Recently, there is an increasing tendency to utilize visual recognition apparatuses in packaging machines and the like, as an application of a sensing technology for positioning electronic components to be mounted on circuit boards through feedback control, thereby producing circuit boards of higher package density.
A conventional visual recognition apparatus will hereinbelow be described with reference to the accompanying drawing.
FIG. 4 schematically illustrates the arrangement of the conventional visual recognition apparatus. In the figure, a retainer 1 retains a subject 2 to be recognized, such as an electronic component supplied to the industrial automated system. Indicated at 3 is a lighting element and at 4 is a camera.
Now referring to FIG. 4, description will be given on the operation of the visual recognition apparatus of the above arrangement.
First, the retainer 1 takes up by sucking or gripping an electronic component, as the subject of recognition 2, from a predetermined component supply section (not shown). Subsequently, as holding the subject of recognition 2, the retainer 1 moves into a field of view of the camera 4, where the retainer 1 stands still at place until an image of the recognition subject 2 is picked up by the camera. At this time, the subject of recognition 2 is illuminated by the lighting element 3 so as to be given a sufficient brightness to be photographed by the camera 4. The camera 4, in turn, acquires the image of the recognition subject 2 in a rectangular frame, which includes the recognition subject 2 against the retainer 1 as a background. The image thus acquired is committed to an image recognition processing. A position and an attitude of the recognition subject 2 is determined based on the processed image and the results are used for positioning the recognition subject 2 on a circuit board.
In the conventional visual recognition apparatus of the above arrangement, however, the retainer 1 holding the subject of recognition 2 is also irradiated with light from the lighting element 3. Accordingly, the image acquired by the camera 4 also includes an image of the retainer 1. This causes an error in extraction of the recognition subject 2 committed to the image processing. To over come such a drawback, a black coating is usually applied to the surface of the retainer 1 for minimizing light reflection from the retainer 1. Unfortunately, the light reflection is affected by the characteristic or finishing of the coating. Therefore, it is impossible to completely eliminate the light reflection from the retainer 1. This results in the impossibility of preventing the retainer 1 from being photographed along with the recognition subject 2.