Stepping Motor Micro-Step Positioning for Head-Up Display Stability
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Solution Overview
Problem
Stepping motors in head-up display devices often cause unexpected shifts in the displayed image when the user attempts to stop the adjustment, leading to a sense of incongruity due to the motor's holding torque and unstable excitation positions.
Innovation Solution
A display device with a stepping motor driven in micro-step mode, including rotational position specifying means and movement control to guide the rotor to a closer stable excitation position when a stop instruction is received, reducing the movement amount of the displayed image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the stepping motor is operated according to user operation through an adjustment switch, then the displayed image position can be adjusted, but the displayed image may shift in an unexpected direction when the user performs an off operation
Solution Approach 1:
The control unit determines the rotational direction of the rotor before the off operation is completed and prepositions the rotor to a stable excitation position in that direction. This preliminary action ensures that when the off operation completes, the rotor is already positioned stably, preventing unexpected image shifts.
Solution Approach 2:
The control unit continuously monitors the rotational position of the rotor and the state of the adjustment switch. Based on this feedback, it dynamically adjusts the rotor position to maintain stability. When the switch is released, the system uses feedback about the current rotational direction to determine the appropriate stable excitation position to target.
2Reliability
If the rotor is constantly forcibly moved to a stable excitation position when off operation is performed, then the image position stability is improved, but the movement amount of the displayed image increases causing user incongruity
Solution Approach 1:
Instead of always moving the rotor to a stable excitation position regardless of current state, the control unit applies stable excitation positioning only when necessary - specifically when the rotor is not already at a stable position. The movement amount is localized to the minimum required to achieve stability, rather than a fixed large movement.
Solution Approach 2:
The control unit changes the excitation parameter dynamically based on the rotor's current position and the adjustment switch state. When the switch is pressed, the system allows continuous rotation; when released, it transitions to a stable excitation mode but only moves the rotor a minimal amount necessary to reach the nearest stable position in the current rotational direction.
3Stability of the object's composition
If the stepping motor generates holding torque in non-excitation state, then the rotor stabilizes at iron teeth positions, but the displayed image may shift when off operation is not performed at stable excitation position
Solution Approach 1:
Before the off operation completes, the control unit performs a preliminary action by determining the rotational direction and moving the rotor to a stable excitation position in that direction. This ensures that when the holding torque takes effect at the end of the off operation, the rotor is already at a stable position, preventing image shifts.
Solution Approach 2:
The control unit acts as an intermediary between the user's off operation and the rotor's final position. It mediates the transition by introducing a stable excitation phase that bridges the gap between the user's release action and the rotor's natural stabilization, ensuring the rotor ends at a predictable stable position rather than an unpredictable intermediate position.
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 minimizes the movement of the displayed image during stop instructions, thereby reducing user incongruity and ensuring smoother adjustment processes.
Implementation Method 1
When being in a non-excitation state, the stepping motor generates a holding torque in view of its structure, and an N-pole and an S-pole of a rotor are drawn to the closest iron teeth among plural iron teeth of a stator and are stabilized in a state of facing the iron teeth
Data Source
AI summary
The purpose of the present invention is to cut down the travel distance of a display image on receiving a stop instruction intended for a stepping motor and thereby reduce a feeling of strangeness perceived by a user. A display device allows a user to view the image displayed on a display at a prescribed display position. The display device comprises: a stepping motor having a rotor including a magnet and driven by a micro-step drive method; a reflector which moves in accordance with the rotation of the rotor in the stepping motor so as to move the display position; and a motor control device. The motor control device identifies a rotational position of the rotor between adjacent stable excitation positions, and moves the rotor to reach the closer of the stable excitation positions on the basis of the identified rotational position on receiving a stop instruction intended for the stepping motor.