Relays, The Electromechanical amplifier

Pyroelectric Infrared Sensor and Fresnel lens

DPB PYD1798 Digital Motion Detector components

DP-001 Digital Motion Detector Module

DP-002 Digital Motion Detector Module

How IR motion detector components work

Focusing devices for pyroelectric sensors

RIR Reflective Infrared devices 





RIR Reflective Infrared presence/proximity/motion detector with self programming detection range.


Unlike a Pyroelectric Infrared sensor (PIR) that is used in many motion detectors, the Reflective Infrared sensor (RIR) does not detect long wavelength infrared radiation emitted by a human or animal body. Instead, a device using an RIR sensor emits its own short wavelength infrared beam and the RIR detects the infrared that is reflected back to it from any human or non-human object within its automatically programmable detection zone. It can continuously detect the presence of both a moving and stationary object.


Short wavelength infrared used by the RIR will pass through most materials that are transparent to visible light. It reflects from both light and dark surfaces but reflection is stronger from light and smooth surfaces. Dark surfaces and textured surfaces that scatter light will result in less reflected light which the sensor within the RIR circuit will interpret as reflections from a more distant object. A reflective infrared system will therefore not produce an accurate measure of distance from the sensor to a detected object.


However, the purpose of the RIR is not to measure distance but to detect a stationary object, to detect motion toward and away from the sensor and to automatically control its detection distance with some variations as described above, none of which a pyroelectric infrared sensor can do. Table 1 shows a comparison between a pyroelectric and reflective infrared sensor system.




Pyroelectric Infrared Sensor (PIR)

Reflective Infrared Sensor (RIR)

Sensor type Passive Active

Infrared wavelength

5 to 15 micrometers

940 nanometers

Detects IR from animal body

Yes- senses IR emission

No- needs LED IR source

IR will pass through glass, plastics



Detects metal objects

No- sometimes but not reliable

Yes- detects reflection

Very long detection range

Yes- More than 100 feet

No- Up to 20 feet

Can detect stationary object

No- Only moving

Yes- Stationary and moving

Detects movement side to side



Detects movement toward and away



Wide field of view

Yes- Depends on lens used

No- only narrow

Controllable detection distance

No- Background sensitive

Yes- Automatic programming

False activation by rain, snow



External lens required

Yes- Needs a Fresnel lens

No- Lens built into sensor

Can be powered by small battery

Yes- About 50 microamps

No- About 200 milliamps


Table 1


In one configuration, when power is applied the RIR will look at all objects within its field of view and will program its self to consider them as normal occupants of its detection zone. However, when a new object enters its zone it will immediately recognize that object as an intruder and will respond by turning its output on. The output will remain on until the intruder leaves the detection zone.


The RIR is especially useful to detect a stationary person or object. A typical application is to activate illumination of a picture or display in a gallery when a person approaches the display and then stands still in front of it. The RIR can easily be programmed to activate when a person is within a desired distance from the display by simply sequencing power or pressing a reset button while a person stands in front of the display. The RIR will measure and save the distance to the person as an activation zone and will thereafter activate the illumination whenever anyone enters a short distance inside that zone.

We will provide more information about this new device as it becomes available.




Copyright 2015
Glolab Corporation