EP0967583B1 - Opto-electronic sensor device - Google Patents

Description

The invention relates to an optoelectronic sensor device for monitoring a protection area, at least with one transmission element, one Receiving element and a reflection unit with at least one first and a second reflection element, one of the transmission element emitted along the protected area to the first reflection element Send light bundle using the first reflection element as a deflecting light beam to the second reflection element and by means of of the second reflection element as a reception light bundle along the Protection area can be deflected to the receiving element.

Such sensor devices are, for example, at the edge of a security area arranged a machine tool, if necessary To enter this security area to be detected by factory personnel and trigger a warning signal or a shutdown signal. Here serves the Reflection unit for deflecting the transmitted light beam first around an offset distance and finally towards the receiving element, so that from the transmit light beam and from the receive light beam simultaneously different sections of the protected area are monitored can. In particular for deflecting the transmitted light beam by 180 ° and by a certain offset distance between the transmit and receive light beams are mechanical from individual optical elements composite triple reflection units known (see e.g. DE-A-19 533 044), for example have a flat mirror as a first reflection element and as second reflection element one of the plane mirror by the offset distance spaced roof edge element, which consists of two in There are planar mirrors arranged at an angle of 90 ° to one another.

A disadvantage of the known optoelectronic sensor devices The type described is that in particular with a large offset distance the adjustment of their reflection units for exact redirection of the transmitted light beam on the receiving element difficult and often can only be accomplished by trained specialist personnel. Especially in the case of the triple reflection units mentioned, their production has been proven expensive because their reflection elements at certain angles to each other must be arranged precisely. A subsequent change in Location of these reflection elements, for example to change the offset distance, is not possible without complex adjustment measures.

It is an object of the invention to provide an optoelectronic sensor device of the type mentioned to create that with little effort to produce and with an adjustable offset distance to the required Redirection of the transmitted light beam to the receiving element on simple Way to adjust.

This object is achieved in that at least one of the reflection elements of the reflection unit as an expansion reflector trained to deflect and expand the light beam in question is.

The reflection elements are used in the sensor device according to the invention So not only to redirect the light beam in question, but at least one of the reflection elements causes in addition to the deflection an expansion of the light beam.

This widening of a light beam advantageously enlarges it Angle availability. This makes the adjustment of the expansion reflector trained reflection element simplified because its Angular alignment to redirect the light beam to the next one Reflection or reception element due to the expansion of the deflected Beams can not be set with the same accuracy must be like a light beam with a comparatively small beam diameter.

The reverse is the arrangement and adjustment of the following Elements easier because a subsequent element is not exactly on the Longitudinal axis of the light beam acting on this element is arranged must be, but also due to the expansion of this light beam this can be arranged slightly adjacent to one for the monitoring function of the sensor device sufficient amount of light to recieve. It can also expand the light beam - With its further deflection at a subsequent next reflection element - In a corresponding way, the adjustment of this Simplify the sense of the next element.

The adjustment can thus be carried out comparatively quickly, and it can also be done by unskilled personnel, especially by the operator of the sensor device, for example after this to change the course of the transmit and receive light beams has been converted. In addition, the invention Sensor device flexible in different environmental conditions can be used because the light beam is deflected by means of the reflection unit for example, effects of temperature expansion or vibrations large machine tools, on which or adjacent to which the reflection unit is attached, not or only slightly disturbed becomes.

In a similar manner as above for the adjustment of the invention Sensor device explained, their manufacture is also simplified in an advantageous manner. Because of the training according to the invention the requirements for the accuracy of the position and the angular orientation the reflection elements are comparatively small, can be very simple adjustment mechanisms are provided, or it can be based on these are completely dispensed with. For example, it is possible to use the reflection elements in a housing of the reflection unit by a simple Snap or snap into place. In addition to the simplified Manufacturing also results in an advantageously small size the reflection unit, which new arrangement options for the Allows reflection unit.

Compared to the use of a transmission light bundle that has been expanded from the outset the sensor device according to the invention has the advantage that the light beam only at the for the adjustment of the sensor device critical sections of the beam path takes place, which means that with a Widening of the light bundle accompanied by a reduction in its light intensity can be kept comparatively low.

Because of this effect of reducing the light intensity of the expanded The light beam of the invention works particularly well for comparative purposes short distances of each widened light beam.

The expansion reflector of the sensor device according to the invention is preferably designed as a curved expansion mirror, in particular as essentially convex expansion mirror. Also essentially one concave curvature of the expansion mirror is possible. On Such an expansion mirror can be produced in a simple manner, for example by injection molding or deep drawing and subsequent vapor deposition with a reflective layer.

