Two-Stage Pixel Comparator for Wider DVS Dynamic Range
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In dynamic vision sensors (DVS), the contrast sensitivity control range is limited when the comparator gain is high, making it difficult to widen the dynamic range effectively.
Innovation Solution
A solid-state imaging device with pixel circuits that include a generation unit for logarithmic photocurrent voltage, a capacitor, and two-stage amplifiers with different gains, where the first amplifier has a lower gain than the second amplifier, allowing for wider voltage input and reduced contrast sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the comparator gain is increased to improve detection sensitivity, then the contrast sensitivity increases, but the voltage input range becomes limited and the dynamic range cannot be widened
Solution Approach 1:
The single comparator is divided into a two-stage comparator structure with a first comparator and a second comparator. The first comparator processes the input voltage with a first gain, and the second comparator processes the output of the first comparator with a second gain. This segmentation allows the system to handle a wider voltage input range while maintaining detection sensitivity through the combined gain effect.
Solution Approach 2:
The patent extends the voltage processing capability by adding an additional dimension in the form of a second comparator stage. This dimensional extension allows the system to process voltages that exceed the input range of a single comparator while preserving the ability to detect contrast changes through the cascaded gain structure.
2Adaptability or versatility
If the threshold voltage is adjusted to widen the dynamic range, then the adaptability improves, but the contrast sensitivity control range remains limited by the comparator gain
Solution Approach 1:
The patent implements dynamic gain control in the two-stage comparator structure. The first gain and second gain can be independently adjusted, allowing the system to dynamically adapt to different input conditions. This dynamic configuration enables the system to maintain optimal contrast sensitivity across a wider dynamic range by adjusting the respective gains of the two comparator stages.
Solution Approach 2:
The patent changes the system parameters by introducing two independent gain parameters (first gain and second gain) instead of a single gain parameter. This parameter expansion allows for finer control over the overall gain and contrast sensitivity, enabling the system to achieve both wide dynamic range and precise contrast sensitivity control simultaneously.
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 enables the imaging device to capture images in a wider dynamic range by adjusting the gain of the amplifiers, thereby reducing contrast sensitivity and expanding the voltage input range.
Implementation Method 1
a photoelectric conversion element to output a photocurrent
Data Source
AI summary
An imaging device includes pixel circuit including a generation unit generating a voltage; a capacitor having a first electrode to which the voltage is applied; a first amplifier having a first input terminal, connected to a second electrode of the capacitor, and a second input terminal, to which a first reference voltage is applied to, to output a result by comparing the voltage with the first reference voltage; a switch unit controlling a connection between the output of the first amplifier and the first input terminal; and a second amplifier having a third input terminal, to which the output of the first amplifier is connected, and a fourth input terminal, to which a second reference voltage is applied, to output a result by comparing the voltage with the second reference voltage, in which a first gain of the first amplifier is lower than a second gain of the second amplifier.