Head-Up Display Mirror Drive With Gearless Axial Torque Transmission
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Solution Overview
Problem
Conventional head-up display devices are not adequately downsized due to complex torque transmission mechanisms, which can be simplified by reducing the number of components and eliminating gears to achieve compactness and improved responsiveness.
Innovation Solution
A head-up display device configuration featuring a rotatable mirror with a reflecting surface, a motor with an output shaft aligned with the input shaft, a transmission member with a cylindrical fitting portion and coupling portion to transmit torque, and a first spring that biases the transmission member to bring the mirror closer to the output shaft, reducing the axial size and eliminating the need for gears.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a complex torque transmission mechanism including gears is used, then the mirror can be reliably rotated, but the device size increases and responsiveness decreases
Solution Approach 1:
The patent extracts and eliminates the gear transmission mechanism from the torque transmission path. The motor's output shaft is directly aligned with the mirror's input shaft, removing intermediate gears and reducing the number of components. This extraction of unnecessary elements achieves downsizing while maintaining reliable torque transmission through direct mechanical coupling.
Solution Approach 2:
The patent merges the motor output shaft and mirror input shaft into a collinear configuration, where the motor's output shaft extends along the same axis as the mirror's input shaft. This merging of components eliminates the need for gear trains and reduces the overall device volume while ensuring reliable torque transmission through direct alignment.
2Device complexity
If gears are eliminated to downsize the device, then device complexity reduces, but torque transmission reliability may worsen
Solution Approach 1:
The motor output shaft and mirror input shaft are merged into a direct collinear connection, eliminating gears and reducing complexity. The transmission member with cylindrical fitting portion provides direct torque transmission from motor to mirror, simplifying the mechanism while maintaining reliability through direct mechanical coupling.
Solution Approach 2:
A transmission member acts as an intermediary between the motor and mirror, providing direct torque transmission without gears. This intermediary component with cylindrical fitting portions enables reliable torque transmission while maintaining a simple, gear-free structure that reduces overall device complexity.
3Volume of moving object
If the axial distance between motor and mirror is reduced, then device volume decreases, but the mirror may deform due to increased biasing force
Solution Approach 1:
The biasing function is segmented from the mirror structure and assigned to a dedicated first spring component positioned between the holding member and transmission member. This segmentation allows the spring to provide axial biasing force for compactness while the mirror structure remains separate and undisturbed, preventing deformation of the reflecting surface.
Solution Approach 2:
The first spring acts as an intermediary that provides axial biasing force to the transmission member without directly contacting the mirror. This intermediary spring enables reduced axial distance for downsizing while isolating the mirror from deformation-causing forces, maintaining reflecting surface stability.
4Speed
If a direct axial connection between motor and mirror is used, then responsiveness improves, but the mirror structure becomes more complex
Solution Approach 1:
The motor output shaft and mirror input shaft are merged into a direct collinear configuration, enabling immediate torque transmission and fast mirror rotation response. This merging eliminates intermediate transmission stages, improving responsiveness while the transmission member with cylindrical fitting portions maintains structural simplicity.
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 achieves downsizing of the head-up display device, enhances responsiveness, and minimizes deformation of the mirror's reflecting surface by using a biasing force that does not directly act on the mirror, thereby maintaining the integrity of the reflecting surface.
Implementation Method 1
a first spring interposed between the holding member and the transmission member, the first spring being configured to impart, to the transmission member, a biasing force oriented to bring the mirror close to the output shaft along an axial direction of the input shaft
Implementation Method 2
a transmission member having a cylindrical fitting portion to which the input shaft is press-fitted and a coupling portion coupled with the output shaft, the transmission member being configured to transmit output torque of the motor from the output shaft to the input shaft
Implementation Method 3
a rotatable mirror having a reflecting surface configured to reflect the display light toward a reflecting portion arranged in front of a driver
Data Source
AI summary
A head-up display device includes an image display device that outputs display light of an image; a mirror having a reflecting surface that reflects the display light toward a reflecting portion, and an input shaft; a motor that has an output shaft located on an extended line of the input shaft, and rotates the output shaft; a transmission member that has a cylindrical fitting portion to which the input shaft is press-fitted and a coupling portion coupled with the output shaft and transmitting output torque of the motor from the output shaft to the input shaft; a holding member that holds the motor; and a first spring that is interposed between the holding member and the transmission member, and imparts, to the transmission member, a biasing force oriented to bring the mirror close to the output shaft.