DE102022005025A1 - OPTOELECTRONIC SENSOR - Google Patents

Abstract

The present invention relates to an optoelectronic sensor, comprising a light inlet opening and at least one light receiver for detecting received light signals and for converting the received light signals into electrical received signals, with a receiving light path extending between the light inlet opening and the at least one light receiver, which has a deflection element with a front and a rear reflection surface, wherein the deflection element is designed such that part of the received light signals are reflected on the front reflection surface and another part of the received light signals are reflected on the rear reflection surface. The front reflection surface at least partially has a filter layer which reflects or transmits received light signals depending on their wavelength and/or polarization direction. The optoelectronic sensor comprises a first and a second light receiver, wherein the light receivers and the deflection element are designed and arranged such that received light signals reflected on the front reflection surface are detected by the first light receiver and received light signals reflected on the rear reflection surface are detected by the second light receiver, wherein received light signals , which are reflected at the rear reflection surface, are transmitted twice by the front reflection surface, namely on the way to and from the rear reflection surface. The front reflection surface and the rear reflection surface are inclined to one another.

Description

The present invention relates to an optoelectronic sensor, comprising a light inlet opening and at least one light receiver for detecting received light signals and for converting the received light signals into electrical received signals, with a receiving light path extending between the light inlet opening and the at least one light receiver, which has a deflection element with a front and a rear reflection surface, wherein the deflection element is designed such that part of the received light signals are reflected on the front reflection surface and another part of the received light signals are reflected on the rear reflection surface.

Generic and generic-like optoelectronic sensors can be designed in a variety of ways and used for different purposes. Optoelectronic sensor arrangements can, for example, include a light transmitter, which emits light signals into a monitoring area, which are reflected or remitted in the direction of the optoelectronic sensor by an object that may be present in the monitoring area and are detected by the light receiver of the sensor. In some embodiments, in addition to the mere presence of an object in the surveillance area, certain properties of the object, for example its surface properties or size, can also be detected. Such arrangements are also referred to as light switches. In other sensor arrangements, a transmitted light beam is emitted in the direction of a reflector, in particular a retroreflector, and is reflected by this in the direction of the optoelectronic sensor. An interruption in the light path can be registered by the optoelectronic sensor. Such a sensor arrangement is also referred to as a light barrier. An arrangement of several light barriers is called a light curtain or light grid. Further exemplary sensor arrangements include so-called laser scanners, in which the transmitted light signals are periodically deflected in different spatial directions, for example using rotating mirrors or swiveling mirrors. This means that even larger two- or three-dimensional spatial areas can be monitored with spatial resolution.

In many optoelectronic sensor arrangements, a determination of the distance of a detected object can also be provided, for example by determining a light transit time, a phase position or also by means of triangulation.

In optoelectronic sensor arrangements, deflecting mirrors or folding mirrors are often arranged in the transmitting light path and/or in the receiving light path in order to advantageously deflect or fold the optical beam paths. In this way, in particular, the necessary installation space for the sensor arrangement can be reduced or adapted to certain complex installation situations. Furthermore, a deflection or folding of the optical beam path may also be necessary in order to include various optical elements in the beam path. A folding mirror is usually understood to mean a mirror that is integrated into the optical beam path in such a way that a deflection of usually 180° takes place, i.e. H. the beam path is reflected back into itself. Deflecting mirrors usually cause a deflection by an angle other than 180°, preferably by 90° or other angles in the range between more than 0° and less than 180°.

In EP 1 931 133 A1 a method and a device for optically detecting a structure by means of an image sensor are described, in which an optical element arranged in the imaging beam path images the structure in at least two separate and mutually offset areas of the image sensor. As a result, a structure that has a large longitudinal extent can be broken down into several successive sections and captured by the image sensor in a single recording. This decomposition can be done, for example, using a plane-parallel, double-reflecting deflection plate.

It is the object of the invention to create an optoelectronic sensor with a deflection element in the beam path, the functionality and performance of which is improved compared to conventional sensors.

The solution is achieved by an optoelectronic sensor with the features of claim 1. According to the invention it is provided that the front reflection surface at least partially has a filter layer which reflects or transmits received light signals depending on their wavelength and / or polarization direction.

