DE202015102980U1 - sensor - Google Patents

Abstract

Optoelectronic sensor for detecting objects (2) with at least one light transmitter (3) and at least one light receiver (4), which are arranged in such a way that light of the light emitter (3) on a transmission path (6) to a retroreflector (7) and on a receiving path (8) back to the light receiver (4) is guided, wherein the light transmitter (3) and light receiver (4) for focusing the light on a light beam according to the autocollimation principle, a common optics (9) or separate optics (9) or each associated with each other closely adjacent optics (9) according to the Doppelaugenprinzip, wherein the optoelectronic sensor (1) is adapted to the light of the light emitter (3) via a first polarizing filter (10) the transmission path (6) and the reflected light the receiving path (8) via a second polarizing filter (11) to the light receiver (4) and wherein a control and evaluation unit (12) is adapted to interrupt the light beam as Detecting detection of an object (2), characterized in that the first polarizer (10) or the second polarizer (11) on a filter support (13) at least rotatably mounted about an optical axis in an optical carrier (15), and the other second polarizing filter (11) or first polarizing filter (10) is fixed in a fixed position and the first polarizing filter (10) or the second polarizing filter can be fixed at an angle of 90 ° to the other second polarizing filter (11) or first polarizing filter (10).

Description

The present invention relates to an optoelectronic sensor for detecting objects according to the preamble of claim 1.

Photoelectric sensors are often used to monitor a surveillance area for intervention by objects. There are a variety of applications, from motion detectors and anti-theft devices to automatic door protection. Object detection also plays an important role in automation.

A reflected light barrier as an example of an object-detecting sensor consists, in simplified form, of a light emitter, such as an LED, whose emission beam strikes a retroreflector mounted at the opposite end of the surveillance area, where it is reflected back, and the reflected beam thus reflected from one in the vicinity of the Light transmitter arranged light receiver is received and is evaluated by a control and evaluation. If the light beam is interrupted, the light receiver does not receive anything and the control and evaluation unit triggers the switch-off function.

The light is passed through a beam-forming optics during transmission and reception. This can be a light barrier according to the autocollimation principle, the path or the transmission axis and the reception axis for the transmitted light and the received light being identical or lying on one axis. In this case, the optics for transmitting and receiving beam can be the same or different optics can be provided, wherein a beam splitter is provided with different optics. However, according to the dual-eye principle, the transmitter and the receiver may each be associated with a lens, with both lenses being closely adjacent and the path for transmitted light and received light being separated.

In order to distinguish whether the light from the retroreflector and not from an unwanted reflection on the light receiver, polarized light is used. After the light emitter or the light emitter, a first polarizing filter is arranged. In front of the light receiver, a second polarizing filter is arranged. The pole filters are rotated at an angle of 90 ° to each other, since the light at the retroreflector gets a rotation of the polarization by 90 °. Only the light reflected back from the retroreflector, which traverses the polarization filter of the receiver, leads to an evaluation.

The EP 1 770 413 A1 relates to a reflection light barrier with polarizing filters.

The DE 10 2006 053 229 A1 discloses an optoelectronic sensor and a method of detecting polarized light objects.

The function of the rotated by 90 ° to each other polarizer, or the crossed-oriented polarizing filter in reflection light barriers is the degree of extinction, d. H. from the alignment accuracy, namely 90 ° +/- error Xy in the optical carrier dependent.

The intended for receiving and transmitting path polarizing filters are punched in pairs in a press with a punch press stroke. The punching forms are close to each other, so that alignment errors are kept low by inhomogeneities in the polarizing filter material. The alignment error is referred to below as error X1.

Following the punching process, the polarizing filters are mounted in optical carriers or optionally in the housing. Transmitter-side polarizing filters and the receiver-side polarizing filter resulting from the same punching operation are used in the same apparatus. This ensures that errors, referred to below as errors X2, which result from the orientation of the film for press recording, do not exist. The error X2 is in 5 shown.

It still remains over a series reproduced error X3, which is due to the geometry of the punch press, namely the orientation of the dies in the press to each other, or the accuracy of the die. Is in 6 shown.

Since a complex entrainment of polarizing filters on workpiece carriers is to be avoided, in order to avoid errors X1, X2 and X3, it is necessary for the assembly steps for fastening the transmitting pole filter and receiving pole filter to take place immediately one after the other.

When fixing the polarizer films in the optics carrier, the punched-out geometry serves as a mounting reference. Often the filters are therefore arched inserted into pockets. This further restricts the extinguishing capability and the polarizing function.

