DE102009028468A1 - Light sensor arrangement for sensor unit of ambient light sensor of motor vehicle, has light conductor element for guiding light beam bundles coupled at carrier element to output areas such that bundles are directed to sensor elements - Google Patents

Abstract

The arrangement (10) has a detection area (15) with two sensor elements (19, 21) arranged at a distance to each other for detecting intensity of light beam bundles (L1, L2). A light conductor element (14) guides the light beam bundles coupled at a carrier element (7) at the detection area to output areas (18, 20) such that the light beam bundles are directed to the sensor elements respectively. The light conductor element has a reflection surface at one of the output areas for reflecting one of the light beam bundles to the other output area.

Description

Technical area

The The invention relates to ambient light sensors for motor vehicles, in particular Ambient light sensors that use multiple light sensors for directed Have light and integrated in an ambient light sensor are formed. The invention further relates to devices to recognize the strength the backlight for a head-up display.

State of the art

Especially in conjunction with optical rain sensors are used in motor vehicles Ambient light sensors used which the intensity or brightness of the ambient light and thereby the on and off behavior automatically controlled by headlamps. The ambient light sensors usually include a global light sensor to substantially the intensity of the To detect ambient light incident from above and under a large incident angle range. The Ambient light sensors further comprise a directional light sensor, which is designed to be in a forward (i.e., forward) direction directed direction in a narrow angular range substantially Parallel to the road level (horizontal) with high sensitivity the incidence of light to detect local darkening, e.g. B. by tunnel or Bridges, to recognize. An essential property of the directional light sensor is to detect light strongly directionally selective. This should be therefore for to be as insensitive as possible to light from other angles.

Farther are increasingly used head-up displays in which a display projection with Vehicle information at eye level the driver is projected into the windshield. The brightness The display projection should be set automatically so that both the clear view through the windshield to be driven Distance as well as a sufficient contrast between the display projection and the background of the display projection.

Around always set the brightness of the display projection so that this is recognizable by the driver, but not the unobstructed view obstructed to the front, the brightness of the display projection depends on the background brightness are set. The background brightness corresponds to the brightness of the roadway section through the Line of sight between the driver's eyes and the display projection is defined on the windshield. This is the direction in the intensity of directed from the roadway section to the driver's eyes Beams of light is determined by the position of the driver's head and defines the position of the display projection directed downwards. The head-up display light sensors for head-up displays are in usually formed with separate from the ambient light sensor light sensors.

For example should such a head-up display light sensor for a head-up display function a Have direction of maximum sensitivity, which compared to the Horizontal (horizontal) by 5 to 10 °, in particular 7 °, in the direction the road is inclined. The sensitivity should be in the range of ± 3 ° to ± 5 °, in particular at ± 4 ° to below 50% fall off. Still below the horizontal is the sensitivity Head-Up Display Light Sensor Head-Up Display Near 0% dropped. The formation of the head-up display light sensor as separate component in addition to an already provided ambient light sensor for controlling the turn-on and turn-off behavior of headlamps an elevated one Expense.

It is therefore an object of the present invention, a combined Light sensor available too which, according to both Function of an ambient light sensor an indication of the light intensity in horizontal Direction (parallel to the road) and an indication of the Light intensity from a direction inclined downwards to the horizontal direction (towards the lane section, which is the background of the head-up display represents) without the indication of the light intensity from the downwards inclined direction by a light incidence of horizontal or is directed upward direction.

Disclosure of the invention

These The object is achieved by the light sensor arrangement for a motor vehicle according to claim 1 and by the sensor unit according to the independent claim solved.

Further advantageous embodiments are specified in the dependent claims.

• – mindestens zwei versetzt zueinander angeordnete Sensorelemente zum Detektieren einer Intensität eines jeweiligen Lichtstrahlenbündels;
• – ein Lichtleiterelement, um ein erstes der Lichtstrahlenbündel und ein zweites der Lichtstrahlenbündel, die in das Trägerelement an dem Detektionsbereich eingekoppelt werden, zu einem oder mehreren Austrittsbereichen zu führen, so dass das erste Lichtstrahlenbündel auf eines der Sensorelemente und das zweite Lichtstrahlenbündel auf ein weiteres der Sensorelemente gerichtet wird.

