APPARATUS FOR DETERMINING MEASUREMENTS OF AN OBJECT UTILIZING NEGATIVE IMAGING

An apparatus for determining measurements of an object moving along a conveyor path having a support surface is provided. The apparatus includes an object detector located along the conveyor path which is adapted to detect the leading edge of the object and generate a leading edge signal. An object speed detector is located along the conveyor path and is adapted to generate an object speed signal. A light source is located above the conveyor path and generates a light beam having a sharp edge which extends across the support surface in a direction transverse to a direction of movement of the object to define a light beam intersect path on the support surface. The light beam is arranged at a fixed angle of incidence of less than 90° relative to the support surface. An image sensor is located above the support surface and includes a line of sight generally normal to the support surface which is directed through a lens located at a fixed position between the image sensor and the support surface to focus a reflected image of the light beam intersect path projected on the support surface onto the image sensor. The image sensor detects the light beam intersect path on the support surface only in areas not obstructed by the object and generates a negative image profile signal. A signal processor is provided in communication with the object detector, the object speed sensor and the image sensor which receives the leading edge signal, the object speed signal and the negative image profile signal and calculates an approximate object size. The object position and orientation can also be determined.