DEVICE AND METHOD FOR DETERMINING POSITION, LENGTH OR ANGLE, AND METHOD FOR FORMING A CORRESPONDING CODE

Abstract

Devices for determining position, length, or angle, comprising a first and a second part that are movable relative to each other. The first part is equipped with a code consisting of a multitude of first- and second-type code segments, where each combination of a predefined number of consecutive code segments forms a codeword of the code. The second part is equipped with a readout device comprising several sensors, each designed to detect the code segments and output a corresponding measured value. Finally, such devices also include an evaluation unit that determines a relative position between the first and second parts based on the measured values ​​detected by the readout device. The code may include a single track in which supposed word repetitions are indicated and / or triggered by a third-type code segment.The readout device can include more than the usual number of sensors to overscan the encoding. The encoding can also include a second track, which is marked with indicators that show word repetitions in the first track of the encoding. Furthermore, a corresponding method for determining position, length, or angle, and a method for generating a corresponding encoding, are described.

Description

[0001] The present invention relates to devices and methods for determining position, length, or angle, as well as methods for generating a corresponding coding. Reference is made to DE 102 01 496 A1, DE 10 2008 053 ​​977 A1, US 2022 / 0 260 365 A1, DE 10 2019 103 465 A1, and US 2004 / 0 118 758 A1 as prior art.

[0002] Corresponding devices conventionally comprise a first and a second part, which are movable relative to one another. A code comprising a plurality of code sections of the first and second type is attached to the first part, with each combination of consecutive code sections of a predefined number forming a code word of the code. A readout device is attached to the second part, which comprises a plurality of sensors, each configured to detect the code sections and output a corresponding measured value. Finally, such devices also comprise an evaluation unit, which determines a relative position between the first and second parts based on the measured values ​​detected by the readout device.

[0003] Such devices are also called encoders and can be used in a variety of technical fields. For example, such devices can be used in machine tools, enabling position or angle measurement of a tool relative to the workpiece. Other applications include rotary angle sensors and motor feedback systems.

[0004] Preferably, a number of code sections each form a code word. For example, code words can each consist of 4, 8 or 10 individual code sections, resulting in a 4-, 8- or 10-bit code. Each code word is preferably present only once in the coding, resulting in an absolute code or absolute coding. In particular, the size of the code sections and the size of the area of ​​the coding detected by individual sensors are selected such that exactly two sensors or at least two sensors detect a single code section, in particular when the code section lies exactly between the two sensors. In particular, the device comprises at least twice as many sensors as bits per code word, preferably four times as many sensors as bits per code word.

[0005] In order to reliably determine the relative position between the first and second parts, absolute coding, i.e., coding in which each codeword occurs only once, is regularly used. The range in which the relative position can be resolved depends on the length of the defined codewords as well as the length of the entire coding. For an coding consisting of two types of code sections with codewords of 5 bits in length, for example, the result is the value shown in the first line in Fig. 3. Each pattern of four consecutive code sections is unique along the entire coding. The size of the individual code sections, which is essentially determined by the design of the sensors used in the readout device, results in a certain minimum length for the absolute coding. However, there are situations, for example, in strictly regulated installation spaces, in which this minimum length is too long and the length of a 4-bit code is insufficient.

[0006] Consequently, it may be desirable to shorten the coding to adapt its overall length to the given requirements. As described, for example, in DE 10 2019 103 465 A1, not just any truncation results in a continued absolute coding, but only very specific truncations. This is particularly important for codings that form a closed loop, since a specific number of code sections at the beginning or end of the coding cannot simply be shortened to maintain the absoluteness of the coding.

[0007] In the second line in Fig. 3 shows an example of a specific shortening within the coding, which again leads to an absolute coding. In the third line in Fig. Figure 3 shows an example of a freely chosen shortening within the coding, which leads to a word repetition because word a and word b are now identical. Such a word repetition generally prevents the unambiguous determination of the relative position between the two parts.

[0008] Against this background, it is an object of the present invention to present solutions which enable the reliable resolution of relative movement using arbitrarily shortened originally absolute codings.

[0009] This object is achieved by each of the subject matters defined in the independent device and method claims.

[0010] According to a first variant of the present invention, the coding of the device described above comprises a first track with at least one word repetition and at least two words that each occur only once along the entire coding. Furthermore, the coding comprises a second track, which is provided with a marker at the level of each such word repetition. The evaluation unit is preferably designed to use the markers on the second track of the coding to distinguish between different relative positions between the first and second parts, which, in particular, would not be directly distinguishable from one another based solely on the first track.

