Light-emitting device

Abstract

A light-emitting device is proposed, which has - a connection carrier (1) having a mounting side (1a), - a light source (2) fastened and electrically connected to the mounting side (1a) of the connection carrier (1), - a cover piece (3) which locally covers the connection carrier (2) on the mounting side (1a) of the connection carrier and laterally encloses the light source (2), - an optical element (4) having a central region (41), which central region is arranged downstream of the light source (2) on the mounting side (1a) of the connection carrier (1), wherein - precautions are taken to prevent light (6, 61) from entering the central region (41) of the optical element (4).

Description

[0001] A light-emitting device is proposed. The light-emitting device can be used, for example, in motor vehicle headlights or in projection devices. The light-emitting device is designed to emit light in a wavelength range from infrared radiation to ultraviolet radiation during operation. For example, the light-emitting device is designed to emit white light during operation.

[0002] The object to be achieved is to provide a light-emitting device that emits particularly high-quality light.

[0003] According to at least one embodiment of the light-emitting device, the light-emitting device includes a connection carrier. The connection carrier is, for example, a circuit board with contacts for contacting the electrical components of the light-emitting device. The connection carrier can be, for example, a metal-core circuit board, a ceramic carrier with metal contacts, or a printed circuit board. The connection carrier includes a mounting surface on the mounting side, and the electrical components of the light-emitting device are applied to this mounting surface. In addition to the electrical properties of the connection carrier for contacting the electrical components of the device, the connection carrier also has a mechanical load-bearing function in the light-emitting device. That is, at least some components of the light-emitting device are mechanically supported and carried by the connection carrier.

[0004] According to at least one embodiment, the light-emitting device includes a light source. The light source is configured to generate electromagnetic radiation, in particular the light emitted by the light-emitting device during operation. The light-emitting device can include one or more light sources, which can be configured to be the same as or different from each other.

[0005] For this purpose, the light source includes, for example, one or more light-emitting diode chips. The light-emitting diode chips can be, for example, pixelated light-emitting diode chips. The pixelated light-emitting diode chips have two or more emission regions that can be separately controlled from each other. For example, the emission regions of the pixelated light-emitting diode chips are arranged at the grid points of a regular grid.

[0006] One or more light-emitting diode chips of the light source include, for example, an active region, in which primary radiation in the wavelength range of UV radiation and / or blue light is generated during operation. A conversion element can be arranged downstream of the active region, which converts a part of the primary radiation into secondary radiation in a lower energy wavelength range in order to emit mixed light (for example, white mixed light) as a whole.

[0007] The light source of the light-emitting device is fastened and electrically connected to the mounting side of the connection carrier. For example, the light source is fastened to the mounting surface of the connection carrier by means of solder or an adhesive.

[0008] According to at least one embodiment of the light-emitting device, the light-emitting device includes a cover member that locally covers the connection carrier on the mounting side thereof and laterally surrounds the light source. Here, the cover member can, for example, completely surround the light source laterally, without covering the light source in the vertical direction. The lateral direction extends, for example, parallel to the main extension direction of the connection carrier and / or parallel to the mounting surface of the connection carrier. The vertical direction extends perpendicular to the lateral direction.

[0009] For this purpose, the cover member can be in direct contact with the mounting surface of the connection carrier. The cover member covers, for example, connection elements (such as wires) through which the electrical components of the light-emitting device are conductively connected to the connection carrier. For example, the cover member covers the wires through which the light source is conductively connected to the connection carrier. The cover member can especially surround the light source in a ring or frame manner. For example, the cover member is a top encapsulation member.

[0010] According to at least one embodiment of the light-emitting device, the light-emitting device includes an optical element having a central region that is disposed downstream of the light source on the mounting side of the connection carrier. In other words, the light source is disposed between the connection carrier and the optical element. The optical element has a central region that can be laterally surrounded by an edge region of the optical element. The light incident on the optical element in the central region is subjected to a targeted optical influence by the optical element. The light incident in the edge region is affected in an undesirable manner, such that the radiation incident in the edge region or the radiation incident from the edge region into the central region of the optical element is undesirable.

[0011] The optical element can be, for example, an optical lens, a Fresnel lens, a reflector, a transparent plate, or a condenser. The optical element is used, for example, to map the light emitted by the light source during operation into the far field, that is, to project the light density distribution of the light source into the far field. The optical element is formed of a transparent material (such as glass or plastic).

