodiments of the present invention, the transmissive element may incorpo- rate optically substantially transmissive material such as transparent material as deliberated hereinbefore. For example, the transmittance in relation to the predetermined touch interface-utilized wavelength(s) of light, e.g. infrared wavelengths, may reside within the range of about 80% to about 95%, or it may be even higher. The transmissive element may thus comprise optically functional material that is relatively transmissive, potentially substantially transparent or at least translucent, at some wavelength(s) and optionally translucent or even opaque at some other. The transmissive element may comprise a plurality of materials and/or sub-elements, which may differ as to their optical properties such as transmittance, for instance. In the various embodiments of the present invention, integration may be applied and enhanced such that e.g. the transmissive material 208 is laminated, molded or otherwise disposed onto the electronics on the substrate 206, wherein the provided layer preferably comprises holes or other surface contours for accommodating at least part of the electronics such as optoelectronic components upon and after lamination or other applied transmissive element-establishing process. The transmissive material 208 included in the transmissive element, such as a lightguide, conveys the light between the optoelectronic components and the free space 212b and provides sealing/encapsulation to such components and optionally other underlying or embedded elements, such as electronics, as well.

Alternatively, at least part of the optoelectronic components could be left outside the (laminated) layer, being however located and configured (oriented, for example) so as to remain optically coupled with the layer. The dimensions X, Y, Z of the arrangement may be selected so as to fit each particular manufacturing and use scenario (e.g. host device and display layout) as well as possible. For example, the substrate size could be about 150 mm (X direction) x 150 (Y direction) mm x 125 μηι (Z direction) wherefrom a smaller dedicated portion may be further determined for over-molding, lamination and/or other processes, if desired. The thickness (Z direction) of the substrate may naturally vary depending on the embodiment and reside e.g. within the range of about 50 to 500 μηι, for example. The thickness of the transmissive element 208 may also vary use case - specifically and be about 1 mm - 10 mm, for example, depending on the height of the embedded electronics among other factors.

The shape of the arrangement and its constituents, e.g. the transmissive element 208 and optionally the substrate 206, may be defined on the basis of the used manufac- turing method and desired target shape(s). The illustrated, however merely exemplary, arrangement has substantially a rectangular (cuboid) shape, which works particularly well e.g. with roll-to-roll manufacturing methods and with typical display applications, but also e.g. round(ed) shapes are possible and achievable via proper cutting, for instance. Still in the illustrated example, the edges parallel to the Y-axis have been slightly bent downwards, i.e. along Z-axis, to better fit the target apparatus, which could be a mobile terminal, a PDA (personal digital assistant), a music player, a multimedia player, or an industrial electronics and/or automation device, for example. Figure 2b discloses an exemplary cross-section along the line A - A of the embodiment shown in Figure 2a. In this example the transmissive element 208 covers at least most of the substrate's 206 surface onto which the electronics 204 including the emitter(s) 204a, detector(s) 204b and optionally various support electronics have been provided. The emitters 204a/detectors 204b may be located in the recesses or holes of the transmissive element 208 formed in the surface portion facing the substrate during the embedding phase or prior to that. These optoelectronic components and the related transmissive element(s) may be located such that they basically surround, at least to a desired extent, the touch area to provide a detection plane with sufficient detection resolution thereon. The emitter 204a is configured to emit light through the transmissive material of transmissive element 208 to the free space 212b, wherein the light 214 propagates to the opposing side of the space and enters the opposing side transmissive element 208, which may in some embodiments be part of the integral transmissive element frame as contemplated hereinbefore, and reaches the light-sensitive detector 204b. In case a touch action is performed by a finger 212 or stylus, for example, by touching the predetermined touch area 212c of the display or e.g. touch pad, a light ray 214 is at least partially blocked and prevented from reaching the detector 204b configured to monitor the incoming light. The low intensity of the received light may be converted into touch detection, and vice versa.

In the visualized case, the carrier 216 on which the substrate 206, electronics 204a, 204b and transmissive element 208 are located may be a separate carrier, or e.g. the screen border areas outside the desired touch area 212c may be applied as carrier material. This is indicated in the figure by the dotted vertical lines. In some embodiments the dedicated substrate 206 may be omitted and e.g. the carrier 216 may act as a substrate and confront the electronics 204a, 204b and the transmissive element 208.

