DAYLIGHT HAND-LAMP FOR CHECKING PAINTED SURFACES, IN PARTICULAR IN THE FIELD OF PAINT REPAIR WORK ON MOTOR VEHICLES

Abstract

A daylight hand-lamp for checking painted surfaces, in particular in the field of paint repair work on motor vehicles. The light spectrum is formed homogenously such that at a distance of between 30 cm0.5 cm in a spectral range having a wavelength of 400 to 700 nm, a daylight deviation average value in a central area and an inner periphery is less than 20%, or the average value of a spectral stability factor is less than 10% with respect to the beam center in the central area and inner periphery.

Claims

1. A daylight hand-lamp for examining painted surfaces, the daylight hand-lamp comprising a light-emitting body, by way of which a light beam is generable, wherein the light beam forms a beam cross-sectional area which extends perpendicularly to a beam axis at a distance of 30 cm0.5 cm from the light-emitting body along the beam axis, wherein the beam cross-sectional area has at least one central core region with an inside diameter of at least 16 cm, wherein the light at least in the core region has a general color rendition index with a value of greater than 95, wherein the illuminance in the entire core region is greater than 5000 lx, wherein the beam cross-sectional area additionally has an inner peripheral region surrounding the core region, wherein the illuminance in the inner peripheral region decreases to at least 1000 lx, and wherein the light spectrum across the beam cross-sectional area is homogeneous at least such that, in a spectral range with a wavelength of 400 to 700 nm, a daylight deviation mean at least in the core and inner peripheral regions is less than 20%, and/or that, in a spectral range with a wavelength of 400 to 700 nm, the mean of a spectral stability factor with respect to the beam center at least in the core and inner peripheral regions is less than 10%.

2. The daylight hand-lamp of claim 1, wherein the calculation of the daylight deviation mean of a location of the beam cross-sectional area is performed such that a light spectrum that is normalized to the maximum intensity is ascertained at this location, the difference of the ascertained light spectrum with respect to a daylight spectrum that is normalized to the maximum intensity is formed, and subsequently the mean of the absolute differences over the spectral range of 400 to 700 nm is formed.

3. The daylight hand-lamp of claim 1, wherein the calculation of the mean of the spectral stability value with respect to the beam center of a location of the beam cross-sectional area is performed such that a light spectrum that is normalized to the maximum intensity is ascertained at that location, the difference of the ascertained light spectrum with respect to a light spectrum, which is normalized to the maximum intensity and was ascertained in the beam center, is formed, and subsequently the mean of the absolute differences over the spectral range of 400 to 700 nm is formed.

4. The daylight hand-lamp of claim 1, wherein the core region has an inside diameter of at least 20 cm.

5. The daylight hand-lamp of claim 1, wherein the illuminance in the core region is greater than 6000 lx.

6. The daylight hand-lamp of claim 1, wherein the daylight deviation mean in the core and inner peripheral regions is less than 18%.

7. The daylight hand-lamp of claim 1, wherein the daylight deviation mean in the core region and inner peripheral region changes by less than 6%.

8. The daylight hand-lamp of claim 1, wherein the mean of the spectral stability factor with respect to the beam center in the core and inner peripheral regions is less than 8%.

9. The daylight hand-lamp of claim 1, wherein the illuminance in the inner peripheral region decreases to 500 lx.

10. The daylight hand-lamp of claim 1, wherein the inner peripheral region is ring-shaped.

11. The daylight hand-lamp of claim 1, wherein the inner peripheral region has a width of greater than 4 cm.

12. The daylight hand-lamp of claim 1, wherein the color temperature at least in the core and inner peripheral regions is greater than 5500 K and/or less than 6500 K.

13. The daylight hand-lamp of claim 1, wherein the light-emitting body has at least one halogen lamp.

14. The daylight hand-lamp of claim 1, wherein the light-emitting body comprises one or more light-emitting diodes.

15. The daylight hand-lamp of claim 1, wherein the light-emitting body comprises a plurality of light-emitting diodes, wherein the plurality of light-emitting diodes emit light with the same light spectrum.