A widening mirror suitable for the sensor device according to the invention causes the expansion of one reflected on its curved surface Light beam, depending on the radius of curvature the curvature of the mirror surface acted upon by the light beam. The radius of curvature of the curvature can be spherical, i.e. in cross section be provided as a radius of a circle, toric or aspherical. It is possible to use different radii of curvature strong widening of a light beam at different, with respect provide reflection elements arranged one behind the other in the beam path.

The expansion of the light beam through the. Expansion reflector can either along essentially a single direction perpendicular to the longitudinal axis of the light beam deflected by the expansion reflector take place, or along essentially two each to said Longitudinal axis and directions perpendicular to each other. For the former The expansion reflector can be used to expand the light beam as a convex expansion mirror with the shape of a part the lateral surface of a cylinder.

An expansion of the light beam along its entire circumference can be easily achieved if the expansion reflector as Expansion mirror essentially in the form of part of the surface a ball is formed. A widening mirror can be used in a corresponding manner the shape of part of the lateral surface of a torid or Own barrel body, that is, a body that results from the rotation of one curved line, for example a circular line or a parabola. Furthermore, the expansion mirror can take the form of part of the Have surface of a body that is similar to a sphere or Barrel body is formed, but with consistently or at least partially aspherical radii of curvature. If the expansion mirror is not is formed purely spherical, the expansion of a reflected Light beam in different directions perpendicular to the longitudinal axis of the reflected light beam to different degrees, according to the each assigned radius of curvature of the surface of the expansion mirror.

As an alternative to designing the expansion reflector as a curved one Expansion mirrors can be used to achieve any other optical elements the effect of a redirection and a simultaneous expansion of the Light beam can be used. In particular, it is possible to use the expansion reflector as a combination of a flat mirror and a diverging lens train.

In a preferred embodiment of the sensor device according to the invention the reflection unit has exactly two reflection elements, and the transmitting element and the receiving element on the one hand or the reflection unit on the other hand are essentially opposite to each other Sides of the protection area arranged so that the transmit light beam and the received light beam in opposite to each other Beam directions run between these two sides. In particular the two light beams can be parallel and spaced apart by an offset distance run towards each other, so the reflection unit ultimately causes a U-shaped deflection of the transmitted light beam by 180 °. The However, transmit and receive light bundles can also have any angle take each other and / or cut each other.

While it is particularly accurate with the embodiment of the invention two reflection elements is preferred if all reflection elements the reflection unit is designed as a curved expansion mirror it is also possible to use some of the reflection elements in a conventional manner to train, for example as a flat mirror or as a roof edge element.

In the context of the invention, the reflection unit can also do more than that have two preferred reflection elements. In this case the Deflection of the transmitted light beam by means of the two reflection elements mentioned to the receiving element at least indirectly, namely about the additional reflection element or elements. In particular can be the third between the first and the second reflection element Reflection element can be provided a semi-transparent mirror, the one Part of the light beam that impacts him for additional enforcement of the protection area with a light beam in the direction of an additional one Redirects reception elements.

Furthermore, it is possible within the scope of the invention that the transmitting element and the receiving element on opposite sides of the Protection area are arranged while the reflection unit essentially is located in the center of the protected area and the redirection of the transmitted light beam by an offset distance, but essentially without changing direction, so that the light beam, for example follows a step-like course.

The invention also extends to at least two reflection elements having reflection unit, which in a similar manner as described above for the sensor unit according to the invention for deflection of a transmitted light bundle on the reflection elements to one Receiving element is provided, and in the at least one of the reflection elements is designed as an expansion reflector, in addition to Deflection causes an expansion of the light beam in question. This Reflection unit can be constructed essentially as in the above Described in connection with the sensor device according to the invention. In particular, it is preferred if the expansion reflector as convex expansion mirror is formed.

Fig. 1a und 1b

eine perspektivische Seitenansicht einer erfindungsgemäßen Sensoreinrichtung mit einer Reflexionseinheit bzw. eine Querschnitts-Seitenansicht dieser Reflexionseinheit,

Fig. 2a und 2b

eine perspektivische Seitenansicht der Sensoreinrichtung gemäß Fig. 1 mit bezüglich einer ersten Achse verkippter Reflexionseinheit bzw. eine Querschnitts-Seitenansicht dieser Reflexionseinheit,

Fig. 2c

eine Querschnitts-Seitenansicht einer Reflexionseinheit mit im Vergleich zur Reflexionseinheit gemäß Fig. 2b unterschiedlich angeordneten Reflexionselementen, und

Fig. 3a und 3b

eine perspektivische Seitenansicht der Sensoreinrichtung gemäß Fig. 1 mit bezüglich einer weiteren Achse verkippter Reflexionseinheit bzw. eine schematische Draufsicht auf diese Reflexionseinheit.

