Focal-Plane Shutter Drive Member Positioning Stability
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Solution Overview
Problem
Focal-plane shutters with drive members can tilt during rotation, altering the rotation start position and affecting the operating properties of blades, leading to variations in exposure times and image quality.
Innovation Solution
Incorporating a positioning portion that overlaps with the first and second gear portions in a plane perpendicular to the axis, ensuring the drive member remains aligned and stable, preventing tilting and maintaining consistent rotation start positions for the blades.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a positioning portion abuts the drive member to define rotation start position, then the rotation start position is defined, but the drive member tilts from desired posture due to force applied at different position along rotational axis
Solution Approach 1:
The patent resolves the contradiction by transitioning from one-dimensional positioning (abutting surface) to two-dimensional positioning (abutting surface + overlapping gear portions). The positioning portion is configured to abut the drive member at a first position defining rotation start position, while gear portions overlap at a second position along the rotational axis. This dimensional extension prevents tilting by distributing constraint forces across multiple locations, simultaneously achieving precise rotation start position definition and posture stability.
2Ease of operation
If force is exerted on the drive member at a different position in the direction of the rotational axis, then the drive member can be positioned, but the drive member tilts from its desired posture
Solution Approach 1:
The patent applies local quality by differentiating the functional characteristics of different regions of the positioning portion. The first position features an abutting surface with specific orientation for defining rotation start position, while the second position features overlapping gear portions for preventing tilting. Each region is optimized for its specific function, allowing the positioning portion to simultaneously achieve ease of positioning and posture stability through spatially differentiated local characteristics.
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 stabilizes the drive member's rotation start position, minimizing variations in blade movement and exposure times, thus maintaining consistent image quality.
Implementation Method 1
a drive member including a second gear portion meshing with the first gear portion, rotating about a predetermined axis, and driving the blade
Data Source
AI summary
A focal-plane shutter includes: a board including an opening; a blade opening and closing the opening; a rotor of an actuator for driving the blade; an output member rotated by the rotor and including a first gear portion; a drive member including a second gear portion meshing with the first gear portion, rotating about a predetermined axis, and driving the blade; and a positioning portion abutting with the drive member and defining an end of a rotational range of the drive member, wherein the first and second gear portions and the positioning portion overlap one another in a plane direction perpendicular to the axis.