DE1238679B - Digital evaluation stage for a width measuring device - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

GOIb

German KL: 42 b - 5

Number: 1238 679

File number: L 49180 IX b / 42 b

Filing date: November 3, 1964

Opened on: April 13, 1967

The invention relates to a digital evaluation stage for a width measuring device.

There are already known measuring devices that define a calibration distance with the help of photocells and cause the counting of pulses from an encoder when they respond: or stop counting. Measuring devices of this type, however, are used in particular for length measurement.

There are also already known measuring devices with a single. Rotary beam scanner the width z. B. measure of rolling stock. In these measuring devices, however, the so-called sagittal error occurs.

Also known 'measuring devices with the aid of television cameras are generally very expensive.

Another known method for photoelectrically determining the relative position at least an edge of a material to be measured which is noticeably different from its surroundings in terms of its brightness by means of a rotary beam probe is that the phase position of the inserts of measuring pulses relative * to a matching pulse sequence of the same frequency as a criterion for determining the position of the object edge is used and that the two pulse trains one at its output a square-wave Alternating current ^ supplying pulse generators are supplied in such a way, -Measure the direct current mean value of the alternating current serves as a measure for the deviation of the object edge from a nominal position. The disadvantage of this measuring method is that the measuring accuracy is increased by the DC averaging is limited and a digital display of the measured value is not possible. : ': iffi- "'

It is also known, for. B. in the case of frequency measurements, the vibrations ^; wtiäi iüfi known frequency via a current gate, which is controlled for the duration of a normal time supplied by a time base, and a downstream reduction circuit to a counter that stores the number of oscillations and displays it in digits.

The aforementioned disadvantages are due to the digital evaluation stage for a width measuring device, in which two rotary beam scanner in a line perpendicular to the direction of movement one with regard to its Brightness of its surroundings noticeably contrasting material to be measured are arranged over the edges and in which the rotary beam scanner, in addition to the measuring pulses, has a comparative pulse sequence of the same type Supply frequency, avoided according to the invention in that the comparison pulses a control unit key in such a way that this alternating gate circuits downstream of the rotary beam scanners to the passage Digital evaluation stage for a width measuring device

Applicant:

Licentia Patent-Verwaltungs-G. m. b. H.,

Frankfurt / M., Theodor-Stern-Kai 1

Named as inventor:
Dipl.-Ing. Karl van Kaick, Berlin

of the measuring pulse following the comparison pulse opens, that these gate circuits further gate

■ 5 circuits are arranged downstream of the measuring pulses and for their duration in a known manner for the counting pulses coming from an oscillator are opened, which in turn in a known manner via a frequency divider in a Run in counter with subsequent memories with digital output for a digital display, but in such a way that that the counter is preset to the complement of the scanning width of a rotary beam scanner. ν -ι

The invention is explained in more detail below with reference to drawings. In the described Embodiment is to measure the width of a sheet, but the invention can also be other width measurements may be used. ■ s During one revolution of a rotary jet button of known design, as many measurements can be made as a polygon mirror has surfaces. At the start A synchronous pulse is generated inductively for each measuring period (magnetic pulse). During the measuring period, the photo cell is then illuminated over a surface of the polygon mirror, which thereby supplies a signal, the length of which corresponds to the duration of the lighting. Provided of a small measuring angle is the duration of the light signals the length of the within the measuring angle detected red-hot material proportionally.

In Fig. 1 the sync pulse is represented by the triangular pulse and the light pulse by the trapezoidal pulse. The measuring period extends from the end of one light pulse to the end of the next.

The duration and repetition frequency of the measuring period can be determined by the speed and number of areas of the Polygon mirror in the rotary beam scanner can be adapted to the respective needs.

For measuring the width of a red-hot sheet metal strip or its deviation from a nominal width two rotary beam sensors 1 and 2 - as in

- ; ■■ 709 549/189

Claims (4)

F i g. 2 can be seen - combined. They are retracted manually or automatically to the nominal width B of the sheet 3. Each rotary beam sensor now supplies light pulses, the length of which is proportional to the detected red-hot material width, i.e. (5 - S ') or (S - 5 "'). It is assumed that both buttons have the same speed. A control unit 4, stimulated by the magnetic pulses of the rotary beam scanner, now ensures through two gate circuits 5 and 6 that the rotary beam scanner are interrogated alternately and that there are always as many pulses from an oscillator synchronized with their speed via gate circuits 8 and 9 as well as a scale correction element 10, e.g. A frequency divider can run into a counter 11, as corresponds to the recorded distances of the two rotary beam sensors. If the counter is already preset to the complement of the distance S to full counter capacity, ie to (- S) , the value S '+ S "- S = - AB remains in the counter at the end of the measuring period, ie after the two buttons have been interrogated stand. The value5 is then converted into a with the correct sign Memory 12 taken over, where it is in digital form (for further processing or for digital displays) is available. The counting of the measuring periods takes place at the control unit 4. From this control unit, after each Measurement also the signals for the transfer of the result to an output memory 13 and for the Deletion or presetting of the counter via line 14 is given. After a complete measurement, it is checked whether the counter reading is still below the full counting capacity lies. If this is the case, the result is negative and must be output as a complement. If the counting capacity has been exceeded, then another flip-flop 15 has flipped over and the result is positive and is stated directly. The result can be taken from the digital output 16. The digital results can also be converted into an analog form for control and regulation tasks will. For this purpose, the circuit is supplemented by a digital-to-analog converter, a comparator and an analog output required. environment noticeably lifting material to be measured are arranged over its edges and in which the Rotary beam sensors deliver a comparison pulse sequence of the same frequency in addition to the measuring pulses, characterized in that the comparison pulses key a control device (4) so that this alternately the rotary beam sensors (1, 2) downstream gate circuits (5, 6) to the passage of the measuring pulse following the comparison pulse opens this gate circuit (5, 6) further gate circuits (8, 9) are arranged downstream of the measuring pulses and for their Duration opened in a known manner for the counting pulses coming from an oscillator (7) are, in turn, in a known manner via a frequency divider (10) in a Run in counter (11) with subsequent memories (12, 13) with digital output for a digital display, but in such a way that the counter is based on the complement of the scanning width of a rotary beam scanner is preset. 2. Digital evaluation stage according to claim 1, characterized in that the query of the button for averaging is repeated η times and the pulse train is reduced by the factor η . 3. Digital evaluation stage according to claim 1 and 2, characterized in that the result represents the negative difference between the nominal and actual widths and the associated memory is entered with the correct sign using a flip-flop. 4. Digital evaluation stage according to claim 1, characterized in that the two, the deviations partial pulse trains proportional on both sides are not counted one after the other, but simultaneously in the counter. 5. Digital evaluation stage according to claim 4, characterized in that with simultaneous counting a coincidence lock is switched in front of the counter. 6. Digital evaluation stage according to claim 4, characterized in that to avoid Coincidence used for both queries synchronous but 180 ° phase-shifted pulse trains will. Claims: _{Publications considered} : 1. Digital evaluation stage for a width measurement German Auslegeschrift No. 1191591; advises which two rotary beam sensors in a Rohde & Schwarz-Mitteilungen, No. 9/1957, Line perpendicular to the direction of movement of a 50 p. 100 to 104; in terms of its brightness from its um- ATM, Liefer 342, July 1964, pp. 157 to 160. For this purpose Ί sheet of drawings 709 549/189 4.67 © Bundesdruckerei Berlin