WO1996001976A1

WO1996001976A1 - Device for recording changes in position or movements over short distances

Info

Publication number: WO1996001976A1
Application number: PCT/DE1995/000862
Authority: WO
Inventors: Uwe Engberts
Original assignee: Uwe Engberts
Priority date: 1994-07-09
Filing date: 1995-07-06
Publication date: 1996-01-25
Also published as: AU2920295A

Abstract

The invention relates to a device for recording changes in position or movements over short distances of less than a few millimetres, preferably distances of fractions of a millimetre, and especially a device for monitoring at least one force acting on an object and resulting in a relative movement. The aim of the invention is to provide a device of the aforementioned design which is relatively economical to produce, ensures great accuracy, is easy to set up, maintain and calibrate and is capable of detecting forces or movements even in different directional components. This aim is reached by a device in the form of a sensor arrangement consisting of a transmitter for electromagnetic radiation and a receiver therefor, in which the transmitter and receiver are spaced apart.

Description

Device for registering changes in position or movements over short distances

The invention relates to a device for registering changes in position or movements over distances of less than a few millimeters, preferably over distances of fractions of a millimeter, in particular a device for monitoring at least one force acting on an object and leading in any case to a relative movement.

Basically, devices of the type mentioned at the outset are known, for example as so-called "strain gauges", by means of which e.g. Weight forces or other loads or movements or changes in position that occur as a result are to be registered.

Other devices take advantage of the piezoelectric effect, for example.

Such devices have preferred directions due to their design, in which they can register forces or movements.

But also outside the area of force measurement it is important to register the smallest movements or even to implement them electrically. An example of this is a microphone in which acoustic waves lead to small relative movements of microphone elements, which in turn are registered, recorded or converted into movements at another location, for example in the area of a loudspeaker.

Known devices of the type mentioned are often either relatively inaccurate or relatively complicated and costly to achieve higher accuracy. The maintenance and calibration of such devices is often not easy.

The invention has for its object to show a device of the type mentioned, which is relatively inexpensive, ensures high accuracy, easy to arrange, maintain and calibrate and can possibly also detect forces or movements in different directional components.

This object is achieved according to the invention by a device which is distinguished by a sensor device comprising a transmitter for electromagnetic radiation and a receiver for this radiation, the transmitter and the receiver being arranged at a distance from one another so that there is a space between them a movement path that runs approximately with respect to the radiation of a movement body suitable for partially interrupting the radiation region and performing or indicating the change in position or the movement.

In a simple case, the sensor device according to the invention could be a light barrier, as shown in FIG a preferred development is also provided according to the invention.

In the radiation path of the sensor device essentially either the object that is moving at all or a moving body, quasi a pointer, which reflects the movement of another object, because it is coupled to this object in some way, for example.

In the context of a special embodiment of the device according to the invention for monitoring at least one force acting on an object, in particular a force that changes with time, the movement body is designed as an interrupter for the light path of a light barrier, which is oriented with its free end section, approximately transversely to the light path, partially immersed in the light path and partially blocked.

With a monitoring device designed according to the invention, a surprisingly precise registration of forces is possible. The interrupter and the light barrier are arranged at a distance from one another on the object on which forces act, and at such a distance from one another that the free end section of the interrupter can dip into the light path and thus partially obscure the light transmitter from the light receiver. For this purpose, the interrupter can in principle be of any length, for example as a strip-shaped pointer.

If forces occur on the object on which the interrupter and the light barrier are arranged, there are relative movements between the interrupter and the

Photo eye, because the object is for example bends, stretches or compresses. As a result, the occlusion or the interrupted area of the light path through the interrupter is changed, namely continuously changed, which an analog light barrier in particular can register very precisely on the basis of the respective light reception. It is quite conceivable to quantitatively detect path changes of the interrupter of approximately 0.01 micrometers.

0 Even relatively stiff and solid objects can be changed by such short distances by forces that are not so high, i.e. bent, stretched or compressed. As a result, the device according to the invention can be used in a simple manner, for example to register 5 occurring forces on machine tools, which could generally be reaction forces of the tool actuation, as a result of which conclusions could be drawn about the activity of the tool. However, a device according to the invention could, for example, also be arranged on cranes or the like in order to monitor weight loads which could lead to changes in the shape of the crane construction. Another possibility would be e.g. in arranging a device according to the invention on a workpiece at 5 machining it and e.g. thereby checking the processing progress.

Outside the area of the force registration, the movement body could also be coupled, for example, to the membrane of a microphone, as a result of which the membrane movements could be registered very precisely and further processed electrically. Also e.g. Purposes in optics would be conceivable.

5 The interrupter or the moving body can be in various orientations on an object to be ordered. Accordingly, movements or forces that act in different directions could be registered.

