DE102016207748A1 - Lighting device for a vehicle headlight, vehicle headlight and method for controlling a lighting device - Google Patents

Abstract

Disclosed is a lighting device or a light module for a headlamp with a radiation source that emits light radiation. In the case of light radiation, a light color can be set in particular as a function of a sensor which determines a degree of mesopic and scotopic vision.

Description

The invention relates to a lighting device for a (vehicle) headlamp with at least one radiation source arrangement, via which a light radiation can be emitted. Furthermore, the invention relates to a vehicle headlight with such a lighting device and a method for controlling the lighting device.

document US 2006 0044 818 A1 discloses a headlamp for a vehicle. In this, a hue can be adjusted depending on the environment, the position of the vehicle, the time and the date to improve the visibility of the vehicle for other road users. For this purpose, the headlight has three light sources to emit light radiation with different shades.

Furthermore, it is known that the human eye has on its retina photosensitive cells in the form of rods and cones. The cones have three different cone types with absorption maxima at wavelengths of about 420nm, 535nm and 570nm, which correspond to the colors blue-violet, emerald-green and yellow. The cones or receptors with the absorption maxima at about 420nm thus cover a blue region of a visible color spectrum. The sticks are responsible for a black and white dark vision. A maximum of a brightness sensitivity of the rods lies in the brightly adapted eye (photopic area), ie the eye, which is adapted to a brightness, at a wavelength of 555 nm. For the dark adapted eye (scotopic area), ie an eye adapted to a dark, there is a maximum at a well length of about 507nm. The shift of the maximum is also called "Purkinje effect". The eye adapts to the light-dark vision by means of an enlargement or reduction of the iris. An adaptation time required for the eye to become accustomed to darkness (transition to rodent vision) is about five to ten minutes, accompanied by a shift in color sensitivity of the eye to blue-green (wavelength of about 510 nm) to 507nm). Thus, in the scotopic area, a light output of the eye in the blue area or blue-green area is highest. In the brightly adapted eye in the photopic range, the light output is again highest at a wavelength of about 555 nm. Furthermore, it is known that younger persons, especially adolescents, have a higher spectral sensitivity in the blue range due to less yellowing of their eye lens, the sensitivity being about a factor of 8 higher than compared to a person of about 75 years.

The object of the present invention is to provide a lighting device for a headlamp and a vehicle headlamp, with or with the safety is increased. Furthermore, it is the object of the invention to provide a method for controlling a lighting device with which a safety in traffic can be increased in a simple manner.

This object is achieved with regard to the lighting device according to the features of claim 1, with regard to the vehicle headlight according to the features of claim 11 and with respect to the method according to the features of claim 12.

Particularly advantageous embodiments can be found in the dependent claims.

According to the invention, a lighting device is provided for a headlight or vehicle headlight. This has a radiation source arrangement with at least one radiation source, via which a light radiation can be emitted. Advantageously, the light color, in particular the blue light component of at least a subset of a total emission of the light radiation, in particular via a control unit, is adjustable or controllable.

This solution has the advantage that, if necessary, the light color of the radiation source arrangement is adjustable, and thus, for example, in the dark or twilight simply a blue light component or a blue-green component is increased.

Preferably, a sensor is provided, via which a degree of mesopic and / or scotopic and / or photopic vision can be determined, for example, via the measurement of the ambient brightness, wherein the adjustment of the light color takes place as a function of a sensor signal of the sensor. Thus, the control unit with its adaptation function or its blue adjustment function can take into account the values determined by the sensor.

In photopic vision or daytime vision or cones vision, a person's ability to see at sufficient brightness is understood. Under scotopic vision or night vision or chopstick vision, the ability of a human to see at low brightness is understood. Between photopic and scotopic vision, there is a transitional area, the mesopic area, or twilight vision. In the human eye, the cones of the retina are intended for photopic vision, and the light-sensitive rods of the retina for the scotopic vision. In the mesopic area, both cones and rods contribute to vision. As the rods are more sensitive to the short-wave color stimulus As the cones, they give a different impression of the brightness of different shades than the cones. It changes the color perception, which is noticeable especially at dusk, as soon as the dark adaptation begins. Especially blues appear much more brilliant in twilight vision. The sensor thus allows a precise adaptation of the light device to the human eye, whereby the security is increased.

