Pixel Light Detection Circuit With Switchable Parallel Outputs
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Solution Overview
Problem
Existing imaging devices struggle with difficulty in switching the response characteristics of pixels.
Innovation Solution
A light detection element with a photodiode, conversion transistors, and a connection switching section that allows for switching the number of parallel outputs based on subject illuminance or detected events, enabling dynamic adjustment of response characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple conversion transistors are connected in parallel to switch response characteristics, then adaptability is improved, but device complexity increases
Solution Approach 1:
The pixel circuit is segmented into multiple conversion transistor units (first conversion transistor and one or more second conversion transistors) that can be independently controlled. Each transistor unit can be switched on or off to provide different response characteristics, allowing the system to adapt to various imaging conditions without requiring a completely different circuit design for each scenario.
Solution Approach 2:
The circuit introduces dynamic switching capability through the connection switching section that controls the electrical connection state of the second conversion transistor. This allows the pixel to dynamically adjust its response characteristics based on real-time imaging conditions such as illuminance levels or detected events, transitioning between different operational modes as needed.
2Measurement precision
If event detection section is added to detect voltage signal changes, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The conversion transistors serve multiple functions: they convert photocurrent to voltage signals for normal imaging operations, and simultaneously enable event detection by monitoring voltage signal changes. The same hardware infrastructure supports both standard pixel operation and event-based detection, eliminating the need for separate dedicated event detection circuits.
Solution Approach 2:
The pixel circuit performs self-detection of events by monitoring its own voltage signal changes through the connection switching section. When the voltage signal changes indicate an event condition, the circuit automatically responds by switching the connection state of the second conversion transistor, enabling the pixel to autonomously adapt to detected events without requiring external control.
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 dynamic adjustment of pixel response characteristics, reducing power consumption and processing load by outputting only relevant pixel signals, enhancing imaging efficiency.
Implementation Method 1
a photodiode that photoelectrically converts incident light to generate a photocurrent
Data Source
AI summary
Response characteristics are switched.A light detection element includes: a photodiode that photoelectrically converts incident light to generate a photocurrent; a first conversion transistor that converts the photocurrent into a voltage signal and outputs the voltage signal from a gate; a current source transistor that supplies a predetermined constant current to an output signal line connected to the gate of the first conversion transistor; a voltage supply transistor that supplies a constant voltage according to the predetermined constant current from the output signal line to a source of the first conversion transistor; one or more second conversion transistors connected in parallel to the first conversion transistor and capable of converting the photocurrent into the voltage signal and outputting the voltage signal from a gate, and a connection switching section that switches a number of parallel outputs by switching an electrical connection state of the second conversion transistor, the number of parallel outputs being a number of the second conversion transistors that are connected in parallel to the first conversion transistor and convert the photocurrent into the voltage signal and output the voltage signal from the gate.