Buffer Unit for Variable Data Printing Defect Management
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Solution Overview
Problem
Printing systems face delays and inefficiencies due to the time-consuming process of defect detection in variable data printing, leading to operator intervention, wastage of materials, and printer downtime, as they struggle to maintain the order and quality of printed images.
Innovation Solution
A system comprising a measurement device, buffer unit, and controller that inspects printed images and controls substrate movement, allowing defective images to be re-printed without interrupting the process and maintaining the original order, using a buffer unit to hold substrates until defects are confirmed, thereby preventing defective images from reaching the output stack.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If defect detection is performed after printing, then printing speed is improved, but defective images cannot be prevented from reaching the output stack
Solution Approach 1:
The buffer unit holds substrates in a queue before they reach the output stack, allowing defect detection to occur after printing but before final output. This preliminary holding action enables defective substrates to be identified and removed while non-defective ones are released, resolving the contradiction by maintaining both high printing speed and reliable defect prevention.
2Measurement precision
If substrates are held in buffer until defect detection is complete, then defect detection accuracy is improved, but printing productivity decreases
Solution Approach 1:
The buffer unit selectively holds only those substrates that require defect detection review, while allowing non-defective substrates to pass through to the output stack without delay. This partial holding action maintains high productivity for good substrates while ensuring accurate defect detection for substrates that need inspection.
Solution Approach 2:
The buffer unit acts as an intermediary between the printing system and the output stack, decoupling the printing speed from the defect detection speed. This intermediary buffer allows the printing system to operate at high speed while substrates are held for inspection at a slower pace, resolving the contradiction between detection accuracy and productivity.
3Manufacturing precision
If the print job is interrupted to re-print defective images, then manufacturing precision is improved, but loss of time increases
Solution Approach 1:
The buffer unit extracts defective substrates from the production flow and holds them separately, allowing the printing system to continue operating without interruption. Non-defective substrates are released to the output stack while defective ones are identified for re-printing, eliminating printer downtime while maintaining high image quality standards.
Solution Approach 2:
The printing system maintains continuous operation by using the buffer unit to handle defect detection and sorting without interrupting the printing process. The printing mechanism continues to print images continuously while the buffer manages the separation of defective and non-defective substrates, ensuring both manufacturing precision and continuous production.
Data Source
AI summary
Certain examples described herein relate to a buffer unit for a printing system. In certain cases, a measurement device is used to obtain measurement data representing an optical property of a printed image on a substrate. A buffer unit receives the substrate downstream of the measurement device and places the substrate in a queue. In certain cases, a controller determines, based on the measurement data, whether the printed image comprises a defect. Responsive to determining that the printed image does not comprise a defect, the controller causes the substrate to be moved from the buffer unit to an output stack. Responsive to determining that the printed image comprises a defect, the controller causes the substrate to not be moved to the output stack.