16. The daylight hand-lamp of claim 1, wherein the light-emitting body comprises one or more COB light-emitting diodes.

17. The daylight hand-lamp of claim 1, wherein the light-emitting body comprises one or more light-emitting diodes having a color-imparting luminescence material.

18. The daylight hand-lamp of claim 1, wherein the light-emitting body comprises a plurality of light-emitting diodes, wherein for forming the light spectrum at least one light-emitting diode is provided, which emits light with a light spectrum that differs from the light spectrum of another light-emitting diode.

19. The daylight hand-lamp of claim 1, wherein the light-emitting body comprises a plurality of light-emitting diodes, wherein the light-emitting diodes are each provided with a lens.

20. The daylight hand-lamp of claim 1, wherein the light-emitting body comprises a plurality of light-emitting diodes, wherein the plurality of light-emitting diodes are arranged in a plane, with at least some of the plurality arranged with equal distribution on an outer circular orbit and at least some of the plurality arranged with equal distribution on an inner circular orbit.

21. The daylight hand-lamp of claim 1, wherein the daylight hand-lamp is embodied in the form of a cable-free hand-lamp operated with a battery.

22. The daylight hand-lamp of claim 1, wherein the luminous intensity of the light beam which is generable by the light-emitting body is settable.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0043] Further refinements of the invention are the subject matter of the dependent claims and of the exemplary embodiments of the invention described below. The invention will be explained in more detail below in the form of exemplary embodiments with reference to the attached figures, in which specifically:

[0044] FIG. 1 shows a side view of a daylight hand-lamp including a schematic illustration of the generable light beam,

[0045] FIG. 2 shows the beam cross-sectional area of the light beam in accordance with FIG. 1 in a schematic illustration,

[0046] FIG. 3 shows a schematic illustration of the measurement apparatus for measuring the light beam of a daylight hand-lamp,

[0047] FIG. 4 shows the illuminance of the daylight hand-lamp in accordance with FIG. 1 as a function of the distance DM from the beam center,

[0048] FIG. 5 shows the illuminance in dependence on the distance rM from the beam center in accordance with FIG. 4 only in the outer distance region,

[0049] FIG. 6 shows a comparison of the normalized light spectrum of the daylight and the normalized light spectrum of the daylight hand-lamp in accordance with FIG. 1,

[0050] FIG. 7 shows the difference of the normalized light spectra from FIG. 6,

[0051] FIG. 8 shows the daylight deviation mean of the daylight hand-lamp in accordance with FIG. 1 as a function of the distance rM from the beam center in percent,

[0052] FIG. 9 shows the mean of the spectral stability factor of the daylight hand-lamp in accordance with FIG. 1 as a function of the distance rM from the beam center in percent, and

[0053] FIG. 10 shows a front view of the head part of the daylight hand-lamp in accordance with FIG. 1.

DETAILED DESCRIPTION

[0054] FIG. 1 shows a daylight hand-lamp 1 for checking painted surfaces, in particular as part of paint repair work on motor vehicles. The hand-lamp 1 has a head part 2, a handle part 3 and, at the lower end of the handle part 3, a releasably attached battery 4, in particular a lithium ion battery. The head part 2 has, on its front side, a light exit opening 5, through which a light beam 6 can exit. A light-emitting body 7 is arranged in the head part 2 for generating the light beam 6. FIG. 1 shows the head part 2 in the region of the light exit opening 5 in partial section so as to illustrate at least part of the light-emitting body 7.

[0055] An operating element 8, by way of which the luminous intensity of the generated light beam 6 is settable for example in a range from 50 to 100% of the maximum luminous intensity, is provided on the rear side of the head part 2. A further operating element 9 for switching the hand-lamp 1 on and off is arranged on the side facing away from the operating element 8 and below the head part 2.