According to a first aspect, a light sensor arrangement is provided for attachment to an optically transparent carrier element, in particular a windshield, with a detection area. The light sensor arrangement comprises:

• - At least two mutually offset sensor elements for detecting an intensity of a respective light beam;
• A light guide element to connect a first one of the light beams and a second one of the light beams which are coupled into the support element at the detection area to one or more of the light beams to lead multiple exit areas, so that the first light beam is directed to one of the sensor elements and the second light beam to another of the sensor elements.

A The idea of the present invention is to provide light beams which from two different directions at a very acute angle arrive at the detection area in the light sensor arrangement to couple and lead there that these can be directed to different sensor elements, wherein an almost complete one Separation of the light beams should be achieved.

Farther For example, the optical waveguide element may be configured to surround the first light beam and the second light beams to lead to different separate exit areas.

Especially For example, the light guide element can be designed to contact the second light beam to decouple one of the exit areas, wherein the light guide element has a reflection surface at one of the exit regions, around the first ray of light to reflect on another of the exit areas and there decouple. The one exit area can thus with respect to Light beam be inclined that the second light beam at the one exit area is coupled out and the first light beam at the one exit area is totally reflected.

Accordingly, the Separating done so that one of the light beams a position and / or in one direction of an optical waveguide is decoupled while the other light beam in the optical waveguide is totally reflected at least once and an exit region other than the first light beam has from the optical waveguide. This allows light beams, the from very close to each other directions on the detection area come in, decouple at different areas of the optical waveguide, so that a very good separation of the individual light beams takes place and so the intensity the light beam through separate light sensors can be selectively detected.

The The optical waveguide element can furthermore be designed to be the first Light beam and the second light beam to lead to a common exit region, wherein the light beams on the common exit area are guided in different directions, so that these are coupled out in different directions, so that the light beams be directed to mutually offset sensor elements.

Of the common exit region can with respect to the light beam so be inclined that the light beams at the exit areas be decoupled in different directions, so this fall on the respective sensor element.

According to one embodiment can one or more apertures provided between the exit areas be. Furthermore you can Apertures for limiting the detection area and for separating the Light ray components at the transition be provided from the windshield to the light guide element, in particular, the light beams of light rays directed onto the light sensor units to separate the ambient light.

Farther can one or more further diaphragms on a surface of the light guide element be arranged over the light beams be coupled into the light guide element, wherein the other Aperture separate openings for the first and the second light beam define.

According to one Another aspect is a sensor unit with the above light sensor arrangement and provided with an optically transparent support member on which the light sensor assembly is mounted to transmit the light beams across the Detection area of the support element couple into the light guide element.

According to one Another aspect is provided, the above light sensor arrangement in an ambient light sensor, wherein the ambient light sensor intensities of at least two directed light beams detected to an indication for one Light intensity of the first light beam from a lane-parallel direction of a headlight control unit and an indication for a light intensity of the second light beam a head-up display control unit available to deliver.

Brief description of the drawings

preferred embodiments will be explained in more detail with reference to the accompanying drawings. It demonstrate:

1 a schematic representation of a motor vehicle with a head-up display and an ambient light sensor;

2 a schematic representation of a light sensor arrangement on a windshield of the motor vehicle with an optical waveguide for splitting light beams from different directions;

3 a schematic representation of another embodiment of a light sensor assembly for a windshield of a motor vehicle, in which the light sensors are arranged to each other in the vertical direction with respect to a roadway;

4 a schematic representation of another embodiment of a combined light sensor for the detection of the intensity of the ambient light for the rain sensor of the ambient light for the control of the headlight function and a light sensor for the detection of the background light intensity for a head-up display function.