In other words, a light module for a headlight is disclosed, which determines the degree of mesopic and / or scotopic vision by means of a sensor or sensors, and then shifts the light color of at least one subset into the shorter wave wave as needed.

In a further advantageous embodiment of the invention, the adjustment of the light color in dependence on a speed of the light device using vehicle takes place. Especially at higher speeds, it is important to be seen in time by other road users and to reliably estimate the speed of an approaching vehicle that is coming in or following. In particular, a blue tint at twilight and at night arouses increased attention and a better awareness of a fast approaching vehicle. An increasing proportion of blue light or blue-green at higher speeds thus ensures a better awareness or for a better "awareness" of other road users, whereby the own and foreign traffic safety is increased. Thus, a speed-adapted blue tint of the headlight is achieved in a simple manner. At twilight or at night, this visual effect (color shift) can be very pronounced, since the mesopically or scotopically adapted eye has a higher spectral sensitivity in the blue or blue-green wavelength range, which has already been explained above.

Preferably, with increasing speed, the light color is adjusted in the direction of shorter-wave light radiation or in the direction of blue or in the direction of blue-green or in the direction of an increase in the blue light component or blue-green light component. Furthermore, the light color is preferably adjusted with decreasing speed in the direction of longer-wave light radiation or in the direction away from blue or blue-green or in the direction of a reduction of the blue light component or blue-green light component. Thus, the speed adjustment takes place in the form that the faster the vehicle moves, the more a shift to the blue takes place.

Preferably, a shift in the light color of the light radiation is a color sum of the light radiation in the white field, which is specified by the Economic Commission for Europe (ECE) or a prescribed standard. Thus, despite changing the light color, the prescribed standard can be fulfilled by leaving the resulting light color within the ECE white field. For example, the resulting light color may be in a respective angular range of the total emission and / or in a predetermined range of the total emission and / or with an integral color location and / or in the entire angular field in the prescribed ECE field or ECE white field. It is not necessary, for example, that every area of the total radiation or every "point" must lie in the ECE white field, but, for example, only the integral color location must be "white", with which the light color can be defined via the emission angle. Thus, it is conceivable that different regions of the emitted light, for example in the edge region or in the periphery, can also lie outside the white field and thus have, for example, a higher proportion of blue light.

In a further embodiment of the invention, the shift of the light color or the adjustment function is linear or non-linear. If it is non-linear, it may, for example, be stepped or free-shaped or have a logarithmic or exponential course. Thus, preferably, a spectral shift of the light radiation with the speed is linear or non-linear. The adaptation function can also be time-dependent, whereby time functions can also be individualized.

The adaptation of the light color or the adjustment function of the light color are preferably dependent on an illumination function, such as dipped or high beam or daytime running lights. For example, in high beam the blue shift can be performed faster. Alternatively or additionally, the adaptation or the adaptation function can be dependent on times of day. Thus, for example, at night driving depending on the lighting function (low beam, high beam), the adjustment function of the blue shift can be set differently. Even with day trips can be increased in the daytime running lights and / or in the low beam, the blue component with increasing speed, for example, linear or non-linear.

The sensor explained above is preferably a sensor set for an eye sensitivity. For example, the sensor is designed as a photodiode. Alternatively, the sensor may correspond to a sensor used in a video camera, such as a CCD chip. The sensor set to the eye sensitivity can determine the degree of the mesopic or scotopic part. The mesopic vision starts at a luminance below about 30 cd / m ² , in particular below 3 cd / m ² . A luminance at night driving is approximately in the range of 0.1 cd / m ² , especially at reduced lighting conditions, such as when driving on a country road.

Alternatively or in addition to the described sensor, a sensor for detecting a steering angle of the vehicle may be provided, wherein the light color, in particular via the adjustment function, is adjustable as a function of the steering angle. This is extremely advantageous if, for example, a light pattern is used which is rather warm white in the field of vision or in the central region and is designed to be bluish or cool white in the outside, this division being couplable to the steering angle. Thus, for example, when steering the outside area, in particular in the direction in which is steered, reduced and the central area be increased accordingly.

In a further embodiment of the invention, the adjustment of the light color, in particular of the blue component, takes place only in certain angular ranges or emission ranges of the light radiation. Thus, for example, the proportion of blue in the edge area or outside area can be increased, so that the visibility for other road users is improved, while the central area remains unchanged in color, for example. This can be helpful, in particular in poor visibility conditions, especially in bad weather, since in such cases a yellower or warmer light color in the central region leads to an improved, in particular improved, vision.