[0056] FIG. 1 furthermore schematically illustrates the light beam 6 which is generable by the hand-lamp 1 and propagates along a beam axis 10. The light beam 6 forms a beam cross-sectional area 11 extending perpendicularly to the beam axis 10 at a distance d of 30 cm0.5 cm from the light-emitting body 7. The distance is measured from the outer surface of the last optical element of the light-emitting body 7 through which the light beam 6 travels before it leaves the hand-lamp 2. In the present case, this optical element is a thin cover plate of the light-emitting body 7.

[0057] FIG. 2 shows the circular beam cross-sectional area 11 in plan view. The beam cross-sectional area 11, or the light properties thereof, correspond to the properties of a reference light spot, which is formed using the hand-lamp 1 on a planar surface when the light-emitting body 7 of the hand-lamp 1 is held at a distance of 30 cm above the surface and the light beam 6 is directed perpendicularly onto the surface.

[0058] The beam cross-sectional area 11 and the reference light spot can be divided into three regions. Starting from the beam center 12, the beam cross-sectional area 11 has a central circular core region 13, a ring-shaped inner peripheral region 14, and a ring-shaped outer peripheral region 15. The regions 13, 14, 15 are not shown strictly to scale in FIG. 2.

[0059] The central core region 13 has, for example, an inside diameter of at least 16 cm. The light at least in the core region 13 has a general color rendition index value (CRI value) of greater than 95. The illuminance in the entire core region 13 is greater than 5000 lx.

[0060] In an example of a definition of the regions, the core region 13 transitions into the inner peripheral region 14 when the illuminance falls below the value of 5000 lx. The inner peripheral region 14 in turn transitions into the very low-light outer peripheral region 15 when the illuminance has decreased to at least 1000 lx.

[0061] The color temperature of the light beam 6 is greater than 5500 K, at least in the core and inner peripheral region 13, 14.

[0062] The light generated by the hand-lamp 1 is characterized in that it is, at least in the core and inner peripheral regions 13, 14, homogeneous with respect to the light spectrum. This is clear from the fact that, in a spectral range with a wavelength of 400 to 700 nm, a daylight deviation mean in the core and inner peripheral regions 13, 14 is less than 20%.

[0063] In addition, the mean of a spectral stability factor with respect to the beam center in the core and inner peripheral regions 13, 14 is also less than 10% in the spectral range with a wavelength of 400 to 700 nm.

[0064] What follows is a description of how the light beam 6 of the hand-lamp 1 is measured and how finally the daylight deviation mean (FIG. 7) and the mean of the spectral stability factor with respect to the beam center 12 (FIG. 8) are ascertained from the measurement results.

[0065] FIG. 3 illustrates by way of example a measurement apparatus 20, by way of which the light properties of the hand-lamp 1 can be determined. The hand-lamp 1 is preferably attached to a stand 22 at a distance d of 30 cm above a detector 21 (specifically the lens of the detector).

[0066] The detector 21 used was a checked and calibrated spectrometer MK350S by UPRtek, having a linear CMOS image sensor (spectral bandwidth: approximately 12 nm (half bandwidth), receptor size: diameter 6.6 mm +/0.1 mm, measurement range: 20-70 000 lx, wavelength range: 380-780 nm, integration time: 6-5000 ms).

[0067] The receptor or the measurement field of the detector 21 is shown in FIG. 3 by way of example in two positions. In the first position, the receptor is arranged centralized with respect to the center 12 of the light beam 6. In this position, the light properties in the beam center 12 are subsequently ascertained. Next, the detector 21 is radially shifted outwardly by 2 cm on the planar support surface 23. The light properties of this location of the beam cross-sectional area or of the reference light spot are ascertained. This procedure continues in 2-cm steps until a distance r.sub.M of 24 cm from the center is reached, i.e., a location is measured which is situated on a circular orbit around the center 12 having a diameter of 48 cm. FIG. 3 shows, as the second position of the detector 21, a position having a distance r.sub.M of 24 cm from the beam center 12 by way of example.

