Pre-charge Line Routing Over Transistor Gate

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Solution Overview

Problem

The increasing number of nozzles in a printhead leads to a larger footprint for nozzle firing cells and a corresponding increase in the size of the printhead, limiting the ability to incorporate additional nozzles and affecting print quality.

Innovation Solution

Incorporating a nozzle firing cell design that includes a firing transistor and a pre-charge transistor with the pre-charge line routed over the gate of the pre-charge transistor, eliminating the need for jumpers and reducing the size of each nozzle firing cell from 112 µm to 75 µm, allowing for more compact and efficient integration of additional nozzles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the number of nozzles in the printhead is increased, then the print quality and efficiency are improved, but the footprint of the nozzle firing cells increases, leading to a larger printhead size

Engineering Contradiction:

Improveprint qualityVSAvoidprinthead size

Core Design Contradiction:

ProductivityVSArea of stationary object

Solution Approach 1:

The pre-charge line is routed over the gate of the pre-charge transistor in the vertical dimension, utilizing the third dimension (z-axis) to reduce the horizontal footprint of the firing cell circuitry on the printhead die

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The pre-charge line is nested over the gate region of the pre-charge transistor, effectively using the same spatial area for multiple circuit functions and reducing overall circuit footprint

Inventive Principle:

Principle #7Nested doll (Nesting)

2Reliability

If jumpers are used to route the pre-charge line, then the circuit can be completed, but energy losses occur and the circuit footprint increases

Engineering Contradiction:

Improvecircuit functionalityVSAvoidenergy loss

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The jumper component is extracted and eliminated from the circuit by routing the pre-charge line directly over the transistor gate, removing the source of energy loss while maintaining circuit functionality

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The transistor gate serves as an intermediary structure that the pre-charge line can route over, eliminating the need for separate jumper connections and reducing energy loss in the pre-charge path

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentEP3174718B1Pre-charge line routed over pre-charge transistor

Publication Date: 2019.03.06 HEWLETT PACKARD DEVELOPMENT COMPANY LP

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AI summary

A nozzle firing cell may comprise a firing transistor and a pre-charge transistor having a source and drain coupled between a pre-charge iine and a gate of the firing transistor wherein the pre-charge iine is routed over the gate of the pre-charge transistor. A fluid ejection device may comprise a circuit comprising a nozzie firing ceil, the nozzle firing cell comprising a firing transistor and a pre-charge transistor having a source and drain coupled between a pre- charge Sine and a gate of the firing transistor in which the pre-charge line is routed over the gate of the pre-charge transistor. A circuit may comprise a number of firing transistors and a number of pre-charge transistors each having a source and drain coup!ed between a pre-charge line and a gate of one of the firing transistors in which the pre-charge line is routed over each of the gates of the pre-charge transistors.