DE102004011146A1 - High resolution angle sensor has housing with optical sensor reading two component plastic disc with sealed angle markings - Google Patents

Abstract

A high resolution angle sensor has a housing (3) containing a moulded plastic disc (1), made of two different plastics with a structured side containing sealed metallisation or different plastic angle markings that is rigidly fixed to a test object (2) whose position is measured by an optical detector (4).

Description

The The present invention relates to a measuring sensor, and more particularly The present invention relates to an opto-electronic rotation angle sensor.

Rotary position sensors, Also called rotary encoders, are used in a variety of applications Automotive manufacturing, industry and research used to adjust the angular position to detect during rotational movements. Examples are the steering angle detection in the vehicle for Driving stability systems, the position detection of rotating elements in machines or the measurement of the angle of inclination of a pendulum.

Out literature (for example Hoffmann, Jörg: Handbuch der Messtechnik, Carl Hanser Verlag, Munich, Wien, 1999, p. 306 ff.) Are a number of possible principles of action of Encoders known. Here are mainly optical and inductive Followed principles.

For the optical Principles become primary transparent discs (mostly made of glass) are used, which for example are provided with a structured masking layer of metal.

there Two types of sensors can be realized: Incremental encoders and absolute measuring sensors.

at Incremental encoders are the measurement of a relative position change by dividing a structure on a circular disk into a plurality reached by strokes. Absolutely measuring sensors are structured with Slices realized which capture an absolute position, the is stored as coding on several parallel tracks.

to Evaluation of both possibilities be reflected light or Transmitted light method used.

When Inductive methods are the resolver method in the prior art and the inductive pulse generator known.

resolver are transformers with one rotor winding and two by 90 degrees staggered stator windings. Upon rotation of the rotor can be determined by the induced voltages in the two stator windings to the current absolute position to be closed.

at Inductive pulse generator is a wound with a coil permanent magnet to one on a lateral surface structured rotating disc of metal (for example, a Gear) approximated. It changes periodically the distance from disk to magnet, being in the coil a voltage with rotational speed-dependent amplitude is induced.

Also exist arrangements in which between permanent magnet and toothed disk Field plates or Hall elements are arranged showing the change detect the acting magnetic flux density.

The usual Rotary encoders, in particular the optical encoders with absolute or incremental angle detection, but have the disadvantage of that the requirement for a necessary high resolution of the Angle at the same time small volume of the encoder and at the same time very Great Manufacturing costs currently can not be realized.

outgoing from this prior art, the present invention is the Task based, a simple, inexpensive and at the same time high-resolution encoder and to provide a method of operating the same.

These The object is achieved by a rotary encoder according to claim 1 and a method for operating a rotary encoder according to claim 25.

The present invention provides a rotary encoder having the following features:
an information carrier having a plurality of tags, wherein a material of the information carrier corresponds to a material of a tag, and wherein a tag is an optically detectable embodiment of information from which a position of the information carrier is derivable; and
an optical detector for detecting the mark, wherein the information carrier and the detector are arranged rotatably relative to each other and wherein a rotation angle of a relative rotation between the information carrier and the detector can be determined by a detection signal.

Furthermore, the present invention provides a method of operating a rotary encoder, wherein the rotary encoder comprises an information carrier having a plurality of license plates, wherein a material of the information carrier corresponds to a material of a license plate and wherein a flag is an optically detectable embodiment of an information from the one Location of the information carrier is derivable and comprises an optical detector for detecting the flag, wherein the Infor mation carrier and the detector are rotatably arranged relative to each other, and wherein a rotation angle of a relative rotation between the information carrier and the detector can be determined by a detection signal, comprising the following steps:
Turning the information carrier; and
Detecting a mark with the optical detector.

Of the The present invention is based on the finding that an information carrier a material can be formed, the material of the license plate equivalent. For example, is the information carrier one transparent plastic disc, the license plates also match the material of the plastic disc and are thus manufacturing technology easy to implement. Furthermore, each number plate corresponds to one optically detectable embodiment an information from which a position of the information carrier can be derived is. For example, is the mark in the form of a depression or an increase over one surface of the information carrier may preferably be formed by a suitable pattern of (several) such depressions or elevations an absolute positional value of the tag is encoded on the information carrier or information about an incremental rotation of the information carrier are derived.

