Solid-State Image Sensor Dark Current Correction via Bias Voltage Control
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Solution Overview
Problem
Conventional solid-state image sensors face challenges in improving the accuracy of dark current correction, which affects image data noise, as increasing the number of light-shielded pixels to enhance correction accuracy reduces the photosensitive region area.
Innovation Solution
A solid-state image sensor and method that involve a bias voltage supply unit to provide different bias voltages to light-shielded and photosensitive pixels during signal output periods, and a signal processing unit to process dark current noise using light-shielded pixel signals, allowing for distinct dark current rate increases and improved correction accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of light-shielded pixels is increased to improve dark current correction accuracy, then the correction accuracy is improved, but the photosensitive region area is reduced
Solution Approach 1:
The patent applies parameter changes by varying the bias voltage applied to light-shielded pixels across different time periods. Specifically, a first bias voltage is applied during a first period and a second bias voltage (different from the first) is applied during a second period. This temporal variation in bias voltage parameters enables the generation of dark current signals under different conditions, improving correction accuracy without requiring additional light-shielded pixels, thereby preserving the photosensitive region area.
2Measurement precision
If different bias voltages are supplied to light-shielded and photosensitive pixels at different time periods, then dark current correction accuracy is improved, but the device complexity increases
Solution Approach 1:
The patent implements periodic action by dividing the operation into distinct time periods with different bias voltage applications. A first bias voltage is supplied during a first period when light-shielded pixel signals are being output, and a second bias voltage is supplied during a second period when photosensitive pixel signals are being output. This periodic switching of bias voltage conditions enables the system to generate and process dark current signals under controlled, alternating conditions, improving correction accuracy while managing device complexity through temporal separation of functions.
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 enhances the accuracy of dark current correction, reducing noise in image data and maintaining a larger photosensitive region area, thereby improving image quality.
Implementation Method 1
This brings about an effect that dark currents having different rates of increase are generated in the light-shielded pixel and the photosensitive pixel
Data Source
AI summary
To improve the correction accuracy in a solid-state image sensor that performs dark current correction. A solid-state image sensor includes a bias voltage supply unit and a signal processing unit. The bias voltage supply unit supplies a bias voltage of a predetermined value to a light-shielded pixel impervious to light in a period in which a light-shielded pixel signal is output from the light-shielded pixel, and supplies a bias voltage of a value different from the predetermined value to a photosensitive pixel not impervious to light in a period in which a photosensitive pixel signal is output from the photosensitive pixel. The signal processing unit executes processing of removing dark current noise from the photosensitive pixel signal using the light-shielded pixel signal.