Lens Unit Flange-Mounted Heater for Optical Alignment
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Solution Overview
Problem
The positional accuracy of lenses in an optical axis direction is compromised due to the presence of a flexible printed circuit board with a heater, leading to variations in optical performance.
Innovation Solution
A lens unit design where the flexible printed circuit board with a heater is disposed on the image-side flange surface of the first lens, with a regulation portion on the lens holder contacting the outer peripheral region of the flange surface, and a counterbore portion accommodating the extension of the circuit board, avoiding interference and maintaining positional accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the flexible printed circuit board with heater is disposed between the first lens and the lens barrel, then condensation inside the lens unit can be suppressed, but the positional accuracy of the first lens in the optical axis direction is lowered
Solution Approach 1:
The flexible printed circuit board is extracted from the space between the first lens and lens barrel, and repositioned to the image-side flange surface of the first lens. This removes the harmful interference of the circuit board with the lens positioning while preserving its condensation prevention function through direct heating of the lens surface.
Solution Approach 2:
The image-side flange surface of the first lens serves as an intermediary platform for mounting the flexible printed circuit board. This intermediary location allows the heater to function effectively for condensation suppression without interfering with the optical path or lens positioning mechanisms.
2Stability of the object's composition
If the flexible printed circuit board is pressed and crushed, then it can be secured in position, but thickness variation increases causing optical performance to vary
Solution Approach 1:
The flexible printed circuit board is relocated from the axial direction (between lenses) to the radial direction (on the flange surface). This dimensional change allows the board to be secured through peripheral engagement and adhesive bonding without requiring axial compression that would cause thickness variation.
Solution Approach 2:
The mounting structure is segmented into multiple fixation points around the periphery of the flange surface, allowing the circuit board to be secured stably without uniform compression across its entire area, thereby maintaining thickness uniformity.
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
Suppresses condensation and maintains optical performance by directly heating the lens, while preventing the flexible printed circuit board from affecting the positional accuracy of the first lens, thus stabilizing the optical axis alignment.
Implementation Method 1
The heater is an electric heating wire disposed on the surface of an annular flexible printed circuit board (caliber plate) having thermal conductivity. The temperature around the lens is raised by energizing the electric heating wire to generate heat.
Data Source
AI summary
A lens unit 1 includes a plurality of lenses aligned in a row along an optical axis L and a lens holder 2. A first lens L1 located the closest to an object-side La includes an object-side lens surface 11, an image-side lens surface 12, and an image-side flange surface 13. A first housing portion 4 accommodating the first lens L1 in the lens holder 2 includes a regulation portion 42 regulating a position of the first lens L1 in the optical axis L direction. The regulation portion 42 includes a lens seating surface 40 in contact with the first lens L1. The image-side flange surface 13 of the first lens L1 includes an outer peripheral region 13A in contact with the lens seating surface 40 of the regulation portion 42 and an inner peripheral region 13B in which a flexible printed circuit board 8 is disposed.