Method and rotary encoder for measuring the absolute angular position

p0001The invention relates to a method for detecting an absolute angular position of a rotatable component, in particular a shaft, at least two independent magnetoresistive pairs of sensors are premagnetized by at least one magnetic field source wherein in a first stationary unit comprising evaluation electronics, wherein the sensor pairs in the immediate vicinity of the magnetic field source are arranged and wherein at least a modulator, the position-dependent changes the magnetic flux of the magnetic field source at the location of the sensor pairs in density and / or direction, covered in a second rotatable with the component unit as a result of its rotation with the component, the sensors periodically and their arousal influenced, wherein the sensors are arranged in each case one pair of sensors so that they are covered by the cover elements of the modulator with an angle difference of a quarter of coverage period, and an angle sensor for implementing the method.

p0002Drives for rotating machine components, specifically Shaft drive with highly dynamic control behavior need for speed measurement, the state variables "rotor position" and "Speed". The number of required for controlling data points is the higher, the higher the dynamic behavior or the slower the speed of rotation of the rotating component or the shaft. With the advent of high-precision technologies, provide the ever higher demands on the synchronism of waves grows a need for ever more precise shaft drive controls. The precision of the control is dependent on the resolution of the angle sensor and the speedometer, which provide the input to the drive control system available.

p0003many different technologies were to measure Bauteilwinkel- or shaft situation developed in the past to determine this with ever greater precision, while there is a strong correlation between accuracy of Shot and the precision of it intended for measuring angular information.

p0004In order to increase the precision of the measured absolute angle of a rotating component, it is necessary, information from which the absolute angular position can be determined, according to condense on the rotating component on. However, the compression of discrete machine readable angle information is a limit set by the environmental conditions in which the angle information must be available, such as entry of operational flue dusts in the modulator-sensor housing. Although the reading procedure leaves the density with which discrete and independent angle information can be applied to rotating components currently ample room for even more precise absolute angle encoder as in the prior art, however, the components which carry the angle information are, or always sensitive, what a demand for higher robustness precludes. Therefore it is necessary to develop methods that allow to be able to absorb more and more precise angle, the robustness and reliability of the components used should also increase.

p0005Example of robust and high-precision angle encoders are in the <patcit id="pcit0001" dnum="US4039936A"><text>US Patent 4,039,936</text></patcit> and the <patcit id="pcit0002" dnum="DE19816696A1"><text>DE 19816696 A1</text></patcit> described. Characteristic for these to be considered as the closest prior art technologies to mount a magneto-resistive sensor to a static permanent magnet and so to place this sensor in the vicinity of a rotating ferromagnetic gear which rotates with the rotating member on an axis that is surface of the magneto-resistive sensor is periodically obscured by the teeth of the rotating gear and released again. Through the passing of a ferromagnetic tooth, the magnetic flux density changes in the magneto-resistive sensor, which will change its electrical resistance. The change in electrical resistance of the magneto-resistive sensors is used in the teachings of these two documents to determine the passage of the boundary between tooth and gap. In both documents, difficulties are described to modulate the change in electrical resistance of the magnetoresistive sensor through the arrangement of sensor, modulator and bias magnet so that the so-called zero crossing can be reliably and accurately determined. The zero crossing corresponds to the relative position of the sensor and the modulator, in which the sensor of a coverage passes through a tooth released by a gap. The difficulties described in the documents based on the observation that are near the surface of a carrying of magnetic field lines ferromagnetic material and also used reaching out in the previously used in the prior art spatial area around the modulator in the sensors without loss of function can, inharmonious components in the magnetic field through the modulator changes periodically occur, making it difficult to position detection of a passing modulator element, or burdened with a higher uncertainty premium. is proposed in the documents as a solution, to change the sensor itself so that the effects of the abovementioned distortions caused by placement of sensors coupled at different positions to be compensated relative to the modulator and thus the detection of a zero crossing takes place more precisely and in turn a square wave signal with a high temporal edge precision for incremental or absolute position determination is available.

