Fields of application for our color sensors

The following examples illustrate the wide spectrum of applications already implemented with our color sensors:

  • Detection of fuel by color (transmitted-light method)
  • Color sorting of plastics granules, hygiene products, tablets, ...
  • Color sorting and assignment of crayons, lipstick, rouge, eyeshadow ...
  • Color inspection of coatings, cosmetics bottles, packaging ...
  • Detection of colors and color markings on packaging
  • Detection of color changes in a liquid (e.g. blue to red)
  • Detection of the degree of browning of baked goods
  • Detection of the customs banderole on cigarette packs
  • Detection of caps on medication cans
  • Detection of color codes on infusion packaging
  • Inspection of color and intensity of LEDs and signal lights
  • Testing of lamps and LEDs inside switches
  • Checking the color of plug connections
  • Material detection of electrical contacts in relais, contactors, jacks (from gold, silver, copper, tin etc.)
  • Corrosion detection, polarity detection, pollution detection
  • Glue detection, tinning detection and solder detection
  • packaging inspection
  • Color sorting tasks (e.g. weldseam tracking, o-ring inspection, closures, bottle caps, labels, ...)
  • Color detection on injection-molded parts
  • Inspection of glue application on nuts and bolts
  • Color marking detection on bearing shells
  • Detection of plastics rings on wooden screws
  • Color detection of body shell parts, spings, bumper bars, wheel covers, doors, interior panelling
  • Color codes on gearbox parts, engine parts, motors
  • Sorting and inspection of colored plastics and wood bricks
  • Sorting and inspection of colored playing pieces
  • Sorting and inspection of all kinds of colored toy parts

Color sensor application reports

Detection of a foil in long-time operation

Task for the color sensor:

A machine manufacturer for PCB processing has the challengo to detect red foils in a long-term stable way. Color sensors in greater quantities will be used. The sensors should be fully functional without configuration efforts, immediately after installing. This calls for an option to transmit sensor parameters without individual adjustment on the machine.

Used products:

Compact color sensor PCS-I, electronically balanced

Solution:

The task could be solved with PCS-I color sensors. Prior to shipping the sensor gets calibrated exactly for color the customer asked for. All parameters can then be transmitted from one sensor to another without any individual onsite configuration.

Detection of a barely visible yellow discoloration of polyethylene glycol

Task for the color sensor:

Polyethylene glycol in perfect condition is a clear, transparent liquid. Thermal stress or suboptimal lighting can cause a slight yellow discoloration that has to be detected before further use. The liquid has to be inspected inside a 55mm tube.

Used products:

  • Compact color sensor PCS-I-F
  • Transmitted-light optical fibers with M6 probes and 2.5mm fiber bundle diameter

Solution:

The task could be solved with a combination of a PCS-I-F color sensor and transmitted-light optical fibers with M6 probes. For this application the fibers work according to the light barrier principle, the M6 probes got screwed directly into the tube. The LAB color value for clear polyethylene glycol was saved as the reference value directly into the sensor. Tolerance threshold has been set to 1. This configuration reliably detected the discolorations.

Checking for presence of ball bearing covers

Task for the color sensor:

Ball bearing manufacturers are covering the bearing cages with metal covers. Presence of the covers has to be checked using color sensors. The color values of the covers partially overlap with those of balls, cage and bearing wall, and all parts are glossy, renderung measurements non-trivial.

Used products:

Color sensor PCS-II, reflected-light fibers with cross section converter (6x1)mm

Solution:

The task could be solved with a combination of a PCS-II color sensor and reflected-light fiber optics with a cross section converter. The converter created line-shaped measuring spots. This way, averages of the color impressions of a 6mm section of the ball bearings could be measured, resulting in distinct color values for ball bearings with and without covers in place.

