DE202015100482U1 - triangulation - Google Patents

Abstract

Triangulation light scanner with a light transmitter (12) for emitting transmitted light (16) into a detection zone, an array of receiving elements (26) having light receiver (24) for receiving light (34) from the detection zone, which of an object to be detected (18 ), wherein the receiving elements (26) generate respective received signals, a receiving optical system (20) arranged in the beam path between the detection zone and the light receiver (24), which comprises a plurality of imaging elements (22A, 22B) for generating individual spaced-apart light spots (36A, 36B). from the remitted light (34) on the light receiver (24), wherein the imaging elements (22A, 22B) are arranged in an array extending at least in a triangulation direction (T), and wherein the positions of the individual light spots (36A, 36B) on the light receiver (24) in the triangulation direction (T) depending on the distance of the object (18) and an evaluation unit (38) for generating a detection signal from the received signals on the basis of the positions of the individual light spots (36A, 36B) on the light receiver (24), characterized in that a respective imaging element (22A, 22B) has a plurality of adjacent receiving elements (22A, 22B). 26), each detection area (28A, 28B) being subdivided into at least a first subarea (30A, 30B) and a second subarea (32A, 32B), and a respective boundary between the first Partial area (30A, 30B) and the second partial area (32A, 32B) corresponds to the position of an individual light spot (36A, 36B) generated by the associated imaging element (22A, 22B) for an object (18) which is at a predetermined reference distance from the object Triangulation light scanner (10) is located, and that the evaluation unit (38) is adapted to the detection signal based on a difference between the zusa Generated received signals of the first partial areas (30A, 30B) associated with receiving elements (26) and the combined received signals of the second partial areas (32A, 32B) associated with receiving elements (26) to generate.

Description

The invention relates to a triangulation light scanner with a light transmitter for emitting transmitted light in a detection zone, an array of receiving elements having light receiver for receiving light from the detection zone, which is remitted from an object to be detected, wherein the receiving elements generate respective received signals, one in the beam path Receiving optics arranged between the detection zone and the light receiver, which has a plurality of imaging elements for generating respective spaced apart individual light spots from the remitted light on the light receiver, wherein the imaging elements are arranged in an at least in a triangulation direction extending array, and wherein the positions of the individual light spots on the Receive light receiver in the Triangulationsrichtung depending on the distance of the object, and an evaluation unit for generating a detection signal from the received signals n based on the positions of the individual light spots on the light receiver.

It is known to determine the presence and / or distance of objects in a surveillance area with light sensors that work according to the triangulation principle. Such a triangulation light scanner comprises a light transmitter, for example a light-emitting diode or a laser, and optionally a transmitting optics, in order to emit a transmitted light beam into a detection zone to an object to be detected which may be located there. The transmitted light can be remitted from such an object, d. H. diffused or specularly reflected, and be detected by a light receiver, which forms a receiving unit together with a receiving optics. The light receiver consists in known solutions of at least one row of photosensitive receiving elements.

Depending on the distance between the triangulation light sensor and the remitting object, the position of a light spot generated by the remitted light on the light receiver changes in the so-called triangulation direction. There is a clear geometric relationship between the point of impact on the light receiver and the distance of the detected object. By evaluating the light distribution on the light receiver, the distance between the object and the light sensor can thus be determined. Furthermore, it can be determined on appropriate evaluation of the light distribution on the light receiver, whether an object is within or outside a Tastbereich, d. H. whether the distance of the object is within or outside a predetermined limit, also referred to as scanning distance.

In order to achieve in particular a high accuracy in determining the distance, such a light receiver must have a plurality of photosensitive receiving elements which are arranged side by side in the triangulation direction.

