Proximity Sensor Temperature Compensation Using Internal Oscillators
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Solution Overview
Problem
Conventional proximity sensors experience malfunctions due to temperature-related changes in sensing values, particularly in long-term grip detection, and struggle with accurate temperature compensation, especially when multiple sensing channels are involved, leading to deviations in IC chip performance.
Innovation Solution
Incorporating an internal temperature sensor within the proximity sensor chip, which generates variable clock signals based on temperature characteristics and uses a small ring oscillator to enhance resolution, allowing for temperature compensation through external data acquisition without heat generation, thereby improving accuracy and reducing deviations between ICs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an ADC-based temperature sensor is used to improve temperature sensing resolution, then measurement precision is improved, but device complexity and area increase due to requiring high-resolution ADC circuits
Solution Approach 1:
The patent extracts the temperature sensing function from the complex ADC-based temperature sensor and implements it using a simple ring oscillator circuit. The ring oscillator's frequency naturally varies with temperature, providing temperature sensing capability without requiring high-resolution ADC circuits, bandgap references, or complex amplifiers.
Solution Approach 2:
The patent replaces the electronic ADC-based measurement system with a frequency-based oscillation system. Instead of using voltage measurements requiring ADC conversion, the system uses frequency measurements from the ring oscillator, which can be counted and measured with simple digital circuitry, thereby reducing device complexity.
2Reliability
If the proximity sensor chip is placed near heat sources to improve sensing performance, then sensing capability is improved, but temperature stability deteriorates causing sensing value drift
Solution Approach 1:
The patent implements a feedback mechanism where the ring oscillator continuously monitors the temperature at the sensor location and provides real-time frequency information. This frequency data is used to compensate for temperature-induced drift in the proximity sensing values, allowing the system to maintain accurate sensing even when placed near heat sources.
Solution Approach 2:
The patent changes the operating parameter from voltage-based sensing to frequency-based sensing. The ring oscillator's frequency serves as a temperature-compensated reference that naturally adjusts with temperature changes, allowing the proximity sensor to compensate for thermal effects by comparing sensing values against the temperature-varying frequency reference.
3Device complexity
If a single reference channel is used to reduce device complexity, then device complexity is reduced, but measurement precision deteriorates when multiple sensing channels are present due to inability to compensate for local temperature variations
Solution Approach 1:
The patent segments the temperature compensation function by placing multiple ring oscillators at different locations corresponding to different sensing channels. Each local reference channel independently monitors temperature at its specific location, enabling precise local temperature compensation without requiring a complex centralized reference system.
Solution Approach 2:
The patent creates a universal temperature compensation mechanism where each ring oscillator serves dual purposes: it acts as both a temperature sensor for its local channel and as a frequency reference for proximity sensing. This multi-functional approach provides accurate temperature compensation across multiple channels while maintaining simple circuitry.
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 internal temperature sensor enables more accurate proximity sensing by compensating for temperature-related changes, achieving high-resolution temperature data without significant area increase, and allowing for precise temperature compensation across multiple sensing channels.
Implementation Method 1
generating first clock signals variable according to temperature characteristics through a first oscillator of the internal temperature sensor
Implementation Method 2
generating third clock signals independent of temperature change through a second oscillator of the internal temperature sensor
Implementation Method 3
generating second clock signals at time intervals set according to a setting condition corresponding to the first clock through a timer of the internal temperature sensor; counting the second clock signals using the third clock signals through the counter of the internal temperature sensor
Data Source
AI summary
A proximity sensor is provided with multiple channels and a proximity sensor chip (IC) connected to the multiple channels through a sensing line. The proximity sensor chip (IC) includes an internal temperature sensor, senses a first sensing value through the multiple channels, senses a second sensing value through the internal temperature sensor, and compensates the first sensing value through addition or subtraction of the second sensing value with respect to the first sensing value. The internal temperature sensor includes: a clock signal generator including a first oscillator and generating first clock signals variable according to temperature characteristics; and a temperature compensator generating second clock signals according to a setting condition corresponding to the first clock signals generated from the clock signal generator and outputting the second sensing value by counting the second clock signals through a second oscillator generating reference clock signals independent of temperature change.