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Title:
A PRINTED CIRCUIT BOARD, A METHOD FOR PRODUCING THE SAME AND AN ILLUMINATION DEVICE COMPRISING THE SAME
Document Type and Number:
WIPO Patent Application WO/2019/081802
Kind Code:
A1
Abstract:
An illumination device (401) comprises a printed circuit board (PCB; 402), a light source (403) assembled on center section (408) of the PCB and an optical device (404). The center section of the PCB is stamped so that the light emitting surface (409) of the light source in substantially at the rear focal point (406) of the optical device.

Inventors:
RÖYHKIÖ, Juha (Hiihtokatu 15, SALO, 24280, FI)
Application Number:
FI2018/050642
Publication Date:
May 02, 2019
Filing Date:
September 11, 2018
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
LEDIL OY (Joensuunkatu 13, SALO, 24100, FI)
International Classes:
G02B19/00; G02B7/02; H05K1/05; H05K1/18; H05K3/30
Foreign References:
US20140055991A12014-02-27
EP1376708A22004-01-02
EP2924333A12015-09-30
KR20110068362A2011-06-22
EP2700868A22014-02-26
Other References:
None
Attorney, Agent or Firm:
FINNPATENT OY (Smart Chemistry Park Raisionkaari 55, RAISIO, 21200, FI)
Download PDF:
Claims:
What is claimed is:

1 . An illumination device (301 , 401 ) for modifying light distribution, the illumination device comprising:

- printed circuit board (302, 402) comprising a peripheral section (307, 407) and a center section (308, 408),

- a light source (303, 403) assembled on a first surface (31 1 , 41 1 ) of the center section, and

- an optical device (304, 404) substantially surrounding the light source, characterized in that the center section of the printed circuit board is stamped so as light emitting surface (309, 409) of the light source is substantially at rear focal point (306, 406) of the optical device, in proviso that distance (d) in (±) y-direction of the coordinate system (399, 499) between the first surface of the central section (31 1 , 41 1 ) and first surface of the peripheral section (310, 410) is > 0.0 mm.

2. The illumination device according to claim 1 wherein the distance is 0.1 -1 mm. 3. The illumination device according to claim 1 or 2, wherein the printed circuit board is a metal core printed circuit board.

4. The illumination device according to claim 3, wherein the metal is aluminum.

5. The illumination device according to claim 3 or 4, wherein the first surface of the printed circuit board comprises a layer comprising glass fiber, epoxy resin and copper.

6. The illumination device according to any of claims 1 -5, wherein the light source is LED.

7. The illumination device according to any of claims 6, wherein the LED is a chip scale package LED. 8. A method for processing a printed circuit board, the method comprising providing a substantially planar printed circuit board comprising a peripheral section and a center section, determining a distance (d) between rear focal point of an optical device and light emitting surface of a light source in an illumination device when the light source is assembled on a first surface of the center section of the substantially planar printed circuit board, and the optical device is substantially surrounding the light source, characterized in that the method comprises stamping the center section of the substantially planar printed circuit board by a distance (d), in proviso that the distance is > 0.0 mm.

9. The method according to claim 8, wherein the distance is 0.1 -1 mm.

10. The method according to claim 9, wherein the printed circuit board is a metal core printed circuit board.

1 1 . The method according to claim 10, wherein the metal is aluminum. 12. The method according to any of claims 8-1 1 , wherein light source is LED.

13. The illumination device according to claim 12, wherein the LED is a chip scale package LED.

14. A printed circuit board obtainable by a method according to any of claims 8-12.

15. A system comprising a printed circuit board according to claim 14 and a light source.

Description:
A printed circuit board, a method for producing the same and an illumination device comprising the same

Field of the disclosure The disclosure relates generally to illumination engineering. More particularly, the disclosure relates to a printed circuit board and a method for producing the printed circuit board. The disclosure relates also to an illumination device comprising a printed circuit board, a light source, and an optical device such as a lens.

