DE10034555A1 - Light sensitive sensor unit, especially for automatically switching lights, has light conducting elements associated with sensors connected in one piece to light conducting body - Google Patents

Abstract

The unit has at least two light sensitive sensors with associated light conducting elements with a definable reception characteristic. At least a first sensor and a second sensor detect light characteristics in at least two defined directions. The light conducting elements (14,14a) associated with the sensors are connected in one piece to a light conducting body (18) integrated into the light conducting body of a rain sensor (110).

Description

State of the art

The invention is based on a photosensitive Sensor unit, in particular for the automatic switching of Lighting devices in vehicles, according to the genus Claim 1.

Such a sensor unit is described in DE 195 23 262 known that a global sensor and a direction sensor includes through which the lighting conditions outside the Vehicle can be detected. The sensor unit is with the Evaluation device connected in which from the signals of Sensor unit is determined whether the current existing lighting conditions in the vicinity of the Vehicle a change in the switching state of the Lighting equipment is required. This well-known Sensor unit allows automatic switching of the Lighting devices too, however, it includes through the Global and directional sensors relatively many parts what causes considerable costs and a complex adjustment.  

Advantages of the invention

The inventive device with the features of Claim 1 has the advantage that by integrating Global and direction sensors a simple, compact, robust, easy to install and practically adjustment-free Sensor unit is available. To this end, the Set up a minimal number of components what a simple and inexpensive production with advanced Functionality enables. Because on windshields from Motor vehicles the size of obstructing components should be kept low, the low prove Dimensions resulting from the integration of global and Direction sensors are possible as another great advantage. By integrating the light guide body of the sensor unit can in a light guide body of a rain sensor device additional components can be saved and the number of components obstructing the view on the windshield can be further reduced.

Especially when the light guide body in one multi-component injection molding process together with the Light guide body of the rain sensor and the coupling medium further steps can be saved become.

By the features listed in the subclaims advantageous developments of the sensor unit according to Main claim possible.

Because at least three sensors light off Detect predetermined directions will continue Area recorded in front of the vehicle.

If at least one sensor in the direction of travel as well as the two other sensors on both sides by an angle α from the  Swiveled out direction are arranged there is a wide detection cone in front of the vehicle, so that even tunnel entrances that are not yet in the direction of travel lie, are detected and the lighting device can be controlled accordingly.

If the direction sensors have lens-like elements, which can also merge into one another Acquisition cone individually to the wishes of the Vehicle manufacturer to be matched.

If the light-guiding elements merge into one another, it can continue Space is saved and the sensor unit continues be minimized.

Can the sensor elements use daylight and artificial light distinguish can be prevented that the Lighting devices when driving in tunnels in brighter Lighting can be switched off.

It is advantageous in the sensor unit according to the invention also a significant improvement in Response behavior of the rain sensor device which itself by increasing the ratio of sensitive area to the contact surface in comparison to conventional rain sensors established. This is due to the trapezoidal arrangement of the Sender and receiver reached. By the elongated contiguous sensitive area, the Probability that one on the disc Raindrops through the wind on the sensitive surface drifts increased, which is a significant improvement in Response behavior.

By using several receivers per transmitter, the Number of measuring sections and thus the number of sensitive Areas increased, which results in a further cost advantage.  

The same effect occurs when multiple stations and only one Receiver can be used. Become two transmitters and two Used receivers, four measuring sections and thus four sensitive areas can be achieved. Is the distance between the two Transmitter about twice the distance of the two receivers large, there is a particularly uniform arrangement of the sensitive areas.

It also proves to be advantageous that Fix rain sensor device on the pane so that the transmitters in the installation position on the lower parallel and the Receiver arranged on the upper parallel of the trapezoid are. Sun exposure, which is preferably from above and represents disturbing extraneous light, can thus on the Be minimized.