One such coding is comparable to coding, for example of information on a CD (CD = Compact Disc), in which as well Information through raises or depressions can be stored on a surface of the CD. Similarly also uses a coding technique known from DVD technology be that opposite the coding process for CDs a higher information density due has multiple functional layers on DVDs. Will now be the information to be encoded, from which the position of the information carrier is derivable, preferably thus stored in radial form on the information carrier space-saving information arranged on the information carrier from which the position of the information carrier can be derived very easily is. Preferably the individual license plates distinguishable applied to the information carrier be, for example in a binary-coded form. Here can the location of the information carrier then merely determined by one of the flags detected and the preferably binary-coded information is decoded, from which then immediacy the position of the information carrier derivable is when the individual binary-coded identifier distinguishable from each other. To derive the situation is, for example only an evaluation of the detection signal necessary, for example in an interference pattern electronically detected by the detector consists. Alternatively you can the license plates are indistinguishable, but from that by counting of runs from indistinguishable License plate and the knowledge of the distance of the individual license plate one Calculating a rotation angle or the rotation speed is possible around the information carrier was rotated relative to the optical detector.

Of the inventive approach offers the advantage of a cost-effective and easy-to-implement rotary encoder. Thereby, that a preferably used manufacturing process already mature and already used in mass production, can be produced with the approach proposed here very cost-effective information carrier, the same time the possibility offer, with a high degree of miniaturization and an im Compared to conventional Encoders high information density on the information carrier too to provide highly accurate angular resolution. As a result, the already known and tested and / or optimized Manufacturing methods for producing the rotary encoder are applicable, can be thus a simple, inexpensive can be produced as well as a high-resolution encoder. Another advantage is that the optical detector also cost feasible is because he is on the working principle of the widely applied and optimized Detector for the selection method of CDs or similar methods are based can. This also results in a simple, fast-available, high-precision and cost-effective Method of operating the rotary encoder possible.

According to one Another aspect of the present invention is the information carrier a disc, which comprises an optically transparent plastic material. This offers the advantage, analogous to the base material of CDs a cost-effective and compared to conventional ones Encoders highly accurate information carrier provide.

According to another aspect of the present invention, the information carrier comprises an information carrier surface, wherein a label comprises a recess in the information carrier surface or a projection from the information carrier surface. If, for example, the information carrier is made of an optically transparent material, the recesses or elevations result in a transmission with a light to runtime differences of the individual light beams resulting in a phase shift of the different light beams and this in turn results in a detectable interference of the individual light beams. Such an embodiment of the information carrier offers the advantage of, for example, the information carrier by an injection molding or inexpensively to produce an injection compression molding process, since these methods are already used in the production of CDs, and thus are technically mature and cost-effective.

According to one Another aspect of the present invention is the information carrier surface and the mark covered by a cover layer. It can the Covering layer, for example, a metallic or reflective Include material. By such an information carrier can For example, again on the technically mature manufacturing process used by CDs in which also that side of the information carrier, in the information is physically imprinted by the reflective Material are covered. Furthermore, the reflective material preferably good optical mirror properties, which is advantageous through the possible Use of a simple optical detector in the evaluation the information on the information carrier. According to one Another aspect of the present invention includes the information carrier Material having a first optical refractive index and the cover layer a material having a second optical refractive index, wherein the first optical refractive index different from the second optical refractive index is.

This offers the advantage only by the use of two materials with different optical refractive indices (for example two plastic layers with different Brechindices) to an optical behavior of the information carrier achieve that, similar favorable Mirror properties like comprising an information carrier provided with a metal layer. This is the case in particular when the information carrier is under a weird one Incident angle is irradiated with light, and the information carrier one higher optical refractive index has as the cover layer. through beam then namely the light first the information carrier, it is due to the refractive index stage between the information carrier and the cover layer partially or almost totally reflected, resulting in thus like a reflection on a metallic or reflective Covering layer affects. However, if the cover layer is being used from the other material (preferably plastic material) with formed another refractive index, this offers the further advantage that such an information carrier is better to recycle, because a separation of metallic parts and plastic components of such coated information carrier omitted can.

According to one Another aspect of the present invention differs first optical refractive index and the second optical refractive index by less than 50 percent, preferably the first differ optical refractive index and the second optical refractive index to LESS than 20 percent. This leaves make sure that, on the one hand, a sufficient optical Effect of the difference between the optical refractive indices of the information carrier and the cover layer is accessible, but on the other hand, the Processing of the materials to be used for the cover layer and the information carrier easy to handle. Furthermore can make a difference by such a choice of optical refractive indices an optical length between light rays that pass through an elevation or recess, and rays of light that do not go through the same finer tuned be, since with a smaller difference in refractive index a smaller optical delay differences can be formed. In a simplification also the heights of Elevations or the depths of the recesses are magnified, which has a simplification of manufacturability, since a coarser one Structuring the surveys and recesses are used can.

