Offset PMT Module Asymmetry for Compact Housing
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Solution Overview
Problem
Conventional photomultiplier tube modules lack further miniaturization capabilities, limiting their compactness and efficiency in detecting weak light.
Innovation Solution
A photomultiplier tube module design that includes a photomultiplier tube with its light incident surface on the housing's front surface, a high-voltage generating circuit board intersecting the tube axis, and a signal processing board adjacent to the tube wall, allowing for compact housing and noise suppression through a metal layer connected to ground, along with a digital circuit for digital signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the photomultiplier tube module uses conventional compact housing design, then the module achieves small size, but further miniaturization is limited
Solution Approach 1:
The patent applies asymmetry by positioning the photomultiplier tube's extension line offset from the center of gravity of the front surface. This asymmetric arrangement creates unused space on one side of the housing that can be utilized for mounting circuit boards, enabling more efficient space utilization and further miniaturization of the overall module.
Solution Approach 2:
The patent utilizes three-dimensional space optimization by arranging the high-voltage generating circuit board to intersect the tube axis and positioning the signal processing board on the opposite side. This spatial arrangement in multiple dimensions allows all components to be compactly housed within the housing, achieving miniaturization through effective volumetric utilization.
2Volume of moving object
If the signal processing board is placed close to the photomultiplier tube for compactness, then housing space is reduced, but noise interference increases
Solution Approach 1:
The patent introduces a metal layer as an intermediary shielding structure between the signal processing board and the photomultiplier tube. This metal layer acts as a barrier that blocks electromagnetic noise while allowing the signal processing board to be positioned close to the tube for compact housing, thus resolving the contradiction between miniaturization and noise reduction.
3Shape
If the tube axis is centered on the front surface, then structural symmetry is maintained, but space utilization for circuit boards is reduced
Solution Approach 1:
The patent deliberately breaks structural symmetry by offsetting the tube axis from the center of gravity of the front surface. This asymmetric design choice creates additional usable space on one side of the housing, which is then utilized to mount the high-voltage generating circuit board and signal processing board, thereby improving space utilization for circuit boards.
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
Achieves miniaturization and enhanced noise shielding while enabling accurate photon counting by outputting digital values based on square waves from the comparator, improving photodetection of weak light.
Implementation Method 1
when photons are made incident into the light incident surface, the photomultiplier tube outputs a pulse current
Implementation Method 2
a high-voltage generating circuit board which is fixed in the housing, whose board surface is arranged so as to intersect the extension line of the tube axis, and which applies an operating voltage to the photomultiplier tube
Implementation Method 3
a metal layer provided between the digital circuit and the photomultiplier tube and the high-voltage generating circuit board and connected to a ground
Data Source
AI summary
An extension line of a tube axis of a photomultiplier tube is shifted from the center of gravity position of a front surface of a housing, which allows a space to be formed at an opposite side in the housing. A signal processing board is arranged in this space, and a high-voltage generating circuit board is fixed on the extension line of the tube axis, and thus the interior space of a housing can be effectively used. Since the signal processing board can be made adjacent to a tube wall of the photomultiplier tube, even when the length in a tube axis direction of the signal processing board is long, it becomes possible to house the same in the housing. Therefore, it becomes possible to achieve miniaturization.