[0011] To put it simply, to create the first track, an originally absolute coding is shortened at at least one location by any number of consecutive code segments, resulting in at least one word repetition in the coding. This shortening allows the length of the coding to be freely adapted to specific extrinsic requirements, such as the available space. In order to enable immediate differentiation of different relative positions despite the formation of word repetitions due to the shortening, the second track is provided. This second track contains markers that effectively indicate the locations of the shortenings and thus the locations of the formed word repetitions. These markers enable the evaluation unit to distinguish the locations of the formed word repetitions from the locations of the originally unambiguous words and thus to reliably distinguish the different relative positions from one another.It is essential that the markers on the second track are clearly identifiable, which means that a simple incremental track cannot function as the second track. Such a design is relatively simple to create overall, especially if only identical code sections of the first and second types are provided to form the two tracks.

[0012] Preferably, the markers are provided exactly at the level of the respective word repetition, before the respective word repetition and / or after the respective word repetition.

[0013] It is important that the evaluation unit is informed of the specific relative positioning in order to clearly identify the respective word repetitions. The easiest way to evaluate this is when the markers are positioned exactly at the level of the corresponding word repetitions. However, the relative positioning of the markers in front of and / or behind the respective word repetitions can also offer certain advantages.

[0014] In particular, there is only exactly one word repetition in the entire coding, meaning that exactly one codeword can occur twice. Furthermore, all other codewords (i.e., "words") in the coding can preferably only occur exactly once each.

[0015] Preferably, the second coding track is empty except for the designated markers. In other words, the second coding track generates changes in the associated measured values ​​only at the locations of the markers. Alternatively, the second track can be configured as an incremental track, in which the markers are formed by modified increments.

[0016] The first of these two alternatives is particularly easy to evaluate. The second of these two alternatives allows the simultaneous use of the incremental track to refine the triggering of the relative position in a known manner.

[0017] According to a second variant of the present invention, the coding of the device described above comprises at least one code section of a third type. The evaluation unit is designed to distinguish the code section of the third type from the code sections of the first and second type and, based thereon, to distinguish different relative positions between the first and second parts. The first track of the coding contains at least one word repetition and at least two words that each occur only once along the entire coding.

[0018] In this variant, word repetitions resulting from any shortening are distinguished by the provision of third-type code segments in the area of ​​the formed word repetitions. By resolving these third-type code segments, relative positions that would otherwise be indistinguishable from one another can be distinguished from one another, similar to the markers described above. This does not require a second track, as was the case with the first variant. Consequently, the second variant requires less space, but a more complex formation of the coding (with the third-type code segments) and evaluation of the measured values ​​(to identify the third-type code segments).

[0019] Preferably, the code sections of the third type are provided in, before, and / or after a code word which, without the distinction from the code sections of the first or second type, would occur at least twice in the coding.

[0020] In other words, the third-type code segments can each be provided within code words which, without these third-type code segments, would represent a word repetition resulting from any shortening of the coding. This effectively allows word repetitions to be avoided and thus the different relative positions to be immediately distinguishable. The positioning of the code segments before and / or after corresponding word repetitions can also be used by the evaluation unit to unambiguously identify the resulting word repetitions. This variant allows for free positioning of the third-type code segments along the coding, but requires more complex evaluation by the evaluation unit.

[0021] Preferably, the code sections of the third type and / or the markers each have the length of a single code section of the first and / or second type, or the length of several code sections of the first and / or second type.

[0022] The identical length of code sections or markers enables particularly simple evaluation of the measured values ​​from the readout device. By designing the third-type code sections or markers with a length that is a multiple of the length of the first-type and / or second-type code sections, the evaluation unit can handle the third-type code sections or markers as a plurality of code sections or markers of the same length as the first-type and / or second-type code sections, which is just as easy to evaluate.

[0023] According to a third variant of the present invention, the coding of the device described above is designed such that each combination of n consecutive code sections forms a code word of the coding. The coding contains at least one word repetition and at least two words that each occur only once along the entire coding. The readout device comprises at least 2*n+1 sensors.

[0024] Specifically, the coding and the reading device are coordinated such that, in any permitted relative position, each code section within the detection range of the sensors is within the detection range of at least two neighboring sensors. In addition, at least one additional sensor is provided, which extends the detection range. This results in oversampling of the coding and, based on the additional measured values, enables reliable determination of the relative position between the first and second parts, even if the originally absolute coding is no longer unambiguous due to a shortening of any length, i.e., if it contains at least one word repetition.

