WO2023074867A1 - Method for measuring rotational-direction main groove depth of tire, and device for measuring-rotational direction main groove depth using method - Google Patents

Method for measuring rotational-direction main groove depth of tire, and device for measuring-rotational direction main groove depth using method Download PDF

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Publication number
WO2023074867A1
WO2023074867A1 PCT/JP2022/040471 JP2022040471W WO2023074867A1 WO 2023074867 A1 WO2023074867 A1 WO 2023074867A1 JP 2022040471 W JP2022040471 W JP 2022040471W WO 2023074867 A1 WO2023074867 A1 WO 2023074867A1
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depth
light
tire
coordinates
main groove
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PCT/JP2022/040471
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French (fr)
Japanese (ja)
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田中文敏
勝村和重
風間正利
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中央海産株式会社
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Priority to PCT/JP2023/016781 priority Critical patent/WO2024089917A1/en
Publication of WO2023074867A1 publication Critical patent/WO2023074867A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/22—Measuring arrangements characterised by the use of optical techniques for measuring depth
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
    • G01B11/25—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures by projecting a pattern, e.g. one or more lines, moiré fringes on the object

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  • the present invention relates to the measurement of the depth of the main groove in the rotational direction formed on the tread surface of a tire such as an automobile or motorcycle.
  • the present invention relates to a method for measuring the depth of the main groove in the rotational direction of a tire based on the captured image, and a measuring apparatus using the method.
  • Tires of vehicles such as automobiles if worn beyond a certain level, may break while the vehicle is running and cause a serious accident, so it is necessary to replace them with new tires at an appropriate time. It has become.
  • Tire life depends not only on the mileage of the vehicle, but also on individual factors such as the type of vehicle, the condition of the road surface on which the tire is constantly driven, and the habits of the driver. It is not appropriate to make a judgment based on the number of tires, but it is important to investigate the wear condition of each tire and make a judgment.
  • the main factors that govern the life of tires are the wear of the tread surface and the occurrence of scratches such as cracks and cuts.
  • the progress of wear on the tread surface is often judged from the depth of the tire groove. That is, longitudinal grooves (circumferential grooves) and lateral grooves are formed on the tread surface in the direction of rotation of the tire in order to release water trapped between the road surface and the tire to the rear or side of the tire.
  • a laser displacement meter is often used as means for three-dimensionally measuring the shape of the surface of an object.
  • a laser displacement gauge measures the remaining groove depth of a tire.
  • Patent Document 1 while rotating the tire around its rotation axis, the tread surface of the tire is irradiated with incident light from a predetermined direction, and the reflected light at a predetermined angle with respect to the incident light is received by a light receiving portion. and acquires tire tread depth data.
  • the measurement of the residual groove depth by the laser displacement gauge has the following problems.
  • a fan-shaped light beam is created by a laser or a shadowed light-emitting diode as a light source for irradiating transversely to the direction of travel of the tire. Since the measurements are made non-orthogonal to the surface of the tire, neither the light source nor the sensor are located at the angular direction of direct reflection.
  • the sensor is in this case a two-dimensional image analysis camera. The evaluation is done by generating a measured tire tread envelope and looking for the deepest points of the tread grooves.
  • the deepest part of the tread groove is determined as the remaining groove depth of the tire by the light section method.
  • longitudinal grooves (circumferential grooves) and lateral grooves are formed on the tread surface of the tire in the direction of rotation of the tire, it is determined whether the determined grooves are longitudinal grooves (circumferential grooves) or lateral grooves. I can't.
  • a tire in use may have various irregularities. Therefore, there is a problem that a groove determined to be a circumferential groove may not actually be a circumferential groove.
  • Patent Document 3 captures an image of line light (image of a light-section line) irradiated on the surface of a relatively moving object to be measured (surface of a rotating tire, etc.), and light-section based on the captured image.
  • a shape measuring apparatus and method for detecting the surface shape of an object to be measured by performing shape detection using a method is disclosed.
  • Patent Document 3 irradiates the surface of the object to be measured with a plurality of line lights from a direction different from the detection height direction of the surface of the object to be measured.
  • line light irradiation means for forming a plurality of separated light-section lines extending in a second direction orthogonal to one direction and having mutually displaced ranges in the second direction; and a plurality of lines formed on the surface of the object to be measured.
  • an imaging means for imaging an image of the separated light-section line in the direction in which the principal ray of each of the plurality of line lights is specularly reflected on the surface of the object to be measured; For each of the plurality of captured images obtained, light sectioning is performed from each of the images of the plurality of independent image processing target regions preset corresponding to the plurality of separated light section lines in the coordinate system of the captured image of the imaging means.
  • light-section line coordinate detecting means for individually detecting light-section line coordinates that are coordinates of the line image; and a first direction of the object to be measured based on the plurality of light-section line coordinates detected by the light-section line coordinate detection means and surface shape calculating means for calculating the surface height distribution in the shape measuring apparatus.
  • the shape measuring device disclosed in Patent Document 3 below measures the shape of the side surface of the tire and the shape of the tread surface of the tire while rotating the tire, thereby determining the shape of the entire tire. It is what you measure. For this reason, in this technology, a plurality of separated line lights are irradiated onto the tread surface of the tire, and the coordinates of the images of the line lights are detected by the light-section line coordinate detection means corresponding to each line light, so that the tire is rotating. Even if there is no delay in the processing.
  • JP-A-2016-161360 Japanese Patent No. 5640073 Japanese Patent No. 5089286
  • the present invention is a device for measuring the depth of the main groove (circumferential groove) in the direction of rotation of the tire formed on the tread surface of the tire removed from a vehicle such as an automobile or motorcycle, and the manufacturing cost of the device is To provide a device for measuring the depth of the main groove in the rotational direction of the tread surface of a tire which is low in cost and maintenance cost and which can be easily measured.
  • the first aspect of the present invention for solving the above problems is to irradiate the tread surface of the tire with a line laser beam in a direction transverse to the rotation direction of the tire, and capture an image of the line laser beam on the tread surface with a camera.
  • a method for measuring the depth of a main groove in the rotational direction, in which an image is captured and the depth of a plurality of main grooves in the rotational direction formed on the tread surface is detected by an optical section method based on the captured image, irradiating at least two different locations on the tread surface with a line laser beam, and capturing images of the line laser beam, respectively; Detecting light-section line coordinates, which are coordinates of the image of the line laser light, for each of the captured images, calculating groove depths formed on the tread surface based on the triangulation method from the light-section line coordinates, A depth of a main groove in the rotational direction formed on a tread surface of a tire, characterized in that a depth of the groove at which the coordinates in the
  • a second aspect of the present invention is a captured image obtained by irradiating the tread surface of a tire with a line laser beam in a direction transverse to the rotation direction of the tire, and capturing an image of the line laser beam on the tread surface with a camera.
  • a third aspect of the present invention is a line laser beam irradiation device for irradiating a line laser beam onto at least two different locations on the tread surface of the tire in a direction transverse to the rotational direction of the tire; a camera that captures an image of the line laser light on the tread surface; a line laser image detection unit that detects an image of line laser light from an image captured by the camera; a light-section line coordinate detection unit that detects light-section line coordinates that are coordinates of an image of the line laser light; a groove depth calculator that calculates the depth of the grooves formed on the tread surface from the light-section line coordinates based on the light-section method; a main groove determination unit configured to determine each of a plurality of grooves in which the coordinates of the calculated depth of the groove in the rotation direction substantially match each other as a rotation direction main groove.
  • line laser light is applied to at least two different locations on the tread surface of the tire, and an image of the line laser light on the tread surface of the tire is captured by a camera. An image of the line laser light is detected from each captured image, and light-section line coordinates, which are the coordinates of the image of the line laser light, are detected.
  • the depth of the groove can be calculated from the arrangement of the line laser light irradiation device and the camera, and the coordinates of the light-cutting line, based on the triangulation method using the principle of the light-cutting method.
  • a point A which is one coordinate of the light-section line coordinates, and a distance w away from the point A in a direction transverse to the tire rotation direction point B, which is one coordinate of the light-section line coordinates
  • point C which is one coordinate of the light-section line coordinates, which is separated from the point A by 2w in a direction transverse to the rotation direction of the tire.
  • the area of the triangle formed by the point A, the point B, and the point C is repeated until any one of the points A, B, and C becomes all the coordinates of the light-section line coordinates.
  • a groove depth is calculated from the quadratured area of the triangle, and groove depths having the groove depth equal to or greater than a predetermined value and having substantially the same coordinates in the rotation direction are determined as main rotation directions. Determine the depth of the groove.
  • the tread surface of the tire is a gently curved surface
  • the image of the line laser light picked up by the camera also has a gently curved surface. Therefore, when calculating the groove depth, it is necessary to calculate the groove depth in a direction perpendicular to the normal line of the light section line divided (separated) by the groove portion. For that purpose, 3 points are selected from the light-section line coordinates, the area of the triangle composed of the 3 points is quadratured for all the light-section line coordinates, and the maximum value of the groove depth obtained from there is calculated as the groove Depth is preferably determined.
  • point A which is one coordinate of light-section line coordinates
  • point B which is one coordinate of light-section line coordinates
  • point C which is one coordinate of the light-section line coordinates separated from point A by 2w in a direction transverse to the tire rotation direction.
  • a device for measuring the depth of the main groove (circumferential groove) in the direction of rotation of the tire formed on the tread surface of the tire removed from a vehicle such as an automobile or motorcycle It has become possible to provide a device for measuring the depth of the main groove in the rotational direction of the tread surface of a tire, which is low in maintenance cost and easy to measure.
  • the apparatus for measuring the depth of the rotational direction main groove formed on the tread surface of a tire according to the present invention is characterized by low equipment cost, easy maintenance, and simple measurement.
  • FIG. 1 is a perspective view showing the construction of a measuring apparatus 1 for measuring the depth of a main groove in the tread surface of a tire according to the first embodiment of the present invention.
  • This apparatus includes a table 50 on which a tire 40 is placed, a line laser light irradiation device 10, a camera 20 for capturing an image of the line laser light, and a data processing device 30 for analyzing and processing the image captured by the camera.
