JP5714627B2 - Cylindrical inspection device - Google Patents

Description

  The present invention relates to a cylindrical body inspection apparatus for inspecting a cylindrical inspection object, particularly a semiconductor ingot for defects.

  A silicon wafer widely used as a material of a semiconductor element is cut out from a single crystal silicon ingot. A schematic diagram of the silicon ingot is shown in FIG. According to the Czochralski method (CZ method), in a crucible in which dissolved silicon is stored, a neck part having a diameter of several millimeters is formed by a seed crystal, and then the neck part is held and pulled up while rotating gently. A cylindrical silicon ingot that is a single crystal is produced (see FIG. 9). The silicon ingot that has been pulled up from the crucible (as grown) has a shape in which conical portions C are formed at both ends of the cylindrical portion S, as shown in FIG. Only the cylindrical portion S is usually processed into a silicon wafer.

  In the process of manufacturing the silicon ingot, crystal defects may occur in the silicon ingot. The crystal defects of the silicon ingot I often appear as flaws F running spirally on the outer surface of the silicon ingot I as shown in FIG. As shown in FIG. 9, the scratch F typically has a spiral shape inclined at about 45 degrees with respect to the circumferential direction, but may appear at an angle of about 30 to 60 degrees.

  If a portion having crystal defects in an ingot is processed into a wafer and discarded as a defect in the subsequent inspection, all processes for processing from the ingot to the wafer are wasted. Therefore, conventionally, a portion having a crystal defect is cut in advance from an ingot, and only a healthy portion is used for processing a wafer. That is, the healthy region shown in FIG. 9 has been cut in a cross section perpendicular to the central axis, and only this portion has been sent to a subsequent process and processed into a wafer. In this way, a good wafer can be cut out from an ingot having crystal defects, and the yield has been increased.

  The range of the defective area having crystal defects in the ingot was determined by the inspector viewing the cylindrical outer surface. Therefore, when the inspector overlooks the crystal defect, the portion having the crystal defect is processed into a wafer, and all the steps are wasted. On the other hand, when the inspector determines the range of crystal defects to be large with a margin, there is a problem that the range of the sound portion is reduced and the yield is deteriorated.

  As an ingot inspection device that does not rely on visual inspection, an inspection device that inspects defects inside the ingot by irradiating light on the ingot to detect scattered light or transmitted light is known (Patent Documents 1 and 2). reference). However, the inspection apparatuses described in Patent Documents 1 and 2 only detect the presence or absence of defects inside the ingot. Therefore, when a defect is detected, all the ingots are discarded, and a healthy portion cannot be taken out from the ingot, resulting in a very low yield.

  Therefore, there has been a demand for a semiconductor ingot inspection apparatus that can reliably detect a sound portion even in a defective ingot without reducing the yield.

JP 2012-93331 A JP 2004-279353 A

  Therefore, the problem to be solved by the present invention is to inspect a cylindrical inspection object such as an ingot, and to inspect the outer surface of the cylindrical object so that a healthy part without defects can be reliably detected. Is to provide a device.

The present invention has been made to solve the above-mentioned problems, and the invention according to claim 1 is directed to a rotating means for rotating a cylindrical inspection object around its central axis, and the rotating inspection object. an irradiation unit for irradiating light to the outer surface, and a light receiving portion for emitting a light reception signal by receiving the light reflected et al or the outer surface, on the basis of the light reception signal of the light receiving portion, the outer surface, the central axis An image obtained by dividing the two-dimensional image into a plurality of image elements in the central axis direction and the circumferential direction. A rectangular area in which the image element of the two-dimensional image is partitioned by the two straight lines in the circumferential direction, the sound area not including any defect, and the defective area including the defect that is the rectangular area a dividing means for dividing the two wards, prior to each of the image element The boundary between the healthy areas and the faulty areas, a cylindrical body inspection apparatus according to an outputting means for outputting the coordinate values of the center axis direction from the origin of the image elements.

  According to the invention described in claim 1, in the cylindrical inspection object, it is possible to reliably obtain a boundary between a healthy region that does not include a defect and a defective region that includes a defect, and by cutting the boundary, It is possible to provide a cylindrical body inspection apparatus that can reliably extract a healthy region.

In the invention according to claim 2, the image processing means generates a defect line segment on which the defect is displayed as a line segment on the two-dimensional image, and the segmenting means includes the circle in each image element. A pixel column arranged in the circumferential direction, the pixel column including at least part of the defective line segment is determined as a defective pixel column, and the defective pixel column continuous in the central axis direction is determined as the defective region. The cylindrical body inspection apparatus according to claim 1, wherein:

  According to the second aspect of the present invention, it is possible to provide a cylindrical body inspection apparatus capable of reliably determining a defective area by expressing a defect as a line segment.

