Position Detection Device with Dynamic Threshold for Optical Gear Systems
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Solution Overview
Problem
Existing position detection devices in light source systems face accuracy issues due to dust accumulation on optical elements, leading to inadequate detection of gear positions, especially when light emission and reception units degrade.
Innovation Solution
A position detection device with a sensor unit that adjusts its detection threshold based on the light reception amount, setting it to a value between the full and suppressed light reception levels, ensuring accurate detection of gear positions even with degraded units, and incorporating a control unit to adjust the gear's origin position and rotation angle of optical elements like phase difference plates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a gear-based optical device is used to adjust the phase difference plate, then the rotation angle can be controlled, but dust accumulates on the gear and phase difference plate causing deterioration of polarization conversion function
Solution Approach 1:
The patent extracts the harmful gear mechanism from the optical path by using a belt transmission system instead. The motor drives a pulley that transmits power through a belt to rotate the phase difference plate, eliminating the gear that would accumulate dust and contaminate optical elements.
2Measurement precision
If a fixed threshold position detection device is used, then the gear position can be detected, but detection accuracy deteriorates when light emission and reception units degrade
Solution Approach 1:
The patent implements dynamic threshold adjustment in the position detection device. Instead of using a fixed threshold, the system automatically adapts the detection threshold based on the actual light reception conditions, ensuring accurate gear position detection even when the light emission or reception units degrade over time.
Solution Approach 2:
The position detection device incorporates feedback mechanisms that monitor the light reception amount and adjust the detection threshold accordingly. This feedback loop ensures that the system maintains detection accuracy by compensating for degradation in the light emission or reception units.
3Reliability
If the light reception threshold is set too high, then degraded units can be compensated, but false detection occurs when light is properly received
Solution Approach 1:
The system dynamically adjusts the detection threshold based on real-time light reception measurements rather than using a statically high threshold. This allows the system to compensate for unit degradation while maintaining accurate detection by adapting to the actual optical conditions.
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 enhances the accuracy of gear position detection and maintains optimal light emission by reducing dust accumulation on optical elements, improving the overall performance and reliability of light source devices and projectors.
Implementation Method 1
a sensor that includes a light emission unit and a light reception unit receiving light emitted from the light emission unit
Implementation Method 2
a gear that is disposed at a position facing the sensor and is rotated by power from the driving unit; and an incidence suppression portion suppressing incidence of at least a part of the light emitted from the light emission unit on the light reception unit according to rotation of the gear
Implementation Method 3
The phase difference plate has a function of converting a polarization direction of incident linearly polarized light
Data Source
AI summary
A position detection device includes: a sensor that includes a light emission unit and a light reception unit receiving light emitted from the light emission unit; a driving unit; a gear (transmission gear) that is disposed at a position facing the sensor and is rotated by power from the driving unit; and a control unit that drives the driving unit based on an amount of light received by the light reception unit and detected by the sensor.