In one embodiment two rows of emitters may be located in the transmissive element 208 such that one row comprising a number of emitters is embedded in the edge parallel to YZ plane and the other row comprising a number of emitters is embedded in the edge parallel to XZ plane in Figure 1 , and two rows of detectors be simi- larly located relative to the opposite neighboring edges so that the light emitted by a predetermined emitter is captured by one or more predetermined detectors inside the opposite edge.

In other embodiments, at least some of the emitters 204a and/or detectors 204b may be positioned otherwise. For example, they 210 may be located radially such that the detector formation of one or more detectors has a certain first radius (distance) from a predetermined center point or line, whereas one or more emitters have another, second radius relative to the same reference. In the case of angular transmissive element, the detectors 204a/emitters 204b may also be located near the vertices (-corner points) thereof. In one embodiment of a desired touchscreen or other control input arrangement at least one emitter such as a LED or OLED may be positioned in a middle of a target structure and a number of, preferably a plurality of, detectors are disposed around the at least one emitter. The properties of the substrate (a thin film or a thicker substrate) may be selected such that the light behaves in a predetermined, desired manner at the transmissive element-substrate interface. In one embodiment one or more optical properties such as refractive indexes of the substrate and the transmissive element (e.g. in the role of a lightguide) are selected about the same so that the light propagating within the lightguide under TI condition does not substantially react to the interface. In another embodiment, said one or more optical properties of the substrate and light- guide, e.g. the refractive index, are selected such that the TIR-propagating light is reflected, preferably as much as possible, from the lightguide-substrate interface. Alternatively, if the substrate 206 is not used or the interface thereof with the trans- missive element 208 is optically substantially transparent, the material of the carrier 216 may be selected on the basis of TIR propagation, for example. In any case, when the touchscreen frame arrangement comprising either an integrated frame structure or a plurality of separately locatable parts is disposed relative to a display, which is indeed a typical use scenario, the dimensions, materials, and naturally positioning of the associated elements are preferably selected such that the whole touch area is spanned by the emitters (light) according to the desired design rules such as the desired touch detection resolution that may be location-dependent.

In the illustrated case, the whole exposed surface area of the display between the transmission and reception side transmissive elements or element portions 208 belongs to the touch area 212c, but in other embodiments, there may also reside pas- sive, or 'dead', zone between the transmissive material walls, or 'edges', 208 and the touch area 212c. In that case the touch area 212c may be centrally positioned and the surrounding surface area thus adjacent both to the central touch area 212c and the transmissive edges 208 may be the passive areas. In that case, the transmissive element(s) are located around both the centrally positioned touch area and the surrounding passive area.

Figure 3a depicts, in a very general sense, one embodiment for manufacturing the touchscreen arrangement of the present invention. In phase 302 a substrate is provided with the necessary electronics 302b such as conductors, detectors, emitters, and necessary control circuitry, which is illustrated by a rotating arm or nozzle working on the substrate surface. The arm could belong to a flip-chip bonding apparatus or inkjet printer, for example. In phase 304 the transmissive element such as a lightguide element is arranged onto the substrate/electronics aggregate by molding or lamination, for instance. At least part of the electronics are thus preferably "im- mersed" in the transmissive material, for instance located in the recesses thereof, that thus encapsulates the aforementioned part, which may be seen in phase 306 representing one embodiment of the touchscreen arrangement capable of being used e.g. as a display overlay frame. Further, any excessive substrate material may be cut off, if needed (not shown in the figure). The overlay may be ready- fitted such as factory-fitted to a host device (housing) or provided upon the display thereof and functionally coupled thereto only when needed. Figure 3b is a more detailed flow diagram of one embodiment for manufacturing the touchscreen arrangement of the present invention.

At 309, referring to a start-up phase, the necessary tasks such as material, component and device selection and acquisition take place. In determining the emitter and sensor types or e.g. other electronics and substrate/transmissive element/conductor materials and shapes, specific care must be taken that the individual elements and material selections work together and survive the selected manufacturing process of the overall arrangement, which is naturally preferably checked upfront on the basis of the manufacturing process vs. component data sheets, or by an- alyzing the produced prototypes, for example.

