Projection Light-Source Driving Circuit for Light-Load Flicker Control
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Solution Overview
Problem
Projection devices experience flickering of the projection image due to discontinuous waveforms in the driving current when they enter a light-load state, causing the light source to receive a lower current output.
Innovation Solution
A driving circuit comprising a power converter, a detection circuit, and a control circuit is used to detect the light-load state and adjust the driving power by decreasing the current value and increasing the switching frequency, preventing the generation of negative current values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the projection device enters a light-load state and supplies lower current to the light source, then energy consumption is reduced, but the light source produces flickering due to discontinuous waveform
Solution Approach 1:
The patent applies dynamics by making the driving current waveform adaptive to load conditions. The control circuit dynamically adjusts the waveform characteristics based on whether the system is in light-load or medium/heavy-load state, transforming the static driving approach into a dynamic one that responds to real-time conditions, thereby resolving the contradiction between energy saving and image stability
Solution Approach 2:
The patent changes the parameter of current waveform shape based on load state. In light-load state, it uses a first waveform that prevents flickering, while in medium/heavy-load state, it uses a second waveform optimized for efficiency. This parameter change approach allows the system to optimize both energy consumption and image stability under different operating conditions
2Power
If the driving current is reduced in light-load state, then power consumption decreases, but the current waveform becomes discontinuous causing flickering
Solution Approach 1:
The control circuit dynamically switches between different current waveform patterns based on the detected load state. When power is reduced in light-load state, the system transitions to a first waveform pattern that maintains continuity, preventing flickering while still achieving power reduction. This dynamic adaptation resolves the contradiction between power reduction and waveform continuity
Solution Approach 2:
The patent implements feedback control where the control circuit monitors the load state and adjusts the current waveform accordingly. The feedback mechanism ensures that when power is reduced, the waveform characteristics are automatically adjusted to maintain stability, preventing the discontinuity that would cause flickering while achieving the desired power reduction
3Productivity
If a non-constant sawtooth wave driving current is used, then the power converter operates efficiently, but the light source flickers under light-load conditions
Solution Approach 1:
The patent makes the driving waveform dynamic rather than static. The control circuit selects between a first waveform pattern (for light-load state with light source stability) and a second waveform pattern (for medium/heavy-load state with high conversion efficiency). This dynamic waveform selection resolves the contradiction by adapting the waveform characteristics to match the operational requirements of each load state
Solution Approach 2:
The patent changes the waveform parameters based on load conditions. In light-load state, it uses a first waveform pattern that prioritizes light source stability, while in medium/heavy-load state, it uses a second waveform pattern that optimizes conversion efficiency. This parameter change strategy allows the system to achieve both high productivity and reliability under different operating conditions
Data Source
AI summary
A driving circuit for driving a light source and a projection device are provided. The driving circuit includes a power converter, a detection circuit, and a control circuit. The power converter provides a driving power to the light source. The detection circuit provides a feedback signal according to a current value of the light source. The control circuit receives an operation command and the feedback signal. The control circuit determines whether the driving circuit enters a light-load state according to at least one of the operation command and the feedback signal. When the driving circuit is determined to enter the light-load state, the control circuit controls the power converter to decrease a current value of the driving power and controls the power converter to increase a switching frequency of the driving power. The driving circuit and the projection device may prevent the light source from flickering under the light-load state.