Movable Mirror Timing Correction for Image Distortion
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Solution Overview
Problem
Existing image forming apparatuses face challenges in accurately estimating the deflection angle of a movable mirror, leading to image distortion due to time delays in driving and sensor signals caused by noise.
Innovation Solution
The image forming apparatus includes a light emitting device, a movable mirror, actuators for swinging the mirror, a reference signal output portion for estimating deflection angles, and a correction portion that adjusts the timing of the reference signals based on imaging information to correct for signal delays and ensure accurate image projection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a stress sensor is used to estimate the deflection angle of the movable mirror, then the deflection angle can be measured, but time delay occurs in the sensor signal due to noise, making it difficult to accurately estimate the deflection angle
Solution Approach 1:
The patent introduces an imaging apparatus as an intermediary to capture the actual position of the projected image. This captured image serves as a mediator between the mirror deflection and the control system, providing direct feedback about the actual deflection angle without suffering from the time delay and noise issues of stress sensors. The imaging apparatus captures the image at the projection destination, and this captured information is then used to correct the timing of reference signals.
Solution Approach 2:
The patent implements a feedback mechanism where the imaging apparatus continuously monitors the actual position of the projected image, and this feedback information is used to correct the timing of reference signals generated by the reference signal output portion. The correction portion uses the captured image data to adjust the timing of reference signals, creating a closed-loop feedback system that compensates for time delays and ensures accurate deflection angle estimation.
2Speed
If the movable mirror is resonantly driven to increase deflection angle and scanning range, then the scanning range is increased, but image distortion occurs due to shift in irradiation timing between advancing path and returning path
Solution Approach 1:
The patent uses the imaging apparatus to capture the actual position of the projected image during resonant driving of the movable mirror. The correction portion then uses this captured image information to correct the timing of reference signals for both the advancing path and returning path of the mirror swing. This feedback mechanism ensures that even during high-speed resonant driving, the irradiation timing is accurately adjusted to prevent image distortion.
Solution Approach 2:
The patent performs preliminary calibration by capturing images at different deflection angles and storing the correspondence between captured image positions and deflection angles in advance. This pre-established mapping relationship is then used during actual operation to correct timing of reference signals, allowing the system to compensate for timing shifts without real-time complex calculations, thus maintaining image accuracy during high-speed scanning.
Data Source
AI summary
An image forming apparatus includes a light emitting device that emits light, a movable mirror that reflects the light emitted from the light emitting device, a first actuator that causes the movable mirror to swing about a first axis, a first reference signal output portion that outputs a first reference signal by estimating a point in time when a deflection angle of the movable mirror about the first axis becomes equal to a first reference angle, a light emission controller that causes the light emitting device to emit the light based on the first reference signal output from the first reference signal output portion, an imaging apparatus that images the light reflected by the movable mirror, and a correction portion that corrects a timing of the first reference signal output by the first reference signal output portion based on imaging information acquired by the imaging apparatus.