The adaptation is advantageously carried out in such a way or the adaptation function is configured such that a speed of the setting of the light color is adapted to an adaptation curve of the human eye.

Furthermore, it is conceivable that the setting of the light color is dependent on the location of the light device. Thus, for example, the regulation may be formed differently in a city traffic than in the extra-urban traffic or on a highway. The location of the light device can preferably be determined via a corresponding sensor, for example via a GPS sensor.

In a further embodiment of the invention, the adaptation of the light color is such or the adjustment function is such that when using the light device in a vehicle in a reverse drive, when the light device in the front of the vehicle emits the light radiation, the blue light component is increased, so this one assumes bluish color. This provides better visibility for other road users. It is conceivable that the total light radiation during a reverse drive - that is, integral - blue, while in a forward drive, only the outer area appears bluish, by only in this area, the proportion of blue light is increased.

It is also conceivable, as an alternative or in addition to the control of the blue light component, to provide the control via the adaptation function also for other colors, such as red or green, with which the red light component and / or the green light component can be controlled.

In a preferred embodiment, the radiation source arrangement has at least one radiation source, such as an LED, in particular for an illumination function. For setting the light color, the radiation source arrangement then additionally has at least one further radiation source in the form of a blue radiation source, in particular a blue LED, which is controllable independently of the at least one radiation source which is used in particular for the illumination function.

A light emitting diode (LED) or light emitting diode may be in the form of at least one individually packaged LED or in the form of at least one LED chip having one or more light emitting diodes. Multiple LED chips may be mounted on a common substrate ("submount") and form an LED or may be mounted individually or collectively on, for example, a circuit board (e.g., FR4, metal core board, etc.) ("CoB" = chip on board). The at least one LED can be equipped with at least one own and / or common optics for beam guidance, for example with at least one Fresnel lens or a collimator. Instead of or in addition to inorganic LEDs, for example based on InGaN or AlInGaP, it is generally also possible to use organic LEDs (OLEDs, for example polymer OLEDs). The LED chips can be directly emitting or have an upstream phosphor. Alternatively, the LED may be a laser diode or a laser diode array.

The radiation sources or LEDs of the radiation source arrangement are preferably arranged on a common board. It may alternatively or additionally be provided a common optics for mixing the light emitted by the radiation sources.

It is also conceivable, alternatively or in addition to the blue radiation source or blue LED radiation sources or LEDs with different white variants, which have a different color temperature or a different color location to provide. Thus, for example, by switching or controlling these radiation sources the light color can be adjusted.

Preferably, the radiation sources are individual components. For example, these may be configured as packaged LEDs for, for example, an SMD assembly.

In a further preferred embodiment, radiation sources of the radiation source arrangement can be provided in red, green and blue (RGB). In order to increase the proportion of blue or blue-green, in this case a yellow mixture can be reduced and / or a blue mixture can be increased and, conversely, to reduce the proportion of blue or blue-green, the yellow mixture can be increased and / or the blue mixture can be lowered.

Alternatively or additionally, it can be provided that the adjustment of the light color or color shift by a pulse width modulation (PWM) or by a DC control or regulation of the current level of the radiation source arrangement, which in this case in particular one or more white light emitting LED chips, takes place.

Alternatively or additionally, it can be provided that the radiation source arrangement has at least one radiation source emitting an excitation radiation, which is followed by a conversion element arrangement, which may then be the laser-activated remote phosphor (LARP) technology. The conversion element arrangement advantageously has at least two different conversion elements, which can be introduced alternately or overlapping into a beam path of the excitation radiation. Alternatively or additionally, the conversion element arrangement can have at least one conversion element with at least two regions with different properties, wherein by displacement and / or rotation and / or tilting and / or rotation of this conversion element and / or steering of the excitation radiation, preferably one of the regions in each case Beam path of the excitation radiation can be introduced. As a result, the light color can be easily adapted by different conversion elements and / or by a conversion element with different conversion ranges.

