Inkjet Drive Roller Speed Stabilization via Optical Timing
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Solution Overview
Problem
Ink jet recording apparatuses face challenges in stabilizing the turning speed of the conveyor belt and ink discharge timing due to individual differences in the outer diameter of driven rollers and inaccuracies in encoder mounting, leading to image elongation or contraction issues.
Innovation Solution
An ink jet recording apparatus with a control unit that includes a storage for outer diameter information, a notch filter to attenuate specific frequency components of pulse signals from the encoder, and a discharge timing controller to adjust ink discharge timing based on these signals, ensuring stable conveyor belt speed and ink discharge timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the angular velocity of the driven roller is detected by an encoder to control ink discharge timing, then the ink discharge timing can be determined, but when the outer diameter of the driven roller varies, the detected angular velocity does not accurately reflect the conveyor belt speed, causing image elongation or contraction
Solution Approach 1:
The patent replaces the mechanical encoder detection system with an optical measurement system. A light source and light receiver are positioned to detect the outer peripheral surface of the driven roller, using optical timing rather than mechanical encoders to determine conveyor belt speed and ink discharge timing, thereby eliminating errors from encoder mounting inaccuracies and roller diameter variations
Solution Approach 2:
The patent changes the detection parameter from angular velocity (which is affected by roller diameter) to the timing of light reception as the roller rotates. By measuring the rotation period of the driven roller through optical detection of its outer peripheral surface and calculating speed based on this period, the system achieves accurate conveyor belt speed measurement independent of roller diameter variations
2Manufacturing precision
If the driven roller is manufactured with a perfectly circular cross-section, then the actual radius remains constant and angular velocity detection is accurate, but manufacturing imperfections cause the roller to shake and the actual radius to vary, leading to detection errors
Solution Approach 1:
The patent replaces the mechanical encoder system that directly measures roller rotation with an optical system that measures the timing of light reception as the roller surface passes. This substitution eliminates the problem of encoder mounting inaccuracies and makes the measurement independent of roller circularity imperfections by focusing on the periodic nature of roller rotation rather than precise angular position
Solution Approach 2:
The patent implements a feedback mechanism where the light reception timing is continuously monitored to determine the rotation period of the driven roller. This feedback loop allows the system to adapt to variations in roller radius and circularity, using the actual measured rotation characteristics to control ink discharge timing accurately
3Ease of manufacture
If the pulse plate center is mounted to coincide with the rotary shaft, then the encoder accurately detects angular velocity, but mounting inaccuracies cause the center to be offset, resulting in detection errors
Solution Approach 1:
The patent replaces the encoder-pulse plate mechanical system with an optical detection system that observes the driven roller's outer peripheral surface directly. This eliminates the pulse plate and its mounting alignment requirements entirely, achieving accurate rotation timing measurement without any mounting precision constraints
Solution Approach 2:
The patent extracts and removes the pulse plate component from the detection system. By eliminating the pulse plate, the system removes the source of mounting alignment errors, using only the driven roller itself as the reference for rotation timing through optical detection of its outer peripheral surface
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
The solution effectively stabilizes the conveyor belt speed and ink discharge timing, even with variations in driven roller diameters and encoder accuracy issues, preventing image elongation or contraction.
Implementation Method 1
a filter that attenuates frequency components of multiple frequencies, using a frequency corresponding to a pulse number of pulse signals output from the encoder during one turn of the driven roller as a target frequency
Data Source
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AI summary
An ink jet recording apparatus (1) is provided with a conveying unit (27), a drive roller controller (501) and a discharge timing controller (502) . The drive roller controller (501) controls a rotation speed of a drive roller (271) based on pulse signals output by an encoder (277) and corresponding to an angular velocity of a driven roller (275) and an actual outer diameter of the driven roller (275) . The discharge timing controller (502) controls an ink discharge timing based on signals obtained by attenuating multiple frequency components of a target frequency corresponding to a pulse number of the pulse signals output from the encoder (277) during one turn of the driven roller (275) in the pulse signals and an actual outer diameter of the driven roller (275) .