In the optoelectronic sensor according to the invention, received light signals of a first wavelength and/or polarization direction can therefore be reflected on the front reflection surface, while received light signals of a second wavelength and/or polarization direction can be reflected on the rear reflection surface. The deflection element is designed in such a way that received light signals that are reflected on the rear reflection surface are reflected twice from the front whose reflection surface is let through, namely on the way to and from the rear reflection surface. By reflecting the received light signals depending on their wavelength and/or polarization direction either on the front or the rear reflection surface, the received light signals can be spatially separated from one another, which can be used, for example, to evaluate the received light signals depending on the wavelength and/or polarization direction. It is understood that the front and rear reflection surfaces are spaced apart from each other by a certain amount. Depending on the application, the term “light” here is intended to include electromagnetic radiation, in particular from the visible, ultraviolet and/or infrared wavelength range.

In addition to the elements mentioned, the optoelectronic sensor can also have further optical elements such as lenses, prisms or mirrors, which are arranged in front of and/or behind the deflection element, based on the direction of propagation of the received light signals. For example, said light entry opening can be defined by an optic or lens arranged in the receiving light path or by a diaphragm.

The filter layer, which is designed depending on the desired functionality, can be produced in a basically known manner. For example, the filter layer can be produced in the form of a single or multi-layer structure by vapor deposition or vacuum deposition of suitable substances directly on the deflection element. The filter layer can also be applied to the deflection element in the form of a film. The deflection element itself is preferably transparent for the wavelength range of the received light, which is predetermined, for example, by a light transmitting element that may be used, and can be made, for example, of glass or plastic, e.g. B. made of PMMA.

An example of an application for the optoelectronic sensor according to the invention consists in differentiating the received light signals according to their polarization direction. This can be used, for example, to make an additional distinction according to their surface properties in light sensors, which are available to detect objects that may be present in a surveillance area. While unpolarized transmitted light is at least partially polarized when reflected on a shiny object, a reflection on a matt object surface generally does not change the polarization of the reflected transmitted light.

The further configuration of the optoelectronic sensor according to the invention can be carried out in a variety of ways, in particular in accordance with the above list of generic and generic-like optoelectronic sensors, this list being purely exemplary and not exhaustive. The areas of application for generic and generic-like optoelectronic sensors are known to those skilled in the art and their structural designs are described in the relevant prior art.

According to an advantageous embodiment, the optoelectronic sensor comprises a first and a second light receiver, wherein the light receivers and the deflection element are designed and arranged such that received light signals reflected on the front reflection surface are detected by the first light receiver and received light signals reflected on the rear reflection surface are detected by the second light receiver become. This makes it possible to detect and evaluate the received light signals separated by wavelength and/or polarization direction separately from one another. The two light receivers can, for example, be arranged in a common plane, for example on a common circuit board, which reduces the manufacturing effort. A certain distance can be provided between the first and the second light receiver depending on the design of the deflection element and the geometric arrangement of the elements of the optoelectronic sensor.

According to a further advantageous embodiment, the filter layer is only provided on at least a partial area of the front reflection surface. The at least one partial region can, for example, be annular, in particular in the form of several concentric rings. Furthermore, a strip-shaped arrangement is also possible, with each strip being viewed as a partial area. Furthermore, a checkerboard pattern-like arrangement of the sub-areas is also possible. The remaining part of the front reflection surface does not have a filter layer, although another type of coating that is different from the filter layer mentioned can also be provided. By coating only one or more partial areas with the filter layer, different detection zones for the received light signals can be realized, for example a division into a near zone and a far zone.

According to a further advantageous embodiment, the front reflection surface and the rear reflection surface are flat. In this case, the convergence or divergence angle of the received light signals is not affected by the deflection element flows. With a convergent beam path, the received light signals are imaged into focal planes or focal points that are spaced apart from one another, depending on the reflection surface on which they were reflected, the distance between the focal planes depending, among other things, on the length of the optical path within the deflection element.

According to a further advantageous embodiment, the front reflection surface and the rear reflection surface are inclined to one another. This has proven to be advantageous, particularly in connection with the embodiment described above, in which the optoelectronic sensor comprises a first and a second light receiver, in order to apply the received light signals separated according to wavelength and/or polarization direction to both light receivers. Both reflection surfaces are preferably flat, but do not run parallel to one another due to the inclination. According to an alternative embodiment, however, both reflection surfaces can also run parallel to one another.