[0025] Preferably, the reading device comprises at least 2*n+2 sensors, preferably 2*n+2*m sensors, where m is a natural number greater than 1.

[0026] Specifically, the length of the evaluated codewords is preferably extended by m bits. This effectively leads to the determination of the relative position via appropriate oversampling using a non-unique encoding of n-bit codewords based on n+m-bit codewords, which are then unique. This allows the different relative positions to be clearly distinguished.

[0027] Preferably, two adjacent sensors are coupled via a differential circuit, which is designed to output a corresponding differential signal to the evaluation unit. The evaluation unit is designed to determine the relative position between the first and second parts, taking these differential signals into account.

[0028] Such a differential signal enables a rapid and reliable determination of the positions of transitions between contiguous areas of code sections of the first type and the second type within the detection range of the sensors. Taking this information into account, a more precise determination of the relative position between the first and second parts is possible without having to resort to additional coding, for example, in the form of an incremental track with an associated readout device.

[0029] Specifically, the device can initially read the absolute code in a conventional manner, in particular without the aforementioned subtraction, and in this way already detect a coarse position of the relative position. In addition, according to the invention, a fine position of the relative position can also be detected via subtraction. If, for example, it is determined during detection of the coarse position that a code section of the first type (e.g., a light area) lies "opposite" two sensors, the position of the code section can be detected even more precisely via subtraction. If, for example, an adjacent code section of the second type (e.g., a dark area) already extends into the detection range of one of the two sensors, the signal generated by this sensor is attenuated. Instead of a signal of, for example, "1," this sensor can then only deliver a signal of, for example, "0.8."As a result, the result of the differential circuit is not zero, but "0.2." The "position" of the edge, or more precisely, the transition between the different code sections, can therefore be determined more precisely. This makes it possible to determine that the relative position of the first and second parts does not exactly correspond to the coarse position, but should be corrected, for example, by 20% of the length of the area detected by a sensor. This can increase the accuracy of the position measurement.

[0030] Another advantage is that offset errors, which can be caused by thermal effects, for example, are minimized. The offset error usually affects both sensors connected to the differential circuit, thus eliminating the offset error during the difference calculation.

[0031] Another advantage is that for many positions of the coding, a higher amplitude is obtained after the difference calculation than when evaluating only one sensor. For example, with only one sensor and half of the area covered by a dark area, a signal with an amplitude of 50% would be present, whereas with the difference calculation, one sensor would deliver 100% amplitude and the other sensor 0%, resulting in an amplitude of 100% after the difference calculation.

[0032] Preferably, the detection range of each sensor on the associated coding track is half the width of the individual code sections of the associated coding track. Additionally or alternatively, the number of sensors provided in each set of sensors is at least twice the bit resolution of the associated track.

[0033] The bit resolution of a track is defined as the minimum number of consecutive code sections that must be resolved in order to make a clear, at least rough, determination of the relative position based on the respective track. Each of these two features results in an oversampling of the respective code track by the sensors of the readout device, which ultimately enables a more precise determination of the relative position between the first and second parts.

[0034] The sensors are preferably optical sensors, in particular photodiodes, magnetic sensors, capacitive sensors or inductive sensors.

[0035] For example, the sensors could be Hall sensors. These types of sensors are highly sophisticated and relatively inexpensive.

[0036] Preferably, the first and second parts are movable relative to each other either purely translationally or purely rotationally. The sensors provided are arranged next to each other, parallel to the coding.

[0037] If the coding has two different tracks, these are preferably parallel to each other. A purely translational or purely rotational relative movement is particularly easy to evaluate. The parallel arrangement of the sensors ensures an equal and constant distance between the sensors and the coding, thus facilitating the evaluation of the measured values.

[0038] Preferably, the code sections each have the same size and / or the same offset from one another.

[0039] Such symmetrical designs are particularly easy to form and evaluate.

[0040] In a method according to the invention for determining position, length, or angle, a first and a second part are moved relative to one another. A first track of a code comprising a plurality of first code sections of the first type and of the second type is previously applied to the first part, with each combination of consecutive code sections of a predefined number forming a code word of the code. A readout device having a plurality of first sensors attached to the second part detects the code, with the sensors each detecting the code sections and outputting a corresponding measured value. Finally, based on the detected measured values, a relative position between the first and second parts is determined.

[0041] The first coding track can be formed in such a way that it includes at least one word repetition and at least two words that each occur only once along the entire coding. Furthermore, a second coding track can be formed, which is provided with a marker at the level of each such word repetition. Finally, the markers on the second coding track are used to differentiate between different relative positions between the first and second parts, which would not be directly distinguishable from one another based solely on the first track.

