Optical Proximity Sensor Digital Calibration for Leakage Compensation
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Solution Overview
Problem
Conventional optical proximity sensors face challenges in accurately determining distance due to leakage currents and deviation values caused by energy reflection, which conventional calibration circuits fail to completely compensate, leading to incomplete sensing and space occupancy issues with subtractors.
Innovation Solution
The optical proximity sensor employs a digital calibration circuit with an analog-digital converter and digital calibration method that counts pulse waves of reflected signals to obtain calibration codes, eliminating leakage currents and deviation values, thereby replacing the need for subtractors and enhancing sensing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional calibration circuits are used to compensate for leakage currents and deviation values, then some calibration is achieved, but the compensation is incomplete and space is occupied by subtractors
Solution Approach 1:
The patent replaces the conventional analog calibration circuit with a digital calibration circuit that uses an analog-to-digital converter (ADC) to convert analog signals to digital signals for processing. This substitution of digital processing for analog circuitry reduces the need for physical subtractor components and occupies less space while achieving complete compensation for leakage currents and deviation values through digital calculation.
Solution Approach 2:
The patent changes the calibration approach from analog parameter adjustment to digital parameter processing. By converting the calibration signals to digital domain and performing calibration calculations digitally, the system achieves more precise and complete compensation while reducing hardware complexity and space requirements.
2Measurement precision
If subtractors are used in conventional calibration circuits, then calibration can be performed, but space is occupied and sensing is incomplete
Solution Approach 1:
The patent eliminates the need for physical subtractor components by replacing them with digital processing operations. The analog-to-digital converter converts calibration signals to digital form, and digital logic circuits perform the subtraction operation virtually, thereby occupying minimal space while achieving complete sensing calibration.
3Reliability
If conventional calibration methods are used, then basic calibration is achieved, but leakage currents and deviation values are not completely eliminated
Solution Approach 1:
The patent uses digital signal processing to achieve complete elimination of leakage currents and deviation values. The digital calibration circuit can precisely calculate and subtract these error components from the measured signals, achieving more complete and reliable calibration compared to conventional analog methods.
Solution Approach 2:
The patent implements a feedback mechanism where the digital calibration circuit continuously monitors and compensates for leakage currents and deviation values. By using the counted pulse wave information to adjust and refine the calibration process, the system achieves complete elimination of these error sources and improves overall measurement precision.
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 effectively eliminates leakage currents and deviation values, improving distance sensing accuracy and reducing space occupancy, allowing for precise calibration without the limitations of subtractors.
Implementation Method 1
A test light emitted by the light transmitter is reflected by the cover to form a first reflected analog signal to the light receiver
Implementation Method 2
The analog-digital converter circuit is configured to convert the first reflected analog signal into a first reflected digital signal
Implementation Method 3
A current of the first reflected analog signal charges the capacitor to have a first capacitor voltage
Data Source
AI summary
An optical proximity sensor with a digital calibration circuit and a digital calibration method are provided. In a test mode, a test light emitted by a light transmitter is reflected by a cover of an electronic device to form a first reflected analog signal to a light receiver. A digital calibration circuit counts the first number of pulse waves of a first reflected digital signal. In a calibration mode, a light is emitted to a detected object through the cover and then is reflected by the detected object to form a second reflected analog signal to the light receiver. When the digital calibration circuit counts the number of pulse waves of a second reflected digital signal up to the first number, the digital calibration circuit clears the first number and then recounts the number of pulse waves of the second reflected digital signal to obtain the second number.