The reference numeral 322 generally refers to manufacturing phases during which the initial substrate is provided with electronics comprising e.g. the support electronics for driving the optoelectronic elements etc. and the actual optoelectronic el- ements. The resulting aggregate substrate may be a multilayer film comprising the aforesaid electronics and elements spread between different layers thereof. The internal phases 310 and 312 may be executed in a varying order that best fits the particular use scenario in question. Further, the internal tasks of shown phases may be reallocated between the phases 310, 312, if considered advantageous.

The used substrate may include, for example, polymers such as a PET or PC film. An applicable substrate shall be generally selected such that the desired flexibility, robustness, and other requirements like adhesion properties in view of the electronics and the lightguide material, or e.g. in view of available manufacturing tech- niques, are met.

The selected substrate may also be preconditioned prior to and/or during the illustrated processing phases. The substrate may be preconditioned to increase adhesion with other materials such as laminated, glued or injection-moulded lightguide plas- tics, for example.

In 310 the support electronics, such as electrical conductors and circuitry, may be printed or otherwise formed onto the substrate, on one or more (e.g. predetermined top and/or bottom, when in use) side faces. Feasible techniques for providing the electronics generally include screen printing, rotary screen printing, gravure printing, flexography, ink-jet printing, tampo printing, etching (like with PWB- substrates), transfer-laminating, thin-film deposition, etc.

For instance, in the context of conductive pastes, silver-based PTF (Polymer Thick Film) paste could be utilized for screen printing the circuit design on the substrate. Also e.g. copper or carbon-based PTF pastes may be used. Alternatively, copper/aluminum layers may be obtained by etching. In a further alternative, conduc- tive LTCC (low temperature co-fired ceramic) or HTCC (high temperature co-fired ceramic) pastes may be sintered onto the substrate. One shall take into account the properties of the substrate when selecting the material for conductors. For example, sintering temperature of LTCC pastes may be about 850 to 900°C, which may require using ceramic substrates. Further, silver/gold-based nanoparticle inks could be used for producing the conductors.

Reverting to the feasible printing techniques, the paste/ink shall be selected in connection with the printing technique and the substrate material because different printing techniques require different rheological properties from the used ink/paste, for instance. Further, different printing technologies provide varying amounts of ink/paste per time unit, which often affects the achievable conductivity figures.

Electronic SMT components and circuits or (flip) chips may be attached to the substrate by adhesive, such as an epoxy adhesive, for example. Both conductive (for enabling electrical contact) and non-conductive (for mere fixing) adhesives may be utilized. Such elements are preferably selected so as to withstand the pressure and temperature of the utilized transmissive element-establishing process such as lamination or injection over-molding process. Alternatively or additionally, the trans- missive element may established by applying a sheet or film of suitable material, e.g. glass or plastic material, which is disposed onto the substrate and, for example, glued and/or otherwise fixed thereto. The materials, such as the lightguide materials), utilized in accordance with the embodiments of the present invention may include epoxy and/or sol-gel or corresponding, potentially molded, materials. In 312 the optoelectronic elements including the light emitter(s) and detector(s) are bonded with the substrate by adhesive, for example. Accordingly, suitable printing technologies may be exploited. E.g. OLEDs and/or photo-sensitive detector structures may be printed on the substrate by an inkjet printer or other applicable de- vice(s). The light emitters and detectors are configured to emit and detect, respectively, predetermined wavelengths of electromagnetic radiation, e.g. visible wavelengths and/or, in many use cases preferred, non-visible wavelengths such as infrared wavelengths.

A person skilled in the art will appreciate the fact that the provision of optoelectronic and other electrical elements on the substrate may in various other embodiments of the present invention split also differently, if at all, between the illustrated and merely exemplary stages 310 and 312, and the related number of production stages may be adapted accordingly. For example, most of the components, including both the support components and the optoelectronic components, may be added to the already formed circuit model of mere conductors substantially during the same production stage or in multiple subsequent stages. One shall also remember in the light of the foregoing that, instead of a dedicated substrate, some applicable physical structure such as screen border area or portion of a device cover may act as a substrate for electronics and/or the transmissive element potentially already comprising at least partially embedded electronics such as optoelectronic components in some embodiments.

