Solid-State Image Capture Device Signal Line Control
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Solution Overview
Problem
Solid-state image capture devices, such as CMOS image sensors, face challenges in increasing readout speed without increasing power consumption, as methods to enhance readout speed often result in higher power consumption due to increased current usage and settling time.
Innovation Solution
The implementation of a solid-state image capture device with unit pixels that include transfer gates, signal lines, and current sources, where connections between the unit pixels and signal lines, and signal lines and current sources are electrically cut off during the transfer period, reducing parasitic capacitance-induced potential variations and settling time without increasing current amounts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the gradient of a slope is increased to increase the frequency of a counter for counting a time, then the conversion time is reduced and readout speed is improved, but the power consumption increases
Solution Approach 1:
The patent applies preliminary action by pre-charging the signal line to a predetermined potential before charge transfer begins. This preparation eliminates the need for increased current during the actual conversion process, as the signal line is already ready to receive and stabilize the signal without requiring additional power to overcome capacitance effects.
Solution Approach 2:
The patent implements dynamics by dynamically controlling the potential of the signal line through a dedicated circuit that adjusts the potential based on the transfer period. This dynamic potential control allows the system to maintain fast readout speeds while optimizing power consumption by only applying necessary voltage adjustments during critical phases rather than continuously increasing current.
2Speed
If the amount of current for use by a circuit is increased and the settling time is reduced, then the readout speed is improved, but the power consumption increases
Solution Approach 1:
The signal line is pre-charged to a predetermined potential before the charge transfer operation begins. This preliminary charging action ensures that the signal line is ready to immediately stabilize the transferred signal without requiring additional current increases, thereby reducing settling time without increasing power consumption.
Solution Approach 2:
The patent changes the potential parameter of the signal line dynamically during the transfer period using a dedicated control circuit. By adjusting the potential to match the transferred charge level, the system achieves faster settling time while maintaining constant or reduced current levels, thus improving readout speed without increasing power consumption.
3Reliability
If the connection between unit pixels and signal lines is maintained during the transfer period, then the signal can be read out, but the parasitic capacitance causes potential variation and increases settling time
Solution Approach 1:
The patent introduces a signal line potential control circuit as an intermediary between the unit pixels and the signal lines. This intermediary circuit actively manages the potential of the signal line during the transfer period, compensating for parasitic capacitance effects and preventing potential variations that would otherwise increase settling time, thereby maintaining both signal reading reliability and fast settling.
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 allows for increased readout speed without elevated power consumption by maintaining signal line stability and reducing settling time, thereby enhancing the performance of solid-state image capture devices.
Implementation Method 1
charges resulting from photoelectric conversion performed by photoelectric converting sections
Data Source
AI summary
A solid-state image capture device includes unit pixels including transfer gates that transfer charges to diffusion layers, the charges being obtained by photoelectric conversion performed by photoelectric converting sections; signal lines to which signals output from the unit pixels are read out: current sources connected to the signal lines; and a driver that electrically cuts off connections between the unit pixels and the signal lines and the signal lines and the current sources in a transfer period of the transfer gates.