Vision Measuring Device Auto-Focusing Control via Timing Feedback
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Solution Overview
Problem
Conventional vision measuring devices face challenges in achieving accurate and high-speed auto-focusing due to communication delays and device-specific measurement errors, which affect the determination of the correct in-focus position.
Innovation Solution
A vision measuring device that includes an imaging device, a position control device, and a vision measuring system, where the position control device acquires and retains position information based on trigger signals, allowing the system to calculate and compensate for gaps in image acquisition timing, enabling accurate auto-focusing control through dedicated communication wires and serial number association.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If contrast-type auto-focusing is implemented using a simple camera and software configuration, then device complexity is reduced, but measurement precision deteriorates due to communication delays and timing gaps between image shooting and image acquisition
Solution Approach 1:
The patent implements a feedback mechanism where the actual image acquisition timing is detected and used to correct the timing gap. The system detects when images are actually acquired, calculates the timing difference from the intended shooting timing, and uses this feedback to compensate for the gap, ensuring accurate in-focus position determination despite communication delays
Solution Approach 2:
The patent changes the timing parameter dynamically by detecting the actual image acquisition timing and adjusting the position information accordingly. Instead of using fixed timing assumptions, the system modifies the timing parameter based on actual acquisition moments, thereby eliminating the measurement error caused by communication gaps
2Measurement precision
If individual calibration is performed to compensate for device-specific timing gaps, then measurement precision is improved, but ease of operation deteriorates due to complex calibration procedures
Solution Approach 1:
The patent enables the system to perform self-calibration by automatically detecting its own image acquisition timing and calculating the timing gap without external intervention. The system serves itself by using its own operational data to identify and correct its timing errors, eliminating the need for manual individual calibration procedures
3Ease of manufacture
If image transfer is performed using general-purpose communication interfaces, then ease of manufacture is improved, but reliability deteriorates due to indeterminate delays and drop frames from communication confliction
Solution Approach 1:
The patent introduces an intermediary mechanism that detects actual image acquisition timing and position information. This intermediary layer acts as a buffer between the unreliable general-purpose communication interface and the auto-focusing control system, ensuring that even if image transfer experiences delays or drop frames, the timing detection and correction mechanism can still accurately determine the in-focus position
Data Source
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AI summary
A vision measuring device includes: a camera which images a workpiece and transfers image information of the workpiece; a position control unit which controls an in-focus position of the camera and outputs the in-focus position as position information representing a position in a Z-axis direction; and a vision measuring machine which performs vision measurement on the workpiece based on image information and position information. The position control unit acquires and retains position information in response to a trigger signal output from the camera or the position control unit to the other at a certain timing of an imaging period during which the camera images the workpiece. The vision measuring machine calculates position information representing a position of image information in the Z-axis direction based on image information transferred from the camera and position information output from the position control unit, and performs auto-focusing control.