Sensors offer more stable, reliable colour recognition
03 November 2011
Micro-Epsilon has introduced a new range of colour recognition sensors that provide up to 20 times higher resolution than conventional colour recognition sensors and offer more stable, reliable colour measurements, even on shiny or reflective surfaces. The sensors are also able to recognise small variations in colour along a target object or material, for example, in the production of leather goods, wood veneers and vehicle interiors.
True colour recognition is required in many industry sectors, enabling companies to select, monitor, grade and sort various types of coloured objects involved in manufacturing, automated handling, warehousing, packaging, wrapping and other production processes. Measured objects can take the form of solids or liquids and the user may also have a need to recognise the colours of transparent surfaces such as coatings or labels, as well as LEDs or lamps.
With its new colorSENSOR series, Micro-Epsilon is now able to offer customers in the UK one of the widest ranges of colour recognition sensors in the world – available from a single source. This range includes the colorSENSOR LT, sensors that operate using optical fibres. Here, the sensor is connected to an optical fibre that is guided to the measurement target.
Colour detection therefore takes place very close to the object, which reduces any environmental effects that could adversely affect the reliability of measurements. More than 2,000 different types of fibre optic cable are available to choose from, as well as a large number of lenses. These provide customers with an almost unlimited number of combinations of sensor and optical fibre, which in turn enables Micro-Epsilon to help customers select the most optimum colour recognition sensor for their application.
The colorSENSOR LT range includes low cost, entry-level sensors through to high precision, multi-channel colour recognition systems. The LT range offers measuring distances from 2-100mm and up to 255 colour memory locations. As well as exact colour, these memory options enable the user to store specific tolerance limits for different applications.
During colour recognition inspection, the sensor compares the colour it has been taught with the colour currently detected. The results are then made available via digital interfaces (RS232 or USB) as discrete values/numbers or NO/NOK statements. The sensors are supplied with their own set up and configuration software and a graphical user interface that enables the user to adjust the sensor to suit different applications.
Using new LED light sources, LT sensors can now be mounted much further away from the measurement target if required, at distances of up to 2,000mm.
Micro-Epsilon’s colorSENSOR OT series of colour recognition sensors operates by using fixed optical systems. These sensors are able to recognise the colour of objects from longer distances (from 2mm to 800mm). Different models are available to suit different surfaces and materials, including shiny, reflective and structured surfaces, as well as versions for recognising UV markings. OT sensors can even recognise colour variations along or between target objects and materials. This is particularly beneficial to manufacturers of vehicle interiors, leather, embossed film, fabrics, wood veneers and large painted components, where the smallest colour variation is deemed unacceptable by the customer.
OT sensors use eight white-light LEDs, whose brightness can be controlled as required. These LEDs are used as light sources for diffuse illumination. The switching status is displayed using five yellow LEDs. The sensors are insensitive to external light and have a true colour detector that filters RBG values in a similar way to the human eye. However, a ‘best hit’ mode uses vector formation to show colours that are so similar that they are almost indistinguishable to the human eye. This provides customers with unambiguous, process-safe colour differentiation.
Adaptive learning
All sensors in Micro-Epsilon’s colorSENSOR range benefit from a ‘teach-in’ function. This enables the sensor to learn and adapt to the application by using samples of the correct colour. Following this process, the sensor is able to compare the colour samples it has been taught with the target object, then operating independently.
Micro-Epsilon’s colorSENSORs are available for a variety of tasks including the differentiation and grading of coloured objects and materials such as bottles, liquids, labels, packaging, bottle caps and cables. Other sensors in the colorSENSOR series enable the position monitoring of objects such as pallets, tiles, textiles, granulates, pills, soldering points, food products, liquids and so on. Colour recognition sensors are also available for observation tasks, including the degree of ripeness of fruit, coated foods, varnish and coloured liquids.
Outside of the UK, the colorSENSOR series has already found applications in numerous industry sectors, including automotive (vehicle interiors and paintwork), machine building & automation, electricals, chemicals, pharmaceuticals, cosmetics, medical, food and beverage processing, agriculture, security, paper, printing and packaging.
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