Heavy Duty Encoder - Hengstler Encoders

Technology overviewencodeR engInesThe engine in encoders is theinternal technology used to providethe signal required by the customer.Engine in its more familiar usewould be gas, hybrid, or electric.Engines in encoder technologywould typically be optical with amask, optical phased array, andmagnetic.Traditional optical absolute and incremental encoders have fourmain components: LED, disk, mask, and sensor. The disk willhave as many tracks as signals (A, B, Z, etc.), and the mask willhave windows for each track. The windows on the mask willalso have a size proportionate to the window size on the disk.In manufacturing, the mask is fastened directly to the sensor.This allows for one sensor to be used with several resolutionoptions.Phased array technology essentially averages several signals toincreases signal stability. Users can easily install these moduleswithout the need of precision fixtures and align disks without theuse of microscopes. Figure 8 shows the cross sectional sideview of the disk, and how the components are used to providea proper signal.This technology provides stable output during heavy shock andvibration, and opens up its use to oil rig, heavy vehicle, andmilitary applications.Magnetic encoders consist of a magnetized wheel, magnetoresistive sensors, and a signal conditioning electrical circuit.The wheel is magnetized mainly with 480, 512, and 600 polepairs. The amount of sensors and the signal conditioning circuitlogic combine to multiply or divide the number of pole pairs toresult in several different resolution options using only the threedifferent wheels.In absolute magnetic technology, there is a single pole pairrotating above a sensing element. The resolution is dependantupon the ability of the sensing element or ASIC (applicationspecific integrated circuit)In both absolute and incremental magnetic encoders, theengine allows for use in applications that are equal to or moredemanding than the phased array engine capabilities.Figure 8: Traditional Optical Encoder EngineCH. ACH. BCH. ZCH. UCH. VCH. WASensorA0B0A1An 120°e180°e90°e±1°m180°e120°eSensor Array180°eDiskMaskCCW Shaft RotationFigure 9: Phased Array TechnologyElectric SignalLEDDiskLEDSensing Circuit(Thin Film,Non-ContactingRotary Drum(Injection MoldedPlastic)Multipoles(PermanentlyMagnetized)Figure 10: Incremental Magnetic TechnologyIMIU MA.07Figure 11: Absolute Magnetic Technology