Background Distribution of light produced by a light source such as a light emitting diode "LED" can be important or even critical in some applications. The distribution of light produced by the light source can be modified with optical devices such as lenses. Figure 1 shows a section view of a representative part of an exemplifying illumination device 101 according to prior art. The section shown in figure 1 is taken along a plane that is parallel with the is parallel with the xy-plane of a coordinate system 199. The illumination device comprises a printed circuit board "PCB" 102, a light source 103 assembled therein and an optical device 104 substantially surrounding the light source. The optical device 104 can be for example rotationally symmetric with respect to a geometric line parallel with the y-axis of the coordinate system 199. The light source shown in the figure 1 is a traditional LED comprising a dome section 105. The optical device is designed so that when assembled as part of the illumination device, its rear focal point is located on light emitting surface of the light source 103. The position of rear focal point of the optical device 104 is shown with an arrow 106 in figure 1 . Figure 2 illustrates a representative part of an illumination device 201 comprising a printed circuit board 202, a light source 203 attached therein and an optical device 204 substantially surrounding the light source. The printed circuit board and the optical device is as in figure 1 , but the light source different. The size of the light source 203 is substantially smaller than the size of the light source 103. Thus, as the size of the light source is changed, the light emitting surface of the light source 203 is not at rear focal point of the optical device 204 when assembled as shown in the figure. The rear focal point of the optical device 204 is shown with an arrow 206 in figure 2. Thus, the rear focal point of the optical device is off by a distance (d 0 ff) from the optimal position. As the light source is not located optimally in respect to the optical device, optical performance of the illumination device is worsened. Accordingly, to allow the use of light sources of varied sizes, new design of the optical device is required. This, in turn is time consuming and expensive.

Summary The following presents a simplified summary in order to provide a basic understanding of some aspects of various invention embodiments. The summary is not an extensive overview of the invention. It is neither intended to identify key or critical elements of the invention nor to delineate the scope of the invention. The following summary merely presents some concepts of the invention in a simplified form as a prelude to a more detailed description of exemplifying embodiments of the invention.

In accordance with the invention, there is provided a new illumination device for modifying distribution of light produced by a light source.

An illumination device according to the invention comprises:

- printed circuit board comprising a peripheral section and a center section,

- a light source assembled on a first surface of the center section, and

- an optical device substantially surrounding the light source.

The center section of the printed circuit board is stamped so as light emitting surface of the light source is substantially at rear focal point of the optical device in proviso that distance (d) between the first surface of the central section and first surface of the peripheral section is > 0.0 mm.

The light source may comprise, for example, one or more light emitting diodes "LED". A preferable optical device is a lens. In accordance with the invention, there is provided also a new method for processing a printed circuit board, the method comprising, providing a substantially planar printed circuit board comprising a peripheral section and a center section, - determining a distance (d) between rear focal point of an optical device and light emitting surface of a light source in an illumination device when the light source is assembled on a first surface of the center section of the substantially planar printed circuit board, and the optical device is substantially surrounding the light source, and - stamping the center section of the printed circuit board by the distance (d), from a first surface of the peripheral section, in proviso that the distance is > 0.0 mm.

In accordance with the invention, there is provided also a stamped printed circuit board obtainable by the method of the present invention. In accordance with the invention, there is provided also a system comprising a stamped printed circuit board obtainable by the method of the present invention and a light source.

Exemplifying and non-limiting embodiments of the invention are described in accompanied dependent claims. Various exemplifying and non-limiting embodiments of the invention both as to constructions and to methods of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific exemplifying embodiments when read in conjunction with the accompanying drawings. The verbs "to comprise" and "to include" are used in this document as open limitations that neither exclude nor require the existence of also unrecited features. The features recited in dependent claims are mutually freely combinable unless otherwise explicitly stated. Furthermore, it is to be understood that the use of "a" or "an", i.e. a singular form, throughout this document does not exclude a plurality.

Brief description of the figures

The exemplifying and non-limiting embodiments of the invention and their advantages are explained in greater detail below with reference to the accompanying drawings, in which: figure 1 and 2 illustrate illuminating devices according to the prior art for modifying light distribution, figures 3 and 4 illustrate illuminating devices according to exemplifying and non- limiting embodiments of the invention, figure 5 illustrates a method for the manufacture of a printed circuit board according to an exemplifying and non-limiting embodiment of the invention, figure 6 illustrates an exemplary stamped printed circuit board obtainable by the method shown in figure 5, and figure 7 illustrates a top view of an exemplary printed circuit board according to an exemplifying and non-limiting embodiment of the invention.

Figures 1 and 2 have already been explained in the Background-section of this document.

Description of exemplifying and non-limiting embodiments The specific examples provided in the description given below should not be construed as limiting the scope and/or the applicability of the appended claims. Lists and groups of examples provided in the description given below are not exhaustive unless otherwise explicitly stated.

Figure 3 shows a section view of a representative part of an illumination device 301 according to an exemplifying and non-limiting embodiment of the invention for modifying the distribution of light emitted by a light source 303. The section shown in figure 3 is taken along a plane that is parallel with the is parallel with the xy-plane of a coordinate system 399. The illumination device comprises a printed circuit board 302, a light source 303, and an optical device 304.

