Abstract:
Encoded scale bodies for position/displacement measuring systems and position/displacement measurement systems including scale bodies are disclosed. An encoded scale body includes a support band and at least one encoding layer made of encoding material. The encoding layer is arranged on the support band. The encoded scale body further includes a cover band which covers the encoding material towards an outside space. The cover band is formed by the support band. The support band/cover band is elastically flexible. The support band, which is the mechanical holder for the encoding material, may serve to mechanically stabilize the encoded scale body. The cover band covers the encoding material and may protect the encoding layer from external effects such as, in particular, mechanical forces. The flexible support band/cover band may permit the encoded scale body to be used as band material, and for example, a roll material.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present specification claims priority to German utility model application number 20 2009 003 253.1 filed Feb. 27, 2009, which is incorporated herein by reference. 
     TECHNICAL FIELD 
     This specification generally relates to an encoded scale body for a position/displacement measuring system, comprising a support band, at least one encoding layer made of encoding material, which is arranged on the support band, and a cover band which covers the encoding material towards an outside space. The invention further relates to a position/displacement measuring system. 
     BACKGROUND 
     Magnetically encoded scale bodies and position/displacement measuring systems which comprise such magnetically encoded scale bodies are described, for example, in the chapter “Wegsensoren mit magnetisch kodiertem Maβkörper” (Displacement Sensors with Magnetically Encoded Scale Body) in the publication “Lineare Weg-und Abstandssensoren” (Linear Displacement and Distance Sensors) by Thomas Burkhardt, Albert Feinäugle, Sorin Fericean and Alexander Forkl, Verlag Modeme Industrie, Munich 2004. Corresponding measuring systems comprise a sensor head, which contains magnetic field sensors and preferably the complete electronics, and a magnetically encoded scale body. The scale body comprises alternating magnetic north and south poles. The magnetic lines of field of the magnetically encoded scale body form a three-dimensional vector field. The sensor head moves above the scale body. The sensor head contains, for example, two magnetic field sensors which measure either the component of the magnetic field vector in the direction of their sensitivity or the angle of the magnetic vector field to the direction of motion. Counting magnetic periods provides information as to the distance traveled. 
     SUMMARY 
     In accordance with the invention, an encoded scale body is provided, which is simply constructed and comprises comprehensive application possibilities. 
     In accordance with an embodiment of the invention, in the encoded scale body the cover band is formed by the support band. 
     The support band is the mechanical holder for the encoding material and serves also to mechanically stabilize the overall arrangement. The cover band covers the encoding material towards the outside space and protects the at least one encoding layer from external effects such as, in particular, mechanical forces. 
     In the solution according to the invention, the support band and the cover band are one and the same, i.e., the support band has the protective function of the cover band. This results in a simple construction. 
     The support band and the at least one encoding layer lie directly on each other. Therefore, when there is any bending they do not move relative to each other. This, in turn, makes it possible to impart one or more bends to the encoded scale body (support band including encoding material) along the length direction and to variably adapt the encoded scale body to an application and to place it, in particular, at least partially thereon. This allows, for example, a correspondingly encoded scale body to be placed around a shaft or the like. 
     Furthermore, the correspondingly encoded scale body is simple to handle for the user. In particular, the encoded scale body can be provided as band material and, for example, as roll material. A user himself can then cut the length to the specific application. 
     In the solution according to the invention, the application can be used as “support” and “cover”, respectively; the at least one encoding layer can be applied to the application. 
     In particular, the cover band covers the encoding material towards a sensor device. The sensor device comprises one or more sensors which are sensitive to the encoding. This allows the at least one encoding layer to be protected towards the outside space. 
     In the case of a magnetically encoded scale body, the support band/cover band is produced from a non- or at the most slightly (in comparison with the encoding material) magnetizable material. It is produced, for example, from a metallic material and, in particular, stainless steel. It is thereby dimensionally stable and elastic in order to provide a high variability and adaptability, in particular, owing to its elastic flexibility. Furthermore, a plastic deformation is also possible, for example, to produce hook elements, as described in greater detail below. 
