Tech Tips

Piezo drivers are amplifier type power supplies for the stable driving of the amount of displacement and the amount of vibration for each piezo element based on its purpose. Piezo elements have the characteristics of capacitive elements. They require an amplifier type power supply that can both discharge and retain the output power supply, rather than a normal programmable DC power supply, in order to provide optimal drive. In addition, when driven at a fast response speed, not only responsiveness but also more output current is required. The first step in choosing a piezo driver is to choose a power supply that matches both the element that is used and the usage conditions (waveform, frequency, load). With pulse driving with an actuator, ringing tends to occur in the output waveform, and in some cases abnormal oscillation may occur. Degradation and breakage of the piezo element occurs in such cases. Our designs have taken this point into consideration. The Matsusada Precision piezo driver is a versatile product that supports a variety of piezo elements (and can be applied to piezo elements with a wide range of capacities), and provides stable operation. Please try this power supply to optimally drive and achieve the full performance of piezo elements.

Piezo drivers

Examples Applied Piezo

X-Y stage and lens/mirror positioning, fusion bond positioning for optical fiber, inkjet printer and valve/electronic valve control, vibration of part feeder, generation of ultrasonic waves, precise positioning of analyzers, etc.

Driving microscope lenses and stages

The figure on the left is a simplified representation of using a piezo driver to focus and operate the lens of a microscope and to position the sample stage. A 3-channel output model allows positioning along the X, Y, and Z axes to be performed with a single unit.

This image shows structures to drive a microstage with a piezo element using a piezo driver.

Positioning for detailed machining

The figure on the left is a simplified representation of using a piezo driver for the machining of metal.

Positioning for detailed machining

Fine adjustment of optical measuring devices

The figure on the left shows a Michelson interferometer, which measures the accuracy of the surfaces of light source lenses and mirrors.

Each time the sample changes, images A and B are re-aligned in units of μm.
A piezo actuator is used to make fine adjustments to this mirror.

Fine adjustment of optical measuring devices

Relationship Between Response Speed and Output Current

When choosing a piezo driver, the:

  • Capacitance of the piezo element
  • Driving voltage for the required amount of displacement
  • Waveform for driving the piezo element

determine the output current of the driver.
Check the individual specifications for each piezo driver to choose a model that satisfies these performance conditions.

The following formula is used to find the output current.
For sine wave drive: Imean ≒ 2.2fC VP-P

To find the operating frequency at which each driver can be driven,
the formula above is changed to f = Imean/2.2C VP-P
For pulse drive: IP = VP-PC/Tr

(While the peak current IP is increased, the duration available for output is limited to 10 ms or less. Refer to the response speed in the specifications for each driver.)
To find the rise time for each driver, the formula above is changed to Tr = VP-PC/IP. (The same applies to Tf.)
However, since it is limited by the value of the output resistance, set the rise time to either the above formula or 3τ = 3RC, whichever is slowest.

  • Imean: Rated output current ... (A)
  • IP: Peak output current ... (A)
  • VP-P: Output voltage width P-P value ... (V)
  • R: Output resistance ... (Ω)
  • C: Piezoelectric capacitance ... (F)
  • Tr: Rise time ... (S)
  • Tf: Fall time ... (S)
  • 3τ: Approx. 90% arrival time ... (S)
Fig.1 Output Volt.& Current at pulse drive

Function for Increasing Peak Power

This function is supported for all of our piezo drivers. An output peak current that is approximately 3 times the rated current is possible. For uses where the repetition frequency is slow and the average power is low (such as for positioning), high-speed startup is possible even with a small driver. For example, even though HJPZ-0.1Px3 is rated at 300 mA, a peak current of 900 mA is possible. If the average output current is 300 mA or less, it can be operated as a ±900 mA power supply. (See the figure below.) With this model, an output of 100 V allows a 1-μF piezo element to start up in 0.11 mS. For a repetition frequency when using pulse drive, operation of up to 1.5 kHz DC is possible on each of 3 channels.

Fig.2 Explanation of output of PZJ-0.1Px3

Bias Function

The bias function is an extremely convenient function that allows the direct current to be superimposed on the output voltage. By using the dial on the front panel to set the bias, you can move the output waveform freely within the rated output range. (See Figures (a) and (b) below.) If a setting exceeds the rated range, clipping occurs in the waveform.
(See Figure (c) below.) By using the bias function, it is possible to directly change the displacement reference position of the piezo element without changing the control voltage, which is effective for position adjustment and DC operation.
Also, by setting the control signal to 0 V, you can use only the bias function to use the product as a constant voltage DC power supply. HPZT models do not have a bias function, but you can apply bias at the stage of the external control signal.

Fig.3 Explanation of Bias Function