Pulse Timing Correction for Encoder-Induced Printing Unevenness
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Solution Overview
Problem
Existing image forming apparatuses with encoders often experience periodic printing unevenness, which lowers image quality.
Innovation Solution
A pulse generator is introduced, comprising a position calculating part, an adjusting amount calculating part, and a timing adjusting part. This generator calculates the driving object position, adjusts the timing pulse output based on predetermined adjusting amounts, and corrects the output timing to suppress periodic printing unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a timing pulse is generated based on detection signal from an encoder to control ink discharging timing, then the image forming apparatus can detect carriage position and speed for controlling ink ejection, but periodic printing unevenness is generated and image quality is lowered
Solution Approach 1:
The patent introduces an intermediary calculation process between the encoder detection signal and the timing pulse generation. The position calculation unit computes carriage position from encoder signals, the adjustment amount calculation unit determines correction values based on periodic fluctuations, and the timing adjustment unit applies these corrections to generate adjusted timing pulses. This intermediary processing chain mediates between the raw detection data and the final control signals, eliminating periodic printing unevenness while maintaining detection precision.
Solution Approach 2:
The patent changes the timing parameter of the discharging pulse by calculating adjustment amounts based on detected periodic fluctuations. The timing adjustment unit modifies the discharge timing parameter dynamically according to the calculated adjustment amounts, which compensate for periodic position deviations caused by mechanical fluctuations in the carriage movement system.
2Speed
If the carriage motor rotates to move the carriage, then the carriage can be positioned for ink discharge, but periodic speed fluctuations occur causing printing unevenness
Solution Approach 1:
The patent implements a feedback mechanism where the encoder continuously detects carriage position, the position calculation unit computes actual position, the adjustment amount calculation unit compares this with expected position to detect periodic fluctuations, and the timing adjustment unit applies corrections based on this feedback. This closed-loop feedback system compensates for periodic speed variations caused by motor rotation characteristics, maintaining printing uniformity.
Data Source
AI summary
A pulse generator includes: a position calculating part configured to calculate a position of a driving object, based on a detection signal of a detection signal outputting part; an adjusting amount calculating part configured to calculate at least one adjusting amount previously set so that a value of the at least one adjusting amount is periodically changed with respect to the position of the driving object; and a timing adjusting part configured to determine an output timing, at which the timing pulse is to be output, based on the at least one adjusting amount.