The invention according to claim 3 is characterized in that the image processing means generates a defect line segment on which the defect is displayed as a line segment on the two-dimensional image, and the sorting means includes the defect in each image element. 2. A defect line segment region formed by projecting a line segment onto the coordinate axis in the central axis direction is generated, and a region connecting the overlapping defect line segment regions is determined as the defective region. It is a cylindrical body inspection apparatus as described in above.

  According to the third aspect of the present invention, the cylindrical body inspection capable of reliably and easily determining the defective area with a small amount of calculation by projecting the defect expressed as a line segment onto the coordinate axis in the central axis direction. An apparatus can be provided.

  According to a fourth aspect of the present invention, the irradiation unit irradiates the outer surface with linear laser light extending in the central axis direction, and the light receiving unit receives reflected light of the linear laser light. It is a line sensor, It is a cylindrical body inspection apparatus in any one of Claims 1-3 characterized by the above-mentioned.

  According to the fourth aspect of the present invention, it is possible to provide a cylindrical body inspection apparatus that can be configured at low cost by using a laser light source and a line sensor.

  The invention according to claim 5 is the cylindrical body inspection apparatus according to claim 4, wherein the irradiation section and the light receiving section are movable in the central axis direction.

  According to the fifth aspect of the present invention, it is possible to provide a cylindrical body inspection apparatus capable of inspecting even when the cylindrical body is longer than the irradiation range of the irradiation unit.

  The invention according to claim 6 further includes a mounting device for mounting the object to be inspected on the rotating means, and the mounting device grips the object to be inspected in a diameter direction and sets the diameter of the object to be inspected. The cylindrical body inspection apparatus according to claim 1, further comprising a gripping mechanism for measuring.

  According to the sixth aspect of the present invention, it is possible to mount the inspection object on the rotating means and to perform the cylindrical inspection capable of omitting the inspection of the inspection object that does not satisfy the quality standard of the diameter dimension. An apparatus can be provided.

  The invention according to claim 7 further comprises a length detection means for detecting the length of the inspection object in the central axis direction. The cylindrical body inspection according to any one of claims 1 to 3 Device.

  According to the seventh aspect of the present invention, it is possible to provide a cylindrical body inspection apparatus capable of omitting inspection of an inspection object that does not satisfy the quality standard for length dimensions.

  According to the present invention, in a cylindrical inspected object, a boundary between a healthy area that does not include a defect and a defective area that includes a defect can be reliably obtained, and the healthy area can be reliably obtained by cutting the boundary. A cylindrical body inspection apparatus that can be taken out can be provided.

It is a perspective view which shows the cylindrical body inspection apparatus which concerns on embodiment of this invention. It is a side view which shows the cylindrical body inspection apparatus which concerns on embodiment of this invention. It is explanatory drawing explaining the acquisition method of the image by the cylindrical body inspection apparatus which concerns on embodiment of this invention, (a) is a perspective view which shows operation | movement of the cylindrical body inspection apparatus at the time of acquiring an image element, (b) () Is a plan view showing an example of an image element acquired by the operation of (a). It is a figure which shows the two-dimensional image acquired by the cylindrical body inspection apparatus which concerns on embodiment of this invention, (a) is a perspective view explaining the divided | segmented image element, (b) is the image in a whole image It is a top view explaining arrangement | positioning of an element. It is a flowchart which shows the procedure of the process which the cylindrical body inspection apparatus which concerns on embodiment of this invention performs. It is a schematic diagram which shows an example of the method of classifying a healthy area | region and a defect area | region based on the two-dimensional image acquired using the cylindrical body inspection apparatus which concerns on embodiment of this invention. It is a flowchart which shows the method of classifying a healthy area | region and a defect area | region based on the defect line segment area | region which projected the defect line segment on a two-dimensional image on the coordinate axis of a central axis direction. It is a flowchart which shows the subroutine which integrates a defect line segment area | region among the flows shown in FIG. It is a figure which shows the crystal defect which appears as a spiral flaw on the outer surface of a semiconductor ingot.

  Next, embodiments of the present invention will be described with reference to the drawings. The embodiments described below are preferred embodiments of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention is particularly limited in the following description. As long as there is no description of the effect, it is not restricted to these aspects.

