Lighting device with semiconductor light source

Abstract

Lighting device (1) comprising at least one semiconductor light source (4), wherein - the semiconductor light source (4) is laterally surrounded by a light-transmitting ring-shaped TIR body (8; 18, 19; 28, 29), - the TIR body (8; 18, 19; 28, 29) has an outer surface (10) facing away from at least one semiconductor light source (4) with a TIR structure (11) and - the TIR structure (11) is designed to reflect light (L) incident on its interior through a light exit aperture (13) of the TIR body (8; 18, 19; 28, 29), and - the TIR body has a hollow cylindrical basic shape, with the TIR structure being formed on its outer surface.

Description

[0001] The invention relates to a lighting device with at least one semiconductor light source. The invention is applicable, for example, to retrofit lamps or modules, particularly for spotlights with wide beam angles, especially with at least one LED as the semiconductor light source.

[0002] LED retrofit lamps are available to replace conventional MR16 halogen lamps, typically offered with nominal beam angles of 24 degrees, 36 degrees, or even 120 degrees (full angle). These lamps with different nominal beam angles are generally manufactured from identical components, differing only in the beam-expanding optical element. While lenses are often used to adjust the beam angle for nominal beam angles of less than 120 degrees, for large nominal beam angles of approximately 120 degrees, the light emitted by the LED is used without any primary beam shaping.

[0003] The LED often emits light at angles even larger than its nominal beam angle, for example, if the LED's radiation pattern is at least approximately similar to that of a Lambertian radiator. However, since the same housing is used for both large and small nominal beam angles, light emitted by the LED at very wide angles (e.g., between 160 and 180 degrees) is blocked by the housing of the LED retrofit lamp. This leads to a decrease in the efficiency of the LED retrofit lamp.

[0004] To increase efficiency, a reflector can be used to reflect the light incident on the housing for use as usable light. A disadvantage of this approach is that the reflector is either an additional component or a coating on the housing, thus requiring an additional manufacturing step. Furthermore, reflective coatings are susceptible to chemical corrosion and, especially on plastic substrates, are often prone to coating delamination. Therefore, reflector-based solutions are disadvantageous from a cost, manufacturing, and durability perspective.

[0005] There are lamps known in which a curved cover is provided as an alternative to a reflector, but this does not significantly reduce the amount of light blocked by the housing.

[0006] Patent application US 2012 / 0240976A1 describes a luminaire assembly with a transparent housing, wherein the transparent housing has an inner chamber that gradually widens from bottom to top, with a faceted inner wall and a totally reflective outer wall. Patent applications DE 102011002483A1, DE 202011051168U1, and DE 102012223860A1 each describe an optical unit of a retrofit lamp in the form of a spotlight with optical elements, such as TIR lenses, Fresnel lenses, and reflectors, for generating directional radiation. Patent application DE 102010016385A1 describes a lighting arrangement with light-emitting diodes, wherein each light-emitting diode is associated with a glare-reducing element with a cylindrical recess. The publication DE 10 2013 220 218 A1 describes a luminaire with a TIR reflector arrangement with two nested shell-shaped reflector rings.Patent applications US 2007 / 0133209A1, US 5173810A, and CN 101858548A each describe an LED lamp with a TIR lens, the TIR lens having a substantially parabolic outer profile for shaping a directional beam. Patent application US 2012 / 0063146A1 describes a light source with Fresnel optics, and patent application DE 102004024599A1 describes a light source with a translucent housing in which total internal reflection can occur.

[0007] The object of the present invention is to overcome at least some of the disadvantages of the prior art and, in particular, to provide a more cost-effective way of increasing the luminous efficacy of a semiconductor lighting device, especially an LED lamp, using simpler manufacturing methods, which can also be designed to be stable over the long term.

[0008] This problem is solved according to the features of the independent claims. Preferred embodiments can be found in particular in the dependent claims.

[0009] The problem is solved by a lighting device in which the semiconductor light source is laterally surrounded by a translucent, ring-shaped TIR body. The TIR body has an outer surface facing away from the at least one semiconductor light source, featuring a TIR structure, and this TIR structure is configured to reflect light incident on its interior through a light-emitting aperture of the TIR body. The lighting device can therefore, in particular, have at least one semiconductor light source that is laterally surrounded by a translucent, ring-shaped TIR body, the outer surface of which, facing away from the at least one semiconductor light source, has a TIR structure for reflecting light incident on its interior. The light can thus exit through a light-emitting aperture of the TIR body. In particular, an inner surface of the TIR body can face the at least one semiconductor light source.

