LIGHT AND METHOD FOR OPERATING A LIGHT

Abstract

A light, in particular for testing workpiece surfaces using a fluorescent marking device, which light has at least two lighting elements that emit electromagnetic radiation with different wavelength ranges. The intensity with which the lighting element irradiates can be adjusted separately for at least one of the lighting elements. Expediently, the light is configured to increase or reduce the intensity of at least one of the lighting elements and at the same time to keep the intensity of at least one other of the lighting elements constant, or to reduce it or increase it in the opposite way to the first-mentioned lighting element. The light is configured to adjust the intensity at such a speed that the human eye can adapt to a change in the intensity during the adjustment without adverse effects on the person's sight.

Claims

1-15. (canceled)

16. A luminaire for testing workpiece surfaces, comprising: at least two illuminants that emit electromagnetic radiation in different wavelength ranges, wherein an intensity with which each illuminant radiates is adjustable for at least one of the illuminants.

17. The luminaire according to claim 16, wherein the luminaire is configured to increase or to reduce the intensity of at least one first of the illuminants and simultaneously keep constant the intensity of at least one other of the illuminants or to reduce or increase the intensity oppositely to the first illuminant.

18. The luminaire according to claim 16, wherein the luminaire is configured so that a speed at which the intensity is adjusted is dependent on the intensity with which the respective illuminant radiates.

19. The luminaire according to claim 18, wherein at comparatively low intensity the speed is lower than at comparatively high intensity.

20. The luminaire according to claim 16, wherein the luminaire is configured for adjusting the intensity at a speed so that a human eye can adapt to a change in the intensity during the adjustment without impairment of visual perception.

21. The luminaire according to claim 16, wherein the luminaire is configured for adjusting the intensity so that a change in the intensity is perceived by the human eye as uniform without intensity jumps.

22. The luminaire according to claim 16, wherein a speed at which the intensity is changed is between 5 lux/s and 500 lux/s.

23. The luminaire according to claim 16, wherein one of the illuminants is configured to emit visible light and another of the illuminants is configured to emit ultraviolet radiation, infrared radiation and/or blue-violet light.

24. The luminaire according to claim 23, wherein the visible light is white light.

25. The luminaire according to claim 16, further comprising a control and/or regulation device for adjusting the intensities.

26. The luminaire according to claim 16, wherein the luminaire is configured for indicating an operating state of at least one of the illuminants.

27. The luminaire according to claim 26, wherein the operating state comprises the intensity with which the illuminant emits the radiation, and/or an emission duration.

28. The luminaire according to claim 27, wherein the emission duration is at a predetermined intensity.

29. The luminaire according to claim 16, comprising at least one operating device for changing the intensity.

30. The luminaire according to claim 29, wherein the operating device is a hand or foot operated switch and/or regulator.

31. The luminaire according to claim 16, further comprising a monitoring device configured to identify and indicate an operational fault.

32. The luminaire according to claim 31, wherein the monitoring device is configured to detect defects in the illuminants and to deactivate the luminaire upon identification of a fault.

33. A method for operating a luminaire for testing workpiece surfaces using a fluorescent marking medium, said luminaire comprising at least two illuminants which emit electromagnetic radiation in different wavelength ranges, the method comprising adjusting an intensity with which at least one of the illuminants radiate.

34. The method according to claim 33, including adjusting the intensity at a speed so that a human eye can adapt to a change in the intensity during the adjustment without impairment of the faculty of sight.

35. The method according to claim 33, wherein the lumainaire comprises an operating element, and the intensity with which a first one of the illuminants radiates is increased or reduced by actuation of the operating element and the intensity with which another illuminant radiates is simultaneously either kept constant or changed oppositely to the first illuminant.

Description

[0052] The invention is explained in greater detail below on the basis of an exemplary embodiment and the accompanying drawings relating to the exemplary embodiment, in which:

[0053] FIG. 1 shows a luminaire according to the invention in lateral section,

[0054] FIG. 2 shows a front view of the luminaire according to FIG. 1,

[0055] FIG. 3 shows a rear view of the luminaire according to FIG. 1, and

[0056] FIGS. 4 to 6 show diagrams elucidating the invention.

[0057] A luminaire 1 according to the invention as illustrated in FIGS. 1 to 3 comprises eight UV LEDs 2 provided for emitting UV radiation (wavelength range 200-400 nm) and eight white light LEDs 3 provided for emitting white light (wavelength range 380-780 nm). Optical components 4, 5 are arranged in front of the LEDs 2, 3 in order to influence respective beam paths emerging from the LEDs. A front screen 7 is arranged downstream of the optical components 4, 5 as viewed in the radiation direction, said front screen being connected to a housing 9 of the luminaire 1 via fixing means 10 and being provided with filters 8 for each of the UV LEDs 2.

