Sensor and method for determining the transparency of a window of the sensor

Abstract

The present invention is a sensor (10) comprising a housing (40) and a scanning unit (60). The scanning unit includes a rotating mirror (12) that deflects scanning light (SE, SR) for emission and reception. The housing (40) includes windows (42a, 42b). The sensor (10) comprises a window monitoring unit (50). The window monitoring unit (50) comprises at least a first optoelectronic component (18.1…18.22) and a second optoelectronic component (16). The optoelectronic components (18.1, …, 18.22 and 16) and the optical components are arranged so as to be able to generate a plurality of test light paths (T.X), because the optical components are optical waveguides (20). The optical waveguide (20) is attached to the rotating mirror (12) and can rotate together with the rotating mirror (12), and the test light paths (T.X) at different angular positions end at at least one same second optoelectronic component (16).

Description

Technical Field

[0001] The present invention relates to the sensor described in the preamble of claim 1.

Background Art

[0002] General-purpose sensors are used to identify objects within a scanning field. Such sensors include a housing for an operating unit through which scanning light is transmitted through a window of the sensor. Such sensors are particularly affected by environmental influences such as snow, rain, and dirt in outdoor applications. Due to these environmental influences, the transparency or translucency of the sensor window may be affected, and there may be cases where the scanning light does not exit the sensor or the reflected light does not enter the sensor.

[0003] To address this problem, sensors with a configuration for testing the transparency of the sensor window are already known.

Prior Art Documents

Patent Documents

[0004] German Patent Application Publication No. 10 2015 105 264 A1 discloses an optoelectronic sensor with a test light scanner, which includes a test light deflector that rotates together with the deflection means of the scanning unit. The test light emitter and the test light receiver are arranged around the housing.

[0005] Therefore, the test light receiver and the test light emitter are arranged adjacent to each other in the radiation direction. The emitted light passes through the window and is reflected by the test light deflector attached to the rotating deflection means. With this configuration, the path through the window can be analyzed. The intensity of the received beam is used to determine the dirt on the window.

[0006] European Patent Application Publication No. 2 237 065 A1 discloses a test light device for checking the window of a sensor. The measurement radiation is deflected by a rotating mirror. The receiver and the LED of the test light device are in a fixed position relative to the mirror and are arranged on the same side of the mirror. The test light emitted from the LED is reflected by a mirror fixed to the housing, and this mirror is arranged on the opposite side of the test light emitter and the test light receiver. This arrangement enables continuous measurement along the periphery of the window.

[0007] This arrangement has the drawback that electrical components are arranged on the rotating part, i.e., on the mirror, while the circuit board is usually attached to the fixed part of the housing. Depending on the size of the rotating mirror, the diode attached to the mirror may affect the balance of the rotating mirror element.

Summary of the Invention

Problems to be Solved by the Invention

[0008] An object of the present invention is to provide an improved window monitoring system. This object is solved by the combination of the features of claim 1 and the features of its preamble. The dependent claims are further advantageous embodiments of the present invention.

Means for Solving the Problems

[0009] In a known method, a general sensor includes a housing and a scanning unit arranged within the housing for scanning an angular detection range by emitting and receiving scanning light. The scanning unit includes a rotating mirror for deflecting the emitted scanning light and / or the received scanning light. Due to the rotation of the rotating mirror, the scanning light preferably scans the angular detection range in a plurality of planes. For example, the scanning unit can include a LiDAR system, in which the scanning light is preferably pulsed and the distance is determined by evaluating the flight time of the pulse and its reflection, which is generally known as TOF evaluation.

[0010] The housing includes a window through which the scanning light can pass. The window extends circumferentially over the angular detection range and extends in a direction parallel to the rotation axis of the rotary mirror. At least one window element can be inclined with respect to the rotation axis. The window in the present invention is a part of a transparent housing through which the scanning light can pass. The transparency of the window is also displayed for the test light.

[0011] Furthermore, the sensor also includes a window monitoring unit that determines the transparency of the window. The window monitoring unit includes a first optoelectronic component and a second optoelectronic component, and can generate a test light path between them by sending test light from the first optoelectronic component to the second optoelectronic component or vice versa.

[0012] At least one test light path is generated such that the test light passes through the window. A part of the test light path passing through the window is oblique, preferably substantially perpendicular, to the path of the scanning light.

[0013] At least one first optoelectronic component and at least one second optoelectronic component are attached to the housing.

[0014] Furthermore, the window monitoring unit includes an optical component that deflects the test light between the first optoelectronic component and the second optoelectronic component. Furthermore, the window monitoring unit includes an evaluation unit configured to evaluate the change in the power of the received test light to determine whether there is a significant amount of dirt or the like on the window and its transparency has significantly decreased.

