Optics: measuring and testing – Dimension – Width or diameter
Reexamination Certificate
2000-05-19
2003-03-04
Pham, Hoa Q. (Department: 2877)
Optics: measuring and testing
Dimension
Width or diameter
C356S606000, C356S623000
Reexamination Certificate
active
06529283
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention concerns a device for measuring the gap width between two structural components, wherein the gap is delimited by the edges of the structural components, comprising
illumination means for illuminating the structural components;
detection means for detecting reflections from the structural components in the area of the gap caused by the illumination means; and
evaluation means for evaluating the detected reflections and for determining the width of the gap.
The invention also concerns a gap measuring arrangement for measuring the width of gaps between the leaves or the rest of the body of a vehicle, wherein the gaps are limited by edges of the leaves and/or the rest of the body.
Finally, the invention concerns a method for measuring the gap width between two structural components, the gap being delimited by the edges of the structural components, wherein
the structural components are illuminated by illumination means;
the reflections, generated by the illumination means on the structural components in the area of the gap are detected;
the detected reflections are evaluated and
the width of the gap is determined.
Devices of the above mentioned kind are used in various fields. Such devices are widely used e.g. in the automotive industry for measuring the width of gaps between the leaves or the rest of the body of a vehicle. The gaps are delimited either from both sides by edges of the leaves or from one side by an edge of a leaf and by the rest of the body at the other side. In the following, leaves designate parts of the body of a vehicle hinged in a pivotable fashion to the rest of the body. In the case of an automotive vehicle, these are, in particular, the doors, the hood and the trunk.
During manufacture of a vehicle, the correct position and location of the leaves relative to the rest of the body is checked several times. Directly after mounting of the leaves, one examines e.g. whether or not the leaves are properly fitted to the rest of the body. The first check is performed before the body is painted. Depending on the material from which the body is made, the body has a mat, untreated steel, aluminium or plastic surface. These different surface materials have widely varying reflection characteristics. The normally mat body surface reflects light poorly.
During final inspection of the vehicle, the gap width between the leaves or the rest of the body is again examined at a plurality of measuring points. For this final examination, the body has been painted. Depending on the color of the paint, the body surface has differing reflection properties.
Various conventional devices and methods have been used for measuring the gap width. Due to their easy handling and high measurement speed, feeler gauges of differing widths have become established in the automotive industry. By inserting various feeler gauges into the gap, that feeler gauge is determined which precisely fits into the gap. From the width of this feeler gauge, one obtains the width of the gap. The measurement results which can be achieved with this method, are not very accurate. With gap widths in the range of less than 10 mm, the measurement result depends e.g. on the angle at which the feeler gauge is introduced into the gap.
Moreover, the measurement results which can be achieved with this method are not reproducible. With this method, different individuals obtain different measurement results for the same gap. Different automotive vehicle manufacturers measure the gap width of their vehicles at different measuring points and in different ways. For this reason, different automotive vehicle manufacturers may obtain completely different measurement results for identical gap widths. The measurement value of the gap width between the leaves or the rest of the body obtained with the conventional method can therefore not be used as a comparative value for assessment of the production qualities of various automobile manufacturers.
Prior art discloses a further method of measuring the gap width between two structural components, referred to as edge detection, wherein the gap is delimited by the edges of the structural components. In this method, illumination means illuminate the structural components in the area of the gap. Illumination of the structural components causes strong surface reflections on the surfaces of the structural components. The gap absorbs the light emitted by the illumination means. Detection means detect the light/dark transition on one side of the gap and the dark/light transition on the other side of the gap. Evaluation means evaluate the detected reflections and determine the width of the gap.
This conventional method can function with sufficient accuracy only if the light/dark transition or the dark/light transition is clearly visible and can be clearly detected by the detection means. This requires relatively good reflection properties of the surfaces of the structural components. Such good reflection properties can only be effected by very smooth surfaces. Reflections from untreated metal surfaces are too weak for this method. Towards this end, the edge detection method cannot be used for checking proper fitting of the leaves to the rest of the body.
In addition, the surfaces have different reflection properties in dependence on their color. The conventional edge detection method thereby produces different measurement results for the same gap width, in dependence on the color of the surface of the structural components defining the gap. Since vehicle body are painted in a large number of different colors, the conventional edge detection method cannot be used in the automotive industry for final inspection to check the width of gaps between the leaves and the rest of the body parts of a vehicle.
It is therefore the underlying purpose of the present invention to design and further develop a device of the above mentioned kind in such a manner that the gap width between two structural components can be measured in a simple, reliable, accurate, and reproducible manner independently of the surface finish of the structural components.
SUMMARY OF THE INVENTION
Departing from the device of the above mentioned kind, this object is achieved in accordance with the invention by disposing and orienting the illumination means and the detection means relative to one another and relative to the gap such that the detection means detect line-shaped reflections on the edges of the structural components delimiting the gap.
With the device in accordance with the invention, the line-shaped reflections are detected at the edges of the structural components delimiting the gap. The illumination means must therefore be disposed and oriented relative to the gap in such a manner, that at least part of the light beams emitted by the illumination means is reflected as line-shaped reflections at the edges of the structural components. The detection means must be disposed and oriented relative to the gap such that they can detect these line-shaped reflections. In addition, the illumination means and the detection means must be disposed relative to the structural components in such a manner that the detection means do not detect a virtual reflected image of the illumination means.
The detection means detect the line-shaped reflections at the edges of the structural components. More precisely, they detect a dark/light/dark transition between the structural component (dark), the line-shaped reflection (light), and the gap (dark), or vice versa. The line-shaped reflections are generated at edges having an edge radius which may be very small. The line-shaped reflections occur even with relatively sharp-edged edges. The line-shaped reflections also occur for relatively poorly reflecting surfaces such as mat untreated metal surfaces. The position of the line-shaped reflections at the edges does not depend on the reflection properties of the surface.
The device in accordance with the invention permits measurement of the gap width between two structural components in a simple, reliable
Demopoulos Andreas
Tassakos Charalambos
inos Automationssoftware GmbH
Pham Hoa Q.
Vincent Paul
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