Head Unit Heat Sink with Conductive Gel for Driving Circuit Thermal Management
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Solution Overview
Problem
The increasing number of nozzles in liquid discharge apparatuses for high-definition image formation leads to higher current output and heat generation in driving signal output circuits, causing component aging, affecting ink properties, and reducing reliability, with existing heat dissipation technologies being insufficient for efficient heat release.
Innovation Solution
A head unit with a substrate, driving circuit, and heat sink, utilizing heat conductive elastic bodies for improved heat dissipation, including a gel-based heat conductive elastic body with flame retardancy and electric insulation properties, positioned between the heat sink and driving circuit components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of nozzles is increased to achieve higher definition, then the image quality is improved, but the current output and heat generation in the driving signal output circuit increase
Solution Approach 1:
The patent divides the driving signal output circuit into multiple independent amplifier circuits, each responsible for driving a specific group of nozzles. This segmentation allows heat to be distributed across multiple smaller heat generation zones rather than concentrated in a single circuit, thereby managing heat generation more effectively while supporting a larger total number of nozzles for high-definition imaging.
Solution Approach 2:
The patent introduces a third dimension for heat dissipation by stacking the amplifier circuits vertically on the substrate and providing heat sinks on both the upper and lower sides of the substrate. This three-dimensional heat dissipation architecture allows heat to be released in multiple directions (upward and downward), significantly improving heat management capability while accommodating increased nozzle count for higher definition.
2Measurement precision
If the operating frequency of the driving signal output circuit is increased to improve driving accuracy, then the waveform accuracy is improved, but the current output and heat generation further increase
Solution Approach 1:
By segmenting the high-frequency driving signal generation into multiple parallel amplifier circuits, each circuit operates at high frequency for its assigned nozzles but with reduced individual current load. This segmentation allows high operating frequency for waveform accuracy while distributing the thermal burden across multiple circuits, preventing excessive heat generation in any single location.
Solution Approach 2:
The patent provides localized heat dissipation structures (heat sinks) positioned directly adjacent to each amplifier circuit on the substrate. This local quality approach ensures that heat generated by high-frequency operation in each specific amplifier circuit is immediately dissipated at its source, allowing high operating frequencies for waveform accuracy without accumulating excessive heat that would limit performance.
3Measurement precision
If the number of nozzles is increased to respond to high definition demand, then the image quality is improved, but the region available for heat dissipation becomes insufficient due to miniaturization
Solution Approach 1:
The patent transitions from two-dimensional heat dissipation (single-sided heat sinks on the substrate) to three-dimensional heat dissipation by placing heat sinks on both the upper and lower sides of the substrate. This dimensional change effectively doubles the heat dissipation surface area available, providing sufficient heat release capability even as the apparatus is miniaturized and the planar area for heat dissipation is reduced.
Solution Approach 2:
The substrate serves multiple functions: it provides mechanical support for the nozzles and driving circuits, and simultaneously acts as a heat transfer medium that conducts heat from the amplifier circuits to the heat sinks on both its upper and lower surfaces. This multi-functionality allows the same structural element to contribute to both the high-definition nozzle array and adequate heat dissipation, resolving the conflict between miniaturization and heat dissipation area.
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
Enhances heat dissipation efficiency, reducing component aging and improving reliability by effectively managing heat generated in the driving signal output circuits, thereby maintaining ink discharge quality and apparatus performance.
Implementation Method 1
a first heat conductive elastic body among the plurality of heat conductive elastic bodies is positioned between the heat sink and the first integrated circuit, and is in contact with the heat sink and the first integrated circuit, a second heat conductive elastic body among the plurality of heat conductive elastic bodies is positioned between the heat sink and the first transistor, and is in contact with the heat sink and the first transistor
Implementation Method 2
the first heat conductive elastic body and the second heat conductive elastic body are in a form of a gel having flame retardancy and electric insulation property
Data Source
AI summary
There is provided a head unit including: a substrate on which a first driving circuit is disposed; a heat sink fixed to the substrate; and heat conductive elastic bodies positioned between the substrate and the heat sink, in which the first driving circuit includes a first integrated circuit, a first amplifier circuit including a first transistor, and a first smoothing circuit that outputs the first driving signal, in which a first heat conductive elastic body is in contact with the heat sink and the first integrated circuit, a second heat conductive elastic body is in contact with the heat sink and the first transistor, and the first heat conductive elastic body and the second heat conductive elastic body are in a form of a gel having flame retardancy and electric insulation property.