(Configuration of cylindrical body inspection device)
The configuration of the embodiment of the cylindrical body inspection apparatus according to the present invention will be described with reference to FIGS. FIG. 1 is a perspective view showing a cylindrical body inspection apparatus according to this embodiment, and FIG. 2 is a side view showing the cylindrical body inspection apparatus according to this embodiment.

  The cylindrical body inspection apparatus 100 according to the present embodiment includes the rotation unit 10, the irradiation unit 20, the light receiving unit 30, the axial movement device 40, the mounting device 50, and the controller 60 as main components. In this embodiment, the cylindrical body inspection apparatus 100 divides and acquires a two-dimensional image obtained by imaging the shape change of the outer surface of the ingot I set as shown in FIG. 1, and the acquired two-dimensional image By performing image processing, the boundary position between the healthy area and the defective area of the ingot I is output.

  The rotating means 10 is configured to rotate the ingot I about its central axis. The rotating means 10 includes a roller 11 on which the ingot I is placed, and a rotation driving unit 12 that rotationally drives the roller 11. When the rotation drive unit 12 rotates the roller 11, the ingot I rotates around its central axis. While the ingot I rotates, the light receiving unit 30 described later acquires a two-dimensional image of the outer surface of the cylindrical portion S of the ingot I along the circumferential direction. In the present embodiment, the two-dimensional image of the outer surface of the cylindrical portion S of the ingot I is configured to rotate at a predetermined angular pitch so as to be acquired in the circumferential direction. And it is comprised so that it can cover for one round about the circumferential direction by repeating rotation with a predetermined angle pitch. In the present embodiment, it is divided into four in the circumferential direction and is rotated at a pitch of 90 degrees. Details will be described later.

  The ingot I can be supported by providing an air cylinder or the like on the rotating means 10.

  The irradiation unit 20 is configured to irradiate the outer surface of the cylindrical portion S of the ingot I with the laser beam B. The laser beam B irradiated by the irradiation unit 20 is a laser beam that scans in a line in the central axis direction of the ingot I. The laser beam B is irradiated toward the ingot I as a laser beam scanned in a line by reflecting spot light from a laser light source to a polygon mirror rotating at high speed.

  The light receiving unit 30 is configured such that the laser beam B emitted from the irradiation unit 20 hits the outer surface of the cylindrical portion S of the ingot I and receives the reflected light R reflected from the outer surface. It consists of a line sensor consisting of an optical fiber and a light intensity detector. The light receiving unit 30 emits a light reception signal corresponding to the amount of light received and sends it to the controller 60 described later. The light receiving unit 30 is configured to receive reflected light R reflected from a one-dimensional region W (see FIG. 3A) extending in the central axis direction on the outer surface of the cylindrical portion S of the ingot I. The irradiation unit 20 and the light receiving unit 30 are configured to be movable in the central axis direction of the ingot I by an axial movement device 40 described later.

  The light received by the light receiving unit 30 is recorded as a digital image that is an aggregate of pixels. A two-dimensional image of the entire outer surface of the cylindrical portion S of the ingot I is recorded by being divided into a plurality of image elements.

  The axial movement device 40 is configured to move the irradiation unit 20 and the light receiving unit 30 in the central axis direction of the ingot I. Specifically, the axial movement device 40 includes an axial movement body 41 and a rail 42, and the axial movement body 41 is movable on a rail 42 extending in the central axis direction of the ingot I. It is configured. An irradiation unit 20 and a light receiving unit 30 are installed on the axially moving body 41. The axial direction moving body 41 is controlled so as to repeat movement at a predetermined pitch. The movement pitch is determined by the length of the one-dimensional region W that the light receiving unit 30 can receive. By such a moving method, a two-dimensional image can be acquired without omission about the entire length of the cylindrical portion S of the ingot I.

  In addition, it is suitable to provide the adjustment mechanism which can adjust the direction of the irradiation part 20 and the light-receiving part 30 in the axial direction moving body 41 in which the irradiation part 20 and the light-receiving part 30 are installed. The directions of the irradiation unit 20 and the light receiving unit 30 are adjusted according to the shape of the cylindrical portion S of the ingot I to be inspected. The cylindrical portion S of the ingot I is not necessarily a complete cylindrical body and may be slightly tapered, but this is because the light receiving unit 30 can reliably receive the reflected light R even in such a case.

  The mounting device 50 is configured to hold the ingot I and to place the ingot I on the rotating means 10. Specifically, the mounting device 50 includes a gripping mechanism 51 having a gripping claw 51 a and a claw driving unit 51 b, a gripping part translation mechanism 52 that moves the gripping mechanism 51 in a horizontal plane perpendicular to the rotation axis of the rotating means 10, and gripping A gripper rotation mechanism 53 is provided that rotates the entire mechanism 51 around an axis parallel to the rotation axis of the rotation means 10. The mounting device 50 is configured to be suitable for gripping the ingot I conveyed away from the rotation axis of the rotating means 10 and mounting it on the rotating means 10.

