CCD Spectroscopic Device Vertical Binning Noise Reduction
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Solution Overview
Problem
In spectroscopic measurements, CMOS image sensors suffer from a lower signal-to-noise (SN) ratio due to integrated readout noise during vertical binning, compared to CCD image sensors.
Innovation Solution
A spectroscopic device utilizing a CCD type imaging element with pixels arranged in rows and columns, where charges are accumulated column-wise and readout noise is minimized, allowing for improved SN ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If vertical binning is performed using a CMOS image sensor, then the number of stages can be increased to improve signal accumulation, but readout noise is integrated and increases with the number of stages, resulting in lower SN ratio
Solution Approach 1:
The patent replaces the conventional CMOS image sensor with a CCD type imaging element. This substitution fundamentally changes the noise characteristics by eliminating the readout noise integration problem inherent in CMOS sensors. The CCD architecture allows charge accumulation without repeated readout operations, thereby maintaining high SN ratio while achieving vertical binning.
Solution Approach 2:
The patent changes the fundamental parameter of the image sensor from CMOS to CCD type. This parameter change transforms the noise behavior from readout-noise-dominated (CMOS) to readout-noise-free (CCD) during vertical binning operations, enabling improved SN ratio while maintaining signal accumulation capability.
2Measurement precision
If vertical binning is performed using a CCD image sensor, then readout noise does not increase with the number of stages, but the reading speed becomes slower compared to CMOS with horizontal transfer circuits
Solution Approach 1:
The patent introduces dynamic exposure control where the exposure period is adjusted based on the number of vertical binning stages. By extending the exposure time proportionally to the number of stages, the system maintains optimal charge accumulation while managing readout timing. This dynamic adjustment resolves the contradiction between maintaining high SN ratio through vertical binning and achieving fast reading speeds.
3Measurement precision
If the number of vertical binning stages is increased, then the SN ratio is improved through better signal accumulation, but heat generation increases causing noise
Solution Approach 1:
The patent implements dynamic exposure control where the exposure period is adjusted according to the number of vertical binning stages. By optimizing the exposure time to match the charge accumulation requirements, the system achieves high SN ratio without excessive heat generation. The dynamic adjustment prevents overheating while maintaining effective signal accumulation.
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
The device achieves excellent SN ratio in spectroscopic spectrum data acquisition by avoiding readout noise increase and enhancing reading speed and noise suppression.
Implementation Method 1
a pixel unit including a plurality of pixels arranged in a row direction along a wavelength resolution direction of the light and in a column direction perpendicular to the row direction, an accumulation unit arranged for each column at an end portion in the column direction of the pixel unit and accumulating charges generated in pixels of each column
Data Source
AI summary
A spectroscopic device receives light wavelength-resolved in a predetermined direction by a spectroscopic optical system including a spectroscopic element to acquire spectroscopic spectrum data of the light, and the spectroscopic device includes: a CCD type imaging element including a pixel unit including a plurality of pixels arranged in a row direction along a wavelength resolution direction of the light and in a column direction perpendicular to the row direction, an accumulation unit arranged for each column at an end portion in the column direction of the pixel unit and accumulating charges generated in pixels of each column, and a readout unit outputting an electrical signal of each column corresponding to a magnitude of the charge accumulated in the accumulation unit; a semiconductor element converting the electrical signal of each column into a digital signal and outputting the digital signal; and a generation unit generating spectroscopic spectrum data on the basis of the digital signal.