EP1412274B1 - Lift system comprising a measuring system for determining the absolute position of the cage - Google Patents

Abstract

An elevator car position measuring system includes a strip having a code mark pattern mounted near the elevator car and parallel to a travel direction, a code reading device mounted on the elevator car for contactless scanning of the code mark pattern and an evaluating unit connected to the code reading device for evaluating the scanned code mark pattern. A code word is formed by "n" successive code marks of the code mark pattern, a plurality of different ones of the code words are unambiguously arranged in an n-digit pseudo random sequence, the code words form a single-track of the code mark pattern and each of the code words represents an absolute car position. A floor sensor mounted on the elevator car detects position markings at floor levels along the travel direction and is connected to the evaluating units for evaluating the detected position markings against said scanned code words.

Description

The invention relates to an elevator installation with a measuring system for determining the absolute cabin position of an elevator car which can be moved along at least one guide rail according to the definition of the patent claims.

In elevators, the position information in coded form is fixedly mounted along the entire travel path of the elevator car and is read by means of a code reading device in coded form and forwarded to an evaluation unit. The evaluation device prepares the read encoded position information in a way that is understandable and derives therefrom information signals that are forwarded as so-called shaft information for the elevator control.

From the DE 42 09 629 A1 For example, a high resolution absolute measuring system is known for determining the relative position of two relatively movable parts. In the hitherto customary manner, an absolute code mark pattern in the form of a gapless sequence of identically long code marks of a pseudorandom coding and in a second track parallel thereto an incremental code character pattern are formed there on a first part in a first track. Any n consecutive code marks represent a code word in the absolute code mark pattern. Each of these code words occurs only once in the entire code mark pattern. On a first part relatively movable second part of a code reading device is provided, which in the direction of movement n successive Can detect code tags at once while scanning the incremental code character pattern. If the code reading device travels around a code mark position of the absolute code mark pattern along the first part, then a new n-digit binary code word is already read.

In this known device, each code word of the absolute code mark pattern defines a certain relative position of both parts to one another. The length of the individual code marks measured in the direction of movement or reading and the number of maximum possible code words determine the maximum length of the measuring path which can be addressed with codewords. The resolving power with which the relative position expressed in the pseudo-random code, the so-called position code, can be measured depends on the length of each individual code mark. The smaller the length of the code marks, the more accurate positioning can be. However, reading becomes progressively more difficult with decreasing length of the code marks, especially at high relative speeds.

In an application of such an absolute length measuring system for determining the position of an elevator car, such as the known from German Utility Model G 92 10 996.9 elevator, the entire track in the direction of travel of the elevator car is complete with coded position information to address the code words of pseudo-random coding. However, the maximum of the measuring or travel path is limited by the sum of the lengths of all code marks. For long distances, therefore, a pseudo-random coding with multi-digit code words and / or code marks with longer lengths is provided. However, multi-digit code words require correspondingly complex code reading devices and evaluation units, which is associated with high costs. As the length of the individual code marks increases, however, the resolving power decreases.

Another length measuring systems is from the US-A-5135081 known.

In order to avoid reading errors, the absolute code mark pattern and the incremental code character pattern are to be displayed in their relative position exactly aligned with one another. This makes the production of a two-track code carrier expensive and on the other hand requires a time-consuming accurate assembly. In addition, in particular the code reading device of a two-lane absolute position measuring system builds large, which is undesirable in view of limited available shaft cross-sectional area. Moreover, the traversing speed is limited in the case of two-lane measuring systems, which is perceived as limiting, in particular, in elevators with large delivery heights.

The object of the invention is to provide an elevator described above with a measuring system for determining the absolute position of the elevator car, which allows a high resolution in the position detection with the least possible effort over a long trajectory of the elevator car.

The solution to this problem is inventively given by an elevator with an absolute position measuring system with the features of claim 1, which is particularly characterized in that the absolute code mark pattern and the incremental code character pattern are shown as a single-track combined code mark pattern of n-digit pseudorandom sequence in Manchester encoding and the code reading device comprises sensors for sampling n + 1 consecutive code marks, each sampling the second code mark of the single-track combined code mark pattern. The essence of the invention consists of a single-lane coding for an absolute length measuring system in which, starting from a binary n-digit pseudo-random sequence, which encodes 2 ⁿ -1 different position values, a 0 is inserted behind every 0 and every 1 behind. The double-length sequence thus obtained according to the invention represents a quasi combination of n-digit pseudorandom coding and Manchester coding. In order for all code words occurring in the combined code mark pattern to differ from one another, n + 1 code marks of the respective second code marks of the combined code mark pattern must be scanned.

