Colour sensors and contrast sensors
Photoelectric colour & contrast sensors detect colours and grey levels through use of multicoloured light. The desired colour or grey level is progr. at touch of a button on the sensor. Device adjusts automatically to ensure optimum recognised of desired colour/ grey level Particularly suitable for fast counting & sorting tasks. Read more here
Colour sensors and contrast sensors
All items of the category Colour sensors and contrast sensors:
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Colour sensors & contrast sensors: precise detection for your automation
Colour and contrast sensors detect colour values and brightness differences on surfaces and use them to generate switching signals for downstream sorting, inspection and positioning tasks. Colour sensors work with RGB colour evaluation and distinguish between several colour values within a spectrum defined via teach-in. Find the right sensor for your application here - as always at autosen, at the best price and available from stock for immediate delivery.
The most important question first: colour sensor or contrast sensor?
Not sure which technology is right for you? Here is a direct comparison:
| Sensor type | Task | Advantages | Disadvantages |
|---|---|---|---|
| Colour sensors | Detect, inspect or sort objects based on their specific colour (e.g. "is the component red or blue?") |
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| Contrast sensors | Detect brightness differences or print marks on surfaces (e.g. "is the black mark on the carton here?") |
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Colour sensors: when exact colour makes the difference!
Our colour sensors use RGB light to inspect the exact colour of an object and compare it with a taught reference value. The sensor calculates the colour value components from the reflection and compares them with the taught reference colour values. If the measured values correspond to the reference, the sensor switches. This enables sorting and detecting objects by colour as well as presence checks. Important in practice: for maximum repeat accuracy, stray light influences should be minimised and a constant mounting distance ensured.
Find out more about our colour sensor: Colour sensor 15...19 mm for detection, sorting & inspection.
Contrast sensors: when speed and precision matter!
Contrast sensors, on the other hand, are specialists in detecting print marks and the slightest contrast differences. Their strength lies in fast, cyclic processes where they respond precisely to print marks or edges. Many models optimise the contrast automatically by selecting the appropriate light colour (red, green or blue).
The sensor is taught to the desired surface and reliably detects contrast differences. Their high switching frequency makes them the first choice for printing and packaging machines with high output volumes.
Typical applications of colour and contrast sensors
Typical applications of colour sensors:
Quality control: inspect coloured caps, labels or components.
Sorting tasks: separate objects by colour (e.g. in the recycling or food industry).
Presence checking: ensure that the correct coloured part is present.
Typical applications of contrast sensors:
Print mark detection: precise positioning of labels, films and packaging.
Object detection on conveyor belts: distinguish between light and dark objects.
Process control: counting objects with printed markings.
Frequently asked question about colour and contrast sensors
Colour sensors identify the colour itself (e.g. "Is this red?"). Contrast sensors identify a difference in brightness (e.g. "Is there a dark line here on a light background?").
Select an optimum distance from the object and make sure that the lighting conditions are constant. Carry out the teach-in process on the desired colour and save the values.
With highly glossy surfaces, adjusting the angle of incidence often helps. For transparent materials, there are special sensors or targeted back reflection (e.g. by a reflector behind the object) can help. In these cases, models AO704 and AO701 are a suitable recommendation.
Simple and flexible: depending on the model, our sensors offer standard switching outputs (PNP/NPN), analogue signals or an IO-Link interface for direct communication with your PLC.
The colour and contrast sensors are very robust. Regular cleaning of the optics and occasional checking of the taught values are sufficient to guarantee permanently high process reliability.
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