JPS58191908A - Length measuring device of band-shaped material to be carried - Google Patents

Abstract

PURPOSE:To improve the precision of length measurement, by using two photodiode array cameras and selecting measured values at the time when the difference between the timing of acquisition of the front edge of a band-shaped material due to the lower-side camera and that of the rear edge of the band- shaped material due to the upper-side camera is minimum and defining the addition value as a length measured value. CONSTITUTION:Photodiode array cameras 1 and 2 are arranged along a carrying path of a band-shaped material T1 above a conveyor 6, and an operating device 5 is provided. Measurement signals or the like issued from both cameras 1 and 2 are operated to select measured values at the time when the difference between the timing of acquisition of the front edge of the band-shaped material T1 due to the lower-side camera 1 and that of the rear edge of the band-shaped material T1 due to the upper-side camera 2 is minimum, namely, at the time when both edges are acquired almost simultaneously, and the addition value based on these measured values is defined as a length measured value L of the band-shaped material T1. Thus, the inevitable error due to movement of the moving band-shaped material T1 is reduced to the minimum.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a sub-length bag that accurately measures the length of a strip conveyed at high speed on a conveyor without contact using photoelectric conversion.
Regarding the configuration of

Recently, photodiode array cameras are often used to measure the length of moving strips.

For example, in the tread extrusion process on a tire production line, tread members are extruded from an extrusion device and cut into fixed lengths, and as they are transported on a conveyor at intervals, the length of each tread member is measured without stopping the transport. It is used when

This type of length measuring device has a high resolution camera, so it is possible to measure length with a fairly high-precision I boat, but a photodiode camera (
Since the strip moves during one scanning period with the camera (hereinafter abbreviated as camera), it is impossible to avoid the measurement error caused by the maximum amount of movement. The question of whether to do so was considered a serious issue.

There are two types of conventional length measuring devices of this type: one that uses one camera (see Figure 3) and one that uses two cameras (see Figure 4). The front edge of the conveyed strip (T2) is detected by the optical direct conversion type detection means (,2
, 0: 'i (see Figure 3 B)) The photoswitch α of the detection means a and 3u sends a signal to the camera (]]) to start scanning and measure the length. There is (
(See Figure 3(f))).

During this length measurement, the strip (T2) is always moving at a speed of Body (T
2) moves by ll-Δtv.

The camera (11) that started scanning detects the trailing edge of the strip (T2) and sends the number of light-shielded elements in the group of photoelectric conversion elements to a processor (not shown). is this value and the offset amount input in advance (4o'
) and output this as the measured length of the strip (T2).

By the way, if you compare Figure 3 (0) and Figure 3 (C), it is clear that the band-shaped body (
While detecting the trailing edge of T2), the strip (T2)
el'-e+), so the measured value is actually 1
It is shorter than the length of 4, and this becomes an error.

Now, if the scanning speed of the camera (11) is (v), the maximum value of the error is ), the photo switch 124) emits a signal when the light is blocked by the front edge of the
．． <1. ), the camera (211°2) starts scanning, as shown in Fig. 4 (b), the camera processing on the lower side (l) is in the advancing direction of the strip (T3), and the scanning direction on the lower side is in the direction of movement of the strip (T3). The side camera (four is in the opposite direction to the movement of the strip (T3)).

When the camera (22) captures the rear edge of the strip (T3), the camera (22) inputs the number of built-in optical direct conversion elements that are blocked at that time to a processor (not shown), and processes the The vessel thereby calculates the length 42') shown in Figure 4 (b).

On the other hand, when the camera 1.21) captures the front edge of the strip (T8), the camera 1.21) inputs the number of light 4 conversion elements that are blocked at that time into the processor; The length lt') shown in FIG. 4(c) is calculated, and this value is expressed as lu (1?2'), and the offset length lt', which has been input in advance, is calculated. o) and outputs the sum as the measured value of the strip (T3).

In this case, the measured value of the length of the strip is 7?1'mo#o+12'=≠'yv1lo+ev, and the maximum value of the error is, for example, the moving speed of the strip 60m7c ( V= 1run/
m5ec) camera, 21i, 122) measurement range
100mm camera + 21), 1:22) number of elements
1,000 pieces scanning cycle 1m5/
Scanning photoswitch (24) response delay △22m
The value of the error for the case of 5et is the camera (21)
,・22) From the values of measurement range, number of elements, and scanning period, the scanning speed is V = 100 m/m5, and from equations (a) and (0) in item n, the maximum for one camera is The error is -2,99ma+, while the maximum error with two cameras is lL -12
= -5()-50+u+, 1L+772=
When 5 points and 15 axes m, it becomes 90 degrees 5 degrees.

