Long Distance Reflective Switch Provides Safe Operation In Industrial Machine Automation


Providing design engineers with a long distance sensing device for machine automation safety switches, TT electronics OPTEK Technology has developed a non-contact infrared switch capable of operation in industrial environments. Designated the OPB732 Series, the switch has a reflective distance exceeding three inches, depending on circuitry and reflective material.

According to Alan Bennett, vice president of sales and marketing for OPTEK Technology, the design of the reflective switch makes it ideal for machine automation applications. “The device features an opaque housing which reduces the sensor’s ambient light sensitivity, and is available with custom electrical, wire and cabling, and connectors, enabling machine design engineers to adapt it to their specific application,” explained Bennett. “In addition, the active optoelectronic components are protected by a clear window to enable the OPB732 Series devices to operate in dusty environments. These features make the switch ideal for applications involving door closures, end-of-travel indicators, short-distance safety curtains, and product positioning systems.”

While an object is in the path of the device, light from the LED will be reflected back to the housing, irradiating the surface of the phototransistor. When infrared light strikes the phototransistor, it becomes forward biased and is considered to be in the “on” state, providing an IC(ON) current proportional to the light striking the phototransistor. The phototransistor allows the designer to customize the switching threshold, providing an optimized solution for many applications. When the infrared light from the LED is not reflected to the phototransistor, the device turns “off,” minimizing the IC(ON) current.

The OPB732 Series infrared light emitting diode features an 850nm wavelength and a power dissipation of 100mW. Maximum forward current is 50mA and maximum forward voltage is 1.8V (If=20mA). Reverse DC voltage is 3V, with reverse current of 100?A (Vr=2.0V). Electrical performance of the output phototransistor is characterized at collector-emitter voltages of 30V, collector DC current of 50mA, and power dissipation of 100mW. Operating temperature range for the long distance reflective switch is -40C to +85C.

The OPB732 Series assembly is offered with either PC board through hole pins or 24”, 26 AWG RoHS wires. The phototransistor can be configured as a common collector or common emitter device.

Typical pricing for OPTEK’s OPB732 reflective switch is $2.97 each in quantities of 1,000. Lead time, if stock is not available, is from 8 to 10 weeks.


• Storage Temperature -40° C to +100° C • Lead Soldering Temperature (1/16” (1.6mm) from case for 5 seconds with soldering iron) • (2)- 260° C • Operating Temperature -40° C to +85° C • Forward Current 50 mA • Power Dissipation 100 mW • Reverse DC Voltage 3 V • Peak Forward current (2 µs pulse width, 0.1% Duty Cycle) 1 A • Collector-Emitter Voltage 30 V • Collector DC Current 50 mA • Power Dissipation 100 mW
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