Vehicle Lighting Device Current Control Circuit
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Vehicle lighting devices that use light emitting diodes struggle to effectively control current in response to changes in input power supply voltage and ambient temperature, leading to potential circuit or diode damage.
Innovation Solution
A vehicle lighting device configuration that includes current control circuits to adjust the voltage dividing resistor current based on input power supply voltage and ambient temperature changes, using differential circuits and current mirror circuits to manage current supply to the light emitting element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a voltage dividing resistor is used to control current in response to input power supply voltage changes, then current control capability is improved, but the device cannot respond to temperature changes
Solution Approach 1:
The voltage dividing resistor is designed to serve dual functions: it divides voltage for current control in response to input power supply voltage changes, and simultaneously acts as a temperature detection element whose resistance changes with temperature. This allows a single component to provide both voltage division and temperature sensing capabilities, resolving the contradiction between current control reliability and adaptability to temperature changes.
Solution Approach 2:
The patent merges the voltage dividing function and temperature detection function into a single voltage dividing resistor. By combining these two functions that were previously performed by separate components, the system achieves both voltage-based current control and temperature-based current control without increasing device complexity.
2Adaptability or versatility
If a thermistor is used as voltage dividing resistor for temperature compensation, then temperature response capability is improved, but power consumption increases
Solution Approach 1:
The voltage dividing resistor utilizes its own temperature-dependent resistance characteristics to detect temperature changes and provide feedback for current control. The resistor serves itself as both the voltage dividing element and the temperature sensor, eliminating the need for separate active temperature sensing components that would increase power consumption.
Solution Approach 2:
The voltage dividing resistor acts as an intermediary element that translates temperature changes into resistance changes, which then affect the voltage division ratio and subsequently the current supplied to the light emitting element. This passive intermediary approach avoids the need for active temperature sensing and processing circuits that would consume additional power.
3Illumination intensity
If current is increased to compensate for temperature rise, then light output stability is improved, but risk of circuit damage increases
Solution Approach 1:
The system employs feedback control where the voltage dividing resistor continuously monitors temperature changes and automatically adjusts the current supplied to the light emitting element accordingly. When temperature rises, the resistor's resistance changes, which feeds back to the control circuit to reduce current, preventing overheating and circuit damage while maintaining stable light output.
Solution Approach 2:
The voltage dividing resistor provides preliminary protective action by preemptively adjusting current levels in response to temperature changes before damage can occur. The temperature-dependent resistance changes trigger current reduction in advance, preventing the light emitting element and circuit from reaching dangerous temperature levels.
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 controlled current supply to the light emitting element, ensuring safe operation and low power consumption in response to voltage changes and temperature variations.
Implementation Method 1
a voltage dividing resistor made of a thermistor that is connected between a constant voltage source and a ground terminal
Implementation Method 2
A light emitting element such as a light emitting diode has a feature that a luminous intensity of light changes depending on a value of a current that is supplied thereto
Data Source
AI summary
A vehicle lighting device according to the present invention is configured in such a manner that a current that is supplied to a light emitting element that serves as a light source can be controlled with low power consumption in accordance with either of a voltage change in input power supply and a change in ambient temperature. This vehicle lighting device is configured in such a manner as to take out a reference voltage that is input to a switching controller 5 from a voltage dividing resistor R2 that is connected between a constant voltage source Vcc and a ground terminal GND. A current control circuit 10C for voltage change is provided to between an input power supply Vin and the ground terminal GND. Further, a current control circuit 10A for temperature change is provided to between the constant voltage source Vcc and the ground terminal GND.