DE3241770A1 - OPTICAL-ELECTRICAL MEASURING DEVICE FOR INCREASED MEASURING SAFETY FOR MEASURING THE POSITION AND / OR DIMENSION OF OBJECTS - Google Patents

Description

\ Dipl.-Ing. Bruno Richter GmbH & Co »Electronic Operations Control Devices KG, Würzburger Strasse 26, 8602 Stegaurach

Optical-electrical measuring device with increased measuring reliability for measuring the position and / or the dimensions of objects

The invention relates to an opto-electrical measuring device for measuring the position and / or the dimensions of objects, in which a sharply bundled light beam is pivoted in a scanning plane by means of a rotating mirror, the pivoting movement of the light beam from collimation means into a parallel displacement movement of the light beam within a measuring field transformed and the light beam beyond the _measurement: field is deflected by focusing means to a detector means out ', so that the light beam from an in-focus area object during the parallel displacement movement for a particular, the size of the cross section in the scanning direction dependent and measurable on the detector output signal time is shadowed. Measuring devices of this type are known from US Pat. No. 3,765,774 or German Offenlegungsschrift No. 2,849,252.

When using such opto-electrical measuring devices ] it is occasionally found that dirt particles are deposited on the collimating means or the focusing means or on other optical parts, which the detector device misunderstood as a measurement object and lead to an incorrect measurement.

324Ί770

Attempts have been made to overcome this difficulty by moving the light beam before it strikes the rotating mirror for example by means of a cylinder lens in the direction parallel to the rotating mirror axis of rotation in cross section tete, in such a way that the rotating mirror does not pivot movements of a single light beam but pivot movements of a light scanning tape generated, which causes the collimation means to • parallel displacement movements within the measuring field became. . ]

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j However, this known measure leads to an increase in j ί the measurement certainty is not the goal if the op- '

'' table components of the measuring device fiber-like, rod-like, or deposit elongated dirt particles in some other way,

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ί which in turn largely reduce the cross-section of the ^! Occupy the light scanning tape and trigger an incorrect measurement.

i, Even if there are disturbing particles in the beam path

not occupy the entire beam cross-section, it can 'come measurements, since the intensity distribution in the bar-shaped I expanded beam cross section due to the uneven' to mis-shaped intensity distribution in the originally scharfgebündelten I. ' Ray is inhomogeneous and consequently the shadowing of a small,; ^: however, with regard to the passage of high light intensities, a significant proportion of the beam cross-section can trigger an incorrect measurement.

The object of the invention is to be achieved, an optically; electrical measuring device of the type specified at the beginning, ensure that incorrect measurements due to interfering particles in the scanning beam path are avoided with greater certainty

: can than is the case with known facilities. !

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! According to the invention, this object is achieved in that the J

A plurality of rotating mirrors in one containing the rotating mirror axis of rotation Planar parallel, sharply focused light ■ beams are directed and by means of the rotating mirror in each other

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ORIGINAL BATHROOM

parallel radial planes to the rotating mirror axis of rotation .be pivoted that the light beam pivoting movements of collimation means each transformed into parallel displacement movements of the individual light beams within the measuring field be that the light rays beyond the measuring field on

! Hit focusing means and from these to a detector- j device are steered, the output signals of which are evaluated to form a common measurement signal.

It can be seen that by using several light beams directed parallel to each other towards the rotating mirror, the light

; intensity distribution within a larger beam cross-section

i tes has no meaning. Rather, several light beams, for example four light beams, can be of essentially the same type : Intensity to be used. Moreover, the mutual

■ Distance of the light rays in the direction of the rotating mirror axis of rotation without great effort in terms of the collimation and focus

; ization to be used optical means comparatively large

\ should be chosen so that the probability of a shadowing! effective jet cross-section even through very large dirt

! particle is small.

] According to a preferred embodiment, the focussing means on the other side of the measuring field direct each of the said scanning light: rays towards a respective associated detector and the each; occasional output signals of the detectors are used to form the; Measurement result processed further.

; In addition, expedient embodiments are the subject of

'pending claims, the content of which is hereby expressly linked to ; Part of the description is made without here : to repeat the wording.

! An exemplary embodiment is described below with reference to FIG

■ the attached, schematic drawing is described in more detail, which shows an optical-electrical measuring device of the type specified here in a plan view and in a simplified form.

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The drawing shows a laser 1 which emits a sharply focused light beam 2 with an extremely small cross section. ! This light beam is directed to an array of beam splitters 3, which have the property of splitting an incident light beam into two output beams, each of which contains \ about 50% of the input energy. The beam splitters 3 generate in this way in cooperation with reflectors 4 in the manner shown in the drawing a total of four small cross-section having scanning light beams 5, which are oriented parallel to each other and all run in a plane which the axis of rotation 6 of a considerable dimension in the direction of the axis of rotation owning rotating mirror 7 are located. The rotating mirror 7 is set in rotation by a motor 8 in such a way that the scanning light beams 5 are caused to pivot about the rotating mirror axis of rotation 6 in planes which are each radial planes to the rotating mirror axis of rotation 6.

