DE8307145U1 - Measuring device - Google Patents

Description

- 1 -
WL, JOHANNES HEIDENHAIN GMBH February 21, 1983

Measuring device

The invention relates to a measuring device according $ em preamble of claim 1.

With such a measuring device, the electrical control ' impulses can be used in different ways'. e.g. to reproduce the zero position in the counter, for moving to a certain position at the beginning of the measurement and for checking interference pulses as well as to act on a downstream control device.

An incremental length or angle measuring device is known from DE-PS Zh \ 6 212, in which, in addition to the incremental graduation, reference marks are provided on a separate track. The absolute values of these reference marks are determined from the different distances between the individual reference marks; these distances between the reference marks are determined by scanning the incremental graduation. To recognize the

absolute position of a reference mark therefore always two reference marks are scanned »This procedure is cumbersome and time-consuming if, for example, two such reference marks are far apart. In addition, with a incorrect counting of the increments between two reference marks incorrect distances and thus incorrect Absolute values for the reference marks can be determined.

In DE-PS 29 52 106 is an incremental length or Angle measuring device described »with reference marks on a scale in addition to the graduation different line group distributions are provided. The individual reference marks are scanned by scanning fields in a scanning unit, each scanning field being unique to a reference mark is assigned by using the same dash fonts having. This arrangement is'.

relatively complex, since the line group distributions of the individual reference marks are as strong as possible must differ from each other in order to clearly identify the individual reference marks to enable. The scanning unit must have an identical scanning field for each reference mark.

DE-OS 30 39 ^ 83 shows an incremental one Length or angle measuring device, in addition to A reference mark track and a code mark track are arranged parallel to one another in a division track are. For scanning the reference marks and the respective Associated code marks, however, require separate scanning fields in a scanning unit ^

Each code mark is assigned its own scanning field.

The invention is based on the object, in such a measuring device, the scanning of the Reference marks and the associated code marks to simplify significantly.

This object is achieved according to the invention by the characterizing Features of claim 1 solved.

The advantages achieved by the invention are in particular that the number of scanning fields can be significantly reduced by the proposed arrangement of the code marks, since the Scanning field for the code marks is integrated in the scanning field for the reference marks; this common Only one scanning element is assigned to the scanning field. This arrangement of the code marks results when scanning the reference marks only a DC voltage component in the generated scanning signal, so that a reliable detection of the reference marks and a clear reading of the code information: nnation the code marks is guaranteed

Advantageous further developments of the invention can be found in the subclaims.

Embodiments of the invention are explained in more detail with reference to the drawing.

Show it

Figure 1 schematically an incremental

Length measuring device, Figure 2 shows a scale and a scanning

plate of the length measuring device,

Aft. ti "

ι Figure 3 is a signal diagram of reference

and code signals and

ι ^λ figure k a section of the scale

and the scanning plate

Figure 2.

Xn Figure 1 is schematically a photoelectric

,; incremental length measuring device shown, the

\ 10 from a scale M and from a scanning unit A.

'. exists, each in a manner not shown

are connected to objects to be measured on a processing machine. On the M scale there is an incremental one Graduation T in the form of a line grating (Figure 2) applied, which is photoelectrically in incident light is scanned by the scanning unit A without contact. Along the division T is on the

Scale M a series of reference marks R

(η = 1, 2, 3 »···), each of which is identical,

table groups of lines with a specific line

exhibit distribution. _{The periodic scanning signals S 1} generated by scanning the graduation T,

Sp, which are amplified in the scanning unit A and converted into square-wave signals S ₁ ¹ , S ₂ ¹ , control an electronic counter Z, which displays the measured values in digital form. _{The square-wave signals S 1} ', S ₂ ^{1 which} are phase-shifted from one another by a quarter of the grating constant (graduation period) of the graduation T serve to discriminate the scanning direction. The reference signal RS generated at the reference marks K is amplified in the scanning unit A, converted into a square-wave signal RS 'and also fed to the counter Z.

With the reference signals RS obtained, various Functions are triggered. By evaluating the reference signals RS, an incremental unit becomes Measuring device a quasi-absolute measuring device if each reference mark R is a number which represents their absolute position in relation to an unchangeable zero point. Furthermore, a certain reference mark R

serve to counter Z when the reference value obtained from the specific reference mark R occurs

signals RS to the "value" zero ". However, these functions can only be carried out if the selected Refi
can be.

selected reference mark R clearly identified

For identification, at least one code mark C (n, m = 1, 2, 3 * ··) is serially assigned to each of the identical reference marks R; the code marks C follow one another without gaps in the measuring direction X and are arranged according to FIG. From the series of reference marks R, only one reference mark R is represented - ^ η η

which is assigned the code marks C - C " are. The reference mark R consists of a line

group with three lines running transversely to the measuring direction X with a certain line distribution, the is identical for all reference marks R.

For scanning the scale M is in the scanning unit A a scanning plate AP according to Figure 2 is provided for scanning the division T two by one Quarter of the lattice constant of the pitch T

»I ·« · k I · Uli * I ····

»■» · B l «(l *

«I k · ·» «till I

the other has offset _{scanning fields AT 1} , ATp which are identical to the pitch T; Photo elements (not shown) for generating the scanning signals S-, S "are assigned to the scanning _{fields AT 1 J AT".} For scanning the reference mark R, a scanning field AR is provided on the scanning plate AP, to which a photo element (not shown) for generating the reference signal RS is assigned. To scan the lower row of code marks C .., C ₂ , Cr, a scanning field AC is provided on the scanning plate AP, which is integrated in the scanning field AR} the said photo element also serves to generate the code signals CS-CS_. No scanning field is assigned to the upper row of code marks C ″, C * The scanning field AR corresponds to the reference mark R and the scanning field AC corresponds to the codes

brands C match,
no

_{The code signals CS 1} - CS generated by the scanning field AC when the scale M is scanned in the positive measuring direction X from left to right result in the binary combination "11010" for unambiguous identification

verification of the associated reference mark R "

(Figure 3) · The code marks C, - C _ are also derived from ^λ ni n5

the scanning field AR for the reference mark R is scanned.

