JPS6359442B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for measuring a length by marking marks on the surface of a continuously running object such as a rectangular enamelled wire or a bare copper wire.

In the method of measuring a length by marking marks on the surface of a continuously running object, such as an electric wire, even though the marks are electrochemically harmless, it is desirable to wipe them off when measuring, and the precision of the measurement may be affected. Because the mark itself is small and has a very small amount, detection is performed by optically enlarging the mark. In this case, if the magnification of the optical system is increased too much, the range in which the mark can be detected without blurring, that is, the depth of field, will decrease in inverse proportion to the square of the magnification, which will prevent vibrations in the direction of the optical axis of the electric wire. This results in a decrease in detection sensitivity and the possibility of missing marks. Furthermore, if there are scratches or dust of the same size as the mark on the surface of the wire, the mark detection signal will be erroneously detected, which tends to significantly deteriorate the measuring accuracy. This means that the smaller the size of the mark compared to the size of the element of the detection sensor, the greater the influence of the background.

Normally, a method of mechanically supporting both ends of the wire in a short section is used to deal with the vibration of the wire, but it is also necessary to lower the magnification of the detection system and reduce the size of the sensor element to the size of the detection mark. There is also a method of obtaining a good S/N ratio and detecting even some vibrations by doing so.

On the other hand, as a method to remove the background effects on the wire surface, especially the effects of dust and scratches, dust and dirt are completely brushed off in the process before measuring.
A plurality of parallel output type sensors lined up in two rows are arranged perpendicular to the traveling direction of the wire to obtain differential (spatial differential) signals between each element with respect to the traveling direction of the wire, and the average signal of the background is used. A method is used to obtain mark signal pulses.

In addition, other methods are known, such as using a sensor that is sensitive to light of a specific wavelength in the detector itself, or using illumination with a slit-shaped light source to limit the range of background influence. .

However, there are dust and scratches of various sizes on the background of the actual wire surface, and if there is dust of the same size as a mark of about 100 to 200 μm, erroneous detection of the mark is unavoidable and it will be delayed. However, it has the disadvantage that practical measuring accuracy deteriorates.

The present invention aims to eliminate the drawbacks of the mark detection method in the prior art described above.The purpose of this invention is to detect only marks without erroneously detecting them even if scratches, dust, etc. on the surface are included in the background signal. The object of the present invention is to provide a method that can reliably detect and perform highly accurate measurement.

In order to achieve this objective, the present invention takes advantage of the irregular distribution of scratches, dirt, etc. on the surface and calculates it from the measurement time of the mark interval detected at a certain distance when measuring. By generating a timing gate signal for mark detection that is approximately equal to the mark interval corresponding to the traveling speed of the object being sought, and using a circuit configuration that receives the differential input signal from the detector only in this mark arrival section, it is possible to The mark detection pulse is obtained.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a mark detection method according to the present invention.

First, in the measurement method, an ink mark 2 of about 100 to 200 μm is printed on the surface of a continuously running object, for example, an electric wire 1, by a mark applicator 3 in response to a start signal, and this mark 2 advances as the electric wire 1 runs. When the light passes directly under the 2-line parallel output type linear sensor 7-a placed in the direction perpendicular to the direction, it is received by one of the elements via the optical system (half mirror 4, optical lens 5), and the light is sent to the opposite side of the linear sensor. The mark signal is detected by the differential signal between the two lines. Furthermore, when the mark passes directly under the second detector 7-b, the mark is detected using the same means, and the mark detection gate 17-b, which will be described in detail below, detects the mark.
a, 17-b, and detectors 7-a, 7-b.
constant distance ls between and mark interval li (start signal is from when a mark is detected by the second detector 7-b until the next mark is detected by the second detector 7-b)
The time interval measuring device 9 calculates the respective times ts and ti corresponding to
Find it by The marking timing of the mark applicator 3 is determined by the detector 7, regardless of the running speed of the electric wire 1.
Every time mark 2 is detected in b, approximately constant interval li
(including the flight time of the ink) is controlled at high pressure by the mark controller 12.

