OPTICAL SENSOR DEVICE

Abstract

An optical sensor device comprises a first and a second optical sensor arrangement. In the first optical sensor arrangement at least one optical sensor structure measures the incidence angle of incoming light that is approximately on the main beam axis of a light source. The second optical sensor arrangement comprises at least one optical sensor structure with at least one optical sensor, at least two metal layers and opaque walls optically isolating the optical sensor. An evaluation circuit provides an output signal of the second optical sensor arrangement under the condition that the incidence angle measured by the first optical sensor arrangement lies within a set interval.

Claims

1. An optical sensor device, comprising: a first optical sensor arrangement including at least one optical sensor structure, measuring the incidence angle of incoming light () that is approximately on the main beam axis of a light source; a second optical sensor arrangement comprising at least one optical sensor structure having at least one optical sensor with a light-sensitive surface, a metal layer structure forming an aperture above the optical sensor including at least two metal layers, one in or above the plane of the optical sensor and the other one stacked further above, and opaque walls connecting the metal layers and optically isolating the optical sensor; and an evaluation circuit which is connected to outputs of the first and the second optical sensor arrangement and which provides an output signal of the second optical sensor arrangement under the condition that the incidence angle measured by the first optical sensor arrangement lies within a set interval.

2. The optical sensor device according to claim 1, wherein the first optical sensor arrangement comprises the at least one optical sensor structure, having at least one optical sensor with a light-sensitive surface, a metal layer structure forming an aperture above the optical sensor including at least two metal layers, one in or above the plane of the optical sensor and the other one stacked further above, and opaque walls connecting the metal layers and optically isolating the optical sensor and at least three further optical sensor structures with the at least three further optical sensor structures being directional such that light incident from at least three different directions can be detected, especially light with incidence angles different from 90 towards the plane of the light-sensitive surface, such that the angle between the main beam axis of the light source and the normal of the light-sensitive surface is measured.

3. The optical sensor device according to claim 2, wherein the first optical sensor arrangement includes the at least one optical sensor structure, with its light-sensitive surface being oriented perpendicular towards the main beam axis of the light source or deviating from this orientation by a given range and wherein the evaluation circuit displays a ratio of the signal detected by the at least three directional optical sensor structures in the first optical sensor arrangement to the signal detected by the at least one optical sensor structure in the first optical sensor arrangement, which is referred to as the haze index.

4. The optical sensor device according to claim 1, wherein the first optical sensor arrangement includes the at least one optical sensor structure and at least one further optical sensor structure, both having at least one optical sensor with a light-sensitive surface, a metal layer structure forming an aperture above the optical sensor including at least two metal layers, one in or above the plane of the optical sensor and the other one stacked further above, opaque walls connecting the metal layers optically isolating the optical sensor and the further optical sensor structure additionally having an opaque layer blocking light that is incident perpendicular towards the light-sensitive surface; such that the optical sensor structure detects direct light and the further optical sensor structure detects ambient light, and wherein the haze index is determined by a ratio of the output signals of these two optical sensor structures.

5. The optical sensor device according to claim 4, wherein the evaluation circuit provides the output signal of the second optical sensor arrangement under the condition that the output signal of the optical sensor structure detecting direct light reaches a maximum value and that the output signal of the optical sensor structure detecting ambient light reaches a minimum value.

6. The optical sensor device according to claim 3, wherein the output signal of the second optical sensor arrangement is corrected according to the measured haze index.

7. The optical device according to claim 4, wherein the optical sensor structures that detect direct and ambient light contain color filters above the aperture which is above the light-sensitive surface; and wherein the color correlated temperature of the incident light is determined.

8. The optical sensor device according to claim 7, wherein the evaluation circuit provides the output signal of the second optical sensor arrangement under the condition that the measured color correlated temperature is within a set range.

9. The optical sensor device according to claim 1, wherein the incidence angle of the incoming light measured by the first optical sensor arrangement is displayed by the evaluation circuit.

10. The optical sensor device according to claim 1, wherein the range for valid values of the output signal of the first optical sensor arrangement can be set.

11. The optical sensor device according to claim 1, wherein the optical sensor structures in the first and/or the second optical sensor arrangement are shaped hexagonally and are arranged in a honeycomb structure.

12. The optical sensor device according to claim 1, wherein in the first optical sensor arrangement the at least one optical sensor structure is covered with an infra-red blocking filter.

13. The optical sensor device according to claim 1, wherein in the second optical sensor arrangement the at least one optical sensor structure is covered with an ultra-violet pass filter.

Description

[0037] The following description of figures may further illustrate and explain exemplary embodiments. Components that are functionally identical or have an identical effect are denoted by identical references. Identical or effectively identical components might be described only with respect to the figures where they occur first. Their description is not necessarily repeated in successive figures.

