RU2761176C1 - Flat led illuminator with a large area of the light-emitting surface - Google Patents

Abstract

FIELD: lighting.

SUBSTANCE: invention relates to the field of lighting equipment and can be used for creating illumination decorative design lighting apparatuses and advertising light panels. The flat LED illuminator with an arbitrarily large area of the light-emitting surface comprises a flat light guide, a printed circuit board with two groups of LEDs mounted on bent parts of the board, placed in through holes in the light guide so that the emission thereof is directed in opposite directions, and a power source is mounted on the LED board.

EFFECT: increase in the homogeneity of the light flux created by a large light-emitting surface.

2 cl, 6 dwg

Description

Technology area

The invention relates to lighting engineering, in particular to lighting devices based on an end-illuminated light guide, which can be used for general or local lighting, as well as for creating decorative, design and advertising light panels.

Prior art

Edge lighting is now widely used, since it allows you to get absolutely uniform illumination, and the illuminator itself does not have the characteristic points inherent in LED lighting and allows you to get a very thin illuminator, which is impossible in illuminators with light-emitting diodes.

Known design of an illuminator with a body characteristic of a lamp (RF patent 2706799 (publication of international application WO2020106183) "Flat LED illuminator with a wide range of light power and internal illumination" by Sokolov Y.B.), which can be a replacement for Spot lamps having a very wide spread throughout the World. However, the design is rather complicated and does not allow obtaining a high luminous flux, which is necessary for large-format emitters due to the limited number of LEDs that fit along the length of the illuminator ring. The presence of a bulky body limits the use of such lamps.

Technical solution

When developing the illuminator, the task was to create such a structure that would be easy to manufacture, as flat as possible (low height), versatile, in the sense of being able to be embedded in a decorative ceiling, often into existing holes, had the ability to transform in terms of power, i.e. suitable for large formats of illuminators up to a square meter and more, had the ability to be built into various types of lighting surfaces of various configurations, working as suspended and surface-mounted illuminators.

The proposed device solves the problem of creating a large light-emitting surface that has a uniform glow and is able to create both a uniform luminous flux and areas with the required radiation brightness. Uniformity is understood as a given luminous efficacy from the radiation surface. A flat optical fiber is used as a medium for transmitting light radiation.

The technical result of the proposed solution is to increase the uniformity of the light flux generated on a large light-emitting surface.

To achieve the specified technical result, it is proposed to introduce light radiation through the end surface of the hole made in the form of a groove, the width and length of which is sufficient to accommodate a row of LEDs directed to the end surfaces of the said groove in the light guide. The combination of the location of the grooves makes it possible to obtain a uniform transmission of light radiation along the fiber in all directions. The output of radiation from the fiber is carried out in combination with the creation of points of optical inhomogeneity on the light-emitting surface of the fiber.

A planar illuminator with a large light-emitting surface contains a planar light guide having at least one through hole, the cylindrical surface of which configures the end surface of the hole; a printed circuit board on which the LEDs are mounted, positioned so as to illuminate the end surface of the aperture of the flat light guide, while the through holes in the flat light guide are in the form of straight slots located so that the said slots do not intersect each other, and the printed circuit board has bent straight fragments, on which the LEDs are located, while the fragments of the printed circuit board are located in the straight through grooves of the flat light guide, which are located so that they do not intersect each other.

Through slots can be configured in a group and are located like the sides of a simple N-gon, where N is a natural number chosen from the inequality N> 3. A power supply is mounted on the surface of the printed circuit board, bounded by bent fragments.

At the intersection of the direction of adjacent through grooves, a through hole can be arranged to accommodate a bent piece of a printed circuit board with the LED directed in the direction opposite to the direction of emission of the LEDs located in the straight through grooves.

Depending on the dimensions of the flat light guide, two or more LED boards can be located over its entire surface, installed in the indicated order.

