DEVICE FOR EMISSION OF ELECTROMAGNETIC RADIATION, IN PARTICULAR UV RADIATION

Description

[0001] The invention relates to a device for emitting electromagnetic radiation, in particular UV radiation, which has at least one radiation medium formed by at least one light-emitting diode, preferably by several light-emitting diodes, which emits radiation only in non-visible wavelengths, wherein the device includes a device for detecting a malfunction of the light-emitting diode.

[0002] Lamps with ultraviolet-emitting LEDs are known from DE 10 2004 043 295 B4, EP 1 623 213 B1, WO 2004 / 097385 A1, and US 8,616,722 B2. They are used for the visual inspection of workpiece surfaces, in particular for the detection of contaminants, for penetrant testing, and for fluorescent magnetic particle testing.

[0003] In visual inspection, particularly when examining workpiece surfaces using the fluorescent penetrant method, defects on workpiece surfaces are made visible by excitation with ultraviolet radiation using a fluorescent agent. The inspection is usually carried out in the dark, at an ambient light level of less than 20 lux, because humans have higher contrast sensitivity in visual perception during mesopic (twilight vision) and scotopic (night vision), and a high contrast between the surface being examined and the excited fluorescence allows for better inspection.

[0004] German patent DE 10 2009 029 930 B3 describes a method for detecting the failure of at least one LED.

[0005] DE 103 26 369 A1 describes a light table for evaluating material samples.

[0006] A warning system for lighting devices is known from US Patent 2012 / 105228 A1. The lighting devices to be monitored can have different light sources, in particular LEDs, which can emit both visible and invisible light. Furthermore, the warning system includes a detection module that records various operating parameters of the lighting device and the light sources. According to one embodiment, the lighting device is switched off upon detection of a hazardous situation. Such a hazardous situation could be an excessively high temperature of the lighting device.

[0007] The invention is based on the objective of creating a device of the type mentioned above, which ensures that it is only used if it functions flawlessly.

[0008] A device that solves this problem is, as defined in claim 1, characterized in that the device is configured to automatically shut down the entire device or at least the at least one light-emitting diode when the functional error is detected by means of the detection device.

[0009] In a preferred embodiment of the invention, the at least one light-emitting diode is provided to emit only UV radiation (wavelength range 200 to 400 nm) and / or IR radiation (wavelength range 780 to 50 µm). In an embodiment outside the scope of the claimed invention, a light-emitting diode may be provided to emit blue-violet radiation (wavelength range 380 to 490 nm).

[0010] Unlike conventional mercury vapor lamps used to emit UV radiation, where a malfunction is relatively easy to detect because they either function correctly or fail completely, light-emitting diodes repeatedly present the problem that their radiation intensity changes, e.g., that the radiation intensity fluctuates or that the light-emitting diodes flicker, so that the invention proves to be particularly advantageous for devices with light-emitting diodes.

[0011] Furthermore, if the device has several of the light-emitting diodes as the radiation medium, a malfunction of one or more of the light-emitting diodes, which also leads to a reduction in the light intensity, can also be detected.

[0012] The device is expediently equipped with a control and / or regulating device that switches off the device or the radiation medium upon detection of a malfunction.

[0013] For example, if a malfunction is detected in one of several circuits through which the radiation medium is supplied and in which preferably one or more LEDs are arranged, not only that one circuit, but all circuits are switched off so that the radiation medium as a whole can no longer emit radiation.

[0014] This advantageously prevents work from continuing with a malfunctioning device. Errors during testing, especially visual inspection, are avoided.

[0015] The invention solves the problem that, when using known devices, it is not readily apparent if the radiation emitting non-visible light does not function correctly, since the human eye does not immediately perceive, for example, a reduced luminous intensity, changes in the wavelengths of the radiation, flickering, a partial failure of the radiation emitting medium, or a change in a wavelength or wavelength range with which the radiation emits.

[0016] The detection device, which identifies malfunctions, enables appropriate measures to be taken in the event of a failure. This prevents defects from occurring during use of the device due to the malfunction, such as overlooking defects or, if the device is used for drying objects or curing materials, preventing the intended drying or curing process.

[0017] In one embodiment of the invention, the detection device is configured for the continuous monitoring of the radiation medium for operational errors, wherein the device is preferably checked for functional errors at regular intervals, e.g., every 10 ms. Advantageously, this allows functional errors to be detected even if they only occur after the device has been put into operation, particularly during operation.