     In the case of a capacitively encoded scale body, the support band/cover band is preferably made of an electrically non-conductive material. In the case of an optically encoded scale body, the support band/cover band is transparent in the relevant spectral range. 
     In a scale body which is mounted on a component the at least one encoding layer made of encoding material preferably lies between the component and the support band/cover band. This protects the layer of encoding material towards the outside space and towards the application by abutment on the application. Furthermore, this enables simple and secure fixing to the application. If the application itself consists of a magnetizable material, the encoding layer can also be fixed to the application by means of magnetic adherence if the encoding layer is produced from a magnetic material. 
     It can be provided that the at least one encoding layer contacts the component at least partially. This provides support for the encoded scale body on the application. 
     In particular, the encoding material is fixed directly to the support band/cover band and, for example, adhesively bonded to it. This results in a simple construction. 
     It is advantageous if the support band/cover band is dimensionally stable. This results in optimal adaptability to an application. 
     It is furthermore favorable if the support band/cover band is elastically flexible. This makes it possible, for example, to provide the encoded scale body as band material, for example, in the form of a roll. The elastic flexibility enables optimal adaptability to an application. 
     It is quite particularly advantageous if the support band/cover band with the encoding material arranged thereon is flexible, i.e., the encoded scale body is flexible and, in particular, elastically flexible, as a whole. 
     It is advantageous if the scale body consists, with respect to the sequence of layers, of the support band/cover band and the at least one encoding layer on the support band/cover band. The at least one encoding layer is, in particular, fixed with a substance-to-substance connection (for example, using a layer of adhesive) to the support band/cover band. 
     The encoded scale body comprises a first surface which is formed on the encoding material and an opposing second surface which is formed on the support band/cover band. This first surface and the second surface are outer surfaces. 
     It can be provided that the scale body has a bend. The bend can be produced by plastic deformation or elastic deformation using appropriate force. 
     In one embodiment, the support band/cover band has a curve or bend at at least one end. This curve or bend creates a type of hook element for hooking the scale body to a corresponding opening. This makes it possible, for example, to produce a closed device which includes the encoded scale body. Encoding material may or may not be arranged at the curve or bend. 
     It is advantageous if a connecting device is provided which connects a first area of the scale body and a second area of the scale body to each other, the first area lying in the vicinity of a first end of the scale body and the second area in the vicinity of a second end of the scale body. This allows the encoded scale body to be placed around an application and, in particular, this application can be enclosed. The connecting device ensures that the previously free ends are coupled to each other. This enables fixing to the application. 
     In one embodiment, the connecting device comprises a first fixing device for a first area of the scale body and a second fixing device for a second area of the scale body, a distance between the first fixing device and the second fixing device being fixedly adjustable. This enables the scale body to be placed around an application and allows it to have close contact with the application over an entire measuring range. The first fixing device and the second fixing device are, for example, openings through which hook elements of the scale body produced by bends or curves are looped. 
     In particular, the combination of scale body and connecting device forms a closed device. The closed device allows an application such as, for example, a shaft to be enclosed in order to fix the encoded scale body to this application. 
     In one embodiment, the scale body is magnetically encoded. The encoding material is then a magnetic material. The encoding is formed by a particular sequence of north and south pole fields. 
     It can also be provided that the scale body is affixed to a magnetizable component by magnetic adherence. In addition, a further mechanical fixing can be provided, for example, using a connecting device. The fact that the magnetic material can be positioned facing an application and can contact it enables such a fixing by magnetic adherence. 
     In principle, it is also possible for the scale body to be capacitively encoded. In such an “electrostatic” encoding, capacitive-sensitive sensors can be used to read an encoding. The support band/cover band is then produced from an electrically non-conductive material. 
     It is also possible to optically encode the scale body. One or more corresponding optical sensors can then read the encoding. 
     In this case, the support band/cover band is transparent in the relevant spectral range. 
     It is advantageous if the at least one encoding layer is in the form of a band. This allows the scale body to be produced simply by joining a first band, namely the at least one encoding layer, to a second band, namely the support band/cover band. 