The printed circuit board (1) can be made in the form of a square, inside which, on the bent U-shaped cutouts (14), the first group of LEDs (8) is located, which in turn consists of 6 subgroups arranged in the form of a hexagon. This group of LEDs is directed outwardly and parallel to the plane of the board. Between the groups of this hexagon there is a second group (13) of LEDs (9) which are directed towards the center of the hexagon. In the same hexagon in the center of the board, there is a power supply that powers all LEDs (of both groups). As a rule, this design uses the so-called sequential power supply (12), since it consists of SMT components without the use of large components installed in holes. This board is completely executed on SMT automated lines without manual labor. In fig. 2 shows a general view of the illuminator.

On the surface of the printed circuit board (1), the reverse side of the installation of electronic components, a sheet of aluminum radiator (20) covered with an insulating film (17) is installed, a fastener (16) is installed on top, and this whole structure with a light guide (5) and a diffuser (23) is compressed a single screw (21) in the center (26) of the illuminator with an emphasis on the cylindrical bushings (10, 11), put on the mounting screw after installing the light guide and diffuser on it.

Along the perimeter of the illuminator, the diffuser and the light guide with the reflector are fastened with rivets 25 and on them along the perimeter there is a white shell made of silicone, which acts as a reflector and gives the illuminator a complete structure. The assembly sequence is as follows: a reflector (23) is put on the screw (21), a light guide (5), then two bushings (10) and (11), as well as a gasket with bushings (3) on which the printed circuit board (1) is installed. Since the light guide (5) has the same cutout configuration as the bent sections of the board with LEDs (cutouts 22.1, 22.2, Fig. 3), when the printed circuit board is installed in the structure, the LEDs are exactly opposite the inner end of the fiber, while the radiation of group 1 LEDs are directed from the center of the fiber to the periphery, and the radiation of group 2 is directed to the center of the illuminator. Next, a flat sheet of aluminum is applied to the printed circuit board (1) - a radiator (20), which is an additional heat dissipator from the printed circuit board; at a low illuminator power (up to 10 W), the printed circuit board itself can dissipate heat if its area is sufficient. Since this design uses a sequential driver that is not isolated from the AC mains, it is necessary to additionally isolate the radiator (20) from contact, ensuring the safety of personnel installing the illuminator; for this, an insulating film (17) is applied to the radiator (20) (the edges of which are wrapped inward, which is not shown) providing a breakdown voltage of 4 kV. This creates a double insulation of the metal parts from the AC mains. The first insulation level is prepreg on the PCB and the second insulation level is high breakdown film (17). Further, a metal part (16) is put on the screw (21), which with the help of a nut (18 fig. 2) presses the radiator (20) to the printed circuit board (1), providing thermal contact between them. The height of the stop 3 on the spacer (3.1) is determined by the highest driver component, the lower these components, the lower the height of the sleeve (3) can be and the flatter the illuminator will be. In addition, the stop 3 provides a gap between the radiator (20) and the light guide, which contributes to better heat dissipation, since not only the outer (upper) surface of the radiator works, but also the lower one. Since the film (17) has a small thickness (40 ... 60 microns), it practically does not interfere with the radiation of heat, since the heat losses on the film are no more than 2 ... 3 degrees Celsius. Part (16) has corresponding holes that allow you to put springs for mounting in a ceiling hole or two shaped cutouts for mounting on a wall (Fig. 4). In fig. 4 shows a disassembled illuminator for the case of a circular illuminator configuration. In fact, its size and shape may vary. With high power and large dimensions, only a suspended version is possible, when the suspension is made from the holes (7 fig. 4). In general, the entire package of the illuminator is fastened along the perimeter with rivets (25) inserted into the holes (7.1 Fig. 4). In this figure, the bushing (3) is shown as a piece of square shape with a certain thickness with a shaped large hole that allows you to install a board with components. In principle, the bends in the board for LEDs can be along any polygon. The more corners, the more complex the board (more bends), the fewer angles (minimum triangle), the more likely dark spots on the diffuser near the LEDs of the first group are.