With the coding according to the invention, the advantages of absolute single-track systems can be combined with the advantage of the high resolution of absolute two- or multi-track systems.

With the combination of the invention combined with an n-digit pseudorandom coding with unchanged resolution, a twice as long measuring distance can be displayed as that which corresponds to the sum of the lengths λ of all code marks of the n-digit pseudorandom coding from which it is derived. In this case, in the single-track combined code mark pattern according to the invention, only individual code marks with the length λ and code marks of the length occur 2λ up. Consequently, a code mark change takes place at the longest after the length of 2λ, which can be detected or scanned by means of the code reading device. From the quasi-equidistant code mark changes a scanning signal is derived, with which the sensors are controlled for detecting the single-track Postionscodes. The reading always takes place when the sensors are completely in coverage of the code marks to be read. The single-lane code mark pattern is slim and therefore requires only a small attachment surface along the travel distance. In addition, a single-track code carrier is easy and inexpensive to produce.

With only one additional reading point of the code reading device more, that is, only n + 1 reading points, a unique or absolute pattern of characters can be read on the track of the combined code mark pattern according to the invention.

The code reading device with only n + 1 reading points according to the invention is inexpensive and has a comparatively small size compared to conventional code reading devices for the same travel path and comparable resolution. To read the single-track combined code mark pattern, the sensors are arranged in the direction of movement on a line at a mutual distance of 2λ, whereby the code reading device builds slim and can be arranged to save space laterally next to the guide rail movable.

In a simple way can already at startup without moving the elevator car, its absolute position be determined by two sensors are arranged in the direction of travel at a distance of half the code mark length for each bit of the combined code mark pattern. If one of the two sensors is in the vicinity of a code mark change and supplies a sensor voltage of approximately zero, then the other sensor is certainly in coverage to a code mark and provides secure information. In each case the first sensors and in each case the second sensors for absolute reading are combined to form a sensor group. Of the two intermeshing sensor groups offset by half the code mark length, only the output signals of the sensors from one of the two sensor groups are alternately selected and evaluated for reading. The changeover to the respectively correct one of the two sensor groups takes place via the determination of the position of the transition between two different code marks and the two sensor groups by the scanning signal.

When using the single-track combined coding according to the invention in a magnetic measuring system, the suppression of small magnetic poles by adjacent large magnetic poles, the so-called intersymbol interference, is reduced. This has a positive effect on the reading reliability with a greater distance of the code reading device to the code mark pattern. The distance of the code reader to the combined code mark pattern can thus be selected larger in a magnetic measuring system. Thus, the measuring system wengier vulnerable to contamination of the code carrier and occurring relative movements of the code reader relative to the code mark pattern in the direction perpendicular to the reading or traversing the car. The uniform Length of the code marks also allows a quick evaluation by inexpensive parallel working components.

In a preferred embodiment as a magnetic measuring system, only simple and inexpensive Hall sensors are used to scan the linear position code. Hall sensors also serve for an interpolation device for determining the position of the transition between two different code marks - the zero crossing of the magnetic field - relative to the sensor strip. The interpolation device is arranged in the direction of travel over an area with a length greater than the length of two code marks 2λ. The distance between these Hall sensors is smaller than the length λ of a code mark.

Furthermore, it is provided in a particularly preferred embodiment of the invention, in addition to the Hall sensors to use an MR sensor with which scans the inventive coding and thus the resolution compared to previous absolute Einspursystemen is significantly increased. Due to the described properties, a combined code mark pattern with magnetic code marks outwards forms a magnetic field with a profile which is composed of approximately sinusoidal half-waves. These halfwaves each have the length λ or the length 2λ of two code marks. When scanning with a corresponding MR sensor can be generated by arctangent interpolation of the sensor voltages, a high-resolution position value, which is wegproportional each within a pole. Combined with the absolute position value with the resolution a code mark length results in a high-resolution absolute position.

