Direction Indicator LED Current Regulation via Adaptive Resistance
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Solution Overview
Problem
Direction indicating apparatuses using LED elements face issues with varying power supply voltages, leading to inconsistent brightness between direction indicating and hazard operations, as the current through LED elements changes significantly, potentially causing damage or dimming.
Innovation Solution
A direction indicating apparatus with a pulse signal generating part, a variable resistor circuit, and a lighting status detecting part that adjusts resistance to maintain constant current through LED elements, using a P-type MOS transistor to switch resistance between two levels, ensuring consistent brightness during both operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a constant current circuit is provided to maintain constant brightness, then LED element service life is extended and brightness is kept constant, but the current flowing through each LED element decreases to approximately half in hazard operation, causing the LED element to darken
Solution Approach 1:
The patent applies dynamics by making the resistance value changeable based on operational mode. The resistance switching circuit dynamically adjusts between a first resistance value (for direction indicating operation) and a second resistance value (for hazard operation) to maintain appropriate current levels in each mode, thereby resolving the contradiction between constant current protection and sufficient brightness in hazard operation
Solution Approach 2:
The patent changes the electrical parameter (resistance) of the resistance switching circuit based on the operational state. By switching between different resistance values, the circuit adjusts the current distribution to LED elements, ensuring proper current limiting in normal operation while providing sufficient current in hazard operation to maintain brightness
2Reliability
If current is regulated for low power supply voltages, then LED element is protected from damage, but high power supply voltage causes current to increase and damage the LED element
Solution Approach 1:
The patent implements feedback by using the resistance switching circuit to respond to power supply voltage conditions and operational mode. The circuit monitors the state (direction indicating vs hazard operation) and adjusts resistance accordingly, providing automatic current regulation that protects against both low and high voltage conditions without requiring external voltage sensing
3Reliability
If current is regulated for high power supply voltages, then LED element is protected from overheating, but low power supply voltage causes current to decrease, leading to darkening or turning off of the LED element
Solution Approach 1:
The patent applies dynamics by making the resistance value adaptive to operational requirements. The resistance switching circuit dynamically selects between two resistance values based on whether the system is in direction indicating mode or hazard mode, ensuring optimal current levels for both protection and brightness requirements across different operating conditions
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 apparatus maintains consistent current and brightness across varying power supply voltages, reducing the difference in LED element current and brightness between direction indicating and hazard operations, thereby extending the LED element's service life and maintaining constant brightness.
Implementation Method 1
using a P-type MOS transistor to switch resistance between two levels
Data Source
AI summary
To provide a direction indicating apparatus that is less susceptible to a change of a power supply voltage and can reduce the difference in brightness of a direction indicating lamp using an LED element between a direction indicating operation and a hazard operation. A direction indicating apparatus includes a pulse signal generating part, a first switching element, a variable resistor circuit, a direction indicating switch, a hazard switch, first and second direction indicating lamps, a voltage detecting part and a lighting status detecting part.