Encoder Grating Orientation for Lens Frame Stability
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Solution Overview
Problem
Existing image stabilization apparatuses suffer from optical axis displacement due to play in the lens moving frame, leading to deteriorated image stabilization performance, especially when scales are arranged perpendicular to the radial direction from the optical axis.
Innovation Solution
The image stabilization apparatus is designed with encoders that have a higher sensitivity to radial displacements than rotational displacements by orienting the scale grating in a radial direction about the optical axis, reducing the sensitivity in the rotational direction and minimizing optical axis displacement without additional components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If scales are arranged perpendicular to the radial direction from the optical axis, then the encoder can detect radial displacements, but the lens moving frame rotation due to play causes significant optical axis displacement
Solution Approach 1:
The patent changes the orientation parameter of the scale grating from perpendicular to radial direction. This parameter change transforms the encoder's sensitivity characteristics, making it highly sensitive to radial displacements while being less sensitive to rotational displacements, thereby resolving the contradiction between detection precision and optical axis stability
Solution Approach 2:
The patent creates asymmetric sensitivity in the encoder by orienting the scale grating radially. This asymmetry causes the encoder to respond differently to radial versus rotational movements, with higher sensitivity to radial displacements and lower sensitivity to rotations, thus reducing the impact of play-induced rotations on optical axis stability
2Ease of operation
If the lens moving frame is mechanically supported with play, then the structure allows movement, but position control to return the frame to desired position causes optical axis displacement
Solution Approach 1:
The patent changes the detection parameter orientation to radial alignment, which fundamentally alters how the encoder responds to movements. This parameter change ensures that when the lens moving frame returns to its desired position after rotation due to play, the encoder's radial sensitivity minimizes false detection signals, preventing unnecessary corrective actions that would displace the optical axis
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 significantly reduces optical axis displacement and enhances image stabilization performance by minimizing the impact of play in the lens moving frame's rotational movement, as demonstrated by reduced displacement calculations.
Implementation Method 1
two or more encoders each including a scale and a detector, the scale being arranged such a way that the direction of arrangement of a grating of the scale is oriented in a radial direction about an optical axis
Data Source
AI summary
An image stabilization apparatus for a lens apparatus that moves an image stabilizing lens perpendicularly to optical axis includes a fixed barrel, a lens moving frame holding the image stabilizing lens and movable relative to the fixed barrel perpendicularly to the optical axis, an actuator that drives the lens moving frame relative to the fixed barrel, and the encoders used to determine the position of the lens moving frame relative to the fixed barrel. Each encoder includes a scale fixed to either the lens moving frame or the fixed barrel and a detector fixed to the other, the scale is arranged so that its grating is arranged in a radial direction about the optical axis so that the encoder has sensitivity to radial displacement of the lens moving frame about the optical axis which is higher than sensitivity to rotational displacement of the lens moving frame about the optical axis.