Image Sensor Array with Segmented Pixel Integration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional image sensor arrays, such as CCD and CMOS, lose time-dependent information due to accumulation characteristics, which is critical in applications like laser range gated imaging and fluorescence lifetime imaging requiring fast electronic shutters with shutter times in the order of tens of nanoseconds, and existing image intensifiers add noise and are costly.
Innovation Solution
The image sensor array employs multiple pixel sensor elements that can be switched on and off within a video frame period to generate multiple video frame segments, each containing a small signal package, with a storage element to accumulate desired image information and avoid unwanted noise, using a pixel architecture with six transistors and a capacitor for improved signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If conventional image sensor arrays (CCD or CMOS) are used, then the device complexity is low and manufacturing is easy, but time-dependent information is lost due to accumulation characteristics during frame exposure
Solution Approach 1:
The image sensor array is divided into multiple independently controllable pixel sensor elements that can be switched on and off individually. Each pixel element functions as a separate integration unit with its own transfer switch, allowing selective accumulation of photons during specific time segments while preventing parasitic signal accumulation in other segments. This segmentation enables preservation of time-dependent information by controlling which pixels accumulate signals during each frame period.
2Speed
If image intensifiers with fast electronic shutters are used, then shutter times can be reduced to tens of nanoseconds for laser range gated imaging, but noise is added and cost increases
Solution Approach 1:
The patent extracts and removes the image intensifier component from the imaging system, replacing it with a solid-state image sensor array that has built-in fast electronic shuttering capability at the pixel level. By taking out the external image intensifier, the source of added noise and high cost is eliminated, while the required fast shuttering function is achieved through the transfer switch mechanism that can rapidly transfer accumulated charge between storage nodes.
Solution Approach 2:
The mechanical/optical shuttering mechanism of image intensifiers is replaced with an electronic switching mechanism implemented through transfer switches in each pixel element. This substitution uses electronic control signals to rapidly transfer charge packets between accumulation nodes, achieving nanosecond-scale shutter speeds without the mechanical moving parts, high voltages, and associated noise of traditional image intensifier shutters.
3Reliability
If multiple gated images are integrated within one frame exposure, then signal to noise ratio is improved, but the ability to resolve time-dependent events within the frame is lost
Solution Approach 1:
The image sensor array implements dynamic control of pixel integration periods through independently controllable transfer switches. Each pixel element can dynamically switch between different accumulation modes: some pixels accumulate signals during early time segments while others accumulate during later segments. This dynamic temporal segmentation allows the system to maintain high signal-to-noise ratio through selective integration while preserving time-dependent event information by assigning different temporal windows to different pixels.
Solution Approach 2:
The patent adds a temporal dimension to the spatial pixel array by introducing multiple accumulation nodes per pixel element that can be independently controlled in time. This creates a time-resolved spatial map where different regions of the sensor capture photons from different time segments, effectively adding the time dimension to the traditional two-dimensional spatial image, thereby preserving time-dependent information while maintaining signal integration benefits.
4Speed
If high-voltage switching is used in image intensifiers, then fast electronic shuttering is achieved, but device complexity and cost increase
Solution Approach 1:
The patent changes the operating voltage parameter from high voltage (kilovolt range in image intensifiers) to low voltage (volt range in solid-state pixels). The transfer switches operate with standard CMOS-compatible voltages, eliminating the need for high-voltage power supplies, insulation structures, and specialized high-voltage electronics. This parameter change maintains fast shutter response through rapid electronic switching while dramatically reducing device complexity and cost.
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 significantly improves the signal-to-noise ratio by eliminating unwanted parasitic image signal information and reduces the need for high-voltage switching, enabling high-speed imaging with reduced noise and cost compared to traditional image intensifiers.
Implementation Method 1
a photocathode capable of releasing electrons into said vacuum chamber when exposed to light impinging from an image on said photocathode
Implementation Method 2
electric field means for accelerating said released electrons from said photocathode towards aforementioned image sensor array
Implementation Method 3
a light sensitive element capable of generating and outputting an electric signal in dependence of light impinging on said light sensitive element
Data Source
Figure 1
Figure 2
AI summary
The invention relates to an image sensor array having multiple pixel sensor elements along the surface area of said image sensor and outputting at a specified video frame rate subsequent video frames corresponding to the image, characterized in that each multiple pixel sensor element is arranged for generating one or more video frame segments, said segments each having a time duration being a fraction of the time equivalent to the video frame rate, and composing a single video frame from the multiple of said video frame segments. The invention also relates to said pixel sensor element for use with an image intensifier or in an electron bombarded image sensor array device according to the invention.