Further embodiments of the invention are described in the subclaims. The invention is described below using an exemplary embodiment in connection with the figures; in these show:

1a and 1b

2 shows a perspective side view of a sensor device according to the invention with a reflection unit or a cross-sectional side view of this reflection unit,

2a and 2b

2 shows a perspective side view of the sensor device according to FIG. 1 with a reflection unit tilted with respect to a first axis, and a cross-sectional side view of this reflection unit,

Fig. 2c

a cross-sectional side view of a reflection unit with differently arranged reflection elements compared to the reflection unit according to FIG. 2b, and

3a and 3b

2 shows a perspective side view of the sensor device according to FIG. 1 with a reflection unit tilted with respect to a further axis, and a schematic top view of this reflection unit.

1a shows an optoelectronic sensor device according to the invention in perspective side view. This sensor device has a Transmitting element 11 and a receiving element arranged adjacent to it 13, and one arranged opposite these elements 11, 13 Reflection unit 15 with a within a common housing arranged first expansion mirror 17 and second expansion mirror 19th

A transmission light bundle 21 extends from the transmission element 11 in one Transmit beam direction A to the first expansion mirror 17, from which it as a deflecting light bundle 23 in a deflecting beam direction B to the second Expansion mirror 19 is deflected. This deflecting light bundle 23 is from the second expansion mirror 19 in a received beam direction C deflected that it as the receiving light bundle 25, the receiving element 13 acted upon.

In Fig. 1a axes X, Y, Z of an orthogonal coordinate system are also located. The send beam direction A and the receive beam direction C run in opposite or parallel directions to the X-axis, namely spaced apart by an offset distance D. The deflecting beam direction B of the deflected at the first expansion mirror 17 Beam 23 runs in opposite directions parallel to the Z axis, that this light beam 23 and the transmit and receive light beams 21 or 25 U-shaped essentially within a common one Level.

The two expansion mirrors 17, 19 are inside the housing Reflection unit 15 arranged spaced apart from one another along the Z axis. The housing has suitable, not shown in the figures Openings so that the transmit light beam 21 the first expansion mirror 17 act unhindered and the reception light bundle 25 unhindered by the second expansion mirror 19 in the received beam direction C can run.

The two expansion mirrors 17, 19 each have the shape of a part the lateral surface of a cylinder, with the reflective side of the mirror 17, 19 corresponds to the convex outside of this lateral surface. Consequently are two opposite side edges of the two mirrors 17, 19 curved in a circular line, and the other two opposite each other Side edges are essentially parallel and straight to each other. Accordingly, a light beam is expanded 23, 25, which is deflected by one of the expansion mirrors 17, 19, respectively in a direction perpendicular to the beam direction of this light beam 23, 25, namely along the course of the curved side edges and perpendicular to the course of the straight side edges.

The two expansion mirrors 17, 19 are in this way relative to one another and aligned with the light beams 21, 23, 25 that the first expansion mirror 17 and the second expansion mirror 19 each an expansion of the cross section of the deflecting light bundle 23 or of the receiving light bundle 25 in the Y direction, i.e. an expansion of the Cross section along and against the Y axis. The expansion of the Receiving light bundle 25 in the Y direction can be seen in Fig. 1a.

1b shows the reflection unit 15 and the beam path of the light beams 21, 23, 25 in a schematic cross-sectional side view. The straight forward Course of the cross section of the expansion mirror 17, 19 corresponds the course of the two straight side edges.

The sensor device shown in Fig. 1a is used to monitor a between transmitting element 11 and receiving element 13 on the one hand and reflection unit 15 protection area on the other hand. For that it will Transmit light bundle 21 continuously or in a fast manner in a known manner Pulses emitted by the transmitting element 11 while the receiving element 13 continuously or synchronously with the reception of the received light beam 25 monitors. If this reception is due to a Interruption of the transmitted light beam 21 or the received light beam 25 is interrupted, there is an assigned to the sensor device, a corresponding evaluation unit, not shown in FIG. 1a Output signal from, for example a warning, shutdown or control signal.

