Pepperl+Fuchs Blog

3 Types of Automation Light Grids

Posted by Michael Turner on Thu, Aug 30, 2012

Automation light grids exist in many forms and offer solutions to applications from simple to complex. With sizes ranging from small to large, and with resolutions from fine to coarse, nearly every sensor manufacturer offers a light grid.  

Compared to single beam sensors, light grids offer more detection coverage over a defined area.

Construction of a light grid transmitter unit involves stacking a number of light emitters in parallel and confining them to a single housing. Likewise, the receiver unit combines a number of receiver elements into a separate housing. The end result is a special variant of the single-beam sensor; a thru-beam sensor containing a grid of light beams.  The operating principle of a thru-beam light grid is simple; however, selecting a specific model to meet the needs of the application is much more challenging as output options, configuration methods, and interface types vary greatly. In general, most automation light grids can be categorized into one of two general types: switching and measuring. However, a new automation light grid category to recently emerge is the intelligent light grid.

Switching light grids

Switching light grid applicationSwitching light grids are the most basic type, offering only one or two discrete outputs used to indicate object presence or absence and having no means for object measurement. Major benefits of using a switching light grid are low cost, simple installation, fast operation, and easy configuration. Switching light grids are well suited for applications where single-beam sensors are not reliable enough or when a defined area of coverage is required.

Watch the video: Switching light grid for elevator and doorway monitoring.

Common applications for switching light grids

  • Parts ejection
  • Object counting
  • Edge guiding
  • Elevator and doorway monitoring
  • Leading edge detection
  • Overhang detection

Measuring light grids

Measuring light grid applicationMeasuring light grids provide superior application flexibility and control by offering at least one means of object measurement. This can be one or several analog outputs. Alternatively, measurement data may be transmitted by communication interfaces such as IO-Link, Ethernet, PROFIBUS, or DeviceNet. Some manufacturers may also include one or two discrete outputs for added control and flexibility. Compared to switching light grids, measuring light grids are significantly more expensive and typically require PC software for the configuration.

Common applications for measuring light grids

  • Object sizing and profiling
  • Product guiding and positioning
  • Web tensioning control
  • Height measurement
  • Dimensional inspection

Intelligent light grids

Intelligent light grid applicationIntelligent light grids share similarities with both switching light grids and measuring light grids.  They offer many of the benefits of both switching and measuring light grids including low cost, fast response, high-level configuration, and superior application flexibility. But unlike a switching light grid, they may have numerous discrete outputs. And rather than offering an analog output or means of object measurement as characterized by a measuring light grid, intelligent light grids provide value and flexibility through integrated evaluation functions such as object or hole identification, beam blanking, and height monitoring.

These functions are built-in or stored on the device’s internal microprocessor. This eliminates the need for external configuration with PC software by allowing the functions to be enabled or disabled directly on the device. The affordability and flexibility of an intelligent light grid allow it to be used in many of the same applications as switching and measuring light grids.

Watch the video: Automotive and material handling applications shown are overhang detection, height monitoring, and object identification.

Common applications for intelligent light grids

  • Parts ejection
  • Object counting
  • Edge guiding
  • Elevator and doorway monitoring
  • Leading edge detection
  • Overhang detection
  • Object profiling
  • Product positioning
  • Web tensioning control
  • Height monitoring


Topics: Applications, Light Grids, Photoelectric Sensors

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