p0006By doing so, although the zero crossing is very precisely determined and thus also the angle of the device at the time of the zero crossing, but the resolution of the angle determination is limited by the number of passing teeth. To increase the resolution further, already the modulation of a sinusoidal signal has been proposed by which the component position can be determined between two zero crossings, but high demands on the quality, particularly the harmonic poverty of the signal are provided. To increase the quality of the modulated sinusoidal signal by a passing pulling ferromagnetic element is in the publication<patcit id="pcit0003" dnum="DE19521617"><text>DE 19521617</text></patcit> proposed to bend the magneto-resistive traces on the chip surface, thus reducing also inharmonious components by density distortions on the edges of the tooth surface, which can interfere with the modulated signal quality in the magneto-resistive sensor. However, the proposed solution in this document represents a rather expensive solution to the problem of increasing the precision of the angle measurement.

p0007The object of the invention is therefore to provide a method for rugged and high-precision measurement of the absolute angular position of a rotating component is available, wherein the angle information, comprises on the component which is required for determining the absolute angular position of a considerably lower density, than the angular resolution the whole procedure complies.

p0008Another object of the present invention is to provide an angle sensor available which is based on the proposed method provides a signal from which the absolute angular position can be determined with high precision, the signal quality, which means harmonic poverty of the signal, equal good or better than in the prior art should be.

p0009According to the invention the object is achieved by an overlap of different sensor pairs with differing coverage period for rotation of the component and determine the absolute angular position from the comparison of the excitation intensity of different pairs of sensors and sensors with each other in each case one pair of sensors which sensors are placed directly on the at least one magnetic field source and be biased by a Magentfeld having the normal of the plane of each individual sensor an oblique component at an angle of 5 ° to 85 °, wherein the sensors are GMR sensors. Further advantageous embodiments result from the dependent claims.

p0010This method enables a simple and inexpensive construction, as well as a cost-effective retrofitting of existing rotating components, in particular shafts, since the component has to be provided only with at least a simple modulator itself, wherein the at least one modulator itself has no mechanical or electronic active components and far less exhibit elements for sensor coverage needs, as individual absolute angular positions are determined by means of this method. Due to the separation into two units, in a first unit, which is stationarily arranged in the vicinity of the modulator and containing the electronically active components and a second unit, which have only one having a component, in particular a shaft, co-rotating rigid component, it is with comparatively little effort possible to replace the electronics of the angle sensor, if necessary, or replace it with a more powerful electronics.

p0011In contrast to processes in which the absolute angular position is optically recorded by reading a code, this process is through the modulation of an existing magnetic field for use in areas where fly ash, precipitation fumes and other emissions are present, which the function of an optical interfere Shot process easily or can be put out of function even completely. The simple design of the modulator and the few required compared to the angular resolution covering elements the whole process is less sensitive to external interference.

p0012Even compared to methods in which an incremental or an absolute angular position by means of a rotating pole wheel is received, this method has the advantage that the rotating itself is not magnetized assembly against an external magnetic field is less sensitive, which interfere with a flywheel in its functionality or could completely destroy without the disorder can be seen with the component, in particular the shaft, co-rotating unit with the naked eye. Because often large machine components are positioned with the aid of magnetic grippers and / or assembled. In this assembly, the field strength of a magnet could be changed in a magnetic pole wheel, which has the consequence that the recording of the magnetic field strength of the magnet wheel for Shot to a distorted result and thus an incorrect measure would lead. In contrast, a ferromagnetic modulator are used, which can have a high coercive force, which is a measure of the resistance of a material to be magnetized in the presence of magnetic grippers without would be expected through the use of magnetic gripper substantial Shot deterioration ,

p0013The high and the necessary precision of the magnetic field modulation and sensor excitation depends by the shape of the modulator, its magnetic properties and the field direction of the magnetic flux at the location of the sensors in the inventive process. The angular resolution of at least one modulator can be relatively low compared to the possible angular resolution of the method, since the high angular resolution by a combination of the relative position of the various overlapping elements of at least one modulator each other and an electronic and / or digital electronic interpretation of using this method oberwellenarm modulated sinusoidal signal is achieved, which at the frequency of the sensors Überdedeckung oscillates synchronously by the modulator.

