Color Sensing Circuit Charge Storage Integration
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Solution Overview
Problem
Existing color sensors are space inefficient due to large photodiode areas and temperature-dependent external resistors, which complicate circuit design and output consistency across temperature variations.
Innovation Solution
A color sensing circuit that integrates a light detector, storage device, and signal processing circuit with switches, eliminating the need for external components and operational amplifiers, utilizing a single integrated circuit with charge storage and controlled charge accumulation for improved sensitivity and robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If external components and operational amplifiers are used in the color sensor, then the circuit can convert photocurrent to output voltage, but the sensor becomes space inefficient due to large photodiode areas and large feedback resistors
Solution Approach 1:
The patent merges the light detector, charge storage device, and signal processing circuit into a single integrated circuit structure. The storage device is directly coupled to the light detector, and the signal processing circuit is integrated with the storage device, eliminating the need for separate external components and operational amplifiers. This integration significantly reduces the overall sensor area while maintaining the photocurrent to voltage conversion capability.
2Power
If large external feedback resistors are used to convert large photocurrents to output voltage, then the color sensor can operate with higher photocurrents, but the sensor design becomes dependent on temperature variations
Solution Approach 1:
The patent replaces the traditional operational amplifier-based transimpedance amplifier with a charge storage device and signal processing circuit. This substitution eliminates the need for large external feedback resistors that are highly temperature-dependent. The signal processing circuit processes the charge signal in a manner that is substantially independent of temperature variations, thereby improving temperature stability while maintaining the ability to handle higher photocurrents.
3Ease of manufacture
If external components are mounted on a printed circuit board, then the color sensor can be implemented with adjustable gain, but the sensor requires higher photocurrents to reduce noise sensitivity
Solution Approach 1:
The patent implements dynamic gain control through the signal processing circuit, which can adjust its operation based on the charge signal characteristics. The integrated design allows the gain to be optimized for different lighting conditions without requiring higher photocurrents. The circuit dynamically adapts to maintain optimal signal-to-noise ratio across varying light levels, eliminating the need for excessively high photocurrents that would be required with fixed external component designs.
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 more compact, temperature-stable, and sensitive color sensing system with reduced noise sensitivity and improved illuminance range, enabling efficient color detection across various applications.
Implementation Method 1
The photodiode 4 converts color light into a corresponding current that represents the incident light
Data Source
AI summary
The color sensing circuit includes a light detector to receive light and to generate a signal that is dependent on the received light. The light detector includes a first electrode coupled to a first node and a second electrode coupled to a second predetermined signal. A storage device is provided that includes a first node and a second node coupled to the second predetermined signal. A first switch is provided that selectively couples the first node with the first electrode of the storage device based on a charge control signal. A signal processing circuit is provided that includes a first electrode and an output to generate an output signal that represents the light received by the light detector. A second switch is also provided that selectively couples the first electrode of the storage device with the first electrode of the signal processing circuit based on an evaluate control signal. The signal processing circuit selectively asserts the charge control signal and evaluate control signal.