[0015] The optical component, at least one first optoelectronic component, and at least one second optoelectronic component are arranged such that a plurality of test light paths are established along the angular detection range of the scanning unit.

Advantages of the Invention

[0016] According to the present invention, the optical component is an optical guide that guides the test light to a part of its test light path. The optical guide is attached to the rotating mirror so as to rotate together with the rotating mirror, and can guide different test light paths at different angular positions of the window to the same second optoelectronic component. Therefore, a plurality of test light paths end at a common end point and have a fixed position in particular.

[0017] According to this configuration, by simply attaching the optical guide to the rotating mirror, the resolution of the angular positions of the plurality of test light paths can be made very high, because the resolution depends on the size of the optical guide rather than the size of the optoelectronic component.

[0018] The optical guide is preferably a small plastic piece that has little or negligible effect on the balance of the mirror with respect to the rotation characteristics of the mirror. Further, there is no need to facilitate the power supply of the optoelectronic component and various signal transfers between the rotating electrical component and the circuit board attached to the housing. The optical guide uses the effect of total internal reflection (TIR) to guide light from a first end having a first coupling structure for coupling light from the first optoelectronic component to a second end having a second coupling structure for coupling light from the second optoelectronic component.

[0019] Light from at least one optoelectronic component is introduced into the optical guide within a correct angular range, captured within the optical guide, mainly stays within the optical guide, and is either extracted by an extraction function or, when it encounters the surface at an angle less than the critical angle, is guided to at least one optoelectronic component for reception.

[0020] In a further embodiment, the optical guide is preferably made of plastic, particularly polycarbonate. The plastic usually has a refractive index of about 1.5.

[0021] According to a preferred embodiment, the window monitoring unit includes a plurality of the first optoelectronic components and one of the second optoelectronic components to establish a plurality of test light paths.

[0022] With this arrangement, each of the plurality of first optoelectronic components can establish a plurality of the test optical paths with the second optoelectronic component according to the angular position of the optical guide.

[0023] When the first optoelectronic component is an emitter, they can operate in pulse mode, and each pulse of the same emitter can establish different test optical paths according to different angular positions of the optical guide during the pulse.

[0024] According to a further improvement of the present invention, the second coupling structure of the optical guide is located at the rotation center of the rotary mirror, and combines or separates light of different optical paths to the second optoelectronic component. With this arrangement, the angular positions during the full rotation of the mirror can be covered by a single second optoelectronic component.

[0025] Preferably, the second optoelectronic component is arranged to coincide with the rotation center of the rotary mirror and faces the second coupling structure of the optical guide. According to this arrangement, the test light can be directly guided to the second optoelectronic component.

[0026] According to another solution, the window monitoring unit may include an additional optical guide for guiding light from the rotation center to the second optoelectronic component. In this arrangement, the first coupling structure of the additional optical guide is arranged to coincide with the rotation axis of the rotary mirror. According to this embodiment, both the first optoelectronic component and the second optoelectronic component can be mounted on the same circuit board.

[0027] When the second optoelectronic component is a receiver, the test light coupled to the optical guide is separated at the rotation center of the rotary mirror and irradiates this receiver. Therefore, the test light separated from the optical guide illuminates the receiver, and during the rotation of the mirror, the test light may be continuously received over the entire angular detection range.

[0028] In a highly preferred embodiment, the optical guide is an optical fiber or prism extending radially from the center of rotation. The optical fiber, channel or prism is very lightweight and has little impact on the balance of the mirror. Further, since the optical fiber, channel or prism has a defined size (cross-section), its coupling structure can be an inclined surface directed towards the first optoelectronic component, and the position of the test light path can be easily determined according to the angular position of the rotating mirror.

[0029] When the optical guide is a prism, the coupling structure can be established by the inclined surface.

[0030] In a further preferred embodiment, the second optoelectronic component is a receiver, particularly a photodiode. Usually, the receiver occupies a larger space than the LED emitter, so the spatial resolution can be improved. The emitter and the receiver preferably emit and receive infrared rays.

[0031] According to an advantageous embodiment, the window monitoring unit includes a plurality of the first optoelectronic components which are emitters, particularly LEDs, distributed along the contour of the window over the angular detection range.

[0032] In a more preferred embodiment, the window monitoring unit includes a shield surrounding the plurality of the first optoelectronic components, and the shield includes conical cavities around each of the plurality of the first optoelectronic components. This gives a clear shape to the emitted light, making the established test light path very clear, and in particular realizing a clear opening angle of the conical test light beam.

[0033] According to a further embodiment of the present invention, there is at least one lens between at least one of the first optoelectronic components and the optical guide, and the lens is configured as a converging lens having a focus on the side of the first optoelectronic component.

