Electrochromic Film Solid-State Imaging Pixel Dynamic Range
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Solution Overview
Problem
Existing solid-state imaging elements, such as CCD and CMOS image sensors, face limitations in extending dynamic range due to saturation of electric charge accumulation, leading to insufficient gray scale and unnatural image generation, particularly when strong light is incident.
Innovation Solution
A solid-state imaging element is designed with a unit pixel configuration that includes a photoelectric conversion element, an accumulation portion, and an electrochromic film with optical characteristics changing according to applied voltage, along with transfer, amplification, and selection transistors, allowing for automatic extension of dynamic range by adjusting light transmittance and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the accumulation portion accumulates electric charge from photoelectric conversion, then the incident light is converted into electric charge and stored, but the accumulation portion becomes saturated with electric charge when strong light is incident, resulting in insufficient gray scale
Solution Approach 1:
The patent applies the dynamics principle by making the light transmittance of the electrochromic film variable through voltage control. The film transitions from a first transmittance state to a second transmittance state based on applied voltage, enabling dynamic adjustment of light intensity reaching the photoelectric conversion unit. This dynamic control prevents charge accumulation saturation while maintaining measurement precision across varying light conditions.
Solution Approach 2:
The patent implements parameter changes by modifying the optical characteristics (light transmittance) of the electrochromic film through voltage application. By changing the transmittance parameter from a first value to a second value, the system adjusts the amount of light incident on the photoelectric conversion unit, thereby controlling the electric charge accumulation level and preventing saturation while preserving gray scale information.
2Adaptability or versatility
If an electrochromic film is formed on the semiconductor substrate to extend dynamic range, then light transmittance can be adjusted, but power consumption may increase and unnatural images may be generated
Solution Approach 1:
The patent applies preliminary action by pre-positioning the electrochromic film on the semiconductor substrate in the optical path before image capture. The film is configured to receive voltage signals and adjust its transmittance in advance or in real-time during the imaging process, enabling dynamic range extension without requiring additional processing steps that would increase power consumption.
Solution Approach 2:
The electrochromic film serves as an intermediary element between the incident light and the photoelectric conversion unit. By positioning the film in the optical path and controlling its transmittance through voltage application, the system mediates the light intensity reaching the sensor, extending dynamic range while avoiding direct modification of the photoelectric conversion process that would consume additional power.
3Adaptability or versatility
If the electrochromic film adjusts light transmittance to prevent saturation, then dynamic range is extended, but the structure and device complexity increase
Solution Approach 1:
The patent implements universality by integrating the electrochromic film directly onto the semiconductor substrate, making the same component serve multiple functions: it acts as both the substrate for the imaging element and the variable transmittance control element. This multi-functionality extends dynamic range without requiring separate additional structures, thereby limiting the increase in device complexity.
Solution Approach 2:
The patent applies the nested doll principle by embedding the electrochromic film within the existing semiconductor substrate structure. The film is formed on the substrate in the optical path, nesting the transmittance control function within the imaging element itself. This integration approach extends dynamic range while minimizing structural complexity by utilizing the existing substrate as the foundation for the additional functionality.
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
The solution enables automatic extension of dynamic range for each unit pixel, preventing saturation and maintaining sensitivity across varying light conditions without increasing power consumption or chip area, thereby improving image quality.
Implementation Method 1
an electrochromic film that has an optical characteristic changing according to applied voltage
Implementation Method 2
light incident on a sensor unit during a certain exposure time period is photoelectrically converted by a photodiode
Data Source
AI summary
Provided is a solid-state imaging element configured to automatically extend dynamic range for each unit pixel. A solid-state imaging element includes, for a unit pixel, a first photoelectric conversion element, a first accumulation portion that accumulates electric charge obtained by photoelectric conversion by the first photoelectric conversion element, and a first film that is electrically connected to the first accumulation portion and has an optical characteristic changing according to applied voltage. Furthermore, the unit pixel of the solid-state imaging element can further include a first transfer transistor that transfers electric charge obtained by photoelectric conversion by the photoelectric conversion element to the first accumulation portion, an amplification transistor that is electrically connected to the first accumulation portion, and a selection transistor that is electrically connected to the amplification transistor.