DE102019128320A1 - Motor vehicle lighting device for emitting a shielded light distribution - Google Patents

Abstract

The invention relates to a motor vehicle lighting device (2) for emitting a shielded light distribution (4) with a horizontal light-dark border (6). The shielded light distribution (4) comprises light of a first maximum illuminance below the light-dark boundary (6) and light of a second maximum illuminance in an overhead area (14) of the light distribution (4) above the light-dark boundary (6). In order to be able to reproduce objects (46) in the overhead area (14) particularly color-fast and with high color intensity, it is proposed that the lighting device (2) have at least one first light source (26) for emitting at least the light below the light-dark boundary (6) and at least has a further light source (38) for emitting at least part of the light of the overhead area (14), wherein the at least one further light source (38) is designed to emit light that is an object ( 46) reproduces a selected color with a better color rendering Ri according to CRI 1976 than would be possible with light from the at least one first light source. In particular, it is proposed that the at least one further light source (38) is designed to emit light which has a color rendering index Ra according to CRI 1976 of Ra> 80.

Description

The present invention relates to a motor vehicle lighting device, in particular a motor vehicle headlight, for emitting a shielded light distribution with a horizontal light-dark boundary. The shielded light distribution comprises light of a first maximum illuminance below the light-dark boundary and light of a second maximum illuminance in an overhead area of the light distribution above the light-dark boundary.

A shielded light distribution is, for example, low beam or fog light. In the case of low beam in particular, the light distribution emitted includes not only the light below the light-dark boundary, but also a small amount of light above the light-dark boundary to illuminate the so-called overhead area and the traffic signs, sign gantries or other objects located there. The second maximum illuminance of the light in the overhead area is smaller than the first maximum illuminance of the light below the light-dark boundary.

According to the relevant ECE regulation No. 112 for dipped headlights, a maximum illuminance of 0.4 lux is permissible in the overhead area at a point B50L for right-hand traffic and B50R for left-hand traffic on a measuring screen at a distance of 25 m from the headlight. The point B50L is located 1,500 mm to the left of a vertical plane v-v on the measuring screen and 250 mm above a horizontal plane h-h on the measuring screen, with a focal axis of the headlamp running through the intersection HV of the two planes v-v and h-h. At the same time, according to ECE R112 in the overhead area, the sum of the illuminance in three points 1 (-3,500 mm / +1,750 mm), 2 (0 / +1,750 mm) and 3 (+3,500 mm / +1,750 mm) must be at least 0.3 lux and in three other points 4 (-1,750 mm / +875 mm), 5 (0 / +875 mm) and 6 (+1,750 mm / +875 mm) are at least 0.6 lux. The coordinates of the points are each related to the intersection point HV. This means that minimum values for illuminance are also prescribed for the overhead area.

The overhead area is usually also illuminated by light from at least one light source to generate the shielded light distribution below the light-dark boundary. To illuminate the overhead area, either scattered light from the light source is used or light from the light source is specifically directed into the overhead area. Furthermore, headlights are known from the prior art that have an additional light source for illuminating the overhead area (e.g. DE 10 2013 207 850 A1 ).

Newer headlights in particular have standard light sources (e.g. LEDs, high-power LEDs or laser diodes) which, at least for objects of certain colors, only have an inadequate color rendering Ri according to CRI 1976. The spectrum of such standard light sources has only a low intensity in the corresponding wavelength ranges. The color rendering index Ra = 1/1 x sum (Ri) with i = 1 ... 1 and I corresponding to the number of colors i whose color rendering Ri is considered is in a range of only Ra = 60 for such standard light sources. 70, with 100 being the maximum. As a result, illuminated objects are only reproduced with insufficient color fastness and appear pale. This applies in particular to objects of one color that are underrepresented in the spectrum of the standard light sources mentioned (e.g. blue-green in the range from approx. 470 nm - 530 nm or red in the range from approx. 600 nm - 800 nm). This means that, for example, motorway signs in blue (in Germany, France) or green (in Italy, Switzerland, the USA) are only displayed in a pale blue or pale green and thus for the driver of a motor vehicle are very difficult to see.

Finally from the DE 10 2013 001 259 A1 a motor vehicle headlight is known in which the additional light source for illuminating the overhead area emits light of a selected color in order to improve the contrast of traffic signs located in the overhead area. For example, it is proposed to illuminate a traffic sign with white text on a blue background with yellow light. As a result, the background of the traffic sign appears black, so that the white writing stands out in a particularly high-contrast. In a corresponding manner, it is proposed, for example, to illuminate a traffic sign with white writing on a green background with magenta light, so that the background of the traffic sign appears black and the white writing is particularly contrasting.

