Image analysis – Applications – Manufacturing or product inspection
Reexamination Certificate
1998-12-11
2002-06-18
Mancuso, Joseph (Department: 2723)
Image analysis
Applications
Manufacturing or product inspection
C382S153000, C348S087000
Reexamination Certificate
active
06408090
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to a method for positioning recognition of components equipped on a substrate in an automatic equipping unit.
2. Description of the Prior Art
In automatic equipping of substrates (for example, printed circuit boards or ceramic substrates with SMD (surface mounted device components), the individual components are taken from a delivery device with an equipping head and are then positioned on the substrate in a predetermined position.
A check to determine whether all of the components were in fact positioned in their respective predetermined positions ensues indirectly outside the automatic equipping unit. A faulty position of a component after the end of the overall equipping process is thus represented, for example, by a negative electrical function test, i.e. the overall circuit board does not function as intended. At this point, it is virtually impossible to pinpoint the erroneous placement which caused error, and the substrate can no longer be used.
The position of some of the components after the equipping in an automatic equipping unit is checked visually in separate machines outside the automatic equipping unit. In the meantime, however, further components are placed over components that have already been placed on the substrate; the components lying at the bottom are then no longer accessible for a visual check so that, for example, complicated x-ray inspection devices must used.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a simple method for position recognition of components on a substrate which allows the components to be checked early for their actual position.
The above object is achieved in accordance with the principles of the present invention in a method for position recognition of components placed on a substrate in an automatic equipping unit, wherein a predetermined position of the components is stored in a control unit of the automatic equipping unit before placement of the components, the actual position of the components on the substrate is identified using a sensor mounted in the automatic equipping unit, the actual position is compared to the predetermined position, and given agreement, within a predetermined range, between the predetermined position and the actual position, the equipping process is continued, otherwise an error message is generated.
By comparing the actual (placed) position to a predetermined position directly in the automatic equipping unit following the equipping process, separate machines are not required for visual checking. The equipping process is therefore not interrupted and, for example, separate programs for the integrated operation of the separate machine and the automatic equipping unit are not needed.
An additional advantage is that a faulty position is already recognized early, and thus the faulty substrate can be eliminated before additional, cost-intensive equipping processes or other processes as well (soldering) are undertaken.
As warranted, a positional correction—for example, manual—can also be implemented, or the faulty equipping procedure can be repeated given an early recognition of the faulty position.
In an embodiment of the method, a camera having a following image evaluation unit is used as a position sensor. Such sensors as well as the methods for image analysis are technologically mature and are known and allow the position recognition in a simple way.
The method can be used to particular advantage when a component already placed on the substrate is to be covered by another component. The position identification of the first-placed component can then be undertaken while that component is still visible, before placement of the further component over the previously-placed component. In this regard, the term “components” means any type of item which is placed on the substrate, including, for example, cooling elements such as cooling plates as well as electronic components. For saving space, larger components may be placed over smaller components that have already been equipped. As a result of the inventive method, the position of the components lying at the bottom can be identified before the placement of the components lying thereabove, so that complicated x-ray inspections are not needed.
The position sensor can be moved together with the equipping head, allowing every component placed on the substrate to come into the field of view of the sensor. A complicated design of a sensor is thereby avoided.
In a preferred embodiment of the method, the sensor is also employed for identifying the position of the substrate in the automatic equipping unit, so that only one sensor is required for these two processes resulting in cost savings.
The method is preferably employed for optimizing (fine adjustment of) the positional precision of the automatic equipping unit by upon each comparison of the actual position with the predetermined position, conducting a procedure to improve a subsequent placement of another component on the substrate. The positional precision in automatic equipping units can thus be improved from component to component with known optimization (neural network training) algorithms.
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Grasmueller Hans-Horst
Prittmann Jochen
Salomon Werner
Bali Vikkram
Mancuso Joseph
Schiff & Hardin & Waite
Siemens Production and Logistics System Aktiengesellschaft
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