In triangulated triangulation light scanners, the light receiver comprises at least two receiving elements, a so-called near element being struck by a light beam when reflected by an object located within a near range in front of the triangulation light key, and a so-called remote element in such a manner is arranged to be hit by a light beam which is reflected by an object located in a distant area in front of the triangulation light sensor. By definition, the far-end region is further away from the triangulation probe than the near-end region. For signal evaluation, a difference between the photodiode currents of the receiving elements of these two areas is formed.

In order to ensure the greatest possible detection reliability, both a high sensitivity, in order to safely detect even weakly remitting objects, as well as a high spatial resolution is sought. Furthermore, it is desirable to minimize the size of the Triangulationslichttasters for space-critical applications.

The efficiency of the light sensor is in particular by the average distance, d. H. determines the distance between the receiving optics and the light receiver, the diameter of the light spot or spots on the light receiver and the diameter of the imaging element (s) of the receiving optics, these three variables being related. Thus, in general, with decreasing focal length, the imaging element diameter must also decrease in order to ensure the smallest possible spot diameter on the light receiver, which in turn adversely affects the received amount of light energy and thus the sensitivity. If one accepts a larger light spot diameter to direct more energy to the light receiver, the spatial resolution and thus the quality of the background suppression decreases.

It is known to use a receiving optics having a plurality of imaging elements, which are arranged in a row extending in the triangulation direction to increase the photosensitivity without affecting the spatial resolution. The imaging elements generate respective individual light spots on the light receiver, wherein their positions on the light receiver, for example by means of pattern recognition can be evaluated. Such a solution is in DE 10 2007 004 632 A1 described.

For carrying out such a pattern recognition, however, a relatively complex evaluation unit is required since complex arithmetic operations have to be carried out for this purpose.

It is the object of the invention to provide a triangulation light scanner, which enables a simple and cost-effective evaluation of the received signals for generating the detection signal with high sensitivity and good spatial resolution.

The solution is provided by a triangulation light scanner having the features of claim 1. The invention provides that a respective imaging element is associated with a plurality of adjacent detection elements comprehensive detection area, each detection area is divided at least in a first and a second sub-area, with a respective boundary between the first and second sub-areas corresponds to a position of an individual light spot generated by the associated imaging element for an object which is at a predetermined reference distance from the triangulation light switch, and in that the evaluation unit is adapted to detect the detection signal based on a difference between the combined received signals The reception elements assigned to the first partial areas and the combined reception signals of the reception elements assigned to the second partial areas are to be generated.

If an object is within the detection zone, transmitted light reflected from this object hits the light receiver within the respective detection areas. If the object is located in the reference distance, also referred to as scanning distance, from the triangulation light sensor, the respective location of incidence of an individual light spot on the light receiver defines the boundary between the first and the second subarea of this detection area.

A respective boundary between the first subregion and the second subregion largely corresponds to the position of an individual light spot generated by the associated imaging element for an object which is at a predetermined reference distance from the triangulation probe. At the switching point, the light spot position corresponds exactly to the boundary between the subregions.

If the distance of the object is smaller or larger than the reference distance, the individual light spots at least predominantly fall into the first partial areas or at least predominantly into the second partial areas. Thus, the first subregions of the detection regions correspond to a respective near region of the detection zone and the second subregions of the detection regions correspond to a respective far region of the detection zone or vice versa, depending on the definition.

The respective detection areas and thus also their subareas are coherent in their own right. However, it is possible for one or more receiving elements to be present between two adjacent detection areas, which are not assigned to a detection area and can remain unused for the generation of the detection signal. The reference distance for all boundaries between the respective subregions is the same. The size of the detection areas and / or the partial areas may vary.

An array of receiving elements or imaging elements is understood to mean arrangements which are one-dimensional, that is to say one-dimensional. H. may be line-shaped, or even two-dimensional, wherein the number of elements in the triangulation direction is generally substantially greater than in the transverse direction.

In the present text, the term "detection zone" is used for a zone in which an object to be detected can stay or stop, wherein the detection zone may include a near and a far area. The term "detection area" designates a region of the receiving element which comprises a plurality of receiving elements and is subdivided into subregions.

