Inkjet Printer Optical Sensor Sheet Position Detection
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Solution Overview
Problem
Inkjet printers face challenges in accurately detecting the position and size of recording media during image formation, leading to potential ink misalignment and inefficiencies in ink discharge, especially with varying sheet types and sizes.
Innovation Solution
An image forming apparatus equipped with a recording head, an optical sensor, and a control unit that uses the sensor's signal to detect the position of the recording medium by setting a threshold for signal intensity and determining the sheet's presence and boundaries based on a predetermined interval of signal consistency, ensuring precise ink discharge only on the medium.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the optical sensor is used to detect the position of the recording medium, then the detection accuracy is improved, but the reliability is worsened when the recording medium has low reflection rate
Solution Approach 1:
The patent applies preliminary action by detecting the leading end and trailing end of the recording medium before actual image formation. The control unit detects the leading end position first, then performs image formation within the detected range, and finally detects the trailing end position. This preliminary detection ensures that the ink discharge is confined to the actual recording medium area, preventing waste on non-medium areas while maintaining reliable detection even for low reflection rate materials.
Solution Approach 2:
The patent implements feedback by continuously monitoring the optical sensor signals during carriage movement and adjusting the ink discharge control based on detected positions. The control unit uses the optical sensor feedback to determine the exact leading and trailing ends of the recording medium, then adjusts the image formation range accordingly. This feedback mechanism ensures reliable operation across different medium types by adapting the discharge range to actual medium boundaries.
2Loss of substance
If the ink discharge is controlled based on optical sensor signal, then the ink usage efficiency is improved, but the manufacturing precision is worsened due to signal fluctuation
Solution Approach 1:
The patent applies preliminary action by performing position detection before image formation. The control unit detects the leading end position of the recording medium before starting ink discharge, then uses this pre-detected position to establish the image formation range. This preliminary detection eliminates the need for continuous high-precision signal monitoring during discharge, reducing the impact of signal fluctuations while maintaining precise ink placement within the detected boundaries.
Solution Approach 2:
The patent segments the detection process into distinct phases: leading end detection, image formation execution, and trailing end detection. By dividing the operation into these segments, the system can use broader detection criteria for boundary identification without compromising the precision of ink discharge within the established range. The segmentation allows the system to prioritize accurate boundary detection over continuous precision monitoring.
3Adaptability or versatility
If the detection range is extended to cover the entire carriage movement, then the adaptability is improved, but the productivity is worsened due to increased detection time
Solution Approach 1:
The patent extracts only the necessary detection portions from the entire carriage movement range. Instead of detecting positions throughout the full movement range, the system specifically extracts and detects only the leading end and trailing end positions of the recording medium. This selective extraction maintains adaptability to different medium sizes and positions while significantly reducing the detection time and improving productivity by focusing only on critical boundary points.
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 solution enhances the accuracy of sheet detection and ink discharge, preventing misalignment and improving the efficiency of image formation on various types and sizes of recording media, including those with low reflection rates like tracing paper.
Implementation Method 1
an optical sensor to output a signal in response to intensity of reflection of light emitted to the direction of discharging the ink
Data Source
AI summary
An image forming apparatus includes a recording head to discharge ink to a recording medium to form an image thereon, an optical sensor to output a signal in response to intensity of reflection of light emitted to the direction of discharging the ink, a carriage that carries the recording head and the optical sensor, and a control unit to detect the position of the recording medium based on the signal output by the optical sensor and control the recording head to discharge the ink only onto the position of the recording medium, wherein the control unit acquires a value according to the signal output by the optical sensor in response to the movement of the carriage and detects the position of the recording medium when a predetermined relation between the value and a threshold continues at least for a predetermined interval in the movement of the carriage.