Encoder system and method for determining readhead position in an encoder system - Patents.com

Abstract

An encoder system, comprising: a read head (10) having at least one first position sensor (1, 1.1, 1.2) and at least one second position sensor (2, 2.1, 2.2), said position sensors (1, 1.1, 1.2, 2, 2.1, 2.2) arranged at a fixed distance (a, a1, a2, a3, a4, a6, a6) from one another in a reading direction (12); a real measure (30) having a longitudinal direction (l) and a transverse direction (q), the real measure (30) having in the longitudinal direction (l) a first code section (32) comprising a first absolute encoded code track (34); An encoder system, in which the read head (10) and the real scale (30) are arranged relative to one another such that a reading direction (12) corresponds to a longitudinal direction (l) and such that the read head (10) and the real scale (30) are movable relative to the reading direction (12) and such that a first sensor position (p1, p1.1, p1.2) respectively on the real scale (30) can be detected by at least one first position sensor (1, 1.1, 1.2) and simultaneously a second sensor position (p2, p2.1, p2.2) respectively on the real scale (30) can be detected by at least one second position sensor (2, 2.1, 2.2), as well as a method for determining a read head position (p) in an encoder system (20).

Description

[Technical Field]

[0001] The present invention relates to an encoder system and a method for determining readhead position in an encoder system. [Background technology]

[0002] Absolute position or rotation angle measurement systems, also known as encoder systems, have been essential components in automation for decades. They typically include a readhead with a position sensor and a material scale. The position sensor and material scale are attached to relatively movable mechanical elements so that the position sensor can scan the material scale and determine the sensor position. The sensor position thus determined typically corresponds to the readhead position. Compared to so-called incremental measurement systems, which require the readhead to first move toward a unique reference mark after the supply voltage is switched on in order to determine the position, absolute systems have the advantage that, after switching on, each position on the material scale to be scanned can be determined as a unique absolute position.

[0003] In practice, cases often arise where the detected sensor position is incorrect due to contamination of the position sensor or the mass scale, or the influence of external disturbances such as magnetic fields, etc. The resulting position change makes it possible to recognize an incorrect initial position, since the monotonicity underlying each absolute measurement system is disturbed (a detected sensor position n is not followed by n+1 or n-1).

[0004] Another problem is presented by the fact that, especially when glass scales are used in optical systems, the assembly and handling of particularly long scales is very difficult: for example, a 5-meter long, one-piece glass scale requires a great deal of effort to transport and assemble.

[0005] To make the determination of the read head position more reliable after switching on the supply voltage, it is known to use two position sensors that scan the same spot on the scale and to compare the sensor positions of these sensors. If there is a disturbance at the corresponding position, for example due to contamination of the scale, both position sensors will detect an incorrect position. Therefore, a reliable determination of the read head position is not currently possible.

[0006] The principle of arranging a material scale in the form of short, easy-to-handle segments is shown in Patent Document 1. This improves assembly and handling. However, this principle entails a loss of measurement accuracy, particularly due to misalignment of the segments when they are assembled. For example, gaps between the segments can result in the overall length of the material scale being longer than that of a comparable one-piece material scale.

[0007] Furthermore, the measurement accuracy of the encoder system is usually affected by changes in the length of the material measure, especially as a result of temperature dependence. The above scenario will result in the detected readhead position deviating from the actual readhead position. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] European Patent No. 2288876 Summary of the Invention [Problem to be solved by the invention]

[0009] It is therefore an object of the present invention to provide an encoder system that allows for a simple, reliable and accurate determination of the read head position regardless of the influence of external disturbances, and that is simple and inexpensive to manufacture.It is another object of the present invention to provide a method that allows for an unambiguous, reliable and accurate determination of the read head position of an encoder system despite the influence of external disturbances. [Means for solving the problem]

[0010] The above problem is solved according to the invention by an encoder system having the features of claim 1 and by a method for determining the readhead position in an encoder system having the features of claim 15.

