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High-Voltage Piezoelectric Drivers for Inkjet Print Heads  

Regardless of the type of print head design and application space, Microchip can help get your product to market efficiently. Microchip’s high-voltage driver solutions for piezoelectric ink chambers create highly reliable systems based on proven wafer technology. Our expertise in high-voltage product design enables us to provide superior engineering support, significantly reducing your design risk. Find the solution that fits your needs in this flexible portfolio which supports print head designs for printing applications in industrial, 3D, textile, ceramic and more.

Piezoelectric Print Head Actuation

As shown in the diagrams below, the ink chamber is surrounded by a piezoelectric material, which injects and ejects ink when expanded or contracted. High-voltage (HV) drivers are needed to generate a series of high-voltage pulses, activating the piezoelectric medium to drive the ink in and out of the chamber. The piezoelectric element expands and shrinks based on the voltage polarity across the material. The ink volume can be precisely controlled based on the voltage applied; precise high-voltage drivers allow for precise ink control.

  • Apply high voltage (from 50 to 200V) across a piezoelectric element to create mechanical movement
  • Modulate the actuation pulse duration, voltage level and polarity to control drop mass and speed
  • Slew rate requirement for different print head design varies from 40 to 120 V/ms
  • What can you control?
    • Slew rate: Controls the ink droplet velocity
    • Pulse amplitude: Controls the ink droplet mass
    • Pulse width: Controls the repetition rate

Proven Solutions to Meet Design Requirements

  • High current capability
  • High slew rate
  • Low on resistance
  • Low drift
  • Low temperature coefficient
  • Tradeoff between voltage, current, slew rate, power consumption and channel density

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Print Head Actuation Diagram
Inkjet Printer Types Explained
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Continuous Ink

Ink droplets are generated continuously and accelerated toward a printing target. On their way, these ink droplets pass by high-voltage electrodes controlled by fast switching HV drivers. During this process some droplets are electrostatically charged, while others are not.

Next, they pass by a high-voltage deflection plate. The uncharged droplets are allowed to reach the target, while the charged ones are deflected into an ink gutter for recycling.

Drop-on-Demand (DoD)

High-voltage pulses applied to a piezo ink chamber alter the state of the chamber in order to interchangeably suck in, form and push out a droplet of ink and then propel it in direction of target (paper, fabric, etc.).

In order to match the resonance characteristics of the ink chamber, the HV driver generates a series of high-voltage pulses of a particular height, duration and shape.

How does Piezoelectric Material Work?
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Physical dimension changes by applying electric field across piezoelectric material. The following illustration demonstrates the state of the piezoelectric material in each voltage condition. The material expands with an increase in voltage and shrinks when the voltage is lowered. 

How Does It Work
Common Applications
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  • Paper printing
  • Textile printing
  • Ceramic tile printing
  • OLED panel printing
  • 3D printing
  • Biomedical printing
Piezoelectric Load Characteristics
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  • The piezoelectric element behaves like a capacitive load
Load Characteristic Diagram 1
  • Capacitance varies from a few tens of picofarad to a few nano-farad
  • Series resistance varies from a few tens of ohms to a few hundreds of ohms
  • Slew rate: dVc / dt = I / C
Load Characteristic Diagram 2
Piezoelectric Driver Circuit Topologies
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  • Open drain output
    • Up to 300V
  • Unipolar push-pull output
    • Up to 300V
  • Bipolar push-pull output
    • Up to 200V
  • Operational amplifier
    • Up to 300V up to 1000 V/ms