Lighting Circuit Control for Synchronized LED Group Switching
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Solution Overview
Problem
Conventional lighting devices with light emitting element groups connected in parallel to a power supply circuit experience variations in turn-on and turn-off timings due to differing light emission reference voltages, leading to impaired visibility and potential safety hazards, especially in in-vehicle exterior lamps.
Innovation Solution
A lighting device that includes a power supply circuit, light emitting element groups with different light emission reference voltages, and a light emission control unit comprising a comparing circuit and a transistor. The light emission control unit detects the drive voltage and light emission reference voltage, controlling the light emission of the light emitting element groups to ensure simultaneous and synchronized light emission without variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple light emitting element groups with different light emission reference voltages are connected in parallel to a power supply circuit, then the lighting device can provide diversified design and flexible configuration, but the turn-on and turn-off timings of the light emitting elements will vary, causing impaired fine view and woolly lighting
Solution Approach 1:
The patent applies preliminary action by introducing a capacitor connected in parallel to each light emitting element group. This capacitor is pre-charged during the voltage rise phase and pre-discharged during the voltage fall phase, ensuring that all light emitting element groups turn on and off simultaneously despite having different reference voltages. The capacitor acts in advance to compensate for voltage variations before they affect the light emission timing.
2Adaptability or versatility
If light emitting element groups with different light emission reference voltages are used, then flexible configuration is achieved, but variation in turn-on and turn-off timings occurs, leading to safety hazards in in-vehicle exterior lamps
Solution Approach 1:
The capacitor is pre-charged to a voltage higher than the light emission reference voltage before the light emitting element group needs to turn on. During voltage rise, the capacitor charges up and then discharges to maintain the voltage above the reference level, ensuring simultaneous turn-on. During voltage fall, the capacitor charges from the power supply and then discharges to keep the voltage above the reference level, ensuring simultaneous turn-off. This preliminary charging and discharging action prevents woolly lighting.
Data Source
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AI summary
A lighting device includes light emitting element groups (HSB) including a light emitting element group (HS2) that emits light when being applied with a voltage at a light emission reference voltage (VH2), and a light emitting element group (HS12) that emits light when being applied with a light emission reference voltage (VH12) higher than the light emission reference voltage (VH2), the light emitting element groups (HSB) emitting light when being applied with a voltage equal to or higher than a light emission reference voltage (VHa); a semiconductor chip (IC1) including a light emission control unit (HC1) arranged to perform light emission control to cause light emission of a light emitting element group (HS) if a drive voltage (Vk) is higher than the light emission reference voltage (VHa), and to perform light emission stop control to stop the light emission if the drive voltage (Vk) is lower than the same; and a semiconductor chip (IC2) including a light emission control unit (HC2) arranged to perform light emission control to cause light emission of a light emitting element group (HSa) if the drive voltage (Vk) is higher than the light emission reference voltage (VHa), and to perform light emission stop control to turn off the emitting element group (HSa) if the drive voltage (Vk) is lower than the same.