p0014For, surprisingly, it was found that the modulation of a sinusoidal signal in the magneto-resistive sensor is improved by this means harmonic poorer, can be modulated when the sensor is biased by a magnetic field having an oblique to the normal of the angle plate component, wherein a magnetic bias by a homogeneous magnetic field to an even higher harmonic poverty of the modulated signal leads.

p0015Likewise, it has surprisingly been found that such an arrangement of magneto-resistive sensor and preferred flow direction of the magnet used for biasing produces particularly low harmonic signals in the sensor plane normal and preferential direction are aligned parallel to each other.

p0016Furthermore, it was surprisingly found that the induced by the modulator variation of magnetic flux density and direction at the chosen field intensity in the selected volume can be adjusted by particularly oberwellenarm by both the flux density of the magnetic bias, the distance of the space volume of the modulator, in which the sensors are, and which is determined by material properties and geometry of the modulator ability to influence the magnetic flux to be coordinated. can be created by these successive tuning of the components a volume of space in the environment of operation of the at least one modulator in which inharmonic components of the periodic changes in the magnetic flux density and - direction largely minimized. By varying and optimization of these parameters, it is unnecessary to carry out the proposed in the art modifications to the sensors, which allows to access standardized and thus more cost-effective sensor elements.

p0017For use of the method of the magnetic mass storage devices known in the technology GMR sensors have proven to be particularly suitable, which serve as read heads for magnetically written on the magnetic surface of disk storage information. It has been found that GMR sensors particularly suitable for use in the process for few harmonics modulation of a sinusoidal signal of the invention are at an angle encoders because of their sensitivity interval. But there are also other magneto-resistive sensors in this method can be used by adapting the ratio of magnetic field strength to distance modulator, the spatial orientation and the geometric and / or material properties of at least one modulator.

p0018In the context of this document be understood to magneto-resistive sensors, such sensors, which produce an electrically usable signal from fluctuations in a magnetic field using the Hall, MR, AMR, CMR, GMR and / or in general XMR effect.

p0019Furthermore, it was found that the waveform may be further improved by shaping of the sensors periodically overlapping elements of the at least one modulator. Advantageously, a ferromagnetic modulator is used in the process for few harmonics modulation. Here, the parameters resulting permeability and geometrical shape of the modulator material to minimize the distortion factor of the output signal.

p0020It is also advantageous to measure the distance of the magnetoresistive sensors from the at least one modulator at the selected magnetic flux density of the at least one magnetic field source so that the magnetic field sensitive part of the magneto-resistive sensors is positioned so that this by the density and direction changes of the magnetic flux remains unaffected during rotation of the modulator, which in consequence of the discontinuous transition of air to ferromagnetic material in the vicinity of the surface of the at least one modulator undesired inharmonic components. Although the expression of the flux density and the magnetic field in -richtungsänderungen sensor is the smaller, the farther the location of the sensor is removed from the modulator, but impoverished by the distance at the same time the discordant harmonic components. In an optimal distance from the modulators is the discordant proportion of magnetic flux and -richtungsschwingungen negligibly small and caused by the modulator change amplitudes are still large enough for a magneto-resistive, especially GMR sensor, this with sufficient accuracy to modulate the electrical angle encoder signal can use.