The use of advantageously flexible materials preferably enables carrying out at least some of the items 322, 310, 312, or further items, by roll-to-roll methods, which may provide additional benefits time-, cost- and even space-wise considering e.g. transportation and storage. In roll-to-roll, or 'reel-to-reel', methods the desired ele- ments, such as optical and/or electrical ones, may be deposited on a continuous 'roll' substrate, which may be both long and wide, advancing either in constant or dynamic speed from a source roll, or a plurality of source rolls, to a destination roll during the procedure. Thus the substrate may thus comprise multiple products that are to be cut separate later. The roll-to-roll manufacturing advantageously enables rapid and cost effective manufacturing of products also in accordance with the present invention. During the roll-to-roll process several material layers may be joined together On the fly', and the aforesaid elements such as electronics may be structured on them prior to, upon, or after the actual joining instant. The source layers and the resulting band-like aggregate entity may be further subjected to various treatments during the process. Layer thicknesses (thinner layers such as 'films' are generally preferred in facilitating roll-to-roll processing) and optionally also other properties should be selected so as to enable roll-to-roll processing to a preferred extent. In 314 the transmissive element is formed on the substrate such that at least portion of the electronics is "immersed" therein, e.g. in the readymade or real-time shaping recesses. Thereby, the transmissive element may act as a cover for the electronics and as a light-transporting medium between the optoelectronics and the free space comprising the detection plane over the touch area.

In one embodiment the transmissive element comprises plastic material such as PC that is laminated, (over-)molded or otherwise disposed onto the substrate like a thermoplastic polymer film, e.g. a PET film, having electronics already provided thereon. During molding, the substrate may be applied as an insert into the mold of the injection moulding apparatus so that the PET is cast upon the substrate. The provided material and the used attachment method shall be preferably selected such that the electronics on the substrate remain unharmed during the process, while the material is properly attached to the substrate and the optical properties thereof are as desired.

In 316 and 320 it may be checked whether further processing of the lightguide- substrate aggregate is required, and if this is the case, the necessary steps are taken, respectively. For example, supplementary material layers may be added to the touchscreen arrangement. In one embodiment, at least part of the arrangement, such as (a portion of) the transmissive element, may be provided with a hard-coating that protects against scratches. Additionally or alternatively, other functional or decorative layers, elements and/or treatments may be provided, such as a layer for enhanc- ing the feel of the touch surface from the standpoint of the user. Further, step 318 may refer to coupling additional and/or external elements such as connectors or (flex) cables to the arrangement, and/or even to disposing the ready or only partially finished arrangement in the target product or device such as a mobile terminal, a computer (display) or a control display. Alternatively, the arrangement may be at least partially constructed directly on its destination location, e.g. within host device or other entity. Yet, different quality checks and tests concerning the functioning of the laminated or over-molded (or otherwise established/processed) elements, the transmissive element and/or remaining entities may be performed. It is to be understood that phase 316 may not necessarily refer to a real-time check e.g. on the basis of a real-time monitored property of the arrangement such as the functioning of the electronics or lightguide, as the 'check' may also refer to a predetermined process control parameter value (e.g. add hard-coating=T UE) coded in the process control data, which is then used to define the treatment whereto the arrangement is subjected.

In phase 318 the method execution ends and the obtained touchscreen arrange - ment(s) may be transported forward.

Figure 4 illustrates top and bottom views of one embodiment of the touchscreen arrangement's layout outline in accordance with the present invention. In item 402 a 'top' view is shown and in item 404 a bottom view is shown. The conductors, con- nectors, chips, and other components are recognizable in the figure, wherein the emitter/detector arrays surround a rectangular, substantially a square, touch screen window (through hole enabling creating the free space with detection plane for touch actions) to be used as a touch area overlay frame for a display screen, for example.

Fig. 5a is a general block diagram of one embodiment of an apparatus 501 comprising a touchscreen (and/or a touchpad) arrangement in accordance with the present invention. The apparatus may include or be a mobile terminal, a PDA, a control device for industrial applications, a multi-purpose computer (desktop/laptop/palmtop), etc. As being clear to a skilled person, various elements of the apparatus 501 may be directly integrated in the same housing or provided at least with functional connectivity, e.g. wired or wireless connectivity, with each other. For instance, a display 514 and the associated touchscreen arrangement 502 may be incorporated in the apparatus 501 as integrated or separate, or at least separable, elements.

