Conventional moving magnet galvanometer scanner
The conventional moving magnet scanner was originally conceived in 1976, but not manufactured until 1992, mostly because Neodymium “super magnets” were not available and cost effective until then. The conventional moving magnet design has several benefits, including the fact that electrical inductance is pretty low for a given torque constant, and there is little current required to hold a given position. Unfortunately, the motor physics that give this type of scanner low inductance also presents a limit to the attainable large-signal performance, because the coil must reside inside the magnetic air-gap and thus, coil resistance is relatively high. Therefore this type of scanner is mostly relegated to applications that do not require high large-signal performance. Laser marking is an ideal application for this type of scanner, because laser marking is a small-signal application. Laser displays that do not require super-high performance are another application.
It is important to keep in mind that the actuator portion of conventional moving magnet scanners has not evolved significantly since their introduction 1992. Moreover, whereas nearly all galvo manufacturers make scanners based on the conventional design, ScannerMAX offers three separate designs – each one optimized for a different set of applications.
(highest overall performance, similar cost) • Ideal for high-resolution imaging and high-speed laser displays
The ScannerMAX Saturn series uses a moving magnet rotor, whose design is generally stiffer than those of conventional moving magnet scanners, leading to reduced cross-axis wobble and higher resonant frequencies. For many applications, these factors allow ScannerMAX scanners to have better small-signal and large-signal performance. The Saturn stator design places the coil as close as possible to the magnetic air gap while still not residing inside the air gap itself. This coil placement allows the Saturn’s coil resistance to be 2 to 3 times lower than conventional moving magnet scanners, while coil inductance is approximately the same. Thermal conductivity (the rate at which heat is removed from the coil) is also improved compared to other known scanner types. The bottom line is that due to the stiffer rotor construction combined with a much lower coil resistance and similar coil inductance, the ScannerMAX Saturn series can be used in applications for which no other scanner is suitable, such as high-density OCT, high-speed displays and via hole drilling where conventional moving magnet scanners must be water cooled in order to be used. Despite the fact that the stator design involves stacked laminations and four separate coils, end-user and OEM costs are similar to those of conventional galvos.
(See US Patent 9,270,144, US Patent 9,530,559, China Patent ZL201420102156.6)
(high large-signal performance, lower cost) • Ideal for laser displays and certain low cost applications
The ScannerMAX VRAD (Versatile Rotary Actuator Device) series uses a moving magnet rotor whose construction is generally stiffer than conventional moving magnet scanners, giving all of the advantages of the Saturn noted above. The VRAD stator design places the coil well outside the magnetic air gap, allowing the coil area to be as large as desired. Because of this, coil resistance is a completely independent degree of freedom in the design. The motor physics that allow the coil resistance to be as low as possible also demand that inductance be higher than that of conventional moving magnet scanners – typically being 2 to 3 times higher for a given torque constant. However, since coil resistance is much lower, the overall coil impedance is not dramatically higher than conventional scanners, which means that, in the end, small signal performance is not significantly impacted. Due to the stiffer rotor construction and low coil resistance, this is a very versatile scanner, able to drive tiny mirrors as well as over-size mirrors, excelling particularly in areas where large-signal performance is required. End-user and OEM costs are lower than conventional moving magnet scanners.
(See US Patent 8,508,726, US Patent 8,963,396, US Patent 9,077,219 and China Patent ZL201210363949.9)
(conventional performance, lowest cost) • Ideal for 3D printers, laser displays, and automobile applications
The ScannerMAX ARC (Actuator with Rectangular Coil) series is our newest development. We consider it to be a new take on the old moving magnet scanner. Rotor construction is similar to conventional moving magnet scanners and therefore wobble and resonance performances are also similar. The main difference between the ScannerMAX ARC series and conventional galvos is how the coils are formed and where they are placed in the magnetic circuit. This difference allows this new design to have performance pretty similar to conventional moving magnet scanners, but having a manufacturing cost that is dramatically lower and easier to construct. Because of the similar performance but lower manufacturing cost, the ScannerMAX ARC series can potentially be used everywhere conventional moving magnet scanners are currently being used. However, due to the lower manufacturing costs, new applications become possible, or become more cost-effective – thus helping cost-sensitive laser and scanner applications to flourish. Consumer-level laser displays, 3D printers and automotive applications are examples. Up until now, consumer-level and point-of-purchase laser displays have not been widespread because of the overall cost of a scanning system. Scanning system costs also represents a significant portion of the cost of SLA-based 3D printers. And applications for self-driven- and assisted-driven-automobiles are currently being explored by automobile manufacturers. Because this new design delivers conventional-level performance at the lowest price possible, we believe that the ScannerMAX ARC series will enable these consumer applications as well as others, to become viable in the marketplace. For more information about ScannerMAX ARC scanners, please contact us.
(See US Patent 8,508,726, US Patent Pub. 20160233753, German Patent 202016000737.9 and China Patent ZL201620112019.X)