Thermal Printhead Capacitor Switching for Accurate Resistance Sensing
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Solution Overview
Problem
Conventional thermal printheads face challenges in accurately measuring the resistance value of heating resistor portions due to the influence of capacitors, leading to incorrect measurements and potential delays in switching between printing and measurement modes.
Innovation Solution
The thermal printhead incorporates a switch section electrically connected in series with a capacitor and a resistor, allowing for precise control of current flow and preventing capacitors from energizing heating resistor portions during resistance value measurements, while also utilizing multiple capacitors in parallel to reduce thickness and prevent noise generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a capacitor is electrically connected in parallel to the heating resistor portions to suppress noise, then noise resistance is improved, but the capacitor may remain charged and cause incorrect resistance measurements
Solution Approach 1:
The patent applies dynamics by making the connection state of the capacitor changeable through a switch section. The capacitor is dynamically connected to the heating resistor portions during printing operations to suppress noise, and dynamically disconnected during resistance measurements to ensure accurate readings. This dynamic switching resolves the contradiction between noise suppression and measurement accuracy.
Solution Approach 2:
The patent implements periodic action through alternating between printing operations and resistance value measurements. During printing periods, the capacitor remains connected to suppress noise. During measurement periods, the capacitor is disconnected to ensure accurate resistance readings. This periodic switching between operational modes resolves the contradiction between noise resistance and measurement precision.
2Reliability
If the resistance value of heating resistor portions is measured to check life status, then reliability monitoring is improved, but the measurement may be delayed due to capacitor discharge time
Solution Approach 1:
The patent applies preliminary action by providing a discharge path for the capacitor that is prepared in advance. The discharge path includes a resistor and switch section that can immediately begin discharging the capacitor when switching from printing to measurement mode, eliminating the need to wait for natural discharge and reducing the time loss associated with mode switching.
Solution Approach 2:
The patent uses an intermediary resistor as a discharge path for the capacitor. This intermediary component provides a controlled route for dissipating capacitor charge, enabling faster and more reliable transitions between printing and measurement modes without compromising the integrity of the measurement system.
3Volume of moving object
If multiple capacitors are connected in parallel to reduce thickness, then compactness is improved, but the complexity of controlling charge discharge increases
Solution Approach 1:
The patent applies segmentation by dividing the capacitor system into multiple parallel-connected capacitors. This segmentation allows each capacitor to be smaller and thinner, reducing the overall printhead thickness while maintaining the necessary capacitance value for noise suppression during printing operations.
Solution Approach 2:
The patent implements multi-functionality by using a single switch section that controls the discharge path for all parallel-connected capacitors simultaneously. This universal control mechanism manages the charge discharge of multiple capacitors through one unified system, avoiding the need for separate control circuits for each capacitor and thereby reducing overall complexity.
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
This configuration enables accurate measurement of resistance values, reduces the time taken to switch between printing and measurement modes, and minimizes noise interference, enhancing the overall performance and reliability of the thermal printhead.
Implementation Method 1
A conventional thermal printhead may have a plurality of heating resistor portions arranged along a primary scanning direction. Printing on a print medium is performed by transferring the heat generated at the heating resistor portions to the print medium.
Data Source
AI summary
A thermal printhead includes a plurality of heating resistor portions, a first capacitor, a switch section, and a first resistor. The heating resistor portions are electrically connected in parallel to each other. The first capacitor is electrically connected in parallel to the heating resistor portions. The switch section is electrically connected in series to the first capacitor. The first resistor is electrically connected in parallel to the first capacitor.