The printed circuit board of the illumination device shown in the figure comprises a peripheral section 307 and a center section 308. The light source 303 is assembled on first surface 31 1 of the center section. The illumination device comprises also an optical device 304 substantially surrounding the light source. The light source and the optical device are assembled in respect each other in the illumination device preferably so that the section line A-A divides the light source and the optical device in equal portion as seen in the section view of figure 3. The center section of the PCB is stamped so as the light emitting surface 309 of the light source is substantially at the rear focal point 306 of the optical device. According to an exemplary embodiment the stamping depth, i.e. the distance (d) between first surface of the peripheral section 310 and the first surface of the center section 31 1 is 0.5 mm. According to a preferable embodiment the printed circuit board is a metal core printed circuit board (MPCB), and the core metal is preferably aluminum. Top surface of the MPCB comprises preferably a layer comprising glass fiber, epoxy resin and copper.

The light source is preferably light emitting diode "LED". A particular LED is chip scale package (CSP) LED which is typically substantially smaller than traditional LEDs. An exemplary difference is 0.5 mm in height.

The illuminating device according to the present invention may include two or more light sources such as LEDs, in particular CSP LEDs, and one or more optical devices such as lenses. An optical device may surround plurality of light sources, in particular LEDs and CSP LEDs.

A section view of an exemplary illumination device 401 comprising a stamped PCB 402 is shown in figure 4. The section shown in the figure is taken along a plane that is parallel with the is parallel with the xy-plane of a coordinate system 499. A part of the illumination device is enlarged for clarity. One of the center sections is marked with reference number 408. Accordingly, the center section of the PCB is stamped in such a way that the light emitting surface 409 of the light source 403 is substantially at the rear focal point of the lens 404. The rear focal point of the lens is marked with an arrow 406 in the enlarged part of the figure 4. Although the center sections shown herein are identical, it should be understood that a PCB and thus also an illuminating device of the present invention may include plurality of center sections wherein one of more of them has different size and/or different stamping depth.

According to another embodiment the present invention concerns a method for producing a stamped PCB. The method shown in figure 5, comprises the following actions: action 501 : provide a substantially planar printed circuit board comprising a peripheral section and a center section, action 502: determine a distance (d) between rear focal point of an optical device and light emitting surface of a light source in an illumination device when the light source is assembled on a first surface of the center section of the substantially planar printed circuit board, and the optical device is substantially surrounding the light source, action 503: stamp the center section of the printed circuit board by a distance (d). The term "substantially planar PCB" should be understood that there is no distance (d) in (±) y-direction of the coordinate system 699 between the center section 608 and peripheral section 607 of the PCB prior to stamping process.

The printed circuit board used in the method is preferably a metal core printed circuit board (MPCB). The core metal is preferably aluminum. Top surface of MPCB the printed circuit board comprises a layer comprising glass fiber, epoxy resin and copper.

When the distance (d) has been determined, the PCB is placed into a stamping press. The stamping is performed so that the distance of the first surface of the center section from the first surface of the peripheral section in the stamped PCB equals to the distance (d) towards to the predetermined rear focal point of the optical device. Accordingly, the stamping of the center section is in (±) y-direction of the coordinate system 699. According to an exemplary embodiment the stamping is in (+)-y-direction of the coordinate system 699. The stamping depth, i.e. the distance (d) may be as required by the optical device used. According to one embodiment distance is 0.1 mm - 1 mm. An exemplary distance is 0.25 mm. Another exemplary distance is 0.5 mm. Still another exemplary distance is 0.75 mm. Still another exemplary distance is 1 .0 mm.

According to another embodiment the present invention concerns a PCB obtainable by the method disclosed above. A section view of an exemplary PCB 602 obtainable by the method is shown in figure 5. The section plane is parallel with the xy-plane of a coordinate system 699. Accordingly, the PCB comprises a peripheral section 607 and a center section 608. A light source is adapted to be assembled on first surface 61 1 of the center section. The distance between the first surface of the peripheral section 610 and first surface of the center section 61 1 in y-direction of the coordinate system is marked with d that is thus also the stamping depth. The arrow in the figure demonstrated the stamping direction. An exemplary distance is 0.5 mm. Another exemplary distance is 0.75 mm. Stamping into opposite direction is also possible. This may be useful in a situation when rear focal point of an optical device would be too close to a light source in an illumination device if a substantially planar PCB were used.

Figure 7 illustrates a top view of an exemplary printed circuit board 702 according to the present invention. One of the stamped center portions is marked with reference number 708, and the peripheral section is marked with reference number 707 According this embodiment the stamped part of the PCB is square, and the PCB is designed for light sources. It is obvious for a skilled person that different design options are available.

The specific examples provided in the description given above should not be construed as limiting the scope and/or the applicability of the appended claims. Lists and groups of examples provided in the description given above are not exhaustive unless otherwise explicitly stated.