JPH0429001A - Length measuring instrument for mobile object - Google Patents

Abstract

PURPOSE:To improve the accuracy of a length measurement value by arranging plural passage detectors for a mobile object on the movement path of the mobile object, finding the distances between those passage detectors previously, and finding the length of the mobile object based on those distances. CONSTITUTION:The laser beam oscillated by a laser device 7 is split by a beam splitter 8 into two beams, which are guided to transmission optical systems 10a and 10b through optical fiber cables 9a and 9b to irradiate one point on the mobile object 1. Scattered light on the object 1 is detected by a reception optical system 11 and guided to a photodetector 12 through an optical fiber 9c. The electric signal outputted by the detector 12 passes through an amplifier 13, a frequency tracer 14, and a frequency divider 15 to generate a pulse signal for measuring the moving speed of the object 1 from a Doppler signal. A gate circuit 6 finds the length L1 between a head detector (one of 17a-17n) and a tail detector 5 which detect the object 1. A pulse counter 4 finds the length L0 of the object 1 with pulse signals outputted by the circuit 6 and a frequency divider 15 and the length is outputted to a length display unit 20 for the mobile object.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to improving the accuracy of a moving object length meter that measures the length of a moving object using a moving object passage detector and a moving object speed detector.

[Conventional technology]

Conventionally, in a conveyance device that conveys an object by the frictional force of a conveyance roll rotated by an electric motor, etc., the length of the conveyed object, that is, a moving object, is measured by a length measuring roll placed on the conveyance device together with the conveyance roll. This method has been disclosed. For example, in Japanese Unexamined Patent Publication No. 53-79570, a device is placed on a conveying device. The number of pulses corresponding to the length of the moving object is counted by a detector for passing a plurality of moving objects, and a rotating pulse generator that generates pulses corresponding to the conveyance distance of the moving object. Using the distance between a plurality of passing detectors as a reference, the conveyance distance per pulse of the rotary pulse generator is determined for each length measurement, and the length of the moving object is determined by the counted number of pulses and the conveyance distance per pulse. A technique has been disclosed to measure the According to this method, even when a rotating pulse generator is attached and the diameter of the length measuring roll that rotates due to the frictional force with the moving object as the moving object is conveyed becomes smaller due to wear etc., the accuracy is correct. The length of a moving object can be measured. On the other hand, Japanese Patent Application Laid-Open No. 62-240805 discloses a technique relating to an optical length measuring meter that utilizes the laser Doppler effect according to the moving speed of a laser beam irradiated onto a moving object. In a length measuring meter that uses such a laser Doppler effect, the length of the moving object is measured using a length measuring roll that rotates according to the movement of the moving object and a rotating pulse generator. It is possible to solve the problem of errors caused by slips between the length-measuring roll and changes in roll diameter due to wear of the length-measuring roll.

Problem W1 that the Invention Attempts to Accomplish] However, in the above-mentioned Japanese Patent Application Laid-Open No. 53-79570, if the length of a moving object is much different than the distance between two passing detectors that serve as a reference for length measurement, an error occurs. There is a problem in that the amount increases. In particular, in the embodiment described in the specification of JP-A-53-79570, it is impossible to measure the length of the moving object if it is shorter than the distance between the two passing detectors. (This Japanese Patent Application Laid-Open No. 53-795
Therefore, in such a method for measuring the length of a moving object, it is difficult to measure the length difference Δ°C in the example of the specification of No. 70). It is not possible to measure the correct length of a moving object on the device.
Although the claim 70 mentions a plurality of passing detectors, the purpose of using the plurality of passing detectors is to obtain the travel distance γ per pulse. On the other hand, in JP-A No. 62-240805, the laser Doppler effect of a laser beam irradiated on a moving object is utilized.
The moving speed of this moving object is detected, and the length of this moving object is measured by integrating the moving speed during the passing period of this moving object.As the length of this moving object becomes longer, the measurement error increases. There is a problem that the error increases (the error is also integrated). The present invention has been made in view of such conventional problems, and is a moving object length measuring method that measures the length of a moving object using a moving object passage detector and a moving object speed detector. Accuracy of a moving object length meter that can prevent measurement errors from increasing even when the length of a moving object increases, without causing measurement errors due to slip or wear of the conveyor rolls involved in length measurement. The purpose is to improve.