A particularly reliable measuring system for determining the absolute cabin position can be obtained by designing the code reading device to scan the position code, including the evaluation unit, in a redundant manner. The second code reading device is basically the same as the first code reading device and differs only by an arrangement of the intermediate reading unit and the fine interpolation in this order in the traversing direction behind the position code reading unit. The sensor pairs of both position code reading devices are in a line parallel to the reading direction, offset by a code mark length from each other and arranged intermeshing. The code reading device is of compact construction and only longer by the interpolation device and the fine interpolation device than in a non-redundant measuring system.

Each of the two code reading devices is assigned its own evaluation unit, so that the output signals of the sensors of both code reading devices are evaluated independently of one another and are available for controlling the elevator.

The redundant design of the single-track measuring system also meets applicable safety requirements in the elevator industry and thus opens up the possibility to replace the previously mechanically executed safety devices by electrical. Furthermore, she is in common with in each case one floor sensor for each of the two measuring systems, the basis of a comprehensive shaft information system, which is shown schematically in FIG Fig. 7 is shown. Each evaluation unit is assigned to one of the floor sensors. The floor sensors are moved together with the elevator car in the shaft to detect in the shaft at each floor level arranged position markers. These signals are processed together with the output signals of redundant provided safety devices together with the position information and serve to control the elevator system.

Fig. 1,

schematisch eine Aufzuganlage mit einer Einrichtung zur Ermittelung der Position einer Aufzugkabine;

Fig. 2,

schematisch den Aufbau einer ersten Ausführung der Erfindung;

Fig. 3,

die Anordnungsreihenfolge der einzelnen Bits im kombinierten Codemarkenmuster,

Fig. 4,

eine zweite Ausführung der Codelesesensorik;

Fig. 5,

ein Verlauf des Ausgangssignals der Interpolationseinrichtung,

Fig. 6,

den Verlauf des Ausgangssignals eines MR- Winkelsensors der Feininterpolation bei Abtastung des Magnetfeldverlauf über dem codierten Magnetband,

Fig. 7,

eine zweite redundante Ausführung des Messystem gemäss der Erfindung.

Fig. 8

eine redundante Ausbildung des einspurigen Messsystems als Grundlage eines umfassenden Schachtinformationssystems.

Further features and advantages of the invention will become apparent from the following description of a preferred embodiment with reference to the accompanying drawings. It shows:

Fig. 1,

schematically an elevator system with a device for determining the position of an elevator car;

2,

schematically the structure of a first embodiment of the invention;

3,

the arrangement order of the individual bits in the combined code mark pattern,

4,

a second embodiment of the code reading sensor;

Fig. 5,

a profile of the output signal of the interpolation device,

6,

the course of the output signal of an MR angle sensor of the fine interpolation when scanning the magnetic field profile over the coded magnetic tape,

Fig. 7,

a second redundant embodiment of the measuring system according to the invention.

Fig. 8

a redundant design of the single-track measuring system as the basis of a comprehensive shaft information system.

At the in Fig. 1 schematically shown elevator with a shaft 1, an elevator car 2 and a counterweight 3 are suspended on a plurality of support cables, of which here a representative support cable 4 is shown. The support cables 4 run over a deflection roller 5 and are guided by a driven traction sheave 6. The traction sheave 6 transmits the driving forces of a drive motor, not shown here, to the supporting cables 4 driven by it for lifting and lowering the counterweight 3 and the elevator car 2 along a guide rail 7. Guiding shoes 9 fixedly connected to the elevator car 2 in the travel direction 8 serve to guide the elevator car 2 in the direction perpendicular to the direction of travel 8 on the guide rail 7. On the guide rail 7 is a magnetic tape 10 along the entire route of the elevator car 2 parallel to the direction of travel 8 of the elevator car 2 attached stationary. The magnetic tape 10 serves as a carrier for a single-track combined code mark pattern according to the invention, which represents the numerical code of absolute positions of the elevator car 2 in the shaft 1 relative to a zero point.

