JP2007333589A - Tire inspection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tire inspection method capable of correcting the brightness output of a background so as to make it uniform regardless of the distance between an electromagnetic radiation source and a camera. <P>SOLUTION: An X-ray camera is irradiated with X rays by an X-ray source 1 and an approximate function calculated from the relation between the distance between the X-ray source and the camera element just under it and the energy of the camera element while the radiation voltage of the X-ray source 1 is calculated from the approximate function. Thereafter, the radiation voltage of the X-ray source 1 is adjusted corresponding to the distance between the X-ray source 1 and the camera element to set the brightness output of the camera element to a predetermined value. Subsequently, the brightness output of the camera element present just under the X-ray source 1 and the brightness output of another camera element spaced apart the camera element are calculated and the brightness output of an another camera element is corrected by multiplying the cube of the straight line distance between the X-ray source 1 and the camera element by the cube the straight line distance between the X-ray source 1 and another camera element. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention acquires an image of the inside of a tire arranged between an electromagnetic radiation source and a camera composed of a plurality of camera elements facing the source, and a belt cord (steel cord) inside the tire based on the acquired image. ) Related to a tire inspection method for inspecting the arrangement.

Conventionally, when performing a tire inspection, an image is acquired by imaging a tire with a camera using electromagnetic radiation such as X-rays or γ-rays, and the inside of the tire is observed based on the acquired image (for example, patents). Reference 1).
JP-A-6-341930

  In conventional tire inspection, the output is constant even if the distance between the electromagnetic radiation source and the camera changes according to the tire size, so the luminance output of the camera element directly under the electromagnetic radiation source is the electromagnetic radiation. There is a disadvantage that the distance varies depending on the distance between the source and the camera, that is, the size of the tire. In addition, since the camera output changes in the width direction of the camera, a uniform background luminance output cannot be obtained, density unevenness in the image, and it is difficult to obtain an image with high contrast / brightness.

  Furthermore, the correction of the luminance output of the camera, that is, the background, uses the correction value obtained by adjusting the gain at the time of starting up the apparatus for all shootings, that is, depends only on experimental data, so that the shooting conditions It is necessary to take data every time. Therefore, the correction takes time and cannot follow the output change accompanying the temperature change or the like, and it is difficult to obtain the corrected data with reliability.

  An object of the present invention is to provide a tire inspection method capable of correcting a background luminance output to be uniform regardless of a distance between an electromagnetic radiation source and a camera.

The tire inspection method according to the present invention includes:
A tire for acquiring an image inside a tire arranged between an electromagnetic radiation source and a camera composed of a plurality of camera elements opposed thereto, and inspecting the arrangement of a belt cord inside the tire based on the obtained image An inspection method,
The electromagnetic radiation source irradiates the camera with electromagnetic waves;
The first energy and the second energy of the camera element when the distance between the electromagnetic radiation source and the camera element immediately below the electromagnetic radiation source is a first distance, a second distance, and a third distance. And measuring each of the third energy;
Obtaining an approximate function from the first distance and the first energy, the second distance and the second energy, and the third distance and the third energy;
Calculating a radiation voltage of the electromagnetic radiation source from the approximate function;
Adjusting the radiation voltage of the electromagnetic radiation source according to the distance between the electromagnetic radiation source and the camera element, and setting the luminance output of the camera element to a predetermined value;
Obtaining a luminance output of a camera element directly below the electromagnetic radiation source, and a luminance output of another camera element spaced from the camera element;
The luminance output of the other camera element is a ratio of the cube of the linear distance between the electromagnetic radiation source and the other camera element to the cube of the linear distance between the electromagnetic radiation source and the camera element. And a step of correcting by multiplication.

  According to the tire inspection method of the present invention, the electromagnetic radiation source irradiates the camera with electromagnetic waves, and the first distance, the second distance, and the second distance are between the electromagnetic radiation source and the camera element immediately below the electromagnetic radiation source. The first energy, the second energy, and the third energy of the camera element when the distance is 3 are measured. Thereafter, an approximate function is obtained from the first distance and the first energy, the second distance and the second energy, and the third distance and the third energy, and the radiation voltage of the electromagnetic radiation source is calculated from the approximate function. . Thereafter, the radiation voltage of the electromagnetic radiation source is adjusted according to the distance between the electromagnetic radiation source and the camera element, and the luminance output of the camera element is set to a predetermined value. Thereby, the luminance output of the camera element directly under the electromagnetic radiation source can be set to a predetermined value regardless of the distance between the electromagnetic radiation source and the camera element.

  Thereafter, the luminance output of the camera element directly under the electromagnetic radiation source and the luminance output of another camera element separated from the camera element are obtained, and the luminance output of the other camera element is calculated between the electromagnetic radiation source and the camera element. Correction is made by multiplying the ratio of the cube of the linear distance between the electromagnetic radiation source and the other camera element to the cube of the linear distance between.

  The distance between the electromagnetic radiation source and the other camera element changes depending on the position of the other camera element in the camera, and the electromagnetic radiation is attenuated by the square of the distance. It may be appropriate to multiply the ratio of the square of the linear distance between the electromagnetic radiation source and the other camera element to the square of the linear distance between.

