button design challenge
constraints & criteria
Challenged to design a device that requires a battery door mechanism to house and cover two AA batteries while opening from a downwards button push.
functional requirements
user requirements
considerations & assumptions
Button system activates from a force of ≈ 2N
Button depresses ≈ 2.5mm
Withstand 1000 cycles of open/closing to account for replacements and fidgeting
System is easy to set / reset
Battery is easily removable
Design maintains cosmetic standards
Resistant to unintentional activation
Uses dimensions 4.02” x 2.43” x 0.78”
Electronics are not within design scope
Accounts for ease of manufacturing and assembly
Assumes AA battery follows dimension of 0.55” diameter and 1.95” length
conceptual design
Several real life mechanisms helped draw inspirations for concepts ~ water bottle buttons, iPhone sim card mechanisms, mechanical pens, TV remotes
design 1 - front view
design 2 - side view
A decision matrix was conducted, weighing the signifiant factors of the decison, ultimately suggesting conceptual design 1 as datum.
design & assembly
The final design uses a downwards button press push 2 slider blocks apart, causing the lids retention feature to come out of place, releasing the compression springs that push the lid upwards. Compression springs allow the system to push the lid back in place and reset. The slider blocks are slotted within grooves and housed under a secured hood, using locating features to constrain the Y & Z positions.
Before button press state
Activated state
Slider moves out of lid interlock
Springs push lid upwards
Push down on lid to reset
parts & validation
Performed finite element analysis on critical components subject to repeated button actuation forces to validate the structural integrity and lifecyle durability.
bill of materials
Costs are in USD
Initial tooling and labour costs are not accounted for