[0068] All measurements were performed under uniform conditions in a darkened space. The hand-lamp 1 was switched off in each case between the measurements to prevent measurement distortions caused by different switching times.

[0069] FIGS. 4 and 5 show the illuminance thus ascertained as a function of the distance r.sub.M of the measurement location from the beam center 12 (r.sub.M=0 cm). It is apparent that the illuminance continuously decreases outwardly from the beam center 12. It is advantageous for checking painted surfaces that the illuminance decreases gradually rather than abruptly.

[0070] It should be noted that the illuminance for a hand-lamp having light-emitting diodes as light-emitting means fades particularly gently in the peripheral region. Such gentle fading can also be obtained, for example, using a halogen lamp. However, the light of the halogen lamp in known lamps in turn has the disadvantage that the peripheral region has a different light spectrum (e.g., having a red cast). This colored corona has a disturbing effect when examining painted surfaces.

[0071] It is furthermore apparent that the illuminance in the example of the hand-lamp 1 decreases to below 5000 lx only at a distance r.sub.M of approximately 12 cm. Consequently, for a definition of the core region 13 in which an illuminance of greater than 5000 lx prevails in the entire core region 13, this gives a core region 13 having an inside diameter of approximately 24 cm.

[0072] In another approach or definition of the core region 13, it can be seen from FIG. 4 that, in the example of a hand-lamp, the illuminance in a core region 13 having a diameter of 16 cm (r.sub.M=8 cm) is even greater than 10 000 lx.

[0073] The hand-lamp 1 advantageously has a maximum illuminancein the beam center 12of more than 16 000 lx, specifically of more than 20 000 lx.

[0074] FIGS. 4 and 5 furthermore show that, for a definition in which the inner peripheral region 14 ends when the illuminance falls below 1000 lx, the inner peripheral region 14 ends at a distance rm from the beam center 12 of approximately 17 cm.

[0075] However, it is also possible to use definitions in which the inner peripheral region 14 is the region in which the illuminance decreases to 500 lx, preferably to 300 lx. In this case, the inner peripheral region 14 extends up to a distance rm of approximately 19 cm or 21 cm. Consequently, the inner peripheral region 14 can have a width of greater than 4 cm, preferably greater than 6 cm, with more preference greater than 8 cm.

[0076] To determine the daylight spectrum, measurements of the daylight were performed using the detector MK350S by UPRtek under different weather conditions, times of day and compass directions, and a daylight spectrum which is averaged over these measurements was calculated. The daylight spectrum thus calculated was compared to the values of the standard illuminant of the class D (daylight), in particular D65 (6500 K), of the CIE 1931 color space. Only slight deviations were ascertained which have no relevant influence on the parameters that are calculated on the basis of the daylight spectrum.

[0077] FIG. 6 shows the light spectra of the daylight and of the light beam of the hand-lamp in the beam center 12, which are respectively normalized to their maximum intensity. A good match with the daylight spectrum is apparent, which also becomes clear from the diagram shown in FIG. 7. FIG. 7 shows the difference in percent of the normalized spectra shown in FIG. 6 in the relevant range from 400 to 700 nm.

[0078] The mean over the range from 400 to 700 nm was formed based on the absolute differences shown. The result is thus the daylight deviation mean of the light beam 6 in the beam center 12 in percent. Analogously, the daylight deviation mean of the light beam 6 is ascertained in the case of the remaining measured distances rm from the beam center 12. The result can be found in FIG. 8, which shows the daylight deviation mean as a function of the distance r.sub.M.

[0079] The daylight deviation mean over the entire measured distance region is less than 20%, specifically even less than 18%. Up to a distance r.sub.M of approximately 22 cm, the daylight deviation mean is less than 16%.