[Means to achieve section group]

The present invention is a moving object length meter that measures the length of a moving object using a moving object passing detector and a moving object speed detector. ! a detector, a plurality of front end detectors for detecting passage of a disturbance object, a speed detector for a moving object, and a leading end detector for detecting a moving object without the moving object completely passing through the rear end detector; The length L between the front end detector and the rear end detector of
L2 is determined by integrating the signal from the speed detector after the most advanced tip detector detects the moving object until the trailing edge detector completely passes the moving object.
The above-mentioned problem has been achieved by providing an arithmetic unit that calculates the length of the moving object based on the sum of the length Ll and the length L2.

[Effect]

The present invention uses a length measuring roll that rotates as the moving object is conveyed and a rotating pulse generator directly connected to the length measuring roll, and measures the length of the moving object by counting pulses from the rotating pulse generator. In the measuring method, in order to eliminate measurement errors due to slippage between the moving object and the length measuring roll and changes in diameter due to wear of the length measuring roll, the movement disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 62-240805 is used. Problems that arise even when using a non-contact optical length measuring needle that uses the laser Doppler effect according to the moving speed of the object, that is, when measuring the length of a moving object based on the moving speed of the object. It solves the problems that arise. In other words, this method solves the problem that the measurement error increases as the length of the moving object increases with the method of measuring the length of the moving object by integrating the moving speed of the moving object over the transit period of the moving object. It is. In order to solve such problems, in the present invention, a plurality of passing detectors for a moving object are arranged on the moving path of the moving object, and the passing detector placed closest to the entrance side is placed at the rear end. In this method, the distance between these passing detectors is determined in advance, and the length of the moving object is determined using this distance as a reference. FIG. 1 is a diagram showing the length measuring method of the present invention. In FIG. 1, a moving object 1 is moving from left to right at a substantially constant speed. On the moving path of the moving object 1, a total of 15 moving object passage detectors, namely,
The rear end detector 5 shown in this figure, the shown front end detectors 17a, 171)-17j -x7h, and the unillustrated front end detectors 17c to 17i 17p to 1
7n are arranged at equal intervals of distance L× between the passing detectors. A moving object speed detector 30 is arranged at a position facing the tip detector 17a and slightly to the left of the tip detector 17a. In this figure, the moving object 1 has moved to a position where the tip fllla of the moving object is on the right side by a length longer than the tip detector 17j, and at this time, the rear end 1b of the moving object is on the right side than the tip detector 17j. It is in the position of vessel 5. Here, if the length of the moving object is Lo and the length from the rear end detector 5 to the front end detector 17j is Ll, the following relationship holds true. Lo = L j 10L 2 = 10XLX = L2 = - (1) Here, the measurement error of the moving object in the speed detector 30 is calculated as 0.0 of the moving speed detected by the speed detector 30. Assume that it is 1%. If such a moving object speed detector 30 is used, and if there are only two moving object passage detectors as in the conventional case, that is,
The measurement error Er+ of the length Lo of the moving object when only the rear end detector 5 and the front end detector 17a are used is as follows. 9xLx xo, 1% <lEr+l<LO
xLx xo, 1% (2) On the other hand, the error Er 2 when all 15 moving object passing detectors shown in Fig. 1 are used is of the first order. can be asked for. Among these passing detectors, mainly the rear end detector 5 and the front end detector 17" and 17 are used. When the moving object 1 does not pass through the rear end detector 5, the front end detector 17" is the most Suppose that it is detected to be a tip-to-edge detector. In addition to this, the length Lo of the moving object is as follows. 10X'LX <Lo<11xLx ・++++ <3
) That is, the length Ll is 10XL×. Furthermore, the length L2 from when the leading edge 1a of the moving object is detected by the most advanced leading edge detector 17 until the trailing edge 1b of the moving object completely passes the trailing edge detector 5 is mainly determined by the length L2 of the moving object. speed detector′
It is determined by 30.・These length Ll and length L2
The length Lo of the moving object is obtained by the sum of
The measurement error Er2 at this time is as follows. 0<l Er 21 <Lx xQ, 4%------
-(4) Comparing equations (3) and (4), the measurement error Er2 is one tenth of the measurement error Er+. That is,
As in the present invention, a plurality of front end detectors are arranged, and the rear end detector 5 is connected to the most advanced front end detector 17j that detects the moving object 1 without the moving object 1 completely overshooting. By measuring the length of the moving object 1 with reference to the length Ll between the moving object 1 and the rear end detector 5, it is possible to eliminate the error that increases as the length of the moving object 1 becomes longer. Note that the speed detector 30 of the moving object 1 used in the present invention
4. The present invention is not limited to the non-contact optical velocity detection force method using the laser Doppler effect as described above. In addition, the present invention does not limit the number of installed tip detectors or the installation interval. For example, when measuring the length of three types of products and inspecting these products. , it is sufficient to install three tip detectors corresponding to these three types of lengths. At this time, the three types of lengths Ll are (product target length)
- (If you install these three tip detectors so that the length is slightly shorter than the passing deviation, you can improve the inspection accuracy and
Even if the length of the product is shorter than the length 1 corresponding to this product, which causes a measurement defect, there will be no problem in inspection since this is a rejected product in the first place.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings. FIG. 2 is a configuration diagram of a length meter for the moving object 1 to which the present invention is applied. In FIG. 2, the moving object 1 is moving from left to right at approximately constant speed. Fifteen moving object passage detectors are arranged on the moving path of the moving object 1. Among these passing detectors, the one disposed closest to the entrance side of the length meter is the rear end detector 5, which is successively followed by tip detectors 17a and 17b, and further tip detectors 17C to 171 (not shown). A tip detector 17n is arranged. The length of the interval between the rear end detector 5 and the front end detector 17a is La, and the length of the interval between the rear end detector 5 and the front end detector 17a is La.