[0010] This lighting device offers the advantage that the light emitted by the at least one semiconductor light source at sharp lateral beam angles no longer falls onto the housing, but is reflected by the TIR body (possibly multiple times) and then exits – typically through the light-emitting aperture. Since the reflected light is no longer absorbed, it can be used as usable light, thus increasing luminous efficacy. Furthermore, such a TIR body does not require a reflective coating, which increases its lifespan. In addition, eliminating the need for a light-reflecting coating saves on complex manufacturing steps.

[0011] The lighting device can have a housing to which at least one semiconductor light source and, if applicable, the TIR body are arranged or attached. The housing can be made at least partially of plastic.

[0012] Light emitted from the at least one semiconductor light source can either be directed straight onto the light exit aperture (i.e., without striking the TIR structure) if the beam angle is small, or it can enter the annular TIR body through its inner surface and then strike the structure from the inside. At the TIR structure, the light is reflected back through the body by total internal reflection and then exits the body from the inside. Since the light from the semiconductor light source is emitted only into a front or upper hemisphere, with each reflection it is directed further towards the light exit aperture, from which it emerges after one or more reflections.Therefore, a "virtual" light emission surface is created at the light exit aperture of the TIR body, which is elevated compared to the at least one semiconductor light source and thus no longer hits the housing even under a strong lateral light emission angle, but shines over it.

[0013] Preferably, the at least one semiconductor light source comprises at least one light-emitting diode (LED). If multiple LEDs are present, they can emit the same color or different colors. A color can be monochromatic (e.g., red, green, blue, etc.) or multichromatic (e.g., white). The light emitted by the at least one LED can also be infrared light (IR LED) or ultraviolet light (UV LED). Multiple LEDs can produce a mixed light, e.g., a white mixed light. The at least one LED can contain at least one wavelength-converting phosphor (conversion LED). The phosphor can be arranged remotely from the LED, either as an alternative or additional component ("remote phosphor"). The at least one LED can be in the form of at least one individually packaged LED or at least one LED chip. Multiple LED chips can be mounted on a common substrate ("submount").The at least one light-emitting diode (LED) can be equipped with at least one dedicated and / or shared optical system for beam guidance, e.g., at least one Fresnel lens, collimator, and so on. Instead of or in addition to inorganic LEDs, e.g., based on InGaN or AlInGaP, organic LEDs (OLEDs, e.g., polymer OLEDs) can also be used. Alternatively, the at least one semiconductor light source can, for example, include at least one diode laser. A wavelength-converting phosphor may also be connected downstream of the at least one diode laser, e.g., in a LARP (Laser Activated Remote Phosphor) arrangement.

[0014] The at least one semiconductor light source can be exactly one semiconductor light source, in particular exactly one LED.

[0015] The ring-shaped TIR body has a ring-shaped basic form, which in top view (for example along a longitudinal axis or axis of symmetry) can be oval, ring-shaped or angular (e.g. triangular, rectangular, hexagonal, etc.).

[0016] The ring-shaped TIR body can, in particular, have a hollow cylindrical shape. The ring-shaped TIR body exhibits the TIR structure, especially on its outer surface. The light exit aperture is bounded or defined by an upper edge of the TIR body and can, in particular, correspond to an upper surface of the ring-shaped TIR body.

[0017] The at least one semiconductor light source is located in the region of a lower surface of the annular TIR body. It may, for example, partially project into the annular TIR body or be entirely contained within it. The lower surface may be bounded or formed by the lower edge of the TIR body.

[0018] The lighting device can be attached, in particular, to its rear or back section and may, for example, have a base (e.g., an Edison socket or a bipin socket) at a rear end. The lighting device emits its light primarily forward or upward, for example, into a front or upper hemisphere. The terms "rear" or "bottom" and "front" or "top" can be used analogously in this context. In particular, a longitudinal axis of the lighting device may extend from back to front and may coincide with a main direction of emission from the lighting device.