[0012] According to at least one embodiment of the light-emitting device, at least one preventive measure is taken to prevent light from entering the central region of the optical element. The light can especially be reflected light. In other words, then preventive measures are taken such that only the light directly emitted by the light source enters the central region of the optical element. The light reflected at least once at another component of the device (such as at the connection carrier) is prevented from entering the central region by the preventive measure. In addition, the preventive measure can prevent the reflected light from entering the acceptance angle of a subsequent optical system.

[0013] Additionally or alternatively, the light can be partially non-reflected light, which is prevented from entering the central region.

[0014] According to at least one embodiment, a light-emitting device is proposed, which has

[0015] - a connection carrier having a mounting side,

[0016] - A light source, which is fastened and electrically connected to the mounting side of the connection carrier,

[0017] - A cover, which locally covers the connection carrier on the mounting side and laterally surrounds the light source,

[0018] - An optical element having a central region, which is arranged downstream of the light source on the mounting side of the connection carrier, wherein

[0019] - Preventive measures are taken to prevent light from entering the central region of the optical element.

[0020] The light-emitting device described herein is in particular based on the following considerations. When using the light-emitting device, for example when using the light-emitting device in a motor vehicle headlight or in a projection device, the light density distribution of the light source should be directly mapped into the far field. Here, the following problem occurs: In the edge region of the light-emitting field, unwanted sharp lines or blurred regions are mapped into the far field. For example, this unwanted mapping into the far field is formed for the following reasons: Light reflected at other components of the device reaches the central region of the optical element and is thus mapped into the far field. For example, unwanted reflections into the far field can occur at the cover and / or at the connection carrier.

[0021] The light-emitting device described herein is now based on the following insight: Preventing a part of the reflected light and / or non-reflected light from entering the central region of the optical element causes that the light density of the projection of the light source into the far field can be achieved without disturbing artifacts.

[0022] According to at least one embodiment of the light-emitting device, the cover is designed to guide the light emitted by the light source away from the central region of the optical element. That is, in this embodiment, the cover is configured, for example, in terms of its shape, its optical properties, and / or its material such that preventive measures are taken to prevent, for example, reflected light from entering the central region of the optical element. In particular, by the preventive measures, it can be caused that the light is guided away from the acceptance angle of the subsequent optical system.

[0023] For example, the cover can have a thickness that at least initially increases in the direction away from the light source. In this way, the cover can have an outer surface on its side facing away from the connection carrier, which reflects the light incident from the light source in a manner away from the central region of the optical element.

[0024] The outer surface extends, for example, at least locally inclined to the mounting surface of the connecting carrier. For example, the outer surface encloses an acute angle with the mounting surface of the connecting carrier. Thus, the cross-section of the cover can be configured in a wedge shape, for example. In this way, the light emitted by the light source is not directed towards the central region of the optical element, but is directed to the edge region of the optical element or is directed to leave the optical element laterally, wherein the central region is particularly arranged directly above the light source and the edge region can be arranged above the cover.

[0025] For this purpose, the cover can particularly have a reflective outer surface on the side facing away from the connecting carrier, and this reflective outer surface reflects the incident light in a directed manner. For example, this can be achieved by forming the cover from a reflective material and / or having a smooth surface at the surface of the cover facing away from the mounting side.

[0026] According to at least one embodiment of the light-emitting device, the cover has a light-reflecting layer at its outer surface. In this embodiment, the outer surface of the cover does not have to be configured in a reflective manner, but rather an additional layer is applied to the cover, and this additional layer is designed to reflect the incident light as directionally as possible. For example, the light-reflecting layer is formed by a layer sequence of layers with different refractive indices, and these layers are each formed from an electrically insulating material (such as metal oxides and / or metal nitrides and / or semiconductor oxides and / or semiconductor nitrides). For example, the reflective layer can include alternating sub-layers formed from silicon oxide and silicon nitride. Alternatively, the light-reflecting layer can be a metal layer, which includes, for example, silver and / or aluminum or consists of one of these materials.

[0027] According to at least one embodiment of the light-emitting device, an optical body is arranged between the light source and the cover, and this optical body guides the light emitted by the light source away from the central region of the optical element. The optical body can be a reflector, for example. The reflector can directly adjoin the cover on the side of the cover facing the light source or there can be a gap between the cover and the optical body.

