DE3409544C2 - - Google Patents

Description

The invention relates to an incremental length or angle measuring device according to the preamble of claim 1.

In the main patent 33 11 204 is an incremental length or angle measurement direction for measuring the relative position of two objects te described, in which a material measure in Form of a first index plate on a shaft is consolidated, which is rotatably mounted in a housing is; the shaft and the housing are with the too measuring objects connected. The first part be shows a first incremental division with abso lut assigned reference marks, which again to one code mark for identification is ordered. On the shaft is a second part disc with a second increment, with a marker at the start of the meter, with a Mar to stop the counter and with a scanning field for scanning the code marks of the first part be rotatable gela relative to the first disc device. A scanner is fixed in the housing  tion attached with a scanning plate, each a scan field for scanning the first incremental division of the first segment and the second Incremental division and the marking for toughness has the second partial disc. To Ge Finding a reference position at the start of a measurement or to reproduce this reference position at egg ner fault in which the current position measurement If the value is lost, the measuring objects and thus also the first part slice a counter in the evaluation device of the Measuring device, for example, set to zero and the second indexing disc by means of a motor in Rotation offset. If the scan field of the scan put the mark for the counter start on the two the dial is scanned, the counter is started. From that point on, the second incremental division of the second indexing disk from the associated one Scanning field on the scanning plate and the Division periods of this second incremental division counted when the second indexing disc rotates. If the marker to stop the meter on the second part disc the next reference mark on the quietest The first partial disc is scanned, the counter stopped. The counter now contains a position measurement worth the angular path that the second indexing disk from Has started the counter until it stops. The scanning field on the second graduated disc for the Ab buttons of the code marks on the first graduated disc at the same time the absolute position value from the scanned reference mark associated code mark read. This absolute position value is now in the  Evaluation device entered and the position added measured value of the counter. In the evaluation direction is the absolute position value, the first part of the disc to the housing at the moment takes. After obtaining the reference position the measurement started or after this reproduction tion of the reference position resulting from the disturbance interrupted measurement can be continued by pressing the first incremental division of the three again The first partial disc from the associated scanning field on the scanning plate of the scanner groped and the division periods of these first Incremental division can be counted; at the meter gear is the position measurement of the moment tanen position of the first disc with respect to the Housing available.

The scanning plate of the scanner of this measuring facility has two division levels, the stu are staggered parallel to each other. On the The scanning field is located on the first division level for the first incremental division the first part disc and on the second division level the Ab touchpad for the second incremental division of the second disc and the scanning field for the Mar Marking to start the counter on the second part be. Such a scanning plate with scanning fields in two graduation staggered to each other levels are relatively complex to manufacture. In addition, the first is on the first indexing disc Incremental division on one surface as Division level and the reference marks with the assigned appropriate code marks on the opposite upper area as division level. The setting of the op the minimum distances (scanning column) between the under  mutually corresponding division planes of the samples plate, the first disc and the second part disc is therefore also expensive.

The invention is based, in one incremental measuring device of the type mentioned, at the after loss of location information in unknown mo ment positions without moving the objects to be measured a reference position is to be reproduced, the Her position of the scanning plate and the measuring standard simplify and setting the optimal distances between the corresponding division to facilitate levels.

This object is inventively characterized by nende feature of claim 1 solved.

The advantages achieved with the invention are in particular special in that the scanning plate instead of two graduation levels for the scanning fields only has one division level and that the first incremental graduation of the material measure together with the absolutely assigned reference mar and associated code marks on only one surface the measuring standard is located as a division level. The Production of the scanning plate and the measuring standard are thus considerably simplified and cheaper and the Setting the optimal distances between each other the corresponding division levels much easier tert, so that overall a simpler and less expensive measuring device with reduced adjustment effort results.

Advantageous embodiments of the invention can be found in the Subclaims.

An embodiment of the invention is based on the Drawing explained in more detail.  It shows

Figure 1 is an incremental Winkelmeßein direction in longitudinal section.

Fig. 2 is a view of a section of a second partial plate;

Fig. 3 is a view of a section of a first disc and

Fig. 4 is a view of a scanning plate.

The incremental angle measuring device shown in longitudinal section in FIG. 1 has a housing 1 which is fastened in a manner not shown to a first object to be measured in the form of the bed of a processing machine. A shaft 2 protrudes from the housing 1 and is attached to a second object to be measured in the form of a spindle of the processing machine. The shaft 2 is in the Ge housing 1 and rotatably supported in the interior of the housing 1 with a material measure in the form of a He most disk 3 connected. This first part be 3 is shown in detail in Fig. 3 and has on a first division level TE ₁ a first incremental graduation 4 in the form of a grating and the first incremental graduation 4 absolutely assigned reference marks R ₀ . . . R _n on. The absolute position of the individual reference marks R ₀ . . . R _{n with} respect to the division zero 0 of the first incremental division 4 becomes C ₀ by code marks. . . C _n indicates the absolute positions of the associated reference marks R ₀ . . . R _n contain as coded information, for example as a so-called barcode. The reference marks R ₀ . . . R _n consist, in a manner not shown, of identical line groups with a certain irregular line distribution.