Through the in the DE 10 2013 001 259 A1 However, the proposed colored illumination of the overhead area falsifies the color of the traffic sign or its background. This results in a synthetic impression which can irritate a driver of a motor vehicle that is equipped with the headlights described. When looking for a motorway information sign, for example, the driver expects a traffic sign with a blue or green background; in fact, he is only presented with traffic signs with a black background. Despite the improved contrast of the illuminated traffic signs, it is therefore very difficult for the driver to recognize the traffic signs. The subjective expectation of the Driver on a traffic sign of a certain background color is in contradiction to the objectively perceived color of the traffic sign. This increases the stress for the driver, which can ultimately lead to distraction, inattention and danger to other road users.

Based on the described prior art, the present invention is based on the object of designing and developing a motor vehicle lighting device, in particular a motor vehicle headlight, in such a way that it provides illumination of the overhead area, which realizes a particularly true-to-color color rendering of the illuminated objects.

To solve this problem, a motor vehicle lighting device having the features of claim 1 is proposed. In particular, based on the motor vehicle lighting device of the type mentioned at the beginning, it is proposed that the lighting device have at least one first light source for emitting at least the light below the light-dark boundary, as well as at least one further light source for emitting at least part of the light of the overhead area, the at least one further light source is designed to emit light that renders an object of a selected color located in the overhead area of the light distribution with a better color rendering Ri according to CRI 1976 than would be possible with light from the at least one first light source.

In particular, the invention proposes that the at least one further light source, which illuminates the overhead area, uses the light it emits to compensate for the deficits of the at least one first light source in terms of color rendering, i.e. the inadequate rendering of objects in their actual color. As a result, objects in the overhead area of the light distribution are reproduced on the one hand in their actual color and on the other hand with high color saturation. In this way, the driver of a motor vehicle that is equipped with the lighting device according to the invention can recognize traffic signs more quickly and detect them more reliably. This is beneficial to road safety.

In contrast to the prior art, where the aim is to improve the contrast in the overhead area, the invention is about an improvement in color reproduction and color saturation. This is expressed by the color rendering Ri or the color rendering index Ra, which is significantly higher than the corresponding size of the light emitted by the at least one first light source to generate the shielded light distribution below the light-dark boundary.

Contrast is the difference between the lightest and darkest visible tone value. In contrast, the color rendering is a quality feature of artificial light compared to natural sunlight, how colors are rendered by illuminated objects. A light source whose light contains all the colors of the spectrum - like sunlight - makes the colors of the illuminated objects look natural - the color rendering is optimal. However, modern LEDs, high-performance LEDs and laser diodes do not reproduce all spectral colors equally well. Therefore, the invention proposes to supplement the illumination in the overhead area with light from an additional light source or to realize which objects of selected colors can reproduce better than the light from the first light source, which emits the light for the dimmed light distribution of the headlamp.

Light sources with particularly good color rendering, which can be used, for example, as the at least one additional light source for illuminating the overhead area, often have only a relatively low luminous flux. However, this is not critical when illuminating the overhead area, since no high illuminance values are required there.

• #1 Altrosa
• #2 Senfgelb
• #3 Gelbgrün
• #4 Hellgrün
• #5 Türkisblau
• #6 Himmelblau
• #7 Asterviolett
• #8 Fliederviolett
• #9 Rot gesättigt
• #10 Gelb gesättigt
• #11 Grün gesättigt
• #12 Blau gesättigt
• #13 Rosa (Hautfarbe)
• #14 Blattgrün

To determine the color rendering index, 14 reference colors were specified in accordance with DIN 6169. The following are intended as reference colors:

• # 1 dusty pink
• # 2 mustard yellow
• # 3 yellow green
• # 4 light green
• # 5 turquoise blue
• # 6 sky blue
• # 7 aster violet
• # 8 Lilac purple
• # 9 Red saturated
• # 10 Saturated yellow
• # 11 Green saturated
• # 12 Saturated blue
• # 13 pink (skin color)
• # 14 leaf green

For these reference colors, the secondary spectra are measured with a reference light source (eg sunlight) and a test light source (eg the first or further light source). The Deviations result in 14 reference values (Ri). In order to determine the general color rendering index Ra, the arithmetic mean of the first eight indices i = 1 ... 8 is determined. So you add up the eight numerical values Ri and divide the result by eight. Further reference values can be specified, for example R9 for saturated red.

The number of reference colors included in the Ra color rendering index was initially increased to 14 and later to 15. The more colors are included in the calculation of the Ra index, the more precisely it describes the quality of the light. Since an average is determined from the various Ri values, even a high-quality light source can have weaknesses in the reproduction of individual colors. In the present invention, the at least one further light source is designed in such a way that it compensates for the weaknesses in the color rendering of the at least one first light source.

The at least one first light source for emitting light is advantageously designed exclusively below the light-dark boundary. The overhead area is therefore only illuminated by light from the at least one further light source. Of course, it would also be conceivable that part of the light emitted by the at least one first light source (e.g. scattered light or specifically deflected light) reaches the overhead area. The color rendering in the overhead area would then result from a superposition of the light component of the at least one first light source and the light of the at least one further light source.

