FIELD OF THE INVENTION

Generally the present invention relates to multilayer structures in connection with electronics, associated devices, and methods of manufacture. In particular, however not exclusively, the present invention concerns provision of integral illumination solution within a multilayer structure.

BACKGROUND

Generally there exists a variety of different stacked assemblies and structures in the context of e.g. electronics and electronic products such as various electronic devices.

The motivation behind stacking electronics and other elements in a common structure may be as diverse as the related use contexts. Relatively often size savings, weight savings, cost savings, usability benefits, or just efficient integration of components in terms of e.g. the manufacturing process or logistics is sought for when the resulting optimized solution ultimately exhibits a multilayer nature. In turn, the associated use scenarios may relate to product packages or food casings, visual design of device housings, wearable electronics, personal electronic devices, displays, detectors or sensors, vehicle interiors, antennae, labels, vehicle and particularly automotive electronics, etc.

Electronics such as electronic components, ICs (integrated circuit) and conductors may be generally provided onto a substrate element by a plurality of different techniques. For example, ready-made electronics such as various surface mount devices (SMD) may be mounted on a substrate surface that ultimately forms an inner or outer interface layer of a multilayer structure. Additionally, technologies falling under the term “printed electronics” may be applied to actually produce electronics directly and additively to the associated substrate. The term “printed” refers in this context to various printing techniques capable of producing electronics/electrical elements from the printed matter, including but not limited to screen printing, flexography, and inkjet printing, through a substantially additive printing process. The used substrates may be flexible and printed materials organic, which is however, not necessarily always the case.

A substrate such as a plastic substrate film, may be subjected to processing, e.g. (thermo) forming or molding. Indeed, using e.g. injection molding a plastic layer may be provided on the film, potentially then embedding a number of elements such as electronic components present on the film. The plastic layer may have different mechanical, optical, electrical, etc. properties. The obtained multilayer, or stacked, structure may be configured for a variety of purposes depending on the included features, such as electronics, and the intended use scenario and related use environment. It may, for instance, comprise connecting features such as fluke type protrusions for coupling with compatible recesses of a host element or vice versa.

Occasionally different elements, surfaces or devices should be provided with illumination capability that may bear e.g. decorative/aesthetic or functional, such as guiding or indicative, motive. For example, the environment of the element or device should be floodlit for increasing visibility in the gloom or dark during night-time, which may, in turn, enable trouble-free performing of various human activities typically requiring relatively high lighting comfort, such as walking or reading, to take place. Alternatively, the illumination could be applied to warn or inform different parties regarding e.g. the status of the host element or connected remote device via different warning or indicator lights. Yet, the illumination might yield the host element a desired appearance and visually emphasize its certain features by providing e.g. brighter areas thereon with desired color. Accordingly, the illumination could also be applied to instruct a user of the device about e.g. the location of different functional features such as keys, switches, touch-sensitive areas, etc. on the device surface, or about the actual function underlying the illuminated feature.

Thus, there are a great number of use cases for illumination in conjunction with different structures and devices. As the illumination may not, however, always be a critical or sole feature of highest priority or of most importance in the associated product, and it may actually be considered a supplementary, optional feature only, the design and implementation of lighting features providing the desired illumination effect shall be duly executed. Weight and size requirements, elevated power consumption, additional design considerations, new process steps, and generally increased overall complexity of the manufacturing phase and the resulting product are all examples of numerous drawbacks easily becoming materialized as a side effect of adopting lighting features in the target solution. Yet, the appearance of the lighting effect and e.g. perceivability of lighting elements is one other issue. In some applications, the light sources should remain hidden or weakly exposed, or the lighting effect should be rather delicate without hotspots.

SUMMARY

An objective of the present invention is to at least alleviate one or more of the above drawbacks associated with the existing solutions in the context of various electronic devices or other host elements that are to be provided with lighting features.

An objective is achieved with the embodiments of a multilayer assembly and a related method of manufacture in accordance with the present invention.

