JPH11241917A - Method and apparatus for detecting plate shape - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely detect the plate shape all the time by arranging the oriented radiation main axis of emitted light rays of respective LED employed for a back light toward approximately to a camera means. SOLUTION: Together with a LED substrate 11, a LED light source is split into a plurality of groups and at the same time the remoter from the optical axis 6a of a camera, the more the divided substrate 11 comprising these LED groups are tilted to keep normals of the substrates approximately facing to the camera 6. In such a manner, the oriented radiation main axes of respectively emitted light rays of plural LEDs 12 of the respective groups are set toward the camera 6 and the emitted light rays from the LED light source are converged on the camera 6. Consequently, regardless of the width of a steel strip 2, the steel strip 2 is illuminated with approximately even intensity in the width direction, so that an image of the steel strip with high resolution can be obtained by the camera 6 without decreasing the quantity of light and the plate shape such as the width and the crop shape of the steel strip 2 can precisely be detected constantly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for illuminating a board using a plurality of LEDs as a backlight, capturing an image of the board, and detecting the board shape.

[0002]

2. Description of the Related Art For example, in a hot strip mill in an iron mill, a strip width meter or a crop shape meter is used as a steel strip shape detecting device. FIG. 4 shows a facility configuration of a crop profile meter in the hot strip mill. This equipment removes the leading end and the trailing end of a roughly rolled steel strip 2 conveyed along a pass line 1 in a direction indicated by an arrow A at a predetermined position by a crop shear 4 on the entry side of a finishing mill 3. It is a device for cutting. That is, in this apparatus, an LED light source 5 is disposed below the pass line 1 in front of the crop shear 4, and a one-dimensional solid-state image sensor (for example, a CCD) camera 6 is disposed above the L-axis.
The steel strip 2 is illuminated in the width direction by the ED light source 5, an image in the width direction of the steel strip 2 is captured by the camera 6, and the video signal is supplied to the crop shape meter 7 to output the crop shape of the steel strip 2. Is detected, a cutting position is determined from the shape, and a cutting signal corresponding to the cutting position is transmitted to the crop shear driving device 9 at a predetermined timing based on an output signal from the measuring roll 8, The end of the steel strip 2 is cut at a predetermined position. The detection signal of the steel strip 2 from the crop shape meter 7 is transmitted to a higher-level control device for tracking.

Here, as shown in FIG. 5, a plurality of LED light sources 5 are generally provided on an LED substrate 11 extending along the width direction of the pass line 1 as shown in FIG. (Light emitting diodes) 12 are arranged in a straight line. Note that, similarly to FIG. 5, in a width meter of a hot strip mill, an LED in which a plurality of LEDs are linearly arranged in the width direction below a pass line.
A light source is arranged, a one-dimensional solid-state imaging device camera is arranged above, an image in the width direction of the steel strip is taken, and the board width is measured from the number of pixels of the image.

[0004]

As shown in FIG. 6, the LED 12 includes a base 12b for holding an LED chip (not shown) and a lead 12a, and a base 1b.
Cap 12c provided on 2b to cover the LED chip
And light emitted through the cap 12c has directivity as indicated by reference numerals L1 and L2, for example.
The direction of the radiation main axis having the highest intensity is the normal direction of the base 12b passing through the center of the cap 12c.

However, in the above-described conventional shape detection device, as shown in FIG. 5, each of the plurality of LEDs 12 is arranged such that the main radiation axis thereof is directed vertically upward. For this reason, the intensity of the light incident on the camera 6 is lower than that of the camera 6, that is, L, located on the optical axis 6 a of the camera 6.
The ED is highest and becomes weaker as the distance from the optical axis 6a increases. For example, as shown in FIG. 7, when the length of the LED light source 5 is 3 m and the camera 6 is arranged at a position 5 m above the center thereof, the LEDs 1 at both ends of the LED light source 5
The angle formed between the main radiation axis 2 and the direction from the LED 12 toward the camera 6 is 16.7 °. In this case, LE
Assuming that D12 has the directivity indicated by reference numeral L1 in FIG. 6, the intensity of light traveling from the LEDs 12 at both ends toward the camera 6 is approximately 0.4 times the light intensity of the LED on the optical axis 6a. For this reason, there is a problem that the light amount at the width direction end of the steel strip 2 is reduced, and the shape of the steel strip 2 cannot be accurately detected.

