Endoscope Optical Unit Coatings for Low-Resistance VCM Focusing
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Solution Overview
Problem
The degradation of slide parts and generation of corrosion powder in voice coil motor (VCM) based optical units of endoscopes due to oxidation, frictional stress, and frictional heat lead to increased slide resistance, necessitating larger magnets and coils for accurate operation.
Innovation Solution
The implementation of oxidation prevention layers (first films) and stress reduction layers (second films) on the slide surfaces of the movable and fixed barrels, along with a voice coil motor, to prevent corrosion and reduce frictional stress, thereby minimizing slide resistance and allowing for downsizing of components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a voice coil motor is used to drive the movable barrel at high speed for autofocusing, then the focusing speed and responsiveness are improved, but the slide surfaces of the fixed barrel and movable barrel oxidize and degrade due to frictional stress and frictional heat, generating corrosion powder and increasing slide resistance
Solution Approach 1:
A protective film is formed on the slide surfaces of the fixed barrel and movable barrel before they undergo oxidation and degradation. This preliminary protective layer prevents the adverse effects of high-speed operation, allowing the voice coil motor to drive the movable barrel at high speed for autofocusing without the slide surfaces degrading and generating corrosion powder.
2Measurement precision
If the sizes of the magnet and coil in the voice coil motor are increased to accurately drive the movable barrel when slide resistance increases, then the driving accuracy is improved, but the overall size of the optical unit increases
Solution Approach 1:
By forming a protective film on the slide surfaces in advance, the oxidation and degradation of the surfaces are prevented, thereby preventing an increase in slide resistance. This allows the voice coil motor to accurately drive the movable barrel without requiring larger magnets and coils, thus avoiding an increase in the overall size of the optical unit.
3Ease of manufacture
If ultrasound clean is performed on the endoscope after use, then the cleaning effectiveness is improved, but the slide surfaces are further degraded by frictional stress and frictional heat from high-speed vibration, generating more corrosion powder and abrasion powder
Solution Approach 1:
A protective film is formed on the slide surfaces before the endoscope undergoes ultrasound cleaning. This protective layer prevents the slide surfaces from being further degraded by frictional stress and frictional heat during the high-speed vibration of ultrasound cleaning, thereby preventing the generation of corrosion powder and abrasion powder while still allowing effective cleaning to be performed.
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 solution effectively prevents oxidation and reduces frictional stress, enabling the use of smaller magnets and coils, thus achieving both improved operation performance and downsizing of the optical unit.
Implementation Method 1
a first film formed on at least one of slide surfaces of the fixed barrel and the movable barrel that slide relative to each other, the first film serving as an oxidation reaction prevention layer configured to prevent corrosion of the slide surface
Implementation Method 2
a voice coil motor configured to relatively move the movable barrel with respect to the fixed barrel in the optical axis direction by using a coil disposed at the fixed barrel and a magnet disposed at the movable barrel
Implementation Method 3
a second film interposed between the slide surface on which the first film is formed and the first film, the second film serving as a stress reduction layer configured to prevent crack of the first film
Data Source
AI summary
An objective optical unit includes: an observation optical system including a fixed lens and a moving lens; a fixed barrel holding the fixed lens; a moving lens barrel disposed in a coil holding barrel, holding a movable group lens, and moving in a direction along a photographing optical axis of the observation optical system; a first film formed on slide surfaces of the coil holding barrel and the moving lens barrel, the first film serving as an oxidation reaction prevention layer; a second film interposed between the slide surface where the first film is formed and the first film, the second film serving as a stress reduction layer; and a voice coil motor configured to relatively move the moving lens barrel with respect to the fixed barrel in an optical axis direction by using a coil disposed at the fixed barrel and a magnet disposed at the moving lens barrel.