Optical Sensor Integrator Start Phase Control
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Solution Overview
Problem
Optical sensor arrangements face challenges in accurately converting photocurrent into digital signals due to uncertainties in the starting point, which can be influenced by external light conditions and result in errors, especially under low light conditions or when transitioning from the start phase to the measuring phase.
Innovation Solution
The optical sensor arrangement includes a photodiode, an integrator, a comparator, and a reference capacitor circuit, where charge packages are provided to the integrator input until the comparator input voltage crosses a well-defined switching point, ensuring a precise starting point and minimizing transient signals during the transition to the measuring phase, allowing for accurate light-to-frequency conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If charge packages are provided to the integrator input during the start phase, then the comparator input voltage can be brought close to the comparator switching point, but the starting point becomes uncertain and influenced by external light conditions
Solution Approach 1:
The patent applies preliminary action by implementing a start phase before the measuring phase, during which charge packages are provided to the integrator input to bring the comparator input voltage close to the switching point. This preliminary adjustment ensures that the measurement starts from a well-defined state, eliminating uncertainty about the starting point while maintaining measurement precision.
Solution Approach 2:
The patent uses feedback by continuously monitoring the comparator input voltage during the start phase and adjusting the charge package provision until the voltage reaches the switching point. This feedback mechanism ensures that external light conditions do not affect the stability of the starting point, as the system actively compensates to reach the target voltage level.
2Measurement precision
If the start phase duration is extended to ensure accurate starting point, then measurement precision improves, but response time and productivity decrease
Solution Approach 1:
The patent applies self-service by designing the start phase to automatically terminate when the comparator input voltage crosses the switching point. The system serves itself by using the comparator to detect when the integrator output has reached the target level, eliminating the need for external timing control or manual intervention to determine when the start phase should end.
Solution Approach 2:
The patent implements periodic action through the alternating start phase and measuring phase. The start phase quickly adjusts the integrator output to the switching point, then the measuring phase begins immediately. This periodic structure ensures that each measurement cycle starts from a well-defined state without requiring extended preparation time, thus maintaining both precision and productivity.
3Adaptability or versatility
If the photodiode is coupled to the integrator input during the start phase, then photocurrent can be provided, but transient signals and errors occur during transition to measuring phase
Solution Approach 1:
The patent applies the taking out principle by separating the photodiode coupling from the start phase. The photodiode is excluded from the integrator input during the start phase, and only coupled during the measuring phase. This extraction eliminates the harmful effect of photocurrent during the start phase, preventing transient signals and measurement errors during phase transitions.
Solution Approach 2:
The patent implements dynamics by making the photodiode coupling dynamic rather than static. The coupling between the photodiode and integrator input is controlled to be active only during the measuring phase and inactive during the start phase. This dynamic control allows the system to adapt to different operational requirements, ensuring accurate measurements while avoiding transient signals during phase transitions.
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 enhances the linearity and accuracy of the light-to-frequency conversion, reducing errors and ensuring a well-defined starting point independent of external light conditions, thereby improving the reliability of the optical sensor's digital output.
Implementation Method 1
An optical sensor arrangement often comprises a photodiode as a light detector and measures a photocurrent flowing through the photodiode
Implementation Method 2
The reference capacitor circuit is coupled to the integrator input and is designed to provide a charge package to the integrator input
Data Source
AI summary
An optical sensor arrangement comprises a photodiode (11), an integrator (12) with an integrator input (15) coupled to the photodiode (11), a comparator (13) with a first input (18) coupled to an integrator output (16) of the integrator (12), and a reference capacitor circuit (14) that is coupled to the integrator input (15) and is designed to provide a charge package to the integrator input (15). In a start phase (A), charge packages are provided to the integrator input (15), until a comparator input voltage (VIN) at the first input (18) of the comparator (13) crosses a comparator switching point.