Method and device for controlling the emission of light of a head lamp arrangement of a vehicle

Method for controlling the light emission and arrangement of a vehicle headlight for implementing the method.

The invention relates to a method for controlling the light emission of a vehicle headlight arrangement, comprising a headlight whose light emission is controlled by means of at least one light sensor which senses the light emission. acting on the driver of the vehicle, from the driver's field of vision in the direction of travel of the vehicle.

Such a method is known from document DE OS 21 44 197. In this case two low beam headlamps, which emit light beams strongly oriented on the running track, are provided on a vehicle, with a view to improving the illumination of the runway. In addition, two additional projectors are provided, which are designed as long-range projectors, but whose light emission is, however, for each, controlled by a light sensor, so that they can be darkened in different areas of the light. the runway using a light / dark boundary extending vertically. The control then works in such a way that if the light sensors pick up a light coming from the opposite direction, it follows, each time, a darkening in the area of ​​the incident light in the field located in front of the vehicle, so that the driver of the oncoming vehicle is not blinded by the additional headlamps. In the other areas, the taxiway is fully lit. In operation, the four projectors are thus permanently connected. The light emission from the additional headlamps is then selectively interrupted.

This device has the drawback that due to complete darkness in the direction of the oncoming vehicle, the running track is insufficiently lit in this direction and black holes appear in the driver's field of vision, which can lead to dangerous traffic situations in the pedestrian zone. Also inside these black holes the light coming from the oncoming vehicle acts violently on the driver of the vehicle of the known headlamp arrangement and it can blind him noticeably, due to the differences in brightness between the vehicle. black hole and oncoming light.

With respect to this technical state of the art, the method according to the invention is characterized in that the light intensity is measured at least in the area of ​​the field of vision, in which light sources can appear in the opposite direction to the roadway, it is compared to a threshold value and if this value is exceeded, the light emission of the headlamp arrangement and / or the light distribution of this arrangement is increased, in order to increase the illumination of the road to be followed by the vehicle in the direction of travel.

This method has the advantage that in the case of oncoming light, the light which specially illuminates the raceway is enhanced so as to reduce the light contrast between the illuminated raceway and the oncoming light. . Thus the blindness of the driver is also limited. Thanks to the high level of illumination, the driver achieves the visual acuity that he has in normal illumination, without a vehicle coming to meet him. Advantageously, the increase in the light emission of the vehicle is controlled automatically, namely when the light intensity or the light emission in the driver's field of vision has reached a determined threshold value. This threshold value can be optimized. The introduction of such a threshold value offers the advantage that the increase in the light emission of the projector does not occur too early or too late. If the augmentation occurs too early, too early habituation to the high light output follows, so that part of the initial benefit in visual acuity is again lost. The effect of diminishing visual acuity as a result of the effect of blindness by the light of the headlights of the approaching vehicle is not significantly reduced.

The invention is further improved by the fact that:

a) In the area of ​​the field of vision, outside the oncoming roadway, in which light reflections due to the light emission from the headlamp arrangement and acting on the driver can occur, the light intensity is sensed using the light sensor and if a threshold value is exceeded by the light intensity, the light emission of the headlamp arrangement is reduced and / or the light distribution is changed, in order to reduce the light intensity in the direction emitted in the direction of these areas.

b) The modification of the light distribution is carried out so as to reduce the light emission in the direction of the zone of the field of vision from which the light emission that exceeds the threshold value originates.

c) The change in light distribution is achieved by changing the position of the maximum light intensity of the light emission of the headlamp arrangement.

d) The change in light distribution is achieved by changing a bright / dark limit of light emission from the headlamp arrangement.

f) The increase or modification of the light distribution is carried out for a predetermined minimum period, after the threshold value has been exceeded.

g) A headlamp may be switched on or off with a view to modifying the light emission or the light distribution of the headlamp arrangement.

h) The headlamp arrangement for carrying out the method comprises a light sensor, provided with an optic placed upstream, arranged on the front of the vehicle, optic facing towards the field of vision of the driver of the vehicle , a control device connected to the output of the light sensor and a device for modifying the light emission of a headlamp of the headlamp arrangement, this arrangement being characterized in that the light sensor has at least one light receiving field, on which at least one light emitting field of the field of view can be reproduced through optics.

