Light Grid Time Multiplexing Cycle Time Reduction
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Solution Overview
Problem
Conventional light grids face challenges in detecting transparent objects and have long cycle times due to the need for sequential activation of all monitoring beams, which increases response time and manufacturing costs, and are inefficient in tracking switching thresholds.
Innovation Solution
Implementing time multiplexing for object detection signals and using a pre-failure threshold to dynamically adjust switching thresholds, allowing for parallel activation of monitoring light beams in groups and reducing cycle time while maintaining low communication overhead and avoiding bus conflicts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sequential activation of all monitoring beams is used, then beam interruption detection is reliable, but cycle time increases significantly
Solution Approach 1:
The patent divides the set of monitoring beams into multiple groups that can be activated in parallel. Instead of sequentially activating all beams one by one, the system simultaneously activates multiple groups, each containing multiple beams. This segmentation allows the cycle time to be reduced proportionally to the number of parallel groups while maintaining reliable detection through group-based evaluation logic.
Solution Approach 2:
The patent implements periodic activation of beam groups with structured timing. Each group is activated in time-sliced periods, and the evaluation logic is updated periodically to reflect the current group's status. This periodic structure enables systematic parallel processing while maintaining the reliability of interruption detection through regular evaluation cycles.
2Loss of time
If parallel activation of multiple monitoring beams is implemented, then cycle time is reduced, but bus conflicts occur when multiple receivers transmit simultaneously
Solution Approach 1:
The patent segments the beam activation into distinct groups that are activated in parallel time slices. Each group's receivers transmit their status during their designated time slot, preventing simultaneous transmissions from different groups. This segmentation of communication time slots eliminates bus conflicts while maintaining the speed benefits of parallel beam activation.
Solution Approach 2:
The patent implements periodic time-sliced activation where each beam group is activated and communicates during specific periodic intervals. The evaluation logic is updated periodically after each group's transmission window, ensuring that bus access is structured and conflict-free while maintaining efficient parallel processing across multiple groups.
3Loss of information
If conventional cycle-based evaluation is used, then beam assignment is unambiguous, but response time and switching frequency are limited
Solution Approach 1:
The patent segments the evaluation process to work at two levels: group level and individual beam level. The evaluation logic maintains clear beam assignment information by tracking which specific beam within each group was interrupted, while the group-based parallel activation enables faster overall response. This segmented evaluation preserves assignment clarity while achieving faster response times through parallel group processing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces cycle time, improves detection of transparent objects, and minimizes effort in threshold tracking, ensuring reliable and efficient operation with reduced manufacturing costs.
Implementation Method 1
A plurality of light transmitters 14, each with a light source 16... span a monitoring light beam 38 between them
Implementation Method 2
a plurality of light receivers 22 each assigned to a light transmitter 14 and each having a light receiving element 24... recognize whether the monitoring light beam 38 assigned to it is interrupted
Data Source
Figure 1
Figure 2~4
Figure 3
AI summary
A light grid (10) is described, comprising a plurality of light transmitters (14) for each emitting a monitoring light beam (38) and a plurality of associated light receivers (22) for generating an object detection signal (42a-d) depending on the reception of the monitoring light beam (38). The grid is further described as comprising a controller (30, 32) configured to divide the monitoring light beams (38) into groups and to activate the monitoring light beams (38) of the groups sequentially, whereby in a group-wise parallel monitoring sequence, one monitoring light beam (38) of each group is activated in parallel. The grid is also described as comprising a first bus (34) via which the object detection signals can be output from the light receivers (22, 26) to the controller (32). The light receivers (22, 26) are configured to output the object detection signals to the controller (32) using a time-division multiplexing method.