According to one Another aspect of the present invention includes a tag a plurality of part marks. Each of the sub-flags can thereby include one or more surveys or recesses. These Most of the partial identifiers of the license plate may be based on preference from a rotational axis of the information carrier on the same in the radial direction be arranged. Such an arrangement of the plurality of sub-flags the mark offers the advantage that only a narrow Segment of the information carrier is to be marked with the indicator. This is possible the spatial Space consumption of the plate, for example, compared to one Arrangement of the individual partial identifiers of a license plate on one significantly reduce the concentric circle around the axis of rotation.

According to one Another aspect of the present invention includes a first identifier first number of sub-codes and a second code one second number of sub-flags, wherein the first number of sub-characters of the second number of sub-flags. This is it possible, by a uniform number of sub-flags of each of the different tags a significant simplification of the evaluation of detected characteristics to enable.

According to another aspect of the present invention, a first partial identifier of the first license plate has a higher priority than a second partial license plate of the first license plate, and a first partial license plate of the second license plate has a higher priority than one second partial identifier of the second license plate, wherein the first partial identifier of the first license plate and the first partial license plate of the second license plate have a substantially equal distance from the axis of rotation of the information carrier, for example the center of the disc. As a result, a simple arrangement of the optical detector is possible, so that the detector detects all the sub-characteristics of the individual license plates, which have a substantially equal distance from the center of the disc. A mobility of the detector or a light source for reading or for reading the information of the information carrier necessary number of light sources and detectors can therefore be reduced, which has a cost-saving effect in the production of the encoder.

According to one Another aspect of the present invention is the first part identifier of the first license plate and the first partial license plate of the second license plate Characterized by a survey or a recess with each other connected. This allows for example, adjacently arranged part identifiers or elevations and recesses of the individual substructures by a longer bar or a longer one Digging together, being a coarser and more thus simpler manufacturing process is applicable because not more each submarkion individually, but taking into account the expression of Partial license plate arranged adjacent subparagraph produced can be. Alternatively you can in this way, also partial identifier of a single license plate be connected to each other.

According to one Another aspect of the present invention is the information a binary coded Location information and a partial identifier of a license plate one bit the binary-coded position information. This offers the advantage of being distinguishable in a simple manner To provide characteristics from which the location of the information carrier derivable is. additionally can in the evaluation of the detected position information to a analog-to-digital conversion (A / D conversion) of the detected position information be omitted, since these are already recorded in digital form. This offers the further advantage that by such Rotary encoder again significantly save manufacturing costs.

According to one In another aspect of the present invention, the information carrier has a number of marks on which a maximum number of each other distinguishable binary-coded Location information corresponds. This offers the advantage of having a Number of identifiers exactly matches a number, which by the binary-coded Structure of the license plate can be displayed. For example, the Location information represented by six bits in binary, can open the information carrier 64 distinguishable markers are provided, which through a relationship between resolving power of the Marking and spatial Optimizing the space requirement of the license plate.

According to one Another aspect of the present invention includes the optical detector at least one light source for outputting light of a predetermined one Wavelength, a lens and a sensor element. This offers the advantage, in a simple way and the information contained on the information carrier is to read out with a technically simple optical detector too can, wherein the technology used from the read-out unit of CDs resorted can be.

According to another aspect of the present invention, a recess has a depth or an elevation has a height that is in a predetermined relationship to the predetermined wavelength of the light of the light source. This offers the advantage, depending on the depth of the recess or the height of the elevation, of achieving a spectral interference pattern between the individual partial identifiers. Furthermore, by varying the depth of the recess or the height of the elevation, an interference may be generated which, for example, enables different interference patterns to be generated using the predetermined wavelength. If, for example, by varying the depth of the recess or the height of the elevation, different color shades or graduations (eg light, gray, dark) are possible, these in turn can advantageously be used to encode information. This can be used, for example, to assign different information values to the different color gradations, whereby the information density per unit area can be further increased. For example, more than one binary information may be associated with such multi-level coding if each color level is assigned its own information value. For this purpose, advantageously a first and second threshold value for the assignment of the detected color level to at least three different associated information values in the optical detector can be chosen such that a detected interference pattern can be evaluated more than just binary (eg 3-level). In such an application, however, the detector should be designed to perform a so-called interpolation of the individual detected interference levels (ie the different detected gray levels). For this, however, it is usually necessary to include an analog component in the detector, since now more a purely digital evaluation is usually no longer feasible and only about the analogous evaluation of the brightness level of the interference pattern a digitization of the detected information is possible. Analogously, however, interpolation can take place even in the case of a simple light-dark interference pattern without the gray levels in order, for example, to be able to better compensate for interference in the readout method.

