Encoder Scale Indefinite Areas for Printhead Timing Adjustment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Inkjet printing apparatuses face challenges in maintaining precise ink droplet placement due to thermal expansion of rotating members, leading to image unevenness and color misalignment when using multiple printheads, as existing sensor configurations cannot accurately detect the connection points of linear encoder scales, resulting in phase differences and alignment errors.
Innovation Solution
A printing apparatus with a rotating member featuring multiple printing areas, a printhead, and a linear encoder scale with slits, where multiple encoder sensors are positioned to detect the slits, and an adjustment unit adjusts the discharge timing using detection results from these sensors, ensuring that the first encoder sensor's results are not used during discharges corresponding to its own indefinite area, thereby avoiding the influence of thermal expansion-induced errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a linear encoder scale is installed on a rotating member to enable precise discharge control, then discharge precision is improved, but thermal expansion of the rotating member causes connection issues and image unevenness
Solution Approach 1:
The encoder scale is divided into multiple sections with at least one indefinite area (connection area) where slits are not formed. This segmentation allows the scale to accommodate thermal expansion of the rotating member while maintaining measurement precision in the defined areas, preventing image unevenness caused by connection issues.
Solution Approach 2:
Different areas of the encoder scale have different properties: some areas have slits for precise position detection while others have indefinite areas without slits to accommodate thermal expansion. This local differentiation allows the scale to simultaneously provide measurement precision and thermal compensation.
2Area of stationary object
If multiple encoder sensors are used to detect the encoder scale, then measurement coverage is improved, but phase differences between sensors cause alignment errors
Solution Approach 1:
The indefinite area acts as an intermediary zone between the encoder sensors, providing a reference point that allows synchronization of timing between multiple sensors without causing phase differences. This mediator enables multi-sensor coverage while maintaining alignment accuracy.
3Stability of the object's composition
If the rotating member diameter is increased to maintain linehead vertical alignment, then alignment stability is improved, but thermal expansion effects are amplified
Solution Approach 1:
The encoder scale parameters are modified to include indefinite areas without slits, changing the physical characteristics of the scale to accommodate thermal expansion. This allows larger rotating members to maintain alignment stability while compensating for thermal expansion effects through the flexible scale design.
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 effectively suppresses image unevenness and color misalignment by stabilizing the discharge timing across multiple printheads, ensuring high-quality image formation on the rotating member and subsequent printing medium.
Implementation Method 1
a linear encoder scale having slits and provided on the rotating member along a rotation direction
Data Source
AI summary
In a printing apparatus, an indefinite area in which slits are not formed is configured in a portion of a linear encoder scale in a rotation direction, and an adjustment unit adjusts the timing of discharge from a printhead with respect to a first printing area out of a plurality of printing areas on a rotating member, without using a detection result of a first encoder sensor, based on a detection result of a second encoder sensor, the first encoder sensor being provided at a position corresponding to the indefinite area during a discharge of printing material with respect to the first printing, and the second encoder sensor being provided at a position that does not correspond to the indefinite area during the discharge of the printing material with respect to the first printing area.