Color Wheel Speed Detection Temperature Compensation Circuit
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Solution Overview
Problem
The accuracy of color wheel rotational speed measurement is compromised by temperature rises due to poor heat dissipation, affecting the control of the laser current in projector systems.
Innovation Solution
A detecting device with a temperature compensation circuit that adjusts the resistance of the light emitting body's wiring based on ambient temperature, ensuring the driving current remains within a preset range, thereby maintaining measurement accuracy despite temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the color wheel rotational speed detector is used to measure rotational speed, then the control of laser current can be achieved, but the measurement accuracy deteriorates due to temperature rise affecting the detector readings
Solution Approach 1:
The patent introduces a temperature compensation circuit as an intermediary between the light emitting body and the measurement system. This circuit includes a thermistor that detects temperature changes and automatically adjusts the driving current to the light emitting body, compensating for temperature-induced measurement errors without requiring direct temperature sensing at the measurement chip location
Solution Approach 2:
The patent implements a feedback mechanism where the temperature compensation circuit continuously monitors temperature changes (through the thermistor's resistance changes) and adjusts the driving current accordingly. This closed-loop feedback ensures that the light emitting body's output remains stable despite temperature fluctuations, thereby maintaining measurement accuracy
2Measurement precision
If the driving current of the light emitting body is not compensated for temperature changes, then the device complexity is low, but the measurement accuracy deteriorates due to current variation with temperature
Solution Approach 1:
The temperature compensation circuit is designed to be self-regulating, using the thermistor's inherent temperature-dependent resistance characteristics to automatically adjust the driving current. The circuit serves itself by utilizing the natural physical properties of its components rather than requiring external control systems, thereby maintaining measurement accuracy with minimal added complexity
Solution Approach 2:
The patent changes the electrical parameters (resistance and current) of the compensation circuit in response to temperature changes. The thermistor's resistance changes with temperature, which automatically adjusts the circuit's electrical parameters to compensate for temperature effects on the light emitting body, maintaining measurement accuracy through dynamic parameter adaptation
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 effectively reduces the impact of temperature fluctuations on measurement accuracy, ensuring consistent detection of the color wheel's rotational speed and precise control of the light source.
Implementation Method 1
a light emitting body 210 and a temperature compensation circuit 220, where the light emitting body is configured to emit detection light
Implementation Method 2
a third terminal, resistance between the third terminal and the reference ground changing with the external ambient temperature
Data Source
AI summary
A detecting device for detecting a rotation speed of the color wheel includes: a first processing unit, used to compare an external ambient temperature with a preset temperature, and outputs a logic level when the external ambient temperature is greater than the preset temperature; and a light-emitting unit, including a light-emitting body for emitting measurement light, a temperature compensation circuit, wherein the temperature compensation circuit adjusts, according to the logic level and the external ambient temperature, the resistance of a circuit in which the light-emitting body is located, causing a driving current of the light-emitting body to be within a preset current range, a reflection unit disposed on a moving color wheel and used to reflect measurement light, and a measurement and control unit used to receive the measurement light emitted periodically by the reflection unit, and to calculate the number of times that the measurement light enters.