Switch Device Vertical Resistor Layout for Compact Wiring Detection
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Solution Overview
Problem
Conventional switch devices are difficult to downsize due to the lateral arrangement of chip resistors on the circuit board, making them larger than the board itself and hindering weight reduction and installation in narrow spaces.
Innovation Solution
The switch device configuration includes a circuit unit and contact mechanism on the same surface of the circuit board, with resistive elements positioned perpendicular to the contact mechanism's movement direction, allowing for a non-overlapping layout that shortens the device's length and eliminates the need for a separate circuit board, using a lead frame with recesses for resistive elements to enhance bonding and reduce component count.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chip resistors are laterally arrayed on the circuit board, then the electric circuit can be formed to detect wiring disconnection and short circuit, but the switch device becomes larger than the circuit board in lateral direction, making downsizing difficult
Solution Approach 1:
The patent changes the arrangement dimension of chip resistors from lateral (parallel to circuit board surface) to vertical (perpendicular to circuit board surface). Specifically, chip resistors are disposed standing on the circuit board surface, with their longitudinal directions extending in directions substantially perpendicular to the circuit board surface. This dimensional change allows the electric circuit to be formed in the vertical direction rather than lateral direction, enabling downsizing of the switch device in lateral dimensions while maintaining wiring detection functionality.
2Reliability
If chip resistors are laterally arrayed on the circuit board, then the electric circuit functionality is achieved, but the switch device cannot be downsized for weight reduction or installation in narrow spaces
Solution Approach 1:
The patent applies vertical arrangement of chip resistors perpendicular to the circuit board surface, transforming the circuit layout from a planar (2D) configuration to a three-dimensional (3D) configuration. This allows the switch device to be downsized in lateral dimensions, directly reducing overall device weight and enabling installation in narrow spaces while preserving the electric circuit's ability to detect wiring disconnection and short circuit conditions.
3Reliability
If chip resistors are laterally arrayed on the circuit board, then the electric circuit can detect wiring issues, but the switch device lateral size exceeds the circuit board size
Solution Approach 1:
The patent reorients chip resistors to stand vertically on the circuit board surface, with their longitudinal axes extending perpendicular to the board. This vertical orientation enables the formation of detection circuits in the vertical dimension, concentrating the device's length in the vertical direction rather than extending it laterally. Consequently, the switch device achieves compact lateral dimensions suitable for narrow space installation while maintaining accurate wiring detection capability through properly configured detection circuits.
Data Source
AI summary
A switch device has a circuit unit that forms an electric circuit that detects at least one of disconnection and a short circuit of a wiring connecting an external device and the switch device, two terminals connected to the electric circuit, and configured to be connected to the wiring, a contact mechanism that moves in a movable direction to switch on and off of a contact of the electric circuit, and a circuit board on which the circuit unit, the two terminals, and the contact mechanism are disposed. The electric circuit comprises at least one resistive element. The circuit unit and the contact mechanism are disposed on an identical surface side of the circuit board. The resistive element is disposed in a direction perpendicular to the movable direction of the contact mechanism when viewed from at least a part of a movable range of the contact mechanism.