Optical Limit Switch with Slit Plunger for Position Detection
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Solution Overview
Problem
Conventional limit switches require time-consuming adjustments using an adjusting screw to accurately detect the position of a displacement member, especially when multiple positions need to be detected, leading to inefficiency and increased effort.
Innovation Solution
A switch design incorporating a displacement member with a light emitting element and a light receiving element, where the displacement member has openings that change the light incidence amount, allowing for easy signal output based on set threshold values, eliminating the need for an adjusting screw by comparing the characteristic amounts outputted from the light receiving element with pre-set values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a contact mechanism is used to detect the position of the displacement member, then the position can be detected, but an adjusting screw is required to eliminate differences caused by dimension variations, which increases the adjusting task time and effort
Solution Approach 1:
The patent replaces the mechanical contact mechanism with an optical detection system. A light emitting element emits light toward a light receiving element, and the displacement member with openings modulates the light transmission. This substitution eliminates the need for mechanical adjustment while achieving accurate position detection through optical characteristic amounts.
Solution Approach 2:
The displacement member itself serves dual functions: it is both the object being detected and the component that modulates the light signal for detection. The openings in the displacement member automatically create the characteristic light pattern that enables position detection without requiring separate adjustment mechanisms.
2Adaptability or versatility
If multiple contact mechanisms are provided to detect multiple positions of the displacement member, then multiple positions can be detected, but the adjusting task time increases significantly as each contact mechanism requires individual adjustment
Solution Approach 1:
The single optical detection system serves multiple positions simultaneously. The light emitting element and light receiving element detect different positions of the displacement member through the characteristic light transmission patterns created by the openings, eliminating the need for multiple separate detection mechanisms and their individual adjustments.
Solution Approach 2:
Multiple position detection functions are merged into a single optical detection system. Instead of having separate contact mechanisms for each position, the patent combines all position detection capabilities into one integrated optical system that reads the position information from the light transmission pattern.
3Measurement precision
If an adjusting screw is provided for precise position detection, then the detection accuracy can be improved, but the device complexity increases due to the additional adjustment mechanism
Solution Approach 1:
The patent extracts the adjustment function from the detection system. Instead of having an adjusting screw as part of the detection mechanism, the design uses the inherent optical properties of the displacement member's openings to provide detection accuracy without requiring separate adjustment components.
Solution Approach 2:
The mechanical adjusting screw is replaced with an optical detection approach. The light emitting and receiving elements, combined with the displacement member's opening pattern, provide the necessary detection accuracy without mechanical adjustment components, thereby reducing device complexity.
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
Enables efficient and accurate signal output corresponding to the desired position of the displacement member without the need for manual adjustments, reducing effort and time required for setting and detection.
Implementation Method 1
a light emitting element for emitting light from a light emitting surface, and a light receiving element having a light receiving surface facing the light emitting surface, the light receiving element for outputting a characteristic amount indicating an amount of the light incident on the light receiving surface
Implementation Method 2
an opening through which the light passes is formed in the displacement member in such a manner that the amount of the light incident on the light receiving surface among the light emitted from the light emitting surface is changed in accordance with displacement of the displacement member
Data Source
AI summary
A slit is formed in a plunger of a limit switch in such a manner that an amount of light incident on a light receiving element is changed in accordance with displacement of the plunger. The limit switch is provided with a setting processing unit (123) for setting a voltage value outputted from the light receiving element as a threshold value when a setting instruction is inputted in a state where the plunger is displaced to a designated position by a user, a position detecting unit (113) for performing detection processing of detecting whether or not the plunger is placed at a closer position to a reference position than to the designated position by comparing the set threshold value and the voltage value outputted from the light receiving element, and an output signal controlling unit (119) for outputting a signal based on a result of the detection processing. Thereby, the switch for outputting the signal in accordance with a position of a displacement member, the switch being capable of easily outputting the signal in accordance with a desired position of the displacement member without need for an adjusting screw can be provided.