Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
  • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
  • G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
  • G01D5/244—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing characteristics of pulses or pulse trains; generating pulses or pulse trains
  • G01D5/249—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing characteristics of pulses or pulse trains; generating pulses or pulse trains using pulse code
  • G01D5/2492—Pulse stream
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
  • H03M1/00—Analogue/digital conversion; Digital/analogue conversion
  • H03M1/06—Continuously compensating for, or preventing, undesired influence of physical parameters
  • H03M1/0617—Continuously compensating for, or preventing, undesired influence of physical parameters characterised by the use of methods or means not specific to a particular type of detrimental influence
  • H03M1/0675—Continuously compensating for, or preventing, undesired influence of physical parameters characterised by the use of methods or means not specific to a particular type of detrimental influence using redundancy
  • H03M1/0678—Continuously compensating for, or preventing, undesired influence of physical parameters characterised by the use of methods or means not specific to a particular type of detrimental influence using redundancy using additional components or elements, e.g. dummy components
  • H03M1/068—Continuously compensating for, or preventing, undesired influence of physical parameters characterised by the use of methods or means not specific to a particular type of detrimental influence using redundancy using additional components or elements, e.g. dummy components the original and additional components or elements being complementary to each other, e.g. CMOS
  • H03M1/0685—Continuously compensating for, or preventing, undesired influence of physical parameters characterised by the use of methods or means not specific to a particular type of detrimental influence using redundancy using additional components or elements, e.g. dummy components the original and additional components or elements being complementary to each other, e.g. CMOS using real and complementary patterns
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
  • H03M1/00—Analogue/digital conversion; Digital/analogue conversion
  • H03M1/12—Analogue/digital converters
  • H03M1/22—Analogue/digital converters pattern-reading type
  • H03M1/24—Analogue/digital converters pattern-reading type using relatively movable reader and disc or strip
  • H03M1/28—Analogue/digital converters pattern-reading type using relatively movable reader and disc or strip with non-weighted coding
  • H03M1/282—Analogue/digital converters pattern-reading type using relatively movable reader and disc or strip with non-weighted coding of the pattern-shifting type, e.g. pseudo-random chain code

