EP1929767A2

EP1929767A2 - Device and method for visually recording two-dimensional or three-dimensional objects

Info

Publication number: EP1929767A2
Application number: EP06754562A
Authority: EP
Inventors: Dieter Klawunder
Original assignee: Modi Modular Digits GmbH
Current assignee: Modi Modular Digits GmbH
Priority date: 2005-06-25
Filing date: 2006-06-26
Publication date: 2008-06-11
Also published as: DE102005029901B4; US20100118121A1; WO2007000293A2; WO2007000293A3; US8164625B2; DE102005029901A1

Abstract

The invention relates to a device (1) for visually recording two-dimensional or three-dimensional objects (2), which comprises a camera (10) for recording images of the two-dimensional or three-dimensional object and which is provided with, can be connected to or is connected to at least one evaluation unit (21) for evaluating the recorded images. A single camera (10) and at least one adjustable or pivotal mirror element (11) are provided. According to the method for visually recording two-dimensional or three-dimensional objects (2, 3) while using a device (1) of the aforementioned type, a camera (10) and at least one adjustable mirror element (11) are arranged relative to one another so that the objects to be recorded are situated in the coverage area of the at least one mirror element. The adjustable mirror element (11) for recording the objects to be recorded is displaced or pivoted about one or two axes (14, 16) with an adjustable velocity. The camera (10) records the objects projected in the at least one mirror element, and the recorded objects are routed from the camera (10) to an evaluation unit (21) for evaluation and are processed.

Description

Device and method for the visual detection of planar or spatial

objects

The invention relates to a device and a method for the visual detection of planar or spatial objects, the device comprising a camera for capturing images of the planar or spatial object and provided with at least one evaluation unit for evaluating the captured images or connectable or connected.

In many cases, products are subjected to quality control after their manufacture in order to detect any defects. Especially for the inspection of surfaces and connections between components, various methods and devices are known in the art, which mostly use several cameras for the investigation. For example, solder joints are tested to the effect that a camera receives a soldered object and makes a decision on the quality of the solder connection via a corresponding evaluation program on a computer. DE 10 2004 004 278 A1 describes a corresponding method and a device. In these, in addition to the camera, a Hanitiervorrichtung is provided to move the soldered object relative to the stationary camera. The handling device takes the board to be assessed and rotates it in front of the camera accordingly.

From DE 697 10 714 T2 is the use of a three-dimensional image detector for performing a line scan in one

Assembly device for electronic components for automatic placement of printed circuit boards with electronic components known. In this case, a displacement of the detection device in the x and y direction over the board to be equipped is provided away.

From DE 697 03 487 T2 an apparatus and a method for the automatic inspection of moving surfaces are known. Here, three different illumination / observation channels are used. Furthermore, methods and devices for testing bottles with a threaded portion are known, for example from DE 696 10 925 T2. In this method, the bottles travel along a high speed road, capturing video images from each bottle, processing the pixels of the respective video image, and examining the pixels in interest areas of interest previously selected to detect thread defects generally around the circumference of the bottle.

DE 203 17 095 U1 discloses a device for detecting defects of an object surface, especially in cast parts, wherein a light source for illuminating the object, a light detector for detecting a beam reflected from the object surface toward the illumination beam and an evaluation unit for evaluating the image data obtained thereby are provided for error detection. In the evaluation, the number of pixels to be examined and the size of the pixel regions to be considered should be kept as low as possible. Among all detected pixels, those are determined whose brightness values deviate from a mean pixel brightness more than a predefinable tolerance value.

The use of a laser beam is also known for scanning a printed circuit board for its examination, e.g. from DE 198 83 004 T1, in which the scanning device consists of two galvanomirrors with mutually orthogonal rotary shafts and a Abtastlinse.

For the quality inspection of wafers, the use of six camera systems is disclosed in DE 103 52 936 A1, wherein two camera systems vertically from the top to the upper edge zone of the wafer, two camera systems from below to the lower edge zone as well as camera systems horizontally on the lateral edge of the wafer are aligned. Defects are detected using an automatic classification.