  • a light source that makes the tread surface of the tire 40 clear according to environmental conditions.
  • the tire 40 is placed on the table 50 so that the tire side surface is horizontal.
  • the line laser beam irradiation device 10 is arranged symmetrically with respect to the camera 20, and irradiates the tread surface of the tire 40 with line laser beams in a direction transverse to the rotation direction of the tire so as to irradiate two different points on the tread surface.
  • Forms an image of line laser light The camera 20 captures images of line laser light appearing at two different locations on the tread surface, and the captured images are sent to the data processing device 30 .
  • the purpose of the line laser light image is to obtain information on the remaining groove depth of the tire 40 . In the embodiment shown in FIG.
  • the camera 20 is arranged between the two line laser light irradiation devices 10, but the present invention is not limited to this, and is based on the principle of the light section method. It suffices if the arrangement (height, distance, angle, etc.) relationship between the camera 20, the line laser beam irradiation device 10, and the tread surface of the tire, which is necessary for the triangulation method used, can be specified.
  • the present invention when acquiring a line laser beam image of the tread surface in a direction transverse to the rotating direction of the tire, two different locations on the tread surface are irradiated with the line laser beam and captured by the camera 20. There is a feature in the place to do. This is because the tread surface is formed with lateral grooves and oblique grooves in addition to the main grooves in the direction of rotation, and the tread surface may become uneven due to use. The reason why the line laser light is applied to two different places on the tread surface is to distinguish between the main grooves in the rotational direction and the other grooves. Here, it is preferable to simultaneously irradiate two different locations on the tread surface with the line laser beam. You can go with that.
  • the characteristic that the rotational direction main grooves are always continuous in the rotational direction is used. That is, from the coordinates of the light cutting line 11 (see FIG. 3), which is the image of the line laser beam, the grooves whose coordinates in the rotation direction are substantially the same are determined as the main grooves in the rotation direction. It is a point. However, there are cases where the main grooves are formed in a meandering shape in the tire rotation direction, and there are cases where the main grooves are not necessarily continuous in the rotation direction due to the relationship with the lateral grooves. Even with such a main groove, from the coordinates of the light-section line 11, grooves whose coordinates in the rotational direction are substantially the same are determined as rotational direction main grooves.
  • FIG. 2 shows the height direction of the camera 20 of the measuring device 1 according to the embodiment of the present invention shown in FIG. It is a figure showing positional relationship.
  • the line laser beam irradiation devices 10 are arranged symmetrically in the rotation direction of the tire 40 with the camera 20 interposed therebetween.
  • the irradiation angle of the line laser beam irradiation device 10 is an angle for irradiating the center of the tire 40, which is the object to be measured.
  • the diameter of the tire to be measured varies, for example, the angle for irradiating the center of the tire with the smallest diameter is set.
  • the height of the camera 20 from the tread surface is set to a height at which images of two line laser beams can be acquired (a viewing angle can be secured), and the camera 20 is installed at the same height as that height.
  • D is the depth of the rotational direction main groove 41 of the tire 40
  • ⁇ is the incident angle of the line laser beam 100 onto the tread surface of the tire 40
  • w is the width of the main groove 41
  • D tan ⁇ w.
  • w is wider than the width of the main groove 41, and is preferably about 1 to 2 times the width of the main groove 41, for example. This is because the width of the main groove may change due to wear of the tire, and the main groove may be formed in a meandering shape in the tire rotation direction.
  • FIG. 3 is a diagram of a tire placed with its side surface horizontal, and a line laser beam emitted from the line laser beam irradiation device 10 to the tread surface of the tire 40 .
  • Line laser beams 100 are irradiated from two line laser beam irradiation devices 10 to two different locations on the tread surface, and two light cutting lines 11, which are images of the line laser beams, appear on the tread surface.
  • the image of the light cutting line 11 appears not as an image reflected from the tread surface but as an image reflected from the bottom surface of the main groove 41 at the location where the tire rotational direction main groove 41 is formed. That is, as shown in FIG. 2(b), the image of the light cutting line 11 of the main groove 41 of the light cutting line 11 is more sensitive to the depth of the main groove 41 than the image appearing on the tread surface. Appears on the irradiation direction side.
  • the characteristic that the main grooves in the rotational direction are continuous in the rotational direction is used as a discriminating means.
  • two line laser light images are generated on the tread surface, and the coordinates of the light cutting lines 11 (light cutting line 11-1, light cutting line 11-2) that are the images of the line laser light (light cutting line coordinates), grooves with matching coordinates in the direction of rotation are determined as main grooves in the direction of rotation.
  • FIG. 4 is a diagram showing an embodiment of the present invention in which the depth of the main groove in the rotational direction is calculated from the light cutting line 11, which is the image of the line laser light.
  • the tire groove gauge tire groove depth gauge
  • the groove depth is measured so that it hits the This is because the tread surface is a gently curved surface.
  • the depth of the main groove can be calculated by the triangulation method from the distance h between the line laser light image of the tread surface and the line laser light image of the main groove.
  • the distance between the light-section line coordinates of the tread surface and the light-section line coordinates of the main groove differs depending on how the coordinates are taken.
  • the coordinate axes shown in FIG. 4 represent the resolution of an image of the tread surface of 1000 ⁇ 1000 dots, that is, the coordinates of the X-axis are 0-1000 and the coordinates of the Y-axis are 0-1000.
  • a point B which is one coordinate of the light-section line 11
  • a point C which is one coordinate of the light-section line 11, which is separated from the point A by 2w in a direction transverse to the rotating direction of the tire are selected.
  • each groove depth is calculated. is 1.6 mm, and 0.8 mm for two-wheels) or more is determined as the depth of the main groove.
  • FIG. 5 is a block diagram showing the configuration of a measuring device 1 for measuring the depth of a main groove in the tread surface of a tire according to one embodiment of the present invention.
  • the two line laser beam irradiation devices 10 irradiate line laser beams to different locations on the tread surface of the tire.
  • a camera 20 captures an image of the line laser light appearing on the tread surface.
  • the line laser control section 310 of the control section 31 controls the line laser light irradiation device 10
  • the imaging control section 311 of the control section 31 controls the camera 20 .
  • the data processing unit 32 includes a line laser image detection unit 320 that detects an image of the line laser light, and a light cutting line that detects the coordinates of the line laser light image detected by the line laser image detection unit 320.
  • a main groove determination unit 323 for determining the rotational direction main groove.
  • FIG. 6 shows the depth of the main groove in the rotational direction of the tire (size: 215/55R17) obtained by measuring the depth of the main groove in the rotational direction formed on the tread surface of the tire according to one embodiment of the present invention. It is a diagram.
  • the line laser has a wavelength of 600 nm, a power consumption of 40 mW, a power supply voltage of 5 VD, and a resolution of the camera 20 of 2048 ⁇ 1536.
  • the image acquired with such specifications was processed, the coordinates of the light cutting line 11 were obtained, and the depth of the main groove in the rotational direction was calculated.
  • a depth of 5.9 mm was detected from
  • FIG. 7 is a flow chart showing an example of a method for measuring the depth of the main groove in the rotational direction according to one embodiment of the present invention.
  • linear interpolation is performed on pixels (defective points) that originally exist in the image of the line laser beam but have disappeared (S5, S6), and the coordinates of the light cutting line 11, which is the image of the line laser beam, are extracted (S7). ).
  • points A, B, and C are selected from the coordinates of each light-section line 11, and the area of a triangle formed by points A, B, and C is quadratured (S8, S9). This is repeated until the point A becomes the coordinate of all the light-section lines 11, the area of the triangle formed by the points A, B, and C is quadratured (S10), the area of the triangle is taken as the Y axis, The maximum value of the graph with the Y-axis coordinate of the light cutting line 11 as the X-axis is taken as a main groove candidate (S11).
  • the Y-coordinate of the light-section line 11 is substantially the same. If not, it is determined to be the main groove in the rotational direction. Then, the depth of the main groove is calculated from the area of the groove determined to be the main groove (S12, S13).
  • FIG. 1 is a perspective view showing the configuration of a tire rotation direction main groove depth measuring device formed on a tread surface of a tire according to an embodiment of the present invention
  • FIG. 1 is a view showing the positional relationship in the height direction between a camera, a line laser beam irradiation device, and a tread surface of a tire of a tire rotation direction main groove measuring device according to an embodiment of the present invention
  • FIG. 2 is an irradiation diagram of line laser light that is applied to the tread surface of a tire by a line laser irradiation device that is an embodiment of the present invention.
  • FIG. 1 is a perspective view showing the configuration of a tire rotation direction main groove depth measuring device formed on a tread surface of a tire according to an embodiment of the present invention
  • FIG. 1 is a view showing the positional relationship in the height direction between a camera, a line laser beam irradiation device, and a tread surface of a tire of a tire rotation direction main groove measuring device according to an embodiment of the present invention
  • FIG. 4 is a diagram showing an embodiment of the present invention in which the depth of the main groove in the rotational direction is calculated from the cutting line coordinates 11 that are the image of the line laser beam.
  • 1 is a block diagram showing the configuration of a measuring device 1 for measuring the depth of a main groove in the tread surface of a tire according to an embodiment of the present invention
  • FIG. FIG. 4 is a diagram of the depth of a rotational direction main groove obtained by a line laser irradiation device that is an embodiment of the present invention
  • 4 is a flow chart showing an example of a method for measuring the depth of the main groove in the rotational direction formed on the tread surface of the tire according to one embodiment of the present invention.
  • Tire rotation direction main groove measuring device 10 Line laser beam irradiation device 20: Camera 30: Data processing device 31: Control unit 32: Data processing unit 40: Tire 41: Tire rotation direction main groove 50: Table 310 : Line laser control unit 311: Imaging control unit 320: Line laser image detection unit 321: Light cutting line coordinate detection unit 322: Groove depth calculation unit 323: Main groove determination unit

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  • General Physics & Mathematics (AREA)
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  • Length Measuring Devices By Optical Means (AREA)

Abstract

[Problem] To provide a device that measures the depth of a rotational-direction main groove (circumferential main groove), of a tire, formed in the tread surface of the tire, the tire having been removed from the vehicle. [Solution] Line laser light is projected onto at least two different locations of a tread surface of a tire, and captured images of the line laser light at each location are acquired. Light sectioning line coordinates, which are coordinates of the image of the line laser light, are detected for each of the captured images. A depth of a groove formed in the tread surface is calculated on the basis of the triangulation method from each of the light sectioning line coordinates. Grooves, for which the rotational direction coordinates of the calculated depth of the groove match, are each defined as a rotational direction main groove. The groove depth thereof is determined to be the depth of each of the rotational direction main grooves.

