DEVICE FOR EMITTING LIGHT

Description

[0001] The invention relates to a device and an arrangement for emitting light, in particular for curing substances which harden under irradiation with light, in particular UV light, according to patent claim 1 and patent claim 8, respectively.

[0002] It is known from the prior art to rapidly cure liquid coating materials such as adhesives, varnishes, or paints using high-energy radiation. The radiation sources for this are usually special lighting fixtures that emit UV light, particularly UV-A light. Common UV lamps of this type include mercury vapor lamps. UV light-emitting diodes are also available for such applications. These offer the advantage of being mercury-free and particularly small, thus requiring little space. However, if such light-emitting diodes are operated for an extended period, they heat up considerably, which can lead to overheating and damage.

[0003] US 2012 / 307505 A1 discloses the preamble of claim 1.

[0004] US 2018 / 070436 A1 and US 9 605 812 B2 disclose devices for emitting light with a thermistor.

[0005] The object of the invention is therefore to provide a device for emitting light which ensures light emission from a lighting fixture over a longer period of time without there being a risk of the lighting fixture overheating.

[0006] The invention solves this problem with a device for emitting light, in particular for curing substances that harden under irradiation with light, in particular UV light, having the features of patent claim 1.

[0007] A particularly energy-saving design of the device for emitting light can be ensured if the lighting fixture comprises a light-emitting diode designed to emit UV light, in particular UV-A light, preferably in a wavelength range of 315 to 380 nm. The use of a light-emitting diode as a lighting fixture is advantageous not only due to its comparatively low power consumption, but also because light-emitting diodes have a comparatively long service life and are characterized by a particularly small and compact design.

[0008] A particularly compact and stable construction can be achieved in a device for emitting light according to the invention if the carrier element is designed as a printed circuit board.

[0009] In order to ensure a simple connection of the contacts of the thermistor to the electrical contacts of the lighting fixture, the invention provides that the carrier element has at least two passages, wherein the two contacts, in particular contact pins of the thermistor, are guided through the passages to the electrical connections of the lighting fixture.

[0010] In order to ensure that the heat energy generated in the lighting fixture is dissipated as quickly as possible, the heat sink can be made of copper or a copper alloy.

[0011] An effortless installation of a device according to the invention for emitting light as a component in, for example, industrial robots can be ensured if the heat sink has at least one connection point for forming a material-locking connection, in particular by soldering or gluing, in its area facing away from the thermistor.

[0012] A particularly efficient removal of heat energy generated at the lighting fixture is ensured if the connection between the thermistor and the heat sink is made by means of a heat-conducting and electrically insulating connecting agent, in particular an adhesive, preferably a high-temperature-resistant heat-conductive adhesive.

[0013] To ensure particularly efficient heat transfer from the thermal contact surface of the lighting fixture to the heat sink, the heat sink can be provided with a projection, the shape and height of which are adapted to the shape and height of the recess in the support element, so that the projection is guided through the recess to the thermal contact surface of the lighting fixture and is in flat contact with the thermal contact surface. This design of the heat sink is particularly advantageous, for example, when high-performance light-emitting diodes are used as lighting fixtures, since these have a higher thermal energy dissipation compared to conventional light-emitting diodes.

[0014] The invention further relates to an arrangement for emitting light, in particular for curing substances that harden under irradiation with light, in particular UV light. According to the invention, a plurality of devices according to the invention for emitting light, a power source for supplying the devices with power, and a driver connected downstream of the power source are provided. The devices are connected in series and connected to the driver, and the driver is designed to set a constant current flow through the devices.

[0015] With an arrangement according to the invention, particularly rapid curing of, for example, UV-curing adhesives can advantageously be achieved even on larger surfaces, since the performance of the arrangement can be multiplied compared to the performance of a single device by interconnecting a number of devices together.

[0016] Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings.

[0017] The invention is schematically illustrated below in the drawings using particularly advantageous, but not restrictive, embodiments and is described by way of example with reference to the drawings.

[0018] The following shows schematically: Fig. 1 a side view of an embodiment of a device according to the invention for emitting light, Fig. 2 a second side view of the device Fig. 1 , Fig. 3 a top view of the device Fig. 1 , Fig. 4 an exploded view of the device Fig. 1 and Fig. 5 an oblique view of the device Fig. 1 .