[0011] Advantageous embodiments and developments of the invention are set forth in the dependent claims. The encoder system according to the present invention has the following characteristics: a read head having at least one first position sensor and at least one second position sensor, the position sensors being arranged at a fixed distance from each other in a reading direction; and a real measure having a longitudinal direction and a transverse direction, the real measure having a first code section in the longitudinal direction which includes a first absolutely encoded code track, the read head and the real measure being arranged relative to each other such that the reading direction corresponds to the longitudinal direction and such that the read head and the real measure are movable relative to the reading direction and such that the at least one first position sensor can detect the respective first sensor position on the real measure and simultaneously the at least one second position sensor can detect the respective second sensor position on the real measure.

[0012] The reading direction is particularly defined by the direction in which the reading head is moved relative to the real scale when used as specified in the encoder system. The position sensor is suitable for scanning the absolute coding code track and is therefore particularly configured to be able to detect position information arranged on the absolute coding code track. A reading head having a plurality of first position sensors and / or a plurality of second position sensors is particularly configured in such a way that all position sensors are arranged spaced apart from one another in the reading direction.

[0013] The position sensors are preferably aligned perpendicular to the reading direction. The spaced apart arrangement of the at least one first position sensor and the at least one second position sensor allows the read head to detect, in particular, at least two different sensor positions. The read head position can be determined from the detected sensor positions. The position sensors can be configured to detect each sensor position in the form of a digital value. The resolution of a specific read head position can increase with the number of position sensors.

[0014] By positioning the position sensors at fixed distances from each other, if one of the position sensors detects an invalid or implausible sensor position, the correct sensor position of one of the position sensors and the read head position can be inferred from the sensor position detected by at least one other position sensor, which may be due to, for example, dirt, etc.

[0015] A detected sensor position is considered plausible, especially if it actually appears in the corresponding code track. A sensor position detected by a particular position sensor is considered plausible, especially if it can be assumed that the sensor position detected by one position sensor matches its actual sensor position at least to a sufficiently accurate approximation, especially based on the known fixed distances of the position sensors and the sensor positions detected by the remaining position sensors.

[0016] The weight scale is preferably configured as a glass scale, and the at least one first sensor position and the at least one second sensor position on the weight scale can be detected simultaneously, so that the corresponding read head position can be determined from at least two different sensor positions.

[0017] It is particularly preferred that the encoder system have two first position sensors and two second position sensors. This allows the readhead to have a total of four position sensors. This allows for a particularly reliable indication of the readhead position, especially compared to a readhead embodiment with two position sensors. In an embodiment using two position sensors, if both position sensors detect a plausible sensor position, the detected sensor position may deviate excessively from the fixed distance of the position sensors, making it impossible to determine which of the two detected positions is plausible. Therefore, a reliable readhead position cannot be determined in such a situation. Increasing the number of position sensors typically increases redundancy and therefore increases the reliability of determining the readhead position. In an embodiment using two first position sensors and two second position sensors, if one of the sensors detects an incorrect but plausible sensor position, it is easy to determine which of the detected sensor positions is plausible based on the sensor positions detected by the remaining three position sensors. By arranging four position sensors on the readhead, an erroneously detected sensor position can be detected even if another position sensor detects an implausible sensor position.

[0018] In particular, the two first position sensors and the two second position sensors are arranged alternately on the read head, so that in the reading direction, the first first position sensor is followed by the first second position sensor, the second first position sensor, and the second second position sensor in this order.

[0019] In a preferred embodiment of the invention, the position sensor is configured as an optical position sensor. With the optical position sensor, the sensor position can be determined very accurately and with high resolution. It is particularly preferred that the position sensor is configured as an optical reflective position sensor. The position sensor may also be configured as an inductive, magnetic, or capacitive position sensor.

[0020] In particular, each of the position sensors is suitable for simultaneously scanning the absolute coding code track and the incremental coding code track. Thus, each of the position sensors is particularly configured to detect position information arranged on the incremental coding code track in addition to position information arranged on the absolute coding code track. By being able to simultaneously scan the absolute coding code track and the incremental coding code track, the position of each sensor can be detected with higher accuracy.