[0042] This enables a reliable and unambiguous determination of the relative position between the first and the second part.

[0043] Alternatively, the coding can be formed in such a way that it comprises a code section of a third type, which is distinguishable from the code sections of the first and second type. Based on the code sections of the third type, different relative positions between the first and second parts are then distinguished from one another. The first track of the coding contains at least one word repetition and at least two words that each occur only once along the entire coding.

[0044] In other words, the provision of code segments serves to resolve word repetitions and thus distinguish between otherwise repetitive code words in the encoding. This allows the evaluation unit to unambiguously determine the relative position.

[0045] According to a further alternative, the coding can be formed such that each combination of n consecutive code sections forms a code word of the coding, wherein the coding comprises at least one word repetition and at least two words that each occur only once along the entire coding. The readout device used comprises at least 2*n+1 sensors.

[0046] The resulting oversampling of the coding enables a clear distinction between the different relative positions.

[0047] A method according to the invention for forming a code for one of the previously described devices or for a previously described method comprises forming and providing an absolute code using a conventional method. This code is then shortened at least at one point by any number of consecutive code sections, resulting in at least one word repetition in the code.

[0048] According to the invention, the coding is specifically formed with a first track containing at least one word repetition and at least two words that each occur only once along the entire coding, and a second track provided with a marker at the level of each such word repetition. Using the markers on the second track of the coding, different relative positions between the first and second parts, which would not be directly distinguishable from one another based solely on the first track, can be distinguished from one another.

[0049] The markers on the second track enable the identification of formed word repetitions and, based on this, the differentiation of different relative positions.

[0050] Alternatively, the coding is formed with at least one code section of a third type, which is distinguishable from the code sections of the first and second types. Based on the code sections of the third type, different relative positions between the first and second parts can be distinguished from one another.

[0051] This means that a second track with markers can be dispensed with in order to save installation space, but this requires increased evaluation effort.

[0052] The above explanations regarding the device according to the invention apply accordingly to the method according to the invention. This applies in particular to advantages and embodiments.

[0053] The invention is described below by way of example with reference to the drawings, in which: Fig. 1 a schematic view of the basic structure of an exemplary device for determining position or length, which is to be further developed according to the invention; Fig. 2 a schematic view of a further development of the device from Fig. 1; Fig. 3 schematically shows the problem underlying the invention; Fig. 4 schematically shows three inventive approaches to solving the problem of Fig. 3; and Fig. 5 schematically shows a further approach to the inventive solution of the problem from Fig. 3.

[0054] In the figures, the same reference symbols denote the same or similar features.

[0055] Fig. Figure 1 schematically shows the structure of a device 10 according to the invention for determining position or length. The device 10 shown serves as an encoder, for example, in a motor feedback system (not shown).

[0056] The device 10 comprises a first part 14, to which an absolute coding 12 is attached. The device 10 further comprises a second part 18, to which a readout device 16 is attached. The coding 12 and the readout device 16 are fastened to the first part 14 and the second part 18 in such a way that they move relative to one another together with the two parts 14 and 18. In the present example, the first part 14 and the second part 18—and thus the coding 12 and the readout device 16—are movable relative to one another purely in a translational manner (see the double arrow B). Purely rotational relative movements can also be easily implemented by a person skilled in the art.

[0057] The coding 12 is formed by a plurality of consecutive code sections 22-0 to 22-9 of the first type (shown in white) and the second type (shown in black). Fig. 1, only ten such code sections 22-0 to 22-9 are depicted. The coding 12 can comprise additional code sections to the left and / or right of the depicted code sections 22-0 to 22-9. This would allow the relative position between the two parts 14 and 18 to be determined over a larger range than would be possible with the ten depicted code sections 22-0 to 22-9.

[0058] The reading device 16 comprises eight sensors 20-1 to 20-8, for example in the form of photodiodes, wherein the sensors 20-1 to 20-8 are arranged side by side parallel to the coding 12. The sensors 20-1 to 20-8 are aligned with the coding 12 and are designed to detect the different code sections 22-0 to 22-9 of the coding 12.

[0059] For uniform illumination of the code sections 22-0 to 22-9, a light source (not shown) can be provided, which illuminates at least those code sections 22-0 to 22-9 that lie within the detection range of the sensors 20-1 to 20-8 (the area between the two dashed-double-dotted arrows). Each of the sensors 20-1 to 20-8 receives – depending on the type of code sections 22-0 to 22-9 in its detection range – a specific amount of light reflected or transmitted by the respective code sections 22-0 to 22-9. The sensors 20-1 to 20-8 then output a corresponding measured value, for example in the form of a voltage or current value.

