Pyroelectric Sensor Shared Amplifier Circuit Design
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Solution Overview
Problem
Infrared detection circuits with pyroelectric elements require amplifier circuits in each pixel for reading pyroelectric charge, leading to increased pixel area and current, which slows down the scanning process due to the need for multiple irradiations and blockages during readout operations.
Innovation Solution
A sensor device with a shared amplifier circuit for multiple pixel columns, utilizing a reset switch to discharge electric charges during irradiation, allowing for high-sensitivity readout of all pixels in one time without individual amplifiers, enabling continuous light irradiation and faster scanning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If amplifier circuits are provided in each pixel to read pyroelectric charge, then detection sensitivity is improved, but pixel area and total pixel current become enormous
Solution Approach 1:
Multiple pixel circuits share a common amplifier circuit connected to a column line, consolidating what would otherwise be individual amplifiers in each pixel into a shared resource that serves multiple pixels simultaneously
Solution Approach 2:
The shared amplifier circuit serves multiple functions by reading pyroelectric charge from multiple different pixel circuits through the column line, making the amplifier a universal component for the entire column rather than a dedicated component for each pixel
2Measurement precision
If amplifier circuits are provided in each pixel, then pyroelectric charge can be read, but the scanning process slows down due to multiple irradiations and blockages required
Solution Approach 1:
Infrared rays can be continuously irradiated to all pixels simultaneously without interruption for blocking, as the shared amplifier architecture allows all pixel charges to be read during a single continuous irradiation period rather than requiring sequential blocking and reading operations
Solution Approach 2:
All pixel circuits are prepared with their pyroelectric elements charged during the same irradiation period before reading begins, allowing simultaneous readout of all pixels in the column without requiring multiple separate irradiation cycles
3Measurement precision
If multiple irradiations and blockages are performed during scanning to read pixels, then pixel charge can be read, but reading speed decreases
Solution Approach 1:
The system uses periodic switching of the reset switch during a single continuous irradiation to create distinct charging and discharging phases, allowing pyroelectric charge to be accumulated and then read in a timed sequence without requiring multiple separate irradiation events
Solution Approach 2:
The mechanical blocking of infrared rays is replaced by electronic control of the reset switch that discharges pyroelectric elements, substituting a mechanical irradiation-blocking system with an electronic charge-control system that achieves the same measurement goal more efficiently
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 allows for downsized sensor devices capable of high-sensitivity readout of multiple pixels during a single infrared irradiation, reducing the need for multiple irradiations and enhancing scanning speed.
Implementation Method 1
the pyroelectric element was irradiated by infrared rays and the change of the pyroelectric charge before and after the irradiation was read
Data Source
AI summary
A sensor device includes a plurality of row lines WL, a plurality of column lines DL, a plurality of reset lines RL, a plurality of pixel circuits that connect to each one of the plurality of row lines, the plurality of column lines and the plurality of reset lines, and an amplifier circuit. The plurality of pixel circuits respectively includes a pyroelectric element, a reset switch that is driven by the plurality of reset lines and discharges an electric charge of the pyroelectric element, and a pixel selection switch that is driven by the plurality of row lines and outputs a signal, which is based on a change of the electric charge of the pyroelectric element by a discharge, to one of the column lines. The signal based on the change of the electric charge of the pyroelectric element by the discharge is amplified in the amplifier circuit.