Printhead Ink Level Sensor with Central Clearing Resistor
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Solution Overview
Problem
Inkjet printheads face performance degradation and erroneous ink-level detection due to decap-induced issues such as pigment-ink-vehicle separation and viscous plug formation during the decap period, which limits the sensitivity and effectiveness of printhead-integrated ink level sensors (PILS).
Innovation Solution
The implementation of a printhead-integrated ink level sensor system with a central clearing resistor and peripheral clearing resistors, along with a slot in the sense capacitor plate, enhances the clearing of the fluid sensing chamber, increasing decap time and sensitivity by uniformly heating and purging ink residue, thereby improving printer performance and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the printhead is left open and exposed to air during the decap period, then the printhead can be replaced or maintained, but performance degradation occurs due to pigment-ink-vehicle separation and viscous plug formation
Solution Approach 1:
The clearing resistors are activated before the decap period begins to prevent pigment-ink-vehicle separation and viscous plug formation. By applying heat to evaporate excess ink and maintain proper ink viscosity in advance, the system prevents performance degradation that would otherwise occur during the decap period, allowing longer idle times without reliability loss.
Solution Approach 2:
The system performs preliminary ink clearing and viscosity maintenance through the clearing resistors before the printhead enters the decap state. This preliminary action ensures that the ink remains in optimal condition during subsequent idle periods, extending the usable decap time while maintaining printing performance.
2Reliability
If peripheral clearing resistors are used to purge ink residue, then some clearing effect is achieved, but decap time and sensor sensitivity are insufficiently improved
Solution Approach 1:
The clearing system is segmented into two distinct components: peripheral clearing resistors positioned around the sensing chamber and a central clearing resistor positioned within the sensing chamber. This segmentation allows each resistor to perform a specific clearing function - the peripheral resistors handle outer ink residue while the central resistor addresses ink residue at the sensor location, improving overall clearing effectiveness without excessive complexity.
Solution Approach 2:
The clearing resistors are strategically positioned at different locations within the sensing chamber to address local ink residue problems. The central clearing resistor is placed directly in the sensing chamber to locally heat and clear ink residue that would otherwise interfere with sensor readings, thereby improving ink level detection accuracy without requiring a complete system redesign.
3Measurement precision
If the sensing chamber is not properly cleared of ink residue, then the structure remains simple, but sensor sensitivity decreases and erroneous detection occurs
Solution Approach 1:
The clearing resistors apply localized heating only to the sensing chamber and immediate surrounding areas where ink residue would most affect sensor performance. This partial action approach focuses energy consumption on the critical sensing region rather than heating the entire printhead, achieving improved measurement precision with moderate energy expenditure. The clearing is activated only when needed during decap periods, avoiding continuous energy consumption.
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
The system effectively extends decap time, enhances sensor sensitivity, and maintains accurate ink-level detection, leading to improved printer performance and reduced premature cartridge replacement.
Implementation Method 1
The plurality of clearing resistors is to clear the fluid sensing chamber of the fluid
Implementation Method 2
uniformly heating and purging ink residue
Implementation Method 3
The PILS comprises a sense capacitor whose capacitance varies based on the contents of a sensing chamber housing the sense capacitor
Data Source
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AI summary
The present subject matter relates to printhead-integrated ink level sensor (PILS) system. In an example implementation, the PILS system includes a sense capacitor plate in a fluid sensing chamber to sense a level of fluid in the fluid sensing chamber. The fluid sensing chamber is in fluid communication with a fluid reservoir of the printhead to receive fluid from the fluid reservoir. The sense capacitor plate includes at least one slot. The PILS system further includes at least one central clearing resistor and at least one peripheral clearing resistor to clear the fluid sensing chamber of the fluid. The central clearing resistor is provided in the at least one slot of the sense capacitor plate. The at least one peripheral resistor is provided in the fluid sensing chamber surrounding the sense capacitor plate.