In a corresponding manner, it can be provided that the at least one further light source is designed to emit light exclusively into the overhead area. The area of the light distribution below the light-dark boundary is therefore only illuminated by light from the at least one first light source. Of course, it would also be conceivable that a small part of the light emitted by the at least one further light source (e.g. scattered light) also reaches the area below the light-dark boundary. However, since the intensity of the light from the at least one further light source is relatively low, in any case significantly lower than the intensity of the light from the at least one first light source below the light-dark boundary, the (possibly colored) light from the at least one further light source would not disturb the shielded light distribution or affect.

According to an advantageous development of the invention, it is proposed that the at least one further light source is designed to emit light whose color rendering value Ri for the at least one selected color of the object according to CRI 1976 Ri> 80. The light emitted by the at least one further light source should, for example, compensate for the low intensity of the light from the at least one first light source in a wavelength range of approximately 470 nm - 530 nm (blue-green) and / or 600 nm - 800 nm (red), so that blue or green motorway signs or red warning / prohibition or other red signs are reproduced in a better color, in particular more saturated in color. This can be achieved in that the at least one further light source is designed to emit light mainly in a spectral range from 470 nm to 530 nm and / or from 600 nm to 800 nm. “Mainly” in this context means that the spectrum of the at least one further light source in one or the mentioned wavelength ranges has a significantly greater intensity than the spectrum of the at least one first light source of conventional design.

When driving on German or French motorways, the light emitted by the at least one additional light source could be set so that it reproduces objects in blue color (e.g. blue motorway signs) in a better color. If, on the other hand, you are driving on Italian or Swiss motorways, the light emitted by the at least one additional light source could be set in such a way that it, for example, reproduces objects in green color (e.g. green motorway signs) in a better color. An adaptation of the light emitted by the at least one further light source with a view to improved color rendering of objects of a specific color can take place, for example, as a function of position information from a navigation system of the motor vehicle. The adaptation can even go so far that a distinction is made between whether the motor vehicle is traveling on a motorway or on a country road or in a town. On country roads in Germany, for example, the light emitted by the at least one further light source could be set in such a way that it reproduces objects in yellow color (e.g. yellow country road signs and signs at town entrances) in a better color. Within built-up areas, for example, the light emitted by the at least one additional light source could be set in such a way that it reproduces objects in red color (e.g. stop signs, right of way signs and red borders of prohibition signs) in a better color.

In particular, it is proposed that the at least one further light source is designed to emit light that reproduces an object of a saturated red color located in the overhead area of the light distribution with a color rendering according to CRI 1976 of R9> 80. This will make objects in red color particularly well, ie particularly realistically, reproduced.

It is further proposed that the at least one further light source is designed to emit light that reproduces an object of a saturated yellow color located in the overhead area of the light distribution with a color rendering according to CRI 1976 of R10> 80. As a result, objects in yellow are reproduced particularly well, i.e. particularly realistically.

It is further proposed that the at least one further light source is designed to emit light that reproduces an object of a saturated green color located in the overhead area of the light distribution with a color rendering according to CRI 1976 of R11> 80. As a result, objects in green are reproduced particularly well, i.e. particularly realistically.

Finally, it is proposed that the at least one further light source is designed to emit light that reproduces an object of a saturated blue color located in the overhead area of the light distribution with a color rendering according to CRI 1976 of R12> 80. As a result, objects in blue are reproduced particularly well, i.e. particularly realistically.

It is of course conceivable that the at least one further light source is designed to emit light that meets the requirements for several of the reference values mentioned R9 ... R12 fulfilled.

Alternatively or additionally, it is proposed that the at least one further light source is designed to emit light that has a color rendering index Ra according to CRI 1976 of Ra> 80. The color rendering index is also known as the Color Rendering Index (CRI). The color rendering index Ra is the arithmetic mean of the first eight indices i = 1 ... 8 or the first 14 indices i = 1 ... 14 or even the first 15 indices i = 1 ... 15 of the reference values Ri for the various reference colors .

According to an advantageous development of the invention, it is proposed that the at least one further light source comprises an RGB-LED, the spectrum of which is set so that the light emitted by the RGB-LED is an object of a selected color with a better color rendering located in the overhead area of the light distribution Ri according to CRI 1976 reproduces as that would be possible with light from the at least one first light source. An RGB LED is a combination of three LEDs with different colors, a red LED, a green LED and a blue LED, which are arranged in a common housing. An RGB LED can output different colors by mixing the three basic colors red, green and blue and changing the intensity if necessary. The light spectrum emitted by the RGB-LED can be adapted by suitable control of the three colored LEDs so that the emitted light has a high intensity, especially in the wavelength range where the spectrum of the at least one first light source for generating the shielded light distribution has a deficit.

According to a preferred embodiment of the present invention, it is proposed that the or each first light source is designed as an LED or a laser diode for emitting white light with the aid of a conversion material. Such light sources first emit blue or UV light that hits a conversion material (e.g. phosphor), which converts part of the incident light into yellow light. A superposition of the unconverted blue and the converted yellow light results in the desired white light. However, this has only a relatively low intensity in a spectral range of blue-green (approx. 470 nm - 530 nm) and in another spectral range of red (approx. 600 nm - 800 nm), so that one through the at least one Light emitted by the first light source - if it reaches the overhead area - illuminated blue, green or red object is only reproduced in an inadequate (not very realistic, little color intensive, e.g. pale) color. The present invention is intended to compensate for this.

