Pipe symbol reading device and pipe symbol reading method

Abstract

To realize a pipe symbol reading device and pipe symbol reading method that can read uneven symbols formed on an outer surface of a pipe with high accuracy and can shorten the time required to read the uneven symbols.SOLUTION: A symbol reading device 1 includes: a three-dimensional data acquisition unit 10 configured to acquire three-dimensional data of uneven symbols 90 by measuring the height of the uneven symbols 90 relative to an outer surface 99a of a pipe 99 while rotating the pipe 99 relatively around an axis P; an image data conversion unit 40 configured to convert the acquired three-dimensional data into image data 41 in which the uneven symbols 90 are arranged in a straight line; a reference symbol identification unit 50 configured to identify a reference symbol 51 that serves as a reference for starting reading an uneven symbol image portion 49, which is image data of the uneven symbol 90 in the image data 41; and a symbol reading unit 60 configured to use the image data 41 to read a reading object portion 61 in the uneven symbol image portion 49 with reference to the reference symbol 51.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a pipe symbol reading device and a pipe symbol reading method for reading a rugged symbol formed on the outer surface of a pipe by recesses or protrusions aligned in one circumferential direction. [Background technology]

[0002] For example, in cast iron pipes (one example of water pipes) used for water supply, symbols including letters, figures, etc. are formed in an uneven manner by concave or convex parts on the end face or flange face of the pipe. The symbols indicate predetermined pipe type, nominal diameter, manufacturing plant, manufacturing year, lot number, manufacturer, individual pipe identification number, etc.

[0003] As described above, a character reading device that reads characters formed in a concave-convex shape on a flange surface is known. For example, Patent Document 1 discloses a character reading device that reads characters formed by the concave-convex shape by rotating a pipe in a certain direction around its axis, measuring the pipe surface by a light-section method, and acquiring a two-dimensional processed image from profile data of the height of the concave-convex shapes on the measured pipe surface. This makes it possible to read characters formed by the concave-convex shapes, which are difficult to read with a CCD camera or the like due to reflected light. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6415164 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, the character reading device disclosed in Patent Document 1 continues to acquire the profile data for one revolution of the end face of the pipe, and ends acquiring the profile data when a blank area whose circumferential length is equal to or greater than a predetermined width is detected. Therefore, the character reading device disclosed in Patent Document 1 needs to specify the blank area in order to end acquisition of the profile data and identify characters (relief symbols) formed by recesses and projections.

[0006] However, for example, when the nominal diameter of the pipe is relatively small and the embossed symbols are densely formed around the entire circumference of the end face of the pipe, or when the embossed symbols are evenly spaced around the entire circumference of the end face of the pipe, the circumferential length of the blank area may be less than the predetermined width. In this case, the character reading device disclosed in Patent Document 1 may not be able to identify the blank area. As a result, when the profile data is obtained using the character reading device disclosed in Patent Document 1, the end point of data acquisition may be unclear.

[0007] As described above, if the blank area cannot be identified on the outer surface of the pipe, data acquisition may continue unnecessarily, lengthening the time it takes to read the embossed symbol, or profile data of the embossed symbol formed on the end face of the pipe may not be acquired with high accuracy.

[0008] Therefore, in a symbol reading device for reading the embossed symbol formed on the outer surface of a pipe, it is desirable to read the embossed symbol more accurately and in a shorter time.

[0009] An object of the present invention is to provide a pipe symbol reading device and a pipe symbol reading method that can accurately read the embossed symbol formed on the outer surface of a pipe and can shorten the time it takes to read the embossed symbol. [Means for solving the problem]

[0010] A pipe symbol reading device according to one embodiment of the present invention is a symbol reading device that reads a rugged symbol formed on the outer surface of a pipe by recesses or protrusions aligned in one circumferential direction. This device has a three-dimensional data acquisition unit that acquires three-dimensional data of the rugged symbol by measuring the height of the rugged symbol relative to the outer surface of the pipe while rotating the pipe relatively around its axis, an image data conversion unit that converts the acquired three-dimensional data into image data in which the rugged symbols are aligned in a straight line, a reference symbol identification unit that identifies a reference symbol in the image data that serves as a reference for starting to read the rugged symbol, and a symbol reading unit that uses the image data to read the rugged symbol based on the reference symbol (first configuration).

[0011] According to the above-mentioned configuration, the three-dimensional data of the embossed symbols arranged in the circumferential direction on the outer circumferential surface of the pipe is acquired by the three-dimensional data acquisition unit, and image data in which the embossed symbols are arranged in a straight line can be obtained from the three-dimensional data. Then, by specifying a reference symbol that serves as a reference for starting to read the embossed symbols in the image data, the embossed symbols can be read using the reference symbol as a reference.

[0012] This allows the embossed symbol to be read using the reference symbol as a reference, so that the embossed symbol can be read more accurately from the image data. Moreover, even if the blank area disclosed in Patent Document 1 cannot be identified, the acquisition of the three-dimensional data is not continued by identifying the reference symbol in the image data converted from the three-dimensional data. Therefore, the reading time of the embossed symbol is not unnecessarily extended, and the embossed symbol can be read in a shorter time.

[0013] Therefore, by using a symbol reading device having the above-mentioned configuration, it is possible to read the embossed symbol formed on the outer surface of a pipe with higher accuracy and to shorten the time required to read the embossed symbol.

[0014] In the first configuration, the three-dimensional data acquisition unit acquires three-dimensional data of the uneven symbols while relatively rotating the tube in a direction opposite to the one direction in which the uneven symbols are arranged (second configuration).

[0015] This allows the three-dimensional data acquisition unit to acquire the three-dimensional data of the embossed symbol in one direction, which is the arrangement direction of the embossed symbol, and therefore allows the embossed symbol to be read more quickly and reliably.

[0016] In the first configuration, the symbol reading unit uses the image data to read a rugged symbol located behind the reference symbol in the one direction that is an arrangement direction of the rugged symbols (third configuration).

[0017] This allows the symbol reading unit to use the image data to read the embossed symbol located behind the reference symbol in one direction, which is the arrangement direction of the embossed symbols, and therefore allows the embossed symbol to be read more reliably.

[0018] In the first configuration, the three-dimensional data acquisition unit acquires three-dimensional data of the embossed symbol while rotating the pipe about the axis line by one or more revolutions relative to the pipe. The symbol reading unit uses the image data to read the embossed symbol located at a predetermined position in a direction opposite to the one direction in which the embossed symbols are arranged with respect to the reference symbol (fourth configuration).

[0019] As a result, even if the reference symbol is erroneously determined to be another symbol in the image data obtained from the three-dimensional data acquired while the tube is rotating one or more revolutions around its axis, the embossed symbol can be read more reliably by reading the embossed symbol located at a predetermined position in the opposite direction to the one direction in which the embossed symbols are arranged relative to the reference symbol subsequently identified by the reference symbol identification unit.

[0020] In the first configuration, the three-dimensional data acquisition unit divides the three-dimensional data into a predetermined data length and outputs the divided three-dimensional data. The image data conversion unit connects a plurality of the divided three-dimensional data to convert the data into the image data (fifth configuration).