  The gripping claw 51a of the gripping mechanism 51 grips the ingot I by sandwiching the ingot I up and down in the radial direction. The claw driving unit 51b drives the gripping claws 51a so as to narrow the interval between the upper and lower gripping claws 51a. After the gripping mechanism 51 grips the ingot I transported away from the rotation shaft of the rotating means 10, the gripper translation mechanism 52 operates to bring the gripping mechanism 51 closer to the rotating means 10 in the same posture. Then, after the gripping mechanism 51 is sufficiently close to the rotating means 10, the gripping part rotating mechanism 53 rotates the entire gripping mechanism 51 by 180 degrees to place the ingot I at the position shown in FIG. 1 of the rotating means 10.

  The gripping mechanism 51 of the mounting device 50 is configured to be able to measure the diameter of the ingot I by gripping the ingot I. If the diameter of the ingot I is not within the specified range, the inspection of the defect of the ingot I may be omitted.

  Further, the mounting device 50 can be configured to measure the length of the ingot I. This can be achieved by providing a plurality of proximity sensors spaced apart in the central axis direction of the ingot I as length detection means. That is, when both of the two proximity sensors that are separated detect the proximity of the ingot I, it indicates that the ingot I has a length that is greater than or equal to the distance between the two proximity sensors, and only one of them is the ingot I. , The ingot I indicates that the distance between the two proximity sensors is shorter. If three or more proximity sensors are used, the length can be measured more finely. If the length of the ingot I is not within the specified range, the inspection of the defect of the ingot I may be omitted.

  The mounting device 50 for mounting the ingot I on the rotating means 10 is not an essential device for the cylindrical body inspection device 100, and is configured to mount the ingot I on the rotating means 10 by human power instead of the mounting device 50. Of course it is possible.

  The controller 60 controls the entire cylindrical body inspection apparatus 100. And a digital image is produced | generated based on the light reception signal from the light-receiving part 30, and the image process which sharpens a defect regarding the image is performed. Then, the sound area and the defective area are determined based on the image, and the boundary between the sound area and the defective area is output. This output can be performed on any medium such as display on a display, printing on paper, storage in a flash memory, or output to another computer via a network.

  Next, an image acquired by the cylindrical body inspection apparatus 100 according to the present embodiment will be described with reference to FIGS. FIG. 3 is an explanatory diagram for explaining an image acquisition method by the cylindrical body inspection apparatus according to the present embodiment, and (a) is a perspective view illustrating an operation of the cylindrical body inspection apparatus when acquiring an image element. (B) is a top view which shows the example of the image element acquired by the operation | movement of (a). 4A and 4B are diagrams illustrating a two-dimensional image acquired by the cylindrical body inspection apparatus. FIG. 4A is a perspective view illustrating divided image elements, and FIG. 4B is an arrangement of image elements in the entire image. FIG.

  After the ingot I is placed on the rotating means 10, the irradiation unit 20 faces the outer surface of the cylindrical portion S of the ingot I with a predetermined length in the central axis direction of the ingot I while rotating the ingot I at a predetermined angle. A linear laser beam B having a thickness is irradiated, and the light receiving unit 30 receives the reflected light R from the irradiated region W (see FIG. 3A). Thereby, the digital image element g in which the unevenness of the outer surface of the ingot I is imaged as light and dark is obtained (see FIG. 3B). Note that the horizontal width of the image element g shown in FIG. 3B is the length of the region W, and the vertical height is the circumferential length that moves when the ingot I rotates by a predetermined angle. Since the crystal defect of the ingot I appears as minute irregularities on the outer surface, the crystal defect appears in the image element g as a defect line segment F in which a bright part or a dark part extends linearly. Note that the image element g is obtained by developing a cylindrical outer surface into a plane, and a spiral defect on the outer surface appears as a line segment inclined at a certain angle (for example, 45 degrees) in the image element g. In the present embodiment, image processing is performed for each image element g, and defects existing in the image element g are recognized.

  A two-dimensional image of the outer surface of the cylindrical portion S of the ingot I is acquired by being divided into a plurality of image elements g as shown in FIG. In the present embodiment, as shown in FIG. 4A, the outer surface of the cylindrical portion S of the ingot I is divided into four in the circumferential direction and seven in the central axis direction, and a total of 28 image elements g11. ,..., G74. The numbers given to the image elements g are numbered as g11, g12,..., G14 along the circumferential direction from the origin O, and g11, g21,. ... numbering like g71.