[0034] As a result, in at least one cross-sectional plane containing the rotation axis, the boundary of the light beam between the lens and the optical guide becomes very acute.

[0035] As a result, it becomes possible to transmit the test light substantially in parallel through the window element.

[0036] Preferably, the lens has a convex-curved cross-section in at least one cross-sectional plane containing the rotation axis. More preferably, the lens has a curved shape, particularly a circular or arc shape, when viewed in a plane perpendicular to the rotation axis, and extends over at least a part of the angle detection range (α). As a result, each lens has a plurality of focal points distributed along the circumference of a sector or a circle.

[0037] The window monitoring unit can include a circular mirror at the same height as the optical guide. The circular mirror deflects the test light from the first optoelectronic component to the optical guide or vice versa. According to this embodiment, the optical guide does not need to have a first coupling structure directed towards the first optoelectronic component along the direction of light, and can be arranged laterally, particularly perpendicularly, with respect to the first optoelectronic component. As a result of adopting the circular mirror, the optical guide can have an extension that is the same as or smaller than the radius of the mirror. This improves the balance of the rotating mirror as compared with an optical guide that extends beyond the circumference of the rotating mirror.

[0038] Furthermore, the circular mirror can increase the amount of energy that can be transmitted through the test light path when the angular positions of the first coupling structure of the optical guide and the first optoelectronic component during operation are different. In the context of the present invention, an optoelectronic component is in operation during measurement in the case of a receiver and during emission in the case of an emitter.

[0039] The circular mirror increases the number of test optical paths with sufficient strength. This is because the number of test optical paths is not limited to the test optical paths where the first and second optoelectronic components are in the same angular range, but also includes additional test optical paths including angular offsets. Thereby, the resolution of the window monitoring unit can be effectively improved without requiring additional optoelectronic components.

[0040] According to a further embodiment of the present invention, the window includes two window elements, which are arranged one above the other and inclined towards each other when viewed along the direction of the rotation axis. Preferably, the two window elements are optically separated, and the radiated scanning light passes through one of the window elements, and the reflected scanning light passes through the other window element.

[0041] The window monitoring unit is configured such that the test optical path passes through both window elements.

[0042] The window monitoring unit is preferably configured to acquire test light along the test optical path, and at least a first test optical path among the test optical paths is defined to have a first offset between the angular position of the optical guide and the first optoelectronic component in operation, and at least a second test optical path is defined to have a second offset between the angular position of the optical guide and another first optoelectronic component in operation, and the second offset is different from the first offset in a defined lateral offset distance and / or lateral offset direction. According to this evaluation, the vertical resolution can be improved, particularly when the optical paths are generated in a mesh shape.

[0043] More preferably, the lateral offset distance is 1 / 8 or more, particularly 1 / 4 or more of the extension of the height of the window, thereby enabling sufficient inclination to specify the vertical position of the spot on the window.

[0044] According to a further advantageous embodiment, the window monitoring unit is designed to acquire the intensity of the intersecting optical paths. The intersecting test optical paths include that the position of the first active optoelectronic component of the second optical path has an offset in the first offset direction with respect to the first active optoelectronic component of the first test optical path, and that the first angular position of the optical waveguide of the first test optical path and the second angular position of the optical waveguide of the second test optical path have an offset in a second offset direction opposite to the first offset direction, and are generated when this is the case.

[0045] The mesh of the test optical paths established in this way can improve the determination of the position and size of the spots that stain the window. By improving the determination of the spots on the window, the operation of the scanning unit can be controlled in a more differentiated manner.

[0046] The invention further relates to a method for determining the transparency of a window of a sensor comprising a first window element, a second window element and an evaluation unit, as described above. The angular position of the optical waveguide and the activation of the first optoelectronic component and / or the second optoelectronic component are synchronized such that an optical mesh of test optical paths is established. The optical mesh is evaluated based on the measured intensities associated with the test optical paths. The change in the transparency of the window is determined on the first window element and / or the second window element.

[0047] The optical mesh within the scope of the invention can in particular be established by successively generating one specific optical path at a time.

[0048] Further advantages, features and potential uses of the invention can be understood from the following description in conjunction with the embodiments shown in the drawings.

[0049] Throughout the description, the claims and the drawings, these terms and the associated reference signs are used as described in the attached list of reference signs.

Brief Description of the Drawings

[0050]

Figure 1

Figure 2

Figure 3a

Figure 3b

Figure 4

Embodiments for Carrying Out the Invention

[0051] FIG. 1 shows a schematic cross-sectional view I-I of an embodiment of a sensor 10 according to the present invention. The sensor 10 includes an upper cover 44, a lower cover 46, and a housing 40 having a window with a first window element 42a and a second window element 42b inclined with respect to each other. The sensor 10 includes a scanning unit 60, which includes scanning light emitters 14a, 15a, scanning light receivers 14b, 15b, and a rotating mirror 12, and scans the environment over a predetermined angular detection range. As can be seen from the schematic cross-sectional view along II-II of FIG. 2, the angular detection range in this embodiment is about 270°.