[0021] This makes it possible to reduce the volume of data output from the three-dimensional data acquisition unit, thereby reducing the load on the symbol reading device.

[0022] In the first configuration, the symbol reading unit has a data extraction unit that extracts a predetermined range of image data at a predetermined position in the arrangement direction of the embossed symbol from the reference symbol in the image data, and a reading execution unit that reads the embossed symbol using image data of the range extracted by the data extraction unit (sixth configuration).

[0023] This makes it possible to reduce the volume of image data required when reading a embossed symbol, thereby reducing the load on a symbol reading device when reading a embossed symbol from image data.

[0024] Moreover, since image data of a predetermined range in which a embossed symbol is to be read can be extracted from the image data, it is possible to prevent image data outside the predetermined range from being read by mistake, and therefore it is possible to read the embossed symbol to be read from the image data with higher accuracy.

[0025] In the first configuration, the pipe symbol reading device further includes an image data filter unit that removes specific symbol data from the image data and generates image data for reading the embossed symbol by the symbol reading unit (seventh configuration).

[0026] This makes it possible to read the embossed symbol by removing specific symbol data from the image data. Therefore, it is possible to read only the necessary symbols from the image data with high accuracy. Therefore, it is possible to read the embossed symbol formed on the outer surface of the pipe with high accuracy.

[0027] In the first configuration, the three-dimensional data acquisition unit acquires three-dimensional data in which the inner wall and the outer wall of the pipe each become the contour of the area in which the embossed symbol is read. The image data conversion unit converts the contour in the image data into a straight line portion that can distinguish the area from the outside of the area (eighth configuration).

[0028] This makes it possible to clearly distinguish between the embossed symbol and the outline in the image data. Therefore, when reading the embossed symbol using the image data, it is possible to prevent the outline from being mistakenly read as part of the embossed symbol. Therefore, the embossed symbol can be read with higher accuracy.

[0029] A pipe symbol reading method according to one embodiment of the present invention is a symbol reading method for reading a rugged symbol formed on the outer surface of a pipe by recesses or protrusions aligned in one circumferential direction. This method includes a three-dimensional data acquisition step for acquiring three-dimensional data of the rugged symbol by measuring the height of the rugged symbol relative to the outer surface of the pipe while rotating the pipe relatively around its axis, an image data conversion step for converting the three-dimensional data acquired in the three-dimensional data acquisition step into image data in which the rugged symbols are aligned in a straight line, a reference symbol identification step for identifying a reference symbol serving as a reference for starting reading of the rugged symbol in the image data converted in the image data conversion step, and a symbol reading step for reading the rugged symbol based on the reference symbol identified in the reference symbol identification step using the image data (first method).

[0030] According to the above-mentioned method, the three-dimensional data of the embossed symbols arranged in the circumferential direction on the outer peripheral surface of the pipe is acquired in the three-dimensional data acquisition step, and image data in which the embossed symbols are arranged in a straight line can be obtained from the three-dimensional data. Then, by identifying a reference symbol that serves as a reference for starting to read the embossed symbols in the image data, the embossed symbols can be read based on the reference symbol.

[0031] This allows the embossed symbol to be read using the reference symbol as a reference, so that the embossed symbol can be read more accurately from the image data. Moreover, even if the blank area disclosed in Patent Document 1 cannot be identified, the acquisition of the three-dimensional data is not continued by identifying the reference symbol in the image data converted from the three-dimensional data. Therefore, the reading time of the embossed symbol is not unnecessarily extended, and the embossed symbol can be read in a shorter time.

[0032] Therefore, the above-mentioned symbol reading method can read the embossed symbol formed on the outer surface of the pipe with higher accuracy and can shorten the time required to read the embossed symbol.

[0033] In the first method, the pipe symbol reading method further includes a divided three-dimensional data generating step of dividing the three-dimensional data acquired in the three-dimensional data acquiring step by a predetermined length to generate divided three-dimensional data. The image data converting step connects a plurality of the divided three-dimensional data generated in the divided three-dimensional data generating step to convert the data into the image data (second method).

[0034] This makes it possible to reduce the volume of data output from the acquisition section in the three-dimensional data acquisition step, thereby reducing the load on the device when reading symbols.

[0035] In the first method, the symbol reading step includes a data extraction step of extracting a predetermined range of image data from the image data obtained in the image data conversion step at a predetermined position from the reference symbol in the arrangement direction of the embossed symbol, and a reading execution step of reading the embossed symbol using the image data of the range extracted in the data extraction step (third method).

[0036] This makes it possible to reduce the volume of image data required when reading a embossed symbol, thereby reducing the load on the device when reading the embossed symbol from image data.

[0037] Moreover, since image data of a predetermined range in which a embossed symbol is to be read can be extracted from the image data, it is possible to prevent image data outside the predetermined range from being read by mistake, and therefore it is possible to read the embossed symbol to be read from the image data with higher accuracy.

[0038] In the first method, the three-dimensional data acquisition step acquires three-dimensional data in which the inner wall and the outer wall of the pipe each become the contour of the area in which the embossed symbol is read. In the image data conversion step, the contour in the image data is converted into a straight line portion that can distinguish the area from the outside of the area (fourth method).

[0039] This makes it possible to clearly distinguish between the embossed symbol and the outline in the image data. Therefore, when reading the embossed symbol using the image data, it is possible to prevent the outline from being mistakenly read as part of the embossed symbol. Therefore, the embossed symbol can be read with higher accuracy. Effect of the Invention

[0040] A pipe symbol reading device according to one embodiment of the present invention comprises a three-dimensional data acquisition unit that acquires three-dimensional data of the embossed symbol by measuring the height of the embossed symbol relative to the outer surface of the pipe while rotating the pipe relatively around its axis, an image data conversion unit that converts the acquired three-dimensional data into image data in which the embossed symbol is arranged in a straight line, a reference symbol identification unit that identifies in the image data a reference symbol that serves as a reference for starting to read the embossed symbol, and a symbol reading unit that uses the image data to read the embossed symbol based on the reference symbol.

[0041] A method for reading symbols on a pipe according to one embodiment of the present invention includes a three-dimensional data acquisition step of acquiring three-dimensional data of the embossed symbol by measuring the height of the embossed symbol relative to the outer surface of the pipe while rotating the pipe relatively around its axis, an image data conversion step of converting the three-dimensional data acquired in the three-dimensional data acquisition step into image data in which the embossed symbol is arranged in a straight line, a reference symbol identification step of identifying a reference symbol in the image data converted in the image data conversion step that serves as a reference for starting to read the embossed symbol, and a symbol reading step of using the image data to read the embossed symbol based on the reference symbol identified in the reference symbol identification step.