For example, the light color can be adjusted by a thickness of the conversion element and / or by the proportion of cerium doping. Thus, a thinner conversion element for a higher proportion of blue and / or a lower cerium doping for a lower yellow conversion radiation and thus a higher proportion of blue can be provided. The conversion elements of the conversion element arrangement are preferably arranged approximately on a common radius of a rotatable device (phosphor wheel). An axis of rotation of the rotatable device is, for example, at a parallel distance from the light axis of the excitation radiation. The change of the conversion elements or remote converter can be done by rotating the device. Alternatively or additionally, it is conceivable that the conversion elements are arranged in series or the conversion element with the different properties on a laterally, in particular transversely to the beam path of the excitation radiation, displaceable device.

In general, in the LARP technology, a conversion element arranged at a distance from the radiation source and comprising or consisting of excitation radiation is irradiated with excitation radiation, in particular an excitation beam (pumping beam, pump laser beam), in particular with an excitation beam of a laser diode. The excitation radiation of the excitation beam is absorbed by the phosphor and at least partially converted into a conversion radiation (emission radiation) whose wavelengths and thus spectral properties and / or color are determined by the conversion properties of the phosphor.

In an alternative or additional embodiment of the invention can be provided that the radiation source arrangement comprises a plurality of modules. In this case, at least one module can have a comparatively cool light color, in particular a broad blue illumination or cold white illumination. At least one other module can then have a comparatively warm light color or yellow or warm white illumination. The further module can then, in particular in the central area of the total radiation, mix appropriate light if required. Thus, the at least one module with the comparatively warm light color in a central region of the illumination in a vehicle can emit light radiation in addition to the at least one module with the comparatively cold light color.

According to the invention, a vehicle headlight is provided with a lighting device according to one or more of the preceding aspects. The vehicle headlight is used, for example, for a lighting function, for a signal light function or for a coming home function.

In a method according to the invention for controlling a lighting device according to one or more of the preceding aspects, it is provided that the light color, in particular the blue light component, of at least one subset of a Overall radiation of the light radiation is adjusted via an adjustment function.

In the method, it can additionally be provided that, in the case of detection of external, in particular comparatively bright radiation sources, such as oncoming traffic or glare, by a sensor of the light device, the light color of at least a subset of the total radiation in the direction of longer wavelength and / or in the direction away from blue or blue-green and / or in the direction of a reduction of the blue light component or blue-green light component is adjusted. Alternatively or additionally, it may be provided that, after the external bright radiation source is no longer detectable by the sensor, the light color at least a subset of the total radiation of the light radiation in the direction of shortwave and / or toward blue or blue-green and / or in the direction an increase in the blue light component or blue-green light component, in particular comparatively slowly, is adjusted or increased. Thus, in oncoming traffic or glare or too bright light sources, that is, in a photopic adaptation of the eye, the blue component can be reduced and increased again slowly after disappearance of the cause of glare, and this can be adapted to the adaptation curve of the human eye. Thus, with an interim return to photopic vision, the blue function can be back-regulated, resulting in improved visibility for the driver and then increased again.

The vehicle may be an aircraft or a waterborne vehicle or a land vehicle. The land-based vehicle may be a motor vehicle or a rail vehicle or a bicycle. Particularly preferred is the use of the vehicle headlight in a truck or passenger car or motorcycle.

In the following, the invention will be explained in more detail with reference to an embodiment. The figures show:

1a to 1c Explanations regarding the visual abilities of the human eye in each case in an axis diagram

2 in a schematic representation of a vehicle headlight with a lighting device according to an embodiment

As already explained, the human eye has rods and cones. Pins are available for the colors blue, red and green. A relative sensitivity of the various cones and rods to a wavelength of light is 1a shown. The ordinate indicates the relative sensitivity in percent and the abscissa the wavelength in nanometers. Furthermore, there is a curve 2 for blue cones, a curve 4 for green cones, a curve 6 for red cones and a curve 8th shown for the chopsticks. It can be seen that the blue cones according to the curve 2 have an absorption maximum at about 420 nm, which corresponds to the color blue-violet. An absorption maximum of the green cones according to the curve 4 is 534nm and corresponds to the color emerald green. For the red cones according to the curve 6 is the absorption maximum at 564nm, which is the color yellow. The responsible for the night vision rods have according to the curve 8th their absorption maximum at 498nm.

In 1b On the ordinate is a luminous efficacy in lumens per watt and on the abscissa the wavelength of a light in nanometers. A curve 10 shows here a luminous efficacy of a brightly adapted eye (photopic area), a curve 12 the light output of a dark adapted eye (scotopic area) and a curve 14 the light output of the eye in the transition from photopic to scotopic vision. According to the curve 10 the maximum of the brightly adapted eye is 555nm, with the dark adapted eye according to the curve 12 at 507nm. This shift is the "Purkinje effect".

