Imaging Sensor Readout Layout for Shared Counter Output Lines
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Solution Overview
Problem
Existing imaging sensors face challenges in reducing circuit scale due to the large area occupied by readout lines, particularly when increasing the resolution of time counters, which leads to increased circuit complexity and difficulty in providing every pixel with its own time counter.
Innovation Solution
The proposed solution involves a sensor configuration where each pixel is equipped with a conversion unit to detect photons and pulse processing units to process generated pulses. These units include a time counter to count clocks from the start of exposure and pixel counters to count pulses, with shared output lines for count values, reducing the number of lines and circuit scale.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the resolution of time counter is increased to improve measurement precision, then the circuit scale increases
Solution Approach 1:
The patent merges the output lines of time counters and pixel counters into a shared readout line. By time-division multiplexing, both counter types use the same physical line for data output, eliminating the need for separate high-resolution time counter lines and reducing overall circuit scale while maintaining measurement precision.
Solution Approach 2:
The readout line is designed to serve multiple functions: it reads out data from both time counters and pixel counters, and can be selectively activated based on which counter needs to output data. This multi-functional approach reduces the total number of lines required in the circuit.
2Measurement precision
If the number of readout lines is increased to support higher resolution counters, then the area occupied by readout lines increases
Solution Approach 1:
Multiple counter output lines (time counter lines and pixel counter lines) are merged into a single shared readout line. The system uses control signals to selectively enable either time counter output or pixel counter output on the shared line, reducing the total line count and the area they occupy in the circuit.
Solution Approach 2:
The shared readout line operates in periodic time-division mode, alternating between reading time counter data and pixel counter data. This periodic switching allows a single line to handle multiple data streams sequentially, reducing the spatial requirements for readout infrastructure.
3Area of stationary object
If one time counter is coupled to multiple pixels to reduce circuit scale, then the measurement precision for individual pixels may be compromised
Solution Approach 1:
The patent segments the counting function into two independent counters: a time counter that measures duration and a pixel counter that measures photon count. By separating these measurement functions, each counter can be optimized for its specific purpose with appropriate resolution, while both share the same readout infrastructure, thus maintaining precision while reducing circuit scale.
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 the circuit scale by sharing output lines between time counters and pixel counters, allowing for exclusive output of count values, thereby minimizing the area occupied by readout lines and enhancing processing efficiency.
Implementation Method 1
pixels each provided with a conversion unit to detect incidence of photons
Data Source
AI summary
The processing unit of the sensor includes a time counter and pixel counters. The number of lines is reduced by sharing output lines with the pixel counters and the time counter. In addition, readout time is reduced by transposing an output sequence of pixel count values and time count values across Bayer units depending on a state of saturation of a pixel.