[0058] The LEDs 2, 3 are soldered onto a carrier board 6 arranged on a heat sink 11. The heat sink 11 is connected via spacer bolts 12 to a printed circuit board 13 carrying a plurality of electronic components. Furthermore, an indicator LED 14 is arranged on the printed circuit board 13, said indicator LED being provided for indicating an operating state of the luminaire 1, as explained in greater detail below. An optical waveguide 15 is arranged between a rear side of the housing 9 and the indicator LED 14, by means of which optical waveguide radiation can be guided from the indicator LED 14 to the rear side.

[0059] The electronic components form a regulation and/or control device 26 configured for controlling and/or regulating the intensities with which the LEDs 2, 3 radiate.

[0060] The electronic components furthermore form a monitoring device 27 provided for identifying faults during the operation of the luminaires 1. The monitoring device 27 is connected in such a way that it can deactivate the luminaire 1 upon an operational fault being found, for example upon failure of one of the LEDs 2, 3. Furthermore, it can be provided, for example by indicating a code, for characterizing the operational fault via the indicator LED or some other indicator device.

[0061] Furthermore, an adjusting device 28 is formed by the electronic components on the printed circuit board 13, said adjusting device being provided for regulating powers with which the LEDs 2, 3 radiate depending on a temperature of the luminaire 1 in order to be able to compensate for a change in the current intensity that occurs upon heating of the luminaire 1, in order to regulate the respective intensities to the values provided.

[0062] A fan 16 is provided for cooling the luminaire, by means of which fan air can be blown onto the printed circuit board 13 and the heat sink 11. The housing 9 is provided on its rear side with a ventilation grille 17, which is provided for accommodating a filter and through which the air is drawn in by means of the fan 16.

[0063] The luminaire 1 furthermore comprises a handle 18, at the lower end of which a line 20 is led via a strain reliever 19, via which line the luminaire 1 can be supplied with energy and controlled, if appropriate.

[0064] As can be gathered from FIG. 3, in particular, the luminaire 1 is provided on its rear side with pushbuttons 21, 22, 23, 24 and a rotary regulator 25, which are provided for controlling intensities with which the LEDs 2, 3 emit light, and which interact with the control and/or regulation device 26.

[0065] The control and regulation device 26 is provided for varying intensities with which the UV LEDs 2 and the white light LEDs 3 radiate separately from one another by means of pulse width modulation.

[0066] The control and regulation device 26 changes the intensities at a speed such that the human eye can adapt to the changing intensity without or with only slight impairment of visual perception, in particular visual acuity, such that a defect found can be kept in view upon the change in the intensity. Furthermore, the intensities are changed in such a way that the human eye perceives the change in intensity uniformly, i.e. without intensity jumps. In order, on the one hand, to enable a changeover from an illumination with UV radiation to an illumination with white light in a manner that causes as little fatigue as possible and, on the other hand, to carry out the changeover of the last-mentioned prerequisite as rapidly as possible, the control and regulation device 26 is programmed in such a way that the respective intensity, in accordance with the adaptability of the human eye, is changed comparatively slowly at low intensity and more rapidly at comparatively high intensity. In this case, a speed at which the respective intensity is changed can be proportionally or exponentially dependent on the respective intensity or be changed linearly as a function of time.

[0067] Actuation of the pushbuttons 21, 22, 23, 24 causes the control and regulation device 26 to change the intensities of the UV LEDs and of the white light LEDs 3, as explained below with reference to FIGS. 4 to 6, which show diagrams illustrating the temporal profile of the intensities of the UV LEDs 2 (Y-axis I.sub.UV plotted on the left-hand side) and of the white light LEDs 3 (Y-axis I.sub.W plotted on the right-hand side).

1.SUP.ST .EXAMPLE (cf. FIG. 4)

[0068] At the point in time t.sub.1, the pushbutton 21 is actuated and, as a result, the UV LED 2 is switched on and emits light with a target intensity I.sub.MAX at which a workpiece can be examined.

[0069] At the point in time t.sub.2, actuation of one of the pushbuttons 22 causes fading across from radiation with the UV LED 2 to radiation by means of the white light LED 3, that is to say that the intensity with which the white light LED 3 radiates, as explained above, is increased to a target intensity I.sub.MAX and at the same time the intensity with which the UV LED 2 radiates is reduced to an extent such that it no longer radiates. At the point in time t.sub.3, the target intensity I.sub.MAX of the white light LED 3 is attained and the intensity of the UV LED is reduced to zero. The workpiece can then be inspected under white light.