[0018] Advantageously, the device, preferably the control and / or regulating unit, is configured to indicate a malfunction upon detection, for example, by means of a visual, tactile, or audible warning signal. It would also be conceivable to display information characterizing the malfunction, for example, on a screen. For instance, it could indicate which of the LEDs is not functioning correctly, and / or the type of malfunction, such as flickering, failure, or the like. The detection device can be configured to send a signal to the control and / or regulating unit upon detecting a malfunction.

[0019] In a further embodiment of the invention, the detection device is configured for monitoring the measurement of an electrical voltage drop across the radiation medium, the measurement of an electric current flowing through the radiation medium, the measurement of heating or temperature of the device generated by the radiation medium, preferably in the vicinity of the radiation medium, the measurement of the intensity with which the radiation medium emits radiation, and / or the measurement of the wavelength and / or wavelength range of radiation emitted by the radiation medium.

[0020] If several of the radiation sources are arranged and connected in a common circuit, the voltage drop or current could also be measured for the entire circuit.

[0021] To measure the heating, the detection device expediently includes a temperature sensor, preferably a platinum resistance thermometer, which is arranged on or near the radiation medium. It has proven particularly suitable to arrange the temperature sensor on a radiation medium support of the device, which is preferably formed by or connected to a metallic heat sink.

[0022] The detection device is expediently equipped with a radiation sensor, preferably a photocell, a photodiode, a phototransistor or a CMOS or CCD sensor, for measuring the intensity and / or the wavelength or wavelength range of the radiation.

[0023] Advantageously, the radiation medium is preferably provided with a filter for adjusting the respective wavelength range.

[0024] In a further embodiment of the invention, the device includes, in addition to the radiation medium, a means for emitting visible light, preferably white light. The device can switch between illumination with visible light and invisible light to allow switching between different views under white light and visible light during visual inspection.

[0025] Advantageously, the device is designed to automatically shut down not only the radiation source but also the means for emitting visible light when the malfunction is detected by the detection device.

[0026] The device is preferably configured to change the intensity at which the radiation source emits radiation independently of the intensity at which the visible light emission source emits radiation. Advantageously, the intensities of individual or all of the radiation sources can be adjusted separately.

[0027] In one embodiment of the invention, the device is configured to increase or decrease the intensity of at least one of the radiation means and at the same time to keep the intensity of at least one other of the radiation means constant or to decrease or increase it in the opposite direction to the first-mentioned radiation means.

[0028] Such intensity changes allow, on the one hand, one radiation source to be added to another, and on the other hand, from one radiation source to another, and thus from irradiation in one wavelength range to another.

[0029] Advantageously, the aforementioned control and / or regulating device is further provided for adjusting the intensity with which the radiation source and, if applicable, the emission device emit radiation. The control and / or regulating unit preferably comprises at least one constant current controller that operates on the basis of electrical and electronic switching and control circuits. The radiation source, in particular the LED, can thereby be operated particularly efficiently because the constant current controller allows the operating current of the respective radiation source, especially the LED or the LED circuit, to be measured and kept constant within narrow limits. Advantageously, the constant current controller can generate the constant current from an alternating and / or direct current voltage. The intensity with which the LED emits is preferably changed using pulse-width modulation. For this purpose, the device preferably includes a pulse-width modulation controller.Alternatively or additionally, the current intensity could be changed.

[0030] Furthermore, the control and / or regulating device may include a control mechanism that can reduce or shut off the power of the device or individual parts of the device depending on the temperature, in order to protect the device, in particular the radiation medium and / or the control and / or regulating device, from overheating. For cooling, the device could additionally or alternatively be equipped with a fan, which is preferably controllable and / or regulated by the control and / or regulating device. Advantageously, the device is also equipped for the detection of a malfunction and corresponding monitoring, preferably by means of the detection device or the control and / or regulating device.

[0031] Advantageously, the device for indicating the operating state of the radiation source is configured to indicate the operating state of each radiation source, provided that several radiation sources are provided. Alternatively or additionally, the device may indicate whether the respective radiation source is emitting radiation or not, i.e., in particular, whether it is switched on or off.

[0032] In a further embodiment of the invention, the device comprises an adjustment mechanism designed to regulate the intensity of the radiation emitted by the respective radiation medium as a function of the device's temperature. Advantageously, this compensates for a reduction in intensity that occurs with increasing temperature.