  FIG. 4B shows an entire image G that represents the entire outer surface of the cylindrical portion S of the ingot I from the image elements g11,..., G74. By arranging all the acquired image elements g, the entire outer surface is expressed as a whole image G. In FIG. 4B, the entire image G is configured by arranging the image elements g without gaps. However, the entire image G can also be configured by acquiring the image elements g so as to have overlapping portions. It is.

  In this embodiment, the image element is divided into a total of 28 image elements, which are divided into four parts in the circumferential direction and seven parts in the central axis direction. However, the number of divisions can be arbitrarily set. For example, it is possible to acquire an image of 360 degrees without being divided in the circumferential direction. As for the number of divisions in the central axis direction, it is possible to reduce the number of divisions by setting the length of the region W irradiated with the laser beam B longer.

(Processing flow)
Next, a procedure of processing performed by the cylindrical body inspection apparatus according to the present embodiment will be described with reference to FIG. FIG. 5 is a flowchart showing a procedure of processing performed by the cylindrical body inspection apparatus. Note that the flowchart shown in FIG. 5 starts from a state in which the mounting apparatus 50 grips the ingot I.

  In step S11, the diameter of the ingot I is measured. As described above, the diameter of the ingot I is measured by the gripping claws 51a of the gripping mechanism 51 sandwiching the ingot I in the radial direction. If the measured diameter is within the predetermined range, the process proceeds to the next step S12. If the diameter is not within the predetermined range, the ingot I is determined to be defective in dimension, and the process ends without inspecting the defect.

  In step S12, the length of the ingot I is measured. As described above, the length of the ingot I is measured by a plurality of proximity sensors provided in the cylindrical body inspection apparatus 100 as length detection means. If the measured length is within the predetermined range, the process proceeds to the next step S13. If the diameter is not within the predetermined range, the ingot I is determined to be defective in dimension, and the process ends without inspecting the defect. If the length of the ingot I is within a predetermined range, the ingot I can be supported, but if it is not within the predetermined range, the ingot I cannot be set on the rotating means 10.

  In step S <b> 13, the gripped ingot I is mounted on the rotating means 10. In order to mount the ingot I, the gripper translation mechanism 52 of the mounting device 50 is first moved closer to the rotating means 10, and then the gripper claw 51 a is moved 180 from the position shown in FIG. 1 by the operation of the gripper rotation mechanism 53. And the ingot I is placed on the rotating means 10. Then, after placing the ingot I on the rotating means 10, the gripping mechanism 51 returns to its original position.

  In step S14, the origin O of the ingot I is set. The origin O is given by marking the reference position on the ingot I in advance. In the present embodiment, a connecting portion between the conical portion C and the cylindrical portion S of the ingot I in the central axis direction, and an arbitrary position is set as the origin O in the circumferential direction.

  In step S15, the position of the axial movement device 40 is initialized. Specifically, the axial direction is such that one end W1 (see FIG. 3A) of the region W irradiated with the laser beam B is positioned on a circumference V1 (see FIG. 4A) passing through the origin O. The moving body 41 is moved in the central axis direction of the ingot I. This makes it possible to acquire image elements in order from the circumference V1 side.

  In step S16, the circumferential position is initialized. Specifically, the reflected light R reflected from the region of the straight line H (see FIG. 4A) passing through the origin O and parallel to the central axis is received by the light receiving unit 30 (that is, FIG. 3A). Rotating means 10 is rotated so that the region W of (1) is on the straight line H in FIG. This makes it possible to acquire image elements in order from the straight line H side. In addition, since any position in the circumferential direction can be set as the origin O as described above, in the present embodiment, a linear region where the ingot I is mounted and which emits the reflected light received by the light receiving unit 30 is a straight line H. The intersection of the straight line H and the circumference V is defined as the origin O.

  In step S17, it is determined whether or not the ingot I has made one rotation after the circumferential position is initialized. That is, the determination of one rotation is performed when the value of the encoder that detects the number of rotations of the rotation driving unit 12 reaches a value corresponding to one rotation calculated from the diameter of the ingot I and the diameter of the roller 11. If it is not determined that the ingot I has made one revolution, the process proceeds to step S18. If it is determined that the ingot I has made one revolution, the process proceeds to step S20.