Definitions

• the invention relates to a position measuring device with a measuring standard and a scanning device for scanning the measuring standard.
• Position measuring devices with a single-track absolute code also called chain code or pseudo-random code
• the measuring standard consists of a code track with code elements of the same width arranged one behind the other in the measuring direction.
• the code elements are provided in a pseudo-random distribution, so that a certain number of successive code elements each form a code word and all code elements form a continuous sequence of different code words.
• a new code word that uniquely defines an absolute position is already pending after a displacement path corresponding to the width of a code element.
• Such a position measuring device is described in detail in DE 39 42 625, for example.
• the disadvantage here is that in the case of a relatively long material measure, that is to say in the case of a large measuring range, there are relatively long areas with similar properties.
• the position measuring device is a magnetic measuring device, for example, then the code elements consist of north and south poles.
• An area with many code elements of the same magnetization generates a constant field which complicates the evaluation and which undesirably influences an adjacent measuring standard, in particular an incremental division.
• the position measuring device according to JP 3- 296620 has the same disadvantage, in which the inverse code word is applied in the measuring direction after each code word.
• the position measuring device according to the invention has the advantage that only a few adjacent code elements have the same properties.
• FIG. 1 shows a position measuring device according to the invention with a single-track magnetic measuring standard.
• the invention is explained with reference to FIG. 1 and Tables 1 and 2 using an example in which a material measure 1 with magnetic code elements 10, 100 is scanned by a scanning device 2.
• the code elements 10, 100 are magnetic poles of different magnetization, which is represented schematically by the direction of the arrows.
• the absolute position 4 is uniquely determined using a single-track code with a width of the code words of five code elements.
• a customary serial code is defined by a sequence of code elements 10 (physical sequence) according to Table 1. This code is also called chain code or pseudo-random code.
• a code element 10 labeled "0" is, for example, a south pole and a code element labeled "1" is a north pole, ie the north pole has an inverted property with respect to the south pole.
• code word width of five code elements 10 32 different code words can be formed, which in turn can code 32 different absolute positions 4. It can be seen from Table 1 that the sequence of the code elements 10 is selected such that when the scanning unit 2 is shifted by the width B of a code element 10, a single there is a clear code word that differs from the other code words.
• the sequence of code elements 10 in Table 1 has multiple successive code elements 10 with the same properties, in the example the same magnetization.
• the first five code elements 10 are each identical.
• This relatively large homogeneous area extended in the measuring direction X generates a large DC field which can lead to undesirable influences, in particular an incremental neighboring track, or which makes an optimized design of the scanning device 2 difficult.
• the code element 100 inverted for this purpose is inserted into the sequence of code elements 10 after each code element 10, as shown in Table 2 for the same section of the code sequence as in Table 1.
• Inverted code elements 100 are shown in italics.
• the order of the original and inverted code element 10, 100 can also be interchanged, so that first the inverted and then the original code element 10, 100 is arranged in the code sequence.
• the original code elements 10 and the inverted code elements 100 which are each in the same place in the code word, are alternately arranged in succession.
• the resulting sequence of code elements 10, 100 is shown in Table 2.
• the scanning device 2 contains five detector elements 2.1, 2.2, 2.3, 2.4, 2.5, which are each arranged at a mutual distance T from two code elements 10, 100. This ensures that a code word is derived either only from original code elements 10 or only from inverted code elements 100, since all detector elements 2.1 to 2.5 face either the original or the inverted code elements 10, 100.
• the scanning signals of the detector elements 2.1 to 2.5 are used to address a memory 3.
• the scanning signals 5 are transcoded into absolute positions 4 in the memory 3.
• the scanning device 2 moves by one code element 10, 100, that is, by B further the "1st Inverted code word "(11111) decoded as second absolute position 4, scanner 2 moves further by a further code element, if second code word (00001) is decoded as third absolute position 4, scanner 2 moves further by another code element, this becomes "2nd code word inverted” (1 1110) decoded as fourth absolute position 4.
• the sequence of the code shown in Table 2 consists of two rows of code words, a row of code words forming a one-step code which, however, only comprises half the number space corresponding to the bit length (for 5 bits: 16 code words). These code words are different and none of the code words is inverse to any of the other code words.
• the second row of code words is generated by inverting the code elements of the code words of the first row and forms the further half of the number range corresponding to the bit length.
• the sequence of the overall code is carried out by nesting in such a way that an inverted code word is inserted into an associated code word, this insertion can also be referred to as interleaving, so that the code word and its inverted code word overlap in the sequence.
• the frequency of the arrangement of similar code elements 10, 100 can also be reduced if the inverted code elements 100 are not inserted directly onto the unchanged code element 10, but only after one or more code elements 10. It is assumed that a code word from M If there are> 1 code elements, N code elements N further code words can be inserted between two code elements 10 of a first code word, with 0 ⁇ N ⁇ M. In order to change the properties of the code elements 10, 100 subsequently, the code elements 100 one of the inserted code words is made inverse to the code elements 10 of the first code word.
• the mutual distance T between the detector elements of the scanning device 2 is (N + 1) times the width B of a code element 10, 100.
• the invention can be used in length and angle measuring devices. When used in angle measuring devices, the use of closed rows of code words is advantageous.
• the end of a series of code words can be connected seamlessly to the beginning.
• a clear absolute position can also be detected at every position in the transition area between the start and end.
• the code elements can be arranged symmetrically on a disk or on the circumference of a drum with respect to an axis of rotation.
• the invention can be used particularly advantageously for M greater than or equal to 7 and N equal to 1.
• the advantages of the invention are particularly evident in the case of a magnetic material measure in which the code elements 10, 100 consist of magnetic poles of the same width B.
• the magnetic poles can be implemented on the basis of plastic-bonded magnets or metallic or ceramic hard magnets.
• the detector elements 2.1 to 2.5 are advantageously Hall elements, but magnetoresistive sensors or sensors with high magnetic resistance can also be used.
• the invention can also be used advantageously in optical, capacitive or inductive position measuring devices.
• the code elements consist of transparent or reflective areas and inverse non-transparent or non-reflective areas of the same width B.
• the property defined as inverse above can also be referred to as complementary, wherein depending on the physical scanning principle, the code element 10 and the inverse code element 100 have complementary physical properties - in the example opposite direction of the magnetization.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Theoretical Computer Science (AREA)
• Transmission And Conversion Of Sensor Element Output (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

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Cited By (2)

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Citations (1)

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• 1999
  • 1999-08-03 DE DE19936582A patent/DE19936582A1/de not_active Withdrawn
• 2000
  • 2000-08-03 US US10/048,828 patent/US6760682B1/en not_active Expired - Fee Related
  • 2000-08-03 WO PCT/EP2000/007511 patent/WO2001009568A1/de not_active Ceased
  • 2000-08-03 EP EP00948021A patent/EP1206684B1/de not_active Expired - Lifetime
  • 2000-08-03 JP JP2001513801A patent/JP4468619B2/ja not_active Expired - Fee Related
  • 2000-08-03 DE DE50008526T patent/DE50008526D1/de not_active Expired - Lifetime

Patent Citations (1)

Non-Patent Citations (2)

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