In 1c For example, a relative intensity threshold is plotted logarithmically on the ordinate, and a time in minutes on the abscissa. A transition from photopic to scotopic vision takes place along a curve 16 , which is shown by a solid line. An adaptation time to the transition point 18 is about five to ten minutes and is accompanied by a shift in color sensitivity to blue-green.

In 2 is a vehicle headlight 20 for a vehicle with a lighting device 22 shown. This has a radiation source arrangement 24 , with a light radiation 26 is emissive. Furthermore, there is a control unit 28 provided with a light color of the light radiation 26 is adjustable via an adjustment function. About a sensor 30 a degree of mesopic and scotopic and photopic vision can be determined. The control unit 28 then takes into account the values of the sensor to adjust the light color 30 , Furthermore, the setting of the light color depends on a speed of the vehicle headlight 20 starting vehicle from. The speed is here via a sensor 32 measured.

Disclosed is a lighting device or a light module for a headlamp with a radiation source that emits light radiation. In the case of light radiation, a light color can be set in particular as a function of a sensor which determines a degree of mesopic and scotopic vision.

LIST OF REFERENCE NUMBERS

2

Curve blue cones

4

Curve green cones

6

Curve red cones

8th

Curve Chopsticks

10

Curve light-adapted eye

12

Curve dark-adapted eye

14

Curve transition area

16

curve

18

Transition point

20

vehicle headlights

22

light device

24

Radiation source assembly

26

light radiation

28

control unit

30

sensor

32

sensor

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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.

Cited patent literature

• US 20060044818 A1 [0002]

Claims (14)

Lighting device for a headlight ( 20 ) with at least one radiation source arrangement ( 24 ) over which a light radiation ( 26 ), wherein a light color, in particular a blue light component, at least a subset of the light radiation ( 26 ), is adjustable via an adjustment function. Lighting device according to claim 1, wherein a sensor ( 30 ) is provided, via which a degree of mesopic and / or scotopic and / or photopic vision can be determined, and wherein the adjustment of the light color as a function of a sensor signal of the sensor ( 30 ) he follows. Lighting device according to claim 1 or 2, wherein the adjustment of the light color of a speed of a light device ( 22 ) Dependent vehicle is dependent or adjustable. Lighting device according to claim 3, wherein at increasing speed, the light color in the direction of shorter-wave light radiation or in the direction of blue or blue-green or in the direction of increasing the blue light component or blue-green light component is adjusted, and wherein with decreasing speed, the light color in the direction of longer-wave light radiation or in the direction away from blue or blue-green or towards a reduction of the blue light portion or blue-green light portion. Lighting device according to one of the preceding claims, wherein a displacement of the light color of the light radiation is a color sum value of a total radiation in the white field, which is predetermined by the Economic Commission for Europe (ECE) or a mandatory standard. Lighting device according to one of the preceding claims, wherein the adjustment of the light color is linear or non-linear. Lighting device according to one of the preceding claims, wherein an adjustment of the light color or an adjustment function of the light color depending on an illumination function of the headlamp ( 2 ). Lighting device according to one of the preceding claims, wherein a sensor for detecting a steering angle is provided, and the light color is adjustable in dependence of the steering angle. Lighting device according to one of the preceding claims, wherein the light color in certain angular ranges and / or Abstrahlbereichen is adjustable. Lighting device according to one of the preceding claims, wherein the adjustment of the light color depends on the location of the light device ( 22 ). Vehicle headlight with a lighting device according to one of the preceding claims. Method for controlling a lighting device according to one of claims 1 to 10, wherein the light color, in particular the blue light component, at least a subset of the light radiation ( 26 ) is adjusted via an adjustment function. Method according to claim 12, wherein upon detection of external radiation sources or of certain external radiation sources by a sensor of the light device ( 22 ) the light color of at least a subset of the light radiation ( 26 ) in the direction of longer wavelength or in the direction away from blue or blue-green or in the direction of a reduction of the blue light component or blue-green light component is adjusted. The method of claim 13, wherein, after the external radiation source is no longer detectable by the sensor, the light color, at least the subset of the light radiation ( 26 ), in the direction of shortwave or in the direction of blue or blue-green or in the direction of an increase in the blue light component or blue-green light component is adjusted.

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