Description

タイヤの回転方向主溝深さの測定方法、及びその方法を利用した回転方向主溝深さの測定装置METHOD FOR MEASURING ROTATIONAL DIRECTION MAIN GROOVE DEPTH OF TIRE AND ROTATIONAL DIRECTION MEASUREMENT DEVICE USING THE METHOD
 本発明は、自動車、バイク等のタイヤのトレッド面に形成された回転方向の主溝深さの測定に関し、タイヤの表面に照射したラインレーザ光の像（光切断線の像）を撮像し、その撮像画像に基づいてタイヤの回転方向主溝深さを測定する方法、及びその方法を利用した測定装置に関する。 The present invention relates to the measurement of the depth of the main groove in the rotational direction formed on the tread surface of a tire such as an automobile or motorcycle. The present invention relates to a method for measuring the depth of the main groove in the rotational direction of a tire based on the captured image, and a measuring apparatus using the method.
自動車等の車両のタイヤは、その損耗がある程度以上になると、車両の走行中に破損して、重大な事故の原因となるおそれがあるため、適切な時期に新品のタイヤと交換することが必要となっている。 Tires of vehicles such as automobiles, if worn beyond a certain level, may break while the vehicle is running and cause a serious accident, so it is necessary to replace them with new tires at an appropriate time. It has become.
タイヤの寿命は、車両の走行距離のみならず、その車種、常時走行する路面の状態や運転者のくせ等の個別要因によっても大幅に変動するので、新品タイヤへの交換時期を、走行距離のみによって判断するのは適切ではなく、個々のタイヤの損耗状態を調査して判断することが重要である。 Tire life depends not only on the mileage of the vehicle, but also on individual factors such as the type of vehicle, the condition of the road surface on which the tire is constantly driven, and the habits of the driver. It is not appropriate to make a judgment based on the number of tires, but it is important to investigate the wear condition of each tire and make a judgment.
タイヤの寿命を支配する主な要因として、トレッド面の摩耗と、ヒビ割れや切りキズ等のキズの発生があげられる。トレッド面の摩耗の進行状態は、タイヤの溝の深さから判断されることが多い。すなわち、路面とタイヤの間に挟まれた水をタイヤの後方又は側方に逃がすために、トレッド面にはタイヤの回転方向となる縦溝（周回溝）と横溝が形成されている。 The main factors that govern the life of tires are the wear of the tread surface and the occurrence of scratches such as cracks and cuts. The progress of wear on the tread surface is often judged from the depth of the tire groove. That is, longitudinal grooves (circumferential grooves) and lateral grooves are formed on the tread surface in the direction of rotation of the tire in order to release water trapped between the road surface and the tire to the rear or side of the tire.
摩耗によりゴムの肉厚が減少すると、これらの溝が浅くなるため、残溝深さを測定することにより、摩耗の程度を推認することができる。そのため、如何にして残溝深さの数値を測定するか、特に縦溝（周回溝、以下本明細書では回転方向主溝、又は単に主溝という。）の測定が、タイヤ損耗状態の調査の一つの課題となっている。 When the thickness of the rubber decreases due to wear, these grooves become shallower, so the degree of wear can be estimated by measuring the remaining groove depth. Therefore, how to measure the numerical value of the remaining groove depth, especially the measurement of the longitudinal groove (circumferential groove, hereinafter referred to as the main groove in the direction of rotation or simply the main groove in this specification), is the key to investigating the state of tire wear. This is one issue.
一般に、物体表面の形状を三次元的に測定する手段として、レーザ変位計が用いられることが多い。タイヤの残溝深さの測定にレーザ変位計を用いた事例も報告されている。例えば特許文献１は、タイヤをその回転軸の回りで回転させながら、タイヤのトレッド面に対して所定の方向から入射光を照射し、この入射光に対する所定の角度の反射光を受光部で受光して、タイヤ溝の深さのデータを取得する技術を開示している。しかし、レーザ変位計による残溝深さの測定には、以下のような問題があると考えられる。 In general, a laser displacement meter is often used as means for three-dimensionally measuring the shape of the surface of an object. There have also been reported cases of using a laser displacement gauge to measure the remaining groove depth of a tire. For example, in Patent Document 1, while rotating the tire around its rotation axis, the tread surface of the tire is irradiated with incident light from a predetermined direction, and the reflected light at a predetermined angle with respect to the incident light is received by a light receiving portion. and acquires tire tread depth data. However, it is considered that the measurement of the residual groove depth by the laser displacement gauge has the following problems.
すなわち、黒色のゴム表面で計測を行なうため、強いレーザパワーを必要とし、タイヤにダメージを与える危険性がある。また、拡散的な反射を起こす表面で局所的な干渉が発生するので、十分な測定精度を確保するためには、かなり複雑な操作手順が必要になるという問題がある。さらに、何よりも装置が高価になり、メンテナンスに多大の労力を要するという欠点がある。 That is, since the measurement is performed on the black rubber surface, a strong laser power is required and there is a risk of damaging the tire. In addition, since local interference occurs on surfaces that cause diffuse reflection, there is the problem that a fairly complicated operating procedure is required in order to ensure sufficient measurement accuracy. Furthermore, above all, there is a drawback that the equipment is expensive and maintenance requires a lot of labor.
一方、タイヤの残溝深さの測定をラインレーザ光の像（光切断線の像）を撮像し、その撮像画像に基づいて光切断法によりタイヤの溝深さを測定する方法が、下記特許文献２に開示されている。 On the other hand, a method of measuring the remaining groove depth of a tire by capturing an image of a line laser beam (image of a light-cutting line) and measuring the tire groove depth by the light-cutting method based on the imaged image is disclosed in the following patent. It is disclosed in Document 2.
下記特許文献２は、タイヤの移動方向を横切るように照射する光源として、レーザ或いはシャドーされた発光ダイオードにより扇状光線が作られる。測定はタイヤの表面に対して非直交的に行われるので、光源もセンサのいずれも直接反射の角度方向に位置しない。センサはこの場合２次元画像解析カメラである。評価は、測定したタイヤトレッドの包絡面（envelope）を生成することにより、そしてトレッド溝のもっとも深い箇所を探すことにより行われる。 In JP-A-2003-200003, a fan-shaped light beam is created by a laser or a shadowed light-emitting diode as a light source for irradiating transversely to the direction of travel of the tire. Since the measurements are made non-orthogonal to the surface of the tire, neither the light source nor the sensor are located at the angular direction of direct reflection. The sensor is in this case a two-dimensional image analysis camera. The evaluation is done by generating a measured tire tread envelope and looking for the deepest points of the tread grooves.
下記特許文献２に記載の技術によれば、光切断法によりトレッド溝の最も深い箇所がタイヤの残溝深さと判定される。しかし、タイヤのトレッド面にはタイヤの回転方向となる縦溝（周回溝）と横溝が形成されているので、判定した溝が縦溝（周回溝）であるか、それとも横溝であるか判別することができない。また、使用中のタイヤには様々な凹凸ができている場合もある。このため周回溝と判定した溝が、実は周回溝ではない、という場合もある、という問題がある。 According to the technique described in Patent Document 2 below, the deepest part of the tread groove is determined as the remaining groove depth of the tire by the light section method. However, since longitudinal grooves (circumferential grooves) and lateral grooves are formed on the tread surface of the tire in the direction of rotation of the tire, it is determined whether the determined grooves are longitudinal grooves (circumferential grooves) or lateral grooves. I can't. In addition, a tire in use may have various irregularities. Therefore, there is a problem that a groove determined to be a circumferential groove may not actually be a circumferential groove.
下記特許文献３は、相対的に移動する被測定物の表面（回転するタイヤの表面等）に照射したライン光の像（ 光切断線の像）を撮像し、その撮像画像に基づいて光切断法による形状検出を行うことによって被測定物の表面形状を検出する形状測定装置及びその方法を開示している。 The following Patent Document 3 captures an image of line light (image of a light-section line) irradiated on the surface of a relatively moving object to be measured (surface of a rotating tire, etc.), and light-section based on the captured image. Disclosed is a shape measuring apparatus and method for detecting the surface shape of an object to be measured by performing shape detection using a method.
下記特許文献３の技術は、被測定物の表面の検出高さ方向とは異なる方向から複数のライン光を照射することにより、被測定物の表面に被測定物の表面の移動方向である第１方向に直交する第２方向に伸びるとともに該第２方向において占める範囲が相互にずれている複数の分離した光切断線を形成させるライン光照射手段と、被測定物の表面に形成された複数の分離した光切断線の像を、複数のライン光それぞれの主光線が被測定物の表面に対して正反射する方向において撮像する撮像手段と、一定単位の前記移動に応じて前記撮像手段により得られる複数の撮像画像それぞれについて、撮像手段の撮像画像の座標系における前記複数の分離した光切断線それぞれに対応して予め設定された複数の独立した画像処理対象領域の画像それぞれから、光切断線の像の座標である光切断線座標を個別に検出する光切断線座標検出手段と、光切断線座標検出手段により検出された複数の光切断線座標に基づいて被測定物の第１方向における表面高さ分布を算出する表面形状算出手段とを具備してなることを特徴とする形状測定装置、である。 The technique of Patent Document 3 below irradiates the surface of the object to be measured with a plurality of line lights from a direction different from the detection height direction of the surface of the object to be measured. line light irradiation means for forming a plurality of separated light-section lines extending in a second direction orthogonal to one direction and having mutually displaced ranges in the second direction; and a plurality of lines formed on the surface of the object to be measured. an imaging means for imaging an image of the separated light-section line in the direction in which the principal ray of each of the plurality of line lights is specularly reflected on the surface of the object to be measured; For each of the plurality of captured images obtained, light sectioning is performed from each of the images of the plurality of independent image processing target regions preset corresponding to the plurality of separated light section lines in the coordinate system of the captured image of the imaging means. light-section line coordinate detecting means for individually detecting light-section line coordinates that are coordinates of the line image; and a first direction of the object to be measured based on the plurality of light-section line coordinates detected by the light-section line coordinate detection means and surface shape calculating means for calculating the surface height distribution in the shape measuring apparatus.
