Ear Thermometer Mode Switching Circuit for Power Reduction
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Solution Overview
Problem
Conventional ear thermometers face challenges in miniaturization, power consumption, circuit complexity, and cost due to their design, making them unsuitable for continuous and long-term temperature measurement, especially in stable ambient conditions.
Innovation Solution
A compact ear thermometer with a microcontroller, thermistors, and a simplified temperature measuring circuit, where the microcontroller switches between flash and run modes without a dedicated mode switch, and a mode switching circuit that reduces power consumption by controlling voltage levels, allowing for continuous temperature measurement with reduced size and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a conventional ear thermometer design is used, then temperature measurement capability is provided, but the device is large in scale and cannot be miniaturized
Solution Approach 1:
The patent combines the microcontroller and temperature sensor into a single integrated probe unit that connects to a separate measuring apparatus via a cable. This merging of components enables miniaturization of the thermometer body while maintaining full functionality through the distributed architecture where the measuring apparatus handles complex processing tasks.
Solution Approach 2:
The thermometer system is divided into two functional segments: a compact probe containing only essential components (microcontroller, sensor, battery) for miniaturization, and a separate measuring apparatus for complex signal processing and display. This segmentation allows each part to be optimized independently for its specific requirements.
2Use of energy by moving object
If a conventional ear thermometer design is used, then temperature measurement is possible, but power consumption is high
Solution Approach 1:
The measuring apparatus performs temperature measurements periodically rather than continuously, activating the sensor and microcontroller only when measurement is required. This periodic operation significantly reduces power consumption while still providing continuous monitoring capability through scheduled measurement cycles.
Solution Approach 2:
The probe contains a built-in battery that autonomously powers the microcontroller and sensor without requiring external power connection during measurement. This self-powered design eliminates the need for continuous external power supply, reducing overall system power consumption while enabling prolonged operation.
3Ease of manufacture
If a conventional ear thermometer design is used, then basic temperature measurement is provided, but manufacturing cost is high
Solution Approach 1:
The probe is designed as a disposable, low-cost component that can be easily manufactured and replaced. By making the probe inexpensive and single-use, the system reduces overall manufacturing costs while the durable measuring apparatus is reused across multiple probes and applications.
Solution Approach 2:
The complex circuitry and processing functions are extracted from the probe and placed in the separate measuring apparatus. This extraction allows the probe to be manufactured with simple, inexpensive components while the complex functionality is consolidated in a reusable unit, reducing overall system cost.
4Duration of action of stationary object
If a conventional ear thermometer design is used, then temperature measurement is possible, but it cannot perform continuous and long-term measurement
Solution Approach 1:
The measuring apparatus maintains continuous readiness to perform measurements through periodic activation of the probe, ensuring uninterrupted temperature monitoring capability. The system transitions between measurement and idle states smoothly, maintaining continuous useful action without requiring complex continuous operation circuits in the probe.
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 continuous, long-term temperature measurement with reduced power consumption and lower costs, making it suitable for stable ambient conditions and mass production, while maintaining accuracy within the body temperature range.
Implementation Method 1
the probe (2) includes a temperature measuring first sensor (25) and a correcting second sensor (26) which are thermistors
Implementation Method 2
An infrared absorbing film of the thermopile (a part where the infrared absorbing film and hot junction are integrated, refer to 116 of Fig. 16) absorbs infrared rays from a measuring object and increases the temperature thereof
Implementation Method 3
the thermopile produces a potential difference depending on a temperature difference between a cold junction and a hot junction (the Seebeck effect)
Implementation Method 4
there is arranged a cover (114) to surround the same with an air layer (112) and resin (113) serving as heat insulating materials
Data Source
Figure 1
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AI summary
A measuring apparatus for an ear thermometer comprising: a common voltage line; a built-in battery serving as a power source; a connector to receive a connector of the probe, having a common voltage terminal connected to the common voltage line; a flash-type microcontroller to control a temperature sensor of the probe, receive a resistance value output signal corresponding to a measured temperature from the temperature sensor, convert the signal into a digital temperature value, and output the digital temperature value, the microcontroller having a test port, a program write port, and a common voltage port connected to the common voltage line, establishing a flash mode when a HIGH voltage higher than a first predetermined voltage is applied to the test port, to enable a program to be written through the write port, and establishing a run mode when a LOW voltage lower than the first predetermined voltage is applied to the test port; a voltage regulator having an input side connected to the common voltage line, to provide a constant reference voltage; and a mode switching circuit connected to the common voltage line, to apply the HIGH voltage to the test port of the microcontroller when a common voltage is higher than a second predetermined voltage, apply the LOW voltage to the test port of the microcontroller when the common voltage is lower than the second predetermined voltage, and bypass a leakage current passing from the common voltage line to the mode switching circuit toward an output of the voltage regulator so as to combine them together, the connector having the common voltage terminal, a battery power source terminal connected to the built-in battery, a program write terminal connected to the write port of the microcontroller, and a sensor connection terminal to receive the resistance value output signal corresponding to a measured temperature from the temperature sensor of the probe.