An alternative embodiment of the device according to the invention, again based on the type mentioned at the outset, is characterized by a sensor device comprising at least one transmitter for electromagnetic radiation and at least one receiver for this radiation, the transmitter and the receiver for changing the width of the overlap the transmission area and the reception area are arranged to be movable relative to one another.

For many purposes, a moving body is not required or is very difficult to provide. In such a case, it may be sufficient if the movement takes place between the elements of the sensor device itself, that is to say the transmitter and the receiver move relative to one another. The resulting change in the overlap of the transmission area and the reception area leads to a corresponding change in the output signal of the receiver, so that this relative movement can also be registered very precisely and implemented electrically.

A particularly precise registration is possible if, as provided in accordance with a further development of the invention, two receivers arranged next to one another in the transmission range of the transmitter are used, in particular if these two receivers are switched in opposite directions to one another.

The change in the overlap of the transmission area and one of the two reception areas then inevitably leads to a corresponding change in the Overlaps with the other reception area so that this change is checked twice. This change can be seen particularly precisely if the receiver and the transmitter are aligned with one another in such a way that in a zero position both receivers each have the same transmission power and the two receivers work in opposite directions, i.e. in the zero position the received signals cancel each other out and a zero line is actually set . The slightest change in the positions of the receiver and transmitter relative to one another then leads to a very precisely recordable total output of the two receivers.

However, the measure of the two receivers arranged next to one another and preferably working in opposite directions means not only an improvement in the accuracy in the case of receivers moving relative to one another on the one hand and transmitters on the other hand, but also when using a moving body between the receivers and the transmitter.

With such a device, it is no longer necessary for the moving body to be immersed in the radiation area as an interrupter and to cover it more or less as a percentage due to its position and .length or width, but it may also be possible to do more when using two receivers needle-shaped moving bodies are used which run parallel to the parting plane between the two receivers. The smallest movements of such a needle shape can be registered, namely depending on whether the larger part of this needle is in the reception range of one receiver or the other receiver. In particular, very fine movements can be registered through the parting plane of the two adjacent receivers. A further development of the invention provides that the device comprises a reference receiving unit for regulating and controlling a standard transmission power of the transmitter. With the aid of the reference receiver, the transmission power of the transmitter is always controlled and kept stable, in order to be able to assume a constant transmission power, particularly in the case of successive comparative measurements. As a result, component characteristics are also advantageously negligible with regard to their possibility of error sources. Soiling or other changes to the transmitter or receiver can also be compensated for.

A reference receiver is not absolutely necessary to control the transmitter. If a transmitter faces two receivers, the difference in the output signals of the receivers could be used to register changes in position, while the sum of the output signals can serve to control the transmitter and as a kind of reference signal.

In a simple case, the transmitter can be a light-emitting photodiode and the receiver can be a photocell.

Further advantageous configurations result from subclaims 9 to 18.

The interrupter and the light barrier can have brackets which are separate from one another and can thus be arranged on the object separately from the outset, so that a relative movement between the shape of the object is immediate the light barrier and the interrupter enters. The interrupter and the light barrier can also be preassembled on a common carrier, which in turn can be arranged on the object. The carrier itself is subject to the same forces as the object itself, so that sufficient relative movements between the light barrier and the interrupter can occur even with such an arrangement. The occurring relative movements on the object itself are hardly falsified by the wearer if the wearer is flexible. It may well be considered to form the carrier, for example, from an elastic material, for example as a rubber mat or the like, but it can also be provided that the carrier has at least at least one weakening range between the point of application of the interrupter and the point of application of the light barrier in terms of its flexural rigidity and / or its tensile strength is weakened, the interrupter protruding beyond this weakened area.

For this purpose, for example, the carrier element could be made thinner in the weakened area, for example by A material recess is provided in the weakened area. However, the carrier can also be designed to be resilient, for example in the weakened area, for example by is folded in the broadest sense, with, for example, an additional thinner material taking a meandering or accordion-like course.

Of course, in addition to the sensor device, the monitoring device according to the invention must include evaluation electronics and the like, by means of which the light fluctuations which result from the movement of the interrupter can be detected and evaluated. In principle, however, this is conventional - 9 -

Sufficient technology is available, for example by semiconductor technology, by oscilloscopes, multichannel analyzers, computers or the like.

An exemplary embodiment from which further inventive features result is shown in the drawing. Show it:

1 is a side view of an embodiment of a sensor device according to the invention,

2 shows a top view of the sensor device according to FIG. 1,

3 shows the output signal of the light barrier of the sensor device shown in FIGS. 1 and 2 over time for monitoring time-limited forces,

4 shows a further embodiment of a device according to the invention with a sensor device with a more needle-shaped moving body in plan view,

5 shows the device according to FIG. 4 in a side view and

Fig. 6 shows another embodiment of a device according to the invention with mutually relatively movable receiver and transmitter units.

