Handheld Printer Power Key Reaction Force Adjustment
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Solution Overview
Problem
Handheld printers face issues with mistaken operation of power and function keys due to their miniaturized size and adjacent placement, leading to accidental power off during normal operation, especially when convex key designs protrude and cause operational inconveniences and portability issues.
Innovation Solution
The handheld printer incorporates a battery chamber cover with a locked and engaged structure, featuring locking and protruding parts to securely store the battery, and adjusts reaction forces for power and function keys to prevent mistaken operation, allowing for accurate key presses and maintaining portability without changing key shapes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the power key and function key are adjacently disposed to improve space efficiency and miniaturization, then the device size is reduced, but the possibility of mistaken operation increases
Solution Approach 1:
The patent applies different surface shapes to different keys: the power key has a convex surface that protrudes from the device surface, while function keys have flat surfaces. This local differentiation allows adjacent keys to be disposed close together while preventing mistaken operation through tactile and visual distinction.
Solution Approach 2:
The power key is designed with an asymmetric convex surface shape that differs from the flat function keys. This asymmetry creates distinct tactile feedback and visual appearance, enabling users to easily identify the power key among adjacent function keys without requiring larger spacing.
2Reliability
If convex-shaped keys are used to prevent mistaken operation, then mistaken operation is prevented, but the device portability and miniaturization are compromised
Solution Approach 1:
Instead of making all keys convex, only the power key has a convex surface that protrudes from the device. The function keys remain flat and flush with the device surface, maintaining a sleek profile suitable for portability while still providing mistaken operation prevention through the differentiated power key design.
Solution Approach 2:
The convex shape is applied partially only to the power key rather than all keys. This partial application provides sufficient mistaken operation prevention for the critical power function without the excessive bulk that would result from making all keys convex, thus balancing reliability with portability.
3Reliability
If the power key requires larger pressing force to prevent mistaken operation, then mistaken operation is prevented, but the ease of operation decreases
Solution Approach 1:
The convex shape of the power key performs the prevention function in advance by creating tactile and visual distinction before the pressing action occurs. Users can identify the power key through touch and sight before pressing, eliminating the need for excessive pressing force while still preventing mistaken operation.
Solution Approach 2:
The patent replaces the mechanical solution of requiring large pressing force with a geometric/tactile solution using convex shape. The physical distinction created by the convex surface provides feedback that guides correct operation without increasing the mechanical force requirement, improving ease of operation while maintaining reliability.
Data Source
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AI summary
[object] To provide a handheld printer capable of preventing mistaken operation of a power key and function key adjacently disposed. [Solving means] A bulging volume h1 of a bulging part 39a of a metal dome member 39 of a power key 30 is configured to be greater than a bulging volume h2 of a bulging part 49a of a metal dome member 49 of a feed key 40. As a result, the metal dome member 39 applies a larger reaction force than the metal dome member 49, necessitating a larger pressing force for operating the power key 30 than when operating the feed key 40.