p0021Likewise, it has proved advantageous, with different modulation frequencies, which preferably are in close proximity to excite different sensors in order to determine the angular position between two zero crossings of the modulation frequency according to the vernier principle. By using different closely spaced modulation frequencies, the number of possible uniquely determinable angular positions is less than the number of zero crossings in one revolution of the component or of the shaft far, it is possible to determine the angular position at a much higher precision than by the count, and identify individual zero crossings of a single modulation frequency is possible. The achievable in this way the subdivision of the angle is in the range of the mathematical product of the number of zero crossings of the two modulation frequencies. This vernier, sometimes called "Vernierverfahren" is, the skilled person well known and the tool technology.

p0022Preferably, a sensor pair are shifted by a quarter of the coverage period with the same period length and different pairs of sensors covered with different period lengths in the process each two sensors, wherein the different pairs of sensors are covered with period lengths, the difference between them a shorter coverage period length divided by the number of longer coverage periods is along an angular period of 2 π of the to be detected angle. The phase shift of a quarter of the coverage period of two sensors of a sensor pair is possible that the angular position between two zero crossings of the two phase-shifted signals can be clearly identified. The above-described difference between the two modulation signals to the zero crossing of the two modulation frequencies shifts to one another by a fraction of per coverage period of shorter coverage period up to one revolution of the component or the shaft at an angle of 2π of the zero crossing of the lower modulation frequency again simultaneously on a zero crossing of the higher modulation frequency applies. At the modulation frequency difference described above, there are along one revolution of the component or of the shaft only a single point at which the zero crossing of the lower modulation frequency exceeds the zero crossing of the higher modulation frequency. By comparing the angle information, which can be taken from a pair of sensors, the angle information of the other sensor pair, it is possible the overlap period to be determined unambiguously.

p0023To carry out the process of the invention is an angle sensor for detecting the absolute angular position of a rotatable component, in particular a shaft, are biased consisting of a first stationary unit comprising a transmitter, in which at least two independent magneto-resistive sensor pairs by at least one magnetic field source, the sensor pairs are arranged in close proximity to the magnetic field source, and wherein in a second rotatable with the constituent unit at least one modulator of the position-dependent changes the magnetic flux of the magnetic field source at the location of the sensor pairs in density and / or direction, the sensors as a result of its rotation with the component periodically covered and their excitement influenced, wherein the sensors are arranged in each case one pair of sensors so that they are covered with a phase shift of a quarter overlap period used.

p0024Advantageously, there is at least one magnetic field source comprises a permanent magnet and / or electromagnet, wherein the magnetisation direction of the magnet is arranged obliquely to the surface of the magnet in a particularly advantageous manner. In the optimization of the output signal of the angle sensor, it has been found that the magneto-resistive sensors are best biased by an obliquely magnetized permanent magnetic foil. This ensures that the various sensors are biased according to the manufacturing tolerances in the manufacture of permanent magnet film with a uniform, homogeneous and of equal height as rectified magnetization.

p0025In an arrangement of magneto-resistive sensors, an arrangement advantageous to produce a few harmonics signal is used, parallel to each other in the preferred flow direction of the magnet used for biasing and the sensor plane normal of at least one modulator.

p0026There are also other not specifically named here command and direction combinations used, the successive lead by voting to very few harmonics signals, for example, an oblique arrangement of the sensor level to the preferred direction of the magnet used for biasing.

p0027For advantageous bias of GMR sensors in the case of the oblique arrangement of the preferred direction of Vormagnetisierungsmagnetfeldes to the sensor surface, the angle of the obliquely magnetized permanent magnetic film is preferably used, or the obliquely magnetized permanent magnet and / or electromagnet 5 ° - 85 ° to the normal of the plane of each sensor, particularly advantageously approximately 45 ° to the normal of the plane of each sensor.

p0028The oblique bias the magnetoresistive sensors are held in a linear operating range, which means that the output signal with the fluctuation of the magnetic field is harmonic poorer. By a parallel alignment of the sensor surface with the plane of the co-rotating modulator and the slant magnetic bias of the sensor, the magnetic field lines meet obliquely on to the surface of the modulator. The periodic overlap of the sensors and released by the modulator, the magnetic field changes in the sensor, both in direction and in the density of the magnetic flux. The fact that the plane of rotation of the modulator is oriented oblique to the direction of magnetic flux, arises between bias magnet and modulator, a volume of the magnetic flux, in which the density changes and the changes in direction have mainly harmonic components and their inharmonious components are negligible.