DE 101 04 355 A1 discloses an apparatus and a method for image scanning of the surface of an object, for use in a painting line for the determination of impurities or defects of the Surfaces of an object. The device comprises a receiving system and a controllable transport means, wherein the transport means along a first horizontal axis relative to the receiving system and the receiving system by means of a displacement means along a second vertical axis can be moved linearly. The recording system includes a camera and lighting.

The prior art devices and methods described above each have the disadvantage that the achievable accuracy of the acquired information is not particularly high and the speed of image acquisition is also quite low. Especially critical image capturing, as in the reading of codes on boards, which are positioned at different locations, is not possible with these devices of the prior art.

The present invention is therefore based on the object, a device and a method for the visual detection of planar or spatial objects to the effect that a comparison with the prior art faster and more accurate detection of objects with little technical effort in a single acquisition process is possible. Especially for the use of the device for detecting

Codes on boards, which are applied to various different locations on the boards, and / or solder joints should be suitably equipped.

The object is achieved for a device according to the preamble of claim 1, characterized in that a single camera and at least one adjustable or pivotable mirror element are provided. For a method according to the preamble of claim 14, the object is achieved in that a camera and at least one adjustable mirror element are arranged to each other so that the objects to be detected are arranged in the detection range of the at least one mirror element, the adjustable mirror element for detecting the to be detected Objects is adjusted or pivoted about one or two axes at an adjustable speed, the camera, the imaged in the at least one mirror element objects recorded, and the detected objects are forwarded by the camera to an evaluation unit for evaluation and processed there. Further developments of the invention are defined in the dependent claims.

As a result, a device for the visual detection of flat or spatial objects is created, which has a non-moving camera. In the present case, a camera is understood to mean a device for converting a captured two-dimensional image into electrical signals. By providing a non-moving camera, the accuracy of the representations over the prior art comprising moving cameras can be significantly increased. When moving a camera during a recording or before and / or after the moving masses must first come to rest before further recording in order to avoid falsification of the recording. However, this is usually not the case, otherwise the recordings take too long to complete. If the accuracy is to be increased or due to the moving mass of the camera, the speed of detection in a moving camera is much lower than with a stationary camera, as in the latter does not accelerate the camera mass and needs to be braked again, which is always a delay the subsequent movement leads. Also, the provision of a moving object to be detected leads to problems in the detection, since it can lead to distortions due to the movement of the object. Furthermore, the structure of such a device is complicated, since a Hantiereinrichtung must be provided for moving the object in front of the camera. By the use according to the invention of a mirror element which can be swiveled quickly and is lightweight relative to the camera as the only moving element, the speed of detecting objects and the accuracy of the detected information can be greatly increased by the suitable choice of its mass compared to the prior art. In this case, speeds of at least 20 objects per second, more preferably 50 objects per second, with an accuracy of 1/100 mm, in particular even 1/1000 mm or even better, are preferably possible. It is also possible to capture less than 20 objects per second, as well as any number of objects greater than 20 or even greater than 50 per second. This is neither with devices of the prior Technique using a plurality of cameras is still possible with prior art devices employing a x and y slidable camera.

In principle, one or more than one mirror element or even a multi-part mirror element can be assigned to a camera if advantages arise in the acquisition of the information about the objects to be detected as a result of the multi-part or the further mirror elements. The acquisition of the data captured by the mirror element or elements by the camera is then adjusted according to the number of mirror elements and their position in space in order to receive all information optimally.

It proves to be particularly advantageous for the camera to be fixed and to provide an adjustment device for the mirror element for adjusting or pivoting the mirror element about two axes. This can do that

Mirror element can be rotated particularly well in a plane around all axis, so that he has at the same time good stability of his movement despite the good mobility. In particular, in this case, the distance to the object to be detected does not change in the z-direction, so that a preset or presettable focusing with respect to the object is maintained in the detection process. With a sufficient distance of the mirror element from the surface of the object, even large objects, such as boards, etc., can be completely detected in a detection step or scan. For example, capturing a 60 x 60 cm surface in one scan is easily possible.