[0042] As a result, the embossed symbol can be read more accurately by identifying a reference symbol in the image data that serves as a reference for starting to read the embossed symbol, and reading the embossed symbol using the reference symbol as a reference. Moreover, even if the blank area disclosed in Patent Document 1 cannot be identified, acquisition of the three-dimensional data is not continued. Therefore, the embossed symbol can be read in a shorter time without unnecessarily lengthening the reading time of the embossed symbol. Therefore, the embossed symbol formed on the outer surface of the pipe can be read more accurately and the reading time of the embossed symbol can be shortened. [Brief description of the drawings]

[0043] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of a symbol reading device. [Diagram 2] FIG. 2 is a view of a three-dimensional data acquisition unit in the symbol reading device shown in FIG. 1 as viewed in the axial direction. [Diagram 3] FIG. 3 is a diagram showing an example of image data converted from three-dimensional data by the image data conversion unit. [Figure 4] FIG. 4 is a flowchart showing a method for reading symbols on pipes in the first embodiment. [Diagram 5] FIG. 5 is a diagram showing a schematic configuration of a pipe symbol reading device according to the second embodiment. [Figure 6] FIG. 6 is a diagram showing an example of how the acquired divided three-dimensional data is converted into connected image data in the symbol reading device shown in FIG. [Figure 7] FIG. 7 is a diagram showing an example of extracted image data in which a part of the image data is extracted by a data extracting unit in the symbol reading device shown in FIG. [Figure 8] FIG. 8 is a flowchart showing a method for reading symbols on a pipe in the second embodiment. [Figure 9] FIG. 9 is a diagram showing a schematic configuration of a pipe symbol reading device according to the third embodiment. [Figure 10] FIG. 10 is a diagram showing an example of image data converted by an image data conversion unit in the symbol reading device shown in FIG. 9, where (a) shows an example of image data including contour image data, and (b) shows an example of image data including a straight line portion converted from the contour image data. [Figure 11] Figure 11 shows an example of image data in which straight line portions and embossed symbol image portions are emphasized, and an example of image data in which images that are not to be read have been removed by an image data filter unit, where (a) shows an example of image data in which straight line portions and embossed symbol image portions are emphasized, and (b) shows an example of image data in which images that are not to be read have been removed. [Figure 12]FIG. 12 is a flowchart showing a method for reading symbols on a tube in the third embodiment. [Figure 13] FIG. 13 is a diagram showing how, in another embodiment, image data of one or more revolutions is used to read a embossed symbol at a reading target portion located at a predetermined position in the opposite direction to one direction in which the embossed symbols are arranged relative to a reference symbol. [Figure 14] FIG. 14 is a diagram showing an example of extracted image data in which a part of the image data is extracted by a data extracting unit in the symbol reading device shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0044] Each embodiment will be described below with reference to the drawings. In each drawing, the same parts are given the same reference numerals, and the description of the same parts will not be repeated. Note that the dimensions of the components in each drawing do not faithfully represent the actual dimensions of the components and the dimensional ratios of each component.

[0045] In the following description, the axial direction refers to the direction in which the axis P of the pipe 99 extends. The radial direction refers to the direction perpendicular to the axis P of the pipe 99. The circumferential direction refers to the direction in which the outer circumferential surface of the pipe 99 extends when the pipe 99 is viewed in the axial direction.

[0046] In the following description, the terms "fix," "connect," and "attach" (hereinafter referred to as "fixing") include not only cases where members are directly fixed to each other, but also cases where members are fixed to each other via other members. In other words, in the following description, the terms "fixing" include the meanings of direct and indirect fixing of members to each other.

[0047] [Embodiment 1] (Overall composition) Fig. 1 is a diagram showing a schematic configuration of a symbol reading device 1 for a pipe 99 according to an embodiment of the present invention. Fig. 2 is a diagram showing a three-dimensional data acquisition unit 10 of the symbol reading device 1 shown in Fig. 1 as viewed in the axial direction. The symbol reading device 1 is a device for reading a relief symbol 90 formed on an end surface 99a of a pipe 99 to be measured.

[0048] The pipe 99 is, for example, a cast iron pipe used as a water pipe. The pipe 99 has a cylindrical shape extending along an axis P. An axial end face 99a of the pipe 99 is formed with a concave-convex symbol 90 indicating the nominal diameter, manufacturing plant, manufacturing year, lot number, manufacturer, etc. of the pipe 99. The concave-convex symbol 90 is composed of a convex portion, a concave portion, or a combination of a convex portion and a concave portion. The end face 99a is a part of the outer surface of the pipe 99 and is located at the end of the pipe 99 in the axial direction.

[0049] As shown in Fig. 2, the embossed symbols 90 are formed on an end surface 99a of a pipe 99 so as to be aligned in the circumferential direction. The embossed symbols 90 are formed on the end surface 99a of the pipe 99 by, for example, casting, laser cutting, or the like. The embossed symbols 90 include letters 91, figures 92, or a combination of letters 91 and figures 92. The letters 91 are words, numbers, or the like. The figures 92 are pictographic marks, or the like.

[0050] 1, the symbol reading device 1 has a three-dimensional data acquisition unit 10 and a control unit 30. The symbol reading device 1 acquires three-dimensional data of a relief symbol 90 formed on an end surface 99a of a pipe 99 by using the three-dimensional data acquisition unit 10 while rotating the pipe 99 around an axis P.

[0051] The three-dimensional data acquisition unit 10 includes a rotation drive unit 5 , a data acquisition unit main body 11 , and a data storage unit 12 .

[0052] The rotary drive unit 5 includes a plurality of roller units 5a that rotatably support the tube 99 from below. The rotary drive unit 5 rotates the tube 99 about the axis P by rotating the plurality of roller units 5a.

[0053] The data acquisition unit main body 11 uses a known light cutting method to measure two-dimensional data including radial position information on the end face 99a of the pipe 99 and height information at that position. As shown in Fig. 2, the data acquisition unit main body 11 measures the two-dimensional data on the end face 99a of the pipe 99 that is relatively rotated by the rotation drive unit 5. This allows the three-dimensional data acquisition unit 10 to acquire three-dimensional data including radial and circumferential position information on the end face 99a of the pipe 99 and height information at that position. The three-dimensional data includes three-dimensional data of the relief symbol 90 formed on the end face 99a.

[0054] The data storage unit 12 has a configuration capable of storing the three-dimensional data. The data storage unit 12 is, for example, a hard disk, an SSD, a RAM, a USB memory, a CD-ROM, etc. The data storage unit 12 may be a device or equipment of any configuration as long as it has a configuration capable of storing data. The three-dimensional data stored in the data storage unit 12 is output to the image data conversion unit 40 of the control unit 30.

[0055] (Control unit) The control unit 30 controls the reading of the embossed symbol 90 in the symbol reading device 1. The control unit 30 has a measurement control unit 20, a reading control unit 33, and a storage unit 75.

[0056] The measurement control unit 20 controls the acquisition of the three-dimensional data by the three-dimensional data acquisition unit 10, and also controls the rotation of the tube 99 by the rotation drive unit 5. Specifically, the measurement control unit 20 controls the rotation drive unit 5 so that the roller units 5a relatively rotate the tube 99 in a direction opposite to one direction in which the uneven symbols 90 are arranged. In the example shown in FIG. 2, the measurement control unit 20 drives the roller units 5a so that the tube 99 rotates in a counterclockwise direction which is opposite to the clockwise direction in which the uneven symbols 90 are arranged. In addition, the measurement control unit 20 controls the three-dimensional data acquisition unit 10 so as to acquire the three-dimensional data of the uneven symbols 90 formed on the end surface 99a of the tube 99.

