Imaging Device Transistor Voltage Clipping for Blocked-Up Shadows
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Solution Overview
Problem
Existing imaging devices face the challenge of inhibiting the 'blocked-up shadows' phenomenon, particularly when exposed to high-intensity light, which results in darkened images due to the saturation of signal charges, and current solutions require complex circuit configurations.
Innovation Solution
The proposed imaging device incorporates a simple circuit configuration utilizing transistors with specific voltage control mechanisms to manage signal output levels, ensuring that the voltage at the output terminal is limited during both signal and reset periods, thereby preventing the appearance of blocked-up shadows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If clipping transistors are added to prevent blocked-up shadows, then the blocked-up shadows phenomenon is inhibited, but the circuit configuration becomes complex
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the threshold voltage of the transistor connected to the pixel output line. By changing the gate voltage of this transistor between a first voltage (first threshold) and a second voltage (second threshold), the circuit achieves clipping functionality without requiring additional clipping transistors. This parameter modulation resolves the contradiction by maintaining reliability through effective blocked-up shadow inhibition while simplifying the circuit configuration.
Solution Approach 2:
The patent makes the transistor connected to the pixel output line perform multiple functions: it acts as both a signal transfer switch and a clipping element. By controlling its threshold voltage dynamically, the same transistor provides both normal signal transmission and blocked-up shadow prevention, eliminating the need for separate clipping transistors and thus reducing circuit complexity while maintaining the inhibition effect.
2Reliability
If additional clipping circuits are used to inhibit blocked-up shadows, then the blocked-up shadows phenomenon is prevented, but the device complexity increases
Solution Approach 1:
The patent merges the clipping function with the existing transistor structure that connects to the pixel output line. Instead of adding separate clipping circuits, the invention combines the clipping capability into the functional transistor already present in the circuit. This merging approach prevents blocked-up shadows while avoiding the increase in device complexity that would result from adding independent clipping circuits.
3Reliability
If the transistor threshold voltage is dynamically adjusted, then the voltage clipping is optimized to prevent blocked-up shadows, but the control circuit complexity increases
Solution Approach 1:
The patent implements periodic action by switching the gate voltage of the transistor between two states (first voltage and second voltage) at different times. During the first period, the transistor operates with the first threshold voltage for normal signal transfer, and during the second period, it operates with the second threshold voltage for clipping. This time-division approach optimizes voltage clipping effectiveness while keeping the control mechanism relatively simple through periodic voltage switching.
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 approach effectively inhibits the blocked-up shadows phenomenon by controlling voltage levels and improving signal transfer characteristics, even under high-brightness conditions, without the need for additional transistors or complex clipping circuits.
Implementation Method 1
a first transistor that has a first gate, a first source, and a first drain, one of the first source and the first drain being connected to the output signal line; and a first circuit that is connected to the first gate, the first circuit being configured to generate a third voltage that is a voltage between a first voltage and a second voltage, the first voltage being a voltage for turning on the first transistor, the second voltage being a voltage for turning off the first transistor
Data Source
AI summary
There is provided an imaging device including: a pixel that outputs a pixel signal corresponding to an amount of incident light; an output signal line that is connected to the pixel to allow the pixel signal from the pixel to be output to the output signal line; a first transistor that has a first gate, a first source, and a first drain, one of the first source and the first drain being connected to the output signal line; and a first circuit that is connected to the first gate, the first circuit being configured to generate a third voltage that is a voltage between a first voltage and a second voltage, the first voltage being a voltage for turning on the first transistor, the second voltage being a voltage for turning off the first transistor.