In order to ensure a movement of the mirror element adapted to the object to be detected, a control device is preferably provided for driving the adjusting device for the mirror element with a predefinable or predetermined program. This program can run on a computer associated with or integrated into the device and be adapted to the distance to the object, the desired accuracy of the detection and the type of object and the number of subregions of the object to be detected. Advantageously, the adjusting device comprises at least one device for adjusting the mirror element about the x-axis and at least one device for adjusting the mirror element about the y-axis, wherein the devices can be provided separately or in combination with each other. In particular, it proves to be advantageous, the x-Achseverstelleinrichtung for adjusting the mirror element about the x-axis and / or the y- axis adjustment for adjusting the mirror element about the y-axis motor, hydraulic, pneumatic, magnetic, by temperature changes or by another Type of drive means drivable or driven to design. An adjustment of the angle of the mirror element to the surface to be detected of the object or to the object or objects can be done in a simple manner, under the influence of larger or smaller occurring, the movement braking frictional forces. Especially with a preferred use of a magnetic field for holding and

Adjusting or pivoting the mirror element, a movement is possible almost without a negative influence of frictional forces, since the mirror element is kept floating in space, so to speak.

The mirror element is advantageously designed as a stable mirrored plate, in particular glass, metal or Kunststsoffplatte, formed, in particular with a comparatively low weight, to allow a slight, yet precise movement. Preferably, the mirror element has a very smooth detection surface with a particularly low roughness. As a result, a particularly accurate reproduction of the objects to be detected for detection by the camera is possible. In order to be able to compensate for distortions caused by unevenness on the mirror element, the evaluation unit advantageously has a corresponding compensation device, by means of which the distortions for the evaluation can be compensated.

Preferably, the camera is substantially aligned in a horizontal position approximately parallel to the surface of the object to be detected. In such an orientation, the mirror element or elements can be arranged to one another such that the movement of the mirror element from the camera can be detected very well without the mirror element obstructing the image capture by the camera during its movement.

The camera can be an analog or a digital camera with imaging optics, wherein the choice of imaging optics can be adapted to the particular application suitably. Furthermore, a manually or motor-operated focusing and / or diaphragm adjustment device can be provided in the region of the imaging optics of the camera. As a result, an adaptation to different distances to the objects to be detected is possible.

In order to obtain a particularly good illumination of the surface detected by the at least one mirror element, it is advantageous to provide a lighting device in the region of the camera. It proves to be particularly advantageous to design the illumination device annular, surrounding the lens of the camera, since the lens of the camera is usually aligned optimally with the mirror element in order to be able to record the images captured in it. Due to the reflection of the light in the mirror element, this is redirected to the object and thereby illuminates the areas to be detected on the surface of the object.

The device according to the invention and the method according to the invention can be used in a wide variety of applications. For example, the use of the device for detecting defects on substrates, in particular defective solder joints, missing or incorrectly positioned components, bridges, excess solder, solder bumps, and / or codings proves to be advantageous. Precisely because of the high scanning speed and the thereby possible high accuracy of the recorded data, the device is particularly suitable for more difficult applications, in which errors are difficult to detect or detectable or encodings are alternately provided at various points.

But also in buildings, rooms or on squares, the use of the device according to the invention for monitoring the buildings, rooms or squares, in particular for monitoring a bank hall of a bank, from Department stores, gas stations, power plants or other buildings or rooms to be monitored or for monitoring squares, in particular railway stations, airports, stadiums, etc.

Furthermore, the device according to the invention or the method according to the invention can advantageously also be used, for example, for quality control, in particular for print image control, completeness control of constructed or produced products, connection point control, in particular weld seam inspection, surface inspection or for checking the regularity of other features of a product.

Also for the measurement of objects, in particular components or parts of these, in particular openings, bores, punches or other object parts or objects to be measured or objects, as well as buildings, is the use of the erfindungemäßen device or the inventive method.