i) Several light sensors are provided which are associated with different zones of the field of vision or groups of light sensors which are associated with different zones of the field of vision. These sensors or groups of sensors being connected, each one after the other, to an operating circuit of a control device comprising a comparator device connected on the one hand to a threshold value transmitter relating to a value. light emission and on the other hand to the light sensor or to the group of light sensors, the output values ​​of the comparator being fed, by means of a signal memory and in particular by means of a logic combinatorial circuit, to an adjustment or connection device by means of which the light emission of a headlamp of the arrangement of projector is changeable.

j) Several light sensors or a light sensor are provided with groups of photosensitive elements, associated with the different zones of the field of vision, while the outputs of these sensors or of these photosensitive elements are connected to a comparison device of threshold value whose outputs are connected to a logic combinatorial circuit which is connected to an adjustment or connection device, by means of which the light emission of the projector is modified.

k) A single light sensor is provided, downstream of the optics of which is arranged a scanning device with the aid of which the different partial areas of the field of vision are reproduced one after the other on a photosensitive element of the sensor brightness, and in that the output of the photosensitive element is connected to a circuit by means of which the output signals of the photosensitive element are supplied, at the scanning frequency of the scanning device, to an evaluation circuit having a comparator device, the output values ​​of the comparator device being connected, by a signal memory, in particular by a logic combinatorial circuit, to an adjustment or connection device by means of which the light emission of the projector is changeable.

l) The field of view is represented on several photosensitive elements of one or more luminosity sensors, the outputs of the photosensitive elements being at the same time connected to a logical combinatorial circuit, through which one can measure a maximum value of the output signals of the individual photosensitive elements, this maximum value being fed to a threshold value comparator device, the output signal of which controls an adjustment or disconnection device, with the aid of which the light emission of the headlamp can be modified.

m) The adjustment or connection device can be connected and disconnected at will. The installation can thus be switched if required.

n) The adjustment and connection device can be maintained for a predetermined time in the connected or disconnected position, by means of a timed element which can be positioned due to a first connection or a first login process. This advantageously avoids too high a connection frequency.

o) The adjustment or connection device comprises a servomotor using which a screen can be interposed in the light beam emitted by the headlamp or else using which the position of the light source can be modified.

p) The adjustment or connection device has a relay with the help of which the intensity going to the light source of the projector can be connected or disconnected.

q) The screen has a screen edge extending vertically.

The present invention is described and explained with reference to preferred embodiments, and in connection with (the accompanying figures) given by way of illustration, in which:

- Figure 1 is a basic representation of a projector arrangement for performing the method according to the invention,

- Figure 2 shows the structure of a first embodiment of a brightness sensor for measuring the light emission from the field of vision of the driver of the vehicle equipped with the projector arrangement, a field receiving light being delimited by a screen,

- Figure 3 shows a second embodiment of the light sensor, in which the light receiving field consists of several individual photosensitive elements,

- Figure 4 shows a third embodiment as a variant of the embodiment of Figure 3,

- Figure 5 shows a fourth embodiment comprising a single photosensitive element, on which the field of view is reproduced by a device deflecting the light in rapid alternation using a scanning method,

FIG. 6 represents a distribution of the driver's field of vision into different fields emitting light and which are copied onto a field of the photo sensor receiving the corresponding light,

FIG. 7 is an electrical diagram of the circuit for processing the output signal of the photo sensor,

FIG. 8 is a block diagram of a variant of a light design control device of a vehicle headlight arrangement.