[0057] (Read control section) The reading control unit 33 reads the embossed symbol 90 formed on the end surface 99a of the pipe 99, using the three-dimensional data of the embossed symbol 90 acquired by the three-dimensional data acquisition unit 10. The reading control unit 33 has an image data conversion unit 40, a reference symbol identification unit 50, and a symbol reading unit 60.

[0058] 3 is a diagram showing an example of image data 41 converted from the three-dimensional data by the image data conversion unit 40. As shown in FIG. 3, the image data conversion unit 40 converts the three-dimensional data acquired by the three-dimensional data acquisition unit 10 into image data 41 in which the relief symbols 90 are arranged in a straight line. The image data conversion unit 40 converts, for example, the three-dimensional data into image data 41 in which the height information of the relief symbols 90 is expressed by color brightness. The image data 41 includes a relief symbol image section 49 which is an image of the relief symbol 90. The relief symbol image section 49 is image data that displays the characters 91 and figures 92 of the relief symbol 90.

[0059] The image data conversion unit 40 may perform image processing to make the embossed symbol image unit 49 clearer. The image processing may be, for example, a process of adjusting the range of the color brightness with respect to the height information, a binarization process, etc. This allows the reference symbol identification unit 50 described later to easily identify the reference symbol 51 in the embossed symbol image unit 49, and the symbol reading unit 60 described later to easily read the embossed symbol 90 in the embossed symbol image unit 49.

[0060] The reference symbol identification unit 50 identifies the reference symbol 51 in the embossed symbol image unit 49. The reference symbol identification unit 50 identifies the reference symbol 51, for example, by comparing the reference symbol registration data stored in advance in the storage unit 75 with the image data of the embossed symbol 90 in the embossed symbol image unit 49. The reference symbol identification unit 50 identifies the reference symbol 51, for example, by comparing the degree of coincidence of the shapes of the symbols. For example, in FIG. 3, the reference symbol identification unit 50 identifies a "water mark", which is a symbol having a high degree of coincidence of the shape of the reference symbol registration data, as the reference symbol 51. The reference symbol identification unit 50 may identify a embossed symbol other than the "water mark" as the reference symbol 51 in the embossed symbol image unit 49. The reference symbol 51 is a symbol that serves as a reference when the symbol reading unit 60 starts an operation to read the embossed symbol 90.

[0061] 3, the symbol reading unit 60 reads the embossed symbol 90 in a reading target portion 61 of the embossed symbol image portion 49 using the reference symbol 51 as a reference. The reading target portion 61 is a portion of the embossed symbol image portion 49 that contains image data of the embossed symbol 90 to be read.

[0062] Symbol reading unit 60 may read only characters in reading target unit 61. Symbol reading unit 60 may have, for example, the function of a known optical character recognition (OCR) system. Symbol reading unit 60 may output the result of the reading to storage unit 75 as symbol data.

[0063] For example, the symbol reading unit 60 reads the embossed symbol 90 in the reading target portion 61 located behind the reference symbol 51 in one direction, which is the arrangement direction of the embossed symbol 90, in the embossed symbol image portion 49 of the image data 41. In the example shown in Fig. 3, the symbol reading unit 60 reads the embossed symbol 90 in the reading target portion 61 located behind the "water mark" identified as the reference symbol 51. In the example shown in Fig. 3, the symbol reading unit 60 reads the characters "DS22F150GX112" in the reading target portion 61.

[0064] The storage unit 75 may store the reference symbol registration data, as well as the symbol data output from the symbol reading unit 60. The storage unit 75 is, for example, a storage medium such as a hard disk, an SSD, a RAM, a USB memory, or a CD-ROM. The storage unit 75 may be a device or equipment of any configuration as long as it has a configuration capable of storing data. The storage unit 75 may be provided separately from the control unit 30.

[0065] According to the above-mentioned configuration, the three-dimensional data acquisition unit 10 can acquire the three-dimensional data of the embossed symbols 90 arranged in the circumferential direction on the end face 99a, which is the outer peripheral surface of the pipe 99. Then, the image data conversion unit 40 can convert the three-dimensional data into image data 41 in which the embossed symbols 90 (embossed symbol image portion 49) are arranged in a straight line. Then, the reference symbol identification unit 50 can identify the reference symbol 51 in the image data 41, which serves as a reference for starting to read the embossed symbol 90. The symbol reading unit 60 can read the embossed symbol 90 using the reference symbol 51 as a reference, by using the image data 41. In this way, the symbol reading device 1 can read the embossed symbol 90 formed on the end face 99a of the pipe 99.

[0066] This allows the symbol reading device 1 to more accurately read the embossed symbol 90 on the pipe 99 from the image data 41. Moreover, even if the blank area disclosed in Patent Document 1 cannot be identified, the reference symbol 51 is identified in the image data 41 converted from the three-dimensional data, so that acquisition of the three-dimensional data is not continued. Therefore, the reading time for the embossed symbol is not unnecessarily extended, and the embossed symbol 90 can be read in a shorter time.

[0067] Therefore, the symbol reading device 1 having the above-mentioned configuration can read the embossed symbol 90 formed on the outer surface of the pipe 99 with higher accuracy and can also shorten the time required to read the embossed symbol.

[0068] Moreover, the symbol reading device 1 does not require a blank area as disclosed in Patent Document 1. Therefore, the symbol reading device 1 having the above-mentioned configuration can also read the embossed symbol 90 formed on the outer peripheral surface of the pipe 99 where the blank area cannot be identified. Therefore, a symbol reading device 1 with higher versatility can be realized.

[0069] Furthermore, as described above, the three-dimensional data acquisition unit 10 acquires the three-dimensional data of the uneven symbols 90 while relatively rotating the pipe 99 in the direction opposite to the one direction in which the uneven symbols 90 are arranged, so that the three-dimensional data of the uneven symbols 90 can be acquired in the one direction in which the uneven symbols 90 are arranged. Therefore, the uneven symbols 90 can be read more quickly and more reliably.

[0070] In addition, as described above, the symbol reading unit 60 uses the image data 41 to read the embossed symbol 90 in the reading target portion 61 located behind the reference symbol 51 in one direction, which is the arrangement direction of the embossed symbol 90. This makes it possible to read the embossed symbol 90 more reliably.

[0071] (How to read pipe symbols) Next, a method for reading the embossed symbol 90 formed on the end surface 99a of the pipe 99 using the symbol reading device 1 having the above-mentioned configuration (symbol reading method) will be described with reference to Fig. 4. Fig. 4 is a flowchart showing the symbol reading method in the first embodiment.

[0072] 4 starts (START), first in step SA1, the data acquisition unit main body 11 acquires three-dimensional data by measuring height information of the embossed symbol 90 on the end face 99a while the rotation drive unit 5 of the three-dimensional data acquisition unit 10 is rotating the pipe 99. In the following step SA2, the image data conversion unit 40 converts the three-dimensional data into image data 41. The image data 41 includes a embossed symbol image portion 49.

[0073] Thereafter, in step SA 3 , the reference symbol identification unit 50 identifies the reference symbol 51 from within the embossed symbol image portion 49 .

