Contrinex unique UV Transparent-object Detection Photoelectric🔦 sensors give ‘Blistering’ performance on clear🔍 blister packaging

Automated packaging increasingly uses transparent thermoformed plastic tray bases and Contrinex’s transparent-object sensors with patented UV technology are ideal at detecting the presence of each set of transparent trays after it is formed. The sensor reliably detects the presence of each transparent tray after it is formed because it is unique in using polarised ultraviolet light at 275nm, which is absorbed by the plastics used in thermoforming, even if they are thin and transparent. The Ecolab-certification of these sensors makes them suitable for the packaging of food and medical products.


A manufacturer of packaging machines for the medical industry produces automated blister-packaging lines for pharmaceutical and surgical products. Medical blister-packs comprise a recessed, semi-rigid tray base, vacuum-formed in-line from clear thermoplastic material and sealed with a metal or plastic film after the desired products are loaded.

Typically, blister-packaging lines for surgical products operate in sterile conditions; minimal manual intervention is permitted, as contamination may enter the environment. If defective bases are identified and rejected after forming, the flow of tray bases to the loading station is not continuous. In this event, a sensor system must inhibit the loading cycle until a base is in position.

Sensors must detect the presence of transparent tray bases swiftly and reliably, enabling the loading cycle to proceed with minimal delay as soon as a tray is present at the loading station. Standard photoelectric sensors, which use visible red-light sources, proved unreliable as they are unable to differentiate reliably between ‘tray present’ and ‘tray not present’ conditions. Contrinex’s transparent-object sensors with UV technology offer an alternative sensor technology which will reliably detect the presence of a transparent plastic target.


Transparent-object sensors with ultraviolet LED-light sources from the Contrinex C23 product series are ideally suited to this application. These miniature cubic devices, mounted above product conveyors, detect the presence of transparent tray bases as they arrive at the loading station. Positioning sensors is simple thanks to a range of adjustable mounting brackets, and auto-collimated optics ensure there are no blind zones.

Contrinex transparent-object sensors utilize a patented reflex operating principle with polarized ultraviolet light at 275 nm. At this wavelength, absorption of the polarized UV light by a range of commonly used plastics is maximized. Custom-designed UV reflectors, using high-tech plastic materials with excellent reflective properties in the ultraviolet range, provide a range of sizes and geometries that simplify installation.

An industry-standard PNP normally-open output ensures optimum flexibility. Additionally, IO-Link, a standardized point-to-point serial connection protocol for sensors and actuators, is enabled on PNP versions at no additional cost. An additional option is to have a second output to provide the stability alarm in the event of reduced sensitivity, flagging the need for preventative maintenance before any performance degradation occurs.

The robust sensors which are only 20mm x 30mm x 10mm feature Ecolab-certified plastic housings. A sensing range up to 1200 mm, adjustable via a teach button or via IO-Link, accommodates a wide range of machine geometries.

Sensitivity parameters are stored on the sensor’s inbuilt memory and may be retrieved or updated remotely via IO-Link, eliminating the need for manual adjustment.

The robust sensors which are only 20mm x 30mm x 10mm feature Ecolab-certified plastic housings, are corrosion-resistant and impervious to water ingress and has the additional benefit of offering a range of low-cost stainless-steel mounting and protection bracketry.

PLUS Automation aims to help you #MAKESENSEOFSENSORS, helping solve applications, improve machine performance and reliability, and reduce costs using Contrinex’s exceptional choice of Inductive🧲, Photoelectric🔦, Ultrasonic🦇, RFID📻 & Machine Safety👷 sensors. Find more information and read other application examples go to


🕵🏽‍Reliable & fast detection of the thinnest materials

📈Maximum operating reserve due to the high-absorption of UV light by transparent plastics

✨Elimination of multiple switching on a single-target = steady signal

🔧Reliable operation without adjustment

💦Very low sensitivity to dust, liquid droplets and splashes

🧠Pre-taught sensitivity parameters stored on inbuilt memory

💪Robust & affordable mounts and shields available

🎛️IO-Link – Ideal for Industry 4

🔢Remote sensitivity retrieval or update over IO-Link


Click to find out more about these sensors, or Click to download Contrinex’s Product Overview brochure

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