Imaging Pixel Layout With Reflection Unit for Diffraction Suppression
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Solution Overview
Problem
The challenge is to reduce the size of imaging devices while minimizing light diffraction to the optical black region, which is typically achieved by reducing the ineffective pixel region without increasing noise or chip size.
Innovation Solution
Incorporating a reflection unit in the ineffective pixel region of the semiconductor substrate, which reflects incident light and suppresses diffraction to the light-shielding pixel region, allowing for a reduction in the ineffective pixel area and thus a smaller chip size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the ineffective pixel region is reduced to decrease chip size, then chip size is reduced, but light diffraction to the light-shielding pixel region increases causing noise increase
Solution Approach 1:
A reflection unit is introduced as an intermediary component in the ineffective pixel region between effective pixels and light-shielding pixels. This reflection unit reflects incident light back toward the effective pixel region, preventing light diffraction from reaching the light-shielding pixel region and causing noise. The reflection unit acts as a mediator that redirects light paths to achieve both chip size reduction and noise suppression.
Solution Approach 2:
The invention converts the potentially harmful light diffraction phenomenon into a beneficial effect by using the reflection unit to redirect diffracted light back toward the effective pixel region. Instead of allowing diffraction to cause noise in the light-shielding region, the reflection unit captures this diffracted light and redirects it to contribute to the imaging function, thereby converting a harmful effect into a useful one.
2Productivity
If the ineffective pixel region is reduced to improve productivity, then chip size and manufacturing cost are reduced, but light diffraction increases affecting measurement precision
Solution Approach 1:
The reflection unit serves as an intermediary that maintains measurement precision by preventing light diffraction from reaching light-shielding pixels. This allows the ineffective pixel region to be minimized for manufacturing efficiency while the reflection unit ensures that no spurious light reaches the light-shielding region, thereby preserving pixel signal accuracy for precise measurements.
3Area of moving object
If the ineffective pixel region is minimized to reduce chip area, then device compactness is improved, but light diffraction to optical black region increases
Solution Approach 1:
The reflection unit is positioned in the minimized ineffective pixel region as an intermediary to capture and redirect light that would otherwise diffract into the light-shielding pixel region. By placing this reflection unit within the compact ineffective region, the invention achieves both device compactness and suppression of harmful diffraction light.
Solution Approach 2:
The reflection unit converts the harmful diffraction light generated by the minimized ineffective pixel region into a beneficial effect by redirecting it back toward the effective pixel region. This allows the ineffective region to be minimized for compactness while the reflected light contributes positively to the imaging function rather than causing noise.
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 configuration effectively reduces the chip size by minimizing light diffraction to the light-shielding pixel region, improving image quality and noise suppression, while maintaining accurate pixel signal correction.
Implementation Method 1
a reflection unit provided on the incident surface side of the semiconductor layer that reflects the light
Implementation Method 2
suppress diffraction of light to an optical black region
Data Source
AI summary
Provided are an imaging device and a ranging device capable of reducing a chip size while suppressing diffraction of light to a light-shielding pixel region. The imaging device includes a semiconductor layer including an incident surface on which light is incident, a plurality of pixels provided on the semiconductor layer and arranged in parallel to the incident surface, and a reflection unit provided on the incident surface side of the semiconductor layer that reflects the light. The plurality of pixels includes a plurality of effective pixels that photoelectrically converts the light to generate a pixel signal and outputs the generated pixel signal to an AD conversion circuit that converts a digital signal to an analog signal, a plurality of light-shielding pixels the incident surface side of which is covered with a light-shielding film, and a plurality of ineffective pixels provided between the plurality of effective pixels and the plurality of light-shielding pixels and not connected to the AD conversion circuit. The reflection unit is arranged in an ineffective pixel region in which the plurality of ineffective pixels is arranged in the semiconductor substrate.