According to one Another aspect of the present invention includes a tag a first part identifier that contains information about an absolute part Location of the information carrier and a second part identifier from which information about a incremental change of position of the information carrier can be determined. This offers the advantage of being the current location the detector does not need to be known when commissioning the encoder, At the same time, however, the evaluation in operation is not always an absolute position of the information carrier needs to recapture. Such an information carrier offers thus a favorable one and quick readability, since both information about the absolute position as well as information about a relative rotation of the information carrier present on the same or derivable.

According to one Another aspect of the present invention includes the first part identifier binary coded Information on a substantially concentric circle are arranged about the axis of rotation of the information carrier and the second Part identifier a plurality of indistinguishable characteristics, on a substantially concentric circle about the axis of rotation of the information carrier are arranged. Advantageously, the first part identifier and the second part identifier arranged such that the radial distance of the first circle from the axis of rotation of the radial distance of the second Circle is different from the axis of rotation. By such Arrangement leaves thus realize a significant simplification of the reading of the information carrier, because now to read the information about the absolute position of the information carrier only a light source can be used, with the help of which the first Part identifier can be read serially, while preferably indistinguishable features of the second part identifier, for example can be read with a second light source. Opposite one radial arrangement of the binary Information of the individual part marks saves such Arrangement thus the radial movement of a light beam over the Part identifier or the use of a plurality of light sources and detectors to detect each bit of the sub-tag. This therefore results in a reduction of the required manufacturing costs for the encoder.

According to one Another aspect of the present invention comprises the information carrier a arranged eccentrically to a rotational axis of the information carrier Mass unit. Through this additional eccentrically arranged mass unit, the information carrier, for example, by align gravity in one direction and thereby, for example as a simple tilt or rotation angle sensor with freely movable information carrier and use a detector connected to a device.

preferred embodiments The present invention will be described below with reference to the accompanying Drawings closer explained. Show it:

1 an exploded view of a preferred embodiment of the encoder with open housing halves;

2 a representation of a rotary encoder with mass acted disk for detection of the angle of rotation with respect to the horizontal;

3 a schematic representation of a beam path in transmitted light measuring method;

4 a representation of a projected example on photodiodes brightness profile when illuminated by the imaged pane section;

5 a schematic representation of a beam path when the illumination of the disc in the transmitted light process;

6 a schematic representation of a beam path in a method with reflected light;

7 a schematic representation of a beam path in the disc in a method with reflected light;

8th a schematic representation of a beam path in the transmitted light method without collimation of the light through a lens;

9 a schematic representation of a beam path in a method with reflected light without collimation of the light through a lens;

10 an exemplary representation of a coding option for an angular position on the disc;

11 a representation of different structuring options on the disc.

In the following description of the preferred embodiments of the present invention are for those in the various Drawings shown and similar acting elements same or similar Reference numeral ver applies, with a repeated description of this Elements is omitted.

1 shows an exploded view of an embodiment of a rotary encoder according to the invention with open housing halves. A disk 1 (Information carrier) is in a housing 3 with at least one bushing for a shaft 2 guided. In the case 3 is, for example, an optical-electronic evaluation unit 4 , for example, from one or more light sources and a suitable detection device z. B. a photodiode, a plurality of photodiodes or a photodiode array with the corresponding optical elements and is arranged such that a defined region of the (preferably structured) disc 1 is read out according to an angular position. As the light source, for example, one or more laser diodes can be used with a predefined wavelength. The detection can be done for example via photodiodes or photodiode arrays or with the aid of 1D and 2D micro-scanner mirrors. Also, the beam of a laser diode can be divided into a plurality of beams by suitable optical components such as gratings. In addition to the light source and the detection device, for example, other optical components such. As lenses, prisms and mirrors for beam guidance required. The angular embodiment can be scanned by reflected light or transmitted light. Information on the disk can be arranged such that the current position is stored as a digital pattern (ie, angular embodiment) at the scanned location.

