Method for forming scale body on guide rail surface of linear profile rail guide, scale body for linear encoder, and linear encoder

Abstract

To provide an optimized method for forming a scale body on a guide rail surface of a linear profile rail guide.SOLUTION: A guide rail 2 has a first side surface 2.1 and an opposite second side surface 2.2. A scale body 5 includes at least one of linear tracks SP1, SP2 extending in a longitudinal direction X of the guide rail 2, which have a mirror area and a marking area arranged back and forth by turns. The method has: a method step of providing a pulsed laser for forming a laser beam; and a method step of providing at least one marking area of a plurality of marking areas M1, M2, M3, M4, M5, M6, M7, M8, M9, M10, M11, M12, M13, M14 by forming a refined pattern within a first area B1 equivalent to at least one marking area on the first side surface 2.1 of the guide rail 2.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates generally to a scale body for a linear encoder and an optimized method for forming the scale body onto a surface of a guide rail of a linear profile rail guide. [Background technology]

[0002] Scale bodies are basically known from the prior art. They are used in particular in incremental encoders, which are sensors for detecting (linear) position changes or (rotational) angular changes, which can detect distance and direction or angular changes and direction of rotation. Known scale bodies for incremental encoders have periodically repeating scattering areas or multiple absorbing areas which are counted by a sensor device to detect the position change.

[0003] Thus, for example, from the publication DE 25 15 574 A1, a metallic scale body is known which has a scattering region consisting of a number of linear elements which are parallel and narrow, the width and depth of which are designed such that the linear elements of the scattering region are not individually distinguishable with visible light, but are detectable only by the diffraction image of these linear elements.

[0004] In other words, each scattering region known from DE 2515574 consists of a number of linear recesses (linear elements) arranged directly next to each other, having a width of the order of 1 μm (in particular 0.5 to 1.5 μm) and a depth of approximately 1.5 μm and thus in the order of the wavelength of light (the known scale body is illuminated by light in an illumination mode, for example under a photoelectron microscope).

[0005] In an illumination method, as can be seen for example from publication DE 102007007311, a light beam is deflected by a collimator onto a surface with a reflective scale body. As a result, the surface or the scale body is illuminated with approximately parallel focused light, which is incident at an angle to the surface normal. In this case, the scale body comprises a number of patterned areas that are patterned in a line grid with a diffractive phase grating pattern and a number of non-patterned areas that are each formed by a smooth (mirror) surface.

[0006] In this case, the angle of incidence of the light incident on the surface is selected such that the light is diffracted at the diffractive phase grating pattern in the patterned area, and the diffracted light of the first diffraction order leaves the scale body perpendicularly. In this situation, the light incident on the non-patterned areas, hereinafter referred to as "mirror areas", is reflected by the surface, so that the light leaves the non-patterned areas at an exit angle equal to the angle of incidence with respect to the surface normal. The light diffracted by the patterned areas approximately perpendicular to the surface is then imaged onto a number of light sensors of the sensor device. In this case, the sensor device is advantageously arranged such that the light reflected by the non-patterned areas (mirror areas) is not detected by the light sensors of the sensor device.

[0007] Thus, using the sensor device, the patterned areas are detectable as bright fields and the non-patterned areas (mirror areas) are detectable as dark areas.

[0008] When the sensor device is moved along the incremental track, it detects light diffracted in particular in the patterned areas (dark area measurement in the patterned areas). The patterned areas and the non-patterned areas (mirror areas) are respectively arranged one after the other in alternating rows and together form a common incremental track. In this case, several patterned areas are arranged at regular intervals and are separated from one another by several mirror areas. Each of these patterned areas thus forms a so-called marking area. In this case, when the sensor device is moved in the longitudinal direction of the incremental track relative to the marking area, the respective marking areas of this incremental track can be counted by the sensor device and converted into a periodically changing sensor signal.

[0009] The periodic sensor signal can be used by the calculation unit to calculate the displacement along the scale body. Since the sensor signal changes periodically during the longitudinal displacement of the incremental track of the sensor arrangement, it is possible to measure the respective sensor signal at different positions of the sensor arrangement during the longitudinal displacement of the incremental track of the sensor arrangement and to assign different measurement values ​​for the sensor signal to different positions of the sensor arrangement. Finally, by interpolating between the different measurement values ​​for the sensor signal that are assigned to different predefined positions of the sensor arrangement relative to the incremental track, any position of the sensor arrangement (between two predefined positions of the sensor arrangement) can be calculated with high precision.

[0010] To increase the sensor signal, it is possible to simultaneously illuminate the scale body with light from two different light sources arranged side by side, so that light is incident on the surface or scale body from two different directions (each at an angle to the surface normal).

[0011] The scale bodies known from the prior art have the disadvantage that the sensor signals detected by the sensor device often only have a low contrast, i.e. the sensor devices generate sensor signals by scanning the scattering or absorbing regions and the mirror regions, respectively, only to the extent that the sensor signals generated by scanning the scattering or absorbing regions and the mirror regions differ relatively little and therefore only have a relatively small difference (contrast).

[0012] As a result, the individual scattering or absorbing regions are not properly identified and the amount of movement of the sensor device relative to the scale body is not accurately detected. Furthermore, it has been recognized that with the scale bodies known from the prior art, it is very difficult to interpolate the sensor signal obtained by reflection on the scale body.

[0013] On the other hand, there is a need, in particular, to provide a displacement measuring system that operates according to the principle of bright field measurement, where the position change can be reliably detected by a detector arranged in the "bright field". Bright field measurement means that the beam reflected from the mirror area reaches the detector directly when no scattering or absorbing areas of the scale body are present in the measurement area of ​​the displacement measuring system.

[0014] This means in particular that the light source illuminates the scale mounted on the scale body parallel to the beam path of the sensor. This differs from dark field illumination, in which the scale is illuminated at an angle of, for example, 45°. In this case, the functional mechanism of the used encoder of a displacement measuring system operating according to the bright field measurement principle requires that the light emitted by the light source is reflected regularly (mirror-like) at the mirror areas of the scale body. If possible, it is desirable for each beam incident on the surface of the scale body to be reflected in the respective mirror area of ​​this scale body at the same angle to the surface normal.

[0015] Generally, a linear profile rail guide comprises a (linear) guide rail and at least one mobile body, which is guided in the guide rail such that it is movable in the longitudinal direction of the guide rail. In the case of such a profile rail guide, it is generally required to determine, in metrological terms, the position of the mobile body, which is guided in the guide rail and which is linearly movable in the longitudinal direction of the guide rail.

[0016] In this case, for metrological detection of the position of the movable body, a linear encoder can be used which comprises a scale body extending in the longitudinal direction of the guide rail and a sensor device movable in the longitudinal direction of the guide rail relative to the scale body in order to scan the respective marking area of ​​the scale body. To enable metrological detection of the position of the movable body of the linear profile rail guide, the sensor device can be arranged on the movable body such that the sensor device is movable together with the movable body in the longitudinal direction of the guide rail.

[0017] In order to enable a simplified installation of a linear profile rail guide combined with a linear encoder for metrologically detecting the position of a movable body movable in the longitudinal direction of the guide rail of the linear profile rail guide, it has been proposed in particular to provide the guide rail of the linear profile rail guide together with the scale body as a single workpiece, for which purpose the respective marking areas of the scale body are formed by a surface processing process of the guide rail, for example by a surface processing process using a laser beam.

[0018] From EP 3060887, a scale body for an incremental encoder and a method for producing the scale body on a metal surface by means of a pulsed laser are known. In this case, the method is basically suitable for realizing a corresponding scale body on the surface of a guide rail of a linear profile rail guide. The method disclosed in the publication EP 3060887 is designed for an incremental encoder with a scale body with an incremental track having a number of scattering regions and a number of absorbing regions arranged alternately in the longitudinal direction. In this case, the incremental encoder comprises a sensor device. The sensor device comprises a measuring head which is arranged for optical scanning of the incremental track and for this purpose is movable relative to the scale body and has an optical imaging device for generating an image of the incremental track and a number of light sensors for detecting said image. To enable optical scanning of the incremental track, it is proposed to illuminate the incremental track by two light sources. The two light sources generate light which is incident at an angle on the scattering and absorbing regions of the scale body. This angle is selected so that light reflected directly from the mirror areas of the scale body does not strike the optical imaging device and therefore cannot be detected by the optical sensor. Instead, the sensor device is configured to detect only light scattered in the scattering areas of the scale body in a direction approximately perpendicular to the metal surface on which the scale body is formed (this corresponds to optical detection of the scattering areas of the scale body according to the principle of dark area measurement). In order to achieve that the scattering areas of the scale body are detected by the sensor device with as large a contrast as possible compared to the mirror areas, the publication EP 3060887 proposes to produce the scattering areas of the scale body on the metal surface by treating the surface with a pulsed laser so that each of the scattering areas has at least two linear recesses.At least two linear recesses extend substantially perpendicular to the longitudinal direction of the incremental track, are arranged in a row one behind the other in the longitudinal direction of the incremental track, and are formed to diffusely reflect incident light, with each of the linear recesses of the scattering region being formed from a plurality of approximately circular recesses arranged one above the other. The publication EP 3060887 proposes that, with respect to the dimensions of the linear recesses of a scattering region, which is an array of linear recesses of the scattering region, the width of the linear recesses in the longitudinal direction of the incremental track and / or the respective spacing between two adjacent linear recesses can be appropriately selected so that the spatial intensity distribution of the light scattered and reflected from the linear recesses of each scattering region can be made relatively uniform, and that when each linear recess has a width of 3.5 μm to 12 μm, preferably 6 μm to 9 μm and in particular approximately 7 μm, in the longitudinal direction of the incremental track and the spacing between two adjacent parallel linear recesses is greater than zero, the scattering region of the scale body can be detected by the sensor device with a relatively large contrast compared to the mirror region during optical detection of the scattering region of the scale body according to the principle of dark area measurement realized in this case. In this regard, EP 3060887 proposes, inter alia, that the scattering regions each have at least three parallel linear recesses oriented perpendicular to the longitudinal direction of the incremental track and spaced apart from one another by an interval of 6 to 9 μm, preferably about 7.5 μm.

[0019] The scale body known from the publication EP 3060887 has been found to be problematic during optical scanning of the scale body according to the principle of bright-field measurement, where the light incident on the scale body is reflected by the mirror areas and scattered by the individual scattering areas (each formed by a number of linear and spaced-apart recesses) in such a way that during optical detection of the scattering areas of the scale body according to the principle of bright-field measurement, the scattering areas of the scale body can in any case only be detected by the sensor device with a lower contrast than the mirror areas. This makes it difficult to evaluate the measurement signal generated by the sensor device and significantly reduces the measurement accuracy of the longitudinal displacement of the scale body detected by the sensor device when the sensor device is moved in the longitudinal direction of the scale body.

[0020] Therefore, the profile rail guides known from the prior art with the scale body known from the publication EP 3 060 887 are hardly suitable for optically scanning the scale body according to the bright field measurement principle. [Prior art documents] [Patent documents]

[0021] [Patent Document 1] German Patent No. 2515574 [Patent Document 2] German Patent No. 102007007311 [Patent Document 3] European Patent No. 3060887 Summary of the Invention [Problem to be solved by the invention]

[0022] It is therefore an object of the present invention to provide an optimized method for forming a scale body on the surface of a guide rail of a linear profile rail guide, the scale body being suitable for use as a component of a linear encoder which is designed to reliably enable detection of position changes based on optical scanning of the scale body according to the bright field measurement principle.

[0023] It would further be desirable to provide a corresponding scale body and a corresponding linear encoder. [Means for solving the problem]

[0024] The problem relating to the inventive method is solved by the method according to independent claim 1. The problem relating to the inventive scale body is solved by a scale body according to claim 10, and the problem relating to the inventive linear encoder is solved by a linear encoder according to claim 13.

