Vehicle Camera Heater Circuit for Rapid Defrosting
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Solution Overview
Problem
Existing vehicle imaging apparatuses with heaters experience slow temperature increase due to the use of negative temperature coefficient (NTC) thermistors, which limit the effectiveness of frost and water droplet removal.
Innovation Solution
Incorporating a transparent heater and a resistance member with increasing electrical resistance value as temperature rises, allowing for a higher initial current flow to quickly increase the heater's temperature, and using a heat transfer suppression unit to manage heat distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If an NTC thermistor is used as a temperature sensor in the heater circuit, then temperature detection is achieved, but the initial current flow is limited due to high resistance, resulting in slow heater temperature increase
Solution Approach 1:
The patent changes the resistance characteristic from NTC (negative temperature coefficient) to PTC (positive temperature coefficient). The PTC thermistor exhibits low resistance at startup temperatures, allowing high initial current flow to rapidly heat the heater. As the PTC thermistor temperature increases, its resistance increases automatically, reducing current and preventing overheating. This parameter change resolves the contradiction by enabling both rapid initial heating and automatic temperature control.
2Productivity
If high current is applied to the heater at startup, then rapid temperature increase is achieved, but excessive heating and energy waste occur
Solution Approach 1:
The PTC thermistor provides automatic feedback control through its inherent positive temperature coefficient characteristic. As the heater and PTC thermistor temperature rise, the increasing resistance automatically reduces the current flow, creating a self-regulating system. This feedback mechanism ensures rapid initial heating when needed while automatically preventing excessive heating and energy waste as the target temperature is approached.
3Reliability
If the heater temperature is rapidly increased to remove frost and water droplets, then defrosting effectiveness is improved, but control precision becomes difficult to maintain
Solution Approach 1:
The PTC thermistor enables the heater system to serve itself through automatic temperature regulation. The inherent PTC characteristic causes the resistance to increase with temperature, automatically reducing current and preventing overheating without external control. This self-service mechanism maintains precise temperature control while ensuring reliable defrosting performance, as the system naturally transitions from high-power startup to stable operating temperature.
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 configuration enables rapid temperature increase of the heater, effectively evaporating frost and water droplets, while suppressing excessive heating and providing flexibility in the resistance member's placement.
Implementation Method 1
a transparent heater provided at least in a range of an angle of view of the imaging device at the imaging side of the imaging device, generating heat by being energized, and heating the imaging side of the imaging device
Implementation Method 2
a resistance member provided at an electrical circuit that includes the heater, and generating heat by being energized, an electrical resistance value of the resistance member being increased along with increase in temperature of the resistance member due to heat generation
Data Source
AI summary
A vehicle imaging apparatus includes an imaging device capable of imaging an imaging side thereof; a transparent heater that is provided at least in a range of an angle of view of the imaging device at the imaging side of the imaging device, that generates heat by being energized, and that heats an imaging side of the imaging device; and a resistance member that is provided at an electrical circuit including the heater, and that generates heat by being energized, an electrical resistance value of the resistance member is increased along with increase in temperature of the resistance member due to heat generation such that a current value of current that flows to the heater is decreased.