Optical Element Drive Structure for Inductor Flux Shielding
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Solution Overview
Problem
In small-sized, thin camera-mounted devices, the use of ultrasound motors for lens driving requires high drive voltages, leading to leakage flux and noise due to inductors, which are difficult to suppress, especially with thin substrates like flexible printed boards.
Innovation Solution
An optical element driving device with a piezoelectric element, an inductor on a substrate, and a metal cover member with a flange part to house the inductor and suppress magnetic flux and noise leakage, using a metal layer to face the inductor and reduce leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If an inductor is used to increase input voltage to the ultrasound motor, then the drive voltage is sufficient, but magnetic flux and noise leak from the coil
Solution Approach 1:
A metal cover member is introduced as an intermediary component between the inductor and the external environment. This cover member includes a shielding layer that intercepts and contains the magnetic flux generated by the inductor, preventing it from leaking outward. The shielding layer acts as a mediator that blocks the harmful magnetic field while allowing the inductor to function normally for voltage boosting.
Solution Approach 2:
The harmful magnetic flux and noise are extracted or isolated from the main system by enclosing the inductor within a dedicated metal cover member. This separation allows the inductor to be contained and controlled, preventing its harmful emissions from affecting other components such as the piezoelectric element and circuit board.
2Object-affected harmful factors
If a metal cover is attached through bonding to suppress leakage flux and noise, then shielding is improved, but magnetic flux may leak from the bonding portion
Solution Approach 1:
The metal cover member incorporates a shielding layer specifically at the bonding portion and peripheral areas where magnetic flux leakage is most likely to occur. This localized shielding enhancement ensures that the bonding interfaces, which are potential leakage paths, are adequately protected without requiring complete re-design of the entire cover structure.
Solution Approach 2:
The metal cover member is constructed as a composite structure combining a base metal material with an additional shielding layer. This composite construction provides enhanced magnetic shielding properties, particularly at critical areas like bonding portions, by layering materials with complementary magnetic shielding characteristics.
3Length of stationary object
If a thin substrate like flexible printed board is used, then device thickness is reduced, but magnetic flux and noise leak from the substrate rear surface
Solution Approach 1:
Instead of attempting to block magnetic flux in the planar direction within the thin substrate, the solution extends the shielding into the vertical dimension by adding a metal cover member that covers the rear surface of the substrate. This three-dimensional shielding approach effectively blocks leakage paths that would otherwise escape through the thin substrate's rear surface.
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
Effectively suppresses magnetic flux and noise leakage, enhancing the performance and reliability of camera modules in camera-mounted devices by shielding electromagnetic waves.
Implementation Method 1
the input voltage is increased by using an inductor and supplied to the ultrasound motor
Implementation Method 2
a metal cover for covering the inductor is attached through bonding or the like to the substrate where the inductor is provided so as to suppress the leakage flux and the noise
Implementation Method 3
a piezoelectric element configured to drive a holding part configured to hold an optical element
Data Source
AI summary
An optical element driving device includes: a driving part configured to drive a holding part configured to hold an optical element; a substrate including a circuit including an inductor configured to increase an input voltage to the driving part; and a cover member comprising a metal and including an opening and a flange part extending at an outer periphery of the opening, the cover member being configured to cover the inductor in a state where the inductor is housed in the opening and the flange part is disposed on the substrate. The substrate includes a metal layer disposed to face the inductor. The metal layer is formed to include a region where the inductor is disposed in plan view.