[0052] Referring to FIG. 1, the sensor 10 includes a window monitoring unit 50 including a plurality of first optoelectronic components 18.1 to 18.22 embodied as infrared LEDs. The first optoelectronic components 18.1 to 18.22 are each surrounded by a shield 28, which includes a conical cavity 32 that functions as a beam shaping cavity and gives a defined opening angle in a defined shape of the light emitted by the first optoelectronic component 18.X, particularly in a conical test light beam.

[0053] Furthermore, the window monitoring unit 50 includes a second optoelectronic component 16 configured as a photodiode. The second optoelectronic component 16 is arranged to coincide with the rotation axis R of the rotary mirror 12 and is fixed to the housing 40. Since the second optoelectronic component 16 does not move during the operation of the sensor 10, it can be easily electrically connected as measured by a sensor electronic device (not shown).

[0054] As shown in FIG. 2, the first optoelectronic components 18.1 to 18.22 are arranged around the window elements 42a and 42b along the angle detection range α. The first optoelectronic components 18.1 to 18.22 emit light beams passing through the first window element 42a and the second window element 42b to generate a test light path T.X.

[0055] According to the present invention, the window monitoring unit 50 includes an optical guide 20, which is attached to the rotary mirror 12 so as to be movable together with the rotary mirror 12, particularly rotatable. The optical guide 20 of the present embodiment is a plastic prism having a first coupling structure 22a and a second coupling structure 22b. The optical guide 20 is configured such that the first coupling structure 22a extends in the radial direction of the rotary mirror 12. This means that light hitting the optical guide 20 in a direction generally perpendicular to the rotation axis R is taken into the optical guide 20 and directed toward the second coupling structure 22b. The optical guide 20 is configured such that the second coupling structure 22b separates light in a direction parallel to the rotation axis R.

[0056] According to this embodiment, the second optoelectronic component 16 is attached to coincide with the rotation axis R, and the light separated from the optical guide 20 by the second coupling structure 22b is directly guided to the second optoelectronic component 16.

[0057] According to this arrangement, the optical guide 20 can receive test light at any angular position according to the current rotation angle of the rotary mirror 12.

[0058] The first optoelectronic component 18.X is arranged such that the test light moves generally parallel to the rotation axis R.

[0059] Furthermore, the window monitoring unit 50 includes a circular mirror 30 that deflects the test light radially for reception by the optical waveguide 20. The circular mirror 30 generally deflects the test light from the axial direction to the radial direction. Further, due to its circularity, the circular mirror 30 focuses the test light having a path oblique to the rotation axis R rather than parallel to the rotation axis R. This utilizes the phenomenon that the test light is radiated in a conical shape rather than as a circular beam.

[0060] FIG. 1 shows that the test light radiated from the first optoelectronic component 18.4 travels along the path T.1. In this situation, the test light is radiated from the first optoelectronic component 18.4, passes through the second window element 42b, and then passes through the first window element 42a. After passing through the first window element 42a and the second window element 42b, the test light is deflected from the axial direction to the radial direction by the circular mirror 30.

[0061] In the situation shown in FIG. 1, the rotating mirror 12 is in a position where the optical waveguide 20 is at the same angular position as the first optoelectronic component 18.4. The test light that has been generally redirected in the radial direction hits the first coupling structure 22a generally perpendicularly. The test light is taken into the optical waveguide 20 and guided along the optical waveguide 20 to the second coupling structure 22b at the center of rotation of the rotating mirror 12. There, the test light is extracted from the optical waveguide 20 and directly guided to the second optoelectronic component 16, which is a photodiode arranged in a straight line with the center of rotation of the rotating mirror 12. The second optoelectronic component 16 is arranged on the rotating mirror 12, and the light-sensitive surface of the second optoelectronic component 16 faces the rotating mirror.

[0062] Figure 1 also shows test light path T.5 that is received by the optical guide 20 and then by the second optoelectronic component 16 when the rotating mirror is rotated by 180°. Further, as shown in Figure 1, the sensor 10 may optionally comprise a convex lens 36, which is preferably ring-shaped when viewed from above and extends over a sector covering all of the first optoelectronic component 18.X. This lens 36 is a converging lens that has a focus at a position close to the side surface of the first optoelectronic component. Thus, this lens has a convex curved surface as can be seen in the cross-sectional view. Thereby, for example, it becomes possible to reduce the angle of the test light beam radiated from the lens and passing through the inclined first window element 42a and second window element 42b. Thereby, it becomes possible to well cover the entire depth of the inclined first window element 42a and second window element 42b.