On a motor vehicle, not shown in detail, there is a light sensor 1 at the front which is oriented in the direction of travel and captures the field of vision of the driver of the vehicle. The light sensor consists of an image or field optic 2 downstream of which is provided, in the image plane, one or more photosensitive elements 3, which constitutes a receiving field 4 of the light. The photosensitive elements deliver, through their output 6, control signals to an operating circuit 7, the output 8 of which is connected to a connection device 9, through which the emission or distribution of the signal is controlled. projector light 11. This headlamp can be either an additional headlamp, which may or may not be connected in support of a code projector, or a modified headlamp or a code projector belonging to the standard vehicle equipment, which is controlled so that its light emission takes place as desired. The headlamp must then increase the light emission in the direction of the runway proper, as a low beam light, when a light source occurs on the reverse runway, or even reduce the light emission if it excessively high light emission occurs from specific areas of the driver's field of vision. This will be explained in more detail below. The operating circuit consists in principle of an amplifier 12 amplifying the signals coming from the output 6 and bringing them to a threshold switch 14, with which is associated a threshold value sensor 15. The output of the Threshold value switch controls a power transistor 16 or other switching element, through which a power circuit can be controlled. The power transistor 16 preferably controls the connection device 9 which may for example consist of a relay 17 controlling the power supply circuit of a low beam headlamp 11, ensuring its connection or disconnection. As a variant, it is possible to control by means of the connection device a device for adjusting the headlight or an additional light source located in the headlight or a dimming device of the headlight.

In order to understand the device described above, the field of vision of the driver of the vehicle according to FIG. 6 will be taken into consideration. It can be seen there that the field of vision is subdivided into three fields emitting light, a first field 18, a second field 19 and a third field 20.

The first light emitting field 18 comprises, the rolling track 22, which is already designated above as the actual rolling track of the vehicle equipped with the headlight arrangement according to the invention, the edge 23 of this track. runway, as well as, up to certain limits, zone 24 located above the runway 22 or its edge 23.

The second light emitting field 19 comprises the reverse rolling track 25 its edge 26, as well as a zone 27 also situated above them.

The third light-emitting field is located above areas 24 and 27 of the first and second light-emitting field and comprises the light sources located beyond a determined height or a determined angle, at above the runways. In this area of ​​the third field, light emissions occur which can come from light sources located at a height, light reflection on structures such as bridges or light reflection on fog sheets.

Due to the brightness of FIG. 1, the photosensitive element 3, embodiment of the sensor comprising the optics 2, and a representation of the light-emitting fields on the light-receiving field 4 is obtained and one proceeds to a exploitation of this light emission. The light emission of the field is brought to the amplifier 12 in the form of a signal, then in the switch 14 with adjustable threshold value which drives the power transistor 16 that is to say the adjustment circuit 9 after each going up or down the threshold value. The threshold value can be adjusted manually or automatically, according to a general light level, the speed of the vehicle, or according to various other parameters influencing visual acuity. The device works in such a way that when the signal level corresponding to the light coming from the second field 19 exceeds the expected threshold value, the switch 14 connects the projector 11 through the connection device 9, as a light. crossing, that is to say increases the light emission of the vehicle in the direction of the directional track 22. If, on the other hand, the light emission of the first field and / or of the third field exceeds the predetermined threshold value, there is disconnection of the low beam, of the headlight 11 or of a similar device, in order to reduce the illumination. runway 22.

This happens in particular when, by increasing the light emission and visibility conditions, the directional track of the vehicle is too brightly lit or if, due to the increased light emission when the vehicle arrives on reflective surfaces, the driver may be excessively blinded. This happens in particular with the formation of fog. In order to exploit the light emissions coming from the light-emitting fields, these are transmitted to the light sensor 1 so that, with the aid of the optics or the light-receiving fields 4, produced in such a way correspondingly, the light-emitting fields can be selectively exploited as desired.

A first embodiment of the brightness sensor 1 is shown in Figure 2. An optic 2 is shown schematically, in the form of a converging lens, downstream of which is placed another converging lens 29, which leads to its turn the light received by optics 2 to a corresponding signal output being at its photosensitive element 3. The corresponding light emitting field which is located in the driver's field of vision can then be delimited by means of a screen 30 placed upstream of the converging lens 29, constituting the light receiving field 4. The photosensitive element 3, which is associated with a determined light-emitting field, captures the sum of the light emission of the light-emitting field, forms a signal of this light emission, this turn processed in the circuit of operation 7, to determine the crossing of the threshold value in ascent or descent, this crossing then being used as described above. Such a sensor can be associated with individual fields emitting light.

