HUD Reflector Mirror Backlash Compensation
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Solution Overview
Problem
HUD devices experience discomfort due to backlash effects in reduction gear mechanisms, causing inconsistent virtual image positioning when passengers attempt to move the display in opposite directions, leading to reduced control over the display position.
Innovation Solution
A controller is implemented in the HUD device that determines the direction of rotation and adds a reverse step angle equal to or greater than the sum of the backlash angle and reference step angle to ensure consistent rotation of the reflector mirror, thereby maintaining intended display position adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the stepper motor is rotated in reverse direction to move the virtual image display position, then the display position can be adjusted, but the backlash effect in the reduction gear mechanism causes the reflector mirror to rotate less than intended or not at all
Solution Approach 1:
The controller performs a preliminary action by adding a reverse step angle (equal to or greater than the backlash angle) to the control step angle before rotating the stepper motor in reverse direction. This preliminary compensation ensures that the reflector mirror rotates by the intended amount despite the backlash effect in the reduction gear mechanism, thereby maintaining rotation accuracy during display position adjustment.
2Reliability
If the controller adds a reverse step angle to compensate for backlash, then the reflector mirror rotation accuracy is improved, but the control system complexity increases
Solution Approach 1:
The controller changes the control parameter (step angle) based on the rotation direction. When rotating in reverse, the controller adds the reverse step angle to compensate for backlash; when rotating in the same direction, no compensation is needed. This parameter adjustment approach improves rotation accuracy without requiring additional hardware components, thereby limiting the increase in control system complexity to software logic only.
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 solution ensures reliable movement of the virtual display position in both same and opposite directions, reducing passenger discomfort by accounting for backlash effects and maintaining accurate control over the display position.
Implementation Method 1
a reflector mirror that reflects the display light from the projector toward the projection member
Data Source
AI summary
A HUD device mounted on a moving body that projects an image on a projection member to virtually display the image includes a projector, a reflector mirror, a stepper motor, a reduction gear mechanism that reduces rotation which is output from the stepper motor and transmitted to the reflector mirror, and a controller that calculates a control step angle for the stepper motor. The controller, when an output direction of the motor according to the control instruction at this determination is the opposite direction as a direction of the rotation of the last time, adds a reverse step angle of the opposite direction, which is equal to or greater than a sum of a reference step angle and a backlash angle of the reduction gear mechanism, to the control step angle.