[0021] The position sensors can be arranged on an integrated sensor support with a thermal expansion coefficient of 2 ppm / K or less. This allows for negligible influence of temperature changes on the fixed distance between the position sensors. In particular, if temperature changes simultaneously cause non-negligible length changes in the scanned mass, the thermal expansion of the mass can be determined and possibly compensated for from the sensor position simultaneously detected by the position sensor. It is particularly preferred that the sensor support be made of quartz glass with a thermal expansion coefficient of 1 ppm / K.

[0022] In a preferred embodiment of the present invention, the first code section has an incrementally encoded first code track. Therefore, the first code section can have a first absolute-encoded code track and a first incremental-encoded code track. In particular, the first incremental-encoded code track is arranged horizontally next to the first absolute-encoded code track and vertically parallel to the first absolute-encoded code track. The first absolute-encoded code track and the first incremental-encoded code track can be arranged side by side such that a position sensor suitable for simultaneously scanning the absolute-encoded code track and the incremental-encoded code track can simultaneously scan the first absolute-encoded code track and the first incremental-encoded code track.

[0023] The first incremental coding code track is particularly configured to have a periodic repeating incremental code whose period can be assigned absolutely via the absolute coding code track. In particular, the incremental coding code track has finer divisions than the absolute coding code track, and therefore has a higher resolution than the absolute coding code track. Therefore, by simultaneously scanning the absolute coding code track and the incremental coding code track, a highly resolved absolute sensor position can be detected.

[0024] The material scale can have a second code section, and the read head and material scale are arranged relative to each other such that at least one first position sensor can detect the respective first sensor position in the first code section, and at the same time at least one second position sensor can detect the respective second sensor position in the second code section, thereby achieving higher redundancy and therefore higher reliability of the encoder system.

[0025] The second code section can have a second absolute-encoded code track. Furthermore, the second code section can have a second incremental-encoded code track. In this case, the first code section and the second code section can be arranged such that the first incremental-encoded code track and the second incremental-encoded code track face each other. In one embodiment of the present invention, the second incremental-encoded code track can be formed by the first incremental-encoded code track, thereby providing a real measure with two absolute-encoded code tracks and one incremental-encoded code track.

[0026] In particular, the first and second code sections are arranged in opposite directions. Thus, in the vertical direction, the first code section can have an ascending counting direction and the second code section a descending counting direction, or vice versa. Starting from the at least one first detection sensor position and the at least one second detection sensor position, the readhead position can be determined according to different calculation rules. This allows for additional reliability when determining the readhead position.

[0027] In one embodiment of the present invention, the weight scale has at least one weight scale segment including a first segment end and a second segment end. This allows the weight scale to be easily assembled, and handling during assembly and transportation may be simplified. During assembly, in particular, multiple weight scale segments are arranged one behind the other to appropriately size the overall length of the weight scale. When assembling the weight scale, an offset in the form of a gap may be provided between two consecutive segment ends. This simplifies assembly.

[0028] The mass scale can be formed in a linear and / or arc-shaped and / or circular shape. In particular, the mass scale can be formed flexibly. If the mass scale is formed in a circular shape, it can be arranged so that the horizontal and vertical directions of the mass scale are perpendicular to the radius of the circle on which it is formed. Therefore, the readhead position sensor is particularly aligned at least approximately toward the center of the circle. In this way, the position of the readhead on the circumference can be determined. The corresponding rotation angle can then be determined from the readhead position. Therefore, the encoder system can be used to determine the rotation angle, especially in applications where large-diameter shafts are present and high positional accuracy is required, such as in astronomical observatories.

[0029] In particular, the encoder system has an evaluation unit for evaluating the sensor positions, which is configured to determine the readhead position from the simultaneously detected sensor positions. The readhead position can be determined, in particular, by averaging the detected sensor positions. In this case, the readhead position can be defined arbitrarily in relation to the positions of the position sensors on the readhead. For example, the readhead position can be centered between at least one first position sensor and at least one second position sensor. Thus, by averaging the sensor positions detected by multiple, spaced-apart position sensors, the resolution of the readhead position determined therefrom can be increased.