Detecting the base color for 6 different plastics caps for pharmaceutical vials

Task for the color sensor:

Pharmaceutical vials are covered with differently colored pastics caps and sorted using a sorting machine. Color differences from batch to batch are clearly visible for the caps. Color detection shall assign each cap to one of six base colors. The caps have a slim area of 2mm width that shall be used for color detection. The sorting machine works using six lines working in parallel. Cap color detection has to occur synchronously.

Used products:

6 x color sensor PCS-II, 6 x reflected-light optical fibers, 6 x focus optics KL-3

Solution:

The task could be solved using six sets of PCS-II color sensors, reflected-light optical fibers and focus optics KL-3. Each color sensor has been trained with the 6 base color values and a tolerance value reflecting the inter-batch variance of the cap colors has been configured. For synchronization the witched outputs of the color sensors were used.

Orientation detection for silicone sealing washers with one-sided PTFE coating

Task for the color sensor:

Silicone sealing washers with one-sided PTFE coating pass an oscillating conveyor. Before further processing of the washers their position has to be checked. The coating produces a slight color difference between upper side and lower side of the washer.

Used products:

Color sensor PCS-II, reflected-light optical fibers with M6 probe

Solution:

The task could be solved with a PCS-II color sensor and reflected-light optical fibers. The optical fiber probe has been positioned with 2mm distance and an inclination of 45° to the washer surface. The color distance between upper side and lower side has been measured as delta E = 10. After training the color impression of the upper side and setting a tolerance of delta E = 6 both sides could be reliably differentiated at production speeds.

Detecting whether a silicone coating has been applied

Task for the color sensor:

Application of a thin silicone coating on parts is usually controlled by measuring the flow rate at the spray nozzle. With very light spraying intensities the sensitivity of the flow rate sensor is too low. In these cases checking for application by flow rate doesn't work. Visual inspection of silicone slip agent application is non-trivial because the slip agent is transparent.

Used products:

  • color sensor PCS-II
  • reflected-light optical fibers

Solution:

Color impressions of parts with and without applied silicone agent have been trained. The sensitivity of a PCS-II color sensor is then high enough to reliably detect the color difference even with thin coatings. The detection signal has then been sent to the machine using the switching outputs of the sensor.

Testing of LEDs in electronic assembly production

Task for the color sensor:

When mounting LEDs in electronic assembly production, uniform color and brightness quality has to be ensured. Testing the LEDs for correct color and brightness is necessary.

Used products:

  • Color sensor PCS-II in active mode
  • fiber optics

Solution:

The acceptable tolerances are preselected through parametrization of L value (intensity) and u'v' value (hue). By using the PCS-II software package the tolerances can be displayed visually on a computer. Automatic testing of produced components could be implemented reliably.

Detection of color markings in varying colors on bearing shells

Task for the color sensor:

In many automation environments color is the attribute that is used for controlling the processes. For example, a manufacturer for bearing shells marks different parts with color markings in red, green and yellow. While packaging and integrating the bearing parts these markings are then used to ensure the correct types get used. The process is complicated by limitions at the marking step which sometimes result in fairly high deviations from the intended colors. The color sensor has to be able to work with these variations and reliably detect the red, green and yellow markings.

Used products:

  • Color sensor PCS-II
  • Reflected-light optical fibers

Solution:

The different yellow, green and red variations observable in the field all get trained into the color sensor. They are then grouped into three groups. This way all tested parts can be reliably detected.

Sorting beverage crates of unknown color according to predefined base colors

Task for the color sensor:

Beverage crates of unknown color have to be sorted based on predefined base colors (e.g. brown, red, blue, green, yellow). It is important that decision of the color sensor matches human perception. Deviating color impressions of sensor and human color processing would result in wrong classification and therefore wrong sorting results.

Benutzte Produkte:

  • Color sensor PCS-II
  • Reflected-light optical fibers

Solution:

The prototypical base colors the sensor has to detect have to be saved in the color sensor. All crates will then be classified according to color distances to the prototypical colors as they would be perceived with a human eye. This procedure reliably classifies all crate variations.