By way of improvement of FIG. 2, it is also possible to produce a luminosity sensor such that the optic 2 represents the fields emitting light on an arrangement 32 of several photosensitive elements. It is then possible to provide individual photosensitive elements 33 arranged in series, one or more of which is associated with one of the fields 18, 19, 20. The output signals of these individual photosensitive elements are exploited individually or in a grouped manner, by the operating circuit, if there are several per field. It is then possible to provide a single operating circuit for the whole of the arrangement 32 of the photosensitive elements, if each of the photosensitive elements 33 associated with light-emitting fields are the subject of an exploitation one after the other. , in rapid succession. The projector 11 is then connected as a function of the result of the measurements.

Figure 4 shows a variant of the embodiment of Figure 3, also comprising individual photosensitive elements 33 arranged in a row and whose surfaces give representations of the light-emitting fields, while converging optics 34 are placed upstream of each of these elements. A 1¹ With the help of these optics 34 which are advantageously cylindrical, the individual photosensitive elements 33 can be exactly associated with the light emitting fields.

If one wishes to reduce the expense relating to the use of a large number of photosensitive elements, in particular according to FIG. 4, it is possible (see FIG. 5) to implement a single photosensitive element 36, by placing in upstream of this element, an optic configured in a corresponding manner and by placing a corresponding operating circuit downstream.

There is provided in Figure 5, as in the previous figures, an optic 2 downstream of which is placed an oscillating mirror 37. This mirror is moved in a back and forth movement of regular amplitude by a drive 38 and then explores by means of the optic 2 the different zones of the field of vision of the driver of the vehicle and produces for each, a representation on the photosensitive element 36, by means of a converging lens 39 placed downstream . All the parts of the field of vision are therefore successively represented and in particular the fields 18 and 19 emitting light. The output signal of

1. the photosensitive element is scanned sequentially and synchronized with the movement of the oscillating mirror and operated through a threshold value switch which in turn controls the low beam or headlight 11 in the aforementioned manner . The operating circuits of the preceding embodiments can contain a comparator device, the threshold value switch 14, working with identical threshold values, for all the fields emitting light, or on the contrary with threshold values. different. In the latter case, too frequent switching of the dipped headlight is avoided in the event of unfavorable visibility conditions. In order to avoid switching in special cases with increased light emission from the first light-emitting field, for example when there are reflective surfaces on the edge of the runway, which may increase briefly the light emission from this field

18.

There will be provided at this location of the light emitting fields 4 or at the corresponding location of the photosensitive elements 33, a covering corresponding to the surface 40 which is hatched on the increased luminous of the panels of the signals of FIG. 6. Such emissions can eg coming from reflective traffic or traffic, in this way the light emissions coming from this area do not contribute to the control of the low beam. If the light sensor consists of a large number of photosensitive elements, the photosensitive elements located in this area can be omitted.

There is shown in Figure 7 an operating circuit 107 comprising sensors la, lb, le, each associated with one of the fields 18, 19, 20, emitting light, downstream of these sensors are placed amplifiers 12a, 12b, 12c, followed by inter2641237 threshold breakers 14a, 14b, 14c. The output of each threshold value switch leads to switches 16a, 16b and 16c which are each associated with the brightness sensors 1a to 1c, and which are placed in series in an electrical supply line 42. The supply line electrical 42 leads to the connection device 9, through which the headlamp 11 or the low beam is connected. In addition to the switches 16a, 16b, 16c, an additional switch 43 is also provided, which is controlled by a switching device 44 which can be actuated at will by the driver of the vehicle.