[0025] The method is used to form a scale body on a surface of a guide rail of a linear profile rail guide, where the guide rail has a first side and an opposing second side; the scale body includes at least one linear track extending in a longitudinal direction of the guide rail, the linear track having a plurality of mirror areas and a plurality of marking areas arranged one behind the other; Each of the plurality of marking regions extends linearly transversely (perpendicularly) to the longitudinal direction of the at least one track; The method comprises: providing a pulsed laser for forming a laser beam; providing at least one of the plurality of marking areas by forming a micropattern in a first area of ​​the guide rail corresponding to at least one marking area of ​​the first side, the method comprising: a laser forms a laser beam having a series of multiple light pulses, the laser beam being directed toward a first region of the first side; the first side surface is illuminated in only one sub-region of the first region by each individual light pulse of the formed succession of light pulses, and the first side surface is altered in the sub-region of the first region illuminated by each individual light pulse such that, due to illumination by the respective individual light pulse, the first side surface has a spatial modulation of the first side surface that extends over the sub-region of the first region illuminated by the respective individual light pulse after illumination by the respective individual light pulse; a spatial dimension of a partial area illuminated by each individual light pulse of the first area in the longitudinal direction of the at least one track is smaller than a spatial dimension of the first area in the longitudinal direction of the at least one track, and a spatial dimension of a partial area illuminated by each individual light pulse transversely to the longitudinal direction of the at least one track is smaller than a spatial dimension of the first area transversely to the longitudinal direction of the at least one track, The laser beam is moved relative to the guide rail such that at least a few of the successive light pulses formed irradiate a plurality of different partial regions of the first region, which are spatially distributed with respect to one another, in succession in time.

[0026] In this case, for each individual one of the illuminated different partial areas there is at least one further one of the illuminated different partial areas which is offset relative to the respective individual one of the illuminated different partial areas in the longitudinal direction of the at least one track and / or transversely to the longitudinal direction of the at least one track, so that the respective individual one of the illuminated different partial areas and the at least one further one of the illuminated different partial areas have an overlapping portion, in which the illuminated different partial areas together form a first lateral area that is congruent to the first area.

[0027] In particular, for each individual partial area of ​​the illuminated multiple different partial areas there are at least two further partial areas of the illuminated multiple different partial areas, which are spatially offset with respect to each individual partial area of ​​the illuminated multiple different partial areas in such a way that one of the at least two further partial areas of the illuminated multiple different partial areas is offset in the longitudinal direction of at least one track with respect to each individual partial area of ​​the illuminated multiple different partial areas, so that one of the at least two further partial areas of the illuminated multiple different partial areas is offset in the longitudinal direction of at least one track with respect to each individual partial area of ​​the illuminated multiple different partial areas. and each individual partial area of ​​the illuminated plurality of different partial areas have an overlapping portion (in the longitudinal direction of at least one track), and another partial area of ​​the at least two other partial areas of the illuminated plurality of different partial areas is shifted laterally with respect to the longitudinal direction of at least one track with respect to each individual partial area of ​​the illuminated plurality of different partial areas, so that the other partial area of ​​the at least two other partial areas of the illuminated plurality of different partial areas and each individual partial area of ​​the illuminated plurality of different partial areas have an overlapping portion (in the longitudinal direction of at least one track).

[0028] In the method of the invention, a laser beam is moved in two dimensions over the marking area of ​​a first region of a first side of the guide rail, which corresponds to the scale body to be formed. As a result, a number of different partial regions of the first region of the first side are successively irradiated. The irradiation of a partial region with one of a number of light pulses causes a slight removal and / or spatial redistribution of the material forming the first side of the guide rail. As a result, the shape of the surface of the irradiated partial region changes after irradiation with the light pulse.

[0029] In this context, "subregions of the first region illuminated by respective individual light pulses" refers to subregions of the first side whose surface shape in the illuminated subregions has changed due to illumination by respective individual light pulses (compared to the spatial modulation of the surface prior to illumination by the respective individual light pulses). It should be noted that the spatial dimension of the subregions whose surface shape in the illuminated subregions of the first side has changed due to illumination by respective individual light pulses may depend on the intensity of the respective light pulses.

[0030] The laser beam is moved across a first region of a first side of the guide rail such that each of the irradiated different partial regions overlaps at least one other partial region of the irradiated partial region, such that the first side of the guide rail is spatially modulated within the first region after irradiation with the light pulse. As a result, the roughness of the first side in the first region is increased - compared to the state of the first region before irradiation with the light pulse. Irradiation of the first region with the light pulse allows the first side to be micropatterned such that the smooth surface before irradiation has an array of multiple raised portions that exhibit a substantially uniform surface roughness over the entire first region after irradiation ("micropatterned").

[0031] The roughness of the surface changes the reflectivity of the surface in the illuminated first region such that light incident at a direction normal to the surface is not reflected back at the illuminated first region of the surface normal to the surface, but is instead multiply scattered and absorbed between individual raised portions formed within the illuminated first region.

[0032] The partial regions of the first region, each illuminated by an individual light pulse, are spatially distributed such that each illuminated partial region illuminated by an individual light pulse overlaps with at least two other partial regions illuminated by an individual light pulse. The respective partial regions are spatially shifted relative to one another such that each illuminated partial region illuminated by an individual light pulse overlaps with one other partial region that is shifted in the longitudinal direction of at least one track and further with one other partial region that is shifted transversely to the longitudinal direction of at least one track. Thus, the partial regions of the first region, each illuminated by an individual light pulse, overlap in two dimensions (i.e. in the longitudinal direction of at least one track and transversely to the longitudinal direction of at least one track). Due to the two-dimensional overlap, the reflectivity of the surface in the illuminated first region is very strongly reduced.

[0033] A scale body manufactured by the method of the invention therefore has the advantage that the marking areas of the scale body substantially absorb light incident perpendicularly to the surface, in which case the sensor device of the linear encoder provided for optical scanning can in this situation essentially only detect light reflected at the mirror areas.

[0034] The marking area of ​​the scale body can therefore be advantageously detected by the sensor arrangement with a relatively large contrast compared to the mirror area upon optical scanning of the marking area according to the bright field measurement principle.

[0035] Therefore, according to the invention, in particular, a fine pattern is formed by a pulsed laser in the respective marking areas of the scale body on the first side of the guide rail such that a dark, high-contrast surface is formed without removing material. Extremely short light pulses form a pattern with a large number of raised portions in the nanometer range on the surface of the guide rail. In the finely patterned surface, light scattering is reduced and the surface blackness (Schwaertzburg) is persistently deep, black and stable in the respective marking areas of the scale body.

[0036] In other words, according to the invention, the highly reflective metal surface of the guide rail is partially roughened by a high-energy beam (laser beam) in order to form an absorbing region in the metal surface. In this case, more specifically, the metal surface is melted with the high-energy laser beam by short laser pulses. In particular, the roughened regions are melted by short laser pulses of duration less than 15 nanoseconds. This allows the surface to instantly resolidify during the pulse pauses.

[0037] If the light pulses used to form the fine patterns in the marking areas are ultrashort (having a pulse duration of less than 20 picoseconds), the color change within a certain parameter range remains corrosion-resistant. This is because, by using an ultrashort pulse laser, the thermal action zone is extremely narrow, and as a result, a self-healing oxide film can form in the rough areas.

[0038] The advantage of the method of the invention for forming the scale body on the surface of the guide rail is in particular that the formed micropattern has so-called field-angle stability: the very high and uniform contrast from all field angles is due to the nanopattern formed when forming the micropattern on the first side of the guide rail, which repeatedly scatters and reflects light and absorbs it.

[0039] Furthermore, when using an ultrashort pulse laser, a very small and fine roughened area can be formed on the first side surface. When using an ultrashort pulse laser, the pulse duration is about 10,000 times shorter and therefore more energetic than with other marking lasers, and the roughened area can be applied with a very small spot size. Therefore, the method of the present invention is particularly suitable for forming a fine roughened area on the first side surface of the guide rail, and in particular for forming a fine absorbing area on the first side surface of the guide rail.

[0040] The short duration of action when using an ultrashort pulse laser ensures the chemical stability of the surface, which allows the formation of corrosion resistance in the roughened areas and therefore in the marking areas of the scale body.

[0041] Thus, according to a preferred configuration of the method of the invention, in particular the laser is configured as a short pulse laser for forming a pulsed light beam with a plurality of light pulses having a pulse duration of less than 15 nanoseconds or as an ultrashort pulse laser for forming a pulsed light beam with a plurality of light pulses having a pulse duration of less than 20 picoseconds. The pulse parameters of the laser and / or the laser focus are selected such that when the micropattern is formed on the first side of the guide rail without removing or substantially without removing material along the surface path, a material roughness in the nanometer range is formed.

[0042] The use of an ultrashort pulsed laser allows the side of the guide rail to be processed almost without thermal and mechanical effects. The duration of the light pulse, i.e. the energy input, is so short that even heat transfer to adjacent atoms does not occur, and thus thermal load cracks, which may occur when selecting inappropriate parameters, are also avoided. For this reason, forming a fine pattern on the first side of the guide rail by means of an ultrashort pulsed laser, can also be called "cold processing". In this cold processing, the material is patterned by the laser in the nanometer range.

[0043] The laser beam may provide an approximately circular beam bundle with a diameter selected, for example, such that the laser beam has a diameter of 3.5 μm to 12 μm, preferably 6 μm to 9 μm, in particular about 8 μm, at the first side of the guide rail.

[0044] To form a micropattern in a first region of the first side of the guide rail corresponding to the marking region, a laser beam can be directed to the first region of the first side such that an overlap between each individual one of the irradiated different partial regions and at least one other one of the irradiated different partial regions has a spatial dimension in the longitudinal direction of the at least one track that is 20-50% of the spatial dimension of the partial region irradiated by each individual light pulse of the first region in the longitudinal direction of the at least one track. Correspondingly, a laser beam can be directed to the first region of the first side such that an overlap between each individual one of the irradiated different partial regions and at least one other one of the irradiated different partial regions has a spatial dimension in the transverse direction to the longitudinal direction of the at least one track that is 20-50% of the spatial dimension of the partial region irradiated by each individual light pulse of the first region. Since the irradiated different partial regions overlap in this way, it is ensured that the micropattern formed in the first region of the first side includes a large number of small raised portions. These raised portions are spatially distributed substantially uniformly over the entire surface of the first region and are very finely patterned to provide a uniform surface roughness over the entire surface of the first region, thereby achieving that light incident on each marking region can be absorbed substantially uniformly over the entire surface of the first region.

[0045] To further optimize the contrast achievable by the scale body, it is proposed that at least the first side of the guide rail is surface treated before the fine pattern is formed thereon by the pulsed laser beam, in particular so that a small amount of material is removed from the first side.

[0046] Alternatively or additionally, it has been proposed that at least the first side of the workpiece is surface treated after the micropattern is formed on the first side by the laser beam.

[0047] By this measure highly reflective mirror areas of the scale body are possible.

[0048] In particular, in this context, before forming the micropattern on the first side surface of the guide rail by means of a pulsed laser beam, at least the first side surface of the guide rail should be surface-treated by a polishing treatment. In this context, it is advantageous for the first side surface after the treatment of the first side surface to have an average roughness value (Ra) of at most 0.3 μm, in particular an average roughness value (Ra) of at most 0.1 μm, more preferably an average roughness value (Ra) in the range of about 0.007 μm to 0.1 μm. In this context, it is particularly conceivable for at least the first side surface to be surface-treated by means of an abrasive disk, by means of laser polishing and / or by means of electropolishing. This achieves that the first side surface has a very high light reflectance after the polishing treatment (polishing treatment). Accordingly, it is achieved that the mirror area of ​​the scale body has a very high light reflectance after forming the scale body on the polished first side surface by means of a pulsed laser.

[0049] After the first side surface of the guide rail is polished, a fine pattern can be formed on the first side surface by laser pulses such that, after the formation of the fine pattern, the first side surface has an average roughness value in one of the marking areas of the scale body that is 10 times greater than the average roughness value of the side surface in one of the mirror areas of the scale body, whereby the marking area of ​​the scale body can be detected with a much greater contrast than the mirror area by a sensor device for optically scanning the marking area according to the principle of bright field measurement.

