Automotive Camera Tube Thermal Expansion Compensation
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Solution Overview
Problem
Automotive camera modules face challenges in maintaining focus over varying temperatures due to thermal expansion, which causes the image sensor to move out of the image plane, resulting in poor image clarity at extreme temperatures.
Innovation Solution
A camera module design featuring a tube with a higher thermal expansion coefficient than the housing part, allowing for compensation of thermal expansion by moving freely relative to the housing, ensuring the image sensor remains on the image plane across a wide temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the housing and lens assembly are rigidly connected, then the structural stability is improved, but the image sensor moves out of the image plane due to thermal expansion at extreme temperatures
Solution Approach 1:
The housing is divided into two separate parts: the main housing structure and the lens assembly housing. These two parts are connected through a flexible connection that allows relative movement. This segmentation enables each part to expand independently according to its own thermal expansion characteristics while maintaining overall structural stability and image plane alignment.
Solution Approach 2:
The patent utilizes thermal expansion parameter differences between the housing material and the lens assembly material. By selecting materials with different coefficients of thermal expansion, the design allows the lens assembly to move relative to the housing in response to temperature changes, thereby compensating for thermal expansion and maintaining precise image plane alignment.
2Reliability
If a complex thermal compensation mechanism is implemented, then the image clarity over temperature range is improved, but the device complexity increases
Solution Approach 1:
The thermal compensation mechanism operates automatically based on the inherent thermal expansion properties of the materials. When temperature changes occur, the lens assembly naturally moves relative to the housing due to differential thermal expansion, providing self-compensation without requiring external control systems, actuators, or complex mechanical devices.
Solution Approach 2:
The patent directly exploits thermal expansion as the compensation mechanism. By designing the housing and lens assembly with different thermal expansion characteristics, the system automatically compensates for temperature-induced focus shifts. This approach replaces complex active compensation systems with a simple passive thermal expansion-based solution.
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 maintains image clarity over a wide temperature range by compensating for both housing and lens assembly expansions, ensuring the image sensor detects clear images in motor vehicles.
Implementation Method 1
The tube and the housing part expand in opposite directions. The compensation effect can be achieved by the thermal expansion coefficient of the tube being higher than the thermal expansion coefficient of the housing part.
Data Source
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AI summary
A camera module (12) for a motor vehicle, comprising a lens assembly (20), a housing (22) having a back wall (32) and a front end (50) surrounding an opening (28), and an image sensor (24) carried by the back wall (32) and arranged within the housing (22) in or close to an image plane (A) of the lens assembly (20), said housing (22) comprising a lens holder (53) extending between the front end (50) and the back wall (32), said camera module (12) comprising a tube (26) which is fixed to the lens holder (53) at the front end (50) such that the tube (26) surrounds the opening (28) and extends from the opening (28) into the housing (22), wherein the lens assembly (20) is connected to a bottom end section of the tube (26) by a connecting means (71, 72), and wherein the thermal expansion coefficient of the tube (26) is higher than the thermal expansion coefficient of the lens holder (53), is characterized in that the connecting means (71, 72) extends over less than half of the axial length (hi,) of the lens assembly (20).