Printhead Temperature Correction Using Cascaded Diode Sensor Signals
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Solution Overview
Problem
Conventional inkjet printing apparatuses face challenges in maintaining consistent ink discharge due to variations in ink temperature, leading to printing quality deterioration, and the use of multiple diode sensors to address local temperature changes increases device cost and complexity.
Innovation Solution
A printing apparatus with a plurality of temperature detection elements arranged along the printhead, where a first correction unit corrects the signal from one temperature detection element, and a second correction unit further corrects the signal from another element based on the first correction, allowing for accurate head temperature calibration at a lower cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple Di sensors are provided on the head substrate to detect local temperature changes, then temperature detection accuracy is improved, but device cost and complexity increase due to required amplification circuits and calibration storage for each sensor
Solution Approach 1:
The patent merges the temperature detection function into a single Di sensor positioned at a representative location on the head substrate, eliminating the need for multiple sensors. The single sensor detects overall head temperature changes, and correction values are applied uniformly across all nozzles based on this centralized measurement, thereby reducing device complexity and cost while maintaining adequate temperature monitoring capability.
Solution Approach 2:
The single Di sensor serves as a universal temperature detection element for the entire head substrate, rather than having dedicated sensors for each nozzle or region. This universal sensor, combined with correction values stored in memory, provides temperature compensation for all nozzles, reducing the number of components while maintaining the ability to address temperature variations across the printing head.
2Measurement precision
If amplification circuits are added to each Di sensor to improve resolution, then temperature measurement precision is improved, but manufacturing variation increases causing voltage value variation before A/D conversion
Solution Approach 1:
The patent implements a feedback mechanism where correction values are determined based on the actual output characteristics of the amplification circuit and Di sensor. By measuring the real-world performance of these components and storing correction values that compensate for their specific variations, the system achieves consistent temperature measurements despite manufacturing tolerances in the amplification circuit and sensor.
3Measurement precision
If offset correction values are used to calibrate Di sensor and amplification circuit variations, then temperature detection accuracy is improved, but calibration complexity and cost increase
Solution Approach 1:
The system performs self-calibration by automatically determining correction values based on the actual output characteristics of its own Di sensor and amplification circuit. Rather than requiring external calibration equipment or complex manual adjustment procedures, the printing apparatus measures its own component variations and stores appropriate correction values in memory, thereby achieving accurate temperature detection while minimizing calibration complexity and cost.
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 method enables effective correction of head temperature across multiple detection elements at a lower cost, improving printing quality by maintaining consistent ink discharge and addressing local temperature variations without the need for extensive amplification circuits.
Implementation Method 1
use a diode sensor (to be referred to as a Di sensor hereinafter) that is formed on the same silicon substrate as that of a discharge heater. If the Di sensor is used, the temperature is detected using the fact that the output voltage of the Di sensor can be expressed as a linear function of an input temperature
Implementation Method 2
Since the output voltage of the Di sensor is weak, it is common practice to improve the resolution by amplifying the output voltage by the printing apparatus before A/D conversion
Implementation Method 3
there is known a thermal inkjet printing apparatus (to be referred to as a printing apparatus hereinafter) for discharging ink using a bubble generated by a heating element such as a heater
Data Source
AI summary
A printing apparatus includes a printhead with a plurality of print elements for generating energy used for printing an image on a print medium, a first temperature detection element and a second temperature detection element at positions different in a direction of a print element array in which the plurality of print elements are arrayed. The apparatus corrects a signal concerning a head temperature based on an output from the first temperature detection element, and corrects, based on the corrected signal concerning the head temperature, a signal concerning a head temperature output from the second temperature detection element.