Electro-optical assembly and method for detecting ambient light

Abstract

An electro-optical assembly, in particular a sensor assembly for detecting ambient light, includes a reflection surface, a lens body and an electro-optical component, in particular a light receiver. The component includes a depression having a main lens section, in particular a diverging lens section with a concave interior wall, and a converging lens section with a convex interior wall. The interior wall of the converging lens section is formed in such a way that the rays of the ray path which travel through the converging lens section to the electro-optical component hit the reflection surface in such way that the angle of incidence at the reflection surface is larger or the same as the critical angle of the total internal reflection at the reflection surface. In another aspect a method for detecting ambient light is described.

Claims

1. Electro-optical assembly, comprising a reflection surface, a lens body and an electro-optical component, wherein the lens body includes an ambient side, a component side and a lens section, wherein a depression in the lens body extending from the component side is provided in the lens section, said depression forms together with the reflection surface in the lens section a lens for the electro-optical component, wherein the depression includes a main lens section and a converging lens section with a convex interior wall, wherein the interior wall of the converging lens section is formed in such a way that rays of a ray path travelling through the-converging lens section to the reflection surface hit the reflection surface in such way that the angle of incidence at the reflection surface is larger or equal to the critical angle of the total internal reflection at the reflection surface, and such that incident ambient light is blocked out from a predetermined angular range, as the blocked incident ambient light cannot reach the electro-optical component via the converging lens section.

2. Electro-optical assembly according to claim 1, wherein the main lens section is or comprises a diverging lens section with a concave interior wall.

3. Electro-optical assembly according to claim 1, wherein electro-optical component includes a light receiver.

4. Electro-optical assembly according to claim 1, wherein the ambient side of the lens body forms the reflection surface.

5. Electro-optical assembly according to claim 1, wherein the electro-optical assembly comprises a pane on which the lens body is mounted, wherein the side of the pane facing away from the electro-optical component forms the reflection surface.

6. Electro-optical assembly according to claim 5, wherein the pane is a windshield of a vehicle.

7. Electro-optical assembly according to claim 1, wherein the interior wall of the converging lens section is formed in such a way that the rays of the ray path, which travel via the reflection surface through the converging lens section to the electro-optical component, travel parallelly between the reflection surface and the converging lens section.

8. Electro-optical assembly according to claim 1, wherein the depression comprises an aperture towards the component side, wherein the depression extends completely within a notional cylinder, whose base area is the aperture of the depression.

9. Electro-optical assembly according to claim 8, wherein the cross-sectional areas of the depression parallel to the component side become increasingly smaller starting from the component side.

10. Electro-optical assembly according to claim 1, wherein a solid angle covered by the converging lens section is smaller than a solid angle covered by the main lens section.

11. Electro-optical assembly according to claim 1, wherein at least one of the converging lens section and the main lens section extend from the component side of the lens body.

12. Electro-optical assembly according to claim 1, wherein the transition between the main lens section and the converging lens section is abrupt.

13. Electro-optical assembly according to claim 1, wherein the depression has a vertex, wherein the electro-optical component is on a straight line that extends through the vertex and perpendicular to the component side of the lens body.

14. Electro-optical assembly according to claim 3, wherein the light receiver is on a straight line that extends through a vertex and perpendicular to the component side of the lens body.

15. Electro-optical assembly according to claim 1, wherein at least one of the component side, the ambient side and the reflection surface are parallel to each other.

16. Electro-optical assembly according to claim 1, wherein a nontransparent layer is provided on the component side at least partially.

17. Electro-optical assembly according to claim 1, wherein the lens body comprises a further lens section, wherein the converging lens section is formed at least at the point of the depression that is nearest to the additional lens section.

18. Electro-optical assembly according to claim 1, wherein electro-optical assembly comprises a housing that surrounds at least the lens body partially, wherein the housing adjoins the lens body laterally.

19. Method for detecting ambient light with the electro-optical assembly according to claim 1 comprising the following steps: detecting ambient light by means of the electro-optical assembly wherein the depression and the reflection surface interact so that incident ambient light on the electro-optical assembly is blocked out from a predetermined angular range.

20. Method according to claim 19, wherein the rays of the ray path that correspond to the blocked-out light are refracted at the depression in such a way that they are completely reflected at the reflection surface due to total internal reflection.

Description

DESCRIPTION OF THE DRAWINGS

(1) Additional features and advantages of the disclosure are found in the following description as well as the attached drawings to which reference is made. In the drawings:

(2) FIG. 1 shows the electro-optical assembly from the prior art,

(3) FIG. 2 shows an electro-optical assembly according to the disclosure schematically in section,

(4) FIG. 3 shows an enlarged view of a part of the electro-optical assembly according to the disclosure according to FIG. 2 in the area of the depression,

(5) FIG. 4 shows a schematic top view of the electro-optical assembly according to FIG. 2, and

(6) FIG. 5 shows a further embodiment of an electro-optical assembly according to the disclosure schematically in section.