[0030] The evaluation unit can be configured to check the validity and / or plausibility of the sensor positions and to prevent invalid and / or inconclusive sensor positions from being used to determine the readhead position, so that the readhead position can be determined even if one or some of the detected sensor positions cannot be used, i.e. are invalid or inconclusive.

[0031] The evaluation unit preferably has a storage means for storing the sensor positions and / or the readhead positions. This allows, in particular, specific sensor positions and / or readhead positions to be stored and used at a later time. In particular, in the case of a real scale having a gap between two consecutive segment ends, the gap can be detected and stored during the learning operation. If one of the position sensors detects a gap during later operation, the sensor position detected by that sensor can be classified, for example, as plausible but not convincing.

[0032] In particular, an encoder system having a first code section and a second code section can have multiple material scales, and the first code section and the second code section can be arranged differently in each material scale. In particular, the material scales are arranged one behind the other in the longitudinal direction. This allows the length of the measuring section, from which the readhead position can be determined, to be equal to the number of material scales arranged one behind the other. Due to the different arrangements of the first code section and the second code section, the difference between the sensor positions simultaneously detected by the first position sensor and the second position sensor, respectively, varies between the individual material scales. This allows, in particular, absolute and unambiguous determination of each position that the readhead can take in the measuring section. For example, in each material scale, the first code section can be shifted relative to the second code section by an absolute value compared to the previous material scale. The maximum length of the material scale is determined, in particular, only by the number of possible combinations of the first code section and the second code section.

[0033] A method for determining a readhead position in an encoder system according to one of the above-described embodiments comprises: simultaneously detecting a first sensor position of each of the at least one first position sensor and a second sensor position of each of the at least one second position sensor; - checking the validity and / or plausibility of each sensor position by comparison with each other sensor position detected at the same time; determining the readhead position based on the plausible and / or plausible sensor positions.

[0034] An embodiment of the present invention will be described with reference to the following drawings. [Brief explanation of the drawings]

[0035] [Figure 1] FIG. 1 is a schematic side view of a first embodiment of an encoder system. [Figure 2]FIG. 10 is a schematic top view of a second embodiment of an encoder system. [Figure 3] FIG. 10 is a schematic top view of a third embodiment of an encoder system. [Figure 4] FIG. 10 is a schematic top view of a fourth embodiment of an encoder system. [Figure 5] FIG. 10 is a schematic side view of a fifth embodiment of an encoder system. [Figure 6] FIG. 6 is a detailed schematic diagram of an embodiment of the encoder system shown in FIG. 5. [Figure 7] FIG. 10 is a detailed schematic diagram of a sixth embodiment of an encoder system. [Figure 8] FIG. 10 is a detailed schematic diagram of a seventh embodiment of an encoder system. [Figure 9] FIG. 1 is a schematic diagram of a first embodiment of a substance scale. [Figure 10] FIG. 10 is a schematic diagram of a second embodiment of the substance scale. [Figure 11] FIG. 10 is a schematic diagram of a third embodiment of a substance scale. DETAILED DESCRIPTION OF THE INVENTION

[0036] 1-11 show various views of various embodiments. For clarity, not all reference symbols are used in all views. The same reference symbols are used for the same and functionally identical parts.

[0037] FIG. 1 shows a schematic side view of a first embodiment of an encoder system 20 with a read head 10 and a material scale 30. The read head 10 has a first position sensor 1 and a second position sensor 2. The position sensors 1, 2 are suitable for scanning an absolute encoded code track 34 and are arranged at a fixed distance a from each other in a reading direction 12. The position sensors 1, 2 can be arranged on an integrated sensor support 14. The sensor support 14 preferably has a thermal expansion coefficient of less than or equal to 2 ppm / K. It is particularly preferred that the sensor support 14 is made of quartz glass, which has a thermal expansion coefficient of approximately 1 ppm / K. The read head 10 can have a read head housing 16 in which the position sensors 1, 2 are arranged. The position sensors 1, 2 can be formed as optical position sensors.