[0060] To facilitate the evaluation of the measured values ​​of sensors 20-1 to 20-8, the code sections 22-0 to 22-9 are spatially identical to each other. It is assumed here that the detection range of each sensor 20-1 to 20-8 is half as wide as the individual code sections 22-0 to 22-9 are long. The sensors 20-1 to 20-8 are aligned with the coding 12 in such a way that they form a continuous detection range (see the area between the dashed-double-dotted arrows in Fig. 1) on the coding 12, the length of which corresponds exactly to the length of a code word of the coding 12. In other words, each code section 22-4 to 22-6, which lies entirely within the detection range of the sensors 20-1 to 20-8, is located within the detection range of at least two, in particular three, adjacent sensors 20-1 to 20-8. This enables particularly fine scanning of the coding 12 and thus a particularly precise resolution of the relative position between the first part 14 and the second part 18.

[0061] The sensors 20-1 to 20-8 are followed by differential circuits 26-1 to 26-7 and an evaluation unit 24.

[0062] In this case, these differential circuits 26-1 to 26-7 are preferably each designed analogously and are coupled on the input side to two adjacent sensors 20-1 to 20-8, which output analog measured values ​​to the differential circuits 26-1 to 26-7 (see also the illustration in Fig. 2).

[0063] Each of the differential circuits 26-1 to 26-7 is configured to calculate a difference between the obtained measured values ​​and output it as a differential signal to the evaluation unit 24. Based on these differential signals, the evaluation unit 24 can reliably and precisely identify and locate the position of the transitions between regions of consecutive code sections of the first type 22-0, 22-2, 22-4, 22-5, and 22-9, and consecutive code sections of the second type 22-1, 22-3, and 22-6 to 22-8. Specifically, the differential signal of two adjacent sensors exhibits a peak whenever a transition between regions of code sections 22-0 to 22-9 of different types moves from the detection range of one sensor into the detection range of the adjacent second sensor.Consequently, it is possible to determine precisely, in a relatively simple and reliable manner, the location of the transitions between the contiguous areas of code sections of the same type in relation to the detection ranges of the sensors. From this, the relative position between the first part and the second part can be determined very precisely, taking into account the type of the respective areas of the code sections. This eliminates the need for additional coding, for example, in the form of a separate incremental track with an associated readout device.

[0064] As in Fig. 2, each of the differential circuits 26-1 to 26-7 can further be followed by a comparator 28-1, 28-2, or 28-3. Each of these comparators 28-1 to 28-3 can further be connected on the input side to a reference unit REF and can be designed to compare the differential signal received from the associated differential circuit 26-1 to 26-7 with a reference signal received from the reference unit REF. A comparison signal generated therefrom, in particular a binary one, is then output to the evaluation unit 24 for analysis. In other words, the differential values ​​are not digitized based on a single fixed threshold value, as is usual, but rather based on a varying threshold value. If the reference signal varies sufficiently quickly, each differential value is effectively binarized based on a plurality of different threshold values.The evaluation unit 24 can then more precisely reconstruct the specific form of the difference signal based on the corresponding comparison signal and thus more precisely determine the positions of the transitions in the detection range of the sensors 20-1 to 20-8 as well as the corresponding relative position between the first part and the second part. In doing so, the reference unit generates, in particular, a time-varying, preferably periodically repeating, reference signal.

[0065] To put it figuratively, in the first comparator 28-1, an analog difference value from the first difference circuit 26-1 can be compared with, for example, three different reference values ​​specified by the reference signal. Assume a first difference value is 80% and the three reference values ​​defined by the reference signal are 25%, 50%, and 75%. The comparator 28-1 then outputs a "111" to the evaluation unit 24 as a binarized comparison signal for the first difference value, since the first difference value is higher than all three reference values. From this, the evaluation unit 24 can conclude that the difference value and thus the associated coverage is at least 75%. In the case of a second difference value of, for example, 60%, the binarized comparison signal would correspond to a "110."From this, the evaluation unit 24 can conclude that the second difference value and thus the corresponding coverage lies between 50% and 75%. This allows the evaluation unit 24 to distinguish between the situations of the two exemplary difference or coverage values ​​of 80% and 60%. Based on this, the evaluation unit can more precisely determine the positions of the transitions and thus the relative position between the first and second parts. In a conventional design with a fixed comparison value of, for example, 50%, this distinction would not be possible, since the evaluation unit 24 cannot resolve any difference in the binarized signal. The binarized signal would simply display a "1" for both difference values.

