HDR Image Sensor Offset Compensation With Fast Settling
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Solution Overview
Problem
Existing image sensing devices face issues with offset voltage occurrence and increased settling time due to dual conversion gain methods, which affect the generation of high dynamic range (HDR) images.
Innovation Solution
The image sensing device employs a voltage control circuit that compensates for offset voltage and reduces settling time by selectively adjusting paths within the compensation circuit, using a single circuit to manage both offset level and boosting operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dual conversion gain method is used to vary conversion gain of pixels for HDR imaging, then image quality for high and low illuminance is improved, but offset voltage occurs and settling time increases
Solution Approach 1:
The patent segments the conversion gain control into two distinct paths: a first path for controlling offset voltage and a second path for boosting sensing voltage. This segmentation allows independent optimization of each function, resolving the contradiction by preventing offset voltage occurrence while maintaining fast settling time for HDR imaging.
Solution Approach 2:
The patent introduces a voltage controller as an intermediary component that manages the conversion gain variation process. This intermediary coordinates the switching between different conversion gains and controls the timing of voltage adjustments, ensuring that offset voltage is compensated while settling time is minimized for high-quality HDR image acquisition.
2Measurement precision
If dual conversion gain method is used to vary conversion gain of pixels for HDR imaging, then image quality for high and low illuminance is improved, but offset voltage occurs
Solution Approach 1:
The patent segments the conversion gain control into two distinct paths: a first path for controlling offset voltage and a second path for boosting sensing voltage. This segmentation allows independent optimization of each function, resolving the contradiction by preventing offset voltage occurrence while maintaining fast settling time for HDR imaging.
Solution Approach 2:
The patent converts the potential harmful effect of conversion gain switching into a beneficial outcome by using the switching process to enable dual conversion gain operation for HDR imaging. The voltage controller manages the switching to minimize offset voltage while maximizing the benefit of having both high and low conversion gain modes available for different illuminance conditions.
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 enables the generation of HDR images by effectively compensating for offset voltage and reducing settling time, maintaining image quality and efficiency in capturing a wide range of lighting conditions.
Implementation Method 1
An image sensing device is a device for capturing optical images by converting light into electrical signals using a photosensitive semiconductor material which reacts to light
Implementation Method 2
a pixel configured to output to a sensing node, a sensing voltage corresponding to a voltage of a floating diffusion region, which is included therein and has first and second capacitances in respective first and second modes
Data Source
AI summary
An image sensing device capable of generating a high dynamic range (HDR) image is disclosed. The image sensing device includes a pixel and a compensation circuit. The pixel configured to output to a sensing node, a sensing voltage corresponding to a voltage of a floating diffusion region, which is included therein and has first and second capacitances in respective first and second modes, the second capacitance being greater than the first capacitance. The compensation circuit controls, in a first section, an offset voltage level of the sensing node through a first path and boosts, in a second section, the sensing voltage through a second path.