The invention is not limited only to detection areas with two partial areas, but may basically also comprise three or more partial areas.

The triangulation light scanner according to the invention makes it possible to electronically bundle the light energy which is present in the plurality of individual light spots produced by the imaging elements so that the detected energy increases and thus also the signal-to-noise ratio increases, without making it costly Evaluation circuit is required.

According to an advantageous embodiment, the evaluation unit is adapted to determine a sum signal from the received signals of the receiving elements, wherein the received signals of the first sub-areas associated receiving elements with a first factor and the received signals of the second sub-areas associated receiving elements with a second factor, which differs from the first factor, at least with respect to its sign, weighted. Furthermore, the evaluation unit is designed to generate the detection signal on the basis of the sum signal.

In the simplest case, both factors have the value 1, so that, for example, the received signals of the receiving elements associated with the first partial regions are weighted positively and the received signals of the receiving elements associated with the second partial regions are weighted negatively. In this example, an object whose distance is exactly equal to the reference distance or range results in a sum signal of zero magnitude. If the individual light spots completely or at least for the most part meet the first partial areas, then the sum signal is positive, but if they hit the second partial areas completely or for the most part, the sum signal is negative. By an appropriate evaluation of the sum signal can thus be determined in particular whether the detected object is in a near range, in a long range or just at the distance of the range.

As an alternative to the embodiment described above, it may be provided that the evaluation unit is designed to determine a first sum signal from the received signals of the receiving elements associated with the first partial regions and a second composite signal from the received signals of the receiving elements associated with the second partial regions and the detection signal on the basis to produce a difference of the sum signals. Thus, there is no inversion of individual received signals, as is the case in the previously explained embodiment, but first the received signals for both subregions are added up separately, in order then to form the difference.

In principle, both sum signals can be equally weighted, but it is also possible to weight at least one of the sum signals with a factor.

According to an advantageous embodiment, the evaluation unit has at least one adder, which is designed to determine the sum signal or signals from the received signals. Such adding devices are suitable for a simple and inexpensive determination of the sum signal or signals. Depending on which of the above-mentioned variants of the sum signal formation is selected, one or two adders are provided.

According to a further advantageous embodiment of the invention, the evaluation unit is adapted to an association of the receiving elements to a respective detection area and / or to a respective sub-area by means of a teach-in operation, in which an object is arranged in the desired reference distance, and / or on the basis of a Assignment table or assignment function depending on the reference distance. This makes it possible to use the triangulation light scanner for different detection ranges, since the assignment of the reception elements to the detection areas or partial areas is variable. Preferably, both the assignment of the receiving elements to a particular imaging element, d. H. the definition of the detection areas, as well as the definition of the boundaries between the first and second sub-areas variable.

When assigning the receiving elements, the various methods can be combined as desired. Thus, for example, the assignment to the detection areas can be made via an allocation table or assignment function, while the boundaries, i. H. the assignment to a respective sub-area, by means of a teach-in process takes place.

For example, it is also possible that the assignment to a respective detection area is fixed and only the assignment to one of the sub-areas is performed according to one of the methods mentioned.

Finally, both the assignment to the detection areas as well as to the sub-areas can be fixed, whereby the evaluation unit can be designed particularly simple.

According to a further advantageous embodiment, it is provided that the imaging elements are designed such that the diameter of the individual light spots generated by them on the light receiver is smaller in the triangulation direction than in the direction orthogonal thereto. For this purpose, for. As lenses with non-round aperture, but also astigmatic lenses or toric lenses are used. As a result, a better light output without deterioration of the spatial resolution in the triangulation direction can be achieved.

Further advantageous embodiments are specified in the subclaims, the description and the drawing.