In this sense, it is proposed that the at least one further light source is designed to emit light in a spectral range from 470 nm - 530 nm and / or from 600 nm - 800 nm with a higher intensity than a conventional LED (e.g. the at least one first light source ) can. The intensity of the light is therefore particularly high in one or both of the specified spectral ranges, so that the deficits of the light emitted by the at least one first light source can be compensated for.

• 1 eine schematische Schnittansicht durch eine erfindungsgemäße Kraftfahrzeugbeleuchtungseinrichtung;
• 2 Verteilungen der relativen Intensität einer herkömmlichen LED und einer Lichtquelle mit einem hohen Farbwiedergabeindex Ra;
• 3 ein Beispiel für eine Verkehrssituation im Vorfeld eines Kraftfahrzeugs mit Verkehrszeichen im Overheadbereich einer abgeblendeten Lichtverteilung;
• 4 eine abgeblendete Lichtverteilung auf einem in einem Abstand vor der Kraftfahrzeugbeleuchtungseinrichtung angeordneten senkrechten Messschirm gemäß der ECE R112; und
• 5 Messpunkte oberhalb der Horizontalebene h-h auf einem in einem Abstand vor der Kraftfahrzeugbeleuchtungseinrichtung angeordneten senkrechten Messschirm gemäß der ECE R112.

Further features and advantages of the present invention are explained in more detail below with reference to the figures. Individual features of the exemplary embodiments can also be relevant to the invention individually or can be combined with one another in any combination, even if this combination is not expressly shown and / or described. Show it:

• 1 a schematic sectional view through a motor vehicle lighting device according to the invention;
• 2 Distributions of the relative intensity of a conventional LED and a light source with a high color rendering index Ra;
• 3 an example of a traffic situation in front of a motor vehicle with traffic signs in the overhead area of a dimmed light distribution;
• 4th a shielded light distribution on a vertical measuring screen arranged at a distance in front of the motor vehicle lighting device in accordance with ECE R112; and
• 5 Measuring points above the horizontal plane hh on a vertical measuring screen arranged at a distance in front of the motor vehicle lighting device in accordance with ECE R112.

The present invention relates to a motor vehicle lighting device, in particular a motor vehicle headlight which is shown in FIG 1 shown in a schematic sectional view and in its entirety with the reference number 2 is designated. The headlight is to emit a shielded light distribution (cf. 4th ) with a horizontal light-dark border 6th educated. The dimmed light distribution 4th includes light of a first maximum illuminance below the light-dark boundary 6th and light of a second maximum illuminance in an overhead area of the light distribution 4th above the light-dark border 6th .

A dimmed light distribution 4th is, for example, dipped headlights or fog lights or a part of them. 4th shows a dimmed light distribution 4th using the example of a low beam distribution on a measuring screen arranged at a distance of 25 m in front of the motor vehicle or the motor vehicle lighting device 8th that is perpendicular to an optical axis 10 of the headlight 2 is arranged according to the annex 3 the ECE R112, for right-hand traffic. On the measurement screen 8th a horizontal plane hh and a vertical plane vv are recorded. An intersection HV of the two planes runs through the optical axis 10 . The light distribution is for left-hand traffic 4th mirrored at the vertical plane vv, a relevant measuring point in the overhead area is no longer B50L, but B50R. The invention is described below on the basis of right-hand traffic, but the explanations also apply in a corresponding manner to left-hand traffic.

The low beam 4th in 4th is designed as a so-called asymmetrical low beam with a first horizontal section 6a the light-dark border 6th on the opposite side of the traffic and a second section rising obliquely upwards (for example at an angle of 45 °) from the vertical plane vv 6b on your own traffic page. The ascending section 6b can be in another section 6c on your own traffic side, which increases with a smaller increase, or in a horizontal section 6c ' that is above the horizontal section 6a runs, which is arranged on the opposite side of the traffic. Especially with the low beam 4th the emitted light distribution does not only include the light in one area 12th below the chiaroscuro line 6th , but also a small amount of light above the light-dark boundary 6th to illuminate the so-called overhead area 14th and traffic signs, sign gantries or other objects from there.

5 shows different measuring points above the horizontal plane hh for a low beam distribution 4th on the measurement screen 8th according to ECE R112 for right-hand traffic. The measuring points are for left-hand traffic 7th and 8th mirrored at the vertical plane vv. According to the ECE R112 is on the measuring screen 8th at one point B50L for right-hand traffic and B50R for left-hand traffic in the overhead area 14th a maximum illuminance of 0.4 lux is permitted. The point B50L is located 1,500 mm to the left of the vertical plane vv and 250 mm above the horizontal plane hh. At the same time, in accordance with ECE R112 in the overhead area (cf. 5 ) the sum of the illuminance in three points 1 (-3,500 mm / +1,750 mm), 2 (0 / +1,750 mm) and 3 (+3,500 mm / +1,750 mm) at least 0.3 lux and in three other points 4th (-1,750 mm / +875 mm), 5 (0 / +875 mm) and 6 (+1,750 mm / +875 mm) are at least 0.6 lux. The coordinates of the points are each related to the intersection point HV. So are for the overhead area 14th minimum values for illuminance are also prescribed.