After reflection on the rotating mirror 7, the scanning light beams strike on collimation means in the form of a cylindrical lens. The cylindrical lens 9 causes the pivoting movements of the scanning light beams 5 within a measuring field 11 containing a test object 10 in parallel displacement movements in planes are reshaped, which lie parallel to one another at a certain distance and approximately normal to the longitudinal extension of the test object 10 are oriented. In the plan view shown in the drawing, the planes mentioned are represented as straight lines which go through indicated by broken lines and denoted by 12.

ι On the remote from the collimation means side of the test;

lings 10, the measuring field 11 is used as a focusing means I.

serving further cylindrical lens 13 limited, which the scanning j

light rays on individual detectors in the form of |

Photocells 14, 15, 16 and 17 focused. From the initial sig- j

nalen of the photocells 14 to 17 is in a combination unit

direction 18 formed a combined signal that is transmitted via the ι

BATH ORIGINAL

Line 19 is fed to an evaluation device 20. In the evaluation device 20, this combined signal with von ; the drive 8 of the rotating mirror 7 derived and fed via the line 21 timing signals related to to derive a measurement signal corresponding to the position and / or the dimensions of the test object 10 on the basis of the fact that each scanning light beam during its parallel displacement movement within the measuring field 11 for a certain, of the size of the cross section of the test object or object in the scanning direction and in the detector output signals of the photocells 14 until 17 measurable time is shadowed.

; It can be seen that the units 18 and 20 can also be combined into one unit and that the output signals of the photo! cells 14. to 17 can also be individually related to the timing signals j of the line 21, after which the; measurement results obtained in this way, in the present embodiment ^! For example, four measurement results, again evaluated to form a resultant measurement result with high measurement reliability; will.
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[For a redundant evaluation of the signals that can be picked up several times from the photocells 14 to 17, the following procedure is used, for example:

■ Of four separately measured interruption times of the output signals of the photocells 14 to 17 due to a shadowing of the scanning light beam in the measuring field 11 by the test object 10 that time is assigned to the test specimen which is on the one hand the shortest, but on the other hand a certain minimum time exceeds. By defining a minimum time, the effects of small, interfering particles in the measuring field are excluded. The minimum time can be determined automatically, as stated in the German Federal Patent 29 51 677, where the experiences from a previous measuring process in a large number of consecutive measuring processes on and

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the same test item can be used, or the minimum time is set manually at the start of measuring operation.

It should also be mentioned that in order to generate the scanning light beams directed parallel to one another onto the rotating mirror 6, an input | Order of stripe lenses, prisms, light guides and the like! can be used. ·. !

• BAD ORSQIMAL

Claims (1)

Claims IJ Optical-electrical measuring device for measuring the position and / or the dimensions of objects (10) in which a sharp ■ bundled light beam is pivoted in a ί scanning plane by means of a rotating mirror (7), the pivoting movements of the light Beam of collimating means (9) in a parallel displacement movement reshaped within a measuring field (11) and the.! Light beam beyond the measuring field of focusing means (13) I is deflected towards a detector device (14 to 17, 18), I in such a way that the light beam from one located in the measuring field j object (10) during the parallel displacement movement of the light beam in the measuring field for a certain, of the size of the ! Cross-section depending on the scanning direction and on the detector j output signal measurable time is shadowed, thereby marked; net that on the rotating mirror (7) several, in a plane containing the rotating mirror axis of rotation (6) parallel to each other j running, sharply focused light beams (5) are directed and pivoted by means of the rotating mirror in mutually parallel radial planes to the rotating mirror axis of rotation, that the Lichtstrahlj Pivoting movements of the collimation means (9) are transformed into: parallel displacement movements of the individual light beams ι within the measuring field (11) so that the light beam ^; len beyond the measuring field (11) on the focusing means (13)! meet and from these to a detector device (14 to 17, 18); are steered, the output signals of which are evaluated to form a common measurement signal (20). ; 2 ο device according to claim 1, characterized in that the; j sharply bundled light beam that hits the rotating mirror (7) ! len (5) by means of a beam splitter (3) and reflectors (4) from one '. common beam source (1), in particular a laser, '■ be directed. 3. Device according to claim 1 or 2, characterized in that for the pivoted in the said radial planes light ' rays each common Kollimationsitiittel (9) and / or' ! common focusing means (13) are provided. I. 4. Device according to one of claims 1 to 3, marked thereby, characterized in that the focusing means (13) the light rays to a common for all of the radiation detector of the detector '■ ι j device direct from which a resulting measurement signal j j is derivable. j i I : 5. Device according to one of claims 1 to 3, characterized i : shows that the focussing means (13) jets each scanning light onto a respectively assigned detector (14, 15, 16, 17) j the detector device and that the respective output; '■ signals from the detectors processed to form the measurement result' ^: (18) are. : : i i, are 6. A device according to claim 5, characterized in that the i j detectors (14, 15, 16, 17) reasonable to a selector '' ■ ι concluded that the formation of the Meßergbnisses i detector signal is that selects which depends on the Shading, ι of the scanning light beam by the object to be measured (10); 'has a shortest interruption in the detector output signal, however, over a minimum time that can be set automatically. BATH ORIGINAL