The march for miniaturization never stops as evidenced by portable products the size of a credit card that outperform some laptop and even desktop computers. Probably one of the most challenging markets in this quest for tinier gadgets is motors and motion control. Though still daunting, shrinking a semiconductor should be less of a burden because there are no moving parts to consider. But squeezing a motor and related control circuitry onto the head of a pin is another story.
One solution comes by way of PCBMotor, a Denmark-based company. Its patented technology can integrate both a motor and its required control circuitry directly onto the printed-circuit board, or PCB (Fig. 1). In addition to significantly shrinking the end design, another reported benefit is superior accuracy resulting from very fast start and stop times. Other advantages include a significant reduction in the amount of material and space required for the application, the ability to integrate multiple motors on one PCB, and the elimination of gears and connections, which yields very compact motors.
PCBMotor’s technology consists of two initial parts. The first step involves milling the motor stator out of the PCB, after which the stator hosts both the actuators and interfacing circuitry. The PCB may also support the driver. Second, the technology involves pressing the rotor onto the stator’s surface. As a result, the stator can deliver the mechanical output.
A travelling wave, which travels over the stator surface, acts as a flexible ring to produce elliptical motion on the rotor’s interface. In turn, the elliptical motion emanating from the contact surface drives both the rotor and the drive shaft.
After the first steps, the company mounts ceramic piezo components measuring 1 by 1 mm on the PCB (Fig. 2). Motor operation now depends on the friction occurring between the rotor and stator plus the amplitude and quality of the wave travelling on the stator. In the final design, the rotor can turn at speeds from 60 to 120 rpm while delivering torque levels ranging from 1 nm to more than 70 nm. Several factors determine torque levels in this topology such as stator diameter, the number of piezo components, and the rotor design and material.
AS PER THE COMPANY
It appears that any application requiring a motor, motion control, and an extremely frugal allocation of space will benefit from this approach, such as instrument dashboards, microscopes, audio mixers, cameras, and other motion apps.
“Traditional design methods use PCBs as motor controllers with connections to a physical motor located somewhere in the vicinity of the card,” says Henrik Staehr-Olsen, CEO of PCBMotor. “PCBMotor’s technology builds accurate and powerful motors directly onto the PCB itself, which significantly reduces application cost and introduces a world of new design opportunities.”
For the purposes of clarification and demonstration, the company compares its technology to a radio tuner. In a PCBMotor topology, multiple motors are deployable on a singular board. Each motor can tune to a different frequency. Reducing board space, a single driver switches each of the motors. Based on the high holding torque of the motors, they will maintain their positions during power-off conditions. Additionally, PCBMotor relies on standard components and established assembly techniques.