Photoelectric Sensor Shield Wall Blocks Saturation Light
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Solution Overview
Problem
Distance-settable photoelectric sensors face malfunctions due to circuit saturation caused by increased feedback light, which existing solutions attempt to address through complex automatic phase control circuits or reducing sensitivity, leading to shorter detection distances and increased costs.
Innovation Solution
Incorporating a shield wall in the light receiver that blocks excessive reflection light, preventing saturation by reducing the amount of light received, thereby avoiding malfunctions and maintaining detection accuracy across varying distances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the detection object is located close to the photoelectric sensor, then the amount of feedback light increases, but the circuit in the light receiver becomes saturated
Solution Approach 1:
The patent extracts and blocks only the excessive feedback light that causes saturation, while allowing useful reflection light to reach the light receiving element. The shield wall selectively removes the harmful portion of light (causing saturation) without removing the useful portion (needed for detection), thus resolving the contradiction between maintaining detection accuracy and preventing circuit saturation.
Solution Approach 2:
The shield wall creates a localized modification in the light path by blocking light from specific directions (close-range feedback light) while allowing light from other directions (reflection light from objects at set distance) to pass through. This local quality change in light reception enables the system to handle different light conditions selectively, preventing saturation while maintaining detection capability.
2Reliability
If an APC circuit is used to adjust the amount of projection light, then circuit saturation is prevented, but the circuit complexity and cost increase
Solution Approach 1:
The patent replaces the complex electronic APC circuit system with a simple mechanical/optical shield wall structure. Instead of using active electronic control to adjust light levels, the shield wall passively blocks excessive light through its physical presence, achieving saturation prevention without requiring complex control circuits, thereby reducing device complexity and cost.
Solution Approach 2:
The shield wall is implemented as a simple, inexpensive optical component rather than a complex electronic system. This simple structural addition provides effective saturation prevention without the high cost and complexity of APC circuits, aligning with the principle of using simple, cost-effective solutions.
3Reliability
If the dynamic range of the light receiver is increased, then circuit saturation is avoided, but the detection distance becomes shorter
Solution Approach 1:
Instead of changing the light receiver's dynamic range, the patent extracts and blocks only the excessive feedback light that causes saturation. This approach maintains the original detection range because the light receiver's sensitivity and dynamic range remain unchanged, while still preventing saturation by removing the harmful light component.
Solution Approach 2:
The shield wall performs preliminary blocking of excessive feedback light before it reaches the light receiving element. By preventing the harmful light from entering the receiver in the first place, the system avoids saturation without needing to adjust the receiver's dynamic range or sensitivity, thereby maintaining the original detection distance.
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
The shield wall effectively reduces light saturation, preventing circuit malfunctions and maintaining detection accuracy without the need for complex APC circuits or reduced sensitivity, allowing for reliable detection of objects closer than set distances.
Implementation Method 1
a light receiver that has a light receiving element extending from a near-side light-receiving face to a far-side light-receiving face and that receives reflection light with respect to the light projected by the light projector
Implementation Method 2
The shield wall blocks a portion of reflection light from the detection object located at a distance at which the detection object reflects reflection light that causes an amount of light received by the light receiving element to be larger than or equal to a predetermined value
Data Source
AI summary
A light receiver has a shield wall disposed facing a part of a near-side light-receiving face of a light receiving element from an end opposite from a far-side light-receiving face. The shield wall blocks a portion of reflection light from a detection object located at a distance at which the detection object reflects reflection light that causes an amount of light received by the light receiving element to be larger than or equal to a predetermined value.