Finally, in the case of a parallel light beam, the polarizing filters are no longer perpendicularly illuminated. The error resulting from the curvature of the polarizing filters is referred to below as error X4. Is in 7 shown.

The registration error resulting from the inaccuracy of the polarizer reference surfaces in the optical carrier is referred to as X5 in the following error. Is in 8th shown.

Since usually a single optical carrier is used to accommodate both differently oriented polarizer films, especially in the case of autocollimation light barriers, complex injection molding tools with a large number of slides are required.

If an optics carrier is split into a separate receiving optical carrier and a separate transmitting optical carrier, the error X6 occurs, which describes the alignment accuracy of the polarizing filter reference surfaces due to the inaccurate mounting of the individual optics carrier modules in the housing.

The disadvantage here is the occurrence of the errors X1, X2, X3, X4, X5 and X6 with corresponding disadvantages for the optical system.

Furthermore, there is a high demand on the complexity and accuracy of the injection molding tools.

Furthermore, there is a limited flexibility in the assembly process, since the polarizing filters must be processed in pairs in the same sensor.

An object of the invention is to provide an improved optoelectronic sensor. Furthermore, a better alignment accuracy of Polfiltern for optoelectronic sensors is provided to optimize the Polfilterfunktion and to increase the economic and production advantages.

The object is achieved according to claim 1 by an optoelectronic sensor for detecting objects with at least one light emitter and at least one light receiver, which are arranged to each other such that light of the light emitter is guided on a transmission path to a retroreflector and on a reception path back to the light receiver , Wherein light transmitter and light receiver for focusing the light on a light beam according to the autocollimation principle have a common optics or separate optics or each associated with each other closely adjacent optics according to the Doppelaugenprinzip, wherein the sensor is adapted to the light of the light emitter via a first polarizing filter the transmission path and the reflected light from the receiving path via a second polarizing filter to the light receiver and wherein a control and evaluation unit is adapted to detect an interruption of the light beam as detection of an object, wherein the e First polfilter or the second polarizing filter is mounted on a filter support least rotatable about an optical axis in an optics carrier, and the other second polarizer or first polarizer is fixed in place and the first polarizer or the second polarizer at an angle of 90 ° to the other second Polfilter or first polarizer is fixable.

According to the invention, it is possible to rotate the filter carrier. The aim of this rotation adjustment is to align the filter located in the filter polarizer, in terms of the desired extinction ratio optimally to the other located in the optics carrier polarizing filter. The criterion for the alignment can be, for example, the output signal of the receiver.

After alignment by rotation of the filter support is fixed. The filter carrier can be fixed or fixed in the optics carrier, for example by laser welding, ultrasonic welding, gluing, snapping, caulking or encapsulation.

The filter carrier is characterized in that it can be manufactured in different sizes or designs. Furthermore, the filter carrier can be used in various optoelectronic sensor systems.

The first or second polarizing filter is fastened, for example, by laser welding, ultrasonic welding, gluing, snapping, caulking or encapsulation in the filter carrier. This attachment is characterized by the fact that there are no high accuracy requirements for the reference surfaces for Polfilterplatzierung.

The filter carrier is placed in a receptacle on or in the optics carrier. In the optics carrier is the other second or first polarizing filter. Again, there are no high accuracy requirements for the located in the optics carrier reference surfaces for Polfilterplatzierung.

Both the optics carrier and the filter carrier are parts or assemblies in which storage or purchase from various external suppliers is possible.

According to the invention, the error X1 is reduced because the first / second polarizing filter is aligned to the second / first polarizing filter by rotation, and an alignment error can be reduced over the prior art.

The error X2 is no longer present according to the invention, since an orientation of the polarizer foil to the press receptacle no longer has an effect, since the first / second polarizing filter is aligned with the second / first polarizing filter by rotation.

Also, the error X3, which by the geometry of the punching dies in the punch press or the Accuracy of the die would occur, no longer has an effect, since the polarizer is aligned.

The error X4, which would be caused by a curvature of the polarizer, is also effectively avoided, since in the punched-out polarizer no longer the punched geometry serves as a position reference, but the polarizer without position reference in the filter support or in the slide can be fastened.

Also, the error X5, which would come about by the inaccuracy of Polfilterreferenzflächen in the filter support or in the optical carrier is effectively avoided because the punched out polarizer is no longer the punched geometry as a position reference, but the polarizer without position reference in the filter carrier or in the slide can be fastened.

