Noise Suppressing Device for Image Reading Apparatus
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Solution Overview
Problem
Existing image reading devices suffer from high-frequency noise interference due to ungrounded circuit boards and lack of effective noise reduction mechanisms, leading to operational malfunctions and increased electromagnetic interference (EMI).
Innovation Solution
A noise suppressing device is implemented, featuring a first ungrounded circuit board connected to a grounded second circuit board through a transmission line with a high-frequency reducing element, such as a high-frequency reducing coil, to attenuate high-frequency signals excited on the ground lines, thereby reducing EMI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a circuit board is not grounded, then electromagnetic interference is reduced, but high-frequency noise interference increases causing operational malfunctions
Solution Approach 1:
The circuit board is divided into two separate boards: a first circuit board that remains ungrounded to maintain low EMI, and a second circuit board that is grounded to provide noise suppression. These boards are connected through a transmission line, allowing the system to benefit from both grounded and ungrounded configurations simultaneously.
Solution Approach 2:
A high-frequency reducing element (such as a ferrite bead or inductor) is introduced as an intermediary component in the transmission line connecting the two circuit boards. This element selectively attenuates high-frequency noise signals while allowing lower frequency signals to pass through, thereby suppressing noise without completely isolating the ungrounded board.
2Object-affected harmful factors
If a high-frequency reducing element is added to the transmission line, then high-frequency noise is suppressed, but device complexity increases
Solution Approach 1:
Instead of grounding the entire first circuit board or adding multiple noise suppression components throughout the system, the solution applies noise suppression locally at the connection point between the two boards. The high-frequency reducing element is placed only at this critical interface where noise transmission occurs, providing targeted noise suppression with minimal added complexity.
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 solution effectively reduces high-frequency noise in the range of 100 MHz to 1 GHz, preventing malfunctions and minimizing EMI, as demonstrated by a significant reduction in electromagnetic interference intensity from 200 to 700 MHz.
Implementation Method 1
a high-frequency reducing element that is arranged between the ground layer of the second circuit board and the ground line of the transmission line and that reduces a high-frequency signal excited at the ground line of the transmission line
Data Source
AI summary
A noise suppressing device includes a first circuit board not being grounded; a second circuit board connected to the first circuit board through a transmission line including a signal line that transmits a high-frequency signal and a ground line, the second circuit board including a ground layer being grounded; and a high-frequency reducing element that is arranged between the ground layer of the second circuit board and the ground line of the transmission line and that reduces a high-frequency signal excited at the ground line of the transmission line.