The invention will now be described by way of example with reference to the drawings. In this show:

1 a schematic representation of a Triangulationslichttasters invention according to an embodiment,

2 a detailed representation of the triangulation light of 1 , and

3 further schematic representations of the triangulation light of 1 and 2 including associated signal curves for objects at different distances to the triangulation light sensor in combined representation.

1 shows the schematic beam path of a triangulation light sensor according to the invention 10 ,

From a light transmitter 12 , For example, a laser diode, transmission light is 16 sent out in the direction of a detection zone. A transmission optics 14 forms the transmission light 16 if necessary to a parallel beam. The transmitted light 16 meets an object 18 in the detection zone and becomes of this object 18 to the triangulation light scanner 10 remitted. The remitted light 34 meets a receiving optics 20 , which has several lenticular imaging elements 22A . 22B includes, which are arranged side by side in the triangulation direction T.

The picture elements 22A . 22B bundle the remitted light 34 in respective individual light spots 36A . 36B that of a light receiver 24 be detected and converted into electrical received signals. The receiver configured as a light receiver 24 has a plurality of receiving elements 26 ( 2 ), which are also arranged side by side in the triangulation direction T.

Every picture element 22A . 22B is a respective detection area 28A . 28B of the light receiver 24 associated with each detection area 28A . 28B several receiving elements 26 includes ( 2 ).

The of the receiving elements 26 generated received signals are sent to an evaluation unit 38 which is based on the positions of the individual light spots 36A . 36B on the light receiver 24 generates a detection signal.

In the described embodiment, the receiving optics 20 for the sake of simplicity, there are only two imaging elements 22A . 22B on. Accordingly, on the light receiver 24 also only two detection areas 28A . 28B Are defined. In fact, the number of imaging elements and, accordingly, the number of detection areas can be substantially greater, for example 5, 10 or 20. The light receiver 24 can instead of in 2 illustrated thirteen receiving elements 26 also have a much higher number of receiving elements. For example, the light receiver 128 Have arranged in a row receiving elements.

Each detection area 28A . 28B is in each case in a first subarea 30A respectively. 30B and a second subarea 32A respectively. 32B divided. The boundary G between the subareas 30A and 32A respectively. 30B and 32B is chosen so that the individual light spots 36A . 36B to the respective boundary between the first subarea 30A . 30B and the second subarea 32A . 32B meets when the distance of the remitting object 18 from the triangulation light scanner 10 exactly corresponds to a given scanning distance TW or reference distance (see 3 center).

When the distance of the object 18 from the triangulation light scanner 10 is smaller than the range TW, the object 18 So in a so-called short-range, meet the individual light spots 36A . 36B at least predominantly within the respective first subareas 30A . 30B on the light receiver 24 (please refer 3 below).

If, however, the distance of the object 18 from the triangulation light scanner 10 greater than the range TW is the object 18 So in a so-called distant area, meet the individual light spots 36A . 36B at least predominantly within the respective second subareas 32A . 32B on the light receiver 24 (please refer 3 above).

As in 1 to 3 can be seen, are located between the detection areas 28A . 28B as well as in the selected representation above the detection range 28B and below the detection area 28A Areas of the light receiver 24 , no detection area 28A . 28B are assigned and therefore not taken into account in the calculation of the sum signal.

Both the detection areas 28A . 28B as well as the first and second sections 30A . 30B . 32A . 32B can depend on their position on the light receiver 24 geometriebingtingt have different sizes, since individual light spots 36A . 36B the farther from the one through the transmitted light 16 are removed defined axis, with the same change in the object distance experienced a larger change in position.

The assignment of the receiving elements 26 to the respective detection areas 28A . 28B and the respective subareas 30A . 30B . 32A . 32B can z. B. by means of a teach-in process. Defining the detection areas 28A . 28B For example, the object may be at a maximum and a minimum distance from the triangulation light sensor 10 be positioned and the respective impact positions of the individual light spots on the light receiver, which represent the boundaries of the detection areas are evaluated. The assignment to the respective subareas 30A . 30B . 32A . 32B can be done by the object is positioned in the desired scanning distance TW, in which case the place of incidence of the individual light spots 36A . 36B on the light receiver 24 the respective boundaries between the first subareas 30A . 30B and the second subareas 32A . 32B Are defined.

