Dynamic Gain Control for Time-Division Color Light Sensing
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Solution Overview
Problem
Existing light quantity measurement apparatuses for time-division color display projectors suffer from decreased measurement accuracy due to varying sensitivity for red, green, and blue light when using a single photosensor, leading to inconsistencies in projection energy and gradation expression.
Innovation Solution
A light quantity measurement apparatus comprising an optical semiconductor, an amplifier element, a resistor unit, and a controller that optimally adjusts the sensitivity of the optical semiconductor to match the light source's output for each color, ensuring consistent output levels across red, green, and blue light measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single photosensor is used to measure the light quantity of multiple colors, then the device complexity is reduced, but the measurement precision decreases due to large differences in sensitivity for red, green, and blue light
Solution Approach 1:
The patent applies dynamics by making the gain of the amplifier element variable rather than fixed. The controller dynamically adjusts the gain based on the color of light being measured, switching between different gain values for red, green, and blue light. This dynamic adjustment allows a single photosensor to achieve measurement precision comparable to multiple photosensors by adapting its sensitivity to match each color's characteristics.
Solution Approach 2:
The patent changes the electrical parameter (gain) of the amplifier element to compensate for the optical parameter (sensitivity) variations of the photosensor across different wavelengths. By adjusting the gain parameter in response to different colors of light, the system maintains consistent measurement precision without requiring multiple photosensors with different spectral responses.
2Ease of manufacture
If the light quantity of multiple colors is measured with a single photosensor, then the manufacturing cost is reduced, but the measurement accuracy decreases due to differences in projection energy for various colors
Solution Approach 1:
The system dynamically adjusts the amplifier gain based on the detected color of light, allowing a single, simpler photosensor to achieve accurate measurements across multiple wavelengths. This dynamic adaptation eliminates the need for multiple specialized photosensors, reducing manufacturing complexity while maintaining measurement accuracy for red, green, and blue light despite their different projection energies.
Solution Approach 2:
The controller receives feedback about the color of light being measured and adjusts the amplifier gain accordingly. This feedback mechanism enables the system to compensate for the photosensor's varying sensitivity and the light source's varying projection energy across different colors, maintaining measurement accuracy while using a single photosensor.
3Device complexity
If gain is not adjusted for different colors, then the device complexity is reduced, but the output level varies significantly for different colors, reducing A/D converter efficiency
Solution Approach 1:
The amplifier element's gain is made dynamic and controllable, allowing the system to optimize the output signal level for each color of light. This ensures that the A/D converter operates within its optimal dynamic range for red, green, and blue light measurements, improving measurement productivity and efficiency without significantly increasing device complexity, as the gain control is implemented through software-based controller logic.
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 solution significantly improves measurement accuracy by maintaining consistent output levels for each color, reducing quantization noise and effectively utilizing the dynamic range of the A/D converter, resulting in higher precision light quantity measurements.
Implementation Method 1
The optical semiconductor receives a plurality of colors of light emitted from a light source in a time division. The amplifier element converts optical current flowing to the optical semiconductor into voltage
Data Source
AI summary
The light sensitivity controlling apparatus comprises an optical semiconductor, an amplifier element, a resistor unit, an A/D converter, and a controller. The optical semiconductor receives a plurality of colors of light emitted from a light source in a time division. The amplifier element converts optical current flowing to the optical semiconductor into voltage by receiving the plurality of colors of light. The resistor unit switches the gain for converting the optical current inputted to the amplifier element into voltage, for each of the plurality of colors of light. The A/D converter converts the voltage outputted by the amplifier element from an analog signal into a digital signal. The sensitivity controlling apparatus controls the resistor unit so that the output level corresponding to the various colors of light outputted from the A/D converter will remain substantially same level.