[0019] In the Fig. 1 bis Fig. 5 An embodiment of a device 100 according to the invention for emitting light is shown. In the illustrated embodiment, the device 100 comprises an electrical lighting fixture 1 with a thermal contact surface 11 and two electrical connections 12a, 12b. The lighting fixture 1 is arranged on a support element 2, and the thermal energy generated during the light emission is dissipated from the lighting fixture 1 via the thermal contact surface 11. For this purpose, the support element 2 has a recess 21 in the region of the thermal contact surface 11 of the lighting fixture 1.

[0020] In the illustrated embodiment, the recess 21 has an elongated shape, but can alternatively also have a round shape, for example. Furthermore, instead of a single recess 21, a plurality of recesses 21 can be provided, which are arranged, for example, one behind the other in the region of the thermal contact surface 11.

[0021] In the illustrated embodiment, the device 100 further comprises a heat sink 3, which is thermally connected to the thermal contact surface 11 of the lighting fixture 1 in the region of the recess 21 in the support element 2. In this way, thermal energy generated in the lighting fixture 1 is transferred to the heat sink 3 via the contact surface 11.

[0022] The device 100 further comprises a thermistor 4, which is electrically connected to the electrical terminals 12a, 12b of the lighting fixture. The thermistor 4 is thermally connected to the heat sink 3 and simultaneously electrically insulated from the heat sink 3.

[0023] Such a device 100 for emitting light can be used, for example, to cure hardening substances under irradiation with light such as UV light. In the illustrated embodiment, it is particularly advantageous in this context that the device 100 comprises a light-emitting diode 13 as the lighting element 1. In this way, the device 100 can be designed to be particularly small and compact, so that, compared to previously known mercury vapor lamps used for curing substances, it not only does not require mercury, but also requires significantly less space and can thus be easily installed as a component, for example, in robots.

[0024] In the illustrated embodiment, the lighting fixture 1 or the light-emitting diode 13 is specifically a UV light-emitting diode designed to emit UV-A light in a wavelength range of 315 to 380 nm. The semiconductor crystal of the light-emitting diode 13 is applied to a square substrate in the illustrated embodiment, which has an edge length of a few millimeters, for example, 3 mm, as shown in Fig. 3 bis Fig. 5 is evident.

[0025] This lighting fixture 1 is arranged on a carrier element 2, which is designed as a printed circuit board and has an elongated recess 21 in the region of the thermal contact surface 11 of the lighting fixture 1, which is located on the underside of the substrate, as shown in Fig. 3 can be seen.

[0026] The electrical connections 12a, 12b of the electrical lighting fixture 1 are arranged laterally on the substrate of the light-emitting diode 13 in the embodiment shown and the carrier element 2 has, according to the invention, two passages 23a, 23b through which the contacts of the thermistor 4 are led to the electrical connections 12a, 12b of the lighting fixture 1 (see Fig. 3, Fig. 5 ). In the illustrated embodiment, the thermistor 4 has two contact pins 41a, 41b, which extend through the round openings 23a, 23b in the carrier element 2 and are led to the electrical connections 12a, 12b (see Fig. 2, Fig. 5 ).

[0027] Alternatively, depending on the field of application, in a device 100 according to the invention, the lighting body 1 can also comprise a different illuminant or a differently designed light-emitting diode 13 which has a different structure or is designed to emit light in a different wavelength range.

[0028] In the illustrated embodiment, the heat sink 3 is made of copper, since copper has high thermal conductivity. Alternatively, in all embodiments of a device 100 according to the invention, the heat sink can be made of a copper alloy or other materials with high thermal conductivity.

[0029] The heat sink 3 has a projection 33, at which the heat sink 3 is in contact with the thermal contact surface 11 of the lighting fixture 1. As shown in Fig. 4 As can be seen, the projection 33 is adapted in its shape and height to the shape and height of the recess 21 in the carrier element 2 such that it projects through the carrier element 2 and is guided to the thermal contact surface of the lighting body 1.

[0030] In the illustrated embodiment, the shape of the heat sink 3 is composed of a half-cylinder and a half-truncated cone, with the heat sink 3 having a connection point 31 for forming a materially bonded joint. The connection point 31 is located in the area of ​​the heat sink 3 facing away from the thermistor 4, so that a device 100 according to the invention can be easily integrated into larger systems or devices, for example, by soldering or gluing.

[0031] As already mentioned, the thermistor 4 is thermally conductively connected to the heat sink 3 and at the same time is electrically insulated from the heat sink 3. In the exemplary embodiment shown, this is achieved by establishing the connection between the thermistor 4 and the heat sink 3 using a thermally conductive and electrically insulating connecting means. In the example shown, the connecting means is an adhesive, such as a synthetic resin, which is mixed with ceramic or mineral fillers so that heat is conducted via the adhesive but no electrical current can flow. Such adhesives offer the further advantage of being highly temperature-resistant, for example up to 200°C.