[0074] In the next step SA4, the symbol reading unit 60 uses the reference symbol 51 as a reference for starting operation and reads the embossed symbol 90 in the reading target portion 61 of the embossed symbol image portion 49. After that, this flow ends (END).

[0075] Here, step SA1 corresponds to a three-dimensional data acquisition step, step SA2 corresponds to an image data conversion step, step SA3 corresponds to a reference symbol identification step, and step SA4 corresponds to a symbol reading step.

[0076] According to the above-mentioned method, three-dimensional data of the embossed symbols 90 arranged in the circumferential direction on the outer peripheral surface of the pipe 99 is acquired in step SA1, and image data 41 in which the embossed symbols 90 (embossed symbol image portion 49) are arranged in a straight line can be obtained from the three-dimensional data. Then, the reference symbol 51 can be identified in the embossed symbol image portion 49. Therefore, the embossed symbol 90 can be read in the reading target portion 61 of the embossed symbol image portion 49 using the reference symbol 51 as a reference.

[0077] This allows the symbol reading device 1 to more accurately read the embossed symbol 90 on the pipe 99 using the image data 41. Moreover, even if the symbol reading device 1 cannot identify a blank area as disclosed in Patent Document 1, it can identify the reference symbol 51 in the image data 41 converted from the three-dimensional data. Therefore, the acquisition of the three-dimensional data by the three-dimensional data acquisition unit 10 is not continued. Therefore, the reading time for the embossed symbol is not unnecessarily extended, and the embossed symbol 90 can be read in a shorter time.

[0078] Therefore, the above-described symbol reading method can read the embossed symbol 90 formed on the outer surface of the pipe 99 with higher accuracy and can also shorten the time required to read the embossed symbol.

[0079] [Embodiment 2] Fig. 5 shows a schematic configuration of symbol reading device 200 according to embodiment 2. The configuration of control unit 230 of symbol reading device 200 according to this embodiment differs from the configuration of control unit 30 of symbol reading device 1 according to embodiment 1. In the following, the same components as those in embodiment 1 are given the same reference numerals and their description will be omitted, and only the components different from embodiment 1 will be described. Fig. 6 is a diagram showing a schematic example of how acquired divided three-dimensional data 215 is converted into linked image data 241 in symbol reading device 200.

[0080] As shown in FIG. 5, a symbol reading device 200 according to the second embodiment includes a three-dimensional data acquisition unit 210 and a control unit 230.

[0081] As shown in FIGS. 5 and 6, the three-dimensional data acquisition unit 210 divides the acquired three-dimensional data into data of a predetermined data length, and outputs the divided data to the image data conversion unit 240 as divided three-dimensional data 215.

[0082] The three-dimensional data acquisition unit 210 may, for example, divide the acquired three-dimensional data in real time and output the divided data to the image data conversion unit 240 as divided three-dimensional data 215. In addition, the three-dimensional data acquisition unit 210 may, for example, divide the three-dimensional data stored in the data storage unit 12 into data of a predetermined data length and output the divided data to the image data conversion unit 240 as divided three-dimensional data 215.

[0083] The control unit 230 has a measurement control unit 20, a reading control unit 233, and a storage unit 75. The reading control unit 233 has an image data conversion unit 240, a reference symbol identification unit 50, and a symbol reading unit 260.

[0084] The image data conversion unit 240 converts the multiple divided three-dimensional data 215 into concatenated image data 241 by concatenating the multiple divided three-dimensional data 215 in one direction, which is the arrangement direction of the concave-convex symbols 90. Except for concatenating the multiple divided three-dimensional data 215, the method of converting the multiple divided three-dimensional data 215 into concatenated image data 241 is the same as the method of converting three-dimensional data into image data 41 in embodiment 1. The concatenated image data 241 corresponds to the image data of the present invention.

[0085] The symbol reading unit 260 extracts a portion of the image data 41, and uses the extracted image data to read the embossed symbol 90. In more detail, the symbol reading unit 260 includes a data extraction unit 261 and a reading execution unit 262.

[0086] 7 and 14 are diagrams showing an example of extracted image data 242 obtained by extracting a part of image data 41 by data extraction unit 261 in symbol reading device 200. As shown in Fig. 7 and Fig. 14, data extraction unit 261 extracts, as extracted image data 242, a predetermined range of image data from linked image data 241 at a predetermined position from reference symbol 51 in the arrangement direction of embossed symbol 90.

[0087] The predetermined position is a position including the portion to be read 61, and is a position that is set in advance based on, for example, the reference symbol 51. The predetermined range is a range including the portion to be read 61, and is a range whose size is set in advance, for example. Within the predetermined range, thresholds are set for area, line length (including the length of the character in the vertical and horizontal directions), line thickness, roundness, and the like, and the symbol reading unit 260 may not read the image as a concave-convex symbol 90 if any one of them is below the threshold. When multiple image data of the predetermined range are extracted, the same threshold may be set for each of the extracted image data, or different thresholds may be set.

[0088] 7, the data extraction unit 261 extracts, from the concave-convex symbol 90 in the concave-convex symbol 90 arrangement direction in the combined image data 241 obtained by rotating the tube 99 multiple times, a range of a specified data length from the reference symbol 51 in the concave-convex symbol 90 arrangement direction, that is, a specified data length range (predetermined range) including the reading target portion 61 with the reference symbol 51 being the "water mark" as the reference symbol, as extracted image data 242. Therefore, in the example shown in FIG. 7, the predetermined position is the position immediately behind the reference symbol 51 being the "water mark" in the concave-convex symbol 90 arrangement direction.

[0089] 14, the data extraction unit 261 extracts image data of a predetermined range at a plurality of predetermined positions relative to the "water mark" which is the reference symbol 51 in the arrangement direction of the embossed symbol 90 in the combined image data 241, as a plurality of extracted image data 243. In the example shown in FIG. 14, the predetermined positions are a plurality of positions in the combined image data 241, and the predetermined ranges are different depending on the positions. It is preferable that the predetermined range is a range narrower than the thickness D of the end face 99a of the pipe 99 in the thickness direction of the end face 99a of the pipe 99 in the combined image data 241 (the width direction of the image in FIG. 14).

[0090] The method of extracting image data from the linked image data 241 by the data extracting unit 261 is not limited to the examples shown in Fig. 7 and Fig. 14. In other words, the method of extracting image data from the linked image data 241 may be any method as long as the read target portion 61 is included in the image data.

[0091] The reading execution unit 262 reads the embossed symbol 90 from the reading target portion 61 included in the extracted image data 242 or 243 .

[0092] According to the above-mentioned configuration, by dividing the three-dimensional data into a plurality of pieces and outputting the divided pieces of data to the image data conversion unit 240 as divided three-dimensional data 215, it is possible to reduce the amount of data output from the three-dimensional data acquisition unit 210 to the image data conversion unit 240. Therefore, it is possible to reduce the load of data processing and data transmission on the symbol reading device 200.

[0093] Moreover, by dividing the three-dimensional data into a predetermined data length, the reading control unit 233 can obtain the linked image data 241 including the reading target portion 61 in a shorter time. Therefore, the symbol reading device 200 can read the embossed symbol 90 in a shorter time.