[0028] The optical body is formed from a directionally reflective material, for example, or is coated with a directionally reflective material at its outer surface. The cross-section of the optical body can be configured in a wedge shape, for example, where the wedge tapers towards the light source. The optical body then has an outer surface that extends inclined to the mounting surface of the connecting carrier.

[0029] In addition, the optical body can be a light-guiding element that guides the light incident on the optical body away from the central region of the optical element. In this case, the optical body can include, for example, a light conductor or be a light conductor. In addition, the optical body can be a light-refracting element (i.e., a prism, for example) that refracts the incident light away from the central region of the optical element.

[0030] According to at least one embodiment of the light-emitting device, the optical element has a light-absorbing layer in an edge region on the side of the optical element facing the connection carrier, and the edge region laterally surrounds the central region. The light-absorbing layer is designed to absorb light. In other words, in this embodiment, the central region of the optical element is surrounded by an absorption layer on the side of the optical element facing the mounting carrier, which absorbs the incident light. As a result, the light incident in the edge region cannot reach the central region of the optical element. In this way, precautions are taken to prevent, for example, reflected light from being incident on the central region of the optical element. The light-absorbing layer is composed, for example, of a light-absorbing material that absorbs at least 90% of the incident visible light. Then, the light-absorbing layer can also advantageously absorb non-reflected light and in this way prevent it from being incident on the central region. For example, organic optical edge lacquers or inorganic coatings can be considered as materials for forming the light-absorbing layer.

[0031] According to at least one embodiment of the light-emitting device, the optical element is covered with a light-reflecting layer in the edge region on the side of the optical element facing the connection carrier, which light-reflecting layer is designed to reflect reflected light. In this way, light incident into the optical element in the edge region cannot reach the central region of the optical element, so that precautions are taken to prevent, for example, reflected light from incident into the central region of the optical element. The light-reflecting layer is formed, for example, with a material that reflects at least 85% of the incident visible light. The light-reflecting layer can then also advantageously reflect non-reflected light and in this way prevent it from incident into the central region. The material can, for example, be a silver or aluminum coating and / or a dielectric coating.

[0032] According to at least one embodiment of the light emitting device, an aperture is arranged between the light source and the optical element, which aperture covers the light source and the cover. Precautions are taken by the aperture to prevent light from being incident on the central area of ​​the optical element. For this purpose, the aperture has an optical opening, in particular in the area of ​​the central area of ​​the optical element (i.e., for example, directly below the central area of ​​the optical element), through which the light of the light source can pass. The opening is then arranged, for example, directly above the light source. The aperture has a light-proof area directly above the cover, which prevents a portion of the light reflected at the cover and / or non-reflected light from being incident. In this way, light cannot reach the central area of ​​the optical element.

[0033] According to at least one embodiment, the aperture comprises a substrate and an opaque layer, wherein the opaque layer covers the substrate in the region above the cover, and the substrate is free of the opaque layer in the region above the light source. The substrate is formed, for example, with a light-transmitting material such as plastic or glass. In the region where the substrate is free of the opaque layer, the substrate may have, for example, an antireflection layer on its side facing the light source and / or on its side facing away from the light source, which prevents reflections at the substrate. In the region above the cover, the aperture is constructed in a way that is opaque to the light of the light source by the opaque layer at the substrate.

[0034] According to at least one embodiment of the light-emitting device, the cover projects relative to the light source on the mounting side. That is to say, the cover is configured, for example, to be thicker than the light source. In a vertical direction, for example, extending perpendicular to the mounting surface, the cover projects relative to the light source. In this way, the cover can mechanically protect the light source from damage. However, due to this structure, more light hits the cover compared to the case where the light source projects relative to the cover. Therefore, the preventive measures described herein have proven to be particularly advantageous, which prevent light from entering the central region of the optical element.

[0035] In the light-emitting device described herein, in particular, two or more of the preventive measures described herein for preventing light from entering the central region can be combined in one light-emitting device. Thus, the cover can be designed, for example, to guide the light emitted by the light source away from the central region of the optical element and to be able to arrange a diaphragm between the light source and the optical element, which further prevents light from entering the central region.