The perimeter of the illuminator can have various shapes, both symmetrical (polygon, circle, ellipse, rhombus, etc.) and asymmetrical shape with certain restrictions. In order for the illuminator to work, defects (dots, dashes, etc.) are applied to the surface of the fiber, which are actually secondary light emitters. Light from these defects exits into both planes of the fiber; if upward illumination is not required, then the entire surface of the fiber is covered with a reflective film (7).

If there is no reflector (7), then the light will go out to both sides of the fiber and its upward beams will illuminate the ceiling. The light propagates along the optical fiber and, having reached the perimeter, will leave the illuminator, therefore, a white shell is installed along the perimeter (20 fig. 4), which reflects the light back into the optical fiber and gives the illuminator a complete structure.

The design of the illuminator is universal in the sense that it can have different power and external dimensions. The higher the power, the larger the area of the printed circuit board and the aluminum heat sink must be, and, accordingly, the outer dimensions of the illuminator can be larger. Up to a diameter of 300… 350 mm, the illuminator can be installed by means of springs in the ceiling openings. For large sizes, it is advisable to mount the illuminator suspended or overhead.

Figure 5 shows the design of a printed circuit board in which the cutouts are in an octagon, this board is larger, it has more LEDs, and this design is more suitable for a large illuminator with a nominal diameter of up to 1 m or more. However, the construction is similar.

In fig. 3 shows 4 holes (24), which, as a rule, are absent and are only needed when they want to reduce the thickness of the illuminator by the thickness of the fiber sheet, as a rule, by 4 mm, then the highest components (electrolytic capacitors) enter these holes all the way with diffuser. This will create dark circles on the illuminator that will be noticeable.

Due to the side glow of the LEDs, there will be an increased glow along the contour of the n-gon of the printed circuit board, which will be visible on the diffuser. To minimize this, a paint ring can be applied to the inner surface of the diffuser to reduce the difference in illumination in the side-emitting areas of the LEDs.

On the basis of such a design, illuminators of a very large format (within the dimensions of a PC or PMMA sheet) can be built, up to 2 × 3 m with several centers of illumination. In fig. 6 shows for example an illuminator with two centers of illumination in the form of an ellipse. It should be noted that the principle of Edge lighting is based on the fact that microscopic defects are applied to the light guide using a laser or printer, which are radiation points in the illuminator. Therefore, when designing illuminators with several lighting centers, it is necessary to calculate the density of defects using special programs, otherwise the illuminator surface will not have uniform illumination over the entire surface, and this will be visually perceived as an illuminator defect. At the same time, with large sizes of the illuminator, with a correctly selected program for applying defects, this uneven illumination can be perceived as a design technique and well received by experts. Also, with large sizes of the illuminator in the presence of several centers of illumination, defects on the light guide can be applied in such a way that they will form a pattern conceived by the designer, for example, a star, circle, n-gon, etc. arbitrary patterns and all these defects, applied according to a certain law, will glow and give the impression of a luminous picture. Where there are no defects, there will be a dark area. And these will not be just luminous images, but images that illuminate the space as illuminators.

Claims (7)

1. A flat end-illuminated illuminator containing: - a flat fiber having a through hole forming the end surface of the fiber, - a printed circuit board on which LEDs are mounted, positioned so as to illuminate the end surface of the light guide; characterized in that: through holes are made in the form of grooves, LEDs are mounted on bent-out pieces of a printed circuit board, each of which is located in one of the slots of the light guide. 2. A flat illuminator with end illumination according to claim 1, characterized in that the flat light guide has N slots oriented like the sides of an N-gon, where N is a natural number selected from the inequality N> 3, while the first part of the printed circuit board fragments is configured with the possibility of illuminating the part of the light guide, limited by the grooves, and the second part of the fragments - with the possibility of illuminating the outer part of the light guide.

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