Sophisticated new material handling systems require sensors with onboard intelligence. Advancing semiconductor technology has allowed microcomputers to become an integral part of photoelectric and ultrasonic sensors. Overall, these devices significantly increase the efficiency of palletizers, conveyors, packaging machines, and other material handlers.
The most realized benefits of smart sensors with onboard intelligence include more reliable sensing of difficult to detect objects or materials, elimination of background interference, the ability to adjust the sensing field to the range of the target object, and the ability to precisely gauge the distance of the target from the sensor.New sensor technology includes patented "teachable" sensors that can "learn" to detect objects that were previously impossible to sense. These single pushbutton sensors utilize an advanced microprocessor that differentiates between 2 received light levels for the most precise sensitivity adjustment. Point-and-push teaching is accomplished by pushing the button once with the sensor pointed at the target, and once with it pointed at the background. The sensor's microprocessor recognizes low-contrast conditions and expands the sensitivity range before computing the optimal setting for differentiating between the received light signals.
These sensors can reliably handle such tough applications as colormark detection on a continuous web, and sensing clear bottles or wafer cassettes on a moving conveyor line. For maximum efficiency and convenience, they can be programmed from an external switch or PLC. Sensing modes include regular and wide-angle diffuse (proximity), polarized retroreflective, convergent beam, plus glass and plastic fiber optic models.Smart diagnostics include a green LED indicator that provides an accurate display of sensing contrast, so the operator knows application stability at a glance.
New fixed-field photoelectric sensors solve the problem of background interference behind the conveyor by using optical triangulation to sense a target, rather than relying on reflective surface brightness for a signal return path. These powerful and precise fixed-field devices, with ranges to 79 in., can sense flat black objects at exact distances while ignoring highly reflective backgrounds only inches beyond the cutoff point.Fixed-field technology offers extremely high gain for maintenance-free operation and the capability to detect both dark and light objects. High-gain circuitry allows even black plastic or recycled wooden pallets to be detected. These sensors are vastly more reliable than similar units that require a mechanical range adjustment that can be thrown off by machine vibration.New ultrasonic sensor technology allows extremely accurate gauging of distances to resolve object presence within hundredths of a millimeter. Pushbutton programming enables users to set their own custom sensing "windows," as compared with inflexible competitive fixed-range units.