[0080] In addition, the daylight deviation mean in the entire measured distance region varies by less than 6%, specifically by less than 4%.

[0081] As already mentioned, FIG. 9 shows the mean of a spectral stability factor with respect to the beam center 12. The spectral stability factor is determined analogously with the daylight deviation mean, but it is not the difference with respect to the normalized daylight spectrum but rather the difference with respect to the normalized light spectrum in the beam center 12 that is formed. Consequently, the mean of the spectral stability factor in the center 12 (distance r.sub.M=0 cm) is zero.

[0082] The mean of the spectral stability factor with respect to the beam center 12 is less than 8% up to a distance r.sub.M of approximately 20 cm, less than 6% up to a distance r.sub.M of approximately 14 cm.

[0083] Overall, the diagrams of FIGS. 8 and 9 show the high degree and the particular extent of the beam homogeneity of the light beam 6 generated by the hand-lamp 1.

[0084] To generate the homogeneous light beam 6, the light-emitting body 7 has a plurality of light-emitting diodes as light-emitting means which each emit light with the same light spectrum. For example, these can be COB light-emitting diodes. However, other types are also conceivable. The light-emitting diodes preferably have a color-imparting luminescence material, e.g., a phosphor-based color-imparting luminescence material.

[0085] FIG. 10 shows a front view of the head part 2 of the hand-lamp 1. The front end side of the light-emitting body 7 with the light-emitting diodes 24, which are each provided with a lens, is easily visible. The light-emitting diodes 24 are arranged in a plane. Nine light-emitting diodes 24 are arranged with equal distribution on an outer circular orbit 25. Three light-emitting diodes 24 are arranged with equal distribution on an inner circular orbit 26. Owing to this arrangement of the light-emitting diodes 24, a uniform intensity distribution of the generated light beam 6 is obtained.

[0086] For example, a common lens for all light-emitting diodes can also be used instead of individual lenses for each light-emitting diode. However, it is also conceivable to use in part individual lenses and in part one lens for a plurality of light-emitting diodes.

[0087] It is to be understood that a preferred exemplary embodiment of the invention has been described merely by way of example with reference to the figures. Other designs, in particular of the light-emitting body 7, which meet the requirements of the light properties according to the invention are conceivable and are apparent for a person skilled in the art upon reading of the above statements.

[0088] It should be mentioned by way of example that a light-emitting body may be provided which, in addition to a cover plate, also has one or more further optical elements (color filters, stops, lenses), which are preferably interchangeable. The optical effects, however, can also be realized by a cover plate which additionally serves to protect the head interior.

[0089] In the case of one application, which is not shown, the hand-lamp can also be used as a stationary illumination means. For example, the hand-lamp can be attached to a stand, a holder on the paint booth ceiling or wall, a post, a handling apparatus (robot), or a similar attachment system. Instead of using an energy supply using a battery, the hand-lamp can also be connected to the power grid by way of an adapter which is connected to the hand-lamp, for example, in place of the battery.

[0090] Generally, the hand-lamp can also be connected to a control system with cables or without (e.g., via Bluetooth). The control system can be used to switch the hand-lamp on and off, for example, or to set the luminous intensity. In this case, the actuation of the on/off switch and of the setting device for the luminous intensity can be effected by remote control using suitable apparatuses. The on/off switch can also remain in the set position (on or off), wherein the luminous intensity can be regulated or controlled remotely from 0% to 100%.

[0091] It is likewise possible for sensors (e.g., color, surface or distance sensors) to be present. The settings of the hand-lamp are performed or regulated (e.g., luminous intensity depending on distance) based on the measurement data of the sensors.

[0092] A separate control system can also provide suggestions, e.g., for using color filters or other optical elements, for the luminous intensity etc., with which the hand-lamp should be provided or set to attain optimum examination results. This suggestion can also be made based on sensor data, e.g. a color detection, gloss level detection, distance detection, or surface roughness detection of the painted surface.