[0036] The light-emitting device described herein is particularly characterized in that the contrast of the light density projected into the far field is increased by avoiding mapping of unwanted reflections into the far field. In this way, the mapped light has a particularly high light quality.

[0037] Below, the light-emitting device described herein will be explained in more detail based on embodiments and the accompanying drawings.

[0038] Figure 1 、 2 Figures 3, 4, 5, 6 show embodiments of the light-emitting device described herein according to schematic cross-sectional views.

[0039] Identical, similar or identically acting elements are provided with the same reference signs in the drawings. The size ratios between the drawings and the elements shown in the drawings cannot be regarded as being drawn to scale. Rather, for better visibility and / or for better understanding, the individual elements can be shown exaggeratedly.

[0040] Figure 1 The schematic cross-sectional view and all the following cross-sectional views respectively show a part of the light-emitting device. The right half of the light-emitting device is currently shown. The left half of the light-emitting device is configured, for example, axially symmetrically thereto, with the axis of symmetry being perpendicular to the connecting carrier 1 and extending along the left edge of the figure.

[0041] Figure 1A light-emitting device described herein according to a first embodiment is shown in a schematic cross-sectional view. The light-emitting device includes a connection carrier 1 having a mounting side 1a. The connection carrier 1 is, for example, a circuit board. The light-emitting device further includes a light source 2. Currently, the light source 2 includes a plurality of light-emitting diode chips 21. The light-emitting diode chips 21 are, for example, pixelated light-emitting diode chips, which include pixels 22 that can be controlled separately from each other.

[0042] The light source is mechanically fastened and electrically connected on the mounting surface 11 of the connection carrier 1 at the mounting side 1a. For example, the light source can be conductively connected to the connection carrier 1 through contact lines (not shown).

[0043] The light-emitting device further includes a cover 3, which locally covers the connection carrier 2 at the mounting side 1a of the connection carrier and laterally surrounds the light source. For example, the cover completely surrounds the light source 2 in a lateral direction extending parallel to the main extension plane of the connection carrier 1. Here, the cover 3 protrudes relative to the light source 2 in a vertical direction extending perpendicular to the main extension plane of the connection carrier 1. The cover is formed, for example, of a plastic material. The cover 3 can in particular be configured in black or in color. The cover 3, for example, covers the contact lines by means of which the light source is conductively connected to the connection carrier 1. The cover 3 provides mechanical protection for the light source and other components (i.e., for example, the contact lines).

[0044] The light-emitting device further includes an optical element 4. The optical element 4 includes a central region 41, which is arranged downstream of the light source 2 at the mounting side 1a of the connection carrier. In addition, the optical element 4 includes an edge region 42 that completely surrounds the central region 41 in the lateral direction. The edge region 42 is arranged, for example, above the cover 3.

[0045] In addition, the light-emitting device includes a precaution for preventing reflected light 6 from entering the central region 41 of the optical element 4.

[0046] The light source 2 emits light 5 during operation. The light 5 partially strikes another component of the light-emitting device (currently, for example, partially strikes the cover 3), and is reflected there. In the present case, the shape of the cover is selected such that the cover 3 is designed to: guide the light 5 emitted by the light source 2 away from the central region 41 of the optical element, or reflect the emitted light such that the emitted light no longer falls within the acceptance angle of the optical system. Thus, a precaution is taken to prevent reflected light 6 from entering the central region of the optical element 4.

[0047] In Figure 1In the embodiment, this is achieved in such a way that the cover has an increasing thickness D in a direction away from the light source 2. In addition, the cover 3 has a reflective outer surface 3a on the side facing away from the connecting carrier 1, and this reflective outer surface reflects the incident light in a directional manner. Due to the increasing thickness, the outer surface 3a extends inclinedly to the mounting surface 11 at the mounting surface 1a of the connecting carrier 1. Thereby, the reflected light 6 is guided away from the central region 41.

[0048] In Figure 2 the embodiment, the cover 3 has a conventional shape. An optical body 7 is arranged between the light source 2 and the cover 3, and this optical body guides the light 5 emitted by the light source 2 away from the central region 41 of the optical element 4. Thereby, precautions are taken to prevent the reflected light 6 from entering the central region of the optical element 4 or to guide the reflected light away from the acceptance angle of the subsequent optical system. For example, the acceptance angle is 45°. Here, the optical body 7 completely surrounds the light source in the lateral direction. The cross-section of the optical body 7 is formed wedge-shaped. The optical body has a reflective, inclinedly extending outer surface 7a facing away from the connecting carrier 1, and this outer surface guides the reflected light 6 away from the central region 41.

