Projector Brightness Control via Distance Sensor and Luminous Flux Adjustment
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Solution Overview
Problem
Existing projectors fail to automatically adjust their brightness to comply with the Society of Motion Picture and Television Engineers (SMPTE) standards, leading to excessive brightness that causes eye fatigue and discomfort, and they lack mechanisms to maintain brightness and color over time due to brightness decay and color distortion.
Innovation Solution
A projector system equipped with a distance sensor, light source, and brightness controlling circuit, where a processor calculates the image size and adjusts the luminous flux to achieve the target brightness value, and includes a method for current compensation after brightness decay to maintain optimal brightness and color.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high brightness projector is used, then luminous flux is improved, but projected image brightness becomes excessive causing eye fatigue
Solution Approach 1:
The patent implements dynamic brightness adjustment by detecting projection screen size and automatically adjusting the light source current accordingly. The system transitions from static high brightness output to dynamic adaptive brightness control, where the brightness level changes based on real-time detection of projection conditions.
Solution Approach 2:
The patent changes the operating parameters of the light source by adjusting current levels based on projection screen size. Different current parameters are applied to achieve appropriate brightness levels - higher currents for large screens and lower currents for small screens, thereby resolving the contradiction between luminous flux and projected image brightness.
2Power
If fixed high current is applied to light source, then luminous flux is maintained, but brightness decay and color distortion occur over time
Solution Approach 1:
The patent incorporates a brightness decay compensation mechanism that proactively adjusts light source current to compensate for anticipated brightness decay. The system pre-calibrates compensation values and applies them to maintain consistent brightness output over time, preventing the harmful effects of brightness decay and color distortion before they occur.
3Object-affected harmful factors
If projector brightness is reduced to meet SMPTE standards, then eye comfort is improved, but luminous flux decreases
Solution Approach 1:
The patent applies local quality adjustment by tailoring the brightness output specifically to match the projection screen size. Instead of uniformly reducing brightness across all conditions, the system provides locally optimized brightness levels - higher for large screens and lower for small screens - thereby maintaining adequate luminous flux while ensuring eye comfort for each specific application.
Data Source
AI summary
A projector and a brightness adjusting method are provided. The projector includes a distance sensor configured to detect a distance between the projector and a projection plane, a light source configured to provide an illumination beam, a brightness controlling circuit configured to control the light source, and a processor coupled to the distance sensor, the light source, and the brightness controlling circuit. The processor calculates according to the distance to obtain an image size of a projected image on the projection plane. The processor obtains a current value corresponding to the image size according to a color table. The processor instructs the light source to adjust a luminous flux of the illumination beam according to the current value for generating a target brightness value of the projected image. When a brightness of the projected image is excessively large, a brightness of an image beam of the projector is automatically reduced.