In view of the fact that conventional devices have been unable to avoid measurement errors of a certain magnitude, the present invention has been made in order to eliminate such drawbacks, and to avoid the unavoidable measurement errors during measurement. An object of the present invention is to provide a length measuring device that can significantly reduce the error caused by the above-described problems. The two cameras are provided above the conveyance path of the strip, at the upper and lower sides of the conveyor in the running direction of the conveyor, and with the scanning direction parallel to the conveyor's running direction, and Back and forth above 2
The length measurement area is arranged such that a predetermined interval of values related to the length of the strip is maintained between the two length measurement regions, and the portion connected to the front edge of the strip that exists within the length measurement region with the camera on the lower side. The length is measured, and the upper camera measures the length of the portion extending to the rear end edge of the band existing within the length measurement area, while the arithmetic unit uses the measurement (M The sum of the three values of the signal corresponding to the signal and the predetermined gap is +iil
This is done every scan based on the synchronized operation command sent to both recording cameras, and among the summation results, the summation value when the difference in the timing of capturing the front edge and rear edge of the strip is the smallest is selected. The structure is characterized by the following structure, thus reducing length measurement errors as much as possible and increasing accuracy.

Hereinafter, one example of the device of the present invention will be explained in detail based on the attached drawings. In Fig. 1, (Tl) is a strip-shaped body, and the longitudinal side is the traveling line of the conveyor (6) (the direction line indicated by the white arrow). (1) and (2) are photodiode cameras, which are conveyed by the conveyor (6) at high speed.
above the conveyor path of the conveyor (6), the conveyor (6) is arranged in front and behind the lower and upper sides in the running direction of the conveyor (6).
1, "Each length measurement area (ml) in the conveyance path, (
m2) can be imaged.

+3) and (4) are the cameras (1) and (2), respectively.
) is a signal processor, and (5) is an arithmetic device such as a microcomputer. (1!o) is the measurement area d (ml
), (77Z2) at a predetermined interval determined by the length of the strip (T1).

Also, (I) I ), (D2 ) are camera (t), (
2) is the number of light-shielded elements among the optical direct conversion element group, and is (αl).

(α2) are the scaling coefficients of cameras (1) and (2), respectively.

The cameras (1) and (2) are activated at the same time and are scanned at a constant speed (v) much faster than the speed M of the strip (T1), and each scanning direction is controlled by the conveyor. The camera (1) on the lower side is installed parallel to the traveling direction of (6), and the length of the portion connected to the front edge of the strip (Tl) is determined by the number of photoelectric conversion elements (Dl) that are shielded from light. Therefore, the scanning direction is set to the band-shaped body (Tl
) according to the running direction.

On the other hand, the upper camera (2) is designed to measure the length of the part extending to the rear edge of the strip (TI') as the number of photoelectric conversion elements (D2) that are shielded from light. The scanning direction is opposite to the traveling direction of the strip (T1).

Note that the cameras (1) and (2) are activated simultaneously and start scanning by a synchronous operation command from a controller (not shown), and once the scanning has completed one cycle, the scanning is repeated again from the starting position (1). 1:), (D2) are formed so as to measure the length continuously, while the predetermined interval (lO) is such that the front edge and the rear edge of the strip (T1.) are formed so that the length measurement area ( ml) and (m2)
The length of the band-shaped body (T1) is L) since it is desirable that the band-shaped body (T1) simultaneously exist in
The following relationship holds true: L > lo > L - (ml 10 m2).

Next, the calculation device (5) in 14U processes the measurement signals from the signal processors (3) and (4) according to the calculation flow sheet shown in FIG. 1
During the scanning period, the measurement signal (Dl) of the camera (1) is (
αl) and the measurement signal of camera (2) (D2)
(α2) multiplied by the offset length (lo), this value is stored as the length of the strip (T1), and the most appropriate one is selected from these stored values. The camera is configured to perform arithmetic processing using this as a measured value, and the appropriate values include the time when camera (1) captured the leading edge, the time when camera (2) captured the trailing edge, and so on. The sum value when the deviation is the smallest is the corresponding value. For example, in Figure 4 (a), when 11 and 12 are equal, that is, when the front edge and the rear edge are detected at the same time, the length measurement It is easily understood that the measurement error is minimized because no timing deviation occurs.