[0038] FIG. 1 shows an exemplary embodiment of the optical sensor device;

[0039] FIG. 2A and 2B show the incidence of direct and ambient sunlight onto the detector aperture;

[0040] FIGS. 3A to 3C show the setup of examples of different optical sensor structures;

[0041] FIG. 4 shows an exemplary embodiment of an optical sensor arrangement that measures the haze index including three directional sensors;

[0042] FIG. 5 shows the angular field of view of four directional sensors and one sensor that detects direct light;

[0043] FIG. 6 shows experimental results of an exemplary embodiment that measures the incidence angle;

[0044] FIG. 7A shows the setup of an exemplary embodiment providing the haze index;

[0045] FIG. 7B shows simulation results for an exemplary embodiment providing the haze index;

[0046] FIG. 8A to 8C show exemplary embodiments with color filters and arrangements of the optical sensor structures; and

[0047] FIGS. 9A and 9B show exemplary embodiments with four and eight directional optical sensor structures, respectively.

[0048] FIG. 1 shows an embodiment of an optical sensor device 1 that detects directional and non-directional light. A first optical sensor arrangement 10 includes at least one optical sensor structure 11. The first optical sensor arrangement 10 detects incident light 12. An output 13 of the first optical sensor arrangement 10 is connected to an evaluation circuit 14. A second optical sensor arrangement 15 includes at least one optical sensor structure 16. The second optical sensor arrangement 15 detects incident light 12. The second optical sensor arrangement 15 has an output 17 which is connected to the evaluation circuit 14 and provides an output signal 46.

[0049] The evaluation circuit 14 has at least two outputs 18 and 19. The output 18 provides the output signal 46 of the second optical sensor arrangement 15. The first optical sensor arrangement 10 measures the incidence angle of incoming light 12 that is approximately on the main beam axis 20 of a light source 22. The output 19 of the evaluation circuit 14 provides the incidence angle measured by the first optical sensor arrangement 10. By an input 21 of the evaluation circuit 14 a range for allowed values of the incidence angle is set. The evaluation circuit 14 provides the output signal 46 of the second optical sensor arrangement 15 under the condition that the measured incidence angle is within the set range. The output 19 of the evaluation circuit 14 provides the measured incidence angle so that the orientation of the optical sensor device 1 can be changed in such a way that the measured incidence angle is within the given range.

[0050] FIGS. 2A and 2B show the optical sensor device 1 and a light source 22 which, for example, can be the sun, as shown in this case. FIG. 2A shows the case of a clear day. Most of the sunlight is not scattered and reaches a detector aperture 23 directly. At the detector aperture 23 the angular spread of direct sunlight 34 amounts to 0.5. Under these weather conditions only about 10% of the solar radiation is scattered. Scattered or ambient light 35 reaches the detector aperture 23 from different angles. FIG. 2B shows the case of a cloudy or overcast day. Almost no direct light 34 reaches the detector aperture 23. Most of the light that reaches the detector aperture is scattered.

[0051] FIG. 3A shows an exemplary embodiment of the optical sensor structure 16 of the second optical sensor arrangement 15. The optical sensor structure 16 comprises an optical sensor 24, at least two metal layers 43 and 44 and an aperture 25. In one embodiment the optical sensor structure 16 comprises three metal layers 43, 44 and 45. Vias or other connectors 26 may connect the metal layers and optically isolate the optical sensor 24. The aperture 25 defines an angular field of view of the optical sensor 24 with an opening angle of . In a preferred embodiment the optical sensor 24 is an ultra-violet light sensor.

[0052] FIG. 3B shows one embodiment of the optical sensor structure 11 of the first optical sensor arrangement 10. The setup is the same as for the optical sensor structure 16 of the second optical sensor arrangement 15. In an alternative embodiment the optical sensor 24 in the optical sensor structure 11 is covered with an infrared blocking filter.

[0053] FIG. 3C shows one embodiment of a second optical sensor structure 27 in the first optical sensor arrangement 10. It also comprises the same setup as the optical sensor structure 16 with the only difference that in the plane of the topmost metal layer 44 there is another metal layer 28 that blocks light that is incident perpendicular towards the optical sensor 24. With this, light incident from directions that are not perpendicular towards the optical sensor 24 are detected. In an alternative embodiment the optical sensor 24 in the optical sensor structure 27 is covered with an infrared filter.

[0054] FIG. 4 shows one embodiment of the optical sensor arrangement 10 that measures the incidence angle of direct incident light towards the normal of the optical sensor 24. Three directional sensors 29, 30 and 31 detect light that is incident from different directions but not perpendicular towards the optical sensors. The optical sensor structure 11 detects light that is incident perpendicular towards its light-sensitive surface 32. With this arrangement the incidence angle of direct light can be determined.