A code reading device 12 is fixedly mounted on the elevator car 2 in the direction of travel 8. It consists essentially of a code reading sensor 11 carrying sensor block 13 which is supported by a holder 14 perpendicular to the direction of travel 8 verschiebar. A roller guide 15 guides the sensor block 13 on the guide rail 7 when the code reader 12 is in common is moved with the elevator car 2. The same arrangement is also possible laterally or at the bottom of the elevator car 2.

The code reading device 12 transfers the read coded information via connecting lines 16 to an evaluation unit 17. The evaluation unit 17 translates the read coded information into a binary expressed absolute position information understandable to the elevator control 18 before being transmitted via a suspension cable 19 to the elevator control 18, for example for positioning the elevator car 2 is forwarded.

Fig. 2 schematically shows a first embodiment of the invention with a magnetic measuring system. On a portion of the guide rail 7, a magnetic tape 10 having a single-track combined code mark pattern 20 is mounted. The code marks 21 are symbolized by arranged in a longitudinal direction of the magnetic tape 10 in a track equal length rectangular sections with a length of λ = 4 mm and magnetized either as a magnetic north pole 22 or magnetic south pole 23. The individual north poles 22 and south poles 23 form correspondingly oriented magnetic fields to the outside. Each two adjacent code marks 12 define a so-called bit of coding. If a north pole 23 is located in the travel direction 8 in front of a south pole 23, this bit is assigned the value "0", while the value "1" is assigned to a south-north transition. This type of significance of the bits defined by state changes is known as so-called Manchester coding. By way of illustration, in Fig. 2 above the individual Polübergänge 24 the corresponding binary digits or bits applied.

The arrangement order of the individual bits in the combined code mark pattern 20 is in Figure 3 shown. There, too, the individual pole transitions 24 are replaced by the respectively corresponding bits of the coding. The coding according to the invention is made up of a per se known binary pseudorandom sequence 25, which is combined with its inverted counterpart 26.

A pseudorandom sequence consists of bit sequences with n binary digits arranged consecutively. Each time you move back by one bit in the binary pseudo-random sequence, then, as is well known, a new n-digit binary bit sequence arises in each case. Such a sequence n consecutive bits is hereinafter referred to as code word. The code words of a binary pseudorandom coding can be generated with the aid of a linear feedback shift register. The number of digits of the shift register corresponds to the number of digits of the binary bit sequence or of the code word. In general, different code words can be distinguished in an m-bit pseudorandom coding n = xexp (m), where x is the valency of the codeword digit and m is the number of digits or bits of the codeword. The largest representable number is N = x exp (m) -1. The larger the number of bits, the more code words can be distinguished from each other.

The in Fig. 3 illustrated embodiment of the invention is based on a pseudorandom sequence 25 of codewords 27 with n = 17 digits. It is 2exp (17) -1 bits long and therefore consists of a total of n = 2exp (17) = 131,072 different codewords 27. According to the invention, the described pseudorandom sequence 25 is in the direction of travel 8 after each bit Valence "0" is a bit of significance "1" and after each "1" bit a "0" bit of the inverse pseudorandom sequence 26 is inserted. Consequently, in the single-lane combined code mark pattern 20, a bit change takes place at the latest after two bits. On the magnetic tape 10, this is shown according to Fig. 3 in that only magnetic poles 22, 23 in the length λ = 4 mm and twice the length of L = 2λ = 8 mm are present, and that at the longest after L = 2λ = 8 mm a transition 24 from a north pole 23 to a south pole 22 or vice versa occurs.

The n1 = 2exp (17) -1 bits of the pseudorandom sequence 25 and the inverse n2 = 2exp (17) -1 bits of the inverted counterpart 26 add up to a total of nK = 2x (2exp (17) -1) bits. In the case of the code mark length λ = 4 mm selected here, this corresponds to a total geometric length of the single-track combined code mark pattern 20 of Lmax = nK * λ = 262144 * 4mm = 1048.576 m.

Viewed analytically, the combination yields a combined code mark pattern 20 in which a total of NK = 2 (2exp (17) -1) -36 = 2exp (18) -2-36 = 262,106 codewords are now distinguished by eighteen digits each. Thus, in addition to doubling the number of bits or magnetic poles 22, 23, the combination according to the invention also yields a code digit gain. With simultaneous sampling of eighteen consecutive of the respective second bits of the combined code mark pattern 20, therefore, a unique 18-digit reading pattern 33 is read out without repetition of code words ( Fig. 2 ).

