Keyboard Pointing Device Sensor Logic Substrate Separation
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Solution Overview
Problem
The existing pointing stick designs in laptops hinder thickness reduction due to the large area of the shield cover protruding from the rear surface of the keyboard substrate, limiting motherboard design freedom and increasing noise interference.
Innovation Solution
The logic substrate is separated from the sensor substrate and attached to the rear surface of the keyboard assembly, connected by a cable, reducing noise interference and allowing for a lower profile design, with the logic substrate optionally placed below the space key or in an attachment space formed by cutting the metal plate or membrane sheet, enhancing waterproofing and reducing height protrusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the logic PCB is mounted on the motherboard near the strain gauge, then noise interference is reduced, but the shield cover protrudes from the rear surface of the keyboard substrate, limiting motherboard design freedom and increasing laptop thickness
Solution Approach 1:
The patent divides the pointing device into two separate substrates: a sensor substrate mounted on the keyboard assembly near the strain gauge, and a logic substrate mounted on the motherboard. This segmentation allows the sensor substrate to be positioned close to the strain gauge (reducing noise in analog signals) while the logic substrate can be placed elsewhere on the motherboard without interfering with the keyboard assembly, thus resolving the contradiction between noise reduction and motherboard design freedom
Solution Approach 2:
The patent introduces a cable as an intermediary component to connect the sensor substrate and logic substrate. This cable allows the analog signal to be transmitted from the sensor substrate to the logic substrate over a longer distance without direct mounting constraints, enabling the sensor substrate to remain close to the strain gauge while the logic substrate can be positioned optimally on the motherboard without protruding from the keyboard assembly
2Productivity
If the logic PCB is mounted on the motherboard, then signal processing is improved, but the shield cover area protruding from the keyboard substrate increases, facilitating noise entry through cables
Solution Approach 1:
By segmenting the pointing device into sensor substrate and logic substrate, the patent allows the sensor substrate to be mounted directly on the keyboard assembly near the strain gauge, minimizing the length of the cable transmitting analog signals and reducing the area of the shield cover that would otherwise need to protrude. This segmentation maintains signal processing capability on the logic substrate while reducing noise entry pathways
3Object-affected harmful factors
If the pointing device uses a traditional structure with shield cover and base plate, then electromagnetic shielding is achieved, but the height of the pointing device increases, hindering thickness reduction of portable computers
Solution Approach 1:
The patent extracts the logic substrate from the traditional pointing device structure (which includes shield cover and base plate) and mounts it directly on the motherboard. This extraction eliminates the need for the shield cover and base plate to protrude from the keyboard assembly, significantly reducing the height of the pointing device while maintaining electromagnetic shielding through the keyboard assembly's own structure and the cable shielding
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 facilitates size and thickness reduction of portable computers, improves motherboard design flexibility, and reduces noise interference, enabling a more sensitive and compact pointing device.
Implementation Method 1
a sensor substrate which converts force applied to the operation post into an analog electric signal; strain gauges (not illustrated) are bonded on the rear surface of the sensor PCB 13 in X and Y directions
Data Source
AI summary
A pointing device is attached to a keyboard assembly. The pointing device includes an operation post; a sensor substrate that converts force applied to the operation post into an analog electric signal; a logic substrate that is attached to a rear surface of the keyboard assembly and generates a digital signal to move a cursor from the electric signal; and a cable that connects the sensor substrate and the logic substrate to each other. It is possible to reduce the area of a portion protruding to a lower side from the rear surface of the keyboard assembly in the vicinity of the operation post and to lower the height of the portion by separating the sensor substrate and the logic substrate from each other. Since the cable is separated from a motherboard, it is possible to reduce noise entering the cable which transmits an analog signal.