Non-Contact Infrared Switch Provides Object Sensing At Ranges Up to 24”


Providing design engineers with a device capable of operating in contaminated environments, TT electronics OPTEK Technology has developed a long distance reflective switch with a sensing distance of up to 24” or more, depending on the object. Designated the OPB725 Series, the reflective switch consists of an infrared LED and Photologic® sensor in an opaque housing to reduce the sensors ambient light sensitivity.

According to Roland Chapa, vice president of OPTEK Technology’s assemblies business unit, the components of the switch allow it to be used in a variety of applications. “The emitter and sensor are protected by a window that is transparent to near-infrared wavelengths, which allows it to operate in dusty environments,” said Chapa. “Additionally, the Photologic sensor has an NPN open-collector output, making the switch suitable for use in a variety of applications.”

Applications for the reflective switch include non-contact reflective object sensing, assembly line and machine automation, equipment security, door and end-of-travel sensing, and machine safety.

While an object is in the reflective path of a device, light from the LED will be reflected back to the housing, irradiating the surface of the Photologic® sensor. This causes the output NPN transistor to turn “on,” providing a “low” output voltage when connected to the appropriate value pull-up resistor, Chapa continued. When the infrared light from the LED is not reflected to the Photologic sensor, the output transistor turns “off,” minimizing the IC(ON) current and providing a “high” output.

The OPB725 Series long distance reflective switch features an 850nm LED, and the assembly is offered with 48” (122cm) AWG wires. The device features a power dissipation of 250mW, a maximum collector voltage of 30V, and a collector DC current of 50mA. Operating temperature range is 0°C to +50°C.

Pricing for the OPB725 Series reflective switch starts $14.95 each in quantities of 5K. Lead time, if stock is not available, is from 6 to 8 weeks.
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