The object detection step for detecting the object or objects to be detected may be adjustable at regular or irregular intervals. Preferably, it is adaptable or adapted to the frequency of a change of the objects to be detected. This makes it possible to provide a time-effective detection of the objects, which does not have to be consistent with the respective application, but instead provides an object detection step at intervals. In particular, in the scanning or scanning or detecting objects on a conveyor belt, an adaptation of the frequency of

Detecting and thus the movement of the mirror element made to the speed of the conveyor belt, whereas when monitoring a room, for example, an adaptation to the expected alternating frequency of the objects in this room is provided.

If objects are to be detected by the device according to the invention, which are located alternately at different positions, it proves to be advantageous to provide a device with which the provision of an object recognition step is possible. This is done before the actual scan or object detection step performed to detect the positioning of the object (s) in a database for comparison with a scanned object surface upon detection of object positioning unknown to any object to be read or detected. The position of the objects to be detected is thus stored in a database as a pattern and a comparison made with respect to the known pattern before or at, possibly also after each detection process (scan). If it turns out that the pattern is not yet in the database, a new pattern will be created. Especially when capturing codes on substrates, such as boards, the

Encodings may be alternately provided at different locations, wherein a capturing operation provides for capturing a plurality of encodings on one or more substrates at once. In order to allow the best possible detection or an optimal reading of the codes, their position is optimally previously known, that is detected by an object detection step, so that the reading of these can be done correctly, since the adjusting or pivoting device for moving the mirror element this in moves the appropriate position (s).

Especially when monitoring very large or angularly constructed rooms, several devices can be provided, of which at least one is an inventively designed device with a single camera and at least one of these associated mirror element. Due to the particularly good adjustability of the mirror element, however, large spaces to be detected can be monitored with only one device according to the invention.

In addition to the x-axis adjustment or pivoting device for adjusting or pivoting the mirror element about the x-axis and the y-axis adjustment or -verschwenkeinrichtung for adjusting or pivoting of the mirror element about the y-axis can also be a z-

Axial adjustment for adjusting the mirror element in the z-direction, ie for approaching and removing the mirror element to be detected or from the object to be detected, be provided. If the device is too tight is arranged on the objects to be detected, can occur due to the different distances during the movement of the mirror element blurred when detecting some out of focus set objects and thereby a falsification of the results or an impossible readability. This can be remedied by choosing the largest possible distance to the total area on which the objects to be detected are arranged. As a result, the differences between the distances to the objects to be detected no longer differ in a measure that falsifies the measurement or makes it impossible to read, for example, codes. Instead of selecting a suitable preset or presettable distance to the objects to be detected, the distance can also be changed by the z-axis adjusting device during the movement of the mirror element for detecting and reading out the objects, so that a focusing takes place. In this case, however, care must be taken that capturing the image captured in the mirror element by the camera is still possible and the movement of the mirror element is sufficiently quiet to avoid fuzziness in the image, which can otherwise lead to reading errors or measurement inaccuracies. The evaluation unit may further comprise at least one device for compensating for perspective distortions, so that perspective distortions can be compensated for at least in the evaluation of the captured images in the evaluation unit.

For further explanation of the invention embodiments of this will be described in more detail below with reference to the drawings. These show in:

Figure 1 is a perspective schematic diagram of a first embodiment of an inventive device for the visual detection of flat or spatial objects, in the case illustrated solder joints on boards, and

Figure 2 is a perspective schematic diagram of a second embodiment of an inventive device for the visual detection of planar or spatial objects, in the case shown for reading codes on boards. FIG. 1 shows a perspective view of a first embodiment of a device 1 according to the invention for the visual detection of objects which, in the illustrated case, are boards 2 on a substrate 3. On the substrate to be scanned 20 such boards 2 are arranged, with a review of the solder joints on the boards should be made.