  In step S <b> 18, the reflected light R is received by the light receiving unit 30 while rotating the ingot I by a predetermined angle using the rotating unit 10, and the image element g is acquired. Next, in step S19, a healthy area and a defective area in the range of the ingot I corresponding to the image element g are determined from the obtained image element g, and a boundary between the healthy area and the defective area is detected. A method for determining the healthy area and the defective area will be described later. Note that image processing for clarifying the defect line segment F appearing in the acquired image element g is appropriately performed before determining the healthy area and the defective area. The controller 60 performs the determination of the healthy area and the defective area and the image processing prior to the determination.

  And it progresses to determination of step S17 again. Through the loop of steps S17 to S19, image elements for one round at a predetermined position in the central axis direction are acquired, and the boundary between the healthy area and the defective area in the range of the ingot I corresponding to the acquired image element is output. The In the present embodiment, as shown in FIG. 4, the loop of steps S17 to S19 is repeated four times at 90 ° intervals. Note that this loop of steps S17 to S19 rotates 360 ° without stopping the rotation of the ingot I halfway, and stores the image element acquired every 90 ° rotation in the storage means for image processing and boundary detection. It is also possible to configure the operations to be performed in parallel.

  In Step S20, it is determined whether the irradiation unit 20 and the light receiving unit 30 have reached the end of the ingot I in the central axis direction. That is, it is determined whether the other end W2 (see FIG. 3A) of the region W irradiated with the laser beam B has reached the circumference V2 (see FIG. 4A) at the end of the cylindrical portion S of the ingot I. judge. When it is not determined that the end in the central axis direction has been reached, the process proceeds to step S21, and when it is determined that the terminal has reached, the process proceeds to step S22.

  In step S21, the axial moving body 41 is moved by a predetermined distance in the central axis direction. This moving distance is set to a distance equal to or shorter than the length of the region W irradiated with the laser beam B. Thereby, the cylindrical part S of the ingot I is acquired without a gap in the central axis direction, and the entire cylindrical part S is covered with a plurality of image elements g. After step S21 is completed, the process returns to step S16.

  In step S22, the detection results of the boundary between the healthy area and the defective area in each image element obtained by repeating the loop of steps S16 to S21 are integrated, and the healthy area and the defective area in the entire cylindrical portion S of the ingot I are integrated. Output the boundary with the region. That is, in the present embodiment, as shown in FIG. 4, the loop from step S16 to S20 is repeated seven times, and the boundary between the healthy area and the defective area obtained for each of the total 28 image elements g is determined in step S22. Integrated. Then, the process proceeds to step S23.

  In step S <b> 23, the ingot I is lowered from the rotating means 10 using the mounting device 50. In this way, all processing is completed. This process flow is also controlled by the controller 60.

(Judgment of boundary between healthy area and defective area)
Next, a method for determining a healthy area and a defective area from the acquired image element g will be described with reference to FIGS. FIG. 6 is a schematic diagram illustrating an example of a method for classifying a healthy area and a defective area based on the acquired image element g. FIGS. 7 and 8 are flowcharts for explaining another example of a method for classifying a healthy area and a defective area based on an acquired image element g.

  FIG. 6 shows an image element g. The image element g is a digital image in which a part of the cylindrical portion S of the ingot I is developed on a plane. The horizontal axis indicates the central axis direction of the ingot I, and the vertical axis indicates the circumferential direction of the ingot I. In the image element g, defect line segments F1, F2, F3, and F4 appearing in a certain angle (for example, 45 degrees) direction appear. The range of the image element g extends from the origin o defined for each image element g to Xr in the horizontal axis direction and Yr in the vertical axis direction.

  A method for determining a healthy area and a defective area based on the image element g is as follows. That is, for a pixel row arranged in the circumferential direction at a certain central axis coordinate position, if the pixel row intersects any one of the defect line segments F, pixels arranged in the circumferential direction at the central axis coordinate position The column is determined as a “defective pixel column”. If defective pixel rows are continuously arranged in the central axis direction, it becomes a defective area. On the other hand, a pixel column that does not intersect any of the defective line segments F is a “non-defective pixel column”, and if the non-defective pixel column is continuously arranged in the central axis direction, it becomes a healthy region. . By repeating the above determination for all the pixel columns arranged in the central axis direction, a healthy area and a defective area are classified. The healthy area and the defective area appear in the image element g as a rectangular area having a vertical axis length as one side. In FIG. 6, the image element g is divided into two healthy regions and two defective regions. Then, the central axis direction (x) coordinate value of the boundary between the healthy area and the defective area is determined. In FIG. 6, coordinate values x1, x2, and x3 in the central axis direction are output as boundary positions. When the controller 60 outputs this coordinate value, the position where the ingot I is to be cut is recognized in a subsequent process.