When the length measuring device configured as described above issues a synchronized operation command to start scanning (31) to cameras (1) and (2), every time scanning is performed, the length measuring device Measurement signals (Dl) (D2) are emitted and input to the arithmetic unit (5). The front edge of the 34° strip (T1)
) has arrived within the length measurement area (ml) of DI':>0
Judgment (33) is made based on D2<number of sensor bits of camera (2) to determine that the trailing edge of this strip (T1) has arrived within the length measurement area M (m2) of camera (2) ( Then, if we further determine that the condition ID1→21<β (β is a constant) is satisfied, then αlDl+
α2D2 +1. Perform the summation j36) and memorize it.

This calculation is performed every time scanning is repeated, and the one with the smallest difference between the time when Dl is measured and the time when DIG is measured is selected (DI-=-D2), and this is used as the strip (Tl). The measurement length shall be .

This allows ll-12 to be minimized in the above equation (0), making it possible to greatly reduce the error.

For example, if we calculate the case corresponding to the calculation example using the formula (to) above, it is easy to calculate 1111-12-=1, so we take 11.12 to the full length measurement range and ll +12 = 200. Even if it is mm, from formula (b)), the error is +0.03mm and -0,01711+
It becomes I+.

Although it depends on the resolution of cameras (1) and (2), in practical terms it is easy to keep to below 1nrm.
Compared to the maximum error of ±O,"rmm in the conventional two-force mela method, it is less than 2000, which improves the length measurement accuracy.

As is clear from the above description, the present invention uses two photodiode array cameras (1) and (2) to determine the time taken to capture the front edge by the lower camera (1) and the time taken to capture the front edge by the lower camera (1). Compare the time when the trailing edge is captured by camera (2) and select the measured value when the difference is the smallest, that is, when the leading edge and trailing edge are captured almost simultaneously, and calculate the sum based on this value. Since the calculated value is used as the length measurement value of the strip (TI), even though the strip (Tl) is moving, it is possible to minimize the inevitable error in length measurement due to this movement. This makes it possible to significantly improve length measurement accuracy, and as in the previous example, the error range can be reduced to ±0.
．． Highly accurate length measurement of approximately 1 fl is possible.

[Brief explanation of drawings]

Fig. 1 is a schematic structural diagram of an example of the device of the present invention, Fig. 2 is a flowchart of the arithmetic unit used in the device shown in Fig. 1, and Figs. Illustration diagram, 4th
Figures P) to (C) are schematic explanatory diagrams of other examples of conventional length measurement values d. (1), (2)...Photodiode camera5.
(5)...Arithmetic unit, (6)...Conveyor, (T1
)...Band Book Figure 1 Figure 2 Figure 3- (8) Figure 4 (A) (0) (8)

Claims (1)

[Claims] 1. A strip (TI) whose longitudinal side matches the running line of the conveyor (6) and is conveyed at high speed by the conveyor (6).
It is a device that measures the length of the strips (T1), and is started at the same time and repeatedly receives a synchronous operation command to scan at a uniform speed that is much faster than the transport speed of the strip (T1).
photodiode array cameras (1), (2)
and an arithmetic unit (5) that receives measurement signals emitted by both cameras (1) and (2) and performs predetermined arithmetic processing, and consists of two photodiode array cameras (1). (2) are provided above the transport path of the strip (T1) at the upper and lower sides of the conveyor (6) in the running direction, and with the scanning direction parallel to the running direction of the conveyor (6). At the same time, L>
The camera (1) on the lower side is arranged so that a predetermined interval (io) is maintained within the range of eo > L -- (7711 mm2) (L: length of the strip (T1)). The length of the part that extends to the front edge of the strip (Tz) is measured as the number of photoelectric conversion elements that are shielded from light. The length of the continuous portion is measured as the number of photoelectric conversion elements that are shielded from light. On the other hand, the arithmetic unit (5)
1). (2) respectively emit measurement signals and the predetermined interval (/!
The summation of the three values of the signals corresponding to o) is performed every scan by the synchronous operation command, and among the summation results, the front edge and rear edge of the band-shaped body (T1) are calculated. 1. A length measuring device for a belt-shaped object to be conveyed, characterized in that the summed value when the difference in captured timing is the smallest is selected and arithmetic processing is performed to use this as the measured value.