Actuator with Angular Ball Bearing for Stable Mirror Tilt
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Solution Overview
Problem
Existing actuators for holographic recording and reproduction face challenges in maintaining a stable support center point, leading to positional displacement of the reference light spot during scanning, and are often costly.
Innovation Solution
An actuator design featuring a supporting shaft held by an angular ball bearing and small balls, allowing tilting around a rotational fulcrum, combined with a magnetic driving mechanism and rotation restricting members, to stabilize the mirror's angle and prevent rotation around the axis, thereby maintaining the light spot's position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a gimbal mechanism with two torsion bars is used to support the mirror, then the mirror can be freely tilted in two directions, but the support center point varies with each gimbal mechanism making it difficult to set center points at one point
Solution Approach 1:
The support function is segmented between the angular ball bearing (providing tilt support) and the small balls (providing rotational support). This segmentation allows each component to perform its specific function independently, ensuring the support center point remains consistent while maintaining tilt freedom.
Solution Approach 2:
The invention changes the support mechanism from a gimbal structure with variable center points to an angular ball bearing structure with a fixed rotational fulcrum. This parameter change in the support mechanism ensures that the support center point remains at one consistent location while still allowing free tilting motion.
2Ease of operation
If the support center point is not determined, then the structure allows flexible movement, but the reference light spot shifts from a predetermined location generating read-out errors
Solution Approach 1:
Instead of allowing flexible movement and then trying to control the light spot position, the invention inverts the approach by first establishing a fixed rotational fulcrum through the angular ball bearing, which automatically ensures the light spot remains at the predetermined location while still permitting necessary movement flexibility.
3Reliability
If an Earth-top-type actuator with small balls is used, then the actuator is mechanically excellent, but it is expensive
Solution Approach 1:
The invention replaces expensive precision gimbal mechanisms with more affordable components like angular ball bearings and small balls that can be manufactured at lower cost while maintaining the necessary mechanical performance and reliability for the application.
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
The actuator effectively reduces positional displacement of the reference light spot, minimizing read-out errors and achieving cost-effectiveness by stabilizing the mirror's tilt around a single rotational center.
Implementation Method 1
a plurality of small balls disposed between an inner side of the opening and an outer side of the inner ring member, and the supporting shaft being held by the inner ring member
Implementation Method 2
The driving mechanism includes a magnet, a pair of yokes, and a plurality of driving coils, the magnet provided at either one of the fixed section and the movable section, the yokes disposed at respective poles of the magnet so that the yokes oppose each other, the plurality of driving coils disposed at the other of the fixed section and the movable section
Data Source
AI summary
An actuator in which, when a supporting shaft, where a mirror (control object) is provided, is tilted by receiving an electromagnetic force of a magnetic driving mechanism, small balls of a supporting mechanism move in an axial direction in a space provided between an outer base and an inner ring member. Therefore, the supporting shaft and the inner ring member holding the supporting shaft swing. At this time, since the inner ring member swings around a rotational fulcrum as center, the supporting shaft can swing around one rotational fulcrum as center at all times. A plurality of laid members serving as a rotation restricting member prevent rotation of the supporting shaft in a direction around the axis.