  Instead of outputting the boundary position between the actual healthy area and the defective area, it is also possible to output the boundary position by setting the range of the defective area wider than the actual range. It is also possible to provide an appropriate threshold value and to consider a healthy area in a section shorter than the threshold value as a defective area. By doing so, it is possible to prevent the sound region having a very narrow range, that is, the short cylindrical sound portion having a very low height, from being cut into pieces.

  Another example of a method for classifying the healthy area and the defective area based on the acquired image element g will be described with reference to FIGS. FIG. 7 is a flowchart showing a method for classifying a healthy area and a defective area based on a defect line area obtained by projecting a defect line segment on a two-dimensional image onto a coordinate axis in the central axis direction, and FIG. Is a flowchart showing a subroutine for integrating defect line segment areas. The method represented by the flowcharts of FIGS. 7 and 8 includes a method in which when a plurality of defect line segments are overlapped in one area, these are integrated and set.

  It is assumed that P defect line segments F are detected from the acquired image element g by image processing. A healthy area and a defective area are determined in consideration of only the x-coordinates of the start point and end point of each defect line segment F. The flowchart of FIG. 7 starts from a state in which the above-described P defect line segments F are obtained. Note that a defect line segment F in consideration of only the x coordinate, that is, a region in which the defect line segment F is projected on the x-axis is hereinafter referred to as a defect line segment region L.

  In step S101, it is determined whether or not a defect line segment F exists, specifically, whether or not P ≠ 0. If the defective line segment F exists, that is, if P ≠ 0, the process proceeds to step S102. If the defective line segment F does not exist, that is, if P = 0, the process proceeds to step S109, and the entire area is set as a healthy area and the process ends.

  In step S102, P defect line segments F are arranged in ascending order of the start point coordinates, and each defect line segment is numbered as F1, F2,..., Fi,. Then, the process proceeds to step S103. If the x coordinate of the start point of the i-th defect line segment Fi is Xis and the x coordinate of the end point is Xie, the start point coordinate of the defect line segment region Li is Xis and the end point coordinate is Xie.

  In step 103, it is determined whether or not the x coordinate X1s of the starting point of the defect line segment F1 does not coincide with the position of the origin o. If they do not match, the process proceeds to step S104, and if they do not match, the process proceeds to step S105. In step S104, the region from the origin o to the start point coordinate X1s of the defect line segment F1 is set as a healthy region. This is because the defect line segment F does not exist at all in this region, so that it is determined as a healthy region. Next, the process proceeds to step S105. Even when the distance from the origin o to X1s is shorter than the above-described threshold value for considering the healthy area in the short section as a defective area, the process proceeds to the next step S105 without setting the healthy area.

  In step S105, first, the defect line segment region L1 is set as a reference region. This is because the defective area is determined by integrating the overlapping defect line segment areas by comparing the reference area and the other defect line segment areas Li, thereby distinguishing the healthy area from the defective area. The reference area is defined by the start point coordinate Xs and the end point coordinate Xe. Next, the process proceeds to step S106.

  In step S106, the defect line segment integration subroutine is repeated in a loop of j = 2 to P. The defect line segment integration subroutine of step S106 is a subroutine that compares the reference area and the inspection area (defect line segment area L), detects the overlap of the areas, and integrates them as defective areas.

  Next, details of the defect line segment integration subroutine in step S106 will be described with reference to FIG. When the defect line segment integration subroutine is started, the j-th defect line segment area Lj is set as an inspection area. In step S111, it is determined whether or not the inspection area is included in the reference area. Specifically, the end point Xje of the inspection area is compared with the end point Xe of the reference area, and when Xje ≦ Xe, as shown in the schematic diagram M1, it is determined that the inspection area is included in the reference area, and the subroutine ends. To do. Otherwise, the process proceeds to step S112.

  In step S112, it is determined whether or not the inspection area partially overlaps the reference area. Specifically, the start point Xjs of the inspection area is compared with the end point Xe of the reference area. If Xjs ≦ Xe, it is determined that the inspection area partially overlaps the reference area as shown in the schematic diagram M2. The process proceeds to step S113. Otherwise, as shown in the schematic diagram M3, it is determined that the inspection area is separated from the reference area, and the process proceeds to step S114.

  The reference area and the inspection area are both one-dimensional areas and exist on one axis. In the schematic diagrams M1 to M3 in FIG. The reference area and the inspection area are drawn separately above and below.