[0070] If the intention is then to carry out a renewed examination also under UV illumination, the pushbutton 22 is released again, with fading across to illumination by means of the UV LED 2 (points in time t.sub.4 and t.sub.5), and renewed actuation of the pushbutton 22 makes it possible to fade across to white light again (points in time t.sub.6 and t.sub.7).

[0071] Upon renewed fading across to UV light, the pushbutton 22 is released again (points in time t.sub.8 and t.sub.9).

[0072] In order to switch off the UV LED 2, the pushbutton 21 is actuated again.

[0073] It goes without saying that fading across back and forth between the UV LED 2 and white light LED 3 can be effected as often as desired for examining the workpiece.

[0074] It may be provided that fading across to a radiation only by means of white light is carried out only as long as one of the pushbuttons 22 is actuated and, when one of the pushbuttons 22 is released, conversely, the intensity of the white light LED 3 is reduced again and that of the UV LED is increased to the target intensity.

[0075] Advantageously, a location on the workpiece, e.g. a defect observed under ultraviolet radiation or under white light, can be kept in view during fading-across as well. In both changeover directions, i.e. from white light to ultraviolet radiation and vice versa, the respective changes in intensity are perceived as a film. Since the changes in intensity are perceived at speeds such that the eyes can adapt thereto, visual perception, in particular visual acuity, is not impaired or is only slightly impaired.

[0076] As illustrated in FIG. 4a, the intensities of the UV LED 2 and of the white light LED 3 can be changed in such a way that the intensities are changed more rapidly at higher intensities than at low intensities. As explained above, the human eye can then adapt better to the changing intensities.

[0077] However, it would also be conceivable to change the intensities linearly as a function of time, as shown in FIG. 4b.

[0078] It goes without saying that the different for changing intensities could also be combined with one another. In this regard, it might be possible e.g. to change only the intensity of the white light LED 3 depending on the magnitude of the intensity and to change the intensity of the UV LED 2 proportionally to time.

2.SUP.ND .EXAMPLE (FIG. 5)

[0079] At a point in time t.sub.1, by means of the actuation of the pushbutton 21, the UV LED 2 is switched on and the intensity is set to the target intensity I.sub.MAX. By means of the actuation of one of the pushbuttons 23 (point in time t.sub.2), the white light LED 3 is set in addition to the UV LED 2, wherein the intensity with which the white light LEDs radiates, as explained above, is increased gradually to a target value I.sub.MAX until it attains the latter at a point in time t.sub.3, and the intensity with which the UV LED 2 emits light remains constant. In the same way as explained above, the intensity of the white light LED 3 is increased and the intensity is kept constant at I.sub.MAX only as long as the pushbutton 23 is kept pressed, and release (point in time t.sub.4) of the pushbutton 23 causes the intensity of the white light LED 3 to be reduced again until it no longer radiates from the point in time t.sub.5 on. Afterward, as necessary, the white light LED 3 can be switched again to the UV LED 2 (points in time t.sub.6 to t.sub.8 and t.sub.10). Once the examination of the workpiece has ended, the UV LED is switched off by the actuation of the pushbutton 21 (points in time t.sub.9 and t.sub.11).

[0080] As explained above with reference to FIG. 5, in this example as well the white light LED 3 can be varied at different speeds depending on the respective intensity (FIG. 5a) or the intensity can be implemented as a linear function of time (FIG. 5b).

3.SUP.RD .EXAMPLE (FIG. 6)

[0081] As shown in FIG. 6, the UV LED, after the switch-on of the white light LED 3, could also be switched off (points in time t.sub.4 and t.sub.5) and be switched on again as necessary again to the white light (points in time t.sub.6 and t.sub.7) for observing the workpiece under UV radiation, the intensity of the white light LEDs 3 is then reduced again (points in time t.sub.8 and t.sub.9).

[0082] Furthermore, FIG. 6 reveals that also when the UV LED 2 is switched on, the intensity can be increased to the target value I.sub.MAX gradually, e.g. at one of the speeds described above.

[0083] The pushbutton 24 is provided for maintaining respectively attained intensities of the UV LED 2 and of the white light LED 3, i.e. for preventing an illumination state attained with the luminaire 1 from being changed. By way of example, by means of the actuation of the pushbutton 24, the luminaire 1 can be kept in the state at the point in time t.sub.3 according to FIG. 4a or in the state following point in time t.sub.3 according to FIG. 5a, without the pushbutton 22 or the pushbutton 22 or 23 having to be kept pressed.

[0084] The rotary regulator 25 is provided for varying the target intensity with which the white light LED 3 radiates within certain predetermined limits and for setting it for work with the luminaire 1.