[0050] As already explained, in particular after the respective micropattern has been formed on the first side by means of a pulsed laser beam, this first side must be surface cleaned. This surface cleaning is in particular a laser treatment and / or vibration cleaning or ultrasonic cleaning. Such a surface treatment is particularly beneficial if the micropattern is formed in the respective marking area by a short-pulse laser forming a laser light pulsed by light pulses having a pulse duration in the nanosecond range. When the first side is treated by light pulses having a pulse duration in the nanosecond range, the application of light pulses to the first side has the effect that due to the localized thermal load of the side in the area irradiated by the applied light pulse, the surface pattern in the area irradiated by the applied light pulse is changed in such a way that a large number of particles are generated in the area irradiated by the applied light pulse from the atoms of the material constituting this first side, which particles are not firmly bound to the first side but are only loosely attached to the first side. The formation of these particles, which are only loosely attached to the first side, locally impairs the mechanical and chemical stability of the first side in the area irradiated by the applied light pulse. By surface treating the first side after forming the respective micropatterns on the first side by the pulsed laser beam, it can be achieved that the particles generated in the area irradiated by the light pulse and loosely attached to the first side are completely removed. This can improve the mechanical and chemical stability of the first side in the area irradiated by the applied light pulse.

[0051] With regard to the scale body which can be produced by the method of the invention, it is proposed in accordance with a further configuration of the invention, in particular, that the guide rail comprises at least one, in particular a plurality of blind holes (seen from the second side), in particular with an internal thread. In this connection, in particular, the first side of the workpiece must be provided without holes. These blind holes are used to fasten the guide rail to the pattern by means of screws which can be screwed into the respective blind holes. By these blind holes being formed on the second side and therefore not extending to the first side, the entire first side can be used to form the scale body. This allows the provision of guide rails provided with the scale body having a very small cross section, which is therefore beneficial for the production of profile rail guides which have relatively small dimensions transverse to the longitudinal direction of the respective guide rail.

[0052] The scale body may be formed such that at least one linear track extending in the longitudinal direction of the guide rail is configured as an incremental track having a plurality of equally spaced marking areas.

[0053] Alternatively, the scale body may be formed such that at least one linear track extending in the longitudinal direction of the guide rail is configured as a reference track having at least one marking area for encoding at least one reference position, or as a reference track having a plurality of marking areas arranged one behind the other in the longitudinal direction of the guide rail for encoding a plurality of different reference positions.

[0054] According to another embodiment, the scale body of the invention comprises a first track extending in the longitudinal direction of the guide rail, the first track being configured as an incremental track with a number of equally spaced marking areas, and a reference track arranged parallel to the first incremental track and having one or more marking areas for coding one or more reference positions. In this case, the reference track is in particular configured to indicate the absolute position of the measuring head along the scale body. To measure the respective absolute position of the measuring head at any location, for example, the change in the relative position (measured over the first incremental track) of the measuring head with respect to a specific one of the reference marks of the reference track can be measured. Thus, the reference track makes it possible for the linear encoder to not only detect the position change of the measuring head, but also to detect the absolute position of the measuring head relative to the longitudinal direction of the scale body or the guide rail.

[0055] As already explained, the scale body of the present invention is particularly adapted for use in conjunction with a linear encoder enabling optical scanning of the scale body, such a linear encoder comprising at least one scale body of the present invention and a sensor arrangement adapted for optical scanning of at least one track of the scale body.

[0056] In this case, at least one sensor device of the linear encoder comprises a measuring head with an optical imaging device for generating an image of at least one track, the measuring head being movable relative to the scale body, and a number of optical sensors for detecting the image. In this case, in particular, the sensor device can be configured such that the optical sensors generate an output signal upon detection of the image. When the position of the measuring head changes with respect to the longitudinal direction of the guide rail, the output signals generated by the optical sensors change depending on the respective arrangement of the different marking areas of the scale body in the longitudinal direction of the guide rail.

[0057] The features of the present invention will now be described in detail with reference to the accompanying drawings. [Brief description of the drawings]

[0058] [Figure 1] 1 shows a schematic diagram of the operating mode of a displacement measuring system having a linear encoder operating according to the bright field measurement principle for measuring the displacement (shown in a cross section perpendicular to the longitudinal direction of a guide rail of a linear profile rail guide) progressing in the longitudinal direction of the guide rail. [Diagram 2] 2A and 2B show schematic diagrams of exemplary embodiments of the arrangement of a plurality of marking areas of a scale body for a linear encoder according to FIG. 1 formed on a surface of a guide rail of a profile rail guide; [Figure 3A] Schematically shows a first marking area of ​​the scale body according to Figure 2 and an arrangement of a plurality of surface areas of the guide rail to be illuminated by light pulses of a pulsed laser beam, to enable the provision of a first marking area on the surface of the guide rail according to the present invention. [Figure 3B] FIG. 3A shows, in a similar manner to FIG. 3A, a schematic representation of a second marking area of ​​the scale body according to FIG. 2 and an arrangement of a plurality of surface areas of the guide rail to be illuminated by light pulses of a pulsed laser beam, in order to enable a second marking area to be provided on the surface of the guide rail according to the present invention. [Figure 4] 2 is a microscopic plan view of a scale body formed on a surface of a guide rail of a profile rail guide by the method of the present invention; FIG. [Diagram 5] 3 shows diagrammatically a number of marking areas formed on a side surface of a guide rail of a profile rail guide by the method of the invention before cleaning the surface; [Figure 6] 6 shows a schematic representation of a number of marking areas according to FIG. 5 after the surface has been cleaned. [Figure 7]In order to show an enlarged view of the surface of the guide rail in the area of ​​the marking region, a portion of the plan view according to FIG. 4 is shown enlarged, so that the surface roughness of the guide rail is visible in the displayed marking region. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0059] Unless otherwise noted, the same reference numbers are used in the figures to refer to the same components.

[0060] 1 and 2 show diagrammatically an operating configuration of a displacement measuring system 10 for measuring the displacement of a movable body 3 of a linear profile rail guide 1 guided in the longitudinal direction of a guide rail 2 of the linear profile rail guide 1. In this case, the movable body 3 of the profile rail guide 1 is guided in the guide rail 2 such that it is linearly movable in the longitudinal direction of the guide rail 2. For this purpose, the movable body 3 of the profile rail guide 1 can be supported on the guide rail 2, for example, via a drum body (not shown). In the illustration according to FIGS. 1 and 2, it is assumed that the X-axis of the Cartesian coordinate system shown in FIGS. 1 and 2 with three orthogonal axes X, Y and Z (X-axis, Y-axis and Z-axis) extends in the longitudinal direction of the guide rail 2, so that the movable body 3 is linearly movable in the X-axis direction.

[0061] The displacement measuring system 10 according to figures 1 and 2 comprises an optical linear encoder operating according to the principle of bright field measurement, which is capable of measuring the displacement of the movable body 3 in the longitudinal direction of the guide rail 2. To this end, the linear encoder 11 consists of a scale body 15 extending in the longitudinal direction of the guide rail 2 and at least one sensor device 20 arranged for optically scanning at least one track of the scale body 15, the scale body 15 comprising at least one track in which a number of mirror areas and a number of marking areas are arranged one behind the other, the track extending linearly in the longitudinal direction of the guide rail 2.

[0062] As shown in Fig. 1, the scale body 15 is formed on a first side 2.1 of the guide rail 2. To enable optical scanning of the scale body 15, the sensor device 20 has a measuring head 21 which is movable in the longitudinal direction of the guide rail 2. The measuring head 21 is fixed to the movable body 3 in such a way that the measuring head 21 is arranged opposite the side 2.1 of the guide rail 2 on which the scale body 15 is provided and is moved together with the movable body 3 when the movable body 3 moves in the longitudinal direction of the guide rail 2.

[0063] 1 and 2, the scale body 15 is arranged on the first side 2.1 and comprises two different tracks, a first track SP1 and a second track SP2, which run parallel to each other in the longitudinal direction of the guide rail 2 and in which a number of mirror areas and a number of marking areas are arranged one behind the other. The first track SP1 is configured as an incremental track with a number of equally spaced marking areas. The second track SP2 is configured as a reference track and may have at least one marking area for coding at least one reference position or may alternatively have a number of marking areas arranged one behind the other in the longitudinal direction of the guide rail 2 for coding a number of different reference positions.

[0064] As shown in Figure 2, each of the multiple marking areas of the first track SP1 and the second track SP2 of the scale body 15 extends linearly on the first side 2.1 of the guide rail 2 in the Y-axis direction shown in Figures 1 and 2, i.e. transverse to the longitudinal direction of the scale body 15 or transverse to the longitudinal direction of the guide rail 2, respectively.

[0065] As shown in Fig. 2, the first track SP1 (incremental track) has a plurality of marking areas. The geometric shapes and spatial dimensions in the X-axis direction and the spatial dimensions in the Y-axis direction of these marking areas are equal. One mirror area S is formed between each of two adjacent marking areas M arranged directly one behind the other in the X-axis direction. The spatial dimensions in the X-axis direction and the spatial dimensions in the Y-axis direction of all mirror areas S of the first track SP1 are equal.

[0066] As further shown in FIG. 2, in this example the second track (reference track) has marking areas M1, M2, M3, M4, M5, M6, M7, M8, M9, M10, M11, M12, M13 or M14 arranged in a row one behind the other in the longitudinal direction of the guide rail 2.

[0067] In the case of the second track SP2, one mirror area is formed between each pair of adjacent marking areas that are directly adjacent to each other in the X-axis direction. Therefore, the marking areas M1, M2, M3, M4, M5, M6, M7, M8, M9, M10, M11, M12, M13, or M14 are alternately arranged in a row with the mirror areas S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, S13, S14, or S15. However, the spatial dimensions in the X-direction of all marking areas M1, M2, M3, M4, M5, M6, M7, M8, M9, M10, M11, M12, M13 and M14 of the second track SP2 are not equal to one another, and similarly the spatial dimensions in the X-direction of all mirror areas S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, S13, S14 and S15 of the second track SP2 are not equal to one another. These different marking areas and these mirror areas of the second track SP2 thus allow the coding of a number of different reference positions, which respectively uniquely define a number of different absolute positions.

[0068] The measuring head 21 comprises a light source 22 (e.g. an LED). The light source 22 emits light as a light beam 22.1 directed approximately perpendicularly to the side surface 2.1 of the guide rail 2. A part of the light emitted by the light source 22 is incident on a first track SP1 of the scale body 15, and another part of the light 22.1 emitted by the light source 22 is incident on a second track SP2 of the scale body 15. The operating principle of the linear encoder 11 requires that the light 22.1 emitted by the light source 22 is regularly (mirror-like) reflected by the side surface 2.1 of the guide rail 2. In this case, it is preferably desired that each incident beam is reflected at the same angle to the surface normal.

[0069] As shown in Fig. 1, a portion of the light 22.1 emitted by the light source 22 that is incident on the first track SP1 of the scale body 15 is reflected by the first track SP1. The light reflected by the first track SP1 of the scale body 15 is represented by a light beam indicated by "RL1" in Fig. 1. Similarly, a portion of the light 22.1 emitted by the light source 22 that is incident on the second track SP2 of the scale body 15 is reflected by the second track SP2. The light reflected by the second track SP2 of the scale body 15 is represented by a light beam indicated by "RL2" in Fig. 1.

[0070] As further shown in FIG. 1, the measurement head 21 has an electronic optical sensor chip 25 configured to detect light RL1 reflected from the first track SP1 and light RL2 reflected from the second track SP2, and to analyze the spatial distribution of the intensity of the reflected light RL1 and the spatial distribution of the intensity of the reflected light RL2.

[0071] For this purpose, the optical sensor chip 25 has a first array 25.1 of a plurality of optical sensors for detecting light RL1 reflected by a first track SP1 of the scale body 15 and a second array 25.2 of a plurality of optical sensors for detecting light RL2 reflected by a second track SP2 of the scale body 15, and further has further electronic elements (not shown in the figure) configured to evaluate corresponding output signals of the first array 25.1 of a plurality of optical sensors and / or corresponding output signals of the second array 25.2 of a plurality of optical sensors.

[0072] According to the invention, the scale body 15 is designed such that the individual marking areas, i.e. the marking area M of the first track SP1 and the marking areas M1, M2, M3, M4, M5, M6, M7, M8, M9, M10, M11, M12, M13 and M14 of the second track SP2, substantially absorb and do not reflect the light 22.1 emitted by the light source 22 and incident on the respective marking area in the direction of the first array of light sensors 25.1 and / or in the direction of the second array of light sensors 25.2. In this case, the light RL1 reflected by the first track SP1 of the scale body 15 substantially consists of the light reflected by the mirror area S of the first track SP1. Similarly, the light RL2 reflected by the first track SP2 of the scale body 15 substantially consists of light reflected by mirror areas S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, S13, S14 and S15 of the second track SP2.