[0033] The device expediently comprises at least one housing, preferably designed to hold the radiation medium, at least one control element, at least one optical system, preferably comprising at least one lens, and / or at least one coolant, preferably a fan, a heat exchanger and / or a cooling plate.

[0034] In one embodiment of the invention, the device can be used in mobile and / or stationary applications. It can be a handheld and / or stand-alone device, or a device that can be permanently installed, for example, on a bracket or a wall.

[0035] While in a particularly preferred embodiment of the invention a device for operating the apparatus is integrated into the housing, it would also be conceivable to provide it outside the housing, wherein the apparatus preferably comprises at least one housing for the radiation means, at least one control cabinet or switch housing, and / or at least one operating element. Advantageously, the operating device has at least one control element that can be operated by hand or foot, by means of which the intensity of at least one of the radiation means can be changed.

[0036] The device can be powered by at least one external or integrated DC and / or AC power source.

[0037] The invention is explained in more detail below with reference to an exemplary embodiment and the accompanying drawings relating to that embodiment. The drawings show: Fig. 1 shows a side section of a device according to the invention, Fig. 2 shows a front view of the device according to the invention. Fig. 1 , and Fig. 3 a rear view of the device according to Fig. 1 .

[0038] One in the Figures 1 to 3 The device 1 according to the invention comprises eight UV LEDs 2, which are provided for the emission of UV radiation (wavelength range 200–400 nm), and eight white light LEDs 6, which are provided for the emission of white light (wavelength range 380–780 nm). Optical components 4 are arranged in front of the LEDs 2 and 6 to influence the respective beam paths emanating from the LEDs. A front panel 7 is arranged behind the optical components 4 in the direction of radiation. This front panel 7 is connected to a housing 9 of the device 1 via fastening means 10 and is provided with filters 8 for each of the UV LEDs 2.

[0039] The LEDs 2 and 6 are soldered onto a carrier board 26, which is mounted on a heat sink 11. The heat sink 11 is connected via standoffs 12 to a circuit board 13, which carries several electronic components, e.g., a microcontroller. An indicator LED 14 is also mounted on the circuit board 13, which, as explained in more detail below, is intended to indicate an operating state of the device 1. A light guide 15 is arranged between a rear side of the housing 9 and the indicator LED 14, by means of which radiation from the indicator LED 14 can be directed to the rear side.

[0040] Immediately next to each of the UV LEDs 2, a temperature sensor, for example a platinum measuring resistor, is arranged on the carrier board 26, which measures the temperature in order to determine any heating caused by the respective UV LEDs 2.

[0041] Furthermore, an optical sensor (not shown here), e.g. a CCD sensor, can be arranged on the inside of the front glass 7, e.g. diagonally opposite each of the UV LEDs 2.

[0042] The electronic components form a control and / or regulation device 4, which is configured to control and / or regulate the intensities at which the LEDs 2, 6 emit light. The control and regulation device 4 is further designed to change the intensities at which the UV LEDs 2 and the white light LEDs 6 emit light separately from each other by means of pulse width modulation and / or by changing the intended current.

[0043] The electronic components also form a detection device 3, which is connected to the temperature sensor 5 for the detection of functional errors during the operation of the device 1.

[0044] The detection device 3 is further configured to determine each of the voltages across the individual UV LEDs 2 as well as the currents flowing through them, if necessary by referring to information available to the control and regulation device. If a UV LED circuit is provided that includes several UV LEDs 2, the voltage drop and / or the current for the entire UV LED circuit can be measured.

[0045] If a malfunction occurs in one of the UV LEDs 2, for example, flickering, reduced luminous intensity, or complete failure of the UV LEDs 2, the detection device 3 recognizes this by the fact that a reduced or no current flows through the respective UV LED 2 and / or the voltage drop across the UV LED changes. Alternatively or additionally, the detection device 3 can be connected to the temperature sensors 5 and detect the malfunction by the measurement of a comparatively low temperature or a temperature change.

[0046] Furthermore, the detection device 3 can alternatively or additionally be configured to determine the intensity of the radiation emitted by the UV LEDs 2 and, if applicable, its wavelength or wavelength ranges, in addition to the current and / or voltage measurement and / or temperature measurement using the optical sensor.

[0047] The detection device 3 is configured such that, upon detecting a malfunction of the UV LEDs 2, the device 1 sends a signal to the control and / or regulating device 4, which then causes all UV LEDs 2 to be deactivated and, if necessary, additionally emits a warning signal indicating the malfunction, preferably optical, tactile, or acoustic. Furthermore, it may be designed to characterize the malfunction, for example, by displaying a code, the malfunction via the indicator LED 14, or another display device.

