Solid State Imaging Device Background Light Elimination
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Solution Overview
Problem
Existing distance image measurement devices are complex due to the need to control four potential depths within individual pixels, complicating the device configuration and operation.
Innovation Solution
A solid state imaging device with a semiconductor substrate featuring a light-sensitive area, pairs of accumulation regions, and gate electrodes that control potential barriers to manage charge accumulation based on background light levels, allowing for simple distance image measurement by altering the height of potential barriers in response to background light intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If four potential depths within individual pixels are simultaneously controlled to eliminate background light, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts the background light elimination function from the pixel structure itself and implements it externally using a separate photodetector. The photodetector detects background light intensity and generates a control signal that adjusts the potential barrier height in the charge accumulation region, thereby eliminating background light interference without requiring complex internal pixel modifications.
Solution Approach 2:
The patent introduces a photodetector as an intermediary component between the light source and the pixel array. This photodetector mediates the background light detection and control process by converting background light intensity into electrical signals that regulate the potential barriers, simplifying the overall system architecture while maintaining measurement precision.
2Measurement precision
If multiple accumulation regions with differentiated timing are used to eliminate background light, then measurement precision is improved, but ease of operation deteriorates
Solution Approach 1:
The patent implements a feedback control mechanism where the photodetector continuously monitors background light intensity and dynamically adjusts the potential barrier height in real-time. This feedback loop automatically compensates for background light variations without requiring manual intervention or complex timing control, thereby maintaining high measurement precision while simplifying operation.
Solution Approach 2:
The patent transitions from static, pre-programmed accumulation timing to dynamic, real-time potential barrier adjustment. The potential barrier height is continuously adapted based on the detected background light intensity, allowing the system to automatically optimize its operation for varying lighting conditions without complex timing sequences.
3Measurement precision
If potential barrier height is dynamically adjusted based on background light, then measurement precision is improved, but use of energy increases
Solution Approach 1:
The patent changes the electrical parameter (potential barrier height) dynamically based on background light conditions. By adjusting only the voltage level rather than reconfiguring the entire pixel structure or activating multiple accumulation regions, the system achieves high measurement precision with minimal energy consumption. The photodetector and control circuitry consume negligible energy compared to full pixel reconfiguration.
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 distance image measurement by eliminating background light components and simplifying the device configuration, resulting in a more efficient and precise distance measurement process.
Implementation Method 1
photo-detection means for detecting a background light
Implementation Method 2
a pair of second gate electrodes that are provided on the semiconductor substrate so as to control the height of first potential barriers each interposed between the first accumulation region and the second accumulation region
Implementation Method 3
a phase difference between pulses at an emission and pulses at a return of a probe light is measured as a time of flight
Data Source
AI summary
A pair of first gate electrodes IGR, IGL are provided on a semiconductor substrate 100 so that potentials φTX1, φTX2 between a light-sensitive area SA and a pair of first accumulation regions AR, AL alternately ramp. A pair of second gate electrodes IGR, IGL are provided on the semiconductor substrate 100 so as to control the height of first potential barriers φBG each interposed between the first accumulation region AR, AL and a second accumulation region FDR, FDL, and increase the height of the first potential barrier φBG to carriers as a higher output of a background light is detected by a photodetector.