One potential, if not elementary, functional element that is included in the apparatus is memory 506, which may be divided between one or more physical memory chips and/or cards, may comprise necessary code, e.g. in a form of a computer program/application, for enabling the control and operation of the apparatus, and fur- ther comprise other data, e.g. current settings and user data. The memory 506 may include e.g. ROM (read only memory) or RAM -type (random access memory) implementations. The memory 506 may further refer to an advantageously detachable memory card/stick, a floppy disc, an optical disc, such as a CD-ROM, or a fixed/removable hard drive.

A processing means 504, e.g. a processing/controlling unit such as a microprocessor, a DSP (digital signal processor), a micro-controller or programmable logic chip(s), optionally comprising a plurality of co-operating or parallel (sub-)units, may be needed for the actual execution of the application code that may be stored in memory 506. Display 514 and keyboard/keypad 512 or other supplementary control input means, such as keys, buttons, knobs, voice control interface, sliders, rocker switches, etc, may provide the user of the apparatus 501 with data visualization means and control input means in addition to the touchscreen UI (user interface) 502 in connection with the display 514. The processor 504 may control the touchscreen arrangement 502, or a specific control means may be alternatively or additionally provided for the purpose. Data interface 508, e.g. a wireless transceiver (GSM (Global System for Mobile Communications), UMTS (Universal Mobile Telecommunications System), WLAN (Wireless Local Area Network), Bluetooth, infrared, etc), and/or an interface for a fixed/wired connection, such as an USB (Universal Serial Bus) port, a LAN (e.g. Ethernet) interface, or Firewire-compliant (e.g. IEEE 1394) interface, is typically required for communication with other devices. The apparatus may include various supplementary elements 510 that can be used with the touchscreen arrangement 502, for instance. It is self-evident that further functionalities may be added to the apparatus and the aforesaid functionalities may be modified depending on each particular embodiment.

Fig. 5b is a block diagram of one embodiment of the touchscreen arrangement 502 according to the present invention. The touchscreen arrangement may in practice include own, external, and/or shared control or other means, such as processor 524, in view of the rest of the apparatus 501 or a similar host system. For example, the processor 504 could control also the touchscreen 502, i.e. processor 504=524, if provided with necessary connection to the support electronics of the light- guide/substrate arrangement.

The arrangement 502 may comprise a controller switch, e.g. a 'demultiplexer', 516 that drives the emitters of the actual touch screen overlay frame 522, i.e. the functional part defining the free space providing user access to the touch area, and the emitter/detector arrays or other patterns, and is controlled by processor 524, which may additionally or alternatively refer to a shared unit 504 controlling also other functions of the apparatus 501 as deliberated above. The provided control is illustrated as LED SELector and LED D iVer signals. Also the detectors may be controlled by the processor 524 or some other processing means e.g. via a multiplexer switch 518. The provided control is illustrated as DETECTOR SELECT signal. The obtained detector signal(s) such as the illustrated SIGNAL DATA signal may be preprocessed such as amplified, filtered, and/or A/D-converted 520 prior to forwarding to the processor 524 or some other processing means like processor 504. The illustrated functional elements may comprise further connections, e.g. via connectors or conductors possibly including data cables, to elements that are external to the touch screen arrangement or implemented on the same substrate. One such connection has been illustrated as POSITION OUT in the figure.

A person skilled in the art will appreciate that the functionalities of the visualized blocks in Figures 5a and 5b may be in practical circumstances split differently between the shown and/or other entities depending on the embodiment. Generally, software for controlling the arrangement or controlling the manufacturing of the ar- rangement, and comprising code means that are executable on a computer, may be provided on a carrier medium, such as memory card or optical disc, or be transmitted over a communications connection or communications network.

Figure 6 depicts few merely exemplary timing diagrams of two embodiments for sequentially driving the emitters and detectors of the touchscreen arrangement. In the example marked with a reference numeral 602 a LED, or other type of an emitter, and a corresponding detector, such as a phototransistor or photodiode, are active substantially simultaneously as visualized by the control signals' up and down portions. The emitter/detector pairs are sequentially activated in a continuous manner such that only one pair is active at a time. This is done for detecting and locating the touches.

As a concretized example, a channel may be defined as an emitter-detector -pair in X- or Y-direction, wherein X and Y define two orthogonal axes, each of which be- ing parallel with two borderlines of a rectangular touch surface area (-window) 606 surrounded by the emitters and detectors. Signal on a certain, location-dependent channel is then based on the intensity level of light emitted by a certain emitter and detected at a corresponding detector. In the illustrated there are three emitters and detectors disposed parallel to the X and Y axes on the opposite sides of the touch area 606, which is illustrated via the vertical and horizontal broken lines denoting 'channels' spanning the detection plane across the touch surface, respectively.