Fig. 1a shows the sensor device in an ideally adjusted position, i. H. the Beam 21 is transmitted after deflection at the two expansion mirrors 17, 19 as a reception light bundle 25 on the reception element 13 reflects that the longitudinal axis C of the received light beam 25 runs essentially centrally through the receiving element 13.

The one described above for such an adjustment Arrangement of the two expansion mirrors 17, 19 within the reflection unit 15 can be in the manufacture of the sensor device accomplish in a simple manner, since the beam path B, C due to the convex curved design of the mirrors 17, 19 comparatively uncritical for slight deviations from that shown or described Position of the mirrors 17, 19 reacts. Due to the expansion of the Transmit light bundle 21 by means of the first expansion mirror 17 or the Widening the deflecting light bundle 23 by means of the second widening mirror 19 applies even in the event of a deviation in the respective location and Alignment of the mirrors 17, 19 from their ideal position is still sufficient Part of the reflected light beam 23 or 25 is the following one Element 19 or 13.

Similarly, the receiving element 13 remains at a certain level Tilting of the entire reflection unit 15 is still sufficient Way acted upon by the received light beam 25. To explain this advantageous property of the sensor device according to the invention is a tilting of the reflection unit 15 in FIGS. 2a and 2b Y-axis and in FIGS. 3a and 3b a rotation of the reflection unit 15 around the Z axis. These figures show essentially the same Parts of the sensor device according to the invention as in Fig. 1a or 1b shown. Accordingly, these parts have the same reference numerals characterized.

2a and 2b show the sensor device in a perspective side view or the reflection element 15 in cross-sectional side view, wherein the reflection element 15 is tilted with respect to the Y axis. The deflecting light beam 23 and the transmit light beam 21 or the receive light beam 25 are therefore no longer at the angle shown in FIGS. 1a and 1b of 90 ° to each other. The receiving element 13 is still in a measure sufficient to monitor the protection area Receiving light bundle 25 is applied. This is due to the well-known 180 ° reflection a 90 ° roof reflection unit, which the two expansion mirrors 17, 19 due to their relative angle position shown in Fig. 2b of 90 ° to each other. This will make the transmit light beam 21 still ultimately reflected by 180 °.

In the reflection unit 15 according to the invention, the assembly of the two Mirrors 17, 19 compared to conventional reflection units plane mirrors, however, much easier since the beam path B, C of deflecting light bundle 23 and received light bundle 25 due to this Widening is relatively uncritical, especially with large offset distances behaves towards deviations in the relative angle position of the two Expansion mirrors 17, 19 from their ideal position of 90 °. this makes possible Greater tolerances in the manufacture and adjustment of the invention Reflection unit 15.

However, the cross-sectional side view according to FIG. 2b also shows that the offset distance D between the transmitted light beam 21 and the received light beam 25 due to the tilting of the reflection unit 15 and thus the deflecting light beam 23 is shortened, so that the longitudinal axis C of the received light beam 25 with increasing such tilting away from the receiving element 13 in the direction of the transmitting element 11, i.e. migrates along the Z axis.

This effect of the migration of the received light bundle 25 can be caused by a reflection unit 15 according to the invention can be compensated as they is shown in a cross-sectional side view in Fig. 2c. At this Reflection unit 15 is the first expansion mirror 17 compared to that twisted second expansion mirror 19 so that the two straight lines Side edges of the first expansion mirror 17 to the straight line Side edges of the second expansion mirror 19 in a view along make an angle of 90 ° with respect to the Z axis. Accordingly shows the side view of FIG. 2c a curved cross section of the first expansion mirror 17, corresponding to the curved ones Side edges of this mirror 17.

In this arrangement, the first expansion mirror 17 causes an expansion of the cross section of the deflecting light bundle 23 in the X direction.

This widening appears on the second widening mirror after deflection 19 as widening of the reception light bundle 25 in the Z direction, in addition to that caused by the second expansion mirror 19 Expansion in the Y direction. The expansion of the reception light bundle 25 in the Z direction can the explained effect of the migration of the received light beam Compensate 25 from the receiving element 13. Therefore allowed the reflection unit 15 according to the invention due to its design with arched expansion mirrors 17, 19 compared to a known one Reflection unit with flat mirrors a stronger tilt and thus more generous assembly tolerances for the alignment of the reflection unit 15.

3a and 3b show the sensor device according to FIGS. 1a and 1b in one perspective side view or in a schematic top view, wherein the reflection unit 15 is rotated with respect to the Z axis.

While due to the rotation of the reflection unit 15, the received beam direction C with respect to the receiving element 13 in the Y direction is pivoted laterally, the receiving element 13 due to the expansion of the received light bundle 25 in the Y direction is nevertheless subjected to light.

