Image Sensor Proximity Judgment via IR LED and Pass Filter
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Solution Overview
Problem
Conventional image sensors face challenges in implementing a proximity function without increasing bulk or production cost, as they require separate proximity sensors and mechanical IR cutoff filter adjustments, which hinder miniaturization and image quality in low-light environments.
Innovation Solution
An image sensor system incorporating an IR LED emitting a specific band of wavelengths and an IR pass filter that transmits only this band, allowing the sensor to measure changes in output voltage and judge proximity based on IR light reflection, thereby eliminating the need for separate proximity sensors and minimizing image degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a separate proximity sensor is installed to realize proximity function, then proximity sensing capability is improved, but device volume and production cost increase
Solution Approach 1:
The patent combines the proximity sensing function with the existing image sensor by using the IR LED and photodetector that are already present in the image sensor structure. The proximity sensor and image sensor share common components (IR LED, photodetector, lens), merging two functions into one integrated device, thereby avoiding volume increase while maintaining proximity sensing capability
Solution Approach 2:
The image sensor is designed to perform multiple functions: both image capture and proximity sensing. The IR LED serves dual purposes as both a lighting source for night photography and a proximity detection source. The photodetector array processes both image data and proximity information, making the device universal and eliminating the need for separate dedicated components
2Illumination intensity
If an IR cutoff filter is removed to enable IR light source usage in dark environments, then night photography capability is improved, but image quality degradation occurs due to IR light interference
Solution Approach 1:
The patent applies different filtering characteristics to different regions or functions within the sensor system. The IR pass filter is designed to transmit only specific IR wavelengths (matching the IR LED emission) while blocking other IR wavelengths that would degrade image quality. This localized spectral filtering allows night photography functionality while preventing image quality degradation from unwanted IR light
Solution Approach 2:
The patent changes the spectral transmission parameters of the filter system. Instead of using a traditional IR cutoff filter that blocks all IR light, an IR pass filter is introduced with specific transmission characteristics that allow only the desired IR wavelength band to pass through, thereby enabling night photography while maintaining image quality by blocking harmful IR wavelengths
3Adaptability or versatility
If a moving means is installed to adjust IR cutoff filter position according to external light source, then adaptability to lighting conditions is improved, but device bulk and production cost increase
Solution Approach 1:
The system automatically adapts to lighting conditions through electronic control rather than mechanical adjustment. The controller selectively activates the IR LED and adjusts the IR pass filter based on detected light levels, eliminating the need for moving means to physically reposition filters. The system serves itself by using electronic switching and control algorithms to adapt to different lighting environments
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
Enables accurate proximity judgment and minimizes image quality degradation by using the IR LED as both a light source for night photography and proximity sensing, reducing bulk and production costs while maintaining image quality.
Implementation Method 1
measuring a change in output voltage value of a sensor element caused by the IR light having a specific band of wavelengths of IR light that is radiated from the IR LED, is reflected from the subject, and is incident to the sensor element
Implementation Method 2
an IR pass filter, which is capable of transmitting visible light and the IR light having this specific band of wavelengths
Data Source
AI summary
An image sensor is capable of judging proximity to a subject. The image sensor judges the distance to the subject using a change in output voltage value by the presence or absence of a specific band of wavelengths of infrared (IR) measured by optical sensors such as proximity pixels. Thereby, the image sensor enables an ordinary image sensor to easily realize a proximity function, and makes it possible to minimize damage to a quality of image when the image is picked up in a night photography mode or in a proximity photography mode.