Photoelectronic Sensor Segmented Light Emission for Specular Malfunction Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Retroreflective photoelectronic sensors face instability due to specular malfunctions, where mirror reflected light from specular objects is misinterpreted as nonexistence, leading to incorrect detection results, as the existing light shielding methods fail to differentiate between reflected and mirror reflected light angles.
Innovation Solution
The implementation of a light projecting element with a light emitting area closer to the optical axis and a non-light emitting area farther from it, allowing selective light emission to reduce mirror reflected light incidence on the receiver, thereby enhancing detection stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a light shielding plate with a slit is provided in front of the light receiving element to block mirror reflected light, then specular malfunction is reduced, but detection precision deteriorates because both reflected light and mirror reflected light from different areas of the light projecting element pass through the slit
Solution Approach 1:
The light projecting element is divided into a first light emitting area and a second light emitting area, where the first area projects light that reflects off the reflective plate to the light receiving element, and the second area projects light that would create mirror reflected light. By segmenting the light source and selectively emitting from only the first area, the patent prevents mirror reflected light from reaching the receiver while maintaining detection precision.
Solution Approach 2:
Different areas of the light projecting element are assigned different functions: the first light emitting area is optimized for projecting light toward the reflective plate that will return to the light receiving element, while the second light emitting area is suppressed to prevent creating mirror reflected light. This local differentiation of light emission quality resolves the contradiction between blocking harmful light and maintaining useful light transmission.
2Adaptability or versatility
If light is projected conically from the light projecting element to cover the detection area, then detection coverage is improved, but mirror reflected light reaches the light receiving element causing specular malfunction
Solution Approach 1:
The conical light projection is segmented into two distinct areas: a first light emitting area that projects light at angles that will reflect off the reflective plate back to the light receiving element, and a second light emitting area that projects light at angles that would create mirror reflected light. By activating only the first area, the patent maintains adequate detection coverage while eliminating the reliability issue caused by mirror reflected light.
Solution Approach 2:
The light projection is made non-uniform by suppressing light emission from the second area while maintaining emission from the first area. This creates a localized light distribution pattern that is optimized for reliable detection by ensuring that only light paths leading to correct reflection at the reflective plate reach the light receiving element.
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 configuration effectively suppresses specular malfunctions and improves detection stability by selectively projecting light to prevent mirror reflected light from reaching the receiver, ensuring accurate object detection.
Implementation Method 1
a light projecting lens converging light
Implementation Method 2
a light receiving lens concentrating reflected light from the reflective plate
Implementation Method 3
reflects light back to the light receiving unit
Implementation Method 4
mirror reflected light reflected by the specular surface
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
A photoelectronic sensor (1) capable of improving operation stability is provided. The photoelectronic sensor includes a light projecting unit (14) having a light projecting lens (12) that converges light and a light projecting element (10) that projects light toward a reflective plate (20) via the light projecting lens, and a light receiving unit (34) disposed alongside the light projecting unit and having a light receiving lens (32) that concentrates reflected light from the reflective plate and a light receiving element (30) that receives the reflected light via the light receiving lens. The light projecting element has a light emitting area (11a) located on a side closer to the light receiving element than an optical axis of the light projecting lens and emitting light, and a non-light emitting area (11b) located on a side farther from the light receiving element than the optical axis and not emitting light.