Light-Sensing LED Drive Circuit for Self-Illumination Isolation
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Solution Overview
Problem
Conventional light sensing lamps using visible light are easily affected by self-luminescence and suffer from poor circuit reliability due to large inrush currents.
Innovation Solution
A light sensing drive circuit comprising a filtering and rectifying module, a power module, a light sensing module, a sampling module, a main control module, and a drive module, which includes an optoelectronic isolator and a MOS transistor to eliminate self-illumination effects and manage inrush currents by adjusting the driving voltage based on ambient light conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a MOS transistor is connected in series at the output light source to control light sensing, then the lamp can be controlled to turn on/off based on ambient light, but large inrush current occurs when the MOS transistor turns on, reducing circuit reliability
Solution Approach 1:
The patent applies preliminary action by using a sampling module to detect the voltage waveform of the rectified voltage in advance before the MOS transistor turns on. The main control module generates a control signal with a preset duty cycle based on this sampling, ensuring that the MOS transistor is turned on at the appropriate timing point of the rectified voltage waveform. This preliminary detection and timing control prevents large inrush current by avoiding turn-on at voltage peaks, thereby improving circuit reliability while maintaining light sensing control functionality.
2Productivity
If visible light sensing is used to detect ambient light, then the lamp responds to ambient light changes, but self-illumination from LED modules interferes with accurate light intensity detection
Solution Approach 1:
The patent applies the taking out principle by separating the light detection function from the LED light emission function in time. The control method ensures that light intensity detection is performed during periods when the LED modules are not emitting light or at moments when self-illumination does not interfere with the photosensitive sensor. This temporal separation extracts the accurate light sensing capability from the interference of self-illumination, allowing the lamp to respond to ambient light changes while maintaining detection accuracy.
3Speed
If the MOS transistor is turned on immediately when ambient light decreases, then the lamp turns on quickly, but large inrush current damages the circuit
Solution Approach 1:
The patent applies preliminary action by implementing a sampling module that detects the voltage waveform of the rectified voltage before the MOS transistor is turned on. The main control module uses this sampling information to generate a control signal with a preset duty cycle, timing the MOS transistor turn-on event to occur at an appropriate point in the rectified voltage waveform cycle. This preliminary detection and timing control enables the lamp to respond quickly to ambient light changes while avoiding large inrush current by preventing turn-on at voltage peaks, thus maintaining both fast response speed and circuit reliability.
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 eliminates the impact of self-illumination on ambient light detection and improves circuit reliability by preventing large inrush currents, ensuring accurate light intensity detection and stable operation.
Implementation Method 1
The switch module includes an optoelectronic isolator and a MOS transistor. An anode of an illuminator of the optoelectronic isolator is an input end of the switch module for inputting a control signal
Implementation Method 2
The light sensing module is configured to connect with the power module, and to detect ambient light intensity to generate a light sensing signal
Data Source
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AI summary
The present application pertains to the technical field of illumination, and a light sensing drive circuit and a lamp are provided. The light sensing drive circuit, connected with an LED module, includes a filtering and rectifying module, a power module, a light sensing module, a sampling module, a main control module, and a drive module. The filtering and rectifying module is configured to generate a rectified voltage according to the commercial power; the power module is configured to generate a supply voltage according to the rectified voltage; the light sensing module is configured to generate a light sensing signal according to ambient light intensity and the supply voltage; the sampling module is configured to generate a sampling signal according to the rectified voltage; the main control module is configured to generate a control signal of a preset duty cycle according to the light sensing signal and the sampling signal when the drive module is turned off by the control signal; the drive module is configured to generate a driving voltage according to the control signal and the rectified voltage so as to drive the internal LED module to emit light.