[0048] If the device 1 provides 2 different circuits for the UV LEDs and a malfunction is found in only one or simultaneously in individual circuits, all of the circuits for the UV LEDs 2 are switched in such a way that the UV LEDs 2 can no longer emit light.

[0049] Furthermore, if a malfunction is detected by the control and / or regulating device 4, the entire device 1 could be taken out of service.

[0050] Furthermore, an adjustment device 28 is formed on the circuit board 13 by the electronic components, which is intended to regulate the power with which the LEDs 2,6 emit light as a function of the temperature of the device 1, in order to compensate for changes in current strength that occur when the device 1 heats up, in order to regulate the respective intensities to the intended values.

[0051] A fan 16 is provided for cooling the device 1, by means of which air can be blown onto the circuit board 13 and the heat sink 11. The housing 9 is provided on its rear side with a ventilation grille 17, which is designed to hold a filter and through which air is drawn in by the fan 16.

[0052] The device 1 also has a handle 18, at the lower end of which a line 20 is guided via a strain relief 19, through which the device 1 can be supplied with energy and, if necessary, controlled.

[0053] How in particular Fig. 3 As can be seen, the device 1 is provided on its rear side with pushbuttons 21, 22, 23, 24 and a rotary control 25, which are intended for controlling intensities with which the LEDs 2, 6 light up and which interact with the control and / or regulating device 4.

Claims

1. Device for emitting electromagnetic radiation, in particular UV radiation, which has at least one radiation means (2), which is formed by at least one light-emitting diode (2) that only emits radiation at invisible wavelengths, wherein the device (1) comprises an apparatus (3) for identifying a malfunction of the light-emitting diode (2), characterized in that the device (1) is configured to automatically shut down the device (1) or at least the light-emitting diode (2) upon identification of the malfunction of the light-emitting diode (2) by the identifying apparatus (3).

2. Device according to Claim 1, characterized in that the radiation means (2) is provided for emitting only UV radiation, blue-violet radiation or / and IR radiation.

3. Device according to Claim 1 or 2, characterized in that the radiation means (2) is formed by multiple light-emitting diodes.

4. Device according to any one of Claims 1 to 3, characterized in that the identifying apparatus (3) is configured to continuously monitor the radiation means (2) for malfunctions.

5. Device according to any one of Claims 1 to 4, characterized in that the device (1) is intended to indicate that there is a malfunction.

6. Device according to any one of Claims 1 to 5, characterized in that the device comprises an apparatus (5) for measuring an electrical voltage dropping at the radiation means (2).

7. Device according to any one of Claims 1 to 6, characterized in that the measuring apparatus (5) is configured to measure an electrical current flowing through the radiation means (2).

8. Device according to any one of Claims 1 to 7, characterized in that the measuring apparatus (5) is configured to measure heat caused by the radiation means (2), to measure an intensity with which the radiation means (2) radiates, or / and to measure the wavelength or / and the wavelength range of the radiation emitted by the radiation means (2).

9. Device according to any one of Claims 1 to 8, characterized in that the device (1) comprises, in addition to the radiation means (2), an apparatus (6) for emitting visible light, preferably white light, wherein the device (1) is preferably configured to change an intensity with which the radiation means (2) radiates, regardless of an intensity with which the emitting apparatus (6) radiates.

10. Device according to any one of Claims 1 to 9, characterized in that the device is designed as a luminaire for inspecting workpiece surfaces, preferably for detecting contaminants, for penetrant testing and / or for fluorescent magnetic powder testing.

11. Method for operating a device for emitting electromagnetic radiation, in particular UV radiation, which has at least one radiation means (2), which is formed by at least one light-emitting diode that only emits radiation at invisible wavelengths, wherein the device (1) identifies a malfunction of the light-emitting diode (2) by means of an identifying apparatus (3), characterized in that the device (1) or at least the light-emitting diode (2) is automatically shut down when the malfunction is identified by the identifying apparatus (3).

12. Method according to Claim 11, characterized in that the device indicates the presence of a malfunction.

13. Use of the device according to any one of Claims 1 to 10 for, in particular visually, inspecting workpiece surfaces.

14. Use according to Claim 13, characterized in that the device is used for detecting contaminants, for penetrant testing and / or for fluorescent magnetic powder testing.