According to a further advantageous embodiment, at least one of the reflection surfaces, preferably the rear reflection surface, is curved, preferably concave. This makes it possible, in particular, to separate the focal planes in which the received light signals are imaged depending on their wavelength or polarization direction from one another to a greater extent than, for example, solely through the optical path within the deflection element, which is determined by its angular orientation and thickness. it is possible. In principle, however, the deflection element can also fulfill a beam-shaping function in addition to the deflecting and separating function, whereby the number of required optical beam-shaping elements can be reduced and, in particular, the overall length or the installation space can be reduced. Both reflection surfaces can also be curved, preferably with different radii of curvature, so that the focal lengths of the two reflection surfaces differ from one another.

According to a further advantageous embodiment, the deflection angle at which the received light signals are deflected is 90° or 180°, or at least essentially 90° or 180°. If the deflection angle is, for example, 90°, the deflection element fulfills the function of a classic deflection mirror, with the incident and exiting beam paths being at right angles to one another. If the deflection angle is 180°, this corresponds to the function of a folding mirror, in which the emerging beam path is reflected back onto the incident beam path. This is primarily used to shorten the overall length.

According to a further advantageous embodiment, the rear reflection surface has a reflective coating, for example a vapor-deposited metal layer. This allows the proportion of received light reflected on the rear reflection surface to be increased.

According to a further advantageous embodiment, the reflection properties of the filter layer can be changed in terms of their selectivity for a wavelength and/or a polarization direction in response to an electrical control signal. Such an active coating of the front reflection surface can then be influenced, for example, using an electrical voltage which is applied to the filter layer in order to adapt the optical properties of the optoelectronic sensor in a desired manner.

According to a further advantageous embodiment, the rear reflection surface can be designed in a step-shaped manner. The optical path within the deflection element therefore also depends on the point of impact of a received light signal on the deflection element. In this way, for example, additional focal levels can be created.

In a further aspect, the present invention relates to a light transmitter arrangement for emitting transmitted light into a monitoring area, comprising a light exit opening and a first light transmitter, which is set up to generate transmitted light of a first wavelength, and a second light transmitter arranged at a distance from the first light transmitter, which is used to generate of transmitted light of a second wavelength different from the first wavelength, a transmitted light path extending between the light transmitters and the light exit opening, which has a deflection element with a front and a rear reflection surface which are inclined to one another, the front reflection surface having a filter layer , which reflects or transmits transmitted light depending on its wavelength, and wherein the light transmitters and the deflection element are designed and arranged in such a way that transmitted light generated by the first light transmitter is reflected on the front reflection surface and transmitted light generated by the second light transmitter is reflected on the rear reflection surface that the transmitted light reflected on the reflection surfaces propagates along a common transmitted light axis.

Separate sections of the transmitted light path with differently extending transmitted light axes for each wavelength therefore extend between the light transmitters and the deflection element. These transmitted light paths or transmitted light axes are combined by the deflection element, so that A common section of the transmitted light path with the common transmitted light axis extends between the deflection element and the light exit opening. The light transmitter arrangement according to the invention is based on the idea that the basic idea implemented in the optoelectronic sensor according to the invention described above can also be transferred in an analogous manner to a light transmitter arrangement, with the direction of propagation of the light paths being reversed, so to speak.

The advantageous embodiments of the optoelectronic sensor according to the invention described above, in particular those which relate to the deflection element, can also be used in a corresponding and advantageous manner in the light transmitter arrangement according to the invention.

The invention also relates to an optoelectronic sensor arrangement, which comprises an optoelectronic sensor according to the invention and a light transmitter arrangement according to the invention.

The deflection element can be arranged in a stationary or adjustable, in particular rotatable, manner in relation to other components of the optoelectronic sensor or the light transmitter arrangement.

Further advantageous embodiments of the invention emerge from the subclaims, the description and the drawings.

The invention is described below using exemplary embodiments with reference to the drawings.

• 1 eine schematische Ansicht eines optoelektronischen Sensors gemäß einem ersten Ausführungsbeispiel;
• 2 eine schematische Ansicht eines optoelektronischen Sensors gemäß einem zweiten Ausführungsbeispiel;
• 3 eine schematische Ansicht eines optoelektronischen Sensors gemäß einem dritten Ausführungsbeispiel;
• 4 eine schematische Ansicht eines optoelektronischen Sensors gemäß einem vierten Ausführungsbeispiel; und
• 5 eine schematische Ansicht eines optoelektronischen Sensors gemäß einem fünften Ausführungsbeispiel.

Show it:

• 1 a schematic view of an optoelectronic sensor according to a first exemplary embodiment;
• 2 a schematic view of an optoelectronic sensor according to a second exemplary embodiment;
• 3 a schematic view of an optoelectronic sensor according to a third exemplary embodiment;
• 4 a schematic view of an optoelectronic sensor according to a fourth exemplary embodiment; and
• 5 a schematic view of an optoelectronic sensor according to a fifth exemplary embodiment.

