PMD distance sensors of the OGD series

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PMD sensors allow for more flexible positioning and provide more reliable measurement results

Proven effective in numerous customer applications, our OGD distance sensors with Photonic Mixer Device (PMD) technology are highly versatile problem-solvers for the most challenging tasks. Thanks to the combination of time-of-flight measurement (ToF), background suppression and evaluation of the reflectance, the OGD distance sensors continue to provide stable and precise results where conventional triangulation sensors would fail. In applications with multi-coloured, low-reflectance or shiny surfaces, the OGD sensors detect objects safely – even at extreme alignment angles. A background suppression function ensures maximum reliability even if the sensors are exposed to movements, reflections or poor lighting conditions. The sensors detect dirt on the lens through the reflectance value and alert the operator about cleaning. This increases process reliability.

 

Advantages of PMD distance sensors:

-      detect reflective and light-absorbing objects

-      detect multi-coloured objects

-      detect objects from oblique detection angles

-      detect objects despite background reflections and movements

 

PMD sensors for quality inspection and conveyor belt control

The OGD Long-Range is typically used in conveying, packaging, food processing, metal working and mechanical engineering applications. Based on the reflectance value, it can, for example, perform quality checks of transparent adhesive tapes or seals of different colours. In material handling, conveyor belt stop functions can be implemented using several switching points and an initial speed reduction. Moreover, objects can be evaluated in terms of quality and product size.

 

PMD sensors for precise detection of small parts

The OGD Precision is typically used in error proofing, robotics and handling applications, where it performs precise and reliable inline quality checks and monitors the correct position, orientation and quality of small shiny or black components such as O-rings or toothed wheels. Assembly errors can be detected during production, i.e., before the final quality checks, thus minimising the risk of costly consequential damage such as plant downtimes or batch failures. In the fully automated production of electronic devices, detecting objects from different angles is essential. This can be achieved with the OGD.

 

What are the advantages of time-of-flight measurement compared to conventional triangulation sensor technology?

  • The OGD sensor measures distances with PMD technology, a time-of-flight method that detects objects much more reliably than, for example, CMOS sensors. The sensor especially demonstrates its strength when detecting shiny surfaces or black surfaces with low reflectance. While the OGD can still detect the objects, an CMOS sensor will no longer provide a result.
  • Even multi-coloured objects such as chipboard or pieces of meat are reliably detected thanks to the PMD technology.
  • Background suppression and laser light make the OGD extremely reliable even if exposed to external interference such as movements and reflections.
  • The sensor can detect objects even at extreme alignment angles, while a triangulation sensor must be aligned at an angle of 90° to the object.

 

 

OGD Long Range in the field: conveying and packaging industry

Application example 1:
Verification of the correct sealing of packages

Based on the reflectance value, the OGD Long Range registers whether ready-to-ship packages have been properly sealed with adhesive tape. A signal can be output via IO-Link to feed sealed packages into the further shipping process. Even transparent adhesive tapes are reliably detected by the sensor.

Please note that the reflectance value can vary significantly due to deviations in materials or angles. Thus, tests under real operating conditions and a 90° alignment to the target are recommended.

 

Application example 2:
Two-stage conveyor belt stop function

Background suppression is yet another advantage the OGD provides. The feature comes in handy when implementing a stop function at the end of a conveyor belt. Reflections from metallic surfaces do not affect the sensor, which also reliably detects objects of different colours. The first switch point triggers a speed reduction of the belt. When the object reaches the second switch point, the belt is stopped.

Advantage: Replacing the two units which are typically required for a light barrier, the OGD helps to reduce the purchase, installation and wiring costs. In addition, it can be used in almost any mounting situation, as it can be aligned to the belt at an oblique angle.

 

Food industry

Object detection in product handling

The OGD Long Range reliably detects objects even in unfavourable lighting conditions. It does not even miss reflective or wrinkling materials such as foils, which also often come in colourful or dark designs.

The sensor detects dirt on the lens through the reflectance value via IO-Link and alerts the operator about cleaning. This reduces faulty measurements and increases process reliability.

In food industry processes, IP 69K and the use of plastic instead of glass are frequently a prerequisite. The OGD has IP 67 and a glass lens, but thanks to its long range it can also be placed outside the risk area in some applications.

 

OGD Precision in the field: error proofing

Quality assurance during production

The OGD Precision performs precise and reliable inline quality checks to monitor the correct position, orientation and quality of small shiny or black components such as O-rings or toothed wheels.

Assembly errors such as missing O-rings of 5 mm thickness or more are detected. This error proofing process during production and before final quality checks minimises the risk of costly consequential damage such as plant downtimes or batch failures. At the same time, the inline quality check contributes to long-term and efficient quality assurance. The earlier errors are discovered, the lower the consequential costs are and the sooner improvements can be made.

At an oblique angle, however, the reflectance value of the OGD is no longer reliable since too little light might be reflected.