     It is quite particularly advantageous if the encoded scale body is formed in its entirety as a band. This allows a user to easily adapt the scale body to a special application. In particular, it is easy to make shape and length adjustments. For example, the scale body is then provided as a roll and a user can carry out the appropriate cutting to length. 
     Furthermore, in accordance with the invention, a position/displacement measuring system is provided, which comprises at least one scale body according to the invention and a sensor device comprising at least one sensor which is sensitive to the encoding. 
     In particular, the sensor device is positioned facing the cover band, so that the cover band covers the encoding material towards the outside space. 
     In one embodiment, the at least one sensor is sensitive to magnetic fields and the scale body is magnetically encoded by a particular sequence of magnetic north and south poles. 
     The following description serves in conjunction with the drawings to explain the invention in greater detail. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a schematic representation of an embodiment of a position/displacement measuring system according to the invention; 
         FIG. 2  shows a further representation of a section of a magnetically encoded scale body of a position/displacement measuring system according to the invention; 
         FIG. 3  shows an embodiment of a connecting device; and 
         FIG. 4  shows an embodiment of a position/displacement measuring system according to the invention, which is arranged on an application. 
     
    
    
     DETAILED DESCRIPTION 
     An embodiment of a position/displacement measuring system according to the invention, which is shown schematically in  FIG. 1  and indicated there by  10 , comprises a magnetically encoded scale body  12  and a sensor device  14 . The scale body  12  can be affixed to an application  16 . The sensor device  14  comprises at least one magnetic-field-sensitive sensor and, in particular, a plurality of magnetic-field-sensitive sensors. 
     Position/displacement measuring systems with a magnetically encoded scale body are described, for example, in the chapter “Wegsensoren mit magnetisch kodiertem Maβkörper” (Displacement Sensors with Magnetically Encoded Scale Body) in the publication “Lineare Weg-und Abstandssensoren” (Linear Displacement and Distance Sensors) by Thomas Burkhardt, Albert Feinäugle, Sorin Fericean and Alexander Forkl, Verlag Moderne Industrie, Munich 2004. Explicit reference is made to this publication. 
     The scale body  12  comprises a support band  18  which is made of a non-magnetizable material. The support band  18  is made, in particular, of a metallic material and, for example, of stainless steel. 
     Arranged on the support band  18  is a device  20  made of magnetic (magnetizable) material as encoding material. This device  20  comprises at least one encoding layer  22  with magnetic pole fields  24 . In the embodiment shown, the device  20  made of magnetic material comprises a first encoding layer and a second encoding layer. 
     In one encoding layer  22  magnetic pole fields (north pole fields and south pole fields) alternate with each other, the size and/or sequence of the pole fields determining the encoding. The encoding determines the field exposure of the sensor device  14  and is location-dependent. The position of the sensor device  14  relative to the scale body  12  can thereby be determined (without contact) by processing the corresponding signal. 
     The magnetic lines of field of the at least one encoding layer  22  form a three-dimensional vector field. The sensor device  14  is positioned in this vector field. For example, the sensor device  14  moves in the vector field. By counting magnetic periods which are detected by the sensor device  14 , information on the distance traveled is obtained, and a directionality can be detected by a corresponding alignment of the sensor device  14 . Absolute positions can, for example, be determined by carrying out a reference run. 
     It is also possible to implement the position/displacement measuring system  10  as an absolute measuring system without the need for a prior reference run. For this purpose, the at least one encoding layer  22  comprises in addition to at least one incremental track an absolute track which can be sensed by corresponding and magnetic-field-sensitive sensors of the sensor device  14 . Reference is made here to the above-mentioned publication. 
     The device  20  is affixed to the support band  18  and, in particular, adhesively connected to it. The support band  18  is the (mechanical) holder for the device  20  made of magnetic material. 
     In one embodiment, the device  20  with the at least one encoding layer  22  is itself a band (indicated in  FIG. 1  by reference numeral  24 ) which is affixed to the support band  18 . 
