object detecting sensors adjust their detection threshold depending on the amount of ambient light and optical noise present in the environment. To avoid false detections in the presence of noise, the gain of the amplifier may adjust itself to such a low level that sensor responsiveness is affected. In low ambient light conditions, the sensor may increase its gain and make the receiver too sensitive, such that it will detect and respond to reflected or stray light.
The TSOP4038, TSOP58038, and TSOP5038 IR sensors with digital output eliminate these problems by featuring a fixed gain. With a fixed gain the detection threshold and resulting detection distance is fixed. Once the design of the optical parameters such as the intensity of the emitter, the aperture in front of the receiver, and the alignment of emitter and detector are determined, the sensor will have stable, repeatable performance under all lighting conditions.
Many other applications require a reflective sensor that detects not only presence but also proximity by measuring the strength or weakness of the reflected signal. Instead of a fixed detection threshold, analog information from the sensor is needed. This is possible with the TSOP4P38, TSOP5P38, and TSOP58P38 IR proximity sensors. The length of the sensor's output pulse in response to the emitter signal varies in proportion to the amount of light reflected from the object being detected. For near objects, the output pulse approaches 100 % of the emitted pulse; for far objects, the output pulse becomes shorter.
Vishay's mid-range sensors enable a wide variety of safety mechanisms and automatic fixtures in homes, businesses, and industrial settings. Typical applications include safety switches for garage doors, elevator doors, gates, perimeter guards and industrial light curtains, and reflective sensors for toilets, urinals, faucets, hand dryers, towel dispensers, and LCD monitor power sensors.
In applications such as light curtains and perimeter guards, fast reaction times are critical. While some sensors require the IR beam to be interrupted for up to 5 ms before detection, Vishay's mid-range sensors require only 300 μs.
The new IR sensors provide shielding against EMI and a supply voltage of 2.7 V to 5.5 V. To simplify designs, the devices feature a photo detector and preamplifier in one package, while visible light is suppressed by an internal IR filter. The components are compliant to RoHS 2002/95/EC and WEEE 2002/96/EC.