Distance sensors: advantages of time-of-flight measurement compared to triangulation

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.

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.

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.

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.