On the shaft 2 , a carrier body in the form of a second partial disk 5 relative to the first partial disk 3 is rotatably mounted. A second graduation plane TE ₂ on the second graduation disk 5 faces the first graduation plane TE ₁ on the first graduation disk 3 at a certain parallel distance and, according to a section according to FIG. 2, has a second incremental graduation T ₂ as a scanning field for the first incremental graduation 4 of the first partial disk 3 ; the second incremental division T ₂ is identical to the first incremental division 4 . On the second graduation plane TE _{2 of} the second graduated disk 5 there are also scanning fields 17 for the reference marks R ₀ . . . R _n and scan fields 18 for the associated code marks C ₀ . . . C _{n is provided} on the first partial disk 3 ; these scanning fields 17 have a with the Strichver distribution of the reference marks R ₀ . . . R _n identical stroke distribution. Furthermore, there is a third incremental graduation 6 on the second graduation level TE ₂ , which corresponds to the first incremental graduation 4 of the first graduated disk 3 with respect to the angular increments, ie the scanning of the third incremental graduation 6 and the scanning of the first incremental graduation 4 each result in the same position value for a certain identical angle position of the second partial disk 5 and the first partial disk 3 . On the second graduation level TE ₂ of the second graduation disc 5 there are still markings 15 for starting a counter, each consisting of identical stroke groups with a certain irregular stroke distribution.

In the housing 1 , a scanning device 7 with a lighting 11 , a condenser 12 and a photosensor 13 is arranged on a plate 14 . The scanning device 7 also contains a scanning plate A , which has ₃ scanning fields 10 for the third incremental graduation 6 and a scanning field 16 for the markings 15 of the second graduated disk 5 according to FIG. 4 on a third graduation plane TE ; the scanning field 16 has the same line distribution as the markings 15 and the divisions of the scanning fields 10 coincide with the third incremental division 6 . In each case one photosensor 13 is assigned to the following pairings: marking 15 - scanning field 16 , third incremental division 6 - scanning fields 10 , first incremental division 4 - second incremental division T ₂ , reference marks R ₀ . . . R _n - From scanning fields 17 , code marks C ₀ . . . C _n scan fields 18 .

In the actual measuring process, the first incremental graduation 4 is rotated relative to the second incremental graduation T ₂ as the scanning field when the shaft 2 and thus the first graduated disk 3 with the second graduated disk 5 stationary. The luminous flux emanating from the loading 11 is modulated by the relatively moving first and second incremental divisions 4 , T ₂ and falls on the associated photosensor 13 , which provides a periodic analog signal, which is in an evaluation device (not shown) of the measuring device in pulse is reshaped. These pulses are counted in a counter of the evaluation device and can be displayed in a downstream display unit as position measurement values in digital form or can be fed directly to a numerical control device of the processing machine.

With an incremental measuring device it is of great importance at the beginning of a measurement to determine a reference position as the starting point position for the measurements and also after Incidents can be reproduced again.

It is assumed that before the start of a measurement or in the event of a fault, in which - for example due to a power failure - the position measurement value is lost in incremental measuring devices, which are movable relative to each other, objects to be measured are at a standstill. The first graduated disk 3 is therefore in a position in which the position of its zero point of division relative to the housing 1 and thus also to the sampling plate A is not known.

To obtain this reference position, the current position of the first indexing disk 3 must now be determined bezüg Lich of the housing 1 . For this purpose, in a known and therefore unspecified manner, a counter in the evaluation device is set to the value zero or to another numerical value and, at the same time, the calibration mode is switched on by the second partial disk 5 from a motor M fastened in the housing 1 Toothed belt gear G is rotated. If one of the markings 15 for the counter start on the second graduated disk 5 is scanned by the scanning field 16 on the stationary scanning plate A , the associated photosensor 13 supplies a signal which, in the calibration mode, controls the counter (not shown) in the evaluation device and starts it . From this point in time, the periodic analog signal generated by the associated photo sensor 13 during the scanning of the third incremental division 6 of the second graduated disc 5 by the scanning fields 10 from the scanning plate A and the division periods of the third incremental division 6 counted by the counter.

After the counter has started, the next reference mark R _i ( i = 0.1,..., N) is scanned by the reference mark scanning field 17 and the counter is stopped by a signal from the associated photosensor 13 . Simultaneously, the code marks scanning field 18 and the corresponding photo sensor 13 has from which the reference mark R _i associated code mark C _i the absolute Po sitionswert the reference mark R _i read, which has stopped the counter. This absolute position value of the reference mark R _i is now fed into the evaluation device and superimposed on the counter value taken from the third incremental division 6 in the counter. In the evaluation device is now the absolute position value that the first part be 3 to the housing 1 currently occupies. The second indexing disk 5 is stopped and the calibration process is ended. The counter can now be fed again during the actual measuring process with the counter pulses which, when the first part 3 rotates, when the first incremental division 4 is scanned by means of the second incremental division T _{2 of} the stationary second part plate 5 with respect to the housing 1 and by means of of the associated photosensor 13 are generated.

