Projector Brightness Control via Distance Sensor
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Solution Overview
Problem
High-brightness projectors can cause eye fatigue or damage when projecting images onto small screens in low-light environments due to excessive brightness, as the perceived brightness is greater than the comfortable range for users.
Innovation Solution
A projector equipped with a distance sensor, light source, and brightness controlling circuit, where a processor calculates the image size and adjusts the luminous flux of the illumination beam to maintain a target brightness suitable for the user, using a lookup table to determine necessary adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high-brightness projector is used, then luminous flux is improved, but perceived brightness becomes excessive causing eye fatigue
Solution Approach 1:
The system dynamically changes the luminous flux parameter based on detected image size. When a small image size is detected, the processor automatically reduces the luminous flux to prevent excessive brightness. This parameter adjustment resolves the contradiction by adapting the luminous flux to match the actual viewing conditions, ensuring comfortable brightness levels while maintaining high luminous flux capability when needed.
2Power
If fixed high luminous flux is maintained, then projector performance is improved, but energy consumption increases
Solution Approach 1:
The system transitions from a static fixed luminous flux mode to a dynamic adaptive mode. The distance sensor continuously monitors image size, and the processor dynamically adjusts luminous flux in real-time based on these measurements. This dynamic operation allows the projector to consume only the necessary energy for the current viewing conditions, reducing overall energy consumption while maintaining optimal performance for each scenario.
Solution Approach 2:
The luminous flux parameter is changed from a fixed high value to a variable value that adapts to image size. The system maintains high projector performance by preserving the capability to output high luminous flux when large images are projected, while reducing energy consumption by lowering the luminous flux when small images are projected, thus optimizing the performance-energy tradeoff.
3Ease of operation
If automatic brightness adjustment is implemented, then user comfort is improved, but device complexity increases
Solution Approach 1:
The projector implements self-service brightness adjustment by automatically detecting image size through the distance sensor and autonomously adjusting luminous flux without user intervention. The processor serves itself by making intelligent decisions about the appropriate brightness level based on detected conditions, eliminating the need for manual user adjustment while improving comfort. This self-service approach adds minimal complexity compared to full manual control systems.
Solution Approach 2:
The system establishes a feedback loop where the distance sensor provides continuous information about image size to the processor, which then adjusts luminous flux accordingly. This feedback mechanism enables automatic brightness optimization while keeping the system relatively simple, as it uses basic sensor-input and processor-output components already present in modern projectors, adding only the necessary control logic.
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, a brightness controlling circuit, and a processor. The light source is configured to provide an illumination beam. The brightness controlling circuit is configured to control the light source. The processor calculates according to the distance to obtain an image size of a projected image on the projection plane and instructs the light source to adjust a luminous flux of the illumination beam according to the image size of the projected image for generating a target brightness value of the projected image. Here, the brightness of the projector is adjusted and maintained to allow users to comfortably watch images with proper brightness.