Accordingly, the code reading sensor 11 according to Fig. 2 for reading the eighteen bit position codes or code words 33, an eighteen position code reader 28 is provided Sensor pairs 29, which are in Fig. 4 geauer is shown. The sensor pairs 29 arranged in the direction of travel 8 on a line with a distance 30 corresponding to the length 2λ = 8mm two magnetic poles 22,23. The two sensors 31,31 'of each of the sensor pairs 29 separates a mutual distance 32 of the size of a half code mark length λ / 2 = 2mm. If one of the two sensors 31,31 'in the vicinity of a magnetic pole change 24 and provides a sensor voltage of approximately zero, then the other sensor 31,31' is certainly in coverage to one of the magnetic poles 22,23 and provides a secure information. All eighteen first sensors 31 are in a first group and all eighteen second sensors 31 'are combined into a second sensor group. Of the sensors 31 of the first sensor group and the offset by half the code mark length λ / 2 = 2mm in the direction of travel sensors 31 'of the second sensor group, only the output signals of the sensors of one of two sensor groups for position reading are alternately selected and evaluated. The reading pattern 33 of the position code reading device 28 Fig. 2 Thus, it is composed of eighteen simultaneously read bits, but only every other bit of the combined code mark pattern 20 is read.

The eighteen bits of a reading pattern 33 simultaneously read by the position code reading device 28 in the manner described are interpreted jointly by the evaluation unit 17 as an eighteen-digit code word. Each of these n = 2 * (2exp (17) -1) -36 = 262'106 eighteen digit code words of the combined code mark pattern 20 is stored in a read-only memory, here an EPROM Translation or decoding table uniquely assigned an absolute position value 35 of the elevator car 2, which is output as a binary number in the correct order. The resolution of the position code reading device 28 here is 4 mm, which corresponds to the length λ of a code mark 21.

Switching to the respective correct one of the two sensor groups of the position code reading device 28 takes place via the determination of the position of the pole transition 24 between a south pole 22 and a north pole 23 with the aid of an interpolation device 36. The interpolation device 36 is either in the direction of travel 8 as in FIG Fig. 2 before or else like here in Fig. 3 behind the position code reading device 28 at a distance 37 of an integer multiple of the length λ = 4mm a code mark 21 arranged. The interpolation device 36 comprises a group of six Hall sensors S0-S5, which are placed one behind the other in the direction of travel 8 at a distance of λ / 2 = 2mm, so that the first Hall sensor S0 and the last Hall sensors S5 accordingly separates a distance of 10mm. In the area between the first Hall sensor S0 and the last Hall sensor S5 is necessarily a zero, ie a pole transition 24 of the above-described combined code mark pattern 20. The interpolation reading 36 detects the present invention created quasi-equidistant pole transitions 24 and zero crossings of the magnetic field between two successive north poles 22nd or South Poland 23.

$$\mathrm{U}\left(\mathrm{s}\mathrm{0}\right)+1/3*\mathrm{U}\left(\mathrm{s}1\right)>0->0$$

$$\mathrm{U}\left(\mathrm{s}\mathrm{0}\right)+\mathrm{U}\left(\mathrm{s}1\right)>0->1$$

$$1/3*\mathrm{U}\left(\mathrm{s}\mathrm{0}\right)+\mathrm{U}\left(\mathrm{s}1\right)>0->1$$

$$\mathrm{U}\left(\mathrm{s}1\right)\mathrm{>}\mathrm{0}->1$$

u.s.w. bis: $$\mathrm{U}\left(\mathrm{s}4\right)+1/3*\mathrm{U}\left(\mathrm{s}5\right)->1$$

