Lens Apparatus Cam Ring Ball Array Backlash Control
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Solution Overview
Problem
Conventional lens apparatuses face challenges in minimizing backlash and operation torque in the optical axis direction, leading to increased motor size and costs, due to existing cam ring mechanisms that often result in higher resistance and torque.
Innovation Solution
A lens apparatus design featuring a cam ring with one end surface in contact with a first ball array and the opposite end surface in contact with a second ball array, where the first ball array is held by a ring member and the second by a cap member, both biased by an elastic member to inhibit backlash and reduce torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spring biases the cam ring in the optical axis direction to prevent backlash, then backlash is reduced, but operation torque increases
Solution Approach 1:
The patent introduces ball arrays as intermediary elements between the cam ring and the fixed barrel/cam member. These balls mediate the contact, transforming sliding friction into rolling friction, thereby reducing the operation torque required to rotate the cam ring while maintaining backlash-free operation through the elastic member's biasing action
2Manufacturing precision
If tapered contact surfaces are used to prevent backlash, then positioning precision is improved, but sliding area and resistance increase
Solution Approach 1:
The ball arrays serve as intermediary elements that replace direct tapered surface contact. The balls maintain the positioning function of the tapered surfaces while eliminating the large sliding area, reducing resistance through rolling contact mechanics
3Reliability
If load is applied to sliding surfaces in the optical axis direction to prevent backlash, then backlash is reduced, but operation torque increases
Solution Approach 1:
The ball arrays act as intermediaries that carry the load from the elastic member's biasing action. By transferring the load through rolling contact rather than direct sliding contact, the operation torque is significantly reduced while maintaining the backlash prevention effect
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 design effectively inhibits backlash and prevents an increase in operation torque, reducing motor size and costs while maintaining optical performance, with the ball arrays reducing rotational resistance and the elastic member ensuring precise alignment.
Implementation Method 1
the ring member is biased by an elastic member toward the cam ring
Implementation Method 2
the first ball array is rotatably held by and between a ring member movable in the optical axis direction and the one end surface, the second ball array is rotatably held by and between a cap member fixed to the fixed barrel and the opposite end surface
Data Source
AI summary
A lens apparatus includes a can ring for moving an optical member in an optical axis direction by rotating about an optical axis relative to a fixed barrel. One end surface of the cam ring in the optical axis direction is in contact with a first ball array, while an opposite end surface of the cam ring in the optical axis direction is in contact with a second ball array, the first ball array is rotatably held by and between a ring member movable in the optical axis direction and the one end surface, the second ball array is rotatably held by and between a cap member fixed to the fixed barrel and the opposite end surface, and the ring member is biased by an elastic member toward the cam ring, and the cam ring is thereby biased toward the cap member.