Thermal Head Clock Phasing for Low-EMI High-Speed Printing
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Solution Overview
Problem
Thermal printers with thermal heads having multiple heating elements experience common-mode noise due to synchronized drive data input, leading to electromagnetic interference (EMI).
Innovation Solution
The thermal printer employs a configuration where drive data is input in parallel to multiple blocks of heating elements using different clock signals with phase shifts, reducing common-mode noise by minimizing power supply current fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If drive data for multiple blocks is input in parallel using the same clock signal, then the printing speed and productivity are improved, but common-mode noise increases causing electromagnetic interference
Solution Approach 1:
The patent divides the heating elements into multiple blocks (first block, second block, etc.) and assigns different clock signals to each block. This segmentation allows parallel driving of multiple blocks while reducing common-mode noise through phase differences between clock signals, thus resolving the contradiction between high-speed printing and EMI reduction.
Solution Approach 2:
The patent introduces dynamic phase shifting to clock signals supplied to different blocks. By making the clock signals have different phases rather than being identical, the system dynamically reduces common-mode noise while maintaining parallel operation capability, enabling both high productivity and low EMI.
2Productivity
If drive data is input in parallel to increase printing speed, then productivity is improved, but power supply current fluctuations increase
Solution Approach 1:
The patent segments the heating elements into multiple blocks driven by different clock signals with phase differences. This segmentation distributes the current draw over time, reducing simultaneous current fluctuations and improving power supply stability while maintaining parallel operation for high-speed printing.
Solution Approach 2:
The patent uses periodic clock signals with different phases for different blocks. This periodic action with phase distribution spreads out the current consumption peaks, reducing overall power supply current fluctuations while enabling parallel drive operation for increased printing speed.
Data Source
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AI summary
A thermal printer includes a thermal head, a drive data generation unit, a clock generation unit, and a drive data supply unit. The thermal head is configured such that a large number of heating elements divided into a plurality of blocks are mounted thereon, and is configured to input drive data for driving the large number of heating elements to the plurality of blocks in parallel in synchronization with a plurality of different first clock signals. The drive data generation unit is configured to generate a plurality of pieces of drive data for each of the plurality of blocks from print data and to output the plurality of pieces of drive data in synchronization with a plurality of second clock signals. The clock generation unit is configured to generate a plurality of clock signals whose phases are shifted from each other. The drive data supply unit is configured to take in the plurality of pieces of drive data, which are output from the drive data generation unit, in synchronization with the plurality of second clock signals and to supply the plurality of pieces of drive data to the thermal head in synchronization with the plurality of first clock signals.(Figure 2)