In Fig. 5 is an example of the output voltage of the six Hall sensors S0 to S5 of the interpolation device 36 over the path in the direction of travel 8 millimeter intervals shown. Well-known comparator circuits perform the following comparisons of the voltages of individual sensors S0 to S5, which are evaluated as indicated: $$\mathrm{U}\left(\mathrm{s}\mathrm{0}\right)\mathrm{>}\mathrm{0}->0$$

$$\mathrm{U}\left(\mathrm{s}\mathrm{0}\right)+1/3*\mathrm{U}\left(\mathrm{s}1\right)>0->0$$

$$\mathrm{U}\left(\mathrm{s}\mathrm{0}\right)+\mathrm{U}\left(\mathrm{s}1\right)>0->1$$

$$1/3*\mathrm{U}\left(\mathrm{s}\mathrm{0}\right)+\mathrm{U}\left(\mathrm{s}1\right)>0->1$$

$$\mathrm{U}\left(\mathrm{s}1\right)\mathrm{>}\mathrm{0}->1$$

etc to: $$\mathrm{U}\left(\mathrm{s}4\right)+1/3*\mathrm{U}\left(\mathrm{s}5\right)->1$$

This yields for the in Fig. 5 illustrated example, the number sequence: 001111111111111111. Thus, it is expressed that extends to the first interpolation sensor S0 to 0.5 mm behind a south pole 23. From 1.0mm to 9mm behind the first interpolation sensor S0 there is a north pole 22.

The generated number sequence is decoded via a table stored, for example, in an EPROM into a three-digit binary number sequence which contains an interpolation value 46 (FIG. Fig.2 ) with - in the example 3mm represents. This is periodic with the code mark length λ and indicates the polarity of the band from the location of the first Hall sensor S0, calculated stepwise in, for example, 0.5 mm steps. The most significant bit 24 of this interpolation value 46 inverts at a distance of 2 mm and takes over as the scanning signal for the described switching between the sensors 31 and 31 'of the position code reading device 28th The three bits 24 of the interpolation value 46 are additionally included in the overall position information 53. The voltages of the Hall sensors S0-S5 now only have to be compared with the threshold for 0mT, for which purpose a comparator is provided for each of the six Hall sensors S0-S5 of the position code reading device 28. Of the resulting digital bits 24, the correct bits 24 are selected via a number of 2 to 1 multiplexers which are controlled by the 2mm bit 24 of the interpolator 36. All that is needed is a synchronous clock, which can amount to several 100kHz. After one clock cycle (<10ns), the position value is updated.

The single-track measuring system described so far can be constructed with very inexpensive components. It enables high travel speeds of more than 16m / s. The measuring rate is practically only dependent on the speed of the interface. The system resolution of this absolute single-track system is 0.5 mm, but can be significantly increased by the additional use of a Feininterpolationseinrichtung 47.

The fine interpolation unit 47, in addition to the Hall sensors 31, 31 ', S0-S5, samples the combined code mark pattern 20 with an MR sensor 49 (magneto-resistive = inductive resistance sensor). The MR angle sensor 49 is in the embodiment according to Fig. 2 at a fixed distance 1 = kλ, which corresponds to a multiple of the length of a code mark 21 in the direction of travel 8 before and in the embodiment according to Fig. 4 behind the interpolation device 36 at the Code reader 12 is arranged and is moved along with this relative to the magnetic tape 10. In this case, the MR angle sensor 49 detects the course of the magnetic field of the single-track combined code mark pattern 20, which is composed of approximately sinusoidal half-waves of lengths λ = 4mm or 2λ = 8mm, the magnetic fields formed by the north pole 22 and south pole 23.

Fig. 6 shows the course of the output signal 48 of the MR angle sensor 49 used here with the designation LK28 from IMO when scanning the half-waves of the combined code mark pattern 20 along the path in the travel direction 8 plotted. The sinusoidal and cosinusoidal output voltages of the MR sensor 49 are already interpolated in the p-controller by means of an interpolator chip or by software (not shown) and are normalized such that the minimum values 50 are 0 mm and the maximum values 51 are 4 mm. The output signal 48 results in high-resolution position information which is proportional to the path within the length λ = 4 mm of a north pole 22 or south pole 23, or 2λ = 8 mm of two adjacent homopolar magnetic poles.

The course of the output signal 48 of the MR angle sensor 49 can be seen that it is in the range 54 between 0mm and 8mm to a 8mm magnetic pole and 55 in the range between 8mm and 12mm to a 4mm magnetic pole.