Furthermore, the error X6 is avoided because the polarizing filters are aligned by rotation.

The sensor according to the invention is therefore easier to manufacture, since the polarizing filters can be provided more easily in the work preparatory steps.

The filter carrier and the optical carrier can initially be made completely isolated from each other. For example, corresponding assemblies can be obtained from different suppliers or locations. Only at the final installation of the sensor, the geometric orientation of the polarizing filter is made.

Furthermore, injection molding tools for the filter carrier or the optical carrier are less complex and thus less expensive. Furthermore, the demands on the accuracy of the injection molded parts are lower.

The individual assembly steps for the optoelectronic sensor can be automated and need not be carried out manually.

In a further embodiment, the lens is arranged on the filter carrier. As a result, the lens is firmly fixed relative to the polarizing filter. Furthermore, the lens can be positioned or adjusted through the filter carrier. Thus, the exact position of the lens during assembly of the optoelectronic sensor can be determined.

In a development of the invention, the filter carrier is displaceable in the optical carrier along the optical longitudinal axis. As a result, for example, the lens can be moved relative to the light transmitter or to the light receiver. As a result, a precisely desired distance between lens and light transmitter or light receiver can be set.

The filter carrier can be moved, for example with a gripper along the optical axis, so that the distance between the lens and the light emitter or lens and light receiver can be precisely adjusted.

In a further development of the invention, a diaphragm is arranged on the filter carrier. Through the aperture, the beam diameter of the transmission path can be set in the light transmitter. With the light receiver, the depth of field and the amount of light can be adjusted through the aperture. Due to the arrangement of the diaphragm on the filter carrier, the position of the diaphragm can be adjusted to the light emitter or to the light receiver.

In a further development of the invention, the filter carrier is tubular. In the interior of the tubular filter carrier, the components such as polarizing filter, lens and / or aperture are then attached. Due to the tubular design, the most circular components such as polarizing filter, lens and / or aperture can be easily attached. Further, by the tubular shape of the filter carrier can be easily stored rotatably in the optics carrier. However, the filter carrier can also be designed circular-cylindrical.

In a further development of the invention, the optical axes of light transmitter and light receiver are perpendicular to each other and a beam splitter is arranged at an angle of 45 ° with respect to both optical axes at the intersection of the two optical axes. The steel divider forms a coaxial system.

The invention will be explained below with regard to further advantages and features with reference to the accompanying drawings with reference to embodiments. The figures of the drawing show in:

1 an optoelectronic sensor with filter carrier and optics carrier;

2 a filter carrier in the optics carrier;

3 a sensor according to the invention according to the Doppelaugenprinzip;

4 a sensor according to the invention with a beam splitter;

5 to 8th each a mistake in the prior art.

In the following figures, identical parts are provided with identical reference numerals.

1 shows an optoelectronic sensor 1 for detecting objects with at least one light transmitter 3 and at least one light receiver 4 , which are arranged to each other such that light of the light emitter 3 on a transmit path to a retroreflector and on a receive path back to the light receiver 4 is guided, wherein light emitter 3 and light receiver 4 to focus the light according to the autocollimation principle on a light beam a common look 9 or separate optics 9 or each one another closely adjacent lens 9 assigned to the double-eye principle, wherein the sensor 1 designed for the light of the light emitter via a first polarizing filter 10 the transmission path and the reflected light from the reception path via a second polarizing filter 11 the light receiver 4 supply and wherein a control and evaluation unit 12 is designed to detect an interruption of the light beam as detection of an object, wherein the first polarizing filter 10 or the second polarizer 11 on a filter carrier 13 at least rotatable about an optical longitudinal axis 14 in an optics carrier 15 is stored, and the other second polarizing filter 11 or first polarizing filter 10 fixed in place and the first polarizer 10 or the second polarizer at an angle of 90 ° to the other second polarizer 11 or first polarizing filter 10 can be fixed.

According to the invention, it is possible to use the filter carrier 13 to turn. The aim of this rotary adjustment is that in the filter carrier 13 located polarizer 10 , in terms of the desired extinction ratio optimally to the other in the optics carrier 15 located polarizer 11 align. As a criterion for the alignment, for example, the output signal of the light receiver 4 serve.

After alignment by rotation of the filter carrier 13 fixed. The filter carrier 13 For example, it may be mounted in the optics carrier by laser welding, ultrasonic welding, gluing, snapping, caulking or overmolding.

