Contrast sensors

Contrast sensors detect and compare contrasts very precisely through the use of different light sources such as white light, laser-generated red light or RGB light. The detected contrasts marks are then reported to the process with minimal signal jitter. Through the automatic selection of the right transmitter colors, various color or gray value combinations can be reliably detected. Bar graph indicators offer additional ease in making adjustments during manual setup.

KRT 3C contrast sensor: Our smallest contrast sensor for the packaging industry
New contrast sensor for fast and reliable identification of contrast differences in situations with limited installation space
Contrast sensors are developed to detect defined markings on objects during packaging processes. These contrast markers are located on film, bag and blister packaging or on labels. The new compact contrast sensor of the 3C series can be used flexibly with different transmitter colors (RGB light, white light or laser-generated red light) for all common color and gray value combinations. It reliably and precisely detects even slight contrast differences, as well as print marks even on glossy materials.

The sensor is developed for tight installation spaces: With a very compact housing (11 x 32 x 17 mm), it is our smallest contrast sensor and offers a high level of mounting flexibility. The robust plastic housing covers degrees of protection IP67 and IP69K. ECOLAB certification confirms the housing's resistance against cleaning agents commonly used in the packaging industry. All settings for integration and operation of the sensors as well as for the case of format changes of the products can be easily performed via the IO-Link interface.

Advantages for you
  • Flexible thanks to multiple types of light in a single housing: multicolor (red, green or blue light), white light and laser-generated red light
  • Reliable detection of even the slightest contrast differences and of print marks even on glossy and highly reflective materials
  • Highly precise and reliable identification of contrasts with a short response time of 50 µs (laser: 125 µs) and minimal signal jitter for optimum machine throughput
  • High mounting flexibility and easy integration even in tight installation spaces due to a compact and robust housing with a high degree of protection of IP 67 and IP 69K as well as ECOLAB certification
  • Multiple teach modes are available for selection, thereby ensuring the appropriate adjustment routine for easy and fast machine commissioning (static or dynamic 2-point teach, static 1-point teach)
  • IO-Link for easy integration of additional functions into the machine control, for example easy format changeover due to recipe management, parameterization of the sensor, or locking of the teach button to prevent tampering

Three light types in a compact housing
Every application has different requirements on the sensor system with respect to reliable contrast marker detection. Because the emitted light color determines the reliability with which contrast markers are detected, the new KRT 3C contrast sensors use three different light types. This allows customers to select the appropriate light source for each type of material and for each contrast marker color in packaging or labeling processes.

  • Multicolor uses red, green or blue LED light (RGB). Through the automatic selection of the right transmitter color, various color or gray value combinations can be reliably detected. Multicolor devices are especially well suited for very colorfully printed films.
  • The white light LED is used if it is necessary to distinguish colors and gray values from a reference gray value (with equal contrast resolution). This provides greater reliability particularly in the case of contrast markers on glossy surfaces.
  • Contrast sensors with a red light laser emit a very small laser light spot and are therefore the ideal choice for detecting very small markers and changes in distance.

Easy configuration and recipe management due to IO-Link
The new KRT 3C contrast sensors are adjusted either via a teach button, remotely by teaching via a cable or – conveniently – via IO-Link. Using IO-Link, sensors can easily be integrated in an automation system. This type of automation simplifies integration and thereby helps keep downtime in production to an absolute minimum. The new compact contrast sensors can be configured, operated and maintained (condition monitoring) via IO-Link.
  • Convenient format changeover to a different film or label type by uploading the respective parameter set including teach value to the contrast sensor (also possible directly via the Human Machine Interface (HMI))
  • No setup time and no re-teaching of the contrast sensor when changing format
  • Real-time signal information and diagnosis
  • Quick and easy remote teaching or locking of the teach button via IO-Link interface
  • The variety of teach modes enables fast commissioning of the machine:Static 2-point teach: Suitable for manually positioning markers and background
  • Dynamic 2-point teach: Suitable for moving markers within automated machine processes
  • Static 1-point teach: Suitable for detecting any type of markers against a homogeneous background or outside of a reference value

The requirements placed on sensor systems are high in packaging processes: Objects or cut marks must be detected quickly and with high switching reliability. In addition, there are also challenging environmental conditions such as tight installation spaces or frequent cleaning processes. The new KRT 3C contrast sensors have a robust miniature housing and can be used flexibly for various detection tasks.
  • The small construction, just 32 mm in height, ensures flexibility during mounting, especially in confined spaces
  • This product can also be used in areas requiring degrees of protection IP 67 and IP 69K
  • The ECOLAB certification ensures that the sensors are also suitable for applications where the system is cleaned regularly and cleaning agents are used

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