  However, since the energy of electromagnetic radiation irradiated to the camera element and other camera elements must be compared in the same area, it is necessary to consider the angle formed between the electromagnetic radiation source, the other camera elements, and the camera element. . As a result, the other cameras are actually multiplied by the ratio of the cube of the linear distance between the electromagnetic radiation source and the other camera element to the cube of the linear distance between the electromagnetic radiation source and the camera element. It is appropriate to correct the luminance output of the element.

  In this way, the luminance output of the camera element immediately below the electromagnetic radiation source is set to a predetermined value regardless of the distance between the electromagnetic radiation source and the camera element, and the straight line between the electromagnetic radiation source and the camera element is set. By multiplying the ratio of the cube of the linear distance between the electromagnetic radiation source and other camera elements to the cube of the distance and correcting the luminance output over the entire camera element of the camera, the electromagnetic radiation source and the camera The luminance output of the background can be corrected so as to be uniform regardless of the distance between the two.

An embodiment of a tire inspection method according to the present invention will be described in detail with reference to the drawings.
FIG. 1 is a view showing a tire inspection apparatus for carrying out a tire inspection method according to the present invention. The tire inspection apparatus includes an X-ray source 1, an X-ray camera 2 having a plurality of camera elements arranged in a matrix, an image processing unit 3, and a monitor 4.

  The X-ray source 1 is movable in the y-axis direction (vertical direction) of the three-dimensional coordinate system, and irradiates the tire 5 to be inspected with X-rays. The X-ray camera 2 receives X-rays that have passed through the tire 5 and acquires an image of the inspection target portion of the tire 5. The image processing unit 3 performs processing steps described later on the acquired image, outputs the processed image to the monitor 4, and is controlled by a control unit described later.

  The operation of this embodiment will be described. The operation is roughly divided into adjustment of the luminance output of the camera element directly below the X-ray source 1 and correction of the luminance output of the entire camera element of the X-ray camera 3. The adjustment of the luminance output of the camera element immediately below the X-ray source 1 will be described. First, the X-ray source 1 irradiates the X-ray camera 2 with X-rays, and the X-ray source 1 and the X-ray source 1 immediately below. The image processing unit 3 measures the energy b1, b2, b3 of the camera element when the distance between the camera element at the position X0 is the distance a1, a2, a3. Next, the image processing unit 3 obtains an approximate function as shown in FIG. 2 from the distance a1 and the energy b1, the distance a2 and the energy b2, and the distance a3 and the energy b3, and the actually used range of the obtained approximate functions. The radiation voltage of the X-ray source 1 is calculated from

  Next, the radiation voltage of the X-ray source 1 is adjusted according to the distance between the X-ray source and the camera element at the position X0, and the luminance output of the camera element at the position X0 is set to a target value. That is, as shown in FIG. 3, the luminance output is increased when the luminance output is lower than the target value A as shown by the curve α1, and the luminance output is increased when the luminance output is higher than the target value A as shown by the curve α2. Decrease and set the luminance output to the target value as shown by the curve α3. Thereby, the luminance output of the camera element at position X0 can be set to the target value regardless of the distance between the X-ray source 1 and the camera element at position X0. In FIG. 3, the horizontal axis represents the position of the camera element in the horizontal direction, and the vertical direction represents the luminance output of the camera element.

  The correction of the luminance output of the entire camera element of the X-ray camera 2 will be described with reference to FIG. First, the luminance output Ea of the camera element 2a at the position X0 immediately below the X-ray source 1 and the luminance output Eb ′ of the other camera element 2b spaced from the camera element 2a are obtained, and the luminance output Eb ′ of the camera element 2b is obtained. Is multiplied by the ratio of the cube of the linear distance b between the X-ray source 1 and the camera element 2b to the cube of the linear distance a between the X-ray source 1 and the camera element 2a.

Since the distance between the X-ray source 1 and the camera element 2b changes according to the position of the camera element 2b in the camera 2, that is, the distance from the camera element 2a, and the X-ray attenuates by the square of the distance, It may be appropriate to multiply by the ratio of the square of the linear distance b to the square of the distance a. That is, it is considered that a relationship of Ea = Eb × b ² / a ² is established between the luminance output Ea of the camera element 2a and the luminance output Eb of the camera element 2b.

However, the energy of the X-rays irradiated to the camera elements 2a and 2b must be compared in the same area, and the actual luminance output of the camera element 2b is Eb ′ smaller than Eb in FIG. It is also necessary to consider the angle θ formed by the radiation source 1, the camera element 2b and the camera element 2a. That is, the relationship of Ea = Eb ′ × 1 / sin θ × b ² / a ² = Eb ′ × b ³ / a ³ exists between the luminance output Ea of the camera element 2a and the luminance output Eb ′ of the camera element 2b. To establish. As a result, in practice, the ratio of the cube of the linear distance b between the X-ray source 1 and the camera element 2b to the cube of the linear distance a between the X-ray source 1 and the camera element 2a is multiplied. Thus, it is appropriate to correct the luminance output of the camera element 2b.