Seperating non-brown glass bottles in a bottling plant

Task for the color sensor:

In a bottling plant only brown glass bottles are allowed to be used. Therefore all non-brown glass bottles have be sorted out before the filling step.

Used products:

  • Color sensor PCS-II
  • transmitted-light optical fiber with M6 end piece

Solution:

The color sensor has beeen trained with the color impression of a brown bottle. A transmitted-light optical fiber were used for this and the final integration. Color tolerances were configured wide enough to let all brown bottles pass and still reliably detect all non-brown colors. The color sensor's switching outputs were wired to a PLC for full automation of the bottle separation step.

Weldseam detection for varying metal colors

Task for the color sensor:

For correct alignment of welded pipes the weldseams have to be reliably detected for pipes in different metal colors.

Used products:

  • 2 channel color sensor PCS-III in difference mode
  • 2 reflected-light fiber optics

Solution:

The task could be solved using a PCS-III color sensor in difference mode. The reflected-light fibers have been placed in parallel in equal distance to the pipe. After balancing the color sensor channels, difference has been set to 0 and tolerances have been set to the color distance between both channels. If no weldseam is detected, the sensor switches its output. If only one of the color sensor channels reports detection, a signal difference occurs and the output gets reset to 0 volts. As color changes occuring on both input channels don't result in signal differences, this solution works for varying metal colors.

Color-testing of distance sensors in bumpers before integration

Task for the color sensor:

When installing distance sensors in automotive bumpers is has to be tested whether the color assignment is correct. There are over 100 possible colors this process has to work with. Colors change frequently. The measuring distance is slightly shifting within a few millimeters. Working distance has to be within 7 to 15cm.

Used products:

  • 2 channel color sensor PCS-III in difference mode
  • 2 transmitted-light optical fibers with A2.0 probe
  • 2 focus optics FOD-A2.0-100 with 95 mm working distance and 12mm measuring spot

Solution:

The optics were placed according to the positions of distance sensor and bumper and inclined about 30° to the object surfaces. Measurement distance was about 95mm. After aligning the sensor channels, a difference of 0 and a tolerance level according to the observed color distance have been configured. If distance sensor color and bumper color match, the output triggers. I cases of deviations between both sensor inputs the switching output is set to 0 volts.

Discrimination of retainer types in airbag systems according to colored plastics insets

Task for the color sensor:

Plastics insets in retainers of airbag systems are color coded. The type can be determined using the color. A distinct and reliable detection of the color is a requirement for automotive safety. 11 different colors have to be detected. At the pastics inset a small area of 2mm width is available for color detection.

Used products:

  • Color sensor PCS-II
  • reflected-light fiber optics
  • focus optics KL-3

Solution:

Level control was implemented measuring white plastics. After that all 11 colors have been trained and tolerance levels have been configured according to minimum color distances between these colors. This setup produced reliable results at production speeds.

Detection of 17 differently colored keypads for automotive dashboards

Task for the color sensor:

A manufacturer of plastics keypads for installation in vehicle cockpits has the task to detect 17 different color variants. These colors are beige and grey nuances with very slight color distances of about delta E = 1 (which is near the border of human perceptibility). A working distance of about 2cm to 4cm has to be used. The solution has to be longtime stable.

Used products:

  • 2 channel color sensor PCS-III in reference mode
  • 1 reflected-light optical fiber with A2.0 probe
  • 1 focus optics KL-M18 with 25mm working distance and 4mm measuring spot

Solution:

Optics KL-M18 has been placed with an inclination of about 30° and a surface distance of about 25mm. After level control using the brightest object all 17 colors could be trained with a tolerance of delta E = 1.

2-channel testing of the color of zippers

Task for the color sensor

A manufacturer of zippers wants to test the color of both textile parts of a zipper. Possible measuring distance is between 2cm and 4cm.

