Light Source Control Device for Projector Scroll Noise Reduction
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Solution Overview
Problem
Existing light source control systems for projectors face challenges in preventing scroll noise, which occurs due to interference between flickers from solid-state light sources and light modulation devices, requiring frequent reconfiguration of blinking periods when different light modulation devices are used.
Innovation Solution
A light source control device that determines a duty ratio for solid-state light sources based on target light intensity and generates control signals with phased differences between light sources, reducing flicker interference and scroll noise without being affected by the characteristics of the light modulation device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the blinking period of the solid-state light source is varied to prevent scroll noise, then scroll noise is eliminated, but the control frequency becomes closely associated with the light modulation device characteristics, requiring reconfiguration when devices are changed
Solution Approach 1:
The patent divides the solid-state light source into multiple independent light sources (first, second, third, and fourth light sources). Each light source is controlled separately with different duty ratios, allowing the system to prevent scroll noise through differential control without requiring global reconfiguration when light modulation devices are changed.
Solution Approach 2:
Different duty ratios are applied to different light sources based on their specific characteristics and the target light intensity requirements. The determination section calculates optimal duty ratios for each light source individually, enabling localized optimization that prevents scroll noise while maintaining adaptability to various light modulation devices.
2Use of energy by moving object
If PWM control is used for solid-state light sources, then power consumption is reduced and control efficiency is improved, but flicker interference occurs that can generate visually recognizable scroll noise
Solution Approach 1:
The patent uses PWM control with specific duty ratios applied periodically to multiple light sources. By controlling the emission and extinction periods of each light source with different duty ratios, the system maintains the energy efficiency of PWM control while preventing the buildup of periodic flicker interference that causes scroll noise.
Solution Approach 2:
Different duty ratios are assigned to different light sources, creating asymmetric control patterns. This asymmetry in the PWM control parameters prevents the synchronous flicker that would otherwise occur with uniform control, thereby eliminating scroll noise while preserving the power efficiency benefits of PWM control.
Data Source
AI summary
A light source control device and a light source control method each capable of preventing the scroll noise from occurring without being affected by the characteristics of a light modulation device, and a projector equipped with the light source control device are provided. The light source device includes a duty determination section adapted to determine a duty ratio, and a drive control section adapted to perform drive control of a plurality of solid-state light sources by generating a PWM signal having the duty ratio determined by the duty ratio determination section, and adapted to make a phase with which at least one of the solid-state light sources is driven different from a phase with which another of the solid-state light sources is driven.