p0029In the case of the parallel to the sensor plane bias performs Magnetfeldsensitivierungsschicht, which is usually mounted on the surfaces of magnetoresistive sensors, a magnetic bias of the sensor. This thus generated bias also means that the sensor is kept at an optimum linear operating range, which results in signals with a low distortion rate, equivalent to a low harmonic content comprising leads.

p0030In the event that the magnetic field source is a permanent magnet or an obliquely or perpendicularly magnetized permanent magnetic foil, it has proved to be advantageous if the magnet or the magnetic particles of the magnetized permanent magnetic foil AlNiCo, sintered or rare earth magnets are.

p0031To create a volume of space near the modulator, with the cover swings in the magnetic field strength, so the magnetic flux, or the direction of the magnetic flux in almost exclusively harmonious way, it has proved advantageous if the field strength of the local unmodulated sensor 1 mT to 300 mT, preferably about 15 mT.

p0032Regardless of the arrangement of the sensor of the magnet and the modulator may generally act XMR sensors, the sensors are Hall sensors, MR, AMR, CMR, GMRoder, but are particularly preferably in the angle encoder inventive GMR sensors.

p0033For further optimization of a few harmonics output of the angle sensor, the sensors are placed directly on the at least one magnetic field source. To arrange a magneto-resistive sensor on a magnet may be in accordance with the above advantageous embodiments to an eccentrically arranged on the pole face of an axially magnetized axially symmetrical bar magnet sensor. Particularly advantageous has proven when the sensors are applied directly to the surface of an obliquely magnetized magnet. Particularly good results were obtained when sensors were placed together on an obliquely magnetized permanent magnetic foil, wherein the permanent magnet film may consist of a continuous piece on which the sensors are arranged. When choosing the above parameters, it has proven to be advantageous and it has led to very few harmonics output signals when the sensors in a range of 100 microns - 5 mm, but more preferably from 500 microns 1.5 mm from the at least one modulator are mounted.

p0034In the arrangement of vertically arranged sensors, the sensor surfaces are arranged perpendicular to the passing modulator covering elements, it has proved to be advantageous if the sensors are disposed vertically on a vertically magnetized permanent magnetic foil or be placed on a vertically cut and perpendicularly magnetized bar magnet.

p0035Wherein at least a modulator, there may be two or more coaxial with the axis of the angle to be detected arranged ferromagnetic gearwheels with helical and / or Planradverzahnung. In the case of a gear with spur the magnetoresistive sensors are arranged parallel to the gear level close to the ring gear, the individual teeth of the gear, the sensors preferably alternately release and cover again. but it is also possible to arrange the sensors in parallel to the tangent of the end surface, so that upon rotation of the ferromagnetic gear per one tooth per one magneto-resistive sensor periodically comes close to and moves away from it again. In a Planradverzahnung the magneto-resistive sensors are preferably mounted parallel to the plane of the gear, but may also be arranged tangentially to the planradverzahnten gear.

p0036To achieve the different modulation frequencies for different pairs of sensors, it has proved to be advantageous if the at least one modulator consists of a group of three coaxial gearwheels, the gearwheels 64, 63 and 56 have teeth. By comparing the sensor signals which are generated by the gear with 64 teeth, with the signals generated by the sensor pair on the gear with 63 teeth, a unique angular resolution is already possible, in which the comparison of the zero-crossing position of the sensors an individual overlap period identified, and wherein the angular position within the coverage period can be determined from the signals of the sensor pairs, in which the two sensors are energized with a phase shift of a quarter of an overlap period.