  FIG. 5 is a graph showing changes before and after correction of the luminance output distribution of the camera element. In FIG. 5, the horizontal axis represents the position of the camera element in the horizontal direction, and the vertical direction represents the luminance output of the camera element. The luminance output distribution of the camera element obtained when the X-ray source 1 irradiates the camera 2 with X-rays is as shown by a curve β1, and the luminance output of the camera element 2a at the position X0 directly below the X-ray source 1 is targeted. By setting the value A, the luminance output distribution of the camera element becomes as shown by the curve β2.

When the luminance output of the camera element separated from the position X0 is corrected according to the relationship of Ea = Eb × b ² / a ² , the luminance output distribution as shown by the curve β3 is obtained, and the luminance output over the whole is within 5% of the target value. It can be seen that it does not fit in. On the other hand, when the luminance output of the camera element separated from the position X0 is corrected according to the relationship of Ea = Eb × b ³ / a ³ , the luminance output distribution as shown by the curve β4 is obtained, and the luminance output over the whole is the target value. It can be seen that it is within 5%.

  FIG. 6A is a diagram showing an image inside the tire acquired before correction by the tire inspection method according to the present invention, and FIG. 6B shows an image inside the tire acquired after correction by the tire inspection method according to the present invention. FIG. Before correction, as shown in FIG. 6A, the entire image is dark and the contrast is low, so the structure of the belt portion inside the tire cannot be seen well. On the other hand, after correction, as shown in FIG. 6B, the entire image is moderately bright and the contrast is high, so that the structure of the belt portion inside the tire can be seen well.

  In this way, the luminance output of the camera element 2a immediately below the X-ray source 1 is set to the target value regardless of the distance between the X-ray source 1 and the camera element 2a, and the X-ray source 1 and the camera element 2a are set. Is multiplied by the ratio of the cube of the linear distance b between the X-ray source 1 and the camera element 2b to the cube of the linear distance a between the camera 2 and the luminance output over the entire camera element of the camera 2 is corrected. Thus, the background luminance output can be corrected to be uniform regardless of the distance between the X-ray source 1 and the camera 2.

  Here, image correction in the tire inspection method according to the present invention will be described. When the control unit 6 having a control mechanism such as correction is attached to the X-ray camera 2 (see FIG. 7A), the correction processing is acquired from the X-ray camera 2 by instructing the control unit 6 from the image processing unit 3 The corrected image is corrected.

  When the X-ray camera 2 does not include the control unit 6, the image transmitted from the X-ray camera 2 is corrected by the image processing unit 3 (see FIG. 7B), or the X-ray camera 2 and the image processing unit. The control unit 6 is arranged between the image processing unit 3 and the image transmitted from the X-ray camera 2 to the image processing unit 3 is corrected according to support from the image processing unit 3 (see FIG. 7C).

The present invention is not limited to the above-described embodiment, and many changes and modifications can be made.
For example, in the above embodiment, X-rays are used as the electromagnetic radiation source, but other electromagnetic radiations such as γ rays can be used.

It is a figure which shows the tire inspection apparatus which enforces the tire inspection method by this invention. It is a figure which shows the approximation function calculated | required with the tire inspection method by this invention. It is a figure for demonstrating adjustment of the luminance output of the camera element located right under X-ray source. It is a figure for demonstrating correction | amendment of the luminance output of a camera element. It is a graph which shows the change before and behind correction | amendment of the luminance output distribution of a camera element. FIG. 6A is a diagram showing an image inside the tire acquired before correction by the tire inspection method according to the present invention, and FIG. 6B shows an image inside the tire acquired after correction by the tire inspection method according to the present invention. FIG. It is a figure for demonstrating correction | amendment of the image in the tire inspection method by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 X-ray source 2 X-ray camera 2a, 2b Camera element 3 Image processing part 4 Monitor 5 Tire 6 Control part

Claims (1)

A tire that acquires an image of the inside of a tire arranged between an electromagnetic radiation source and a camera composed of a plurality of camera elements facing the source, and inspects the arrangement of the belt cord inside the tire based on the acquired image An inspection method,
The electromagnetic radiation source irradiates the camera with electromagnetic waves;
The first energy and the second energy of the camera element when the distance between the electromagnetic radiation source and the camera element immediately below the electromagnetic radiation source is a first distance, a second distance, and a third distance. And measuring each of the third energy;
Obtaining an approximate function from the first distance and the first energy, the second distance and the second energy, and the third distance and the third energy;
Calculating a radiation voltage of the electromagnetic radiation source from the approximate function;
Adjusting the radiation voltage of the electromagnetic radiation source according to the distance between the electromagnetic radiation source and the camera element, and setting the luminance output of the camera element to a predetermined value;
Obtaining a luminance output of a camera element directly below the electromagnetic radiation source, and a luminance output of another camera element spaced from the camera element;
The luminance output of the other camera element is a ratio of the cube of the linear distance between the electromagnetic radiation source and the other camera element to the cube of the linear distance between the electromagnetic radiation source and the camera element. A tire inspection method comprising: a step of correcting by multiplication.

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