[0032] If, during operation of the device 100, current flows through the electrical terminals 12a, 12b of the lighting fixture 1, this generates UV light in a selected wavelength range, which also generates heat energy. Since excessively high temperatures can drastically shorten the service life of light-emitting diodes 13 or even lead to no longer emitting UV light in the desired wavelength range, the thermistor 4 contacts the electrical terminals 12a, 12b of the lighting fixture 1. In the cold state, the resistance of the thermistor 3 is comparatively high, but decreases further with increasing temperature according to a characteristic curve characteristic of the respective thermistor 4.

[0033] If the lighting fixture 1 generates heat energy during operation, this is transferred to the heat sink 3 via the thermal contact surface 11. The contact between the thermal contact surface 11 and the heat sink 3 is established, for example, by soldering. The heat sink 3 is connected to the thermistor 4 in a thermally conductive manner, so that the temperature of the thermistor 4 increases when the lighting fixture 1 generates heat energy and transfers it to the heat sink 3. In this way, the resistance decreases or the electrical conductivity of the thermistor 4 increases according to the characteristic curve of the thermistor 4.

[0034] Particularly advantageous for irradiating larger areas with light, in particular UV light, for curing radiation-curing substances is an arrangement according to the invention for emitting light, comprising a plurality of devices 100, a power source for supplying the devices 100 with power, and a driver connected downstream of the power source. In this way, it is possible, for example, to connect up to 15 devices 100 in series, which are connected to the driver. The driver ensures a constant current flow through the devices 100. The illumination intensity can be correspondingly increased with such an arrangement, thus ensuring faster curing. In addition, larger surface areas can also be irradiated in this way.

Claims

1. Light-emitting device (100), in particular for the hardening of substances which harden when irradiated by light, in particular UV light, comprising: - an electrical light fixture (1) with at least one heat contact surface (11) and at least two electrical connections (12a, 12b), - wherein heat energy generated during the light emission can be dissipated over the heat contact surface (11), - wherein the light fixture (1) is mounted on a support element (2), - a heat sink - wherein the support element (2) has at least one recess (21) in the area of the heat contact surface (11) of the light fixture (1), - wherein the heat sink (3) is heat-conductively connected to the heat contact surface (11) of the light fixture (1) in the area of the recess (21) in the support element (2), and - wherein the device (100) comprises a thermistor (4) which is electrically conductively connected to the electrical connections (12a, 12b) of the light fixture (1), wherein the thermistor (4) is heat-conductively connected to the heat sink (3) and at the same time is electrically insulated from the heat sink (3), characterized in that the support element (2) has at least two passages (23a, 23b), wherein the two contacts, in particular contact pins (41a, 41b) of the thermistor (4), are guided through the passages (23a, 23b) to the electrical connections (12a, 12b) of the light fixture (1).

2. Device (100) according to claim 1, characterized in that the light fixture (1) comprises a light-emitting diode (13) which is designed to emit UV light, in particular UV-A light, preferably in a wavelength range of 315 to 380 nm.

3. Device (100) according to claim 1 or 2, characterized in that the support element (2) is designed as a printed circuit board.

4. Device (100) according to any one of the preceding claims, characterized in that the heat sink (3) is made of copper or a copper alloy.

5. Device (100) according to any one of the preceding claims, characterized in that the heat sink (3) has at least one connection point (31) for forming a cohesive bond, in particular by brazing or gluing, in its area facing away from the thermistor (4).

6. Device (100) according to any one of the preceding claims, characterized in that the bond between the thermistor (4) and the heat sink (3) is made by means of a heat-conducting and electrically insulating bonding agent, in particular an adhesive, preferably a high-temperature-resistant, heat-conductive adhesive.

7. Device (100) according to any one of the preceding claims, characterized in that the heat sink (3) has a projection (33), wherein the projection (33) is adapted in its shape and height to the shape and height of the recess (21) in the support element (2), so that the projection (33) is guided through the recess (21) to the heat contact surface (11) of the light fixture (1) and is in flat contact with the heat contact surface (11).

8. Arrangement for emitting light, in particular for the hardening of substances which harden when irradiated by light, in particular UV light, comprising: a plurality of light-emitting devices (100) according to any one of claims 1 to 7, a power source for supplying the devices (100) with power, and a driver connected downstream from the power source, wherein the devices (100) are connected in series and connected to the driver, and wherein the driver is designed to adjust a constant power flow through the devices (100).