[0019] It is a further development that a lower edge of the TIR body corresponds to a support edge or a base of the TIR body. This allows the TIR body to rest on the same surface of the lighting device, e.g., a housing of the lighting device, as the at least one semiconductor light source.

[0020] The ring-shaped TIR body can be open on both surfaces, open on one surface and closed on the other, or closed on both surfaces.

[0021] The TIR body is particularly transparent. This translucent TIR body can be made of materials such as plastic (e.g., PP, PMMA, ABS, PC, etc.) or glass. Glass offers exceptionally high resistance to aging and a particularly high refractive index. Plastic is especially inexpensive and lightweight.

[0022] It is a further development that the at least one semiconductor light source is arranged centrally to the TIR body, in particular on a longitudinal axis of the TIR body. This has the advantage that the light rays emitted by the at least one semiconductor light source illuminate the TIR structure uniformly all around, thus easily preventing, for example, the situation where the incident light rays no longer meet the conditions for total internal reflection in some areas of the TIR structure.

[0023] One embodiment of the lighting device comprises a bowl-shaped area with a base and a rim, with at least one semiconductor light source arranged on the base and the TIR body positioned between the at least one semiconductor light source and the rim. This allows for a particularly simple design. The bowl-shaped area corresponds, in particular, to a front area of ​​the housing.

[0024] It is a further development that the bowl-shaped area is part of the housing of the lighting device. It is a further development that at least the bowl-shaped area is made of plastic.

[0025] It is a further step to understand that the ground surface is a flat or level ground surface.

[0026] It is also a further development that the edge of the bowl-shaped area is a ring-shaped, in particular annular, edge.

[0027] To achieve a particularly high light output, the TIR body can be so tall that no light ray from the at least one semiconductor light source can pass by the TIR body and hit the housing, especially its edge.

[0028] In particular, the light-emitting surface of the TIR body is at least at the same height as the edge of the bowl-shaped area. Height can be understood, in particular, as a position along a longitudinal axis of the lighting device.

[0029] It is a further development that the ring-shaped TIR body is open on the top and bottom, i.e., it has open base surfaces.

[0030] In another embodiment, the ring-shaped TIR body has at least one practically non-reflective or imperceptibly reflective covering area that covers a respective base surface. This covering area can also provide additional protection for, for example, the at least one semiconductor light source.

[0031] It is a further development that the at least one covering area has a (flat or curved) plate-like basic shape. The covering area can therefore assume the function of a covering element, in particular for the at least one semiconductor light source.

[0032] It is a further development that at least one covering area is manufactured separately from the ring-shaped TIR body or from the ring-shaped area of ​​the TIR body and subsequently connected to it.

[0033] It is a particularly cost-effective and robust further development that the at least one covering area is manufactured in one piece together with its annular TIR area of ​​the TIR body (i.e., not manufactured separately). The TIR body equipped with the at least one covering area can, for example, be manufactured as an injection-molded part.

[0034] The covering area can be transparent or diffusely reflective. If it is diffusely reflective, it can be manufactured, for example, as a single piece with the ring-shaped TIR body using a two-component injection molding process.

[0035] In another embodiment, a covering area is curved from an edge – particularly a bottom edge – of the annular TIR area of ​​the TIR body into an interior space of the annular TIR area. Such a covering area can act as a compact, dome-like cover.

[0036] It is a further development that the covering area closely adjoins the annular TIR region of the TIR body, as this allows for particularly effective protection of the at least one semiconductor light source. The covering area can completely enclose the at least one semiconductor light source.

[0037] Another design feature is that the TIR body has a translucent cover plate as a covering area, which covers the light exit aperture.

[0038] This is a further development of the principle that the cover area tightly seals the light-emitting aperture, thus enabling particularly effective protection of the at least one semiconductor light source. The cover plate can be attached to the upper edge of the annular TIR area. It can be flat or curved.

[0039] It is also possible to design the cover plate by spacing it away from the light-emitting aperture, for example, using thin spacers. This has the advantage that light cannot directly enter the cover plate from the annular region of the TIR body. The cover plate is thus separated from the annular region, particularly by a gap, and mechanically connected to it only by local spacers (e.g., three or four spacers). Such a spacer can be manufactured in one piece, for example, as an injection-molded part.

