Liquid Ejecting Head Dual Temperature Sensor Drive Circuit Control
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Solution Overview
Problem
In circulation-type liquid ejecting devices, it is challenging to accurately control the temperature of the drive circuit due to a temperature difference between the actuator and the drive circuit, making it difficult to determine the appropriate temperature for controlling the liquid ejecting device solely by measuring the liquid temperature.
Innovation Solution
The implementation of a dual-temperature sensor system, where a first thermistor measures the temperature near the drive circuit and a second thermistor measures the liquid temperature in the circulation path, allowing for independent temperature control of the drive circuit and liquid, with the processor using AD conversion to determine accurate resistance values and temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single temperature sensor is used to measure liquid temperature for control, then the control system is simple, but the temperature control precision is insufficient due to temperature difference between actuator and drive circuit
Solution Approach 1:
The temperature measurement function is segmented into two independent measurement points: one for the actuator temperature and one for the drive circuit temperature. This allows each sensor to independently monitor its specific location, resolving the contradiction by improving measurement precision through spatial segmentation while keeping the overall system complexity manageable through functional separation.
Solution Approach 2:
Different temperature measurement qualities are applied to different locations: the actuator temperature is measured with a sensor positioned at the actuator, while the drive circuit temperature is measured with a separate sensor at the circuit location. This local quality approach ensures each critical component has accurate temperature data specific to its operating conditions, improving overall control precision without requiring a single complex omnibus sensor system.
2Reliability
If the drive circuit temperature is not independently monitored, then the device structure is simple, but overheating protection and temperature control reliability are insufficient
Solution Approach 1:
The temperature monitoring system is segmented into independent actuator monitoring and drive circuit monitoring subsystems. Each subsystem has its own dedicated sensor and control logic, ensuring that the drive circuit temperature is independently monitored with the same reliability as the actuator temperature, thereby improving overall system reliability while maintaining structural simplicity through modular design.
Solution Approach 2:
The drive circuit temperature sensor acts as an intermediary between the drive circuit and the control system, providing independent temperature data that enables the controller to make informed decisions about drive circuit operation. This intermediary measurement capability enhances reliability by preventing overheating without requiring direct thermal contact or complex integrated sensing within the circuit board itself.
3Manufacturing precision
If temperature compensation is not applied to drive circuit variations, then the control algorithm is simple, but the liquid ejection precision deteriorates due to drive circuit temperature changes
Solution Approach 1:
A feedback loop is established using the drive circuit temperature sensor to continuously monitor drive circuit temperature and automatically adjust control parameters. The controller uses the measured drive circuit temperature to compensate for temperature-induced variations in drive circuit characteristics, thereby maintaining precise liquid ejection control despite temperature changes. This feedback mechanism improves ejection precision while adding only moderate complexity through standard temperature compensation algorithms.
Solution Approach 2:
The control system dynamically changes operational parameters based on drive circuit temperature measurements. When the drive circuit temperature varies, the controller adjusts compensation parameters such as drive voltage or pulse width to maintain consistent liquid ejection performance. This parameter adaptation approach improves manufacturing precision by compensating for thermal drift without requiring complex hardware modifications.
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 precise temperature management of both the drive circuit and the liquid, preventing overheating and ensuring stable viscosity for efficient liquid ejection, while also detecting connector fitting abnormalities and preventing power-on issues due to misalignment.
Implementation Method 1
a first temperature sensor (27) provided on a circuit board (26) on which the drive circuit (26a) is mounted, the first temperature sensor (27) measuring a temperature near the drive circuit (26a)
Implementation Method 2
a second temperature sensor (28) measuring a temperature of the liquid in the circulation path (15)
Implementation Method 3
with the processor using AD conversion to determine accurate resistance values and temperatures
Data Source
AI summary
A liquid ejecting head includes an actuator communicating with a nozzle, configured to eject liquid from the nozzle, a drive circuit on a circuit board configured to drive the actuator, a flow path of liquid circulating, a first temperature sensor configured to measure a temperature on a surface on the circuit board proximate to the drive circuit, and a second temperature sensor configured to measure a temperature of a liquid on the flow path of liquid circulating.