For a measurement of the rotation angle of the housing 3 the encoder with respect to the horizontal can also use the method described below. This is the target of the disc 1 due to the gravitational force always in one position. This is for example a sprayed and structured plastic disc 1 according to the schematic representation in 2 rotatable in the housing 3 the encoder stored. This is the disc 1 made such that the center of mass 5 outside the axis of rotation 2 ' lies. The shift of the center of mass 5 the disc 1 can be achieved or enlarged, for example, by encapsulation of an eccentric metal piece.

The rotatable in the housing 3 stored disc 1 always aligns with the gravitational field in one position. Will the housing 3 rotated, the angle of rotation of the housing can be 3 through the angularity of the disc 1 and the optical-electronic evaluation unit 4 read.

The angle detection by means of laser and photodiode in the transmitted light method is exemplary in 3 shown. That of the laser diode 41 emitted light 46 will be in a look 42 collimated and hits with parallel beam through a diaphragm 43 on the textured disk 1 , When examining the structured pane 1 arise due to the structuring in the form of recesses 11 or surveys 12 the disc 1 Phase shifts of the individual light beams or waves, which lead to interference of the light waves. After focusing through the second lens 44 the light intensity is modulated according to the structure pattern. In this case, the intensity of the light beam can be extinguished locally by interference or greatly reduced. Alternatively, a different gradation of the interference can be generated by the depth of the recesses 11 or the height of the elevations 12 is varied. By means of this variable modulation or interference of different intensity, therefore, different brightness patterns can be generated and these can be assigned different information. These intensity maxima and minima, exemplified in 4 shown schematically, can by one or more photodiodes 45 be detected. Alternative to the recessed structure 11 in 3 The microstructure can also surveys 12 and these in a similar way as recesses 11 be used.

Are the individual structures through a plurality of wells 11 or raises 12 may also have a different intensity of intensity of each interference by a different proportion of wells 11 or raises 12 towards non-deepening or non-elevated areas. Depending on the proportion of recessed 11 or raised 12 Areas can thus have a share of light with the through the depression 11 or the increase 12 caused phase shift, which results in a corresponding weight of the phase-shifted light in the total amount of interfering light.

The ray path of the light 46 in the disk 1 in transmitted light is schematically in 5 shown. To extinguish the light 46 due to interference, the phase shift of the individual light waves must be half the wavelength of the laser starting from the laser diode 41 be. This is realized by having in the disc 1 at the respective place recesses 11 ' (please refer 4 ) or increases 12 ' (please refer 4 ), similar to those of a CD. The necessary thickness d of the depressions 11 ' or raises 12 ' is calculated according to the optical laws from the wavelength of the laser beam and the refractive index n _{S of} the planar disk 1 and the license plate. Therefore, the thickness d results, for example, for a like in 5 illustrated vertically irradiated planar disk 1 with x = 1,3,5, ...., n _S = refractive index of the plastic and λ = wavelength of the laser too

Because interference creates an intensity minimum, it must be ensured that a certain area is covered by planar and recessed 11 ' or sublime 12 ' Areas of the disc 1 is trained as in 4 is shown. These should be roughly evenly distributed within the structure (that is, the indicator or partial indicator).

The angle detection by means of reflected light is in 6 shown. In this case, the back of the structuring (ie the recess 11 or survey 12 ) with a thin reflective metal coating 13 z. As aluminum, which is applied for example by PVD coating provided. The light 46 the diode 41 is through the lens 42 collimated. The parallel light hits through a semitransparent mirror 47 and a panel 43 on the disc 1 and gets through the metal coating 13 reflected on the structured side. The reflected light is passed through a suitable device 47 , such as a semitransparent mirror, deflected and again through a lens 44 bundles and interferes in their focal point by using a photosensor 45 is arranged.

The beam path of the light in the disk in the method with reflected light and vertical light incidence is schematically in 7 shown. As already described in the transmitted light method, the phase shift of the light is realized by a longer optical path in the denser medium. Because the light 46 on the metal coating 13 is reflected, it passes through the plastic disc 1 twice. This results, for example, for the thickness d of the recesses 11 ' or increases 12 ' with a vertically incident light beam with x = 1.3.5, ...., n _S = refractive index of the plastic and λ = wavelength of the laser the following dependence:

Both transmitted light and reflected light can also affect the collimation of the light 46 the laser diode 41 through the first lens 42 be waived. The light no longer hits the disc at a constant mean angle α 1 , When the lens is illuminated 1 arise nevertheless due to the structuring 11 or 12 Phase shifts of the individual light waves, which lead to interference. This will after focusing the light beam in the lens 44 the light intensity corresponding to the pattern of structure through the recesses 11 and surveys 12 modulated. The beam path in transmitted light is schematically shown in FIG 8th shown. When reflected light, the light passes in accordance with the beam path in 9 , To detect the angular position by means of reflected light, the light 46 the laser diode 41 both at an angle α with respect to the disk 1 , as well as with the angle α = 0 ° perpendicular to the disk 1 come to mind.

