CN-121424961-B - Composite constraint layer damping vibration attenuation structure for curved mirror

CN121424961BCN 121424961 BCN121424961 BCN 121424961BCN-121424961-B

Abstract

The invention discloses a composite constraint layer damping vibration attenuation structure for a curved mirror, and belongs to the technical field of optical precision instruments. The structure comprises a curved lens, a viscoelastic material layer laid on the back surface of the curved lens, and a metal constraint sheet attached to the viscoelastic material layer. The core is that the metal constraint sheet has non-uniform rigidity and mass distribution which are cooperatively designed. The cross section of the composite material is a stepped profile formed by alternately connecting a plurality of web sections and wing plate sections, the preset rigidity gradient distribution along a specific direction is realized by enabling the web sections to have lengths which are in gradient change, and meanwhile, an opening array is integrally formed on each plate section forming the stepped profile so as to realize the preset mass distribution. Through collaborative design, the structure can couple a plurality of high-frequency vibration modes such as bending and torsion of the lens, and the energy is efficiently dissipated. The invention effectively solves the problems of image shake and blurring caused by lens vibration in a vehicle-mounted head-up display system by adopting a light and miniaturized structure.

Inventors

SUN XUKE
XIONG ZHONGQING
ZHENG WEIJIA
WANG QING
SHEN JINQIANG
HU SHAOWEI
LIU HONGWEI

Assignees

宁波锦辉光学科技股份有限公司

Dates

Publication Date: 20260508
Application Date: 20251230

Claims (8)

1.A composite constrained layer damping vibration attenuation structure for a curved mirror, comprising: A curved lens (10); a layer (20) of viscoelastic material applied to the back of the curved lens (10), and A metallic constraining sheet (30) affixed to the layer of viscoelastic material (20), the metallic constraining sheet (30) being configured to have both a predetermined stiffness profile and a predetermined mass profile; The metal constraint sheet (30) has a profile plane defining a cross-sectional profile thereof and a longitudinal extension direction perpendicular to the profile plane, wherein the cross-sectional profile of the metal constraint sheet (30) is a continuous stepped profile formed by alternately connecting a plurality of plate sections, the stepped profile is composed of a plurality of first web sections (31), second web sections (32) and wing sections (33) which are sequentially connected along a first direction, and each wing section (33) is connected with one first web section (31) and one second web section (32) so that the first web sections (31) and the second web sections (32) are staggered on both sides of the wing sections (33); Wherein said predetermined stiffness profile exhibits a stiffness gradient along said first direction by providing a plurality of said first web segments (31) with a graded length dimension, or providing a plurality of said second web segments (32) with a graded length dimension, or providing both with a graded length dimension, said length dimension being in said first direction; the predetermined mass distribution is achieved by integrally forming an array of openings in the first web section (31), second web section (32) and wing section (33) forming the stepped profile; The predetermined stiffness distribution and the predetermined mass distribution are cooperatively designed such that the metallic constraining sheet (30) as a whole has at least two tuned resonant frequencies respectively coupling a bending vibration mode and a torsional vibration mode of the curved lens (10).
2. The composite constrained layer damping vibration attenuation structure of claim 1, wherein the tuned resonance frequency is set in the range of 0.9 to 1.1 times the corresponding modal resonance frequency of the curved lens (10).
3. The damping vibration attenuation structure of composite constraint layer according to claim 1, wherein the arrangement density and/or size of the opening array is determined according to the vibration mode displacement distribution of the curved lens (10) corresponding to the vibration mode, wherein the arrangement density of the openings in the area with larger vibration mode displacement is lower or smaller, and the arrangement density of the openings in the area with smaller vibration mode displacement is higher or larger.
4. The composite constrained layer damping vibration attenuation structure of claim 1, wherein the specific parameters of the preset stiffness distribution and preset mass distribution are iteratively determined based on a finite element topology optimization algorithm with the minimization of the vibrational displacement response of the curved lens (10) at one or more target frequencies as an optimization objective.
5. The composite constrained layer damping vibration attenuation structure of claim 1, wherein the layer of viscoelastic material (20) is configured such that it exhibits a shear loss factor greater than 0.5 when excited at the one or more target frequencies when its temperature is within a preset operating temperature interval of the vehicle in which it is located.
6. The composite constraining layer damping vibration attenuation structure according to claim 1, wherein micro-ribs (40) for suppressing local high frequency resonance of the plate section are further integrally formed on the surface of at least one of the first web section (31), the second web section (32) or the wing section (33).
7. The composite constraining layer damping vibration attenuation structure according to claim 1, characterized in that the material of the metallic constraining sheet (30) is a metallic material or a metal matrix composite material with high inherent damping characteristics to form a composite damping effect with the viscoelastic damping of the viscoelastic material layer (20).
8. The composite constraint layer damping vibration attenuation structure according to claim 1, wherein at least one piezoelectric element (50) is further provided on a surface of at least one of the first web section (31), the second web section (32) or the wing section (33) constituting the stepped profile, the piezoelectric element (50) being configured to acquire a vibration signal of the curved lens (10) and generate a force in opposite phase to the vibration signal upon receiving a control signal to actively cancel the vibration.