[0038] As shown in FIG. 2 , the real measure 30 has a longitudinal direction l and a transverse direction q. In the longitudinal direction l, the real measure 30 has a first code section 32 having a first absolute-encoded code track 34. Furthermore, the first code section 32 can have a first incremental-encoded code track 36. The read head 10 and the real mass 30 are arranged relative to each other such that the reading direction 12 corresponds to the longitudinal direction l and such that the read head 10 and the real mass 30 can move relative to each other in the reading direction l. Furthermore, the read head 10 and the real mass 30 are arranged relative to each other such that a first sensor position p1 on the real mass 30 can be detected by the first position sensor 1, and simultaneously a second sensor position p2 on the real mass 30 can be detected by the second position sensor. The position sensors 1, 2 are particularly suitable for simultaneously scanning the first absolute-encoded code track 34 and the first incremental code track 36.

[0039] The first incremental encoding code track 36 is arranged, in particular in the longitudinal direction l, parallel to the first absolute encoding code track 34 and next to it in the transverse direction q. Furthermore, the first incremental encoding code track 34 is particularly configured so that it has a periodically repeating incremental code, the period of which can be assigned absolutely via the absolute encoding code track 34. In particular, the incremental encoding code track 36 has finer divisions than the absolute encoding code track 34 and therefore a higher resolution. Therefore, by simultaneously scanning the absolute encoding code track 34 and the incremental encoding code track 36, highly resolved sensor positions p1, p2 can be detected.

[0040] The material measure 30 shown in Figures 2 and 3 each has a first material measure segment 38 and a second material measure segment 40. Each material measure segment 38, 40 has a first segment end 42 and a second segment end 44. An offset in the form of a gap 46 may be provided between consecutive segment ends 44, 42. In Figures 2 and 3, the material measure segments 38, 40 are shown with a diagonal interruption to enable recognition that the material measure segments 38, 40 may extend over a greater length.

[0041] 3 shows, the read head 10 can have a first first position sensor 1.1 and a second first position sensor 1.2 as well as a first second position sensor 2.1 and a second second position sensor 2.2. In particular, the two first position sensors 1.1, 1.2 and the two second position sensors 2.1, 2.2 are arranged alternately on the read head, so that in the reading direction 12 the first first position sensor 1.1 is followed in this order by the first second position sensor 2.1, the second first position sensor 1.2 and the second second position sensor 2.2.

[0042] As shown in FIG. 2, the sensor position p1 can be detected by the first position sensor 1, and the sensor position p2 can be detected by the second position sensor. Accordingly, the first first position sensor 1.1 can detect the first first sensor position p1.1, the second first position sensor 1.2 can detect the second first sensor position p1.2, the first second position sensor 2.1 can detect the first second sensor position p2.1, and the second position sensor 2.2 can detect the second second sensor position p2.2 (and FIG. 3). In particular, the readhead position p is determined from the sensor positions p1, p2 or p1.1, p1.2, p2.1, and p2.1. The readhead position p can be determined, for example, by averaging the sensor positions p1, p2 or p1.1, p1.2, p2.1, and p2.2. The detection of the sensor positions p1 and p2 or p1.1, p1.2, p2.1, p2.2 is preferably carried out simultaneously.

[0043] To evaluate the sensor positions p1, p2 or p1.1, p1.2, p2.1, p2.2, the encoder system 20 can have an evaluation unit (not shown) configured to determine the readhead position p from the simultaneously detected sensor positions p1, p2 or p1.1, p1.2, p2.1, p2.2, respectively. The readhead position p can be defined arbitrarily in relation to the detected sensor positions p1, p2 or p1.1, p1.2, p2.1, p2.2. In particular, the readhead position p is defined midway between the detected sensor positions p1, p2 or p1.1, p1.2, p2.1, p2.2.

[0044] 2 and 3, by virtue of the position sensors 1, 2 or 1.1, 1.2, 2.1, 2.2 being arranged at a fixed distance from one another in the reading direction, it is also possible to determine if the read head p overlaps the gap 46. In particular, before the start of operation, a learning operation is carried out in which the gap 46 is detected and stored. For this purpose in particular, the evaluation unit can have storage means for storing the sensor positions p1, p2 or p1.1, p1.2, p2.1, p2.2 and / or the read head position p.

