Inkjet Print Head Temperature Control via Weighted Average
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Inkjet printing apparatuses with full line type print heads face challenges in accurately detecting and controlling temperature distributions, leading to density unevenness in images due to temperature gradients and the inclusion of non-printing regions in temperature calculations.
Innovation Solution
An inkjet printing apparatus with a print head featuring a substrate with multiple print elements and temperature sensors, utilizing a determining unit to calculate a weighted average representative temperature by lining up detection temperatures and applying drive pulses based on this calculated temperature for stable ink ejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a plurality of temperature sensors are arranged on a single chip to detect temperature distribution, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The print head is divided into multiple chip units, each containing multiple temperature sensors arranged in a matrix pattern. This segmentation allows independent temperature detection for each chip region, improving measurement precision while managing device complexity through modular architecture
Solution Approach 2:
Temperature sensors are specifically arranged to detect temperatures at different locations within each chip (e.g., center and corner positions). This local quality approach ensures accurate temperature distribution detection across the print head surface, enabling precise compensation for thermal variations
2Device complexity
If representative temperature is calculated using all detection temperatures including non-printing regions, then device complexity is reduced, but manufacturing precision deteriorates
Solution Approach 1:
The patent extracts and identifies printing region information from image data, then uses this information to selectively include or exclude specific temperature sensor readings when calculating the representative temperature. This extraction approach ensures that only temperatures from active printing regions contribute to the calculation, improving image density uniformity
Solution Approach 2:
The set of temperature sensors used for representative temperature calculation is made dynamic based on the printing region. Different printing patterns (e.g., full-page vs. partial-page) result in different subsets of temperature readings being included, allowing the system to adapt to various printing scenarios and maintain precision
3Reliability
If PWM control is applied to adjust pulse width based on chip temperature, then reliability of ejection amount control is improved, but device complexity increases
Solution Approach 1:
The system implements feedback control by continuously monitoring temperatures from multiple sensors, calculating the representative temperature, and adjusting the PWM pulse width accordingly. This closed-loop feedback mechanism compensates for thermal variations in real-time, ensuring reliable and stable ink ejection amounts despite temperature changes
Solution Approach 2:
The patent changes the PWM control parameter (pulse width) based on the detected representative temperature. By dynamically adjusting this parameter in response to temperature measurements, the system maintains consistent ejection performance across varying thermal conditions without requiring complex hardware modifications
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 approach ensures stable image output without density unevenness by accurately controlling the drive pulses based on a representative temperature, effectively addressing temperature distribution challenges in full line type inkjet printing.
Implementation Method 1
a plurality of temperature sensors arranged on the chip to detect temperatures in a comprehensive manner
Implementation Method 2
an electrothermal conversion element provided in the ink passage to heat the ink
Implementation Method 3
thermal energy is provided to a plurality of print elements arranged in the print head according to image data to eject ink
Data Source
AI summary
There is provided an inkjet printing apparatus which can output a stable image without density unevenness by performing appropriate drive control to print elements based upon an appropriate representative temperature of a chip whatever image data is printed on a print medium. For this purpose, detection temperatures of a plurality of temperature sensors are lined up in high temperature order, and coefficients by which the respective detection temperatures are multiplied, are determined to be associated with that order at the lining-up, determining a representative temperature by the weighted average method. The common drive pulse associated with to the individual chip based upon the representative temperature thus obtained, to be applied thereto. Thereby even if temperature variations of print elements on the chip exist, it is possible to appropriately control the entire chip in temperature.