Printhead Temperature Regulation via Localized Warming Pulses
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Solution Overview
Problem
Inkjet printheads often experience uneven temperature distribution due to the use of a single thermal sense resistor, leading to thermal gradients that can result in suboptimal print quality, as temperatures can rise above or fall below the desired range, especially during heavy printing or in areas with varying inkjet density and circuitry.
Innovation Solution
A temperature regulating circuitry unit comprising an analog memory, temperature sensor, comparator, and pulse circuit is used to measure and compare thermal voltages across local areas of the printhead, selectively transmitting warming pulses to maintain uniform temperature across the printhead, thereby reducing thermal gradients and ensuring high print quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single thermal sense resistor is used to regulate printhead temperature, then device complexity is reduced and manufacturing cost is lowered, but temperature uniformity across the printhead deteriorates, causing thermal gradients and suboptimal print quality
Solution Approach 1:
The printhead is divided into multiple local areas, each with its own temperature sensor and warming pulse control. This segmentation allows independent temperature regulation of different regions, eliminating thermal gradients while avoiding the complexity of a fully distributed control system.
Solution Approach 2:
Different regions of the printhead receive customized warming pulses based on their specific temperature needs. The system applies local quality control by tailoring the heating response to each local area's requirements, ensuring uniform temperature distribution without requiring complex global control.
2Ease of manufacture
If thermal sense resistors are used for temperature regulation, then the system is simple to implement, but measurement precision deteriorates due to averaging temperature across the entire printhead, causing temperatures to rise above or fall below the desired range
Solution Approach 1:
The temperature measurement function is segmented across multiple local sensors rather than using a single averaged measurement. This allows precise local temperature detection while keeping the overall system simple and easy to manufacture.
Solution Approach 2:
Each local area serves itself by having its own temperature sensor and control circuitry that independently regulates its temperature. This self-service approach eliminates the need for complex centralized control while improving measurement precision.
3Device complexity
If warming pulses are applied uniformly across the printhead, then temperature regulation is simplified, but energy efficiency deteriorates by heating areas that do not require it, increasing power consumption
Solution Approach 1:
Warming pulses are applied with local quality control, where each region receives heating only when its specific temperature requirements demand it. This eliminates wasted energy on already-warm areas while keeping the control mechanism relatively simple.
Solution Approach 2:
The warming pulse application is made dynamic and adaptive, adjusting the heating response based on real-time temperature feedback from each local sensor. This dynamic control optimizes energy usage without requiring overly complex static control mechanisms.
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 solution effectively regulates temperature uniformly across the printhead, reducing thermal gradients and maintaining high print quality by only heating areas that require it, thus minimizing visible print defects.
Implementation Method 1
The temperature sensor measures a thermal voltage of at least one of the plurality of local areas of the printhead
Implementation Method 2
The pulse circuit selectively transmits a series of warming pulses to the at least one of the plurality of local areas of the printhead
Data Source
AI summary
In some examples, a method of regulating a temperature of a printhead includes charging, in a first state of a temperature regulator, an analog memory to a reference voltage that corresponds to a predetermined temperature of the printhead. The temperature regulator monitors, during a second state, the temperature of the printhead, the monitoring including measuring a thermal voltage representing an actual temperature of at least a first local area of a plurality of local areas of the printhead, and comparing, with a comparator, the reference voltage to the thermal voltage to obtain a comparison result for at least the first local area. Based on the comparison result, a series of warming pulses from a warming pulse circuit to at least the first local area is selectively enabled.