Imaging Pixel Power Current Switching for Uniform Image Quality
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing imaging devices face challenges in achieving high image quality due to variations in power supply current and voltage, which affect the uniformity of the load current and subsequently impact image capture.
Innovation Solution
The proposed imaging device includes a light-receiving pixel, a power supply, a driver, and a current circuit. The current circuit comprises a load, a load driving section, and a switch that allows a power supply current to flow through a current path when the voltage in the load changes by a predetermined voltage, ensuring a predetermined current value flows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple dummy pixels are provided to uniformize current source load, then image quality is improved, but device complexity increases
Solution Approach 1:
The patent extracts the load uniformization function from the pixel array by providing dummy pixels outside the effective imaging area. These dummy pixels are dedicated solely to current source load uniformization, separating this auxiliary function from the main imaging function and reducing complexity in the active pixel region.
Solution Approach 2:
The dummy pixels serve multiple functions: they uniformize the current source load across all pixels, provide a reference for readout circuitry, and maintain consistent power supply current characteristics. This multi-functionality reduces the need for separate dedicated circuits for each function.
2Ease of operation
If power supply current varies, then device operation is simplified, but image quality deteriorates due to load current non-uniformity
Solution Approach 1:
The patent implements feedback by using dummy pixels to sense power supply current variations and using this information to adjust and uniformize the current source load. The readout circuitry reads signals from dummy pixels to detect current variations and applies compensation to maintain uniform loading across all pixels despite power supply fluctuations.
3Reliability
If switch is turned on during voltage change period in load, then power supply current uniformity is improved, but device complexity increases
Solution Approach 1:
The switch is turned on in advance during the voltage change period in the load before the actual pixel readout begins. This preliminary action pre-establishes uniform power supply current conditions, compensating for upcoming current variations and ensuring stable operation during the critical imaging phase.
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 configuration enhances image quality by maintaining a uniform power supply current and voltage, thereby stabilizing the load current and improving the consistency of captured images.
Implementation Method 1
The light-receiving element generates electric charge corresponding to an amount of received light
Data Source
AI summary
An imaging device according to an embodiment of the present disclosure includes a light-receiving pixel, a power supply, a driver, and a current circuit. The light-receiving pixel includes a light-receiving element and a pixel transistor. The light-receiving element generates electric charge corresponding to an amount of received light. The power supply generates a first power supply voltage at a first power supply node. The driver drives the pixel transistor on the basis of the first power supply voltage at the first power supply node. The current circuit causes a power supply current to flow through a current path led to the first power supply node. The power supply current has a predetermined current value. The current circuit includes a load, a load driving section, and a switch. The load driving section drives the load. The switch is provided on the current path. The switch allows the power supply current to flow through the current path by being turned on in a period in which a voltage in the load changes by a predetermined voltage.