Projection Device Anti-Vibration Mounting for Head-Up Displays
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Solution Overview
Problem
Conventional head-up display devices experience image blur due to external vibrations from mobile objects, such as vehicles, caused by low resonant frequencies of the spring structure supporting the mirror unit, which leads to unstable amplitude and reduced display image quality, especially when trying to achieve a wider angle of view.
Innovation Solution
The projection device is attached to a mobile object with anti-vibration members that have a resonant frequency above 100 Hz, ensuring that the direction of vibration caused by the object is perpendicular to the reflective surface of the optical scanning unit, thereby reducing vibration transmission and maintaining image stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the rigidity of the spring structure supporting the mirror unit is lowered to achieve a wider angle of view, then the angle of view of the optical scanning device is improved, but the resonant frequency of the spring structure decreases causing image blur due to vibration resonance
Solution Approach 1:
The patent introduces a vibration counteract unit as an intermediary component that generates counter-vibrations to cancel out the vibrations caused by lowering the spring structure rigidity. This mediator allows the system to maintain both the wide angle of view (through low rigidity spring structure) and image stability (through active vibration cancellation)
Solution Approach 2:
The patent changes the resonant frequency parameter of the vibration counteract unit to be higher than that of the spring structure. By adjusting this parameter relationship, the system can effectively counteract vibrations across the operating frequency range while maintaining the low rigidity configuration for wide angle of view
2Object-affected harmful factors
If a damper with high damping ratio is used to damp external vibration, then vibration damping is improved, but resonance amplification during damper resonance increases causing larger displacement of the optical unit
Solution Approach 1:
The patent uses mechanical vibration principles by generating counter-vibrations through the vibration counteract unit. Instead of passively damping vibrations, the system actively generates opposing vibrations to cancel out harmful external vibrations, avoiding the resonance amplification problem inherent in high-damping ratio dampers
Solution Approach 2:
The patent converts the harmful external vibrations into beneficial counter-vibrations by using the vibration counteract unit to generate oscillations that are 180 degrees out of phase with the external vibrations. This transforms the harmful vibration energy into a beneficial cancellation effect
3Object-affected harmful factors
If the resonant frequency of the damper is designed within a low frequency band to damp vibration, then damping effectiveness is improved, but the resonance amplification during resonance increases causing larger displacement
Solution Approach 1:
The patent applies mechanical vibration by generating active counter-vibrations from the vibration counteract unit. This approach addresses low frequency vibrations directly through phase-opposed oscillations rather than relying on passive damping, thereby avoiding resonance amplification while maintaining effectiveness against low frequency disturbances
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
This configuration effectively reduces vibration transmission to the optical scanning device, allowing for a wider angle of view without image blur, even when the spring structure's rigidity is lowered to support wider rotation of the mirror unit.
Implementation Method 1
a vibration counteract unit configured to generate vibrations to counteract vibrations transmitted from the mobile object
Implementation Method 2
the resonant frequency of the spring structure is lower than the resonant frequency of the vibration counteract unit
Data Source
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AI summary
According to an embodiment, a projection device (10) includes: a light source (22, 23, 24); an optical scanning unit (28) that includes a base unit (35), a driver (36) fixed to the base unit (35), and a reflective unit (34) supported by the driver (36) and that drives the reflective unit (34) to scan light from the light source (22, 23, 24); and a scanned unit (29) configured to be scanned with the light from the optical scanning unit (28) so that a projection image is formed on the scanned unit (29). The projection device (10) further includes an attachment unit (41) for attaching the projection device (10) to a setting unit (44) of a setting object on which the projection device (10) is set. The attachment unit (41) attaches the projection device (10) to the setting unit (44) such that a direction in which vibration caused by the setting object is equal to or smaller than a predetermined value and a reflective surface of the reflective unit (34) are approximately perpendicular to each other.