Due to the improved properties, especially through the improved ratio between sensitive area and Contact surface, the contact surface of the sensor can be reduced be, which affects the outer dimensions of the sensor reduce the disc. It is particularly advantageous that due to the trapezoidal arrangement of the transmitters and receivers the outer dimensions of the sensor housing anyway can be chosen rectangular, so that the base with optimal use of the contact surface of the Light guide body can be arranged in this. A rectangular contact surface or housing affects it also reduce costs in manufacturing. Moreover represents the smaller contact surface of the light guide body essential assembly advantage, since at constant Contact pressure increases the contact pressure and thus a disruptive Bubble formation between the coupling medium and the disk can be avoided. Here it is also possible to use a slight curvature of the surface of the disc facing Lichtleitkörper on the light inputs and / or  Light exit areas partially target the surface pressure increase.

Furthermore, it proves advantageous that in the Arrangement of two transmitters or two receivers on each opposite parallel sides are arranged. Now that four measuring sections, i.e. H. four sensitive areas of the Sensors with only two transmitters and receivers each realized, there is a significant cost advantage.

drawing

An embodiment of the invention is shown in FIGS. 1 and 2 and explained in more detail in the following description. Show it:

Fig. 1 shows a section through an inventive sensor unit,

Fig. 2 integrates an illustration of the sensor unit in a light-guiding body of a rain sensor in a perspective view;

Fig. 3 is a schematic drawing of the contours shows a possible embodiment of the rain sensor device.

Description of the embodiment

Fig. 1 shows an inventive sensor unit 10 which is mounted on a disc 11, in particular a windshield of a motor vehicle. The sensor unit 10 consists of several sensors 12 , each sensor 12 comprising a sensor element 13 and a light guide element 14 , 14 a. Here, however, two light-guiding elements 14 use a sensor element 13 together , so that there are three light-sensitive sensor elements 13 with four light-guiding elements 14 and 14 a. The light-guiding body, on which the light-guiding elements 14 , 14 a are brought up, consists of an at least partially translucent plate which has cylindrical shapes which are finished with lenticular curves. These cylindrical shapes each form a light-guiding element 14 , 14 a with the lenticular curves. If parallel light passes through the lenticular curves along the central axis of the cylindrical formations, there is a focal point f which characterizes a focal length of the light guide element 14 , 14 a.

The sensor elements 13 are each arranged between the focal points f of the light guide elements 14 and the light guide elements 14 themselves. This results in light detection cones pointing forward in the direction of travel, which permit detection in predetermined directions. The opening angle of the light detection cone can be set via the distance between the focal points f of the respectively associated light-guiding element 14 and the light-sensitive sensor elements 13 .

An evaluation device 15 controls the switching of an illumination device 16 as a function of the signals from the sensor elements 13 . The sensor elements 13 can be applied together on a circuit board 17 and are preferably designed such that they can distinguish between daylight and artificial light in order to prevent switching off by the artificial light illumination, for example in a tunnel. This can be achieved by a suitable choice of the sensitivity range of the sensor elements 13 . It is also possible to select the sensitivity range in such a way that certain spectral ranges or characteristic lines, for example of gas discharge lamps, are recognized and thus a control of high and low beam in a motor vehicle is made possible.

In addition to this direction sensor is a light guide at least a not necessarily aligned in the direction of travel 14 to the front. The light detection cone of this at least one light guide element 14 a has a very large opening angle and detects the global light conditions outside the vehicle.

All light guide elements 14 , 14 a, in particular also the sensors of the direction sensor and the global sensor system, are integrally connected to form a light guide body 18 . This light guide body 18 can be made, for example, as an injection molded part from a transparent or UV-transparent plastic. It is also possible to produce the light guide body 18 from a colored or coated plastic, which may contain a desired filter effect to influence the sensitivity range of the sensor. This light guide body is pressed onto the pane via a coupling medium 19 , for example a silicone cushion. The coupling medium 19 prevents air pockets between the pane 11 and the light guide body 18 , which would cause undesirable scattering. It is also possible to apply the coupling medium 19 to the same in a multi-component injection molding process during the manufacture of the light guide body 18 .

This light guide body 18 is an integral part of a light guide body 110 of a rain sensor device.