  In step S113, the inspection area is integrated with the reference area, and the reference area is extended. Specifically, the end point Xje of the inspection region is substituted for the end point Xe of the reference region. Then, this subroutine ends.

  In step S114, since the inspection area is separated from the reference area, the area from the end point Xe of the reference area to the start point Xjs of the inspection area is set as a healthy area. However, when the distance from Xe to Xjs is shorter than the above-described threshold value for considering a healthy area in a short section as a defective area, it is not set as a healthy area. In step S115, the inspection area is newly set as a reference area (that is, Xjs is assigned to Xs and Xje is assigned to Xe), and the subroutine ends.

  Note that the reference area set in steps S113 and S115 is compared with the next inspection area (j + 1-th defect line area L) in the next defect line area integration subroutine, and the overlap of the areas is detected. Will be integrated.

  When the loop of step S106 in FIG. 7 is completed, the last defect line segment area (Xs to Xe) is determined. Next, the process proceeds to step S107.

  In step 107, it is determined whether or not the end point coordinate Xe of the last defective line segment region is inconsistent with the end point Xr of the x coordinate of the image element g. If they do not match, the process proceeds to step S108, and if they do not match, the process ends. In step S108, a sound region is set from the end point coordinate Xe of the last defect line segment region to the end point Xr of the x coordinate of the image element g. Note that, even when the distance from Xe to Xr is shorter than the above-described threshold value for considering the healthy area of the short section as a defective area, the process is terminated without setting the healthy area.

  In this way, the healthy area of the entire area is determined, and the defective area is determined by excluding the determined healthy area from the entire area. And it becomes possible to output the boundary between a healthy area and a defective area.

  In the above-described embodiment, the configuration in which the boundary between the healthy region and the defective region is output for each image element g has been described. However, the entire outer surface of the cylindrical portion S of the ingot I is integrated by integrating the individual image elements. Of course, it is possible to output the boundary between the healthy area and the defective area after the image G is constructed.

DESCRIPTION OF SYMBOLS 100 Cylindrical body inspection apparatus 10 Rotating means 20 Irradiation part 30 Light receiving part 50 Mounting apparatus 51 Grasp mechanism 60 Controller B Laser beam R Reflected light G Whole image g Image element F Defect line segment L Defect line segment area

Claims (7)

Rotating means for rotating a cylindrical inspection object around its central axis;
An irradiation unit for irradiating light to the outer surface of the rotating inspection object;
A light receiving section for emitting the received light signal by receiving the light reflected et al or the outer surface,
Based on the light reception signal of the light receiving unit, the outer surface is expressed as a two-dimensional image divided into pixels with a central axis direction and a circumferential direction as two coordinate axes, and the two-dimensional image is expressed as the central axis. Image processing means for dividing and obtaining a plurality of image elements in the direction and the circumferential direction ;
A rectangular area obtained by dividing each image element of the two-dimensional image by the two straight lines in the circumferential direction, which is divided into a healthy area that does not include any defect and a defective area that includes the defect and includes the rectangular area. A sorting means,
A cylindrical body inspection apparatus comprising: an output unit that outputs a coordinate value in a direction of the central axis from the origin of the image element at the boundary between the healthy area and the defective area for each image element . The image processing means generates a defect line segment on which the defect is displayed as a line segment on the two-dimensional image,
In the image elements, the sorting means
A pixel column arranged in the circumferential direction, and a pixel column including at least part of the defective line segment is determined as a defective pixel column;
The cylindrical body inspection apparatus according to claim 1, wherein the defective pixel row continuous in the central axis direction is determined as the defective area. The image processing means generates a defect line segment on which the defect is displayed as a line segment on the two-dimensional image,
In the image elements, the sorting means
While generating a defect line segment region formed by projecting the defect line segment on the coordinate axis in the central axis direction,
The cylindrical body inspection apparatus according to claim 1, wherein an area in which the overlapping defect line segment areas are connected is determined as the defective area. The irradiation unit irradiates the outer surface with linear laser light extending in the central axis direction;
The cylindrical body inspection device according to claim 1, wherein the light receiving unit is a line sensor that receives reflected light of the linear laser beam. The cylindrical body inspection apparatus according to claim 4, wherein the irradiation unit and the light receiving unit are movable in the direction of the central axis. A mounting device for mounting the inspection object on the rotating means;
The cylindrical mounting apparatus according to claim 1, wherein the mounting apparatus includes a gripping mechanism that grips the object to be inspected in a diameter direction and measures the diameter of the object to be inspected. . The cylindrical body inspection apparatus according to claim 1, further comprising a length detection unit that detects a length of the inspection object in the central axis direction.

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