The length of the interval between 7a and the tip detector 17b is Lb,
Furthermore, the lengths of the intervals between the tip detectors 17b, 17c to 17n thereafter are respectively LC to Ln in order. The laser beam oscillated by the laser device 7 is split into two by the beam splitter 8. The two divided laser beams are guided to transmission optical systems 10a and 10b by optical fiber cables 9a and 9b, respectively. Moving object#
-1 point on 1 is irradiated with laser light by the two transmitting optical systems 10a and 10b, but at this time the transmitting optical system 10
The angle between the optical path of the laser beam from a to the surface of the moving object 1 and the optical path of the laser beam from the transmission optical system 10b to the surface of the moving object 1 is configured to be an angle φ. The scattered light of these irradiated laser beams on the moving object 1 is detected by the receiving optical system 11 and guided to the photodetector 12 by the optical fiber 9C. The laser beam guided to this photodetector 12 is
2, the electrical signal is amplified by an amplifier 13, and the amplified electrical signal is input to a frequency tracker 14. The electrical signals input to this frequency tracker 14 include a DC signal proportional to the intensity of the received light and an AC signal (hereinafter referred to as
Doppler signal) exists. The frequency tracker 14 and frequency divider 15 generate a pulse signal for measuring the moving speed of the moving object 1 from this Doppler signal. The pulse signal according to this moving speed can be changed to any unit by a setting switch 16. The gate circuit 6 connects the rear end detector 5 to the most advanced front end detector (any one of 17a to 17nt) that has detected the moving object 1 without the moving object #l completely passing over the rear end detector 5.
The length Ll between the rear end detector 5 and the rear end detector 5 is determined. The pulse counter 4 determines the length Lo of the moving object 1 using the pulse signal output from the aforementioned gate circuit 6 and the aforementioned frequency divider 15, and sends the determined measurement value to the moving object length indicator 20. This is what is output. The moving object length indicator 20 displays the input measurement value numerically so that the operator can visually see it. At this time, the pulse counter 4 selects the tip detectors 178 to 1 according to the input from the tip detector correction setting switch 18.
7n detection delay is corrected to improve accuracy. This tip detector correction setting switch 18 is a Diq switch S.
The tip detector correction value α is set using W1 to SWn. The effects of the embodiment will be explained below. At the moment when the tip 1a of the moving object 1, which moved from the left and was carried into the length meter of moving object #1, passes the tip detector 17a, the pulse counter 4 receives the length La by the gate circuit 6.
is set, and after this, the pulse counter 4 detects the moving object 1.
This length measurement value is updated by a pulse signal from the frequency divider 15 in accordance with the moving speed of. Further, when the moving object 1 moves and the tip 1a of the moving object 1 reaches the tip detector 17b, the gate circuit 6 forcibly changes the length measurement value in the pulse counter 4 at the moment of this arrival. After that, the pulse counter 4 updates the length measurement value in the pulse counter 4 by inputting the pulse signal from the frequency divider 15 according to the moving speed of the moving object 1. I will do it. In this figure, the length Lo of the moving object 1 has the following relationship with the lengths La to Ln of the intervals between the rear end detector 5 and the 14 front end detectors 17a to 17n. be. La 10Lb <Lo<La fLb 10LC-(5)
Therefore, as the moving object 1 moves further to the right, before the tip 1a of the moving object 1 reaches the tip detector 17c,
The rear end 1b of the moving object 1 reaches the rear end detector 5. At the moment when the rear end of the moving object 1 @1b reaches the rear end detector 5, the gate circuit #I6 sends the pulse counter 4 to the pulse counter 4 for length measurement using the pulse signal from the frequency divider 15. Outputs a signal to stop updating the value. Further, in response to this stop signal, the pulse counter 4 finally determines the length measurement value of the length Lo of the moving object 1, and outputs this to the moving object length indicator 20. The length measurement increment updated in the pulse counter 4 according to the pulse signal output from the frequency divider 15 after the tip 1a of the moving object 1 passes the tip detector 17b, ie, the most advanced tip detector, is: This is the same length as the aforementioned length L2. Therefore, the length Lo of the moving object 1 at the time when the moving object 1 passes the rear end 1b or the rear end detector 5 and the length measurement value in the pulse counter 4 is finally determined can be expressed as follows. can. Lo=La fLb 10 L2 -...- (6) However, due to the detection delay of the passing detector of the moving object 1 and the processing delay in the gate circuit 6, pulse counter 4, etc., the pulse counter 4 by the gate circuit 6 described above A timing error proportional to the speed of the moving object 1 occurs when the length La and the length Lb are forcibly written to. The tip detector correction setting switch 18 is set with a tip detector correction value α for correcting this error, and the pulse counter 4 is set to the tip detector correction value α that corrects this error.
The length Lo of the moving object 1 is determined using this tip detector correction value α and the following equation instead of using equation 6). Lo=(La + Lb)Xα+L2·= (7) Note that if this timing error is constant and independent of the moving speed, the following equation is used instead of equation (7). Lo=La+Ltl+L2+α...
(8) In this way, in this embodiment, a plurality of tip detectors 1
7a to 17n, one of the most advanced tip detectors that detected the tip 1a of the moving object 1 without the moving object 1 completely passing through the rear edge detector 5 and the rear end. The length Ll between the moving object 1 and the detector 5 is determined, and the length of the moving object is determined using the speed detector 30 of the moving object 1 using this as a reference. By measuring , it is possible to eliminate errors that tend to increase as the length of the moving object 1 increases. Effects of the Invention As explained above, according to the present invention, the length of the moving object is measured by the passing detector of the moving object and the speed detector of the moving object. In a length meter, there is no measurement error due to slip or wear of the measuring roll involved in length measurement, and the movement increases as the length of the moving object increases! i! It is said that it is possible to prevent an increase in the measurement error that occurs in the length measurement value of a moving object calculated from the velocity detection value of the I-body, and thereby improve the accuracy of the length measurement value. .