According to one embodiment of the present invention, a multilayer assembly for an electronic device comprises

a preferably flexible substrate film configured to accommodate electronics, such as conductive traces and electronic components, e.g. SMDs (surface-mount device), on at least first side thereof, said film having the first side and a second side,

a number of light sources, preferably LEDs, provided on the first side of the substrate film and configured to emit light of predetermined frequency or frequency band, preferably including or substantially limiting to visible light,

a molded plastic lightguide layer provided onto the first side of the substrate film and at least partially embedding the light sources, the plastic lightguide layer being of optically at least translucent, optionally transparent, material having regard to the predetermined frequency or band, wherein the plastic lightguide layer is configured to transmit light emitted by the embedded light sources so that the transmitted light propagates within the lightguide layer and is outcoupled from the plastic lightguide layer via an outer surface thereof substantially opposite to the embedded light sources, and a masking layer provided on the outer surface of the plastic lightguide layer, containing substantially opaque material to block external view of at least some internals of the multilayer structure including the light sources, wherein the masking layer defines a window for letting the light emitted by the embedded light sources and propagated within the plastic lightguide layer to pass through the masking layer towards the environment,

the light sources, masking layer and related window being mutually configured such that there is no direct line-of-sight (LOS) path at least within a selected viewing angle from outside the assembly, preferably including zero angle from the surface normal of the masking layer, to the light sources and optionally further electronics through the window.

According to one other embodiment, a method of establishing a multilayer assembly for an electronic device comprises

obtaining a preferably flexible substrate film configured to accommodate electronics on at least first side thereof, said film having the first side and a second side,

providing a number of light sources on the first side of the substrate film, said light sources being configured to emit light of predetermined frequency or frequency band,

molding a plastic lightguide layer onto the first side of the substrate and thereby at least partially embedding the light sources, the plastic lightguide layer being of optically at least translucent, optionally transparent, material having regard to the predetermined frequency or band of light, wherein the plastic lightguide layer is configured to transmit light emitted by the embedded light sources so that the transmitted light propagates within the lightguide layer and is outcoupled from the lightguide layer via an outer surface thereof substantially opposite to the embedded light sources, and

providing a masking layer on the outer surface of the lightguide layer containing substantially opaque material to block external view of at least some internals of the multilayer structure including the light sources, wherein the masking layer defines a window for letting the light emitted by the embedded light sources and propagated within the lightguide layer to pass through the masking layer towards the environment, the light sources, masking layer and related window being mutually configured such that there is no direct line-of-sight path at least within a selected viewing angle from outside the assembly to the light sources and optionally further electronics through the window.

A device such as an electronic device comprising an embodiment of the assembly may be provided. The device may be a portable, hand-held, wearable, desktop or other type of a device. It may be of stand-alone type or the device may constitute a part of a larger ensemble with reference to a dashboard of a vehicle, for example.

Different considerations presented herein concerning the embodiments of the assembly may be flexibly applied to the embodiments of the method mutatis mutandis, and vice versa, as being appreciated by a skilled person.

The utility of the present invention arises from a plurality of issues depending on the embodiment.

Lighting features such as light sources and associated optics, guiding layers, lenses, diffusers, collimators, prisms, diffracting elements, reflectors, opaque/masking elements, etc. may be cleverly integrated into a common assembly, which may in turn establish at least part of a host device or host element. The applicable light sources include different printed light sources such as OLEDs and more traditional mountable components such as LEDs, both alike. The illumination effect thus created may bear aesthetic/decorative, indicative, instructive and/or warning functions, for example. By the proper configuration of the light sources, intermediate elements and the window, including e.g. the positioning of the masking layer in relation to the embedded light sources and lightguide layer, the outcoupled light may appear very uniform while the masking layer conceals the hideous electronics such as the light sources from the external viewer.

Yet, the assembly may exhibit a selected appearance or e.g. tactile feel to the viewer such as operator by the configuration of surface graphics, embedded graphics (may still be visible e.g. through the window), surface materials with different surface profiles, general shape, etc.

The obtained structure may be generally kept relatively light, thin and energy efficient. The optical coupling between the embedded optoelectronics such as light sources or sensors and the lightguide may be strong with low loss and without substantial artifacts. Yet, the assembly may be somewhat simple and compact by construction, which usually converts into durability and other assets a well. Relative simplicity of the associated manufacturing process yields benefits own its own with reference to e.g. the related rather tolerable device and material costs, space, process time, logistic and storage requirements.

The used thermoplastic material may be optimized for various purposes including securing electronics in view of the molding process. Yet, the molded material optionally together with other used materials may be configured to protect the embedded elements such as electronics from e.g. environmental conditions such as moisture, heat, cold, dirt, shocks, etc.

The expression “a number of” may herein refer to any positive integer starting from one (1).

The expression “a plurality of” may refer to any positive integer starting from two (2), respectively.

The ordinal numbers such as “first” and “second” are herein used to distinguish one element from other element, and not to specially prioritize or order them, if not otherwise explicitly stated.

The terms “film” and “foil” are herein used generally interchangeably, unless otherwise explicitly indicated.

Different embodiments of the present invention are disclosed in the attached dependent claims.