[0045] 4 may have, in addition to the first code section 32 including the first absolute encoding code track 34 and the first incremental encoding code track 36, a second code section 48 including a second absolute encoding code track 50 and a second incremental encoding code track 52. In particular, the first code section 32 and the second code section 48 are arranged in opposite directions. Particularly preferably, the first code section 32 may have a first count direction 54 formed to ascend in the vertical direction 1, and the second code section 48 may have a second count direction 56 formed to descend in the vertical direction 1.

[0046] In the embodiment shown in Fig. 4, the position sensors 1.1, 1.2, 2.1, 2.2 can be arranged at fixed distances a1 to a6 from one another in the reading direction 12. In particular, the first position sensors 1.1, 1.2 are arranged to detect a first code section, and the second position sensors 2.1, 2.2 are arranged to detect a second code section 48.

[0047] When determining the readhead position p, particularly implausible and / or unconvincing sensor positions p1, p2 or p1.1, p1.2, p2.1, p2.2 are not used. How the plausibility check can be carried out is explained below on the basis of the example shown in Figure 4. In this case, it should be noted in particular that, in comparison with the example shown in Figures 2 and 3, the first code section 32 and the second code section 48 are arranged in opposite directions to each other.

[0048] In particular, the validity of all simultaneously detected sensor positions p1.1, p1.2, p2.1, p2.2 exists if all of the following conditions are met: p1.1+p2.1=a4, p1.2+p2.2=a6, p1.2-p1.1=a3, p2.1-p2.2=a2, p1.1+p2.2=a1, p2.1+p1.2=a5.

[0049] Such an evaluation of simultaneously detected sensor positions p1.1, p1.2, p2.1, p2.2 may also confirm that a single detected sensor position p1.1, p1.2, p2.1, p2.2 is invalid.

[0050] Furthermore, by comparing the simultaneously detected sensor positions p1.1, p1.2, p2.1, p2.2 with the fixed distances a1 to a6, systematic changes, such as changes in the length of the material scale as a result of temperature changes, can be recognized and compensated for. In particular, for this purpose, the position sensors 1.1, 1.2, 2.1, 2.2 can be arranged on a one-piece sensor support 14 made of quartz glass. This also applies to the embodiment shown in Figures 2 and 3.

[0051] 5 and 6 show another embodiment of the encoder system 20. In this case, the mass measure 30 can be circular. In particular, the mass measure 30 is arranged on a shaft 58 having a shaft radius 60. The mass measure 30 can then be formed by a first mass measure segment 38 having a first segment end 42 and a second segment end 44. In particular, a gap 46 is provided between the first segment end 42 and the second segment end 44. This significantly simplifies the assembly of the mass measure 30 onto the shaft 58. Following the explanation for this embodiment shown in FIGS. 2 and 3, the readhead position p can be reliably and unambiguously detected even when the readhead 10 is arranged on the gap 46.

[0052] The material scale 30 is arranged in particular such that the transverse direction q and the longitudinal direction l are arranged perpendicular to the shaft radius 60. The position sensors 1.1, 1.2, 2.1, 2.2 of the read head 10 are in particular aligned at least approximately towards the shaft centre point and thus towards the centre point of the circle of the circularly shaped material scale 30.

[0053] In that case, the mass scale 30 is arranged in particular on the outer radius of the shaft 58. Alternatively, the mass scale 30 can be arranged on the inner radius of the shaft 58, as shown in Figure 7, in particular if the shaft 58 is configured as a hollow shaft. In contrast to the embodiment shown in Figures 5 and 6, the read head 10 can be arranged inside the shaft 58.

[0054] 8 shows another embodiment in which the mass scale 30 can be circular. In this case, the mass scale 30 is arranged in particular so that the transverse direction q is aligned with the shaft radius 60 and the longitudinal direction 1 is aligned perpendicular to the shaft radius 60. The position sensors 1.1, 1.2, 2.1, 2.2 of the read head 10 are in particular at least approximately aligned with the longitudinal axis of the shaft (not shown), which extends perpendicular to the plane of the drawing. The mass scale 30 can be arranged, for example, on the end face of the shaft end or shaft shoulder.