The headlight 2 is designed for installation in a corresponding installation opening on the front of a motor vehicle. The headlight 2 includes a housing 16 , which is preferably made of plastic. In one light exit direction 18th has the housing 16 a light exit opening 20th on that through a transparent cover panel 22nd is locked. This is preferably made of plastic or glass. It can be designed with or without optically effective elements (for example prisms or cylindrical lenses) for scattering the light passing through. Inside the case 16 is a headlight module 24 arranged.

The headlight module 24 serves to generate the dimmed light distribution 4th . To this end, the module 24 at least one first light source 26th which, for example, comprises a semiconductor light source, in particular a light-emitting diode (LED), preferably a high-power LED, or a laser diode. The or each first light source 26th is preferably designed as an LED or a laser diode for emitting white light with the aid of a conversion material. The module also has 24 via a bundling or primary optics 28 , which for example. A reflector and / or - as in 1 may include a lens (so-called attachment optics). The module 24 can be used as a reflection module or - as in 1 shown - be designed as a projection module.

To create the light-dark border 6th the dimmed light distribution 4th has the headlight module 24 out 1 via an aperture 30th that have a vertical or - as in 1 shown - may have a horizontal extent. One edge 32 the aperture 30th - in the example 1 a leading edge 32 the aperture 30th - is through a projection or secondary optics 34 to create the light-dark border 6th pictured in front of the vehicle. A light distribution in an intermediate image plane 36 of the headlight module 24 is through the projection optics 34 to generate the shielded light distribution 4th pictured in front of the vehicle. The image is preferably reversed (light above the optical axis 10 becomes below the light-dark boundary 6th and light to the right or left of a vertical plane through the optical axis 10 becomes left or right in the light distribution 4th pictured. The projection optics 34 can be used as a reflector or - as in 1 shown - be designed as a projection lens. A focal point or a focal point cloud of the projection optics 34 lies on or near the intermediate level 36 .

The headlight module also includes 24 at least one other light source 38 which is below a horizontal plane through the optical axis 10 is arranged. From the at least one further light source 38 emitted light is through the projection optics 34 in the overhead area 14th the dimmed light distribution 4th above the light-dark border 6th projected. The at least one other light source 38 can - provided it emits light of a predetermined wavelength spectrum - be designed in any way. It preferably comprises a semiconductor light source, in particular an LED with a specific color rendering value for specific colors and / or a specific color rendering index (so-called CRI value). It would also be conceivable that the light source 38 comprises an RGB-LED, each having at least one LED for emitting red, yellow and blue light, the RGB-LEDs being integrated in a common LED housing.

The overhead area 14th the dimmed light distribution 4th can by light from the at least one first light source 26th to generate the shielded light distribution 4th below the chiaroscuro line 6th be illuminated with. This can be used to illuminate the overhead area 14th either scattered light from the light source 26th can be used or part of the light from the light source is targeted 26th in the overhead area 14th steered. In the present invention, the at least one further light source is 38 provided to the overhead area 14th additionally to be illuminated.

Especially headlights 2 newer designs have standard light sources 26th (e.g. LEDs, high-power LEDs or laser diodes) at least for objects 46 Certain colors in front of the motor vehicle show insufficient color rendering Ri according to CRI 1976. The spectrum 40 such standard light sources 26th (see. 2 ) points in corresponding wavelength ranges 42 , 44 only a low intensity. The color rendering index Ra = 1/1 x sum (Ri) with i = 1 ... 1 and I corresponding to the number of colors i, whose color rendering Ri is considered, is found in such standard light sources 26th in a range of only Ra = 60-70, with 100 being the maximum. This leads to lighted objects 46 (see. 3 ) can only be reproduced with insufficient color fastness and consequently appear pale. This particularly applies to objects 46 a color that is in the spectrum 40 of the standard light sources mentioned 26th are underrepresented (e.g. blue-green in the area 42 from approx. 470 nm - 530 nm or red in the range 44 from approx. 600 nm - 800 nm). So if such conventional light sources 26th to illuminate the overhead area 14th are used, this leads to the fact that, for example, motorway signs 46 in blue (in Germany, France) or green (in Italy, Switzerland, the USA) are only shown in a pale blue or a pale green and are therefore very difficult to recognize for the driver of a motor vehicle. This also applies to headlights 2 in which the at least one additional light source 38 to illuminate the overhead area 14th is designed as such a standard semiconductor light source.