     The magnetically encoded scale body  12  consists of the support band  18  and the device  20 . The support band  18  forms a cover band  26  which covers the device  20  made of magnetic material and, in particular, protects it from mechanical damage. 
     The support band/cover band  18 ,  26  covers the device  20  made of magnetic material, in particular, towards an outside space. The cover band  26  is, in particular, arranged between the device  20  and the sensor device  14 . 
     When positioning the scale body  12  on an application it is provided that the device  20  made of magnetic material faces the application  16  and, for example, rests against it. If the application  16  is made of a magnetizable material, then the magnetic forces of the device  20  can cause the scale body  12  to adhere to this application  16 . 
     The magnetically encoded scale body  12  consists, with respect to the sequence of its layers, of layers of the support band  18 /cover band  26  and the affixed (in particular, adhesively) device  20  made of magnetic material, and, as indicated above, the device  20  can comprise one or more encoding layers  22 . The scale body  12  has a first surface  28  which is formed on the magnetic material of the device  20 , and an opposing second surface  30  which is formed on the support band  18 /cover band  26 . The first surface  28  and the second surface  30  are preferably arranged at least approximately parallel to each other. The second surface  30  faces the sensor device  14  and the first surface  28  faces the application  16  and contacts the latter, for example, at least partially. 
     The scale body  12  with the support band  18  and the device  20  is, in particular, itself band-shaped and dimensionally stable. It is flexible and, in particular, elastically flexible as a whole in relation to a longitudinal direction of extent  32 . This makes it possible to impart a bend to the scale body  12  and attach it, for example, to an uneven surface of an application  16 . For example, it is possible to attach the scale body  12  to a cylindrical application. 
     The scale body  12  as a whole including support band  18 /cover band  26  and device  20  is flexible so that the device  20  with the at least one encoding layer  22  can also be adapted in its form. 
     The band-shaped scale body  12  has a first end  34  and a second end  36  ( FIG. 2 ). It is thereby, in principle, possible for the device  20  made of magnetic material to extend to the first end  34  and/or the second end  36 , i.e., to the corresponding end of the support band  18 , or for a corresponding first end and second end of the device  20  made of magnetic material to lie in front of the corresponding end of the support band  18 . The ends of the scale body  12  are thereby formed by the ends of the support band  18 . 
     In one embodiment, a closed device  38  is formed by the scale body  12  which encloses an interior space  40  and thereby can be placed around an application  42  ( FIG. 4 ). The closed device  38  is of one-piece coherent configuration in a geometrical sense. 
     The closed device  38  can be produced by a connecting device  44  ( FIGS. 2 ,  3 ) by means of which a first area  46  can be connected to or near the first end  34  and a second area  48  to or near the second end  36 . 
     The scale body  12  comprises by virtue of the support band  18  (with or without device  20  made of magnetic material in the corresponding area) at the first area  46  and the second area  48 , respectively, a bend or curve  50 . This bend or curve  50  is formed by plastic deformation of the support band  18  (which may follow the device  20 ). 
     The connecting device  44  comprises as first fixing device a first opening  52  through which the scale body  12  is passed at the first area  46  with the corresponding bend or curve  50 . Furthermore, the connecting device  44  comprises as second fixing device a second opening  54  through which the scale body  12  is passed in the second area  48  with the corresponding bend or curve  50 . The scale body  12  is held in hook fashion on the connecting device  44  by means of the bend or curve  50 . 
     The distance between the first opening  52  and the second opening  54  is adjustable. For example, by shortening the distance between the first opening  52  and the second opening  54  a better abutment of the scale body  12  on the application  42  can be achieved, i.e., the application  42  can be positioned in the interior space  40 , and by reducing the distance between the first opening  52  and the second opening  54  it is affixed to the application  42 . 
     In  FIG. 3 , the relative adjustability of the distance between the first opening  52  and the second opening  54  is indicated by the double arrow with reference numeral  56 . 
     A locking device  58  can be provided to adjust and fix a position. The connecting device  44  comprises, for example, a web element  60  with discretely spaced openings  62 . At the web element  60  near a first end  63  the first opening  52  is formed. 
