Reflective Sensor Optical System for Position Detection Accuracy
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Solution Overview
Problem
Conventional reflective sensors face challenges in achieving both high accuracy in position detection and robustness against changes in distance and angle of the detection target object, leading to trade-offs between robustness and accuracy, which affects toner density and mispositioning detection.
Innovation Solution
A reflective sensor with an optical system that includes at least one lens section, arranged to collect regularly reflected light and diffuse-reflected light in a way that the receiving areas differ by a predetermined range in the movement direction, and are wider in the perpendicular direction, allowing for improved robustness and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the imaging spot is narrowed for minimum spherical aberration to detect position highly accurately, then position detection accuracy is improved, but robustness against change in distance between detection target object and sensor deteriorates
Solution Approach 1:
The light receiving element is divided into multiple regions: a first region for receiving regularly reflected light and a second region for receiving diffuse-reflected light. This segmentation allows independent optimization of each region's function, enabling the first region to maintain narrow imaging spot for high position detection accuracy while the second region provides robustness against distance and angle changes through diffuse light reception.
Solution Approach 2:
Diffuse-reflected light acts as an intermediary to compensate for the low robustness caused by narrow imaging spot. The second region receives diffuse-reflected light that provides information about distance and angle changes, which compensates for the sensitivity of the first region's narrow imaging spot, thereby improving overall robustness without sacrificing position detection accuracy.
2Reliability
If robustness against distance and angle change is improved for toner density detection, then reliability is improved, but position detection accuracy deteriorates
Solution Approach 1:
The light receiving element is segmented into multiple regions with different functions: the first region optimized for position detection with narrow imaging spot, and the second region optimized for robustness with wider light reception for diffuse-reflected light. This segmentation resolves the contradiction by allowing each region to specialize in one function without compromising the other.
Solution Approach 2:
The light receiving element serves multiple functions simultaneously: the first region detects position with high accuracy through regularly reflected light, while the second region provides robustness against distance and angle changes through diffuse-reflected light. This multi-functionality allows the sensor to perform both toner density detection (requiring robustness) and mispositioning detection (requiring accuracy) with a single device.
3Device complexity
If a single sensor is used to detect both toner density and mispositioning, then device complexity is reduced, but measurement precision for both functions deteriorates
Solution Approach 1:
The light receiving element is designed with multi-functionality to perform both toner density detection and mispositioning detection simultaneously. By dividing the light receiving element into multiple regions with different light reception characteristics, the single sensor can accurately detect both functions without requiring separate sensors, thus reducing device complexity while maintaining measurement precision.
Solution Approach 2:
The light receiving element is segmented into multiple regions that can independently process different types of light information. This segmentation enables the single sensor to extract both toner density information (from diffuse-reflected light in the second region) and mispositioning information (from regularly reflected light in the first region) with high accuracy, avoiding the need for multiple separate sensors.
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 solution provides a reflective sensor with enhanced robustness and accuracy in detecting the position of the detection target object, effectively addressing the limitations of conventional sensors by maintaining high accuracy and robustness against changes in distance and angle.
Implementation Method 1
A reflective sensor is arranged such that a light emitting element irradiates a detection target object with light and that a light receiving element reads reflected light from that detection target object. The light receiving element generates a photocurrent corresponding to the intensity of light that the light receiving element has read.
Implementation Method 2
an optical system including at least one lens section each including at least one lens which at least one lens section is disposed on an optical path of light... The optical system is arranged to, in a movement direction in which the detection target object is moving, collect light so that a regularly reflected light receiving area differs in position from a diffuse-reflected light receiving area
Data Source
AI summary
The present invention includes an optical system disposed on an optical path of light that is emitted by a light emitting section, travels to a detection target object, is reflected by the detection target object, and reaches a light receiving section. The optical system, in a sub scanning direction, that is, the direction in which a detection target object is moving, collects light so that the light receiving section has, for light from the light emitting section, a regularly reflected light receiving area and a diffuse-reflected light receiving area that differ from each other in position within a predetermined range. The optical system, in a perpendicular direction that is perpendicular to the movement direction, refracts light so that a light receiving area, which covers the regularly reflected light receiving area and the diffuse-reflected light receiving area, is wider in the perpendicular direction than in the sub scanning direction.