JPH06109448A - Dimension measuring method - Google Patents

Abstract

PURPOSE:To accurately measure a shape without allowing freight to fall in the gap between rollers by placing the freight on a transparent plate sufficiently larger than the freight in the advance direction of the freight to transfer the same on conveyor rollers. CONSTITUTION:Freight A is placed on a transparent plate 5, for example, an acrylic resin plate to be transported on drive rollers 1. At the time of the measurement of dimensions, beam 4c transmits through the plate 5 from a floodlight projector 4a to be detected by a light receiving device 4b provided under the rollers 1. When the freight A advances in the direction shown by an arrow right-angled to the rollers 1, the beam 3c between a light projecting element 3a and a photodetector 3b is temporarily blocked with the advance of the freight A. Therefore, when the rotational speeds of the rollers 1 are constant, the length of the freight A is instantaneously calculated from the moving speed of a conveyor and the light blocking time. Since the freight A is placed on the sufficiently large transparent plate to be transported, the freight A does not fall in the gap between the rollers 1 even when the interval between the rollers of the conveyor is wide and the dimensions of the freight can be accurately measured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dimension measuring method capable of accurately measuring the shape of a cargo even when the gap between the rollers is large relative to the length of the cargo.

[0002]

2. Description of the Related Art Various methods for contactlessly measuring the length and width of a rectangular parallelepiped cargo being transferred on a conveyor are known, but the most general method is by optical means.

[0003]

However, in this type of method, although there is no problem when the cargo placed on the conveyor is relatively large, it can be measured, but when the cargo is small, the length L is particularly short. Since it is difficult to move linearly by falling between rollers, it is difficult to measure the length and width correctly.

For example, as shown in FIG. 5, the length L of the cargo A is
When there is more than twice the distance between the rollers 1, there is almost no problem in conveyance or measurement. However, as shown in FIG. 6, when the length L is short, the cargo A easily falls between the rollers 1, and particularly when the measuring light flux passes between the rollers 1, it becomes fatal in measurement. Further, as shown by the dotted line in FIG. 6, even when a belt conveyor is used, similar results are obtained if the roller interval between the belts is large.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks of the conventional apparatus and to provide a dimension measuring method capable of accurately measuring the dimension without dropping the cargo even when the rollers of the conveyor are large.

[0006]

The dimension measuring method according to the present invention for attaining the above-mentioned object, in the case of measuring the shape of a cargo being transported on a roller of a conveyor, is at least in the traveling direction of the cargo. Is placed on a sufficiently large transparent plate, the cargo is transported on the rollers, and the shape of the cargo is optically measured using projection light in the vertical direction of the cargo passing through the transparent plate. It is characterized by

[0007]

In the dimension measuring method having the above-mentioned structure, the shape is accurately measured without placing the cargo between the rollers of the conveyor by placing the cargo on the transparent plate.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to FIGS. 1 to 4 on the basis of an embodiment for measuring the length and width of a cargo traveling on a conveyor while being inclined.

In FIG. 1, a large number of drive rollers 1 are arranged in parallel, and a rotary encoder 2 for detecting the rotation angle of the drive roller 1 is attached to one of them. An optical sensor including a light projecting element 3a and a light receiving element 3b is provided above the driving roller 1 at a position where the light flux 3c is blocked by the cargo A. The light flux 3c is oriented in a direction orthogonal to the traveling direction of the cargo A. Further, a projector 4a composed of a number of elements is arranged above the drive roller 1 in parallel with the drive roller 1 in a straight line orthogonal to the traveling direction of the cargo A so that the light beam 4c is projected onto the cargo A. The light receiver 4b is disposed between the drive rollers 1 in parallel with the light projector 4a.

Then, the cargo A is placed on a transparent plate 5 such as an acrylic plate and carried on the drive roller 1. The output of the rotary encoder 2 and the light blocking states of the light beams 3c and 4c are input to an arithmetic processing unit (not shown) so that necessary arithmetic operations can be performed. Further, the length of the transparent plate 5 is preferably twice or more the distance between the drive rollers 1.

When measuring the luminous flux 4c from the projector 4a,
As shown in FIG. 2, the light passes through the transparent plate 5 and is received by the light receiver 4b below. When the cargo A travels in the direction of the arrow perpendicular to the driving roller 1, the light projecting element 3a and the light receiving element 3b.
The light flux 3c between them is temporarily shielded as the cargo A advances. The light blocking starts when the front end of the cargo A, for example, a corner A1 of the front edge of the cargo A crosses the light beam 3c, and the light blocking ends when the trailing edge A2 crosses the light beam 3c.