[0063] Figure 2 shows a schematic cross-sectional view of the sensor along II-II. The rotating mirror 12 has a circular upper surface, and the facets (mirror surfaces) of the rotating mirror 12 are arranged in a triangular cross-section.

[0064] An embodiment of the rotating mirror 12 enables an angular scanning range α of approximately 270°. The optical guide 20 extends from the center of rotation to the circumference of the rotating mirror 12. The optical guide 20 does not extend beyond the body of the rotating mirror 12. This arrangement has a good effect on the balance of the rotating mirror 12.

[0065] The position of the second optoelectronic component 16 is indicated by a dashed-line square along the rotation axis R. The test light radiated from the first optoelectronic component 18.X can be received at various angular positions that can be received by the first coupling structure 22a.

[0066] It is clear that the number of analyzable optical paths corresponds to at least the number of the first optoelectronic components 18. Since the optical guide 20 can pass through all the first optoelectronic components 18 when the rotating mirror 12 makes one rotation, it is clear that the number of analyzable optical paths corresponds to at least the number of the first optoelectronic components 18.X. For each angular position of the optical guide 20 that coincides with the position of the first optoelectronic component, a test optical path can be established. This is illustratively shown by the further angular position at which the optical guide 20 is directed towards the first optoelectronic components 18.19.

[0067] A further advantageous effect of the sensor 10 according to the invention is that additional test optical paths T.X can be generated by enabling an angular offset position between the first coupling structure 22a and the first optoelectronic component 18.X. This means that a test optical path is generated by the irradiation of the first optoelectronic component 18.X when the first coupling structure 22a has an angular offset with respect to the first optoelectronic component. The generated test optical path is oblique. According to this option, it is possible to create a mesh of test optical paths only by synchronizing the activation of the first optoelectronic component with the angular position of the rotating mirror 12.

[0068] Thereby, the number of test optical paths can be increased without being limited by the space situation. As explained with reference to FIG. 1, the circular mirror 30 improves the energy level that can be detected in such an offset situation. Furthermore, the beam shaping cavity 32 enables a very spatially well-defined test optical path and contributes in particular to the improved evaluation of the test optical paths generated by the offset arrangement. FIG. 2 shows in a top view a ring-shaped lens 36 that extends over a 270° sector covering all of the first optoelectronic components 18.X.

[0069] The ring-shaped lens 36 has the effect of narrowing the spread of the cone of the test optical beam TB in the cross-sectional plane including the axis of rotation and does not have such an influence in the circumferential direction. FIG. 3a shows in a schematic side view a further embodiment of the sensor 110 according to the invention.

[0070] The sensor 110 includes a housing 140 that includes an upper cover 144, a lower cover 146, and a window with a first window element 142a and a second window element 142b. The first window element 142a and the second window element 142b are inclined with respect to each other. The sensor 110 includes a scanning unit 160, which includes a rotary mirror 112, a scanning light emitter 114a, and a scanning light receiver 114b, and scans the environment over a predetermined angle detection range.

[0071] The sensor 110 according to the present invention includes a window monitoring unit 150 that includes a plurality of first optoelectronic components 118.1, 118.2, 118.3, 118.4, 118.5 configured as infrared LEDs.

[0072] Furthermore, the window monitoring unit 150 includes a second optoelectronic component 116 configured as a photodiode. The second optoelectronic component 116 is disposed on the same circuit board 148 as the first optoelectronic components 118.X. Accordingly, the first optoelectronic components 118.X and the second optoelectronic component 116 are attached at fixed positions in the housing 140. Since neither the second optoelectronic component 116 nor the first optoelectronic components 118.X move during the operation of the sensor 110, they can be easily electrically connected as measured by a sensor electronic device (not shown).

[0073] Similar to the description in FIG. 2, the first optoelectronic components 118.X are arranged around the window 142b along the angle detection range α.

[0074] As an example, the first optoelectronic component 118.1 emits a light beam that passes through the second window 142b and the first window 142a along the test optical path T.10.

[0075] According to the present invention, the window monitoring unit 160 includes an optical guide 120, which is attached to the rotary mirror 112 so as to be movable / rotatable together with the rotary mirror 112. The optical guide 120 of this embodiment is a plastic prism having a first coupling structure 122a and a second coupling structure 122b. The optical guide 120 is configured such that the first coupling structure 122a is positioned in a direction parallel to the rotation axis R of the rotary mirror 112. This means that light hitting the optical guide 220 in a direction generally parallel to the rotation axis R is coupled into the optical guide 120 and directed toward the second coupling structure 122b. The test light can be radiated from the first optoelectronic component 118.X generally parallel to the rotation axis R and directly received by the optical guide 120.

