Piezo manufacturer selects reflective encoder

Physik Instrumente (PI), a German manufacturer of piezo-ultrasonic drives, has chosen the AEDR-8320 reflective encoder for use in a M-664KCEP vertical drive used in bio-handling dispensers.

The AEDR-8320 high-resolution surface-mount (SMT) reflective optical encoder, which provides precise positioning information and direction sensing, is suitable for industrial automation applications where space is limited.

PI's PILine of piezo-ultrasonic drives is an alternative to stackable motor concepts, especially in bio-handling dispenser applications where a compact high-speed actuator is needed.

Typically, the accuracy for automation and handling tasks required for these actuators ranges from 5 to 100 micrometres.

PI's M-664KCEP is a cost-effective vertical drive with PILine ultrasonic piezomotors.

Lining up eight or more of these vertical drives allows the independent vertical movement of pipettes to fill micro titre plates.

Matched with standard multiwell plates, the width of the individual actuator is only 9mm.

The M-664KCEP travels a distance of 50mm in 250ms to generate a push/pull force of up to 4N.

The resolution of the positioning sensor of 5 micrometres is fine-tuned to the application, to ensure positioning accuracy.

With dimensions of 6.5mm length by 4.2mm width by 1.69mm height, and a wide operating temperature range, Avago's AEDR-8320 encoder was found to be a good fit for PI's application.

Avago's AEDR-8320 series offers two-channel analogue output that provides a resolution of 180 lines per inch (LPI) for rotary and linear movement control.

In addition, its two-channel analogue outputs can achieve even higher resolutions through interpolation.

It can achieve resolutions of 2.2 micrometres to 10 micrometres for linear movement and from 4,096 counts per revolution (CPR) to 7,840 CPR for rotary sensing, using an external interpolation IC.

These high-resolution optical encoders also incorporate an LED light source and photo detector IC in a single leadless package, and use reflective technology to sense rotary or linear position.

They can be interfaced directly with most signal processing circuitries, to provide design-in flexibility and easy integration into existing systems.

Additionally, the AEDR-8320 series can be used with a reflective code wheel to sense rotary position and velocity, or with a linear code strip to sense linear position and velocity.

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