[Brief explanation of drawings]

FIG. 1 is a diagram showing the length measuring method of the present invention, and FIG. 2 is a configuration diagram of a length meter for a moving object to which the present invention is applied. DESCRIPTION OF SYMBOLS 1... Moving object, 1a... Tip of moving object, 1b... Rear end of moving object, 4... Pulse counter, 5... Rear end detector, 6... Gate circuit, 7. ... Laser device, 8... Beam splitter, 9a, 9b, 9c... Optical fiber cable, 10a,
10b--Transmitting optical system, 11--Receiving optical system, 12--Photodetector, 13--Amplifier, 14--Frequency tracker, 1--Frequency divider, 16. ... Setting switch, 17a to 17n... Tip detector, 18... Tip detector correction setting switch, 20... Length indicator of moving object, 30... Speed detector of 15 moving objects, Lo...8 Length of the moving object, Ll...Length from the step detector to the most advanced tip detection P, L2...The tip of the moving object is detected by the most advanced tip detector The distance between the detectors, α...
・Tip detector correction value.

Claims (1)

[Claims] (1) A moving object length meter that measures the length of a moving object using a moving object passage detector and a moving object speed detector, which includes a rear end detector that detects the passage of a moving object; a plurality of front end detectors for detecting the passage of an object; a speed detector for a moving object; and the most advanced front end detector that detects a moving object without the moving object completely passing over the rear end detector. and the rear end detector, and transmits the signal from the speed detector until the most advanced tip detector detects the moving object, and then passes the rear end detector to the rear end detector until the moving object is completely detected. Find the length L_2 by integrating until it goes too far, and this length L_1
and an arithmetic unit that calculates the length of the moving object by the sum of the length L_2 and the length L_2.