Taper Tooth Gear Asymmetry for Tape Cartridge Rotation Lock
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Solution Overview
Problem
Existing recording tape cartridges face issues with maintaining a secure rotation lock state during falls due to relative posture variations between the brake member and the reel, requiring high precision in components and assembly for smooth meshing and locking, which is difficult to achieve.
Innovation Solution
A recording tape cartridge design featuring a reel side gear with piece taper teeth, where the winding mesh surface is parallel to the reel axis and the pull-out mesh surface is inclined, and a case side gear with corresponding mesh surfaces, allowing for secure meshing and locking, even during falls, using a mesh holding section to maintain the lock state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a mesh surface of the engagement gear and the brake gear is set to be parallel to a reel axis line, then a taper for guidance at the time of the mesh cannot be formed, but smooth meshing of the engagement gear and the brake gear requires high precision in components and an assembly
Solution Approach 1:
The patent applies asymmetry by designing piece taper teeth where one mesh surface is parallel to the reel axis line while the other mesh surface is inclined at a specific angle. This asymmetric configuration allows the gear to function differently in winding versus pull-out directions, enabling smooth meshing without requiring high precision assembly while still providing effective guidance through the inclined taper surface.
2Ease of operation
If a guide taper that is sufficient to smoothly mesh the engagement gear and the brake gear within a limited mesh stroke is provided, then a mesh area that is approximately parallel to the reel axis line may be decreased, but a rotation lock state by the brake member may be released at the time of falling
Solution Approach 1:
The patent applies local quality by providing different mesh surface orientations on different portions of the same tooth. One mesh surface is parallel to the reel axis line to maintain rotation lock state during falling, while the other mesh surface is inclined to enable smooth meshing within limited stroke. This localized differentiation of tooth surface properties allows both smooth operation and reliable locking to coexist.
3Area of stationary object
If a guide taper amount is decreased to secure a sufficient mesh surface, then it is difficult to smoothly mesh the engagement gear and the brake gear, but high precision in components and the assembly is required to maintain lock state during falling
Solution Approach 1:
The asymmetric piece taper tooth design allows one mesh surface to be parallel (providing sufficient mesh area for smooth operation) while the other surface is inclined (providing guidance function). This asymmetry enables both adequate mesh surface area and effective guidance without requiring high precision assembly, as the parallel surface naturally accommodates manufacturing tolerances.
4Ease of operation
If the reel is allowed to rotate freely, then smooth operation is achieved, but the reel may be displaced to be inclined with respect to the case due to impact when the cartridge falls
Solution Approach 1:
The patent applies preliminary anti-action by pre-configuring the piece taper teeth with one mesh surface parallel to the reel axis line, which creates a locking effect that prevents reel displacement during falling before the actual impact occurs. This preliminary structural arrangement counteracts the destabilizing effect of impact forces, maintaining reel stability while allowing free rotation during normal operation.
Data Source
AI summary
A recording tape cartridge includes a reel, a case where the reel is accommodated, an engagement gear that is provided in the reel, and a brake gear which is provided in the case side brake member and in which a mesh state with the engagement gear or a mesh release state with the engagement gear is switched by relative displacement of an axis line direction of the brake member with respect to the reel. In a piece taper tooth of the engagement gear, a mesh surface that is oriented in a winding rotation direction is approximately parallel to a reel axis line direction and an opposite mesh surface is inclined with respect to the reel axis line. A piece taper tooth of the brake gear is a taper tooth that is opposite to the piece taper tooth of the engagement gear.