[0073] Under the above circumstances, the spatial distribution of the intensity of the light RL1 reflected by the first track SP1 of the scale body 15 in the longitudinal direction of the guide rail 2 has a spatial change corresponding to the spatial arrangement of the mirror areas S of the first track SP1 in the longitudinal direction of the guide rail 2. Similarly, the spatial distribution of the intensity of the light RL2 reflected by the second track SP2 of the scale body 15 in the longitudinal direction of the guide rail 2 has a spatial change corresponding to the spatial arrangement of the mirror areas S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, S13, S14, and S15 of the second track SP2 in the longitudinal direction of the guide rail 2.

[0074] The first array of light sensors 25.1 comprises a number of light sensors (not shown in FIG. 1) arranged one behind the other in a row in the longitudinal direction of the guide rail 2. Similarly, the second array of light sensors 25.2 comprises a number of light sensors (not shown in FIG. 1) arranged one behind the other in a row in the longitudinal direction of the guide rail 2.

[0075] When the movable body 3 is moved in the longitudinal direction of the guide rail 2, the first array of light sensors 25.1 and the second array of light sensors 25.2 of the measuring head 21 are also moved in the longitudinal direction of the first track SP1 or the second track SP2 of the scale body 15. In this case, the intensity of the light RL1 reflected from the first track SP1 detected by the individual light sensors of the first array of light sensors 25.1 varies as a function of the position of the movable body 3 relative to the longitudinal direction of the guide rail 2 as the movable body 3 moves in the longitudinal direction of the guide rail 2.

[0076] The first track SP1 is configured as an incremental track, and the marking areas M of the first track SP1 are arranged equidistantly one behind the other in the longitudinal direction of the guide rail 2, so that the intensity of the light RL1 reflected by the first track SP1 detected by each light sensor of the first array of light sensors 25.1 exhibits a periodic variation as a function of the position of the movable body 3 relative to the longitudinal direction of the guide rail 2 as the movable body 3 moves in the longitudinal direction of the guide rail 2. Similarly, each light sensor of the first array of light sensors 25.1 generates an output signal which varies periodically as a function of the position of the movable body 3 relative to the longitudinal direction of the guide rail 2 as the movable body 3 moves in the longitudinal direction of the guide rail 2.

[0077] It is basically possible to configure the light sensors of the first array of light sensors 25.1 in such a way that each light sensor of the first array of light sensors generates an output signal during the movement of the movable body 3 in the longitudinal direction of the guide rail 2, the periodic change of which corresponds to the progression of a mathematical sine or cosine function as a function of the position of the movable body 3 relative to the longitudinal direction of the guide rail 2. By evaluating the output signals of the light sensors of the first array of light sensors 25.1, the displacement which the movable body 3 undergoes when moving in the longitudinal direction of the guide rail 2 can then be determined.

[0078] As described above, the second track SP2 is configured as a reference track, in which all marking areas M1, M2, M3, M4, M5, M6, M7, M8, M9, M10, M11, M12, M13 and M14 of the second track SP2 have unequal spatial dimensions in the X-axis direction, and similarly all mirror areas S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, S13, S14 and S15 of the second track SP2 have unequal spatial dimensions in the X-axis direction.

[0079] In this case, the intensity of light RL2 reflected from the second track SP2 detected by the individual light sensors of the second array of light sensors 25.2 each exhibits a variation as a function of the position of the movable body 3 relative to the longitudinal direction of the guide rail 2 as the movable body 3 moves in the longitudinal direction of the guide rail 2. However, this variation does not have a periodic variation as a function of the position of the movable body 3 relative to the longitudinal direction of the guide rail 2.

[0080] Correspondingly, each individual optical sensor of the second array of optical sensors 25.2 generates an output signal which varies non-periodically as a function of the position of the movable body 3 relative to the longitudinal direction of the guide rail 2 as the movable body 3 moves in the longitudinal direction of the guide rail 2. Thus, evaluation of the output signals of these optical sensors of the second array of optical sensors 25.2 allows the determination of the absolute position of the movable body 3 relative to the respective positions of the plurality of marking areas and the plurality of mirror areas of the second track SP2 of the scale body 15.

[0081] As a material for the guide rails of linear profile rail guides, steel, in particular stainless steel, is generally used. The surface of such guide rails, which is generally ground according to standards (i.e. not polished), has a profile that can differ from a flat surface, such that this surface reflects light rather diffusely.

[0082] If the light 22.1 emitted from the light source 22 is scattered and reflected by each mirror area of ​​the scale body 15, this may affect the measurement accuracy of the displacement measuring system 10.

[0083] Therefore, when realizing the scale body 15 on the first side surface 2.1 of the guide rail 2 according to Figures 1 and 2, it is advantageous, before forming the scale body 15 on the side surface 2.1 of the guide rail 2, to first surface-treat the side surface 2.1 by the method of the invention, in particular so that a small amount of material is removed from the first side surface 2.1 of the guide rail 2, in order to reduce any roughness initially present on the side surface 2.1 and correspondingly form the side surface 2.1 as smoothly or as flat as possible.

[0084] For surface treatment of the profile rail guide, the surface of the guide rail 2 is polished, in particular in the region of the side surface 2.1. This polishing can be carried out in various ways, in particular by a preliminary polishing process with ceramic polishing discs having a very fine grit size (up to 400), followed by polishing with polishing discs based on rubber or synthetic resin. As an alternative to the production form of polishing with polishing discs, there are laser polishing processes or electropolishing processes or polishing with polishing brushes.

[0085] After such surface treatment of the side surface 2.1, the individual marking areas of the scale body 15 are finally produced on the first side surface 2.1 of the guide rail 2 by using a pulsed laser. In the following, an example for producing the individual marking areas of the scale body 15 according to the method of the invention is described with particular reference to Figures 3A and 3B.

[0086] 3A shows a first region B1 of the side surface 2.1 (viewed from above on the side surface 2.1), which should be treated by a pulsed laser in order to form a micropattern in the first region B1 representative of one of the marking regions of the first track SP1 or the second track SP2 of the scale body 15.

[0087] Since the respective marking areas of the first track SP1 or the second track SP2 of the scale body 15 extend linearly transversely to the longitudinal direction of the scale body 15 (i.e., in the X-axis direction in Figures 1 and 2), it can be seen that in the example of Figure 3A, the first area B1 has a substantially rectangular shape having a dimension DBX in the longitudinal direction of the scale body 15 and a dimension DBY transversely to the longitudinal direction of the scale body 15 (i.e., in the Y-axis direction in Figures 1 and 2).

[0088] A pulsed laser is provided for forming a laser beam in the region B1 to form a micropattern representative of one of the marking regions of the first track SP1 or the second track SP2 of the scale body 15. In this case, the laser forms a laser beam with a succession of light pulses. The laser beam is directed towards the region B1 of the first side 2.1 such that only one partial region of the first region B1 is illuminated by each individual light pulse of the succession of light pulses.

[0089] In the example according to Fig. 3A, it is assumed that the laser beam has an approximately circular beam profile with a diameter DL in a plane perpendicular to the propagation direction of the laser beam, so that the individual light pulses of the laser beam illuminate an area of ​​the side surface 2.1 with laser light having a circular shape when entering the side surface 2.1. The diameter of this area illuminated by the individual light pulses in this example corresponds approximately to the diameter DL of the laser.

[0090] In this example, it is assumed that upon incidence of the individual light pulses of the light beam on side surface 2.1, side surface 2.1 is illuminated by the individual light pulses in a circular area of ​​diameter D, so that side surface 2.1 is illuminated in such a way that said circular area of ​​diameter D has a change in the shape of the spatial modulation (compared to the shape of the surface before irradiation by the respective individual light pulse). Thus, in the example according to Fig. 3A, the "partial areas of first region B1 illuminated by the respective individual light pulses" are shown as areas of side surface 2.1, each bounded by a circle of diameter D.

[0091] Furthermore, in the example according to Figure 3A, it is assumed in particular that the laser beam is directed towards the first region B1 of the first side 2.1 such that the spatial dimension D of the partial region illuminated by each individual light pulse of the first region B1 in the longitudinal direction of the scale body 15 (i.e. in the X-axis direction) is smaller than the spatial dimension DBX of the first region B1 in the longitudinal direction of the scale body 15, and that the spatial dimension D of the partial region illuminated by each individual light pulse in the transverse direction to the longitudinal direction of the scale body 15 (i.e. in the Y-axis direction) is smaller than the spatial dimension DBY of the first region B1 in the transverse direction to the longitudinal direction of the scale body 15.

[0092] In the example according to FIG. 3A, the laser beam is moved relative to the guide rail 2 in such a way that at least some of the successive light pulses formed irradiate in time succession a plurality of different partial areas of the first area B1, which are arranged spatially distributed with respect to one another. In this case, for each individual partial area of ​​the irradiated plurality of different partial areas, there is at least one further partial area of ​​the irradiated plurality of different partial areas, which is offset relative to each individual partial area of ​​the irradiated plurality of different partial areas in the longitudinal direction of the scale body 15 (i.e. in the X-axis direction) and / or transversely relative to the longitudinal direction of the scale body 15 (i.e. in the Y-axis direction), such that each individual partial area of ​​the irradiated plurality of different partial areas and at least one further partial area of ​​the irradiated plurality of different partial areas have an overlapping portion. And in this case, the irradiated plurality of different partial areas together form an area of ​​the first side surface that is congruent with the first area B1.

[0093] The laser beam is thus moved in two dimensions (i.e. along the X-axis and along the Y-axis) over the marking area of ​​the first region B1, which corresponds to the scale body 15 to be formed on the first side 2.1 of the guide rail 2. As a result, several different partial regions of the first region B1 are successively illuminated.

[0094] Irradiation of one partial region by one of the plurality of optical pulses locally slightly removes and / or spatially redistributes the material (steel) forming the first side surface 2.1 of the guide rail 2. As a result, the shape of the surface of the irradiated partial region after irradiation by the optical pulse changes. As the laser beam is moved over the first region B1, each of the plurality of different irradiated partial regions necessarily has an overlapping portion with at least one other partial region of the plurality of different irradiated partial regions, whereby the first side surface 2.1 of the guide rail 2 achieves spatial modulation in the first region B1 after irradiation by the optical pulse. As a result, the roughness (Rauigkeit) of the first side surface 2.1 in the first region B1 increases compared to the state before irradiation by the optical pulse. Irradiation of the first region by the optical pulse enables fine patterning of the first side surface, such that the smooth surface before irradiation has an array of raised portions (a "fine pattern") over the entire first region after irradiation, and this array exhibits a substantially uniform surface roughness in the first region B1.

[0095] In the example according to FIG. 3A, the diameter DL of the laser beam or the diameter D of each partial region of the first region B1 irradiated by the optical pulse is such that D < DBX < 2D and D < DBY < nD, where n is a natural number (equal to or greater than 2), and is thus selected.

[0096] It is further assumed that the different partial areas illuminated by the light pulse are arranged in the first area B1 in such a way that there is a first group of n partial areas in total among all illuminated partial areas, the individual partial areas of the first group being arranged in a row extending transversely to the longitudinal direction of the scale body 15 (i.e. in the Y-axis direction) and being arranged with respect to one another in such a way that the center points of the different partial areas are offset from one another by a predetermined distance transversely to the longitudinal direction of the scale body 15. As shown in Fig. 3A, the first group of the multiple partial areas as a whole forms a first linear section of the first area B1, which is indicated in Fig. 3A by the reference "L1". The dimension of this first linear section transversely to the longitudinal direction of the scale body 15 is equal to the dimension DBY of the first area B1, and the dimension of this first linear section in the longitudinal direction of the scale body 15 is equal to the diameter D of the respective partial area illuminated by the light pulse.

[0097] It should be noted that in FIG. 3A not all of the sub-areas arranged in the first linear section L1 of the first group of said sub-areas are shown. Only four of each of the first group of said sub-areas are shown (for reasons of better illustration). In this case, these four sub-areas in FIG. 3A are indicated by the reference characters "TB11", "TB15", "TB16" and "TB1n". In this case, the two sub-areas "TB11" and "TB1n" are arranged offset from each other in the Y-axis direction, such that the sub-area "TB11" is arranged at one end of the first linear section L1 with respect to the Y-axis, and the sub-area "TB1n" is arranged at the other end of the first linear section L1 (i.e. opposite the sub-area "TB11"). The two sub-areas "TB15" and "TB16" are arranged from each other in such a way that the center point of the sub-area "TB16" is relatively offset by a distance ΔY in the Y-axis direction with respect to the center point of the sub-area "TB15". In this example, the distance ΔY is selected such that it is in particular more than half the diameter D of each partial area illuminated by a light pulse, and the distance ΔY is less than 80% of the diameter D of each partial area illuminated by a light pulse (i.e. D / 2≦ΔY<0.8*D). Thus, both partial areas "TB15" and "TB16" have an overlapping portion, which is illustrated as a shaded area indicated by the symbol "UY" in FIG. 3A. The overlapping portion UY has a dimension DUY in the Y-axis direction. The dimension DUY is in the range of 20-50% of the spatial dimension D of the partial area illuminated by an individual light pulse in the Y-axis direction.

[0098] The dimension DUY is related to the diameter D of the respective partial area illuminated by the light pulse and the above-mentioned distance ΔY according to the formula: DUY=D-ΔY.

[0099] With regard to the partial areas of the first group of partial areas that are not shown in Fig. 3A, it is noted that for each individual partial area of ​​the different partial areas that are illuminated by a light pulse, there is one other partial area that is illuminated by a light pulse, and the center points of the different partial areas can be arranged relative to each other in a direction perpendicular to the longitudinal direction of the scale body 15 such that the center point of this other partial area is offset by a distance corresponding to the distance ΔY between the center points of the partial areas "TB15" and "TB16" shown in Fig. 3A with respect to the center points of each individual partial area of ​​the different partial areas that are illuminated by a light pulse in a direction perpendicular to the longitudinal direction of the scale body 15 (i.e., in the Y-axis direction). Thus, each partial area of ​​the first group of partial areas has an overlapping portion with another partial area of ​​the first group of partial areas. The overlapping portion corresponds to the overlapping portion UY of the partial areas "TB15" and "TB16" shown in Fig. 3A.

[0100] As can be seen from Fig. 3A, the different partial areas illuminated by the light pulse are arranged in the first area B1 in such a way that in addition to the first group of partial areas, there is a second group with a total of n partial areas from all illuminated partial areas. The individual partial areas of this second group are arranged in a row extending perpendicularly to the longitudinal direction of the scale body 15 (i.e. in the Y-axis direction) and are arranged with respect to one another in such a way that the center points of the different partial areas are respectively offset relative to one another by a similarly preset distance perpendicularly to the longitudinal direction of the scale body 15. As shown in Fig. 3A, the second group of partial areas as a whole forms a second linear section of the first area B1, which is indicated in Fig. 3A by the reference "L2". The dimension of this second linear section perpendicular to the longitudinal direction of the scale body 15 is equal to the dimension DBY of the first area B1 and the dimension of this second linear section in the longitudinal direction of the scale body 15 is equal to the diameter D of the respective partial area illuminated by the light pulse.

[0101] 3A, the individual partial areas of the second group of partial areas illuminated by the light pulses are arranged in a more or less spatially distributed manner in the second linear section L2 of the first region B1 in a direction perpendicular to the longitudinal direction of the scale body 15. The second group corresponds to the first group of partial areas in the first linear section L1 in the Y-axis direction, similar to the spatial distribution of the individual partial areas illuminated by the light pulses.

[0102] In FIG. 3A, likewise, not all the sub-areas arranged in the second linear section L2 of the second group of sub-areas are shown. Only four of the respective sub-areas of the second group of sub-areas are shown (for reasons of better illustration). In this case, these four sub-areas in FIG. 3A are indicated by the reference characters "TB21", "TB25", "TB26" and "TB2n". In this case, the two sub-areas "TB21" and "TB2n" are arranged offset from each other in the Y-axis direction, such that the sub-area "TB21" is arranged at one end of the second linear section L2 with respect to the Y-axis, and the sub-area "TB2n" is arranged at the other end of the second linear section L2 (i.e. opposite the sub-area "TB21").

[0103] Furthermore, for each individual sub-region among a plurality of different sub-regions irradiated by an optical pulse, there is another sub-region irradiated by the optical pulse, and the center point of this other sub-region is perpendicular to the longitudinal direction of the scale body 15 (i.e., in the Y-axis direction) with respect to the center point of each individual sub-region among the plurality of different sub-regions irradiated by the optical pulse. The center points of the plurality of different sub-regions that make up the second group of a plurality of sub-regions are each shifted from each other in a direction perpendicular to the longitudinal direction of the scale body 15 in the second straight line section L2 of the first region B1 by a distance corresponding to the distance ΔY between the center point of the sub-region "TB15" and the center point of the sub-region "TB16" shown in FIG. 3A. Therefore, each of these sub-regions that make up the second group of the plurality of sub-regions has an overlapping portion with at least another sub-region that makes up the second group of the plurality of sub-regions. The overlapping portion coincides with the overlapping portion UY of the sub-regions "TB15" and "TB16" shown in FIG. 3A.

[0104] As described above, in the example according to FIG. 3A, the diameter DL of the laser beam or the diameter D of each sub-region of the first region B1 irradiated by the optical pulse is selected such that the relationship D < DBX < 2D is satisfied with respect to the dimension DBX of the first region B1 in the longitudinal direction of the scale body 15. Since both the first straight line section L1 and the second straight line section L2 of the first region B1 have a dimension in the longitudinal direction of the scale body 15 equal to the diameter D of each sub-region irradiated by the optical pulse, the center points of these sub-regions that make up the first group of a plurality of sub-regions exist on a first straight line extending in the Y-axis direction, and the center points of these sub-regions that make up the second group of a plurality of sub-regions exist on a second straight line extending in the Y-axis direction as well. In this case, the first straight line and the second straight line are arranged parallel to each other and have a distance ΔX smaller than the diameter D of each sub-region irradiated by the optical pulse in the longitudinal direction of the scale body 15.

[0105] Similarly, the first linear section L1 of the first region B1 and the second linear section L2 of the second region B1 have an overlapping portion that extends in the Y direction over a length corresponding to the dimension DBY of the first region B1 in the Y direction, and extends in the longitudinal direction of the scale body 15 over a length DUX (shown in FIG. 3A ). The dimension DUX of the overlapping portion between the first linear section L1 of the first region B1 and the second linear section L2 of the first region B1 in the longitudinal direction of the scale body 15 is related to the diameter D of the respective partial regions illuminated by the light pulse and the above-mentioned distance ΔX according to the formula: DUX=D-ΔX.

[0106] Similarly, the partial areas of the first group of partial areas and the partial areas of the second group of partial areas are generally arranged such that each partial area of ​​the first group of partial areas has an overlapping portion with at least one partial area of ​​the second group of partial areas, the overlapping portion having a dimension in the longitudinal direction of the scale body 15 equal to the above-mentioned dimension DUX of the overlapping portion between the first linear section L1 of the first region B1 and the second linear section L2 of the second region B1 in the longitudinal direction of the scale body 15.

[0107] 3A similarly illustrates that the partial regions TB11 and TB21 are arranged to be shifted in the longitudinal direction of the scale body 15 so that the partial regions TB11 and TB21 have an overlapping portion shown as a shaded region indicated by the symbol "UX" in FIG. 3A. This overlapping portion UX has a dimension in the X-axis direction equal to the above-mentioned dimension DUX.

[0108] 3A further illustrates that the partial regions TB1n and TB2n are arranged to be shifted in the longitudinal direction of the scale body 15 so that the partial regions TB1n and TB2n have an overlapping portion shown as a shaded region similarly indicated by the symbol "UX" in FIG. 3A. This overlapping portion UX similarly has a dimension in the X-axis direction equal to the above-mentioned dimension DUX.

[0109] 3A further illustrates that the partial regions TB15 and TB25 are arranged to be shifted in the longitudinal direction of the scale body 15 such that the partial regions TB15 and TB25 have an overlapping portion shown as a shaded region similarly indicated by the symbol "UX" in FIG. 3A. This overlapping portion UX similarly has a dimension in the X-axis direction equal to the above-mentioned dimension DUX.

[0110] 3A further illustrates that the partial regions TB16 and TB26 are arranged to be shifted in the longitudinal direction of the scale body 15 such that the partial regions TB16 and TB26 have an overlapping portion shown as a shaded region similarly indicated by the symbol "UX" in FIG. 3A. This overlapping portion UX has a dimension in the X-axis direction similarly equal to the above-mentioned dimension DUX.

[0111] As can be seen from Fig. 3A, the partial regions TB25 and TB26 are disposed relative to each other such that the center point of the partial region "TB26" is relatively shifted by a distance ΔY in the Y-axis direction with respect to the center point of the partial region TB25. As a result, the partial regions TB25 and TB26 have an overlapping portion shown as a shaded region indicated by the symbol "UY" in Fig. 3A.

[0112] Thus, as can be seen from FIG. 3A, each of the sub-regions TB15, TB16, TB25 and TB26 of the first region B1 illuminated by an individual light pulse has overlapping portions UX and UY in two dimensions (i.e., in the longitudinal direction of at least one track and in a direction perpendicular to the longitudinal direction of the at least one track).

[0113] Similarly, all partial areas of the first region B1 illuminated by an individual light pulse each have overlapping portions UX and UY in two dimensions (i.e. in the longitudinal direction of at least one track and in a direction perpendicular to the longitudinal direction of the at least one track).

[0114] The distance ΔX is advantageously selected such that the dimension DUX of the overlap portion UX in the X-axis direction is in particular in the range of 20-50% of the spatial dimension in the X-axis direction of the partial areas illuminated by the individual light pulses.

[0115] Figure 3B, like Figure 3A, shows a first area B2 of the side surface 2.1 (viewed from above this side surface 2.1), in which the side surface 2.1 is to be treated by a pulsed laser in order to form in the first area B2 a fine pattern which is one of a number of marking areas of the first track SP1 or the second track SP2 of the scale body 15.

[0116] Similar to that illustrated in Figure 3A, in the example according to Figure 3B it is assumed that the first region B2 is approximately rectangular in shape having a dimension DBX in the longitudinal direction of the scale body 15 and a dimension DBY in a direction perpendicular to the longitudinal direction of the scale body 15 (i.e. in the Y-axis direction according to Figures 1 and 2).

[0117] Analogously to the example according to Fig. 3A, in the example according to Fig. 3B, a pulsed laser is provided for forming a laser beam in order to produce a micropattern to be formed in the region B2, which in this case forms a series of light pulses, which are directed towards the first region B2 of the first side surface 2.1 in such a way that only one partial region of the first region B2 is illuminated by each individual light pulse of the formed series of light pulses.

[0118] 3B, as in the example according to Fig. 3A, it is assumed that the laser beam has an approximately circular beam profile with a diameter DL in a plane perpendicular to the propagation direction of the laser beam, so that the individual light pulses of the laser beam illuminate an area of ​​the side surface 2.1 with circular laser light when they impinge on the side surface 2.1. The diameter of this area illuminated by the individual light pulses then corresponds in this example to the diameter DL of the laser.

[0119] 3A, in the example according to Fig. 3B, it is assumed that, upon incidence of the individual light pulses of the light beam on side surface 2.1, this side surface 2.1 is illuminated by the individual light pulses in said circular area of ​​diameter D, so that side surface 2.1 is illuminated in such a way that this circular area of ​​diameter D has a change in the form of a spatial modulation (compared to the shape of the surface before irradiation by the respective individual light pulses). Thus, in the example according to Fig. 3B, the "partial areas of the first region B2 illuminated by the respective individual light pulses" are shown as areas of side surface 2.1, each bounded by a circle of diameter D.

[0120] As in the example according to Figure 3A, in the example according to Figure 3B, it is assumed that the laser beam is directed towards the first region B2 of the first side 2.1 such that the spatial dimension D of the partial region of the first region B2 illuminated by each individual light pulse in the longitudinal direction of the scale body 15 (i.e. in the X-axis direction) is smaller than the spatial dimension DBX of the first region B2 in the longitudinal direction of the scale body 15, and that the spatial diameter D of the partial region illuminated by each individual light pulse in a direction perpendicular to the longitudinal direction of the scale body 15 (i.e. in the Y-axis direction) is smaller than the spatial dimension DBY of the first region B2 perpendicular to the longitudinal direction of the scale body 15.

[0121] The example according to Fig. 3B differs from the example according to Fig. 3A substantially in that, although the dimension DBY of the first area B2 according to Fig. 3B in the transverse direction to the longitudinal direction of the scale body 15 (i.e. in the Y-axis direction) is equal to the dimension of the first area B1 according to Fig. 3A in the transverse direction to the longitudinal direction of the scale body 15, the spatial dimension DBX of the first area B2 in the longitudinal direction of the scale body 15 is much larger than the dimension of the first area B1 according to Fig. 3A in the longitudinal direction of the scale body 15. The latter takes into account the requirement that the scale body 15 has a number of different marking areas in the area of ​​the second track SP2, the dimensions of these marking areas in the longitudinal direction of the scale body 15 being significantly different.

[0122] In the example according to FIG. 3A, it is likewise assumed that the spatial dimension DBX of the first region B2 in the longitudinal direction of the scale body 15 is much larger than twice the spatial dimension D in the longitudinal direction of the scale body 15 of the partial region of the first region B2 illuminated by each individual light pulse (i.e. DBX>2*D).

[0123] In the example according to FIG. 3B, the laser beam is likewise moved relative to the guide rail 2 in such a way that at least some of the successive light pulses formed illuminate in time succession a plurality of different partial areas of the first area B2, which are arranged in a spatially offset relationship with one another. In this case, for each individual partial area of ​​the illuminated plurality of different partial areas, there is at least one further partial area of ​​the illuminated plurality of different partial areas, which is offset in the longitudinal direction of the scale body 15 (i.e. in the X-axis direction) and / or transversely to the longitudinal direction of the scale body 15 (i.e. in the Y-axis direction) with respect to each individual partial area of ​​the illuminated plurality of different partial areas, such that there is an overlap between the respective individual partial area of ​​the illuminated plurality of different partial areas and the at least one further partial area of ​​the illuminated plurality of different partial areas. In this case, the illuminated plurality of different partial areas together form an area of ​​a first side surface that is congruent with the first area B2.

[0124] 3B, the laser beam is thus moved in two dimensions as well (i.e. along the X-axis and along the Y-axis) over the marking area of ​​the first region B2, which corresponds to the scale body 15 to be formed on the first side 2.1 of the guide rail 2. As a result, several different partial regions of the first region B2 are successively illuminated.

[0125] In contrast to the example according to Fig. 3A, in the example according to Fig. 3B, the spatial dimension DBX of the first area B2 in the longitudinal direction of the scale body 15 is relatively large compared to the spatial dimension D of the partial area illuminated by each individual light pulse, so that the different partial areas illuminated by a light pulse are arranged in the first area B2 in such a way that there are two or more different groups of partial areas among all the illuminated partial areas, where each group of two or more different groups of partial areas comprises a plurality of partial areas (n partial areas as in the example according to Fig. 3A), the individual partial areas of each group of the two or more different groups being arranged in a row perpendicular to the longitudinal direction of the scale body 15 (i.e. in the Y-axis direction) and at the same time being arranged with respect to one another in such a way that the center points of the different partial areas are respectively offset relative to one another by a preset distance perpendicular to the longitudinal direction of the scale body 15. In this case, the two or more different groups consisting of a plurality of partial areas differ in that the center point of the partial area of ​​one of the different groups of partial areas is shifted a predetermined distance in the longitudinal direction of the scale body 15 (i.e., in the X-axis direction) relative to the center point of the partial area of ​​each of the other groups of partial areas.

[0126] In the example according to Fig. 3B, it is assumed that there are seven different groups of partial areas (alternatively, there may be more or less than seven different groups). As shown in Fig. 3, each partial area of ​​each group of the seven different groups of partial areas forms a linear section of the first area B2. The dimension of this linear section in a direction perpendicular to the longitudinal direction of the scale body 15 is equal to the dimension DBY of the first area B2 and the dimension of this linear section in the longitudinal direction of the scale body 15 is equal to the diameter D of the respective partial area illuminated by the light pulse.

[0127] The center point of one of the seven different groups of partial areas is shifted by a preset distance in the longitudinal direction (i.e., in the X-axis direction) of the scale body 15 with respect to the center point of each of the other groups of partial areas, so that the partial areas of the seven different groups form a total of seven straight line sections of the first region B2. These straight line sections are indicated in FIG. 3B by the symbols "L1", "L2", "L3", "L4", "L5", "L6" or "L7".

[0128] 3B does not show the partial areas illuminated by light pulses, which are assigned to each of the seven straight sections L1, L2, L3, L4, L5, L6 or L7 of the first region B2. In this connection, it is assumed that the arrangement of the individual partial areas illuminated by light pulses of the seven straight sections L1, L2, L3, L4, L5, L6 or L7 is similar to the arrangement of the individual partial areas illuminated by light pulses in the first straight section L1 or the second straight section L2 of the first region B1 according to FIG. 3A.

[0129] As shown in Fig. 3B, the center points of the individual partial areas irradiated by the light pulse in each of the seven straight line sections L1, L2, L3, L4, L5, L6, or L7 of the first region B2 are located on a straight line extending in the Y-axis direction. In the example according to Fig. 3B, the seven straight line sections L1, L2, L3, L4, L5, L6, or L7 of the first region B2 are arranged such that the center point of the partial areas irradiated by the light pulse assigned to the straight line section L1 has a distance ΔX smaller than the diameter D of each partial area irradiated by the light pulse in the longitudinal direction of the scale body 15 (i.e., in the X-axis direction) from the center point of the partial areas irradiated by the light pulse assigned to the straight line section L2. Similarly, the center point of the partial areas irradiated by the light pulse assigned to the straight line section L2 has the above-mentioned distance ΔX in the longitudinal direction of the scale body 15 (i.e., in the X-axis direction) from the center point of the partial areas irradiated by the light pulse assigned to the straight line section L3. The remaining straight line sections L4, L5, L6 or L7 of the first region B2 are arranged similarly to the straight line sections L1, L2 and L3 of the first region B2: the center points of the individual partial regions illuminated by the light pulses of the seven straight line sections L1, L2, L3, L4, L5, L6 or L7 are respectively located on different straight lines extending in the Y-axis direction and equally spaced one behind the other in the longitudinal direction of the scale body 15. In this case, the distance between each two adjacent ones of these straight lines corresponds to the above-mentioned distance ΔX (as shown in FIG. 3B).

[0130] Since it is assumed that the distance ΔX is smaller than the diameter D of the respective partial area illuminated by the light pulse, the straight line sections L1, L2, L3, L4, L5, L6 or L7 of the first region B2 are arranged in a staggered manner in the longitudinal direction of the scale body 15 such that each straight line section L1, L2, L3, L4, L5, L6 or L7 has an overlapping portion with another straight line section L1, L2, L3, L4, L5, L6 or L7 of the straight line sections L1, L2, L3, L4, L5, L6 or L7, which is shown as a hatched area in Fig. 3B and is respectively indicated by the symbol "UX". Similarly, each overlapping portion UX between two respective straight line sections L1, L2, L3, L4, L5, L6 or L7 has a dimension DUX in the X-axis direction, which is related to the above-mentioned distance ΔX by the following equation: DUX=D-ΔX.

[0131] Similarly, each partial area illuminated by a light pulse and assigned to one of the straight line sections L1, L2, L3, L4, L5, L6 or L7 has an overlap with at least one other partial area illuminated by a light pulse and assigned to another straight line section L1, L2, L3, L4, L5, L6 or L7 in the area of ​​one overlap portion UX of the multiple overlap portions UX shown in FIG. 3B.

[0132] In the example according to FIG. 3B, in particular the distance ΔX is selected such that the dimension DUX of the overlap portion UX in the X-axis direction is in the range of 20-50% of the spatial dimension D of the partial area illuminated in the X-axis direction by the individual light pulses.

[0133] In the following, the construction of the scale body 15 on the side surface 2.1 of the (steel) guide rail will be explained with reference to FIGS.

[0134] Figures 4-7 show examples of implementation of the scale body 15 shown in Figures 1 and 2 on the side of the guide rail of a profile rail guide. In these examples of implementation, a short-pulse laser with, for example, a wavelength of 355 nm, a maximum output power of 300 mW, a pulse duration of less than 15 nanoseconds and an aperture diameter of 16 mm was used to form a fine pattern in each marking area of ​​the scale body 15 on the side of the guide rail. To form the fine pattern, the laser beam could be moved with a scanning speed of 200 mm / s relative to the guide rail. In this case, the laser formed a train of light pulses with a repetition rate (pulse frequency) of 60 kHz, and for the laser power, 90% of the maximum output power was selected as usual.

[0135] The laser beam had a circular profile and was applied to the side of the guide rail in such a way that individual light pulses of the laser beam illuminated partial areas with a diameter D of about 8 μm on the side of the guide rail.

[0136] Fig. 4 is a microscope plan view of the scale body according to Fig. 2 formed on the side of a guide rail by the method of the present invention using the above-mentioned short-pulse laser. The upper half of Fig. 4 shows the first track SP1 (incremental track) of the scale body 15 as viewed from above, and the lower half of Fig. 4 shows the second track SP2 (reference track) of the scale body 15 as viewed from above.

[0137] The bright areas in Figure 4 correspond to the respective mirror areas of the scale body 15, while the dark areas in Figure 4 indicate the respective marking areas of the scale body 15 formed on the side of the guide rail by the above-mentioned short pulse laser.

[0138] The side surface shown in Fig. 4 was polished prior to forming the scale body 15. As a result, the average roughness value (Ra) of this side surface (measured by laser scanning microscope) was Ra = 0.007 µm. The individual marking areas of the first track SP1 (incremental track) shown in the upper half of Fig. 4 have a dimension of about 100 µm in the longitudinal direction of the scale body 15 (i.e. in the X-axis direction of the coordinate system shown in Fig. 4).

[0139] The marking area of ​​the scale body 15 shown in Figure 4 was provided corresponding to the example shown in Figure 3B, in which case the parameters D and ΔX were selected to be: D = 8 μm and ΔX = 5 μm.

[0140] In the case of the side surface shown in Figure 4, irradiation with a laser pulse had the effect that the side surface in each marked area had a uniform roughness over the entire surface of each marked area, where the average roughness value (Ra) within the marked area (measured by laser scanning microscope) was Ra = 0.162 μm.

[0141] Due to this roughness, each marking area of ​​the scale body shown in Figure 4 does not directly reflect light that is incident on the marking area (e.g., perpendicular to the side) and therefore can be recognized in Figure 4 as a dark (black) uniform surface area in light that is incident approximately perpendicular to the side.

[0142] FIG. 5 is a microscope plan view of the scale body 15 formed on the side of the guide rail by the method of the invention using the short-pulse laser as described above in FIG. 4, but with the scale body 15 enlarged so that the outer contours of the respective marking areas and the respective mirror areas of the scale body 15 are more clearly visible. In FIG. 5, a total of five marking areas of the first track (incremental track) of the scale body 15 are visible in the upper area of ​​this FIG. 5, and a total of two marking areas of the second track (reference track) of the scale body 15 are visible in the lower edge of FIG. 5. When closely observing the marking areas formed by the short-pulse laser, it is possible to see that due to the action of the light pulses formed by the short-pulse laser, material residues (in the form of small particles adhering to the surface) occur at the outer edge of the marking areas, which can protrude into the respective adjacent (polished) mirror areas. As a result, in FIG. 5, the respective marking areas do not appear to be defined by straight straight lines at their edges. This applies in particular to the edges of the marking areas which, according to Figure 5, each extend perpendicular to the longitudinal direction of the scale body 15 (i.e. in the Y-axis direction of the coordinate system shown in Figure 5) and can therefore affect the measurement accuracy of the linear encoder resulting from optical scanning of the scale body 15 in the longitudinal direction of this scale body 15.

[0143] The material residues that may occur during the formation of the marking areas by the short-pulse laser can be completely removed by a surface cleaning process using a suitable cleaning agent.

[0144] Furthermore, it is pointed out that irradiation of the surface of a guide rail made of steel or stainless steel material with a short-pulse laser can have the effect that chromium depletion (i.e. a reduction in the concentration of the chromium component contained in the steel) can be caused. Such chromium depletion can reduce the corrosion resistance of the surface of the guide rail (especially in the marking area of ​​the scale body) and is therefore detrimental with respect to the desired durability of the scale body over the longest possible time. To counteract the above-mentioned effect, in particular after the scale body has been formed on the side surface of the guide rail, a passivation treatment (passivation) of this side surface is carried out by means of a suitable passivation agent.

