Printhead Nozzle Discharge Detection Using Constant Current Sensing
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Solution Overview
Problem
Conventional inkjet printing methods using printheads with thermal energy struggle to accurately determine the discharge status of nozzles due to noise interference in temperature signal corrections, leading to inaccurate ink droplet discharge and reduced precision.
Innovation Solution
An element substrate with a heater, temperature sensor, and determination circuit that uses a constant electric current and threshold voltage to accurately determine the ink discharge status, minimizing noise and improving precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature signal correction is performed by multiplying by a gain, then temperature information is obtained, but noise increases together with the useful signal, reducing determination accuracy
Solution Approach 1:
The patent extracts only the necessary temperature information at the specific timing when the ink droplet contacts the heater, rather than processing the entire temperature signal curve. The determination circuit extracts the temperature value at the precise moment of droplet impact, separating the useful information from the noisy portions of the signal that occur at other timings.
Solution Approach 2:
The patent performs preliminary identification of the temperature signal characteristics before final determination. The system预先 identifies the timing pattern when temperature changes occur due to ink droplet contact, and uses this timing information to selectively extract the relevant temperature value, avoiding subsequent noise amplification issues.
2Reliability
If discharge status is determined based on temporal change in temperature information, then discharge detection is performed, but it is impossible to correct variations in timing and tail droplet effects
Solution Approach 1:
The patent performs preliminary identification of the temperature signal characteristics before final determination. The system预先 identifies the timing pattern when temperature changes occur due to ink droplet contact, and uses this timing information to selectively extract the relevant temperature value, avoiding subsequent noise amplification issues.
Solution Approach 2:
The patent employs periodic sampling of the temperature signal at specifically determined time intervals relative to the heater drive pulse. By sampling at predetermined periodic intervals synchronized with the expected droplet contact timing, the system consistently captures the relevant temperature information while avoiding timing variations and tail droplet interference.
3Measurement precision
If conventional temperature signal processing is used, then temperature information is obtained, but it is impossible to determine discharge status with high accuracy for deteriorated nozzles
Solution Approach 1:
The patent replaces complex signal processing operations with a simpler timing-based extraction method. Instead of using gain multiplication and temporal change analysis that amplify noise and timing errors, the system substitutes these with direct sampling of the temperature signal at pre-identified optimal timing points, providing more reliable measurements even when nozzle performance degrades.
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 solution enables high-accuracy determination of nozzle discharge status, even for deteriorated nozzles, by isolating the electric current and threshold voltage, thus enhancing the overall precision and reliability of inkjet printing.
Implementation Method 1
a heater configured to heat ink and discharge ink from a nozzle
Implementation Method 2
a temperature sensor provided in correspondence with the heater
Data Source
AI summary
An element substrate provided in a printhead includes a heater configured to heat ink and discharge the ink from a nozzle, a temperature sensor provided in correspondence with the heater, an electric current source configured to energize the temperature sensor with an electric current based on an electric current value specified by an externally input first signal, and a determination circuit configured to determine an ink discharge status of the nozzle based on a voltage output from the temperature sensor energized with the electric current and a threshold voltage specified by an externally input second signal, and output a determination result signal.