Print Head Jet Stack Heating and Temperature Sensing
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Solution Overview
Problem
Conventional thermistors in print heads experience high failure rates, design and space constraints, and maintenance issues, making them unsuitable for temperature measurement in high jet density print heads with flexible circuit technology.
Innovation Solution
A flexible circuit integrated with a copper layer as both a heat source and temperature sensing element, eliminating the need for separate thermistors by using resistive heating and temperature sensing capabilities within the same layer, connected in series with a voltage source and a transistor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional thermistors are used for temperature measurement in print heads, then temperature monitoring is achieved, but the failure rate increases and maintenance requirements increase
Solution Approach 1:
The patent combines the temperature sensing function with the flexible circuit board by using a temperature sensing trace integrated directly into the circuit layer. This eliminates the need for separate thermistor components and their associated attachment processes, thereby reducing failure points and maintenance requirements while maintaining temperature monitoring capability.
2Reliability
If conventional thermistors are used for temperature measurement, then temperature monitoring is provided, but space constraints are not met in high jet density designs
Solution Approach 1:
The temperature sensing trace is integrated into the flexible circuit board structure itself, sharing the same space with other circuit elements. This eliminates the need for additional dedicated space that separate thermistors would require, making the design suitable for high jet density print heads where space is limited.
3Reliability
If separate thermistor components are attached during manufacturing, then temperature sensing is achieved, but manufacturing complexity increases
Solution Approach 1:
The temperature sensing trace is formed as an integral part of the flexible circuit board manufacturing process, using the same lamination and trace formation techniques as other circuit elements. This eliminates separate attachment steps for thermistors, simplifying the manufacturing process and reducing assembly complexity.
4Reliability
If conventional thermistor designs are used, then temperature measurement is provided, but material requirements and costs increase
Solution Approach 1:
The temperature sensing trace uses the same flexible circuit board materials (copper traces on flexible substrate) as the rest of the circuit, eliminating the need for separate thermistor materials. This reduces overall material requirements and leverages existing material investments in the flexible circuit board structure.
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 reduces material requirements, simplifies manufacturing, enhances reliability, and lowers costs by integrating heat spreading and temperature sensing functions within a single layer, providing effective temperature monitoring without the need for conventional thermistors.
Implementation Method 1
a first copper layer having heat spreading characteristics through the first layer and including a resistive heat source the restive heat source electrically connected in series to a voltage source and a switch
Implementation Method 2
a first copper layer having heat spreading characteristics through the first layer
Implementation Method 3
a second copper layer on a side of the electrically insulative layer opposite the first copper layer, the second copper layer having a temperature sensing element to sense a temperature of the print head without a thermistor
Data Source
AI summary
A print head has a jet stack, a jet stack heating and temperature measuring element thermally connected to the jet stack, the jet stack heating and temperature measuring element including: a first, etched copper layer having heat spreading characteristics and including a resistive heat source electrically connected in series to a voltage source and a switch; an electrically insulative on a back side of the first copper layer; and a second, etched copper layer on a side of the electrically insulative layer opposite the first copper layer, the second copper layer having a temperature sensing element to sense a temperature of the print head without a thermistor, the temperature sensing element connected in series with a voltage source and a transistor. A print head may use a thermistor but the heat spreading layer eliminates the need for a heat sink to attach to the print head.