Description of embodiments

1 shows a schematic representation of a motor vehicle 1 on a roadway 2 , The car 1 includes an ambient light sensor 3 and a head-up display unit 4 ,

The ambient light sensor 3 is on a windshield 7 of the motor vehicle 1 attached and with an automatic headlight control unit 5 connected. The ambient light sensor 3 is designed to provide an indication of the intensity (brightness, light intensity) of an incident from above (perpendicular to the road surface of the motor vehicle) ambient light and an indication of the intensity of light rays from a horizontal direction, ie parallel to the road in the forward direction of the motor vehicle 1 come to mind. The incident from the forward direction of light beams should be detected only in a limited angular range. Depending on the information about the intensity of the ambient light and the light intensity of the incident from the forward direction of light beams, for example, headlights of the motor vehicle 1 through the headlight control unit 5 controlled.

The head-up display unit 4 is in an interior 6 of the motor vehicle 1 arranged and serves a vehicle information shown as an image on an inner surface of the windshield 7 of the motor vehicle 1 to project. The vehicle information may include information that requires the driver of the vehicle during the trip required 1 submit, for. B. an indication of the driving speed. The position of this display projection on the windshield 7 is generally positioned below the lane parallel line of sight of the driver, so that one ahead of the lane section serves as the background for the display projection.

The ambient light sensor 3 is generally a light sensor arrangement 10 formed, which additionally performs the function of detecting the light intensity of incident from the roadway section B light rays.

2 shows a schematic representation of an embodiment of such a light sensor arrangement 10 attached to the windshield 7 of the motor vehicle 1 is appropriate. The windshield 7 serves as a carrier element. Due to the design of the motor vehicle 1 and the arrangement of the windshield 7 is the windshield 7 concerning the roadway 2 arranged substantially at a constant angle. In this case, short-term fluctuations due to driving over uneven road are not taken into account.

On an inner surface of the windshield 7 is as part of the light sensor arrangement 10 a light guide element 14 arranged. The light guide element 14 is suitable to light that through the windshield 7 in the light guide element 14 coupled, to conduct and decouple at defined exit areas. The light guide element 14 is preferably with the windshield 7 so connected, so that at the junction no total reflection or other interruption of the incident light beams takes place. Preferably, the refractive index of the light guide element 14 same as the windshield 7 , making a straight-lined course on the windshield 7 incident light rays through the windshield 7 and the light guide element 14 consists.

The present light sensor arrangement 10 has a detection area 15 on, on the light beams from all directions, in particular a first light beam L ₁ from a direction parallel to the road surface and a second light beam L ₂ from a relative thereto inclined downward direction. In particular, the second light beam L ₂ hits the detection area from one direction 15 the windshield 7 which are defined by the connecting lines between the lane section B and the eyes of the driver. Depending on the incident of the carriageway section B light intensity, ie the light intensity of the second light beam L2, the head-up display unit 4 the light intensity of the display projection for the vehicle information on the inside of the windshield 7 Taxes.

The intensity of the first light beam L ₁ represents a size z. B. as described above in the use of an automatic control of an on and off behavior of a headlamp is used. For example, the intensity of the first light beam L ₁ can be evaluated to detect a tunnel or a bridge, so that already during or before immersion in the shadow of the tunnel or the bridge the light is switched on. The two functions described above can be achieved by the light sensor arrangement 10 realize.

For this purpose, the second light beam L ₂ , which at an angle to the detection area 15 the windshield 7 impinges, with respect to the horizontal light beam L ₁ in the direction of the road 2 is inclined through the windshield 7 in the light guide element 14 directed, wherein it is provided that the second light beam L ₂ at a first exit surface 18 from the light guide 14 is coupled out, so that the second light beam L ₂ to a first light sensor 19 incident.

The roadway parallel incident light beams (light beams L ₁ ) are in the windshield 7 and in the light guide element 14 also on the first exit area 18 directed. The first exit area 18 is with respect to the course of the light beams to be detected L ₁ , L ₂ inclined so that the angle of incidence of the first light beam L ₁ , with respect to a surface normal of the first exit region 18 is defined on the first exit area 18 is greater than the angle of incidence of the second light beam L ₂ .