The device 1 comprises a horizontally arranged camera 10 and a mirror element 11. The latter can be adjusted or pivoted by an adjusting or pivoting device 12 in its position, ie it can be the angle to the plane of the substrate 3 and the objects to be detected of the solder joints be changed on the boards 2. The adjusting or pivoting device 12 comprises a device 13 for pivoting the mirror element 11 about the x-axis 14 and a device 15 for pivoting the mirror element 11 about the y-axis 16. By pivoting the mirror element about the x and the y Axis is given sufficient movement to be able to scan all boards on the substrate at a detection step. The devices 13 and 15 may e.g. Motors, in particular stepper motors, pneumatic devices, hydraulic devices, magnetic field generating devices, based on an adjustment by temperature change

Be devices, in particular using heat elements, etc.

The camera is aligned with the mirror element so that it can directly detect the images captured by it, which is indicated by the radiation beams 17 and 18 in FIG. In the basic position before the detection process, in which the mirror element is pivoted about the x and y axis, the camera can be aligned with its lens 19 as imaging optics approximately to the center of the mirror element.

For driving the adjusting or pivoting device 12, a control device 20, which is only indicated in FIG. 1, is provided. Not only does this cause the movement of the devices 13 and 15, but it can also adjust the speed of movement of the mirror element and the extent of its movement about the x and y axes. Axis to the change of the objects to be detected or scanned take place, in particular by the frequency of the scan, so the repetition rate of the object detection steps.

The captured data is forwarded by the camera to an evaluation unit 21, which is likewise only indicated in FIG. This is advantageously also connected to the driving device 19 in order to be able to carry out a new detection step upon detection of erroneous detection of the data before the substrate with the boards is exchanged for another. In this case, a transport device for moving the substrates can also be coupled to the evaluation unit and / or drive device with regard to the speed of the further transport of the substrates, in order here to adapt the individual components to one another and thus to optimally detect the objects to be detected, e.g. to achieve faulty solder joints.

Especially in the detection of faulty solder joints, the pivoting of the mirror element according to the invention proves to be advantageous because a scan is done from different angles and thus shade can be used for evaluation with provision of illumination of the substrate or the boards shadow around the solder joints around.

Instead of checking the boards for possibly defective solder joints, as shown in FIG. 1, a read-out of codes 4 on the boards 2 by the device is provided in FIG. Such codes 4 contain, for example, the production data of products. They can, as indicated in FIG. 2, be differently positioned on the boards and thus also on the substrate, so that reading with a measuring setup known in the prior art is hardly possible. However, it is only by providing the combination of a stationary camera according to the invention and a moving mirror element that readout of the very small codings is possible without problems.

In addition to the embodiments of a device and a method for the visual detection of flat or spatial objects described above and shown in the drawing, numerous other are formed, in each case only a single camera in conjunction with at least one mirror element for quickly detecting a large area or a large space sufficient.

LIST OF REFERENCE NUMBERS

1 device

2 board 3 substrate

4 coding

10 camera

11 mirror element

12 adjusting or pivoting means 13 means for pivoting the mirror element about the x-axis

14 x axis

15 Device for pivoting the mirror element about the y-axis

16 y-axis

17 bundles of rays 18 bundles of rays

19 lens

20 control device

21 evaluation unit

Claims

claims

1. Device (1) for the visual detection of planar or spatial objects (2), which comprises a camera (10) for capturing images of the planar or spatial object and having at least one

Evaluation unit (21) provided for evaluating the captured images or connectable or connected, characterized in that a single camera (10) and at least one adjustable or pivotable mirror element (11) are provided.

2. Device (1) according to claim 1, characterized in that the camera (10) provided fixed and an adjusting or pivoting device (12) for adjusting or pivoting of the

Mirror element (11) about two axes (14,16) is provided.

3. Device (1) according to claim 1 or 2, characterized in that a control device (20) for the adjustment or

Pivoting device (12) for controlling the adjusting or pivoting device for the mirror element (11) is provided with a predetermined or predetermined program.

