Element Substrate Multi-Finger Transistor Layout for Printhead
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Solution Overview
Problem
Conventional liquid discharge heads face issues with increased viscosity of ink near orifices due to volatile component evaporation, leading to discharge failures and inefficient component layout, which results in higher manufacturing costs.
Innovation Solution
The implementation of an element substrate with alternating arrays of discharge and pump heaters, driven by transistors with multi-finger configurations of equal gate widths but differing finger counts, to efficiently manage ink circulation and reduce substrate size and manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large-area discharge heater is arranged to ensure ink discharge performance, then ink discharge performance is improved, but the heater current becomes larger and the semiconductor chip area increases
Solution Approach 1:
The heater array is segmented into two distinct types: discharge heaters for ink ejection and pump heaters for ink circulation. Each type is independently controlled by separate driver transistors with optimized finger counts, allowing the chip area to be efficiently utilized without requiring excessive area for any single heater type.
Solution Approach 2:
Different regions of the heater array are assigned different functions with locally optimized characteristics. Discharge heaters use a first number of transistor fingers optimized for high current density, while pump heaters use a second number of transistor fingers optimized for lower current density, allowing each region to operate at optimal efficiency without compromising overall chip area.
2Productivity
If a sufficient pumping capability is ensured by arranging a large-area pump heater, then pumping capability is improved, but the heater current becomes larger and the semiconductor chip area increases
Solution Approach 1:
The heater array is segmented into two distinct types: discharge heaters for ink ejection and pump heaters for ink circulation. Each type is independently controlled by separate driver transistors with optimized finger counts, allowing the chip area to be efficiently utilized without requiring excessive area for any single heater type.
Solution Approach 2:
Different regions of the heater array are assigned different functions with locally optimized characteristics. Discharge heaters use a first number of transistor fingers optimized for high current density, while pump heaters use a second number of transistor fingers optimized for lower current density, allowing each region to operate at optimal efficiency without compromising overall chip area.
3Ease of manufacture
If drivers for heaters with different current values are designed to be identical in size, then manufacturing is simplified, but the semiconductor chip area increases due to matching the larger driver size
Solution Approach 1:
The driver circuit is segmented into two types of transistors: first driver transistors for discharge heaters and second driver transistors for pump heaters. Each transistor type has a different number of fingers optimized for its specific current requirements, allowing area-efficient design while maintaining manufacturing feasibility through standardized fabrication processes.
Solution Approach 2:
The transistor finger count parameter is changed between driver types to optimize current handling capabilities. First driver transistors have a first number of fingers for high current discharge operation, while second driver transistors have a second number of fingers for lower current pump operation, allowing area optimization without sacrificing manufacturing ease.
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 improves component layout efficiency and reduces manufacturing costs by optimizing the sizes of driver transistors for heaters with different current requirements, ensuring effective ink circulation and discharge performance.
Implementation Method 1
a plurality of first heaters arrayed in a predetermined direction, a plurality of second heaters arranged alternatingly with the plurality of first heaters
Implementation Method 2
a plurality of first driver transistors configured to drive the plurality of first heaters, and a plurality of second driver transistors configured to drive the plurality of second heaters
Implementation Method 3
the viscosity of the liquid in the vicinity of each orifice, from which the liquid is discharged, increases as a volatile component contained in the liquid evaporates from the orifice
Data Source
AI summary
According to an embodiment of the present disclosure, to improve a layout efficiency of an element substrate to be integrated in a printhead and reduce a production cost of the element substrate, a driving method and a size of a first driver transistor used for driving a first heater for ink circulation and a driving method and a size of a second driver transistor used for driving a second heater for discharging ink to print are optimized, respectively. More specifically, the first driver transistor and the second driver transistor have multi-finger configurations, gate widths of the multi-finger configurations are equal to each other, and the number of fingers forming each first driver transistor is different from the number of fingers forming each second driver transistor.