In order to solve such a problem, the present inventor has proposed that the LED light source 5 be mounted on the LED substrate 11 as shown in FIG.
And a plurality of groups, and the substrates 11 of the LED groups on both sides thereof were developed so as to be inclined so that the normal line thereof faces the camera 6. However, as a result of various experimental studies,
In such a configuration, when the steel strip has a width enough to be illuminated by the light from the LED groups on both sides, the shape can be accurately detected, but the illumination light from the LED groups on both sides is not incident. It has been found that shapes such as a steel strip having a small width and a fish tail formed at the end in the transport direction cannot be detected accurately.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has as its object to provide a plate shape detecting method and apparatus which can always accurately detect various plate shapes.

[0008]

In order to achieve the above object, a plate shape detecting method according to the present invention comprises a plurality of LEDs.
Each LED so that the emitted light from
Are arranged with the radiation principal axis of the radiated light directed substantially toward the image pickup means, illuminate the plate with the plurality of LEDs as a backlight, and take an image of the image by the image pickup means to form the plate. Is detected.

Further, according to the present invention, an image pickup means is arranged on one side of a plate, a plurality of LEDs are arranged on the other side, and the plate is illuminated by the plurality of LEDs, and an image thereof is taken by the image pickup means In the plate shape detection device configured to detect the shape of the plate by imaging in the above, each of the LEDs is arranged so that the radiation main axis of the directivity of the radiated light is substantially directed to the imaging unit, and The structure is such that the light emitted from the LED is concentrated on the imaging means.

Further, according to the present invention, a plate conveyed along a predetermined pass line is illuminated by a plurality of LEDs arranged so as to extend from one side of the pass line in a direction orthogonal to the pass line. In a plate-shaped detection device configured to capture an image of the image by an imaging unit having a one-dimensional solid-state imaging device arranged on the other side of the pass line and detect the shape of the plate, the plurality of LEDs are It is divided into a plurality of groups, each is provided on the LED substrate, and the L
The ED substrate is arranged so that a normal line thereof is substantially directed to the image pickup means, so that light emitted from a plurality of LEDs in each group is concentrated on the image pickup means.

[0011]

FIG. 1 shows an embodiment of an apparatus for implementing a plate shape detecting method according to the present invention.
This plate shape detection device includes an LED light source 5 having a plurality of LEDs 12 arranged below the pass line 1 along the width direction thereof, and an LED light source 5 arranged above the pass line 1 as described with reference to FIGS. And a one-dimensional solid-state imaging device camera 6 having the LED light source 5 as a backlight and a pass line 1.
Is illuminated along the width direction of the steel strip 2 conveyed along, and the image thereof is captured by the camera 6 to detect the plate shape.

In this embodiment, in such a plate shape detecting device, the LED light source 5 is divided into a plurality of groups together with the LED substrates 11, and the substrates 11 of these LED groups are
The camera 6 is disposed so as to be tilted away from the optical axis 6 a so that each normal line thereof is substantially directed to the camera 6. In this way, the radiation main axis of the directivity of the emitted light of each of the plurality of LEDs 12 of each group is directed substantially toward the camera 6, and the emitted light from the LED light source 5 is concentrated on the camera 6.

Therefore, for example, as in FIG.
When the length of the D light source 5 is 3 m and the camera 6 is arranged at a position 5 m above the center, the LED light source 5
As shown in FIG. 2, the substrates of the LED groups on both sides are arranged at an angle of 16.7 ° toward the camera 6. The angle θ between the normal line at the substrate center of each LED group and the direction from the center toward the camera 6 is preferably −2 °.
≦ θ ≦ + 2 °.

According to this structure, the steel strip 2 can be illuminated with substantially uniform intensity in the width direction regardless of the width of the steel strip 2. It can be imaged at the resolution, steel strip 2
The shape of the plate such as the width of the image and the shape of the crop can always be detected accurately.

FIG. 3 is a diagram for comparing and explaining a specific arrangement example of the LED light source 5 according to the present invention and a conventional configuration. Here, the camera 6 is disposed at a position 5364 mm away from the center of the LED light source 5, and 14 LED groups are disposed on both sides of the optical axis 6a. The length of the substrate 11 of each LED group is 100 mm, and a plurality of LEDs are mounted on each substrate 11.
Since the LED groups on both sides are symmetric about the optical axis 6a, the arrangement of the LED groups on one side will be described here.

