Fluid Ejection Device Data Signal Latch Circuitry
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Solution Overview
Problem
As the number of drop generators in inkjet printheads increases to improve printing speed and quality, the number of input pads required to energize firing resistors becomes impractical, leading to a need for a more efficient power distribution and control mechanism.
Innovation Solution
The implementation of a pre-charged firing cell circuit with a double data rate firing cell configuration, which allows for the energization of multiple firing resistors using fewer input pads by employing a clock latch circuit to latch data bits during each high voltage pulse, enabling efficient power distribution and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of drop generators in a printhead is increased to improve printing speed and quality, then printing quality and speed are improved, but the number of input pads required becomes impractical
Solution Approach 1:
Multiple firing resistors are connected in series between a single power lead and ground, merging multiple power delivery paths into one shared path. This allows multiple drop generators to share a common power input pad, reducing the total number of input pads required while maintaining the ability to independently control each firing resistor through its associated FET
Solution Approach 2:
A single input pad serves multiple functions by providing power to multiple firing resistors simultaneously. The power lead acts as a universal power distribution line that can energize any number of firing resistors in the primitive, making the input pad structure adaptable to varying numbers of drop generators without requiring additional pads
2Device complexity
If the number of drop generators per input pad is increased, then the number of input pads is reduced, but control of each firing resistor becomes more complex
Solution Approach 1:
The control function is segmented by introducing individual FETs for each firing resistor. Each FET acts as an independent switch that can be controlled separately, allowing precise control over each drop generator even though they share a common power lead. This segmentation of control authority simplifies the overall control architecture compared to alternative approaches
Solution Approach 2:
FETs serve as intermediary devices between the control signals and the firing resistors. The FETs translate control signals into appropriate current flow through the firing resistors, providing a standardized interface that simplifies control while enabling independent operation of each drop generator in the series-connected primitive
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 a higher number of drop generators per input pad, enhancing printing quality and speed while reducing the number of input pads required, thereby lowering costs and improving operational efficiency.
Implementation Method 1
The ink is heated with small electric heaters, such as thin film resistors referred to herein as firing resistors. Heating the ink causes the ink to vaporize and be ejected through the nozzles.
Implementation Method 2
Each firing resistor is coupled in series with the power lead and the drain-source path of a corresponding field effect transistor (FET). The gate of each FET in a primitive is coupled to a separately energizable address lead that is shared by multiple primitives.
Data Source
AI summary
A fluid ejection device includes a plurality of firing cells and a fire line adapted to conduct an energy signal including energy pulses. Each firing cell in the plurality of firing cells includes a firing resistor, a drive switch, a first data switch, and a second data switch. The drive switch is configured to enable the firing resistor to respond to the energy signal. The first data switch is configured to receive data signals that represent an image and to latch the data signals to provide latched data signals. The second data switch is configured to receive the latched data signals and control the drive switch to enable the firing resistor to respond to the energy signal and heat fluid to be ejected based on the latched data signals.