DETAILED DESCRIPTION

(7) In FIG. 2, an electro-optical assembly 10 is shown comprising a lens body 12, an electro-optical component 14 and a reflection surface 16.

(8) The electro-optical component 14 can be a light source or a light receiver, for example a CMOS sensor. In the shown embodiment, the electro-optical component 14 is a light receiver for measuring incoming light on the light receiver. Thus, the electro-optical assembly becomes a sensor assembly for detecting ambient light.

(9) The lens body 12 is produced by means of injection molding from a plastic that is almost transparent in the visible range. The refractive index n.sub.1 of the material of the lens body 12 is thus larger than the refractive index n.sub.L of the air.

(10) In the shown embodiment, the lens body 12 is plate-like comprising end sides 17, a component side 18 that faces the electro-optical component 14 and an opposing ambient side 20. The component side 18 and the ambient side 20 are, for example, parallel to each other.

(11) The ambient side 20 of the lens body 12 forms the reflection surface 16 in the shown embodiment.

(12) On the end sides 17, at least the lens body 12 is tightly enclosed by a housing 22 of the electro-optical assembly 10. The housing 22 is thus nontransparent so that no light enters into the lens body 12 through the end sides 17.

(13) The lens body 12 can be coated, for example, with the material of the housing 22 in order to produce the housing 22.

(14) The lens body 12 comprises in addition a lens section 24 in which a depression 26 is formed in the lens body 12 on the component side 18.

(15) Moreover, a nontransparent layer 28 is applied to the component side 18, said nontransparent layer 28 completely covering the component side 18 except for the area of the depression 26.

(16) The nontransparent layer 28 is created, for example, through a heat-sealing method using a nontransparent film.

(17) In addition to the lens section 24, further lens sections 30 can be provided in the lens body 12, said lens sections 30 comprise additional depressions 32 on the component side 18 and/or the ambient side 20 of the lens body 12.

(18) In FIGS. 3 and 4, the depression 26 in the lens section 24 is shown enlarged. In FIG. 4, the electro-optical component 14 is shown as a dashed line and the edge of the depression 26 on the component side 18 is shown as a dotted line. The nontransparent layer 28 is indicated by the crosshatching.

(19) The depression 26 opens onto the component side 18 with an aperture 33 that has a substantially oval, elliptical or circular circumference. The aperture 33 may also have another form.

(20) The depression 26 tapers from the component side 18, i.e. that the cross-sectional areas of the depression parallel to the component side 18 become increasingly smaller starting from the component side 18.

(21) No part of the depression 26 thus extends beyond a notional cylinder that has the aperture 33 as its base area.

(22) Thus, no undercut in the lens body 12 is formed by the depression 26.

(23) Moreover, the depression ends at the vertex P which is that point that is the greatest distance perpendicular to the component side 18.

(24) The electro-optical component 14 is thus located on a straight line G that extends through the vertex P and is perpendicular to the component side 18.

(25) The depression 26 comprises a main lens section 35 and a converging lens section 36 that each both extend from the component side 18. The converging lens section 36 is thus closest to the additional lens section 30 in the shown embodiment.

(26) The main lens section 35 is designed as a diverging lens section 34 in the shown embodiment so that only the diverging lens section 34 is referred to in the following for the purpose of simplification. The embodiment design however applies likewise to a main lens section 35 that does not act as a diverging lens, but rather as a converging lens. This applies to all embodiments.

(27) Viewed from the electro-optical component 14, the converging lens section 36 covers a solid angle that is smaller than the solid angle of the diverging lens section 34. In other words, the diverging lens section 34 is larger than the converging lens section 36.

(28) For example, the ratio of the solid angle of the converging lens section 36 to the solid angle of the diverging lens section 36 is ¼ or lower.

(29) The diverging lens section 34 has an interior wall that is formed concavely. Incidentally, the interior wall of the diverging lens section 34 is a free form.

(30) In the case that the main lens section 35 acts as a converging lens, the interior wall is designed convexly and is incidentally a free form.

(31) In contrast to the diverging lens section 34, the interior wall of the converging lens section 36 is designed convexly and can otherwise also be a free form.

(32) The transition between diverging lens section 34 and converging lens section 36 is abrupt, i.e. the contour of the interior wall is not always continuously differentiable at the transition 38.

(33) Together with the reflection surface 16, the diverging lens section 34 of the depression 26 forms a lens of the lens section 24. The reflection surface 16 and the interior wall of the depression 26 are to this end the refracting surfaces of this lens.

(34) A diverging lens is thus formed by the diverging lens section 34 and the reflection surface 16, said diverging lens refracts ambient light that is incident across a wide angular range on the ambient side 20 to the electro-optical component 14.

(35) The ray path of all rays that hit the electro-optical component 14, thus here the light receiver, is drawn in FIG. 2. This ray path is identical to a ray path that forms when the electro-optical component 14 is a light source.