This high-resolution position information is processed as follows:

If the MR angle sensor 49 is located above a 4 mm magnetic pole, then the interpolated position information of the fine interpolation device 47 is adopted as a high-resolution position value 52. If the MR sensor 49 is located above an 8 mm pole, then the interpolated position information is multiplied by 2. If the resulting value is greater than the maximum value given here by the length of λ = 4 mm of a magnetic pole, then the maximum value is subtracted.

From this calculation rule results in a code mark length λ periodic position value 52 with a resolution of the order of 50 .mu.m, as previously obtained only from the incremental track of a conventional two-track system.

The information as to whether the MR angle sensor 49 is above a four-pole or above an eight-mm magnetic pole can be stored in the decoding table. The code word 33 is first determined by the position code reading device 28, and both the absolute position 35 and the arrangement of the magnetic poles under the current position of the MR angle sensor 49 are read out via the address of the decoding table indicated by the code word 33.

To calculate the high-resolution overall position 53, the periodic high-resolution position values 52 determined by the fine interpolation device 47 and the absolute position value 35 of the resolution λ = 4 mm determined by the position code reading device 28 are synchronized with one another in a p-controller 40. This is easily possible because the absolute position 35 as before described with a resolution of 0.5mm is available.

The calculation of the high-resolution total position 53 of the elevator car 2 consisting of a total of twenty-four bits 24 can be carried out very quickly since only a few simple operations, such as e.g. Comparisons, bit shifts, additions and subtractions are necessary.

The possible by the inventive coding and the position code reading device 28 high traversing speed is not affected by the Feininterpolationseinrichtung 47 when a Interpolatorchip used with parallel output of the interpolated position information and the high-resolution position value 52 synchronously caches at the same time with the absolute position value 35 by the synchronous clock.

In the Fig. 6 recognizable distortions in the course 48 of the interpolated position value obtained by fine interpolation can be equalized by an equalization table for four and eight millimetric magnetic poles, respectively, which considerably improves the accuracy. This is possible because the distortions of magnetic poles of equal length λ or 2λ are very similar at all points of the combined code mark pattern 20.

In Fig. 7 an embodiment of the invention is shown in which the code reading sensor 11 is redundant. The second code reading sensor 11 'has basically the same structure as the code reading sensor 11 in the first exemplary embodiment described above Fig. 4 , In difference For the first embodiment of the code reading sensor 11, in the second code reading sensor 11 ', the interpolation device 36' and the fine interpolation device 47 'are arranged in this direction in the direction of travel 8 in front of the position code reading device 28.

The second code reading sensor 11 'is placed mirror-symmetrically to the first code reading sensor 11, wherein the sensor pairs 29, 29' of both position code reading devices 28, 28 'mesh in a line parallel to the travel / reading direction 8 by a code mark length λ = 4 mm. In this position, the eighteen sensor pairs 29 'of the second position code reading device 28 detect a reading pattern 33 of eighteen of the respective first bits of the combined code mark pattern 20.

As Fig. 8 1, each of the two code reading sensors 11, 11 'is assigned its own evaluation unit 17, 17', so that the output signals of the sensors of both code reading sensors 11, 11 'are evaluated independently of one another and two independently determined high-resolution values of the overall position 53, 53 as a binary number are available with twenty-four locations to control the elevator.

On the basis of the redundancy provided by the absolute measuring system according to the invention for determining the absolute cabin position, a comprehensive shaft information system with numerous functions can thus be obtained in cooperation with additional elevator sensors.

Examples of such functions of a shaft information system which are based on the determination of the absolute cabin position are: the end-of-travel delay, end-of-shaft limitation, floor detection, level compensation, door bridging, as well as a wide variety of cruise controls, etc.

Fig. 7 a redundant design of the single-track measuring system as the basis of a shaft information system.

The redundant design of the single-track measuring system is, together with one floor sensor 41, 41 'in each case, the basis of a comprehensive shaft information system, which is shown schematically in FIG Fig. 7 is shown. Each evaluation unit 17, 17 'is assigned to one of the floor sensors 41, 41'. The floor sensors 41, 41 'are moved together with the elevator car 2 in the shaft 1 in order to detect position markings 42, 42' arranged in the shaft 1 at each floor level. These signals of the floor sensors 41,41 'are processed together with the output signals of also redundantly provided safety devices 43,43' together with the position information 53 and serve to control the elevator.