The advantage of the invention described over conventional methods is in the finest super-resolution structures extremely cost-effective production of the disc 1 as an angular embodiment by, for example, micro injection molding and PVD metal coating in a similar manner as is known in the CDs. Due to the high packing density of the information on the disc 1 a very high angular accuracy can be achieved with a small construction volume. In addition, other elements can be produced during injection molding, such as the axle, bearings, gears, etc., which can then form an integral unit with the disc as an information carrier.

In addition to the described manufacturing process, the disc 1 also be made with the 2-component injection molding. In this case, the optical contrast of the angular embodiment is produced by combining two different refractive indices, for example by the application of a cover layer which has a different refractive index than the material of the disc, or a transparent or absorbent plastic.

The angle information on the disk 1 can be arranged such that each measurable position is determined by a clear coding. As an example, the coding may be appropriate 10A on the plastic disc 1 be arranged. In this case, a unique information consisting of several bits is stored radially on the disc for each measurable angle. In 10A Each of the possible 64 positions is coded by a 6bit number. The dark and bright fields symbolize the structured and unstructured areas of the disc. This will be on the disc 1 the positions at which intensity minima are to be created are provided with diffractive optical structures, the areas with intensity maxima remain unstructured. This structuring option is also applied to CDs under the term "pit and land" structuring. Depending on the resolution of the encoder, the bit width of the information ge arbitrary ge be chosen.

Alternatively, the information on the information carrier can also be applied to the disc by means of a marking, as shown in FIG 10B through the structures 1002 and 1004 is shown. Here, by the reference numeral 1002 For example, a binary coded information about an absolute position of the information carrier on the second-extreme track 1006 arranged. This information is preferably on the second outermost track 1006 of the information carrier arranged to be read, for example, by a single, fixed photodiode, which is the second outermost track 1006 scans. In other words, the information is serial, that is, in the direction of the circumference of the second outer track 1006 arranged. The identification of the position of the information carrier is then by reading a sequence of contiguous sub-marks (ie, for example, recesses or elevations, which are indicated by dark areas in 10B are marked). In contrast, by the reference numeral 1004 a plurality of indistinguishable features, such as a series of similar protrusions or recesses in the outermost track 1008 marked in the illustration of the 10A correspond to the least significant bit of the binary code. In contrast, here are the individual features on the extreme track 1008 spatially separated, like those through the structure 1004 is illustrated with two features in the form of dark areas compared to two separation fields in the form of bright areas. These features can be used for incremental angle detection. It can thus be said that the structure 1002 , which characterizes the absolute position of the information carrier, shorter, ie more compact, can be designed as the structure 1004 , via which the incremental angle change of the information carrier can be recognized.

Unlike the in 10A illustrated radial orientation is the information of the structure 1002 however, disposed in the direction of the circumference of a concentric circle about the axis of rotation of the disk, passing through each one of the structures 1002 an absolute position is identifiable. This structure 1002 may for example be formed in the same way as the radial structures on the in 10A shown disc, ie they can be formed as elevations and recesses. In this case, however, the information is no longer arranged radially on the bill, but in the direction of the circumference of the concentric circle 1006 ,

Now, if the disc, ie the information carrier rotated, can be through the detector, the structure 1002 and the features 1004 read. For a fine angle subdivision, the information from the features on the outermost track 1008 for example, by counting how often such a feature passes the detector. Such an approach to angle measurement has the advantage that not only a highly accurate and finely granulated angular resolution through the incremental angle measurement can be realized, but that even more information about the absolute position of the disc is recognizable and thus no errors in the angle measurement occur, for example the detector is turned off and the disc then rotates. The advantages of incremental angle measurement can therefore be combined with the advantages of absolute angle measurement. This is technically feasible, since it can be used on known methods, such as those used for the production of CDs. As a further aspect can be mentioned in the above approach that here preferably only two adjacent light sources and two adjacently arranged photodiodes need be used and no cost-intensive device for Laserstrahlablenkungen or six laser diodes with six photodiodes (ie, a photodiode array) for reading the radially arranged information needed. A slight disadvantage here would be to mention that the disc relative to the detector by at least a distance on the second-outermost track 1006 should be moved, the length of a complete structure 1002 corresponds to the information in the structure 1002 completely decoded coded absolute position. It should be noted, however, that such a rotation is to be regarded as uncritical, since at present feasible component dimensions and structuring limits almost always (for example, by vibrations) sufficient relative rotation of the disc to the detector can be ensured before a current measurement so that a complete structure is read.

