Imaging Element Dual Photodiode Charge Transfer for Ranging
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Solution Overview
Problem
Conventional imaging devices with three photodiodes per pixel have a complex configuration, making them difficult to simplify and efficiently perform ranging tasks, especially when measuring distances to flat subjects.
Innovation Solution
An imaging element with two photoelectric conversion units, two electric charge holding units, and specific electric charge transfer units that allow for individual and common transfer control of electric charges, enabling the generation of phase difference signals and image signals for both phase difference detection and time-of-flight ranging, thereby simplifying the pixel configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If three photodiodes are arranged for each pixel to enable both ToF and phase difference detection, then both ranging methods can be performed, but the configuration becomes complicated
Solution Approach 1:
The patent combines both ToF and phase difference detection functionalities into a single pixel structure using two photodiodes. The first photodiode detects light for ToF measurement, while the second photodiode detects light for phase difference detection. This merging of functions into fewer components resolves the contradiction by maintaining versatility while reducing configuration complexity compared to the conventional three-photodiode approach
Solution Approach 2:
Each photodiode in the patent serves multiple purposes. The first photodiode is used for both image capture and ToF measurement, while the second photodiode is used for both image capture and phase difference detection. This multi-functionality allows the system to perform both ranging methods with fewer components, resolving the contradiction between adaptability and device complexity
2Use of energy by moving object
If phase difference detection method is used to reduce power consumption, then power consumption is reduced, but it is difficult to measure distance of flat subjects
Solution Approach 1:
The patent merges both ToF and phase difference detection methods into a single imaging device with two photodiodes per pixel. This combination allows the system to measure distances to flat subjects using the ToF method while maintaining the low power consumption advantage of phase difference detection for other applications, thus resolving the contradiction between power consumption and measurement capability
Solution Approach 2:
The patent enables dynamic switching between ToF and phase difference detection methods based on the imaging requirements. When measuring flat subjects, the ToF method is activated; when measuring other subjects where phase difference detection is sufficient, that method is used to conserve power. This dynamic adaptability resolves the contradiction by allowing the system to optimize power consumption while maintaining measurement capability
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 allows for efficient distance measurement to both flat and non-flat subjects with reduced power consumption and complexity, enhancing the imaging device's ranging capabilities while maintaining accuracy.
Implementation Method 1
a first photoelectric conversion unit and a second photoelectric conversion unit that perform photoelectric conversion of incident light from an object
Data Source
AI summary
Imaging elements are disclosed. In one example, first and second photoelectric conversion units perform photoelectric conversion of incident light from an object. A first electric charge transfer unit transfers the electric charges generated by the first photoelectric conversion unit to a first electric charge holding unit. A second electric charge transfer unit transfers the electric charges generated by the first photoelectric conversion unit to a second electric charge holding unit. A third electric charge transfer unit transfers the electric charges generated by the second photoelectric conversion unit to the first electric charge holding unit. A fourth electric charge transfer unit transfers the electric charges generated by the second photoelectric conversion unit to the second electric charge holding unit. Image signals are generated based on the electric charges held in the first and second electric charge holding units.