Image Forming Apparatus Speed Control for Ink Alignment
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Solution Overview
Problem
Conventional image forming apparatuses experience deterioration in image quality due to misalignment of ink drop landing positions during acceleration and deceleration, limiting the precision of image formation and the ability to downsize the apparatus while maintaining high-quality output.
Innovation Solution
The apparatus incorporates a recording unit, conveyance mechanism, position detecting unit, image forming control unit, and conveyance control unit, which controls the recording unit's speed and position to ensure symmetrical speed trajectories during acceleration and deceleration, allowing image formation during these phases while maintaining precise ink drop alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If image forming operation is performed during acceleration and deceleration of the recording unit, then the conveyance path length is shortened and apparatus size is reduced, but misalignment of ink drop landing positions occurs and image quality deteriorates
Solution Approach 1:
The patent applies asymmetry by making the deceleration distance longer than the acceleration distance. Specifically, the deceleration distance is set to be longer than the acceleration distance by a predetermined distance corresponding to the sub-scanning direction conveyance amount. This asymmetric design allows the recording unit to decelerate more gradually, ensuring that ink drops are deposited at correct positions even during deceleration, while still allowing acceleration to occur within the image forming area to shorten the overall conveyance path.
Solution Approach 2:
The patent changes the parameter of conveyance speed trajectory by controlling the recording unit to accelerate and decelerate at different rates and over different distances. The acceleration and deceleration are controlled to have different characteristics, with deceleration extending beyond the image forming area. This parameter change enables the system to maintain precision during speed transitions while achieving path shortening.
2Manufacturing precision
If the recording unit is moved at constant speed during image forming, then uniform image quality is achieved, but the conveyance path must be extended to allow acceleration and deceleration zones
Solution Approach 1:
The patent introduces asymmetry in the speed profile by allowing acceleration within the image forming area while extending deceleration beyond it. This asymmetric speed control enables the recording unit to reach operating speed quickly during acceleration, maintain constant speed for most of the image forming process, and then extend the deceleration phase to ensure precise stopping, thereby reducing overall path length while maintaining image uniformity.
Solution Approach 2:
The patent applies dynamics by transitioning from static constant-speed operation to dynamic speed control where the recording unit accelerates and decelerates during the image forming process. The speed is dynamically adjusted with acceleration occurring within the image forming area and deceleration extending beyond it, allowing the system to adapt speed profiles to optimize both path length and image quality.
3Volume of stationary object
If the recording unit accelerates and decelerates within the image forming area, then apparatus size is reduced, but control precision of ink landing positions becomes insufficient
Solution Approach 1:
The patent uses asymmetry to resolve the precision issue by making the deceleration distance longer than the acceleration distance. The extended deceleration phase beyond the image forming area provides additional control margin, ensuring that the recording unit can be precisely positioned at the end of the image forming area. This asymmetric design compensates for the reduced apparatus size while maintaining landing position precision.
Solution Approach 2:
The patent applies preliminary action by extending the deceleration phase beyond the image forming area. This allows the recording unit to begin decelerating before reaching the end of the image forming area, ensuring that speed is reduced to appropriate levels for precise positioning. The preliminary deceleration action guarantees accurate landing positions even though the overall apparatus size is reduced.
Data Source
AI summary
An image forming apparatus includes a conveyance control unit that controls conveyance of a recording unit. The conveyance control unit switches a conveyance direction of the recording unit at return points on both sides of a scanning direction to reciprocate the recording unit, and controls a speed of the recording unit to a target speed until the recording unit reaches a control changeover point from the return point upstream in the conveyance direction. The target speed is set to be symmetrical in a zone in which the recording unit is shifted to a constant speed state from a start point of an image forming area and in a zone in which the recording unit reaches the end point of the image forming area from a deceleration start point.