Integrated Infrared Band-Pass Filter for Thin Image Sensors
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Solution Overview
Problem
Conventional image sensors in compact camera modules, such as those in mobile phones, face challenges in thickness reduction due to the presence of thick glass substrates in infrared filter elements, which hinder the miniaturization of camera modules and reduce quantum efficiency.
Innovation Solution
Incorporating an infrared band-pass filter and corresponding photosensitive devices within the image sensor, allowing for the subtraction of infrared signals during post-processing, thus eliminating the need for a separate infrared filter element and reducing the module's thickness while enhancing quantum efficiency by increasing the amount of radiation entering the sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick glass substrate is used in the infrared filter element, then the infrared filtering function is effective, but the camera module thickness increases and quantum efficiency decreases
Solution Approach 1:
The patent extracts the infrared filtering function from the traditional separate infrared filter element (glass substrate) and integrates it into the image sensor structure itself. The infrared photosensitive device and its corresponding band-pass filter are built directly on the sensor substrate, removing the need for a thick external glass substrate while maintaining effective infrared filtering.
Solution Approach 2:
The patent merges the infrared filtering function with the image sensor structure by integrating the infrared band-pass filter and infrared photosensitive device directly onto the sensor substrate. This consolidation eliminates the separate infrared filter element and its thick glass substrate, reducing overall module thickness.
2Reliability
If a thick glass substrate is used in the infrared filter element, then the infrared filtering function is effective, but the quantum efficiency decreases due to reduced radiation entry
Solution Approach 1:
The patent removes the thick glass substrate that blocked radiation from entering the sensor. By extracting this obstructive element and replacing it with a integrated infrared filter structure, more radiation can reach the photosensitive devices, thereby improving quantum efficiency while maintaining infrared filtering capability.
3Length of stationary object
If the camera module is scaled down for compact design, then the mobile phone thickness is reduced, but the production of camera modules with desired thickness becomes more difficult
Solution Approach 1:
The patent combines multiple functions (infrared filtering, infrared sensing, and visible light sensing) into a single integrated image sensor structure. This merger reduces the number of separate components and assembly steps, making it easier to manufacture compact camera modules with controlled thickness while maintaining all necessary functions.
4Reliability
If a separate infrared filter element is used, then the infrared filtering is effective, but the device complexity increases
Solution Approach 1:
The patent merges the infrared filter element with the image sensor structure, eliminating the separate component. The infrared band-pass filter and photosensitive device are integrated directly on the sensor substrate, reducing the number of discrete parts and simplifying the overall device structure while maintaining effective infrared filtering.
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
This approach enables the thinning of camera modules, allowing for more compact designs while improving the quantum efficiency of image sensors by removing the glass substrate and allowing more radiation to enter, resulting in enhanced image capture capabilities.
Implementation Method 1
Each of the pixels includes an infrared band-pass filter and an infrared photosensitive device corresponding to the infrared band-pass filter
Implementation Method 2
the image sensor includes various pixels, and at least one of the pixels includes an infrared band-pass filter and an infrared photosensitive device corresponding to the infrared band-pass filter
Data Source
AI summary
An image sensor includes a substrate, dual-waveband photosensitive devices, at least one infrared photosensitive device, a transparent dielectric layer, at least one infrared band-pass filter, a color filter layer and a micro-lens layer. The dual-waveband photosensitive devices are disposed in the substrate, and each dual-waveband photosensitive device is configured to sense an infrared light and one visible light. The infrared photosensitive device is disposed in the substrate, in which the dual-waveband photosensitive devices and the infrared photosensitive device are arranged in an array. The transparent dielectric layer is disposed over the dual-waveband photosensitive devices and the infrared photosensitive device. The infrared band-pass filter is disposed in the transparent dielectric layer and corresponds to the infrared photosensitive device. The color filter layer is disposed to cover the transparent dielectric layer and the infrared band-pass filter. The micro-lens layer is disposed on the color filter layer.