Inkjet Printhead Heater Shutdown Control Using Voltage Drop Detection
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Solution Overview
Problem
Conventional inkjet printheads face issues with unwanted heater current flow during power shutdown due to the inability to control driving elements effectively, leading to unreliable print characteristics and increased heat generation.
Innovation Solution
An element substrate with high voltage logic circuits and level converters that receive a detection signal for logic voltage drop, inhibiting driving of printing elements to prevent unwanted current flow, even when logic circuit power is shut down.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a large-capacitance capacitor is provided to stabilize power supply, then power supply stability is improved, but power shutdown time increases
Solution Approach 1:
The invention applies preliminary action by detecting the logic voltage drop before it causes unwanted heater current flow. The detection circuit monitors the logic voltage and generates a detection signal that triggers the inhibition of driving elements in advance, preventing the harmful effect before it occurs.
Solution Approach 2:
The invention uses an intermediary detection circuit and detection signal as a mediator between the logic circuit power supply and the driving elements. This intermediary mechanism translates the logic voltage state into a controllable signal that directly controls the driving elements, enabling rapid response independent of capacitor discharge timing.
2Use of energy by moving object
If logic circuit power is shut down to save energy, then power consumption is reduced, but unwanted heater current flows due to inability to control driving elements
Solution Approach 1:
The detection circuit performs preliminary monitoring of the logic voltage and generates the detection signal before the power shutdown completes. This allows the high voltage logic circuits to inhibit the driving elements in advance, ensuring reliable control even when logic circuit power is completely shut down.
Solution Approach 2:
The system uses the logic voltage itself as the basis for generating the detection signal, creating a self-service mechanism where the power supply state automatically triggers the appropriate control action without requiring external intervention or complex control logic.
3Productivity
If the number of driven heaters per unit time increases to speed up printing, then printing speed is improved, but heat generation from level converters increases
Solution Approach 1:
The invention changes the operational parameters of the level converters by using high voltage logic circuits that can operate with lower power consumption. The detection signal mechanism allows for more efficient switching control, reducing the heat generation from level converters while maintaining high-speed printing capability.
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 ensures reliable inhibition of printing element driving during power shutdown, preventing unwanted current flow and improving the reliability and print characteristics of the printhead.
Implementation Method 1
A current is supplied to the printing elements to cause the heaters to generate heat. Ink droplets are discharged by film boiling of ink
Implementation Method 2
a plurality of first level converters provided in correspondence with the plurality of logic circuits and configured to boost a logic voltage having a second voltage lower than the first voltage of the selection signal
Data Source
AI summary
A recent inkjet printing apparatus includes a large-capacitance capacitor to stabilize a heater power supply. The presence of this capacitor requires a long time to drop the heater voltage at the time of power shutdown or the like. For this reason, an unwanted heater current may flow during the drop. To solve this problem, in this embodiment, a high voltage logic circuit is provided near a printing element, and a terminal is provided so that a signal can directly be input to this circuit. Heater driving control is performed via the terminal. This makes it possible to reliably control the heater regardless of the logic power supply state even if the logic voltage abruptly drops at the time of power shutdown or the like.