The Längencodemarkenmuster 20 of the magnetic tape 10 is shown in this embodiment by different pole magnetized sections and is read by magnetic field-sensitive sensors 31,31 ', S0-S6 of the code reader 12. In principle, other physical principles for representing the length coding are also conceivable. Thus, the code marks can also have different dielectric constants, which are read by sensors detecting capacitive effects. Furthermore, a reflective code mark pattern is possible, in which, depending on the value of the individual code mark, more or less light is reflected by an illumination device to reflex light barriers than sensors.

The invention enables the use of inexpensive Hall sensors for reading the Postionscodes. Basically, an implementation but also with costly induction generator, so-called GMR sensors or magnetic field detecting magnetoresitive sensors, so-called MR sensors possible. Of each of these sensors, either a plurality of individual and / or a group of different sensors can be combined with one another on a code reading device.

Claims (13)

1. Lift installation with a length measuring system for determining a cage position of a lift cage (2) movable along at least one guide rail (7), with a code mark pattern (20) mounted near the lift cage parallel to the travel direction (8), with a code reading device (12), which is mounted on the lift cage, for contactless scanning of the code mark pattern, and with an evaluating unit (17) for evaluating scanned code mark patterns, wherein n successive code marks (21) of the code mark pattern form a code word (27), code words are uniquely arranged in an n-digit pseudo random sequence of different code words, the code words form a single-track code mark pattern and a scanned code word represents an absolute cage position (35), characterised in that the code mark pattern is coded in Manchester coding so that a code mark change takes place at the latest after each second code mark and that the code reading device (12) comprises at least two sensors (31, 31') which are arranged to be offset in travel direction by half the code mark length so that a first sensor (31) on detection of a code mark change (24) generates a scanning signal by which a second sensor (31') is activatable for detecting the code word.
2. Lift installation according to claim 1, characterised in that by means of the scanning signal the output signal of one of the two sensors (31, 31') is selected and evaluated in alternation.
3. Lift installation according to claim 1 or 2, characterised in that the code marks form magnetic poles and that the code reading device comprises Hall sensors (31, 31', S0 - S5).
4. Lift installation according to any one of claims 1 or 3, characterised in that the code reading device comprises a plurality of sensors for simultaneous scanning of the code marks of a code word.
5. Lift installation according to any one of claims 1 to 4, characterised in that the code reading device comprises a plurality of sensors (SO - S5) for detecting code mark transitions, which sensors are arranged in travel direction over a region with a length greater than the length (2λ) of two code marks at a spacing smaller than the length of one code mark (λ).
6. Lift installation according to any one of claims 1 to 5, characterised in that the code reading device detects at least one transition (24) between code marks.
7. Lift installation according to any one of claims 4 to 6, characterised in that a comparator compares a voltage of the sensors with a threshold.
8. Lift installation according to claim 6, characterised in that the resolution of the absolute cage position through scanning of a code word corresponds with the length of a code mark and/or that the resolution of the absolute cage position through detection of a transition (24) between code marks is 0.5 mm.
9. Lift installation according to any one of claims 1 to 8, characterised in that at least one storey sensor (41, 41') is mounted at the lift cage, which storey sensor detects position markings (42, 42') mounted on the storey level and that a control evaluates detected position markings by scanned code words.
10. Lift installation according to any one of claims 1 to 9, characterised in that the code reading device is of redundant construction.
11. Lift installation according to any one of claims 1 to 10, characterised in that the code mark pattern is mounted on the guide rail (7) and/or that the sensors are arranged in a line parallel to the travel direction.
12. Lift installation according to claim 3, characterised in that the code reading device comprises a fine interpolation unit (47) detecting the course of the magnetic field of the code mark pattern, which carries out arctan interpolation of the course of the magnetic field of the code mark pattern and which produces a high-resolution value which is periodic with the code mark length.
13. Lift installation according to claim 1, characterised in that the code marks have different dielectric constants and that the code reading device comprises sensors detecting capacitive effects.

Images