下記特許文献３が開示する形状測定装置は、例えばタイヤの形状を測定するにあたっては、タイヤを回転させながらタイヤの側面の形状、タイヤのトレッド面の形状を測定することで、タイヤ全体の形状を測定するものである。このため、この技術ではタイヤのトレッド面には分離した複数のライン光を照射し、かかるライン光の画像をそれぞれに対応した光切断線座標検出手段により座標検出することで、タイヤが回転していてもその処理に遅れが生じないようにしている。 For example, when measuring the shape of a tire, the shape measuring device disclosed in Patent Document 3 below measures the shape of the side surface of the tire and the shape of the tread surface of the tire while rotating the tire, thereby determining the shape of the entire tire. It is what you measure. For this reason, in this technology, a plurality of separated line lights are irradiated onto the tread surface of the tire, and the coordinates of the images of the line lights are detected by the light-section line coordinate detection means corresponding to each line light, so that the tire is rotating. Even if there is no delay in the processing.
このため、特許文献３に記載の技術でタイヤのトレッド面に形成されている主溝を測定するには、タイヤを回転させなければならず、また、タイヤの回転方向に対して横断する方向で分離したライン光を複数照射しなければならない。このため、測定装置が複雑でコスト高の測定装置になる、という問題がある。使用中のタイヤの摩耗状況を判別するには、タイヤの全体形状を測定する必要はなく、周回溝の深さを正確に測定することが必要である。 Therefore, in order to measure the main grooves formed on the tread surface of the tire by the technique described in Patent Document 3, the tire must be rotated, and in addition, the tire must be rotated in a direction transverse to the rotational direction of the tire. A plurality of separated line lights must be emitted. Therefore, there is a problem that the measuring device becomes a complicated and expensive measuring device. In order to determine the wear condition of a tire in use, it is not necessary to measure the overall shape of the tire, but it is necessary to accurately measure the depth of the circumferential groove.
特開平２０１６－１６１３６０号公報JP-A-2016-161360 特許第５６４００７３号公報Japanese Patent No. 5640073 特許第５０８９２８６号公報Japanese Patent No. 5089286
  冬季に路面に積雪や凍結をみる寒冷地の居住者や、積雪の無い地域の居住者であっても、業務やレジャーのため自家用車で積雪地に出掛ける場合は、夏用タイヤと冬用タイヤの使い分けを必要としている。そのため、冬季の始まりと終わりにタイヤ交換の作業を行う必要があり、また、使用しない方のタイヤをその期間保管しておくことが必要となる。 Even if you are a resident of a cold area where you see snow or ice on the road surface in winter, or a resident of an area where there is no snow, when you go to a snowy area by private car for work or leisure, summer tires and winter tires are recommended. It is necessary to use properly. Therefore, it is necessary to perform tire replacement work at the beginning and end of the winter season, and it is also necessary to store the unused tire during that period.
このタイヤの交換作業は、一般の自家用車ユーザーが自力で行なうことも可能であるが、かなりの腕力を要する荒仕事であるため、女性や高齢者の場合、これを専門に又は副業として行う事業者、例えばタイヤの量販店等に依存せざるを得ない。また、交換は自力で可能であっても、自宅に保管場所を確保できない場合も同様と考えられる。 Although it is possible for ordinary private car users to do this tire replacement work on their own, it is a rough job that requires considerable physical strength. Therefore, we have no choice but to rely on other companies, such as mass retailers of tires. In addition, even if the exchange can be done by oneself, the same situation can be considered in the case where it is not possible to secure a storage place at home.
かかるタイヤの交換・保管の事業者は、顧客（ユーザー）の安全走行に資するため、或いは顧客に適切な新品タイヤへの交換時期をアドバイスするため、タイヤの損耗状態、特にタイヤの回転方向の主溝の深さ（残溝）の情報を取得する、操作が簡単で低廉な価格の測定装置を求めている。 In order to contribute to the safe driving of customers (users), or to advise customers on the appropriate time to replace tires with new tires, such tire replacement and storage business operators should check the wear condition of tires, especially the direction of rotation of tires. There is a need for an easy-to-operate, low-cost measuring device that acquires groove depth (remaining groove) information.
そこで本発明は、自動車・バイク等の車両から取り外されたタイヤのトレッド面に形成されたタイヤの回転方向の主溝（周回主溝）の深さを測定する装置であって、装置の製作費やメンテナンスコストが安価であり、かつその測定操作も簡易に行なえるようなタイヤのトレッド面の回転方向主溝の深さを測定する装置を提供することを課題としている。 Therefore, the present invention is a device for measuring the depth of the main groove (circumferential groove) in the direction of rotation of the tire formed on the tread surface of the tire removed from a vehicle such as an automobile or motorcycle, and the manufacturing cost of the device is To provide a device for measuring the depth of the main groove in the rotational direction of the tread surface of a tire which is low in cost and maintenance cost and which can be easily measured.
  上記課題を解決するための本発明の第一は、ラインレーザ光をタイヤのトレッド面に、タイヤの回転方向に対して横断する方向で照射し、前記トレッド面のラインレーザ光の像をカメラで撮像し、撮像した撮像画像に基づいて光切断法により前記トレッド面に複数形成されている回転方向の主溝の深さを検出する回転方向主溝深さの測定方法であって、
前記トレッド面の異なる少なくとも２か所にラインレーザ光を照射し、前記ラインレーザ光の像をそれぞれ撮像し、
前記撮像したそれぞれの撮像画像について、前記ラインレーザ光の像の座標である光切断線座標を検出し、
前記光切断線座標から三角測量法に基づいて、前記トレッド面に形成された溝深さをそれぞれ算出し、
算出された前記溝の深さの回転方向の座標が略一致する溝の深さをそれぞれ回転方向主溝の深さと判定することを特徴とするタイヤのトレッド面に形成された回転方向主溝深さの測定方法、である。 The first aspect of the present invention for solving the above problems is to irradiate the tread surface of the tire with a line laser beam in a direction transverse to the rotation direction of the tire, and capture an image of the line laser beam on the tread surface with a camera. A method for measuring the depth of a main groove in the rotational direction, in which an image is captured and the depth of a plurality of main grooves in the rotational direction formed on the tread surface is detected by an optical section method based on the captured image,
irradiating at least two different locations on the tread surface with a line laser beam, and capturing images of the line laser beam, respectively;
Detecting light-section line coordinates, which are coordinates of the image of the line laser light, for each of the captured images,
calculating groove depths formed on the tread surface based on the triangulation method from the light-section line coordinates,
A depth of a main groove in the rotational direction formed on a tread surface of a tire, characterized in that a depth of the groove at which the coordinates in the rotational direction of the calculated depth of the groove substantially match each other is determined as the depth of the main groove in the rotational direction. How to measure the tightness.
 本発明の第二は、ラインレーザ光をタイヤのトレッド面に、タイヤの回転方向に対して横断する方向で照射し、前記トレッド面のラインレーザ光の像をカメラで撮像し、撮像した撮像画像に基づいて光切断法により前記トレッド面に複数形成されている回転方向の主溝の深さを検出する回転方向主溝深さの測定方法であって、
前記トレッド面の異なる少なくとも２か所にラインレーザ光を照射し、前記ラインレーザ光の像をそれぞれ取得し、
前記撮像したそれぞれの撮像画像について、前記ラインレーザ光の像の座標である光切断線座標を検出し、
前記光切断線座標の一座標であるＡ点と、前記Ａ点からタイヤの回転方向に対して横断する方向にｗ離れた前記光切断線座標の一座標であるＢ点と、前記Ａ点からタイヤの回転方向に対して横断する方向に２ｗ離れた前記光切断線座標の一座標であるＣ点とを選定し、前記Ａ点と前記Ｂ点と前記Ｃ点とで形成される三角形の面積を、前記Ａ点、前記Ｂ点、前記Ｃ点のいずれかが前記光切断線座標の全ての座標となるまで繰り返して求積し、
前記求積された前記三角形の面積から溝深さを算出し、
前記溝深さが所定値以上のものを、それぞれ主溝候補とし、
前記主溝候補の回転方向の座標が略一致する溝の深さをそれぞれ回転方向主溝の深さと判定することを特徴とするタイヤのトレッド面に形成された回転方向主溝深さの測定方法、である。 A second aspect of the present invention is a captured image obtained by irradiating the tread surface of a tire with a line laser beam in a direction transverse to the rotation direction of the tire, and capturing an image of the line laser beam on the tread surface with a camera. A method for measuring the depth of a main groove in the rotational direction for detecting the depth of a plurality of main grooves in the rotational direction formed on the tread surface by an optical section method based on,
irradiating at least two different places on the tread surface with a line laser beam, obtaining images of the line laser beam, respectively;
Detecting light-section line coordinates, which are coordinates of the image of the line laser light, for each of the captured images,
A point that is one coordinate of the light-section line coordinates, a point B that is one coordinate of the light-section line coordinates that is separated from the point A by w in a direction transverse to the rotation direction of the tire, and from the point A A point C, which is one coordinate of the light-section line coordinates separated by 2w in a direction transverse to the rotation direction of the tire, is selected, and the area of a triangle formed by the point A, the point B, and the point C is repeatedly quadratured until any one of the A point, the B point, and the C point becomes all the coordinates of the light-section line coordinates,
Calculate the groove depth from the quadrature area of the triangle,
The groove depth is a predetermined value or more, respectively, as a main groove candidate,
A method for measuring the depth of a main groove in the rotational direction formed on the tread surface of a tire, characterized in that the depth of the groove whose coordinates in the rotational direction substantially match the candidate main grooves is determined as the depth of the main groove in the rotational direction. , is.
