Thermal Compensation Lens Barrel Structure for Focus Stability
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Solution Overview
Problem
Existing lens units in vehicles face challenges in suppressing deviation of focus position due to temperature changes, as the materials used in the lens frames cannot effectively adjust to thermal expansion, leading to inconsistent focus distances.
Innovation Solution
A lens unit design incorporating a first and second lens barrel member, a spacer, and an elastic member, where the spacer is made of a material with a higher linear expansion coefficient than the barrel members, and an elastic member, such as an O-ring, which elastically connects to the spacer, allowing the second lens barrel to move in response to temperature changes, maintaining focus position stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the lens unit uses conventional lens frames with fixed materials, then the structure is simple and easy to manufacture, but the focus position deviates when temperature changes
Solution Approach 1:
The lens barrel structure is transformed from a fixed rigid frame to a dynamic adjustable mechanism. The second lens barrel member can move along the optical axis in response to temperature changes, allowing the system to adapt its focus position dynamically rather than remaining static, thereby maintaining focus stability across temperature variations.
Solution Approach 2:
The invention changes the physical parameter of the lens barrel structure by introducing a movable second lens barrel member that can shift position along the optical axis. This parameter change enables the system to compensate for thermal expansion effects and maintain consistent focus position despite temperature fluctuations.
2Manufacturing precision
If the lens unit uses a fixed lens barrel structure, then the manufacturing precision requirement is low, but the focus distance changes with temperature
Solution Approach 1:
The lens barrel is segmented into a first lens barrel member and a second lens barrel member that can move independently relative to each other. This segmentation allows the second lens barrel to be adjusted separately to compensate for focus drift caused by temperature changes, improving focus distance control precision without requiring the entire lens assembly to be manufactured with extremely tight tolerances.
3Stability of the object's composition
If the lens unit uses materials with low linear expansion coefficients, then thermal stability is good, but the focus position cannot be adjusted to compensate for thermal effects
Solution Approach 1:
The movable second lens barrel member acts as an intermediary mechanism between the thermal expansion of lens components and the focus position. It translates thermal effects into controlled movement along the optical axis, allowing the system to adapt to temperature changes while maintaining overall thermal stability through the use of materials with appropriate expansion coefficients.
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 adjusts focus distance by moving the second lens barrel member in the optical axis direction, compensating for thermal expansion, thereby maintaining consistent focus position despite temperature fluctuations.
Implementation Method 1
a spacer in a tube shape which is disposed on an inner side of the first lens barrel member and is made of material whose linear expansion coefficient is higher than those of the first lens barrel member and the second lens barrel member
Implementation Method 2
an elastic member in a ring shape which is disposed on an inner side of the first lens barrel member. The first lens barrel member is provided with a first stepped part in a ring shape which is protruded from its inner peripheral side to an inner side in a radial direction, the second lens barrel member is provided with a second stepped part in a ring shape which is protruded from its outer peripheral side to an outer side in the radial direction
Data Source
AI summary
A lens unit includes a first lens barrel accommodating a first lens, a second lens barrel accommodating a second lens, a spacer whose linear expansion coefficient is higher than those of the first lens barrel and the second lens barrel, and an elastic member. The first lens barrel has a first stepped part and the second lens barrel has a second stepped part, and they face each other in an optical axis direction. The spacer is disposed between the first stepped part and the second stepped part and the elastic member is disposed in an elastically deformed state on an opposite side to the spacer in the optical axis direction. When temperature becomes higher, the spacer thermally expands in the optical axis direction and pushes the second lens barrel to crush the elastic member and thus, deviation of a focus position due to heat is suppressed.