Print Head Calibration via Vernier Scale Alignment
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Solution Overview
Problem
Conventional calibration methods for ink jet printers in mailpiece handling systems are inefficient, requiring trial and error and taking significant time, leading to production downtime due to frequent calibration needs when print heads are replaced.
Innovation Solution
A method and device that utilize a transport system, printer, and controller to align print heads by printing a test pattern and determining a correction value using a vernier scale and main scale, allowing for precise rotation to align print elements with the transport path, eliminating the need for iterative adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional trial and error calibration method is used, then print head alignment can be achieved, but calibration time is excessive and causes production downtime
Solution Approach 1:
The patent applies preliminary action by pre-configuring the vernier scale with predetermined angular positions that correspond to specific correction values. This allows the operator to directly select the appropriate angular position based on measured deviations from the test pattern, eliminating the need for iterative trial and error adjustments. The correction values are calculated in advance and mapped to specific vernier scale positions, enabling direct alignment in a single calibration operation.
Solution Approach 2:
The vernier scale acts as an intermediary device that bridges the measurement of print head deviation and the adjustment of printer rotation. Instead of directly iterating through multiple test patterns and adjustments, the vernier scale provides a direct mapping between measured correction values and the required rotational adjustment. This intermediary mechanism translates complex alignment problems into simple scale readings and corresponding angular positions.
2Reliability
If frequent calibration is performed to maintain image quality, then print quality is maintained, but production downtime increases
Solution Approach 1:
The vernier scale is pre-configured with multiple correction values corresponding to different angular positions, allowing rapid calibration without iterative testing. This preliminary preparation enables calibration to be completed in a single operation, making it feasible to perform frequent calibrations without significant production downtime, thus maintaining image quality consistency while preserving productivity.
Solution Approach 2:
The patent replaces the mechanical iterative adjustment process with a direct measurement and adjustment system using the vernier scale. Instead of repeatedly printing test patterns and manually adjusting rotation, the system uses the vernier scale to directly determine the required correction, substituting a complex mechanical iteration process with a simpler, faster measurement-and-adjustment approach.
3Measurement precision
If multiple iterative adjustments are made to align print heads, then alignment accuracy is achieved, but device complexity and operational difficulty increase
Solution Approach 1:
The vernier scale serves as an intermediary that simplifies the calibration operation by providing a direct visual mapping between measured deviations and required corrections. Instead of performing multiple iterative adjustments and interpreting complex test patterns, the operator simply reads the correction value from the vernier scale and rotates the printer to the corresponding predetermined angular position, making the process intuitive and straightforward.
Solution Approach 2:
The predetermined angular positions on the vernier scale are prepared in advance, with each position corresponding to a specific correction value. This preliminary configuration eliminates the need for complex iterative reasoning during operation, allowing the operator to directly translate the measured deviation into the correct adjustment by selecting the appropriate vernier scale position.
Data Source
AI summary
A printing assembly includes a transport system configured to transport items on a transport path and a printer rotatably disposed on a support. The printer includes a plurality of printing elements disposed sequentially along the transport path. A method of calibrating the printing assembly includes aligning a first reference associated with the printer with a second reference associated with the support, transporting an item on the transport path, printing a pattern on the item using a first printing element and a second printing element, determining a correction value from the pattern, and rotating the printer relative to the support in an amount corresponding to the correction value to substantially align the printing elements with the transport path.