[0040] The cover plate can also serve as a cover plate for the housing, e.g., for the shell-shaped area of ​​the housing. This saves on components and simplifies manufacturing.

[0041] Furthermore, one embodiment of the TIR structure features V-shaped longitudinal grooves that are adjacent to one another in the circumferential direction and aligned parallel to each other in the longitudinal direction. Such a TIR structure is easy to manufacture and can reflect incident light rays virtually without loss and very uniformly in the circumferential direction. The longitudinal grooves are therefore aligned parallel to, or at least approximately aligned with, the longitudinal axis.

[0042] It is also possible for the ring-shaped TIR body to have a basic shape that widens, particularly from bottom to top. This allows the maximum beam angle of the light beam emitted from the light-emitting surface to be reduced. Furthermore, this reduces the number of reflections required at the TIR structure for emission, which is particularly advantageous for light beams emitted almost horizontally.

[0043] The TIR structure can be straight or curved in a cross-sectional view through the ring-shaped TIR body. It can be aligned parallel or obliquely with respect to a longitudinal axis of the TIR body.

[0044] It is a further development that the lighting device is a lighting module.

[0045] It is a further development that the lighting device is a "Light Engine", i.e. a combination of at least one light module with operating electronics, which may, for example, include a driver for the at least one semiconductor light source.

[0046] It is also a further development that the lighting device is a lamp.

[0047] It is also possible for the lighting device to be a replacement or retrofit lamp. This can be used as a replacement for conventional lamps. For example, it may have a base that fits into standard lamp sockets and is therefore designed analogously to conventional bases.

[0048] It is important to understand that a retrofit lamp is a retrofit incandescent lamp and is therefore designed to replace conventional incandescent bulbs. For this purpose, the retrofit incandescent bulb can have, for example, an Edison screw base or a bayonet base.

[0049] Furthermore, it is a design feature that the retrofit lamp is configured to illuminate a localized area and, for example, does not produce isotropic light emission. In particular, the retrofit lamp can have a large (nominal) beam angle, which can be, for example, in a range between 90° and 140°, especially around 120°. Such a lamp can be referred to as a "spot lamp" without general limitation. Such a retrofit lamp can, for example, serve as a replacement for a halogen lamp, especially of the MR type, e.g., type MR16.

[0050] It is a further development that the retrofit lamp is designed as a retrofit lamp for replacing lamps that are suitable for use in PAR spotlights or other spotlights with wide beam angles.

[0051] The properties, features, and advantages of this invention described above, as well as the manner in which they are achieved, will become clearer and more readily understandable in connection with the following schematic description of exemplary embodiments, which are explained in more detail in conjunction with the drawings. For clarity, identical or equivalent elements may be designated with the same reference numerals. Fig. Figure 1 shows a sketch of a retrofit lamp as a sectional view in side view; Fig. Figure 2 shows a section of the retrofit lamp in a view from a slightly angled top view. Fig. 1; Fig. Figure 3 shows a view from a slightly angled top view of a Fig. 2 analogous section from a retrofit lamp according to a first embodiment with a TIR body; Fig. Figure 4 shows a top view of a section of the TIR body. Fig. 3 with a path of a possible light ray; Fig. Figure 5 shows a sectional view in side view of another TIR body in relation to an LED; and Fig. Figure 6 shows another TIR body in a cross-sectional view from a slant above.

[0052] Fig. Figure 1 shows a sketch of a lighting device serving as a lamp, for example in the form of an MR16 LED retrofit lamp 101, as a sectional view in side view.

[0053] The lamp 101 has a base 3, e.g., in the form of a GU5.3 pin base, at a rear end region of a housing 2 with respect to a longitudinal axis S. A semiconductor light source, e.g., an LED 4 emitting white light, is arranged at the front and thus in the direction of the longitudinal axis S, specifically centrally and thus on the longitudinal axis S.

[0054] As also in relation to section A more precisely in Fig. As shown in Figure 2, the housing 2 is designed on the front as an open, bowl-shaped area 5. The bowl-shaped area 5 has a flat, circular base 6, which is surrounded on all sides by an upright, annular rim 7. The LED 4 is positioned centrally on the base 6 and has a main emission direction or optical axis z that coincides with the longitudinal axis S. The rim 7 can be used, for example, to hold a reflector in lamps with narrow nominal beam angles. The rim 7 can also serve to hold a translucent cover such as a lens or bulb.