The light guide element 14 can be designed so that the first exit area 18 is designed at an angle with respect to the first light beam L ₁ and the second light beam L ₂ , so that the first light beam L ₁ at an angle to the first exit region 18 which is greater than the critical angle of total reflection, and the second light beam L ₂ impinges at an angle which is smaller than the critical angle of total reflection. The first light beam L ₁ is thus at the first exit region 18 totally reflected and continues through the light guide element 14 to a second exit area 20 where the first light beam L ₁ emerges and a second light sensor 21 incident. The critical angle of the total reflection results from the different refractive indices of the material of the light guide element 14 and the ambient air. Of course, the light guide element 14 also be designed so that the first exit area 18 is designed at an angle with respect to the first light beam L ₁ and the second light beam L ₂ , so that the first light beam L ₁ at an angle to the first exit region 18 incident, which is smaller than the critical angle of total reflection, and the second light beam L ₂ impinges at an angle which is greater than the critical angle of total reflection.

The first exit area 18 may preferably be oriented so that the angles of incidence of the first light beam L ₁ and the second light beam L _{2 have} the same distance from the critical angle of total reflection. That is, when, for example, the angles of incidence of the light beams L ₁ and L ₂ at the detection area 15 differ by 7 °, the angle of incidence of the first light beam L ₁ on the first exit area 18 by 3.5 ° greater than the critical angle of total reflection and the angle of incidence of the second light beam L ₂ on the first exit region 18 3.5 ° smaller than the critical angle of total reflection.

By the light sensor arrangement described above 10 it is possible, the first light beam L ₁ to the second light sensor 21 and the second light beam L ₂ on the first light sensor 19 so that the intensities of the light beams from the different directions can be detected discriminated from each other.

In the embodiment of the 2 are the first and the second light sensor 19 . 21 on a circuit board 22 arranged, which is arranged approximately horizontally, ie parallel to the road.

3 shows a light sensor arrangement 10 according to a further embodiment of the invention. In contrast to the embodiment of 2 has the light guide element 14 no second exit surface, but the incident light beams L ₁ and L ₂ are through the windshield 7 and through the light guide element 14 guided and on a common outlet region or two mutually slightly offset, preferably adjacent exit regions 24 . 27 directed. At the exit areas 24 . 27 Both light beams L ₁ and L _{2 are} coupled out. The angles at which the light beams L ₁ and L ₂ on the exit areas 24 . 27 are incident, are different, so that the exit angle by refraction of the light beams L ₁ and L ₂ at the interface between the light guide element 14 and the surrounding medium and thus the second light beam L ₂ to the first light sensor 19 and the first light beam L ₁ on the second light sensor 21 be directed. The exit areas 24 . 27 may be flat, coplanar and / or merge into each other, and have a predetermined same inclination angle with respect to the roadway. In other words, the incident only with a small angular difference light beam L ₁ , L ₂ are broken so that after the exit of the light beam L ₁ , L ₂ from the light guide element 14 these have a greater angular difference from one another.

Due to the staggered arrangement of the first and second light sensor 19 . 21 on a circuit board 22 The angles of incidence are defined as incident light rays at different angles of incidence on the detection area 15 the windshield 7 so through the light guide element 14 be directed to the common exit surface 24 hit at an angle at which the light rays to different areas outside the light sensors 19 . 21 be directed. Thus, a very good resolution and separation of the detection of the light intensities of the incident light beams L ₁ and L _{2 can be} obtained.

in the shown embodiment the board can be arranged perpendicular to the road parallel direction be.

In 4 is another embodiment of the light sensor arrangement 10 shown. The embodiment of the 4 based on the 3 , wherein the light sensor arrangement 10 additionally an ambient light sensor 25 in particular to detect a light intensity of the incident from above (perpendicular to the road surface) ambient light. The ambient light is over the detection area 15 taken and through the light guide element 14 directed and at a suitable further exit area 27 that of the exit areas 24 . 27 is different for the first and second light beams L1, L2, by a collecting lens structure 26 of the light guide element 14 collected and, preferably, focused on the ambient light sensor 25 directed. The collection lens structure allows light rays of as wide an angular range as possible to be incident on the ambient light sensor 25 can be directed.