 また、本発明の第三は、タイヤのトレッド面に、タイヤの回転方向に対して横断する方向でタイヤのトレッド面の少なくとも異なる２か所にラインレーザ光を照射するラインレーザ光照射装置と、
前記トレッド面のラインレーザ光の像を撮像するカメラと、
前記カメラで撮像された撮像画像からラインレーザ光の像を検出するラインレーザ画像検出部と、
前記ラインレーザ光の像の座標である光切断線座標を検出する光切断線座標検出部と、
前記光切断線座標から光切断法に基づいて、前記トレッド面に形成された溝の深さを算出する溝深さ算出部と、
算出された前記溝の深さの回転方向の座標が略一致する複数の溝をそれぞれ回転方向主溝と判定する主溝判定部
とを備えたことを特徴とするタイヤのトレッド面に形成された回転方向主溝深さの測定装置、である。 A third aspect of the present invention is a line laser beam irradiation device for irradiating a line laser beam onto at least two different locations on the tread surface of the tire in a direction transverse to the rotational direction of the tire;
a camera that captures an image of the line laser light on the tread surface;
a line laser image detection unit that detects an image of line laser light from an image captured by the camera;
a light-section line coordinate detection unit that detects light-section line coordinates that are coordinates of an image of the line laser light;
a groove depth calculator that calculates the depth of the grooves formed on the tread surface from the light-section line coordinates based on the light-section method;
a main groove determination unit configured to determine each of a plurality of grooves in which the coordinates of the calculated depth of the groove in the rotation direction substantially match each other as a rotation direction main groove. A device for measuring the depth of the main groove in the rotational direction.
  本発明においては、タイヤのトレッド面の少なくとも異なる２か所にラインレーザ光を照射し、タイヤのトレッド面のラインレーザ光の像をカメラで撮像する。撮像したそれぞれの撮像画像からラインレーザ光の像を検出し、ラインレーザ光の像の座標である光切断線座標を検出する。 In the present invention, line laser light is applied to at least two different locations on the tread surface of the tire, and an image of the line laser light on the tread surface of the tire is captured by a camera. An image of the line laser light is detected from each captured image, and light-section line coordinates, which are the coordinates of the image of the line laser light, are detected.
ラインレーザ光照射装置とカメラの配置と、光切断線座標とから、光切断法の原理を用いた三角測量法に基づいて、溝の深さを算出することができる。ラインレーザ光の像は少なくとも２つあり、光切断法により検出された溝の回転方向の座標が略一致する溝は縦溝となることから、その溝の深さを主溝の深さと判定する。これにより、例えば横溝やトレッド面にできた凹凸を回転方向の主溝と誤判定することを防止することができる。 The depth of the groove can be calculated from the arrangement of the line laser light irradiation device and the camera, and the coordinates of the light-cutting line, based on the triangulation method using the principle of the light-cutting method. There are at least two images of the line laser beam, and the grooves whose coordinates in the direction of rotation of the grooves detected by the light section method are substantially the same are the longitudinal grooves, so the depth of the groove is determined as the depth of the main groove. . As a result, it is possible to prevent erroneous determination of lateral grooves or irregularities formed on the tread surface as main grooves in the rotational direction.
上記による回転方向主溝の判定に加え、光切断線座標のそれぞれについて、前記光切断線座標の一座標であるＡ点と、前記Ａ点からタイヤの回転方向に対して横断する方向にｗ離れた前記光切断線座標の一座標であるＢ点と、前記Ａ点からタイヤの回転方向に対して横断する方向に２ｗ離れた前記光切断線座標の一座標であるＣ点とを選定し、前記Ａ点と前記Ｂ点と前記Ｃ点とで形成される三角形の面積を、記Ａ点、前記Ｂ点、前記Ｃ点のいずれかが前記光切断線座標の全ての座標となるまで繰り返して求積し、前記求積された前記三角形の面積から溝深さを算出し、前記溝深さが所定値以上であって、回転方向の座標が略一致する溝の深さをそれぞれ回転方向主溝の深さと判定する。 In addition to the determination of the rotational direction main grooves as described above, for each of the light-section line coordinates, a point A, which is one coordinate of the light-section line coordinates, and a distance w away from the point A in a direction transverse to the tire rotation direction point B, which is one coordinate of the light-section line coordinates, and point C, which is one coordinate of the light-section line coordinates, which is separated from the point A by 2w in a direction transverse to the rotation direction of the tire, The area of the triangle formed by the point A, the point B, and the point C is repeated until any one of the points A, B, and C becomes all the coordinates of the light-section line coordinates. A groove depth is calculated from the quadratured area of the triangle, and groove depths having the groove depth equal to or greater than a predetermined value and having substantially the same coordinates in the rotation direction are determined as main rotation directions. Determine the depth of the groove.
ここで、タイヤのトレッド面は緩やかな曲面であり、カメラで撮像されたラインレーザ光の像も緩やかな曲線となる。このため、溝深さの算出にあたっては溝部分で分断されている（離隔している）光切断線の法線と直交する方向で溝深さを算出する必要がある。そのためには、光切断線座標から３点を選定し、３点で構成される三角形の面積を、全ての光切断線座標について求積し、そこから得られた溝深さの最大値を溝深さと判定することが好適である。 Here, the tread surface of the tire is a gently curved surface, and the image of the line laser light picked up by the camera also has a gently curved surface. Therefore, when calculating the groove depth, it is necessary to calculate the groove depth in a direction perpendicular to the normal line of the light section line divided (separated) by the groove portion. For that purpose, 3 points are selected from the light-section line coordinates, the area of the triangle composed of the 3 points is quadratured for all the light-section line coordinates, and the maximum value of the groove depth obtained from there is calculated as the groove Depth is preferably determined.
上記の３点は、光切断線座標の一座標であるＡ点を選定し、Ａ点からタイヤの回転方向に対して横断する方向にｗ離れた光切断線座標の一座標であるＢ点と、Ａ点からタイヤの回転方向に対して横断する方向に２ｗ離れた光切断線座標の一座標であるＣ点とする。そして、Ａ点とＢ点とＣ点とで形成される三角形の面積を、Ａ点、Ｂ点、Ｃ点のいずれかが光切断線座標の全ての座標となるまで繰り返して求積し、最大面積から溝深さを算出する。上記ｗ（三角形の底辺）は、少なくとも測定するタイヤの主溝の幅とし、その幅以上であって２倍以下の幅とすることが好適である。 For the above three points, point A, which is one coordinate of light-section line coordinates, is selected, and point B, which is one coordinate of light-section line coordinates, is separated from point A by w in a direction transverse to the rotation direction of the tire. , point C, which is one coordinate of the light-section line coordinates separated from point A by 2w in a direction transverse to the tire rotation direction. Then, the area of the triangle formed by points A, B, and C is repeatedly quadratured until any one of points A, B, and C reaches all the coordinates of the light-section line coordinates, and the maximum Calculate the groove depth from the area. The above w (the base of the triangle) is at least the width of the main groove of the tire to be measured, and is preferably not less than the width but not more than twice the width.
  本発明により、自動車・バイク等の車両から取り外されたタイヤのトレッド面に形成されたタイヤの回転方向の主溝（周回主溝）の深さを測定する装置であって、装置の製作費やメンテナンスコストが安価であり、かつその測定操作も簡易に行なえるようなタイヤのトレッド面の回転方向主溝の深さを測定する装置を提供することが可能になった。本発明のタイヤのトレッド面に形成されている回転方向主溝の深さの測定装置は、設備コストが安価で、メンテナンスが容易であり、かつ測定の手間も簡易であるという特徴を有している。 According to the present invention, a device for measuring the depth of the main groove (circumferential groove) in the direction of rotation of the tire formed on the tread surface of the tire removed from a vehicle such as an automobile or motorcycle, It has become possible to provide a device for measuring the depth of the main groove in the rotational direction of the tread surface of a tire, which is low in maintenance cost and easy to measure. The apparatus for measuring the depth of the rotational direction main groove formed on the tread surface of a tire according to the present invention is characterized by low equipment cost, easy maintenance, and simple measurement. there is
以下、実施例の図面を参照して、本発明の好ましい実施形態について説明する。図１は、本発明の第一の実施例であるタイヤのトレッド面に形成された回転方向主溝深さの測定装置１の構成を示す斜視図である。この装置は、タイヤ４０を載置するテーブル５０、ラインレーザ光照射装置１０、ラインレーザ光の像を撮像するカメラ２０、及びカメラの撮像画像を分析処理するデータ処理装置３０を備えている。なお、図１には図示していないが、環境条件に応じてタイヤ４０のトレッド面を明瞭にする光源を備えるこることは好適である。 Preferred embodiments of the present invention will now be described with reference to the drawings of examples. FIG. 1 is a perspective view showing the construction of a measuring apparatus 1 for measuring the depth of a main groove in the tread surface of a tire according to the first embodiment of the present invention. This apparatus includes a table 50 on which a tire 40 is placed, a line laser light irradiation device 10, a camera 20 for capturing an image of the line laser light, and a data processing device 30 for analyzing and processing the image captured by the camera. Although not shown in FIG. 1, it is preferable to provide a light source that makes the tread surface of the tire 40 clear according to environmental conditions.