This operating circuit makes it possible to obtain a measurement of the light emission coming from the fields emitting light and, in the event of crossing, on the rise or the descent, of a threshold value, it can give priority to this state of affairs, in relation to the conditions prevailing in the rest of the light-emitting surfaces, by temporarily connecting or disconnecting the low beam. The brightness sensor 1a is associated, for example with the first field 18 emitting light, the sensor 1b with the second field 19 and the sensor 1c with the third field 20. Depending on the switching logic of the connection device 9, the conditions can then be such that if the threshold values ​​associated with the first and third light-emitting fields 18, 20 are not exceeded, the corresponding switches 16b and 16c are closed. , so that then, when the switch 43 is also closed, the connection arrangement is engaged in such a way that the low beam 11 is connected. If the threshold value which is associated with the second field 19 is crossed in descent, the switch 16b opens, the relay of the connection device 9 drops out and the low beam is again disconnected. The same process occurs if the threshold value that is associated with the first field 18 or the third field 20 is exceeded. The switches 16a and 16c then open and the electrical circuit is also interrupted. By actuating the connection device 44, it is also possible to switch off the dipped beam headlight also via 1.¹ switch 43.

In addition to this embodiment, in order to avoid too frequent switching when passing predetermined threshold values, an additional device can be provided comprising an intensity recognition sensor 46 which recognizes, by being produced for example under in the form of an induction coil, an intensity passing through the power supply line 16, the sensor is associated with a time delay switch 47 to control it. The time-delayed switch is located in an electric line 48 placed in parallel with the switches 16a to 16c and 43, and starts from a current source or a voltage source, on which the rest of the installation 49 of the projector is plugged. As soon as the device 46 detects a current, the electric line 48 is connected by the time switch to the connection device 9, so that, during the predetermined delay time of the time switch, the connection device 9 remains under attack, regardless of the position of switches 16a to 16c. Then, at the end of the delay time, the electric line 48 going from the connection device 9 is again interrupted and the latter is controlled by the aforementioned switches according to their positions.

According to an alternative embodiment, an evaluation circuit can be made so that, for sensor configurations according to FIG. 3 or 4, the individual photosensitive elements 33 are scanned in an order of rapid succession and a predetermined frequency, and compared. at a predetermined threshold value or even alternately switchable. Each measurement result is placed in a memory which is then interrogated to find out the highest value which is decisive for the switching of the low beam. The operation is thus carried out in multiplex technique. According to another embodiment, the individual photosensitive elements according to FIGS. 3 or 4 can be interrogated by means of an analog grid to know the highest values, each maximum value in turn determining the switching of the connection device. , respectively for example the connection or disconnection of the low beam.

Such a device is shown schematically in FIG. 8, with an optic 2, an arrangement 32 of several photosensitive elements 33 and a threshold value device 50, through which a maximum value 51 exceeding the threshold value 52 is detected. and depending on which connection device 9 is attacked. A servomotor 54 can now be connected by means of the connection device 9, which motor is used to adjust a screen 55 engaging in the path of the beam 56 of a low beam headlamp 57. The high beam headlamp crossing comprises a light source 58 which is then constantly connected, together with the rest of the installation of projectors and a reflector 59 comprising a downstream lens 60. The edge 61 of the screen 55 is positioned to match the runway or the field of

264 1237, driver's vision. Regarding this screen, it is a screen producing a vertical light / dark limit, so that only the directional running track 22 is illuminated each time. In principle, the light distribution of the light emission of the projector can then be changed and in particular the change can be undertaken so that in the direction 62, from which a signal exceeding a predetermined threshold value is taken, a light abundant is emitted and that, in the other zone, no light is emitted, or little light. A variant is shown in Figure 8, with the aid of which instead of the screen 15, it is the light source 58 which is moved with the aid of a servomotor 63, so that the position of the The highest luminous intensity 64 of the light emitted by the installation of headlamps, on the directional track 22 of the vehicle, is limited in the field of vision 65.

With the aid of the preceding measurements, when an increased light level occurs on the reverse rolling track, the illumination intensity of the rolling track 22 on which the vehicle is moving is advantageously increased in the zone of the first field 18 emitting. light, in order to improve the visual acuity of the driver of the vehicle or to reduce the illumination contrast between the light coming from the front and the running track itself which is illuminated. If, however, the light emission from the first light-emitting field is too high, which can be caused by reflective surfaces, by reflective coatings of the reflective runway or for particular atmospheric conditions such as slicks fog light, the low beam is disconnected. In such cases an additional field is also provided, the third field 20, through which the low beam is controlled in the same way.