By keeping all the emitters and detectors constantly on and given a touch on an area associated with the certain channel, which links to a certain touch surface 'strip' ex- tending between the certain emitter and the corresponding detector on the overall touch area, the detector may still capture exceedingly lot of light from other active emitters, which naturally reduces the touch recognition and localization capability and the sensitivity of the arrangement. Thus, the emitters may be pulsed e.g. on a channel-by-channel basis:

• Turn on the LED XI for a time tp, and read the signal at sensor XI simulta- neously

apply latency for a time period tl, if needed

• Turn on the LED X2 for a time tp, and read the signal at sensor X2 simultaneously

apply latency for a time period tl if needed

·

• Turn on the LED Yl for a time tp, and read the signal at sensor Yl simultaneously

• If decisive signal attenuation is detected relative to a channel crossing (Xt , Yt), the touch location on the touch area can be programmatically mapped to a corresponding point and e.g. associated feature on the related display. Also, multiple crossings can be mapped to discrete multiple simultaneous touches (multi-touch function) or a touch by a large finger or stylus.

Typical rise/fall times of optoelectronic components may be of the order of few microseconds. Thus, the pulse times less than about 0.5 ms are relatively easily attained in terms of hardware. In a tested example set-up (12 channels), the overall time for one whole sequence could be pushed to less than about 0.01 s. This is fast enough for most applications.

In the example marked with a reference numeral 604,'cross-talk' sequencing is used wherein one LED is associated with a plurality of, in this example three, detectors, i.e. the one that is actually opposing the LED, i.e. the 'main' detector, and the two adjacent ones. During the sequencing and active portion of a certain emitter, the detection signals of the associated three detectors may be then sequentially read as shown prior to moving into a next group of an emitter and three detectors. Some detectors may be associated with a plurality of emitters, i.e. the groups overlap relative to the detectors. By this procedure, the obtained resolution can be doubled in both directions (X/Y) at least on areas near the screen center because both temporal and positional distribution of light as captured by detectors (-local temporal intensity level at each detector of the group) is available for analysis. Further group configurations (e.g. multiple emitters -multiple detectors per group) are also possible. In addition to touch recognition and localization aspects, touch intensity or pressure, i.e. how hard the finger or stylus is pressed upon the touch area, may be monitored for additional control of the target device. The pressure may be deduced from the amount and optionally nature of the light intensity loss (i.e. more loss indicates more touch pressure) at a detector, for example.

Considering the present invention in the light of the related process parameters and set-up, few further guidelines can be given on the basis of conducted tests. When the substrate is PET and the transmissive element plastics to be, for example, over- molded thereon is PC, the temperature of the melted PC may be about 280 to 320°C and mould temperature about 20 to 95°C, e.g. about 80°C. The used substrate (film) and the process parameters shall be selected such that the substrate does not melt and remains substantially solid during the process. The substrate shall be positioned in the mold such that it remains properly fixed. Likewise, the preinstalled electronics shall be attached to the substrate such that they remain static during the molding.

The detector(s) may be protected from external unwanted light (e.g. sunlight or display lighting, generally ambient light) by a blocking structure.

The scope of the invention is determined by the attached claims together with the equivalents thereof. The skilled persons will again appreciate the fact that the explicitly disclosed embodiments were constructed for illustrative purposes only, and the scope will cover further embodiments, embodiment combinations, variations and equivalents that better suit each particular use case of the invention. For example, in some scenarios merely the support electronics, or a part thereof, and/or part of the emitters/detectors may be covered by the transmissive material. In that case the remaining (parts of the) emitters/detectors could be located elsewhere, preferably still on the substrate, such that they are at least optically coupled to the trans- missive element. The coupling could occur directly between the emitters/detectors and the transmissive element (e.g. with a small gap or direct contact between the emitters/detectors and the element), or via dedicated incoupling and/or outcoupling structures such as gratings. Further, in some embodiments the touch area may be formed of almost any kind of a surface that may be touched and supplemented with the suggested user input arrangement, with reference to table or floor surfaces, for instance. Thus, any dedicat- ed display surfaces, touchpad or generally touch input surfaces are not necessary to implement an input device by the arrangement disclosed herein.