p0037However, the number of teeth can be freely selected on the various modulators, as long as can be clearly inferred from an angular position therefrom a component revolution resulting movements of the zero crossings of individual teeth.

p0038The additional gear and the additional sensor pair, which sometimes passes through 56 an overlap period during a revolution, an additional redundant signal is present, confirming a determined by the evaluation position or negated this. In many industrial applications it must be expected that the signals by strong electromagnetic pulses, for example, by blasting machines or by sudden electrical switching operations, to be disturbed. Furthermore, it is possible through the use of a redundant signal, the angular resolution, which could deteriorate if used without redundant signals by temperature and aging-related drift of sensors used to maintain.

p0039In addition to the gear wheels, it is also possible to construct a modulator of a ferromagnetic disc, the disc having radial slots, indentations or elevations. The function of the sensors covering and re-releasing the teeth of the aforementioned gear assume here the radial slots, grooves or other. Using a disk, it is possible to influence by variations in the plate thickness, which is in the range of 0.1 mm to 1 mm, and thus the extent of ability to the magnetic field of the bias magnet to control the amplitude of the magnetic field vibration during rotation of the modulator , This results in a further optimization parameters for creation of a volume of space in which oscillates the magnetic flux density both in magnitude and in its direction with the modulation frequency. Even with the use of the ferromagnetic radial slots, grooves or having disc, it has proved to be advantageous if the disc has three concentric rings of equidistantly arranged slots, wherein the rings of 64, 63 and 56 slots are made and the angle information, as explained above , be determined.

p0040In the method according to the invention it is not necessary that the modulator is moved. Each angle information is derived also in the rest position of the modulator from the corresponding sensor signals.

p0041The invention is explained in more detail with reference to FIGS.

p0042It shows<dl id="dl0001"><dt>Fig. 1</dt><dd>a section of an end of a shaft centered arranged angle encoder with axial section through angle encoder, shaft bearings and shaft,</dd><dt>FIG. 2</dt><dd>the plan view of a shaft encoder disk and</dd><dt>Fig. 3</dt><dd>two oscillator diagrams of a single modulated magneto-resistive sensor, wherein the sensor in the individual diagrams was biased differently.</dd></dl>

p0043<figref idrefs="f0001">figure 1</figref> shows a longitudinal section of a successive arrangement of inventive angular encoder 1, a bearing housing 2 and a shaft 3. The angle sensor 1 consists of two units, the first unit has on a mounting plate 4 a transmitter 5, which is mounted on a first side of the first unit is three, and the magneto-resistive sensor pairs, 6, 7 and 8, which are arranged on a not illustrated here film permanent magnet on a second to the modulator / disc 9 facing side of the first unit. The first unit is fixed by means of a housing on the bearing housing 2 is not shown in the figure. The modulator / disc 9 is arranged on the head surface of the shaft 3 with a fastening element 10 and is fixedly connected to the shaft. The shaft 3 is supported in a double bearing 11, which is received in the bearing housing the second Upon rotation of the shaft 3, the modulator 9 rotates with it and changes the magnetic flux at the location of the sensor pairs 6, 7 and 8 by periodic coverage and released.

p0044<figref idrefs="f0001">figure 2</figref> shows the modulator disc 9 in a plan view. Clearly visible are three concentric rings with regular radially arranged trapezoidal slots 12, 13 and 14, which cover the magneto-resistive sensors periodically. The outermost ring of radial slots 12 has 64 slots, the middle ring of radial slots 13 has 56 slots and the innermost ring of radial slots 14 has 63 slots. The central receiving bore 15 with a variable inner diameter can be adjusted according to bemessender shaft 3 for attachment to the diameter of the shaft 3rd

p0045<figref idrefs="f0002">figure 3</figref> shows a diagram of the waveform of a magneto-resistive sensor at different selected direction of magnetization. The optimized waveform 16 shows a symmetrical periodic sinusoidal curve over several periods, from which the angle information can be determined by measurement of the amplitude at any one time. By contrast, the waveform 17 of the sensor which has been biased with a deviating from the optimum magnetization direction, significant asymmetries equivalent high THD comprising, on. In the diagram, the waveform 16 a nearly ideal sinusoidal curve on, however, the waveform of the signal 17 is clear to the ideal sinusoidal shape distorted in the positive half-waves, which is synonymous with a non-negligible harmonic content or a high THD.

