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AssigneeUnova U.K. Limited
InventorsMark Andrew Stocker, Dermot Robert Falkner, Paul Martin Howard Morantz, Michael George Pierse
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A workpiece alignment and shifting system for moving circular workpieces from a first inspection station to a second machining station, comprises workpiece holding means for attachment to the face of a disc workpiece to move the latter from one position to another. Robotic means controls the position of the workpiece holding means and is adapted to move in a least two orthogonal directions, both of which are parallel to the plane of the disc when it occupies the first station. The disc is rotated in the inspection station and in the machining station and inspection means determines the position of the geometric center of the disc as it is rotated. Computing means calculates from data delivered by the inspection means the two shifts required along the orthogonal directions of movement of the robotic means, to move the geometric center of the disc to a second desired position whose coordinates are known. The computing means includes memory means for storing the said coordinates. The coordinates are those of the center of rotation of the workpiece holder or chuck in the said second station. The workpiece holding means is vacuum operated. A three axis robot is employed to pick and place disc-like wafers of semi-conductor material for edge grinding, and movement along two of the robot axes, X and Z, is used to control the centering of the wafer on a vacuum chuck in the second grinding station.
A machine for edge grinding circular workpieces, comprising workpiece holding means for attachment to the face of a workpiece to move the latter from one position to another, robotic means controlling the position of the workpiece holding means and adapted to move in at least two orthogonal directions, both of which are parallel to the plane of the workpiece when it occupies an optical inspection station, means for rotating the workpiece in the inspection station and in a machining station, inspection means for determining the position of the geometric centre of the workpiece as it is rotated in the first station, and computing means for calculating from data delivered by the inspection means any shifts required along the orthogonal directions of movement of the robotic means, to move the geometric centre of the workpiece to a second desired position whose coordinates are known, the optical inspection means comprising a CCD camera having its optical axis parallel to the axis of the workpiece and which forms an optical image of the edge of the workpiece of the CCD chip, and means for illuminating the edge region of the disc for viewing by the camera in silhouette, wherein the CCD array contains a large umber of addressable pixels in a rectangular array.
A machine for edge grinding circular workpieces, comprising workpiece holding means for attachment to the face of a workpiece to move the latter from one position to another, robotic means controlling the position of the workpiece holding means and adapted to move in at least two orthogonal directions, both of which are parallel to the plane of the workpiece when it occupies an optical inspection station, means for rotating the workpiece in the inspection station and in a machining station, inspection means for determining the position of the geometric centre of the workpiece as it is rotated in the first station, and computing means for calculating from data delivered by the inspection means any shifts required along the orthogonal directions of movement of the robotic means, to move the geometric centre of the workpiece to a second desired position whose coordinates are known, the optical inspection means comprising a CCD camera having its optical axis parallel to the axis of the workpiece and which forms an optical image of the edge of the workpiece on the CCD chip, and means for illuminating the edge region of the disc for viewing by the camera in silhouette, further comprising electric circuit means receptive of signals obtained by scanning the CCD array, adapted to convert the signal from each addressed pixel in the CCD array into a digital value according to whether a pixel is shaded by the image of the disc edge or not.
A machine foe edge grinding circular workpiece, comprising workpiece holding means for attachment to the face of a workpiece to move the latter from one position to another, robotic means controlling the position of the workpiece holding means and adapted to move in at least two orthogonal directions, both of which are parallel to the plane of the workpiece when it occupies and optical inspection station, means for rotating the workpiece in the inspection station and in a machining station, inspection means for determining the position of the geometric centre of the workpiece as it is rotated in the first station, and computing means for calculating from data delivered by the inspection means any shifts required along the orthogonal directions of movement of the robotic means, to move the geometric centre of the workpiece to a second desired position whose coordinates are known, the optical inspection means comprising a CCD camera having its optical axis parallel to the axis of the workpiece and which forms an optical image of the edge of the workpiece on the CCD chip, and means for illuminating the edge region of the disc for viewing by the camera in silhouette, wherein for a fixed number of pixels, the degree of digitisation of each pixel signal value determines the accuracy of the inspection system.
A machine for edge grinding circular workpieces, comprising workpieces holding means for attachment to the face of a workpiece to move the latter from one position to another, robotic means controlling the position of the workpiece holding means and adapted to move in at least two orthogonal directions, both of which are parallel to the plane of the workpiece when it occupies an optical inspection station, means for rotating the workpiece in the inspection station and in a machining station, inspection means for determining the position of the geometric centre of the workpiece as it is rotated in the first station, and computing means for calculating from data delivered by the inspection means any shifts required along the orthogonal directions of movement of the robotic means, to move the geometric centre of the workpiece to a second desired position whose coordinates are known, the optical inspection means comprising a CCD camera having its optical axis parallel to the axis of the workpiece and which forms and optical image of the edge of the workpiece on the CCD chip, and means for illuminating the edge region of the disc for viewing by the camera in silhouette, further comprising means for storing each frame in succession, means is provided by which it is possible to compare pixel dependent signals from one frame to the next, further means is provided to determine from that comparison any change in the value of the pixel dependent signal from one frame to the next, thereby to produce a signal indicative of any shift in the position of the image of the edge brought about by movement of the edge of the disc in the field of view due to eccentric mounting of the disc for rotation.
A machine for edge grinding circular workpieces, comprising workpiece holding means for attachment to the face of a workpiece to move the latter from one position to another, robotic means controlling the position of the workpiece holding means and adapted to move in at least two orthogonal directions, both of which are parallel to the plane of the workpiece when it occupies an optical inspection station, means for rotating the workpiece in the inspection station and in a machining station, inspection means for determining the position of the geometric centre of the workpiece as it is rotated in the first station, and computing means for calculating from data delivered by the inspection means any shifts required along the orthogonal directions of movement of the robotic means, to move the geometric centre of the workpiece to a second desired position whose coordinates are known, the optical inspection means comprising a CCD camera having its optical axis parallel to the axis of the workpiece and which forms and optical image of the edge of the workpiece on the CCD chip, and means for illuminating the edge region of the disc for viewing by the camera in silhouette, wherein as the disc is rotated, any misalignment between the geometric centre of the disc and its axis of rotation in the inspection station, will appear as a shift of the image of the disc on the CCD.
A machine for edge grinding circular workpieces, comprising workpiece holding means for attachment to the face of a workpiece to move the latter from one position to another, robotic means controlling the position of the workpiece holding means and adapted to move in at least two orthogonal directions, both of which are parallel to the plane of the workpiece when it occupies and optical inspection station, means for rotating the workpiece in the inspection station and in a machining station, inspection means for determining the position of the geometric centre of the workpiece as it is rotated in the first station, and computing means for calculation from data delivered by the inspection means any shifts required along the orthogonal directions of movement or the robotic means, to move the geometric centre of the workpiece to a second desired position whose coordinates are known, the optical inspection means comprising a CCD camera having its optical axis parallel to the axis of the workpiece and which forms and optical image of the edge of the workpiece on the CCD chip, and means for illuminating the edge region of the disc for viewing by the camera in silhouette, wherein a second camera is positioned so as to view the edge of the disc tangentially, with the optical axis of the camera in or parallel to the plane of the disc, to permit the profile of the edge of the disc to be inspected to and enlarged scale by displaying an enlarged image of the optical image presented to the camera in a CRT.
Dependencies are inferred from the claim text.