If malfunctions occur, for example in the event of a power failure, the reference position for the first indexing disk 3 can be reproduced analogously by means of the calibration process described above, even if the first indexing disk 3 cannot be moved out of its current position because, for example, a tool is currently being used the spindle of the Bear processing machine is in operative connection with the shaft 2 , is engaged in a workpiece to be machined when the fault occurs.

As described above, at coincidence of the marking 15 on the second rotating part disk 5 with the scanning field 16 on the scanning plate A, the counter is started and the division periods of the third incremental division 6 on the second dividing plate 5 by means of the scanning fields 10 on the scanning plate A is counted until the counter is stopped at the coincidence of the scanning field 17 on the second graduated disk 5 with the next reference mark R _i on the first graduated disk 3 following the start of the counter, with the scanning field 18 on the second graduated disk 5 simultaneously The associated code mark C _{i is} scanned on the first graduated disk 3 and this absolute position value of the reference mark R _{i is} superimposed in the evaluation device on the count value determined from the third incremental division 6 . This again defines the absolute position value, which represents the current position of the zero point of division 0 of the first indexing disk 3 with respect to the housing 1 . In the description of the calibration process and the reproduction process, it was assumed that the shaft 2 with the first disc 3 is stationary with respect to the housing 1 ; however, this is not a requirement. Provided, however, must be that the second code wheel 5 rotates in the calibration process or in a reproduction operation faster than the first part of disc. 3 The reference value is taken over at the moment when the scanning field 17 on the second partial disk 5 scans the reference mark R _i on the first partial disk 3 .

Even during the actual measurement process is a stand still the second disc 5 with respect to the Ge housing 1 is not a condition. But since the first incremental division 4 of the first rotating part 3 be scanned by the second incremental T _{2 of} the two th part 5 , which just rotates relative to the housing 1 , this rela tive rotation of the second part 5 with respect to the housing 1st can be compensated for by counting the division periods of the third incremental division 6 when scanning through the scanning fields 10 on the scanning plate A ; these count values are superimposed in the evaluation device on the position measurement values determined from the first incremental division 4, depending on the direction of rotation of the second indexing disk 5, by addition or subtraction; for this purpose, the counter is designed as a differential counter. The direction of rotation of the second indexing disk 5 is discriminated by two scanning fields 10 offset from one another by a quarter of the division period of the third incremental graduation 6 on the scanning plate A.

As can be seen from Fig. 1, the scanning plate A is arranged on the periphery of the first disc 3 , so that the first parting plane TE ₁ of the first part disc 3 with the third parting plane TE _{3 of} the scanning plate A is aligned in a radial plane to the shaft 2 lies. The first parting plane TE ₁ and the third parting plane TE ₃ lie opposite the second parting plane TE _{2 of} the second part plate 5 at a parallel distance. The setting of an optimal distance for the scanning between the three division levels TE ₁ , TE ₂ , TE ₃ is therefore particularly easy to carry out.

To discriminate the direction of rotation of the first indexing disk 3 , either the first incremental division 4 or the second incremental division T _{2 can} consist of two concentric divisions, offset by a quarter of the division period, extending over 360 °.

Claims (3)

1. incremental length or angle measuring device with a material measure, the markings in the form of an incremental graduation and at least one absolutely fixed to the division zero point has the reference mark, with a scanning device which carries scanning fields for scanning markings and is connected to an evaluation device, and with a carrier body with scannable markings, which is relatively movable both for the material measure and for the scanning device and whose markings can be brought into coincidence with the markings of the measuring standard and / or the scanning fields of the scanning device, with the respective markings being coincident and scanning fields control processes - preferably counter start, incremental count and counter stop - can be triggered in the evaluation device according to patent 33 11 204, characterized in that the scanning field (T ₂ ) for scanning the first incremental division ( 4 ) of the material measure ( 3 ) is arranged on the carrier body ( 5 ). 2. Incremental angle measuring device according to claim 1, characterized in that the carrier body ( 5 ) is rotatably mounted in the form of a second partial disk concentrically to the material measure ( 3 ) in the form of a first partial disk and that the carrier body ( 5 ) the scanning field (T ₂ ) in the form of a second incremental graduation for scanning the first incremental graduation ( 4 ) of the material measure ( 3 ) and a third incremental graduation ( 6 ), at least one marking ( 15 ) for starting the counter, at least one reference mark scanning field ( 17 ) for stopping the counter and at least one Has code mark field ( 18 ). 3. Incremental angle measuring device according to claim 2, characterized in that the first incremental division ( 4 ) or the second incremental division (T ₂ ) consists of two concentric to each other, offset by a quarter of the division period.