(36) Rays of the ambient light S.sub.U are refracted first on the reflection surface 16, thus on the ambient side 20 of the lens body 12, and travel towards the depression 26.

(37) The ambient light S.sub.U travels then towards the diverging lens section 34 and is refracted there again in such a way that the ambient light S.sub.U completely falls on the electro-optical component 14.

(38) The interior wall of the diverging lens section 34 can be spherical in order to collect the ambient light S.sub.U uniformly. In the shown embodiment, the diverging lens section 34 is however a free form that has be selected in such a way that the ambient light S.sub.U is captured more from certain angular ranges.

(39) In addition to the rays of the ambient light S.sub.U, the ray path also comprises the rays S.sub.A that travel through the converging lens section 36 of the depression 26 and are regarded as blocked out rays S.sub.A.

(40) The blocked-out rays S.sub.A travel between the lens body 12 and the electro-optical component 14 in the solid angle that is to be blocked out.

(41) Viewed from the electro-optical component 14, the blocked-out rays S.sub.A travel on the converging lens section 36 and are refracted by the converging lens section 36 in such a way that they fall on the reflection surface 16 flatly.

(42) The form of the converging lens section 36 can be selected in such a way that the rays S.sub.A in the lens body 12 travel parallelly after they have passed through the converging lens section 36.

(43) The blocked-out rays S.sub.A now hit the reflection surface 16 at an angle of incidence α, wherein the angle of incidence α is defined as the angle between the ray S.sub.A and the perpendicular to the reflection surface 16.

(44) The angle of incidence α is greater or the same as the critical angle θ.sub.c of the total internal reflection at the reflection surface 16, wherein the boundary surface for the total internal reflection is the interface between air and the material of the lens body 12. The critical angle θ.sub.c arises from the following known formula:

(45) ${\theta }_c=\arcsin \left(\frac{n_L}{n_1}\right)$

(46) To this end, n.sub.1 is the refractive index of the material of the lens body 12 and n.sub.L the refractive index of air.

(47) As the angle of incidence α is greater or the same as the critical angle θ.sub.c of the total internal reflection, the blocked-out rays S.sub.A are reflected completely at the reflection surface 16 and do not leave the lens body 12.

(48) Rays, which are not drawn in FIG. 2, are prevented by the nontransparent layer 28 from reaching the component 14.

(49) Thus, there are no rays that lead to the electro-optical component 14 from the angular range W that is to be blocked out and is drawn with dashed lines in FIG. 2. Consequently, the angular range W is blocked out.

(50) Thus, the reflection surface 16 and the converging lens section 36 of the depression 26 interact in such a way that light from a predetermined angular range W, which is to be blocked out, does not reach the electro-optical component 14.

(51) In FIG. 5, a second embodiment of an electro-optical assembly 10 according to the disclosure is shown that substantially corresponds to the electro-optical assembly 10 of the first embodiment. Therefore, only the differences are discussed hereinafter and the same parts and parts with the same function are provided with the same reference signs.

(52) The electro-optical assembly 10 of the second embodiment comprises a pane 42 that may be, for example, a windshield or another pane of the vehicle.

(53) The pane 42 has an exterior side 46 and an interior side 48, on which the lens body 12 is attached with its ambient side 20.

(54) In the shown embodiment, the attachment occurs by means of a transparent silicone layer 44 that is provided between the pane 42 and the ambient side 20 of the lens body 12.

(55) In this second embodiment, the reflection surface 16 is not formed by the ambient side 20 of the lens body 12, but rather by the exterior side 46 of the pane 42 facing away from the electro-optical component 14.

(56) Accordingly, the boundary surface of the total internal reflection is now the interface between the material of the pane 42 and air. If the refractive index of the material of the pane 42 differs from the refractive index of the material of the lens body 12, this results in, compared to the first embodiment, another critical angle θ.sub.c of the total internal reflection. The critical angle is now:

(57) ${\theta }_c=\arcsin \left(\frac{n_L}{n_2}\right),$

(58) wherein n.sub.2 is the refractive index of the material of the pane 42 and n.sub.2>n.sub.L applies.

(59) Even in this case, the form of the converging lens section 36 is selected in a such a way that the blocked-out rays S.sub.A travel through the converging lens section 36 and are reflected completely at the reflection surface 16, here therefore the exterior side 46 of the pane 42.

(60) In both embodiments, in particular however in the second embodiment, it is conceivable that the reflection surface 16, thus the ambient side 20 of the lens body 12 and/or the exterior side 46 of the pane 42, is curved. This curvature can also be taken into account by the form of the converging lens section 36 to such effect that a total internal reflection of the blocked-out rays S.sub.A occurs nevertheless on each point of the reflection surface 16. Thus, a curvature does not constitute a problem in principle, but rather only a problem of the precise calculation and production of the converging lens section 36 of the lens body 12.

(61) For this reason, it is useful to select the angle of incidence α considerably larger than the critical angle θ.sub.c in order to be able to compensate for a certain degree of inaccuracies due to production tolerances.