Vision sensors provide critical measurements in many industrial applications for counting, sorting, pattern recognition, positioning and other quality control aspects. However, the limitations of monochromatic sensors have driven several suppliers to design color sensors. Sometimes, a programmable color sensor is sufficient to detect subtle differences. Applications requiring color discrimination similar to the human eye have special design considerations, since a traditional red-green-blue (RGB) sensor sees color differently which limits its ability. In all cases, a simple and straightforward means to teach the sensor to know the difference between an acceptable or rejected unit is essential.
SMART VISION SENSING
With the ability to distinguish shapes and colors, Omron's ZFV-C offers sensing capabilities close to human vision. The image processing system implements integrated color filters to sense selected colors for a better image. The unit's “Teach and Go” function uses a color LCD screen and simple menu to reduce the setup steps for inspections. The display provides a real-time image for feedback during both setup and inspection operations. Depending on the controller, available sensor functions include counting, pattern recognition, size verification, position, brightness, width, text verification and hue (comparing sensed color to a reference color). One controller bus can handle up to five sensors through a snap-on system, allowing five different inspections in a single pass for increased productivity. The sensor targets industrial applications that require a quick, easy setup to sense color variations in manufacturing, assembly and packaging lines. Get more information on Omron Electronics ZFV-C Smart Sensor.
SENSING COLORS INDEPENDENTLY
A single Pepperl+Fuchs Dura-Vue DF12 series color sensor can recognize three independent colors. The sensor's three channels are taught the appropriate colors and allowable tolerances through potentiometers or an external teach input from a Programmable Logic Controller (PLC). The selected color tolerances determine color shade accuracy with the maximum relative sensitivity for all three colors occuring at a distance of 10 mm from the target. Based on the connected load, each output automatically sinks or sources current. The unit has versatile lens mounting and comes in a rugged die-cast metal housing with a swivel connector. The sensor targets sorting, positioning, and quality control in packaging and converting applications. Get more information on Pepperl+Fuchs' Dura-Vue DF12 color photoelectric sensors.
COLOR PERCEPTION SENSOR
To sense colors and color variations similar to the human eye, Silicann Technologies' GmbH PCS-II implements the International Commission on Illumination (CIE) 1931 Standard Colorimetric System response curve for human vision. Designed for high-speed industrial control and measurement applications with data rates up to the kHz range, the PCS-II sensor provides fast color recognition for up to 255 user-defined colors. A 1-W white LED with adjustable brightness provides the illumination for operational modes that include color control, color recognition, color classification, and color measurement. Based on a sampled reference color, accuracy is better than DE=0.5 with the color resolution DE(Lab) less than 1. The unit's integrated photodetector uses filter curves that correspond to visual responses. The sensor's controller processes internal RGB signals to achieve spectral sensitivity similar to human color perception. Target applications for the PCS-II include color sensing for: (1) emitted light from LEDs, LCD and other displays, and monitors, and (2) reflected light from paint, print, textiles and plastics. Get more information on Silicann Technologies PCS-II perceptive color sensor.