Duplex Printer Sheet Quality Detection with Dual Rejection Thresholds
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Solution Overview
Problem
Existing printing systems face challenges in accurately detecting sheet deformations due to their inability to distinguish between different sheet types, leading to reduced print quality and increased risk of sheet jams, as they apply the same rejection criteria to all sheets without considering specific conditions such as media type or prior processing.
Innovation Solution
The implementation of a dual-sheet quality detection system with separate rejection thresholds for different sheet types, allowing the controller to designate each sheet to either of two detection devices based on its state parameters, enabling tailored rejection criteria without requiring adjustments between sheets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single sheet quality detection device with uniform rejection criteria is used for all sheet types, then the device complexity is reduced, but the measurement precision of sheet deformations deteriorates because the same criteria cannot be attuned to specific sheet conditions
Solution Approach 1:
The detection system is segmented into multiple detection devices (first and second sheet quality detection devices), each equipped with its own rejection criteria. The controller divides the detection task by routing different sheet types to appropriate detection devices based on sheet state parameters, allowing each device to specialize in detecting deformations for specific sheet conditions without requiring complex reconfiguration.
Solution Approach 2:
The system dynamically selects which detection device to use based on the sheet state parameter determined by the controller. This dynamic routing allows the rejection criteria to be adapted to specific sheet types (e.g., glossy vs. matte, different thicknesses) without physically reconfiguring the detection device, maintaining both simplicity and precision.
2Measurement precision
If rejection criteria are adjusted between consecutive sheets to match specific sheet types, then the measurement precision improves, but the productivity deteriorates due to the time delay required for adjustments
Solution Approach 1:
The system performs preliminary classification of sheets by state parameters before detection. By pre-organizing sheets into categories (e.g., simplex vs. duplex, different media types) and pre-configuring multiple detection devices with different rejection criteria, the system eliminates the need for time-consuming adjustments between sheets. The controller simply routes each sheet to the appropriate pre-configured device.
Solution Approach 2:
Instead of adjusting a single detection device, the system uses multiple detection devices that are essentially copies with different pre-configured rejection criteria. This allows simultaneous handling of different sheet types without adjustment delays, as each device is already optimized for its specific sheet type.
3Manufacturing precision
If the print gap is reduced to achieve high print quality, then the manufacturing precision of the printed output improves, but the reliability deteriorates because the printing head becomes more susceptible to sheet deformations and head touches
Solution Approach 1:
The detection system performs preliminary identification of sheet deformations (dog ears, wrinkles, tears) before the sheet reaches the printing head. By detecting and flagging problematic sheets in advance, the system can take preventive actions (such as adjusting transport parameters or alerting the operator) to prevent head touches, thereby maintaining the small print gap needed for high quality while protecting against reliability issues.
Solution Approach 2:
The detection device provides feedback about sheet conditions to the controller, which can then adjust transport parameters or alert operators about potential head touch risks. This feedback loop allows the system to maintain optimal print quality settings while dynamically responding to sheet variations that could cause reliability problems.
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 approach enhances the accuracy of defect detection and maintains high productivity by allowing specific rejection criteria for each sheet type, reducing the likelihood of sheet jams and improving print quality by eliminating the need for operator intervention in threshold adjustments.
Implementation Method 1
a first and a second optical emitter positioned alongside a sheet sensing transport path, such that the optical emitters emit light beams respectively at a first and a second predefined height over the sheet sensing transport path; a sensor assembly for sensing the light beams
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A duplex sheet printer comprising a first and second sheet quality detection device for determining a suitability of a sheet for printing. The first sheet quality detection device applies a first sheet rejection threshold to which sensed sheets are compared, while the second sheet quality detection device applies a second sheet rejection threshold different from the first. The controller designates sheets in the printing system to be sensed by one of the sheet quality detection devices in accordance with the sheet's media type or the sheet being on a simplex or duplex pass. Different rejection criteria are thus applied to the sheets without adjustment of a sheet quality detection device, resulting in high speed printing.