The first polarizer 10 or the second polarizing filter 11 is for example by laser welding, ultrasonic welding, gluing, snapping, caulking or encapsulation in the filter carrier 13 attached.

The filter carrier 13 is in a recording on or in the optics carrier 15 placed. In the optics carrier 15 is the other second polarizer 11 or first polarizing filter 10 ,

The filter carrier 13 and the optics carrier 15 can be made completely isolated from each other. Only at the final installation of the sensor 1 becomes the geometric orientation of the polarizing filters 10 and 11 performed.

According to 1 is the optics on the filter carrier 9 or lens arranged. This is the look 9 or lens relative to the polarizing filter 10 firmly fixed. Next, the lens through the filter carrier 13 be positioned or adjusted. So can the exact position of the optics 9 or lens during assembly of the optoelectronic sensor 1 be determined.

According to 1 is the filter carrier 13 in the optics carrier 15 along the optical axis 14 displaceable. As a result, for example, the optics 9 or lens relative to the light emitter 3 or to the light receiver 4 be moved. This allows a precisely desired distance between optics 9 or lens and light emitter 3 or light receiver 4 be set.

The filter carrier 13 can, for example, with a gripper along the optical axis 14 be moved, so the distance between optics 9 or lens and light emitter 3 or lens and light receiver 4 can be adjusted exactly.

Next may be on the filter carrier 13 be arranged a diaphragm. Through the aperture can be at the light transmitter 3 the beam diameter of the transmission path can be adjusted. At the light receiver 4 The aperture can be used to set the depth of field and the amount of light. By the arrangement of the aperture on the filter carrier 13 can change the position of the aperture to the light transmitter 3 or to the light receiver 4 be set.

According to 1 is the filter carrier 13 tubular. Inside the tubular filter carrier 13 then the components are like polarizing filters 10 respectively. 11 , Optics 9 or lens and / or diaphragm attached. Through the tubular shape of the filter carrier 13 This can easily be in the optics carrier 15 be rotatably mounted.

2 shows the filter carrier 13 in the optics carrier 15 with the polarizer 10 and the polarizer 11 , wherein the polarizing filters are oriented at an angle of 90 ° to each other.

According to 4 stand the optical axes of light emitter 3 and light receiver 4 perpendicular to each other and a beam splitter 20 is arranged at an angle of 45 ° with respect to both optical axes at the intersection of the two optical axes. Through the steel divider 20 a coaxial system is formed.

Based on 3 is the structure of a sensor according to the invention 1 explained. The sensor 1 is preferably a reflection light barrier, which is used alone or as part of a light grid.

In a housing 18 is a light transmitter 3 provided, which may be an LED or a laser of any wavelength, inter alia, in the infrared, visible or ultraviolet range. The light source sends light through a polarizer.

The light is transmitted and passes through a beam-forming optics 9 and a viewing window 19 of the housing 18 in the actual transmission path 6 ,

The transmitted light hits the retroreflector 7 and is thrown back there with three times total reflection. So it returns as a receive beam on one with the transmit path 6 substantially coincidental - that is, apart from minimal dislocation on the order of magnitude of the microreflectors of the retroreflector 7 and unavoidable optical aberrations - receive path 8th back, re-enters the viewing window 19 in the case 18 and meets after beam shaping in the beam-forming optics 9 or lens on the light receiver 4 ,

The beam-forming optics 9 may be a simple converging lens or any other element known from optics. It can be a double lens according to the Doppelaugenprinzip with one lens for the transmission path 6 and the reception path 8th be provided. The beam-forming optics 9 can in the viewing window 19 sit or the viewing window 19 form.

The received light is passed through a second polarizing filter 11 with one to the first polarizer 10 vertical polarization direction to a light receiver 11 reflected and converted there for example by means of a photodiode or a CCD or CMOS chips in an electrical signal.

A control and evaluation unit 12 receives this electrical signal. The control and evaluation unit 12 thus recognizes if the light of the light transmitter 3 is received unhindered. If no electrical signal corresponding to a received receive beam is output, the control and evaluation unit recognizes 12 an interruption and thus an object in the beam path. The control and evaluation unit reacts to this 12 by outputting a signal for the presence of an object. This may be used for a downstream processing process in automation engineering, or alternatively be a warning or shutdown signal for an associated machine. The control and evaluation unit 12 can also with the light source 3 be connected, about to turn this on and off.

Based on 4 is the structure of another optoelectronic sensor according to the invention 1 explained. The sensor 1 is preferably a reflection light barrier, which is used alone or as part of a light grid.