[0055] FIG. 5 shows angular fields of view 37, 38, 39 and 40 for four different directional sensors. The four directional sensors are referred to as north, south, east and west and they detect incoming light from four different directions. Also the angular field of view 36 of a sensor detecting the direct light is shown, which is defined by the opening angle of an optical sensor.

[0056] FIG. 6 shows experimental results for an optical sensor device including two directional sensors referred to as N and S. The incidence angle .sub.NS is plotted over the ratio NS/N+S of the signals of the two directional sensors. In a range of +/20 the ratio shows a linear shape. The dotted line represents the fitted function y. The offset of 1.5 is due to a measurement artefact. With this it is shown that within a certain range the incidence angle .sub.NS of the incident light can be determined. A measurement for the two other directional sensors, E and W, shows a similar behaviour. With this, the two angles .sub.NS and .sub.EW necessary for the calculation of can be estimated.

[0057] FIG. 7A shows a haze detector employing two optical sensor structures. One optical sensor structure 11 has an aperture 25 such that light is detected which is incident perpendicular towards the light-sensitive surface 32 of the optical sensor 24. The second optical sensor structure 27 detects ambient light incident from different directions. In this embodiment both optical sensor structures are shaped hexagonally.

[0058] FIG. 7B shows simulation results for the haze detector depicted in FIG. 7A. On the y-axis different ratios of simulated ambient/direct light power are plotted over the ratio of the signals of the optical sensor structure 27 that detects ambient light and the optical sensor structure 11 that detects direct light on the x-axis. This means that for different light conditions the signal of the haze detector is detected which means the ratio of ambient light towards direct light is measured. The dotted line is a logarithmic fit to the simulated data. Therefore, with the haze index detected by the haze detector the ratio of ambient towards direct light can be estimated.

[0059] FIG. 8A shows the optical sensor structure 16 which detects preferably ultra-violet light. According to one embodiment several of these optical sensor structures 16 are arranged in a square lattice where the optical sensor structures are square-shaped. An alternative embodiment is to arrange the optical sensor structures 16 in a honeycomb structure where the optical sensor structures are shaped hexagonally.

[0060] FIG. 8B shows an optical sensor structure 11. In one embodiment a color filter 33 is arranged on top of the aperture 25. By employing different color filters the color-correlated temperature can be determined. In one embodiment the optical sensor structure 11 is shaped hexagonally and several optical sensor structures 11 are arranged in a honeycomb structure array. In one embodiment six optical sensor structures 41 in this array comprise color filters on top of the aperture 25 and one optical sensor structure 42 does not comprise any color filter on top of its aperture. With this, the area of the optical sensor structure 42 without a color filter is smaller than the areas of the optical sensor structures 41 with a color filter such that a saturation of the optical sensor structure 41 is prevented because its area is smaller.

[0061] FIG. 8C shows the same setup as in FIG. 8B for an optical sensor structure 27 of the first optical sensor arrangement 10. With this, the color-correlated temperature can also be determined from ambient light.

[0062] FIG. 9A shows a preferred embodiment of the first optical sensor structure 10. Four directional sensor structures 29, 30, 31 and 46 detect ambient light from four different directions. One optical sensor structure 11 detects light that is perpendicular towards the light-sensitive surface 32 of the optical sensor 24. With this optical sensor arrangement the incidence angle of direct incident light can be determined and also the haze index.

[0063] FIG. 9B shows another embodiment of the optical sensor arrangement depicted in FIG. 9A where, instead of four directional sensors, eight directional sensors 29 are employed and detect ambient light incident from eight different directions.

LIST OF REFERENCE NUMERALS

[0064] 1: optical sensor device [0065] 10: first optical sensor arrangement [0066] 11: optical sensor structure [0067] 12: incident light [0068] 13: output [0069] 14: evaluation circuit [0070] 15: second optical sensor arrangement [0071] 16: optical sensor structure [0072] 17: output [0073] 18: output [0074] 19: output [0075] 20: main beam axis of light source [0076] 21: input to set range of incidence angle [0077] 22: light source [0078] 23: detector aperture [0079] 24: optical sensor [0080] 25: aperture [0081] 26: opaque walls [0082] 27: second optical sensor structure [0083] 28: opaque layer blocking direct light [0084] 29,30,31,46: directional optical sensor structures [0085] 32: light-sensitive surface [0086] 33: color filter [0087] 34: direct light [0088] 35: ambient light [0089] 36: angular field of view [0090] 37,38,39,40: angular fields of view [0091] 41: optical sensor structure with color filter [0092] 42: optical sensor structure without color filter [0093] 43: metal layer in plane of optical sensor [0094] 44: metal layer in plane of aperture [0095] 45: metal layer [0096] 46: output signal [0097] : measured incidence angle [0098] : angular field of view