In order to achieve a better separation of the directed light beams L ₁ , L ₂ , it may be provided to use suitable diaphragms ( 29 ) between the exit areas. Furthermore, diaphragms ( 30 ) for limiting the detection area 15 and for separating the light beam components at the transition from the windshield 7 to the light guide element 14 be provided in particular to the light sensor units 19 . 21 directed light beams L ₁ and L ₂ of light rays of the ambient light to separate.

Claims (10)

Light sensor arrangement ( 10 ) for attachment to an optically transparent support element ( 7 ), in particular a windshield, with a detection area ( 15 ), comprising: - at least two mutually offset sensor elements ( 19 . 21 ) for detecting an intensity of a respective light beam; A light guide element ( 14 ), a first of the light beams (L ₁ ) and a second of the light beams (L ₂ ), which in the carrier element ( 7 ) at the detection area ( 15 ) are coupled to one or more exit areas ( 18 . 20 ), so that the first light beam (L ₁ ) on one of the sensor elements ( 19 . 21 ) and the second light beam (L ₂ ) on another of the sensor elements ( 19 . 21 ). Light sensor arrangement ( 10 ) according to claim 1, wherein the light guide element ( 14 ) is formed around the first light beam (L ₁ ) and the second light beam (L ₂ ) to different separate exit regions ( 19 . 21 ) respectively. Light sensor arrangement ( 10 ) according to claim 2, wherein the light guide element ( 14 ) is formed to the second light beam (L ₂ ) at one of the exit regions ( 18 . 20 ), wherein the light guide element ( 14 ) at one of the exit areas ( 18 . 20 ) has a reflection surface to the first light beam (L ₁ ) on another of the exit regions ( 18 . 20 ) to reflect and decouple there. Light sensor arrangement ( 10 ) according to claim 3, wherein said one exit region ( 18 . 20 ) is inclined with respect to the light beams (L ₁ , L ₂ ) so that the second light beam (L ₂ ) at the one exit region ( 18 . 20 ) and the first light beam (L ₁ ) at the one exit region ( 18 . 20 ) is totally reflected. Light sensor arrangement ( 10 ) according to claim 1, wherein the light guide element ( 14 ) is formed to the first light beam (L ₁ ) and the second light beam (L ₂ ) on a common exit region ( 24 . 27 ), wherein the light beams (L ₁ , L ₂ ) are guided onto the common exit area in different directions, so that they are coupled out in different directions, so that the light beams (L ₁ , L ₂ ) on mutually offset sensor elements ( 19 . 21 ). Light sensor arrangement ( 10 ) according to claim 5, wherein the common exit area ( 24 . 27 ) with respect to the light beams (L ₁ , L ₂ ) is inclined so that the light beams (L ₁ , L ₂ ) at the exit areas ( 14 . 27 ) are coupled out in different directions, so that they are applied to the respective sensor element ( 19 . 21 ) fall. Light sensor arrangement ( 10 ) according to one of claims 2 to 4, wherein one or more diaphragms ( 29 ) between the exit areas ( 24 . 27 ) are provided. Light sensor arrangement ( 10 ) according to one of claims 1 to 7, wherein one or more further diaphragms ( 30 ) on a surface of the light guide element ( 14 ) are arranged, via which the light beam (L ₁ , L ₂ ) in the light guide element ( 14 ), wherein the further diaphragms ( 30 ) from each other define separate openings for the first and second light beams (L ₁ , L ₂ ). Sensor unit ( 19 . 20 ) with a light sensor arrangement according to one of claims 1 to 8 and with an optically transparent support element ( 7 ), to which the light sensor arrangement ( 10 ) is mounted to the light beam (L ₁ , L ₂ ) over the detection area ( 15 ) of the carrier element ( 7 ) in the light guide element ( 14 ). Use of the light sensor arrangement ( 10 ) according to any one of claims 1 to 8 in an ambient light sensor, wherein the ambient light sensor detects intensities of at least two directional light beams (L ₁ , L ₂ ) to provide an indication of a light intensity of the first light beam (L ₁ ) from a direction parallel to a headlight control unit provide an indication of a light intensity of the second light beam (L ₂ ) of a head-up display control unit available.

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