Description

Composite constraint layer damping vibration attenuation structure for curved mirror Technical Field The invention relates to the technical field of optical precision instruments, in particular to a vibration suppression structure, and more particularly relates to a composite constraint layer damping structure of a curved reflector for high-precision imaging, which is applied to a vehicle-mounted head-up display system. Background A vehicle head-up display (HUD) is an advanced display technology that projects key driving information such as vehicle speed and navigation through an optical assembly into a view directly in front of a driver. The imaging quality of HUD systems, especially the stability and sharpness of images, is critical to driving safety and user experience. A typical HUD optical engine (PGU) generally includes an image source, a folding mirror, and a final curved mirror having a complex free-form surface shape. This curved mirror is one of the most precise, critical optical elements in the HUD system, and the accuracy of its surface shape directly determines whether the projected image is distorted. However, in practice, HUD systems are typically installed deep in the vehicle's instrument desk. The instrument desk itself is subject to continuous vibrations transmitted from the engine and the uneven road surface. Such vibrations, particularly high frequency components thereof, are inevitably transmitted to the curved mirror within the HUD module and excite the natural resonant modes (e.g., higher order bending modes and torsional modes) of the lens. Once the lens resonates, the following effects will be caused: 1. image dithering-the projected image can be subject to high frequency, small amplitude, severe dithering, resulting in "blurring" of numbers and lines or "ghosting". 2. And the image is blurred, namely the projection light path is changed suddenly due to the dynamic deformation of the lens, so that the imaging focal plane continuously jumps, and the image becomes blurred. To solve this industry problem, the prior art attempts the following methods: 1. HUD lenses are made extremely thick or are provided with an extremely heavy, extremely rigid metal or composite support. This approach adds significant weight and bulk to the HUD module, which is unacceptable in the space of the inside of the instrument desk where the gold is located. 2. And a common damping film is stuck on the back surface of the lens. The method has extremely low efficiency for inhibiting specific high-frequency resonance peaks concentrated in energy, and can treat symptoms and not treat root causes. 3. A homogenized, regularly shaped metal plate is used as the constraining layer. This one-shot approach is completely incapable of coping with the highly complex, asymmetric, and modal-dense vibration characteristics of HUD freeform lenses. Therefore, there is an urgent need in the art for a new vibration damping solution that is lightweight, miniaturized, and capable of being precisely designed, and that must be capable of non-uniformizing its stiffness and mass distribution to simultaneously and precisely eliminate multiple high frequency formants that cause HUD image dithering. Disclosure of Invention The object of the present invention is to overcome all the above drawbacks of the prior art by providing a composite constraining layer damping vibration attenuation structure with non-uniform stiffness distribution and non-uniform mass distribution that can be precisely designed and tailored to suppress one or more high frequency resonant modes of a curved lens with extremely light weight and extremely small volume while efficiently solving the problem of HUD projected image jitter and blurring fundamentally. Specifically, the invention solves the problems that the vibration damping structure is heavy and low in efficiency and cannot be custom designed for complex vibration modes in the prior art by the metal constraint sheet with the stepped profile and capable of precisely tuning the rigidity gradient and the mass distribution. In order to solve the technical problems, the composite constraint layer damping vibration attenuation structure for a curved mirror provided by the invention comprises: a curved lens; a viscoelastic material layer applied on the back of the curved lens, and A metal constraining sheet in conforming engagement with the layer of viscoelastic material, the metal constraining sheet being configured to have both a predetermined stiffness profile and a predetermined mass profile; The metal constraint sheet is provided with a profile plane limiting the cross-section profile of the metal constraint sheet and a longitudinal extension direction perpendicular to the profile plane, wherein in the profile plane, the cross-section profile of the metal constraint sheet is a continuous stepped profile formed by alternately connecting a plurality of plate sections, the stepped profile is composed of a pluralit