LED Direction Indicator Failure Detection via Series Circuit Current Measurement
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Solution Overview
Problem
Existing directional indicator systems for straddle type vehicles, such as those described in JP 2004-9825 A, are inadequate in detecting failures in LEDs due to measuring total current, which makes it difficult to determine the number of failed LEDs and the resulting light emission, especially under voltage decreases like battery deterioration or failure.
Innovation Solution
The system employs LED series circuits connected in parallel, with current measurement and detection mechanisms to accurately identify failures in individual LED series circuits, allowing for precise detection of breaks or short circuits and adjusting the blink rate or turning off indicators as necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If total current measurement is used to detect LED failures, then the detection mechanism is simple, but the failure detection accuracy deteriorates because it cannot determine the number of failed LEDs or assess sufficient light emission
Solution Approach 1:
The patent divides the LED array into multiple independently controllable groups (e.g., first LED array, second LED array, third LED array) with separate drive circuits. Each group can be tested individually by applying test signals and measuring current, allowing precise identification of which specific LEDs or groups have failed without requiring complex per-LED measurement infrastructure.
2Use of energy by moving object
If voltage applied to directional indicator decreases due to battery deterioration or failure, then energy consumption is reduced, but the ability to detect LED failures deteriorates because changes in current when LEDs fail become too small to detect
Solution Approach 1:
The patent performs failure detection at multiple predetermined timings: when the vehicle starts, when the ignition switch is turned on, and periodically during operation. By conducting tests in advance and at regular intervals rather than continuously, the system maintains high detection sensitivity while minimizing energy consumption during normal operation.
Solution Approach 2:
The failure detection is implemented as periodic intermittent operation rather than continuous monitoring. The control unit activates test signals at predetermined intervals to check LED functionality, which reduces overall energy consumption while ensuring failures are detected promptly. This periodic testing approach balances detection sensitivity requirements with energy conservation.
3Measurement precision
If individual LED current measurement is implemented for each LED series circuit, then failure detection accuracy improves, but device complexity increases
Solution Approach 1:
The patent employs a universal test signal generation mechanism and current measurement system that can be applied to multiple LED groups sequentially. The same drive circuit and measurement infrastructure are reused across different LED arrays through time-multiplexed testing, avoiding the need for dedicated per-LED measurement hardware and reducing overall system complexity while maintaining accurate failure detection.
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 approach enables correct detection of LED failures, ensuring sufficient light emission and proper operation of directional indicators even under voltage decreases, improving reliability and accuracy in failure detection.
Implementation Method 1
each LED driver circuit (56a, 57a) having a function of measuring a value of current flowing through a corresponding one of the plurality of LED series circuits (35)
Data Source
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AI summary
A directional indicator system (50) includes a front directional indicator (30) and a driver (51) for controlling driving of the front directional indicator (30). The front directional indicator (30) includes a plurality of LED series circuits (35), each LED series circuit having a plurality of LEDs (33) connected in series. The plurality of LED series circuits (35) are connected in parallel. The driver (51) includes a plurality of LED drivers (56a and 57a) each for driving a corresponding one of the plurality of LED series circuits (35) and a plurality of current detectors (56b and 57b) each for measuring the value of current in a corresponding one of the plurality of LED series circuits (35).