[0049] Alternatively, the optical body 7 can be a light conductor, and this light conductor guides the incident light 5 past the optical element 4 by reflection to the light-emitting device. In this way, it is also ensured that no light is reflected into the central region 41 or no reflected light falls within the acceptance angle of the optical system.

[0050] Another embodiment of the light-emitting device described here is described in connection with Figure 3 the schematic cross-sectional view. In this embodiment, different from Figure 1 the embodiment, a light-reflecting layer 31 is applied to the cover 3 at the outer surface 3a of the cover. The light-reflecting layer 31 is designed to reflect the incident light 6 in a directional manner, so that precautions are taken to prevent the reflected light 6 from entering the central region 41 of the optical element 4 or no reflected light falling within the acceptance angle of the subsequent optical system.

[0051] Here, the advantage of using the light-reflecting layer 31 is that the surface of the cover 3 does not have to be reflective, but the reflectivity can be produced by the reflecting layer 31. Therefore, the surface of the cover 3 does not have to be formed particularly smoothly, for example, to achieve the desired reflection. Reflection at a rough surface causes fewer problems when mapped into the far field, because the reflection is presented diffusely by the rough surface.

[0052] Another embodiment of the light-emitting device described here is described in more detail in connection with Figure 4 the schematic cross-sectional view. Different from Figure 1In the embodiment of [description omitted], the device includes a diaphragm 8 having a substrate 81 and a light-impermeable layer 82. The diaphragm 8 is disposed between the light source 2 and the optical element 4 and covers the light source 2 and the cover 3. Here, the light-impermeable layer covers the substrate 81 in the region above the cover, and the substrate 81 has no light-impermeable layer in the region above the light source. The cover 3 can be configured reflectively, for example, as described in connection with Figure 1 In addition, a reflective layer 31 as described in connection with Figure 3 can be applied to the cover. Finally, a cover in a conventional form as described in connection with Figure 2 can be used as the cover. The light 6 reflected at the cover is absorbed or reflected by the light-impermeable layer 82, so that precautions are taken to prevent a part of the reflected light 6 and / or non-reflected light 61 from entering the central region 41 of the optical element 4.

[0053] Another embodiment of the light-emitting device described herein will be described in more detail in connection with Figure 5 a schematic cross-sectional view. In this embodiment, the optical element 4 has a light-absorbing layer 43 on the side facing the connection carrier 1 in the edge region 42, which laterally surrounds the central region 41, and the light-absorbing layer is designed to absorb a part of the reflected light 6 and / or non-reflected light 61. Thus, precautions are taken to prevent a part of the reflected light 6 and / or non-reflected light 61 from entering the central region 41 of the optical element 4. In the region of the optical element where the light-absorbing layer 43 is disposed, that is, on the lower side of the edge region 42 facing the connection carrier 1, the optical element 4 can extend particularly parallel to the mounting surface 11 of the connection carrier 1.

[0054] Another embodiment of the light-emitting device described herein will be described in more detail in connection with Figure 6 a schematic cross-sectional view. In this embodiment, the optical element 4 has a light-reflective layer 44 on the side facing the connection carrier 1 in the edge region 42, and the light-reflective layer is designed to reflect a part of the reflected light 6 and / or non-reflected light 6. Thereby, precautions are taken to prevent the reflected light 6 from entering the central region of the optical element 4. On the lower side of the edge region 42 of the optical element 4 facing the connection carrier 1, the outer surface of the optical element can extend obliquely to the mounting surface 11 of the connection carrier 1. For example, the outer surface is at least partially parallel to the outer surface 3a of the cover 3. In this way, the light reflected at the cover 3 can be emitted from the light-emitting device with particularly few reflections by directional reflection at the reflective layer 44.

[0055] In the light-emitting device described herein, in particular, the precautions described herein for preventing light from entering the central region 41 of the optical element 4 can be combined with each other. For example, the use of the diaphragm 8 as Figure 4 shown can be combined with that described in connection with Figure 1in combination with the special shape of the covering part 3 shown.