It is therefore proposed according to the invention that the at least one further light source 38 is designed to emit light, the one in the overhead area 14th the light distribution 4th located object 46 (see. 3 ) reproduces a selected color with a better color rendering Ri according to CRI 1976 than that with light from the at least one first light source 26th it is possible.

The at least one other light source 38 , which is the overhead area 14th illuminates, the deficits of the at least one first light source can with the light emitted by it 26th in color rendering, i.e. the inadequate rendering of objects 46 in their actual color. This creates objects 46 in the overhead area 14th the light distribution 4th on the one hand in their actual color and on the other hand with higher Color saturation reproduced. In this way, the driver of a motor vehicle that is equipped with the lighting device according to the invention 2 is equipped, road signs 46 Recognize faster and record more reliably what is very beneficial to road safety.

Unlike in the prior art, where there is an improvement in the contrast in the overhead area 14th what is sought is a rendering of the color of objects 46 can result in a wrong color or with low color saturation, the aim of the invention is to improve the color reproduction and color saturation, in particular to reproduce the objects with strong colors in their actual color. This is expressed by the color rendering Ri or the color rendering index Ra for the at least one additional light source 38 is significantly higher than the corresponding size of the at least one first light source 26th to generate the shielded light distribution 14th below the chiaroscuro line 6th emitted light.

To determine the color rendering index Ra, according to DIN 6169 14th Reference colors set. The number of reference colors can also be selected to be smaller (eg eight reference colors) or larger (eg 15 reference colors). For these reference colors, the secondary spectra are measured with a reference light source (eg sunlight) and a test light source (eg the first or further light source). The deviations result in 14 reference values Ri. In order to determine the general color rendering index Ra (so-called CRI value), the arithmetic mean of the first eight indices i = 1 ... 8 is determined. So you add up the eight numerical values Ri and divide the result by eight. Information on further discrete reference values is possible, for example R9 for saturated red. It is also conceivable to determine the color rendering index Ra on the basis of the arithmetic mean of another number of reference values Ri, e.g. on the basis of the first 14 or the first 15 reference values Ri. Je The more colors are included in the calculation of the Ra index, the more precisely it describes the quality of the light.

The at least one first light source is advantageous 26th to emit light only into the area 12th below the chiaroscuro line 6th educated. The overhead area 14th is therefore only from light from the at least one additional light source 38 illuminated. Of course, however, it would also be conceivable that part of the from the at least one first light source 26th emitted light (e.g. scattered light or deliberately deflected light) into the overhead area 14th got. The color rendering in the overhead area 14th would then result from a superposition of the light component of the at least one first light source 26th and the light of the at least one further light source 38 .

In a corresponding manner, it can be provided that the at least one further light source 38 for emitting light exclusively into the overhead area 14th is trained. The area 12th the light distribution 4th below the chiaroscuro line 6th is therefore only from light from the at least one first light source 26th illuminated. Of course, it would also be conceivable that part of the at least one further light source 38 emitted light (e.g. scattered light) also into the area 12th below the chiaroscuro line 6th got. Because the intensity of the light from the at least one additional light source 38 is relatively low, in any case significantly lower, than the intensity of the light from the at least one first light source 26th below the chiaroscuro line 6th , would be the (possibly colored) light from at least one other light source 38 the dimmed light distribution 4th do not disturb or impair.

The at least one other light source 38 can be optimized with regard to the color rendering value Ri for one or more colors and / or with regard to the color rendering index Ra (CRI value). In this sense, it is proposed that the at least one further light source 38 is designed to emit light whose color rendering value Ri for the at least one selected color of the object according to CRI 1976 Ri> 80. That of the at least one other light source 38 Emitted light should, for example, have the low intensity of the light from the at least one first light source 26th in a wavelength range 42 from around 470 nm - 530 nm (blue-green) compensate for blue or green motorway signs 46 can be reproduced better in terms of color, in particular more true-to-color and more saturated in color.

If you prefer to drive on German or French motorways, this could be from the at least one additional light source 38 emitted light can be adjusted so that there are, for example, objects 46 in blue color (e.g. blue motorway signs) better in terms of color. If, on the other hand, you are driving on Italian, Swiss or US motorways, this could come from at least one other light source 38 emitted light can be adjusted so that there are, for example, objects 46 in green color (e.g. green motorway signs) better in terms of color. An adaptation of the at least one further light source 38 emitted light with a view to improved color rendering of objects 46 a specific color can, for example, take place as a function of position information from a navigation system of the motor vehicle. The adaptation can even go so far that a distinction is made between whether the motor vehicle is on a motorway or drives on a country road or in a town. On country roads in Germany, for example, this could be from the at least one additional light source 38 emitted light can be adjusted so that there are objects 46 in yellow color (e.g. yellow country road signs and signs at the entrance to the town) better in color. Within built-up areas, for example, the light emitted by the at least one further light source could be adjusted in such a way that it objects 46 in red color (e.g. stop signs, right-of-way signs and red borders around prohibition signs).