FIG. 2 shows a light guide body 110 of a rain sensor device shown in section with a sensor housing 111 . The bearing surface of the light guide body 110 is, for example, by the contact thereof via the coupling medium 19 , for. B. given a silicone cushion with the disc 11 . In general, the outer dimensions of the light guide body 110 correspond approximately to the length and width dimensions of the sensor unit, and the sensor housing 111 can also protrude from the contact surface of the light guide body 110 on the pane 11 and various elements of the sensor unit, in particular transmitter 114 and receiver, therein 115 , as well as a circuit board 124 .

The sensor unit is fastened, for example, on the inside of the window 11 , for example a front window of a motor vehicle. The fastening of the sensor housing 111 to the disk 11 is not shown. The light guide body 110 or the sensor housing 111 is preferably attached to the pane 11 by pressing, the light guide body 110 having the function of coupling a transmitter light 117 emitted by a transmitter 114 into the pane 11 and the transmitter light deflected in the pane 11 by total reflection or reflection 120 decouple at another predetermined location on a receiver 115th This is done here on optical elements 116 , which are attached to the light guide body as lenses, preferably formed on them, and which bundle, deflect or deflect the rays of the transmitter light 117 , 120 in the desired direction.

At least one light-emitting transmitter 114 and one light-detecting receiver 115 are fastened within the sensor housing 111 above the light-guiding body 110 in the sectional plane shown. Light-emitting diodes (LED) are preferably used as transmitters and light-detecting diodes (LRD) are preferably used as receivers, the transmitter radiation of the light being in the infrared (IR) or in the visual range (VIS), but any number of others are also Frequency ranges possible. A receiver element corresponding in its construction to a light-emitting diode can also be used as the receiver, as a result of which an optimal frequency adaptation between transmitter 114 and receiver 115 can be achieved. A material, here a plastic, is selected as the material of the light-guiding body 110 , which is transparent for the transmission frequency of the light-emitting diodes (LED) but opaque for interfering external light.

A possible arrangement of the transmitters 114 and receivers 115 can be seen in FIG. 3. The transmitters 114 and receivers 115 of the sensor unit are placed near the optical elements 116 from FIG. 2. Transmitter 114 , receiver 115 and the associated optical elements 116 span a base area 118 , indicated by dashed lines, which corresponds to a trapezoid.

On a first parallel of the trapezoid, two optical elements 116 are arranged near a transmitter 114 each. Because the optical elements 116 are each formed as two lenses arranged next to one another, there are two measuring paths in two directions for each transmitter 114 . Analogously to this, the receivers 115 are arranged. The optical elements 116 consist, for example, of lenses or mirrors, which can also merge into one another. A solution with only one lens at a time is also possible since the resulting misalignments can be kept small by appropriately selecting the distances a and b of the trapezoidal base area 118 .

The distances a and b between the transmitters 114 and the receivers 115 are determined by the wavelength of the emitting radiation from the transmitters 114 , the thickness of the pane 11 and the light guide body 110 , the refractive index of the pane 11 , the entry angle and the entry point of the transmitter light 117 in the disc 11 determines. The distances are selected such that the radiation of the transmitter light 117 coupled into the disk 11 is totally reflected once per measurement section on the outer surface of the disk 11 and is then coupled out of the disk 11 and directed to the receiver 115 .

The sketched sensitive surface 119 corresponds to the areas on the wettable side of the pane 11 where the total reflection of the radiation from the transmitter light 117 takes place when the pane 11 is not wetted. Depending on the arrangement of the transmitters 114 and receivers 115 relative to the pane 11 , the thickness of the pane 113 and the shape of the optical elements 116 , the reflection surfaces of the transmitter light 117 have a specific diameter. According to the invention, however, the named parameters should be so large that an approximately coherent sensitive surface 119 arises from the individual reflection surfaces. This is achieved according to the invention in that the points of intersection of the central axes of the radiation cones 120 of the transmitters 114 lie on a straight line with the wettable side of the pane 11 and are at approximately the same distance.

If there is more than one desired total reflection on the wettable outside of the pane 11 , the distance a or b between the transmitter 114 and receiver 115 or the respectively associated optical elements 116 should be chosen correspondingly larger and the coupling medium 19 only at the coupling-in and coupling-out areas of the To attach light to the disc 11 .

