Switch Circuit Thermal Management in Liquid Ejecting Heads
Solution Overview
Problem
In liquid ejecting heads, especially those with high-density nozzles, the switch circuit tends to overheat due to increased temperature from high current density, impedance, and reduced heat dissipation, leading to unstable operation.
Innovation Solution
The switch circuit is positioned between two flow channels in a liquid ejecting head, allowing heat to dissipate through the liquid within these channels, and the circuit substrate is placed between the reserve chamber and pressure chamber to facilitate efficient heat dissipation, reducing the likelihood of the switch circuit overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the switch circuit is highly integrated to support high-density nozzles, then the nozzle density and image resolution are improved, but the switch circuit temperature increases and operation stability deteriorates
Solution Approach 1:
The patent introduces liquid flow channels as an intermediary heat dissipation medium between the switch circuit and the external environment. The liquid circulating through the flow channels directly contacts the circuit substrate, serving as a thermal intermediary that transfers heat away from the switch circuit effectively, thereby maintaining operational stability despite high integration density.
Solution Approach 2:
The patent utilizes hydraulic cooling by circulating liquid through flow channels that are in thermal contact with the circuit substrate. This hydraulic system removes heat from the switch circuit by convection as the liquid flows through the channels, enabling the circuit to operate stably at high densities without overheating.
2Volume of moving object
If the switch circuit is miniaturized for high integration, then the device size is reduced, but the impedance increases and heat dissipation performance deteriorates
Solution Approach 1:
The patent embeds the flow channels within or in direct thermal contact with the circuit substrate structure. The cooling channels are nested into the substrate itself, allowing the miniaturized switch circuit to be integrated with the cooling system in a compact arrangement. This nested configuration enables effective heat dissipation from the small-scale circuit without increasing the overall device volume significantly.
Solution Approach 2:
The patent changes the thermal management parameters by introducing active liquid cooling through the flow channels. This parameter change (from passive to active cooling) compensates for the reduced heat dissipation capacity caused by miniaturization, allowing the small switch circuit to maintain low operating temperature despite high current density and impedance.
3Area of stationary object
If the switch circuit is exposed to air for heat dissipation, then the heat dissipation area is increased, but the circuit is vulnerable to external noise and the overall heat dissipation efficiency is reduced
Solution Approach 1:
The patent uses liquid as an intermediary medium for heat dissipation instead of direct air exposure. The liquid flow channels provide a controlled thermal interface that dissipates heat through convection while keeping the circuit substrate enclosed. This intermediary approach maintains effective heat transfer area while protecting the circuit from external electromagnetic noise and other environmental harmful factors.
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 configuration effectively dissipates heat generated by the switch circuit, maintaining stable operation even at high densities of nozzles and high ejection frequencies, while also enabling miniaturization and increased reservoir capacity.
Implementation Method 1
The heat generated at the switch circuit can be therefore dissipated through the liquid within the first flow channel and the second flow channel
Implementation Method 2
the liquid circulates from the first end of the first flow channel through the second end of the first flow channel, the second end of the second flow channel, and the first end of the second flow channel
Data Source
AI summary
A liquid ejecting head includes: a piezoelectric element driven with a drive signal; a switch circuit which is provided on a circuit substrate; a pressure chamber which is filled with liquid and changes pressure inside in accordance with the drive by the piezoelectric element; and a reserve chamber which reserves the liquid to be supplied to the pressure chamber. The piezoelectric element is provided in a sealed space defined by a plurality of members including the circuit substrate. The reserve chamber includes a first flow channel and a second flow channel. A first end of the first flow channel communicates with a first end of the second flow channel. A second end of the first flow channel communicates with a second end of the second flow channel. The circuit substrate and switch circuit are provided between the first flow channel and the second flow channel.