[0094] Furthermore, by the data extraction unit 261 extracting the extracted image data 242 and 243 from the linked image data 241, it is possible to reduce the data capacity of the image when reading the embossed symbol 90. Therefore, it is possible to further reduce the load on the symbol reading device 200 when reading the embossed symbol 90 from the linked image data 241.

[0095] Moreover, since image data within a predetermined range in which the embossed symbol 90 is to be read can be extracted as the extracted image data 242 or 243 from the linked image data 241, it is possible to prevent image data outside the predetermined range from being read by mistake. Therefore, the embossed symbol 90 to be read can be read more accurately from the extracted image data 242 or 243.

[0096] (How to read pipe symbols) Next, a method for reading the embossed symbol 90 formed on the end surface 99a of the pipe 99 using the symbol reading device 200 having the above-mentioned configuration (symbol reading method) will be described with reference to Fig. 8. Fig. 8 is a flowchart showing the symbol reading method in the second embodiment.

[0097] 8 starts (START), first, in step SB1, three-dimensional data is acquired by the three-dimensional data acquisition unit 210, similar to step SA1 in embodiment 1. In the following step SB2, the three-dimensional data is divided into data of a predetermined data length to generate divided three-dimensional data 215.

[0098] Thereafter, in step SB3, the multiple divided three-dimensional data 215 are linked in one direction, which is the arrangement direction of the concave-convex symbols 90, and converted into linked image data 241.

[0099] In step SB4, similarly to step SA3 in the first embodiment, the reference symbol 51 is identified in the embossed symbol image portion 49.

[0100] In the next step SB5, the data extraction unit 261 extracts image data of a predetermined range from the reference symbol 51 at a predetermined position in the arrangement direction of the embossed symbol 90 in the linked image data 241. As a result, extracted image data 242 or 243 is obtained.

[0101] In step SB6, the reading execution unit 262 uses the extracted image data 242 or 243 to read the embossed symbol 90 from the reading target portion 61. After that, this flow ends (END).

[0102] Here, step SB1 corresponds to the three-dimensional data acquisition step, step SB2 corresponds to the divided three-dimensional data generation step, step SB3 corresponds to the image data conversion step, step SB4 corresponds to the reference symbol identification step, step SB5 corresponds to the data extraction step, step SB6 corresponds to the reading execution step, and steps SB5 and SB6 correspond to the symbol reading step.

[0103] According to the above-mentioned method, the amount of data output from the three-dimensional data acquisition unit 210 to the image data conversion unit 240 can be reduced by dividing the three-dimensional data into a plurality of pieces and outputting the divided pieces of data to the image data conversion unit 240 as divided three-dimensional data 215. This reduces the load of data processing and data transmission on the symbol reading device 200.

[0104] In addition, a portion of the linked image data 241 is extracted as the extracted image data 242 or 243, and the embossed symbol 90 is read in the extracted image data 242 or 243, so that the capacity of the image data used to read the embossed symbol 90 can be reduced. Therefore, the load on the symbol reading device 200 when reading the embossed symbol 90 from the linked image data 241 can be reduced.

[0105] Moreover, since image data within a predetermined range in which the embossed symbol 90 is to be read can be extracted as the extracted image data 242 or 243 from the linked image data 241, it is possible to prevent image data outside the predetermined range from being read by mistake. Therefore, the embossed symbol 90 to be read can be read more accurately from the extracted image data 242 or 243.

[0106] [Embodiment 3] 9 shows a schematic configuration of a symbol reading device 300 according to embodiment 3. The configuration of a control unit 330 of symbol reading device 300 according to this embodiment differs from the configuration of control unit 30 of embodiment 1. In the following, the same components as those in embodiment 1 are denoted by the same reference numerals and description thereof will be omitted, and only the components different from embodiment 1 will be described.

[0107] As shown in FIG. 9, a symbol reading device 300 according to the third embodiment includes a three-dimensional data acquisition unit 10 and a control unit 330.

[0108] The three-dimensional data acquisition unit 10 acquires three-dimensional data in which the inner wall 397 and the outer wall 398 of the pipe 99 each define the outline of the area in which the uneven symbol 90 is read.

[0109] The control unit 330 has a measurement control unit 20, a reading control unit 333, and a storage unit 75. The reading control unit 333 has an image data conversion unit 340, a reference symbol identification unit 50, an image data filter unit 385, and a symbol reading unit 60.

[0110] Fig. 10 is a diagram showing an example of image data 341A, 341B converted by the image data conversion unit 340. As shown in Fig. 10(a), the image data conversion unit 340 converts the three-dimensional data including the contour into image data 341A. The image data 341A includes a contour image portion 345 in which the contour is converted into an image.

[0111] 10(b), the image data conversion unit 340 converts the image data 341A into image data 341B in which the contour image portion 345 is converted into a straight line portion L. The straight line portion L is, for example, a straight line image in which the contour image portion 345 is thickened and emphasized. The straight line portion L makes it possible to more clearly distinguish the area including the concave-convex symbol image portion 49 from the outside of that area.

[0112] 11 is a diagram showing an example of image data 341C in which the straight line portion L and the embossed symbol image portion 49 are emphasized, and image data 341D in which the image 347 not to be read is removed by the image data filter unit 385. As shown in FIG. 11(a), the image data filter unit 385 performs binarization processing or the like on the image data 341B to generate image data 341C in which the straight line portion L and the embossed symbol image portion 49 are emphasized.

[0113] 11(b), the image data filter unit 385 generates image data 341D by removing an image 347 that is not to be read from image data 341C. The image 347 that is not to be read includes not only symbols but also contour image portion 345, straight line portion L, etc. For example, in FIG. 11, the image data filter unit 385 removes an image 347 of a predetermined figure in straight line portion L and concave-convex symbol image portion 49, which are not to be read, from image data 341C.

[0114] The image data filter unit 385 can set thresholds for parameters such as image shape, length, area, circularity, and brightness difference, and select images 347 below the thresholds as images not to be read.

[0115] According to the above-mentioned configuration, the difference between the embossed symbol image portion 49 and the contour image portion 345 in the image data 341A can be made clear. Furthermore, the difference between the embossed symbol image portion 49 and the straight line portion L in the image data 341B can be made clearer by the straight line portion L in which the contour image portion 345 is emphasized. Therefore, the difference between the embossed symbol image portion 49 and the straight line portion L can also be made clearer in the image data 341C obtained by performing a binarization process or the like on the image data 341B. Therefore, the image data filter unit 385 can more reliably remove the image 347 that is not to be read from the image data 341C.

[0116] By generating image data 341D by image data filter unit 385 as described above, symbol reading unit 60 can read embossed symbol 90 in reading target area 61 from which image 347 not to be read has been removed. Therefore, only embossed symbol 90 to be read can be read with high accuracy in image data 341D.

[0117] (How to read pipe symbols) Next, a method for reading the embossed symbol 90 formed on the end surface 99a of the pipe 99 using the symbol reading device 300 having the above-mentioned configuration (symbol reading method) will be described with reference to Fig. 12. Fig. 12 is a flowchart showing the symbol reading method in the third embodiment.