タイヤ４０は、テーブル５０上にタイヤ側面が水平になるように載置される。ラインレーザ光照射装置１０は、カメラ２０を中心に対称に配置され、タイヤ４０のトレッド面にラインレーザ光をタイヤの回転方向に対して横断する方向に照射し、トレッド面の異なる２か所にラインレーザ光の像を形成する。カメラ２０は、トレッド面の異なる２か所に現れるラインレーザ光の像を撮像し、撮像した画像はデータ処理装置３０に送られる。ラインレーザ光の画像は、タイヤ４０の残溝深さの情報を得ることを目的にするものである。なお、図１に示す一実施例においては、カメラ２０を２つのラインレーザ光照射装置１０の中間に配置しているが、本発明はこれに限定されるものではなく、光切断法の原理に用いられている三角測量法で必要となるカメラ２０とラインレーザ光照射装置１０と、タイヤのトレッド面との配置（高さ、離隔、角度等）関係が特定できれば良い。 The tire 40 is placed on the table 50 so that the tire side surface is horizontal. The line laser beam irradiation device 10 is arranged symmetrically with respect to the camera 20, and irradiates the tread surface of the tire 40 with line laser beams in a direction transverse to the rotation direction of the tire so as to irradiate two different points on the tread surface. Forms an image of line laser light. The camera 20 captures images of line laser light appearing at two different locations on the tread surface, and the captured images are sent to the data processing device 30 . The purpose of the line laser light image is to obtain information on the remaining groove depth of the tire 40 . In the embodiment shown in FIG. 1, the camera 20 is arranged between the two line laser light irradiation devices 10, but the present invention is not limited to this, and is based on the principle of the light section method. It suffices if the arrangement (height, distance, angle, etc.) relationship between the camera 20, the line laser beam irradiation device 10, and the tread surface of the tire, which is necessary for the triangulation method used, can be specified.
本発明は、タイヤの回転方向に対して横断する方向で、トレッド面のラインレーザ光の像を取得するに際して、トレッド面の異なる２か所にラインレーザ光を照射し、そのカメラ２０で取像するところに特徴がある。これはトレッド面には回転方向の主溝の他、横溝や斜溝が形成されており、また使用によりトレッド面に凹凸が生じている場合がある。トレッド面の異なる２か所にラインレーザ光を照射するのは、回転方向主溝とその他の溝とを判別するためである。ここで、ラインレーザ光の照射はトレッド面の異なる２か所に同時に照射することが好適であるが、時間をずらせてトレッド面の異なる２か所にラインレーザ光を照射した画像を合成処理することで行っても良い。 In the present invention, when acquiring a line laser beam image of the tread surface in a direction transverse to the rotating direction of the tire, two different locations on the tread surface are irradiated with the line laser beam and captured by the camera 20. There is a feature in the place to do. This is because the tread surface is formed with lateral grooves and oblique grooves in addition to the main grooves in the direction of rotation, and the tread surface may become uneven due to use. The reason why the line laser light is applied to two different places on the tread surface is to distinguish between the main grooves in the rotational direction and the other grooves. Here, it is preferable to simultaneously irradiate two different locations on the tread surface with the line laser beam. You can go with that.
本発明では、こられの様々な溝と回転方向主溝との判別をするにあたって、回転方向主溝は必ず回転方向に溝が連続しているという特徴を利用した。即ち、ラインレーザ光の像である光切断線１１（図３参照）の座標から、回転方向の座標がほぼ一致する溝を回転方向主溝として判別しており、この点が本発明の一つのポイントとなっている。ただし、タイヤ回転方向に主溝が蛇行した形状で形成される場合もあり、また、横溝との関係で必ずしも回転方向に連続していない主溝が形成されている場合もある。かかる主溝であっても、光切断線１１の座標から、回転方向の座標がほぼ一致する溝を回転方向主溝として判別する。 In the present invention, in distinguishing between these various grooves and rotational direction main grooves, the characteristic that the rotational direction main grooves are always continuous in the rotational direction is used. That is, from the coordinates of the light cutting line 11 (see FIG. 3), which is the image of the line laser beam, the grooves whose coordinates in the rotation direction are substantially the same are determined as the main grooves in the rotation direction. It is a point. However, there are cases where the main grooves are formed in a meandering shape in the tire rotation direction, and there are cases where the main grooves are not necessarily continuous in the rotation direction due to the relationship with the lateral grooves. Even with such a main groove, from the coordinates of the light-section line 11, grooves whose coordinates in the rotational direction are substantially the same are determined as rotational direction main grooves.
図２は、図１に示す本発明の一実施例である測定装置１のカメラ２０と、ラインレーザ光照射装置１０と、タイヤ４０のトレッド面と、回転方向主溝４１との高さ方向の位置関係を示した図である。ラインレーザ光照射装置１０はカメラ２０を挟んでタイヤ４０の回転方向に対称に配置されている。 FIG. 2 shows the height direction of the camera 20 of the measuring device 1 according to the embodiment of the present invention shown in FIG. It is a figure showing positional relationship. The line laser beam irradiation devices 10 are arranged symmetrically in the rotation direction of the tire 40 with the camera 20 interposed therebetween.
図２においては、ラインレーザ光照射装置１０の照射角度は、測定対象であるタイヤ４０の中心を照射する角度としている。測定するタイヤの径は様々であるが、例えば、最小径のタイヤの中心を照射する角度として設定する。カメラ２０のトレッド面からの高さは、２つのラインレーザ光の像が取得できる（視野角が確保できる）高さとし、その高さと同じ高さでカメラ２０を設置する。タイヤ４０の回転方向主溝４１の深さをＤとし、タイヤ４０のトレッド面へのラインレーザ光１００の入射角をθ、主溝４１の幅をｗとすると、Ｄ＝tanθ×ｗとなる。ここでｗは主溝４１の幅よりも広く、例えば主溝４１の幅の１倍から２倍程度とすることが好適である。これはタイヤの消耗により主溝の幅が変化する場合があること、またタイヤ回転方向に主溝が蛇行した形状で形成される場合があるからである。 In FIG. 2, the irradiation angle of the line laser beam irradiation device 10 is an angle for irradiating the center of the tire 40, which is the object to be measured. Although the diameter of the tire to be measured varies, for example, the angle for irradiating the center of the tire with the smallest diameter is set. The height of the camera 20 from the tread surface is set to a height at which images of two line laser beams can be acquired (a viewing angle can be secured), and the camera 20 is installed at the same height as that height. If D is the depth of the rotational direction main groove 41 of the tire 40, θ is the incident angle of the line laser beam 100 onto the tread surface of the tire 40, and w is the width of the main groove 41, then D=tan θ×w. Here, w is wider than the width of the main groove 41, and is preferably about 1 to 2 times the width of the main groove 41, for example. This is because the width of the main groove may change due to wear of the tire, and the main groove may be formed in a meandering shape in the tire rotation direction.
 図３は、タイヤをその側面が水平になるように載置し、ラインレーザ光照射装置１０によりタイヤ４０のトレッド面にラインレーザ光を照射している図である。２台のラインレーザ光照射装置１０からラインレーザ光１００がトレッド面の異なる２カ所に照射され、トレッド面にラインレーザ光の像である光切断線１１が２つ現れている。光切断線１１の像は、タイヤの回転方向主溝４１が形成されている箇所では、トレッド面からの反射による像ではなく、主溝４１の底面からの反射による像として現れる。即ち、図２（ｂ）に示すように光切断線１１の主溝４１の光切断線１１の像は、トレッド面に現れる像よりも、主溝４１の深さに応じてラインレーザ光１００の照射方向側に現れる。 FIG. 3 is a diagram of a tire placed with its side surface horizontal, and a line laser beam emitted from the line laser beam irradiation device 10 to the tread surface of the tire 40 . Line laser beams 100 are irradiated from two line laser beam irradiation devices 10 to two different locations on the tread surface, and two light cutting lines 11, which are images of the line laser beams, appear on the tread surface. The image of the light cutting line 11 appears not as an image reflected from the tread surface but as an image reflected from the bottom surface of the main groove 41 at the location where the tire rotational direction main groove 41 is formed. That is, as shown in FIG. 2(b), the image of the light cutting line 11 of the main groove 41 of the light cutting line 11 is more sensitive to the depth of the main groove 41 than the image appearing on the tread surface. Appears on the irradiation direction side.
上述したが、本発明ではトレッド面に形成されている回転方向主溝を、横溝や凹凸と区別するため、回転方向主溝は回転方向に溝が連続しているという特徴を判別手段として用いている。即ち、トレッド面にラインレーザ光の像を２つ生じさせ、それらのラインレーザ光の像である光切断線１１（光切断線１１－１、光切断線１１－２）の座標（光切断線座標）から、回転方向の座標が一致する溝を回転方向主溝として判別している。 As described above, in the present invention, in order to distinguish the main grooves in the rotational direction formed on the tread surface from the lateral grooves and the irregularities, the characteristic that the main grooves in the rotational direction are continuous in the rotational direction is used as a discriminating means. there is That is, two line laser light images are generated on the tread surface, and the coordinates of the light cutting lines 11 (light cutting line 11-1, light cutting line 11-2) that are the images of the line laser light (light cutting line coordinates), grooves with matching coordinates in the direction of rotation are determined as main grooves in the direction of rotation.
図４はラインレーザ光の像である光切断線１１から回転方向主溝の深さを算出する本発明の一実施例を示した図である。実物のタイヤにゲージをあてて溝深さを測定する場合には、タイヤ溝ゲージ（タイヤ溝デプスゲージ）をトレッド面の法線方向に設置し、トレッド面の法線と直角に測定針が溝底に当たるようにして溝深さを測定している。これはトレッド面が緩やかな曲面となっているためである。本発明の一実施例である回転方向主溝の測定装置１によるトレッド面に形成されるラインレーザ光の像も緩やかな曲線として現れる。 FIG. 4 is a diagram showing an embodiment of the present invention in which the depth of the main groove in the rotational direction is calculated from the light cutting line 11, which is the image of the line laser light. When measuring the groove depth by applying a gauge to the actual tire, install the tire groove gauge (tire groove depth gauge) in the direction normal to the tread surface, and point the measuring needle at the groove bottom at a right angle to the normal to the tread surface. The groove depth is measured so that it hits the This is because the tread surface is a gently curved surface. An image of the line laser beam formed on the tread surface by the measuring apparatus 1 for the rotational direction major grooves, which is an embodiment of the present invention, also appears as a gentle curve.