Here, from the optical axis 6a to the outside, the successive LED groups are referred to as a first LED group, a second LED group,..., And a fourteenth LED group.
1 are all horizontal as in the prior art, that is, the inclination angle Y is Y =
When arranged at 0 °, a normal line at the center of each substrate 11 and
The angle between the center and the direction toward the camera 6 is the first angle.
The LED group has the smallest angle of 0.5 °, and its angle increases as the LED group moves away from the optical axis 6a.
In the D group, the angle is 14.1 °, and as the distance from the optical axis 6a increases, the intensity of light traveling from each LED toward the camera 6 decreases.

In one specific arrangement example of the present invention, the first LE
The D group is Y = 0 °, the second to fourth LED groups are Y = 2.9 °, the fifth to seventh LED groups are Y = 5.7 °, and the eighth and ninth LED groups are Y.
= 8.6 °, the 10th to 12th LED groups have Y = 11.5 °,
In the thirteenth and fourteenth LED groups, each substrate 11 is arranged at an angle of Y = 14.5 °. With this arrangement, each substrate 11
The angle between the normal at the center of the lens and the direction from the center toward the camera 6 is the smallest at 0.2 ° in the third and sixth LED groups, and is −1.5 ° at the maximum in the tenth LED group,
All of the LED groups fall within the range of ± 2 °. Therefore, the intensity of light incident on the camera 6 from the center and the end of the LED light source 5 becomes substantially equal,
The plate shape can be accurately detected.

It should be noted that the present invention is not limited to only the above-described embodiment, and that various changes and modifications are possible. For example, the present invention is not limited to the one using a one-dimensional LED light source and a one-dimensional solid-state imaging device camera, such as a plate width meter and a crop shape meter in the above-described hot strip mill. The present invention can also be effectively applied to a case where a plate shape is detected using an image sensor camera. Further, the plurality of LEDs are not limited to being divided into a plurality of groups and inclining for each LED group, and may be arranged one-dimensionally in an arc shape centering on the imaging means or two-dimensionally in a spherical shape. Can also. Furthermore, by applying a part of the present invention to an LED display panel or the like, the emission principal axis of each LED can be concentrated at a predetermined observation position, so that the visibility can be improved.

[0019]

According to the present invention, the LEDs are arranged so that the radiation main axis of the directivity thereof is substantially directed to the image pickup means so that the light emitted from the plurality of LEDs is concentrated on the image pickup means. Since the plate is illuminated with the LED as a backlight, the image is taken by the image pickup means and the plate shape is detected, so that a uniform light amount can be secured in the image pickup means. Therefore, for example, in a plate width meter and a crop shape meter in a hot strip mill, various plate shapes can always be accurately detected without a decrease in light amount.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a view for explaining the embodiment shown in FIG. 1;

FIG. 3 is a diagram for comparing and explaining a specific arrangement example of an LED light source according to the present invention and a conventional example.

FIG. 4 is a diagram showing a facility configuration of a crop shape meter in a hot strip mill.

FIG. 5 is a view of the LED light source shown in FIG.

FIG. 6 is a diagram showing a configuration and directivity of an LED.

FIG. 7 is a diagram illustrating a problem in a conventional LED light source.

FIG. 8 is a diagram showing a configuration of a shape detection device developed earlier by the present inventors.

[Explanation of symbols]

 Reference Signs List 1 pass line 2 steel strip 5 LED light source 6 one-dimensional solid-state imaging device camera 6a optical axis 11 LED substrate 12 LED

Claims (3)

[Claims] An LED is arranged such that radiation main axes of directivity of the emitted light are substantially directed to the image pickup means so that light emitted from the plurality of LEDs is concentrated on the image pickup means. A plate shape detection method, wherein a plate is illuminated as a backlight, and an image of the plate is taken by the imaging means to detect the shape of the plate. 2. An image pickup means is arranged on one side of a plate, and a plurality of LEDs are arranged on the other side.
A plate-shaped detection device configured to illuminate with an ED and detect an image of the plate by detecting the shape of the plate by capturing the image with the imaging unit. The plurality of LEDs
A plate-shaped detection device, characterized in that light emitted from the device is concentrated on the imaging means. 3. A plate conveyed along a predetermined pass line is illuminated from one side of the pass line by a plurality of LEDs arranged so as to extend in a direction perpendicular to the pass line. In a plate-shaped detection device configured to detect the shape of the plate by capturing an image with an imaging unit having a one-dimensional solid-state image sensor arranged on the other side of the pass line, the plurality of LEDs are divided into a plurality of groups. Divide and LE
In addition to being provided on the D board, the LED boards of each group were arranged so that the normal line thereof was substantially directed to the image pickup means, so that light emitted from the plurality of LEDs of each group was concentrated on the image pickup means. A plate shape detection device, characterized in that: