DE202017107880U1 - Linear displacement measuring device for determining an absolute position and linear guidance with such a distance measuring device - Google Patents

Abstract

A linear path measuring device (10) for determining an absolute position, comprising:
a) a linear rail (30) which has a longitudinal axis (31) and is composed of a plurality of individual rail segments (30a, 30b), which rail segments are arranged one behind the other in the direction of the longitudinal axis (31),
wherein each of the rail segments (30a, 30b) has a dimensional representation (40a, 40b) which comprises at least one first incremental track (41.1) extending in the direction of the longitudinal axis (31) with a plurality of equidistantly arranged position markings, and wherein the dimensional standard (40a ) of one of the rail segments (30a) next to the first incremental track (41.1) of this scale (40a) an absolute track (45) with a plurality of position markings for encoding a plurality of predetermined absolute positions, which lie in the direction of the longitudinal axis (31) one behind the other;
b) a scanning device (50) having a sensor arrangement (51) for scanning the dimensional standards (40a, 40b), which sensor arrangement comprises at least one first sensor (51.1), a second sensor (51.2) and a third sensor (51.3),
wherein the scanning device (50) is guided with respect to the rail (30) such that it is movable in the direction of the longitudinal axis (31) along a plurality of the rail segments (30a, 30b), and
wherein the first sensor (51.1) is designed to detect at least one position marking of the first incremental track (41.1) of one of the rail segments (30a, 30b) and to generate a first signal (S1) which contains information about a position of the scanning device (50). relative to the at least one position marker detected by the first sensor (51.1),
wherein the second sensor (51.2) is designed to detect at least one position marking of the first incremental track (41.1) of one of the rail segments (30a, 30b) and to generate a second signal (S2), which contains information about a position of the scanning device (50) relative to the at least one position marking detected by the second sensor (51.2),
wherein the first sensor (51.1) and the second sensor (51.2) are offset in the direction of the longitudinal axis (31) relative to one another by a predetermined distance (D), so that the scanning device (50) with respect to each two adjacent rail segments (30a, 30b) in a position (P1) can be brought, in which the first sensor (51.1) detects at least one of the position markings of the first incremental track (41.1) of the dimensional scale (40a) of the one of the two adjacent rail segments (30a) and the second sensor (51.2) at least detects one of the position markings of the first incremental track (41.1) of the scale (40b) of the other of the two adjacent rail segments (30b),
wherein the third sensor (51.3) is adapted to scan the absolute track (45) of the scale (40a) of the one of the rail segments (30a) and to generate a third signal (S3) containing information about a position of the scanner (50) relative to to the given absolute positions;
c) a first evaluation device (60) for the third signal (S3), which is designed to detect whether the scanning device (50) is located at one of the predetermined absolute positions with respect to the one of the rail segments (30a), and - if an evaluation of the third signal (S3) shows that the scanning device (50) at a first time at one of the predetermined absolute positions (P1) with respect to the one of the rail segments (30a) - to determine a first absolute value (AW1), which one the predetermined absolute positions (P1) represents;
d) a second evaluation device (65) for the first signal (S1) and the second signal (S2), which is formed after the first time the first signal and the second signal during a first time interval between the first time and a second time and a position difference (PD) between the position (P1) of the scanning device (50) at the beginning of the first time interval and a Determine position (P2) of the scanner (50) at the second time at the end of the first time interval;
e) a computing unit (70), which is designed to calculate from the first absolute value (AW1) and the position difference (PD) determined by the second evaluation device (65) a second absolute value (AW2), which determines an absolute position of the scanning device (50 ) at the second time at the end of the first time interval.

Description

Technical area

The invention relates to a linear position measuring device for determining an absolute position and a linear guide in combination with a linear position measuring device for determining an absolute position.

State of the art

Numerous known applications in various fields of technology are based on linear guides, which serve to guide at least one movable body in a linear movement in one direction, and which for this purpose usually have a linear rail on which the movable body is guided in such a way is that it can perform a linear movement in the direction of the longitudinal axis of the rail. The lengths of rails, which are to be manufactured in one piece and suitable for linear guides are usually limited for manufacturing reasons: With known manufacturing techniques usually only linear rails with the required precision in one piece can be produced, the lengths of a certain maximum (if applicable, depending on the respective manufacturing process) upper limit.

In order to allow a linear guidance of a movable body over an "arbitrarily" long distance, linear guides have been proposed, which have a linear rail for guiding the movable body, which is composed of a plurality of individual rail segments, each made in one piece and in the direction of Longitudinal axis of the linear rail are arranged one behind the other. Since the number of rail segments, which can be arranged one behind the other in a given direction, is not limited, it seems basically possible to assemble a sufficiently large number of integral rail segments with predetermined (finite) lengths to form a linear rail of any size Length may have.

In many known linear guide applications, there is an interest in metrologically sensing the current position of a movable body relative to the linear rail on which the movable body is guided, the current position of the movable body or a change in the position of the movable body be able to control as precisely as possible with a movement of the body in the longitudinal direction of the rail on the basis of measured values. Accordingly, suitable linear Wegmessvorrichtungen have been proposed, which allow a metrological detection of a current position of the movable body or a metrological detection of a change in the position of the movable body during movement of the body in the longitudinal direction of the rail.

Linear displacement measuring devices generally comprise one or more dimensional standards, each of which has a plurality of position markings, and a scanning device movable along the physical scale or the physical dimensions with a sensor arrangement for scanning the position markings of the respective dimensional scale or dimensional scale. In this case, the sensor arrangement is generally designed so that it can detect the respective position markings and generates at least one signal which contains information about a position of the sensor arrangement relative to the position markings of a dimensional standard and in particular varies in a characteristic manner when the scanning device together is moved with the sensor arrangement relative to the material measure or to the position markings of the scale.

In the case of a linear guide, which has a linear rail for guiding a movable body, to allow a metrological detection of a current position of the movable body or a metrological detection of a change in the position of the movable body during a movement of the body in the longitudinal direction of the rail For example, the linear guide can be combined with a linear displacement measuring device of the aforementioned type. For example, the linear rail of the linear guide can be provided with at least one dimensional scale, preferably with a dimensional scale which extends in the longitudinal direction of the linear rail and whose position markings are arranged one behind the other along the longitudinal axis of the linear rail. Accordingly, the scanning device of the linear displacement measuring device can be attached to the movable body such that the scanning device is moved along the linear rail with the movable body during a movement of the movable body and the scanning device can scan the position markings by means of the sensor arrangement.

In a linear guide whose linear rail is composed of several individual rail segments, it is expedient to provide each of the rail segments with at least one dimensional scale of the aforementioned type. The respective dimensions of the individual rail segments are preferably to be arranged such that position markings of all dimensions can be scanned by means of the sensor arrangement of the scanning device, if the movable body is moved along the individual rail segments.

In known linear displacement measuring devices, scale measurements are generally used which have either an incremental coding of different positions or a coding of different absolute positions (also called "absolute coding"). Also known are dimensional embodiments which include an incremental coding of different positions and additionally an absolute coding of individual positions (so-called "reference positions").

As a rule, a material measure with an incremental coding has an incremental track extending in a longitudinal direction of the material measure with a plurality of equidistantly arranged position markings. If the position markings of such an incremental track are scanned with a sensor arrangement of a scanning device moved in the longitudinal direction of the incremental track, then the sensor arrangement generally generates a signal which shows a periodic variation as a function of a location coordinate which characterizes the position of the sensor arrangement and accordingly in a Movement of the scanning device in the longitudinal direction of the incremental track changed. The periodic variation of the signal as a function of the spatial coordinate in a movement of the scanning device in the longitudinal direction of the incremental track in this case is due to the fact that position markings are formed at positions which are arranged at equal intervals (equidistant) in a row behind one another. An evaluation of the signal accordingly enables a precise detection of a relative change in the position of the scanning device during a movement of the scanning device in the longitudinal direction of the incremental track. However, information about a certain absolute position with respect to the scale does not provide this signal.

A material measure with an absolute coding generally has an absolute track with a plurality of position markings for coding a plurality of predefined absolute positions, which lie one behind the other in the longitudinal direction of the absolute track. The position markings of the absolute track each identify certain absolute positions with respect to the dimensional scale and are designed such that when scanning the position markings by means of the Abtsteinrichtung a signal is generated which contains information about the absolute positions, which are assigned to each scanned position markings.

In the publication US 7432497 B2 there is disclosed a linear path measuring device for determining an absolute position comprising a plurality of scales arranged in a row one after another and each having an absolute track extending over the entire length of the respective scale having a plurality of position markers for encoding a plurality of absolute positions , With regard to the structure of the absolute track, in particular with regard to the arrangement of the respective position markings for coding absolute positions on the respective absolute track, the individual scale bars are absolutely identical. The position markings contained in the absolute track of a single scale are therefore only suitable for encoding absolute positions with respect to this individual scale. In order to be able to code a plurality of absolute positions over the entire longitudinal extension of all scales, each scale additionally has a scale coding arranged next to the respective absolute track, which clearly identifies each scale and differentiates it from the other scales. Furthermore, there is a scanning device which is movable in the longitudinal direction of the scale bars and comprises a sensor arrangement with three or more sensors for scanning the absolute tracks and the scale codes. A first and a second sensor of the sensor arrangement of the scanning device are intended for scanning the absolute tracks, wherein the first and the second sensor with respect to the longitudinal direction of the scale bars are arranged at a predetermined distance relative to each other and the scales are arranged such that the distance of two each successive scales is less than the predetermined distance between the first and the second sensor. In this way, it is ensured that - at least when the scanning device is placed in a transition region between two adjacent scales - the absolute tracks of two adjacent scales are scanned by the first and second sensors and by means of the first sensor with respect to an absolute position one of the two adjacent scale bars and by means of the second sensor an absolute position with respect to the other of the two adjacent scale bars can be determined. Furthermore, the sensor arrangement comprises at least one third sensor for scanning the respective scale coding of a scale. In order to be able to determine an absolute position with respect to the entire arrangement of all scales, the distance measuring device comprises a computing unit which evaluates measurement signals which are generated by the first and the second sensor when scanning the absolute tracks or by the third sensor when scanning the scale codes and calculated from these measurement signals the absolute position with respect to the entire arrangement of all scales. This path measuring device has the Disadvantage that all scales must be designed differently so that each scale is different from all other scales (at least by the respective scale codes). For the realization of the measuring system may therefore be provided a large number of different scales. If one of the scales in the operation of the distance measuring device should be unusable and would have to be replaced by another scale, it results as a further disadvantage that the unusable scale can only be replaced by another scale, which differs from all other scales, which is the selection of the other scale limits.

Since the different scales of the Wegmessvorrichtung can be mounted in an installation usually only with certain tolerances in terms of their position, each have two adjacent (in the longitudinal direction of the scales immediately behind one another) scales after installation in the longitudinal direction of the scales a certain distance, which initially not known exactly. Accordingly, the two absolute tracks, which are formed on two adjacent (in the longitudinal direction of the scales immediately one behind the other arranged) scales, in the longitudinal direction of the scales on a certain distance, which is also not known exactly first.

In order to be able to determine an absolute position with respect to the entire arrangement of all scales, it is therefore necessary, when the path measuring device is put into operation for the first time, to cause the scanning device to perform an "initialization run" along the entire arrangement of all scales in the longitudinal direction of the scales. During such an initialization run of the scanning device, the respective absolute tracks are scanned simultaneously by comparing the measurement signals generated by the first sensor and the second sensor, the respective distances between two absolute tracks, which at two adjacent (in the longitudinal direction of the scales directly arranged one behind the other) are formed scales calculated. These calculated distances between each two adjacent absolute tracks are stored in a data memory. Following this initialization of the Abtasttasteinrichtung the arithmetic unit of the path measuring device is finally able, from the measurement signals generated by the first, second and third sensor and the data stored in the memory between each two adjacent absolute tracks respectively the instantaneous absolute position of the Abtasttasteinrichtung with respect to to calculate the total arrangement of all scales.

If one of the scales in the operation of the distance measuring device should be unusable and would have to be replaced by another scale, there is the further disadvantage that after replacing the unusable scale by another scale again an initialization of the Abtasttasteinrichtung in the longitudinal direction of the scales (at least over a portion of the scales) and the position marks of the respective scales must be scanned repeatedly by the scanner so that the distances between any two adjacent absolute tracks can be re-acquired and stored in the data memory even after the unusable scale has been replaced on the basis of updated measurements ,

From the publication EP 2 533 018 A1 For example, a linear displacement measuring system is known for determining a position of a carriage in relation to a track rail composed of a plurality of individual rails. Each of the individual rails is provided with a longitudinally extending scale comprising incremental position marks and / or absolute position marks. In this case, it is provided that all scales are identical in terms of the position markings and that the individual rails (each provided with a scale) can be provided as identical components. In order to distinguish different individual rails from each other, each individual rail can be provided with an individual coding. The individual coding of a single rail is in this case implemented by a plurality of sealing plugs which are inserted into respective bores of the single rail and close these bores, each sealing plug carrying discrete information representing the individual coding of the respective single rail. Furthermore, there is a scanner with sensors for sensing the position marks of the scales and the individual codes formed on the plugs. The holes into which the sealing plugs are to be inserted are generally through holes into which fastening means for fastening the respective individual rail to a base can be inserted. Accordingly, the respective sealing plug can be installed only after installation of the individual rails and must be removed again, if a single rail would have to be replaced (eg in the case of a defect). This has the disadvantage that after a commissioning of the displacement measuring system over time individual plugs can be removed undesirably and possibly lost or different plugs of users of the displacement encoder can be interchanged or incorrectly placed (eg in a wrong place, ie not in a bore associated with the respective individual coding formed on the respective sealing plug). The latter leads to errors in the determination of a position during operation of the position measuring system and consequently affects the functionality of the position measuring system.

Summary of the invention

The present invention has for its object to avoid the disadvantages mentioned and to provide a linear Wegmessvorrichtung for determining an absolute position with respect to a composed of several individual rail segments linear rail, which is easy installable and operable in operation and a simple exchange individual rail segments allows. Furthermore, a linear guide in combination with such a linear displacement measuring device for determining an absolute position to be proposed.

This object is achieved by a linear path measuring device for determining an absolute position with the features of claim 1 and a linear guide having the features of claim 11.

The linear path measuring device for determining an absolute position comprises a linear rail, which has a longitudinal axis and is composed of a plurality of individual rail segments, which rail segments are arranged one behind the other in the direction of the longitudinal axis, wherein each of the rail segments has a dimensional scale, which at least one in the direction of Having longitudinal axis extending first incremental track with a plurality of equidistantly arranged position markings, and wherein the scale of one of the rail segments next to the first incremental track of this scale an absolute track with a plurality of position markers for encoding a plurality of predetermined absolute positions, which lie in the direction of the longitudinal axis one behind the other ,

The linear path measuring device further comprises a scanning device with a sensor arrangement for scanning the dimensional standards, which sensor arrangement comprises at least a first sensor, a second sensor and a third sensor. The scanning device is guided with respect to the rail such that it is movable in the direction of the longitudinal axis along a plurality of rail segments, wherein the first sensor is designed to detect at least one position mark of the first incremental track of one of the rail segments and to generate a first signal which contains information includes a position of the scanner relative to the at least one position marker detected by the first sensor, and wherein the second sensor is configured to detect at least one position marker of the first incremental track of one of the rail segments and to generate a second signal indicative of a position the scanner includes relative to the at least one position marker detected by the second sensor. The first sensor and the second sensor are arranged offset relative to each other in the direction of the longitudinal axis by a predetermined distance, so that the scanning device with respect to each two adjacent rail segments can be brought into a position in which the first sensor at least one of the position marks of the first incremental track of the scale of the detects one of the two adjacent rail segments and the second sensor detects at least one of the position markings of the first incremental track of the dimensional scale of the other of the two adjacent rail segments. The third sensor is configured to scan the absolute track of the dimensional scale of the one of the rail segments and to generate a third signal which contains information about a position of the scanning device relative to the predetermined absolute positions.

The linear path measuring device further comprises a first evaluation device for the third signal, which is designed to detect whether the scanning device is located at one of the predetermined absolute positions with respect to the one of the rail segments, and - if an evaluation of the third signal shows that the scanning device at a first time at one of the predetermined absolute positions with respect to the one of the rail segments - to determine a first absolute value which represents one of the predetermined absolute positions.

The linear path measuring device also comprises a second evaluation device for the first signal and the second signal, which is designed to evaluate the first signal and the second signal during the first time interval between the first time and a second time and a position difference between the first time interval Detecting the position of the scanner at the beginning of the first time interval and a position of the scanner at the second time at the end of the first time interval.

In addition, there is an arithmetic unit which is designed to calculate from the first absolute value and the position difference determined by the second evaluation device a second absolute value which represents an absolute position of the scanning device at the second time at the end of the first time interval.

The linear displacement measuring device according to the invention is characterized in that each of the rail segments of the linear rail has a dimensional representation and the dimensional standards of all rail segments have an incremental track with a plurality of equidistantly arranged position markings, wherein only the dimensional scale of one of the rail segments additionally an absolute track with a plurality of position markings for coding a plurality of predetermined absolute positions, and wherein a scanning device movable in the longitudinal direction of the linear rail is provided with a sensor arrangement which enables a scanning of the position markings of the incremental tracks of the respective rail segments and of the position markings of the absolute track of the one of the rail segments. When commissioning the Wegmessvorrichtung, it is only necessary that the scanning device with respect to the one rail segment, which has the absolute track is brought into a position in which the third sensor of the scanning device (corresponding to the above "first absolute value") one of the predetermined absolute Detects positions which are coded on the one absolute track. The position at which the scanning device is located at the moment of detection of the one of the predetermined absolute positions relative to the one of the rail segments can thus be identified with the one of the absolute positions detected by the third sensor. Any movement of the scanning device that removes the scanning device in the longitudinal direction of the guide rail from the one of the absolute positions previously detected by the third sensor may then be registered and quantitatively characterized by scanning the incremental tracks of the respective rail segments using the first and second sensors , An evaluation of the first signal generated by the first sensor and the second signal generated by the second sensor in this case comprises in particular a registration of a change of the first signal or a change of the second signal and thereby allows a precise measurement of the position difference (ie the distance) between the position, at which the scanning device is currently located, and the one of the predetermined absolute positions, which was previously detected by the third sensor, and in particular any change of the first signal or any change of the second signal with a certain change in the position of the scanning device in the direction of the longitudinal axis corresponds. Finally, as a result of a calculation based on the measured position difference and the first absolute value for the one of the predetermined absolute positions previously detected by the third sensor, the arithmetic unit provides a "second absolute value" representing the position at which the Scanning device is currently located, with respect to the entire arrangement of all rail segments clearly identified and thus defines an absolute position of the scanner. After the detection of one of the predetermined absolute positions which are coded on the one absolute track, the arithmetic unit accordingly provides up-to-date information about an absolute position of the scanning device with respect to the entire arrangement of all rail segments. The absolute position calculated by the arithmetic unit is updated every time the scanning device moves in the longitudinal direction of the rail (corresponding to the respective current position). The scanning device can be moved to any position on any rail segment. In this way, any position which the scanning device can assume with respect to the entire arrangement of all rail segments is assigned a (unambiguous) absolute position, which can be calculated by means of the arithmetic unit.

This absolute position calculation assumes only that for any position that the scanner can occupy with respect to the entire arrangement of all rail segments, the position difference (ie, the distance) between that arbitrary position and the one of the predetermined absolute positions previously detected by the third sensor is measurable. The measurability of this position difference is basically ensured in the present case in that the first sensor and the second sensor are arranged offset relative to each other by a predetermined distance in the direction of the longitudinal axis, so that the scanning device can be brought into a position with respect to each two adjacent rail segments, in which the first sensor detects at least one of the position markings of the first incremental track of the dimensional scale of the one of the two adjacent rail segments, and the second sensor detects at least one of the position markings of the first incremental track of the dimensional scale of the other of the two adjacent rail segments. The latter ensures that, regardless of the position of the scanner, at least one of the sensors of the scanner (ie, the first sensor, the second sensor or both the first sensor and the second sensor) is placed with respect to the incremental tracks such that at each Timing at least one signal (ie, the first signal and / or the second signal) is generated, which is associated with a sampling of the position marks one of the incremental tracks and therefore at any time a measurement of a change in position of the scanning device in the longitudinal direction of the linear rail on the basis an evaluation of the first signal and / or the second signal allows.

The displacement measuring device has the advantage that all rail segments including the material present on the respective rail segment dimensional standard - with the exception of the rail segment, which has the absolute track - can be constructed completely identical and accordingly can be arranged in any order one behind the other to form the linear rail , This greatly simplifies the provision of all rail segments needed to construct the linear rail and also facilitates the assembly of all rail segments. The latter is particularly true when a rail segment is provided with a dimensional scale such that the rail segment together with the dimensional scale is present as a single body which can be transported as a whole and mounted at a predetermined location. Furthermore, the commissioning of the displacement measuring device is simplified in that at the beginning of commissioning only a single of the absolute positions must be detected, which are coded on the one absolute track on one of the rail segments. For any other position in which the scanning device is subsequently deviating from the already detected absolute position, an absolute position can then be calculated directly by the arithmetic unit (on the basis of a measurement of the position difference with respect to the already detected absolute position by means of a scan the incremental tracks). This absolute position calculation may be performed immediately after detecting a single one of the absolute positions coded on the one absolute track on one of the segments for any position on any rail segment to which the scanner can be brought. For this reason, any possible absolute position of the scanner immediately after detecting a single one of the absolute positions on the one absolute track on one of the rail segments can be determined without the scanner having previously initiated an initialization run over the entire length of the linear rails (ie along all rail segments). and must scan all position markings of all mass embodiments. In this way, a commissioning of the Wegmessvorrichtung can be advantageously carried out with relatively little effort, especially since an initialization of the aforementioned type is unnecessary.

An embodiment of the path measuring device is designed such that the scanning device, the first evaluation device, the second evaluation device and / or the arithmetic unit are operable by means of a supply of electrical energy and an electrical power supply device is provided, which is formed after the first time an uninterruptible supply of electrical energy to the scanning device, the first evaluation device, the second evaluation device and / or the computing unit to allow. The uninterruptible supply of electrical energy after the first time (ie after the time at which the scanner is at one of the predetermined absolute positions with respect to the one of the rail segments and has determined a first absolute value representing it one of the predetermined absolute positions) in that the scanning device, the first evaluation device and the second evaluation device are capable of registering a movement of the scanning device in the longitudinal direction of the linear rails after the first time and the respective positional difference between the instantaneous position of the scanning device at any second time after the first Time and position of the scanner to determine the first time. Accordingly, it is ensured that the arithmetic unit at the second time provides a "second absolute value" which represents the absolute position at which the scanner is located at the second time, regardless of which position the scanner moves after the first time, if any has been. Accordingly, it is ensured that during the uninterrupted supply of electrical energy, the arithmetic unit constantly provides up-to-date information about the absolute position of the scanning device with respect to the entirety of all rail segments (for example for a control device for controlling a machine, which are controlled as a function of the second absolute value should).

A further embodiment of the path measuring device is designed in such a way that the dimensional scale of at least one of the rail segments-with the exception of the one of the rail segments having the absolute track-comprises a second incremental track extending in the direction of the longitudinal axis in addition to the first incremental track of this at least one of the rail segments and a plurality of equidistantly arranged position markings, and the second incremental track is arranged relative to the third sensor of the scanning device such that the second incremental track can be scanned by the third sensor and the position markings of the second incremental track are detectable by means of the third sensor. The second incremental track offers the possibility of generating at least one additional measurement signal by scanning the (incremental) position markings of the second incremental track by means of the third sensor, which is particularly suitable for providing information which permits control of the position-measuring device, for example in terms of design Details of the rail segments and / or the functionality of the Wegmessvorrichtung. For example, the dimensional scale of a plurality of rail segments, and in particular the dimensions of all rail segments - with the exception of the one of the rail segments, which has the absolute track - comprise such a second incremental track.

In a variant of this embodiment, two adjacent position markings of the second incremental track are arranged at a distance which is greater than the distance between two adjacent position markings of the first incremental track. Alternatively or additionally, the third sensor may be configured to generate a fourth signal during scanning of the second incremental track, and the arithmetic unit may be configured to compare the fourth signal with the first signal and / or the second signal.

In the case of a movement of the scanning device in the longitudinal direction of the linear rail, it is to be expected that the first sensor, the second sensor or the third sensor respectively, when scanning the position markings of the first incremental track or when scanning the position markings of the second incremental track, signals which ideally ie as it is to be expected with correct operation of the position measuring device) each generate signals which vary periodically as a function of a location coordinate which characterizes the position of the sensor arrangement and accordingly changes upon movement of the scanning device in the longitudinal direction of the incremental track, all of these signals with each other are synchronized. If the signals generated by the respective sensors unexpectedly show a deviating behavior during operation of the displacement measuring device, this could indicate certain defects and / or irregularities, for example errors with regard to the design and / or installation of the displacement measuring device or irregularities in operation of the displacement measuring device (malfunctions).

If two adjacent position markings of the second incremental track are arranged at a distance which is greater than the distance between two adjacent position markings of the first incremental track, the first and the second sensor periodically generate a function when the scanning device moves in the longitudinal direction of the linear rail time-varying signals (ie, the first signal and the second signal, respectively) which vary at a greater frequency than a corresponding (periodically, as a function of time) varying signal (the fourth signal) which the third sensor generates when scanning the second incremental track , The signals generated by the first sensor and the second sensor are distinguishable in this case from the signal generated by the third sensor on the basis of the respective frequencies with which the signals vary as a function of time. The size of the distance, in each case two adjacent position markings of the second incremental track in the longitudinal direction of the linear rail are arranged one behind the other, can be chosen freely, for example, such that the respective size of this distance varies depending on characteristic parameters of the Wegmessvorrichtung and therefore as a Coding of the characteristic parameters is used. As "characteristic parameters of the Wegmessvorrichtung" come into consideration in this regard, for example: the "size" of the respective rail segment, characterized by the length, height and / or width of the rail segment; an identification of a particular embodiment of the Wegmessvorrichtung, if the Wegmessvorrichtung is feasible in various embodiments. An evaluation of the fourth signal, which can be generated by means of the third sensor when scanning the second incremental track, in this case provides information about the respective characteristic parameters of the position-measuring device. Such an evaluation of the fourth signal, for example, makes it possible to automatically check, by technical means, whether the position-measuring device is actually installed "correctly", i. is composed in particular of those components (for example, rail segments), which were originally intended for a specific installation of the Wegmessvorrichtung.

The third sensor is arranged such that it is suitable, depending on the respective position which the scanning device assumes with respect to the linear rail, alternatively the position markings of the one absolute track on the one of the rail segments or the position markings of the second incremental track on the other of the rail segments scan. The respective second incremental track can be distinguished from the absolute track at least in that the second incremental track and the absolute track have position markings which differ with regard to their spatial arrangement (the position markers of the absolute track are generally not arranged equidistantly, in contrast to the position markings of an incremental track). , An evaluation of the signals generated by the third sensor therefore makes it possible to carry out an automatic check by means of technical means whether the scanning device is currently arranged on the one rail segment having the absolute track or if the scanning device is arranged on another of the rail segments.

Another variant of the aforementioned embodiment is designed such in that the absolute track of the one of the rail segments comprises a first coding which contains information about at least one characteristic parameter of at least one of the other of the rail segments of the linear rail, and the first coding can be detected by means of the third sensor. In this case, the at least one characteristic parameter can be, for example, a size of at least one of the other of the rail segments or a distance between two adjacent position marks of the second incremental track. The first coding is placed in the absolute track so that it can be scanned by means of the third sensor (in the case of a corresponding arrangement of the scanning device relative to the absolute track). The third sensor is accordingly designed to generate a signal during scanning of the first coding, which signal can be evaluated, for example, by means of the first evaluation device in order to determine the at least one characteristic parameter of the aforementioned type. The same characteristic parameter associated with the first coding contained in the absolute track of one of the rail segments may also be encoded in the respective second incremental tracks of the other rail segments: As mentioned, the size of the spacing may be in each of two adjacent position marks of the second incremental track are arranged equidistantly one behind the other in the longitudinal direction of the linear rail, are selected such that the respective size of this distance as a coding of characteristic parameters of the Wegmessvorrichtung (eg as encoding the size of the respective rail segment, characterized by the length, height and / or width of the rail segment ) serves. Accordingly, the first encoding on the absolute track of one of the rail segments and the second incremental track of the respective other rail segments may be implemented such that the first encoding on the absolute track of one of the rail segments and the second incremental track respectively indicate whether the one rail segment comprising the rail Absolute track, and any other rail segment, which has the second incremental track, with respect to predetermined characteristic parameters of the Wegmessvorrichtung (eg, in terms of the size of the respective rail segments) are compatible with each other. In this case, an evaluation of the respective signals generated by the third sensor allows an automatically feasible by technical means control whether the linear rail of the Wegmessvorrichtung is composed exclusively of rail segments, which are compatible with each other with respect to predetermined characteristic parameters of the distance measuring device.

An embodiment of the path measuring device is designed such that the linear rail is composed of more than two of the rail segments and all rail segments - with the exception of the one of the rail segments, which has the absolute track - are identical. The term "identically formed" here comprises that the rail segments including the respective dimensions are identical. Using a plurality of identical rail segments simplifies the provision of the rail segments required for the installation of the path measuring device and the installation of the path measuring device with regard to the mounting of the rail segments. In particular, using a plurality of identical rail segments simplifies storage for the respective rail segments needed to build one or more path measuring devices and simplifies logistics in installing one or more path measuring devices.

For example, because of the use of a plurality of identical rail segments, this embodiment can advantageously be implemented in such a way that the rail segments can be mounted one behind the other in any order to form the linear rail. When mounting the rail segments in this case, no one must pay attention to a specific order of the rail segments to be mounted, which simplifies the implementation of the assembly, in particular with regard to a control of the rail segments to be mounted during assembly. This has the advantage that errors in the assembly of the rail segments can be easily avoided.

When the position measuring device is put into operation, it is essential that the scanning device is brought into a position with respect to the one rail segment having the absolute track in which the third sensor of the scanning device (corresponding to the abovementioned "first absolute value") detects one of the predetermined absolute positions , which are coded on the one absolute track. Thereafter, any movement of the scanning device that removes the scanning device in the longitudinal direction of the linear rail from the one of the absolute positions previously detected by the third sensor by registering the incremental tracks of the respective rail segments by means of the first and second sensors can be registered and quantitatively characterized so that the path measuring device is able to calculate a respective current absolute position of the scanning device. The sequence in which the individual rail segments are arranged one behind the other has no influence on the determination of the current absolute position of the scanning device and is therefore not relevant with regard to the determination of the respectively current absolute position of the scanning device.

Further, because of the use of multiple identical rail segments, this embodiment is advantageously implementable such that each of the rail segments, except for one of the rail segments having the absolute track, is interchangeable with an identical rail segment. Such an exchange of one of the rail segments could be expedient, for example, if one of the rail segments, which are identically formed, should prove to be defective after the start-up of the position measuring device, for example as a result of damage or as a result of wear. In this case, the rail segment to be replaced can be disassembled and replaced by another rail segment. The replacement of the one rail segment can be made during the operation of the Wegmessvorrichtung. In this case, it is expedient if the scanning device has been positioned with respect to the linear rail before the replacement of the one rail segment such that the sensors of the scanning device do not scan the position markings on the material measure which is formed on the rail segment to be exchanged. In this case, before exchanging the one rail segment, the arithmetic unit provides an absolute value which correctly characterizes the current absolute position of the scanning device. If the rail segment to be exchanged is then dismantled and replaced by another rail segment, then under the abovementioned circumstances this has no influence on the absolute value which the arithmetic unit provides, especially since the scanning device is not placed in this case in such a way that the sensors of the scanning device have the position markings can detect on the scale of the rail segment to be replaced. If the scanning device is moved again in the longitudinal direction of the linear rail after the replacement of one rail segment, this movement of the scanning device can be registered and quantitatively characterized by means of the first and the second sensor by scanning the position markings of the first incremental track of the dimensional examples of the respective rail segments, the path measuring device is able to correctly calculate the respective current absolute position of the scanning device. After replacing the one rail segment, the operation of the Wegmessvorrichtung can be continued accordingly simple. In order to enable a correct determination of the current absolute position, it is accordingly unnecessary to first place the scanning device after the replacement of the one rail segment such that one of the position markings of the one absolute track can be detected by means of the third sensor of the scanning device. Likewise, it is unnecessary for the scanning device, after the replacement of the one rail segment, to carry out an initialization run over the entire length of the linear rail (ie along all rail segments) and to scan all the position markings of all the mass embodiments. In this way, an exchange of a rail segment can advantageously be carried out with relatively little effort.

The invention also relates to a linear guide, which comprises a movable body and a linear displacement measuring device of the aforementioned type. The movable body is supported via rolling elements on the linear rail of the linear Wegmessvorrichtung, so that the rolling elements allow a guided linear movement of the movable body in the longitudinal direction of the linear rail, wherein the scanning device of the linear Wegmessvorrichtung is arranged on the movable body. The absolute position determined by the path measuring device in this case defines an absolute position of the movable body with respect to the linear rail, which is composed of a plurality of rail segments arranged one behind the other in the longitudinal direction of the rail.

list of figures

• 1 eine schematische Darstellung einer linearen Schiene, welche aus mehreren in Längsrichtung der linearen Schiene hintereinander angeordneten Schienensegmenten zusammengesetzt ist, wobei die Schienensegmente jeweils eine Massverkörperung mit Positionsmarkierungen aufweisen;
• 2 eine schematische Darstellung einer Abtasteinrichtung mit mehreren Sensoren zum Detektieren der Positionsmarkierungen der Massverkörperungen gemäss 1;
• 3 eine schematische Darstellung einer erfindungsgemässen Wegmessvorrichtung mit einer linearen Schiene gemäss 1 und einer Abtasteinrichtung gemäss 2;
• 4 eine schematische Darstellung einer erfindungsgemässen Linearführung zum Führen eines bewegbaren Körpers mit einer Wegmessvorrichtung gemäss 3.

Further details of the invention and in particular exemplary embodiments of the inventive linear displacement measuring device and the inventive linear guide will be explained below with reference to the accompanying drawings. Show it:

• 1 a schematic representation of a linear rail, which is composed of several in the longitudinal direction of the linear rail one behind the other arranged rail segments, wherein the rail segments each having a dimensional scale with position markings;
• 2 a schematic representation of a scanning device with a plurality of sensors for detecting the position markings of the scale embodiments according to 1 ;
• 3 a schematic representation of an inventive Wegmessvorrichtung with a linear rail according to 1 and a scanning device according to 2 ;
• 4 a schematic representation of an inventive linear guide for guiding a movable body with a Wegmessvorrichtung according 3 ,

Description of embodiments

Regarding 1-3 will first be an embodiment of a linear Displacement measuring device according to the invention explained. The 3 shows - in a schematic representation - an overall view of an inventive linear Wegmessvorrichtung 10 which is a linear rail composed of several individual rail segments 30 and one in the direction of a longitudinal axis 31 the linear rail 30 movable scanning device 50 for scanning dimensional standards. To clarify the present facts show 1 a separate schematic representation of the rail 30 and 2 a separate schematic representation of the scanner 50 ,

As 1 and 3 hint, is the rail 30 composed of two or more individual rail segments, which rail segments in the direction of the longitudinal axis 31 are arranged one behind the other, wherein the entirety of all rail segments in the present example, a first rail segment 30a and two second rail segments 30b having. Within the scope of the invention it would also be possible for the rail 30 only a second rail segment 30b or more than two second rail segments 30b having. The rail segments 30a respectively. 30b are preferably shaped so that they - around the rail 30 to form - in the direction of the longitudinal axis 31 can be mounted one behind the other such that in each case one end of one of the rail segments 30a respectively. 30b to one end of another (adjacent) rail segment 30a respectively. 30b pushes (like 1 and 3 hint). The latter implies that between abutting ends of two adjacent rail segments, a gap may be present to facilitate assembly and / or disassembly of the rail segments or to allow adjustment of individual rail segments relative to each other within predetermined tolerances when mounting the rail segments. The rail segments are fastened during assembly usually with suitable fasteners (eg screws) to a (not shown in the figures) supporting structure, which the rail 30 wears as a whole.

Each of the rail segments 30a . 30b has a dimensional embodiment. In order to be able to distinguish different realizations of physical dimensions, the material measure becomes the first rail segment 30a has, with the reference numeral below 40a denoted, and the dimensional scale, which the respective second rail segment 30b has, with the reference numeral below 40b designated.

As 1 and 3 suggest, includes each of the scale embodiments 40a respectively. 40b at least one in the direction of the longitudinal axis 31 the linear rail 30 extending first incremental track 41.1 with a plurality of equidistantly arranged position markings. The individual position markings of the respective first incremental track 41.1 are in 1 and 3 as straight, perpendicular to the longitudinal axis 31 aligned and identically shaped linear markings formed in the direction of the longitudinal axis 31 arranged one behind the other, so that they are in the direction of the longitudinal axis 31 extending periodic arrangement with a period length d1 (corresponding to the distance of two adjacent position markers of the incremental track).

In addition, the dimensional standard includes 40a of the first rail segment 30a next to the first incremental track 41.1 an absolute track 45 with a plurality of position markers for encoding a plurality of predetermined absolute positions which are in the direction of the longitudinal axis 31 lie one behind the other. The individual position markings of the absolute track 45 the dimensional embodiment 40a are in 1 and 3 as straight, perpendicular to the longitudinal axis 31 aligned and identically shaped linear markings shown in the direction of the longitudinal axis 31 are arranged one behind the other in that they - in contrast to the position markings of the respective incremental track 41.1 - do not form a periodic arrangement. In other words: the position markers of the absolute track 45 are along the longitudinal axis 31 arranged at irregular intervals one behind the other. Here, a particular group of a plurality of position markers, which encode a predetermined number of adjacent position markings (for example two, three, four or more position markings, which are in the direction of the longitudinal axis 31 arranged in direct succession) includes a predetermined absolute position with respect to the first rail segment 30a wherein the respective position markings of this group are arranged at intervals to each other, which is the one predetermined absolute position with respect to the first rail segment 30a clearly identify. By several predetermined absolute positions, which in the direction of the longitudinal axis 31 lie one behind the other, uniquely identify, contains the absolute track 45 the dimensional embodiment 40a a plurality of different sets of multiple position markers, each of which groups having a predetermined number of adjacent position markers (eg, two, three, four, or more position markers which are in the direction of the longitudinal axis 31 arranged one after the other) which respectively encode one of the predetermined absolute positions, so that different of these groups are respectively assigned to different predetermined absolute positions, the respective position markings of a certain group being at predetermined distances from each other which are the predetermined absolute position with respect to the first rail segment 30a uniquely identify which is assigned to the respective group. With regard to the present example according to 1 and 3 is assumed to be the absolute track 45 a number n ("n" here denotes any natural number with n> 1) of predetermined absolute positions AP1 to AP n which is preferably over the entire length of the rail segment 30a are arranged distributed. For the sake of simplicity, in 1 only two of these predetermined absolute positions, AP1 and AP n represented. As can be seen, the absolute positions AP1 and AP n in the present example opposite ends of the absolute track 45 associated with those position markings of the absolute track 45 , which codes of the absolute positions AP1 and AP n form, in 1 are not specifically identified.

The respective dimensional embodiments 40a and 40b are basically feasible on the basis of conventional technologies, which are suitable for providing position markings on the respective rail segments, which can be detected by means of sensors. The individual position markings of the incremental track 41.2 and the absolute track 45 For example, they may be formed as structures that can be detected by optical means (eg, optical sensors). Alternatively, the individual position markings of the incremental track 41.2 and the absolute track 45 For example, be formed as magnetic structures which are detectable with corresponding, sensitive to the magnetic structures means (for example, with sensors for measuring a magnetic field on the respective magnetic structure or sensors for measuring a magnetization in the respective magnetic structure).

How out 2 and 3 as can be seen, the scanning device comprises 50 a sensor arrangement 51 for scanning the dimensional standards 40a respectively. 40b , The sensor arrangement 51 includes at least a first sensor 51.1 , a second sensor 51.2 and a third sensor 51.3 , The scanning device 50 is regarding the rail 30 guided so that they are in the direction of the longitudinal axis 31 along several of the rail segments 30a respectively. 30b the rail 30 , preferably over the entire length of the rail 30 , is linearly movable. This mobility of the scanner 50 is in 3 by one with the reference numeral 21 provided double arrow indicated.

The first sensor 51.1 , the second sensor 51.2 and the third sensor 51.3 are arranged at intervals to each other in order to achieve that these sensors simultaneously different, spatially separated areas of the scale 40a respectively. 40b can scan. The sensors 51.1 . 51.2 and 51.3 For this purpose, they may be arranged spatially to one another, for example, at three separate points which form the three vertices of a triangle ( 2 and 3 ).

The sensors 51.1 and 51.2 are used to scan the first incremental track 41.1 of the measure embodiments 40a and 40b at the rail segments 30a and 30b , The first sensor 51.1 is in particular formed, at least one position marking of the first incremental track 41.1 one of the rail segments 30a respectively. 30b to detect (if the first sensor 51.1 is suitably positioned with respect to the position mark to be detected) and a first signal S1 which generates information about a position of the scanning device 50 relative to the at least one, from the first sensor 51.1 contains detected position mark. Furthermore, the second sensor 51.2 likewise formed, at least one position marking of the first incremental track 41.1 one of the rail segments 30a respectively. 30b to detect (if the second sensor 51.2 is suitably positioned with respect to the position mark to be detected) and a second signal S2 which generates information about a position of the scanning device 50 relative to the at least one of the second sensor 51.2 contains detected position mark.

How out 2 and 3 can be seen, are the first sensor 51.1 and the second sensor 51.2 in the direction of the longitudinal axis 31 arranged offset relative to each other by a predetermined distance D, so that the scanning device 50 with respect to each two adjacent rail segments, ie with respect to the first rail segment 30a and to the rail segment 30a adjacent second rail segment 30b or with respect to two adjacent rail segments 30b , Can be brought into a position in which the first sensor 51.1 at least one of the position marks of the first incremental track 41.1 the dimensional standard of one of the two adjacent rail segments detected and the second sensor 51.2 at least one of the position marks of the first incremental track 41.1 the dimensional standard of the other of the two adjacent rail segments detected.

Furthermore, the third sensor 51.3 trained, the absolute track 45 the dimensional embodiment 40a of a first rail segment 30a to sample and a third signal S3 which generates information about a position of the scanning device 50 relative to the predetermined absolute positions.

• - sich der erste Sensor 51.1 an der ersten Inkrementalspur 41.1 der Massverkörperung 40a des ersten Schienensegments 30a befindet, sodass der erste Sensor 51.1 geeignet positioniert ist, um mindestens eine Positionsmarkierung der ersten Inkrementalspur 41.1 der Massverkörperung 40a detektieren zu können;
• - sich der zweite Sensor 51.2 an der ersten Inkrementalspur 41.1 der Massverkörperung 40b des benachbarten zweiten Schienensegments 30b befindet, sodass der zweite Sensor 51.2 geeignet positioniert ist, um mindestens eine Positionsmarkierung der ersten Inkrementalspur 41.1 der Massverkörperung 40b des benachbarten zweiten Schienensegments 30b detektieren zu können;
• - sich der dritte Sensor 51.3 an der Absolutspur 45 des ersten Schienensegments 30a befindet, sodass der dritte Sensor 51.3 geeignet positioniert ist, um mindestens eine Positionsmarkierung der Absolutspur 45 detektieren zu können.

For a more detailed explanation of the above facts shows 3 the scanning 50 in two different positions, in which the scanning device 50 can be brought if they are - with regard to the rail 30 linearly guided - in the direction of the longitudinal axis 31 is moved. In 3 is for example the scanner 50 represented by a rectangle represented by a solid line - shown in the case where the scanning device 50 in one (in 3 marked by an arrow) position P1 was brought, so that the scanner 50 in an area of the linear rail 30 in which one end of the first rail segment 30a to one end of the adjacent second rail segment 30b borders. In this case, the sensors are 51.1 . 51.2 and 51.3 the sensor arrangement 51 in such a way with regard to the dimensional standard 40a of the first rail segment 30a and the dimensional standard 40b of the adjacent second rail segment 30b arranged that:

• - the first sensor 51.1 at the first incremental track 41.1 the dimensional embodiment 40a of the first rail segment 30a is located so that the first sensor 51.1 is suitably positioned to at least one position mark of the first incremental track 41.1 the dimensional embodiment 40a to be able to detect;
• - the second sensor 51.2 at the first incremental track 41.1 the dimensional embodiment 40b of the adjacent second rail segment 30b is located so that the second sensor 51.2 is suitably positioned to at least one position mark of the first incremental track 41.1 the dimensional embodiment 40b of the adjacent second rail segment 30b to be able to detect;
• - the third sensor 51.3 at the absolute track 45 of the first rail segment 30a located so that the third sensor 51.3 is suitably positioned to at least one position mark the absolute track 45 to be able to detect.

• - sich der erste Sensor 51.1 an der ersten Inkrementalspur 41.1 des einen zweiten Schienensegments 30b befindet, sodass der erste Sensor 51.1 geeignet positioniert ist, um mindestens eine Positionsmarkierung der ersten Inkrementalspur 41.1 des einen zweiten Schienensegments 30b detektieren zu können;
• - sich der zweite Sensor 51.2 an der ersten Inkrementalspur 41.1 des anderen (benachbarten) zweiten Schienensegments 30b befindet, sodass der zweite Sensor 51.2 geeignet positioniert ist, um mindestens eine Positionsmarkierung der ersten Inkrementalspur 41.1 des anderen zweiten Schienensegments 30b detektieren zu können;
• - sich der dritte Sensor 51.3 derart entfernt von der Absolutspur 45 des ersten Schienensegments 30a befindet, dass der dritte Sensor 51.3 nicht geeignet positioniert ist, um eine Positionsmarkierung der Absolutspur 45 detektieren zu können.

In 3 is also the scanner 50 represented by a rectangle represented by a dashed line - shown in the case where the scanning device 50 in one (in 3 marked by an arrow) position P2 was brought, so that the scanner 50 in an area of the linear rail 30 in which one end of a second rail segment 30b at one end of another (adjacent) second rail segment 30b borders. In this case, the sensors are 51.1 . 51.2 and 51.3 the sensor arrangement 51 in such a way with regard to the dimensional standard 40b of a second rail segment 30b and the dimensional standard 40b the other second rail segment 30b arranged that:

• - the first sensor 51.1 at the first incremental track 41.1 of a second rail segment 30b is located so that the first sensor 51.1 is suitably positioned to at least one position mark of the first incremental track 41.1 of a second rail segment 30b to be able to detect;
• - the second sensor 51.2 at the first incremental track 41.1 the other (adjacent) second rail segment 30b is located so that the second sensor 51.2 is suitably positioned to at least one position mark of the first incremental track 41.1 the other second rail segment 30b to be able to detect;
• - the third sensor 51.3 so removed from the absolute track 45 of the first rail segment 30a that is the third sensor 51.3 is not suitably positioned to a position marker of the absolute track 45 to be able to detect.

Notwithstanding the above items P1 and P2 can the scanning device 50 be brought to other positions at which both the first sensor 51.1 as well as the second sensor 51.2 each at the same first incremental track 41.1 the same scale 40a respectively. 40b one of the rail segments 40a or 40b is arranged so that the sensors 51.1 and 51.2 are suitably placed to exclusively position marks of the same first incremental track 41.1 to detect. Because the sensors 51.1 and 51.2 relative to each other by the distance D in the direction of the longitudinal axis 31 staggered, detect the sensors 51.1 and 51.2 in this case in each case different, arranged at different locations position markers, ie, as a rule, different position markers, which in the direction of the longitudinal axis 31 relative to each other have a distance which corresponds approximately to the distance D.

With regard to the generation of the above-mentioned signals S1 . S2 respectively. S3 In this context it is assumed that each of the sensors 51.1 . 51.2 and 51.3 for detecting position markings, at least one sensor element (or optionally several sensor elements), each sensor element being sensitive to a position mark to be detected (at least when the sensor element is placed in the vicinity of the position mark) and designed to generate a signal which is such depends on the arrangement of the sensor element relative to the position mark to be detected that a signal generated by the sensor element varies in dependence on a distance of the sensor element relative to the position mark to be detected. Will the scanner 50 in the direction of longitudinal axis 31 moves accordingly vary from those of the sensors 51.1 . 51.2 and 51.3 generated signals S1 . S2 and S3 depending on a location coordinate X, which the respective position of the scanning device 50 relative to the linear rail 30 in the direction of the longitudinal axis 31 features.

The ones from the sensors 51.1 respectively. 51.2 generated signals S1 and S2 usually show a periodic variation as a function of the spatial coordinate X of the scanner 50 , Especially the position markings of the first incremental track 41.1 periodic (equidistant) with respect to the longitudinal axis 31 are arranged. The signals S1 and S2 In this case, as a rule, essentially the same periodic signal course as a function of the spatial coordinate X of the scanning device is shown 50 (At least on condition that all position markings are identical and the sensors 51.1 and 51.2 have the same characteristics with respect to the detection of a position marker). Here are the signals S1 and S2 not necessarily identical with respect to a given time, especially as the sensors 51.1 and 51.2 relative to each other at a distance D with respect to the longitudinal axis 31 are arranged and consequently the signal waveform of the signal S1 as a function of the location coordinate X compared to the waveform of the signal S2 as a function of the location coordinate X must have a phase difference. The latter applies even if the sensors 51.1 and 51.2 both at the same first incremental track 41.1 the same scale 40a respectively. 40b are arranged. Here, the above-mentioned phase difference between the signals S1 and S2 the greater, the greater the distance D in relation to the period length d1 the first incremental track 41.1 is.

Furthermore, it should be noted that, although all the position markers, which at the same first incremental track 41.1 the same scale 40a respectively. 40b same rail segment 30a respectively. 30b belong, periodically with the period length d1 However, the periodicity of the arrangement of the position markings are arranged in a region of the rail 30 Be "disturbed" in which one of the rail segments 30a respectively. 30b to an adjacent rail segment 30a respectively. 30b borders.

Because of the linear rail 30 from several individual rail segments 30a respectively. 30b is composed and accordingly several dimensional embodiments 40a respectively. 40b each with a first incremental track 41.1 in the direction of the longitudinal axis 31 in fact, two adjacent first incremental tracks are usually arranged one behind the other 41.1 (ie, the first incremental track formed on one of the adjacent rail segments 41.1 and the first incremental track formed on the other of the adjacent rail segments 41.1 ) are arranged relative to each other such that an end of one of the two adjacent first incremental tracks 41.1 to one end of the other of the two adjacent first incremental tracks 41.1 borders. When mounting the individual rail segments is in terms of the respective positions to which the individual rail segments are attached, usually a certain amount of play (within certain tolerances). As a result, depending on the arrangement of two adjacent rail segments relative to one another, an end of one of two adjacent first incremental tracks 41.1 so to one end of the other of the two adjacent first incremental tracks 41.1 border that the position marker, which is the end of one of the two adjacent first incremental tracks 41.1 forms, relative to the position marker, which forms the end of the other of the two adjacent rail segments, in the direction of the longitudinal axis 31 has a distance which is more or less of the period length d1 the first incremental track 41.1 different.

If the sensor 51.1 under these circumstances in the longitudinal direction of the rail 30 from one of the two adjacent rail segments to the other of the two adjacent rail segments, the sensor generates 51.1 when scanning the respective first incremental track 41.1 a signal S1 , which as a function of the location coordinate X, a periodic variation (or a periodic waveform) with the period length d1 has, at least for the areas of the location coordinate X, which either an arrangement of the sensor 51.1 in the area of one of the two adjacent first incremental tracks 41.1 or an arrangement of the sensor 51.1 in the area of the other of the two adjacent first incremental tracks 41.1 correspond. At the transition from the one end of the first incremental track 41.1 one of the two adjacent rail segments to the one end of the first incremental track 41.1 however, the other of the two adjacent rail segments may be the signal S1 as a function of the location coordinate X have an abrupt signal change, which with a phase jump in the transition from a first incremental track 41.1 to the adjacent first incremental track 41.1 corresponds. This phase jump in the signal waveform S1 The larger the distance between the position mark, which is the end of one of the two adjacent first incremental tracks, the greater the distance between the position mark 41.1 and the position marker representing the end of the other of the two adjacent first incremental tracks 41.1 forms, in the direction of the longitudinal axis 31 from the period length d1 the first incremental track 41.1 different.

That of the second sensor 51.2 generated signal S2 shows a corresponding dependence on the location coordinate X analogous to the dependence of the signal S1 from the location coordinate X.

If the sensor 51.2 under these circumstances in the longitudinal direction of the rail 30 from one of the two adjacent rail segments to the other of the two adjacent rail segments, the sensor generates 51.2 when scanning the respective first incremental track 41.1 a signal S1 , which as a function of the location coordinate X, a periodic variation (or a periodic waveform) with the period length d1 has, at least for the areas of the location coordinate X, which either an arrangement of the sensor 51.2 in the area of one of the two adjacent first incremental tracks 41.1 or an arrangement of the sensor 51.2 in the area of the other of the two adjacent first incremental tracks 41.1 correspond. At the transition from the one end of the first incremental track 41.1 one of the two adjacent rail segments to the one end of the first incremental track 41.1 however, the other of the two adjacent rail segments may be the signal S2 as a function of the location coordinate X have an abrupt signal change, which with a phase jump in the course of the signal S2 as a function of the location coordinate X at the transition from the first incremental track 41.1 to the adjacent first incremental track 41.1 corresponds. This phase jump in the course of the signal S2 as a function of the location coordinate X, the greater the distance between the position marking, which is the end of the one of the two adjacent first incremental tracks 41.1 and the position marker representing the end of the other of the two adjacent first incremental tracks 41.1 forms, in the direction of the longitudinal axis 31 from the period length d1 the first incremental track 41.1 different.

As related to above 3 is explained, the sensors are 51.1 and 51.2 the sensor arrangement 51 the scanner 50 relative to the rail segments of the linear rail 30 each arranged such that - depending on the position of the scanning device 50 relative to the respective rail segments - either one of the sensors 51.1 or 51.2 or both sensors 51.1 and 51.2 is suitably placed, respectively, a position mark of a first incremental track 41.1 to detect at least one of the rail segments and accordingly the signal S1 and / or the signal S2 to create. Should the sensor 51.1 (or alternatively the sensor 51.2 ) at the transition from one end of the first incremental track 41.1 one of two adjacent rail segments to the one end of the first incremental track 41.1 of the other of the two adjacent rail segments may be temporarily positioned such that it does not have a position mark of one of the first incremental tracks 41.1 detect and accordingly no signal S1 (or alternatively no signal S2 ) is always guaranteed that the other sensor 51.2 (or alternatively the sensor 51.1 ) is just placed such that it has a position mark of one of the first incremental tracks 41.1 detect and accordingly a signal S2 (or alternatively a signal S1 ).

Furthermore, since both the signal S1 as well as the signal S2 as a function of the location coordinate X, at least for certain areas of the location coordinate X, in each case a periodic signal course with the period length d1 the first incremental track 41.1 show, allows a measurement of the two signals S1 and S2 during a movement in the direction of the longitudinal axis 31 , the respective changes of the measured signals S1 and S2 evaluate and from this a relative change in the position of the scanner 50 in the direction of the longitudinal axis 31 during the movement (according to the length of the scanner 50 traveled distance) or the position difference PD between the position of the scanner 50 at the beginning of the movement and the position of the scanner 50 at any later time after the beginning of the movement.

It should be noted that an evaluation of the signals S1 and S2 can be performed in a particularly simple manner when the Wegmessvorrichtung 10 is designed such that neither the course of the signal S1 nor the course of the signal S2 as a function of the location coordinate X of the scanner 50 at a transition of the sensor 51.1 or the sensor 51.2 from the one end of the first incremental track 41.1 one of two adjacent rail segments to the one end of the first incremental track 41.1 the other of the two adjacent rail segments does not have a phase jump which results in an abrupt change in the signal S1 or the signal would be connected. In order to avoid such a phase jump, it is possible, for example, during assembly of the individual rail segments to ensure that the distance between the position marking, which is the end of one of the two adjacent first incremental tracks 41.1 forms, and the position marking, which forms the end of the other of the two adjacent rail segments, in the direction of the longitudinal axis 31 either equal to the period length d1 the first incremental track 41.1 or equal to a multiple of the period length d1 is.

An evaluation of the signals S1 and S2 can be further simplified if the distance D of the sensors 51.1 and 51.2 in the direction of the longitudinal axis 31 is chosen such that the distance D equal to the period length d1 the first incremental track 41.1 or equal to a multiple of period length d1 is. In this case, the signals are pointing S1 and S2 as a function of the location coordinate X of the scanner 50 relative to each other on a phase difference, which is so large that the signals S1 and S2 the same course as a function of the spatial coordinate X of the scanner 50 exhibit. In this case, if both signals S1 and S2 available simultaneously, one of the two signals S1 respectively. S2 redundant.

As 3 Furthermore, the path measuring device comprises 10 for the evaluation of the sensors 51.1 . 51.2 and 51.3 can be generated signals a first evaluation 60 for one from the third sensor 51.3 Generable third signal S3 and a second evaluation device 65 for one from the first sensor 51.1 producible first signal S1 and one from the second sensor 51.2 producible second signal S2 , The first evaluation device 60 is accordingly with the third sensor 51.3 in one connection to one from the third sensor 51.3 generated signal S3 to be able to receive. Furthermore, the second evaluation device is available 65 with the first sensor 51.1 and the second sensor 51.2 in connection to one from the first sensor 51.1 generated signal S1 and one from the second sensor 51.2 generated signal S2 to be able to receive.

At a first commissioning of the distance measuring device 10 must be the scanner 50 first with respect to the first rail segment 30a be positioned or (optionally by means of a movement of the scanning device 50 in the direction of the longitudinal axis 31 ), that the third sensor 51.3 at least a section of the absolute track 45 the dimensional embodiment 40a of the first rail segment 30a which contains at least those position markers which are one of the predetermined absolute positions AP1 encoded until APn, so the third sensor 51.3 can detect those position markings which encodes the one of the predetermined absolute positions. For this purpose, the scanning device 50 for example along a section of the absolute track 45 in the direction of the longitudinal axis 31 be moved, wherein at the same time the first evaluation device 60 that from the third sensor 51.3 generated signal S3 evaluates and the second evaluation 65 that from the first sensor 51.1 generated signal S1 and the second sensor S2 generated signal S2 evaluates. The second evaluation device 65 is formed, the relative change of the spatial coordinate X of the scanning device 50 during the move to register while the first evaluation device 60 is formed, a change of the signal S3 during the relative change of the location coordinate X of the scanner 50 to register and evaluate. The change of the signal registered during the relative change of the location coordinate X in each case S3 is characteristic of the spatial arrangement of those position markings of the absolute track 45 , which from the third sensor 51.3 during the movement of the scanner 50 were detected. The registered change of the signal S3 therefore provides information about whether the detected position markings of the absolute track 45 one of the predetermined absolute positions coded or which of the predetermined absolute positions optionally by the third sensor 51.3 detected position markers are encoded.

Accordingly, the first evaluation device 60 designed, at a first commissioning of the distance measuring device 10 based on an evaluation of the third signal S3 to detect if the scanner 50 at one of the predetermined absolute positions AP1 to APn with respect to the first of the rail segments 30a located, and - if an evaluation of the third signal S3 shows that the scanner 50 at a first time t1 at one of the predetermined absolute positions with respect to the one of the rail segments 30a is - a first absolute value AW1 to determine which of these represents one of the predetermined absolute positions. The absolute value AW1 can, for example, a location coordinate of the scanner 50 correspond to the position of the scanner 50 at the first time t1 assigned.

Regarding the in 3 In the example shown below, it is assumed that the scanning device 50 at the first time t1 at the in 3 specified position P1 located and the position P1 one of the given absolute positions AP1 to AP n is, so that of the first evaluation device 60 determined first absolute value AW1 the position P1 according to 3 would be assigned. Following the date t1 can the scanning device 50 in any position in the linear rail area 30 be brought, which the scanning device during a movement in the direction of the longitudinal axis 41 can reach. In the example according to 3 For example, assume that the scanner 50 until one time t2 in the specified position P2 was moved.

The path measuring device 10 is designed such that the second evaluation device 65 after the first time t1 the first signal S1 and the second signal S2 during a first time interval between the first time t1 and the second time t2 evaluates and from the respective changes of the signals S1 and S2 during this first time interval, a position difference PD between the position P1 the scanner 50 at the beginning of the first time interval and the position P2 the scanner 50 at the second time t2 determined at the end of the first time interval. The position difference PD corresponds to the difference of the location coordinate of the scanner 50 which of the position P2 assigned, and the location coordinate of the scanner 50 which of the position P1 assigned.

As 3 Furthermore, the path measuring device comprises 10 an arithmetic unit 70 , This is formed from the first absolute value AW1 and that of the second evaluation device 65 determined position difference PD a second absolute value AW2 to calculate which is an absolute position of the scanner 50 at the second time t2 represented at the end of the first time interval. The second absolute value AW2 is the position P2 assigned and defined this clearly.

Will the scanner 50 after the time t2 to another, from P2 moved different position, then evaluates the second evaluation 65 the signals S1 and S2 or changes in the signals S1 and S2 continue off to the "current" position difference PD to determine which this other position from the position P1 at the time t1 different. Accordingly, the arithmetic unit 70 formed, a "current" second absolute value AW2 to calculate which uniquely identifies this other position. In this way it is ensured that the arithmetic unit 70 at any time after the time t1 a second absolute value AW2 which corresponds to the position at which the scanning device 50 is located at the respective time. At the time t1 is the second absolute value AW2 obviously identical to the first absolute value AW1 because at this time, the position difference PD is 0.

As 3 indicates, the arithmetic unit points 70 an output interface 71 on, over which the second absolute value AW2 can be output, for example, to a (not shown) display device for displaying the respective absolute position of the scanning device 50 and / or to a control device (not shown) for controlling a machine as a function of the respective absolute position of the scanning device 50 ,

As 1 and 3 indicate further, can (optional) the dimensional standard 40b a second rail segment 30b or multiple rail segments 30b or each of the rail segments 30b a second incremental track 41.2 which next to the first incremental track 41.1 the respective dimensional standard 40b in the direction of the longitudinal axis 31 extends and has a plurality of equidistantly arranged position markings. The position markings of the respective second incremental track 41.2 are in the direction of the longitudinal axis 31 arranged one behind the other in such a way that they extend in the direction of the longitudinal axis 31 extending periodic arrangement with a period length d2 (corresponding to the distance of two adjacent position markers of the incremental track 41.2 ) form. The respective second incremental track 41.2 is relative to the third sensor 51.3 the scanner 50 arranged such that they by means of the third sensor 51.3 is scannable and the position marks of the second incremental track 41.2 by means of the third sensor 51.3 are detectable (if the scanner 50 with respect to the respective second incremental track 41.2 is positioned accordingly).

The individual position markings of the second incremental track 41.2 can in the same way as the position markings of the first incremental track 41.1 be realized, whereby the period length d2 the second incremental track 41.2 from the period length d1 the first incremental track 41.1 can differentiate.

The third sensor 51.3 generates in the present example when scanning the respective second incremental track 41.2 a fourth signal S4 which is during a movement of the scanning device 50 in the direction of the longitudinal axis 31 along the respective second incremental track 41.2 as a function of the location coordinate X of the scanner 50 a periodic variation (or a periodic waveform) with the period length d2 having.

The first evaluation device 60 stands with the third sensor 51.3 in connection to a signal generated by the third sensor S4 receive and evaluate. The first evaluation device 60 In particular, it is designed to change the fourth signal S4 during a movement of the scanning device 50 in the direction of the longitudinal axis 13 to register and with a change in position of the scanner 50 to correlate. Furthermore, the arithmetic unit 70 is formed, the fourth signal S4 with the first signal S1 and / or the second signal S2 to compare. The arithmetic unit 70 is in particular designed, one at a change in position of the scanning device 50 generated change of the fourth signal S4 with corresponding changes of the first signal S1 and / or the second signal S2 to compare. Such a comparison of the signal S4 with the signal S1 and / or the signal S2 allows a check whether the changes of the signals S1 . S2 and S4 within predetermined tolerances with a certain change in position of the scanning device 50 correspond, and therefore provides an indication of whether the scanner 50 as expected works.

To the most accurate possible measurement of a change in position of the scanner 50 in the direction of the longitudinal axis 31 It is beneficial for the period length to allow d1 the first incremental 41.1 to give as small a value as possible. For the period length d2 that of the second incremental track 41.2 may suitably d2> d1 apply, especially in these circumstances, a control of the functionality of the scanner 50 is possible with sufficient accuracy.

The period length d2 the second incremental track 41.2 can therefore be independent of d1 be specified freely. To easily control the functionality of the scanner 50 to ensure d2 for example, a multiple of d1 be. For the in 1 and 3 illustrated second incremental track 41.2 For example, d2 = 2 x d1.

The period length d2 can for example be chosen so that d2 with one or more characteristic parameters of the path measuring device 10 is correlated, for example, with a "size" of the respective rail segment 30b (Characterized by the length, height and / or width of the rail segment 30b ) or an identification of a particular embodiment of the path measuring device 10 (provided the Wegmessvorrichtung 10 can be provided in various embodiments).

The absolute track 45 of the rail segment 30a comprises in the example according to 1 respectively. 3 a first coding 46 which information about the (or the) above-mentioned characteristic parameters of the Wegmessvorrichtung 10 contains. The first coding 46 is here as a certain (in the present example at one end of the absolute track 45 placed) arrangement of several position markers of the absolute track 45 realized and is accordingly by means of the third sensor 51.3 scannable and accordingly detectable and by means of the first evaluation 60 evaluable.

After a first scan of the first encoding 46 can therefore be the first evaluation 60 the respective characteristic parameters of the Wegmessvorrichtung 10 determine. Once the scanner 50 subsequently during a movement in the direction of the longitudinal axis 31 is enabled, the second incremental track 41.2 one of the second rail segments 30b can be sampled, the first evaluation 60 the fourth signal generated by the third sensor S4 evaluate and from a change of the signal as a function of the spatial coordinate X of the scanner 50 the period length d2 the second incremental track 41.2 determine. In this way, the first evaluation device 60 able to control whether the determined period length d2 the second incremental track 41.2 of the respective second rail segment 30b with the in the absolute track 45 contained first coding 46 is compatible or not.