In particular, it is proposed that the at least one further light source 38 is designed to emit light, the one in the overhead area 14th the light distribution 4th located object 46 a saturated red color with a color rendering according to CRI 1976 of R9> 80. This creates objects 46 reproduced particularly well in red, ie particularly realistically. Alternatively or additionally, it is proposed that the at least one further light source 38 is designed to emit light, the one in the overhead area 14th the light distribution 4th located object 46 a saturated yellow color with a color rendering according to CRI 1976 of R10> 80. This creates objects 46 reproduced particularly well in yellow, ie particularly realistically. Furthermore, it is alternatively or additionally proposed that the at least one further light source 38 is designed to emit light, the one in the overhead area 14th the light distribution 4th located object 46 a saturated green color with a color rendering according to CRI 1976 of R11> 80. This creates objects 46 reproduced particularly well in green, ie particularly realistically. Finally, it is alternatively or additionally proposed that the at least one further light source 38 is designed to emit light, the one in the overhead area 14th the light distribution 4th located object 46 a saturated blue color with a color rendering according to CRI 1976 of R12> 80. This creates objects 46 reproduced particularly well in blue, ie particularly realistically.

The at least one other light source 38 is designed to emit light that meets the requirements for only one or more of the mentioned reference values R9 .. R12 fulfilled.

Alternatively or additionally, it is proposed that the at least one further light source 38 is designed to emit light which has a color rendering index Ra according to CRI 1976 of Ra> 80. The color rendering index Ra is the arithmetic mean of the first eight indices i = 1 ... 8 or the first 14 indices i = 1 ... 14 or even the first 15 indices i = 1 ... 15 of the reference values Ri for the various reference colors . The spectrum of such a further light source 38 is e.g. in 2 shown and with the reference number 48 designated.

If the at least one more light source 38 comprises an RGB-LED, its spectrum is preferably set so that that of the RGB-LED 38 emitted light in the overhead area 14th the light distribution 4th located object 46 a selected color with a better color rendering Ri according to CRI 1976 than that with light from the at least one first light source 26th it is possible. One RGB LED 38 can output different colors by mixing the three basic colors red, green and blue and changing the intensity if necessary. That from the RGB-LED 38 The light spectrum output can be adjusted by suitable control of the three colored LEDs so that the light emitted is particularly in the wavelength range 42 , 44 has a high intensity where the spectrum 40 the at least one first light source 26th to generate the shielded light distribution 14th has a deficit. The spectrum of the at least one further light source 38 would then be roughly the range 40 a conventional LED 26th correspond with the exception that the relative intensity in the areas 42 , 44 would be significantly higher, in particular> 0.3, preferably> 0.4, particularly preferably> 0.5, very particularly preferably> 0.6.

The at least one further light source is very particularly preferred 38 formed light in a spectral range 42 from 470 nm - 530 nm and / or in a spectral range 44 to emit from 600 nm - 800 nm with higher intensity than a conventional LED 26th (see the spectrum 40 in 2 ) can. The intensity of the light is therefore in one or both of the specified spectral ranges 42 , 44 particularly high, so that the deficits of the at least one first light source 26th emitted light can be compensated.

When the intensity values of light in the overhead area 14th already in part by the at least one first light source 26th operated, as in the example of the 1 by branched off light from the light source 26th (cf. the light beam drawn in as an example 50 ), is at least one other light source 38 sufficient which only in the areas 42 , 44 the gaps in the spectrum 40 the standard LED 40 fills, so which is essentially light in the spectral range 42 at approx. 470 nm - 530 nm and in the spectral range 44 emits at approx. 600 nm - 800 nm, possibly also with several color chips (RGB-LED) The overall color and the CRI value in the overhead area 14th the light distribution 4th then result from the superposition of the two light sources 26th , 38 .

When the intensity values of light in the overhead area 14th solely through the at least one additional light source 38 operated is an LED 38 preferred, which has a high CRI value. In this case too, an RGB LED with a corresponding spectrum of the individual color chips can be used as at least one additional light source 38 can be used.

Especially when using an RGB LED as at least one additional light source 38 with individually controllable chips, the color spectrum in the overhead area 14th can be adapted to the driving situation. Information about the driving situation can include position data / map data, camera data from an onboard camera or a navigation system. For example, when driving towards a motorway in Germany or France, the color spectrum can be in the overhead area 14th to be shifted to the bluish to the highway signs 46 especially highlighted in color. When driving towards a motorway in Italy, Switzerland or the USA (cf. 3 ) the color spectrum in the overhead area 14th to be shifted to the greenish to the highway signs 46 especially highlighted in color.

Because of the abundance of signs, a very high level of attention and an overview is required for a driver. If, for example, a route to Los Angeles via the freeway were planned in the navigation system, it would be advantageous to focus on the spectrum 48 the intensity values in the overhead area 14th in the greenish spectral range 42 (approx. 490 nm - 560 nm) to place the appropriate signs 46 to be particularly easily recognizable.