A compensation of such a rotation of the reflection unit 15 is also possible with a conventional triple reflection unit a reflection element as a correspondingly arranged roof edge element is trained. However, this known triple reflection unit is disadvantageously difficult to adjust, especially with large offset distances and especially if it should be possible, different offset distances adjust. In contrast, an expansion mirror 17 requires 19 of the reflection unit 15 according to the invention is only a comparative one low accuracy in its arrangement within the reflection unit 15th

LIST OF REFERENCE NUMBERS

11

transmitting element

13

receiving element

15

reflection unit

17

first expansion mirror

19

second expansion mirror

21

Transmit beam

23

Deflecting light beams

25

Receiving light beams

A

Transmit beam direction

B

Deflecting the beam direction

C

Reception beam direction

D

offset distance

X

axis

Y

axis

Z

axis

Claims (11)

1. An optoelectronic sensor device for the monitoring of a protected zone,
   at least comprising one transmission element (11), one reception element (13) as well as a reflection unit (15) having at least one first reflection element (17) and one second reflection element (19), wherein a transmitted light bundle (21) transmitted along the protected zone from the transmission element (11) to the first reflection element (17) can be deflected along the protected zone by means of the first reflection element (17) as a deflected light bundle (23) to the second reflection element (19) and can be deflected by means of the second reflection element (19) as a received light bundle (25) to the reception element (13),
   characterised in that at least one of the reflection elements (17, 19) is made as an expansion reflector for the deflection and expansion of the relevant light bundle (23, 25).
2. An optoelectronic sensor device in accordance with claim 1, characterised in that the expansion reflector (17, 19) is made as an arched expansion mirror, in particular as a substantially convexly arched expansion mirror.
3. An optoelectronic sensor device in accordance with any one of the preceding claims, characterised in that the expansion reflector (17, 19) is formed for the expansion of the light bundle (23, 25) deflected by it along substantially one single direction perpendicular to the longitudinal axis (B,C) of this light bundle, with the expansion reflector in particular being formed as an arched expansion mirror (17, 19) having substantially the shape of a part of the jacket surface of a cylinder.
4. An optoelectronic sensor device in accordance-with any of claims 1 or 2, characterised in that the expansion reflector is formed for the expansion of the light bundle deflected by it along the total periphery of the cross-section of this light bundle, with the expansion reflector in particular being formed as an arched expansion mirror having two curvatures which are different or the same; and/or substantially having the shape of a part of the surface of a sphere, of a part of the jacket surface of a barrel body, preferably of a circular barrel body, of a part of the jacket surface of a toroid or of a part of the jacket surface of an at least partly aspheric body.
5. An optoelectronic sensor device in accordance with any one of the preceding claims, characterised in that the expansion reflector is formed as a combination of a substantially planar mirror and of a dispersing lens.
6. An optoelectronic sensor device in accordance with any one of the preceding claims, characterised in the that reflection unit (15) has precisely two reflection elements (17, 19); and
   in that the reflection unit (15), on the one hand, and the transmission element (11) and the reception element (13), on the other hand, are arranged substantially opposite one another with respect to the protected zone, with the transmission light bundle (21) and the reception light bundle (25) extending in particular substantially parallel in opposite directions and spaced apart from one another by an offset spacing (D) inside the protected zone.
7. An optoelectronic sensor device in accordance with claim 6, characterised in that both reflection elements (17, 19) are formed as arched expansion mirrors.
8. An optoelectronic sensor device in accordance with claim 6, characterised in that one of the reflection elements is formed as a substantially planar mirror and the other reflection element is formed as an arched expansion mirror.
9. An optoelectronic sensor device in accordance with claim 6, characterised in that one of the reflection elements is formed as a roof edge element and the other of the reflection elements is formed as an arched expansion mirror.
10. A reflection unit (15) having at least one first reflection element (17) and one second reflection element (19) for the deflection by means of the first reflection element (17) to the second reflection element (19) of a transmitted light bundle (21) transmitted from a transmission element (11) to the first reflection element (17) and by means of the second reflection element (19) to a reception element (13), in particular for an optoelectronic sensor device in accordance with any one of the preceding claims,
    characterised in that at least one of the reflection elements (17, 19) is formed as an expansion reflector for the deflection and expansion of the relevant light bundle (23, 25).
11. A reflection unit in accordance with claim 10, characterised in that the expansion reflector (17, 19) is formed as an arched expansion mirror, in particular as a substantially convexly arched expansion mirror.

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