[0066] As an alternative to discrete comparison signals, the comparison signal can also be changed continuously, whereby the currently applied comparison signal is determined when the comparator is switched.

[0067] It is possible to use a predefined periodic reference signal or to have the evaluation unit 24 specify the exact shape of the reference signal in order to be able to determine the positions of the transitions with particular precision, particularly iteratively. Specifically, if the reference signal is controlled by the evaluation unit 24, the evaluation unit 24 could increase the reference value for a binarized value of 1 and decrease the reference value for a binarized value of 0 until the exact difference value is determined with sufficient accuracy. Of course, with such a functionality, it is also conceivable to supply the different comparators with specific reference signals. This makes the evaluation of the difference values ​​more complicated, but also more efficient and accurate.

[0068] It is understood that the device 10 described here can also be replaced by magnetic, capacitive, or inductive sensors and a corresponding coding 12 as an alternative to optical sensors 20-1 to 20-8 and an optical coding 12. A person skilled in the art will also be able to devise numerous modifications and deviations from the described embodiments, which are probably not explicitly described here but nevertheless fall within the scope of the claims.

[0069] In the following, with reference to the Fig. 4 and Fig. 5 different inventive approaches to solving the problems mentioned at the beginning with regard to Fig. The problem described in section 3 is presented.

[0070] According to the first line in Fig. 4 it is possible to extract the two words a and b from Fig. 3 distinguishable by replacing one of the code sections of the first or second type in the word repetition formed by the abbreviation (i.e., in word a) with a code section of a third type. The resolution of this code section of the third type by the readout device and the evaluation unit enables a direct differentiation of the words a and b. This allows a clear determination of the relative position between the two parts without the need for an additional coding track.

[0071] In the second line of the Fig. 4, as an alternative to the code section of the third type, a second predominantly empty track is provided next to (or below) the first track of the coding (with the two identical words a and b). The second track only includes a marker at the level of the shortening made and thus at the level of the word repetition (i.e., at the level of word a). The detection and identification of this marker allows the differentiation of the two relative positions in which one of the two identical words a and b lies within the detection range of the sensors. In general, at least one additional sensor is provided for detecting the second track, which sensor outputs a signal to the evaluation unit 24, in particular, only at the level of the marker and thus at the level of the formed word repetition.

[0072] In the further alternative of the third line in Fig. 4, the second track is not a predominantly empty track, but an incremental track, which has a marker in the form of a modified increment at the level of the formed word repetition. While the incremental track can be formed from an alternating sequence of code sections of the first and second type, it is possible to form the marker by replacing a code section of one type with a code section of the other type. This variant is shown in Fig. 4. To resolve such a marker, it is necessary to scan the incremental track with one or more sensors that form a combined detection range that extends beyond the length of a single code section. Otherwise, the marker would be indistinguishable from a simple increment. Alternatively, the marker can be configured analogously to the design shown in the first line of the Fig. 4 may also be formed by a code section of a third type in order to be able to distinguish it directly from simple increments.

[0073] While the first variant, with only one track and code sections of a third type, can be created very compactly, the two variants with markers on a second track are particularly flexible and easy to evaluate. The variant with the modified incremental track as the second track offers the possibility of increasing the accuracy of determining the relative position between the two parts.

[0074] Fig. Figure 5 schematically shows another variant based on the approach of oversampling the shortened coding by providing additional sensors.

[0075] The scanning of a code consisting of 5-bit code words is preferably carried out with ten sensors (i.e. twice as many sensors as the individual code words have bits), each of which covers an area on the code that is half as long as the individual code sections. This enables the reliable and precise determination of the respective 5-bit code word that lies within the detection range of the reading device for a specific relative position. In the case of an absolute code, in which each code word occurs only once, this is sufficient for the reliable and precise determination of the relative position, but not in the case of codes with at least one word repetition. Such word repetitions, however, regularly arise from arbitrary shortening of the code, as described above with regard to Fig. 3 was described.

[0076] To be able to resolve these word repetitions without further adjustment of the coding and / or the provision of a second coding track with associated sensors, at least one additional sensor is provided, preferably m times 2 additional sensors, where m is a natural number greater than or equal to 1. These additional sensors are also designed to detect the coding. They can be connected directly to the other sensors or located at a distance from them.