Alternatively, the assignment to the detection areas 28A . 28B and / or the subareas 30A . 30B . 32A . 32B with the aid of an assignment table and / or an assignment function, wherein the assignment table and / or the assignment function can be created experimentally and / or on the basis of geometric calculations.

In 1 to 3 includes the evaluation unit 38 an adding device 40 which has several inputs E and one output A ( 2 and 3 ). Every reception element 26 is connected to an input E of the adder 40 connected, between the respective receiving element and the adding device is a linking unit (not shown), which in dependence on the assignment of the receiving elements 26 to the detection areas 28A . 28B and the subareas 30A . 30B . 32A . 32B can weight or interrupt the received signals by a factor. For clarity, is in 1 to 3 for every section 30A . 30B . 32A . 32B only one connection line shown.

While at the in the adding device 40 successive addition to determine the sum signal, the received signals of the first partial areas 30A . 30B are weighted by a factor of +1, the received signals of the second subareas 32A . 32B weighted by a factor of -1. Inputs E of the evaluation unit 38 are marked accordingly with the mentioned factors. For explanation it is pointed out that in the illustration in 1 In addition, the connections of the first sections 30A . 30B or the second subareas 32A . 32B are summarized.

In the right part of 3 is that of the individual light spots 36A . 36B generated light distribution on a detection area of the light receiver 24 plotted in the triangulation direction T for the different object distances, wherein the boundary G between the first partial areas 30A . 30B and the second subareas 32A . 32B corresponding to the position of a light spot reflected from an object in the range TW is marked.

The above-described calculation of the received signals taking into account the weighting factors causes the signal component which is located to the left of the marking TW to be subtracted from the signal component which is located to the right of the marking TW.

When the object 18 located in the far range ( 3 above), the signal component to the left of the marker TW predominates and leads to a negative signal at the output A of the adder 40 ,

Is the object located? 18 in the range TW ( 3 Middle), the signal components on both sides of the marking TW are the same size, so that a zero-sized signal is output at the output A.

If, on the other hand, the object 18 located within the vicinity ( 3 below), the signal component to the right of the marker TW predominates, so that a positive sum signal is output at the output A.

Thus, the sum signal provides information about the distance of the object 18 to the triangulation light scanner 10 , on the basis of which the evaluation unit 38 can generate a detection signal.

The described 3 is to be understood as follows: The distance of the object from the triangulation button is in the representation of 3 above larger than in 3 below. In the area a) the 3 are each the object 18 and the triangulation button 10 shown in their mutual position to each other. In area b) the 3 is in each case the light receiver 24 shown with the evaluation. In addition, in area b) the 3 indicated schematically by dots where on the receiver the light spots 36A . 36B incident. The signal curves are finally in the range c) the 3 recognizable.

LIST OF REFERENCE NUMBERS

10

triangulation

12

light source

14

transmission optics

16

transmitted light

18

object

20

receiving optics

22A, 22B

imaging element

24

light receiver

26

receiving element

28A, 28B

detection range

30A, 30B

first subarea

32A, 32B

second subarea

34

remitted light

36A, 36B

Single light spot

38

evaluation

40

adder

e

entrance

A

output

G

Border between two subregions of a detection area

T

Triangulationsrichtung

TW

Operating distance

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

• DE 102007004632 A1 [0008]

Claims (8)