4. Device (1) according to any one of the preceding claims, characterized in that the adjusting or pivoting device (12) at least one means (13) for adjusting or pivoting the mirror element (11) about the x-axis (14) and at least one Means (15) for adjusting or pivoting the mirror element (11) about the y-axis (16), wherein the means (13,15) are provided separately or in combination with each other.

5. Device (1) according to one of the preceding claims, characterized in that the x-axisverstell- or -verschwenkeinrichtung (13) for adjusting or pivoting of the mirror element (11) about the x-axis and / or the y-axis adjustment or -verschwenkeinrichtung (15) for adjusting the mirror element (11) about the y-axis (16) is driven or driven by motor, hydraulic, pneumatic, magnetic, by temperature changes or by another type of drive means or are.

6. Device (1) according to any one of the preceding claims, characterized in that the camera (10) is aligned substantially in a horizontal position approximately parallel to the surface of the object to be detected.

7. Device (1) according to one of the preceding claims, characterized in that the camera is an analog or a digital camera with imaging optics.

8. Device (1) according to claim 7, characterized in that a manually or motor-operated focusing and / or

Aperture adjustment is provided in the field of imaging optics of the camera.

9. Device (1) according to one of the preceding claims, characterized in that a plurality of devices (1) are provided, of which at least one single camera (10) and at least one of these associated mirror element (11).

10. Device (1) according to one of the preceding claims, characterized in that a lighting device in the region of the camera (10) is provided.

11. Device (1) according to claim 10, characterized in that the illumination device is annular and surrounds the lens (19) of the camera (10).

12. Device (1) according to one of the preceding claims, characterized in that a z-axis adjustment is provided for adjusting the mirror element in the z direction for approaching and removing the mirror element to be detected or by the object to be detected.

13. Device (1) according to one of the preceding claims, characterized in that the evaluation unit (21) comprises at least one means for compensating for perspective distortions.

14. A method for the visual detection of flat or spatial objects (2,3) using a device (1) according to any one of the preceding claims, characterized in that a camera (10) and at least one adjustable mirror element (11) are arranged to each other that the objects to be detected in

Detection area of the at least one mirror element are arranged, the adjustable mirror element (11) for detecting the detected

Objects around one or two axes (14,16) with an adjustable

Speed is adjusted or pivoted, the camera (10) detected in the at least one mirror element (11) detected objects, and the detected objects from the camera (10) to an evaluation unit (21) forwarded for evaluation and processed.

15. The method according to claim 14, characterized in that the adjustment or pivoting of the at least one mirror element (11) takes place at a high speed of at least 20 objects per second.

16. The method according to claim 15, characterized in that the adjustment or pivoting of the at least one mirror element (11) takes place at a speed of 50 objects per second.

17. The method according to any one of claims 14 to 16, characterized in that the accuracy of the detection is at least 1/100 mm, in particular 1/1000 mm.

18. The method according to any one of claims 14 to 17, characterized in that the object detection step for detecting the object or objects to be detected is adjustable at regular or irregular time intervals, in particular adapted to the frequency of a change of the objects to be detected or adapted.

19. The method according to any one of claims 14 to 18, characterized in that upon detection of an unknown with respect to be read or to be detected objects positioning of the objects

Object detection step is performed before the object detection step.

20. Use of the device (1) according to one of claims 1 to 13 for detecting defects on substrates, in particular faulty

Soldering, missing or incorrectly positioned components, bridges, Lotüberschuss, solder bumps, and / or encodings.

21. Use of the device (1) according to one of claims 1 to 13 for monitoring buildings or rooms, in particular for monitoring a bank hall of a bank, department stores, gas stations, power plant halls or other spaces to be monitored, or of squares, in particular stations, airports , Stadiums.

22. Use of the device (1) according to one of claims 1 to 13 for quality control, in particular for print image control, completeness control of constructed or produced products, connection point control, in particular weld seam inspection,

Surface inspection or to check the regularity of other characteristics of a product.

23. Use of the device (1) according to one of claims 1 to 13 for the measurement of objects, in particular components or parts of these, in particular openings, bores, punches or other object parts to be measured.