Image Sensor Temperature Measurement Error Cancellation
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Solution Overview
Problem
Existing image capturing systems face inaccuracies in temperature measurement due to manufacturing errors and variations in element characteristics, which are not adequately addressed by current technologies.
Innovation Solution
An image capturing system that includes a temperature signal output unit and a reference signal output unit on the same substrate, where the reference signal is used to correct the temperature signal, thereby reducing errors caused by manufacturing variations and improving measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a diode is used as a temperature sensor to measure temperature based on diode voltage difference, then temperature measurement capability is achieved, but measurement precision deteriorates due to manufacturing errors and element variations
Solution Approach 1:
The patent creates a reference signal that copies the temperature characteristics of the diode but eliminates manufacturing errors. By generating a reference voltage that mirrors the diode's temperature-dependent behavior while using ideal component values, the system can subtract this error-free reference from the actual diode measurement to obtain accurate temperature readings despite variations in real component characteristics.
Solution Approach 2:
The patent changes the parameters of the reference signal generation circuit to match the temperature coefficients of the diode sensor. By carefully selecting resistor ratios and voltage levels in the reference circuit, the system creates a reference signal whose temperature dependence matches that of the actual temperature sensor, allowing error cancellation through differential measurement.
2Measurement precision
If temperature measurement is performed using diode voltage characteristics, then temperature detection is enabled, but measurement precision deteriorates due to non-linear current-voltage characteristics
Solution Approach 1:
The reference signal circuit copies the non-linear voltage-temperature relationship of the diode by using identical or matched diodes in the reference path. This allows the system to pre-characterize and compensate for non-linear effects by comparing the actual diode response against the known reference response across the temperature range.
Solution Approach 2:
The system uses the reference signal as feedback to continuously correct for non-linearities. By comparing the actual diode voltage against the reference diode voltage (which has known characteristics), the system can calculate compensation factors and apply corrections to maintain high measurement precision across varying temperature and current conditions.
3Measurement precision
If a reference signal output unit is added to correct temperature signals, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent merges the reference signal generation functionality with the existing temperature sensor circuit by using a second diode and shared current sources on the same substrate. This integration approach minimizes additional complexity while achieving error cancellation, as the reference and measurement paths share common components and processing infrastructure.
Solution Approach 2:
The reference signal output unit serves multiple functions: it provides error cancellation, enables temperature compensation, and can be used for calibrating the measurement system. This multi-functionality justifies the added complexity by delivering multiple benefits from a single circuit addition.
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 system achieves improved temperature measurement accuracy by canceling out error factors and noise, ensuring precise temperature detection even with variations in element characteristics.
Implementation Method 1
obtaining a temperature measurement value based on the difference of a diode voltage generated when a diode current is changed
Data Source
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AI summary
An image capturing apparatus includes a plurality of pixels arranged on a substrate, a temperature signal output unit arranged on the substrate and configured to output a temperature signal representing a temperature, and a reference signal output unit arranged on the substrate and configured to output a reference signal used to correct the temperature signal. The temperature signal output unit and the reference signal output unit are arranged in regions different from each other on the substrate.