[0077] In the example of Fig.5, for example, the ten sensors already provided are supplemented by a pair of additional sensors. These additional sensors are designed in such a way that they seamlessly extend the detection range of the remaining 10 sensors. This effectively results in the coding consisting of 5-bit code words (which are no longer unique due to the shortening) being evaluated as if it were a coding of 6-bit code words. This effectively no longer resolves the two code words a and b, but rather the code words a1, a2, b1, and b2. While the code words a and b are still identical to one another, this does not apply to the code words a1, a2, b1, and b2. Based on this difference, the evaluation unit can distinguish between a relative position in which word a lies within the detection range of the sensors and a relative position in which word a lies within the detection range of the sensors.

[0078] Finally, it should be noted that the present invention also encompasses corresponding methods for determining position, length, or angle, as well as methods for generating a corresponding coding. A person skilled in the art can devise numerous modifications and combinations of the described approaches based on the above description and the presented embodiments. Even if not every such modification or combination has been explicitly described, they may nevertheless fall within the scope of the claims. List of reference symbols 10 Device for determining position, length or angle 12 Coding 14 first part 16 Reading device 18 second part 20-1 to 20-8 sensors 22-0 to 22-9 code sections 24 evaluation unit 26-1 to 26-7 differential circuits 28-1 to 28-3 Comparators a, b 5-bit long codewords a1, a2 6 Bit long Codewörter b1, b2 6 Bit long Codewörter REF Referencesinheit

