Radiant energy – Photocells; circuits and apparatus – With circuit for evaluating a web – strand – strip – or sheet
Reexamination Certificate
2000-08-02
2002-05-21
Le, Que T. (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
With circuit for evaluating a web, strand, strip, or sheet
C250S559360
Reexamination Certificate
active
06392247
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to a sensor and detection system for detecting the presence or position of surfaces, and more particularly to a sensor and detection system having wide diverging beam optics for increasing the angle of detection coverage.
BACKGROUND OF THE INVENTION
Sensors are used for a variety of purposes. One useful purpose is as an detection system for detecting the presence of objects. In particular it has been found to be difficult to detect the edge of objects, or objects with small, specular surfaces. A sensor and detection system and method which solves this problem is taught in U.S. Pat. No. 5,504,345, which is owned by assignee, and is herein incorporated by reference. The '345 patent discloses a semiconductor wafer and magnetic disk edge detection system having converging dual-beam optical sensor. The sensor comprises at least two light sources, and at least two light detectors. The light sources, or the light beams emanating form the sources, are spatially oriented such that the focal point of the converging light beams define a focal or inspection plane and converge at a single point external to the sensor. When the object interrupts the beam at or near the focal point of the light sources, it causes the light to be reflected backwards toward the sensor by the light detectors. The light detectors are spatially arranged so they can receive the light reflected.
The '345 patent teaches a very useful device, however it would be useful to increase the angle of coverage of the sensor. When the light strikes the object and is reflected backwards there is a certain angle associated with the return path of the reflected light. It is possible for light to be reflected in a vicinity remote from the light detectors. This results in a “blind spot” where the light is not detected. Thus, it is desirable to provide a sensor and detection system that exhibits improved coverage and substantially eliminates blind spots.
OBJECTS AND SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a sensor and detection system with improved angle of coverage.
More specifically, it is an object of the present invention to provide a sensor and detection system having wide diverging beam optics.
Another object of the present invention is to provide a sensor and detection system capable of detecting the edge of objects, particularly objects having small, specular or reflective surfaces.
Still another object of the present invention is to provide a sensor and detection system capable of detecting the edge of an object where the edge is at an angle of incidence that deviates significantly from the position which would generate ideal reflection to the receiver.
These and other objects, features and advantages of the invention are achieved by the sensor and detection system of the present invention, comprising at least one transmitter having associated optical elements for emitting at least one light beam toward the object to be detected. At least one receiver is positioned adjacent the transmitter for receiving light reflected from an edge of said object when said object intersects the one light beam. The receiver generates a signal responsive to the reflected light. The associated optical elements of the transmitter include a converging lens for emitting a focused light beam in one plane, and a cylindrical lens for emitting a diverging light beam in a perpendicular plane, such that a portion of the reflected light is diverging and is received by the receiver over a wide angle of coverage:
In an alternative embodiment of the present invention, a detection system is provided which comprises the sensor as described above, and includes means for causing relative movement between the object and the at least one transmitter, and a position encoder for providing proximity and location data responsive to the signal, thereby detecting the object.
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Bartunek Hans
Cerny Mark
Dicke, Billig & Czaja P.A.
Hama Sensors, Inc.
Le Que T.
Luu Thanh X.
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