[0145] Suitable cleaning agents for cleaning stainless steel surfaces are, for example, the strongly alkaline cleaning agent known under the name "deconex MT 19", which is manufactured and sold for the above purposes by the company Borer Chemie AG, Gewerbestrasse 13, 4528 Zuchwil.

[0146] Suitable passivation agents for passivating the surfaces of stainless steel are, for example, the strongly acidic cleaning agent known under the name "deconex MT 41", which is likewise produced and sold for the above-mentioned purposes by the company Borer Chemie AG, Gewerbestrasse 13, 4528 Zuchwil.

[0147] In particular, the following sequence of cleaning steps has been found to be suitable for cleaning and passivating the lateral surfaces of the guide rail after the scale body has been formed on the lateral surface by means of a short-pulse laser of the above-mentioned type: 1. Wash with 2% "deconex MT 19" at 55℃ and 25kHz; 15W / L. Passivated with 8% deconex MT 41 at 2.55°C and 40kHz; 15W / L. 3. Rinse with ultrapure water at room temperature and 40 kHz; 15 W / L. 4. Dry at 100℃.

[0148] Fig. 6 is a plan view of the scale body according to Fig. 5 after the above-mentioned ultrasonic cleaning step has been carried out. In comparison with Fig. 5, it can be clearly seen that the marking areas after the above-mentioned cleaning step have been carried out are defined in an approximately straight line. At the outer edge of the marking areas, material residues protruding into the respective adjacent mirror areas are no longer discernible.

[0149] Figure 7 shows an enlarged view of a portion of the marking area shown in Figure 6. The enlarged view shows the structural details of the surface of the individual marking areas after the ultrasonic cleaning process described above has been performed. In particular, the surface roughness is visible, which is uniform over the entire surface of the marking area.

[0150] As already explained, the roughness of the side surface 2.1 of the guide rail 2 before forming the scale body 15 on the side surface 2.1 according to the described method has a significant influence on the intensity of the reflected light RL1 or RL2. In the linear encoder 11 according to FIG. 1, the light RL1 or RL2 is reflected by the respective mirror area of ​​the first track SP1 or the respective mirror area of ​​the second track SP2 of the scale body 15 formed on the side surface 2.1 according to the described method and detected by the respective light sensor of the first array 25.1 of a plurality of light sensors or the respective light sensor of the second array 25.2 of a plurality of light sensors. Similarly, the roughness of the side surface 2.1 of the guide rail 2 before forming the scale body 15 on the side surface 2.1 according to the described method also has a significant influence on the magnitude of the respective output signal, which the respective light sensor of the first array 25.1 of light sensors generates upon detection of the light RL1 reflected by the first track SP1 of the scale body 15 and upon detection of the light RL2 reflected by the second track SP2 of the scale body 15. Likewise, the roughness that the side surface 2.1 of the guide rail 2 has before forming the scale bodies 15 on said side surface 2.1 according to the described method also has a significant influence on the amplitude of the variations which indicate the output signals of the respective optical sensors of the first array 25.1 and of the respective optical sensors of the second array 25.2 as they move in the longitudinal direction of the guide rail 2 in dependence on the respective position of the measuring head 21 relative to the longitudinal direction of the guide rail 2.

[0151] In order to experimentally evaluate the above-mentioned influence of the roughness of the side surface 2.1 of the guide rail 2 before forming the scale body 15 on the side surface 2.1 according to the described method, the scale bodies 15 shown in FIG. 2 were formed on the side surface 2.1 of several different guide rails 2, respectively, according to the described method, where one side surface 2.1 of the several guide rails was ground according to the standard before forming the scale body 15, but was not polished (after grinding according to the said standard), and one side surface of another guide rail 2 was first ground according to the standard and subsequently further polished (after grinding according to the said standard), in particular by a pre-polishing treatment with a ceramic grinding disk having a very fine grit size (up to 400) and then a polishing treatment with a polishing disk based on rubber or synthetic resin, or alternatively by a polishing brush.

[0152] In this case, the scale body 15 is formed on each side 2.1 of each guide rail 2 by the same short pulse laser (using the same operating parameters of the short pulse laser) used to realize the scale body 15 shown in Figures 4-7.

[0153] The laser beam thus had a circular profile and was applied to the side surface 2.1 of the respective guide rail 2 in such a way that each light pulse of said laser beam illuminated a partial area having a diameter D of approximately 8 μm on the side surface 2.1 of the respective guide rail. The marking areas of the respective scale body 15 were provided according to the example shown in FIG. 3B. In this case, the parameters D and ΔX were selected such that D=8 μm and ΔX=5 μm. In this case, the first track SP1 of the respective scale body 15 was realized such that the respective marking areas M and the respective mirror areas S of the scale body 15 each had one dimension of approximately 100 μm in the longitudinal direction of this scale body 15.

[0154] To form the displacement measuring system 10 shown in FIG. 1, each individual one of the scale bodies 15 thus provided on the sides 2.1 of the different guide rails was subsequently combined with the sensor device 20 shown in FIG. 1.

[0155] In order to characterize each individual scale body 15 of the plurality of scale bodies 15 thus provided on the sides 2.1 of the different guide rails, each individual scale body 15 of the scale bodies 15 was optically scanned by the sensor device 20. In this case, the sensor device 20 was moved in the longitudinal direction of the respective scale body 15 (as shown in FIG. 1 ), while the respective scale body 15 was illuminated by a light beam 22.1 emitted by the light source 22, and light RL1 reflected by the respective mirror areas of the first track SP1 was detected by the light sensors of the first array 25.1 of electronic light sensor chips 25.

[0156] In this case, the first array of light sensors 25.1 is configured such that the light sensors of the first array of light sensors 25.1 generate an output signal upon movement of the sensor arrangement 20 in the longitudinal direction of the scale body 15, which output signal varies periodically between a maximum signal value Smax and a minimum signal value Smin as a function of the position of the sensor arrangement 20 relative to the longitudinal direction of the scale body 15 with a periodic change corresponding to a mathematical sine or cosine progression. In order to characterize this periodic change of a respective output signal of one of the light sensors of the first array of light sensors 25.1, it is useful to determine a "signal contrast" K of a respective output signal of one of the light sensors of the first array of light sensors 25.1. This signal contrast K can in this connection be defined as the ratio consisting of the "amplitude" (Smax-Smin) / 2 of the change of the respective output signal as a function of the position of the sensor arrangement 20 relative to the longitudinal direction of the scale body 15 and the difference between the "average value" (i.e. (Smax+Smin) / 2) of the respective output signal and the "reference output signal" S0 of the respective optical sensor, i.e. the output signal of the respective optical sensor measured under conditions in which the light source 22 is switched off and thus does not form a light beam for illuminating the scale body 15. In other words, the signal contrast K of the respective output signal of one of the optical sensors of the first array 25.1 is: K=(Smax-Smin) / (Smax+Smin-2*S0). It is calculated as:

[0157] In general, the signal contrast K takes a value between 0 and 1.

[0158] The roughness of the side surface 2.1 of the guide rail 2 before forming the scale body 15 on the side surface 2.1 according to the described method clearly has a significant effect on the magnitude of the above-mentioned "signal contrast" K of each output signal of one of the optical sensors of the first array 25.1 of optical sensors of the sensor device 20.

[0159] When the scale body 15 is formed according to the described method on a side 2.1 of a guide rail 2 that has been ground in accordance with standards before forming the scale body 15 but has not been polished (after grinding in accordance with said standards), the sensor output signals of each of the optical sensors of the first array 25.1 of optical sensors of the sensor device 20 show a signal contrast K=0.29 when optically scanning the first track SP1 of the scale body 15.

[0160] When the scale body 15 is formed according to the described method on a side 2.1 of a guide rail 2 which has first been ground in accordance with a standard before forming the respective scale body 15 and subsequently (after grinding in accordance with the standard) further polished, the respective optical sensor output signals of the optical sensors of the first array 25.1 of optical sensors of the sensor device 20 show a respective signal contrast K in the range of 0.5 to 0.65 during optical scanning of the first track SP1 of the respective scale body 15 (this depends on the respective method used to polish the side 2.1 of the respective guide rail 2 and therefore on the degree of reduction in roughness obtained by the polishing process of the respective side 2.1 of the respective scale body 15 formed in accordance with the described method).

[0161] Thus, by polishing the side surface 2.1 before forming the respective scale body 15, the signal contrast K of the output signals of the optical sensors of the first array 25.1 of optical sensors of the sensor arrangement 20 can be significantly increased during optical scanning of the first track SP1 of the respective scale body 15. The respective magnitude of said signal contrast K is important for the measurement accuracy of the displacement measuring system 10 shown in FIG. 1 or the linear encoder 11 shown in FIG. 1: the greater the signal contrast K, the greater the accuracy. By evaluating the output signals of the optical sensors of the first array 25.1 of optical sensors of the sensor arrangement 20, the respective position of the sensor arrangement 20 in the longitudinal direction of the respective scale body 15 can be calculated with said accuracy.

[0162] As explained, in the above embodiment of the scale body 15, it is proposed that the individual marking areas of the scale body 15 are provided on the side surface 2.1 in such a way that all partial areas of the respective marking area M illuminated by an individual light pulse have respective overlaps UX and UY in two dimensions (i.e. in the longitudinal direction of at least one track and in a direction perpendicular to the longitudinal direction of said at least one track). The respective overlaps UX and UY between different illuminated partial areas affect the reflectivity of the respective marking area M compared to the reflectivity of the respective mirror area S. The reflectivity of the respective marking area M can be minimized in particular by appropriately selecting the size of the respective overlaps UX and UY. This makes it possible to improve the respective signal contrast K of the output signals of the optical sensors of the first array 25.1 of optical sensors of the sensor arrangement 20 during optical scanning of the first track SP1 of the respective scale body 15.

[0163] To characterize the effect of the magnitude of the overlap of the different illuminated sub-areas of the marking area M, for example, the effect of the magnitude of the overlap UX on the reflectance of the respective marking area M was evaluated.

[0164] For this purpose, using the method of the invention, three example regions (hereinafter "example region 1", "example region 2" and "example region 3") were produced side by side on the side surface 2.1 for the first track SP1 of a scale body 15 of the type shown in Figure 2. In this case, the side surface 2.1 was polished uniformly over all areas of said side surface before providing the marking regions M of the different first tracks SP1.

[0165] Here, the laser beam has a circular profile and was applied to the side surface 2.1 such that each light pulse of the laser beam illuminates a partial area at this side surface 2.1. The marking areas of the respective scale body 15 were provided according to the example shown in FIG. 3B. The parameters D and ΔY were selected such that D=15.2 μm and ΔY=5 μm. In this case, the first track SP1 of the respective scale body 15 was realized such that the respective marking areas M and the respective mirror areas S of the scale body 15 each have a dimension of approximately 100 μm in the longitudinal direction of the scale body 15.

[0166] Therefore, the distance ΔY is equal in the embodiments of the first track SP1 according to the above-mentioned region example 1, region example 2, and region example 3. This distance ΔY substantially determines the dimension DUY of the overlap portion UY irradiated by the laser pulse in the direction perpendicular to the X-axis direction or perpendicular to the longitudinal direction of the first track SP1 (DUY=D-ΔY=10.2 μm in this example).

[0167] The distance ΔY of the first track SP1 according to the above-mentioned embodiment of region example 1, region example 2 and region example 3 is different. This distance ΔX substantially determines the dimension DUX of the overlapping portion UX in the X-axis direction or longitudinal direction of the first track SP1. In this case, ΔX was selected as follows: for region 1 ΔX=5 μm; for region 2 ΔX=8 μm; for region 3 ΔX=15.2 μm.

[0168] The first track SP1 according to the above-mentioned embodiments of area example 1, area example 2 and area example 3 was scanned by the above-mentioned sensor arrangement 20, and for each of these embodiments, the output signal of each of the optical sensors of the first array 25.1 of optical sensors of the sensor arrangement 20 was measured during optical scanning of the first track SP1 of the scale body 15. In this case, the signal contrast K of each of the output signals of one optical sensor of the first array 25.1 of optical sensors of the sensor arrangement 20 was calculated for each of the above-mentioned embodiments of the first track SP1 according to area example 1, area example 2 and area example 3.