[0076] The optical guide 120 is configured such that the second coupling end 122 separates light in a direction parallel to the rotation axis R.

[0077] As a further difference from the embodiment of FIG. 1, the second optoelectronic component 116 is not attached so as to coincide with the rotation axis R. According to this embodiment, the window monitoring unit 160 includes an additional optical guide 124 arranged such that the first coupling structure 126a coincides with the rotation axis R, whereby the test light separated from the optical guide 120 at the second coupling structure 122b is guided to the first coupling structure 126a of the additional optical guide 124.

[0078] Next, the test light passes through the second optical guide 124 and is guided to the second coupling structure 126b, where the test light is separated from the optical guide 124 and irradiates the second optoelectronic component 116.

[0079] Similar to the arrangement of FIG. 1, the optical guide 120 can receive test light at all angular positions according to the current rotation angle of the rotary mirror 112. In contrast to the optical guide 20 of the arrangement of FIG. 1, this optical guide 120 has a structure like a lens at the first coupling structure 122a. Thereby, the reception characteristics of the oblique test light path are improved without using an additional mirror. When there is an angular offset between the angular position of the operating first optoelectronic component 118.X and the position of the second coupling structure 122a of the optical guide 120, an oblique test light path is generated.

[0080] FIG. 3a illustrates how the test light emitted from the first optoelectronic component 118.1 travels along the path T.10. The test light emitted from the first optoelectronic component 118.1 passes through the second window element 142b and then through the first window element 142a. After passing through the first window element 142a and the second window element 142b, the test light hits the first coupling structure 122a. The light is captured into the optical guide 120 and guided along the optical guide 120 to the second coupling structure 122b at the center of rotation of the rotary mirror 112. Then, the test light is extracted from the optical guide 120 and coupled to another optical guide 124. Next, the test light is received by the second optoelectronic component 116 which is a photodiode. By using the additional optical guide 124, the second optoelectronic component 116 can be arranged more freely within the housing 144.

[0081] FIG. 3b shows the embodiment of FIG. 3a, where the rotary mirror 112 is at a different angular position, i.e., a position shifted by 90°, and the optical guide 120 extends in the corresponding radial direction.

[0082] FIG. 3b shows that three test light paths T.13, T.14, T15 can be generated at a single angular position of the optical guide 120. One test light path T.14 is generated by the first optoelectronic component 118.4 when the first optoelectronic component 118.4 is directly below the first coupling structure 122a of the optical guide 120. The test light paths T.13, T.15 are generated by the first optoelectronic components 118.3, 118.5 when the optical guide 120 is above the first optoelectronic component 118.4. Thus, the test light paths T.13, T.14 passing obliquely through the window elements 142a, 142b are generated.

[0083] For better understanding, a further position of the optical guide 120' shown by a dashed line is shown in FIG. 3b. At this angular position, the test light paths T12', T13', T14' can be generated.

[0084] According to this example, it is clear that the resolution of the optical path passing through the window element can be increased, and an easy and reliable connection of the optoelectronic components can be maintained.

[0085] FIG. 4 is a schematic diagram of a sensor 200 specifically showing a related part of a window monitoring system having a rotation axis. For clarity, the scanning part of the sensor is not shown. However, the rotation axis R is the rotation axis of a mirror (not shown) of the scanning device, and this mirror is driven by a motor 260. The window monitoring unit includes a second optoelectronic component 216 that is a receiver, an optical guide 220 that rotates about the rotation axis R, and a plurality of first optoelectronic components 218.1, 218.2, 218.3, 218.4, 218.5, 218.5, …, 218.10 (also referred to as 218.X). The first optoelectronic component 218.X is configured as an emitter, that is, an LED.

[0086] The window monitoring unit is preferably implemented to acquire test light along a test optical path T.X. Among the test optical paths T.X, at least the first test optical path T.25 is defined to have a first offset between the angular position LP1 of the optical guide 220 and the operating first optoelectronic component 218.5, and at least the second test optical path T.21 is defined to have a second offset between the angular position LP4 of the optical guide and another operating first optoelectronic component 218.1. The second offset is different from the first offset in the defined lateral offset distance and / or lateral offset direction. In particular, intersecting test optical paths T.21, T.25 are generated.

[0087] The intersecting test optical paths are generated in the following case, that is, when the position of the first optoelectronic component 218.1 during the operation of the second test optical path T.21 includes an offset in the first offset direction with respect to the first optoelectronic component 218.5 during the operation of the first test optical path 25, and the first angular position LP.1 of the optical guide 220 of the first test optical path T.25 and the second angular position LP.4 of the optical guide of the second test optical path T.21 include a second offset, and the second offset direction is opposite to the first offset direction. With this setting, cross information is obtained, so the so-called shadowing effect can be avoided.

