Vehicle Light Emitting Module Circuit for Negative Surge Protection
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Solution Overview
Problem
Existing light emitting modules face challenges in protecting light emitting elements from negative surges, suppressing voltage drops, and achieving miniaturization, particularly when using field effect transistors for protection.
Innovation Solution
A light emitting module incorporating a field effect transistor connected between the anode and cathode sides of the light emitting element, with a varistor in parallel to the field effect transistor, and additional protective elements like Zener diodes to manage voltage surges and reduce voltage drops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a diode is connected in series with multiple light emitting elements to protect against negative surge, then the light emitting element is protected, but the voltage drop becomes large and the total luminous flux cannot be achieved
Solution Approach 1:
The protection function is segmented between two components: the field effect transistor handles normal operation with minimal voltage drop, while the diode handles surge protection only when needed. This segmentation allows each component to optimize its function without the other's drawbacks.
Solution Approach 2:
The circuit dynamically switches between two protection modes: during normal operation, the field effect transistor conducts with low voltage drop; during negative surge, the diode becomes active to provide protection. This dynamic behavior resolves the contradiction between continuous protection and minimal energy loss.
2Loss of energy
If a field effect transistor is used to protect the light emitting element against negative surge and reduce voltage drop, then the voltage drop is suppressed, but the transistor becomes large in size and miniaturization is difficult
Solution Approach 1:
The protection function is segmented between two components: the field effect transistor handles normal operation with minimal voltage drop, while the diode handles surge protection only when needed. This segmentation allows each component to optimize its function without the other's drawbacks.
Solution Approach 2:
The diode is used as a sacrificial protection element that only activates during abnormal surge conditions. It accepts the voltage stress and potential damage in place of more expensive and larger alternative protection devices, enabling miniaturization of the overall system.
3Illumination intensity
If multiple light emitting elements are connected in series to achieve high luminous flux, then the total luminous flux increases, but the voltage drop increases and the desired luminous flux cannot be obtained
Solution Approach 1:
The circuit dynamically switches between two protection modes: during normal operation, the field effect transistor conducts with low voltage drop; during negative surge, the diode becomes active to provide protection. This dynamic behavior resolves the contradiction between continuous protection and minimal energy loss.
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 protects light emitting elements from surges, suppresses voltage drops, and enables miniaturization of the module, ensuring consistent luminous flux and reliability.
Implementation Method 1
a varistor which suppresses a voltage surge
Implementation Method 2
a field effect transistor having a source electrode, a drain electrode, and a gate electrode
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A light emitting module (20a), a vehicle lighting device, and a vehicle lamp are capable of achieving protection of a light emitting element (22) against a negative surge, suppression of a voltage drop, and miniaturization. The light emitting module (20a) includes: at least one light emitting element (22); a field effect transistor (25d1) electrically connected between an anode side and a cathode side of the light emitting element (22) and a DC power supply; and a varistor (25d2) connected in parallel with the field effect transistor (25d1).