[0056] The present invention is not limited to the description made according to these embodiments. Rather, the present invention includes each new feature and each combination of features, which in particular includes each combination of features in the claims, even if the feature or the combination itself is not explicitly set forth in the claims or the embodiments.

[0057] This application claims the priority of German Patent Application DE 102020101038.9, the disclosure of which is incorporated herein by reference.

[0058] List of Reference Numerals

[0059] 1 Connecting carrier

[0060] 1a Mounting side of the connecting carrier

[0061] 11 Mounting surface of the connecting carrier

[0062] 2 Light source

[0063] 21 Light-emitting diode chip

[0064] 22 Pixel

[0065] 3 Covering part

[0066] 31 Light reflection layer of the covering part

[0067] 3a Gold

[0068] 4 Optical element

[0069] 41 Central region of the optical element

[0070] 42 Edge region of the optical element

[0071] 43 Light absorption layer of the optical element

[0072] 44 Light reflection layer of the optical element

[0073] 5 Light emitted by the light source

[0074] 6 Reflected light

[0075] 61 Non-reflected light

[0076] 7 Optical body

[0077] 7a Outer surface of the optical body

[0078] 8 Diaphragm

[0079] 81 Substrate

[0080] 82 Light-impermeable layer of the diaphragm

Claims

1. A light-emitting device having - a connection carrier (1) having a mounting side (1a), - a light source (2) fastened and electrically connected to the mounting side (1a) of the connection carrier (1), - a cover piece (3) that locally covers the connection carrier (2) on the mounting side (1a) of the connection carrier and laterally encloses the light source (2), - an optical element (4) having a central region (41), the central region being arranged downstream of the light source (2) on the mounting side (1a) of the connection carrier (1), wherein - preventive measures are taken to prevent reflected light (6) from entering the central region (41) of the optical element (4); - preventive measures are taken by means of a diaphragm (8) to prevent reflected light (6) from entering the central region (41) of the optical element (4); - the diaphragm (8) is arranged between the light source (2) and the optical element (4), and the diaphragm covers the light source (2) and the cover piece (3); - the diaphragm (8) has an optical opening directly below the central region (41) of the optical element (4), and - the light of the light source (2) passes through the optical opening.

2. The light-emitting device according to claim 1, wherein the cover piece (3) is designed to guide the light (5) emitted by the light source (2) away from the central region (41) of the optical element (4).

3. The light-emitting device according to claim 1 or 2, wherein the cover piece (3) has an increasing thickness (D) in a direction away from the light source (2).

4. The light-emitting device according to claim 1 or 2, wherein the cover piece (3) has a reflective outer surface (3a) on the side facing away from the connection carrier (1).

5. The light-emitting device according to claim 4, wherein the outer surface (3a) extends inclined to the mounting surface (11) of the mounting side (1a) of the connection carrier (1).

6. The light-emitting device according to claim 1 or 2, wherein the cover piece (3) has a light-reflecting layer (31) at its outer surface (3a).

7. The light-emitting device according to claim 1 or 2, wherein an optical body (7) is arranged between the light source (2) and the cover piece (3), and the optical body guides the light (5) emitted by the light source (2) away from the central region (41) of the optical element (4).

8. The light-emitting device according to claim 1 or 2, wherein the optical element (41) has an edge region (42) that laterally encloses the central region (41).

9. The light-emitting device according to claim 8, wherein the optical element (4) is covered in the edge region (42) on the side of the optical element (4) facing the connection carrier (1) with a light-absorbing layer (43) designed to absorb light (6, 61).

10. The light-emitting device according to claim 8, The optical element (4) is covered in the edge region (42) on the side facing the connection carrier (1) with a light-reflecting layer (44) designed to reflect light (6, 61).

11. The light-emitting device according to claim 1, wherein the diaphragm (8) comprises a substrate (81) and a light-impermeable layer (82), wherein the light-impermeable layer (82) covers the substrate (81) in the region above the covering (3), and the substrate (81) is without the light-impermeable layer (82) in the region above the light source (2).

12. The light-emitting device according to claim 1 or 2, wherein the covering (3) protrudes relative to the light source (2) on the mounting side (1a).

13. The light-emitting device according to claim 1 or 2, wherein the light source (2) comprises two or more pixelated light-emitting diode chips (21).

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