As a diffractive structure 11 or 12 for example, individual recessed 11 ' or sublime 12 ' Points or bars are used, as in the pictures of 11 is shown schematically. In the process different points can be points in arrays 11 ' and 12 ' or parallel bars along the circumference 11 '' and 12 '' or beams radially 11 ''' and 12 ''' Arrange. Furthermore, it is possible to realize the diffractive structure, for example, by one-dimensional or multidimensional grids.

For measuring the angle of rotation of the housing 3 the encoder with respect to the horizontal by means of gravity can be described method also use. This is the sprayed and structured plastic disc 1 rotatable in the housing 3 the encoder stored. In this case, the disc is made such that a center of mass 5 outside the axis of rotation 2 ' lies. The disc 1 can be made for example by molding an eccentrically arranged piece of metal or another weight.

The rotatable in the housing 3 stored disc 1 always aligns with the gravitational field in one position. First, the housing 3 rotated, the angle of rotation can be read by the angle directly through the optics.

To protect against contamination should the disc 1 and the optical components 41 to 45 . 47 be housed in a tight housing. For this purpose, for example, by 2-component injection molding a seal directly into the housing halves 3 to get integrated.

In summary, therefore, to say that as a central element of the described invention preferably a transparent plastic disc 1 which is similar to a compact disc (CD) one-sided with a microstructure 11 . 12 and optionally with a metal coating 13 is provided. The disc 1 with the structuring 11 or 12 represents the material measure with respect to the angle of rotation. The plastic disc 1 and the structuring 11 or 12 are produced, for example, by micro injection molding or injection compression molding in one process step, whereby the structuring can already be carried out with the injection molding tool. Subsequently, the structured side can also be covered with a metal layer 13 be provided. The construction of the disc 1 thus resembles a conventional CD. In addition, by means of micro injection molding, further structural elements such as an axle or a gearing for use in a transmission can be used as integral elements directly with the disk 1 getting produced.

The Shaping the structuring by injection molding allows at low ratio the height to the width (aspect ratio) the high resolution of the micrometre and submicrometer range known from CDs. This allows the application of absolute angle marks on the smallest area possible. In this case, digital encodings can be produced. For example can for every measurable position stores 16bit information on a surface be whose length on the circumference, based on an angular resolution of 0.01 °, as it is required today for steering angle sensors, for example.

Claims (26)