Since the code marks C _Λ - C _ according to their code

ni n5

information are offset parallel to one another without creating a gap in the measuring direction X, and since the Total width a of the parallel offset code marks C "- C _ only part of the width b of the reference ni n5

mark R is perpendicular to the measuring direction X, when the code marks C ₁ -Cj are scanned, the scanning field AR in the associated photo element only

a DC voltage signal is generated which is the exact

Determination of the reference signal RS not affected

pregnant. The code signals CS _Λ - CS _ are the

ni n5

Evaluation device in the counter Z supplied.

If the scanning unit A scans the scale M in the positive measuring direction X from left to right, then so

the next code follows the reference mark R.

brands C-. and then the associated reference _{mark R n + 1} etc. (not shown in FIG. 2). In order to be able to recognize the first code mark C- _{1 in this scanning direction, this code mark C n + 1 1 should} have the binary value "1", for example.

In general, the code marks C can start

»Mn

15 and end information. With the initial information, the evaluation device in the meter Z be prepared for reading out code information following the initial information will. The end information serves to ensure that the entire code information has been read out;

as a result, a possible reversal of the measuring direction X in the middle of the scanning of the code information be recognized.

When moving the scanning unit A in positive

Measuring direction X from left to right, the code information of the code marks C is scanned before

nm

the scanning of the associated reference mark R. When scanning in the negative measuring direction -X from right to left, the direction-dependent Evaluation of the code information recognized,

that after the code marks C _1, the reference mark R

η + ι, m η

must follow.

- 8th -

f The code marks C and the reference

if nni

J: marks R in the direction of measurement; X as an integer part or

designed as an integer multiple of the incremental graduation T on the scale M, so that the scanning of the code marks C ^^ and the reference marks R takes place in time with the scanning of the incremental graduation T «

According to Figure h are on a section of the scale

. M according to Figure 2 a reference mark R 'and assigned

^ η

£ 10 code stamps C ¹ , - C _ arranged in series.

j. nl η 5

These code marks C 'close depending on their code

■ nm

information with the positive measuring direction X an angle 0 ^ + 0C ₁ <90 ° or an angle 0 ^o <-et ₂ <-90 °

fine; the angle <£ .. is, for example, the code

! <15 formation "1" and the angle cC ₂ ^the code information

^M 0 "assigned. On the scanning reticle AP is a copy

touch field AC ¹ for the code marks C "- C ^f _

m n5 see that with the positive measuring direction X the

j angle Ct ₁ according to the code information "1! · includes ·

The scanning of the code marks C ¹ _Λ - C ¹ _ results

m n5

accordingly the binary combination "11010 ¹¹ for unambiguous identification of the associated reference _{mark R n} ^1. The code marks C ' _n1 - C" are also scanned by the scanning field AR for the reference mark R. Since the code marks C' _n1 - C ' _n according to their code information under the angles tf ₁ , el are arranged without gaps in the measuring direction X and since the width a «

of the code marks C, - C _ only part of the width b ¹

nl n5

the reference mark R 'perpendicular to the measuring direction X. is when the code marks are scanned

C ' _n1 - C ¹ only generates a DC voltage signal from the scanning field AR * in the assigned photo element, which enables the exact determination of the reference signal RS

not affected. The code signals CS » _H - CS ¹ "

nl η 5

¹ 't • <· f

are fed to the evaluation device in the Z counter. The scanning field AR ¹ matches the reference mark R 'and that which is integrated in the scanning field AR ¹

Scanning field AC with code marks C '

Code information "1" matches.

corresponding

The evaluation of the generated code signals CS,

CS ¹ takes place in the evaluation device of the counter nm

Ze This evaluation device can be a selection device contain, with the help of which certain references

from the series of reference marks

reference marks R,

R- R 'can be selected and brought into effect

can.

Claims (1)

- 10 claims 1 · Measuring device, in particular incremental measuring device, with reference marks provided along the graduation of a scale in the measuring direction, which are absolutely assigned to the graduation and on which, in cooperation with a scanning unit, reproducible electrical pulses are generated which act on a counter of the measuring device and / or a control device , characterized in that each of the identical reference marks (R) is serially assigned at least one code mark (C) (n, m = 1, 2, 3 ♦ ··) and that the code marks (C) in the measuring direction nm _ X follow one another without any gaps. 2. Measuring device according to claim 1, characterized in that the code marks (C) are arranged according to their code information transversely to the measuring direction X parallel to each other offset. \ 3. Measuring device according to claim 1, characterized in that the code marks (C ') are arranged at angles + it-, ' (Ji ₂ to the measuring direction X) in accordance with their code information. b » Measuring device according to claim 1, characterized in that the code marks (C) have, in addition to the identification features for the associated reference marks (R), at least information for completeness recognition. - 11 - 5 Measures ± nv ± ch.tiang according to. Claim. 1, characterized, in that ₉ are formed, the code marks (C) and the reference marks (R) as ganzzahligez "part or as a multiple of the ganzzaliliges Teiluiigsperiode the pitch (T) of the scale (m). 6. Measuring device according to claim 3 »characterized in that the" angle + <£., - "6 ₂ in areas 90 ° and 0 ° <- -90 lie.