     The connecting device  44  furthermore comprises the locking device  58  on which the web element  60  is mounted in a fixedly displaceable manner. The second opening  54  is located on the locking device  58 . By adjusting the displacement position relative to the web element  60  of the locking device  58  the distance between the first opening  52  and the second opening  54  can be set and fixed using the locking device  58 . For this purpose, for example, there is located on the locking device  58  a screw which can extend into a corresponding opening  62 . The special opening  62  determines the distance. 
     A tension force may also be exerted using the locking device  58  so that the closed device  38  can be held tightly against the application  42 . 
     The connecting device  44  is formed, for example, in the manner of a clamp. 
     An application example is shown in  FIG. 4 . The corresponding position/displacement measuring system  10  is positioned on a cylindrical application  42 . The scale body  12  is placed circumferentially around the application  42 , and the closed device  38  is produced using the corresponding connecting device  44 . The sensor device  14  is spaced from the scale body  12 . The latter is covered and thereby protected towards the outside space by the cover band  26 . 
     This makes it possible, for example, to detect angular positions of the application  42  relative to the sensor device  14 . For example, the application  42  with the affixed scale body  12  can be rotated (in particular, the application  42  is a shaft) or pivoted relative to the fixed sensor device  14 . This is indicated in  FIG. 4  by the double arrow  64 . 
     It is, for example, also possible that the application  42  is stationary with the scale body  12  immovably mounted on it and that the sensor device  14  is positionable in various angular positions relative to the application  42 . For example, the sensor device  14  is movable on an orbital path. The corresponding position can be detected on this path. 
     It is, in principle, also possible that both the position of the application  42  with the scale body  12  and the position of the sensor device  14  can be altered. 
     In the solution according to the invention, the cover band  26  is identical with the support band  18 . The cover band  26  has both the mechanical support function for the device  20  made of magnetic material and a protective function with respect to external effects for the device  20 . In the application case according to  FIG. 4 , the cover band  26  protects, for example, against radial effects such as mechanical forces. 
     The scale body  12  can be simply formed in an elastic manner so that it can also be affixed to curved surfaces. By means of the integral formation of support band  18  and cover band  26  a bending of the scale body  12  as a whole is simple to perform without the risk of separating the device  20  from the support band  18 . In a construction consisting of the sequence support band, device made of magnetic material, cover band there is an inherent risk of separation, since the support band and the cover band impinge on the device differently from two sides when there is a bend. The solution according to the invention eliminates this risk. 
     By providing the connecting device  44  it is simple to place the scale body  12  circumferentially around an application. The application can then have basically any shape. 
     The scale body  12  can be affixed to a surface of a magnetizable application by means of the corresponding magnetic forces, and the exact position can be easily adjusted. This results in simplified installation when the application is magnetizable. 
     The scale body  12  is dimensionally stable in its longitudinal direction of extent  32  with integrated protection provided by the cover band  26 . 
     In principle, the scale body  12  can be supplied as band material so that a user can also easily shorten the scale body  12  to suit the application and affix it using the connecting device  44 . 
     In accordance with the invention, a flexible and at the same time economical solution is provided. 
     With use of the position/displacement measuring system  10  according to the invention, measuring accuracies on the order of ±20 μm or better can be achieved when the magnetic encoding is correspondingly implemented in the at least one encoding layer  22 . 
     In the solution according to the invention, the application  16 ,  42  is also used as contact surface. 
     The idea according to the invention can also be applied to encoded scale bodies which are not magnetically encoded. For example, corresponding capacitively encoded scale bodies can be provided. In this case, the support band/cover band is made of an electrically non-conductive material. The at least one sensor of a corresponding position/displacement measuring system is then sensitive to electrostatic fields. 
     In another embodiment, the scale body is optically encoded. The support band/cover band is then optically transparent in the relevant spectral range. The corresponding sensor device of the thereby formed position/displacement measuring system comprises at least one optical sensor which can detect the encoding.