Rotary encoder with the following features: an information carrier ( 1 ) containing a plurality of license plates ( 11 . 12 ), wherein a material of the information carrier ( 1 ) a material of a mark ( 11 . 12 ) and where a mark ( 11 . 12 ) is an optically detectable embodiment of an information from which a position of the information carrier ( 1 ) and an optical detector ( 4 ) for detecting the license plate ( 11 . 12 ), the information carrier ( 1 ) and the optical detector ( 4 ) are rotatably arranged relative to each other, and wherein a rotation angle of a relative rotation between the information carrier ( 1 ) and the detector ( 4 ) can be determined by a detection signal. Rotary encoder according to Claim 1, in which the information carrier ( 1 ) is a disk. Rotary encoder according to Claim 2, in which the disc ( 1 ) comprises an optically transparent plastic material. Rotary encoder according to one of Claims 1 to 3, in which the information carrier ( 1 ) comprises an information carrier surface, wherein a mark is a recess ( 11 ) in the information carrier surface. Rotary encoder according to one of Claims 1 to 4, in which the information carrier ( 1 ) comprises an information carrier surface, wherein a flag is a survey ( 12 ) from the information carrier surface. Rotary encoder according to one of Claims 4 or 5, in which the information carrier surface and the identifier ( 11 . 12 ) through a cover layer ( 13 ) are covered. Rotary encoder according to Claim 6, in which the covering layer ( 13 ) comprises a reflective material. Rotary encoder according to Claim 6, in which the information carrier ( 1 ) a material with a first optical refractive index (n _S ) and the cover layer ( 13 ) comprises a material having a second optical refractive index, wherein the first optical refractive index is different from the second optical refractive index. Rotary encoder according to claim 8 in which the first optical refractive index and the second optical refractive index Refractive index less than fifty Percent differ from each other. Rotary encoder according to a the claims 1 to 9, in which a license plate is a plurality of partial license plates includes. A rotary encoder according to claim 10, wherein the plurality of partial identifiers of the license plate ( 11 . 12 ), starting from a rotation axis ( 2 ) of the information carrier ( 1 ) on the same in Radialrich are arranged. Rotary encoder according to Claim 11, in which a first identifier ( 11 . 12 ) comprises a first number of sub-codes, and a second code ( 11 . 12 ) comprises a second number of sub-flags, wherein the first number of sub-flags corresponds to the second number of sub-flags. A rotary encoder according to claim 12, wherein a first sub-tag of the first tag has a higher significance than a second sub-tag of the first tag and a first sub-tag of the second tag has a higher significance than a second sub-tag of the second tag, the first sub-tag of the first tag and the first part mark of the second mark a substantially equal distance from the axis of rotation of the information carrier ( 1 ) and the second part identifier of the first identifier and the second part identifier of the second identifier a substantially equal distance from the axis of rotation of the information carrier ( 1 ) exhibit. A rotary encoder according to claim 13, wherein the first part identifier of the first number plate and the first part number plate of the second code number are represented by a recess (Fig. 11 ) or a survey ( 12 ) are interconnected. A rotary encoder according to any one of claims 11 to 14, wherein the information is a binary coded position information and a part identifier of a tag ( 11 . 12 ) corresponds to one bit of the binary coded position information. Rotary encoder according to Claim 15, in which the information carrier ( 1 ) a number of identifiers ( 11 . 12 ) corresponding to a maximum number of mutually distinguishable binary coded position information. Rotary encoder according to one of Claims 1 to 16, in which the optical detector ( 4 ) at least one light source ( 41 ) for outputting light of a predetermined wavelength (λ), a lens ( 42 . 44 ;) and a sensor element ( 45 ). A rotary encoder according to claim 17 when appended to claim 4, wherein the recess has a depth (d) having a predetermined relationship to the predetermined wavelength (λ) of the light of the light source ( 41 ) having. A rotary encoder according to claim 17 when appended to claim 5, wherein the elevation has a height (d) which is a predetermined relationship to the predetermined wavelength (λ) of the light of the light source ( 41 ) having. Rotary encoder according to one of Claims 17 to 19, in which the optical detector ( 4 ) is configured to detect an interference pattern and, based on the detected interference pattern, to be able to detect at least three different information values from the interference pattern on the basis of a first and a second threshold value. Rotary encoder according to one of claims 1 to 11, in which a tag comprises a first part identifier and a second part identifier, the first part identifier having information about an absolute position of the information carrier ( 1 ) and from the second part identifier information about an incremental change in position of the information carrier ( 1 ) can be determined. A rotary encoder according to claim 21, wherein the first sub-tag comprises binary-coded information formed on a substantially concentric first circle about an axis of rotation ( 2 ) of the information carrier ( 1 ) and the second sub-tag comprises a plurality of indistinguishable features disposed on a substantially concentric second circle about the axis of rotation (Fig. 2 ) of the information carrier ( 1 ) are arranged. Rotary encoder according to claim 22, in which the first part identifier and the second part identifier arranged such that a radial distance of the first circle is different from the radial distance of the second circle. Rotary encoder according to claim 23, in which the second part identifier has a greater length than the first one Partial tag. Rotary encoder according to one of Claims 1 to 24, in which the information carrier ( 1 ) an eccentric to a rotation axis ( 2 ) of the information carrier ( 1 ) arranged mass unit ( 5 ). Method for operating a rotary encoder, wherein the rotary encoder comprises an information carrier ( 1 ) containing a plurality of license plates ( 11 . 12 ), wherein a material of the information carrier ( 1 ) a material of a mark ( 11 . 12 ) and where a mark ( 11 . 12 ) is an optically detectable embodiment of information from which a position of the information carrier can be derived and an optical detector ( 4 ) for detecting the license plate ( 11 . 12 ), the information carrier ( 1 ) and the detector ( 4 ) are rotatably arranged relative to each other, and wherein a rotation angle of a relative rotation between the information carrier ( 1 ) and the detector ( 4 ) by a detek tion signal can be determined, with the following steps: turning the information carrier ( 1 ); and capturing a flag ( 11 . 12 ) with the optical detector ( 4 ).