Thermal Head Energization Timing Control via Encoder Pulses

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Solution Overview

Problem

Existing printing apparatuses using thermal heads struggle to dynamically adjust energization timing based on print resolution, leading to inefficiencies and potential printing errors due to fixed timing determined by stepping motors.

Innovation Solution

A printing apparatus equipped with a DC motor, encoder, and processor that measures encoder pulses to adjust energization timing and duration of the thermal head, allowing for flexible control of energization based on print resolution, rotational speed, and medium type, thereby optimizing printing performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a stepping motor is used to drive the transport roller, then the paper feed amount can be precisely controlled per step, but the energization timing for the thermal head becomes fixed and cannot be dynamically adjusted according to print resolution

Engineering Contradiction:

Improvepaper feed amount control precisionVSAvoidenergization timing adjustability

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent replaces the stepping motor (mechanical system with fixed step positions) with a DC motor driven by pulse signals (electrical control system). This substitution allows the transport roller to be driven by variable frequency pulses, enabling dynamic adjustment of paper feed speed and timing. The encoder provides precise position feedback, replacing the mechanical step positioning with an electrical control mechanism that can adapt to different print resolutions.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces dynamic control by using a DC motor with pulse width modulation (PWM) or frequency control, allowing the rotation speed and position of the transport roller to be continuously adjusted. The energization timing of the thermal head is dynamically synchronized with the paper position by counting encoder pulses, enabling adaptive timing adjustment based on actual paper feed speed and print resolution requirements.

Inventive Principle:

Principle #15Dynamics

2Device complexity

If the energization timing is fixed based on stepping motor steps, then the control system is simple, but printing errors may occur when changing print resolution

Engineering Contradiction:

Improvecontrol system complexityVSAvoidprinting accuracy

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent employs feedback control by using an encoder to continuously monitor the actual position and speed of the transport roller. The controller counts encoder pulses to determine paper feed distance and adjusts the thermal head energization timing based on real-time feedback. This closed-loop control ensures accurate printing regardless of variations in paper feed speed or resolution changes, significantly improving printing reliability.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system automatically adjusts energization timing based on encoder feedback without requiring manual intervention or complex preset configurations. The controller self-regulates the timing by counting pulses and dynamically calculating the optimal energization moment, making the system adaptable to different print resolutions while maintaining simple operation.

Inventive Principle:

Principle #25Self-service

3Adaptability or versatility

If a DC motor with encoder is used instead of a stepping motor, then energization timing can be dynamically adjusted, but the device complexity increases

Engineering Contradiction:

Improveenergization timing flexibilityVSAvoidmotor and control system complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The DC motor system with encoder serves multiple functions: it provides both the driving force for the transport roller and the position feedback through the encoder. The same controller that generates drive pulses also processes encoder feedback and determines energization timing, consolidating multiple functions into a unified control system that reduces overall complexity despite the increased capability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

Enables precise control of thermal head energization, reducing errors and improving printing quality by dynamically adjusting energization timing and duration according to print resolution and medium characteristics, enhancing electrical efficiency and power usage.

Implementation Method 1

an encoder configured to output a first detection pulse in response to a rotation of the DC motor

Methodology Applied

Scientific EffectEncoder pulse output:

Implementation Method 2

a thermal head including a plurality of heating members that generate heat when energized

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS10933657B2Printing apparatus and method of controlling printing apparatus

Publication Date: 2021.03.02 SEIKO EPSON CORP

AI summary

A level change point detection section detects a level change point, at which an output level switches, in a first position detection signal Ens1 generated by an encoder or a second position detection signal obtained by increasing the resolution of the Ens1. Each time a predetermined number of level change points is detected, an energization timing determination section determines the timing, at which the predetermined number of level change points have been detected, to be an energization timing for the thermal head.