If the rotation speed of the driving roller 1 is constant,
The length L of the cargo A can be immediately obtained from the conveyor moving speed and the shading time. Alternatively, the rotation angle of the rotary encoder 2 attached to the drive roller 1 during the light blocking period may be adopted as the length reference, or the length measurement accuracy may be improved by using a plurality of reference light beams. You can also

However, when the cargo A advances obliquely with respect to the drive roller 1 when viewed from above, the true length L cannot be obtained. Further, the projector 4a is replaced by the light receiver 4b.
Since the light beam 4c is projected on the vertical plane through the transparent plate 5 toward the target, while the cargo A is passing through this light flux surface, the cargo A
The number of light beams 4c proportional to the width of the light is blocked, and the width of the cargo A is obtained from the output from the light receiver 4b. However, as in the case of the length measurement, the obtained value is not the true width but the apparent width. Width.

FIG. 3 is an explanatory view of the procedure for calculating the inclination angle θ when the cargo A is traveling while inclining as viewed from above,
In FIG. 3A, after a short time after the front end A1 of the cargo A passes through the vertical light flux surface 4c portion, the distance d1 between the side surface of the cargo A intersecting the light flux 4c and the reference line S is first measured. Actually Figure 1
As can be seen from the above, the distance d1 is immediately obtained from the number of transmitted vertical light beams 4c in one lateral direction of the cargo A.

Next, when the cargo A travels the constant distance a after the measurement of the distance d1, the distance d2 between the side surface of the cargo A and the reference line is measured again as shown in FIG. 3 (b). For reference, the figure shown by the broken line in the figure shows the plane position of the cargo A at the time of measuring the distance d1. The method of giving the distance a, that is, the interval between the first measurement of the distance d1 and the second measurement of the distance d2 may actually be a fixed time, or a constant rotation angle of the rotary encoder 2 may be used as a reference. Good. In this way, given the three dimensions a, d1, and d2, the inclination angle θ can be easily set as tan θ = (d2-d1) / a = b / a due to the geometrical relationship shown in FIG. 3 (c). Required to.

The inclination angle θ thus obtained is an intersection angle between the longitudinal direction of the drive roller 1 and the front surface of the rectangular parallelepiped cargo A, which is perpendicular to the traveling direction, as shown in FIG.

Using the auxiliary lengths L1 and L2 entered in FIG. 4, the relationship between the true length L, the apparent length L ', the true width D, the apparent width D', and the inclination angle θ is shown. Is organized as follows. D = D 'cos θ (1) L = L1 / cos co = (L'-L2) cos θ = L' / cos θ-D 'sin θ (2)

Since tan θ has been obtained from the beginning, if tan θ ≡t is set in consideration of the convenience of correction calculation, sin θ = t / (1 + t ² ) ^1/2 cos θ = 1 / (1 + t ² ) ^1/2 Since it can be expressed, equations (1) and (2) can be transformed into the following (3),
It can be rewritten as in equation (4). D = D '/ (1 + t 2) 1/2 ··· (3) L = L' / (1 + t 2) 1/2 -D't / (1 + t 2) 1/2 ··· (4)

Whichever of the equations (1) to (4) is used, the apparent lengths L'and D'are corrected by the inclination angle θ to obtain the true length L and width D by θ or tan θ. The required calculation is very easy to obtain.

The measurement in the above-mentioned embodiment has been described by taking as an example the method of obtaining the true length and width when the cargo A is inclining and advancing, but the gist of the present invention is the measurement procedure. Instead, the measurement may be performed using a transparent plate, and for example, the shape of the cargo may be recognized using a two-dimensional position measuring device.

[0021]

As described above, in the dimension measuring method according to the present invention, since the cargo is placed on the transparent plate which is sufficiently larger than the cargo and is carried on the conveyor rollers, the cargo falls between the rollers. Accurate measurement can be achieved.

[Brief description of drawings]

FIG. 1 is a perspective view of an embodiment.

FIG. 2 is an explanatory diagram in which a light beam is projected from an upper projector to a lower light receiver.

FIG. 3 is an explanatory diagram of a procedure for calculating a tilt angle θ.

FIG. 4 is a principle diagram of dimension correction.

FIG. 5 is an explanatory diagram when a cargo is long.

FIG. 6 is an explanatory diagram when the length of the cargo is short.

[Explanation of symbols]

 1 Drive Roller 2 Rotary Encoder 3a, 3b Photoelectric Element 4a, 4b Emitter / Receiver 5 Transparent Plate A Cargo

Claims (1)

[Claims] 1. When measuring the shape of a cargo being transported on a roller of a conveyor, the cargo is transported on the roller by placing it on a transparent plate which is sufficiently larger than at least the traveling direction of the cargo. A dimension measuring method characterized in that the shape of the cargo is optically measured using projection light in the vertical direction of the cargo passing through the transparent plate.