In a housing 18 is a light transmitter 3 provided, which may be an LED or a laser of any wavelength, inter alia, in the infrared, visible or ultraviolet range. The light emitter sends light through a polarizing filter 10 to a beam splitter 20 , The beam splitter 20 is at an angle of 45 ° to the light emitter 3 and consists of a dielectric or a glass plate.

At the beam splitter 20 a part of the light is reflected and then has to avoid optical crosstalk in the housing 18 or absorbed in another way, not shown. The remaining part of the light is transmitted and passes through a beam-forming optics 9 and a viewing window 19 of the housing 18 in the actual transmission path 6 ,

The transmitted light hits the retroreflector 7 and is thrown back there with three times total reflection. So it returns as a receiving beam with only minor deviations on one with the transmission path 6 substantially coincidental - that is, apart from minimal dislocation on the order of magnitude of the microreflectors of the retroreflector 7 and unavoidable optical aberrations - receive path 8th back, re-enters the viewing window 19 in the case 18 and meets after beam shaping in the beam-forming optics 9 on the beam splitter 20 ,

The beam-forming optics 9 may be a simple converging lens or any other element known from optics. The beam-forming optics 9 can in the viewing window 19 sit or the viewing window 19 form.

At the beam splitter 20 a part of the reception light is transmitted and falls on the light emitter 3 , is lost for an evaluation. The remaining part of the receiving light is passed through a polarizing filter 11 with one to the polarizing filter 10 vertical polarization direction to a light receiver 4 reflected and converted there for example by means of a photodiode or a CCD or CMOS chips in an electrical signal.

A control and evaluation unit 12 receives this electrical signal as indicated 3 explained.

LIST OF REFERENCE NUMBERS

1

 Optoelectronic sensor

3

 light source

4

 light receiver

6

 transmission path

7

 retroreflector

8th

 receive path

9

 optics

10

 first polarizing filter

11

 second polarizing filter

12

 Control and evaluation unit

13

 filter support

14

 optical longitudinal axis

15

 optics carrier

16

 cover

18

 casing

19

 window

20

 beamsplitter

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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 1770413 A1 [0006]
• DE 102006053229 A1 [0007]

Claims (6)

Opto-electronic sensor for detecting objects ( 2 ) with at least one light transmitter ( 3 ) and at least one light receiver ( 4 ), which are arranged in such a way that light of the light emitter ( 3 ) to a transmission path ( 6 ) to a retroreflector ( 7 ) and on a reception path ( 8th ) back to the light receiver ( 4 ), whereby light emitters ( 3 ) and light receiver ( 4 ) to focus the light on a light beam according to the autocollimation principle a common look ( 9 ) or separate optics ( 9 ) or each have a closely adjacent to each other optics ( 9 ) is assigned to the double eye principle, wherein the optoelectronic sensor ( 1 ) is adapted to the light of the light emitter ( 3 ) via a first polarizing filter ( 10 ) the transmission path ( 6 ) and the reflected light from the reception path ( 8th ) via a second polarizing filter ( 11 ) the light receiver ( 4 ) and wherein a control and evaluation unit ( 12 ) is designed to interrupt the light beam as detection of an object ( 2 ), characterized in that the first polarizing filter ( 10 ) or the second polarizing filter ( 11 ) on a filter carrier ( 13 ) At least rotatable about an optical axis in an optics carrier ( 15 ), and the other second polarizing filter ( 11 ) or first polarizing filter ( 10 ) is fixed in place and the first polarizing filter ( 10 ) or the second polarizing filter at an angle of 90 ° to the other second polarizing filter ( 11 ) or first polarizing filter ( 10 ) is fixable. Optoelectronic sensor according to one of the preceding claims, characterized in that on the filter carrier ( 13 ) an optic ( 9 ) is arranged. Optoelectronic sensor according to claim 1, characterized in that the filter carrier ( 13 ) in the optics carrier ( 15 ) is displaceable along the optical axis. Optoelectronic sensor according to one of the preceding claims, characterized in that on the filter carrier ( 13 ) an aperture ( 16 ) is arranged. Optoelectronic sensor according to one of the preceding claims, characterized in that the filter carrier ( 13 ) is tubular. Optoelectronic sensor according to one of the preceding claims, characterized in that the optical axes of light emitter ( 3 ) and light receiver ( 4 ) are perpendicular to each other and the beam splitter ( 17 ) is arranged at an angle of 45 ° with respect to both optical axes at the intersection of the two optical axes.

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