LAMINATED LIGHT SOURCE HAVING A LOW-DENSITY SET OF LIGHT-EMITTING ELEMENTS
An inventive light source includes a rigid layer, a polymer layer, and a set of multiple light-emitting elements. The polymer layer is attached to the rigid layer to form a laminated structure that is transparent for visible light. The set of multiple light-emitting elements is positioned between the rigid layer and the polymer layer. Each light-emitting element includes one or more inorganic microLEDs that are arranged to generate and emit output light to propagate out-of-plane relative to a corresponding localized area of the laminated structure surrounding that light-emitting element. Each light-emitting element of the set is sufficiently small in at least one transverse dimension, and the light-emitting elements occupy a sufficiently small fraction of an areal extent of the set, so as to enable visual observation of a scene through the laminated structure along a sight line that passes through the set of light-emitting elements.
1 . A light source comprising:
a rigid layer;
a polymer layer attached to the rigid layer, the rigid layer and the polymer layer forming a laminated structure that is transparent for visible light; and
a set of multiple light-emitting elements positioned between the rigid layer and the polymer layer, each light-emitting element comprising one or more inorganic microLEDs that are arranged to generate and emit output light to propagate out-of-plane relative to a corresponding localized area of the laminated structure surrounding that light-emitting element,
each light-emitting element of the set being sufficiently small in at least one transverse dimension, and the light-emitting elements occupying a sufficiently small fraction of an areal extent of the set, so as to enable visual observation of a scene through the laminated structure along a sight line that passes through the set of light-emitting elements.
2 . The light source of claim 1 , each light-emitting element of the set including multiple microLEDs, each microLED of a given light-emitting element being arranged and connected so as to be operable independently of at least one other microLED of that light-emitting element.
3 . The light source of claim 1 , each light-emitting element of the set including only a single microLED.
4 . The light source of claim 1 , each light-emitting element of the set being arranged and connected so as to be operable independently of at least one other light-emitting element of the set.
5 . The light source of claim 1 , each light-emitting element comprising one or more direct-emitting or phosphor-converted inorganic semiconductor microLEDs, the microLEDs including one or more UV-, visible-, or infrared-emitting microLEDs, each microLED including one or more materials among III-V, II-VI, or Group IV semiconductor materials.
6 . The light source of claim 1 , one or more of the light-emitting elements including corresponding wavelength-converting structures.
7 . The light source of claim 1 further comprising multiple electrically conductive traces on or within the polymer layer that are arranged and connected for providing electrical drive current to the light-emitting elements of the set, the traces being sufficiently transparent, sufficiently narrow, or spaced sufficiently far apart so as to enable visual observation of the scene through the laminated structure along the sight line that passes through the set of light-emitting elements.
8 . The light source of claim 1 , each light-emitting element having a largest transverse dimension that is less than 200 μm.
9 . The light source of claim 1 , the light-emitting elements occupying less than 25% of the areal extent of the set.
10 . The light source of claim 1 , the set of light-emitting elements occupying an area of the laminated structure having a smallest transverse dimension that is greater than 5 mm.
11 . The light source of claim 1 further comprising an adhesive layer between the rigid layer and the polymer layer, the adhesive layer adhering together the rigid layer and the polymer layer and at least partly encapsulating the set of light-emitting elements, the adhesive layer being transparent for visible light.
12 . The light source of claim 1 , the entire rigid layer being planar.
13 . The light source of claim 1 , the rigid layer including one or more areal regions that are curved, or two or more planar areal regions that are not coplanar with respect to one another.
14 . The light source of claim 1 , the polymer layer being flexible.
15 . The light source of claim 1 , the polymer layer comprising a rigid layer of cured or cross-linked polymer material.
16 . The light source of claim 1 , (i) the polymer layer including one or more polymeric materials among clear polyimide (PI), polyethylene naphthalate (PEN), polyethylene terephthalate (PET), or other flexible or curable or cross-linked transparent polymer, or (ii) the rigid layer including one or more materials among silica, optical glasses, polycarbonate, polymethylmethacrylate (PMMA), or other rigid transparent polymers.
17 . The light source of claim 1 , each light-emitting element being sufficiently small in at least one transverse dimension, and the light-emitting elements of the set being spaced sufficiently far apart, so that, with the light-emitting elements in an off state or emitting only non-visible light, the set does not substantially interfere with visual observation of the scene through or reflected by the substrate by a naked eye of a human observer along the sight line that passes through the set.
18 . The light source of claim 1 , each light-emitting element being sufficiently small in at least one transverse dimension, and the light-emitting elements of the set being spaced sufficiently far apart, so that to a naked eye of a human observer the set is only negligibly visible when in an off state or when emitting only non-visible light.
19 . The light source of claim 1 , each light-emitting element being sufficiently small in at least one transverse dimension, and the light-emitting elements of the set being spaced sufficiently far apart, so that to a naked eye of a human observer the set resembles dust on the laminated structure when in an off state or when emitting only non-visible light.
20 . A method comprising, with a laminated structure positioned in a sight line along which a scene is observed through the laminated structure by an observer, the laminated structure being transparent for visible light and comprising a rigid layer and a polymer layer attached to the rigid layer, operating a set of multiple light-emitting elements positioned between the polymer layer and the rigid layer to emit output light,
each light-emitting element comprising one or more light emitters that are arranged to generate and emit the output light to propagate out-of-plane relative to a corresponding localized area of the laminated structure around that light-emitting element, and
each light-emitting element of the set being sufficiently small in at least one transverse dimension, and the light-emitting elements occupying a sufficiently small fraction of an areal extent of the set, so as to enable visual observation of the scene through the laminated structure along the sight line that passes through the set of light-emitting elements.