1 shows a side view of an exemplary embodiment of a sensor device according to the invention of a monitoring device according to the invention. The sensor device comprises a light barrier with a light transmitter 1 and a light receiver 2, of which only the light transmitter 1 is shown in FIG. 1 and the light receiver 2 is omitted for better insight.

In addition, the sensor device comprises a strip-shaped interrupter 3 which, with its free end, which is formed obliquely in the exemplary embodiment shown, plunges into the light path between the light transmitter 1 and the light receiver 2 and partially, namely approximately half, interrupts this light path .

The light barrier, consisting of light transmitter 1 and light receiver 2 on the one hand, and the interrupter 3 on the other hand are mounted with different points of attack on a carrier 4 at a distance from one another which is bridged by the interrupter 3. Between the two areas of attack of the light barrier 1, 2 and the interrupter 3, the carrier 4 has a weakened region 5 in which the carrier is designed to be resilient. For this purpose, the material of the carrier 4 is made thinner in this area and folded in the broadest sense by taking a meandering or accordion-like course in the side view.

The carrier 4 can in turn be arranged with the aid of fastening screws 6 on a surface of an object to be monitored. If forces act on this object, they also lead to changes in shape of the carrier 4, in particular through the weakened region 5 of the carrier 4, in that the carrier 4 stretches, compresses or bends. This results in relative movements between the interrupter 3 and the light barrier 1, 2, so that the light enters the Light receiver 2 changes (continuously).

For the weakening in the weakening area 5, the carrier 4 could also simply have a material cut-out, so that, as indicated by dashed lines 7, it is only thinner in this area. The carrier 4 shown can be made of metal, for example.

An even greater relative mobility between the interrupter 3 and the light barrier 1, 2 can be achieved in that the carrier 4 is completely severed, for example in the area of the dash-dotted line 8, so that brackets for the interrupter 3 and the light barrier 1 to be arranged separately are 2 arise.

Another possibility would also be to form the carrier 4 from an elastic material, for example as a rubber strip or the like.

2 shows a top view of the

1. The same components are denoted in this figure with the same reference numbers as in FIG. 1.

3 shows qualitatively the approximate course of the output signal of the light barrier 1, 2, in particular of the light receiver 2, as a function I (t) or generally as a function X (t) of the time t, if a force on the object is present for a relatively short time acts on which the sensor device shown in FIGS. 1 and 2 is arranged when this force also leads to a relative movement between the interrupter 3 of the light barrier 1, 2, so that the interrupter 3 allows a larger amount of light to pass briefly via the light path. This course of the function thus corresponds qualitatively to that Course of the acting force F as a function of time t itself.

If, for example, two forces that follow one another in time are to be compared with one another in terms of their effect on the object and thus on the sensor device, the function I shown in FIG. 3 could be integrated for both forces in a period between a time t1 and a t2 and the area integral obtained in this way is compared quantitatively with the two forces. In principle, the fixing of the times t1 and t2 is arbitrary and only has to be equated for both forces to be compared. It is advisable, however, to set the times in such a way that either the maximum of the force or, as shown in FIG. 3, the increase before the maximum is recorded, because such time ranges are particularly meaningful and in comparison the highest percentage Ensure accuracy.

If, as in the case described above, two successive forces are compared with one another, this has the particular advantage that only a relative measurement and evaluation is carried out, in which possibly existing systematic errors and possibly also other sources of error are eliminated.

4 shows a top view of a further embodiment of a device according to the invention.

The same components are designated with the same reference numbers as in the previous figures.

In this embodiment, the carrier 4 has a U shape on. On the legs of this U-shape, a light transmitter 1 and two light receivers 2 arranged opposite and next to one another are arranged on the inside. The light receivers 2 work in opposite directions to each other. Between the light transmitter 1 and the light receivers 2 there is a movement body 3, which in this exemplary embodiment is more needle-shaped and is oriented transversely to the legs of the carrier 4, that is to say parallel to the parting plane between the two light receivers 2. The movement of the movement body would preferably be parallel to the legs of the carrier 4, that is to say transversely to the longitudinal extent of the movement body 3 and transversely to the parting plane between the light receivers 2. This movement or change in position of the body 3 would make it more of the reception area of the one receiver 2 and slightly more cover the other light receiver 2. This change can be registered very precisely on account of the light receivers 2 working in opposite directions, and also in their chronological sequence, not only with regard to the movement path.

In addition, the device according to FIG. 4 has a reference receiver 9, which checks the transmission power of the light transmitter 1 as continuously as possible and regulates it to a standard value by means of control electronics.

FIG. 5 shows the device according to FIG. 4 in a side view.