Claims

Claims

1. A free space light propagation-based user input arrangement (202, 502), such as a user input arrangement of a touchscreen or a touchpad, comprising a number of light emitters (204, 204a, 302b) and corresponding detectors (204, 204b, 302b) configured to transmit light and detect the transmitted light, respectively, the light to be transmitted and detected optionally being or at least including infrared or ultraviolet region light, at least one transmissive element (208, 308) comprising optically substantially transmissive material such as optically substantially transparent material, wherein said at least one transmissive element is to be arranged substantially along or around the edge such as the perimeter of a touch area (212c) on which a touch is to be de- tected, and wherein the emitters and detectors of said number have been at least partially embedded in the transmissive material of the at least one transmissive element such that, when in use, the light couples from each emitter to the transmissive material of the at least one transmissive element, enters the free space (212b) therefrom, propagates in the free space on the touch area and reaches, upon no touch action in the free space interrupting the light propagation, the transmissive material and couples therefrom to the corresponding detector.

2. The arrangement of claim 1, wherein said at least one transmissive element includes transmissive material molded or laminated onto at least one emitter or detector.

3. The arrangement of any preceding claim, comprising at least one substrate (206) onto which said number of emitters and detectors have been disposed or established optionally through utilization a of printed electronics technique such as inkjet printing.

4. The arrangement of claim 3, wherein the at least one substrate includes a substrate film preferably of plastic material.

5. The arrangement of any of claims 3-4, wherein the substrate is a multilayer substrate comprising the support electronics, emitters and detectors as spread between at least two layers thereof.

6. The arrangement of any preceding claim, wherein the transmissive element surface that faces at least one emitter or detector, and optionally the substrate thereof, is provided with a recess or hole for accommodating at least portion of said at least one emitter or detector.

7. The arrangement of any preceding claim, wherein the configuration enables recognizing the touch, optionally locating the touch and further optionally determining the touch pressure, based on the touch-induced change, such as drop, in the signal level indicative of light intensity and/or distribution as captured by one or more detectors in contrast to a predetermined or adaptively determined basic level indica- tive of the reception intensity and/or distribution during a non- touch condition.

8. The arrangement of any preceding claim, wherein the emitters include at least one LED (light emitting diode) or OLED (organic LED).

9. The arrangement of any preceding claim, wherein the detectors include at least one element selected from the group consisting of: a photodiode, a phototran- sistor, a printed photo-sensitive detector element, and an image sensor.

10. The arrangement of any preceding claim, comprising a plurality of emitters and detectors in said number of emitters and detectors configured to sequentially activate and deactivate (604) in groups such that in one group at least one emitter is associated with a plurality of detectors to increase the resolution in locating the touch relative to the touch area.

1 1. An electronic apparatus (501) comprising the arrangement of any preceding claim and optionally comprising a display and/or a touchpad associated with the arrangement defining the touch area (606), wherein said apparatus further optionally comprises one element selected from the group consisting of: a mobile terminal, a personal digital assistant, a music player, a multimedia player, a portable computer, a desktop computer, a palmtop computer, a wristop computer, a portable radio, and a control device for an industrial application.

12. A system comprising the arrangement of any of claims 1-10 and an element defining the touch area (606) optionally provided with a protective material layer or a layer configured to improve the touch feel optionally affecting the actuation element's such as finger's or stylus' slide on the touch area preferably by friction.

13. A method for manufacturing an arrangement for a user input device, such as a touchscreen or a touchpad, comprising:

-obtaining a number of light emitters and corresponding detectors (302, 309, 322, 312) for transmitting light and detecting the transmitted light, respectively, the light optionally being infrared or ultraviolet region light, and

-embedding (304, 314), optionally by molding or lamination, at least partially said emitters and detectors in optically substantially transmissive material applied in forming at least one transmissive element (208, 308), wherein said at least one transmissive element is to be arranged substantially along or around the border such as the perimeter of a touch area on which a touch is to be detected so that when in use, the light couples from each emitter to the transmissive material of the at least one transmissive element, enters the free space therefrom, propagates in the free space on the touch area and reaches, upon absence of touch action interrupting the light propagation, the transmissive material and couples therefrom to the corresponding detector.