Wearable Ambient Temperature Measurement Using Infrared Averaging
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Solution Overview
Problem
Wearable devices, such as wristwatches, face challenges in accurately measuring ambient temperature due to the influence of human body heat, making it difficult to obtain precise readings without removing the device and waiting for it to equilibrate with the environment.
Innovation Solution
Incorporating an infrared sensor with a control and processing circuit that activates multiple measurements over time to calculate an average temperature value, and using an inclinometer to ensure measurements are taken from relevant orientations, excluding celestial radiation and body temperature influences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a resistive-type sensor or thermocouple is used to measure temperature in a wristwatch, then the temperature measurement function is achieved, but the measurement precision deteriorates due to the substantial influence of human body heat on the watch case temperature
Solution Approach 1:
The patent replaces contact-based thermal sensors (resistive-type sensors or thermocouples) with an infrared sensor that measures temperature remotely through infrared radiation. This substitution eliminates the need for thermal contact between the sensor and the watch case, thereby preventing body heat from contaminating the ambient temperature measurement. The infrared sensor detects infrared radiation from external objects and surfaces, converting it into temperature data without being thermally influenced by the wrist or watch case.
2Ease of operation
If the wristwatch is worn on the wrist for convenient use, then the ease of operation is improved, but the measurement precision deteriorates because the watch case temperature reflects body temperature rather than ambient temperature
Solution Approach 1:
The patent employs an infrared sensor that measures temperature through infrared radiation detection rather than thermal contact. This allows the watch to remain worn on the wrist for convenience while the sensor measures ambient temperature from external sources (walls, furniture, sky, ground) without being affected by body heat. The infrared sensor effectively 'looks at' external objects to determine their temperature, independent of the watch case temperature.
Solution Approach 2:
The patent implements a measurement strategy where the infrared sensor takes multiple temperature measurements at different orientations over time and calculates an average value. By periodically measuring temperatures of various external objects (walls, furniture, sky, ground) from different angles and averaging them, the system obtains a representative ambient temperature that compensates for the fact that the watch is worn on the wrist. This periodic multi-orientation measurement approach ensures accurate ambient temperature reading despite the watch's position on the body.
3Measurement precision
If the infrared sensor takes multiple measurements over time to calculate an average temperature, then the measurement precision is improved, but the loss of time increases due to the period required to obtain sufficient measurements
Solution Approach 1:
The patent implements continuous or periodic temperature measurements by the infrared sensor, taking multiple readings at different orientations and continuously updating the average ambient temperature. Rather than requiring a fixed waiting period, the system continuously accumulates measurements and provides updated temperature readings, transforming a time-consuming batch process into a continuous useful action that delivers precision without significant time loss.
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
Enables accurate and continuous ambient temperature measurement independent of the user's body temperature, providing reliable and precise readings without user intervention.
Implementation Method 1
an infrared sensor (IR sensor) arranged to be able to receive an infrared radiation from outside this wearable device
Implementation Method 2
the processing circuit is arranged to supply temperature values corresponding to at least a portion of the plurality of measurement signals and to take a mean for at least a portion of these temperature values to obtain an average temperature value
Data Source
AI summary
The wearable device incorporates a device for measuring the ambient temperature, which comprises an infrared sensor. In an ambient temperature measurement mode a control circuit activates the infrared sensor several times so that it can supply a plurality of measurement signals over a certain period of time. A circuit for processing measurement signals is then arranged in order to supply temperature values corresponding to at least a portion of the measurement signals and to take a mean for at least a portion of these temperature values to obtain an average temperature value that is considered to be representative of the ambient temperature. The invention also relates to a method for measuring the ambient temperature that can be implemented by means of this wearable device.