[0118] When the flow shown in FIG. 12 starts (START), first, in step SC1, The original data acquisition unit 10 acquires three-dimensional data in which the inner wall 397 and the outer wall 398 of the pipe 99 each become the contour of the area in which the embossed symbol 90 is read. In the following step SC2, the three-dimensional data is converted into image data 341A having a contour image portion 345. Then, the image data 341A is converted into image data 341B having a straight line portion L.

[0119] Thereafter, in step SC3, the reference symbol identification unit 50 identifies the reference symbol 51 in the embossed symbol image area 49, similarly to step SA3 in the first embodiment.

[0120] In the next step SC4, the image data filter unit 385 generates image data 341C in which the straight line portion L and the embossed symbol image portion 49 are emphasized. After that, the image data filter unit 385 removes the image 347 that is not to be read from the image data 341C to generate image data 341D.

[0121] In step SC5, the image data 341D is used to read the embossed symbol 90 in the reading target section 61. After that, this flow ends (END).

[0122] Here, step SC1 corresponds to a three-dimensional data acquisition step, step SC2 corresponds to an image data conversion step, step SC3 corresponds to a reference symbol identification step, step SC4 corresponds to an image filtering step, and step SC5 corresponds to a symbol reading step.

[0123] According to the above-mentioned method, the difference between the embossed symbol image portion 49 and the contour image portion 345 in the image data 341A can be made clear. Furthermore, the difference between the embossed symbol image portion 49 and the straight line portion L in the image data 341B can be made clearer by the straight line portion L in which the contour image portion 345 is emphasized. Therefore, the difference between the embossed symbol image portion 49 and the straight line portion L can also be made clearer in the image data 341C obtained by performing a binarization process or the like on the image data 341B. Therefore, the image 347 that is not to be read can be more reliably removed from the image data 341C.

[0124] By generating the image data 341D as described above, the symbol reading unit 60 can read the embossed symbol 90 in the reading target area 61 from which the image 347 that is not to be read has been removed. Therefore, only the embossed symbol 90 to be read in the image data 341D can be read with high accuracy. Therefore, the embossed symbol 90 formed on the outer surface of the pipe 99 can be read with high accuracy.

[0125] (Other embodiments) Although the embodiment of the present invention has been described above, the above-mentioned embodiment is merely an example for carrying out the present invention. Therefore, the present invention is not limited to the above-mentioned embodiment, and it is possible to carry out the above-mentioned embodiment by appropriately modifying it within the scope of the gist of the present invention.

[0126] In each of the above embodiments, the symbol reading unit 60, 260 reads the embossed symbol 90 in the reading target portion 61 located in one direction, which is the arrangement direction of the embossed symbol 90 relative to the reference symbol 51, in the image data 41 or the linked image data 241.

[0127] FIG. 13 is a diagram showing how image data of one or more revolutions is used to read a embossed symbol 90 in a reading target portion located at a predetermined position in a direction opposite to one direction in which the embossed symbols are arranged relative to the reference symbol.

[0128] As shown in Figure 13, the symbol reading unit may read a embossed symbol 90 at a reading target portion located at a predetermined position in the opposite direction to one direction in which the embossed symbols are arranged relative to the reference symbol, using image data of one or more revolutions converted by an image data conversion unit from three-dimensional data of one or more revolutions acquired by a three-dimensional data acquisition unit.

[0129] As a result, even if the reference symbol in a previous rotation is erroneously determined to be another symbol and the reference symbol cannot be identified in the image data obtained from the three-dimensional data acquired while the tube is rotated one or more times, the embossed symbol 90 can be read in the reading target portion located at a specified position in the opposite direction to the one direction in which the embossed symbols are arranged, relative to the reference symbol identified by the reference symbol identification unit in a subsequent rotation. Therefore, the embossed symbol can be read more reliably.

[0130] The symbol reading device 1 of the first embodiment may have at least a part of the configuration of the symbol reading device 200 of the second embodiment and the configuration of the symbol reading device 300 of the third embodiment. Moreover, the symbol reading device 200 of the second embodiment may have at least a part of the configuration of the symbol reading device 1 of the first embodiment and the configuration of the symbol reading device 300 of the third embodiment. Moreover, the symbol reading device 300 of the third embodiment may have at least a part of the configuration of the symbol reading device 1 of the first embodiment and the configuration of the symbol reading device 200 of the second embodiment.

[0131] In each of the above-described embodiments, the reference symbol identification unit 50 identifies one reference symbol 51 from the embossed symbol image portion 49. However, the reference symbol identification unit may identify multiple reference symbols. This allows the symbol reading unit to read the embossed symbol in the reading target portion using the other reference symbols as references even if one reference symbol is unclear.

[0132] In each of the above-described embodiments, the symbol reading unit 60, 260 reads the embossed symbol 90 in the reading target area 61 using the reference symbol 51 as a reference. However, the symbol reading unit may read the embossed symbol in the embossed symbol image area using the reference symbol as a reference without specifying the reading target area.

[0133] In each of the above-described embodiments, the reading target portion 61 is located in one direction, which is the arrangement direction of the embossed symbols 90, with the reference symbol 51 as a reference. However, the reading target portion may be located a predetermined distance away from the reference symbol in the one direction. The position, size, range, etc. of the reading target portion may be determined depending on the type of pipe to be measured.

[0134] In each of the above-described embodiments, the reading control unit 33, 233, 333 does not have a function of outputting. However, the reading control unit may further have an output unit that outputs the symbol read by the symbol reading unit to the outside of the symbol reading device. This makes it easier to read the embossed symbol. The output unit may output to a display unit included in the symbol reading device without outputting to the outside of the symbol reading device. The display unit may display the symbol read by the symbol reading unit.

[0135] In each of the above embodiments, the pipe 99 is a cast iron pipe used as a water pipe. However, the pipe may be a pipe other than a cast iron pipe. The pipe may be a pipe made of other metals, such as steel, stainless steel, etc. The pipe may also be a pipe made of other resins, such as polyvinyl chloride. The pipe may be a pipe made of mortar, concrete, etc. The pipe may be a pipe other than a water pipe.

[0136] In the second embodiment, the three-dimensional data acquisition unit 10 divides the three-dimensional data to generate divided three-dimensional data 215. Then, the image data conversion unit 240 converts the divided three-dimensional data 215 into connected image data 241. However, the three-dimensional data acquisition unit does not have to generate divided three-dimensional data from the three-dimensional data. In this case, the image data conversion unit converts the three-dimensional data that is not divided three-dimensional data into image data.

[0137] In the second embodiment, the control unit 230 has a data extraction unit 261. The data extraction unit 261 extracts the extracted image data 242 or 243 from the linked image data 241. However, the data extraction unit may extract the extracted image data from image data that is not linked image data. The control unit may not extract the extracted image data from the image data. In other words, the control unit may not include a data extraction unit.

[0138] In the third embodiment, the image data conversion unit 340 converts the contour image portion 345 into the straight line portion L. However, the image data conversion unit does not have to convert the contour image portion into a straight line portion.

[0139] In the third embodiment, the image data filter unit 385 generates image data 341C by performing binarization processing or the like on image data 341B including straight line portion L. However, the image data filter unit may generate image data in which the contour image portion is emphasized by performing binarization processing or the like on image data including a contour image portion.

