Photoelectric Conversion Pixel Diode Reset Mechanism
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Solution Overview
Problem
Existing photoelectric conversion apparatuses face challenges in reducing dark current noise while maintaining a small pixel size, as they require complex structures like reset transistors and capacitors, which increase pixel size.
Innovation Solution
A photoelectric conversion apparatus with a semiconductor substrate and pixels that incorporate a diode with impurity diffused portions of different conductivity types, where the controlling unit applies specific voltages to set the diode into forwardly and reversely biased states, reducing dark current noise without the need for a reset transistor and minimizing pixel size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a reset transistor and reset controlling capacitor are added to execute zero biased resetting operation, then dark current noise is reduced, but pixel size increases
Solution Approach 1:
The patent extracts the reset function from the traditional reset transistor and capacitor implementation and relocates it to the photoelectric conversion layer itself through controlled potential distribution. By applying specific potentials to different regions of the photoelectric conversion layer, the reset operation is achieved without requiring separate reset transistor and capacitor components, thereby reducing pixel size while maintaining dark current noise reduction capability
Solution Approach 2:
The photoelectric conversion layer is given multiple functions: it serves both as the light-to-electricity conversion medium and as the reset control mechanism. By utilizing the same photoelectric conversion layer for both photoelectric conversion and reset operations through differential potential application, the patent eliminates the need for dedicated reset components, achieving component reduction while maintaining functionality
2Ease of operation
If a reset transistor and controlling wiring are formed in each pixel, then resetting operation is achieved, but device complexity increases
Solution Approach 1:
The patent merges the reset control function with the photoelectric conversion function by applying reset potentials directly to regions of the photoelectric conversion layer. This integration eliminates the need for separate reset transistors, capacitors, and controlling wirings in each pixel, thereby simplifying the pixel construction while maintaining the ability to perform resetting operations
Solution Approach 2:
The photoelectric conversion layer performs the reset operation on itself through controlled potential distribution. By applying specific potentials to different regions of the same layer, the system achieves self-resetting functionality without requiring external reset control components, reducing device complexity while maintaining operational 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 solution effectively reduces dark current noise and allows for high-speed resetting operations while maintaining a compact pixel size, enhancing the performance of image sensors.
Implementation Method 1
a photoelectric conversion layer provided between the first electrode layer and the second electrode layer
Implementation Method 2
the diode has a first impurity diffused portion of a first conductivity type and a second impurity diffused portion of a second conductivity type; the controlling unit applies a voltage adapted to set the first impurity diffused portion and the second impurity diffused portion into a forwardly biased state and a voltage adapted to set the first impurity diffused portion and the second impurity diffused portion into a reversely biased state
Data Source
AI summary
A photoelectric conversion apparatus and an imaging system with reduced dark current noise while suppressed pixel size are provided. Each pixel has a photoelectric conversion unit and a diode. The photoelectric conversion unit has a first electrode layer, a second electrode layer between the first electrode layer and a semiconductor substrate, and a photoelectric conversion layer between the first electrode layer and the second electrode layer. A diode has a first impurity diffused portion of a first conductivity type and a second impurity diffused portion of a second conductivity type. The second electrode layer is connected to the first impurity diffused portion. The controlling unit applies a voltage to set the first impurity diffused portion and the second impurity diffused portion into a forwardly biased state and a voltage to set the first impurity diffused portion and the second impurity diffused portion into a reversely biased state to the diode.