[0088] To obtain information through the optical mesh, the evaluation unit 250 activates a first optoelectronic component, which is an LED in this example, to emit pulsed test light, establishes a test optical path through the optical guide 220 at the current angular position LP.X, and then it is received by a single receiver 216.

[0089] The current angular position LP.X is recognized by the evaluation unit 250 as the angular position of a mirror (not shown). As a result, the position of the optical guide 220 attached to the mirror rotating about the rotation axis R can be easily derived, particularly from the motor 260, more specifically its controller. Depending on the angular position LP.X and the position of the first optoelectronic component 218.X during emission, a specific test optical path T.X can be generated. By synchronizing the activation of the first optoelectronic component with the angular position of the optical guide 220, the window monitoring unit 210 is designed to obtain the intensities of a plurality of optical paths, particularly including a plurality of intersecting optical paths (e.g., T.21, T.25).

[0090] By evaluating such a plurality of test optical paths T.X, an optical mesh of the test optical path T.X is generated. Since the size of the optical guide is relatively small, this optical mesh can achieve a much clearer angular position LP.X than using an individual receiver for each position and can have a very high resolution.

[0091] According to the present invention, detailed information based on an optical mesh with a very dense mesh can be obtained. Therefore, based on the obtained detailed information, a more accurate evaluation of the position and size of spots contaminating the window can be performed. By sequentially generating test light paths, preferably one by one, an optical mesh is generated, and the evaluation unit evaluates the transparency of the window after all test light paths belonging to the optical mesh have been measured.

[0092] By improving the determination of changes in the transparency of the window, the operation of the scanning unit can be controlled in a more differentiated manner, and specific actions can be selected according to the window element where the spot has occurred. Therefore, for example, it is possible to avoid unnecessarily shutting down the sensor.

Explanation of Reference Numerals

[0093] 10: Sensor 12: Rotating mirror 14a: Scanning light emitter 14b: Scanning light receiver 15a: Scanning light emitter 15b: Scanning light receiver 16: Second optoelectronic component 18: First optoelectronic component 20: Optical guide 22a: First coupling structure 22b: Second coupling structure 26: Window monitoring unit 28: Shield 30: Circular mirror 32: Conical cavity 36: Lens 40: Housing 42a: First window element 42b: Second window element 44: Upper cover 46: Lower cover 50: Window monitoring unit 60: Scanning unit 110: Sensor 112: Rotating mirror 114a: Scanning light emitter 114b: Scanning light receiver 116: Second optoelectronic component 118.X: First optoelectronic component 120: Optical guide 122a: First coupling structure 122b: Second coupling structure 124: Additional optical guide 126a: First coupling structure 126b: Second coupling structure 140: Housing 142a: First window element 142b: Second window element 144: Upper cover 146: Lower cover 148: Circuit board 150: Window monitoring unit 160: Scanning unit 200: Sensor 210: Window monitoring unit 216: Second optoelectronic component 218.X: First optoelectronic component 220: Optical guide 250: Evaluation unit 260: Motor α: Angle detection range R: Rotation axis SE: Emitted scanning light SR: Received scanning light T.X: Test light path TB: Test light beam LP.X: Angular position of the optical guide

Claims

1. Sensor (10), The system comprises a housing (40) and a scanning unit (60) disposed within the housing (40) that scans an angle detection range (α) by emitting and receiving scanning light (SE, SR). The scanning unit (60) includes a rotating mirror (12) for deflecting scanning light (SE, SR) for emission and reception. The housing (40) extends over the angle detection range (α) and includes windows (42a, 42b) through which the scanning light (SE, SR) can pass. Furthermore, the sensor (10) includes a window monitoring unit (50) that detects dirt on the windows (42a, 42b), The window monitoring unit (50) comprises at least first optoelectronic components (18.1...18.22) and second optoelectronic components (16), and a test light path (T.1, T.2, T.3...) is established between them by sending test light from the first optoelectronic component (18.X) to the second optoelectronic component (16) or vice versa. The aforementioned test light path (T.X) passes through the windows (42a, 42b), Furthermore, the window monitoring unit (50) includes an optical component that can change the direction of the test light. The first optoelectronic component (18.1, ..., 18.22) and the second optoelectronic component (16) are mounted in the housing (40), The optoelectronic components (18.1, ..., 18.22 and 16) and the optical components are arranged to generate a plurality of test light paths (T.X) along the angle detection range (α) of the scanning unit (60), since the optical components are optical guides (20) that guide the test light between at least one first optoelectronic component (18.1, ..., 18.22) and at least one second optoelectronic component (16). The optical guide (20) is attached to the rotating mirror (12) and can rotate together with the rotating mirror (12). A sensor in which the test light paths (T.X) at different angular positions terminate at at least one identical second optoelectronic component (16).