[0169] Table 1 below shows calculated values ​​for the signal contrast K, distance ΔX and dimension DUX of the overlap portion UX in the X-axis direction or longitudinal direction of the first track SP1 for each embodiment of the first track SP1 according to the above-mentioned region example 1, region example 2 and region example 3. [Table 1]

[0170] As can be seen from Table 1, in the case of area example 3, the different partial areas irradiated by laser pulses are distributed in the marking area M such that the different partial areas have no overlapping portion UX in the longitudinal direction of the first track SP1 (i.e. DUX=0), whereas in the case of area example 1 and area example 2, there is one overlapping portion UX each (where DUX>0).

[0171] As can be seen from Table 1, the signal contrast K for the example regions 1 and 2 is each greater than the corresponding value for the signal contrast K for the example region 3. Thus, in comparison with the example region 3 (where DUX=0), an increase in the dimension DUX of the longitudinal overlap portion UX of the first track SP1 improves the signal contrast K and therefore reduces the reflectivity of the marking region M.

[0172] It is noted that for forming the scale body 15 on the surface of the guide rail according to the invention, instead of the above-mentioned short-pulse laser, it is also conceivable to use an ultrashort-pulse laser having a pulse duration in the picosecond range, for example less than 10 picoseconds. The use of such an ultrashort-pulse laser allows the formation of a scale body with a reduced thermal load on the surface area illuminated by the light pulse. This has the advantage that the above-mentioned methods for cleaning and passivation after the formation of the scale body can be omitted.

[0173] It is noted in connection with Fig. 1 that the guide rail 2 - seen from the second side 2.2 - comprises at least one, in particular a number of blind holes, in particular with an internal thread. In this case, the first side 2.1 of the guide rail 2 can in particular be formed without a hole. The latter makes it possible to fasten the guide rail 2 to any structure by means of the blind holes mentioned above (not shown in Fig. 1). In this case, the entire surface of the first side 2.1 is provided exclusively for forming the scale body.

Claims

1. A method for forming a scale body (15) on the surface of a guide rail (2) of a linear profile rail guide (1), wherein the guide rail (2) has a first side surface (2.1) and an opposing second side surface (2.2), the scale body (15) includes at least one linear track (SP1, SP2) extending in the longitudinal direction (X) of the guide rail (2), having a plurality of mirror regions (S; S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, S13, S14, S15) and a plurality of marking regions (M1, M2, M3, M4, M5, M6, M7, M8, M9, M10, M11, M12, M13, M14) arranged alternately back and forth, each of the marking regions extends linearly in a direction transverse to the longitudinal direction (X) of the at least one track (SP1, SP2), the method comprising - a method step of providing a pulsed laser for forming a laser beam, - a method step of providing at least one of the marking regions (M1, M2, M3, M4, M5, M6, M7, M8, M9, M10, M11, M12, M13, M14) by forming a fine pattern in a first region (B1) of the first side surface (2.1) of the guide rail (2) corresponding to at least one marking region, wherein the laser forms a laser beam having a plurality of consecutive optical pulses, the laser beam is directed towards the first region (B1, B2) of the side surface (2.1), only one partial region (TB11, TB15, TB16, TB1n, TB21, TB25, TB26, TB2n) of the first region (B1) is irradiated by each individual optical pulse of the formed consecutive optical pulses consisting of a plurality of optical pulses The first side (2.1) has a spatial modulation that varies over the sub-regions (TB11, TB15, TB16, TB1n, TB21, TB25, TB26, TB2n) of the first region (B1) irradiated by the respective individual optical pulses of the first region, due to irradiation by the respective individual optical pulses, such that after irradiation by the respective individual optical pulses, the spatial modulation of the first side (2.1) extends over the sub-regions (TB11, TB15, TB16, TB1n, TB21, TB25, TB26, TB2n) of the first region (B1) irradiated by the respective individual optical pulses of the first region. The spatial dimension (D) of the sub-region irradiated by each individual optical pulse of the first region (B1) in the longitudinal direction (X) of the at least one track is smaller than the spatial dimension (DBX) of the first region (B1) in the longitudinal direction (X) of the at least one track (SP1, SP2), and the spatial dimension (D) of the sub-region irradiated by each individual optical pulse in the lateral direction with respect to the longitudinal direction (X) of the at least one track (SP1, SP2) is smaller than the spatial dimension (DBY) of the first region (B1) in the lateral direction with respect to the longitudinal direction (X) of the at least one track (SP1, SP2). The laser beam is moved relative to the guide rail (2) such that at least a plurality of the formed consecutive optical pulses irradiate, in a temporally continuous manner, a plurality of different sub-regions (TB11, TB15, TB16, TB1n, TB21, TB25, TB26, TB2n) of the first region that are spatially dispersed from each other. For each individual sub-region (TB15) of the plurality of different irradiated sub-regions, there are at least two other sub-regions (TB16) among the plurality of different irradiated sub-regions. The two other sub-regions are spatially shifted with respect to each individual sub-region (TB15) of the plurality of different irradiated sub-regions such that one sub-region (TB25) of the at least two other sub-regions among the plurality of different irradiated sub-regions is shifted in the longitudinal direction (X) of the at least one track (SP1, SP2) with respect to each individual sub-region (TB15) of the plurality of different irradiated sub-regions. As a result, one of the at least two different sub-regions (TB25) of the plurality of different sub-regions irradiated has an overlapping portion (UX) with each individual sub-region (TB15) of the plurality of different sub-regions irradiated, One of the at least two different sub-regions (TB16) of the plurality of different sub-regions irradiated is shifted laterally with respect to the longitudinal direction (X) of the at least one track (SP1, SP2) with respect to each individual sub-region (TB15) of the plurality of different sub-regions irradiated, As a result, one of the at least two different sub-regions (TB16) of the plurality of different sub-regions irradiated has an overlapping portion (UY) with each individual sub-region (TB15) of the plurality of different sub-regions irradiated, The plurality of different sub-regions irradiated together form a region congruent with the first region (B1) on the first side surface (2.1), the method.

2. The method is - A method step of surface-treating at least the first side surface of the guide rail so that a particularly small amount of material is removed from the first side surface of the guide rail before forming the fine pattern on the first side surface (2.1) of the guide rail by a pulsed laser beam, - The method according to claim 1, further comprising a method step of surface-cleaning at least the first side surface of the guide rail after forming the fine pattern on the first side surface by the laser beam.

3. The overlapping portion (UX) between each individual sub-region (TB11, TB1n) of the plurality of different sub-regions irradiated and at least one different sub-region (TB21, TB2n) of the plurality of different sub-regions irradiated has a spatial dimension (DUX) corresponding to 20 to 50% of the spatial dimension (D) in the longitudinal direction (X) of the at least one track (SP1, SP2) of the sub-region irradiated by each individual light pulse of the first region in the longitudinal direction (X) of the at least one track (SP1, SP2), and / or Of each individual partial region (TB15) among the plurality of different partial regions irradiated and at least one other partial region (TB16) among the plurality of different partial regions irradiated, an overlapping portion (UY) has a spatial dimension (DUY) corresponding to 20 to 50% of a spatial dimension (D) in a direction transverse to the longitudinal direction (X) of the at least one track (SP1, SP2) of the partial regions irradiated by respective individual light pulses in the first region. The method according to claim 1 or 2.

4. The laser is configured as a short-pulse laser for forming a light beam pulsed by light pulses having a pulse duration of less than 15 nanoseconds, or as an ultrashort-pulse laser for forming a light beam pulsed by light pulses having a pulse duration of less than 20 picoseconds, and / or The pulse parameters of the laser and / or the laser focus are selected such that when forming the fine pattern on the first side surface (2.1) of the guide rail (2) without removing the material or substantially without removing the material along the surface path, a material roughness is formed in the nanometer range. The method according to claim 1 or 2.

5. Before forming the fine pattern on the first side surface (2.1) of the guide rail (2) by a pulsed laser beam, at least the first side surface of the guide rail is surface-treated by a polishing process, and / or Before forming the fine pattern on the first side surface of the guide rail (2) by a pulsed laser beam, the first side surface (2.1) of the guide rail (2) has an average roughness value (Ra) of at most 0.3 μm, in particular at most 0.1 μm, and more preferably an average roughness value (Ra) in the range of about 0.007 μm to 0.1 μm. The method according to claim 1 or 2, wherein at least the first side surface (2.1) of the guide rail (2) is surface-treated.

6. Before forming the fine pattern on the first side surface (2.1) of the guide rail (2) by a pulsed laser beam, at least the first side surface of the guide rail is surface-treated by a polishing disk, by a laser polishing process, and / or by an electronic polishing process. The method according to claim 1 or 2.

7. After forming the fine pattern on the first side surface (2.1) of the guide rail (2), the first side surface (2.1) of the guide rail (2) is within one of the marking regions (M; M1, M2, M3, M4, M5, M6, M7, M8, M9, M10, M11, M12, M13, M14) of the marking region of the scale body (15), and has an average roughness value (Ra) that is 10 times greater than the average roughness value of the first side surface (2.1) within one of the mirror regions (S; S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, S13, S14, S15) of the mirror region of the scale body (15). The method according to claim 1 or 2.

8. After forming the fine pattern on the first side surface (2.1) of the guide rail (2) by the laser beam, the first side surface (2.1) of the guide rail (2) is surface cleaned, The surface cleaning is laser treatment and / or vibration cleaning or the application of ultrasonic waves to the first side surface. The method according to claim 1 or 2.

9. The laser beam has a substantially circular beam bundle, and is selected such that the beam bundle has a diameter of 3.5 μm to 12 μm, particularly 6 μm to 9 μm, and in particular about 8 μm, on the first side surface of the guide rail, and / or The laser is operated at a pulse frequency of about 60 kHz. The method according to claim 1 or 2.

10. A scale body (15) for a linear encoder (11) including a guide rail (2) of a linear profile rail guide (1), wherein the guide rail (2) has a first side surface (2.1) and an opposing second side surface (2.2), The scale body (15) includes at least one track (SP1, SP2) extending in the longitudinal direction (X) of the guide rail (2), having a plurality of mirror regions (S; S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, S13, S14, S15) and a plurality of marking regions (M; M1, M2, M3, M4, M5, M6, M7, M8, M9, M10, M11, M12, M13, M14) arranged alternately in the front and back. Each marking region (M; M1, M2, M3, M4, M5, M6, M7, M8, M9, M10, M11, M12, M13, M14) extends linearly in a direction transverse to the longitudinal direction of the at least one track (SP1, SP2), and is configured to absorb incident light and / or scatter and reflect the incident light. The mirror region (S; S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, S13, S14, S15) has at least a substantially smooth surface configured to mirror-reflect incident light, in the scale body (15). The scale body (15) is characterized in that it is formed on the first side surface (2.1) of the guide rail (2) according to the method according to claim 1 or 2.

11. The guide rail (2) includes at least one, particularly a plurality of bottomed holes, particularly having internal threads, as viewed from the second side surface (2.2). The scale body (15) according to claim 10, wherein the first side surface (2.1) of the guide rail (2) is provided particularly without holes.

12. The at least one track (SP1) is configured as an incremental track having a plurality of marking regions (M) arranged at equal intervals, or The scale body (15) according to claim 10, wherein the at least one track (SP2) is configured as a reference track having at least one marking region (M1, M2, M3, M4, M5, M6, M7, M8, M9, M10, M11, M12, M13, M14) for encoding at least one reference position.

13. - The scale body (15) according to claim 10, - At least one sensor device (20) configured to optically scan at least one track (SP1, SP2) of the scale body (15), a linear encoder (11) having The at least one sensor device (20) includes a measuring head (21) movable relative to the scale body (15), and the measuring head (21) A light source (22) for irradiating light (22.1) onto the mirror regions (S; S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, S13, S14, S15) and the marking regions (M; M1, M2, M3, M4, M5, M6, M7, M8, M9, M10, M11, M12, M13, M14) of the scale body (15); At least one array comprising an optical sensor configured to detect the light (RL1, RL2) irradiated from the light source (22) and reflected by the mirror regions (S; S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, S13, S14, S15) of the scale body (15). The linear encoder (11) having the same.

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