Claims

[1] Device (10) for determining position, length or angle, comprising: - a first and a second part (14, 18) which are movable relative to each other, - a code (12) attached to the first part (14) with a first track consisting of a plurality of successive code sections (22-0 to 22-9) of the first type and of the second type, each combination of successive code sections (22-0 to 22-9) of a predefined number forming a code word of the code (12), - a reading device (16) attached to the second part (18) for detecting the coding (12), wherein the reading device (16) comprises a plurality of sensors (20-1 to 20-8), each of which is designed to detect the code sections (22-0 to 22-9) and output a corresponding measured value, and - an evaluation unit (24) which determines a relative position between the first and the second part (14, 18) on the basis of the measured values ​​recorded by the reading device (16), characterized by , that the first track of the coding (12) contains at least one word repetition and at least two words which each occur only once along the entire coding (12), wherein the coding (12) contains a second track which is provided with a marker at the level of each such word repetition, wherein the evaluation unit (24) is designed to distinguish, on the basis of the markers on the second track of the coding (12), different relative positions between the first and the second part (14, 18), which would not be directly distinguishable from one another based on the first track alone. [2] Device (10) according to the preceding claim 1, characterized bythat the markers are positioned exactly at the level of the respective word repetition, before the respective word repetition and / or after the respective word repetition. [3] Device (10) according to one of the preceding claims, characterized by , that the second track of the coding (12) is empty except for the designated markers, or the second track is designed as an incremental track in which the markers are formed by modified increments. [4] Device (10) for determining position, length or angle, comprising: - a first and a second part (14, 18) which are movable relative to each other, - a coding (12) attached to the first part (14) comprising a plurality of successive code sections (22-0 to 22-9) of the first type and of the second type, each combination of successive code sections (22-0 to 22-9) of a predefined number forming a code word of the coding (12), - a reading device (16) attached to the second part (18) for detecting the coding (12), wherein the reading device (16) comprises a plurality of sensors (20-1 to 20-8), each of which is designed to detect the code sections (22-0 to 22-9) and output a corresponding measured value, and - an evaluation unit (24) which determines a relative position between the first and the second part (14, 18) on the basis of the measured values ​​recorded by the reading device (16), wherein the coding (12) has at least one code section of a third type and the evaluation unit (24) is designed to distinguish the code section of the third type from the code sections of the first and second type and, based thereon, to distinguish different relative positions between the first and the second part (14, 18) from one another, characterized by that the first track of the coding (12) contains at least one word repetition and at least two words which each occur only once along the entire coding (12). [5] Device (10) according to the preceding claim 4, characterized bythat the code sections of the third type are provided in, before, and / or after a code word which, without the distinction from the code sections of the first or second type (22-0 to 22-9), would occur at least twice in the coding (12). [6] Device (10) according to one of the preceding claims, characterized by that the code sections of the third type and / or the markers each have the length of a single code section of the first and / or second type, or have the length of several code sections of the first and / or second type. [7] Device (10) for determining position, length or angle, comprising: - a first and a second part (14, 18) which are movable relative to each other, - a coding (12) attached to the first part (14) comprising a plurality of successive code sections (22-0 to 22-9) of the first type and of the second type, each combination of n successive code sections (22-0 to 22-9) forming a code word of the coding (12), - a reading device (16) attached to the second part (18) for detecting the coding (12), wherein the reading device (16) comprises a plurality of sensors (20-1 to 20-8), each of which is designed to detect the code sections (22-0 to 22-9) and output a corresponding measured value, and - an evaluation unit (24) which determines a relative position between the first and the second part (14, 18) on the basis of the measured values ​​recorded by the reading device (16), characterized bythat the coding (12) contains at least one word repetition and at least two words which each occur only once along the entire coding (12), wherein the reading device (16) comprises at least 2*n+1 sensors. [8] Device (10) according to the preceding claim 7, characterized by that the reading device (16) comprises at least 2*n+2 sensors, preferably 2*n+2*m sensors, where m is a natural number greater than 1. [9] Device (10) according to one of the preceding claims, characterized by , that two adjacent sensors (20-1 to 20-8) are coupled via a differential circuit which is designed to output a corresponding differential signal to the evaluation unit (24), wherein the evaluation unit (24) is designed to determine the relative position between the first and the second part (14, 18) taking these difference signals into account. [10] Device (10) according to one of the preceding claims, characterized by that the detection range of each sensor (20-1 to 20-8) on the coding (12) is half as wide as the individual code sections (22-0 to 22-9), and / or the number of sensors in each set of sensors (20a, 20b) is at least twice as large as the bit resolution of the respective track. [11] Device (10) according to one of the preceding claims, characterized by that the sensors are optical sensors, in particular photodiodes, magnetic sensors, capacitive sensors or inductive sensors. [12] Device (10) according to one of the preceding claims, characterized by , that the first and second parts (14, 18) are movable relative to each other either purely translationally or purely rotationally, wherein the sensors provided (20-1 to 20-8) are each arranged next to one another parallel to the coding (12). [13] Device (10) according to one of the preceding claims, characterized by that the code sections (22-0 to 22-9) each have the same size and / or the same offset from one another. [14] Method (100) for determining position, length or angle, in which - a first and a second part (14, 18) are moved relative to each other, - a code (12) having a first track comprising a plurality of code sections (22-0 to 22-9) of the first type and of the second type is applied to the first part (14), each combination of successive code sections (22-0 to 22-9) of a predefined number forming a code word of the code (12), - a reading device (16) detects the coding (12), wherein the reading device (16) comprises a plurality of sensors (20-1 to 20-8) attached to the second part (18), which are each designed to detect the code sections (22-0 to 22-9) of the first track and output a corresponding measured value, - a relative position between the first and the second part (14, 18) is determined on the basis of the measured values, characterized by , that a) the coding (12) is formed in such a way that the first track contains at least one word repetition and at least two words, each of which occurs only once along the entire coding (12), and comprises a second track which is provided with a marker at the level of each such word repetition, wherein, based on the markers on the second track of the coding (12), different relative positions between the first and the second part (14, 18), which would not be directly distinguishable from one another based on the first track alone, are distinguished from one another; or b) the coding (12) is formed with at least one code section of a third type, which is to be distinguished from the code sections of the first and second type, wherein different relative positions between the first and the second part (14, 18) are distinguished from one another based on the code sections of the third type, wherein the first track of the coding (12) contains at least one word repetition and at least two words, each of which occurs only once along the entire coding (12); or c) the coding (12) is formed such that each combination of n consecutive code sections (22-0 to 22-9) forms a code word of the coding (12) and the coding (12) comprises at least one word repetition and at least two words which each occur only once along the entire coding (12), wherein a readout device (16) with at least 2*n+1 sensors is used to detect the coding. [15] A method (100) for forming a code (12) for the device of any one of claims 1 to 13 or a code (12) for the method of claim 14, comprising: Forming and providing a single-track absolute coding (12) by means of a conventional method; Shortening the coding (12) at at least one point of the coding (12) by any number of consecutive code sections (22-0 to 22-9), characterized by , that a) the coding (12) is shortened in such a way that it comprises at least one word repetition and at least two words which each occur only once along the entire coding (12), wherein the coding (12) is supplemented by a second track which is provided with a marker at the level of each such word repetition, wherein, based on the markers on the second track of the coding, different relative positions between the first and the second part (14, 18), which would not be directly distinguishable from one another based on the first track alone, can be distinguished from one another; or b) the coding (12) is supplemented by at least one code section of a third type which is distinguishable from the code sections of the first and second type, wherein different relative positions between the first and the second part (14, 18) are distinguishable from one another based on the code sections of the third type.

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