Dynamic Collection Gate Voltage for Dual-Mode Image Sensor
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Solution Overview
Problem
Current image sensing systems require separate pixel arrays for optical ranging and general camera modes, leading to increased manufacturing costs due to fixed collecting voltage limiting full well capacity during long exposure times.
Innovation Solution
An image sensing system with a pixel circuit that includes a photosensitive device, a transmission gate, and a collection gate with a non-fixed voltage collecting signal, allowing for expanded full well capacity by varying the collecting signal's voltage levels to enhance signal quality and enable operation in both modes with a single pixel array.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed voltage is applied to the collection gate in optical ranging mode, then the photoelectrons are collected efficiently for short pulsed light, but the full well capacity is limited for long exposure times in general camera mode
Solution Approach 1:
The collection gate voltage is changed from a fixed value to a dynamically controllable voltage that can be adjusted based on the operating mode. A voltage control circuit receives mode selection signals and accordingly adjusts the collection gate voltage to different levels, enabling the pixel circuit to adapt between optical ranging mode (higher voltage for efficient collection) and general camera mode (lower voltage for increased full well capacity during long exposure).
Solution Approach 2:
The invention changes the voltage parameter of the collection gate based on the operating mode. In optical ranging mode, the collection gate voltage is set to a first voltage level that optimizes photoelectron collection for short pulsed light. In general camera mode, the voltage is adjusted to a second level that expands the full well capacity for long exposure times, thereby resolving the contradiction between collection efficiency and storage capacity.
2Reliability
If separate pixel arrays are used for optical ranging mode and general camera mode, then each mode can be optimized independently, but the manufacturing cost increases
Solution Approach 1:
The pixel circuit is designed with multi-functionality to operate in both optical ranging mode and general camera mode using the same photosensitive device and collection gate. By incorporating a voltage control circuit that adjusts the collection gate voltage based on mode selection, a single pixel array can be optimized for both modes, eliminating the need for separate pixel arrays and thereby reducing manufacturing cost while maintaining mode-specific optimization.
Solution Approach 2:
The pixel circuit incorporates dynamic voltage control on the collection gate that allows it to switch between different operating characteristics. The voltage control circuit receives mode selection signals and adjusts the collection gate voltage accordingly, enabling the same hardware to adapt its behavior for optimal performance in either optical ranging or general camera mode, thus achieving universality without sacrificing mode-specific optimization.
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
The system achieves improved signal quality by storing more photoelectrons during longer exposures and reduces manufacturing costs by eliminating the need for separate pixel arrays for different modes.
Implementation Method 1
a first pixel circuit including a photosensitive device
Data Source
AI summary
The present invention provides an image sensing system (10), including a first pixel circuit (120), wherein the first pixel circuit includes a photosensitive device (PD); a first transmission gate (TG1), under the control of a first transmission signal and conducted during a first conduction time interval; and a collection gate (CG), coupled between the photosensitive device and the transmission gate and configured to receive a collecting signal (CX); and a control unit (14), configured to generate the collecting signal to the collection gate, wherein the collecting signal has a non-fixed voltage value.