上述したように主溝の深さはトレッド面のラインレーザ光の像と、主溝のラインレーザ光の像との離隔ｈにより三角測量法で算出することができる。しかし、トレッド面の光切断線座標と、主溝の光切断線座標との離隔は、座標の取り方によって相違する。なお、図４に示す座標軸は、トレッド面を撮像した画像の解像度を１０００×１０００ドット、即ち、Ｘ軸の座標は０～１０００とし、Ｙ軸の座標も０～１０００とした。 As described above, the depth of the main groove can be calculated by the triangulation method from the distance h between the line laser light image of the tread surface and the line laser light image of the main groove. However, the distance between the light-section line coordinates of the tread surface and the light-section line coordinates of the main groove differs depending on how the coordinates are taken. The coordinate axes shown in FIG. 4 represent the resolution of an image of the tread surface of 1000×1000 dots, that is, the coordinates of the X-axis are 0-1000 and the coordinates of the Y-axis are 0-1000.
図４に示す光切断線１１から主溝の深さを算出する一手法として、光切断線１１の一座標であるＡ点と、Ａ点からタイヤの回転方向に対して横断する方向にｗ離れた光切断線１１の一座標であるＢ点と、Ａ点からタイヤの回転方向に対して横断する方向に２ｗ離れた光切断線１１の一座標であるＣ点とを選定する。 As a method for calculating the depth of the main groove from the light-section line 11 shown in FIG. A point B, which is one coordinate of the light-section line 11, and a point C, which is one coordinate of the light-section line 11, which is separated from the point A by 2w in a direction transverse to the rotating direction of the tire are selected.
そして、Ａ点とＢ点とＣ点とで形成される三角形の面積を求める。これをＡ点、又はB点、あるいはＣ点のいずれかが光切断線１１の全ての座標となるまで繰り返して求積し、これにより求積された三角形の面積を光切断線１１のＹ座標値をＸ軸、三角形の面積をＹ軸としてグラフ化すると、図４（ｂ）のような図を得る。こうして得られた三角形の面積の最大値から、それぞれの溝深さを算出し、それぞれ算出した溝深さのうち、所定の深さ以上、例えば、スリップサインが示す溝深さ（四輪の場合は１．６ｍｍ、二輪の場合は０．８ｍｍ）以上である箇所の溝を主溝の深さと判定する。 Then, the area of a triangle formed by points A, B, and C is obtained. This is repeated until all the coordinates of the light-section line 11 are obtained by either point A, point B, or point C, and the area of the resulting triangle is calculated as the Y-coordinate If the value is plotted on the X-axis and the area of the triangle is plotted on the Y-axis, a diagram such as that shown in FIG. 4B is obtained. From the maximum area of the triangle obtained in this way, each groove depth is calculated. is 1.6 mm, and 0.8 mm for two-wheels) or more is determined as the depth of the main groove.
図５は、本発明の一実施例であるタイヤのトレッド面に形成された回転方向主溝深さの測定装置１の構成を示すブロック図である。２台のラインレーザ光照射装置１０は、タイヤのトレッド面の異なる箇所にラインレーザ光を照射する。カメラ２０はトレッド面に現れるラインレーザ光の像を撮像する。ラインレーザ光照射装置１０の制御は、制御部３１のラインレーザ制御部３１０が行い、カメラ２０の制御は制御部３１の撮像制御部３１１が行う。 FIG. 5 is a block diagram showing the configuration of a measuring device 1 for measuring the depth of a main groove in the tread surface of a tire according to one embodiment of the present invention. The two line laser beam irradiation devices 10 irradiate line laser beams to different locations on the tread surface of the tire. A camera 20 captures an image of the line laser light appearing on the tread surface. The line laser control section 310 of the control section 31 controls the line laser light irradiation device 10 , and the imaging control section 311 of the control section 31 controls the camera 20 .
カメラ２０により撮像された画像は、データ処理部３２に送られる。データ処理部３２は、ラインレーザ光の像を検出するラインレーザ画像検出部３２０、ラインレーザ画像検出部３２０で検出されたラインレーザ光の像の座標である光切断線座標を検出する光切断線座標検出部３２１、光切断線座標検出部３２１による座標から溝深さを算出する溝深さ算出部３２２、そして溝深さ算出部３２２により算出された溝深と、光切断線１１の座標とから、回転方向主溝を判定する主溝判定部３２３とを備える。 An image captured by the camera 20 is sent to the data processing section 32 . The data processing unit 32 includes a line laser image detection unit 320 that detects an image of the line laser light, and a light cutting line that detects the coordinates of the line laser light image detected by the line laser image detection unit 320. A coordinate detection unit 321, a groove depth calculation unit 322 that calculates the groove depth from the coordinates by the light-section line coordinate detection unit 321, and the groove depth calculated by the groove depth calculation unit 322 and the coordinates of the light-section line 11. , a main groove determination unit 323 for determining the rotational direction main groove.
図６はタイヤ（サイズ：215/55R17）を本発明の一実施例であるタイヤのトレッド面に形成された回転方向主溝深さの測定装置１により得られた回転方向主溝の深さの図である。ラインレーザは波長が600nm、消費電力が40mW、電源電圧：5VDを用い、カメラ２０の解像度は2048x1536である。かかる仕様で取得した画像を処理し、光切断線１１の座標を求め、回転方向主溝深さを算出した結果、トレッド面に３本形成されている主溝４１の深さとして、５．４ｍｍから５．９ｍｍの深さが検出された。 FIG. 6 shows the depth of the main groove in the rotational direction of the tire (size: 215/55R17) obtained by measuring the depth of the main groove in the rotational direction formed on the tread surface of the tire according to one embodiment of the present invention. It is a diagram. The line laser has a wavelength of 600 nm, a power consumption of 40 mW, a power supply voltage of 5 VD, and a resolution of the camera 20 of 2048×1536. The image acquired with such specifications was processed, the coordinates of the light cutting line 11 were obtained, and the depth of the main groove in the rotational direction was calculated. A depth of 5.9 mm was detected from
図７は本発明の一実施例である回転方向主溝深さの測定方法の一例を示すフローチャートである。タイヤのトレッド面に２本のラインレーザ光を照射することによりトレッド面に現れるラインレーザ光の像の部分を強調し、フィルター処理を行う（Ｓ１,Ｓ２）。次に、ラインレーザ光の像を２色、例えば、赤と白、あるいは黒と白に二値化した後、ノイズを除去する処理を行う（Ｓ３,Ｓ４）。 FIG. 7 is a flow chart showing an example of a method for measuring the depth of the main groove in the rotational direction according to one embodiment of the present invention. By irradiating the tread surface of the tire with two line laser beams, the portion of the image of the line laser beams appearing on the tread surface is emphasized and filtered (S1, S2). Next, after binarizing the image of the line laser light into two colors, for example, red and white or black and white, noise is removed (S3, S4).
　次に、２つのラインレーザ光の像の線幅を、各座標の平均から、例えば１ドットに調整（１画素＝１ドット）する。また、本来は存在するラインレーザ光の像であるが消えている画素（欠損点）を線形補完し（Ｓ５,Ｓ６）、ラインレーザ光の像である光切断線１１の座標を抽出する（Ｓ７）。 Next, the line width of the two line laser light images is adjusted from the average of each coordinate to, for example, 1 dot (1 pixel = 1 dot). In addition, linear interpolation is performed on pixels (defective points) that originally exist in the image of the line laser beam but have disappeared (S5, S6), and the coordinates of the light cutting line 11, which is the image of the line laser beam, are extracted (S7). ).
次に、各光切断線１１の座標から、Ａ点、Ｂ点、Ｃ点を選定し、Ａ点、Ｂ点、Ｃ点で形成される三角形の面積を求積する（Ｓ８，Ｓ９）。Ａ点が全ての光切断線１１の座標となるまでこれを繰り返して、Ａ点、Ｂ点、Ｃ点で形成される三角形の面積を求積し（Ｓ１０）、三角形の面積をＹ軸とし、光切断線１１のＹ軸座標をＸ軸とするグラフの最大値を主溝の候補とする（Ｓ１１）。 Next, points A, B, and C are selected from the coordinates of each light-section line 11, and the area of a triangle formed by points A, B, and C is quadratured (S8, S9). This is repeated until the point A becomes the coordinate of all the light-section lines 11, the area of the triangle formed by the points A, B, and C is quadratured (S10), the area of the triangle is taken as the Y axis, The maximum value of the graph with the Y-axis coordinate of the light cutting line 11 as the X-axis is taken as a main groove candidate (S11).
各光切断線座標から求めた主溝の候補のなかから、光切断線１１のＹ座標がほぼ一致する、例えば、主溝の候補のなかで、回転方向主溝の幅以上にＹ座標が外れていないものを回転方向主溝と判定する。そして主溝と判定されたものの面積から主溝の深さを算出する（Ｓ１２，Ｓ１３）。 Among the candidates for the main groove obtained from the coordinates of each light-section line, the Y-coordinate of the light-section line 11 is substantially the same. If not, it is determined to be the main groove in the rotational direction. Then, the depth of the main groove is calculated from the area of the groove determined to be the main groove (S12, S13).
本発明の一実施例であるタイヤのトレッド面に形成されたタイヤの回転方向主溝深さの測定装置の構成を示す斜視図である。BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing the configuration of a tire rotation direction main groove depth measuring device formed on a tread surface of a tire according to an embodiment of the present invention; 本発明の一実施例であるタイヤの回転方向主溝の測定装置のカメラとラインレーザ光照射装置と、タイヤのトレッド面との位置関係を高さ方向で示した図である。BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view showing the positional relationship in the height direction between a camera, a line laser beam irradiation device, and a tread surface of a tire of a tire rotation direction main groove measuring device according to an embodiment of the present invention; 本発明の一実施例であるラインレーザ照射装置によりタイヤのトレッド面にラインレーザ光を照射しているラインレーザ光の照射図である。FIG. 2 is an irradiation diagram of line laser light that is applied to the tread surface of a tire by a line laser irradiation device that is an embodiment of the present invention. ラインレーザ光の像である切断線座標１１から回転方向主溝の深さを算出する本発明の一実施例を示した図である。FIG. 4 is a diagram showing an embodiment of the present invention in which the depth of the main groove in the rotational direction is calculated from the cutting line coordinates 11 that are the image of the line laser beam. 本発明の一実施例であるタイヤのトレッド面に形成された回転方向主溝深さの測定装置１の構成を示すブロック図である。1 is a block diagram showing the configuration of a measuring device 1 for measuring the depth of a main groove in the tread surface of a tire according to an embodiment of the present invention; FIG. 本発明の一実施例であるラインレーザ照射装置により得られた回転方向主溝の深さの図である。FIG. 4 is a diagram of the depth of a rotational direction main groove obtained by a line laser irradiation device that is an embodiment of the present invention; 本発明の一実施例であるタイヤのトレッド面に形成された回転方向主溝深さの測定方法の一例を示すフローチャートである。4 is a flow chart showing an example of a method for measuring the depth of the main groove in the rotational direction formed on the tread surface of the tire according to one embodiment of the present invention.