Used products:

  • 2 channel color sensor PCS-III in 2 channel mode
  • 2 transmitted-light fiber optics with A2.0 probe
  • 2 focus optics FOD-A2.0-35 with 30mm working distance to the zippers and 7mm measuring spot

Solution:

The target colors have been trained for each channel and a small tolerance level has been configured. This setup was enough to solve the task reliably.

Detection of glass colors

Task for the color sensor:

Glass of larger thickness has a distinct color (e.g. green). This color allows for inferences of quality and other properties of the glass. When producing glasses the detection of color is therefore an important aspect. In this case color detection has to be implemented by lighting through thick glass strips using special halogen lamps while compensating for extraneous light sources.

Used products:

  • 2-channel color sensor PCS-III in active mode and difference mode
  • 1 reflected-light optical fiber with cross section converter (45x0.3)mm
  • 1 reflected-light optical fiber

Solution:

The first channel was used as measuring channel. Into this sensor input the optical fiber with cross section converter was installed, directed at the glass piece. Behind the glass the halogen light source was positioned so that it shines through the glass. The second color sensor channel has been used as reference channel. The fiber attached to this color sensor input is directed at the halogen light source. With the fibers in place and the lamp switched off both inputs were adjusted for a difference of 0. Now with the lamp activated the glass color could be measured, independently of extraneous light sources.

Foil detection on drink cup blanks

Task for the color sensor:

Polyethylene coated cardboard drink cup blanks have a glued area. This area has to be protected with a transparent foil. If the foil is missing, moisture can enter the cardboard at the glued area, dissolving the glue. Presence of the protective foil has to be ensured. The task is therefore to detect presence of a 3mm wide transparent foil on polyethylene coated cardboard cup blanks.

Used products:

  • 2 channel color sensor PCS-III in difference mode
  • 2 reflected-light optical fibers with 1.5mm² fiber bundles

Solution:

Both reflected-light fibers were positioned in parallel, with an inclination of about 45° and a measuring distance of 1mm relative to the cup blank surface. The L*a*b* color value difference of both inputs has been configured as difference of 0 in the color sensor configuration. The color sensor switches its output if the measured difference is 0. If there is a difference between the color values of both inputs, the color sensor doesn't switch the ouptut. Tolerance values were chosen according to the observed variation of color impressions with and without applied foil, which was about delta E = 4. This setup reliably detected missing foils.

Seam detection and ribbon end detection

Task for the color sensor:

A specific white membrane material is delivered as a short ribbon assembled using red adhesive tapes and packaged on reels. Ribbon ends are marked using black adhesive tape. The membrane material is processed in parallel at a two-track injection molding machine. For controlling reel unwinding both the white membrane itself, the red seams and the black reel end marker have to be detected.

Benutzte Produkte:

  • 2 channel color sensor PCS-III
  • 2 reflected-light optical fibers with M6 probes and 2.5 mm diameter fiber bundles

Solution:

The probes were positioned with an inclination of about 45° and a measuring distance of 8mm relative to the tape. Both color sensor channels were trained with the three colors. The sensor has been set to classification mode. This means measuring and setting tolerances was unneeded for this application to run reliably.

Quality control for injection-molded optical fibers

Task for the color sensor:

Injection molded optical fiber elements have to be tested for light permeability synchronously to the working cycles of the robot taking out the produced parts. Dependent on the scattering bodies incorporated in the material different color values are to be expected. Three levels of dispersion are to be differentiated as distinct quality levels: standard value range, A grade (too light), B grade (too dark).

Used products:

  • 2 channel color sensor PCS-III in reference mode
  • transmitted-light optical fibers with M6 probes

Solution:

The possible color impressions of all three quality levels are trained manually based on a collection of presorted parts. Deviations for the three dispersion levels are configured as tolerance values of a height that ensures no overlap between the levels. The switching outputs of the color sensor get wired to a PLC for separation of the parts.