[0140] In the third embodiment, the image data filter unit 385 emphasizes the straight line portion L and the embossed symbol image portion 49, etc., and removes the image 347 that is not to be read from the image data 341C. However, the image data filter unit does not have to perform the emphasizing image processing. In this case, the image data filter unit may remove the image that is not to be read from the image data before the emphasizing image processing is performed. The image data filter unit does not have to remove the image that is not to be read from the image data.

[0141] In the third embodiment, the symbol reading unit 60 reads the embossed symbol 90 using image data 341D from which the image 347 not to be read has been removed. However, the symbol reading unit may read the embossed symbol from image data from which the image not to be read has not been removed. In other words, the symbol reading unit may read the embossed symbol from image data including a contour image portion and a straight line portion from which the image not to be read has not been removed, or from image data that has been subjected to image processing for emphasis.

[0142] In each of the above-described embodiments, the three-dimensional data acquisition unit 10, 210 acquires three-dimensional data of the relief symbol 90 formed on the end face 99a of the pipe 99 by the data acquisition unit main body 11 while rotating the pipe 99 around the axis P by the rotation drive unit 5. However, the three-dimensional data acquisition unit may acquire three-dimensional data by rotating the data acquisition unit main body relative to the fixed end face of the pipe. In this case, the three-dimensional data acquisition unit has a movement mechanism that moves the data acquisition unit main body relative to the pipe. [Industrial Applicability]

[0143] INDUSTRIAL APPLICABILITY The present invention can be used in a symbol reading device that reads a rugged symbol formed on the outer surface of a pipe by recesses or protrusions aligned in one circumferential direction. [Explanation of symbols]

[0144] 1, 200, 300 symbol reader 5 Rotation drive unit 5a Roller part 10, 210 3D data acquisition section 11 Data acquisition unit body 12 Data storage unit 20 Measurement control section 30, 230, 330 Control section 33, 233, 333 Reading control section 40, 240, 340 Image data conversion section 41, 341A, 341B, 341C, 341D Image data 49 Raised symbol image section 50 Reference symbol identification section 51 Reference symbol 60, 260 Symbol reading unit 61 Reading target part 75 Memory section 90 Concave and Convex Symbols 91 characters 92 Shapes 99 tube 99a End face 215 divided 3D data 241 Linked Image Data 242, 243 Extracted image data 261 Data Extraction Unit 262 Read execution unit 345 Contour Image Section 347 Unreadable image 385 Image Data Filter Section 397 Interior wall 398 Exterior Wall L Straight section D Tube end thickness

Claims

1. A symbol reading device for reading a rugged symbol formed on an outer surface of a pipe by recesses or protrusions arranged in one circumferential direction, a three-dimensional data acquisition unit that acquires three-dimensional data of the unevenness symbol by measuring a height of the unevenness symbol with respect to an outer surface of the pipe while rotating the pipe relatively around an axis; an image data conversion unit that converts the acquired three-dimensional data into image data in which the concave-convex symbols are arranged in a straight line; a reference symbol identification unit that identifies a reference symbol in the image data as a reference for starting reading of the embossed symbol; a symbol reading unit that reads the embossed symbol using the image data and the reference symbol as a reference; having Pipe symbol reader.

2. 2. The pipe symbol reading device according to claim 1, The three-dimensional data acquisition unit acquires three-dimensional data of the uneven symbols while relatively rotating the tube in a direction opposite to the one direction which is an arrangement direction of the uneven symbols. Pipe symbol reader.

3. 2. The pipe symbol reading device according to claim 1, the symbol reading unit reads a rugged symbol located behind the reference symbol in the one direction, which is an arrangement direction of the rugged symbols, by using the image data; Pipe symbol reader.

4. 2. The pipe symbol reading device according to claim 1, the three-dimensional data acquisition unit acquires three-dimensional data of the unevenness symbol while relatively rotating the pipe about an axis line by one or more revolutions; the symbol reading unit uses the image data to read a rugged symbol located at a predetermined position in a direction opposite to the one direction, which is an arrangement direction of the rugged symbols, with respect to the reference symbol; Pipe symbol reader.

5. 2. The pipe symbol reading device according to claim 1, the three-dimensional data acquisition unit divides the three-dimensional data into a predetermined data length and outputs the divided three-dimensional data; The image data conversion unit connects a plurality of the divided three-dimensional data to convert the data into the image data. Pipe symbol reader.

6. 2. The pipe symbol reading device according to claim 1, The symbol reading unit is a data extraction unit that extracts image data of a predetermined range from the reference symbol in a direction in which the embossed symbols are aligned, from the image data; a reading execution unit that reads the embossed symbol using image data of the range extracted by the data extraction unit; having Pipe symbol reader.

7. 2. The pipe symbol reading device according to claim 1, The image data filtering unit further includes an image data filtering unit that removes specific symbol data from the image data to generate image data for reading the embossed symbol by the symbol reading unit. Pipe symbol reader.

8. 2. The pipe symbol reading device according to claim 1, The three-dimensional data acquisition unit includes: As the three-dimensional data, three-dimensional data is acquired in which the inner wall and the outer wall of the pipe each become the outline of an area in which the uneven symbol is read; The image data conversion unit converting the contour in the image data into a straight line portion that enables a distinction between the region and the outside of the region; Pipe symbol reader.

9. A method for reading a symbol that reads a rugged symbol formed on an outer surface of a pipe by recesses or protrusions arranged in one circumferential direction, comprising: a three-dimensional data acquisition step of acquiring three-dimensional data of the unevenness symbol by measuring a height of the unevenness symbol with respect to an outer surface of the pipe while rotating the pipe relatively around an axis; an image data conversion step of converting the three-dimensional data acquired in the three-dimensional data acquisition step into image data in which the concave-convex symbols are arranged in a straight line; a reference symbol specifying step of specifying a reference symbol serving as a reference for starting reading of the embossed symbol in the image data converted in the image data converting step; a symbol reading step of reading the embossed symbol using the image data and the reference symbol identified in the reference symbol identifying step as a reference; having How to read pipe symbols.

10. The method for reading symbols on a pipe according to claim 9, The method further includes a divided three-dimensional data generating step of dividing the three-dimensional data acquired in the three-dimensional data acquiring step into a predetermined length to generate divided three-dimensional data, The image data conversion step connects a plurality of the divided three-dimensional data generated in the divided three-dimensional data generation step to convert the data into the image data. How to read pipe symbols.

11. The method for reading symbols on a pipe according to claim 9, The symbol reading step includes: a data extraction step of extracting image data of a predetermined range from the reference symbol in a direction of arrangement of the embossed symbols, from the image data obtained in the image data conversion step; a reading execution step of reading the embossed symbol using image data of the range extracted in the data extraction step; having How to read pipe symbols.

12. The method for reading symbols on a pipe according to claim 9, In the three-dimensional data acquisition step, As the three-dimensional data, three-dimensional data is acquired in which the inner wall and the outer wall of the pipe each become the outline of an area in which the uneven symbol is read; In the image data conversion step, converting the contour in the image data into a straight line portion that enables a distinction between the region and the outside of the region; How to read pipe symbols.

Images