6 shows a further exemplary embodiment of a device according to the invention. Again, the same components are designated with the same reference numbers as in the previous figures. The sensor device, consisting of a light transmitter 1 and two light receivers 2 working in opposite directions to one another, is in principle constructed in exactly the same way as the device according to FIG. 4. This device also has a reference receiver 9.

In contrast to the previous exemplary embodiments, however, this device does not require an interrupter or moving body 3. The light transmitter 1 and the light receiver 2 are rather mounted on two separate supports or holders 4, so that the light transmitter 1 and the light receiver 2 move relative to one another can, whereby the overlap of the transmission range of the light transmitter 1 with the respective 5 reception area of each light receiver 2 changes with the movement. The carriers 4 can be connected to objects or objects 10, the relative movement of which is actually to be registered. The indicated objects 10 can, however, also only be regions of a single object 10, which, for example, carry out relative movements to one another by compressing the object or the like.

The reference receiver 9 is gem. 4 5 and 6 are suitable to compensate for any errors that may occur, for example also errors that could occur, for example, due to temperature fluctuations, aging processes or other faults.

Claims

Expectations:

1 -Device for registering changes in position or movements over distances of less than a few millimeters, preferably over distances of fractions of a millimeter, in particular a device for monitoring at least one force acting on an object and leading in any case to a relative movement, characterized by a sensor device consisting of a transmitter for electromagnetic radiation and a receiver for this radiation, the transmitter and the receiver being arranged at a distance from one another, so that between them there is a space for a movement path that is approximately perpendicular to the radiation of a position change or movement that carries out or indicating moving body suitable for partially interrupting the radiation area.

2.Device for registering changes in position or movements over distances of less than a few millimeters, preferably over distances of fractions of a millimeter, in particular a device for monitoring at least one force acting on an object and leading to an in any case relative movement, characterized by a sensor device consisting of at least one transmitter for electromagnetic radiation and at least one receiver for this radiation, the transmitter and the receiver being arranged so as to be movable relative to one another in order to change the width of the overlap of the transmission area and the reception area.

3.Device to claim 1 or 2, characterized in that it has two receivers arranged side by side in the transmission area of the transmitter. 4 device according to claim 3, characterized in that the two receivers are connected to work in opposite directions.

⁵ 5.Device according to claim 3 or 4, characterized gekenn¬ characterized in that the receiver and the transmitter are aligned so that in a zero position, both receivers each hit the same transmission power.

106. Device according to one or more of the preceding claims, characterized by a reference receiving unit for regulating and controlling a standard transmission power of the transmitter.

5 7.Device according to one or more of the preceding claims, characterized in that the transmitter is a light-emitting photodiode (LED) and the receiver is a photo cell, which together form a light barrier.

0 8 device for monitoring at least one force acting on an object, in particular a force changing over time, preferably according to claim 1, characterized by 5 an (analog) light barrier with a light path between a light transmitter (1) and a light receiver (2) for arrangement in an area of the object and by an area to be arranged in a spaced area of the object, as an interrupter (3) for the light path of the light barrier (1, 2), which is oriented with a free end section, approximately transversely to the light path, partly in immerses the light path and partially blocks it, trained movement body.

5 9.Vvorrichtung according to claim 8, characterized in that the interrupter (3) as an approximately strip-shaped pointer is trained.

10. The device according to claim 8 or 9, characterized gekenn¬ characterized in that the interrupter (3) is provided for arrangement on the 5 object parallel to a surface of the object.

11 - Device according to one or more of the preceding claims, characterized in that the moving body and the sensor device or the transmitter and the receiver, as elements which can be moved relative to one another, have separate mounts for attachment to the object.

15ι 2.Device according to one or more of claims 1 to 10, characterized in that the moving body and the sensor device or the transmitter and the receiver are preassembled as elements which can be moved relative to one another on a common carrier (4), which in turn

20 can be arranged on the object.

13.The device according to claim 12, characterized in that the carrier (4) is flexible.

2514.Apparatus according to claim 13, characterized in that the carrier (4) in at least one weakening area (5) between the point of application of one movable element and the point of application of the other movable element in its

30 flexural rigidity and / and its tensile strength is weakened.

15.The device according to claim 1 and 14, characterized gekenn¬ characterized in that the interrupter (3) formed 35 movement body projects beyond the weakened area (5) of the carrier (4). 16.The device according to claim 14 or 15, characterized gekenn¬ characterized in that the carrier (4) in the weakened region (5) is relatively thin.

⁵ 17. Device according to one of claims 14 to 16, characterized in that the carrier (4) in the weakened area (5) is resilient.

18.Device according to claim 13 or 17, characterized in that the carrier (4) in the weakened area (5) is folded in the broadest sense.