Thermal Head Clock Phasing for Low-EMI Data Input
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Solution Overview
Problem
Thermal printers with a thermal head configuration where heating elements are divided into blocks face issues with 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 each block using different first clock signals, generated with phase-shifted second clock signals, to synchronize the drive data supply with the thermal head, minimizing common-mode noise by ensuring the clock signals have a phase difference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If drive data is input in parallel to each block using the same clock signal, then the data input speed is improved, but common-mode noise increases causing electromagnetic interference
Solution Approach 1:
The patent divides the heating elements into multiple blocks and assigns different clock signals to each block, segmenting the data input process. This allows parallel data input to continue while distributing the clock signals across different phases, thereby maintaining high data input speed while reducing simultaneous switching noise and common-mode electromagnetic interference.
2Object-generated harmful factors
If multiple clock signals with phase differences are used, then common-mode noise is reduced, but the system complexity increases
Solution Approach 1:
The patent introduces a clock signal generation unit as an intermediary component that automatically generates multiple clock signals with predetermined phase differences. This intermediary handles the complexity of phase-shifted clock signal generation internally, allowing the rest of the system to benefit from reduced common-mode noise without requiring complex external clock distribution networks or manual phase adjustment circuits.
Data Source
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.