The above time data ts, ti are calculated by the calculator 10 at a linear velocity μ every time the mark 2 passes the second detector 7-b.
(=ls/ts) and mark interval li (=μ·ti) are calculated, and the measurement is performed until it becomes the measurement value ∠ (= _o 〓 ⁱ⁼¹ li).

Here, in order to ensure the reliability of mark detection, by increasing the number of picture elements of the line sensor, it is possible to prevent mark 2 from being missed due to variations in mark 2 and lateral vibration of wire 1, which is approximately ±1.6 mm. It is possible to absorb variations and lateral vibrations. In addition, in order to eliminate the influence of erroneous detection of scratches, dust, etc. on the surface of the electric wire 1, the speed data for each mark interval li obtained during measurement is used to
The frequency converter) 14 converts the frequency, and the frequency selection IC 15 classifies the range of frequency (or speed) changes into three stages based on the set values f ₁ and f ₂ as shown in Figure 2, and then outputs the output gate based on the speed. Signals can be obtained as shown in Fig. 2a, b, c.

The speed gate output signal of the frequency selection IC 15 is
They are not output simultaneously, the response time from input signal reception to output operation is 20 msec, and the maximum speed mark passing time ti is 60 msec or less.
Furthermore, the switching time for each output is approximately 2 μsec for both rise and fall, so there is no problem when switching the gate timing. This gate pulse is ANDed with the mark detection gate pulse from the one-shot circuit (FIG. 1 16) for obtaining the next mark detection gate signal from the mark signals detected by the detectors 7-a and 7-b. AND is taken at gate 17.

As a result, one of the mark detection gate pulses depending on the frequency (or speed) is selected. The width of the gate pulse for mark detection is several tens of times longer than the mark pulse to be detected, and can be varied within each width. interval of
The mark detection gate pulse can be generated while switching between D ₀ , D ₁ , D ₂ , and D ₃ .

D ₀ is the delay time of the gate pulse created by the first start signal.

Here, speed changes are divided into three stages, but in order to detect speed changes more finely, it is also possible to add a frequency selection IC 15, a one-shot circuit 16, etc., and use them in parallel.

Conventionally, when there is dust mixed in the background, for example, when a simple measuring scale is taken at 200mm intervals li on a 500m measuring scale L, the number of dust n similar to the mark is 10.
If it is detected at these locations, the measurement error will be (n-1) li/
L x 100 = 0.36%, and even in the method described above where the speed μ is determined between two points and then the mark interval li is determined from li = μ・ti, (1−n) li is obtained in the worst case under the same conditions. An error of /L×100=-0.36% occurs, and the higher the density of dust, etc., the worse the measuring accuracy becomes.

On the other hand, according to the present invention as explained above, only the detection mark can be reliably detected regardless of background dust, etc., so highly accurate metering can be performed, and the rise and rise of linear velocity can be Since it is possible to obtain a detection gate pulse that corresponds to the change in displacement during descent, reliable mark detection is possible and measurement accuracy can be improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of the measuring method according to the present invention, FIG. 2 is a diagram explaining the speed (frequency) switching timing of the method according to the present invention, and FIG. 3 also explains the mark detection gate timing. This is a diagram. 1: Running object, 2: Mark, 3: Mark applicator, 4: Half mirror, 5: Optical lens, 6: Illuminator, 7: 2-line parallel output type linear sensor, 8:
Differential amplifier, 9: Time interval measuring device, 10: Calculator, 11: Display device, 12: Cook controller,
13: DA converter, 14: VF converter, 1
5: Frequency selection IC, 16-a to d: One-shot circuit, 17: AND gate, 18: OR gate.

Claims (1)

[Claims] 1 Marks are attached to a continuously moving object at approximately constant lengths each time a mark is detected, and the marks are detected between two points a certain distance apart, and the time corresponding to the mark passing time between the two points and the mark interval is calculated. In this method, the marks are detected from the speed of the moving object determined at the time of measuring. A method for measuring a continuously running object, characterized in that a gate pulse for mark detection, which is approximately equal to the time required for detecting a mark, is generated from a start signal and a previous mark detection pulse, and this is ANDed with the detected mark signal.