Furthermore, it would be conceivable to additionally reduce the proportion from other spectral ranges, for example in the in 3 shown example to reduce the bluish area (approx. 450 nm - 490 nm). Blue signs are displayed less intensely and paler in color. This enables the driver to perceive the important green signs 46 can be further improved, so that they are thus preferably recognized by the driver

It would also be conceivable to use several RGB LEDs as additional light sources 38 to use and a matrix RGB overhead light 14th to create. This means that different parts of the overhead area can be used if necessary 14th be illuminated with different spectra, e.g. to cut out a traffic light.

In particular, it is also conceivable to use the at least one further light source for the color spectrum in the high beam case 38 to enrich. Because of the - compared to the light for generating the high beam - the low intensity of the light of the at least one further light source 38 however, this effect is relatively small. In this case it would be advantageous to have several other light sources 38 , preferably to be used with optics that work dimmed in the low beam and undimmed in the high beam. So the enrichment effect of the spectrum above the light-dark border can 6th can be improved in the high beam case.

It is also conceivable to use the overhead light distribution 14th to switch temporarily completely to a certain color or a color range, e.g. to switch completely to blue. This is particularly advantageous in the event that game was detected on the road or at the edge of the road in front of the vehicle. Wild particularly reacts to light from the blue color spectrum with flight.

In summary, the present invention thus proposes a headlight 2 before that has improved visibility of objects 46 in the overhead area 14th disposes. The improved visibility of colored objects 46 , such as traffic signs, can be achieved by using at least one additional light source 38 with a high color rendering index Ra (CRI value). LEDs with high luminous flux, such as those for the at least one first light source, for example 26th are used to generate the low beam, generally have a smaller CRI value than LEDs with a low luminous flux, as they are for the at least one additional light source 38 can be used. For lighting the overhead area 14th only a small luminous flux is necessary.

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102013207850 A1 [0004]
• DE 102013001259 A1 [0006, 0007]

Claims (12)

Motor vehicle lighting device (2) for emitting a shielded light distribution (4) with a horizontal light-dark boundary (6), the shielded light distribution (4) being light of a first maximum illuminance below the light-dark boundary (6) and light of a second maximum illuminance in an overhead area (14) the light distribution (4) above the light-dark boundary (6), characterized in that the lighting device (2) comprises at least one first light source (26) for emitting at least the light below the light-dark boundary (6), as well as at least one further light source (38) for Emitting at least part of the light of the overhead area (14), wherein the at least one further light source (38) is designed to emit light that an object (46) located in the overhead area (14) of the light distribution (4) of a selected color with a better color rendering Ri according to CRI 1976 than that with light of min at least a first light source would be possible. Motor vehicle lighting device (2) according to Claim 1 , characterized in that the at least one first light source (26) is designed to emit light exclusively below the light-dark boundary (6). Motor vehicle lighting device (2) according to Claim 1 or 2 , characterized in that the at least one further light source (38) is designed to emit light exclusively into the overhead area (14). Motor vehicle lighting device (2) according to one of the preceding claims, characterized in that the at least one further light source (38) is designed to emit light whose color rendering value Ri for the selected color of the object according to CRI 1976 Ri> 80. Motor vehicle lighting device (2) according to one of the preceding claims, characterized in that the at least one further light source (38) is designed to emit light which an object (46) located in the overhead area (14) of the light distribution (4) has a saturated red color a color rendering according to CRI 1976 of R9> 80. Motor vehicle lighting device (2) according to one of the preceding claims, characterized in that the at least one further light source (38) is designed to emit light which an object (46) located in the overhead area (14) of the light distribution (4) has a saturated yellow color a color rendering according to CRI 1976 of R10> 80. Motor vehicle lighting device (2) according to one of the preceding claims, characterized in that the at least one further light source (38) is designed to emit light that an object (46) located in the overhead area (14) of the light distribution (4) has a saturated green color a color rendering according to CRI 1976 of R11> 80. Motor vehicle lighting device (2) according to one of the preceding claims, characterized in that the at least one further light source (38) is designed to emit light which an object (46) located in the overhead area (14) of the light distribution (4) has a saturated blue color a color rendering according to CRI 1976 of R12> 80. Motor vehicle lighting device (2) according to one of the preceding claims, characterized in that the at least one further light source (38) is designed to emit light which has a color rendering index Ra according to CRI 1976 of Ra> 80. Motor vehicle lighting device (2) according to one of the preceding claims, characterized in that the at least one further light source (38) comprises an RGB-LED, the spectrum (48) of which is set so that the light emitted by the RGB-LED is in the overhead area ( 14) of the light distribution (4) located object (46) of a selected color with better color rendering Ri according to CRI 1976 than would be possible with light from the at least one first light source (26). Motor vehicle lighting device (2) according to one of the preceding claims, characterized in that the or each first light source (26) is designed as an LED or a laser diode for emitting white light with the aid of a conversion material. Motor vehicle lighting device (2) according to one of the preceding claims, characterized in that the at least one further light source (38) is designed to emit light mainly in a spectral range from 470 nm to 530 nm and / or from 600 nm to 800 nm.

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