Electromagnetic Actuator Rotor Protrusion for Camera Blade Torque
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Solution Overview
Problem
Conventional electromagnetic actuators used in cameras face challenges in securing sufficient driving torque and magnetic attraction force when reduced in size, leading to unstable operation of shutter or diaphragm blades.
Innovation Solution
The electromagnetic actuator incorporates a rotor with a magnetized outer peripheral surface, a driving pin, and a protrusion part magnetized to the same pole as the rotor surface, which increases the magnetic interaction area with the yoke, allowing for stable maintaining and driving forces while preventing excessive magnetic attraction and torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the electromagnetic actuator is reduced in size without changing the conventional structure, then the actuator size is reduced, but the driving torque and magnetic attraction force become insufficient
Solution Approach 1:
The rotor surface is changed from a simple cylinder to a circumferential protrusion structure, utilizing the circumferential dimension to increase the effective magnetic interaction area without increasing the radial or axial dimensions of the actuator. This allows the actuator to maintain sufficient driving torque and magnetic attraction force while keeping the overall size reduced.
Solution Approach 2:
The protrusions are strategically positioned on the rotor surface to create localized areas of enhanced magnetic interaction with the stator poles. This local enhancement of magnetic coupling efficiency increases the driving torque and holding force without requiring a proportional increase in the overall actuator size.
2Volume of moving object
If the rotor is made smaller to reduce actuator size, then the actuator is more compact, but the stability of blade member operation deteriorates
Solution Approach 1:
By utilizing the circumferential dimension through protrusions, the magnetic interaction area is increased without increasing the rotor's radial or axial size. This maintains sufficient magnetic attraction force for stable blade operation while keeping the rotor compact.
Solution Approach 2:
The rotor surface is segmented into multiple protrusions that interact with different stator poles at different positions. This segmentation allows for more uniform distribution of magnetic forces, improving the stability and reliability of blade member operation despite the reduced rotor size.
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 enables the actuator to generate desired maintaining and driving forces effectively, ensuring stable operation of camera blades despite size reduction, with the protrusion part enhancing magnetic attraction when unpowered and repulsion when powered.
Implementation Method 1
a magnetizing coil, and a yoke that has a circular arc surface facing the outer peripheral surface of the rotor, a first magnetic-pole part, and a second magnetic-pole part. The first and second magnetic-pole parts generate mutually different magnetic poles by energizing the coil.
Implementation Method 2
the rotor includes a magnetized rotor part that defines the outer peripheral surface of the rotor and that is magnetized to have different magnetic poles in a circumferential direction, a driving pin that is not magnetized so as to rotate together with the magnetized rotor part, and a protrusion part that is protruded in a radial direction from the outer peripheral surface of the rotor while being magnetized to have the same magnetic pole as the outer peripheral surface of the rotor and that faces the first magnetic-pole part or the second magnetic-pole part.
Data Source
AI summary
An electromagnetic actuator includes a rotor rotatable within a predetermined angular range, a magnetizing coil, and a yoke having an arcuate surface facing the rotor, and first and second magnetic-pole parts that have mutually different magnetic poles upon energizing the coil. The rotor includes a magnetized rotor part defining the outer peripheral surface of the rotor and magnetized to have different magnetic poles, a non-magnetized driving pin rotatable with the magnetized rotor part, and a protrusion part protruding radially from the rotor and facing the first or second magnetic-pole part while being magnetized to have the same magnetic pole as the outer peripheral surface of the rotor. The surface of the rotor that faces the yoke and that exerts a magnetic action is increased due to the inclusion of the protrusion part, and hence a desired maintaining force and driving torque can be obtained.