[0055] As shown in FIG. 8, the second incrementally encoded code track 52 can be formed by the first incrementally encoded code track 36, so that the real measure 30 has two absolute encoded code tracks 34, 50 and one incrementally encoded code track.

[0056] 9 to 11 show various embodiments of a material scale 30, in particular having a first code section 32 and a second code section 48. In each of the embodiments shown in FIGS. 9 to 11, the first code section 32 and the second code section 48 can be arranged differently. In this case, the read head 10 and the material scale 30 can be arranged relative to each other so that a first sensor position p1 in the first code section 32 is detectable by the position sensor 1, and simultaneously a second sensor position p2 in the second code section 48 is detectable by the second position sensor 2. Since the first position sensor 1 and the second position sensor 2 are arranged at a fixed distance a from each other in the read head 10 (see also FIG. 1), the difference between the simultaneously detected sensor positions p1 and p2 varies between the material scales 30 shown in FIGS. 9 to 11. Therefore, the difference p1-p2 can be 6 in the embodiment shown in FIG. 9, 5 in the embodiment shown in FIG. 10, and 4 in the embodiment shown in FIG. 11.

[0057] 9 to 11, if the material scales 30 are arranged one behind the other, a measurement section having a length three times that of the material scale 30 can be realized. By differently differentiating the simultaneously detected sensor positions p1, p2 from each other in each material scale 30, each possible position of the read head 10 in the measurement section can be determined absolutely and unambiguously. In this case, in various embodiments of the material scale 30, in particular the same first code section 32 and / or the same second code section 48 are used.

[0058] According to this procedure, a measurement section can be created in which the number of successively arranged material scales 30 corresponds to the number of possible unique combinations of the first code section 32 and the second code section 48. If a material scale 30 of one meter in length has code sections 32, 48 that are absolutely coded to, for example, one micrometer, it is possible to obtain one million material scales 30 with differently arranged code sections 32, 48 by offsetting the code sections 32, 48. Thus, it is theoretically possible to create a measurement section with a total length of one million meters, i.e., 1,000 km.

[0059] In practice, the offset differences of the various material scales 30 will be in particular in the millimeter range in order to be able to determine an unambiguous sensor position p1, p1.1, p1.2, p2.1, p2.2 and therefore an unambiguous readhead position p, so that in the above example a measuring range of one kilometer can be realized. [Explanation of symbols]

[0060] 1 First position sensor 1.1 First position sensor 1.2 Second Primary Position Sensor 2 Second position sensor 2.1 First and second position sensors 2.2 Secondary position sensor 10 read head 12 Reading Direction 14 Sensor support 16 Read head housing 20 Encoder System 30 Actual meter 32 First Code Section 34 First Absolute Encoded Code Track 36 First Incremental Encoded Code Track 38 First Physical Measure Segment 40 Second Real Measure Segment 42 First segment end 44 Second Segment End 46 Gap 48 Second Code Section 50 Second Absolute Encoding Code Track 52 Second Incrementally Encoded Code Track 54 Ascending count direction 56 Descending count direction 58 Shaft 60 Shaft Radius a fixed distance a1 First fixed distance a2 Second fixed distance a3 Third fixed distance a4 Fourth fixed distance a5 Fifth fixed distance a6 Sixth fixed distance l Vertical p Reading head position p1 First sensor position p1.1 1st sensor position p1.2 Second first sensor position p2 Second sensor position p2.1 1st 2nd sensor position p2.2 Second sensor position q Horizontal

