Imaging Device Dual Output Switch Zero Ohmic Drop
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing imaging devices face challenges with ohmic drops on the output path of pixel signals, which introduce variable skew and reduce reading speed, particularly in large matrices, due to column resistances and capacitances, and previous solutions either require additional components or complex biasing schemes.
Innovation Solution
The imaging device incorporates a dual output switch configuration with separate data and current-supply conductors, allowing the current generator to supply pixels without adding components to the column edges and eliminating the need for biasing the current-source transistors, thereby minimizing ohmic drops and maintaining consistent signal representation across the matrix.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single current-source transistor is shared by multiple pixels in a column, then device complexity is reduced, but ohmic drops occur on the column conductor causing variable signal skew
Solution Approach 1:
The patent divides the current-source function into separate transistors for each pixel, eliminating the shared current-source transistor approach. Each pixel has its own current-source transistor that draws current from a local conductor, preventing ohmic drops on column conductors and ensuring accurate signal representation for all pixels regardless of position.
Solution Approach 2:
The patent introduces intermediate conductors (first and second conductors) that locally distribute current to each pixel's current-source transistor. These intermediate conductors act as mediators between the power supply and the pixel-level current sources, eliminating the need for a shared column-level current source and preventing associated ohmic drops.
2Loss of energy
If the width of column tracks is increased to reduce lineal resistance, then ohmic drops are reduced, but the electrical capacitance of columns increases
Solution Approach 1:
The patent segments the current distribution by assigning separate current-source transistors to each pixel, eliminating the need for high-capacitance wide column tracks. Each pixel draws current from its own local conductor, allowing use of narrower, lower-capacitance conductors while maintaining low ohmic drops through optimized local current paths.
3Measurement precision
If additional current-source transistors are added to each pixel, then ohmic drops are eliminated, but device complexity and the number of components increase
Solution Approach 1:
The patent implements segmentation by assigning one current-source transistor per pixel, which eliminates ohmic drops on column conductors. This approach balances signal accuracy with acceptable device complexity, as each pixel's current-source transistor is locally placed and independently controlled, avoiding the need for complex shared current-source arrangements.
4Power
If a voltage follower stage is used to read pixel signals, then signal amplification is achieved, but reading speed is reduced due to the time required to establish stable voltages
Solution Approach 1:
The patent applies preliminary action by pre-establishing stable voltages on the first and second conductors before pixel reading begins. The current-source transistors are configured to draw stable currents from these pre-biased conductors, allowing the voltage follower stage to immediately read pixel signals without waiting for voltage establishment, thereby increasing reading speed while maintaining signal amplification.
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 effectively reduces ohmic drops and maintains signal integrity across the matrix, allowing for faster and more accurate image capture without increasing power consumption or requiring additional components, thus addressing the limitations of previous solutions.
Implementation Method 1
a photosensitive zone delivering a current of electric charges as a function of the flux of photons which it receives
Implementation Method 2
a radiation converter called a scintillator which converts the incident radiation, for example X-ray radiation, into a radiation in a band of wavelengths to which the photosensitive elements present in the pixels are sensitive
Data Source
AI summary
An imaging device comprising comprises a matrix of pixels, at least one data conductor connected to several pixels of the matrix, organized row-wise and successively transporting signals delivered by respectively the pixels of the row and an electronic current generator supplying several pixels, each of the pixels comprising: a transistor delivering at the node of the pixel, the signal delivered by the pixel considered and wherein can flow a bias current from the current generator, and a first electronic switch connecting the node of the pixel to the data conductor associated with this pixel as a function of a selection signal of the pixel. Each of the pixels comprises a second electronic switch, distinct from the first electronic switch, joined to the node of the pixel, the current arising from the generator to be made to flow in the transistor as a function of the selection signal for the pixel.