Triangulation light scanner with a light transmitter ( 12 ) for transmitting transmitted light ( 16 ) into a detection zone, an array of receiving elements ( 26 ) having light receiver ( 24 ) for receiving light ( 34 ) from the detection zone, which of an object to be detected ( 18 ), wherein the receiving elements ( 26 ) generate respective received signals, one in the beam path between detection zone and light receiver ( 24 ) arranged receiving optics ( 20 ), which several imaging elements ( 22A . 22B ) for generating respective spaced individual light spots ( 36A . 36B ) from the remitted light ( 34 ) on the light receiver ( 24 ), wherein the imaging elements ( 22A . 22B ) are arranged in an array extending at least in a triangulation direction (T), and wherein the positions of the individual light spots ( 36A . 36B ) on the light receiver ( 24 ) in the triangulation direction (T) as a function of the distance of the object ( 18 ), and an evaluation unit ( 38 ) for generating a detection signal from the reception signals on the basis of the positions of the individual light spots (FIG. 36A . 36B ) on the light receiver ( 24 ), characterized in that a respective imaging element ( 22A . 22B ) a plurality of adjacent receiving elements ( 26 ) comprehensive detection area ( 28A . 28B ), each detection area ( 28A . 28B ) at least into a first subarea ( 30A . 30B ) and a second subregion ( 32A . 32B ), and wherein a respective boundary between the first subregion ( 30A . 30B ) and the second subarea ( 32A . 32B ) the position of one of the associated imaging element ( 22A . 22B ) produced individual light spot ( 36A . 36B ) for an object ( 18 ), which is at a predetermined reference distance from the triangulation light sensor ( 10 ), and that the evaluation unit ( 38 ) is adapted to determine the detection signal on the basis of a difference between the combined received signals of the first subregions ( 30A . 30B ) associated with receiving elements ( 26 ) and the combined received signals of the second subregions ( 32A . 32B ) associated with receiving elements ( 26 ) to create. Triangulation light scanner according to claim 1, characterized in that the evaluation unit ( 38 ) is adapted to generate a sum signal from the received signals of the receiving elements ( 26 ), wherein the received signals of the first partial areas ( 30A . 30B ) associated with receiving elements ( 26 ) with a first factor and the received signals of the second subregions ( 32A . 32B ) associated with receiving elements ( 26 ) are weighted with a second factor that differs from the first factor, at least with respect to its sign, and that the evaluation unit ( 38 ) is adapted to generate the detection signal based on the sum signal. Triangulation light scanner according to claim 1, characterized in that the evaluation unit ( 38 ) is adapted to generate a first sum signal from the received signals of the first subregions ( 30A . 30B ) associated with receiving elements ( 26 ) and a second sum signal from the received signals of the second subregions ( 32A . 32B ) associated with receiving elements ( 26 ) and to generate the detection signal based on a difference of these sum signals. Triangulation light scanner according to claim 3, characterized in that the evaluation unit ( 38 ) is designed to weight at least one of the sum signals by a factor. Triangulation light scanner according to one of claims 2 to 4, characterized in that the evaluation unit ( 38 ) at least one adding device ( 40 ), which is designed to determine the or the sum signals from the received signals. Triangulation light scanner according to claim 5, characterized in that the evaluation unit ( 38 ) is adapted to receive the receiving elements ( 26 ) according to their assignment to the subareas ( 30A . 30B . 32A . 32B ) with the at least one adding device ( 40 ) interconnect. Triangulation light scanner according to one of the preceding claims, characterized in that the evaluation unit ( 38 ) is adapted to an assignment of the receiving elements ( 26 ) to a respective detection area ( 28A . 28B ) and / or to a respective subarea ( 30A . 30B . 32A . 32B ) by means of a learning process in which an object ( 18 ) at the desired reference distance, and / or based on an allocation table or assignment function depending on the reference distance. Triangulation light scanner according to one of the preceding claims, characterized in that the imaging elements ( 22A . 22B ) are designed such that the diameter of them on the light receiver ( 24 ) produced individual light spots ( 36A . 36B ) is smaller in the triangulation direction (T) than in the direction orthogonal thereto.

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