Claims

1. 1. An encoder system having the following features: a read head (10) having a first position sensor (1, 1.1, 1.2) and a second position sensor (2, 2.1, 2.2), said position sensors (1, 1.1, 1.2, 2, 2.1, 2.2) arranged at a fixed distance (a, a1, a2, a3, a4, a6, a6) from each other in the reading direction (12); a real measure (30) having a vertical direction (l) and a horizontal direction (q), the real measure (30) having a first code section (32) in the vertical direction (l) that includes a first absolute encoded code track (34); the read head (10) and the mass scale (30) are arranged relative to one another such that the reading direction (12) corresponds to the longitudinal direction (l), such that the read head (10) and the mass scale (30) are movable relative to the reading direction (12), and such that the first position sensors (1, 1.1, 1.2) can detect first sensor positions (p1, p1.1, p1.2) on the mass scale (30), and simultaneously such that the second position sensors (2, 2.1, 2.2) can detect second sensor positions (p2, p2.1, p2.2) on the mass scale (30); The encoder system further comprises a material scale (30) having a second code section (48), and the read head (10) and the material scale (30) are arranged relative to each other such that the first sensor positions (p1, p1.1, p1.2) in the first code section (32) can be detected by the first position sensors (1, 1.1, 1.2), and simultaneously the second sensor positions (p2, p2.1, p2.2) in the second code section (48) can be detected by the second position sensors (2, 2.1, 2.2).

2. the read head (10) comprises two first position sensors (1.1, 1.2) and two second position sensors (2.1, 2.2), The encoder system of claim 1 .

3. characterised in that the position sensors (1, 1.1, 1.2, 2, 2.1, 2.2) are formed as optical position sensors (1, 1.1, 1.2, 2, 2.1, 2.2).

3. The encoder system according to claim 1 or 2.

4. each of said position sensors (1, 1.1, 1.2, 2, 2.1, 2.2) is adapted to simultaneously scan an absolute encoded code track (34, 50) and an incremental encoded code track (36, 52); 3. The encoder system according to claim 1 or 2.

5. the position sensors (1, 1.1, 1.2, 2, 2.1, 2.2) are arranged on a one-piece sensor support (14) having a thermal expansion coefficient of numerically less than 2 ppm / K, 3. The encoder system according to claim 1 or 2.

6. the first code section (32) having a first incrementally encoded code track (34), 3. The encoder system according to claim 1 or 2.

7. The first cord section (32) and the second cord section (48) are arranged in opposite directions to each other.

3. The encoder system according to claim 1 or 2.

8. The substance measure (30) is characterized by having at least one substance measure segment (38, 40) including a first segment end (42) and a second segment end (44).

3. The encoder system according to claim 1 or 2.

9. The substance measuring device (30) is formed in a linear and / or arcuate and / or circular shape.

3. The encoder system according to claim 1 or 2.

10. the encoder system (20) comprises an evaluation unit for evaluating the sensor positions (p1, p1.1, p1.2, p2, p2.1, p2.2), the evaluation unit being configured to determine a read head position (p) from the simultaneously detected sensor positions (p1, p1.1, p1.2, p2, p2.1, p2.2), 3. The encoder system according to claim 1 or 2.

11. the evaluation unit is configured to check the sensor positions (p1, p1.1, p1.2, p2, p2.1, p2.2) for plausibility and / or convincingness and to not use implausible and / or inconvincing sensor positions (p1, p1.1, p1.2, p2, p2.1, p2.2) for determining the readhead position (p). The encoder system of claim 10.

12. the evaluation unit comprises storage means for storing the sensor positions (p1, p1.1, p1.2, p2, p2.1, p2.2) and / or the read head positions (p), The encoder system of claim 10.

13. The encoder system (20) has a plurality of real-world units (30), and the first code section (32) and the second code section (48) are arranged differently in each real-world unit (30).

3. The encoder system according to claim 1 or 2.

14. 3. A method for determining a readhead position (p) in an encoder system (20) according to claim 1 or 2, comprising the steps of: The encoder system (20) - simultaneously detecting first sensor positions (p1, p1.1, p1.2) of the first position sensors (1, 1.1, 1.2) and second sensor positions (p2, p2.1, p2.2) of the second position sensors (2, 2.1, 2.2); - checking the validity and / or plausibility of each sensor position (p1, p1.1, p1.2, p2, p2.1, p2.2) by comparison with each of the other simultaneously detected sensor positions (p1, p1.1, p1.2, p2, p2.1, p2.2); - determining the readhead position (p) based on the plausible and / or plausible sensor positions (p1, p1.1, p1.2, p2, p2.1, p2.2); The method comprises:

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