FIG. 4 shows the light guide body 110 of the sensor unit according to the invention according to FIG. 2. Since the trapezoid of transmitters 114 and receivers 115 comprises a shorter and a longer parallel, the light guide body 18 of the sensor unit 10 is arranged for an automatic light control of the motor vehicle — shifted somewhat from the center towards the longer parallel lines. This light guide body 18 is made of a translucent material, the transparency area of which lies in the visual area.

The light guide body 110 and the light guide body 18 are made in one piece, for example in a multi-component injection molding process, but it is also possible to form a plurality of individual parts, in which case the light guide body 18 is inserted into a corresponding recess in the light guide body 110 .

Plexiglass (PMMA) is often used as the material for the light guide body 110 , since it is inexpensive and easy to process. However, since transparency is only required in the area of the transmitter light, another plastic is also conceivable. A light guide body material is also particularly suitable which, for example by a chemical or physical process, has softer and more elastic properties on the side facing the disk 11 than on the side facing away from the disk 11 , since the coupling medium 19 can thus be saved.

To the filter characteristics of the light guide to reach 110, the material 110 may be certain substances, in particular soot particles, are spatially selectively added during the manufacturing process of the optical waveguide. For example, only the areas required for the function can be transparent to the transmitter light 117 . An analogous procedure is also possible for the coupling medium 19 .

In further variants, a transmitter 114 and a receiver 115 are placed at each corner point of the trapezoid or only one transmitter 114 is used for the entire trapezoid, in which case the optical elements 116 then have reflective properties in order to nevertheless emit transmitter light 117 into the pane at several corner points of the trapezoid 11 to be able to couple. It also makes sense to provide a special heater for the integrated light guide body 18 , 110 in order to heat the measuring section and / or the light guide body 18 , 110 . This heater can be arranged, for example, as a heating element on the light guide body or else can be realized by means of heating coils, heating wires or the like integrated in the light guide body 18 and / or 110 . This is not a problem if the light guide body 18 , 110 is formed homogeneously. If, on the other hand, different plastics are used, for example, in a multi-component injection molding process, the expansion coefficients of the different plastics must be selected accordingly in order to avoid stresses or even cracks in the light guide body 18 , 110 . For this purpose, other measures, such as, for example, an advantageous arrangement of the heating elements or wires, can also be taken.

Claims (27)