In the following, identical or similar elements or components are referred to with the same reference numerals.

1 until 5 show optoelectronic sensors 110 to 510, which include a respective deflection element 112 to 512 in different configurations. Each deflection element 112 to 512 has a front reflection surface 14 and a rear reflection surface 16 spaced therefrom. On the front reflection surface 14, a respective filter layer 18 is applied completely or in one or more partial areas, which reflects or transmits incident light, ie received light signals and/or transmitted light signals, depending on their wavelength and/or polarization direction. The rear reflective surface 16 may have a reflective coating 20.

In 1 until 5 In a purely schematic manner, beam paths for received light 28.1, 28.2 detected by the optoelectronic sensors 110 to 510 are shown, the received light 28.1 having a first wavelength and the received light 28.2 having a second wavelength that is different from the first wavelength. In principle, the received light 28.1 can also have a first wavelength range and the received light 28.2 can have a second wavelength range, with the two wavelength ranges not overlapping. The receiving light 28.1, 28.2 enters the respective optoelectronic sensor 110 to 510 through an unspecified light entry opening. The optoelectronic sensors 110 to 510 have respective receiving optics 22 for beam shaping of the incoming received light 28.1, 28.2. Furthermore, the optoelectronic sensors 110 to 510 have either a single light receiver 24 or a first light receiver 24.1 and a second light receiver 24.2, which are set up to convert the incident received light 28.1 or 28.2 into electrical signals. In 2 the receiving optics 22 and the light receiver(s) 24, 24.1, 24.2 are not shown.

In all exemplary embodiments, the differences shown between the received light 28.1 and the received light 28.2 relate to its wavelength. The differences between the respective received light 28.1, 28.2 can alternatively or additionally also relate to its polarization direction. For example, the received light 28.1 can have a horizontal polarization and the received light 28.2 can have a vertical polarization. However, for easier understanding, reference will only be made below to possible different wavelengths or wavelength ranges.

The received light 28.1, 28.2, which may be focused by the receiving optics 22, hits the deflection element 112 to 512, with the received light 28.1 with the first wavelength being reflected on the front reflection surface 14 and the received light 28.2 with the second wavelength being reflected on the rear reflection surface 16.

With reference to the individual figures, the specific differences between the optoelectronic sensors 110 to 510 will be explained in more detail below.

In the optoelectronic sensor 110 according to 1 the deflection element 112 is designed as a plane-parallel plate. Since the received light 28.2 with the second wavelength has to pass through the deflection element 112 twice, the focal plane 30.2 of the received light 28.2 is located in front of the focal plane 30.1 of the received light 28.1 with the first wavelength, as seen in the propagation of the light. With the geometry shown, the received light 28.1 with the first wavelength is focused and the received light 28.2 with the second wavelength is detected by the light receiver 24 in a defocused manner. A differentiation of the received light 28.1, 28.2 according to the wavelength can be done, for example, by using a spatially resolving and/or color-resolving light receiver 24 and a corresponding evaluation.

In the optoelectronic sensor 210 according to 2 The deflection element 212 differs from the deflection element 112 according to 1 in that its rear reflection surface 16 is concavely curved. This gives the deflection element 212 an additional beam-shaping function with respect to the received light 28.2, so that the received light 28.2 reflected on the rear reflection surface 16 with a second wavelength is bundled in a focus point 30.2, while the received light 28.1, which was reflected on the front reflection surface 14, has its parallel Beam path maintained.

According to an exemplary embodiment, not shown, - as already mentioned above - a light transmitter arrangement in a modification of the optoelectronic sensor 210 according to 2 can be created by reversing the direction of propagation of the light paths and replacing the light receivers 24.1, 24.2 with respective light transmitters.

In the optoelectronic sensor 310 according to 3 In turn, a deflection element 312 designed as a plane-parallel plate is used, although not the entire front reflection surface 14 has a filter layer 18, but only an annular partial area 18, which, based on the sectional view in 3 as two partial areas 18 appears. As explained at the beginning, other partial areas of the front reflection surface 14 can also be provided with a filter layer 18. In this exemplary embodiment, too, the receiving light 28.1, 28.2 has different focus points 30.1, 30.2 depending on the respective reflection surface 14, 16.