[0055] Referring again to Fig. At smaller beam angles (relative to the longitudinal axis S), the light L emitted by the LED 4 is emitted directly from the bowl-shaped area 5 without striking the edge 7. At larger beam angles, however, the light L emitted by the LED 4 strikes the edge 7 and would be blocked and noticeably absorbed there without further measures.

[0056] Fig. 3 shows one to Fig. Figure 2 shows an analogous section of an MR16 LED retrofit lamp 1. Lamp 1 is similar in construction to lamp 101, but now additionally features an annular TIR body 8 that surrounds the LED 4 laterally (i.e., in an (x,y) plane of the LED 4). The TIR body 8 is positioned between the LED 4 and the edge 7, such that it prevents a direct line of sight from the LED 4 to the edge 7. The TIR body 8 is made of transparent plastic (e.g., PC or PMMA) or transparent glass. The LED 4 is positioned centrally with respect to the TIR body 8, such that the center point of the TIR body 8 lies on the longitudinal axis S.

[0057] An inner surface 9 of the TIR body 8 faces the LED 4 and is unstructured, although it may be microscopically roughened to improve the coupling in and / or coupling out of the light L. The outer surface 10 facing away from the LED 4 has a TIR structure 11. The TIR structure 11 has V-shaped longitudinal grooves 12 that are adjacent to each other in their circumferential direction and parallel to each other in the longitudinal direction (i.e., in the orientation of the longitudinal axis S).

[0058] The LED 4 protrudes into an open lower cover surface 14 of the TIR body 8 or is located entirely within the area of ​​the lower cover surface 14 of the TIR body 8. The TIR body 8 can rest on the base surface 6 with its lower edge, which spans the lower cover surface 14, and can be attached there, for example.

[0059] As in Fig. Figure 4 shows a top view of a section of the TIR body 8. Light L incident on the inner surface 9 is coupled into the TIR body 8 and travels towards the TIR structure 11 of the outer surface 10. The surfaces of the V-shaped longitudinal grooves 12 are angled such that the incident light L is reflected twice due to total internal reflection, before traveling back to the inner surface 9 and being coupled out again. Since the light L emitted by the LED 4 onto the TIR body 8 is directed obliquely forward, it can consequently "rise" within the TIR body 8 by TIR reflection until it reaches an open upper surface serving as a light exit aperture 13. The light L is therefore no longer absorbed at the edge 7 (because it no longer reaches the edge 7) but can be used as usable light, which significantly increases the luminous efficacy.For example, the radius of the TIR body 8, the opening angle of the v-shaped longitudinal grooves 12 and their height can be adjusted as required.

[0060] Fig. Figure 5 shows a further TIR body 18 in a sectional view in side view with respect to a position of the LED 4.

[0061] The TIR body 18 can, for example, be used with lamp 1 instead of the TIR body 8.

[0062] The TIR body 18 has a transparent annular TIR region 19, which is shaped similarly to the TIR body 8, but is now slightly straightened from bottom to top (i.e. along a direction of the longitudinal axis S), which facilitates light emission through its light emission aperture 13.

[0063] The TIR area 19 can rest with its lower edge 20 on the base surface 6 or – e.g., for improved ventilation and thus improved heat dissipation from the area of ​​the LED 4 – have a gap 21 to the base surface 6. Light emission through the gap 21 is negligible, since the emission surface of the LED 4 can be higher and, moreover, light emission from the LED 4 perpendicular to the optical axis z is practically negligible.

[0064] The front or top light-emitting surface 13 is covered by an upper, translucent (transparent or translucent) and practically non-reflective cover plate 22, which can also cover the entire open front of the bowl-shaped area 5. For this purpose, the cover plate 22 can, for example, rest on the edge 7 at its front. The flat cover plate 22 is spaced from the light-emitting surface 13 by a gap 23. The cover plate 22 is manufactured in one piece or integrally (e.g., using the same mold) from plastic with the TIR area 19, with the mechanical connection of these two sub-areas 19 and 22 of the TIR body 18 being achieved by small integral spacers 24. This improves air circulation to the LED 4 and suppresses unwanted light transmission from the TIR area 19 to the cover plate 22. However, the cover plate can also be connected directly to the TIR area 19.