１：タイヤの回転方向主溝の測定装置
１０：ラインレーザ光照射装置
２０：カメラ
３０：データ処理装置
３１：制御部
３２：データ処理部
４０：タイヤ
４１：タイヤの回転方向主溝
５０：テーブル
３１０：ラインレーザ制御部
３１１：撮像制御部
３２０：ラインレーザ画像検出部
３２１：光切断線座標検出部
３２２：溝深さ算出部
３２３：主溝判定部

  1: Tire rotation direction main groove measuring device 10: Line laser beam irradiation device 20: Camera 30: Data processing device 31: Control unit 32: Data processing unit 40: Tire 41: Tire rotation direction main groove 50: Table 310 : Line laser control unit 311: Imaging control unit 320: Line laser image detection unit 321: Light cutting line coordinate detection unit 322: Groove depth calculation unit 323: Main groove determination unit

Claims (6)

  1. ラインレーザ光をタイヤのトレッド面に、タイヤの回転方向に対して横断する方向で照射し、前記トレッド面のラインレーザ光の像をカメラで撮像し、撮像した撮像画像に基づいて光切断法により前記トレッド面に複数形成されている回転方向の主溝の深さを検出する回転方向主溝深さの測定方法であって、
    前記トレッド面の異なる少なくとも２か所にラインレーザ光を照射し、前記ラインレーザ光の像をそれぞれ撮像し、
    前記撮像したそれぞれの撮像画像について、前記ラインレーザ光の像の座標である光切断線座標を検出し、
    前記光切断線座標から三角測量法に基づいて、前記トレッド面に形成された溝深さをそれぞれ算出し、
    算出された前記溝の深さの回転方向の座標が略一致する溝の深さをそれぞれ回転方向主溝の深さと判定することを特徴とするタイヤのトレッド面に形成された回転方向主溝深さの測定方法。　     A line laser beam is applied to the tread surface of the tire in a direction transverse to the direction of rotation of the tire, an image of the line laser beam on the tread surface is captured by a camera, and a light section method is performed based on the captured image. A method for measuring a depth of a main groove in the rotational direction, which detects the depth of a plurality of main grooves in the rotational direction formed on the tread surface,
    irradiating at least two different locations on the tread surface with a line laser beam, and capturing images of the line laser beam, respectively;
    Detecting light-section line coordinates, which are coordinates of the image of the line laser light, for each of the captured images,
    calculating groove depths formed on the tread surface based on the triangulation method from the light-section line coordinates,
    A depth of a main groove in the rotational direction formed on a tread surface of a tire, characterized in that a depth of the groove at which the coordinates in the rotational direction of the calculated depth of the groove substantially match each other is determined as the depth of the main groove in the rotational direction. How to measure tightness.
  2. ラインレーザ光をタイヤのトレッド面に、タイヤの回転方向に対して横断する方向で照射し、前記トレッド面のラインレーザ光の像をカメラで撮像し、撮像した撮像画像に基づいて光切断法により前記トレッド面に複数形成されている回転方向の主溝の深さを検出する回転方向主溝深さの測定方法であって、
    前記トレッド面の異なる少なくとも２か所にラインレーザ光を照射し、前記ラインレーザ光の像をそれぞれ取得し、
    前記撮像したそれぞれの撮像画像について、前記ラインレーザ光の像の座標である光切断線座標を検出し、
    前記光切断線座標の一座標であるＡ点と、前記Ａ点からタイヤの回転方向に対して横断する方向にｗ離れた前記光切断線座標の一座標であるＢ点と、前記Ａ点からタイヤの回転方向に対して横断する方向に２ｗ離れた前記光切断線座標の一座標であるＣ点とを選定し、前記Ａ点と前記Ｂ点と前記Ｃ点とで形成される三角形の面積を、前記Ａ、前記Ｂ点、前記Ｃ点のいずれかが前記光切断線座標の全ての座標となるまで繰り返して求積し、
    前記求積された前記三角形の面積から溝深さを算出し、
    前記溝深さが所定値以上のものを、それぞれ主溝候補とし、
    前記主溝候補の回転方向の座標が略一致する溝の深さをそれぞれ回転方向主溝の深さと判定することを特徴とするタイヤのトレッド面に形成された回転方向主溝深さの測定方法。     A line laser beam is applied to the tread surface of the tire in a direction transverse to the direction of rotation of the tire, an image of the line laser beam on the tread surface is captured by a camera, and a light section method is performed based on the captured image. A method for measuring a depth of a main groove in the rotational direction, which detects the depth of a plurality of main grooves in the rotational direction formed on the tread surface,
    irradiating at least two different places on the tread surface with a line laser beam, obtaining images of the line laser beam, respectively;
    Detecting light-section line coordinates, which are coordinates of the image of the line laser light, for each of the captured images,
    A point that is one coordinate of the light-section line coordinates, a point B that is one coordinate of the light-section line coordinates that is separated from the point A by w in a direction transverse to the rotation direction of the tire, and from the point A A point C, which is one coordinate of the light-section line coordinates separated by 2w in a direction transverse to the rotation direction of the tire, is selected, and the area of a triangle formed by the point A, the point B, and the point C is repeatedly quadratured until any one of the A, the B points, and the C points becomes all the coordinates of the light-section line coordinates,
    Calculate the groove depth from the quadrature area of the triangle,
    The groove depth is a predetermined value or more, respectively, as a main groove candidate,
    A method for measuring the depth of a main groove in the rotational direction formed on the tread surface of a tire, characterized in that the depth of the groove whose coordinates in the rotational direction substantially match the candidate main grooves is determined as the depth of the main groove in the rotational direction. .
  3. 前記ｗは前記回転方向主溝の幅以上であり、前記所定値は前記回転方向主溝に設けられているスリップサインの値以上であることを特徴とする請求項２に記載のタイヤのトレッド面に形成された主溝の深さの測定方法。 3. The tread surface of a tire according to claim 2, wherein said w is equal to or greater than the width of said rotational direction main groove, and said predetermined value is equal to or greater than a value of a slip sign provided in said rotational direction main groove. Method of measuring the depth of the main groove formed in
  4. タイヤのトレッド面に、タイヤの回転方向に対して横断する方向でタイヤのトレッド面の少なくとも異なる２か所にラインレーザ光を照射するラインレーザ光照射装置と、
    前記トレッド面のラインレーザ光の像を撮像するカメラと、
    前記カメラで撮像された撮像画像からラインレーザ光の像を検出するラインレーザ画像検出部と、
    前記ラインレーザ光の像の座標である光切断線座標を検出する光切断線座標検出部と、
    前記光切断線座標から光切断法に基づいて、前記トレッド面に形成された溝の深さを算出する溝深さ算出部と、
    算出された前記溝の深さの回転方向の座標が略一致する複数の溝をそれぞれ回転方向主溝と判定する主溝判定部
    とを備えたことを特徴とするタイヤのトレッド面に形成された回転方向主溝深さの測定装置。　     a line laser beam irradiation device for irradiating at least two different locations on the tread surface of the tire with line laser beams in a direction transverse to the rotational direction of the tire;
    a camera that captures an image of the line laser light on the tread surface;
    a line laser image detection unit that detects an image of line laser light from an image captured by the camera;
    a light-section line coordinate detection unit that detects light-section line coordinates that are coordinates of an image of the line laser light;
    a groove depth calculator that calculates the depth of the grooves formed on the tread surface from the light-section line coordinates based on the light-section method;
    a main groove determination unit configured to determine each of a plurality of grooves in which the coordinates of the calculated depth of the groove in the rotation direction substantially match each other as a rotation direction main groove. A device for measuring the depth of the main groove in the direction of rotation.
  5. 前記主溝判定部は、前記光切断線座標の一座標であるＡ点と、前記Ａ点からタイヤの回転方向に対して横断する方向にｗ離れた前記光切断線座標であるＢ点と、前記Ａ点からタイヤの回転方向に対して横断する方向に２ｗ離れた前記光切断線座標であるＣ点とを選定し、前記Ａ点と前記Ｂ点と前記Ｃ点とで形成される三角形の面積を、前記Ａ点、前記Ｂ点、前記Ｃ点のいずれかが前記光切断線座標の全ての座標となるまで繰り返して求積し、求積された前記三角形の面積から溝深さを算出する手段を更に備えたことを特徴とする請求項４に記載の回転方向主溝深さの測定装置。 The main groove determination unit includes a point A that is one coordinate of the light-section line coordinates, a point B that is the light-section line coordinates that are separated by w from the point A in a direction transverse to the rotation direction of the tire, A point C, which is the coordinate of the light section line, is separated from the point A by 2w in a direction transverse to the rotation direction of the tire, and a triangle formed by the point A, the point B, and the point C is selected. The area is repeatedly quadratured until any one of the points A, B, and C becomes the coordinate of all the coordinates of the light-section line, and the depth of the groove is calculated from the quadratured area of the triangle. 5. The apparatus for measuring the depth of the main groove in the rotational direction according to claim 4, further comprising means for measuring the depth of the main groove in the rotational direction.
  6. 前記ｗは前記回転方向主溝の幅以上であり、前記回転方向主溝の深さは、前記回転方向主溝に設けられているスリップサインの値以上であることを特徴とする請求項４又は５に記載の回転方向主溝深さの測定装置。

          5. The w is equal to or larger than the width of the main groove in the rotational direction, and the depth of the main groove in the rotational direction is equal to or larger than the value of the slip sign provided in the main groove in the rotational direction. 6. The apparatus for measuring the depth of the main groove in the rotational direction according to 5.
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