EP3388742B1

EP3388742B1 - A method for the production of a housing of a lighting device and corresponding lighting device

Info

Publication number: EP3388742B1
Application number: EP18165480.7A
Authority: EP
Inventors: Mr. Martin REISS; Mr. Roberto DIDONE'; Mr. Luigi PEZZATO; Mr. Lorenzo BALDO
Original assignee: Osram GmbH; Osram SpA
Current assignee: Osram GmbH; Osram SpA
Priority date: 2017-04-11
Filing date: 2018-04-03
Publication date: 2020-12-16
Anticipated expiration: 2038-04-03
Also published as: EP3388742A8; EP3388742A1

Description

Technical Field

The present description refers to methods for the production of housings for lighting devices.
One or more embodiments may refer to lighting devices employing solid-state light radiation sources, e.g. LED sources.

Technological Background

On the market there are currently available lighting devices implemented in the form of flexible linear modules. Such devices are also available in "protected" form, with a flexible light radiation source unit embedded in a flexible housing which may include, for example, polymeric materials. The housing protects the light radiation source unit from the external environment and has a limited impact on the light emission performance.
An emerging trend in the sector involves the implementation of lighting devices provided with housings having different optical functions, e.g. adapted to provide a diffused lighting or to change the color of the light radiation.
A solution which may be selected in order to implement housings for lighting devices having different optical functions may envisage the production of the housing by means of a three-component co-extrusion. For example, a process may involve the co-extrusion of:

a first layer including a transparent polymeric material,
a second layer including a diffusive or colored polymeric material,
side walls of an opaque reflecting material.

A drawback of said solution is that a three-component co-extrusion process may very costly and may involve a considerable waste of material, while being unsuitable for small production volumes.
US2010/220469 A1 discloses a LED-based replacement light for a fluorescent lighting device, comprising an extruded tubular housing having a D-shaped cross section. A light diffracting film is applied to the exterior of the tubular housing.
EP 3 045 800 A1 discloses a lighting device with a multi component housing formed by co-extrusion comprising the features of the preamble of claim 4.
DE 10 2012 218 786 B3 discloses a method to manufacture a lighting device with a pre-manufactured wall structure attached to a carrier having LED packages, the wall structure comprising openings, which are filled with filler material.
EP 2 454 520 A1 discloses a flexible light strip comprising a housing formed by co-extrusion.

Object and Summary

One or more embodiments aim at providing solutions for achieving the results described in the foregoing, so as to overcome the previously outlined drawbacks.
According to one or more embodiments, said object is achieved thanks to a method having the features specifically set forth in claim 1 that follows.
One or more embodiments may also refer to a corresponding lighting device as defined in claim 4.
The claims are an integral part of the technical teaching provided herein with reference to the embodiments.
One or more embodiments enable achieving one or more of the following advantages:

easy modification of one or more optical characteristics of the optical functional layer,
a smooth surface of the optical functional layer, without extrusion marks,
a consistent quality of the surface of the optical functional layer, while the surface of extruded components may vary according to the condition of the extrusion tools,
the method may be applied both to small-scale and to big-volume production,
the method does not require large production volumes in order to be cost-effective,
the method may enable the production of special products without high additional costs for small-scale production,
possibility of an individual adjustment of the optical functional layer to various types of LEDs,
the optical functional layer may be subjected to a reduced thermal impact because it is not directly placed on the LED surface; therefore, it is possible to use more sensitive colored pigments.

Brief Description of the Figures

One or more embodiments will now be described, by way of non-limiting example only, with reference to the annexed Figures, wherein:

Figures 1 to 3 are schematic cross-section views showing the production sequence of a housing for a lighting device, and
Figures 4-7 are schematic cross-section views showing the production sequence of a lighting device.

It will be appreciated that, for better clarity of illustration, the parts visible in the Figures are not to be considered necessarily as drawn to scale.

Detailed Description

In the following description, various specific details are given to provide a thorough understanding of examples of one or more embodiments. The embodiments may be practiced without one or several specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials or operations are not shown or described in detail in order to avoid obscuring various aspects of the embodiments. Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the possible appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments, and/or may be associated to the embodiments in a fashion other than shown herein, so that e.g. a feature exemplified herein with reference to a Figure may be applied to one or more embodiments exemplified in a different Figure.
The headings provided herein are for convenience only, and therefore do not interpret the extent of protection or scope of the embodiments.
In Figures 6 and 7, reference 10 denotes a lighting device adapted to be implemented, in one or more embodiments, as an elongated module (e.g. a rod or a ribbon), which may optionally be flexible and/or adapted to be cut to length according the application and usage needs.
As far as the present case is concerned, the lighting device 10 may therefore be considered as an element having indefinite length, shown in the view of Figure 7 in cross section with respect to the main extension direction thereof.
In one or more embodiments, device 10 may include a housing 12, e.g. having a channel-shaped profile. The housing 12 may include a central body 14 interposed between two flanks 16 extending lengthwise along two opposite side of the central body 14. In one or more embodiments, the housing 12 may include an optical functional layer 18, applied onto an outer surface 14a of the central body 14.
Always referring to Figures 6 and 7, in one or more embodiments lighting device 10 may include a light radiation source unit 20. In one or more embodiments, the light radiation source unit 20 may include:

a support board 22 substantially resembling a Printed Circuit Board (PCB), and
one or more electrically-powered light radiation sources 24, arranged on the side of the support board 22 facing central body 14.

In one or more embodiments, the light radiation sources 24 may be solid-state light radiation sources, such as e.g. LED light radiation sources.
In one or more embodiments, the light radiation source unit 20 may include a U-shaped profile 26 made of a polymeric material, e.g. white silicone, containing the support board 22. In one or more embodiments, the light radiation source unit 20 may include a potting 28 of a polymeric material, e.g. while silicone, which may cover the support board 22 while leaving the light radiation sources 24 exposed.
In one or more embodiments, the light radiation source unit 20 may be mounted into the housing 12 with the light radiation sources 24 facing an inner surface 14b of the central body 14. In one or more embodiments, the light radiation source unit 20 may be fixed to the housing 12 by means of a transparent glue layer 30.
In one or more embodiments, the light radiation source unit 20 and the housing 12 may be implemented so as to be flexible, e.g. in an up/down direction with respect to the viewpoint of the Figures.
Figures 1 to 3 schematically show an embodiment of a method for the production of a housing 12 for a lighting device. In one or more embodiments, the method may include extruding a profile 34 of polymeric material including a central body 14 having an outer surface 14a. In one or more embodiments, the central body 14 may include a transparent or partially diffusive material (e.g. a polymeric material such as silicone).
In one or more embodiments, the extruded profile may include flanks 16, which may be made of a reflective material, e.g. a polymeric material such as silicone, the reflective properties whereof may be obtained by means of reflective particles mixed into the polymer, according to a technique well-known in extrusion processes.
In one or more embodiments, the material of the central body 14 and the material of the flanks 16 may be co-extruded simultaneously in a bi-component co-extrusion process known in itself, after which an extruded profile 34 is obtained having the cross-section shape shown in Figure 1.
In one or more embodiments, the extruded profile 34 obtained at the output of the bi-component co-extrusion process may be subjected to a step of dispensing a polymeric material, schematically shown in Figure 2, during which step a polymeric material 32 is dispensed onto the outer side 14a of central body 14.
With reference to Figure 3, the polymeric material 32 dispensed onto the outer side 14a of the central body 14 may constitute an optical functional layer 18, having the ability of changing one or more optical characteristics of the emitted light.
The assembly obtained after the step of dispensing the polymeric material 32 may then be subjected to curing.
In one or more embodiments, the optical functional layer 18 may include a diffusive material, which is adapted to implement, on its outer surface (i.e. the side of housing 12 facing outwards of device 19), a homogeneous light output distribution in the near field. The diffusive material may include a polymeric material (such as e.g. silicone), the diffusive behaviour whereof may be obtained e.g. by means of diffusive particles (e.g. including Al₂O₃) mixed into the polymer.
In one or more embodiments, the optical functional layer 18 may be a colored material, adapted to act as a color filter, by absorbing a fraction of the color spectrum of the radiation (which may be e.g. substantially white, the effect being however also achievable with a non-white radiation) emitted e.g. by sources such as LEDs 24, so as to originate a colored chromatic flux, i.e. a radiation having a color which is determined (directly or by means of a synthesis with the color of source 24) by the color of layer 18, i.e. for example by the color of the pigments mixed into the material of layer 18.
In one or more embodiments, the optical functional layer 18 may contain diffusive particles and color pigments. In one or more embodiments, the optical functional layer 18 may contain phosphor particles, in order to change the color of the emitted light. In one or more embodiments, the optical functional layer 18 may contain phosphor particles and diffusing particles.
The implementation of the optical functional layer 18 by dispensing a polymeric material 32 may enable an easy modification of the optical functions of layer 18, by using different particles and by leaving the extruded base profile 34 unchanged. In one or more embodiments, it is thus possible to simplify the extrusion process, by reducing the number of materials to be co-extruded. In one or more embodiments, the formation of the optical functional layer by means of dispensing may avoid a three-component extrusion process, which may be costly, may involve a considerable waste of material and may be unsuitable for the production of small batches or special parts.
With reference to Figures 4 to 7, in one or more embodiments, after the curing step of housing 12, the light radiation source unit 20 may be fixed to the housing 12, e.g. by means of a transparent glue layer 30. The light radiation sources 24 of the light radiation source unit 20 may face the inner wall 14b of central body 14, i.e. the wall of central body 14 opposed to the optical functional substrate 18. In one or more embodiments, the layers permeable to light radiation, i.e. the central body 14 and the optical functional layer 18, transmit the light radiation, and the side flanks 16, adapted to include a light-impermeable material, e.g. a reflective material, may be useful for concentrating the light radiation emission through the layers permeable to light radiation.
One or more embodiments may therefore concern a method for the production of a housing (e.g. 12) of a lighting device (e.g. 10), including:

extruding a profile (e.g. 34) of polymeric material, including a central body (e.g. 14) transparent or partially diffusive having an outer surface (e.g. 14a), and
dispensing on said outer surface (e.g. 14a) of said extruded profile (e.g. 34) an optical functional layer (18) having the ability to change one or more optical characteristics of the emitted light.

In one or more embodiments, the profile (e.g. 34) of polymeric material may include two flanks (e.g. 16) of reflective material, located on opposite sides of said central body (e.g. 14).
In one or more embodiments, the material forming the central body (e.g. 14) and the material forming the flanks (e.g. 16) may be extruded simultaneously in a bi-component co-extrusion process.
In one or more embodiments, the optical functional layer (e.g. 18) may include a diffusive material.
In one or more embodiments, the optical functional layer (e.g. 18) includes a colored material.
One or more embodiments may concern an optical device including:

an elongated housing (e.g. 12) which may include an extruded profile (e.g. 34) of polymeric material, which may include a transparent or partially diffusive central body (e.g. 14) which may have an outer surface (e.g. 14a) and an inner surface (e.g. 14b), and
a light radiation source unit (e.g. 20) which may include at least one electrically powered light radiation source (e.g. 24) facing said central body (14), whereby the light radiation emitted by said light radiation source unit (e.g. 20) may propagate through said central body (14),

In one or more embodiments, the optical functional layer (e.g. 18) may include a diffusive material capable of forming, on said outer surface (e.g. 14a), a homogeneous distribution of output light in the near field.
In one or more embodiments, the optical functional layer (e.g. 18) may include a colored material capable of acting as color filter.
In one or more embodiments, the light radiation source unit (e.g. 20) may be fixed in the casing (e.g. 12) by means of a transparent glue layer (e.g. 30).
In one or more embodiments, at least one source of light radiation (e.g. 24) may be a LED source.
Of course, without prejudice to the basic principles, the implementation details and the embodiments may vary, even appreciably, with respect to what has been described herein by way of non-limiting example only, without departing from the extent of protection.
Said extent of protection is defined by the annexed claims.

LIST OF REFERENCE SIGNS

Lighting device	10
Housing	12
Central body	14
Outer surface	14a
Inner surface
	14b
Flanks	16
Optical functional layer	18
Light radiation source unit	20
Support board	22
Light radiation sources	24
U-shaped profile	26
Potting	28
Transparent glue layer	30
Polymeric material	32
Extruded profile	34

Claims

A method for the production of a housing (12) of a lighting device (10), comprising:
- extruding a profile (34) of polymeric material comprising a central body (14) of transparent or partially diffusive material and two flanks (16) of reflective material located on opposite sides of said central body (14), wherein the material forming the central body (14) and the material forming the flanks (16) are extruded simultaneously in a bi-component co-extrusion process, and

- dispensing on an outer surface (14a) of said extruded profile (34) an optical functional layer (18) having the ability to change one or more optical characteristics of the emitted light.
A method according to claim 1, wherein said optical functional layer (18) comprises a diffusive material.
A method according to claim 1, wherein said optical functional layer (18) comprises a colored material.
A lighting device (10), comprising:
- an elongated housing (12) comprising an extruded profile (34) of polymeric material comprising a central body (14) of transparent or partially diffusive material having an outer surface (14a) and an inner surface (14b), and two flanks (16) of reflective material located on opposite sides of said central body (14), wherein the material forming the central body (14) and the material forming the flanks (16) are extruded simultaneously in a bi-component co-extrusion process,

- a light radiation source unit (20) comprising at least one electrically powered light radiation source (24) facing said central body (14), whereby the light radiation emitted by said light radiation source unit (20) propagates through said central body (14),
characterized in that on said outer surface (14a) of said central body (14) there is applied by dispensing an optical functional layer (18) having the ability to change one or more optical characteristics of the emitted light.
A lighting device according to claim 4, wherein said optical functional layer (18) comprises a diffusive material capable of forming on said outer surface (14a) a homogeneous distribution of output light in the near field.
A lighting device according to claim 4 or claim 5, wherein said optical functional layer (18) comprises a colored material capable of acting as color filter.
A lighting according to any one of claims 4-6, wherein the light radiation source unit (20) is fixed in the casing (12) by means of a transparent glue layer (30) .
A lighting device according to any one of claims 4-7, wherein said at least one source of light radiation (24) is a LED light source.