Regarding 4 An embodiment of a linear guide for a movable body according to the invention is explained below. The 4 shows - in a schematic representation - a linear guide 1 which is a movable body 20 and a linear displacement measuring device 10 according to 3 includes. In 3 and 4 are denensprechend same or equivalent parts respectively designated by the same reference numerals. The linear guide 1 in particular has the same linear rail 30 on like the Wegmessvorrichtung 10 according to 3 ,

The movable body 20 the linear guide 1 is about (not shown) rolling elements on the linear rail 30 supported, so that the rolling elements a guided linear movement of the movable body 20 in the longitudinal direction of the linear rail 30 (ie towards the in 1 illustrated longitudinal axis 31 ) enable. A scanner 50 the linear position measuring device 10 according to 3 is on the movable body 20 arranged so that the scanning device 50 during a movement of the movable body 20 in the direction of the longitudinal axis 31 the linear rail 30 is moved and the position markings of the individual scale embodiments 40a and 40b can scan. The linear guide 1 is in terms of the design and function of the scanner 50 , the first evaluation device 60 , the second evaluation device 65 and the arithmetic unit 70 each identical to the Wegmessvorrichtung 10 according to 3 , Accordingly, the movable body needs 20 at a first start-up of the linear guide 1 first with respect to the first rail segment 30a be positioned such that the third sensor 51.3 at least position markings of the absolute track 45 can detect which one of the predetermined absolute positions AP1 until APn code, and the evaluation the first absolute value AW1 can determine which of the predetermined absolute position corresponds, which is encoded by means of the detected position markers. Any change in position of the movable body 20 in the direction of the longitudinal axis 31 is from the second evaluation device 65 by means of an evaluation of the from the sensors 51.1 and 51.2 generated signals S1 and S2 determined. Accordingly, the arithmetic unit 70 a second absolute value AW2 ready, which corresponds to the position at which the scanning device 50 or the movable body 20 is located respectively. In 4 are the movable body 20 and the scanner 50 each shown in two different positions: in the event that the scanning device 50 at the position P1 located, and in the event that the scanning device 50 at the position P2 located (analogous to 3 ).

The linear guide 1 according to 4 As a whole, it can be part of a machine which, for example, has a (in 3 not shown) electric drive motor for moving the movable body 20 , a (in 3 not shown) machine control for driving the electric drive motor and optionally other controllable components of the machine and a power supply means for supplying the electric drive motor, the other controllable components of the machine and / or the machine control with energy, wherein the machine control is formed, during operation of the machine that of the arithmetic unit 70 provided second absolute value AW2 to receive and the machine in response to the second absolute value AW2 to control.

The scanning device 50 , the first evaluation device 60 , the second evaluation device 65 and / or the arithmetic unit 70 include electronic components and require a supply of electrical energy for their operation. As 4 indicates, may be a separate electrical power supply 80 be provided, which is formed, after a first startup of the linear displacement measuring device 10 or the linear guide 1 an uninterrupted supply of electrical energy to the scanner 50 , the first evaluation device 60 , the second evaluation device 65 and / or the arithmetic unit 10 to allow, regardless of a supply of the electric drive motor, the other controllable components of the machine and / or the machine control with energy.

The separate electrical power supply device 80 ensures that the scanning device 50 , the first evaluation device 60 , the second evaluation device 65 and / or the arithmetic unit 10 even then are functional and, accordingly, one of the absolute position of the scanner 50 corresponding second absolute value AW2 provide, if the operation of the machine itself is interrupted, for example by interrupting the supply of the electric drive motor, the other controllable components of the machine and / or the machine control with energy. If the operation of the machine is continued after a restoration of the supply of the electric drive motor, the other controllable components of the machine and / or the machine control with energy, the arithmetic unit is 70 capable of giving the machine control a second absolute value AW2 which is the instantaneous absolute position of the scanner 50 at the time of continued operation of the machine. The latter is also true in the event that the scanning device 50 during the interruption of the supply of the electric drive motor, the other controllable components of the machine and / or the machine control with energy in the direction of the longitudinal axis 31 was moved.

All second rail segments 30b (including at the respective second rail segment 30b existing dimensional standard 40b) the rail 30 the Wegmessvorrichtung 10 or the linear guide 1 can be identically constructed to allow several to build the rail 30 required rail segments 30b interchangeable and / or interchangeable.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 7432497 B2 [0011]
• EP 2533018 A1 [0015]

Claims (11)

A linear path measuring device (10) for determining an absolute position, comprising: a) a linear rail (30) which has a longitudinal axis (31) and is composed of a plurality of individual rail segments (30a, 30b), which rail segments are arranged one behind the other in the direction of the longitudinal axis (31), wherein each of the rail segments (30a, 30b) has a dimensional representation (40a, 40b) which comprises at least one first incremental track (41.1) extending in the direction of the longitudinal axis (31) with a plurality of equidistantly arranged position markings, and wherein the dimensional standard (40a ) of one of the rail segments (30a) next to the first incremental track (41.1) of this scale (40a) an absolute track (45) with a plurality of position markings for encoding a plurality of predetermined absolute positions, which lie in the direction of the longitudinal axis (31) one behind the other; b) a scanning device (50) having a sensor arrangement (51) for scanning the dimensional standards (40a, 40b), which sensor arrangement comprises at least one first sensor (51.1), a second sensor (51.2) and a third sensor (51.3), wherein the scanning device (50) is guided with respect to the rail (30) such that it is movable in the direction of the longitudinal axis (31) along a plurality of the rail segments (30a, 30b), and wherein the first sensor (51.1) is designed to detect at least one position marking of the first incremental track (41.1) of one of the rail segments (30a, 30b) and to generate a first signal (S1) which contains information about a position of the scanning device (50). relative to the at least one position marker detected by the first sensor (51.1), wherein the second sensor (51.2) is designed to detect at least one position marking of the first incremental track (41.1) of one of the rail segments (30a, 30b) and to generate a second signal (S2) which contains information about a position of the scanning device (50). relative to the at least one position marker detected by the second sensor (51.2), wherein the first sensor (51.1) and the second sensor (51.2) are offset in the direction of the longitudinal axis (31) relative to one another by a predetermined distance (D), so that the scanning device (50) with respect to each two adjacent rail segments (30a, 30b) in a position (P1) can be brought, in which the first sensor (51.1) detects at least one of the position markings of the first incremental track (41.1) of the dimensional scale (40a) of the one of the two adjacent rail segments (30a) and the second sensor (51.2) at least detects one of the position markings of the first incremental track (41.1) of the scale (40b) of the other of the two adjacent rail segments (30b), wherein the third sensor (51.3) is adapted to scan the absolute track (45) of the scale (40a) of the one of the rail segments (30a) and to generate a third signal (S3) containing information about a position of the scanner (50) relative to to the given absolute positions; c) a first evaluation device (60) for the third signal (S3), which is designed to detect whether the scanning device (50) is located at one of the predetermined absolute positions with respect to the one of the rail segments (30a), and - if an evaluation of the third signal (S3) shows that the scanning device (50) at a first time at one of the predetermined absolute positions (P1) with respect to the one of the rail segments (30a) - to determine a first absolute value (AW1), which one the predetermined absolute positions (P1) represents; d) a second evaluation device (65) for the first signal (S1) and the second signal (S2), which is formed after the first time the first signal and the second signal during a first time interval between the first time and a second time and to determine a position difference (PD) between the position (P1) of the scanner (50) at the beginning of the first time interval and a position (P2) of the scanner (50) at the second time at the end of the first time interval; e) a computing unit (70), which is designed to calculate from the first absolute value (AW1) and the position difference (PD) determined by the second evaluation device (65) a second absolute value (AW2), which determines an absolute position of the scanning device (50 ) at the second time at the end of the first time interval. Linear displacement measuring device (20) according to Claim 1 wherein the scanning device (50), the first evaluation device (60), the second evaluation device (65) and / or the computing unit (70) are operable by means of a supply of electrical energy and an electrical power supply device (80) is provided, which is formed to allow after the first time an uninterruptible supply of electrical energy to the scanning device, the first evaluation device, the second evaluation device and / or the computing unit. Linear displacement measuring device (20) according to one of Claims 1 - 2 wherein the dimensional scale (40b) of at least one of the rail segments (30b) - with the exception of one of the rail segments (30a) having the absolute track (45) - comprises a second incremental track (41.2) adjacent to the first incremental track (41.1) this at least one of the rail segments (30b) extends in the direction of the longitudinal axis (31) and has a plurality of equidistantly arranged position markings, and the second incremental track (41.2) relative to the third sensor (51.3) of the scanning device (50) is arranged such that the second incremental track (41.2) by means of the third Sensor (51.3) is scanned and the position markings of the second incremental track (41.2) by means of the third sensor (51.3) are detectable. Linear displacement measuring device (20) according to Claim 3 wherein two adjacent position markings of the second incremental track (41.2) are arranged at a distance (d2) from one another which is greater than the distance (d1) between two adjacent position markings of the first incremental track (41.1). Linear displacement measuring device (20) according to Claim 3 or 4 wherein the third sensor (51.3) is designed to generate a fourth signal (S4) when scanning the second incremental track (41.2), and the arithmetic unit (70) is configured to generate the fourth signal (S4) with the first signal (S1) and / or the second signal (S2). Linear displacement measuring device (20) according to one of Claims 3 - 5 wherein the absolute track (45) of one of the rail segments (30a) comprises a first coding (46) containing information about at least one characteristic parameter of at least one of the other of the rail segments (30b) of the linear rail (30) and the first one Coding (46) by means of the third sensor (51.3) is detectable. Linear displacement measuring device (20) according to Claim 6 , wherein the at least one characteristic parameter is: a size of at least one of the other of the rail segments (30b) or a distance (d2) between two adjacent position marks of the second incremental track (41.2). Linear displacement measuring device (20) according to one of Claims 1 - 7 wherein the linear rail (30) is composed of more than two of the rail segments (30a, 30b) and all the rail segments (30b) are identical, except for the one of the rail segments (30a) having the absolute track (45). Linear displacement measuring device (20) according to Claim 8 wherein the rail segments (30a, 30b) are mountable in any order one behind the other to form the linear rail (30). Linear displacement measuring device (20) according to Claim 8 or 9 wherein each of the rail segments (30b) is interchangeable with an identical rail segment except for the one of the rail segments (30a) having the absolute track (45). Linear guide (1) comprising a movable body (20) and a linear displacement measuring device (10) according to one of Claims 1 - 10 wherein the movable body (20) is supported by rolling elements on the linear rail (30) of the linear displacement measuring device (10) so that the rolling elements allow guided linear movement of the movable body (20) in the longitudinal direction of the linear rail (30), and the scanning device (50) of the linear displacement measuring device (10) is arranged on the movable body (20).

Images