[0065] Fig. Figure 6 shows a further TIR body 28 in a sectional view from an oblique angle above. The TIR body 28 can, for example, be used instead of the TIR body 8 with the lamp 1.

[0066] The TIR body 28 has a transparent ring-shaped TIR region 29, which may be shaped similarly to the TIR body 8 or the TIR region 19.

[0067] Starting from the lower or bottom edge 20 of the TIR area 29, a translucent (especially transparent) cover area 30 can extend inwards, which – e.g., in a spherical shape – is curved into an interior of the TIR body 28. The cover area 30 protects the LED 4, and in one variant, ventilation of the LED 4 is possible by spacing the bottom edge 20 from the base surface 6.

[0068] Although the invention has been illustrated and described in detail by the exemplary embodiments shown, the invention is not limited thereto and other variations can be derived by a person skilled in the art without leaving the scope of protection of the invention.

[0069] In general, “ein”, “eine”, etc. can be understood to mean singular or plural, especially in the sense of “at least one” or “one or more”, etc., unless this is explicitly excluded, e.g. by the expression “exactly one”, etc.

[0070] A numerical specification can also include exactly the specified number as well as a normal tolerance range, unless this is explicitly excluded. Reference sign 1 lamp 2 cases 3 sockets 4 LED 5 Bowl-shaped area 6 floor area 7 Rand 8 TIR bodies 9 Inside of the TIR body 10 Outer surface of the TIR body 11 TIR structure 12 longitudinal groove 13 Light exit aperture 14 Lower surface of the TIR body 18 TIR bodies 19 Ring-shaped TIR region 20 Lower edge of the TIR body 21 column 22 Cover plate 23 gap 24 spacers 28 TIR bodies 29 TIR area 30 Coverage area 101 Lamp A section L light S Longitudinal axis x Body-fixed axis of the LED y Body-fixed axis of the LED z Optical axis

Claims

Lighting device (1) comprising at least one semiconductor light source (4), wherein: - the semiconductor light source (4) is laterally surrounded by a translucent ring-shaped TIR body (8; 18, 19; 28, 29), - the TIR body (8; 18, 19; 28, 29) has an outer surface (10) facing away from the at least one semiconductor light source (4) with a TIR structure (11), and - the TIR structure (11) is configured to reflect light (L) incident on the inside through a light exit aperture (13) of the TIR body (8; 18, 19; 28, 29), and - the TIR body has a hollow cylindrical basic shape, wherein the TIR structure is formed on its outer surface. Lighting device (1) according to claim 1, wherein - the lighting device (1) has a bowl-shaped area (5) with a base surface (6) and an edge (7), - the at least one semiconductor light source (4) is arranged on the base surface (6) and - the annular TIR body (8; 18, 19; 28, 29) is arranged between the at least one semiconductor light source (4) and the edge (7). Lighting device (1) according to one of the preceding claims, wherein the annular TIR body (8; 18, 19; 28, 29) has at least one non-reflective covering area (22; 30) that covers a respective base area (13, 14). Lighting device (1) according to claim 3, wherein a covering area (30) extends from a bottom edge (20) of the TIR body (28, 29) into an interior of the TIR body (28, 29). Lighting device (1) according to one of claims 3 or 4, wherein the TIR body (18, 19) has a light-transmitting cover plate (22) as a cover area which covers the light emission opening (13). Lighting device (1) according to claim 5, wherein the cover plate (22) is spaced apart from the light emission opening (13). Lighting device (1) according to one of the preceding claims, wherein at least the bowl-shaped area (5) is made of plastic. Lighting device (1) according to one of the preceding claims, wherein the TIR structure (11) has v-shaped longitudinal grooves (12) that are adjacent to each other in its circumferential direction and are aligned parallel to each other in the longitudinal direction (S). Lighting device (1) according to one of the preceding claims, wherein the ring-shaped TIR body (18, 19; 28, 29) has an expanding basic shape. Lighting device (1) according to one of the preceding claims, wherein the lighting device is a retrofit lamp (1). Lighting device (1) according to claim 10, wherein the retrofit lamp has a nominal beam angle in a range between 90° and 140°.

Images