1. Light-sensitive sensor unit ( 10 ), in particular for the automatic switching of lighting devices, preferably of motor vehicles, which comprises at least two light-sensitive sensors ( 12 ) to which light-guiding elements ( 14 , 14 a) are assigned, which have a predeterminable reception characteristic, at least a first one Sensor ( 12 ) and a second sensor ( 12 ) detect the light conditions in at least two predetermined directions, characterized in that the light guide elements ( 14 , 14 a) assigned to the sensors ( 12 ) are integrally connected to form a light guide body ( 18 ), the light guide body ( 18 ) is integrated in a light guide body of a rain sensor device ( 110 ), in particular in one piece. 2. Sensor unit according to claim 1, characterized in that at least three sensors ( 12 ) detect light from predetermined directions. 3. Sensor unit according to one of claims 1 or 2, characterized in that at least one sensor ( 12 ) is aligned with a predetermined direction in the direction of travel of a vehicle. 4. Sensor unit according to one or more of claims 1 to 3, characterized in that at least one sensor ( 12 ), which detects the light conditions in a predetermined direction, includes an angle α with a straight line in the direction of travel of a vehicle. 5. Sensor unit according to claim 4, characterized in that two sensors ( 12 ) each include an angle α on both sides with a straight line pointing in the direction of travel and have a common light-sensitive sensor element ( 13 ). 6. Sensor unit according to one of claims 1-5, characterized in that the light guide elements ( 14 , 14 a) merge into one another. 7. Sensor unit according to one of the preceding claims, characterized in that the light detection cone of the light guide elements ( 14 , 14 a) are overlapped. 8. Sensor unit according to one of the preceding claims, characterized in that the sensor elements ( 13 ) are designed as daylight and artificial light differentiating sensor elements ( 13 ). 9. Sensor unit according to one of the preceding claims, characterized in that the evaluation device ( 15 ) is designed as a daylight and artificial light distinguishing evaluation device ( 15 ). 10. Sensor unit according to claim 1, characterized in that the light guide body ( 18 , 110 ) is produced in a multi-component injection molding process, in particular together with the light guide body of the rain sensor and a coupling medium ( 19 ). 11. Sensor unit according to one or more of the preceding claims, characterized in that the rain sensor at least one transmitter ( 114 ), at least one receiver ( 115 ) and at least one light guide body ( 110 ) between the disc ( 11 ) and transmitter ( 114 ) or receiver ( 115 ) and the images of the transmitters ( 114 ) and the receivers ( 115 ) form the corner points of a trapezoid by projection onto the pane ( 11 ). 12. Sensor unit according to claim 11, characterized in that between the transmitter ( 114 ) and receiver ( 115 ) the radiation is reflected at least once on a surface of the disc ( 11 ), wherein the at least one transmitter ( 114 ) emits radiation in different directions and the resulting reflection surfaces result in an at least approximately coherent sensitive surface ( 119 ). 13. Sensor unit according to claim 11, characterized in that at least one transmitter ( 114 ) emits radiation in two directions to two receivers ( 115 ). 14. Sensor unit according to claim 11, characterized in that at least one receiver ( 115 ) receives radiation from two directions from two transmitters ( 114 ). 15. Sensor unit according to one or more of claims 11 to 14, characterized in that the number of transmitters ( 114 ) and receivers ( 115 ) is two in each case. 16. Sensor unit according to claim 15, characterized in that the trapezoid is a symmetrical trapezoid wherein the distances between the two transmitters ( 114 ) from the distances of the two receivers ( 115 ) are so different that the one distance is approximately twice the other distance , 17. Sensor unit according to one or more of the claims 11 to 16, characterized in that the Rain sensor device has four measuring sections. 18. Sensor unit according to claim 16, characterized in that the transmitters ( 114 ) are arranged on the first, in the installed position, lower parallels and the receivers ( 115 ) on the second, in the installed position, upper parallels of the trapezoid. 19. Sensor unit according to one or more of claims 11 to 18, characterized in that the centers of the reflection surfaces of the radiation cone ( 120 ) of the at least one transmitter ( 114 ) in the disc ( 113 ) are arranged next to one another at an approximately equal distance, preferably on a line that is between the two parallels of the trapezoid. 20. Sensor unit according to one or more of claims 11 to 19, characterized in that the light guide body ( 110 ), transmitter ( 114 ) and receiver ( 115 ) are designed and arranged such that in the disc ( 11 ) only a single total reflection of the transmitter light ( 117 ) occurs. 21. Sensor unit according to one or more of claims 11 to 20, characterized in that in each case a transmitter ( 114 ) or receiver ( 115 ) on the light guide body ( 110 ) is assigned an optical element ( 116 ) which has several, in particular two, separate Has lenses. 22. Sensor unit according to claim 21, characterized characterized in that the lenses merge.   23. Sensor unit according to one or more of claims 11 to 20, characterized in that in each case a transmitter ( 114 ) or receiver ( 115 ) on the light guide body ( 110 ) is assigned an optical element ( 116 ) which has a single lens. 24. Sensor unit according to claim 1, characterized in that the first sensor ( 12 ) detects the global ambient light and the second sensor ( 12 ) detects the light from a predetermined direction. 25. Sensor unit according to one or more of the preceding claims, characterized in that the sensor unit ( 10 ) is provided with a heating device which heats the integrated light guide body ( 18 , 110 ). 26. Sensor unit according to claim 25, characterized in that the heating device consists of a heating element which is in contact with the integrated light guide body ( 18 , 110 ), or is integrated in the light guide body ( 18 , 110 ). 27. Sensor unit according to claim 10, characterized characterized in that the components of the Injection molding process related to their Coefficient of thermal expansion are adjusted.