2. A sensor according to claim 1, The window monitoring unit (50) is characterized by comprising a plurality of first optoelectronic components (18.1, ..., 18.22) and a single second optoelectronic component (16) for establishing a plurality of test optical paths (T.X).

3. A sensor according to claim 1 or 2, The sensor is characterized in that the optical guide (20) has a second coupling structure (22b) at the rotation center of the rotating mirror (12) and couples or separates light from different optical paths to the second optoelectronic component (16).

4. A sensor according to claim 1 or 2, The sensor is characterized in that the optical guide (20) is an optical fiber, a prism, or a channel.

5. The sensor according to claim 4, A sensor characterized in that the optical guide (20) is the prism, and its coupling structure is established by an inclined surface.

6. The sensor according to claim 3, A sensor characterized in that the second optoelectronic component (16) is arranged to coincide with the rotation axis (R) of the rotating mirror (12).

7. The sensor according to claim 3, The sensor is characterized in that the window monitoring unit (150) comprises an additional optical guide (124) for directing light to the second optoelectronic component (116), and the first coupling structure (126a) is positioned to coincide with the rotation axis (R) of the rotating mirror (112).

8. A sensor according to claim 1 or 2, A sensor characterized in that the second optoelectronic component (16) is an optical receiver, particularly a photodiode.

9. The sensor according to claim 6, A sensor characterized in that there are a plurality of first photoelectronic components (18.X), which are emitters, i.e., LEDs, distributed over the angle detection range parallel to the contour of the windows (42a, 42b).

10. A sensor according to claim 1 or 2, The window monitoring unit (50) is equipped with a circular mirror (30) at approximately the height of the optical guide (20), The sensor is characterized in that the circular mirror (30) deflects the test light between the first optoelectronic component (16) and the optical guide (20).

11. The sensor according to claim 9, The window monitoring unit (50) includes a shield (28) surrounding a plurality of the first optoelectronic components (18.1, ..., 18.22), The sensor is characterized in that the shield (28) comprises a conical cavity (32) around each of the plurality of first optoelectronic components (18.1, ..., 18.22).

12. A sensor according to claim 1 or 2, The window comprises two window elements (42a, 42b) that are inclined relative to each other. The sensor is characterized in that the two window elements (42a, 42b) are positioned on top of each other in an axial view of the rotation axis (R) of the rotating mirror (12).

13. The sensor according to claim 12, A sensor characterized in that the two window elements (42a, 42b) are optically separated, thereby reducing crosstalk between emitted scanning light (SE) and received scanning light (SR).

14. The sensor according to claim 12, The window monitoring unit (50) is configured such that the test light passes through both of the window elements (42a, 42b), and the sensor is characterized in that

15. A sensor according to claim 1 or 2, There is at least one lens between at least one of the first optoelectronic components (18.X, 118.X, 218.X) and the optical guide (20, 120, 220), The sensor is characterized in that the lens (36) is configured as a converging lens whose focal point is close to the first photoelectronic component (18.X, 118.X, 218.X).

16. The sensor according to claim 15, The sensor is characterized in that the lens (36) has a circular ring shape or a circular sector shape in the circumferential direction and extends over at least a portion of the angle detection range (α).

17. A sensor according to claim 1 or 2, The evaluation unit (250) is configured to acquire the test light along the test light path (T.X), Of these, at least the first optical path (T14, T21) is defined to have a first offset between the angular position of the optical guide (20, 120, 220) and the operating first optoelectronic component (18.X, 118.X, 218.X), At least the second optical path (T14', T25) is defined to have a second angular offset between the angular position (LP.X) of the optical guide and the operating first optoelectronic component (18.X, 118.X, 218.X), The sensor is characterized in that the second offset differs from the first offset in a defined angular offset distance and / or angular offset direction.

18. The sensor according to claim 17, The sensor is characterized in that the evaluation unit (250) is designed to acquire the intensity of multiple intersecting optical paths (T.13, T.14'; T.21, T.25) and evaluate the optical mesh formed by the optical paths.

19. A method for determining the transparency of a sensor window according to claim 1 or 2, The sensor (10, 200) comprises a window having first window elements (42a, 242a) and second window elements (42b, 242b), and an evaluation unit (250). The angular position of the optical guides (20, 220) and the activation of the first optoelectronic components (18.x, 118.X, 218.X) and / or the second optoelectronic components (16, 116, 216) are synchronized so that an optical mesh is established by the test optical path. The optical mesh is evaluated based on the measured intensity associated with the test optical path (T.X). A method in which the change in the transparency of the window is determined by the first window element (42a, 242a) and / or the second window element (42b, 242b).

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