p0046While the present invention has been described and illustrated with reference to the foregoing preferred embodiment, it will be apparent to those skilled in the art that changes in form and details are possible without departing from the scope of the invention as defined in the following claims.

p0047If MR sensors or magneto-resistive sensors are taught in this document, so therefore are equally meant the technologies MR, AMR, GMR, TMR, CMR, reverb and generally XMR sensors.

p0048Similarly, the frequency ratios of the modulators or modulator sections can be selected to each other, provided that this a unique angular position can be determined in any other relationship.

p0049Under an overlap period of the angle is meant in accordance with the inventive teaching, the modulator between the beginning of a sensor cover by a cover element of the modulator, subsequently, the sensor coverage itself, the beginning of the re-release, re-release and until the next start of a next sensor coverage by an adjacent tooth, or an adjacent cover element, passes through. The number of overlapping periods per sensor, which is covered and again freely given by the at least one modulator, along a complete component revolution corresponds exactly to the number of overlapping elements used for sensor coverage of the modulator.

p0050Those skilled in the art will appreciate that for identifying the angular position of the component is a number from 0 until 2 indicated π, wherein the position of the component π coincides in position 0 to the position 2, with the difference that the component or the so-coupled modulator at has made one revolution of 2 π a complete revolution. A distinction of this is the component or modulator circulation according to the above angle relationship of a component or modulator round of one period 0 to 2 π, which does not refer to a component in circulation, but the angle crossing of along an overlap period in accordance with the above definition. In both definitions behaves the angle which is given to 2 π normalized in the dimension of 0, linearly proportional to the actual distance angle of the component or the coupled modulator.

p0051The coverage period may in the method and in the angle sensor according to the invention have a ratio of overlap length to re-release length, which is less than 1, equal to 1 or greater than 1, wherein under the overlapping length of the angle is meant which the component or the modulator can pass through without that the sensor is again freely given and accordingly re-release length of the angle, which can be passed from component or modulator, without the sensor is covered. The sum of overlap length and re-release length corresponds to the coverage period. This means that the pulse-pause ratio, often duty or duty cycle called, in the process is freely selectable and can be varied to optimize a few harmonics signal.

p0052The sensor coverage can switch to again freely given by covers in the process continuously. A binary change from overlap to re-release means thereby again freely given by covering an extreme position in the parameter optimization as a continuous smooth transition. In any case, the overlap period length is uniquely defined by corresponding angular positions according to the above definition.

LIST OF REFERENCE NUMBERS

p0053<dl id="dl0002" compact="compact"><dt>1</dt><dd>angle encoder</dd><dt>2</dt><dd>bearing housing</dd><dt>3</dt><dd>wave</dd><dt>4</dt><dd>mounting plate</dd><dt>5</dt><dd>evaluation</dd><dt>6</dt><dd>magnetoresistive sensor pair</dd><dt>7</dt><dd>magnetoresistive sensor pair</dd><dt>8th</dt><dd>magnetoresistive sensor pair</dd><dt>9</dt><dd>Modulator / disc</dd><dt>10</dt><dd>fastener</dd><dt>11</dt><dd>double bearings</dd><dt>12</dt><dd>Ring of radial slots</dd><dt>13</dt><dd>Ring of radial slots</dd><dt>14</dt><dd>Ring of radial slots</dd><dt>15</dt><dd>Aufnahmebohrung</dd><dt>16</dt><dd>optimized waveform</dd><dt>17</dt><dd>not optimized waveform</dd></dl>