The optoelectronic sensor 410 according to 4 Instead of a single light receiver, it has a first light receiver 24.1 and a second light receiver 24.2, which are arranged at a distance from one another on a common substrate 32 or a circuit board. The front reflection surface 14 and the rear reflection surface 16 of the deflection element 412 are both flat and inclined to one another, so that the deflection element 412 has a wedge-shaped shape.

The distance between the light receivers 24.1, 24.2, the angle of inclination between the reflection surfaces 14, 16 and the arrangement and orientation of the deflection element 412 in the beam path are selected so that the received light 28.1 is detected by the first light receiver 24.1 and the received light 28.2 by the second light receiver 24.2. The focus points 30.1, 30.2 are located on the respectively assigned light receiver 24.1, 24.2.

The optoelectronic sensor 510 according to 5 is designed as a (laser) scanner. In addition to the components described above, a housing 34 also contains a light transmitter 38, for example a laser, and a rotating deflecting mirror 36, which changes both the transmitted light 40 emitted by the light transmitter 38 and the received light 28.1, 28.2 at an angle of 90 ° redirected so that a flat circular monitoring area can be periodically scanned. The housing 34 is transparent to the wavelength range of the radiation used, at least in the area of light entry and exit. The annular receiving optics 22 has a central recess for receiving the light transmitter 38.

The deflection element 512 has a similar design to the deflection element 212 of 2 a concavely curved rear reflection surface 16. The light receiver 24 is arranged between the deflection element 512 and the light transmitter 38, the light transmitter 38, the receiving optics 22, the light receiver 24 and the deflection element 512 being arranged coaxially along an optical axis A. In the optoelectronic sensor 510, the focus points 30.1, 30.2 are at different distances relative to the light receiver 24, similar to the exemplary embodiments according to 1 until 3 .

Reference symbol list

110 - 510

optoelectronic sensor

112 - 512

Deflection element

14

front reflection surface

16

rear reflection surface

18

Filter layer

20

Coating

22

receiving optics

24, 24.1, 24.2

Light receiver

28.1

Receive light with first wavelength

28.2

Receiving light with second wavelength

30.1, 30.2

Focus point

32

Substrate

34

Housing

36

Deflecting mirror

38

Light transmitter

40

Transmit light

A

optical axis

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 1931133 A1 [0005]

Claims (7)

Optoelectronic sensor (110 - 510), comprising a light inlet opening and at least one light receiver (24, 24.1, 24.2) for detecting received light signals and for converting the received light signals into electrical received signals, with between the light inlet opening and the at least one light receiver (24, 24.1, 24.2) a receiving light path extends, which has a deflection element (112 - 512) with a front and a rear reflection surface (14, 16), the deflection element (112 - 512) being designed such that part of the received signals on the front reflection surface ( 14) and another part of the received signals are reflected on the rear reflection surface (16), characterized in that the front reflection surface (14) at least partially has a filter layer (18) which reflects received light signals depending on their wavelength and / or polarization direction or allows the optoelectronic sensor (110 - 510) to comprise a first and a second light receiver (24.1, 24.2), the light receivers (24.1, 24.2) and the deflection element (112 - 512) being designed and arranged in such a way that on the front Received light signals reflected on the reflection surface (14) are detected by the first light receiver (24.1) and received light signals reflected on the rear reflection surface (16) are detected by the second light receiver (24.2), wherein received light signals that are reflected on the rear reflection surface are transmitted twice by the front reflection surface on the way to and from the rear reflection surface, and that the front reflection surface (14) and the rear reflection surface (16) are inclined to one another. Photoelectric sensor (110 - 510) according to Claim 1 , characterized in that the filter layer (18) is provided only on at least a partial area of the front reflection surface (14). Photoelectronic sensor (110 - 510) according to one of the preceding claims, characterized in that the front reflection surface (14) and the rear reflection surface (16) are planar. Photoelectric sensor (110 - 510) according to Claim 1 or 2 , characterized in that at least one of the reflection surfaces (14, 16), preferably the rear reflection surface (16), is curved, preferably concave. Optoelectronic sensor (110 - 510) according to one of the preceding claims, characterized in that the deflection angle at which the received light signals are deflected is 90° or 180°. Photoelectronic sensor (110 - 510) according to one of the preceding claims, characterized in that the rear reflection surface (16) has a reflective coating (20). Optoelectronic sensor (110 - 510) according to one of the preceding claims, characterized in that the reflection properties of the filter layer (18) can be changed with regard to their selectivity for a wavelength and/or a polarization direction in response to an electrical control signal.

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