Light Emission Control Device Short-Circuit Detection
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Solution Overview
Problem
Existing light emission control devices cannot detect short-circuits in the first switching element used for PWM light control, as overcurrent detection methods fail to identify abnormalities in the switching element itself.
Innovation Solution
A light emission control device with a second detection circuit comparing the potential difference across a first resistor with a determination value, a logic determination circuit to assess the switching element's short-circuit status, and control signals to manage the switching elements' states, ensuring the detection of short-circuits and preventing further operation errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If overcurrent detection is performed on the light emitting element, then overcurrent abnormalities can be detected, but short-circuit defects in the first switching element cannot be detected
Solution Approach 1:
The detection function is segmented into two independent circuits: a first detection circuit that detects overcurrent abnormalities in the light emitting element, and a second detection circuit that detects short-circuit defects in the first switching element. This segmentation allows each circuit to specialize in detecting specific types of failures, resolving the contradiction between general overcurrent detection and specific short-circuit detection capabilities.
Solution Approach 2:
The first resistor serves as an intermediary element that converts the current state of the first switching element into a detectable voltage signal. By measuring the potential difference across this resistor, the second detection circuit can indirectly detect short-circuit conditions in the switching element without directly measuring current through the element itself.
2Ease of operation
If the first switching element is used for PWM light control, then brightness control is achieved, but the switching element may short-circuit and cause undetected failures
Solution Approach 1:
The second detection circuit continuously monitors the potential difference across the first resistor and provides feedback to the logic determination circuit. When a short-circuit condition is detected, the system can respond by stopping PWM light control operation, thereby maintaining reliability while preserving the brightness control capability during normal operation.
3Measurement precision
If the determination value is set high to avoid false detection, then short-circuit detection accuracy improves, but normal operation current may be misidentified as abnormal
Solution Approach 1:
The detection system applies different threshold criteria to different detection functions: the first detection circuit uses a threshold for overcurrent detection in the light emitting element, while the second detection circuit uses a separate determination value threshold for detecting short-circuit conditions in the switching element. This local differentiation of detection criteria resolves the contradiction between sensitivity and false 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
The solution effectively detects short-circuits in the first switching element, preventing incorrect operation and potential overheating, while distinguishing between overcurrent detection and short-circuit conditions, ensuring accurate control and safety in light emission management.
Implementation Method 1
a first potential difference that is a potential difference between both ends of the first resistor
Data Source
AI summary
A light emission control device controls a first switching element of a light source circuit including a first resistor, a light emitting element, and the first switching element coupled in series between a first power supply node and a second power supply node set to a lower potential than the first power supply node. The light emission control device includes a second detection circuit that compares a first potential difference between both ends of the first resistor with a determination value, a light emission control circuit that outputs a first control signal that controls on/off of the first switching element, and a logic determination circuit that determines whether or not the first switching element is short-circuited. The light emission control circuit sets the first control signal to a first drive stoppage state that inactivates the first control signal, and when the second detection circuit has detected that the first potential difference is larger than the determination value, the logic determination circuit outputs an error signal.